JPH0684454B2 - Vulcanized rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention provides a vulcanized rubber composition having excellent gasoline resistance, gasohol resistance, sour gasoline resistance, sour gasohol resistance, and excellent heat resistance. Regarding

b. Conventional technology In recent years, the atmosphere in which parts made of gasoline-resistant rubber are used in automobiles has tended to become even hotter as a result of measures such as exhaust emission control measures and improvements in engines for the purpose of improving performance. Therefore, gasoline (oil) resistant rubber having excellent heat resistance and ozone resistance is required. Further, it means sour gasoline (gasoline containing peroxide generated by oxidizing gasoline by oxidizing the gasoline.
For more information, see A. Nersasian: Rubber and Plastics News June 26.
(Described in (1978)), which causes a problem of degrading rubber.

Further, due to the worldwide tight demand and supply of crude oil, it has been attempted to mix alcohol with gasoline. This alcohol-blended gasoline (gasohol) also has a problem that it is oxidized like normal gasoline to generate sour gasohol and deteriorate rubber.

c. Problems to be Solved by the Invention Conventionally, butadiene-acrylonitrile rubber has been widely used as a gasoline resistant rubber for applications such as hoses, gaskets, O-rings, packings and oil seals.

However, butadiene-acrylonitrile rubber is
Since the ozone resistance is poor and the heat resistance and sour gasoline resistance are also insufficient, it is difficult to obtain a rubber component having sufficient reliability in the environment where it comes into contact with gasoline at high temperatures as described above.

As a method of improving this, it is known to improve the sour gasoline resistance and ozone resistance by using a blend of butadiene-acrylonitrile rubber and polyvinyl chloride (JP-A-55- 89338), which does not improve the heat resistance, and furthermore, the gasohol resistance is not sufficient.

Conventionally, acrylic rubber has been used as a material excellent in oil resistance, heat resistance, and ozone resistance.
Since it is inferior in gasoline resistance, gasohol resistance and sour gasoline resistance, it is not suitable as a material for engine peripheral parts of automobiles which has recently been demanded, and its improvement is required.

For example, as such an improving means, a rubber composition composed of a mixture of an acrylic rubber and a vinylidene fluoride rubber has been proposed, but in such a composition, gasoline resistance, gasohol resistance, sour gasoline resistance The improvement effect is small.

d. Means for solving the problem The present inventors have conducted extensive studies to obtain a rubber material having excellent gas resistance, gasohol resistance, sour gasoline resistance, sour gasohol resistance, and heat resistance. A vulcanized rubber composition comprising a mixture of at least two groups of rubber selected from acrylic rubber, fluororubber and conjugated diene-α, β unsaturated nitrile rubber and a specific vinylidene fluoride resin has heat resistance, It has been found that not only is it excellent in gasoline resistance and sour gasoline resistance, but it is also excellent in gasohol resistance and sour gasohol resistance, and also has good tensile strength, elongation and balance between gasoline resistance and cold resistance. The invention has been reached.

That is, according to the present invention, at least two groups of rubber (I) selected from the group consisting of acrylic rubber, fluororubber and conjugated diene-α, β-unsaturated nitrile rubber, and vinylidene fluoride are used as constituent components. A vulcanized rubber composition containing at least mol% of vinylidene fluoride resin (II) and a rubber (I) / vinylidene fluoride resin (II) weight ratio of 95/5 to 40/60. Regarding things.

As the acrylic rubber, (A) acrylic acid alkyl ester and / or acrylic acid alkoxy-substituted alkyl ester compound 30 to 99.9% by weight, (B) crosslinkable monomer 0.1 to 10% by weight, and (C) the above (A), Other ethylenically unsaturated compound copolymerizable with (B) 0 to 70% by weight
(However, a multi-component copolymer rubber having a polymerization composition of (A) + (B) + (C) = 100% by weight) can be used. Specifically, the acrylic rubbers described in JP-A-61-136544 and JP-A-61-176652 can be used.

As the fluororubber, tetrafluoroethylene-propylene-based copolymer, vinylidene fluoride-hexafluoropropylene-based copolymer, vinylidene fluoride-chlorotrifluoroethylene-based copolymer, vinylidene fluoride-pentafluoropropylene-based copolymer Combined, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, tetrafluoroethylene-vinylidene fluoride-
Propylene-based copolymer, tetrafluoroethylene-ethylene-isobutylene-based copolymer, ethylene-hexafluoropropylene-based copolymer, tetrafluoroethylene-
Examples thereof include butene-1 type copolymers, tetrafluoroethylene-ethyl vinyl ether type copolymers, tetrafluoroethylene-fluoro vinyl ether type copolymers and the like.

Examples of the conjugated diene-α, β unsaturated nitrile rubber (hereinafter referred to as nitrile rubber) include (D) α, β-unsaturated nitrile 10 to
60% by weight, (E) conjugated diene 15-90% by weight and (F)
Use is made of a multi-component copolymer rubber having a polymerization composition of 0 to 75% by weight (where D + E + F = 100% by weight) of another ethylenically unsaturated compound copolymerizable with the components (D) and (E), and its hydride. it can.

Specific examples of the α, β-unsaturated nitrile of the component (D) include acrylonitrile, α-chloroacrylonitrile,
α-fluoroacrylonitrile, methacrylonitrile,
Although there are ethacrylonitrile and the like, acrylonitrile is particularly preferable among them.

As the conjugated diene as the component (E), butadiene-1,
There are 3,2-chlorobutadiene-1,3, 2-methylbutadiene-1,3, etc., but among them, butadiene-1,3
Is preferred.

As the component (F), various compounds can be used if necessary, and examples thereof include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate. , Acrylic acid alkyl esters such as isoamyl acrylate, n-hexyl acrylate, 2-methylpentyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, n-dodecyl acrylate, n-octadecyl acrylate are preferably used. It

The nitrile rubber can be produced by emulsion polymerization using an ordinary radical polymerization catalyst.

The hydride of the nitrile rubber has a hydrogenation degree of the conjugated diene unit portion in the polymer chain of 10% or more, preferably 30.
% Or more, particularly preferably 50% or more.

The hydride is produced by emulsion polymerization or solution polymerization. Nitrile rubber can be prepared by a conventional method (for example, JP-A-45-3927).
5, the method described in JP-A-50-71681, British Patent 2070023, etc.) is used to hydrogenate the conjugated diene unit portion in the rubber.

Next, the vinylidene fluoride resin (II) used in the present invention
Is polyvinylidene fluoride and vinylidene fluoride and hexafluoropropene, pentafluoropropene, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, vinyl fluoride, perfluoro (methyl vinyl ether), perfluoro (propyl vinyl ether), acetic acid It is a copolymer of one or more kinds of vinyl, ethylene, propylene, butadiene, styrene, acrylic acid ester and the like, and the vinylidene fluoride content is 90 mol% or more, preferably 95 mol% or more. A vinylidene fluoride resin having a vinylidene fluoride content of less than 90 mol% is not preferable in terms of gasoline resistance, gasohol resistance, sour gasoline resistance and sour gasohol resistance. The vinylidene fluoride resin is not particularly limited, but one having a polymerization degree of 100 to 100,000 is preferably used.

Thus, the vulcanized rubber composition of the present invention comprises at least two groups of rubber (I) selected from the group consisting of acrylic rubber, fluororubber and nitrile rubber, and vinylidene fluoride resin (I).
I) is contained, but the ratio of the two is such that the weight ratio of the rubber (I) and the vinylidene fluoride resin (II) is 95 / 5-
It is 40/60. That is, vinylidene fluoride resin (II)
The amount of rubber used is rubber (I) and vinylidene fluoride resin (II)
At least 5 parts by weight in 100 parts by weight of the mixture with
If it is less than 5 parts by weight, the effect of improving gasohol resistance, heat resistance and sour gasoline resistance is not observed, and it is preferably 10 parts by weight or more. As the amount of vinylidene fluoride resin (II) in the mixture increases, the processability deteriorates and the cost increases, so the upper limit of the amount used is naturally determined, usually 60
It is not more than 50 parts by weight, preferably not more than 50 parts by weight. It is particularly preferably 40 parts by weight or less.

The usage ratio of the rubber (I) and the vinylidene fluoride resin (II) in the composition of the present invention can be appropriately determined within the above range depending on the purpose of use and required performance.

The method of mixing the composition of the present invention is not particularly limited, but the following method can be used, for example.

(A) A method of mixing at least two groups of rubber selected from the group of acrylic rubber, fluororubber and nitrile rubber and vinylidene fluoride resin using a mixer such as roll, Banbury mixer, intermixer, etc. ) A method in which at least two groups of rubber selected from the group of acrylic rubber, fluororubber and nitrile rubber and vinylidene fluoride resin are mixed in a latex or suspension form, and then coagulated to coprecipitate, or (C) A method in which (a) and (b) are used in combination, (d) rubber (I) is mixed with carbon black in advance, and vinylidene fluoride resin (II) is heated at a high temperature, specifically 150 Up to 250 ° C, preferably 150 to 200 ° C. If the mixing temperature exceeds 250 ° C, the rubber is deteriorated, which is not preferable. The cross-linking agent is added after cooling the blend.

The rubber composition of the present invention is blended with usual compounding agents such as a reinforcing agent, a filler, a plasticizer, a release agent, a softening agent and a stabilizer. Among them, as the plasticizer, phthalic acid derivative compounds such as diethyl phthalate, di- (2-ethylhexyl) phthalate, dibutyl phthalate, di-n-octyl phthalate and dimethyl cyclohexyl phthalate,
Isophthalic acid derivative compounds such as diisooctylisophthalate, tetrahydrophthalic acid derivative compounds such as di- (2-ethylhexyl) tetrahydrophthalate, di- (2-ethylhexyl) adipate, di- (butoxyethoxyethyl) adipate, butyl Adipic acid derivative compounds such as diglycol adipate, di- (2-
Azelaic acid derivative compounds such as ethylhexyl) azelate, di- (2-ethylhexyl) sepacate, di-
Sepasic acid derivative compounds such as n-butyl sepacate,
Fatty acid derivative compounds such as diethylene glycol monolaurate, tributoxyethyl phosphate, tri-
In addition to phosphoric acid derivative compounds such as (2-ethylhexyl) phosphate and triphenyl phosphate, glycol derivative compounds such as di-butylmethylenebisthioglycolate, glycerin derivative compounds and epoxy derivative compounds, polyester compounds as polymerization plasticizers , Polyether compounds, polyether / ester compounds and the like. Of these, adipic acid derivative compounds,
Phosphoric acid derivative compounds, polyester compounds of polymerization plasticizers, polyether compounds and polyether ester compounds are preferred.

These additives can be mixed with the rubber (I) in advance and then mixed with the vinylidene fluoride resin by the above method,
Alternatively, the rubber (I) and the vinylidene fluoride resin may be mixed and then mixed.

The vulcanized rubber composition of the present invention can be easily obtained as a crosslinked product by a usual crosslinking method.

The vulcanized rubber composition of the present invention is excellent in gasoline resistance, sour gasoline resistance, and heat resistance, and is also excellent in new required performance gasohol resistance and sour gasohol resistance, and also has good tensile strength and elongation. , Because it has cold resistance,
Various hoses that come into contact with fuel oil, hydraulic oil, lubricating oil, etc., including automobile fuel system hoses, various sealing agents such as diaphragms, gaskets, O-rings, oil seals, iron making, spinning, printing Various rolls or transmission belts, conveyor belts, timing belts that require oil resistance and solvent resistance for printing, papermaking, dyeing, etc.
It can be used for chain tensioners, oil dampers, etc.

In particular, it can be suitably used as a rubber for a fuel system hose of an automobile by taking advantage of its excellent sour gasoline resistance and sour gasohol resistance.

e. Examples Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Examples 1-5 and Comparative Examples 1-2 At least two groups of rubber (I) selected from the group of acrylic rubber, fluororubber and nitrile rubber shown in Table-2.
For each sample of the composition of polyvinylidene fluoride and polyvinylidene fluoride (hereinafter referred to as “PVDF”), according to the formulation shown in Table-I,
Blending was performed with a Banbury mixer. The obtained blend was press-cured according to the conditions shown in the lower part of Table-1.

The properties of the obtained crosslinked rubber were measured according to JIS K6301. In addition, sour gasoline resistance and sour gasohol resistance were evaluated by the following methods.

Sour gasoline resistance 2.5 g of lauroyl peroxide dissolved in 97.5 g of Fuel C (mixed solvent of isooctane: toluene = 1: 1 (volume ratio)) was dipped into a test piece at 40 ° C for 72 hours. A test piece was taken out for each cycle in a cycle. 100 ° C
After vacuum drying for 15 hours, bend the test piece 180 degrees,
The state of crack generation was observed.

Sour gasohol resistance It was evaluated in the same manner as the sour gasoline resistance evaluation method, except that a mixed solvent of Fuel C and ethanol (volume ratio Fuel C: ethanol = 80: 20) was used instead of Fuel C.

The evaluation results are shown in Table-3.

From the results of Table-3, the vulcanized rubber composition of the present invention has excellent gasoline resistance, gasohol resistance, sour gasoline resistance, sour gasohol resistance, heat resistance, and further tensile strength,
It can be seen that it is possible to provide a vulcanized rubber composition having an excellent balance of elongation, gasoline resistance and cold resistance. f. Effects of the Invention The vulcanized rubber composition of the present invention is excellent in gasoline resistance, sour gasoline resistance, gasohol resistance, sour gasohol resistance, heat resistance, and further tensile strength, elongation, gasoline resistance-cold resistance. A vulcanized rubber composition having an excellent balance of properties.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Nobu 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Nippon Synthetic Rubber Co., Ltd. (56) Reference JP-A-57-135844 (JP, A) 52-60839 (JP, A)

Claims (1)

[Claims] 1. A rubber (I) of at least two groups selected from the group of acrylic rubbers, fluororubbers and conjugated diene-α, β-unsaturated nitrile rubbers, and 90 mol of a constituent component consisting of vinylidene fluoride. % Or more vinylidene fluoride resin (II), and the rubber (I) / vinylidene fluoride resin (II) weight ratio is 95/5 to 40/60. .