JP2962459B2 - Liquid crystal polymer film and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal polymer film and a method for producing the same.

[0002]

2. Description of the Related Art Liquid crystal polymers are liquid crystal polymers that exhibit liquid crystallinity in a solution state or a molten state, and are classified into rheotropic liquid crystal polymers that exhibit liquid crystallinity in a solution state and thermotropic liquid crystal polymers that exhibit liquid crystallinity in a molten state. It is roughly divided. Liquid crystal polymers, especially thermotropic liquid crystal polymers, have excellent properties such as high strength, high heat resistance, low linear expansion coefficient, high insulation, low moisture absorption, and high gas barrier properties, and have already been put into practical use as injection molded parts and fibers. ing. In addition, a film using a liquid crystal polymer is also used for electronic materials
C, its use is expected for packaging and the like. However,
When a liquid crystal polymer film is melt-extruded from a die for processing, its molecules are significantly oriented in the direction of extrusion,
Since the film is easily oriented, the film may be cracked in the machine direction (MD), or even if there is no crack, the film may have a tensile strength, a tensile elongation in the machine direction (MD) and a width direction (TD). There is a problem that the anisotropy of physical properties such as tensile modulus is large.

For this reason, the MD / T of liquid crystal polymer film
It has been proposed a technique for alleviating the anisotropy in D, for example due to inflation as a technique for alleviating the anisotropy in MD / TD (KOKOKU 01-34134, JP-A No. 03-152131, JP-A No. 05-
No. 43664) Inflation method using a rotating die (Japanese Patent Application Laid-Open Nos. 63-199622, 01-130930, and 02-89616).
And Japanese Patent Publication No. 04-506779). However, in the liquid crystal polymer films obtained by these methods, although the problem of physical property balance in MD / TD is basically solved, the surface roughness inherent to the liquid crystal polymer (poor surface smoothness, uneven thickness, streaks, etc.) However, it is necessary to use a liquid crystal polymer having a special structure and an inflation die, which are not commercially available and have a special structure, because they are apt to curl due to making a cut in the tubular shape.
In addition, since a rotating die basically performs multi-layer extrusion, the orientation of each layer is only in a single direction, and there remains a problem that the surface layer is easily peeled in a fibril shape in the oriented direction. In addition, as a device using a flat die,
A method of intersecting the orientation of each layer of a multilayer flat die (Japanese Patent Application Laid-Open No. 02-89617, Japanese Patent Application Laid-Open No. 63-264323) and a method of applying a magnetic field in the land portion of the flat die in the horizontal direction (Japanese Patent Application Laid-Open No. 63-242513) are proposed. Have been. However, liquid crystal polymer films obtained by these methods have the same problems as described above, and although these methods are possible as ideas, it is actually difficult to obtain a homogeneous film with reduced anisotropy. .

Therefore, as a method for improving the surface properties of a liquid crystal polymer film, a method of extruding a liquid crystal polymer at a shear rate equal to or higher than the inflection point of viscosity and shear rate (Japanese Patent Laid-Open No. Hei.
No. 107424), a method using a static mixing stirrer at the die inlet (Japanese Patent Application Laid-Open No. 2-107427), and a method using noble metals at the lip contact portion of the die (Japanese Patent Application Laid-Open No. 1-2).
No. 81915). However, the liquid crystal polymer film obtained by these methods is a film using a thermotropic liquid crystal polymer, which has a high processing viscosity without using a solvent, although the surface property is improved with a film using a rheotropic liquid crystal polymer. The effect of improving the surface properties was small.

A calender roll is used to calender the liquid crystal polymer film or sheet at a temperature within the range of the glass transition temperature or higher and the melting temperature or lower. T
D. A film with a good balance (Japanese Unexamined Patent Publication No.
However, unlike a normal crystalline resin, the melt viscosity of a liquid crystal polymer changes abruptly near a liquid crystal transition temperature (dissolution temperature), and therefore, even if calendering is performed at a temperature lower than the melting temperature. The viscosity is too high to obtain the desired product. Furthermore, in any of the above-described methods, when an ultra-thin liquid crystal polymer film was to be obtained by stretching at a high magnification, it was difficult to obtain a film having a thickness of 20 μm or less due to the occurrence of cracks.

A method of co-extruding a non-liquid crystal polymer such as polyester and a liquid crystal polymer (Japanese Patent Laid-Open No. 63-317)
No. 29, JP-A-02-178016), it is not possible to obtain a film that is satisfactory in terms of the balance of physical properties in the vertical and horizontal directions.

Further, a thin film containing a liquid crystal material using a synthetic resin porous body (Japanese Patent Application Laid-Open No. 02-175737) is also known, which is a liquid crystal thin film having a strength which cannot be obtained by the solvent evaporation method or the water surface spreading method. However, the liquid crystal substance used is a low-molecular liquid crystal substance, has no film forming ability itself, and is also used for a liquid crystal functional element such as a liquid crystal display. It is not used for electronic materials and packaging materials that take advantage of the high strength, high heat resistance, low coefficient of linear expansion, high insulation, low moisture absorption, and high gas barrier properties of liquid crystal polymers with film forming ability. Are different.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, and is free from cracks, curls, surface peeling and MD regardless of the type of liquid crystal polymer used.
It is an object of the present invention to provide a liquid crystal polymer film which is excellent in physical property balance, surface smoothness, strength, etc. in / TD and can be made extremely thin, and a method for producing the same.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, a liquid crystal polymer film obtained by stretching a laminate of a resin film comprising a liquid crystal polymer or liquid crystal polymer from the polymer alloy as a component and a synthetic resin porous film is provided, also, the synthetic resin The liquid crystal polymer film is provided, wherein the porous film is a fluororesin porous film, and further, the laminate is a liquid crystal polymer or a polymer alloy containing a liquid crystal polymer as a component. Wherein the liquid crystal polymer film is laminated with a synthetic resin porous film . According to the present invention, there is provided a liquid crystal polymer film obtained by stretching a synthetic resin porous film impregnated with a resin made of a liquid crystal polymer or a polymer alloy containing a liquid crystal polymer as a component, and the synthetic resin porous film is provided. Wherein the liquid crystal polymer film is a fluororesin porous film. Further, according to the present invention, the method comprises a step of laminating a resin film made of a liquid crystal polymer or a polymer alloy containing a liquid crystal polymer as a component and a synthetic resin porous film , and a step of stretching the laminate obtained in the step. A method for producing a liquid crystal polymer film is provided, further comprising , according to the present invention, a step of impregnating the synthetic resin porous film with a resin made of a liquid crystal polymer or a polymer alloy containing the liquid crystal polymer as a component, There is provided a method for producing a liquid crystal polymer film, comprising a step of stretching the impregnated film obtained in the step.

Hereinafter, the present invention will be described in detail.
In the present invention, the film includes a so-called film, sheet, and thin film. The first liquid crystal polymer film according to the present invention is combined with a resin film made of a liquid crystal polymer or a polymer alloy containing a liquid crystal polymer as a component.
It is characterized in that a laminate with a synthetic resin porous film is stretched.

As the liquid crystal polymer used in the present invention, a thermotropic liquid crystal polymer and a rheotropic liquid crystal polymer can be used. Among these, thermotropic liquid crystal polymer, for example, aromatic diol, aromatic carboxylic acid, aromatic polyester synthesized from monomers such as hydroxycarboxylic acid, there is an aromatic polyester that exhibits liquid crystallinity when melted, as typical examples thereof, A first type comprising parahydroxybenzoic acid (PHB), terephthalic acid and biphenol (formula 1 below); a second type comprising PHB and 2,6-hydroxynaphthoic acid (formula 2 below); PHB And terephthalic acid and ethylene glycol.

[0012]

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[0013]

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[0014]

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On the other hand, examples of the rheotropic liquid crystal polymer include, but are not limited to, a concentrated sulfuric acid solution of poly (p-phenylene terephthalamide) (PPTA), an aqueous solution of silk fibroin, and an aqueous solution of sericin represented by the following formula (4).

[0016]

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In the present invention, instead of using the liquid crystal polymer alone, a polymer alloy containing the liquid crystal polymer as a component may be used. In this case, as the polymer to be mixed or chemically bonded with the liquid crystal polymer, polyetheretherketone, polyethersulfone, polyimide, polyetherimide, polyamide, polyamideimide, polyarylate, and the like can be used, but not limited thereto. .
The mixing ratio of the polymer and the liquid crystal polymer is 10:
90-90: 10 is preferred, and 30: 7 is more preferred.
0 to 70:30.

According to the present invention, additives such as a compatibilizer, a plasticizer, a flame retardant, or an inorganic powder, a fiber, or the like may be added to a resin comprising a liquid crystal polymer or a polymer alloy containing a liquid crystal polymer as a component, depending on the purpose of use. And the like.

The synthetic resin porous material constituting the porous synthetic resin film used in the present invention has uniform continuous pores on the order of microns, does not tear at the temperature at the time of stretching, does not melt, and has heat resistance, heat resistance, and the like. Any corrosive material can be used. Specifically, polyolefin porous bodies such as polyethylene and polypropylene, polycarbonate porous bodies, polystyrene porous bodies, polyvinyl chloride porous bodies, polyester porous bodies, polytetrafluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymers, polyfluorinated Fluororesin porous bodies such as vinyl, polyvinylidene fluoride and poly (trichloroethylene chloride) can be exemplified. Of these, a porous fluororesin body is preferably used, and in view of heat resistance and chemical resistance, expanded porous polytetrafluoroethylene is particularly preferable. The average pore diameter of the synthetic resin porous film is 0.05 to 5.0 μm, preferably 0.2 to 1.0 μm, and the porosity is 40 to 95 μm.
%, Preferably 60 to 85%, and the thickness is 5 to 300%.
μm, preferably 20 to 150 μm.

[0020] and the resin film formed of a polymer alloy according to the liquid crystal polymer or liquid crystal polymer component, synthetic resin multi
Lamination with the porous film can be performed, for example, by passing between heated metal rolls. In this case, a plurality of the resin film and the synthetic resin porous film may be laminated, and the upper and lower relation between them may be arbitrary. In the laminate using the synthetic resin porous film, it is desirable that at least 1/10 or more of the resin film in the thickness direction enter the pores of the synthetic resin porous film after lamination. When laminating a resin film made of a thermotropic liquid crystal polymer or a polymer alloy containing the same and a synthetic resin porous film , lamination may be performed immediately after the resin film comes out of an extrusion die, It may be performed after cooling, but in the latter case, the temperature of the metal roll needs to be higher by about 10 to 50 ° C. than the melting point of the resin. Speaking of the structure of the laminate, it is synthesized on both sides of the resin film.
A laminated resin porous film is very preferable in view of easiness of production and the like. Reotoropikku a polymer alloy of a liquid crystal polymer or which component resin film and covering
When laminating with a synthetic resin porous film , the wet-processed resin film processed as described above is made of synthetic resin.
It is preferable to laminate on a porous film .

The liquid crystal polymer film of the present invention is obtained by stretching the laminate. In the case of a laminate of a resin film made of a thermotropic liquid crystal polymer or a polymer alloy containing the same as a component and a synthetic resin porous film , biaxial stretching is preferable from the viewpoint of a balance of physical properties in MD / TD. A simultaneous biaxial stretching machine and a sequential biaxial stretching machine used for stretching a plastic resin can be used. At this time, the temperature is set to a temperature higher than the temperature at which the liquid crystal polymer sufficiently shows a liquid crystal state. Although the stretching ratio depends on the thickness of the original film and the film to be obtained, it is usually 1.5 to 15%.
Times, preferably 4 to 8 times. Stretching speed is usually 5-5
00% / min, preferably 20 to 100% / min. In order to stabilize physical properties such as dimensional stability of the liquid crystal polymer film, it is desirable to perform annealing after stretching. Annealing varies depending on the resin used, but it is generally preferable to perform annealing at a temperature higher than the stretching temperature and higher than the cooling crystallization temperature. By adjusting the MD / TD stretching ratio and stretching speed, a film having an arbitrary MD / TD physical property balance can be obtained. In the case of a resin film composed of a rheotropic liquid crystal polymer or a polymer alloy containing the same and a porous synthetic resin film , MD /
Biaxial stretching is preferable from the viewpoint of physical property balance in TD. For example, biaxial stretching is performed in the vertical and horizontal directions using nip rolls and tenters having different peripheral speeds. At this time, biaxial stretching is performed while the laminate is wet and wet. Although the stretching ratio depends on the thickness of the original sheet and the film to be obtained, it is usually 1.1 to 1.1.
It is 10 times, preferably 1.2 to 5 times. The stretching speed is usually 3 to 300% / min, preferably 5 to 50% / mi.
n. After that, heating, drying of residual solvent and water,
Perform removal.

The second liquid crystal polymer film according to the present invention is characterized in that a synthetic resin porous film impregnated with a resin comprising a liquid crystal polymer or a polymer alloy containing a liquid crystal polymer as a component is stretched. In this case, as the resin and the synthetic resin porous film made of the liquid crystal polymer or the polymer alloy containing the liquid crystal polymer as the component, the same materials and those having the required characteristics as described above can be used. As a method of impregnating a synthetic resin porous film with a liquid crystal polymer or a resin made of a polymer alloy containing a liquid crystal polymer as a component, for example, a method such as dipping or coating can be used. The impregnation amount of the above resin composition is such that the percentage of filling the pores is 50 to 100%, preferably 80 to 100%.
It is an amount such that The liquid crystal polymer film of the present invention is obtained by stretching a synthetic resin porous film impregnated with the above resin . The stretching ratio depends on the thickness of the original film and the film to be obtained, but is the same for thermotropic and rheotropic as in the case of the respective laminates. In order to stabilize the physical properties of the liquid crystal polymer film, it is preferable to perform annealing after stretching, as described above.

[0023] Oite the present invention, a synthetic resin porous film to be used has a fine and homogeneous continuous pores of micron order, it is possible to follow to the stretching of any magnification, laminated thereto The stretched liquid crystal polymer or the liquid crystal polymer that has entered the porous structure is subjected to stretching force very uniformly even when viewed microscopically in the stretching process, and as a result, a film having extremely excellent surface properties is obtained. Further, for the same reason, since the film is not torn even when stretched at a high magnification, an extremely thin film can be formed. It is difficult to stretch a film composed of only a liquid crystal polymer at a high magnification due to the orientation and domain properties of the liquid crystal polymer. Therefore, an extremely thin film could not be obtained, whereas the liquid crystal polymer film of the present invention has a thickness of 2 μm. Ultra-thinness to the extent possible is possible. Also,
Among the synthetic resin porous bodies, the fluororesin porous body is excellent in heat resistance and is suitable for those requiring stretching of a liquid crystal polymer exhibiting a liquid crystal state at a high temperature of 200 ° C. or higher or drying at a similar temperature.

[0024]

As described in detail above, according to the present invention, regardless of the type of liquid crystal polymer used, there are no cracks, curls, or surface peeling, and the balance of physical properties in MD / TD, surface smoothness, strength, etc. The present invention provides a liquid crystal polymer film which is excellent in quality and can be made extremely thin. And
The liquid crystal polymer film of the present invention has high strength, high heat resistance,
Excellent in low coefficient of linear expansion, high insulation, low moisture absorption, high gas barrier property, etc., and is useful for applications as electronic materials, packaging materials and the like.

[0025]

EXAMPLES Next, examples of the present invention will be described, but the present invention is not limited to these examples.

[0026]Example 1  Thermotropic liquid crystal polymer (Polyplastics)
Manufactured by Bestra A-950) and a single screw extruder (screw
Diameter 50mm) and inflation type rotating die (SUS
304, die diameter 100mm, blow ratio 1.2, die
Lip rotation speed 7rpm, die temperature 300 ℃, take-off speed
Extruded with a thickness of 110μ
m of the resin composition sheet was obtained. Then the laminating machine
Between metal rolls (roll temperature 330 ° C, pressure 3kg / c
m^Two) To stretch both sides of the resin composition sheet
Porous PTFE film (average pore size 0.5 μm, porosity
80%, thickness 50 μm). Then Lami
The nate body is sequentially biaxially stretched in a biaxial stretching machine (temperature 29
5 ° C., stretching ratio 4 times, stretching speed 100% / min),
Finally, annealing (240 ° C., 3 minutes), thickness 10 μm
Was obtained.

[0027]Example 2  Rheotropic liquid crystal polymer (PPTA polymer 15
% Concentrated sulfuric acid solution) using a static mixing stirrer at the inlet.
Expanded porous PTFE film on cast belt by die
Lum (average pore diameter 0.5 μm, porosity 80%, thickness 40μ)
m) Cast and impregnated on top, and the entire belt with sulfuric acid aqueous solution
Feeded in and solidified. Then the impregnated film
Peeled off and washed in water. Repeat this series four more times
55% of pore volume of repetitive film is rheotropic
Filled with liquid crystal polymer. Next, at room temperature,
With a roll and a tenter in the vertical and horizontal directions with respect to the impregnated film
Biaxial stretching (drawing ratio 2 times, stretching speed 1m / min)
And then dried (200 ° C, 10 minutes) to a thickness of 10μ
m was obtained.

Comparative Example 1 A film was obtained in the same manner as in Example 1, except that the expanded porous PTFE film was not laminated on both sides.

Comparative Example 2 A thermotropic liquid crystal polyester (manufactured by Polyplastics: Bestra A-950) was fed to a single screw extruder (screw diameter 50 mm) and an inflation type rotating die (S
US304, die diameter 100mm, blow ratio 1.2,
The film was extruded at a die lip rotation speed of 30 rpm, a die temperature of 300 ° C. and a take-up speed of 10 m / min) to obtain a film having a thickness of 50 μm.

Comparative Example 3 A film was obtained in the same manner as in Comparative Example 2 except that the material of the die lip was made of tantalum having a thickness of 5 mm on the side in contact with the resin.

Comparative Example 4 A film was obtained in the same manner as in Example 2, except that a cast film of a rheotropic liquid crystal polymer having a thickness of 40 μm was used instead of using the expanded porous PTFE film.

Each film obtained above was examined for tears, and the surface roughness, tensile strength and tensile elongation were measured. Tensile strength and tensile elongation were based on JIS K 7127. In the case of Comparative Examples 1 and 4, since many tears occurred during stretching, other items were not measured .

[0033]

[Table 1]

The measuring method is as follows.According to  Thickness: Dial gauge Rip: Visual inspection Surface peeling: Lightly rubbing with sandpaper, surface fibri
See if there is a file. (Example 1Is evaluated by peeling the surface resin film) Surface roughness: JIS B0601 Surface roughness meter Tokyo Seimitsu Surfcom 1500A (Example 1Is evaluated by peeling the surface resin film) Tensile strength: JIS K 7127 Tensile elongation: JIS K 7127

Claims (7)

(57) [Claims] 1. A resin film comprising a liquid crystal polymer or a polymer alloy containing a liquid crystal polymer as a component and a synthetic resin
A liquid crystal polymer film obtained by stretching a laminate with a porous film . 2. The liquid crystal polymer film according to claim 1, wherein the synthetic resin porous film is a fluororesin porous film. 3. The laminated body according to claim 1, wherein the synthetic resin porous film is laminated on both sides of a resin film made of a liquid crystal polymer or a polymer alloy containing a liquid crystal polymer as a component. Liquid crystal polymer film. 4. A liquid crystal polymer film obtained by stretching a synthetic resin porous film impregnated with a resin comprising a liquid crystal polymer or a polymer alloy containing a liquid crystal polymer as a component. 5. The liquid crystal polymer film according to claim 4, wherein said synthetic resin porous film is a fluororesin porous film. 6. A resin film comprising a liquid crystal polymer or a polymer alloy containing a liquid crystal polymer as a component and a synthetic resin
A method for producing a liquid crystal polymer film, comprising: a step of laminating a porous film ; and a step of stretching the laminate obtained in the step. 7. A process comprising: impregnating a synthetic resin porous film with a liquid crystal polymer or a resin comprising a polymer alloy containing the liquid crystal polymer as a component; and stretching the impregnated film obtained by the process. A method for producing a liquid crystal polymer film.