JPH11279240A - Photo-curing resin composition and coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject composition having improved surface-curability of a coating film while keeping the flexibility, causing little yellowing of a coating film with time after curing, having low viscosity to be usable as a solventless coating composition and producible at a low cost by compounding a specific urethane compound with a photo-polymerizable monomer and a photo- polymerization initiator. SOLUTION: This composition contains (A) a urethane compound having unsaturated double bonds at both terminals and produced by reacting (i) an isocyanate compound having two isocyanate groups (preferably xylylene diisocyanate, or the like), (ii) a polyoxytetramethylene glycol compound having a number-average molecular weight of 300-1,300, (iii) a glycol compound expressed by formula I ((a) is an integer of >=1; R is H or methyl; the molecular weight is >=62; the number-average molecular weight is <=700) or formula III ((b) to (d) are each an integer of >=1; the number-average molecular weight is 300-1,000) and (iv) an ethylenic unsaturated compound containing hydroxyl group, (B) a photo-polymerizable monomer and (C) a photo-polymerization initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable resin composition useful as a coating curable by irradiation with ultraviolet rays or electron beams, and a coating using the same. In particular, it can be used as a solventless type with a low viscosity, the yellowing with time of the coating film after curing is small, the curability of the coating film surface, the elongation of the cured film,
The present invention relates to a photocurable resin composition and a paint having excellent tensile strength.

[0002]

2. Description of the Related Art In recent years, resin compositions curable by irradiation with ultraviolet rays or electron beams have been developed and used for coatings for coatings, adhesives, adhesives and the like. Among such resin compositions, urethane acrylates are described, for example, in JP-A-50-66596, JP-A-50-94090, JP-A-48-25095, and JP-A-64-2.
Many are known from, for example, US Pat. In recent years, for the purpose of improving productivity, the use in coating applications has increased, and the required characteristics thereof have also been diversified. Above all, there is an increasing demand for photocurable resin compositions and paints in which the cured coating film has flexibility, is excellent in curability, and has little yellowing over time after curing. However, considering the handleability and giving priority to low viscosity, the elongation of the cured coating film decreases, and increasing the molecular weight to improve the elongation of the cured coating film reduces the surface curability of the coating film and increases the resin There was a problem that the viscosity also increased.

[0003]

SUMMARY OF THE INVENTION The inventions described in claims 1 to 4 improve the surface curability of a coating film while maintaining good elongation and breaking strength, ie, flexibility. The present invention relates to a photocurable resin composition which has little yellowing over time, has a low viscosity and can be used as a solventless type, and can be provided with a low-cost material. Further, the invention according to claim 5 improves the surface curability of the coating film while maintaining good elongation and breaking strength, that is, flexibility, and reduces the time-dependent yellowing of the coating film after curing, The present invention relates to a paint which has a viscosity and can be applied as a solventless type, and which can be provided with a low-cost material.

[0004]

That is, the present invention provides an isocyanate compound (a) having two isocyanate groups in one molecule, a polyoxytetramethylene glycol compound (b) having a number average molecular weight of 300 to 1300, and a compound represented by the general formula: I)

Embedded image (Where a is an integer of 1 or more, R is a hydrogen atom or a methyl group, and has a molecular weight of 62 or more and a number average molecular weight of 700 or less) or a general formula (II)

Embedded image (Where b, c, and d are integers of 1 or more and the number average molecular weight is 300 to 1000), and the ethylenically unsaturated compound (d) having a hydroxyl group is reacted with the glycol compound (c). Urethane compound having unsaturated double bonds at both ends (A), photopolymerizable monomer (B) having one or more photocurable unsaturated double bonds in one molecule, and photopolymerization The present invention relates to a photocurable resin composition containing an initiator (C).

In the present invention, the ratio of each component in the above-mentioned reaction for obtaining the urethane compound (A) having an unsaturated double bond at both ends is determined by adjusting the ratio of the hydroxyl group-containing unsaturated compound (e) to
When the number of moles of the hydroxyl group present therein is 2, the number of moles of the isocyanate compound (a) is 2 to 6,
The total of the hydroxyl groups present in the polyoxytetramethylene glycol compound (b), the glycol compound (c) and the ethylenically unsaturated compound having a hydroxyl group (d) with respect to one equivalent of the isocyanate group of the isocyanate compound (a). Is from 1 to 1.1 equivalents. In the present invention, the isocyanate compound (a) is selected from isophorone diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, trimethylhexamethylene diisocyanate, and tetramethyl xylylene diisocyanate.
A photocurable resin which is a kind or two or more kinds of compounds (a1), or which comprises the above (a1) and tolylene diisocyanate (a2) in a molar ratio of (a2) / (a1) ≦ 2.5 Composition.

[0006] The present invention also relates to the urethane compound (A) having an unsaturated double bond at both ends, wherein the number average molecular weight is:
The present invention relates to a photocurable resin composition having a molecular weight of 1,000 to 4,000. Further, in the present invention, the weight ratio of the urethane compound (A) having an unsaturated double bond at both ends to the photopolymerizable monomer (B) is (A) / (C) in a ratio of 25/75 to 5/25. / 95, and relates to a photocurable resin composition wherein the photopolymerization initiator (C) is 1 to 10% by weight based on the total amount of the components (A) and (B). The present invention also relates to a paint containing the photocurable resin composition.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The diisocyanate compound (a) having two or more isocyanate groups in one molecule used in the present invention includes xylylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethyl Xylylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and the like.

Among these, considering the handling properties of the obtained urethane compound (A) having an unsaturated double bond at both ends, isophorone diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate,
One or more compounds (a1) selected from trimethylhexamethylene diisocyanate and tetramethylxylylene diisocyanate, or (a)
Those containing 1) and tolylene diisocyanate (a2) at a blending molar ratio of (a2) / (a1) ≦ 2.5 have low viscosity and thixotropy, and can make the cured coating film yellow-resistant. Ideal for When the molar ratio is more than 2.5, thixotropic properties appear in the resin and handling is reduced, and the cured coating film is liable to yellow over time.

In the present invention, a polyoxytetramethylene glycol compound (b) is used as the glycol component.
Which has a number average molecular weight of 300 to 1300. If the number average molecular weight is less than 300, sufficient elongation of the coating film cannot be obtained, and if it exceeds 1300, sufficient strength cannot be obtained,
The curability of the coating film surface is insufficient and an uncured feeling remains. The preferred number average molecular weight is from 350 to 950. The number average molecular weight can be measured by gel permeation chromatography and obtained using a standard polystyrene calibration curve.

In the present invention, as the glycol component, together with the component (b), as the glycol compound (c), (poly) ethylene or propylene glycol (c1) represented by the general formula (I) or the general formula (II)
The block type polyoxyethylene polyoxypropylene glycol type glycol (c2) represented by (Poly) ethylene or propylene glycol (c1) represented by the general formula (I) has a molecular weight of 62 or more;
The number average molecular weight is 700. Here, the number average molecular weight is 7
If it exceeds 00, sufficient coating surface curability and coating film strength cannot be obtained. Here, (c1) is a single compound when the molecular weight is low (that is, when a in the general formula (I) is about 1 to 3), and the molecular weight is constant with monodispersion. In this case, since the mixture is generally a mixture, it is appropriate to have a distribution in the molecular weight and to express the number average molecular weight. The number average molecular weight can be measured by gel permeation chromatography and obtained using a standard polystyrene calibration curve.

(C1) Preferably, monoethylene glycol, diethylene glycol, triethylene glycol, diethylene glycol having a number average molecular weight of 200 to 600, monopropylene glycol, dipropylene glycol, tripropylene glycol, and a number average molecular weight of 200 to 600 are preferable. Dipropylene glycol or the like is used.

In the present invention, the glycol compound (c2) represented by the general formula (II) has a (poly) oxyethylene repeating unit on both sides of a (poly) oxypropylene repeating unit, and a hydroxyl group on both sides thereof. This is a so-called block type glycol compound having a shape having The glycol compound (c2) preferably has a number average molecular weight of 300 to 1,000. If the molecular weight is less than 300, sufficient elongation of the coating film cannot be obtained,
If it exceeds 30, sufficient coating film surface curability and coating film strength cannot be obtained. The preferred number average molecular weight is from 500 to 1,000.

As the ethylenically unsaturated compound (d) having a hydroxyl group in the present invention, for example, 2-hydroxyethyl (meth) acrylate ((meth) acrylate represents acrylate or methacrylate).
The same applies hereinafter. ), 2-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate,
Hydroxyalkyl (meth) acrylates having an alkyl group having 2 to 7 carbon atoms, such as 4-hydroxybutyl (meth) acrylate, are preferred. In addition, polyethylene glycol mono (meth) acrylate and polypropylene glycol mono (meth) acrylate ) Acrylates, N-methylolacrylamide, N-methylolmethacrylamide, compounds having a hydroxyl group and an ethylenically unsaturated double bond obtained by ring-opening polymerization of an ε-caprolactone monomer, and the like. Among these compounds, 2-hydroxyethyl acrylate is most preferable because the obtained coating film surface has no uncured feeling and is extremely excellent in curability.

The ratio of each component in the reaction for obtaining the urethane compound (A) having an unsaturated double bond at both terminals was such that the number of moles of the hydroxyl group present in the hydroxyl group-containing unsaturated compound (e) was 2. Sometimes, the number of moles of the isocyanate compound (a) is 2 to 6, and the total number of hydroxyl groups present therein is 1 to 1.1 equivalents relative to 1 equivalent of the isocyanate group of the isocyanate compound (a). preferable. Here, when the amount of the isocyanate compound is less than 2, it is difficult to give sufficient elongation to the obtained resin composition, and when it is more than 6, good surface curability and sufficient strength are imparted to the obtained resin composition. Not only is it difficult to perform, but also it is difficult to obtain good handling due to an increase in resin viscosity.

The ratio of each component of the polyoxytetramethylene glycol compound (b), the glycol compound (c) and the ethylenically unsaturated compound (d) having a hydroxyl group is as follows: The total amount of the oxytetramethylene glycol compound (b) and the glycol compound (c) is preferably from 1 to 6.1 mol, and the polyoxytetramethylene glycol compound (b) and the glycol compound (c) have a molar ratio of 9 for the former / latter. / 1 to 4/6.

The urethane compound (A) having an unsaturated double bond at both terminals in the present invention can be obtained by mixing the above components and reacting the mixture at preferably 60 to 80 ° C. for 5 to 12 hours. . At that time, a reaction catalyst such as an organic solvent and dibutyltin dilaurate can be used if necessary. Examples of the organic solvent include ester-based, ketone-based, and aromatic organic solvents.Examples of the ester-based organic solvent include butyl acetate and butyl acetate. Is, for example, methyl ethyl ketone, and the aromatic organic solvent is, for example, toluene, xylene, or the like. When these organic solvents are used, they are used alone or in combination of two or more.

The photopolymerizable monomer (B) having one or more unsaturated photocurable double bonds per molecule in the present invention is a monofunctional monomer having a vinyl group, an acryloyl group, a methacryloyl group, or the like. Functional or polyfunctional photopolymerizable monomers can be used alone or in combination of two or more. Among these, a (meth) acrylate compound having an acryloyl group or a methacryloyl group is preferable,
For example, methyl (meth) acrylate, ethyl (meth)
Acrylate, n-propyl (meth) acrylate, n
-Butyl (meth) acrylate, tert-butyl (meth)
Acrylate, isobutyl (meth) acrylate, 2-
Alkyl (meth) acrylates such as ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, n-hexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, and tridecyl (meth) acrylate; ethoxyethyl (meth) Alkoxyalkyl (meth) acrylates such as acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, 2-methoxyethoxyethyl (meth) acrylate, and 2-ethoxyethoxyethyl (meth) acrylate; glycidyl (meth) acrylate; Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; A) fluorinated alkyl (meth) acrylates such as alkoxy (poly) alkylene glycol (meth) acrylates such as acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, and octafluoropentyl (meth) acrylate; Dialkylaminoalkyl (meth) acrylates such as N-dimethylaminoethyl (meth) acrylate and N, N-diethylaminoethyl (meth) acrylate, allyl (meth)
Acrylate, 1,3-butanediol (meth) acrylate, 1,4-butanediol (meth) acrylate, 1,6-hexanediol (meth) acrylate,
Glycol mono (meth) acrylates such as 3-methylpentanediol (meth) acrylate, monofunctional (meth) acrylate compounds such as (meth) acryloylmorpholine, polyethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate , Neopentyl glycol di (meth) acrylate,
Triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, hydroxypivalic acid ester neopentyl glycol di (meth) acrylate, trimethylolpropane di (meth)
Acrylate, 1,3-bis (hydroxyethyl)-
5,5-dimethylhydantoin di (meth) acrylate, α, ω-di (meth) acrylic bisdiethylene glycol phthalate, trimethylolpropane tri (meth)
Acrylate, pentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, 2-hydroxyethyl (meth)
Acryloyl phosphate, trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth)
Examples include polyfunctional (meth) acrylates such as acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and diacryloxyethyl phosphate. Also, α, ω
-Those having a vinyl group or the like such as tetraallylbistrimethylolpropane tetrahydrophthalate, N-vinylpyrrolidone, and N-vinylcaprolactam can also be used. Of these, (meth) acrylate compounds are preferred.

The component (B) is preferably used in an amount of 1 to 50% by weight, more preferably 5 to 25% by weight, based on the total amount of the component (A). This amount is 1
If the amount is less than 50% by weight, the curability is not sufficient. If the amount is more than 50% by weight, properties such as surface curability, elongation, strength and the like of the obtained coating film tend to be generally deteriorated. It is preferable that the component (B) is blended in that the handleability is improved by lowering the viscosity. Examples of the photopolymerization initiator (C) in the present invention include a carbonyl-based photopolymerization initiator, a sulfide-based photopolymerization initiator, a quinone-based photopolymerization initiator, an azo-based photopolymerization initiator, a sulfochloride-based polymerization initiator, Thioxanthone-based photopolymerization initiators, peroxide-based photopolymerization initiators, isoamyl o-dimethylaminobenzoate and the like can be mentioned.

Examples of the carbonyl-based photopolymerization initiator include benzophenone, diacetyl, benzyl, benzoin, ω-bromoacetophenone, chloroacetone, acetophenone, 2,2-diethoxyacetophenone,
2,2-dimethoxy-2-phenylacetophenone, p
-Dimethylaminoacetophenone, p-dimethylaminopropiophenone, 2-chlorobenzophenone, 4,
4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone, Michler's ketone, benzoin methyl ether, benzoin isobutyl ether, benzoin-n-butyl ether, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2
-Hydroxy-2-methyl-1-phenylpropane-1
-One, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, methylbenzoyl formate, 2,2-diethoxyacetophenone,
4-N, N'-dimethylacetophenone and the like.

Examples of the sulfide-based photopolymerization initiator include diphenyl disulfide, dibenzyl disulfide, tetraethylthiuram disulfide, tetramethylammonium monosulfide and the like. Examples of the quinone-based photopolymerization initiator include benzoquinone and anthraquinone. Examples of the azo-based photopolymerization initiator include azobisisobutyronitrile, 2,2-azobispropane, hydrazine and the like. Examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, and the like. Examples of the peroxide-based photopolymerization initiator include benzoyl peroxide, di-tert-butyl peroxide and the like. These photopolymerization initiators are used alone or in combination of two or more.

The proportion of the component (C) is determined by considering the balance between the photocurability and the properties of the resulting cured product (curability, flexibility (elongation), etc.). The amount is preferably 1 to 10% by weight, more preferably 3 to 5% by weight based on the amount. 1% by weight
If it is less than 1, the photocuring tends to be insufficient, and
When the amount is more than 10% by weight, the properties (curability, flexibility (elongation), etc.) of the obtained cured product tend to be generally reduced.

The photocurable resin composition of the present invention can be used for a paint. In that case, if necessary, a natural or synthetic polymer substance, a filler, an extender pigment, a pigment, a polymerization inhibitor, a leveling agent, a modifier, a plasticizer, etc. are added to the photocurable resin composition of the present invention. can do.

Examples of the natural polymer include oils and fats, and examples of the oils and fats include linseed oil, tung oil, soybean oil, castor oil, and epoxidized oil. For example, unsaturated polyester resins, vinyl ester resins, vinyl urethane resins, vinyl ester urethane resins, polyisocyanates, polyepoxides, epoxy-terminated polyoxazolidones, acrylic resins, alkyd resins, urea resins, melamine resins,
Examples thereof include polydiene elastomers, saturated polyesters, saturated polyethers, and cellulose derivatives. As the cellulose derivative, for example, nitrocellulose,
Cellulose acetate butyrate and the like can be mentioned.

Examples of the filler and extender include calcium carbonate, talc, mica, clay, silica powder, colloidal silica, barium sulfate, aluminum hydroxide, zinc stearate and the like. Examples of the pigment include zinc white, red iron, azo pigment and the like.

Examples of the polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, benzoquinone, p-tert-butyl carbitol, 2,6-di-tert.
-Butyl-4-methylphenol and the like. Examples of the leveling agent include a polyether-modified dimethylpolysiloxane copolymer, a polyester-modified dimethylpolysiloxane copolymer, a polyether-modified methylalkylpolysiloxane copolymer, and an aralkyl-modified methylalkylpolysiloxane copolymer. .

Examples of the plasticizer include dihydric alcohol ester plasticizers, other ester plasticizers, epoxy plasticizers, polyester plasticizers, and the like. Examples of the dihydric alcohol ester plasticizer include: , Diethylene glycol dibenzoate, triethylene glycol-di-2-ethyl butyrate, and the like. Examples of other ester plasticizers include, for example, tributyl phosphate, triphenyl phosphate, tri-2-ethylhexyl phosphate, adipine Dibutyl acid, di-n-hexyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate, dioctyl sebacate, diethyl phthalate,
Examples thereof include dibutyl phthalate, di-n-octyl phthalate, and butyl oleate.

The photocurable resin composition of the present invention has a low viscosity and can be used as a solventless paint.
Organic solvents can also be used. Examples of the organic solvent include those exemplified as the organic solvent used to obtain the component (A). The mixing ratio of the natural or synthetic polymer substance, filler, extender pigment, pigment, polymerization inhibitor, leveling agent, modifier, plasticizer and organic solvent is appropriately selected depending on the use of the obtained paint, and is particularly limited. However, when these are blended, the total amount of each component is from 0.01% by weight to 50% by weight based on the weight of the paint.
It is preferable to set the weight%.

As a method of forming a coating, for example, known methods such as a paint shaker method, a roll mill method, a sand mill method, a disperser method, a kneader method, and a high-speed impeller mill method can be used. The paint of the present invention can be applied for painting according to a usual painting method. For coating, for example, an air spray method, an airless sprayer, an electrostatic coater, a dipping, a roll coater, a brush, or the like can be used.

The paint of the present invention has excellent curing properties,
It can be used for painting metal materials such as iron and aluminum, calcium silicate board, pulp cement board, lightweight concrete board, asbestos cement board, inorganic building materials such as mortar, wood, paper, plastic base materials, etc. The coating film can be cured by irradiating the coating film with ultraviolet rays using a metal halide lamp or the like as a light source.

[0030]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the following, "parts" and "%"
All are by weight unless otherwise noted.

Production Example 1 (Urethane acrylate compound
1) After introducing air gas into a reaction vessel equipped with a stirrer, thermometer, cooling pipe, and air gas introduction pipe, 232 parts of 2-hydroxyethyl acrylate (2-HEA), polyoxytetramethylene glycol (Hodogaya) Chemical Industry Co., Ltd., P
434 parts of TG850SN, number average molecular weight 868), polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., PEG40)
0, 220 parts of a number average molecular weight of about 400), 0.7 parts of hydroquinone monomethyl ether, and 0.7 parts of dibutyltin dilaurate (L101, manufactured by Tokyo Fine Chemical Co., Ltd.), heated to 70 ° C, and then kept at 70 to 75 ° C. And isophorone diisocyanate (VELS, VELS)
444 parts of (STANAT IPDI) was uniformly added dropwise over 3 hours to carry out a reaction. When the reaction was allowed to proceed for about 5 hours after the completion of the dropwise addition, IR measurement confirmed that the isocyanate had disappeared, and the reaction was terminated. Thus, a urethane acrylate compound having a solid content of about 100% was obtained.

Production Example 2 (Urethane acrylate compound
2) After introducing air gas into a reaction vessel equipped with a stirrer, thermometer, cooling pipe and air gas introduction pipe, 232 parts of 2-hydroxyethyl acrylate (2-HEA) and polyoxytetramethylene glycol (Hodogaya) Chemical Industry Co., Ltd., P
434 parts of TG850SN, number average molecular weight 868), polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., PEG40)
0, 220 parts of a number average molecular weight of about 400), 0.7 parts of hydroquinone monomethyl ether, and 0.7 parts of dibutyltin dilaurate (L101, manufactured by Tokyo Fine Chemical Co., Ltd.), heated to 70 ° C, and then kept at 70 to 75 ° C. And isophorone diisocyanate (VELS, VELS)
(STANAT IPDI) 295 parts, Tolylene diisocyanate (Nippon Polyurethane Co., Ltd., Coronate T-8)
0) 117 parts of the mixed liquid was uniformly dropped over 3 hours to carry out a reaction. When the reaction was allowed to proceed for about 5 hours after the completion of the dropwise addition, IR measurement confirmed that the isocyanate had disappeared, and the reaction was terminated. Thus, a urethane acrylate compound having a solid content of about 100% was obtained.

Production Example 3 (Urethane acrylate compound
3) After introducing air gas into a reaction vessel equipped with a stirrer, thermometer, cooling pipe and air gas introduction pipe, 232 parts of 2-hydroxyethyl acrylate (2-HEA) and polyoxytetramethylene glycol (Hodogaya) Chemical Industry Co., Ltd., P
TG850SN, 434 parts of number average molecular weight 868), a polyoxyethylene polypropylene alkyl ether type glycol compound (manufactured by Toho Chemical Industry Co., Ltd., Pepol B-0)
44, a number average molecular weight of about 610, c in the general formula (II)
Is about 7, b + d is about 2) 335 parts, hydroquinone monomethyl ether 0.7 parts and dibutyl tin dilaurate (L101, manufactured by Tokyo Fine Chemical Co., Ltd.) 0.7 parts are charged, and the temperature is raised to 70 ° C. and then 70 to 75 ° C. Keep warm, isophorone diisocyanate (VES, manufactured by Huls Japan)
295 parts, tolylene diisocyanate (Coronate T-80, manufactured by Nippon Polyurethane Co., Ltd.)
117 parts of the mixed liquid was uniformly dropped in 3 hours to carry out a reaction. When the reaction was allowed to proceed for about 5 hours after the completion of the dropwise addition, IR measurement confirmed that the isocyanate had disappeared, and the reaction was terminated. Thus, a urethane acrylate compound having a solid content of about 100% was obtained.

Production Example 4 (Urethane acrylate compound
4) After introducing air gas into a reaction vessel equipped with a stirrer, thermometer, cooling pipe and air gas introduction pipe, 232 parts of 2-hydroxyethyl acrylate (2-HEA), polyoxytetramethylene glycol (BASF Acti 263 parts of Poly THF 250, a number average molecular weight of about 250) manufactured by Engezel Shaft, 0.5 part of hydroquinone monomethyl ether and 0.5 part of dibutyltin dilaurate (L101 manufactured by Tokyo Fine Chemical Co., Ltd.) are charged, and the temperature is increased to 70 ° C. After keeping the temperature at 75 ° C., isophorone diisocyanate (VESTANAT IP manufactured by Huls Japan)
DI) 444 parts were added dropwise over 3 hours to carry out a reaction. When the reaction was allowed to proceed for about 5 hours after the completion of the dropwise addition, IR measurement confirmed that the isocyanate had disappeared, and the reaction was terminated. Thus, a urethane acrylate compound having a solid content of about 100% was obtained.

Production Example 5 (Urethane acrylate compound
5) After introducing air gas into a reaction vessel equipped with a stirrer, thermometer, cooling pipe, and air gas introduction pipe, 232 parts of 2-hydroxyethyl acrylate (2-HEA), polyoxytetramethylene glycol (Hodogaya) Chemical Industry Co., Ltd., P
TG2000SN, number average molecular weight about 2030) 2132
Parts, 1.4 parts of hydroquinone monomethyl ether and dibutyltin dilaurate (manufactured by Tokyo Fine Chemical Co., Ltd.
L101) After adding 1.4 parts and raising the temperature to 70 ° C., 70 to 75
C., and 444 parts of isophorone diisocyanate (VESTANAT IPDI, manufactured by Huls Japan) were uniformly dropped over 3 hours to carry out a reaction. When the reaction was allowed to proceed for about 5 hours after the completion of the dropwise addition, it was confirmed by IR measurement that the isocyanate had disappeared, the reaction was terminated, and the solid content was about 100%.
Was obtained.

Table 1 shows the number of moles mixed in Production Examples 1 to 5.

[Table 1]

Examples 1 to 3 The urethane acrylate compounds obtained in Production Examples 1, 2 and 3 were used as photopolymerizable monomers having one or more unsaturated photocurable double bonds in one molecule. Polyethylene glycol diacrylate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., PE30
Benzyldimethylketal (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., BD)
The photocurable resin composition was prepared by blending 3% by weight of K) with respect to the total amount of the urethane acrylate compound and the photopolymerizable monomer and mixing them uniformly.

Example 4 The urethane acrylate compound obtained in Production Example 2 was modified with a polyethylene glycol diacrylate (No. 1) as a photopolymerizable monomer having one or more photocurable unsaturated double bonds in one molecule. A mixture of 10% by weight of PE300 manufactured by Ichi Kogyo Seiyaku Co., Ltd.) and benzyldimethyl ketal (BDK manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a photopolymerization initiator, a urethane acrylate compound and a photopolymerizable monomer The photocurable resin composition was prepared by blending 3 wt% with respect to the total amount of the above and mixing uniformly.

COMPARATIVE EXAMPLES 1-2 The urethane acrylate compounds obtained in Production Examples 4 and 5 were prepared using polyethylene glycol as a photopolymerizable monomer having one or more photocurable unsaturated double bonds in one molecule. A mixture of diacrylate (PE300, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., PE300) at 20% by weight, benzyldimethyl ketal (BDK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a photopolymerization initiator, a urethane acrylate compound and photopolymerization. The photocurable resin composition was prepared by blending 3% by weight with respect to the total amount of the reactive monomer and uniformly mixing.

Evaluation Evaluation of surface curability: The photocurable resin compositions obtained from the above Examples and Comparative Examples were cured on a glass plate to a thickness of 10 μm.
m using a bar coater, and using an ultraviolet irradiation device (6 kW, 80 W / cm high-pressure mercury lamp, 2 UV irradiation devices; manufactured by Nippon Battery Co., Ltd.), one 80 W / cm high-pressure mercury lamp,
Each time the film was irradiated and cured at an irradiation distance of 15 cm and a conveyor speed of 20 m / min (a single irradiation amount of about 150 mJ / cm ² ), the coating film surface was touched with a finger to evaluate the degree of curing of the coating film surface. ○: Completely cured, Δ: Slightly uncured, ×: Uncured

Measurement of elongation and tensile strength of cured coating film:
After applying the photocurable resin composition obtained from the above Examples and Comparative Examples on a glass plate using an applicator so that the thickness of the cured coating film becomes 50 μm, the above UV irradiation device was used to apply a 80 W / cm high pressure mercury lamp. One lamp, an irradiation distance of 15 cm and a conveyor speed of 5 m / min (a single irradiation amount of about 500 mJ / cm ² ) were used and completely cured by irradiation. The evaluation was performed by cutting the cured film into strips having a length of 50 mm and a width of 15 mm at an environmental temperature of 20 ° C., adjusting the test span to 25 mm, and pulling at a speed of 10 mm.
The film was stretched at a rate of / min until the cured film was broken, and the calculated elongation (%) and tensile strength were determined from the elongation (mm) and the strength (kgf) at break from the following formula.

[0042]

(Equation 1)

Evaluation of the degree of yellowing over time of the cured coating film: A steel plate (150 mm × 70 mm × 2 mm, manufactured by Nippon Test Panel Co., Ltd.), which was subjected to white baking, was obtained from the above Examples and Comparative Examples. The cured photo-curable resin composition has a cured coating thickness of 10 μm.
After applying using a bar coater, one ultraviolet high pressure mercury lamp was used with the ultraviolet irradiation device, and the irradiation distance was 15
cm, Conveyor speed 5m / min (irradiation amount per time about 500mJ / c
m ² ). The evaluation was performed on the coating film after curing with ultraviolet irradiation and the coating film after 48 hours with a sunshine weatherometer (WEL-SUN-HC, manufactured by Suga Test Instruments Co., Ltd.) using a color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd.). , SZ-
From the XYZ tristimulus values measured in # 80), a color difference (ΔE) was obtained by a Hunter color difference formula, and the yellowing degree with time was evaluated. Note that ΔE of 3 or less was regarded as good.

[0044]

(Equation 2)

Table 2 shows the results.

[0046]

[Table 2]

The photocurable resin compositions obtained in Examples 1 to 4 were prepared under the conditions of one 80 W / cm high-pressure mercury lamp, irradiation distance of 15 cm, and conveyor speed of 20 m / min (a single irradiation amount of about 150 mJ / cm ² ). Irradiation twice under the conditions (ultraviolet irradiation amount about 300 mJ / cm ² )
, And has a flexibility of elongation of 50% or more. In addition, the degree of yellowing over time was all 3 or less, indicating good coating film properties. The photocurable resin composition obtained in Comparative Example 1 had the surface curability and the degree of yellowing over time of the cured coating film obtained in Example 1.
~ 4, but the coating film had an elongation of 10% or less and was very poor in flexibility. Further, the photocurable resin composition obtained in Comparative Example 2 has excellent flexibility of the cured coating film, and the tensile strength and the degree of yellowing with the lapse of time are almost the same as those of the Example, but the surface curability is significantly poor. Had become a membrane.

[0048]

The photocurable resin composition according to any one of claims 1 to 4 improves the surface curability of a coating film while maintaining good elongation and breaking strength, that is, flexibility, and provides a cured coating film. It has little yellowing with time, has low viscosity and can be applied as a solventless type, and can be provided with an inexpensive material. The paint according to claim 5 has good elongation and breaking strength,
In other words, the surface curability of the coating film is improved while maintaining the flexibility, the yellowing of the coating film after curing is reduced with time, and it can be applied as a solventless type with a low viscosity. Can be provided.

Claims (6)

[Claims] 1. An isocyanate compound (a) having two isocyanate groups in one molecule, having a number average molecular weight of 300 to
1300 polyoxytetramethylene glycol compound (b), general formula (I) (Where a is an integer of 1 or more, R is a hydrogen atom or a methyl group, and has a molecular weight of 62 or more and a number average molecular weight of 700 or less) or a general formula (II) ] (Where b, c, and d are integers of 1 or more and the number average molecular weight is 300 to 1000), and the ethylenically unsaturated compound (d) having a hydroxyl group is reacted with the glycol compound (c). Urethane compound having unsaturated double bonds at both ends (A), photopolymerizable monomer (B) having one or more photocurable unsaturated double bonds in one molecule, and photopolymerization A photocurable resin composition containing an initiator (C). 2. The ratio of each component in the reaction for obtaining a urethane compound (A) having an unsaturated double bond at both terminals is such that the number of moles of hydroxyl groups present in the hydroxyl group-containing unsaturated compound (e) is 2 And the number of moles of the isocyanate compound (a) is 2 to 6, and the polyoxytetramethylene glycol compound (b), the glycol compound (c) and the hydroxyl group are equivalent to one equivalent of the isocyanate group of the isocyanate compound (a). The photocurable resin composition according to claim 1, wherein the total of the hydroxyl groups present in the group-containing ethylenically unsaturated compound (d) is 1 to 1.1 equivalent. 3. The isocyanate compound (a) is one or more compounds (a1) selected from isophorone diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, trimethyl hexamethylene diisocyanate, and tetramethyl xylylene diisocyanate. Or the molar ratio of (a1) and tolylene diisocyanate (a2) is (a2) / (a
The photocurable resin composition according to claim 1 or 2, wherein 1) satisfies ≤ 2.5. 4. The urethane compound (A) having an unsaturated double bond at both terminals has a number average molecular weight of 1,000 to 4,000.
The photocurable resin composition according to claim 1, 2, or 3. 5. The weight ratio of the urethane compound (A) having an unsaturated double bond at both terminals to the photopolymerizable monomer (B) is as follows:
(A) / (C) is 25/75 to 5/95, and the photopolymerization initiator (C) is 1 to 10% by weight based on the total amount of the components (A) and (B). The photocurable resin composition according to any one of items 1 to 4. 6. A paint containing the photocurable resin composition according to claim 1.