JP2001302874A - Resin composition, gasket material and metal-integrated gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition having excellent rubber elasticity, high oil retention a low hardness and a small compression set, exhibiting excellent adhesiveness to metals and suitable for a gasket material, especially a material for a metal-integrated gasket. SOLUTION: The objective thermoplastic elastomer composition is composed of (a) 100 pts.wt. of a hydrogenated block copolymer produced by the hydrogenation of a block copolymer composed of at least one polymer block composed mainly of a vinyl aromatic compound and at least one polymer block composed mainly of a conjugated diene compound, (b) 100-200 pts.wt. of a softening agent for non-aromatic rubber and (c) 10-50 pts.wt. of a modified polyolefin resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasket having excellent properties such as excellent rubber elasticity, good oil retention, low hardness and low compression set, and excellent adhesion to metal. The present invention relates to a resin composition suitable for a material, particularly a gasket material for a metal-integrated gasket.

[0002]

2. Description of the Related Art In recent years, electronic devices such as computers have been improved in performance and miniaturization, and have complicated circuit structures. Even small amounts of dust can cause obstacles. The use of gaskets to prevent dust intrusion is common practice. Such gaskets are often used in the form of a metal-integrated gasket in which a gasket material made of a low-hardness thermoplastic elastomer is injection-molded on a metal part such as a case lid. As a method of integrating a metal component and a low-hardness thermoplastic elastomer, conventionally, the following methods have been employed, but all of these methods require complicated production steps and require high production costs. . In the part where the elastomer of the metal part surface is injection molded,
A method of applying an adhesive in advance A method of providing a through-hole or a groove in advance in a part of a metal part where an elastomer is to be injection-molded and mechanically locking the injection-molded part In view of the drawbacks of these conventional methods, a metal part is used. There is a demand for a low-hardness thermoplastic elastomer which has excellent adhesion to a metal component and can be retained and integrated simply by injecting it onto the surface of a metal component without going through a complicated process.

[0003]

SUMMARY OF THE INVENTION The present invention provides a rubber composition having excellent rubber elasticity, good oil retention, low hardness, excellent settability, and low compression set under such circumstances. An object of the present invention is to provide a resin composition which is excellent in performance required as a gasket material, has excellent adhesiveness to metal, and is suitable for a material for a metal-integrated gasket.

[0004]

Means for Solving the Problems The present inventors have previously described a rubber elasticity comprising a hydrogenated block copolymer having specific physical properties and proportions, a softener for a non-aromatic rubber and a polyolefin resin. Excellent oil retention, low hardness,
A gasket material having excellent settability and a small compression set was proposed (Japanese Patent Application No. 11-344879), but as a result of intensive studies to achieve the above object, the polyolefin resin of the prior invention was obtained. It has been found that the purpose can be achieved by using a modified polyolefin resin instead. The present invention has been completed based on such findings.

That is, the present invention relates to (a) a block copolymer comprising at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound. A hydrogenated block copolymer obtained by addition, having a weight average molecular weight of 200,000 or more, and a polymer block mainly composed of a vinyl aromatic compound being styrene; 100% by weight of a hydrogenated block copolymer having a polystyrene content ratio of 20 to 40% by weight, and (b) softening for a non-aromatic rubber having a kinematic viscosity at 40 ° C. of 300 mm ² s ⁻¹ or more. A thermoplastic elastomer composition comprising 100 to 200 parts by weight of an agent and (c) 10 to 50 parts by weight of a modified polyolefin resin, the hardness of which is JIS K62. It is a resin composition having a compression set of 50% or less after standing at 70 ° C for 22 hours under 25% compression measured by a type A durometer according to JIS 53 and at 25% compression measured according to JIS K6262.
The present invention also includes a gasket material made of the resin composition of the present invention, a metal-integrated gasket formed by using the gasket material, and a gasket for a hard disk made of the metal-integrated gasket. .

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The hydrogenated block copolymer of the component (a) in the resin composition of the present invention comprises at least one polymer block mainly composed of a vinyl aromatic compound,
A hydrogenated block copolymer obtained by hydrogenating a block copolymer consisting of at least one polymer block mainly composed of a conjugated diene compound, having a weight average molecular weight of 200,000 or more, A polymer block mainly composed of a group III compound is styrene, and the polystyrene content in the hydrogenated block copolymer is 20 to 40% by weight. For example, polybutadiene and polystyrene And a block copolymer of polyisoprene and polystyrene,
Alternatively, it can be obtained by hydrogenating a block copolymer of polybutadiene or an ethylene-butadiene random copolymer and polystyrene. Particularly, styrene-butadiene-styrene block copolymer, styrene-isoprene-
A styrene block copolymer or a hydrogenated block copolymer obtained by hydrogenating a styrene-butadiene / isoprene-styrene block copolymer is preferable.

The hydrogenated block copolymer of the component (a) in the present invention is specifically a diblock copolymer of crystalline polyethylene and polystyrene, styrene-ethylene /
Butylene-styrene triblock copolymer (SEB
S), triblock copolymer of styrene-ethylene / propylene-styrene (SEPS), styrene-ethylenepropylene / ethylenebutylene-styrene block copolymer and the like.
EPS or styrene-ethylene propylene / ethylene butylene-styrene block copolymer is preferred. These hydrogenated block copolymers have a weight average molecular weight of 200,000 or more, and particularly preferably 400,000 to 700,000. When the weight average molecular weight is less than 200,000, there is a disadvantage that the bleeding of the softening agent is remarkable, the compression set is large, and it cannot withstand practical use. The content of the (amorphous) styrene block in the hydrogenated block copolymer is 20 to 40% by weight.
It is. If the content is less than 20% by weight, the compression set becomes large, and if it exceeds 40% by weight, the hardness becomes too high.

The glass transition temperature (Tg) of the (amorphous) styrene block is preferably 60 ° C. or higher, more preferably 80 ° C. or higher. As the polymer at the portion connecting the amorphous styrene blocks at both ends, an amorphous polymer is also preferable. For example, hydrogenated products such as ethylene-butylene copolymer, butadiene polymer, and isoprene polymer are preferable. And a block or random copolymer thereof. In addition, these hydrogenated block copolymers are mainly used alone, but two or more kinds may be blended and used. 2 with different molecular weight and styrene content
By blending more than one type of copolymer, the fluidity during molding can be improved. These hydrogenated block copolymers,
Kuraray's Septon (trade name), Shell Chemical Co., Ltd.
It can be easily obtained from commercially available products such as Clayton G (trade name) manufactured by Asahi Kasei Corporation and TUFTEC (trade name).

The non-aromatic rubber softener (b) in the resin composition of the present invention is used to reduce the hardness of the resin composition of the present invention, and has a kinematic viscosity at 40 ° C. Is 300 mm ² s ⁻¹ or more. If the kinematic viscosity at 40 ° C. of the softener is less than 300 mm ² s ⁻¹ , the composition loses weight and bleeds significantly due to volatilization, resulting in inconvenience that it cannot withstand actual use. This kinematic viscosity is 300 ° C. at 40 ° C. from a practical and manufacturing point of view.
It is preferably from ¹ to 10,000 mm ² s ⁻¹ , and
00-5000 mm < ² > s < ^-1 > is preferable. Further, from the viewpoint of molecular weight, the weight average molecular weight is less than 20,000, especially 1
Those having 0000 or less, especially 5000 or less are preferred. As such a softening agent, usually, a liquid or liquid at room temperature is suitably used. The softener having such properties can be appropriately selected from various softeners for non-aromatic rubbers such as mineral oils, vegetable oils, and synthetic oils. Here, mineral oils include process oils such as naphthenic and paraffinic oils, and vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, nagiko oil, peanut oil, Wood wax, pine oil, olive oil, and the like. Above all,
In particular, one or more selected from mineral oil-based paraffinic oils, naphthenic oils, and synthetic polyisobutylene-based oils, having a number average molecular weight of 450
Those having a molecular weight of ~ 5000 are preferred.

These softeners may be used alone or as a mixture of two or more as long as they have good compatibility with each other. The compounding amount of these softeners is 100 to 200 parts by weight, preferably 100 to 150 parts by weight, based on 100 parts by weight of the component (a). If the amount is less than 100 parts by weight, it is not possible to achieve a sufficiently low hardness, and the flexibility of the thermoplastic material may be insufficient. If the amount exceeds 200 parts by weight, the softener tends to bleed, and This causes the mechanical strength of the plastic material to decrease. The amount of the softener is appropriately selected from the above range according to the molecular weight of the hydrogenated block copolymer of the component (a) and the type of other components added to the hydrogenated block copolymer. Is preferred. These softeners include Diana Process Oil Series (trade name) manufactured by Idemitsu Kosan Co., Ltd., Sambar Series (trade name) and Sunsen Series (trade name) manufactured by Nippon Sun Oil Co., Ltd., and Lucant manufactured by Mitsui Chemicals, Inc. It can be easily obtained from those commercially available as a series (product name).

The modified polyolefin resin of the component (c) in the resin composition of the present invention is blended to improve processability and heat resistance and to improve adhesion to metal. As the modified polyolefin resin, those mainly composed of polypropylene are preferable, and isotactic polypropylene, a copolymer of propylene with a small amount of other α-olefin (for example, propylene-ethylene copolymer, Propylene / 4-methyl-
1-pentene copolymer). When a copolymer of isotactic polypropylene is used as the polyolefin resin, its MFR (JIS
K7210, at 230 ° C. under a load of 2.16 kg) of at least 0.1 g / 10 min, especially at least 0.5 g / 10 min can be suitably used.

The modified polyolefin resin is obtained by polymerizing a polymerizable compound having a functional group on such a polyolefin resin. In particular, a functional group having an absorption band at a wave number of 1500 to 2000 cm ^-1 in an infrared absorption spectrum is used. Is preferred. In other words, according to the “Polymer Analysis Handbook” (Kinokuniya Shoten), the “characteristic absorption band” specific to polymer compositions is used as “application to qualitative analysis” of infrared analysis of polymer materials such as plastics and rubber. It has been found that there is a characteristic absorption band in the functional group of the polymer in the range of 1550 to 1950 cm ^-1 . For example, the absorption due to “carbonyl groups such as ketones, aldehydes and amides” “appears around 1700 cm ⁻¹ ”, and “in the case of esters, acid chlorides and acid anhydrides,
Absorption appears around 1850-1725 cm ^-1 on the higher wavenumber side, "and" 1610-10
It is described that there is an absorption band at "1550 cm ^-1 ". Furthermore, it is also described in detail that there is an absorption characteristic of "carbonyl in the 1750-1720 cm ^-1 region". Also,
With regard to the infrared absorption spectrum of polypropylene grafted with maleic anhydride, in particular, "C = O of maleic anhydride
Stretching vibrations appear around 1785 and 1860 cm ^-1 ". On the other hand, the infrared absorption spectrum of pure polypropylene described in the handbook has no infrared absorption in this region (1550 to 1950 cm ^-1 ). The present inventors have found that as a result of earnest research, 150
It has been found that a polyolefin-based resin having a functional group (maleic anhydride, acrylic acid, amide, carboxylate, etc.) having an absorption band in the range of 0 to 2000 cm ^-1 is preferable as the component (c).

The functional group having an absorption band in the range of 1500 to 2000 cm ^-1 is more preferably an unsaturated carboxylic acid, particularly one in the form of maleic anhydride or acrylic acid, and is an acid ester. It shows better adhesion than the ones. Examples of the polyolefin-based resin having such a functional group include, for example, Nuclell series (trade name) manufactured by Mitsui DuPont Polychemicals Co., Ltd., Umex series (trade name) manufactured by Sanyo Chemical Co., Ltd., and Exxon Chemical Co., Ltd. Commercially available products such as the Exeller series (trade name), the Polybond series (trade name) manufactured by Uniroyal Corporation, and the Admar series (trade name) manufactured by Mitsui Chemicals, Inc. can be used. The conversion rate (% by weight: 100 parts by weight of the modifier used relative to 100 parts by weight of polypropylene) is preferably 1% by weight or more in order to obtain sufficient adhesiveness. The amount of component (c) is 10 to 50 parts by weight, preferably 10 to 30 parts by weight, per 100 parts by weight of component (a). If the amount is less than 10 parts by weight, the required adhesiveness cannot be obtained. If the amount exceeds 50 parts by weight, the hardness of the obtained thermoplastic material becomes too high. The resin composition of the present invention comprising these components (a), (b) and (c) has a hardness of 50 ° or less with a type A durometer in accordance with JIS K6253,
70 under 25% compression measured according to K6262.
The compression set after being left at 22 ° C. for 22 hours is 50% or less, and if these conditions are not satisfied, it is not suitable for use as a gasket material.

In the resin composition of the present invention, a polystyrene resin can be used in combination with the component (c) in order to improve the processability and heat resistance of the material. As the polystyrene resin, any one obtained by a radical polymerization method or an ionic polymerization method can be suitably used as long as it is obtained by a known production method. The number average molecular weight of the polystyrene resin can be preferably selected from the range of 5,000 to 500,000, more preferably from 10,000 to 200,000,
The molecular weight distribution [the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn)] is preferably 5 or less. Examples of the polystyrene resin include polystyrene, a styrene-butadiene block copolymer having a styrene unit content of 60% by weight or more, rubber-reinforced polystyrene, poly-α-methylstyrene, polypt-butylstyrene, and the like. May be used alone or in combination of two or more. Further, a copolymer obtained by polymerizing a mixture of monomers constituting these polymers can also be used. In the resin composition of the present invention, when a polystyrene resin is used in combination with the component (c), the hardness of the obtained material tends to be higher than when no polystyrene resin is used. Therefore, the hardness of the obtained thermoplastic material can be adjusted by selecting these compounding ratios. In this case, the modified polyolefin resin /
The ratio of the polystyrene resin is preferably selected from the range of 95/5 to 5/95 (weight ratio).

In the present invention, in order to obtain a resin composition containing a large amount of a softening agent and a smaller amount of a high molecular weight organic material, the softening agent to be used and the conjugated diene compound constituting the hydrogenated block copolymer are used. Solubility parameter value δ = (ΔE / V) ^1/2 (ΔE =
(Molar evaporation energy, V = molar volume) is less than 3.0,
It is preferable to select both components so as to be preferably 2.5 or less, more preferably 1.0 or less. If this difference exceeds 3.0, the compatibility of the two materials makes it difficult to retain a large amount of the softening agent, which hinders the lowering of the hardness of the obtained resin composition, and that the softening agent tends to bleed. Is not preferred. The resin composition of the present invention may optionally contain a polyphenylene ether resin for the purpose of improving compression set. The polyphenylene ether resin used here is a homopolymer composed of a repeating unit represented by the following general formula or a copolymer containing the repeating unit.

[0016]

Embedded image

(In the formula, R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom or a hydrocarbon group.) As the polyphenylene ether resin, known ones can be used. Specifically, poly (2,6-dimethyl-1,4-phenylene ether), poly (2-methyl-6-ethyl-1,4-phenylene ether), poly (2,6-diphenyl-1, 4-phenylene ether), poly (2-methyl-6-phenyl-1,4-phenylene ether), poly (2,6-dichloro-1,4-
Phenylene ether), and 2,6-
Dimethylphenol and monovalent phenols (for example,
2,3,6-trimethylphenol or 2-methyl-6
A polyphenylene ether copolymer such as a copolymer with (butylphenol) can also be used. Above all, poly (2,6-dimethyl-1,4-phenylene ether)
And a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol, and more preferably poly (2,6-dimethyl-1,4-phenylene ether).

The compounding amount of the polyphenylene ether resin is as follows:
It can be suitably selected in the range of 10 to 250 parts by weight with respect to 100 parts by weight of the total amount of the components (a), (b) and (c). If the amount is more than 250 parts by weight, the hardness of the resin composition may increase. If the amount is less than 10 parts by weight, the effect of improving the compression set obtained by compounding is insufficient.

Further, the resin composition of the present invention includes clay,
Diatomaceous earth, talc, barium sulfate, calcium carbonate, magnesium carbonate, metal oxides, flaky inorganic additives such as mica, graphite, aluminum hydroxide, various metal powders, glass powders, ceramic powders, granular or powdered polymers, etc. And various kinds of natural or artificial short fibers and long fibers (for example, glass fiber, metal fiber, other various polymer fibers, etc.) and the like. Also,
The weight can be reduced by blending a hollow filler, for example, an inorganic hollow filler such as a glass balloon, or an organic hollow filler made of polyvinylidene fluoride, a polyvinylidene fluoride copolymer, or the like. Further, in order to improve various physical properties such as weight reduction, it is possible to mix various foaming agents, and it is also possible to mechanically mix gas during mixing or the like.

As other additives, if necessary,
Various tackifiers such as flame retardants, antibacterial agents, hindered amine light stabilizers, ultraviolet absorbers, antioxidants, coloring agents, coumarone resins, coumarone-indene resins, phenol terpene resins, petroleum hydrocarbons, rosin derivatives, etc. Fire), Rheosummer B (trade name: manufactured by Riken Vinyl Co., Ltd.)
Various adhesive elastomers, such as HYBRA (trade name: Kuraray Co., a block copolymer in which polystyrene blocks are linked to both ends of a vinyl-polyisoprene block), Norex (trade name, manufactured by Zeon Corporation, norbornene) Other thermoplastic elastomers or resins such as polynorbornene obtained by ring-opening polymerization can be used in combination.

The method for producing the resin composition of the present invention is not particularly limited, and a known method can be applied. For example, the above-mentioned components and optionally used additive components are melt-mixed using a heating kneader, for example, a single-screw extruder, a twin-screw extruder, a roll, a Banbury mixer, a pravender, a kneader, a high-shear mixer, or the like. Kneading, and further, if desired, adding a crosslinking agent such as an organic peroxide, a crosslinking aid, or the like, or mixing these necessary components at the same time, and heat-melting and kneading to easily produce. . A thermoplastic material prepared by kneading a high-molecular organic material and a softener is prepared in advance, and this material is further mixed with one or more high-molecular organic materials of the same type or different types used here. It can also be manufactured.
Further, in the resin composition of the present invention, crosslinking may be performed by adding a crosslinking agent such as an organic peroxide, a crosslinking aid, or the like.

The crosslinking agent that can be added for partial crosslinking is preferably an organic peroxide. Specifically, for example, 2,5-dimethyl-2,5-di (t
-Butylperoxy) -hexane; 2,5-dimethyl-
2,5-di (benzoylperoxy) -hexane; t-
Butylperoxybenzoate; dicumyl peroxide; t-butylcumyl peroxide; diisopropylbenzohydroperoxide; 1,3-bis- (t-
Butylperoxyisopropyl) -benzene; benzoyl peroxide; 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane and the like, and useful crosslinking aids include, for example, Divinylbenzene, trimethylolpropane triacrylate, ethylene dimethacrylate, diallyl phthalate,
Quinone dioxime, phenylene bismaleimide, polyethylene glycol dimethacrylate and the like.
These organic peroxides and crosslinking assistants can be used arbitrarily to adjust the degree of crosslinking in the range of 0.1 to 5 parts by weight, based on 100 parts by weight of the whole compounding material. These organic peroxides and crosslinking assistants may be used in combination of two or more, if necessary. When an unsaturated silane compound is used as a crosslinking aid,
Further, crosslinking can be promoted by contact with water in the presence of a silanol condensation catalyst.

The resin composition of the present invention thus obtained comprises:
It can be molded into a desired shape by a known method such as injection molding or extrusion molding and used as a gasket material. In particular, because of its excellent adhesion to metal, a metal-integrated gasket integrated with a metal component such as a case lid is provided on the surface of the metal component by applying an adhesive in advance or forming through holes or grooves. It can be manufactured without any. The resin composition of the present invention is particularly suitably used as a gasket material for a hard disk drive that requires high dustproofing properties. Can be suitably used.

[0024]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The evaluation of physical properties in the following Examples and Comparative Examples was performed by the following methods. (1) Hardness Measured with a type A durometer according to JIS K6253. (2) Compression set In accordance with JIS K6262, 70 ° C under 25% compression,
After standing for 22 hours, the compression set was measured. (3) Adhesion to Metal As shown in FIG. 1, a metal-integrated gasket in which a gasket 2 was formed on an aluminum plate 1 was formed. In other words, the pre-pressed 1
A rectangular aluminum plate having a side of 25 mm × 40 mm and a thickness of 1 mm was installed, and the resin composition was sprayed on the surface thereof at an injection temperature of 2 mm.
Inject under conditions of 00 ° C and injection cycle 20 seconds, width 1m
A □ -shaped resin molded body (gasket) having a length of 1 mm, a side of 15 mm × 30 mm and a height of 1 mm was formed on an aluminum plate. The following criterion was evaluated according to the state of the resin molded body at the time of demolding (operation of opening the mold and taking out the molded product) in the injection operation. ：: The resin molded product is not peeled off from the aluminum plate at the time of demolding. ：: At the time of demolding, there is a probability of 50% or less, but the resin molded product may peel off from the aluminum plate. ×: The resin molded body peeled off from the aluminum plate or deviated from a predetermined position during demolding.

Examples 1 to 4 and Comparative Examples 1 and 2 (1) Preparation of thermoplastic material Each component having the composition shown in Table 1 was sufficiently kneaded to prepare a sample of a thermoplastic resin. An evaluation was performed.
As a result, as is clear from Table 1, the thermoplastic resins of Examples 1 to 3 had good adhesion to metal, but the thermoplastic resin of Example 4 had somewhat poor adhesion to metal. ,
It was observed that the thermoplastic resins of Comparative Examples 1 and 2 had low adhesion to metal and were not practical.

[0026]

[Table 1]

A-1: SEPS having a weight average molecular weight of 350,000 and a polystyrene content of 30% by weight or more A-2: SEPS B-1 having a weight average molecular weight of 150,000 and a polystyrene content of 30% by weight or more : Paraffin oil having a kinematic viscosity at 380 mm ² s ^-1 at 40 ° C. C-1: Maleic anhydride-modified polypropylene having a modification rate of 5% by weight C-2: Maleic anhydride-modified polypropylene having a modification rate of 0.5% by weight C- 3: Unmodified polypropylene

[0028]

According to the present invention, the resin composition has excellent rubber elasticity, good oil retaining properties, low hardness, and low compression set, and has excellent adhesiveness to metal. A gasket material, in particular, a metal-integrated gasket, which can be manufactured by ordinary injection molding without going through complicated steps such as applying an adhesive on a metal component surface in advance and providing through holes and grooves. It is.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a metal-integrated gasket manufactured for an adhesion test to metal.

[Explanation of symbols]

 1: Aluminum plate 2: Gasket (resin molding)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yasushi Imai 150-7-210, Kashio-cho, Totsuka-ku, Yokohama-shi, Kanagawa-ken (72) Inventor Tadashi 2-20-24 Komachi, Kamakura-shi, Kanagawa F-term (reference) 3J040 BA01 EA16 FA06 HA05 HA09 HA21 4J002 AE05X BB20Y BB21Y BP01W FD010 FD140 GJ02 GM00

Claims (7)

[Claims] 1. A method comprising hydrogenating a block copolymer comprising (a) at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound. Is a hydrogenated block copolymer having a weight average molecular weight of 200,000 or more, a polymer block mainly composed of a vinyl aromatic compound is styrene, and the polystyrene occupies in the hydrogenated block copolymer. 100 parts by weight of a hydrogenated block copolymer having a content of 20 to 40% by weight, and (b) 100 to 200 parts by weight of a softener for a non-aromatic rubber having a kinematic viscosity at 40 ° C. of 300 mm ² s ⁻¹ or more. And (c) a thermoplastic elastomer composition comprising 10 to 50 parts by weight of a modified polyolefin resin, the hardness of which is in accordance with JIS K6253. 50 ° or less in Rometa, JIS
70 under 25% compression measured according to K6262.
A resin composition having a compression set of 50% or less after left at 22 ° C. for 22 hours. 2. The modified polyolefin resin (c) has a wave number of 1500 to 2000 cm in an infrared absorption spectrum thereof.
^2. The resin composition according to claim 1, which is a polyolefin resin having a functional group having an absorption band at ^-1 . 3. The resin composition according to claim 2, wherein (c) the modified polyolefin resin is a resin obtained by modifying a polyolefin resin containing polypropylene as a main component with an unsaturated carboxylic acid. 4. The resin composition according to claim 3, wherein the unsaturated carboxylic acids are maleic anhydride. 5. A gasket material comprising the resin composition according to claim 1. 6. A metal-integrated gasket formed by using the gasket material according to claim 5. Description: 7. A gasket for a hard disk, comprising the metal-integrated gasket according to claim 6.