JPH07179704A - Fluororubber composition - Google Patents

Abstract

PURPOSE:To obtain a fluororubber composition comprising a fluororubber consisting of a copolymer produced mainly from vinylidene fluoride, an organic peroxide, a divalent metal hydroxide, an organic base, a phenolic compound, etc., capable of being inexpensively and easily vulcanized, and good in storage stability. CONSTITUTION:This fluororubber composition capable of being inexpensively and easily vulcanized and good in storage stability comprises (A) a fluororubber obtained by copolymerizing vinylidene fluoride with at least one of copolymerizable ethylenic unsaturated monomers (e.g. tetrafluoroethylene), (B) an organic peroxide (e.g. 2,5-dimethyl-2,5-di-t-butylperoxyhexane), (C) at least one of a divalent metal hydroxide, a divalent metal oxide, etc., (D) an organic base (e.g. tetrabutylammonium bisulfate), and (E) at least one of a phenolic compound (e.g. p-methoxyphenol), an aromatic amine compound (e.g. p- phenylenediamine), etc.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fluororubber composition for the purpose of vulcanizing an organic peroxide.

[0002]

In the vulcanization of fluororubber with organic peroxide, unsaturated polyfunctional compounds such as triallyl isocyanurate, divalent metal hydroxides such as calcium hydroxide,
The method using an organic base such as a salt derived from diazabicycloundecene is a fluororubber obtained by copolymerizing an expensive monomer containing iodine or bromine, or a fluororubber subjected to alkali treatment in the presence of an onium salt. It is known as a method that can be vulcanized easily at a low cost as compared with the method using [JP-A-1-198654].

[0003]

The method of blending the above-mentioned unsaturated polyfunctional compound, divalent metal hydroxide, and organic base has a special vulcanization site for organic peroxide vulcanization. It is an excellent method that does not require fluororubber,
There was a problem of storage stability that the fluorinated rubber blend was gradually vulcanized at room temperature during storage before the actual vulcanization step.

[0004]

The present invention has been made to solve the above-mentioned problems, and (A) vinylidene fluoride and at least one ethylenically unsaturated monomer copolymerizable therewith. Fluorine rubber obtained by copolymerizing the body,
At least one selected from the group consisting of (B) organic peroxide, (C) divalent metal hydroxide and divalent metal oxide.
Species, (D) organic base, and (E) at least one selected from phenolic compounds and aromatic amine compounds
The present invention provides a fluororubber composition comprising a seed.

The fluororubber of component (A) used in the present invention is a copolymer comprising vinylidene fluoride and at least one ethylenically unsaturated monomer copolymerizable therewith. As the ethylenically unsaturated monomer, hexafluoropropylene, pentafluoropropylene, propylene, trifluoroethylene, tetrafluoroethylene,
Examples include perfluoro- (alkyl vinyl ethers) such as chlorotrifluoroethylene, ethylene, vinyl fluoride, perfluoro- (methyl vinyl ether), and perfluoro- (hexyl vinyl ether).

Of these, vinylidene fluoride-tetrafluoroethylene-propylene copolymers, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymers, and vinylidene fluoride-hexafluoropropylene copolymers are preferably used. To be done. Here, the copolymerization ratio of vinylidene fluoride is appropriately selected depending on the desired physical properties, the type of ethylenically unsaturated monomer to be copolymerized, etc., but usually 0.1 to 90 mol% is adopted. .
A vinylidene fluoride-tetrafluoroethylene-propylene-based copolymer is preferable because a vulcanized fluororubber excellent in engine oil resistance can be obtained. In particular, a ternary copolymer containing 0.1 to 70 mol% of vinylidene fluoride polymer units, 20 to 60 mol% of tetrafluoroethylene polymer units and 10 to 50 mol% of propylene polymer units is added. The fluorinated fluororubber is preferably used because it has excellent balance of engine oil resistance, vulcanization characteristics, and vulcanization physical properties.

Further, according to the composition of the present invention, a vulcanizate having good vulcanization properties and excellent physical properties even if the easily vulcanizable site is not introduced into the fluororubber of component (A). Can be obtained. Here, the easily vulcanizable site includes bromine, iodine, and a double bond introduced into the polymer chain, and examples thereof include a method of copolymerizing a monomer such as an iodine compound and a bromine compound, or a double bond. It can be introduced by a heat treatment for imparting an alkali or an alkali treatment in the presence of onium salt.

Various polymerization methods such as bulk polymerization, suspension polymerization, emulsion polymerization and solution polymerization can be adopted for the production of the fluororubber of the component (A), and a catalytic polymerization method using a free radical initiator, ionization Radiation polymerization method, redox polymerization method and the like can be appropriately adopted.

The component (B) organic peroxide used in the present invention is an organic compound having a --O--O-- bond used as a vulcanizing agent, and includes peroxyketal, dialkyl peroxide, diacyl peroxide, Peroxyester, hydroperoxide, etc. are adopted. Specific examples thereof include benzoyl peroxide,
Dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di- (t-butylperoxy) -hexane, 2,5-dimethyl-2,5-di-
(T-Butylperoxy) -hexyne-3, α, α'-
Bis- (t-butylperoxy) -p-diisopropylbenzene, 1,1-bis- (t-butylperoxy)-
3,3,5-trimethylcyclohexane and the like can be mentioned. Of these, α, α′-bis- (t-butylperoxy) -p-diisopropylbenzene and 2,5-dimethyl-2,5-di- (t-butylperoxy) -hexane can be preferably used. The amount of these organic peroxides used is in the range of 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of fluororubber.

In the composition of the present invention, at least one selected from the group consisting of the divalent metal hydroxide and the divalent metal oxide of the component (C) and the organic base of the component (D) are blended. Therefore, the vulcanization reaction is accelerated.

Component (C) is a divalent metal hydroxide or 2
Valuable metal oxides include magnesium, calcium,
There may be mentioned hydroxides or oxides of lead, zinc and the like. The amount of these metal hydroxides and metal oxides used is in the range of 1 to 20 parts by weight, preferably 2 to 10 parts by weight, per 100 parts by weight of the fluororubber. However, it can be used more than that.

As the organic base of the component (D), tetrabutylammonium bromide, tetrabutylammonium hydrogen sulfate, trioctylmethylammonium hydrogen sulfate, 8-benzyl- (5,4,0) -diazabicycloundecenium chloride is used. , P-toluenesulfonic acid,
(5,4,0) -diazabicycloundecenium, tetrabutylphosphonium chloride, tetrabutylphosphonium bromide, tributyl- (methoxypropyl)
-Organonium compounds such as phosphonium chloride, benzyltrioctylphosphonium chloride and benzyltriphenylphosphonium chloride, triethylamine, pyridine, (5,4,0) -diazabicycloundecene, triphenylphosphine, tributylphosphine, triphenylphosphite And nitrogen- or phosphorus-containing compounds such as These may be used alone or as a mixture of two or more. The amount of these organic bases used is usually 0.1 to 5 parts by weight, preferably 0.3 to 3 parts by weight, based on 100 parts by weight of the fluororubber. 0.
If it is less than 1 part by weight, sufficient vulcanization density and vulcanized physical properties cannot be obtained, and if it exceeds 5 parts by weight, moldability such as scorch phenomenon is adversely affected and properties of vulcanized product such as chemical resistance are deteriorated. Let

The phenolic compound or aromatic amine compound as the component (E) serves as a storage stabilizer of the composition of the present invention at room temperature and a vulcanization retarder during vulcanization.

As the phenolic compound, phenol, cresol, p-methoxyphenol, 3-methyl-4-isopropylphenol, tributyl-p-phenylphenol, allylphenol and the like are preferably used.

As the aromatic amine compound, aniline and its derivative, paraphenylenediamine and its derivative, naphthylamine and its derivative, diphenylamine and its derivative and the like are preferably used.

The amount of these phenolic compounds or aromatic amine compounds used is usually in the range of 0.05 to 5 parts by weight with respect to 100 parts by weight of the fluororubber.

The composition of the present invention comprises a vulcanization of carbon black, fine silica, clay, talc and other reinforcing agents, triallyl isocyanurate, trimethylolpropane trimethacrylate, etc., which have been conventionally used in the production of vulcanized rubber. Auxiliaries, other fillers, pigments, antioxidants, stabilizers, processing aids, internal release agents and the like may be added and blended. Further, other synthetic rubber, natural rubber, thermoplastic resin, thermosetting resin or the like may be mixed. The fluororubber composition of the present invention can be easily obtained by mixing the above-mentioned respective components with a usual rubber kneading device such as a roll, a kneader, a Banbury mixer, an extruder or the like.

The fluororubber composition thus obtained is vulcanized and molded by a conventional method. The vulcanization conditions vary depending on the molding method and the shape of the molded product, but are generally 100 ° C.
It is several seconds to 5 hours at 400 ° C. Secondary vulcanization may be performed to stabilize the physical properties of the vulcanizate. The secondary vulcanization conditions are 150 ° C to 300 ° C for 30 minutes to 4
It is about 8 hours.

[0019]

In the present invention, the organic peroxide is decomposed by the organic base and the divalent metal hydroxide or oxide, and the radicals generated are trapped by the phenol compound or the aromatic amine compound so that the storage stability is improved. Is estimated to be improved.

[0020]

EXAMPLES In the examples, "parts" means "parts by weight".

Example 1 A fluororubber having a copolymerization ratio of vinylidene fluoride / tetrafluoroethylene / propylene of 35/40/25 (molar ratio) was produced by an emulsion polymerization method. MT carbon 3 to 100 parts of this fluororubber
0 part, 1 part of Perhexa 2,5B (Nippon Oil and Fats Co., Ltd. organic peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane), 3 parts of magnesium oxide, tetrabutylammonium hydrogen sulfate. A fluororubber composition was obtained by uniformly mixing 0.8 parts and 0.2 part of p-methoxyphenol with two rolls. The Mooney viscosity of this fluororubber composition was ML1 + 4 (121 ° C.) = 58.
The Mooney viscosity after storing this fluororubber composition at 25 ° C. for 30 days was ML1 + 4 (121 ° C.) = 60. Also, this fluororubber composition was heated at 170 ° C. for 10
When the physical properties were measured by press vulcanization for 1 minute and secondary vulcanization at 230 ° C. for 24 hours, the hardness was 70 (JIS-A),
100% modulus 5.5 MPa, tensile strength 16.3M
Pa and elongation was 230%.

Example 2 The same procedure as in Example 1 was repeated except that 0.2 part of the aromatic amine compound Naugard 445 (a diphenylamine derivative manufactured by Uniroyal Corporation) was used in place of the phenol compound p-methoxyphenol. A rubber composition was obtained. The Mooney viscosity of this fluororubber composition is ML1 + 4 (121 ° C.) = 60, and the Mooney viscosity after storing at 25 ° C. for 30 days is ML1 + 4 (12).
1 ° C.) = 61. 170% of this fluororubber composition
The physical properties obtained by press vulcanization at 10 ° C for 10 minutes and secondary vulcanization at 230 ° C for 24 hours have a hardness of 72 (JIS-A), 100.
% Modulus 6.1 MPa, tensile strength 15.9 MPa,
The elongation was 220%.

[Example 3] The copolymerization ratio of vinylidene fluoride / hexafluoropropylene was 80 by the emulsion polymerization method.
A / 20 (molar ratio) fluororubber was produced. To 100 parts of this fluororubber, 30 parts of MT carbon, 1 part of Perhexa 2,5B, 3 parts of magnesium oxide, 0.8 part of tetrabutylammonium hydrogensulfate, and 3-methyl-4.
-0.2 parts of isopropylphenol were uniformly mixed with 2 rolls to obtain a fluororubber composition. The Mooney viscosity of this fluororubber composition is ML1 + 4 (121 ° C.) = 51.
Met. In addition, this fluororubber composition was used at 25 ° C for 30
The Mooney viscosity after storage for a day is ML1 + 4 (121
C.) = 52. In addition, this fluororubber composition 1
When the physical properties were measured by press vulcanization at 70 ° C for 10 minutes and secondary vulcanization at 230 ° C for 24 hours, a hardness of 73 (J
IS-A), 100% modulus 5.9 MPa, tensile strength 15.4 MPa, elongation 200%.

[Example 4] In Example 3, 0.2 part of the aromatic amine compound Nocrack White (paraphenylenediamine derivative manufactured by Ouchi Shinko Co., Ltd.) was used in place of the phenol compound 3-methyl-4-isopropylphenol. A rubber composition was obtained in exactly the same manner except that it was used. The Mooney viscosity of this fluororubber composition is ML1 + 4 (121 ° C.) = 50.
The Mooney viscosity after storage at 25 ° C. for 30 days was ML1 + 4 (121 ° C.) = 52. The fluororubber composition was press-vulcanized at 170 ° C. for 10 minutes and secondary-vulcanized at 230 ° C. for 24 hours.
(JIS-A), 100% modulus was 5.7 MPa, tensile strength was 14.6 MPa, and elongation was 200%.

Comparative Example 1 A fluororubber composition was obtained in the same manner as in Example 1 except that p-methoxyphenol was not used. The Mooney viscosity of this fluororubber composition was ML1 + 4 (121 ° C.) = 58. The Mooney viscosity after storing this fluororubber composition at 25 ° C. for 30 days was ML1 + 4 (121 ° C.) = 105. Moreover, when this fluororubber composition was press-vulcanized at 170 ° C. for 10 minutes and secondary-vulcanized at 230 ° C. for 24 hours to measure physical properties, hardness 73 (JIS-A), 100% modulus 6. The tensile strength was 6 MPa, the tensile strength was 16.9 MPa, and the elongation was 200%.

[0026]

INDUSTRIAL APPLICABILITY The present invention provides a fluororubber composition which is inexpensive and can be easily vulcanized with an organic peroxide and has good storage stability, and its industrial advantage is extremely large. . Furthermore, based on various excellent vulcanization properties, radiators for automobiles, O-rings around the engine, gaskets, sealing materials, diaphragms, tubes,
It is extremely useful in a wide range of applications such as hoses and similar parts such as food plants and chemical plants.

Claims (1)

[Claims] 1. A fluororubber obtained by copolymerizing (A) vinylidene fluoride and at least one ethylenically unsaturated monomer copolymerizable therewith, (B) an organic peroxide,
(C) at least one selected from the group consisting of divalent metal hydroxides and divalent metal oxides, (D) organic base,
And (E) a fluororubber composition comprising at least one selected from the group consisting of a phenolic compound and an aromatic amine compound.