JPH0118099B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a vulcanized composition of a fluorine-containing elastomer, more specifically, -O-(Q) _o -CF
The present invention relates to a novel vulcanized composition comprising a fluorine-containing elastomer having a specific side chain = CF ₂ and a specific vulcanizing agent. Elastic copolymers such as tetrafluoroethylene/propylene copolymers, vinylidene fluoride/hexafluoropropylene copolymers, and tetrafluoroethylene/perfluoroalkyl perfluorovinylether copolymers are heat resistant. is known as a vulcanizable fluorine-containing elastomer with excellent chemical resistance. In order to improve the vulcanization properties of such fluorine-containing elastomers,
Vulcanization sites include -COOH, reactive halogen,
Copolymerizing monomers with C=C double bonds that can react with sulfur (Japanese Patent Publication No. 43-24199)
Publications, U.S. Patent No. 3467635, etc.), -
Copolymerization of perfluorovinyl ethers such as COF, -CO ₂ R, -CO ₂ M
45-26303, etc.), or copolymerizing a bromine-containing olefin such as bromotrifluoroethylene (Japanese Patent Publication No. 53-4115, etc.). However, these known vulcanization sites cannot be said to be vulcanization sites that are advantageous for fully demonstrating the high heat resistance and chemical resistance that fluorine-containing elastomers inherently have. In addition, as a fluorine-containing polymer containing -C=CF ₂ , CF ₂ =CFCF ₂ CF=CF ₂ is combined with C ₂ F ₃ Cl and
Polymer copolymerized with C ₂ F ₂ H ₂
Publication No. 25437, etc.),

Polymers in which [formula] is copolymerized with CF ₂ = CFOCF ₃ and C ₂ F ₂ H ₂ are known (Japanese Unexamined Patent Publication No. 1983-35299), but the former is CF ₂ = CFCF ₂ CF = Since the reactivities of the two double bonds in CF ₂ are similar, it is questionable as a means to efficiently introduce a side chain containing CF=CF ₂ , and the latter is

The synthesis of the monomer of the formula is very complicated, so it cannot be called an economical method. Furthermore, in Japanese Patent Application Laid-Open No. 52-62386, C ₂ F ₄ /
CF ₂ = CFO(CH ₂ ) ₃ COOCH ₃ copolymer or C ₂ F ₄ /
A method is described in which a CF ₂ =CF-CF ₂ CF (CF ₃ ) COOCH ₃ copolymer is converted into a sodium salt and then heat-treated to convert the side chain into a specific perfluorovinyl group. The fluorine-containing polymer having a perfluorovinyl group obtained by this method can be used to introduce various functional groups using the perfluorovinyl group, or to use the vinyl group as a reaction site of a crosslinking monomer or as a grafting point for graft polymerization. It is said to be useful because it can be used to imitate people. The present inventor has developed an elastic polymer containing at least one polymerized unit of a fluorine-containing olefin, such as a tetrafluoroethylene/propylene copolymer, a vinylidene fluoride/hexafluoropropylene copolymer, and a tetrafluoroethylene/propylene copolymer. Various studies and studies have been conducted on fluorine-containing elastomers such as fluorinated ethylene/perfluoroalkyl perfluorovinyl ether copolymers in order to provide effective means for improving vulcanization properties. As a result, the specific -O-(Q) _o -CF=CF ₂ side chain is
It not only enables high-speed vulcanization of fluorine-containing elastomers, but also improves the physical properties of the vulcanizate.
It was discovered that it can exhibit advantages such as heat resistance, steam resistance, chemical resistance, and small compression set. Additionally, monomers that can provide specific side chains, e.g.
CH ₂ = CH―O― (Q) _o -CF=CF ₂ , CH ₂ =CH―
Vinyl ethers such as (CF ₂ ) _p -O-(Q) _o -CF=CF ₂ (p is an integer from 1 to 8), CF ₂ =CF-O-(Q) _o -CF=CF ₂ have two Since the reactivity of the double bonds is different, specific double bond side chains can be efficiently introduced into the fluorine-containing elastomer copolymer.
It has also been found that good vulcanization is possible with a combination of a vulcanizing agent made of a polyhydroxy aromatic compound and its accelerator. The present invention was completed based on the above findings, and contains at least one polymerized unit of a fluorine-containing olefin, and in addition to the above unit, -O--
(Q) _o −CF=CF ₂ (however, Q is a difunctional organic group,
0.1 vulcanizing agent made of a polyhydroxy aromatic compound per 100 parts by weight of a fluorine-containing elastomer made of an elastic polymer containing 0.05 to 10 mol% of polymerized additive units having a side chain (n is 0 or 1) ~
A vulcanized composition of a fluorine-containing elastomer, characterized in that it contains 10 parts by weight and 0.1 to 10 parts by weight of an accelerator such as a metal carboxylate salt, a polyol compound, a cyclic polyether, a phosphonium salt, or a quaternary ammonium salt. This is a new offering. In the present invention, the elastic polymer containing a specific proportion of additive units having specific side chains as vulcanization sites is not particularly limited as long as it is a polymer containing at least one polymerized unit of a fluorine-containing olefin. A wide range of examples can be given without
For example, suitable fluorine-containing elastomers include:
Ethylene tetrafluoride/propylene copolymer, ethylene tetrafluoride/perfluoroalkyl perfluorovinylether copolymer, vinylidene fluoride/propylene hexafluoride copolymer, vinylidene fluoride/propylene pentafluoride copolymer Other examples include vinylidene fluoride/ethylene trifluoride chloride copolymers, ethylene tetrafluoride/ethylene/isobutylene copolymers, ethylene/propylene hexafluoride copolymers, and ethylene tetrafluoride. /butene-1 copolymer, tetrafluoroethylene/ethyl vinyl ether copolymer, tetrafluoroethylene/CF ₃ NO copolymer, vinylidene fluoride/perfluoroalkyl perfluorovinylether copolymer, etc. It's okay if it's hot.
By incorporating an additive unit having a specific side chain into such a fluorine-containing elastomer, the vulcanization properties are greatly improved. The content ratio of the above-mentioned main component units in the fluorine-containing elastomer of the present invention can be selected over a wide range as long as it is an elastic polymer. For example 40-70 mol% tetrafluoroethylene and 60
Copolymer consisting of ~30 mol% propylene; 30~
Copolymer consisting of 95 mol% vinylidene fluoride, 70-5 mol% propylene hexafluoride, and 30-0 mol% ethylene tetrafluoride; 50-95 mol% ethylene tetrafluoride and 5-50 mol% Copolymer consisting of mol% perfluoroalkyl perfluorovinyl ether; 30
A copolymer consisting of ~95 mol% vinylidene fluoride and 70-5 mol% propylene pentafluoride may be exemplified. Of course, such fluorine-containing elastomers are
In addition to the main component unit and specific addition unit, it may further contain other units. That is, the tetrafluoroethylene/propylene copolymer is vinylidene fluoride,
May contain appropriate units from ethylene, isobutylene, acrylic acid and its alkyl esters, methacrylic acid and its alkyl esters, hexafluoropropylene, trifluorochloroethylene, chloroethyl vinyl ether, perfluoroalkyl vinyl ether, etc. etc. There is no particular reason to limit the molecular weight of the fluorine-containing elastomer, but it is usually about 20,000 or more, preferably 30,000 or more, particularly about 50,000 to 500,000. In the present invention, the fluorine-containing elastomer polymer as described above contains 0.05 to 10 mol% of polymerized additive units having a side chain of -O-(Q) _o -CF= _CF2 .
It is important that it is contained. Q is a difunctional organic group, and n is 0 or 1. Q is usually a bifunctional organic group having 1 to 7 carbon atoms, and is preferably a perfluorinated group. Further, Q may be linear or branched, and may contain one or more ether bonds. For example, Q is

[Formula] (where p is 0 or an integer of 1 to 2, q is 0 or 1, and Rf represents a bifunctional perfluoroalkylene group having 1 to 10 carbon atoms). It is preferable that p is 0 or 1, and Rf may be linear or branched. Usually, Rf with q=1 and 1 to 4 carbon atoms
The case of . Therefore, in the present invention,
Q is -CF ₂ - which corresponds to n=1 -O-
It is a particularly preferred embodiment to employ polymerized addition units with side chains CF ₂ CF=CF ₂ .
In addition, the content of the specific addition unit in the fluorine-containing elastomer copolymer is 0.05 to 10 mol% as described above.
However, it is preferably about 0.5 to 5 mol%.
If the content of specific additive units is too low,
The effect of improving vulcanization properties will not be observed, and if the amount is too high, it will have an adverse effect on the basic performance of the fluorine-containing elastomer, and it will also be disadvantageous in terms of ease of acquisition. The fluorine-containing elastomer of the present invention can be easily produced by copolymerizing a monomer providing the main component unit as described above and a monomer providing the specific addition unit. For example, the main component unit monomer is CH ₂ = CH-(CF ₂ ) _p -O-(Q) _o -CF=
It is possible to copolymerize additive unit monomers such as CF ₂ , CF ₂ =CF-O-(Q) _o -CF=CF ₂ in an appropriate ratio. For copolymerization reactions, various polymerization methods such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization can be adopted, including catalytic polymerization using free radical initiators, ionizing radiation polymerization, and redox polymerization. A polymerization method or the like may be employed as appropriate. In addition, in the present invention, the main component unit monomer
CF ₂ = CF-O-(Q) _o- (CF ₂ ) ₂ -Copolymerize monomers such as COONa in an appropriate ratio, and heat-treat the resulting copolymer at about 230-300°C for 5-10 minutes. It is also possible to selectively convert a --(CF ₂ ) ₂ --COONa group to a --CF=CF ₂ group by, for example, used in a preferred embodiment of the invention
CF ₂ = CF―O―(Q) _o −(CF ₂ ) ₂ ―COONa, CF ₂
=CF-O-(Q) _o -CF= _CF2 , _CH2 =CH-
Specific monomers such as (CF ₂ ) _p —O—(Q) _o —CF=CF ₂ can be produced by various means. For example, in the specification of Japanese Patent Application No. 53-70362 and the specification of Japanese Patent Application No. 53-86776, CF ₂ =CF-O-(Q) _o - (CF ₂ ) ₂ -
The method for producing COONa and CF ₂ =CF-O-(Q) _o -CF=CF ₂ is CH ₂ =CH-(CF ₂ ) _p -O-
(Q) _o −CF=CF ₂ etc. can be synthesized. That is, CF ₂ =CF-O-(Q) _o- as described in JP-A-52-105118, JP-A-52-78827, etc.
After hydrolyzing the ester (CF ₂ ) ₂ -COOR (R is an alkyl group) with HCl etc., it is reacted with NaOH,
It is possible to synthesize CF ₂ =CF-O-(Q) _o- (CF ₂ ) ₂ -COONa, which is thermally decomposed at a temperature of 230 to 400°C with a residence time of about 0.1 to 30 seconds. By doing so, it is possible to synthesize CF ₂ =CF-O-(Q) _o -CF=CF ₂ . Also, CF ₂ =CF-O
- (Q) _o - (CF ₂ ) ₂ - ROH to the acid fluoride called COF
The above-mentioned ester can be obtained by reacting an alcohol, or by directly reacting Na ₂ CO ₃ with the acid fluoride.
CF ₂ =CF−O−(Q) _o −(CF ₂ ) ₂ −COONa may be obtained. In addition, as stated in Special Publication No. 45-22327, After synthesis, partial thermal decomposition yields CF ₂ =CF-O-
It is also possible to obtain (Q) _o −(CF ₂ ) ₂ −COONa. Therefore, CH ₂ = CH - (CH ₂ ) _p - O - (Q) _o -
CF=CF ₂ can be synthesized by the following method. I(CF ₂ ) ₃ COF is synthesized by partial oxidation of I(CF ₂ ) ₄ I with oleum, after which ethylene is inserted under the action of a free radical initiator,
Obtain ICH ₂ CH ₂ (CF ₂ ) ₃ COF. To this, hexafluorinated propylene oxide is added using CsF and tetraglyme as a solvent,

After synthesizing [Formula], it undergoes esterification and potassium salting steps, and then undergoes a deHI reaction.

Obtain [formula]. By thermally decomposing this potassium salt under reduced pressure at 210-230°C, CH ₂ = CH (CF ₂ ) ₄ OCF = CF ₂
and so on. Furthermore, the fluorine-containing elastomer of the present invention is a fluorine-containing elastomer having a side chain such as -O-(Q) _o -(CF ₂ ) ₂ -COONa obtained by the method described in Japanese Patent Application No. 101456/1983. It can also be synthesized by heat-treating a hydrogenated copolymer to convert the side chain into a -O-(Q) _o -CF=CF ₂ side chain. -O-
(Q) _o −(CF ₂ ) ₂ —The fluorinated copolymer having a COONa side chain is CF ₂ =CF—O—(Q) _o − as described above.
(CF ₂ ) ₂ ―COONa, CH ₂ =CH― (CF ₂ ) _p ―O―
(Q) _o -(CF ₂ ) ₂ -O-(Q) _o can be obtained by copolymerizing a monomer such as COONa with a main unit monomer, or by the method described in Japanese Patent Publication No. 45-26303. -(CF ₂ ) ₂ -COF, -O-(Q) _o -
(CF ₂ ) ₂ -COOH, -O-(Q) _o -(CF ₂ ) ₂ -
A copolymer having a side chain such as COOR is obtained, and this is subjected to hydrolysis treatment, etc. to produce -O-(Q) _o -
(CF ₂ ) ₂ - It can also be obtained by converting it into COONa type. -O-(Q) _o - in the polymer
(CF ₂ ) ₂ -COONa side chain -O-(Q) _o -CF=CF ₂
The heat treatment for converting into side chains is usually carried out as follows. That is, the polymer was placed in a hot air circulating electric furnace set at an appropriate temperature of 200 to 300°C, and heated for 5 to 30 minutes.
A thermal decomposition reaction is caused by heating for about a minute. It is also efficient to carry out the thermal decomposition reaction while kneading the mixture under normal pressure or reduced pressure using a heating kneader. Furthermore, it is also possible to carry out the thermal decomposition reaction continuously using a heating extruder. The temperature and time settings for these heat treatments can be adjusted depending on the amount of polymer to be treated, the type of electric furnace, kneader, extruder, etc., equipment capacity such as capacity, air volume, etc., and the structure of the side chain undergoing thermal decomposition. For example, when a polymer having a side chain of -(CF ₂ ) ₃ COONa is treated by leaving it in an electric furnace, a treatment time of about 10 minutes at 250°C is sufficient. In either case, the polymer undergoes some gelation after heat treatment, but this does not interfere with molding, and the polymer can be easily rolled and molded. Various amines and hydroxy compounds that can react with perfluorovinyl groups are known, but aromatic polyhydroxy compounds in particular rapidly react with perfluorovinyl groups in polymers in the presence of an appropriate catalyst to form strong form a crosslink. As the aromatic polyhydroxy compound, hydroquinone, bisphenol A, hexafluorobisphenol A, PP'-bishydroxydiphenylmethane, etc. can be used. In addition, a wide variety of compounds can be used as accelerators, including linear polyols,
Representative examples include cyclic polyols, amines, amine salts, quaternary ammonium salts, and phosphonium salts.
Particularly suitable are linear or cyclic polyols, phosphonium salts, and quaternary ammonium salts. Further, for example, using hydroquinone as a vulcanizing agent,
When using a linear polyol as an accelerator, it is effective to keep the system weakly alkaline by adding an alkali metal salt of a weak acid. Methods known or known in the art, including these methods, can be used. The vulcanizing agent made of the polyhydroxy aromatic compound as described above may be blended in an amount of about 0.1 to 10 parts by weight, preferably about 0.5 to 5 parts by weight, per 100 parts by weight of the specific fluorine-containing elastomer. Also, the blending ratio of the accelerator is 100% of the specific fluorine-containing elastomer.
It can be selected from the range of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight. Accordingly, in the present invention, when adding the various additives described above to the specific fluorine-containing elastomer, it is desirable to mix the chemical crosslinking agent, crosslinking aid, and other additives sufficiently and uniformly. Such mixing may be carried out using a rubber kneading roll or a Banbury mixer that has been conventionally used. Although the working conditions during mixing are not particularly limited, the additive compound can be sufficiently dispersed and mixed into the fluorine-containing elastomer by usually kneading at a temperature of about 30 to 80°C for about 10 to 60 minutes. It is also possible to appropriately dissolve and disperse such additives in a solvent to form a suspension solution. Furthermore, so-called wet mixing, in which mixing is carried out in a medium from the beginning, is also possible. In such cases, a solution-like mixture can be obtained by using a mixer such as a roll, ball mill, or homogenizer.
Note that it is desirable that the working conditions and operations during mixing be carried out by selecting optimal conditions depending on the type and purpose of the raw materials and ingredients used. The fluorine-containing elastomer of the present invention can be produced into a sheet by suitably blending the various compounding agents described above and by continuous molding methods such as extrusion, transfer, roll coating, brushing, and impregnation in addition to conventional mold molding. It can be molded into molded products such as pipes, rods, tubes, angles, channels, drawn fabrics, and coated plates, and can also be molded into irregularly shaped products and special molded products such as sponge-like rubber by various molding methods. It can also be molded. The composition of the present invention thus molded can be made into a vulcanized product by an appropriate vulcanization method as described below. Thus, a vulcanized rubber product can be obtained from the fluorine-containing elastomer of the present invention. In the present invention, the operation for performing thermal crosslinking using a chemical crosslinking agent can be performed by conventionally conventional operations. For example, an operation of heating while pressurizing in a mold may be employed, or an operation of heating in a heating furnace or steam pot after molding by extrusion, calendar roll, or injection molding may be employed. It is desirable to select the optimum working conditions during thermal crosslinking depending on the raw materials and formulation used. The temperature during thermal crosslinking is usually 80 to 250
A temperature of about 120°C to 200°C may be employed. Further, the heating time is not particularly limited, but is selected in the range of 1 minute to 3 hours, preferably in the range of 5 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 product can also be employed, and is useful for improving physical properties. for example,
2 at a temperature of 150-250°C, preferably 180-230°C.
For example, reheating treatment for about 25 hours may be employed. The fluorine-containing elastomer used in the present invention has excellent heat resistance, chemical resistance, oil resistance, etc., and has improved vulcanization properties, so it can improve the strength, elongation, compression set, etc. of vulcanized products or rubber products. The mechanical properties and other properties are also good. Therefore, by utilizing such performance, it can be applied to a wide range of uses and purposes in various fields. Examples include heat-resistant and corrosion-resistant gaskets, packing, O-rings, oil-resistant sealing materials, heat-resistant rolls, steam-resistant gaskets, heat exchanger gaskets, heat-resistant and oil-resistant electric wires, and the like. Next, examples of the present invention will be described in more detail, but it goes without saying that the present invention is not limited by such description. Example 1 1160g deoxygenated water, 5.8g in autoclave
of C ₈ F ₁₇ COONH ₄ , 11.6 g of NaHPO ₄ 12H ₂ O,
11.6 g NaH ₂ PO ₄ 2H ₂ O, 2.9 g (NH ₄ ) ₂ S ₂ O ₈ , 0.75 g NaHSO ₃ , 102 g C ₂ F ₄ ,
7.56g C ₃ H ₆ and 7.54g CF ₂ =CFO
(CF ₂ ) ₃ Prepare COONa. Thereafter, the temperature is raised to 70°C to start polymerization. During polymerization, a mixed gas of C ₂ F ₄ /C ₃ H ₆ (molar ratio 55/45) and CF ₂ =CFO
Replenish ( _CF2 ) _{3CO2Na and} increase the reaction pressure to 23-23.5
Kg/cm ² was maintained. CF ₂ = CFO (CF ₂ ) ₃ ―CO ₂ Na
The supplementation was carried out as a 20% by weight aqueous solution. During a polymerization time of 4.75 hours, 145 g of C ₂ F ₄ , 50 g of
C ₃ H ₆ and 8.2 g of CF ₂ =CFO (CF ₂ ) ₃ CO ₂ Na were replenished. The resulting latex had a pH of 2 and a polymer concentration of 13.7% by weight. Polymer yield
The weight was 198 g, and the average polymerization rate was 36 g/hour. This copolymer was heat treated in nitrogen at 300°C for 10 minutes. As a result of this heat treatment _, changes in the _infrared absorption spectrum of the _copolymer as shown in _FIG .
It can be seen that it is selectively converted to ₂ = CF groups. In FIG. 1, the ... line shows the spectrum before heat treatment, and the line - shows the spectrum after heat treatment, respectively. ...The spectrum shown by the line shows a wide range around 1670 cm ^-1 .
A characteristic absorption of the RfCOONa group is seen, and in the spectrum indicated by -, a characteristic absorption of the -CF= _CF2 group is seen at 1780 cm ^-1 . To 100 parts by weight of the thus obtained copolymer elastomer having a side chain of -O-CF ₂ CF=CF ₂ ,
MT - 35 parts of carbon, 10 parts of magnesium oxide, 4 parts of polyethylene glycol (molecular weight 400), 2 parts of bisphenol monopotassium salt, 2 parts of hydroquinone
The vulcanization behavior was measured at 170° C. using a Cyulastometer (manufactured by Japan Synthetic Rubber Co., Ltd.). As a result, the minimum torque
0.5Kg-cm, maximum torque of 2.8Kg-cm, and 7 minutes to complete 90% vulcanization, indicating rapid vulcanization progress. When the compounded rubber was vulcanized using a press at 170°C for 20 minutes to form a 1 mm thick sheet, a vulcanized sheet with a good appearance without foaming, weld lines, or back clinding was obtained. This sheet was further heated to 170°C by step cure.
Increase the temperature by 20℃ (1 hour each), and finally
As a result of oven vulcanization at 230°C for 10 hours, the following measured values were obtained for the normal physical properties of the sheet. Tensile strength: 172Kg/cm ² Elongation: 210% 100% modulus: 55Kg/cm ² Also, pellets for compression set measurement were molded under the same conditions, and the permanent set after compression at 200℃ x 22 hours was measured. When measured, it was 22%.

[Brief explanation of drawings]

Figure 1 of the attached drawings shows the copolymer in Example 1 before heat treatment (...line) and after heat treatment (--
This shows the infrared absorption spectrum of (line).

Claims (1)

[Scope of Claims] 1 Contains at least one polymerized unit of a fluorine-containing olefin, and in addition to the above unit, -O-
(Q) _o −CF=CF ₂ (where Q is a difunctional organic group, n
is 0 or 1) per 100 parts by weight of a fluorine-containing elastomer made of an elastic polymer containing 0.05 to 10 mol% of polymerized additive units having a side chain of 0 or 1), a vulcanizing agent made of a polyhydroxy aromatic compound: ~
1. A vulcanized composition for a fluorine-containing elastomer, which contains 10 parts by weight and 0.1 to 10 parts by weight of an accelerator. 2. The vulcanized composition according to claim 1, wherein the fluorine-containing elastomer is a tetrafluoroethylene/propylene copolymer. 3. The vulcanized composition according to claim 1, wherein the fluorine-containing elastomer is a tetrafluoroethylene/perfluoroalkyl perfluorovinylether copolymer. 4. The vulcanized composition according to claim 1, wherein the fluorine-containing elastomer is a vinylidene fluoride/propylene hexafluoride copolymer. 5. The vulcanized composition according to claim 1, wherein the fluorine-containing elastomer is a vinylidene fluoride/propylene pentafluoride copolymer. 6. The vulcanized composition according to claim 1, wherein the side chain of the additive unit is -O-CF ₂ CF=CF ₂ . 7. The vulcanized composition according to claim 1, wherein the accelerator is at least one selected from linear or cyclic polyethers, phosphonium salts, and quaternary ammonium salts.