JP3301127B2 - Rubber parts with excellent Freon refrigerant resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates, immediately resistance to Freon refrigerant resistance
Rubber parts . For more details, Freon resistance R134a
The present invention relates to rubber parts having excellent refrigerant properties.

[0002]

2. Description of the Related Art At present, Freon R12 (CCl2F2) is used as a refrigerant.
Rubber parts (O-rings, packings, etc.) and air-conditioning is used to include, nitrile rubber or hydrogenated nitrile rubber is used, CFC R12 by CFC restrictions are alternatives to CFC R134a (CH ₂ FCF ₃₎ I am trying to do. However, nitrile rubber and hydrogenated nitrile rubber have a disadvantage that they foam when contacted with Freon R134a.

On the other hand, ethylene-propylene copolymer rubber has excellent resistance to Freon R134a, but ethylene-propylene copolymer rubber
It has the disadvantage of foaming on contact with R12.

[0004] As described above, CFCs R12 to C13
Although it is about to be replaced by 4a, there are various problems associated therewith, and at present, there is a considerable amount of time before all CFCs R12 are replaced by CFCs R134a. As a measure during this time, Freon R12 and Freon R134a will be used, respectively.Therefore, a rubber composition that can be used for both refrigerants Freon R12 and Freon R134a has been demanded. Rubber composition is not provided.

[0005] The present applicant has previously disclosed a rubber composition exhibiting excellent resistance to both refrigerants R12 and R134a, containing hydrogenated nitrile rubber, chlorinated polyethylene and organic peroxide. (Japanese Patent Laid-Open Publication No. 3-250,037).

[0006] Such a rubber composition achieves its intended purpose, but when hydrogenated nitrile rubber is used in a proportion of about 60% by weight or more, the resistance to Freon R134a deteriorates and foaming is performed. It is stated to be.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rubber component which does not reduce the CFC R134a resistance and does not foam even when a hydrogenated nitrile rubber is used in a blend rubber at a ratio of about 60% by weight or more. Is to provide.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
65-85 made of an organic peroxide crosslinked product of a blend rubber of weight% of hydrogenated nitrile rubber and 35 to 15% by weight of chlorinated ethylene-propylene copolymer rubber, Freon R134a (CH ₂ FCF
₃ ) Achieved by rubber parts used at the contact points .

As the hydrogenated nitrile rubber, those obtained by hydrogenating a copolymer rubber of acrylonitrile and butadiene to reduce the amount of carbon-carbon double bonds in the molecular main chain to 10% or less are generally used. A commercially available product such as Zeon Poll from Nippon Zeon can be used as it is. As the chlorinated ethylene / propylene copolymer rubber, a commercially available product (Miprene, Mitsui Petrochemical Co., Ltd.) can be used as it is.

In both cases, the hydrogenated nitrile rubber is 65%.
The chlorinated ethylene / propylene copolymer rubber is used at a ratio of 35 to 15% by weight. The hydrogenated nitrile rubber can be used at a blending ratio lower than this, but in this case, there is no particular difference in the effect as compared with the case where the rubber is blended with chlorinated polyethylene.

[0011] These blended rubbers are cross-linked by an organic peroxide generally used in an amount of about 1 to 10 parts by weight, preferably about 2 to 8 parts by weight, per 100 parts by weight of the blended rubber. As the organic peroxide, for example, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, 1,1-di (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 2 , 5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3,1,3-di (tert-butyl Peroxyisopropyl) benzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxybenzoate, tert-butylperoxyisopropylcarbonate, n-butyl-4,4-di For example, 3-butylperoxy) valerate is used.

In the rubber composition, in addition to the above essential components, triallyl (iso) is used as a compounding agent for each rubber.
Polyfunctional compounds such as cyanurate, trimethylolpropane trimethacrylate, triallyl trimellitate, reinforcing agents such as carbon black and fine silica, fillers such as talc, clay, graphite, calcium silicate, stearic acid, palmitic acid, Processing aids such as paraffin wax, acid acceptors such as magnesium oxide, hydrotalcite and epoxy resin, compounding agents commonly used in the rubber industry such as antioxidants and plasticizers are added as needed. It is used.

The rubber composition is prepared by kneading using a kneading machine such as an intermix, kneader, Banbury mixer or an open roll, and vulcanizing the same using an injection molding machine, a compression molding machine, a vulcanizing machine, or the like. It is generally carried out by heating at about 150 to 200 ° C. for about 3 to 60 minutes using a sulfur press or the like.
Secondary vulcanization with heating for ~ 24 hours is performed.

[0014]

When the hydrogenated nitrile rubber and the chlorinated ethylene / propylene copolymer rubber are blended, there is no problem in the compatibility between the two and mixing can be performed without causing micro-interface separation. .

When such a blended rubber is crosslinked with an organic peroxide, properties which cannot be obtained with a single rubber,
That is, a rubber component having excellent resistance to both refrigerants, Freon R12 and Freon R134a, is provided.

Accordingly, the organic peroxide from the blended rubber composition containing the hydrogenated nitrile rubber according to the present invention as a main component is obtained.
The cross-linked product is in contact with freon R134a for machines using freon R12 or freon R134a, such as air conditioners and refrigerators.
It can be suitably used as rubber parts such as O-rings and packings used in places .

[0017]

Next, the present invention will be described with reference to examples.

Example 1 Hydrogenated NBR (Zepol 1020 manufactured by Nippon Zeon Co., Ltd.) 80 parts by weight Chlorinated EPDM (Miprene CE3100, Mitsui Petrochemicals) 20 Carbon black (N-990) 90 Magnesium oxide 52 2-Mercaptobenzimidazole 0.5 poly (2,2,4-trimethyl-1,2-dihydroquinoline) 0.5 Epoxy resin (Epototo YD-128 manufactured by Toto Kasei) 2 Dicumyl peroxide 6 Triallyl isocyanurate 3

Hydrogenated NBR and chlorinated ethylene / propylene copolymer rubber (chlorinated EPDM) were kneaded with a kneader, and then kneaded with an open roll so as to have a weight ratio of 80:20. This blended rubber composition was heated at 170 ° C for 2 hours.
After press vulcanization for 0 minutes, secondary vulcanization was performed in a heating oven at 160 ° C. for 3 hours to obtain a vulcanized sheet of 150 × 150 × 2 mm.

Example 2 In Example 1, the amount of hydrogenated NBR was changed to 70 parts by weight and the amount of chlorinated EPDM was changed to 30 parts by weight.

Comparative Example In Example 1, chlorinated polyethylene (Eraslen manufactured by Showa Denko) was used in the same amount instead of chlorinated EPDM.

With respect to each vulcanized sheet obtained in each of the above examples, the physical properties under normal conditions (according to JIS K-6301) and the volume change rate after immersion in Freon R12 or Freon R134a for 24 hours (25 mm
A disc-shaped rubber sheet having a diameter and a thickness of 2 mm was immersed in 200 g of chlorofluorocarbon at 40 ° C), and the foaming state of the surface after heating at 160 ° C for 30 minutes was observed. The results obtained are shown in the following table. Table Example 1 Example 2 Comparative Example [Physical properties in normal state] Hardness (JIS A) (Point) 81 81 81 Tensile strength (MPa) 21.2 20.8 21.7 Elongation (%) 200 200 200 [Freon resistance R12] Volume change Rate (%) +5.9 +6.4 +5.5 Foaming state No No No [Freon resistance to R134a] Volume change rate (%) +9.2 +8.1 +9.1 Foaming state No Yes

Claims (1)

(57) [Claims] 1. A hydrogenated nitrile rubber of 65-85% by weight and 3
5 to 15% by weight chlorinated ethylene / propylene copolymer rubber
Made of an organic peroxide crosslinked product of a blend rubber of furo
Rubber parts used for R134a (CH ₂ FCF ₃ ) contact points.