JPH06306236A - Fluororubber composition - Google Patents

Abstract

PURPOSE:To obtain the composition useful as an automotive radiator, etc., having excellent mold release characteristics and vulcanizing characteristics, comprising specific fluororubber, a specific metal oxide, etc., an organic peroxide and an amine, etc. CONSTITUTION:The objective composition comprises (A) 100 pts.wt. of fluororubber obtained by copolymerizing vinylidene fluoride with one or more ethylenic unsaturated monomers such as tetrafluoroethylene copolymerizable with it, (B) preferably 1-5 pts.wt. of an organic peroxide such as peroxy ketal, (C) preferably 2-10 pts.wt. of one or more selected from a (hydroxide) oxide of a bivalent metal such as magnesium, (D) preferably 0.05-5 pts.wt. of an organic phosphorus compound such as tertiary phosphine and more preferably (E) preferably 0.5-3 pts.wt. of an organic onium compound such as an organic quaternary ammonium hydrogensulfate.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art When vulcanizing a fluororubber with an organic peroxide, a bromine- or iodine-containing vulcanization site monomer is copolymerized or an organic base is added without using those vulcanization site monomers. Those used as sulfur accelerators are known. Particularly, the latter is an economically excellent method because it does not use a vulcanization site monomer.

However, in the conventional organic peroxide vulcanization of fluororubber, it is substantially necessary to use an unsaturated polyfunctional compound such as triallyl isocyanurate as a vulcanization aid, and therefore fluororubber is used. There is a problem that the mold releasability is inferior to other vulcanization methods such as polyol vulcanization and polyamine vulcanization.

[0004]

The present invention has been made in order to solve the above-mentioned technical problems, and by using an organic phosphorus compound as a vulcanization accelerator, vulcanization can be performed easily and at low cost. Provided is a fluororubber composition capable of being vulcanized with an organic peroxide, which is excellent in mold releasability, without impairing the properties and good properties of the fluororubber.

[0005]

That is, the present invention provides a fluorine obtained by copolymerizing (A) vinylidene fluoride and at least one other ethylenically unsaturated monomer copolymerizable therewith. Provided is a fluororubber composition containing rubber (B) organic peroxide (C) at least one selected from divalent metal hydroxide and divalent metal oxide, and (D) organic phosphorus compound. .

The fluororubber of component (A) used in the present invention is obtained by copolymerizing vinylidene fluoride and at least one ethylenically unsaturated monomer copolymerizable therewith. Thus, as the ethylenically unsaturated monomer copolymerizable with vinylidene fluoride, hexafluoropropylene, pentafluoropropylene, propylene,
Trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, ethylene, vinyl fluoride,
Examples include perfluoro (methyl vinyl ether), perfluoro (hexyl vinyl ether), and other perfluoro (alkyl vinyl ether).

Of these, vinylidene fluoride-tetrafluoroethylene-propylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, and vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer are preferably used.

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 if the ratio of vinylidene fluoride is too small, it will be vulcanized. If the amount of the vulcanizate is insufficient, the properties of the vulcanizate will be impaired, and if the amount is too large, physical properties such as lack of rubber elasticity of the fluororubber and deterioration of alkali resistance will occur. Usually, the vinylidene fluoride unit is 0.5 to 90 mol%, particularly preferably 1 to 8
The one containing 5 mol% is adopted.

Particularly, it is preferable to use a vinylidene fluoride-tetrafluoroethylene-propylene copolymer because a vulcanized fluororubber excellent in engine oil resistance can be obtained. Among them, a vinylidene fluoride-tetrafluoroethylene-propylene ternary system containing 1 to 50 mol% of vinylidene fluoride units, 20 to 60 mol% of tetrafluoroethylene units, and 10 to 50 mol% of propylene units. The copolymer is preferably used because the vulcanized fluororubber has excellent balance in engine oil resistance, vulcanization characteristics, and vulcanization physical properties.

Further, it is preferable to use a vinylidene fluoride-hexafluoropropylene copolymer or a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer because a vulcanized fluororubber excellent in low temperature characteristics can be obtained. Among them, a binary copolymer containing vinylidene fluoride and hexafluoropropylene in a proportion of 50 to 85 mol% and 15 to 50 mol%, vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene in a proportion of 40 to 85, respectively. Mol%, 1
A terpolymer containing 40 mol% and 10 to 50 mol% is preferably used because the vulcanized fluororubber has excellent balance in vulcanization characteristics, vulcanization physical properties and low temperature characteristics.

Further, the fluororubber of the component (A) in the composition of the present invention can obtain good vulcanization characteristics even if the easy vulcanization site usually used for organic peroxide vulcanization is not introduced. A vulcanized product having good physical properties can be obtained, which is economically advantageous.

Here, the easily vulcanized site refers to bromine, iodine or a double bond introduced into the polymer chain. This easily vulcanizable portion is copolymerized with a monomer (for example, iodine compound, bromine compound, etc.) that gives an easily vulcanizable portion, or post-treated to give an easily vulcanizable portion (heat treatment, presence of onium salt). It can be introduced by performing an alkali treatment or the like below.

In the production of the fluororubber of the component (A), various polymerization methods such as bulk polymerization, suspension polymerization, emulsion polymerization and solution polymerization can be adopted, and a catalytic polymerization method using a free radical initiator, An ionizing radiation polymerization method, a redox polymerization method or the like can be appropriately adopted.

The component (B) organic peroxide used in the present invention is used as a vulcanizing agent and is an organic compound having a --O--O-- bond, such as peroxyketal, dialkyl peroxide, diacyl peroxide, Peroxyester, hydroperoxide, etc. are adopted.

Specific examples thereof are 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,
Examples include α, α′-bis (t-butylperoxy) -p-diisopropylbenzene and 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane.

Of these, α, α'-bis (t-butylperoxy) -p-diisopropylbenzene, 2,5
-Dimethyl-2,5-di (t-butylperoxy) hexane can be preferably used. The amount of these organic peroxides used is 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the component (A).

In the composition of the present invention, at least one selected from the divalent metal hydroxide and the divalent metal oxide of the component (C) and the organophosphorus compound of the component (D) are blended. As a result, even if the fluororubber does not have an easily vulcanized site, a vulcanized product having excellent physical properties can be obtained due to the organic peroxide.

Component (C) divalent metal hydroxide or 2
Valuable metal oxides include magnesium, calcium,
Examples include hydroxides and oxides such as lead and zinc. The amounts of these metal hydroxides and oxides used are 10
1 to 20 parts by weight, preferably 2 to 10 parts by weight, are used per 0 parts by weight.

Examples of the organophosphorus compound as the component (D) include phosphine, phosphite, phosphate, phosphine oxide and the like. Specific examples include triphenylphosphine, tributylphosphine, trioctylphosphine, triphenylphosphite and triethylphosphite. Examples thereof include phyto, triphenyl phosphate, tributyl phosphate, triphenylphosphine oxide, trioctylphosphine oxide and the like. Among them, tertiary phosphine is preferably used because it has a great effect of vulcanization. The amount of component (D) used is 0.05 to 5 parts by weight per 100 parts by weight of fluororubber.

In the present invention, the organic onium compound as the component (E) is used in combination with each of the above-mentioned components to further accelerate vulcanization, and includes an organic quaternary ammonium salt, an organic quaternary iminium salt, and an organic 4 A quaternary phosphonium salt or the like is used, and particularly, an organic quaternary ammonium hydrogensulfate or an organic quaternary ammonium p-toluenesulfonate is preferably used.

Examples of these organic onium compounds are tetrabutylammonium hydrogensulfate, tetramethylammonium hydrogensulfate, tetraethylammonium hydrogensulfate,
Trioctylmethylammonium hydrogen sulfate, 1,8-diazabicyclo [5.4.0] -7-undecenium hydrogen sulfate, 1,8-diazabicyclo [5.4.0] -7-undecenium p-toluenesulfonate, tetrabutyl Examples thereof include ammonium bromide, tetrabutylammonium chloride, triphenylbenzylphosphonium chloride, tetrabutylphosphonium chloride, bis (diphenylbenzylphosphine) iminium chloride and the like.

The amount of these organic onium compounds used is usually 0.3 to 5 parts by weight, preferably 0.5 to 3 parts by weight, per 100 parts by weight of fluororubber.

In the fluororubber composition of the present invention, an unsaturated polyfunctional compound can be used as a vulcanization aid as in the conventional organic peroxide vulcanization. In this case, the amount of the unsaturated polyfunctional compound used can be significantly reduced as compared with the conventional one, and therefore the mold releasability is not significantly deteriorated.

Examples of unsaturated polyfunctional compounds include polyallyl compounds, methacrylate compounds, divinyl compounds and polybutadiene. Among them, triallyl isocyanurate, triallyl cyanurate, trimethylolpropane trimethacrylate and the like are preferably used.

The composition of the present invention contains a reinforcing agent such as carbon black, fine silica, clay and talc, which is conventionally used in the production of vulcanized rubber, and other fillers.
Pigments, antioxidants, vulcanization aids, stabilizers, processing aids, internal release agents, etc. may be added and blended.

In producing the composition of the present invention, (A)
It is desirable to sufficiently uniformly mix the components (E) to (E) and, if necessary, other additives. Such mixing can be carried out by using a rubber kneading roll, a kneader, a Banbury mixer or the like which has been conventionally usually used. Working conditions during mixing are not particularly limited, but usually 30 to 80
By kneading at a temperature of about 0 ° C. for about 10 to 60 minutes, the additive composition can be sufficiently dispersed and mixed in the fluorine-containing elastic copolymer.

It is also possible to dissolve and disperse such an additive formulation in a solvent to prepare a suspension solution. Furthermore, so-called wet mixing in which the mixing is carried out in the medium from the beginning is also possible. In such a case, a solution-form compound can be obtained by using a mixer such as a roll, a ball mill and a homogenizer. When the organic onium compound is mixed, it can be more effectively dispersed by mixing it in the state of the aqueous dispersion after the production of the fluororubber. It is desirable that the working conditions and operations during the mixing are performed by selecting the optimum conditions according to the type and purpose of the raw materials used and the compound.

The composition of the present invention can be used in the usual mold forming,
Extrusion, transfer, roll coat, brush coating,
It can be molded into molded products such as sheets, pipes, rods, tubes, angles, channels, draped fabrics, coated plates, etc. by continuous molding processing such as impregnation. It can also be molded into a special molded product such as sponge rubber.
The composition of the present invention thus molded and processed can be made into a vulcanized product by a vulcanizing means as described below. Thus, a vulcanized rubber product is obtained from the composition of the present invention.

In the present invention, the operation for vulcanization is
Conventionally used operation may be adopted. For example, the operation of heating while applying pressure in the mold is adopted,
Alternatively, an operation of heating in a heating furnace or a steam pot after extrusion, molding with a calender roll, etc. may be employed.
Regarding the working conditions during vulcanization, it is desirable to select the optimum conditions according to the raw materials used and the compounding.

The vulcanization conditions are determined by the shape of the molded product to be obtained, etc., but are usually in the range of 100 to 400 ° C. for several seconds to 48 hours. If the heating temperature is increased, the heating time can be shortened. Secondary vulcanization of the obtained vulcanizate can also be adopted, which is useful for improving physical properties. For example, 150 to 300 ° C, preferably 180 ° C to
Secondary vulcanization may be employed at a temperature of 250 ° C. for about 30 minutes to 48 hours.

[0031]

In the present invention, by heating a fluororubber containing an organic phosphorus compound and a divalent metal hydroxide and / or an oxide, an unsaturated bond is introduced into the fluororubber, and at the same time, peroxide is introduced. It is considered that material vulcanization proceeds. Here, since the organophosphorus compound has a higher activity for the introduction reaction of the unsaturated bond as compared with the organic base used in the conventional invention, it is effective without using the unsaturated polyfunctional compound as the vulcanization aid. It is presumed that the organic peroxide vulcanization proceeds further and the properties of the obtained vulcanizate are improved.

[0032]

EXAMPLES According to the compositions (parts by weight) shown in Tables 1 and 2, various compounding materials were uniformly mixed with 2 rolls to obtain rubber compositions. After press vulcanizing them at 170 ° C. for 10 minutes, they were secondarily vulcanized at 230 ° C. for 24 hours in an oven.
According to JIS K6301, the obtained vulcanized product was measured for normal physical properties, heat resistance and oil resistance. The results are shown in Tables 1 and 2. Each of the fluororubbers in Tables 1 and 2 was obtained by an emulsion polymerization method, and the content ratio (molar ratio) of each monomer unit thereof is shown in Table 3. Further, Table 4 shows other abbreviations in Tables 1 and 2.

The compression set was evaluated at 200 ° C. for 70 hours. The mold releasability was visually measured, and the evaluation criteria were as follows. ◎: good, ○: normal, △: somewhat bad,
X: Very bad. The oil resistance was evaluated using engine oil (Toyota Castle Clean SG).

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

INDUSTRIAL APPLICABILITY The present invention provides a fluororubber composition that can be easily vulcanized with an organic peroxide at low cost, and the industrial benefit thereof is extremely large. further,
Based on various excellent vulcanization properties, it is extremely useful in a wide range of applications such as radiators of automobiles, O-rings around engines, gaskets, sealing materials, diaphragms, tubes, hoses, and similar parts such as food plants and chemical plants. It is useful.

Claims (6)

[Claims] 1. A fluororubber obtained by copolymerizing (A) vinylidene fluoride and at least one other ethylenically unsaturated monomer copolymerizable therewith (B) organic peroxide (C) ) A fluororubber composition containing at least one selected from divalent metal hydroxides and divalent metal oxides and (D) an organophosphorus compound. 2. The method according to claim 1, which comprises (E) an organic onium compound.
The fluororubber composition described. 3. The fluororubber composition according to claim 1, wherein the component (A) is a fluororubber obtained by copolymerizing vinylidene fluoride, tetrafluoroethylene and propylene. 4. The component (A) is a fluororubber obtained by copolymerizing vinylidene fluoride and hexafluoropropylene or a fluororubber obtained by copolymerizing vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene. Item 1. A fluororubber composition according to Item 1. 5. The fluororubber composition according to claim 1, wherein the component (D) is a tertiary phosphine. 6. The fluororubber composition according to claim 2, wherein the component (E) is an organic quaternary ammonium hydrogensulfate or an organic quaternary ammonium p-toluenesulfonate.