JPH0913296A - Liquid agent for improving surface quality of paper - Google Patents

Abstract

PURPOSE: To improve the surface strength, internal bond strength and sizing effect of paper in balanced state. CONSTITUTION: The objective liquid agent contains an aqueous solution of an acrylamide resin composition produced by reacting (A) an acrylamide compound with (B) an anionic vinyl monomer in the presence of (C) at least one kind of resin selected from styrene-acrylic acid resin, styrene-acrylic acid-acrylic acid ester resin, styrene-maleic acid resin, styrene-maleic acid-maleic acid half- ester resin, (di)isobutylene-maleic acid resin and (di)isobutylene-maleic acid-maleic acid half-ester resin and (D) a urea compound.

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 liquid agent which improves the surface strength, internal strength and size effect of paper in a well-balanced manner and is excellent in product stability.

[0002]

2. Description of the Related Art In recent years, the development of printing technology has been remarkable, and with the increase in printing speed and quality, it has become more and more demanding for printing paper to improve its printability such as surface strength, internal strength and size. It has come to be demanded. In order to meet these requirements, papermaking chemicals have been added (internally added) to an aqueous pulp slurry or coated (externally added) on the surface of paper. Of these, the internal additive has an insufficient chemical yield, while the external additive has a chemical yield of almost 100.
%, Which is known to be more advantageous because it acts directly on the surface of the paper.

Conventionally, a mixture of alkenyl succinate and a polyacrylamide type substance (Japanese Patent Publication No. 60-1016
No. 0) is known. A polyacrylamide resin obtained by polymerizing acrylamide and an anionic vinyl monomer in the presence of urea as a surface paper quality improver which is excellent in improving the surface strength, internal strength, water resistance and the like of paper (Japanese Patent Laid-Open No. Hei 5) -302298) is known.

[0004]

However, the conventional surface paper quality improvers have not been sufficiently satisfactory in response to the recent demand for a high degree of surface paper quality improvement. However, it was insufficient to improve the size property in a well-balanced manner. For example, when the surface paper quality improver of the above-mentioned conventional technique (Japanese Patent Publication No. 60-10160) is applied to the surface of a non-sized paper by a gate roll coater, a size press or the like, the surface strength and the internal strength are improved, but the size The improvement of sex is not enough. Further, when the same is applied to strong size paper, the size effect is not improved but rather deteriorated, which is regarded as a problem.

Therefore, if the mixing ratio of the hydrophobic component (alkenyl succinate) of the surface paper quality improving agent of the above-mentioned conventional technique (Japanese Patent Publication No. 60-10160) is increased in order to improve the size effect, the size property is improved. Improved, on the other hand,
It is not preferable because the surface strength and the internal strength are significantly reduced. In addition, a method of increasing the hydrophobicity of the hydrophobic component itself (alkenyl succinate) without increasing the mixing ratio to enhance the size effect is not preferable because the compatibility with the polyacrylamide-based substance used in combination decreases.

Further, a polyacrylamide resin obtained by polymerizing acrylamide and an anionic vinyl monomer in the presence of ureas (JP-A-5-302298).
Has a very excellent effect of improving the surface strength and internal strength of paper, but the effect of improving the sizing property is not sufficient. Therefore, it has been strongly desired to develop a surface paper quality improving agent that improves the surface strength and the internal strength as well as the size property in a well-balanced manner.
The present invention provides a surface paper quality improving liquid agent for solving the above problems.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted diligent research to meet the demand, and as a result, styrene-acrylic acid resin, styrene-acrylic acid-acrylic acid ester resin, styrene-maleic acid resin, styrene. -Maleic acid-Maleic acid half ester resin, (di) isobutylene-
In the presence of at least one resin (a) selected from the group consisting of maleic acid resin and (di) isobutylene-maleic acid-maleic acid half ester resin and ureas (b),
By using a surface paper quality improving liquid agent containing an aqueous solution of an acrylamide resin composition obtained by reacting acrylamides (c), an anionic vinyl monomer (d) and optionally a crosslinking agent (e), surface strength is improved. The inventors have found that the size effect is improved in a well-balanced manner together with the internal strength, and the present invention has been completed.

That is, the present invention provides a styrene-acrylic acid resin, a styrene-acrylic acid-acrylic acid ester resin, a styrene-maleic acid resin, a styrene-maleic acid-maleic acid half-ester resin, a (di) isobutylene-maleic acid resin and (Di) isobutylene-maleic acid-
Obtained by reacting an anionic vinyl monomer (d) with acrylamides (c) in the presence of at least one resin (a) selected from the group consisting of maleic acid half-ester resins and ureas (b). A surface paper quality improving liquid agent containing an aqueous solution of an acrylamide resin composition,

Alternatively, styrene-acrylic acid resin, styrene-acrylic acid-acrylic acid ester resin, styrene-maleic acid resin, styrene-maleic acid-maleic acid half ester resin, (di) isobutylene-maleic acid resin and (di) isobutylene -Maleic acid-maleic acid half-ester resin, in the presence of at least one resin (a) selected from the group consisting of urea (b) and acrylamides (c), anionic vinyl monomer (d), It is intended to provide a surface paper quality improving liquid agent containing an aqueous solution of an acrylamide resin composition obtained by reacting a crosslinking agent (e).

The resin (a) is used in an amount of 1 to 50 parts by weight, the urea (b) is used in an amount of 5 to 100 parts by weight, and the anionic vinyl monomer (d) is 0 to 100 parts by weight of the acrylamides (c). 0.5 to 50 parts by weight, or 100 parts by weight of acrylamides (c), the resin (a) is 1 to
50 parts by weight, 5 to 100 parts by weight of urea (b), 0.5 to 50 parts by weight of anionic vinyl monomer (d), and 0.005 to 10 parts by weight of crosslinking agent (e) are preferable. .

Further, the resin (a) is preferably a styrene-acrylic acid resin, and the acrylamides (c) are preferably acrylamide or methacrylamide. Further, the anionic vinyl monomer (d) is an unsaturated monocarboxylic acid, an unsaturated dicarboxylic acid,
It is preferably at least one selected from the group consisting of unsaturated tricarboxylic acid, unsaturated tetracarboxylic acid, unsaturated sulfonic acid, unsaturated phosphonic acid, and salts thereof.

Next, the present invention will be described in detail. Styrene-acrylic acid resin, styrene-acrylic acid-acrylic acid ester resin, which is the resin of component (a) used in the present invention,
Styrene-maleic acid resin, styrene-maleic acid-maleic acid half ester resin, (di) isobutylene-maleic acid resin and (di) isobutylene-maleic acid-maleic acid half ester resin are bulk polymerization, solution polymerization, emulsion polymerization, etc. Polymerized by any of the above methods may be used, but a bulk polymer is particularly preferable. When a powdered resin is used, it needs to be saponified to form an aqueous solution before or during the polymerization.

The alkali used for saponification is one or two selected from sodium hydroxide, potassium hydroxide, ammonia, sodium silicate, sodium aluminate, monoethanolamine, triethanolamine and the like.
More than one organic or inorganic alkali can be used. In addition, styrene and acrylic acid, styrene and acrylic acid and acrylic ester, styrene and maleic acid, styrene and maleic acid and maleic acid half ester, (di) isobutylene and maleic acid, (di) isobutylene and maleic acid and maleic acid half ester. The composition ratio and molecular weight of the ester are not particularly limited as long as they do not impair the stability of the acrylamide resin composition.

As the resin (a), GSA2302 (styrene-acrylic acid resin: manufactured by Gifu Shellac), GSA
2303 (styrene-acrylic acid-acrylic acid ester resin: manufactured by Gifu Shellac), SMA3000 (styrene-maleic acid resin: manufactured by Elf Atchem), SMA2
000 (styrene-maleic acid resin: manufactured by Elf Atchem), isoban 10 (isobutylene-maleic acid resin: manufactured by Kuraray Co., Ltd.) and the like. Particularly, styrene-acrylic acid resin is preferable.

Examples of the urea as the component (b) used in the present invention include urea, thiourea, ethylene urea, ethylene thiourea and the like, and urea is particularly preferable.

As the acrylamides of the component (c) used in the present invention, acrylamide and methacrylamide are preferable, and N-methyl (meth) acrylamide,
Any one or more of N-substituted acrylamides such as N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nt-octyl (meth) acrylamide and the like are acrylamide and methacryl. It can also be used in combination with an amide.

The component (d) anionic vinyl monomer used in the present invention is unsaturated monocarboxylic acid, unsaturated dicarboxylic acid, unsaturated tricarboxylic acid, unsaturated tetracarboxylic acid, unsaturated sulfonic acid, unsaturated phosphonic acid. And the salts thereof are exemplified below.

Examples of the unsaturated monocarboxylic acid and salts thereof include acrylic acid, methacrylic acid and their alkali metal salts such as sodium and potassium salts, ammonium salts and the like.

Examples of unsaturated dicarboxylic acids and salts thereof include maleic acid, fumaric acid, itaconic acid, citraconic acid and their alkali metal salts such as sodium and potassium salts, or ammonium salts.

The unsaturated tricarboxylic acid and salts thereof include aconitic acid, 3-butene-1,2,3-tricarboxylic acid, 4-pentene-1,2,4-tricarboxylic acid and their sodium and potassium salts. Examples thereof include alkali metal salts and ammonium salts.

Unsaturated tetracarboxylic acids and salts thereof include 1-pentene-1,1,4,4-tetracarboxylic acid, 4-pentene-1,2,3,4-tetracarboxylic acid and 3-hexene. Examples thereof include -1,1,6,6-tetracarboxylic acid and their alkali metal salts such as sodium and potassium salts or ammonium salts.

Examples of unsaturated sulfonic acids include vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and their alkali metal salts such as sodium and potassium salts, ammonium salts and the like. To be

Examples of the unsaturated phosphonic acid include vinylphosphonic acid, α-phenylvinylphosphonic acid and their alkali metal salts such as sodium and potassium salts or ammonium salts.

Of the above anionic vinyl monomers, itaconic acid, acrylic acid and salts thereof are preferable, and itaconic acid and salts thereof are particularly preferable. As a method of introducing an anionic group, a method of introducing an anionic group by hydrolyzing an acrylamide resin composition with an acid or an alkali can be used in addition to the method of using an anionic vinyl monomer.

The above (a), (b), (c) and (d)
In addition to the components, a cationic vinyl monomer copolymerizable with dimethylaminopropyl (meth) acrylamide and its quaternary compound, or an amount of nonionic vinyl monomer that does not impair the compatibility and water solubility of the obtained resin composition. Can also be used.

Examples of the cationic vinyl monomer include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide or diethylamino. Vinyl monomers having tertiary amino groups such as propyl (meth) acrylamide, alkyldiallylamine, dialkylallylamine, diallylamine and allylamine, secondary amino groups and primary amino groups, or salts thereof, sulfuric acid, formic acid,
Salts of inorganic or organic acids such as acetic acid,

Alternatively, the vinyl monomer containing a tertiary amino group and an alkyl halide such as methyl chloride or methyl bromide, an arylalkyl halide such as benzyl chloride or benzyl bromide, dimethylsulfate, diethylsulfate, epichlorohydrin or 3-chloro-2. A vinyl monomer containing a quaternary ammonium salt obtained by reaction with a quaternizing agent such as hydroxypropyltrimethylammonium chloride or glycidyltrialkylammonium chloride, eg 2-hydroxy-N, N,
N, N ', N'-pentamethyl-N'-[3-{(1-
Oxo-2-propenyl) amino} propyl] -1,3
-Propanediaminium dichloride and the like are exemplified, and these can be used alone or in combination of two or more.

Examples of the nonionic vinyl monomer include acrylonitrile, methacrylonitrile, styrene, methyl vinyl ether, alkyl ester of (meth) acrylic acid, 2-hydroxy ester, glycidyl ester and the like, and one of these may be used alone or two of them may be used. The above can be used in combination.

The cross-linking agent (e) used in the present invention is
Di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane -Ethylene oxide adduct triacrylate, methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, hexamethylenebis (meth) acrylamide, N, N'-bisacrylamidoacetic acid, N, N'-bisacrylamidoacetate methyl, N, N
-Bis (meth) acrylamides such as benzylidene bisacrylamide,

Divinyl adipates such as divinyl adipate and divinyl sebacate, epoxy acrylates, urethane acrylates, allyl (meth) acrylate,
Bifunctional vinyl monomers such as diallyl phthalate, diallyl malate, diallyl succinate, diallyl acrylamide, divinyl benzene, diisopropyl benzene, N, N-diallyl methacrylamide, diallyl dimethyl ammonium, diallyl chlorendate and glycidyl (meth) acrylate, Trifunctional vinyl monomers such as 1,3,5-triacryloylhexahydro-S-triazine, triallyl isocyanurate, N, N-diallyl acrylamide, triallylamine and triallyl trimellitate,

Tetramethylolmethane tetraacrylate, tetraallyl pyromellitate, N, N, N ', N'
-Tetrafunctional vinyl monomers such as tetraallyl-1,4-diaminobutane, tetraallylamine salt and tetraallyloxyethane, tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-
Tri-β-aziridinyl propionate, 4,4′-
Water-soluble aziridinyl compounds such as bis (ethyleneiminecarbonylamino) diphenylmethane, (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, etc. Water-soluble polyfunctional epoxy compound,

And 3- (meth) acryloxymethyltrimethoxysilane, 3- (meth) acryloxypropyldimethoxymethylsilane, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropylmethyldi Chlorosilane, 3- (meth) acryloxyoctadecyltriacetoxysilane, 3- (meth) acryloxy-2,5-dimethylhexyldiacetoxymethylsilane, 3- (meth) acrylamidopropyltrimethoxysilane, 2- (meth) acrylamidoethyl. Trimethoxysilane, 1- (meth) acrylamidemethyltrimethoxysilane, 2- (meth) acrylamide-2
-Methylpropyltrimethoxysilane, 2- (meth) acrylamido-2-methylethyltrimethoxysilane,

2- (meth) acrylamidoisopropyltrimethoxysilane, 3- (meth) acrylamidopropyltriethoxysilane, N- (2- (meth) acrylamidoethyl) aminopropyltrimethoxysilane,
(3- (meth) acrylamidopropyl) oxypropyltrimethoxysilane, 3- (N-methyl (meth) acrylamide) propyltrimethoxysilane, 3-((meth) acrylamide-methoxy) -3-hydroxypropyltrimethoxysilane, 3-((meth) acrylamide-methoxy) propyltrimethoxysilane, 3- (vinylbenzylaminopropyl) trimethoxysilane,

Dimethyl-3- (meth) acrylamide-
Propyl-3- (trimethoxysilyl) -propylammonium chloride, dimethyl-2- (meth) acrylamido-2-methylpropyl-3- (trimethoxysilyl) -propylammonium chloride, 3- (meth)
Acrylamidopropylmethyldimethoxysilane, 3-
(Meth) acrylamidopropyldimethylmethoxysilane, 3- (meth) acrylamidopropylisobutyldimethoxysilane, 2- (meth) acrylamidopropylisobutyldimethoxysilane, 2- (meth) acrylamido-2-methylpropylmonochlorodimethoxysilane, 2- (meta ) Acrylamido-2-methylpropylhydrogendimethoxysilane,

3- (meth) acrylamidopropylbenzyldiethoxysilane, 3- (meth) acrylamidopropyltriacetoxysilane, 2- (meth) acrylamidoethyltriacetoxysilane, 4- (meth) acrylamidobutyltriacetoxysilane, 2- (Meth) acrylamido-2-methylpropyltriacetoxysilane, N- (2- (meth) acrylamidoethyl) aminopropyltriacetoxysilane, 2- (N-ethyl (meth) acrylamide) ethyltriacetoxysilane, 3
-(Meth) acrylamidopropyloctyldiacetoxysilane, 1- (meth) acrylamidomethylphenyldiacetoxysilane,

3- (meth) acrylamidopropyltripropionyloxysilane, 3- (meth) acrylamidopropyltri (N-methylaminoethoxy) silane, vinyltrichlorosilane, vinylmethyldichlorosilane,
Divinyldichlorosilane, vinylphenyldichlorosilane, vinyldimethylchlorosilane, vinylmethylphenylchlorosilane, vinyldiphenylchlorosilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinylisobutyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, 3-vinyl Benzylaminopropyltriethoxysilane, vinylmethyldiethoxysilane,

Divinyldiethoxysilane, vinyldimethylethoxysilane, vinyldiphenylethoxysilane,
Vinyltriisopropoxysilane, vinyltributoxysilane, vinyldimethylisobutoxysilane, vinyltriphenoxysilane, vinyldimethyl (3-aminophenoxy) silane, vinyldimethyl (4-aminophenoxy) silane, vinyldimethyl (3-methyl-4) -Chlorophenoxy) silane, vinyldimethyl (2-methyl-4)
Examples thereof include silicon compounds such as -chlorophenoxy) silane, vinyltriacetoxysilane, vinylmethyldiacetoxysilane, and vinyldimethylacetoxysilane.

In order to obtain the surface paper quality improving liquid agent of the present invention, a suitable polymerization initiator is used in the reaction, and 40 to 100 is used.
The reaction is carried out at a temperature of ° C for 0.5 to 10 hours. Each component (a), based on 100 parts by weight of acrylamides (c),
The weight ratio of (b), (d) and (e) is as follows. The resin (a) is 1 to 50 parts by weight, preferably 3 to 30 parts.
Parts by weight, and the urea (b) is 5 to 100 parts by weight, preferably 10 to 60 parts by weight, more preferably 10 to 30 parts by weight.
Parts by weight, and the anionic vinyl monomer (d) is 0.
5 to 50 parts by weight, preferably 2 to 20 parts by weight, and the crosslinking agent (e) is 0.005 to 10 parts by weight, preferably 0.
01 to 2 parts by weight.

When the weight ratio of the resin (a), the urea (b), the anionic vinyl monomer (d) and the cross-linking agent (e) is out of this range, the surface strength, internal strength and size effect are well balanced. It is not preferable because it cannot be performed. Also,
When the weight ratio of the cross-linking agent (e) exceeds this range, the product viscosity is high, which is not preferable.

The surface paper quality improving liquid agent obtained by reacting the resin (a) of the present invention with ureas (b) can be synthesized by various conventionally known methods. For example, by charging each component and water in a predetermined reaction vessel so that the monomer concentration is 2 to 40% by weight, preferably 5 to 30% by weight, adding a polymerization initiator, and heating under stirring It is possible to obtain a liquid agent for improving surface paper quality. Of course, the acrylamides (c), the anionic vinyl monomer (d), and the cross-linking agent (e) can be continuously dropped or the like depending on the characteristics to be used.

The polymerization initiator used in the present invention is not particularly limited, and known and commonly used ones can be used. For example, a radical polymerization initiator such as sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, and a ceric salt is added in an amount of 0.01 with respect to the total weight of the acrylamides (c) and the anionic vinyl monomer (d). ~
Use 5% by weight. Further, redox polymerization can be carried out by using a reducing agent such as dimethylamine, sodium hydrogen sulfite and sodium formaldehyde sulfoxylate in combination.

If necessary, known and commonly used chain transfer agents may be used. Examples thereof include allyl compounds such as allyl alcohol and allylamine, mercaptoethanol, thioglycolic acid or its alkali metal salts or ammonium salts, isopropyl alcohol, and sodium hypophosphite.

The surface paper quality improving liquid of the present invention or the coating liquid containing the same is added to an anti-slip agent, a release agent, a rust preventive, a preservative, an antifoaming agent, a viscosity modifier, a dye, a surface sizing agent, a water repellent. You may add additives, such as. Further, the combination with natural or synthetic polymers such as starches, polyvinyl alcohol and carboxymethyl cellulose, and the combination with other surface paper quality improvers are not limited. In addition, the solid content concentration of the coating liquid is usually 0.1 to 15%.

The surface coating solution containing the surface paper quality improving liquid agent of the present invention is applied to paper or paperboard by a method such as size press, film press, gate roll coater, blade coater or calender. It is preferable. Also, bar coater, knife coater,
It can also be coated with an air knife coater or the like.

The coating liquid containing the surface paper quality improving liquid agent of the present invention can be applied to acidic paper or neutral paper. Types of acid paper or neutral paper include coated base paper, newsprint, liner, coated ball, printing writing paper, foam paper, PPC paper, inkjet paper,
Examples include various base papers such as thermal transfer paper and thermal paper. The sizing degree of the base paper is also arbitrary, but when applying using a size press or the like, it is desirable to use an internal sizing agent for the purpose of adjusting the liquid absorption of the base paper.

[0046]

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. Unless otherwise specified, parts and% mean parts by weight and% by weight.

Example 1 A 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube was charged with 342 parts of water and 2 parts of urea.
0 part, 50% acrylamide aqueous solution 200 parts, itaconic acid 2 parts, GSA2302 (styrene-acrylic acid resin)
50 parts of 20% aqueous ammonia solution and 15 parts of isopropyl alcohol were charged and the temperature was raised to 60 ° C. Then, 3.3 parts of a 5% ammonium persulfate aqueous solution was added under the introduction of nitrogen gas, the temperature was raised to 80 ° C., and the reaction was carried out for 2 hours. 28 parts of water was added to the obtained reaction product to obtain a water-soluble resin composition having a solid content of 20.3%, a viscosity of 5500 cps and a pH of 7.4. This is designated as resin A.

Examples 2-8, Comparative Examples 1-6 The types and amounts of the resin (a), ureas (b), acrylamide (c), anionic vinyl monomer (d) and cross-linking agent (e) are shown. Resin B to H and resins i to n (comparative example) were obtained in the same manner as in Example 1 except that the procedure was changed as described in 1. Table 1 shows the results.

Comparative Example 7 105 parts of Resin n, 6.7 parts of 30% aqueous solution of dodecenyl ammonia succinic anhydride and 3.3 parts of water were mixed to obtain a water-soluble resin having a solid content of 20.7%, a viscosity of 3900 cps and a pH of 7.7. Obtained. This is designated as resin o.

Example 9 The above resins A to H and resins i to o (comparative example) were diluted with water,
A coating solution having a solid content concentration of 3% was prepared. This coating solution was applied to uncoated newsprint (grammage 44 [g / m ² ]). One side coating using 3 bar coater, drum dryer (80
It was dried at 50 ° C. for 50 seconds. After drying, the humidity was controlled for 24 hours in a constant temperature and constant humidity chamber at 20 ° C. and a relative humidity of 65%, and then subjected to various evaluation tests. Table 2 shows the results. Table 2 shows an example in which only water was applied.

The evaluation test was conducted by 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. = 18 or 20 The peeled state of the paper after printing was observed with the naked eye, and 5 was evaluated as excellent and 1 was inferior, and a 5-grade evaluation was performed. Internal strength: Scott bond (kgf · cm); Internal bond tester (manufactured by Kumagai Riki Kogyo Co., Ltd.) is used for adhesive strength 5 kg.
/ Cm ² , 30 seconds was measured. Size: Drop test (seconds); TAPPI 33 (water 5μ
It carried out according to l).

Example 10 The coating solution prepared in the same manner as in Example 9 was applied to an uncoated neutral high-quality paper (basis weight: 82 [g / m ² ]) for testing with a size press machine (manufactured by Kumagai Riki Kogyo Co., Ltd.). Coating on both sides (nip pressure 20k
g / cm, coating speed 100 m / min, coating liquid temperature 50 ° C)
And dried with a drum dryer (80 ° C., 50 seconds). After drying, the surface strength, internal strength, and size of each coated paper were measured in the same manner as in Example 9. Table 3 shows the results.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

By using the liquid agent for improving surface paper quality of the present invention, it becomes possible to improve the surface strength, internal strength, and size effect of paper in a well-balanced manner, which could not be achieved by the prior art.

Claims (7)

[Claims] 1. Styrene-acrylic acid resin, styrene-
Group consisting of acrylic acid-acrylic acid ester resin, styrene-maleic acid resin, styrene-maleic acid-maleic acid half ester resin, (di) isobutylene-maleic acid resin and (di) isobutylene-maleic acid-maleic acid half ester resin An aqueous solution of an acrylamide resin composition obtained by reacting an acrylamide (c) with an anionic vinyl monomer (d) in the presence of at least one resin (a) selected from the following and ureas (b): A surface paper quality improving liquid agent characterized by containing. 2. Styrene-acrylic acid resin, styrene-
Group consisting of acrylic acid-acrylic acid ester resin, styrene-maleic acid resin, styrene-maleic acid-maleic acid half ester resin, (di) isobutylene-maleic acid resin and (di) isobutylene-maleic acid-maleic acid half ester resin Acrylamide obtained by reacting an acrylamide (c), an anionic vinyl monomer (d), and a crosslinking agent (e) in the presence of at least one resin (a) selected from the following and ureas (b): A surface paper quality improving liquid agent containing an aqueous solution of a resin composition. 3. Styrene-acrylic acid resin, styrene-
Group consisting of acrylic acid-acrylic acid ester resin, styrene-maleic acid resin, styrene-maleic acid-maleic acid half ester resin, (di) isobutylene-maleic acid resin and (di) isobutylene-maleic acid-maleic acid half ester resin 100 parts by weight of acrylamides (c) in the presence of 1 to 50 parts by weight of at least one resin (a) and 5 to 100 parts by weight of ureas (b) selected from
A surface paper quality improving liquid agent containing an aqueous solution of an acrylamide resin composition obtained by reacting 0.5 to 50 parts by weight of an anionic vinyl monomer (d). 4. Styrene-acrylic acid resin, styrene-
Group consisting of acrylic acid-acrylic acid ester resin, styrene-maleic acid resin, styrene-maleic acid-maleic acid half ester resin, (di) isobutylene-maleic acid resin and (di) isobutylene-maleic acid-maleic acid half ester resin 100 parts by weight of acrylamides (c) in the presence of 1 to 50 parts by weight of at least one resin (a) and 5 to 100 parts by weight of ureas (b) selected from
A surface containing an aqueous solution of an acrylamide resin composition obtained by reacting 0.5 to 50 parts by weight of an anionic vinyl monomer (d) with 0.005 to 10 parts by weight of a crosslinking agent (e). Liquid for improving paper quality. 5. The anionic vinyl monomer (d) comprises unsaturated monocarboxylic acid, unsaturated dicarboxylic acid, unsaturated tricarboxylic acid, unsaturated tetracarboxylic acid, unsaturated sulfonic acid, unsaturated phosphonic acid and salts thereof. The surface paper quality improving liquid agent according to any one of claims 1 to 4, which is at least one selected from the group. 6. The surface paper quality improving liquid agent according to claim 1, wherein the resin (a) is a styrene-acrylic acid resin. 7. The surface paper quality improving liquid agent according to claim 1, wherein the acrylamides (c) are acrylamide and methacrylamide.