JP5890634B2 - Gasket material, gasket and hard disk drive, and method for manufacturing gasket - Google Patents

Description

  The present invention relates to a gasket material that can be discharged by a dispenser at room temperature and has excellent shape retention after discharge, a gasket, a hard disk device using the gasket, and a method for manufacturing the gasket.

Computer hard disk drives (HDD; hard disk drives) are becoming more sophisticated and smaller in size, and have complex circuit configurations. Even a small amount of dust or moisture can cause damage, so it is practically dustproof. In addition, there is an increasing need for prevention of intrusion of moisture and moisture, 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

Currently, UV curable materials are the mainstream of materials used for HDD gaskets. In the molding method, a liquid material is filled in a syringe of a dispenser, which is extruded by air or a machine, discharged from a thin needle tip, and applied to a cover plate. Since it is still liquid after coating, it is cured (molded) by irradiating it with ultraviolet rays. As a method of extruding a material from a syringe, an air type is mainstream from the viewpoint of price and operation. When applying a material with an air-type dispenser, the following two items are important in blending the material.
(1) In order to discharge smoothly, the viscosity at the time of discharge should be below a certain value.
(2) In order to precisely control the dimensions, the shape is difficult to change between application and curing by ultraviolet irradiation.
Simply realizing the above items (1) and (2) includes a method of imparting thixotropy. However, considering the use of the mainstream air dispenser, gasket materials that can be discharged at an air pressure (usually about several hundred kPa) and that have a very small shape change after application have been known so far. Not. For this reason, currently, the following method (i) or (ii) is used.
(I) Adjusting the viscosity of the material to be high and placing importance on shape retention. And discharge property is ensured by heating a syringe.
(Ii) Adjust the viscosity of the material to a low level and place emphasis on the discharge performance. In order to ensure shape retention, an LED type small ultraviolet irradiation device is attached near the tip of the dispenser and semi-cured (temporarily consolidated) simultaneously with application.
However, the method (i) has a problem that a device for heating is required and it is necessary to wait until the temperature of the syringe becomes constant, resulting in poor production efficiency. In the method (ii), there is a problem that a set of LED type small ultraviolet irradiation devices is expensive.

  Therefore, an object of the present invention is to provide a gasket material that can be discharged by a dispenser at room temperature and has excellent shape retention after discharge, a gasket, a hard disk device using the gasket, and a method for manufacturing the gasket. It is to provide.

  As a result of intensive studies to solve the above problems, the present inventor is a material mainly composed of an energy ray-curable liquid oligomer having a (meth) acryloyl group and containing a (meth) acrylic monomer, which has a yield stress. It has been found that if the material has a viscosity in a high shear region within a specific range, it can be discharged with a dispenser at room temperature (for example, about 5 to 35 ° C.) and has excellent shape retention after discharge.

That is, the present invention relates to the following [1] to [11].
[1] A gasket material containing (A) an energy ray-curable liquid oligomer having a (meth) acryloyl group, (B) a (meth) acrylate monomer, and (C) an inorganic filler, and having a yield stress of 30 Pa or more. A gasket material having a viscosity (η ₁₀ ) at a shear rate of 10 s ⁻¹ of 100 Pa · s or less.
[2] The gasket material according to [1], wherein the content of the component (B) is 5 to 90 parts by mass with respect to 100 parts by mass of the component (A).
[3] The gasket material according to [1] or [2], wherein the content of the (C) inorganic filler is 3 to 20 parts by mass with respect to 100 parts by mass of the component (A).
[4] (B) (Meth) acrylate monomer is acryloylmorpholine, 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, isobornyl ( (Meth) acrylate, lauroxypolyethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxytripropylene Recall (meth) acrylate is at least one selected from methoxy polyethylene glycol (meth) acrylate and methoxy triethylene glycol (meth) acrylate, a gasket material according to any one of [1] to [3].
[5] The gasket material according to any one of [1] to [3], wherein the (B) (meth) acrylate monomer is represented by the following general formula (1).
(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.)
[6] The gasket material according to any one of [1] to [5], wherein (C) the inorganic filler is at least one selected from silica, alumina, titania, zirconia, and clay mineral.
[7] A gasket obtained by irradiating the material according to any one of [1] to [6] with active energy rays.
[8] The gasket according to [7], which is for a hard disk drive.
[9] A hard disk device using the gasket according to [8] above.
[10] (I) A step of applying the gasket material according to any one of [1] to [6] to an adherend with a dispenser, and (II) an uncoated portion applied in the step (I) Curing the cured gasket by irradiating active energy rays;
The manufacturing method of the gasket which has this.
[11] The method for producing a gasket according to [10], wherein the dispenser is an air-type dispenser having an air pressure of 0.02 to 0.7 MPa.

  Since the gasket material of the present invention has a low viscosity in a high shear region at room temperature, it can be applied by a dispenser (particularly an air-type dispenser), and the gasket can be easily produced. Further, since the gasket material of the present invention is excellent in shape retention after discharge, the gasket can be stably manufactured. The gasket of the present invention obtained from the material has high compression durability and can sufficiently withstand the heat shock test for HDD.

[Materials for gaskets]
The gasket material of the present invention contains an energy ray-curable liquid oligomer having a (meth) acryloyl group as the component (A), a (meth) acrylate monomer as the component (B), and an inorganic filler as the component (C). It is a material having a yield stress of 30 Pa or more and a viscosity (η ₁₀ ) at a shear rate of 10 s ⁻¹ of 100 Pa · s or less.
When the yield stress is less than 30 Pa, the shape retention is insufficient, and thus there is a need to use an expensive LED type small ultraviolet irradiation device. In this respect, the yield stress is preferably 32 Pa or more, more preferably 35 Pa or more, more preferably 40 Pa or more, still more preferably 45 Pa or more, and particularly preferably 55 Pa or more. When the viscosity (η ₁₀ ) at a shear rate of 10 s ⁻¹ exceeds 100 Pa · s, ejection by a dispenser (particularly an air-type dispenser) becomes impossible. From this viewpoint, η ₁₀ is preferably 95 Pa · s or less, more preferably 92 Pa · s or less, and still more preferably 80 Pa · s or less.
Note that the yield stress and η ₁₀ in the gasket material can be controlled by adjusting the types and addition amounts of the (A) component, the (B) component, and the (C) component.
Here, in this specification, η ₁₀ and yield stress are values calculated by the method described in the examples.
Hereinafter, each component of the gasket material of the present invention 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). In the present specification, “liquid” means liquid at normal temperature and normal pressure, and preferably has a weight average molecular weight of 5,000 to 40,000, more preferably 6,000 to 30,000. It is. 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 preferably about 2 to 6, more preferably 2 to 4, and still more 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 the (meth) acryloyl group may be used alone or in combination of two or more. When used for gasket applications, among the oligomers, from the viewpoint of performance and processability of the obtained gasket, bifunctional urethane-based (meth) acrylate oligomer, conjugated diene polymer (meth) acrylate oligomer, hydrogen Additive conjugated diene polymer (meth) acrylate oligomers are preferred. 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 (for example, 1,6-hexanediol, neopentyl glycol, 1,4-butanediol, 1,8-octanediol, 1,4-cyclohexanedimethanol, 2-methylpropanediol) , Dipropylene glycol, dibutylene glycol), or diols such as oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, hexahydrophthalic acid, etc. Can be obtained by transesterification of the polyester diol is the reaction product of a reaction product or ε- caprolactone and carboxylic acid.
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 conjugated diene polymer (meth) acrylate oligomer and the hydrogenated conjugated diene polymer (meth) acrylate oligomer have a weight average molecular weight of about 5,000 to 40,000 (more preferably 6,000 to 30,000). Oligomers are preferred. In addition, a number average molecular weight and a weight average molecular weight are values of standard polystyrene conversion measured by a gel permeation chromatography (GPC) method.

((B) (Meth) acrylate monomer)
In the gasket material of the present invention, a (meth) acrylate monomer is used as the component (B). By the combination of the component (B) and the component (A), the viscosity of the gasket material in a high shear region at normal temperature (about 5 to 35 ° C.) is reduced and can be discharged by a dispenser (particularly an air-type dispenser). Become.
As the (meth) acrylic monomer, a (meth) acrylic monomer having a molecular weight of less than 1,000 is preferable. For example, acryloylmorpholine, 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, isobornyl (meth) acrylate, lauroxypolyethylene glycol (meth) acrylate, methoxydipropylene Recall (meth) acrylate, methoxy tripropylene glycol (meth) acrylate, monofunctional (meth) acrylate monomers such as methoxypolyethylene glycol (meth) acrylate and methoxy triethylene glycol (meth) acrylate.
In addition, the (meth) acrylate monomer is preferably a (meth) acrylate monomer represented by the following general formula (1). In particular, by blending the gasket material with the (meth) acrylate monomer represented by the following general formula (1), the compression durability is high and the durability against the heat shock test for HDD gaskets is also high. A 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 durability in a heat shock test, and includes an ethylhexyl group, an isooctyl group (6-methylheptyl group), and n-dodecyl. A group (lauryl group), an isomyristyl group, and an isostearyl group are more preferable.
When R ² is a chain saturated aliphatic hydrocarbon group having 4 to 18 carbon atoms, a gasket that can sufficiently withstand the heat shock test for HDD gaskets tends to be obtained.
W is preferably an ethylene group from the viewpoint of availability.
(B) component (meth) acrylate monomer may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the component (B) is preferably 5 to 90 parts by mass, more preferably 5 to 80 parts by mass with respect to 100 parts by mass of the component (A). In particular, when the component (A) is a urethane-based (meth) acrylate oligomer, the content of the component (B) is preferably 5 to 50 parts by mass, more preferably 5 to 100 parts by mass of the component (A). -40 mass parts, More preferably, it is 5-35 mass parts. When component (A) is a conjugated diene polymer (meth) acrylate oligomer and / or a hydrogenated conjugated diene polymer (meth) acrylate oligomer, the amount of component (B) is 100 parts by weight of component (A). Is preferably 50 to 90 parts by mass, more preferably 60 to 90 parts by mass, and still more preferably 65 to 80 parts by mass.

((C) inorganic filler)
In the gasket material of the present invention, an inorganic filler is contained as the component (C). With the component (C), the shape retention of the gasket material is further improved. Examples of the inorganic filler include silica (SiO ₂ ), alumina, titania, zirconia, and viscous minerals. Examples of clay minerals include talc.
Among these, the component (C) is preferably silica or alumina, and more preferably silica, from the viewpoint of shape retention. More specifically, silica fine powder (for example, “Aerosil 90”, “Aerosil 300” manufactured by Nippon Aerosil Co., Ltd., “HDK N20” manufactured by Asahi Kasei Wacker Silicone Co., Ltd.) manufactured by Nippon Aerosil Co., Ltd.), etc. Can be mentioned.
The average particle size (average primary particle size) of the inorganic filler is preferably 5 to 200 nm, more preferably 5 to 100 nm, and even more preferably 5 to 50 nm, from the viewpoint of shape retention.
The content of the component (C) is preferably 3 to 20 parts by mass, more preferably 3 to 15 parts with respect to 100 parts by mass of the component (A), from the viewpoint of easy discharge with a dispenser and shape retention after discharge. Part by mass, more preferably 4 to 13 parts by mass.

  The gasket material of the present invention is an active energy ray curable material. As the active energy rays, ultraviolet rays; electron rays; ionizing radiations such as α rays, β rays, and γ rays can be used. However, ultraviolet rays are used from the viewpoints of operability, productivity, and economy. preferable. When ultraviolet rays are used, the gasket material of the present invention preferably contains a photopolymerization initiator (D) 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.

((D) 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 Acetophenone photopolymerization initiators such as 2-dichloroacetophenone, 2-benzyl-2- (dimethylamino) -4-morpholinobutylphenone, 2-hydroxy-2-methylpropiophenone, 4′-isopropyl-2- Alkylphenone photopolymerization initiators such as hydroxy-2-methylpropiophenone and 4′-dodecyl-2-hydroxy-2-methylpropiophenone; benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone and 2-ethylanthraquinone, 2-black Anthraquinone-based photopolymerization initiators such as anthraquinone; acylphosphine oxide-based photopolymerization initiators, and the like. Among these, alkylphenone photopolymerization initiators are preferable, propiophenone photopolymerization initiators are more 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 an 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 component (D) is contained in the gasket material of the present invention, the content thereof is usually preferably about 0.1 to 10 parts by mass, more preferably about 0.1 to 10 parts by mass with respect to 100 parts by mass of the component (A). 5 to 5 parts by mass, more preferably 0.5 to 3 parts by mass. Moreover, a well-known photosensitizer can also be used together with the said photoinitiator.

(Optional component)
In the gasket material of the present invention, an organic thixotropic agent, a coupling agent, an antioxidant (anti-aging agent), a photostabilization as an optional component as necessary, as long as the object of the present invention is not impaired. Agents, carbodiimides, etc., fatty acids such as stearic acid; fatty acid metal salts such as calcium stearate; fatty acid amides such as stearic acid amide; fatty acid esters; internal mold release agents such as polyolefin wax and paraffin wax; process oil Softeners such as, coloring agents, leveling agents and the like. The gasket material of the present invention is basically solvent-free, but various solvents may be blended as necessary.
Hereinafter, these optional components will be described.

(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 individually by 1 type and may be used in combination of 2 or more type.
When the organic thixotropic agent is added to the gasket material of the present invention, the content thereof is usually preferably 30 parts by mass or less, more preferably 15 parts by mass or less, relative to 100 parts by mass of the component (A). More preferably, it is 10 parts by mass or less.

(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 the coupling agent is contained in the gasket material of the present invention, the content is usually preferably about 0.1 to 20 parts by mass, more preferably 1 to 15 parts per 100 parts by mass of the component (A). Part by mass, 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.
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 contained in the gasket material of the present invention, the content is appropriately selected according to the type, but is usually preferably 0.01 to 100 parts by mass of component (A). 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 ] Butyl malonate, 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-pipe 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-tetra Methyl-4-piperidinyl) pyrrolidine-2,5-dione, 2,2,4,4-tetramethyl-7-oxa-3,20-diazadispiro [5.1.1.12] heneicosane- 1-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 contained in the gasket material of the present invention, the content thereof is appropriately selected according to the type thereof, but is preferably 0.01 to 100 parts by mass of component (A). 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 carbodiimides are included in the gasket material of the present invention, the content is appropriately selected according to the type, but is preferably 0.01 to 5 with respect to 100 parts by mass of component (A). Part by mass, more preferably 0.1 to 3 parts by mass.

(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.

[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 the case of producing a gasketed member such as a HDD HDD gasket of a computer will be given and a preferable aspect of the manufacturing method will be described.

[Gasket manufacturing method]
(I) The process of apply | coating the gasket material of this invention to a to-be-adhered body with a dispenser, (II) The process of irradiating an active energy ray and hardening | curing the uncured gasket apply | coated in the said process (I). ,
By using a method for manufacturing a gasket having the above, a member with a gasket can be manufactured easily and stably.
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.
As the dispenser, an air-type dispenser is simple and preferable. The air pressure of the air-type dispenser is usually about 200 to 1,000 kPa, and it is preferable that the gasket material can be discharged at an air pressure of about 200 to 600 kPa.
Note that a gasket having a multistage structure can be manufactured by repeating the step (I).

  The gasket material can be applied to the adherend by a method other than a method using a dispenser (dispensing). The temperature of the material is adjusted as necessary, and a coating liquid adjusted to a constant viscosity is used. It can be done in any way. For example, gravure coating, roll coating, spin coating, reverse coating, bar coating, screen coating, blade coating, air knife coating, dipping, and the like can be used. However, the dispenser is the most effective feature of the present invention. This method is used.

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 material for gaskets obtained in the Example and the comparative example, the yield stress and the viscosity (η ₁₀ ) at a shear rate of 10 s ⁻¹ were measured according to the following method. Moreover, according to the following evaluation criteria, the ease of discharge from a dispenser and the shape retention after discharge were evaluated.

(Measurement of viscosity and yield stress)
η ₁₀ was measured using a rheometer "RS-600" (the Haake Co., Ltd.). As a sensor, a cone plate having a diameter of 35 mm and θ = 2 ° was used. First, the gasket material was adjusted to 25 ° C., and reset by measuring for 60 seconds at a gap of 0.111 mm and a shear rate of 10 s ⁻¹ (Step 1). Next, the shear stress was measured for 20 seconds each in the order of shear rates 1 s ⁻¹ , 2 s ⁻¹ , 3 s ⁻¹ ,..., 10 s ⁻¹ (Step 2: forward path). Furthermore, the shear stress was measured for 20 seconds each in the order of shear rates 10 s ⁻¹ , 9 s ⁻¹ , 8 s ⁻¹ ,..., 1 s ⁻¹ (Step 3: return path). Using the least squares method from the Casson plot in which the shear rate and the shear stress 1/2 power (vertical axis: shear power 1/2 power, horizontal axis: shear power 1/2 power) in Step 3 (return path) are plotted An approximate line was drawn to calculate the viscosity (η ₁₀ ) at 10 s ⁻¹ . Moreover, the square of the intersection of the approximate line and the vertical axis was calculated as the yield stress.

(Evaluation of easy discharge from dispenser)
With a dispenser having a syringe needle diameter of 0.92 mm, a material that could be discharged at 25 ° C. with an air pressure of 400 kPa or less was indicated as “◯”, and a material that could not be discharged was indicated as “X”.
(Evaluation of shape retention after discharge)
The material was discharged with a syringe needle diameter of 0.92 mm at 25 ° C. and an air pressure of 400 kPa or less. Based on the height (h ₀ ) of the uncured gasket immediately after discharge (measured within 30 seconds) as a reference, the rate of change of the height (h ₁ ) of the uncured gasket 3 minutes after discharge ([(h ₀₋ h ₁ ) / h ₀ ] × 100) was investigated. A material having a change rate of less than 5% was indicated by “◯”, and a material having a change rate of 5% or more was indicated by “X”.

<Production Example 1> Method for Producing Hydrogenated SBR Diacrylate Oligomer In a reactor with an internal volume of 7 L purged with argon, 1.90 kg of dehydrated and purified cyclohexane, 2 kg of hexane solution of 22.9% by mass of 1,3-butadiene, 20 After adding 0.573 kg of a 0.02 mass% styrene cyclohexane solution and 130.4 ml of a 1.6 mol / L hexane solution of 2,2-di (tetrahydrofuryl) propane, a 0.5 mol / L dilithium polymerization initiator is added. 108.0 ml was added to initiate the polymerization. The mixture was heated to 50 ° C., polymerized for 1.5 hours, 108.0 ml of a 1 mol / L ethylene oxide cyclohexane solution was added, and the mixture was further stirred for 2 hours, and then 50 ml of isopropyl alcohol was added.
A hexane solution of the obtained copolymer is precipitated in isopropyl alcohol and sufficiently dried to give a styrene butadiene rubber having a hydroxyl group at the molecular end (styrene content: 20% by mass, weight average molecular weight 18,000, molecular weight distribution). 1.15) was obtained. In addition, the weight average molecular weight was calculated | required by standard polystyrene conversion using GPC method.

(Hydrogenation treatment)
120 g of styrene butadiene rubber having a hydroxyl group at the molecular end obtained above was dissolved in 1 L of sufficiently dehydrated and purified hexane, and then nickel naphthenate, triethylaluminum and butadiene prepared in separate containers in advance [1: 3: 3 (molar ratio)] was prepared so that the amount of nickel was 1 mol with respect to 1,000 mol of the butadiene-derived structural unit of the styrene-butadiene rubber. Hydrogen was added under pressure at 2.758 MPa (400 psi) to the sealed reaction vessel, and a hydrogenation reaction was performed at 110 ° C. for 4 hours.
Thereafter, the catalyst residue was extracted and separated with ³ mol / m ³ hydrochloric acid, and further centrifuged to separate the catalyst residue by sedimentation. Then, a hydrogenated styrene butadiene rubber having a hydroxyl group at the molecular end is precipitated in isopropyl alcohol and further sufficiently dried to obtain a hydrogenated styrene butadiene rubber having a hydroxyl group at the molecular end (styrene content 20 mass%, weight average molecular weight). 16,500, hydrogenation rate 98%, molecular weight distribution 1.1) were obtained.
(Introduction of active energy ray-curable functional groups to molecular terminals)
The above-obtained hydrogenated styrene butadiene rubber having a hydroxyl group at the molecular terminal is dissolved in cyclohexane and stirred at 40 ° C., 2-acryloyloxyethyl isocyanate (“Karenz (registered trademark) AOI”, manufactured by Showa Denko KK ) Was slowly added dropwise, followed by further stirring for 4 hours, and then crystals were precipitated in isopropyl alcohol to obtain a terminal-modified hydrogenated styrene butadiene rubber (hydrogenated SBR diacrylate oligomer).

<Examples 1-15 and Comparative Examples 1-4>
Each component shown in Table 1 was mixed to prepare a gasket material. Using the gasket material, the yield stress and the viscosity (η ₁₀ ) at a shear rate of 10 s ⁻¹ were measured according to the above method. The results are shown in Table 1.

* 1: Light tack PUA-KH32M (manufactured by Kyoeisha Chemical Co., Ltd.)
* 2: Hydrogenated SBR acrylate oligomer produced in Production Example 1 * 3: Light acrylate EHDG-AT (manufactured by Kyoeisha Chemical Co., Ltd.), see below * 4: Light acrylate IM-A (manufactured by Kyoeisha Chemical Co., Ltd.), see below * 5: Light acrylate PO-A (manufactured by Kyoeisha Chemical Co., Ltd.), see below * 6: IBXA (manufactured by Osaka Organic Chemical Industry Co., Ltd.), see below * 7: ACMO (manufactured by Kojin Co., Ltd.), acryloylmorpholine, Reference * 8: HDK N20 (Asahi Kasei Wacker Silicone Co., Ltd.)
* 9: Aerosil 300 (manufactured by Nippon Aerosil Co., Ltd.)
* 10: Aerosil 90 (manufactured by Nippon Aerosil Co., Ltd.)
* 11: Aeroxide Alu C (Nippon Aerosil Co., Ltd.)
* 12: DAROCUR 1173 (manufactured by BASF Japan Ltd.)
* 13: IRGACURE 369 (manufactured by BASF Japan Ltd.)

From Table 1, it can be seen that the gasket material of the present invention can be discharged by a dispenser at 25 ° C., and the uncured gasket after discharge is excellent in shape retention. On the other hand, when the yield stress was less than 30 Pa (Comparative Examples 1 and 3), the shape retention after discharge was poor. Further, when the viscosity (η ₁₀ ) at a shear rate of 10 s ⁻¹ exceeds 100 Pa · s (Comparative Examples 2 and 4), it could not be discharged using a dispenser at 25 ° C.

  The gasket material of the present invention is useful for HDD gaskets. Besides, a sealant for ink tanks, a sealant for various display devices, a sealant for structures such as civil engineering and architecture, a packing such as an O-ring, It is also useful for applications such as vibration isolation members.

Claims (9)

(A) An energy ray curable liquid oligomer having a (meth) acryloyl group, (B) a (meth) acrylate monomer, and (C) a gasket material containing an inorganic filler,
The (B) (meth) acrylate monomer is a compound represented by the following formula

Of is any further yield stress is at least 35 Pa, and the gasket material is the viscosity at a shear rate of ^{10s -1 (η} ₁₀₎ is less than 100 Pa · s.   The material for gaskets of Claim 1 whose content of the said (B) component is 5-90 mass parts with respect to 100 mass parts of said (A) component.   (C) The material for gaskets of Claim 1 or 2 whose content of an inorganic filler is 3-20 mass parts with respect to 100 mass parts of said (A) component.   (C) The material for gaskets in any one of Claims 1-3 whose inorganic filler is at least 1 sort (s) selected from a silica, an alumina, a titania, a zirconia, and a clay mineral.   The gasket obtained by irradiating an active energy ray to the material in any one of Claims 1-4.   The gasket according to claim 5, which is used for a hard disk drive.   A hard disk device using the gasket according to claim 6. (I) The process of apply | coating the gasket material in any one of Claims 1-4 to a to-be-adhered body with a dispenser, (II) The uncured gasket apply | coated in the said process (I) is active energy. A process of irradiating and curing a wire,
The manufacturing method of the gasket which has this.   The method for manufacturing a gasket according to claim 8, wherein the dispenser is an air-type dispenser having an air pressure of 0.02 to 0.7 MPa.