JP3028308B1 - Surface sizing agent and method for producing the same - Google Patents

Abstract

The present invention provides a surface sizing agent having good mechanical stability and storage stability, low foaming property, and excellent inkjet suitability, and a method for producing the same. A surface sizing agent obtained by polymerizing a nonionic hydrophilic monomer, a hydrophobic monomer and, if necessary, an anionic monomer in the presence of an alkali salt of shellac, and a method for producing the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a surface sizing agent and a method for producing the same, and more particularly, to mechanical stability,
Storage stability, size performance from acid paper to neutral paper,
The present invention relates to a paper-making surface sizing agent having excellent suitability for information paper, low foaming property in a coating solution, and excellent compatibility with other concomitant chemicals, and a method for producing the same.

[0002]

Conventional surface sizing agents for papermaking include styrene-maleic acid copolymers, styrene- (meth) acrylic acid copolymers, and α-olefin-maleic acid copolymers. Aqueous solutions of metal salts are known.

[0003] A styrene-maleic acid copolymer surface sizing agent can exhibit a good sizing effect on paper of an acidic paper making use of a large amount of a sulfuric acid band. Slightly poor sizing performance is obtained with a small amount of neutral paper.

[0004] In addition, when the surface is coated, since the sizing agent itself often foams, it is necessary to use a large amount of the antifoaming agent. As a result, cissing occurs on the coated surface and the sizing effect is deteriorated. There's a problem.

A styrene- (meth) acrylic acid-based copolymer surface sizing agent can express relatively good Steckigt sizing degree with respect to the above-mentioned neutral papermaking paper, but is inferior in pen writing sizing degree. However, there is a problem that characters are blurred at the time of writing.

[0006] In addition, the stability of the coating solution to metal ions is extremely poor, and there are many operational problems such as generation of agglomerates (referred to as "cake" in the field) and foaming.

[0007] The surface sizing agent of the α-olefin-maleic acid copolymer exhibits good pen writing size,
When used for PC paper, the fixability of the toner is low, and when used for printing paper, there is a problem in ink adhesion, and there are operational problems such as a large amount of foaming in the coating liquid.

Further, several patents for emulsion-type surface sizing agents by emulsion polymerization have already been reported as prior art.

For example, Japanese Patent Application Laid-Open No. Hei 8-246391 discloses that
"[B] In an aqueous solution containing 100 parts by weight of a water-soluble copolymer containing (1) a carboxyl group-containing unsaturated monomer and (2) a hydrophobic unsaturated monomer, [A] A papermaking surface sizing agent comprising an emulsion obtained by emulsion polymerization of 10 to 500 parts by weight of an unsaturated monomer "is disclosed.

The particle-type surface sizing agent has a higher compatibility with other concomitant chemicals and a higher stability to dissolved metal ions in the coating solution or a lower coating solution in comparison with the conventional solution-type surface sizing agent. Foamability is improved, but size performance is still inadequate.

Further, Japanese Patent Application Laid-Open No. 49-50209 discloses that at least one monomer selected from styrene and a styrene derivative is contained in an aqueous alkali solution of shellac.
Alternatively, a paper surface treating agent comprising an aqueous dispersion obtained by mixing other monomers copolymerizable therewith, if necessary, and adding a radical polymerization catalyst to the mixture, is disclosed.

However, the surface treating agent is obtained by emulsion-polymerizing styrene and a styrene derivative in an aqueous ammonia solution of shellac, and can improve the water resistance and glossiness of paper, but often generates aggregates during emulsion polymerization. Etc., and the water resistance is insufficient. In addition, the obtained surface treating agent is extremely poor in stability against metal ions and mechanical stability, so that there is a problem in operation on an actual machine.

[0013] More recently, not only ink-jet specialty papers but also PPC papers have been required to have ink-jet suitability, and sizing agents capable of obtaining paper satisfying the suitability have been desired.

The suitability for ink-jet includes characteristics such as print density, feathering, strike-through, and boundary bleeding required for image quality printed by an ink-jet method using monochrome or color ink.

[0015]

DISCLOSURE OF THE INVENTION The present invention provides excellent sizing agents having excellent mechanical stability and storage stability, excellent sizing performance from acidic paper to neutral paper, and information paper, especially ink-jet paper. An object of the present invention is to provide a paper-making surface sizing agent which has excellent inkjet suitability, has extremely low foamability in a coating liquid, and has excellent compatibility with other concomitant chemicals.

[0016]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, in the presence of an alkali salt of shellac, a hydrophobic monomer and a nonionic hydrophilic monomer or a hydrophobic monomer were used. By polymerizing a monomer composed of a monomer, a nonionic hydrophilic monomer and an anionic monomer, a paper-making surface sizing agent capable of overcoming the above problem has been completed.

That is, a first aspect of the present invention is a surface sizing agent obtained by polymerizing a nonionic hydrophilic monomer (b) and a hydrophobic monomer (d) in the presence of an alkali salt of shellac (a). A second aspect of the present invention is to polymerize a nonionic hydrophilic monomer (b), an anionic monomer (c) and a hydrophobic monomer (d) in the presence of an alkali salt of shellac (a). The third aspect of the present invention is to polymerize a nonionic hydrophilic monomer (b) and a hydrophobic monomer (d) in the presence of an alkali salt of shellac (a). A method for producing a surface sizing agent characterized by the following:
The aspect of the present invention is the method for producing a surface sizing agent according to the third aspect, in which a surfactant other than an alkali salt of shellac is present at the time of polymerization.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The surface sizing agent according to the present invention is an emulsion type surface sizing agent. This surface sizing agent
In the presence of the alkali salt of shellac (a) and, if necessary, in the presence of a surfactant other than the alkali salt of shellac, the nonionic hydrophilic monomer (b) and hydrophobic monomer (d), or nonionic It can be obtained by polymerizing a hydrophilic monomer (b), an anionic monomer (c) and a hydrophobic monomer (d).

The shellac used in the present invention is obtained by purifying a resinous substance secreted by lac shell worms parasitic on a southern plant, and is composed of a mixture of many resin acids, for example, aleuritic acid and jaralic acid or It is composed of a softening resin in which laxialalic acid is ester-bonded and a resin in which several softening resins are bonded.

The alkali salt of shellac (a) of the present invention is obtained by neutralizing shellac with an alkali substance.

The alkaline substance used for obtaining the alkali salt of shellac of the present invention may be any substance which can substantially convert shellac into an aqueous solution, and is not particularly limited, but is preferably caustic potash, caustic soda and ammonia. The amount of the alkali substance used is preferably equal to or more than the acid value of shellac in view of stability during emulsion polymerization and stability of the obtained surface sizing agent.

In the present invention, when an alkali salt of shellac is present at the time of polymerization, there is an advantage that the polymerization proceeds slowly, and particularly, fine particles can be obtained at the time of emulsion polymerization.
The resulting surface sizing agent itself has excellent stability, and further has a tendency to improve water resistance and reduce foaming.

The polymerization can be carried out in the presence of a substance having another surface active function in combination with the alkali salt of shellac. As the substance having a surface active function, a known emulsifier or dispersant can be used, and examples thereof include a low molecular surfactant, a surfactant having a polymerizable group, and a polymer dispersant.

As the low molecular surfactant, those which can be generally applied to emulsion polymerization can be used, and nonionic, anionic, amphoteric and cationic low molecular surfactants can be used.

Examples of the nonionic low molecular surfactant include polyoxyalkylene alkyl phenyl ether,
Polyoxyalkylene alkyl ether, polyoxyalkylene fatty acid ester, polyoxypropylene polyoxyethylene glycol glycerin fatty acid ester, sorbitan fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid ester, sucrose fatty acid ester, pentaerythritol fatty acid ester, propylene Glycol fatty acid esters,
Fatty acid diethanolamide, polyoxypropylene polyoxyethylene glycol and the like.

In the present invention, one kind of the nonionic low molecular surfactant may be used alone, or two or more kinds thereof may be used in combination.

The anionic surfactants include phosphate salts such as polyoxyalkylene alkyl phenyl ethers, polyoxyalkylene mono- and distyryl phenyl ethers, polyoxyalkylene alkyl ethers and polyoxyalkylene fatty acid esters, sulfonates, and the like. And succinic acid ester salts and sulfosuccinic acid ester salts, as well as alkali salts of alkylbenzene sulfonic acid salts, naphthalene sulfonic acid formalin condensates, alkenyl succinic acid salts, alkali metal salts of rosin, and alkali metal salts of fortified rosin.

In the present invention, one kind of the above-mentioned anionic low molecular weight surfactants can be used alone, or two or more kinds thereof can be used in combination.

Examples of the cationic surfactant include tetraalkylammonium chloride, trialkylbenzylammonium chloride, alkylamine, mono- and polyoxyethylene alkylamine, and the like.

In the present invention, one kind of the above cationic low molecular surfactants may be used alone, or two or more kinds thereof may be used in combination.

The surfactant having a polymerizable group is generally called a reactive emulsifier and is a compound having a hydrophobic group, a hydrophilic group and a carbon-carbon double bond in a molecule.

The carbon-carbon double bond is, for example, (meth)
It includes a functional group having a double bond such as an allyl group, a 1-propenyl group, a 2-methyl-1-propenyl group, an isopropenyl group, a vinyl group, and a (meth) acryloyl group.

As these surfactants having a polymerizable group, those which can be generally applied to emulsion polymerization can be used, and they are not particularly limited. As a specific example, one of the above functional groups is contained in a molecule. Polyoxyalkylene alkyl ethers, polyoxyalkylene aralkyl ethers, polyoxyalkylene phenyl ethers, polyoxyalkylene mono- and distyryl phenyl ethers and the like, and sulfonates, sulfates, phosphates, and sulfosuccinates thereof. An aliphatic or aromatic carboxylate of a polyoxyalkylene alkyl ether or polyoxyalkylene phenyl ether having at least one functional group in a molecule, an acidic phosphoric acid (meth) acrylate compound, rosin-glycidyl (meth) ) Ack relay Compounds, further, alkyl diphenyl ether disulfonic acid compounds such as hexyl diphenyl ether disulfonic acid, decyl diphenyl ether disulfonic acid, dodecyl diphenyl ether disulfonic acid, hexadecyl diphenyl ether disulfonic acid, and alkali metal salts and ammonium salts such as sodium salts and potassium salts thereof. Can be exemplified.

In the present invention, one kind of the surfactant having a polymerizable group may be used alone, or two or more kinds thereof may be used in combination.

The polymer dispersant is not particularly limited, but basically a synthetic polymer having a hydrophobic group, a nonionic group and / or an ionic group or a general natural polymer dispersant can be used. As an example of a synthetic polymer, polyvinyl alcohol and its modified product, anionic styrene-
Partly or completely saponified (meth) acrylic acid copolymers, anionic or cationic (meth) acrylic ester copolymers or (meth) acrylamide copolymers can be exemplified. Examples of the natural polymer emulsifier include cellulose derivatives such as casein, lecithin and hydroxyethyl cellulose, starch and modified starch.

In the present invention, one kind of the above-mentioned polymer dispersants may be used alone, or two or more kinds thereof may be used in combination.

In the present invention, at least one selected from the group consisting of the above-mentioned low molecular surfactant, surfactant having a polymerizable group, and high molecular dispersant can be used. As the low molecular surfactant, a nonionic low molecular surfactant and an anionic low molecular surfactant are preferable from the viewpoint of the stability of the emulsion.

Among the above surfactants, a surfactant having a polymerizable group and a polymer dispersant are particularly preferable since a surface sizing agent having excellent low foaming properties can be obtained.

The surfactant can be used in the range of 1% by weight to 30% by weight based on the alkali salt of shellac.

In the present invention, when the nonionic hydrophilic monomer (b) is used as the polymerization component, there is an advantage that the production of aggregates formed as a by-product during the emulsion polymerization is suppressed, and the production becomes easy, which is advantageous. The storage stability, the stability to metal ions, and the mechanical stability of the surface sizing agent are also advantageously provided.

The nonionic hydrophilic monomer (b) used in the present invention is a polymerizable monomer having neither a cationic group nor an anionic group but a hydrophilic group.
Acrylamide, acrylonitrile and the like can be mentioned. In the present invention, one type of nonionic hydrophilic monomer can be used alone, or two or more types can be used in combination. From another viewpoint, the nonionic hydrophilic monomer (b) used in the present invention contains a nonionic water-soluble monomer. In any case, among various nonionic hydrophilic monomers, acrylamide which is inexpensive and easily available is preferable.

In the present invention, when the hydrophobic monomer (d) is used as a polymerization component, the resulting surface sizing agent has good water resistance.

The hydrophobic monomer (d) used in the present invention is:
Contains water-insoluble monomers. Examples of the hydrophobic monomer include styrene, styrene derivatives such as α-methylstyrene, vinyltoluene, divinylbenzene, alkyl (meth) acrylate, cyclic alkyl (meth) acrylate, dialkyl diesters of maleic acid and fumaric acid, carbon Vinyl esters such as vinyl tertiary carboxylate and vinyl propionate of several 5 to 10, N-alkyl (meth) acrylamides, methyl vinyl ether, and the like. One of these various hydrophobic monomers can be used alone, or two or more of them can be used in combination. When an alkyl (meth) acrylate and another hydrophobic monomer are used, the amount of the alkyl (meth) acrylate is at least 25% based on the total amount of the hydrophobic monomer.
%, Preferably 40 to 100% by weight in terms of size performance.

In the present invention, an anionic monomer
When (c) is used as a polymerization component, there is an advantage that the stability during emulsion polymerization is further improved, the mechanical stability of the obtained surface sizing agent is further improved, and the adhesion to the base paper is further improved.

The anionic monomer (c) used in the present invention
Is a monomer having an anionic group, for example, a monomer having a carboxylic acid group such as (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, vinyl sulfonic acid, (meth) allyl sulfone Examples thereof include monomers having a sulfonic acid group such as acid, 2-acrylamido-2-methylpropanesulfonic acid and sulfonated styrene, and monomers having a phosphoric ester group such as a phosphoric acid ester of hydroxyalkyl (meth) acrylate. One of these anionic monomers can be used alone, or two or more of them can be used in combination. Of these, anionic monomers having a carboxyl group are preferred because they impart low foaming properties to the surface sizing agent, and (meth) acrylic acid and itaconic acid are particularly preferred.

The combination of the above monomer components includes a combination of a nonionic hydrophilic monomer (b) and a hydrophobic monomer (d), and a combination of a nonionic hydrophilic monomer (b) and an anionic monomer (c). Combinations with the hydrophobic monomer (d) can be mentioned. The object of the present invention can be achieved by employing a combination of the nonionic hydrophilic monomer (b) and the hydrophobic monomer (d), and further, the nonionic hydrophilic monomer (b) and the anionic monomer ( When a combination of c) and the hydrophobic monomer (d) is employed, it is possible to obtain a surface sizing agent excellent in that the mechanical stability is further improved and the adhesion to the base paper is further improved.

The amounts of the alkali salts of shellac (a), the nonionic hydrophilic monomer (b), the anionic monomer (c) and the hydrophobic monomer (d) used in the production of the surface sizing agent of the present invention are as follows: Hydrophobic monomer (d) 100
1 to 20 parts by weight of an alkali salt of shellac (a), 1 to 20 parts by weight of a nonionic hydrophilic monomer (b) and 0.1 to 10 parts by weight of an anionic monomer (c) based on parts by weight. The surface sizing agent is preferred from the viewpoint of stability and sizing performance, and particularly preferred is the hydrophobic monomer (d) 10
5 parts by weight of alkali salt of shellac (a)
Parts by weight, 5 to 15 parts by weight of the nonionic hydrophilic monomer (b) and 0.5 to 5 parts by weight of the anionic monomer (c).

In producing the surface sizing agent of the present invention, a conventionally known polymerization method can be applied, and a solution polymerization method, a bulk polymerization method, an emulsion polymerization method and the like can be applied. preferable. In this case, substantially all of the monomers are polymerized to form a homopolymer or a copolymer, and shellac is also considered to be involved in the polymerization.

Examples of the radical polymerization catalyst used in the above polymerization method include ammonium persulfate, potassium persulfate,
Persulfates such as sodium persulfate, peroxides such as tertiary butyl hydroperoxide, redox polymerization catalysts using a combination of these persulfates or peroxide and a reducing agent, or 2,2′-azobisisobutyric acid Examples thereof include azo catalysts such as lonitrile and 2,2′-azobis-2-methylpropionamidine dihydrochloride.
If necessary, a known chain transfer agent may be appropriately used in combination.

The pulp used for the base paper to which the surface sizing agent of the present invention is applied may be bleached or unbleached chemical pulp such as kraft pulp or sulfite pulp, bleached chemical pulp, mechanical pulp or thermomechanical pulp. Examples include unbleached high-yield pulp, waste paper pulp such as waste newspaper, magazine waste, corrugated waste paper, and deinked waste paper.

In order to obtain base paper, fillers, dyes, rosin-based sizing agents for acid papermaking, alkylketene dimer-based or alkenylsuccinic anhydride-based sizing agents for neutral papermaking, rosin-based sizing agents for neutral papermaking, etc. Additives such as a dry paper strength enhancer, a wet strength enhancer, a retention improver, a drainage improver, and an antifoaming agent are also used as needed to develop the physical properties required for each paper type. May be used. Fillers include clay, talc, titanium oxide, heavy or light calcium carbonate, and the like. These may be used alone or in combination.

Examples of a coating machine for coating the surface sizing agent of the present invention include a size press, a film press, a gate roll coater, a simsizer, a blade coater, a calender, a bar coater, a knife coater, an air knife coater, and a curtain. A coater or the like can be used. Further, it can be applied to the base paper surface by a spray coater.

When applying the surface sizing agent of the present invention, starches such as oxidized starch, phosphorylated esterified starch, enzyme-modified starch and cationized starch, celluloses such as carboxymethylcellulose, polyvinyl alcohols and polyacrylamides Alternatively, a water-soluble polymer such as sodium alginate can be mixed with the coating solution before use. Also, other surface sizing agents, anti-slip agents, preservatives, rust inhibitors, defoamers, viscosity modifiers,
Additives such as dyes and pigments may be used in combination.

Examples of the sizing paper obtainable by applying the surface sizing agent of the present invention to the base paper include various papers and paperboards. For example, PPC paper,
Recording paper such as inkjet recording paper, laser printer paper, foam paper, thermal transfer paper, thermal recording paper,
Coated paper such as art paper, cast coated paper, high quality coated paper, kraft paper, wrapping paper such as pure white roll paper, other note paper, book paper, printing paper, newspaper paper and other Western paper, manila balls, white balls, chip balls Paperboard for paper containers, etc.
Paperboard such as a liner is included.

The concentration of the surface sizing agent in the coating solution used when applying the surface sizing agent of the present invention is usually 0.1 to 10%.
It is 5% by weight, preferably 0.2-1% by weight. 0.1
If it is less than the weight%, the size effect may be insufficient,
Use of more than 5% by weight is not preferable because there is almost no improvement in size effect and it is economically disadvantageous.

Usually, the coating amount is 0.01 in terms of solid content.
１1 g / m ² , preferably 0.02 to 0.1 g / m ² . When it is within the above range, the size effect is particularly well exhibited.

[0057]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

(Synthesis Example 1) An ammonium aqueous solution of a styrene-acrylic acid copolymer, that is, a polymer dispersant (S-1), according to Reference Example 2 of JP-A-8-246391.
Was synthesized as follows.

In a 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet, 100 liters of water was placed.
And 75 parts of 95% isopropyl alcohol, and the mixture was heated with stirring to raise the temperature to 80 ° C. To this, a monomer mixture obtained by mixing 45 parts of styrene and 55 parts of acrylic acid, and a polymerization initiator solution obtained by dissolving 5 parts of potassium persulfate in 120 parts of water were dropped in 3 hours, and then 2 hours. After aging, the reaction was completed. Thereafter, isopropyl alcohol was distilled off, and after cooling, 46.4 parts of a 28% aqueous ammonia solution (100 mol% based on acrylic acid) was added, and the mixture was diluted with water to prepare a copolymer having a concentration of 20%. Then, an ammonium aqueous solution of a styrene-acrylic acid copolymer as a water-soluble copolymer, that is, a polymer dispersant (S-1) was obtained.

Example 1 748 parts of water and shellac (N81 manufactured by Gifu Shellac Co., Ltd.) were placed in a 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube.
1) 20.2 parts (10% by weight), acrylamide
2 parts (10% by weight based on 100% by weight of a hydrophobic monomer) and 4.3 parts of potassium hydroxide were added.
Parts (50% by weight), normal butyl acrylate 101
Part (50% by weight) and an aqueous solution of ammonium persulfate in an amount of 0.
6 parts were added, and the mixture was heated to 80 ° C. while mixing and stirring under a nitrogen stream.

The emulsion polymerization reaction was completed by holding at 80 ° C. for 2 hours to obtain an emulsion-type surface sizing agent having a solid content of 25.1%.

(Examples 2 to 10, Comparative Examples 1 and 2) The types and amounts of alkali salts of shellac, nonionic hydrophilic monomers and anionic monomers, and the types and amounts of hydrophobic monomers were changed as shown in Table 1. Except for the above, an emulsion-type surface sizing agent was obtained in the same manner as in Example 1.

Comparative Example 3 In a reactor similar to that of Synthesis Example 1, 275 parts of water and 100 parts of an aqueous ammonium solution of a styrene-acrylic acid copolymer of Synthesis Example S-1 (solid content: 20 parts)
Parts), 50 parts of styrene, normal butyl acrylate 5
0 parts and 5 parts by weight of a 10% ammonium persulfate aqueous solution were added, and the mixture was heated to 80 ° C. while mixing and stirring under a nitrogen stream.

The emulsion polymerization reaction was completed by holding at 80 ° C. for 2 hours to obtain a comparative surface sizing agent having a solid content of 25%.

Comparative Example 4 As Comparative Example 4, a commercially available styrene-acrylic surface sizing agent SS315 (manufactured by PMC Japan) was used.

(Test Example 1) Evaluation on acidic high-quality paper (1) Production of base paper for acidic high-quality paper Pulp beaten to 380 ml Canadian Standard Freeness (pulp ratio of hardwood to softwood is 9: 1)
(Mixed pulp) was made into a 2.5% slurry, and talc (manufactured by Fuji Talc Kogyo: ND talc) with a pulp content of 15% (on a dry basis) was added to the slurry. In addition, pulp 2
% (Based on absolute dry weight) sulfuric acid band, 0.3% based on pulp
Rosin sizing agent for acid paper (based on absolute dry weight) (Japan P
MC; AL120) was sequentially added, and the pulp slurry was diluted to a concentration of 0.25% with dilution water having a pH of 4.5. Thereafter, a retention improver (NR12MLS, manufactured by Hymo Co., Ltd.) of 0.01% with respect to pulp was added, and the paper was made with a Noble and Wood paper machine so as to have a basis weight of 65 g / m ² . The papermaking pH at this time was 4.5. Drying of the wet paper was performed using a drum dryer at 100 ° C. for 80 seconds.

(2) Method for Preparing Coating Solution Oxidized starch (MS3800 manufactured by Nippon Shokuhin Kako Co., Ltd.) at a concentration of 1
The solution was diluted to 0% with water, gelatinized at 95 ° C., and a coating solution was prepared so as to have the following solid content concentration. The pH of the coating solution was adjusted to pH 8 with caustic soda or pH 6 with sulfuric acid. .

As the solid content concentration of the coating liquid, oxidized starch was 6%.
% And the surface sizing agent were 0.2%.

(3) Production and Evaluation of Acid Fine Paper The base paper made in the above (1) was coated with the coating solution mixed in the above (2) by a size press to obtain an acidic fine paper.
The obtained test paper is kept at a constant temperature and humidity (20 ° C., 65% relative humidity).
Conditioning for 24 hours in an environment, the degree of Sekikichito size (JIS
P8122) and measurement of pen writing size (J
TAPPI paper pulp test method No. 12-76).

Table 2 shows the evaluation results. It should be noted that the higher the value of both the Steckigt sizing degree and the pen writing sizing degree, the better.

Test Example 2 Evaluation with Neutral Fine Paper (1) Papermaking of Neutral Fine Base Paper Pulp beaten to 380 ml Canadian Standard Freeness (pulp ratio of hardwood to softwood is 9: 1)
(Mixed pulp) was made into a 2.5% slurry, and calcium carbonate (TP121S, manufactured by Okutama Kogyo Co., Ltd.) of 2% (based on absolute dry weight) based on pulp was added to this slurry. In addition, an amphoteric starch (manufactured by National Starch; Cato3210) having a pulp content of 0.5% (based on absolute dry weight) and an alkyl ketene dimer-based sizing agent (manufactured by Nippon PMC) having a pulp content of 0.08% (based on absolute dry weight) AS263) was added successively, and then this pulp slurry was diluted to a concentration of 0.25% with dilution water having a pH of 7.5. Then, the diluted pulp slurry was made of calcium carbonate (TP121S, manufactured by Okutama Kogyo Co., Ltd.) of 8% (based on absolute dry weight) based on pulp, and 0.0 based on pulp.
1% retention aid (HIMO; NR12MLS) was added, and the basis weight was 65 g /
The paper was made to have m ² . The papermaking pH at this time was 7.5. Drying of the wet paper was performed using a drum dryer at 100 ° C. for 80 seconds.

(2) Preparation method of coating liquid Oxidized starch (MS3800 manufactured by Nippon Shokuhin Kako Co., Ltd.)
The solution was diluted to 0% with water, gelatinized at 95 ° C., and a coating solution was prepared so as to have the following solid concentration, and the pH of the coating solution was adjusted to pH 8 with sodium hydroxide.

Solid content concentration of coating liquid: oxidized starch 6% Surface sizing agent 0.2% (3) Production and evaluation of neutral high-quality paper The base paper made in (1) was blended in (2). p
The coating liquid of H8 was applied using a size press to obtain a neutral high-quality paper. The obtained test paper was subjected to constant temperature and humidity (20 ° C., 65%
(Relative humidity) The humidity was adjusted for 24 hours in an environment, and the measurement of the Stigecht sizing degree and the pen writing sizing degree was performed in the same manner as in Test Example 1. Table 2 shows the results.

(Test Example 3) Evaluation on Inkjet Recording Paper (1) Production of Neutral Base Paper for Recording Paper Pulp beaten to 380 ml Canadian Standard Freeness (pulp ratio of hardwood to softwood is 9: 1)
Is mixed with 2.5% slurry, and calcium carbonate (TP121S manufactured by Okutama Kogyo Co., Ltd.) and 5% talc (Fuji Talc Kogyo Co., Ltd .: ND) Talc) was added. A sulfate band of 1.0% (based on absolute dry weight) based on pulp, an amphoteric starch (manufactured by National Starch; Cato3210) of 0.5% (based on absolute dry weight) and a pulp of 0.3% based on pulp were used.
% (Based on absolute dry weight) of a rosin-based sizing agent for neutral paper (manufactured by Nippon PMC; CC167), and then added at pH 7.0.
This pulp slurry was diluted with a dilution water of 5 to a concentration of 0.25%. Thereafter, calcium carbonate (TP121S, manufactured by Okutama Kogyo Co., Ltd.) and pulp (0.01%) were added to the diluted pulp slurry by adding 4% (based on absolute dry weight) of calcium carbonate to pulp (NR12MLS). Paper was made with a Noble and Wood paper machine to a basis weight of 65 g / m ² . The papermaking pH at this time was 7.5. Dry the wet paper at 100 ° C. using a drum dryer at 80 ° C.
The test was performed under the condition of seconds.

(2) Preparation method of coating solution Oxidized starch (MS3800 manufactured by Nippon Shokuhin Kako Co., Ltd.)
The solution was diluted to 0% with water, gelatinized at 95 ° C., and a coating solution was prepared so as to have the following solid concentration, and the pH of the coating solution was adjusted to pH 8 with sodium hydroxide.

As the solid content concentration of the coating solution, oxidized starch was 8%.
%, The surface sizing agent was 0.2%, and the salt was 0.25%.

(3) Production of Recording Paper The coating liquid mixed in (2) was applied to the recording base paper made in (1) using a size press to obtain a recording paper. The obtained test paper was conditioned for 24 hours under a constant temperature and constant humidity (20 ° C., 65% relative humidity) environment.

(4) Evaluation of Recording Paper The test paper obtained in the above (3) was subjected to constant temperature and humidity (20 ° C., 65
% Relative humidity) in an environment for 24 hours, and the following inkjet suitability test was performed.

(Test Method for Ink-Jet Suitability) Evaluation of ink-jet suitability was carried out by subjecting the test paper obtained in the size effect test to a calender treatment, and then to constant temperature and humidity (20 ° C., 65 ° C.).
% Relative humidity) under an environment for 24 hours or more, and then a BJ-Bubble Jet Printer manufactured by Canon Inc.
This was performed using 220JCII by the following method. Table 3 shows the results.

(A) Print Density Test Solid printing was performed on test paper, and the print density of the solid portion was measured with a Macbeth ink densitometer. The higher the value, the higher the print density.

(B) Feathering Test A straight line and a character having a constant line width perpendicular to the test paper were printed, and the bleeding of the outer edge of the straight line and the character was visually evaluated on a five-point scale. The sample having no feathering was designated as 5, and the sample having ink bleeding and the characters could not be identified was designated as 1.
The print quality that can withstand normal use is 4 or more.

(C) Run-through test Solid printing was performed on a test paper, and the degree of bleeding of the ink on the back side of the solid printing portion was visually evaluated on a scale of 5 levels. The sample with no ink bleeding on the back was designated as 5, and the sample with the solid portion completely penetrated was designated as 1. The print quality that can withstand normal use is 4 or more.

(Test Example 4) Foamability test (1) Preparation of test solution for foamability evaluation Oxidized starch (MS3800 manufactured by Nippon Shokuhin Kako Co., Ltd.) at a concentration of 1
The mixture was diluted to 0% with water, gelatinized at 95 ° C., and a coating liquid was prepared so as to have the following solid content concentration.

As the solid content concentration of the coating solution, oxidized starch was 5%.
%, The surface sizing agent was 0.2%, and the salt was 0.25%.

(2) Evaluation of foaming property of coating liquid 600 g of the coating liquid mixed in the above (1) was placed in a foam cell having an inner diameter of 7 cm and a length of 50 cm, and circulated under the following conditions to obtain a foam height ( mm). Table 3 shows the results.

The coating liquid temperature was 60 ° C., the circulation pump flow rate was 9 liters / minute, and the circulation time was 3 minutes. In Table 3, the lower the foam height, the lower the foaming property (the smaller the foaming amount).

(Test Example 5) Mechanical Stability Test 50 g of the coating liquid prepared in the above (1) was placed in a cup, and heated at a temperature of 60 ° C., a load of 20 kg, and a rotation speed of 800 rpm.
A Marlon stability test was performed for one minute. The formed aggregate was filtered through a 325 mesh wire net, and the amount of the precipitate relative to the total solid content was measured and expressed as a percentage. Table 3 shows the results.

(Test Example 6) Stability test for metal ions Changes in the state of the dispersion liquid when the surface sizing agent was diluted to 0.3% in solid content using diluted water having a hardness of 500 ppm (as CaCO ₃ ). Indicates that no odor was observed, △ indicates that turbidity was slightly observed, and × indicates that a precipitate was observed. Table 3 shows the results.

From the evaluation results of the acidic high-quality paper and the neutral high-quality paper in Table 2, the surface sizing agents of the examples had little effect on the change in the pH of the coating solution, and the sizing and pens sizes were compared. It was found to be better than the surface sizing agent of the example.

From the evaluation results of the ink jet recording papers shown in Table 3, it was found that the surface sizing agents of the examples had better print density, feathering and strikethrough evaluations than the surface sizing agents of the comparative example.

From the evaluation results shown in Table 3, the foaming property of the surface sizing agent of the example was lower than that of the comparative example, and the mechanical stability and the stability to metal ions were lower than those of the surface sizing agent of the example. It was found to be superior to the surface sizing agent of the comparative example.

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[Table 1]

St Styrene IBMA Isobutyl methacrylate BA Butyl acrylate AAm Acrylamide NBMA Normal butyl methacrylate MAA Methacrylic acid EHMA Ethylhexyl methacrylate IA Itaconic acid MS-60 Antox MS-60 (Reactive emulsifier, manufactured by Nippon Emulsifier Co.)

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[Table 2]

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[Table 3]

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Industrial Applicability The surface sizing agent of the present invention is excellent in mechanical stability, low foaming property and storage stability, can improve the sizing performance of acidic paper to neutral paper, and can improve information paper,
In particular, it has excellent suitability for ink-jet paper, low foaming properties in a coating liquid, compatibility with other concomitant chemicals, and excellent stability against dissolved metal ions.

Claims (4)

(57) [Claims] A surface sizing agent obtained by polymerizing a nonionic hydrophilic monomer (b) and a hydrophobic monomer (d) in the presence of an alkali salt of shellac (a). 2. A surface sizing agent obtained by polymerizing a nonionic hydrophilic monomer (b), an anionic monomer (c) and a hydrophobic monomer (d) in the presence of an alkali salt of shellac (a). 3. A method for producing a surface sizing agent, comprising polymerizing a nonionic hydrophilic monomer (b) and a hydrophobic monomer (d) in the presence of an alkali salt of shellac (a). 4. The method for producing a surface sizing agent according to claim 3, wherein a surfactant other than an alkali salt of shellac is present during polymerization.