JPH05186654A - Readily curable fluorine-containing elastomer vulcanizable composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition useful for O-rings, gaskets, etc., of automobile, etc., having excellent tensile characteristics, heat resistance, oil resistance and sealability, comprising a specific fluorine-containing elastomer polymer, an organic peroxide and a co-cross-linking agent. CONSTITUTION:The objective composition comprising (A) 100 pts.wt. fluorine- containing elastomer polymer which consists of (i) a vinylidene fluoride unit, (ii) a hexafluoropropylene unit and optionally (iii) <=35wt.% tetrafluoroethylene unit, has a ratio of the component (i) and (ii) of 40/60 to 80/20 by weight and 70-90ml/g intrinsic viscosity, contains 0.05-1wt.% bonded iodine at molecular chain end and is vulcanizable with an organic peroxide, (B) preferably 0.1-5 pts.wt. organic peroxide and (C) preferably 0.1-10 pts.wt. co-cross-linking agent such as triallyl cyanurate.

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 equivalent to conventional fluorinated elastomer vulcanizates without secondary vulcanization.
The present invention relates to a fluorine-containing elastomer vulcanizing composition that exhibits oil resistance, sealability and the like and is easily cured.

[0002]

2. Description of the Related Art Fluorine-containing elastomer vulcanizates have excellent heat resistance and oil resistance, so that they are used in various industrial fields such as automobiles, ships, aircraft, hydraulic equipment, general machinery industry, and pollution-related industries. It is used for O-rings, gaskets, oil seals, diaphragms, hoses, rolls, sheet materials, etc. in departments and the like. However, in order to bring out these excellent properties, a temperature of 180 to 26
Secondary vulcanization at 0 ° C. for 4 to 24 hours is indispensable, which is a serious problem from the viewpoint of energy saving, productivity and economic efficiency. Therefore, there is a strong demand for a transition to non-post-curing, which has the same performance as the secondary vulcanized product without performing secondary vulcanization. However, non-post cure of the fluorinated elastomer vulcanizate has not yet been realized.

[0003]

The object of the present invention is to obtain excellent tensile properties, heat resistance, oil resistance, sealability, etc. equivalent to those of conventional fluorinated elastomer vulcanizates without secondary vulcanization. It is to provide a fluorine-containing elastomer vulcanizing composition that develops and is easy to cure.

[0004]

As a result of intensive studies, the inventors of the present invention have found that a vulcanized composition comprising a specific fluorine-containing elastomer vulcanizable with an organic peroxide can meet the above object. The present invention has been completed based on this finding. That is, the present invention relates to (a) (a) vinylidene fluoride unit (hereinafter referred to as VdF), (b) hexafluoropropylene unit (hereinafter referred to as HFP) and optionally (c) 35 wt% or less of tetrafluoroethylene unit (hereinafter referred to as " TFE), the weight ratio of (a) unit to (b) unit is 40:60 to 80:20, the intrinsic viscosity is in the range of 70 to 90 ml / g, and 0.05 at the end of the molecular chain. A fluorine-containing elastomer vulcanization composition comprising a fluorine-containing elastomer copolymer vulcanizable with an organic peroxide containing 1 to 1% by weight of bound iodine, (b) an organic peroxide, and (c) a co-crosslinking agent. Is provided.

The fluorine-containing elastomer used as the component (a) in the fluorine-containing elastomer vulcanizing composition of the present invention is (a) VdF and (b) HFP and, in some cases, (c).
It is composed of 35% by weight or less of TFE, the weight ratio of (a) unit to (b) unit is 40:60 to 80:20, and the intrinsic viscosity is in the range of 70 to 90 ml / g. It is essential that it contain 0.05 to 1% by weight of bound iodine and be vulcanizable with organic peroxides. When iodine is bonded to the end of the molecular chain of the fluorine-containing elastomer, the peroxide is easily desorbed by peroxide during vulcanization to form a radical in the polymer chain, and this radical serves as a crosslinking point. Since iodine is easily desorbed in this manner, the fluorinated elastomer of the present invention has a fast vulcanization rate and is easily cured. As a method of introducing iodine into the molecular chain end of the fluorine-containing elastomer, a method of using an iodine compound as a chain transfer agent (Japanese Patent Publication No. 63-41928, JP-A No. 60-29928).
No. 221409) is effective. Examples of the chain transfer agent include monoiodomethane, 1-iodomethane, 1-
Iodo-n-propane, isopropyl iodide, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-
Perfluoro iodides in which all hydrogen atoms of n-propane and these compounds are replaced with fluorine atoms are preferably used. The content of iodine in the fluorine-containing elastomer is 0.05 to 1% by weight, preferably 0.1 to 0.1% by weight based on the total amount of VdF, HFP, TFE and iodine.
A range of 0.5% by weight is chosen. If this amount is less than 0.05% by weight, the distance between crosslink points becomes too long, and the crosslink density is significantly reduced, leading to the occurrence of mold sticking and deterioration of compression set. If it exceeds 1% by weight, the distance between crosslink points is increased. Is too short, and it tends to be difficult to obtain a satisfactory elastic body. Furthermore, the intrinsic viscosity of the fluorine-containing elastomer is 70 to 90 ml.
In the range of / g, the intrinsic viscosity is less than 70 ml / g, good mechanical properties and compression set resistance cannot be obtained only by the primary vulcanization, and only the primary vulcanization is obtained when the intrinsic viscosity exceeds 90 ml / g. This is because the compression set resistance is poor.

As the organic peroxide as the component (b), any organic peroxide capable of generating a peroxide radical under vulcanizing conditions may be used, for example, 1,1-bis (t-butylperoxy).
-3,5,5-Trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-
Bis (t-butylperoxy) octane, n-butyl 4,4-bis (t-butylperoxy) valerate,
2,2-bis (t-butylperoxy) butane, 2,5
-Dimethylhexane-2,5-dihydroxy peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, α, α'-bis (t-butylperoxy-m-isopropyl) benzene 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-
Butylperoxy) hexyne-3, benzoyl peroxide, t-butylperoxybenzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t
-Butyl peroxy maleic acid, t-butyl-oxy isopropyl carbonate, etc. are mentioned.

Examples of the co-crosslinking agent as the component (c) include 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. A particularly preferable co-crosslinking agent is triallyl isocyanurate.

The blending ratio of each of the above components in the fluorinated elastomer vulcanizing composition of the present invention is usually (a)
0.1 to 5 parts by weight of component (b), preferably 0.5 to 3 parts by weight, and 0.1 to 100 parts by weight of component (c).
It is 10 parts by weight, preferably 0.5 to 5 parts by weight. The component (b) of the present invention is in this range because if it is less than 0.1 parts by weight, a sufficient curing rate cannot be obtained, and if it is 5 parts by weight or more, the physical properties of the vulcanized product deteriorate. The reason why the component (c) is in this range is that a uniform vulcanizate is not obtained when the amount is less than 0.1 parts by weight, and the normal physical properties of the vulcanizate are deteriorated when the amount is 10 parts by weight or more.

Further, in the fluorine-containing elastomer vulcanizing 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, phosphoric acid ester, higher fatty acid ester, low molecular weight polyethylene, silicone oil, silicone grease, metal soap, stearic acid, calcium stearate, sodium stearate, fatty amine, titanium white, red iron oxide Fillers such as, processing aids, plasticizers, colorants, etc. can be blended, and as acid acceptors, for example, lead oxide, ferric phosphite, magnesium oxide, zinc oxide, calcium oxide, calcium hydroxide. , Hydrotal Ito compound or the like may be blended. Further, within a range not departing from the gist of the present invention,
One or two kinds of conventionally known vulcanizing agents and vulcanization accelerators may be blended.

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 it in a mold. A method of pressurizing and vulcanizing can be mentioned. Generally, a temperature of 12 is used as the vulcanization condition.
0 to 200 ° C, time 1 to 180 minutes, pressure 20 to 150k
A range of g / m ² is adopted. As other vulcanizing means, a method of vulcanizing after preforming such as injection or extrusion, or one or more of ketones such as methyl ethyl ketone and acetone, ethers such as ethyl ether and tetrahydrofuran, and the like are 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 paper, fiber, film, sheet, plate, tube, pipe, tank, large container or other molded article is coated and vulcanized. it can.

[0011]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. The properties of the fluorinated elastomer and the physical properties of the vulcanized product were determined by the methods described below.

(1) Composition of Monomer Unit After the fluorine-containing elastomer was dissolved in acetone, ¹⁹ F-NMR was used.
(Hitachi measurement R-24F type). (2) Intrinsic viscosity 0.1 g / 100 ml using methyl ethyl ketone as solvent
Was measured at 35 ° C. using a capillary viscometer.

(3) Iodine Content in Fluorine-Containing Elastomer It was measured by a fluorescent X-ray method (System 3070 manufactured by Rigaku Denki Kogyo). (4) Hardness [JIS-A], 100% tensile stress, tensile strength, and elongation of the vulcanized product were measured according to JIS-K6301. (5) The compression set is JIS-K6301 under the condition of 200 ° C. × 72 hours using an O-ring of size P-24.
It was measured according to.

(6) The heat aging test was carried out according to JIS-K6301 under the condition of 230 ° C. × 72 hours. (7) For the oil resistance test, the lubricating oil No. 175 ℃ × 3 using oil
It was measured according to JIS-K6301 under the condition of 72 hours.

[0015]

[Reference Example 1] An autoclave with an internal volume of about 50 liters equipped with an electromagnetic induction stirrer was sufficiently scavenged with nitrogen gas, and depressurization-nitrogen filling was repeated 3 times to replace nitrogen, and then deoxygenated under reduced pressure. 24 kg of purified water, 370 g of 1,1,2-trichloro-1,2,2-trifluoroethane, 24 g of methyl cellulose (viscosity 50 cp) as a suspension stabilizer
And charged with 33 g of diiodomethane as a chain transfer agent,
The temperature was kept at 50 ° C. with stirring at 475 rpm. Then 15.5 wt% VdF, 78 wt% HFP and TF
24 kg / cm of mixed monomer consisting of 6.5 wt% E
^I prepared until ²・ G. Next, 5 g of diisopropyl peroxydicarbonate as a catalyst was pressed in to initiate polymerization. When the pressure was reduced to 23.5 kg / cm ² · G by polymerization, a mixed monomer consisting of VdF 47.5% by weight, HFP 31.5% by weight and TFE 21% by weight was added, and the pressure was returned to 24 kg / cm ² · G. It was Such an operation was repeated to carry out a polymerization reaction for 10.6 hours. After the completion of the polymerization reaction, the remaining mixed monomer was scavenged, the obtained suspension was dehydrated with a centrifuge, and thoroughly washed with water, and then 1
Fluorine-containing elastomer about 5.8k after vacuum drying at 00 ℃
g was obtained. The obtained fluorine-containing elastomer is VdF4
It was 7.5% by weight, 31.5% by weight of HFP and 21% by weight of TFE, and the intrinsic viscosity was 50 ml / g. Also,
The iodine content in the fluorinated elastomer was 0.5% by weight.

[0016]

[Reference Example 2] Polymerization reaction was carried out for 13 hours in the same manner as in Reference Example 1 to obtain 8.6 kg of a fluoroelastomer. The obtained fluorine-containing elastomer had VdF of 47.5% by weight and H
The FP was 31.5% by weight and the TFE was 21% by weight, and the intrinsic viscosity was 65 ml / g. The iodine content in the fluorine-containing elastomer was 0.26% by weight.

[0017]

[Reference Example 3] A polymerization reaction was carried out in the same manner as in Reference Example 14 for 14 hours to obtain 10.5 kg of a fluorine-containing elastomer. The resulting fluorine-containing elastomer had VdF of 47.5% by weight,
The HFP was 31.5% by weight and the TFE was 21% by weight, and the intrinsic viscosity was 75 ml / g. The iodine content in the fluorine-containing elastomer was 0.18% by weight.

[0018]

[Reference Example 4] Polymerization reaction was carried out for 16 hours in the same manner as in Reference Example 1 to obtain 12.7 kg of a fluorine-containing elastomer. The resulting fluorine-containing elastomer had VdF of 47.5% by weight,
HFP was 31.5% by weight and TFE was 21% by weight, and the intrinsic viscosity was 85 ml / g. The iodine content in the fluorinated elastomer was 0.16% by weight.

[0019]

[Reference Example 5] Polymerization reaction was carried out in the same manner as in Reference Example 1 for 17.5 hours to obtain 15.4 kg of a fluorine-containing elastomer. The fluoroelastomer obtained had VdF of 47.5% by weight, HFP of 31.5% by weight and TFE of 21% by weight, and an intrinsic viscosity of 95 ml / g. The iodine content in the fluorine-containing elastomer was 0.14% by weight.

[0020]

Example 1 100 parts by weight of the fluorine-containing elastomer of Reference Example 3 was wrapped around an open type kneading roll, 30 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. Knead the department.
Next, after kneading 4 parts by weight of triallyl isocyanurate "TAIC" manufactured by Nippon Kasei Co., Ltd. and 1.5 parts by weight of organic peroxide "Perhexa 25B" manufactured by NOF CORPORATION, the mixture was left to stand overnight for aging. It was

Then, after kneading again, it is put in a mold,
Press vulcanization was performed at a temperature of 160 ° C. for 10 minutes to form a sheet, and various tests were conducted.

[0022]

Example 2 A vulcanized molded product was prepared and various tests were conducted in the same manner as in Example 1 except that the fluorinated elastomer of Reference Example 4 was used instead of the fluorinated elastomer of Reference Example 3.

[0023]

[Comparative Example 1] The fluorine-containing elastomer of Reference Example 1 was used in place of the fluorine-containing elastomer of Reference Example 3, press vulcanization was performed, and heating was further performed for 4 hours in an air circulation type furnace at a temperature of 180 ° C. Vulcanized molded products were prepared and various tests were conducted in the same manner as in Example 1 except that secondary vulcanization was performed.

[0024]

Comparative Example 2 A vulcanized molded product was prepared and various tests were conducted in the same manner as in Comparative Example 1 except that the fluorine-containing elastomer of Reference Example 2 was used instead of the fluorine-containing elastomer of Reference Example 1.

[0025]

Comparative Example 3 A vulcanized molded product was prepared and various tests were conducted in the same manner as in Comparative Example 1 except that the fluorinated elastomer of Reference Example 5 was used in place of the fluorinated elastomer of Reference Example 1. The above results are summarized in Table 1. Examples 1 and 2 have only primary vulcanization, and show the same normal state physical properties, compression set resistance, heat resistance, and oil resistance as those obtained when the secondary vulcanization of Comparative Examples 1, 2, and 3 were performed.

[0026]

[Table 1]

[0027]

EFFECT OF THE INVENTION Since the vulcanized composition of the specific fluorine-containing elastomer of the present invention can be easily cured only by the primary vulcanization, the obtained vulcanized product is obtained by using the conventionally known fluorine-containing elastomer vulcanized composition. Excellent normal physical properties equivalent to those of secondary vulcanization,
It has compression set resistance, heat resistance, and oil resistance. Therefore, the industrial value of the present invention, which does not require secondary vulcanization, is extremely high in terms of energy saving, productivity and economic efficiency.

Claims (2)

[Claims] 1. A composition comprising (a) (a) vinylidene fluoride unit, (b) hexafluoropropylene unit and optionally (c) 35 wt% or less of tetrafluoroethylene unit, and (a) unit and (b) Unit weight ratio is 40:
60 to 80:20 and an intrinsic viscosity of 70 to 90 m
It is in the range of 1 / g and 0.05 to 1% by weight at the end of the molecular chain.
A fluorine-containing elastomer copolymer vulcanizable with an organic peroxide containing bound iodine, (b) an organic peroxide,
(C) A fluorine-containing elastomer vulcanizing composition which is easy to cure and which comprises a co-crosslinking agent. 2. (b) per 100 parts by weight of component (a)
The fluorine-containing elastomer vulcanizing composition according to claim 1, wherein the components are 0.1 to 5 parts by weight and the component (c) is 0.1 to 10 parts by weight.