JP7283262B2 - Surface sizing agent for papermaking, method for producing surface sizing agent for papermaking, and coated paper - Google Patents

Description

TECHNICAL FIELD The present invention relates to a papermaking surface sizing agent, a method for producing a papermaking surface sizing agent, 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 sizing agents for papermaking are unstable with respect to mechanical shear. In addition, there are problems such as deterioration of workability due to coating unevenness and the like, and as a result, deterioration of the sizing effect. 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 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 sizing agent for papermaking that exhibits excellent mechanical stability, little foaming, and excellent sizing effect; a method for producing the surface sizing agent for papermaking; and a coated paper.

The present inventors used a specific dehydration condensate with a focus on enhancing the sizing effect, and assumed that the use of the dehydrated condensate would deteriorate the mechanical stability. The present inventors have found that a surface sizing agent for papermaking, which has a sizing agent in the shell portion and a polymer of a specific monomer component in the core portion together with the dehydration condensate, solves the above problems, and completed the present invention. Specifically, the present invention relates to a surface sizing agent for papermaking, a method for producing a surface sizing agent for papermaking, and a coated paper as described below.

1. a shell portion containing a surfactant (A) having a weight average molecular weight of 1,000 to 500,000;
A polymer (B) of a monomer component containing styrenes (b1), a trivalent or tetravalent carboxylic acid (c1), and an aliphatic alcohol (c2-1) represented by the general formula (1) and the general formula Emulsion particles for papermaking containing emulsion particles having a core containing at least one compound (c2) selected from the group consisting of aliphatic amines (c2-2) represented by (2) and a dehydration condensate (C) surface sizing agent.
[Chemical Formula 1] R ¹ —OH (1)
(In formula (1), R ¹ represents an alkyl or alkenyl group having 6 to 22 carbon atoms.)
[Chemical Formula 2] R ² —NH—R ³ (2)
(In formula (2), R ² and R ³ each independently represent a hydrogen atom, an alkyl group having 6 to 22 carbon atoms, or an alkenyl group (excluding the case where both R ² and R ³ are hydrogen atoms) .)

2. 2. The surface sizing agent for papermaking according to 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 components (B) and (C) combined.

3. 3. The preceding item 1 or 2, wherein the component (A) comprises a polymer of monomer components containing at least one selected from the group consisting of styrenes (a1) and α-olefins (a2), and/or starches. Surface sizing agent for papermaking.

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

5. 5. The surface 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 sizing agent according to any one of the preceding items 1 to 5, wherein component (C) contains at least one selected from the group consisting of palmityl alcohol, stearyl alcohol, distearylamine and di-hardened tallowamine.

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) = 30/70 to 99/1 in terms of solid weight. A papermaking surface sizing agent as described.

8. 8. The papermaking surface sizing agent according to any one of the preceding items 1 to 7, wherein the emulsion particles have a volume average particle diameter of 50 to 300 nm.

9. 9. The method for producing a surface sizing agent for papermaking according to any one of the preceding items 1 to 8, wherein the monomer component constituting component (B) and the component (C) are added dropwise to component (A), followed by emulsion polymerization. .

10. A coated paper comprising the papermaking surface sizing agent according to any one of 1 to 8 above.

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

The surface sizing agent for papermaking of the present invention (hereinafter also simply referred to as "sizing agent") comprises a shell containing surfactant (A) (hereinafter referred to as component (A)) having a weight average molecular weight of 1,000 to 500,000 and a polymer (B) (hereinafter referred to as the (B) component) of a monomer component containing styrenes (b1) (hereinafter referred to as the (b1) component) and a specific dehydration condensate (C) (hereinafter referred to as the (C ) component and a core portion containing ). Each component will be described in detail below.

Component (A) is one of the components forming the shell of the sizing agent, and by functioning as a protective colloid, the component (A) is excellent in mechanical stability and has the effect of reducing foaming.

The component (A) has a weight average molecular weight (polyethylene oxide conversion value by gel permeation chromatography) (the same shall apply hereinafter) of usually 1,000 to 500,000. If the weight-average molecular weight is less than 1,000, the emulsifiability of components (B) and (C) tends to be poor, and if it exceeds 500,000, the viscosity of the surface sizing agent for papermaking increases, making it difficult to apply to the base paper. Workability tends to be poor. Tend. From the same point of view, it is preferably 5,000 to 100,000, more preferably 10,000 to 50,000.

The type of component (A) is not particularly limited, but in the present invention, for example, styrenes (a1) (hereinafter referred to as component (a1)) and ) and/or starches are preferably used from the viewpoint of emulsifiability with components (B) and (C).

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 the coated paper, it is usually about 15 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 size effect of coated paper, it is usually about 5 to 60% by weight, with the total of all monomer components constituting component (A) being 100% by weight. It is preferably about 10 to 50% by weight.

Either one or both of the components (a1) and (a2) may be used.

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, but examples include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, acid anhydrides, neutralized salts, half esters, and neutralized salts of half esters thereof. is mentioned. 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 5 to 80% by weight, preferably about 10 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. is 40% by weight or less, preferably 30% by weight or less.

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. is 20% by weight or less, preferably 10% by weight or less.

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) to obtain components (B) and (C). 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, (meth) ) isobutyl 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 10% by weight or less 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.

As for the polymer, the pH may be adjusted after the polymerization in order to make it easier to dissolve in water. Various known pH adjusters can be used to adjust the pH, for example, inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid; alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; alkaline earths such as calcium hydroxide. metal 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.

As for the physical properties of the obtained polymer, from the viewpoint of emulsifiability, the weight average molecular weight is preferably about 1,000 to 100,000, more preferably about 5,000 to 50,000, more preferably about 20,000 to 40,000. About 000 is more preferable.

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, and the like.

As for the physical properties of starches, from the standpoint of emulsifiability, the weight average molecular weight is preferably about 10,000 to 500,000, more preferably about 150,000 to 450,000, and more preferably about 300,000 to 400,000. More preferred.

As the starches, modified starch obtained by modifying the above unmodified starch or modified starch (hereinafter also referred to as "raw starch") with a treating agent such as inorganic peroxide, enzyme or inorganic acid can also be used.

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. About 200 mPa·s is more preferable.

Also, the weight average molecular weight of the modified starch is preferably about 10,000 to 500,000, more preferably about 15,000 to 100,000, even more preferably about 20,000 to 50,000.

The amount of component (A) to be used is usually about 20 to 200 parts by weight, preferably about 30 to 100 parts by weight, in terms of solid weight, per 100 parts by weight of components (B) and (C) combined. be. By setting it as the said numerical range, the dispersion stability of a sizing agent and the sizing effect of a coated paper can be improved.

As the component (A), a cationic surfactant, a nonionic surfactant, an anionic surfactant, or the like may be used in combination with the polymer or starch described above.

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 portion of the 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.

Component (b2) is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, and (meth)acrylic isobutyl acid, 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 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.

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 sizing agent and the sizing effect of the coated paper, the total amount of all monomer components constituting component (B) is assumed to be 100% by weight. , 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).

The component (C) comprises a trivalent or tetravalent carboxylic acid (c1) (hereinafter referred to as the (c1) component) and an aliphatic alcohol (c2-1) represented by the general formula (1) (hereinafter referred to as ( c2-1) component) and at least one compound (c2-2) represented by the general formula (2) (hereinafter referred to as (c2-2) component) selected from the group consisting of It is a dehydrated condensate with c2) (hereinafter referred to as component (c2)), and like component (B), it is one of the core components of the 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 sizing agent is improved, and contamination of coating equipment and the like can be reduced. General formulas (1) and (2) will be described later.

Component (c1) is not particularly limited as long as it is a trivalent or tetravalent carboxylic acid, and various known compounds can be used. Examples thereof include citric acid, tricarballylic acid, t-aconitic acid, trimellitic acid, pyromellitic acid, and butanetetracarboxylic acid. The carboxyl groups of these trivalent or tetravalent carboxylic acids may be acid anhydrides. The component (c1) may also be an ester or amide of a trivalent carboxylic acid or a tetravalent carboxylic acid capable of reacting with the component (c2) by transesterification or transamidation reaction. These may be used alone or in combination of two or more. Among them, citric acid is preferable because it enhances the sizing effect and is relatively inexpensive.

Component (c2-1) is an aliphatic alcohol represented by general formula (1).

[Chemical Formula 1] R ¹ —OH (1)
(In formula (1), R ¹ represents an alkyl or alkenyl group having 6 to 22 carbon atoms.)

Examples of those represented by general formula (1) include saturated fatty alcohols such as 2-ethylhexyl alcohol, octyl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol and behenyl alcohol; unsaturated fatty alcohols such as oleyl alcohol; Fatty alcohols may be mentioned. These may be used alone or in combination of two or more.

Component (c2-2) is an aliphatic amine represented by general formula (2).

[Chemical Formula 2] R ² —NH—R ³ (2)
(In formula (2), R ² and R ³ each independently represent a hydrogen atom, an alkyl group having 6 to 22 carbon atoms, or an alkenyl group (excluding the case where both R ² and R ³ are hydrogen atoms) .)

Examples of those represented by the general formula (2) include primary aliphatic amines such as octylamine, decylamine and stearylamine; Secondary aliphatic amines may be mentioned. These may be used alone or in combination of two or more.

The component (c2-1) and the component (c2-2) may be used together.

Among these components (c2), from the viewpoint of enhancing the sizing effect of the surface sizing agent, it is preferable that at least one selected from the group consisting of palmityl alcohol, stearyl alcohol, distearylamine and dihardened beef tallow amine is included, Further, distearylamine and di-cured beef tallow amine are more preferable from the viewpoint of imparting high hydrophobicity to the surface sizing agent and further enhancing the sizing effect.

The reaction of the component (c1) and the component (c2) can be carried out by dehydration condensation under the usual reaction conditions for esterification by reacting a carboxylic acid and an alcohol, and for amidation by reacting a carboxylic acid and an amine. . For example, considering the boiling point of each component, dehydration condensation may be carried out under normal pressure or reduced pressure at about 110 to 180° C. with stirring for about 1 to 24 hours. Also, if necessary, a known basic or acidic catalyst or solvent may be used. The reaction may proceed by azeotropic dehydration using a solvent such as benzene, toluene, or xylene.

When a lower ester of carboxylic acid or an amide of carboxylic acid is used as a starting material as component (c1), the same procedure can be carried out. In the transesterification, it is preferable to use a catalyst such as di-n-butyltin oxide and p-toluenesulfonic acid.

The amount of component (c1) and component (c2) used is usually such that at least one carboxyl group of component (c1) forms an ester bond and/or an amide bond with component (c2), and component (c1) It is preferable to arrange so that at least one carboxyl group remains unreacted. When a trivalent carboxylic acid is used as the component (c1), the amount of the hydroxyl group or amino group of the component (c2) is 1 to 2 equivalents per 3 equivalents of the carboxyl groups of the component (c1). do. Further, when a tetravalent carboxylic acid is used as the component (c1), the hydroxyl group or amino group of the component (c2) is 2 to 3 equivalents with respect to the 4 equivalents of the carboxyl groups of the component (c1). make it The remaining carboxyl group may exist as a carboxyl group, or may form a salt of the carboxyl group. Examples of carboxyl base salts include alkali metal salts such as sodium and potassium, and ammonium salts such as ammonia, methylamine and ethanolamine.

The physical properties of component (C) thus obtained are not particularly limited, and for example, the melting point is usually 100° C. or lower, preferably 70° C. or lower.

Also, the acid value is not particularly limited, and is usually about 10 to 200 mgKOH/g, preferably about 20 to 150 mgKOH/g. The acid value is measured according to JIS K 0070.

The use ratio [(B)/(C)] of the component (B) and the component (C) is usually about 30/70 to 99/1 in terms of solid content weight from the viewpoint of mechanical stability of the sizing agent. , preferably about 50/50 to 95/5, more preferably about 60/40 to 90/10.

The papermaking surface sizing agent of the present invention can be obtained by various known production methods. The production method is not particularly limited, and for example, a monomer component constituting component (B) and component (C) are charged into component (A), and solution polymerization, emulsion polymerization, or suspension polymerization is performed in the presence of a polymerization initiator. However, in the present invention, from the viewpoint of 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 the monomer component forming the component (C ) component dropwise for emulsion polymerization, more specifically, a method for emulsion polymerization by dropwise addition of component (B) and component (C) in the presence of component (A) and a polymerization initiator. 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 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. The amount of the polymerization initiator to be used is also 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.

In addition, a solvent may be used, if necessary, in the production of the surface 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.

Physical properties of the surface sizing agent for papermaking of the present invention are not particularly limited. For example, the volume average particle diameter of emulsion particles measured by a light scattering method is usually about 50 to 300 nm, preferably about 50 to 150 nm, more preferably about 50 to 150 nm. It is about 50 to 80 nm. With such a numerical range, the mechanical stability of the sizing agent and the sizing effect of the coated paper are balanced.

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. When adjusting the pH, various known pH adjusters can be used. 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.

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

As a coating solution containing the surface sizing agent for papermaking of the present invention, the 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 sizing agent for papermaking, and more specifically, is obtained by coating the surface of 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 hardwood pulp (LBKP) and softwood pulp (NBKP); groundwood pulp (GP) and refiner ground pulp. mechanical pulp such as (RGP) and thermomechanical pulp (TMP); waste paper pulp such as corrugated waste paper; 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.

(Weight average molecular weight)
The molecular weight was measured under the following measurement conditions by a gel permeation chromatography (GPC) method.
GPC body: Tosoh Corporation Column: Tosoh Corporation guard column TSKgel guardcolumn α 1 piece and TSK-GEL α-M 2 pieces (temperature 40 ° C.)
Eluent: 0.2 mol/L sodium nitrate buffer (sodium nitrate (manufactured by Wako Pure Chemical Industries, Ltd.)
Flow rate: 1.0 mL/min Detector:
Viscotec TDA MODEL301 (concentration detector, 90° light scattering detector and viscosity detector (temperature 40°C)) RALLS method Reference substance: Polyethylene oxide Measurement sample: Component (A) is 0.5% in terms of solid concentration Add the above-mentioned eluent to adjust the measurement sample so that it becomes pH 10 to 12, add sodium hydroxide aqueous solution until it reaches pH 10 to 12, soak it in a hot water bath at 80 ° C. or higher for 1 hour, and then adjust the pH to 6 to 8 with sulfuric acid. and diluted to 0.025% with the eluent.

(melting point)
It was measured using differential scanning calorimetry (apparatus name “EXSTAR DSC-6200”, manufactured by Seiko Instruments Inc.).

(acid value)
Measured according to JIS K 0070.

(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.

(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 total 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 ) were charged and 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%. The weight average molecular weight of component (A-1) is shown in Table 1 (same below).

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 -butylperoxy-2-ethylhexanoate (trade name "Per-Butyl O", manufactured by NOF Corporation) were charged. 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 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 added, 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))
In a flask equipped with a stirrer, condenser, dropping funnel, nitrogen inlet tube and thermometer, 70 parts of styrene, 30 parts of N,N-dimethylaminoethyl methacrylate, 42.9 parts of isopropyl alcohol, and 2, 2'-Azobisisobutyronitrile was charged in 2.5 parts, 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 introduction 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 component (C-1))
210 parts (1 mole) of citric acid monohydrate and dihydrogenated beef tallow amine (trade name "Armine 2HT", Lion Specialty Chemicals) were added to a reactor equipped with an agitator, thermometer, reflux condenser and nitrogen inlet tube. 1000 parts (2 mol) of alkyl chain length ratio C16/C18=40/60 (manufactured by Co., Ltd.) and 1252 parts of toluene were mixed, and the dehydration condensation reaction was continued for 20 hours under reflux of toluene. Toluene was distilled off from this reaction mixture under reduced pressure to obtain a dehydrated condensate (A-1) containing a diamide compound as a main component. The dehydration condensate had a melting point of 52 to 56° C. and an acid value of 55.7 mgKOH/g.

Production Example 2-2 (Production of component (C-2))
In the same reactor as in Production Example 2-1, 210 parts (1 mol) of citric acid monohydrate and stearyl alcohol (trade name “NAA-46”, stearyl alcohol/palmityl alcohol = 85/15 (%), 532 parts (2 mol) of NOF Corporation) was mixed, and the reaction system was heated to 160° C. while distilling out the water produced, and the dehydration condensation reaction was continued at the same temperature for 1.5 hours. This reaction product was cooled to obtain a dehydrated condensate (C-2) containing a diester compound as a main component. The dehydration condensate had a melting point of 48-51° C. and an acid value of 78.7 mgKOH/g.

Production Example 2-3 (Production of component (C-3))
In the same reactor as in Production Example 2-1, 176 parts (1 mol) of tricarballylic acid and 532 parts (2 mol) of stearyl alcohol (trade name “NAA-46”) were mixed, heated to 160 ° C. The dehydration condensation reaction was continued at temperature for 1.5 hours. This reaction product was cooled to obtain a dehydrated condensate (C-3) containing a diester compound as a main component. The dehydration condensate had a melting point of 48-51° C. and an acid value of 78.7 mgKOH/g.

Production Example 2-4 (Production of component (C-4))
In the same reaction apparatus as in Production Example 2-1, 176 parts (1 mol) of tricarballylic acid, 1000 parts (2 mol) of di-hardened beef tallow amine (trade name “Armine 2HT”), and 1252 parts of toluene were mixed to give toluene. The reaction was continued for 20 hours under reflux. Toluene was removed from this reaction mixture under reduced pressure to obtain a dehydrated condensate (C-4) containing a diamide compound as a main component. The dehydration condensate had a melting point of 52 to 56° C. and an acid value of 53.0 mgKOH/g.

Production Example 2-5 (Production of component (C-5))
In the same reactor as in Production Example 2-1, 174 parts (1 mol) of t-aconitic acid, 1000 parts (2 mol) of di-hardened beef tallow amine (trade name “Armine 2HT”), and 1252 parts of toluene were mixed, The reaction was continued under reflux of toluene for 20 hours. Toluene was distilled off from this reaction mixture under reduced pressure to obtain a dehydrated condensate (C-5) containing a diamide compound as a main component. The dehydration condensate had a melting point of 52 to 56° C. and an acid value of 53.0 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", weight average molecular weight: 300, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 0.08 parts by weight of iron (II) sulfate heptahydrate are charged into a reaction vessel. After sufficiently replacing oxygen in the system with nitrogen, the system was heated to 80° C. while stirring. Next, a solution obtained by dissolving 20 parts of component (C-1) in a monomer mixture of 64 parts of styrene and 16 parts of n-butyl acrylate was added to the dropping funnel (I), and the solid content was added to the dropping funnel (II). An aqueous solution prepared by dissolving 10 parts of hydrogen peroxide solution with a concentration of 35% (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 kept warm for 2 hours. Then, the reaction was completed to obtain a papermaking surface sizing agent having a solid concentration of 20.4%. The viscosity, pH, and volume average particle size of the obtained surface sizing agent for papermaking are shown in Table 1 (the same applies hereinafter).

Examples 2-22, Comparative Examples 1-4
Synthesis was carried out in the same manner as in Example 1 except that the components and amounts used were changed to those shown in Table 1 to obtain surface sizing agents for papermaking. In Comparative Example 3, only 2 parts of an anionic surfactant (Hitenol LA10) was used without using component (A) as a surfactant.

(mechanical stability)
50 g of a papermaking surface sizing agent was weighed into a container of a Marlon type stability tester (manufactured by Shinsei Sangyo Co., Ltd.) and vigorously stirred for 5 minutes at a temperature of 25 ° C., a load of 10 kg, and a rotation speed of 1000 rpm. Agglomerates were filtered through a pre-weighed 350 mesh wire screen. 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 content weight (g) of aggregate/solid content weight (g) of surface sizing agent for papermaking) 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.) was diluted with deionized water to a solid content concentration of 12%, and APS was added to 1.0% of the solid content weight of starch. 6% and incubated at 90°C for 20 minutes. The mixture was diluted with deionized water to a solid concentration of 7.5% and adjusted to pH 5.0 with a 48% aqueous sodium hydroxide solution to obtain APS-modified starch. 1.47 parts of the papermaking surface 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 sizing agent for papermaking in the coating liquid was 0.88%. Further, the surface sizing agents for papermaking of Examples 2 to 22 and Comparative Examples 1 to 4 were similarly treated 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 40 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 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 adhered starch 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 = 80/20 (weight ratio (solid content conversion))
・ B-2: St / IBMA = 80/20 (weight ratio (solid content conversion))
・ B-3: St / BA / AA = 85 / 10 / 5 (weight ratio (solid content conversion))
・ B-4: St / BA / DM = 85 / 10 / 5 (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: Dehydration condensation product of Production Example 2-1 (citric acid monohydrate (1 mol) and stearyl alcohol / palmityl alcohol = 85/15 (2 mol)) · C-2: Production Example 2- 2 (citric acid monohydrate (1 mol) and dihydrogenated beef tallow amine (2 mol)) dehydrated condensate C-3: Production Example 2-3 (tricarballylic acid (1 mol) and stearyl alcohol (2 mol) )) dehydration condensate C-4: Dehydration condensate of Production Example 2-4 (tricarballylic acid (1 mol) and dihardened beef tallow amine (2 mol)) C-5: Production Example 2-5 (t - Dehydration condensate of aconitic acid (1 mol) and dihardened tallow amine (2 mol))

Claims (9)

a shell portion containing a surfactant (A) having a weight average molecular weight of 1,000 to 500,000;
A polymer (B) of a monomer component containing styrenes (b1), a trivalent or tetravalent carboxylic acid (c1), and an aliphatic alcohol (c2-1) represented by the general formula (1) and the general formula Emulsion particles having a core containing at least one compound (c2) selected from the group consisting of aliphatic amines (c2-2) represented by (2) and a dehydration condensate (C) ,
A surface sizing agent for papermaking, wherein the ratio of component (B) and component (C) used is (B)/(C)=30/70 to 99/1 in terms of solid weight.
[Chemical Formula 1] R ¹ —OH (1)
(In formula (1), R ¹ represents an alkyl or alkenyl group having 6 to 22 carbon atoms.)
[Chemical Formula 2] R ² —NH—R ³ (2)
(In formula (2), R ² and R ³ each independently represent a hydrogen atom, an alkyl group having 6 to 22 carbon atoms, or an alkenyl group (excluding the case where both R ² and R ³ are hydrogen atoms) .) 2. The surface sizing agent for papermaking according to claim 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 components (B) and (C) combined. . The component (A) according to claim 1 or 2, wherein the component comprises a polymer of monomer components containing at least one selected from the group consisting of styrenes (a1) and α-olefins (a2), and/or starches. papermaking surface sizing agent. The papermaking surface sizing agent according to any one of claims 1 to 3, wherein the monomer component constituting component (B) further contains a (meth)acrylic acid ester (b2). The surface sizing agent for papermaking according to any one of claims 1 to 4, wherein the monomer component constituting component (B) further contains an unsaturated monomer (b3) having a hydrophilic group. 6. The surface sizing agent for papermaking according to any one of claims 1 to 5, wherein component (C2) contains at least one selected from the group consisting of palmityl alcohol, stearyl alcohol, distearylamine and di-hardened tallowamine. The surface sizing agent for papermaking according to any one of claims 1 to 6 , wherein the emulsion particles have a volume average particle diameter of 50 to 300 nm. 8. Production of the surface sizing agent for papermaking according to any one of claims 1 to 7 , characterized in that the monomer component constituting component (B) and component (C) are dropped into component (A) and emulsion polymerization is carried out. Method. A coated paper comprising the surface sizing agent for papermaking according to any one of claims 1 to 7 .