JPH10280294A - Particulate surface-sizing agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject sizing agent for paper-making use having excellent sizing performance for acidic paper and neutral paper and suitable for ink-jet printing by the emulsion polymerization of a hydrophobic monomer in the presence of a specific (meth)acrylamide copolymer. SOLUTION: A hydrophobic monomer is polymerized by emulsion polymerization using an emulsifying and dispersing agent consisting of a (meth)acrylamide copolymer copolymerized with >=68 mol% of (meth)acrylamide. The hydrophobic monomer may be mixed with 0.1-30 wt.% (based on the total monomer) of an anionic monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a particle-type surface sizing agent, and more particularly to a particle-type surface sizing agent for papermaking obtained by emulsion polymerization using a specific emulsifying dispersant.

[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. In addition, when the surface is coated, the sizing agent itself often foams, so that a large amount of antifoaming agent is required.

A styrene- (meth) acrylic acid 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.

[0005] In addition, the stability of the coating solution to metal ions is extremely poor, and there are many operational problems such as generation of cake and foaming.

The surface sizing agent of the α-olefin-maleic acid copolymer shows a 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.

Several patents have already been reported as prior art as particle type (emulsion type) surface sizing agents which carry out emulsion polymerization in the presence of a polymeric emulsifier.

For example, Japanese Patent Application Laid-Open No. 8-246391 discloses that
"(A) 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 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 than the conventional solution-type surface sizing agent. Although the foamability is improved, its effect is still insufficient.

Further, Japanese Patent Application Laid-Open No. 8-158292 discloses that "acrylamide polymer having an anionic group (A), hydrophobic vinyl monomer (b ₁ ), anionic vinyl monomer and / or its salt (b) ₂ ) contains a copolymer (B) obtained by polymerization as an essential component, and has a compounding weight ratio of (A) :( B) = 100: 0.1 to
And a surface paper quality improver characterized by being 100. "

However, the surface modifier is a mixture of an anionic polyacrylamide conventionally used as a surface strengthening agent at the time of coating and a styrene-methacrylic acid type aqueous solution conventionally used as a surface sizing agent. By selecting the mixing ratio, the paper surface properties such as size, ink receptivity and smoothness are improved, and stability against dissolved metal ions in the coating liquid and low foaming property in the coating liquid are not improved. It is enough.

[0012] More recently, PPC paper as well as paper for exclusive use of ink jet have been required to have ink jet suitability, and a sizing agent capable of obtaining paper satisfying the suitability has 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.

[0014]

DISCLOSURE OF THE INVENTION The present invention is excellent in mechanical stability, low foaming property and storage stability of a sizing agent itself. It can be improved and has excellent ink jet suitability for information paper, especially ink jet paper, and has low foaming property in coating liquid, compatibility with other concomitant chemicals, and stable against dissolved metal ions. An object of the present invention is to provide a paper sizing agent for papermaking.

[0015]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that, in the presence of a (meth) acrylamide-based copolymer containing (meth) acrylamide as a main component, The present invention has completed a papermaking surface sizing agent capable of overcoming the above-mentioned problems by emulsion-polymerizing a hydrophilic vinyl monomer alone or a hydrophobic vinyl monomer and an anionic monomer.

That is, a first aspect of the present invention provides a method for producing a (meth)
The present invention is a particle-type surface sizing agent obtained by emulsion-polymerizing a hydrophobic monomer (b1) in the presence of a (meth) acrylamide-based copolymer [A] composed of at least 68 mol% of acrylamide (a1). The second aspect of
In the presence of a (meth) acrylamide-based copolymer [A] comprising at least 68 mol% of (meth) acrylamide (a1), 70 to 99.9% by weight of a hydrophobic monomer (b1) and 30 to 0.1% by weight % Of the anionic monomer (b2) so that the total weight% of the two components is 100, and is a particle type surface sizing agent obtained by emulsion polymerization of the component (B). In a third embodiment, in the first and second embodiments, the component [A] is 99.9 to
70 mol% of (meth) acrylamide (a1);
(Meth) acrylamide-based copolymer obtained by copolymerizing 1 to 30 mol% of anionic monomer (a2) such that the total mol% of the two components becomes 100. A particle type surface sizing agent,
According to an embodiment, in the particle-type surface sizing agent according to the first or second embodiment, the component [A] is 69.9 to 99.8 mol%.
(Meth) acrylamide (a1), 0.1 to 30 mol% of an anionic monomer (a2), and 0.1 to 20 mol% of another copolymerizable vinyl monomer (a3) A fifth aspect of the present invention is a (meth) acrylamide-based copolymer obtained by copolymerization such that the total mol% of the components becomes 100. The fifth aspect of the present invention is the first aspect or the second aspect. In the particle type surface sizing agent of the embodiment,
The component (A) is a (meth) acrylamide-based copolymer obtained by copolymerizing (meth) acrylamide (a1) in the presence of an alkylmercaptan [C] having 6 to 22 carbon atoms. A sixth aspect of the present invention is the above-mentioned first to third aspects.
In the particle type surface sizing agent according to any one of the above aspects, [A]
The component is composed of 70 to 99.9 mol% of (meth) acrylamide (a1) and 0.1 to 30 mol% of anionic monomer (a2) in the presence of alkyl mercaptan [C] having 6 to 22 carbon atoms. A seventh aspect of the present invention is a particle-type surface sizing agent according to the first or second aspect, wherein the (meth) acrylamide-based copolymer is obtained by copolymerization under the following conditions. The component (A) comprises 69.9 to 99.8 mol% of (meth) acrylamide (a1) and 0.1 to 3
0 mol% of the anionic monomer (a2) and 0.1 to 2
0 mol% of other copolymerizable vinyl monomers (a
3) is a (meth) acrylamide-based copolymer obtained by copolymerizing in the presence of an alkylmercaptan [C] having 6 to 22 carbon atoms. In any one of the first to seventh aspects, the total [B] of the (meth) acrylamide-based copolymer [A], the hydrophobic monomer (b1) and the anionic monomer (b2) Weight ratio of 10 to 50: 1
The ninth aspect of the present invention is the composition according to any one of the fifth to eighth aspects, wherein the monomer component of the (meth) acrylamide copolymer [A] It is characterized in that 0.01 to 2 mol of the alkyl mercaptan [C] is used per 100 mol.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The particle type surface sizing agent of the present invention is a (meth) acrylamide-based copolymer comprising (meth) acrylamide in which the component (A) is at least 68 mol%,
Further, a (meth) acrylamide copolymer obtained by copolymerizing 99.9 to 70 mol% of (meth) acrylamide (a1) and 0.1 to 30 mol% of anionic monomer (a2), or 69.9-99.8 mol% of (meth) acrylamide (a1), 0.1-30 mol% of anionic monomer (a2), and 0.1-30 mol% of other copolymerizable vinyl (Meth) acrylamide copolymer obtained by copolymerizing with monomer (a3), and (meth) obtained by copolymerizing the monomer in the presence of alkyl mercaptan [C] having 6 to 22 carbon atoms It is an acrylamide copolymer.

Here, 68% by mole or more of (meth) acrylamide in the component (A) refers to (meth) acrylamide 6
8 to 100 mol% is used, and the remaining component is to use another copolymerizable monomer.

The (meth) acrylamide (a1) used for producing the component [A] is at least one selected from the group consisting of acrylamide and methacrylamide, and these may be used alone or in combination.

It is preferable to use acrylamide because it is inexpensive and easily available.

The anionic monomer (a2) used for producing the component (A) is a monomer having a carboxylic acid group such as (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid and crotonic acid. Monomers having a sulfonic acid group such as vinyl sulfonic acid, (meth) allyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and sulfonated styrene; and phosphoric ester groups such as a phosphoric acid ester of hydroxyalkyl (meth) acrylate. And among them, a monomer having a carboxyl group is preferable in view of low foaming property.

These can be used alone or in combination of two or more.

The (a3) other copolymerizable vinyl monomer is not particularly limited, but the (meth) (a1)
Any monomer other than acrylamide and the anionic vinyl monomer (a2) can be used as long as it is a monomer copolymerizable with (a1) and (a2). For example, a monomer having a hydrophobic group and a monomer having a cationic group can be used.

Examples of the hydrophobic monomer include styrene, styrene derivatives such as α-methylstyrene, vinyltoluene and divinylbenzene, alkyl (meth) acrylates, cyclic alkyl (meth) acrylates, and dialkyl diesters of maleic acid and fumaric acid. And vinyl esters such as vinyl acetate and vinyl propionate, N-alkyl (meth) acrylamides, and methyl vinyl ether. One or more of these monomers may be used in combination.

Examples of the cationic monomer include, for example,
(Mono- or di-alkyl) aminoalkyl (meth) acrylate, (mono- or di-alkyl) aminohydroxylalkyl (meth) acrylate, (mono- or di-alkyl) aminoalkyl (meth) acrylamide,
Examples thereof include vinylpyridine, vinylimidazole, diallylamine and the like, and furthermore, quaternary ammonium salts thereof, and one or more of these can be used in combination.

The alkyl mercaptan [C] having 6 to 22 carbon atoms used in producing the component [A] is as follows:
The alkyl group may be a linear or branched mercaptan, and the raw material of the alkyl group may be a natural one or an artificially produced one such as cracking of low-polymerized paraffin such as ethylene or propylene. For example, normal-octyl mercaptan, tertiary decyl mercaptan, normal-dodecyl mercaptan, normal-octadecyl mercaptan, normal-hexadecyl mercaptan and the like can be mentioned.
These may be used alone or in combination of two or more. Of these, alkyl mercaptans having 8 to 16 carbon atoms are preferable, and normal-octyl mercaptan and normal-dodecyl mercaptan are particularly preferable. Even if the alkyl mercaptan is used in an amount of 10 mol% or more based on all monomers, the amount of the alkyl mercaptan which is not introduced into the polymer during the polymerization reaction may increase, adversely affecting the size effect, and is not economically preferable.

As a method for synthesizing the (meth) acrylamide copolymer [A], a conventionally known method can be applied.

For example, in the presence or absence of an alkyl mercaptan having 6 to 22 carbon atoms, the monomer (a1) alone, or the monomer (a1) and (a2)
And / or the monomer (a3) in a lower alcohol such as methyl alcohol, ethyl alcohol or isopropyl alcohol, in a mixed solution of these lower alcohols and water, or in water at 60 to 95 ° C. with a radical polymerization catalyst. It is obtained by polymerizing for 1 to 10 hours and distilling off lower alcohol after the polymerization is completed. Examples of the radical polymerization catalyst include persulfates such as ammonium persulfate, potassium persulfate, and sodium persulfate; redox polymerization catalysts obtained by combining these persulfates with a reducing agent; and 2,2′-azobisisobutyronitrile. ,
An azo catalyst such as 2,2'-azobis-2-methylpropionamidine dihydrochloride can be mentioned. If necessary, a known chain transfer agent may be appropriately used in combination. In the present invention, the monomers charged in synthesizing the (meth) acrylamide-based copolymer [A] react substantially 100%, and the monomers in the (meth) acrylamide-based copolymer [A] are reacted. Become a unit.

(Meth) acrylamide copolymer [A]
Of a solution of 10 to 10,000 in a 20% by weight aqueous solution.
A centipoise (however, a value measured at 25 ° C. at 60 revolutions per minute by a Brookfield viscometer) is preferable, and a viscosity of 50 to 5000 centipoise is particularly preferable.

When the composition ratio or the viscosity of the component (A) of the (A) monomer of the (meth) acrylamide copolymer is within the above range, when the monomer (B) is emulsion-polymerized, the aggregation of particles or No thickening (creaming) is caused.

(Meth) acrylamide copolymer [A]
The alkyl mercaptan [C] having 6 to 22 carbon atoms used for synthesizing is for improving the stability at the time of emulsion polymerization, and is usually used in the range of 0.01 to 5 mol%. It is preferably used in the range of 0.01 to 2 mol%, particularly preferably in the range of 0.01 to 1 mol%.

The particle type surface sizing agent of the present invention comprises (meth)
It can be obtained by emulsion polymerization of the hydrophobic vinyl monomer (b1) alone or the hydrophobic vinyl monomer (b1) and the anionic monomer (b2) as the monomer of the component [B] in the presence of the acrylamide copolymer [A]. it can.

(Meth) acrylamide copolymer [A]
Component (B) is preferably 10 to 50 parts by weight based on 100 parts by weight of component [B], from the viewpoint of stability of the emulsion. In particular, it is preferable to contain 15 to 30 parts by weight from the viewpoint of size performance.

Component (B) is a hydrophobic vinyl monomer (b)
When 1) and the anionic vinyl monomer (b2) are contained, the amount of the hydrophobic vinyl monomer (b1) used is at least 70% by weight, preferably 70 to 99.9.
% By weight, and the amount of the anionic vinyl monomer (b2) used is at most 30% by weight, preferably 30 to 30% by weight.
0.1% by weight. The amount of the hydrophobic vinyl monomer (b1) used is at least 80% by weight from the viewpoint of size performance and mechanical stability.
The amount of the anionic vinyl monomer (b2) is preferably at most 20% by weight, particularly preferably in the range of 0.1 to 20% by weight.

As the hydrophobic monomer (b1), the hydrophobic monomer used in the (meth) acrylamide copolymer [A] can be used, and specifically, styrene, α-methylstyrene, vinyltoluene, Styrene derivatives such as divinylbenzene, alkyl (meth) acrylates, dialkyl diesters of maleic acid and fumaric acid, cyclic alkyl (meth) acrylates, vinyl esters such as vinyl acetate and vinyl propionate, N
-Alkyl (meth) acrylamides and methyl vinyl ethers, and one or more of these can also be used.

As the anionic monomer (b2), the anionic monomer used in the (meth) acrylamide-based copolymer [A] can be used. Specifically, (meth) acrylic acid, maleic acid, fumaric acid, Monomers having a carboxylic acid group such as itaconic acid, citraconic acid, crotonic acid, vinylsulfonic acid, (meth) allylsulfonic acid,
-Acrylamide-2-methylpropanesulfonic acid, a monomer having a sulfonic acid group such as sulfonated styrene,
Monomers having a phosphate group such as a phosphate of hydroxyalkyl (meth) acrylate can be mentioned. Among these monomers, (meth) acrylic acid, maleic acid, and fumaric acid are preferable, and (meth) acrylic acid is particularly preferable. Also, one or more of these may be used.

Of these, monomers having a carboxyl group are preferred in view of low foaming properties. These can be used alone or in combination of two or more.

For the emulsion polymerization of the component [B], a conventionally known emulsion polymerization method can be applied. For example, the monomers (b1) and (b2) can be prepared in the presence of the (meth) acrylamide copolymer [A]. Alternatively, a method of emulsion polymerization in water with a radical polymerization catalyst may be employed. In this case, substantially all of the component [B] is polymerized to form a homopolymer or a copolymer.

Examples of the radical polymerization catalyst include persulfates such as ammonium persulfate, potassium persulfate and sodium persulfate, redox polymerization catalysts obtained by combining these persulfates and reducing agents, and 2,2′-azobisisopropane. Azo catalysts such as butyronitrile and 2,2'-azobis-2-methylpropionamidine dihydrochloride can be mentioned. If necessary, a known chain transfer agent may be appropriately used in combination.

In carrying out the emulsion polymerization of the component [B],
Although the amount of the component [A] is not particularly limited, the amount of the component [A] used is usually 10%.
Usually, 10 to 50 parts by weight of solid content is used with respect to 0 parts by weight. When the amount of the component (A) is less than 10 parts by weight,
The diameter of the particles in the obtained particle-type sizing agent is sometimes undesirably large. On the other hand, when the use amount of the component [A] is more than 50 parts by weight, the particle size in the obtained particle type sizing agent is not further reduced. It is not preferable because the agent may foam.

When emulsion polymerization of the monomer of the component (B) is carried out, a known low-molecular surfactant and a high-molecular dispersant may be used in combination as long as the performance of the present particle-type surface sizing agent is not impaired. I do not care.

The pulp used for the base paper to which the particle type surface sizing agent of the present invention is applied includes bleached or unbleached chemical pulp such as kraft pulp or sulfite pulp, groundwood pulp, mechanical pulp or thermomechanical pulp. Bleached or unbleached high yield pulp, used newspaper,
Any used paper pulp such as used magazine paper, used corrugated paper, or used deinked paper can be used.

In order to obtain base paper, fillers, dyes, rosin-based sizing agents for acidic 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 particle size papermaking surface sizing agent of the present invention include a size press, a film press, a gate roll coater, a shim sizer, a blade coater, a calender, a bar coater, a knife coater, and an air coater. A knife coater, a curtain coater, or the like can be used. Further, it can be applied to the base paper surface by a spray coater.

When applying the particle-type surface sizing agent of the present invention, starch such as oxidized starch, phosphorylated esterified starch, self-modified starch, cationized starch, cellulose such as carboxymethyl cellulose, polyvinyl alcohol, polyalcohol, etc. A water-soluble polymer such as acrylamides and sodium alginate can be mixed with the coating solution and used. Further, other additives such as a surface sizing agent, an anti-slip agent, a preservative, a rust inhibitor, an antifoaming agent, a viscosity modifier, a dye and a pigment may be used in combination.

As the sizing paper obtainable by applying the particle type surface sizing agent of the present invention to the base paper, various papers and paperboards can be mentioned. For example, PPC
Paper, inkjet recording paper, laser printer paper, foam paper, thermal transfer paper, recording paper such as thermal recording paper, coated paper such as art paper, quest coated paper, high quality coated paper, wrapping paper such as kraft paper, pure white roll paper, etc. Examples include Western paper such as notebook paper, book paper, printing paper, and newsprint, paperboard for paper containers such as manila balls, white balls, and chip balls, and paperboard such as liners.

The concentration of the coating liquid when applying the particle type surface sizing agent of the present invention is usually 0.1 to 5% by weight, preferably 0.2 to 1% by weight. If the amount is less than 0.1% by weight, the sizing effect may be insufficient, and if the amount exceeds 5% by weight, the sizing effect is hardly improved, which is not preferable because 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.

[0049]

The present invention will be described in more detail with reference to Synthesis Examples, Examples and Comparative Examples below, but the present invention is not limited to these Examples.

(Synthesis Example 1) Method for producing acrylamide copolymer [A] 1 equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet pipe
116 parts of water, 208 parts of ethanol, 306 parts of 50% acrylamide (99 mol%), 3 parts of isobutyl methacrylate (1 mol%), and 3.4 parts of sodium methallylsulfonate were added to a liter four-necked flask. The temperature was raised to 60 ° C. while mixing and stirring under an air flow. 10 at 60 ° C
A 2.5% aqueous solution of ammonium persulfate was added, the temperature was raised to 78 ° C. by the heat of polymerization, and the mixture was kept for 1.5 hours. 10%
An aqueous solution of ammonium persulfate (0.7 part) was added, and the mixture was kept for 1 hour to complete the polymerization reaction. Then water 320
Add ethanol, distill off ethanol and dilute with water to make a concentration of 20%
An aqueous solution of an acrylamide copolymer was obtained. Table 1 shows the composition and properties of the obtained acrylamide copolymer (A-1).

(Synthesis Examples 2 to 11) Production of Acrylamide Copolymers (A-2 to A-11) In Synthesis Example 1, acrylamide (a1), anionic monomer (a2), and other copolymerizable vinyl Acrylamide-based copolymers (A-2 to A-11) were obtained in the same manner as in Synthesis Example 1, except that the mixing ratio of the monomer (a3) and the alkyl mercaptan was changed as shown in Table 1.

Table 1 shows the properties of the obtained acrylamide copolymer.

(Synthesis Example 12) An ammonium aqueous solution of a styrene-acrylic acid copolymer (S-1) for a comparative example was synthesized according to Reference Example 2 of JP-A-8-246391.

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 added dropwise over 3 hours, and the mixture was aged for 2 hours and reacted. Completed. Thereafter, isopropyl alcohol was distilled off, and after cooling, a 28% aqueous ammonia solution was added.
4 parts (100 mol% based on acrylic acid) were added and diluted with water to prepare a copolymer having a concentration of 20%.
Thus, an aqueous solution of the water-soluble copolymer was obtained.

[0055]

[Table 1]

Example 1 In the same reactor as in Synthesis Example 1,
275 parts of water, 100 parts of an aqueous solution of the acrylamide copolymer of A-1 of Synthesis Example 1 (20 parts as a solid content), 20 parts of styrene, 80 parts of normal butyl acrylate, and 1 part
5 parts by weight of a 0% ammonium persulfate aqueous solution was 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 particle type surface sizing agent having a solid content of 25%.

(Examples 2 to 17, Comparative Examples 1 and 2) Table 2 shows the type and amount of the acrylamide-based copolymer, the type of the hydrophobic monomer (b1), and the type and the composition ratio of the anionic monomer (b2). A particle-type surface sizing agent was obtained in the same manner as in Example 1 except for changing as shown.

(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) In a reactor similar to that of Synthesis Example 1, 299 parts of water, a commercially available low-molecular-weight activator Newcol 271A (manufactured by Nippon Emulsifier Co., Ltd., alkyldiphenyldisulfonate, 5
0% product) 4 parts (2 parts as solid content), styrene 35 parts,
55 parts of normal butyl acrylate, 10 methacrylic acid
, 10% ammonium persulfate aqueous solution 5 parts by weight,
The temperature was raised 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 5 295 parts of water, 16 parts of acrylamide, 1 part of isobutyl methacrylate, 17 parts of styrene, 66 parts of normal butyl acrylate and 5 parts by weight of a 10% aqueous ammonium persulfate solution were added to the same reactor as in Synthesis Example 1. The temperature was raised to 80 ° C. while mixing and stirring under a nitrogen stream.

After about 10 minutes at 80 ° C., gelling occurred, and no comparative surface sizing agent was obtained.

(Comparative Example 6) As Comparative Example 6, a commercially available styrene-acrylic surface sizing agent SS315 (manufactured by PMC Japan) was used.

[0066]

[Table 2]

(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) (PM
C; AL120), 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 (manufactured by Hymo; NR12MLS) of 0.01% with respect to pulp was added, and paper was made with a Noble and Wood paper machine so as to have a basis weight of 65 g / m2. 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) 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. The pH of the coating solution was adjusted to 8 or 6 with caustic soda or sulfuric acid.

Solid content of coating liquid: oxidized starch 6%
Surface sizing agent 0.3% (3) Production and evaluation of acidic woodfree paper The coating liquid blended in the above (2) is applied to the base paper made in the above (1) using a size press, and the acidic woodfree paper is coated. Obtained.
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 3 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.

[0071]

[Table 3]

Test Example 2 Evaluation on 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 Japan 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. The pH of the coating solution was adjusted to 8 or 6 with caustic soda or sulfuric acid.

Solid content concentration of coating liquid: oxidized starch 6%
Surface sizing agent 0.3% (3) Production and evaluation of neutral high-quality paper The coating liquid blended in (2) above is applied to the base paper made in (1) using a size press, I got the paper.
The obtained test paper is kept at a constant temperature and humidity (20 ° C., 65% relative humidity).
The humidity was controlled in an environment for 24 hours, and the measurement of the degree of Stekigto sizing and the degree of pen writing sizing was performed in the same manner as in Test Example 1.
Table 4 shows the results.

[0075]

[Table 4]

Test Example 3 Evaluation on Inkjet Recording Paper (1) Preparation 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, calcium carbonate (TP121S, manufactured by Okutama Kogyo Co., Ltd.) and 5% talc (manufactured by Fuji Talc: ND talc) based on 1% (based on absolute dry weight) of pulp. ) Was added. In addition, 1.0% (based on absolute dry weight) of a sulfuric acid band based on pulp, amphoteric starch (manufactured by National Starch Co., Ltd .; Cato3210) based on 0.5% (based on absolute dry weight) based on pulp and 0.3 based on pulp were used.
% (Absolute dry weight basis) rosin sizing agent for neutral paper (Japan P
MC; CC167) was added successively, and the pH was 7.5.
This pulp slurry was diluted to a concentration of 0.25% with dilution water. Then, the diluted pulp slurry is added to pulp 4
% (Based on absolute dry weight) of calcium carbonate (manufactured by Okutama Kogyo KK; TP121S) and a retention improver (manufactured by Hymo NR12MLS) of 0.01% based on pulp, and the basis weight is 65 g with a Noble & Wood paper machine. / 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.) 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.

Solid content concentration of coating liquid: oxidized starch 5%
Surface sizing agent 0.25% Salt 0.25%

(3) Production of Recording Paper The coating liquid mixed in the above (2) was applied to the recording base paper made in the above (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 sizing test and inkjet suitability test were performed.

(I) Evaluation of sizing degree In the same manner as in the measurement of the sizing degree in Test Example 1, the Stekigt sizing degree and the pen writing sizing degree were measured. Table 5 shows the results.

(Ii) Ink Jet Suitability Test Method The ink jet suitability was evaluated by calendering the test paper obtained in the size effect test and then subjecting it to a constant temperature and humidity (20
(C, 65% relative humidity) in an environment for 24 hours or more, and then using a bubble jet printer BJ-220JC manufactured by Canon Inc. according to the following method. Table 5 shows the results.

(A) Print density test A solid print was printed on a 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 printed 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.

[0086]

[Table 5]

(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.

Solid concentration of coating liquid: oxidized starch 5%
Surface sizing agent 0.25% Salt 0.25%

(2) Evaluation of foaming property of coating liquid 600 g of the coating liquid mixed in the above (1) was put into a foam cell having an inner diameter of 7 cm and a length of 50 cm, and circulated under the following conditions.
The height (mm) of the foam was measured. Table 6 shows the results.

The coating liquid temperature was 60 ° C., the circulation pump flow rate was 9 liter / min, and the circulation time was 3 minutes.

In Table 6, the lower the foam height, the better the foamability (the smaller the foaming amount).

(Test Example 5) Mechanical Stability Test 50 g of the coating solution prepared in the above (1) was put into 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 6 shows the results.

(Test Example 6) Stability test for metal ions A 5% aqueous solution of a sulfuric acid band was dropped into 50 ml of a 0.3% dispersion of a surface sizing agent in solid content.

One drop (about 0.3 ml) to three drops (about 0.9 m)
x), 4 drops (about 1.2 ml) ~
Agglomeration occurs in the range of seven drops (about 2.1 ml).
A sample that did not cause aggregation even when seven or more drops (2.1 ml) were dropped was evaluated as ○.

[0095]

[Table 6]

From the results of evaluation on acidic high-quality paper in Table 3 and the results of evaluation on neutral high-quality paper in Table 4, the surface sizing agents of Examples
It was found that the influence on the change in the pH of the coating solution was small, and that the degree of Stekigt sizing and the degree of pen writing sizing were better than the surface sizing agent of the comparative example.

From the evaluation results of the ink jet recording papers shown in Table 5, the surface sizing agents of the examples were superior to the surface sizing agents of the comparative example in print density, feathering, strike-through evaluation, Stecht sizing degree, and pen writing sizing degree. It turned out to be good.

From the evaluation results shown in Table 6, the foaming property of the surface sizing agent of the example was lower than that of the comparative example, and the mechanical stability was better than that of the comparative example. It was found that the amount of residue was small and the stability to metal ions was better for the surface sizing agent of the example than for the surface sizing agent of the comparative example.

[0099]

Industrial Applicability The present invention is excellent in mechanical stability, low foaming property and storage stability of the sizing agent itself, and when used as a surface sizing agent, can improve sizing performance from acidic paper to neutral paper. It has excellent inkjet suitability for information paper, especially inkjet paper, and has low foaming property in coating liquid, compatibility with other concomitant chemicals, and stable surface for dissolved metal ions. A sizing agent can be provided.

Continuation of the front page (72) Inventor Mako Takahashi 17-2 Yawata Kaigandori, Ichihara-shi, Chiba Pref.

Claims (9)

[Claims] 1. A particle type obtained by emulsion-polymerizing a hydrophobic monomer (b1) in the presence of a (meth) acrylamide-based copolymer [A] comprising at least 68 mol% of (meth) acrylamide (a1). Surface sizing agent. 2. In the presence of a (meth) acrylamide-based copolymer [A] comprising at least 68 mol% of (meth) acrylamide (a1), 70 to 99.9% by weight of a hydrophobic monomer (b1) and 30 A particle-type surface sizing agent obtained by emulsion-polymerizing the component [B], which contains 0.1 to 0.1% by weight of an anionic monomer (b2). 3. The component (A) is obtained by copolymerizing 99.9 to 70 mol% of (meth) acrylamide (a1) and 0.1 to 30 mol% of an anionic monomer (a2). The particle type surface sizing agent according to claim 1 or 2, which is a (meth) acrylamide copolymer. 4. The composition according to claim 1, wherein the component (A) comprises 69.9 to 99.8 mol% of (meth) acrylamide (a1) and 0.1 to 30%.
Mole% of anionic monomer (a2), 0.1 to 20
Mol% of other copolymerizable vinyl monomers (a3)
The particle type surface sizing agent according to claim 1 or 2, which is a (meth) acrylamide copolymer obtained by copolymerizing 5. The component (A) is a (meth) acrylamide copolymer obtained by copolymerizing (meth) acrylamide (a1) in the presence of an alkyl mercaptan [C] having 6 to 22 carbon atoms. The particle type surface sizing agent according to claim 1 or 2, wherein 6. The component (A) comprises 70 to 99.9 mol% of (meth) acrylamide (a1) and 0.1 to 30 mol% of an anionic monomer (a2), and has 6 to 22 carbon atoms.
The particle type surface sizing agent according to any one of claims 1 to 3, which is a (meth) acrylamide-based copolymer obtained by copolymerization in the presence of an alkyl mercaptan [C]. 7. The composition according to claim 1, wherein the component (A) is 69.9 to 99.8 mol% of (meth) acrylamide (a1) and 0.1 to 30%.
Mole% of anionic monomer (a2), 0.1 to 20
Mol% of other copolymerizable vinyl monomers (a3)
Is a (meth) acrylamide-based copolymer obtained by copolymerizing a C 6 to C 22 alkyl mercaptan [C], and the particle type surface according to claim 1 or 2. Sizing agent. 8. The weight ratio of the (meth) acrylamide copolymer [A] to the total amount [B] of the hydrophobic monomer (b1) and the anionic monomer (b2) is 10 to 50: 1.
The particle type surface sizing agent according to any one of claims 1 to 7, wherein the particle size sizing agent is 00. 9. The method according to claim 5, wherein the alkyl mercaptan [C] is used in an amount of 0.01 to 2 mol per 100 mol of the monomer component of the (meth) acrylamide copolymer [A]. The particle type surface sizing agent according to any one of the above.