Bleached mechanical pulp and method for producing the same

FIELD: bleached mechanical pulp based on fibrillated cellulose fibers, hemicelluloses and lignin, paper made from said pulp, and method for producing said pulp using crystallized calcium carbonate in pulp-and-paper industry.

SUBSTANCE: method involves crystallizing calcium carbonate in said pulps and at least partly covering fibrillated cellulose fibers, hemicelluloses and lignin, with which calcium carbonate is strongly bound by mechanical binding. Method involves forming homogeneous water suspension by mixing lime and leached mechanical pulp based on fibrillated cellulose fibers, hemicelluloses and lignin; adding carbon dioxide into resulting suspension while mixing and keeping its temperature within the range of 10-50 C until lime is converted into calcium carbonate.

EFFECT: simplified method and improved quality of bleached mechanical pulp.

12 cl, 21 dwg, 5 tbl

 

The technical FIELD

The present invention relates to the production technology of paper and more particularly to paper and paper pulp. In particular, an object of the present invention are new bleached mechanical pulp, the method of its production and the paper received from the paper pulp.

PRIOR art

Paper pulp made from wood and used in the manufacture of paper, can be either mechanical paper pulp, chemical paper pulp.

Mechanical paper pulp obtained directly from debarked logs, saw mill residues or of shavings, contains all the components present in the original wood, in particular cellulose, hemicellulose and lignin.

Mechanical paper pulp means pulp produced from wood using a mechanical process of grinding and/or milling, this process may be accompanied by chemical, physical or thermal treatments, either separately or simultaneously, and one of the characteristics of this paper pulp is that it contains most of the lignin initially contained in the wood.

Before chopping often perform a preliminary chemical treatment. For example, wood chips can be soaked in hydrogen peroxide (feast upon the authorized oxygen water), containing caustic soda production process, the APMP). "Alkaline Peroxide Mechanical Pulp" - "Alkaline peroxide mechanical pulp) or sodium sulfite (production process STMR from the English. "Chemo Thermo Mechanical Pulp" - "chemi-thermomechanical pulp"). This type of chemical treatment violates the compact structure of the fibers and reduces energy consumption during the grinding stage.

As a result of crushing and grinding, used in the production of mechanical pulp, the level of humidity shopper Reglero (SCHOPPER RIEGLER, SR) this paper pulp is usually more 22°.

In addition, used the milling process leads to a large variation in sizes of the fibers because of the tears and delaminations that occur in the walls of the fibers, and the phenomenon of circumcision fibers. Fragments of fibres, fibrils and fibrillated fibers define properties STMR (from the English. "Bleached Chemi Thermo Mechanical Pulp" - "bleached chemi-thermomechanical pulp"), has a significantly higher specific surface area compared to chemical paper pulp (.Cannel and R.Cockram, PPI, May 2000, p.51-61).

Chemical pulp is produced using processes that contribute to the separation of cellulose fibers with minimal degradation. The principle consists in the removal of much of the lignin and part of the hemicellulose associated with leagues is different, by means of dilute paper pulp aqueous medium containing the appropriate reagents, for example:

process with acid sulfite: N2SO3(SO2)/NaHSO3,

process with neutral sulfite: Na2SO3(NaHSO3)/NaHCO3(Na2CO3),

process with the sulfate (Kraft): NaOH, Na2S(NaHS)/Na2CO3,

process with soda: NaOH/Na2CO3.

In particular, in the manufacture of white paper, it is often necessary to bleach chemical or mechanical pulp. This bleaching is done with the use of chemical products, which consists of either the dissolution and extraction of a portion of the lignin, or discoloration. These chemicals include chlorine dioxide, hydrogen peroxide and ozone in the case of chemical paper of the masses and the hydrogen peroxide in the case of mechanical paper mass. The residual lignin content in bleached mechanical paper mass is much higher than its content in bleached chemical paper the masses, as most of the lignin remains in the fibers (.Cannel and R.Cockram, PPI, May 2000, p.51-61).

These paper pulp used for paper production, which can be subjected to special treatment during production in order to give it special characteristics. For example, the addition of mineral fillers, such as kaolin, aluminum oxide t is Tana, talc, calcium carbonate improves the suitability of the paper for printing, opacity and dimensional stability of paper.

Mechanical paper pulp have the following special advantages over chemical paper mass (.Cannel and R.Cockram, PPI, May 2000, 51-61):

- lower investment costs,

- efficient use of wood (85-95%, compared with 42-52% for the chemical paper of the masses), and as a consequence get them for less

- improve some physical properties of the paper obtained from these paper masses, such as thickness, opacity and stiffness,

- less impact on the environment, provided the wastes.

However, one of the main obstacles for the use of mechanical paper masses is their tendency to yellowing under the action of light. Usually it is considered that the photochemical reactivity mainly due to the high content of lignin in mechanical paper mass. Lignin has a tendency to oxidation with the formation of colored products. STMR-mass ("Bleached Chemi Thermo Mechanical Pulp" - "bleached chemi-thermomechanical pulp"), for example, used primarily for paper production with low value added through processing, and short shelf life due to the fact that it turns yellow under the action of light (Nordic Pulp and Paper Research Journal,1998, 13(3), 198-205).

Thus, promising industrial applications mechanical paper mass to a large extent depend on the development of new cost-effective technologies for improving light fastness of these mechanical paper mass and due to this restriction, their yellowing. For example, on the surface of the paper can be coated with a protective agent, such as absorbers of UV radiation and antioxidants to limit the yellowing of paper produced from mechanical paper mass. These supplements, the most effective of which are derivatives of benzophenone, benzotriazole and diaminostilbene, slow down the yellowing under the action of light, but not completely solve the problem (.Li and A.J.Ragauskas, Journal of Pulp and Paper Science, Vol.27, No. 6, June 2001, p.202; S.Bourgoing, E.Leclerc, P.Martin and S.Robert, Journal of Pulp and Paper Science, Vol.27, No. 7, July 2001, p.240).

In addition, these additives are expensive and have a negative impact on the opacity and color of the paper. Moreover, these additives are destroyed over time, which leads to a gradual reduction in their effectiveness over time.

Another approach, which was proposed to solve the yellowing of mechanical paper pulp under the action of light, was deposited on each side of a sheet of paper, at least 5 g/m2pigmented compositions containing at least 10% of titanium dioxide with p is the established levels of rutile (R.W.Johnson, Tappi Journal, May 1991, 209). This proposed solution is not widely used in industry because of the limitations associated with the high price of titanium dioxide, the limited use of paper-making machines with the appropriate devices for coating, and due to the fact that this decision is limited to the production of coated paper and therefore cannot be used in the manufacture of uncoated paper.

The INVENTION

There is therefore a need to develop new ways of bleached mechanical paper masses with high light fastness.

Another objective of the present invention is to obtain a simple, economical and suitable for use in industry paper pulp limited yellowing under the action of light.

In this context, the object of the present invention is bleached mechanical pulp based fibrillated fibers of cellulose, hemicellulose and lignin, containing calcium carbonate, and characterized in that the calcium carbonate crystallizes and at least partially covers the fibrillated fibers consisting of cellulose, hemicellulose and lignin, with which the calcium carbonate is connected mechanically.

It was demonstrated that, when fibrillated fibers, consisting of the cellulite, tighten the SHL, hemicellulose and lignin, are at least partially covered with crystallized calcium carbonate, the stability of the resulting paper pulp increases. One explanation is that this coating protects the lignin from the light due to the grains of calcium carbonate, which limits its oxidation that causes yellowing of the paper pulp and the paper.

Another object of the invention is to provide a new method of increasing the stability of bleached mechanical paper mass to the action of light.

The next task of the present invention is a method for the production of paper pulp according to the present invention, comprising the following steps:

(a) formation of a homogeneous aqueous suspension by mixing pre-bleached mechanical pulp based fibrillated fibers consisting of cellulose, hemicellulose and lignin in an aqueous environment with a number of shopper-Rigler equal to at least 22°and lime,

(b) if the solids content in the suspension obtained in stage (a), more than 10 mass %, the specified dilution of the suspension is carried out until, until the resulting suspension containing the fraction of dry matter less than 10 mass % and preferably less than 5 mass %,

(b) adding carbon dioxide by injection into the above suspension in which the process of mixing the specified suspension and maintain its temperature in the range between 10 and 50° With up to full conversion of the lime into calcium carbonate, which crystallizes in situ.

Other features of the invention will be clear after reading the description below with reference to the accompanying graphic materials.

A BRIEF DESCRIPTION of GRAPHIC MATERIALS

Figure 1-7 are images of different paper masses, obtained with a scanning electron microscope (SEM):

figure 1 is an image with the increase of 204 times, demonstrating pulp obtained using STMR RANGER SLAVE LAKE PULP CORPORATION R250B85 at 52°SR,

figure 2 is an image with the increase in 4180 times, demonstrating the pulp according to the present invention obtained with 30% BCTMP RANGER SLAVE LAKE PULP CORPORATION R250B85 at 38°SR and 70% of caso3obtained from unground slaked lime,

figure 3 is an image with the increase in 4110 times, demonstrating the pulp according to the present invention obtained with 30% BCTMP RANGER SLAVE LAKE PULP CORPORATION R250B85 at 38°SR and 70% of caso3obtained from powdered slaked lime,

figure 4 is an image with the increase in 4060 times, demonstrating the pulp according to the present invention obtained with 30% BCTMP RANGER SLAVE LAKE PULP CORPORATION R250B85 at 52°SR and 70% of caso3obtained from unground slaked lime,

figure 5 - this image is agenie with the increase in 4100 times showing pulp according to the present invention obtained with 30% BCTMP RANGER SLAVE LAKE PULP CORPORATION R250B85 at 52°SR and 70% of caso3obtained from powdered slaked lime,

6 is an image with the increase in 4050 times, demonstrating the pulp according to the present invention, obtained using 50% BCTMP RANGER SLAVE LAKE PULP CORPORATION R250B85 at 38°SR and 50% caso3obtained from powdered slaked lime,

7 is an image with the increase in 4050 times, demonstrating the pulp according to the present invention, obtained using 70% BCTMP RANGER SLAVE LAKE PULP CORPORATION R250B85 at 38°SR and 30% caso3obtained from the crushed lime.

Fig-10 show variations of the degree of whiteness (index CIE) different types of paper mass according to the present invention as a function of exposure time, obtained using accelerated testing:

Fig demonstrates limited yellowing paper mass according to the present invention,

Fig.9 shows the effect of grinding used lime,

figure 10 shows the influence of the content of calcium carbonate.

11-21 show SEM images of paper mass according to the present invention, obtained from different types and varieties of mechanical paper mass:

11 is from the expression with increase in 4050 times showing pulp according to the present invention obtained with 30% mechanical pulp TEMCELL BIRCH BULK at 24°SR and 70% of caso3obtained from powdered slaked lime,

Fig is an image with the increase in 4100 times, demonstrating the pulp according to the present invention obtained with 30% mechanical pulp TEMCELL 325/85 at 38°SR and 70% of caso3obtained from powdered slaked lime,

Fig is an image with the increase in 4140 times, demonstrating the pulp according to the present invention obtained with 30% mechanical pulp TEMCELL 250/85 HW at 43°SR and 70% of caso3obtained from powdered slaked lime,

Fig is an image with the increase in 4100 times, demonstrating the pulp according to the present invention obtained with 30% mechanical pulp MILLAR WESTERN 325-85-100 at 38°SR and 70% of caso3obtained from powdered slaked lime,

Fig is an image with the increase in 4100 times, demonstrating the pulp according to the present invention obtained with 30% mechanical pulp ROTTNEROS SA 783 at 32°SR and 70% of caso3obtained from powdered slaked lime,

Fig is an image with the increase in 4100 times, the demo is strenuous pulp according to the present invention, obtained using 30% mechanical pulp SODRA 100 / 80g at 70°SR and 70% of caso3obtained from powdered slaked lime,

Fig is an image with the increase in 4140 times, demonstrating the pulp according to the present invention obtained with 30% mechanical pulp WAGGERYD CELL AB. With 50/78 when 62°SR and 70% of caso3obtained from powdered slaked lime,

Fig is an image with the increase in 4140 times, demonstrating the pulp according to the present invention obtained with 30% mechanical pulp SCA (Ostrand) HT TISSUE 001 at 24°SR and 70% of caso3obtained from powdered slaked lime,

Fig is an image with the increase in 4100 times, demonstrating the pulp according to the present invention obtained with 30% mechanical pulp ZUBIALDE RHZ at 58°SR and 70% of caso3obtained from powdered slaked lime,

Fig is an image with the increase in 4010 times, demonstrating the pulp according to the present invention obtained with 30% mechanical pulp M-REAL SPHINX 500/80 at 25°SR and 70% of caso3obtained from powdered slaked lime,

Fig is an image with the increase in 4100 times, demonstrating the pulp according to the present invention obtained with 30% mechanical pulp RONDCHATEL 8255 at 52° SR and 70% of caso3obtained from the crushed lime.

INFORMATION CONFIRMING the POSSIBILITY of carrying out the INVENTION

Original paper the masses used in the method according to the present invention, are mechanical paper pulp, obtained from various species of wood, for example from softwood, hardwood or eucalyptus. Mechanical treatment may be accompanied by chemical treatment; for example, as the initial product can be used paper pulp STMR type.

In the mechanical process by which they were received, all used mechanical paper pulp had the level of SR over 22°. Cellulose fibers contained in these hard masses, also had a certain level of fibrillatory.

In the present invention used standard method of measurement values SR, described in ISO 5267-1, this method can be used to determine the drainage characteristics of the aqueous suspension of paper pulp as a function of its value SR.

These paper pulp pre-bleached according to standard methods, well known to experts in the art, for example using oxygenated water (hydrogen peroxide), and then spent stage (a), (b) and (C) of the method according to astasia invention.

Stage (a) is to form a homogeneous aqueous slurry by placing pre-bleached source of mechanical paper pulp in the presence of lime in the aquatic environment.

Thus, lime, or calcium hydroxide, is a source of calcium ions CA2+. You can use lime or lime already in the form of a suspension in water (hydrated). Pulp and lime can be entered into the appropriate reactor type Chan directly in the form of suspension. For example, you can add the pulp in the form of a water suspension containing from 0.1 to 10 mass % of dry matter, and then under moderate stirring add aqueous suspension of lime, containing from 0.1 to 30%, preferably 13 mass %, dry matter. Moderate stirring means, for example, the mixing speed of the mixer is of the order of from 1 to about 30/min

According to a preferred form of implementation of the present invention, which further enhanced resistance to yellowing under the action of light, and therefore the whiteness of bleached mechanical pulp according to the present invention, used lime is in the form of particles with an average diameter of less than 9 μm and preferably 5 μm. This particle size can be obtained, for example, when using hydrated lime, preliminary evaluation of the bent-wet grinding in microsurvey mill, for example, in the mill, manufactured by WAB AG Company (Basel) called DYNO®-Mill KD type. The average particle diameter of lime is measured using a laser granulometer type 230, manufactured by COULTER Company.

After that, the suspension should have a dry matter content of less than 10 mass %, and preferably equal to 2.5%, in order calcium carbonate crystallized in good conditions. The dry matter content determines the viscosity of the suspension. The viscosity should not be too high, in order to guarantee the homogeneity of the reaction mixture. Therefore, stage dilution (b) is to regulate the composition of the suspension prepared in stage (a), if the dry matter content is too high, so that it had the required dry matter content (namely, less than 10%), corresponding to the required viscosity.

Preferably, the suspension is formed from paper pulp and lime, not stored for more than 30 minutes to prevent reaction of the lignin present in and on the fibers, with lime, which will lead to yellowing paper pulp. Therefore, stage (a) and (b) of the method preferably should last less than 30 minutes.

The subsequent stage (b) comprises adding gaseous carbon dioxide by injection into this diluted suspension at a stable temperature range is between 10 and 50° With stirring, the suspension and the temperature of the suspension in the range between 10 and 50°up until the lime will not be completely converted to calcium carbonate crystallized in situ.

Thus, carbon dioxide (CO2) is the source of carbonate ions CO32-. Carbon dioxide Inuktitut in suspension, for example, with a bulk velocity of from 0.1 to 30 m3/h/kg calcium hydroxide, preferably 15 m3/h/kg After adding carbon dioxide, the reaction mixture was vigorously stirred, for example, a rotation speed of between 100 and 3000 rpm, preferably at 500 rpm

The reaction stops when all initially present lime reacts, which reduces the pH of the suspension, which was originally alkaline and therefore had a pH of about 12 to a neutral pH, which at the end of the reaction is stabilized at level 7.

As already indicated, the crystallization of calcium carbonate on the fibers of cellulose, hemicellulose and lignin may occur in the reactor type Chan using intermittent (periodic) process. You can also use a continuous process, in which various reagents sequentially Inuktitut and stirred tubular reactor type, equipped with static mixers. This SL is tea original pulp send in a tubular reactor, then Inuktitut aqueous suspension of lime, after which Inuktitut CO2at several points. Before each point of injection of the tubular reactor contains an appropriate number of static mixers of the appropriate type, which make the mixture homogeneous, so that the reaction can occur uniformly, and calcium carbonate may crystallize, is uniformly distributed on the fibers of cellulose, hemicellulose and lignin.

The tubular reactor should be sufficiently long to allow the reaction was completed at the exit of the reactor. This length depends on the used concentrations of the products and bulk velocity.

From the industrial point of view, this type of continuous process has several advantages: no need for intermediate storage tank; you can adjust the volumetric flow rate in order to adapt it to the consumption output; injection of lime and CO2you can instantly stop, if you have problems at the reactor outlet, and so there is no need to store intermediate product.

You can also use a hybrid continuous-periodic process. In this case, the original pulp and lime added sequentially in the VAT while stirring. The resulting slurry is then sent to a tubular reactor, in which Inuktitut CO2in one or more points. Trobc the th reactor equipped with a sufficient number of static mixer to ensure homogeneity of the reaction mixture. And in this case the tubular reactor should be sufficiently long to ensure that the reaction was completed to the exit of the reactor.

In the patent FR 9204474 described method for the production of new complex products intended primarily for building materials, paper products, non-woven opaque substrate and which includes stages similar to the stages (a), (b) and (C) in the method according to the present invention. The technical problem that you are trying to solve it using the method described in FR 9204474, is to get the product with high resistance and/or adhesion under the application of a mechanical stress. Suddenly, the author demonstrated that the application of the method of this type to pre-bleached mechanical paper mass consisting of cellulose, hemicellulose and lignin, can improve the stability of the obtained paper to the action of light due to the reduction of yellowing.

According to the method described in the present invention, the calcium carbonate crystallizes mainly in the form of clusters of grains, covering fibers of cellulose, hemicellulose and lignin, with the formation of relabeling mechanical linkage with a good distribution and the preferred concentration on areas with the highest specific surface area.

Therefore, paper pulp according to the present invention have determined the military structure: the calcium carbonate crystals are distributed and mechanically connected with fibrillated fibers, which due to this are coated, as shown in figure 2-7 and 11-21. These Figure 2-7 and 11-21 are photographs obtained by scanning electron microscopy (SEM) on the device type Stereoscan 90 Cambridge Instruments in hard masses according to the present invention, which have been previously dried using methods of critical points, described in the patent FR 9204474.

Figure 2-7 and 11-21 shows that in the selected examples of the carbonate crystallizes in the form of cubes. Working conditions can be modified to obtain crystals rhombohedral or scalenohedral form.

Paper pulp according to the present invention preferably contain more than 20 mass % and even more preferably more than 50 mass % calcium carbonate by weight of the total dry matter. For example, these paper pulp can contain from 20 to 75 mass % of calcium carbonate and from 80 to 25 mass % of cellulose, hemicellulose and lignin by weight of the total dry matter.

Other substances, for example podsinwowa substances may also be included in bleached mechanical pulp according to the present invention.

Another objective of the present invention is paper made from paper pulp according to the present invention. These varieties of paper is obtained using conventional methods output the VA paper, well-known specialists in this field of technology. Paper pulp according to the present invention are usually mixed with other masses for the manufacture of paper to obtain the maximum content of calcium carbonate is equal to, for example, about 10 to 40 mass % of the total dry matter content.

The following examples illustrate the invention without limiting it, and demonstrate that the grades obtained from mechanical paper mass, bleached according to the present invention is more resistant to yellowing under the action of light.

The first series of examples

These examples were carried out using filtered slaked lime or powdered slaked lime in the form of particles with an average diameter of 5 microns.

The dispersion of hydrated lime containing 25% dry matter (slaked lime extra white varieties LYS-Polienas production company BALTHAZARD and COTTE) and 1% Coatex GSN (production company SEATECH) as dispersant additives were diluted to obtain a dry matter content equal to 13%, and then filtered through a sieve with a mesh size of 100 microns. This lime is either used directly (not crushed lime), or crushed on microsurvey the DYNO®-Mill type KLD-Pilot to obtain particles with an average diameter of 5 microns.

Reactions were carried out in the ribbed reactor with a length of 52 m and a diameter of 10 mm, equipped with two static mixers, with the following parameters:

- The percentage of hydrated lime/STMR = in sufficient quantities to obtain ratios of caso3/STMR equal to 70/30, 50/50 or 30/70,

Percent dry matter content prior to injection CO22,5%,

- The reaction pressure of 4 bar

The pressure of CO26 bar

The reaction rate of 2 l/min,

The reaction temperature of 25°C

- The volumetric rate of CO26 l/min,

- the pH at the outlet of the reactor 6,4.

Paper weight STMR (code R250B85 (Poplar), the production company Ranger Slave Lake Pulp Corporation (Canada)) was used either in the form of solids at 38°SR, either in purified form at 52°SR.

There were prepared various paper weights, presented in Table 1.

Table 1
EXAMPLESTMRCaso3
°SR%Crushed%
13830No70
25230No70
33830Yes70
4 5230Yes70
53850Yes50
63870Yes30

Figure 2-7 depict SEM images of paper weights from Examples 1-6, respectively.

Sheets of paper were made using the paper mass, a composition in accordance with Examples 1-4, above.

The final content of calcium carbonate in each sheet of paper was equal to 20%of calcium carbonate was added to the thoroughly mixed paper pulp according to the present invention, as a result the content STMR was 8.6% of the total number (namely, about 10,75% of the paper pulp).

For the formation of a sheet of paper was added a mixture of 80% by weight of CELIMO from solid wood and 20% of the mass of CELIMO from softwood, treated up to 25°SR. The density of the leaves was 78-80 g/m2.

On these sheets of paper were tested by accelerated aging. Aging under the action of light and environmental conditions is a relatively slow process, and to assess the stability of paper pulp or paper to the action of light should be used accelerated test. It is known that artificial aging can be used to assess the stability of the group of paper grades and the comparative classification (Nordic Pulp and Paper Research Journal, 1998, 13(3), 191-197). Table SUNTEST apparatus for the production of Original HANAU was used for the study of accelerated aging of paper according to the present invention.

Made two control paper pulp: T1, containing 30% STMR at 38°SR and 79% of precipitated calcium carbonate produced under the name Megafill®(Speciality Minerals France), and T2 containing 30% STMR at 52°SR and 70% Megafill®. Sheets of paper were made from the reference paper of the masses of T1 and T2 under the same conditions as described above for paper masses 1-4. The amount of precipitated calcium carbonate and STMR were the same in the case of T1 and Examples 1 and 3 and in the case of T2 and Examples 2 and 4, the only significant difference was that in one case (controls T1 and T2) of precipitated calcium carbonate were divided on the sheet randomly, and in the other case (the subject of the present invention) was crystallised in the fibers of the paper pulp STMR.

Table 2 shows the decrease of the index of CIE whiteness index (CIE whiteness was determined according to international standard ISO 11475) after 60 minutes and 180 minutes after treatment in the device SUNTEST sheets of paper obtained using test paper mass T1 and T2 and paper weights from Examples 1-4.

Table 2
Used paper pulp
T113T224
ΔCIE 60 minutesthe 13.48,689,99of 13.058,79there is a 10.03
ΔCIE 180 minutes19,9512,6715,9218,9812,9114,97

Fig shows the change in the index of CIE whiteness as a function of exposure time (t) in the SUNTEST apparatus in minutes for paper received from the paper mass 1-4 and T1-T2. These results indicate that the paper according to the present invention have found a smaller reduction in white compared to the control, which was equal to approximately 3-8 items index CIE after 60 minutes and 4-7,5 points CIE after 180 minutes.

Fig.9 shows the change in the index of CIE whiteness as a function of exposure time (t) in the SUNTEST apparatus in minutes for paper received from the paper of masses 1 and 2 (filtered lime) and 3 and 4 (ground limestone). These results show that were found to influence the crushed lime on white paper. The initial increase in white is about 10 points index CIE, which is a significant improvement.

In the following example, compared the characteristics of permanent the minute paper mass 3, 5 and 6. This was done by making sheets of paper containing 80 mass % of the paper mass 3, 5 or 6 and 20% of a mixture of paper mass CELIMO of hardwoods and softwoods (in a ratio of 80/20), purified up to 25°SR. These sheets were subjected to a test for accelerated aging as described above, using a desktop device SUNTEST production of Original HANAU.

Table 3 shows the decrease in whiteness CIE obtained after 60 minutes of exposure in the SUNTEST apparatus for sheets of paper, manufactured using paper mass 3, 5, and 6.

Table 3
Used paper pulp
356
ΔCIE 60 minutes12,415,019,5

Thus, it can be seen that with increasing content of caso3deposited on STMR, the decrease in whiteness CIE during irradiation in the test device SUNTEST decreased; caso3deposited on the fibers, performs a protective role, preventing the yellowing of lignin.

The influence of the content of caso3deposited on STMR shown in Figure 10, which depicts the change in the index of CIE whiteness as a function of exposure time (t) in the device SUTEST in minutes for paper, obtained from the paper of the masses 3, 5, and 6.

The second series of examples

In the following examples as a starting product for the reaction of precipitation (deposition) of calcium carbonate were used in a variety of mechanical paper pulp. Reaction conditions were similar to that described above, in other words, the dispersion of hydrated lime containing 25% dry matter (slaked lime extra white varieties LYS-Polienas production company BALTHAZARD & COTTE) and 1% Coatex GSN (production company COATEX) as dispersant additives were diluted to obtain a dry matter content equal to 13%, and then filtered through a sieve with a mesh size of 100 microns. This crushed lime on microsurvey the DYNO®-Mill type KLD-Pilot to obtain particles with an average diameter of 5 microns.

The reaction was performed in a tubular reactor with a length of 52 m and a diameter of 10 mm, equipped with two static mixers, with the following parameters:

- The percentage of hydrated lime/STMR = in sufficient quantities to obtain ratios of caso3/STMR equal to 70/30,

Percent dry matter content prior to injection CO22,5%,

- The reaction pressure of 4 bar

The pressure of CO26 bar

The reaction rate of 2 l/min,

The reaction temperature of 25°C

- The volumetric rate of CO26 l/min,

- the pH at the outlet of the reactor 6,.

Used original paper pulp and their characteristics are summarized in Table 4.

td align="center"> Spruce
Table 4
Mechanical paper pulpCaso3
ExampleThe name of the paper pulpProviderGrade°SR%Crushed%
7Temcell Birch BulkTENGESBirch2430Yes70
8Temcell 325/85TENGESSolid wood3830Yes70
9Temcell 250/85 HWTENGESSolid wood4330Yes70
10325-85-100MILLAR WESTERNSolid wood3830Yes70
11CA 783ROTTNEROS ABSolid wood3230Yes70
12100 / 80gSÖDRA7030Yes70
13Cell AB.C 150/78WAGGERYD ABSoft wood6230Yes70
14HT Tissue 001SCA (Ostrand) ABSoft wood2430Yes70
15RHZZUBIALDEPine radial5830Yes70
16Sphinx 500/80M-REALSpruce2530Yes70
178255RONDCHATELSpruce5230Yes70

11-21 show the SEM-pictures of paper mass according to the Examples 7-17, respectively.

Paper pulp 7-17 were used for the manufacture of sheets of paper containing 80 mass % of the paper mass 7-17 and 20% of a mixture of paper mass CELIMO of hardwoods and softwoods (in a ratio of 80/20), purified up to 25°SR.

In each case, was made the appropriate checklist, containing the same type and the same number of mechanical paper pulp, the same amount of the mixture of the paper m is SS CELIMO of hardwoods and softwoods (in a ratio of 80/20), purified up to 25°SR, and precipitated calcium carbonate produced under the name Megafill®(Speciality Minerals France), in the amount equivalent to the amount contained in the sheets, made of paper mass according to the present invention. If checklists precipitated calcium carbonate randomly distributed across the sheet while the sheet according to the present invention it is crystallized on the fibers of mechanical paper pulp.

As in the previous examples, these sheets were tested with accelerated aging using a desktop device SUNTEST production of Original HANAU.

Table 5 shows the decrease in whiteness CIE obtained after 60 minutes of exposure in the SUNTEST apparatus, sheets of paper, manufactured using paper mass 7-17, and the relevant checklists.

Table 5
Used paper pulpΔCIE whiteness after 60 minutes
Example 713,5
Example 7 control18,3
Example 811,1
Example 8 control14,9
Example 912,6
Example 914,8
13,3
Example 10 control14,9
Example 1110,0
Example 11 control12,3
Example 1213,6
Example 12 control14,7
Example 1312,4
Example 13 control13,6
Example 1416,0
Example 14 control19,3
Example 1514,2
Example 15 control17,1
Example 1610,2
Example 16 control16,3
Example 177,8
Example 17 control11,2

These results indicate that the paper is made from paper mass according to the present invention, detects a smaller reduction in white, compared with the corresponding controls, regardless of the type used in mechanical pulp (different varieties of hard and soft wood and various kinds of processing). Caso3precipitated on the fibres, really play a protective role against yellowing of lignin.

1. Bleached mechanical pulp based fibrillated fibers of cellulose, hemicellulose and l is Gunina, containing calcium carbonate, characterized in that the calcium carbonate crystallized and at least partially covers the fibrillated fibers of cellulose, hemicellulose and lignin, with which the calcium carbonate is connected mechanically.

2. Paper pulp according to claim 1, characterized in that its total dry matter contains more than 20 wt.% the calcium carbonate of the total dry matter content.

3. Paper pulp according to claim 2, characterized in that its total dry matter contains more than 30 wt.% the calcium carbonate of the total dry matter content.

4. Paper pulp according to claim 2, characterized in that its total dry matter contains 50 wt.% or more of calcium carbonate from the total dry matter content.

5. Paper pulp according to any one of claims 1 to 4, characterized in that the calcium carbonate crystallizes in the cubic form.

6. Paper made from paper pulp, as defined in any one of claims 1 to 5, possibly mixed with other paper mass.

7. Method for the production of paper pulp, as defined in any one of claims 1 to 5, comprising the following stages: (a) forming a homogeneous aqueous suspension by mixing pre-bleached mechanical pulp based fibrillated fibers of cellulose, hemicellulose and lignin in the aquatic environment with the value for the Shopper Riggler equal, IU the greater extent, 22°and lime; (b) if the dry matter content of the suspension obtained in stage (a), more than 10 wt.% - dilution of the specified suspension until such time as the suspension obtained will not contain the proportion of dry matter less than 10 wt.%, preferably less than 5 wt.%; (b) adding carbon dioxide by injection into the above suspension in the mixing process specified suspension and maintain its temperature in the range between 10 and 50°until complete conversion of the lime into calcium carbonate crystallized in situ.

8. The method according to claim 7, characterized in that the lime used in stage (a), has the form of particles with an average diameter of less than 9 μm, preferably equal to 5 microns.

9. The method according to claim 7, characterized in that stage (a) is preceded by a stage of wet grinding is used lime.

10. The method according to claim 7, characterized in that stage (a) and (b) last for at least 30 minutes

11. The method according to claim 7, characterized in that stage (a), (b) and (C) are carried out in the tubular reactor of the type equipped with static mixers, in a continuous process.

12. The method according to claim 7, characterized in that the paper pulp used in stage (a)is bleached chemicomechanical paper weight.



 

Same patents:

FIELD: pulp and paper industry; methods of production of the pigment for manufacture of the cardboard and paper.

SUBSTANCE: the invention is pertaining to the method of production of the pigment for manufacture of the cardboard and paper and may be used in pulp and paper industry at production of the filled paper, the coated paper and the cardboard. Calcium carbonate is treated with aluminum sulfate in the aqueous medium. The treatment is conducted at aluminum sulfate consumption of 25-105 % to the mass of absolutely dry calcium carbonate at the temperature of 80-85°С during 90-180 minutes with production of the suspension containing 25-35 % dry substances in it. At that they use the aqueous medium containing the binding chosen from the group, which includes starch and polyvinyl alcohol in the amount of 0.5-3.0 mass % from the mass of the absolutely dry pigment, and-or the water soluble colorant in the amount of 0.1-0.5 mass % from the mass of the absolutely dry pigment. The suspension is additionally dried and grinded. The technical result of the invention is the improved quality of the pigment as well as expansion of its field of application.

EFFECT: the invention ensures the improved quality of the pigment as well as expansion of its field of application.

2 tbl

FIELD: pulp and paper industry; methods of production of the pigment for manufacture of the cardboard and paper.

SUBSTANCE: the invention is pertaining to the method of production of the pigment for manufacture of the cardboard and paper and may be used in pulp and paper industry at production of the filled paper, the coated paper and the cardboard. Calcium hydroxide suspension is treated with aluminum sulfate solution in the aqueous medium at stirring. The treatment is conducted in the aqueous medium containing the binding in the dissolved state. The binding is chosen from the group, which includes starch and polyvinyl alcohol in the amount of 0.5-5.0 mass % from the mass of the absolutely dry pigment, and-or the colorant in the amount of 0.1-0.5 mass % from the mass of the absolutely dry pigment. The technical result of the invention is the improved quality of the pigment and expansion of its field of application.

EFFECT: the invention ensures the improved quality of the pigment and expansion of the field of its application.

2 tbl

FIELD: pulp and paper industry; methods of production of the composite pigment for manufacture of the cardboard and paper.

SUBSTANCE: the invention is pertaining to the method of production of the composite pigment for manufacture of the cardboard and paper and may be used in pulp and paper industry at production of the filled paper, the coated paper and the cardboard. Calcium hydroxide is mixed with kaolin and added with aluminum sulfate in the aqueous medium at stirring. The aqueous medium contains the binding chosen from the group, which includes starch and polyvinyl alcohol in amount of 1.5-5.0 % from the mass of the absolutely dry pigment, and-or the water soluble colorant in amount of 0.1-0.5 % from the mass of the absolutely dry pigment. The technical result of the invention is the improvement of the composite pigment quality and expansion of its field of application.

EFFECT: the invention ensures improvement of the composite pigment quality and expansion of the field of its application.

2 tbl

FIELD: pulp and paper industry; methods of production of the pigment for manufacture of the cardboard and paper.

SUBSTANCE: the invention is pertaining to the method of production of the pigment for manufacture of the cardboard and paper and may be used in pulp and paper industry at production of the filled paper, the coated paper and the cardboard. In the water at intense stirring feed powders of calcium hydrate and calcium carbonate at the ratio of the indicated components accordingly from 1.0:2.2 up to 1.0:12.9. The produced suspension is gradually added with aluminum sulfate at its ratio to the total mass of the calcium hydroxide and calcium carbonate from 1.0:0.85 up to 1.0:4.30. Then the temperature of the mixture is increased up to 8О-85°С and the produced reaction mixture is kept at stirring within 90-180 minutes with formation of the dispersion of the pigment with the share of the dry substances in it equal to 20-35 %. Then the dispersion is dried and grinded into the powder. The powder is dispersed in the water containing the given amount of the dissolved coolant and-or binding - starch or polyvinyl alcohol. The technical result of the invention production of the pigment with the new properties, that allow to expand the field of its application at manufacture of various types of the cardboard and the paper.

EFFECT: the invention ensures production of the pigment with the new properties, expansion of the field of its application at manufacture of various types of the cardboard and the paper.

2 tbl

The invention relates to a method of filling calcium carbonate cellulose fibers, filled with paper and method of making filled paper of cellulose fibers

The invention relates to the production of compositions for paper sizing and can be used in the paper industry

The invention relates to a method for producing cardboard with a coating for packaging liquids belonging to the type that uses a sizing dispersion containing the water dispersion of rosins, synthetic sizing agent and aluminum connection

The invention relates to the pulp and paper industry

The invention relates to aqueous compositions sizing agent and method for producing paper

FIELD: production of paper and paper products in pulp-and-paper industry.

SUBSTANCE: method involves adding effective amounts of at least one cation-active polymer coagulant or inorganic coagulant with following adding of material consisting of microparticles, wherein pulp contains cellulose produced at least partly from processed paper products. Coagulant used is of natural or synthetic origin. Material based on microparticles is, for example, bentonite clay, network polymer, colloidal silicon, or polysilicate.

EFFECT: increased efficiency in reducing of white resin sedimentation.

17 cl, 2 dwg, 2 ex

FIELD: production of paper and paper products in pulp-and-paper industry.

SUBSTANCE: method involves adding effective amounts of at least one cation-active polymer coagulant or inorganic coagulant with following adding of material consisting of microparticles, wherein pulp contains cellulose produced at least partly from processed paper products. Coagulant used is of natural or synthetic origin. Material based on microparticles is, for example, bentonite clay, network polymer, colloidal silicon, or polysilicate.

EFFECT: increased efficiency in reducing of white resin sedimentation.

17 cl, 2 dwg, 2 ex

FIELD: production of paper and paper products in pulp-and-paper industry.

SUBSTANCE: method involves adding effective amounts of at least one cation-active polymer coagulant or inorganic coagulant with following adding of material consisting of microparticles, wherein pulp contains cellulose produced at least partly from processed paper products. Coagulant used is of natural or synthetic origin. Material based on microparticles is, for example, bentonite clay, network polymer, colloidal silicon, or polysilicate.

EFFECT: increased efficiency in reducing of white resin sedimentation.

17 cl, 2 dwg, 2 ex

FIELD: production of cardboard for manufacture of packages for liquids.

SUBSTANCE: method involves treating fibrous mass designated for preparing of cardboard with percarbonic acid used in an amount of 0.5-5 kg per t of dry fibrous mass on conversion to 100%-concentration of percarbonic acid; thereafter or simultaneously with indicated treatment process, providing gluing-through by combining resin-based and neutral adhesives; forming cardboard.

EFFECT: reduced moisture-permeability and improved quality of gluing-through of cardboard.

11 cl, 3 tbl, 3 ex

FIELD: production of cardboard for manufacture of packages for liquids.

SUBSTANCE: method involves treating fibrous mass designated for preparing of cardboard with percarbonic acid used in an amount of 0.5-5 kg per t of dry fibrous mass on conversion to 100%-concentration of percarbonic acid; thereafter or simultaneously with indicated treatment process, providing gluing-through by combining resin-based and neutral adhesives; forming cardboard.

EFFECT: reduced moisture-permeability and improved quality of gluing-through of cardboard.

11 cl, 3 tbl, 3 ex

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