JPH0616714A - Method for treating fluorine-containing elastomer latex - Google Patents

Abstract

PURPOSE:To treat a latex which is a fluorine-containing elastomer latex, prepared by an emulsion polymerization, containing iodine and/or bromine in the molecule and capable of improving the engine oil resistance of a cross-linked fluorine-containing elastomer thereof. CONSTITUTION:A halide of carboxylate of Li, Ca, Mn, Co, Ni or Zn is used as a salting out agent in salting out a fluorine-containing elastomer latex prepared by carrying out the emulsion polymerization in the presence of an fan iodine and bromine-containing compound, an iodine- or a bromine-containing compound. When a salting out agent other than that described above is used, the coagulated produced polymer is immersed in an aqueous solution of the specific compound.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for treating a fluorine-containing elastomer latex. More specifically, it relates to a method for treating a fluorine-containing elastomer latex containing iodine and / or bromine in the molecule.

[0002]

Fluorine-containing elastomers containing iodine and / or bromine in the molecule can be crosslinked with an organic peroxide, and the crosslinked product is excellent in heat resistance and chemical resistance. However, applications such as contact with engine oil, such as oil seals, packings, gaskets, O
If it is used as a ring, it cannot avoid deterioration.

That is, many engine oils contain amine-based corrosion inhibitors, antiwear agents, antioxidants, etc., and cracks are observed on the surface of the test piece during the immersion test in engine oil. Occurrence or cracking during tensile elongation is unavoidable.

[0004]

The object of the present invention is to treat a fluorine-containing elastomer latex containing iodine and / or bromine in the molecule, which can improve the engine resistance of the fluorine-containing elastomer crosslinked product. To provide a method.

[0005]

The object of the present invention is as follows.
Iodine-containing bromine compounds, fluorine-containing elastomer latex obtained by emulsion polymerization in the presence of iodine-containing compounds or bromine-containing compounds, salting out halides or carboxylates of Li, Ca, Mn, Co, Ni or Zn It is achieved by salting out as an agent.

When salting out a fluorine-containing elastomer latex containing iodine and bromine in the molecule, it is not possible to use a salting-out agent which has been generally used in the past, such as 5% potassium alum aqueous solution or 10% sodium chloride. It is described, for example, in Japanese Patent Publication No. 1-57125, which describes an invention by a person.

In the present invention, the above-mentioned specific salting-out agent is used in place of such salting-out agent. Such a salting-out agent is generally used as an aqueous solution having a concentration of about 0.5% or more, preferably about 1 to 10%. Instead of these aqueous solutions,
When a sodium chloride aqueous solution is used as in the conventional example, only the engine oil resistance is inferior.
However, when salting out using a salting-out agent other than the specific salting-out agent such as an aqueous solution of sodium chloride, the coagulated polymer is washed with water and then immersed in an aqueous solution of the specific compound.
By (including spraying), the same effect can be obtained. These salting out or dipping is performed at about 20 to 90 ° C,
It is preferably carried out at about 50 to 90 ° C.

The fluorine-containing olefin constituting the main part of the fluorine-containing elastomer containing iodine and / or bromine in the molecule used in the present invention has 2 carbon atoms.
~ 8 are preferably used, such as vinylidene fluoride, tetrafluoroethylene, hexafluoropropene, pentafluoropropene, chlorotrifluoroethylene, methyl perfluoro vinyl ether, ethyl perfluoro vinyl ether, n- or iso-propyl perfluoro. Vinyl ether, n-, iso- or 3-butyl perfluoro vinyl ether, n- or iso-amyl perfluoro vinyl ether, perfluoro (methyl vinyl ether), perfluoro (ethyl vinyl ether),
Perfluoro (n- or iso-propyl vinyl ether), perfluoro (n-, iso- or tertiary butyl vinyl ether), perfluoro (n- or iso-amyl vinyl ether), perfluoro (propoxypropyl vinyl ether), etc. One of them is mainly used, and in addition to these, vinyl fluoride, trifluoroethylene, perfluorocyclobutene, perfluoro (methylcyclopropene), hexafluoroisobutene, 1,2,2-trifluorostyrene, perfluorostyrene, etc. Is 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 unsaturated vinyl esters such as ethylene, propylene, butene and vinyl acetate, and alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether having 2 to 6 carbon atoms.
Of these, and these are generally copolymerized in a proportion of about 0.1 to 50 mol%.

Further, examples of the fluorine-containing diene include 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 perfluoro vinyl vinyl ether. These fluorinated dienes are preferably copolymerized so that they are present in the fluorinated elastomer in a proportion of about 1 mol% or less. When copolymerized at a ratio higher than this, gelation of the copolymer elastomer becomes remarkable, and processability (flow characteristics) and elongation of the vulcanized product deteriorate.

Specific fluorine-containing olefin copolymers include hexafluoropropene-vinylidene fluoride copolymer, hexafluoropropene-vinylidene fluoride-tetrafluoroethylene terpolymer, and tetrafluoroethylene-vinylidene fluoride. -Perfluoro (methyl vinyl ether) terpolymer, tetrafluoroethylene-vinylidene fluoride-perfluoro (propyl vinyl ether) terpolymer, tetrafluoroethylene-perfluoro (propoxypropyl vinyl ether) copolymer, tetrafluoro Ethylene-perfluoro (methyl vinyl ether) copolymer, tetrafluoroethylene-propylene copolymer, tetrafluoroethylene-vinylidene fluoride-hexafluoropropene-pentafluoropropene quaternary copolymer, tetrafluoroethylene-hexaf Luoro propene-
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 3
Terpolymer, vinylidene fluoride-methyl perfluorovinyl ether-perfluoro (methyl vinyl ether) terpolymer, tetrafluoroethylene-methyl perfluorovinyl ether-perfluoro (methyl vinyl ether) terpolymer, vinylidene fluoride -Hexafluoropropene-tetrafluoroethylene-methyl perfluorovinyl ether quaternary copolymer, tetrafluoroethylene-n-
Butyl perfluoro vinyl 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 terpolymer, etc. To be

The polymerization reaction is carried out by emulsion-polymerizing the fluorinated olefin or the olefin-containing olefin with the above comonomer by a conventionally known method. Emulsion polymerization is carried out, for example, with inorganic peroxides such as persulfate, hydrogen peroxide, perchlorate, and the like.
Water-soluble polymerization initiators such as organic peroxides such as butyl hydroperoxide and disuccinyl peroxide are used, and these polymerization initiators include sulfites, hyposulfites, ascorbic acid, ferrous salts, hydroxymethanesulfine. It is also used as a redox system in combination with a reducing agent such as sodium acidate. Further, the molecular weight of the fluorine-containing elastomer can be adjusted by using a chain transfer agent such as methanol, ethanol, isopentane, ethyl acetate, diethyl malonate and carbon tetrachloride. Further, an emulsifier such as a fluorinated carboxylic acid salt or a fluorinated sulfonic acid salt may be used for the purpose of stably dispersing the polymer particles in the polymerization liquid, increasing the polymer concentration, and preventing the adhesion of the polymer to the polymerization tank.

These various polymerization reactions are carried out at a temperature within the range where the radical reaction proceeds and depolymerization of the produced polymer does not occur, generally at a temperature of about -30 to 150 ° C. However, in the case of a redox system, the reaction is carried out at a temperature of about 0 to 50 ° C, and if the reaction is carried out in such a low temperature range, the iodine-containing bromine compound, the iodine-containing compound or the bromine-containing compound is thermally decomposed. It can be suppressed and the crosslinking density of the vulcanized product can be increased. The polymerization pressure is also not particularly limited, and a wide pressure range can be adopted depending on the intended polymerization rate and degree of polymerization, but it is generally carried out within the range of about 1 to 100 kgf / cm ² .

During this polymerization reaction, an iodine-containing bromine compound,
When an iodine-containing compound or a bromine-containing compound is made to coexist, iodine and / or bromine are introduced into the fluorine-containing olefin copolymer to form a crosslinking point at the time of organic peroxide crosslinking.

The iodine-containing bromine compound has the general formula RBrn
Im (R: fluorohydrocarbon group, chlorofluorohydrocarbon group, chlorohydrocarbon group or hydrocarbon group, n, m: 1 or
A saturated or unsaturated, chain-like or aromatic compound represented by 2), wherein n and m are each 1 is used. Examples of the chain iodine-containing bromine compound include 1-bromo-2-iodoperfluoroethane, 1-
Bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3,4-dibromo-1-iodo-1,1,2,2,4 1,4-hexafluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, etc. are used, and examples of the aromatic iodine-containing bromine compound include benzene. The monoiodomonobromo substitution product, diiodomonobromo substitution product, monoiododibromo substitution product, (2-iodoethyl) and (2-bromoethyl) substitution product at various substitution positions of are used. These iodine-containing bromine compounds generally give fluorine-containing elastomers that are bound to the molecular ends to achieve efficient cross-linking, and therefore iodine and bromine are added in amounts of about 0.01 to 5% by weight, preferably about 0.05 to 3% by weight, respectively. Combine so that it becomes%.

As the iodine-containing compound, an aromatic compound or perfluoroaromatic compound which is poly-substituted by an iodine atom or an alkyl iodide group represented by an ethyl iodide group is used. % By weight, preferably about 0.05 to 3% by weight, or a saturated or unsaturated aliphatic hydrocarbon, fluoroaliphatic hydrocarbon or chlorofluoroaliphatic iodo-substituted product, It is used in the fluorine-containing elastomer in a proportion such that the binding amount of iodine is about 0.01 to 10% by weight.

As the bromine-containing compound, an aromatic compound or perfluoroaromatic compound which is poly-substituted by a bromine atom or an alkyl bromide group represented by an ethyl bromide group is used.
5 wt%, preferably about 0.05 to 3 wt% in such a proportion that the bromine substitution product of the saturated aliphatic hydrocarbon is about 0.01 to 10 wt% as bromine in the fluorine-containing elastomer.
%, And the bromine-containing olefin is about 0.05% by weight as bromine in the fluoroelastomer.
As described above, they are generally used in such a proportion that the binding amount is about 0.3 to 1.5% by weight, and 3- or 2-bromoperfluoropropyl perfluorovinyl ether and the like can also be used.

The fluorine-containing elastomer having these iodine-containing and / or bromine compounds bonded in the molecule is cross-linked with an organic peroxide. As the organic peroxide,
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 (tertiary 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, 3rd
Butyl peroxybenzoate, tertiary butyl peroxy isopropyl carbonate, n-butyl-4,4-bis (tertiary butyl peroxy) valerate, tertiary butyl peroxy-3,
3,5-Trimethylhexanoate and the like are generally used in a ratio of about 0.1 to 15 parts by weight, preferably about 0.5 to 5 parts by weight, based on 100 parts by weight of the fluoroelastomer.

Upon crosslinking, a polyfunctional compound is used in combination. Such polyfunctional compounds include tri (meth) allyl isocyanurate, tri (meth) allyl cyanurate,
Machines such as triallyl trimellitate, N, N'-m-phenylene bismaleimide, diallyl phthalate, tris (diallylamine) -s-triazine, triallyl phosphite, (di) ethylene glycol diacrylate, neopentyl glycol diacrylate The polyfunctional compound for improving the mechanical strength, compression set, etc. is used in an amount of about 0.1 to 20 parts by weight, preferably about 0.5 to 10 parts by weight, based on 100 parts by weight of the fluoroelastomer.

The crosslinking of the composition is generally about 100-250 ° C.
Primary cross-linking for about 1 to 120 minutes and at about 150 to 250 ℃
The secondary cross-linking is performed for about 0 to 30 hours.

[0021]

EFFECTS OF THE INVENTION When salting out a fluorine-containing elastomer latex obtained by emulsion polymerization in the presence of an iodine-containing bromine compound, an iodine-containing compound or a bromine-containing compound, Li, C
By using a halide or carboxylate of a, Mn, Co, Ni or Zn as a salting-out agent, a fluorine-containing elastomer excellent in engine oil resistance can be obtained.

When a salting-out agent other than the above is used,
The same effect can be obtained by immersing the coagulated product polymer in an aqueous solution of the specific compound.

[0023]

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

Example 1 50 parts of deionized water were placed in an autoclave having an internal volume of 10 liters.
00 ml and 6.6 g of ammonium perfluorooctanoate were charged, and the inner space was sufficiently replaced with nitrogen gas. After depressurizing the inside, pressurize the internal pressure to 23 kg / cm ² G with a mixed gas of vinylidene fluoride / hexafluoropropene / tetrafluoroethylene (molar ratio 47/41/12), then 1-bromo-2-iodo. 7.4 g of perfluoroethane was injected, and the internal temperature was raised to 70 ° C with stirring. At this time, the internal pressure is 31 kg / cm ² G.

0.6 g of ammonium persulfate dissolved in 50 ml of deionized water was added thereto to start the polymerization reaction. Since the pressure decreases with the progress of the reaction, the internal pressure is 28 kg / cm ² G
When it has decreased to 29 kg / cm ² G with a mixed gas of vinylidene fluoride / hexafluoropropene / tetrafluoroethylene (molar ratio 61/24/15), it is 28-29 kg /
Polymerization was continued at a pressure of cm ² G, and after 6 hours, the unreacted mixed gas in the autoclave was purged to stop the reaction.

The resulting aqueous emulsion was added to a 5% aqueous solution of cobalt acetate at 70 ° C. to coagulate the produced polymer, which was then washed with water and dried to give a three-component copolymer molar ratio of 66/18. At / 16, [η]
1350 g of a rubber-like copolymer having a = 0.70 (in acetone, 35 ° C.) was obtained.

Examples 2 to 8 In Example 1, instead of 5% cobalt acetate aqueous solution,
The following 5% aqueous solutions of inorganic salts were used.

Comparative Example In Example 1, instead of the 5% cobalt acetate aqueous solution,
A 5% aqueous sodium chloride solution was used.

Example 9 In the comparative example, the coagulated product polymer was washed with water, immersed in a 5% aqueous solution of cobalt acetate, and dried to obtain a rubbery copolymer.

100 parts by weight of the fluorine-containing elastomer containing iodine and bromine obtained in the above Examples and Comparative Examples, M
20 parts by weight of T carbon black, 10 parts by weight of triallyl isocyanurate (concentration 60%) and 2,5-dimethyl-2,5-di (3rd
Butyl peroxy) hexane (concentration 40%) 3.75 parts by weight, lead oxide 3 parts by weight roll-mixed, the fluorine-containing elastomer composition prepared 180 ° C., 10 minutes primary vulcanization and 200 ° C.,
Each sheet was vulcanized and molded by secondary vulcanization for 22 hours.

The following items were measured on these sheets. Vulcanization physical properties: According to JIS K-6301 Engine oil resistance: SUS closed test tubes are used to measure physical property changes after immersion in Castle Company's clean turbo oil at 175 ° C for 70 hours Elongation when cracks occur: Clean turbo 175 in oil
After soaking for 24 hours and 70 hours at ℃, the test piece is pulled by the same method as JIS K-6301 to generate cracks on the surface of the test piece, and the elongation at that time is measured. The measurement results are shown in the following table. . Table Example Comparative example 1 2 3 4 5 6 7 8 9 [Normal physical properties] Hardness (JIS-A) 72 72 72 72 72 72 72 72 72 71 100% Modulus (kg / cm ² ) 43 45 47 46 47 43 47 43 45 45 Tensile strength (kg / cm ² ) 219 203 213 228 245 225 225 201 220 234 Elongation (%) 318 281 302 314 272 318 314 287 301 283 [Engine oil resistance] Hardness change (point) 0 0 0 0 0 0 -1 0 0 +11 00% Modulus change (%) -4 -4 -7 -3 -4 -5 -8 -2 -4 -19 Change in tensile strength (%) -49 -44- 48 -49 -50 -47 -49 -42 -44 -59 Elongation change (%) -35 -33 -36 -37 -38 -36 -37 -28 -30 -40 [Elongation at crack occurrence] 24 hours (% ) 189 180 182 176 178 180 182 180 182 110 70 hours (%) 98 82 90 94 80 80 92 88 90 45

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[Procedure amendment]

[Submission date] February 7, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

The following items were measured on these sheets. Vulcanization physical properties: According to JIS K-6301 Engine oil resistance: SUS closed test tubes are used to measure physical property changes after immersion in Castle Company's clean turbo oil at 175 ° C for 70 hours Elongation when cracks occur: Clean turbo 175 in oil
After soaking for 24 hours and 70 hours at ℃, the test piece is pulled by the same method as JIS K-6301 to generate cracks on the surface of the test piece, and the elongation at that time is measured. The measurement results are shown in the following table. . Table Example Comparative example 1 2 3 4 5 6 7 8 9 [Normal physical properties] Hardness (JIS-A) 72 72 72 72 72 72 72 72 72 71 100% Modulus (kg / cm ² ) 43 45 47 46 47 43 47 43 45 45 Tensile strength (kg / cm ² ) 219 203 213 228 245 225 225 201 220 234 Elongation (%) 318 281 302 314 272 318 314 287 301 283 [Engine oil resistance] Hardness change (point) 0 0 0 0 0 0 -1 0 0 +1 100% Modulus change (%) -4 -4 -7 -3 -4 -5 -8 -2 -4 -19 Tensile strength change (%) -49 -44- 48 -49 -50 -47 -49 -42 -44 -59 Elongation change (%) -35 -33 -36 -37 -38 -36 -37 -28 -30 -40 [Elongation at crack occurrence] 24 hours (% ) 189 180 182 176 178 180 182 180 182 110 70 hours (%) 98 82 90 94 80 80 92 88 90 45

Claims (3)

[Claims] 1. An iodine-containing bromine compound, a fluorine-containing elastomer latex obtained by emulsion polymerization in the presence of an iodine-containing compound or a bromine-containing compound, is a halide or carvone of Li, Ca, Mn, Co, Ni or Zn. A method for treating a fluorine-containing elastomer latex, which comprises salting out an acid salt as a salting-out agent. 2. A fluorine-containing elastomer latex obtained by emulsion-polymerizing an iodine-containing bromine compound, an iodine-containing compound or a bromine-containing compound in the presence of a halide or carvone of Li, Ca, Mn, Co, Ni or Zn. A method for treating a fluorine-containing elastomer latex, which comprises salting out with a salting-out agent other than acid salt and then immersing in an aqueous solution of a halide or carboxylate of Li, Ca, Mn, Co, Ni or Zn. 3. A fluorine-containing elastomer composition containing the fluorine-containing elastomer obtained in claim 1 or 2, an organic peroxide and a polyfunctional compound.