JPH02245046A - Rubber composition - Google Patents

Abstract

PURPOSE:To obtain a rubber composition which can give a vulcanizate improved in heat resistance, oil resistance and abrasion resistance by mixing a mixture of a specified fluororubber with an acrylic rubber with an organic peroxide and a trialkenyl trimellitate. CONSTITUTION:A mixture (A) is obtained by mixing 10-50wt.% fluororubber having reactive bromo and/or iodo groups in the molecule with 90-50wt.% acryl ic rubber (e.g. ethyl acrylate/n-butyl acrylate/acryl acrylate terpolymer). 100 pts.wt. component A is mixed with 0.1-10 pts.wt. organic peroxide (B) [e.g. 1,3-di(tert-butyl peroxyisopropyl)benzene], 0.5-20 pts.wt. trialkenyl trimellitate (C) (e.g. triallyl trimellitate) and optionally a reinforcing agent, a filler, a processing aid, etc., (D), and the obtained mixture is kneaded under heating at 150 deg.C for 5-60min to crosslink component A with component B in the presence of component C and optionally subjected to secondary vulcanization at 120-200 deg.C for 5-24hr.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rubber composition. More specifically, it relates to a rubber composition whose main component is a blended rubber of fluororubber and acrylic rubber.

[Conventional technology]

Acrylic rubber has superior heat and oil resistance compared to single-layer rubbers such as NBR and chloroprene rubber, and is used as a molding material for oil seals, O-rings, packings, hoses, etc. However, its operating temperature is at most 1
The temperature is approximately 50°C, and fluororubber is used when even higher heat resistance and oil resistance are required. Acrylic rubber also has poor abrasion resistance.

On the other hand, although fluororubber has very excellent properties in terms of heat resistance, oil resistance, and abrasion resistance, it has the disadvantage of high cost. Another problem is that oil additives in engine oil, hydraulic oil, etc. cause rapid deterioration.

Furthermore, for the purpose of improving cold resistance, it is described in JP-A-63-41930 that trimellitic acid trialkenyl ester is used as a co-crosslinking agent for peroxide-crosslinkable fluororubber; As can be seen from the results of Example 2, rapid deterioration of fluororubber due to oil additives (engine oil, hydraulic oil, etc.) cannot be prevented.

[Problem to be solved by the invention]

An object of the present invention is to provide a rubber material that has the characteristics of both fluororubber and acrylic rubber, that is, a rubber composition that provides a vulcanizate with excellent heat resistance, oil resistance (additive resistance), and abrasion resistance. It's about doing.

[Means to solve the problem]

The object of the present invention is to contain reactive bromine groups and/or
Alternatively, this can be achieved by a rubber composition in which an organic peroxide and a trialkenyl trimellitate ester are blended with a blend rubber of a fluororubber having an iodine group and an acrylic rubber.

The fluororubber is prepared by homopolymerizing or copolymerizing a fluorine-containing olefin having 2 to 8 carbon atoms, such as vinylidene fluoride, tetrafluoroethylene, hexafluoropropene, etc., preferably by polymerizing vinylidene fluoride with at least one other fluorine-containing olefin. When copolymerizing with an elementary olefin, it is obtained by carrying out a polymerization reaction in the coexistence of various halogen-containing organic compounds.

Examples of the halogen-containing organic compound used include the following.

・RfIx (Japanese Unexamined Patent Publication No. 53-1.25,491)
Rf: Fluorohydrocarbon group, chlorofluorohydrocarbon group・RI□~2 (Patent No. 60-221,409) R: Hydrocarbon group having 1 to 3 carbon atoms・RBrx (Patent No. 59-20,310) R: Saturated aliphatic hydrocarbon group/brominated olefin (Japanese Patent Publication No. 54-1585) bromotrifluoroethylene, 4-bromo-3,3,4,
4-Tetrafluorobutene-1 etc.-ROCX=CYZ (JP-A-1986-1.95,113
(No. Publication) Aromatic compounds or perfluoroaromatic compounds containing either bromine or iodine that are polysubstituted by a bromine atom or alkyl bromide group, or an iodine atom or an alkyl iodide group (Ibid. 62-232, 407)
No. 63-23,907) - Iodine and/or bromine-containing organic peroxide compound (No. 63-23,907) - RBrnl,
(No. 63-308,008) R: fluorohydrocarbon group, chlorofluorohydrocarbon group, chlorohydrocarbon group, hydrocarbon group n, m: 1 or 2 A part of these reactive halogen group-containing fluororubbers are commercially available, and for example, DuPont's VTR5927, Daikin's G-901, 0-902, etc. can be used as they are.

The acrylic rubber may be at least one selected from the group consisting of alkyl acrylates in which the alkyl group has 1 to 8 carbon atoms, and alkoxyalkyl acrylates in which the alkyl group and the alkylene group each have 1 to 4 carbon atoms. It is a polymer of one type of acrylate, and a polymerizable monomer and/or a crosslinkable group-containing monomer that can be copolymerized with these monomers may be copolymerized therein. A few examples of such acrylate polymers are as follows: Ethyl acrylate-n-butyl acrylate-methoxyethyl acrylate ternary copolymer Ethyl acrylate-n-butyl acrylate-allyl acrylate ternary copolymer Combined n-butyl acrylate-methoxyethyl acrylate-2-hydroxyethyl acrylate ternary copolymer Ethyl acrylate-n-butyl acrylate-2-carboxyethyl acrylate ternary copolymer n-butyl acrylate-methoxyethyl acrylate-allyl acrylate 3 Original copolymer n-butyl acrylate-methoxyethyl acrylate copolymer ethyl acrylate-hydroxyalkyl acrylate copolymer polyethyl acrylate Reactive halogen group-containing fluororubber and acrylic rubber
Generally the former is about 10-50% by weight2, preferably about 20-50% by weight2
The latter is used in a blend of about 10 to 50 parts by weight, preferably about 80 to 60 parts by weight. If the latter is used in a proportion greater than this, heat resistance and oil resistance, especially abrasion resistance, will be significantly inferior. On the other hand, if the latter is used in a proportion lower than this, rapid deterioration of the fluororubber due to the oil additive cannot be prevented.

Both of these blended rubbers are co-crosslinked with an organic peroxide in the presence of a trimellitic acid trialkenyl ester. The alkenyl groups forming the triester group of trimellitic acid are represented by the formulas -(CL)1 to GCH=CH2, and the triester groups may be the same or different alkenyl groups. Specific compounds include, for example, triallyl trimellitate, 1,4-diallyl-2-butenyl trimellitate, and 1,2-diallyl-4-butenyl trimellitate.

Tributenyl trimellitate, 1-butenyl-2,4-
Examples include diallyl trimellitate, tripentenyl trimellitate, 1,2-diallyl-4-pentenyl trimellitate, and the like. These are generally blended rubbers with 10
About 0.5 to 20 parts by weight per 0 parts by weight, preferably about 2 to 20 parts by weight
It is used in a proportion of 10 parts by weight.

In addition, examples of organic peroxides include di-tert-butyl peroxide, dicumyl peroxide, di-tert-butylcumyl peroxide, 1,1-di(tert-butyl peroxy)-
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-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(benzoyl) (peroxy)hexane, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, n-butyl-4,4-di(tert-butyl peroxy) valerate, etc., are generally used in the blend rubber 1.
About 0.1 to 10 parts by weight per 00 parts by weight, preferably about 0
．． It is used in a proportion of 5 to 8 parts by weight.

If the proportion of trimellitic acid trialkenyl ester or organic peroxide used is less than this, the crosslinking density will be so low that vulcanization molding will not be possible, or even if vulcanization molding is possible, the rubber strength will be below practical strength. Only vulcanized products with a certain amount can be obtained, whereas if a higher proportion is used,
Molding problems such as reversion and foaming will occur.

In addition to the above essential ingredients, reinforcing agents such as carbon black and fine silica, fillers such as talc, clay, graphite, and calcium silicate, stearic acid,
Compounding agents commonly used in the rubber industry, such as processing aids such as palmitic acid and paraffin wax, acid acceptors such as zinc oxide, antiaging agents, and plasticizers, can be appropriately added.

The rubber composition is prepared by kneading it using a mixing machine such as an intermix, a kneader, or a Banbury mixer, or an oven roll, and the vulcanization thereof is carried out by
This is generally done by heating at about 150 to 200°C for about 5 to 60 minutes using an injection molding machine, compression molding machine, vulcanization press, etc., and if necessary, heating at about 120 to 200°C for about 5 to 60 minutes.
A 24 hour secondary vulcanization is carried out.

〔Effect of the invention〕

What are reactive halogen group-containing fluororubber and acrylic rubber?
When blended, there is no problem in compatibility, and -8 = mixing is possible without causing microscopic interfacial peeling.

By co-crosslinking such a blended rubber with an organic peroxide in the presence of trialkenyl trimellitate, properties that cannot be obtained with each rubber alone, namely heat resistance, oil resistance, and abrasion resistance, are achieved in a well-balanced manner. A rubber composition is provided which can provide a vulcanizate with the following properties.

Therefore, the rubber composition of the present invention can be suitably used as a rubber material for seals such as oil seals, packings, O-rings, D-rings, and diaphragms, or as molding materials for industrial rubber materials such as hoses, belts, and rubber rolls. I can do it.

〔Example〕

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

Examples 1 to 3, Comparative Examples 1 to 4 IQ
After kneading in a kneader, heat press molding is performed at 170°C for 20 minutes in a heat press, and then heated at 175°C in a heating oven.
, 15 hours of oven vulcanization, 150X 150
A vulcanized rubber sheet with a diameter of 2 mm was molded.

Table 1 Acrylic rubber I Acrylic rubber ■ Acid im ■ Square - Bomb black Stearic acid paraffin wax Diphenylamine triallyl trimellitate 1.4-Dialino L/-2-butenyl trimellitate N, N'-y-phenylenedi Maleimide 10.5 Vulcanized rubber seams obtained in the above examples and comparative examples 1
- For hardness, an air heating aging test and an oil resistance test were conducted in accordance with JIS K-6301.

Tensile strength, elongation, their rate of change, and volume change rate (oil resistance test only) were measured.

In addition, we conducted a taper wear test (1 (18, load IKgf, 1000 times) in accordance with JIS K-7204,
The amount of wear was measured. The results obtained are shown in Table 2 below.

Note that the vulcanized rubber sheet obtained in Comparative Example 3 had a tensile strength of only 20 kgf/dL and did not have a practical function as a vulcanized rubber.

(Leaving space below) Acrylic rubber ■: Ethyl acrylate methoxyethyl Table 2 has poor abrasion resistance, and Comparative Example 2 has fine cracks and racks on the surface of the vulcanized rubber sheet after the oil resistance test. Admitted. Furthermore, the amount of wear in Comparative Example 4 was greater than that in Comparative Example 1.

Claims (1)

[Claims] 1. A rubber composition prepared by blending an organic peroxide and a trialkenyl trimellitate with a blend rubber of acrylic rubber and a fluororubber having a reactive bromine group and/or iodine group in the molecule.