JPH0730159B2 - Method for producing radiation curable resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Field of Industrial Application) The present invention is applied to paints, adhesives, printing inks, photosensitive resin plates, etc., and is radiation cured having an ethylenically unsaturated double bond. The present invention relates to a method for producing a resin.

(Prior Art) Radiation-curable resins such as paints, adhesives, printing inks, photosensitive resin plates, and photoresists for metals and plastics have been widely used. Especially in the fields of paints, adhesives, printing inks, etc., in addition to adhesion to substrates, processing adhesion, heat resistance, weather resistance, chemical resistance, water resistance, etc., high speed paintability, high speed drying, etc. High-speed workability and reduction of curing energy are required. In order to satisfy these requirements, it is necessary to improve the curability. For this reason, the radiation-curable resin is often combined with many monomers having two or more ethylenically unsaturated double bonds. There are methods such as using a radiation curable resin having a high bond density.

The cured coating film obtained by the above-mentioned method is generally brittle, and has poor adhesion to a substrate and processing adhesion, and insufficient resistance.

Further, as the radiation curable resin, a resin obtained by reacting a resin having two or more hydroxyl groups with an isocyanate compound having an ethylenically unsaturated double bond is preferably used. As the isocyanate compound having an ethylenically unsaturated double bond, an adduct obtained by reacting a monohydroxy compound having an ethylenically unsaturated double bond with diisocyanate, or isocyanate ethyl methacrylate or methacryloyl isocyanate is used. When an attempt is made to introduce an ethylenically unsaturated double bond into such a radiation-curable resin at a high density, when the above-mentioned adduct is used, a cross-linking reaction occurs due to the unreacted diisocyanate present therein, resulting in a high viscosity or When a problem such as gelation occurs and isocyanate ethyl methacrylate or methacryloyl isocyanate is used, there is no problem such as gelation or viscosity increase, but the reaction to obtain isocyanate ethyl methacrylate or methacryloyl isocyanate has a complicated process, It was difficult to efficiently obtain a highly pure product.

(Problems to be Solved by the Invention) The present invention improves the above-mentioned various defects and has high curability,
A radiation-curable resin that has excellent adhesion to substrates, processing adhesion, chemical resistance, water resistance, high-speed paintability, high-speed workability such as high-speed drying, and reduced curing energy can be easily and easily A method of manufacturing at low cost is provided.

[Structure of Invention]

(Means for Solving Problems) In the present invention, a monohydroxy compound (A) having an ethylenically unsaturated double bond and a diisocyanate compound (B) are added to 0.5 mol of (B) per 1 mol of (A). The first step of obtaining a mixture (D) consisting of an adduct body mixture (C) of (A) and (B) and unreacted (B), (D), In a solvent that dissolves (C) and does not substantially dissolve (C) to substantially remove unreacted (B) to obtain (C), and a compound (E) having three or more hydroxyl groups. The method for producing a radiation-curable resin is characterized by comprising the third step of reacting (C) with (3). In the present invention, as the monohydroxy compound (A) having an ethylenically unsaturated double bond, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glycerol dimethacrylate, glycerol methacrylate acrylate, glycerol (meth) Acrylate monoarylate, butyl glycidyl ether (meth) acrylate, phenyl glycidyl ether (meth) acrylate, glycerol (meth) acrylate alkylate, glycerol (meth) acrylate alkenylate, polyethylene glycol mono (meth) acrylate, polyethylene glycol polypropylene glycol mono (Meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol polyteto Ramethylene glycol mono (meth) acrylate, polycapronate (meth) acrylate, cyclohexadiene monooxide (meth) acrylate, 4-vinyl-2-hydroxy-cyclohexyl-2 propenoate, 5-vinyl-2-hydroxy-cyclohexyl-2 -In addition to propenoate, allyl alcohol, etc., ester compounds obtained by reacting these with dicarboxylic acid anhydrides and glycidyl compounds, acryloxypropionic acid with ethylene oxide,
Examples thereof include those to which alkylene oxide such as propylene oxide is added, and Michael type addition products of 2-hydroxyethyl acrylate and / or 2-hydroxypropyl acrylate. In the present invention, a conventionally known compound can be used as the diisocyanate compound (B), and examples of such a diisocyanate compound include 2,4-toluene diisocyanate,
2,6-toluene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate , Dimeryl diisocyanate, lysine diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated toluene diisocyanate and the like.

The above (A) and (B) are (B) with respect to 1 mol of (A).
By reacting at a ratio exceeding 0.5 mol, a mixture (D) consisting of the adduct body mixture (C) of (A) and (B) and unreacted (B) is obtained. Reaction temperature is usually room temperature to 150
℃, preferably 40 to 100 ℃. If the temperature is lower than room temperature, the reaction tends to be slow, and if the temperature is higher than 150 ° C, a double bond polymerization reaction occurs together with the urethanization reaction, and gelation tends to occur easily. Further, in order to minimize the formation of an adduct body in which 2 mol of (A) is added to 1 mol of (B) and the remaining unreacted (B), it is preferable to use ( A) is reacted in a proportion of 0.8 to 1.2 mol, particularly preferably 0.9 to 1.1 mol of (A) per 1 mol of (B).

In the present invention, the solvent that dissolves (B) and does not substantially dissolve (C) is not particularly limited, and for example, a hydrocarbon solvent containing an aliphatic hydrocarbon and / or an alicyclic hydrocarbon as a main component is used. To be Such aliphatic hydrocarbons include n-pentane, n-hexane, 2-methylpentane, 2,2
-Dimethylbutane, 2,3-dimethylbutane, n-heptane, n
-Octane, 2,2,3-trimethylpentane, isooctane, n-nonane, 2,2,5-trimethylhexane, petroleum ether, petroleum benzine, ligroin, etc. Mention may be made of pentane, cyclohexane, methylcyclohexane, ethylcyclohexane, p-menthane and the like. Then, of these solvents, in order to improve the separation of the solvent after cleaning and the adduct body mixture (C), the ratio of reacting with the types of (A) and (B), that is, the adduct body mixture (C) Considering the difference between the specific gravity of) and that of the solvent,
It is preferable to appropriately select the solvent used for washing. In addition, the solvent after adsorbent mixture (C) after washing is not hindered and the solubility of the solvent in (B) and (C) is not significantly affected. Aromatic hydrocarbons, 2-butanone, 4-
Ketones such as methyl-2-pentanone and cyclohexanone, halogenated hydrocarbons such as dichloromethane and chloroform, ethers such as tetrahydrofuran and dioxane, esters such as ethyl acetate and n-propyl acetate, and the like can be added.

For cleaning, use a homomixer, dissolver, homogenizer,
After thoroughly mixing the solvent (D) with a stirrer such as a paddle mixer, planetary mixer or colloidal mill, the unreacted (B) after washing by means such as standing or centrifugation. It is carried out by separating the solvent containing (C) and (C).

The washing is usually performed at room temperature, but when the viscosity of (D) is high, the washing can be performed by heating. When heating is performed, a polymerization inhibitor may be added to the solvent for (D) and / or cleaning. The washing can be performed not only once but also a plurality of times, and the amount of the solvent used for the washing varies depending on the type of solvent, the mixed state of the solvent and (D), and the number of times of washing. 1-3 of (D)
Double amount (weight ratio) is efficient. The amount of unreacted (B) contained in (D) after washing can be quantified by means such as gel permeation chromatography (GPC). After cleaning, depending on the purpose and application (D)
If the amount of unreacted (B) contained in is less than 2 to 3% by weight, there is often no practical problem.

In the present invention, the compound (E) having three or more hydroxyl groups includes polyhydric alcohols such as glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol and sorbitol, and alkylenes such as ethylene oxide and propylene oxide. Oxides, tetrahydrofuran, ε-caprolactone, etc. added, these polyhydric alcohols or polyfunctional tribasic acids such as trimellitic acid and pyromellitic acid as essential components, and phthalic acid, isophthalic acid, terephthalic acid, A polyester resin with a terminal hydroxyl group obtained by reacting a dibasic acid such as adipic acid or succinic acid with a glycol such as ethylene glycol, 1,4-butazinol or neopentyl glycol, one of the hydroxyl groups of glycerin is a fatty acid, Alkyd resins esterified with natural resins, fibrin derivatives such as nitrocellulose, acetylcellulose, ethylcellulose and ethylhydroxyethylcellulose, copolymers containing hydroxyl group-containing (meth) acrylic acid ester as a copolymerization component, polyacetic acid Partially saponified vinyl, partially saponified vinyl chloride-vinyl acetate copolymer and other vinyl acetate as a copolymerization component, phenoxy resin, polyvinyl acetal resins such as polyvinyl butyral and polyvinyl formal, Examples include methylolated phenolic resins.

To reduce the residual isocyanate groups in the resulting radiation-curable resin and suppress changes in physical properties after curing,
It is preferable to react (E) and (C) at a ratio of isocyanate group / hydroxyl group (molar ratio) of less than 1.05. In addition, when (E) has a high molecular weight and the number of hydroxyl groups in one molecule of (E) is extremely large, for example, (E) is a partial saponification product of polyvinyl acetate or a partial saponification product of vinyl chloride-vinyl acetate copolymer. In the case of a partially saponified product of a copolymer containing vinyl acetate as a copolymerization component or a fibrin derivative,
It is preferable to react 3 to 25 mol of the compound having an isocyanate group in (C) with 1 mol of (E). In such a case, if the ratio of the compound having an isocyanate group in (C) reacted with 1 mol of (E) is less than 3 mol, the curability of the resulting radiation curable resin tends to be slightly lower. However, if the amount exceeds 25 mol, the radiation-cured resin after curing tends to be slightly brittle, and the adhesion with metals tends to be slightly lower. (E) and (C)
The reaction with is carried out at room temperature to 150 ° C, preferably 40 to 100 ° C, and when (E) and (C) are reacted at a ratio of isocyanate group / hydroxyl group (molar ratio) of less than 1.05,
The reaction between (E) and (C) is the infrared absorption spectrum (IR
Spectrum) characteristic absorption of isocyanate groups (2275c
It continues until m ^-1 ) disappears.

If the reaction temperature is lower than room temperature, the reaction will slow down to 150 ° C.
If it is higher, polymerization of the ethylenically unsaturated double bond occurs together with the urethanization reaction, and gelation tends to occur easily.
In the reaction, a conventionally known urethanization catalyst, for example,
Sodium hydroxide, potassium hydroxide, lithium chloride, tin octylate, dibutyltin dilaurate, diethylzinc tetra (n-butoxy) titanium, triethylamine, N, N-dimethylbenzylamine, etc., and ethylenically unsaturated double bond A polymerization inhibitor such as hydroquinone or monomethoxyhydroquinone can be added and used in order to suppress the polymerization and prevent gelation. The reaction may be carried out in the presence of various organic solvents which are not involved in the reaction or oligomers or monomers having an ethylenically unsaturated double bond.

The radiation-curable resin obtained by the present invention contains various organic solvents, styrene, (meth) acrylic acid, (meth) acrylic acid alkyl ester, (meth) acrylic acid amide, (meth) acrylic, if necessary. Glycidyl acid salt, polyethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, polyurethane (meth) acrylate, etc. Monomers and oligomers with double bonds, thermoplastic resins, titanium white, zinc white, carbon black, carmine 6B, anthraquinone violet, phthalocyanine blue, phthalocyanine green, dyes and pigments such as aluminum flakes, carbonic acid Calcium, magnesium carbonate,
Kaolin, talc, clay mica, chlorite, filler such as white carbon, iron oxide-based, chromium oxide-based, iron powder-based magnetic powder, glass fiber, asbestos, synthetic fiber, metal fiber, carbon fiber, titanic acid Reinforcing agents such as alkali low-order oxide fibers, foaming agents such as ammonium carbonate, dinitrosopentamethylenetetramine, and sulfohydrazide, and foaming aids such as urea-based, organic acid-based, metal salt-based, anion activator, cationic activity Agents, antistatic agents consisting of nonionic or amphoteric active agents, UV absorbers such as benzophenone-based, benzotriazole-based, salicylate-based, antioxidants, lubricants such as n-butyl oleate and stearic acid, phosphorus-based, Halogen-based and metal hydroxide-based flame retardants, nickel powder, silver powder, copper powder, iron powder, aluminum powder, and other metal powders Carbon black, graphite,
A conductive agent such as metal oxide powder, carbon fiber, metal fiber, and various fragrances can be added and used.

The radiation curable resin obtained by the present invention can be cured by radiation such as ultraviolet rays and electron beams. When it is cured by ultraviolet rays, in order to enhance the curability,
It is preferable to add a photopolymerization initiator and, if necessary, a photopolymerization accelerator to the radiation curable resin obtained by the present invention. Examples of such a photopolymerization initiator include benzophenone, methylbenzophenone, o-benzoylbenzoic acid, benzoylethyl ether, and 2,2-diethoxyacetophenone. As a photopolymerization accelerator, 4,4-bis (diethylamino) is used. ) Benzophenone, dimethylethanolamine, etc.

(Examples) Hereinafter, the present invention will be described with reference to Examples. In the examples, "part" means "part by weight" and "%" means "% by weight".

Example 1 222 parts of isophorone diisocyanate kept at 80 ° C.
130 parts of hydroxypropyl acrylate and 0.13 parts of hydroquinone were added dropwise over 2 hours and then reacted at 80 ° C. for 3 hours to obtain a reaction product (a). The amount of unreacted isophorone diisocyanate contained in the reaction product (a) was about 6%.

To 200 parts of the obtained reaction product (a), 300 parts of n-hexane was added, and the mixture was stirred at high speed for 30 minutes and allowed to stand, whereby two layers were separated. Excluding the upper layer, 300 parts of n-hexane was added to the lower layer,
The mixture was stirred again at high speed for 30 minutes and then left standing to obtain an adduct body mixture (b) in the lower layer of the separated two layers. The amount of unreacted isophorone diisocyanate contained in the adduct mixture (b) was less than 1%.

230 parts of vinyl chloride-vinyl acetate copolymer partially saponified product "Vinylite VAGH" (trade name, manufactured by Union Carbide Co., Ltd.) is dissolved in 245 parts of toluene and 245 parts of 2-butanone by heating at 80 ° C, and an adduct mixture is added thereto. (B) 52.8 parts, hydroquinone 0.05 parts, tin octylate 1.3 parts, toluene 62
And 62 parts of 2-butanone were added dropwise over 30 minutes, and the reaction was continued at 80 ° C until the characteristic absorption of the isocyanate group disappeared in the IR spectrum.
An organic solvent solution of a resin having 15 ethylenically unsaturated double bonds was obtained.

2-butanone was added to the obtained resin solution to obtain a solid content of 25
%, And then benzoin ethyl ether was added so that the content was 2% with respect to the total amount of the coating material to obtain a coating material. The obtained coating material was applied on an aluminum plate to a dry-cured coating thickness of 20 μm, and the organic solvent was volatilized, followed by two 80 W ultraviolet lamps 10 cm below, line speed 1 m /
The coating was cured by irradiating it with ultraviolet rays for a minute. The performance evaluation results of the obtained cured coating film are shown in Table 1.

Comparative Example 1 A reaction with "Vinylite VAGH" was carried out in the same manner as in Example 1 except that the reaction product (a) was used in place of the adduct mixture (b), and gelled at a reaction rate of 41%. I got it.

EXAMPLE 2 2-Hydroxy was prepared in the same manner as in Example 1 except that 222 parts of isophorone diisocyanate were replaced by 174 parts of a toluene diisocyanate mixture consisting of 80% 2,4-toluene diisocyanate and 20% 2,6-toluene diisocyanate. Reaction with propyl acrylate was performed to obtain a reaction product (c). The amount of unreacted toluene diisocyanate contained in the reaction product (c) was about 4%.

When 608 parts of cyclohexane was added to 304 parts of the obtained reaction product (c), and the mixture was stirred at high speed for 30 minutes and then allowed to stand, it was separated into two layers. The amount of unreacted toluene diisocyanate contained in the lower layer adduct mixture (d) was less than 1%.

The reaction with "Vinylite VAGH" was carried out in the same manner as in Example 1 except that 60.8 parts of the adduct body mixture (d) was used instead of 52.8 parts of the adduct body mixture (b).
A solution of a resin having 20 ethylenically unsaturated double bonds in an organic solvent was obtained.

2-butanone was added to the obtained resin solution to give a solid content of 25%.
The paint was obtained. The obtained coating material was applied onto an aluminum plate so as to have a dry-cured coating film thickness of 50 μm, the organic solvent was volatilized, and then the coating film was cured by irradiating an electron beam with an acceleration voltage of 160 kV and 3 Mrad. The performance evaluation results of the obtained cured coating film are shown in Table 1.

Comparative Example 2 A reaction with "Vinylite VAGH" was carried out in the same manner as in Example 2 except that the reaction product (c) was used instead of the adduct mixture (d), and it gelled at a reaction rate of 51%. Oops.

Example 3 The reaction with "Vinylite VAGH" was carried out in the same manner as in Example 2 except that the amount of the adduct mixture (d) was changed to 80.2 parts, and an average of about 27 ethylenically unsaturated double bonds in one molecule. An organic solvent solution of a resin having Table 1 shows the performance evaluation results of the cured coating films obtained from the obtained resin solution in the same manner as in Example 2.

Example 4 1,6-hexamethylene diisocyanate 168 kept at 80 ° C
146 parts of polyethylene glycol (degree of polymerization: 2) monomethacrylate and 0.15 part of hydroquinone were added dropwise to 2 parts over 2 hours, and the reaction was carried out at 80 ° C. for 5 hours to obtain a reaction product (e). Unreacted 1, contained in the reaction product (e)
The amount of 6-hexamethylene diisocyanate was about 4%.

When 597 parts of n-heptane and 31 parts of toluene were added to 314 parts of the obtained reaction product (e), and the mixture was stirred at high speed for 30 minutes and allowed to stand, two layers were separated. The amount of unreacted 1,6-hexamethylene diisocyanate contained in the lower layer adduct mixture (f) was less than 1%.

230 parts of "Vinylite VAGH" was dissolved in 245 parts of toluene and 245 parts of 2-butanone by heating at 80 ° C, and 31.4 parts of adduct mixture (f), 0.03 part of hydroquinone, 0.6 part of dibutyltin dilaurate, 37 parts of toluene. And 2-butanone (37 parts) were added dropwise over 30 minutes, and the reaction was continued at 80 ° C until the characteristic absorption of the isocyanate group disappeared in the IR spectrum, to obtain a resin having an average of 10 ethylenically unsaturated double bonds in one molecule. An organic solvent solution was obtained.

2-butanone was added to the obtained resin solution to obtain a solid content of 25
%, And then benzoin ethyl ether was added so as to be 2% with respect to the total amount of the paint to obtain a paint. The obtained coating material was applied on a polyethylene terephthalate film having a thickness of 50 μm so that the dry cured coating film thickness was 10 μm, the organic solvent was volatilized, and then the coating film was cured in the same manner as in Example 1. . The performance evaluation results of the obtained cured coating film are shown in Table 1.

Comparative Example 3 A reaction with "Vinylite VAGH" was carried out in the same manner as in Example 4 except that the reaction product (e) was used in place of the adduct mixture (f), and gelled at a reaction rate of 52%. Oops.

Example 5 78 parts of 4-methyl-2-pentanone kept at 80 ° C., 45 parts of methyl methacrylate, 40 parts of ethyl methacrylate, 50 parts of n-butyl methacrylate, 15 parts of 2-hydroxyethyl methacrylate , 0.3 parts of azobisisobutyronitrile and 20 parts of toluene were added dropwise over 2 hours, followed by reaction at 80 ° C for 3 hours, then 50 parts of toluene was added, followed by 80 ° C.
The mixture was reacted for 4 hours to obtain an organic solvent solution (solid content: 50%) of an acrylic polyol (g) having an average of about 40 hydroxyl groups in one molecule and an average molecular weight of 34500.

345 parts of the resulting acrylic polyol (g) solution was added at 80 ° C.
17.6 parts of the adduct mixture (b) obtained in the example, 0.02 part of hydroquinone, 0.4 part of tin octylate and 17.6 parts of 4-methyl-2-pentanone.
The solution was added dropwise over 5 minutes, and the reaction was continued at 80 ° C until the characteristic absorption of the isocyanate group disappeared in the IR spectrum.
An organic solvent solution of a resin having 10 ethylenically unsaturated double bonds was obtained.

To 90 parts of the resulting resin solution, 127.5 parts of 2-butanone, 127.5 parts of toluene, 5 parts of polyethylene glycol (degree of polymerization of 4) diacrylate and 50 parts of rutile titanium white were added,
The mixture was kneaded to obtain a white paint. The resulting white paint was applied on a tin-free steel plate with a roll coater to a dry-cured coating thickness of 30 μm, and the organic solvent was volatilized, followed by electron beam irradiation of 5 Mrad at 160 kV to cure the coating film. It was The performance evaluation results of the obtained cured coating film are shown in Table 1.

Comparative Example 4 A reaction with an acrylic polyol (g) was carried out in the same manner as in Example 5 except that the reaction product (a) obtained in Example 1 was used instead of the adduct mixture (b). Gelation occurred at a reaction rate of 67%.

Example 6 480 parts of 4-methyl-2-pentanone and 262 parts of ethyl hydroxyethyl cellulose “EHEC-Low” (trade name, manufactured by Hercules Co., Ltd.) were kept at 80 ° C., and the adduct mixture obtained in Example 4 was added thereto. (F) 62.8 parts, hydroquinone 0.06 part, dibutyltin dilaurate 0.9 part and 4-methyl-2-pentanone 147 parts were added dropwise over 30 minutes,
The reaction was continued at 80 ° C until the characteristic absorption of the isocyanate group disappeared in the IR spectrum, and a 4-methyl-2-pentanone solution of a resin having an average of about 20 ethylenically unsaturated double bonds in one molecule was obtained.

To the obtained resin solution 123.5 parts, 2-butanone 109.3 parts, toluene 109.3 parts, polyethylene glycol (polymerization degree 4) diacrylate 18 parts and phthalocyanine blue "Rionol Blue GLA" (trade name, manufactured by Toyo Ink Mfg. Co., Ltd.) )Four
0 part was added and kneaded to obtain a blue paint. The resulting blue paint was applied on a polyethylene terephthalate film with a thickness of 50 μm so that the dry cured coating film thickness would be 20 μm, and after evaporating the organic solvent, the coating film was cured by electron beam irradiation at 3 Mrad at 160 kV. . The performance evaluation results of the obtained cured coating film are shown in Table 1.
Shown in.

Comparative Example 5 A reaction with “EHEC-Low” was carried out in the same manner as in Example 6 except that the reaction product (e) obtained in Example 4 was used in place of the adduct mixture (f). Reaction rate 48
% Has gelled.

The test method and display of evaluation results are as follows.

2-Butanone rubbing: The coating number is rubbed with a 2-butanone-impregnated cloth, and the number of times of rubbing until the surface of the coated object is exposed is displayed.

Pencil hardness: Use "Uni" (trade name, manufactured by Mitsubishi Pencil Co., Ltd.). Passed 2H or more.

Adhesion: Displayed by the number of remaining grids when 100 pieces of grids 1mm wide and 1mm wide on the coating surface were cut with a knife and the cellophane adhesive tape was peeled off. 95 or more were passed.

Bendability: 1T bend and 2T bend. ○: No crack,
Δ: There are slight microcracks. Those that had no cracks when bent at 2T were accepted.

Gloss: Visual evaluation.

〔The invention's effect〕

The radiation-curable resin obtained by the present invention has excellent adhesiveness to substrates, processing adhesiveness, hardness, chemical resistance, water resistance, etc., as well as excellent curability, and extremely good high-speed workability. Since there is no increase in viscosity or gelation during reaction or storage, various materials such as those mentioned above can be added as they are or if necessary, finishing varnish such as metal or plastic, white coating, cosmetic coating, It can be widely used in the field of paints such as magnetic paints, printing inks, resist inks, adhesives, and photosensitive resin plates.

Claims (1)

[Claims] 1. A monohydroxy compound (A) having an ethylenically unsaturated double bond and a diisocyanate compound (B) are reacted at a ratio exceeding 0.5 mol of (B) to 1 mol of (A), The first step of obtaining a mixture (D) consisting of adduct body mixture (A) and (B) (C) and unreacted (B), (D), (B) is dissolved and (C) is substantially A second step of washing with a solvent that does not dissolve in water to obtain (C) by substantially removing unreacted (B), and reacting the compound (E) having 3 or more hydroxyl groups with (C) A method for producing a radiation-curable resin, which comprises three steps.