JPS5952645B2 - Method for producing fluorine-containing elastomer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a fluorine-containing elastomer, and more specifically, a method for producing a fluorine-containing elastomer.
The present invention relates to a method for producing a novel fluorine-containing elastomer made of an alkyl vinyl ether copolymer.

It has been known that propylene-tetrafluoroethylene copolymers can be made into excellent fluororubbers.

For example, Japanese Patent Publication No. 43-24199, U.S. Patent No. 3
See specification No. 467,635, British Patent No. 1,284,247, etc. However, the fluorine-containing elastomer made of such a propylene-tetrafluoroethylene copolymer is
Although it had excellent heat resistance, chemical resistance, etc., it had insufficient low temperature properties and moldability. Based on the recognition of the above-mentioned problems, the present inventor has conducted various studies and examinations in order to provide a means for improving the low-temperature properties and moldability of propylene-tetrafluoroethylene copolymers. result,
It has been found that the object can be advantageously achieved by copolymerizing an alkyl vinyl ether such as propyl vinyl ether with tetrafluoroethylene and propylene.

In other words, by copolymerizing alkylbi and nyl ethers in a specific proportion, the low-temperature properties of the propylene-tetrafluoroethylene-based copolymer can be improved without impairing its heat resistance, chemical resistance, etc. In the continuous molding process, the surface condition, cross-sectional shape, mold flowability, etc. of the molded product can be improved, and the extrusion speed can be increased. Thus, the present invention
It was completed based on the above-mentioned discoveries, and was developed using propylene and the four-futsu chemical industry. In producing a fluorine-containing elastomer by copolymerizing tyrene by the action of a polymerization initiator,
Alkyl vinyl ether and other comonomers are further copolymerized as desired to produce 52 to 80 mol% of tetrafluoroethylene.
, obtaining a propylene-tetrafluoroethylene-alkyl vinyl ether copolymer containing as constituent units 10 to 30 mol% of propylene, 10 to 38 mol% of alkyl vinyl ether, and 0 to 10 mol% of other comonomers. The present invention provides a new method for producing a fluorine-containing elastomer.

The novel propylene-tetrafluoroethylene-alkyl vinyl ether copolymer of the present invention has a glass transition temperature of 0°C compared to the conventional propylene-tetrafluoroethylene copolymer.
However, as is clear from the fact that it has a glass transition temperature of about 5 to -15°C, it has significantly superior low-temperature properties.

Furthermore, in terms of heat resistance, chemical resistance, etc., it is not inferior to conventional propylene-tetrafluoroethylene copolymers. Moreover, since the molding processability is improved, it is possible to continuously mold products with complex shapes or irregular shapes. That is, by appropriate blending and vulcanization, it is possible to produce a fluorine-containing elastomer that has excellent heat resistance, chemical resistance, etc. and can be used over a wide range of temperatures from low to high temperatures. Therefore, the fluorine-containing rubber can be advantageously applied to packing materials, O-rings, diaphragms, gaskets, hoses, rolls, etc. that require such performance. According to the present invention, tetrafluoroethylene 52-80 mol%, propylene 10-30 mol%, alkyl vinyl ether 10-38 mol%
A new vulcanizable fluorine-containing elastomer containing 0 to 10 mol% of other comonomers is obtained.

In the present invention, 55 to 65 mol% of tetrafluoroethylene
Particularly good results are obtained when the fluorine-containing elastomer is made of 20 to 30 mol % of propylene and 10 to 25 mol % of alkyl vinyl ether. If the content of alkyl vinyl ether is too small, the effect of improving low temperature properties and moldability will be insufficient, and if the content is too large, heat aging resistance will be impaired.
Undesirable. Regarding the content of tetrafluoroethylene and propylene, it is desirable to select the above range from the viewpoint of heat resistance, chemical resistance, properties as an elastomer, ease of synthesis, etc. In the present invention, as the alkyl vinyl ether, conventionally known or well-known ones can be exemplified without particular limitation, but usually, the general formula, CH2=CH-0-R (However, R in the formula has 1 carbon
It is an alkyl vinyl ether represented by ~6 alkyl groups).

Specific examples include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, isopropyl vinyl ether, isobutyl vinyl ether, hexyl vinyl ether, and the like. In the general formula, R preferably has 1 to 5 carbon atoms, and may be linear or branched. The copolymerization reaction in the present invention can be carried out using various polymerization methods such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization, or appropriate methods such as catalytic polymerization using a polymerization initiator, ionizing radiation polymerization, redox polymerization, etc. It can be implemented by means.

In addition to the main components of ethylene tetrafluoride, propylene, and alkyl vinyl ether, components copolymerizable with these, such as vinyl fluoride, vinylidene fluoride, propylene hexafluoride, fluorovinyl ether, and chlorotrifluoroethylene, may also be suitably used. may be copolymerized. For example, 10
Copolymerization can be carried out in a small amount of about mol% or less. As such comonomers, monomers that form a curing site can also be employed, and examples thereof include acrylic acid and its alkyl esters, methacrylic acid and its alkyl esters, chloroethyl vinyl ether, diethylene glycol divinyl ether, glycidyl vinyl ether, etc. may be copolymerized in a small amount of about 5 mol% or less. Therefore, the molecular weight of the fluorine-containing elastomer is usually desirably about 20,000 or more in view of vulcanized physical properties such as tensile strength, and in order to simultaneously satisfy both moldability and physical properties after vulcanization. It shouldn't be too high either. For example 2 to 15
It is desirable to use a fluorine-containing elastomer having a molecular weight of about 10,000, especially about 30,000 to 100,000. The method of the present invention can be carried out using various polymerization methods or under various polymerization conditions as described above.

For example, in organic solvents such as fluorinated or fluorinated chlorinated saturated hydrocarbons such as trichloromonofluoromethane, trichlorotrifluoroethane, and perfluorocitabutane, so-called chlorofluorocarbon solvents, and alcohol solvents such as tertiary butanol. In this case, −40
A relatively low reaction pressure, for example a pressure of about 1 to 50 kg/Cm2, can be employed at a temperature of about 150 DEG C. to +150 DEG C.
Further, suspension polymerization or emulsion polymerization may be carried out using an aqueous medium, and in emulsion polymerization, polyfluorinated or polyfluorinated chlorinated alkyl-based dispersants can be preferably employed. In such suspension polymerization and emulsion polymerization, chlorinated hydrocarbons, liquid hydrocarbons, dispersion stabilizers such as trichlorotrifluoroethane, tertiary butanol, reaction accelerators, and the like can be used as appropriate. Furthermore, it is possible to employ polymerization initiators such as peroxides, azo compounds, and persulfates, and the copolymerization reaction may also be carried out by irradiation with ionizing radiation such as gamma rays from cobalt-60. . In the case of polymerization in an aqueous medium, it can be carried out, for example, at a temperature of about 50 to 100° C. and a pressure of about 5 to 200 kg/CITl. In addition, redox initiators can be used to reduce the temperature to -20°C.
It is also possible to use a low temperature of about +50°C. The method of the present invention can be carried out in a batch, semi-continuous, or continuous manner as appropriate, and various polymerization conditions, polymerization operations, and polymerization methods may be used depending on the purpose or the polymerization method employed. It is desirable to select equipment, etc. In the manner described above, a transparent to white fluorine-containing elastomer with rubber-like elasticity is obtained, which has superior low-temperature properties and moldability than conventional propylene-tetrafluoroethylene copolymer elastomers. It is possible to manufacture The fluorine-containing elastomer thus obtained can be chemically crosslinked by various crosslinking means to form a rubber-like crosslinked product. For example, if the monomer that will become the curing site is not copolymerized, it can be crosslinked using an organic peroxide, or it can be crosslinked by radiation by irradiation with ionizing radiation such as gamma rays or electron beams. is also possible. Furthermore, when copolymerizing monomers that serve as curing sites, commonly used vulcanizing agents such as metal oxides, polyvalent amines, or nucleophilic reagents such as hydroquinone and bisphenol A are combined with an appropriate vulcanization accelerator. They can also be used in combination. In this case,
Various crosslinking aids, fillers, reinforcing agents, etc. can be added and mixed, and various vulcanization formulations can be adopted. The fluorine-containing elastomer obtained by the method of the present invention can also be crosslinked by irradiation with ionizing radiation such as α rays, β rays, γ rays, neutron beams, accelerated particle beams, X-rays, and electron beams.

Usually, gamma rays from cobalt-60, accelerated particle beams, electron beams, etc. are preferred. For example, at a dose rate of about 102 to 109 Roentgen/hour, especially about 103 to 5 x 107 Roentgen/hour, the irradiation dose is about 104 to 108 rats, especially about 10
It can be converted into a crosslinked copolymer by irradiating it with ionizing radiation to a range of about 6 to 5 x 107 rats. Therefore, ionizing radiation can be irradiated in air, and the irradiation atmosphere must be kept in a vacuum or under an air flow such as argon, helium, nitrogen, etc.
It can even be kept underwater. The crosslinking reaction caused by ionizing radiation irradiation proceeds efficiently at or around room temperature, so the irradiation temperature does not need to be particularly limited, and irradiation temperatures below room temperature, around 100°C, or higher can be adopted. It is. Note that crosslinking by irradiation with ionizing radiation has the advantage that it can be applied to materials that have been previously formed into arbitrary shapes such as films, sheets, pipes, rods, rings, coatings, and the like. Further, the fluorine-containing elastomer obtained by the method of the present invention can be crosslinked by heating using a chemical crosslinking agent such as a peroxy compound.

For example, kyumene hydroperoxide, diisopropylbenzene hydroperoxide, di(tertiary butyl) peroxide, tertiary butyl peroxyacetate,
Organic monoperoxy compounds such as tertiary butylperoxybenzoate and 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexyne-3,2,5-dimethyl-2,5-di(tert-butylperoxy) tertiary butylperoxy)-hexane,
α,α-bis(tert-butylperoxy)-para-diisopropylbenzene, 2,5-dimethyl-2,5-di(
Organic diperoxy compounds such as benzoylperoxy)-hexane are preferred. Thus, the temperature giving a half-life of 5 minutes is 100-200°C, preferably 130-19°C.
Peroxy compounds whose temperature is around 0° C. can be employed particularly advantageously as chemical crosslinking agents. The amount of the chemical crosslinking agent used is not particularly limited and can be selected as appropriate, but it is usually about 0.1 to 20 parts by weight, preferably about 1 to 10 parts by weight, based on 100 parts by weight of the fluorine-containing elastomer. be. When crosslinking such a fluorine-containing elastomer, either by ionizing radiation irradiation or by a chemical crosslinking agent,
Conventionally known or well-known crosslinking aids may be used in combination.

For example, crosslinking aids such as allyl compounds, sulfur, organic amines, maleimides, methacrylates, and divinyl compounds may be employed. Preferably diallyl phthalate,
Organic allyl compounds such as triallyl phosphoric acid, triallyl cyanurate, triallyl isocyanurate, diallylmelamine, and parabenzoquinone dioxime, P, P-
Oxime compounds such as dibenzoylbenzoquinone dioxime are used, and organic allyl compounds are particularly preferred. The amount of the crosslinking aid added is 100% of the fluorine-containing elastomer.
0.1 to 20 parts by weight, preferably 0.1 to 20 parts by weight.
About 2 to 10 parts by weight may be employed. Furthermore, various additives commonly used in conventional crosslinking methods may also be added during crosslinking of the fluorine-containing elastomer.

These additives include metal oxides such as magnesium oxide and lead oxide, reinforcing agents such as carbon black and fine silica, other fillers, pigments, antioxidants, stabilizers, and the like. When adding the various additives described above to the fluorine-containing elastomer, it is desirable to mix the chemical crosslinking agent, crosslinking aid, and other additives sufficiently and uniformly with the raw material fluorine-containing elastomer.

Such mixing may be carried out using conventional rubber kneading rolls, Banbury mixers, or the like. Working conditions during mixing are not particularly limited, but usually 30
By kneading at a temperature of about 80 DEG C. for about 10 to 60 minutes, the additive compound can be sufficiently dispersed and mixed into the fluorine-containing elastomer. It is desirable to select the optimum working conditions and operations during mixing depending on the type and purpose of the raw materials and compounding agents used.Heat crosslinking using a chemical crosslinking agent is a conventionally commonly used operation. can be adopted.

For example, an operation of heating while pressurizing in a mold may be employed, or an operation of heating in a heating furnace after molding by extrusion or injection molding may be employed. Since this copolymer contains alkyl vinyl ether in its constituent units,
Compared to conventional tetrafluoroethylene-propylene two-component copolymers, its moldability is better,
It can be particularly advantageously molded into molded products with complex shapes or by extrusion or injection molding methods. For example, regarding the viscosity of the polymer, which is generally used as an indicator of molding processability, this copolymer is approximately 1/2 that of a copolymer consisting of only two components, tetrafluoroethylene and propylene, at the same molecular weight. 3-1
It has been found to have values of viscosity as low as /2. It is desirable to select optimal conditions for the working conditions during thermal crosslinking depending on the raw materials and formulation used. The temperature during thermal crosslinking may be generally about 80 to 250°C, preferably about 150 to 200°C. Further, the heating time is not particularly limited, but is selected in the range of 5 minutes to 2 hours, preferably in the range of 10 minutes to 2 hours, depending on the chemical crosslinking agent. The heating time can be shortened by increasing the heating temperature. Note that reheating treatment of the resulting crosslinked copolymer can also be employed, and is useful for improving physical properties. For example, reheating treatment at a temperature of 150 to 250°C, preferably 180 to 230°C for about 15 to 25 hours may be employed.
Furthermore, vulcanization at room temperature is also possible for those copolymerized with glycidyl vinyl ether as a curing site unit. The crosslinked fluorine-containing elastomer obtained by the present invention has excellent heat resistance, chemical resistance, and low temperature properties, so it can be used in various applications that require rubber elasticity under a wide range of usage conditions. can be used to advantage.

For example, O-rings for aircraft, ships, and automobiles, gaskets, valve stem seals, diaphragms, sealing materials for dry cleaning equipment, pipes, flexible joints, hoses for the chemical industry, rolls, packing, sealing materials, diaphragms, coating materials, It is useful as a material for parts such as gloves that come into contact with high-temperature, high-concentration acids, alkalis, oils, and solvents. In addition, it can be formed into pipe-shaped, rod-shaped products, etc., and it can also be formed by primary processing into film-shaped or tape-shaped products, and then further shaped by secondary processing such as lamination, pasting, and winding. Of course, processing is also possible. Next, embodiments of the present invention will be described in more detail, but this description does not limit the scope of the present invention in any way.
Of course, it is not fixed. Example 1 and comparative example
1 580 g of deoxygenated water, 2.9 g of ammonium perfluorooctanoate, 1.5 g of ammonium persulfate, and 0.4 g of sodium acid sulfite were placed in a 11 autoclave, and 0.15 g of sodium hydroxide was added to adjust the pH of the aqueous phase.
Adjust to 10.

After replacing the inside of the autoclave with N2, 1.6 g of methyl vinyl ether (hereinafter referred to as MVE) (a). 028 mol), propylene (hereinafter referred to as P), 2.4 g (0.057 mol), and tetrafluoroethylene (hereinafter referred to as 4F) 61 g (4). 61 mol) was charged by automatic pressure. Next, stirring was started at 300 rpm, and the temperature inside the reactor was raised to 70°C.

Once the reaction starts and the pressure starts to drop, the pressure will drop to 30kg/Cm.
・J4F/P/MVE is 55/2 to maintain a constant pressure of
Charge monomer mixed gas with a molar ratio of 5/20 to 4
Continue the time reaction. After the reaction was completed, the monomer was purged and the latex was extracted and coagulated with a 1% CaCl2 aqueous solution, washed and dried to obtain 81.2 g of polymer.
The obtained polymer is a copolymer having a molar ratio of 4F/P/MVE of approximately 52/27/21, and its number average molecular weight at 30°C in THF is 4.
It was 30,000 yen. Further, this copolymer was an elastomer having a glass transition temperature of -7 DEG C., and the viscosity of raw rubber was 31 at 100 DEG C., and the Shore A hardness was 35.

3 parts of organic diperoxide per 100 parts of the above copolymer
parts, triallyl isocyanurate 3 parts, MT carbon 2 parts
5 parts of lead oxide and 10 parts of lead oxide were blended in a roll, and then heated at 160°C.
Press vulcanization was carried out at 00 kg/Cnl2 for 20 minutes, then taken out from the mold, and vulcanization was carried out in an oven at 200° C. for 22 hours.

The tensile strength of the obtained vulcanizate was 51 kg/Cm2, the elongation at break was 510%, and the 100% modulus was 22 kg/CIn.
Z, Shore-A hardness was 63. On the other hand, 4F
/P two-component polymer with a composition molar ratio of 55/45
However, the glass transition temperature is 0° C., and the molecular weight viscosity and Shore A hardness of raw rubber with a molecular weight of 47,000 are 70 and 48, respectively. Example 2 and Comparative Example 2 In a 21 autoclave with a stirrer, 970 g of deoxygenated water, 87 g of tertiary butanol, 29 g of secondary butanol, 5.8 g of ammonium perfluorooctanoate, 2.9 g of ammonium persulfate, and 0 sodium thiosulfate were added. .8g, 0.6g of ferrous sulfate, and 0.3g of sodium hydroxide.
g to adjust the pH of the aqueous phase to 9.5.

After replacing the inside of the autoclave with N2, 1.8 g of glycidyl vinyl ether (hereinafter referred to as GVE) and 1 ethyl vinyl ether (
3.8 g (hereinafter referred to as EVE), 5.3 g of propylene, and 162 g of tetrafluoroethylene were press-fitted. Next, stirring is started at 300 rpm, and the temperature inside the autoclave is raised to 35°C. Once the reaction starts and the pressure starts to drop, the pressure will drop to 25kg/C.
A monomer mixed gas having a molar ratio of 4F/P/EVE/GVE of 55/29/15/1 was charged to maintain a constant pressure of ff, and the reaction was continued for 6 hours. After the reaction was completed, the monomer was purged and the latex was extracted and diluted with 1% CaCl. After coagulating with an aqueous solution, the polymer was washed and dried to obtain 164 g of polymer.
The obtained polymer was a copolymer having a composition with a molar ratio of 4F/P/EVE/GVE of approximately 53/30/16/1, and its number average molecular weight was 80,000. For 100 parts of the above copolymer, 1 part of hydroquinone, 1 part of tris(dimethylaminomethyl)phenol, 3 parts of MT carbon
5 parts were blended using a roll, and then press and oven vulcanization were performed under the same conditions as in Example 1.

Table 1 shows the test results for the main mechanical properties of the obtained vulcanizate. For comparison, an elastomer with a 4F/P/GVE molar ratio of 54/45/1 and a number average molecular weight of 78,000 was synthesized and vulcanized in the same manner. The mechanical properties of the vulcanizate are also shown in Table 1.

Example 3 In Example 2, the two amounts of monomer charged at the start of the reaction were
1.8 g of glycidyl biyl ether, 8.8 g of ethyl biyl ether, 2.3 g of propylene, 1 ethylene tetrafluoride
60g, and the composition of the charge monomer during the reaction is:
Polymerization was carried out in the same manner except that 4F/P/EVE/GVE was 54/15/30/1, and the reaction time was 1 in 4 hours.
31 g of polymer was obtained.

This polymer had a composition of 4F/P/EVE/GVE in a molar ratio of about 51/16/32/1, and a number average molecular weight of 72,000.

Also, the Mooney viscosity (MLl+4) of raw rubber is 34
It had an extremely low glass transition temperature of -12°C, and had excellent low-temperature properties. Further, the vulcanized product that was vulcanized in the same manner as in Example 2 had a tensile strength of 141k.
It exhibited vulcanized physical properties of g/CIIl2, elongation of 190%, and 100 modulus of 42.

Example 4 (Evaluation of extrusion processability) Using the vulcanized compositions of the polymers obtained in Examples 2 and 3, Garvey extrusion was performed under the extrusion conditions shown in Table 2 below to evaluate the moldability. Summer.

Claims (1)

[Scope of Claims] 1 A monomer mixture consisting of propylene, tetrafluoroethylene, alkyl vinyl ether, and optionally other comonomers is copolymerized by acting on a polymerization initiation source to obtain tetrafluoroethylene 52-80 Mol%, propylene 1
0 to 30 mol%, alkyl vinyl ether 10 to 38 mol%, and other comonomers 0 to 10 mol% as constituent units. A method of manufacturing fluoroelastomers. 2. The molar ratio of the monomer mixture at the start of polymerization is 80 to 97 mol%, 2 to 12 mol% for tetrafluoroethylene, propylene, and alkyl vinyl ether, respectively.
1 to 8 mol%, and the molarization of the charge monomers is 52 to 80 mol% of tetrafluoroethylene and 10 to 80 mol% of propylene.
30 mol%, alkyl vinyl ether 10-38 mol%
A manufacturing method according to claim 1. 3. The manufacturing method according to claim 2, wherein the emulsion polymerization is performed using a combination of ammonium persulfate and sodium acid sulfite as a polymerization initiation source, and the reaction temperature is 50 to 100°C. 4. The manufacturing method according to claim 2, wherein emulsion polymerization is performed using an ammonium persulfate-sodium thiosulfate-iron salt redox catalyst as a polymerization initiation source, and the reaction temperature is 0 to 50°C. 5. The manufacturing method according to claim 2, wherein the reaction pressure is 5 to 100 kg/cm^2 in gauge pressure. 6. The manufacturing method according to claim 1, wherein the alkyl vinyl ether is methyl vinyl ether. 7. The manufacturing method according to claim 1, wherein the alkyl vinyl ether is ethyl vinyl ether. 8. The manufacturing method according to claim 1, wherein the alkyl vinyl ether is n-butyl vinyl ether. 9. The method for producing a fluorine-containing elastomer according to claim 1, wherein the other comonomer is a monomer that forms a curing site. 10. The manufacturing method according to claim 9, wherein the monomer forming the cured site is glycidyl vinyl ether. 11 The number average molecular weight of the polymer is in the range of 30,000 to 100,000,
Its Mooney viscosity (100℃, ML_1_0) is 10~
The method for producing a fluorine-containing elastomer according to claim 1, which has a value of 70.