JP2006182816A - Crosslinked water-soluble polymer dispersion liquid and paper making method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently producing a crosslinked water-soluble polymer in a state of stable dispersion liquid to improve the aggregation function of a cationic or amphoteric water-soluble polymer by the dispersion polymerization in an aqueous solution of a salt in the presence of a polymer dispersing agent soluble in the salt solution and to develop a paper making method to use the crosslinked water-soluble polymer. <P>SOLUTION: The crosslinked water-soluble polymer having a turbidity of 5-200 FAU (measured by visible light of 850 nm wavelength) measured by diluting the polymer with water to a polymer concentration of 0.5 wt.% and determining with a spectrophotometer is produced in high efficiency in a stably dispersed liquid state by a dispersion polymerization of a water-soluble monomer (mixture) composed of a cationic water-soluble monomer and optionally an anionic monomer, (meth)acrylamide and other copolymerizable nonionic water-soluble monomer in an aqueous solution of a salt in the presence of a polymer dispersing agent soluble in the salt solution. The addition of the crosslinked water-soluble polymer dispersion liquid to a paper-making raw materials before the paper making process improves the yield and/or freeness and gives a paper sheet having good formation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a crosslinked water-soluble polymer dispersion and a papermaking method using the same. Specifically, the turbidity of a solution diluted with water to a polymer concentration of 0.5% by weight is measured with a spectrophotometer. 5 to 200 FAU (measured by visible light having a wavelength of 850 nm), a cationic water-soluble monomer in a salt aqueous solution in the presence of a polymer dispersant soluble in the salt aqueous solution And, if necessary, a water-soluble monomer (mixture) composed of an anionic monomer, (meth) acrylamide and other nonionic water-soluble monomer copolymerizable in the presence of a crosslinking agent. A water-soluble polymer dispersion which is a dispersion of fine particles having a particle diameter of 100 μm or less produced by the above process, and a papermaking raw material before papermaking for the purpose of improving the yield and / or drainage In the cross-linked water-soluble polymer Relates liquid or to the paper making method of adding the diluent.

Cationic or amphoteric water-soluble polymers have been applied to a wide variety of uses as flocculants. For example, it is used for solid-liquid separation in wastewater as a general water treatment agent, sludge dewatering, a yield improver in the paper industry, and as a soil solidifying agent in civil engineering.

The following are known methods for polymerizing these cationic or amphoteric water-soluble polymers. For example, the aqueous solution polymerization method is supplied as a pasty product, and the water-in-oil emulsion polymer dispersion is supplied in the form of a latex after adding a hydrophilic emulsifier called a phase inversion agent after polymerization. In many cases, the dispersion polymerization method is applied to produce a powdered product. A monomer aqueous solution with a concentration of 30 to 50% is polymerized as it is, and the gel polymer is directly granulated with a meat chopper or the like. The drying method is also applied to the production of powder products. A method of polymerizing in an aqueous salt solution has also been developed.

A water-soluble polymer dispersion prepared by a dispersion polymerization method in which a water-soluble monomer or a water-soluble monomer mixture is coexisted with an ionic polymer dispersant soluble in the aqueous salt solution is disclosed in Patent Literature 1 and the polymerization method described in Patent Document 2.

Further, in recent years, as a method for further improving the conventional performance, a crosslinked cationic or amphoteric water-soluble polymer of a water-in-oil emulsion polymer dispersion is used as a water treatment dehydrating agent, a yield improving agent in papermaking process, a drainage improving agent. Examples of effective performance have been reported. This dispersion is a dispersion obtained by polymerization by mixing a crosslinking agent in a cationic and optionally an anionic water-soluble monomer (mixture). A method for polymerizing the water-soluble monomer in the presence of a crosslinking agent by a dispersion polymerization method in an aqueous salt solution has not yet been studied.

Japanese Patent Publication No. 4-39481 Japanese Patent Publication No. 6-51755

The present inventors paid attention to a crosslinked cationic or amphoteric water-soluble polymer in order to further upgrade the function of the cationic or amphoteric water-soluble polymer as a flocculant. Accordingly, an object of the present invention is to provide a stable dispersion state when a crosslinked cationic or amphoteric water-soluble polymer is produced in a salt aqueous solution by a dispersion polymerization method in the presence of a polymer dispersant soluble in the salt aqueous solution. And a papermaking method using the cross-linked cationic or amphoteric water-soluble polymer dispersion or a diluted solution thereof.

一般式（１）
Ｒ１は水素又はメチル基、Ｒ２、Ｒ３は炭素数１〜３のアルキルあるいはアルコキシル基、Ｒ４は水素、炭素数１〜３のアルキル基、アルコキシル基あるいはベンジル基であり、同種でも異種でも良い、Ａは酸素又はＮＨ、Ｂは炭素数２〜４のアルキレン基又はアルコキシレン基、Ｘ１は陰イオンをそれぞれ表わす。

一般式（２）
Ｒ５は水素又はメチル基、Ｒ６、Ｒ７は炭素数１〜３のアルキル基、アルコキシ基あるいはベンジル基、Ｘ２は陰イオンをそれぞれ表わす。

一般式（３）
Ｒ８は水素、メチル基又はカルボキシメチル基、ＡはＳＯ３、Ｃ６Ｈ４ＳＯ３、ＣＯＮＨＣ（ＣＨ３）２ＣＨ２ＳＯ３、Ｃ６Ｈ４ＣＯＯあるいはＣＯＯ、Ｒ９は水素又はＣＯＯＹ２、Ｙ１あるいはＹ２は水素又は陽イオンを表わす。 As a result of detailed studies to solve the above problems, it has been found that a high molecular weight crosslinked cationic or amphoteric water-soluble polymer can be produced by advancing the reaction under specific polymerization conditions. That is, the invention of claim 1 is a crosslinked type in which the turbidity of a solution diluted with water to a polymer concentration of 0.5% by weight is 5 to 200 FAU (measured with visible light having a wavelength of 850 nm) as measured with a spectrophotometer. A water-soluble polymer, wherein the cross-linked water-soluble polymer is represented by 5 to 100 mol% of a monomer represented by the following general formula (1) and / or (2), and represented by the following general formula (3). A monomer (mixture) consisting of 0 to 50 mol% of monomer, 0 to 95 mol% of (meth) acrylamide and other nonionic water-soluble monomer copolymerizable in the presence of a crosslinking agent A cross-linked water-soluble polymer dispersion characterized by being a dispersion of fine particles having a particle size of 100 μm or less produced by a dispersion polymerization method in which a polymer dispersant soluble in the aqueous salt solution coexists in an aqueous solution.

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.

General formula (3)
R8 represents hydrogen, methyl group or carboxymethyl group, A represents SO3, C6H4SO3, CONHC (CH3) 2CH2SO3, C6H4COO or COO, R9 represents hydrogen or COOY2, Y1 or Y2 represents hydrogen or a cation.

The invention according to claim 2 is the crosslinked water-soluble polymer dispersion according to claim 1, wherein the crosslinked water-soluble polymer is cationic.

The invention according to claim 3 is the crosslinked water-soluble polymer dispersion according to claim 1, wherein the crosslinked water-soluble polymer is amphoteric.

The invention according to claim 4 is the crosslinked water-soluble polymer dispersion according to any one of claims 1 to 3, wherein the crosslinking agent is a water-soluble polyvinyl compound.

The invention according to claim 5 is the crosslinked water-soluble polymer dispersion according to any one of claims 1 to 3, wherein the polymer dispersant is cationic.

The invention according to claim 6 is characterized in that the intrinsic viscosity measured in a 1 N NaCl aqueous solution of the crosslinkable water-soluble polymer constituting the crosslinkable water-soluble polymer dispersion is 6 to 20 dl / g. The crosslinked water-soluble polymer dispersion according to any one of claims 1 to 5.

The invention according to claim 7 is the cross-linked water-soluble polymer dispersion according to any one of claims 1 to 6, wherein the salt constituting the aqueous salt solution contains at least one kind of polyvalent anion salt. It is.

The invention according to claim 8 is the cross-linked water-soluble polymer dispersion according to any one of claims 1 to 7 in the papermaking raw material before papermaking for the purpose of improving the yield and / or drainage. The paper making method is characterized by adding the diluted solution.

Crosslinked cationic or amphoteric water-soluble polymer in which the turbidity of a solution diluted with water to a polymer concentration of 0.5% by weight is 5 to 200 FAU (measured with visible light having a wavelength of 850 nm) as measured with a spectrophotometer A water-soluble monomer (mixture) comprising a cationic water-soluble monomer and optionally an anionic monomer and (meth) acrylamide and other nonionic monomers copolymerizable ) In the presence of a cross-linking agent in the presence of a salt solution and in the presence of a polymer dispersant that is soluble in the salt solution, by a dispersion polymerization method, a stable dispersion composed of fine particles having a particle size of 100 μm or less is efficiently produced. Can be manufactured.

Since the crosslinked cationic or amphoteric water-soluble polymer of the present invention is a precipitation polymerization in an aqueous salt solution in the presence of a small amount of a crosslinking agent, the polymer concentration at the time of precipitation becomes very high. As a result, the molecule is likely to be crystallized, tends to be highly concentrated locally, and is considered to promote crystallization. Therefore, it is presumed that a part of the polymer is a molecule contracted in the solution by crystallization or covalent bonding by a crosslinking agent. When a polymer in such a state is used as a yield improver in the paper industry, the papermaking raw material flocs do not become enormous and are tightened small and strong in market share. Accordingly, not only the yield is improved, but also paper having a good texture can be produced.

The production method will be specifically described below. Cationic monomer used as a raw material, that is, general formula (1) and / or (2), anionic monomer as required, that is, general formula (3), (meth) acrylamide and other copolymerizable An aqueous solution comprising a nonionic water-soluble monomer and a crosslinking agent are each dissolved in an aqueous salt solution. Thereafter, the polymer dispersant is added, and after substitution with nitrogen, polymerization is started with a radical polymerization initiator, and polymerization is performed while stirring.

Although the temperature at the time of superposition | polymerization changes with kinds of initiator, generally it is 5-55 degreeC. Polymerization is performed using 2,2-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, or 4,4-azobis (4-methoxy-2,4dimethyl) valeronitrile. Azo initiators are preferred. The initiator is added in an amount of 50 to 500 ppm, preferably 70 to 200 ppm per monomer at the start of polymerization. However, since the polymerization rate is lowered by a single addition, it is preferable to add in several portions.

In addition, when copolymerizing with a redox initiator, it is difficult to control the polymerization if the polymerization is started at a temperature of 40 ° C. or higher, and a rapid increase in temperature or agglomeration of the polymerization solution occurs, resulting in a stable dispersion at a high polymerization degree. Since a liquid is not obtained, 15-35 degreeC is preferable. The initiator is added in an amount of 5 to 100 ppm, preferably 10 to 50 ppm per monomer at the start of polymerization. However, since the polymerization rate is lowered by a single addition, it is preferably added several times. As addition frequency, it is 2-5 times, Preferably it is 2-3 times.

In the case of polymerizing the crosslinked cationic water-soluble polymer, examples of the cationic monomer used include dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, and methyldiallylamine. 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 ) Acryloylaminopropyldimethylbenzylammonium chloride, dimethyldiallylammonium chloride and the like.

In the case of polymerizing the cross-linked amphoteric water-soluble polymer, in addition to the cationic monomer, an anionic monomer is used in combination, for example, vinyl sulfonic acid, vinyl benzene sulfonic acid or 2-acrylamido 2-methylpropane. Examples thereof include sulfonic acid, methacrylic acid, acrylic acid, itaconic acid, maleic acid, and p-carboxystyrene. Furthermore, the water-soluble polymer of the present invention may be a copolymer with another nonionic monomer. For example, (meth) acrylamide, N, N-dimethylacrylamide, vinyl acetate, acrylonitrile, methyl acrylate, 2-hydroxyethyl (meth) acrylate, diacetone acrylamide, N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide The copolymerization with these 1 type (s) or 2 or more types is possible.

The composition of the monomer to be polymerized (mixture) is 5 to 100 mol% of the monomer represented by the general formula (1) and / or (2), and the monomer 0 to 0 represented by the general formula (3). Monomers (mixtures) comprising 50 mol%, (meth) acrylamide and 0 to 95 mol% of other copolymerizable nonionic water-soluble monomers are preferred.

The cross-linking agents used are water-soluble polyvinyl compounds N, N-methylenebis (meth) acrylamide, triallylamine, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, di Examples include methacrylic acid-1,3-butylene glycol, polyethylene glycol di (meth) acrylate, N-vinyl (meth) acrylamide and the like. As other polyvinyl compounds, N-methylallylacrylamide, glycidyl acrylate, polyethylene glycol diglycidyl ether, and the like can be used. Acrolein, glyoxal, vinyltrimethoxysilane and the like that can react with the side chain in the polymer can also be used. Of these crosslinking agents, water-soluble polyvinyl compounds are more preferred, and most preferred is N, N-methylenebis (meth) acrylamide. The amount of the crosslinking agent added is 0.1 to 100 ppm, preferably 0.5 to 20 ppm per monomer. If it exceeds 100 ppm, the molecules will shrink too much and good performance cannot be obtained. Further, a chain transfer agent such as sodium formate and isopropyl alcohol can be used in combination.

The polymer dispersant used in the present invention can be used either ionic or nonionic, but is preferably ionic, and more preferably cationic. In the case of a cationic polymer dispersant, a (co) polymer of a cationic monomer such as (meth) acryloyloxyethyltrimethylammonium chloride or dimethyldiallylammonium chloride is used as the polymer dispersant. Copolymers of monomers and nonionic monomers 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 A copolymer with acrylamide is preferred.

Nonionic polymer dispersants include polyvinylpyrrolidone, acrylamide / polyvinylcaprolactam copolymer, acrylamide / styrene copolymer, and complete amidation product of maleic anhydride / butene copolymer, and some hydrophobicity A water-soluble polymer having a group is also effective.

The molecular weight of these cationic polymer dispersants is 5,000 to 2,000,000, preferably 50,000 to 1,000,000. The molecular weight of the nonionic polymer dispersant is 1,000 to 100,000, preferably 1,000 to 50,000. The addition amount of these nonionic or ionic polymer dispersants is 1 to 20% by weight, preferably 5 to 15% by weight, based on the monomer.

As the salt to be used, a combination of a cation such as an alkali metal ion such as sodium or potassium or an ammonium ion and an anion such as halide ion, sulfate ion, nitrate ion or phosphate ion can be used. However, a salt with a polyvalent anion is more preferable. The salt concentration of these salts can be used from 10% by weight to a saturated concentration.

The crosslinked water-soluble polymer of the present invention has a turbidity of a solution diluted with water to a polymer concentration of 0.5% by weight, as measured with a spectrophotometer, preferably 5 to 200 FAU, preferably 10 to 100 FAU (with a wavelength of 850 nm). Measured by visible light). This turbidity varies depending on the amount and molecular weight of the cross-linking agent to be added, but if the turbidity is lower than 5 FAU, the degree of shrinkage of the molecule in the dilute solution is low, so the characteristic performance of the cross-linked water-soluble polymer is not exhibited. . On the other hand, if the turbidity is higher than 200 FAU, the degree of molecular shrinkage in the diluent is too high. That is, the particles are insolubilized in water and the performance such as the yield effect in the paper industry is lowered. Therefore, it needs to have moderate turbidity.

When the crosslinked water-soluble polymer of the present invention is diluted with water, weak white turbidity is observed. The details of this cause are still unknown, but are estimated as follows. That is, the present invention is precipitation polymerization in an aqueous salt solution. Therefore, the polymer concentration becomes very high when insolubilized in the salt solution. As a result, the molecules are placed in a state where they are easily crystallized. In addition to this state, a small amount of a crosslinking agent coexists to carry out the polymerization, so that the concentration tends to be high locally, and it is considered that crystallization is promoted. Therefore, it is presumed that a part of the polymer is a molecule contracted in the solution by crystallization or covalent bonding by a crosslinking agent. The cross-linking reaction itself is not a direct factor for crystallization, but is considered to be one factor for promoting crystallization. This cloudiness does not cause precipitation or two-layer separation even when the diluted solution is stored for a certain period of time, exists in a stable state, and exhibits the properties of the crosslinked water-soluble polymer of the present invention. It seems to be a thing.

The degree of white turbidity of the crosslinked water-soluble polymer produced by dispersion polymerization in an aqueous salt solution in the presence of the crosslinking agent of the present invention also varies depending on the molecular weight. That is, even if the amount of the crosslinking agent present during polymerization is small, the degree of white turbidity increases as the molecular weight of the polymer produced increases. Conversely, it was found that even if the amount of the crosslinking agent present during polymerization is high, the degree of cloudiness tends to be low if the molecular weight of the polymer is low. Although details of this phenomenon are unknown, the polymer constituting the dispersion in the salt aqueous solution of the present invention can be a preferable yield improver in the paper industry when a water-soluble polymer having a high molecular weight is produced in the presence of a crosslinking agent. I understood. The intrinsic viscosity of this polymer measured in a 1N NaCl aqueous solution is 6 to 20 dl / g, more preferably 10 to 20 dl / g.

The degree of white turbidity is measured with a spectrophotometer such as DR / 4000 manufactured by HACH using visible light of 850 nm. In the present invention, it is defined by the turbidity of a solution diluted with water to a polymer concentration of 0.5% by weight.

Since the crosslinked water-soluble polymer of the present invention is a precipitation polymerization in an aqueous salt solution in the presence of a small amount of a crosslinking agent, the polymer concentration at the time of precipitation is very high. As a result, the molecule is likely to be crystallized, tends to be highly concentrated locally, and is considered to promote crystallization. Therefore, it is presumed that a part of the polymer is a molecule contracted in the solution by crystallization or covalent bonding by a crosslinking agent. When a polymer in such a state is used as a yield improver in the paper industry, the paper-making raw material flocs are not enlarged and tightened to a small size, which is strong in market share. Accordingly, not only the yield is improved, but also paper having a good texture can be produced. Further, it can be used in combination with one or more selected from inorganic flocculants, cationic / anionic and amphoteric water-soluble polymers.

Examples of the inorganic flocculant used in combination include aluminum sulfate, polyaluminum chloride, and polyiron sulfate. Examples of the condensed cationic water-soluble polymer among the cationic polymers include amine / epichlorohydrin condensate. Examples of anionic water-soluble polymers include homopolymers such as (meth) acrylic acid, itaconic acid, maleic acid and acrylamide 2-methylpropanesulfonic acid, or copolymers selected from two or more of the above monomers. Or a copolymer with (meth) acrylamide. An example of the amphoteric water-soluble polymer is a copolymer of a monomer mixture comprising a cationic monomer and an anionic monomer, and optionally a nonionic monomer such as (meth) acrylamide. An example of the cationic water-soluble polymer is a polymer of one or more cationic monomers or a copolymer with a nonionic monomer such as (meth) acrylamide.

Examples of the cationic monomer include dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, and methyl diallylamine. 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 ) Acryloylaminopropyldimethylbenzylammonium chloride, dimethyldiallylammonium chloride and the like.

The molecular weight of the condensed cationic water-soluble polymer, anionic, cationic or amphoteric water-soluble polymer used in combination is several thousand to several hundred thousand in the case of the condensed system, and anionic, cationic or amphoteric. The water-soluble polymer is 1 million to 20 million, preferably 5 million to 15 million.

The addition amount of the crosslinked water-soluble polymer of the present invention is 20 ppm to 5000 ppm, preferably 50 ppm to 1000 ppm, based on the solid content of the papermaking raw material. When used in combination, the amount of the inorganic flocculant added is 0.1 to 5%, preferably 0.5 to 3%. The addition amount of the condensed cationic aqueous polymer is 50 to 2000 ppm, preferably 50 to 500 ppm. The addition amount of the anionic, cationic or amphoteric water-soluble polymer is 20 ppm to 5000 ppm, preferably 50 ppm to 1000 ppm.

When the crosslinkable water-soluble polymer of the present invention is added alone, the fan pump inlet, the screen inlet or the screen outlet where the papermaking raw material is diluted with white water can be considered. As a location for adding the inorganic flocculant or the condensed cationic aqueous polymer used in combination, a machine chest, a fan pump inlet, a screen inlet, or the like can be considered. Further, the addition of the cross-linked water-soluble polymer may be a screen inlet or a screen outlet. In addition, when combining a crosslinkable water-soluble polymer with an anionic, cationic or amphoteric water-soluble polymer, the addition location of the crosslinkable water-soluble polymer is the fan pump inlet or screen inlet, anionic, cationic or The addition site of the amphoteric water-soluble polymer may be the screen entrance or the screen exit.

Examples of paper products to be used for improving the yield and / or drainage of the present invention include high-quality paper, medium-quality paper, newsprint paper, packaging paper, card base paper, liner, core base paper, and white balls.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

In a four-necked 500 ml separable flask equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube, 188.3 g of deionized water, 148.8 g of ammonium sulfate, and 80 wt% acryloyloxyethyltrimethylammonium chloride as a cationic monomer Product (hereinafter DMQ) 17.6 g and 80% by weight acryloyloxyethyldimethylbenzylammonium chloride (hereinafter DMABC) 24.5 g, 50% by weight acrylamide (hereinafter AAM) 82.6 g, 0.01% by weight N, N-methylene A bisacrylamide aqueous solution (0.75 g) and a acryloyloxyethyltrimethylammonium chloride homopolymer (37.5 g) (20% by weight solution, viscosity 6450 mPa · s) were charged as a dispersant. Thereafter, nitrogen was introduced from the nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature was adjusted to 35 ± 2 ° C. using a constant temperature water bath. 30 minutes after nitrogen introduction, 0.75 g of 1% by weight aqueous solution of 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride as an initiator (as a monomer) 100 ppm) was added to initiate the polymerization. The internal temperature was kept at 35 ± 2 ° C., and 6 hours after the start of polymerization, 100 ppm of the above initiator was added to the above monomer, and the reaction was further completed for 10 hours. This obtained dispersion is designated as prototype 1. The DMQ / DMABC / AAM molar ratio was 10/10/80, and the dispersion viscosity was 540 mPa · s. As a result of microscopic observation, the particles were found to be 1 to 50 μm. Furthermore, the turbidity of a solution diluted with water to a polymer concentration of 0.5% by a spectrophotometer (HACH DR / 4000) was found to be 20 FAU. In addition, the intrinsic viscosity in a 1N NaCl aqueous solution was measured using a Canon Fenceke viscometer. The results are shown in Table 1. The solution diluted with water to a polymer concentration of 0.5% by weight was stable with no precipitation or two-layer separation even after storage for one week.

In the same apparatus as in Example 1, 186.7 g of deionized water, 148.8 g of ammonium sulfate, 18.7 g of 80 wt% DMQ as a cationic monomer, and 20.1 g of 80 wt% methacryloyloxyethyltrimethylammonium chloride (hereinafter DMC). , 50 wt% AAM 87.9 g, 0.01 wt% N, N-methylenebisacrylamide aqueous solution 0.38 g, 37.5 g acryloyloxyethyltrimethylammonium chloride homopolymer as a dispersant (20 wt% liquid, viscosity 6450 mPa · Each of s) was charged and reacted in the same manner as in Example 1. The obtained dispersion is referred to as trial production 2. The DMQ / DMC / AAM molar ratio was 10/10/80, and the viscosity of this dispersion was 400 mPa · s. As a result of microscopic observation, the particles were found to be 1 to 50 μm. Further, the turbidity of a solution diluted with water to a polymer concentration of 0.5% by weight was 34 FAU. Similarly, the stability of the diluted solution was checked, and the intrinsic viscosity was measured in a 1N NaCl aqueous solution. The results are shown in Table 1.

In the same manner as in Example 2, 185.5 g of deionized water and 1.5 g of 0.01 wt% N, N-methylenebisacrylamide aqueous solution were added and reacted in the same manner as in Example 2. The resulting dispersion is referred to as prototype 3. The viscosity of this dispersion was 370 mPa · s. As a result of microscopic observation, the particles were found to be 1 to 50 μm. Further, the turbidity of a solution diluted with water to a polymer concentration of 0.5% by weight was 64 FAU. Similarly, the stability of the diluted solution was checked, and the intrinsic viscosity was measured in a 1N NaCl aqueous solution. The results are shown in Table 1.

In the same apparatus as in Example 1, 194.0 g of deionized water, 148.8 g of ammonium sulfate, 80% by weight DMQ 33.2 g and 80% by weight DMC 17.8 g, 50% by weight AAM 68.3 g, 0.01% As in Example 1, 0.38 g of a weight% N, N-methylenebisacrylamide aqueous solution and 37.5 g of a acryloyloxyethyltrimethylammonium chloride homopolymer (20% by weight liquid, viscosity 6450 mPa · s) were charged as a dispersant. It reacted by the method of. The resulting dispersion is designated as prototype 4. The DMQ / DMC / AAM molar ratio was 20/10/70, and the viscosity of the dispersion was 200 mPa · s. As a result of microscopic observation, the particles were found to be 1 to 50 μm. Further, the turbidity of a solution diluted with water to a polymer concentration of 0.5% by weight was 17 FAU. Similarly, the stability of the diluted solution was checked, and the intrinsic viscosity was measured in a 1N NaCl aqueous solution. The results are shown in Table 1.

In the same apparatus as in Example 1, 188.3 g of deionized water, 148.8 g of ammonium sulfate, 4.6 g of 60 wt% acrylic acid (hereinafter AAC), 80 wt% DMQ 18.7 g and 80 wt% DMC 20 as a cationic monomer. 0.1 g, 50 wt% AAM 82.4 g, 0.01 wt% N, N-methylenebisacrylamide aqueous solution 0.38 g, 37.5 g acryloyloxyethyltrimethylammonium chloride homopolymer as a dispersant (20 wt% liquid, viscosity 6450 mPa · s) was prepared and reacted in the same manner as in Example 1. The resulting dispersion is designated as prototype 5. The molar ratio of AAC / DMQ / DMC / AAM was 5/10/10/75, and the viscosity of the dispersion was 870 mPa · s. As a result of microscopic observation, the particles were found to be 1 to 50 μm. Further, the turbidity of a solution diluted with water to a polymer concentration of 0.5% by weight was 31 FAU. Similarly, the stability of the diluted solution was checked, and the intrinsic viscosity was measured in a 1N NaCl aqueous solution. The results are shown in Table 1.

(Comparative Example 1) In Example 2, polymerization was carried out in the same manner without adding N, N-methylenebisacrylamide. The obtained dispersion is referred to as Comparative 1. The viscosity of this dispersion was 830 mPa · s, and the turbidity of the liquid diluted with water to a polymer concentration of 0.5% by weight was 0 FAU and transparent. Similarly, the intrinsic viscosity was measured in a 1N NaCl aqueous solution. The results are shown in Table 1.

Comparative Example 2 In the same manner as in Example 2, N, N-methylenebisacrylamide to be added was charged as 0.23 g of a 1% by weight aqueous solution and polymerized in the same manner as in Example 2. The obtained dispersion is referred to as Comparative 2. The viscosity of this dispersion was 940 mPa · s, and the turbidity of the liquid diluted with water to a polymer concentration of 0.5% by weight was 323 FAU. Similarly, the intrinsic viscosity was measured in a 1N NaCl aqueous solution. The results are shown in Table 1.

ＤＭＱ：アクリロイルオキシエチルトリメチルアンモニウム塩化物
ＤＭＣ：メタクリロイルオキシエチルトリメチルアンモニウム塩化物
ＡＢＣ：アクリロイルオキシエチルジメチルベンジルアンモニウム塩化物
ＡＡＣ：アクリル酸
ＡＡＭ：アクリルアミド
ＭＢＡ：Ｎ，Ｎ−メチレンビスアクリルアミド（対単量体ｐｐｍ）
数値の単位 分散液粘度：ｍＰａ・ｓ
濁度（重合体濃度０．５重量％）：ＦＡＵ
固有粘度（１規定ＮａＣｌ水溶液中）：ｄｌ／ｇ (Table 1)

DMQ: acryloyloxyethyltrimethylammonium chloride DMC: methacryloyloxyethyltrimethylammonium chloride ABC: acryloyloxyethyldimethylbenzylammonium chloride AAC: acrylic acid AAM: acrylamide MBA: N, N-methylenebisacrylamide (against monomer ppm) )
Unit of numerical value Dispersion viscosity: mPa · s
Turbidity (polymer concentration 0.5% by weight): FAU
Intrinsic viscosity (in 1N NaCl aqueous solution): dl / g

Using papermaking raw materials for producing fine paper (mainly LBKP, pH 6.23, total SS content 2.37% by weight, ash content 0.41% by weight), tap water was added to a pulp concentration of 0.8% by weight. The yield was measured using a diluted, bullet type dynamic jar tester. As additive chemicals, cationic starch vs. papermaking raw material 1.0% by weight, calcium carbonate 50% by weight, neutral rosin size 0.2% by weight, sulfuric acid band 1.0% by weight, cationic and amphoteric water-soluble heavy of the present invention 0.02% by weight of the combined polymer (prototype 1 to prototype 5) or the cationic water-soluble polymer (comparative 1 and 2) polymerized as a comparison is added at intervals of 15 seconds in this order, and stirring is started. After 30 seconds, white water was discharged for 10 seconds, white water was collected for 30 seconds, and the total yield was measured under the following conditions. The stirring condition was a rotation speed of 1000 r. p. m. , Wire 125P screen (equivalent to 200 mesh), total yield (SS concentration) is ADVANTEC NO. It filtered and measured by 2. 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.

(Table 2)

As described above, the crosslinked cationic or amphoteric water-soluble polymer composed of the dispersion in the aqueous salt solution of the present invention has a turbidity of a solution diluted with water to a polymer concentration of 0.5% by weight within an appropriate range. It was found that the yield rate was improved as compared to comparative samples with turbidity less than 5 FAU or samples higher than 200 FAU.

The turbidity of a solution diluted with water of the present invention to a polymer concentration of 0.5% by weight is 5 to 200 FAU (measured by visible light having a wavelength of 850 nm) as measured with a spectrophotometer. In the production of an ionic polymer, the cross-linked water-soluble polymer is a cationic water-soluble monomer and, if necessary, an anionic water-soluble monomer and (meth) acrylamide and other nonionic polymers that can be copolymerized. Fine particles having a particle size of 100 μm or less produced by a dispersion polymerization method in the presence of a crosslinking agent in the presence of a crosslinking agent in the presence of a crosslinking agent in the presence of a polymer dispersant soluble in the aqueous salt solution. Can be efficiently produced in a stable dispersion state. By using this dispersion for solid-liquid separation in wastewater as a general water treatment agent, dewatering of sludge, and in the paper industry, it is used as a yield improver, drainage improver, etc., and a better effect than before is expressed. Industrial value is high.

Claims (8)

A turbidity of a solution diluted with water to a polymer concentration of 0.5% by weight is a cross-linked water-soluble polymer having a turbidity of 5 to 200 FAU (measured by visible light having a wavelength of 850 nm) as measured with a spectrophotometer, The cross-linked water-soluble polymer is a monomer represented by the following general formula (1) and / or (2) 5 to 100 mol%, a monomer represented by the following general formula (3) 0 to 50 mol % (Meth) acrylamide and other copolymerizable nonionic water-soluble monomers (0-95 mol%) in a salt solution in the presence of a crosslinking agent. A cross-linked water-soluble polymer dispersion characterized by being a dispersion of fine particles having a particle diameter of 100 μm or less produced by a dispersion polymerization method in which a soluble polymer dispersant is present together.

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.

General formula (3)
R8 represents hydrogen, a methyl group or a carboxymethyl group, A represents SO3, C6H4SO3, CONHC (CH3) 2CH2SO3, C6H4COO or COO, R9 represents hydrogen or COOY2, Y1 or Y2 represents hydrogen or a cation, respectively. The crosslinked water-soluble polymer dispersion according to claim 1, wherein the crosslinked water-soluble polymer is cationic. The crosslinked water-soluble polymer dispersion according to claim 1, wherein the crosslinked water-soluble polymer is amphoteric. The cross-linking water-soluble polymer dispersion according to claim 1, wherein the cross-linking agent is a water-soluble polyvinyl compound. The cross-linked water-soluble polymer dispersion according to any one of claims 1 to 3, wherein the polymer dispersant is cationic. 6. The intrinsic viscosity measured in a 1N NaCl aqueous solution of the crosslinked water-soluble polymer constituting the crosslinked water-soluble polymer dispersion is 6 to 20 dl / g. A cross-linked water-soluble polymer dispersion according to claim 1. The cross-linked water-soluble polymer dispersion according to any one of claims 1 to 6, wherein the salt constituting the aqueous salt solution contains at least one kind of polyvalent anion salt. Adding the cross-linked water-soluble polymer dispersion according to any one of claims 1 to 7 or a diluting liquid thereof to a papermaking raw material before papermaking for the purpose of improving the yield and / or drainage. Papermaking method characterized by