JP2006342467A - Surface-sizing agent for papermaking and printing paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an emulsion type surface-sizing agent capable of solving the conventional problems of foaming, mechanical stability and especially splash, without damaging an original objective of paper sizing. <P>SOLUTION: This surface-sizing agent for papermaking is provided by containing emulsion obtained by polymerizing (b) monomers containing an unsaturated mono- or poly-basic acid monomer and unsaturated hydrophobic monomer in an aqueous solution containing at least 1 kind selected from a group consisting of (A) a water soluble polymer obtained by polymerizing (a) monomers containing the unsaturated mono- or poly-basic acid monomer and unsaturated hydrophobic monomer, (B) an unsaturated mono- or poly-basic acid-modified rosin polyhydric alcohol ester, (C) an 8-36C alkyl succinic anhydride alkali salt and/or 8-36C alkenyl succinic anhydride alkali salt and (D) an alkenyl succinic acid-modified starch. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an emulsion-type surface sizing agent for papermaking and printing paper.

  The emulsion-type surface sizing agent for papermaking has advantages such as excellent handling properties, less foaming, and a high solid content, so that a size effect can be obtained in a small amount. However, emulsion-type surface sizing agents for papermaking use a high-speed surface coating method such as size press coating or gate roll coating method, and the sizing agent dilution splashes and pollutes the work space. There is a problem of splash that lowers. In addition, there is a problem that emulsion particles are destroyed at the time of coating and wrinkles are formed, or the sizing agent diluent is strongly foamed at the time of coating and the operability is lowered. The problem of wrinkles becomes particularly serious when the filler such as calcium carbonate is eluted from the inside of the paper into the coating liquid (sizing agent dilution liquid) and the hardness of the dilution liquid is increased.

  These problems have been conventionally addressed from the viewpoint of the surfactant and protective colloid of the emulsion. However, to the best of the applicant's knowledge, the foaming, mechanical stability, in particular, without losing the original purpose of the paper size effect (for example, without a decrease or fluctuation of the size effect over time) There is still no example that could solve the splash problem. For example, when a surfactant is used, the amount used is usually increased because a low molecular weight one is used, and the problem of foaming increases. Further, when general polyvinyl alcohol is used as the protective colloid, the mechanical stability is improved, but the paper surface becomes hydrophilic and the size effect is impaired. In addition, when an anionic synthetic polymer as disclosed in Patent Document 1 is used as a protective colloid, foaming during coating can be suppressed to some extent, but the size effect is inherently insufficient.

JP-A-8-246391

  The problem to be solved by the present invention is an emulsion-type surface sizing agent for papermaking, which can suitably solve the problems of foaming, mechanical stability, especially splash without impairing the original purpose of imparting a size effect. Is to provide. In addition, a further object of the present invention is to provide a printing paper excellent in various size effects (drop size degree, steecht degree degree, etc.), etc., which is formed by coating the paper surface sizing agent on the paper surface. is there.

  As a result of intensive studies, the present applicant has determined that a specific vinyl-based monomer in an aqueous solution containing a specific anionic polymer and at least one selected from a specific rosin ester, succinic acid, and starch is present. It has been found that the above problem can be solved by using an emulsion obtained by emulsion polymerization of a body as a surface sizing agent for papermaking.

That is, the present invention polymerizes a monomer (a) containing an unsaturated basic acid monomer and an unsaturated hydrophobic monomer (hereinafter sometimes abbreviated as “monomer for polymer (a)”). Water-soluble polymer (A) (hereinafter sometimes abbreviated as water-soluble polymer (A)) and unsaturated basic acid-modified rosin ester (B) (hereinafter abbreviated as rosin ester (B)). A) alkyl (C8-36) succinic anhydride alkali salt and / or alkenyl (C8-36) succinic anhydride alkali salt (C) (hereinafter referred to as succinic acid (C)), and alkenyl succinic acid modification Contains an unsaturated basic acid monomer and an unsaturated hydrophobic monomer in an aqueous solution containing at least one selected from the group consisting of starch (D) (hereinafter sometimes abbreviated as starch (D)) Monomer (b) (hereinafter, monomer for emulsion polymerization ( ) And it is abbreviated) papermaking surface sizing agent comprising an emulsion, obtained by emulsion polymerization of: printing paper the formulation paper for surface sizing agent is formed by coating the paper relates.

  The emulsion constituting the sizing agent of the present invention is less foamed in a high-speed surface coating method such as size press coating or gate roll coating method, and has mechanical stability (particularly mechanical stability under the hard water condition). ) Is almost free from wrinkles and the splash is not generated, so that the operability is not impaired. In addition, the sizing agent of the present invention can impart a stable and excellent sizing effect (drop sizing degree, Steecht sizing degree, etc.) to paper over time. In addition, the sizing agent of the present invention is influenced by raw materials such as pulp, filler, internal sizing agent, internal paper strength enhancer, yield improver, and internal chemicals, and paper making pH, paper making temperature, paper machine type, etc. Little affected by papermaking conditions. In addition, the sizing agent can be applied to various types of paper such as printing paper, book paper, PPC paper, and newsprint paper, and particularly imparts ink jet aptitude such as excellent print density, low feathering, and low bleeding to the paper. Therefore, it is suitable for paper for inkjet printing.

The water-soluble polymer (A) is used as a polymer emulsifier in the present invention, and in particular, the above-mentioned splash problem can be preferably solved.

As the unsaturated basic acid monomer in the monomer for polymer (a), various known monomers can be used without any particular limitation. Specifically, unsaturated monobasic acid monomers such as (meth) acrylic acid; crotonic acid, itaconic acid, itaconic acid half ester, maleic acid, maleic acid half ester, maleic anhydride, fumaric acid, muconic acid , An unsaturated polybasic acid monomer such as citraconic acid; and one kind of these alkali metal salts, ammonia salts, organic amine salts and the like can be used alone or in appropriate combination of plural kinds. . In addition, the said half ester means what formed by ester-bonding polyhydric carboxylic acid and the alcohol which has a C1-C18 alkyl group. The alkyl group may be linear, branched or cyclic, and specifically includes, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, and an n-butyl group. Group, i-butyl group, t-butyl group, neopentyl group, n-hexyl group, cyclohexyl group, 2-ethylhexyl group, decyl group, palmityl group, stearyl group and the like. As the unsaturated basic acid monomer, (meth) acrylic acid and / or a neutralized salt thereof is preferable because the viscosity of the sizing agent coating liquid is easily increased, and therefore, the problem of splash is easily solved. .

As the unsaturated hydrophobic monomer in the polymer monomer (a), various known monomers can be used without any particular limitation. Specifically, for example, styrenes such as styrene, α-methylstyrene, and vinyl toluene; (meth) acrylic acid alkyl esters having an alkyl group having 1 to 18 carbon atoms; aromatic groups such as benzyl group and allyl group (Meth) acrylic acid esters having; (meth) acrylic acid hydroxyalkyl esters having a hydroxyl group such as 2-hydroxyethyl group and 2-hydroxypropyl group; (meth) acrylonitrile; vinyl esters such as vinyl acetate and vinyl propionate Class: C6-C22 α-olefins which may be branched; C1-C22 alkyl vinyl ethers may be used alone or in appropriate combination. As the unsaturated hydrophobic monomer, styrenes and / or (meth) acrylic acid alkyl esters are particularly preferable from the viewpoint of size effect.

  The monomer for polymer (a) is an unsaturated basic acid monomer of about 20 to 80% by weight (preferably about 25 to 75% by weight, more preferably 35 to 65% by weight), unsaturated hydrophobic acid. It is preferable to contain about 80 to 20% by weight (preferably about 75 to 25% by weight, more preferably 65 to 35% by weight) of a functional monomer. When the content of the unsaturated basic acid monomer is less than 20% by weight, the water-soluble copolymer (A) is difficult to be water-soluble, so that aggregates are formed in the reaction system during the emulsion polymerization described later. It tends to occur easily. On the other hand, when the content exceeds 80% by weight, the hydrophilicity of the water-soluble copolymer (A) becomes too high, and the obtained emulsion (surface sizing agent for papermaking) hardly exhibits a high size effect. There is a tendency.

In addition, in this invention, unsaturated monomers other than the above can be contained as a monomer for polymers (a) as needed. Specifically, for example, a nonionic unsaturated monomer such as vinyl pyrrolidone, a sulfonic acid-containing anionic unsaturated monomer such as vinyl sulfonic acid or 2-acrylamido-2-methylpropane sulfonic acid, or an alkali salt thereof, etc. Various known acrylamide monomers described later can be contained alone or in appropriate combination. The amount of the other unsaturated monomer used is not particularly limited as long as the size effect aimed by the present invention can be maintained, but is usually 0 to the total weight of the monomer for polymer (a). About 10% by weight.

  The manufacturing method of a water-soluble polymer (A) is not specifically limited, What is necessary is just to utilize various well-known polymerization means. Specifically, for example, a predetermined amount of the monomer is charged into a reaction vessel, and then water (for example, soft water) and / or various organic solvents, a known polymerization initiator, and a chain transfer agent as necessary are charged as a solvent. Thereafter, the temperature of the reaction system is raised to about 20 to 140 ° C. with stirring, and then the polymerization reaction is performed at the same temperature for about 2 to 12 hours, and neutralization treatment is performed using a neutralizing agent as necessary. Can be manufactured. The reaction system is preferably a nitrogen atmosphere.

  As the organic solvent, various known solvents can be used without any particular limitation. Specifically, for example, lower alcohols such as ethyl alcohol and isopropyl alcohol; aromatic hydrocarbons such as benzene and toluene; lower ketones such as acetone and methyl ethyl ketone; ethyl acetate, chloroform and dimethylformamide alone, or They can be used in appropriate combinations. In consideration of environmental load and occupational hygiene, it is preferable to finally remove these organic solvents from the reaction system as much as possible by various known means such as vacuum distillation.

  As the polymerization initiator, various known ones can be used without particular limitation. Specifically, for example, inorganic peroxides such as hydrogen peroxide, ammonium persulfate, and potassium persulfate; organic peroxides such as benzoyl peroxide, dicumyl peroxide, and lauryl peroxide; 2,2′-azobisiso Azo compounds such as butyronitrile and dimethyl-2,2′-azobisisobutyrate can be used alone or in appropriate combination. When the polymerization initiator is an inorganic / organic peroxide, various known reducing agents such as sodium sulfite and sodium thiosulfate may be used in combination, and the reaction system may be a redox system. In addition, the usage-amount of this polymerization initiator is about 0.01 to 5 weight% normally with respect to the total weight of a monomer (a).

  For the purpose of adjusting the water-soluble polymer (A) to a desired molecular weight and viscosity, various known materials can be used without particular limitation as the chain transfer agent. Specifically, for example, alkyl mercaptan chain transfer agents such as n-dodecyl mercaptan, n-octyl mercaptan, tertiary decyl mercaptan, n-octadecyl mercaptan, n-hexadecyl mercaptan, 2-mercaptobenzothiazole, bromotrichloromethane , Alpha-methylstyrene dimer or the like can be used alone or in appropriate combination. In addition, the usage-amount of this chain transfer agent is about 0 to 5 weight% normally with respect to the total weight of a monomer (a).

          As the neutralizing agent, various known ones can be used without particular limitation. Specifically, for example, alkali metals such as sodium hydroxide and potassium hydroxide; ammonia such as ammonia and ammonium carbonate: about 1 to 12 carbon atoms such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine and monobutylamine Aliphatic amines; alicyclic amines such as cyclohexylamine; aromatic amines such as aniline can be used alone or in appropriate combination. Among these neutralizing agents, alkali metals and ammonia are particularly preferable from the viewpoint of convenience. The carboxyl group of the water-soluble polymer (A) is preferably at least 50% or more neutralized, more preferably 80 to 100% in consideration of water solubility. The neutralization method is not particularly limited, and the neutralization treatment may be performed after the water-soluble polymer (A) is produced as described above, or an unsaturated basic acid monomer directly neutralized is used. Thus, the water-soluble polymer (A) may be produced.

The water-soluble polymer (A) thus obtained has a weight average molecular weight of usually about 1,000 to 1,000,000, preferably 5,000 to 100,000 from the viewpoint of size effect and operability. . When the weight average molecular weight is less than 1,000, the size effect tends to be insufficient. On the other hand, when the weight average molecular weight exceeds 100,000, aggregates tend to be generated in the system during the emulsion polymerization described later. The water-soluble polymer (A) usually has a viscosity of about 10 to 5,000 mPa · s (25 ° C.) at a solid content concentration of 20% by weight and a pH of about 7.5 to 10.5.

As described above, the surface sizing agent for papermaking of the present invention comprises at least one selected from the group consisting of a water-soluble polymer (A), rosin ester (B), succinic acid (C) and starch (D). Containing an emulsion obtained by emulsion polymerization of the emulsion polymerization monomer (b). In the present invention, rosin ester (B), succinic acid (C), and starch (D) are all used as protective colloids during emulsion polymerization.

The amount of the water-soluble polymer (A) used is usually about 2 to 50% by weight, preferably 5 to 25% by weight in terms of solid content, based on the total weight of the monomer for emulsion polymerization (b). It is preferable to do this. When the amount used is less than 2% by weight, the resulting paper sizing agent tends to make it difficult to eliminate the splash problem, and when the amount used exceeds 50% by weight, the size effect is sufficient. It tends to disappear.

The rosin ester (B) is a reaction product comprising the same unsaturated basic acid monomer as the polymer monomer (a), rosins and polyhydric alcohols as constituents, and the present invention. Then, various known materials can be used without any particular limitation.

Various known rosins can be used without particular limitation. Specifically, for example, gum rosin, wood rosin, and toll whose main constituents are various resin acids (such as abietic acid, levopimaric acid, neoabietic acid, parastrinic acid, pimaric acid, isopimaric acid, sandaracopimalic acid, dehydroabietic acid) Various known natural rosins such as oil rosin and various derivatives (purified products, disproportionated products, hydrogenated products, formylated products, polymerized products (polymerized rosins)) of these natural rosins alone or in appropriate combination Can be used.

The unsaturated basic acid monomer is at least one selected from the group consisting of (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid and neutralized salts thereof from the viewpoint of reactivity with the rosins. Species are preferred.

As the polyhydric alcohol, various known alcohols can be used without particular limitation. Specifically, for example, ethylene glycol, diethylene glycol, 1,2-dihydroxypropane, 1,3-dihydroxypropane, 1,2-dihydroxybutane, 1,3-dihydroxybutane, 2,3-dihydroxybutane, neopentyl glycol, Dihydric alcohols such as 1,4-bis-hydroxymethyl-cyclohexane, 1,6-hexanediol, octene glycol, polyethylene glycol; glycerol, 1,2,4-butanetriol, triethylene glycol, tripropylene glycol, 3- Trivalent alcohols such as methylpentane-1,3,5-triol and glycerin; tetrahydric alcohols such as diglycerin and pentaerythritol; pentahydric and higher alcohols such as pentatriol and sorbitol alone or in appropriate combination It is possible to use Te Align. As the polyhydric alcohol, pentaerythritol is preferable from the viewpoint of mechanical stability of the emulsion.

The production method of the rosin ester (B) is not particularly limited, and various known means may be followed. Specifically, for example, (a) a method in which a product obtained by subjecting the unsaturated basic acid monomer to Diels-Alder addition reaction with the rosin is further esterified with the polyhydric alcohol; A method of reacting the rosin with a hydroxyl group of a polyester obtained by reacting a saturated basic acid monomer with the polyhydric alcohol; (c) the unsaturated basic acid monomer, rosin or polyhydric alcohol. It can be obtained by a method of reacting simultaneously.

The rosin ester (B) is determined in consideration of the mechanical stability of the resulting emulsion, and it is usually preferable that the acid value is adjusted to about 60 to 400 mgKOH / g, particularly 80 to 260 mgKOH / g. The softening point is usually about 100 to 200 ° C, particularly preferably 110 to 185 ° C. The amount of the rosin ester (B) used is usually about 5 to 50% by weight, preferably 10 to 30% by weight in terms of solid content, based on the total weight of the monomer (b) for emulsion polymerization. Is preferred. When the amount used is less than 5% by weight, the mechanical stability of the resulting emulsion tends to be insufficient, and when the amount used is greater than 50% by weight, the size effect of the resulting paper tends to be insufficient. It is in.

As the succinic acid (C), various known ones can be used without particular limitation. Specifically, for example, a substituted succinic acid having an alkyl group or an alkenyl group having about 8 to 36 carbon atoms, preferably about 12 to 30 carbon atoms, particularly preferably about 12 to 20 carbon atoms and / or an alkenyl group having the same carbon number. Examples include salts of acids (preferably at least one of salts made of alkali metals, ammonia and organic amines). Such an alkenyl group and / or alkenyl group may be linear or branched, and specifically includes, for example, an octyl group, a nonyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, and a heptadecyl group. , Octadecyl group, eicosyl group, octenyl group, 7-hexadecenyl group, 9-octadecenyl group, palmityl group, stearyl group and the like. If the carbon number is less than 8, the effect of suppressing foaming at the time of coating tends to be insufficient, and if it is greater than 36, the water dispersibility and mechanical stability of the resulting emulsion tend to decrease. . As the succinic acid (C), octadecyl succinic anhydride neutralized salt (especially sodium salt) is preferable from the viewpoint of availability.

The amount of succinic acid (C) used is usually in the range of about 1 to 10% by weight, preferably in the range of 2 to 8% by weight in terms of solid content, based on the total weight of the monomer for emulsion polymerization (b). It is preferable to do this. When the amount used is less than 1% by weight or more than 10% by weight, the effect of suppressing foaming at the time of coating the resulting papermaking surface sizing agent and the size effect of the formed paper tend to be insufficient.

  Starch (D) is an alkenyl (anhydrous) succinic acid containing various known starches (dextrin) containing an alkenyl group having about 8 to 36 carbon atoms, preferably about 12 to 30 carbon atoms, and particularly preferably 12 to 20 carbon atoms. It is a denatured hydrophobic substance. As the starch (D), those having a viscosity at a solid content concentration of 15% of about 100 mPa · s (25 ° C.) are preferable because they are easy to handle. As a commercial product of starch (D), for example, octenyl succinate dextrin (trade name “Natural Nisku DP”: manufactured by Nissho Chemical Co., Ltd.) and octenyl succinate corn starch (trade name “Octier”: manufactured by Nissho Chemical Co., Ltd.) ) Etc. are available. In addition, even if normal dextrin type starch is used instead of starch (D), the surface sizing agent for papermaking which can express sufficient size effect is not obtained.

The amount of starch (D) used is usually in the range of about 1 to 10% by weight, preferably 2 to 8% by weight in terms of solid content, based on the total weight of the monomer for emulsion polymerization (b). Is preferred. When the amount used is less than 1% by weight or more than 10% by weight, foaming tends to increase when the resulting paper sizing agent is applied, and the size effect of the printing paper is not sufficient. There is a tendency.

The monomer for emulsion polymerization (b) is the same as the monomer for polymer (a), but from the viewpoint of the size effect, the unsaturated basic acid monomer is (meth) acrylic acid and / or The neutralized salt is preferable, and the unsaturated hydrophobic monomer is preferably styrene and / or (meth) acrylic acid alkyl ester. For the same reason, the emulsion polymerization monomer (b) contains about 2 to 20% by weight of unsaturated basic acid monomer (preferably 4 to 10% by weight) and 98% of unsaturated hydrophobic monomer. It is preferable to contain about -80 wt% (preferably 96-84 wt%). If the amount of the unsaturated basic acid monomer used is less than 2% by weight, the mechanical stability of the resulting emulsion tends to be reduced, and if the amount used exceeds 20% by weight, the printing paper The size effect tends to be insufficient.

Further, the monomer for emulsion polymerization (b) may contain an unsaturated monomer other than the above. In particular, in order to improve the mechanical stability of the obtained emulsion (particularly, the mechanical stability when the emulsion is diluted with hard water), the acrylamide monomer can be preferably used. As the acrylamide monomer, various known monomers can be used without particular limitation. Specifically, for example, (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl ( N-substituted monoalkyl (meth) such as meth) acrylamide, N-isopropyl (meth) acrylamide, N-tertiary butyl (meth) acrylamide, N-lauryl (meth) acrylamide, and N-cyclohexyl substituted alkyl (meth) acrylamide Acrylamides; N, N-dimethyl (meth) acrylamide, N, N-diisopropyl (meth) acrylamide, N, N-ditertiary butyl (meth) acrylamide, N, N-dilauryl (meth) acrylamide, N, N-diter Shary Octyl (Meta) A N-substituted dialkyl (meth) acrylamides such as rilamide and N-substituted dialkyl (meth) acrylamide such as N, N-dicyclohexyl (meth) acrylamide; diacetone acrylamide or the like may be used alone or in appropriate combination. it can. Among these, (meth) acrylamide is preferable from the viewpoint of availability. The amount of the acrylamide monomer used is less than 10% by weight based on the total weight of the water-soluble polymer (A). The nonionic unsaturated monomer, the sulfonic acid-containing anionic unsaturated monomer, or an alkali salt thereof may be used in combination, and these are usually added to the total weight of the emulsion polymerization monomer (b). About 0 to 10% by weight may be used.

The method for producing the emulsion contained in the paper size sizing agent of the present invention is not particularly limited, and various known emulsion polymerization methods may be followed. For example, a predetermined amount of at least one selected from (B) to (D) and (A) are charged into a reaction vessel equipped with a suitable heating device and a stirrer, and then the emulsion polymerization monomer ( b), water (soft water, etc.), an organic solvent, a polymerization initiator, a chain transfer agent as required, and various known emulsifiers as necessary, and the reaction system heated under stirring to emulsify What is necessary is just to superpose | polymerize. In addition, as long as said (A) and said (B)-(D) exist in the reaction system in the case of the said emulsion polymerization, the preparation order of each raw material is not specifically limited. For example, during emulsion polymerization of the emulsion polymerization monomer (b), (A) to (D) may be added dropwise to the reaction system simultaneously or separately. The organic solvent, polymerization initiator, and chain transfer agent are the same as those used in the production of (A). Further, in consideration of water dispersibility and mechanical stability of the emulsion obtained by emulsion polymerization of the emulsion polymerization monomer (b), it is usually 50% or more, preferably 80 to 100% by weight neutralized. Is preferred. Such neutralization may be performed at the time of the unsaturated basic acid monomer of the emulsion polymerization monomer (b). As the neutralizing agent, the same ones as described above can be used, but the alkali metals and ammonia are preferable. The reaction conditions during the emulsion polymerization are not particularly limited, but the reaction temperature is usually about 40 to 150 ° C. and the reaction time is about 2 to 12 hours. Moreover, when using an organic solvent as a cosolvent at the time of emulsion polymerization, it is preferable to remove to some extent by distillation under reduced pressure.

The emulsifier used in the production method is not particularly limited, and various known ones can be used. Specifically, for example, various known anionic and nonionic surfactants are preferable, and reactive emulsifiers having the ionicity can also be used. Note that it is not preferable to use only a cationic surfactant as an emulsifier because aggregates tend to be generated in the reaction system during emulsion polymerization.

Examples of the anionic surfactant include alkyl sulfonates, alkyl sulfosuccinates, α-olefin sulfonates, dialkyl sulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, and polyoxyethylene alkyl ether sulfates. Polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene alkyl ether sulfosuccinate, polyoxyethylene styryl phenyl ether sulfosuccinate, naphthalene sulfonic acid formalin condensate, etc. can be used alone or in appropriate combination. In addition, as a salt, the salt by the said alkali metal, ammonium, and an alkylamine is preferable.

Examples of the nonionic surfactant include polyethylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene styryl phenyl ether, polyoxyethylene sorbitan fatty acid ester and the like. Examples of the anionic surfactant include alkyl sulfates, alkyl benzene sulfonates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, dialkyl sulfosuccinate esters, alkyl sulfonates, polyoxyethylene alkyls. Ether sulfosuccinate, polyoxyethylene styryl phenyl ether sulfosuccinate ester salt, polyoxyethylene alkyl ether phosphate ester, α-olefin sulfonate, naphthalene sulfonate formalin condensate, polyoxyethylene alkylphenyl ether sulfate ester, etc. Can be illustrated.

As the reactive emulsifier, a surfactant having a polymerizable functional group in the molecule (for example, see JP-A-2003-293288) can be particularly preferably used.

The amount of the above-mentioned various emulsifiers is usually 10% by weight or less, preferably 5% by weight or less, based on the total weight of the emulsion polymerization monomer (b). When the content exceeds 10% by weight, foaming tends to increase when the obtained paper sizing agent is applied to paper.

In the aqueous solution containing the rosin ester (B) and the water-soluble polymer (A), the paper surface sizing agent obtained by emulsion polymerization of the emulsion polymerization monomer (b) is particularly excellent in mechanical stability. Further, an excellent size effect can be imparted to the formed paper. The surface sizing agent for papermaking, which is obtained by emulsion polymerization of the emulsion polymerization monomer (b) in an aqueous solution containing the succinic acid (C) and the water-soluble polymer (A), particularly suitably suppresses foaming during coating. it can. Moreover, the surface sizing agent for papermaking, which is obtained by emulsion polymerization of the monomer (b) for emulsion polymerization in an aqueous solution containing starch (D) and a water-soluble polymer (A), has an excellent sizing effect on paper. Can be granted.

  The emulsion thus obtained usually has a yellowish cloudy appearance, has a pH of about 7.5 to 8.5, a viscosity of about 5 to 30 mPa · s (25 ° C.) at a solid content concentration of 25% by weight, and 60 It has an average primary particle diameter of about ~ 200 nm.

The sizing agent of the present invention contains the emulsion. In practical use, the solid content concentration of the emulsion is usually about 0.001 to 2% by weight, preferably 0.05 to 0.5% by weight. It is used as a diluted solution so diluted. In the sizing agent of the present invention, various known additives can be used as necessary. Specifically, for example, starches such as oxidized starch, phosphate esterified starch, enzyme-modified starch, and cationized starch, celluloses such as carboxymethyl cellulose, polyvinyl alcohols, polyacrylamides, sodium alginate and the like are highly soluble in water. Molecules can be used as paper strength enhancers. In addition, various known anti-Nepari agents, anti-slip agents, antiseptics, rust inhibitors, pH adjusters, antifoaming agents, thickeners, fillers, antioxidants, water resistance agents, film-forming aids, pigments, dyes Etc. can be added. Moreover, various known other sizing agents and emulsion sizing agents can be used in combination as required. Further, the water-soluble polymer (A) can be further added as an additive to the sizing agent of the present invention, whereby the ink jet suitability can be further improved. In this case, among the water-soluble polymers (A), a styrene-maleic acid copolymer and a (meth) acrylic acid-styrene-maleic acid copolymer are preferable.

The printing paper of the present invention is obtained by coating the sizing agent on the surface of various known papers. The type of paper is not particularly limited, and various known types can be selected without particular limitation. Specifically, for example, recording paper such as foam paper, PPC paper, heat-sensitive recording base paper, pressure-sensitive recording base paper, and base paper for the base paper, art paper, cast coated paper, high-quality coated paper, kraft paper, pure white Use wrapping paper such as roll paper, other paper (note paper) such as notebook paper, book paper, printing paper, and newsprint paper, paperboard for paper containers such as manila balls, white balls, chip balls, and paperboards such as liners. Can do. Also, the coating method is not particularly limited, and various known methods can be used without particular limitation. Specifically, for example, an impregnation method, a size press method, a gate roll method, a bar coater method, a calendar method, a spray method, and the like can be used. Incidentally, the coating amount of the sizing agent is not particularly limited, usually 0.001~2g / m ² approximately by solids weight basis, preferably from 0.005 to 0.5 / m ^2.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to these. In each example, all parts and% are based on weight unless otherwise specified.

Preparation Example 1 (Synthesis of water-soluble polymer (A))
A reaction vessel equipped with a stirrer, a reflux condenser, and a nitrogen introduction tube was charged with 100 parts of soft water and 75 parts of isopropyl alcohol under a nitrogen stream, and the system was heated to 80 ° C. while stirring. Next, a solution obtained by mixing 55 parts of acrylic acid and 45 parts of styrene in a reaction vessel and an aqueous polymerization initiator solution obtained by dissolving 5 parts of potassium persulfate in 120 parts of water were dropped into the system over about 3 hours. The system was then kept warm for 2 hours to complete the reaction. Then, isopropyl alcohol was distilled off, and after cooling, 46.4 parts of 28% aqueous ammonia solution (100 mol% with respect to acrylic acid) was added, and further diluted with water to adjust the solid content concentration to be wt%. A water-soluble polymer (A) having a viscosity at 25 ° C. of 1100 mPa · s was obtained.

Preparation Example 2 (Preparation of rosin ester (B))
An unsaturated polybasic acid-modified rosin ester having an acid value of 110 mg KOH / g (trade name “Marquide 3002” manufactured by Arakawa Chemical Industries, Ltd.) and 28% aqueous ammonia (equivalent) were added to the same reaction vessel as in Preparation Example 1, and nonvolatile A 20% aqueous solution with a pH of 9.0 was obtained.

Production Example 1
In a reaction vessel similar to Preparation Example 1, 50 parts of the water-soluble polymer (A), 25 parts of the rosin ester (B) and 290 parts of water were charged under a nitrogen stream, and further 8 parts of styrene, 84 parts of butyl methacrylate, 6 parts of methacrylic acid, 2 parts of acrylamide, 0.5 part of N-dodecyl mercaptan, 5.8% caustic soda 5.8 (100 mol% neutralized with respect to methacrylic acid), anionic surfactant (Neohaitenol S-70: A mixture consisting of 4 parts from Daiichi Kogyo Seiyaku Co., Ltd. was charged. Next, the air in the reaction system was sufficiently replaced with nitrogen, and the mixture was further heated to 70 ° C., and then a radical polymerization initiator (an aqueous solution in which 2.5 parts of ammonium persulfate was dissolved in 8 g of water) was added to the reaction vessel. did. Next, after emulsion polymerization for 20 minutes, the temperature was raised to 80 ° C., and the polymerization reaction was allowed to proceed in the temperature range of 80 to 85 ° C. for 2 hours. Thus, an emulsion having a pH of 8.4, a solid content concentration of 25% by weight, and a viscosity of 15 mPa · s / 25 ° C. was obtained.

Production Example 2
In a reaction vessel similar to Production Example 1, 4 parts of an anionic surfactant (Neohaitenol S-70: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 290 parts of water, 8 parts of styrene, 84 parts of butyl methacrylate under a nitrogen stream. 1 part, methacrylic acid 6 parts, acrylamide 2 parts, N-dodecyl mercaptan 0.5 part, 48% caustic soda 5.8 (100 mol% neutralized with respect to methacrylic acid), and then the water-soluble polymer (A 50 parts of succinic acid (C) was charged with 12.5 parts of sodium salt of octadecyl succinic anhydride having a solid content of 40% by weight. After sufficiently replacing oxygen in the reaction system with nitrogen, the temperature of the mixture was raised to 70 ° C., and a radical polymerization initiator (an aqueous solution in which 2.5 parts of ammonium persulfate was dissolved in 8 g of water) was added to the reaction vessel. did. Next, after emulsion polymerization for 20 minutes, the temperature was raised to 80 ° C., and the polymerization reaction was allowed to proceed in the temperature range of 80 to 85 ° C. for 2 hours. Thus, an emulsion having a pH of 8.6, a solid content concentration of 25.5%, and a viscosity of 18 mPa · s / 25 ° C. was obtained.

Production Example 3
In a reaction vessel similar to Production Example 1, 4 parts of an anionic surfactant (Neohaitenol S-70: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 290 parts of water, 8 parts of styrene, 84 parts of butyl methacrylate under a nitrogen stream. 1 part, methacrylic acid 6 parts, acrylamide 2 parts, N-dodecyl mercaptan 0.5 part, 48% caustic soda 5.8 (100 mol% neutralized with respect to methacrylic acid), and then the water-soluble polymer (A ) 50 parts, and dextrin octenyl succinate dextrin (product name “Naturnics DP”, manufactured by Nissho Chemical Co., Ltd.) having a solid content concentration of 50% by weight was charged as starch (D). After sufficiently replacing oxygen in the reaction system with nitrogen, the temperature of the mixture was raised to 70 ° C., and a radical polymerization initiator (an aqueous solution in which 2.5 parts of ammonium persulfate was dissolved in 8 g of water) was added to the reaction vessel. did. Next, after emulsion polymerization for 20 minutes, the temperature was raised to 80 ° C., and the polymerization reaction was allowed to proceed in the temperature range of 80 to 85 ° C. for 2 hours. Thus, an emulsion having a pH of 8.2, a solid content concentration of 25.7%, and a viscosity of 13 mPa · s / 25 ° C. was obtained.

Comparative production example 1
In a reaction vessel similar to Production Example 1, 25 parts of the rosin ester (B), 290 parts of water, 8 parts of styrene, 84 parts of butyl methacrylate, 6 parts of methacrylic acid, 2 parts of acrylamide, N-dodecyl mercaptan under a nitrogen stream. 0.5 parts, 48% caustic soda 5.8 (100 mol% neutralized with respect to methacrylic acid), anionic surfactant (Neohaitenol S-70: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 4 parts The mixture was charged. Next, the air in the reaction system was sufficiently replaced with nitrogen, and the mixture was further heated to 70 ° C., and then a radical polymerization initiator (an aqueous solution in which 2.5 parts of ammonium persulfate was dissolved in 8 g of water) was added to the reaction vessel. did. Next, after emulsion polymerization for 20 minutes, the temperature was raised to 80 ° C., and the polymerization reaction was allowed to proceed in the temperature range of 80 to 85 ° C. for 2 hours. Thus, an emulsion having a pH of 7.9, a solid content concentration of 25.4%, and a viscosity of 8 mPa · s / 25 ° C. was obtained.

(Preparation of sizing solution)
Each of the emulsions obtained in Production Examples 1 to 3 and Comparative Production Example 1 was subjected to gelatinization with water having a hardness of 0 ° dH and 10% (trade name “Oji Ace A”: Oji Corn Starch Co., Ltd. The sizing agent dilutions 1 to 4 were prepared so that the solid content concentration of the emulsion was about 0.1 wt% and the solid content concentration of the oxidized starch was about 4.0 wt%. For reference, three of the oxidized starches? Was used to prepare a starch diluted solution prepared with water having a hardness of 0 ° dH so that the solid content concentration was about 4.0% by weight.

(Creation of test paper)
Neutral high quality paper (weighing 70 g / m ² , steecht size degree 0 second) is used as a base paper, and the sizing agent is diluted with a lab size press coating machine (test size press, Kumagai Riki Kogyo Co., Ltd.). The liquids 1 to 4 and the starch diluted solution were each applied at about 65 g / m ² . Each coated paper was then dried for 1 minute at 105 ° C. with a rotary drum dryer to obtain a test paper.

Examples, Comparative Examples, Reference Examples <Measurement of Steecht Size>
Using each test paper obtained by the above-described method, the Steecht sizing degree (second) was measured according to JIS P8122. The higher the number, the better the size. The results are shown in Table 1.

<Evaluation of ink jet aptitude>
(Evaluation of print density)
The test paper was solid-printed in monochrome and color using an inkjet printer BJC-420J manufactured by Canon Inc. Next, using a reflection densitometer (trade name “Gretag D186”, manufactured by Gretag Macbeth Co., Ltd.), the print density of the print site was measured. The results are shown in Table 1. The larger the value, the better the print density.
(Evaluation of feathering)
Using the same printer as described above, straight lines and characters having a constant line width were printed in monochrome color on the test paper. Subsequently, the bleeding of the printed part was evaluated visually. The results are shown in Table 1. The larger the value, the stronger the feathering.
(Evaluation of bleeding)
Using the same printer as described above, printing was performed on the test paper so that yellow and black were adjacent to each other, and bleeding of the black ink on the yellow printing portion was visually evaluated. The results are shown in Table 1. The larger the value, the stronger the bleeding.

<Evaluation of foaming>
Each of the sizing agent dilutions 1 to 4 was heated to 50 ° C., and immediately after being treated with a home mixer for 2 minutes, the change in liquid level (mm) was measured. The results are shown in Table 1.

<Evaluation of mechanical stability of emulsion>
Using a two-roll laboratory size press apparatus, the sizing agent dilutions 1 to 4 prepared with water having a hardness of 0 ° dH and the sizing agent dilutions 5 to 8 prepared using water having a hardness of 40 ° dH prepared separately. Each of these was circulated for 1 hour, and the occurrence of aggregates and contamination of the two rolls were visually evaluated according to the following criteria. The results are shown in Table 1.
○: Extremely excellent in mechanical stability (no agglomerates can be confirmed and there is no dirt on the roll)
Δ: Excellent mechanical stability (aggregates cannot be confirmed, but the roll is slightly soiled)
X: Mechanical stability is inferior (aggregates are confirmed and the roll is soiled)

<Evaluation of splash of emulsion>
Using a two-roll laboratory size press, the sizing agent dilutions 1 to 4 (hardness 0 ° dH) were circulated under the conditions of a press speed of 120 m / min and a nip pressure of 15 kg / cm, respectively, and immediately below the roll for 5 minutes. Splash was evaluated based on the degree of the coating solution scattered on the placed white paper. The results are shown in Table 1.
○: There is almost no trace of coating liquid splashing.
X: There are many scattered traces of coating liquid.

Claims (14)

A water-soluble polymer (A) obtained by polymerizing a monomer (a) containing an unsaturated basic acid monomer and an unsaturated hydrophobic monomer, an unsaturated basic acid-modified rosin polyhydric alcohol ester ( B), alkyl (C8-36) succinic anhydride alkali salt and / or alkenyl (C8-36) succinic anhydride alkali salt (C), and alkenyl succinic acid modified starch (D) And an emulsion obtained by emulsion polymerization of a monomer (b) containing an unsaturated basic acid monomer and an unsaturated hydrophobic monomer in an aqueous solution containing at least one selected from the group consisting of Surface sizing agent. The papermaking machine according to claim 1, wherein the unsaturated basic acid monomer of the monomer (a) constituting the water-soluble polymer (A) is (meth) acrylic acid and / or a neutralized salt thereof. Surface sizing agent. The unsaturated hydrophobic monomer of the monomer (a) constituting the water-soluble polymer (A) is a styrene and / or a (meth) acrylic acid alkyl ester according to claim 1 or 2. Surface sizing agent for papermaking. The monomer (a) constituting the water-soluble polymer (A) contains 20 to 80% by weight of an unsaturated basic acid monomer and 80 to 20% by weight of an unsaturated hydrophobic monomer. The surface sizing agent for papermaking according to any one of claims 1 to 3. (B) is an unsaturated basic acid component of at least one selected from the group consisting of (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid and neutralized salts thereof, and pentaerythritol is polyvalent. The surface sizing agent for papermaking according to any one of claims 1 to 4, which is an alcohol component. The surface sizing agent for papermaking according to any one of claims 1 to 5, wherein the acid value of (B) is 60 to 400. The surface sizing agent for papermaking according to any one of claims 1 to 6, wherein (C) is an octadecyl succinic anhydride neutralized salt. The surface sizing agent for papermaking according to any one of claims 1 to 7, wherein (D) is dextrin octenyl succinate. The surface sizing agent for papermaking according to any one of claims 1 to 8, wherein the unsaturated basic acid monomer of the monomer (b) is (meth) acrylic acid and / or a neutralized salt thereof. The surface sizing agent for papermaking in any one of Claims 1-9 whose unsaturated hydrophobic monomer of a monomer (b) is styrene and / or (meth) acrylic-acid alkylester. The monomer (b) contains 2 to 20% by weight of an unsaturated basic acid monomer and 98 to 80% by weight of an unsaturated hydrophobic monomer. The surface sizing agent for papermaking as described. The surface sizing agent for papermaking according to any one of claims 1 to 11, wherein the monomer (b) further contains an acrylamide monomer. The surface sizing agent for papermaking according to claim 12, wherein the acrylamide monomer is (meth) acrylamide. A printing paper obtained by coating a paper with the surface sizing agent for papermaking according to any one of claims 1 to 13.