JP2007119732A - Ultraviolet curable resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet curable resin composition that can be used for sticking base materials together, can show excellent early stage setting and good hardenability, and can form a cured product having good flexibility. <P>SOLUTION: The ultraviolet curable resin composition comprises (A) a urethane prepolymer having more than two hydroxyl groups, (B) an alicyclic epoxy compound having more than two alicyclic epoxy groups, and (C) a cationic photopolymerization initiator. <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 have been made on ultraviolet curable resin compositions that can be cured by irradiating ultraviolet rays, and in recent years, they have been put to practical use in fields such as printing inks, adhesives, and paints. It's getting on.

  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, since the curing reaction of the radical-polymerizable ultraviolet curable resin composition generally proceeds only during a period of irradiation with ultraviolet rays, for example, an adhesive made of the ultraviolet curable resin composition is used for bonding an opaque substrate. It was practically difficult to use. Moreover, the radical polymerizable ultraviolet curable resin composition has a practical problem that it is difficult to cure in the presence of oxygen.

  On the other hand, cationically polymerizable ones are known as ultraviolet curable resin compositions. The curing reaction of the cationic polymerizable ultraviolet curable resin composition is generally not inhibited even in the presence of oxygen, and proceeds even after the irradiation of ultraviolet rays is stopped. Therefore, the ultraviolet curable resin composition is expected to be applied in various fields including, for example, an adhesive that can be used for bonding an opaque base material.

Examples of the cationic polymerizable ultraviolet curable resin composition include a cationic polymerizable compound such as bisphenol A type epoxy resin, a compound having at least two hydroxyl groups in a molecule such as polytetramethylene glycol, and initiation of photo cationic polymerization. An adhesive containing an agent is known (for example, see Patent Document 1).
However, when the application surface of the adhesive is irradiated with ultraviolet rays, curing of the coated surface proceeds even immediately after irradiation, and it may be difficult to bond various substrates to the coated surface.

  On the other hand, as the cationic polymerizable ultraviolet curable resin composition, use of a urethane resin in addition to those mainly composed of a polyester polyol or a polyether polyol as described in the literature 1 has been studied. Urethane resins are generally excellent in properties such as adhesion to a substrate and flexibility. Therefore, if the urethane resin can be cured by UV irradiation, it is UV cured as a high value-added product, particularly in the field of adhesives and paints that require excellent adhesion to the substrate and flexibility. It becomes possible to provide possible adhesives and paints.

  Examples of such urethane resin-based cationically polymerizable ultraviolet curable resin compositions include resins containing an alicyclic epoxy group-containing urethane resin, a cationically polymerizable substance and / or (meth) acrylate, and a photopolymerization initiator. It is known that the composition is excellent in curability and can form a cured product excellent in glossiness and adhesion to a substrate (for example, see Patent Document 2).

  Compared with the resin composition described in the document 1, the resin composition described in the document 2 is less solid after application of ultraviolet rays. It can be used for matching. However, since the resin composition does not have sufficient initial setability immediately after irradiation with ultraviolet rays (a property that the substrates are not easily peeled off when the substrates are bonded), it is difficult to use, for example, an adhesive. Met.

  The urethane resin-based cationic polymerizable ultraviolet curable resin composition includes an aromatic onium salt, a urethane-based polymer, and a cationic polymerizable compound, and is a photosensitive resin that develops color in response to ultraviolet light A composition is known (for example, refer to Patent Document 3).

  However, even if the photosensitive resin composition described in Document 3 is irradiated with ultraviolet rays, curing cannot proceed to a practically sufficient level, and it is practically sufficient in terms of initial setting properties and curability. I couldn't say anything.

JP-A-10-330717 Japanese Patent Laid-Open No. 9-87357 JP-A-11-209603

  The problem to be solved by the present invention is a curing that can be used for bonding substrates, can exhibit excellent initial setting properties, can exhibit good curability, and has good flexibility. It is providing the ultraviolet curable resin composition which can form a thing.

The inventors of the present invention have made a study focusing on the fact that when the progress of the curing reaction of the resin composition is slow, the curing reaction can be generally promoted by heating the resin composition for a certain period of time.
Specifically, after irradiating the resin compositions described in Documents 1 to 3 with ultraviolet rays and then heating for a certain period of time, it was considered that curing could be advanced. Curing could not proceed to the level required for practical use, and good initial setting properties and curability could not be expressed.

  The present inventors have further studied and are generally known as functional groups contributing to cationic polymerization, for example, a hydroxyl group, a glycidyl group, that is, an epoxy group having no alicyclic structure, or an alicyclic group. A urethane prepolymer having an epoxy group, an oxetane ring structure, etc. and a combination of various cationic polymerizable compounds, a urethane prepolymer having two or more hydroxyl groups, and an alicyclic ring having two or more alicyclic epoxy groups According to the ultraviolet curable resin composition containing the formula epoxy compound and the cationic photopolymerization initiator, for example, it is possible to bond an opaque base material, and an excellent initial setting property is obtained by heating for a certain time after irradiation. It has been found that a cured product having good flexibility and good flexibility is formed by curing for a certain period of time after heating. .

  That is, the present invention contains a urethane prepolymer (A) having two or more hydroxyl groups, an alicyclic epoxy compound (B) having two or more alicyclic epoxy groups, and a photocationic polymerization initiator (C). The present invention relates to an ultraviolet curable resin composition.

  The ultraviolet curable resin composition of the present invention can exhibit a practically sufficient level of initial setability and curability by heating for a certain period of time after irradiation with ultraviolet rays. For example, an adhesive for optical components, etc. Various adhesives, adhesives, various sealing agents such as liquid crystal sealants, various resists such as liquid printed wiring board resists and dry film resists, release paper coating agents, optical disk coating agents, can coating agents, It can be used in a wide range of fields such as various coating agents such as surface coating agents for artificial leather and synthetic leather and powder paints, and various ink vehicles such as lithographic inks, screen inks, flexographic inks, gravure inks and jet inks. It is possible and practically extremely useful.

  The present invention comprises as a main component a urethane prepolymer (A) having two or more hydroxyl groups, an alicyclic epoxy compound (B) having two or more alicyclic epoxy groups, and a photocationic polymerization initiator (C). It is an ultraviolet curable resin composition that contains various additives as required.

First, the urethane prepolymer (A) having two or more hydroxyl groups used in the present invention will be described.
The urethane prepolymer (A) having two or more hydroxyl groups used in the present invention is a urethane prepolymer having two or more hydroxyl groups in the molecule.

As said urethane prepolymer (A), it is preferable to use what has 2 or more hydroxyl groups in urethane prepolymer (A), and it is more preferable to use what has 2-3. By using the urethane prepolymer (A) having a hydroxyl group within the above range, the coated surface is hardly solidified immediately after irradiation with ultraviolet rays, and can be used, for example, for bonding an opaque base material. An ultraviolet curable resin composition can be obtained. Moreover, the said ultraviolet curable resin composition can form the hardened | cured material excellent in the sclerosis | hardenability after curing for a fixed time, and excellent in the softness | flexibility and the adhesiveness with respect to a base material.
On the other hand, it is difficult for an ultraviolet curable resin composition using a urethane prepolymer having one hydroxyl group to exhibit a practically sufficient level of curability even after curing for a certain period of time.

  The hydroxyl group present in the urethane prepolymer (A) may be present at the molecular end or side chain of the urethane prepolymer (A), but it improves the curability of the resulting ultraviolet curable resin composition. In consideration, it is preferable to use a urethane prepolymer having a hydroxyl group at the molecular end.

  In addition, what is called a urethane prepolymer generally has a relatively low molecular weight, but those skilled in the art also refer to those having a number average molecular weight of tens of thousands as a urethane prepolymer. Also, urethane prepolymers having a number average molecular weight of tens of thousands can be used. The number average molecular weight measured by size exclusion chromatography of the urethane prepolymer (A) used in the present invention is preferably in the range of 1000 to 100,000, more preferably in the range of 2000 to 50000. By using the urethane prepolymer (A) having a number average molecular weight within the above range, the obtained cured product is excellent in flexibility and has good adhesion to organic materials, inorganic materials, and metal materials. An ultraviolet curable resin composition can be obtained.

  Examples of the urethane prepolymer (A) include, for example, a polyol (a) and a polyisocyanate (b), wherein the equivalent of the hydroxyl group of the polyol (a) is equivalent to the equivalent of the isocyanate group of the polyisocyanate (b). Can be produced by reacting under excessive conditions.

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

  Examples of the polyether polyol that can be used in the polyol (a) include compounds obtained by reacting a reaction initiator having two or more active hydrogen-containing groups in the molecule with an alkylene oxide.

  Examples of the reaction initiator include water, ethylene glycol, propylene glycol, butanediol, glycerin, trimethylolpropane, hexanetriol, triethanolamine, diglycerin, pentaerythritol, methyl glucoside, sorbitol, sucrose, and aliphatic amine compounds. , Aromatic amine compounds, sucrose amine compounds, phosphoric acid, acidic phosphate esters and the like may be used, and these may be used alone or in combination of two or more.

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

  Specific examples of the polyether polyol obtained by the reaction of the reaction initiator having two or more active hydrogen-containing groups in the molecule with an alkylene oxide include, for example, polypropylene glycol, polyethylene glycol, polybutylene glycol, and their co-polymers. Examples include coalescence.

  Moreover, as said polyether polyol, the polytetramethylene glycol obtained by the ring-opening polymerization of tetrahydrofuran other than what was mentioned above can also be used.

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

  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 said cyclic ester compound, (epsilon) -caprolactone, (delta) -valerolactone etc. can be used, for example, These can be used individually or can be used together 2 or more types.

  Examples of other polyols that can be used in the polyol (a) include polymer polyols, modified polyols of polyether polyols, PHD (abbreviation of polyharnsoff dispersion) polyether polyols, urethane-modified polyether polyols, polyether ester copolymer polyols. Etc. can be used. The polymer polyol is a polyether polyol obtained by graft polymerization of a monomer having a vinyl group such as acrylonitrile or styrene monomer in the polyol. The PHD polyether polyol is a polyol in which polyurea produced is stably dispersed by reacting diamine and diisocyanate in polyether.

  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, 1,5-naphthalene diisocyanate, or aroma such as xylylene diisocyanate, tetramethylxylene diisocyanate Diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate having an isocyanate group bonded to the ring via an alkylene group , Alicyclic diisocyanates such as hydrogenated xylylene diisocyanate and norbornene diisocyanate, and aliphatic diisocyanates such as hexamethylene diisocyanate and dimer acid diisocyanate. These can be used alone or in combination of two or more. More preferably, a group diisocyanate is used. By using the aromatic diisocyanate, it is possible to obtain the ultraviolet curable resin composition that is more excellent in curability after curing for a certain time. The reason why the ultraviolet curable resin composition is more excellent in curability after curing for a certain time is because the influence of curing inhibition due to urethane bonds in the urethane prepolymer (A) can be kept relatively low. Presumed.

  The urethane prepolymer (A) can be produced by reacting the polyol (a) and the polyisocyanate (b) by a known and usual method. For example, the polyol (a) is charged into a clean flask, While stirring under a nitrogen atmosphere, the polyisocyanate (b) is charged so that the equivalent of the hydroxyl group of the polyol (a) is excessive with respect to the equivalent of the isocyanate group of the polyisocyanate (b). It can manufacture by the method of making it react with stirring under.

  In the polyol (a) and the polyisocyanate (b), the equivalent ratio of the isocyanate group of the polyisocyanate (b) is 0.2 to 0.9 with respect to 1 equivalent of the hydroxyl group of the polyol (a). It is preferable to react in the range which becomes, and it is more preferable to react in the range of 0.5-0.8. By using the urethane prepolymer obtained by reacting at an equivalent ratio within the above range, the viscosity of the ultraviolet curable resin composition of the present invention can be kept low, and the cured product has good flexibility. Can be obtained.

  In addition, when making the said polyol (a) and the said polyisocyanate (b) react, it is preferable to make them react for about 2 to 15 hours at about 70-100 degreeC.

  Next, the alicyclic epoxy compound (B) having two or more alicyclic epoxy groups used in the present invention will be described.

  The alicyclic epoxy group means that one oxygen atom common to two carbon atoms (usually adjacent to each other) among the carbon atoms forming the alicyclic structure of the alicyclic compound. A bonded epoxy group.

  As said alicyclic epoxy compound (B), it is preferable to use what has 2 or more of alicyclic epoxy groups in a molecule | numerator, and it is more preferable to use what has 2-4. By using the alicyclic epoxy compound (B) having an alicyclic epoxy group within the above range, it becomes possible to obtain an ultraviolet curable resin composition that is more excellent in curability after curing for a certain period of time. Further, since the ultraviolet curable resin composition has a property that the coated surface is not easily solidified immediately after being irradiated with ultraviolet rays, it can be used, for example, for bonding an opaque base material. .

Moreover, as said alicyclic epoxy compound (B), it is more preferable to use what has 3-4 alicyclic epoxy groups in a molecule | numerator. By using the alicyclic epoxy compound (B) having 3 to 4 alicyclic epoxy groups, for example, it can be used for laminating an opaque base material, and after ultraviolet irradiation for a certain period of time. Even without heating, it is possible to obtain an ultraviolet curable resin composition that is more excellent in curability after curing for a certain period of time.
On the other hand, in the ultraviolet curable resin composition containing the alicyclic epoxy compound having one alicyclic epoxy group and the urethane prepolymer (A), it is practically sufficient even after curing for a certain time. It is difficult to develop a level of curability.

  As an alicyclic epoxy compound having two alicyclic epoxy groups, for example, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate represented by the following general formula (1) (wherein a is 0), its caprolactone-modified product (wherein a is a compound of 1), its trimethylcaprolactone-modified product (Structural Formula (2) and Structural Formula (3)), and its valerolactone-modified product (Structural Formula) (4) and structural formula (5)) and compounds represented by structural formula (6) can be used.

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

  Examples of the 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate represented by the general formula (1) and its caprolactone-modified product include, for example, Celoxide 2021, Celoxide 2021A, Celoxide 2021P, Celoxide 2080, Celoxide 2081, Commercially available products such as Celoxide 2083, Celoxide 2085 (manufactured by Daicel Chemical Industries, Ltd.), Cyracure UVR-6105, Cyracure UVR-6107, Cyracure UVR-6110 (above, Dow Chemical Japan Co., Ltd.) are used. be able to.

In addition, as the adipic ester-based alicyclic epoxy compound represented by the general formula (6), for example, commercially available products such as Cyracure UVR-6128 (above, manufactured by Dow Chemical Japan Co., Ltd.) may be used. it can.

  Moreover, as an alicyclic epoxy compound which has three alicyclic epoxy groups, the compound shown by following General formula (7) can be used.

  In general formula (7), b and c are each independently 0 or 1, and they may be the same or different.

  As the alicyclic epoxy compound represented by the general formula (7), for example, commercially available products such as Epolide GT301 and Epolide GT302 (manufactured by Daicel Chemical Industries, Ltd.) can be used.

  Moreover, as an alicyclic epoxy compound which has four alicyclic epoxy groups, the compound shown, for example by following General formula (8) can be used.

  In the general formula (8), d to g each independently represent 0 or 1, and they may be the same or different.

  As the alicyclic epoxy compound represented by the general formula (8), for example, commercially available products such as Epolide GT401, Epolide GT403 (manufactured by Daicel Chemical Industries, Ltd.) can be used.

Next, the photocationic polymerization initiator (C) used in the present invention will be described.
The photocationic polymerization initiator (C) used in the present invention comprises the urethane prepolymer (A) having the hydroxyl group and the alicyclic epoxy group when the ultraviolet curable resin composition of the present invention is irradiated with ultraviolet rays. Cationic polymerization of the alicyclic epoxy compound (B) can be started.

As the photocationic polymerization initiator (C), for example, the cation moiety may be aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium, thianthrhenium, thioxanthonium, (2,4-cyclopentadiene- 1-yl) [(1-methylethyl) benzene] -Fe cation, and the anion moiety is BF ₄ −, PF ₆ −, SbF ₆ −, [BX ₄ ] ⁻ (where X is at least two or more An onium salt composed of a phenyl group substituted with a fluorine or trifluoromethyl 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.

  Moreover, S-biphenyl 2-isopropyl thioxanthonium hexafluorophosphate etc. can be used as said thioxanthonium salt.

  (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, CPI-110P (manufactured by San Apro Co., Ltd.), Syracure photocuring initiator UVI-6990, and Syracure photocuring initiator UVI. -6992, Cyracure photocuring initiator UVI-6976 (above, manufactured by Dow Chemical Japan), Adekaoptomer SP-150, Adekaoptomer SP-170 (above, Asahi Denka Kogyo Co., Ltd.), FC -508, FC-512 (manufactured by 3M), CI-5102, CI-2855 (manufactured by Nippon Soda Co., Ltd.), Sun-Aid SI-60L, Sun-Aid SI-80L, Sun-Aid SI-100L, Sun-Aid SI- 110L, Sun-Aid SI-180L, Sun-Aid SI-110, Sun-Aid SI-180 Sanshin Chemical Industry Co., Ltd.), Esacure 1064, Esacure 1187 (above, manufactured by Lamberti Co., Ltd.), Omnicat 550 (produced by IG Resin Co., Ltd.), Irgacure 250 (produced by Ciba Specialty Chemicals Co., Ltd.), Rhodosil Photoinitiator 2074 (RHODORSIL PHOTOINITIATOR 2074 manufactured by Rhodia Japan Co., Ltd.) can be used.

  In addition, the ultraviolet curable resin composition of the present invention includes two or more oxetanes in addition to the urethane prepolymer (A), the alicyclic epoxy compound (B), and the photocationic polymerization initiator (C). It is preferable to use the oxetane compound (D) having a ring structure in combination because adhesion to a base material, which is an important characteristic as an adhesive, can be improved.

  The oxetane compound (D) having two or more oxetane ring structures has two or more oxetane ring structures represented by the following structural formula (9) in the molecule, and the photocationic polymerization initiator (C) The ring is opened by irradiation with ultraviolet rays in the presence of, thereby allowing the polymerization reaction to proceed.

  As said oxetane compound (D), it is preferable to have 2 or more of the said oxetane ring structure in a molecule | numerator, and it is more preferable to have 2-4. By using the oxetane compound (D) having an oxetane ring structure within the above-mentioned range, it is possible to form a cured product that is excellent in curability after curing for a certain period of time and is excellent in flexibility and adhesion to a substrate. A curable resin composition can be obtained. In addition, since the ultraviolet curable resin composition can maintain the property that the coated surface is not easily solid even when irradiated with ultraviolet rays, it can be used, for example, for bonding an opaque base material. .

  As the oxetane compound (D) having two or more oxetane ring structures, for example, compounds represented by the following general formulas (10) and (11) can be used alone or in combination of two or more.

In the general formulas (10) and (11), 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 (10), 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 (12) and (13).

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. An alkylene group of ˜15 is preferred. 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 (12), 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 (13), 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 (14).

  In the general formula (14), h represents an integer of 1 to 6, and i represents an integer of 1 to 15.

  As said general formula (14), it is preferable that i is an integer of 1-3.

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

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 alicyclic epoxy compound (B), and, if necessary, the oxetane compound (D) using a closed planetary mixer. 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 alicyclic epoxy compound (B) in the ultraviolet curable resin composition of the present invention is 30/70 to 70 /. A range of 30 is preferable, and a range of 40/60 to 60/40 is more preferable. By using an ultraviolet curable resin composition having a mass ratio in the above range, the coated surface is unlikely to become solid even when irradiated with ultraviolet rays, so it can be used, for example, for bonding an opaque substrate. In addition, it is possible to form a cured product that is excellent in curability after curing for a certain period of time and has good flexibility.

  Moreover, when using together the oxetane compound (D) which has a 2 or more oxetane ring structure, the mass ratio [(B) / (D of the said alicyclic epoxy compound (B) and the said oxetane compound (D). )] Is preferably in the range of 50/50 to 90/10, and more preferably in the range of 50/50 to 80/20. By using an ultraviolet curable resin composition having a mass ratio in the above range, while maintaining good reactivity of the copolymerization reaction between the urethane prepolymer (A) and the alicyclic epoxy compound (B), Since the reactivity of the copolymerization reaction between the alicyclic epoxy compound (B) and the oxetane compound (D) can be improved, the curability of the ultraviolet curable resin composition can be further improved. It becomes possible, and the flexibility of the obtained cured product and the adhesion to the substrate can be further improved.

  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 photocationic polymerization initiator (C) in the above range has good curability, and the amount of the acid remaining in the obtained cured product is almost negligible. 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, for example, surface-treated calcium carbonate, fine powder silica, bentonite, zeolite, and the like can be used.

The ultraviolet curable resin composition of the present invention can be applied to various substrates to a thickness of 10 to 500 μm using, for example, a roll coater. As an ultraviolet irradiation amount which can be irradiated to the coated surface, 50 to 5000 mJ / cm ² is preferable, and 100 to 3000 mJ / cm ² is more preferable. The ultraviolet curable resin composition of the present invention is sufficiently cured by heating for a certain period of time even after irradiation with a relatively low level of UV irradiation, which is approximately 100 to 1000 mJ / cm ² as a guide. It is possible.

  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.).

The ultraviolet curable resin composition of the present invention can form a cured coating film by irradiating the application surface with ultraviolet rays and then heating for a certain time.
As the heating condition, it is preferable to heat at a temperature of approximately 50 to 150 ° C. for 1 minute or longer, and more preferable to heat at a temperature of 60 to 120 ° C. for 1 to 10 minutes.

  The ultraviolet curable resin composition of this invention can be used as an adhesive agent which can be used for bonding of various base materials.

Specifically, as a method of adhering a base material using the ultraviolet curable resin composition of the present invention, the ultraviolet curable resin composition is applied to the surface of the base material with a thickness of 10 to 500 μm using a roll coater or the like. A first step of initiating an ultraviolet curing reaction of the ultraviolet curable resin composition applied to the surface of the substrate by irradiating with an ultraviolet ray having an irradiation amount of approximately 100 to 1000 mJ / cm ² ; Another substrate is bonded to the coated surface, and the ultraviolet curable resin composition coated on the coated surface is cured by heating at a temperature of approximately 50 to 150 ° C. for 1 minute or more, and the substrates are bonded to each other. It consists of a second step. Since the coating surface after irradiation with ultraviolet rays in the first step is unlikely to be solid, the substrate can be bonded in the second step.

  As the substrate, for example, paper, wood, plastic, glass, metal or the like can be used. Specific examples of the plastic include polyvinyl chloride resin. The substrate may be either transparent or opaque, but if the ultraviolet curable resin composition in the present invention is used, it is possible to bond the opaque substrates together.

  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 a hydroxyl group)
346 parts by mass of polypropylene glycol (hydroxyl equivalent = 1000), 432 parts by mass of polypropylene glycol (hydroxyl equivalent = 200), polyester obtained by reacting neopentyl glycol, 1,6-hexanediol and adipic acid in a clean flask While charging 86 parts by mass of a diol (hydroxyl equivalent = 1000) and stirring in a nitrogen atmosphere, 136 parts by mass of an 80:20 (mass ratio) mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate was added. Charged (isocyanate group equivalent / hydroxyl group equivalent = 0.60) and reacted at 90 ° C. for 3 hours with stirring under a nitrogen atmosphere to obtain a urethane prepolymer (I) having a hydroxyl group at the molecular end. The number average molecular weight measured by size exclusion chromatography (SEC) of the obtained urethane prepolymer (I) was 3000.

[Synthesis Example 2] (Synthesis example of urethane prepolymer (II) having a hydroxyl group)
A clean flask was charged with 855 parts by mass of polypropylene glycol (hydroxyl equivalent = 1000) and 95 parts by mass of polyester diol (hydroxyl equivalent = 1000) obtained by reacting neopentyl glycol, 1,6-hexanediol and adipic acid. While stirring in a nitrogen atmosphere, 50 parts by mass of an 80:20 (mass ratio) mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate was charged (isocyanate group equivalent / hydroxyl group equivalent = 0.60. ), The mixture was reacted at 90 ° C. for 3 hours with stirring in a nitrogen atmosphere to obtain a urethane prepolymer (II) having a hydroxyl group at the molecular end. The number average molecular weight measured by size exclusion chromatography (SEC) of the obtained urethane prepolymer (II) was 6000.

[Synthesis Example 3] (Synthesis Example of Urethane Prepolymer (III) Having a Hydroxyl Group)
A clean flask was charged with 432 parts by mass of polypropylene glycol (hydroxyl equivalent = 200) and 432 parts by mass of polyester diol (hydroxyl equivalent = 1000) obtained by reacting neopentyl glycol, 1,6-hexanediol and adipic acid. While stirring in a nitrogen atmosphere, 136 parts by mass of an 80:20 (mass ratio) mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate was charged (isocyanate group equivalent / hydroxyl group equivalent = 0.60. ), The mixture was reacted at 90 ° C. for 3 hours with stirring in a nitrogen atmosphere to obtain a urethane prepolymer (III) having a hydroxyl group at the molecular end. The number average molecular weight measured by size exclusion chromatography (SEC) of the obtained urethane prepolymer (III) was 3000.

[Synthesis Example 4] (Synthesis Example of Urethane Prepolymer (IV) Having a Hydroxyl Group)
A clean flask was charged with 950 parts by mass of a polyester diol (hydroxyl equivalent = 1000) obtained by reacting neopentyl glycol, 1,6-hexanediol, and adipic acid. -Charge 50 parts by mass of a 80:20 (mass ratio) mixture of tolylene diisocyanate and 2,6-tolylene diisocyanate (isocyanate group equivalent / hydroxyl group equivalent = 0.60) and stir in a nitrogen atmosphere at 90 ° C. To obtain a urethane prepolymer (IV) having a hydroxyl group at the molecular end. The number average molecular weight measured by size exclusion chromatography (SEC) of the obtained urethane prepolymer (IV) was 6000.

[Synthesis Example 5] (Synthesis example of urethane prepolymer (V) having an alicyclic epoxy group)
A clean flask was charged with 601 parts by weight of polypropylene glycol (hydroxyl equivalent = 1000) and 227 parts by weight of 4,4′-diphenylmethane diisocyanate while stirring in a nitrogen atmosphere (isocyanate group equivalent / hydroxyl equivalent = 3.00). The contents were reacted at 90 ° C. for 3 hours while stirring under a nitrogen atmosphere.

  Next, 172 parts by mass of a compound of the following structural formula (15) (3,4-epoxycyclohexylmethanol, manufactured by Daicel Chemical Industries, Ltd.) was charged with further stirring (isocyanate group equivalent / hydroxyl group equivalent = 0.90). The contents were reacted at 90 ° C. for 3 hours with stirring under a nitrogen atmosphere to obtain a urethane prepolymer (V) having an alicyclic epoxy group. The number average molecular weight measured by size exclusion chromatography (SEC) of the obtained urethane prepolymer (V) was 2000.

[Example 1]
In a closed planetary mixer, 50 parts by mass of the urethane prepolymer (I) and Cyracure UVR-6110 (3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, manufactured by Dow Chemical Japan Co., Ltd.) ) 50 parts by mass were charged and mixed by stirring until uniform. Next, 5 parts by mass of CPI-100P (diphenyl-4- (phenylthio) phenylsulfonium hexafluorophosphate in 50% by mass of propylene carbonate solution: manufactured by San Apro Co., Ltd.) was mixed and stirred, so that the ultraviolet curable resin of the present invention was mixed. A composition was obtained.

[Examples 2 to 9, Comparative Examples 1 to 7]
The compounds and blending ratios used in place of the urethane prepolymer (I), Syracure UVR-6110, and CPI-100P are in accordance with the descriptions in Tables 1 and 2; A curable resin composition was prepared.

The bonding properties, initial setting properties, curability and flexibility of the ultraviolet curable resin compositions of Examples 1 to 9 and Comparative Examples 1 to 7 were evaluated by the methods described below.
About the ultraviolet curable resin composition of Examples 1-9, it evaluated by the method described below also about base-material adhesiveness.

[Evaluation method for bonding properties]
Evaluation by finger touch and paper bonding Using a bar coater, the ultraviolet curable resin composition was applied to a polypropylene plate to a thickness of 100 μm. Conveyor type UV irradiation device CSOT-40 (manufactured by Nippon Battery Co., Ltd., using a high-pressure mercury lamp, strength 120 W / cm, set to have an UV irradiation amount of 145 mJ / cm ² every time it passes through the device. By using a conveyor speed of 10 m / min), the coated surface of the ultraviolet curable resin composition was irradiated with ultraviolet rays by passing the polypropylene plate coated with the ultraviolet curable resin composition once. The coated surface after irradiation was pressed with a finger to determine whether the coated surface was liquid or cured and solid. Further, the paper was bonded to the coated surface, and the paper was peeled immediately after being pressed with a rubber roll, and the state of the paper bonded surface at that time was visually determined. The evaluation of the bonding property was performed based on the following criteria. 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).

◯: The coated surface is liquid and the ultraviolet curable resin composition is adhered to the paper side.
X: The coated surface is solid and the ultraviolet curable resin composition does not adhere to the paper side.

[Evaluation method for initial setting]
Evaluation by Gel Fraction Using a bar coater, the ultraviolet curable resin composition was applied on a polypropylene plate to a thickness of 100 μm. Conveyor type UV irradiation device CSOT-40 (manufactured by Nippon Battery Co., Ltd., using a high-pressure mercury lamp, strength 120 W / cm, set to have an UV irradiation amount of 145 mJ / cm ² every time it passes through the device. Using a conveyor speed of 10 m / min, the coated surface of the ultraviolet curable resin composition was irradiated with ultraviolet rays by passing the polypropylene plate coated with the ultraviolet curable resin composition five times.
After the irradiation, immediately after heating for 3 minutes at 85 ° C., the film obtained by curing the ultraviolet curable resin composition from the polypropylene plate was peeled off. The obtained film was immersed in ethyl acetate at 50 ° C. for 24 hours, and then dried at 107 ° C. for 1 hour. The gel fraction (% by mass) was calculated based on the mass of the film before and after immersion and the following formula.

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

  A gel fraction immediately after the heating of 40% by mass or more can be said to be excellent in initial setting properties, and is practically preferable.

[Evaluation method of curability]
Evaluation by Gel Fraction Using a bar coater, the ultraviolet curable resin composition was applied on a polypropylene plate to a thickness of 100 μm. Conveyor type UV irradiation device CSOT-40 (manufactured by Nippon Battery Co., Ltd., using a high-pressure mercury lamp, strength 120 W / cm, set to have an UV irradiation amount of 145 mJ / cm ² every time it passes through the device. Using a conveyor speed of 10 m / min, the polypropylene plate coated with the ultraviolet curable resin composition was passed five times, and the coated surface of the ultraviolet curable resin composition was irradiated with ultraviolet rays.
After irradiation, the mixture was heated for 3 minutes under the condition of 85 ° C., and then cured for 7 days in an atmosphere of 23 ° C. and 50% relative humidity. After curing, the film obtained by curing the ultraviolet curable resin composition from the polypropylene plate was peeled off. The obtained film was immersed in ethyl acetate at 50 ° C. for 24 hours, and then dried at 107 ° C. for 1 hour. The gel fraction (% by mass) was calculated based on the mass of the film before and after immersion and the following formula.

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

  A gel fraction having a gel fraction of 60% by mass or more after curing for 7 days after the heating can be said to be excellent in curability and is preferable in practical use.

[Evaluation method of substrate adhesion]
Evaluation by Cross Cut Test Using a bar coater, the ultraviolet curable resin compositions of Examples 1 to 9 were applied to a thickness of 100 μm on a hard vinyl chloride plate (hard PVC). Conveyor type UV irradiation device CSOT-40 (manufactured by Nippon Battery Co., Ltd., using a high-pressure mercury lamp, strength 120 W / cm, set to have an UV irradiation amount of 145 mJ / cm ² every time it passes through the device. Using a conveyor speed of 10 m / min, the coated surface of the ultraviolet curable resin composition was irradiated with ultraviolet rays by passing the hard vinyl chloride plate coated with the ultraviolet curable resin composition five times.
After irradiation, it was heated for 3 minutes under the condition of 85 ° C., and cured for 7 days in an atmosphere of 23 ° C. and 50% relative humidity.
The substrate adhesion of the obtained coating film was evaluated by a cross cut test in accordance with JIS K5400.

Evaluation of substrate adhesion ◎ ... 0-25% of total area of coated surface
○ ... 26-50% of the total area of the coated surface
△ ... peeling is 51 to 75% of the total area of the coated surface
X ... 76-100% of the total area of the coated surface

[Flexibility evaluation method]
In the above-mentioned “curability evaluation method”, a film was prepared by the same method as described in the column “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 hardening did not fully advance and a film could not be produced, it was not evaluated.

(Explanation of abbreviations shown in Table 1 and Table 2)
L220AL: Liquid polycaprolactone diol, hydroxyl equivalent 1000 (Daicel Chemical Industries, Trademark: Plaxel).
UVR-6110: 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate (manufactured by Dow Chemical Japan Co., Ltd., trademark: Cyracure).
GT-401: An alicyclic epoxy compound having four alicyclic epoxy groups with d + e + f + g = 1 in the general formula (8) (trade name: Epolide, manufactured by Daicel Chemical Industries, Ltd.).
EX-214L: 1,4-butanediol diglycidyl ether (manufactured by Nagase ChemteX Corporation, trademark: Denacol)
RXE-21: Hydrogenated bisphenol A type liquid epoxy resin (trade name: Epicoat manufactured by Japan Epoxy Resin Co., Ltd.)
OXT-221: Bis [1-ethyl (3-oxetanyl)] methyl ether (trade name: Aron Oxetane, manufactured by Toagosei Co., Ltd.).
CPI-100P: 50% by mass solution of diphenyl-4- (phenylthio) phenylsulfonium hexafluorophosphate in propylene carbonate (manufactured by San Apro Co., Ltd.).
Rigid PVC: Rigid vinyl chloride plate

Claims (7)

It contains a urethane prepolymer (A) having two or more hydroxyl groups, an alicyclic epoxy compound (B) having two or more alicyclic epoxy groups, and a photocationic polymerization initiator (C). UV curable resin composition. The ultraviolet curable resin composition according to claim 1, wherein the urethane prepolymer (A) has 2 to 3 hydroxyl groups. The ultraviolet curable resin composition according to claim 1 or 2, wherein the alicyclic epoxy compound (B) has 2 to 4 alicyclic epoxy groups. Furthermore, the ultraviolet curable resin composition in any one of Claims 1-3 containing the oxetane compound (D) which has a 2 or more oxetane ring structure. The mass ratio [(A) / (B)] of the urethane prepolymer (A) and the alicyclic epoxy compound (B) is in the range of 30/70 to 70/30. The ultraviolet curable resin composition in any one. The ultraviolet ray according to claim 4, wherein a mass ratio [(B) / (D)] of the alicyclic epoxy compound (B) and the oxetane compound (D) is in a range of 50/50 to 90/10. Curable resin composition. An adhesive comprising the ultraviolet curable resin composition according to any one of claims 1 to 6.