JPH04255716A - Production of perfluorinated copolymer - Google Patents

Abstract

PURPOSE:To easily polymerize a fluorine-containing amorphous polymer having arbitrary glass-transition temperature and refractive index. CONSTITUTION:The objective polymer is produced by the radical copolymerization of perfluoro(allyl vinyl ether) or perfluoro(butenyl vinyl ether) with perfluoro-2,2-dimethyl-1,3-dioxole.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a perfluorocopolymer having a cyclic structure in its main chain.

0002

[Prior Art] Regarding fluorine-containing polymers having a cyclic structure in the main chain, especially perfluorocyclic polymers, Japanese Patent Application Laid-Open No.
13125, CF2=CFO(CF2)nCF=CF2 undergoes cyclopolymerization alone, and the general formula

0003

[Chemical formula 1]

It has been shown that an amorphous, solvent-soluble polymer having a cyclic structure of Usually, the softening point temperature of an amorphous polymer is determined by the glass transition temperature Tg.
Before and after this, many physical properties such as mechanical properties and electrical properties change significantly. CF2=CFO(CF2)nCF
The cyclic polymer obtained by homopolymerizing =CF2 is no exception, and the polymer with n=1 has Tg=69°C and n=2.
Even in this case, since Tg = 108°C, the heat distortion temperature was not very high, and there was a problem that it was insufficient for use at high temperatures.

On the other hand, regarding perfluorocyclic polymers, U
SP4,754,009 contains perfluoro-2,2-dimethyl-1,3-dioxole (hereinafter P
An amorphous polymer is obtained by copolymerizing DD) and tetrafluoroethylene, and this copolymer is soluble in solvents, has excellent light transmittance, and has a very high Tg. It has been shown that

[0006]

[Case 2]

However, as the tetrafluoroethylene content increases, the Tg of such copolymers decreases significantly;
Furthermore, since crystallinity appears, there are problems in that transparency decreases and solvent solubility is impaired. Moreover, since this copolymer is obtained by the reaction of a gaseous monomer and a liquid monomer, it is difficult to control the composition, and it is difficult to obtain a copolymer having the desired Tg. There is a problem that a homopolymer tends to be produced as a by-product.

[0008]

Problems to be Solved by the Invention The present invention solves the above-mentioned drawbacks of perfluoropolymers, and provides perfluoropolymers that have an appropriate glass transition temperature that can withstand high-temperature use while maintaining solvent solubility and transparency. The purpose is to provide a new polymer.

[0009]

[Means for Solving the Problems] Based on the recognition of the above-mentioned problems, the present inventors have conducted intensive studies on perfluoromonomers having a cyclic structure that can be copolymerized with cyclization polymerizable perfluoromonomers. As a result of repeated experiments, we discovered that a specific combination of monomers can be radically copolymerized at any ratio without losing cyclization polymerizability. Furthermore, a perfluoropolymer can be obtained in which the copolymer has no crystallinity over the entire composition range, maintains solvent solubility and transparency, and has a glass transition temperature over a wide range of 70 to 300°C. was newly discovered. Furthermore, it was surprisingly newly discovered that the copolymer of the present invention is not only transparent but also has a very low refractive index, and that the refractive index can be controlled arbitrarily by changing the copolymer composition.

The present invention has thus been completed based on the above findings, and consists of a perfluoromonomer having one carbon-carbon double bond of different polymerizability at each end of the molecule and perfluoro-2,2 The present invention provides a novel method for producing a perfluorocopolymer, which is characterized by radical copolymerization with -dimethyl-1,3-dioxole.

In the present invention, radical polymerization is used as the polymerization method. That is, the polymerization method is not limited in any way as long as it proceeds in a radical manner, and examples thereof include polymerization using an organic or inorganic radical initiator, light, ionizing radiation, or heat. As for the polymerization method, bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be used.

In the present invention, the perfluoromonomer having one carbon-carbon double bond with different polymerizability at each molecular end includes a vinyl ether group, an allyl group, an allyl ether group, an isopropenyl group, and an isopropenyl ether group. Among the carbon-carbon double bonds such as group, butenyl group, butenyl ether group, acryloyl group, methacryloyl group, each has one group with different polymerizability at the end of the molecule, and all of the hydrogens bonded to carbon are Compounds substituted with fluorine are employed. Since such perfluoromonomers have carbon-carbon double bonds with different polymerizability, they undergo cyclization polymerization during radical polymerization, resulting in a polymer having a ring structure in the main chain.

[0013] Furthermore, perfluorovinyl ether monomers are preferably employed as monomers that are likely to undergo cyclization polymerization. Further, it is not preferable that the molecular length is too long or too short because the cyclization polymerizability decreases. Preferably, the number of atoms connecting carbon-carbon double bonds is 2 to 4 (although the atomic chain connecting carbon-carbon double bonds may have a ring structure or a branched structure). , the number of atoms shown here is the number of atoms that connect carbon-carbon double bonds at the shortest distance).

Among them, the formula CF2=CFO(CF2)nC
A perfluorovinyl ether compound represented by F=CF2 (n is 1 or 2) is most preferably employed from the viewpoint of cyclization polymerizability and polymerizability with PDD.

Monofunctional perfluorovinyl ether monomers such as perfluoropropyl vinyl ether or monomers such as hexafluoropropylene are difficult to copolymerize with other monomers such as tetrafluoroethylene. , a copolymer containing 20% or more of these monomers cannot be obtained. Copolymerization with PDD is similarly difficult. However, it is possible to copolymerize the above-mentioned perfluorovinyl ether and PDD in any ratio and to obtain a copolymer having any composition at a high yield by changing the charging composition. In addition, in all compositions, the perfluorovinyl ether undergoes cyclopolymerization and copolymerization with PDD, so an amorphous and transparent polymer is obtained, and unreacted double bonds that would form a crosslinked structure are eliminated. It is soluble in solvents because it does not remain in the polymer.

The Tg of perfluorovinyl ether/PDD copolymers increases as the PDD content increases. Depending on the copolymerization composition, polymers having a wide range of Tg from 70°C to 300°C can be obtained, but if the PDD content exceeds 95%, the solubility in solvents will be slightly poor, making it impractical.

The copolymer of the present invention is not only transparent but also has a low refractive index, and by changing the copolymer composition, 1.
29 to 1. It is possible to obtain polymers with a refractive index between 34.

The perfluoro copolymer described above can be used in combination with other copolymer components to form a ternary or multicomponent copolymer to the extent that the essence of these components is not impaired, and if necessary, it can be prepared by some method. The polymer may be crosslinked with.

Other monomers to be copolymerized include:
The monomer having radical polymerizability is not particularly limited, and a wide range of examples include fluorine-containing monomers, hydrocarbon monomers, and others. Of course, these other monomers may be used alone in radical copolymerization with the specific perfluorovinyl ether monomer and perfluorodioxole, or two or more of these monomers may be used in combination. The above copolymerization reaction may also be carried out.

In the present invention, it is usually desirable to select a fluorine-containing monomer such as a fluoroolefin or fluorovinyl ether as the other monomer. for example,
Preferred examples include tetrafluoroethylene, perfluoromethyl vinyl ether, perfluoropropyl vinyl ether, or perfluorovinyl ether containing functional groups such as carboxylic or sulfonic acid groups; vinylidene fluoride, vinyl fluoride, chloro Trifluoroethylene and the like are also exemplified. The content of these other monomers is preferably at a level that does not impair the essence of the perfluorocopolymer, and is preferably at most 50% by weight, more preferably at most 20% by weight.

[0021] In the present invention, as the method for crosslinking the perfluoropolymer, commonly used methods can be appropriately used. For example, crosslinking can be achieved by copolymerizing a monomer having a crosslinking site, by adding a crosslinking agent, or by using radiation or the like.

[0022]

[Operation] In the present invention, a specific perfluoromonomer and PDD are copolymerized in any ratio, and since the composition ratio of these monomers in the copolymer can be freely controlled, various objective physical properties can be achieved. A perfluoro copolymer with In addition, the perfluoro copolymer obtained by the present invention has substantially no crystallinity over the entire composition range, exhibits high transparency and high light transmittance despite being a fluororesin, Furthermore, since it is a perfluoropolymer, it is thought to have a lower refractive index than ordinary hydrocarbon resins, and is also superior in moisture resistance, weather resistance, and chemical resistance. However, it goes without saying that such explanations are provided to assist in understanding the present invention and are not intended to limit the present invention.

[0023]

[Example] Example 1 10g of perfluorobutenyl vinyl ether, PD
D's 0. 5g, trichlorotrifluoroethane 10
g and diisopropyl peroxydicarbonate as a polymerization initiator. 02g was placed in a pressure-resistant glass ampoule with an internal volume of 50ml. After the system was frozen and degassed three times, it was shaken in a water bath at 40°C for 22 hours. As a result, the polymer was 7. I got 1g.

[0024] When this polymer was dissolved in perfluorobenzene and the 19F-NMR spectrum was measured, in addition to the absorption spectrum derived from the polymerized unit of perfluorobutenyl vinyl ether, absorption of the CF3 group derived from PDD was confirmed. It was done. In addition, when measuring the IR spectrum, no absorption of double bonds derived from perfluorobutenyl vinyl ether was observed, and it is soluble in solvents.
It is thought that perfluorobutenyl vinyl ether is copolymerized with PDD while undergoing cyclization polymerization.

This polymer is called "Florinat" FC-75.
(Product name: Liquid whose main component is perfluoro(2-butyltetrahydrofuran) manufactured by 3M Company, hereafter FC-7
5) to make a 10% solution. After casting this on a glass plate, it was heated at 30°C for 5 hours and then at 50°C.
It was left standing for 20 hours. Furthermore, when the refractive index of the film obtained by vacuum drying at 100°C was measured using an Abbe refractometer, it was found to be 1. It was 33. When this film was placed in water, the interface between the film and water could not be visually confirmed. Moreover, when the light transmittance of this film was measured, it was 95% at a wavelength of 250 to 700 nm.

Example 2 8 g of perfluorobutenyl vinyl ether, PDD
2 g of FC-75, 10 g of FC-75 and 0.0 g of diisopropyl peroxydicarbonate as a polymerization initiator. 02g
was placed in a pressure-resistant glass ampoule with an internal volume of 50 ml. After the system was frozen and degassed three times, it was shaken in a water bath at 40°C for 20 hours. As a result, 6. I got 7g. The glass transition point of this polymer is 157°C, and the intrinsic viscosity [
η] is 0.0 at 30°C in FC-75. 35, it was a tough and transparent glassy polymer. IR spectrum 193
The PDD content was determined from the absorbance at 0 cm-1 and was 12%. In addition, when the refractive index was measured using an Abbe refractometer, 1. It was 32.

Example 3 5 g of perfluorobutenyl vinyl ether, PDD
and 0.5 g of diisopropyl peroxydicarbonate as a polymerization initiator. 02g was placed in a pressure-resistant glass ampoule with an internal volume of 50ml. After the system was frozen and degassed three times, it was shaken in a water bath at 40°C for 1 hour. As a result, 3. I got 8g. The glass transition point of this polymer is 213°C, and the intrinsic viscosity [η] is 30 in FC-75.
0 at °C. 99, it was a tough, transparent glassy polymer. The PDD content was determined from the absorbance at 1930 cm −1 of the IR spectrum and was found to be 71%. Also,
When the refractive index was measured using an Abbe refractometer, 1. 3
It was 0.

Example 4 2 g of perfluoroallyl vinyl ether, 8 g of PDD, 10 g of trichlorotrifluoroethane, and 0.0 g of diisopropyl peroxydicarbonate as a polymerization initiator. 02g was placed in a pressure-resistant glass ampoule with an internal volume of 50ml. After the system was frozen and degassed three times, it was shaken in a water bath at 30°C for 20 hours. As a result, the polymer was 7. g
Obtained. The glass transition point of this polymer is 210°C,
Intrinsic viscosity [η] is 1. FC-75 at 30°C. It was 15. The PDD content was determined from the absorbance at 1930 cm −1 of the IR spectrum and was found to be 82%. When the refractive index was measured using an Abbe refractometer, 1. It was 29.

4 g of comparative example PDD, 65 g of trichlorotrifluoroethane
and 0.0% of diisopropyl peroxydicarbonate as a polymerization initiator. 05g was placed in a stainless steel ampoule with an internal volume of 100ml. After freezing and degassing the system three times, 10 g of tetrafluoroethylene was added. After shaking in a water bath at 55°C for 5 hours, the polymer was 10. 5
g got it. According to the F content analysis, the PDD content was about 10%. This polymer was press-molded at 340° C. to make a film, but it was translucent with opaque parts in the form of white spots mixed therein. Furthermore, this polymer had a portion that was soluble in FC-75 and a portion that was difficult to dissolve in FC-75.

[0030]

[Effect of the invention] The present invention allows perfluorovinyl ether and perfluorodioxole, which have cyclization polymerizability, to be copolymerized in any ratio, and the composition ratio of these monomers in the copolymer can be freely adjusted. Since it can be controlled, it has the effect that perfluoro copolymers with various desired physical properties can be obtained. In addition, the perfluoropolymer obtained by the present invention can control the glass transition temperature while maintaining amorphous property by arbitrarily selecting the copolymer composition, has a high glass transition temperature, and has excellent solvent solubility and It has the effects of excellent transparency and high heat resistance. It also has the effect that a polymer having a low refractive index and having an arbitrary refractive index can be obtained depending on the copolymer composition.

The perfluoropolymer according to the present invention is an amorphous, transparent, and solvent-soluble polymer that has excellent properties as a perfluoropolymer, such as heat resistance and chemical stability. Due to these characteristics, it has been recognized that it is possible to make ultra-thin films without defects such as pinholes, and it can also be applied to coating materials, separation membrane materials, etc. By taking advantage of its low refractive index, it can also be applied to optical materials such as antireflection agents and optical fiber cladding materials. Furthermore, since the fluorine-containing polymer according to the present invention is a fluorine compound, it has a low dielectric constant, so it can be applied as an electronic material.

Further, the perfluoropolymer according to the present invention can be used in electric wire coating materials, magnetic recording medium protective layers, gas selective permeation film materials, optical lenses, optical waveguides, artificial crystalline lenses,
Low-reflection processing agents, laminated materials for safety glass, optical element adhesives,
Solar cell light intake surface material, color filter protective film, flux creep-up prevention agent, mold release agent, semiconductor protective layer, aircraft window material, mirror surface coating material, mirror base material, fishing line, semiconductor carrier, pellicle protective film materials, electrophotographic photoreceptor surface layers, nonlinear optical elements, photochromic molded body substrates, filter media, electrophoresis supports, photoreactors, bioreactors, ultraviolet lamps, and the like.

Claims (3)

[Claims] [Claim 1] Radical copolymerization of a perfluoromonomer having one carbon-carbon double bond with different polymerizability at the end of the molecule and perfluoro-2,2-dimethyl-1,3-dioxole. A method for producing a perfluorocopolymer characterized by: Claim 2: A claim in which the copolymerization is carried out in such a range that the content of perfluoromonomer is 1 to 99% by weight, and the content of perfluoro-2,2-dimethyl-1,3-dioxole is 1 to 99% by weight. 1. Method for producing perfluoro copolymer. Claim 3: The perfluoromonomer has the general formula CF2=C
FO(CF2)nCF=CF2 (where n is 1 or 2
It is. ) The method for producing a perfluorocopolymer according to claim 1, which is a perfluorovinyl ether represented by: