JP2825536B2 - Peroxide vulcanizable fluoroelastomer composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a peroxide-curable fluoroelastomer composition. More specifically, it relates to a fluorine-containing elastomer composition containing iodine and bromine in the molecule and a peroxide-curable fluorine-containing elastomer composition containing an organic peroxide.

[Conventional technology]

The organic peroxide crosslinking of the fluorinated elastomer is considered to be superior to conventional crosslinking methods such as polyol crosslinking and polyamine crosslinking because it gives a crosslinked product having excellent engine oil resistance and solvent resistance.

As a fluorine-containing elastomer crosslinked by an organic peroxide, those containing iodine and bromine, iodine or bromine in the molecule have been proposed by the present applicant and others (JP-A-62-232,407, 53). -125,491 JP, 60-221,409 JP, 59-20,310 JP, 62-26JP
0,807, 63-308,008, JP-B-54-1585, etc.).

For example, JP-A-63-308008 discloses the carbon black as a compounding agent for such a fluorine-containing elastomer,
It is described that silica, clay, talc, diatomaceous earth, barium sulfate and the like are added, but the compression set of the vulcanizate of a fluorine-containing elastomer to which these are added does not always show a sufficiently satisfactory value.

[Problems to be solved by the invention]

An object of the present invention is to improve the compression set of a vulcanizate,
An object of the present invention is to provide a fluorine-containing elastomer composition which can be peroxide-cured.

[Means for solving the problem]

The peroxide-curable fluorine-containing elastomer composition for achieving the object of the present invention contains a fluorine-containing elastomer containing iodine and bromine in the molecule, an organic peroxide, a polyfunctional compound and powdered activated carbon. And preferably further contains a sulfur-containing compound used as an additive for rubber.

As the fluorinated olefin constituting the main part of the fluorinated elastomer containing iodine and bromine in the molecule used in the present invention, those having 2 to 8 carbon atoms are preferably used, for example, vinylidene fluoride, tetrafluoro Ethylene, hexafluoropropene, pentafluoropropene, chlorotrifluoroethylene, methyl perfluorovinyl ether, ethyl perfluorovinyl ether, n- or iso-propyl perfluorovinyl ether, n-, iso- or tert-butyl perfluorovinyl ether, n -Or iso-amyl perfluorovinyl ether, perfluoro (methyl vinyl ether), perfluoro (ethyl vinyl ether), perfluoro (n- or iso-propyl vinyl ether),
At least one of perfluoro (n-, iso- or tert-butyl vinyl ether), perfluoro (n- or iso-amyl vinyl ether), perfluoro (propoxypropyl vinyl ether) and the like are mainly used. Vinyl chloride, trifluoroethylene, perfluorocyclobutene, perfluoro (methylcycloperopene), hexafluoroisobutene, 1,2,2
-Trifluorostyrene, perfluorostyrene and the like are also used.

These fluorinated olefins can also be used in the form of being copolymerized with an olefinic compound having 2 to 6 carbon atoms and / or a fluorinated diene having 4 to 8 carbon atoms.

Examples of the olefinic compound include those having 2 to 6 carbon atoms such as unsaturated vinyl esters such as ethylene, propylene, butene and vinyl acetate, and alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether. Copolymerize at a rate of 50 mol%.

Further, as the fluorine-containing diene, for example, perfluoro-1,3-butadiene, perfluoro-1,4-pentadiene, 1,1,2-trifluoro-1,3-butadiene, 1,1,2-
Trifluoro-1,4-pentadiene, 1,1,2,3,3-pentafluoro-1,4-pentadiene, perfluoro-1,7-octadiene, perfluorodivinyl ether, perfluorovinyl perfluoroallyl ether, Examples thereof include those having 4 to 8 carbon atoms such as vinyl perfluoroallyl ether and perfluorovinyl vinyl ether. These fluorinated dienes are preferably copolymerized so as to be present in the fluorinated elastomer at a ratio of about 1 mol% or less. If copolymerization is carried out at a higher ratio, gelation of the copolymer elastomer becomes remarkable, and processability (flow characteristics)
And the elongation of the vulcanizate becomes worse.

Specific fluorinated olefin copolymers include hexafluoropropene-vinylidene fluoride copolymer, hexafluoropropene-vinylidene fluoride-tetrafluoroethylene terpolymer, and tetrafluoroethylene-vinylidene fluoride-perfluorocopolymer. (Methyl vinyl ether) terpolymer, tetrafluoroethylene-vinylidene fluoride-perfluoro (propyl vinyl ether) 3
Copolymer, tetrafluoroethylene-perfluoro (propoxypropyl vinyl ether) copolymer, tetrafluoroethylene-perfluoro (methyl vinyl ether) copolymer, tetrafluoroethylene-propylene copolymer, tetrafluoroethylene-vinylidene fluoride -Hexafluoropropene-pentafluoropropene 4
Terpolymer, tetrafluoroethylene-hexafluoropropene-vinylidene fluoride-perfluoro (methyl vinyl ether) quaternary copolymer, tetrafluoroethylene-hexafluoropropene-hexafluoroisobutene terpolymer, tetrafluoroethylene- Cyclohexyl vinyl ether copolymer, hexafluoropropene
Vinylidene fluoride-chlorotrifluoroethylene terpolymer, vinylidene fluoride-tetrafluoroethylene-
Methyl perfluorovinyl ether terpolymer, vinylidene fluoride-tetrafluoroethyl-n-butyl perfluorovinyl ether terpolymer, vinylidene fluoride-methyl perfluorovinyl ether-perfluoro (methyl vinyl ether) terpolymer Terpolymer, tetrafluoroethylene-methyl perfluorovinyl ether-perfluoro (methyl vinyl ether) terpolymer, vinylidene fluoride-hexafluoropropene-tetrafluoroethylene-methyl perfluorovinyl ether quaternary copolymer, tetrafluoroethylene-n- Butyl perfluorovinyl ether-perfluoro (methyl vinyl ether) terpolymer, vinylidene fluoride-n-butyl perfluorovinyl ether copolymer, tetrafluoroethylene-propylene -n- butyl perfluorovinyl ether terpolymer, tetrafluoroethylene - vinylidene fluoride - propylene -n- butyl perfluorovinyl ether quaternary copolymer and the like.

The polymerization reaction is carried out by solution polymerization, suspension polymerization or emulsion polymerization of a fluorine-containing olefin or the above-mentioned comonomer and the above-mentioned comonomer by a conventionally known method.

When an iodine-containing bromine compound is allowed to coexist during this polymerization reaction, iodine and bromine are introduced into the fluorinated olefin copolymer to form a crosslinking point at the time of organic peroxide crosslinking.

The iodine and bromine-containing compounds of the general formula RBr _n I _m (R: fluorohydrocarbon group, chlorofluorohydrocarbons group, chlorohydrocarbon group or a hydrocarbon group, n, m: 1 or 2) saturated or unsaturated represented by Saturated, linear or aromatic compounds, preferably in which n and m are each 1 are used. Examples of the linear iodine-containing bromine compound include 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, and 1-bromo-4.
-Iodoperfluorobutane, 2-bromo-3-perfluorobutane, 3,4-dibromo-1-iodo-1,1,2,2,
4,4-hexafluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1 and the like are used. As the aromatic iodine-containing bromine compound, for example, Monoiodomonobromo-substituted, diiodomonobromo-substituted, monoiododibromo-substituted, (2-iodoethyl)-and (2-bromoethyl) -substituted benzenes at various substitution positions of benzene are used. These iodine-containing bromine compounds generally provide fluorine-containing elastomers which are bonded to molecular terminals to achieve efficient crosslinking, and are therefore used in amounts of about 0.01 to 5% by weight, preferably about 0.05 to 3% by weight, as iodine and bromine, respectively. %.

The fluorine-containing elastomer in which these iodine-containing and bromine compounds are bonded in a molecule is crosslinked by an organic peroxide. Organic peroxides include benzoyl peroxide, lauroyl peroxide, ditertiary butyl peroxide, dicumyl peroxide, ditertiary butylcumyl peroxide, 1,1-di (tertiary butylperoxy) -3, 3,5-trimethylcyclohexane, 1,1-bis (α, α-dimethylbutylperoxy) cyclohexane, 1,1-bis (α, α-dimethylbutylperoxy)
-3,3,5-trimethylcyclohexane, 2,5-dimethyl-
2,5-bis (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-
3,1,3-bis (tert-butylperoxydiisopropyl) benzene, α, α-bis (tert-butylperoxy-
m-isopropyl) benzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tertiary butylperoxybenzoate, tertiary butylperoxyisopropyl carbonate, n-butyl-4,4-bis ( Tributyl peroxy) valerate, tertiary butyl peroxy-3,3,5
Trimethylhexanoate or the like is generally used in a proportion of about 0.1 to 15 parts by weight, preferably about 0.5 to 5 parts by weight, per 100 parts by weight of the fluorine-containing elastomer.

Examples of the polyfunctional compound include tri (meth) allyl isocyanurate, tri (meth) allyl cyanurate, triallyl trimellitate, N, N'-m-phenylenebismaleimide, diallyl phthalate, tris (diallylamine) -s- Polyfunctional compounds such as triazine, triallyl phosphite, (di) ethylene glycol diacrylate, neopentyl glycol diacrylate, etc., which improve mechanical strength and compression set, are fluorine-containing elastomers
About 0.1 to 20 parts by weight, preferably about 0.5 to 10 parts by weight per 100 parts by weight
Used in parts by weight.

As the powdered activated carbon, generally, coconut, coal, charcoal, wood, petroleum pitch, or the like is used as a raw material, which is calcined and activated, and is characterized by its high adsorptivity. In the present invention, the adsorption capacity and particle size (about 5 to 30
0 mesh, preferably about 150 mesh or less), from the viewpoint of availability and the like, coconut palm, charcoal, and wood-based raw materials are desirable, and various pHs (powdered activated carbon is added to boiling water, followed by stirring, standing and cooling after standing The pH of the aqueous phase can be measured, and the pH can be about 7 to 12, preferably about 9 to 12.
Eleven are preferred because they give the best physical properties. These powdered activated carbons are made of fluoroelastomer 10
It is used at a ratio of about 1 to 30 parts by weight, preferably about 5 to 15 parts by weight, per 0 parts by weight. If the usage rate is lower than this,
The effect of preventing the generation of toxic gas and the permanent compression set of the vulcanizate are not sufficiently satisfied. On the other hand, if the ratio is higher than this, the strength of the normal value is lowered, which is not preferable.

The fluorine-containing elastomer composition according to the present invention contains the above components as essential components, and preferably further contains a sulfur-containing compound used as an additive for rubber.

As the sulfur-containing compounds generally used as rubber additives, for example, the following compounds are used in an amount of about 0.1 to 5 parts by weight, preferably about 0.1 part by weight, per 100 parts by weight of the fluorine-containing elastomer.
It is used in a proportion of 5 to 2 parts by weight.

(1) Thioureas: N, N'-diphenylthiourea, N, N'-diethylthiourea, trimethylthiourea, tributylthiourea, tetramethylthiourea, tetraethylthiourea, 1,3-bis (dimethylaminopropyl) (2) Thiazoles: 2-mercaptobenzothiazole or its sodium salt, zinc salt, cyclohexylamine salt, benzothiazyl disulfide, 2- (4'-morpholinodithio) benzothiazole, etc. (3) Thiuram Classes: tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram monosulfide, pentamethylenethiuram disulfide, etc. (4) Dithiocarbamic acid salts: dimethyldithiocarbamic acid, diethyldithiocarbamic acid Acid, dibutyldithiocarbamic acid, N-ethyl-N
Zinc salts such as phenyldithiocarbamic acid, dibenzyldithiocarbamic acid, N-pentamethylenedithiocarbamic acid, sodium salts, copper salts, iron salts, tellurium salts, nickel salts, piperidine salts, etc. (5) Xanthates: zinc butylxanthogenate (6) Benzimidazoles: 2-mercaptobenzimidazole or its zinc salt, benzyldiazabicycloammonium salt, benzyltriphenylphosphonium salt, etc., 2-mercaptomethylbenzimidazole, etc. (7) Oxazolines: 2-mercaptobenzoxazoline or its zinc salt, etc. (8) Sulfenamides: N-cyclohexyl-2-benzothiazolylsulfenamide, etc. The composition is prepared by adding carbon Other additives such as fillers such as rubber, reinforcing agents, plasticizers, lubricants, processing aids, pigments, etc. are added as necessary, and are commonly used in roll mixing, kneader mixing, Banbury mixing, solution mixing, etc. It is performed by mixing by any mixing method.

As carbon black, MT carbon black is generally used, and in addition, FT carbon black, SRF carbon black, FEF carbon black, SAF carbon black and the like are also used. These carbon blacks are used in an amount of about 50 parts by weight or less, preferably about 5 to 30 parts by weight, per 100 parts by weight of the fluoroelastomer, and improve the strength, compression set and the like.

Crosslinking of the composition is generally performed by primary crosslinking performed at about 100 to 250 ° C. for about 1 to 120 minutes and secondary crosslinking performed at about 150 to 250 ° C. for about 0 to 30 hours.

〔The invention's effect〕

The peroxide-curable fluoroelastomer composition according to the present invention is prepared by adding activated carbon, which is rarely used as a compounding agent for rubber, to obtain an organic peroxide of a fluoroelastomer containing iodine and bromine in the molecule. Not only can the generation of toxic gases such as methyl iodide and methyl bromide during the thermal crosslinking by the oxides be avoided, but also the reduction of the compression set of the vulcanizate can be effectively prevented.

〔Example〕

 Next, the present invention will be described with reference to examples.

Reference Example In a 3 liter autoclave, 1500 ml of deionized water and 7.5 g of ammonium perfluorooctanoate were charged, and the internal space was a mixed gas of vinylidene fluoride / hexafluoropropene / tetrafluoroethylene (molar ratio: 42/38/20). Was replaced sufficiently. Then, the internal pressure was increased to 12 with this mixed gas.
After pressurization to kg / cm ² G, 4.0 g of 1-bromo-2-iodoperfluoroethane was injected, and the internal temperature was raised to 80 ° C. with stirring. At this time, the internal pressure becomes 16 kg / cm ² G.

Thereto, 0.5 g of ammonium persulfate dissolved in 20 ml of deionized water was added to start a polymerization reaction. Since the pressure decreases with the progress of the reaction, when the internal pressure is reduced to 15 kg / cm ² G, the internal pressure decreases to 16% with a mixed gas of vinylidene fluoride / hexafluoropropene / tetrafluoroethylene (molar ratio 58/20/22).
re pressurized to kg / cm ² G, the polymerization was continued at a pressure of 15~16kg / cm ² G in the same manner, the reaction was stopped by purging unreacted gas mixture in the 24 hours after autoclave.

A 5% aqueous potassium alum solution was added to the obtained aqueous emulsion to coagulate the resulting polymer, followed by washing with water and drying.
468 g of a rubbery copolymer having a three-component copolymer molar ratio of 58/25/17 and [η] = 0.68 (in acetone, at 35 ° C.) was obtained.

Examples 1 to 5 100 parts by weight of the iodine and bromine-containing fluoroelastomer obtained in the above reference example, 15 parts by weight of MT carbon black, 10 parts by weight of triallyl isocyanurate (concentration: 60%), 2,5-dimethyl-2 , 5-di (tert-butylperoxy)
Hexane (concentration: 40%) 3.75 parts by weight, lead oxide 3 parts by weight, sulfur-containing compound (2-mercaptobenzimidazole 8
1 part by weight of benzyl-1,8-diazabicyclo [5,4,0] undecene salt) and 5 parts by weight of powdered activated carbon (having a particle size of 150 mesh or less) of various pHs are roll-mixed, and the prepared fluoroelastomer composition is prepared. The material was vulcanized into a sheet and a P-24 O-ring by primary vulcanization at 180 ° C for 10 minutes and secondary vulcanization at 200 ° C for 22 hours.

For this sheet, the vulcanization properties were measured according to JIS K-6301, and for the O-ring, 200 ° C, 70 hours, 2 hours
The compression set was measured under the condition of 5% compression.

(Powdered activated carbon) Example 1: pH 5.0 Example 2: pH 6.3 Example 3: pH 7.4 Example 4: pH 10.2 Example 5: pH 9.9 Comparative Example 1 In Examples 1 to 5, The amount of MT carbon black was changed to 20 parts by weight, and powdered activated carbon was not used.

Examples 6-10 In Examples 1-5, instead of 3.75 parts by weight of 2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane (40% concentration), 1,1-bis ( 1.5 parts by weight of (α, α-dimethylbutylperoxy) cyclohexane was used, and the primary vulcanization was changed to 150 ° C. for 10 minutes.

Comparative Example 2 In Examples 6 to 10, the amount of MT carbon black was changed to 20 parts by weight, and powdered activated carbon was not used.

Examples 11 and 12 In Examples 4 and 5, no sulfur-containing compound was used.

Comparative Example 3 In Examples 11 and 12, the amount of MT carbon black was changed to 20 parts by weight, and powdered activated carbon was not used.

Examples 13 to 14 In Examples 4 and 5, the amount of MT carbon black and the amount of powdered activated carbon were changed to 10 parts by weight, respectively, and no sulfur-containing compound was used.

Examples 15 to 16 In Examples 4 and 5, the amount of powdered activated carbon was changed to 20 parts by weight, and no MT carbon black and no sulfur-containing compound were used.

Example 17 In Example 4, the amount of the activated carbon powder was changed to 20 parts by weight, and no MT carbon black was used.

The measurement results in the above Examples and Comparative Examples are shown in the following table.

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Claims (2)

(57) [Claims] 1. A peroxide-curable fluorine-containing elastomer composition comprising a fluorine-containing elastomer containing iodine and bromine in the molecule, an organic peroxide, a polyfunctional compound and powdered activated carbon. 2. A powder containing a fluorine-containing elastomer containing iodine and bromine in the molecule, an organic peroxide, a polyfunctional compound, a sulfur-containing compound used as an additive for rubber, and powdered activated carbon. An oxide-vulcanizable fluorine-containing elastomer composition.