JPH02239919A - Production of longitudinal direction strengthened biaxially oriented polyether ketone film - Google Patents

Abstract

PURPOSE:To stabilize film formation properties by firstly stretching an unstretched film of polyether ketone in the lengthwise direction so that specified birefringent index is obtained and then stretching this film in the transverse direction and furthermore performing retardation treatment and thereafter restretching the film in the lengthwise direction. CONSTITUTION:An unstretched film of polyether ketone I is stretched to the lengthwise direction so that birefringent index is regulated to 0.02 or more and less than 0.07. The temp. in longitudinal stretching is regulated to transition temp. or more of glass and 200 deg.C or below. The longitudinally stretched film is stretched to the transverse direction in stretching magnification of 3.0 times or more so that the refractive index of the transverse direction is made larger than the refractive index of the lengthwise direction. Furthermore the biaxially oriented film after transverse stretching is thermally fixed at the transverse stretching temp. or more and 320 deg.C or below and retarded (shrinkage retardation) at 3-30% to the transverse direction (width direction). Thereafter this film is restretched in the lengthwise direction at the temp. not higher than the above-mentioned thermally fixing temp. This film is thermally fixed in accordance with necessity after longitudinal restretching. In such a way, the longitudinal direction strengthened biaxially oriented polyether ketone film which has both >=600kg/mm<2> Young's modulus of the lengthwise direction and <=10% thickness irregularity of the lengthwise and transverse directions is obtained in a stable processing stage.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for producing a biaxially oriented polyetherketone film strengthened in the longitudinal direction, and more specifically, to a method for producing a biaxially oriented polyetherketone film that is strengthened in the longitudinal direction, and more specifically, has a method for producing a biaxially oriented polyetherketone film that is strengthened in the longitudinal direction and has small thickness unevenness in the longitudinal and lateral directions, and has high strength in the longitudinal direction. The present invention relates to a method for producing an excellent biaxially oriented polyether carbon film.

(Prior art and its problems) Biaxially oriented polyethylene terephthalate film has been widely used in industrial applications due to its excellent mechanical properties, electrical properties, heat resistance, and chemical resistance. It is being

However, in recent years, the required properties of films have increased depending on the application, and there are limits to the properties of biaxially oriented polyethylene terephthalate films, so there is a demand for films with even more excellent properties. For example, biaxially oriented polyethylene derephthalate 1 film has a long-term heat resistance of E
Type (long-term heat resistance temperature: 125℃) or B type (long-term heat resistance temperature: 130℃)
℃), and when used as motor insulation or wire coating material, there is a problem in that miniaturization of motors is restricted due to long-term heat resistance. Further, when the above film is used for a capacitor, the dielectric loss tangent increases from around 85° C., which limits the operating temperature. Furthermore, when the above-mentioned film is used as a flexible printed circuit board, the heat resistance of the hank becomes a problem, and its development is limited. For these reasons, there is a demand for films with even better heat resistance.

By the way, polyetherethercane is known as a crystalline thermoplastic polymer that is tough and has excellent heat resistance (Japanese Patent Publication No. 60-32642, Japanese Patent Publication No. 61-10486).
(No.), the development of this film is being considered and proposed. For example, JP-A-57-137166 discloses that polyetheretherkene I~ is used in fields that take advantage of its heat resistance, ie, insulating films for motors, 1~ insulating films for lances. 6 JP-A-58-63417 describes a method for manufacturing a uniaxially oriented film using a rolling method, which is expected to be applied to insulating films for capacitors, flexible printed circuit boards, etc. , a method for producing isotropic biaxially oriented polyether ether ketone films is described.

Japanese Unexamined Patent Publication No. 60-93625 describes a perpendicularly magnetized polyester edelken film which is biaxially oriented by a rolling method.

However, according to the research results of the present inventors, these biaxially oriented films are not high-strength films and have a low Young's modulus, and it is difficult to make thin films using these methods. It has become clear that there is a problem in that the Young's modulus is limited to fields where Young's modulus is not particularly required6.Furthermore, although methods for producing biaxially oriented polyethergetone films with high strength in the longitudinal direction have been proposed, It has become clear that this method has problems in terms of thickness unevenness, and that attempting to improve the thickness unevenness results in frequent cutting, which impairs the stability of the process. The present invention uses polyetherketone resin, particularly polyetherketone resin, to produce a biaxially oriented film with excellent longitudinal mechanical strength, small thickness unevenness, and stability in the longitudinal direction. As a result of intensive research into the method, we found that the unstretched polyethergetone film was first stretched longitudinally to a specific birefringence, then stretched transversely, further subjected to a relaxation treatment, and then stretched again longitudinally, thereby increasing its strength in the longitudinal direction. The present inventors have discovered that it is possible to produce a biaxially oriented polyetherketone film with stable film formability, and have completed the present invention.

That is, in the present invention, an unrolled polyetherketone intermediate film is rolled so that the birefringence becomes 0.02 or more and less than 0.07 at a temperature higher than the glass transition temperature and lower than 200°C, and then the refractive index in the transverse direction is A biaxially oriented film is obtained by horizontally stretching the refractive index in the longitudinal direction at a stretching ratio of 3.0 times or more, and the axially oriented film is then heated at a temperature of 2,320°C or less above the horizontal stretching temperature. After being heat-set and relaxed by 3 to 30% in the transverse direction, it is longitudinally stretched again at below the above heat-setting temperature, and then heat-set as necessary, so that the Young's modulus in the longitudinal direction is f300 mr/1 or more and , a method for producing a biaxially oriented polyetherketone film strengthened in the longitudinal direction, characterized in that the film has thickness unevenness of 10% or less in the longitudinal and lateral directions.

The polyetherketone used in the present invention is the following '! !
It is a polymer consisting of the 4 structural unit alone or this unit and other lateral units.6 What are some examples of other structural units? can be raised. In the Yang Cheng unit, A is a direct bond, oxygen, -SO■-, monoCO- or a divalent lower aliphatic hydrocarbon group, and Q and Q' may be the same or different; - C Q- or SO 2-, and n is 0 or 1. These polymers are
It is described in Japanese Patent Publication No. 0-32642, Japanese Patent Publication No. 61-10486, Japanese Patent Application Laid-Open No. 57-137116, etc. A typical polymer includes a polymer consisting of structural units (polyether ether ken resin).

Polyether genes 1 to 1 may be blended with resins such as polyarylene polyether, polysulfone polyarylate, polyester, and polycarbonate for the purpose of improving fluidity, and may also be blended with lubricants, stabilizers, antioxidants, ultraviolet absorbers, etc. It may also contain additives such as.

Preferred lubricants include: ■ Calcium carbonate, ■ Silicon dioxide (including hydrates, diatomaceous earth, silica sand, quartz, etc.), ■
Alumina, silicates containing 30wt.1% or more of SiO2 (e.g. amorphous or crystalline clay minerals, aluminosilicate compounds (including calcined products and hydrates), hot asbestos, zircon, fly ash) etc.), ■Oxides of Mg, Zn, Zr, and Ti, ■C a. , and sulfate of Ba,
■Li, Na, and Ca phosphates (including monohydrate and dihydrogen salts), ■Li, Na, and K benzoates, ■C
a, Ba. , Zn, and M n dephthalate, 11
DMg. Ca. , Ba, Zn, Cd, Pb, SrMn,
Titanate of Fe, Co, and N5, ■Ba. and pb
chromate, 0 carbon (e.g. carbon black, taraphite, etc.), ■Glass (e.g. glass powder, glass sheath, etc.), M g C O 3, ■ Fluorite, and @ZnS. Illustrated. Particularly preferred are spherical silica, silicone resin particles, anhydrous silicic acid, hydrated silicic acid,
Aluminum oxide, aluminum silicate (including calcined products, hydrates, etc.) monolithium phosphate, trilithium phosphate, sodium phosphate, calcium phosphate, barium sulfate, titanium oxide, ammonium, chloride, lithium fragrant, complexes of these compounds Salt (including permanent salts). Glass powder, clay (kaolin, bentonite 1
・, including white clay, etc.), talc, Geijojo, etc.6 As mentioned above, polyetherketones are known per se, and can be produced by methods known per se.6 The above polyetherketones The apparent melt viscosity is at temperature 3
500 to 10,000 voices, more preferably 1,000 to 5,000 voices under the conditions of 80° C. and an apparent shear rate of 1,000 sec-1, is preferred from the viewpoint of film formability and film properties.6 The unrolled material used in the present invention The intermediate film can be obtained by melting and forming the polyetherketone into a film by a conventionally known method and rapidly solidifying it, and is in a substantially non-oriented state. It is preferable to use an electrostatic loading method in the rapid solidification.

In the present invention, first, an unstretched film of polyetherketone is stretched in the longitudinal direction so that the birefringence becomes 0.02 or more and less than 0.07. This longitudinal stretching may be hereinafter referred to as pre-stretching. If the birefringence is less than 0.02, there will be no orientation effect, and the edge portions of the film will crystallize when heat setting is performed after transverse stretching, resulting in frequent breakage of the film during transverse stretching and/or heat setting. On the other hand, if the birefringence is 0.07 or more, the film will be frequently cut during longitudinal stretching again, impairing the stability of the process. The birefringence is preferably less than 0.06, more preferably less than 0.05.

The longitudinal stretching temperature in the first stage is 200°C above the glass transition temperature of the resin.
or below, and normally 145℃ to 200℃ is sufficient.
From the viewpoint of thickness unevenness, the temperature is preferably 180°C or lower, more preferably 170°C or lower.

In the present invention, the film that has been stretched in the previous stage is then stretched in the transverse direction so that the refractive index in the transverse direction is greater than the refractive index in the longitudinal direction and at a stretching ratio of 3.0 times or more. The lateral stretching ratio is preferably 3.2 times or more, and the lateral stretching temperature is 145
-200°C, more preferably 150-170°C. If the refractive index in the transverse direction is the same as or smaller than the refractive index in the longitudinal direction, the film will be cut frequently during longitudinal re-stretching, making it difficult to form a film. Furthermore, if the stretching ratio in the lateral direction is less than 3.0 times, the Young's modulus in the lateral direction will be low, and for example, when used for magnetic purposes, the end face of the tape may easily break.
Undesirable. Furthermore, thickness unevenness is also bad, which is not preferable.

In the present invention, the biaxially oriented film after transverse stretching is further heat-set at a temperature of -320°C or lower than the transverse stretching temperature and relaxed (contracted and relaxed) by 3 to 30% in the transverse direction (13 directions). , Then, fir stretching is performed again at a temperature below the above heat setting temperature.
More preferably, the temperature is 160 to 280°C, and the lateral relaxation is 4 to 20%. Furthermore, it is preferably 5 to 15%. The temperature for the second longitudinal stretching (hereinafter sometimes referred to as longitudinal re-stretching) is preferably 250°C or lower, more preferably 200°C. In addition, this temperature is 160℃ or more -F, furthermore 180℃ or more,
In particular, the magnification of 6-realignment stretching, which is preferably 190°C or higher, is 1.2.
~3.0 times, further 1.25 to 2.75 times, especially 1.3
It is preferable that it is ~2.7 times. This longitudinal re-stretching ratio is preferably selected from the above range, taking into account the physical properties of the obtained film, the ratio of the previous longitudinal stretching, etc.

After longitudinal re-stretching, heat setting may be performed as necessary.

Heat setting temperature is 200-360℃, even 230-350℃
C. Especially preferably 240 to 340'C. Heat setting time is 1
-100 seconds, more preferably 5-80 seconds, especially 10-60 seconds.

Thus, a longitudinally strengthened biaxially oriented polyetherketone film having a Young's modulus in the longitudinal direction of 600 kg/1-F and thickness unevenness in the longitudinal and transverse directions of 10% or less can be obtained in a stable process.

The thickness of the biaxially oriented polyetherketone film is 1 to 12
5 μm, more preferably 1 to 75 μm, particularly 1 to 50 μm.

Since the biaxially oriented polyetherketone film of the present invention has excellent thickness unevenness and is strengthened in the longitudinal direction, it is preferably used as a magnetic recording material and a condenser material.

(actual example) The present invention will be further explained below with reference to Examples.

In addition, various physical property values and characteristics included in the present invention were measured as follows.

(1) Thickness unevenness Measurements were made along the longitudinal and lateral directions of the axially oriented film using a continuous film thickness measuring device manufactured by Anritsu Denki, and the thickness was calculated using the following formula for a length of 1 m.

Maximum film thickness - Minimum film thickness Thickness unevenness = Film average thickness (2) Birefringence The refractive index is read in the vertical, horizontal, and thickness directions using an Atago Optical Appé refractometer, and the birefringence is measured in the vertical direction. Calculated from refractive index and lateral refractive index.

(3) Cut the Young's modulus film into sample rllomm, length 15 (self),
It was pulled using an Instron type universal tensile tester at a jack distance of 100 mm, a pulling speed of 10 II lm/min, and a char speed of 500 mm/min. It was determined based on the definition from the obtained load-elongation curve.

etherketone 380G) with 0.0% spherical silica particles.
After mixing 2 wt %, the mixture was melt-extruded at 380°C using an extruder and transferred to a casting drum L caster 1 maintained at a temperature of 80°C to obtain a non-oriented unstretched film.

This unstretched intermediate film was first longitudinally stretched using a ceramic-coated stretching roll under the conditions shown in Table 1, then transversely stretched, heat-set, longitudinally stretched again, and then further stretched at 300°C.
After heat setting, a longitudinally strengthened biaxially oriented film was obtained.

The thickness of this film was 12μ.

The Young's modulus and thickness unevenness of the obtained biaxially oriented film are shown in Table 1 along with the film forming conditions.

Examples 1 to 6 and Comparative Examples 1 to 4 Polyether cane (polyether 1/1 manufactured by Icl) As is clear from Table 1, according to the present invention, the strength in the longitudinal direction was increased under stable film forming conditions. A biaxially oriented film can be obtained, and the biaxially oriented film has excellent Young's modulus and good thickness unevenness.

(Effects of the Invention) According to the present invention, a biaxially oriented polyetherketone film having small thickness unevenness in the longitudinal and lateral directions and excellent strength in the longitudinal direction can be produced with excellent process stability.

Claims (1)

[Claims] The polyetherketone unstretched film has a birefringence of 0.02 or more and 0.02 or more at a temperature above the glass transition temperature and below 200°C.
07, and then transversely stretched at a stretching ratio of 3.0 times or more so that the refractive index in the transverse direction is greater than the refractive index in the longitudinal direction to form a biaxially oriented film. The biaxially oriented film is heat set at a temperature above the transverse stretching temperature and below 320°C, relaxed by 3 to 30% in the transverse direction, then longitudinally stretched again at a temperature below the above heat setting temperature, and then heated as necessary. Fixed, Young's modulus in the longitudinal direction is 600
kg/mm^2 or more and thickness unevenness in vertical and horizontal directions is 10%
A method for producing a longitudinally strengthened biaxially oriented polyetherketone film, characterized in that the film is as follows: