JPH07118447A - Rubber composition - Google Patents

Abstract

PURPOSE:To obtain a rubber composition, capable of providing a vulcanized molding capable of manifesting excellent resistance to both refrigerants of fluorocarbons R12 and R134a and all the refrigerator oils used therefor without corroding metals. CONSTITUTION:This rubber composition contains 100 pts.wt. hydrogenated nitrile rubber or nitrile rubber with about 5-145 pts.wt. carbon black and about 5-145 pts.wt. white carbon having about 20-200m<2>/g specific surface area in the total amount of about 40-150 pts.wt. together with about 1-10 pts.wt. organic peroxide.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a rubber composition.
More specifically, it relates to a rubber composition having excellent resistance to freon and refrigerating machine oil.

[0002]

_2. Description of the Related Art Currently, hydrogenated nitrile rubber or nitrile rubber is used for rubber parts (O-rings, packings, etc.) of air conditioners, etc., which use Freon R12 (CCl ₂ F ₂ ) as a refrigerant. Freon R12 is about to be replaced by Freon R134a (CH ₂ FCF ₃ ) due to Freon regulations. However, hydrogenated nitrile rubber and nitrile rubber have a drawback that they foam when they come into contact with Freon R134a.

On the other hand, ethylene / propylene copolymer rubbers have excellent resistance to CFCs R134a, while ethylene / propylene copolymer rubbers are conversely CFCs.
It has the drawback of foaming when it comes into contact with R12.

As described above, at present, Freon R12 to Freon R13
Although it is about to be replaced by 4a, there are various problems associated therewith, and it is the current situation that all of the Freon R12 are replaced by Freon R134a. As a measure during this period, Freon R12 and Freon R134a are to be used respectively, and therefore there is a demand for a rubber composition that can be used for both Freon R12 and Freon R134a refrigerants.

Therefore, the present applicant has previously proposed a rubber composition obtained by adding an organic peroxide to a blend rubber of hydrogenated nitrile rubber and chlorinated polyethylene (Japanese Patent Application Laid-Open No. 3-25 / 1993).
No. 0,037). This proposed rubber composition uses Freon R1
Although it has excellent resistance to both refrigerants 2 and R134a, and a mixed liquid of these refrigerants and refrigerating machine oil, it is 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) For example, under extremely severe conditions such as high temperature and high humidity, the mating metal that comes into contact with this is corroded. (2) The swelling property is large for some refrigerating machine oils, and thus the sealing property is deteriorated. (3) To eliminate these problems, simply omitting chlorinated polyethylene will reduce the resistance to CFCs, especially R134a, and cause blistering.

[0006]

The object of the present invention is to show excellent resistance to both CFC R12 and CFC R134a refrigerants and all refrigerating machine oils used therein, and to corrode metals. An object of the present invention is to provide a rubber composition capable of giving a vulcanized molded article.

[0007]

The object of the present invention is as follows.
About 100 parts by weight of hydrogenated nitrile rubber or nitrile rubber, in each case about 5 to 145 parts by weight of carbon black and specific surface area of about 20 to 200 m ² / g of white carbon in a total amount of about 40 to 150 parts by weight, organic This is accomplished with a rubber composition included with about 1 to 10 parts by weight peroxide.

As the hydrogenated nitrile rubber, it is preferable to use a copolymerized rubber (nitrile rubber) of acrylonitrile and butadiene which is hydrogenated so that the amount of carbon-carbon double bonds in the molecular main chain is 10% or less. However, since the nitrile rubber itself can be used in the present invention, it is also possible to use one having a double bond content of 10% or more. Also,
About its Mooney viscosity ML _{1 + 4} (100 ℃), generally 60 ~
Although about 85 is used, 100 or more can also be used (see JP-A-5-65,369). In practice, commercially available products such as those manufactured by Nippon Zeon's Zet Pole series are used.

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

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 thermally reducing silica and oxidizing SiO, 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 Commercially available products that are marketed for the rubber industry can be used as they are. When the specific surface area is smaller than this, the reinforcing property as white carbon cannot be obtained, and the CFC resistance is lowered. On the other hand, if the specific surface area is larger than this, the particle size of white carbon becomes smaller,
This causes problems such as poor dispersion in rubber.

Each of these carbon blacks and white carbons is about 5-145 parts by weight, preferably about 1 part 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 the proportion is less than this, all of them will be inferior to the CFC R134a resistance. On the other hand, if the proportion is more than these, the rubber hardness will be extremely high and the rubber elasticity will also be lost. For the same reason as above, the total amount of these is approximately
It should be in the range of 40 to 150 parts by weight, preferably about 50 to 130 parts by weight.

The organic peroxide used as a cross-linking agent for hydrogenated nitrile rubber or a 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, may be, for example, a diamine. 3-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide,
1,1-di (tertiary butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (tertiary butylperoxy)
Hexane, 2,5-dimethyl-2,5-di (tertiary butylperoxy)
Hexine-3,1,3-di (tert-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxybenzoate, tert-butyl
3-Butylperoxyisopropyl carbonate, n-butyl-4,4-di (tertiary butylperoxy) valerate and the like are used.

In the rubber composition, in addition to the above essential components, polyfunctional compounds such as triallyl (iso) cyanurate, trimethylolpropane trimethacrylate and triallyl trimellitate, and other reinforcing agents such as activated 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 Compounding agents generally used in the rubber industry such as are appropriately added and used as necessary.

The rubber composition is prepared by kneading using an intermix, kneader, Banbury mixer or the like, or using an open roll, and the vulcanization thereof is performed by an injection molding machine, a compression molding machine, or a vulcanization machine. Generally, it is performed by heating at about 150 to 200 ° C for about 3 to 60 minutes using a sulfur press or the like, and at about 120 to 200 ° C for about 1
Secondary vulcanization is performed by heating for ~ 24 hours.

[0015]

EFFECTS OF THE INVENTION When hydrogenated nitrile rubber or nitrile rubber is mixed with carbon black and white carbon having a specific surface area, there is no problem in dispersibility and the like and they can be mixed uniformly. When such a rubber composition is cross-linked with an organic peroxide, it exhibits excellent resistance to both refrigerants of CFC 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 is preferably used as a molding material for rubber parts such as O-rings, packings and oil seals used in air conditioners, refrigerators and the like which use Freon R12 or Freon R134a. You can

[0017]

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

Examples 1 and 2, Comparative Examples 1 and 2 Hydrogenated nitrile rubber 100 parts by weight (Zeon Corporation ZEPTPOL 2020) Zinc oxide 5 Stearic acid 0.5 Diphenylamine anti-aging agent 1.5 Imidazole anti-aging agent 1.5 1,3 -Di (tertiary butylperoxyisopropyl) benzene (concentration 40%) 10 Adipic acid 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) and the following predetermined amount (parts by weight) were kneaded using a 3 L kneader and an open roll, and this kneaded product was subjected to primary vulcanization (press vulcanization at 170 ° C. for 20 minutes). 150) by secondary vulcanization (oven vulcanization) for 3 hours at 160 ° C.
It was vulcanized and molded 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 hydrogenated nitrile rubber,
Nitrile rubber (Nippon Zeon product DN108) was used in 100 parts by weight.

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 anti-aging agent 1.5 Imidazole anti-aging agent 1.5 1,3-di (tertiary butylperoxyisopropyl) benzene (concentration 40%) 10 Vulcanization molding into a sheet using each of the above components was performed in the same manner as above. .

For the vulcanized sheets obtained in each of the above Examples and Comparative Examples, measurement of normal state physical properties (JIS K-6301
Conformity), immersion test (measure the volume change rate when immersed in paraffin oil, naphthene oil or polyglycol oil which is a refrigerating machine oil at 150 ° C for 70 hours), CFC test (CFC)
After soaking in R12 or Freon R134a at 25 ℃ for 24 hours,
Observe the appearance condition when heated in an oven at 0 ° C for 1 hour with or without blisters) and corrosion test (sandwich the SPCC plate between two vulcanized rubber sheets and leave it 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 Naphthene 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 / absence of blisters] R12 None None None None None None R134a Yes None None Yes None None [Corrosion test; presence of rust] SPCC plate No No No No No No Yes

From the above results, in each of the examples, CFC R1
2, resistant to Freon R134a and all refrigeration oils and has been shown to not corrode metals.

Claims (1)

[Claims] 1. 100 parts by weight of 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 40 to 150 parts by weight of white carbon having a specific surface area of about 20 to 200 m ² / g. About 1 to 10 organic peroxides in total
A rubber composition which is contained together with parts by weight.