JPS63293364A - Water swelling type lubricatable gasket - Google Patents

Abstract

PURPOSE:To obtain a compromise between a mechanical characteristic and a water swelling and lubricating ability by vulcanizing a composition material consisting of 1 to 20 wt% of water swelling type powder like organic polymer having a granular size of less than 50 mum and the remainder of reinforcing fibers and rubber filler so as to obtain a sheet-like material. CONSTITUTION:A composition material containing therein about 3 to 40 wt% of reinforcing fibers such as phenol resin fibers, carbon fibers, ceramic fibers, metallic fibers or the like, about 5 to 30 wt% of rubber such as natural rubber, acrylic rubber or the like, about 50 to 85 wt% of filler such as talc, clay, silica or the like and 1 to 20 wt% of water swelling type powder-like lubricatable organic polymer having a particle size of less than 50 mum is formed into a sheet-like material and is heated and vulcanized so as to produce a gasket having a thickness of less than about 0.3 to 3 mm. Hydrophilic or waterinsoluble natural or synthetic polymer materials containing ionized group materials or the salt thereof, and/or noionzied hydrophilic group materials, is used as the above mentioned water swelling type lubricatable polymer.

Description

[Detailed Description of the Invention] The present invention relates to a gasket used as a sealing material for various industrial machines such as automobiles and production machines, and is particularly suitable for use in areas that require water sealing. Regarding gaskets.

Conventionally, asbestos joint sheets have been widely used as sealing members to prevent leakage at the connections of cooling water piping systems in automobile engines. By the way, due to the recent trend of reducing the weight of automobiles, 1. There is a growing trend to reduce the weight of the entire cooling water piping system by thinning the flanges of the cooling water piping system and reducing the diameter of the bolts used to tighten the flanges. When trying to thin the flange and reduce the diameter of bolts used to tighten the flange, it is necessary to reduce the surface pressure when tightening the sealing member.As a result, conventional asbestos joint sheets, etc. When using flange, water leakage problems often occur at the contact surface with the flange.

In order to solve the above problem, a gasket containing water-swellable organic polymer fibers has been proposed. The organic polymer fibers swell and tend to increase the thickness of the gasket, and this action increases the surface pressure of the gasket, resulting in the effect of improving sealing performance.

By the way, in the above gasket, in order to improve its mechanical properties, it is necessary to mix a certain amount of inorganic or organic fibers with high tensile strength, that is, reinforcing fibers.
If water-swellable organic polymer fibers are added to this, the fibers generally have poor miscibility with rubber, so the dispersibility of the sheet decreases, the composition becomes non-uniform, and the mechanical properties of the sheet deteriorate. There is a problem with a significant decline. If the amount of reinforcing fiber used is reduced in order to improve the dispersibility of the sheet, the mechanical properties of the resulting sheet will be unsatisfactory, and -
If the amount of polymer fiber used is reduced, the water swelling property of the resulting sheet will be unsatisfactory, and the above-mentioned effect of improving sealing performance based on water absorption will be poor.

The present invention aims to solve the problem by providing a water-swellable gasket that has excellent sheet mechanical properties and water-swellability.

That is, the present invention comprises a reinforcing fiber, a rubber, a filler, and a powdery water-swellable organic polymer having a particle size of 50 μm or less, and the content of the powdery water-swellable organic polymer is 1 to 20 μm.
This water-swellable gasket is characterized in that it is formed into a sheet by vulcanizing a composition of % by weight.

Powder-like water-swellable organic polymers generally do not have good miscibility with various rubbers and fibers, so conventionally gaskets containing the powder-like water-swellable organic polymers have a powdery water-swellable property during use. It has been pointed out that there is a problem with organic polymers separating and flying out into the water. However, according to the findings of the present inventors, contrary to expectations, the particle size was 5.
0. The fine powder of UA+ or less has excellent miscibility with various rubbers, and has excellent dispersibility even when combined with the required amount of reinforcing fiber to ensure water sealing properties. A sheet with good properties and therefore good mechanical properties is obtained. It has also been found that the above-mentioned problems of separation and popping out are not a problem from a practical standpoint.

The rubber used in the present invention may include natural rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, or other rubbers conventionally used by Joint Sheet. Preferred are those exemplified above.

As reinforcing fibers, inorganic fibers with high tensile strength, especially non-asbestos inorganic fibers and/or organic fibers,
For example, phenolic resin fiber, aromatic polyamide fiber,
Aromatic polyester fiber, aromatic polyimide fiber, carbon fiber, ceramic fiber, rock wool, alumina fiber,
Glass fibers such as quartz glass, metal fibers, or other materials may be used.

Among these fibers, preferred are those having an outer diameter of 50 μm or less, especially 1 to 20 μm, and a length of 0.5 to 20 μm, especially 1 to 10 m.

By using organic or inorganic fibers other than asbestos, an asbestos-free gasket with better processability can be obtained from the present invention.

Fillers include various agents commonly used in gaskets, such as talc, clay, barium sulfate, silica,
etc. are used. In general, the finer particles of the filler are preferred, and those with a particle size of 100 mesh or more, particularly 250 mesh or more are particularly preferred.

As the water-swellable organic polymer, a substance that is insoluble in water but swells with water is used. Substances with such properties include carboxyl groups, sulfone groups, phosphoric acid groups,
Ionizable groups such as quaternary ammonium bases, amino groups, imino groups, pyridium bases or their salts and/or nonionic hydrophilic groups such as hydroxyl groups, ether groups, chain or cyclic amide groups, and nitrile groups. Containing natural or synthetic hydrophilic and water-insoluble polymeric substances are used. For example, copolymers of acrylic acid or its salts and divinylbenzene, alkali hydrolysates of acrylo, copolymers of nitrile with vinyl chloride and ethylene monomers, and copolymers of acrylonitrile with vinylidene chloride and ethylene monomers. Alkaline hydrolysates of copolymers, formaldehyde crosslinked acrylamide polymers, acid condensates of polyacrylic acid and polyvinyl alcohol, epichlorohydrin crosslinked polyvinyl alcohols, and polymers produced by hydrolyzing acrylonitrile polymers with alkali. formaldehyde crosslinked product, phosphoric acid condensate of polyvinyl alcohol, copolymer of 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate, copolymer of 2-methyl-5-vinylpyridine and N-N'-methylenebisacrylamide. Polymer, copolymer of N-N'-dimethylaminoethyl methacrylate and N-N'-methylenebisacrylamide, copolymer of N-vinyl-2-pyrrolidone and ethylene glycol dimethacrylate, radiation of polyoxyethylene Crosslinked product by irradiation, acidic heating condensate of starch, saponified product of starch-acrylonitrile graft copolymer, dried product of saponified copolymer of vinyl ester and ester unsaturated carboxylic acid or its derivative, isobutylene-malein These include acid copolymers.

The water-swellable organic polymer used in the present invention needs to be in the form of a fine powder with a particle size of 50 μm or less for the reasons described above. If a particle size larger than 50 μm is used, it will be difficult to mix with rubber and fibers. is relatively poor, and gaskets containing it have a greater tendency to separate and pop into the water during use. Therefore, the water-swellable organic polymer preferably has a particle size of 40 μm or less, particularly 30 μm or less in the form of a fine powder.

In addition to the above-mentioned components, the composition of the present invention includes rubber chemicals that are usually added to compositions for joint sheets, such as vulcanizing agents, vulcanization accelerators, anti-aging agents, pigments, plasticizers, and stabilizers. , a coupling agent, a flame retardant, or other chemicals, if necessary.

Next, the usage amount of each compounded component will be described.

The reinforcing fibers are used in an amount of about 3 to 40% by weight, preferably about 7 to 25% by weight. If it is less than 3% by weight,
The mechanical properties of the gasket are not sufficient, and if the amount is more than 40% by weight, the processability into sheets will be poor.

The rubber is used in an amount of about 5 to 30% by weight, preferably about 5 to 20% by weight. If it is less than 5% by weight, the mechanical properties and sealing properties of the gasket will be insufficient, resulting in
If it exceeds % by weight, the stress relaxation properties of the gasket will deteriorate.

The filler is about 50 to 85% by weight, preferably 55 to 75% by weight.
It is used in a range of about % by weight. If it is less than 50% by weight, the stress relaxation properties of the gasket will not be sufficient, and if it is less than 85% by weight.
If the amount is higher, the mechanical properties of the gasket will deteriorate.

The powdered water-swellable organic polymer is used in an amount of 1 to 20% by weight. If it is less than 1 part by weight, the effect of increasing surface pressure due to water swelling of the gasket will be poor, whereas if it is more than 20 parts by weight, not only will the degree of water swelling of the gasket become saturated, but also the stress relaxation properties of the gasket will deteriorate. Kaya - It gets worse. Therefore, the powdered water-swellable organic polymer is preferably used in an amount of 3 to 15% by weight, particularly 5 to 10% by weight.

The gasket of the present invention is produced by uniformly mixing the above-mentioned materials in a predetermined ratio using a conventional kneading machine, such as a Loedige mixer or an Eirich mixer, to prepare a composition consisting of these components. It can be produced by forming it into a sheet using a calendar roll and then heating and vulcanizing it.

The thickness after vulcanization, that is, the thickness of the gasket of the present invention is 0.
．． About 3 to 3 cranes, especially about 0.5 to 2 dragons, are often used.

As mentioned above, the composition constituting the gasket of the present invention has excellent miscibility due to the use of a water-swellable organic polymer in the form of a fine powder with a particle size of 50 μm or less, and it can be water-sealed. Even if the required amount is used in combination with the necessary amount of reinforcing fibers, a sheet with good dispersibility and therefore good mechanical properties can be obtained. Further, the water-swellable organic polymer in the form of fine powder exhibits good water-swellability, and there is virtually no problem of separation or popping out of the water-swellable organic polymer during use of the gasket of the present invention. Therefore, the gasket of the present invention has an excellent effect of exhibiting stable and high sealing performance over a long period of time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Below, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 Phenol resin fiber (trade name Kynol manufactured by Gunei Kagaku Co., Ltd.) 15% by weight, styrene-butadiene rubber (trade name JSRO561 manufactured by Japan Synthetic Rubber Co., Ltd.) 12% by weight (solid content equivalent), talc 66% by weight, A composition consisting of 5% by weight of a finely powdered water-swellable organic polymer (trade name Sumikagel 5P-520, manufactured by Sumitomo Chemical Co., Ltd., average particle size: 20 μm) and 2% by weight of rubber chemical 1 (including pigment). The mixture was prepared by kneading for about 1 hour in a kneader equipped with a cooling means. This composition was supplied between a hot roll and a cold roll of a calender roll, and the composition was laminated on the surface of the hot roll to form a sheet with a thickness of 1.0 mm, and then heated at 150°C for 30 minutes. Heat and vulcanize 1
．． I got a gasket with a thickness of 0.

Example 2 As a fine powder water-swellable organic polymer, Sumikagel NP-1020 (trade name) manufactured by Sumitomo Chemical Co., Ltd. (average particle size: 20 μm)
1. was carried out in the same manner and under the same conditions as in Example 1 except that 1.
A gasket of Ofi thickness was obtained.

Example 3 A gasket with a thickness of 1.0 m was obtained in the same manner and under the same conditions as in Example 1, except that acrylonitrile-butadiene rubber (trade name Kynor LX-513, manufactured by Nippon Zeon Co., Ltd.) was used instead of styrene-butadiene rubber. .

Example 4 1. was carried out in the same manner and under the same conditions as in Example 1, except that acrylic rubber (trade name Kynor LX-812, manufactured by Nippon Zeon Co., Ltd.) was used instead of styrene-butadiene rubber. Own
I got a thick gasket.

Example 5 Aromatic polyamide fiber (
A gasket with a thickness of 1.On was obtained in the same manner and under the same conditions as in Example 1, except that a gasket (trade name: Kepler, manufactured by DuPont) was used.

Comparative Example 1 Same as Example 1 except that Sumikagel N-100 (trade name, manufactured by Sumitomo Chemical Co., Ltd.) (average particle size: 20011 m+) was used instead of the fine powder water-swellable organic polymer used in Example 1. A gasket with a thickness of 1.0 mm was obtained using the method and conditions.

Each gasket of Examples 1 to 5 and Comparative Example 1 was evaluated for tensile strength in normal state, water sealing property, ability to pop out water-swellable organic polymer into water, and stress relaxation property using the methods shown below. The results are shown in Table 1.

Tensile strength: Measured in accordance with JIS R3453-1985.

Water sealing property: A donut-shaped sample with an outer diameter of 90 mm and an inner diameter of 74 mm is sandwiched between iron flanges, and the iron flanges are tightened from both sides with a pressure of 30 kir/c+1 to reduce the internal water pressure to 0.
Increases from 5kg/cd in steps of 0.5kg/-,
The water pressure (kg/cd) was measured when water leakage was visually observed between the iron flanges. Note that the holding time at each water pressure was 15 minutes.

Ejectability into water: A short sheet of 2m theory

Excellent: No separation or protrusion of the water-swellable organic polymer from the gasket.

Good: There is slight separation or protrusion of the water-swellable organic polymer from the gasket.

Acceptable: The water-swellable organic polymer has separated or jumped out to a considerable extent from the gasket.

Stress relaxation property: Measured according to the test method of JIS R3453-1985.

Table 1

Claims (1)

[Claims] 1. Reinforcing fiber, rubber, filler, and particle size of 50 μm
A composition comprising the following powdered water-swellable organic polymer and having a content of 1 to 20% by weight of the powdered water-swellable organic polymer is vulcanized to form a sheet. water-swellable gasket. 2. The water-swellable gasket according to claim 1, wherein the rubber is natural rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, or acrylic rubber. 3. Claim 1 or 2, wherein the reinforcing fibers are organic fibers and/or non-asbestos inorganic fibers.
The water-swellable gasket described in Section.