JP2001279158A - Binder for paper coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a novel binder for a paper coating material, that imparts the function of improving fluidity and of improving water retentivity, to obtain a paper coating material containing the binder, and to obtain coated papers, coated fiber boards, and coated functional papers prepared by using the same. SOLUTION: Provided are a binder for a paper coating material, comprising a copolymer made from (a) an ethylenically unsaturated carboxylic acid (salt), [the ethylenically unsaturated carboxylic acid (salt) means an ethylenically unsaturated carboxylic acid or an ethylenically unsaturated carboxylate, and the same shall apply hereinbelow], (b) (meth)acrylonitrile, and (c) other copolymerizable monomers, the copolymer containing (a), (b), and (c) in a ratio (a)/(b)/(c) of (60-95 parts by mass)/(5-40 parts by mass)/((0-10 parts by mass) and having a weight-average molecular weight of 10,000-2,000,000 and a paper coating material containing the same, and coated papers such as offset printing papers, gravure printing papers, and letterpress printing papers, coated fiber boards, and functional coated papers such as inkjet recording papers, no-carbon papers, thermal recording papers, magnetic recording papers, and electrostatic recording papers all of which are prepared by coating with the coating material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a binder for paper coating paint. More specifically, the present invention relates to a binder for a paper coating paint which imparts a fluidity improvement (a drastic increase in low shear viscosity and a low high shear viscosity) to the paper coating paint and a water retention improving function,
Paper coating containing the binder capable of imparting high operability, high physical properties of coated paper, and printability, and coated paper, coated paperboard and functional coated paper coated with the coating It is.

[0002]

2. Description of the Related Art Conventionally, synthetic latexes such as styrene butadiene latex, carboxyl-modified styrene butadiene latex, acrylic latex and ethylene vinyl acetate latex, starch, polyvinyl alcohol, methylcellulose, carboxymethylcellulose and the like have been known as binders for paper coating paints. Have been. In particular, from the viewpoint of quality and economics such as binder properties, coated paper and coated paperboard often use starch and styrene-butadiene latex in combination, and clear coat or functional coated paper often contains starch or polyvinyl alcohol. It is used. However, in recent years, demands for these coated papers, coated paperboards and functional coated papers have been further increased and the production amount has been increased, and it is necessary to improve operability such as increasing the coating speed. Further, due to the improvement in operability, the printing speed has been increased in accordance with each of these papers, and the level required for coated paper properties and printability has been increased. That is, none of the conventional known binders has performance that can follow the flow of these paper industry technologies, and there is no binder capable of realizing high operability, high coated paper physical properties and printability required by the industry. There was no drug. In response to these demands, to improve the flowability of the paper coating (to greatly increase the low shear viscosity and keep the high shear viscosity low) and to impart water retention,
Attempts to further improve the binder effect have been proposed.

For example, in a styrene-butadiene latex system, a large amount of a hydrophilic copolymer component is incorporated in order to increase the low shear viscosity of a paper coating composition, and the particle diameter and the particle size distribution are adjusted in order to keep the high shear viscosity low.
Various adjustments as described above for changing the type and amount of the copolymer components to increase the water retention of the paper coating paint, changing the polymerization method, and improving the binder properties for improving the coated paper properties and printability. However, increasing the viscosity of Rosia has lost balance with other functions, and there has been no satisfactory solution.

[0004] Further, instead of adjusting the latex itself, attempts have been made to add another water-soluble copolymer to the latex. For example, JP-A-60-224896 discloses that a polycarboxylate is added to latex for the purpose of improving the fluidity and water retention of a paper coating paint and the use thereof is used to improve the water retention of the paper coating paint. Although proposals have been made to improve the flow characteristics and the like, the Locia viscosity has not been sufficiently increased, and the improvement of the flowability and water retention in actual coating is not satisfactory. Furthermore, there is no description about the binder effect, nor is there any specific content of the polycarboxylate to be added.

Japanese Patent Application Laid-Open No. H11-106435 discloses a method for improving the dry pick strength and wet topic strength of a paper coated paper exhibiting a binder property of the paper coated paint. It has been proposed to add a water-soluble oligomer to latex and use it to improve the dry pick strength and wet topic strength of paper coated paper, but no improvement in dry pick strength and wet topic strength was observed. In addition, there is no description regarding a specific method for producing a water-soluble oligomer or the fluidity of a paper coating material, and it is not yet satisfactory.

On the other hand, water-soluble polymers having a high binder function, such as polyvinyl alcohol, methylcellulose and carboxymethylcellulose, are used as binders for special applications such as surface processing, but have poor fluidity. When used as a binder for paper coating paints mainly composed of a binder, they are hardly used because the high shear viscosity of the paper coating paint becomes extremely high and the fluidity deteriorates. Also,
Starch is used for reasons such as improving the water retention of paper-coated paints and obtaining the rigidity of paper-coated papers, but has the disadvantage of poor fluidity, especially high shear viscosity and high shear fluidity. .

Many attempts have been made to improve these properties. However, with conventional binders, the flowability of the paper coating composition is poor, and the flowability of the paper coating composition is improved. It is not possible to reduce the viscosity), to impart water retention, or to enhance the binder effect.

The fluidity improver for paper coating paints includes a thickener for paper coating paints, such as sodium alginate, carboxymethylcellulose, methylcellulose, and the like.
Ethyl cellulose and the like have been used, but in recent years, synthetic water retention agents having a water retention function have been widely used as thickening agents. With regard to synthetic water retention agents, the trend to increase the low shear viscosity by adding a small amount, suppress the increase in the high shear viscosity as much as possible, and add the water retention function to improve the operability of the paper coating and improve the quality of the paper coated paper Although there is no proposal for imparting a binder property.

[0009]

As described above, these conventional binders are not satisfactory with respect to improvements in quality such as high operability, high coated paper properties and printability. The present invention solves these problems by improving the fluidity of the paper coating paint (by greatly increasing the low shear viscosity and keeping the high shear viscosity low), and for imparting the water retention improving function to paper coating paints. An object of the present invention is to provide a binder, a paper coating paint containing the same, and a coated paper, a coated paperboard, and a functional coated paper coated with the paint.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, a binder having a specific composition has improved the fluidity of a paper coating paint (the viscosity of the paint has been greatly increased). The present invention has been found to have functions of imparting water retention and enhancing a binder effect, as well as functions of suppressing high shear viscosity).

That is, the present invention provides (a) an ethylenically unsaturated carboxylic acid (salt) [an ethylenically unsaturated carboxylic acid (salt) means an ethylenically unsaturated carboxylic acid or an ethylenically unsaturated carboxylic acid salt. same as below. ],
(B) a copolymer of (meth) acrylonitrile and (c) other copolymerizable monomers, (a)
(B) and (c) are (a) / (b) / (c) = 60-9
5% by mass / 5 to 40% by mass / 0 to 10% by mass and a weight average molecular weight of 10,000 to 2,000,000. Paper coating paint characterized by containing 0.01 to 15 parts by mass with respect to parts by mass, and coated paper such as offset printing paper, gravure printing paper, letterpress printing paper, etc., coated with the coating material. Paperboard, ink jet recording paper, carbonless paper, thermal recording paper, magnetic recording paper,
Functional coated paper such as electrostatic recording paper.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of the monomer (a) ethylenically unsaturated carboxylic acid (salt) used in the present invention include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and maleic anhydride. , Fumaric acid and salts thereof, and preferably at least one selected from acrylic acid, methacrylic acid, maleic acid and salts thereof. More preferred are acrylate, methacrylate and maleate. Salts include alkali metals (lithium, sodium,
At least one selected from the group consisting of salts such as potassium, salts of alkaline earth metals (such as calcium and magnesium), ammonium salts, and salts of organic amines (such as alkanolamines and lower alkylamines). As alkanolamines, monoethanolamine, diethanolamine,
Lower alkylamines such as triethanolamine and aminomethylpropanol include mono-, di- and trialkyl (C1-C4) amines.

Specific examples of (c) other copolymerizable monomers used in the present invention include (meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, and (meth) acrylic acid.
Alkyl (meth) acrylates such as propyl acrylate and butyl (meth) acrylate, polyoxyethylene (2 to 100 ethylene oxide addition moles) (meth) acrylic monoester, polyoxyethylene propylene (alkylene oxide) (Addition mole number 2 to 100) (meth) acrylic acid monoester, polyoxypropylene (propylene oxide addition mole number 2)
-100) polyoxyalkylenes such as (meth) acrylic acid monoesters (addition of 2 moles of alkylene oxide)
100) (Meth) acrylic acid monoester, methoxy polyalkylene glycol (alkylene oxide added mole number 2 to 100) (meth) acrylic acid ester, ethoxy polyalkylene glycol (alkylene oxide added mole number 2 to 100) (meth) acrylic acid Alkoxy polyalkylene glycols such as esters, propoxy polyalkylene glycol (alkylene oxide addition moles 2 to 100) (meth) acrylate, butoxypolyalkylene glycol (alkylene oxide addition moles 2 to 100) (meth) acrylate Alkylene oxide addition mole number 2-100) (meth) acrylate, polyoxyethylene (ethylene oxide addition mole number 2-100) monovinyl ether, polyoxyethylene propylene Alkylene oxide addition mole number 2
100) monovinyl ether, polyoxypropylene (polypropylene oxide addition mole number 2 to 100) polyoxyalkylene (alkylene oxide addition mole number 2 to 100) monovinyl ether such as monovinyl ether, methoxypolyalkylene glycol (alkylene oxide addition mole number 2 to 2) 100) Monovinyl ether, ethoxy polyalkylene glycol (alkylene oxide addition mole number 2 to 100) monovinyl ether, propoxy polyalkylene glycol (alkylene oxide addition mole number 2 to 100) monovinyl ether, butoxypolyalkylene glycol (alkylene oxide addition mole 2 ~ 1
00) Alkoxypolyalkylene glycols such as monovinyl ether (alkylene oxide addition mole number 2-1)
00) monovinyl ether, polyoxyethylene (ethylene oxide addition mole number 2 to 100) allyl ether,
Polyoxyethylene propylene (alkylene oxide addition mole number 2 to 100) allyl ether, polyoxypropylene (propylene oxide addition mole number 2 to 100)
Allyl ethers and other polyoxyalkylenes (alkylene oxide addition moles 2 to 100) allyl ethers, methoxy polyalkylene glycols (alkylene oxide addition moles 2 to 100) allyl ethers, ethoxy polyalkylene glycols (alkylene oxide addition moles 2 to 100) ) Allyl ether, propoxypolyalkylene glycol (alkylene oxide addition mole number 2 to 10)
0) Allyl ether, butoxy polyalkylene glycol (alkylene oxide added mole number 2 to 100) alkoxypolyalkylene glycol (alkylene oxide added mole number 2 to 100) allyl ether such as allyl ether, hydroxymethyl (meth) acrylate, (meth) Hydroxyalkyl (meth) acrylates such as hydroxyethyl acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate,
Amide compounds such as (meth) acrylamide, N, N'-dimethylacrylamide, N-alkanol (meth) acrylamide, dimethylaminomethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminomethyl (meth) acrylate, Diethylaminoethyl (meth) acrylate, vinyl acetate, vinyl chloride,
From the group consisting of styrene, vinyltoluene, benzyl (meth) acrylate, styrenesulfonic acid (salt), vinylsulfonic acid (salt), 2-acrylamido-2-methylpropanesulfonic acid (salt), vinylpyridine and salts thereof One or more selected ones can be used. The salt is one selected from the group consisting of alkali metal (such as lithium, sodium, and potassium) salts, alkaline earth metal (such as calcium and magnesium) salts, ammonium salts, and organic amine (such as alkanolamines and lower alkylamines) salts. That is all. Alkanolamines include monoethanolamine, diethanolamine, triethanolamine, aminomethylpropanol and the like, and lower alkylamines include mono, di, trialkyl (C1 to C1).
C4) amines and the like.

In the binder for paper coating composition of the present invention, (a) an ethylenically unsaturated carboxylic acid (salt), (b)
The ratio of (meth) acrylonitrile and (c) other copolymerizable monomers is 100 parts by mass of the total monomers,
(A) is 60 to 95 parts by mass, (b) is 5 to 40 parts by mass, and (c) is 0 to 10 parts by mass. Preferably (a)
Is 65 to 90 parts by mass, (b) is 10 to 35 parts by mass, and (c) is 0 to 5 parts by mass. If (a) is less than 60 parts by mass, the effect of improving the fluidity of the paper coating composition is reduced (the rise in low shear viscosity is small), and the effect of imparting water retention is also reduced. When the amount exceeds 95 parts by mass, the effect of imparting the binder property of the paper coating composition is reduced. When (b) is less than 5 parts by mass, the effect of imparting the binder property of the paper coating composition is reduced. 4
If the amount exceeds 0 parts by mass, the effect of improving the fluidity of the paper coating composition is reduced (the rise in the viscosity of the low shear is small), and the effect of imparting water retention is also reduced.

The binder for a paper coating composition of the present invention contains a copolymer having a weight average molecular weight of 10,000 to 2,000,000. Preferably 50,000 to 2,0
It contains a copolymer consisting of 0.00000. When the weight-average molecular weight is less than 10,000, the effect of imparting the binder property of the paper coating composition decreases, and a large amount of the binder is required. In addition, the effect of improving the fluidity of the paper coating composition is reduced (the rise in low shear viscosity is small), and the effect of imparting water retention is also reduced. On the other hand, when it exceeds 2,000,000, the effect of imparting the binder property of the paper coating composition is high, and the low shear viscosity, which is an effect of improving the flowability of the paper coating composition, is high and good, but the high shear viscosity is high. It is difficult to speed up the application of the paper coating paint, and it is necessary to lower the concentration of the paper coating paint.

Regarding the fluidity improving effect, when the weight average molecular weight is 10,000 to 30,000, no thickening effect can be expected, and the weight average molecular weight exceeds 500,000, and especially 70,000 to 2,000,000. In the case of 000, a thickening effect is exhibited.

The binder for a paper coating composition of the present invention contains a copolymer, and the copolymer may be used alone or in a mixture.

The weight average molecular weight in the present invention can be measured by gel permeation chromatography (GPC) using polyethylene glycol of a known molecular weight as a standard substance. The weight average molecular weight was measured under the following conditions using gel permeation chromatography (GPC) of model HLC-8120GPC manufactured by Tosoh Corporation. Tosoh Corporation, model G5000PWXL and model G3000PWXL were used for the column.
The column temperature was 40 ° C, the detector was an RI detector, 0.1-MPB disodium hydrogen phosphate and sodium dihydrogen phosphate aqueous solution were used as eluent, and the flow rate was 0.6 ml / mi.
n., sample concentration is 0.4%, sample solution injection volume is 50 μl,
The data processor is manufactured by Tosoh Corporation, model SC-8020,
TSK standard polyethylene oxide (SE-150: weight average molecular weight 885,000, SE, manufactured by Tosoh Corporation) as a standard substance of polyethylene glycol having a known molecular weight.
-70: weight average molecular weight 510,000, SE-30:
Weight average molecular weight 340,000, SE-15: weight average molecular weight 170,000, SE-8: weight average molecular weight 9
5,000, SE-5: weight average molecular weight 46,000,
SE-2: Weight average molecular weight 26,000), Wako Pure Chemical Industries, Ltd., Wako Standard Class 1 approved polyethylene glycol 6000: Weight average molecular weight 7,500, Wako Pure Chemical Industries, Ltd., reagent grade ethylene glycol: A weight average molecular weight of 62 was used.

The method for producing the binder for a paper coating composition of the present invention can be carried out by using a known solution polymerization in general, and is not limited at all. For example, in solution polymerization,
(A) ethylenically unsaturated carboxylic acid (salt), (b) (meth) acrylonitrile and (c) other copolymerizable monomers in the presence of a usual polymerization initiator, water or / and alcohol-based ( In a solvent such as methanol, ethanol and isopropyl alcohol) at 40-130 ° C.
After polymerization for 1 to 15 hours, it can be easily obtained by neutralizing with a base, if necessary. With respect to acidic groups such as ethylenically unsaturated carboxylic acids, if necessary, a method of partially or wholly neutralizing a base with a base before, during and after polymerization is also possible. The polymerization method includes (a) an ethylenically unsaturated carboxylic acid (salt),
(B) The total amount of (meth) acrylonitrile and (c) other copolymerizable monomers may be charged into a polymerization tank for polymerization, or may be charged dropwise and polymerized. Further, a part of the monomers may be charged into the polymerization tank and the polymerization may be performed while dropping some of the monomers. The polymerization initiator may be charged in its entirety in a polymerization tank for polymerization, or may be charged dropwise and polymerized. The solvent may be a combination of water and an alcohol, or may be used in combination at any ratio. Further, the entire amount of the solvent may be charged into the polymerization tank for polymerization, or may be charged while dropping or polymerization may be performed. on the other hand,
The polymerization may be performed while charging the entire amount of the solvent into the polymerization tank and removing the solvent during the polymerization.

Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile, 4,4'-azobis-4-cyanovaleric acid, and 2,2'-azobis (4-methoxy-2,
4-dimethylvaleronitrile, 2,2′-azobis (2
-Methylbutyronitrile), 1,1'-azobis (cyclohexane-1-alkonitrile), 2,2'-azobis (2,4,4-trimethylpentane), dimethyl 2,
2′-azobis (2-methylpropionate), 2,
2′-azobis [2- (hydroxymethyl) propionitrile] and 1,1′-azobis (1-acetoxy-
Azo catalysts such as 1-phenylethane), inorganic peroxides such as ammonium persulfate, perborate and hydrogen peroxide, redox catalysts such as ascorbic acid-hydrogen peroxide, and organic peroxides such as benzoyl peroxide. Is raised.
One or more selected from these can be used.
Preferably, 2,2'-azobisisobutyronitrile,
4,4′-azobis-4-cyanovaleric acid, 2,2 ′
-Azobis (4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-alkonitrile), 2,2'- Azobis (2,4,4-trimethylpentane), dimethyl 2,2′-azobis (2-
Methylpropionate), 2,2′-azobis [2-
(Hydroxymethyl) propionitrile] and 1,
An azo catalyst such as 1′-azobis (1-acetoxy-1-phenylethane) is exemplified.

The binder for paper coating paint of the present invention is effective for coated paper such as offset printing paper, gravure printing paper, letterpress printing paper and the like, coated paperboard, ink jet recording paper, carbonless paper, and thermal recording. Effective for paper coatings for functional coated papers such as paper, magnetic recording paper, electrostatic recording paper, etc., improves fluidity, imparts water retention and binder properties of paper coatings mainly composed of pigments and binders It is effective for application and particularly effective as a binder for paper coating paint. Specifically, the binder for paper coating paint of the present invention,
It has the function of increasing the low shear viscosity of paper coatings and suppressing the high shear viscosity, that is, improving the fluidity while uniformly dispersing pigments and binders. It also has a function to enhance the binder application effect, and can be expected to improve operability, is suitable for high-speed coating of paper coating paint, which is a technical trend in the papermaking industry, and improves dry pick strength of offset printing paper It is most suitable for improving the strength of wet picks, gravure printing paper and various functional papers. Further, it is also effective for improving the functionality such as imparting the stiffness of the paper. The binder for paper coating paint of the present invention has a high binder imparting effect to the paper coating paint, and the binder effect is clearly improved, so that it is possible to reduce the amount of the conventional binder used, It is also possible to use it in combination. Further, since it has a high effect of imparting water retention to the paper coating paint, it can be used as a water retention agent having both a binder function and a fluidity improving function, and can also be used by mixing with a synthetic water retention agent.

Examples of pigments in these paper coatings include inorganic pigments such as clay, calcium carbonate, silica, silica gel, titanium oxide, satin white, barium sulfate, talc, zinc oxide, gypsum, and polystyrene-based plastic pigments. Organic pigments are used, and they are used alone or in combination.

Conventional binders used in combination with these paper coating paints include natural binders such as starch, modified starch, casein, modified soy protein, styrene butadiene latex, carboxyl modified styrene butadiene latex, acrylic latex, and ethylene vinegar. Bi latex, vinyl acetate resin emulsion, vinyl chloride resin emulsion, acrylic styrene resin emulsion, silicone resin emulsion, urethane resin emulsion, epoxy resin emulsion, fluororesin emulsion, ABS latex, NBR latex, CR latex, polyvinyl alcohol, Synthetic binders such as methylcellulose and carboxycellulose are exemplified.

Since the binder for paper coating composition of the present invention is water-soluble, it can be added to the paper coating composition as it is under stirring. In addition, before addition to the paper coating paint, it can be added to the water retention fluidity improver or latex for the paper coating paint under stirring in the same manner,
Each can be used as a binder for paper coating paints.

The binder for a paper coating composition of the present invention comprises a dispersant, a water-retaining agent, a defoaming agent, a lubricant, a water-proofing agent, a wetting agent, a preservative and fungicide, an antioxidant, an ultraviolet absorber, and a deodorant. And various binders such as fragrances, dyes and pigments and latex may be contained or mixed for use.

The copolymer of the present invention can also contain a nonionic surfactant. Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, fatty acid polyethylene glycol esters, ethylene oxide adducts of partial fatty acid esters of polyhydric alcohols, fatty acid amide ethylene oxide adducts, and ethylene oxide / propylene oxide copolymers. Polyoxyethylene-type nonionic surfactants and fatty acid esters of glycerin,
Examples include polyhydric alcohol type nonionic surfactants such as sorbitol fatty acid ester, sorbitan fatty acid ester, polyhydric alcohol alkyl ether and alkanolamine fatty acid amide. Among these, preferred are polyoxyethylene (2 to 100 ethylene oxide addition moles) octyl phenyl ether,
Polyoxyethylene (2 to 2 moles of ethylene oxide added)
100) nonylphenyl ether and polyoxyethylene (2 to 100 moles of ethylene oxide added) alkyl (6 to 22 carbon atoms) ether and ethylene oxide (2 to 100 moles of ethylene oxide added) · propylene oxide (2 to 10 moles of propylene oxide added)
0) Polyoxyethylene-type nonionic surfactants such as copolymers, more preferably polyoxyethylene (2 to 50 moles of ethylene oxide added) octylphenyl ether, polyoxyethylene (2 to 50 moles of ethylene oxide added) Nonylphenyl ether, polyoxyethylene (2 to 50 moles of ethylene oxide added)
Alkyl (C18-C18) ether and ethylene oxide (ethylene oxide addition mole number 2-50) propylene oxide (propylene oxide addition mole number 2-5)
0) Copolymers and the like. One selected from these groups and / or a mixture of two or more may be used.
If necessary, an anionic surfactant can be used in combination. Preferably, one selected from the group consisting of polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether phosphate and polyoxyethylene alkyl ether phosphate, and And / or two or more anionic surfactants.

The amount of the nonionic surfactant to be used is 1 to 30 parts by mass, preferably 3 to 25 parts by mass, more preferably 5 to 20 parts by mass based on 100 parts by mass of the copolymer. If the amount of the nonionic surfactant used is less than 1 part by mass, the adhesion of the paper coating paint to the coated paper cannot be expected to be improved by the nonionic surfactant. The effect of imparting a binder property is reduced, the water retention of the paper coating composition is reduced, and the foam of the paper coating composition is undesirably increased.

When the binder for a paper coating composition of the present invention is used as a binder for a paper coating composition containing a pigment and a binder as a main component, the amount of the binder for a paper coating composition of the present invention (in terms of solid content) is as follows. It is usually 0.01 to 15 parts by mass, preferably 0.05 to 13 parts by mass, more preferably 0.1 to 1 part by mass, based on 100 parts by mass of the pigment in the paper coating composition.
2 parts by mass. If the amount is less than 0.01 part by mass, the effect of imparting binder properties, the effect of imparting water retention and the effect of improving fluidity of the paper coating composition are not exhibited, and if the amount exceeds 15 parts by mass, the effect of imparting binder properties and effect of imparting water retention are high and good. However, the fluidity improving effect, especially the viscosity of the low shear and the high shear, is undesirably too high.

The paper coating composition using the binder for paper coating composition of the present invention is usually used in the form of an aqueous dispersion, and if necessary, other additives such as a dispersant such as sodium polyacrylate; Polyacrylic copolymers, sodium alginate, carboxymethylcellulose, hydroxyethylcellulose, water retention agents such as methylcellulose, ethylcellulose, polyvinyl alcohol, etc., defoamers such as fatty acid esters, lubricants such as calcium stearate, glyoxal and urea resins or polyamide polyamines Water-proofing agents such as resins, wetting agents, preservatives and fluorescent dyes are added. Binders other than the paper coating paint binder of the present invention, for example, starch, modified starch, casein, natural binders such as modified soy protein and styrene butadiene latex, carboxyl modified styrene butadiene latex, acrylic latex, ethylene vinyl acetate latex, Vinyl acetate resin emulsion, vinyl chloride resin emulsion, acrylic styrene resin emulsion, silicone resin emulsion, urethane resin emulsion, epoxy resin emulsion, fluororesin emulsion, ABS latex, NBR latex, CR latex, polyvinyl alcohol, methylcellulose, carboxycellulose Synthetic binders and the like are used.

The paper coating composition can be applied to the paper by a known method, for example, with an air knife coater, curtain flow coater, blade coater, roll coater, rod coater, size press coater, or the like. After coating, it is dried and finished with a calender ring or super calender ring as required. The coating temperature is usually 10 to 60 ° C, the drying temperature is usually 90 to 150 ° C, and the temperature of the calender ring, super calender ring or soft nip calender ring is usually 30 to 200.
° C.

[0031]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the following examples, “parts” means “parts by mass” and “%” means “% by mass”.

Example 1 299.7 parts of water was charged into a glass reaction vessel equipped with a dropping funnel, a reflux condenser, a stirrer, and a thermometer.
１００100 ° C., and 251.6 acrylic acid under stirring.
Parts, methacrylic acid 31.4 parts, acrylonitrile 28.
0 parts of the mixed monomer solution and a 5% aqueous solution of sodium persulfate were added dropwise from a dropping funnel at a constant rate over 3 hours to carry out polymerization. The reaction temperature was kept at 60-100C.
After maintaining the same temperature for 3 hours after the completion of dropping (referred to as aging), 4
The mixture was cooled to 0 ° C., neutralized with 308.1 parts of a 50% aqueous sodium hydroxide solution, and was a copolymer consisting of 83 parts by mass of sodium acrylate / 10 parts by mass of sodium methacrylate / 7 parts by mass of acrylonitrile. 000 paper binders were obtained.

Example 2 376.3 parts of water and 500.0 parts of isopropyl alcohol were charged into a glass reaction vessel equipped with a dropping funnel, a reflux condenser, a stirrer and a thermometer, and the temperature was raised to 60 to 90 ° C., followed by stirring. Below, a mixed monomer solution of 151.7 parts of acrylic acid, 40.0 parts of acrylonitrile, and 40.0 parts of methacrylonitrile, and a 1% aqueous solution of ammonium persulfate were respectively dropped from a dropping funnel at a constant rate over 3 hours to carry out polymerization. The reaction temperature was maintained at 60-90C. After dropping 3
After maintaining the same temperature for a period of time (aging), isopropyl alcohol was distilled off, 1008.2 parts of water was charged, the mixture was cooled to 40 ° C, and neutralized with 168.5 parts of a 50% aqueous sodium hydroxide solution.
Sodium acrylate 80 parts by mass / acrylonitrile 1
A binder for a paper coating material having a weight average molecular weight of 872,000 was obtained from a copolymer consisting of 0 parts by mass / 10 parts by mass of methacrylonitrile.

Example 3 In the same manner as in Example 1, water 1 was added to a glass reaction vessel.
81.0 parts were charged, and the temperature was increased to 60 to 100 ° C.
Under stirring, 203.9 parts of acrylic acid, acrylonitrile 1
48.0 parts of the mixed monomer solution and 281.5 parts of a 1% aqueous solution of ammonium persulfate were added dropwise from a dropping funnel at a constant rate over 3 hours to carry out polymerization. Reaction temperature is 60
１００100 ° C. was maintained. After maintaining the same temperature for 3 hours after the completion of dropping (aging), 1007.0 parts of water was charged, cooled to 40 ° C, and neutralized with 192.6 parts of a 25% aqueous ammonia solution.
A copolymer consisting of 63 parts by mass of ammonium acrylate / 37 parts by mass of acrylonitrile, having a weight average molecular weight of 77,
000 paper binders were obtained.

Example 4 In the same manner as in Example 2, water 4 was added to a glass reaction vessel.
55.3 parts, 455.3 parts of isopropyl alcohol, and 1.1 parts of 2,2′-azobisisobutyronitrile were charged, the temperature was raised to 60 to 80 ° C., and 148.3 methacrylic acid was stirred. Parts, 60.6 parts of acrylic acid, and 33.0 parts of acrylonitrile were dropped at a constant rate over a period of 5 hours from a dropping funnel of a mixed monomer solution to carry out polymerization. The reaction temperature was maintained at 60-80 ° C. After maintaining the same temperature for 3 hours after completion of dropping (aging), isopropyl alcohol was distilled off.
1002.7 parts of water was charged, cooled to 40 ° C., neutralized with 205.4 parts of a 50% aqueous solution of caustic soda, and a mixture consisting of 47 parts by weight of sodium methacrylate / 20 parts by weight of sodium acrylate / 33 parts by weight of acrylonitrile. United,
A binder for paper coating paint having a weight average molecular weight of 1,430,000 was obtained.

Example 5 In the same manner as in Example 2, water 5 was added to a glass reaction vessel.
58.3 parts and 55.8 parts of isopropyl alcohol were charged, and 4,4'-azobis-4-cyanovaleric acid 1.2
Of acrylic acid, 264.6 parts of acrylonitrile and 100.0 parts of acrylonitrile under stirring.
And a mixed monomer solution of 20.0 parts of polyoxyethylene glycol (20 moles of ethylene oxide added) acrylic acid monoester was dropped from the dropping funnel at a constant speed over 5 hours to polymerize. The reaction temperature was maintained at 60-80 ° C. After the completion of the dropwise addition, the mixture was maintained at the same temperature for 3 hours (aging), and 55.8 parts of isopropyl alcohol was distilled off.
Charge 3.0 parts, cool to 40 ° C.
Neutralized with 8.9 parts, lithium acrylate 50 parts by mass /
20 parts by mass of acrylic acid / 25 parts by mass of acrylonitrile /
Polyoxyethylene glycol (ethylene oxide 20
(Mole adduct) A binder for paper coating paint having a weight average molecular weight of 1,920,000 was obtained from a copolymer comprising 5.0 parts by mass of acrylic acid monoester.

Example 6 In the same manner as in Example 2, water 2 was added to a glass reaction vessel.
41.5 parts, 563.5 parts of isopropyl alcohol were charged, the temperature was raised to 60 to 90 ° C., and a mixed monomer of 227.4 parts of acrylic acid, 68.0 parts of acrylonitrile, and 28.8 parts of styrenesulfonic acid was stirred. The solution and 194.4 parts of a 3% aqueous solution of ammonium persulfate were added dropwise from a dropping funnel at a constant rate over 3 hours to carry out polymerization. The reaction temperature was maintained at 60-90C. After the completion of the dropwise addition, the mixture was kept at the same temperature for 3 hours (aging), isopropyl alcohol was distilled off, the mixture was cooled to 40 ° C., neutralized with 265.1 parts of 50% sodium hydroxide, and 75 parts by mass of sodium acrylate / acrylonitrile 17 Parts by mass / sodium styrene sulfonate 8
A copolymer consisting of parts by mass and having a weight average molecular weight of 19,00
0 was obtained for a binder for paper coating.

Example 7 The binder for the paper coating material obtained in Example 4 1000.
To 0 parts, 100.0 parts of a 20% aqueous solution of polyoxyethylene (12 mol adduct of ethylene oxide) dioctyl ether was added to obtain a binder for paper coating paint.

Comparative Example 1 A glass reaction vessel equipped with a dropping funnel, a reflux condenser, a stirrer, and a thermometer was charged with 505.1 parts of water and heated at a temperature of 60%.
To 100 ° C., and while stirring, a mixed monomer solution of 71.7 parts of acrylic acid and 65.9 parts of methacrylic acid was added to 0.5 wt.
96.3 parts of a 10% aqueous solution of ammonium persulfate were added dropwise from a dropping funnel at a constant rate over 3 hours to carry out polymerization. The reaction temperature was kept at 60-100C. After dropping 3
After maintaining the same temperature for a period of time (aging), 1001.5 parts of water was charged, cooled to 40 ° C, and triethanolamine 262.
Neutralize with 5 parts and triethanolamine acrylate 55
A copolymer comprising parts by mass / 45 parts by mass of triethanolamine ammonium methacrylate, having a weight average molecular weight of 1,
090,000 binders for paper coatings were obtained.

Comparative Example 2 In the same manner as in Comparative Example 1, water 2 was added to a glass reaction vessel.
76.8 parts were charged, and the temperature was increased to 60 to 100 ° C.
Under stirring, a mixed monomer solution of 297.1 parts of acrylic acid and 8.0 parts of methacrylonitrile and 109.8 parts of a 5% aqueous solution of sodium persulfate were added dropwise from a dropping funnel at a constant rate over 3 hours to carry out polymerization. . Reaction temperature is 60-1
The temperature was kept at 00 ° C. After the dropping was completed, the temperature was maintained for 3 hours (aging), cooled to 40 ° C., and a 50% aqueous sodium hydroxide solution 3 was added.
Neutralized with 30.1 parts, a copolymer consisting of 98 parts by weight of sodium acrylate / 2 parts by weight of methacrylonitrile,
A binder for paper coating paint having a weight average molecular weight of 73,000 was obtained.

Comparative Example 3 A flask having a capacity of 1 liter was charged with 60 parts of itaconic acid, 35 parts of acrylonitrile, 5 parts of 2-hydroxyethyl acrylate, 900 parts of water and 0.1 part of sodium hydroxide, and nitrogen gas was introduced. While stirring, the temperature in the system was raised to 80 ° C. Next, sodium peroxodisulfate 1
0 parts were added to the system, and stirring was continued at 80 ° C. for 5 hours.
Thereafter, the mixture was cooled to room temperature to obtain a water-soluble oligomer. The weight average molecular weight was 7,700. (This binder was prepared according to the invention (Example 1) of JP-A-11-106435.)

Comparative Example 4 A glass-made reaction vessel equipped with a dropping funnel, a reflux condenser, a stirrer and a thermometer was charged with 349.5 water and 700.0 parts of isopropyl alcohol, heated to a temperature of 60 to 90 ° C., and stirred. , Acrylic acid 171.5 parts, methacrylic acid 3
3.4 parts, 120.0 parts of acrylonitrile, 8.0 parts of acrylic acid methyl ester, 20.0 parts of hydroxyethyl methacrylate, and 352.9 parts of a 10% ammonium persulfate aqueous solution were each added by a dropping funnel to 3 parts.
It was dropped at a constant rate over time and polymerized. The reaction temperature was maintained at 60-90C. After the completion of the dropwise addition, the mixture was kept at the same temperature for 3 hours (aging), and isopropyl alcohol was distilled off.
Cooled to 18 ° C., neutralized with 188.4 parts of a 25% aqueous ammonia solution, 53 parts by weight of ammonium acrylate / 10 parts by weight of ammonium methacrylate / 30 parts by weight of acrylonitrile / 2 parts by weight of methyl acrylate / hydroxyethyl methacrylate A binder for a paper coating composition having a weight average molecular weight of 8,900 was obtained from a copolymer consisting of 5 parts by mass.

Comparative Example 5 In the same manner as in Comparative Example 1, water 2 was added to a glass reaction vessel.
84.4 parts were charged, and the temperature was raised to 60 to 100 ° C.
Under stirring, 212.2 parts of acrylic acid and 31.
6 parts, a mixed monomer solution of 80.0 parts of methacrylonitrile and 129.5 parts of a 1% aqueous solution of sodium persulfate were added dropwise from a dropping funnel at a constant rate over 3 hours to carry out polymerization. The reaction temperature was kept at 60-100C. After the completion of the dropwise addition, the temperature was maintained for 3 hours (aging), 1003.3 parts of water was charged, the mixture was cooled to 40 ° C., and a 50% aqueous sodium hydroxide solution 2 was added.
Neutralized with 65.1 parts, a binder composed of 70 parts by weight of sodium acrylate / 10 parts by weight of sodium methacrylate / 20 parts by weight of acrylonitrile and having a weight average molecular weight of 2,330,000 for paper coating paint I got

Comparative Example 6 The binder for paper coating paint 1000 obtained in Example 4.
0 parts of polyoxyethylene (25 mol ethylene oxide adduct) lauryl ether sulfate sodium salt 2
100.0 parts of a 0% aqueous solution was added to obtain a binder for paper coating paint.

Comparative Example 7 Sodium alginate (Kimitsu Algin L manufactured by Kimitsu Kasei Co., Ltd.)
A 5% aqueous solution of -2) was prepared to obtain a binder for paper coating paint.

Comparative Example 8 A 5% aqueous solution of carboxymethylcellulose (Cerogen PR manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was prepared to obtain a binder for paper coating paint.

Comparative Example 9 Hydroxyethyl cellulose (manufactured by Daicel Chemical Industries, Ltd.
P-800) was prepared to obtain a binder for paper coating paint.

Comparative Example 10 A binder for a paper coating material was obtained using a styrene-butadiene-based latex (JSR0696, manufactured by JSR Corporation).

The compositions and weight average molecular weights of the compounds of Examples 1 to 7 and Comparative Examples 1 to 10 are shown in Table 1.

[0050]

[Table 1]

The performances of Examples 1 to 7 and Comparative Examples 1 to 10 were evaluated by the following methods. The results are shown in Table 2.

[0052]

[Table 2]

Evaluation Example 1 (1) Formulation of paper coating composition (parts: in terms of solid content, meaning parts by mass) 1 Pre-dispersed clay [ENGELHARD MINERA
70 parts of L & CHEMICALS, Ultra White 90], heavy calcium carbonate (FMT-FMT, FMT-
90] 15 parts, light calcium carbonate [Okutama Industry Co., Ltd.
Tamapearl TP-222-HS], 15 parts, dispersant [San Nopco Co., Ltd., SN Dispersant 504]
0] 0.2 part, sodium hydroxide 0.1-0.3 part, phosphoric acid-modified starch [manufactured by Japan Food Processing Co., Ltd., MS-4600]
3 parts, SBR latex [JSR0696, manufactured by JSR Corporation] 9 parts, lubricant [San Nopco Co., Ltd.]
Co., Ltd., 1 part of Nopcoat C-104-HS] and 3 parts of a binder for paper coating paint to prepare a paper coating paint having a pH of 9.0 and a paper coating paint concentration of 63%.

(2) Paper coating physical properties Low shear viscosity: BM type viscometer manufactured by Tokyo Keiki Co., Ltd., 60 rp
m, measured at 25 ° C. The higher the viscosity, the better. However, too high is not preferable. High shear viscosity: Hercules viscometer manufactured by Kumagai Riki, 880
Measured at 0 rpm and 25 ° C. The lower the viscosity, the better. Water retention: Caltech Scientific Co., Ltd.
Gravimetric water retention meter, pressure 0.5 kg / m ² , pressurization time 30 seconds. A smaller numerical value is preferable. Coated paper physical properties: A paper coating paint having a paper coating paint concentration of 63% was applied at a coating speed of 1,500 m / min with a CLC-6000 manufactured by Waferuser and dried. White paper gloss: The coated paper of the laydown 10 gr / m ² using a super calender, 60 ° C., after two paper feeding at a linear pressure of 80 Kg / cm,
It was conditioned and measured. Printing gloss, binder properties (dry pick strength, wet pick strength), water-absorbing ink deposition: Mei Seisakusho RI-
Printed with a 1-type printability tester. Binder property (dry pick strength, wet pick strength), water-absorbing ink adhesion property is 5
It was evaluated by the point method. The higher the value, the better. Smoothness: Measured by Oken type smoothness tester. The larger the value, the higher the smoothness and the better.

[0055]

When the binder for a paper coating composition of the present invention is used in a paper coating composition containing a pigment and a binder as a main component, the rheological viscosity and the flowability of a high shear viscosity at a shear rate of 10 ⁶ / sec or more can be improved. In addition, it has an effect which has not been known so far, that it has excellent binder properties. The paper coating binder of the present invention is also excellent in coating suitability,
It is possible to adjust a paper coating material having physical properties suitable for high-speed coating. Furthermore, the binder for paper coating paint of the present invention has improved dry pick strength due to the adhesiveness between pigments, the adhesiveness between pigment coated papers, the adhesiveness between pigment latexes, and the adhesiveness between latexes based on the binder imparting function. It has the effects of improving wet topic strength, suppressing latex migration, lowering blade pressure based on the function of lowering viscosity under high shear, and promoting immobilization of coating paint by increasing the low shear viscosity of paper coating paint. It is possible to form a uniform strong coating layer without coating unevenness,
The stiffness of the paper can be strengthened, and a smooth coated paper with excellent white paper gloss, printed gloss and water absorbing ink can be obtained.

Due to the above effects, the paper coating paint binder of the present invention is used in the papermaking industry in view of improving productivity, quality improvement, cost reduction, and energy saving in the production of coated paper. Achieving high-speed coating of water-based paper coating paint, which is a trend, can provide good coating paint physical properties, high operability and high coated paper physical properties, printability, and is suitable for the production of coated paper. is there.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J038 CC022 CE052 CF022 CG031 CG071 CG101 CG111 CG142 CG162 CG171 CG172 CH052 CH122 CH142 HA216 HA286 HA376 HA446 HA456 HA526 HA536 KA08 LA06 MA08 MA09 MA14 MA15 NA06 NA23 PA07 PB11 AG374AG BE08 EA30 FA12 FA13 FA14 GA15

Claims (4)

[Claims] (1) (a) ethylenically unsaturated carboxylic acid (salt), (b) (meth) acrylonitrile and (c)
Consisting of a copolymer of other copolymerizable monomers,
(A), (b), (c) are (a) / (b) / (c) =
60 to 95 parts by mass / 5 to 40 parts by mass / 0 to 10 parts by mass and a weight average molecular weight of 10,000 to 2,000,000
A binder for paper coating paint, which is 0. 2. A weight average molecular weight of 50,000 to 2.0.
The binder for paper coating paint according to claim 1, wherein the binder is 0.00000. 3. The binder for paper coating composition according to claim 1 or 2, wherein the binder is 0.01 to 15 parts by mass based on 100 parts by mass of the pigment.
A paper coating composition characterized by containing by mass. 4. Coated paper, coated paperboard or functional coated paper, coated with the paper coating composition according to claim 3.