JPS621745A - Fluororubber composition - Google Patents

Abstract

PURPOSE:The titled composition, obtained by incorporating a specific tetrafluoroethylene-propylene copolymer rubber with Austin Black and an organic peroxide and capable of providing packing materials retaining good permanent compression set properties for a long period even on contact with a high-temperature antifreeze. CONSTITUTION:A fluororubber composition obtained by incorporating (A) 100pts. wt. tetrafluoroethylene-propylene copolymer rubber having crosslinkage points in the molecule and 20-200 Mooney viscosity with (B) 1-100pts.wt. Austin Black having 5-7pH and (C) 0.1-20pts.wt., preferably 1-8pts.wt. organic peroxide, e.g. 2,5-methyl-2,5-di(tert-butylperoxy)hexane. USE:Sealing rubber packing materials used in contact parts of heat exchangers with an antifreeze in automotive engines.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a fluororubber composition.
The present invention relates to a tetrafluoroethylene-propylene copolymer rubber composition that can provide a packing material that can maintain good compression set characteristics for a long period of time even when exposed to high-temperature antifreeze.

[Conventional technology]

Automotive engines are being used under higher temperature conditions as automobiles become more efficient and fuel efficient. For this reason, the temperature range applied to antifreeze (long-life coolant) used in engine heat exchangers is also trending higher, from -30°C to +120°C.
Along with this, there has been a demand for the development of rubber seal materials for seals that can sufficiently withstand contact with high-temperature antifreeze.

Conventionally, EPDM-based rubber has been used as the sealing rubber packing material used in this type of heat exchanger, but the molded product of Tonogo 11 cannot be used in areas where lubricating oil is present. Recently, the use of silicone rubber, which has excellent lubricant resistance, is being considered.

However, it has been found that silicone rubber molded products are significantly susceptible to deterioration when they come into contact with antifreeze under high-temperature conditions, and as a result, the lifespan of the silicone rubber molded product as a sealing material is shortened.

[Problem that the invention seeks to solve]

In general, one of the functions required of rubber packing materials for seals is good compression set characteristics.

In response to these demands, silicone rubber packing materials with high crosslinking density and low filling rate have shown particularly excellent compression set characteristics when brought into contact with antifreeze for a short time.
If this continues for a long period of time, deterioration may occur and the seal may no longer function as a seal.

Therefore, the use of highly crosslinked density fluorinated ethylene-propylene copolymer rubber, which has good compression set characteristics even when in contact with antifreeze for a long period of time, was investigated. However, rubber packing materials for seals that come into contact with high-temperature antifreeze fluid are required not only to have compression set properties but also to have good antifreeze resistance. This antifreeze resistance requires good amine resistance in addition to water resistance, but highly crosslinked density fluorinated ethylene-propylene copolymer rubber is said to be degraded by the amines used in antifreeze. I have a problem.

It is now necessary to try to solve these problems, and as a result of repeated studies from the perspective of fillers to be added to rubber, the inventors have decided to mix Austin black, which has a higher acidity than general carbon black, as a filler. However, it has been found that by performing a neutralizing action thereby, a composition of tetrafluoroethylene-propylene copolymer rubber having good amine resistance and high crosslinking density can be obtained.

[Means for Solving the Problems] and [Operations] Accordingly, the present invention provides a fluororubber composition that can be effectively used as a molding material for sealing rubber packing materials used in antifreeze contact areas of heat exchangers of automobile engines. This fluororubber composition contains a tetrafluoroethylene-propylene copolymer rubber having crosslinking points in the molecule, Austin black, and an organic peroxide.

The tetrafluoroethylene-propylene copolymer rubber contains about 20 to 80 mol% of tetrafluoroethylene, generally 5
A rubbery copolymer copolymerized with 0 mol%, having a crosslinking point such as a double bond that can be crosslinked with an organic peroxide, and having a Mooney viscosity ML.

(100°C) of about 20 to 200 is used.

Austin black, which is used as a filler, is carbon black made from low-volatile bituminous coal.1While normal carbon blank has a pH of about 7 to 5, it has a pH of 115 to 7, which is slightly on the acidic side. This can be considered to have a neutralizing effect on amine-based antifreeze that exhibits weak alkalinity. Austin Black, which acts in this way, is made of tetrafluoroethylene-propylene copolymer rubber 100
Generally used in proportions of about 1 to 100 parts by weight.

Examples of organic peroxides include 1, such as 2,5-dimethyl-2,
5-di(tert-butylperoxy)hexane, di-tert-butyl peroxide, bis(2,4-dichlorobenzoyl)
Peroxide, bis(tert-butylperoxy)diisopropylbenzene, etc. are used in a proportion of about 0.1 to 20 parts by weight, preferably about 1 to 8 parts by weight, per 100 parts by weight of tetrafluoroethylene-propylene copolymer rubber. .

These organic peroxides include triallylisocyanurate, which is generally used in a proportion of about 0.1 to 20 parts by weight, preferably about 1 to 10 parts by weight, per 100 parts by weight of tetrafluoroethylene-propylene copolymer rubber. Used in the presence of a crosslinking aid.

Preparation of a tetrafluoroethylene-propylene copolymer rubber composition using each of the above components and molding using the same can be carried out using, for example, a closed mixer such as a Banbury mixer or an intermix kneader, or an open roll. ,
After stepwise kneading the tetrafluoroethylene-propylene copolymer rubber, Austin black, crosslinking aid, organic peroxide, etc., the mixture is heated in a mold of a predetermined shape to a temperature above the decomposition temperature of the organic peroxide, which is the crosslinking agent. This is done by heating. During kneading, celite, fine quartz powder, zinc white, calcium carbonate, talc, titanium dioxide, asbestos, glass fiber, etc. can be added as necessary.

〔Effect of the invention〕

Tetrafluoroethylene-propylene copolymer polymer according to the present invention
) When the composition is used as a molding material and molded into a rubber seal material for sealing used at antifreeze contact points of heat exchangers of automatic + Ig-engines.

To provide a packing material that exhibits superior physical properties compared to those molded from silicone rubber even when in contact with ordinary antifreeze for a long period of time, and in particular has good compression set characteristics even when in contact with high temperature antifreeze.

〔Example〕

Next, the present invention will be explained with reference to examples. ·Example].

Tetrafluoroethylene-propylene copolymer rubber (mole ratio 50
: 50 alternating copolymer; Mooney viscometer, +412
0) Knead 100 parts by weight, 15 parts by weight of Austin black, and 2 parts by weight of 1 to 2 parts by weight of stearate using any mixing means described above, and when the contents become almost uniform,
1 to Realyl Isocyanate h (
5 parts by weight of peroxydiisopropylbenzene (40% content) and 2.5 parts by weight of peroxydiisopropylbenzene (40% content) were added and kneaded uniformly again.
Primary vulcanization at 0°C for 10 minutes and secondary vulcanization at 230°C for 4 hours resulted in a wire diameter of 5.3 @ inner diameter 10W.
rn O-ring was vulcanized and molded.

Example 2 In Example 1, another polytetrafluoroethylene-propylene copolymer rubber (Mooney viscosity M1.1+480) was used.

Comparative Example In Example 1, instead of Austin Bragg, MT
Carbon black was used in the 25-layer seam.

6 of the O-rings obtained in each of the following examples and the ratio C bite case.
For the equal parts, various items were all determined. The measurement method was as follows, and the obtained results are shown in the table below.

(Al!I determination of physical property values) According to J-S K-6301 (immersion test) A compression set test jig (compress the sample and #Procedure Amendment July 30, 1985 Pour the test liquid until it sufficiently covers the jig, seal it, and then place the pressure-resistant container in an oven at the set temperature

Claims (1)

[Scope of Claims] 1. A fluororubber composition comprising a tetrafluoroethylene-propylene copolymer rubber having crosslinking points in the molecule, Austin black, and an organic peroxide. 2. Approximately 1 to 100 parts by weight of Austin black and approximately 0.1 to 20 parts by weight of an organic peroxide are blended per 100 parts by weight of tetrafluoroethylene-propylene copolymer rubber. Fluororubber composition. 3. The fluororubber composition according to claim 1, which is used as a molding material for a rubber packing material for sealing used in antifreeze contact areas of heat exchangers of automobile engines.