JPH07157518A - Copolymer latex - Google Patents

Abstract

PURPOSE:To obtain a copolymer latex having excellent handleability, coating workability, solvent resistance, etc., and useful for coating by carrying out emulsion polymerization of an ethylenic unsaturated monomer having a specific group and an alkyl (meth)acrylate monomer in the presence of a specific amount of starch. CONSTITUTION:This latex is produced by the emulsion polymerization of (A) 100 pts.wt. of monomers consisting of (i) 10-60 pts.wt. of an ethylenic unsaturated monomer having cyano group, (ii) 10-60 pts.wt. of an ethylenic unsaturated monomer having hydroxyl group, (iii) 10-80 pts.wt. of an alkyl (meth)acrylate monomer and (iv) 0-20 pts.wt. of other ethylenic unsaturated monomer in the presence of (B) 5-200 pts.wt. of starch. Preferably, the component (i) is (meth) acrylonitrile, the component (ii) is 2-hydroxyethyl (meth)acrylate, the component (iii) is methyl (meth)acrylate, etc., and the component (iv) is ethylenic unsaturated acid monomer, aromatic vinyl monomer, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copolymer latex, more specifically, a copolymer which has good handleability and coating workability, and provides a coating surface excellent in solvent resistance, blocking resistance and the like. Regarding latex.

[0002]

2. Description of the Related Art Conventionally, paper has been used in a large amount in a wide range of fields for both consumer use and industrial use. Nowadays, paper or a substrate similar to paper is not used as it is, but is suitable. It is often used in practice as so-called processed paper that has been treated. And, in such a processed paper, a barrier layer having a property of not permeating various solvents or a property of not being attacked by the solvent, that is, "solvent resistance" is often required. For example, when producing release paper, the release agent used is often solvent-based, and the coating material used to form the barrier layer is
It is necessary to have sufficient solvent resistance in order to achieve the desired effect with a small amount of coating. Therefore, in the case of producing a release paper, a method in which polyethylene is laminated as an undercoat on a paper base material and a release agent is applied on the polyethylene is the mainstream. However, an undercoat made of polyethylene certainly has good solvent resistance as a barrier layer, but it is difficult to disintegrate such processed paper, so it is recommended to reuse it from the viewpoint of environmental protection and resource utilization. However, there is also a problem in that separate collection is required for recycling, resulting in an increase in treatment cost. On the other hand, in order to solve the problem of such an undercoat made of polyethylene, a method of using starch or a derivative thereof as a coating material (for example, JP-A-60-
No. 110999), a water-soluble copolymer, for example, a copolymer containing a hydrophilic monomer such as ethylenically unsaturated carboxylic acid or its hydroxyalkyl ester and a (meth) acrylic acid alkyl ester as main components is used. Method (for example, JP-A-1-156598, JP-B-5-517)
No. 20) and the like have been proposed. However, in these methods, the solvent resistance as a barrier layer is not sufficient, and since the glass transition point of the water-soluble copolymer is low, there is stickiness and blocking is likely to occur. There are drawbacks.

[0003]

Therefore, the present invention provides an undercoat for release paper which can form a coated surface having excellent solvent resistance and blocking resistance, and which can be easily disintegrated when recycled as used paper. It is an object of the present invention to provide a copolymer latex which can be formed with good handling properties and coating workability.

[0004]

The present invention is based on starches 5-20.
An ethylenically unsaturated monomer having a cyano group in the presence of 0 part by weight (hereinafter referred to as "cyano group-containing monomer").
10 to 60 parts by weight, a hydroxyl group-containing ethylenically unsaturated monomer (hereinafter referred to as "hydroxyl group-containing monomer") 10
60 parts by weight, (meth) acrylic acid alkyl ester monomer (hereinafter referred to as "acrylic ester monomer")
A copolymer obtained by emulsion polymerization of 10 to 80 parts by weight and 100 parts by weight of another ethylenically unsaturated monomer (hereinafter referred to as "other monomer") 0 to 20 parts by weight. The main point is polymer latex.

The present invention will be described in detail below. This will clarify the objects, configurations and effects of the present invention. The copolymer latex of the present invention, in the presence of starch,
A major feature is that it is obtained by emulsion polymerization of the specific monomer. In this case, if the starch is not added at the time of polymerization but is added after the polymerization, satisfactory solvent resistance cannot be achieved, and it is difficult to sufficiently reduce the viscosity of the latex, and it is difficult to improve the handleability and coating workability. It will be disadvantageous.

The starch used in the present invention is appropriately selected in consideration of the viscosity of the copolymer latex to be obtained, the desired characteristics of the coated surface and the like. The preferred starch is the molecular weight measured by high performance liquid chromatography. Is less than 100,000, and particularly preferred starch is 100 soluble in cold water.
It has a molecular weight of 0 to 10,000. Examples of such a relatively low molecular weight starch include enzyme-modified starch and oxidized starch. In this case, when the molecular weight of the starch is too high, the viscosity of the copolymer latex also becomes high, which is disadvantageous in terms of handleability and coating workability, and even when the molecular weight of the starch is too low, the solvent resistance of the coated surface is high. Property or blocking resistance may be insufficient.

The type of starch used in the present invention is not particularly limited, and suitable ones such as potato starch, sweet potato starch and corn starch can be selected and used.

Among the monomers used in the present invention, examples of the cyano group-containing monomer include (meth) acrylonitrile, α-chloroacrylonitrile, α-chloromethylacrylonitrile, α-methoxyacrylonitrile and α. -Vinyl cyanide compounds such as ethoxyacrylonitrile and vinylidene cyanide; 2-cyanoethyl (meth) acrylate, 2-cyanopropyl (meth) acrylate, 3-cyanopropyl (meth) acrylate, 2-cyanobutyl (meth) acrylate, 3 -Cyano group-containing esters of ethylenically unsaturated carboxylic acids such as cyanobutyl (meth) acrylate and 4-cyanobutyl (meth) acrylate;

Aromatic vinyl compounds containing a cyano group such as cyanostyrene, cyano-α-methylstyrene, cyanoethylstyrene, cyanoethyl-α-styrene; 2-cyano-1,3-butadiene, 2-cyano-1,3- Examples thereof include cyano group-containing aliphatic diene compounds such as pentadiene and 2-cyano-1,3-hexadiene.

Of these cyano group-containing monomers, acrylonitrile and methacrylonitrile are particularly preferable.
The cyano group-containing monomers may be used alone or in combination of two or more.

The amount of the cyano group-containing monomer used in the present invention is 10 to 60 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of all the monomers. If the amount of the cyano group-containing monomer used is less than 10 parts by weight or more than 60 parts by weight, sufficient solvent resistance of the coated surface cannot be obtained. The cyano group-containing monomer is particularly effective against aromatic solvents such as benzene, xylene and toluene.

The hydroxyl group-containing monomer in the present invention is an ethylenically unsaturated monomer having a hydroxyl group,
The N-alkylol group-containing crosslinking functional monomer described later is not included in the monomer.

Examples of such a hydroxyl group-containing monomer include hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2 -Hydroxybutyl (meth)
Acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate (the number of ethylene glycol units is, for example, 2 to 20), glycerol mono (meth) acrylate, butanetriol mono ( (Meth) acrylate, trimethylolalkane mono (meth) acrylate (the number of carbon atoms of the alkane is, for example, 1 to
Hydroxyl group-containing (meth) acrylates such as 3); (meth)
Examples thereof include ethylenically unsaturated alcohols such as allyl alcohol.

Of these hydroxyl group-containing monomers, 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate are particularly preferable. The hydroxyl group-containing monomer may be used alone or in combination of two or more.

The amount of the hydroxyl group-containing monomer used in the present invention is 10 to 60 parts by weight, preferably 15 to 40 parts by weight, based on 100 parts by weight of all the monomers. If the amount of the hydroxyl group-containing monomer used is less than 10 parts by weight or more than 60 parts by weight, sufficient solvent resistance of the coated surface cannot be obtained. The hydroxyl group-containing monomer is particularly effective for ester solvents such as ethyl acetate.

The acrylic ester monomer is an ester of (meth) acrylic acid and an unsubstituted alcohol. Here, "unsubstituted" means having no groups other than the alcoholic hydroxyl group and the hydrocarbon group.

Examples of acrylic ester monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n- (meth) acrylate. Butyl,
Isobutyl (meth) acrylate, t (meth) acrylic acid
-Butyl, n-pentyl (meth) acrylate, (meth)
Isopentyl acrylate, n-hexyl (meth) acrylate, isohexyl (meth) acrylate, n-heptyl (meth) acrylate, isoheptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth)
N-octyl acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, (meth) acrylic acid Examples thereof include esters of (meth) acrylic acid such as cyclohexyl and benzyl (meth) acrylate with an alcohol having 1 to 10 carbon atoms.

Of these acrylic ester monomers, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate and butyl methacrylate are particularly preferred. The acrylic ester monomers may be used alone or in admixture of two or more.

The amount of the acrylic ester monomer used in the present invention is 10 to 8 based on 100 parts by weight of all the monomers.
It is 0 parts by weight, but preferably 25 to 65 parts by weight. If the amount of the acrylic ester monomer used is less than 10 parts by weight or more than 80 parts by weight, sufficient solvent resistance of the coated surface cannot be obtained.

Further, other monomers include, for example, ethylenically unsaturated acid monomers, ethylenically unsaturated carboxylic acid amide monomers, aromatic vinyl monomers, and ethylenically unsaturated alcohol ester monomers. Monomers, ethylenically unsaturated ether monomers, monoethylenically unsaturated monomers such as vinyl halide monomers, and monomers that can introduce a crosslinked structure into the copolymer (hereinafter, "crosslinked One or more of the above (referred to as “monomer”) is used.

Among the above-mentioned other monomers, examples of the ethylenically unsaturated acid monomer include an ethylenically unsaturated carboxylic acid having a carboxyl group and / or an acid anhydride group, an ethylenically unsaturated sulfonic acid and the like. used. In the present invention, the use of the ethylenically unsaturated acid monomer can further improve the mechanical stability and chemical stability of the copolymer latex, the solvent resistance of the coated surface, and the like.

Examples of the ethylenically unsaturated carboxylic acid include (meth) acrylic acid, crotonic acid, cinnamic acid, (anhydrous) maleic acid, fumaric acid, (anhydrous) itaconic acid, citraconic acid and mesaconic acid. It is possible,
Acrylic acid and methacrylic acid are particularly preferred. Examples of the ethylenically unsaturated sulfonic acid include vinyl sulfonic acid, butadiene sulfonic acid, isoprene sulfonic acid and styrene sulfonic acid. These ethylenically unsaturated acid monomers can also be in the form of salts with, for example, ammonia, alkali metals and the like.

The preferred amount of the ethylenically unsaturated acid monomer used in the present invention is 100 parts by weight of all the monomers,
It is preferably 8 parts by weight or less, and particularly preferably 5 parts by weight or less. When the amount of the ethylenically unsaturated acid monomer used exceeds 8 parts by weight, the viscosity of the copolymer latex becomes high,
Handleability and coating workability tend to decrease.

Examples of the ethylenically unsaturated carboxylic acid amide monomer include (meth) acrylamide and N-
Methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) Acrylamide, Nn-propoxymethyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N-methoxymethyl (meth)
Examples thereof include acrylamide, N-methoxyethyl (meth) acrylamide, crotonic acid amide, cinnamic acid amide, maleic acid diamide, and fumaric acid diamide.

Examples of aromatic vinyl monomers include styrene, α-methylstyrene, methylstyrene,
Examples thereof include ethyl styrene, chlorostyrene, chloromethyl styrene, methoxy styrene, ethoxy styrene and acetoxy styrene.

Examples of the ester monomer of ethylenically unsaturated alcohol include vinyl formate, vinyl acetate,
Examples thereof include carboxylic acid esters such as vinyl propionate, vinyl butyrate and (meth) allyl acetate, and sulfonic acid esters such as vinyl alkyl sulfonate, (meth) allyl alkyl sulfonate and vinyl aryl sulfonate.

Examples of the ethylenically unsaturated ether monomer include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, methyl (meth) allyl ether, ethyl (meth) allyl ether and the like. You can

As the vinyl halide monomer, for example, vinyl chloride, vinylidene chloride, 1,2-dichloroethylene, vinyl bromide, vinylidene bromide, 1,2-
Dibromoethylene and the like can be mentioned.

Further, the crosslinkable monomer in the present invention is
A monomer capable of introducing a crosslinked structure into the copolymer simultaneously with and / or after the polymerization, and by using such a crosslinkable monomer, the solvent resistance and blocking resistance of the coated surface can be further improved. Can be improved.

As such a crosslinkable monomer, for example, a monomer having two or more ethylenically unsaturated groups (hereinafter,
It is called "polyvinyl-based monomer". ) Or an ethylenically unsaturated monomer having a crosslinkable functional group capable of reacting with other functional groups in the copolymer (hereinafter referred to as “crosslinkable functional monomer”).
Is used. Examples of the crosslinkable functional group in the crosslinkable functional monomer include an amino group, an epoxy group, an N-alkylol group and the like.

Examples of polyvinyl monomers include ethylene glycol, 1,2-propanediol, 1,3-
Propanediol, 1,3-butanediol, 1,4-
Butanediol, 1,5-pentanediol, 1,6-
Alkanediol di (meth) acrylates such as hexanediol;

Di (meth) acrylates of polyalkylene glycol (the number of alkylene glycol units is, for example, 2 to 20) such as polyethylene glycol and polypropylene glycol;

Other polyfunctional unsaturated esters such as vinyl (meth) acrylate, (meth) allyl (meth) acrylate, divinyl phthalate and di (meth) allyl phthalate;

Bis (meth) acrylamides such as N, N'-methylenebis (meth) acrylamide, N, N'-ethylenebis (meth) acrylamide, N, N'-hexamethylenebis (meth) acrylamide;

Polyvinyl aromatic compounds such as divinylbenzene, diisopropenylbenzene and trivinylbenzene;

Examples include polyfunctional unsaturated ethers such as divinyl ether and di (meth) allyl ether.

These polyvinyl monomers introduce a crosslinked structure into the copolymer simultaneously with polymerization. The amount of the polyvinyl-based monomer used in the present invention is preferably 5 parts by weight or less, particularly preferably 2 parts by weight or less, based on 100 parts by weight of all the monomers. When the amount of the polyvinyl-based monomer used is large (for example, 10 parts by weight or more), the disintegration property of the release paper tends to be reduced accordingly.

Next, among the crosslinking functional monomers, examples of the crosslinking functional monomer having an amino group include 2-aminoethyl (meth) acrylate, 2-dimethylaminoethyl (meth) acrylate, and the like. (Meth) acrylic acid 2-diethylaminoethyl, β-aminoethyl vinyl ether, β-
Dimethylaminoethyl vinyl ether, vinylamine,
(Meth) allylamine, aminostyrene, dimethylaminostyrene, vinylpyridine, N-vinylpyrrolidine,
Examples thereof include monomers containing a primary to tertiary amino group such as N-vinylpiperidine and N-vinylcarbazole.

The crosslinkable functional monomer having an amino group reacts with an acidic group contained in the copolymer at the same time as the polymerization and / or at the time of drying after the polymerization, so that an ionic bond, an amide bond, etc. To introduce a crosslinked structure.

Examples of the cross-linking functional monomer having an epoxy group include glycidyl (meth) acrylate,
Examples thereof include N-glycidyl (meth) acrylamide and (meth) allyl glycidyl ether.

These cross-linking functional monomers having an epoxy group can be used at the same time as the polymerization and / or at the time of drying after the polymerization,
For example, it reacts with a hydroxyl group, an acidic group or the like contained in the copolymer to form an ether bond, an ester bond or the like to introduce a crosslinked structure.

Examples of the crosslinkable functional monomer having an N-alkylol group include N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N, N-bis (hydroxymethyl) ( Examples thereof include N-hydroxyalkylated products of ethylenically unsaturated carboxylic acid amides such as (meth) acrylamide and N, N-bis (hydroxyethyl) (meth) acrylamide. The cross-linking functional monomer having these N-alkylol groups reacts with a hydroxyl group, an acidic group, etc. contained in the copolymer at the same time as the polymerization and / or at the time of drying after the polymerization to form an ether bond, An ester bond or the like is formed to introduce a crosslinked structure.

The amount of the crosslinking functional monomer used in the present invention is preferably 5 parts by weight or less, particularly preferably 2 parts by weight or less, based on 100 parts by weight of all the monomers. When the amount of the cross-linking functional monomer used is large (for example, 10 parts by weight or more), the disintegration property of the release paper tends to decrease accordingly.

In the present invention, the total amount of other monomers used is 0 to 20 parts by weight based on 100 parts by weight of all the monomers, but if it exceeds 20 parts by weight, solvent resistance, The balance of properties such as blocking resistance and disaggregation becomes insufficient.

In the present invention, the above-mentioned monomer is emulsion polymerized in the presence of starch, but in this case, the copolymer is calculated on the assumption that only the monomer is polymerized without using starch. The glass transition point (Tg) thereof is preferably -5 to + 45 ° C, more preferably 0 to + 35 ° C. Here, Tg can be calculated by the following formula. 1 / Tg = ΣW (i) / Tg (i) where Tg (i): Tg of homopolymer of i-th monomer, W (i): weight fraction of i-th monomer.

In this case, if the Tg of the copolymer is lower than -5 ° C, the blocking resistance of the coated surface tends to decrease,
If it exceeds + 45 ° C, the solvent resistance tends to decrease.

The amount of starch used in the present invention is 5 to 200 parts by weight, preferably 15 to 100 parts by weight, and particularly preferably 20 to 7 parts by weight, based on 100 parts by weight of all monomers.
0 parts by weight. In this case, even if the amount of starch used is less than 5 parts by weight or exceeds 200 parts by weight, it becomes difficult to impart sufficient solvent resistance to the coated surface.

Next, the method for emulsion-polymerizing the monomer in the presence of starch will be described in detail. That is, a general emulsion polymerization operation is carried out by adding starch, a monomer, a polymerization initiator, an emulsifier, etc. to water, and in the presence of various electrolytes, a pH adjusting agent, etc., if necessary.
It usually consists of polymerizing at a temperature of 50 to 90 ° C. with stirring. The polymerization time is usually about 5 to 15 hours.

As a method of adding each component in the emulsion polymerization, for example, (a) a method in which starch is dissolved in water and a monomer, a polymerization initiator, an emulsifier, etc. are added at once, dividedly or continuously, ( (B) A method in which starch and an emulsifier are dissolved in water, and a monomer, a polymerization initiator and the like are added thereto all at once, in divided or continuous manner, (c) An aqueous starch solution is separately prepared, and the aqueous solution and the monomer are added. An appropriate method such as a method of separately or continuously adding a polymerization initiator, an emulsifier and the like can be adopted. In this case, the monomer and the polymerization initiator may be mixed in advance or added separately, or the monomer may be emulsified in advance and added. The whole emulsion polymerization operation can be carried out in a batch system or a continuous system.

Examples of the polymerization initiator used in emulsion polymerization include potassium persulfate, ammonium persulfate, hydrogen peroxide, cumene hydroperoxide, isopropylbenzene hydroperoxide, paramenthane hydroperoxide, benzoyl peroxide and di-. Peroxides such as t-butyl peroxide and dilauroyl peroxide; 2,2′-azobisisobutyronitrile, 2,2 ′
-Asobisisovaleronitrile, 2,2'-azobisisocapronitrile, 2,2'-azobis (phenylisobutyronitrile), 2,2'-azobis (2-amidinopropane) dihydrochloride, etc. Azo compounds; ceric ammonium nitrate, redox type initiators and the like can be mentioned. As the reducing agent in the redox type initiator,
Examples thereof include sodium thiosulfate, sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, ferrous ammonium sulfate, glucose, sodium formaldehyde sulfoxylate, L-ascorbic acid and salts thereof. These polymerization initiators can be used alone or in admixture of two or more.

The amount of the polymerization initiator used is preferably 0.03 to 2% by weight, and more preferably 0.05 to 2% by weight, based on all the monomers.
1% by weight is preferred.

In emulsion polymerization, a chelating agent such as glycine, alanine and sodium ethylenediaminetetraacetate may be added to accelerate the polymerization.

In emulsion polymerization, if necessary,
Chain transfer agents can also be used. As the chain transfer agent, for example, α-methylstyrene dimer containing 60% by weight or more of 2,4-diphenyl-4-methyl-1-pentene component, terpinolene, terpinene, dipentene,
Examples thereof include n-dodecyl mercaptan, t-dodecyl mercaptan, dimethylxanthogen disulfide, diethylxanthogen disulfide, tetremethylthiuram monosulfide, tetraethylthiuram disulfide and dipentamethylthiuram disulfide.
Among these chain transfer agents, α-methylstyrene dimer, n-dodecyl mercaptan and t-dodecyl mercaptan are preferable. The chain transfer agents may be used alone or in admixture of two or more.

The amount of the chain transfer agent used is usually 15% by weight or less based on all the monomers.

As the emulsifier used in emulsion polymerization, various emulsifiers such as anionic surfactants, nonionic surfactants, cationic surfactants and amphoteric surfactants can be used. Agents and nonionic surfactants are preferred. As anionic surfactants, sulfuric acid ester salts of higher alcohols, polyoxyethylene
Alkyl ether sulfate, polyoxyethylene alkylphenyl ether sulfate, fatty oil sulfate, aliphatic amine or aliphatic amide sulfate, dibasic fatty acid ester sulfonate, aliphatic amide sulfone Acid salt, alkyl or alkenyl sulfonate, alkyl benzene sulfonate, alkyl sulfosuccinate, formalin condensed naphthalene sulfonate, phosphate ester salt of aliphatic alcohol, polyoxyethylene alkyl (phenyl) ether phosphate ester salt, etc. Can be mentioned.

Of these anionic surfactants, sulfate ester salts or sulfonate salts, specifically, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium diphenyl ether disulfonate, and sodium dialkyl ester sulfonate succinate are preferable.

As the nonionic surfactant, polyoxyethylene alkyl ester, polyoxyethylene alkylaryl ester, polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, glycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan. A fatty acid ester etc. can be mentioned. The surfactants may be used alone or in admixture of two or more.

In the emulsion polymerization, it is possible to use a reactive emulsifier having one or more ethylenically unsaturated bonds.

The amount of the emulsifier used in the emulsion polymerization is appropriately selected depending on the type of the emulsifier, the type and composition of the monomer, etc., but the preferable amount is 0.5 to 1 with respect to all the monomers.
It is 0% by weight.

The average particle size of the copolymer latex in the present invention is preferably 0.1 to 0.5 μm, more preferably 0.15 to 0.35 μm. The average particle size referred to here is a value obtained by treating the copolymer latex with uranyl acetate and osmic acid, taking an electron micrograph, and averaging the particle sizes of 100 or more copolymer particles.

The copolymer latex thus obtained is usually used after being appropriately neutralized with an alkaline substance such as potassium hydroxide, sodium hydroxide or ammonium hydroxide.

Further, the copolymer latex of the present invention comprises
If necessary, within the range that does not impair the characteristics, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, dextran,
Water-soluble polymer compounds such as casein, gelatin, guar gum and its derivatives, xanthan gum, poly (meth) acrylic acid and its salts, polyvinyl alcohol, polyethylene oxide and alginates; (meth) acrylic resin emulsion, vinyl acetate resin emulsion , Vinyl chloride resin emulsion, vinylidene chloride resin emulsion, fluororesin emulsion, styrene resin emulsion, urethane resin emulsion, rubber emulsion, and other polymer emulsions, defoaming agents, leveling agents,
Additives such as a film forming auxiliary agent, an antiseptic agent, an antifungal agent, an antiaging agent, an ultraviolet absorber, a dye / pigment, and an antifreezing agent may be further added.

The copolymer latex of the present invention is useful for forming a solvent-resistant coated surface on paper or a substrate similar thereto, particularly for forming an undercoat as a solvent-resistant barrier layer in release paper. That is, most of the release agents are solvent-type ones in which an addition reaction type silicone resin is dissolved in an organic solvent such as toluene or ethyl acetate. Such a release agent is generally expensive, and a barrier layer that does not permeate these solvents and is not attacked by these solvents is necessary in order to exert a sufficient effect with a small amount of coating. The copolymer latex of is very suitable as the barrier layer.

Further, the copolymer latex of the present invention can be widely used for forming a solvent resistant coated surface on various substrates other than a paper substrate. Examples of such other base materials include cement-based materials such as concrete, mortar, and slate; polystyrene, styrene-acrylonitrile resin, high-impact polystyrene, ABS resin, (meth) acrylic resin, vinyl chloride-based resin, chloride. Vinylidene resin, polyester, polycarbonate, polyamide, polyurethane, melamine resin, phenol resin, urea resin, epoxy resin and other synthetic resins, semi-synthetic resins and natural resins; iron, steel, stainless steel, zinc, tinplate, copper, aluminum, In addition to metals such as lead, wood, plywood, vulcanized rubber, glass, roof tile, plaster, ceramics and the like can be mentioned.

When coating the copolymer latex of the present invention, various coating devices such as an air knife coater, roll coater, calendar coater, gravure coater, bar coater, blade coater and size press coater are used. be able to. The coating operation can be carried out batchwise or continuously.

The coating amount of the copolymer latex of the present invention on a substrate is appropriately adjusted depending on the properties of the substrate, the intended use of the coated article, etc. In the case of an undercoat for release paper, for example,
Usually, it is about 5 to 10 g / cm ² .

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples unless it exceeds the gist.

【Example】

Examples 1 to 8 and Comparative Examples 1 to 6 Production of Copolymer Latex A In a reaction vessel equipped with a stirrer and a heating device, 120 parts by weight of water and 40 parts by weight of enzyme-modified starch soluble in cold water were loaded to complete the reaction. After melting and purging with nitrogen, the mixture was heated to 60 ° C.
In another container, 40 parts by weight of water, 2.5 parts by weight of sodium dodecylbenzenesulfonate, 50 parts by weight of acrylonitrile, 25 parts by weight of 2-hydroxyethyl methacrylate,
An emulsion was prepared by mixing 23 parts by weight of n-butyl acrylate and 2 parts by weight of acrylic acid, and the emulsion was continuously added to the reaction vessel over 6 hours while stirring. Simultaneously with the start of the addition of the emulsion, 1 part by weight of potassium persulfate was added to start the polymerization, and the reaction temperature was adjusted to 6
Polymerization was continued while maintaining the temperature at 0 ° C, and after the addition of the emulsion was completed, the reaction temperature was raised to 80 ° C and maintained for 3 hours to complete the polymerization. After polymerization, the mixture was cooled and 10% by weight of sodium hydroxide was added to adjust the pH of the copolymer latex to 7
Adjusted to.

Production of Copolymer Latex B After the inside of a reaction vessel equipped with a stirrer and a heating device was replaced with nitrogen, 160 parts by weight of water and 50 parts by weight of enzyme-modified starch soluble in cold water were charged and completely dissolved to give dodecyl. Sodium benzenesulfonate 3.0 parts by weight, acrylonitrile 30
Parts by weight, 10 parts by weight of 2-hydroxyethyl acrylate, 30 parts by weight of 2-hydroxyethyl methacrylate,
49 parts by weight of n-butyl acrylate and 2 parts by weight of methacrylic acid were added and heated to 60 ° C. with stirring. Then
Polymerization was started by adding 1 part by weight of potassium persulfate, the reaction temperature was kept at 60 ° C. for 6 hours, and then the reaction temperature was raised to 70 ° C. for another 2 hours to complete the polymerization. It was After the polymerization, the mixture was cooled and 10 wt% sodium hydroxide was added to adjust the pH of the copolymer latex to 7.

Copolymer Latex C to H and Copolymer
Production of Latex J to M Using the monomer mixture and the enzyme-modified starch shown in Table 1 or Table 2, polymerization was carried out in the same manner as in the production of copolymer latex A to produce each copolymer latex.

[0070] In addition to not using the copolymer latex I of manufacturing starch, by polymerization in the same manner as in the production of copolymer latex A, were prepared copolymer latex I.

Preparation of copolymer latex N Polymerization was carried out in the same manner as in the preparation of copolymer latex E except that starch was not used, and then 60 parts by weight of cold water-soluble enzyme-modified starch was blended as an aqueous solution to prepare a copolymer. Latex N was produced.

Coating and Evaluation of Copolymer Latex A to N
Valence Each copolymer latex was diluted with water, the viscosity 60-8
Adjusted to 0 cps. In this case, the copolymer latex A to
In M, the solid content was 40% by weight or more, but in the copolymer latex N, the solid content was about 35% by weight. These copolymer latexes were applied to high-quality paper with a basis weight of 40 g / m ² .
After coating with a bar coater to a dry coating amount of 5 g / m ² and drying at 150 ° C. for 1 minute, the following test was conducted. The evaluation results are shown in Table 1 (Examples 1 to 8) and Table 2.
(Comparative Examples 1 to 6).

Solvent resistance test: One drop each of toluene or ethyl acetate was dropped on the coated surface and it was observed whether or not it permeated.
Further, the place where toluene or ethyl acetate was dropped was lightly rubbed to observe whether or not the coated surface was corroded or clouded. The evaluation was performed according to the following criteria. ⊚: The coated surface does not penetrate toluene and ethyl acetate, is not attacked, and does not cloud. ◯: The coated surface does not permeate toluene and ethyl acetate, but clouding occurs after the droplets are wiped off. Δ: It is clear that the coated surface was slightly permeated with toluene or ethyl acetate, the droplets were wiped off, and then the solvent was attacked. X: It is clear that the coated surface is permeated with toluene or ethyl acetate or is attacked by droplets.

Blocking resistance test: The tackiness of the coated surface was evaluated by finger touch judgment. The evaluation was performed according to the following criteria. ⊚: Does not stick at all. ○: Adhesion slightly. Δ: There is tackiness. X: Sticky and sticky.

Disintegration test: The coated paper was cut into small pieces, loaded into a disintegrator with a large amount of water and stirred, and the disintegration time and disintegration state of the paper were observed. The evaluation was performed according to the following criteria. ⊚: Disaggregated within 2 minutes to form a single fiber. ◯: Disaggregated within 5 minutes to form a single fiber. Δ: After defibration for about 15 minutes, a part that is not defibrated remains. X: Disaggregation is extremely difficult.

[0076]

[Table 1]

[0077]

[Table 2]

As is clear from Tables 1 and 2, the coated surface of the copolymer latex of the present invention is excellent in solvent resistance and blocking resistance, and the coated paper is also excellent in disintegration property. On the other hand, when starch is not used at all (Comparative Example 1), both solvent resistance and disaggregation are insufficient, and the monomer composition is out of the range of the present invention (Comparative Example 2).
4), if the amount of starch used is too large (Comparative Example 5), the solvent resistance becomes insufficient, and if the starch is compounded after polymerization (Comparative Example 6), the solvent resistance becomes insufficient. As well,
The solid content is about 35 when the viscosity is adjusted to 60-80 cps.
It was as low as 10% by weight, and the rate of penetrating the paper during coating was high, making it difficult to form a desired coated surface.

[0079]

INDUSTRIAL APPLICABILITY The copolymer latex of the present invention has a solvent resistance comparable to that of polyethylene and can form a coated surface excellent in blocking resistance, and is easily disintegrated when recycled as waste paper. It is possible to form an undercoat for various release papers, and also has high adhesion to various base materials including paper base materials and release agents. It also has low viscosity even at relatively high solids, and easy handling and coating workability. Is good.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taiji Tsurusako 2-11-24 Tsukiji, Chuo-ku, Tokyo Inside Nippon Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] 1. In the presence of 5 to 200 parts by weight of starch, 10 to 60 parts by weight of an ethylenically unsaturated monomer having a cyano group, and 10 to 6 parts of an ethylenically unsaturated monomer having a hydroxyl group.
It is obtained by emulsion polymerization of 0 part by weight, 10 to 80 parts by weight of a (meth) acrylic acid alkyl ester monomer, and 100 parts by weight of a monomer consisting of 0 to 20 parts by weight of another ethylenically unsaturated monomer. Copolymer latex.