Acrylic rubber composition

Abstract

An acrylic rubber composition comprising 0.05 to 3.0 parts by weight of a fluorine-containing compound having a melting point of 30 to 100° C., based on 100 parts by weight of acrylic rubber. The acrylic rubber composition that can improve the dispersibility of a processing aid in the compound and the rubber compound handling properties during open roll operation without using a silicone-based processing aid, which causes bleeding of vulcanizates, and that satisfies the various characteristics, such as dimensional stability and heat resistance, of vulcanizates.

Claims

1. An acrylic rubber composition comprising 0.05 to 3.0 parts by weight of a fluorine-containing compound processing aids having a melting point of 30 to 100° C., based on 100 parts by weight of acrylic rubber.

2. The acrylic rubber composition according to claim 1, wherein the acrylic rubber is an amine vulcanizable group-containing acrylic rubber.

3. The acrylic rubber composition according to claim 2, wherein the amine vulcanizable group-containing acrylic rubber is carboxyl group-containing acrylic rubber, epoxy group-containing acrylic rubber, or chlorine group-containing acrylic rubber.

4. The acrylic rubber composition according to claim 1, wherein the fluorine-containing compound is the compound represented by the general formula:
RfO(CF.sub.2O).sub.p(C.sub.2F.sub.4O).sub.q(C.sub.3F.sub.6O).sub.rRf wherein Rf is a perfluoro lower alkyl group having 1 to 5 carbon atoms, p, q and r are individually a positive integer or 0, and p+q+r is not 0.

5. The acrylic rubber composition according to claim 1, wherein other processing aids is further comprised at a ratio of about 1.5 parts by weight or less.

6. A vulcanization molded product of the acrylic rubber composition according to claim 1.

7. The vulcanization molded product according to claim 6, which is used as a sealing material.

8. A vulcanization molded product of the acrylic rubber composition according to claim 2.

9. A vulcanization molded product of the acrylic rubber composition according to claim 4.

10. A vulcanization molded product of the acrylic rubber composition according to claim 5.

Description

EXAMPLES

(1) The following describes the present disclosure with reference to Examples.

Example 1

(2) TABLE-US-00001 Carboxyl group-containing acrylic rubber  100 parts by (Noxtite PA-522, produced by Unimatec Co., Ltd.) weight Carbon black (Seast G-SO, produced by   50 parts by Tokai Carbon Co., Ltd.) weight Dispersion aid (Stearic Acid TST, produced by  1.5 parts by Miyoshi Oil & Fat Co., Ltd.) weight Antioxidant (Nocrac CD, produced by Ouchi  2.0 parts by Shinko Chemical Industrial Co., Ltd.) weight Vulcanization accelerator  2.0 parts by (Nocceler DT, produced by Ouchi weight Shinko Chemical Industrial Co., Ltd.) 4,4-Diaminodiphenyl ether (produced by Tokyo 1.0 part by Chemical Industry Co., Ltd.) weight Fluorine-based compound being a processing aid  2.0 parts by (FB962, produced by Daikin Industries, Ltd., weight melting point: about 40° C.)
The above components other than the processing aid were kneaded using a 1 L kneader and an open roll at 110° C. or lower for 10 to 30 minutes, and the processing aid was then added using an open roll, thereby producing an unvulcanized rubber sheet.

(3) The unvulcanized rubber sheet was compressed at a constant pressure using a press molding machine at 180° C. for 8 minutes to perform vulcanization molding (primary vulcanization) of a slab test piece and an O-ring for fixing (bearing number G25-shaped) described in JIS B 2401-1, and the compression set of the O-ring was measured. Further, the slab test piece and the sample after compression set measurement were subjected to post curing at 175° C. for 15 hours, and the following items were measured and evaluated. As a result, all the items were evaluated as “good”.

(4) Roll processability: After the components other than the processing aid were kneaded with a kneader and then kneaded through a 12-inch open roll with a gap of 3 mm, the processing aid was added to prepare a compound. In the operation of removing the compound from the roll surface by turning back with a roll knife and kneading the compound, the roll processability was evaluated in the following manner. Those that could be turned back were evaluated as “good”, and those that were sticky and could not be turned back were evaluated as “bad”.

(5) Dimensional stability: The volume change rate (%) before and after secondary vulcanization at 175° C. for 15 hours was calculated according to the sample shape and method of JIS K6258 (2016) corresponding to ISO 1817 (2015), and the volume change rate in the formulation without a processing aid was subtracted from this value. A value of less than 0.5% was evaluated as “good” and a value of 0.5% or more was evaluated as “bad”.

(6) Dispersibility: The surface of the slab test piece after secondary vulcanization was visually observed. When a smooth surface was confirmed, the dispersion was evaluated as “good”. When fine irregularities were confirmed due to the melting point or compatibility of the processing aid, vulcanization inhibition, etc., or when swelling was confirmed, the dispersion was evaluated as “bad”.

(7) Bleeding properties: The slab test piece after secondary vulcanization was allowed to stand at room temperature for 24 hours, and the surface was visually observed before and after wiping with a Kimwipe. When no trace of wiping was confirmed, there was no bleeding, which was evaluated as “good”. When a trace of wiping was confirmed, there was bleeding, which was evaluated as “bad”.

(8) Compression set: According to JIS B2401-1 (2012) corresponding to ISO 3601-1 (2008), a semi-circular sample with a thickness of about 3.1 mm obtained by cutting the G25-shaped O-ring at two points was sandwiched between SUS plates, and placed in an oven at 150° C. while being compressed by 25%. The sample was taken out after 70 hours, and immediately after that, the sample was released from the SUS plates and left at room temperature for 30 minutes. The compression set value (%) was calculated from the change in thickness of outer diameter before and after the test according to JIS K6262 (2013) corresponding to ISO 815-1 (2008) and ISO 815-2 (2008). A value obtained by subtracting the compression set value in the formulation without a processing aid of +2% or less was evaluated as “good”, and a value of greater than 2% was evaluated as “bad”.

Example 2

(9) In Example 1, the amount of fluorine-containing compound which was a processing aid, was changed to 0.5 parts by weight, all the items were evaluated as “good”.

Example 3

(10) In Example 1, the same amount (2.0 parts by weight) of TECNOFLON FPA 1, produced by Solvay (melting point: 58° C. or less) was used as the fluorine-containing compound which was a processing aid, all the items were evaluated as “good”.

Example 4

(11) In Example 3, the amount of fluorine-containing compound which was a processing aid, was changed to 0.5 parts by weight, all the items were evaluated as “good”.

Example 5

(12) In Example 3, the amount of fluorine-containing compound which was a processing aid, was changed to 0.2 parts by weight, all the items were evaluated as “good”.

Example 6

(13) In Example 1, 1.0 part by weight of TECNOFLON FPA1 was used as the fluorine-containing compound, which was a processing aid, and further 0.5 parts by weight of a fatty acid monoamide (O-200, produced by Nihon Kasei Co., Ltd.; melting point: 73 to 75° C.) was used, all the items were evaluated as “good”.

Comparative Example 1

(14) In Example 1, the no processing aid was used, the dispersibility and bleeding properties were evaluated as “good,” whereas the roll processability was evaluated as “bad”. The volume change rate indicating dimensional stability was −3.50%, and the compression set value was 15.

Comparative Example 2

(15) In Example 1, the same amount (2.0 parts by weight) of silicone (WS280, produced by SCHILL & SEILACHER; liquid at room temperature) was used as the processing aid, the bleeding properties was evaluated as “bad”, and the other items were evaluated as “good”.

Comparative Example 3

(16) In Example 1, the same amount (2.0 parts by weight) of a fatty acid ester (VPA#2, produced by Chemours; melting point: 76 to 82° C.) was used as the processing aid, the bleeding properties and compression set were evaluated as “bad” and the other items were evaluated as “good”.

Comparative Example 4

(17) In Example 3, the amount of fatty acid ester (VPA#2), which was a processing aid, was changed to 0.5 parts by weight, the roll processability was evaluated as “bad” and the other items were evaluated as “good”.

Comparative Example 5

(18) In Example 1, the same amount (2.0 parts by weight) of a fatty acid ester (Deoflow 821, produced by D.O.G Chemie; melting point: about 60 to 70° C.), which was a processing aid, was used, the bleeding properties was evaluated as “bad” and the other items were evaluated as “good”.

Comparative Example 6

(19) In Example 1, the same amount (2.0 parts by weight) of a fatty acid sodium salt (NS-Soap, produced by Kao Corporation) was used as the processing aid, the dispersibility and compression set were evaluated as “bad” and the other items were evaluated as “good”.

Comparative Example 7

(20) In Example 1, the same amount (2.0 parts by weight) of a fatty acid monoamide (O-200, produced by Nihon Kasei Co., Ltd.; melting point: 73 to 75° C.) was used as the processing aid, the dimensional stability and compression set were evaluated as “bad” and the other items were evaluated as “good”.

Comparative Example 8

(21) In Example 1, the same amount (2.0 parts by weight) of a fatty acid bisamide (L, produced by Nihon Kasei Co., Ltd.; melting point: 156 to 160° C.) was used as the processing aid, the bleeding properties was evaluated as “bad” and the other items were evaluated as “good”.

Comparative Example 9

(22) In Example 1, the same amount (2.0 parts by weight) of an aliphatic amine (HT290, produced by SCHILL & SEILACHER; melting point: about 85° C.) was used as the processing aid, the dimensional stability, dispersibility and compression set were evaluated as “bad” and the other items were evaluated as “good”.

Comparative Example 10

(23) In Example 1, the same amount (2.0 parts by weight) of an aliphatic amine (Farmin 80, produced by Kao Corporation; melting point: about 49 to 51° C.) was used as the processing aid, the dispersibility was evaluated as “bad”, the compression set was not measurable, and the other items were evaluated as “good”.

Comparative Example 11

(24) In Example 1, the same amount (2.0 parts by weight) of a polyoxy alkyl ether acid (RL-210, produced by Toho Chemical Industry Co., Ltd.; melting point: about 55° C.) was used as the processing aid, the dimensional stability, dispersibility and compression set were evaluated as “bad” and the other items were evaluated as “good”.

Comparative Example 12

(25) In Example 1, the same amount (2.0 parts by weight) of a liquid hydrocarbon (polybutene NS-M15, produced by NOF CORPORATION; liquid at room temperature) was used as the processing aid, the dimensional stability and bleeding properties were evaluated as “bad,” and the other items were evaluated as “good”.

Comparative Example 13

(26) In Example 1, the same amount (2.0 parts by weight) of a solid hydrocarbon (Wax135, produced by NIPPON SEIRO CO., LTD; melting point: 60° C. or less) was used as the processing aid, the dimensional stability was evaluated as “bad” and the other items were evaluated as “good”.

Comparative Example 14

(27) In Example 1, the amount of fluorine-containing compound, which was a processing aid, was changed to 5 parts by weight, the compression set was evaluated as “bad” and the other items were evaluated as “good”.

Comparative Example 15

(28) In Example 1, the same amount (2.0 parts by weight) of a fluorine-containing compound (Dynamar FX5911, produced by 3M; melting point: 120° C.) was used as the processing aid, the processing aid was not dispersed, thereby failing to obtain a sample.