JPH111889A - Improving agent composition for quality of paper surface and production of coated paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an improving agent composition for quality of paper surface, excellent in improving effect for mechanical strength of paper surface and capable of reducing a sticking power of a paper sheet which has repeatedly adsorbed moisture and of preventing paper powder from being caused by printing operation, and to provide a method for producing a coated paper sheet to which the paper surface quality-improving agent composition is applied. SOLUTION: This composition comprises; an anionic acrylamide-based resin composition [A] obtained by reacting an acrylamide monomer (a) with an anionic vinyl monomer (b), and a hydroxy carboxylic acid [B], wherein a solid weight ratio of [A] and [B] is (100:0.2) to (100:10). The other objective method for producing a coated paper sheet is conducted by applying a coating liquid containing the composition to a paper sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface paper quality improving composition used for surface coating of paper and the like, and a method for producing a coated paper obtained by applying the surface paper quality improving composition to paper. More specifically, a surface paper quality improver composition which is excellent in paper surface strength, has low tackiness when re-wet, and is excellent in preventing paper dust generated during printing, and the surface paper quality improvement The present invention relates to a method for producing a coated paper obtained by applying an agent composition to paper.

[0002]

2. Description of the Related Art Hitherto, surface paper quality improvers for improving the surface strength and printability of paper include starch derivatives such as starch, oxidized starch, cationized starch and enzyme-modified starch, and carboxymethyl cellulose. Cellulose derivative, polyvinyl alcohol (hereinafter abbreviated as PVA)
And natural and synthetic water-soluble polymers such as polyacrylamide resins, among which cheap starch derivatives are most frequently used.

[0003] However, starch derivatives and PVA require a step of cooking and dissolving them when used, so that workability is poor, and starches have problems such as spoilage and aging. And boiling (phenomenon in which a coating liquid jumps on a coating machine roll) in terms of coating suitability. Therefore, recently, starches,
In many cases, a polyacrylamide-based resin is applied to paper instead of PVA.

[0004] Coating agents for paper containing the above-mentioned polyacrylamide resin as a main component are disclosed in JP-A-5-302298, JP-A-8-260384, and the like, mainly for the purpose of improving the surface strength. Has been proposed. However, when these water-soluble resins are applied, the surface strength of the paper is improved, but the paper becomes tacky when the paper is re-wetted. Therefore, when placed in high humidity conditions,
In some cases, the paper is re-moistened by blocking due to adhesion of papers or dampening water at the time of printing, resulting in problems such as blanket stains in which fine fibers (paper powder) on the paper surface adhere to the blanket.

Further, recently, higher surface paper quality has been required, and the conventional surface paper quality improver has not been able to provide a sufficient result, resulting in insufficient printing strength due to insufficient paper surface strength and paper surface tackiness. Trouble is increasing. In particular, in recent news paper and the like, color printing, high-speed mass printing, and high blending of deinked pulp (DIP) have been progressing, and stricter paper quality is required than before. Countermeasures have become a serious problem.

[0006] Therefore, in order to prevent the generation of paper dust in the printing process, there is a need for a surface paper quality improver that minimizes the stickiness of the paper surface when re-wet, in addition to the excellent surface strength improving effect. ing. Under such circumstances, Japanese Patent Application Laid-Open No. Hei 6-192959 discloses that paper succinic acid and / or substituted succinic acid are used in paper surface finishing agents such as starch and anionic polyacrylamide.
Or by applying a combination of substituted succinic acid derivatives,
A method for preventing the tackiness of paper upon rewetting is disclosed in Japanese Patent Application No. Hei.
No. 46892 discloses an anionic acrylamide-based resin composition containing (poly) alkylene glycol, (poly)
Methods have been proposed to prevent the stickiness of the paper upon rewetting by mixing at least one compound selected from the group consisting of glycerin, but none of these methods has been effective yet.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to a surface paper quality improving agent which is excellent in improving the surface strength of paper, has low tackiness when paper is re-wetted, and prevents the generation of paper dust during printing. An object of the present invention is to provide a composition and a method for producing a coated paper obtained by applying the surface paper quality improving composition to paper.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, mixed hydroxycarboxylic acids [B] with anionic polyacrylamide resin composition [A]. As a result, it was found that the paper surface had low tackiness in the case of re-wetting together with an excellent surface strength improving effect, and the present invention was completed.

That is, the present invention provides (1): an anionic acrylamide resin composition [A] and a hydroxycarboxylic acid [B] obtained by reacting an acrylamide monomer (a) with an anionic vinyl monomer (b).
And the weight ratio of solids between [A] and [B] is 10
0: 0.2 to 10; and (2) a hydroxycarboxylic acid [B],
The surface paper quality improver composition according to the above (1), which is at least one selected from the group consisting of salicylic acid, malic acid, tartaric acid, and alkali metal salts or ammonium salts thereof,
(3): The composition for surface paper quality according to the above (1), wherein the hydroxycarboxylic acid [B] is salicylic acid and its alkali metal salt or ammonium salt, (4): the above (1)
A method for producing a coated paper, wherein a coating liquid containing the surface paper quality improver composition according to any one of (1) to (3) is applied to paper;
(5): To provide a method for producing a coated paper according to the above (4), wherein the paper is newsprint.

Next, the present invention will be described in detail. The acrylamide monomers as the component (a) used in the anionic acrylamide resin composition [A] of the present invention include:
Acrylamide and methacrylamide are preferred.
-Methyl (meth) acrylamide, N-ethyl (meth)
Acrylamide, N, N-dimethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-
Any one or more of N-substituted (meth) acrylamides such as t-octyl (meth) acrylamide can be used in combination with acrylamide and methacrylamide.

The anionic vinyl monomers of the component (b) used in the present invention include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, unsaturated tricarboxylic acids, unsaturated tetracarboxylic acids, unsaturated sulfonic acids, and unsaturated sulfonic acids. Phosphonic acid,
And at least one member selected from the group consisting of salts thereof, and examples thereof are given below.

Examples of unsaturated monocarboxylic acids and salts thereof include acrylic acid, methacrylic acid, crotonic acid and salts thereof such as alkali metal salts such as sodium salt and potassium salt and ammonium salts. Examples of unsaturated dicarboxylic acids and salts thereof include maleic acid, fumaric acid, itaconic acid, citraconic acid, and alkali metal salts such as sodium salt and potassium salt thereof, and ammonium salts.

The unsaturated tricarboxylic acids and their salts include aconitic acid, 3-butene-1,2,3-tricarboxylic acid, 4-pentene-1,2,4-tricarboxylic acid and their sodium and potassium salts And the like, alkali metal salts and ammonium salts. Examples of unsaturated tetracarboxylic acids and salts thereof include 1-pentene-1,1,4,4-tetracarboxylic acid, 4-pentene-1,2,3,4-tetracarboxylic acid, 3-hexene-1, Examples thereof include 1,6,6-tetracarboxylic acid and alkali metal salts such as sodium salt and potassium salt thereof, and ammonium salts.

The unsaturated sulfonic acids and salts thereof include vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and alkali metal salts thereof such as sodium salt and potassium salt. Ammonium salts and the like. Examples of the unsaturated phosphonic acid and salts thereof include vinylphosphonic acid, α-phenylvinylphosphonic acid, and alkali metal salts such as sodium salt and potassium salt thereof, and ammonium salts. Among such anionic vinyl monomers (b), itaconic acid, acrylic acid and salts thereof are preferred in view of the effect of improving the surface strength, and itaconic acid and salts thereof are particularly preferred.

An anionic group is introduced into the polymer by copolymerization of the acrylamide monomer (a) and the anionic vinyl monomer (b), and the amide moiety is added to the polymer by using an acid or an alkali compound. By hydrolysis, an anionic group can be further introduced. In addition to the acrylamide monomers (a) and the anionic vinyl monomers (b) used in the anionic acrylamide resin composition [A], nonionic vinyl copolymerizable with the above (a) and (b) Monomers and cross-linking agents can be used within a range that does not hinder performance.

Examples of the nonionic vinyl monomer include esters of alcohol and (meth) acrylic acid, styrene, styrene derivatives, (meth) acrylonitrile,
Examples thereof include vinyl acetate, vinyl propionate, and methyl vinyl ether, and one or more of these can be used. The amount of the nonionic vinyl monomer used is usually 0.1 to 0.1 based on the total amount of the acrylamide monomer (a) and the anionic vinyl monomer (b).
20% by weight.

Examples of the crosslinking agent include di (meth) acrylates such as ethylene glycol di (meth) acrylate and diethylene glycol di (meth) acrylate, and bis (meth) bis (meth) acrylamide and N, N-bisacrylamide acetic acid. (Meth) acrylamides, divinyl adipate, diallyl maleate, N-methylol acrylamide, diallyldimethylammonium, bifunctional vinyl monomers such as glycidyl (meth) acrylate, 1,3,5-triacryloylhexahydro-S- Trifunctional vinyl monomers such as triazine, triallylamine, triallyl isocyanurate, triallyl trimellitate, tetramethylolmethmethanetetraacrylate, tetraallylpyromellilate, tetraallylamine salt, tetra Tetrafunctional vinyl monomers such as allyloxy ethane,

Water-soluble aziridinyl compounds such as tetramethylolmethane-tri-β-aziridinylpropionate and trimethylolpropane-tri-β-aziridinylpropionate; (poly) ethylene glycol diglycidyl ether; ) Water-soluble polyfunctional epoxy compounds such as glycerin diglycidyl ether; 3- (meth)
Acryloxymethyltrimethoxysilane, 2- (meth)
Silicon-based compounds such as acrylamido-2-methylpropyltrimethoxysilane, vinyldimethylmethoxysilane, vinyltrichlorosilane, vinyltriphenoxysilane, 2- (meth) acrylamido-2-methylpropyltriacetoxysilane can be exemplified. One or two or more can be used. The amount of the crosslinking agent used is 0.005 to 5% by weight based on the total amount of the acrylamide monomers (a) and the anionic vinyl monomers (b).

The anionic acrylamide resin composition [A] used in the present invention is disclosed in JP-A-5-30229.
In accordance with the method described in JP-A No. 8 (1996), polymerization can be performed in the presence of ureas. It is preferable to use the anionic acrylamide-based resin composition [A] obtained in the presence of urea from the viewpoint of the paper strength improving effect.

Examples of the ureas include urea, thiourea, ethylene urea, and ethylene thiourea, and one or more of these can be used. Among these,
It is particularly economically preferred to use urea alone. The amount of urea used is 5 to 5% based on the total amount of the acrylamide monomers (a) and the anionic vinyl monomers (b).
30% by weight is preferred.

The weight ratio of the component (a) to the component (b) used in the anionic acrylamide resin composition [A] is as follows:
99.5-50% / 0.5-50%, preferably 98-
80% / 2 to 20%. If the amount of the anionic vinyl monomer (b) is less than 0.5% by weight, the effect of improving the surface strength may be insufficient. Even if the amount exceeds 50% by weight, a further effect on the surface strength is expected. No, not preferred.

In the reaction of the anionic acrylamide resin composition [A], the total concentration of the monomers constituting the component [A] is 5 to 50% by weight, preferably 10 to 40% by weight in a predetermined reaction vessel. And a known and commonly used polymerization initiator at a reaction temperature of 40 to 100 ° C and 1 to 10
Perform under the condition of time. Needless to say, the reaction can also be carried out by continuously dropping the monomer or dividingly adding the monomer in accordance with the characteristics of the monomer component used.

The polymerization initiator used in the reaction of the anionic acrylamide-based resin composition [A] is not particularly limited, and a known and commonly used one can be used. Examples of the radical polymerization initiator include sodium persulfate, potassium persulfate, ammonium persulfate, benzoyl peroxide, t
tert-butyl hydroperoxide, di-tert
-Peroxides such as butyl peroxide, bromates such as sodium bromate and potassium bromate, perborates such as sodium perborate, potassium perborate and ammonium perborate, sodium percarbonate and percarbonate Potassium, percarbonate such as ammonium percarbonate, sodium perphosphate,
Examples thereof include perphosphates such as potassium perphosphate and ammonium perphosphate.

These polymerization initiators can be used alone, but can also be used as a redox polymerization initiator in combination with a reducing agent. Examples of the reducing agent include sulfites, bisulfites, organic amines such as N, N, N ', N'-tetramethylethylenediamine, and 2,2'-azobis-2-.
Azo compounds such as amidinopropane hydrochloride, azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 4,4'-azobis-4-cyanovaleric acid, and reducing sugars such as aldose. Can be illustrated. Two or more of these initiators may be used in combination. The amount of the polymerization initiator used is based on the total amount of the monomers used in the present invention.
Usually, it is 0.01 to 5% by weight.

If necessary, a known and commonly used chain transfer agent may be used. For example, allyl alcohol, allylamine, allyl compounds such as methallyl sulfonic acid or an alkali metal salt thereof, mercaptoethanol, thioglycolic acid or an alkali metal salt or ammonium salt thereof,
Isopropyl alcohol, sodium hypophosphite and the like. These chain transfer agents may be used in combination of two or more. The amount of the chain transfer agent to be used is generally 0.1 to 10% by weight based on the total amount of the monomers used in the present invention.

The anionic acrylamide resin composition [A] used in the present invention has a solid content of 10 to 50% by weight, preferably 20 to 40% by weight, and a viscosity at 25 ° C. (Brookfield rotational viscometer). 500-15,0
00 cps, preferably 1,000 to 10,000 cp
s, more preferably 2,000 to 5,000 cps. If it exceeds 15,000 cps, the coating workability may be deteriorated, and if it is less than 500 cps, the effect of improving the surface strength is inferior.

Further, the pH of the anionic acrylamide resin composition [A] can be appropriately adjusted using an acid or an alkali after the completion of the reaction. Examples of the acid and alkali include sulfuric acid, hydrochloric acid, nitric acid, inorganic acids such as phosphoric acid, formic acid,
Organic acids such as acetic acid and propionic acid, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal carbonates such as sodium carbonate and potassium carbonate, and amine bases such as ammonia, methylamine and dimethylamine can be used. It is.

The hydroxycarboxylic acids [B] used in the present invention are compounds having a hydroxyl group and a carboxyl group in the molecule, for example, salicylic acid, malic acid,
Examples thereof include alkali metal salts such as tartaric acid, oxalic acid, lactic acid and their sodium salts and potassium salts, and ammonium salts. Of the above hydroxycarboxylic acids [B], salicylic acid, malic acid, tartaric acid and salts thereof are preferable,
Particularly, salicylic acid and salts thereof are preferred.

The amount of the hydroxycarboxylic acid [B] used is 0.2 to 10 parts by weight, preferably 0.5 to 7 parts by weight, per 100 parts by weight of the solid content of the anionic acrylamide resin composition [A]. Parts by weight. The amount of [B] used is 0.
If the amount is less than 2 parts by weight, the effect of reducing the tackiness in the case of re-wetting is insufficient, and even if the amount exceeds 10 parts by weight,
No further effect of reducing the tackiness can be expected, and the surface strength may be reduced, which is not preferable.

The surface paper quality improving composition of the present invention can be obtained by mixing the above-mentioned anionic acrylamide resin composition [A] and hydroxycarboxylic acids [B] by a conventional method. The surface paper quality improver composition of the present invention can be used in combination with starches such as starch and oxidized starch, celluloses such as carboxymethyl cellulose, and natural or synthetic water-soluble polymers such as polyvinyl alcohol. Also, surface sizing agent, anti-slip agent, preservative, defoamer,
Additives such as viscosity modifiers and dyes may be used in combination.

The surface paper quality improving composition of the present invention is applied at a coating solution concentration of 0.1 to 15% by weight, preferably 1 to 5% by weight. The coating temperature is 20 to
Preferably, it is performed at 80 ° C. The coating amount of the surface paper quality improver composition can be appropriately set in consideration of the sizing degree of the base paper and other factors, but is usually 0.01 to 5 g / m ² in solid content, preferably 0.05-2g / m
²

Further, the surface paper quality improving composition of the present invention comprises:
It can be applied to paper by a known method, for example, size press, film press, gate roll coater,
The coating can be performed using a blade coater, a calender, a bar coater, a knife coater, or an air knife coater. Also, spray coating can be performed.

Further, the surface paper quality improving composition of the present invention comprises:
Newsprint paper, coated base paper, liner, coated ball, white board, wamp, flame-retardant base paper, postcard base paper, printing and writing paper, foam paper, PPC paper, inkjet paper, thermal paper,
It can be used for various base papers made from acidic or neutral paper such as pressure-sensitive paper. Among these, it is particularly effective when used for newsprint, in which the generation of paper dust during printing is a serious problem. Further, the sizing degree of the base paper is arbitrary, but when coating is performed using a size press or the like, it is preferable to use an internal sizing agent for the purpose of adjusting the liquid absorption of the base paper.

[0034]

The hydroxycarboxylic acids [B] used in the present invention have an effect of reducing the tackiness when re-wet. Although no confirmation has been obtained for the effect of suppressing the adhesiveness of the hydroxycarboxylic acid, when the surface paper quality improver composition of the present invention is applied to paper, the hydroxycarboxylic acid [B] is converted to a paper such as a sulfuric acid band. It is speculated that this is due to strong coordination to the cationic substance in the inside. When the anionic acrylamide-based resin composition [A] is used alone, the anionic acrylamide-based resin composition [A] is re-wetted by interacting with a cationic substance in paper such as a sulfate band. Becomes more sticky. The hydroxycarboxylic acids [B] used in the present invention have an effect of blocking the interaction between the anionic acrylamide-based resin composition [A] and the cationic substance in the paper, and as a result, when re-wetting. It is considered that the effect of reducing the tackiness is exhibited.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described. In the synthesis of the anionic acrylamide-based resin composition [A] used in the present invention, when the component (a) and the component (b) are reacted, 80 to 98 parts by weight of (a) acrylamide is added to the reaction vessel. (B) 2 to 20 parts by weight of acrylic acid and water having a monomer concentration of 10 to 10
The reaction system was charged so as to be 40% by weight, and oxygen in the reaction system was sufficiently removed with nitrogen gas.
After adding 1 to 1 part by weight, the reaction is carried out at a reaction temperature of 40 to 100 ° C. for 1 to 10 hours. Thereafter, the pH was adjusted to 5 to 8 using sodium hydroxide, and the solid content
0% by weight, viscosity 2,000 to 5,000 cps (25
C)), thereby obtaining an anionic acrylamide-based resin composition [A].

When ureas are used in addition to the components (a) and (b), 85 to 98 parts by weight of (a) acrylamide and (b) 2 to 15 parts of itaconic acid are added to the reaction vessel.
Parts by weight, 5 to 30 parts by weight of urea and water were charged so that the monomer concentration was 10 to 40% by weight, and oxygen in the reaction system was sufficiently removed with nitrogen gas. At a reaction temperature of 40-100.
The reaction is carried out at a temperature of 1 to 10 hours. Thereafter, the pH was adjusted to 5 to 8 using sodium hydroxide, and the solid concentration was adjusted to 10 to 10.
~ 50 wt%, viscosity 2,000 ~ 5,000 cps (2
5 ° C.) anionic acrylamide resin composition [A]
Is obtained.

When a crosslinking agent is used in addition to the components (a) and (b), 85 to 98 parts by weight of (a) acrylamide, (b) 3-butene-1,
2 to 15 parts by weight of 2,3-tricarboxylic acid, 0.01 to 2 parts by weight of methylenebisacrylamide and water are charged so that the monomer concentration becomes 10 to 40% by weight, and oxygen in the reaction system is sufficiently supplied with nitrogen gas. , Potassium persulfate was added in an amount of 0.01 to 1 part by weight, and the reaction temperature was reduced to 40 to 1.
The reaction is performed at 00 ° C. for 1 to 10 hours. Thereafter, the pH was adjusted to 5 to 8 using an aqueous ammonia solution, the solid content concentration was 10 to 40% by weight, and the viscosity was 2,000 to 5,000 cps.
(25 ° C.) to obtain an anionic acrylamide resin composition [A].

Next, the surface paper quality improving composition of the present invention will be described. With respect to 100 parts by weight of the solid content of the anionic acrylamide resin composition [A] obtained above,
0.2 to 10 parts by weight of sodium salicylate are mixed, and p
H5-9, solids concentration 10-50% by weight, viscosity 2,000
A surface paper quality improver composition of 0 to 5,000 csp (25 ° C.) is obtained.

Further, 0.2 to 10 parts by weight of malic acid is mixed with 100 parts by weight of the solid content of the above-mentioned anionic acrylamide resin composition [A], and the pH is 2 to 8 and the solid concentration is 10 to 50 weight parts. %, Viscosity 2,000-5,000cs
A p (25 ° C.) surface paper quality improver composition is obtained.

Further, 0.2 to 10 parts by weight of ammonium tartrate are mixed with 100 parts by weight of the solid content of the above-mentioned anionic acrylamide resin composition [A],
9. Solid content concentration 10-50% by weight, viscosity 2,000-
A surface paper quality improver composition of 5,000 csp (25 ° C.) is obtained.

Next, the coated paper of the present invention will be described.
The surface paper quality improver composition obtained above has a solid content concentration of 1
A coating solution was prepared by diluting the solution to 〜5% by weight. This coating solution is applied to newsprint paper at 0.05 to 1 g / m ² as a solid using a bar coater at a temperature of 20 to 60 ° C., and then dried by a drum dryer. Paper is obtained.

[0042]

The present invention will be described below in more detail with reference to examples and comparative examples. Parts and% are based on weight. Further, the present invention is not limited to the following embodiments. The evaluation test of the coated paper was performed according to the following measuring method. Surface strength: dry pick: RI printing tester, nip width 10 mm Ink: FINE INK. (Manufactured by Dainippon Ink and Chemicals, Inc.) V. = 24 In all cases, the peeled state after printing was visually observed, and 10 levels were evaluated as 10 being excellent and 1 being poor. The larger the value of the dry pick, the better the surface strength.

Adhesion at the time of rewetting: Adhesive strength: The coated papers obtained in Examples 6 to 10 and Comparative Examples 6 to 14 were cut into a width of 3 cm and a width of 10 cm to prepare two test pieces. did. The two test pieces were immersed in water for 3 seconds, the coated surfaces were overlapped with each other, sandwiched between filter papers to remove excess water, and then subjected to a surface pressure of 100 kg / cm ² using a hot press adjusted to a temperature of 60 ° C. For 2 minutes to obtain a measurement sample paper. Then, an extension type tensile tester (tensile speed 30 m
m / min) to perform a T-peel test on the sample paper,
The adhesive strength between the test pieces was measured. The smaller the value of the adhesive strength, the lower the tackiness of the paper surface when rewet. The higher the value of the surface strength and the smaller the value of the adhesive strength, the more excellent the effect of preventing the generation of paper dust during printing. In order to solve the problem of the present invention, the value of dry pick is 9 or more, and the value of adhesive strength is 20 (g).
f) The following effects are considered necessary.

Synthesis Example 1 (Synthesis of anionic acrylamide resin composition [A]) 287.7 parts of water was placed in a 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube. %
169.6 parts of acrylamide aqueous solution (solid content: 84.8)
Parts), 19.0 parts of an aqueous 80% acrylic acid solution (solid content 1)
5.2 parts) and 0.9 part of sodium methallylsulfonate were charged and heated to 60 ° C. Next, after sufficient removal of oxygen in the reaction system with nitrogen gas, 3.2 parts of a 5% ammonium persulfate aqueous solution was added. After about 30 minutes, the temperature in the reaction system rose to 80 ° C, and the reaction was further performed at a temperature of 80 ° C for 2 hours. Thereafter, 24.8 parts of water was added, the pH was adjusted to 7 with a 20% aqueous sodium hydroxide solution, and the solid concentration was adjusted to 2%.
An anionic acrylamide-based resin composition A-1 having a viscosity of 4,000 cps and 0.2% was obtained.

Synthesis Example 2 In a 1-liter four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen inlet tube, 377.3 parts of water, 50%
185.8 parts of acrylamide aqueous solution (solids 92.9
Parts), 7.1 parts of itaconic acid, 0.5 part of sodium methallylsulfonate and 25 parts of urea, and the temperature was raised to 60 ° C. Next, after sufficiently removing oxygen in the reaction system with nitrogen gas, 3.1 parts of a 5% ammonium persulfate aqueous solution was added. After about 40 minutes, the temperature in the reaction system rises to 80 ° C,
The reaction was further performed at a temperature of 80 ° C. for 2 hours. Then water 3
0.0 part was added, the pH was adjusted to 7 with a 20% aqueous sodium hydroxide solution, the solid content concentration was 20.3%, and the viscosity was 3.1.
00 cps anionic acrylamide resin composition A
-2 was obtained.

Synthesis Example 3 In a 1-liter four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen inlet tube, 257.7 parts of water, 50%
185.8 parts of acrylamide aqueous solution (solids 92.9
Parts), 7.1 parts of itaconic acid, 1.0 part of sodium methallylsulfonate and 31.5 parts of a 1% aqueous solution of methylenebisacrylamide, and the temperature was raised to 60 ° C. Next, after sufficiently removing oxygen in the reaction system with nitrogen gas, 3.1 parts of a 5% aqueous potassium persulfate solution was added. After about 40 minutes, the temperature in the reaction system rose to 80 ° C, and the reaction was further performed at a temperature of 80 ° C for 2 hours. Then, 10.0 parts of water was added, and 20
The pH was adjusted to 7 with a 5% aqueous ammonia solution to obtain an anionic acrylamide resin composition A-3 having a solid content of 20.1% and a viscosity of 4,700 cps.

Synthesis Example 4 In a 1-liter four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen inlet tube, 277.5 parts of water, 50%
200.0 parts of acrylamide aqueous solution (solid content 100
Parts) and 1.0 part of sodium methallylsulfonate, and the temperature was raised to 60 ° C. Next, after sufficiently removing oxygen in the reaction system with nitrogen gas, 3.1 parts of a 5% aqueous potassium persulfate solution was added. After about 30 minutes, the temperature in the reaction system becomes 8
The temperature was raised to 5 ° C, and further reacted at a temperature of 80 ° C for 2 hours. Thereafter, 24.1 parts of water was added, and the solid content concentration was 20.8.
%, A viscosity of 3,800 cps and a pH of 8 to obtain an anionic acrylamide resin composition A-4.

Example 1 100 parts (as solid content) of the anionic acrylamide resin composition A-1 obtained in Synthesis Example 1 and 2 parts of sodium salicylate were mixed to obtain a surface paper quality improver composition C. Was.

Examples 2 to 5, Comparative Examples 1 to 3 Anionic acrylamide resin compositions [A] and hydroxycarboxylic acids [B] shown in Table 1 were mixed in the same manner as in Example 1 to obtain a surface paper quality improver composition. Products DG (Examples 2 to 2)
5) Mixed aqueous solutions h to j (Comparative Examples 1 to 3) were obtained.

Comparative Example 4 A mixed aqueous solution k was obtained in the same manner as in Example 1 except that 5 parts of polyethylene glycol having a weight average molecular weight of 300 was used instead of sodium salicylate.

Comparative Example 5 A mixed aqueous solution 1 was obtained in the same manner as in Example 1 except that 5 parts of octenyl succinic anhydride was used instead of sodium salicylate.

Example 6 A surface paper quality improver composition C obtained in Example 1 was diluted with water to prepare a coating solution such that the solid content concentration was 4%.
This coating liquid was applied to uncoated newsprint paper (basis weight 45 g / m ² ). One-side coating was carried out using a three-bar coater and dried with a drum dryer (80 ° C., 50 seconds). After drying, 20
The humidity was controlled for 24 hours in a thermo-hygrostat at 65 ° C. and a relative humidity of 65%. Thereafter, it was subjected to various evaluation tests. Table 2 shows the results.

Examples 7 to 10 and Comparative Examples 6 to 10 Surface paper quality improving composition C was replaced with surface paper quality improving compositions D to G.
(Examples 7 to 10), mixed aqueous solutions h to l (Comparative Examples 6 to 1)
Coating and evaluation were carried out in the same manner as in Example 6, except that the composition was changed to 0). Table 2 shows the results. Comparative Examples 6 and 7
Is an example in which the amount of the hydroxycarboxylic acid [B] used is outside the range of the present invention, and is inferior to either the effect of reducing the adhesiveness or the effect of improving the surface strength. Comparative Example 8
This is an example using an acrylamide-based resin composition containing no anionic vinyl monomer (b), and is inferior in the effect of improving the surface strength. Comparative Examples 9 and 10 are examples in which polyethylene glycol and octenyl succinic anhydride were used instead of the hydroxycarboxylic acids [B], and the effect of reducing the adhesive strength was still insufficient.

Comparative Example 11 Coating and evaluation were carried out in the same manner as in Example 6, except that the surface paper quality improver composition C was changed to the anionic acrylamide resin composition A-1. Table 2 shows the results. Comparative Example 11 was an example in which the hydroxycarboxylic acids [B] were not used, and had a high adhesive strength.

Comparative Example 12 Surface paper quality improver composition C was applied to PVA (P
VA-117: Kuraray Co., Ltd.) Coating and evaluation were carried out in the same manner as in Example 6, except that the aqueous solution was changed.
Table 2 shows the results. This is an example in which PVA was used in place of the surface paper quality improver composition of the present invention, and the effect of improving surface strength was poor and the adhesive strength was remarkably large.

Comparative Example 13 A surface paper quality improver composition C was replaced with an aqueous solution of oxidized starch (MS-3800: manufactured by Nippon Shokuhin Kako Co., Ltd.) having a solid content of 4% in the same manner as in Example 6. Coating and evaluation were performed. Table 2 shows the results. This is an example in which oxidized starch was used in place of the surface paper quality improver composition of the present invention, and the effect of improving the surface strength was poor.

Comparative Example 14 Coating and evaluation were carried out in the same manner as in Example 6, except that the surface paper quality improver composition C was changed to water only. Table 2 shows the results. This is an example in which only water was used instead of the surface paper quality improver composition of the present invention, and the surface strength improving effect was remarkably inferior.

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

As is clear from Table 2, the surface paper quality improver composition of the present invention has a better balance between the effect of improving the paper surface strength and the tackiness when re-wetted as compared with the conventional one. It turns out that it is excellent. By applying the surface paper quality improver composition of the present invention to paper, it becomes possible to obtain a coated paper having excellent surface strength and low adhesiveness.

Claims (5)

[Claims] Claims: 1. An anionic acrylamide resin composition [A] obtained by reacting an acrylamide monomer (a) with an anionic vinyl monomer (b) and a hydroxycarboxylic acid [B], and [A] ] And [B]
Wherein the weight ratio of the solid content to the surface paper is 100: 0.2 to 10. 2. The method according to claim 1, wherein the hydroxycarboxylic acid [B] is at least one selected from the group consisting of salicylic acid, malic acid, tartaric acid, and alkali metal salts or ammonium salts thereof. Surface paper quality improver composition. 3. The surface paper quality improving composition according to claim 1, wherein the hydroxycarboxylic acid [B] is salicylic acid and its alkali metal salt or ammonium salt. 4. A method for producing coated paper, comprising applying a coating liquid containing the surface paper quality improving composition according to claim 1 to paper. 5. The method for producing coated paper according to claim 4, wherein the paper is newsprint.