JP2005082654A - Method for de-adhesion of fluorine rubber molding, fluorine rubber molding and sealant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform de-adhesion of a fluorine rubber molding widely used in semiconductor manufacturing apparatuses and vacuum apparatuses without deteriorating other properties in a more effective way. <P>SOLUTION: The de-adhesion of the fluorine rubber molding is performed by irradiating the fluorine rubber molding with a non-equilibrium plasma of a fluorinated olefin or of a gas containing a fluorinated alkane having a ratio of the number of fluorine atoms to the number of carbon atoms of ≤2 at a pressure of ≤1,000 Pa. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a non-adhesive method for a fluororubber molded article, a fluororubber molded article made non-adhesive thereby, and a sealing material for a semiconductor manufacturing apparatus, wafer transport container and vacuum container comprising the fluororubber molded article About.

  Rubber materials are essential as sealing materials for various devices. In particular, fluororubber sealing materials are frequently used in semiconductor manufacturing equipment and vacuum equipment. However, rubber materials often stick to the mating metal surface to be sealed, causing problems during maintenance. In particular, in a semiconductor manufacturing apparatus and a vacuum apparatus, this problem becomes significant because the sealing material is often exposed to vacuum and high temperature. The sealant sticks so strongly that it cannot be peeled off at the time of replacement, and as a result of forcibly peeling it off, the rubber powder may be rubbed off and may even adversely affect the device later. The adhesion of the rubber material causes a fatal problem such as hindering the normal operation of the apparatus, particularly in a portion where the opening and closing is frequently performed. Therefore, an effective non-adhesive technology is demanded particularly for sealing materials.

  Non-adhesive methods for rubber materials include 1) blending oil into rubber, 2) treatment with a surface treatment agent (see, for example, Patent Document 1), 3) impregnating a rubber material near the surface with a crosslinking agent. Treatment method for heating and increasing the crosslink density in the vicinity of the surface (for example, see Patent Document 2), 4) Blend of silicone rubber (for example, see Patent Document 3), 5) Covering the surface of rubber material with resin or the like (for example, Patent 6) Filling rubber with fluororesin powder or the like (see, for example, Patent Document 5) is known.

  However, the method 1) causes problems such as contamination due to oil leaching and a decrease in strength of the material itself. Even in the method 2), problems such as a decrease in non-adhesiveness due to the removal of the surface treatment agent and contamination of the seal surface and fluid cannot be ignored. According to the method 3), it can be made non-adhesive to some extent, but it requires a complicated processing operation. In addition, as shown in examples (comparative examples) described later, the effects are not always satisfactory. The method 4) also has drawbacks such as insufficient non-adhesiveness and reduced strength of the fluororubber material. The method 5) has problems such as detachment / peeling of the resin layer and a decrease in rubber elasticity due to the presence of the resin layer. Further, in the simple filling method as in 6), the resin powder that appears on the surface layer is small, and sufficient non-adhesiveness cannot be exhibited. If the resin powder filling amount is increased in order to solve this point, problems such as a decrease in the elasticity and strength of the rubber material and a deterioration in the crosslinkability are caused.

In addition, in order to avoid the above problem and to make it non-adhesive, the rubber material is also irradiated with a specific kind of plasma. For example, a method of treating the surface of a rubber material with nitrogen plasma (see Patent Document 6), a treatment method of ashing a nitrile rubber surface with oxygen plasma (see Patent Document 7), and treating silicon rubber with plasma to make it non-adhesive And the like (see Patent Document 8).
JP-A-1-301725 Japanese Patent Publication No.5-21931 JP-A-5-339456 Japanese Unexamined Patent Publication No. 1-141909 Japanese Patent No. 3009676 JP 59-71336 A Japanese Patent Publication No.1-57136 JP-A-4-209633

  However, in the conventional non-adhesion method using plasma irradiation, the non-adhesion effect may not be exhibited depending on the rubber material and the type of plasma. For example, in Japanese Patent Publication No. 6-025261, Japanese Patent Laid-Open No. 5-220208, Japanese Patent Laid-Open No. 5-309787, etc., there is a description that the adhesiveness rather increases when the rubber is irradiated with plasma such as oxygen or He. is there. Even in the same plasma treatment, the effect to be manifested is completely different depending on the combination of the gas type and the object to be irradiated, the irradiation conditions and the like. As shown in the examples described later, even in the plasma treatment of fluororubber, if the irradiation conditions are inappropriate, the non-tackifying effect does not appear. Furthermore, if the selection of the plasma type is wrong, there arises a problem that the sealing property is lowered while the surface is made non-adhesive.

  The present invention has been made in view of such a situation, and performs non-adhesion of a fluororubber molded product frequently used in a semiconductor manufacturing apparatus, a vacuum apparatus or the like more effectively without impairing other characteristics. For the purpose.

  The present inventors have repeatedly studied to solve the above problems, and after irradiating the fluororubber molded product with a specific fluorocarbon compound plasma, or applying or impregnating a specific fluorocarbon compound to the fluororubber molded product It has been found that by irradiating with argon or oxygen plasma, the fluororubber molded article becomes non-tacky and the sealing performance does not deteriorate.

  That is, the present invention is characterized by irradiating a fluororubber molded article with non-equilibrium plasma of a gas having a pressure of 1000 Pa or less containing a fluorinated olefin or a fluorinated alkane having a ratio of fluorine atoms / carbon atoms of 2 or less. This is a non-adhesive method for a fluororubber molded product.

  The present invention is also characterized in that the fluororubber molded article is coated with or impregnated with a fluoroolefin or a fluoroalkane having a ratio of fluorine atoms / carbon atoms of 2 or less, and then irradiated with non-equilibrium plasma. This is a non-adhesive method for the fluororubber molded article.

  The present invention further includes a fluororubber molded article obtained by the above-described non-adhesive method, and each sealing material for a semiconductor manufacturing apparatus, wafer transport container and vacuum container made of the fluororubber molded article.

  According to the treatment method according to the present invention, the fluororubber molded article can be made non-adhesive without impairing physical properties such as sealing properties. The effects of the present invention are remarkable in view of the fact that it is difficult to achieve both of these physical properties with conventional treatment methods.

  Hereinafter, the present invention will be described in detail.

  In the present invention, two important points are the use of a specific fluorocarbon compound and the use of non-equilibrium plasma.

  Plasma is an independent collection of electrons, ions, radicals, excited molecules, etc., and maintains an aggregated state for many times the average collision time between particles. Among these, gas temperature and electron temperature Those in which only the former is at a high temperature are referred to as “non-equilibrium plasma” or “low temperature plasma” (see, for example, edited by Yoshihito Nagata, published by Industrial Books, Low Temperature Plasma Material Chemistry). Unlike the equilibrium plasma, this non-equilibrium plasma has a low gas temperature, so that the internal structure of the fluororubber molded article is less likely to cause deterioration in physical properties.

  The non-equilibrium plasma can be easily obtained in the form of glow discharge, corona discharge, arc discharge, dark discharge, or the like by direct current discharge in a desired gas or irradiation with low frequency, high frequency, or microwave. Among them, glow discharge in a low vacuum state is frequently used because it can generate uniform plasma. In particular, an apparatus using a high frequency such as a radio wave of 13.56 MHz is general, and in the present invention, either high frequency plasma of a capacitive coupling type or an inductive coupling type can be used. Of course, it is possible to use various commercially available plasma generators. However, in the present invention, it is preferable to use a low-frequency power source of 1 to 500 kHz, particularly 10 to 100 kHz, for the purpose of suppressing the etching of fluororubber. Non-equilibrium plasma is used to hydrophilize resins and fibers (JP-A-11-314310, etc.), impart adhesion (JP-A-62-248098, JP-A-10-30761, etc.), and fluorination treatment of hydrocarbon rubber (JP-A-6-314 9803, Japanese Patent Laid-Open No. 6-19453, etc.) and a fluorocarbon protective film formation on a semiconductor device (Japanese Patent Laid-Open No. 2002-220668). It will be easy to choose.

  In the first aspect of the present invention, a fluorinated olefin or a gas containing a fluorinated alkane having a ratio of fluorine atoms / carbon atoms of 2 or less is used as the plasma gas. As shown in the examples described later, the fluororubber molded article is non-adhesive even when non-fluorinated carbon-based plasma or fluorocarbon plasma having the number of fluorine atoms / number of carbon atoms> 2 and having no double bond is used. It is not converted. Or the sealing performance is significantly reduced. On the other hand, by using non-equilibrium plasma of a gas containing a specific fluorocarbon compound according to the present invention, the fluororubber molded article can be made non-adhesive with almost no deterioration in sealing performance.

Fluorinated olefins are known per se. In the present invention, the “olefin” includes a compound having a plurality of double bonds such as diolefin. Specific examples of the fluorinated olefin include, but are not limited to, hexafluoropropylene (C ₃ F ₆ ) and hexafluorobutadiene (C ₄ F ₆ ). These compounds are commercially available from Daikin Industries, Ltd., Showa Denko Co., Ltd., etc., and can also be used in the present invention.

Fluorinated alkanes having a fluorine atom / carbon atom ratio of 2 or less are also known. Examples include, but are not limited to, CH ₂ F ₂ , C ₂ H ₂ F ₄ , C ₂ H ₃ F ₃ , C ₂ H ₄ F ₂ , perfluorocyclobutane, CHClF _{2 and the} like. These compounds are commercially available from Daikin Industries, Ltd., Asahi Glass Co., Ltd., etc., and can also be used in the present invention.

In the present invention, the above compounds (hereinafter collectively referred to as “fluorinated carbon compounds”) can be used alone or in combination. If desired, it may be mixed with a gas such as H ₂ , O ₂ , CF ₄ or the like. Preferably, hexafluoropropylene, hexafluorobutadiene, CH ₂ F ₂ , CH ₃ CF ₃ , CH ₃ CHF ₂ , CF ₃ CH ₂ F, or CHCl ₂ is used. In particular, hexafluorobutadiene is preferable.

  From these gases, a desired non-equilibrium plasma can be created, for example, by low frequency discharge. The frequency is not particularly limited, but is preferably about 1 to 500 kHz, particularly about 10 to 100 kHz. Other irradiation conditions are not particularly limited, and can be arbitrarily set according to the desired degree of non-adhesive properties and the type of gas used. Here, if the discharge output (plasma power) is too low, the non-adhesive effect may not be exhibited. On the other hand, when high-power non-equilibrium plasma is irradiated for a long time, the sealing performance may be lowered. Preferably, when irradiated at a power of about 1 to 500 W, more preferably 5 to 200 W, particularly preferably 10 to 100 W for 0.1 to 30 minutes, particularly 0.5 to 10 minutes, the sealability is hardly reduced. Can be tackified.

  The gas pressure during the plasma irradiation is 1000 Pa or less. If the pressure at the time of irradiation is more than this, the non-adhesive effect is hardly exhibited, or there is a possibility that a large variation occurs in the physical properties of the fluororubber molded body for each irradiation. The gas pressure at the time of plasma irradiation is preferably 0.01 to 500 Pa, more preferably 0.1 to 100 Pa.

In the second embodiment of the present invention, first, a fluorinated olefin or a fluorinated alkane having a ratio of fluorine atoms / carbon atoms of 2 or less is applied to or impregnated on the fluororubber molded article. As the fluorinated olefin or the fluorinated alkane having a fluorine atom / carbon atom ratio of 2 or less, any of the fluorocarbon compounds listed above can be used. Other than these, compounds having higher boiling points such as octafluorocyclopentene (C ₅ F ₈ ), perfluorobutyl ethylene (C ₄ F ₉ CH═CH ₂ ), perfluorohexyl ethylene (C ₆ F ₁₃ CH═CH _2). ) Etc. can also be used. These fluorocarbon compounds may be applied to or impregnated into a fluororubber molded product, alone or in combination of a plurality of types, or diluted with a solvent. There are no particular limitations on the coating method and impregnation method, and various conventional methods can be used. For example, brush coating, spray coating, dipping (immersion) and the like can be mentioned, but not limited thereto.

  However, dipping is preferably employed. Further, from the viewpoint of increasing the cleanliness of the treated fluoro molded article, dilution with a solvent should be avoided as much as possible. Particularly preferably, the fluororubber molded article is directly immersed in a fluorocarbon compound having a boiling point not higher than room temperature. There is no particular limitation on the immersion conditions, but when a low-boiling fluorocarbon compound is used, it is preferable to use a pressure vessel. The immersion temperature and time can be arbitrarily set according to the types of the fluororubber molded product and the fluorocarbon compound. However, since general-purpose fluororubber may cause a decrease in strength when immersed in the fluorocarbon compound, it is preferably immersed at room temperature for about 1 minute to 24 hours.

In the second embodiment of the present invention, the non-equilibrium plasma is irradiated to the fluororubber molded article thus coated or impregnated with the fluorocarbon compound. No particular limitation is imposed on the plasma gas species used here, preferably using oxygen, argon, nitrogen, water, a CF ₄ or the like. In particular, argon plasma is preferable. There is no restriction | limiting in particular in irradiation conditions, According to the kind of used fluorocarbon compound, it can set arbitrarily. However, if the plasma output is too low, the non-adhesive effect may not be exhibited, and if it is too high, the sealing performance may be reduced. When non-equilibrium plasma of 1 to 200 W, particularly 10 to 100 W, is irradiated for 0.1 to 30 minutes, particularly 0.5 to 5 minutes, non-adhesion can be achieved without substantially reducing the sealing property. Unlike the first embodiment, the gas pressure at the time of irradiation is not particularly limited, but is preferably 1000 Pa or less, more preferably 0.01 to 500 Pa, and particularly preferably 0.1 to 100 Pa.

Although this invention is not limited to a specific theory, formation of the surface fluoride film by plasma polymerization can be considered as a reason where this invention has an effect. The fluorocarbon compound will be polymerized in a plasma atmosphere, and a highly fluorinated polymer film will be formed on the surface of the fluororubber molded product, which will cause non-adhesion. In addition, the fluorocarbon compound used in the present invention has higher polymerizability than plasma such as CF ₄ and has a small etching action, so that the sealing property of the fluororubber molded article will not be lowered. In the first aspect of the present invention, it is presumed that plasma polymerization in a narrow sense is proceeding, and in the second aspect, plasma-initiated polymerization is proceeding.

  The detackifying method of the present invention can be applied to all of various known fluororubber molded articles. Examples of the raw material fluororubber include hexafluoropropylene / vinylidene fluoride binary copolymer, tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride terpolymer, tetrafluoroethylene / propylene copolymer, tetrafluoroethylene / A propylene / vinylidene fluoride copolymer, a polymer having a double bond attached thereto, a polymer having a perfluoroalkoxy group, a fluorosilicone rubber, and the like are exemplified, but the invention is not limited thereto. These fluororubbers may also be crosslinked by any method such as polyols, polyamines, peroxides, and γ rays.

  In order to secure the effect of the present invention, it is preferable to wash the fluororubber molded product before the non-adhesive treatment of the present invention. The cleaning method is arbitrary. For example, a method of immersing the fluororubber molded body in a solvent such as ethanol, propanol, water, a method of further washing with stirring or ultrasonic cleaning, a method of flowing or spraying the solvent etc. on the surface of the fluororubber molded body, Although the method of wiping off is mentioned, it is not limited to these. For general applications, it may be appropriate to perform ultrasonic cleaning with ethanol or propanol, and ultrapure water cleaning for applications that require special cleanliness.

  The non-tackifying treatment of the present invention is hardly accompanied by a decrease in sealing performance and does not contaminate the rubber molded body. Therefore, a rubber material suitable for a semiconductor manufacturing apparatus, food, or medical use can be obtained. The present invention also includes a sealing material for a semiconductor manufacturing apparatus, a sealing material for a wafer transfer container, and a sealing material for a vacuum container, which are made of the fluororubber molded article.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example.
[Examples 1 to 9, Comparative Examples 1 to 4]
(Sample preparation)
100 parts by weight of Florel FC-2145 (vinylidene fluoride / hexafluoropropylene copolymer manufactured by Sumitomo 3M), 5 parts by weight of magnesium oxide, 30 parts by weight of MT-CB (carbon black manufactured by CANCARB), curative 20 (polyol crosslinking accelerator manufactured by DuPont Dow Elastomer Co., Ltd., main component: triphenylbenzylphosphonium salt) and curative 30 (polyol crosslinker manufactured by DuPont Dow Elastomer Co., Ltd., main component: bisphenol AF) 4 parts by weight was kneaded with a biaxial roll. This was placed in a 200 ° C. mold and pressed at 200 kgf / cm ² with a 200 ° C. press for 15 minutes to form a P-26 O-ring. Further, after secondary crosslinking at 200 ° C. for 20 hours in an oven, ultrasonic cleaning was performed in ethanol for 15 minutes.

The obtained O-ring was irradiated with non-equilibrium plasma having an oscillation frequency of 40 kHz under the conditions shown in Table 1. Tetra30-LF (manufactured by Deiner Electronic) was used as the plasma irradiation apparatus, and the electrode spacing was 200 mm. The O-ring after irradiation was subjected to ultrasonic cleaning in ethanol for 3 minutes and dried, and then the following evaluation was performed (Examples 1 to 9, Comparative Examples 1 to 4). Further, for comparison, the following evaluation was performed without irradiating the obtained O-ring with non-equilibrium plasma (control example).
(Adhesion evaluation)
In order to evaluate adhesiveness, a tensile peel test according to JIS K6854 was performed using three O-rings. That is, as shown in FIG. 1, the O-ring 1 is sandwiched between a pair of jigs 10a and 10b formed by bending a 60 mm × 45 mm × 2.5 mm thick aluminum plate into an L-shaped cross section, and the jigs 10a and 10b The entire flat portion was sandwiched between SUS plates (not shown) and compressed by 30%, and maintained in a compressed state at 200 ° C. for 22 hours. After releasing pressure and allowing to cool, it was pulled in the direction of the arrow at 100 mm / min, the load required for peeling was measured, and the median value was taken as the adhesive strength.
(Sealability evaluation)
In addition, a He leak test according to JIS Z2331 was performed in order to evaluate the sealing performance. That is, as shown in FIG. 2, the O-ring 1 is accommodated in the holder 120 of the housing 110 of the leak test apparatus 100, the inside is decompressed to 1.6 to 1.8 Pa, and then He gas is sent from the He cylinder 130. A He pressure of 1.0 kgf / cm ² was applied. The O-ring 1 is fitted on the measuring unit 140a of the He detector 140 (UL-200 manufactured by LEYBOLD), and the amount of He gas flowing into the measuring unit 140a was measured. Then, a substantially stable value after 120 minutes was adopted as the amount of He leak.

  Table 1 shows the plasma irradiation conditions and the evaluation results.

As shown in Table 1, according to the present invention, all of the O-rings of the examples irradiated with non-equilibrium plasma using fluorinated olefins or fluorinated alkanes having a ratio of fluorine atoms / carbon atoms of 2 or less are sealable. The adhesive strength is reduced without decreasing. On the other hand, in the O-ring of the comparative example treated with other plasma, the non-sticking effect is hardly exhibited or the amount of He leak is remarkably increased.
[Example 10]
Seven O-rings produced in the same manner as in Examples 1 to 9 were placed in a pressure vessel, and 60 g of hexafluorobutadiene was injected therein. After standing for 16 hours, the pressure was released and the O-ring was taken out. Five minutes later, 100 W Ar plasma was irradiated under a pressure of 30 ± 5 Pa. The irradiation time was 3 minutes on one side, left for 1 minute, then turned over and again 3 minutes. The treated O-ring was ultrasonically cleaned in ethanol for 3 minutes, and then the adhesive strength evaluation and the sealing performance evaluation were performed in the same manner. The results are shown in Table 2.
[Example 11]
The same operation as in Example 10 was performed except that CF ₃ CH ₂ F was used instead of hexafluorobutadiene. The results are shown in Table 2.

  As shown in Table 2, in accordance with the present invention, after impregnating a fluorinated olefin or a fluorinated alkane having a ratio of fluorine atoms / carbon atoms of 2 or less, the non-equilibrium plasma is irradiated to reduce the sealing performance. It is clear that non-adhesion is manifested without much.

It is a conceptual diagram of the testing apparatus used for adhesive evaluation in an Example. It is a conceptual diagram of the leak test apparatus used for sealing performance evaluation in the Example.

Explanation of symbols

1 O-ring 10a, 10b Jig 100 Leak test device 110 Housing 120 Holder 130 He cylinder 140 He detector

Claims (7)

Fluororubber molded article characterized by irradiating a non-equilibrium plasma of a gas having a pressure of 1000 Pa or less, containing a fluorinated olefin or a fluoroalkane having a fluorine atom / carbon atom ratio of 2 or less. Non-sticking method. Fluororubber molding characterized by irradiating non-equilibrium plasma after applying or impregnating a fluororubber molding with a fluoroolefin or a fluoroalkane having a ratio of fluorine atoms / carbon atoms of 2 or less A method of non-adhesion of the body. Fluorinated olefins or fluorinated alkanes having a fluorine atom / carbon atom ratio of 2 or less are selected from hexafluorobutadiene, CH ₂ F ₂ , CH ₃ CF ₃ , CH ₃ CHF ₂ , CF ₃ CH ₂ F and CHCl ₂ The method for detackifying a rubber molded article according to claim 1 or 2, wherein the compound is one or more compounds. A fluororubber molded article treated by the detackifying method according to any one of claims 1 to 3. A sealing material for semiconductor manufacturing equipment, comprising the fluororubber molded product according to claim 4. A sealing material for a wafer transfer container, comprising the fluororubber molded product according to claim 4. A sealing material for a vacuum vessel, comprising the fluororubber molded product according to claim 4.

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