Reinforcing paper agent and method of hardening paper (options)


D21H23/26 - by selecting point of addition or moisture content of the paper

 

(57) Abstract:

The invention relates to the pulp and paper industry. Reinforcing paper agent contains a water dispersion of a polymer obtained by polymerization of a monomer composition containing a (meth)acrylic acid, and deposition of the resulting polymer in the form of fine particles, and which is introduced into the paper layer after paper layer is formed, in which: concentration (co)polymer of (meth)acrylic acid in the specified polymer dispersion is not less than 5% wt.; average particle diameter (co)polymer of (meth)acrylic acid in the specified polymer dispersion is 1-100 μm; the specified viscosity polymer dispersion immediately after receipt and after 1 month of receipt is 30-5000 mPas; polymer particles can be identified when this polymer dispersion is diluted 10 times with distilled water, and the diluted dispersion is observed under a microscope with 400x magnification; and these polymer particles are dissolved with the formation of an aqueous solution when the pH of the specified diluted dispersion is adjusted to 7.0 by adding alkali. Reinforcing paper agent obtained in this way, allow the surface to dry paper or the surface of the raw paper, and drying the treated paper. 4 C. and 9 C. p. F.-ly, 5 PL.

The present invention relates to reinforcing paper agent containing a dispersion of fine particles of water-insoluble polymer obtained by polymerization of a monomer containing methacrylic acid in aqueous solution, and deposition of the resulting polymer, which (hardening paper agent) is introduced into the paper layer after paper layer is formed in the process of getting the paper, and relates to a method of hardening the paper, in which low-viscosity polymer dispersion obtained by diluting this hardening paper agent water saturates the paper during spraying or application.

Posted Japanese application N 62-20511 considers a method of obtaining a dispersion of water-soluble polymer by the polymerization of monomer in the aqueous salt solution, which dissolves the monomer and does not dissolve the formed polymer in the presence of the polymer electrolyte.

On the other hand, Japanese laid out application N 60-185900 considers a method of obtaining a dispersion of fine particles of a polymer by the polymerization of acrylic acid with acrylamide in aqueous salt solution, which dissolves the monomers but does not dissolve the formed polymer. the TA. Fine polymer particles obtained herein are water-insoluble and soluble in the solvent, if the dispersion is neutralized, i.e. this technology differs from the one proposed in Japanese laid out the application N 62-20511. However, fine particles in a dispersion of a copolymer of acrylic acid and acrylamide glomerida, giving a deposition in the form of grains of curd and having therefore the disadvantage of being unsuitable for storage for long periods of time.

The technical task of the present invention is to increase the punching shear resistance, ring of strength crush strength and surface strength of paper, such as wax pic, due to the efficient impregnation of the paper layer of high molecular weight polymer.

Another technical task of the present invention is to increase the interlayer adhesion strength of paper when adgezirovannah high molecular weight polymer to a multitude of surfaces of thin sheets.

It was found that the dispersion of fine polymer particles having a low viscosity, good processability and excellent storage stability can be obtained by polymerization monotony polymer electrolyte, with the deposition of the obtained polymer. In addition, during a series of different attempts to find a use for this variance, the authors present invention also found that this dispersion shows such remarkable effects as hardening of paper when applying the specified dispersion on dry paper using a size press, install with adjustable rolls or installation with a doctor blade, etc., hardening of paper impregnation specified paper coating on wet paper on the mesh and reinforcement interlayer adhesion of paper when adgezirovannah of the specified polymer dispersion on a variety of surfaces, thin sheets, which results in the present invention.

A technical problem solved by creating a reinforcing paper agent containing the water dispersion of a polymer obtained by polymerization of a monomer composition containing a (meth) acrylic acid, for introduction into the paper layer after its formation, which according to the invention, contains a specific polymer in the aqueous dispersion obtained his deposition in the form of fine particles, in which:

- concentration (co)polymer of (meth)acrylic acid in the specified polymer dispersion sostoi dispersion is 1-100 microns;

the specified viscosity polymer dispersion immediately after receipt and one month after receipt of 30 to 5000 mPas;

polymer particles can be identified when this polymer dispersion is diluted 10 times with distilled water, and the diluted dispersion is observed under a microscope with magnification of 400x, and

- these polymer particles are dissolved with the formation of an aqueous solution when the pH of the specified diluted dispersion is adjusted to 7.0 by adding alkali.

The polymer dispersion may polymerization and precipitate in the presence of supporting dispersibility agent containing polyvalent electrolyte.

It supports dispersibility agent is selected from cationic polyelectrolyte, surfactant, having a polyvalent cationic hydrophilic group and a hydrophobic group, and mixtures thereof.

In addition, the mass ratio of monomer composition containing a (meth)acrylic acid in aqueous solution to support dispersible agent may be from 100:1 to 10:1, and viscosity of the specified polymer dispersion immediately after receipt and after 1 month is taken copolymer of dimethyldiallylammonium, or polyethylenepolyamine, replaced by accelgroup and/or arlbergpass, pentamethylenebis, replaced by accelgroup and/or arlbergpass, and altergroup has at least 5 carbon atoms.

In addition, the technical problem solved by the creation of a method of hardening the paper, including the dilution of reinforcing paper agent with water, the coating or impregnation diluted hardening agent paper and drying the paper, which according to the invention proposed strengthening the paper, the agent is diluted with water to form a diluted dispersion, and deposition or impregnation of the diluted dispersion is subjected to dry paper.

Technical problems are also solved by the creation of a method of hardening the paper, including the dilution of reinforcing paper agent water and impregnation diluted hardening agent paper, which according to the invention proposed strengthening the paper, the agent is diluted with water to form a diluted dispersion, and the impregnation of the diluted dispersion is subjected to wet paper on the mesh.

This indicated the diluted dispersion is sprayed in order to impregnate the raw paper.

Furthermore, this raw paper treated with the indicated rasb the hardening of paper, including dilution reinforcing paper agent with water and spraying the diluted agent on the paper, in which, according to the invention, the proposed strengthening the paper, the agent is diluted with water to form a diluted dispersion, which is sprayed on the surface of a thin sheet with many thin sheets with polymer adhered to their surfaces, and on the surface of these thin sheets of pressed when the overlay them on each other, followed by drying.

The monomer, which contains methacrylic acid used in the present invention, is a mixture of 5-50 mol%. acrylic acid, methacrylic acid or mixtures thereof, and the basis of itaconic acid and/or acryloyldimethyltaurate, etc., in the interval, which gives a lower degree of polymerization or no harmful effects on the solubility, and 50-95 mol%. one type of nonionic monomer selected from the group consisting of methacrylamide, Methacrylonitrile, N-vinylcarbazole, N-isopropylacrylamide, N, N-dimethylacrylamide, methyl methacrylate, hydroxyethylmethacrylate, vinylmation simple ether, vinyl acetate, styrene and mixtures thereof.

The cationic monomer may polymerization in the polymer can be achieved by dilution with distilled water.

Among them, most preferred is a monomer composition that contains 5-50 mol%. methacrylic acid, 50-95 mol%. methacrylamide and 0-50 mol%. Methacrylonitrile.

It is preferable to conduct the polymerization in the presence of supporting dispersibility agent to obtain a polymer dispersion of the present invention. Examples of supporting dispersibility agent containing a cationic polymer electrolyte used in the present invention are copolymers of salts or Quaternary products dialkylaminoalkyl, copolymers of salts or Quaternary products dialkylaminoalkyl and copolymers dialkyldimethylammonium salt.

Examples of salts or Quaternary products dialkylaminoalkyl include dimethylaminoethylmethacrylate and acryloyldimethyltaurate. Examples of salts or Quaternary products dialkylaminoalkyl include hydrochloride or methylated products dialkylaminoalkyl. Example dialkyldimethylammonium salt is dimethyldiallylammonium.

Can be used not only one type, but also a mixture of S="ptx2">

Cationic water-soluble polymer may be a homopolymer or a copolymer with a non-ionic monomer, such as acrylamide.

Especially preferred water-soluble cationic polymer is a copolymer of dimethyldiallylammonium.

An example supporting the dispersibility agent containing a surface-active agent having a polyvalent cationic hydrophilic group and a hydrophobic group used in the present invention, is substituted polyethylenepolyamine, in which at least one hydrogen atom at its nitrogen atom substituted by accelgroup and/or arlbergpass. Effective is the product pentachloroaniline, replaced by altergroup having at least 5 carbon atoms in the specified altergroup.

The mass ratio of monomer that contains methacrylic acid, to support dispersible agent is, preferably, from 100: 1 to 10:1. If the number of supporting dispersibility agent is too small, dispersion of precipitates in the form of grains of curd. On the other hand, excessive introduction supporting dispersibility agent is economically meaningless.

Below is ESU.

The introduction of supporting the dispersibility of the agent at the specified interval viscosity polymer dispersion is maintained in the range from 30 to 5000 mPas immediately upon receipt and within a month after receipt and is stable for a long time.

The product, having a viscosity of from 30 to 1500 mPas is preferable in terms of handling when considering the convenience in the application process.

Since the polymer dispersion of the present invention uses the multivalent cationic compound as supporting dispersible agent, the surface energy of the polymer particle is cationic, and it can be also mixed with an aqueous solution of water-soluble cationic polymer and a water dispersion.

Aqueous salt solution can also be used in the present invention for the purpose of promotion of the deposition of the polymer. Examples of salt, which forms a specified aqueous salt solution include alkali metal salts such as sodium salt and potassium salt, and ammonium salts such as ammonium chloride, ammonium sulfate and ammonium nitrate. The concentration and pH of the specified aqueous salt solution should be areeda. On the contrary, it is necessary to support dispersible agent, which is also present, was soluble in aqueous salt solution.

Dispersion of a copolymer of methacrylic acid and supportive dispersible agent in the present invention, respectively, can be obtained by dissolving the monomer (monomers) in the aquatic environment in a nitrogen atmosphere without oxygen and a radical polymerization monomer (monomers) with the introduction of a water-soluble polymerization initiator azo-type, such as 2,2'-azobis(2-amidinopropane) hydrochloride, or a water-soluble polymerization initiator of the redox type, used as ammoniumsulfate, and sodium bisulfite.

The temperature of the polymerization system can be freely selected depending on properties of the used initiator of polymerization in the range from 0 to 100oC.

To regulate the molecular weight of the obtained polymer may be injected control degree of polymerization, such as isopropyl alcohol or mercaptan, and used for an arbitrary choice in the same way as in conventional radical polymerization.

While obtaining a dispersion of a copolymer of methacrylic acid should p the polymer particles. The upper limit of the speed of mixing is absent, and can be selected from any of the conditions of mixing, provided that the content is not flowing from the equipment.

Despite the fact that obtaining support dispersible agent is usually carried out by stationary polymerization in aqueous solution, its polymerization in the present invention, preferably, is carried out under stirring, from the point of view of homogenization of products.

The concentration of polymer in the dispersion of the present invention is high or not less than 5% wt. and typically ranges from 5% wt. up to about 40% wt

Despite the fact that the dispersion of the present invention contains a high concentration of the formed polymer, the viscosity of the dispersion is low, usually 30-5000 mPas, and preferably 30-1500 mPas, since the polymer is stably dispersed in the dispersion medium in the state of fine particles. Therefore, as their characteristics polymer dispersion can easily flow and can be handled very easily.

Polymer particles in the dispersions of the present invention can be identified in the undiluted state and in dilute state in the Proc. of the polymer particles is typically 1-100 μm, preferably 2-50 μm and, more preferably 2-30 μm. When the average diameter of the polymer particles exceeds 100 μm, because the particles tend to easily deposited, the stability of the deposition is broken. In addition, the solubility also deteriorates during use due to the large size of the polymer particles even when mixed with water, so it takes a long time for complete dissolution of the polymer. On the contrary, the dispersion of the present invention has excellent stability of the deposition, and any violation of such as adgezirovannah particles to each other with the formation of the lumps, not even during storage at normal temperatures. In addition, its solubility in the process of applying is extremely good.

The molecular weight of the polymer in the dispersion of the present invention is not specifically limited. If the dispersion of the present invention is determined by the viscosity of the solution when dissolved in 2% wt. aqueous salt solution of ammonium sulfate (viscosity measured at 25oC using Brookfield viscometer) so that the concentration of the polymer becomes 0,5% (viscosity) is usually in the range from 5 to 200 mPas. Moreover, the var is of one month.

When the dispersion of the present invention is diluted 10 times, the polymer particles can be identified with a microscope, and when the dispersion of alkali is added to adjust the pH of the dispersion to 7.0, these polymer particles are dissolved with the formation of aqueous solution, i.e. we can say that the variance of the present invention is a dispersion of fine particles of water-insoluble polymer.

In the present invention the effects of hardening of the paper obtained by coating or impregnation of water diluted dispersion of the specified reinforcing paper agent on the surface with a dry paper or damp paper, followed by drying.

In the method of hardening the paper of the present invention reinforcing paper agent may be used in combination with other chemical raw end, for example, holding additive for fillers or drainage additive. More precisely, an aqueous solution of cationic starch, cationic polyacrylamide or other hardening agent wet end of the paper, etc. is introduced and mixed with the paper material, and the diluted aqueous dispersion hardening paper agent according to the present invention deposited on si sucking with providing paper impregnation specified as water dispersion.

In another embodiment according to the present invention after drying, made of paper, polymer-impregnated surface and the inner part of the paper when applying the diluted aqueous dispersion hardening paper agent of the present invention the obtained dry paper using a size press, install with adjustable rollers, installation, doctor blade, etc.

Almost all the amount of polymer deposited according to this method, remains in the paper, namely the sheet of pulp. Due to the adhesion of the fibers of the pulp, and so on, it is possible not only to increase the surface strength of paper, but also the resistance to bursting and the annular crushing strength.

Paper, in which the reinforcing paper agent is introduced for these are not raw ends, often used for printing paper, paper for recording apparatus and a copying paper (PPC paper), and the leaves are usually a single layer.

On the contrary, in the production of paperboard many thin sheets is usually combined with each other. When spraying a diluted aqueous dispersion hardening paper agent of the present invention on the surface of a thin sheet of many thin sheets of adhesionand the ug on the other, the strength of the paper, such as interlayer adhesive strength of paper multiple laminated sheets of paper can be increased, making it possible to prevent delamination.

In addition, reinforcing paper agent of the present invention can also be used in traditional prevents exfoliation agents such as starch, modified starch, casein and galactomannan.

The present invention differs in that the polymer containing a water-soluble monomer containing methacrylate, not used.

Methacrylic copolymer is refractory and has a low viscosity, despite the fact that the molecular weight is high, ensuring that even highly concentrated dilute aqueous dispersions are easily applied to the surface.

According to the present invention, high molecular weight polymer can be effectively applied in a water-insoluble condition. As pH increases, when the paper is soaked applied polymer portion of the polymer becomes water-soluble and turns into a paste-like substance. Accordingly, it is expected that it acts as an adhesive.

When considering properties in image quality compared with the aqueous solution of the methacrylate copolymer. Therefore, there is no difficulty in coating raw paper, and is not observed uneven floor surface dry paper.

In the method of the present invention the polymer dispersion is sprayed or applied to the surface after dilution to the concentration of the polymer is 0.1-0.5% wt.

The amount of polymer introduced into the paper during spraying or application, is the net amount of the polymer of 0.05-1.0% by weight. on suspended dry pulp, and is, preferably, 0.1 to 0.5 wt.%

EXAMPLES

Although the following provides a detailed description of the present invention through its examples, the present invention is not limited to the following.

Example obtain 1

In a reactor equipped with a stirrer, a pipe, a nitrogen purge and a temperature controller, 10 o'clock Monomeric composition consisting of 15 mol%. of acrylic acid, 35 mol%. acrylamide and 30 mol%. Acrylonitrile, and 1 tsp of polydimethyldiallylammonium as a dispersant (manufactured by the firm Sipes To. brand: Age Flock WT40HV) was dissolved in 89 hours deionized water. Then as the polymerization initiator is introduced 2,2'-azobis[2-(imidazolin-2-yl) propa is held with stirring for 20 h at 35oC to obtain a polymer dispersion (pH 3), in which the dispersed fine particle size of 5-50 μm. This dispersion is designated "Sample-1".

The specified viscosity polymer dispersion (Sample - 1) is equal to 1000 mPas, fine particles successfully identified under the microscope even after diluting 10-fold with distilled water, and actually confirmed that the polymer is water-insoluble. With this dispersion is mixed aqueous solution of sodium carbonate to adjust the pH of the dispersion to 7, after which the polymer is dissolved and determined its molecular weight by the characteristic viscosity of the specified water solution.

Example of getting 2

Repeats the example of obtaining 1, except that the used monomer composition consisting of 30 mol%. of acrylic acid, 45 mol%. acrylamide and 25 mol%. Acrylonitrile, obtaining a dispersion of water-insoluble polymer. This dispersion is designated "Sample-2".

Example of getting 3

In a reactor equipped with a stirrer, a pipe, a nitrogen purge and a temperature controller, 20 hours Monomeric composition consisting of 30 mol%. of acrylic acid, 60 mol%. acrylamide and 10 mol%. Acrylonitrile, and 1 is CA: Age Flock WT40HV) was dissolved in 79 hours an aqueous solution of sodium chloride having a concentration of 20 wt.%. Then as the polymerization initiator is introduced 2,2'-azobis(2-amidinopropane)dihydrochloride (manufactured by the firm of WAKO pure chemical industries, Ltd., brand V-50). Polymerization is conducted with stirring for 10 h at 53oC to obtain a polymer dispersion (pH 3), which in aqueous salt solution dispersed fine particle size of 10-20 microns. This dispersion is designated "Sample-3".

The specified viscosity polymer dispersion (sample-3) is equal to 500 mPas or less, the fine particles successfully identified using a microscope even after dilution of the indicated dispersion 10 times with distilled water, and actually confirmed that the polymer is water-insoluble.

An aqueous solution of sodium carbonate is mixed with the above dispersion to adjust the pH of the dispersion to 7, after which the polymer is dissolved and determined its molecular weight by the characteristic viscosity of the specified water solution.

Example 4

In a reactor equipped with a stirrer, a pipe, a nitrogen purge and a temperature controller, 20 hours monomer composition containing the chloride is added to pentamethylenebis as a dispersant, dissolved in 79 hours of an aqueous solution of sodium chloride having a concentration of 20 wt.%. Then as the polymerization initiator is introduced 2,2'-azobis(2-amidinopropane)dihydrochloride (manufactured by the firm of WAKO pure chemical industries, Ltd., brand: V-50). Polymerization is conducted with stirring for 10 h at 53oC to obtain a polymer dispersion (pH 3), which in aqueous salt solution dispersed fine particle size of 10-20 microns. This dispersion is designated "Sample-4".

The specified viscosity polymer dispersion (Sample - 4) is equal to 500 mPas or less, the fine particles are successfully identified in the specified dispersion with a microscope even after diluting 10-fold with distilled water, and in fact can be certified that the polymer is water-insoluble. An aqueous solution of sodium carbonate is mixed with the above dispersion to adjust the pH of the dispersion to 7, after which the polymer is dissolved, and determined its molecular weight by the characteristic viscosity of the specified water solution.

Polymer characteristics of the Sample-1, Sample 2, Sample 3 and Sample 4 are shown in table 1.

Determination of the influence of surface p is izbavlenii water dispersion, having a polymer concentration of 2.0%. This diluted dispersion is applied to a commercially available medium quality paper (the main mass of 55 g/m2the manufacturer - Daishowa paper Co., Ltd., a neutral paper) using causing rod or roll, dried for 5 min at 105oC with getting covered with paper. The amount deposited polymer are equal to 0.1 g/m2and 0.2 g/m2.

The results of determining the punching shear resistance and surface strength of the paper are given in table 2.

Determination of the influence of surface coating-2

The polymer dispersion of this example is diluted with acidified water with pH 3, followed by the introduction of acid starch with obtaining the applied liquid having a polymer concentration of 2.0% and the concentration of acid starch and 2.0%. This caused the liquid is applied on medium quality paper having a basic weight of 60 g/m2using installation with adjustable rolls, followed by drying to obtain coated paper. The amount deposited polymer are equal to 0.1 g/m2and 0.2 g/m2.

The results of the tests on the punching shear resistance and surface strength are tablg agents of the present invention, can be easily printed on paper in the form of a diluted dispersion having low viscosity and good processability, and are able to provide a paper having high strength.

Determination of hardening the deposited securities

Scrap corrugated cardboard on the ground roll type Niagara, and its crushing ratio is adjusted to 400 ml in Canadian standard C. S. F. obtaining pulp. To this slurry is added a liquid ligament to 2%, followed by stirring to obtain a homogeneous mixture. Received the paper pulp is diluted to 0.5% and is obtained raw paper A having a dry bulk of 125 g/m2and the moisture content of 96%, determined using a hand-made instrument for testing paper. Diluted dispersion of each sample having a polymer concentration of 0.25%, napylyaetsya on one side of the raw paper with a nozzle at a pressure of 2 kg/cm2in accordance with the amounts of the polymer are listed in table 4 (the content of the polymer on the dry weight of the pulp), followed by suction from the opposite side. This kind of testing in the case of deposition on the grid for forming paper from paper pulp. Then wet the paper pokeweeds determine the strength of paper.

After adjusting the moisture content of the obtained paper to determine the strength of the paper is determined resistance to the pushing ring and the crushing strength, the determination results of which are given in table 4.

Notes to table 4:

Sample "Control - A" is a commercially available hardening agent mandenovai paper for raw ends (the manufacturer - Arakawa chemical industries, Ltd. brand - Polastron 609), while sample "Control - B" is commercially available reinforcing paper agent agent type reaction Hoffman for raw ends (the manufacturer - Seiko chemical industries, Ltd., brand: Stargem FN).

The annular crushing strength: determined according to TAPPI standard T472wd-76.

Assessment

Reinforcing paper agent of the present invention can easily be sprayed in the form of a diluted dispersion with low viscosity and good processability and capable of providing a paper having good evidence of retention in paper and high strength paper without clogging the nozzle or without manifestations of uneven adhesion.

Determining prevent delamination

Prima is raised to 400 ml in Canadian standard C. S. F. obtaining pulp. Liquid bundle 2% and commercially available anionic reinforcing paper agent to 0.9% is introduced into a pulp and mixed until a homogeneous mixture. Received the paper pulp is diluted to 0.5% and is obtained raw paper A having a dry bulk 100 g/m2and the moisture content of 96%, determined using a hand-made instrument. Diluted dispersion of each sample of the present invention having a polymer concentration of 0.5%, napylyaetsya on one side of the paper using a nozzle at a pressure of 2 kg/cm2in accordance with the amounts of the polymer are listed in table 5 (the content of the polymer on the dry weight of the pulp). Therefore, covered the surface of the raw paper A is superimposed on the surface of the raw paper B, after which they are placed between the plates and pressed with the help of experienced calender and dried to obtain cardboard given combination. After adjusting the moisture content of the paperboard of this combination is determined by its strength on T-raster (g/mm) in accordance with the test method of paper J-TAPPI N 19-77. The results are given in table 5.

Comparative example

Repeat the methods of examples, except for the use of aqueous polymer solutions when regulation is used in the examples to pH 7.0 with sodium hydroxide to dissolve the polymer.

Reinforcing interlayer adhesion of paper agent of the present invention can be easily napalan in the form of a diluted dispersion having low viscosity and good processability, and is able to provide a combination paper having a high interlayer adhesion, without clogging of the nozzle or without manifestations of uneven adhesion.

Although the now preferred variants of the present invention is shown and described, it is necessary to understand that the present invention is not limited to them and that specialists can be made various changes and modifications without departing from the scope of the invention as set forth in the attached claims.

1. Reinforcing paper agent containing the water dispersion of a polymer obtained by polymerization of a monomer composition containing a (meth)acrylic acid, for introduction into the paper layer after molding, characterized in that it contains the specified polymer in the aqueous dispersion obtained his deposition in the form of fine particles, in which the concentration of (co)polymer of (meth)acrylic acid in the specified polymer dispersion sostavljae is 1 - 100 μm, the viscosity of the specified polymer dispersion immediately after receipt and one month after receipt of 30 to 5000 mPas, polymer particles can be identified when this polymer dispersion is diluted 10 times with distilled water, and the diluted dispersion is observed under a microscope with magnification of 400x, these polymer particles are dissolved with the formation of an aqueous solution when the pH of the specified diluted dispersion is adjusted to 7.0 by adding alkali.

2. Reinforcing paper agent p. 1, characterized in that the polymer dispersion is polymerized and deposited in the presence of supporting dispersibility agent containing polyvalent electrolyte.

3. Reinforcing paper agent under item 1 or 2, characterized in that the supporting dispersibility agent is selected from cationic polyelectrolyte, surfactant, having a polyvalent cationic hydrophilic group and a hydrophobic group, and mixtures thereof.

4. Reinforcing paper agent according to any one of paragraphs.1 to 3, characterized in that the mass ratio of monomer composition containing a (meth)acrylic acid in aqueous solution is according to any one of paragraphs.1 - 4, characterized in that the viscosity of the specified polymer dispersion immediately after receipt and after 1 month after receipt of 30 to 1500 mPas.

6. Reinforcing paper agent according to any one of paragraphs.1 to 5, characterized in that the supporting dispersibility agent is a copolymer of dimethyldiallylammonium.

7. Reinforcing paper agent according to any one of paragraphs.1 to 5, characterized in that the supporting dispersibility agent is a polyethylenepolyamine, replaced by accelgroup and/or arlbergpass.

8. Reinforcing paper agent p. 7, characterized in that the supporting dispersibility agent is pentamethylenebis, replaced by accelgroup and/or arlbergpass, and altergroup has at least 5 carbon atoms.

9. The method of hardening the paper, including the dilution of reinforcing paper agent with water, the coating or impregnation diluted hardening agent paper and drying of paper, characterized in that the reinforcing paper agent according to any one of paragraphs. 1 - 8 diluted with water to form a diluted dispersion, and deposition or impregnation of the diluted dispersion is subjected to dry paper.

10. The method of hardening the paper, including razbam is, is it reinforcing paper agent according to any one of paragraphs.1 - 8 diluted with water to form a diluted dispersion, and the impregnation of the diluted dispersion is subjected to wet paper on the mesh.

11. The method according to p. 10, characterized in that the diluted dispersion is sprayed in order to impregnate the raw paper.

12. The method according to p. 10 or 11, characterized in that the raw paper, processed specified diluted dispersion is a single sheet.

13. The method of hardening the paper, including the dilution of reinforcing paper agent with water and spraying the diluted agent for paper, characterized in that the reinforcing paper agent according to any one of paragraphs.1 - 8 diluted with water to form a diluted dispersion, which is sprayed on the surface of a thin sheet with many thin sheets with polymer adhered to their surfaces, and the surface of these thin sheets of pressed when the overlay them on each other, followed by drying.

Priority points:

22.04.1998 on PP.1, 10 - 12;

09.06.1998 on PP.2 to 9;

01.07.1998 on p. 13.

 

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SUBSTANCE: method includes providing a fiber-containing suspension, in which at least about 60% wt. fibers are cellulosic fibers, and dewatering the suspension on a wire mesh to form the cellulosic fibrous canvas. The method additionally comprises adding particles comprising silica and a reinforcing in the wet state agent in the moulded canvas. The present invention also relates to a product obtained by this method. The invention furthermore relates to an aqueous dispersion having a pH in the range from 2 to 7 and containing particles containing silica and the reinforcing in the wet state agent. Another aspect of the invention relates to the use of the dispersion as an additive in the papermaking process.

EFFECT: increasing strength and stiffness of the paper in the wet state.

17 cl, 3 ex, 6 tbl

FIELD: textiles, paper.

SUBSTANCE: invention relates to the pulp and paper industry and relates to napkin paper and a method of its production. The paper consists predominantly of a structure of two types of hydrophilic cellulosic fibres different in coarseness of fibres, and comprises a strength increasing additive. Two types of hydrophilic cellulosic fibres represent the first pulp, which has the fibre coarseness of from 0.13 to 0.16 mg/m, and the second pulp which has the fibre coarseness of from 0.17 to 0.20 mg/m. The difference in fibre coarseness between the first pulp and the second pulp is from 0.01 to 0.07 mg/m. The structure has a degree of fineness of 400 to 550 ml.

EFFECT: invention provides a napkin paper having good properties of strength and permeability.

18 cl, 8 dwg, 6 tbl, 4 ex

FIELD: textiles, paper.

SUBSTANCE: invention relates to paper products of sanitary and hygienic purposes, the structure of which comprises the fibrous paper web, an agent imparting a temporary wet strength, the composition of destructing agent, which comprises the destructing agent, a carrier which suppresses decomposition, and a non-ionogenic surfactant. The non-ionogenic surfactant stabilizes the viscosity of the composition over time. The composition of the destructing agent may be combined with an agent of temporary wet strength to obtain a paper product having high initial tensile strength in the wet state and the desired degradability. The invention also relates to methods of formation of a paper product and to the fluid capable of pumping the composition to decompose the agent of temporary wet strength, which is present in the structure of the fibrous web of the paper product.

EFFECT: improvement of the material.

22 cl, 1 tbl

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