JP3533750B2 - Fluoro rubber composition - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a fluororubber composition. More specifically, the present invention relates to a fluororubber composition having excellent vulcanization adhesion to metals and the like.

[0002]

2. Description of the Related Art A vulcanized product of fluororubber has excellent properties such as heat resistance, chemical resistance, oil resistance, and weather resistance. Therefore, it is used as a sealing material for gaskets, O-rings, oil seals, packings, etc. Widely used in such fields as automobile industry, hydraulic industry, general machinery industry and aircraft industry. Among these sealing materials, vulcanization adhesion of fluororubber and metal is required to manufacture oil seals, etc. Generally, a silane coupling agent or the like is applied and baked on a phosphate-treated mild steel plate. However, the unvulcanized fluororubber compound is vulcanized under pressure.

Regarding improvement of vulcanization adhesion of fluororubber to metal, JP-A-3-37251 discloses vinylidene fluoride-tetrafluoroethylene-hydrocarbon olefin terpolymer copolymer gum, polyhydroxy compound, organic compound. Fluorinated elastomeric compositions comprising an onium compound and a fluorinated aliphatic sulfonyl compound adhesion promoter are described. Examples of the fluoroaliphatic sulfonyl compound adhesion promoter exclusively formula RfSO ₂ NH
Perfluoroalkyl-N-substituted sulfonamides represented by R are used.

However, in the vinylidene fluoride-hexafluoropropene copolymer, perfluoroalkyl is used as an adhesion promoter for adhering it to a metal.
When using -N-alkylsulfonamide,
If sufficient adhesion is not obtained and the amount of the adhesion promoter used is increased in order to increase the adhesion, the elongation value will decrease significantly, and the elongation characteristics of the rubber may not be sufficiently secured. Do you get it.

[0005]

The object of the present invention is to provide a fluororubber comprising a vinylidene fluoride-hexafluoropropene copolymer or a vinylidene fluoride-hexafluoropropene-tetrafluoroethylene terpolymer in which they are An object of the present invention is to provide a fluororubber composition having improved adhesiveness to a metal or the like without substantially deteriorating the elongation property of the rubber originally possessed.

[0006]

The object of the present invention is as follows.
The above fluororubber and the general formula RfCONHR (where:
Rf is a perfluoroalkyl group having 4 to 12 carbon atoms, R represents a phenyl group, a trifluoromethylphenyl group or a phenethyl group) N- substituted acid represented by Ami
This is achieved by a fluororubber composition containing a compound.

As a fluororubber to be adhered to a metal or the like, a vinylidene fluoride-hexafluoropropene copolymer or hexafluoro in which hexafluoropropene is copolymerized in an amount of about 10 to 30 mol%, preferably about 15 to 25 mol%. About 5 to 30 mol% of propene, preferably about 1
5 to 25 mol% and tetrafluoroethylene of about 0.1
A vinylidene fluoride-hexafluoropropene-tetrafluoroethylene terpolymer copolymerized with 35 mol%, preferably about 5 to 25 mol%, is used.

These are capable of amine vulcanization and polyol vulcanization, or peroxide vulcanization in the presence of a co-crosslinking agent, and all of these vulcanization methods are known and used. A cross-linking agent depending on the sulfurizing method is used. That is, as a crosslinking agent for amine vulcanization, 4,4'-
Methylenebis (cyclohexylamine) carbamate, hexamethylenediaminecarbamate, N, N'-dicinnamylidene-1,6-hexanediamine, etc. are used, and the crosslinking agent for polyol vulcanization is 2,2-bis (4-hydroxyphenyl) Propane [bisphenol A], 2,2-bis (4-hydroxyphenyl) perfluoropropane [bisphenol
AF], hydroquinone, catechol, resorcin, 4,4'-
Dihydroxydiphenyl, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylsulfone, 2,
A polyhydroxy aromatic compound such as 2-bis (4-hydroxyphenyl) butane or an alkali metal salt or an alkaline earth metal salt thereof is used, and these crosslinking agents are about 0.5 to 10 parts by weight per 100 parts by weight of fluororubber. , Preferably about
It is used in a proportion of 1 to 5 parts by weight. Further, as the co-crosslinking agent for peroxide vulcanization and the organic peroxide, any commonly used one can be used. The co-crosslinking agent is used in an amount of about 0.5 to 10 parts by weight, preferably about 0.5 to 6 parts by weight, per 100 parts by weight of the fluororubber, and the organic peroxide is
It is used in an amount of about 0.1 to 5 parts by weight, preferably about 0.5 to 3 parts by weight, per 100 parts by weight of fluororubber.

As the vulcanization accelerator, when a polyhydroxy aromatic compound or a metal salt thereof is used as a crosslinking agent, various quaternary ammonium salts or quaternary phosphonium salts are added per 100 parts by weight of fluororubber. It is used in a proportion of about 0.1 to 10 parts by weight, preferably about 0.1 to 2 parts by weight. As the acid acceptor, various divalent metal oxides or hydroxides are used in a ratio of about 1 to 20 parts by weight, preferably about 3 to 15 parts by weight, per 100 parts by weight of the fluororubber.

Further, an N-substituted acid ester as an adhesion promoter is used.
The amide compound can be easily synthesized by a condensation reaction between a perfluorocarboxylic acid halide and aniline, trifluoromethylaniline or phenethylamine. This condensation reaction is carried out at a reaction temperature of room temperature to about 110 ° C. when using, for example, C ₇ F ₁₅ COF. These acid amide compounds are used in an amount of about 0.05 to 1 part by weight, preferably about 0.05 to 0.5, per 100 parts by weight of the fluororubber.
Used in proportions by weight. At usage rates below this,
The adhesive strength aimed at by the present invention cannot be obtained between a metal and the like, and on the other hand, if it is used in a ratio higher than this, the decrease in elongation value becomes large, which is not preferable.

The composition is prepared by appropriately adding at least one of carbon black, silica, graphite, clay, talc, diatomaceous earth, barium sulfate, titanium oxide and the like as a filler or a reinforcing agent and other necessary compounding agents. However, the kneading is performed by a general kneading means such as a mixing roll. At this time, bisphenol
The addition of a cross-linking agent such as AF is preferably performed at a later point in time. The prepared composition is vulcanized by bonding the fluororubber composition to a metal, preferably a metal which has been treated with a primer, and then generally press vulcanization (primary vulcanization) and oven vulcanization (secondary vulcanization). However, injection molding is also possible.

[0012]

The vinylidene fluoride-hexafluoropropene copolymer or the vinylidene fluoride-hexafluoropropene-tetrafluoroethylene terpolymer is a vinylidene fluoride-hexafluoropropene-based fluororubber with an N-substituent When an N-substituted acid amidation compound in which is a phenyl group, a trifluoromethylphenyl group or a phenethyl group is added as an adhesion promoter, compared with the case where a perfluoroalkyl-N-alkylsulfonamide is added. It has excellent vulcanization adhesiveness at the same addition ratio,
Therefore, it is possible to add in a smaller amount, and it is possible to effectively reduce the decrease in elongation.

[0013]

EXAMPLES The present invention will now be described with reference to examples.

Examples 1 to 3 Fluororubber A 100 parts by weight Vinylidene fluoride-hexafluoropropene (molar ratio 78:22) copolymer MT carbon black 20 〃 lead oxide 15 〃 4,4'-methylenebis (cyclohexylamine) Carbamate 2 〃 N- (m-trifluoromethylphenyl) perfluorooctanoic acid amide 0.1 〃 (Example 1) N-phenyl perfluorooctanoic acid amide 0.1 〃 (Example 2) N-phenethyl perfluorooctane Acid amide 0.1 〃 (Example 3) The above components were kneaded with an 8-inch mixing roll, and the kneaded product was subjected to press vulcanization at 180 ° C for 5 minutes and oven vulcanization at 230 ° C for 22 hours. . In addition,
Among the acid amide compounds used, for example, perfluorohexyltrifluoromethylphenyl acid amide was synthesized as follows. In a three-necked flask equipped with a thermometer, a condenser and a stirrer, C ₇ F ₁₅ COF 20.8
g (0.05 mol) was charged, and 16.1 g (0.10 mol) of m-trifluoromethylaniline was added dropwise thereto over 10 minutes. During this time, the temperature rose from room temperature (15 ° C) to 95 ° C. After the dropping was completed, 50 ml of 2N hydrochloric acid was added and heated to 80 ° C. to dissolve the generated precipitate. 100 ml of diethyl ether was added at room temperature for extraction, and the ether layer was washed with water until pH 7 and then concentrated. By washing the concentrate with hydrochloric acid and extracting with ether, m-
Trifluoromethylaniline hydrofluoride CF ₃ C ₆ H ₄
By removing NH ₂ HF, the target product N- (m-triflu
22.7 g (yield 81.5%) of oromethylphenyl ) perfluorooctanoic acid amide was obtained.

The vulcanizates obtained were measured for the following items. Vulcanization physical properties: JIS K-6301 compliant Compression set: P-24 O-rings were compressed at 25% for 200 hours at 200 ° C. Further, metal adhesion was measured by the following method. Metal adhesion: 20 of commercial adhesive (Japan Unicar product AP-133)
A primer consisting of a wt% methanol solution is applied onto a phosphate-coated mild steel sheet, allowed to air-dry at room temperature for 30 minutes, and then baked at 150 ° C for 10 minutes, whereupon the kneaded product is Was adhered and pressure-vulcanized at 180 ° C. for 5 minutes. The rubber portion of this metal-fluorine rubber adhesive was grasped with pliers and peeled off, and the area ratio of the rubber remaining on the metal surface was determined and used as a measure of the metal adhesiveness.

Examples 4 to 6 Fluororubber A 100 parts by weight MT carbon black 25 〃 calcium hydroxide 5 〃 magnesium oxide 3 〃 bisphenol AF 2 〃 benzyltriphenylphosphonium chloride 0.4 〃 N- (m-trifluoromethylphenyl) ) Perfluorooctanoic acid amide 0.1 〃 (Example 4) N-phenyl perfluorooctanoic acid amide 0.1 〃 (Example 5) N-phenethyl perfluorooctanoic acid amide 0.1 〃 (Example 6) Kneading, vulcanization and measurement were carried out in the same manner as in Examples 1 to 3 using each of the compounding ingredients.

Examples 7 to 9 100 parts by weight of fluororubber B Vinylidene fluoride-hexafluoropropene-tetrafluoroethylene (molar ratio 68:16:16) terpolymer MT carbon black 20 〃 lead oxide 5〃 triallyl Isocyanurate (Nippon Kasei Product TAIC M-60) 5 〃 Organic peroxide (Nippon Oil Vessel Product Perhexa 25B-40) 2 〃 N- (m-trifluoromethylphenyl) perfluorooctanoic acid amide 0.1 〃 Example 7) N- phenylperfluorooctanoic acid amide 0.1 〃 (Example 8) N-phenethyl perfluorooctanoic acid amide 0.1 〃 (Example 9) Kneading, vulcanization and measurement were carried out in the same manner as in No. 3.

The measurement results in each of the above examples are shown in Table 1 below. Table 1 Actual measurement items 1 2 3 4 5 6 7 8 9 9 Hardness (JIS A) 70 71 71 70 70 71 75 75 75 100% Modulus (MPa) 4.1 3.9 3.6 5.2 5.1 4.8 6.6 6.5 6.2 Tensile strength ( MPa) 17.1 16.8 16.4 15.5 15.0 14.8 21.0 20.9 20.5 Elongation (%) 260 260 280 230 230 260 210 210 220 Compression set (%) 51 52 53 20 22 22 32 33 33 Remaining rubber area (%) 100 100 100 100 100 100 100 100 100

Comparative Examples 1 to 3 In Examples 1, 4 or 7, N- (m-trifluoro) was used.
Dimethylphenyl) perfluorooctanoic acid amide was not used. The measurement results are shown in Table 2 below.

Examples 10 to 12 In Example 4, N- (m-trifluoromethylphene)
Nyl) perfluorooctanoic acid amide is 0.
05 parts by weight (Example 10), 0.3 parts by weight (Example 1)
1) or 0.5 parts by weight (Example 12).
The measurement results are shown in Example 4 together with 0.1 part by weight.
It is shown in Table 3 below.

Comparative Examples 4 to 7 In Example 10, Example 4, Example 11 or Example 12, N- (m-trifluoromethylphenyl) peroxide was used.
Instead of fluorooctanoic acid amide, the same amount of perfluorooctyl-N-methylsulfonamide was used, respectively. The measurement results are shown in Table 4 below.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-7-196879 (JP, A) JP-A-6-157686 (JP, A) JP-A-2-281062 (JP, A) JP-A-3- 37251 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 27/16

Claims (2)

(57) [Claims] 1. A fluororubber comprising a vinylidene fluoride-hexafluoropropene copolymer or a vinylidene fluoride-hexafluoropropene-tetrafluoroethylene terpolymer and a general formula RfCONHR (where R
f is a perfluoroalkyl group having 4 to 12 carbon atoms,
R is a phenyl group, a trifluoromethylphenyl group or a phenethyl group), which is a fluororubber composition containing an N-substituted acid amidation compound. 2. The method according to claim 1, which is used for vulcanization adhesion with a metal.
The fluororubber composition described.