SURFACE-TREATING AGENT FOR VULCANIZED RUBBER

Abstract

A surface-treating agent for vulcanized rubber, comprising, based on 100 parts by weight, as solid matters, of isocyanate group-containing 1,2-polybutadiene, an organic solvent solution containing 10 to 160 parts by weight of fluororesin particles and 2.5 to 20 parts by weight of a perfluoroalkyl group-containing oligomer-based, fluorine-containing surfactant as a dispersant. The surface-treating agent for vulcanized rubber improves the solution stability of the organic solvent solution, improves the further hardness of the entire coating film formed from the surface-treating agent, abrasion resistance, and product torque evaluation, and is effectively used as, for example, a coating agent for seal lip parts of oil seals.

Claims

1: A surface-treating agent for vulcanized rubber comprising, based on 100 parts by weight, as solid matters, of isocyanate group-containing 1,2-polybutadiene, an organic solvent solution containing 10 to 160 parts by weight of fluororesin particles and 2.5 to 20 parts by weight of a perfluoroalkyl group-containing oligomer-based, fluorine-containing surfactant as a dispersant.

2: The surface-treating agent for vulcanized rubber according to claim 1, further comprising, based on 100 parts by weight, as solid matters, of the isocyanate group-containing 1,2-polybutadiene, 100 parts by weight or less, as solid matters, of a composition solution of an OH group-containing fluororesin composition having the following formulation: [I] a copolymer of (A) a perfluoroalkylalkyl (meth)acrylate and (B) a hydroxyl group-containing (meth)acrylate, [II] a polymer of an acrylic acid alkyl ester, [III] a polymer of a fluorinated olefin, and [IV] a curing agent; and/or 60 parts by weight or less of silicone oil having a viscosity of 8,000 cs or more.

3: The surface-treating agent for vulcanized rubber according to claim 1, which is used as a coating agent for a seal lip part of an oil seal.

4: An oil seal having a seal lip part having a coating film formed from the surface-treating agent for vulcanized rubber according to claim 3.

5: An oil seal having a seal lip part having a coating film according to claim 4, which is prepared by coating the seal lip part with the surface-treating agent for vulcanized rubber, and then heat treatment at 150 to 250° C.

6: The surface-treating agent for vulcanized rubber according to claim 2, which is used as a coating agent for a seal lip part of an oil seal.

7: An oil seal having a seal lip part having a coating film formed from the surface-treating agent for vulcanized rubber according to claim 6.

8: An oil seal having a seal lip part having a coating film according to claim 7, which is prepared by coating the seal lip part with the surface-treating agent for vulcanized rubber, and then heat treatment at 150 to 250° C.

Description

EXAMPLES

[0047] The following describes the present invention with reference to Examples.

Example 1

[0048]

TABLE-US-00001 PTFE resin particles (Fluon 172J, produced by  22 parts by AGC Seimi Chemical Co., Ltd.; particle size: 0.2 weight μm) Oligomer-based, fluorine-containing surfactant  4 parts by (Surflon S-611, produced by AGC Seimi Chemical weight Co., Ltd.) NCO group-containing 1,2-polybutadiene  98 parts by (TP-1001, produced by Nippon Soda Co., Ltd.; weight a butyl acetate solution haying a solid matters content of 50 wt. %) Butyl acetate [AcOBu] 876 parts by weight
A surface-treating agent comprising the above components (total: 1000 parts by weight) was prepared, and each of the following items was measured and evaluated.

[0049] Solution stability: The surface-treating agent was prepared in a glass vessel, and the presence of precipitation was visually observed over time. [0050] (Evaluation) [0051] ◯: No sedimentation [0052] Δ: Occurred after a while [0053] X: Occurred immediately

[0054] Binder hardness: Only the binder component of the coating agent (except for the fluororesin particle component) was applied to a metal plate so that the film thickness was 50 μm, and calcined at 200° C. for 10 hours to prepare a sample. Using a dynamic ultra-micro hardness tester (produced by Shimadzu Corporation), a triangular pyramid indenter (tip angle:)115° was pressed into the sample at a load speed of 14.1 mN/sec, and the dynamic hardness when the pressing depth was 10 μm was measured. [0055] The value is preferably 10 to 30.

[0056] Friction coefficient: The coating agent was applied to the surface of fluororubber (thickness: 2 mm) molded by vulcanization compression to a film thickness of 10 μm, and calcined at 200° C. for 10 hours to prepare a sample. Using HEIDON TYPE 14DR (produced by Shinto Scientific Co., Ltd.), a steel ball (diameter: 10 mm) with a load of 50 g was pressed to the surface of the coating film, and moved for a reciprocating distance of 50 mm at a speed of 50 mm/min. Then, the dynamic friction coefficient was measured. [0057] (Evaluation) [0058] ◯: less than 0.13 [0059] Δ: 0.13 or more and less than 0.17 [0060] X: 0.17 or more

[0061] Abrasion resistance test: The coating agent was applied to the surface of fluororubber (thickness: 2 mm) molded by vulcanization compression to a film thickness of 10 μm, and calcined at 200° C. for 10 hours to prepare a sample. Using a Friction Player FPR-2000 (produced by Rhesca Co., Ltd.), an indenter ball (diameter: 3 mm) with a load of 2 kg was pressed to the surface of the coating film, and rotated with an average surface pressure of 3.9 MPa at a linear speed of 20.9 cm/sec. Then, the number of rotations until the coating film was peeled so that the rubber was exposed was measured. [0062] (Evaluation) [0063] ⊚: 150,000 rotations or more [0064] ◯: 50,000 rotations or more and less than 150,000 rotations [0065] Δ: 10,000 rotations or more and less than 50,000 rotations [0066] X: less than 10,000 rotations

[0067] Product evaluation: Torque values were measured using a rotation tester for torque measurement at a rotation frequency of 500 to 8000 rpm at an oil temperature of 80° C. [0068] (Evaluation) [0069] ◯: Torque value was lower than that of conventional product [0070] Δ: Torque value was equivalent to that of conventional product [0071] X: Torque value was higher than that of conventional product

Example 2

[0072] In Example 1, the amount of the NCO group-containing 1,2-polybutadiene was changed to 77 parts by weight, the amount of butyl acetate was changed to 868 parts by weight, respectively, and 29 parts by weight of an OH group-containing fluororesin composition solution (Defensa TR-103, produced by DIC Corporation; OH value: 4.1 mgKOH/g solution, a MEK-AcOBu-MEK mixed solvent solution having a solid matters content of 30 wt. %) was further used.

Example 3

[0073] In Example 1, the amount of the PTFE resin particles was changed to 21 parts by weight, the amount of the NCO group-containing 1,2-polybutadiene was changed to 90 parts by weight, the amount of butyl acetate was changed to 878 parts by weight, respectively, and 8 parts by weight of silicone oil (KF-96H-1,000,000 cs, produced by Shin-Etsu Chemical Co., Ltd.) was further used.

Example 4

[0074]

TABLE-US-00002 PTFE resin particles (Fluon 172J)  37 parts by weight Fluorine-containing surfactant (Surflon S-611)  4 parts by weight NCO group-containing 1,2-polybutadiene (TP-1001)  74 parts by weight Butyl acetate 885 parts by weight
A surface-treating agent comprising the above components was prepared, and the same measurement and evaluation as in Example 1 were performed.

Example 5

[0075] In Example 4, the amount of the NCO group-containing 1,2-polybutadiene was changed to 59 parts by weight, the amount of butyl acetate was changed to 879 parts by weight, respectively, and 22 parts by weight of an OH group-containing fluororesin composition solution (Defensa TR-103) was further used.

Example 6

[0076] In Example 4, the amount of the PTFE resin particles was changed to 34 parts by weight, the amount of the NCO group-containing 1,2-polybutadiene was changed to 68 parts by weight, the amount of butyl acetate was changed to 886 parts by weight, respectively, and 8 parts by weight of silicone oil (KF-96H-1,000,000 cs) was further used.

Example 7

[0077] In Example 1, the same amount (4 parts by weight) of F-561 (produced by DIC Corporation) was used as an oligomer-based, fluorine-containing surfactant.

Comparative Example 1

[0078] In Example 1, the same amount (4 parts by weight) of Surflon S-243 (ethyleneoxide addition type, produced by AGC Seimi Chemical Co., Ltd.) was used as a fluorine-containing surfactant.

Comparative Example 2

[0079] In Example 1, the same amount (4 parts by weight) of F-444 (ethyleneoxide addition type, produced by DICCorporation) was used as a fluorine-containing surfactant.

Comparative Example 3

[0080] In Example 1, the amount of the butyl acetate was changed to 880 parts by weight, and oligomer-based, fluorine-containing surfactant was not used.

Comparative Example 4

[0081] In Example 1, the amount of the fluorine-containing surfactant was changed to 1 part by weight, and the amount of butyl acetate was changed to 879 parts by weight, respectively.

Comparative Example 5

[0082]

TABLE-US-00003 Fluororesin particle solution 365 parts by weight (a butyl acetate solution having a solid matters content of 5 wt. %) PE wax solution 365 parts by weight (a butyl acetate solution having a solid matters content of 5 wt. %) OH group-containing fluororesin composition  40 parts by weight solution (Defensa TR-103) Urethane resin solution  40 parts by weight (16-416, produced by DIC Corporation; a MEK- IPA mixed solvent solution having a solid matters content of 30 wt. %) Isopropanol [IPA]  95 parts by weight Methyl ethyl ketone [MEK]  95 parts by weight

[0083] A surface-treating agent comprising the above components was prepared, and the same measurement and evaluation as in Example 1 were performed.

Comparative Example 6

[0084]

TABLE-US-00004 Fluororesin particle solution 468 parts by weight (a butyl acetate solution haying a solid matters content of 5 wt. %) PE wax solution 468 parts by weight (a butyl acetate solution haying a solid matters content of 5 wt. %) NCO group-containing 1,2-polybutadiene (TP-  54 parts by weight 1001) OH group-containing fluororesin composition  10 parts by weight solution (Defensa TR-103)
A surface-treating agent comprising the above components was prepared, and the same measurement and evaluation as in Example 1 were performed.

Comparative Example 7

[0085] In Comparative Example 6, the amount of the NCO group-containing 1,2-polybutadiene was changed to 56 parts by weight, and 8 parts by weight of silicone oil (KF-96H-1,000,000 cs) was further used, and the OH group-containing fluororesin composition solution was not used.

Comparative Example 8

[0086] In Comparative Example 6, the amount of the fluororesin particle solution and the amount of the PE wax solution were both changed to 470 parts by weight, the amount of the NCO group-containing 1,2-polybutadiene was changed to 60 parts by weight, respectively, and the OH group-containing fluororesin composition solution was not used.

[0087] The following table shows the measurement results obtained in the above Examples and Comparative Examples.

TABLE-US-00005 TABLE Abrasion resistance Friction Measurement Product coefficient value torque Solution Binder Measurement Evalu- (× 10.sup.4 Evalu- Evalu- Example stability hardness value ation times) ation ation Ex. 1 ◯ 17.9 0.11 ◯ 3 Δ ◯ Ex. 2 ◯ 15.9 0.10 ◯ 8 ◯ ◯ Ex. 3 ◯ 14.7 0.08 ◯ 9 ◯ ◯ Ex. 4 ◯ 17.9 0.09 ◯ 5 Δ ◯ Ex. 5 ◯ 15.9 0.07 ◯ 8 ◯ ◯ Ex. 6 ◯ 14.7 0.05 ◯ 9 ◯ ◯ Ex. 7 ◯ 18.5 0.12 ◯ 3 Δ ◯ Comp. X 18.9 0.10 ◯ 2 Δ ◯ Ex. 1 Comp. X 19.0 0.10 ◯ 3 Δ ◯ Ex. 2 Comp. X 26.4 0.11 ◯ 5 Δ ◯ Ex. 3 Comp. Δ 21.5 0.11 ◯ 5 Δ ◯ Ex. 4 Comp. ◯ 1.1 0.10 ◯ 0.3 X X Ex. 5 Comp. ◯ 6.7 0.12 ◯ 30 ⊚ Δ Ex. 6 Comp. ◯ 6.2 0.09 ◯ 20 ⊚ Δ Ex. 7 Comp. ◯ 7.6 0.15 Δ 3 Δ Δ Ex. 8