JPS6317982A - Gasket - Google Patents

Abstract

PURPOSE:A gasket, obtained by providing a sealing layer consisting of an ultraviolet curing polyurethane acrylate, etc., on the surface of a body layer consisting of acrylonitrile-butadiene rubber and heat-resistant fibers and having improved water as well as oil resistance for a long period. CONSTITUTION:A gasket, obtained by partially or wholly coating the surface of a body layer, preferably prepared by blending 100pts.wt. acrylonitrile- butadiene rubber with 75-300pts.wt. heat-resistant fibers, consisting of acrylonitrile-butadiene rubber, preferably with 18-50wt% acrylonitrile content and heat-resistant fibers, preferably aromatic polyamide fibers and/or phenolic resin fibers having 1-20mum outside diameter and 1-50mm length with one or more of an uncured ultraviolet curing polyurethane acrylate and ultraviolet curing polysilicone and carrying out curing and having a sealing layer closely adhering to the surface of the body layer. USE:Suitable for cylinder heads in internal combustion engines, e.g. automotive engines, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a gasket suitable for use as a gasket for automobile engines or other general industrial use, particularly for use in a cylinder hand in an internal combustion engine such as an automobile engine.

Conventional technology and problems to be solved Cylinder head gaskets for internal combustion engines such as automobile engines are used in contact with water and oil at high temperatures and pressures, so they are difficult to solve. As a composition for gaskets, it has stress relaxation properties over a long period of time under high temperature and high pressure.
Although excellent performance is required in various respects such as water resistance and oil resistance, conventionally used cylinder head gaskets cannot necessarily be said to have sufficient performance to meet the above requirements.

Means for Solving the Problems In view of the above circumstances, the present inventors conducted extensive research and as a result, developed the present invention.

In the present invention, the gasket body layer is composed of a composition consisting of acrylonitrile-butadiene rubber and heat-resistant fibers, and a portion of the surface of the body layer or the entire surface thereof is in close contact with the surface of the body layer. The present invention provides a gasket characterized by having at least one sealing layer selected from the group consisting of ultraviolet curable polyurethane acrylate and ultraviolet curable polysilicone.

The sealing layer made of UV-cured polyurethane acrylate and/or UV-cured polysilicone has excellent water resistance and oil resistance, and moreover, the gasket body layer is composed of a composition containing acrylonitrile-butadiene rubber. If the above-mentioned seal layer is formed by applying an ultraviolet curable paint and curing it with ultraviolet rays, a strong bond is formed between the seal layer and the acrylonitrile-butadiene rubber in the main body layer, resulting in problems such as water resistance and oil resistance. An excellent gasket can be obtained.

The main body layer in the present invention is basically composed of a composition consisting of acrylonitrile-butadiene rubber and heat-resistant fibers described later, but fillers, coupling agents, vulcanizing agents, vulcanizing Auxiliary agents, anti-aging agents, pigments, or other rubber chemicals may be added.

As the acrylonitrile-butadiene rubber, those conventionally used in the production of gaskets may be used, but in particular those with an acrylonitrile content of 18 to 50% by weight (commercially available products include Nisopol LX513 manufactured by Nippon Zeon Co., Ltd.).
, Verbunan 3810 manufactured by Bayer, etc.) are preferred.

Examples of heat-resistant fibers include heat-resistant organic fibers, such as aromatic polyamide fibers (commercially available products include Dupon's Kevlar, Enko's Trilon, etc.), phenolic resin fibers (commercially available products include Kynor, available from Koshigaku Kagaku Co., Ltd.), etc. , heat-resistant inorganic fibers such as asbestos, ceramic fibers,
Examples include metal fibers, carbon fibers and other fibers. The ceramic fibers mentioned above include fibers made of natural or artificial nonmetallic inorganic solid materials, such as rock wool, alumina silicate fibers, fused silica, silica glass fibers such as high silicate glass, alumina fibers, and zirconia fibers. Illustrated. Examples of the metal fiber include fibers of heat-resistant metals such as iron, copper, and stainless steel. The heat-resistant fibers used in the present invention may be surface-treated with various resins or a camping agent to be described later.

Among the various heat-resistant fibers mentioned above, heat-resistant organic fibers, particularly aromatic polyamide fibers and phenolic resin fibers, are preferred.

Apart from naturally occurring fibers such as asbestos, among the man-made heat-resistant fibers used in the present invention, preferred are:
The outer diameter is 50 μm or less, especially 1 to 20 pm, and the length is 0.
5 to 200 m, especially 1 to 50 mm.

As the coupling agent, a silane coupling agent, a titanium coupling agent, or other camping agent is used.

The silane coupling agent is preferably T-aminopropyltriethoxysilane (for example, KBE903 manufactured by Shin-Etsu Chemical Co.), γ-mercaptopropyltrimethoxysilane (for example, KBM803 manufactured by Shin-Etsu Chemical Co., Ltd.), N-
Examples include β(aminoethyl)-T-aminopropylmethyldimethoxysilane (for example, KBM603 manufactured by Shin-Etsu Chemical Co., Ltd.).

The titanium coupling agent is preferably isopropyltriisostearoyl titanate (eg, TTS manufactured by Ajinomoto Co.).

Among various coupling agents, silane coupling agents are preferred, and among these, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, etc. are particularly preferred.

Examples of fillers include talc, clay, barium sulfate, silica, mica, carbon, and others.
Those commonly used for gasket compositions are used. The filler may have its surface previously treated with the coupling agent described above.

The amount of heat-resistant fiber used is per 100 parts by weight of acrylonitrile-butadiene rubber (hereinafter, when using the rubber latex as the rubber, it is per 100 parts by weight of solid content contained in the latex), 5
It is used in an amount of 0 to 500 parts by weight, preferably 75 to 300 parts by weight. The amount of filler used is usually 30 parts by weight per 100 parts by weight of axolonitrile-butadiene rubber, except in cases where asbestos and other fillers are hardly used together.
It is used in an amount of 0 to 1000 parts by weight, preferably 500 to 800 parts by weight. The amount of the coupling agent used is 0.5 to 100 parts by weight, preferably 5 to 50 parts by weight per 100 parts by weight of rubber. The amount of rubber chemicals used may be the same as usual, but it is preferable that the total amount of the above-mentioned rubber chemicals used is 3 to 20 parts by weight, particularly 5 to 10 parts by weight, per 100 parts by weight of acrylonitrile-butadiene rubber. .

In the present invention, the sealing layer provided on the gasket body layer is made of at least one member selected from the group consisting of ultraviolet-cured polyurethane acrylate and ultraviolet-cured polysilicone. The sealing layer can be formed by the method described below using an uncured ultraviolet curable paint containing as a main component uncured polyurethane acrylate and/or uncured polysilicone.

Examples of the uncured polyurethane acrylate include polyether polyol-based polyurethane acrylate, polyester polyol-based polyurethane acrylate, and polyurethane acrylate having an ether group and an ester group in the molecule. Examples of the above polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexanediol, neopentyl glycol, cyclohexane dimetatool, Examples include 2,2-bis(4-hydroxycyclohexyl)propane, and bisphenol A to which ethylene oxide or propylene oxide is added. Examples of polyester polyols include reaction products of one or more of the above-mentioned polyether polyols and dibasic acids such as adipic acid, sebacic acid, azelaic acid, and dodecanedicarboxylic acid, or their acid anhydrides. It will be done.

Diisocyanates used when producing polyurethane acrylate using the above materials include aromatic diisocyanates such as tolylene diisocyanate, 4.4'-diphenylmethane diisocyanate, isoporone diisocyanate, and fatty acids such as 4.4'-dicyclohexylmethane diisocyanate. cyclic diisocyanate,
Examples include aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2'-trimethylhexamethylene diisocyanate. In addition, examples of hydroxy group-containing polymerizable monomers include β-hydroxyethyl methacrylate, β-hydroxypropyl methacrylate, and β-hydroxypropyl methacrylate.
-Hydroxy group-containing methacrylates such as -hydroxylauryl methacrylate ε-caprolactone-β-hydroxyethyl methacrylate, and the like.

Examples of the uncured polysilicone include those obtained by reacting a polysiloxane having a hydroxyl group with an alkoxysilane having a methacrylic group, those obtained by reacting a polysiloxane having a hydroxyl group with a compound such as allyl methacrylate, and monocinnamoyloxysilane. Compounds using methyljethoxysilane, compounds in which a bisazide compound is added to polydiorganosiloxane, photosensitive silicones reacted with acryloyl chloride or p-azidohensiate, silicones introduced with mercapto groups, etc. These include silicones with photoinitiators and sensitizers added to silicones into which functional groups have been introduced.

The ultraviolet curable paint used in the present invention may optionally contain various photopolymerization initiators, such as acetophenone, hensifenone, Michler's ketone, benzyl, henzine, henzine ether, hensyl dimethyl ketal, photopolymerizable monomers, such as methyl methacrylate,
Monofunctional monomers such as ethyl methacrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 1
, 3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate,
Difunctional monomers such as neopentyl glycol diacrylate, polyethylene glycol-400 diacrylate, hydroxypipalic acid ester neopentyl glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, poly It may also contain normal amounts of trifunctional to polyfunctional monomers such as methylolpropane polyacrylate. Furthermore, appropriate amounts of sensitizers, stabilizers, etc. may be mixed as necessary.

As a commercially available UV-curable polyurethane acrylate paint, for example, ZF-418-1' manufactured by Nippon Zeon Co., Ltd.
Examples include BYX-8017 manufactured by Asahi Denka Co., Ltd., and XNR-5470 manufactured by Nagase Blastinok Co., Ltd.

As a commercially available UV-curable polysiloxane acrylate paint, for example, X-62-7397 manufactured by Shin-Etsu Chemical Co., Ltd.
, TUV-6000 manufactured by Toshiba Silicon Corporation.

The gasket of the present invention can be applied from a gasket raw material sheet made only of the above gasket body layer constituent materials, or a gasket raw material sheet made by rubbing the above gasket body layer constituent materials on both sides of a core material such as an iron plate with hooks. A gasket is punched out to match the target engine structure, and then the above-mentioned ultraviolet curable paint is screen-coated, roll-coated, curtain-coated, or It can be easily manufactured by applying with a dispenser or the like and curing with ultraviolet rays using a conventional method.

Figures 1 to 3 are partial cross-sectional views of embodiments of the present invention.

In Figures 1 to 3, 1 is the gasket body layer, 2 is the gasket body layer;
3 is a core material made of an iron plate with hooks, and 3 is a sealing layer made of the resin cured by ultraviolet rays. In the embodiment shown in FIG. 1, sealing layers 3 of varying thickness are provided on both sides of the gasket main body layer 1 without a core material, and in the embodiment shown in FIG. Except for perforated parts 4 such as water holes (a sealing layer 3 of a similar thickness is provided on both sides,
In the embodiment of FIG. 3, the gasket body layer 1 has a core material 2.
A sealing layer 3 is provided only around one side of a perforated portion 4 such as a water hole.

Example 1 Acrylonitrile-butadiene rubber with an acrylonitrile content of about 28% by weight (Ninopol L manufactured by Nippon Zeon Co., Ltd.)
X513) 100 parts by weight, asbestos 700 parts by weight, filler talc (Nippon Talc Co., Ltd.'s Talc 5W) 100 parts by weight, vulcanizing agent (Hosoka Kagaku Co., Ltd.'s sulfur) 5 parts by weight, vulcanization accelerator (Iriuchi Shinko) A composition consisting of 5 parts by weight of Tsukusela TT manufactured by Kagaku Kogyo Co., Ltd.
) on both sides, then heated and vulcanized to a thickness of 1.20 mm.
A gasket raw material sheet of m was obtained. Next, a donut-shaped sample with an outer diameter of 75 mm and an inner diameter of 55 mm was punched out from the sheet, and one side of the sample was coated with ultraviolet curable polyurethane acrylate paint (ZF418-11 manufactured by Nippon Zeon Co., Ltd.) in the center.
was coated by a screen coating method and immediately cured by irradiating with ultraviolet rays for about 30 seconds to form a sealing layer with a width of 2 fi and a height of 0.1 fl to obtain a gasket.

Example 2 Verbunan 3810 manufactured by Byer (acrylonitrile content: about 38% by weight) was used as the acrylonitrile-butadiene rubber, and XNR-5 manufactured by Nagase Plastics Co., Ltd. was used as the ultraviolet curable polyurethane acrylate paint.
A gasket having the same structure was obtained in the same manner as in Example 1 except that 470 was used.

Example 3 Acrylonitrile-butadiene rubber with an acrylonitrile content of about 28% by weight (Nisopol L manufactured by Nippon Zeon Co., Ltd.)
X513) 100 parts by weight, aromatic polyamide fiber (Du
40 parts by weight of Kevlar 29 (manufactured by Pont's), 200 parts by weight of rock wool (MF, manufactured by Nippon Cement Co., Ltd.), 300 parts by weight of filler talc (Talc 5W, manufactured by Nippon Talc Co., Ltd.), soft clay (manufactured by Asada Seifun Co., Ltd.) Neocarrier K)3
50 parts by weight, 5 parts by weight of vulcanizing agent (sulfur manufactured by Hosoka Kagaku Co., Ltd.), vulcanization accelerator (Tsukusela TT manufactured by Iruchishikagaku Kogyo Co., Ltd.)
) A gasket having the same structure was obtained in the same manner as in Example 1 except that a composition consisting of 5 parts by weight was used.

Example 4 Ultraviolet curable polysilicone (
A gasket having the same structure was obtained in the same manner as in Example 3, except that X-62-7397 (manufactured by Shin-Etsu Chemical Co., Ltd.) was used.

Example 5 Ultraviolet curable polysilicone (
A gasket having the same structure was obtained in the same manner as in Example 3 except that YUV-6000 manufactured by Toshiba Silicon Corporation was used.

Example 6 A gasket having the same structure was obtained in the same manner as in Example 1, except that an ultraviolet curable polyurethane acrylate paint (BYX-8017 manufactured by Asahi Denka Co., Ltd.) was used as the ultraviolet curable paint.

Comparative Example 1 A gasket having the same structure was obtained in the same manner as in Example 1, except that UV-curable polyether acrylate was used as the UV-curable paint.

Comparative Example 2 A gasket having the same structure was obtained in the same manner as in Example 1, except that UV-curable polyepoxy acrylate was used as the UV-curable paint.

The following water leakage test and oil leakage test were performed on each gasket obtained in Examples 1 to 6 and Comparative Examples 1 to 2, and the results are shown in the table below.

Water leak test: Tighten the test gasket from both sides with a pressure of 50 kg/cm2, and increase the internal water pressure from 0.5 kg/cm” to 0.5 kg.
/cm'' steps and maintained for 15 minutes for each increase in water pressure to check the internal water pressure at which water leakage occurs.The presence or absence of water leakage is visually checked.

Oil Leakage Test: A test was conducted that differed from the above water leakage test in that JIS No. 3 oil was used instead of water.

As mentioned above, the gasket of the present invention is excellent in various points such as water resistance and oil resistance over a long period of time. It is extremely useful for cylinder heads.

[Brief explanation of drawings]

1 to 3 are partial cross-sectional views of embodiments of the present invention. In Figures 1 to 3, 1 is the gas chamber/nod body layer;
2 is a core material made of an iron plate with hooks, 3 is a sealing layer made of ultraviolet-cured resin, and 4 is a perforated portion such as a water hole.

Claims (1)

[Claims] 1. The gasket body layer is made of a composition consisting of acrylonitrile-butadiene rubber and heat-resistant fibers, and a portion of the surface of the body layer or the entire surface of the body layer is A gasket characterized by having at least one sealing layer selected from the group consisting of UV-curable polyurethane acrylate and UV-curable polysilicone in close contact with the surface. 2. The gasket according to claim 1, wherein the heat-resistant fibers are aromatic polyamide fibers and/or phenolic resin fibers.