JP2006299148A - Ultraviolet ray-curable resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet ray-curable resin composition which has excellent curability and can form cured products having excellent solvent resistance and flexibility. <P>SOLUTION: This ultraviolet ray-curable resin composition is characterized by comprising (A) a urethane prepolymer having at least one alicyclic epoxy group, (B) an oxetane compound having two or more oxetane ring structures, and (C) a cation photopolymerization initiator. The above-mentioned problems can be solved with the composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultraviolet curable resin composition applicable in various fields including the adhesive field.

  In various fields, studies on ultraviolet curable resin compositions capable of forming a cured coating film without going through a heating process have been underway, and in recent years, practical applications have been made in the fields of printing inks, adhesives, paints, and the like. It is becoming.

  As the ultraviolet curable resin composition, for example, a so-called radical polymerizable ultraviolet curable resin composition in which curing proceeds by radical polymerization such as an acrylic resin having an unsaturated double bond is known. However, the radical polymerizable ultraviolet curable resin composition has a practical problem that it is not easily cured in the presence of oxygen.

  For the purpose of solving the above problems, the study of a cationic polymerization type UV curable resin composition that is not affected by oxygen in the atmosphere has been underway, such as urethane alicyclic epoxy resin, cationic polymerizable A resin composition containing a substance and / or (meth) acrylate and a photopolymerization initiator is excellent in curability and can form a cured product excellent in glossiness and adhesion to a substrate. Is known (for example, see Patent Document 1).

However, the cured product obtained by irradiating the resin composition with a UV irradiation amount of a level that can be usually applied when UV-curing, approximately 1000 to 5000 mJ / cm ² as a guide, is apparently sufficiently cured. Even if it seems to have progressed, the gel fraction does not actually reach a sufficient level, and as a result, deterioration may occur due to the influence of an organic solvent or the like. That is, when the resin composition is used in, for example, a paint, it is difficult to form a coating film excellent in solvent resistance. When used in an adhesive, the adhesive strength is affected by an organic solvent. It has a problem that it may cause a decrease in the quality of the product.

  In addition, the ultraviolet curable resin composition includes an epoxy curable cationic polymerizable compound such as an epoxy resin, a compound having at least one oxetane ring, a cationic polymerization initiator, and a lubricity imparting agent. It has been reported that the composition can form a coating film excellent in performance such as processability, adhesion, and hardness (see, for example, Patent Document 2).

  However, since the UV-curable can coating composition uses an epoxy compound as the cationic polymerizable compound, the resulting cured coating is hard and brittle, and is required in the fields of adhesives and coatings. It was difficult to form a cured coating film having a level of flexibility. In addition, the flexibility required in the adhesive field or the like means that the cured coating film has sufficient followability to the substrate when a structure composed of the flexible substrate and the cured coating film is folded. In general, a level of flexibility that does not cause cracking of the cured coating film due to bending or the like is required.

  By the way, in the production line of precision equipment including electronic products, adhesives and paints that are curable with ultraviolet rays are often used from the viewpoint of preventing adverse effects on precision equipment due to heating. In the production line, the ultraviolet curable resin composition is usually used from the viewpoint of increasing the efficiency of the production process because the work cannot proceed to the next process until the adhesive or the like is sufficiently cured after being irradiated with the ultraviolet ray. Is required to have curability, that is, a property that allows curing to proceed sufficiently even with a small amount of ultraviolet irradiation (time).

  However, an ultraviolet curable resin composition that is excellent in curability and can form a cured product having excellent solvent resistance and flexibility has been investigated in various fields, but has not yet been found. is the current situation.

Japanese Patent Laid-Open No. 9-87357 JP-A-9-309950

  The problem to be solved by the present invention is to provide an ultraviolet curable resin composition capable of forming a cured product having excellent curability and excellent solvent resistance and flexibility.

Based on an ultraviolet curable resin composition comprising a conventionally known urethane prepolymer having an alicyclic epoxy group, a photocationic polymerization initiator, and other cationically polymerizable compounds. In order to improve the curability and the solvent resistance and flexibility of the resulting cured product, we have made extensive studies.
As the other cationic polymerizable compounds, epoxy compounds, vinyl ether compounds and the like are generally known. However, in the ultraviolet curable resin composition using these, the curability and the solvent resistance of the obtained cured product are obtained. And the flexibility could not be improved sufficiently.
In addition to the urethane prepolymer having an alicyclic epoxy group, a glycidyl group generally known as a cationic polymerization type functional group, that is, an epoxy group having no alicyclic structure, or an oxetane ring structure Although it was considered to use a urethane prepolymer or the like having curability, the curability and the like could not be sufficiently improved.
In further investigation, a resin composition comprising a urethane prepolymer having at least one alicyclic epoxy group, an oxetane compound having two or more oxetane ring structures, and a photocationic polymerization initiator. However, through a combination of various compositions, it has been found that the cured product is specifically excellent in curability and the obtained cured product is excellent in flexibility and the like.

  That is, the present invention contains a urethane prepolymer (A) having at least one alicyclic epoxy group, an oxetane compound (B) having two or more oxetane ring structures, and a photocationic polymerization initiator (C). It is related with the ultraviolet curable resin composition characterized by the above-mentioned.

  The number average molecular weight referred to in the present invention was measured in terms of polystyrene with a known molecular weight using an RI detector (refractive method) with tetrahydrofuran (THF) as an eluent and a flow rate of 1 ml / min. Represents a value. In the present invention, attention is paid to the number average molecular weight of the area showing the maximum molecular weight among the number average molecular weights having a specific molecular weight distribution.

  The ultraviolet curable resin composition of the present invention is excellent in curability and can form a cured product excellent in solvent resistance, flexibility, adhesion to organic materials, inorganic materials, and metal materials. Various adhesives such as adhesives for parts, various sealing agents such as pressure-sensitive adhesives and liquid crystal sealants, various resists such as liquid printed circuit board resists and dry film resists, coating agents for release paper, and coating agents for optical disks , Can coating agents, various coating agents such as surface coating agents for artificial leather / synthetic leather and powder coatings, and various ink vehicles such as lithographic inks, screen inks, flexographic inks, gravure inks and jet inks It can be used in a practical use and is extremely useful in practical use.

  The present invention contains as a main component a urethane prepolymer (A) having at least one alicyclic epoxy group, an oxetane compound (B) having two or more oxetane ring structures, and a photocationic polymerization initiator (C). In addition, it is an ultraviolet curable resin composition containing various additives as required.

First, the urethane prepolymer (A) having an alicyclic epoxy group used in the present invention will be described.
The urethane prepolymer (A) having an alicyclic epoxy group used in the present invention is a urethane prepolymer having at least one alicyclic epoxy group in the molecule.

  The alicyclic epoxy group possessed by the urethane prepolymer (A) is an epoxy in which one common oxygen atom is bonded to two adjacent carbon atoms among the carbon atoms forming the alicyclic structure. Refers to the group. Such an alicyclic epoxy group is opened by irradiation with ultraviolet rays in the presence of a photocationic polymerization initiator (C) described later, and the polymerization reaction proceeds.

  At least one alicyclic epoxy group is preferably present in the urethane prepolymer (A), and more preferably 2 to 4 alicyclic epoxy groups are present. By using the urethane prepolymer (A) having an alicyclic epoxy group within the above range, the ultraviolet curable resin composition of the present invention has good curability and is good for the obtained cured product. Flexibility can be imparted.

  The alicyclic epoxy group may be present at the molecular end or side chain of the urethane prepolymer (A), but in consideration of improving the curability of the resulting ultraviolet curable resin composition, It is preferable to use a urethane prepolymer having an alicyclic epoxy group at the terminal.

  The urethane prepolymer generally has a relatively low molecular weight, but those skilled in the art also have a number average molecular weight of several tens of thousands, which is also called a urethane prepolymer. Urethane prepolymers having a number average molecular weight of tens of thousands can be used. The number average molecular weight of the area showing the maximum molecular weight measured by size exclusion chromatography of the urethane prepolymer (A) used in the present invention is preferably in the range of 5000 to 100,000, preferably in the range of 8000 to 30000. It is more preferable to use one. By using the urethane prepolymer (A) having a number average molecular weight within the above range, an ultraviolet curable resin composition having excellent flexibility and good adhesion to organic materials, inorganic materials, and metal materials. Can be obtained.

  In the urethane prepolymer (A), for example, the polyol (a) and the polyisocyanate (b), the isocyanate group of the polyisocyanate (b) is excessive with respect to the hydroxyl group of the polyol (a). A urethane prepolymer having an isocyanate group at the molecular end is produced by reacting under conditions, and then produced by reacting the urethane prepolymer with an alicyclic epoxy compound (c) having one hydroxyl group. be able to.

  As said polyol (a) which can be used when manufacturing the said urethane prepolymer (A), polyether polyol, polyester polyol, a polycarbonate polyol etc. can be used individually, or can use 2 or more types together, for example.

  Examples of the polyether polyol include polyether polyols obtained by reacting a reaction initiator having two or more active hydrogen-containing groups with alkylene oxide, urethane-modified polyether polyols, polyether ester copolymer polyols, polymer polyols, PHD (abbreviation of polyharnsstoff) polyether polyol and the like can be used.

  Examples of the reaction initiator that can be used in producing the polyether polyol include water, ethylene glycol, propylene glycol, butanediol, glycerin, trimethylolpropane, hexanetriol, triethanolamine, diglycerin, pentaerythritol, and methyl. Glucosides, sorbitol, sucrose, aliphatic amine compounds, aromatic amine compounds, sucrose amine compounds, phosphoric acid, acidic phosphate esters, and the like can be used.

  As said alkylene oxide, ethylene oxide, a propylene oxide, tetrahydrofuran etc. can be used individually, or 2 or more types can be used together, for example.

  As the polyether polyol, it is preferable to use polypropylene glycol.

  Examples of the polyester polyol that can be used as the polyol (a) include a polyester polyol obtained by reacting a low molecular weight polyol and a polycarboxylic acid, and a polyester polyol obtained by ring-opening polymerization of a cyclic ester compound. .

  Examples of the low molecular weight polyol include ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 3,3-dimethylol heptane, 1,4-cyclohexanedimethanol, neopentyl glycol, diethylene glycol, dipropylene glycol, glycerin, trimethylol propane, etc. can be used, and these can be used alone or in combination of two or more. Can do.

  As the polycarboxylic acid, for example, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, orthophthalic acid, isophthalic acid, terephthalic acid and the like can be used, and these are used alone or in combination of two or more. be able to.

  As the cyclic ester compound, for example, ε-caprolactone and δ-valerolactone can be used.

  Moreover, when manufacturing the said urethane prepolymer (A), the compound which has an active hydrogen which can react with an isocyanate group other than the said polyol (a) as needed can be used.

  As the compound having active hydrogen capable of reacting with the isocyanate group, for example, a compound generally known as a chain extender, such as a low molecular weight polyol, an aliphatic amine, an aromatic amine, or an alkanolamine, may be used. it can.

  As said low molecular weight polyol, the thing similar to the low molecular weight polyol illustrated as what can be used when manufacturing the said polyester polyol can be used.

  Examples of the polyisocyanate (b) that can be used for producing the urethane prepolymer (A) include 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 2,2′-diphenylmethane diisocyanate, and polymethylene poly (polyethylene). Aromatic diisocyanates such as phenyl polyisocyanate, carbodiimidized diphenylmethane polyisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, tetramethylxylene diisocyanate, or isophorone diisocyanate , Dicyclohexylmethane diisocyanate, hydrogenated xylylene diisocyanate, norbornene diisocyanate, etc. Aliphatic diisocyanates such as socyanate, hexamethylene diisocyanate, dimer acid diisocyanate, etc. can be used, and these can be used alone or in combination of two or more, among which 4,4′-diphenylmethane diisocyanate should be used. Is preferred.

  As the alicyclic epoxy compound (c) having one hydroxyl group that can be used for producing the urethane prepolymer (A), for example, the following structural formulas (1) to (4) can be used.

  Examples of the alicyclic epoxy compound represented by the structural formula (1) include commercially available compounds such as ETHB, Epolide HD-300, Epolide HD-302 (manufactured by Daicel Chemical Industries, Ltd.). Can be used.

  In the method for producing the urethane prepolymer (A), the polyol (a) and the polyisocyanate (b) are an isocyanate group of the polyisocyanate (b) with respect to 1 equivalent of a hydroxyl group of the polyol (a). It is preferable to make it react in the range from which the equivalent ratio of becomes 1.1-5.0, and it is more preferable to make it react in the range of 2.0-3.0. By making it react by the equivalent ratio in the said range, the remarkable viscosity raise of the ultraviolet curable resin composition of this invention can be suppressed, and it becomes possible to obtain the hardened | cured material which has favorable softness | flexibility.

  The urethane prepolymer having an isocyanate group at the molecular end and the alicyclic epoxy compound (c) having one hydroxyl group are equivalent to 1 equivalent of the hydroxyl group of the alicyclic epoxy compound (c). The equivalent ratio of the isocyanate group of the urethane prepolymer having an isocyanate group at the molecular terminal is preferably reacted in the range of 0.8 to 1.2, more preferably in the range of 0.9 to 1.0. preferable. By using the urethane prepolymer (A) obtained by reacting at an equivalent ratio within the above range, it is possible to obtain an ultraviolet curable resin composition capable of forming a cured product having good flexibility. It becomes.

  When the polyol (a), the polyisocyanate (b), and the alicyclic epoxy compound (c) are reacted according to the method for producing the urethane prepolymer (A), the temperature is generally in the range of 70 to 100 ° C. It is preferable to react them for about 2 to 15 hours.

  Next, the oxetane compound (B) having two or more oxetane ring structures used in the present invention will be described.

  The oxetane compound (B) having two or more oxetane ring structures has two or more oxetane ring structures represented by the following structural formula (5) in the molecule, and is a photocationic polymerization initiator (C ) In the presence of UV to open the ring, and the polymerization reaction proceeds.

  The oxetane compound (B) preferably has 2 to 4 oxetane ring structures in the molecule, and more preferably 2 oxetane rings. The oxetane compound (B) having an oxetane ring structure in the above range can improve the curability of the ultraviolet curable resin composition of the present invention and can impart good flexibility to the obtained cured product. It becomes possible.

  As the oxetane compound (B) having two or more oxetane ring structures, for example, compounds represented by the following general formulas (6) and (7) can be used alone or in combination of two or more.

In the general formulas (6) and (7), R ₁ is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, an allyl group, an aryl group, an aralkyl group, a furyl group, or It represents a thienyl group, R ₂ represents a divalent organic residue, and Z represents an oxygen atom or a sulfur atom.

Examples of the linear, branched or cyclic alkyl group having 1 to 6 carbon atoms represented by R ₁ include a methyl group, an ethyl group, an n- or i-propyl group, an n-, i- or t- group. A butyl group, a pentyl group, a hexyl group, a cyclohexyl group, and the like; and an aryl group such as a phenyl, naphthyl, tolyl, and xylyl group; and an aralkyl group such as a benzyl and phenethyl group It is.

In the general formula (6), examples of the divalent organic residue represented by R ₂ include a linear, branched, or cyclic alkylene group and a poly (oxy) having 4 to 30 carbon atoms. Alkylene) group, phenylene group, xylylene group, and structures represented by the following general formulas (8) and (9).

The linear, branched or cyclic alkylene group constituting R ₂ has 1 carbon atom such as methylene group, ethylene group, 1,2- or 1,3-propylene group, butylene group, cyclohexylene group and the like. It is preferably an alkylene group of ˜15. The poly (oxyalkylene) group having 4 to 30 carbon atoms is preferably one having 4 to 8 carbon atoms, for example, a poly (oxyethylene) group or a poly (oxypropylene) group. Is preferred.

In the general formula (8), R ₃ represents an oxygen atom, a sulfur atom, CH ₂ , NH, SO, SO ₂ , C (CF ₃ ) ₂ or C (CH ₃ ) ₂ .

In the general formula (9), R ₄ represents an alkylene group having 1 to 6 carbon atoms, an arylene group, and a functional group represented by the following general formula (10).

  In the general formula (10), n represents an integer of 1 to 6, and m represents an integer of 1 to 15.

  As said general formula (10), it is preferable that m is an integer of 1-3.

  Examples of the oxetane compound (B) include Aron oxetane OXT-221 (bis [1-ethyl (3-oxetanyl)] methyl ether, manufactured by Toagosei Co., Ltd.), OXT-121 (1,4-bis [( 3-ethyl-3-oxetanylmethoxy) methyl] benzene, manufactured by Toa Gosei Co., Ltd.) and the like can be preferably used from the viewpoint of availability.

Next, the photocationic polymerization initiator (C) used in the present invention will be described.
The cationic photopolymerization initiator (C) used in the present invention has the urethane prepolymer (A) having the alicyclic epoxy and the oxetane ring structure when the ultraviolet resin composition of the present invention is irradiated with ultraviolet rays. Cationic polymerization of the oxetane compound (B) can be initiated.

As the cationic photopolymerization initiator (C), for example, the cation moiety is aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium, (2,4-cyclopentadien-1-yl) [(1-methyl Ethyl) benzene] -Fe cation, and the anion moiety is substituted with BF ₄ −, PF ₆ −, SbF ₆ −, [BX ₄ ] ⁻ , where X is substituted with at least two fluorine or trifluoromethyl groups The onium salt composed of a phenyl group) can be used alone or in combination of two or more.

  Examples of the aromatic sulfonium salt include bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluoroantimonate, and bis [4- (diphenyl). Sulfonio) phenyl] sulfide bistetrafluoroborate, bis [4- (diphenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, diphenyl-4- (phenylthio) phenylsulfonium hexafluorophosphate, diphenyl-4- (phenylthio) ) Phenylsulfonium hexafluoroantimonate, diphenyl-4- (phenylthio) phenylsulfonium tetrafluoroborate, diphenyl-4- (phenylthio) E) Phenylsulfonium tetrakis (pentafluorophenyl) borate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, bis [4- ( Di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bishexafluoroantimony Bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bistetrafluoroborate, bis [4- ( Di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate and the like can be used.

  Examples of the aromatic iodonium salt include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis (pentafluorophenyl) borate, bis (dodecylphenyl) iodonium hexafluorophosphate, Bis (dodecylphenyl) iodonium hexafluoroantimonate, bis (dodecylphenyl) iodonium tetrafluoroborate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium Hexafluorophosphate, 4-methylphenyl-4- (1-methyl Ethyl) phenyliodonium hexafluoroantimonate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium tetrafluoroborate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium tetrakis (pentafluorophenyl) borate Etc. can be used.

  Examples of the aromatic diazonium salt include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, and phenyldiazonium tetrakis (pentafluorophenyl) borate.

  Examples of the aromatic ammonium salt include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2-cyanopyridinium tetrafluoroborate, 1-benzyl 2-cyanopyridinium tetrakis (pentafluorophenyl) borate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluorophosphate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluoroantimonate, 1- (naphthylmethyl) -2-Cyanopyridinium tetrafluoroborate, 1- (naphthylmethyl) -2-cyanopyridinium tetrakis (pentafluorophenyl) borate, and the like can be used.

  (2,4-Cyclopentadien-1-yl) [(1-methylethyl) benzene] -Fe salt includes (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene]. -Fe (II) hexafluorophosphate, (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -Fe (II) hexafluoroantimonate, 2,4-cyclopentadien-1-yl ) [(1-Methylethyl) benzene] -Fe (II) tetrafluoroborate, 2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -Fe (II) tetrakis (pentafluorophenyl) Borate or the like can be used.

  Examples of the cationic photopolymerization initiator (C) include CPI-100P, CPI-100A (manufactured by San Apro Co., Ltd.), UVI-6990, UVI-6922, UVI-6976 (manufactured by Dow Chemical Japan ( Co., Ltd.), SP-150, SP-170 (above, manufactured by Asahi Denka Kogyo Co., Ltd.), FC-508, FC-512 (above, manufactured by 3M), CI-5102 (above, Nippon Soda Co., Ltd.) Irgacure 250 (manufactured by Ciba Specialty Chemicals Co., Ltd.), RHODROSIL PHOTOINITIATOR 2074 (manufactured by Rhodia Japan Co., Ltd.), and the like.

  In addition, the ultraviolet curable resin composition of the present invention includes two or more alicyclic epoxies in addition to the urethane prepolymer (A), the oxetane compound (B), and the photocationic polymerization initiator (C). It is preferable to use together an alicyclic epoxy compound (D) other than the urethane prepolymer (A) having a group. By using the alicyclic epoxy compound (D) in combination, the curability of the ultraviolet curable resin composition of the present invention can be significantly improved.

  An alicyclic epoxy group is an oxygen atom common to two carbon atoms (usually adjacent to each other) among the cyclically bonded carbon atoms that form the aliphatic ring of an alicyclic compound. An epoxy group with one bonded.

  The alicyclic epoxy compound (D) preferably has 2 to 4 alicyclic epoxy groups in the molecule, and more preferably has 2 alicyclic epoxy groups. By using the alicyclic epoxy compound having an alicyclic epoxy group in the above range, the curability of the ultraviolet curable resin composition of the present invention can be significantly improved, and further obtained by ultraviolet irradiation. It is possible to maintain good flexibility of the cured product.

  Examples of the alicyclic epoxy compound having two alicyclic epoxy groups other than the urethane prepolymer (A) include 3,4-epoxycyclohexylmethyl-3,4- represented by the following general formula (11). Epoxycyclohexanecarboxylate (compound in which k is 0), caprolactone-modified product thereof (wherein k is a compound in 1), trimethylcaprolactone-modified product (structural formula (12) and structural formula (13)) And its valerolactone-modified product (Structural Formula (14) and Structural Formula (15)) and the compound represented by Structural Formula (16) can be used, among them, 3,4-epoxycyclohexylmethyl-3, It is preferable to use 4-epoxycyclohexanecarboxylate (a compound in which k is 0).

  In the general formula (11), k represents 0 or 1.

  Examples of the 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate represented by the general formula (11) and its caprolactone modified product include, for example, Celoxide 2021, Celoxide 2021A, Celoxide 2021P, Celoxide 2080, Celoxide 2081, Celoxide 2083, Celoxide 2085 (manufactured by Daicel Chemical Industries, Ltd.), Cyracure UVR-6105, Cyracure UVR-6107, Cyracure UVR-6110 (manufactured by Dow Chemical Japan Co., Ltd.) and the like are commercially available.

  Examples of the adipic ester-based alicyclic epoxy compound represented by the general formula (16) include commercially available Cyracure UVR-6128, ERL4289, ERL4299 (above, manufactured by Dow Chemical Japan Co., Ltd.) and the like. Yes.

  Moreover, as an alicyclic epoxy compound other than the said urethane prepolymer (A) which has three alicyclic epoxy groups, the compound shown by following General formula (17) can be used.

  In general formula (17), n1 and n2 are each independently 0 or 1, and they may be the same or different.

  As the alicyclic epoxy compound represented by the general formula (17), for example, Epleido GT300, Epolide GT301, Epolide GT302 (manufactured by Daicel Chemical Industries, Ltd.) and the like are commercially available.

  Moreover, as an alicyclic epoxy compound other than the said urethane prepolymer (A) which has four alicyclic epoxy groups, the compound shown, for example by the following general formula (18) can be used.

  In the general formula (18), n3 to n6 each independently represent 0 or 1, and they may be the same or different.

  As the alicyclic epoxy compound represented by the general formula (18), for example, Epolide GT400, Epolide GT401, Epolide GT403 (manufactured by Daicel Chemical Industries, Ltd.) and the like are commercially available.

Next, the manufacturing method of the ultraviolet curable resin composition of this invention is demonstrated.
The ultraviolet curable resin composition of the present invention includes, for example, the urethane prepolymer (A) and the oxetane compound (B) using a sealed planetary mixer, and the alicyclic epoxy compound (D) as necessary. It can be manufactured by mixing and stirring until uniform, and then mixing and stirring the photocationic polymerization initiator (C).

  The mass ratio [(A) / (B)] of the urethane prepolymer (A) and the oxetane compound (B) in the ultraviolet curable resin composition of the present invention is in the range of 20/80 to 80/20. It is preferable that it is in the range of 50/50 to 75/25. The ultraviolet curable resin composition having a mass ratio in the above range is more excellent in curability and flexibility and excellent in adhesion to organic materials, inorganic materials, and metal materials.

  Moreover, when using together alicyclic epoxy compound (D) other than the said urethane prepolymer (A) which has a 2 or more alicyclic epoxy group, the said oxetane compound (B) and the said alicyclic epoxy are used. It is preferable that mass ratio [(B) / (D)] with a compound (D) is the range of 30 / 70-99 / 1. The ultraviolet curable resin composition having a mass ratio in the above range is more curable and can maintain good flexibility of the obtained cured product, and can be used for organic materials, inorganic materials, and metal materials. It is possible to maintain good adhesion.

  Moreover, it is preferable to use the said photocationic polymerization initiator (C) in 0.5-20 mass% with respect to the whole quantity of the ultraviolet curable resin composition of this invention, and the range of 1-10 mass%. It is more preferable to use in. The ultraviolet curable resin composition containing the cationic photopolymerization initiator (C) in the above range has a good curability, and the amount of acid remaining in the obtained cured product is at a level that can be almost ignored. Therefore, it is possible to suppress deterioration of the base material such as metal due to the acid.

  In the ultraviolet curable resin composition of the present invention, various additives can be used as necessary as long as the effects of the present invention are not impaired. Examples of the additive include a silane coupling agent, a filler, a thixotropic agent, a sensitizer, other polyols other than the various polyols described above, a leveling agent, an antioxidant, a tackifier, a wax, a heat stabilizer, Light stabilizer, fluorescent brightener, foaming agent, thermoplastic resin, thermosetting resin, organic pigment, inorganic pigment, organic solvent, dye, conductivity imparting agent, antistatic agent, moisture permeability improver, water repellent, Hollow foam, crystal water-containing compound, flame retardant, water-absorbing agent, moisture-absorbing agent, deodorant, foam stabilizer, antifoaming agent, antifungal agent, preservative, algaeproofing agent, pigment dispersant, inert gas, blocking Inhibitors, hydrolysis inhibitors, organic and inorganic water-soluble compounds and the like can be used in combination.

  Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ-methacryloxy. Propyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, γ-chloropropyltrimethoxysilane, or the like can be used.

  As the filler, for example, calcium carbonate, aluminum hydroxide, barium sulfate, kaolin, talc, carbon black, alumina, magnesium oxide, inorganic or organic balloon, lithia tourmaline, activated carbon and the like can be used.

  As the thixotropic agent, surface-treated calcium carbonate, fine powder silica, bentonite, zeolite and the like can also be used.

The ultraviolet curable resin composition of the present invention is applied to a substrate made of paper, wood, plastic, metal, etc. to a thickness of 1 to 500 μm using a roll coater or the like, and then the applied surface is irradiated with ultraviolet rays. By doing so, it is possible to form a cured coating film. The dose of ultraviolet rays is preferably from ^{50~5000mJ / cm 2, 100~3000mJ / cm} 2 is more preferable. Since the ultraviolet curable resin composition of the present invention can be sufficiently cured even at a relatively low dose, generally 100 to 1000 mJ / cm ² , Damage can be suppressed. When irradiating the ultraviolet rays, for example, a known lamp such as a xenon lamp, a xenon-mercury lamp, a metal halide lamp, a high-pressure mercury lamp, or a low-pressure mercury lamp can be used. In addition, all said ultraviolet irradiation amount is based on the value measured in the wavelength range of 300-390 nm using UV checker UVR-N1 (made by Japan Battery Co., Ltd.).

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

[Synthesis Example 1] (Synthesis example of urethane prepolymer (I) having an alicyclic epoxy group)
A clean flask was charged with 601 parts by mass of polypropylene glycol (hydroxyl equivalent: 1000) and 227 parts by mass of 4,4′-diphenylmethane diisocyanate while stirring under a nitrogen atmosphere (isocyanate group equivalent / hydroxyl group equivalent = 3.00). The contents were reacted at 90 ° C. for 3 hours while stirring under a nitrogen atmosphere.

  Next, with further stirring, 172 parts by mass of the compound represented by the structural formula (1) (ETHB, manufactured by Daicel Chemical Industries, Ltd.) was added (isocyanate group equivalent / hydroxyl group equivalent = 0.90) under a nitrogen atmosphere. The contents were reacted at 90 ° C. for 3 hours with stirring to obtain a urethane prepolymer (I) having an alicyclic epoxy group. The number average molecular weight of the area showing the maximum molecular weight measured by size exclusion chromatography (SEC) of the obtained urethane prepolymer (I) was 15000.

[Synthesis Example 2] (Synthesis example of urethane prepolymer (II) having an alicyclic epoxy group)
A clean flask was charged with 796 parts by mass of polypropylene glycol (with a hydroxyl group equivalent of 1000) and 148 parts by mass of 4,4′-diphenylmethane diisocyanate while stirring under a nitrogen atmosphere (equivalent to isocyanate group equivalent / hydroxyl group equivalent = 1.50). The contents were reacted at 90 ° C. for 7 hours with stirring under a nitrogen atmosphere.

  Next, while further stirring, 56 parts by mass of the compound represented by the structural formula (1) was charged (isocyanate group equivalent / hydroxyl group equivalent = 0.90), and reacted at 90 ° C. for 3 hours to have an alicyclic epoxy group. A urethane prepolymer (II) was obtained. The number average molecular weight of the area showing the maximum molecular weight measured by size exclusion chromatography (SEC) of the obtained urethane prepolymer (II) was 28,000.

[Synthesis Example 3] (Synthesis example of urethane prepolymer (III) having an alicyclic epoxy group)
Obtained by reacting 209 parts by mass of polypropylene glycol (with a hydroxyl group equivalent of 1000), 261 parts by mass of polypropylene glycol (with a hydroxyl group equivalent of 200), neopentyl glycol, 1,6-hexanediol and adipic acid in a clean flask The polyester diol (having a hydroxyl group equivalent of 1000) was charged in an amount of 52 parts by mass, and while stirring in a nitrogen atmosphere, 82 parts by mass of tolylene diisocyanate was added (isocyanate group equivalent / hydroxyl group equivalent = 0.60). The contents were reacted at 90 ° C. for 2.5 hours with stirring.

  Subsequently, 235 parts by mass of 4,4′-diphenylmethane diisocyanate was added with further stirring (isocyanate group equivalent / hydroxyl group equivalent = 3.00), and the contents were reacted at 90 ° C. for 2.5 hours while stirring in a nitrogen atmosphere. I let you.

  Next, 161 parts by mass of the compound represented by the structural formula (1) was charged with further stirring (isocyanate group equivalent / hydroxyl group equivalent = 0.90), and the contents were stirred at 90 ° C. for 3 hours while stirring in a nitrogen atmosphere. By reacting, a urethane prepolymer (III) having an alicyclic epoxy group was obtained. The number average molecular weight of the area showing the maximum molecular weight measured by size exclusion chromatography (SEC) of the obtained urethane prepolymer (III) was 9000.

[Synthesis Example 4] (Synthesis example of urethane prepolymer (IV) having an alicyclic epoxy group)
A clean flask was charged with 885 parts by mass of polypropylene glycol (with a hydroxyl group equivalent of 5000), and while stirring in a nitrogen atmosphere, 66 parts by mass of 4,4′-diphenylmethane diisocyanate (isocyanate group equivalent / hydroxyl group equivalent = 3.00). The contents were reacted at 90 ° C. for 7 hours while stirring under a nitrogen atmosphere.

  Next, 49 parts by mass of the compound represented by the structural formula (1) was charged (isocyanate group equivalent / hydroxyl group equivalent = 0.90), and the contents were reacted at 90 ° C. for 3.5 hours while stirring in a nitrogen atmosphere. A urethane prepolymer (IV) having an alicyclic epoxy group was obtained. The number average molecular weight of the area showing the maximum molecular weight measured by size exclusion chromatography (SEC) of the obtained urethane prepolymer (IV) was 83,000.

[Synthesis Example 5] (Synthesis Example of Urethane Prepolymer (V) Having Oxetane Ring Structure)
A clean flask was charged with 615 parts by weight of polypropylene glycol (with a hydroxyl group equivalent of 1000) and 228 parts by weight of 4,4′-diphenylmethane diisocyanate while stirring under a nitrogen atmosphere (isocyanate group equivalent / hydroxyl group equivalent = 3.00). ), And the contents were reacted at 90 ° C. for 3 hours while stirring under a nitrogen atmosphere.

  Next, with further stirring, 157 parts by mass of a compound of the following structural formula (19) (Aron Oxetane OXT-101, manufactured by Toagosei Co., Ltd.) was added (isocyanate group equivalent / hydroxyl group equivalent = 0.90) under a nitrogen atmosphere. The contents were allowed to react at 90 ° C. for 2.5 hours with stirring to obtain a urethane prepolymer (V) having an oxetane ring structure.

[Synthesis Example 6] (Synthesis example of urethane prepolymer (VI) having an epoxy group other than an alicyclic epoxy group)
648 parts by mass of polypropylene glycol (hydroxyl equivalent is 1000) is charged into a clean flask, and 244 parts by mass of 4,4′-diphenylmethane diisocyanate is added while stirring under a nitrogen atmosphere (isocyanate group equivalent / hydroxyl group equivalent = 3.00). ), And the contents were reacted at 90 ° C. for 3 hours while stirring under a nitrogen atmosphere.

  Next, with further stirring, 108 parts by mass of the compound of the following structural formula (20) (glycidol, manufactured by Daicel Chemical Industries, Ltd.) was charged (isocyanate group equivalent / hydroxyl group equivalent = 0.90) and stirred in a nitrogen atmosphere. Then, the contents were reacted at 90 ° C. for 3 hours to obtain a urethane prepolymer (VI) having a glycidyl group.

[Example 1]
In a closed planetary mixer, the urethane prepolymer (I) and OXT-221 (bis [1-ethyl (3-oxetanyl)] methyl ether, manufactured by Toa Gosei Co., Ltd.) are charged and stirred until uniform. By mixing. Next, CPI-100P (diphenyl-4- (phenylthio) phenylsulfonium hexafluorophosphate 50% by mass solution of propylene carbonate: manufactured by San Apro Co., Ltd.) was mixed and stirred, whereby the ultraviolet curable resin composition of the present invention was mixed. Obtained.

[Examples 2-8, Comparative Examples 1-11]
An ultraviolet curable resin composition was prepared in the same manner as in Example 1 except that the urethane prepolymer (I), OXT-221 and CPI-100P were replaced with those described in Table 1 and Table 2. Was prepared.

  The curability, solvent resistance and flexibility of the ultraviolet curable resin compositions of Examples 1 to 8 and Comparative Examples 1 to 11 were evaluated by the methods described below.

[Evaluation method of curability]
Finger touch evaluation Using a bar coater, the UV curable resin composition was applied on a polypropylene plate to a thickness of 50 μm, and the UV irradiation amount was set to 145 mJ / cm ² every time it passed through the apparatus. Polypropylene coated with the ultraviolet curable resin composition using a conveyor type ultraviolet irradiation device CSOT-40 (manufactured by Nippon Battery Co., Ltd., using a high-pressure mercury lamp, strength 120 W / cm, conveyor speed 10 m / min) The plate was passed once, three times and five times, and the coated surface of the ultraviolet curable resin composition was irradiated with ultraviolet rays. The degree of curing of the coating film was evaluated by pressing the surface of the coating film after irradiation with a finger. In addition, said ultraviolet irradiation amount is the value measured in the wavelength range of 300-390 nm using UV checker UVR-N1 (Nippon Battery Co., Ltd. product).

A: Completely cured to form a film.
○: A film is formed, but there is an uncured part.
Δ: Although the curing partially proceeds, a film is not formed.
X: No change before UV irradiation.

[Evaluation method of solvent resistance]
Evaluation by gel fraction Using a bar coater, the UV curable resin composition was applied on a polypropylene plate to a thickness of 50 μm so that the UV irradiation amount was 145 mJ / cm ² each time it passed through the apparatus. Using a set ultraviolet irradiation device CSOT-40 (manufactured by Nippon Battery Co., Ltd., using a high-pressure mercury lamp, strength 120 W / cm, conveyor speed 10 m / min), a polypropylene plate coated with the ultraviolet curable resin composition was applied. After passing 10 times and irradiating the application surface of the ultraviolet curable resin composition with ultraviolet rays, it was cured for 7 days in an atmosphere of 23 ° C. and 50% relative humidity, and peeled from the polypropylene plate to produce a film. The obtained film was immersed in ethyl acetate for 24 hours and then dried at 107 ° C. for 1 hour, and the gel fraction (mass%) was calculated based on the following formula.

N = W _b / W _a × 100
N: gel fraction (mass%)
W _a : Mass of the sample before immersion (g)
W _b : weight of the sample after drying (g)

Judgment standard ○ ・ ・ ・ The gel fraction is 80% by mass or more.
Δ: Gel fraction is 70% by mass or more and less than 80%.
X: The gel fraction is less than 70% by mass, or the curing does not proceed sufficiently and no film is formed.

[Flexibility evaluation method]
A film was produced by the same method as described in the column of “(2) Evaluation by gel fraction”, and the presence or absence of cracks when the film was bent by hand was evaluated according to the following criteria.

○: No cracking occurs even when bent 90 °.
X: Cracking occurs when bent by 1 to 90 °.
* Since the curing did not proceed sufficiently and the film could not be produced, it could not be evaluated.

(Explanation of abbreviations shown in Table 1 and Table 2)
OXT-221: bis [1-ethyl (3-oxetanyl)] methyl ether.
OXT-121: 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene.
OXT-101: 3-ethyl-3-hydroxymethyloxetane.
OXT-211: 3-ethyl-3- (phenoxymethyl) oxetane.
OXT-212: 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane.
(The above-mentioned, Toa Gosei Co., Ltd., trademark: Aron Oxetane).
UVR-6110: 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate (manufactured by Dow Chemical Japan Co., Ltd., trademark: Cyracure).
CPI-100P: 50% by mass solution of diphenyl-4- (phenylthio) phenylsulfonium hexafluorophosphate in propylene carbonate (manufactured by San Apro Co., Ltd.).

Claims (6)

It contains a urethane prepolymer (A) having at least one alicyclic epoxy group, an oxetane compound (B) having two or more oxetane ring structures, and a photocationic polymerization initiator (C). UV curable resin composition. Furthermore, the ultraviolet curable resin composition of Claim 1 containing an alicyclic epoxy compound (D) other than the said urethane prepolymer (A) which has a 2 or more alicyclic epoxy group. The ultraviolet curable resin composition according to claim 1 or 2, wherein the urethane prepolymer (A) has 2 to 4 alicyclic epoxy groups. The ultraviolet curable resin composition according to any one of claims 1 to 3, wherein the oxetane compound (B) has 2 to 4 oxetane ring structures. The oxetane compound (B) is at least one selected from the group consisting of bis [1-ethyl (3-oxetanyl)] methyl ether and 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene. The ultraviolet curable resin composition according to any one of claims 1 to 3. The mass ratio [(A) / (B)] of the urethane prepolymer (A) and the oxetane compound (B) is in the range of 20/80 to 80/20. The ultraviolet curable resin composition as described.