JP3287088B2 - Copolymer latex - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, paper has been used in large quantities in a wide range of fields, whether for consumer or industrial use, but today, paper or a substrate similar to paper is not used as it is, It is often used practically as so-called processed paper or the like that has been subjected to processing. And such a processed paper often needs a barrier layer having a property of preventing various solvents from penetrating or being not attacked by the solvent, that is, a “solvent resistance”. For example, when manufacturing release paper, the release agent used is often a solvent type, and the coating material used to form the barrier layer is:
In order to achieve the desired effect with a small coating amount, it is necessary to have sufficient solvent resistance. Therefore, in the production of release paper, a method of laminating polyethylene as an undercoat on a paper base material and coating a release agent thereon is dominant. However, although the undercoat made of polyethylene certainly has good solvent resistance as a barrier layer, it is difficult to disintegrate such processed paper, so that it can be reused from the viewpoint of environmental protection and resource utilization. In addition, there is a problem in that separate collection is required for recycling, which raises the processing cost. On the other hand, in order to solve the problem of such an undercoat made of polyethylene, a method using starch or a derivative thereof as a coating material (for example, Japanese Patent Application Laid-Open No.
Use of a water-soluble copolymer, for example, a copolymer containing a hydrophilic monomer such as an ethylenically unsaturated carboxylic acid or a hydroxyalkyl ester thereof and an alkyl (meth) acrylate as main components. (For example, Japanese Patent Laid-Open No. 1-156598, Japanese Patent Publication No. 5-517)
No. 20) is proposed. However, in these methods, it cannot be said that the solvent resistance as the barrier layer is sufficient, and also that the glass transition point of the water-soluble copolymer is low, so that it has tackiness and is likely to cause blocking. There are drawbacks.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an undercoat for release paper which can form a coated surface having excellent solvent resistance and blocking resistance and can be easily disaggregated when recycled as used paper. It is an object of the present invention to provide a copolymer latex which can form a polymer latex and has good handleability and coating workability.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a method for preparing a starch
In the presence of 0 parts by weight, an ethylenically unsaturated monomer having a cyano group (hereinafter, referred to as “cyano group-containing monomer”).
10 to 60 parts by weight of an ethylenically unsaturated monomer having a hydroxyl group (hereinafter, referred to as "hydroxyl group-containing monomer")
60 parts by weight of a (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 a monomer comprising 0 to 20 parts by weight of another ethylenically unsaturated monomer (hereinafter referred to as "other monomer"). The gist of the present invention is a polymer latex.

Hereinafter, the present invention will be described in detail. This will clarify the objects, configurations and effects of the present invention. The copolymer latex of the present invention, in the presence of starch,
There is a great feature in that the specific monomer is obtained by emulsion polymerization. In this case, if the starch is not added during the polymerization but is added after the polymerization, satisfactory solvent resistance is not achieved, and it is difficult to sufficiently lower the viscosity of the latex, and the handling and coating workability are difficult. Disadvantage in terms of performance.

[0006] The starch used in the present invention is appropriately selected in consideration of the viscosity of the obtained copolymer latex, desired properties of the coated surface, and the like. Preferred starches have a molecular weight measured by high performance liquid chromatography. Is 100,000 or less, and particularly preferred starch is 100% soluble in cold water.
It has a molecular weight of 0 to 10,000. Examples of such relatively low molecular weight starch include enzyme-modified starch and oxidized starch. In this case, if 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. Properties and blocking resistance may be insufficient.

[0007] The type of starch used in the present invention is not particularly limited. For example, potato starch, sweet potato starch, corn starch and the like can be selected and used.

Next, among the monomers used in the present invention, examples of cyano group-containing monomers include (meth) acrylonitrile, α-chloroacrylonitrile, α-chloromethylacrylonitrile, α-methoxyacrylonitrile, 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, and 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.

Among these cyano group-containing monomers, acrylonitrile and methacrylonitrile are particularly preferred.
The cyano group-containing monomers can 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 monomers. If the amount of the cyano group-containing monomer 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-containing monomer in the present invention is an ethylenically unsaturated monomer having a hydroxyl group.
The monomer does not include an N-alkylol group-containing crosslinkable functional monomer described below.

Examples of such a hydroxyl group-containing monomer include hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, -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 (alkane has 1 to
3) hydroxyl group-containing (meth) acrylates; (meth)
Examples include ethylenically unsaturated alcohols such as allyl alcohol.

Among these hydroxyl group-containing monomers, 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate are particularly preferred. The hydroxyl group-containing monomers can 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 monomers. If the amount of the hydroxyl group-containing monomer is less than 10 parts by weight or more than 60 parts by weight, sufficient solvent resistance of the coated surface cannot be obtained. Hydroxyl group-containing monomers are particularly effective against 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 group other than the alcoholic hydroxyl group and the hydrocarbon group.

The acrylic ester monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n- (meth) acrylate. Butyl,
Isobutyl (meth) acrylate, t (meth) acrylate
-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 Esters of (meth) acrylic acid, such as cyclohexyl and benzyl (meth) acrylate, and an alcohol having 1 to 10 carbon atoms can be exemplified.

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 combination 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 monomers.
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 esters of ethylenically unsaturated alcohols. Monomer, an ethylenically unsaturated ether monomer, a monoethylenically unsaturated monomer such as a vinyl halide monomer, or a monomer capable of introducing a crosslinked structure into a copolymer (hereinafter referred to as “crosslinked Or more).

Among the 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, and an ethylenically unsaturated sulfonic acid. used. In the present invention, by using the ethylenically unsaturated acid monomer, the mechanical stability and chemical stability of the copolymer latex, the solvent resistance of the coated surface, and the like can be further improved.

Examples of the ethylenically unsaturated carboxylic acid include (meth) acrylic acid, crotonic acid, cinnamic acid, maleic acid (anhydrous), fumaric acid, itaconic acid (anhydride), citraconic acid, mesaconic acid and the like. It is possible,
Particularly, acrylic acid and methacrylic acid are 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 monomers.
It is preferably at most 8 parts by weight, particularly preferably at most 5 parts by weight. When the amount of the ethylenically unsaturated acid monomer exceeds 8 parts by weight, the viscosity of the copolymer latex increases,
There is a tendency that handleability and coating workability are reduced.

The ethylenically unsaturated carboxylic acid amide monomer includes, for example, (meth) acrylamide, 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)
Acrylamide, N-methoxyethyl (meth) acrylamide, crotonic amide, cinnamamide, maleic diamide, fumaric diamide and the like can be mentioned.

The aromatic vinyl monomers include, for example, styrene, α-methylstyrene, methylstyrene,
Examples thereof include ethylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, ethoxystyrene, and acetoxystyrene.

The ester monomers of the ethylenically unsaturated alcohol include, for example, 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, for example, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, methyl (meth) allyl ether, and ethyl (meth) allyl ether. Can be.

The vinyl halide monomers include, 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 comprises
A monomer capable of introducing a crosslinked structure into the copolymer at the same time as and / or after the polymerization, and by using such a crosslinkable monomer, the solvent resistance and the 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, referred to as a monomer having two or more ethylenically unsaturated groups)
It is called "polyvinyl 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, and an N-alkylol group.

Examples of the polyvinyl monomer include ethylene glycol, 1,2-propanediol, 1,3-
Propanediol, 1,3-butanediol, 1,4-
Butanediol, 1,5-pentanediol, 1,6-
Di (meth) acrylates of alkanediols such as hexanediol;

Di (meth) acrylates of polyalkylene glycols (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, 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 the polymerization. The amount of the polyvinyl monomer to be 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 monomers. When the amount of the polyvinyl-based monomer used is large (for example, 10 parts by weight or more), the disintegration of a release paper tends to decrease 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, 2-Diethylaminoethyl (meth) acrylate, β-aminoethyl vinyl ether, β-
Dimethylaminoethyl vinyl ether, vinylamine,
(Meth) allylamine, aminostyrene, dimethylaminostyrene, vinylpyridine, N-vinylpyrrolidine,
Monomers containing primary to tertiary amino groups such as N-vinylpiperidine and N-vinylcarbazole can be mentioned.

The cross-linking functional monomer having an amino group reacts with an acidic group contained in the copolymer, for example, at the same time as polymerization and / or during drying after polymerization to form an ionic bond, an amide bond, or the like. To form a crosslinked structure.

Examples of the crosslinkable functional monomer having an epoxy group include glycidyl (meth) acrylate,
N-glycidyl (meth) acrylamide, (meth) allyl glycidyl ether and the like can be mentioned.

These cross-linkable functional monomers having an epoxy group can be prepared at the same time as the polymerization and / or upon 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, thereby introducing 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 ethylenically unsaturated carboxylic acid amides such as (meth) acrylamide and N, N-bis (hydroxyethyl) (meth) acrylamide. The crosslinked functional monomer having these N-alkylol groups reacts with a hydroxyl group, an acidic group, or the like contained in the copolymer at the same time as polymerization and / or during drying after polymerization to form an ether bond, An ester bond or the like is formed to introduce a crosslinked structure.

The amount of the crosslinkable 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 monomers. When the amount of the cross-linking functional monomer used is large (for example, 10 parts by weight or more), the disintegration of a release paper tends to decrease accordingly.

In the present invention, the total amount of other monomers used is from 0 to 20 parts by weight based on 100 parts by weight of all the monomers. 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. In this case, the calculation of the copolymer assumes that only the monomer is polymerized without using starch. Has a glass transition point (Tg) of preferably −5 to + 45 ° C., and more preferably 0 to + 35 ° C. Here, Tg can be calculated by the following equation. 1 / Tg = ΣW (i) / Tg (i) where Tg (i) is the Tg of the homopolymer of the i-th monomer, and W (i) is the weight fraction of the i-th monomer.

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

Next, a method of emulsion-polymerizing a monomer in the presence of starch will be described in detail. That is, a general emulsion polymerization operation is to add starch, a monomer, a polymerization initiator, an emulsifier, and the like to water, and optionally, in the presence of various electrolytes, a pH adjuster, and the like.
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.

Examples of the method of adding each component in the emulsion polymerization include (a) dissolving starch in water, and adding a monomer, a polymerization initiator, an emulsifier, and the like, collectively, dividedly or continuously; B) a method in which a starch and an emulsifier are dissolved in water, and a monomer, a polymerization initiator and the like are added thereto at once, dividedly or continuously, (c) an aqueous starch solution is separately prepared, An appropriate method such as a method in which a polymerization initiator, an emulsifier, and the like are separately, separately or continuously added can be employed. 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 by a batch system or a continuous system.

Examples of the polymerization initiator used in the emulsion polymerization include potassium persulfate, ammonium persulfate, hydrogen peroxide, cumene hydroperoxide, isopropylbenzene hydroperoxide, paramenthane hydroperoxide, benzoyl peroxide, and di-peroxide. 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 initiators and the like can be mentioned. As the reducing agent in the redox-based initiator,
Examples thereof include sodium thiosulfate, sodium sulfite, sodium bisulfite, ferrous sulfate, ammonium ferrous sulfate, glucose, sodium formaldehyde sulfoxylate, L-ascorbic acid and salts thereof. These polymerization initiators can be used alone or in combination of two or more.

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

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

In the emulsion polymerization, if necessary,
Chain transfer agents can also be used. Examples of the chain transfer agent include α-methylstyrene dimer containing at least 60% by weight of 2,4-diphenyl-4-methyl-1-pentene component, terpinolene, terpinene, dipentene,
Examples thereof include n-dodecyl mercaptan, t-dodecyl mercaptan, dimethyl xanthogen disulfide, diethyl xanthogen disulfide, tetramethylthiuram monosulfide, tetraethylthiuram disulfide, dipentamethylthiuram disulfide and the like.
Among these chain transfer agents, α-methylstyrene dimer, n-dodecyl mercaptan and t-dodecyl mercaptan are preferred. The chain transfer agents can be used alone or in combination of two or more.

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

As the emulsifier used in the emulsion polymerization, various emulsifiers such as anionic surfactants, nonionic surfactants, cationic surfactants and amphoteric surfactants can be used. Agents and nonionic surfactants are preferred. Examples of anionic surfactants include sulfates 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 of aliphatic alcohol, polyoxyethylene alkyl (phenyl) ether phosphate, etc. Can be mentioned.

Of these anionic surfactants, sulfate salts or sulfonates, specifically, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium diphenylether disulfonate, and sodium dialkyl succinate sulfonate are preferred.

Examples of the nonionic surfactant include polyoxyethylene alkyl ester, polyoxyethylene alkyl aryl ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, glycerin fatty acid ester, sorbitan fatty acid ester, and polyoxyethylene sorbitan. Fatty acid esters and the like can be mentioned. The surfactants may be used alone or in combination of two or more.

In the emulsion polymerization, a reactive emulsifier having one or more ethylenically unsaturated bonds may be used.

The amount of the emulsifier used in the emulsion polymerization is appropriately selected depending on the kind of the emulsifier, the kind and the composition of the monomer, and the preferred amount is from 0.5 to 1 based on all the monomers.
0% by weight.

The average particle diameter of the copolymer latex in the present invention is preferably from 0.1 to 0.5 μm, more preferably from 0.15 to 0.35 μm. Here, the average particle diameter is a value obtained by treating a copolymer latex with uranyl acetate and osmic acid, taking an electron micrograph thereof, and number-averaging the particle diameters 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 includes:
If necessary, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, dextran, as long as the properties are not impaired.
Casein, gelatin, guar gum and its derivatives, xanthan gum, poly (meth) acrylic acid and its salts, polyvinyl alcohol, polyethylene oxide, water-soluble polymer compounds such as alginate; (meth) acrylic resin emulsion, vinyl acetate resin emulsion Other polymer emulsions such as vinyl chloride resin emulsion, vinylidene chloride resin emulsion, fluorine resin emulsion, styrene resin emulsion, urethane resin emulsion, rubber emulsion, defoamer, leveling agent,
Additives such as a film forming aid, a preservative, a fungicide, an antioxidant, an ultraviolet absorber, a dye and a pigment, and an antifreezing agent can be further added.

The copolymer latex of the present invention is useful for the formation of an undercoat as a solvent-resistant barrier layer on paper or similar substrates, especially on release paper. That is, many of the release agents are of a solvent type obtained by dissolving an addition reaction type silicone resin in an organic solvent such as toluene or ethyl acetate. Such release agents are generally expensive, and in order to exhibit a sufficient effect with a small amount of coating, a barrier layer that does not penetrate these solvents and is not affected by these solvents is required. Is particularly suitable as this 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, impact-resistant polystyrene, ABS resin, (meth) acrylic resin, vinyl chloride-based resin, chloride Synthetic resin such as vinylidene resin, polyester, polycarbonate, polyamide, polyurethane, melamine resin, phenol resin, urea resin, epoxy resin, semi-synthetic resin and natural resin; iron, steel, stainless steel, zinc, tin, copper, aluminum, In addition to metals such as lead, wood, plywood, vulcanized rubber, glass, tile, plaster, ceramics, and the like can be given.

When coating the copolymer latex of the present invention, various coating apparatuses such as an air knife coater, a roll coater, a calendar coater, a gravure coater, a bar coater, a blade coater, and a size press coater are used. be able to. The coating operation can be performed in a batch system or a continuous system.

The coating amount of the copolymer latex of the present invention on a substrate is appropriately adjusted according to the properties of the substrate, the use of the coated product, and the like.
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 embodiments at all 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 cold water-soluble enzyme-modified starch were loaded and completely mixed. After dissolving 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 initiate polymerization, and the reaction temperature was lowered to 6
The polymerization was continued at 0 ° C., and after the addition of the emulsion was completed, the reaction temperature was raised to 80 ° C., and further maintained for 3 hours to complete the polymerization. After the polymerization, the mixture was cooled and 10% by weight of sodium hydroxide was added to adjust the pH of the copolymer latex to 7
Was adjusted.

Preparation 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 cold-water-soluble enzyme-modified starch were loaded and completely dissolved. 3.0 parts by weight of sodium benzenesulfonate, 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, polymerization was performed for 6 hours while maintaining the reaction temperature at 60 ° C., and then the reaction temperature was raised to 70 ° C., and polymerization was further performed for 2 hours to complete the polymerization. Was. After the polymerization, the mixture was cooled, and the pH of the copolymer latex was adjusted to 7 by adding 10% by weight of sodium hydroxide.

Copolymer latex C to H and copolymer
Production of Latexes 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 the copolymer latex A to produce each copolymer latex.

Preparation of Copolymer Latex I Polymerization was performed in the same manner as in the preparation of Copolymer Latex A, except that starch was not used, to prepare 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. Then, 60 parts by weight of cold-water-soluble enzyme-modified starch was blended as an aqueous solution, and the copolymer was prepared. Latex N was produced.

Coating and Evaluation of Copolymer Latexes 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 ~
In the case of M, the solid content was 40% by weight or more, but in the case of the copolymer latex N, the solid content was about 35% by weight. These copolymer latexes are converted into high-quality paper having a basis weight of 40 g / m ² ,
Using a bar coater, the composition was coated so as to have a dry coating amount of 5 g / m ² , dried at 150 ° C. for 1 minute, and then subjected to the following test. The evaluation results are shown in Table 1 (Examples 1 to 8) and Table 2.
The results are shown in (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 portion where the toluene or ethyl acetate was dropped was lightly rubbed to observe whether the coated surface was damaged or fogged. The evaluation was performed according to the following criteria. ◎: The coated surface does not permeate and does not permeate toluene and ethyl acetate, and no fogging occurs. ：: The coated surface does not penetrate toluene and ethyl acetate, but fogging occurs after wiping the droplets. Δ: It is clear that the coated surface slightly penetrated toluene and ethyl acetate, wiped off the droplets, and was then attacked by the solvent. D: It is clear that the coated surface is impregnated with toluene or ethyl acetate or damaged by droplets.

Blocking resistance test: The adhesiveness of the coated surface was evaluated by finger touch judgment. The evaluation was performed according to the following criteria. A: No adhesion at all. ：: Slightly adhered. Δ: Adhesive. X: Stickiness is strong and sticky.

Disintegration test: The coated paper was cut into small pieces, loaded into a disintegrator together with a large amount of water, and stirred to observe the disintegration time and disintegration state of the paper. The evaluation was performed according to the following criteria. ：: Disintegrated within 2 minutes to form a single fiber. ：: Disintegrated within 5 minutes to form a single fiber. Δ: A part that does not clearly disintegrate remains even after disintegration for about 15 minutes. ×: Disintegration 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 has excellent solvent resistance and blocking resistance, and the coated paper has excellent disintegration properties. On the other hand, when no starch was used (Comparative Example 1), both the solvent resistance and the disaggregation were insufficient, and the monomer composition was out of the range of the present invention (Comparative Example 2).
4), even if the amount of starch used is too large (Comparative Example 5), the solvent resistance becomes insufficient, and when the starch is blended after polymerization (Comparative Example 6), the solvent resistance is insufficient. As well,
When the viscosity is adjusted to 60-80 cps, the solid content is about 35
% By weight, and the rate of penetration into the paper during coating increased, making it difficult to form a desired coated surface.

[0079]

EFFECT OF THE INVENTION The copolymer latex of the present invention has a solvent resistance comparable to that of polyethylene and can form a coated surface having excellent blocking resistance, and can be easily disintegrated when recycled as used paper. It can form an undercoat for release paper, and has high adhesiveness to various substrates including paper-based substrates and release agents. It has low viscosity even at relatively high solids, and is easy to handle and apply. Is good.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Taiji Tsurusako 2--11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (56) References JP-A-57-153014 (JP, A) JP-A-63-203895 (JP, A) JP-A-58-87105 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 251/00-251/02

Claims (1)

(57) [Claims] 1. An ethylene unsaturated monomer having a cyano group in an amount of 10 to 60 parts by weight and an ethylenically unsaturated monomer having a hydroxyl group in an amount of 10 to 6 parts by weight in the presence of 5 to 200 parts by weight of starch.
0 parts by weight, 100 parts by weight of a monomer comprising 10 to 80 parts by weight of an alkyl (meth) acrylate monomer and 0 to 20 parts by weight of another ethylenically unsaturated monomer are obtained by emulsion polymerization. Copolymer latex.