JPS59147006A - Production method of tetrafluoroethylene/ethylene copolymer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a tetrafluoroethylene/ethylene copolymer, and more particularly to a method for producing a tetrafluoroethylene/ethylene/2-trifluoromethylpropylene copolymer with improved high-temperature crack resistance. Concerning the manufacturing method.

Tetrafluoroethylene (hereinafter referred to as TFE)/ethylene copolymer has excellent chemical resistance, electrical properties, mechanical properties, etc., and can be molded by injection molding and extrusion molding like general thermoplastic resins. For this reason, it is attracting attention as a new fluororesin.

However, TFE/ethylene copolymers have the disadvantage of being susceptible to cracking at high temperatures. In order to improve the disadvantages of linoleum, it has been proposed to copolymerize various third monomers as modifiers.

For example, Japanese Patent Publication No. 39-12109 describes that copolymerization using inbutylene as a modifier can further lower the molding temperature and provide a copolymer that does not change color at high temperatures. .

However, in this case, the tendency of the copolymer to crack at high temperatures is not mentioned in this publication, but in reality it has hardly been improved.

In addition, Japanese Patent Publication No. 47-23671 describes vinyl monomers having a side chain containing at least two carbon atoms, Tatoeha R-CF=CF2, RO-CF:C as the third component.
F2 or CH2=CX-CH2-R7 (where K
is a C2-C8 hydrocarbon group, and X is hydrogen or methyl. It is described that the mechanical properties of a TFE/ethylene copolymer at high temperatures are improved by copolymerizing a vinyl monomer represented by the following. However, among the above vinyl monomers, R-CF:CF2 and RO-CF
The monomer represented by =CF2 has poor polymerizability, is expensive and difficult to obtain, and is therefore economically disadvantageous.

When a monomer represented by 0H2=cx-OH2R is used, there is a drawback that the resulting copolymer has poor heat resistance.

The present inventors conducted intensive research to improve the above-mentioned drawbacks observed in the prior art, and found that by copolymerizing 2-trifluoromethylpropylene as a third component to a TFE/ethylene copolymer, It was discovered that crack resistance at high temperatures can be advantageously improved, and that the third component has good polymerizability, leading to the completion of the present invention.

That is, the gist of the present invention is that TFE, ethylene and 2
2-trifluoromethylpropylene used in the present invention is a known compound, and can be prepared, for example, according to the following reaction formula. The polymerization is carried out in suspension polymerization in an aqueous medium using a fluoroalkane as a solvent and in the presence of an organic peroxide as a radical polymerization initiator. However, solution polymerization and emulsion polymerization can also be employed in accordance with the manufacturing method of TFE/ethylene copolymer.

The radical polymerization initiator used in the production method of the present invention is preferably an organic peroxide, and suitable organic peroxides include the formula: , n is an integer of 2 to 8).
(Refer to Publication No.-24072).

Specifically, they include di-perfluoropropionyl peroxide, di(ω-hydroperfluorohexanoyl) peroxide, and di(ω-chloroperfluoropropionyl'y''-oxide).

In addition, the general formula: [CJ(C;F2CFCg)mC,F
2C00) (Here, m is an integer from 1 to 10.

), such as di(trichlorobarfurolohexanoyl) peroxide, and low-temperature decomposition type peroxides, such as diisobutyryl peroxide and diisopropyl peroxycarbonate, are preferably used.

Chlorofluoroalkanes as solvents include trichlorotrifluoroethane, dichlorotetrafluoroethane,
Included are chlorotrifluoromethane, dichlorodifluoromethane, chlorodifluoromethane, and the like. The amount of the solvent used is preferably in the range of 10 to 100% by weight based on the aqueous medium.

The polymerization temperature is preferably in the range of 0 to 80°G, preferably as low as possible to avoid the formation of ethylene-ethylene chains.

The polymerization pressure is determined depending on the type, amount, vapor pressure, etc. of the solvent that dissolves the monomer, but is usually 0 to 50 to 9/a.
RG is preferably in the range of 1 to 15Kli'/c in industrial terms.
/G range is desirable.

Incidentally, the polymerization operation may be carried out in accordance with the conventional polymerization operation of TFE/ethylene copolymer.

In addition, in the production method of the present invention, common chain transfer agents such as n-pentane, n-hexane,
Impentane, carbon tetrachloride, etc. can also be used.

The copolymer obtained by the production method of the present invention is usually T F
It has a composition ranging from 40 to 60 mole percent E, 60 to 40 mole percent ethylene, and 0.1 to 20 mole percent 2-trifluoromethylpropylene. As the content of 2-trifluoromethylpropylene increases, the high-temperature crack resistance is further improved, but a range of heat resistance of 5 to 45 moles and 2-trifluoropropylene of 0.1 to 10 moles is preferred.

Next, examples and comparative examples will be shown to specifically explain the present invention. The high temperature crack resistance and flow value were measured as follows.

High temperature crack resistance A sheet piece of 38m x 13cm x 2rra thick was made with a notch and bent, heated from 80°G at a rate of 2°C/min,
Measure the temperature at which cracks occur.

Using a flow value increasing type flow tester, temperature 300°C 1 load 7
Under the conditions of K9/rd, the volume (-) flowing out per second from a nozzle with an inner diameter of 2 mm and a land length of 8 mm is measured.

Example 1 500 g of deoxygenated water in an autoclave with an internal volume of 1.5
+7+7! After replacing the mixture with nitrogen, 500 g of trichlorotrifluoroethane was added and the temperature was adjusted to 40'C. Next, a mixture of TFE/ethylene/2-trifluoromethylpropylene (molar ratio 80:19:05) was injected and the pressure was increased to 4.45 K9/cJ G. When 1.22 F of diimbutyryl peroxide was charged, a polymerization reaction occurred. The polymerization pressure was increased to TFE/ethylene/2-1-IJ.
Fluoromethylpropylene (molar ratio 51.6:46
．． 4:2.0) was kept constant by additional addition of the mixture. After polymerization was carried out for 170 minutes, unreacted monomers were released, and the produced white powder was washed with water and dried to obtain 68 grams of copolymer. Melting point 269°C0 flow value 1.6X10
-2mA'/sec・High temperature crank resistance 163°C0 Example 2 The amount of diisobutyryl peroxide charged was 1°027
The same procedure as in Example 1 was repeated except that 68 g of a copolymer was obtained. Melting point 268°co flow value 0.33
x 10-2. +v/sec. High temperature crack resistance 183°C
0 Example 3 The composition of the initially charged monomer mixture was set to a molar ratio of 80:19.
Copolymer 601 was obtained by repeating the same procedure as in Example 1, except that the polymerization pressure was adjusted to 5.45 to 7/CIIIG, and the composition of the additionally charged seven-mer mixture was changed to a molar ratio of 51:45:4. Ta. Melting point 257°c.

Flow value 1.4 x 1O-2v/sec. High temperature crack resistance 185°C0 Comparative example 1 500 m of deoxygenated water was placed in the same autoclave as in Example 1.
1 was added thereto, the atmosphere was replaced with nitrogen, dichlorotetrafluoroethylene 500F was added, and the temperature was adjusted to 200C. Then TFE/ethylene (molar ratio 80.3+19.7)
The mixture was pressurized to 4 to 9/clG. Ji (ω-
When 1 g of hydroperfluorohexanoyl peroxide and 14-pentane were charged, the polymerization reaction started. The polymerization pressure was adjusted to TjE/ethylene (molar ratio 53.5:4
6.5) It was kept constant by additional charging of the mixture. 18
After polymerization was carried out for 0 minutes, unreacted supernatant was released, and the produced white powder was washed with water and dried to obtain 64 grams of copolymer. Melting point 287°C070-value 0.61X10-2mZ/
seconds. High temperature crack resistance 135°C0 Comparative example 2 The initially charged seven-mer mixture was TFE/ethylene/isobutylene (molar ratio 80.6217.5:1.9), and the polymerization pressure was 6.8KS'/cJG. , the monomer mixture to be additionally charged is TFE/ethylene/isobutylene (
The molar ratio was 53.3:43.3+3.4), and the polymerization was 29
The same procedure as in Comparative Example 1 was repeated except that the test was carried out for 0 minutes to obtain 95 g of a white copolymer. Melting point: 259,600 Flow value: 0
．． 9 x 102 m 17 seconds. High temperature crack resistance 140
°C0 Patent Applicant Daikin Industries, Ltd. Representative Patent Attorney Aoyama Aoyama (2 others)

Claims (1)

[Scope of Claims] 1. A method for producing a tetrafluoroethylene-7-ethylene copolymer, which comprises copolymerizing tetrafluoroethylene, ethylene, and 2-trifluoromethylpropylene in the presence of a radical polymerization initiator. 2. The copolymer obtained has a composition of 40 to 60 moles of tetrafluoroethylene, 60 to 40 moles of ethylene, and 0.1 to 20 moles of 2-trifluoromethylpropylene. manufacturing method. 3 The composition of the resulting copolymer is 45 to 55 moles of tetrafluoroethylene, 55 to 45 moles of ethylene, and 2
-Trifluoromethylpropyl 1 fluoride 10 mol.