JPH11241295A - Surface-coating composition and production of coated paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a surface-coating composition that can impart excellent physical properties such as internal strength, air permeation, blister resistance on printing to the paper by mixing a specific water-soluble resin with aluminum sulfate at a specific ratio. SOLUTION: At least one of water-soluble resin selected from the group consisting of starches, polyvinyl alcohols and anionic polyacrylamides and ammonium sulfate are mixed at a weight ratio of 100/ (1-25) on the solid basis to prepare the objective surface-coating composition. This composition is diluted in the range of 1-15 wt.% on the solid basis and wood free paper is coated with the resultant diluted coating liquid by using a double roll sizing press or the like in an amount of 0.02-5 g/m<2> and is dried with a drum drier to produce the objective coated paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface coating composition for use in surface coating of paper and the like, and a coating composition in which a coating liquid containing the surface coating composition is applied to paper. The present invention relates to a paper manufacturing method. More specifically, the present invention relates to a surface coating composition having excellent internal strength and air permeability, and a method for producing a coated paper obtained by applying a coating liquid containing the surface coating composition to paper.

[0002]

2. Description of the Related Art Conventionally, surface coating agents for improving the internal strength and surface strength of paper include starch derivatives such as starch, oxidized starch, cationized starch and enzyme-modified starch, and carboxymethyl cellulose. Cellulose derivatives, or polyvinyl alcohols, synthetic water-soluble polymers such as polyacrylamide resins are used,
Above all, polyacrylamide-based resins have an excellent paper-strength enhancing effect, and the amount of use thereof has tended to increase in recent years.

[0003] As a coating agent for paper containing the above-mentioned polyacrylamide resin as a main component, JP-A-5-302298 discloses acrylamides and α, β-unsaturated monocarboxylic acids, α, β-unsaturated monocarboxylic acids in the presence of ureas. An acrylamide-based resin composition obtained by polymerizing a saturated dicarboxylic acid or unsaturated sulfonic acid or a salt thereof as an essential component is disclosed,
It is said that the surface strength and internal strength of the paper are thereby improved. However, when such a conventional water-soluble resin is applied, the internal strength of the paper is improved, but there is a problem that the air permeability of the paper is reduced. In particular, when the amount of coating is large, the air permeability is extremely reduced, so that there have been cases where problems such as poor drying properties with an after-dryer and deterioration of the drying properties of ink at the time of printing are caused.

On the other hand, with regard to pigment-coated paper requiring high-level printing, demand for improvement in paper quality is increasing with the spread of multicolor printing and high-speed printing. Above all, countermeasures against "blister" that occurs in the drying process after printing is the most important paper quality. As a countermeasure against the blister, there is a case where a method of improving the air permeability of the coat layer by making the coat layer porous is used. However, since blisters are generated from inside the paper, improvement from the coated base paper itself is desirable. For that purpose, it is necessary to further increase the internal strength of the paper and improve the air permeability, and it is excellent in the internal strength improvement effect,
The appearance of a surface coating agent capable of obtaining good air permeability has been awaited.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a surface coating composition having excellent internal strength of paper, good air permeability, and little blistering when printing pigment-coated paper. It is an object of the present invention to provide a method for producing a coated paper in which a coating liquid containing the surface coating composition is applied to paper.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that starches (a), polyvinyl alcohols (b), and anionic polyacrylamides (c) can be used. By mixing ammonium sulfate with at least one selected water-soluble resin [A],
It was found that excellent internal strength and air permeability were obtained, and that blister generation after pigment coating was small, and the present invention was completed.

That is, the present invention comprises at least one water-soluble resin [A] selected from starches (a), polyvinyl alcohols (b) and anionic polyacrylamides (c), and ammonium sulfate, And the weight ratio of solid content of [A] and ammonium sulfate is 100: 1 to 25.
A surface coating composition, and a method for producing a coated paper, in which a coating liquid containing the surface coating composition is coated on paper, and further a coated paper. Is a method for producing the above-mentioned coated paper, which is a coated base paper.

The starches (a), polyvinyl alcohols (b) and anionic polyacrylamides (c) used as the water-soluble resin [A] used in the present invention are described below. (1) As starches (a), processed starches based on corn, potato, tapioca, potato, rice, wheat flour and the like can be used. As the processing method, those manufactured by various methods can be used. Usually, oxidized starch modified with an oxidizing agent such as sodium hypochlorite, enzyme-modified starch treated with an enzyme, 3-chloro-2 Cationized starch modified with a tertiary agent such as -hydroxypropyldimethylamine or a quaternizing agent such as 3-chloro-2-hydroxypropyltrimethylammonium chloride;
Etherified starch and esterified starch such as carboxymethyl starch and hydroxymethyl starch can be used. The above-mentioned starches (a) are not particularly limited in their aqueous solution viscosities, but usually have a viscosity of 1 to 100 in a Brookfield viscometer (60 rpm) of 25 ° C., 10% solids aqueous solution.
0 cps, preferably 5 to 500 cps, more preferably 10 to 100 cps.

(2) As the polyvinyl alcohols (b), those produced by various methods can be used, but usually those produced by hydrolysis or alcoholysis (alcoholization) of polyvinyl esters are used. it can. The polyvinyl ester includes a homopolymer of vinyl ester, a copolymer of two or more vinyl esters, and a copolymer of vinyl ester with another ethylenically unsaturated monomer. Here, as the vinyl ester, vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, vinyl pivalate and the like can be used, and among them, industrially produced and inexpensive vinyl acetate can be suitably used. There are various other ethylenically unsaturated monomers copolymerizable with a vinyl ester, and there is no particular limitation.For example, α-olefins, halogen-containing monomers, carboxylic acid-containing monomers, (Meth) acrylic acid ester, vinyl ether, sulfonic acid-containing monomer, amide group-containing monomer, amino group-containing monomer, fourth
Examples thereof include a quaternary ammonium salt-containing monomer, a silyl group-containing monomer, a hydroxyl group-containing monomer, and an acetyl group-containing monomer. The degree of polymerization of the polyvinyl alcohols (b) is not particularly limited, but is usually from 500 to 2
0000, and preferably 1,000 to 4,000. The degree of saponification of polyvinyl alcohols is not particularly limited, but is usually 60 to 100 mol%, preferably 80 to 100 mol%, more preferably 95 to 100 mol%.

(3) The anionic polyacrylamide (c) can be obtained by copolymerizing an acrylamide monomer (m) and an anionic vinyl monomer (n). As the acrylamide monomers (m),
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 (n) include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, unsaturated tricarboxylic acids, unsaturated tetracarboxylic acids, unsaturated sulfonic acids, unsaturated phosphonic acids, and salts thereof. And at least one selected from the group consisting of:

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 and ammonium salts such as sodium and potassium salts thereof, and dicarboxylic anhydrides such as maleic anhydride. Is mentioned.

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, 2-acrylamido-2-methylpropane sulfonic acid and alkali metal salts such as sodium salt and potassium salt thereof, and ammonium salts. No. 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 (n), unsaturated monocarboxylic acids, unsaturated dicarboxylic acids and salts thereof, specifically acrylic acid, itaconic acid and salts thereof are preferable in view of the effect of improving the internal strength, Particularly preferred are unsaturated dicarboxylic acids and salts thereof, specifically, itaconic acid and salts thereof.

The copolymer is made anionic by the copolymerization of the acrylamide monomer (m) and the anionic vinyl monomer (n). The copolymer is hydrolyzed with an acid or alkali compound to hydrolyze the carbamoyl moiety. And an anionic group can also be introduced. In addition to the acrylamide monomers (m) and the anionic vinyl monomers (n) used for the anionic polyacrylamides (c), nonionic vinyl monomers copolymerizable with the above (m) and (n) and A cross-linking agent can be used as long as the performance is not hindered.

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 0 to 20% by weight based on the total amount of the acrylamide monomer (m) and the anionic vinyl monomer (n).

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, tetramethylol methanetetraacrylate, tetraallyl pyromellylate, tetraallylamine salt, tetraalylamine Tetrafunctional vinyl monomers such as Ruokishietan,

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 to 5% by weight based on the total amount of the acrylamide monomer (m) and the anionic vinyl monomer (n).

The anionic polyacrylamides (c) used in the present invention can also be obtained by polymerizing in the presence of ureas according to the method described in JP-A-5-302298. It is preferable to use the anionic polyacrylamides (c) obtained in the presence of urea from the viewpoint of improving the internal strength.

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% with respect to the total amount of the acrylamide monomer (m) and the anionic vinyl monomer (n).
30% by weight is preferred.

The weight ratio of the component (m) to the component (n) used in the anionic polyacrylamides (c) (m) /
(N) is 99.5 to 50% / 0.5 to 50%, preferably 98 to 80% / 2 to 20%. When the amount of the anionic vinyl monomer (n) is less than 0.5% by weight, the effect of improving the internal strength may be insufficient, and when the amount exceeds 50% by weight, a further effect on the internal strength is expected. Can not.

In the reaction of the anionic polyacrylamides (c), the total concentration of the monomers constituting the component (c) is 5 to 50% by weight, preferably 10 to 10% in a predetermined reaction vessel.
The reaction is carried out at a reaction temperature of 40 to 100 ° C. for 1 to 10 hours using a known and commonly used polymerization initiator. 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 for the reaction of the anionic polyacrylamides (c) is not particularly limited, and any known and commonly used one can be used. Examples of the radical polymerization initiator include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; benzoyl peroxide; tert-butyl hydroperoxide;
peroxides such as tert-butyl peroxide; bromates such as sodium bromate and potassium bromate; Examples thereof include percarbonates such as potassium carbonate and ammonium percarbonate, and perphosphates such as sodium perphosphate, 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 usually 0.01 to 5% by weight based on the total amount of the monomers used for the anionic polyacrylamides (c).

Further, in order to adjust the molecular weight of the anionic polyacrylamides (c), known and commonly used chain transfer agents may be used, if necessary. For example, allyl compounds such as allyl alcohol, allylamine, (meth) allylsulfonic acid or an alkali metal salt thereof, mercaptoethanol, thioglycolic acid or an alkali metal salt or ammonium salt thereof, isopropyl alcohol, and sodium hypophosphite are included. . These chain transfer agents are 2
More than one species may be used in combination. The amount of the chain transfer agent to be used is usually 0.1 to 10% by weight based on the total amount of the monomers used for the anionic polyacrylamides (c).

Anionic polyacrylamides (c)
Has a solid content of 5 to 50% by weight, preferably 10 to 4% by weight.
0% by weight aqueous solution having a viscosity at 25 ° C. (Brookfield rotational viscometer) of 500 to 15,000 cp.
s, preferably 1,000 to 10,000 cps, more preferably 2,000 to 5,000 cps. 1
If it exceeds 5,000 cps, the coating workability may deteriorate, and if it is less than 500 cps, the effect of improving the internal strength may be inferior.

Further, the pH of the anionic polyacrylamides (c) can be appropriately adjusted using an acid or an alkali after the completion of the reaction. As the acid and alkali,
Inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid; organic acids such as formic acid, 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. , Ammonia, methylamine, dimethylamine, and other amine bases can be used.

Among the starches (a), polyvinyl alcohols (b), and anionic polyacrylamides (c) used as the water-soluble resin [A], (c) has the effect of improving the internal strength, and Pigment coated paper is excellent in the effect of suppressing blistering during printing, and is particularly preferable.

The amount of ammonium sulfate used in the present invention is based on 100 parts by weight of the solid content of the water-soluble resin [A].
1 to 25 parts by weight. The amount of ammonium sulfate used is 1
If the amount is less than 25 parts by weight, the effect on air permeability is insufficient. If the amount is more than 25 parts by weight, the effect of improving the internal strength becomes insufficient, and both are inferior in the effect of suppressing the generation of blisters. Further, when a large amount of ammonium sulfate is used, the above-mentioned [A] completely dissolved in water is insolubilized, which is not preferable in terms of coating suitability and is inferior in the effect of improving internal strength. Within the above range, considering the balance between internal strength and air permeability, the solid content of the above [A] is 10%.
The amount is preferably 5 to 20 parts by weight with respect to 0 parts by weight.

The surface coating composition of the present invention comprises at least one water-soluble resin [A] selected from starches (a), polyvinyl alcohols (b) and anionic polyacrylamides (c). It can be obtained by mixing ammonium sulfate by a conventional method. However, when producing the water-soluble resin [A], ammonium sulfate may be previously mixed in the system.

Next, a method for producing paper in which a coating solution containing the surface coating composition of the present invention is applied to paper will be described below. The surface coating composition of the present invention can be used in combination with celluloses such as carboxymethyl cellulose. Further, the coating liquid containing the surface coating composition may contain additives such as a surface sizing agent, an antislip agent, a preservative, an antifoaming agent, a viscosity modifier, and a dye. When the starch (a) is used for the water-soluble resin [A], the concentration at the time of applying the surface coating composition of the present invention is 0.1 to 20% by weight as solid content, preferably. When the polyvinyl alcohol (b) and the anionic polyacrylamide (c) are used, the solid content is 0.1 to 15% by weight, preferably 1 to 5% by weight. Done. In addition, when the starch (a), polyvinyl alcohols (b), and anionic polyacrylamides (c) are used for the water-soluble resin [A], the coating temperature is preferably 20 to 80 ° C. preferable. The coating amount of the surface coating composition can be appropriately set in consideration of the sizing degree of the base paper and other factors, but when the starch (a) is used as the water-soluble resin [A]. , Usually 0.05 to 10 g / m ² , preferably 0.5 to 5 in solid content.
g / m ² , and when polyvinyl alcohols (b) and anionic polyacrylamides (c) are used, the solid content is usually 0.05 to 5 g / m ² , preferably 0.1 to 5 g / m ² . 2 g / m ² .

The coating solution containing the surface coating composition of the present invention can be applied to paper by a known method. Examples thereof include a size press, a film press, a gate roll coater, and a blade. Coating can be performed using a coater, calender, bar coater, knife coater, or air knife coater. Also, spray coating can be performed.

The coating liquid containing the surface coating composition of the present invention includes newsprint paper, coated base paper, liner, coated ball, white plate, wamp, flame-retardant base paper, postcard base paper, printing writing paper, It can be used for various base papers made from acidic or neutral paper such as foam paper, PPC paper, inkjet paper, heat-sensitive paper, and pressure-sensitive paper. Among these, it is particularly effective when used for coated base paper, for which blister control is a serious problem. Also, the size of the base paper is arbitrary, but when applying 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 effect of ammonium sulfate used in the present invention has not yet been confirmed, but when the surface coating composition of the present invention is applied to paper, the water-soluble resin [A] and ammonium sulfate are used in the drying step. It is presumed that some kind of interaction occurs, and therefore, the air permeability becomes better than when the above [A] is used alone. Inorganic salts other than ammonium sulfate, for example, sodium chloride, potassium chloride, sodium sulfate, calcium sulfate, magnesium sulfate, sodium nitrate, potassium nitrate, etc., have no effect described in the present invention. It is considered that they are working during.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described with specific examples. In the synthesis of the anionic polyacrylamide (c) used in the present invention, when the component (m) and the component (n) are reacted, 80 to 98 parts by weight of (m) acrylamide in the reaction vessel, Acrylic acid 2 to 20 parts by weight, and water with 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 wt%, viscosity 2,000 to 10,000 cps (25
C)) of the anionic polyacrylamide (c).

When ureas are used in addition to the above components (m) and (n), 85 to 98 parts by weight of (m) acrylamide and 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 20.
~ 50 wt%, viscosity 2,000 ~ 10,000 cps
(25 ° C.) to obtain anionic polyacrylamides (c).

Next, the surface coating composition of the present invention will be described. When the starch (a) is used as the water-soluble resin [A], ammonium sulfate is used in an amount of 1 to 30 parts by weight based on 100 parts by weight of the aqueous solution of starch having a solid concentration of 1 to 30% by weight.
By mixing 25 parts by weight, a surface coating composition having a solid content of 1 to 30% by weight and a viscosity of 5 to 10,000 cps (25 ° C.) is obtained.

When polyvinyl alcohols (b) are used as the water-soluble resin [A], ammonium sulfate is used in an amount of 1 to 25 parts by weight based on 100 parts by weight of the solid content of an aqueous polyvinyl alcohol solution having a solid content of 1 to 20% by weight. Parts, a solid content concentration of 1 to 20% by weight, and a viscosity of 5 to 10,000 c.
A ps (25 ° C.) surface coating composition is obtained.

When the anionic polyacrylamide (c) is used as the water-soluble resin [A], the solid content of the anionic polyacrylamide (c) obtained above is 100%.
1 to 25 parts by weight of ammonium sulfate are mixed with the parts by weight, and the solid content concentration is 10 to 50% by weight, and the viscosity is 500 to 10%.
A surface coating composition of 000 cps (25 ° C.) is obtained.

Next, the coated paper of the present invention will be described.
The solid content concentration of the surface coating composition obtained above is 1 to 1
A coating solution was prepared by diluting to 5% by weight. this
The coating liquid is solidified on high quality paper using a 2-roll size press.
0.02 to 5 g / m in minutes ^TwoAnd then dora
Coated paper is obtained by drying
You.

[0041]

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.

Synthesis Example 1 (Synthesis of anionic polyacrylamides (c)) In a 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube, 287.7 parts of water, 50%
169.6 parts of an aqueous acrylamide solution, 19.0 parts of 80% acrylic acid, and 1.0 part of sodium methallylsulfonate were charged, and the temperature was raised to 50 ° C. Next, after sufficient removal of oxygen in the reaction system with nitrogen gas, 4.6 parts of a 5% aqueous ammonium persulfate solution and 1.0 part of a 5% aqueous sodium metabisulfite solution were added. After 40 minutes, the temperature in the reaction system is 85 ° C.
And further reacted at a temperature of 80 ° C. for 2 hours. Then, 24.8 parts of water and 20% sodium hydroxide
Add 4 parts, solid concentration 20.6%, pH 7, viscosity 4,
000 cps (25 ° C.) of anionic polyacrylamide c-1 was obtained.

Synthesis Example 2 286.4 parts of water, 50% in a 1-liter four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen inlet tube
10. acrylamide aqueous solution 273.0 parts, itaconic acid
4 parts, 1.6 parts of sodium methallylsulfonate, urea 3
7.3 parts were charged, and the temperature was raised to 50 ° C. Next, after sufficient removal of oxygen in the reaction system with nitrogen gas, 4.6 parts of a 5% aqueous ammonium persulfate solution and 1.0 part of a 5% aqueous sodium metabisulfite solution were added. After 25 minutes, the temperature in the reaction system rose to 90 ° C, and the reaction was further performed at a temperature of 80 ° C for 2 hours. Thereafter, 3.8 parts of water and 12.3 parts of a 30% aqueous sodium hydroxide solution were added, and the solid content was 30.3%.
An anionic polyacrylamide c-2 having H7 and a viscosity of 5,100 cps (25 ° C.) was obtained.

Synthesis Example 3 In a 1-liter four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen inlet tube, 243.9 parts of water, 50%
Acrylamide aqueous solution (200 parts) and isopropyl alcohol (26.7 parts) were charged and heated to 50 ° C. Next, after sufficiently removing oxygen in the reaction system with nitrogen gas, 5%
4.6 parts of an aqueous potassium persulfate solution and 1.0 part of a 5% aqueous sodium metabisulfite solution were added. After 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. Thereafter, 19.2 parts of water was added, and the solid content
0.2%, pH 8.6, viscosity 3,800 cps (25
C)) to obtain nonionic polyacrylamide c-3.

Example 1 In an aqueous solution a-1 of oxidized starch (MS-3800: manufactured by Nippon Shokuhin Kako Co., Ltd.) having a solid content of 15%, ammonium sulfate was 5 parts per 100 parts of the solid content of a-1. Were mixed to obtain a surface coating composition B.

Examples 2 to 7, Comparative Examples 1 to 3 Except that the amount of ammonium sulfate in Example 1 was changed to the amount shown in Table 1, oxidized starch was converted to polyvinyl alcohol (PVA-117: Kuraray Co., Ltd.) having a solid concentration of 7%. )) Aqueous solution b-
1, anionic polyacrylamide c- of Synthesis Examples 1 and 2
1, c-2, and nonionic polyacrylamide c-
Except having changed to 3, it mixed by the same method as Example 1, and obtained surface coating composition C-H (Examples 2-7) and mixed aqueous solution i-k (Comparative Examples 1-3). .

Comparative Example 4 15 parts of the ammonium sulfate of Example 6 was replaced with sodium chloride 1
Mixing was carried out in the same manner as in Example 1 except that the amount was changed to 5 parts, to obtain a mixed aqueous solution 1.

Example 8 The surface coating composition B obtained in Example 1 was diluted with water,
The coating liquid was adjusted so that the solid content concentration was 12%. This coating solution is applied to both sides of uncoated neutral high-quality paper (basis weight 80 g / m ² , ash content 6%, AKD sizing agent internal paper) using a two-roll size press (solid content coating). 1.5g /
m ² ) and dried with a drum dryer (80 ° C., 50 seconds) to obtain coated paper T-1. After drying, 20 ° C,
The humidity was controlled for 24 hours in a constant temperature and humidity room of 65 RH% (relative humidity). Thereafter, the coated paper T-1 was subjected to various evaluation tests (the blister resistance was evaluated after pigment coating the coated paper). The results are shown in Table 2.

Example 9, Comparative Example 5 Coating was carried out in the same manner as in Example 8, except that the surface coating composition B was changed to the surface coating composition C and the water-soluble resin a-1. And coated paper T-2 (Example 9) and t-1 (Comparative Example 5). Thereafter, the coated paper was subjected to various evaluation tests. The results are shown in Table 2. Comparative Example 5 is an example in which ammonium sulfate was not used, and was inferior in air permeability and poor in blister resistance.

Example 10 The surface coating composition D obtained in Example 3 was diluted with water,
The coating liquid was adjusted so that the solid content concentration was 5%. this
Uncoated neutral high-quality paper (basis weight 80 g / m2) ^Two,ash
6%, AKD sizing paper)
Using a surface coating (solid coating amount 0.6 g /
m^Two), Dry with a drum dryer (80 ° C, 50 seconds)
By drying, a coated paper T-3 was obtained. After drying, coated paper T
-3 was subjected to various evaluation tests. The results are shown in Table 3.

Example 11, Comparative Example 6 Coating was carried out in the same manner as in Example 10, except that the surface coating composition D was changed to the surface coating composition E and the water-soluble resin b-1. , Coated paper T-4 (Example 11), t-2
(Comparative Example 6) was obtained. The results are shown in Table 3. Comparative Example 6
Is an example in which ammonium sulfate is not used, and has poor air permeability and poor blister resistance.

Example 12 The surface coating composition F obtained in Example 5 was diluted with water,
The coating liquid was adjusted so that the solid content concentration was 4%. this
Uncoated neutral high-quality paper (basis weight 80 g / m2) ^Two),Ash
6%, paper with no internal sizing agent added)
Using a double-sided coating (solid coating amount 0.8g /
m^Two), Dry with a drum dryer (80 ° C, 50 seconds)
By drying, a coated paper T-5 was obtained. After drying, 20 ° C,
The humidity was controlled in a constant temperature and humidity chamber of 65 RH% for 24 hours. That
Thereafter, the coated paper T-5 was subjected to various evaluation tests. Table 4 shows the results
It was shown to.

Examples 13 and 14, Comparative Examples 7 to 10 The same procedures as in Example 12 were carried out except that the surface coating composition F was changed to the surface coating compositions G and H, and the mixed aqueous solutions i to 1. Coated paper T-6 (Example 13), T-coated
7 (Example 14), t-3 to t-6 (Comparative Examples 7 to 10)
I got The results are shown in Table 4. Comparative Examples 7 and 8 are examples in which the amount of ammonium sulfate used is out of the range of the present invention,
It is inferior in the effect of internal strength or air permeability and inferior in blister resistance. Comparative Example 9 is an example using nonionic polyacrylamide containing no anionic vinyl monomer (m), and was inferior in the effect of internal strength. Comparative Example 10 used sodium chloride instead of ammonium sulfate. It is an example and is inferior in the effect of air permeability, and both comparative examples are inferior in blister resistance.

Comparative Example 11 Coating was carried out in the same manner as in Example 12 except that the surface coating composition F was changed to the water-soluble resin c-1.
7 was obtained. The results are shown in Table 4. Comparative Example 11 is an example in which ammonium sulfate was not used, and was inferior in air permeability and poor in blister resistance.

Comparative Example 12 Example 1 except that the surface coating composition F was changed to water only.
Coating was performed in the same manner as in Example 2 to obtain coated paper t-8. Table 4 shows the evaluation results.

Example 15 The surface coating composition B obtained in Example 1 was diluted with water,
The coating liquid was adjusted so that the solid content concentration was 9%. this
Uncoated neutral high-quality paper (basis weight 80 g / m2) ^Two,ash
6%, paper with no added internal sizing agent) and 2 roll size press
Coating on both sides (solid coating amount 2.2 g / m^Two),
Dry with a drum dryer (80 ° C, 50 seconds)
Thus, coated paper T-8 was obtained. After drying, 20 ℃, 65RH
% In a constant temperature / humidity room for 24 hours. Then coated paper
T-8 was subjected to various evaluation tests. Table 5 shows the results.

Example 16 The surface coating composition D obtained in Example 3 was diluted with water,
The coating liquid was adjusted so that the solid content concentration was 3%. this
Uncoated neutral high-quality paper (basis weight 80 g / m2) ^Two,ash
6%, paper with no added internal sizing agent) and 2 roll size press
Coating on both sides (solid coating amount 0.7g / m^Two),
Dry with a drum dryer (80 ° C, 50 seconds)
Thus, coated paper T-9 was obtained. After drying, 20 ℃, 65RH
% In a constant temperature / humidity room for 24 hours. Then coated paper
T-9 was subjected to various evaluation tests. Table 5 shows the results.

Example 17 The surface coating composition F obtained in Example 5 was diluted with water,
The coating liquid was adjusted so that the solid content concentration was 3%. this
Uncoated neutral high-quality paper (basis weight 80 g / m2) ^Two,ash
6%, paper with no added internal sizing agent) and 2 roll size press
Coating on both sides (solid coating amount 0.7g / m^Two),
Dry with a drum dryer (80 ° C, 50 seconds)
Thus, coated paper T-10 was obtained. After drying, 20 ℃, 65R
The humidity was controlled for 24 hours in a constant temperature and humidity chamber of H%. Then coating
Paper T-10 was subjected to various evaluation tests. The results are shown in Table 5.
Was.

The evaluation test of the coated paper was carried out according to the following measuring method. Internal bond; Scott bond (kg · cm): Measured using an internal bond tester (manufactured by Kumagaya Riki Kogyo Co., Ltd.) under conditions of an adhesive pressure of 1 kg / cm ² and 30 seconds. The higher the value of the Scott bond, the better the internal strength.

Air permeability: Air permeability (second: 100 ml): JIS P8117 (using Gurley air permeability meter) The smaller the value of the air permeability, the better the air permeability.

Blister resistance Blister: Each of the coated papers obtained in Examples 8 to 17 and Comparative Examples 5 to 12 was coated with the following pigment color composition I or II (Examples 8 to 11 and Comparative Examples 5 and 12). For Example 6, the pigment color composition I was used, and Examples 12 to 17 were used.
Pigment Color II was used for Comparative Examples 7 to 12) using a bar coater so that the solid coating amount on both sides was 30 g / m ^2, and then immediately
Hot air drying was performed at 10 ° C. for 10 seconds. Further, the roll temperature 6
Under the condition of 0 ° C. and a linear pressure of 50 kg / cm, calender treatment was performed twice on each side (total four times on both sides) to obtain a coated paper. The obtained coated paper was conditioned for 24 hours under the conditions of 20 ° C. and 65% RH (relative humidity). After that, it is 10cm long and 3cm wide
cm of the sample paper was placed in a thermostat bath filled with silicone oil (150 ° C. to 175 ° C .: Examples 8 and 9 in Table 2).
And Comparative Example 5, 160 ° C. to 180 ° C .: Examples 10 and 11 in Table 3 and Comparative Example 6, 180 ° C. to 220 ° C .: Table 4
Examples 12 to 14 and Comparative Examples 7 to 12 at 170 ° C
１９０190 ° C .: Dipped in Examples 15 to 17) in Table 5 for 3 seconds to evaluate blister resistance. At this time, the state of blister generation was visually observed, and grades ranging from excellent to poor 1 (5: no blister was generated) were determined stepwise.

Pigment Color Composition I (solid content 63%, pH 9) “Ultra White 90” (clay manufactured by Engelhard Minerals, USA) 50 parts “FMT90” (calcium carbonate manufactured by Fimatec) 50 parts "T2076M" (latex manufactured by JSR) 11 parts "MS-4600" (starch manufactured by Nippon Shokuhin Kako Co., Ltd.) 3 parts "Aron T-4" (dispersing agent manufactured by Toa Gosei Chemical Co., Ltd.) 0.03 parts Pigment Color composition II (solid content 62%, pH 9) "Ultra White 90" 60 parts "FMT90" 40 parts "T2076M" 11 parts "MS-4600" 4 parts "Alon T-4" 0.03 part

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

[Table 4]

[0067]

[Table 5]

[0068]

As is clear from Tables 2 to 5, the surface coating composition of the present invention is superior in the internal strength and air permeability of the paper as compared with the conventional one, and can be used for printing pigment-coated paper. It turns out that it is excellent in blister resistance. By applying the surface coating composition of the present invention to paper, it becomes possible to obtain a coated paper having excellent internal strength and good air permeability. It is particularly effective when used for coated base paper.

Claims (3)

[Claims] 1. A composition comprising at least one water-soluble resin [A] selected from starches (a), polyvinyl alcohols (b), and anionic polyacrylamides (c), and ammonium sulfate. ] And a solid content weight ratio of ammonium sulfate to 100: 1 to 25. 2. A method for producing coated paper, comprising applying a coating liquid containing the surface coating composition according to claim 1 to paper. 3. The method for producing coated paper according to claim 2, wherein the coated paper is coated base paper.