JPH03100039A - Fluoroelastomer composition - Google Patents

Abstract

PURPOSE:To improve the solvent resistance, chemical resistance, and low temp. properties by compounding a tetrafluoroethylene-perfluoro(methyl vinyl ether) copolymer with a tetrafluoroethylene-perfluoro(methyl vinyl ether)-vinylidene fluoride terpolymer in a specified ratio. CONSTITUTION:About 99-50 pts.wt. tetrafluoroethylene-perfluoro(methyl vinyl ether) copolymer is compounded with about 1-50 pts.wt. tetrafluoroethylene- perfluoro(methyl vinyl ether)-vinylidene fluoride terpolymer to give a fluoroelastomer compsn. In place of the copolymer, a terpolymer comprising tetrafluoroethylene, perfluoro(methyl vinyl ether), and a fluorovinyl ether of the general formula: CF2=CF(OCF2CFX)nORf (wherein Rf is perfluoroalkyl; X is fluorine or trifluromethyl; and (n) is a positive integer) may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to fluoroelastomer compositions. More specifically, the present invention relates to a fluoroelastomer composition having excellent solvent resistance, chemical resistance, and low-temperature properties.

[Conventional technology]

In general, tetrafluoroethylene and perfluoro(
methyl vinyl ether), or a copolymer obtained by further copolymerizing this with a fluorovinyl ether represented by the general formula CF, =CF(OCF2CFX)nORf (JP-A-58-71906, JP-A-64-229)
No. 08) are generally used in painting lines in the automobile industry because their polymers are composed of C-F bonds that exhibit strong resistance to chemicals.

It also shows excellent resistance to ketones such as acetone, which have a negative effect on rubber.

However, these copolymers generally have problems such as difficulty in copolymerization reactions, low yields, and the use of expensive perfluoro(methyl vinyl ether), which increases the product price. It has the disadvantage that it may result in excessive quality for solvents, chemicals, etc. Furthermore, due to the high fluorine content in the copolymer, the low-temperature properties are poor, and TR-10, which is a guideline for low-temperature properties and crystallization tendency.
The value is as high as -3 to -9°C.

On the other hand, the tetrafluoroethylene-perfluoro(methyl vinyl ether)-vinylidene fluoride terpolymer is
It has excellent low-temperature properties with a TR-10 value of -24°C, and the copolymerization reaction progresses relatively easily, so it can be produced at a lower cost than perfluoro-type copolymers, but it has poor chemical resistance during copolymers. Contains vinylidene fluoride, so it has poor solvent and chemical resistance.

[Problem to be solved by the invention]

An object of the present invention is to solve these problems and provide a composition of a fluoroelastomer that has excellent solvent resistance, chemical resistance, and low-temperature properties, and is moreover inexpensive.

[Means to solve the problem]

The object of the present invention is to produce a copolymer of tetrafluoroethylene and perfluoro(methyl vinyl ether) or a copolymer of tetrafluoroethylene and perfluoro(methyl vinyl ether) with the general formula CF2=CF (OCF, CF
X) n0Rf [Here, Rf is a perfluoroalkyl group, generally a perfluoroalkyl group having 1 to 6 carbon atoms, X is a fluorine atom or a trifluoromethyl group, and n is a positive integer.

Generally, about 99 to 50 parts by weight of a copolymer with fluorovinyl ether represented by an integer from 1 to 5, and about 1 to 50 parts by weight of a tetrafluoroethylene-perfluoro(methyl vinyl ether)-vinylidene fluoride terpolymer This is achieved with a fluoroelastomer composition comprising 50 parts by weight.

As a copolymer of tetrafluoroethylene and perfluoro(methyl vinyl ether), tetrafluoroethylene is about 40 to 70 mol%, preferably about 50 to 60 mol%, and perfluoro(methyl vinyl ether) is about 60 mol%.
A copolymer composition having a copolymerization composition of ~30 mol2, preferably about 50-40 mol% is used.

Further, as a copolymer of tetrafluoroethylene, perfluoro(methyl vinyl ether), and fluorovinyl ether, about 30 to 80 moles of tetrafluoroethylene2. Preferably about 40 to 60 moles perfluoro(
5 to 60 mol % (methyl vinyl ether), preferably about 30 to 50 mol %, and about 3 fluorovinyl ether
A copolymer composition having a copolymerization composition of ~50 mol%, preferably about 5-15 mol% is used.

Furthermore, the tetrafluoroethylene-perfluoro(methyl vinyl ether)-vinylidene fluoride terpolymer contains about 5 to 30 mol% of tetrafluoroethylene, preferably about 10 to 25 mol% of perfluoro(methyl vinyl ether). is about 10 to 30 mol%, preferably about 2
A copolymer composition having a copolymer composition of 0 to 30 mol % and vinylidene fluoride of about 50 to 80 mol %, preferably about 50 to 60 mol % is used.

These copolymers can be produced by bulk polymerization, suspension polymerization, solution polymerization, etc., but preferably by emulsion polymerization. During copolymerization reactions using these various polymerization methods, if an iodine-containing bromine compound is present in the reaction system, iodine and bromine will bond to the molecular terminals of the resulting copolymer in a radically active state, resulting in It enables peroxide vulcanization of a copolymer using peroxide as a radical source in the presence of a polyfunctional compound such as triallyl isocyanurate or triallyl cyanurate.

Examples of such iodine-containing bromine compounds include 1-bromo-2-iodoperfluoroethane, I-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, and 1-bromo-2-iodo- A chain compound represented by 1 chlorperfluoroethane or 0-2I- or p-iodobromobenzene,
Aromatic compounds represented by 3,5-dibromo-1-iodobenzene, 3,5-short-1-bromobenzene, etc. have approximately 0% iodine and bromine, respectively.
．． 0.01 to 5% by weight, preferably about 0.05 to 3% by weight.

Copolymer of tetrafluoroethylene and perfluoro(methyl vinyl ether) or copolymer of tetrafluoroethylene, perfluoro(methyl vinyl ether) and fluorovinyl ether and tetrafluoroethylene-
The perfluoro(methyl vinyl ether)-vinylidene fluoride terpolymer is about 99 to 50 parts by weight of the former, preferably about 99 to 70 parts by weight, and about 1 to 50 parts by weight of the latter, preferably about 1 to 50 parts by weight. It is used by blending it in a proportion of 30 parts by weight. If the ratio of the latter is less than this, the solvent resistance and chemical resistance will be poor, while if the ratio of the latter is blended above this, the low temperature properties will be impaired, both of which are not preferred.

A fluoroelastomer composition made of a blend of these two components can be co-crosslinked by various conventionally known vulcanization methods, such as peroxide vulcanization using an organic peroxide, or irradiation with radiation, electron beam, etc. However, in the peroxide vulcanization method, the co-crosslinked elastomer has excellent mechanical strength and the structure of the crosslinking point forms a stable carbon-carbon bond, resulting in excellent solvent and chemical resistance. This is a particularly preferred method because it provides an excellent vulcanizate.

Examples of organic peroxides used in the peroxide vulcanization method include 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-
Bis(tert-butylperoxy)hexyne-3, benzoyl peroxide, bis(2,4-dichlorobenzoyl)
Peroxide, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide, tert-butyl peroxybenzene, 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane ,
2,5-dimethylhexane-2,5-dihydroxyperoxide, α,α'-bis(tert-butylperoxy)-
ρ-diisopropylbenzene, 2,5-dimethyl-2,
5-di(benzoylperoxy)hexane, tert-butylperoxyisopropyl carbonate, etc. are used.

In the peroxide vulcanization method in which these organic peroxides are used, polyfunctional unsaturated compounds such as tri(meth)allyl isocyanurate, tri(meth)allyl cyanurate, tri(meth)allyl are usually used as co-crosslinking agents. trimellitate, N,N'-1m-phenylenebismaleimide,
Diallyl phthalate, tris(diallylamine)-s-
Triazine, triallyl phosphite, 1,2-polybutadiene, ethylene glycol diacrylate, diethylene glycol diacrylate, etc. are used in combination for the purpose of obtaining better vulcanization properties, mechanical strength, and compression set.

Depending on the purpose, metal hydroxides, oxides or carbonates may be used as crosslinking aids, such as calcium, magnesium, barium, sodium, gethium, potassium, etc.
Hydroxides such as zinc and iron (III), oxides such as calcium, magnesium, copper, zinc, button, sodium, potassium, barium, calcium, magnesium, zinc,
Carbonates such as sodium, potassium, and lithium, as well as basic layer lead phosphate, etc., are used.

The above components added to the peroxide vulcanization system generally contain about 0.1 to 10 parts by weight of organic peroxide, preferably about 0 parts by weight, per 100 parts by weight of the fluoroelastomer blend.
．． The co-crosslinking agent is used in an amount of about 1 to 10 parts by weight, preferably about 0.5 to 5 parts by weight, and the crosslinking aid is used in an amount of about 15 parts by weight or less. It will be done.

The above vulcanization system components may be mixed with the fluoroelastomer as is and kneaded, or they may be diluted with carbon black, silica, clay, talc, diatomaceous earth, barium sulfate, etc., or mixed with the fluoroelastomer. Used as a batch dispersion. In addition to the above-mentioned components, the formulation contains conventionally known fillers, reinforcing agents, plasticizers,
A lubricant, a processing aid, a pigment, etc. can also be blended as appropriate.

Vulcanization is performed by mixing the above-mentioned components by a commonly used mixing method such as roll mixing, kneader mixing, Banbury mixing, solution mixing, etc., and then heating the mixture.

Heating generally includes primary vulcanization at about 100-250°C in an amount of about 1-30 parts by weight and 0-30 parts by weight at about 150-300°C.
This is done by secondary vulcanization which takes about 30 hours.

【Effect of the invention〕

The fluoroelastomer composition according to the present invention has a volume change rate of about 8 when immersed in acetone at 25°C for 70 hours.
0% or less, and has good low-temperature properties with a TR-10 value of 15°C or less, showing well-balanced properties. By blending the terpolymer, the amount of expensive perfluoro-type elastomer can be reduced, and costs can be reduced.

The fluoroelastomer composition of the present invention having such characteristics can be effectively used as a molding material for sealing materials such as oil seals, packings, and gaskets for aircraft, fuel tanks, petrochemical plants, automobiles, and various mechanical devices.

〔Example〕

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

Reference example 1 In an autoclave with an internal volume of 3Q, deionized water 960+
en, 1-bromo-2-iodoperfluoroethane 1
．． 8g, ammonium perfluorooctanoate 4.2g
, disodium hydrogen phosphate dodecahydrate 4.2g, sodium hydroxide 0.075g, ammonium persulfate 4.8g
g and 0.3 g of sodium acid sulfite, then perfluoro(methyl vinyl ether) [FMVB14
80 g and tetrafluoroethylene [TFE] 192
I prepared g.

After carrying out the copolymerization reaction at a reaction temperature of 50° C. for 24 hours, the reaction was stopped by purging the unreacted gas in the autoclave. A 5% potassium alum aqueous solution was added to the resulting aqueous emulsion to coagulate the resulting copolymer, which was then washed with water and dried to obtain TFE (FMVE)1. / ratio is 52/48,
[η] = 0.4 (Dweller 3M product Fluorinert FC-77
410 g of a rubbery copolymer with a temperature of 35° C. was obtained.

Reference Example 2 388 g of perfluoro(methyl vinyl ether), 170 g of tetrafluoroethylene and formula CF, =CF[O
CF, CF (CF3)] Fluorovinyl ether represented by 20C3F7 [Reference example 1 using 1270 g of FVE
Copolymerization reaction was carried out in the same manner as above for 22 hours, TFE: F
MVE: FVE molar ratio is 49/44/7, [η]
428 g of a rubbery ternary copolymer of =0.3 (in Florinat FC-77, 35°C) was obtained.

Reference Example 3 208 g of perfluoro(methyl vinyl ether), 75 g of tetrafluoroethylene and vinylidene fluoride [V
Using 192 g of TFE:FM, a copolymerization reaction was carried out for 23 hours in the same manner as in Reference Example 1 (however, 0.4 g of ammonium persulfate and no sodium acid sulfite were used).
VE: VdF mo/l/ratio is 15/25/60te,
472 g of a rubbery ternary copolymer with [η]=2.5 (in methyl ethyl ketone, 35° C.) was obtained.

Examples 1 to 5, Comparative Examples 1 to 6 100 parts of the iodine- and bromine-containing fluoroelastomer blend obtained in each of the above reference examples (weight, same hereinafter),
Roll 20 parts of carbon black, 4 parts of triallyl isocyanurate (60% a degree), 2 parts of 2,5-dimethyl-2°5-ditert-butyl peroxyhexane (40% concentration) and 3 parts of lead oxide. The fluoroelastomer composition prepared by mixing was subjected to primary vulcanization at 180°C for 10 minutes and secondary vulcanization at 200°C for 22 hours.

Vulcanization molding was carried out into a sheet and a P-240 ring.

Regarding this sheet, in accordance with JIS K-6301, the normal value, the TR test which is a guide for low temperature characteristics, and the volume change rate after 70 hours immersion in acetone at 25 °C were measured. Compression set was measured under conditions of 25% compression for 70 hours. The results obtained are
As shown in the table below.

(Margin below)

Claims (1)

[Scope of Claims] 1. About 99 to 50 parts by weight of a copolymer of tetrafluoroethylene and perfluoro(methyl vinyl ether) and about a tetrafluoroethylene-perfluoro(methyl vinyl ether)-vinylidene fluoride terpolymer 1-50
A fluoroelastomer composition consisting of parts by weight. 2. Tetrafluoroethylene and perfluoro(methyl vinyl ether) and the general formula CF_2=CF(OCF_2CFX)nORf [where Rf is a perfluoroalkyl group, X is a fluorine atom or a trifluoromethyl group, and n is from about 99 to 50 parts by weight of a copolymer with fluorovinyl ether represented by [a positive integer] and about 1 to 50 parts by weight of a tetrafluoroethylene-perfluoro(methyl vinyl ether)-vinylidene fluoride terpolymer A fluoroelastomer composition.