JPH056066B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention relates to gaskets used in engines;
In particular, the present invention relates to an asbestos-free gasket having a hooked metal plate suitable as a cylinder head gasket. BACKGROUND ART Compositions containing large amounts of asbestos have traditionally been used to manufacture gaskets, such as cylinder head gaskets, which prevent leakage of high-pressure gas while being subjected to high heat. Asbestos is heat resistant,
Although asbestos has extremely excellent characteristics as a gasket in terms of flexibility and strength, in recent years it has been pointed out that asbestos is harmful to the human body, and the development of asbestos-free gaskets is urgently needed. It's summery. Problems that need to be solved Conventionally used asbestos-based compositions have good entanglement properties due to asbestos's fine structure and good compatibility with inorganic fillers and rubber. It had excellent processability and mechanical properties and sealing properties in the vulcanized sheet state. On the other hand, fibers other than asbestos generally have poor fiber entanglement, and do not have as good compatibility with the above materials as asbestos, so they have poor processability.
There is a problem that the mechanical properties and sealing properties in the vulcanized sheet state are somewhat poor. Therefore, the problem to be solved by the present invention is to develop an asbestos-free gasket using fibers other than asbestos, which is comparable to the asbestos-based gaskets used in the past. Means for Solving the Problems That is, the present invention provides a gasket with a grommet, which has a vulcanized rubber layer containing a non-asbestos fiber material and a filler on both sides of a metal plate with a hook. The compression ratio of the grommet is 15% or less, and the thickness of the grommet is 0.10 of the gasket thickness.
The radius of curvature of the curved portion of the grommet is at least 0.3 times the thickness of the grommet.
This is a gasket with a grommet that is 1.5 times larger. Effects of the Invention In the present invention, the following three constituent requirements are essential, and these requirements act synergistically with each other to provide a gasket with excellent stress relaxation properties, sealing properties, etc. (1) The vulcanized rubber layer containing non-asbestos fiber material and filler must be hard and have a compressibility of 15% or less; (2) The thickness of the grommet must be equal to the thickness of the gasket. 0.10
(3) The radius of curvature of the curved portion in the grommet is at least 1.5 times the thickness of the grommet. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a sectional view of a part of an example of a gasket with a grommet according to the present invention, in which 1 is a metal plate with a hook, 2 and 2' are vulcanized rubber layers, and 3 is a grommet. where Ts is the thickness of the gasket (distance between the surfaces of the vulcanized rubber layers 2 and 2'), Tg is the thickness of the grommet, and R is the radius of curvature of the curved portion of the grommet 3. Gasket thickness Ts is 0.5
Approximately 2 mm or so is appropriate. The metal plate 1 with hooks may be made of iron or other metals with hooks protruding from both sides, which have been conventionally used. The vulcanized rubber layers 2 and 2' are formed of vulcanized rubber containing a filler and a non-asbestos fiber material made of inorganic fibers and/or organic fibers excluding asbestos. Examples of the types of inorganic fibers include ceramic fibers such as alumina-silicate fibers, alumina fibers, zirconia fibers, rock wool, and sepiolite fibers, glass fibers such as quartz glass fibers and high silicate glass fibers, carbon fibers, phosphate fibers, and metals. Commercially available products include non-shot mineral fiber manufactured by Nippon Cement Co., Ltd., ``Lock Fiber'' manufactured by Nittobo Kenzai Co., Ltd., ``Kao Wool'' manufactured by Isolite Kogyo Co., Ltd., ``Fiber Flux'' manufactured by Toshiba Ceramics Co., Ltd., and Unitika U-M Glass. ``Chopped Strand'' manufactured by Asahi Fiberglass, ``Glaslon'' manufactured by Nippon Carbon, ``Carboron Z Yarn'' manufactured by Nippon Carbon, ``Kureha Carbon Fiber'' manufactured by Kureha Chemical Co., Ltd., ``Naslon'' manufactured by Nippon Seisen, Suzuki These include "Suzlon" manufactured by Kinzoku Co., Ltd. and potassium titanate fiber manufactured by Otsuka Chemical Co., Ltd. One or more types of these inorganic fibers can be used. Examples of the types of organic fibers mentioned above include aromatic polyamide fibers, phenolic resin fibers, aromatic polyester fibers, aromatic polyimide fibers, aromatic polybenzimidazole fibers, and cellulose fibers. ``Kynor'' manufactured by Dupont, ``Kepler 29-Valve'' manufactured by Enka, ``Twaron'' manufactured by Enka, ``Vectran'' manufactured by Kuraray.
etc. One or more types of these organic fibers can be used. Examples of filler types include clay, talc,
Heavy calcium carbonate, light calcium carbonate,
These include silica, mica, barium sulfate, carbon black, alumina, vermiculite, etc., and one or more of these can be used. Rubber acts as a binder for fiber materials, and may include natural rubber, styrene-butadiene-copolymer rubber, acrylonitrile-butadiene-copolymer rubber, acrylic rubber, silicone rubber, fluorine rubber, or other synthetic or natural rubber. One or more types of latex and solid rubber can be used. Regardless of whether only inorganic fibers or inorganic fibers and organic fibers are used as non-asbestos fiber materials, the amount of non-asbestos fiber materials used (if inorganic fibers and organic fibers are used, the total amount) is:
Appropriate amounts of the rubber in the vulcanized rubber layers 2 and 2' are approximately 5 to 50% by weight, approximately 5 to 20% by weight for the rubber, and approximately 20 to 80% by weight for the filler. Although only the above-mentioned inorganic fibers may be used as non-asbestos fiber materials,
The combined use of organic fibers has the effect of improving processability during sheet production. On the other hand, if an excessive amount of organic fiber is used, it will have a negative effect on the thermal setting properties of the gasket. Therefore, when organic fibers are used in combination, the amount used is 1 to 200 parts by weight per 100 parts by weight of inorganic fibers.
In particular, it is preferably 10 to 100 parts by weight. In the present invention, it is essential that both the vulcanized rubber layers 2 and 2' have a compression ratio of 15% or less, but layers having such a compression ratio are made of the above-mentioned materials and conventional compositions of this type. A composition containing other compounding agents that are usually added to the product, such as a vulcanizing agent, a vulcanizing aid, an antioxidant, a coupling agent, a coloring agent, etc., is used, and it is pre-formed into a sheet on a roll. Then, the sheet layer is directly pressed onto the hook surface of the hook-equipped metal plate 1, or the composition mass is rubbed directly onto the hook surface using a calender roll, etc., so that the amount of remaining air bubbles is as small as possible. It can be formed by forming a layer on the resin and then heating and vulcanizing it by a conventional method. As described above, in the present invention, (1) the compression ratio of the vulcanized rubber layers 2 and 2' is 15% or less, and (2) the thickness Tg of the grommet 3 is equal to the thickness Ts of the gasket.
0.10 to 0.3 times, and (3) grommet 3
The radius of curvature R of the curved part in is the thickness of the grommet.
It is essential that it is at least 1.5 times Tg.
When the compressibility of each of the vulcanized rubber layers 2 and 2' is greater than 15%, Tg is less than 0.10 times or greater than 0.3 times Ts, and R is less than 1.5 times Ts, the sealing performance of the gasket (conditions (There are cases of surface leakage and interlayer leakage), and grommet 3
There is a problem that it tends to break during use. Therefore, in the present invention, (1) the compression ratio of the vulcanized rubber layers 2 and 2' is 10% or less, and (2) the thickness of the grommet 3 is
Tg is 0.15 to 0.25 times the gasket thickness Ts, and (3) the radius of curvature R of the curved portion of the grommet 3 is at least the grommet thickness Tg.
Preferably it is 1.5 times. Examples Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Examples 1 to 3, Comparative Examples 1 to 2 The following compositions A and B (composition ratio is weight %)
These are kneaded in a kneading machine to make a uniform composition, and then each composition is rubbed on each side of an iron plate with hooks on both sides using a calendar roll, and finally vulcanized at 150℃. A steel vest-type gasket sheet was manufactured using this method. Then, they were cut and punched into a predetermined shape, and finally, grommets were applied at predetermined locations to obtain cylinder head gaskets of Examples 1 to 3 and Comparative Examples 1 and 2. [Composition A] Glass wool (Note 1) 15% Aromatic polyamide fiber (Note 2) 10% Acrylonitrile butadiene rubber 10% Talc 20% Clay 40% Vulcanizing agent 0.5% Vulcanization accelerator 0.5% Pigment 4% Note 1 : "Glasron" manufactured by Asahi Fiber Glass Co., Ltd. Note 2: "Kepler 29" manufactured by DuPont Co., Ltd. [Composition B] Rock wool (Note 1) 10% Alumina-silicate fiber (Note 2) 5% Phenol resin fiber (Note 3) 8% Acrylic rubber 10% Talc 21% Clay 41% Vulcanizing agent 0.5% Vulcanization accelerator 0.5% Pigment 4% Note 1: “CMF” manufactured by Nippon Cement Co., Ltd. Note 2: “Kao Wool” manufactured by Isolite Kogyo Co., Ltd. Note 3: Gunei Chemical "Kynol" manufactured by Kogyo Co., Ltd. Table 1 lists the types of compositions used to form the vulcanized rubber layers of the cylinder head gaskets of Examples 1 to 3 and Comparative Examples 1 to 2, the compression ratio of the vulcanized rubber layers, The graph shows the gasket thickness Ts, the grommet thickness Tg, the radius of curvature R of the curved portion of the grommet, the sealing performance in engine tests, and the presence or absence of cracks in the grommet. The compression ratio and engine test were evaluated using the following methods. Compression ratio: ASTM F36, method A Engine test: 400 cycles of 20℃ x 5 minutes and 120℃ x 5 minutes are repeated for 400 cycles.
During this time, check the sealing performance and check for grommet cracks after the test.

[Table] Effects of the invention The gasket with grommet of the present invention has excellent sealing properties while being asbestos-free.
It also has excellent performance in preventing grommet cracking. Therefore, it is suitable for cylinder head gaskets.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a portion of an example of a gasket with a grommet according to the present invention. 1... Metal plate with hook, 2... Vulcanized rubber layer,
2'... Vulcanized rubber layer, 3... Grommet, Ts...
Gasket thickness, Tg...Grommet thickness,
R...The radius of curvature of the curved portion of the grommet 3.

Claims (1)

[Claims] 1. A gasket with a grommet, which has a vulcanized rubber layer containing a non-asbestos fiber material and a filler on both sides of a metal plate with a hook, wherein the compression ratio of the vulcanized rubber layer is 15% or less, and the grommet A gasket with a grommet, characterized in that the thickness of the grommet is 0.10 to 0.3 times the thickness of the gasket, and the radius of curvature of the curved portion of the grommet is at least 1.5 times the thickness of the grommet.