JPH0485312A - Production of fluorocopolymer - Google Patents

Abstract

PURPOSE:To obtain a vinylidene fluoride/hexafluoroacetone/ fluoroolefin copolymer at good efficiency without using trichlorofluoroethane by using a perfluoroether compound as a solvent for the polymerization. CONSTITUTION:A perifluoroether compound is used as a solvent for polymerization in producing a vinylidene fluoride/hexafluoroacetone/fluoroolefin copolymer. This perfluoroether is an ether in which all of the hydrogen atoms in the molecule are replaced by fluorine atoms, and cyclic perfluoro ethers, even though the lengths of the side chains are different, are desirable as the polymerization solvent.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to coating materials that can be applied to the surfaces of various plastic materials to impart various physical properties, such as coating materials for optical fibers made of plastic core materials such as polymethyl methacrylate. The present invention relates to a method for producing a thread polymer (having excellent properties as a sheath material, etc.), and more specifically relates to a method for producing a vinylidene fluoride-hexafluoroacetone-fluoroolefin copolymer.

[Prior art] Conventionally, in the production of this type of copolymer, it has been common to use a radical copolymerization method as a polymerization reaction, and usually an oil-soluble radical initiator is used in an organic solvent to
The reaction is carried out at a temperature in the range of -130<0>C. Examples of the organic solvent include saturated hydrocarbons such as n-hexane and rhohebutane, fluorine-based solvents such as dichlorotetrafluoroethane and trichlorotrifluoroethane, and ester-based and ketone-based solvents. In particular, trichlorotrifluoroethane is the most advantageous in terms of its solubility, flammability, etc., and in practice, trichlorotrifluoroethane is used in polymerization.

This trichlorotrifluoroethane has been developed in recent years.

Due to its stability, its use is restricted as it causes destruction of the ozone layer.

Therefore, the use of a solvent instead of trichlorotrifluoroethane is being considered in various applications using this trichlorotrifluoroethane, and even in this type of polymerization reaction, a non-polluting solvent can be used instead of trichlorotrifluoroethane. Although a polymerization method using the above is desired, it is not sufficient in terms of solubility and the reaction yield is not satisfactory.

“Specific means for solving the problem] The present inventors
In view of these problems, the present invention has been arrived at as a result of intensive studies. That is, the present invention provides a method for producing a polycarbonate copolymer, which is characterized in that a perfluoroether compound is used as Jia in the polymerization reaction of a vinylidene fluoride-hexafluoroacetone-fluoroolefin copolymer. be.

In the present invention, either trifluoroethylene or tetrafluoroethylene can be used as the fluorinated olefin, and it is of course possible to use both of them to form a quaternary copolymer.

In the present invention, the component ratio of vinylidene fluoride, hexafluoroacetone, and fluoroolefin is not particularly limited, and it is possible to produce copolymers with various compositions, but as the content of each component increases, the resulting copolymer The coalescence generally exhibits the following physical properties: As the content of hexafluoroacetone increases, it becomes too soft and the hardness decreases. Furthermore, as the content of tetrafluoroethylene increases, melt moldability deteriorates. Also, as the content of trifluoroethylene increases, transparency decreases. As the content of vinylidene fluoride increases, transparency decreases.

Therefore, the composition may be determined in accordance with the desired physical properties after taking these characteristics into consideration.

For example, considering transparency, heat resistance, etc., generally,
Vinylidene fluoride is 30 to 85 mol%, hexafluoroacetone is 1 to 35 mol%, and fluoroolefin is 5 to 85 mol%.
In the present invention, a perfluoroether compound is preferably used as a polymerization solvent in a range of 50 mol%. It is generally commercially available under the trade name Fluorinert.

Among these, Fluorinert FC-72 (boiling point 56℃) and Fluorinert FC75I (boiling point 102℃) are the most excellent as polymerization solvents, and these are both perfluorinated cyclic ethers with different side chain lengths. It is.

Although the polymerization reaction is carried out using such a solvent,
Although the reaction mode is not particularly limited, a general polymerization method will be explained below.

A polymerization solvent is charged into an autoclave, and while stirring, the autoclave is purged with an inert gas such as nitrogen, and then aerated, a predetermined amount of raw material monomer is charged, and as a polymerization initiator, heptafluorobutyric peroxide, di-n-propyl peroxycarbonate, etc. is injected as a solution dissolved in a polymerization solvent.

These polymerization initiators may be appropriately selected and used depending on the reaction conditions, particularly the reaction temperature, etc., and the amount used is preferably in the range of 0.5 to 2% by weight based on the raw material monomer.

If the amount is less than this range, the polymerization reaction will not proceed sufficiently, and if it exceeds this range, there will be no special effect commensurate with the amount added, which is not economical.

The reaction temperature is usually selected from the range of 10 to 100°C.
．． If the degree of change is too low, the reaction rate is too slow and inefficient,
If the pressure is too high, the pressure may become high depending on the composition of the raw material, which may be dangerous, so these should be taken into consideration when determining the pressure. It is usually sufficient for the reaction to last about 30 hours, and after the completion of the reaction, it is preferable to purge the residual gas and then stabilize the remaining hexafluoroacetone as hemiacetal with methanol or the like. Thereafter, a polymerization product is obtained by conventional means.

In the polymerization reaction of the present invention, the solubility of the polymerization product in perfluoroether, which is a polymerization solvent, is appropriate, so that the reaction yield is 1 and the stability of the polymerization product is excellent. Moreover, since the boiling point of the polymerization solvent is comparatively high, the range of selection of reaction temperature conditions and polymerization initiator is widened, and it also prevents the recovery of the solvent after the reaction and the escape of the solvent in the reaction system. .

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 An autoclave having an internal volume of 11 was charged with 5301 liters of cyclic perfluoroether Fluorinate FC-72 manufactured by 3M Company, and while stirring, the inside of the autoclave was purged with nitrogen and then degassed. After repeating this operation three times, 270 g of hexafluoroacetone and 8 g of trifluoroethylene were added.
8g of vinylidene fluoride and 521g of vinylidene fluoride were charged, and the temperature of the inner hot water in the autoclave was adjusted to 26°C. Next, heptafluorobutyric peroxide (H
FBP) was added as 5% by weight of Fluorinert FC-72 and 15g as a liquid, and the reaction temperature was kept at 30 ± 1°C.
Stirring was continued for 8 hours. After the reaction was completed, residual gas was purged and residual hexafluoroacetone was stabilized as hemiacetal with methanol.

A slurry of the polymer was extracted from the autoclave, and solid-liquid separation was performed to obtain a polymer in the form of a cake.

This cake was washed with methanol, separated and dried to obtain 560 g of a copolymer. The yield was 637%.

Melt index (MI), thermal decomposition temperature (
Tm), crystallization temperature (Cp), and molecular weight were measured, and the results are shown in Table 1.

In addition, each physical property evaluation was performed as follows.

MI The dried resin is measured using an MI meter (TAKARA L20
36531).

Tm, Cp: The strand obtained with the MI meter was measured with DSC (Rigaku Denki TG-DSCCN8085E1).

Molecular weight Measured by gel permeation chromatography (CP8000, manufactured by Tosoh).

Number average molecular weight (polystyrene equivalent) A polymerization reaction was carried out in the same manner as in Examples 2 to 4, Comparative Examples 1 to 3, and Reference Example Example 1, using the composition of the raw material monomer and the polymerization solvent as shown in Table 1. Its physical properties were measured. The results are shown in Table 1.

As is clear from this table, when perfluoroether, which is the polymerization solvent of the present invention, is used, the yield is lower than when the polymerization reaction is performed using trichlorotrifluoroethane (reference example). The results are almost the same, and in other solvents, the reaction hardly progresses or the yield is extremely low, and there is a clear difference from the polymerization results of the present invention.51 Effects of the invention ] According to the method of the present invention, a fluorine-containing copolymer with excellent various physical properties can be efficiently produced without using trichlorotrifluoroethane, whose use is restricted due to ozone destruction, etc. Furthermore, since a wide selection range of reaction conditions, particularly reaction temperature, can be obtained, the reaction can be easily carried out by appropriately changing the reaction conditions depending on the desired physical properties.

Patent applicant: Central Glass Co., Ltd.

Claims (1)

[Claims] A method for producing a fluorine-containing copolymer, which comprises using a perfluoroether compound as a solvent in the polymerization reaction of a vinylidene fluoride-hexafluoroacetone-fluoroolefin copolymer.