JP2509345B2 - Fluorine rubber vulcanizing composition having high tensile strength - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel vulcanizing composition of fluororubber.

[Conventional technology]

Fluorinated rubber vulcanizates have excellent heat resistance, oil resistance, chemical resistance, etc., so they are used in various industrial fields such as automobiles, ships, aircraft, hydraulic equipment, general machinery industry, pollution-related departments, etc. Are widely used as O-rings, gaskets, oil seals, diaphragms, hoses, rolls, sheet materials and the like. However, fluorinated rubber vulcanizates have poor tensile strength, so when used as packing for household coolers, car air conditioners, refrigerators, refrigerators, etc., cracks will occur if the pressure changes rapidly while still swollen by freon. In many cases, problems occur with the sealability.

[Problems to be Solved by the Invention]

The object of the present invention is to achieve extremely high tensile strength, and compression set resistance similar to conventional fluororubber vulcanizates,
It is an object of the present invention to provide a fluororubber vulcanization composition which gives a vulcanizate having excellent heat resistance, oil resistance and chemical resistance, and has excellent vulcanization characteristics that can be easily cured.

[Means for Solving the Problems] As a result of intensive studies by the present inventors, an organic peroxide,
It has been found that a composition prepared by blending a co-crosslinking agent and a specific carbon black with a specific fluorine-containing elastomer meets the above-mentioned object, and based on this finding, the present invention has been completed.

That is, the present invention comprises 1. (A) a vinylidene fluoride unit and at least one fluorine-containing monomer, and iodine or bromine-containing intrinsic viscosity (ml / g) in the range of 50 to 100. Fluoroelastomer copolymer, (B) organic peroxide, (C) co-crosslinking agent, (D) average particle size 30 to 35 μm, surface area 70 to 80 m ² / g, oil absorption 1.2 to 1.5 ml / g, pH 7. A fluororubber vulcanizing composition containing 0 to 7.7 carbon black.

Furthermore, as a preferred embodiment of the present invention, 2. The fluoroelastomer vulcanization composition according to the above 1, wherein the fluoroelastomer copolymer contains 40 to 85 mol% of vinylidene fluoride units. The fluororubber vulcanizate according to claim 1, wherein the polymer comprises vinylidene fluoride units and at least one fluorine-containing monomer, and the iodine-containing intrinsic viscosity (ml / g) is in the range of 50 to 100. Composition 4. The fluororubber vulcanization composition as described in the above item 1 in which the co-crosslinking agent is triallyl isocyanurate, etc. may be mentioned.

The fluorine-containing elastomer copolymer containing vinylidene fluoride units and at least one fluorine-containing monomer and containing iodine or bromine, which is used as the component (A) in the fluororubber vulcanizing composition of the present invention, is Kosho 54-1585
JP-B-63-41928 and JP-A-60-221409.

Examples of the at least one fluorine-containing monomer unit include hexafluoropropene, pentafluoropropene, tetrafluoroethylene, trifluoroethylene,
Chlorotrifluoroethylene, dichlorodifluoroethylene, bromotrifluoroethylene, 4-bromo-3,3,
4,4-tetrafluorobutene-1, fluorinated vinyl ethers, fluorinated alkyl vinyl ethers and the like can be mentioned. Intrinsic viscosity (ml / g) of this fluorine-containing elastomer
Is in the range of 50 to 100 when the intrinsic viscosity (ml / g) is less than 50, the high tensile strength, which is the object of the present invention, cannot be obtained.
This is because if it exceeds 0, a sufficient crosslink density cannot be obtained and the compression set is deteriorated.

In addition, examples of the fluorine-containing elastomer copolymer of the component (A) include vinylidene fluoride-hexafluoropropene copolymer, vinylidene fluoride-hexafluoropropene-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoro. Propene-tetrafluoroethylene-4-bromo-3,3,4,4-tetrafluorobutene-1
Examples thereof include copolymers.

During vulcanization molding of these copolymers, it is known that the organic peroxide decomposed by heating removes iodine or bromine in the polymer to form a radical, which is mediated by a co-crosslinking agent to crosslink.

As an example of the organic peroxide as the component (B), any organic peroxide capable of generating a peroxide radical under vulcanization conditions may be used.
For example, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5
-Dihydroxy peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, a, a'-bis (t-butylperoxy) -p-
Diisopropylbenzene, 2,5-dimethyl-2,5-di (t
-Butylperoxy) hexyne, 2,5-dimethyl-2,5-
Di (t-butylperoxy) hexyne-3, benzoyl peroxide, t-butylperoxybenzene, 2,5-
Examples thereof include dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butyl-oxyisopropyl carbonate and the like.

Examples of the co-crosslinking agent as the component (C) include triallyl cyanurate, triallyl isocyanurate, trimethallyl isocyanurate, triacrylic formal, triallyl trimellitate, N, N'-m-phenylene bismaleimide, diallyl. Phthalate, tetraallyl terephthalamide, tris (diallylamine) -s-triazine,
Examples thereof include triallyl phosphite, N, N-diallyl acrylamide and the like, and a particularly preferable co-crosslinking agent is triallyl isocyanurate.

The carbon black of component (D) has an average particle size of 30 to 35 μm.
m, surface area 70-80 m ² / g, oil absorption 1.2-1.5 ml / g, pH 7.0-
7.7, for example MAF carbon black.
Product names of MAF carbon black include Tokai Carbon Co., Ltd. product “Seast 116” and Asahi Carbon Co., Ltd. product “Asahi # 60H”.

Regarding the compounding ratio of each of the above components in the fluororubber vulcanizing composition of the present invention, usually 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, of (B) component, relative to 100 parts by weight of (A) component, ( Component (C) is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, and component (D) is 1 to 50 parts by weight, preferably 5 to 30 parts by weight. The reason why the component (B) is in this range is that if the amount is less than 0.1 parts by weight, a sufficient curing rate cannot be obtained, and if it exceeds 5, the normal physical properties of the vulcanizate are deteriorated. The range is because if less than 0.1 part by weight, a uniform vulcanized product cannot be obtained, and if it exceeds 10 parts by weight, the physical properties of the vulcanized product deteriorate, and the component (D) is in this range. Is
This is because if it is less than 1 part by weight, high tensile strength cannot be obtained, and if it exceeds 50 parts by weight, the properties of the vulcanizate as an elastic body are significantly deteriorated.

Further, in the fluororubber vulcanizing composition of the present invention, if necessary, other components such as carbon black, silica, clay, diatomaceous earth, calcium carbonate, calcium fluoride, barium sulfate, etc., other than those claimed in the present invention, Fillers, processing aids, plasticizers, colorants, and acid acceptors such as magnesium oxide, lead oxide and calcium oxide may be added. 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 fluororubber vulcanization composition thus obtained is vulcanized according to a conventional method. Examples of this vulcanization method include a method in which after kneading with an open-type kneading roll or a closed-type kneading roll (Banbury mixer, pressure kneader, etc.), the mixture is put into a mold and pressurized to perform primary vulcanization, and then secondary vulcanization. To be
Generally, the conditions for primary vulcanization are a temperature of 120 to 20 ° C and a time of 3
The range of 180 to 180 minutes and the pressure of 20 to 150 kg / m ^{2 and} the range of the temperature of 120 to 250 ° C. and the 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. It is also possible to use a method in which a solution or dispersion liquid as a medium is prepared, and then the surface of a paper, fiber, filter, sheet, plate, tube, pipe, tank, large container or other molded article is coated and vulcanized. it can.

The fluororubber vulcanization composition of the present invention achieves extremely high tensile strength, and, like the conventional fluororubber vulcanizates, is vulcanized with excellent compression set resistance, heat resistance, oil resistance, and chemical resistance. It has excellent vulcanization characteristics that give a product and can be easily cured. Therefore, it can be widely used as O-rings, gaskets, oil seals, diaphragms, hoses, rolls, sheet materials, etc. in various industrial fields such as automobiles, ships, aircraft, hydraulic equipment, general machinery industry, and pollution-related departments. , A household cooler that comes into contact with Freon, which had been previously restricted in the use of fluororubber vulcanizates,
It can be used as packing for car air conditioners, refrigerators, refrigerators, etc., and has an extremely high industrial value.

〔Example〕

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

The hardness of the vulcanized product was measured according to JIS-A, 100% tensile stress, tensile strength, elongation, compression set JIS K 6301. The intrinsic viscosity (ml / g) was measured at 35 ° C. using a capillary viscometer by dissolving a fluoroelastomer in methyl ethyl ketone to prepare a 0.1 ml / g concentration solution.

Further, the characteristics of carbon black were determined by the following measuring methods. That is, the average particle size is measured by an electron microscope (ASTM D 176
5), surface area is ASTM D 3037, pH is JIS K 6221 6.4.2, oil absorption is JIS K 6221 6.1.2A method.

Example 1 The composition has a vinylidene fluoride unit of 65 mol%, a hexafluoropropene unit of 15 mol%, and a tetrafluoroethylene unit.
100 parts by weight of a fluorine-containing elastomer having 20 mol%, an intrinsic viscosity of 72 ml / g and an iodine content of 2000 ppm was wound around an open-type kneading roll, and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane was wrapped around this. After kneading 1.5 parts by weight, 3 parts by weight of triallyl isocyanurate, and 10 parts by weight of SAST 116, the mixture was left to stand overnight for aging.

Then, after kneading again, put it in the mold and
Press vulcanization was performed at ℃ for 10 minutes, and formed into a sheet and a JIS cylinder.

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 and compression set resistance of the vulcanized molded product thus obtained.

Example 2 A vulcanized molded product was prepared and various tests were carried out in the same manner as in Example 1 except that the amount of the cast 116 was changed to 15 parts by weight. The results are shown in Table 1.

Example 3 A vulcanized molded product was prepared and various tests were conducted in the same manner as in Example 1 except that the compounding amount of the cast 116 was changed to 20 parts by weight. The results are shown in Table 1.

Example 4 A vulcanized molded product was prepared and various tests were carried out in the same manner as in Example 1 except that the amount of the cast 116 was 30 parts by weight and the press vulcanization time was 12 minutes. The results are shown in Table 1.

Example 5 The composition has a vinylidene fluoride unit of 55 mol%, a hexafluoropropene unit of 25 mol%, and a tetrafluoroethylene unit.
A vulcanized molded product was prepared and various tests were conducted in the same manner as in Example 3 except that 20 mol%, an intrinsic viscosity of 52 ml / g and an iodine content of 1600 ppm were used. The results are shown in Table 1.

Comparative Example 1 Composition: Vinylidene fluoride unit 65 mol%, Hexafluoropropene unit 15 mol%, Tetrafluoroethylene unit
A vulcanized molded product was prepared and various tests were conducted in the same manner as in Example 3 except that a fluorine-containing elastomer having 20 mol%, an intrinsic viscosity of 48 ml / g and an iodine content of 4200 ppm was used. The results are shown in Table 1.
Shown in

Comparative Example 2 Tokai Carbon Co., Ltd. product Seast S (SRF carbon black, average particle size 58 to 94 μm, instead of Seast 116,
Surface area 25-30 m ² / g, oil absorption 0.7-0.9 ml / g, pH 7.5-9.0)
A vulcanized molded product was prepared and various tests were conducted in the same manner as in Example 1 except that 15 parts by weight was compounded. The results are shown in Table 1.

Comparative Example 3 20 parts by weight of Cyanmax's product THERMAX (MT carbon black average particle size 450 to 556 μm, surface area 5 to 7 m ² / g, oil absorption 0.3 to 0.5 ml / g, pH 9 to 11) was blended instead of Seast 116. A vulcanized molded product was prepared and various tests were carried out in the same manner as in Example 1 except that the above was performed. The results are shown in Table 1.

[Effects of the Invention] The fluororubber vulcanization composition of the present invention achieves extremely high tensile strength, and has compression set resistance, heat resistance, oil resistance, and chemical resistance similar to conventional fluororubber vulcanizates. It has excellent vulcanizate properties and can be easily cured.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-63-308008 (JP, A) JP-A-61-55138 (JP, A) JP-A-56-86948 (JP, A) JP-A-54- 129049 (JP, A)

Claims (1)

(57) [Claims] 1. A fluorine-containing elastomer comprising (A) a vinylidene fluoride unit and at least one fluorine-containing monomer and containing iodine or bromine and having an intrinsic viscosity (ml / g) in the range of 50 to 100. Copolymer, (B) organic peroxide,
(C) Co-crosslinking agent, (D) Average particle size 30 to 35 μm, surface area 70
A fluororubber vulcanizing composition containing carbon black having a viscosity of -80 m ² / g, an oil absorption of 1.2-1.5 ml / g and a pH of 7.0-7.7.