JP2000234044A - Activation energy ray-curable aqueous emulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an emulsion which can give a cured film free from coloration and odor and excellent in solvent resistance and water resistance by dispersing a polymer comprising units derived from a (meth)acrylate monomer having a specified structure and a compound having at least two (meth)acryloyl groups in an aqueous medium. SOLUTION: This emulsion is prepared by dispersing (A) a polymer comprising units derived from a compound having an ethylenic unsaturation and a cyclic imido group represented by the formula and (B) a compound having at least two (meth)acryloyl groups in an aqueous medium, and wherein 20-99.9 pts.wt. component A and 80-0.1 pt.wt. component B are present per 100 pts.wt. total of components A and B. The emulsion is excellent in the ability to be cured with an activation energy ray. In the formula, R1 and R2, which are independent of each other, are 4C or lower alkyl groups, or one of them is hydrogen, and the other is a 4C or lower alkyl, or may be combined with each other to form a carbocyclic ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous emulsion which can be cured by irradiation with an active energy ray such as an electron beam or an ultraviolet ray. The emulsion of the present invention is used for coating materials such as paints, coating agents and printing inks. ,
It is useful as a bonding agent, adhesive, filler, molding material, resist and the like for non-woven fabrics, and is also useful as a coating material among them, especially overprint varnish (hereinafter referred to as OP).
V) and wood coatings, which can be awarded in these technical fields.

[0002]

2. Description of the Related Art In recent years, the emission of organic solvents and cleaning agents used in various industries and the like into the atmosphere has increased the air pollution on a global scale, and there is a concern about the effects on living organisms. . For this reason, attempts have been made to change the composition used for applications such as paints, inks and adhesives from a conventionally used solvent type to an aqueous type.

[0003] In addition, in the above-mentioned applications, a study has been made to make a reactive polymer curable by an active energy ray used as a base polymer into an aqueous solution. For example, a method for producing a polymer having a carboxyl group in water in the presence of a surfactant, and subjecting the obtained polymer to an addition reaction of a compound having an epoxy group and an unsaturated group to produce an unsaturated group-containing polymer And the like (Japanese Patent Laid-Open No. 6-21 / 1994)
1950).

On the other hand, as a method for removing an organic solvent in an OPV application, a method using an ultraviolet curable composition containing no organic solvent has been studied. As such an ultraviolet-curable OPV composition, a composition comprising an oligoester (meth) acrylate such as polyester acrylate, epoxy acrylate and urethane acrylate and a reactive diluent is known. For example, JP-A-3-
JP-A-292371 discloses a composition comprising an acrylate having a specific structure and a thermoplastic polymer having a specific softening point. As another method, an aqueous composition in which a polymer is suspended or emulsified in water is known (Japanese Patent Application Laid-Open No. SHO 51-51).
Nos. 17922 and 51-23531 and JP-A-6-212950.

[0005] As a method for converting the organic solvent into a non-organic solvent in the application of paints, a method using an ultraviolet curable composition containing no organic solvent has been studied as described above. As the UV-curable coating composition, polyester acrylate,
Those comprising oligoester (meth) acrylates such as epoxy acrylate and urethane acrylate and a reactive diluent are known. For example, Japanese Patent Application Laid-Open No. 5-924
No. 7 discloses an ultraviolet curable composition containing a urethane acrylate having a specific structure and an unsaturated polyester. As another method, use of an aqueous composition composed of a polymer emulsion is also being studied as described above (JP-A-51-17922, JP-A-51-23531, and JP-A-5-23531). No. 211950).

[0006]

When the emulsion of the unsaturated group-containing polymer obtained by the above-mentioned production method is used for various purposes, the polymer is hardened by irradiating ultraviolet rays. It is necessary to mix a photopolymerization initiator. However, the aqueous emulsion comprising the unsaturated group-containing polymer and the photopolymerization initiator has a problem of odor and coloring of the cured film because a decomposition product of the photopolymerization initiator remains in the cured film. there were. or,
In many cases, the emulsion had insufficient hardness of the cured film.

On the other hand, a conventional solvent-free ultraviolet-curable OPV
The composition had insufficient adhesion of the cured film to paper, printing ink, or the like as a base material. The cause of such low adhesion is compared with a composition containing a solvent-dried polymer or a composition containing a thermosetting polymer, which cures while gradually relaxing strain by thermal drying or thermal curing. In addition, since the curing time of the ultraviolet-curable composition is short, stress strain caused by volume shrinkage during curing is easily accumulated in the cured film. In order to improve the adhesion of the ultraviolet-curable composition, a method of mixing and dissolving a non-reactive resin such as an acrylic polymer, a polyester, and a petroleum resin in the composition to lower the volume shrinkage during curing has also been attempted. However, there is a problem that the curability of the composition and the solvent resistance of the cured product are reduced. Furthermore, since such solvent-free compositions are generally high in viscosity, workability at the time of production of the composition and at the time of application of the composition is often poor. In addition, the conventional water-based OPV composition, the dried coating film is solvent-resistant, water-resistant,
The surface gloss and the adhesion to the substrate were insufficient, and water resistance was particularly liable to be insufficient.

Also, in the conventional solvent-free UV-curable coating composition, the curing time of the composition is short for the same reason as in the case of the OPV composition, so that the cured film has poor adhesion to the substrate. There was a problem that it was insufficient.
Also, as described above, such a solventless composition generally has a high viscosity, so that the workability at the time of manufacturing the composition and at the time of coating the composition is poor. In the case of the conventional water-based coating composition, the dried coating film is insufficient in hardness, solvent resistance and water resistance, and also has insufficient surface gloss and adhesion to a substrate, particularly Water resistance was apt to be insufficient.

The present inventors have proposed an aqueous emulsion which is excellent in curability by active energy rays, particularly curability by ultraviolet rays, and whose cured film is free from coloring and odor, and which is excellent in hardness, solvent resistance and water resistance. Intensive studies were conducted to find an aqueous emulsion suitable for OPV and paint applications.

[0010]

Means for Solving the Problems The present inventors have conducted various studies to solve the above-mentioned problems, and as a result, a polymer having an imide (meth) acrylate having a specific structure as a constituent monomer unit has An emulsion comprising a compound having two or more (meth) acryloyl groups was found to be effective, and the present invention was completed. Hereinafter, the present invention will be described in detail. still,
In the present specification, an acryloyl group and / or a methacryloyl group is a (meth) acryloyl group, and an acrylate and / or a methacrylate is a (meth) acrylate.
Acrylic acid and / or methacrylic acid are referred to as (meth) acrylic acid.

(A) Polymer The polymer of the component (A) of the present invention is a compound having an ethylenically unsaturated group and a cyclic imide group represented by the following general formula (1) (hereinafter simply referred to as an imide compound). Is a constituent monomer unit.

[0012]

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[However, in the formula (1), R ¹ and R
² is an independent hydrogen atom or an alkyl group having 4 or less carbon atoms, one of them is a hydrogen atom and the other is an alkyl group having 4 or less carbon atoms, or a group that forms a carbocyclic ring together. ]

Examples of the ethylenically unsaturated group in the imide compound include a vinyl group and a (meth) acryloyl group, and a (meth) acryloyl group is preferable. R ¹ and R ² are each independently an alkyl group having a carbon number of 4 or less, or R ¹ and R ² each independently represent an alkyl group having a carbon number of 4 or less, because of their excellent polymerizability or copolymerizability with an ethylenically unsaturated group-containing monomer. Groups which together form a carbocycle are preferred. Further, the production of imide compounds is easy, the yield is excellent, and the obtained copolymer is excellent in water resistance. Group —CH ₂ CH ₂ CH ₂ — or group —CH ₂ CH ₂ CH ₂ C
H ₂ — is preferred, particularly preferably the group —CH ₂ CH ₂ CH ₂
CH ₂ —.

The polymer used in the present invention has the above formula (1)
Since it has a maleimide group shown in the above, it is easily cured by active energy rays, and even when it is cured by ultraviolet rays, it has excellent curability with no photopolymerization initiator or with a small amount of photopolymerization initiator. The cured product has excellent physical properties.

As the imide compound, the following general formula (2)
The imide (meth) acrylate represented by is preferred.

[0017]

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However, in the formula (2), R ¹ and R ² are
Each is an independent hydrogen atom or an alkyl group having 4 or less carbon atoms, one of which is a hydrogen atom and the other is an alkyl group having 4 or less carbon atoms, or a group which forms a carbon ring together with one. R ³ is an alkylene group having 1 to 6 carbon atoms, R ⁴ is a hydrogen atom or a methyl group, and n is 1 to 6
Is an integer.

In the above formula (2), n is preferably from 1 to 2, more preferably 1, because the obtained copolymer has excellent curability. As R ¹ and R ² ,
The same as above is preferred. R ³ is an alkylene group having 1 to 6 carbon atoms, and preferable examples include an ethylene group and a propylene group.

Preferred examples of the imide (meth) acrylate include compounds represented by the following formulas (3) and (4).

[0021]

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However, in the formula (3), R ⁴ and R ⁵ are a hydrogen atom or a methyl group. n is an integer of 1 to 6.

[0023]

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In the formula (4), R ⁴ and R ⁵ are a hydrogen atom or a methyl group, and R ⁶ and R ⁷ are an alkyl group having 4 or less carbon atoms. n is an integer of 1 to 6.

The imide (meth) acrylate can be produced from an acid anhydride, an amino alcohol and (meth) acrylic acid by a method described in the following documents and patents. -Kiyoshi Kato et al., Journal of the Society of Synthetic Organic Chemistry, 30 (10), 89
7, (1972)-Javier de Abajo et al., Polymer, vol33.
(5), (1992)-JP-A-56-53119, JP-A-1-2425
No. 69 As acid anhydride used as a production raw material, 3,4,4
5,6-tetrahydrophthalic anhydride and derivatives thereof,
Dialkylmaleic anhydride and its derivatives. From the viewpoint of excellent yield, 3,4,5,6-tetrahydrophthalic anhydride and its derivatives are preferred. Examples of the amino alcohol used as a raw material include alkanolamines such as ethanolamine, propanolamine and butanolamine, and 2,2'-aminoethoxyethanol.

As the component (A), even if it is a homopolymer of imide (meth) acrylate, it may be an imide (meth) acrylate and an ethylenically unsaturated group-containing monomer copolymerizable therewith (hereinafter referred to as an unsaturated monomer). Copolymers).

Various unsaturated monomers can be used as long as they are other than imide (meth) acrylate.
For example, styrene, α-methylstyrene, (meth) acrylonitrile, vinyl acetate, (meth) acrylic acid, (meth) acrylate and the like can be mentioned. Specific examples of (meth) acrylate include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate; cyclohexyl Alicyclic (meth) acrylates such as (meth) acrylate and isobornyl (meth) acrylate; aryl (meth) acrylates such as benzyl (meth) acrylate; 2-methoxyethyl (meth) acrylate and 2-ethoxyethyl (meth) acrylate And the like, and hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate. Because of the excellent stability of the resulting emulsion,
As the unsaturated monomer, (meth) acrylic acid is preferred. When the unsaturated monomer is copolymerized, the copolymerization ratio is preferably 0.1% by weight or more, more preferably 1% by weight or more based on all monomers.

In the component (A), the particle size of the polymer is preferably 0.01 to 0.50 μm, more preferably 0.05 to 0.25 μm in terms of weight average particle size. If the weight average particle size is less than 0.01 μm, it may not be possible to produce an emulsion having a high solid content, while 0.50 μm
If it exceeds 30, the stability of the emulsion may decrease. Incidentally, in the present invention, the weight average particle size is Δn
d ⁴ / Σnd ³ (n represents the number of particles and d represents the particle size).

The component (A) can be produced by various methods, as long as the above monomer is produced by conventional solution polymerization and emulsion polymerization, and emulsion polymerization is preferred. As a specific method of emulsion polymerization, a raw material monomer to be used is dispersed in an aqueous medium using an emulsifier, and the mixture is heated and stirred in the presence of a polymerization initiator, and the raw material monomer to be used is aqueous. A method in which an aqueous emulsion is dispersed by using an emulsifier in a medium, and the aqueous emulsion is heated and stirred in the presence of a polymerization initiator while being added to the aqueous medium. If necessary, a chain transfer agent can be used to adjust the molecular weight of the polymer. The type and ratio of the emulsifier and the polymerization initiator used in the emulsion polymerization, the applied polymerization temperature and the method of supplying the monomer may be appropriately selected depending on the monomer used and the purpose. As the polymerization temperature, a polymerization temperature suitable for a commonly used polymerization initiator is employed.

Examples of the polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, hydrogen peroxide,
Peroxides such as benzoyl peroxide and t-butyl hydroperoxide; These may be used in combination with a reducing agent such as sodium bisulfite and ascorbic acid and used as a redox initiator. Among these, a water-soluble polymerization initiator is preferable.

Examples of the emulsifier include anionic surfactants such as sodium dialkyl sulfosuccinate, sodium dodecylbenzene sulfonate, sodium lauryl sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate and sodium alkyl diphenyl ether disulfonate; Nonionic surfactants such as alcohol ethers and polyoxyethylene alkyl phenyl ethers are included. Further, in order to improve the stability of the emulsion and the water resistance of the cured coating film, anionic emulsifiers such as polycarboxylic acid and polysulfonic acid, nonionic polymer surfactants such as polyvinyl alcohol, and acryloyl A reactive surfactant having a radically polymerizable group such as a group, an allyl group and a propenyl group can also be used. Two or more emulsifiers can be used in combination. As the mixing ratio of the emulsifier,
The amount is preferably 0.05 to 5 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the monomer used. If the proportion of the emulsifier is less than 0.05 part by weight, the stability of the obtained emulsion may be reduced, while if it exceeds 5 parts by weight, the water resistance may be reduced. Examples of the method of adding the emulsifier include a method of adding the whole amount at the time of polymerization or after the polymerization, a method of adding a part at the time of the polymerization, and a method of adding the rest after the polymerization. When a reactive surfactant is used as an emulsifier, it is preferable to add the whole amount during polymerization.

Examples of the chain transfer agent include dodecyl mercaptan, xanthate disulfide, diazothioether and 2-propanol.

(B) Compound having two or more (meth) acryloyl groups The emulsion of the present invention comprises the polymer (A) and the polymer (B)
It comprises a compound having two or more (meth) acryloyl groups. By using the component (B) in combination, the curability of the emulsion and the hardness of the obtained cured product can be improved.

Examples of the component (B) include acrylic monomers and oligomers. Examples of acrylic monomers include alkylene glycol di (meth) acrylates such as ethylene glycol di (meth) acrylate and propylene glycol di (meth) acrylate; diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tetra Low molecular weight polyalkylene glycol di (meth) acrylates such as ethylene glycol di (meth) acrylate and tripropylene glycol di (meth) acrylate or alkylene oxide modified products thereof; trimethylolpropane tri (meth) acrylate, pentaerythritol di,
Polyalkylene glycol poly (meth) acrylates such as tri- or tetra (meth) acrylate and dipentaerythritol penta- or hexaacrylate; alkylene oxide modified polyarlequin glycol poly (meth) acrylate; and alkylene oxide modified isocyanurate And di (meth) acrylates.

Examples of the acrylic oligomer include urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate and polyether polyol.

Examples of the urethane (meth) acrylate oligomer include a reaction product obtained by further reacting a hydroxyl group-containing (meth) acrylate with a polyol and an organic polyisocyanate reaction product. Here, examples of the polyol include low-molecular-weight polyols, polyethylene glycol and polyester polyol, and examples of the low-molecular-weight polyol include ethylene glycol, propylene glycol, cyclohexanedimethanol, and 3-methyl-1,5-pentanediol. And polyether polyols such as polyethylene glycol and polypropylene glycol. Polyester polyols include these low molecular weight polyols and / or polyether polyols and adipic acid, succinic acid, phthalic acid, hexahydrophthalic acid and terephthalic acid. And a reaction product with an acid component such as a dibasic acid or an anhydride thereof. Examples of the organic polyisocyanate include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Examples of the hydroxyl group-containing (meth) acrylate include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate.

Examples of the polyester (meth) acrylate oligomer include a dehydration condensate of a polyester polyol and (meth) acrylic acid. As the polyester polyol, ethylene glycol, polyethylene glycol, cyclohexanedimethanol, 3-methyl-
Low molecular weight polyols such as 1,5-pentanediol, propylene glycol, polypropylene glycol, 1,6-hexanediol and trimethylolpropane, and polyols such as alkylene oxide adducts thereof, and adipic acid, succinic acid, phthalic acid, A reaction product from a dibasic acid such as hexahydrophthalic acid and terephthalic acid or an acid component such as an anhydride thereof is exemplified.

Epoxy acrylate is obtained by subjecting an epoxy resin to an addition reaction with an unsaturated carboxylic acid such as (meth) acrylic acid. Epoxy (meth) acrylate of bisphenol A type epoxy resin, phenol or epoxy of cresol novolac type epoxy resin is used. (Meth) of diglycidyl ether of (meth) acrylate and polyether
Acrylate and the like.

Examples of the polyether polyol include polyethylene glycol di (meth) acrylate and polypropylene glycol di (meth) acrylate, and alkylene oxide modified products thereof.

Other components A compound having one ethylenically unsaturated group may be further added to the emulsion of the present invention for the purpose of adjusting the curability and the adhesion and hardness of the cured product. Examples of the compound having one ethylenically unsaturated group include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; and phenol alkylene such as phenoxyethyl (meth) acrylate. (Meth) acrylate of oxide adduct or its halogen nucleus substituted product; ethylene glycol mono (meth) acrylate, methoxyethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate and tripropylene glycol mono (meth) acrylate Glycol-mono (meth) acrylates; N-vinyl compounds such as N-vinylpyrrolidone and N-vinylcaprolactam;

The emulsion of the present invention is crosslinked and cured by irradiation with an active energy ray. Since the polymer used has a maleimide group as described above, it is easily cured by the active energy ray and further cured by ultraviolet rays. Even in such a case, even if no photopolymerization initiator is added or a small amount of the photopolymerization initiator is added, the composition has excellent curability.

When the photopolymerization initiator is mixed, benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether and its alkyl ether; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxyacetophenone, 1-hydroxycyclohexylphenylketone and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane Acetophenones such as -1-one; anthra such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone and 2-amylanthraquinone; Non; thioxanthones such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone and 2,4-diisopropylthioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone; And xanthones. These photopolymerization initiators can be used alone or in combination with a benzoic acid-based or amine-based photopolymerization initiator. The photopolymerization initiator is
It is preferable to add 0.1 to 10% by weight in the emulsion.

In the emulsion, if necessary, fillers such as barium sulfate, silicon oxide, talc, clay and calcium carbonate; coloring pigments such as phthalocyanine blue, phthalocyanine green, titanium oxide and carbon black; Various additives such as a property imparting agent and a leveling agent, and polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, phenothiazine and aluminum N-nitrosophenylhydroxylamine can also be blended. When these are compounded, the mixing ratio is preferably 100 parts by weight or less based on 100 parts by weight of the polymer. When the polymerization inhibitor is compounded, the mixing ratio is 10 wtppm in the emulsion.
It is preferably about 2% by weight.

Production Method The emulsion of the present invention comprises a polymer (A) and a polymer (B)
A compound having two or more (meth) acryloyl groups as components is dispersed in an aqueous medium. In the emulsion of the present invention, the ratio of the component (A) is 20% based on the total amount of the components (A) and (B).
９９99.9 parts by weight, preferably 20-60 parts by weight. The proportion of the component (B) is from 80 to 0.1 part by weight, preferably from 80 to 40 parts by weight, based on the total amount of the components (A) and (B). If the proportion of the component (A) is less than 20 parts by weight, the stability of the emulsion will be reduced, while if it exceeds 99.9 parts by weight, the curability and the hardness of the cured film will be reduced.

(A) and (B) in the emulsion
The proportion of the components is preferably from 30 to 70% by weight, more preferably from 40 to 60% by weight. This ratio is 3
If the amount is less than 0% by weight, it may be difficult to adjust the film thickness, it may take time to dry the substrate after coating, or the drying may be insufficient. If it exceeds, the emulsion may become unstable.

As a method for producing the emulsion of the present invention, the components (A) and (B) may be mixed in an aqueous medium according to a conventional method.
A method of adding and mixing the component (B) into the aqueous dispersion of the components with stirring is preferred because the stability of the finally obtained emulsion is excellent. When a polymer having (meth) acrylic acid as a constituent monomer unit is used as the component (A), the emulsion is further stabilized by adjusting the pH of the emulsion. Preferably, a compound is added.

When the photopolymerization initiator is added to the emulsion of the present invention, the photopolymerization initiator may be
When added to the aqueous dispersion of the component (A) or the component (A),
Even if it is added to and dissolved in the component (B), it may be added to the emulsion. In the case of a photopolymerization initiator which is solid and has particularly low solubility in water, it is preferable to add and dissolve it in the component (B) because the photopolymerization initiator has excellent solubility.

Applications and methods of use The emulsion of the present invention can be used for various applications such as coating materials such as paints, coating agents and printing inks, binders for nonwoven fabrics, adhesives, fillers, molding materials and resists. , And can be preferably used as a coating material, and can be more preferably used as a coating material for OPV and wood.

The active energy rays used for curing the emulsion include ultraviolet rays, X-rays, and electron beams, and it is preferable to use ultraviolet rays because an inexpensive apparatus can be used. Various light sources can be used as a light source for curing with ultraviolet light, and examples thereof include a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, an electrodeless discharge lamp, and a carbon arc lamp.

The emulsion of the present invention can be suitably used as a coating material (hereinafter referred to as a coating composition). In this case, if necessary, the composition may contain a synthetic resin such as an acrylic resin, a ketone resin and a petroleum resin, an inorganic or organic extender, a matting agent, a filler such as a sanding aid, a leveling agent, and a pigment dispersion. Various additives such as an agent, a gloss imparting agent, a slip agent, and a thixotropic agent may be blended.

As the substrate to which the coating composition can be applied,
Wood such as natural wood and synthetic wood, polycarbonate,
Molded resin processed products (plastics) such as polymethyl methacrylate and polyvinyl chloride, paper, metal, glass, concrete, and the like. When the emulsion of the present invention is used as a paint, the emulsion is excellent in adhesiveness, and thus is suitably used particularly as a wood paint. The method for using the coating composition may be a conventional method, such as a method in which the composition is applied to a substrate, dried by heating, and then irradiated with an active energy ray. As a coating method, a conventionally known method such as a roll coater, a flow coater, spraying, dipping, and brush coating may be used. The composition comprising the aqueous dispersion of the present invention has a low viscosity and is particularly suitable as a coating composition for flow coater, spraying and dipping. It is preferable that the coating applied to the substrate is sufficiently dried by heating because the cured coating has excellent strength and transparency. The irradiation method of the active energy ray may be in accordance with a conventional method.

The emulsion of the present invention can be preferably used as OPV (hereinafter referred to as OPV composition). As the base material in this case, plain paper containing cellulose as a main component, films and sheets of polyethylene, polyvinyl chloride, polypropylene, polyester, polycarbonate, polyimide, or the like, or paper and the like treated with these, and these base materials And the like, whose surface is printed with various inks.

The OPV composition can be used in the same manner as the above-mentioned coating composition. In the composition for OPV, as a method of applying to a substrate, it can be applied by printing, in addition to direct coating. In the case of direct coating, curtain flow coating, roll coating, spray coating and the like can be mentioned. Since the composition for OPV of the present invention is a low-viscosity composition, coating by spray coating is also possible. In the case of printing, it is sufficient to follow a normal printing method, and an offset method, a gravure offset method,
A gravure method and a flexo method are exemplified.

[0054]

The aqueous emulsion of the present invention is one in which the maleimide groups in the polymer undergo a cross-linking reaction between the molecules upon irradiation with active energy rays, thereby exhibiting excellent cured film properties. It is known from JP-A-52-988 and JP-A-55-160010 that a polymer having a maleimide group undergoes a crosslinking reaction upon irradiation with ultraviolet rays.
By using a compound having two or more (meth) acryloyl groups as the component (B), the resulting cured film can have excellent hardness, water resistance and solvent resistance. Furthermore, the emulsion of the present invention can be easily cured by active energy rays, and even when cured by ultraviolet rays, excellent curability can be obtained by blending no photopolymerization initiator or blending a small amount of photopolymerization initiator. Have This is because the maleimide group causes a hydrogen abstraction reaction by ultraviolet irradiation and generates radicals.
onny Jonsson et al., Radotech '95 Europe Preliminary Lecture <Academic Day> p. 34) etc., the maleimide group of the polymer in the present invention also generates radicals by the same mechanism without the addition of a photopolymerization initiator, and together with the crosslinking reaction between the maleimide groups,
Because the (meth) acryloyl group of the component (B) is polymerized,
Excellent curability can be obtained by adding no photopolymerization initiator or adding a small amount of photopolymerization initiator. As a result, the amount of the photopolymerization initiator in the emulsion can be reduced or eliminated, so that coloring and odor of the cured film can be reduced.

[0055]

The present invention will be described more specifically with reference to the following Examples and Comparative Examples. In the following, “parts” and “%” are based on weight. The meanings of the abbreviations of the monomers and photopolymerization initiators used are as follows. MMA: methyl methacrylate BA: butyl acrylate MAA: methacrylic acid TPGDA: tripropylene glycol diacrylate [Aronix M220 manufactured by Toagosei Co., Ltd.] PETA: pentaerythritol triacrylate [Aronix M305 manufactured by Toagosei Co., Ltd.] -TMP (EO) TA; trimethylolpropane ethylene oxide 3 mol modified triacrylate [Aronix M350 manufactured by Toagosei Co., Ltd.]-BDK: benzyl dimethyl ketal [Toagosei Co., Ltd.]
Aronix MC-101]

Production Examples 1 to 3 In a reactor equipped with a stirrer, a thermometer, a cooler, a nitrogen inlet tube and two dropping funnels, 57 parts of water and 0.7 parts of sodium lauryl sulfate were charged and charged. Temperature to 1 ° C
2.4 parts of a 3% aqueous ammonium persulfate solution and 3.3 parts of an 11% aqueous sodium carbonate solution were added. To 100 parts of the monomer mixture having the composition shown in Table 1, sodium lauryl sulfate was added in an amount of 0.1 mL.
7 parts and 40 parts of water were added and emulsified. The obtained aqueous emulsion was continuously dropped into the reactor over 3 hours from a dropping funnel, and emulsion polymerization was performed at 85 ° C. The mixture was further stirred at 85 ° C. for 1 hour after the completion of the dropwise addition, and then the system was cooled to terminate the polymerization. Aqueous dispersions A-1 to A-1 were prepared by adding 1.2 parts of 25% aqueous ammonia to the obtained aqueous dispersion of copolymer.
-3 was obtained. Table 1 shows various physical properties of the obtained aqueous dispersion. The weight average particle diameter (hereinafter simply referred to as particle diameter) is
It was measured by a laser diffraction / scattering type particle size distribution analyzer LA-910 manufactured by Horiba, Ltd. The viscosity was measured at 60 rpm using a B-type viscometer (unit: mPa · s / 25 ° C.).

[0057]

[Table 1]

1) Imidoacrylate represented by the following formula (5)

[0059]

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2) Imido methacrylate represented by the following formula (6)

[0061]

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Comparative Production Example 1 An aqueous dispersion of a copolymer was obtained in the same manner as in Production Example except that the monomers shown in Table 2 were used. The physical properties of the obtained aqueous dispersion were measured in the same manner as in Production Examples. Table 2 shows the results.

[0063]

[Table 2]

Examples 1 to 4 A compound having two or more (meth) acryloyl groups was added to and mixed with an aqueous dispersion of a copolymer in the proportions shown in Table 3 to obtain an emulsion. The obtained emulsion was evaluated according to the following. Table 4 shows the results.

Evaluation The obtained emulsion was applied on a bonderite steel sheet PB-144 (manufactured by Nippon Test Panel Co., Ltd.) using a bar coater # 10, and heated in a dryer at 80 ° C. for 5 minutes to apply. Water was removed from the membrane. Then, under the following conditions,
The coating was repeatedly passed four times under an ultraviolet lamp. UV irradiation conditions; Lamp: 120 W / cm condensing high-pressure mercury lamp Lamp height: 10 cm Conveyor speed: 5 m / min The obtained cured films were evaluated in the following (1) to (4).

(1) Solvent resistance Using a cotton swab impregnated with acetone, a load of 500
g, the surface of the cured film obtained under the condition of one reciprocation per second was rubbed, and the number of times until the surface of the cured film caused an abnormality such as whitening or peeling was evaluated in the following three grades. ○: No abnormality in cured film after 20 reciprocations △: Abnormality in cured film after 10 reciprocations and less than 20 reciprocations ×: Abnormality in cured film after less than 10 reciprocations

(2) Water resistance The obtained cured film was immersed in warm water of 80 ° C. for 1 hour.
After drying at 60 ° C. for 2 hours, the surface condition was visually observed and evaluated according to the following three grades. ：: No abnormality Δ: Slight peeling and / or whitening occurred X: Clear peeling and / or whitening occurred

(3) Pencil Hardness The obtained cured film was subjected to JIS “Hand-drawing method K540”.
0 ".

(4) Odor The smell of the cured film immediately after curing was smelled and evaluated according to the following three grades. ：: No odor at all, わ ず か: Slight odor, ×: Odor

[0070]

[Table 3]

[0071]

[Table 4]

Comparative Examples 1 to 3 Example 1 was repeated except that raw materials of the types and amounts shown in Table 5 were used.
An emulsion was produced in the same manner as described above. The obtained emulsion was evaluated in the same manner as in the examples. Table 6 shows the results. In Comparative Example 1, the coating film after drying of the emulsion was evaluated without irradiation with ultraviolet rays.

[0073]

[Table 5]

[0074]

[Table 6]

Examples 4, 5 and Comparative Example 4 (Composition for OPV) To 100 parts of the emulsions of Examples 1, 2 and Comparative Example 2 were added 1 part of a fluorinated leveling agent for OPV. A composition was prepared. The obtained composition for OPV was evaluated according to the following. The results are shown in Tables 7 and 8.

Evaluation The curing was carried out under the same conditions as in Examples 1 to 3 except that coated paper was used as the base material instead of the bonderite steel sheet. With respect to the obtained cured film, the following evaluations (1) to (3) were performed.

(1) Adhesion A cross cut was made on the obtained cured film with a cutter knife, and a commercially available cellophane tape (manufactured by Nichiban Co., Ltd.) was pressed on the surface of the cured film, and the cured film was peeled off. Was evaluated in the following three stages. ：: No peeling △: Part of the surface on which the tape was affixed ×: The entire surface with the tape affixed

(2) Gloss The gloss was measured at 60 degrees using a gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd.).

(3) Water resistance, solvent resistance and odor Evaluation was made in the same manner as in Examples 1 to 3.

[0080]

[Table 7]

[0081]

[Table 8]

Examples 6 and 7 and Comparative Example 5 (Woodwork paint composition) Woodwork paints were prepared by adding 1 part of a fluorine-based leveling agent to 100 parts of the emulsions of Examples 1, 2 and Comparative Example 2. A composition was prepared. The obtained woodwork coating composition was evaluated according to the following. The results are shown in Tables 9 and 10.

Evaluation The curing was carried out under the same conditions as in Examples 1 to 3 except that a blank plate was used as the substrate instead of the bonderite steel plate. With respect to the obtained cured film, the following evaluations (1) to (3) were performed.

(1) Adhesion The obtained cured film was cut into a grid with a width of 2 mm by a cutter knife to form 100 square sections, and a commercially available cellophane tape (manufactured by Nichiban Co., Ltd.) was pressed on the surface. After being peeled off, it was indicated by the number of grids remaining.

(2) Pencil hardness Measured according to JIS K5400.

(3) Water resistance, solvent resistance and odor Evaluation was performed in the same manner as in Examples 1 to 3.

[0087]

[Table 9]

[0088]

[Table 10]

[0089]

The emulsion of the present invention is excellent in curability, and the cured film obtained is excellent in water resistance and solvent resistance, and further, is free of coloring and odor. It is useful in various industrial fields as a coating material, a bonding agent for nonwoven fabrics, an adhesive, a filler, a molding material and a resist, and can be suitably used as a coating material.
It is particularly useful as a coating for OPV and wood, and has extremely high industrial value.

Claims (4)

[Claims] 1. A polymer comprising (A) a compound having an ethylenically unsaturated group and a cyclic imide group represented by the following general formula (1) as a monomer unit, and (B) two or more (meth) ) An emulsion in which a compound having an acryloyl group is dispersed in an aqueous medium, wherein the proportion of the components (A) and (B) is from 20 to 99.9 based on the total amount of these components.
An active energy ray-curable aqueous emulsion which is 80 parts by weight and 80 to 0.1 parts by weight of the component (B). Embedded image [However, in the formula (1), R ¹ and R ² are each independently an alkyl group having 4 or less carbon atoms, one of them is a hydrogen atom and the other is an alkyl group having 4 or less carbon atoms, Or a group in which each forms a carbon ring. ] 2. The compound according to claim 1, wherein the compound having an ethylenically unsaturated group and the cyclic imide group represented by the general formula (1) is an imide (meth) acrylate represented by the following general formula (2). Active energy ray-curable aqueous emulsion. Embedded image [However, in the formula (2), R ¹ and R ² are each independently an alkyl group having 4 or less carbon atoms, or one of them is a hydrogen atom and the other is an alkyl group having 4 or less carbon atoms, Or a group in which each forms a carbon ring. R ³ is an alkylene group having 1 to 6 carbon atoms;
R ⁴ is a hydrogen atom or a methyl group. n is an integer of 1 to 6. ] 3. A composition for an active energy ray-curable overprint varnish comprising the aqueous emulsion according to claim 1 or 2. 4. An active energy ray-curable wood coating composition comprising the aqueous emulsion according to claim 1 or 2.