JP5780825B2 - Elastomer molded body - Google Patents

Description

  The present invention relates to a perfluoroelastomer composition suitable as a sealing material for a device used in a thermal diffusion process, a plasma CVD process, and the like, and a molded body thereof.

  Perfluoroelastomer moldings are often used in semiconductor manufacturing equipment and the like because of their excellent chemical stability. Perfluoroelastomer molded bodies are suitably used in thermal diffusion furnaces, plasma CVD apparatuses, and plasma etching apparatuses that require heat resistance.

  In general, perfluoroelastomer moldings exhibit excellent chemical resistance and heat resistance due to the stability and inertness of the copolymerized perfluorinated monomer units that constitute the main part of the polymer main chain. The perfluoroelastomer composition can be obtained mainly by peroxide crosslinking using a peroxide and a co-crosslinking agent. In addition, in the perfluoroelastomer molded body, carbon black is blended as a filler to improve mechanical properties.

International Publication Number WO2000 / 000054 JP 2011-32465 A

  However, in the thermal diffusion process and the plasma CVD process, fluorine decomposition products are generated, and these decomposition products are applied to devices such as a thermal diffusion furnace and peripheral devices connected to the devices, for example, sealing materials used in exhaust devices. There is a problem of influencing and causing deterioration of the sealing material.

International Publication No. WO2000 / 042093 discloses a crosslinkable elastomer composition comprising a carbon black filler having an impurity metal content of 300 ppm or less by an ashing analysis method and an average particle size of 700 μm or less and a crosslinkable elastomer component. A molded product obtained by cross-linking molding is disclosed, wherein the molded product has an impurity metal content of 100 ppm or less by an ashing analysis method and an increase rate of particles by oxygen plasma irradiation of 500% or less. ing. Further, it is described that the carbon black filler blended in the crosslinkable elastomer composition is preferably a carbon black filler having a specific surface area of 3 m ² / g or more and a DBP oil absorption of 15 ml / 100 g or more from the viewpoint of processability. . However, the elastomer molded product described in WO2000 / 042093 suppresses the generation of particles (impurity fine particles) from the elastomer molded product in a dry process such as plasma etching in a semiconductor manufacturing process, or is washed. It solves the metal elution problem of the elastomer molded product used in the wet process, and does not solve the resistance to the fluorine decomposition product.

Japanese Patent Application Laid-Open No. 2011-32465 discloses a rubber composition containing 5 to 60 parts by mass of carbon black per 100 parts by mass of vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer rubber. A rubber member is disclosed. It is described that the carbon black preferably has a nitrogen specific surface area of 5 to 80 m ² / g and a DBP oil absorption of 150 ml / 100 g or less from the viewpoint of mixed processability and moldability. However, the rubber member disclosed in Japanese Patent Application Laid-Open No. 2011-32465 is excellent in reducing the adhesion of abrasion powder generated from the rubber member to the conveyed product and in resistance to phosphoric acid, hydrochloric acid, nitric acid, etc. It does not solve the resistance to.

  Accordingly, an object of the present invention is to provide a perfluoroelastomer composition exhibiting excellent resistance to a decomposition product of fluorine and a molded product thereof.

  Under such circumstances, the present inventor has conducted intensive studies, and as a result, an elastomer molded product obtained by crosslinking a perfluoroelastomer composition blended with a specific carbon black can be used for the generation of fluorine generated in a thermal diffusion process or a plasma CVD process. It has been found that it has excellent resistance to the decomposition products, and has completed the present invention.

That is, the present invention provides a perfluoroelastomer composition containing a perfluoroelastomer component and carbon black having a nitrogen adsorption specific surface area of 50 m ² / g or more and 1300 m ² / g or less.

  The present invention also provides an elastomer molded article obtained by crosslinking and molding the perfluoroelastomer composition.

  The elastomer molded product of the present invention exhibits excellent resistance to fluorine decomposition products. For this reason, when the elastomer molded product of the present invention is used as a sealing material for sealing an apparatus used in a thermal diffusion process or a plasma CVD process, a stable sealing property can be exhibited over a long period of time.

It is a figure which shows the shape of the test body used for the fluorine gas exposure test, (A) is a perspective view, (B) is a front view, (C) is a side view. It is a figure which shows the shape of the test body after the fluorine gas exposure test in the comparative example 1, (A) is a front view, (B) is the figure seen along the XX line of FIG. 2 (A). It is a process image for calculating | requiring the radius of the cross-sectional corner | angular part in Example 2. FIG. It is a processed image for calculating | requiring the radius of the cross-sectional corner | angular part in Example 3. FIG. It is a processing image for calculating | requiring the radius of the cross-sectional corner | angular part in Example 4. FIG. It is a processing image for calculating | requiring the radius of the cross-sectional corner | angular part in Example 5. FIG. It is a process image for calculating | requiring the radius of the cross-sectional corner | angular part in Example 6. FIG. It is a processing image for calculating | requiring the radius of the cross-sectional corner | angular part in the comparative example 1. It is a processing image for calculating | requiring the radius of the cross-sectional corner | angular part in the comparative example 2.

The perfluoroelastomer composition of the present invention (hereinafter also simply referred to as “elastomer composition”) contains a perfluoroelastomer component. Perfluoroelastomer component from (a) tetrafluoroethylene, (b) perfluoro _(C 1 -C ₅ alkyl vinyl ether) and / or perfluoro _(C 3 _{-C 11} alkoxyalkyl vinyl ethers), (c) a cure site monomer It is a copolymer.

Component (b), perfluoro (C ₁ -C ₅ alkyl vinyl ether), is a perfluoroalkyl vinyl ether having 1 to 5 carbon atoms in the alkyl group, specifically, perfluoromethyl vinyl ether, perfluoroethyl. Examples include vinyl ether and perfluoropropyl vinyl ether, and more preferred is perfluoromethyl vinyl ether.

In addition, perfluoro (C ₃ -C ₁₁ alkoxyalkyl vinyl ether) as component (b) is a perfluoroalkoxyalkyl vinyl ether having 3 to 11 carbon atoms in the side chain, that is, the total number of carbon atoms of the alkoxyl group and the alkyl group. a perfluoroalkoxy vinyl ether of 3 to 11, _{specifically, CF 2 = CFOCF 2 CF (} CF 3) OC n F 2n + 1 (n: 1~5), CF 2 = CFO (CF 2) 3 OC _n F _{2n + 1} (n: 1 to 5), CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ O) _m C _n F _{2n + 1} (n: 1 to 5, m: 1 to 3) CF ₂ = CFO ( _{CF 2) 2 OC n F 2n} + 1 (n: 1~5) , and the like. These (b) components can be used individually or in combination of 2 or more types as appropriate.

(C) As a cure site monomer, a cure site monomer containing iodine or bromine or a cure site monomer containing a cyano group may be mentioned. Examples of the curing site monomer containing iodine or bromine include CF ₂ ═CF (CF ₂ ) _n I, CF ₂ ═CF (CF ₂ ) _n Br, I (CF ₂ ) _n I, and the like. Examples of the cured site monomer containing a cyano group include cyano group-containing perfluorovinyl ether. For example, CF ₂ = CFO (CF ₂ ) _n OCF (CF ₃ ) CN (n: 2 to 4), CF ₂ = CFO (CF ₂ ) _n CN (n: 2 to 12), CF ₂ = CFO [CF ₂ CF (CF ₃ ) O] _m (CF ₂ ) _n CN (n: 2, m: 1 to 5), CF _{2 = CFO [CF 2 CF (} CF 3) O] m (CF 2) n CN (n: 1~4, m: 1~2), CF 2 = CFO [CF 2 CF (CF 3) O] n CF ₂ CF (CF ₃ ) CN (n: 0 to 4) and the like. Of these, perfluoro (8-cyano-5-methyl-3,6-dioxa-1-octene) is preferable.

The compounding ratio, (a) tetrafluoroethylene 50 to 75 mol%, preferably 60 to 75 mol%, (b) perfluoro (C ₁ -C ₅ alkyl vinyl ether) and / or perfluoro _{(C 3} - C ₁₁ alkoxyalkyl vinyl ether) is from 49.8 to 25 mol%, preferably 39.8 to 25 mol%, (c) a cure site monomer is 0.2 to 5 mol%, preferably 0.5 to 3 mol% is there.

Carbon black blended in the elastomer composition has a nitrogen adsorption specific surface area of 50 m ² / g or more and 1300 m ² / g or less, preferably 60 m ² / g or more and 1000 m ² / g or less, particularly 65 m ² / g or more and 200 m. ² / g or less. When the nitrogen specific surface area of carbon black is less than 50 m ² / g, the surface of the elastomer molded body is easily dissolved when exposed to fluorine gas heated to a high temperature. In addition, a nitrogen adsorption specific surface area is a specific surface area (JISK 6217) calculated | required by S-BET type | formula from nitrogen adsorption amount.

Carbon black to be incorporated into the elastomer composition, DBP oil absorption of preferably 90cm ^3/100 g or more, 600 cm ^3/100 g or less, particularly preferably 95cm ^3/100 g or more, 400 cm ^3/100 g or less, more preferably 95cm ³ / 100g or more, and less than 200cm ³ / 100g. DBP oil absorption of carbon black is less than 90cm ^3/100 g, an elastomer molded body, when exposed to the fluorine gas heated to a high temperature, tends to dissolve the surface. The DBP oil absorption is the amount of DBP (dibutyl phthalate) absorbed by 100 g of carbon black (JIS K6221).

  Examples of such carbon black include furnace black and acetylene black such as SAF carbon black, ISAF carbon black, HAF carbon black, and FEF carbon black. Among these, acetylene black is preferable because it is excellent in fluorine gas resistance.

  The carbon black is 5 parts by weight or more, preferably 10 parts by weight or more and 30 parts by weight or less, particularly preferably 12 parts by weight or more and 25 parts by weight or less, more preferably 14 parts by weight with respect to 100 parts by weight of the perfluoroelastomer component. More than 20 parts by weight. When the blending amount of the carbon black is less than 5 parts by weight with respect to 100 parts by weight of the perfluoroelastomer component, when the elastomer molded body is exposed to fluorine gas heated to a high temperature, the surface is easily dissolved.

  In the elastomer composition of the present invention, various additives corresponding to the requirements of the application location can be blended as optional components. Examples of such various additives include stabilizers, plasticizers, lubricants, and processing aids. Moreover, the compounding quantity of various additives can be suitably determined in the range which does not impair the effect of this invention.

  The elastomer composition of the present invention contains a crosslinking agent. What is necessary is just to select suitably the crosslinking agent mix | blended with the elastomer composition of this invention according to the kind of crosslinkable group of an elastomer. Examples of the crosslinking reaction include known crosslinking systems such as peroxide crosslinking systems, polyol crosslinking systems, polyamine crosslinking systems, triazine crosslinking systems, oxazole crosslinking systems, imidazole crosslinking systems, thiazole crosslinking systems, and radiation crosslinking systems.

  The amount of the crosslinking agent is usually 0.05 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the perfluoroelastomer component. If the blending amount of the crosslinking agent is less than 0.05 parts by weight, the elastomer is not sufficiently crosslinked, and if it exceeds 10 parts by weight, the physical properties of the crosslinked product are deteriorated.

  The elastomer composition of the present invention is useful as a molding material for various molded articles. The elastomer composition of the present invention is particularly used for a molded body for sealing a thermal diffusion furnace of a semiconductor wafer. In the elastomer composition of the present invention, the above-described components such as the perfluoroelastomer component, the carbon black, and the crosslinking agent are mixed using a normal elastomer kneading machine such as an open roll, a Banbury mixer, a kneader, or the like. Can be prepared.

  The elastomer molded body of the present invention is obtained by crosslinking and molding an elastomer composition. That is, the perfluoroelastomer molded article of the present invention can be obtained by molding the obtained kneaded product into a predetermined shape, for example, an O-ring, and then crosslinking by heating. The crosslinking condition may be based on a known method. For example, it is placed in a mold and kept under pressure at 120 to 220 ° C. for 1 to 60 minutes, followed by press crosslinking, then in a furnace at 120 to 260 ° C. in a furnace. The method etc. which perform oven bridge | crosslinking by hold | maintaining for 5 to 50 hours are mentioned.

  When the elastomer molded body of the present invention is used as a sealing material for sealing a semiconductor wafer thermal diffusion furnace, for example, an O-ring, the effect of the present invention is remarkably exhibited. The semiconductor wafer thermal diffusion furnace performs thermal diffusion of impurities to the wafer in the process of manufacturing the semiconductor wafer, and may be, for example, an impurity diffusion apparatus disclosed in JP-A-6-45294. Further, the semiconductor wafer thermal diffusion furnace includes, for example, an exhaust device around the thermal diffusion furnace. When the elastomer molded body of the present invention is used as, for example, an O-ring as a sealing material for these thermal diffusion furnaces, the surface of the O-ring does not melt or damage even when exposed to high-temperature fluorine gas generated in the thermal diffusion furnace. A stable sealing function can be expressed over a long period of time.

(Example)
EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.

(Manufacture of elastomer)
In a stainless steel autoclave having a capacity of 500 ml, 200 ml of distilled water, 2.5 g of ammonium perfluorooctanoate and 4.4 g of Na ₂ HPO ₄ · 12H ₂ O were charged, and then the inside was purged with nitrogen gas, and then the pressure was reduced. After cooling the autoclave to 50 ° C., 32 g of tetrafluoroethylene, 68 g of perfluoromethyl vinyl ether and 6.4 g of perfluoro-8-cyano-5-methyl-3,6-dioxa-1-octene were charged and the temperature was raised to 80 ° C. After warming, 0.75 g of sodium sulfite and 3.75 g of ammonium persulfate were charged as 25 ml aqueous solutions, respectively, and polymerization was started. After continuing the polymerization for 20 hours, the unreacted gas was purged, the aqueous latex formed there was taken out, salted out with a 10% sodium chloride aqueous solution, and then dried to obtain 44 g of a crumb rubber-like terpolymer. It was. From the results of infrared absorption analysis, this ternary copolymer was found to contain 62 mol% tetrafluoroethylene, 37 mol% perfluoromethyl vinyl ether and perfluoro-8-cyano-5-methyl 3,6-dioxa-1-octene. (Characteristic absorption of cyano group 2268 cm ⁻¹ ) It had a copolymer composition of 1.0 mol%.

(Manufacture of O-rings)
100 parts by weight of the elastomer obtained by the above production method, 1 part by weight of the crosslinking agent 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, and 5 parts by weight of the following “carbon black A” are kneaded with an open roll. After that, heat treatment was performed at a temperature of 190 ° C. for 30 minutes to perform primary crosslinking, and then heat treatment was performed at 240 ° C. for 48 hours to perform secondary crosslinking and molding. The shape of the molded body was an O-ring (AS568B-214). Carbon black is obtained by calculating the nitrogen adsorption specific surface area and the DBP oil absorption amount according to JIS K 6217 (1997), and the values are manufacturer catalog values. The obtained O-ring was subjected to the following fluorine gas exposure test and evaluated for resistance to high-temperature fluorine gas. The results are shown in Table 1.

“Carbon Black A”;
"Denka Black" (manufactured by Denki Kagaku Kogyo; acetylene black)
Nitrogen adsorption specific surface area 69m ² / g, DBP oil absorption 190cm ³ / 100g

(Fluorine gas exposure test)
An AS568B-214 size (diameter D is 3.53 mm) O-ring was cut into a linear body with a circular cross section, and a test piece was obtained from which a line segment having a length L of 10 mm was cut (see FIG. 1). Then, the test piece was set in the chamber, 20% concentration of fluorine gas (80% nitrogen) was introduced so that the pressure became 500 torr, and then the chamber was heated to 250 ° C. and held for 2 hours.

(Evaluation method)
Observe the O-ring surface and edge after the fluorine gas exposure test. In the case of an O-ring in which melting by high-temperature fluorine gas proceeds, melting occurs at the corners of the end face of the O-ring as shown in FIG. 2B, and the end face approaches a spherical surface as the progress of melting progresses. For this reason, the tolerance with respect to high temperature fluorine gas was evaluated by measuring the radius R of the corner | angular part of the end surface of an O-ring. The corner radius R was determined by image processing of the O-ring after the test by photographing the cut surface along the line XX in FIG. 2 (A). Therefore, the greater the radius (mm), the lower the resistance to high-temperature fluorine gas, and the smaller the radius (mm), the better the resistance to high-temperature fluorine gas.

  An O-ring was prepared in the same manner as in Example 1 except that the following “carbon black B” was used instead of “carbon black A”. Carbon black is obtained by calculating the nitrogen adsorption specific surface area and the DBP oil absorption amount according to JIS K 6217 (1997), and the values are manufacturer catalog values. The obtained O-ring was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Moreover, the image for calculating | requiring the radius of the end surface corner | angular part of the test body after a fluorine gas exposure test is shown in FIG. In FIG. 3, the black portion is a test body, and the white portion is a circle added by image processing having a corner radius.

“Carbon Black B”;
"Shio Black IP 1500" (SAF carbon black) (Cabot)
Nitrogen adsorption specific surface area 180m ² / g, DBP oil absorption 123cm ³ / 100g

  An O-ring was prepared in the same manner as in Example 1 except that the following “carbon black C” was used instead of “carbon black A”. Carbon black is obtained by calculating the nitrogen adsorption specific surface area and the DBP oil absorption amount according to JIS K 6217 (1997), and the values are manufacturer catalog values. The obtained O-ring was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Moreover, the image for calculating | requiring the radius of the end surface corner | angular part of the test body after a fluorine gas exposure test is shown in FIG. In FIG. 4, the black portion is a test body, and the white portion is a circle added by image processing having a corner radius.

“Carbon Black C”;
"Asahi # 70" (HAF carbon black) (Asahi Carbon Corporation)
Nitrogen adsorption specific surface area 77m ² / g, DBP oil absorption 101cm ³ / 100g

  An O-ring was prepared in the same manner as in Example 1 except that 15 parts by weight of “carbon black A” was used instead of 5 parts by weight of “carbon black A”. The obtained O-ring was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Moreover, the image for calculating | requiring the radius of the end surface corner | angular part of the test body after a fluorine gas exposure test is shown in FIG.

  An O-ring was produced in the same manner as in Example 2 except that 15 parts by weight of “carbon black B” was used instead of 5 parts by weight of “carbon black B”. The obtained O-ring was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Moreover, the image for calculating | requiring the radius of the end surface corner | angular part of the test body after a fluorine gas exposure test is shown in FIG.

  An O-ring was prepared in the same manner as in Example 3 except that 15 parts by weight of “carbon black C” was used instead of 5 parts by weight of “carbon black C”. The obtained O-ring was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Moreover, the image for calculating | requiring the radius of the end surface corner | angular part of the test body after a fluorine gas exposure test is shown in FIG. In FIG. 7, the black portion is a test body, and the white portion is a circle added by image processing having a corner radius.

Comparative Example 1
An O-ring was prepared in the same manner as in Example 1 except that the following “carbon black D” was used instead of “carbon black A”. Carbon black is obtained by calculating the nitrogen adsorption specific surface area and the DBP oil absorption amount according to JIS K 6217 (1997), and the values are manufacturer catalog values. The obtained O-ring was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Moreover, the image for calculating | requiring the radius of the end surface corner | angular part of the test body after a fluorine gas exposure test is shown in FIG. In FIG. 8, two circles are added by image processing having a corner radius.

“Carbon Black D”;
"Asahi # 50" (SRF-HS-HM carbon black) (Asahi Carbon Co., Ltd.)
Nitrogen adsorption specific surface area 23m ² / g, DBP oil absorption 63cm ³ / 100g

Comparative Example 2
An O-ring was prepared in the same manner as in Example 1 except that 15 parts by weight of “Carbon Black E” described below was used instead of 5 parts by weight of “Carbon Black A”. Carbon black is obtained by calculating the nitrogen adsorption specific surface area and the DBP oil absorption amount according to JIS K 6217 (1997), and the values are manufacturer catalog values. The obtained O-ring was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Moreover, the image for calculating | requiring the radius of the end surface corner | angular part of the test body after a fluorine gas exposure test is shown in FIG. In FIG. 9, two circles are added by image processing having a corner radius.

“Carbon Black E”;
"Thermax MT N990" (MT carbon black) (manufactured by cancarb)
Nitrogen adsorption specific surface area 10m ² / g, DBP oil absorption 43cm ³ / 100g

As is apparent from Table 1 and FIGS. 5 to 7, it is obtained from a perfluoroelastomer composition containing 15 parts by weight of carbon black having a nitrogen adsorption specific surface area of 50 m ² / g or more with respect to 100 parts by weight of the elastomer component. Even when the molded bodies of Examples 4 to 6 were exposed to a high-temperature fluorine gas atmosphere for a predetermined time, almost no dissolution phenomenon was observed. This is because carbon black with a nitrogen adsorption specific surface area of 50 m ² / g or more is an aggregate of fine particles, so it has a strong interaction with the perfluoroelastomer and can melt the elastomer even when exposed to high-temperature fluorine gas. It seems to be blocking. Further, as apparent from Table 1, FIG. 3, and FIG. 4, from a perfluoroelastomer composition containing 5 parts by weight of carbon black having a nitrogen adsorption specific surface area of 50 m ² / g or more with respect to 100 parts by weight of the elastomer component. The molded bodies of Examples 1 to 3 obtained were not observed to have a large dissolution phenomenon even when exposed to a high-temperature fluorine gas atmosphere for a predetermined time. On the other hand, the molded bodies of Comparative Examples 1 and 2 obtained from the perfluoroelastomer composition containing carbon black having a nitrogen adsorption specific surface area of 10 m ² / g or 23 m ² / g are apparent from FIGS. Thus, a large dissolution phenomenon was observed.

  Since the elastomer molded product of the present invention exhibits excellent resistance to fluorine decomposition products, it can be suitably used as a sealing material for sealing a thermal diffusion furnace of a semiconductor wafer in which fluorine decomposition products are generated.

D Diameter of the test specimen L Length of the test specimen R Radius of the corners subjected to dissolution

Claims (5)

The following perfluoroelastomer composition;
A perfluoroelastomer component, the nitrogen adsorption specific surface area of 50 m ² / g or more, 180 ^{m 2} / g or less, DBP oil absorption amount (A method) 101 cm ^3/100 g or more, those containing the following carbon black 190 cm ^3/100 g The perfluoroelastomer component comprises (a) 50 to 75 mol% tetrafluoroethylene, (b) a perfluoroalkyl vinyl ether having 1 to 5 carbon atoms in the alkyl group and / or the total number of carbons in the side chain. Is a copolymer comprising 49.8 to 25 mol% of perfluoroalkoxyalkyl vinyl ether having 3 to 11 and (c) a curing site monomer:
An elastomer molded body obtained by crosslinking and molding. The elastomer molded body according to claim 1, wherein the carbon black is acetylene black . The elastomer molded body according to claim 1 or 2 , wherein the carbon black is blended in an amount of 5 parts by weight to 30 parts by weight with respect to 100 parts by weight of the perfluoroelastomer component . It is a sealing material, The elastomer molded object of any one of Claims 1-3 characterized by the above-mentioned. The elastomer molded body according to claim 4, which is an O-ring.

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