JPH0762079B2 - Method for producing fluorine resin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a fluororesin film.

[Prior Art] A fluoropolymer generally has crystallinity, has a high melting point,
Alternatively, it has a large molecular weight and is difficult to melt and flow by heat. Therefore, when producing a fluororesin film, it is extruded at a high temperature of 300 ° C. or higher, or is cast from a dispersion with an organic solvent.

However, in the case of extrusion molding, a high temperature of 300 ° C. or higher and a high shearing force are required, and it is difficult to efficiently produce a thin film having a thickness of several tens μ or less. Also, even in the method of casting the dispersion of the organic solvent,
In order to melt and flow a high melting point fluoropolymer to obtain a uniform film, it is necessary to use a solvent having a special high boiling point in combination and to heat the polymer at a temperature higher than the melting point of the polymer. It has a drawback that the energy cost of heating at high temperature is high.

Also, the films obtained from these existing fluoropolymers are difficult to reheat and flow, and in order to be used as a coating material, thermal lamination at high temperature (for example, about 300 ° C (or higher) or lamination with an adhesive interposed) In addition, when a film containing various pigments, dyes, plasticizers, ultraviolet absorbers, etc., which are often required as a coating material, is to be obtained, it is necessary at the time of production.
Due to the high heat of ℃ or more, deterioration of the facial dye (yellowing) and escape due to sublimation of the plasticizer or the ultraviolet absorber occurred, and it was difficult to obtain a stable quality material.

[Problems to be Solved by the Invention] An object of the present invention is to solve the above-mentioned drawbacks of the prior art, that is, various drawbacks due to the need for a heating step at 300 ° C. or higher during the production of a fluororesin film. The present invention is intended to provide a method for obtaining a fluororesin film having a uniform and stable quality at a relatively low temperature.

[Means for Solving Problems] The present invention has been made to solve the above problems,
Fluorine content based on fluoroolefin unit is 10% by weight or more, intrinsic viscosity measured in tetrahydrofuran at 30 ° C is in the range of 0.05 to 2.0 dl / g, and solvent-soluble fluororesin should be formed into a film. The present invention also provides a method for producing a fluororesin film.

The fluorine content based on the fluoroolefin unit is 10% by weight or more as the fluororesin, polytetrafluoroethylene, tetrafluoroethylene-propylene copolymer,
Tetrafluoroethylene-isobutylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene- Perfluoro (alkyl vinyl ether) copolymers, etc., and fluoroolefins such as tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride and hexafluoropropylene, and copolymerizable monomers such as vinyl ether and vinyl ester. Examples thereof include copolymers with and, but in the present invention, a solvent-insoluble fluororesin is not adopted. Further, in the present invention, a fluororesin which is soluble in a solvent at room temperature is preferably adopted. Further, the crystalline fluororesin has a problem that it requires a high temperature for homogenization and it is difficult to produce a transparent film, which is not preferable and it is preferable to use a non-crystalline fluororesin.

Non-crystalline fluororesins that are soluble in solvents at room temperature include tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, fluoroolefins such as hexafluoropropylene, vinyl ethers, vinyl esters, etc. Examples thereof include copolymers with copolymerizable monomers. Preferred examples of vinyl ethers copolymerizable with fluoroolefins include linear, branched or alicyclic alkyl vinyl ethers having about 1 to 10 carbon atoms. Specific examples include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether and the like. Examples of the vinyl ether include hydroxybutyl vinyl ether, hydroxypropyl vinyl ether, glycidyl vinyl ether and the like, vinyl ether having a reactive group such as a hydroxyl group, an epoxy group and an amino group, or a part or all of hydrogen bonded to carbon is fluorine. Also included are fluoroalkyl vinyl ethers substituted with. Further, as the vinyl ester, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl caprate, vinyl laurate or a linear or branched aliphatic carboxylic acid vinyl ester such as vinyl stearate, Examples thereof include vinyl esters of alicyclic carboxylic acids such as cyclohexane cambonic acid vinyl ester, and vinyl esters of aromatic carboxylic acids such as benzoic acid vinyl ester.

In the present invention, preferred fluororesins include units based on fluoroolefins of 30 to 70 mol% and units based on vinyl ether and / or vinyl ester of 70 to 70% by mole.
30 mol% content, in uncured state in tetrahydrofuran 30
Intrinsic viscosity (hereinafter referred to as [η]) measured at ℃ is 0.05
It is about 2.0 dl / g. If the unit based on the fluoroolefin is smaller than the above range, physical properties such as weather resistance, which is a characteristic of the fluororesin, are not sufficient, and if the amount of vinyl ether and / or vinyl ester is smaller than the above range, It is not preferable because the solubility in a solvent is deteriorated and it becomes insoluble in the solvent at room temperature. On the other hand, if [η] is too small, a durable and tough film is difficult to be formed, and if [η] is too large, the melt viscosity of the fluororesin becomes extremely large, resulting in poor fluidity even at high temperatures. It is difficult to obtain a smooth, uniform, and thin film.

In the present invention, the method of forming the above-mentioned specific fluororesin into a film is not particularly limited, and solution cast molding, powder cast molding, extrusion molding or the like can be adopted. The cast molding method as described below is particularly preferable.

A method of casting a solution of a specific fluororesin in the present invention on a non-adhesive substrate is exemplified. Here, as the solvent for the specific fluororesin solution, a solvent that dissolves the specific fluororesin is adopted, but a solvent having too high viscosity and a solvent having a high boiling point are not preferable in terms of workability. Preferred solvents include aromatic compounds, ketones,
Examples thereof include esters, chlorinated hydrocarbon compounds, amide compounds, alcohols, petroleum-based thinners such as mineral spirits, and the like. As the base material, a base material having a smooth surface such as a glass plate, a metal plate or a synthetic resin sheet is adopted, but the surface is non-adhesive in order to facilitate the peeling of the film from the base material. Certain substrates are preferably employed. Examples of the base material having a non-adhesive surface include polytetrafluoroethylene resin, perfluoroalkoxy resin, ethylene-tetrafluoroethylene copolymer resin, tetrafluoroethylene-hexafluoropropylene copolymer resin, and silicone resin. Examples thereof include a substrate, a glass plate whose surface is treated with a silicone-based or fluorine-based release agent, a polyethylene terephthalate film, a metal plate, or the like. In the case where a specific fluororesin is formed into a film by such a method, it is sufficient to apply the fluororesin solution onto the substrate, evaporate and remove the solvent, and peel the formed film from the substrate. At this time, if necessary, additives such as pigments, dyes, ultraviolet absorbers, light stabilizers, plasticizers, and curing agents may be added to the fluororesin solution, or acrylic-based or epoxy-based solutions. Alternatively, the polyester resin may be dissolved. In addition, various coating methods can be adopted to uniformly coat the base material. For example, a method of applying using a flow coater, a coil coater, an air spray, or the like is exemplified.

As another film forming method, after pulverizing a specific fluororesin, it is sprayed on a base material, the fluororesin is heated, spread on the base material, and then cooled to form a film from the base material. A method of peeling is also exemplified. Here, since the specific fluororesin of the present invention is generally circulated in a solution state, in order to obtain a powdery fluororesin, a method of removing the solvent from the solution and pulverizing the obtained solid fluororesin is used. Adopted. Here, the pulverization is performed with a pulverizer such as a vibrating ball mill, a vibrating rod mill, a hammer mill, a tower mill, and a wheelet type pulverizer. It is preferable to carry out. If Tg of fluororesin is lower than room temperature, dry ice or liquid nitrogen is used to cool the fluororesin to below Tg and then grind, or dry ice and liquid nitrogen are ground together with fluororesin. It is preferable to lower the crushing environmental temperature to Tg or lower of the fluororesin by a method such as supplying to a machine. The particle size of the fluororesin powder is preferably 0.1 to 500 μ, and more preferably 5 to 200 μ. A powder having an excessively large particle size is not preferable because it has a poor thermal conductivity and makes it difficult to uniformly melt and flow to obtain a uniform film. In addition, a powder having an excessively small particle size is not preferable because it is likely to be charged with static electricity and is difficult to handle during transportation and spraying. Further, as the base material, the same base material as the base material described in the film forming method using the solution described above is adopted. In addition, various methods are adopted as a method for dispersing the fluororesin powder on the base material. For example, methods such as fluidized dipping and electrostatic spraying are exemplified. Further, the optimum heating conditions differ depending on the type of fluororesin, but it is preferable to heat to a temperature above the temperature at which the fluororesin melts and flows. Further, in order to save energy and prevent thermal deterioration of the substrate, it is not preferable to heat at a too high temperature, and it is preferable to heat at 300 ° C. or lower, particularly 250 ° C. or lower. The film forming method using such powdery fluororesin is preferable because a film without pinholes can be produced in a relatively short time.

The shaped fluororesin film may be blended with the additives as described above. The curing agent may be reacted with the fluororesin during molding, or may be reacted after forming a film. In the former case, a fluororesin film cured with a curing agent is obtained. In the latter case, the obtained film can be crosslinked by secondary processing and is useful as an adhesive film. In this case, for example, a blocked polyisocyanate is used as the curing agent, a film is produced at a temperature at which this block is difficult to be removed, and then secondary processing is performed at a temperature at which this block is removed. The fluororesin film containing the unreacted curing agent can be used in various applications utilizing its properties such as adhesiveness and secondary processability.

Example 1 A xylene solution of a fluororesin in which units based on tetrafluoroethylene, ethyl vinyl ether and cyclohexyl vinyl ether are 48.5 / 18.7 / 32.8 by weight and [η] is 0.19 dl / g is heated. It was obtained by removing the solvent. 100 g of the solid fluororesin was pulverized by using a Wille pulverizer while being cooled with dry ice to obtain a fluororesin powder having a particle size of 200 μ or less. This fluororesin powder is sprinkled on a glass plate, melted and fluidized at 200 ° C for 10 minutes, then immersed in water for 30 minutes, then peeled off from the glass plate to a thickness of
A 50 μm transparent fluororesin film was obtained. When this film was immersed in xylene, it completely dissolved.
The tensile strength of this film (based on JIS Z1702) is 1
56 kg / cm ² , tensile elongation (according to JIS Z1702) was 62%.

Example 2 The same as Example 1, except that the weight ratio of the units based on chlorotrifluoroethylene and cyclohexyl vinyl ether was 47.2 / 52.8, and the [η] was 0.39 dl / g. A transparent fluororesin film having a thickness of 40 μm was obtained. This fluororesin film has a tensile strength (according to JIS Z1702) of 530 kg / cm ² and a tensile elongation (JI
(According to S Z1702) was 3%. Moreover, this fluororesin film was completely dissolved in xylene.

Example 3 Units based on chlorotrifluoroethylene, cyclohexyl vinyl ether, ethyl vinyl ether, hydroxybutyl vinyl ether are 49.5 / 24.9 / in weight ratio, respectively.
A transparent fluororesin film having a thickness of 50 μm was obtained in the same manner as in Example 1, except that a xylene solution of fluororesin having a ratio of 14.2 / 11.5 and [η] of 0.23 dl / g was used. The tensile strength of this fluororesin film (according to JIS Z1702) is 450 kg / c.
The m ² and the tensile elongation (according to JIS Z1702) were 7%. The fluororesin film was completely dissolved by immersing it in a xylene solution. In addition, this fluororesin film,
Two aluminum plates (thickness 0.8mm A5052 material; Alodine # 1000
The bonded body was sandwiched between the materials subjected to chemical conversion treatment in ^{2. and} pressed by a hot press at a pressure of ² kg / cm ² at 190 ° C. for 10 minutes to obtain a joined body.
The adhesive strength of the joint thus obtained (tensile shear force: ASTM D1
002) was 75 kg / cm ² .

Example 4 Units based on chlorotrifluoroethylene, cyclohexyl vinyl ether, ethyl vinyl ether, hydroxybutyl vinyl ether are 53.1 / 11.6 /
14.0 / 21.3 and [η] 0.07 dl / g fluororesin, blocked isocyanate (Coronate DC2725 made by Nippon Polyurethane) 35 phr and rutile type titanium oxide (made by Ishihara Sangyo: trade name CR 90) 43 phr, MIBK ( (Methyl isobutyl ketone) solution is applied on a glass plate treated with silicone release agent using a flow coater, then at 80 ℃
After heating for 30 minutes, cool and peel from the glass plate to a thickness of 20
A white fluororesin film having no color unevenness was obtained. Tensile strength of this fluororesin film (based on JIS Z1702)
Was 380 kg / cm ² and the tensile elongation (according to JIS Z1702) was 10%. Further, when this fluororesin film was immersed in MIBK, it was completely dissolved. Further, using this fluororesin film, the adhesive strength measured in the same manner as in Example 3 was 105 kg / cm ² . In addition, the bonded body maintained its adhesive strength even after being immersed in MIBK overnight. Further, using this fluororesin film, a fluororesin film / aluminum plate laminate was obtained by the following method. Aluminum plate (A5052
Superimposing a fluororesin film to chemical conversion treated surface by Alodine # 1000 agent), it was further superposed a polytetrafluoroethylene resin film, 190 ° C. at a pressure of 0.2 kg / cm ^2, then heat treated for 10 minutes, polytetra By peeling off the fluoroethylene resin film, a fluororesin film / aluminum plate laminate was obtained. The adhesiveness of this laminate (separation test for scoring of goggles) was 100/100. In addition, this laminated body is MIB
Even after being soaked in K overnight, the fluororesin film layer was a white color with surface gloss and uniform color, and the adhesiveness was also retained.

Example 5 Tetrafluoroethylene, cyclohexyl vinyl ether, ethyl vinyl ether, hydroxybutyl vinyl ether and units based on succinic acid esters of hydroxybutyl vinyl ether are in a weight ratio of 50.3 / 19.0 /, respectively.
Fluorine resin with 19.1 / 10.4 / 1.2 and [η] of 0.45 dl / g, ε-caprolactam blocked isophorone diisocyanate (manufactured by Sumitomo Bayer Urethane; trade name Klelan UI) 25 phr and 1-hydroxy-3- A transparent fluororesin film having a thickness of 25 μm was obtained in the same manner as in Example 4 except that a solution of a xylene / MIBK mixed solvent containing 10 phr of octoxybenzophenone (weight ratio 2/1) was used. Tensile strength of this fluororesin film (based on JIS Z1702)
Was 114 kg / cm ² , the tensile elongation (according to JIS Z1702) was 110%, and the light transmittance at a wavelength of 360 nm was 0%.
Further, the adhesive force measured using this fluororesin film in the same manner as in Example 3 was 90 kg / cm ² , and the adhesive force was maintained even after the immersion in MIBK overnight. Furthermore, the adhesion measured using this film in the same manner as in Example 4 was 100/10.
It was 0, and the fluororesin film layer was transparent even after overnight immersion in MIBK, and the adhesiveness was maintained.

Example 6 A unit based on tetrafluoroethylene, ethyl vinyl ether, and glycidyl vinyl ether had a weight ratio of 54.9 / 32.8 / 12.3, and [η] was 0.21 dl / g. Xylene
Example 4 except that the / MIBK mixed solvent (weight ratio 2/1) solution is used
A transparent fluororesin film having a thickness of 30 μ was obtained in the same manner as in. Tensile strength of this fluororesin film (JIS Z1702
95 kg / cm ² and tensile elongation (according to JIS Z1702) 6
It was 0%. In addition, the adhesive force measured using this fluororesin film in the same manner as in Example 3 was 120 kg / cm ² , and the adhesive force was maintained even after overnight immersion in MIBK. Furthermore, using this film, the adhesion measured in the same manner as in Example 4 was 100/100, and the fluororesin film layer was transparent even after overnight immersion in MIBK, and the adhesion was maintained.

[Effect of the Invention] According to the manufacturing method of the present invention, there is an effect that a thin film having excellent weather resistance can be efficiently manufactured at a relatively low temperature. In addition, since the fluororesin film obtained by the production method of the present invention has excellent adhesiveness, it is possible to carry out weatherproof coating on various base materials without applying special adhesive means such as an adhesive. . Further, by using the non-crystalline fluororesin, a film having excellent transparency can be produced, and a clear weatherproof coating can be performed. Also, since the film is formed at a relatively low temperature, even if various additives such as pigments, dyes, ultraviolet absorbers and light stabilizers are blended to produce the film, the additives will not be altered. . Therefore, it is possible to manufacture a fluororesin film having various properties such as a weather resistant colored coating material. Further, by producing a fluororesin film using a fluororesin powder, it is possible to produce a fluororesin film having no pinhole, that is, more excellent weather resistance and the like.

Further, the method for producing a fluororesin film produced by the production method of the present invention can be applied to an adhesive by using the adhesive.

Claims (2)

[Claims] 1. A fluorine content of 10% by weight or more based on a fluoroolefin unit and 30 ° C. in tetrahydrofuran.
Intrinsic viscosity measured in the range of 0.05 ~ 2.0dl / g,
A method for producing a fluororesin film, which comprises forming a film of a fluororesin soluble in a solvent. 2. The method according to claim 1, wherein the fluororesin or its solution is formed into a film on a non-adhesive substrate.