JPH10182882A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition prepared by adding carbon black to a hydrogenated nitrile rubber and being capable of giving a molding, such as a seal member of a car air conditioner, excellent in blistering resistance and abrasion resistance when vulcanization-molded. SOLUTION: This composition comprises a hydrogenated nitrile rubber having a nitrile content of 30-50wt.%, an iodine value of 30 or below, and a Mooney viscosity of 50-150 (MLI+4 , 100 deg.C) and a carbon flack having a specific surface area of 80-160m<2> /g, a compression DBP absorption of 100-130ml/100g, a specific tinting strength of 100-140, a nitrogen adsorption specific surface area/iodine adsorption ratio of 1.0-1.25 and an electron microscope mean particle diameter of 15-30nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a rubber composition. More specifically, the present invention relates to a rubber composition suitably used as a material for forming a seal member of a compressor for a car air conditioner.

[0002]

2. Description of the Related Art JP-A-7-30490 discloses (a) a nitrile content of 30 to 50% by weight, an iodine value of 30 or less, and a Mooney viscosity of ML _{1 + 4.}
(100 ° C.) 50 to 150 of the hydrogenated nitrile rubber, (b) a specific surface area of 100~170m ² / g, an oil absorption of 180~220ml / 100g silicon dioxide and (c) a specific surface area of 10 m ² / g or less of It is stated that a rubber composition containing silicon dioxide is suitably used as a sealing member molding material for a compressor for a car air conditioner. However, neither the fluorohydrocarbon resistance (blister resistance) under high-temperature conditions nor the abrasion resistance required as a dynamic seal member of a vulcanized seal member is satisfactory.

[0003] Further, a rubber composition for forming an O-ring for use in a compressor for a refrigerator, which is obtained by adding carbon black to a hydrogenated nitrile rubber, has been previously proposed by the present applicant (Japanese Patent Publication No. 5-17930). Publication), the carbon blacks described here are MT, SRF, FEF, HAF (N-
330), various grades generally used such as ISAF, and it is stated that it is preferable to use highly reinforcing carbon. However, when such a grade of carbon black was added to the hydrogenated nitrile rubber and the sealing member of the compressor for a car air conditioner was vulcanized, it was recognized that blister resistance and wear resistance were not satisfactory. Was.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rubber composition obtained by adding carbon black to hydrogenated nitrile rubber. It is an object of the present invention to provide a material capable of providing excellent blister properties and abrasion resistance.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
(a) a nitrile content of 30 to 50 wt%, iodine value 30 or less, Mooney viscosity _{ML 1 + 4 (100 ℃)} 50~150 hydrogenated nitrile rubber and (b) a specific surface area 80~160m ² / g, compression DBP oil absorption 100-130m
l / 100 g, specific coloring power of 100 to 140, nitrogen adsorption specific surface area / iodine adsorption ratio of 1.0 to 1.25, and a rubber composition containing carbon black having an electron microscope average particle size of 15 to 30 nm.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The hydrogenated nitrile rubber of the component (a) has a nitrile content range in terms of oil resistance, an iodine value range in terms of heat resistance, and a blister resistance and processability. The Mooney viscosity ML _{1 + 4} (100 ° C.) whose range is specified as described above is used.

As the carbon black of the component (b), those having the above-mentioned respective characteristic values in terms of blister resistance, abrasion resistance and workability are used. With respect to the specific surface area, if it is less than this, the effect of improving the blister resistance and wear resistance is small, while if it is more than this, the workability is greatly reduced. Regarding the compressed DBP oil absorption, if it is less than this, the effect of improving the blister resistance and abrasion resistance is small, while if it is more than this, the reduction in blister resistance and workability will be large. Regarding the specific coloring power (JIS K-6221), the improvement in blister resistance and abrasion resistance is small when the specific coloring power is lower than this, while the workability is greatly reduced when the specific coloring power is higher than this. Nitrogen adsorption specific surface area (BET method) / Iodine adsorption amount (JI
Regarding the ratio of SK-6221), if the ratio is lower than this, the effect of improving the wear resistance is small, while if it is higher, the workability is greatly reduced. Further, with respect to the average particle size of the electron microscope, if the average particle size is smaller than this, the workability is greatly reduced, whereas if the average particle size is larger than this, the effect of improving the blister resistance and the wear resistance is small. These carbon blacks are used in a proportion of about 30 to 100 parts by weight, preferably about 35 to 65 parts by weight, per 100 parts by weight of the hydrogenated nitrile rubber.

A rubber composition obtained by adding carbon black having such characteristic values to a blend rubber of a natural rubber and a diene rubber (such as isoprene rubber, butadiene rubber, and styrene-butadiene copolymer rubber) is disclosed in No.-230290, this rubber composition is said to be suitable for pneumatic tires, especially for high-load pneumatic tires with excellent abrasion resistance, fluorocarbon resistant It can be said that the blister resistance is not related to the blister resistance.

The composition is prepared by adding a vulcanizing agent and other necessary components in addition to the above essential components, and kneading the mixture using an open roll, kneader, Banbury mixer, or the like. Is carried out according to the usual vulcanization conditions for hydrogenated nitrile rubber.

As a sealing member of a compressor for a car air conditioner vulcanized and molded from such a rubber composition, a lip seal, an O-ring and the like can be mentioned.

[0011]

The seal member vulcanized and formed from the rubber composition according to the present invention is resistant to cracks even when it is brought into contact with fluorohydrocarbons, especially at high temperatures. It is excellent in blister properties, and has good abrasion resistance required for dynamic sealing. Therefore, it is suitable as a sealing member used for a cooling device or an air conditioner, particularly a compressor for a car air conditioner.

[0012]

Next, the present invention will be described by way of examples.

Examples 1-2, Comparative Examples 1-2 Hydrogenated nitrile rubber (Zetpol 2010H manufactured by Nippon Zeon; 100 parts by weight CN content 36%, iodine value 11, Mooney viscosity 127) Carbon black A (Example 1) 45 〃 Carbon black B (Example 2) 45 〃 Carbon black N220 (Comparative example 1) 45 〃 Carbon black N330 (Comparative example 2) 50 〃 Antioxidant (Ouchi Emerging Chemicals Nocrack MBZ) 1.5 〃 Antioxidant ( Uniroyal product Now guard # 445) 1.5 亜 鉛 Zinc oxide 3 〃 Organic peroxide (Nippon Oil & Fats product Peroximon F-40) 6 〃 Knead the above ingredients with open roll for about 25 minutes to prepare rubber composition did. The carbon black used here has the following characteristic values (manufacturer-provided values). Carbon specific surface area compression DBP absorption N ₂ adsorption specific surface area mean particle size black ^{(m 2 / g) (ml} / 100g) ratio tinting strength / I ₂ adsorption amount (nm) A 123 100 124 1.041 20 B 135 116 134 1.120 18 N220 114 98 120 0.898 19 N330 85 92 110 1.098 35

The obtained rubber composition is subjected to press vulcanization (primary vulcanization) at 180 ° C. for 8 minutes and oven vulcanization (secondary vulcanization) at 165 ° C. for 1 hour to obtain JIS B-2401 P50. O-rings and sheets (150 × 150 × 2 mm) were vulcanized and molded, and the blister resistance and wear resistance were measured. Blister resistance (fluorohydrocarbon resistance) test: O-ring was immersed in hydrofluorocarbon 134a at 40 ° C. for 48 hours, then heated in an oven at 200 ° C. for 1 hour, and its appearance was visually checked for cracks. Evaluation Abrasion resistance test: Using a pin-on-disk abrasion tester,
Measure the amount of wear when the vulcanized sheet is worn under the conditions of 500 g load, 500 rpm, 7 hours

Comparative Example 3 60 parts by weight of natural rubber (RSS # 1) SBR (Japanese synthetic rubber product # 1500) 40 カ ー ボ ン carbon black A 45 〃 stearic acid 2 亜 鉛 zinc oxide 3 イ オ sulfur 1 〃 vulcanization accelerator (Ouchi Emerging Chemicals Noxeller M) 1 〃 Antioxidant (Ouchi Emerging Chemicals Nocrack DP) 1 を Kneading and vulcanizing each of the above components in the same manner as in Examples 1-2 (however, press vulcanization time is 20 Min, the oven vulcanization time was changed to 2 hours) and vulcanization molding was performed, and the blister resistance and abrasion resistance were measured.

The results obtained in the above Examples and Comparative Examples are shown in the following table.

[Procedure amendment]

[Submission date] February 21, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Correction contents]

Further, a rubber composition for molding an O-ring used for a compressor for a refrigerator, in which carbon black is added to a hydrogenated nitrile rubber, has been previously proposed by the present applicant (Japanese Patent Publication No. 5-17930). ), The carbon blacks described herein are MT, SRF,
It is of various grades commonly used, such as FEF, HAF (N-330), and ISAF, and it is stated that it is preferable to use highly reinforcing carbon. However, when such a grade of carbon black was added to the hydrogenated nitrile rubber and the sealing member of the compressor for a car air conditioner was vulcanized, it was recognized that blister resistance and wear resistance were not satisfactory. Was.

Claims (2)

[Claims] (1) (a) a nitrile content of 30 to 50% by weight, an iodine value
30 or less, Mooney viscosity ML _{1 + 4} (100 ° C) 50-150 hydrogenated nitrile rubber and (b) specific surface area 80-160 m ² / g, compressed DBP
A rubber composition containing carbon black having an oil absorption of 100 to 130 ml / 100 g, a specific coloring power of 100 to 140, a nitrogen adsorption specific surface area / iodine adsorption ratio of 1.0 to 1.25, and an average particle size of 15 to 30 nm by an electron microscope. 2. The rubber composition according to claim 1, which is used as a molding material for a seal member of a compressor for a car air conditioner.