JP2000234045A - Aqueous composition of reactive copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous composition which is excellent in curability by an active energy ray and gives a cured film excellent in hardness and resistances to solvents and water by dispersing or dissolving a copolymer formed from an imide (meth)acrylate having a specific chemical structure and a monomer having an ethylenically unsaturated group and an acidic group or a salt of the copolymer in an aqueous medium. SOLUTION: The copolymer is formed from a monomer having an ethylenically unsaturated group and a cyclic imide group of the formula and a monomer having an ethylenically unsaturated group and an acidic group, and is excellent in curability by activation energy ray. In the formula, R1 and R2 are each independently 4C or lower alkyl or one of them is H and the other is 4C or lower alkyl provided they may combine with each other to form a carbocycle. Preferably, the copolymer has an acid value of 20-400 mgKOH/g. Preferably, the copolymer (salt) in an amount of 20-95 pts.wt. is compounded with 80-5 pts.wt. compound having at least two (meth)acryloyl groups in order to improve the curability of the objective aqueous composition and the hardness of a cured film obtained therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous composition of a reactive copolymer which can be cured by irradiation with an active energy ray such as an electron beam or an ultraviolet ray. It is useful for applications such as coating materials such as materials and printing inks, adhesives, fillers, molding materials, and resists, and is also useful as a coating material among them, especially overprint varnish (hereinafter referred to as OPV).
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 the reactive polymer curable with an active energy ray used as a base polymer aqueous. The following two methods are known as methods for making a reactive polymer aqueous. First, a polymer having a carboxyl group is produced by solution polymerization, and a compound having an epoxy group and an unsaturated group is added to the polymer to produce a reactive polymer having a carboxyl group. And suspending or emulsifying the neutralized polymer in water or an aqueous solution containing an organic solvent such as an alcohol (hereinafter referred to as "Method A", JP-A-51-17922, 51-23531). No.). There is also a method in which a polymer having a carboxyl group is produced in water in the presence of an emulsifier, and the obtained polymer is subjected to an addition reaction with a compound having an epoxy group and an unsaturated group (hereinafter referred to as "Method B"; -21
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] Further, in the application of paints, as a method for removing organic solvents, a method of using an ultraviolet-curable composition containing no organic solvent has been studied as described above. As the UV-curable coating composition, those comprising an oligoester (meth) acrylate such as polyester acrylate, epoxy acrylate and urethane acrylate and a reactive diluent are known. For example, JP-A-5-9
No. 247 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). −21195
No. 0).

[0006]

In the above method A, the reaction of adding a compound having an epoxy group and an unsaturated group to a polymer having a carboxyl group is carried out in an organic solvent having hydrophilicity such as alcohol or ketone. Although the reaction is carried out using a catalyst such as an organic amine, the reaction is insufficient in reactivity and requires a long time for the reaction. In order to increase the reactivity, there is a method of increasing the amount of a catalyst such as an organic amine.However, in this case, the catalyst forms a large amount of a salt with a polymer having a carboxyl group, and the resulting reactive weight is increased. It has the problem that the coalescence becomes difficult to dissolve in the solvent,
In addition, the obtained cured film may be colored due to the catalyst. When the obtained reactive polymer is converted to an aqueous solution, it is necessary to remove the organic solvent contained therein by evaporation or the like. However, it is difficult to completely remove the organic solvent from the reactive polymer, and therefore, there is a problem that the final product has an odor. In order to solve the problem of odor, if an attempt is made to evaporate the organic solvent as much as possible, it takes a long time to evaporate the organic solvent. As a result, the reactive polymer is exposed to an anaerobic atmosphere that promotes the curing reaction. Due to exposure for a long time, the storage stability of the final product may be deteriorated, or the product may be colored. In the case of Method B, the resulting reactive polymer aqueous dispersion contained a surfactant in the liquid, and thus the cured film of the reactive polymer had poor water resistance.

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 investigations were made to find an aqueous composition suitable for OPV and paint applications.

[0010]

Means for Solving the Problems The present inventors have conducted various studies in order to solve the above problems, and as a result, have found that imide (meth) acrylate and a monomer having an acidic group and an ethylenically unsaturated group are used. It has been found that an aqueous composition of a copolymer having a constituent monomer unit is effective, and that the dispersion is particularly effective for use in OPVs and paints, thereby completing the present invention. Hereinafter, the present invention will be described in detail. In the present specification, acrylate and / or methacrylate will be referred to as (meth) acrylate, and acrylic acid and / or methacrylic acid will be referred to as (meth) acrylic acid. The unit of acid value is mg
KOH / g, and its description is omitted below.

○ Copolymer or Salt Thereof The copolymer used in the aqueous composition 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 imide). (Hereinafter referred to as "compound") and a copolymer (hereinafter simply referred to as "copolymer") having a monomer containing an ethylenically unsaturated group and an acidic group (hereinafter referred to as "acidically unsaturated monomer") as constituent monomer units, or a salt thereof. It is.

Since the copolymer used in the present invention has a maleimide group represented by the following formula (1), it is easily cured by an active energy ray, and even when it is cured by an ultraviolet ray, no photopolymerization initiator is used. It has excellent curability when not mixed or with a small amount of a photopolymerization initiator, and the cured product has excellent physical properties.

[0013]

Embedded image

[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 —.

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

[0017]

Embedded image

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]

Embedded image

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.

The copolymer of the present invention comprises the imide (meth)
It is obtained by copolymerizing an acidic unsaturated monomer in addition to acrylate. By introducing an acidic group into the copolymer,
Self-dispersion of the copolymer in the aqueous medium becomes possible. In the acidic unsaturated monomer, examples of the acidic group include a carboxyl group, a sulfonyl group, and a phosphate group. Examples of the ethylenically unsaturated group include a vinyl group and a (meth) acryloyl group. Among these, unsaturated monomers having a carboxyl group are preferred in that the resulting aqueous composition is excellent in stability and the coating film is excellent in water resistance. Examples of the monomer include, for example, oligomers of dimer or more of (meth) acrylic acid, maleic acid, crotonic acid, itaconic acid, cinnamic acid, (meth) acrylic acid, and ω-carboxypolycaprolactone mono (meth) A) acrylate, monohydroxyethyl (meth) acrylate phthalate and monohydroxyethyl (meth) acrylate succinate. The copolymerization ratio of the acidic unsaturated monomer is preferably a ratio at which the acid value of the obtained copolymer satisfies the following preferable acid value.

The copolymer used in the present invention is, in addition to imide (meth) acrylate and an acidic unsaturated monomer, an ethylenically unsaturated group-containing monomer copolymerizable with these monomers, if necessary. (Hereinafter, referred to as other monomers).

As the other monomer, various ones other than imide (meth) acrylate and acidic unsaturated monomer can be used. For example, styrene, α-methylstyrene, (meth) acrylonitrile, acetic acid Vinyl and (meth) acrylate. 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. The copolymerization ratio of other monomers is preferably from 0 to 90% by weight, more preferably from 0 to 60% by weight.

The acid value of the copolymer is 20 to 400 m
gKOH / g is preferable, and more preferably 20 to 150 gKOH / g.
mg KOH / g. When the acid value is less than 20 mgKOH / g, the storage stability of the aqueous composition such as copolymer aggregation or precipitation may be reduced, while the acid value is 400 mgKOH / g. If the amount exceeds the above range, the water resistance and alkali resistance of the coating film may decrease. When lipophilic monomers such as hexyl (meth) acrylate, cyclohexyl (meth) acrylate and styrene are used as the monomer, 100 to 400 mgKOH / g
Is preferred.

The number average molecular weight of the copolymer is from 1,000 to
1,000,000 is preferred, and more preferably, 2.0
00 to 100,000. If this value is less than 1,000, the cured film may have insufficient adhesion and strength to the substrate, and on the other hand, if this value is 1,
When the amount is more than 1,000,000, the curability and the strength of the cured product become insufficient, or when a compound having two or more (meth) acryloyl groups described below is mixed with the aqueous composition, The compatibility with the compound having two or more (meth) acryloyl groups may decrease, and the stability of the aqueous composition may decrease. In the present invention, the number average molecular weight (hereinafter abbreviated as Mn) and weight average molecular weight
The term (hereinafter abbreviated as Mw) is a value obtained by converting the molecular weight measured by gel permeation chromatography (hereinafter abbreviated as GPC) using tetrahydrofuran as a solvent, based on the molecular weight of polystyrene.

The copolymer may be any one obtained by polymerizing the above monomers according to a conventional method, and examples thereof include solution polymerization, emulsion polymerization and suspension polymerization. Among them, those produced by a solution polymerization method are preferable in that various acidic unsaturated monomers can be used. Examples of a method for producing a copolymer by a solution polymerization method include a method in which a raw material monomer to be used is dissolved in an organic solvent, a thermal radical polymerization initiator is added, and the mixture is stirred under heating. If necessary, a chain transfer agent can be used to adjust the molecular weight of the polymer.

Examples of the thermal polymerization initiator used herein include peroxides, azo compounds, and redox polymerization initiators that generate radical species by heat. Examples of peroxides include benzoyl peroxide, lauroyl peroxide,
Cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide and the like. Examples of the azo compound include azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile. Examples of redox initiators include hydrogen peroxide-iron (II) salt, peroxodisulfate-sodium bisulfite, cumene hydroperoxide-iron (II) salt and the like. Examples of the organic solvent include benzene, toluene, ethyl acetate, methanol, dimethylformamide and the like. Examples of the chain transfer agent include dodecyl mercaptan, xanthate disulfide, diazothioether and 2
-Propanol and the like.

A method for producing an aqueous composition of a reactive copolymer As a method for producing an aqueous composition of a reactive copolymer, various methods can be used. For example, the copolymer is stirred into an aqueous medium while stirring. A method of adding, a method of neutralizing the copolymer with an alkaline compound to form a salt of the copolymer, and then adding the salt to an aqueous medium with stirring may be mentioned. As the copolymer, the organic solvent solution after copolymerization may be used as it is, or the organic solvent solution of the copolymer may be used as a solid or liquid copolymer in which the organic solvent has been removed in advance by distillation or reprecipitation. A polymer may be used. When using an organic solvent solution of the copolymer, it is preferable to disperse the organic solvent in an aqueous medium and then distill off the organic solvent under reduced pressure. In the present invention,
It is preferable to use a copolymer excluding the organic solvent, since the aqueous composition finally obtained in the present invention has almost no problems such as odor and coloring.

As described above, in the prior art method A, a polymer having a carboxyl group is produced by solution polymerization, and the polymer containing an epoxy group (meth) is added to the polymer in an organic solvent.
An acrylate or the like is subjected to an addition reaction, and thereafter, the solvent is removed and then dispersed in water to produce an aqueous composition of a reactive polymer. For this reason, a complicated manufacturing process was required, and the cured film was colored due to a catalyst in the addition reaction. On the other hand, the reactive copolymer of the present invention can produce the copolymer in one step, and the production can be simplified as compared with the method A, and thus the composition of the composition finally obtained can be obtained. The coloring of the cured film is reduced, and the stability of the aqueous dispersion is excellent.

When the acidic group of the copolymer is a carboxyl group, it is preferable to neutralize a part or all of the carboxyl group in the copolymer with an alkaline compound to form a salt of the copolymer. The resulting aqueous composition is excellent in stability. Examples of the alkaline compound include ammonia, organic amines, and inorganic bases such as sodium hydroxide and potassium hydroxide. Among these, ammonia or a low molecular weight organic amine is preferable because the film is evaporated and scattered from the coating film during drying, and the finally obtained coating film has excellent water resistance. Examples of low molecular weight organic amines include trialkylamines such as trimethylamine, triethylamine and tributylamine, and N, N-
Examples include hydroxyalkylamines such as dimethylethanolamine, N-methyldiethanolamine and triethanolamine.

The neutralization ratio of the copolymer is 30 to 100 mol% based on the total amount of carboxyl groups in the copolymer.
Is preferably neutralized. If this ratio is less than 30 mol%, the copolymer may be difficult to dissolve or disperse in the aqueous medium. Similarly, the addition ratio of the alkaline compound is preferably from 30 to 100 mol% based on the total amount of the carboxyl groups in the copolymer. If this proportion is less than 30 mol%, the copolymer may be difficult to dissolve or disperse in an aqueous medium as described above, while if it exceeds 100 mol%, ammonia or ammonia may be used as an alkaline compound. When an amine is used, an odor may remain in the obtained aqueous composition.

The proportion of the copolymer or its salt in the composition is preferably from 30 to 70% by weight, more preferably from 40 to 60% by weight. When compounding a compound having two or more (meth) acryloyl groups described below,
The proportion of the total amount of the copolymer or a salt thereof and the compound having two or more (meth) acryloyl groups is 30 to 70% by weight.
And more preferably 40 to 60% by weight.
If the amount is less than 30% 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. Above this, the composition may become unstable.

Other components It is preferable that the aqueous composition of the present invention contains a compound having two or more (meth) acryloyl groups for the purpose of improving the curability of the composition and the hardness of the cured film. . Examples of the compound having two or more (meth) acryloyl groups include monomers and oligomers.

Examples of the monomer include alkylene glycol di (meth) acrylates such as ethylene glycol di (meth) acrylate and propylene glycol di (meth) acrylate; diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, Low molecular weight polyalkylene glycol di (meth) such as dipropylene glycol di (meth) acrylate and tripropylene glycol di (meth) acrylate
Acrylate or its alkylene oxide modified product; trimethylolpropane tri (meth) acrylate, pentaerythritol di or tri (meth) acrylate or pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate and dipentaerythritol penta or hexa Examples thereof include polyol poly (meth) acrylates such as (meth) acrylates and alkylene oxide modified products thereof; and di- and tri (meth) acrylates of isocyanuric acid alkylene oxide modified products.

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

Examples of the urethane (meth) acrylate oligomer include a reaction product obtained by further reacting a polyol and an organic polyisocyanate reaction with a hydroxyl group-containing (meth) acrylate. 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.

The polyester (meth) acrylate oligomer includes 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 (meth) acrylate include polyalkylene glycol di (meth) acrylates such as polyethylene glycol di (meth) acrylate and polypropylene glycol di (meth) acrylate, and modified alkylene oxides thereof.

A copolymer or a salt thereof and two or more (meth)
The ratio of the compound having an acryloyl group is 5 to 5 respectively.
80 parts by weight and 95 to 20 parts by weight are preferred. When the amount of the copolymer or a salt thereof is less than 5 parts by weight or the compound having two or more (meth) acryloyl groups exceeds 95 parts by weight, the stability of the aqueous composition may be reduced. is there. Further, when the amount of the copolymer exceeds 80 parts by weight or the compound having two or more (meth) acryloyl groups is 2
If the amount is less than 0 parts by weight, the curability and the hardness of the cured film may be insufficient.

The aqueous composition of the present invention may optionally contain a compound having one ethylenically unsaturated group for the purpose of adjusting the curability and the adhesion and hardness of the cured film. Compounds having one ethylenically unsaturated group include 2-hydroxyethyl (meth) acrylate and 2
Hydroxyalkyl (meth) acrylates such as hydroxypropyl (meth) acrylate; (meth) acrylates of alkylene oxide adducts of phenols such as phenoxyethyl (meth) acrylate, or halogen nucleus substitutes thereof; ethylene glycol mono (meth) acrylate Mono (meth) acrylates of glycols such as methoxyethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate and tripropylene glycol mono (meth) acrylate; and N such as N-vinylpyrrolidone and N-vinylcaprolactam -Vinyl compounds and the like.

As a compounding method, a compound having two or more (meth) acryloyl groups and / or a compound having one ethylenically unsaturated group can be mixed with an aqueous composition or mixed with a copolymer solution. After dissolving and neutralizing as necessary, it may be dispersed in an aqueous medium.

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

When the photopolymerization initiator is mixed, benzoin and its alkyl ether such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl 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 benzoic acid-based and amine-based photopolymerization initiators. The ratio of the photopolymerization initiator is preferably 0.1 to 10% by weight in the composition.

As a method of adding the photopolymerization initiator, the photopolymerization initiator may be added and dissolved in a solution of the copolymer or may be added to the aqueous composition. 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 a copolymer solution. When a compound having two or more (meth) acryloyl groups is added to the composition, it is easy to dissolve and use the compound having two or more (meth) acryloyl groups. Therefore it is preferable.

Before the irradiation with the active energy ray, it is preferable to heat the coated surface to evaporate and disperse water as a dispersion medium and ammonia or an organic amine when an alkaline compound is used. This reduces the film strength and transparency when moisture remains in the cured film,
Further, it is possible to prevent the odor and the decrease in weather resistance when ammonia or organic amine remains in the cured film.

In the aqueous composition, if necessary, fillers such as barium sulfate, silicon oxide, talc, clay and calcium carbonate, and coloring pigments such as phthalocyanine blue, phthalocyanine green, titanium oxide and carbon black may be used. And various additives such as an adhesion-imparting agent and a leveling agent, and a polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, phenothiazine and aluminum N-nitrosophenylhydroxylamine. When these are blended, the blending ratio is preferably 100 parts by weight or less based on 100 parts by weight of the copolymer. When the polymerization inhibitor is blended, the blending ratio is 10 wtppm to 2% in the composition.
% By weight.

Use The aqueous composition of the reactive copolymer obtained according to the present invention comprises:
It can be cured by irradiation with an active energy ray such as an electron beam or an ultraviolet ray, and can be used as it is or can be used by mixing various components.

Uses of the aqueous composition of the present invention include coating materials such as paints, coating materials and printing inks, adhesives, fillers, molding materials, resists, etc., and are preferably used as coating materials, and more preferably. Is OPV and wood paint.

The active energy rays used for curing the composition include ultraviolet rays, X-rays, and electron beams. 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.

When the aqueous composition of the present invention is used as a coating material (hereinafter referred to as a coating material composition), if necessary,
Synthetic resins such as acrylic resin, ketone resin and petroleum resin,
Fillers such as inorganic or organic extenders, matting agents, sanding aids, etc., and various additives such as leveling agents, pigment dispersants, gloss-imparting agents, slip agents, and thixotropic agents may be blended.

As a 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, metal, glass, paper and the like can be mentioned. Since the aqueous composition of the present invention has excellent adhesion to wood, it can be suitably used particularly as a wood coating. Examples of the method of using the coating material composition include 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 of the present invention has a low viscosity and is particularly suitable as a coating composition for flow coater, spraying and dipping. The irradiation method of the active energy ray may be in accordance with a conventional method.

The aqueous composition of the present invention can be preferably used for 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.

[0060]

In the aqueous composition of the present invention, 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 physical properties. JP-A-52-988 and JP-A-55-988
Japanese Patent No. -160010 and the like suggest an aqueous dispersion of a polymer having a maleimide group, and discloses that this causes a cross-linking reaction by irradiating ultraviolet rays.
Since the copolymer used in the present invention is a self-dispersible copolymer which can be dispersed without using an emulsifier, the cured film has excellent water resistance. Furthermore, the composition of the present invention is easily cured by active energy rays, and even when cured by ultraviolet rays, has excellent curability with no photopolymerization initiator or with a small amount of photopolymerization initiator. It has. This is because the maleimide group causes a hydrogen abstraction reaction by ultraviolet irradiation and generates a radical.
Radtec '95 Europe Preliminary Lecture Collection <Academic Day> p. 34) etc., the maleimide group of the polymer in the present invention also generates radicals by the same mechanism even without the incorporation of a photopolymerization initiator, and causes a cross-linking reaction between the maleimide groups. Excellent curability can be obtained by adding no initiator or adding a small amount of a photopolymerization initiator. As a result, the amount of the photopolymerization initiator in the composition can be reduced or eliminated, so that coloring and odor of the cured film can be reduced.

[0061]

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 for the used monomers and solvents are as follows. MMA: methyl methacrylate BA: butyl acrylate MAA: methacrylic acid AA: acrylic acid PGM: propylene glycol monomethyl ether IPA: isopropanol TPGDA: tripropylene glycol diacrylate [Aronix M220 manufactured by Toagosei Co., Ltd.] TMP (EO) TA; 3 moles of ethylene oxide modified triacrylate of trimethylolpropane [Aronix M350 manufactured by Toagosei Co., Ltd.]

Example 1 In a flask equipped with a stirrer, a thermometer, and a cooler, 20.0 g of imide acrylate represented by the formula (5)
5.0 g, BA 20.0 g, MAA 5.0 g, PGM1
00g and 5.0 g of 2,2'-azobis (2-methylbutyronitrile) (hereinafter referred to as AMBN) were charged and uniformly dissolved. Thereafter, the temperature was raised to 85 ° C. for 2 hours at 95 ° C.
Stirred at C for 1 hour. The obtained copolymer had a number average molecular weight of 9,100 and a weight average molecular weight of 21,000. The copolymer solution was reprecipitated with methanol, and the copolymer was purified to obtain a white powder solid. The obtained copolymer before neutralization is designated as A-1. 10.0 g of A-1 was added to TPGDA 1
5.0 g, and triethylamine 0.59 g
Was added to neutralize the mixture, 25 g of water was added thereto, and the mixture was stirred to disperse the copolymer salt in water to obtain a milky white aqueous dispersion. The obtained aqueous composition was evaluated according to the following method. Table 3 shows the results.

Evaluation (1) Viscosity Measured using an E-type viscometer. The unit is mPa · s / 25 ° C. (2) Curability The obtained aqueous composition was bonded to a bonderite steel sheet PB-144 [Japan Test Panel Co., Ltd.] using a bar coater # 10.
And dried in an oven at 80 ° C. for 5 minutes to remove water from the coating film. Thereafter, the coating material was repeatedly passed under an ultraviolet lamp under the following conditions. UV irradiation conditions; Lamp: 120 W / cm condensing high-pressure mercury lamp Lamp height: 10 cm Conveyor speed: 5 m / min Curability was evaluated by the number of passes until the tack on the surface of the coating film disappeared. In addition, after the above-mentioned number of irradiations, the following (3) to (6) were evaluated for the cured film that had passed twice more.

(3) 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

(4) Water resistance After 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

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

(6) Odor The odor immediately after curing of the cured film was smelled, and the odor was evaluated. ：: No odor at all, わ ず か: Slight odor, ×: Odor

Examples 2 to 7 Copolymers before neutralization were produced in the same manner as in Example 1 except that the raw materials and the mixing ratios shown in Table 1 below were used. Table 1 shows the physical properties of the obtained copolymer before neutralization. Using the obtained copolymer before neutralization, an aqueous composition was produced in the same manner as in Example 1 except that the raw materials and the mixing ratio shown in Table 2 were used. However, in Example 7, A-1 of the copolymer before neutralization was used.
An aqueous composition was produced in the same manner as in Example 1 except that benzyl dimethyl ketal (Aronix C101 manufactured by Toagosei Co., Ltd.) was further added to 1.0 part of TPGDA and 15 parts of TPGDA. The resulting aqueous composition,
Evaluation was performed in the same manner as in Example 1. Table 3 shows the results.

[0069]

[Table 1]

1) Imidoacrylate represented by the following formula (5)

[0071]

Embedded image

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

[0073]

Embedded image

[0074]

[Table 2]

[0075]

[Table 3]

Example 8 In the same flask as in Example 1, 40.0 g of the imide acrylate of the formula (2), 40.0 g of MMA,
A20.0 g, IPA100 g and AMBN3.0 g were charged and uniformly dissolved. Thereafter, the temperature was raised and the mixture was stirred at 80 ° C. for 6 hours. 2.3 g of triethylamine was added to 20 g of the solution of the copolymer before neutralization to neutralize the solution.
After adding 0 g and dispersing the copolymer salt in water, IPA was distilled off under reduced pressure. At this time, water was also distilled off at the same time, and finally an aqueous composition having a solid content of 42% was obtained. The obtained aqueous composition was evaluated in the same manner as in Example 1. Table 6 shows the results.

Example 9 Polymerization was carried out in the same manner as in Example 8 except that the raw materials and the mixing ratio shown in Table 4 below were used. Using 20 g of the obtained solution of the copolymer before neutralization, 2 g of TPGDA, 2.2 g of triethylamine and 20 g of water, the copolymer salt was dispersed in water in the same manner as in Example 8, and then IPA was distilled off. As a result, an aqueous composition having a solid content of 39% was obtained. The obtained aqueous composition was evaluated in the same manner as in Example 1. Table 6 shows the results.

[0078]

[Table 4]

[0079]

[Table 5]

[0080]

[Table 6]

Comparative Example 1 Polymerization was carried out in the same manner as in Example 8, except that the raw materials and the mixing ratios shown in Table 7 below were used. The copolymer salt was dispersed in water in the same manner as in Example 8 except that 20 g of the obtained copolymer solution before neutralization was used and triethylamine and water in the proportions shown in Table 8 were used. Was distilled off to obtain an aqueous composition having a solid content of 40%. The obtained aqueous composition was evaluated in the same manner as in Example 1. Table 9 shows the results. In Comparative Example 1, since the copolymer did not have an unsaturated bond, ultraviolet irradiation was not performed, and the dried coating film of the aqueous composition was evaluated.

Comparative Example 2 A copolymer before neutralization was produced in the same manner as in Example 1 except that the raw materials and the mixing ratios shown in Table 7 below were used. 10.0 g of the obtained copolymer before neutralization and 1.0 g of benzyldimethyl ketal were dissolved in 20.0 g of TMP (EO) TA, and neutralized with 0.41 g of triethylamine.
30 g of water was added thereto, and the mixture was stirred to disperse the copolymer salt in water to obtain a milky white aqueous composition. The obtained aqueous composition was evaluated in the same manner as in Example 1. Table 9 shows the results. In Comparative Example 2, since the copolymer did not have an unsaturated bond, the coating film after drying of the aqueous composition was evaluated without irradiation with ultraviolet rays.

Comparative Example 3 In a flask similar to that of Example 1, MMA40.0 was added at room temperature.
g, BA 30.0 g, MAA 30.0 g, PGM130
g and 5.0 g of AMBN were charged and uniformly dissolved.
Thereafter, the temperature was raised and the mixture was stirred at 85 ° C. for 2 hours and at 95 ° C. for 1 hour to obtain a copolymer. After cooling the reaction solution to 40 ° C., glycidyl methacrylate (hereinafter referred to as GMA) 3
0.0 g, tetrabutylammonium bromide 1.3 g
And 0.07 g of hydroquinone were added thereto, followed by stirring at 95 ° C. for 6 hours to add GMA to the carboxyl group of the copolymer. The obtained copolymer was purified by reprecipitation in the same manner as in Example 1 to obtain a white powder solid. Let the obtained copolymer be A-12. After dissolving 10.0 g of A-12 and 1.0 g of benzyldimethyl ketal in 15.0 g of TPGDA and neutralizing with 0.75 g of triethylamine, 25 g of water was added thereto, followed by stirring to obtain a milky white aqueous composition. Obtained. The obtained aqueous composition was evaluated in the same manner as in Example 1. Table 9 shows the results.

[0084]

[Table 7]

[0085]

[Table 8]

[0086]

[Table 9]

O Examples 10, 11 and Comparative Example 4 (OP
Composition for V) To 100 parts of the aqueous compositions of Examples 1 and 2 and Comparative Example 3, 1 part of a fluorinated leveling agent was added to produce a composition for OPV. The obtained composition for OPV was evaluated as follows. Table 11 shows the results.

(1) Curability Curability was evaluated in the same manner as in Example 1 except that coated paper was used as the base material. The cured film after the curing test was further passed through an ultraviolet lamp twice, and the following evaluations (2) to (4) were performed.

(2) Adhesion A cross-cut was made on the obtained cured film with a cutter knife, a commercially available cellophane tape (manufactured by Nichiban Co., Ltd.) was pressed on the surface, 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

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

(4) Water resistance, solvent resistance and odor Evaluation was performed in the same manner as in Example 1.

[0092]

[Table 10]

[0093]

[Table 11]

Examples 10, 11 and Comparative Example 4 (Coating composition for wood) To 100 parts of the aqueous composition of Examples 1 to 2 and Comparative Example 3, 1 part of a fluorine-based leveling agent was added. A wood coating composition was produced. The obtained wood coating composition was evaluated according to the following. Table 13 shows the results.

(1) Curable Example 1 except that a veneer veneer was used as a substrate.
The curability was evaluated in the same manner as described above. The cured film after the curing test was further passed through an ultraviolet lamp twice, and the following evaluations (2) to (4) were performed.

(2) Adhesion The obtained cured film was cut in 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.

(3) Pencil hardness The pencil hardness was measured according to JIS K5400.

(4) Water resistance, solvent resistance and odor Evaluation was made in the same manner as in Example 1.

[0099]

[Table 12]

[0100]

[Table 13]

[0101]

The aqueous composition of the present invention has excellent curability,
The cured film obtained is excellent in hardness, water resistance and solvent resistance,
Furthermore, since it has no coloring and odor, it is useful in various industrial fields as a coating material, a coating material, a coating material such as a printing ink, an adhesive, a filler, a molding material, a resist, etc., and particularly useful as a coating material for OPV and wood. And its industrial value is extremely large.

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Claims (6)

[Claims] An ethylenically unsaturated group and a compound represented by the following general formula (1):
A compound having a cyclic imide group represented by and a copolymer or a salt thereof having a monomer having an ethylenically unsaturated group and an acidic group as a constituent monomer unit is dispersed or dissolved in an aqueous medium. Aqueous composition of the reactive copolymer. 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. An ethylenically unsaturated group and the general formula (1)
The aqueous composition according to claim 1, wherein the compound having a cyclic imide group represented by the formula is an imide (meth) acrylate represented by the following general formula (2). 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. An acid value of the copolymer is 20 to 400 mgK.
3. The aqueous composition according to claim 1, wherein the aqueous composition is OH / g. 4. An aqueous medium comprising 20 to 95 parts by weight of the copolymer or a salt thereof according to claim 1 and 80 to 5 parts by weight of a compound having two or more (meth) acryloyl groups. The aqueous composition according to any one of claims 1 to 3, which is dispersed or dissolved therein. 5. An active energy ray-curable overprint varnish composition comprising the aqueous composition according to any one of claims 1 to 4. 6. An active energy ray-curable wood coating composition comprising the aqueous composition according to any one of claims 1 to 4.