JPH06271734A - Fluoroelastomer composition - Google Patents

Abstract

PURPOSE:To obtain a fluoroelastomer compsn. with which vulcanization can easily be completed and which has a good releasability from a metal mold and an improved balance between aging resistance in hot air compression set without detriment to the tensile characteristics and chemical resistance. CONSTITUTION:This fluoroelastomer compsn. contains a peroxide-vulcanizable fluoroelastomer component, an org. peroxide, and a polyfunctional cocrosslinker. The elastomer component comprises 90-10wt.% fluorocopolymer which consists of vinylidene fluoride units and at least one kind of other fluoromonomer units and has bromine atoms as crosslinking sites and an intrinsic viscosity [eta] of 40-300ml/g and 10-90wt.% polymer which has molecular terminals with iodine atoms as crosslinking sites and an [eta] of 10-100ml/g.

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 and chemical resistance equivalent to those of conventionally known peroxide-vulcanized fluorine-containing elastomer vulcanizates, while easily completing the vulcanization reaction and releasing the mold. The present invention relates to a fluorine-containing elastomer composition having good moldability and excellent balance between heat aging resistance at high temperature and compression set resistance.

[0002]

Fluorine-containing elastomer vulcanizates which are vulcanized with peroxide have the advantage that they are superior in chemical resistance to fluorine-containing elastomer vulcanizates vulcanized by other methods. In fields, for example, semiconductor-related equipment, general machinery industry, pollution-related departments, automobiles, ships, aircraft, hydraulic equipment, etc., in particular, lubricating oils containing acids and amine-based additives for improving heat resistance, and acids. It is used for O-rings, gaskets, oil seals, diaphragms, hoses, rolls and sheet materials that come into direct contact with bases and bases. However, conventionally known peroxide vulcanizates having bromine as a cross-linking point in the polymer molecular chain, bromine is less likely to be liberated by peroxide as a cross-linking agent during vulcanization molding. Is low, the compression set resistance is poor. On the other hand, the peroxide vulcanizate having iodine at the terminal of the polymer molecular chain as the cross-linking point has a high vulcanization rate because of the high reactivity of iodine, and since the cross-linking density is high, it is excellent in compression set resistance. When exposed to high temperature of 250 ℃ or more for a long time,
Since there is a cross-linking point only at the end of the polymer molecular chain, the physical properties are greatly reduced by cutting the cross-linking point. Therefore, each of the fluorine-containing elastomers has drawbacks and the usable environment is limited.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to provide a vulcanization reaction that has excellent tensile properties and chemical resistance equivalent to those of conventionally known peroxide vulcanized fluorine-containing elastomer vulcanizates. (EN) Provided is a peroxide-vulcanizable fluorine-containing elastomer composition which is completed, has good mold releasability, and has an excellent balance between heat-resistant air-heat aging resistance at high temperature and compression set resistance.

[0004]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors, a component containing bromine as a cross-linking point within a specific intrinsic viscosity [η] range and a specific [η] range It was found that a vulcanized composition using a fluorine-containing elastomer consisting of two components, i.e., a component containing iodine serving as a cross-linking point at the polymer molecular chain end, is suitable for the above purpose, and the present invention was completed based on this finding. Came to do. In the fluorine-containing elastomer composition of the present invention, the fluorine-containing elastomer used as the component (a) is composed of vinylidene fluoride units and at least one other fluorine-containing monomer unit, and contains bromine as a crosslinking point [η ] Is 40 ml / g
It is composed of (a) component of 300 ml / g or less and vinylidene fluoride unit and at least one other fluorine-containing monomer unit, and contains iodine serving as a crosslinking point at the polymer molecular chain end, and [η] is 10 ml. / G or more 100 ml
Per vulcanizable fluorine-containing elastomer having a weight ratio of (a) to (b) of 90% by weight: 10% by weight to 10% by weight: 90% by weight. is there. Further, the component (a) of the present invention is specifically a fluorine-containing elastomer composed of a vinylidene fluoride unit, a hexafluoropropene unit and optionally a tetrafluoroethylene unit, a vinylidene fluoride unit, a perfluorovinyl ether unit and a tetrafluoroethylene unit. It is a fluorine-containing elastomer composed of units, and contains 0.001 to 10% by weight of iodine or bromine bound in the polymer.

To introduce bromine as a crosslinking point, a bromine-containing monomer unit such as bromotrifluoroethylene, 4-bromo-3.3.4.4-tetrafluorobutene-1, brominated fluorovinyl ether is copolymerized. Method (Japanese Patent Publication No. 53-4115, Japanese Patent Laid-Open No. 60-195113, Japanese Patent Laid-Open No. 62-36407, etc.), and a method of polymerizing in the presence of a bromine compound (Japanese Patent Publication No. 3-42302).
Issue). As a method of introducing iodine that can serve as a cross-linking point into the polymer molecular chain end, a method of using an iodine compound as a chain transfer agent (Japanese Patent Publication No. 63-41).
928, JP-A-60-221409, etc.)
Is effective.

The component (a) of the present invention has an [η] of 40 ml /
g or more and 300 ml / g or less, preferably 60 ml / g
The range is 120 ml / g or less. [Η] is 40m
If it is less than 1 / g, the polymer molecular chain becomes shorter than the distance between cross-linking points and sufficient vulcanization cannot be obtained, and [η] is 300 ml /
If it exceeds g, the Mooney viscosity becomes too high and the processing is difficult.

[B] component [η] is 10 ml / g or more 1
00 ml / g or less, preferably 30 ml / g or more 70 m
It is 1 / g or less. When [η] is less than 10 ml / g, it becomes difficult to knead with an open type kneading roll or a closed type kneading roll (Banbury mixer, pressure kneader, etc.),
When [η] exceeds 100 ml / g, the distance between cross-linking points becomes too long and the compression set resistance is significantly deteriorated.

The amount of iodine or bromine bound in the polymer of component (a) or component (b) of the present invention is 0.001 to 10% by weight, preferably 0.005 to 5% by weight. If the amount of iodine or bromine is less than 0.001% by weight, a sufficient crosslinking density cannot be obtained and the compression set resistance is inferior. If it exceeds 10% by weight, the crosslinking density becomes too high and the elastomer elasticity is lost.

The weight ratio of the components (a) and (b) is 90% by weight: 10% by weight to 10% by weight: 90% by weight, preferably 70% by weight: 30% by weight to 30% by weight: 70% by weight. In range. When the weight ratio of the component (a) exceeds 90% by weight, the rate of vulcanization becomes slow and the compression set is not improved. When the weight ratio of the component (a) is less than 10% by weight, the heat aging resistance to heat-resistant air does not improve.

Specific examples of the component (a) when the component (a) of the present invention is obtained as an elastomer blend include vinylidene fluoride units, hexafluoropropylene units and tetrafluoroethylene units, and bromine as a crosslinking point. E-I Dupont de Nimoas and
Company product "Viton GF", "Viton VTR-
6510 ”,“ Viton VTR-5927 ”, Minnesota Mining and Manufacturing Company product“ Florel FLS-2690 ”, etc. Contains E-I-Dupont de Nimoas
And company products "Viton GLT", "Viton GFLT" and the like. Specific examples of the component (b) include "Daiel G-801", a product of Daikin Industries, Ltd., containing vinylidene fluoride units and hexafluoropropylene units as crosslinking points, vinylidene fluoride units, and hexafluoropropylene units. And a product of Daikin Industries, Ltd., which contains iodine and tetrafluoroethylene units as crosslinking points, "Daiel G-90"
1 "," Dayer G-902 "," Daiel G-91 "
2 "," DAI-EL G-952 ", Asahi Kasei Kogyo Co., Ltd. product" Milafron FR-6140 "," Milaflon FR-
6340 "," MIRAFRON FR-6150 "," MIRAFRON FR-6350 "," MIRAFRON FR-6360 "
And so on.

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 blending ratio of the organic peroxide component in the fluorine-containing elastomer composition of the present invention is usually (a) component 10
It is 0.05 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 0 parts by weight. If the amount of the component (b) is less than 0.05, the vulcanization rate is slow, and the mold releasability is poor. If it exceeds 5 parts by weight, the compression set resistance is significantly deteriorated.

The polyfunctional co-crosslinking agent as the component (c) is, for example, triallyl cyanurate, trimethallyl isocyanurate, triallyl isocyanurate, triacrylic 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 fluorine-containing elastomer composition of the present invention is usually 0.1 to 1 with respect to 100 parts by weight of the component (a).
It is 0 part by weight, preferably 0.2 to 6 parts by weight. (C)
If the amount of the component is less than 0.1 part by weight, a sufficient crosslinking density cannot be obtained. When it exceeds 10 parts by weight, the component (c) bleeds to the rubber surface during molding, which causes defective molding.

Further, in the fluorine-containing elastomer 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,
Fillers such as silicone grease, stearic acid, calcium stearate, magnesium stearate, aluminum stearate, zinc stearate, titanium white, red iron oxide, etc., processing aids, plasticizers, colorants, etc. can be blended and acid-accepted. As the agent, for example, lead oxide, ferric phosphite, magnesium oxide, zinc oxide, calcium oxide, calcium hydroxide, hydrotalcite compound and the like may be blended. Further, a conventionally known vulcanizing agent or vulcanization accelerator may be blended within a range not departing from the gist of the present invention.

The method for vulcanizing the fluorine-containing elastomer composition of the present invention is, for example, an open type kneading roll or a closed type kneading roll (Banbury mixer, pressure kneader, etc.).
After kneading with, the mixture is put into a mold and pressurized to perform primary vulcanization, and then secondary vulcanization. Generally, the conditions for primary vulcanization are a temperature of 120 to 200 ° C., a time of 1 to 180 minutes, and a pressure of 20.
The range of 150 to 150 kg / m ^{2 and} the range of temperature of 120 to 250 ° C. and time of 0 to 48 hours are adopted as the secondary vulcanization conditions. As other vulcanizing means, a method of vulcanizing after preforming such as injection or extrusion, or one or more of methyl ethyl ketone, ketones such as acetone, ethyl ether, ethers such as tetrahydrofuran, etc. may be used. Prepare a solution or dispersion as a medium,
It is also possible to use a method in which the surface of paper, fiber, film, sheet, plate, tube, pipe, tank, large container or other molded article is coated and vulcanized.

[0015]

Example The intrinsic viscosity [η] of the fluoroelastomer, and the vulcanization characteristics and physical properties of the fluoroelastomer composition were determined by the following methods. (1) [.eta.] Is 0.
A 1 g / 100 ml concentration solution was prepared and measured at 35 ° C. using a capillary viscometer.

(2) The vulcanization time T90 was measured using the Orientometer V-type Clastometer, manufactured by Orientec Co., Ltd., at a temperature of 16
The measurement was performed under the conditions of 0 ° C., frequency of 100 cpm, and amplitude angle of 1 °. (3) The hardness [JIS-A], 100% tensile stress, tensile strength, and elongation of the vulcanized product were measured according to JIS-K6301. (4) The compression set was measured according to JIS-K6301 at a temperature of 200 ° C. for 70 hours.

(5) Hot air heating aging test is JIS-K63
According to No. 01, the temperature was measured at 275 ° C. for 72 hours. (6) The mold releasability is judged by the ease of releasing the tensile property sheet from the mold and the burr adhesion.
Displayed in four levels of ⊚, ○, Δ, and ×.

[0018]

Example 1 Intrinsic viscosity [η] is 100 ml / g, vinylidene fluoride unit is 52.4% by weight, hexafluoropropene unit is 25% by weight, tetrafluoroethylene unit is 22% by weight, and bromine is 0.6% by weight. Fluorine-containing elastomer containing 50 parts by weight (hereinafter, referred to as Br-FKM), [η] is 50 ml / g, vinylidene fluoride unit 52.6.
% Fluorine, 25% by weight of hexafluoropropene unit and 22% by weight of tetrafluoroethylene unit, and 0.4% by weight of iodine which can be a crosslinking point at the end of the polymer molecular chain (hereinafter referred to as I-FKM).
Wrap 50 parts by weight around an open type kneading roll and use CANCAR
Company B product MT carbon black "Thermax N-99
20 parts by weight of 0 "and 3 parts by weight of low activity magnesium oxide" Kyowamag 30 "manufactured by Kyowa Chemical Industry Co., Ltd. are kneaded. Next, knead 4 parts by weight of triallyl isocyanurate “TAIC” manufactured by Nippon Kasei Co., Ltd. and 3.75 parts by weight of organic peroxide “Perhexa 25B-40 (peroxide content is 40% by weight)” manufactured by NOF CORPORATION. And left it overnight for aging. Then, after re-kneading, it was put into a mold and press-vulcanized at a temperature of 160 ° C. for 10 minutes to form a sheet having a thickness of 2 mm and a right cylindrical test piece for measuring compression set. Then, it was taken out from the mold and heated in an air circulation type furnace at a temperature of 180 ° C. for 4 hours to complete the secondary vulcanization, and various tests were conducted. Table 1 shows the normal physical properties, compression set, hot air heating aging test, and mold releasability of the vulcanized molded product thus obtained.

[0019]

[Comparative Example 1] Br-FKM was added to 1 without using I-FKM.
Various tests were carried out in the same manner as in Example 1 except that the amount was 00 parts by weight and the press vulcanization time was 30 minutes. The results are shown in Table 1.

[0020]

[Comparative Example 2] I-FKM was set to 1 without using Br-FKM.
Various tests were conducted in the same manner as in Example 1 except that the amount was set to 00 parts by weight. The results are shown in Table 1. Example 1 and Comparative Examples 1 and 2
In contrast, the rate of vulcanization and the compression set resistance are the same as those of Comparative Example 2, but the elongation change rate in the hot air heating aging test is significantly improved. Furthermore, it is clear that the two-component elastomer is in a good dispersed state, with no deterioration in normal physical properties. Moreover, the mold releasability is also good.

[0021]

[Table 1]

[0022]

The peroxide-vulcanizable fluorine-containing elastomer composition of the present invention has excellent tensile properties and chemical resistance equivalent to those of conventionally known peroxide-vulcanizable fluorine-containing elastomer compositions. The vulcanization reaction is easily completed, the mold releasability is good, and the balance between heat aging resistance to hot air at high temperature and compression set resistance is excellent, and its industrial value is extremely high.

Claims (1)

[Claims] 1. A method comprising: (a) a vinylidene fluoride unit and at least one other fluorine-containing monomer unit, containing bromine as a crosslinking point, and having an intrinsic viscosity [η] of 40 ml / g or more and 300 ml / g or less. A component (a), a vinylidene fluoride unit and at least one other fluorine-containing monomer unit, and contains iodine serving as a cross-linking point at the polymer molecular chain end, and [η] is 10 ml / g or more and 100 ml / g or more.
a peroxide vulcanizable fluorine-containing elastomer, which is composed of the component (b) of not more than g and has a weight ratio of (a) to (b) of 90% by weight: 10% by weight to 10% by weight: 90% by weight, A fluorine-containing elastomer composition comprising b) an organic peroxide and (c) a polyfunctional co-crosslinking agent.