JPH01252512A - Modified graphite material - Google Patents

Abstract

PURPOSE:To extremely improve resistance to anti-freeze, oil resistance and oxidation resistance of graphite material, by treating the graphite material with an organic titanate-based improver. CONSTITUTION:Expanded graphite, a mat-shaped molded article and a sheetlike molded article thereof may be cited as a graphite material. The graphite material is impregnated with an organic titanate compound such as titanium acylate or titanium alcoholate diluted with a solvent such as water or toluene. Impregnation can be carried out by vacuum potting, pressure potting, etch besides natural impregnation wherein the graphite material is impregnated in a solution. Consequently, the prepared impregnated graphite has excellent resistance to antifreeze, oil resistance, oxidation resistence without lowering compressibility and recovery and is extremely effectively usable as a gasket material for internal combustion engine.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a novel modified graphite material, more specifically, a helad gasket between a cylinder block and a cylinder head of an internal combustion engine, or an exhaust manifold and an exhaust pipe. This invention relates to a modified graphite material suitable for use as a sealing gasket for pipe joints.

[Conventional technology]

Conventionally, such head gaskets or sealing gaskets are made of sheet-shaped graphite, which is made by rolling expanded graphite obtained by treating graphite particles having a laminated structure with an acid treatment or the like, and then heating and expanding the graphite particles. material was used. However, the sheet-like graphite material made in this way does not have sufficient antifreeze resistance, oil resistance, and oxidation resistance necessary for gasket materials, and also lacks physical properties such as tensile strength. A quality method has been proposed.

[Problem to be solved by the invention]

For example, a method is known in which expanded graphite is mixed with a synthetic resin such as phenol resin, acrylic resin, or polyimide resin as a binder and compression molded.The molded product obtained by this method has antifreeze resistance, oil resistance, etc. Although this has been improved, there is a tendency that not only properties such as compressibility and recovery rate that are particularly required as a gasket material are impaired, but also flexibility, which is required in terms of fluid sealing properties, is reduced.

On the other hand, it is also known to treat expanded graphite materials with organosilicon compounds to improve their oxidation resistance and tensile strength. Among them, heat treatment at a high temperature of 5.00 to 2000° C. is required, which poses problems in workability and disadvantages in terms of manufacturing cost and equipment cost.

Thus, the present invention solves the problems of conventional graphite materials and makes it possible to manufacture them without impairing properties such as compression ratio and recovery ratio, and without increasing production costs and equipment costs. According to the present inventors, the purpose is to provide a modified graphite material that can significantly improve antifreeze resistance, oil resistance, and oxidation resistance. It has been found that this can be achieved by treatment with an organic titanate modifier.

[Means to solve the problem]

Therefore, the present invention provides a modified graphite material obtained by treating a graphite material with an organic titanate-based modifier.

The present invention will be explained in detail below.

The present invention relates to a modified graphite material obtained by treating a graphite material with an organic titanate modifier as described above. Examples include molded products and sheet-like molded products. Expanded graphite is produced by treating graphite particles with a layered structure with a strong oxidizing agent such as a mixed acid of concentrated sulfuric acid and concentrated nitric acid, a mixture of concentrated sulfuric acid and potassium permanganate, or a mixture of concentrated sulfuric acid and hydrogen peroxide. It is obtained by treating it with a liquid to produce a flaky intercalation compound, washing it with water, rapidly heating it, and expanding it in the C-axis direction of the graphite crystal, and its specific volume is about 200 to 300 cc/ It is g.

A mat-like molded product of expanded graphite is obtained by compressing the expanded graphite obtained as described above using a roll or press to have a bulk density of 0.05 to 0. 5g/cril, thickness 2~20w1;
: It is a molded wafer-like product, and the sheet-like molded product is made by further compression rolling the expanded graphite described above using a roll or press to have a bulk density of 0.5 to 1.5 sr/d and a thickness of 0.05 to 2. It is molded to .0mm.

When used as a gasket material, it is preferable to use a sheet-like molded product as described above. First, expanded graphite or a matte-like molded product thereof is treated with a modifier, and then compressed to form a sheet-like molded product. can also be used as a gasket material. This makes the subsequent impregnation treatment with the modifier easier.

The modifier used in the present invention is an organic titanate compound having a Ti-0-C bond in its basic structure, and phosphorus-containing organic titanate compounds containing phosphorus can also be advantageously used. Suitable organic titanate compounds or phosphorus-containing organic titanate compounds for use in the present invention include titanium acylate, titanium ψ alcoholade, titanium ψ hydroxy φ carboxylate, titanium phosphate, and phosphate-coordinated titanium acylate. I can give it to you. Although these modifiers can be used as they are without a solvent, they are preferably diluted with a solvent such as water, toluene, isopropanonyl, methyl-ethyl ketone, or the like.

The general formula of such organic titanate compounds is shown in Table 1.

a+b-4 in the general formula R, RR-H or C■~, C2o A1 2゛　3 Lukyl group R5 R4, R5 - represents an alkyl group of C5 to C22.

R1-R5 may be the same or different.

Graphite materials such as expanded graphite, mats or expanded graphite molded sheets are treated with such modifiers. This treatment can be carried out by applying or spraying a solution prepared by diluting the modifier with a solvent onto the graphite material, but is usually carried out by impregnating the graphite material with such a solution. The impregnation method may include a natural impregnation method in which the graphite material is impregnated in a solution, a vacuum injection method, a pressure injection method, etc.

The vacuum injection method is an operation in which expanded graphite, matte, or a molded sheet of expanded graphite is immersed in a modifier solution diluted with a solvent in a container that can withstand reduced pressure, the pressure inside the system is reduced, and then the pressure is returned to atmospheric pressure. It is. The temperature should be room temperature, and the system pressure should be 200℃.
Reduce the pressure to about m+sHg.

The pressurized injection method involves injecting expanded graphite into a container that can withstand pressure.
This is an operation in which a mat or expanded graphite molded sheet is immersed in a solution of a modifier diluted in a solvent, the inside of the system is pressurized with dry air, and then the pressure is returned to atmospheric pressure. The temperature may be room temperature, and the pressure may be 5 kg/c-G.

In addition to the natural impregnation method, modifiers can be impregnated using these methods, but methods such as the vacuum injection method or pressure injection method are generally used when the purpose is to impregnate a large amount in a short period of time, or when a natural impregnation method is used. The impregnation method is carried out when the impregnation takes a long time, but in the case of the present invention, the natural impregnation method is also sufficient for impregnation.

The impregnation time and solution concentration are appropriately selected depending on the target amount of impregnation, but impregnation of expanded graphite or matte progresses more rapidly than that of expanded graphite molded sheets, and during this rapid impregnation, it is difficult to remove the impregnation from the solution. This increases the variation in the amount of impregnation. Therefore, when impregnating expanded graphite or mat, it is preferable to lower the solution concentration, lengthen the impregnation time, wait until the amount of impregnation becomes stable, and then pull it up. On the other hand, when impregnating an expanded graphite molded sheet, if the impregnation time is longer than 10 seconds, the sheet will swell and its original thickness or appearance will be damaged, so it is preferable to keep the impregnation time to 10 seconds or less. .

The impregnated or sprayed modifier is cured by moisture, but is usually cured by heating. The heating temperature is determined by considering the boiling point of the alcohol generated after hydrolysis, or the boiling point of the solvent when using a solvent, but is usually 100~
A relatively low temperature range of 150℃, 120-130℃
A range of 0.degree. C. is preferred and heating is performed at this temperature for 1 to 2 hours.

The amount of the modifier adhered to the graphite material by heating and hardening is in the range of 0.01 to 20 parts by weight after hardening, based on 100 parts by weight of the graphite material before impregnation etc. Especially from 0.1
A range of 10 parts by weight is preferred.

If the HHk is less than this, there will be no effect of improving antifreeze resistance, oil resistance, and oxidation resistance, and if it is too much, the flexibility and self-lubricating properties of the graphite material will be impaired, and the sealing performance of the gasket will be reduced. do.

In this way, the modified graphite material can be changed, but as is clear from the data shown in the examples below, this improves antifreeze resistance, oil resistance, and oxidation resistance without reducing compressibility and recovery rate. It has excellent properties such as properties and can be used extremely effectively as a gasket material for internal combustion engines.

〔Example〕

(Example 1) Expanded graphite molded sheet with a thickness of 0.38+lIm and a bulk density of 1.05 g/i (manufactured by Union Carbide, trade name: GRA)
FOIL) was cut into test pieces with a width of 25+ am and a length of 50 mm, and 10 parts by weight of a titanium acylate modifier (manufactured by Nippon Bakuichi Co., Ltd., trade name: Titacoat S-582) and 9 parts of toluene were added.
Immersed in 0 parts by weight solution for 5 seconds, pulled up and heated to 120°C.
Heated for 2 hours.

The amount of the modifier deposited at this time was 1.4 parts by weight based on 100 parts by weight of the expanded graphite molded sheet before treatment.

(Example 2) Using the same expanded graphite sheet as in Example 1, titanium
Alcolade modifier (manufactured by Mitsubishi Gas Chemical, trade name: TST)
) was used, but the same treatment as in Example 1 was carried out. The amount of modifier attached at this time is 100% of the expanded graphite molded sheet before treatment.
The amount was 1.6 parts by weight.

(Example 3) Using the same expanded graphite molded sheet as in Example 1, it was soaked in a solution of 10 parts by weight of a titanium hydroxycarboxylate modifier (manufactured by Mitsubishi Gas Chemical, trade name TLA) and 90 parts by weight of water for 5 seconds. After being immersed and pulled up, it was heated at 120°C for 2 hours. The amount of the modifier deposited at this time was 0.45 parts by weight based on 100 parts by weight of the expanded graphite molded sheet before treatment.

(Example 4) The same expanded graphite molded sheet as in Example 1 was used, and a titanium phosphate modifier containing phosphorus (manufactured by Nippon Kaitatsu,
The same treatment as in Example 1 was performed except that TITACOAT P-151P (trade name) was used.

The amount of modifier attached at this time is 1% of the expanded graphite sheet before treatment.
It was 183 parts by weight relative to 00 parts by weight.

(Example 5) Expandable graphite flakes obtained by acid-treating graphite particles having a laminated structure and washing with water (GTC manufactured by Union Carbide)
The flakes) were heated at 1000°C for 5 to 10 seconds to obtain expanded graphite.

The expanded graphite was immersed for 60 seconds in a solution of 0.3 parts by weight of a titanium acylate modifier (manufactured by Nippon Soda, trade name: Titacoat S-582) and 99.7 parts by weight of toluene. After pulling, it was heated at 120°C for 2 hours, and then rolled to a thickness of 0.38 mm.

An expanded graphite molded sheet having a bulk density of 1.05 r/cd was obtained.

The amount of modifier attached at this time is 100f of expanded graphite before treatment.
[The amount was 1.4 parts by weight based on the total weight.

(Example 6) Expanded graphite obtained by heating graphite flakes as in Example 5 was rolled with a roll to obtain a material with a thickness of 4.5 fins and a density of 0.
A wafer-like mat was obtained. The mat was immersed for 60 seconds in a solution of 0.4 parts by weight of a titanium e-phosphate modifier (manufactured by Nippon Soda, trade name: Titacoat P-151P) and 99.6 fflffi parts of toluene, and after being pulled up, it was heated at 120° C. for 2 hours. . Thereafter, an expanded graphite molded sheet having a thickness of 0.38 mm and a bulk density of 1.05 g/cal was obtained by rolling. At this time, the adhesion amount of the modifier is 1.0 parts by weight per 100 parts by weight of the mat before treatment. (Comparative Example) The same expanded graphite molded sheet provided in Example 1 was used as a comparative sample without any treatment.

Compressibility of expanded graphite molded sheets manufactured in Examples 1 to 6 and Comparative Examples measured according to JIS R-3453,
The results of the recovery rate are shown in Table 2.

Table 3 shows the properties of the graphite sheet.

(Explanation of items in Table 3) *1 Antifreeze resistance: ASTM to check antifreeze resistance
According to F-146, 20 parts by weight of water and antifreeze (Isuzu Automobiles, product name: Long Life Coolant Super) 8
Mass increase rate after immersion and boiling in 0 parts by weight of mixed liquid for 22 hours,
Measurement results of thickness increase rate.

*2 Oil resistance: JISR-345 to check oil resistance
3, the measurement results of the mass increase rate and thickness increase rate after immersion heating in Pk1.3 lubricating oil at 150°C for 5 hours.

*3 Oxidation resistance: Matsufuru Furnace 7 to examine oxidation resistance
Measurement results of heating weight loss rate in a 70°C atmosphere.

In the case of the modified graphite material according to the present invention, it is clear from Table 2 that the compressibility and recovery rate, which are important as gasket materials and backing materials, are not impaired, and antifreeze resistance and
It has excellent oil resistance and oxidation resistance, and the effect of the modifier is remarkable. [Effects of the Invention] As is clear from the above, graphite material is treated with an organic titanate modifier according to the present invention. The modified graphite material obtained by this treatment has various properties such as antifreeze resistance, oil resistance, and oxidation resistance without sacrificing the compressibility and recovery rate necessary for gasket materials, as well as flexibility and pliability. can be improved.

Moreover, in industrial manufacturing, it can be easily manufactured continuously by heating and curing at low temperatures in a short time without using special processing atmospheres or high temperatures, reducing manufacturing costs and equipment costs. It is also good in terms of performance and economy.

Therefore, the reforming material according to the present invention is particularly effective for use as a gasket for sealing between the cylinder block and cylinder head of an internal combustion engine or in a high-temperature section.

Applicant's agent: Mr. Sato

Claims (1)

[Claims] 1. A modified graphite material obtained by treating a graphite material with an organic titanate-based modifier. 2. The modified graphite material according to claim 1, wherein the graphite material is expanded graphite. 3. The modified graphite material according to claim 1, wherein the graphite material is a mat-like molded product made by compressing expanded graphite. 4. The modified graphite material according to claim 1, wherein the graphite material is a sheet-shaped molded product obtained by rolling expanded graphite. 5. The modified graphite material according to claim 1, wherein the organic titanate modifier is a phosphorus-containing organic titanate modifier.