JP2008291126A - Photocurable composition and gasket for electronic component using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a photocurable composition that improves reworkability as a sealing material while having a proper hardness and a gasket for electronic components using the same. <P>SOLUTION: In the photocurable composition comprising a photocurable liquid resin, a (meth)acrylate monomer and a photopolymerization initiator, the photocurable liquid resin comprises a hydrogenated conjugated diene-aromatic vinyl copolymer containing a photocurable functional group and the photopolymerization initiator contains at least an aminoacetophenone-based photopolymerization initiator. The gasket for electronic components uses the photocurable composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photocurable composition containing a photocurable liquid resin, a (meth) acrylate monomer and a photopolymerization initiator, and a gasket for electronic parts using the same.

In recent years, various photocurable resins have been developed for sealing materials and adhesives.
For example, Patent Document 1 discloses a polyether polyol-based photocurable resin for surface processing of woodwork products such as woodworking plywood, furniture, and musical instruments. However, since polyether polyol has high hydrophilicity and high water vapor permeability, it is unsuitable for use in sealing materials and gasket materials that require water vapor barrier properties.
Patent Document 2 discloses a polyester polyol-based photocurable resin composition for wood coatings. However, polyester polyols are unsuitable for use in sealing materials, particularly gasket materials, which are exposed to high temperature and high humidity environments because the polyester main chain undergoes hydrolytic degradation under high temperature and high humidity environments.
By the way, in the final inspection, when a defective product occurs in the final inspection, it is necessary to perform so-called rework in which the defective component is replaced by removing the cover of the component sealed with a gasket or the like. At this time, if the sealing material such as the gasket is torn off, the cover cannot be reused. On the other hand, curability is also required for maintaining a sealing property by holding a cover as a sealing material such as a gasket.
As examples of improving the water vapor permeability (low moisture permeability) or adhesiveness described above, Patent Documents 3 to 6 include photocurable hydrogenated or non-hydrogenated liquid polyisoprene or photocurable hydrogenated or non-aqueous. Although liquid polybutadiene has been proposed, the fact is that it has not been developed from the viewpoint of achieving both reworkability and curability.

Japanese Patent Laid-Open No. 5-202163 JP 2000-219714 A JP 2002-371101 A JP 2005-60465 A JP 2006-298964 A JP 2007-39587 A Japanese Patent Publication No. 1-53681

  The present invention provides a photocurable composition capable of improving reworkability as a sealing material while having an appropriate hardness under such circumstances, and an electronic component gasket using the same. It is for the purpose.

As a result of intensive studies to achieve the above object, the present inventors have made reworkability by reducing the tackiness of the photocurable composition after curing and reducing the compression set. It has been found that it can be improved. The present invention has been completed based on such findings.
That is, the present invention relates to a hydrogenated conjugated diene in which a photocurable liquid resin contains a photocurable functional group in a photocurable composition containing a photocurable liquid resin, a (meth) acrylate monomer, and a photopolymerization initiator. A photocurable composition comprising an aromatic vinyl copolymer, wherein the photopolymerization initiator contains at least an aminoacetophenone photopolymerization initiator, and a gasket for an electronic component using the same is there.

  According to the present invention, it is possible to provide a photocurable composition that can improve reworkability as a sealing material while having an appropriate hardness, and further, it is possible to provide a gasket for electronic parts using the same. .

The present invention relates to a photocurable composition containing a photocurable liquid resin, a (meth) acrylate monomer and a photopolymerization initiator, wherein the photocurable liquid resin contains a photocurable functional group. -It consists of an aromatic vinyl copolymer, and the photopolymerization initiator contains at least an aminoacetophenone photopolymerization initiator.
Here, among the monomers constituting the hydrogenated conjugated diene-aromatic vinyl copolymer, examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3. -Dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene and the like. Among these, 1,3-butadiene and / or isoprene are preferable from the viewpoint of securing rubber elasticity after curing, and 1,3-butadiene is particularly preferable. These may be used alone or in combination of two or more.

  Among the monomers constituting the hydrogenated conjugated diene-aromatic vinyl copolymer, the aromatic vinyl monomer includes styrene, α-methyl styrene or paramethyl styrene after rubber is cured. Of these, styrene is particularly preferable. These may be used alone or in combination of two or more.

By using a hydrogenated conjugated diene-aromatic vinyl copolymer containing a photocurable functional group as a photocurable liquid resin, it is cured while having an appropriate hardness in combination with an appropriate photopolymerization initiator. The adhesiveness (tackiness) of the later photocurable composition can be reduced, and the compression set can be reduced, and the reworkability as a sealing material can be improved.
By the way, siloxane present in the air dissolves and diffuses in the gasket and permeates into the inside of the hard disk (hereinafter referred to as HDD), thereby generating SiO ₂ fine crystals on the surface of the electronic component, particularly the HDD. It may adversely affect the quality of electronic components and may cause damage to HDDs in severe cases. In contrast, the photocurable hydrogenated conjugated diene-aromatic vinyl copolymer dissolves the siloxane present in the air as compared with the photocurable hydrogenated liquid polyisoprene or the photocurable hydrogenated liquid polybutadiene. Therefore, HDD damage due to siloxane dissolution can be prevented as a gasket for HDD, which is preferable.

  In the present invention, the photocurable functional group contained in the hydrogenated conjugated diene-aromatic vinyl copolymer is preferably a photocurable unsaturated hydrocarbon group, and the photocurable unsaturated hydrocarbon group is (meta It is particularly preferred that it is an acryloyl group. Here, the (meth) acryloyl group refers to an acryloyl group or a methacryloyl group.

Examples of the aminoacetophenone photopolymerization initiator include 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one [Ciba Specialty Chemicals Co., Ltd., trade name: Irgacure 907], 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone [Ciba Specialty Chemicals Co., Ltd., trade name: Irgacure 369], 2- (dimethylamino)- 2-[(4-Methylphenyl) methyl] -1- (4-morpholinophenyl) -1-butanone [Ciba Specialty Chemicals Co., Ltd., trade name: Irgacure 379] and the like.
The aminoacetophenone photopolymerization initiator has a high reaction activity and is less susceptible to oxygen inhibition of the surface of the photocurable composition due to the presence of nitrogen atoms. The tackiness of the photocurable composition can be reduced, and the compression set can be reduced. Thereby, the photocurable composition of this invention can improve the rework property as a sealing material.
The amount of the photopolymerization initiator blended in the photocurable composition of the present invention is preferably 0.1 to 6 parts by mass with respect to 100 parts by mass in total of the photocurable liquid resin and the (meth) acrylate monomer. More preferably, it is 0.5-5 mass parts, More preferably, it is 1-4 mass parts.

In the present invention, the above-mentioned aminoacetophenone photopolymerization initiator may be used in combination with other photopolymerization initiators as desired.
Other photopolymerization initiators include benzoin derivatives and benzyl ketals [for example, Ciba Specialty Chemicals, trade name: Irgacure 651], α-hydroxyacetophenones [for example, Ciba Specialty Chemicals, Inc., trade names: Darocur 1173, Irgacure 184, Irgacure 127, Irgacure 2959], acylphosphine oxides [for example, Ciba Specialty Chemicals, Inc., trade names: Irgacure 819, Irgacure TPO] and the like, and examples of the hydrogen abstraction type include a combination of benzophenones and amine, a combination of thioxanthone and amine, and the like.

  In addition, as oligomerized α-hydroxyacetophenone, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone] [for example, Lamberti S. et al. p. A product, trade name: ESACURE KIP150, etc.], and acrylated benzophenones such as acrylated benzophenone [eg, Daicel UCB Co., Ltd., trade name: Ebecryl P136, etc.], imide acrylate, and the like.

  Further, benzoyl methyl ether, benzoyl ethyl ether, benzoyl butyl ether, benzoyl isopropyl ether, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, 2-hydroxy-2-methyl- [4- (1-methylvinyl) phenyl ] Propanol oligomer, 2-hydroxy-2-methyl- [4- (1-methylvinyl) phenyl] propanol oligomer and 2-hydroxy-2-methyl-1-phenyl-1-propanone, isopropylthioxanthone, o-benzoyl Methyl benzoate and [4- (methylphenylthio) phenyl] phenylmethane can also be used in combination.

The (meth) acrylate monomer used in the photocurable composition of the present invention not only reduces the viscosity of the photocurable composition before curing, but also improves various physical properties after curing. That is, it is possible to improve adhesive strength and low moisture permeability, adjust hardness and tackiness, and improve Eb (elongation) and Tb (breaking strength). The molecular weight of the (meth) acrylate monomer is preferably less than 1,000, and more preferably 150 to 600.
Specific examples of (meth) acrylate monomers include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, diethylene glycol monoethyl ether (meth) ) Acrylate, dimethylaminoethyl (meth) acrylate, dimethylol dicyclopentane (meth) acrylate, dipropylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, ethoxylated phenyl (meth) acrylate, ethyl (meth) acrylate, Isoamyl (meth) acrylate, isobornyl (meth) acrylate, isobutyl (meth) acrylate, isodecyl (meth) acrylate, isooctyl (Meth) acrylate, isostearyl (meth) acrylate, isomyristyl (meth) acrylate, lauroxypolyethylene glycol (meth) acrylate, lauryl (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxytripylene glycol (meta ) Acrylate, methoxypolyethylene glycol (meth) acrylate, methoxytriethylene glycol acrylate and the like.
In addition, (meth) acrylate means an acrylate or a methacrylate.
Among these, in the present invention, isobornyl acrylate, dicyclopentanyl acrylate and dicyclopentenyl acrylate are preferable.

  The blending amount of the (meth) acrylate monomer is 100 parts by mass of the photocurable liquid resin and the (meth) acrylate monomer, and the ratio of the parts by mass (photocurable liquid resin / (meth) acrylate monomer) is , (20/80) to (100/0) are preferable, and (30/70) to (90/10) are more preferable. When the (meth) acrylate monomer is 10 parts by mass or more, the effect of reducing the viscosity of the photocurable composition can be enjoyed, and extrusion, discharge and the like are facilitated, and it is easy to form a sealing material. Moreover, if it is 70 mass parts or less, the viscosity of this composition will not become low too much, and it will become difficult to flow down the sealing material etc. immediately after formation. Furthermore, since the adhesive strength and elasticity of the cured sealing material and the like are ensured, the airtightness is not easily lost.

The photocurable composition of the present invention may further contain a thixotropic agent as desired. By including a thixotropic agent, the tackiness (tackiness) of the photocurable composition can be further reduced.
There are organic and inorganic thixotropic agents. Examples of the organic thixotropic agent include hydrogenated castor oil, amide, polyethylene oxide, vegetable oil polymerized oil and surfactant, or a composite system using two or more of these in combination. Hydrogenated castor oil thixotropic agent is a wax-like hardened by adding hydrogen to castor oil (non-drying oil whose main component is ricinoleic acid). Amide type thixotropic agent is composed of vegetable oil fatty acid and amine. It is an amide wax that is a synthesized compound having an amide bond. Specifically, hydrogenated castor oil [for example, manufactured by Rockwood Additives Co., Ltd., trade name: ADVITOLL100, manufactured by Enomoto Kasei Co., Ltd., trade name: Disparon 305, etc.] and amide wax [for example, Enomoto Kasei Co., Ltd.] Manufactured, trade name: Disparon 6500, etc.].
Examples of the inorganic thixotropic agent include silica, bentonite, organic coupling agent-treated silica, organic coupling agent-treated bentonite, and ultrafine surface-treated calcium carbonate, or a composite system in which two or more of these are used in combination. . Specifically, a silica fine powder pulverized by a dry method [for example, Nippon Aerosil Co., Ltd., trade name: Aerosil 300, etc.], a fine powder obtained by modifying this silica fine powder with trimethyldisilazane [for example, Nippon Aerosil Product name: Aerosil RX300, etc.] and fine powder obtained by modifying the above silica fine powder with polydimethylsiloxane [for example, product name: Aerosil RY300, manufactured by Nippon Aerosil Co., Ltd.]. The average particle diameter of the inorganic thixotropic agent is preferably 5 to 50 μm and more preferably 5 to 12 μm from the viewpoint of imparting thixotropic properties.
The amount of the thixotropic agent blended in the photocurable composition of the present invention is preferably 0.1 to 10 parts by mass with respect to a total of 100 parts by mass of the photocurable liquid resin and the (meth) acrylate monomer. More preferably, it is 0.5-8 mass parts, More preferably, it is 1-5 mass parts.

The photocurable liquid resin used in the photocurable composition of the present invention is a hydrogenated conjugated diene-aromatic vinyl copolymer containing a photocurable functional group, and is preferably produced as follows. .
(A) In a saturated hydrocarbon solvent, a conjugated diene monomer and an aromatic vinyl monomer are polymerized with a dilithium initiator to obtain a weight average molecular weight of 5,000 to 40,000 and a molecular weight distribution of 3.0 or less. Producing a conjugated diene-aromatic vinyl copolymer having:
(B) reacting the conjugated diene-aromatic vinyl copolymer with an alkylene oxide to produce a conjugated diene-aromatic vinyl copolymer polyol;
(C) hydrogenating the conjugated diene-aromatic vinyl copolymer polyol to produce a hydrogenated conjugated diene-aromatic vinyl copolymer polyol;
(D) A process for producing a photocurable liquid resin comprising the step of reacting the hydrogenated conjugated diene-aromatic vinyl copolymer polyol with a photocurable unsaturated hydrocarbon group-containing compound. .

First, as a first stage (A), a conjugated diene monomer and an aromatic vinyl monomer are polymerized with a dilithium initiator in a saturated hydrocarbon solvent to obtain a conjugated diene-aromatic vinyl copolymer ( Hereinafter, the “copolymer according to the present invention” is sometimes produced. Since the main polymerization is living anionic polymerization, the polymerization can be performed while controlling the molecular weight and molecular weight distribution. The molecular weight can be obtained by polymerizing a polymer having a predetermined molecular weight depending on the amount of the dilithium initiator and the above monomer. Particularly, when the weight average molecular weight is 5,000 or more, a narrow polymer having a molecular weight distribution of 2 or less Easy to get. If desired, anionic polymerization may be carried out in the presence of a randomizer.
Next, as a second step (B), a conjugated diene having hydroxyl groups at both ends is obtained by reacting the copolymer end as a living anion with an alkylene oxide in an equivalent manner in the copolymer according to the present invention. An aromatic vinyl copolymer polyol (hereinafter sometimes referred to as “copolymer polyol according to the present invention”) can be obtained.
Furthermore, as the third step (C), the copolymer polyol according to the present invention having a double bond in the main chain is subjected to a hydrogenation reaction (hereinafter referred to as a hydrogenation reaction), whereby the main chain is unsaturated. Hydrogenated conjugated diene-aromatic vinyl copolymer polyol (hereinafter sometimes referred to as “hydrogenated copolymer polyol according to the present invention”) having no heavy bond or few main chain unsaturated double bonds Obtainable.
As a fourth step (D), the hydrogenated copolymer polyol according to the present invention obtained as described above is reacted with a photocurable unsaturated hydrocarbon group-containing compound to contain a photocurable functional group. A hydrogenated conjugated diene-aromatic vinyl copolymer is obtained.

  The dilithium initiator is not particularly limited, and known ones can be used. For example, Patent Document 7 describes a method for producing a dilithium initiator by reacting a monolithium compound with a disubstituted vinyl or an alkenyl group-containing aromatic hydrocarbon in the presence of a tertiary amine.

  Monolithium compounds used when producing a dilithium initiator include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, tert-octyl lithium, and n-decyl. Examples thereof include lithium, phenyl lithium, 2-naphthyl lithium, 2-butyl-phenyl lithium, 4-phenyl-butyl lithium, cyclohexyl lithium, cyclopentyl lithium, and among these, sec-butyl lithium is preferable.

Examples of the tertiary amine used when producing the dilithium initiator include lower aliphatic amines such as trimethylamine and triethylamine, N, N-diphenylmethylamine, and the like, and triethylamine is particularly preferable.
Examples of the disubstituted vinyl or alkenyl group-containing aromatic hydrocarbon include 1,3- (diisopropenyl) benzene, 1,4- (diisopropenyl) benzene, 1,3-bis (1-ethylethenyl). ) Benzene, 1,4-bis (1-ethylethenyl) benzene and the like are preferred.

  The solvent used in the preparation of the dilithium initiator and the production of the copolymer may be an organic solvent inert to the reaction, and is a hydrocarbon solvent such as an aliphatic, alicyclic, or aromatic hydrocarbon compound. For example, n-butane, l-butane, n-pentane, l-pentane, cis-2-butene, trans-2-butene, l-butene, n-hexane, n-heptane, n-octane, One or two kinds selected from l-octane, methylcyclopentane, cyclopentane, cyclohexane, 1-hexene, 2-hexene, 1-pentene, 2-pentene, benzene, toluene, xylene, ethylbenzene and the like are used. Of these, n-hexane and cyclohexane are usually used.

  Further, examples of the alkylene oxide used in the polyolization reaction that reacts with the terminal which is the living anion of the copolymer according to the present invention to generate a hydroxyl group at both terminals include ethylene oxide, propylene oxide, butylene oxide, and the like. . This polyol reaction is preferably performed immediately after the polymerization reaction.

If the weight average molecular weight of the copolymer polyol according to the present invention obtained by the above polyol reaction is 5,000 or more, the molecular weight between cross-linking points can be increased, and after the photocuring reaction, the elastic modulus is lowered and the elongation is reduced. Since it can be increased, it is preferable as a rubber material. On the other hand, if the weight average molecular weight is 40,000 or less, the polymerization viscosity does not become too high when polymerization is performed with a dilithium catalyst, and it is not necessary to lower the solid content concentration as a polymerization process Therefore, it becomes low cost and preferable.
Moreover, various influences by a low molecular weight component and a high molecular weight component can be suppressed as molecular weight distribution is 3.0 or less. In particular, since the viscosity is greatly affected by the molecular weight, slight fluctuations in the molecular weight cause viscosity variations. In the present invention in which a copolymer having a narrow molecular weight distribution can be synthesized, a copolymer having the same molecular weight can be obtained with good reproducibility, so that an effect of stabilizing the viscosity can be expected. In many cases, the liquid material as in the present invention is applied by a dispenser. In this case, since the variation in the material viscosity causes a variation in the dimension after the application, the stabilization of the viscosity is important, and the molecular weight distribution is 3. It is preferably 0 or less.

The hydrogenation reaction for obtaining the hydrogenated copolymer polyol according to the present invention is carried out by hydrogenating the copolymer polyol according to the present invention in the presence of a hydrogenation catalyst in an organic solvent under hydrogen pressure. . The hydrogenation catalyst used in this hydrogenation reaction is a heterogeneous catalyst such as palladium-carbon, reduced nickel, rhodium, or the like, or an organic nickel compound such as nickel naphthenate or nickel octoate, or cobalt naphthenate or cobalt octoate. A homogeneous catalyst in which an organocobalt compound and an organoaluminum compound such as triethylaluminum and triisobutylaluminum or an organolithium compound such as n-butyllithium and sec-butyllithium are combined can be used. As a cocatalyst, an ether compound such as tetrahydrofuran, ethylene glycol dimethyl ether, or diethylene glycol dimethyl ether may be used. In addition, as another hydrogenation reaction method, for example, the copolymer according to the present invention before hydrogenation may be prepared by converting dicyclopentadienyl titanium halide, organic carboxylate nickel, organic carboxylate nickel and periodic table I to I Hydrogenation catalysts composed of Group III organometallic compounds, nickel, platinum, barium, ruthenium, rhenium, rhodium metal catalysts supported on carbon, silica, diatomaceous earth, etc., cobalt, nickel, rhodium, ruthenium complexes, etc. as catalysts Under hydrogen pressurized to about 0.1 to 10 MPa, or in the presence of lithium aluminum hydride, p-toluenesulfonyl hydrazide, Zr—Ti—Fe—V—Cr alloy, Zr—Ti—Nb—Fe—V— pressurized presence of Cr alloy, a hydrogen storage alloy such as LaNi ₅ alloy, or about 0.1~10MPa pressure Obtained by mixing a hydrogenated di-p-tolyl-bis (1-cyclopentadienyl) titanium / cyclohexane solution and an n-butyllithium / n-hexane solution under hydrogen. Examples of the method include hydrogenation using a hydrogenation catalyst under hydrogen pressurized to about 0.1 to 10 MPa.

Among the various hydrogenation catalysts described above, a Ziegler hydrogenation catalyst or a palladium-carbon hydrogenation catalyst comprising a combination of a transition metal compound and an alkylaluminum compound is preferred.
Such transition metal compounds include tris (acetylacetonato) cobalt, bis (acetylacetonato) nickel, tris (acetylacetonato) iron, tris (acetylacetonato) chromium, tris (acetylacetonato) manganese, bis (acetyl). Acetonato) manganese, tris (acetylacetonato) ruthenium, bis (acetylacetonato) cobalt, bis (cyclopentadienyl) dichlorotitanium, bis (cyclopentadienyl) dichlorozirconium, bis (triphenylphosphine) cobalt dichloride, Examples thereof include bis (2-hexanoate) nickel, bis (2-hexanoate) cobalt, titanium tetraisopropoxide, and titanium tetraethoxide. Among these, bis (acetylacetonato) nickel and tris (acetylacetonato) cobalt are preferable from the viewpoint of high hydrogenation activity.

  Alkyl aluminum compounds used for Ziegler hydrogenation catalysts include trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, tri-n-butylaluminum, dimethylaluminum chloride, diethylaluminum chloride, diisobutylaluminum chloride, methylaluminum. Examples include dichloride, ethylaluminum dichloride, isobutylaluminum dichloride, diethylaluminum hydride, diisobutylaluminum hydride, ethylaluminum sesquichloride and the like. Among these, triisobutylaluminum, triethylaluminum, and diisobutylaluminum hydride are preferable from the viewpoint of hydrogenation activity, and triisobutylaluminum is most preferable.

  Although there is no particular limitation on the use form of the Ziegler-type hydrogenation catalyst in the hydrogenation reaction, a method in which a catalyst solution in which a transition metal compound and an alkylaluminum compound are reacted in advance is prepared and added to the polymerization solution is preferably cited. I can do it. The amount of the alkylaluminum compound used in this case is preferably 0.2 to 5 mol with respect to 1 mol of the transition metal compound. The catalyst preparation reaction is carried out in a temperature range of about -40 to 100 ° C, preferably 0 to 80 ° C, and the reaction time is usually in the range of 1 minute to 3 hours.

  The hydrogenation reaction is usually performed at a temperature of 50 to 180 ° C., preferably 70 to 150 ° C., and at a hydrogen pressure of about 0.5 to 10 MPa, preferably 1 to 5 MPa. When the hydrogenation temperature is lower than 50 ° C., and when the hydrogen pressure is lower than 0.5 MPa, the catalytic activity is lowered, which is not preferable. When the hydrogenation temperature exceeds 180 ° C., catalyst deactivation, side reactions, etc. are likely to occur. Therefore, it is not preferable. In general, a Ziegler-type hydrogenation catalyst is a catalyst having a very high hydrogenation activity, and it is not preferable to set the hydrogen pressure higher than 10 MPa because it is not necessary and increases the burden on the apparatus.

In order to introduce a photocurable functional group into the terminal of the hydrogenated copolymer polyol according to the present invention, a photocurable functional group-containing compound, preferably a photocurable non-functional group, is added to the hydrogenated copolymer polyol. A saturated hydrocarbon group-containing compound, particularly preferably a (meth) acryloyl group-containing compound is reacted. Here, as the (meth) acryloyl group-containing compound, acryloyloxyalkyl isocyanate and methacryloyloxyalkyl isocyanate are preferable, and the hydrogenated copolymer polyol is (meth) acrylated by reaction with these.
Examples of the acryloyloxyalkyl isocyanate include 2-acryloyloxyethyl isocyanate, and examples of the methacryloyloxyalkyl isocyanate include 2-methacryloyloxyethyl isocyanate.

  In the photocurable composition of the present invention, a terminal (meth) acrylate oligomer can be blended as desired in addition to or as an alternative to the (meth) acrylate monomer. By blending this terminal (meth) acrylate oligomer, the viscosity of the photocurable composition can be adjusted, and physically, the hardness is reduced, and Eb (elongation) and Tb (breaking strength) are improved. Etc. can be achieved. The terminal (meth) acrylate oligomer refers to an oligomer having an acryloyl group or a methacryloyl group at one end or both ends.

Examples of the terminal (meth) acrylate oligomer include polyester (meth) acrylate oligomers, epoxy (meth) acrylate oligomers, urethane (meth) acrylate oligomers, polyol (meth) acrylate oligomers, and the like. As the polyester (meth) acrylate oligomer, for example, by esterifying the hydroxyl group of a polyester oligomer having hydroxyl groups at both ends obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol with (meth) acrylic acid, or It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding an alkylene oxide to a polyvalent carboxylic acid with (meth) acrylic acid. The epoxy (meth) acrylate oligomer can be obtained, for example, by reacting (meth) acrylic acid with an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolak type epoxy resin and esterifying it. Alternatively, it can be modified with isocyanate and the terminal hydroxyl group can be esterified with acrylic acid. The polyol (meth) acrylate oligomer can be obtained by esterifying the hydroxyl group of the polyether polyol with (meth) acrylic acid. The urethane (meth) acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by a reaction of polyether polyol or polyester polyol and polyisocyanate with (meth) acrylic acid.
The amount of the terminal (meth) acrylate oligomer blended into the photocurable composition of the present invention as desired is 100 parts by mass or less with respect to 100 parts by mass in total of the photocurable liquid resin and the (meth) acrylate monomer. Is preferred.

A stabilizer or the like may be further added to the photocurable composition of the present invention. As a stabilizer, triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate] [for example, Ciba Specialty Chemicals Co., Ltd., trade name: IRGANOX245, Asahi Manufactured by Denka Kogyo Co., Ltd., trade name: ADK STAB AO-70, etc.], 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1, 1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane [for example, manufactured by Asahi Denka Kogyo Co., Ltd., trade name: ADK STAB AO-80, etc.] Etc.
The amount of stabilizer blended in the photocurable composition of the present invention is preferably 0.1 to 5 parts by mass with respect to a total of 100 parts by mass of the photocurable liquid resin and the (meth) acrylate monomer, More preferably, it is 0.5-3 mass parts, More preferably, it is 0.5-2 mass parts.

  Furthermore, the photocurable composition of the present invention includes a terpene resin, a terpene phenol resin, a coumarone resin, a coumarone-indene resin, a petroleum hydrocarbon, for improving adhesion within a range that does not impair the effects of the present invention. Various tackifiers such as rosin derivatives and additives such as colorants such as titanium black can be added.

  A cured product can be obtained by reacting and curing the photocurable composition of the present invention by irradiation with active energy rays. It is preferable that the cured product has a JIS-A hardness of 60 or less because sufficient sealability can be obtained. From the same viewpoint, it is more preferably 20 to 60, further preferably 25 to 55, and particularly preferably 30 to 55.

The active energy ray used for reacting and curing the photocurable composition of the present invention refers to ultraviolet rays and ionizing radiation such as electron beams, α rays, β rays, and γ rays. Is preferred. Examples of the ultraviolet light source include a xenon lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, and a microwave excimer lamp. The atmosphere for irradiation with ultraviolet rays is preferably an inert gas atmosphere such as nitrogen gas or carbon dioxide gas, or an atmosphere with a reduced oxygen concentration, but can be sufficiently cured even in a normal air atmosphere. The irradiation atmosphere temperature can usually be 10 to 200 ° C.
In addition, the properties of the photo-curing resin can be stabilized by irradiating the active energy ray again after curing or by applying heat.

The manufacturing method of the photocurable composition of this invention is not specifically limited, A well-known method is applicable. For example, kneading each component and optionally used additive components using a kneader capable of adjusting the temperature, such as a single screw extruder, twin screw extruder, planetary mixer, twin screw mixer, high shear mixer, etc. Can be manufactured.
The gasket material for electronic parts of the present invention and other sealing materials can be produced by applying the photocurable composition thus obtained to an adherend and curing it by irradiation with energy rays. As the adherend, for example, one made of a hard resin can be used, but a metal one is preferable from the viewpoint of workability. There is no particular limitation on the metal, for example, cold-rolled steel sheet, galvanized steel sheet, aluminum / zinc alloy plated steel sheet, stainless steel sheet, aluminum plate, aluminum alloy plate, magnesium plate, magnesium alloy plate, etc. Can be used. Moreover, what injection-molded magnesium can also be used. From the viewpoint of corrosion resistance, a metal subjected to electroless nickel plating is preferable. As this electroless nickel plating method, a known method conventionally applied to metal materials, for example, nickel sulfate, sodium hypophosphite, lactic acid, propionic acid and the like containing pH 4.0-5. A method of immersing a metal plate in an electroless nickel plating bath made of an aqueous solution having a temperature of about 0 and a temperature of about 85 to 95 ° C. can be used.
In addition, applications of the sealing material include gaskets for HDDs, ink tank seals, liquid crystal seals, and the like. The thickness of the sealing material can be appropriately selected depending on the application, but is usually about 0.1 to 2.0 mm.

Arrangement or application of the photocurable composition to a substrate such as an adherend is performed by an arbitrary method using a coating liquid in which the temperature of the composition is adjusted as necessary and adjusted to a constant viscosity. For example, methods such as gravure coating, roll coating, spin coating, reverse coating, bar coating, screen coating, blade coating, air knife coating, dipping, dispensing, and inkjet can be used. After the photo-curable composition is disposed or applied and molded, the coating layer is cured by irradiating energy rays to obtain a sealing material.
In the sealing material, the cross-sectional shape of the sealing layer is such that the sealing layer is higher than the sealing layer width 1 from the viewpoint of efficiently using a space in an electronic device such as an HDD or a printing device while ensuring good sealing performance. Is preferably 0.2 to 2.0, more preferably 0.3 to 2.0. When the height cannot be obtained at one time, it can be applied in several times. In this case, it is also possible to cure by irradiating energy rays every time it is arranged or applied.
The sealing material of the present invention is suitable as a gasket material for electronic parts, and particularly suitable as a gasket material for HDD. In addition, the composition of the present invention can be suitably used as a pressing member for components in the HDD by arranging, applying, or molding the composition according to any method.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
The weight average molecular weight and molecular weight distribution of the conjugated diene-aromatic vinyl copolymer and the hardness, tackiness, compression set and siloxane solubility of the photocurable composition after curing were measured according to the following methods.
(1) Weight average molecular weight and molecular weight distribution Using the GPC method (Gel Permeation Chromatography), the weight average molecular weight and molecular weight distribution were obtained by polystyrene conversion.
(2) Hardness Based on JIS K 6253: 2006, the hardness of the cured product was measured with a type A durometer. As a test body, six sheets of the photocurable composition after curing having a thickness of about 1 mm were laminated, and a sheet having a thickness of about 6 mm was used.
(3) Adhesiveness A sheet of a photocurable composition after curing having a thickness of about 1 mm was prepared, and the tackiness was measured with a tackometer and displayed in units of gf.
(4) Compression set According to JIS K 6262: 2006, a sample of the photocurable composition after curing was measured after being allowed to stand at 100 ° C. and a compression rate of 25% for 24 hours, and further allowed to stand at room temperature for 24 hours. .
(5) Siloxane solubility A gas chromatographic mass of a specimen A1 formed and cured from a sheet having a thickness of about 1 mm and baked at a high temperature and a specimen A2 in which the specimen A1 was left indoors at room temperature for 2 weeks. The amount of siloxane was measured by an analytical method (GC-MS). {(Amount of siloxane in test body A2) − (Amount of siloxane in test body A1)} was defined as the dissolution amount. The unit was expressed as “per μg / 500 mg of material”.

Production Example Production of Photocurable Liquid Resin After adding 1 mol of 1,3- (diisopropenyl) benzene to a fully dehydrated and purified cyclohexane solvent, 2 mol of triethylamine and 2 mol of sec-butyllithium were sequentially added. The mixture was stirred at 50 ° C. for 2 hours to prepare a dilithium polymerization initiator.
In a 7 liter polymerization reactor purged with argon, 1.90 kg of dehydrated and purified cyclohexane, 2.00 kg of a hexane solution of 22.9% by mass of 1,3-butadiene monomer, and a cyclohexane solution of 20.0% by mass of styrene monomer were added. After adding 130.4 ml of a hexane solution of 0.765 kg, 1.6 mol / liter of 2,2-di (tetrahydrofuryl) propane, 108.0 ml of a 0.5 mol / liter dilithium polymerization initiator was added. Polymerization was started.
Polymerization was carried out for 1.5 hours while raising the temperature of the polymerization reactor to 50 ° C., then 108.0 ml of a 1 mol / liter ethylene oxide cyclohexane solution was added, and the mixture was further stirred for 2 hours, and then 50 ml of isopropyl alcohol was added. did. A hexane solution of the copolymer was precipitated in isopropyl alcohol and sufficiently dried to obtain a copolymer polyol. This copolymer polyol was an OH group styrene-butadiene copolymer at both terminals, the styrene content was 25% by mass, the weight average molecular weight was 14,500, and the molecular weight distribution was 1.20.

Next, 120 g of copolymer polyol was dissolved in 1 liter of hexane that had been sufficiently dehydrated and purified, and then nickel naphthenate, triethylaluminum, and butadiene prepared in separate containers in a 1: 3: 3 (molar ratio) ratio. The catalyst solution was charged so that the amount of nickel was 1 mol with respect to 1,000 mol of the butadiene portion in the copolymer solution. Hydrogen was added under pressure to 27,580 hPa (400 psi) in a sealed reaction vessel, and a hydrogenation reaction was performed at 110 ° C. for 4 hours. Thereafter, the catalyst residue was extracted and separated with hydrochloric acid having a concentration of 3 mol / L, and further centrifuged to separate and separate the catalyst residue. Thereafter, the hydrogenated copolymer polyol was precipitated in isopropyl alcohol and further sufficiently dried.
100 g of the fully dried hydrogenated copolymer polyol was dissolved in cyclohexane, and 2-acryloyloxyethyl isocyanate (manufactured by Showa Denko KK: Karenz AOI) was slowly added dropwise while maintaining the temperature at 40 ° C. and sufficiently stirring. Thereafter, the mixture was further stirred for 4 hours, precipitated in isopropyl alcohol and dried. The amount of 2-acryloyloxyethyl isocyanate added was 2.49 g. As described above, an acryloyl group-containing hydrogenated styrene-butadiene copolymer, which is a photocurable liquid resin, was obtained from the hydrogenated polymer polyol.

Examples 1-4 and Comparative Examples 1-7
11 kinds of photocurable compositions of Examples 1 to 4 and Comparative Examples 1 to 7, which were kneaded in a planetary mixer according to the formulation shown in Tables 1 and 2 using the above photocurable liquid resin. Got. Using the obtained composition, it formed into the shape prescribed | regulated to said measuring method, and irradiated with energy rays to this, and hardened | cured material was obtained. A metal halide lamp was used as a light source for energy rays, and irradiation was performed under an air atmosphere under conditions of an illuminance of about 160 mW / cm ² (wavelength 320 to 390 nm) and an integrated light amount of about 9,000 mJ / cm ² . About the obtained hardened | cured material, hardness, adhesiveness, compression set, and siloxane solubility were evaluated by said method. The results are shown in Tables 1 and 2.

［注］
光硬化性液状樹脂： 製造例により得られたアクリロイル基含有水添スチレン−ブタジエン共重合体
アクリレートモノマーＡ： イソボルニルアクリレート、大阪有機化学工業（株）製、商品名：ＩＢＸＡ
揺変剤： 水添ひまし油、ロックウッド アディティブス（株）製、商品名：ＡＤＶＩＴＲＯＬ１００、
光重合開始剤Ａ： ２−ベンジル−２−ジメチルアミノ−１−（４−モルホリノフェニル）−１−ブタノン、チバ・スペシャルティ・ケミカルズ（株）製、商品名：イルガキュア３６９
光重合開始剤Ｂ： ２−メチル−１−［４−（メチルチオ）フェニル］−２−モルホリノプロパン−１−オン、チバ・スペシャルティ・ケミカルズ（株）製、商品名：イルガキュア９０７
光重合開始剤Ｃ： ２−ヒドロキシ−１−｛４−［４−（２−ヒドロキシ−２−メチル−プロピオニル）−ベンジル］フェニル｝−２−メチル−プロパン−１−オン、チバ・スペシャルティ・ケミカルズ（株）製、商品名：イルガキュア１２７
光重合開始剤Ｄ： ２−ヒドロキシ−２−メチル−１−フェニル−プロパンー１−オン、チバ・スペシャルティ・ケミカルズ（株）製、商品名：ダロキュア１１７３
光重合開始剤Ｅ： １−ヒドロキシ−シクロヘキシル−フェニルケトン、チバ・スペシャルティ・ケミカルズ（株）製、商品名：イルガキュア１８４
光重合開始剤Ｆ： ２，２−ジメトキシ−１，２−ジフェニルエタン−１−オン、チバ・スペシャルティ・ケミカルズ（株）製、商品名：イルガキュア６５１
光重合開始剤Ｇ： オリゴ［２−ヒドロキシ−２−メチル−１−［４−（１−メチルビニル）フェニル］プロパノン］、Ｌａｍｂｅｒｔｉ Ｓ．ｐ．Ａ製、商品名：ＥＳＡＣＵＲＥ ＫＩＰ１５０

[note]
Photocurable liquid resin: Acrylyl group-containing hydrogenated styrene-butadiene copolymer acrylate monomer A obtained by Production Example: Isobornyl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name: IBXA
Thixotropic agent: Hydrated castor oil, manufactured by Rockwood Additives, Inc., trade name: ADVITROL100,
Photopolymerization initiator A: 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, manufactured by Ciba Specialty Chemicals Co., Ltd., trade name: Irgacure 369
Photopolymerization initiator B: 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, manufactured by Ciba Specialty Chemicals, Inc., trade name: Irgacure 907
Photopolymerization initiator C: 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one, Ciba Specialty Chemicals Product name: Irgacure 127
Photopolymerization initiator D: 2-hydroxy-2-methyl-1-phenyl-propan-1-one, manufactured by Ciba Specialty Chemicals, Inc., trade name: Darocur 1173
Photopolymerization initiator E: 1-hydroxy-cyclohexyl-phenyl ketone, manufactured by Ciba Specialty Chemicals, Inc., trade name: Irgacure 184
Photopolymerization initiator F: 2,2-dimethoxy-1,2-diphenylethane-1-one, manufactured by Ciba Specialty Chemicals Co., Ltd., trade name: Irgacure 651
Photoinitiator G: Oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone], Lamberti S. p. Product name A: ESACURE KIP150

［注］
光硬化性液状樹脂、揺変剤及び光重合開始剤Ａ〜Ｄは、表１と同じ。
アクリレートモノマーＢ： ジシクロペンタニルアクリレート、日立化成工業（株）製、商品名：ＦＡ−５１３Ａ

[note]
The photocurable liquid resin, thixotropic agent, and photopolymerization initiators AD are the same as in Table 1.
Acrylate monomer B: dicyclopentanyl acrylate, manufactured by Hitachi Chemical Co., Ltd., trade name: FA-513A

As is clear from Table 1, all of the photocurable compositions of Examples 1 to 4 of the present invention had moderate hardness, and both tackiness and compression set were small. These photocurable compositions of Examples 1 to 4 were dispensed into an HDD container with a dispenser, and then photocured to form gaskets. When the reworkability of these gaskets was confirmed, good reworkability was exhibited.
On the other hand, in the photocurable compositions of Comparative Examples 1 and 6, the surface of the photocurable composition was cured, but the internal curing was insufficient. Therefore, the tackiness of the photocurable composition was small, but the compression set was large and the reworkability was insufficient.
Moreover, the photocurable composition of Comparative Examples 2-5 and 7 had large adhesiveness, and rework property was inadequate.
Furthermore, it was confirmed that the photocurable compositions of the present invention using the hydrogenated conjugated diene-aromatic vinyl copolymer have a very low siloxane solubility and are excellent in quality maintenance of electronic parts such as HDDs. It was.

  The photocurable composition of the present invention is suitably used as a sealing material for various applications, for example, for gaskets for electronic components, ink tank seals, liquid crystal seals, and the like, and particularly preferably for HDD gaskets.

Claims (8)

  In a photocurable composition containing a photocurable liquid resin, a (meth) acrylate monomer and a photopolymerization initiator, the photocurable liquid resin is a hydrogenated conjugated diene-aromatic vinyl copolymer containing a photocurable functional group. A photocurable composition comprising a combination, and the photopolymerization initiator contains at least an aminoacetophenone photopolymerization initiator.   The photocurable composition according to claim 1, wherein the conjugated diene monomer constituting the hydrogenated conjugated diene-aromatic vinyl copolymer is 1,3-butadiene and / or isoprene.   The photocurable composition according to claim 1 or 2, wherein the aromatic vinyl monomer constituting the hydrogenated conjugated diene-aromatic vinyl copolymer is styrene, α-methylstyrene, and / or paramethylstyrene.   The photocurable composition according to claim 1, wherein the photocurable functional group is a photocurable unsaturated hydrocarbon group.   The photocurable composition according to claim 4, wherein the photocurable unsaturated hydrocarbon group is a (meth) acryloyl group.   The aminoacetophenone photopolymerization initiator is 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) Initiation of photopolymerization selected from the group consisting of) -1-butanone and 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- (4-morpholinophenyl) -1-butanone It is an agent, The photocurable composition in any one of Claims 1-5.   Furthermore, the photocurable composition in any one of Claims 1-6 formed by containing a thixotropic agent.   The gasket for electronic components which uses the photocurable composition in any one of Claims 1-7.