JP2003292651A - Nontacky elastomer molded product and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elastomer molded product having excellent nontackiness without causing staining of an apparatus as in the conventional surface treatment, and an effective and simple production method therefor. <P>SOLUTION: The nontacky elastomer molded product whose skin layer has been more highly crosslinked than the inner part is obtained by irradiating an uncrosslinked elastomer molded product with radiation having high transmission to the elastomer molded product to crosslink the whole, and then irradiating the resulting product with radiation having low transmission to the elastomer molded product to further crosslink its surface alone. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-adhesive elastomer molding and a method for producing the same.

[0002]

2. Description of the Related Art Elastomeric molded articles have no slipperiness or releasability on their surfaces, and therefore naturally adhere to each other when they are kept in contact with a metal surface for a long time. For example, if a packing made of a rubber material is attached to the metal surface of an apparatus or device, even if the packing is replaced after a long time, the packing will adhere to the metal surface, making it difficult to remove the packing. There was a problem.

Therefore, conventionally, the surface of the elastomer molded body is coated by applying a silicone-based or fluorine-based treatment liquid to the surface of the elastomer molded body and subjecting the coated surface to a cure and reaction (surface treatment). It is done to give non-stickiness to. For example, in Japanese Patent No. 2631113, as a treatment agent for imparting lubricity and releasability to the surface of a polymer molded body, a silylisocyanate and a polyester composed of a mixture of ethoxysilane triisocyanate, tetraisocyanate silane and trimethylisocyanate. It consists of and.

Further, the primary crosslinked elastomer preform is dipped in a treatment liquid in which a crosslinking agent component is dissolved in a solvent,
Alternatively, the elastomer preform is swollen with a solvent by spraying the treatment liquid, the cross-linking agent component is impregnated only in the surface portion, and heat treatment is performed to further cross-link only the surface portion (surface modification) to form a surface. Non-adhesiveness is also given by hardening.

[0005]

However, when the surface treatment is performed with a silicone-based or fluorine-based treatment liquid, the treated film is liable to peel off during use and cause contamination of the device.
In particular, when using an elastomer with a surface treatment film as packing for semiconductor manufacturing equipment or liquid crystal manufacturing equipment, the peeled surface treatment film may fall on the surface of the wafer or panel in the manufacturing equipment and contaminate them. There is.

Further, when the elastomer preform is swollen with a solvent, the cross-linking agent component is impregnated only on the surface and cured, excess surplus cross-linking agent or solvent easily remains in the elastomer preform. In some cases, the fine powder derived from the cross-linking agent may fall, or so-called outgas may be released to cause similar device contamination.

[0007] Therefore, the present invention provides an elastomer molded article excellent in non-tackiness, which does not cause device contamination as in the conventional surface treatment, and an effective and simple production method therefor. The purpose is to

[0008]

In order to solve the above-mentioned problems, the present invention is characterized in that the surface layer portion is highly radiation-crosslinked as compared with the inside, and a non-adhesive elastomer molded article and an uncrosslinked It is possible to irradiate the elastomer molded body with radiation having high permeability to the elastomer molded body to crosslink the whole, and then to radiate radiation having low permeability to the elastomer molded body to further crosslink only the surface. Provided is a method for producing a characteristic non-tacky elastomer molded body.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

In the present invention, all non-crosslinked elastomers can be those which are crosslinked by radiation. Typical examples thereof include, but are not limited to, fluorine rubber, ethylene propylene rubber, and fluorine-based thermoplastic elastomer.

The elastomer molded article to which the present invention is applied is expected to be used in fields requiring cleanliness, such as the semiconductor manufacturing field, medical field, and food field. In these fields, the elastomer molded article is used. Purity is required in itself. For example, in the case of being used in a wet process in the field of semiconductor manufacturing, there is a problem that elution of a metal element in an elastomer molded body and plasma in a dry process deteriorate the elastomer molded body, and a filler or the like becomes a factor of particles. Therefore, it is important to meet such requirements even in the elastomer molded product to which the present invention is applied.

Therefore, in the present invention, it is preferable to target an uncrosslinked elastomer that does not use a compounding material such as a crosslinking agent or a filler, for example, tetrafluoroethylene / propylene copolymer or tetrafluoroethylene / propylene / fluorine. A simple substance of vinylidene copolymer or a mixture thereof can be used.

The above-mentioned uncrosslinked elastomer is first irradiated with a highly permeable radiation A to the uncrosslinked elastomer molded body to be treated so that the entire molded body is crosslinked substantially uniformly. Here, examples of the radiation A include γ-rays, X-rays, and the like. In particular, γ-rays have a strong penetrating power and a long range, and thus are effective for crosslinking the entire uncrosslinked elastomer.

Then, radiation B having a low permeability to the uncrosslinked elastomer is irradiated to further highly crosslink only the surface layer portion. Here, examples of the radiation B include electron beams and ultraviolet rays, and among them, electron beams are preferable. Further, by the irradiation of the radiation B, the surface layer portion is highly crosslinked with a thickness of about several μm to several hundred μm, and as a result, non-adhesiveness is imparted.

In the above, the irradiation conditions of the radiation A and the radiation B are not limited, but the total dose is preferably 5 kGy to 500 kGy, and preferably 70 kGy.
Gy to 150 kGy. The radiation dose affects the properties of the elastomer molding as a sealing material. If the irradiation dose is insufficient, crosslinking will be insufficient, and it will not be possible to impart sufficient mechanical strength and physical properties such as compression set to the molded product. On the other hand, when the irradiation dose becomes excessively large, the collapse reaction of the elastomer molecules progresses to lower the molecular weight and the physical properties such as mechanical strength deteriorate. Therefore, when the irradiation dose is less than 5 kGy, crosslinking does not proceed and the compression set is hardly improved. Also, 5
If it exceeds 00 kGy, it will affect the elongation, and the elongation will be 100
% To 110%. Furthermore, the mechanical strength is reduced.

The radiation irradiation atmosphere is preferably vacuum, air, or an inert gas. In the case of γ-ray irradiation, an atmosphere in which oxygen is eliminated as much as possible, such as in vacuum or in an inert gas, is particularly preferable. If oxygen is present in the irradiation atmosphere, the crosslinking reaction may be hindered, which may cause problems such as insufficient mechanical strength of the elastomer molded body or sticky surface. In the case of electron beam irradiation, there is no problem even in air.

[0017]

EXAMPLES The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited thereto.

(Example 1) A raw material rubber of "Daiel G912" (commercial product; tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer) manufactured by Daikin Industries, Ltd. is set in a mold and hot pressed. It was preheated to a mold temperature of 170 ° C. and then pressurized and held for about 10 minutes. Next, the mold was taken out from the hot press, cooled to a mold temperature of 60 ° C. or lower, and then demolded to obtain an uncrosslinked elastomer molded body. Then, this uncrosslinked elastomer molded body was irradiated with a total dose of 120 kGy of γ-rays in a nitrogen atmosphere and then irradiated with an electron beam at an acceleration voltage of 200 keV and a total dose of 80 kGy to obtain an elastomer molded body.

(Comparative Example 1) An uncrosslinked elastomer was prepared in the same manner as in Example 1 and irradiated with γ-rays with a total dose of 120 kGy, and an elastomer molding was obtained without irradiation with electron beams.

(Example 2) "Aflas 1" manufactured by Asahi Glass Co., Ltd.
00H ”(commercial product; tetrafluoroethylene / propylene copolymer) is set in the mold, preheated using a hot press until the mold temperature reaches 170 ° C, and then pressurized and held for about 10 minutes. did. Next, the mold was taken out from the hot press, cooled to a mold temperature of 60 ° C. or lower, and then demolded to obtain an uncrosslinked elastomer molded body. Then, a total dose of 80 is applied to this uncrosslinked elastomer molded body in a nitrogen atmosphere.
After irradiating with γ-ray of kGy, the electron beam is accelerated to 200 k.
Irradiation was performed at eV and a total dose of 80 kGy to obtain an elastomer molded body.

(Comparative Example 2) An uncrosslinked elastomer molded body was prepared in the same manner as in Example 2 and irradiated with γ-rays with a total dose of 80 kGy, and an elastomer molded body was obtained without irradiation with electron beams.

(Performance Evaluation) Examples 1 and 2 and Comparative Example 1
The following items were evaluated for each of the elastomer molded products obtained in ~ 2. The results are summarized in Table 1. [Hardness] A hardness test was carried out according to JIS K6253. [Compression set (%)] According to JIS K 6262. However, the condition is 200 ° C. × 72 hours. [He leak amount (Pam3 / sec)] An elastomer molded body was cut into an O-ring shape, sandwiched between two flanges and compressed by 20%, and helium gas was 1 MPa inside the O-ring.
Loaded. Then, the helium gas leaking to the outside of the O-ring is continuously measured by a helium leak detector,
The time when the amount of helium leaked from the ring became constant was defined as the amount of helium leak. [Peeling Force (N)] An elastomer molded body is cut into an O-ring shape, sandwiched between two aluminum plates and compressed by 30%, and heated in this state at 200 ° C. for 22 hours. After heating, the entire aluminum plate was cooled to room temperature, and the peeling force of the aluminum plate was measured.

[0023]

[Table 1]

As can be seen from Table 1, the elastomer molded products of Examples 1 and 2 have a higher peeling force than the elastomer molded products of Comparative Example 1 and Comparative Example 2 because the surface layer is highly cross-linked by the electron beam. It can be seen that the non-adhesiveness is improved. Further, it can be seen that the elastomer molded bodies of Examples 1 and 2 have a He leak amount equal to or less than that of the elastomer molded bodies of Comparative Example 1 and Comparative Example 2, and also have excellent sealing properties.

[0025]

As described above, according to the present invention,
It is possible to easily obtain an elastomer molded body having excellent non-adhesiveness. Moreover, the non-adhesive elastomer molded body does not impair the mechanical properties of the elastomer itself, since the highly crosslinked portion is on the order of several to several hundreds of μm on the surface. Further, since it is a surface modification, there is no possibility that the surface treatment film peels off and the device is contaminated unlike the conventional method of forming a surface treatment film. Furthermore, since no crosslinking component or solvent is used, outgas is not emitted.

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Claims (2)

[Claims] 1. A non-adhesive elastomer molding, wherein the surface layer is highly radiation-crosslinked as compared with the inside. 2. An uncrosslinked elastomer molded body is irradiated with radiation having high permeability to the elastomer molded body to crosslink the whole, and thereafter, radiation having low permeability to the elastomer molded body is irradiated. A method for producing a non-adhesive elastomer molded body, which further comprises crosslinking only the surface.