JPH10158458A - Fluoro rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fluororubber composition not problematic in that the plasticizer volatilizes during post vulcanization or from a vulcanizate and capable of giving vulcanized rubber articles having a low hardness and reduced compression set by mixing a fluororubber with a vulcanizing agent and a liquid epichlorohydrin polymer. SOLUTION: This composition comprises a fluororubber such as a vinylidene fluoride type fluororubber or a vinylidene fluoride/hexafluoropropylene fluororubber, a vulcanizing agent and a liquid epichlorohydrin polymer. The vulcanizing agent used is a polyamide, a polyol or an organic peroxide. The polyamine vulcanizing agent is exemplified by hexamethylenediamine carbamate, and the polyol vulcanizing agent is exemplified by bisphenol AF. The composition is desirably one containing 100 pts.wt. fluororubber and 3-150 pts.wt. liquid epichlorohydrin rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition containing a large amount of a plasticizer, which solves the problem of volatilization of the plasticizer during post-vulcanization and contamination of OA equipment.
And enables the production of vulcanizates with small compression set,
The present invention relates to a fluororubber composition suitable for producing sealing materials and rolls for various OA equipment.

[0002]

2. Description of the Related Art Fluororubber has been used as a material having high heat resistance and chemical resistance, in the past, in fuel hoses, sealing materials such as packings, automotive parts such as diaphragms, and other fields. In recent years, along with the high performance of OA equipment, fluoro rubber has low hardness (JIS A hardness of 3) taking advantage of its excellent heat resistance, electrical insulation and chemical resistance.
(Approximately 0 to 50) as rolls and various sealing materials.

[0003] Fluoro rubber is originally JIS A hardness of 7
It is a rubber suitable for producing vulcanized rubber products of about 0 to 80, and various attempts have been made to reduce the hardness, but there are problems to be solved respectively. For example, when the blending amount of carbon black or the like is reduced, the hardness is reduced to some extent, but since the fluororubber is originally a hard rubber, the reduction in the hardness is limited, and the reinforcing effect cannot be obtained. Therefore, the mechanical strength decreases.

Further, a method of adding a large amount of a plasticizer such as DOP to fluororubber is an inexpensive method. However, not only does the plasticizer volatilize during post-vulcanization (secondary vulcanization), it also causes vulcanization. There is a problem that the plasticizer volatilizes over time even during use as a vulcanized rubber product. The method of using liquid fluororubber or silicon fluoride oil instead of plasticizer solves the problem of volatilization of plasticizer, but liquid fluororubber and the like are expensive and their applications are limited, and there is a problem that they are not trivial. Although the hardness can be lowered, there is a problem that the compression set, which is a property opposite to the hardness, increases.

Although methods other than those described above have been studied, none of these methods satisfy the performance required for low-hardness vulcanized fluororubber, which requires low hardness and low compression set. Improvement is required.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to evaporate a plasticizer even during post vulcanization and during use of a vulcanized product. An object of the present invention is to provide a fluororubber composition capable of producing a vulcanized rubber product having no problem, low hardness and low compression set.

[0007]

According to the present invention,
Provided are a fluororubber composition obtained by blending a vulcanizing agent and a liquid epichlorohydrin polymer with fluororubber, and a vulcanized fluororubber article obtained by vulcanizing the composition.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

Next, the present invention will be described in detail with reference to preferred embodiments. As the fluororubber used in the present invention, any conventionally known fluororubber can be used and is not particularly limited. For example, vinylidene fluoride (VD
F) -based fluororubbers are typical, and VDF-HF
P (hexafluoropropylene) -based fluoro rubber (AUSIMO
NTF's Technoflon, 3M's Hluorel, du Pont's Viton, etc.), VDF-HFP-TFE (tetrafluoroethylene) fluororubber (AUSIMONT's Technoflo)
n, Hluorel manufactured by 3M, Viton manufactured by du Pont, Miraflon manufactured by Asahi Kasei Kogyo), VDF-PFE (pentafluoroethylene) fluoro rubber (Techno manufactured by AUSIMONT)
flon), VDF-PFP-TFE-based fluoro rubber (AUSIMO
Binary to ternary fluororubbers such as NTN's Technoflon); T
FE-P (propylene) -based fluororubber (Afras manufactured by Asahi Glass Co., Ltd.); TFE-perfluoroalkylvinylether-based fluororubber; fluorosilicone rubber; fluoro-substituted phosphazene rubber.

As the vulcanizing agent for fluororubber used in the present invention, any conventionally known vulcanizing agent for fluororubber can be used and is not particularly limited. Usually, a polyamine, a polyol or an organic peroxide is used as a vulcanizing agent,
A vulcanizing agent that satisfies the characteristics required for the vulcanized fluoro rubber article is selected and used.

Examples of the polyamine vulcanizing agent include hexamethylene diamine carbamate, N, N'-dicinnamylidene-1,6-hexanediamine, and 4,4'-bis (aminocyclohexyl) methane carbamate. When using a polyamine vulcanizing agent, it is necessary to use an acid acceptor to increase the vulcanization efficiency and to neutralize the acidic substances generated during the vulcanization reaction. A combination of lead, calcium oxide, zinc white and dibasic lead phosphite is used. The amount of the polyamine vulcanizing agent is usually about 0.5 to 5 parts by weight per 100 parts by weight of the fluororubber (the same applies hereinafter), and the amount of the acid acceptor is usually about 3 to 25 parts by weight. is there.

Examples of the polyol vulcanizing agent include bisphenol AF, 1,1-bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl)
Compounds having a phenolic OH group such as polyhydroxy aromatic compounds such as -1,1-dimethylmethane and p, p'-dihydroxybenzene are exemplified. When this vulcanizing agent is used, usually, a phosphonium salt, a quaternary ammonium salt or the like is used as a vulcanization accelerator. still,
It is necessary to use an acid acceptor like the polyamine vulcanizing agent,
As the acid acceptor, calcium hydroxide, magnesium oxide, or the like is used. Usually, the amount of the polyol vulcanizing agent used is 0.1.
The amount of the vulcanization accelerator is about 0.1 to 1 part by weight, and the amount of the acid acceptor is usually about 3 to 25 parts by weight.

As the organic peroxide vulcanizing agent, for example,
2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-di (t-butylperoxy) hexane-3,1,1-bis (t-butylperoxy)-
3,3,5-trimethylcyclohexane, n-butyl-
4,4-bis (t-butylperoxy) valerate,
α, α'-bis (t-butylperoxyisopropyl)
Benzene and the like can be mentioned. In this case, a polyfunctional compound such as triallyl isocyanurate or trimethylolpropane trimethacrylate can be used as a co-vulcanizing agent. Usually, the amount of the organic peroxide vulcanizing agent used is
0.5 to 5 parts by weight, the amount of co-vulcanizing agent used is 0.5 to 1
It is about 0 parts by weight.

Although the vulcanizing agent and the like used in the present invention have been described above, the type and amount of the vulcanizing agent, the acid acceptor, the vulcanization accelerator and the co-vulcanizing agent are determined by using the composition of the present invention. It can be determined so as to satisfy the performance required for the vulcanized rubber article manufactured by the above method, and in the present invention, these types and amounts are not limited.

The liquid epichlorohydrin rubber used in the present invention is a homopolymer of epichlorohydrin, or 30 mol% or more of epichlorohydrin and ethylene oxide.
70 mol% or less of at least one alkylene oxide such as propylene oxide and / or unsaturated epoxide 15
Mol% or less, having a reduced viscosity (η _sp / c) at 35 ° C. of a toluene solution (concentration: 0.01 g / ml) of 0.01 to 0.5, preferably 0.03
-0.3 low molecular weight polymer. If the reduced viscosity exceeds 0.5, the effect of lowering the hardness of the fluororubber is small. Such a liquid epichlorohydrin rubber can be produced by a known solution polymerization method using, for example, stannic (IV) chloride, an organoaluminum / water complex, boron fluoride / ether complex or the like as a catalyst.
The manufacturing method is not limited to this.

The amount of the liquid epichlorohydrin rubber to be added to the fluororubber varies depending on the hardness required for the vulcanized rubber article, but is usually 3 to 100 parts by weight per 100 parts by weight of the fluororubber.
The amount is 150 parts by weight, and if it is less than 3 parts by weight, it is difficult to obtain a vulcanized rubber article having a low hardness, and if it exceeds 150 parts by weight, the compression set becomes undesirably large. Preferably it is 5 to 100 parts by weight.

The fluororubber composition of the present invention can be obtained by kneading the above-mentioned components using a conventional mixer such as a roll, a Banbury or a kneader. At the time of kneading, if necessary, in addition to the above, a necessary amount of a reinforcing agent such as carbon black and silica, a filler such as calcium carbonate, an antioxidant, and a processing aid can be appropriately added.

[0018]

Next, the present invention will be described more specifically with reference to examples and comparative examples. Parts and% in the following are by weight unless otherwise specified.

Example 1 Binary fluororubber (AUSIMONT) was used as the fluororubber.
TECHNOFLON FOR 70BI and NMLB)
Liquid epichlorohydrin rubber (HYD manufactured by Goodrich)
RIN10) and the like were kneaded using a 6-inch roll according to the compounding recipe shown in Table 1 to prepare a rubber composition. Using the obtained rubber composition, test pieces for hardness measurement and compression set measurement were prepared according to JIS K6301.
As for vulcanization conditions, first-stage vulcanization was performed at 180 ° C. for 10 minutes, and then post-vulcanization (secondary vulcanization) was performed at 150 ° C. for 24 hours. The hardness is a value after 10 seconds of contact with the measuring instrument according to JIS K6301, and the compression set is 70
The measurement was performed under conditions of 70 ° C. and a compressibility of 25% at 70 ° C. Also,
The weight change after post vulcanization was measured. Table 1 shows the above results.
Shown in

[0020]

[Table 1]

(Note) (1) Fluoro rubber manufactured by AUSIMONT (2) Fluoro rubber manufactured by AUSIMONT (3) Vulcanized system (polyol system) manufactured by AUSIMONT (4) Carbon black: manufactured by Showa Cabot (5) Magnesium oxide : Kyowa Magnesium Industrial Co., Ltd. (6) Omi Chemical Co., Ltd. (7) Liquid epichlorohydrin polymer: Goodrich Co., Ltd. Hydrin10 (8) Dibutyl phthalate: Daihachi Chemical Co., Ltd.

From the results shown in Table 1, the hardness of the fluororubber composition of the present invention (Examples 1 and 2) is significantly higher than that of Comparative Examples 2 and 3 in which DBP which is a conventional plasticizer is blended. Although reduced, the balance of mechanical properties such as tensile strength is good. Further, in each of the examples, the compression set was improved as compared with Comparative Example 1 in which the amount of carbon black was reduced without blending the plasticizer.

Further, in Examples 1 and 2, 150 ° C. × 24
The hardness after time secondary vulcanization is substantially the same as the hardness after primary vulcanization, and the value of the weight change is small, indicating that the liquid epichlorohydrin polymer is not volatilized. On the other hand, in Comparative Examples 2 and 3 in which the plasticizer DBP was blended, the change in hardness was large, and it was found that DBP was volatilized.

[0024]

As described above, according to the present invention, there is provided a fluororubber composition capable of producing a vulcanized fluororubber product having a low hardness and not contaminating peripheral devices due to volatilization of a plasticizer. Can be provided. The fluororubber composition of the present invention is particularly suitable for production of sealing materials and roll materials for OA equipment.

Claims (4)

[Claims] 1. A fluorine rubber composition comprising a fluorine rubber and a vulcanizing agent and a liquid epichlorohydrin rubber. 2. The fluororubber composition according to claim 1, wherein 3 to 150 parts by weight of liquid epichlorohydrin rubber is blended with respect to 100 parts by weight of fluororubber. 3. A vulcanized fluoro rubber article obtained by vulcanizing the fluoro rubber composition according to claim 1. 4. The vulcanized fluoro rubber article according to claim 3, wherein the rubber article is a sealing material or a roll for OA equipment.