JP7188113B2 - Surface emulsion sizing agent for papermaking, method for producing surface emulsion sizing agent for papermaking, and coated paper - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface emulsion sizing agent for papermaking, a method for producing a surface emulsion sizing agent for papermaking, and a coated paper.

In general, surface sizing agents for papermaking can be broadly divided into aqueous solutions and emulsion types. has the advantage of relatively low foamability.

However, surface emulsion sizing agents for papermaking are unstable against mechanical shear. There are problems such as foaming, coating unevenness, etc., which lowers the workability, and as a result, the sizing effect is lowered. In particular, this problem becomes conspicuous when hard water such as industrial water in which metal ions are dissolved is used.

As a method for improving the mechanical stability, for example, it is possible to use a high molecular weight compound as a protective colloid together with an anionic or nonionic emulsifier. , a surface sizing agent containing an emulsion obtained by emulsion polymerization of hydrophobic unsaturated monomers such as styrenes has been proposed (Patent Document 1). However, the surface emulsion sizing agent still had insufficient sizing effect and mechanical stability.

JP-A-08-246391

An object of the present invention is to provide a surface emulsion sizing agent for papermaking that exhibits excellent mechanical stability, little foaming, and an excellent sizing effect; a method for producing the surface emulsion sizing agent for papermaking; and a coated paper. .

The inventors of the present invention used rosins to enhance the sizing effect, and assumed that the use of rosins deteriorates mechanical stability. in the shell portion and a polymer of a specific monomer component in the core portion together with rosins to solve the above problems, and completed the present invention. That is, the present invention relates to a surface emulsion sizing agent for papermaking, a method for producing a surface emulsion sizing agent for papermaking, and coated paper as described below.

1. A surface emulsion sizing agent for papermaking having a shell portion containing a surfactant (A) and a core portion containing a polymer (B) of monomer components containing styrenes (b1) and rosins (C).

2. 2. The surface emulsion size for papermaking according to the preceding item 1, wherein the amount of component (A) used is 20 to 200 parts by weight in terms of solid content per 100 parts by weight of the total weight of components (B) and (C). agent.

3. 3. The surface emulsion sizing agent for papermaking according to the preceding item 1 or 2, wherein the component (A) contains a polymer of monomer components containing styrenes (a1) and/or α-olefins (a2), or starches.

4. 4. The surface emulsion sizing agent for papermaking according to any one of the preceding items 1 to 3, wherein the monomer component constituting component (B) further contains a (meth)acrylic acid ester (b2).

5. 5. The surface emulsion sizing agent for papermaking according to any one of the preceding items 1 to 4, wherein the monomer component constituting component (B) further contains an unsaturated monomer (b3) having a hydrophilic group.

6. 6. The papermaking surface according to any one of the preceding items 1 to 5, wherein component (C) contains at least one selected from the group consisting of unmodified rosin, α,β-unsaturated carboxylic acid-modified rosin, and unmodified rosin ester. Emulsion sizing agent.

7. 7. Any one of the preceding items 1 to 6, wherein the use ratio of the component (B) and the component (C) is (B)/(C) = 20/80 to 95/5 in terms of solid weight. A papermaking surface emulsion sizing agent as described.

8. 8. The surface emulsion sizing agent for papermaking according to any one of the preceding items 1 to 7, which has a volume average particle size of 50 to 300 nm.

9. 9. Production of the surface emulsion sizing agent for papermaking according to any one of the preceding items 1 to 8, wherein the monomer component constituting component (B) and component (C) are added dropwise to component (A) and emulsion polymerization is carried out. Method.

10. A coated paper containing the surface emulsion sizing agent for papermaking according to any one of the preceding items 1 to 8.

The surface emulsion sizing agent for papermaking of the present invention exhibits excellent mechanical stability, little foaming, and excellent sizing effect when made into paper.

The surface emulsion sizing agent for papermaking of the present invention (hereinafter also simply referred to as "emulsion sizing agent") comprises a shell portion containing a surfactant (A) (hereinafter referred to as component (A)) and styrenes (b1) ( It has a core portion containing a monomer component polymer (B) (hereinafter referred to as component (B)) containing (hereinafter referred to as component (b1)) and rosins (C) (hereinafter referred to as component (C)). Each component will be described in detail below.

Component (A) is one of the components forming the shell portion of the emulsion sizing agent, and by functioning as a protective colloid, the component (A) is excellent in mechanical stability and has the effect of reducing foaming. Although the type thereof is not particularly limited, in the present invention, for example, monomers containing styrenes (a1) (hereinafter referred to as component (a1)) and/or α-olefins (a2) (hereinafter referred to as component (a2)) From the viewpoint of emulsifiability with the components (B) and (C), the polymer component or starches are preferably used.

Examples of component (a1) include, but are not limited to, styrene, α-methylstyrene, tert-butylstyrene, dimethylstyrene, acetoxystyrene, hydroxystyrene, vinyltoluene, chlorovinyltoluene, and the like. These may be used alone or in combination of two or more.

The amount of component (a1) used is not particularly limited, but from the viewpoint of the size effect of coated paper, it is usually about 20 to 90% by weight when the total of all monomer components constituting component (A) is 100% by weight. It is preferably about 40 to 80% by weight.

Component (a2) is not particularly limited, but examples include diisobutylene (2,4,4-trimethyl-1-pentene, 2,4,4-trimethyl-2-pentene, 2,4,4-trimethyl-1 -pentene and mixtures of 2,4,4-trimethyl-2-pentene), branched α-olefins such as 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene; - Linear α-olefins such as hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 1-tetracosene, and 1-triacontene; cyclohexene, Cyclic α-olefins such as methylcyclohexene, vinylcyclohexane, 4-vinylcyclohexene, cyclopentene, methylcyclopentene and the like are included. These may be used alone or in combination of two or more. Of these, branched α-olefins are preferred, and diisobutylene is more preferred, from the viewpoint of the size effect of coated paper.

The amount of component (a2) used is not particularly limited, but from the viewpoint of the sizing effect of coated paper, it is usually about 0 to 60% by weight when the total of all monomer components constituting component (A) is 100% by weight. It is preferably about 0 to 50% by weight.

In terms of emulsifiability with the (B) component and the (C) component, the monomer component forming the (A) component further includes an unsaturated monomer (a3) having a carboxyl group (hereinafter referred to as the (a3) component), ( A dialkylaminoalkyl meth)acrylate (a4) (hereinafter referred to as component (a4)) and N,N-dialkylaminoalkyl(meth)acrylamide (a5) (hereinafter referred to as component (a5)) are preferably used in combination.

Component (a3) is not particularly limited. , (anhydrous) citraconic acid, or neutralized salts, half esters, neutralized salts of half esters thereof, and the like. These may be used alone or in combination of two or more. Among them, acrylic acid, maleic acid, and maleic anhydride are preferable from the viewpoint of polymerizability with components (a1) and (a2).

The amount of component (a3) used is not particularly limited. About 10 to 80% by weight, preferably about 20 to 50% by weight.

The component (a4) is not particularly limited, but for example, (meth)acrylate-N,N-dimethylaminoethyl, (meth)acrylate-N,N-diethylaminoethyl, (meth)acrylate-N,N -dimethylaminopropyl, (meth)acrylate -N,N-dimethylaminobutyl, (meth)acrylate -N,N-dipropylaminoethyl, (meth)acrylate -N,N-dibutylaminoethyl and the like. be done. These may be used alone or in combination of two or more.

The amount of component (a4) used is not particularly limited, but from the viewpoint of emulsifiability with components (B) and (C), when the total of all monomer components constituting component (A) is 100% by weight, 0 It is about 40% by weight, preferably about 5 to 30% by weight.

Component (a5) is not particularly limited, but examples include N,N-dimethylaminoethyl (meth)acrylamide, N,N-diethylaminoethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, N , N-dimethylaminobutyl (meth)acrylamide, N,N-dipropylaminoethyl (meth)acrylamide, N,N-dibutylaminoethyl (meth)acrylamide and the like. These may be used alone or in combination of two or more.

The amount of component (a5) used is not particularly limited. It is about 0 to 20% by weight, preferably about 1 to 10% by weight.

In the case of using the components (a4) and (a5), it is preferable to quaternize some or all of the amino groups derived from the components (a4) and (a5). It is preferable from the viewpoint of emulsifiability with components. The degree of quaternization is not particularly limited, but is preferably at least about 10 mol%, and about 50 to 100 mol%, of the amino groups of component (a4) and/or component (a5) present in the resulting polymer. is more preferable. Various known quaternizing agents can be used for quaternization, for example, benzyl chloride, methyl chloride, dimethyl sulfate, glycidol, ethylene chlorohydrin, allyl chloride, styrene oxide, propylene oxide, epichlorohydrin, and the like. mentioned. The quaternization is usually carried out at a temperature of about 50 to 90° C. for a time of about 1 to 4 hours, and is usually carried out after preparation of the polymer, but may be carried out before or during the polymerization.

Further, as the monomer component, an unsaturated monomer (a6) (hereinafter referred to as component (a6)) other than components (a1) to (a5) may be used in combination as appropriate. The component (a6) is not particularly limited, and examples thereof include (meth)acrylic acid esters, unsaturated monomers having a sulfonyl group; (meth)acrylamide, and the like.

The (meth)acrylic acid ester is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, Examples include isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate and the like.

The unsaturated monomer having a sulfonyl group is not particularly limited, and examples thereof include vinylsulfonic acid, sodium styrenesulfonate, and sodium (meth)allylsulfonate.

(Meth)acrylamide includes acrylamide and methacrylamide.

These (a6) components may be used alone or in combination of two or more. The amount of component (a6) to be used is not particularly limited, but is preferably about 1 to 10% by weight based on 100% by weight of the total amount of all monomer components forming component (A).

The component (A) of the present invention can be obtained by appropriately combining the above monomer components and polymerizing them in the presence of a polymerization initiator. The polymerization method is not particularly limited, and known methods can be employed. When solution polymerization is employed, aromatic hydrocarbons such as benzene and toluene; ketones such as acetone and methyl ethyl ketone; alcohols such as n-propyl alcohol and isopropyl alcohol, and the like can be used as solvents.

The polymerization initiator is not particularly limited, and examples thereof include azo compounds such as 2,2'-azobisisobutyronitrile and 2,2'-azobis-2,4-dimethylvaleronitrile; benzoyl peroxide; Organic peroxides such as cumene hydroperoxide, tert-butyl hydroperoxide, tert-butyl peroxy-2-ethylhexanoate, dicumyl peroxide, lauryl peroxide; can do. The amount of polymerization initiator to be used is not particularly limited, and is about 0.1 to 5 parts by weight with respect to 100 parts by weight of all the monomer components constituting component (A).

Mercaptans such as 2-mercaptoethanol and n-dodecylmercaptan; alcohols such as ethanol, isopropyl alcohol and pentanol; carbon tetrachloride, ethylbenzene, isopropylbenzene, cumene, α-methylstyrene dimer, 2, Chain transfer agents such as 4-diphenyl-4-methyl-1-pentene can also be used. The amount of the chain transfer agent to be used is not particularly limited, and is about 0.01 to 5 parts by weight with respect to 100 parts by weight of all the monomer components constituting component (A).

As for the conditions for the polymerization reaction, the reaction temperature is usually about 70 to 140° C. and the reaction time is about 1 to 10 hours.

The physical properties of the component (A) obtained by the above method are not particularly limited. It is preferably about 40,000.

As for the polymer, the pH may be adjusted during or after polymerization. For adjustment, various known pH adjusters can be used, for example, inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid; alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; alkaline earth metals such as calcium hydroxide. hydroxides; amines such as monomethylamine, dimethylamine, monoethylamine, diethylamine and triethylamine; and ammonia. Although the pH is not particularly limited, it is preferably adjusted to about 4-10.

The starches are not particularly limited, and examples include unmodified starches such as corn starch, potato starch, tapioca starch, wheat starch, rice starch, and sago starch; cationized starch, oxidized starch, phosphate-modified starch, and carboxymethylated starch. , hydroxyethylated starch, carbamylethylated starch, cyanoethylated starch, dialdehyde starch, modified starch such as acetic acid modified starch; denatured starch modified with a treating agent such as a substance, an enzyme, or an inorganic acid.

The inorganic peroxide is not particularly limited, and examples include hypochlorite; ammonium persulfate (hereinafter also referred to as APS), potassium persulfate (hereinafter also referred to as KPS), sodium persulfate (hereinafter also referred to as SPS ) and other peroxodisulfates; hydrogen peroxide and the like. These may be used alone or in combination of two or more. Furthermore, hydrogen peroxide may be combined with iron sulfate or copper sulfate.

The enzyme is not particularly limited and includes, for example, α-amylases produced by various bacteria, animals and plants.

Inorganic acids are not particularly limited, and examples thereof include hydrochloric acid, sulfuric acid, phosphoric acid and the like. These may be used alone or in combination of two or more.

The amount of the treatment agent to be used is not particularly limited, but from the viewpoint of reactivity with the raw starch, the solid weight is preferably about 0.01 to 10 parts by weight with respect to 100 parts by weight of the raw starch. About 1 to 6 parts by weight is more preferable.

The method for producing modified starch is not particularly limited, and examples thereof include heating an aqueous solution containing starches and a treating agent at a temperature of about 60 to 100° C. for about 30 to 60 minutes.

The physical properties of the modified starch obtained by the production method are not particularly limited. For example, the Brookfield viscosity in an aqueous solution having a solid content concentration of 15% by weight is about 5 to 1000 mPa s at a temperature of 25 ° C., preferably It is about 10 to 200 mPa·s.

The amount of component (A) used is usually 50 to 200 parts by weight in terms of solid weight per 100 parts by weight of components (B) and (C) combined. By setting the value within the above range, the dispersion stability of the emulsion sizing agent and the sizing effect of the coated paper can be enhanced.

As the component (A), cationic surfactants, nonionic surfactants, anionic surfactants and the like can also be used in addition to the above polymers.

The cationic surfactant is not particularly limited, and examples thereof include dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, tetradecyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride and the like. As these commercial products, for example, Cathiogen H and Cathiogen L manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Cortamine 24P, Cortamine 86P Cornk, Cortamine 60W, and Cortamine 86W manufactured by Kao Corporation are available.

Nonionic surfactants are not particularly limited, and examples include polyethylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene styrylphenyl ether, polyoxyethylene sorbitan fatty acid ester, and Examples include nonionic surfactants having reactive functional groups.

The anionic surfactant is not particularly limited, and examples thereof include dialkylsulfosuccinates, alkanesulfonates, α-olefinsulfonates, polyoxyethylene alkyl ether sulfosuccinate salts, and polyoxyethylene styrylphenyl ether sulfosuccinates. Ester salts, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl ether sulfate salts, polyoxyethylene alkylphenyl ether sulfate salts, and the like can be mentioned.

These other surfactants may be used alone or in combination of two or more.

Component (B) contains a polymer of monomer components including component (b1), is one component forming the core of the emulsion sizing agent, and contributes to the sizing effect of coated paper.

The component (b1) is not particularly limited, and includes those exemplified for the component (a1) above. These may be used alone or in combination of two or more.

The amount of component (b1) used is not particularly limited, but from the viewpoint of the size effect of the coated paper, it is usually about 10 to 80% by weight when the total of all monomer components constituting component (B) is 100% by weight. It is preferably about 20 to 70% by weight.

The monomer component that constitutes the component (B) is not particularly limited. , (b3) component) and the like can be used together.

The component (b2) is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, (meth) ) isobutyl acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate and the like. These may be used alone or in combination of two or more. Among them, isobutyl (meth)acrylate is preferable from the viewpoint of the sizing effect of coated paper.

The amount of component (b2) used is not particularly limited, but from the viewpoint of the size effect of coated paper, it is usually about 10 to 80% by weight, with the total of all monomer components constituting component (B) being 100% by weight. It is preferably about 20 to 70% by weight.

Component (b3) is not particularly limited as long as it does not correspond to components (b1) and (b2). Examples include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; itaconic acid; Unsaturated dicarboxylic acids such as itaconic acid, maleic acid, maleic anhydride, fumaric acid, muconic acid, citraconic acid; 2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acrylic acid (Meth)acrylic acid hydroxyalkyl esters such as hydroxy n-propyl and hydroxyisopropyl (meth)acrylate; unsaturated monoalcohols such as allyl alcohol and methallyl alcohol; diethylene glycol (meth)acrylate, triethylene (meth)acrylate polyalkylene glycol-based unsaturated monomers such as glycol, tetraethylene glycol (meth)acrylate, dipropylene glycol (meth)acrylate, tripropylene glycol (meth)acrylate, and tetrapropylene glycol (meth)acrylate; . These may be used alone or in combination of two or more. Among them, acrylic acid is preferred.

The amount of component (b3) used is not particularly limited, but from the viewpoint of the balance between the dispersion stability of the emulsion sizing agent and the sizing effect of the coated paper, the total amount of all monomer components constituting component (B) is 100% by weight. , it is usually about 1 to 20% by weight, preferably about 5 to 20% by weight.

In addition, diethyl maleate, di-n-butyl maleate, isobutyl maleate, as a monomer component (b4) (hereinafter referred to as component (b4)) other than components (b2) and (b3), if necessary , di-n-octyl maleate, di-n-decyl maleate, di-n-dodecyl maleate, di-n-hexadecyl maleate and other unsaturated dicarboxylic acid dialkyl esters; (meth)acrylic acid -N,N-diethylaminoethyl, (meth)acrylic acid -N,N-diethylaminopropyl, (meth)acrylic acid -N,N-diethylaminobutyl (meth)acrylic acid dialkylaminoalkyl esters; vinyl propionate, vinyl esters such as vinyl acetate; acrylonitrile, Nitriles such as methacrylonitrile; N,N-diethyl (meth)acrylamide, N,N-dialkyl (meth)acrylamides such as N,N-dipropyl (meth)acrylamide; N,N'-methylenebis (meth)acrylamide, N , N'-propylene bis(meth)acrylamide, bisacrylamide such as diacrylamide dimethyl ether; vinylsulfonic acid, sodium styrenesulfonate, unsaturated monomers having a sulfonyl group such as sodium (meth)allylsulfonate, etc. good. They may be used alone or in combination of two or more. The amount of component (b4) to be used is not particularly limited, but is preferably about 1 to 20% by weight based on 100% by weight of the total amount of all monomer components forming component (B).

Further, if necessary, mercaptans such as 2-mercaptoethanol and n-dodecylmercaptan; alcohols such as ethanol, isopropyl alcohol and pentanol; carbon tetrachloride, ethylbenzene, isopropylbenzene, cumene, α-methylstyrene dimer; A chain transfer agent such as 4-diphenyl-4-methyl-1-pentene may be used. The amount of the chain transfer agent to be used is about 0.01 to 5 parts by weight per 100 parts by weight of all the monomer components constituting component (B).

Component (C), like component (B), is a core component of the emulsion sizing agent and contributes to the sizing effect of coated paper. In addition, due to the affinity with the component (A), the mechanical stability of the emulsion sizing agent is improved, and contamination of coating equipment and the like can be reduced. Component (C) is not particularly limited, and includes unmodified rosins such as gum rosin, wood rosin, tall oil rosin, Mercury pine rosin (dihydroagatoic acid-containing rosin), wetland pine rosin (comic acid-containing rosin); Rosin, α,β-unsaturated carboxylic acid-modified rosin, disproportionated rosin, or esters thereof (unmodified rosin ester, α,β-unsaturated carboxylic acid-modified rosin ester, disproportionated rosin ester), etc. be done. These may be used alone or in combination of two or more. Among them, from the viewpoint of the sizing effect of coated paper, it preferably contains at least one selected from the group consisting of unmodified rosin, α,β-unsaturated carboxylic acid-modified rosin and unmodified rosin ester, gum rosin, maleated More preferably, it contains at least one selected from rosin and gum rosin esters.

Also, the component (C) may be purified by a known vacuum distillation method, steam distillation method, extraction method, recrystallization method, or the like.

An α,β-unsaturated carboxylic acid-modified rosin is obtained by adding an α,β-unsaturated carboxylic acid to an unmodified rosin. The α,β-unsaturated carboxylic acid is not particularly limited, and examples include α,β-unsaturated dicarboxylic acids such as maleic acid, maleic anhydride and fumaric acid; Saturated monocarboxylic acid and the like can be mentioned. The amount of α,β-unsaturated carboxylic acid to be used is also not particularly limited, and is usually about 1 to 30 parts by weight per 100 parts by weight of unmodified rosin.

The method for producing the α,β-unsaturated carboxylic acid-modified rosin is not particularly limited. A Diels-Alder reaction may be performed at about 190 to 230° C. for about 1 to 3 hours.

The physical properties of the α,β-unsaturated carboxylic acid-modified rosin are not particularly limited, but from the viewpoint of the size effect of coated paper, the softening point is usually about 85 to 140° C. and the acid value is about 195 to 320 mgKOH/g. Preferably, the softening point is about 95-130° C. and the acid value is about 240-295 mgKOH/g.

Unmodified rosin esters are reaction products of unmodified rosin and polyhydric alcohols.

Polyhydric alcohols are not particularly limited, but trihydric alcohols and/or tetrahydric alcohols are preferred, and examples of the former include trimethylolethane, trimethylolpropane and 3-methylpentane-1,3,5-triol. and the latter include pentaerythritol and diglycerin.

Unmodified rosin esters can be produced by various known methods. For example, it can be obtained by subjecting an unmodified rosin and a polyhydric alcohol to an esterification reaction at 200 to 350° C. for 6 to 20 hours. Moreover, the reaction may be carried out under normal pressure, reduced pressure or increased pressure. Also, the ratio of the amount of the unmodified rosin and the polyhydric alcohol used is not particularly limited, but usually the equivalent ratio [OH _(eq) /COOH _(eq) ] of the former carboxyl group and the latter hydroxyl group is 0.2. to about 1.5, preferably about 0.4 to 1.2. Moreover, in the reaction, an esterification catalyst such as p-toluenesulfonic acid or various antioxidants may be used. Alternatively, the reaction may be carried out under a stream of nitrogen.

The physical properties of the unmodified rosin ester are not particularly limited, but from the viewpoint of the size effect of the coated paper, it usually has a softening point of about 80 to 100° C., an acid value of about 0 to 25 mgKOH/g, and a hydroxyl value of 0 to 30 mgKOH/g. Preferably, the softening point is about 85 to 95° C., the acid value is about 10 to 20 mgKOH/g, and the hydroxyl value is about 0 to 10 mgKOH/g.

The use ratio [(B)/(C)] of components (B) and (C) is usually 20/80 to 95/5 in terms of solid weight from the viewpoint of mechanical stability of the emulsion sizing agent. degree, preferably about 50/50 to 90/10.

The surface emulsion sizing agent for papermaking of the present invention can be obtained by various known production methods. The production method is not particularly limited, and for example, component (A), monomer components constituting component (B), and component (C) are charged all at once, and solution polymerization, emulsion polymerization, suspension polymerization is carried out in the presence of a polymerization initiator. In the present invention, from the viewpoint of the polymerizability of the monomer component forming the component (B) and the component (C), in the component (A), the monomer component forming the component (B) and ( A method of emulsion polymerization by dropping component C, more specifically, a method of emulsion polymerization by dropping components (B) and (C) in the presence of component (A) and a polymerization initiator is preferred. In particular, it is preferable to add a mixed solution of the monomer component constituting the component (B) and the component (C) because the resulting emulsion sizing agent is excellent in mechanical stability and sizing effect. The conditions for the emulsion polymerization are not particularly limited, but the temperature is usually about 40 to 150° C. (preferably about 60 to 100° C.), and the time is usually about 1 to 10 hours (preferably about 1 to 3 hours). be.

The polymerization initiator is not particularly limited, and examples thereof include peroxides such as hydrogen peroxide, ammonium persulfate and potassium persulfate; organic peroxides such as mill peroxide and lauryl peroxide; azo compounds such as 2,2'-azobisisobutyronitrile and dimethyl-2,2'-azobisisobutyrate; It may be used alone or in combination of two or more. In addition, the amount of the polymerization initiator used is not particularly limited, and is usually about 0.1 to 10 parts by weight, preferably about 1 to 5 parts by weight, per 100 parts by weight of all the monomer components constituting component (B). is.

In addition, a sulfite such as sodium sulfite, a hydrogen sulfite such as sodium hydrogen sulfite, triethanolamine, cuprous sulfate, or the like may be used in combination with the polymerization initiator.

Moreover, a solvent may be used, if necessary, in the production of the surface emulsion sizing agent for papermaking.

The solvent is not particularly limited, and examples thereof include alcohols such as ethyl alcohol and isopropyl alcohol; ketones such as acetone and methyl ethyl ketone; aromatic hydrocarbons such as toluene and benzene; organic solvents such as ethyl acetate, chloroform and dimethylformamide; Examples include water and a mixed solvent of the above organic solvent and water.

Further, the pH of the surface emulsion sizing agent for papermaking may be adjusted with various known pH adjusters during or after production. The pH adjuster is not particularly limited, and examples thereof include inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid; alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide. amines such as monomethylamine, dimethylamine, monoethylamine, diethylamine and triethylamine; and ammonia.

The physical properties of the surface emulsion sizing agent for papermaking of the present invention are not particularly limited. It is about 80 nm. Such a numerical range provides a balance between the mechanical stability of the emulsion sizing agent and the sizing effect of the coated paper.

Further, the Brookfield viscosity at a solid content concentration of 25% by weight and a temperature of 25° C. is usually about 10 to 200 mPa·s, preferably about 30 to 80 mPa·s.

Also, the pH at a temperature of 25° C. is usually about 7 to 11, preferably about 7.5 to 9.5.

Additives such as antioxidants, antifoaming agents, preservatives, chelating agents, and water-soluble aluminum compounds may be added to the surface emulsion sizing agent for papermaking of the present invention, if necessary.

As a coating liquid containing the surface emulsion sizing agent for papermaking of the present invention, the emulsion sizing agent may be used as it is or diluted with water or the like, and various known additives may be added as necessary. Examples of the additive include starches such as oxidized starch, phosphate esterified starch, self-modified starch, cationized starch and amphoteric starch, celluloses such as carboxymethyl cellulose, polyvinyl alcohols, polyacrylamides, sodium alginate, and the like. Paper strength agents such as water-soluble polymers, anti-slip agents, preservatives, rust inhibitors, pH adjusters, anti-foaming agents, thickeners, fillers, antioxidants, waterproofing agents, film-forming aids , pigments and dyes.

The solid content concentration of the coating liquid is not particularly limited, but it is practically used in the range of about 0.5 to 30% by weight, preferably 1 to 20% by weight.

The invention also relates to coated paper. Coated paper contains a surface emulsion sizing agent for papermaking, and more specifically, is obtained by coating the surface of the base paper with the above-mentioned coating liquid.

The base paper is not particularly limited, and usually uncoated paper and paperboard made from wood cellulose fiber can be used. The base paper is obtained from papermaking pulp, and examples of the papermaking pulp include chemical pulp such as LBKP and NBKP; mechanical pulp such as GP and TMP; and waste paper pulp. In addition, various chemicals such as fillers, internal sizing agents, and paper strength agents may be added to the base paper.

Moreover, the means for applying the coating solution is not particularly limited, and various known methods such as an impregnation method, a size press method, a gate roll method, a bar coater method, a calender method, and a spray method can be applied. The coating amount (concentration) of the coating liquid is also not particularly limited, but is usually about 0.005 to 1 g/m ² , preferably about 0.01 to 0.5 g/m ² .

The coated paper obtained by the above means is not particularly limited, and examples include recording paper such as form paper, PPC paper, and thermal recording paper; coated paper such as art paper, cast coated paper, and high-quality coated paper; Packaging paper such as pure white roll paper; Various types of paper (foreign paper) such as notebook paper, book paper, printing paper, and newsprint paper; be done.

EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these. Parts and percentages in Examples and Comparative Examples are by weight unless otherwise specified.

(viscosity)
Using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.), the viscosity of the sample adjusted to 25° C. was measured.

(pH)
Using a commercially available measuring instrument (product name “pH METER F-14”, manufactured by HORIBA, Ltd.), the pH of a sample (solid content concentration 25%) adjusted to 25° C. was measured.

(softening point)
It was measured by the ring and ball method of JIS K 2531.

(acid number)
Measured according to JIS K 0070.

(hydroxyl value)
Measured according to JIS K 0070.

(Volume average particle size)
It was measured using a light scattering particle size analyzer (product name “ELSZ-2”, manufactured by Otsuka Electronics Co., Ltd.).

Production Example 1-1 (Production of polymer (A-1))
85 parts of isopropyl alcohol, 43 parts of deionized water, 125.9 parts of styrene (70% of all monomer components), 67.5 parts of 80% acrylic acid were placed in a flask equipped with a stirrer, condenser, nitrogen inlet tube and thermometer. (30% of all monomer components) was heated to 70° C. while stirring under a nitrogen stream, and tert-butyl peroxy-2-ethylhexanoate (trade name “Perbutyl O” NOF Corporation ) was charged with 7.3 parts. After further raising the temperature to 80 to 90 ° C. and keeping the temperature for 4 hours to obtain a polymer, then 200 parts of ion-exchanged water, 0.045 part of hydroquinone and 51.0 parts of a 48% potassium hydroxide aqueous solution (in the polymer (equivalent to 50 mol % with respect to the anionic groups of ), neutralized, and then isopropyl alcohol was distilled off. Further, 29.7 parts of 25% aqueous ammonia (equivalent to 50 mol % of the anionic groups in the copolymer) were added and dissolved to obtain a polymer (A-1) having a solid concentration of 25%.

Production Example 1-2 (Production of polymer (A-2))
70.3 parts diisobutylene (2,4,4-trimethyl-1-pentene; purity 76%) (total monomer 53.4% of the components), 46.6 parts of maleic anhydride (46.6% of the total monomer components), and 180 parts of toluene while stirring under a nitrogen stream, the temperature is raised to 70 ° C., and the mixture is tert. 7.3 parts of -butyl peroxy-2-ethylhexanoate (trade name "Per-butyl O", manufactured by NOF Corporation) was charged. After further raising the temperature to 80 to 90 ° C. and keeping it warm for 4 hours to obtain a polymer, then, 200 parts of ion-exchanged water, 0.045 parts of hydroquinone and 35.0 parts of a 48% potassium hydroxide aqueous solution (in the polymer (equivalent to 100 mol % with respect to the anionic groups of ) were charged, neutralized, and then toluene was distilled off to obtain a polymer (A-2) having a solid concentration of 20%.

Production Example 1-3 (Production of polymer (A-3))
70 parts of styrene, 30 parts of dimethylaminoethyl methacrylate, 42.9 parts of isopropyl alcohol, and 2,2'-azobisiso are added to a flask equipped with a stirrer, condenser, dropping funnel, nitrogen inlet and thermometer. 2.5 parts of butyronitrile was charged, and a polymerization reaction was carried out at 80 to 85° C. for 5 hours while stirring under a nitrogen stream. Next, after adding 11.5 parts of acetic acid and 300 parts of water, 17.7 parts of epichlorohydrin was added and the mixture was kept at 80°C for 2 hours. to obtain a polymer (A-3).

Production Example 1-4 (Production of APS-modified starch (A-7))
In a flask equipped with a stirrer, a condenser, a thermometer, and a nitrogen inlet tube, 100 parts of corn starch (trade name: “Oji Ace A”, manufactured by Oji Corn Starch Co., Ltd., solid content concentration 88%), 5 parts of APS , and 300 parts of water were added, the temperature was raised to 90° C., and the mixture was stirred for 1 hour. After that, water was added so that the solid content concentration was 15%, and the mixture was cooled to 40° C. to obtain APS-modified starch (A-7).

Production Example 1-5 (Production of enzyme-modified starch (A-8))
In a flask equipped with a stirrer, condenser, thermometer, and nitrogen inlet tube, 100 parts of corn starch (trade name: "Oji Ace A", manufactured by Oji Corn Starch Co., Ltd., solid content concentration 88%), Crystar 0.1 part of ZeL1 (manufactured by Amano Enzyme Co., Ltd.) and 300 parts of water were added, heated to 75° C., stirred for 40 minutes, then heated to 90° C. and stirred for another 10 minutes. After that, water was added so that the solid content concentration was 15%, and the mixture was cooled to 40° C. to obtain an enzyme-modified starch (A-8).

Production Example 1-6 (Production of sulfate-modified starch (A-9))
250.0 parts of corn starch (trade name: "Oji Ace A", manufactured by Oji Corn Starch Co., Ltd., solid content concentration 88%) in a flask equipped with a stirrer, a condenser, a thermometer, and a nitrogen inlet tube, 11 parts of a 20% sulfuric acid aqueous solution (solid content: 2.2 parts) and 300 parts of water were added, the temperature was raised to 90° C., and the mixture was stirred for 1 hour. After that, water was added so that the solid content concentration was 15%, and the mixture was cooled to 40° C. to obtain a sulfate-modified starch (A-9).

Production Example 2-1 (Production of maleated rosin (C-2))
A reaction vessel equipped with a stirrer, a thermometer, a nitrogen inlet tube and a condenser was charged with 600.0 g of a molten Chinese gum rosin at about 160° C. and 42.0 g of maleic anhydride. C. for 2 hours, a maleated rosin (C-2) having a softening point of 97.4.degree. C. and an acid value of 234.5 mgKOH/g was obtained.

Production Example 2-2 (Production of fumarated rosin (C-3))
A reaction vessel equipped with a stirrer, a thermometer, a nitrogen inlet tube and a cooler was charged with 600.0 g of melted Chinese gum rosin at about 160°C and 42.0 g of fumaric acid, and the temperature was raised to 200°C while stirring under a nitrogen stream. to obtain a fumarated rosin (C-3) having a softening point of 104.5° C. and an acid value of 219.5 mgKOH/g.

Production Example 2-3 (Production of gum rosin ester (C-4))
663.2 parts of Chinese gum rosin and 55.6 parts of glycerin were charged into a reaction vessel equipped with a stirrer, thermometer, nitrogen inlet tube and cooler (equivalent ratio [OH _(eq) /COOH _(eq) ] = 0.91), 10 parts of Nocrac 300 (manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.) as an antioxidant, and 0.1 part of p-toluenesulfonic acid as a catalyst were added, and the mixture was heated to 270°C while stirring under a nitrogen stream. to obtain a gum rosin ester (C-4) having a softening point of 90.8° C., an acid value of 16.1 mgKOH/g and a hydroxyl value of 8.1 mgKOH/g.

Example 1
In a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen inlet tube, a thermometer and two dropping funnels, 50 parts of the polymer (A-1) (solid content), 200 parts of ion-exchanged water, an anionic interface 2 parts of an activator (trade name: "Hitenol LA10", manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 0.08 parts by weight of iron (II) sulfate heptahydrate are charged, and oxygen in the reaction vessel is purged with nitrogen. After sufficient substitution, the system was heated to 80° C. while stirring. Next, a solution obtained by dissolving 20 parts of gum rosin produced in China in a monomer mixture of 56 parts of styrene and 24 parts of acrylic acid was added to the dropping funnel (I), and the dropping funnel (II) was charged with a 35% solid content filter. An aqueous solution prepared by dissolving 10 parts of hydrogen oxide water (3.5 parts by weight with respect to the monomer component) in 100 parts of water was charged respectively, added dropwise to the system over about 2 hours, and further heated for 2 hours to complete the reaction. to obtain a surface emulsion sizing agent for papermaking having a solid concentration of 25.5%. Table 1 shows the viscosity, pH and volume average particle size of the obtained surface emulsion sizing agent for papermaking (the same applies hereinafter).

Examples 2-21, Comparative Examples 1-3
Synthesis was carried out in the same manner as in Example 1 except that the components and amounts used were changed as shown in Table 1 to obtain surface emulsion sizing agents for papermaking.

(mechanical stability)
50 g of a surface emulsion sizing agent for papermaking was weighed into a container of a Marlon type stability tester (manufactured by Shinsei Sangyo Co., Ltd.) and vigorously stirred at a temperature of 25° C., a load of 10 kg, and a rotation speed of 1000 rpm for 5 minutes. The aggregates were collected by filtration through a pre-weighed 350 mesh wire mesh. After drying for 3 hours in a circulating air dryer at 105° C., the weight of the wire mesh and aggregates was measured to obtain the solid content weight of the aggregates. The value was calculated according to Formula 1 and judged according to the following evaluation criteria.

(Formula 1) Mechanical stability (%) = (solid weight of aggregate (g)/solid weight of surface emulsion sizing agent for papermaking (g)) x 100

(Evaluation criteria)
◎: The calculated value is less than 0.5% ○: The calculated value is 0.5% or more and less than 1.0% △: The calculated value is 1.0% or more and less than 5.0% ×: The calculated value is 5 .0% or more

(Preparation of coating liquid)
Corn starch (trade name: "Oji Ace A", manufactured by Oji Corn Starch Co., Ltd.) is diluted with deionized water to a solid content concentration of 12%, and ammonium persulfate (hereinafter referred to as , APS) was added at 1.6%, and the mixture was incubated at 90°C for 20 minutes. The mixture was diluted with deionized water to a solid content concentration of 7.5% and adjusted to pH 5.0 with a 48% sodium hydroxide aqueous solution to obtain APS-modified starch. 1.47 parts of the papermaking surface emulsion sizing agent of Example 1 was mixed with 50 parts of the APS-modified starch to prepare a coating solution. The solid content concentration of the surface emulsion sizing agent for papermaking in the coating liquid was 0.88%. Further, the surface emulsion sizing agents for papermaking of Examples 2 to 21 and Comparative Examples 1 to 3 were treated in the same manner to prepare coating solutions.

(Foaming property of coating liquid)
Each coating solution was heated to 50° C. and treated with a household mixer for 2 minutes, and the height of the liquid level immediately after the treatment was measured (the initial liquid level was 60 mm).

(Preparation of coated paper and evaluation of size effect)
Using a bar coater, each coating liquid whose liquid temperature had been adjusted to 50° C. was coated on both sides of a high-quality neutral paper (Steckigt sizing degree: 0.5 seconds, basis weight: 70 g/m ² ). After that, it was dried for 1 minute with a rotary dryer at 105° C. to prepare a coated paper. The amount of the surface emulsion sizing agent for papermaking adhered to the base paper was about 0.08 g/m ² in terms of solid content, and the amount of starch adhered to the base paper was about 2 g/m ² in terms of solid content. The Stockigt sizing degree of the obtained coated paper was measured according to JIS P 8122. It means that the larger the numerical value, the better the sizing effect.

<(A) Component>
A-1: Polymer of Production Example 1-1 A-2: Polymer of Production Example 1-2 A-3: Polymer of Production Example 1-3 A-4: Corn starch (trade name: “Oji Ace A”, manufactured by Oji Corn Starch Co., Ltd.)
A-5: Tapioca starch A-6: Potato A-7: APS-modified starch of Production Example 1-4 A-8: Enzyme-modified starch of Production Example 1-5 A-9: Production Example 1- 6 Sulfuric acid-modified starch <(B) component>
・ B-1: St / BA = 70/30 (weight ratio (solid content conversion))
・ B-2: St / IBMA = 70/30 (weight ratio (solid content conversion))
・ B-3: St / BA / AA = 65 / 20 / 15 (weight ratio (solid content conversion))
・ B-4: St / BA / DM = 65 / 20 / 15 (weight ratio (solid content conversion))
*St-styrene, BA-n-butyl acrylate, IBMA-isobutyl methacrylate, AA-acrylic acid, DM-N,N-dimethylaminoethyl methacrylate <(C) component>
・C-1: Chinese gum rosin ・C-2: Maleated rosin of Production Example 2-1 ・C-3: Fumarated rosin of Production Example 2-2 ・C-4: Gum rosin ester of Production Example 2-3

Claims (9)

Having a shell portion containing a surfactant (A) and a core portion containing a polymer (B) of monomer components containing styrenes (b1) and rosins (C) ,
A surface emulsion sizing agent for papermaking , wherein component (A) is used in an amount of 50 to 200 parts by weight in terms of solid content per 100 parts by weight of components (B) and (C) combined . 2. The surface emulsion sizing agent for papermaking according to claim 1 , wherein component (A) comprises a polymer of monomer components containing styrenes (a1) and/or α-olefins (a2), or starches. 3. The surface emulsion sizing agent for papermaking according to claim 1 or 2 , wherein the monomer component constituting the component (B) further contains a (meth)acrylic acid ester (b2). The surface emulsion sizing agent for papermaking according to any one of claims 1 to 3 , wherein the monomer component constituting component (B) further contains an unsaturated monomer (b3) having a hydrophilic group. The papermaking material according to any one of claims 1 to 4 , wherein component (C) contains at least one selected from the group consisting of unmodified rosin, α,β-unsaturated carboxylic acid-modified rosin and unmodified rosin ester. Surface emulsion sizing agent. Any one of claims 1 to 5 , wherein the ratio of the components (B) and (C) used is (B)/(C) = 20/80 to 95/5 in terms of solid weight. 3. The surface emulsion sizing agent for papermaking according to . The surface emulsion sizing agent for papermaking according to any one of claims 1 to 6 , which has a volume average particle size of 50 to 300 nm. 8. The surface emulsion sizing agent for papermaking according to any one of claims 1 to 7 , wherein the monomer component constituting component (B) and component (C) are added dropwise to component (A) to effect emulsion polymerization. Production method. A coated paper comprising the surface emulsion sizing agent for papermaking according to any one of claims 1 to 7 .