Paper and cardboard manufacture process

FIELD: paper-and-pulp industry.

SUBSTANCE: process comprises preparation of paper pulp, flocculation of pulp, drainage of pulp on the screen to form sheet, and subsequent drying of sheet. Flocculation involves flocculation system including water-soluble anionic branched polymer and silicon-containing material. Polymer is prepared using water-soluble anionic ethylenically-unsaturated monomer or monomer mixture and ramification-forming agent. Polymer is characterized by intrinsic viscosity above 1.5 dl/g and/or Brookfield viscosity in salt solution above about 2.0 mPa·s, rheological oscillation delta tangent value at 0.005 Hz above 0.7, and/or reduced viscosity in deionized water at least thrice exceeding reduced viscosity in salt solution of corresponding nonbranched polymer obtained in absence of ramification-forming agent.

EFFECT: improved drainage, retention, and formation process.

14 cl, 1 dwg, 6 tbl, 6 ex

 

The present invention relates to a method of manufacture of paper and paperboard from pulp of fibrous masses using the new floculants system.

During the manufacture of paper and cardboard pulp and liquid fibrous mass drain on a movable grid (often called grid paper machine for casting sheet, which is then dried. It is well known adding to the pulp slurry a water-soluble polymer to cause the effect flocculation of the pulp solids and improve drainage on a movable grid.

To produce more paper many modern paper machines operate with higher speeds. Due to the higher speed machines pay much attention to the drainage systems and retention, which provide enhanced drainage. However, it is known that increasing the molecular weight polymer additives that promote the retention, which is injected directly before drainage, accompanied by a tendency to increase the rate of drainage, but does harm to the molding. Achieving an optimal balance of retention, drainage, drying and molding by adding a single polymer additives that promote the retention, involves problems of a technological nature, so common practice is the fast sequential addition of two separate materials.

In EP-A 235893 is proposed a method in which at the stage of exposure to shear stress in the fiber for making paper introduced almost linear water-soluble cationic polymer, and then, after this stage, the impact of shear force, produce re-flocculation by the addition of bentonite. The implementation of this method provides the possibility of improved drainage, and good molding and retention. This method, which has found industrial embodiment of the firm Ciba Specialty Chemicals in the form of technology under the trademark Hydrocol®confirms its effectiveness for more than a decade.

Were later made various attempts to develop variants of this method by making small modifications in one or more components.

In the US 5393381 described a method of manufacturing paper or cardboard, in which a suspension of the fibers of the fibrous mass of the added water-soluble branched cationic polyacrylamide and bentonite. This branched cationic polyacrylamide is prepared by polymerization in solution of a mixture of acrylamide, cationic monomer, agent education branches and regulator polymerization degree.

In the US 5882525 described method in which a dispersion of suspended solids, for example in balochista the pulp for making paper, to release water type cationic branched water-soluble polymer, the solubility of which is greater than about 30%. This cationic branched water-soluble polymer prepared from the same components as those described in US 5393381, i.e. by polymerization of a mixture of acrylamide, cationic monomer, agent education branches and regulator polymerization degree.

In WO 98/29604 described method of making paper, in which the pulp suspension to form flakes add cationic polymer additive that promotes retention, these flakes are subjected to mechanical failure, and then re flocculation of the suspension by adding a solution of the second anionic polymer additives that promote retention. This anionic polymer additive that promotes retention, is a branched polymer, which is characterized as having a rheological oscillation value of tan Delta at 0.005 Hz 0.7 or more with the above viscosity TLU (viscometer with a suspended level) in deionized water, which is at least three times shows the viscosity of the TLU in the salt solution of the respective polymer obtained in the absence of the agent education branches. In comparison with method and, previously developed in the art, the implementation of this method leads to a noticeable improvement in the combination of retention and formation.

In EP-A 308752 described method of making paper, in which the composition of the paper add low molecular weight cationic organic polymer, and then the colloidal silica and high molecular weight charged acrylamide copolymer with a molecular weight of at least 500000. In the description of these high molecular weight polymers indicated that they are linear polymers.

However, there is still a need for further improvement of the methods of making paper by further improving the drainage, retention and molding process. Moreover, there is also a need to create more effective floculants system for making paper with high filler contents.

In accordance with this invention features a method of making paper or paperboard comprising preparing a pulp suspension, flocculation of the suspension, draining the suspension on the grid casting sheet and the subsequent drying of the sheet, characterized in that the suspension localroot using floculants system that includes a silicon-containing material and the anionic branched water-soluble polymer which is produced using a water-soluble ethylene-unsaturated anionic monomer or monomer mixture and agent education branches, moreover, this polymer has

(a) the characteristic viscosity of more than 1.5 DL/g and/or viscosity by Brookfield in saline solution of more than about 2.0 MPa·C;

(b) rheological oscillation value of tan Delta at 0.005 Hz more than 0.7 and/or

(a) shows the viscosity of the TLU in deionized water, which is at least three times shows the viscosity of the TLU in the salt solution of the corresponding unbranched polymer obtained in the absence of the agent, the formation of branches.

It was found that the flocculation of pulp suspensions using floculants system that includes a silicon-containing material and the anionic branched water-soluble polymer with special rheological characteristics, provides improved retention, drainage and formation in comparison with the results of the application of the anionic branched polymer in the absence of silicon-containing material, or silicon-containing material in the absence of the anionic branched polymer.

Silicon-containing material may be any of the materials selected from the group comprising particles on kremmidiotis basis, kremmidiotis the microgels, colloidal silica, colloidal solution of silicic acid, silica gels, polysilicates, aluminosilicates, pollum the silicates, borosilicate, polymorbidity and zeolites. Silicon-containing material can be in the form of anionic material of the microparticles. Alternatively silicon-containing material may be cationic silicon dioxide.

Suitable silicon-containing material may be selected from silica and polysilicates. This silica can be, in particular, any colloidal silica, such as that described in WO 86/00100. The polysilicate may be colloidal silicic acid, which is described in US 4388150.

Polysilicate according to the invention can be obtained by acidification of an aqueous solution of alkali metal silicate. So, for example, polysilicon microgels, otherwise known as active silica can be obtained partial acidification of the alkali metal silicate to a pH of about 8-9 using mineral acids or acidic ion-exchange resins, acidic salts and acidic gases. It may be necessary sufficient aging freshly polysilicon acid to provide the opportunity for the formation of three-dimensional structures. Usually the time of aging is not enough to go polysilicon acid in the gel. Especially preferred silicon-containing materials include polyaluminosilicate. Polyaluminosilicate can serve, for example the EP, aluminized polysilicon acid is prepared by first obtaining microparticles polysilicon acid, and then followed by treatment with aluminum salts, for example as set forth US 5176891. Such polyaluminosilicate consist of silicon microparticles with aluminum, are mainly located in the surface area.

In another embodiment, polyaluminosilicate can be polyparticulate polysilicon microgels with a specific surface area greater than 1000 m2/g, prepared by the reaction of alkali metal silicate with an acid and a water-soluble aluminum salts, for example as described in US 5482693. The molar ratio of the aluminum oxide/silicon dioxide in polyaluminosilicate typically is in the range from 1:10 to 1:1500.

Polyaluminosilicate can be obtained by acidification of an aqueous solution of alkali metal silicate to a pH of 9 or 10 using concentrated sulfuric acid, containing from 1.5 to 2.0 wt.% water-soluble aluminum salts such as aluminum sulfate. This aqueous solution can be subjected to sufficient aging for the formation of three-dimensional structure of the microgel. As a rule, polyaluminosilicate subjected to aging for up to about two and a half hours before dilution with aqueous polysilicate until the content of silicon dioxide of 0.5 wt.%.

Silicone material can with with colloidal borosilicate, for example, such as described in WO 99/16708. Colloidal borosilicate can be prepared by introducing a dilute aqueous solution of alkali metal silicate in contact with the cation exchange resin to obtain silicic acid, and then obtaining the target product by mixing a dilute aqueous solution of a borate of an alkali metal hydroxide alkali metal, resulting in an aqueous solution containing from 0.01 to 30% In2About3the pH value of which ranges from 7 to 10.5.

Anionic branched polymer is prepared from a water-soluble monomer mixture comprising at least one anionic or potentially anionic ethylene-unsaturated monomer and a small amount of agent education branches, for example as described in WO 98/29604. Usually this polymer is produced from a mixture of from 5 to 100 wt.% anionic water-soluble monomer and from 0 to 95 wt.% nonionic water-soluble monomer.

The solubility of water-soluble monomers, typically, is at least 5 g/100 cubic cm Preferred anionic monomer chosen from the group comprising acrylic acid, methacrylic acid, maleic acid, crotonic acid, taconova acid, 2-acrylamide-2-methylpropanesulfonic acid, arylsulfonate acid, vinylsulfonate Ki the lot and their salts of alkali metals and ammonium. Preferred nonionic monomer chosen from the group comprising acrylamide, methacrylamide, N-vinyl pyrrolidone and hydroxyethylacrylate. Particularly preferred Monomeric mixture comprises acrylamide and sodium acrylate.

As agent for the formation of branches can be used any chemical material which causes the formation of branches in the reaction via carboxyl or other side groups (e.g., epoxy, silane, containing polyvalent metals or formaldehyde). The preferred agent is the formation of branches is polyethylene-unsaturated monomer, which is injected in the monomer mixture from which the polymer. The required number of agent education branches usually vary depending on the specific agent used in the formation of branches. For example, when using polyethylene-unsaturated acrylic agents of education branches, such as methylenebisacrylamide, their molar amount is usually less than 30 molar frequent./million, and preferably less than 20 ppm million it is Usually less than 10 ppm million, and most preferably less than 5 ppm million Preferred optimal number of agent education branches ranges from about 0.5 to 3 or 3.5 molar frequent./million or even 3,8 frequent./million, but some is, some cases may require the use of 7 or 10 ppm million The preferred agent education branches soluble in water. As it is, as a rule, can be used bifunctional material, such as methylenebisacrylamide, or it can be trifunctionally, tetrafunctional or cross-linking agent of higher functionality, such as tetraalkylammonium. Since the allyl monomer typical low constant copolymerization, it usually enters into the polymerization with a lower speed, so when using polyethylene-unsaturated allyl agents of education branches, such as tetraalkylammonium, traditional practice is adding them in higher concentrations, for example from 5 to 30 or even 35 molar frequent./million, or 38 ppm million or even up to 70 or 100 frequent./million

It may also be desirable inclusion in the monomer mixture control degree of polymerization. When you add a controller to the degree of polymerization, it can be used in amounts of at least 2 miscast./million and you can also enter up to 200 miscast./million Typical number of control degrees of polymerization can be in the range from 10 to 50 miscast./million as a regulator of the degree of polymerization can be used any acceptable chemical substance, such as hypophosphite sodium, 2-mercap aethanol, malic acid or thioglycolate acid. However, in the preferred embodiment, anionic branched polymer prepared without adding controller polymerization degree.

Anionic branched polymer is usually in the form of an emulsion or dispersion of water in oil. Such polymers are generally produced by polymerization in emulsion with reversed phase to prepare an emulsion with reversed phase. The size of at least 95 wt.% particles of this product is usually less than 10 microns, and preferably at least 90 wt.% - less than 2 μm, such as being greater than 100 nm, and most essentially in the range from 500 nm to 1 μm. Such polymers can be obtained by conventional methods of emulsion or microemulsion polymerization with reversed phase.

The value of tan Delta at 0.005 Hz determined using a viscometer with adjustable voltage by oscillation method in an aqueous solution of the polymer in deionized water at a concentration of 1.5 wt.% after processing in the dryer for two hours. During this work used the device Carried CSR 100, equipped with a 6-inch acrylic cone with a cone angle of 1°58’ and value of pacenote 58 μm (product marked with the position 5664). The used sample is approximately 2 to 3 cubic cm With plate Sang the Thiey the temperature of the support at the level of 20.0±0,1° C. In the range of sweep from 0,005 to 1 Hz in 12 steps on a logarithmic basis of the applied angular offset 5×10-4radians. The results of the determination of G’ and G’ are recorded and used to calculate values of tan Delta (G’/G’). The value of tan Delta is the ratio between the loss modulus (viscous) G and the dynamic modulus of elasticity (storage modulus G’ within the system.

Suppose that at low frequencies (0.005 Hz) the rate of deformation of the sample is sufficiently low for it to have a linear or branched intertwined chains had the opportunity to untwisting. Mesh or cross stitched systems are characterized by a constant tangle of chains and exhibit low values of tan Delta in the whole wide frequency range. Thus, for okharakterizovanie properties of polymers in the aquatic environment are resorting to low-frequency (e.g., 0.005 Hz) measurements.

The value of tan Delta anionic branched polymer at 0.005 Hz should exceed 0.7. The value of tan Delta preferred anionic branched polymer at 0.005 Hz to 0.8. In a preferred embodiment, the characteristic viscosity of at least 2 DL/g, for example at least 4 DL/g, in particular at least 5 or 6 DL/g May need to obtain significant is considerable more high molecular weight polymers, which are characteristic viscosity, reaching 16 or 18 DL/g, However, the characteristic viscosity of the preferred polymers is in the range from 7 to 12 DL/g, mainly from 8 to 10 DL/g

Preferred branched anionic polymer can also be characterized in comparison with the corresponding polymer obtained under the same polymerization conditions but in the absence of the agent education branches (i.e., "non-branched polymer"). Characteristic viscosity unbranched polymer is usually at least 6 DL/g, and preferably at least 8 DL/g Often it is from 16 to 30 DL/g Agent education branches are usually used in an amount such that the reduction of the characteristic viscosity relative to its original value (expressed in DL/g) in the above unbranched polymer ranged from 10 to 70%, and sometimes up to 90%. The viscosity of polymers in Brookfield salt solution is determined by preparation of an aqueous solution concentration of 0.1 wt.% polymer (basic substance) in 1 M aqueous solution of NaCl at 25°using a Brookfield viscometer equipped with a UL console at 6 Rev/min Thus, the powdered polymer or a polymer obtained by polymerization with reversed phase, obligatory dissolved in deionized the Oh water to obtain a concentrated solution and the concentrated solution was diluted with 1 M aqueous NaCl. Typically, the viscosity of the salt solution exceeds 2.0 MPa·and, as a rule, is at least about 2.2, and preferably at least 2.5 MPa·C. Usually it is not more than 5 MPa·and the values from 3 to 4, usually preferred. All the measurements were carried out at a speed of 60 Rev/min

Values are given viscosity at TLU used to okharakterizovanie anionic branched polymer, determined at 25°using glass viscometer with a suspended level, and suitable viscometer is chosen so that it matches the viscosity of the solution. Given the viscosity calculated according to the formula η-η00where η and η0indicate the results of determination of viscosity, respectively, of aqueous solutions of polymers and empty solvent. It can also be called as the specific viscosity. Given the strength of the CPG in deionized water represents the number obtained for a 0.05%aqueous solution of the polymer prepared in deionized water. Given the strength of the CPG in saline solution represents a number obtained for a 0.05%aqueous solution of the polymer prepared in 1 M sodium chloride.

The preferred value of a given viscosity at TLU in deionized water is at least 3, and usually ENISA least 4, for example, up to 7, 8 or more. The best results are achieved when it exceeds 5. In the preferred embodiment, it is higher than the viscosity in the TLU in deionized water at an unbranched polymer, i.e. in other words, the polymer obtained in the same polymerization conditions but in the absence of the agent education branches (and, hence, have a higher characteristic viscosity). If the viscosity of the TLU in deionized water does not exceed the given viscosity TLU deionized water is an unbranched polymer, in a preferred embodiment, it comprises at Pere 50%, and typically at least 75%, reduced viscosity TLU deionized water is an unbranched polymer. Given the strength of the CPG in saline solution is usually less than 1. Given the viscosity of the TLU deionized water is often at least five times and preferably at least eight times exceeds a given viscosity at TLU in saline solution.

In accordance with the invention, components floculants system can be combined into a mixture and put in the pulp suspension in the form of a single composition. According to another variant of the anionic branched polymer and the silicon-containing material can be entered separately, but at the same time. However, preferred is the preliminary version of the silicon-containing material and the anionic branched polymer added sequentially, in a more preferred embodiment, after the introduction of the silicon-containing material in suspension type anionic branched polymer.

In a preferred embodiment, a water-soluble anionic branched polymer and the silicon-containing material is introduced into the pulp suspension, which is pre-treated with a cationic material. Such pre-processing cationic material can be accomplished by the introduction of cationic materials in suspension at any point up to the point of adding the anionic branched polymer and the silicon-containing material. Thus, the processing of cationic material can be produced directly before adding the anionic branched polymer and the silicon-containing material, although in the preferred embodiment, the cationic material is introduced into the suspension early enough for the purpose of its distribution in the entire volume of the pulp suspension before adding or anionic branched polymer, or silicon-containing material. It may be necessary to add a cationic material in front of one of the stages of mixing, sorting and cleaning of the masses, and in some cases before dilution of the suspension of the fibrous mass. It can be appropriate to even add the effect of cationic material in the mixing pool or mixer, or even one or more components of the pulp suspension, for example in suspension of waste paper with a coating or filler, in particular in the sludge precipitated calcium carbonate.

As the cationic material may be used any of a number of cationic products such as water-soluble cationic organic polymers and inorganic materials, such as alum, polyaluminium, the trihydrate of aluminofluoride and alamoflorida. Water-soluble cationic organic polymers can serve as natural polymers, such as cationic starch, and synthetic cationic polymers. Particularly preferred cationic materials which are coagulated or localroot cellulose fibers and other components of the pulp suspension.

In accordance with another preferred object of the invention florulenta the system includes at least three floculant component. Thus, this preferred system used water-soluble branched anionic polymer, silicon-containing material and at least one additional flocculant/coagulant.

In a preferred embodiment, additional flatulently/coagulants component add before the introduction of either silicon-containing material, labourinaction branched polymer. As an additional flocculant, as a rule, use a natural or synthetic polymer or other material capable of causing flocculation/coagulation of the fibers and other components of the pulp suspension. This additional flocculant/coagulant can serve as cationic, nonionic, anionic or amphoteric natural or synthetic polymer. It can be a natural polymer, such as natural starch, cationic starch, anionic starch or amphoteric starch. Alternatively it may be any water-soluble synthetic polymer, which preferably exhibits ionic properties. Preferred ionic water-soluble polymers have a cationic or potentially cationic functional groups. For example, the cationic polymer may contain free amino groups, which, after introduction into the pulp slurry with a relatively low pH value for the protonation of the free amino groups become cationic. However, in the preferred embodiment, the cationic polymers have a permanent cationic charge, in particular a Quaternary ammonium group.

Additional flocculant/coagulant may be used in addition to the above pre-processing stage of cationactive the m material. In a particularly preferred system additional flocculant/coagulant is also a means of pre-treatment cationic material. Thus, for pre-treatment of pulp suspensions of cationic material of this preferred method comprises adding a cationic flocculant/coagulant in the pulp suspension or in one or more components of the pulp suspension. In further perform other stage flocculation of the suspension, including adding a water-soluble branched anionic polymer and the silicon-containing material.

As a cationic flocculant/coagulant is necessary to use water-soluble polymer, which may be, for example, a relatively low molecular weight polymer with a relatively high cationactive. For example, this polymer can serve as a homopolymer of any suitable ethylene-unsaturated cationic monomer that is polymerized to obtain a polymer with a characteristic viscosity of up to 3 DL/g Preferred homopolymers of diallyldimethylammoniumchloride. Low molecular weight polymer with high cationactive may be a polymer obtained stepwise polymerization, formed by the polycondensation of amines with other acceptable di - elitetanning materials. For example, this polymer can be obtained by reaction of one or more amines selected from dimethylamine, trimethylamine, Ethylenediamine, etc. with epichlohydrin, and preferred epichlorohydrin.

Preferred cationic flocculant/coagulant is a polymer, which is obtained from the water-soluble ethylene-unsaturated cationic monomer or mixture of monomers, where at least one of the monomers in the mixture is cationic or potentially cationic. Under the water-solubility is meant that the solubility of the monomer in water is at least 5 g/100 tubes Preferred cationic monomer is selected from diallyldimethylammoniumchloride, acid additive salts and Quaternary ammonium salts or dialkylaminoalkyl(meth)acrylate, or dialkylaminoalkyl(meth)acrylamides. The cationic monomer may be polymerized alone or copolymerization with water-soluble nonionic, cationic or anionic monomers. The most preferred such polymers have characteristic viscosity of at least 3 DL/g, for example reaching 16 or 18 DL/g, but is usually in the range from 7 or 8 to 14 or 15 DL/g

Especially preferred cationic polymers include copolymers methylchloride the Quaternary ammonium salts of dimethylaminoethylacrylate or-methacrylate. As water-soluble cationic polymer may be used a polymer with a rheological oscillation value of tan Delta at 0.005 Hz more than 1.1 (determined in the present description of the method), such as proposed in co-pending application for patent with priority based on patent application US room 60/164231 (the reference number PP/W-21916/P1/AC 526), filed with the same priority date as this application.

Water-soluble cationic polymer may also have a slightly branched structure, which is achieved, for example, the introduction of small quantities of agent education branches, in particular up to 20 miscast./million To typical agents of education branches are any agents of education branches, which in the present description is presented as acceptable for obtaining a branched anionic polymer. Such branched polymers can also be obtained by the inclusion in the monomer mixture control degree of polymerization. Control degree of polymerization can be included in the amount of at least 2 miscast./million and can be used up to 200 miscast./million As a rule, the content of the control degree of polymerization is in the range from 10 to 50 miscast./million as a regulator of the degree of polymerization can be used any acceptable chemical substance, for example hypophosphite sodium, 2-mercaptoethanol, malic acid or thioglycolate acid.

Branched polymers can be obtained by using a controller of the degree of polymerization and using more substantial quantities of agent education branches, for example up to 100 or 200 miscast./million, assuming the number of control degrees of polymerization are sufficient to guarantee that the resulting polymer has solubility. Branched cationic water-soluble polymer, as a rule, can be obtained from the water-soluble monomer mixture comprising at least one cationic monomer, at least 10 molar ppm million regulator polymerization degree and less than 20 molar ppm million agent education branches. Preferred branched water-soluble cationic polymer has a rheological oscillation value of tan Delta at 0.005 Hz 0,7 more (determined in the present description of the method). The characteristic viscosity of the branched cationic polymers, typically, is at least 3 DL/g Such polymers generally possess a characteristic viscosity in the range from 4 or 5 to 18 or 19 DL/g Characteristic viscosity of the preferred polymers is the t 7 or 8 to about 12 or 13 DL/g Cationic water-soluble polymers can also be obtained by any convenient method, for example by polymerization in solution, the polymerization in suspension of water in the oil or by polymerization in emulsion of water in oil. In the polymerization in solution form aqueous polymer gels that can be cut, dried and grind with cooking powdered product. The polymers can be obtained in the form of a bead suspension polymerization or emulsion or dispersion of water in oil by polymerization in emulsion of water in oil, for example in accordance with the method described in EP-A 150933, EP-A 102760 or EP-A 126528.

When florulenta system includes a cationic polymer, it is usually added in a quantity sufficient to effect flocculation. Usually the concentration of the cationic polymer is, apparently, more than 20 miscast./million, calculated on the dry weight of the suspension. In a preferred embodiment, the cationic polymer is added in the amount of at least 50 miscast./million, for example from 100 to 2000 miscast./million Concentration of this polymer, as a rule, can be from 150 to 600 miscast./million, mainly in the range from 200 to 400 ppm million

Typical content of the anionic branched polymer may be at least 20 miscast./million, calculated on the dry weight is the second suspension, although in the preferred embodiment, it is at least 50 miscast./million, in particular in the range from 100 to 2000 miscast./million Number in the range from 150 to 600 miscast./million preferred, predominantly within the range from 200 to 400 miscast./million Silicon-containing material can be added in amounts of at least 100 miscast./million, calculated on the dry weight of the suspension. The required concentration of silicon-containing material is in the range from 500 or 750 to 10,000 miscast./million Was determined that the most effective concentration of silicon-containing material ranges from 1000 to 2000 miscast./million

In one preferred embodiment, after adding at least one of the components floculants system pulp suspension is subjected to mechanical treatment of the shear force. Thus, in this preferred embodiment, at least one component floculants system mix in the pulp suspension, causing flocculation, and then flocculated suspension is subjected to mechanical treatment of the shear force. This stage is the impact of shear stress that can be carried out by passing the flocculated slurry through one or more means of shear processing selected from the means for pumping, cleaning or mixing. So, for example, the e means of shear processing include centrifugal pumps and centrifugal sorting, but they could be any other tools used in the process, in which the influence of the shear force.

Requires machining of the shear force acting on flocculated suspension in such a way as to destroy the flakes. At the stage of exposure to shear stress, you can add all the components floculants system, although in the preferred embodiment, at least the last component floculants system is introduced into the pulp slurry at the point of the technological process, after which the drainage from the casting sheet significant impact shear force was absent. Therefore, in a preferred embodiment, the pulp suspension add at least one component floculants system, and then flocculated suspension is subjected to mechanical processing shear force, during which the flakes are mechanically destroy, then add at least one component floculants system for re-flocculation of the suspension before drainage.

In accordance with a more preferred implementation of the invention in the pulp suspension introduced a water-soluble cationic polymer, and then the suspension is subjected to mechanical treatment of the shear force. Later in suspension, add the silicon-containing material and water-soluble branched anionic polymer. Anionic branched polymer and the silicon-containing material can be added either in the form of a pre-mixed composition, or separately, but at the same time, but it is preferable to add them sequentially. Thus, the suspension can be re-flocculating the addition of branched anionic polymer, and then the silicon-containing material, but in the preferred embodiment, the suspension is again localroot the addition of silicon-containing material, and then branched anionic polymer.

In the pulp suspension can be added to the first component floculants system, then flocculated slurry can pass through one or more means of shear force. Further, we can introduce the second component floculants system for re-flocculation of the suspension, and then re-flocculated suspension can be subjected to additional machining of the shear force. Processed shear force re-flocculated slurry can also be subjected to additional flocculation by adding a third component floculants system. When the steps for adding components floculants system separated by stages of exposure to shear stress, in a preferred embodiment, the branched anionic poly the EP added as the last component.

In another variant implementation of the invention the pulp slurry can not be subjected to any significant effect of shear force after addition of the suspension of any of the components floculants system. Silicon-containing material, anionic branched polymer and, when you include it, water-soluble cationic polymer can fully enter into the pulp suspension after the last processing tools shear force before drainage. In this embodiment, a water-soluble branched polymer can be the first component, followed by the cationic polymer (if you include it), and then the silicon-containing material. However, you can also resort to other orders of their introduction.

According to one preferred variant implementation of the present invention proposes a method of making paper from slurry pulp of fibrous mass comprising a filler. The filler may be any of conventionally used filling materials. For example, the filler may be a clay, such as kaolin, or the filler may be calcium carbonate, which could be applied powdered calcium carbonate or, in particular, precipitated calcium carbonate, or may be preferred when is the change of titanium dioxide as a filling material. Examples of other filling materials include synthetic polymeric fillers. Usually cellulosic fibrous mass comprising substantial amounts of filler, harder flocculating. This is especially true in cases fillers of particles of very small size, such as precipitated calcium carbonate.

Thus, in accordance with the preferred object of the present invention proposes a method of manufacturing paper filled with. Fibrous material for the manufacture of paper may include any suitable amount of filler. Usually the pulp suspension comprises at least 5 wt.% filling material. Typically, the amount of filler is up to 40%, preferably ranges from 10 to 40%. When using the filler, it may be contained in the finished sheet of paper or paperboard in an amount up to 40%. Therefore, in accordance with this preferred object of the present invention proposes a method of manufacturing paper or cardboard, which first proposed the use of pulp suspensions, comprising a filler, and in this suspension of solid particles localroot introduction to suspension floculants system that includes a silicon-containing material and water-soluble branched anionic polymer, as he predstavlen the present description.

In another variant implementation of the invention features a method of making paper or paperboard of a suspension of cellulosic fibrous pulp, which contains almost no filler.

The invention is illustrated by the following examples.

Example 1 (comparative)

Drainage properties determined using the modified instrument Shopper-Rigler (Schopper-Riegler) with the locked rear hole, resulting in drainage water exits through the front hole. Used cellulosic fibrous mass is a suspension of bleached birch/bleached pine fibrous mass 50/50 containing 40 wt.% (in terms of total weight of dry matter) of precipitated calcium carbonate. Before adding the filler suspension of the fibrous mass is crushed to the consistency of grind 55° (determined by the method of Shopper-Rigler). This suspension is injected 5 kg/t (based on the total weight of dry matter) of cationic starch [the degree of substitution (Sz): 0,045].

This fibrous mass is mixed copolymer of acrylamide and methylchloride Quaternary ammonium salts dimethylaminoethylacrylate (mass ratio of 75/25) with a characteristic viscosity greater of 11.0 DL/g (product A), and then after exposure to shear stress using a mechanical stirrer in the fibrous mass, padmesh who live branched water-soluble anionic copolymer of acrylamide and sodium acrylate (mass ratio of 65/35) with 6 miscast./million methylenebisacrylamide the characteristic viscosity of 9.5 DL/g and oscillatory rheological the value of tan Delta at 0.005 Hz of 0.9 (product B). When various concentrations of product a and product B measure the drainage time in seconds to obtain 600 ml of filtrate drainage. The drainage time in seconds are given in table 1.

Table 1
Product a (g/t)Product B (g/t)
  02505007501000
 010831181515
 250982712911
 500962610129
 75010318988
 100010918988
 200012520976

Example 2

Drainage tests of example 1 is repeated using the product And in the end is Tracii 500 g/t and product B at a concentration of 250 g/t, except that after exposure to shear stress, but just before the introduction of product B add aqueous colloidal silica. The time of drainage are shown in table 2.

Table 2
The concentration of colloidal silica (g/t)The drainage time (s)
026
12511
2509
5007
7507
10006

It is obvious that even at a concentration of 125 g/t colloidal silica significantly improves drainage.

Example 3 (comparative)

Standard sheets of paper manufactured using a slurry of cellulosic fibrous pulp of example 1 and infused into the fibrous mass of the first product And the indicated concentrations, and then action on the suspension shear force 60 seconds at a speed of rotation of the agitator 1500 rpm and the subsequent adulteration of product B at a specified concentration. Further flocculated fiber was poured on a grid of small cells with casting sheet, which is then dried on a drum dryer at 80°C for 2 hours Casting sheets of paper control device Scnner Measurement System, created the firm PIRA International. For each image calculated standard deviations (SD) from the mean (the standard deviation of grey values). Indicators molding for each concentration of product a and product B are given in table 3. Smaller values indicate superior results.

Example 4

Example 3 is repeated, except that the product And used at a concentration of 500 g/t, product B at a concentration of 250 g/t and after exposure to shear stress, but directly before adding the product B is injected 125, 250, 500, 750 and 1000 g/t of aqueous colloidal silica. The corresponding figures forming for each concentration of aqueous colloidal silica are shown in table 4.

Table 4
The concentration of colloidal silica (g/t)Indicator molding
010,88
12514,26
25017,25
50019,31
75018,47
100018,05

Comparison of concentrations required to achieve equivalent results drainage, shows that the use of floculants system, including cationactive polymer, colloidal silica and branched anionic water-soluble polymer that provides improved molding. For example, according to example 2 at concentrations of polymer And 500 g/t polymer B 250 g/t and silicon dioxide 1000 ppm time drainage is 6 C. From table 4 it is evident that at equivalent concentrations of the product And, of silicon dioxide and product B figure molding is 18,05. According to example 1 at concentrations of product And 2000 g/t of product B 1000 g/t in the absence of silicon dioxide is provided by the time of drainage 6 C. According to table 3, when equivalent concentrations of product a and product B provides a measure of the molding 29,85. Thus, at equivalent high values of drainage implementation of the invention allows to improve the rate of formation of more than 39%. Improved molding can still be observed even at equivalent higher values of drainage, for example 11 C.

Therefore, data from these examples we can see that the use of floculants system comprising a cationic polymer, colloidal silica and branched anionic water-soluble polymer, provides fast drainage and improved molding in comparison with achievable when using a cationic polymer and a branched anionactive the water-soluble polymer in the absence of colloidal silicon dioxide.

In the drawing, curve a is a graph of the performance of the drainage-molding two-component systems of examples 1 and 3 using 1000 g/t branched anionic polymer (product B) and 250, 500, 750, 1000 and 2000 g/t of cationic polymer (product A). Curve is a graph of the performance of the drainage-molding for three-component systems of examples 2 and 4 using 250 g/t branched anionic polymer (product B), 500 g/t of cationic polymer (product a) and (125, 250, 500, 750 and 1000 g/t of colloidal silica. The aim is approaching zero indicator as molding and drainage. It is obvious that the implementation of the method according to the invention achieves the overall best drainage and formation.

Example 5 (comparative)

Retention properties determined by standard methods of Dynamic Britt Jar suspension of pulp of example 1 when used floculant system comprising a cationic polymer (product a) and the branched anionic polymer (product B) in the absence of colloidal silica. This floculant system added in the same manner as in example 3. General data retention percentages are presented in table 5.

Table 5
 Product B (g/g)
 02505007501000
Product a (g/t)063,5084,1790,4894,44of 96.35
 12533,5873,4487,6692,2794,59
 25034,7281,2092,1297,1598,10
 50037,4384,7794,8697,6598,58
 100036,0184,6894,9197,1699,19
 200045,2496,92a 99.1699,6399,76

Example 6

Example 5 is repeated, except that as floculants systems use 250 g/t of cationic polymer (product A), 250 g/t branched anionic polymer (product B) and from 125 to 1000 g/t of colloidal silica. This floculant system added in the same manner as in example 4. Summary data retention are presented in table 6.

Table 6The concentration of colloidal silica (g/t)The rate of retention (%)081,2012588,6925091,3450094,1375095.92100095,20

According to the data presented in table 5, when the concentration of cationic polymer (product A) 250 g/t and branched anionic polymer (product B) 250 g/t indicator retention is 81,20. The introduction of 500 ppm colloidal silica indicator retention increase to 94,13. To achieve equivalent retention in the absence of colloidal silica concentration of 500 g/t of product a and 500 g/t of product B.

1. Method of making paper or paperboard comprising preparing a pulp suspension, flocculation of the suspension with a water-soluble cationic polymer with stirring until the formation of flakes, adding a silicon-containing material and anionic water-soluble polymer, draining the suspension on the grid casting sheet and the subsequent drying of the sheet, characterized in that the anionic water-soluble polymer is an anionic branched in rastvorimy polymer, which is produced using a water-soluble ethylene-unsaturated anionic monomer or monomer mixture and agent education branches, where the anionic polymer has

(a) the characteristic viscosity at least 4 DL/g;

(b) rheological oscillation value of tan Delta at 0.005 Hz 0,7 more calculated 1.5 wt.% an aqueous solution of the polymer, and/or

(a) shows the viscosity of the TLU in deionized water, which is at least three times shows the viscosity of the TLU in the salt solution of the corresponding non-branched anionic polymer obtained in the absence of the agent, the formation of branches in which the water-soluble cationic polymer is added to the pulp slurry and then the slurry is mechanically treated, then add silicon-containing material and the anionic branched water-soluble polymer.

2. The method according to claim 1, wherein a material comprising silicon-containing material is chosen from the group comprising particles on kremmidiotis basis, kremmidiotis the microgels, colloidal silica, colloidal solution of silicic acid, silica gels, polysilicates, cationic silica, aluminosilicates, polyaluminosilicate, borosilicate, polymorbidity and zeolites.

3. SPO is about according to claim 1 or 2, in which the silicon-containing material is an anionic material of the microparticles.

4. The method according to any one of claims 1 to 3, in which the silicon-containing material and the anionic polymer is introduced into the pulp slurry in sequence.

5. The method according to any one of claims 1 to 4, in which the suspension is injected silicon-containing material, and then the suspension is injected anionic branched polymer.

6. The method according to any one of claims 1 to 5, in which the suspension is imposed anionic branched polymer, and then the suspension type silicon material.

7. The method according to any one of claims 1 to 6, in which the cationic polymer chosen from water-soluble cationic organic polymers or inorganic materials, such as polyaluminium.

8. The method according to any one of claims 1 to 7, in which the cationic polymer is produced using a water-soluble ethylene-unsaturated monomer or a water-soluble mixture of the ethylene-unsaturated monomers comprising at least one cationic monomer.

9. The method according to any one of claims 1 to 8, in which the cationic polymer is a branched cationic polymer, which has a characteristic viscosity above 3 DL/g and exhibits a rheological oscillation value of tan Delta at 0.005 Hz 0,7 more, calculated at 1.5 m is S.% aqueous solution of the polymer.

10. The method according to any one of claims 1 to 9, in which the cationic polymer has a characteristic viscosity above 3 DL/g and exhibits a rheological oscillation value of tan Delta at 0.005 Hz more than 1.1 calculated 1.5 wt.% an aqueous solution of the polymer.

11. The method according to any one of claims 1 to 10, in which the pulp suspension includes a filler.

12. The method according to claim 11, in which a sheet of paper or paperboard includes a filler in an amount up to 40 wt.%.

13. The method according to claim 11 or 12, in which the filler material selected from precipitated calcium carbonate, ground calcium carbonate, clay, preferably kaolin, and titanium dioxide.

14. The method according to any one of claims 1 to 10, in which the pulp suspension contains almost no filler.



 

Same patents:

FIELD: paper-and-pulp industry.

SUBSTANCE: process comprises preparation of paper pulp, flocculation of pulp, drainage of pulp on the screen to form sheet, and subsequent drying of sheet. Flocculation involves flocculation system including clay and water-soluble anionic branched polymer. The latter is prepared using water-soluble anionic ethylenically-unsaturated monomer or monomer mixture and ramification-forming agent. Polymer is characterized by intrinsic viscosity above 1.5 dl/g and/or Brookfield viscosity in salt solution above about 2.0 mPa·s, rheological oscillation delta tangent value at 0.005 Hz above 0.7, and/or reduced viscosity in deionized water at least thrice exceeding reduced viscosity in salt solution of corresponding nonbranched polymer obtained in absence of ramification-forming agent.

EFFECT: improved drainage, retention, and formation process.

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FIELD: paper industry.

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41 cl, 6 tbl, 6 ex

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20 cl, 10 tbl, 8 ex

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EFFECT: improved drainage, retention, and formation process.

14 cl, 1 dwg, 6 tbl, 6 ex

FIELD: paper-and-pulp industry.

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11 cl, 4 dwg, 5 tbl, 3 ex

FIELD: textiles, paper.

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EFFECT: increase in degree of retention of filler.

2 cl, 5 ex, 1 tbl

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