JPH06136218A - Curable fluorine-containing polymer composition and method for curing the same - Google Patents

Abstract

PURPOSE:To obtain the subject composition, holding excellent characteristics such as heat and chemical resistance possessed by a conventional fluorine- containing polymer and capable of providing a cured product having moldability and excellent mechanical characteristics by blending a specified fluorine- containing copolymer with a cross-linking agent. CONSTITUTION:The objective composition is obtained by blending (A) a fluorine- containing copolymer prepared by copolymerizing a perfluorodiene monomer of the formula: CF2=CFO(CF2CF(CF3)O)n(CF2)mCF=CF2 (n and m are 1-3) and other monomers containing at least a fluorine-containing monomer (preferably tetrafluoroethylene, etc.) with (B) a cross-linking agent. The component (A) is preferably prepared by radical-polymerizing the monomer raw materials in the presence of a free radical polymerization initiator such as di(fluoroacyl) peroxides at 0-100 deg.C. For example, triallyl cyanurate, 2,4,6-tris(1,1,2,2,3,3- hexafluoro-3-((trifluoroethenyl)oxy)propyl-1,3,5-triazine can be used as the component (B).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a curable fluoropolymer composition and a method for curing the same.

[0002]

2. Description of the Related Art Conventionally, polytetrafluoroethylene (PT) has been used as a fluoropolymer having excellent heat resistance and chemical resistance.
FE resin), tetrafluoroethylene / hexafluoropropylene copolymer (FEP resin), polychlorotrifluoroethylene (PCTFE resin), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA resin), ethylene / tetrafluoroethylene Copolymers (ETFE resins) and the like are known, but since these (co) polymers have a linear structure, they cannot maintain their shape at a certain temperature and flow. It has the disadvantages.

Examples of introducing a double bond into the side chain of a fluorinated copolymer are disclosed in JP-A-56-79142 and JP-A-5-79142.
6-84711, it is different from the present invention in the method of introducing a double bond and the method of crosslinking. These describe methods by thermal decomposition of the copolymer of the monomer of formula (2) or copolymerization of the monomer of formula (3). The former method is different in substance and method from the present invention, and the latter method is such that, as seen in JP-A-1-131215, such diene monomer having a small gap between double bonds does not undergo cyclopolymerization. Since it occurs preferentially, it is not a good method for introducing a double bond into the side chain. CF ₂ = CFOCF ₂ CF ₂ CO ₂ Na formula (2) CF ₂ = CFOCF ₂ CF = CF ₂ formula (3)

On the other hand, a method for obtaining a crosslinked perfluoropolymer during polymerization is disclosed in US Pat. No. 3,310,606 and Japanese Patent Laid-Open No. 62-59610 regarding the polymerization of perfluorodivinyl ether monomer. Since both of the two double bonds of the monomer have high polymerization reactivity, this polymer has a drawback that crosslinking occurs during the polymerization, which makes molding process difficult.

[0005]

In order to overcome the above-mentioned problems, the present invention has a moldability and an excellent mechanical property without deteriorating the excellent properties of the conventional fluoropolymer. It is an object of the present invention to newly provide a composition and a curing method which give a fluoropolymer cured product.

[0006]

Thus, according to the present invention, a double bond is introduced into a side chain of a polymer by copolymerizing a monomer having two double bonds having different reactivities to form a cross-linking agent. By compounding, a curable fluorine-containing composition which provides a cured product having easy heat treatment and post-treatment such as heat treatment or radiation treatment and having excellent heat resistance and chemical resistance is newly provided.

That is, the present invention is a copolymer of the perfluorodiene monomer of the formula (1) and at least one or more other monomers, and all of the other monomers or other monomers. Provided is a curable composition in which a cross-linking agent is mixed with a fluorocopolymer in which at least one kind of monomer is a fluoromonomer. CF ₂ = CFO (CF ₂ CF (CF ₃ ) O) _n (CF ₂ ) _m CF = CF ₂ Formula (1) (n and m are each independently an integer of 1 to 3)

The monomer used in the present invention has 5 or more carbon or oxygen atoms between two double bonds,
For example, as disclosed in JP-A-1-131215, when the number of carbon atoms or oxygen atoms between two double bonds is 2 to 4, cyclopolymerization to form a 5 to 6 membered ring is carried out. Due to the predominance, the introduction of double bonds into the side chain does not occur efficiently.

The monomer used in the present invention can be obtained, for example, by thermally decomposing the compound of formula (4) (JP-A-55-15410). CF ₂ = CFO (CF ₂ CF (CF ₃ ) O) _n (CF ₂ ) _m CF ₂ CF ₂ COOM Formula (4) (n and m are each independently an integer of 1 to 3, M is an alkali metal)

A method for producing a compound of formula (1) described in JP-A-1-143844, in which n = 1 to 3 and m = 2, is shown below.

[Chemical 1]

The perfluorodiene monomer used in the present invention may contain, as a synthetic by-product, a compound such as formula (5) to which hexafluoropropylene oxide is added in the reverse direction. CF ₂ = CFO (CF (CF ₃ ) CF ₂ O) _n (CF ₂ ) _m CF = CF ₂ formula (5) (n and m are each independently an integer of 1 to 3)

The monomer to be copolymerized with the perfluorodiene monomer used in the present invention is not particularly specified as long as it is radically polymerizable, but a fluorine-containing elastic material excellent in heat resistance and chemical resistance or From the viewpoint of providing a fluorine-containing resin, tetrafluoroethylene, hexafluoropropylene, perfluoro (allyl vinyl ether), perfluoro (butenyl vinyl ether), perfluoro (2,2-dimethyl-1,3-dioxole), Chlorotrifluoroethylene, vinylidene fluoride, 1,1-difluoro-2,2-dichloroethylene, 1,1,1,
3,3-Pentafluoropropylene, ethylene, vinyl chloride, perfluoronitrosomethane, perfluoro (alkyl vinyl ether), (perfluoroalkyl) ethylene and the like are used alone or in combination of two or more.
Further, the following perfluoromonomers, acrylic acid, acrylic acid esters, methacrylic acid esters, fluorine-containing alkyl acrylates, fluorine-containing alkyl methacrylates and the like can also be used in order to impart ion exchange ability and adjust the surface energy. . CF ₂ = CFO (CF ₂ CF (CF ₃ ) O) _n (CF ₂ ) _m CO ₂ R CF ₂ = CFO (CF ₂ CF (CF ₃ ) O) _n (CF ₂ ) _m SO ₂ F (n is 0 To an integer of 3, m is an integer of 1 to 3, R is an alkyl group such as a methyl group or an ethyl group)

Radical polymerization is used as a polymerization method. That is, the polymerization method is not particularly limited as long as it radically proceeds, but bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization can be used. As the polymerization initiator used in the present invention, a free radical polymerization initiator is preferable, and examples thereof include di (fluoroacyl) peroxides, di (chlorofluoroacyl) peroxides, dialkylperoxydicarbonates,
Examples thereof include diacyl peroxides, peroxyesters, azobis compounds, persulfates and the like. Examples of the polymerization medium include freons such as freon 11 and freon 113 in solution polymerization, t-butanol, and the like. In suspension polymerization and emulsion polymerization, water or a mixed medium with another solvent as described above is used. The polymerization temperature can be selected from the range of 0 to 100 ° C. The polymerization pressure varies depending on the monomer used, but can be selected from the range of 0.5 to 30 kg / cm ² G for copolymerization with tetrafluoroethylene, for example.

Since the copolymer thus obtained by polymerization has a highly reactive double bond in the side chain, it is necessary to cure the copolymer by heat treatment, radiation treatment or the like after blending a crosslinking agent. Is possible.

The fluorine-containing polymer of the present invention can be crosslinked by various blending, and for example, it can be crosslinked by using a radical generating source. An azobis compound or a peroxy compound can be used as a radical generating source. And as a peroxy compound, various can be illustrated. For example, dibenzoyl peroxide, diacyl peroxide such as diperfluoropropionyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t
-Monoperoxy compounds such as peroxyesters such as -butylperoxyacetate, t-butylperoxyisopropyl carbonate, t-butylperoxybenzoate, and 2,5-dimethyl-2,5-di-
(T-Butylperoxy) -hexyne-3,2,5-dimethyl-2,5-di (t-butylperoxy) -hexane, α, α′-bis- (t-butylperoxy) -p-
Diisopropylbenzene, 2,5-dimethyl-2,5-
Examples thereof include diperoxy compounds such as di- (benzoylperoxy) -hexane. These may be used alone or in combination of two or more. The addition amount of such a chemical crosslinking agent is usually 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of the fluoropolymer.

As the cross-linking agent having a plurality of double bonds, a polyallyl compound having two or more allyl groups (CH ₂ = CHCH _2- ) or a trifluorovinyloxy group (CF ₂ = CFO-) is used.
Examples thereof include perfluoropolyvinyl ether compounds having at least one. Examples of the polyallyl compound include polyallyl-substituted alkyl or aromatic amines such as glycerin diallyl ether, diallylamine, and triallylamine, polyallyl-substituted phosphoric acid or phosphorous acid represented by triallyl phosphoric acid, and diallyl succinate. , Polyallyl substitution products of carboxylic acids such as diallyl adipate and diallyl phthalate, diallyl melamine, triallyl cyanurate, triallyl isocyanurate and the like. These may be used alone or in combination of two or more. As a preferred specific example, triallyl cyanurate, triallyl phosphate, triallyl isocyanurate,
Examples thereof include diallyl phthalate and diallyl melamine. Further, a crosslinking agent having a plurality of fluorine-containing allyl groups such as Chemical formula 2 (see JP-A-60-197712) can also be exemplified.

[Chemical 2]

As the compound having a plurality of trifluorovinyloxy groups, the compounds listed in Chemical formulas 3 and 4 can be used. The amount of the crosslinking agent added is 0.1 to 100 parts by weight, based on 100 parts by weight of the fluoropolymer,
Preferably about 0.2 to 50 parts by weight can be adopted.

[Chemical 3]

[Chemical 4]

The cross-linking agent of formula (6) can be synthesized by the synthetic route of Chemical formula 5.

[Chemical 5]

The cross-linking agent of formula (7) can be synthesized by the synthetic route of Chemical formula 6.

[Chemical 6]

The method of synthesizing the compound of formula (8) is described in the literature (R. Su.
llivan, J. Org. Chem., Vol.34, p1841-1844, (1969))
It is described in.

When the fluorine-containing polymer of the present invention is crosslinked, various additives usually used in the conventional crosslinking method may be added and blended. These additives include metal oxides such as magnesium oxide and lead oxide, metal hydroxides such as calcium hydroxide, reinforcing agents such as carbon black, fine silica, clay and talc, other fillers, pigments, and oxides. Including inhibitors, stabilizers and the like.

The heat treatment temperature of the curable composition containing a radical generating source is suitably 100 to 300 ° C., preferably 1
It is selected from the range of 50 to 250 ° C. Further, the curable composition of the present invention can be cured by radiation such as electron beam, ultraviolet ray and γ ray, and these methods may be used in combination. In the case of UV curing, a photopolymerization initiator may be added if necessary. The method of radiation treatment is useful in the field of electric wire coating with a fluoropolymer, and electron beam irradiation is preferably used.

It is also possible to crosslink using a compound having a plurality of amino groups and hydroxyl groups capable of reacting with a perfluoro unsaturated group. In particular, aromatic polyhydroxy compounds react rapidly with perfluorounsaturated groups in the polymer in the presence of a suitable catalyst to form strong crosslinks.

As the aromatic polyhydroxy compound, hydroquinone, bisphenol A, hexafluorobisphenol A (bisphenol AF), p, p'-bishydroxydiphenylmethane and the like can be used. Also,
A wide variety of compounds can be used as the accelerator, and typical examples thereof include linear polyols, cyclic polyols, amines, amine salts, quaternary ammonium salts, and phosphonium salts.
In particular, linear or cyclic polyols, phosphonium salts,
Quaternary ammonium salts are preferred. Furthermore, for example,
When hydroquinone is used as a crosslinking agent and a linear polyol is used as an accelerator, a method of keeping the system weakly alkaline by adding an alkali metal salt of a weak acid or the like is effective. Methods known or known in the art including these methods can be used.

As the compound having an amino group, hexamethylenediamine carbamate, N, N'-dicinnamylidene-1,6-hexadiamine, 4,4'-bis (aminocyclohexyl) methane carbamate and the like can be used. The crosslinking conditions when using a compound having an amino group are 100 to 400 ° C., preferably 150 to 250.
The temperature is preferably 1 second to 48 hours.

The crosslinking agent comprising the polyhydroxy compound or the compound having an amino group as described above is used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the specific fluoropolymer. Can be blended in amounts. The accelerator may be used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the specific fluoropolymer.

In the fluoropolymer of the present invention, the polymer unit based on the perfluorodiene monomer is 0.01
Those which are contained in a proportion of not less than mol% are preferable. If the proportion of the polymerized units is too small, it will be difficult to obtain a cured product which is the object of the present invention. The upper limit is not particularly limited, but it is sufficient if the content is 40 mol%. The balance is a unit based on a radical-polymerizable monomer, but the unit based on a fluorine-containing monomer (including a perfluorodiene monomer) in the polymer is 50 mol% or more. It is preferable because a fluoropolymer having excellent properties and heat resistance or a cured product thereof can be obtained.

In the present invention, when the above-mentioned various additives are added to a specific fluoropolymer, a crosslinking agent,
It is desirable to mix the accelerator and other additives sufficiently uniformly. Such mixing can be performed by a conventionally used rubber kneading roll, a Banbury mixer, an extruder, or the like. Further, one or both of the specific fluoropolymer and the additive may be dissolved or dispersed in an appropriate solvent and mixed, and the solvent may be distilled off. roll,
A mixer such as a ball mill or a homogenizer may be used.

With respect to the molecular weight of the fluoropolymer used in the present invention, it can be used in a range from liquid at room temperature to solid at room temperature and exhibiting melt fluidity at high temperature. The low molecular weight substance can be used as a raw material for rubber, and a substance that is solid at room temperature but exhibits melt fluidity at high temperature provides a molding material having both thermoplasticity and thermosetting property and excellent moldability.

The present invention can be widely applied from rubber to resin by selecting the copolymer composition. To prepare a cured rubber, a perfluorodiene monomer used in the present invention is added to a conventionally known polymerization composition in an appropriate amount and copolymerized, and a crosslinking agent and the like are added, followed by heat treatment or radiation treatment. It is possible to harden it with the like. For example, by containing a perfluoro (alkyl vinyl ether) in an amount of 10 to 40 mol% and a perfluorodiene monomer in an amount of 0.01 to 20 mol% and curing a terpolymer with tetrafluoroethylene (the balance), elasticity is obtained. You can get the body. On the other hand, in the field of resins, it is possible to prepare a copolymer having both thermoplasticity and thermosetting property, which exhibits thermoplasticity in a temperature range lower than the thermosetting temperature by selecting the composition and the molecular weight. .

When a perfluorinated copolymer is synthesized by using a completely fluorine-substituted monomer as a radically polymerizable monomer in both rubber and resin, and a perfluoro compound is used as a crosslinking agent, It is characterized in that a perfluoro curable composition can be prepared. When such a perfluoro copolymer is sufficiently cured, a cured product of perfluoro having excellent heat resistance and chemical resistance can be obtained.

Particularly, the fluorine-containing polymer to be blended is a copolymer of the perfluorodiene monomer of the formula (1) and tetrafluoroethylene, and the units based on each of them are 0.
When the content is 01 to 40 mol% and 99.99 to 60 mol%, the cured product has well-balanced mechanical properties and resistance to various chemicals. In this case, it is preferable that the fluorinated polymer in the uncured state is solid at room temperature and has a molecular weight such that it exhibits fluidity at high temperature. Those that are not solid at room temperature have poor molding workability. The preferable molecular weight for heat molding depends on the curing temperature and the molding temperature, but the volume flow rate (measured according to the method shown in Examples)
Is a value of 0.1 to 1000 mm ³ / sec at a temperature of 20 to 300 ° C. using a load of 5 to 50 kg.

[0033]

【Example】

Example 1 Synthesis of Copolymer CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF in a 100 cm ³ autoclave
₂ CF ₂ CF = CF ₂ (hereinafter abbreviated as PGBV) 24.4 g, Freon 113 (1,1,2-trichlorotrifluoroethane) 20.6 g, diisopropyl peroxydicarbonate 45 mg, methanol 0.09 g After charging, cooling with liquid nitrogen and degassing, the pressure was maintained at 7 kg / cm ² G while successively adding tetrafluoroethylene at 40 ° C. After reacting for 16 hours, reprecipitation was repeated 3 times with carbon tetrachloride and vacuum drying was performed at 60 ° C. to obtain 6.8 g of a copolymer. In the infrared absorption spectrum, strong absorption due to a double bond in the side chain was observed at 1788 cm ^-1 . The volume flow rate of the obtained copolymer was measured using a flow tester (manufactured by Shimadzu Corporation). When measured using a die having a diameter of 1 mm and a length of 2 mm at 170 ° C. and a load of 10 kg, the volumetric flow rate was 4.
It was 7 mm ³ / sec. When the composition of the copolymer obtained by the polymerization was examined by ¹⁹ F-NMR, the proportion of PGBV was 12 mol%.

Curing test Tetrafluoroethylene and P obtained as described above
Triallyl isocyanurate was used as a GBV copolymer in a small extruder at a weight ratio of 10: 1 at 160 ° C.
Mixed in. After making a press film with a thickness of about 0.5 mm at 170 ° C., the electron beam was applied to 5, 20, 50, 100
Irradiated with Mrad. The tensile elastic moduli at 25 ° C. are 9.8 × 10 ⁸ , 2.8 × 10 ⁹ and 4.8 × 10, respectively.
^{It was 9} and 7.2 × 10 ⁹ dyn / cm ² . 200 ° C
However, the sample irradiated with the electron beam did not melt and flow, and the values of tensile elastic modulus were 2.7 × 10 ⁷ , 1.3 × 10 ⁸ , and
The values were 3.1 × 10 ⁸ and 4.9 × 10 ⁸ dyn / cm ² . Since there is no melt fluidity and the decrease in elastic modulus is small in the high temperature region, it can be seen that crosslinking is proceeding. For example, a sample irradiated with 20 Mrad at 150 ° C. and 200
The elastic moduli at ℃ and 250 ℃ are 1.8 × 10 respectively
^The values were ⁸ , 1.3 × 10 ⁸ and 1.1 × 10 ⁸ dyn / cm ² .

Example 2 A binary copolymer of tetrafluoroethylene and PGBV synthesized in the same manner as in Example 1 (volume flow rate 127 mm ³ /
2,4,6-Tris (1,1,2,2,3,3-hexafluoro-3-) per second at 130 ° C and a load of 30 kg.
((Trifluoroethenyl) oxy) propyl) -1,
3,5-triazine (compound of formula (6) in the specification)
Were mixed in a weight ratio of 10: 3 at 100 ° C. using a small extruder. The elastic modulus at 25 ° C. when irradiated with electron beams of 30 and 50 Mrad is 2.5 × 10 5, respectively.
⁸ and 1.1 × 10 ⁹ dyn / cm ² , and the elastic moduli at 200 ° C. are 2.5 × 10 ⁷ and 4.6 × 10, respectively.
^{It was 7} dyn / cm ² . The elastic modulus of the sample irradiated with 50 Mrad at 150 ° C., 200 ° C., and 250 ° C. was 6.5 × 10 ⁷ , 4.6 × 10 ⁷ , and 2.8 × 1, respectively.
It was 0 ⁷ dyn / cm ² . It can be seen that there is no melt fluidity, and the change in elastic modulus in the high temperature region is small, indicating that crosslinking occurs.

[0036]

By curing the composition of the present invention, a fluoropolymer cured product having both moldability and excellent mechanical properties can be obtained without impairing the excellent properties of conventional fluoropolymers. To be

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Claims (4)

[Claims] 1. A copolymer of a perfluorodiene monomer of the formula (1) and at least one or more other monomers, wherein all of the other monomers or other monomers are included. A curable composition comprising a fluorine-containing copolymer, at least one of which is a fluorine-containing monomer, and a crosslinking agent. CF ₂ = CFO (CF ₂ CF (CF ₃ ) O) _n (CF ₂ ) _m CF = CF ₂ Formula (1) (n and m are each independently an integer of 1 to 3) 2. The curable composition according to claim 1, wherein the crosslinking agent contains an organic compound having a plurality of vinyl groups. 3. The curable composition according to claim 1, wherein the fluorocopolymer is a perfluorocopolymer. 4. A curing method, which comprises subjecting the curable composition of claim 2 to radiation treatment.