JP2541183B2 - Amorphous fluorine-containing copolymer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-crystalline fluorine-containing copolymer having good oil resistance, heat resistance and low temperature properties.

[0002]

2. Description of the Related Art Conventionally, a binary copolymer of vinylidene fluoride and hexafluoropropylene or a terpolymer of tetrafluoroethylene added thereto has been used as a fluororubber excellent in heat resistance, oil resistance and chemical resistance. , Packing,
It has been used in various applications such as diaphragms and hoses. However, these copolymers become brittle when attacked by these chemicals in some applications such as contact with alkalis or amines, or contact with engine oil, and sometimes lose the function of fluororubber. It has a drawback that it will end up.

As a fluorine-containing elastic copolymer showing sufficient durability against alkalis and amines, and various oils, a binary copolymer of tetrafluoroethylene and perfluorovinyl ether, ethylene and perfluoroethylene. A binary copolymer of fluorovinyl ether, a ternary copolymer of tetrafluoroethylene, ethylene and perfluorovinyl ether (Japanese Patent Laid-Open No. 62-15212) or a binary copolymer of tetrafluoroethylene and propylene has been proposed. ing. However, a copolymer containing perfluorovinyl ether has a complicated monomer synthesis process,
As a result, a high-cost elastic copolymer is obtained, and it cannot be said that the demands of those skilled in the art are sufficiently satisfied.

On the other hand, the binary copolymer of tetrafluoroethylene and propylene contains a problem in oil resistance because it is contained in a relatively large amount of propylene, and at the same time, it loses flexibility at low temperature and becomes unreliable at low temperature. It cannot be used effectively when long-term durability is required.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a non-crystalline fluorine-containing copolymer which is relatively inexpensive, has durability against various lubricating oils, especially engine oils, and has good heat resistance and low temperature characteristics. It is an attempt to provide coalescence.

[0006]

The present invention is directed to 10 to 50 mol% of tetrafluoroethylene, the formula: CH ₂ ═CHOCH ₂ (CF ₂ ) nX (I) [wherein X is halogen or hydrogen and n is 2 ~ Represents a number of 8. ] The amorphous fluorocopolymer having a number average molecular weight of 1,000 to 1,000,000 and comprising 15 to 60 mol% of fluorovinyl ether and 10 to 50 mol% of ethylene. Further, the present invention provides (a) 10 to 50 mol% of tetrafluoroethylene, a formula: CH ₂ ═CHOCH ₂ (CF ₂ ) nX (I) [wherein, X is halogen or hydrogen, and n is a number of 2 to 8]. Represent 100 parts by weight of an amorphous fluorine-containing copolymer having a number average molecular weight of 1,000 to 1,000,000, comprising 15 to 60 mol% of fluorovinyl ether and 10 to 50 mol% of ethylene, and (B) A composition comprising 0.05 to 10 parts by weight of an organic peroxide compound is provided.

By copolymerizing ethylene, cold resistance can be further improved without sacrificing other properties.

The fluorovinyl ether (I) contained in the fluorine-containing copolymer of the present invention can be obtained, for example, from British Patent No. 73.
It is a compound known from No. 9,731 and can be easily synthesized, for example, by an ester / ether exchange reaction of vinyl acetate and a suitable fluoroalcohol. Specific examples of the fluoroalcohol include H (CF ₂ ) ₂ CH ₂ OH and H (CF ₂ ).
₄ CH ₂ OH, H (CF ₂ ) ₈ CH ₂ OH, CF ₃ CF ₂ CH ₂ O
H, F (CF ₂ ) ₈ CH ₂ OH, Cl (CF ₂ ) ₂ CH ₂ OH, Cl
(CF ₂ ) ₈ CH ₂ OH and the like are preferred.

In the fluorovinyl ether (I), the number of n is 2-8, preferably 4-6. When the number of n is smaller than 2, the low temperature characteristic of the copolymer tends to be sacrificed, and when the number of n is larger than 8, the copolymerization reaction rate decreases.

Specific examples of the fluorovinyl ether (I) include CH ₂ ═CHOCH ₂ (CF ₂ ) ₂ H, CH ₂ ═CHOCH ₂ (CF ₂ ) ₄ H, CH ₂ ═CHOCH ₂ (CF ₂ ) ₆ H and CH. _{2 = CHOCH 2 (CF 2)} 8 H, CH 2 = CHOCH 2 (CF 2) 2 F, CH 2 = CHOCH 2 (CF 2) 4 F, CH 2 = CHOCH 2 (CF 2) 6 F, CH 2 = _{CHOCH 2 (CF 2) 8 F} , CH 2 = CHOCH 2 (CF 2) 2 Cl, CH 2 = CHOCH 2 (CF 2) 4 Cl, CH 2 = CHOCH 2 (CF 2) 6 Cl, CH 2 = CHOCH 2 (CF ₂ ) ₈ Cl and the like.

Fluorovinyl ether (I) is an important monomer that imparts flexibility to the present copolymer, and if the proportion is less than 10 mol%, the proportion of the non-crystalline portion is reduced and the flexibility is increased. It is not preferable because it becomes a copolymer lacking in properties. On the other hand, if the proportion is too large, the polymerization rate will decrease, and it will be difficult to obtain a high molecular weight copolymer that is suitable for practical use.

In the present invention, in addition to the above-mentioned monomer,
As the copolymerizable monomer, for example, CF ₂ ═CFCl, CF ₂ ═CFCF ₃ , CH ₂ ═CXRf, CF ₂ ═CFO (CF ₂ CF ₂ ) mCH ₂ I, CF ₂ ═CFO (CF ₂ ) mCN, CF _{2 = CFO (CF 2) mBr} , CF 2 = CFO (CF 2) mI CH 2 = CHOR 1 CH 2 = CHOCH 2 CH 2 Cl CF 2 = CFCF 2 COOH

[0013]

Embedded image

[In the above formula, X is hydrogen or fluorine, Rf is a fluoroalkyl group having 1 to 12 carbon atoms, and R ¹ is ¹ carbon atom.
~ 12 alkyl groups, m is an integer of 1-8. ] CF ₂ = CF-OA ¹ p-A ² q-A ³ [wherein A ¹ is

Embedded image A ² is -CF ₂ CF ₂ CF ₂ O- or -CH ₂ CF ₂ CF ₂
O-, A ³ is _{- (CF 2) 2 CH 2} X 1 (. However, X ¹ is a halogen atom) or a perfluoroalkyl group having 1 to 5 carbon atoms, p and q are the 1 ≦ p + q ≦ 5 It is a satisfying number. ] May be used. The amount of these copolymerizable monomers is
It is preferably 30 mol% or less of the copolymer.

The amorphous copolymer of the present invention generally has an intrinsic viscosity of 0.01 to 10.00 and a number average molecular weight of 1,000.
~ 1,000,000, preferably 10,000-500,
It can be produced by various polymerization methods such as emulsion polymerization, suspension polymerization and bulk polymerization. Further, the monomer charging system is a batch system,
Alternatively, a system may be used in which additional charging is continuously performed so that the molar ratio of the monomers in the reaction system is kept constant. The polymerization is carried out by radical polymerization in the presence of a polymerization initiator used for the conventional polymerization of fluorine-containing olefins.

Examples of the polymerization initiator include persulfates such as ammonium persulfate, persulfates and sodium sulfite,
Inorganic peroxides such as redox initiators with reducing agents such as acidic sodium sulfite and, if necessary, promoters such as ferrous sulfate, copper sulfate and silver nitrate; diisopropyl peroxydica carbonate, isobutyryl peroxide , Benzoylperoxide, acetylperoxide, t-butylhydroperoxide and other organic peroxides; [CI
_{(CF 2 CFCI) 2 CF 2} COO-] 2, [H (CF 2 CF 2) 3
COO-] ₂ , [CICF ₂ CF ₂ COO-] ₂ ,

Embedded image And the like, such as fluorine-based peroxides.

When the emulsion polymerization method is adopted, the emulsifier is represented by the general formula: Y (CF ₂ ) mZ (II) [wherein Y is hydrogen or fluorine, Z is —COOH or —SO ₃ H, and m is 5 Represents a number from -12. ] The alkali metal salt or ammonium salt of the compound represented by the above is usually 0.1 to 5% by weight, preferably 0.5 to 2% by weight with respect to water.
It is preferable to add about wt%.

In the case of suspension polymerization, water is usually used as the polymerization medium, but with water 1,1,2-trichloro-1,2,
2-trifluoroethane, 1,2-dichloro-1,1,2,
Fluorine-based hydrocarbons such as 2-tetrafluoroethane, perfluorocyclobutane, dichlorodifluoromethane and trichlorofluoromethane can also be used.

Although the polymerization temperature is determined by the decomposition rate of the polymerization initiator, it can usually be selected from the temperature range of 0 to 150 ° C. The polymerization pressure is determined by the polymerization temperature and the polymerization method, but is usually selected from the range of 0 to 50 kg / cm ² G.

The molecular weight can be adjusted by adjusting the relationship between the copolymerization rate and the amount of the initiator, but it can be easily performed by adding a chain transfer agent. Examples of the chain transfer agent include hydrocarbons having 4 to 6 carbon atoms, alcohols, ethers and organic halides (for example, CCl ₄ , CBr).
Cl ₃ , CF ₂ BrCFBr-CF ₃ , CF ₂ I ₂ ) and the like can be advantageously used.

The amorphous copolymer of the present invention can be cured in the presence of various crosslinking sources. As the cross-linking source, radiation (α-ray, β-ray, γ-ray, electron beam, X-ray, etc.), high-energy electromagnetic waves such as ultraviolet rays can be used, but an organic peroxide compound is preferably used.

The amount of the organic peroxide compound used is 0.05 to 10 parts by weight, preferably 1.0 to 5 parts by weight, based on 100 parts by weight of the copolymer. As the organic peroxide compound, generally, a compound which easily generates a peroxy radical in the presence of heat or a redox system is preferable, for example, 1,1-bis (t-butylperoxy) -3,5,5. -Trimethylcyclohexane, 2,5-dimethylhexane-2,5
-Dihydroperoxide, di-t-butylperoxide, t-butylcumylperoxide, dicumylper
Oxide, α, α'-bis (t-butylperoxy) -p-
Diisopropylbenzene, 2,5-dimethyl-2,5-di
(t-butylperoxy) hexane, 2,5-dimethyl-
2,5-di (t-butylperoxy) -hexyne-3, benzoylper-oxide, t-butylperoxybenzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylper- Examples thereof include oxymaleic acid and t-butylperoxypropyl ether carbonate. Especially preferred are the diaryl type. Generally, the type and amount of the peroxide used are selected in consideration of the amount of active —O—O—, the decomposition temperature and the like.

When an organic peroxide compound is used, a remarkable curing can be observed by appropriately using a crosslinking aid or a co-crosslinking agent together. The crosslinking aid or co-crosslinking agent is basically effective as long as it has a reaction activity with respect to peroxy radicals and polymer radicals, and the kind thereof is not particularly limited. The preferred one is
Triallyl cyanurate, triallyl isocyanurate
G, triacrylformal, triallyl trimellitate
, N, N'-m-phenylene bismaleimide, dipropargyl terephthalate, diallyl phthalate, tetraallyl terephthalamide, triallyl phosphate and the like. The amount used is preferably 0.1 to 10 parts by weight, more preferably 0.5, based on 100 parts by weight of the copolymer.
˜5 parts by weight. In addition, the copolymer containing vinylidene fluoride can be vulcanized by polyamine vulcanization, polyol vulcanization, polythiol vulcanization, etc. which are conventionally used in vulcanization of fluororubber.
Further, as a blend-co-crosslinkable substance, silicone oil, silicone rubber, ethylene / vinyl acetate copolymer, 1,2-polybutadiene, fluorosilicone oil, fluorosilicone rubber, fluorophosphacene rubber, hexafluoropropylene / Ethylene copolymers, tetrafluoroethylene / propylene copolymers, and also other radically reactive polymers are used. The amount of these used is not particularly limited, but should not be so large as to essentially impair the properties of the copolymer of the present invention.

Further, a pigment for coloring the copolymer,
Fillers, reinforcing agents, etc. are used. As inorganic fillers, carbon black, TiO ₂ , SiO ₂ , clay, talc, etc. are commonly used as fillers and reinforcing agents, and polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrilide, etc. are used as organic substances. Such as fluoroethylene, tetrafluoroethylene / ethylene copolymer, tetrafluoroethylene / vinylidene fluoride copolymer, vinylidene fluoride / hexafluoropropylene copolymer, tetrafluoroethylene / vinylidene fluoride / hexafluoropropylene copolymer Examples thereof include a fluorinated copolymer.

As a means for mixing these hardening components, an appropriate method is adopted depending on the viscoelasticity and form of the material, and in the case of a solid state, an ordinary open roll or powder mixer is used. In the case of a liquid, a usual mixer is used as appropriate. Of course, it is also possible to dissolve or disperse the solid components in a solvent and disperse and mix them.

The vulcanization temperature and time depend on the kind of the peroxide used, but in the case of press vulcanization, it is usually 120.
The oven vulcanization is conducted at a temperature of 150 to 250 ° C. for 5 to 30 minutes, and the oven vulcanization is conducted at a temperature of 150 to 250 ° C. for 1 to 24 hours. In addition,
In vulcanizing the fluorine-containing copolymer of the present invention, the degree of vulcanization can be increased by heating the fluorine-containing copolymer in air at a temperature of 150 to 250 ° C in advance.

The fluorine-containing copolymer of the present invention utilizes ordinary heat resistance, oil resistance, and solvent resistance, for example, oil seals for automobiles, fuel hoses, O-rings,
It is also useful as a gasket seal.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to Examples and Test Examples.

Example 1 A fluoroalkyl vinyl ether: CH ₂ = CHOCH was placed in a stainless steel autoclave having an internal volume of 200 ml.
₂ (CF ₂ ) ₂ H32.7 g and R-113 40 ml were charged and cooled with dry ice / acetone, and then R-1, 2,4,5-trichloroperfluorohexanoyl peroxide.
1.5 ml of 13 solution (concentration 0.3 g / ml) was charged and the system was replaced with nitrogen. Next, tetrafluoroethylene 6
Charge 1.4g and 7.2g ethylene, shake at 20 ℃,
The reaction was performed for 1 hour. Along with the reaction, the gauge pressure in the system is 21.
It fell from 4 kg / cm ² to 20.8 kg / cm ² . Unreacted monomer was discharged, the solvent and the monomer were removed by heating and reduced pressure to obtain 11.8 g of an amorphous copolymer. The composition of this copolymer was ethylene / tetrafluoroethylene / fluoroalkyl vinyl ether = 36: 40: 24 (molar ratio), and Tg was −19 ° C.

Examples 2 to 14 Copolymers were obtained by repeating the procedure of Example 1 except that the charged amount shown in Table 1 was used. The composition and properties of the copolymer are shown in Table 1.

[0031]

[Table 1]

Example 15 A stainless steel autoclave having an internal volume of 3000 ml was charged with 1000 ml of ion-exchanged water, 2 g of ammonium perfluorooctanoate, 1.0 g of sodium sulfite and 5 g of disodium hydrogen phosphate dodecahydrate. After closing the lid of the autoclave and performing nitrogen replacement 3 times, the inside of the autoclave was evacuated. Fluoroalkyl vinyl ether: CH ₂
= 300 g of CHOCH ₂ CF ₂ CF ₂ H was inhaled into the system, and then, at 15 ° C. with stirring, with a tetrafluoroethylene / ethylene mixed gas so that the molar ratio of the internal space was tetrafluoroethylene / ethylene = 47/53. 21 kg / cm ²
The pressure was raised to G.

A 10% by weight aqueous solution of ammonium persulfate was added to 5 parts.
Polymerization was initiated by press-fitting. Although the pressure drop starts immediately, when the pressure drops to 20 kg / cm ² , the pressure is restored to 21 kg / cm ² with a tetrafluoroethylene / ethylene (molar ratio 46/54) mixed gas, and then the reaction is continued while repeating such pressure reduction and pressure restoration. Was continued for 5.4 hours. The polymerization reaction was stopped by releasing gas and quenching.

After recovering a white aqueous dispersion having a solid content of 24.0% by weight, this was coagulated with potassium alum, washed with water and dried to obtain a white polymer. The polymer composition was found to be tetrafluoroethylene / ethylene / fluorovinyl ether = 40/22/38 (molar ratio) from ¹⁹ F-NMR and ¹ H-NMR. Intrinsic viscosity [η]
Was 0.83 and Tg was + 7.5 ° C.

Test Example 1 The polymer vulcanization molded sheet of Example 15 was subjected to a dip test to examine the amine resistance and oil resistance. 100 parts by weight of polymer, 20 parts by weight of MT carbon, 10 parts by weight of calcium hydroxide (CML2000), 5 parts by weight of triallyl isocyanurate and 4 parts by weight of t-butylperoxybenzoate were blended, and at 150 ° C. and 35 kgf / cm ² . 10
After press vulcanization for 1 minute and oven vulcanization at 160 ° C. for 4 hours to prepare a vulcanized molded sheet, amine resistance and oil resistance were measured. As a comparison, Daiel G-9
02 100 parts by weight, 20 parts by weight of MT carbon, 4 parts by weight of triallyl isocyanurate and 1.5 parts by weight of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane are mixed at 160 ° C. Amine resistance and oil resistance of the molded sheet prepared by press vulcanization at 35 kgf / cm ² for 10 minutes and oven vulcanization at 180 ° C. for 4 hours were also measured. The results are shown in Table 2.

[0036]

[Table 2] Table 2 Amine resistance and oil resistance test Example 15 Daier G-902 Chemicals (immersion condition) Volume change Appearance Volume change Appearance Ethylene diami 13.0% No change 6.0% Crack generation (30 ° C x 30 minutes) DBU Note ) 11.0% No change 2.6% Cracking (30 ° C x 2 hours) ASTM No3 oil 11.8% − 9.9% − (175 ° C x 95 hours) Note) DBU = 1,8-diaza-bicyclo [5,4,0]
Undecen-7

Examples 16 to 19 Copolymers were obtained by repeating the procedure of Example 15 except that the conditions shown in Table 3 were used. The composition and properties of the copolymer are shown in Table 3.

[0038]

[Table 3]

Example 20 In a stainless steel autoclave having an internal volume of 3000 ml, 1000 ml of ion-exchanged water, 2 g of ammonium perfluorooctanoate, 1.0 g of sodium sulfite, 5.0 g of disodium hydrogen phosphate 12-hydrate, fluoroalkyl vinyl ether: CH ₂ = 40 g of CHOCH ₂ (CF ₂ ) ₄ H was charged. After closing the lid of the autoclave and performing nitrogen replacement 3 times, the mixture was stirred at 30 ° C., and the internal space molar ratio was tetrafluoroethylene / ethylene = 31/69. /cm
It was increased to ² G. Polymerization was initiated by pressing in 15 g of a 10 wt% aqueous solution of ammonium persulfate. Immediately after the pressure drop started, when 20 kg / cm ² was reached, 20 g of vinyl ether was injected under pressure with a mixed gas of tetrafluoroethylene / ethylene (molar ratio 74/26) to obtain 21 kg / cm ² G at the same time.
Boosted to. Thereafter, the reaction was continued for 6.6 hours by adding a monomer at each pressure drop. Polymerization was stopped by outgassing and quenching. After recovering a white aqueous dispersion having a solid content of 16.1%, this was coagulated with potassium alum, washed with water and dried to obtain a white polymer. The polymer composition is ¹⁹ F-NMR and ¹ H-NMR.
Therefore, it was tetrafluoroethylene / ethylene / fluorovinyl ether = 40/25/35 (molar ratio).
The intrinsic viscosity [η] was 0.37 and Tg was -13.3 ° C.

Examples 21 to 23 Copolymers were obtained by repeating the procedure of Example 20 except that the conditions shown in Table 4 were used. The composition and properties of the copolymer are shown in Table 4.

[Table 4]

Test Example 2 The polymer vulcanization molded sheet of Example 22 was subjected to a dip test to examine the amine resistance and oil resistance. 100 parts by weight of polymer, 30 parts by weight of magnesium oxide (MA-30), 4 parts by weight of triallyl isocyanurate, and 3.5 parts by weight of benzoyl peroxide were added, and the mixture was added at 120 ° C.
Press vulcanize for 50 minutes at 120 ° C, 35kgf / cm ² for 4
After forming a vulcanized molded sheet by vulcanizing in an oven for an hour, amine resistance and oil resistance were measured. For comparison, 100 parts by weight of Daier G-902, 20 parts by weight of MT carbon, 4 parts by weight of triallyl isocyanurate and 1.5 parts by weight of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane were used. Blended, 160 ℃, 35kg
The amine resistance and oil resistance were also measured for the molded sheet prepared by press vulcanization at f / cm ² for 10 minutes and oven vulcanization at 180 ° C. for 4 hours. The results are shown in Table 5.

[0042]

[Table 5] Table 5 Amine resistance and oil resistance Example 22 DAI-EL G-902 Chemicals (immersion conditions) Volume change Appearance Volume change Appearance Ethylenediami 1.9% No change 6.0% Crack generation (30 ° C x 30 minutes) DBU Note) 1.9% No change 2.6% Cracking (30 ° C x 2 hours) ASTM No3 Oil 4.4% -1.1 %- (175 ° C x 70 hours) Note) DBU = 1,8-diaza-bicyclo [5,4,0]
Undecen-7

Claims (3)

(57) [Claims] 1. Tetrafluoroethylene 10 to 50 mol%, formula: CH ₂ ═CHOCH ₂ (CF ₂ ) nX (I) [wherein, X represents halogen or hydrogen, and n represents a number of 2 to 8. ] The amorphous fluorine-containing copolymer which consists of 15-60 mol% of fluoro vinyl ether and 10-50 mol% of ethylene, and whose number average molecular weight is 1,000-1,000,000. 2. A composition comprising (a) 100 parts by weight of the amorphous fluorocopolymer according to claim 1, and (b) 0.05 to 10 parts by weight of an organic peroxide compound. 3. The composition according to claim 2, further comprising 0.1 to 10 parts by weight of (c) a crosslinking aid or a co-crosslinking agent.