JPS6043845B2 - Heat treatment method for fluorine-containing elastomer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for heat treatment of fluorine-containing elastomers, and more specifically, the present invention relates to a method for heat treatment of fluorine-containing elastomers. The present invention relates to a heat treatment method for a fluorine-containing elastomer, which can improve moldability and adhesion and provide an excellent appearance by thermally decomposing the fluorine-containing elastomer and then subjecting it to vacuum treatment.

Propylene-tetrafluoroethylene copolymers, vinylidene fluoride-hexafluoropropylene copolymers, etc. are known as crosslinkable or vulcanizable fluorine-containing elastomers that exhibit excellent heat resistance and chemical resistance. .

Therefore, cross-linking aids, fillers, reinforcing agents, etc. are blended with the fluorine-containing elastomer, which is usually used, and cross-linked with a chemical cross-linking agent or ionizing radiation to produce various heat-resistant and chemical-resistant rubber products. It is used for a purpose. In order to take advantage of the heat and chemical resistance and rubber elasticity of fluorine-containing elastomers, products that are composited with various materials may be required, or continuous molding may be required using molding methods such as extrusion or transfer. many,
Particularly important are laminated composite products, complexly formed products, and irregularly shaped products.

According to the research of the present inventor, adhesives and adhesion technologies for fluorine-containing elastomers and various materials have not been sufficiently established. It is difficult to obtain fully satisfactory results with commercially available rubber adhesives, and many factors are recognized to increase costs, such as the use of special adhesives and the complexity of work. In addition, in the continuous molding process, problems may occur in the surface condition, cross-sectional shape, mold flowability, dimensional accuracy, etc. of the molded product.
Disadvantages are recognized, such as the inability to increase extrusion speed. In order to provide means for solving the above-mentioned problems, the applicant has conducted various studies and studies, and as a result, has developed a propylene-tetrafluoroethylene copolymer and a vinylidene fluoride-hexafluoride propylene copolymer. When a fluorine-containing elastomer made of an addition polymer such as a polymer is subjected to a specific thermal decomposition treatment in the presence of oxygen or with the addition of a basic oxide, it becomes difficult to contact with various substrates. It was previously discovered that the adhesion properties are improved, the moldability is improved, and the self-adhesion properties are also improved.

Specification of Japanese Patent Application No. 51-83973, Japanese Patent Application No. 1983-101
See specification No. 544, Japanese Patent Application No. 51-132348, etc. However, with just the thermal decomposition treatment as described above,
Various drawbacks are recognized, such as poor reproducibility in vulcanization adhesion with various base materials, and phenomena such as microfoaming often occurring on the surface of molded products and poor appearance of the surface finish.

As a result of further various studies based on this knowledge, the inventors of the present invention have found that, after the heat treatment as described above, the above-mentioned difficulties can be smoothly and advantageously solved by performing a depressurization treatment at a temperature that does not cause thermal decomposition. We found that it is possible to solve this problem. That is, by combining a specific decompression treatment after a specific thermal decomposition treatment,
It has been found that stable vulcanization adhesion with various base materials is possible, and the surface of the molded product can be finished smooth and the appearance can be improved. As a result, the post-treated heat-treated product can be used as an adhesive composite with various base materials, and can also be used smoothly and advantageously in continuous molding processing. It is also effective as a plasticizer or tackifier for improving the moldability of fluorine-containing elastomers, or as an adhesive medium between fluorine-containing elastomers and various substrates. Furthermore, the heat-treated product does not impair the heat and chemical resistance of the fluorine-containing elastomer, and can be used as an adhesive medium, a molding processability improver, or as a vulcanized molded product itself, advantageously exhibiting the excellent properties of rubber products. It is easy to maintain, and the surface finish of the product is good in appearance. Thus, the present invention has been completed based on the above findings, and is capable of producing a fluorine-containing elastomer having a molecular weight of 30,000 or more at a thermally decomposable temperature of 250 to 450°C, and which does not lose its elastic solid state. The object of the present invention is to provide a novel method for heat treatment of a fluorine-containing elastomer, which is characterized in that the heat treatment is carried out at a temperature within a range of 100% and then the reduced pressure treatment is carried out at a temperature that does not cause thermal decomposition.

In the present invention, the reason why the vacuum drying treatment after the thermal decomposition treatment improves the adhesion, moldability, etc. of the heat-treated fluorine-containing elastomer is that the weight reduction due to vacuum closely affects the adhesiveness and moldability. Because it is connected,
It is presumed that hydrofluoric acid, carbon dioxide gas, water, and other volatile low molecular weight substances are removed.

The above explanations are not intended to limit the present invention in any way, but are provided to facilitate understanding of the features of the present invention. In the present invention, it is important to combine the thermal decomposition treatment and the subsequent vacuum drying treatment.

Although it is preferable to have oxygen present during the thermal decomposition treatment, the heat treatment can also be carried out under an inert atmosphere such as in a nitrogen stream. The amount of oxygen present is not particularly limited as long as it is an effective amount during heat treatment, and normally the amount present when heat treatment is carried out in air is sufficient, and an excessively dilute or concentrated state may be disadvantageous in terms of industrial implementation. Become. The heating temperature may be within the temperature range at which the fluorine-containing elastomer can be thermally decomposed, and may range from 250 to 250℃ depending on the type of fluorine-containing elastomer to be treated
It can be selected from the range of ~450°C. Regarding the heat treatment time, if it is too short, the effect of the present invention will be reduced, and if it is too long, the excellent physical properties of the fluorine-containing elastomer will be impaired and there will be a risk of liquefaction. It is desirable to select the treatment time according to the heating temperature, and usually the higher the temperature, the shorter the treatment time. Normally, a heat treatment time of at least 1 powder and within a range that does not lose the elastic solid state is adopted, but in industrial implementation, it is recommended to select conditions of 24 hours or less, especially about 3 to 10 hours. It can be said to be economically advantageous. Therefore, in the present invention, it is desirable to add a small amount of basic oxide during the thermal decomposition treatment, since this can improve the efficiency of the thermal treatment.

That is, the heat treatment temperature can be lowered by about 20'C or more, compared to, for example, the case where no basic oxide is present. Usually, the amount of the basic oxide to be added may be selected at a ratio of about 0.01 to 5% by weight, preferably about 0.1 to 3% by weight, based on the fluorine-containing elastomer. If the amount added is too small, no effect will be observed, and if the amount added is too large, problems such as loss of the excellent physical properties of the fluorine-containing elastomer will be observed. Various basic oxides can be exemplified, such as magnesium oxide, calcium oxide, zinc oxide, copper oxide, silver oxide, tin oxide, lead oxide, barium oxide, and the like. Basic oxides suitable for the present invention include magnesium oxide, zinc oxide, calcium oxide, lead oxide, and the like. Further, these basic oxides do not necessarily have to be oxides having a specific valence of the metal; for example, in the case of lead oxide, lead monoxide, lead dioxide, lead tetroxide, etc. may be used. In the present invention, it is important to perform a drying treatment under reduced pressure following the thermal decomposition treatment described above. For example, drying under normal pressure cannot achieve the effects of the present invention, particularly the effects of stabilizing adhesive properties and improving the appearance of molded products.

The vacuum drying treatment temperature may be within a temperature range that does not substantially cause thermal decomposition of the fluorine-containing elastomer, and may be selected from the range of room temperature to 200° C. depending on the type of fluorine-containing elastomer to be treated. Regarding the depressurization treatment time, if it is too short, the effect of the present invention will be reduced, and if it is too long, it will be economically disadvantageous. It is desirable to select the treatment time according to the reduced pressure treatment temperature; normally, the higher the temperature, the shorter the treatment time. Normally, a processing time of at least 1 hour and less than 4 hours is adopted, but in industrial implementation, it is advantageous from the economical point of view to select conditions of 2 hours or less, especially between 30 minutes and 1 hour. I can say it. In addition, the degree of decompression during depressurization treatment is 10 in terms of mercury column.
07W or less, preferably about 5i town or less is adopted.
As the fluorine-containing elastomer to which the method of the present invention can be applied, a wide variety of fluorine-containing elastomers that are conventionally known or well-known may be used without particular limitation.

For example, propylene-tetrafluoroethylene copolymers, vinylidene fluoride-propylene hexafluoride copolymers, vinylidene fluoride-trifluorochloroethylene copolymers, vinylidene fluoride-propylene pentafluoride copolymers, Fluoroalkyl acrylate elastomer, fluorine-containing nitroso elastomer, fluorine-containing siloxane elastomer, tetrafluoroethylene-vinylidene fluoride-propylene copolymer, tetrafluoroethylene-ethylene-isobutylene copolymer, ethylene-hexafluoropropylene copolymers, tetrafluoroethylene-butene-1 copolymers, tetrafluoroethylene-ethyl vinyl ether copolymers, fluorine-containing phosphonitrile elastomers, tetrafluoroethylene-fluorovinyl ether copolymers, etc. Can be mentioned. The fluorine-containing elastomer used in the present invention usually has a number average molecular weight of 30,000 or more, preferably 50,000 to 480,000, particularly 100,000 to 250,000.

The high molecular weight fluorine-containing elastomer suitable for the present invention is one comprising an addition polymer such as a propylene-tetrafluoroethylene copolymer and a vinylidene fluoride-hexafluoropropylene copolymer. The suitable polymeric fluorine-containing elastomer is not particularly limited, and a wide range of examples can be used. For example, products manufactured by various polymerization methods such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization, catalytic polymerization methods using polymerization initiators, ionizing radiation polymerization methods, redox polymerization methods, etc. Various examples include those manufactured using the same method. Therefore, the preferred propylene-tetrafluoroethylene copolymer elastomer contains, in addition to the main components of tetrafluoroethylene and propylene, components that can be copolymerized with these, such as ethylene isobutylene, acrylic acid, and its alkyl ester, methacrylic acid and its alkyl ester, vinyl fluoride, vinylidene fluoride,
A propylene-tetrafluoroethylene copolymer suitably containing hexafluoropropylene, chloroethyl vinyl ether, chlorotrifluoroethylene, perfluoroalkyl vinyl ether, etc. may also be used.

The molar ratio of tetrafluoroethylene and propylene constituting the copolymer, the molar ratio of other components added as necessary, and the molecular weight of the copolymer are determined based on the target material to be treated. The material can be arbitrarily selected depending on the usage, heat and chemical resistance, elastic elastomer properties, ease of acquisition, etc. For example, in the present invention, the molar ratio of tetrafluoroethylene/propylene is 9.
9/1 to 10/90, preferably 95/5 to 30/70, considering the excellent heat resistance that is a feature of this copolymer.
In particular, propylene-tetrafluoroethylene copolymers having a ratio of 90/10 to 45/55 can be widely used. In addition, the content of the above-mentioned components other than the main components of tetrafluoroethylene and propylene is O to 50 mol%,
Preferably, about 0.5 to 40 mol% is employed.
Further, it is desirable to use a copolymer having a molecular weight of about 50,000 or more, and a copolymer having a moderately high molecular weight can provide advantageous applicability. For example, more than 70,000. Preferably, a propylene-tetrafluoroethylene copolymer having a molecular weight of about 100,000 to 250,000 may be used.
Also, as a suitable vinylidene fluoride-vinylidene hexafluoride copolymer elastomer, in addition to the main components of vinylidene fluoride and propylene hexafluoride, components that can be copolymerized with these, such as ethylene tetrafluoride, can be used. , perfluorovinyl ether, acrylic acid. and alkyl esters thereof, methacrylic acid and alkyl esters thereof, etc. may be appropriately contained therein.

The molar ratio of vinylidene fluoride/propylene hexafluoride is 95
/5-40/601 preferably 90/10-60/40
Vinylidene fluoride-6! Fluorinated propylene copolymers are widely used, and tetrafluoroethylene, perfluorovinyl ether, etc. are used in an amount of 0 to 40 mol%, preferably 1
About 0 to 30 mol% may be copolymerized. The molecular weight of the copolymer (b) is also preferably as high as possible, 50,000 or more, for example 70,000 or more, especially 10 to 10,000 as described above.
Approximately 250,000 people will be hired. The treated product obtained in the present invention can be advantageously used as an adhesive for bonding a high molecular weight fluorine-containing elastomer as described above to various substrates. In addition, it can of course be used as an adhesive between the same type of fluorine-containing elastomer or between different types of fluorine-containing elastomers. for example,
Metal base materials such as mild steel, stainless steel, cast iron, and brass; base materials such as cotton cloth, polyamide cloth, aromatic polyamide cloth, and polyester cloth; fluororesins such as polystrafluoroethylene and ethylene-tetrafluoroethylene copolymers: Other resins, glass fibers, asbestos, or various commercially available natural rubbers, synthetic rubbers, and other base materials can be used with fluorine-containing materials such as propylene-tetrafluoroethylene copolymers, vinylidene fluoride-hexafluoropropylene copolymers, etc. The treated product of the present invention can be advantageously employed as an adhesive when bonding elastomers to form a composite. Vulcanization adhesion with the various substrates described above is possible by using the treated product as a main adhesive agent and vulcanizing and blending the fluorine-containing elastomer described below.

For example, a peroxy compound and/or a polyfunctional compound, an amine compound, a polyhydroxy aromatic compound, etc. are blended into the treated product of the present invention, and the blend is used as an adhesive medium to attach a high molecular weight fluorine-containing elastomer to various base materials. Vulcanization bonding can be carried out. Therefore, the treated product of the present invention can be used as an adhesive for high molecular weight fluorine-containing elastomers as described above, and can also be used by appropriately blending various compounding agents described below.
It can be molded into molded products such as sheets, vibrators, rods, tubes, angles, and channels by continuous molding methods such as extrusion and transfer, and it can be molded into irregularly shaped products and special molded products by various other molding methods. For example, it can be molded into sponge-like rubber.

The processed product of the present invention formed in this manner can be made into a vulcanized product by an appropriate vulcanization method as described below. In this way, various fluorine-containing elastomer vulcanized rubber products can be obtained from the processed product of the present invention. Incidentally, the vulcanization formulation and vulcanization means described below can be similarly applied to the heat treatment and the high molecular weight fluorine-containing elastomer at the time of vulcanization adhesion. In the present invention, it can be converted into a vulcanizate by the action of a chemical crosslinking agent, ionizing radiation, etc. with an appropriate vulcanization mixture during molding or vulcanization adhesion as described above.

For example, a chemical crosslinking agent consisting of a peroxide compound can be employed, and specific examples include diacyl peroxide such as dibenzoyl peroxide, dicumyl peroxide,
Monoperoxy compounds such as peroxy esters such as di-t-butyl peroxide, t-butyl peroxyacetate, t-butyl peroxyisopropyl carbonate, t-butyl peroxybenzoate, and 2.
5-dimethyl-2,5-di(t-butylperoxy)
-Hexyne-3,2,5-dimethyl-2◆5-(t-butylperoxy)-hexane, α●α1-bis-(t-butylperoxy)-para-diisopropylbenzene,
Examples include diperoxy compounds such as 2●5-dimethyl-2,5-di(benzoylperoxy)-hexane. These may be used alone or in a mixture of two or more. The amount of chemical crosslinking agent used is usually 0 parts per 10 parts by weight of the treated product or high molecular weight fluorine-containing elastomer
．． 1 to 2 parts by volume, preferably about 1 to 1 part by volume is employed. Further, crosslinking can be effected 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 1σ to 1σ roentgen/hour, especially 103 to 5×107 L/hour, the irradiation dose is about 1σ to 1σ rat, especially 10
By irradiating with ionizing radiation in a range of about 5 to 07 rats, the treated product or the propylene-tetrafluoroethylene copolymer elastomer, etc. can be converted into a crosslinked copolymer. Therefore, it is possible to irradiate the air with ionizing radiation, and the irradiation atmosphere must be kept in a vacuum or in a atmosphere such as argon, helium, nitrogen, etc. It can be held under air flow or even underwater.
The crosslinking reaction caused by ionizing radiation irradiation proceeds efficiently at room temperature or around room temperature, so there is no need to particularly limit the irradiation temperature. It is also possible to use radiation temperature. In crosslinking using amines, so-called alkyl polyamines such as hexamethylene diamine, tetraethylene diamine, tetraethylene pentamine, and triethylene tetramine, or their salts such as carbamic acid and cinnamylidene acid, or piperazine, piperidine, pyridine, aniline,
Aromatic polyamines such as phenanthroline and their salts, as well as Schiff bases, reagents with nucleophilic properties such as hydroquinone and bisphemer A1 catechol, and their alkali metal salts, ammonium salts, etc., are used as appropriate in polypropylene glycol, etc. It is also possible to use a combination of linear polyethers and cyclic polyethers as auxiliaries.

When crosslinking a high molecular weight fluorine-containing elastomer or a treated product made of a propylene-tetrafluoroethylene copolymer, both methods using ionizing radiation irradiation and methods using chemical crosslinking agents are conventionally known or well known. A crosslinking aid such as the following 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,
Organic allyl compounds such as diallyl phthalate, triallyl phosphoric acid, triallyl cyanurate, triallyl isocyanurate, diallylmelamine, and oxime compounds such as parabenzoquinone dioxime, P4-P''-dibenzoylbenzoquinone dioxime are used, and especially allyl compounds It is desirable that the crosslinking aid be added in an amount of 0 to 10 parts by weight of the treated product or high molecular weight fluorine-containing elastomer.
. 1 to 20 parts by weight, preferably about 0.2 to 1 part by weight may be employed.

In the present invention, when crosslinking the vulcanized compound as described above, various additives commonly used in conventional crosslinking methods may also be added and blended 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, pigment pigments, antioxidants, stabilizers, and the like. Therefore, in the present invention, when blending the various additives as described above, it is desirable to mix the chemical crosslinking agent, crosslinking agent, and other additives sufficiently and uniformly.

Such mixing may be carried out using conventionally used rubber kneading rolls or Panbury mixers. Working conditions during mixing are not particularly limited, but usually 30
By kneading the powder at a temperature of about 80 DEG C. for about 10 to 6 minutes, the additive compound can be sufficiently dispersed and mixed in the treated product or the high molecular weight fluorine-containing elastomer. It goes without saying that various other additives may be mixed during the above mixing, or may be added and mixed before or after kneading. Note that it is desirable that the working conditions and operation during mixing be carried out by selecting optimal conditions according to the types and purpose of the raw materials and compounding agents used. 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 applying pressure in a mold is employed, or an operation of heating an unvulcanized compound under pressure after being press-fitted into a mold is employed, or an extrusion, calender roll, or injection molding method is employed. After shaping, heating in a heating furnace or steam cauldron may be employed. 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 is usually about 80 to 250°C, preferably 120 to 20°C.
A temperature of about 0°C may be adopted. Further, the heating time is not particularly limited, but is selected in the range of 3 minutes 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, reheating treatment may be employed at a temperature of 150 to 250C, preferably 180 to 2300C, for about 0.5 to 25 hours. When using the treated product for adhesion with various base materials, it is usually mixed with a vulcanizing agent, a vulcanizing aid, a filler, etc. as necessary.
~0.5? It is preferable to use it in the form of sheeting or dissolved in a suitable solvent.

Specifically, when the base material is metal, the adhesion surface is previously subjected to sound blasting or sound vapor treatment, and degreased with acetone, trichlorethylene, or steam.
After applying the adhesive once, usually by brushing, etc., it is dried by gentle heating at room temperature, preferably for 2 hours or more, or at 80° C. or less. After drying, an unvulcanized fluorine-containing elastomer compound is placed on the adhesive surface and vulcanization bonding is performed. Furthermore, when adhering to metal etc. by press-fit molding, a method of forming a strong coating film by applying heat treatment at 150 to 160°C x 1 powder after applying the treated product to the adherend is also an appropriate method. Adoptable.

In addition, if the base material is fibers such as cotton cloth, nylon, Tetron, etc., apply the adhesive directly to the base material, or immerse the fibers in the adhesive, dry with the same recipe as above, and then apply vulcanization bonding. .

If necessary, a so-called primer can be used on the base material side for these adhesives. Specific uses of adhesive composites with these various base materials include the following.

Adhesion to mild steel etc. is applied to rolls, gaskets, backings, hoses, diaphragms, etc. cotton cloth, nylon,
Diaphragms, hoses, fabrics, belts, etc. are processed using adhesion with Tetron, vinylon, etc. Furthermore, by using adhesion with fluororesin etc., wrapping gaskets, backings, etc. can be obtained, and by using adhesion with other types of rubber, various products such as rolls, hoses, etc. can be obtained. Next, embodiments of the present invention will be described in more detail, but it goes without saying that the present invention is not limited by such explanations.

Note that 1 adhesive strength used in the examples. is measured as follows. That is, to 100 parts by weight of a propylene/tetrafluoroethylene copolymer elastomer with a molar ratio of propylene/tetrafluoroethylene of 55/45N and a molecular weight of 180,000, α・α
2 parts by weight of 1-bis(tert-butylperoxy)-P-diisopropylbenzene, 3 parts by weight of triallyl isocyanurate
Using a compound containing 35 parts by weight of MT carbon and 35 parts by weight of MT carbon, the compound was vulcanized and adhered to the surface of the base material using a sample adhesive to prepare a sample that complied with the 90 degree peel test of JIS K63Ol, and the adhesive strength was determined. Measure. An annealed copper plate was used as a representative base material. In this), the conditions for vulcanization adhesion are a temperature of 16
The temperature was 0°C, the time was 3 times, and the pressing pressure was 120k91d. The 90-bar peel strength thus obtained is measured as the adhesive strength and is expressed in K9lcm. In addition, evaluation of moldability was based on external and internal observations of the press molded products. That is, when a 10 cm square sheet with a thickness of 2 mm was pressed and vulcanized, the defects on the surface, the presence or absence of foaming, and the presence or absence of foaming in the cross section were observed. Example 1 and Comparative Example 1 Average molecular weight 180,000, C2F4/C3H6 = 55/45 (
molar ratio) of propylene-tetrafluoroethylene copolymer,
After heat treatment at 360° C. for 2 hours in an air atmosphere in an electric furnace, it was dried under reduced pressure at 80° C. and 101 rrftHg for 8 hours.

100 parts by weight of the obtained treated product, peroximone FlOO8
[D, dl bis(tertiary butylperoxy)-P-diisopropylbenzene] (vulcanizing agent) 2 parts by weight, triallyl isocyanurate (vulcanization aid) 3 parts by weight, MT carbon 35 parts by weight were blended. A sheet-like vulcanized compound was prepared. This was sandblasted, degreased and washed, and a mild steel plate 1 was coated with a primer (AF-460G9, manufactured by Asahi Glass Co., Ltd.).
It was vulcanized and glued. On the other hand, for comparison, samples that were not subjected to vacuum drying were also subjected to exactly the same formulation and vulcanization adhesion. These results are summarized in Table 1 below.

Example 2 and Comparative Example 2 The same blended fabrics as in Example 1 and Comparative Example 1 were prepared, and a sheet of 27r$1110C1n square in thickness was prepared under breath vulcanization conditions of 1700C x 2Gin and pressure 100K91CIL.

The results are shown in Table 2 below. Example 3 After performing the same heat treatment as in Example 1, 4
Drying was carried out under a reduced pressure of 20 wtHg for an hour.

A steam heating type container with an internal volume of 1 d was used for drying under reduced pressure. The amount of heat treated polymer treated was 50 kg. This treated polymer was blended in the same manner as in Example 1 to produce 50 rubber-coated backings with mild steel as the base material (core) as shown in FIG. 1 of the attached drawings. As an adhesive, AF-
460G* and AF'360* were used together. (*All adhesives are made by Asahi Glass) Ten of them were randomly selected and the adhesive condition was examined, and all of them showed rubber breakage. Also,
Neither surface sagging nor foaming was observed. Example 4 After heat-treating vinylidene fluoride-propylene hexafluoride elastomer (Viton B) at 320'C for one hour,
The mixture was treated under reduced pressure at 90° C. and 2 g of mercury per turn.

For every 10 parts of this treated polymer, add 3 parts of Diac #3.
15 parts by weight of low-activity magnesia and 2 parts by weight of MT carbon were mixed, and the same test as in Example 3 was conducted, and 10 samples were prepared. Chemlock 607 as adhesive
(manufactured by Hyuson CO) was used. For comparison, we also made a heat-treated product and examined its adhesion and surface conditions. The samples that were only heat-treated had some areas with poor adhesion, but the samples that were subjected to post-treatment all had good adhesion. Example 5 1 part of magnesium oxide per 10 parts of tetrafluoroethylene-propylene copolymer (C2F4/C3H6 molar ratio = 55/45, number average molecular weight 180,000)
Parts by weight were blended and heat treated at 300°C for 20 hours.

The obtained heat-treated product was subjected to reduced pressure treatment at 150° C. under 5 Tr0 nHg for 1 hour. This treated polymer was formulated in the same manner as in Example 1 and vulcanized and bonded to a copy of a mild steel plate using AF-46?9, but all cases resulted in rubber breakage.

Example 6 The same polymer as in Example 1 was heat-treated at 320°C, and the resulting heat-treated product was heated to 150°C with 5 Hg
Below, the mixture was treated under reduced pressure for 1 hour.

The same formulation as in Example 1 was applied to this treated polymer, and a vulcanization adhesion test was conducted. As a result, all of the polymers showed rubber breakage.

[Brief explanation of the drawing]

FIG. 1 of the accompanying drawings schematically shows the shape of the mold used for the full press-fit type test.

Claims (1)

[Claims] 1. A fluorine-containing elastomer having a number average molecular weight of 30,000 or more.
After being heat-treated at a thermally decomposable temperature of 50 to 450°C for 15 minutes or more and within a range that does not lose its elastic solid state, the heat-treated fluorine-containing elastomer is subjected to reduced pressure treatment at a temperature that does not cause thermal decomposition. A method for heat treatment of a fluorine-containing elastomer. 2. The heat treatment method according to claim 1, wherein the temperature of the reduced pressure treatment is 50 to 200°C. 3. The heat treatment method according to claim 1 or 2, wherein the pressure of the reduced pressure treatment is 100 mm of mercury or less. 4. The heat treatment method according to claim 1, wherein the heat treatment is performed in the presence of oxygen. 5. The heat treatment method according to claim 1 or 4, wherein the heat treatment is performed with addition of a basic oxide. 6. The heat treatment method according to claim 1, 2, 3, 4, or 5, which uses a fluorine-containing elastomer made of an addition polymer. 7. The heat treatment method according to claim 6, which uses a fluorine-containing elastomer made of a propylene-tetrafluoroethylene copolymer. 8. The heat treatment method according to claim 7, which employs heat treatment conditions of 15 minutes to 24 hours at 250 to 450°C. 9. The heat treatment method according to claim 6, which uses a fluorine-containing elastomer made of a vinylidene fluoride-propylene hexafluoride copolymer or a vinylidene fluoride-propylene pentafluoride copolymer. 10. The heat treatment method according to claim 9, which employs heat treatment conditions of 15 minutes to 24 hours at 250 to 450°C. 11. The heat treatment method according to claim 6, which uses a fluorine-containing elastomer made of a vinylidene fluoride-trifluorochloroethylene copolymer. 12. The heat treatment method according to claim 11, which employs heat treatment conditions of 250 to 450°C for 15 minutes to 24 hours. 13 Claims 7 and 9 adopt heat treatment conditions of 15 minutes to 24 hours at 250 to 450°C in air,
Or the heat treatment method according to item 11.