JPH05279535A - Vulcanizable fluoroelastomer composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition markedly improved in heat aging resistance and compression set at high temperatures by adding a specified phenolic antioxidant to a vulcanizable peroxide-vulcanizable fluoroelastomer composition. CONSTITUTION:This composition comprises a peroxide-vulcanizable fluoroelastomer, an organic peroxide, a polyfunctional covulcanizer and a phenolic antioxidant containing 1-4 hydroxyphenyl groups each containing 1 or 2-butyl groups in the molecule. The fluoroelastomer may be one containing bromine or iodine at the molecular terminals or in the main chain and therefore being vulcanizable with an organic peroxide. An example of a process for effectively introducing iodine into the molecular terminals comprises using an iodine compound as a chain transfer agent. An example of a known process for introducing bromine or iodine into the main chain comprises using a crosslinking monomer containing bromine or iodine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel vulcanizing composition for fluorine-containing elastomer. More specifically, the present invention has excellent tensile properties, heat resistance, and equivalent to conventionally known peroxide-vulcanized fluorine-containing elastomer vulcanizates.
The present invention relates to a peroxide-vulcanized fluorine-containing elastomer vulcanized composition having improved chemical resistance and heat aging resistance and sealability at high temperatures.

[0002]

2. Description of the Related Art Fluorine-containing elastomer vulcanizates that are vulcanized with peroxide are said to have significantly better chemical resistance than fluoroelastomer vulcanizates that are currently vulcanized with polyol compounds. Owing to its characteristics, it can be used in various industrial fields such as general machinery industry, pollution-related departments, automobiles, ships, aircraft, hydraulic equipment, etc., especially O-rings, gaskets, oil seals, diaphragms that come into direct contact with acids and bases. It is used for hoses, rolls, and sheet materials. However, since the fluorine-containing elastomer that is peroxide-vulcanized has an essential defect that the cross-linking point is easily broken by oxygen at a high temperature of 200 ° C. or higher, it is more preferable than the fluorine-containing elastomer vulcanized product that is vulcanized with a polyol compound. Inferior in heat aging resistance and compression set resistance at high temperature. Therefore, the environment in which it can be used was limited, and frequent parts replacement was necessary.

[0003]

The object of the present invention is to provide heat aging resistance and high temperature aging resistance while maintaining excellent tensile properties and chemical resistance equivalent to those of conventionally known peroxide vulcanized fluorine-containing elastomer vulcanizates. It is an object of the present invention to provide a peroxide-vulcanized fluorine-containing elastomer vulcanized composition having significantly improved compression set resistance.

[0004]

Means for Solving the Problems As a result of intensive studies by the present inventors, a vulcanized composition obtained by blending a peroxide-vulcanized fluorine-containing elastomer vulcanized composition with a specific phenolic antioxidant was found. The inventors have found that they meet the above-mentioned object, and have completed the present invention based on this finding. That is, the present invention comprises (a) a peroxide-vulcanizable fluorine-containing elastomer, (b) an organic peroxide, (c) a polyfunctional co-crosslinking agent, and (d) one or two tert-butyl groups. The present invention relates to a fluorine-containing elastomer vulcanizing composition comprising a phenolic antioxidant containing 1 to 4 hydroxyphenyl groups in one molecule.

The fluorine-containing elastomer used as the component (a) in the fluorine-containing elastomer vulcanizing composition of the present invention is a vinyl-containing elastomer containing vinylidene fluoride unit, hexafluoropropene unit and optionally tetrafluoroethylene unit, vinylidene fluoride. Units, perfluorovinyl ether units and tetrafluoroethylene units, fluorine-containing elastomers, perfluorovinyl ether and tetrafluoroethylene units, fluorine-containing elastomers, tetrafluoroethylene units and propylene units, and optionally vinylidene fluoride units , Fluorophosphazene elastomers and the like. Further, the fluorinated elastomer may contain bromine or iodine in the polymer terminal or main chain to enable organic peroxide crosslinking. As a method for introducing iodine into the polymer terminal, a method using an iodine compound as a chain transfer agent (Japanese Patent Publication No. 63-41928).
JP-A No. 60-221409) is effective. Further, it is known that a crosslinking point monomer containing bromine or iodine is used to introduce bromine or iodine into the main chain.

Specific examples of the fluorine-containing elastomer of the present invention include "Viton GF" and "Viton VTR-" manufactured by E. I. DuPont de Nimours and Company.
5927 "," Viton GLT "," Viton GFL "
T "from Minnesota Mining and Manufacturing Company" Florel FLS-269
0 "," Technoflon P2 "," Technoflon P40 "manufactured by Montedison S. P.A.I," Daiel G-801 "," Daiel G-90 "manufactured by Daikin Industries, Ltd.
1 "," DAIEL G-902 "," DAIEL G-91 "
2 "," Daiel G-1001 "," Aipel-F ",
Asahi Glass Co., Ltd. "Afras 150", "Afras 20"
0 "," Mirafuron FR-614 "manufactured by Asahi Kasei Corporation
0 "," Milaflon FR-6340 "," Milaflon F
R-6150 "," Milafuron FR-6350 "," Milafuron FR-6360 ", etc. are mentioned.

As the organic peroxide as the component (b), an organic peroxide which generates a peroxide radical under vulcanization conditions is used, and for example, 1,1-bis (tert-butylperoxy) -3,5. , 5-trimethylcyclohexane, 1,
1-bis (tert-butylperoxy) cyclohexane, 2,2-bis (tert-butylperoxy) octane, n-butyl 4,4-bis (tert-butylperoxy) valerate, 2,2-bis (tert) -Butylperoxy) butane, 2,5-dimethylhexane-2,
5-dihydroxy peroxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide,
Dicumyl peroxide, α, α′-bis (tert-butylperoxy-m-isopropyl) benzene, 2,5
-Dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (ter
t-butylperoxy) hexyne-3, benzoyl peroxide, tert-butylperoxybenzene, 2,
5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxymaleic acid, te
Examples thereof include rt-butyl-oxyisopropyl carbonate. The mixing ratio of the organic peroxide component in the fluorinated elastomer vulcanization composition of the present invention is usually 0.05 to 5 parts by weight, preferably 0.1 to 3 parts by weight, relative to 100 parts by weight of the component (a). Is.

The polyfunctional co-crosslinking agent as the component (c) is, for example, triallyl cyanurate, trimethallyl isocyanurate, triallyl isocyanurate, triacryl formal, triallyl trimellitate, N, N'-m-phenylene. Bismaleimide, diallyl phthalate, tetraallyl terephthalamide, tris (diallylamine)-
Examples thereof include s-triazine, triallyl phosphite, and N, N-diallyl acrylamide. The compounding ratio of the polyfunctional co-crosslinking agent in the fluorinated elastomer vulcanizing composition of the present invention is usually 0.1 with respect to 100 parts by weight of the component (a).
10 to 10 parts by weight, preferably 0.2 to 6 parts by weight.

The component (d) is a phenolic antioxidant containing 1 to 4 hydroxyphenyl groups having 1 or 2 tert-butyl groups in one molecule, for example, tris (3,5-di-). tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-trimethyl-
2,4,6-Tris (3,5-di-tert-butyl-
4-hydroxybenzyl) benzene, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5) -Methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5
-Di-tert-butyl-4-hydroxyphenyl) propionate], N, N-hexanemethylenebis (3,3)
5-di-tert-butyl-4-hydroxyhydrocinnamamide), 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester,
Bis (3,5-di-tert-butyl-4-hydroxybenzylphosphonate ethyl) calcium, N, N-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,
4-bis (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3
5-triazine, octadecyl-3- (3,5-di-t
ert-butyl-4-hydroxyphenyl) propionate and the like, and particularly preferred one is tris (3,3
5-di-tert-butyl-4-hydroxybenzyl)
Isocyanurate. Further, two or more of these may be combined. The blending ratio of the component (d) in the fluorinated elastomer vulcanization composition of the present invention is usually (a)
It is 0.1 to 10 parts by weight, preferably 0.2 to 5.0 parts by weight, relative to 100 parts by weight of the component. When the amount of the component (d) of the present invention is within this range, a sufficient improvement in heat resistance cannot be obtained when the amount is less than 0.1 parts by weight, and the tensile strength of the vulcanized product is significantly reduced when the amount exceeds 10 parts by weight. This is because.

Further, in the fluorine-containing elastomer vulcanization composition of the present invention, if necessary, other components such as carbon black, austin black, graphite, silica, clay, diatomaceous earth, talc, wollastonite, calcium carbonate, Calcium silicate, calcium fluoride, barium sulfate, sulfone compound, phosphate ester, fatty amine, higher fatty acid ester, fatty acid calcium, fatty acid amide, low molecular weight polyethylene, silicone oil, silicone grease, stearic acid, calcium stearate, magnesium stearate, Aluminum stearate, zinc stearate, titanium white,
Fillers such as red iron oxide, processing aids, plasticizers, colorants and the like can be blended, and as an acid acceptor, for example, lead oxide, ferric phosphite, magnesium oxide, zinc oxide, calcium oxide, and hydroxide. You may mix calcium, a hydrotalcite compound, etc. Further, one or two conventionally known vulcanizing agents or vulcanization accelerators may be blended within a range not departing from the gist of the present invention.

The fluorinated elastomer vulcanized composition thus obtained may be vulcanized by, for example, kneading with an open-type kneading roll or a closed-type kneading roll (Banbury mixer, pressure kneader, etc.), and then putting into a mold. A method of applying pressure to perform primary vulcanization and then secondary vulcanization can be mentioned. Generally, the conditions of primary vulcanization are a temperature of 120 to 200 ° C. and a time of 1 to 1
A range of 80 minutes, a pressure of 20 to 150 kg / m ² and a temperature of 120 to 250 ° C. and a time of 0 to 48 hours are adopted as the conditions of the secondary vulcanization. As another vulcanizing means, a method of vulcanizing after preforming such as injection or extrusion,
Alternatively, a solution or dispersion containing one or more of ketones such as methyl ethyl ketone and acetone, ethers such as ethyl ether and tetrahydrofuran as a medium is prepared, and paper, fiber, film, sheet,
It is also possible to use a method of coating and vulcanizing the surface of a molded product such as a plate, tube, pipe, tank, large container and the like.

[0012]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. The physical properties of the fluorinated elastomer vulcanized composition were determined by the methods described below. (1) The hardness [JIS-A], 100% tensile stress, tensile strength and elongation of the vulcanized product were measured according to JIS-K6301.

(2) The compression set is JIS-B240
Use P-24 of the exercise O-ring specified in 1 and 2
It was measured according to ASTM-D1414 under the condition of 00 ° C x 70 hours. (3) The hot-air heating aging test was performed according to JIS-K6301 under the condition of a temperature of 230 ° C. × 168 hours.

[0014]

Example 1 100 parts by weight of "Milafuron FR-6350" containing vinylidene fluoride unit / hexafluoropropene unit / tetrafluoroethylene unit and having a fluorine content of 68% by weight, which is a crosslinking point, was used as an open type mill roll. 20 parts by weight of "THERMAX N-990" manufactured by CANCARB and 3 parts by weight of "Kyowamag 30" manufactured by Kyowa Chemical Industry Co., Ltd. Next, triallyl isocyanurate “TAIC” manufactured by Nippon Kasei Co., Ltd.
After kneading 4 parts by weight and 3.75 parts by weight of an organic peroxide “Perhexa 25B-40” manufactured by NOF CORPORATION, tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate 1 0.0 part by weight was kneaded, and the mixture was left to stand overnight for aging.

Then, after kneading again, it is put in a mold,
Press vulcanization is performed for 10 minutes at a temperature of 160 ° C.
Molded into a ring. Then remove from the mold, temperature 18
Various tests were carried out by heating in an air circulation type furnace at 0 ° C. for 4 hours to complete the secondary vulcanization. Table 1 shows the normal physical properties, compression set, and hot air heating aging test of the vulcanized molded product thus obtained.

[0016]

Example 2 Tris (3,5-di-tert-butyl-
Various tests were conducted in the same manner as in Example 1 except that 1.0 part by weight of 4-hydroxybenzyl) isocyanurate was changed to 2.0 parts by weight. The results are shown in Table 1.

[0017]

Example 3 Tris (3,5-di-tert-butyl-
Various tests were conducted in the same manner as in Example 1 except that 1.0 part by weight of 4-hydroxybenzyl) isocyanurate was changed to 3.0 parts by weight. The results are shown in Table 1.

[0018]

Example 4 Tris (3,5-di-tert-butyl-
Various tests were conducted in the same manner as in Example 1 except that 1.0 part by weight of 4-hydroxybenzyl) isocyanurate was changed to 5.0 parts by weight. The results are shown in Table 1.

[0019]

Comparative Example 1 Tris (3,5-di-tert-butyl-
Various tests were carried out in the same manner as in Example 1 except that 1.0 part by weight of 4-hydroxybenzyl) isocyanurate was not used. The results are shown in Table 1.

[0020]

Example 5 Tris (3,5-di-tert-butyl-
4-Hydroxybenzyl) isocyanurate 1.0 part by weight is replaced by 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene 2.0 Example 1 except that parts by weight are used
Various tests were conducted in the same manner as in. The results are shown in Table 2.

[0021]

Example 6 Tris (3,5-di-tert-butyl-
4-Hydroxybenzyl) isocyanurate Instead of 1.0 part by weight pentaerythrityl-tetrakis [3-
(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] Various tests were conducted in the same manner as in Example 1 except that the amount was 2.0 parts by weight. The results are shown in Table 2.

The examples in which the phenolic antioxidant of the present invention was blended with the peroxide-vulcanizable fluorine-containing elastomer had smaller changes in physical properties in the hot air heating aging test than the comparative examples in which the phenolic antioxidant was not used, Moreover, it is clear that the compression set resistance at high temperatures has been greatly improved, and the breaking of cross-linking points by oxygen is less likely to occur.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

The peroxide vulcanizable fluorine-containing elastomer vulcanizing composition of the present invention has the drawbacks of the conventionally known peroxide vulcanizable fluorine-containing elastomer vulcanizing composition, which are the disadvantages of heat aging resistance and high temperature aging. Significantly improved sealing properties. Therefore, if it is used as a sealing part such as an O-ring, it becomes possible to maintain the sealing property for a long period of time, and the product life is greatly extended, and the industrial value is extremely high.

Claims (2)

[Claims] 1. A fluorine-containing elastomer capable of peroxide vulcanization, (b) an organic peroxide, (c) a polyfunctional co-crosslinking agent, and (d) one or two tert-butyl groups. A fluorine-containing elastomer vulcanizing composition comprising a phenolic antioxidant containing 1 to 4 hydroxyphenyl groups in one molecule. 2. The fluorine-containing elastomer vulcanizing composition according to claim 1, wherein the component (a) is a peroxide-vulcanizable fluorine-containing elastomer containing bromine or iodine.