JP4793997B2 - Paper making method - Google Patents

Description

The present invention relates to a papermaking method, more specifically, a diluted solution of a water-soluble polymer fine particle obtained by polymerizing a vinyl compound in a salt aqueous solution, and after dissolving at a high concentration as the water-soluble polymer concentration, Furthermore, the present invention relates to a papermaking method characterized in that a solution diluted with dilution water is added to a papermaking raw material before papermaking to make paper.

The water-soluble polymer dispersion in salt water does not use oil as a solvent, and is excellent from the viewpoint of environmental conservation. However, since it follows the process of insolubilization and precipitation in the solvent during the polymerization process, it exhibits a unique behavior when it is dissolved in water. For example, the aqueous solution viscosity is low. Although the cause of this has not been elucidated in detail, it is presumed that the water-soluble polymer may not be completely dissolved. This acts both positively and negatively depending on the purpose of use. However, when the coagulation action is taken into consideration, it is considered that the performance is improved if the water-soluble polymer is spread in water.

A water-in-oil emulsion has an appearance similar to that of a water-soluble polymer dispersion in salt water, and a study of a dissolution method is disclosed as a prior art in this product.
For example, Patent Document 1 is a method in which dilution water is mixed with an emulsion to make a primary solution, and further diluted water is mixed with the primary solution to make a secondary solution. Similarly, Patent Document 2 (Japanese Patent Laid-Open No. 2000-282391) is a two-stage dissolution method, but the dissolution method is defined by the ratio of the string length of the primary solution and the secondary solution.
JP 2001-213968 A JP 2000-282391 A

The subject of this invention is developing the useful melt | dissolution method of the water-soluble polymer dispersion liquid in salt water for the purpose of the yield improvement on the wire of the raw material in paper manufacture.

As a result of intensive studies to solve the above problems, the following invention has been achieved. That is, the invention of claim 1 is a monomer that essentially contains a cationic monomer represented by the following general formula (1) and / or (2) and (meth) acrylamide in a papermaking raw material before papermaking. In dissolving a dispersion composed of water-soluble polymer fine particles obtained by dispersion polymerization in an aqueous salt solution in the presence of a polymer dispersant that dissolves in an aqueous salt solution, the concentration of the water-soluble polymer is 0.2 to 1. The papermaking method is characterized in that, after dissolving in the range of 0.0 mass%, paper is made by adding a diluted solution after further mixing with dilution water.
General formula (1)
R1 is hydrogen or a methyl group, R2 and R3 are alkyl or alkoxyl groups having 1 to 3 carbon atoms, R4 is hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group or a benzyl group, which may be the same or different. Represents oxygen or NH, B represents an alkylene group or alkoxylene group having 2 to 4 carbon atoms, and X1 represents an anion.
General formula (2)
R5 represents hydrogen or a methyl group, R6 and R7 each represent an alkyl group having 1 to 3 carbon atoms, an alkoxy group or a benzyl group, and X2 represents an anion.

The invention according to claim 2 is the paper manufacturing method according to claim 1, wherein the water-soluble polymer has a weight average molecular weight of 10 million or more.

The invention according to claim 3 is characterized in that the water-soluble polymer concentration of the solution obtained by mixing and diluting the dilution water is 0.05 to 0.15% by mass. It is.

Invention of Claim 4 is a paper manufacturing method of Claim 1 characterized by the content of the fine fiber content in the papermaking raw material before the said papermaking being 10-40 mass%.

The papermaking method of the present invention is a polymer dispersion in which a monomer containing a (meth) acrylic and / or diallyldialkylammonium salt and (meth) acrylamide as essential components in a papermaking raw material before papermaking is dissolved in an aqueous salt solution. In dissolving a dispersion composed of water-soluble polymer fine particles obtained by dispersion polymerization in an aqueous salt solution in the presence of an agent, after dissolving in the range of 0.2 to 1.0% by mass as the water-soluble polymer concentration Further, the invention is characterized in that paper is made by adding a diluted solution mixed with dilution water.

When the weight average molecular weight of the water-soluble polymer is 10 million or more,
The effect becomes remarkable.

Moreover, it is preferable that the water-soluble polymer density | concentration of the solution which mixed and diluted the said dilution water is 0.05-0.15 mass%.

Furthermore, the effect is remarkable when the content of the fine fibers in the papermaking raw material before paper making is 10 to 40% by mass.

The solution of the water-soluble polymer dispersion in an aqueous salt solution used in the papermaking method of the present invention is prepared by the following method. That is, after dissolving in the range of 0.2 to 1.0% by mass as the water-soluble polymer concentration, a dilution solution is further mixed to obtain a dissolved solution. The concentration of the water-soluble polymer after re-dilution is 0.02 to less than 0.2% by mass, and more preferably 0.05 to 0.17% by mass.
That is, when it is actually added to the papermaking machine, there is a side effect such as soiling of the papermaking machine or disturbance of formation due to poor dispersion at a high concentration, so it is necessary to perform re-dilution. However, it is preferable to add as high a concentration as possible. However, regarding the mechanism of the effect of the present invention, it is not yet known in detail whether the yield effect is excellent when it is dissolved at a relatively high concentration without being dissolved at the concentration when added directly to the papermaking raw material, and further diluted to the added concentration It is.

A water-soluble polymer dispersion in an aqueous salt solution undergoes a process of insolubilization and precipitation in an aqueous salt solution during polymerization. Therefore, it is presumed that the water-soluble polymer in the particles takes a considerably different form from the particles of the water-in-oil emulsion product in which the polymerization proceeds in the water droplets in the oil and does not pass through the process of insolubilization. The That is, it is a state of crystallization. When it comes into contact with a large amount of diluted water, it breaks down into small crystals, but the water-soluble polymer has not yet spread into the water. On the other hand, when dissolved at a high concentration, the apparent viscosity is high and particles do not collide with each other, and water enters the particles. However, even after dilution, the dissolved state at a high concentration does not change much. Alternatively, when dissolved at a high concentration, the degree of entanglement between polymer chains is high, and this state may be maintained even after dilution. Therefore, as a result of these, it is presumed that the dissolved state of the water-soluble polymer is different between the case where it is dissolved at a low concentration from the beginning and the case where it is dissolved at a high concentration and then diluted to a low concentration.

The molecular weight of the water-soluble polymer used in the present invention thus produced is
If the weight average molecular weight by light scattering is higher than 5 million, the performance is good. Although there is no upper limit, the molecular weight is at most 20 million based on the current polymerization technology.
Therefore, the molecular weight range is 5 million to 20 million, preferably 10 million to 20 million. That is, the higher the molecular weight, the more pronounced the effect of the dissolution method according to the present invention. This is considered due to the fact that the solubility in water decreases as the molecular weight increases.

In the paper manufacturing method of this invention, it turned out that the expression of an effect changes with content of the fine fiber content in a papermaking raw material. That is, when the content of the fine fiber is 10 to 40% by mass, the effect of the present invention appears remarkably. In the present invention, the fine fiber content refers to the ratio of 200-mesh under suspended particles excluding inorganic substances such as fillers. For inorganic substances, the papermaking raw material is ADVANTECNO. Filter with 2 filter paper, incinerate at 525 ° C. after drying, measure ash, and use ash as inorganic part material.

The addition amount of the water-soluble polymer of the present invention is 20 ppm to 5000 ppm, preferably 50 ppm to 1000 ppm, more preferably 100 ppm to 500 ppm, based on the solid content of the papermaking raw material.

As a place where the water-soluble polymer is added, a fan pump inlet where the papermaking raw material is diluted with white water, a screen inlet, or the like can be considered. Further, the addition site of the cross-linked anionic water-soluble polymer may be a screen inlet or a screen outlet.

Examples of the paper product to be improved in yield and / or drainage according to the present invention include high-quality paper, medium-quality paper, newsprint, packaging paper, card base paper, liner, core base paper, or white balls.

A polymer dispersant for dissolving a cationic monomer represented by the following general formula (1) and / or (2) used in the present invention and a monomer containing (meth) acrylamide as essential components in an aqueous salt solution A dispersion composed of water-soluble polymer fine particles obtained by dispersion polymerization in an aqueous salt solution in the presence of water is a granular system produced by the dispersion polymerization method in the presence of a polymer dispersant soluble in the aqueous salt solution. It consists of polymer fine particles of 100 μm or less. The manufacturing method will be specifically described as follows. Prepare an aqueous solution of a polyvalent anion salt such as ammonium sulfate. In the case of a cationic polymer, (meth) acrylate-based quaternary ammonium base-containing monomer and acrylamide as a cationic monomer, nonionic polymer In the case of (2), acrylamide is added, or in the case of an amphoteric polymer, (meth) acrylic acid is added in addition to the above two types of monomers. The pH at this time is set to 2-6. After the mixture is uniformly dissolved, the polymerization can be started by removing oxygen in the reaction system by nitrogen substitution and adding a radical polymerizable initiator to produce a polymer. In addition, the presence of a chain transfer agent, a crosslinking agent or the like before the start of polymerization is the same as other polymerization methods.



General formula (1)
R1 is hydrogen or a methyl group, R2 and R3 are alkyl or alkoxyl groups having 1 to 3 carbon atoms, R4 is hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group or a benzyl group, which may be the same or different. Represents oxygen or NH, B represents an alkylene group or alkoxylene group having 2 to 4 carbon atoms, and X1 represents an anion.
General formula (2)
R5 represents hydrogen or a methyl group, R6 and R7 each represents an alkyl group having 1 to 3 carbon atoms, an alkoxy group or a benzyl group, and X2 represents an anion.

The polymer dispersant can be either a cationic or nonionic polymer, but a cationic polymer is more preferable. Examples of the cationic polymer include polymers such as (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, and dimethyldiallylammonium chloride, which are cationic monomers. A copolymer of the cationic monomer and the nonionic monomer can also be used. Examples of nonionic monomers include acrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, acrylonitrile, diacetone acrylamide, 2-hydroxyethyl (meth) acrylate And N-acryloylmorpholine. Examples of other ionic polymer polymers include cation-modified polyvinyl alcohol, polyvinylamine, polyvinylamidine, polyethyleneimine, polyethyleneimine-modified products, butene / maleic anhydride cation-modified products, and the like.

Examples of nonionic polymers include polymers of the above nonionic monomers, polyvinyl alcohol, butene / maleic anhydride, and fully amidated products of styrene / maleic anhydride. The molecular weight of the ionic polymer is 10,000 to 3,000,000, preferably 50,000 to 1,000,000. The molecular weight of the nonionic polymer is 10,000 to 500,000, preferably 10,000 to 100,000.

The amount of the polymer dispersant added to the monomer is 1/100 to 15/100, preferably 3/100 to 15/100, based on the monomer.

Examples of the monomer represented by the general formula (1) among the cationic monomers used for polymerizing the water-soluble polymer include (meth) Examples thereof include dimethylaminoethyl acrylate and dimethylaminopropyl (meth) acrylamide. Examples of the quaternary ammonium group-containing monomer include (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyl, which is a quaternized product of the tertiary amino-containing monomer with methyl chloride or benzyl chloride. Oxy-2-hydroxypropyltrimethylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloyloxy 2-hydroxypropyldimethylbenzylammonium chloride, (meta ) Acrylylaminopropyldimethylbenzylammonium chloride and the like. Examples of the cationic monomer represented by the general formula (2) include dimethyldiallylammonium chloride or diallylmethylbenzylammonium chloride.

Nonionic monomers other than (meth) acrylamide include N, N-dimethylacrylamide, vinyl acetate, acrylonitrile, methyl acrylate, 2-hydroxyethyl (meth) acrylate, diacetone acrylamide, N- Examples include vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, acryloylmorpholine and the like.

In the present invention, an amphoteric water-soluble polymer can also be used. In this case, the anionic monomer to be used may be a sulfonic acid group or a carboxyl group, and both may be used in combination. Examples of the sulfonic acid group-containing monomer include vinyl sulfonic acid, vinyl benzene sulfonic acid, and 2-acrylamido 2-methylpropane sulfonic acid. Examples of the carboxyl group-containing monomer include methacrylic acid, acrylic acid, itaconic acid, maleic acid, and p-carboxystyrene.

The molar ratio of the cationic monomer when producing the dispersion of the cationic water-soluble polymer is 10 to 70 mol%, preferably 20 to 50 mol%. When the amphoteric water-soluble polymer dispersion is produced, the amount of the cationic monomer is 10 to 70 mol%, preferably 20 to 70 mol%. Moreover, 5-50 mol% is preferable and, as for an anionic monomer, More preferably, it is 5-40 mol%. Acrylamide is 20 to 85 mol%, preferably 45 to 85 mol%.

Also, polyfunctional monomers such as N, N-methylenebisacrylamide and ethylene glycol (meth) acrylate, or N, N-dimethyl (meth) acrylamide and N, N-diethyl (meth) acrylamide It is also possible to synthesize and modify a crosslinked or branched polymer by copolymerizing a thermally crosslinkable monomer.

The polymerization conditions are usually appropriately determined according to the monomer used and the copolymerization mol%, and the temperature is in the range of 0 to 100 ° C. For the initiation of polymerization, a radical polymerization initiator is used. These initiators may be either oil-soluble or water-soluble, and can be polymerized by any of azo, peroxide, and redox systems. Examples of oil-soluble azo initiators are 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexanecarbonitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2-methylpropionate), 4,4-azobis (4-methoxy-2,4dimethyl) valeronitrile and the like are mentioned and dissolved in a water-miscible solvent and added.

Examples of water-soluble azo initiators include 2,2′-azobis (amidinopropane) dichloride, 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] And dihydrochloride, 4,4′-azobis (4-cyanovaleric acid), and the like. Examples of redox systems include a combination of ammonium peroxodisulfate and sodium sulfite, sodium hydrogen sulfite, trimethylamine, tetramethylethylenediamine, and the like. Further examples of peroxides include ammonium or potassium peroxodisulfate, hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, succinic peroxide, t-butylperoxy 2-ethylhexanoate, and the like. I can give you. Most preferred among these initiators are 2,2′-azobis (amidinopropane) dihydrochloride, 2,2′-azobis [2- (5-methyl-2-imidazoline), which is a water-soluble azo initiator. -2-yl) propane] dihydrochloride.

As salts to be used, salts of alkali metal ions such as sodium and potassium, ammonium ions and halide ions, sulfate ions, nitrate ions, phosphate ions, etc. can be used, but salts with polyvalent anions. Is more preferable. The salt concentration of these salts can be used from 10% by weight to a saturated concentration.

(Examples) Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

(Synthesis Example 1 of dispersion in salt aqueous solution) In a five-necked separable flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen introduction tube, a polymer of acryloyloxyethyltrimethylammonium chloride (20% aqueous solution, Molecular weight 2 million), 43.8 g (7.0% monomer), ion-exchanged water 155.0 g, ammonium sulfate 115.0 g, acrylamide 50% aqueous solution 67.4 g and acryloyloxyethyltrimethylammonium chloride, 80% aqueous solution 115.0 g was charged and completely dissolved. After maintaining the internal temperature at 33 to 35 ° C. and replacing with nitrogen for 30 minutes, 1% of 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride as an initiator 1.9 g of an aqueous solution (0.015% monomer) was added to initiate polymerization. After 2.5 hours from the start, a slight increase in viscosity of the reaction product was observed, but the state continued for 30 minutes, but then it settled and transferred to the dispersion. After 8 hours from the start, 0.9 g of the initiator solution was added and polymerization was further performed for 8 hours. The resulting dispersion had a squeeze monomer concentration of 25.0%, a polymer particle size of 10 μm or less, and a viscosity of the dispersion of 370 mPa · s. Moreover, the weight average molecular weight was measured with the molecular weight measuring device (DLS-7000 by Otsuka Electronics) by a static light scattering method. This sample is designated as prototype-1. The results are shown in Table 1.

(Synthesis Example 2) Trial production-2 to trial production-4 were synthesized with the monomer composition shown in Table 1 by the same operation as in Synthesis Example 1. The results are shown in Table 1.
(Table 1)
DMQ; acryloyloxyethyltrimethylammonium chloride DMC; methacryloyloxyethyltrimethylammonium chloride DMBC; acryloyloxyethylbenzyldimethylammonium chloride AAC; acrylic acid, AAM: acrylamide, dispersion viscosity; mPa · s,

As a water-soluble polymer solution, Sample-1 to Sample-4 in Table 1 were dissolved in 0.3% by mass as a water-soluble polymer concentration and further diluted to 0.1% by mass. . In addition, as a papermaking raw material, DIP: LBKP for medium-size paper production was prepared to be 60:40, calcium carbonate (TP-121 manufactured by Okutama Kogyo Co., Ltd.) was added 2.4% (vs. SS), from the papermaking site Diluted with collected white water, it has physical properties of pH 7.53, SS 0.6620%, ash content 0.1618%, cation requirement 0.0146 meq / L, fine fiber content 24.3% (125P; equivalent to 200 mesh) Papermaking raw materials were prepared. Add 500mL of papermaking raw material to a Brit type dynamic gate tester, add 0.1ppm water-soluble polymer to solid content of 150ppm of paper stock, start stirring at 1200rpm, and after stirring for 30 seconds, discharge white water for 10 seconds. Collect white water for 30 seconds. The total yield rate (SS concentration) was measured using ADVANTEC NO. It filtered and measured by 2. A 125P screen (corresponding to 200 mesh) was used as the wire. After drying, the filter paper was incinerated at 525 ° C., the ash content was measured, and the yield was calculated. The measurement results are shown in Table 2.

(Comparative Test 1) Samples 1 to 4 in Table 1 were directly dissolved in 0.1% by mass as water-soluble polymer concentrations by the same test operation as in Example 1. The measurement results are shown in Table 2.

(Table 2)
Amount added; raw material to paper (%), T-OPR; total one-pass retention (yield on wire (% by weight), F-OPR; filler one-pass retention (yield on wire (% by weight) liquid viscosity; mPa · s (25 ° C)

As a water-soluble polymer solution, Sample-1 to Sample-4 in Table 1 were dissolved in 0.3% by mass as a water-soluble polymer concentration and further diluted to 0.1% by mass. . Moreover, as a papermaking raw material, a sample for producing high-quality paper was used, diluted with white water collected from the papermaking site, pH 7.59, SS 0.8364%, ash content 0.1739%, cation requirement 0.0074 meq / L, fine fiber content A papermaking raw material having physical properties of 15.1% (125P; equivalent to 200 mesh) was prepared. Add 500mL of papermaking raw material to a Brit type dynamic gate tester, add 0.1ppm water-soluble polymer to solid content of 150ppm of paper stock, start stirring at 1200rpm, and after stirring for 30 seconds, discharge white water for 10 seconds. Collect white water for 30 seconds. The total yield rate (SS concentration) was measured using ADVANTEC NO. It filtered and measured by 2. A 125P screen (corresponding to 200 mesh) was used as the wire. After drying, the filter paper was incinerated at 525 ° C., the ash content was measured, and the yield was calculated. Table 3 shows the measurement results.

(Comparative Test 2) Samples 1 to 4 in Table 1 were directly dissolved in 0.1% by mass as a water-soluble polymer concentration by the same test operation as in Example 2. Table 3 shows the measurement results.

(Table 3)
Amount added; raw material to paper (%), T-OPR; total one-pass retention (yield on wire (% by weight), F-OPR; filler one-pass retention (yield on wire (% by weight) liquid viscosity; mPa · s (25 ° C)

As a water-soluble polymer solution, Sample-1 to Sample-4 in Table 1 were dissolved in 0.3% by mass as a water-soluble polymer concentration and further diluted to 0.1% by mass. . Further, neutral newspaper papermaking is used as a papermaking raw material, calcium carbonate (TP-121 manufactured by Okutama Kogyo Co., Ltd.) is added, diluted with fresh water, pH 7.54, SS 0.8724%, ash content 0.5313%, cation requirement amount 0. A papermaking raw material having physical properties of 0104 meq / L and a fine fiber content of 18.3% (125 P; equivalent to 200 mesh) was prepared. 500 mL of papermaking raw material is put into a Brit type dynamic gate tester, 0.1 mass% water-soluble polymer is added at 200 ppm solids to the paper stock, stirring is started at 1200 rpm, white water is discharged for 10 seconds after stirring for 30 seconds. Collect white water for 30 seconds. The total yield rate (SS concentration) was measured using ADVANTEC NO. It filtered and measured by 2. A 125P screen (corresponding to 200 mesh) was used as the wire. After drying, the filter paper was incinerated at 525 ° C., the ash content was measured, and the yield was calculated. Table 4 shows the measurement results.

(Comparative Test 3) Samples 1 to 4 in Table 1 were directly dissolved in 0.1% by mass as a water-soluble polymer concentration by the same test operation as in Example 3. Table 4 shows the measurement results.

(Table 4)
Amount added; raw material to paper (%), T-OPR; total one-pass retention (yield on wire (% by weight), F-OPR; filler one-pass retention (yield on wire (% by weight) liquid viscosity; mPa · s (25 ° C)

Claims (4)

In a papermaking raw material before papermaking, a monomer containing a cationic monomer represented by the following general formula (1) and / or (2) and (meth) acrylamide as essential components is dissolved in an aqueous salt solution. In dissolving a dispersion composed of water-soluble polymer fine particles obtained by dispersion polymerization in an aqueous salt solution in the presence of a molecular dispersant, the water-soluble polymer concentration is dissolved in the range of 0.2 to 1.0% by mass. And then making a paper by adding a diluted solution mixed with dilution water to make paper.
General formula (1)
R1 is hydrogen or a methyl group, R2 and R3 are alkyl or alkoxyl groups having 1 to 3 carbon atoms, R4 is hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group or a benzyl group, which may be the same or different. Represents oxygen or NH, B represents an alkylene group or alkoxylene group having 2 to 4 carbon atoms, and X1 represents an anion.
General formula (2)
R5 represents hydrogen or a methyl group, R6 and R7 each represent an alkyl group having 1 to 3 carbon atoms, an alkoxy group or a benzyl group, and X2 represents an anion. The papermaking method according to claim 1, wherein the water-soluble polymer has a weight average molecular weight of 10 million or more. The papermaking method according to claim 1 or 2, wherein the water-soluble polymer concentration of the solution obtained by mixing and diluting the dilution water is 0.05 to 0.15% by mass. The papermaking method according to claim 1, wherein the content of fine fibers in the papermaking raw material before papermaking is 10 to 40% by mass.