JP3314492B2 - Rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber composition.
More specifically, the present invention relates to a rubber composition having excellent resistance to chlorofluorocarbons and refrigerator oil.

[0002]

_2. Description of the Related Art At present, hydrogenated nitrile rubber or nitrile rubber is used for rubber parts (O-rings, packings, etc.) of air conditioners and the like using Freon R12 (CCl ₂ F ₂ ) as a refrigerant. CFC regulations are about to replace CFC R12 with CFC R134a (CH ₂ FCF ₃ ). However, hydrogenated nitrile rubber and 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 measures 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.

Accordingly, the present applicant has previously proposed a rubber composition obtained by adding an organic peroxide to a blended rubber of a hydrogenated nitrile rubber and chlorinated polyethylene (Japanese Patent Laid-Open No. 3-25).
0,037). This proposed rubber composition has Freon R1
Although it shows excellent resistance to both refrigerants 2 and R134a, and also to the mixture of these refrigerants and refrigerating machine oil, chlorinated as the main component (about 40 to 80% by weight) of the blended rubber Since polyethylene is used, the following problems have been observed. (1) Under extremely severe conditions such as high temperature and high humidity, the metal in contact therewith is corroded. (2) Some refrigeration oils have a large swelling property, and therefore the sealing property is reduced. (3) If chlorinated polyethylene is simply omitted in order to eliminate such problems, the resistance to chlorofluorocarbons, especially R134a, is reduced, and blisters occur.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to exhibit excellent resistance to both Freon R12 and Freon R134a refrigerants and all refrigerating machine oils used therein, and to further corrode metals. It is an object of the present invention to provide a rubber composition which can give a vulcanized molded article.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
In each case, about 5 to 145 parts by weight of carbon black and about 20 to 200 m ² / g of white carbon having a specific surface area of about 40 to 150 parts by weight, based on 100 parts by weight of hydrogenated nitrile rubber or nitrile rubber, are combined with an organic compound. Achieved by a rubber composition included with about 1 to 10 parts by weight of peroxide.

As the hydrogenated nitrile rubber, a rubber obtained by hydrogenating a copolymer rubber of acrylonitrile and butadiene (nitrile rubber) and reducing the amount of carbon-carbon double bonds in the molecular main chain to 10% or less is preferably used. However, in the present invention, the nitrile rubber itself can be used, and therefore, those having a double bond amount of 10% or more can also be used. Also,
Its Mooney viscosity ML _{1 + 4} (100 ° C)
About 85 are used, but 100 or more can also be used (see Japanese Patent Application Laid-Open No. 5-65,369). Practically, a commercially available product, for example, a product of Zeon product Zetpol series is used.

As the carbon black, furnace black produced by incompletely burning oil, thermal black produced by thermally decomposing natural gas, and the like are generally used, and these are commercially available for the rubber industry. The product can be used as it is.

[0010] As the white carbon, dry method white carbon produced by a thermal decomposition method of a halogenated silicic acid or an organic silicon compound or a method of heating and reducing silica sand to oxidize SiO, and thermal decomposition of sodium silicate and the like wet process white carbon produced by law or the like, a specific surface area (by nitrogen adsorption method) of about 20 to 200 m ² / g, preferably used is of about 30 to 100 m ² / g, they generally Commercial products marketed for the rubber industry can be used as they are. If the specific surface area is smaller than this, the reinforcing properties as white carbon cannot be obtained, and the CFC resistance is reduced. On the other hand, those having a larger specific surface area have a smaller white carbon particle diameter,
Problems such as poor dispersion in rubber occur.

These carbon blacks and white carbons are used in an amount of about 5 to 145 parts by weight, preferably about 1 to 100 parts by weight, per 100 parts by weight of hydrogenated nitrile rubber or nitrile rubber.
It is used in a proportion of 0 to 100 parts by weight. If these proportions are lower than these, all of them will be inferior to CFC R134a resistance, while if used at higher proportions, the rubber hardness will be very high and the rubber elasticity will be lost. Also, the total amount of these is about
It must be in the range of 40-150 parts by weight, preferably about 50-130 parts by weight.

The organic peroxide used as a hydrogenated nitrile rubber or a crosslinking agent for the nitrile rubber 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 organic peroxide is, for example, dicarboxylic acid. 3 butyl peroxide, dicumyl peroxide, tertiary 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)
Hexin-3, 1,3-di (tert-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxybenzoate,
Tributyl peroxyisopropyl carbonate, n-butyl-4,4-di (tertiary butyl peroxy) valerate and the like are used.

In the rubber composition, in addition to the above essential components, other functional agents such as triallyl (iso) cyanurate, trimethylolpropane trimethacrylate, triallyl trimellitate, and other reinforcing agents such as active calcium carbonate Fillers such as talc, clay, graphite and calcium silicate; processing aids such as stearic acid, palmitic acid and paraffin wax; acid acceptors such as magnesium oxide, hydrotalcite and epoxy resin; antioxidants; plasticizers A compounding agent commonly used in the rubber industry, such as, for example, is appropriately added and used as needed.

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.

[0015]

When carbon black and white carbon having a specific specific surface area are mixed with a hydrogenated nitrile rubber or a nitrile rubber, there is no problem in dispersibility and the mixture can be uniformly mixed. When such a rubber composition is crosslinked with an organic peroxide, it exhibits excellent resistance to both refrigerants R12 and R134a and all refrigerating machine oils used therein, and further has no metal corrosiveness.

Therefore, the rubber composition according to the present invention can be suitably used as a molding material for rubber parts such as O-rings, packings, oil seals used in air conditioners, refrigerators and the like using Freon R12 or Freon R134a. Can be.

[0017]

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

Examples 1-2, Comparative Examples 1-2 Hydrogenated nitrile rubber 100 parts by weight (Zepol 2020, manufactured by Zeon Corporation) Zinc oxide 5 Stearic acid 0.5 Diphenylamine anti-aging agent 1.5 Imidazole anti-aging agent 1.5 1,3 -Di (tert-butylperoxyisopropyl) benzene (concentration 40%) 10 adipic acid-based plasticizer 10 vinylsilane compound (Examples 1 and 2 and Comparative Example 2 only) 2 Each of the above components and carbon black (N-990 ) And white carbon (specific surface area 70 m ² / g) with the following specified amount (parts by weight) using a 3 L kneader and an open roll, and kneaded the mixture with primary vulcanization at 170 ° C for 20 minutes (press vulcanization). Vulcanization) and secondary vulcanization (oven vulcanization) for 3 hours at 160 ° C for 150 hours.
It was vulcanized and formed into a sheet of × 150 × 2 mm. Example Carbon Black White Carbon Comparative Example 1 90 0 Example 1 60 20 Example 2 30 40 Comparative Example 2 0 60

Example 3 In Example 2, instead of the hydrogenated nitrile rubber,
100 parts by weight of nitrile rubber (Nippon Zeon product DN108) was used.

Comparative Example 3 Hydrogenated nitrile rubber (Zetpol 2020) 50 parts by weight Chlorinated polyethylene (Eraslen 302NA, Showa Denko KK) 50 Carbon black (N-990) 60 Hydrotalcite 10 Stearic acid 0.5 Diphenylamine antioxidant 1.5 Vulcanization molding into a sheet using the imidazole-based antioxidant 1.5 1,3-di (tert-butylperoxyisopropyl) benzene (concentration 40%) 10 or more components was performed in the same manner as described above. .

The vulcanized sheets obtained in the above Examples and Comparative Examples were each measured for physical properties under normal conditions (JIS K-6301).
Compliance), immersion test (measures the volume change rate when immersed in paraffin oil, naphthenic oil, or polyglycol oil as a refrigerating machine oil at 150 ° C for 70 hours), CFC test (CFC
After immersion in R12 or Freon R134a at 25 ° C for 24 hours, 15
Appearance after heating for 1 hour in an oven at 0 ° C is observed with or without blisters) and a corrosion test (an SPCC plate is sandwiched between two vulcanized rubber sheets and left in an oven at 150 ° C for 200 hours) Then, the presence or absence of rust on the SPCC plate was observed). The results obtained are shown in the following table. Table item ratio-1 real-1 real-2 ratio-2 real-3 ratio-3 [Normal physical properties] Hardness (JIS A) 75 76 77 78 78 75 Tensile strength (MPa) 20.0 22.5 26.4 29.6 25.1 19.6 elongation (%) 350 300 240 200 230 190 [Immersion test; volume change rate] Paraffin oil (%) -3.2 -3.1 -2.9 -2.9 -3.2 +4.2 Naphthenic oil (%) +5.2 +5.4 +5.7 +6.1 +5.6 +24.4 Polyglycol oil (%) +1.0 +1.1 +1.1 +1.3 +1.0 -0.9 [Freon test; presence of blister] R12 None None None None None None R134a Yes None None None None None [Corrosion test; presence of rust] SPCC plate No No No No No No Yes

From the above results, in each embodiment, CFC R1
2, It is shown to be resistant to Freon R134a and all refrigerating machine oils and not corrode metals.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 9/02 C08K 3/04 C08K 3/36 C08K 5/14

Claims (1)

(57) [Claims] 1. A hydrogenated nitrile rubber or 100 parts by weight of nitrile rubber, each containing about 5 to 145 parts by weight of carbon black and about 20 to 200 m ² / g of white carbon in an amount of about 40 to 150 parts by weight. In total, about 1-10 organic peroxides
A rubber composition contained together with parts by weight.