Uncrosslinked rubber composition and rubber molded product using the same

Abstract

This uncrosslinked rubber composition comprises: a base rubber containing a silicone rubber as the main component; a compound that has a perfluoro backbone having an ethylenically unsaturated bond; and a first silica. The mass ratio of the contained amount of the compound having the perfluoro backbone to the contained amount of the first silica is less than 5.

Description

[Technical Field]

[0001] The present invention relates to an uncrosslinked rubber composition and a rubber molded article using the same. [Background technology]

[0002] Silicone rubber compositions are used in many applications due to their excellent electrical insulation properties, heat resistance, cold resistance, etc. For example, Patent Document 1 discloses that a rubber composition obtained by mixing a silicone rubber composition with a perfluoropolyether-based fluorine-containing rubber composition is used for sealing materials, etc. Patent Document 2 discloses that a silicone rubber composition containing an alkenyl group-containing organopolysiloxane, an alkenyl group-containing perfluoropolyether, and an organohydropolysiloxane is used for automotive rubber parts, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5083489 [Patent Document 2] Japanese Patent Application Publication No. 11-5902 Summary of the Invention

[0004] The present invention provides a rubber composition comprising a base rubber mainly composed of silicone rubber, a compound having a perfluoro skeleton with an ethylenically unsaturated bond, a first silica, and an organic peroxide, wherein the silicone rubber Rubber compound with secondary silica dispersed in rubber An uncrosslinked rubber composition prepared using the perfluoro skeleton compound is a compound having a perfluoropolyether structure, The content of the perfluoro skeleton compound is 3 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the rubber compound, and the mass ratio of the content of the perfluoro skeleton compound to the content of the first silica is less than 5.

[0005] The present invention is a molded rubber article formed by molding the uncrosslinked rubber composition of the present invention into a predetermined shape and crosslinking it. DETAILED DESCRIPTION OF THE INVENTION

[0006] The embodiments will be described in detail below.

[0007] The uncrosslinked rubber composition according to the embodiment contains a base rubber A mainly composed of silicone rubber, a compound B having a perfluoro skeleton with an ethylenically unsaturated bond, and a first silica C. The mass ratio of the content of the compound B having a perfluoro skeleton to the content of the first silica C in the uncrosslinked rubber composition is less than 5.

[0008] According to the uncrosslinked rubber composition according to this embodiment, a rubber molded article having excellent plasma resistance can be obtained.

[0009] Here, the "first silica" in the present application refers to silica that is blended with base rubber A together with perfluoro-skeleton compound B to form an uncrosslinked rubber composition. The "second silica" described below refers to silica that is blended in advance with silicone rubber to form rubber compound X.

[0010] The base rubber A is mainly composed of silicone rubber. Therefore, the content of silicone rubber in the base rubber A is more than 50% by mass, and from the viewpoint of obtaining a rubber molded product with excellent plasma resistance, it is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass. In addition to silicone rubber, the base rubber A may also contain, for example, fluororubber.

[0011] Examples of silicone rubbers include millable types such as phenylvinylmethylsilicone rubber (PVMQ), vinylmethylsilicone rubber (VMQ), fluorosilicone rubber (FVMQ), dimethylsilicone rubber (MQ), etc. The silicone rubber preferably contains one or more of these, and more preferably contains phenylvinylmethylsilicone rubber (PVMQ) from the viewpoint of obtaining a rubber molded product with excellent plasma resistance and low-temperature flexibility.

[0012] The uncrosslinked rubber composition according to the embodiment may be prepared using a rubber compound X, which is formed by blending a second silica into the silicone rubber described above. In the rubber compound X, the second silica is dispersed in the silicone rubber. Examples of the second silica include dry process silica and wet process silica. The content of the second silica in the rubber compound X is, for example, 20% by mass or more and 40% by mass or less. An example of a commercially available material for the rubber compound X is KE-186-U manufactured by Shin-Etsu Chemical Co., Ltd.

[0013] The perfluoro-skeleton compound B is uniformly mixed with the base rubber A. Examples of the perfluoro-skeleton compound B include a compound having a perfluoropolyether structure and a compound having a perfluoroalkylene structure. From the viewpoint of obtaining a rubber molded product having excellent plasma resistance, it is preferable that the perfluoro-skeleton compound B contains a compound having a perfluoropolyether structure.

[0014] Examples of the functional group containing an ethylenically unsaturated bond contained in the perfluoro-skeleton compound B include a vinyl group, an allyl group, a propargyl group, a butenyl group, and an ethynyl group. From the viewpoint of obtaining a rubber molded article having excellent plasma resistance, the functional group containing an ethylenically unsaturated bond is preferably a vinyl group. From the same viewpoint, the perfluoro-skeleton compound B preferably contains two or more functional groups having an ethylenically unsaturated bond.

[0015] From the viewpoint of obtaining a rubber molded product with excellent plasma resistance, the perfluoro-skeleton compound B preferably contains a one-component material, and more preferably contains one having a viscosity at 23°C of 350 Pa·s or more and 450 Pa·s or less.

[0016] An example of a commercially available material of perfluoro-skeleton compound B is the SIFEL3000 series manufactured by Shin-Etsu Chemical Co., Ltd. From the viewpoint of obtaining a rubber molded product with excellent plasma resistance, the commercially available material of perfluoro-skeleton compound B preferably includes a one-component material from the SIFEL3000 series, more preferably one having a viscosity at 23°C of 350 Pa s or more and 450 Pa s or less, and even more preferably X-71-369-N.

[0017] When a rubber compound X composed of a silicone rubber and a second silica is used, the content of the perfluoro-skeleton compound B in the uncrosslinked rubber composition according to the embodiment is preferably 3 parts by mass or more and 40 parts by mass or less, more preferably 5 parts by mass or more and 30 parts by mass or less, and even more preferably 10 parts by mass or more and 25 parts by mass or less, per 100 parts by mass of the rubber compound X, from the viewpoint of obtaining a rubber molded product having excellent plasma resistance.

[0018] The first silica C is dispersed in a uniformly mixed base rubber A and perfluoro-skeleton compound B. Examples of the first silica C include dry process silica and wet process silica. Examples of the dry process silica include fumed silica. Examples of the wet process silica include precipitated silica and gel process silica. From the viewpoint of obtaining a rubber molded product with excellent plasma resistance, the first silica C preferably contains dry process silica, and more preferably contains fumed silica.

[0019] The first silica C may contain hydrophilic silica that has not been surface-treated. From the viewpoint of obtaining a rubber molded product having excellent plasma resistance, the primary particle diameter of the hydrophilic silica is preferably 5 nm or more and 20 nm or less, more preferably 10 nm or more and 15 nm or less. From the same viewpoint, the BET specific surface area of ​​the hydrophilic silica is, for example, 150 m 2 / g or more 200m 2 / g or less, 175m 2 / g or more 225m 2 / g or less.

[0020] The first silica C may contain hydrophobic silica that has been surface-treated with a surface treatment agent. Examples of surface treatment agents include dimethyldichlorosilane, hexamethyldisilazane, octylsilane, and silicone oil. From the viewpoint of obtaining a rubber molded product with excellent plasma resistance, it is preferable that the hydrophobic silica contains one that has been surface-treated with dimethyldichlorosilane. From the same viewpoint, the primary particle diameter of the hydrophobic silica is preferably 10 nm or more and 25 nm or less, more preferably 15 nm or more and 20 nm or less. From the same viewpoint, the BET specific surface area of ​​the hydrophobic silica is, for example, 50 m 2 / g or more 150m 2 / g or less, 90m 2 / g or more 130m 2 / g or less.

[0021] When a rubber compound X composed of a silicone rubber and a second silica is used, the content of the first silica C in the uncrosslinked rubber composition according to the embodiment is preferably 2 to 25 parts by mass, more preferably 3 to 15 parts by mass, and even more preferably 4 to 10 parts by mass, per 100 parts by mass of rubber compound X, from the viewpoint of obtaining a rubber molded product with excellent plasma resistance.

[0022] In the uncrosslinked rubber composition according to the embodiment, the mass ratio of the content of the perfluoro-skeleton compound B to the content of the first silica C is preferably 1.5 or more and 4.5 or less, more preferably 2 or more and 4 or less, from the viewpoint of obtaining a rubber molded product having excellent plasma resistance.

[0023] The uncrosslinked rubber composition according to the embodiment may further contain an organic peroxide D as a thermal crosslinking agent. Examples of the organic peroxide D include dialkyl peroxides, peroxyketals, and peroxyesters. Examples of the dialkyl peroxides include 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, dicumyl peroxide, and 1,3-di(t-butylperoxy)diisopropylbenzene. Examples of the peroxyketals include 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)cyclohexane, and n-butyl-4,4-di(t-butylperoxy)valerate. Examples of the peroxyesters include 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-hexylperoxybenzoate, and t-butylperoxybenzoate. The organic peroxide D preferably contains one or more of these, and from the viewpoint of obtaining a rubber molded product with excellent plasma resistance, it preferably contains a dialkyl peroxide, and more preferably contains 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane.

[0024] When a rubber compound X composed of silicone rubber and a second silica is used, the content of the organic peroxide D as a thermal crosslinking agent in the uncrosslinked rubber composition according to the embodiment is preferably 0.5 parts by mass or more and 5 parts by mass or less, more preferably 1 part by mass or more and 3 parts by mass or less, per 100 parts by mass of rubber compound X, from the viewpoint of obtaining a rubber molded product having excellent plasma resistance.

[0025] The uncrosslinked rubber composition according to the embodiment may contain rubber compounding agents such as plasticizers, processing aids, and antioxidants, but preferably does not contain carbon black from the viewpoint of controlling dust generation when exposed to a plasma atmosphere.

[0026] The uncrosslinked rubber composition according to the embodiment can be prepared by kneading a base rubber A containing silicone rubber as a main component, a perfluoro-skeleton compound B, a first silica C, and other rubber compounding ingredients using a known rubber kneading machine such as a Banbury mixer, a kneader, an open roll, etc. At this time, a rubber compound X composed of silicone rubber and a second silica may be used.

[0027] The uncrosslinked rubber composition according to the embodiment can be molded into a predetermined shape and crosslinked to form a molded rubber product of the rubber composition. In this case, the crosslinking of the uncrosslinked rubber composition may be performed only by primary crosslinking, in which the uncrosslinked rubber composition is heated and pressurized, for example, by press molding. Alternatively, secondary crosslinking, in which the primary crosslinked product is heated at a higher temperature for a longer period of time, for example, by using a gear oven, may be combined. Furthermore, radiation crosslinking, in which the secondary crosslinked product is irradiated with radiation, may be combined.

[0028] Examples of rubber molded products include sealing materials such as O-rings, etc. From the viewpoint of obtaining excellent plasma resistance, rubber molded products are suitable as sealing materials for semiconductor manufacturing equipment.

[0029] The hardness Hs of the rubber composition forming the rubber molded product is preferably A50 or more and A90 or less, more preferably A60 or more and A80 or less, and even more preferably A70 or more and A80 or less. This hardness Hs is measured based on JIS K6253-3:2012 using a type A durometer as the instantaneous value when a pressure plate is brought into contact with a test piece.

[0030] The tensile strength Tb of the rubber composition forming the molded rubber product is preferably 7 MPa or more, more preferably 8 MPa or more. The elongation Eb is preferably 150% or more, more preferably 250% or more. The tensile stress S100 at 100% elongation is preferably 1.5 MPa or more and 4 MPa or less, more preferably 2 MPa or more and 2.5 MPa or less. The tensile strength Tb, elongation Eb, and tensile stress S100 at 100% elongation are measured using a dumbbell-shaped No. 3 test piece in accordance with JIS K6251:2017. [Example]

[0031] (Uncrosslinked rubber composition) The following uncrosslinked rubber compositions were prepared in Examples 1 to 11 and Comparative Examples 1 to 7. The respective compositions are also shown in Tables 1 and 2.

[0032] Example 1 The rubber compound X (KE-186-U, manufactured by Shin-Etsu Chemical Co., Ltd.) was composed of base rubber A, phenyl vinyl methyl silicone rubber (PVMQ-X), and second silica. 100 parts by mass of this rubber compound X was mixed with 5 parts by mass of perfluoro-skeleton compound B, a perfluoropolyether structure compound (X-71-369-N, manufactured by Shin-Etsu Chemical Co., Ltd., one-component material, viscosity (23°C): 410 Pa s), and first silica C, a hydrophilic silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd., surface-untreated dry-process silica, primary particle size: 12 nm, BET specific surface area: 200 m). 2 An uncrosslinked rubber composition was prepared by blending and kneading 3 parts by mass of 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (C-8, manufactured by Shin-Etsu Chemical Co., Ltd.) as organic peroxide D, and the resulting mixture was designated Example 1.

[0033] <Example 2> An uncrosslinked rubber composition was prepared in the same manner as in Example 1, except that the amount of hydrophilic silica in the first silica C was 5 parts by mass per 100 parts by mass of the rubber compound X. This was designated Example 2.

[0034] Example 3 An uncrosslinked rubber composition having the same composition as in Example 2 was prepared, except that the compounding amount of the perfluoropolyether structure compound B of the perfluoro skeleton compound was 10 parts by mass per 100 parts by mass of the rubber compound X, and this was designated as Example 3.

[0035] Example 4 An uncrosslinked rubber composition having the same composition as in Example 2 was prepared, and designated Example 4, except that the compounding amount of the perfluoropolyether structure compound B of the perfluoro skeleton compound was 20 parts by mass per 100 parts by mass of the rubber compound X.

[0036] <Example 5> An uncrosslinked rubber composition having the same constitution as in Example 4 was prepared, and designated Example 5, except that the amount of hydrophilic silica in the first silica C was 8 parts by mass per 100 parts by mass of the rubber compound X.

[0037] Example 6 An uncrosslinked rubber composition having the same composition as in Example 4 was prepared, and designated Example 6, except that the amount of hydrophilic silica in the first silica C was 15 parts by mass per 100 parts by mass of the rubber compound X.

[0038] Example 7 As the first silica C, instead of hydrophilic silica, hydrophobic silica (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd., dry-process silica surface-treated with dimethyldichlorosilane, primary particle diameter: 16 nm, BET specific surface area: 130 m) was used. 2 An uncrosslinked rubber composition having the same constitution as in Example 2 except that 1 / g of hydroxypropyl methylcellulose was blended was prepared and designated Example 7.

[0039] Example 8 An uncrosslinked rubber composition having the same composition as in Example 7 was prepared, except that the compounding amount of the perfluoropolyether structure compound B of the perfluoro skeleton compound was 10 parts by mass per 100 parts by mass of the rubber compound X, and this was designated as Example 8.

[0040] Example 9 An uncrosslinked rubber composition having the same composition as in Example 7 was prepared, except that the compounding amount of the perfluoropolyether structure compound B of the perfluoro skeleton compound was 20 parts by mass per 100 parts by mass of the rubber compound X, and this was designated as Example 9.

[0041] Example 10 An uncrosslinked rubber composition having the same composition as in Example 2 was prepared, except that rubber compound Y (KE-183-U manufactured by Shin-Etsu Chemical Co., Ltd.), which was composed of phenyl vinyl methyl silicone rubber (PVMQ-Y) of base rubber A and second silica, was used instead of rubber compound X, and this was designated Example 10.

[0042] Example 11 An uncrosslinked rubber composition having the same composition as Example 10 was prepared, except that the compounding amount of the perfluoropolyether structure compound B of the perfluoro skeleton compound was 20 parts by mass per 100 parts by mass of rubber compound Y, and this was designated Example 11.

[0043] <Comparative Example 1> An uncrosslinked rubber composition was prepared as Comparative Example 1, which had the same constitution as Examples 1 to 9 except that the perfluoro-skeleton compound B and the first silica C were not blended.

[0044] <Comparative Example 2> An uncrosslinked rubber composition was prepared with the same composition as Comparative Example 1, except that 5 parts by mass of carbon black (Thermax N990, manufactured by Cancarb) was blended with 100 parts by mass of rubber compound X, and designated Comparative Example 2.

[0045] <Comparative Example 3> An uncrosslinked rubber composition having the same composition as Comparative Example 2 was prepared, and designated Comparative Example 3, except that 5 parts by mass of a perfluoropolyether structure compound (perfluoro skeleton compound B) was blended with 100 parts by mass of rubber compound X.

[0046] <Comparative Example 4> An uncrosslinked rubber composition having the same constitution as Comparative Example 3 was prepared, except that the compounding amount of the perfluoropolyether structure compound B of the perfluoro skeleton compound was 10 parts by mass per 100 parts by mass of the rubber compound X, and this was designated Comparative Example 4.

[0047] <Comparative Example 5> An uncrosslinked rubber composition having the same composition as Comparative Example 3 was prepared, and designated Comparative Example 5, except that the compounding amount of the perfluoropolyether structure compound B of the perfluoro skeleton compound was 20 parts by mass per 100 parts by mass of the rubber compound X.

[0048] <Comparative Example 6> An uncrosslinked rubber composition having the same constitution as in Example 2 was prepared, and designated Comparative Example 6, except that the amount of hydrophilic silica in the first silica C was 1 part by mass per 100 parts by mass of the rubber compound X.

[0049] <Comparative Example 7> An uncrosslinked rubber composition having the same constitution as that of Example 10 except that Compound B having a perfluoro skeleton was not blended was prepared and designated Comparative Example 7.

[0050] [Table 1]

[0051] [Table 2]

[0052] (Test method and results) The uncrosslinked rubber composition was crosslinked to prepare test pieces of the rubber composition, and the following tests were carried out using the test pieces. The results are shown in Tables 1 and 2.

[0053] <Hardness> The uncrosslinked rubber compositions of Examples 1 to 11 and Comparative Examples 1 to 7 were each subjected to primary crosslinking and secondary crosslinking to prepare a 2 mm thick sheet-like rubber composition. The primary crosslinking conditions were press molding at 165°C for 5 minutes, and secondary crosslinking conditions were using a gear oven at 200°C for 4 hours (the same applies below). Three sheets of the sheet-like rubber composition were then stacked to form a test piece, and the hardness Hs was measured using a Type A durometer in accordance with JIS K6253-3:2023 as the instantaneous value when a pressure plate was brought into contact with the test piece.

[0054] <Tensile properties> The uncrosslinked rubber compositions of Examples 1 to 11 and Comparative Examples 1 to 7 were each subjected to primary crosslinking and secondary crosslinking to prepare dumbbell-shaped No. 3 test pieces of the rubber compositions. Using the test pieces, the tensile strength Tb, elongation Eb, and tensile stress S100 at 100% elongation were measured in accordance with JIS K6251:2017.

[0055] <Plasma resistance> The uncrosslinked rubber compositions of Examples 1 to 11 and Comparative Examples 1 to 7 were subjected to primary and secondary crosslinking to prepare AS-214 O-ring test pieces. The test pieces were then placed in a plasma exposure device (manufactured by Shinko Seiki Co., Ltd.) and exposed to plasma generated for 30 minutes using a 2:1 volumetric mixture of O2 gas and CF4 gas at a frequency of 2.45 GHz, a pressure of 100 Pa, an output of 1500 W, and a total gas flow rate of 510 ml / min. The presence or absence of dust generation was visually confirmed. The mass loss rate and mass loss ratio were calculated using the following formula. A mass loss ratio of less than 1.1 was rated as A, and a mass loss ratio of 1.1 or greater was rated as B. An AS-214 O-ring made of a ternary FKM was used as the standard test piece. This standard test piece was also subjected to plasma exposure under the same conditions as above, and the mass loss rate was calculated.

[0056] Mass loss rate (%) = (difference in mass of test piece before and after exposure / mass of test piece before exposure) x 100 Mass reduction ratio = mass reduction rate / mass reduction rate of standard specimen [Industrial Applicability]

[0057] The present invention is useful in the technical fields of uncrosslinked rubber compositions and rubber molded articles using the same.

Claims

1. An uncrosslinked rubber composition prepared using a rubber compound containing a base rubber mainly composed of silicone rubber, a perfluoro-skeleton compound having an ethylenically unsaturated bond, a first silica, and an organic peroxide, in which a second silica is dispersed in the silicone rubber, the perfluoro skeleton compound is a compound having a perfluoropolyether structure, the content of the perfluoro skeleton compound is 3 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the rubber compound, an uncrosslinked rubber composition in which the mass ratio of the content of the perfluoro skeleton compound to the content of the first silica is less than 5;

2. The uncrosslinked rubber composition according to claim 1, The uncrosslinked rubber composition wherein the base rubber comprises a phenyl vinyl methyl silicone rubber.

3. The uncrosslinked rubber composition according to claim 1, The uncrosslinked rubber composition, wherein the first silica comprises dry-process silica.

4. The uncrosslinked rubber composition according to claim 1, The uncrosslinked rubber composition has a content of the first silica of 2 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the rubber compound.

5. The uncrosslinked rubber composition according to claim 1, The uncrosslinked rubber composition, wherein the organic peroxide contains a dialkyl peroxide.

6. The uncrosslinked rubber composition according to claim 1, An uncrosslinked rubber composition, wherein the content of the second silica in the rubber compound is 20% by mass or more and 40% by mass or less.

7. A rubber molded article formed by molding the uncrosslinked rubber composition according to claim 1 into a predetermined shape and crosslinking it.

8. The rubber molded product according to claim 7, The rubber molded product is a sealing material.

9. The rubber molded product according to claim 8, The rubber molded product, wherein the sealing material is a sealing material for semiconductor manufacturing equipment.

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