Precipitated calcium carbonate pigment especially for use as ink-jet printing paper coating

FIELD: chemistry.

SUBSTANCE: invention can be used to produce a pigment suitable in making paper for ink-jet printing. Precipitated calcium carbonate is obtained by mixing quicklime with water in a reactor or a tank with a mixer, followed by filtration of the calcium hydroxide suspension to remove all residual contaminants and/or non-reactive quicklime. The filtered suspension is then fed into a stainless steel reactor fitted with a mixer. Temperature is kept in the range of 10-70°C, after which the suspension is fed into a carbonisation reactor, where a carbon dioxide-containing gas is bubbled through the suspension. The carbonisation step is carried out at carbonisation gas flow rate of less than 30 litres per minute per kilogram of calcium hydroxide during precipitation under normal conditions. The suspension is removed from the tank when conductivity reaches the minimum level and pH drops below 8, wherein large particles are removed through a filter. The obtained calcium carbonate can be used as a pigment.

EFFECT: invention improves the quality of ink-jet printing while reducing the cost of production of paper for ink-jet printing.

15 cl, 5 dwg, 17 tbl, 9 ex

 

The technical field to which the invention relates.

The present invention relates to new mineral

the pigments from the besieged varieties of calcium carbonate (PCC).

More specifically, this invention relates to new and improved pigment of precipitated calcium carbonate, which can be used in compositions for coating paper with the aim of obtaining universal coated paper, especially designed for crackastroloka printing, the print quality is the same or similar print properties of commercially available paper high resolution, which requires less manufacturing costs. Universal paper usually used as paper for various types of printing, including black and white copies, laser printing and paper quality for faxes.

The invention additionally relates to the production of these new mineral pigments type of RCC, which are present as solids, in the form of a suspension, suitable for coating on paper designed for crackastroloka printing, using inexpensive device for coating on paper, such as controlling the size press (MSP).

Technical issues

There is a need for universal coated paper, in castnet is, in the paper, suitable for crackastroloka printing, providing superior print quality without a corresponding increase in production costs.

Currently used universal office paper is often associated with poor crackastroloka printing.

One of the major challenges in improving the quality of the print is the increase of optical density of ink applied to the surface of the paper, in particular, after applying a printing ink comprising the dye of the full color spectrum.

Crassostreae printing machine form the image, causing a series of dots of ink on the paper surface. Containing dyes printing inks used for crackastroloka printing, are usually anionic composition with low solids content and, of course, very mobile. Good print quality can be obtained only if the dye ink remains on the paper surface when the solvent of printing ink penetrates into the paper, leaving a uniform round the point to the right place.

It is known that the difference in charges between the adsorbent and adsorbate, respectively, the surface of the paper and dye molecules, usually used to improve the adsorption of the dye.

Therefore, one of the n way of increasing the optical density is to increase the number of cationic centers near the surface of the paper. If the surface of the paper coated with the number of cations present near the surface can be increased by adding cationic additives to the composition for coatings. However, the addition of cationic additives to obtain a given optical density significantly increases the final cost of paper.

The increase of the proportion of cationic additives that stays in a thin layer near the surface of the paper, characterized by retention of the coating, is a second way of increasing optical density. A higher degree of retention of the coating can be achieved by a more narrow distribution of the coating particles by size, which is technically complex and expensive solution.

When using the RCA in the composition for coatings inherent RCC adsorption properties with respect to contained in the printing ink dyes capable of providing another alternative for reducing the number of cationic additives necessary to obtain a given optical density. When the same content of this pigment reducing primary particle size of the PCC increases positively charged surface area of the pigment that can interact with contained in the printing ink dye and link it here. This contributes to the adsorption contained in printing ink dye on the hour izah RCC near the site of application of printing ink, which leads to the increase of optical density.

Segregation of large dye molecules on the surface of the paper also contributes to the exclusion of the size of the surface and cover with a large pore volume, providing the penetration of the solvent into the base paper, while the dye molecules on the surface. This creates a need for a composition for porous pavement; therefore, one of theoretical solutions includes the introduction of the aggregates/agglomerates, such as possibly aggregated pigments in the composition for coating, with carefully controlled distribution of pore size and capillarity. However, as known to a person skilled in the technical field, the specific implementation of such a theoretical solution is quite difficult; according to the specific region U.S. patent US 5750086 (described below), as well as numerous other patents may be obtained finely ground RCC, but not porous products of aggregates/agglomerates.

The second difficulty in improving print quality is the reduction of the migration phenomenon observed after application of printing ink on the paper surface. Migration is contained in the printing ink dye one color to another, neighboring color, is the result of a hidden clutch contained in the printing ink dye with p is the surface of the paper and drying it, and also, in part, because of the slow absorption of solvent ink based paper that provides a contact contained in the printing ink dye to the surface for quick linking. The consequence of this migration is the distortion and reduced sharpness of printed images.

Similarly, bleed also results in blurry images and occurs when the applied printing ink to the contours of the paper. As with migration printing inks, prevent bleed through quick-drying printing ink, while it is preferable for the absorption of the dye, and not adsorption using a porous medium.

As follows from the above, it is necessary to balance and control the adsorption of printing ink on the surface of the pigment, not the absorption volume of the voids then pigment, because of the strong absorption leads to a decrease in the degree of migration and diffusion, but with a concomitant decrease in optical density, while the strong adsorption leads to improved optical density, while increasing the degree of migration and diffusion.

The third difficulty in obtaining high quality printing is to reduce the irregularities of the printing on the final paper product. The roughness of the print is the result of the heterogeneity of the penetration of the binding is affected printing ink elements (cationic additive or pigment coating) composition for coatings in the main paper. Compositions for coatings having a low solids content, at risk, namely, that the solvent carries the binding printing ink elements from the surface of the paper during the two following phenomena: when the solvent composition is held in the main paper after coating for paper, and during further movement of the solvent to the surface of the paper during drying. Such unevenness may be limited due to the use of suspensions with high solids content, limiting the amount of solvent passing into the main paper and leaving it. However, this solids content is incompatible with some of the above tasks or theoretical solutions.

If the composition of the coating includes a pigment, the pigment suspension with a high solids content is desirable because it is known that starch binder and other additives usually added to compositions for coating universal paper are in the form of a solution with a low solids content. If the content of solid substances in suspension for coating is not maximal, dilution after adding a binder and other additives will be too significant.

The above limitations are necessary shall Timoti fixation of the dyes on the centers, evenly distributed over the surface of the paper. The obvious importance that the composition of the coating had a high solids content, however, as is known in the art, increasing the concentration of the suspensions containing aggregates, often leads to the loss of important volume of pores.

It was recognized that, as such, theoretical solve the above problems unable to solve them, on the contrary, the transfer of these problems suggests that they should be carefully weighed, and that must be found extremely difficult, if not impossible, compromises; however, they constitute one of the purposes of this invention, the essence of which is to achieve, in the end, global solutions.

The second issue of concern to specialists in this field of technology is achieving a balance with a cost-effective solution. Any expert will agree that this requirement is always a factor, greatly complicating the definition of technical solutions, especially in the area under discussion.

Known types of universal paper crackastroloka printing, characterized by surface sizing or weak as micropigmentation, is usually subjected to surface sizing or coating using the Econ is mikeski effective non-Autonomous device for coating, such as MSP or film press, provides high-speed coating and causing the coating of smaller mass than the same Autonomous system.

Varieties of special paper for crackastroloka printing are characterized by a much better print quality high resolution in comparison with universal paper. This paper is usually coated with bigger mass, using the compounds, including special high-quality binder additives, using a more expensive coating methods using, for example, a stand-alone device for coating Varibar™air scraper, watering or doctor blade.

Due to the cost of raw materials, the rate of output, weight and composition of coating, and the type of device for coating, the cost of known universal paper crackastroloka printing below the cost of matte paper high resolution for crackastroloka printing orders of magnitude, approximately in the range from 6 to 20 times. Therefore, the specialist in the art should recognize the benefits of obtaining a high-quality coatings for paper using inexpensive method.

As mentioned above, reducing the need for cationic additive to the composition for coating relatively modern special what's pigments for crackastroloka printing, is also desirable for economic reasons.

Also of interest is the reduction in the number of necessary binders, since this component is expensive part of the composition of the coating and its presence on the surface of the paper reduces the active area capable of interacting with the printing ink. One of the options includes the use of aggregates/agglomerates having a suitable small pores; in this case it is only necessary to add a sufficient amount of binder, adsorbiruyuschee on the surface of the aggregates/agglomerates, since the binder is not able to reach the surface of the primary particles within the pores. However, as indicated above, this proposal is only a theoretical one.

As for the coating process on paper, reduce its cost can be achieved by implementing a more rapid stage of drying the paper after coating. Faster drying provides a higher speed of the paper machine and its improved performance, because the risk of sticking the wet residue coating on the paper machine is reduced. More rapid drying is possible in the use of the composition for coatings with a maximum solids content is of exist.

Composition for coatings with a maximum solids content also reduces the costs associated with the transportation of the specified composition for coating from the manufacturer of the pigment to the paper mill, respectively, of the installation for coating.

The final task of the specialist in this field of technology is equal or superior performance properties (the number of sheets obtained without damage) machines for coating. It is known that such devices for coating, as MSP or film press, demonstrate superior performance properties when using suspensions for coating with a high solids content while maintaining low (from 500 to 1500 MPa*s) viscosity.

As is clear to a person skilled in the technical field, such additional technical problems require solutions. The specialist also it is clear that many of these problems require conflict or inconsistent decisions, which in the absence of proper equilibrium give rise to a difficult situation; it is, this was a difficult problem solved by this invention.

As mentioned above, common technical problem and a technical challenge is to develop a new class of pigments from RCC structured so that the s be suitable for use in the coating process on paper to get the paper which, technically speaking, is a universal coated paper, in particular, for crackastroloka printing, but printing properties which are improved compared with other coated paper of the same grade, while maintaining a low production cost.

Last but not least, this decision should, of course, be suitable for as many, if not all, types of printing devices, which eliminates another difficulty.

Any expert in the art should recognize as a commercial need for such a new technology, throw her primary technical challenge, and provide it significant technical, commercial and financial progress.

Prior art

Variants of the pigments used for the deposition of high quality coatings on paper for crackastroloka printing available on the market currently include special crassostreae pigments of the RCC, as described, for example, in EP 0815174 or expensive colloidal or precipitated silica.

It is known that in addition to its high cost as a material for coatings, silicon dioxide is usually limited to compositions for coatings low solids content, the use of which is essential what about reducing the line speed, coating, additionally, increasing the overall cost of coverage. Therefore, experts in the field of technology there is a motive to search for alternatives with a lower cost of coverage provided by the compositions with higher solids content.

According to EP 0815174, which refers to the application of RCC in the form of a coating, organophosphonate connection, such as containing amine phosphoric acid, or ethanolamine bis-(methylenephosphonate acid), is added to the PCC slurry in an amount corresponding to 0.4-0,85% wt. in the calculation of the mass of the RCC. Then the above suspension is subjected to heat aging for a sufficient period of time (from 1 to 10 hours at temperatures over 75°C, or from 2 to 5 hours at a temperature of from 80 to 85°C) to obtain the specific surface area of more than 60 m2/year

Alum or other inorganic compounds containing aluminum, can be precipitated together during the synthesis of the RCC. In example 1 of this patent, the addition of octadecahydrate of aluminum sulfate is carried out directly before the introduction of carbon dioxide. Optionally, you can also enter up to 10% wt. hydrated aluminum sulfate.

Thermal aging and/or grinding the RCC are considered important to achieve the appropriate level of binding of the printed ink with RCC.

In this invention, as will be proillyustriroval what about the below, on the contrary, do not require any costly long-term thermal aging or grinding; in fact, in the present invention thermal ageing can even lead to unacceptable loss of surface area RCC. Moreover, the content of solids in the suspension used in the examples was low, around 20%.

In EP 1246729 proposed improvement compared with the above-mentioned patent, namely, that the product obtained according to this patent, has a surface area, comprising 60-65 m2/g, preferably 80-90 m2/g, and typically not exceeding 95-100 m2/, it is Emphasized that this surface area will receive, as stated above, due to thermal aging in the presence of organophosphonates connection. It is argued that particles RCC have individual spherical shape with a diameter of approximately 0.02-0.03 µm. Such high specific surface area PCC, representing a narrow range of particle size, get in suspension with low solids content (25%).

The alleged novelty of EP 1246729 based on a combination of mostly fine RCC, having a surface area of more than 60 m2/g, and the lower part of the gel-like silicon dioxide, together with a binder.

The obtained composition can be coated using a doctor knife, or less preferably, by air scraper and trims Meier (Meyer).

The mandatory presence of expensive silicon dioxide and a low content of solids in the suspension are the main disadvantages.

In USP 5750086 describes how to obtain ultrafine particles of colloidal calcium carbonate (PCC), according to which magnesium sulfate is added to 3-14% wt. aqueous suspension of calcium hydroxide with subsequent carbonization only zinc sulfate or with sulphuric acid.

In the examples, the administered solutions of metal salts or sulfuric acid have concentration, component of 10% wt.

It is argued that this method provides for obtaining ultrafine particles of colloidal calcium carbonate with a chain structure with an average diameter of 0.01 μm or less, the average length of 0.05 μm or less and a BET specific surface 70 m2/g or more.

It is emphasized that the resulting ultrafine particles have a lower affinity for the aggregation. In fact, the applicant is primarily aimed at applications requiring non-aggregated fillers, such as plastic, which is important dispersibility of the final product. The present invention, in contrast, aims to aggregate product for crackastroloka printing on paper.

However, as indicated in the examples of patent US 575086, the specific flow rate of the gas component 120 liters per minute per kilogram of calcium hydroxide, as follows from the following, significantly higher compared with the conditions of the method according to the present invention.

In fact, according to the present invention differs from those described in the art and well-known methods, it was found that by reducing the specific velocity of the gas stream to less than about 30, or less than about 20 liters per minute per kilogram of calcium hydroxide during precipitation can be obtained not discrete pigment described in patent US 5750086, and quite large, mechanically stable porous spherical agglomerates/aggregates, consisting of the specified colloidal calcium carbonate.

As mentioned above, up until there was an opportunity to theorize about potential interest in porous RCC with a suitable distribution of pore size, possibly resulting from the sintering process, he remained theoretical until the accomplishment of the above amazing discovery. It should also be noted that in the descriptions of the known prior art, or General knowledge, there is no mention of the fact that the change in the process of obtaining the RCC one parameter among dozens will result in a porous agglomerates. Has the Xia even less evidence, such agglomerates are sustainable. And there is even less guidance on that subject to modification parameter is specified flow rate.

Described in the patent US 5750086 method was reproduced with the above decisive modification of the flow velocity and the properties of the obtained product are shown in table 2, example 1.

As follows from table 2, the product obtained by modifying the method according to patent US 5750086, according to this invention, surprisingly, is not a discrete pigment described in patent US 5750086, and a fairly large agglomerates.

However, the problem with the suspension obtained in example 1 is low solids content suitable for some applications in the respective industries, but not suitable as a coating for universal paper done on such installations, as MSP. As shown below, it is optional, requiring the solution of a problem.

Obtained the surprising result is one of the key starting points of the present invention.

Additional known methods:

In Japanese patent 2004-299302 described type ink-jet recording, comprising receiving printing ink layer, while the layer includes calcium carbonate as the main pigment, h is about reducing the level of diffusion and migration. There is no specific description of the properties or structure of the specified used calcium carbonate. Instead, the focus of this document is the use of a dispersant and a cationic charge density of such a dispersant.

In EP 0761782, Japanese patent 10-265725 and Japanese patent 2004-197055 described superior printing ink for crackastroloka printing, namely, the paint used to improve optical density, reducing their migration and/or diffusion in the printing process. None of these patents do not contain specific instructions on what pigment for coatings should be used during retrieval of a sheet of paper.

In the patent application US 2003/0227531 A1 describes a coating for paper of salts of polyvalent metal such as calcium, magnesium or aluminum, on the surface of the main paper to reduce the level of diffusion and migration.

The invention

The purpose of the present invention can be fully achieved only through a combination of a specific method of producing a porous, stable agglomerates of PCC, using a significant reduction of the flow velocity at the stage of carbonization and selected stages of increasing concentrations to obtain a suspension of PCC with a high content of solids, suitable for applying cover the Oia on paper, designed for crackastroloka printing.

It should briefly be recalled that according to the known methods of obtaining RCC usually includes the following stages: first, by blanking receive a suspension of calcium hydroxide containing about 13% solids; calcium oxide (also known as quicklime) is mixed with water in the reactor or tank for mixing. Then the above suspension of calcium hydroxide is filtered, for example, on a 100-μm filter, to remove all residual contaminants and/or directionspanel unburnt lime, and then sent to the reactor of stainless steel, equipped with a stirrer. The temperature is usually set at around 20°C, and then the slurry is directed into the reactor or tank for carbonation, where carbon dioxide is subjected to bubbling, optional air, precipitating the RCC. Suspension RCA release from the tank for carbonation after a subsequent drop in pH and/or conductivity.

The above stages are known to the person skilled in the art and in this specification as a reference included the following documents: EP 0768344, WO 98/52870 (PCT/US 98/09019) and WO 99/51691 (PCT/US 99/07233).

Generally speaking, the present invention is based on a series of first stage (stage A), leading to the receipt of the suspension RCC with low solids content, comprising essentially the porous stable agglomerates/aggregates of particles of RCC, with the consequent increase in the concentration of the specified suspension (stage) without loss of these agglomerates/aggregates.

Stage And according to this invention relate to a method for producing a porous, stable agglomerates/aggregates of RCC in the form of a suspension with a low solids content and to obtain thereby the product of the RCC, which represents a new industrial product.

Therefore, the present invention relates to a new method of obtaining suspension RCC method of carbonization, characterized in that the stage of carbonization is carried out at a strong reduction of the rate of flow of carbonizing gas to less than 30 liters per minute per kilogram of calcium hydroxide under normal conditions during deposition (stage A).

This invention also relates to a new method of obtaining suspension RCC method of carbonization, further characterized in that the receiving RCC, described in the previous paragraph, is carried out in the presence of magnesium sulfate in combination with one or more sulfates of metals II or group III, with the specified sulfate(s) of metal, has, in particular, aluminium and/or zinc, preferably, aluminium or zinc. Data stage based on the stages described in the patent US 5750086, however, as mentioned is use, with a much lower flow rate carbonizing gas.

A surprising result is that the resulting pigment is not paglalarawan, ultra-thin, microtelecom, discrete product, and represents a fairly large (from 1 to 5 μm) porous and stable agglomerates/aggregates.

The resulting agglomerates/aggregates suddenly are so stable that they essentially remain agglomerated/aggregated form during a subsequent stage of "increased concentration", and, surprisingly, the resulting agglomerates/aggregates of the RCC with the introduction of coatings for paper intended for crackastroloka printing, provide improved printing properties compared with the print quality of other types on the market of securities of the same class.

According to the most preferred options for implementation, the stage And the present invention is additionally characterized by the use of the proposed combination of magnesium sulfate and aluminum sulfate or magnesium sulfate and zinc sulfate.

According to less preferred options of implementation, the method according to the present invention used a combination of magnesium sulfate and zinc sulfate, to which add aluminum sulfate, or a combination of magnesium sulfate and aluminum sulfate, to which EXT is make zinc sulfate. In addition, less preferred implementation includes the use of magnesium sulfate and one or more sulfates of metals of group II and/or III.

In addition, this invention includes the combination of the method of receiving the RRC (stage A) with the subsequent stages of increasing concentrations (dehydration/re-dispersion) particles in the presence of a dispersant (stage).

Brand new is the use of the following combination: receiving RRC (stage A) with the process of increasing concentrations (stage) for this type crackastroloka printing.

The end product is surprisingly RCC in the form of stable agglomerates/aggregates having an average diameter in the micrometer range, namely, from 1 to 5 μm, forming the pigment of the RCC, which when used in a standard composition for coating provides excellent print quality with less cost.

This invention also relates to new pigments from RRC per se, as new industrial products, in the form of stable agglomerates/aggregates in the micrometer range, namely, from 1 to 5 μm, obtained in late stages or at the end of stages a and B. This is quite different from commercial technologies and known patents.

This invention also relates to suspensions of the new pigments containing specified the pigments as new industrial products, namely, suspensions with low solids content obtained at the end of stages A, and suspensions with high solid content, obtained at the end of stages a and B.

The invention additionally relates to new compositions for coating paper for crackastroloka printing containing these pigments or suspension of pigments.

This invention also relates to coated paper for crackastroloka printing, covered with such new formulations for coatings.

Detailed description of the invention

This invention relates to:

the method of obtaining the RCC, which can be used for different types crackastroloka printing,

- according to which a suspension of calcium hydroxide initially obtained by mixing quicklime (CaO) with water in a reactor with a stirrer or the tank ("damping"). Then a suspension of calcium hydroxide is filtered, for example, through a 100-μm filter, to remove all residual contaminants and/or directionspanel unburnt lime. Then the filtered suspension is sent to the reactor of stainless steel, equipped with a stirrer; the temperature is usually set at the level of from 10 to 70°C, after which the suspension is sent to the reactor or tank for carbonation, where bubbled through the suspension gas containing carbon dioxide. Suspension of release of b is ka, at the right time, taking into account the electrical conductivity and pH, usually when the conductivity reaches a minimum level, and pH drops below 8. Large particles are removed with a filter, such as a 45-μm filter, so that the suspension contained only ultra-thin PCC agglomerates according to the invention,

- different implementation stages of the method, including the first series of stages related to the receipt of the RCC, in which:

A1 in the above-described method of obtaining the RCC stage of carbonization is carried out at a flow rate carbonizing gas, less than 30 liters per minute per kilogram of calcium hydroxide under normal conditions during deposition.

This invention also relates to the above method, characterized in that:

A2 in the above-described method of obtaining the RCC stage A1 suspension of calcium hydroxide, leaving the specified reactor of stainless steel after the specified offices of these residual contaminants and/or directionspanel unburnt lime is treated with a combination of magnesium sulfate and the sulfates of metals of group II and/or group III, most preferably, in the presence of acid, while this acid is most preferable is a sulfuric acid, to obtain a stable, porous agglomerates/aggregates containing from 5 to 25% solids, predpochtitel is but 15 to 20% solids ("predecessor").

This invention also relates to the above method, characterized in that:

A3 in the above-described method of obtaining the RCC stages A1 or A2 suspension of calcium hydroxide initially obtained by mixing quicklime with water in a reactor with a stirrer or the tank ("damping") at a weight ratio of Cao:water of 1:3 to 1:20, preferably from 1:5 to 1:12, most preferably from 1:7 to 1:10.

This invention also relates to the above method, characterized in that:

A4 in the above-described method of obtaining the RCC stages A1, A2 or A3 temperature is preferably set in the range of 15 to 50°C, most preferably from 15 to 30°C, prior to the filing of the suspension in the reactor or tank for carbonation.

Data stage is schematically presented in the attached figure 1. On the figure references have the following meanings:

I: Water

II: quicklime

III: Reactor, such as reactor with a stirrer or tank

IV: Filter, such as a 100-μm filter

V: Residual contaminants and/or directionspoint unburnt lime

VI: Suspension of calcium hydroxide

VII: the Reactor, such as carbonizing reactor or tank

VIII: a Solution of magnesium sulfate

IX: the Sulfate(s) of metals of group II and/or group III

X: Optional acid, such as sulfuric acid

XI: Containing dioc the ID of carbon gas

XII: Filter, such as a 45-µm filter

XIII: Large particles

XIV: Suspension RCC according to this invention (in a porous, agglomerated form)

After stage And should increase the concentration of RCC received during the stage And, in the presence of cationic, anionic or combined dispersant, in a fairly mild or moderate conditions to avoid substantial destruction of aggregates/agglomerates, to achieve a concentration of from 25 to 60%, preferably in the range of from 35 to 50%, most preferably from 39 to 40% wt. solid substances. The amount of added dispersant is controlled so that only cover the agglomerates/aggregates RCC predecessor, this number corresponds to the number added to increase the viscosity of the suspension.

In that case, if the increase in concentration leads to the formation of the precipitate on the filter, such as after increasing concentration using a pressure filter or a centrifuge, or by vacuum filtration, the concentrated material is optionally washed with water and subjected to re-dispersing up until the final material essentially consists of a resilient, porous agglomerates/aggregates of the same or very close to the agglomerates/aggregates obtained in stage A.

The appreciation is the concentration can be carried out at the stage of thermal evaporation, at the end of this material has remained essentially in the form of a resilient, porous agglomerates/aggregates obtained in stage A.

Increasing the concentration of part or all of the mass of the precursor can result in a dry product, and, in this case, the dry product is subjected to the re-dispersion up until the final material essentially consists of a resilient, porous agglomerates/aggregates of the same or very close to the agglomerates/aggregates obtained in stage A.

Figure 2 presents the process of dewatering in a centrifuge including:

XXI: Suspension RCC with stages And

XXII: Dewatering centrifuge

XXIII: the Filtrate

XXIV: the Precipitate on the filter

XXV: Dispersing installation

XXVI: the Solution dispersing additives (such as sodium salt of polyacrylic acid or a mixture of sodium citrate/carboxymethylcellulose)

XXVII: Suspension RCC elevated concentrations

Figure 3 presents an alternative dewatering in a centrifuge including:

XXI: Suspension RCC with stages And

XXII: Dewatering centrifuge

XXIII: the Filtrate

XXIV: the Precipitate on the filter

XXV: Dispersing installation

XXVI: the Solution dispersing additives (such as sodium salt of polyacrylic acid or a mixture of sodium citrate/carboxymethylcellulose)

XXVII: Suspension RCC high conc the tion

Figure 4 presents stage thermal increase of concentration in vacuum, including:

XXI: Suspension RCC with stages And

XXXII: Thermal evaporator

XXIII: Suspension RCC elevated concentrations

Figure 5 presents stage heat increasing concentration on the heating plate, including:

XXI: Suspension RCC with stages And

XLII: the Heating plate

XLIII: the Solution dispersing additives (such as cationic copolymer/carboxymethylcellulose)

XXIV-Suspension RCC elevated concentrations

Described below are optional and/or preferred characteristics of the stages And implemented separately or in combination.

Speed carbonizing gas is preferably chosen in the range from 1 to 30, preferably from 10 to 20, most preferably about 19.7 liters per minute per kilogram of calcium hydroxide under normal conditions during deposition. Specified carbonizing gas is a CO2or a mixture of CO2and one or more other gases, such as air and/or nitrogen.

Suspension of calcium hydroxide is most preferable treated with a combination of magnesium sulfate and aluminum sulfate, or a combination of magnesium sulfate and zinc sulfate.

According to less preferred options, zinc sulfate may be added to the combination of magnesium sulfate and is of Ulfat aluminum, or aluminum sulfate can be added to the combination of magnesium sulfate and zinc sulfate.

Adding magnesium sulfate is most preferable to carry out the carbonation. According to a less preferred variant, the magnesium sulfate may be added or to add other sulfates, or during such addition. According to the second, less preferred variant, the magnesium sulfate may be added during the carbonization together with aluminium sulphate and/or zinc. According to the least preferred variant implementation of the invention, the magnesium sulfate may be added during the carbonization or at the beginning of carbonization.

The addition of aluminum sulfate and/or zinc sulfate is most preferable is in the process of carbonization.

Adding acid, namely, sulfuric acid, most preferably in the form of a 10% wt. solution of sulfuric acid, is preferably in the beginning of the carbonation. However, even more preferably sulfuric acid occurs simultaneously with the addition of aluminum sulfate or zinc sulfate.

Not limited to any theory, the applicant believes that the present invention is the presence, as described below, sulfuric acid necessary to achieve the desired results.

All of the above option is x sulfates of group II and/or III can be added in addition to the aluminium sulphate and/or zinc sulfate, or instead of aluminum sulfate and/or zinc sulfate.

The temperature in the tank for carbonation raise under observation up to a level in the range of 40-80°C, preferably 50-60°C, most preferably 56-57°C.

The removal of residual contaminants and/or directionspanel quicklime is done using the filter with the size of the cells constituting 45 μm, if the viscosity by Brookfield material removed from the tank for carbonation, quite low, in particular less than 100 MPa*s at 100 rpm./minutes

The final suspension of the product essentially consists of a stable porous agglomerates/aggregates.

The following features are optional and/or preferred on stages separately or in combination.

Under the terms deagglomerate/deaggregate" means that the agglomerates/aggregates obtained at the end of the stages And the specific way in accordance with this invention, decay, and the decay product is an ultra-thin RCC same type (except those contained or precipitated metal salts), as well as RCA, received in patent US '086.

Under "moderate or mild conditions" means that deagglomerate/deaggregate agglomerates/aggregates is minimized so that the agglomerates/aggregates are not "substantial destruction". More precisely,this means, most preferably, during the stages of increasing concentrations increase surface area was limited to less than 50%, preferably less than 25%, and/or an increase in the fraction of particles less than 2 microns was limited to less than 50%, preferably less than 25%, most preferably less than 10%, and/or the reduction in the average diameter of the aggregates was limited to less than 50%, preferably less than 20%, most preferably less than 15%, according to measurements carried out using the following instruments.

Image SEM (scanning electron microscopy) before and after the increase of concentration is essentially identical, which means that the present agglomerates/aggregates (such as obtained at the stage And "predecessor") does not appreciably change during the increase of concentration.

Stage increase the concentration may be in the form of either technique, thermal or mechanical separation of suspensions, provided that the aggregates/agglomerates obtained in stage A ("predecessor")that is stable and not subject to "substantial destruction" resulting from the use of this technique.

During the process of increasing concentrations of conventional dispersant added in the usual proportions to improve the content of solids in suspension without the overall increase is Ascoli suspension. The dispersant may be cationic, anionic or combination thereof. The amount of added dispersant regulate in such a way as to cover the agglomerates/aggregates RCC predecessor, this number corresponds to the number added to increase the viscosity of the suspension. For example, approximately 5-9% wt. 40% solution of sodium salt of polyacrylic acid per dry calcium carbonate is added to the suspension containing the pigment according to the invention, which corresponds to approximately 1.5 to 3.5 wt.%. dry polyacrylic acid per dry calcium carbonate.

Most preferably the concentration increase is carried out in a centrifuge or filter under pressure or by vacuum filtration or thermal concentration increases in the presence of cationic, anionic or combined dispersant. The final concentration of the suspension is about 39-40% wt. solid substances.

The degree of destruction of agglomerates/aggregates is expected. Such agglomerates/aggregates of pigment often held together by relatively weak van der Waals or electrostatic forces of attraction, overcoming the centrifugal and/or cross-efforts generated inside the equipment designed for commercial increase of concentration, and the military, within the centrifuge, rapidly rotating the decanter or filter press high pressure. So the fact that a significant destruction of agglomerates/aggregates with full achievement of the required degree of increasing concentrations is not observed, it is not completely obvious.

The present invention relates to stable, porous aggregates/agglomerates of PCC produced in the late stages only And ("predecessor"), and end-resistant, porous aggregates/agglomerates of PCC obtained by the above described methods in the late stages And in combination with the stages In which case the specified RCC acquires new properties, which, in turn, make it especially valuable for crackastroloka printing.

Stable, porous aggregates/agglomerates of PCC produced in the late stages, as well As the aggregates/agglomerates obtained after increasing the concentration of stages can be characterized by the following properties: specific surface area is from 30 to 100 m2/g, preferably from 50 to 80 m2/g, and/or the average diameter of the aggregates is from 1 to 5 μm and an average diameter of 2 μm, and/or fraction of finely divided substances smaller than 2 μm is less than 20%, preferably less than 15%, and/or the initial size of the acicular particles is from 20 to 50 nm, with a width to length ratio of the composition is AET from 1:2 to 1:10, and/or solids content, based on weight ranges from 5 to 25%, preferably 15-20% at the end of stages A, and the solids content is 25-60%, preferably 35-50% solids, in particular, 39-40% solids in the late stages Century

The final concentration of the suspension can be fully or partially obtained by adding one or more additional pigments or suspensions of pigments during stages Century

This invention relates to new pigment, characterized in that they include the described resilient, porous aggregates/agglomerates of PCC, as well as new pigment or suspensions RCC, characterized in that they include the described resilient, porous aggregates/agglomerates of PCC.

This invention also relates to new pigments, and suspensions of RCC, characterized in that the solids content in them, based on the weight ranges from 5 to 25%, preferably 15-20%solids at the end of stages A, and from 25 to 60%, preferably 35-50% solids, in particular, 39-40% solids in the late stages Century

According to a preferred variant implementation, the functional pigment or the pigment suspension with a high surface area and integrated cations introduced into the coating composition by a method known to the expert, to improve, in particular, optical the Oh density when printing without increasing the rate of migration or diffusion of the pigment, that is one of the main achievements of the present invention.

Therefore, this invention also relates to new compositions for coatings applied in the production of paper, characterized in that they include the described new aggregates/agglomerates of PCC, new pigments and/or new suspension.

This invention also relates to the described compositions for coatings, characterized in that they contained a suspension of PCC has the following properties: solids content of 25-60%, preferably 35-50%, in particular approximately 39-40% wt., and/or high surface area RCC, namely, specific surface area, comprising 30-100 m2/g, preferably 50-80 m2/year

This invention also relates to various applications of compositions for coating according to any one of p or 20 relating to the application of coatings on paper for crackastroloka printing, namely, the coating on the "generic" paper crackastroloka printing or on a special high quality paper.

In summary, the preferred invention and its the best option at present is based on the much lower flow rate carbonizing gas during deposition of the RCC; specific combinations of cations introduced into the crystal lattice of the RCC at the time what I synthesis RCC; the use of suspension for coatings with high solids content, the concentration of which increased after the synthesis of the dispersant to 25-60%, preferably up to 35-50%, in particular approximately 39-40% wt. solids; especially applicable for coating on paper on such devices for coating, as MSP or film press; the use of RCC with high surface area in the range of 30-100 m2/g, preferably 50-80 m2/g at the end of stages and/or in the late stages, most preferably at the end of the stage; the use of primary crystals RCA small diameter, agglomerated/aggregated to obtain a porous sinter RCC.

Because the surface area depends on the distribution of particle size, this distribution must be properly adjusted.

The resulting chemical surface properties of the functional pigment provide enhanced fixation contained in printing ink, dye and the increased surface area of pigment, resulting in higher optical density or reduction of cationic additives in the composition for coating which is equal to the optical density. No evidence of any increase or even lower levels of migration and/or diffusion of the pigment compared to commercial the mi alternatives.

The ability to obtain suspensions with high solids content of the pigment according to this invention provides improved performance properties when it is the introduction of the paper coating and applying the coating, such as MSP (less accumulation on the rollers MSP). High solids content reduces the energy requirements for drying, as well as more lightweight and quick drying; the speed of the paper machine can be increased without increasing deposits on the rolls in the section of the paper machine, located after drying.

This invention provides the ability to obtain suspensions with high solids content to reduce the amount of energy consumed during the stage of drying, thereby reducing the cost of production.

In addition, the use of aggregates/agglomerates according to the invention limits the amount of binder used, thereby limiting the production cost.

Since this invention prefers the agglomerates/aggregates, its application is limited to a matte paper for crackastroloka printing. The agglomerates/aggregates according to this invention are too large to obtain a glossy surface.

Various process of the present invention will become more clear after reading the following part of the description and the following non-limiting examples.

EXAMPLES

Examples get the new crackastroloka pigment and characteristics of the pigment for the respective products:

Examples 1, 5 and 7 is carried out according to the stages And the present invention. Examples 2, 3, 4, 6, 8 and 9 illustrate the increase in the concentration of the products of examples 1, 5 and 7, the concentration of which increases according to the invention (stage).

Example 1

The method according to the invention, stage And with magnesium sulfate and zinc sulfate

150 kg quicklime is added to 1300 litres of tap water in a reactor with a stirrer. Before adding lime water temperature is brought to 40°C.

Quicklime is slaked for 25 minutes with continuous stirring, and then the resulting suspension of calcium hydroxide ("milk of lime"), containing 13.1% of wt. solids, filtered through a 100 μm filter.

Precipitation of calcium carbonate is carried out in a 1000-liter cylindrical reactor made of stainless steel with an air baffles, equipped with a gas mixer and including a device for dispersing gas tube for carbonation of stainless steel for flow of gas from the carbon dioxide/air impeller, as well as probes for the regulation of the pH and conductivity of the suspension.

700 liters of a suspension of calcium hydroxide obtained in the above stage damping, add auth in the reactor for carbonation and temperature of the reaction mixture is brought to the desired initial temperature, component 20°C.

Before carbonation in lime milk is added to 30 kg of 10% wt. an aqueous solution of magnesium sulfate (MgSO4·7H2O).

Then the speed of the stirrer set at the level of about 1480./min and the suspension carbonizer, flowing a gas mixture containing 26% vol. of carbon dioxide in the air at 118 N3/hour, which corresponds to passing through the suspension of 19.7 liters per minute per kilogram of calcium hydroxide under normal conditions. During carbonization to the reaction mixture during the entire period of carbonization continuously add 100 kg of 10% aqueous solution of zinc sulfate (ZnSO4·7H2O) and 30 kg of 10% wt. an aqueous solution of sulfuric acid.

The carbonation is completed after 1 hour, 55 minutes, while the sign of its completion is the fall of conductivity to a minimum level, accompanied by a drop in pH to a constant value below 8,0.

During the carbonization temperature of the suspension to give rise due to the exothermic nature of the reaction to the final temperature of the suspension component 57°C.

Residual impurities and/or directionspanel unburnt lime is then removed, passing the aqueous suspension through a 45-µm filter.

The product of the above carbonization is a water suspension containing 15.6% of wt. solids, such as ultra-thin primary is astitsy calcium carbonate, connected together and form a stable porous spherical aggregates.

According to the SEM images, the individual crystals as components of the aggregates have a particle diameter of 20-50 nm and a width to length ratio of from 1:2 to 1:10. Also according to the SEM images, porous aggregates formed from these individual crystals have diameters of from 1 to 5 microns, the average diameter is 2 μm.

Characteristics of the pigment of the product obtained in accordance with the above method, are shown in column "Example 1" in table 2.

The table presents the results of example 1 indicate a high surface area of the aggregate/agglomerate and the corresponding sizes of aggregate/agglomerate, but the lack of solids for subsequent coating. In fact, test for coating using a composition with a low content of solid substances conducted under the General conditions described below coating, show that with the same content of solid substances on the surface of the paper coating composition with a lower solids content leads to a decrease in optical density (table 1).

Therefore, increasing the concentration should be carried out without appreciable loss or destruction of units.

Table 1
The effect of the total content of solids in suspension in 100% black optical density
The total content of solids in suspension (% wt.)The sulfate content of the metal in all solids suspensions (% wt.)View sulfate metal100% black optical density
13,710ZnSO4*7H2O2,44
36,710ZnSO4*7H2O2,72

Example 2

The method according to this invention, increasing the concentration (stage) of the product from example 1

2210 g of a suspension of precipitated calcium carbonate obtained according to the stages And the method described in example 1, cooled to 25°C and dehydrated in stages, using a filter under pressure.

Get the filter cake, containing about 43% by weight. solid substances.

The filtrate is collected and used for re-dispersion filter cake.

50 g of the filtrate obtained in the above stage of dehydration, the room is with 1-l dispersing device, equipped with the impeller, and mixed with 16 g of 40 wt.%. solution of sodium salt of polyacrylic acid as a dispersant.

In obtained in the dispersing device of the mixture with constant stirring in parts add filter sediment, residual moisture content which is 57% wt.

After each addition of filter sediment and subsequent homogenization determine the viscosity of the suspension according to Brookfield at 100 rpm./minutes Add filter cake stop, when the viscosity by Brookfield reaches a certain maximum value, which constitutes approximately 1000 MPa*S.

At this point add 680 g of filter cake.

The product of the above process of increasing concentration is the water suspension containing 39.9% of wt. solids, such as ultrafine primary particles of calcium carbonate, bound together and form a stable porous spherical aggregates ranging in size from 1 to 5 microns.

Crystal structure of the product is determined by the SEM images.

Characteristics of the pigment of the product obtained in accordance with the above method, are shown in column "Example 2" in table 2.

From the presented data it follows that the resulting pigment has a high value of specific surface BET confirming the receipt of a large power is ness, necessary for the interaction and binding printing ink, along with the corresponding aggregate sizes (from 1 to 2 μm according SEM) and the yellowing index.

In addition, the final product additionally has sufficient solids for subsequent coating on paper for crackastroloka printing.

Example 3

The method according to this invention, increasing the concentration (stage) of the product from example 1

2210 g of a suspension of precipitated calcium carbonate obtained according to the method described in example 1, cooled to 25°C and dewatered using a filter under pressure. The filtrate is collected and used for re-dispersion filter cake.

30 g of the filtrate obtained in the above stage of dehydration, placed in 1-l dispersing device, equipped with the impeller, and mixed with 6.4 g of 35 wt.%. solution of sodium citrate and 100 g 6% wt. the solution of sodium salt of carboxymethyl cellulose (CMC) as a dispersant.

In obtained in the dispersing device of the mixture with constant stirring in parts add filter sediment, residual moisture content which is 57% wt., obtained in the above stage of dehydration. After each addition of filter sediment and subsequent homogenization determine the viscosity WM is ansii according to Brookfield at 100 rpm./minutes Adding filter cake stop when the viscosity by Brookfield reaches a certain maximum value, which constitutes approximately 1000 MPa*S.

At this point add 590 g of filter cake.

The product of the above process of increasing concentration is the water suspension containing 36,1% wt. solids, such as ultrafine primary particles of calcium carbonate, bound together and form a stable porous spherical aggregates.

Crystal structure of the product is determined by the SEM images.

Characteristics of the pigment of the product obtained in accordance with the above method, are shown in column "Example 3" in table 2.

Comments to the obtained results are the same as in example 2.

Example 4

The method according to this invention, the receiving RCC (stage A, the variant with magnesium sulfate and zinc sulfate) and the increase of its concentration (stage)

150 kg quicklime is added to 1300 litres of tap water in a reactor with a stirrer. Before adding lime water temperature is brought to 40°C.

Quicklime is slaked for 25 minutes with continuous stirring, and then the resulting suspension of calcium hydroxide ("milk of lime"), containing 12.8% of wt. solids, filtered through a 100 μm filter.

Aside is their calcium carbonate is carried out in a 1000-liter cylindrical reactor made of stainless steel with chisel partitions, equipped with a gas mixer and including a device for dispersing gas tube for carbonation of stainless steel for flow of gas from the carbon dioxide/air impeller, as well as probes for the regulation of the pH and conductivity of the suspension.

700 liters of a suspension of calcium hydroxide obtained in the above stage damping, add in the reactor for carbonation and temperature of the reaction mixture is brought to the desired initial temperature, component 20°C.

Before carbonization to lime milk add 30 kg 10% wt. an aqueous solution of magnesium sulfate (MgSO4·7H2O).

Then the speed of the stirrer set at the level of about 1480./min and the suspension carbonizer, flowing a gas mixture containing 26% vol. of carbon dioxide in the air at 118 N3/hour, which corresponds to passing through the suspension of 19.7 liters per minute per kilogram of calcium hydroxide under normal conditions.

During carbonization to the reaction mixture during the entire period of carbonization continuously add 100 kg of 10% aqueous solution of zinc sulfate (ZnSO4·7H2O) and 30 kg of 10% wt. an aqueous solution of sulfuric acid.

The carbonation is completed within 1 hour and 50 minutes, while the sign of its completion is the fall of conductivity to a minimum level, followed by a drop in pH to posto is authorized values below 8,0.

During the carbonization temperature of the suspension to give rise, leading to a rise in the temperature of the final suspension to 58°C due to the heat released during the exothermic reaction.

Stage of increasing concentrations:

Then the suspension is filtered over a 45-µm filter before it is supplied to the dewatering centrifuge (operating at 4440 about./min) at a rate of 350 l/h. To filter the precipitate increased concentration discharged from dewatering centrifuges, continuous type of 4.75% wt. 40% wt. solution of sodium salt of polyacrylic acid as dispersant additives. The mixture was then re-dispersed in the device for mixing and produce a product of high concentration in the form of an aqueous suspension of pigment.

The product of the above stages of carbonization and increase the concentration is the water suspension containing 39 wt.%. solids in the form of ultrafine primary particles of calcium carbonate, connected together and form a stable porous spherical aggregates. The individual crystals as component units have a needle shape particles with a diameter of 20-50 nm and the relationship of the width to the length is from 1:2 to 1:10. Porous aggregates formed from these individual crystals have diameters comprising from 1 to 5 microns, the average diameter is 2 μm.

Crystal structure of the product is determined by the SEM images.

Characteristics of the pigment of the product obtained in accordance with the above method, are shown in column 4 in table 2.

Comments to the obtained results are the same as in examples 2 and 3.

Example 5

The method according to the invention, stage A, the variant with magnesium sulfate and aluminum sulfate

115 kg quicklime added to 1000 litres of tap water in a reactor with a stirrer. Before adding lime water temperature is brought to 40°C.

Quicklime is slaked for 25 minutes with continuous stirring, and then the resulting suspension of calcium hydroxide ("milk of lime"), containing 12.7% of wt. solids, filtered through a 100 μm filter.

Precipitation of calcium carbonate is carried out in a 1000-liter cylindrical reactor made of stainless steel with an air baffles, equipped with a gas mixer and including a device for dispersing gas tube for carbonation of stainless steel feed gas stream comprising carbon dioxide/air to the impeller, as well as probes for the regulation of the pH and conductivity of the suspension.

700 liters of a suspension of calcium hydroxide obtained in the above stage damping, add in the reactor for carbonation and temperature of the reaction mixture is brought to the desired initial temperature, component 20°C.

Before carbonization to lime milk add 30 kg 10% wt. an aqueous solution of magnesium sulfate (MgSO4·7H2O).

Then the speed of the stirrer set at the level of about 1480./min and the suspension carbonizer, flowing a gas mixture containing 26% vol. of carbon dioxide in the air at 118 N3/hour, which corresponds to passing through the suspension of 19.7 liters per minute per kilogram of calcium hydroxide under normal conditions.

During carbonization to the reaction mixture during the entire period of carbonization continuously add 100 kg of 10% wt. an aqueous solution of aluminum sulfate (Al2(SO4)3·18H2O) and 30 kg of 10% wt. an aqueous solution of sulfuric acid.

The carbonation is completed after 1 hour, 48 minutes reaction time, the sign of its completion is the fall of conductivity to a minimum level, followed by a drop in pH to a constant value below 8,0.

During the carbonization temperature of the suspension to give rise, leading to a rise in the temperature of the final suspension to 61°C due to the heat released during the exothermic reaction.

Then the suspension is filtered through a 45 μm filter and the product isolated in the form of an aqueous suspension of pigment.

The product of the above stage of carbonization is a water suspension containing 14,3% wt. solids in the form of ultra is onky primary particles of calcium carbonate, connected together and form a stable porous spherical aggregates.

The individual crystals in the form of component units have a needle shape particles with a diameter of 20-50 nm and the relationship of the width to the length is from 1:2 to 1:10.

Porous aggregates formed from these individual crystals have diameters comprising from 1 to 5 microns, the average diameter is 2 μm.

Crystal structure of the product is determined by the SEM images.

Characteristics of the pigment of the product obtained in accordance with the above method, are shown in column "Example 5" in table 2.

Example 6

The method according to this invention, increasing the concentration (stage) of the product of example 5

10 liters of a suspension of precipitated calcium carbonate, obtained as described in example 5, method, filtered through a 45-µm filter before applying thermal evaporator. The evaporator includes a cylindrical stainless steel tank equipped with a stirrer and a heating device with a double casing, working on the hot synthetic oil with a temperature of 120°C as the heating medium.

Before evaporation of 8.5% wt. 40% wt. solution of sodium salt of polyacrylic acid as a dispersant additive is added to a suspension of precipitated calcium carbonate and stirred.

Thermal behavior of the solutions of concentration reached as a result of evaporation in the specified laboratory evaporator at atmospheric pressure and the temperature of the suspension in the range of from 90 to 95°C.

The evaporation is stopped when the viscosity by Brookfield reaches its specified maximum limit of approximately 1000 MPa*S.

The product of the above process of carbonization is a water suspension containing 35,5% wt. solids in the form of ultrafine primary particles of calcium carbonate, connected together and form a stable porous spherical aggregates.

Crystal structure of the product is determined by the SEM images.

Characteristics of the pigment of the product obtained in accordance with the above method, are shown in column "Example 6 in table 2.

Example 7

The method according to the invention, stage A (an option with magnesium sulfate and zinc sulfate)

115 kg quicklime added to 1000 litres of tap water in a reactor with a stirrer. Before adding lime water temperature is brought to 40°C.

Quicklime is slaked for 25 minutes with continuous stirring, and then the resulting suspension of calcium hydroxide ("milk of lime")containing 12.5% of wt. solids, filtered through a 100 μm filter.

Precipitation of calcium carbonate is carried out in a 1000-liter cylindrical reactor made of stainless steel with an air baffles, equipped with a gas mixer and including a device for dispersing gas tube for the AC is bonisoli stainless steel feed gas stream, consisting of a carbon dioxide/air to the impeller, as well as probes for the regulation of the pH and conductivity of the suspension.

700 liters of a suspension of calcium hydroxide obtained in the above stage damping, add in the reactor for carbonation and temperature of the reaction mixture is brought to the desired initial temperature, component 20°C.

Before carbonization to lime milk add 30 kg 10% wt. an aqueous solution of magnesium sulfate (MgSO4·7H2O).

Then the speed of the stirrer set at the level of about 1480./min and the suspension carbonizer, flowing a gas mixture containing 26% vol. of carbon dioxide in the air at 118 N3/hour, which corresponds to passing through the suspension of 19.7 liters per minute per kilogram of calcium hydroxide under normal conditions.

During carbonization to the reaction mixture during the entire period of carbonization continuously add 100 kg of 10% wt. an aqueous solution of zinc sulfate (ZnSO4·7H2O) and 30 kg of 10% wt. an aqueous solution of sulfuric acid.

The carbonation is completed after 1 hour, 43 minutes reaction time, the sign of its completion is the fall of conductivity to a minimum level, followed by a drop in pH to a constant value below 8,0.

During the carbonization temperature of the suspension to give rise, which leads to the lifting tempo is atory end suspension to 62°C by the heat, released during the exothermic reaction.

Then the suspension is filtered through a 45 μm filter and the product isolated in the form of an aqueous suspension of pigment.

The product of the above stage of carbonization is a water suspension containing 13.7% of wt. solids in the form of ultrafine primary particles of calcium carbonate, connected together and form a stable porous spherical aggregates.

The individual crystals in the form of component units have a needle shape particles with a diameter of 20-50 nm and the relationship of the width to the length is from 1:2 to 1:10.

Porous aggregates formed from these individual crystals have diameters comprising from 1 to 5 microns, the average diameter is 2 μm.

Crystal structure of the product is determined by the SEM images.

Characteristics of the pigment of the product obtained in accordance with the above method, are shown in column "Example 7 in table 2.

Comments to the obtained results are the same as in example 1.

Example 8

The method according to this invention, increasing the concentration (stage) of the product of example 7

10 liters of a suspension of precipitated calcium carbonate, obtained as described in example 7 method, filtered through a 45-µm filter before it is fed into a thermal evaporator. The evaporator includes a cylindrical tank made of stainless steel, the steel soup, equipped with a stirrer and a heating device with a double casing, working on the hot synthetic oil with a temperature of 120°C as the heating medium.

Before evaporation of 8.5% wt. 40% wt. solution of sodium salt of polyacrylic acid as a dispersant additive is added to a suspension of precipitated calcium carbonate and stirred.

Heat increasing concentrations reach as a result of evaporation in the specified laboratory evaporator at atmospheric pressure and the temperature of the suspension in the range of from 90 to 95°C.

The evaporation is stopped when the viscosity by Brookfield reaches its specified maximum limit of approximately 1000 MPa*S.

The product of the above process of carbonization is a water suspension containing 36,7% wt. solids in the form of ultrafine primary particles of calcium carbonate, connected together and form a stable porous spherical aggregates.

Crystal structure of the product is determined by the SEM images.

Characteristics of the pigment of the product obtained in accordance with the above method, are shown in column "Example 8 in table 2.

Example 9

The method according to this invention, the receiving RCC (stage A, the variant with magnesium sulfate and zinc sulfate) and the increase of its concentration (the stage is)

115 kg quicklime added to 1000 litres of tap water in a reactor with a stirrer. Before adding lime water temperature is brought to 40°C.

Quicklime is slaked for 25 minutes with continuous stirring, and then the resulting suspension of calcium hydroxide ("milk of lime"), containing 13.5% of wt. solids, filtered through a 100 μm filter.

Precipitation of calcium carbonate is carried out in a 1000-liter cylindrical reactor made of stainless steel with an air baffles, equipped with a gas mixer and including a device for dispersing gas tube for carbonation of stainless steel feed gas stream comprising carbon dioxide/air to the impeller, as well as probes for the regulation of the pH and conductivity of the suspension.

700 liters of a suspension of calcium hydroxide obtained in the above stage damping, add in the reactor for carbonation and temperature of the reaction mixture is brought to the desired initial temperature, component 20°C.

Before carbonization to lime milk add 30 kg 10% wt. an aqueous solution of magnesium sulfate (MgSO4·7H2O).

Then the speed of the stirrer set at the level of about 1480./min and the suspension carbonizer, flowing a gas mixture containing 26% vol. of carbon dioxide in the air at 118 N3per hour, that is testvol passing through the suspension of 19.7 liters per minute per kilogram of calcium hydroxide under normal conditions. During carbonization to the reaction mixture during the entire period of carbonization continuously add 100 kg of 10% wt. an aqueous solution of zinc sulfate (ZnSO4·7H2O) and 30 kg of 10% wt. an aqueous solution of sulfuric acid.

The carbonation is completed in 1 hour, 44 minutes reaction time, the sign of its completion is the fall of conductivity to a minimum level, followed by a drop in pH to a constant value below 8,0.

During the carbonization temperature of the suspension to give rise, leading to a rise in the temperature of the final suspension to 56°C due to the heat released during the exothermic reaction.

Then the suspension is filtered through a 45 μm filter.

Stage of increasing concentrations:

The filtered slurry is then served with a speed of 400 l/h in dewatering centrifuge operating at 4440 about./minutes To filter the precipitate discharged from dewatering centrifuges, continuously add 6% wt. 40% wt./wt. solution of sodium salt of polyacrylic acid as dispersant additives.

The mixture is then re-dispersed in the device for mixing and produce a product of high concentration in the form of an aqueous suspension of pigment.

The product of the above stages of carbonization and increase the concentration is the water suspension containing 39.9% of wt. solid gamestv the form of ultrafine primary particles of calcium carbonate, connected together and form a stable porous spherical aggregates. The individual crystals in the form of component units have a needle shape particles with a diameter of 20-50 nm and the relationship of the width to the length is from 1:2 to 1:10. Porous aggregates formed from these individual crystals have diameters comprising from 1 to 5 microns, the average diameter is 2 μm.

Crystal structure of the product is determined by the SEM images.

Characteristics of the pigment of the product obtained in accordance with the above method, are shown in column "Example 9 in table 2.

Listed in table 2 specific surface area (SSA) was measured using the analyzer Tristar 3000, the distribution of particle size (PSD) using a Sympatec Helos, brightness using a Datacolor Elrepho 3000 Jerics, the content of solid substances using halogen scales Mettler Toledo HB43 and viscosity using Brookfield viscometer DVII in accordance with the manufacturer's recommendations.

Test coatings

Selected the above products according to this invention is administered in suspension for coating paper and put on paper.

Test coatings on the basis of the suspensions of examples 4, 6 and 8

Get three suspensions for coating on paper, each of which represents one of the three suspensions RCC, obtained according to the but to this invention, together with standard additives. Emox TSC is an oxidized potato starch from Emsland-Staerke GmbH, Basoplast PR8172 is a binder from BASF, Catiofast CS is a cationic additive Poly-Dadmac from BASF, and Lupamin 6005 is polyvinylformamide from BASF.

Table 3
The compositions of the slurries for coating (parts)
Suspension for coatingSolid content (% wt.)Suspension for coating 1Suspension for coating 2Suspension for coating 3
Suspension RCC according to this invention
Example 439,0100
Example 635,5100
Example 836,7100
Supplements
Emox TSC (Emsland-Staerke GmbH)4025
352525
Basoplast PR8172 (BASF)40101010
Catiofast CS (BASF)3310
301010
Lupamin 6005 BASF)30111
Characteristics of the final suspension for coating
The solids content in the final suspension%37,535,736,6
the pH of the final suspension-9,0 8,38,4
Viscosity according to Brookfield at 20°CMPa*s160580460

Received two additional suspensions of coatings for paper, each of which represents one of the two suspensions RCC obtained according to this invention, along with another set of standard additions (Mowiol 26-88, Printofix Cartafix VXT01 and Cartabond TS1 from Clariant).

Table 4
The compositions of the slurries for coating (parts)
Suspension for coatingSolid content (% wt.)Suspension for coating 4Suspension for coating 5
Suspension RCC according to this invention
Example 636,7100
Example 835,4100
Supplements
Mowiol 26-887,61212
Printofix43,055
Cartafix VXT0120,033
Cartabond TS143,01,51,5
Characteristics of the final suspension for coating
the pH of the final suspension-8,18,2
The solids content in the final suspension%27,827,8
The viscosity of the final slurry according to Brookfield at 20°CMPa*s300100

Then the suspension for coating 1 applied simultaneously on both sides of the main paper, is described in table 5, using Jagenberg MSP under the conditions listed in table 6.

Table 5
The main characteristics of paper, covered with a suspension for coating 1
Grams:84,1 g/m2
The content of the filler (otro):23,9%
Length of stretch:4,75 km
The contact angle with the surface OS (1σ):to 112.2
The contact angle with the surface OS (10σ):106,6
Index yellowing OS:-25,6%

Table 6
Conditions of operation of the machine for applying coatings on Jagenberg MSP using suspension for coating 1
Speed coating:560 m/min
The weight of the coating:of 9.8-10.8 g/m2
The moisture content in the coating:5,2-5,4%
Color temperature at which rite during his deposition: 28°C
Head to coverLeftRight
View rod coating:C25C25
The speed of the rod coating:200.min200.min
The pressure rod coating:1.5 bar1.5 bar
The feed rate of the pump:60.min60.min
The pressure at the feed pump:0,8 bar1.1 bar
Calendering
The number of NIPS:1
Speed calendering:200 m/min
Pressure calendering:65 kN/m
The temperature of the calendering:60°C

Suspension for p is floor 2, 3, 4 and 5 were deposited on one side of the main paper, is described in table 7, using the K-shaped device for coating under the conditions shown in table 8.

Table 7
The main characteristics of paper, covered with suspensions for coating 2, 3, 4 and 5
Grams89.2 g/m2
The content of the filler (otro)12, 9%
Length stretching5,26 km
The contact angle with the surface OS (1σ)109,3
The contact angle with the surface OS (10σ)106,4
Index yellowing OS-18,3%

Table 8
Working conditions K-shaped device for coating with grooved rod when applying suspensions for coating 2, 3, 4 and 5
The weight of the coating8 g/m2
The moisture content in the floor5%
The color temperature of the coating during application23°C
The conditions of drying paperDried in a laboratory oven at 80°C for 4 minutes

Tests crackastroloka printing

Were printed conducted tests on three different devices for crackastroloka printing, namely, Epson Stylus Photo 950, HP Deskjet 5550 and Canon i950, to compare the suitability for crackastroloka printing paper, coated pigments according to this invention, commercially available paper for crackastroloka printing. To assess the optical density and the degree of diffusion and migration were used printed cards for testing.

Paper varieties HP Bright White and Epson S041214 commercially available as a generic paper crackastroloka printing. It is believed that paper varieties Zweckform 2585 and Epson S041061 is a high quality matte paper, providing higher quality printing than the standard universal paper for crackastroloka printing.

The optical density is measured using a densitometer Gretag D 186 according to the standard procedure described by the manufacturer. The same is the number of the applied printing ink, the higher the optical density, the better the coating keeps the dyes on the surface of the paper.

The paper coated with slurry for coating 1

The next test for coatings (test for coatings 1) carry out, causing the suspension for coatings 1, which is based on suspension RCC of example 4, above the main paper.

Migration and bleed on the circuit card for testing the first type is measured using measuring equipment PapEye from ONLY Solution GmbH according to the standard procedure described by the manufacturer. The lower the resulting measurement value, the better the migration and bleed.

The above table shows that the optical density obtained by the test product according to this invention, the above optical density comparable varieties universal commercially available paper and coming close to the quality bond paper for crackastroloka printing. Migration of the pigment obtained by testing the product according to this invention, the same or lower migration other equivalent grades of commercially available paper. The level of diffusion, the resulting test the product according to this invention, below the level of diffusion of other types of commercially available paper./p>

Improved optical density, migration and bleed pigment testify to the superior balance absorption/adsorption properties compared to competing commercially available products.

In addition, the structure of the pigment does not have any negative impact on its performance characteristics; operational properties actually improved because there are fewer deposits on the MSP.

Data on the optical density of the coating according to this invention is superior to similar data comparable commercially available varieties of paper, and, in some cases, and paper for crackastroloka printing of higher quality. There is also a decrease in the level of migration of the pigment and the same rate of diffusion relative to comparable and one of the papers of higher quality.

And again, the structure of the pigment does not have any negative impact on its performance characteristics; operational properties has improved because there are fewer dry deposits on the film press.

Data on the optical density of the coating according to this invention basically superior to similar data from other comparable varieties commercially available paper and approach to data obtained in resultativity papers of the highest quality. There is a decrease in the level of migration and the same level of diffusion of the pigment relative to comparable varieties commercially available paper.

The paper coated with slurries for coating 2 and 3

Were carried out following the testing of coatings using suspensions RCC on the basis of aluminum and zinc, the concentration of which was increased thermal way. The floor of the main paper suspensions for coating 2 and 3 led, respectively, to below presents the test results of the coatings 2 and 3. To assess the optical density, the level of diffusion and migration was used the second type of cards for testing.

The level of diffusion and migration is measured using a device Personal IAS® (system for image analysis) from Quality Engineering Association, Inc., according to the standard procedure described by the manufacturer. The lower the resulting measurement value, the better the bleed and migration.

The above table shows that the optical density obtained by the test product according to this invention, the above optical density comparable varieties commercially available paper and sometimes even surpasses the data obtained in the test paper of higher quality. Migration of the pigment obtained in the test result product from the according to this invention, below are migrating other equivalent grades of commercially available paper. The level of diffusion, the resulting test the product according to this invention, below the level of diffusion of the other comparable varieties commercially available paper. The brightness of the paper is the same as the brightness of the commercially available paper.

The above table shows that the optical density obtained by the test product according to this invention, clearly above not only the optical density comparable varieties commercially available paper, but sometimes also surpasses the optical density of the paper of higher quality. Migration of the pigment obtained by testing the product according to this invention, the same or lower migration other equivalent grades of commercially available paper. The level of diffusion, the resulting test the product according to this invention, lower or the same as the level of diffusion of the other comparable varieties commercially available paper. The brightness of the paper is the same as the brightness of the commercially available paper.

The above table shows that the optical density obtained by the test product according to this invention, the above optical density CPA is accepting of varieties commercially available paper and sometimes even surpasses the optical density of the paper of higher quality. Migration of the pigment obtained by testing the product according to this invention, the same or lower migration other equivalent grades of commercially available paper. The level of diffusion, the resulting test the product according to this invention, below the level of diffusion of the other comparable varieties commercially available paper. The brightness of the paper is the same as the brightness of the commercially available paper.

The paper coated with slurries for coating 4 and 5

Were carried out following the testing of coatings using suspensions RCC on the basis of aluminium and zinc from examples 6 and 8, the concentration of which was increased thermal way. The floor of the main paper suspensions for coating 4 and 5 led, respectively, to below presents the test results of the coatings 4 and 5.

The level of diffusion and migration is measured using the second form of printed cards for testing and device Personal IAS® (system for image analysis) from Quality Engineering Association, Inc., according to the standard procedure described by the manufacturer. The lower the resulting measurement value, the better the bleed and migration.

The above table shows that the optical density obtained by the test product according to this invention, the above Opti is eskay density comparable universal varieties commercially available paper and coming close to the quality bond paper for crackastroloka printing. Migration of the pigment obtained by testing the product according to this invention, the same or lower migration other equivalent grades of commercially available paper. The level of diffusion, the resulting test the product according to this invention, below the level of diffusion of the other comparable varieties commercially available paper.

Improved optical density, migration and bleed testify to the superior balance absorption/adsorption properties of competing commercially available products.

The results of the test optical density of the product according to this invention is higher optical density comparable varieties commercially available paper, as well as higher optical density paper for crackastroloka printing of higher quality. There is also a lower level of migration and the increasing level of diffusion relative to comparable grades of paper.

The results of the test optical density of the product according to the invention is always higher than the test results of the optical density of other comparable varieties commercially available paper and draw closer to the data obtained from tests of high-quality paper grades. There is also more low the level of migration and the same rate of diffusion relative to comparable varieties commercially available paper.

The present invention also includes equivalent technical options above description and options, easy to carry out specialist after studying this proposal.

1. The way to obtain precipitated calcium carbonate (PCC), which is intended to cover paper used in ink-jet printing,
- according to which a suspension of calcium hydroxide initially obtained by mixing quicklime (CaO) with water in a reactor with a stirrer or the tank, then the suspension of calcium hydroxide is filtered, for example, through a 100-μm filter, to remove all residual contaminants and/or directionspanel unburnt lime, then filtered suspension is sent to the reactor of stainless steel, equipped with a stirrer;
the temperature is usually set at the level of from 10 to 70°C, after which the suspension is sent to the reactor or tank for carbonation, where bubbled through the suspension containing carbon dioxide gas;
the suspension is released from the tank when the conductivity reaches a minimum level, and pH drops below 8; large particles are removed through a 45-μm filter so that the suspension contained only ultra-thin PCC agglomerates according to the invention,
- different implementation stages of the method, including:
While the first stage, obtaining RCC:
A1
- one hundred is the s carbonization is carried out at a flow rate carbonizing gas, less than 30 liters per minute per kilogram of calcium hydroxide during the deposition, under normal conditions.

2. The method according to claim 1, wherein A2
- suspension of calcium hydroxide, leaving the specified reactor of stainless steel after the specified offices of these residual contaminants and/or directionspanel unburnt lime, treated with magnesium sulfate and sulfate of a metal of group II and/or group III,
most preferably in the presence of acid, while this acid is most preferable is a sulfuric acid,
- to get a stable, porous agglomerates/aggregates containing from 5 to 25% solids, preferably from 15 to 20% solids ("predecessor").

3. The method according to claim 1 or 2, characterized in that
A3
- the specified suspension of calcium hydroxide initially obtained by mixing quicklime with water in a reactor with a stirrer or the tank at a weight ratio of CaO:water of 1:3 to 1:20, preferably from 1:5 to 1:12, most preferably from 1:7 to 1:10.

4. The method according to claim 1 or 2, characterized in that
A4
the temperature is preferably set in the range of 15 to 50°C, most preferably from 15 to 30°C, prior to the filing of the suspension in the reactor or tank for carbonation.

5. The method according to claim 1, characterized in that at the point the x And perform at least one of the following:
the flow rate of carbonizing gas is preferably chosen in the range from 1 to 30, preferably from 10 to 20, most preferably about 19.7 liters per minute per kilogram of calcium hydroxide during precipitation under normal conditions,
- the specified carbonizing gas is a CO2or a mixture of CO2and one or more other gases, such as air and/or nitrogen,
- suspension of calcium hydroxide is most preferable treated with magnesium sulfate and aluminium sulfate
or magnesium sulfate and zinc sulfate.

6. The method according to claim 1, characterized in that on the stage And perform at least one of the following:
is zinc sulfate can be added to the magnesium sulfate and aluminium sulfate
the aluminum sulfate may be added to the magnesium sulfate and zinc sulfate,
- adding magnesium sulfate is most preferable to carry out carbonization,
according to a less preferred variant of magnesium sulfate can be added or to add other sulfates, or during such addition,
according to a less preferred variant magnesium sulfate may be added during the carbonization together with aluminium sulphate and/or zinc,
- magnesium sulfate may be added during the carbonization or at the beginning of carbonization,
- adding aluminum sulfate is INIA and/or zinc sulfate occurs during carbonization,
the addition of acid, in particular sulfuric acid, most preferably in the form of 10 wt.% solution H2SO4occurs at the beginning of carbonization,
most preferably, the addition of H2SO4occurs simultaneously with the addition of aluminum sulfate or zinc sulfate,
in all the above embodiments, the sulfate group II and/or III can be added in addition to the sulfates of aluminum and/or zinc or instead of sulphate of aluminium and/or zinc,
- the temperature in the tank for carbonation raise under supervision to level from 40 to 80°C, preferably from 50 to 60°C, most preferably from 56 to 57°C,
- remove residual contaminants and/or directionspanel quicklime is produced by using a filter with a mesh size of 45 μm in the case, if the viscosity by Brookfield material removed from the tank for carbonation is less than 100 MPa·s at 100 rpm,
- end suspension product essentially consists of a stable porous agglomerates/aggregates.

7. Stable, porous aggregates/agglomerates of PCC, characterized by the fact that they were obtained according to any one of claims 1 to 6.

8. Stable, porous aggregates/agglomerates of PCC, characterized in that they have the following properties:
- specific surface is from 30 to 100 m2/g, preferably from 50 to 80 m2 /g, and/or
- the average diameter of the aggregates is from 1 to 5 μm and the average diameter is 2 μm, and/or
- finely divided fraction smaller than 2 μm is less than 20%, preferably less than 15%and/or
- the initial size of the acicular particles is from 20 to 50 nm, with a width to length ratio is from 1:2 to 1:10, and/or
- the content of solids per weight is from 5 to 25%, preferably from 15 to 20%in the late stages of A.

9. Pigments, characterized in that they contain stable, porous aggregates/agglomerates of PCC according to claim 7 or 8.

10. Suspension RCC, characterized in that they contain stable, porous aggregates/agglomerates of PCC according to claim 7 or 8.

11. Suspension of PCC of claim 10, wherein the content of solid substances in them is based on the mass:
from 5 to 25%, preferably from 15 to 20%solids in the form of a "predecessor" in the late stages of A.

12. Formulations for coatings, applied in the paper industry, characterized in that they include aggregates/agglomerates of PCC, new pigments and/or new suspension according to any one of p-11.

13. Compositions for coating according to item 12, characterized in that they contained a suspension of PCC has the following properties:
the solids content of from 25 to 60%, preferably from 35 to 50%, in particular from about 3 to 40 wt.%, and/or
- specific surface area RCC is from 30 to 100 m2/g, preferably from 50 to 80 m /year

14. Applying a composition for coating according to any one of p or 13 for coating paper for crackastroloka printing.

15. Paper for crackastroloka printing, characterized in that it put at least a composition for coating according to item 12 or 13.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: titanium dioxide based pigment contains titanium dioxide particles in rutile form, having a coating. The coating contains aluminium phosphate, aluminium oxide, titanium oxide and silicon oxide. The particles are characterised by specific surface area, calculated according to a Brunauer-Emmet-Teller (BET) equation, of at least 15 m2/g. To obtain coated pigments, an aqueous suspension of uncoated titanium dioxide particles is prepared first, followed by addition of aluminium-containing and phosphorus-containing components. Further, while maintaining pH 4-9, an alkaline silicon-containing component and at least one pH regulating component, one of which is an acidic titanium-containing component, are then added. The formed suspension is then filtered, washed and dried and the precipitate is ground to obtain coated particles.

EFFECT: invention increases opacity of decorative paper.

22 cl, 5 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention can be used in production of tissue paper. Surface-treated natural calcium carbonate is used as filler in tissue paper products, where said calcium carbonate is a product of reaction of natural calcium carbonate with an acid and carbon dioxide. The carbon dioxide is formed in situ by treatment with the acid and/or is fed from an external source. The surface-treated natural calcium carbonate is obtained as an aqueous suspension having pH higher than 6.0, measured at 20°C.

EFFECT: invention improves softness of tissue paper products such as facial tissue, toilet paper, ornamental paper, towels, napkins or tissue paper cloths.

47 cl, 1 dwg, 5 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: titanium dioxide based pigment, containing titanium dioxide particles, has a coating layer containing aluminium phosphate and aluminium oxide, and said layer additionally contains hollow particles. To obtain said pigment, aqueous suspension of titanium dioxide is prepared first, and aluminium- and phosphorus-containing components are then added, after which hollow particles are added and pH of the suspension is brought to 4-9. Also, aqueous suspension of titanium dioxide can be obtained at pH not lower than 10, and aluminium- and phosphorus-containing components can then be added while maintaining pH of at least 10, after which hollow particles are added. Further, pH of the suspension is brought to 4-9 and an aluminium oxide coating is then applied at pH from 4 to 9.

EFFECT: invention increases opaqueness and retention of pigment when making decorative paper.

22 cl, 1 dwg, 1 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: invention can be used in chemical industry. The method of producing jointly ground calcium carbonate material, which contains ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC) with coefficient of curvature at least equal to approximately 30, preferably at least approximately 40 and even more preferably at least approximately 45, comprises the following steps: a) obtaining at least one calcium carbonate material, optionally, in form of an aqueous suspension; b) combined grinding of GCC and PCC, optionally, with at least another mineral material which is selected from talc, clay, Al2O3, TiO2 or mixtures thereof; c) optional sieving and/or concentration of the jointly ground calcium carbonate obtained after step (b); d) optional drying of the jointly ground calcium carbonate material obtained after step (b) or (c). The coefficient of curvature is defined as d30/d70×100, where d30 and d70 denote equivalent spherical diameters, relative which 30 wt % and 70 wt % particles have a smaller size.

EFFECT: invention enables to improve optical properties of enamel paper and exclude the PCC deagglomeration step.

40 cl, 2 tbl, 4 ex

FIELD: chemistry.

SUBSTANCE: invention can be used in chemical industry. The method of producing jointly ground calcium carbonate material, which contains ground calcium carbonate (GCC) material and precipitated calcium carbonate (PCC) comprises the following steps: a) obtaining at least one calcium carbonate material, optionally, in form of an aqueous suspension; b) combined grinding of GCC and PCC, optionally, with at least another mineral material which is selected from talc, clay, Al2O3, TiO2 or mixtures thereof; c) optional sieving and/or concentration of the jointly ground calcium carbonate obtained at step (b); d) optional drying of the jointly ground calcium carbonate material obtained at step (b) or (c). The fraction of particles of the obtained material with size smaller than 1 mcm is greater than 80%, preferably greater than 85%, more preferably greater than 90% and even more preferably greater than 95%. BET specific surface area is less than 25 m2/g.

EFFECT: invention enables to increase lustre of enamel paper.

44 cl, 2 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: suspension containing calcium carbonate is obtained by adding one or more zirconium compounds and possibly one or more other additives which do not contain phosphate, acting as a dispersant and/or an additive which assists in grinding. Calcium carbonate in dry form and/or in form of an aqueous dispersion or filtered residue is added an aqueous suspension and/or aqueous emulsion and/or aqueous solution containing one or more zirconium compounds. The zirconium compounds used is ammonium zirconium carbonate or calcium zirconium carbonate or mixture thereof.

EFFECT: invention enables to avoid the use of phosphate dispersants when preparing stable aqueous suspensions of calcium carbonate and increases content of solid substance in the suspension.

17 cl, 22 ex

FIELD: printing industry.

SUBSTANCE: to produce a precipitated calcium carbonate, a suspension of calcium hydroxide is made by mixing of quicklime with water in a reactor with a mixer or in a tank, then the produced suspension is filtered via a 100-mcm filter. The filtered suspension is sent into a reactor of stainless steel equipped with a mixer. Temperature from 10 to 70°C is set, afterwards the suspension is sent into a reactor or a tank for carbonisation, where a carbon-containing gas is bubbled through the suspension. The suspension is drained from the tank, when electric conductivity achieves the minimum level, and pH falls below 8. Coarse particles are removed at a 45-mcm filter. At the same time the carbonisation stage is carried out at speed of carbonising gas flow of below 30 litres per minute under normal conditions per kg of calcium hydroxide in process of deposition. Concentration of precipitated calcium carbonate is increased using a cationic, anionic or combined disperser under quite moderate or mild conditions, which do not cause considerable damage of aggregates/agglomerates, until concentration from 25 to 60% is achieved, preferably in the range from 35 to 50%, most preferably - from 39 to 40 wt % of hard substances.

EFFECT: invention makes it possible to produce porous stable agglomerates of precipitated calcium carbonate with size of 1-5 mcm.

22 cl, 5 dwg, 17 tbl, 9 ex

FIELD: printing industry.

SUBSTANCE: to produce a precipitated calcium carbonate, a suspension of calcium hydroxide is made by mixing of quicklime with water in a reactor with a mixer or in a tank, then the produced suspension is filtered via a 100-mcm filter. The filtered suspension is sent into a reactor of stainless steel equipped with a mixer. Temperature from 10 to 70°C is set, afterwards the suspension is sent into a reactor or a tank for carbonisation, where a carbon-containing gas is bubbled through the suspension. The suspension is drained from the tank, when electric conductivity achieves the minimum level, and pH falls below 8. Coarse particles are removed at a 45-mcm filter. At the same time the carbonisation stage is carried out at speed of carbonising gas flow of below 30 litres per minute under normal conditions per kg of calcium hydroxide in process of deposition. Concentration of precipitated calcium carbonate is increased without using an agent that promotes dispersion or with application of a cationic disperser under quite moderate or mild conditions, which do not cause considerable damage of aggregates/agglomerates, until concentration from 15 to 50% is achieved, preferably in the range from 20 to 30%, most preferably - from 23 to 26 wt % of hard substances.

EFFECT: invention makes it possible to produce porous stable agglomerates of precipitated calcium carbonate.

22 cl, 5 dwg, 9 tbl, 12 ex

FIELD: textile fabrics, paper.

SUBSTANCE: method is related to production of coated paper or cardboard. Method includes application of pigment composition as coating on at least one side of paper or cardboard web. Specified pigment composition is water dispersion, which includes optionally aggregated colloidal particles of silicon dioxide or aluminium silicate as pigment particles, which are prepared from alkali metal silicate by ion exchange or pH reduction and having surface area of approximately from 30 m2/g to approximately 450 m2/g. Coating contains also at least one cationic component selected from group that consists of water-soluble aluminium salts and cationic polymers with molecular weight from approximately 2,000 to approximately 1,000,000 and charge density from approximately 0.2 mEq/g to approximately 12 mEq/g, in which at least approximately 0.4 g of pigment particles from pigment composition is applied on m2 of coated side of paper or cardboard web. Invention is also related to paper or cardboard produced by this method. It is also related to composition of above mentioned pigment in the form of water dispersion, which includes less than approximately 3 wt % of organic binders and to method of above mentioned pigment composition production, in which mixing is done to produce water dispersion in order to avoid gel formation and deposition.

EFFECT: improvement of printing and strength properties of coating, and also lower scuffing of paper.

26 cl, 5 tbl, 4 ex

FIELD: textiles; paper.

SUBSTANCE: composition is designed for refining fibrous material, can be used in the production of enamelled cardboard and paper and relates to the cellulose-paper industry. The composition contains a modified pigment and a water soluble binding substance. The pigment is calcium sulfoaluminate, modified starch or polyvinyl alcohol with mass ratio content of 0.5-1.5. The water soluble binding substance is starch.

EFFECT: resistance to fluffing and whiteness of the coating with considerable lowering of consumption of the binding substance when making the composition.

1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to organic fibres having a mineralised surface, which includes organic fibres having a length in the millimetre range, the surface of which is at least partially coated with finely dispersed nanoparticles alkali-earth metal carbonates using binding materials based on copolymers which contain, as monomers, one or more dicarboxylic acids or one or more monomers from a group of diamines, triamines, dialkanolamines or trialkanolamines, and epichlorohydrin, a method of producing such organic fibres having a mineralised surface, aqueous suspensions thereof, use thereof in paper production, in finishing paper surfaces, plastic surfaces, cement and clay, in paint and lacquer, and use of binding substances according to the present invention to coat organic fibres with nanoparticles of alkali metal carbonates.

EFFECT: providing fibre-pigment or filler composites, as well as aqueous suspensions thereof, which not only have good optical properties and good printing properties, but also have an insignificant or no tendency to segregate in treatment conditions thereof, and also enable to obtain paper or cardboard having high content of filler of nanoparticles which are otherwise hard to hold due to their fineness.

37 cl, 8 tbl, 13 dwg

FIELD: textiles, paper.

SUBSTANCE: paper base is intended for internal and external sizing, which has high dimensional stability, and can be used in pulp and paper industry. Paper base contains cellulose fibers, at least one filler, and sizing agent. At that the paper base has a coefficient of hygroextension from 0.6 to 1.5%. The Scott internal constraint in the transverse direction is not greater than 300 J/m2, and/or Scott internal constraint in the longitudinal direction is not greater than 300 J/m2. Also a method of manufacturing the paper base and versions of paper base are proposed.

EFFECT: increased dimensional stability and durability of the surface of the paper base.

26 cl, 24 dwg, 15 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: invention can be used in making paper products. The gypsum product essentially consists of undamaged crystals, having weight-average diameter D50 0.1 - 2.0 mcm and particle size distribution width less than 2.0. The shape factor of the crystals is equal to at least 2.0 and the aspect ratio is equal to 1.0-10. The gypsum product is obtained by reacting calcium sulphate hemihydrate and/or calcium sulphate anhydrite and water in the presence of a crystal habit modifier. The reaction mixture has dry substance content of 50-84 wt %. The crystal habit modifier is used in amount of 0.01-5.0% of the weight of the calcium sulphate hemihydrate and/or calcium sulpohate anhydrite and is selected from a group consisting of ethylenediamine succinic acid, iminodisuccinic acid, ethylenediamine tetraacetic acid, diethylenetriamine pentaacetic acid, nitrilotriacetic acid, N-bis-(2-(1,2-dicarboxyethoxy)ethylasparticacid, di-, tetra- and hexaaminostilbene sulphonic acid and salts thereof, such as sodium aminotriethoxy succinate (Na6-TCA), as well as alkylbenzene sulphonates. The crystallised or extracted gypsum is dispersed, treated with biocides, sieved and bleached.

EFFECT: high lustre and opacity due to that the gypsum particles are flat and have equal size.

18 cl, 11 dwg, 5 ex

FIELD: chemistry.

SUBSTANCE: mixture is prepared from calcium sulphate semihydrate and/or calcium sulphate anhydrite and water with dry substance content of said mixture ranging from 34 to 84 wt %. The mixture is stirred until formation of a crystalline gypsum product. The reaction mixture can further be mixed with a calcium sulphate dihydrate or a crystal habit modifier selected from ethylene diamine amber acid, amino diamber acid, ethylene diamine tetraacetic acid, diethylene triamine pentaacetic acid, nitrilotriacetic acid, N-bis-(2-(1,2-dicarboxyethoxy)ethylaspartic acid, di-tetra- and hexaaminostilbene sulphonic acid and salts thereof, such as sodium aminotriethoxy succinate (Na6-TCA), as well as akylbenzene sulphonates. Water is used at temperature 0-100°C. Crystallised gypsum is dispersed using a dispersant in amount of 0.01-5.0 wt %, treated with a biocide, sieved and bleached. The obtained gypsum product essentially consists of intact gypsum crystals with size 0.1-2.0 mcm, shape factor 2.0-5.0 and aspect ratio 1.0-10.

EFFECT: simple method.

23 cl, 33 dwg, 28 ex

FIELD: textiles, paper.

SUBSTANCE: composition comprises: a) a filler, b) a cationic inorganic compound - polyaluminumchloride, c) a cationic organic compound, and d) anionic polysaccharide. The filler is present in an amount of at least about 1% by weight, based on the total weight of the composition. Anionic polysaccharide is present in an amount from about 1 to about 100 kg/ton based on the weight of the filler. The composition is substantially free of fibers. Filler composition of the version contains the components a), b), c) and d), as defined above. The only difference is that the component c) is a cationic polyamine condensation polymer, and the component d) has a degree of substitution of stoichiometrically excess anionic groups of up to about 0.65. At that each of b) and c) components present in an amount from about 0 to about 30 kg/ton based on the weight of the filler. At that the composition comprises at least one of b) and c) components. Methods of obtaining compositions of filler comprise mixing a), b), c) and d), as defined above. The invention also relates to a filler composition, which is obtained by this method, an application of the filler composition as an additive to an aqueous suspension of cellulose in the production process of paper and to manufacturing paper comprising adding a filler composition to an aqueous suspension of cellulose. The invention also relates to a paper obtained with this method, and paper comprising the filler composition.

EFFECT: improvement of composition.

35 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: suspension containing calcium carbonate is obtained by adding one or more zirconium compounds and possibly one or more other additives which do not contain phosphate, acting as a dispersant and/or an additive which assists in grinding. Calcium carbonate in dry form and/or in form of an aqueous dispersion or filtered residue is added an aqueous suspension and/or aqueous emulsion and/or aqueous solution containing one or more zirconium compounds. The zirconium compounds used is ammonium zirconium carbonate or calcium zirconium carbonate or mixture thereof.

EFFECT: invention enables to avoid the use of phosphate dispersants when preparing stable aqueous suspensions of calcium carbonate and increases content of solid substance in the suspension.

17 cl, 22 ex

FIELD: printing industry.

SUBSTANCE: to produce a precipitated calcium carbonate, a suspension of calcium hydroxide is made by mixing of quicklime with water in a reactor with a mixer or in a tank, then the produced suspension is filtered via a 100-mcm filter. The filtered suspension is sent into a reactor of stainless steel equipped with a mixer. Temperature from 10 to 70°C is set, afterwards the suspension is sent into a reactor or a tank for carbonisation, where a carbon-containing gas is bubbled through the suspension. The suspension is drained from the tank, when electric conductivity achieves the minimum level, and pH falls below 8. Coarse particles are removed at a 45-mcm filter. At the same time the carbonisation stage is carried out at speed of carbonising gas flow of below 30 litres per minute under normal conditions per kg of calcium hydroxide in process of deposition. Concentration of precipitated calcium carbonate is increased using a cationic, anionic or combined disperser under quite moderate or mild conditions, which do not cause considerable damage of aggregates/agglomerates, until concentration from 25 to 60% is achieved, preferably in the range from 35 to 50%, most preferably - from 39 to 40 wt % of hard substances.

EFFECT: invention makes it possible to produce porous stable agglomerates of precipitated calcium carbonate with size of 1-5 mcm.

22 cl, 5 dwg, 17 tbl, 9 ex

FIELD: printing industry.

SUBSTANCE: to produce a precipitated calcium carbonate, a suspension of calcium hydroxide is made by mixing of quicklime with water in a reactor with a mixer or in a tank, then the produced suspension is filtered via a 100-mcm filter. The filtered suspension is sent into a reactor of stainless steel equipped with a mixer. Temperature from 10 to 70°C is set, afterwards the suspension is sent into a reactor or a tank for carbonisation, where a carbon-containing gas is bubbled through the suspension. The suspension is drained from the tank, when electric conductivity achieves the minimum level, and pH falls below 8. Coarse particles are removed at a 45-mcm filter. At the same time the carbonisation stage is carried out at speed of carbonising gas flow of below 30 litres per minute under normal conditions per kg of calcium hydroxide in process of deposition. Concentration of precipitated calcium carbonate is increased without using an agent that promotes dispersion or with application of a cationic disperser under quite moderate or mild conditions, which do not cause considerable damage of aggregates/agglomerates, until concentration from 15 to 50% is achieved, preferably in the range from 20 to 30%, most preferably - from 23 to 26 wt % of hard substances.

EFFECT: invention makes it possible to produce porous stable agglomerates of precipitated calcium carbonate.

22 cl, 5 dwg, 9 tbl, 12 ex

FIELD: textile, paper.

SUBSTANCE: method includes provision of a thick mixture of cellulose suspension, which contains a filler. The thick suspension mass is dissolved to form a diluted mix of suspension, in which the filler is available in amount of at least 10 wt % in terms of dry mass of dissolved suspension mix. The thick mixture of suspension and/or dissolved mix are flocculated. Polymer system of retention/dehydration is used in flocculation. The dissolved mixture of suspension is dehydrated on a mesh to form a sheet, and then the sheet is dried. In this method the polymer system of retention/dehydration contains the following: i) a water-soluble branched anion-active polymer and ii) a water-soluble cation-active or amphoteric polymer. The anion-active polymer is available in the thick mixture or in the dissolved mixture of suspension prior to addition of cation-active or amphoteric polymer.

EFFECT: improved retention of ash relative to complete retention with higher quality of paper.

16 cl, 21 dwg, 32 tbl, 8 ex

FIELD: textile, paper.

SUBSTANCE: method includes provision of a thick mixture of suspension, which contains wood mass and a filler. The thick suspension mix is dissolved to form a diluted mix of suspension, in which the filler is available in amount of at least 10 wt % in terms of dry mass of dissolved suspension mix. The thick mix and/or dissolved mix of the suspension are flocculated, using a polymer system of retention/dehydration. The dissolved mixture of suspension is dehydrated on a sieve to form a sheet, and then the sheet is dried. The polymer system of retention/dehydration contains the following: i) a water-soluble branched anion-active polymer and ii) a water-soluble cation-active or amphoteric polymer. The method may be realised on paper-making machines of quick dehydration, such as GAP former.

EFFECT: improved retention of ash with reduction of dehydration.

16 cl, 26 dwg, 46 tbl, 16 ex

FIELD: chemistry.

SUBSTANCE: invention can be used in production of tissue paper. Surface-treated natural calcium carbonate is used as filler in tissue paper products, where said calcium carbonate is a product of reaction of natural calcium carbonate with an acid and carbon dioxide. The carbon dioxide is formed in situ by treatment with the acid and/or is fed from an external source. The surface-treated natural calcium carbonate is obtained as an aqueous suspension having pH higher than 6.0, measured at 20°C.

EFFECT: invention improves softness of tissue paper products such as facial tissue, toilet paper, ornamental paper, towels, napkins or tissue paper cloths.

47 cl, 1 dwg, 5 tbl, 3 ex

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