JP2002020729A - Rubber composition for sealing material and sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition which is used for sealing materials and has excellent oil resistance against fluorooil thermal media, excellent low temperature resistance, and excellent adaptability to clean surfaces in processes for producing semiconductors, and especially exhibits excellent suitability, when used for temperature control units, and to provide a sealing material obtained by molding the rubber composition. SOLUTION: This rubber composition for sealing materials, containing as an essential rubber component an ethylene-propylene-based copolymer rubber comprising 30 to 50 wt.% of constituting units originated from propylene, 1 to 15 wt.% of constituting units originated from ethylidene norbornene, the remainder of constituting units originated from ethylene as a rubber component, and silica as a filler. The sealing material obtained by molding the rubber composition for the sealing materials as a material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for a sealing material which exhibits particularly excellent suitability for a heat medium of a fluorine-based oil, and a sealing material obtained by molding this rubber composition.

[0002]

2. Description of the Related Art Generally, a fluorine-containing rubber composition or a fluorosilicone-based rubber is used as a sealing material for a semiconductor process temperature control unit using a fluorine-based oil as a heat medium, such as a semiconductor manufacturing process. Although the composition is used as a molding material, there is a problem in that it is expensive and lacks easy adoption. In addition, even if these compositions are used, swelling of the fluorine-based oil (perfluoropolyether-based oil) still poses a problem. On the other hand, since the ethylene-propylene-based copolymer rubber composition is inexpensive, if its oil resistance is enhanced, it can be applied to a fluorine-based oil.

Various techniques have been proposed to date for improving the oil resistance of ethylene-propylene copolymer rubber compositions. For example, Japanese Patent No. 25776648
No. 2 is based on the technology of blending two types of ethylene-propylene copolymer rubbers with different Mooney viscosities at the specified compounding ratio. Attempts to preserve performance have been disclosed, and furthermore, Patent No. 2889929 discloses unsaturated bonds and / or
Alternatively, by mixing an organopolysiloxane having a mercapto group, an oil-extended ethylene-propylene-based copolymer rubber, and a non-oil-extended ethylene-propylene-based copolymer rubber at a specified component ratio, the mixed composition has oil resistance. Attempts to simultaneously provide various performances, including: However, all of these prior arts take oil resistance to hydrocarbon oils into consideration, and are fluorinated oils (perfluoropolyether oils) used in the present invention.
It does not address the specific oil resistance of

[0004] Fluorine-based oils (perfluoropolyether component) include FC-3283 (Fluorinert) and HT-135, 200 (Garden) as well-known ones. Reduction of the global warming potential is required, and improvements in solvents are being made. However, improvement of the solvent gives an increasingly harsh environment to the sealing material, and accordingly, further improvement in the oil resistance of the sealing material is also required. By the way, as a sealing material used in a semiconductor process temperature control unit, etc., naturally, a molding material which exhibits its performance even at a low temperature, that is, can maintain rubber elasticity even at a low temperature and which has excellent low-temperature properties is required. Have been.

[0005] In addition, in the semiconductor manufacturing process, an environment in which a clean surface is always maintained at a constant high level is required. Since the necessity is extremely large, the heat medium (fluorinated oil) in the temperature control unit is required. However, it is desired to maintain the same cleanliness.
From such a viewpoint, the use of the filler has the following problems. That is, when carbon black, an inorganic metal salt, or the like is added as a filler to the molding material of the sealing material used in the temperature control unit, the filler elutes from the sealing material into the heat medium, and contamination of the heat medium is caused. May be invited. Such contamination may lower the inherent properties of the heat medium depending on the type of the filler.

[0006]

Therefore, the present invention is excellent in oil resistance and low-temperature resistance of a fluorine-based oil to a heat medium and adaptability to a clean surface in a semiconductor manufacturing process. An object of the present invention is to provide a rubber composition for a sealing material for obtaining a sealing material having excellent suitability when used in a unit, and a sealing material obtained by molding this composition.

[0007]

Means for Solving the Problems The rubber composition for a sealing material according to the present invention, which solves the above-mentioned problems, comprises 30 to 50% by weight of a propylene-derived structural unit as a rubber component and ethylidene norbornene-derived structural unit. 1 to 15% by weight, the rest of which essentially contains ethylene-propylene copolymer rubber which is a component derived from ethylene, and contains silica as a filler. A sealing material according to the present invention that solves the above-mentioned problems is obtained by molding the rubber composition for a sealing material as a material.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below, but the present invention is not limited to the following description. In general, a sealing material is often used as a joint between pipes, and in this portion, it has a function of preventing leakage of fluid from inside the pipes. An essential component of the rubber composition for a sealing material of the present invention is an ethylene-propylene-ethylidene norbornene copolymer rubber. Generally, in the ethylene-propylene-based copolymer rubber or the ethylene-propylene-diene-based copolymer rubber, when the content of the propylene-derived structural unit decreases (when the content of the ethylene-derived structural unit increases), the ethylene chain is increased. Crystallization tends to occur, and as a result, the rubber elasticity is lost. That is, since the temperature at which rubber elasticity is lost increases, elasticity of rubber is hardly exhibited in a low-temperature environment. In view of this, in the present invention, in order to obtain a rubber excellent in low-temperature properties, that is, excellent functionality under low temperatures, it is necessary to contain 30 to 50% by weight of a propylene-derived structural unit. , 33 to 48% by weight,
It is particularly preferred to contain from 32 to 45% by weight,
Most preferably, it contains 38 to 40% by weight.
When the proportion of the propylene-derived structural unit exceeds 50% by weight, it becomes difficult to secure the balance of physical properties (balance between tensile strength and elongation) required for the sealing material.
A problem arises in that respect.

[0009] Since ethylene-propylene copolymer rubber does not have a double bond, there is a problem that the processability is poor and the balance of physical properties after peroxide vulcanization is not good. In order to solve these problems, the rubber contains a diene, particularly a structural unit derived from a non-conjugated diene, as a third structural component. In the present invention, ethylidene norbornene is used as the non-conjugated diene. Ethylidene norbornene is
This is because it has an advantage that it has characteristics such as superior polymerization reactivity as compared with other dienes. When the content of this structural unit derived from ethylidene norbornene is small,
The resulting rubber or rubber composition has excessive tackiness and cannot be molded due to extremely poor processability and releasability. vice versa,
When the content of ethylidene norbornene is large, many double bonds remain in the molecule of the obtained rubber or rubber composition, and the double bond site has high chemical reactivity. Oil resistance and swelling resistance to solvents deteriorate. As a result of considering and considering these facts, in the present invention, the content of the structural unit derived from ethylidene norbornene is preferably set to 1 to 15% by weight, and 4 to 15% by weight.
It is preferably contained in an amount of 12% by weight, more preferably 8 to 12% by weight, and even more preferably 9 to 1% by weight.
It is particularly preferable to contain 1% by weight.

In order to obtain a rubber composition for a sealing material in the present invention and to obtain a sealing material obtained by molding the rubber composition for a sealing material, various additives are added to the copolymer rubber. To Such additives include fillers, co-crosslinkers, organic peroxides, colorants, and the like. In particular, as described in the section of the related art, depending on the kind of the filler, the sealing material causes contamination of the heat medium and deterioration of characteristics. In particular, at a semiconductor manufacturing site, Na, K, Ca, A
It has been considered that mixing of metals such as l, Fe, and Mg increases the product defect rate. Therefore, in the rubber composition for a sealing material of the present invention, it is preferable to reduce the content of the filler composed of the metals.

In the sense described above, silica is used as a filler as a reinforcing agent in the present invention. The addition of silica is preferably from 0 to 40 parts by weight, more preferably from 5 to 30 parts by weight, based on 100 parts by weight of the ethylene-propylene-ethylidene norbornene copolymer rubber. The co-crosslinking agent is generally used as an auxiliary agent in organic peroxide crosslinking, and specifically, sulfur, quinone dioxime, ethylene glycol dimethacrylate, divinylbenzene, diaryl phthalate, trimethacrylate, triallyl isocyanurate, trime Examples thereof include tyrolpropane trimethacrylate, 1,2-polybutadiene, metal methacrylate, and metal acrylate. Among these, a polyfunctional reactive monomer is particularly preferable, and triallyl isocyanurate and trimethylolpropane trimethacrylate are preferably used. These co-crosslinking agents are preferably added in an amount of 0 to 40 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the ethylene-propylene-ethylidene norbornene copolymer rubber.

As the organic peroxide, specifically, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, di-t-butyl peroxide, t-butyl dicumyl peroxide, benzoyl peroxide, , 5-Dimethyl-2,5-di (t-butylperoxide) hexyne-3,2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (T-butylperoxy) hexane, α,
α'-bis (t-butylperoxyisopropyl) benzene, t-butylperoxyisopropyl carbonate, parachlorobenzoyl peroxide, t-butylperbenzoate and the like can be mentioned. Ethylene-
Propylene-ethylidene norbornene copolymer rubber 10
The addition is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, based on 0 parts by weight. Among these, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, benzoyl peroxide, α, α′-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (T-
Butyl peroxyisopropyl) hexane is preferably used. At least one of these organic peroxides is used.

The coloring agent is added for the purpose of improving the external impression of the sealing material molded in the present invention. As the colorant, various known pigments such as inorganic pigments and organic pigments are used.Specifically, titanium dioxide, silica, zinc white, zinc sulfide, barium sulfate, calcium carbonate, carbon black, titanium black, synthetic Iron black, cadmium red, iron oxide, molybdenum red,
Cobalt aluminate, ferric ferrocyanide, para red, pyrazolone orange, naphthol green and the like can be mentioned. The sealing material in the present invention, as a result of consideration to suppress metal contamination which is a problem at the semiconductor manufacturing site, so as to correspond to a clean surface at the semiconductor manufacturing site, among these, inorganic pigments are preferably used, More preferably, titanium dioxide or silica is used. These colorants are preferably added in an amount of 0 to 20 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the ethylene-propylene-ethylidene norbornene copolymer rubber.

Here, the rubber composition for a sealing material in the present invention is obtained by using the above-mentioned various substances such as the above-mentioned copolymer rubber and filler as components, and the production and preparation of the composition are as follows. Like a general rubber composition,
It is carried out by using any means, for example, a mixing roll, a Banbury mixer, various kneaders and the like. Molding of the obtained rubber composition into a sealing material having a desired shape is performed similarly to molding of a general rubber composition, for example, when the rubber composition is about 100 to 200
It is carried out by applying a pressure molding method, an injection molding method, or the like while vulcanizing at a heating temperature of about 0.5 ° C. and a heating time of about 0.5 to 120 minutes.

The sealing material according to the present invention has excellent suitability for use in a temperature control unit using a fluorine-based oil as a heat medium in the semiconductor manufacturing process. Specific locations where the sealing material is used include various processing apparatuses (etching apparatus, ion implantation apparatus, stepper, CVD, etc.) in the semiconductor manufacturing process.
Equipment) and chiller unit (temperature control unit)
The main part is a heat medium pipe part connecting the pipes, and includes a joint between the pipes, a connection part between the pipe and a meter such as a flow meter, a connection part between the wafer holder and the pipe in the etching chamber, and the like.

[0016]

The present invention will be described below in more detail with reference to Examples. These embodiments are merely examples of the present invention, and the scope of the present invention is not limited to these embodiments. In the following Examples and Comparative Examples, when ethylene-propylene-ethylidene norbornene copolymer rubber was used as the base rubber of the rubber composition for a sealing material, the mixing ratio of propylene and ethylidene norbornene was changed.
In order to clarify the significance of the compounding ratio by using a copolymer rubber as a base rubber, a comparative example using a copolymer rubber without ethylidene norbornene as a base rubber was also examined for reference. The constituent components and their contents of the five types of base rubbers used in the experiments described in the following Examples and Comparative Examples are collectively described in Table 1, and the sealing rubber used in each experiment described in the following Examples and Comparative Examples The components and component ratios of the composition are summarized in Table 2.

(Examples 1 to 3 and Comparative Examples 1 and 2) A rubber composition for a sealing material was prepared according to the formulation shown in Table 2, a test piece was molded, and various physical properties were measured and evaluated. did. That is, first, the base rubber is masticated for 4 minutes at a temperature of 25 to 50 ° C. using an 8-inch roll mill, and then silica is mixed with the base rubber and titanium dioxide as a coloring agent is mixed. A rubber composition was prepared by kneading for 5 to 1 hour. Then, an organic peroxide and a co-crosslinking agent were added to the rubber composition to perform a crosslinking treatment, thereby obtaining a rubber composition for a sealing material as a crosslinked product. This cross-linking treatment went through stages of primary vulcanization (170 ° C., 15 minutes) and secondary vulcanization (170 ° C., 1 hour). Then, various physical properties were measured and evaluated using the crosslinked product (rubber composition for a sealing material). Table 3 shows the results. In Comparative Example 2, in which the base rubber 5 containing no ethylidene norbornene was added to the copolymer rubber composition, the organic peroxide vulcanization was not applicable because the structural unit derived from ethylidene norbornene was not contained, and the processability was poor. Very bad, molding of the test piece was not possible. (1) Normal physical property test According to JIS K6250, a dumbbell-shaped No. 3 type test piece was die-cut from a sheet-like cross-linked product having a thickness of 2 mm according to JIS K6251. This test piece is 500 mm
/ Min, and the tensile strength, elongation at break, and 100% tensile stress were measured. In addition, the hardness of the sheet-like crosslinked product was measured with a type A durometer hardness tester according to JIS K6253. These tests were all performed at 25 ° C. (2) Galden HT230 immersion property test A dumbbell-shaped No. 3 test piece was punched out from a sheet-like cross-linked product having a thickness of 2 mm according to JIS K6250 according to JIS K6251. This test piece was subjected to JISK6
According to H.258, it was immersed in Galden HT230 at 23 ° C. for 72 hours. After completion of the immersion, the test piece was taken out, the volume change rate was measured, and the test piece was pulled at 500 mm / min.
The elongation at break and the 100% tensile stress were measured. In addition,
According to JISK6253, the hardness of the sheet-like crosslinked product was measured with a type A durometer hardness tester. (3) TR physical property test The TR test measures the ability of a crosslinked product (rubber composition for a sealing material) that has been frozen at a low temperature after stretching to recover elasticity and shrink with increasing temperature, and to measure its crystallization and low temperature. The elastic properties are easily compared and evaluated. JISK62
In accordance with JIS K6261, a test piece was prepared from the sheet-like crosslinked product having a thickness of 2 mm, and the low-temperature property of the test piece was evaluated. The temperature at which the sheet-like crosslinked product contracts 10% from the stretched state is TR10, and the temperature at which the sheet-like crosslinked product contracts 30% and 70%, respectively, is TR30 and TR70.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

As can be seen from the above experimental results, Examples 1 to 3 using the base rubber in which the blending ratio of propylene and ethylidene norbornene in the base rubber fall within the range of the present invention.
Was excellent in both low-temperature properties and swelling resistance. In contrast, Comparative Example 1 was inferior in low-temperature properties because the content of the constituent units derived from propylene was extremely small.

[0022]

According to the present invention, it is possible to obtain a rubber composition for a sealing material, particularly a sealing material having excellent suitability for use in a temperature control unit using a fluorine-based oil as a heat medium in a semiconductor manufacturing process. And a sealing material obtained by molding the rubber composition.

Continuing from the front page (72) Inventor Takatsugu Tsutsui Nara Industrial Park, Sumikawa-cho, Gojo City, Nara Prefecture 5-2 Nippon Valqua Industry Co., Ltd. F term (reference) 4H017 AA03 AA27 AB07 AC01 AD03 AE02 4J002 BB151 DJ016 FD016 GJ02 4J100 AA02Q AA03P AS15R CA05 JA01

Claims (4)

[Claims] (1) Ethylene which is a constituent unit derived from propylene as a rubber component in an amount of 30 to 50% by weight, a constituent unit derived from ethylidene norbornene in an amount of 1 to 15% by weight, and the remainder is ethylene. -A rubber composition for a sealing material, which essentially contains a propylene copolymer rubber and contains silica as a filler. 2. A sealing material obtained by molding the rubber composition according to claim 1. 3. The sealing material according to claim 2, which is used for a temperature control unit using a fluorine-based oil as a heat medium. 4. The sealing material according to claim 3, wherein the temperature control unit is a device found in a semiconductor manufacturing process.