JP5619551B2 - Gasket material, gasket and hard disk device - Google Patents

Description

  The present invention has moderate surface tackiness at room temperature (about 15-30 ° C.), excellent leakage resistance, and increased surface tackiness of a gasket after being placed in a high temperature (for example, 80-90 ° C.) environment. The present invention relates to a gasket material, a gasket, and a hard disk device using the gasket.

In recent years, HDDs (hard disk drives) of computers have become more sophisticated and smaller in size and have a complicated circuit configuration, and even a small amount of dust or moisture can cause damage. There is an increasing need for prevention of moisture intrusion, and it is common practice to prevent entry of dust and moisture using a gasket.
In recent years, with the miniaturization of such HDDs, or in order to reduce capital investment and processing costs, a photocurable composition is applied to an adherend by a dispenser from a conventional injection molding, and then activated. A method of manufacturing a gasket has been adopted by curing with an energy ray (see, for example, Patent Documents 1 to 3). In order to obtain sufficient sealing properties as a gasket, a urethane acrylate oligomer is used as a main component in the photocurable composition so that the cured product has a low hardness.

WO96 / 10594 pamphlet JP 2003-7047 A JP 2004-26919 A

In general, HDD gaskets may be broken due to temperature changes, compression or expansion in the environment of use. Therefore, in order to inspect whether or not it can be used as an HDD gasket, a thermal shock test (heat shock test) is usually performed while compressing the gasket material. The test is a test in which a load is applied to a material by repeatedly performing an environmental change between a low temperature and a high temperature in a short period of time. Conventionally known gaskets have many materials that are destroyed in the heat shock test. Therefore, development of gasket materials that are more excellent in durability than conventional materials is eagerly desired.
Therefore, the problem of the present invention is that the surface of the gasket after having a suitable surface adhesiveness at room temperature (about 15 to 30 ° C.), excellent leakage resistance, and in a high temperature (for example, 80 to 90 ° C.) environment. An object of the present invention is to provide a gasket material in which an increase in adhesiveness is suppressed, a gasket obtained by irradiating the material with active energy rays, and a hard disk device using the gasket.

As a result of intensive studies to solve the above problems, the present inventor has succeeded in developing a material that can sufficiently withstand the heat shock test by elucidating the mechanism of material destruction in the heat shock test. The present inventor found that the material destruction in the heat shock test is not only a load is applied in the compression direction of the gasket, but also the two metal substrates sandwiching the gasket are thermally expanded and contracted at different ratios due to a rapid temperature change. In addition, shear stress is applied to the gasket adhered to the two metal substrates, and the surface adhesiveness of the gasket is increased by being placed in a high temperature environment, so that the metal substrate and the gasket are more firmly adhered to each other. It was assumed that the material was broken because the gasket was easily subjected to the shear stress. Based on this assumption, it has moderate surface tackiness at room temperature (about 15 to 30 ° C.), excellent leak resistance, and the surface tackiness of the gasket after being placed in a high temperature (for example, 80 to 90 ° C.) environment. It was concluded that a material whose increase is suppressed can reduce shear stress in a high-temperature environment and avoid material destruction.
Specifically, if it is a material mainly composed of an energy ray-curable liquid oligomer having a (meth) acryloyl group and containing a (meth) acrylic monomer having a specific structure, room temperature (about 15 to about 30 ° C) has moderate surface tackiness and excellent leakage resistance, and suppresses an increase in the surface tackiness of the gasket after being placed in a high temperature (for example, 80 to 90 ° C) environment, which is sufficient for a heat shock test. Found that it can withstand.

（式中、Ｒ¹は、水素原子又はメチル基を表し、Ｒ²は、炭素数４〜１８の鎖式飽和脂肪族炭化水素基を表す。Ｗは、エチレン基又はプロピレン基を表す。また、ｎは、０〜２の整数を表す。）
［２］さらに、前記（Ａ）成分と（Ｂ）成分の合計量１００質量部に対して、光重合開始剤０．１〜１０質量部、並びに無機充填材及び／又は有機系チクソ性付与剤を０．１〜３０質量部含有し、かつ前記（Ａ）成分と（Ｂ）成分との配合比［（Ａ）：（Ｂ）］が、質量比で７５：２５〜２０：８０である、上記［１］に記載のガスケット用材料。
［３］前記無機充填材がシリカである、上記［２］に記載のガスケット用材料。
［４］上記［１］〜［３］のいずれかに記載の材料に活性エネルギー線を照射して得られるガスケット。
［５］ハードディスクドライブ（ＨＤＤ）用である、上記［４］に記載のガスケット。
［６］上記［４］又は［５］に記載のガスケットを用いたハードディスク装置。 That is, the present invention relates to the following [1] to [6].
[1] A gasket material containing (A) an energy ray-curable liquid oligomer having a (meth) acryloyl group and (B) a (meth) acrylate monomer represented by the following general formula (1): The material for gaskets whose compounding ratio [(A) :( B)] of a component) and a component (B) is 80 : 20-20 : 80 by mass ratio.

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a chain saturated aliphatic hydrocarbon group having 4 to 18 carbon atoms, and W represents an ethylene group or a propylene group. n represents an integer of 0 to 2.)
[2] Further, 0.1 to 10 parts by mass of a photopolymerization initiator, and an inorganic filler and / or an organic thixotropic agent with respect to 100 parts by mass of the total amount of the components (A) and (B). 0.1 to 30 parts by mass , and the mixing ratio [(A) :( B)] of the component (A) and the component (B) is 75:25 to 20:80 by mass ratio . The gasket material according to the above [1].
[3] The gasket material according to [2], wherein the inorganic filler is silica.
[4] A gasket obtained by irradiating the material according to any one of [1] to [3] with active energy rays.
[5] The gasket according to [4], which is for a hard disk drive (HDD).
[6] A hard disk device using the gasket according to [4] or [5].

  The gasket material of the present invention has moderate surface tackiness at room temperature (about 15 to 30 ° C.), excellent leakage resistance, and the surface of the gasket after being placed in a high temperature (for example, 80 to 90 ° C.) environment. Increase in adhesiveness is suppressed. Therefore, the gasket obtained by irradiating the active energy ray to the material is excellent in durability, and can sufficiently withstand a heat shock test for the gasket for HDD.

[Materials for gaskets]
The gasket material of the present invention comprises (A) component as an energy ray-curable liquid oligomer having a (meth) acryloyl group, and (B) component as a (meth) acrylate monomer represented by the following general formula (1). It is the material for gaskets containing.
Hereinafter, each component will be described in detail.

((A) Energy ray curable liquid oligomer)
In the gasket material of the present invention, an energy beam curable liquid oligomer having a (meth) acryloyl group is used as the component (A). As this energy ray curable liquid oligomer, an oligomer having at least two (meth) acryloyl groups in the molecule can be suitably used from the viewpoint of performance and processability of the obtained gasket. The number of (meth) acryloyl groups in one molecule is usually about 2 to 6, preferably 2 to 4, particularly preferably 2.
The (meth) acryloyl group refers to an acryloyl group or a methacryloyl group.

There is no restriction | limiting in particular as an energy-beam curable oligomer which has a (meth) acryloyl group, For example, a urethane type (meth) acrylate oligomer, a polyester type (meth) acrylate oligomer, a polyether type (meth) acrylate oligomer, a polycarbonate type (meta ) Acrylate oligomers, epoxy (meth) acrylate oligomers, conjugated diene polymer (meth) acrylate oligomers and hydrogenated products thereof.
Here, the urethane-based (meth) acrylate oligomer is obtained by, for example, esterifying a polyurethane oligomer obtained by the reaction of a polyisocyanate with polyether polyol, polyester polyol, carbonate diol, or the like with (meth) acrylic acid. Can do.
Polyester (meth) acrylate oligomers can be obtained by, for example, esterifying the hydroxyl groups of polyester oligomers having hydroxyl groups at both ends obtained by condensation of polyvalent carboxylic acids and polyhydric alcohols with (meth) acrylic acid, It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding alkylene oxide to carboxylic acid with (meth) acrylic acid.

The polyether-based (meth) acrylate oligomer can be obtained by esterifying the hydroxyl groups at both ends of the polyether polyol oligomer with (meth) acrylic acid. The polycarbonate (meth) acrylate oligomer can be obtained by esterifying the hydroxyl groups at both ends of the polycarbonate polyol oligomer with (meth) acrylic acid. The epoxy-based (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. A carboxyl-modified epoxy acrylate oligomer obtained by partially modifying this epoxy-based (meth) acrylate oligomer with a dibasic carboxylic acid anhydride can also be used.
Examples of the conjugated diene polymer (meth) acrylate oligomer include SBR diacrylate obtained by acrylic modification of a liquid styrene-butadiene copolymer, and polyisoprene acrylate obtained by acrylic modification of polyisoprene. It is done. The hydrogenated conjugated diene polymer (meth) acrylate oligomer can be obtained, for example, by esterifying the hydroxyl group of hydrogenated polybutadiene or hydrogenated polyisoprene having hydroxyl groups at both ends with (meth) acrylic acid.
In addition, (meth) acrylate refers to acrylate or methacrylate, and (meth) acrylic acid refers to acrylic acid or methacrylic acid.

In the present invention, the energy ray-curable liquid oligomer having a (meth) acryloyl group may be used alone or in combination of two or more. Among the oligomers, a bifunctional urethane (meth) acrylate oligomer is preferable from the viewpoint of the performance and processability of the obtained gasket. The bifunctional urethane-based (meth) acrylate oligomer means that two (meth) acryloyl groups are contained in one molecule of the urethane-based (meth) acrylate oligomer.
The bifunctional urethane-based (meth) acrylate oligomer can be obtained by reacting a polyether polyol, polyester polyol, carbonate diol or the like having two hydroxy groups in the molecule with a polyisocyanate.

Examples of the polyether polyol having two hydroxy groups include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol and 1,3-butylene glycol, 1,4-butylene glycol, neopentyl glycol, A compound in which ethylene oxide or propylene oxide is added to cyclohexanedimethanol, 2,2-bis (4-hydroxycyclohexyl) propane, bisphenol A, or the like can be used.
The polyester polyol having two hydroxy groups can be obtained by reacting an alcohol component and an acid component. For example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1,3-butylene glycol, 1,4 A compound in which ethylene oxide or propylene oxide is added to butylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 2,2-bis (4-hydroxycyclohexyl) propane, bisphenol A, Alternatively, a compound or the like to which ε-caprolactone is added can be used as an alcohol component, and a dibasic acid such as adipic acid, sebacic acid, azelaic acid, or dodecanedicarboxylic acid, and an anhydride thereof can be used as the acid component. A compound obtained by reacting the above-mentioned alcohol component, acid component and ε-caprolactone at the same time can also be used as the polyester polyol.

Examples of the carbonate diol include diaryls such as diphenyl carbonate, bis-chlorophenyl carbonate, dinaphthyl carbonate, phenyl-toluyl carbonate, phenyl-chlorophenyl carbonate, 2-tolyl-4-tolyl-carbonate, dimethyl carbonate, and diethyl carbonate. Carbonates or dialkyl carbonates and diols such as 1,6-hexanediol, neopentyl glycol, 1,4-butanediol, 1,8-octanediol, 1,4-cyclohexanedimethanol, 2-methylpropanediol , Dipropylene glycol, dibutylene glycol or the above diol compounds and oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, hexahydrophthalic acid, etc. Reaction products of carboxylic acids, or can be obtained by transesterification of the polyester diol is the reaction product of ε- caprolactone.
The carbonate diol thus obtained is a polycarbonate diol having two or more carbonate structures in the molecule.

In the gasket material of the present invention, a compound obtained by reacting an organic diisocyanate with the polyether polyol or polyester polyol as the bifunctional urethane-based (meth) acrylate oligomer is preferable. As the organic diisocyanate, for example, cycloaliphatic and aliphatic diisocyanates such as isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate and hexamethylene diisocyanate are preferably used.
In the present invention, as the bifunctional urethane-based (meth) acrylate oligomer, an oligomer having a number average molecular weight of about 4,000 to 8,000 is preferable from the viewpoint of handling properties. The number average molecular weight is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

((B) (Meth) acrylate monomer)
In the gasket material of the present invention, a specific (meth) acrylate monomer represented by the following general formula (1) is used as the component (B). By blending the component (B) with the gasket material, the surface after the gasket is placed in a high temperature environment while the surface tackiness at room temperature (about 15 to 30 ° C.) is moderate and the leakage resistance is excellent. An increase in adhesiveness can be suppressed, and a gasket that can sufficiently withstand a heat shock test for an HDD gasket can be manufactured.

In the general formula (1), R ¹ represents a hydrogen atom or a methyl group, and R ² represents a chain saturated aliphatic hydrocarbon group having 4 to 18 carbon atoms. W represents an ethylene group or a propylene group. Moreover, n represents the integer of 0-2.
R ¹ is preferably a hydrogen atom from the viewpoint of availability.
The chain saturated aliphatic hydrocarbon group having 4 to 18 carbon atoms represented by R ² is not particularly limited as long as it is a chain saturated aliphatic hydrocarbon group having a total carbon number of 4 to 18, for example, n-butyl group (C4), isobutyl group (C4), s-butyl group (C4), n-hexyl group (C6), ethylhexyl group (C8), n-octyl group (C8), isooctyl group (C8), Various decyl groups (C10) ("various" means including straight chain and all branched chains. The same applies hereinafter), various dodecyl groups (C12), various tridecyl groups (C13), various hexadecyl groups (C16), various octadecyl groups (C18) and the like. Among these, a branched chain saturated aliphatic hydrocarbon group having 7 to 18 carbon atoms is preferable from the viewpoint of suppressing an increase in surface adhesion after placing the gasket in a high temperature environment, and an ethylhexyl group, an isooctyl group (6 -Methylheptyl group), n-dodecyl group (lauryl group), isomyristyl group, and isostearyl group are more preferable.
When the carbon number of R ² is 3 or less, or 19 or more, or R ² is an alicyclic hydrocarbon group or an aromatic hydrocarbon group, it is sufficient for a heat shock test for HDD gaskets. No durable gasket is available.
W is preferably an ethylene group from the viewpoint of availability.
If n is an integer of 0 to 2, it does not affect the effect of suppressing the increase in adhesiveness in the high temperature environment of the gasket of the present invention.
(B) component (meth) acrylate monomer may be used individually by 1 type, and may be used in combination of 2 or more type.

  The mixing ratio of the component (A) and the component (B) is (A) :( B) = 97: 3 to 20:80 in terms of mass ratio, but the adhesion after placing the gasket in a high temperature environment. From the viewpoint of suppressing the increase in property, the ratio is preferably 95: 5 to 20:80, more preferably 90:10 to 40:60, and still more preferably 80:20 to 70:30.

  The gasket material of the present invention is of an active energy ray curable type, and as the active energy ray, ionizing radiation such as ultraviolet rays; electron rays; α rays, β rays, γ rays can be used. From the viewpoint of productivity and economy, it is preferable to use ultraviolet rays. When ultraviolet rays are used, the gasket material preferably contains a photopolymerization initiator described later. In addition, when ionizing radiation like an electron beam or a gamma ray is used, curing can proceed promptly without the inclusion of a photopolymerization initiator.

(Photopolymerization initiator)
As the photopolymerization initiator that is a component, known ones can be widely used, and are not particularly limited.
For example, intramolecular cleavage type photopolymerization initiators may be mentioned, and benzoin alkyl ether photopolymerization initiators such as benzoin ethyl ether, benzoin isobutyl ether and benzoin isopropyl ether; 2,2-diethoxyacetophenone, 4′-phenoxy-2 , 2-dichloroacetophenone and other acetophenone photopolymerization initiators; 2-hydroxy-2-methylpropiophenone, 4′-isopropyl-2-hydroxy-2-methylpropiophenone, 4′-dodecyl-2-hydroxy- Propiophenone photopolymerization initiators such as 2-methylpropiophenone; anthraquinone photopolymerization initiators such as benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone and 2-ethylanthraquinone, 2-chloroanthraquinone; acylphosphine Side-based photopolymerization initiators, and the like. Among these, propiophenone-based photopolymerization initiators are preferable, and 2-hydroxy-2-methylpropiophenone is more preferable.
Other hydrogen abstraction type photopolymerization initiators include benzophenone / amine photopolymerization initiators, Michler ketone / benzophenone photopolymerization initiators, and thioxanthone / amine photopolymerization initiators.
In order to avoid migration of the unreacted photopolymerization initiator, a non-extractable photopolymerization initiator can be used. For example, there are those obtained by polymerizing an acetophenone-based initiator and those obtained by adding a double bond of acrylic group to benzophenone.
These photoinitiators may be used individually by 1 type, and may be used in combination of 2 or more type.
When the photopolymerization initiator is blended in the gasket material of the present invention, the blending amount is usually 100 parts by mass of the total amount of the component (A) and the component (B) contained in the gasket material. Preferably it is about 0.1-10 mass parts, More preferably, it is 0.5-5 mass parts, More preferably, it is 0.5-3 mass parts. Moreover, a well-known photosensitizer can also be used together with the said photoinitiator.

(Optional component)
In the gasket material of the present invention, as long as the object of the present invention is not impaired, as an optional component, for example, a (meth) acryl monomer other than the component (B), an inorganic filler, an organic material, and the like Thixotropic agents, coupling agents, antioxidants (anti-aging agents), light stabilizers, carbodiimides, and other fatty acids such as stearic acid; fatty acid metal salts such as calcium stearate; stearic acid amide, etc. Fatty acid amides; fatty acid esters; internal mold release agents such as polyolefin wax and paraffin wax; softeners such as process oil; colorants; leveling agents and the like. The gasket material of the present invention is basically solvent-free, but various solvents may be blended as necessary.
In particular, by adding an inorganic filler or an organic thixotropic agent to the gasket material of the present invention, the material is imparted with thickening and thixotropy, thereby improving the moldability of the gasket material. be able to.
Hereinafter, these optional components will be described.

((Meth) acrylic monomer other than component (B))
The present invention does not deny the blending of (meth) acrylic monomers other than the component (B). As the (meth) acrylic monomer other than the component (B), a (meth) acrylic monomer having a molecular weight of less than 1,000 is preferable. For example, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl ( (Meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, diethylene glycol monoethyl ether (meth) acrylate, dimethylaminoethyl (meth) acrylate, dipropylene glycol mono (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, ethoxylated phenyl (Meth) acrylate, ethyl (meth) acrylate, isoamyl (meth) acrylate, isobornyl (meth) acrylate, isobutyl (meth) acrylate, isodecyl (meth) Chryrate, isooctyl (meth) acrylate, isostearyl (meth) acrylate, isomyristyl (meth) acrylate, lauroxy polyethylene glycol (meth) acrylate, lauryl (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxytripropylene glycol And monofunctional (meth) acrylate monomers such as (meth) acrylate, methoxypolyethylene glycol (meth) acrylate and methoxytriethylene glycol (meth) acrylate.
When the (meth) acrylic monomer other than the component (B) is blended in the gasket material of the present invention, the blending amount may be a level that does not significantly impair the effects of the present invention. It is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less with respect to 100 parts by mass of the total amount of component B).

(Inorganic filler)
Examples of the inorganic filler include silica (SiO ₂ ), alumina, titania, and viscosity mineral. Among these, silica is preferable. More specifically, silica fine powder [for example, Nippon Aerosil Co., Ltd., trade name: Aerosil 300, etc.] finely pulverized by a dry method may be used.
The average particle diameter of the inorganic filler is preferably 5 to 50 μm, more preferably 5 to 12 μm, from the viewpoint of thickening and thixotropy.
When the inorganic filler is blended in the gasket material of the present invention, the blending amount is usually preferably with respect to 100 parts by mass of the total amount of the component (A) and the component (B) contained in the gasket material. Is about 0.1 to 30 parts by mass, more preferably 1 to 15 parts by mass, and still more preferably 5 to 15 parts by mass.

(Organic thixotropic agent)
As the organic thixotropic agent, hydrogenated castor oil, amide wax or a mixture thereof is preferable. Specifically, hydrogenated castor oil which is a hydrogenated product of castor oil (non-drying oil whose main component is ricinoleic acid) [for example, product name: ADVITROL100, manufactured by Enomoto Kasei Co., Ltd., product name : Disparon 305 etc.] and higher amide waxes that are compounds in which hydrogen of ammonia is substituted with an acyl group [for example, trade name: Disparon 6500 etc., manufactured by Enomoto Kasei Co., Ltd.].
These may be used alone or in combination of two or more, or may be used in combination with the inorganic filler.
When the organic thixotropic agent is blended in the gasket material of the present invention, the blending amount thereof is 100 parts by mass with respect to the total amount of the component (A) and the component (B) contained in the gasket material. Usually, it is preferably about 0.1 to 30 parts by mass, more preferably 1 to 15 parts by mass, and further preferably 5 to 15 parts by mass. In addition, when using together an organic type thixotropic agent and an inorganic filler, it is preferable that the total amount is the said range.

(Coupling agent)
When producing a member with a gasket, the coupling agent may be used in an appropriate amount in the gasket material of the present invention as necessary in order to improve the adhesion between the gasket and the substrate. Examples of the coupling agent include a silane coupling agent, a titanate coupling agent, and an aluminum coupling agent. Among these coupling agents, a silane coupling agent is preferable.
The silane coupling agent is not particularly limited, but examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropyltriethoxysilane. Saturated group-containing silane coupling agents; glycidyl group-containing silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyltriethoxysilane; γ-aminopropyltrimethoxysilane, γ-aminopropyltri Amino group-containing silane coupling agents such as ethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane; γ-mercaptopropyl Trimethoxysilane, γ- Mercapto group-containing silane coupling agents such as Le mercaptopropyl triethoxysilane, and the like. These silane coupling agents may be used singly or in combination of two or more.
When a coupling agent is blended in the gasket material of the present invention, the blending amount is usually preferably based on 100 parts by mass of the total amount of the component (A) and the component (B) contained in the gasket material. Is about 0.1 to 20 parts by mass, more preferably 1 to 15 parts by mass, and still more preferably 3 to 15 parts by mass.

(Antioxidant)
Examples of the antioxidant include phenolic antioxidants, sulfur antioxidants, and phosphorus antioxidants.
Examples of phenolic antioxidants include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4- Hydroxy-5-tert-butylphenylbutane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis -[Methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis- (4′-hydroxy-3′-t-butyl) Phenyl) butyric acid] glycol ester, 1,3,5-tris (3 ′, 5′-di-t-butyl-4′-hydroxybenzyl) -S-triazine-2,4,6- (1H, 3H , 5H) trione, α-tocopherol and the like.

Examples of the sulfur antioxidant include dilauryl 3,3′-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, and the like.
Examples of phosphorus antioxidants include triphenyl phosphite, diphenylisodecyl phosphite, phenylisodecyl phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 2,2'-methylenebis (4,6-di-t-butylphenyl) octyl phosphite and the like can be mentioned.

These antioxidants may be used individually by 1 type, and may be used in combination of 2 or more type.
When the antioxidant is blended in the gasket material of the present invention, the blending amount is appropriately selected according to the type, but with respect to 100 parts by mass of the total amount of the component (A) and the component (B), Usually, it is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 5 parts by mass.

(Light stabilizer)
Examples of the light stabilizer include benzophenone-based, benzotriazole-based, benzoate-based or triazine-based ultraviolet absorbers, hindered amine-based light stabilizers, and the like. Among these, hindered amine-based light stabilizers are preferable.
Examples of the hindered amine light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 4 -Benzoyloxy-2,2,6,6-tetramethylpiperidine, 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine, 1,2,2,6,6-pentamethyl-4-piperidinyl-methacrylate Bis (1,2,2,6,6-pentamethyl-4-piperidinyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl ] Butylmalonate, decanedioic acid bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester, N, N ', N ", N"'-tetrakis- (4 , 6-Bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine Dibutylamine-1,3,5-triazine-N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6 , 6-Tetramethyl-4-piperidyl) butylamine polycondensate, poly [[6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperi Dil) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]], dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol 2,2,4,4-tetramethyl-20- (β-lauryloxycarbonyl) ethyl-7-oxa-3,20-diazadispiro [5.1.1.12] heneicosane-21-one, β-alanine, N,-(2,2,6,6-tetramethyl-4-piperidinyl) -dodecyl ester / tetradecyl ester, N-acetyl-3-dodecyl-1- (2,2,6,6- Tetramethyl-4-piperidinyl) pyrrolidine-2,5-dione, 2,2,4,4-tetramethyl-7-oxa-3,20-diazadispiro [5.1.1.12] heneicosane- 21-one, 2,2,4,4-tetramethyl-21-oxa-3,20-diazadicyclo- [5.1.1.12] -heneicosane-20-propanoic acid dodecyl ester / tetradecyl ester propanedioic Acid, [(4-methoxyphenyl) -methylene] -bis (1,2,2,6,6-pentamethyl-4-piperidinyl) ester, higher fatty acid of 2,2,6,6-tetramethyl-4-piperidinol And esters such as 1,3-benzenedicarboxamide-N, N′-bis (2,2,6,6-tetramethyl-4-piperidinyl).

A light stabilizer may be used individually by 1 type, and may be used in combination of 2 or more type.
When the light stabilizer is blended in the gasket material of the present invention, the blending amount is appropriately selected according to the type, but with respect to 100 parts by mass of the total amount of the component (A) and the component (B). Usually, it is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass.

(Carbodiimides)
As the carbodiimides, for example, commercially available products such as “Elastostab H01” (manufactured by Nisshinbo Industries, Inc.) can be used.
When the carbodiimides are blended in the gasket material of the present invention, the blending amount is appropriately selected according to the type, and is usually based on 100 parts by mass of the total amount of the component (A) and the component (B). , Preferably it is 0.01-5 mass parts, More preferably, it is 0.1-3 mass parts.

(Adhesion improver)
Examples of the adhesive improver used in the gasket material of the present invention include terpene resins, terpene phenol resins, coumarone resins, coumarone-indene resins, petroleum hydrocarbons, rosin derivatives, and the like. A seed may be used independently and may be used combining two or more sorts.

[Preparation of gasket material]
There is no restriction | limiting in particular in the preparation method of the material for gaskets of this invention, A well-known method is applicable. For example, the component (A), the component (B) and the photopolymerization initiator used as required and the optional component can be kneaded with a temperature, for example, a single screw extruder, a twin screw extruder, a planetary mixer, It can be prepared by kneading using a biaxial mixer, a high shear mixer or the like.
The gasket material of the present invention thus obtained preferably has a viscosity in the range of 1 to 10,000 Pa · s at a temperature of 50 ° C. and a shear rate of 1.0 / second. When the viscosity is in the above range, the gasket material has appropriate fluidity, good handling properties, and can maintain the gasket shape. The viscosity is more preferably 10 to 2,000 Pa · s, still more preferably 30 to 1,000 Pa · s.
The viscosity is a value measured by the following method.
(Viscosity of gasket material at a temperature of 50 ° C. and a shear rate of 1.0 / second)
Rheometer “RS-600” (manufactured by Harke) was used for measurement. Casson in which the material for the gasket was adjusted to 50 ° C., the shear stress was measured while changing the shear rate in the range of ¹ to 10 s ⁻¹ with a gap of 0.2 mm, and the shear rate and the half power of the stress were plotted An approximate line by the least square method was drawn from the plot, and the viscosity at 1 s ⁻¹ was calculated.

[gasket]
The gasket of the present invention is a gasket obtained by irradiating the aforementioned gasket material of the present invention with active energy rays. As the energy ray, it is preferable to use ultraviolet rays from the viewpoints of operability, productivity and economy as described above. When ultraviolet rays are used, the gasket material preferably contains a photopolymerization initiator. 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. The irradiation time is usually preferably 10 seconds to 60 minutes, and the integrated light quantity is usually preferably 1,000 to 20,000 mJ / cm ² .

The curing method by irradiation of energy of the gasket material, preferably ultraviolet rays, can be appropriately selected according to the use of the obtained gasket.
Next, an example in which a gasketed member such as a HDD (hard disk drive) gasket of a computer is produced as the gasket will be described, and a preferable aspect of the manufacturing method will be described.

(Member with gasket)
A member with a gasket can be produced by applying the gasket material of the present invention to an adherend and curing it by irradiation with energy rays, preferably ultraviolet 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 are no particular restrictions 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 nickel-plated metal is preferred.
Examples of the member with gasket include a gasket for HDD, a seal for ink tank, a seal for liquid crystal device, and the like. Although the thickness of a gasket can be suitably selected according to a use, it is about 0.1-2 mm normally.

  The application of the gasket material to the adherend can be performed by any method using a coating liquid in which the temperature of the material is adjusted as necessary and adjusted to a constant viscosity, such as gravure coating, roll coating, Methods such as spin coating, reverse coating, bar coating, screen coating, blade coating, air knife coating, dipping, and dispensing can be used. After the gasket material is applied and molded, the coating layer is cured by irradiating energy rays, preferably ultraviolet rays, to obtain a member with a gasket.

(Application of gasket)
The gasket of the present invention is suitably used as a gasket for HDDs, etc., as well as a sealing material for ink tanks, a sealing material for various display devices, a sealing material for structures such as civil engineering and construction, packing for O-rings, etc. It can be used for applications such as members.
The present invention also provides a hard disk device using the gasket of the present invention.

EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples.
In addition, about the gasket material obtained by the Example and the comparative example, according to the following method, the surface adhesiveness in the room temperature (here 25 degreeC) after a high temperature process was evaluated, and the heat shock test was done.

(1. Surface tackiness)
Using the gasket material prepared in each example, a first-stage coating film was formed on a nickel-plated aluminum plate, and then the second-stage coating film was formed on the same gasket material. After forming to 1.1 mm, ultraviolet rays (using Fusion UV Systems Japan Co., Ltd. “Light Hammer 6”) are irradiated under the conditions of illuminance of 700 mW / cm ² and integrated light quantity of 10,000 mJ / cm ² , The coated film was cured to produce a gasketed member.
Next, the gasket of this gasketed member was compressed 40% with a nickel-plated aluminum plate and allowed to stand at 85 ° C. for 24 hours. Thereafter, the temperature was returned to room temperature (25 ° C.), the compression was released after 30 minutes, and the force to peel off the aluminum plate at this time was measured.
-Conditions for measuring peel force-
Measurement temperature: Room temperature (25 ° C)
Lifting speed: 50mm / min

(2. Heat shock test of gasket)
Using the gasket material prepared in each example, a first-stage coating film was formed on a nickel-plated aluminum plate, and then the second-stage coating film was formed on the same gasket material. After forming to 1.1 mm, ultraviolet rays (using Fusion UV Systems Japan Co., Ltd. “Light Hammer 6”) are irradiated under the conditions of illuminance of 700 mW / cm ² and integrated light quantity of 10,000 mJ / cm ² , The coated film was cured to produce a gasketed member.
Next, a pressure of 40% compression was applied to the gasket of the gasketed member, and 30 cycles at −40 ° C. and 1/30 cycle at 85 ° C. were performed for 100 cycles (comparative example) or 1000 cycles (implemented). Example) conducted and evaluated according to the following evaluation criteria.
A: No destruction was confirmed even after 1000 cycles.
○: Although no destruction was confirmed in 100 cycles,
Destruction was confirmed after 1000 cycles.
X: Destruction was confirmed after 100 cycles.

< Reference Examples 1 and 2, Examples 3 to 9 and Comparative Examples 1 to 10>
Each component shown in Table 1 was mixed to prepare a gasket material. Using the gasket material, a heat shock test was performed according to the above method. The results are shown in Table 1.

From the examples in Table 1, the gasket material of the present invention does not have much increased surface adhesion even after being placed in a high temperature environment. It is presumed that it was able to withstand the heat shock test. The gasket had sufficient leakage resistance at room temperature.
On the other hand, compared with the comparative example, the structure of the ester part of the component (B) is different, and the heat shock test for HDD gaskets cannot be endured, and the gaskets are not suitable for HDD gaskets. I understand.

  The gasket material of the present invention is useful for HDD gaskets, and is particularly useful for 2.5-inch HDD gaskets and also 3.5-inch HDD gaskets. In addition, it is also useful for applications such as ink tank sealing materials, sealing materials for various display devices, sealing materials for structures such as civil engineering and construction, packing such as O-rings, and vibration-proof members.

Claims (6)

(A) A material for a gasket containing an energy ray-curable liquid oligomer having a (meth) acryloyl group and (B) a (meth) acrylate monomer represented by the following general formula (1), the component (A) and The blending ratio [(A) :( B)] with the component (B)
A gasket material having a mass ratio of 80:20 to 20:80.

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a chain saturated aliphatic hydrocarbon group having 4 to 18 carbon atoms, and W represents an ethylene group or a propylene group. n represents an integer of 0 to 2.) Further, 0.1 to 10 parts by mass of a photopolymerization initiator, and an inorganic filler and / or an organic thixotropic agent are added to 100 parts by mass of the total amount of the components (A) and (B). 1-30 mass parts is contained , and the compounding ratio [(A) :( B)] of said (A) component and (B) component is 75: 25-20: 80 by mass ratio. The gasket material described in 1.   The gasket material according to claim 2, wherein the inorganic filler is silica.   A gasket obtained by irradiating the material according to claim 1 with active energy rays.   The gasket according to claim 4, which is used for a hard disk drive (HDD).   A hard disk device using the gasket according to claim 4.