FLUORORUBBER COMPOSITION

Abstract

A fluororubber composition that can provide a vulcanizate having excellent blister resistance, comprising 10 to 100 parts by weight of wollastonite surface-treated with a silane coupling agent and having an aspect ratio of 2 or more, and 0.5 to 10 parts by weight of a polyol-based crosslinking agent, based on 100 parts by weight of fluororubber comprising 60 to 100 wt. % of a solid fluororubber polymer and 40 to 0 wt. % of a liquid fluororubber polymer. It is preferable that 30 to 70 wt. % of wollastonite surface-treated with a silane coupling agent is replaced by wollastonite not surface-treated with a silane coupling agent, in terms of both ensuring of blister resistance and cost.

Claims

1: A fluororubber composition comprising 10 to 100 parts by weight of wollastonite surface-treated with a silane coupling agent and having an aspect ratio of 2 or more, and 0.5 to 10 parts by weight of a polyol-based crosslinking agent, based on 100 parts by weight of fluororubber comprising 60 to 100 wt. % of a solid fluororubber polymer and 40 to 0 wt. % of a liquid fluororubber polymer.

2: The fluororubber composition according to claim 1, wherein a fluororubber having a viscosity (100? C.) in the range of about 400 to 4000 cps is used as the liquid fluororubber.

3: The fluororubber composition according to claim 1, wherein the silane coupling agent is an epoxy group-containing silane coupling agent.

4: The fluororubber composition according to claim 1, wherein 30 to 70 wt. % of wollastonite surface-treated with a silane coupling agent is replaced by wollastonite not surface-treated with a silane coupling agent.

5: The fluororubber composition according to claim 1, wherein 0.1 to 10 parts by weight of a quaternary onium salt-based vulcanization accelerator is further comprised.

6: The fluororubber composition according to claim 1, wherein 0.5 to 10 parts by weight of calcium hydroxide, and 0.5 to 10 parts by weight of magnesium oxide are further comprised.

7: The fluororubber composition according to claim 1, which is used as a vulcanization molding material of a sealing material.

8: A vulcanization molded product having excellent blister resistance, which is obtained by vulcanization molding of the fluororubber composition according to claim 7.

9: The fluororubber composition according to claim 4, wherein 0.1 to 10 parts by weight of a quaternary onium salt-based vulcanization accelerator is further comprised.

10: The fluororubber composition according to claim 4, wherein 0.5 to 10 parts by weight of calcium hydroxide, and 0.5 to 10 parts by weight of magnesium oxide are further comprised.

11: The fluororubber composition according to claim 4, which is used as a vulcanization molding material of a sealing material.

12: The fluororubber composition according to claim 5, which is used as a vulcanization molding material of a sealing material.

13: The fluororubber composition according to claim 9, which is used as a vulcanization molding material of a sealing material.

14: A vulcanization molded product having excellent blister resistance, which is obtained by vulcanization molding of the fluororubber composition according to claim 11.

15: A vulcanization molded product having excellent blister resistance, which is obtained by vulcanization molding of the fluororubber composition according to claim 12.

16: A vulcanization molded product having excellent blister resistance, which is obtained by vulcanization molding of the fluororubber composition according to claim 13.

Description

EXAMPLES

[0045] The following describes the present invention with reference to Examples.

Example 1

[0046]

TABLE-US-00001 Solid fluororubber (Viton A-500, produced by 80 parts by weight DuPont) Liquid fluororubber (Daiel G-101, produced by 20 parts by weight Daikin Industries, Ltd.; viscosity (100? C.) 1200 cps) Epoxy group-containing silane coupling agent- 20 parts by weight treated wollastonite (Wollastcoat 10222 produced by NYCO; aspect ratio: 5) SRF carbon black 25 parts by weight MgO 3 parts by weight Ca(OH).sub.2 6 parts by weight Processing aid (VPA No. 2 produced by 2 parts by weight DuPontDow Elastomers) Bisphenol AF 1.5 parts by weight Quaternary phosphonium salt (Viton 1.5 parts by weight VC#20, produced by DuPont)

[0047] The above components were kneaded by any kneading means using an open roll, kneader, or the like, thereby preparing an unvulcanized fluororubber composition. For tests, the fluororubber composition was press-vulcanized at 180? C. for 8 minutes, and then maintained in an atmosphere at 230? C. for 9 hours to perform secondary vulcanization, thereby preparing a vulcanized sheet (thickness: 2 mm).

[0048] The prepared vulcanized sheet was measured and evaluated for the following items.

[0049] Hardness: according to JIS K6253 corresponding to ISO 7619-1 (Duro A, peak)

[0050] Blister resistance test: The vulcanized sheet was dipped in flon R-134a (CH.sub.2FCF.sub.3) at 40? C. for 24 hours, and then allowed to stand at 40? C. for 1 hour. The appearance of the vulcanized sheet was visually observed and evaluated as follows: no blisters (blistering) were observed: ?, blisters were observed: ?.

[0051] This evaluation satisfies blister resistance in a high temperature environment at 120? C. or more.

Example 2

[0052] In Example 1, the amount of silane coupling agent-treated wollastonite was changed to 40 parts by weight, and the amount of SRF carbon black for adjusting hardness (about 80) was changed to 15 parts by weight, respectively.

Example 3

[0053] In Example 1, the amount of silane coupling agent-treated wollastonite was changed to 60 parts by weight, and the amount of SRF carbon black for adjusting hardness (about 80) was changed to 5 parts by weight, respectively.

Example 4

[0054] In Example 1, the amount of silane coupling agent-treated wollastonite was changed to 80 parts by weight, and no SRF carbon black for adjusting hardness (about 80) was used.

Example 5

[0055] In Example 3, in which 5 parts by weight of SRF carbon black was used, the amount of silane coupling agent-treated wollastonite was changed to 20 parts by weight (33 wt. %), and 40 parts by weight (67 wt. %) of wollastonite not treated with a silane coupling agent (NYAD 400, produced by NYCO) was used.

Example 6

[0056] In Example 3, in which 5 parts by weight of SRF carbon black was used, the amount of silane coupling agent-treated wollastonite was changed to 30 parts by weight (50 wt. %), and 30 parts by weight (50 wt. %) of wollastonite (NYAD 400) was used.

Example 7

[0057] In Example 3, in which 5 parts by weight of SRF carbon black was used, the amount of silane coupling agent-treated wollastonite was changed to 40 parts by weight (67 wt. %), and 20 parts by weight (33 wt. %) of wollastonite (NYAD 400) was used.

Comparative Example 1

[0058] In Example 2, in which 15 parts by weight of SRF carbon black was used, the same amount (40 parts by weight) of wollastonite (NYAD 400) was used instead of silane coupling agent-treated wollastonite.

Comparative Example 2

[0059] In Example 3, in which 5 parts by weight of SRF carbon black was used, the same amount (60 parts by weight) of wollastonite (NYAD 400) was used instead of silane coupling agent-treated wollastonite.

Comparative Example 3

[0060] In Example 4, in which no SRF carbon black was used, the same amount (80 parts by weight) of wollastonite (NYAD 400) was used instead of silane coupling agent-treated wollastonite.

Comparative Example 4

[0061] In Example 3, in which 5 parts by weight of SRF carbon black was used, the amount of silane coupling agent-treated wollastonite was changed to 10 parts by weight (16.7 wt. %), and 50 parts by weight (83.3 wt. %) of wollastonite (NYAD 400) was used.

Comparative Example 5

[0062] In Example 4, in which no SRF carbon black was used, the amount of silane coupling agent-treated wollastonite was changed to 20 parts by weight (25 wt. %), and 60 parts by weight (75 wt. %) of wollastonite (NYAD 400) was used.

[0063] The following table shows the measurement and evaluation results in the Examples and Comparative Examples above, together with the amount of silane coupling agent-treated (Si-treated) wollastonite, the amount of wollastonite, and the amount of SRF carbon black, in the unvulcanized fluororubber compositions.

Table

[0064]

TABLE-US-00002 Example Comparative Example 1 2 3 4 5 6 7 1 2 3 4 5 [Composition: parts by weight] Si-treated 20 40 60 80 20 30 40 10 20 wollastonite Wollastonite 40 30 20 40 60 80 50 60 SRF carbon 25 15 5 0 5 5 5 15 5 0 5 0 black [measured.Math. evaluated] Hardness 80 80 80 82 79 80 79 79 80 82 80 80 Blister ? ? ? ? ? ? ? X X X X X resistance

[0065] The above results reveal the following.

[0066] (1) In Examples 1 to 4, in which wollastonite surface-treated with a silane coupling agent was used, the foaming resistance when brought into contact with flon R-134a was significantly improved.

[0067] (2) In Examples 5 to 7, in which wollastonite surface-treated with a silane coupling agent was blended with wollastonite at a ratio of 30 to 70 wt. % in the total amount of the wollastonites, the foaming resistance was significantly improved, and cost reduction could be achieved.

[0068] (3) In Comparative Examples 1 to 3, in which wollastonite not surface-treated with a silane coupling agent was used, the foaming resistance was inferior.

[0069] (4) In Comparative Examples 4 and 5, in which the ratio of wollastonite surface-treated with a silane coupling agent was less than 30 wt. %, the foaming resistance was inferior.

INDUSTRIAL APPLICABILITY

[0070] Vulcanization molded products of the fluororubber composition of the present invention can be used as, for example, sealing material used in parts to be exposed to a high temperature environment at 120? C. or more; seal parts generally used as O rings, gaskets, and packing; or other rubber parts. Examples of other rubber parts mentioned herein include oil seals, valves, and the like.

[0071] In particular, fuel consumption improvement has recently been required from the viewpoint of protecting the global environment. In order to reduce friction loss, for example, the viscosity of lubricating oil, etc., is reduced. Vulcanization molded products of the fluororubber composition of the present invention can also be effectively used as sealing materials in which blisters are not occurred even when low molecular weight components, etc., contaminated in such lubricating oil are volatilized in a high temperature environment.