JPH06117544A - Expansion graphite-metal gasket material - Google Patents

Abstract

PURPOSE:To provide a metal gasket material which is excellent in anti-heat durability and workability at high temperature such as laser processing, by bonding an expansion graphite sheet on one side or both sides of a metal thin late by using a bonding agent of heat hardening resin which is mixed with the micropowder of expansion graphite. CONSTITUTION:This expansion graphite-metal gasket material which is most suitably used for an automobile internal combustion engine or the like is manufactured by bonding an expansion graphite sheet on one side or both sides of a metal thin plate by using a bonding agent of heat hardening resin which is mixed with the micropowder of expansion graphite. As for the micropowder of expansion graphite, what is less than 350mum in the average granule diameter is used, and the bonding agent contains 0.1-20wt.% of this. Also, as for the expansion graphite sheet, there is no limit so long as expansion graphite is used as a material, but thickness of about 0.05-0.5mm should be used, and as for the metal thin plate, a stainless steel plate or an iron plate or the like is used generally.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expanded graphite-metal gasket material used for general industries such as automobiles, industrial machines and chemical plants.

[0002]

2. Description of the Related Art Expanded graphite is beginning to be used as a sealing material such as gaskets and packings as a substitute material for asbestos because it has excellent sealing properties, compression restoring properties, stress relaxation properties, chemical resistance and the like. Expanded graphite gasket materials generally used for internal combustion engines of automobiles are disclosed in Japanese Examined Patent Publication No.
As disclosed in JP-A-33799, graphite having a highly developed crystal structure such as natural graphite, quiche graphite, and pyrolytic graphite is prepared from a mixed solution of concentrated sulfuric acid and nitric acid, potassium permanganate, hydrogen peroxide solution, and the like. The graphite intercalation compound is formed by acid treatment with the following oxidizing treatment liquid, washed with water, and rapidly heated to expand in the C-axis direction of the graphite crystal. An inter-processed expanded graphite sheet is used. Since this expanded graphite sheet alone retains its strength by the bonding force only between the expanded graphite particles, it is difficult to use it alone as a gasket for an internal combustion engine. An expansive graphite sheet is fixed on both sides of a metal reinforcing core plate of 0.15 to 0.25 mm by using the above-mentioned projection by roll processing or the like, and a thickness of 1.0 to
Used as 1.6mm gasket material.

[0003]

However, when the gasket material as described above is applied to an internal combustion engine,
Since the surface pressure is concentrated on the circular protrusions of the metal reinforcing core plate used, water leakage or oil leakage may occur around the water hole or the oil hole under severe conditions. Further, when this gasket material is used as a head gasket, a load is applied to the gasket due to thermal deformation of the cylinder head and the cylinder block, and the cylinder bore portion is deformed, so that the rotation efficiency of the cylinder due to combustion of the engine is poor. Eliminating such problems, excellent sealing of water, oil and gas,
As a gasket material having improved cylinder rotation efficiency and low fuel consumption, as shown in JP-A-2-107869, a thin plate in which expanded graphite sheets are attached to both sides of a metal thin plate with a thermosetting resin adhesive. There is a gasket material and it is in the spotlight. However, although such a gasket material has a good sealing property as described above, it has a limit in heat resistance, and when the actual machine is subjected to a heat load, the thermosetting resin swells or peels off. In addition, in many cases, punching dies are not manufactured at the time of trial production before mass production. Therefore, even when high temperature processing such as laser processing is required, swelling or peeling occurs in the resin part and it is not put into practical use. I can't plan.

The present invention solves the above-mentioned drawbacks and is excellent not only in sealing water, oil and gas, but also in heat resistance and durability.
An object of the present invention is to provide an expanded graphite-metal gasket material which is excellent in high temperature processing such as laser processing.

[0005]

DISCLOSURE OF THE INVENTION The present invention uses an adhesive of a thermosetting resin in which fine powder of expanded graphite is mixed, and an expanded graphite sheet obtained by adhering an expanded graphite sheet to one side or both sides of a thin metal plate. Regarding gasket material.

In the present invention, the expanded graphite sheet is not particularly limited as long as it uses expanded graphite as a raw material, but preferably has a thickness of 0.05 to 0.5 mm. If it is too thin, it is difficult to handle, and if it is too thick, water and oil leaks easily occur due to heat load. The material of the thin metal plate is not particularly limited, but a stainless steel plate or an iron plate is generally used. The thickness of the thin metal plate is from the viewpoint of ensuring water resistance and oil resistance when the thickness of the entire gasket is 0.4 to 1.2 mm.
2 to 1.0 mm is preferable. The thermosetting resin used as the adhesive is preferably a varnish such as a phenol resin, an epoxy resin, a furan resin, a melamine resin or a polyimide resin.

The expanded graphite fine powder to be mixed with the thermosetting resin preferably has an average particle diameter of 350 μm or less. If the particle size is large, traces of expanded graphite particles will remain on the gasket surface,
The tightening surface pressure may be uneven and the sealing performance may be reduced. The compounding amount of the fine powder of expanded graphite in the adhesive is 0.
1 to 20% by weight is preferable. If the amount of the expanded graphite fine powder is large, the tightening surface pressure becomes non-uniform and the sealing performance is deteriorated. If the amount is too small, the effect of mixing fine powder cannot be obtained. The fine powder of expanded graphite may be obtained by crushing an expanded graphite sheet to a desired particle size with a fine pulverizer such as a jet mill. It is preferable to use a scrap material generated during the production of the expanded graphite sheet from the viewpoint of resource reuse.

In order to obtain a gasket material, first, a predetermined amount of expanded graphite fine powder is added to and mixed with a varnish of thermosetting resin. Expanded graphite powder has good wetting with varnish,
In particular, uniform mixing can be easily performed without using a kneader or the like. Next, an adhesive is applied on the thin metal plate, an expanded graphite sheet is attached thereto, and the resin in the adhesive is cured to obtain a gasket material.

[0009]

[Function] When a thermosetting resin is used alone as an adhesive and electric discharge machining or laser machining is performed, heat is accumulated and heat is generated at the bonded portion,
Heat deterioration causes resin swelling and peeling. In contrast,
When a mixture of a proper amount of expanded graphite fine powder and a resin is used, the thermal conductivity and electric conductivity of the adhesive are significantly improved, and swelling and peeling are almost eliminated. When applied to the head gasket, the heat generated by the engine due to combustion can be immediately carried out of the system, so that the heat load on the gasket can be reduced and the heat resistance and durability of the gasket can be improved. This is because the expanded graphite particles are scaly and have particularly high thermal conductivity and electrical conductivity in the plane direction, so when blended in an adhesive and applied to a thin metal plate, thermal conductivity and electrical conductivity Oriented in a plane direction with good properties, expanded graphite is easy to crush,
By obtaining the desired fine particles and uniformly dispersing them in the resin.

[0010]

EXAMPLES Examples of the present invention will be described below. Example 1 Phenolic resin (manufactured by Hitachi Chemical Co., Ltd., VP-11N) 90
10 parts by weight of expanded graphite powder having an average particle size of 200 μm obtained by pulverizing the end material of the expanded graphite sheet with a jet mill is mixed with parts by weight, and the mixture is applied to both surfaces of a SUS304 plate having a thickness of 0.3 mm. A 0.2 mm thick expanded graphite sheet (manufactured by Hitachi Chemical Co., Ltd., trade name: CARBOFIT) was pasted onto this, and the resin was cured by pressure bonding at 180 ° C. for 30 minutes with a hot press to obtain an expanded graphite-metal gasket material. Obtained.

Example 2 90 parts by weight of furan resin (manufactured by Hitachi Chemical Co., Ltd., VF-303) was mixed with 10 parts by weight of the expanded graphite powder similar to that of Example 1, and this was mixed into a cold-rolled steel sheet having a thickness of 0.8 mm. (SPCC) is coated on both sides, and the same expanded graphite sheet as in Example 1 is attached onto this, and the resin is cured by pressure bonding at 160 ° C. for 30 minutes by hot pressing to obtain an expanded graphite-metal gasket material. It was

Comparative Example 1 An expanded graphite-metal gasket material was obtained in the same manner as in Example 1 except that an adhesive made of only a phenol resin which was not mixed with the expanded graphite powder in Example 1 was used. Comparative Example 2 An expanded graphite-metal gasket material was obtained in the same manner as in Example 2 except that the adhesive containing only the furan resin containing no expanded graphite powder in Example 2 was used.

The gasket materials obtained in the above-mentioned Examples and Comparative Examples were subjected to electric discharge machining and laser machining to evaluate the high temperature machinability, and the appearance of the cut surface was observed. In addition, as an evaluation of heat resistance, the flange 1 as shown in FIG.
The test piece 3 of the gasket processed into the outer diameter D = 50 mm and the inner diameter d = 34 mm was assembled into the
Tighten with a surface pressure of 00 kg / cm ² , 300 to 5 from the through hole 2.
Hot air at 00 ° C. was blown into the space 4 for 2 hours, and the appearance was observed. To further evaluate the sealing performance, the flange 1 of FIG.
When a test piece 3 having the same shape as that of the heat resistance test is attached to the space, a space 4 in the flange is filled with a 50% by weight aqueous solution of ethylene glycol, and an air pressure of 2 to 7 kg / cm ² is applied from the opening 2 The state of leakage of ethylene glycol was observed. The results of these tests are shown in Table 1. In the table, ◯ indicates no abnormality, Δ indicates blistering, and X indicates peeling.

[0014]

[Table 1]

From Table 1, the gasket materials of Examples 1 and 2 in which a fine powder of expanded graphite was blended in the adhesive were Comparative Example 1
Compared with the gasket materials of No. 2 and No. 2, swelling or peeling of an adhesive portion does not occur during laser processing or electric discharge processing, and high-temperature processability is good. It is also shown that they have excellent heat resistance and sealing properties.

[0015]

According to the present invention, in the expanded graphite-metal gasket material, the high temperature processability such as laser machining and electric discharge machining, which has been a problem in the past, is improved, and the heat resistance is also improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method for testing the sealing performance of a gasket material.

[Explanation of symbols]

1 ... Flange, 2 ... Port, 3 ... Test piece, 4 ... Space, 5
…bolt

Claims (3)

[Claims] 1. An expanded graphite-metal gasket material obtained by adhering an expanded graphite sheet to one or both sides of a thin metal plate using an adhesive of a thermosetting resin mixed with fine powder of expanded graphite. 2. The average particle size of the expanded graphite fine powder is 350 μm.
The expanded graphite-metal gasket material according to claim 1, which has a m or less. 3. An expanded graphite fine powder in an amount of 0.1 to 10 in the adhesive.
The expanded graphite-metal gasket material according to claim 1 or 2, comprising 20% by weight.