JP2017132855A - Unsaturated group-containing urethane prepolymer, resin composition for surface protection coat and polymerization cured product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an unsaturated group-containing urethane prepolymer that is soluble in water or alcohol, and can improve surface hardness while maintaining hydrophilicity, and a resin composition for surface protection coat comprising the same and a polymerization cured product thereof.SOLUTION: An unsaturated group-containing urethane prepolymer has a polyglycerol skeleton represented by formula (1) (where R is a dehydroxylated residue of a monool or polyol compound comprising a (meth) acryloyl group or a vinyl group, and m+n is an integer of 2-30).SELECTED DRAWING: None

Description

  The present invention relates to an unsaturated group-containing urethane prepolymer, a resin composition for a surface protective coating containing the same, and a polymerized cured product thereof.

As the active energy ray-curable resin having hydrophilicity, for example, a urethane bond-containing diol (meth) obtained by hydrolytic ring-opening reaction of a urethane bond-containing cyclic ketal (meth) acrylate compound described in Patent Document 1 An acrylate compound, a water-soluble (meth) acrylate compound having an ethylene oxide chain in the molecule described in Patent Document 2 and a water-soluble urethane acrylate compound are known.
Although these compounds have high solubility in water and alcohols, since the polyoxyalkylene skeleton itself is flexible, the hardness and scratch resistance of the cured product surface are insufficient.

JP 2006-151953 A JP-A-11-115305

Under such circumstances, a material excellent in both sufficient hydrophilicity and surface hardness or scratch resistance is required.
The present invention has been made to solve the above-described problems, and includes an unsaturated group-containing urethane prepolymer that is soluble in water or alcohols and can improve surface hardness while maintaining hydrophilicity. It aims at providing the resin composition for surface protection coats, and its polymerization hardened material.

（式中、Ｒは（メタ）アクリロイル基又はビニル基を含むモノオール又はポリオール化合物の脱水酸基残基を表し、ｍ＋ｎは２〜３０の整数を表す。）
〔２〕水又はアルコール類に可溶性である上記の不飽和基含有ウレタンプレポリマー。
〔３〕上記の不飽和基含有ウレタンプレポリマーを含む表面保護コート用樹脂組成物。
〔４〕上記の表面保護コート用樹脂組成物の光又は熱重合硬化物。 As a result of intensive studies, the inventors of the present application have made it possible to dissolve in water or alcohols by using a urethane prepolymer containing an unsaturated group having a specific structure. It has been found that the balance between hydrophilicity and surface hardness can be easily adjusted by changing the amount, and the present invention has been completed.
That is, this application includes the following inventions.
[1] An unsaturated group-containing urethane prepolymer having a polyglycerin skeleton represented by the formula (1).

(In the formula, R represents a dehydroxylated residue of a monool or polyol compound containing a (meth) acryloyl group or a vinyl group, and m + n represents an integer of 2 to 30.)
[2] The unsaturated group-containing urethane prepolymer which is soluble in water or alcohols.
[3] A resin composition for a surface protective coating comprising the unsaturated group-containing urethane prepolymer.
[4] A light or thermal polymerization cured product of the above resin composition for a surface protective coat.

  According to the present invention, there are provided an unsaturated group-containing urethane prepolymer, a resin composition for a surface protective coat, and a polymerized cured product that are soluble in water or alcohols and can improve surface hardness while maintaining hydrophilicity. can do.

In the present specification, “(meth) acryl” represents “methacryl” and / or “acryl”, and “(meth) acrylate” represents “methacrylate” and / or “acrylate”.
Each of the components shown below may be used alone or in combination of two or more.

（式中、Ｒは（メタ）アクリロイル基又はビニル基を含有するモノオール又はポリオール化合物の脱水酸基残基を表し、ｍ＋ｎは２〜３０の整数を表す。）
ここで、不飽和基含有ウレタンプレポリマーとは、分子内に部分的に重合した部位を有し、かつその端部において、重合可能な基、つまり、（メタ）アクリロイル基又はビニル基の不飽和基を含有するものを指し、例えば、２０００以下の分子量を有し、好ましくは、１０００〜２０００程度の分子量を有する。ここでの分子量は、ポリスチレン換算で、ゲルパーミエーションクロマトグラフィーにより求めた重量平均分子量を意味する。 [Unsaturated group-containing urethane prepolymer]
The unsaturated group-containing urethane prepolymer of the present invention is represented by the formula (1).

(In the formula, R represents a dehydroxylated residue of a monool or polyol compound containing a (meth) acryloyl group or a vinyl group, and m + n represents an integer of 2 to 30.)
Here, the unsaturated group-containing urethane prepolymer has a partially polymerized site in the molecule, and at the end thereof, a polymerizable group, that is, (meth) acryloyl group or vinyl group unsaturated. It refers to those containing a group, and has, for example, a molecular weight of 2000 or less, preferably a molecular weight of about 1000 to 2000. The molecular weight here means a weight average molecular weight determined by gel permeation chromatography in terms of polystyrene.

  The prepolymer of the formula (1) is obtained by reacting polyglycerin, an organic isocyanate compound, and a hydroxyl group-containing (meth) acrylic acid ester, or polyglycerin and an organic isocyanate having a (meth) acrylic group. It can be produced by reacting.

（式中、ｎは２〜３０の整数を表す。）
グリセリンの重合度は、２〜２５が好ましく、より好ましくは２〜８である。 Polyglycerin is a polymer represented by the formula (2) obtained by polycondensation by heating a plurality of glycerols in the presence of an alkali catalyst. In addition to this polymer, it may have a cyclic and branched structure. Specific examples include hexaglycerol and decaglycerol. The polyglycerin may be obtained from glycidol or epichlorohydrin.

(In the formula, n represents an integer of 2 to 30.)
As for the polymerization degree of glycerol, 2-25 are preferable, More preferably, it is 2-8.

  Examples of organic isocyanate compounds include isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, norbornane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, trimethylhexamethylene diisocyanate, naphthalene diisocyanate, And trifunctional organic isocyanate compounds such as hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and burettes and nurates of these organic diisocyanates. Of these, diisocyanate compounds such as isophorone diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate are preferable.

  Examples of the organic isocyanate having a (meth) acryl group include (meth) acryloyl isocyanate, 2- (meth) acryloyloxyethyl isocyanate, 1,1- (bisacryloyloxymethyl) ethyl isocyanate, and the like.

  Any hydroxyl group-containing (meth) acrylic acid ester may be used as long as it contains at least one hydroxyl group in the molecule, and the desired urethane prepolymer is obtained by controlling crosslinking and gelation by reaction with diisocyanate. From the standpoint of ease, one containing one hydroxyl group is preferred.

  Examples of the hydroxyl group-containing acrylic ester include hydroxyalkyl (meth) acrylates, polyol (meth) acrylates, alkylene oxide-added polyol (meth) acrylates, and those derived from epoxy resins and carboxylic acids.

  The hydroxyalkyl (meth) acrylates are preferably those in which (meth) acrylic acid is added to an oxirane ring-containing compound having about 2 to 12 carbon atoms. More specifically, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, 3-phenoxy-2-hydroxypropyl (meth) acrylate and the like can be mentioned.

  The polyol (meth) acrylates are preferably divalent to tetravalent polyol (meth) acrylates having about 2 to 10 carbon atoms. Specific examples include glycerin di (meth) acrylate, trimethylolpropane di (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol penta (meth) acrylate. .

  The alkylene oxide addition polyol (meth) acrylates preferably contain an alkylene oxide having about 2 to 10 carbon atoms (preferably about 2 to 8 carbon atoms). Examples thereof include alkylene oxide-added trimethylolpropane di (meth) acrylate, alkylene oxide-added pentaerythritol tri (meth) acrylate, and alkylene oxide-added dipentaerythritol penta (meth) acrylate.

Therefore, the “dehydroxylated residue of monool or polyol compound containing (meth) acryloyl group or vinyl group” in R of formula (I) may have one (meth) acryloyl group or vinyl group. It may be good or may have more than one. Moreover, it may have only a (meth) acryloyl group or a vinyl group, and in addition to one or a plurality of (meth) acryloyl groups or vinyl groups, regardless of the number of hydroxyl groups of the monool or polyol compound, One hydroxyl group-dehydroxylated residue may be included, or a plurality of hydroxyl group-dehydroxylated residues may be included. Furthermore, as long as it contains a dehydroxylation residue of one or more hydroxyl groups, it may contain one or more hydroxyl groups. The dehydroxylated residue is a residue derived from the compound or reactant constituting the prepolymer of the formula (1), for example, a hydrocarbon group having 30 or less carbon atoms (however, the carbon constituting this hydrocarbon group) May be substituted with one or more oxygen atoms, carbonyl groups, nitrogen atoms, amino groups, and the like.
By having such a structure, the number of polymerized polyglycerols, the number of hydroxyl groups therein, introduction of a hydroxyl group-containing (meth) acrylic acid ester having a plurality of (meth) acryloyl groups or vinyl groups in the molecule, ( By adjusting the number of hydroxyl groups in the dehydroxylation of the mono / polyol compound containing a (meth) acryloyl group or vinyl group and the number of unsaturated groups derived from the (meth) acryloyl group or vinyl group, hydrophilicity and surface hardness Can be adjusted appropriately.

  The unsaturated group-containing urethane prepolymer of the formula (1) can be composed as a resin composition that can be used for various applications. In particular, the resin composition preferably has a composition that can be cured by irradiation with active energy rays such as visible light, ultraviolet rays, radiation, infrared rays, and X-rays. Moreover, you may add an additive well-known in the said field in the range which does not impair the original function of the polymer of an unsaturated group containing urethane prepolymer. Examples thereof include a photopolymerization initiator or a polymerization initiator, a diluent, metal oxide fine particles, a leveling agent, a lubricity imparting agent, and other resins.

Examples of the photopolymerization initiator include hydroxycyclohexyl phenyl ketone, 1-phenyl-2-hydroxy-2-methylpropan-1-one, 2,2-dimethoxy-2-phenylacetophenone, benzophenone, 2-methyl [4 -(Methylthio) phenyl] -2-morpholino-1-propanone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane- 1-one, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 4- (2-acryloyloxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 4- ( 2-Methacryloyloxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone 2,4,6-trimethyl base down benzoyl diphenyl phosphine oxide.
The photopolymerization initiator is preferably contained in an amount of about 0.3 to 20 parts by weight and more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the unsaturated group-containing urethane prepolymer of the formula (1).

  Examples of the diluent include monoalkyl ethers of alkylene glycol, alkyl alcohols, alkyl carboxylic acid esters of alkylene glycol monoalkyl alcohol, ketones, alkyl carboxylic acid esters of alkyl alcohol, and the like. For example, those described in JP-A-2004-43790 are exemplified.

  As metal oxide fine particles, silicon oxide, zirconium oxide, titanium oxide, zinc oxide, antimony pentoxide, tin oxide, aluminum oxide, indium oxide, indium tin oxide, ferric oxide, cerium oxide, yttrium oxide, manganese oxide , Holmium oxide, copper oxide, bismuth oxide, cobalt oxide, cobalt tetroxide, iron tetroxide, magnesium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, Examples thereof include erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, scandium oxide, tantalum pentoxide, niobium pentoxide, iridium oxide, rhodium oxide, ruthenium oxide, and composite oxides obtained by combining these. It is suitable to use metal oxide fine particles having a particle diameter of 5 nm to 50 nm, and among them, 10 nm to 20 nm is preferable. Thereby, it becomes possible to adjust the refractive index of the resin composition.

Examples of the leveling agent and the lubricity-imparting agent include a copolymer of polyoxyalkylene and polydimethylsiloxane, a copolymer of polyoxyalkylene and fluorocarbon, and the like.
Examples of other resins include polyurethane resins, polyepisulfide resins, (meth) acrylic polymers such as polymethyl methacrylate (PMMA), allyl polymers, diethylene glycol bisallyl carbonate, polycarbonate, MS resin, cyclic polyolefin, and the like. Various synthetic resins are mentioned.
When other resins are included, the other resins are preferably contained in an amount of about 0.1 to 20 parts by weight with respect to 100 parts by weight of the unsaturated group-containing urethane prepolymer of the formula (1). Is more preferable.

  Also, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, tetra (1,2,2,6) , 6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylic acid ester, etc., hindered amine light stabilizer having 1,2,2,6,6-pentamethyl-4-piperidyl residue,

Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, n-octyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, Hindered phenols such as 4,4′-thiobis (3-methyl-6-tert-butylphenol), ditridecyl-3,3′-thiodipropionate, dilauryl-3,3′-thiodipropionate, bis [2-methyl-4- {3-n-alkyl (C ₁₂ or C ₁₄₎ thio propionyloxy} -5-t-butylphenyl] sulfur system such as the sulfides 3,5 di t-butyl-4 An antioxidant having a hydroxyphenyl residue or a 3-methyl-6-tert-butylphenyl residue,

Phosphite-based decolorizing agent,
Antifoaming agent such as silicone oil,
You may mix | blend well-known additives in the said field | areas, such as a silane coupling agent, a flame retardant, a filler, a matting agent, a photosensitizer, and an ultraviolet absorber.

The resin composition of the present invention may contain a solvent as necessary.
As the solvent, alcohols, glycols, aliphatic cyclic ketones, acetate esters and the like are used.
Examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol, and 1-methoxy-2-propanol.
Examples of glycols include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl Ether acetate, propylene glycol monobutyl ether acetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol Dipropyl ether, diethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether.
Examples of the aliphatic cyclic ketones include cyclohexanone, ortho, meta, and para-methylcyclohexanone.
Examples of acetate esters include ethyl acetate n-propyl acetate and n-butyl acetate.
Solvent naphtha, methyl ethyl ketone, or the like may be used.

As described above, the resin composition of the present invention can be cured by irradiating active energy rays of ultraviolet rays, radiation, infrared rays, X-rays, electron beams, particularly ultraviolet rays, or by heat, to obtain a molded body. be able to. Here, as a molded object, not only what was shape-processed by the specific shape but what has various forms is included. For example, the resin composition is poured between the base materials, irradiated with active energy rays and cured, and molded into a specific shape.
Examples of light sources for active energy rays include xenon lamps, carbon arcs, germicidal lamps, fluorescent lamps for ultraviolet rays, high pressure mercury lamps for copying, medium pressure mercury lamps, high pressure mercury lamps, ultrahigh pressure mercury lamps, electrodeless lamps, metal halide lamps, scanning types or Examples thereof include an electron beam by a curtain type electron beam acceleration path.
When hardening using such a light source, about 300-3000 mJ / cm < ² > is mentioned for the amount of active energy ray irradiation. In order to sufficiently cure the resin composition, active energy rays such as ultraviolet rays may be irradiated in an inert gas atmosphere such as nitrogen gas.
When heat is used, it is preferably about 30 to 60 minutes in the temperature range of 100 to 150 ° C.

Examples of the molded product of the present invention include molded products such as plastic lenses.
The molded product can be made by injecting a resin composition between a gasket made of polyvinyl chloride, ethylene vinyl acetate copolymer, etc. and two molds of the desired shape, and then irradiating with active energy rays such as ultraviolet rays. And a method of curing the resin composition of the present invention and peeling the molded body from the mold.

You may shape | mold the molded object of this invention, ie, a polymeric hardened | cured material, in a film form. The film is formed by a method known in the art, for example, extrusion molding or the like, or a method of forming a coating film on an appropriate base material using the above-described method and curing it, and then peeling the base material. Is exemplified.
Further, when an optical sheet such as a prism sheet is used, for example, the thickness after curing is suitably about 0.01 μm to 10 mm, preferably about 0.01 to 1000 μm, It is more preferable that the thickness be about ˜100 μm.

Furthermore, you may form the molded object of this invention as a laminated layer with respect to a base material. Specifically, methods such as brush coating, bar coater, applicator, roll coater or roller brush directly applied to the substrate, spray coating using an air spray or airless spray coater, shower coater or curtain flow coater, etc. The film can be laminated by a flow coating method (flow coating), a dipping method, a casting method, a method using a spin coating method, or the like.
Base materials include polyurethane resins, polyepisulfide resins, (meth) acrylic polymers such as polymethyl methacrylate (PMMA), allyl polymers, diethylene glycol bisallyl carbonate, polycarbonate, MS resins, cyclic polyolefins, and other synthetic resins. The base material which consists of is mentioned. The substrate may have any shape such as a flat plate shape, a curved plate shape, and a film shape.

  As described above, the resin composition of the present invention is cured into an arbitrary shape, for example, a prism lens sheet, an aspheric lens, a Fresnel lens, a lenticular lens, a spectacle lens, a liquid crystal display panel, and a color filter protective film. The present invention can be applied to various articles such as optical disk coating agents and adhesives, optical fiber core materials and clad materials, optical fiber connection adhesives, optical waveguide core materials and clad materials.

  Hereinafter, the present invention will be specifically described with reference to examples of the unsaturated group-containing urethane prepolymer, the resin composition, and the molded body of the present invention, but the present invention is not limited thereto.

Example 1
In a four-necked flask equipped with a stirrer, a condenser, and a thermometer, 93.2 g of polyglycerol (molecular weight 462), 0.030 g of di-t-butylhydroxyphenol, 0.030 g of p-methoxyphenol and 0.015 g of dioctyltin compound And stirred well at 55 ° C. until uniform. Subsequently, 56.9 g of 2-acryloyloxyethyl isocyanate was added dropwise to the flask little by little while paying attention to the reaction temperature. After completion of dropping, the mixture was aged at 60 ° C. for 3 hours. A part of the reaction solution was taken out, an infrared absorption spectrum was measured, and the end point of the reaction was confirmed from the disappearance of the absorption peak of the isocyanate group at 2280 cm ⁻¹ to obtain the intended urethane prepolymer.

(Example 2)
In a four-necked flask equipped with a stirrer, a condenser tube and a thermometer, 67.5 g of polyglycerin (molecular weight 462), 0.030 g of di-t-butylhydroxyphenol, 0.030 g of p-methoxyphenol and 0.015 g of dioctyltin compound And stirred well at 55 ° C. until uniform. Subsequently, 82.5 g of 2-acryloyloxyethyl isocyanate was added dropwise to the flask little by little while paying attention to the reaction temperature. After completion of dropping, the mixture was aged at 60 ° C. for 3 hours. A part of the reaction solution was taken out, an infrared absorption spectrum was measured, and the end point of the reaction was confirmed from the disappearance of the absorption peak of the isocyanate group at 2280 cm ⁻¹ to obtain the intended urethane prepolymer.

(Example 3)
In a four-necked flask equipped with a stirrer, a condenser, and a thermometer, 43.6 g of polyglycerin (molecular weight 462), 0.030 g of di-t-butylhydroxyphenol, 0.030 g of p-methoxyphenol and 0.015 g of dioctyltin compound. And stirred well at 55 ° C. until uniform. Subsequently, 106 g of 2-acryloyloxyethyl isocyanate was added dropwise to the flask little by little while paying attention to the reaction temperature. After completion of dropping, the mixture was aged at 60 ° C. for 3 hours. A part of the reaction solution was taken out, an infrared absorption spectrum was measured, and the end point of the reaction was confirmed from the disappearance of the absorption peak of the isocyanate group at 2280 cm ⁻¹ to obtain the intended urethane prepolymer.

(Comparative Example 1)
In a four-necked flask equipped with a stirrer, condenser and thermometer, 300 g of polyethylene glycol monoacrylate (PEG # 400) and 42.2 g of hexamethylene diisocyanate, 0.59 g of di-t-butylhydroxy-phenol as an antioxidant Then, 1.48 g of polymerization inhibitor p-methoxyphenol and 0.30 g of di-n-butyltin dilaurate were added and reacted at 80 ° C. for 2 hours. Two hours later, a part of the reaction solution was taken out, and the end point of the reaction was confirmed from the disappearance of the absorption peak of the isocyanate group at 2280 cm ^{−1 in} the infrared absorption spectrum, and the intended urethane prepolymer was obtained.

(Comparative Example 2)
In a four-necked flask equipped with a stirrer, a condenser and a thermometer, polypropylene glycol (number average molecular weight 4000) 300 g, isophorone diisocyanate 33.2 g, antioxidant di-t-butylhydroxy-phenol 0.07 g and dioctyl 0.035 g of a tin compound was added and reacted at 60 ° C. for 3 hours. Next, 18.2 g of 2-hydroxyethyl acrylate, 0.07 g of p-methoxyphenol as a polymerization inhibitor and 0.07 g of dioctyltin compound were added and reacted at 70 ° C. for 3 hours. A part of the reaction solution was taken out, and the end point of the reaction was confirmed from the disappearance of the absorption peak of the isocyanate group at 2280 cm ^{−1 in} the infrared absorption spectrum, and the intended urethane prepolymer was obtained.

(Physical property evaluation test)
Into the unsaturated group-containing urethane prepolymers obtained in Examples 1 to 3 and Comparative Examples 1 to 3, 5 parts by weight of a photopolymerization initiator (1-hydroxycyclohexyl phenyl ketone) is blended, and the bar is placed on the highly adhesive PET film. It was applied using a coater. This was irradiated with an active energy electron beam and subjected to crosslinking polymerization to form a resin sheet having a thickness of about 10 μm.
The following evaluation was performed about each resin sheet formed on the film.

(1) Water contact angle Using Drop Master 500 manufactured by Kyowa Interface Science Co., Ltd., the contact angle when distilled water was dropped onto the obtained resin sheet was measured.
(2) Pencil Hardness According to JIS K 5400, the pencil hardness of the coating film of the test piece was measured using a pencil scratch tester. While maintaining a pencil of various hardnesses at an angle of 45 °, a load of 750 g was applied from above, the resin sheet was scratched 1 cm, and the presence or absence of scratches was visually observed. Repeated 5 times, the highest hardness among the pencil hardnesses that were not scratched 5 times was defined as the hardness of the resin sheet.
(3) Solubility The unsaturated group-containing urethane prepolymers obtained in Examples 1 to 3 and the compounds of Comparative Examples 1 to 3 were mixed with water, ethanol and isopropyl alcohol, respectively, and the appearance was visually observed. At that time, the transparent one was evaluated as “◯”, the one having haze as “Δ”, and the one confirmed to be separated or precipitated as “×”.
Solubility 1 was mixed at a ratio of 20 parts by weight of solvent to 80 parts by weight of the obtained urethane prepolymer and the compounds of Comparative Examples 1 to 3, and Solubility 2 was obtained from the obtained urethane prepolymer and Comparative Example 1 Evaluation was made by mixing 50 parts by weight of the compound (3) to 50 parts by weight of the solvent.

※１：ＰＥＧ６００ジアクリレート（共栄社化学株式会社製）

* 1: PEG600 diacrylate (manufactured by Kyoeisha Chemical Co., Ltd.)

The unsaturated group-containing urethane prepolymers obtained in Examples 1 to 3 were soluble in water or alcohol, had high surface hardness, and had a low water contact angle. Therefore, this unsaturated group-containing urethane prepolymer is suitable as a material for imparting hydrophilicity to a coating agent for surface protection that is cured by active energy rays.
On the other hand, the unsaturated group-containing urethane prepolymers obtained in Comparative Examples 1 to 3 are not sufficient as hydrophilic materials because they do not dissolve in water or alcohol or have low hardness.

  The unsaturated group-containing urethane prepolymer of the present invention can be used as a material for various inks, paints, and coating agents in which it is desirable to avoid the use of solvents with strong odors such as toluene and ketone because it dissolves in water or alcohol. it can. Moreover, since the cured product obtained by polymerizing the resin composition containing this unsaturated group-containing urethane prepolymer has a low water contact angle and a high surface hardness, it is a substrate surface coating agent that requires hydrophilicity. It is also useful as a material.

Claims (4)

An unsaturated group-containing urethane prepolymer having a polyglycerin skeleton represented by the formula (1).

(In the formula, R represents a dehydroxylated residue of a monool or polyol compound containing a (meth) acryloyl group or a vinyl group, and m + n represents an integer of 2 to 30.)   The unsaturated group-containing urethane prepolymer according to claim 1, which is soluble in water or alcohols.   A resin composition for a surface protective coating comprising the unsaturated group-containing urethane prepolymer according to claim 1.   A photo- or heat-polymerized cured product of the resin composition for a surface protective coat according to claim 3.