JPS63260932A - Thin film of fluorinated polymer and formation of thin film - Google Patents

Abstract

PURPOSE:To make it possible to produce a nondefective thin film smoothly in an industrially advantageous manner, by using a fluorinated polymer having a ring structure in the main chain and forming a thin polymer film from a solution formed by dissolving this polymer in a solvent. CONSTITUTION:A fluorinated polymer having a ring structure in the main chain (e.g., a polymer having a ring structure of formula I, II or III) is dissolved in a solvent (e.g., perfluorobenzene or trichlorotrifluoroethane), and the solution is formed into a thin polymer film by a thin film formation process such as dipping or spin coating. In this way, a thin film of a thickness <=50mu can be produced smoothly in an industrially advantageous manner. Because a polymer having a perfluoro ring in the main chain is soluble in a solvent even when it is a homopolymer, it is soluble when it is a polymer or copolymer of a high fluorine content. The obtained thin film does not undergo decrease in the characteristics as a fluororesin, such as low refractive index, high heat resistance, low moisture permeability, high electrical resistance, high dielectric breakdown strength, etc. and is transparent because of its low crystallinity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film of a fluoropolymer, particularly a fluoropolymer having a ring structure in the -L chain, and a method for thinning the film.

[Prior Art] Conventionally, fluorine-containing polymers include polytetrafluoroethylene (PTFE) and perfluoroalkoxy vinyl ether/tetrafluoroethylene copolymer (PFΔ).
, tetrafluoroethylene/hexafluoropropylene copolymer (FEP), and polychlorotrifluoroethylene (PCTFE), but these fluoropolymers are generally insoluble in solvents, so it is difficult to make them into thin films. This is done by melt molding or a combination of melt molding and cutting.

[Problems to be solved by the invention] However, when making conventional fluorine-containing polymers into thin films, especially when trying to obtain a thin film of 50μ or less, defects such as pinholes or large defects occur. Molding pressure and stretching force are required, which is disadvantageous for industrial implementation. In particular, the above-mentioned difficulties are conspicuous with perfluoropolymers, and it has been difficult to smoothly and advantageously obtain a defect-free thin film with a thickness of 50 μm or less.

The object of the present invention is to improve the thickness of fluorine-containing polymers, especially perfluoropolymers, without impairing their properties.
The object of the present invention is to provide a defect-free thin film with a thickness of 0μ or less, and to provide a method for forming a fluoropolymer into a thin film that can be smoothly and advantageously carried out industrially.

[Means to Solve the Problem] As a result of various studies and examinations, the present inventor has found that by adopting a fluorine-containing polymer having a ring structure in the main chain, even in the case of a perfluoropolymer, It has been found that it is easy to form a thin film, and that a defect-free thin film of 50 μm or less can be produced smoothly and advantageously. Furthermore, by dissolving the specific fluorine-containing polymer in a fluorine-based solvent and using that solution, it is possible to create ultra-thin films with a thickness of 20μ or less, for example 0.02 to 5μ, which has never been possible before, without defects. It has been found that it is possible to form a film without the need for a film.

(Thus, the present invention was completed based on the above findings, and the fluorine-containing polymer having a ring structure in the main chain has a thickness of 5
The present invention provides a novel fluorine-containing polymer thin film characterized by being thinned to 0μ or less.

In the present invention, examples of the fluorine-containing polymer having a ring structure in the main chain include those having a ring structure represented by the general formula %. Among these,
Polymers having the following ring structures are typical. However, the content of the present invention is not limited to these only.

C.F.

CF3 CPCI There are two methods for producing these polymers. However, it is not limited to these manufacturing methods.

! , by cyclization polymerization (11CFa・CF-0-CF, -CF2-0-CF=
C.F.

CF, -CF, CF2-CF2 (US
P 3418303. GB 1106344 etc.) +
2) CF2=CF-CF2-CFCI-CF
, -CF=CF.

C.F.

C.F.C.I. (USP 3202643 etc.) +3) CF2=CF-0-CF2-CF=CF.

-CF2 2, those using cyclic monomers Cll5P 3978
030, etc.) The polymerization reaction is not particularly limited as long as it proceeds in a radical manner, but examples include polymerization using an organic radical initiator, light, ionizing radiation, or heat. The method is not particularly limited, and may include solution polymerization, which is carried out in an organic solvent in which so-called bulk polymerization monomers are dissolved, in which the polymer is directly subjected to polymerization, and solution polymerization carried out in an aqueous medium in the presence or absence of a suitable organic solvent. Examples include suspension polymerization carried out by adding an emulsifier to an aqueous medium, and emulsion polymerization carried out by adding an emulsifier to an aqueous medium.

Further, there is no problem in using copolymerized components to the extent that the essence of these components is not impaired. Other monomers to be copolymerized are not particularly limited as long as they are radically polymerizable monomers, and include a wide range of fluorine-containing monomers, hydrocarbon monomers, and others. Of course, these other monomers may be used alone in radical copolymerization with the above-described specific ring structure capable of introducing a specific ring structure into the main chain, or two or more of these monomers may be used in combination. The above-mentioned copolymerization reaction may be carried out in this manner. In the present invention,
Usually, it is desirable to select fluorine-containing monomers such as fluoroolefins and fluorovinyl ethers as other monomers. For example, tetrafluoroethylene, perfluorovinyl ether, etc. are preferable examples, and vinylidene fluoride, vinyl fluoride, chlorotrifluoroethylene, etc. may also be exemplified.

As for the copolymer composition, in order to take advantage of solubility, film-forming properties, and properties as a fluorine-containing polymer, the composition of the cyclic structure is preferably 20% or more, more preferably 40% or more. Such polymers are soluble in solvents, and the solvent used is not limited as long as it dissolves the above polymer, but perfluorobenzene, "Aflute" (trade name: fluorinated solvent manufactured by Asahi Glass Co., Ltd.) ), “Florinate” (trade name: liquid containing perfluoro(2-butyltetrahydrofuran) manufactured by 3M Company), Trique.

Lorotrifluoroethane and the like are preferred. As a matter of course, two or more appropriate types can be used in combination as a solvent. Particularly in the case of a mixed solvent, hydrocarbons, chlorinated hydrocarbons, fluorochlorinated hydrocarbons, alcohols, and other organic solvents can also be used in combination. Solution concentration is tl, olwt, %~5
0wt%, preferably Q, 1wt% to 2Qwt%.

The method for forming a thin film is not particularly limited as long as it is a method of forming a film from a solution using the above solution, such as a roll coater method, a casting method, a dipping method, a spin cord method, a water casting method, a Langmuir-Prodgett method, etc. .

The obtained thin film can be used while attached to a substrate or peeled off from the substrate. When used while attached to a substrate, the substrate can be of any shape and any material can be applied. Ru.

For example, magnetic disk substrates, optical fibers, electric wires, lens materials, separation membrane supports, hollow fibers, various tapes such as magnetic tapes, optical glass materials, electrodes, medical materials such as blood bags, various building materials, stainless steel, glass, aluminum, metals, etc. Furthermore, currently used fluororesin paints, PFA, ETFE, PTFE, PCTFE, PVdF
, a base material coated with a fluororesin such as FEP.

The thin film has no defects such as pinholes, is transparent, has a low refractive index, and has excellent heat resistance and mulberry resistance, so it can be used for various coating materials, electronic components, optical components, separation membranes, etc.

[Function] In the present invention, the reason why a fluorine-containing polymer having a ring structure in its main chain easily forms a thin film is that this polymer is soluble in a solvent, and various thin film forming methods such as dipping and spin cording can be used. This is because it is possible. Although the reason why this polymer is soluble in a special solvent is not clear, it is thought that the ring structures of the solvent and the polymer are similar and that the crystallinity of this polymer is low.

[Examples] Synthesis Example 1 30 g of perfluoroallyl vinyl ether, 30 g of trichlorotrifluoroethane, and 10 mg of polymerization initiator (C-F7CO) 2 were placed in a 50 cc pressure-resistant ampoule. After repeating freezing and degassing twice, 2
Polymerization was carried out at 0"C for 15 hours. The pressure during polymerization was lower than atmospheric pressure. As a result of polymerization, 16 g of polymer was obtained.

When we measured the infrared absorption spectrum of this polymer, we found that
1790 cm-' due to the double bond in the monomer
There was no nearby absorption. Further, when this polymer was dissolved in perfluorobenzene and a 19F NMR spectrum was measured, a spectrum showing the following repeating structure was obtained.

F2 0-CF.

The intrinsic viscosity [η] of this polymer is “Florinat” FC
-75 (Product name: Liquid mainly composed of perfluoro(2-butyltetrahydrofuran) manufactured by 3M Company, hereinafter referred to as FC
-75) at 30°C. The glass transition point of the polymer is 69°C, and it is a tough, transparent glass-like polymer at room temperature. In addition, the 1O% thermal decomposition temperature is 462°C, and furthermore, this polymer is colorless and transparent,
The refractive index was as low as 1.34, and the light transmittance was as high as 95%.

Synthesis Example 2 30 g of perfluoroallyl vinyl ether, 30 g of trichlorotrifluoroethane, and 10 mg of polymerization Tsuru initiator (C3F?C port) 2 were placed in a 50 cc pressure-resistant ampoule. 30 after repeating freezing and degassing twice
Polymerization was carried out at ℃ for 16 hours. The pressure during polymerization was below atmospheric pressure. As a result of the polymerization, 19 g of polymer was obtained.

The structure of the polymer was confirmed in the same manner as in Synthesis Example 1. The intrinsic viscosity [η] of this polymer is 30°C in FC-75 solution.
It was 0.32.

Synthesis Example 3 IOg of perfluoroallyl vinyl ether, Ig of tetrafluoroethylene, 30g of trichlorotrifluoroethane and polymerization initiator (C5FtCO)
5 mg of No. 2 was placed in a 100 cc pressure-resistant ampoule.

After repeating freezing and degassing twice, polymerization was carried out at 30° C. for 6 hours. As a result of polymerization, 4 g of polymer was obtained.

From the measurement of the F NMR spectrum, this copolymer-C
It was found to have a structure and composition similar to F2.

Synthesis Example 4 10g of perfluoroallyl vinyl ether, CF2.
CFO (CF2) *0.1g of C00Cls, log of trichlorotrifluoroethane and polymerization initiator (
C, F, CD).

5 mg was placed in a 500 cc pressure-resistant ampoule. After repeating freezing and degassing twice, polymerization was carried out at 30° C. for 16 hours.

As a result of polymerization, 2.8 g of polymer was obtained.

From the measurement of the 19F NMR spectrum, the following steps were repeated:
CF20 (cF21°■ C00CI+3) The composition was determined by titration of carboxylic acid groups.

Example 1 5 g of the polymer obtained in Synthesis Example 1 was added to 95 g of “Aflu-
Do”E-1n (Product name: Fluorine solvent manufactured by Asahi Glass Co., Ltd.)
dissolved in

This solution was cast onto a stainless steel substrate-1- and treated under a nitrogen stream at 40° C. for 16 hours and under reduced pressure at 110° C. for 5 hours to remove the solvent, and a 20 μm F film was formed. When it was peeled off from this thin substrate-1, it was a transparent film with no defects such as pinholes. The tensile strength of this membrane was 300 kg/cm" and the tensile elongation was 160%.

Example 2 The solution used in Example 1 was cast onto a glass plate and treated under a nitrogen stream at 40°C for 16 hours and under reduced pressure at 110°C for 5 hours to remove the solvent, and a 3μ thin film was formed.

Example 3 A plastic lens (diethylene glycol bisallyl carbonate type) was attached to the solution used in Example 1, and spin coding was performed. After spin coding at a spin speed of 1500 rpm for 5 seconds, the lens was dried at 60° C. for 1.5 hours in a nitrogen stream, and a 1 μm thin film was coated on the lens. This lens is used as a low-reflection processed lens.
can do.

Example 4 The solution used in Example 1 was applied to a quartz glass fiber, introduced into a heating curing furnace maintained at 400°C, and passed through for 2 seconds to form a 5 μ thick coating on the quartz glass fiber. An optical transmission fiber was obtained.

Example 5 1 g of the polymer of Synthesis Example 2 was mixed with 99 g of "Afluid" E-1
6 (trade name: fluorine-based solvent manufactured by Asahi Glass Co., Ltd.) and spin coded onto a metal substrate. spin speed is 500
Rotate for 1 minute at 0 rpm. After drying at 50°C, a 0.05μ thin film was formed on the metal substrate. The absence of pinholes in this thin film was confirmed by measuring the electrical resistance of this thin film, which was >10 ISΩcm.

Example 6 1 g of the copolymer of Synthesis Example 3 was dissolved in 19 g of perfluorobenzene. When an aluminum substrate was immersed in the solution mentioned above and dried at 40° C. for 1 hour, a 1.5 μm thin film was formed on the aluminum substrate.

Example 7 0.2 g of the copolymer of Synthesis Example 4 was dissolved in 20 g of FC-75, and a glass plate was immersed in this solution and dried at 40°C for 1.5 hours under a nitrogen stream, resulting in a 0.08μ thin film. was formed on a glass plate.

[Effects of the Invention] The present invention enables industrially smooth and advantageous production of thin films of 50μ or less by dissolving a perfluoropolymer having a ring structure in the main chain in a special solvent and forming a thin film using this solution. Furthermore, since a polymer having a perfluoro ring structure in its main chain is soluble in a solvent even if it is a homopolymer, even a polymer or copolymer with a high fluorine content is soluble. Therefore, the obtained thin film has the characteristics as a fluororesin, such as low refractive index, heat resistance, low moisture permeability,
High resistance, high dielectric breakdown strength, no loss of shade.

Furthermore, since it has a ring structure in its main chain, it has low crystallinity and can produce transparent thin films.

In the copolymer, comonomers having various useful functions can be selected, so that even more functions can be imparted to the thin film.

[℃Embedded (7F Physician) Toshiko Hiraishi

Claims (1)

[Claims] 1. The fluorine-containing polymer having a ring structure in its main chain has a thickness of 50 mm.
A thin film of a fluorine-containing polymer characterized by being thinned to less than μ. 2. Claim 1 in which the ring structure is a fluorine-containing ring structure
Thin film described in section. 3. The thin film according to claim 1 or 2, wherein the ring structure is a fluorine-containing ring structure containing an ether bond. 4. The thin film according to any one of claims 1 to 3, wherein the fluorine-containing polymer is a perfluoropolymer. 5. Claim 1 in which the ring structure is a 4- to 7-membered ring structure
The thin film according to any one of Items 1 to 4. 6. A method for forming a thin film, which comprises forming a thin film of the fluoropolymer having a thickness of 50 μm or less using a solution in which a fluoropolymer having a ring structure in its main chain is dissolved in a solvent. 7. Claim 6 in which the ring structure is a fluorine-containing ring structure
Thinning method described in section. 8. The method for forming a thin film according to claim 6 or 7, wherein the ring structure is a fluorine-containing ring structure containing an ether bond. 9. The method for forming a thin film according to any one of claims 6 to 8, wherein the fluorine-containing polymer is a perfluoropolymer. 10. The method for forming a thin film according to any one of claims 6 to 9, wherein the ring structure is a 4- to 7-membered ring structure.