JPH01101335A - Biaxially oriented polyether ether ketone film - Google Patents

Abstract

PURPOSE:To obtain the titled film outstanding in surface flatness, slipperiness, traveling durability, electrical insulating characteristics, heat resistance etc., for use in e.g. heat-sensitive transfer, by incorporating polyether ether ketone with specified proportion of spherical silica particles of specific size. CONSTITUTION:The objective film can be obtained by dispersing (A) polyether ether ketone with (B) 0.01-3wt.% of spherical silica particles having the follow ing characteristics: 1. average size ... 0.05-4mum 2. size ratio (major axis/minor axis) ... 1.0-1.2 3. the value expressed by the relative standard deviation formu la {Di: diameter of circle equivalent to the area for each particle (mum); D: aver age value of Di's [i.e. D=(SIGMADi/n)]; n: number of particle} ... <=0.5. This film can also widely applied to e.g. metallic thin film-clad or coated magnetic record ing media.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a biaxially oriented polyether ether ketone film, more specifically, it contains specific spherical silica particles, has a flat surface, has smooth properties, and has good running durability.

This invention relates to a biaxial polyether ether ketone film that has excellent insulation properties and heat resistance.

[Prior Art] Biaxially oriented polyethylene terephthalate films have been widely used in industrial applications due to their excellent mechanical properties, thermal properties, chemical properties, etc. .

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 need for films with even better properties. The film has long-term heat resistance of Class E (long-term heat resistance = 125°C) to Class 8 (long-term heat resistance: 130°C).
), and when motor insulation is used as a wire coating material, there is a problem in that miniaturization of motors is restricted due to long-term heat resistance. Furthermore, when the above film is used for capacitor applications, 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, heat resistance 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, polyetheretherketone is known as a crystalline thermoplastic polymer that is tough and has excellent heat resistance (
Japanese Patent Publication No. 60-32642 and Japanese Patent Publication No. 61-10486), studies and proposals have been made to make this film into a film. ρ1 For example, JP-A-57-137116 discloses that polyetheretherketone is used in fields that take advantage of its heat resistance, such as insulating films for motors, insulating films for transformers,
The paper describes a method for manufacturing uniaxially oriented films using a rolling method, which is expected to be used in insulating films for capacitors, flexible printed circuit boards, etc.;

Talc, basic magnesium carbonate, alumina 1. Alumina hydrate + barium FfL acid, calcium sulfate.

It is explained that inorganic fillers such as mica powder, zinc white, titanium oxide, and carbon black may be added.

JP-A-58-63417 describes a method for producing an isotropic biaxially oriented polyetheretherketone film.

JP-A No. 60-93625 describes a polyetheretherketone film for perpendicular magnetization that is biaxially oriented by a rolling method; The stress at 5% elongation in both directions is t3kr/1
il12 or more, initial elastic modulus in at least one direction is 600
kg/rm' and a heat shrinkage rate of 4% or less in the longitudinal direction and perpendicular direction at 180 °C is described. It is also explained that lubricants such as titanium dioxide matting, particulate silica, and china clay may be included in the polymer.

JP-A-6O-t89421 discloses a polyetherketone (or polyetheretherketone) containing inorganic particles, having a surface roughness Ra of 0.008 to 0.090 and a dynamic traction coefficient μd of 0. 12 to 0.50 is described, and this no I! Fine particles include non-alpha oxides such as magnesium oxide, zinc oxide, magnesium carbonate, magnesium phosphate, calcium sulfate, barium sulfate, aluminum oxide, silicon dioxide, titanium oxide, kaolin, and diatomaceous earth.

It is explained that inorganic salts, aluminosilicates, carbon black, etc. can be mentioned.

JP-A-61-37418 discloses that 100 parts by weight of polyetheretherketone contains 0.01 to 10 parts by weight of an inorganic filler.
An easily slippery thermoplastic polyether ether ketone film is described, which is prepared from a biaxially oriented film formed from a composition containing 1 part by weight of talc as the inorganic filler.

One or more types of silica, kaolin, calcined kaolin, mica, aerosil, thyroid, calcium carbonate, potassium titanate fibers, etc. are appropriately selected and used, but those with a fine particle size of 5 μm or less in average particle size are particularly preferred. It is explained. However, according to the research results of the present inventors, these biaxially oriented polyetheretherketone films have voids around the inorganic particles in the film, and the running durability, insulation defect abnormality rate, and insulation It became clear that there were issues that needed to be improved, such as destruction. It was also revealed that inorganic particles were poorly dispersed in the film.

[Purpose of the Invention] An object of the present invention is to provide a biaxially oriented polyetheretherketone film that has a flat surface, excellent slipperiness, running durability, insulation properties, etc., and excellent heat resistance.

Another object of the present invention is to provide biaxially oriented polyether ether which has a large number of fine protrusions derived from spherical silica particles on the film surface, and has a flat surface and is excellent in slipperiness, running durability, insulation properties, etc. Our goal is to provide Getton film.

Further objects and advantages of the present invention will become apparent from the description below.

[! @Ming Structure/Effects] According to the present invention, the above objects and advantages of the present invention are as follows: Firstly, the average particle size is 0.05
~4 μm and particle size ratio (major axis/breadth axis) of 1.0 to 1
．． This is achieved by using a biaxially oriented polyetheretherketone film containing 0.01 to 3% by weight of spherical silica particles of No. 2 dispersed therein.

The polyetheretherketone in the present invention is a polymer consisting of units and other constituent units. Examples of other structural units include the following. In the above structural unit, A is a direct bond, oxygen, -8O□-, -CO-, or a divalent lower aliphatic hydrocarbon group, and Q and Q' may be the same or different and -CO - or 1'SO2-, and n is 0 or 1. These polymers are
It is described in Japanese Patent Publication No. 642, Japanese Patent Publication No. 61-10486, Japanese Patent Application Laid-Open No. 57-137116, etc.

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

As mentioned above, polyetheretherketone is known per se and can be produced by a method known per se.

The above-mentioned polyether ether ketone has an apparent melt viscosity of 500 to 10,000 voids, and even 10,000 voids under the conditions of a temperature of 380°C and an apparent shear rate of 200 Sec'.
Those in the range of 0 voids to 5000 voids are preferred from the viewpoint of film formability and film properties.

The biaxially oriented polyetheretherketone film of the present invention has many fine protrusions on its surface.

According to the invention, these large numbers of fine protrusions originate from a large number of spherical silica particles dispersed and contained in the polymer.

Polyetheretherketone containing dispersed spherical silica particles can be produced, for example, by adding spherical silica particles during the reaction to form polyetheretherketone. It is also possible to form a film by triblending an unadded polymer and spherical silica particle powder. Either method may be used, but the latter is preferred.

In the present invention, the spherical silica particles dispersed and contained in polyetheretherketone have an average particle size of 0.05 to 4 μm.
These are silica particles having a particle size ratio (major axis/breadth axis) of 1.0 to 1°2. These spherical silica particles have individual shapes that are extremely close to true spheres, and the silica particles conventionally known as lubricants are ultrafine lump particles of about 10 mm, or aggregates of about 0.5 μm. Aggregates (
The average particle size of the 0 spherical silica particles, which are characterized by being significantly different from those forming aggregated particles (°), is preferably 0.
．． The average particle size is 10 to 3 μm, more preferably 0.2 to 2 μm. If the average particle size is less than 0.05 μm, the effect of improving slipperiness and abrasion resistance is insufficient, which is not preferable. If it exceeds this, the film surface will become too rough, which is undesirable, and the particle size ratio of the spherical silica particles is preferably 1.0 to 1.15. More preferably, it is 1.0 to 1.1.

Further, it is preferable that the spherical silica particles have a sharp particle size distribution, and the relative standard deviation representing the steepness of the distribution is 0.
It is preferably 5 or less, more preferably 0.4 or less, particularly 0.3 or less.

This relative standard deviation is expressed by the following formula.

Relative standard deviation = where, Di; area equivalent diameter of individual particle (μm) D =
Average diameter equivalent to sum of surface areas (=(Σ Di)/n) (μm) i=1 n: represents the number of particles measured.

Here, the major axis and minor axis of the spherical silica particles are determined from an image magnified 10,000 to 30,000 times with a scanning electron microscope after depositing a metal layer on the particle surface, and the average particle size is 1 Find the particle size ratio using the following formula.

When using spherical silica particles having an average particle diameter = sum of area equivalent diameters of measurement particles / number particle diameter ratio of measurement particles = average major axis of silica particles / average minor axis relative standard deviation of the particles of 0.5 or less, Since the particles are spherical and have an extremely steep particle size distribution, the height of the protrusions on the film surface is extremely uniform, and each protrusion on the film surface has a very small void around the lubricant, so the protrusion shape is extremely uniform. The protrusions are sharp, and therefore, even with the same number of protrusions, the slipperiness is extremely good.

Spherical silica particles can be produced by any method that meets the above conditions.
There are no other limitations.

For example, spherical silica particles are made of ethyl orthosilicate [Si
(OC2Hs) directly] from the hydrolysis of hydrated silica [3
i (OH)
0-3t Mi] can be produced by three-dimensional growth (Journal of the Chemical Society of Japan' 81.110.9゜P, 1503
).

S i (OC2H5') a +4820→S i
(OH) a +4C2-H! 10H=S i -OH
+HO-3i = -=Si OSi=+H20 In the present invention, the amount of spherical silica particles added needs to be 0.01 to 3.0% by weight relative to polyetheretherketone, preferably 0.01 to 1% by weight. 0.0% by weight, more preferably 0.05 to 0.75% by weight.

If the amount added is less than 0.01% by weight, the effect of improving slipperiness and abrasion resistance will be insufficient, while if it exceeds 3.0% by weight, surface flatness will deteriorate, which is not preferable.

In the present invention, the biaxially oriented polyetheretherketone film has extremely small voids compared to conventional films, and the reason why the voids are small is because of the good affinity of the spherical silica particles to polyetheretherketone. Furthermore, since the particles themselves are extremely close to true spheres, it is presumed that the stress around the lubricant propagates evenly during stretching, and stress does not concentrate on a part of the interface between the polyetheretherketone and the lubricant.

The biaxially oriented polyetheretherketone film of the present invention has uniform uneven surface characteristics, excellent slipperiness, heat resistance, and abrasion resistance, and is characterized in that it generates significantly less scratches and white powder.

This biaxially oriented polyetheretherketone film can be used for various purposes by taking advantage of these activities.

Generally, polyetheretherketone and inert particles (lubricant) have no affinity. For this reason, when an unstretched film of melt-formed polyetheretherketone is biaxially stretched, peeling occurs at the boundary between the fine particles and polyetheretherketone, and voids are usually formed around the fine particles. The larger the particle is, the more spherical the particle is, and the more difficult the particle is to deform as a single particle.
Furthermore, when stretching an unstretched film, the stretching area ratio tends to increase as the stretching area ratio increases and as the stretching process is carried out at a lower temperature. The larger the void, the more gradual the shape of the protrusion, which increases the coefficient of friction.
At the same time, voids in the biaxially oriented polyether ether ketone film that occur during repeated use may fall off, reducing durability and causing the generation of shavings.

As described above, in the case of conventional inorganic inert lubricants, the amount of voids around the lubricant is quite large, and in high-strength polyetheretherketone films, these voids become even larger, resulting in problems such as the calendering process of magnetic tape, etc. The machining resistance becomes poor during the machining process. It also leads to a decrease in dielectric breakdown voltage in capacitors.

As mentioned above, the spherical silica particles used in the present invention have a high affinity with the polyetheretherketone substrate, and therefore voids are less likely to occur around the particles. When using the above-mentioned spherical silica particles, the frequency of occurrence of voids can be suppressed to a low level. Therefore, according to the present invention, spherical silica particles are used as relatively large particles, and at the same time, the frequency of occurrence of voids is reduced. It is possible to provide a film with excellent runnability, abrasion resistance, fatigue resistance, dielectric breakdown voltage, transparency, etc. while having the advantage of using two types of particles by using relatively small particles with a small amount of particles. became clear.

In other words, such a biaxially oriented polyether ether getone film has (I) in the polyether ether ketone having an average particle size of 0.2 to 4 μm and a particle size ratio (major axis/breadth axis) of 1.0 to 4 μm. 1.2 spherical silica particles with 0
．． 005 to 3% by weight, and (II) inert fine particles having an average particle size of 0.05 to 3 μm and whose average particle size is smaller than the average particle size of spherical silica particles. This is a biaxially oriented polyetheretherketone film containing 2% by weight of dispersed polyetheretherketone.

The polyetherethergeddon and spherical silica particles (I) are as described above. However, as the spherical silica particles, relatively large particles with an average particle diameter of 0.2 to 4 μm are used in this case.

As the inert fine particles (I[) whose average particle diameter is smaller than that of the spherical silica particles, those which are inert and insoluble in polyether ether getone and solid at room temperature are used. These may be externally added particles or internally generated particles, and may also be, for example, metal salts of organic acids or inorganic substances. Preferred inert fine particles include (1) calcium carbonate;

■Silicon dioxide (including hydrates, diatomaceous earth, quartz, etc.), ■Alumina, ■Gate salts containing 30% by weight or more of 810□ (e.g. amorphous or crystalline clay minerals) ,
Aluminosilicate compounds (including fired products and hydrated products),
Warm asbestos, zircon, flyadzhu, etc.), ■Mg, Zn
, Zr and Ti oxides, ■ Ca and Ba sulfates, ■
Phosphates of Li, Na and Ca (including monohydrogen salts and dihydrogen salts), ■benzoates of l, i, Na and K, ■Ca.

Terephthalates of Ba, Zn and Mn, [phase] Mg.

Ca, Ba, Zn, Cd, Pb, Sr, Mn.

titanates of Fe, Co and Ni, chromates of OBa and pb, @carbon (e.g. carbon black, graphite, etc.), ■glass (e.g. glass powder, glass peas, etc.), 0MgCO3, ■fluorite, and @Z An example is nS. Particularly preferred are anhydrous silicic acid, hydrated silicic acid, aluminum oxide, aluminum silicate (including fired products, hydrates, etc.), monolithium monophosphate, and trilithium phosphate.

Sodium phosphate, calcium phosphate, barium sulfate.

Titanium oxide, lithium benzoate, double salts of these compounds (including hydrates), glass powder, clay (including kaolin, bentonite, clay, etc.), talc.

Examples include diatoms. Such inert fine particles (I[)
Among these, externally added particles are particularly preferred.

The spherical silica particles (I) have an average particle size of 0.2 to 4 μm. They preferably have an average particle size of 0.3 to 2 μm, particularly preferably 0.5 to 1.5 μm.

In addition, the inert particles (I[) have an average particle diameter of 0.05 to 3 μm, but are used in combination with an average particle diameter smaller than that of the spherical silica particles (I).

Inert fine particles (If) are preferably 0.10 to 2.0μ
It has an average particle size of m, more preferably 0.20 to 1.5 μm.

The content of inert fine particles (IF) is o, oos ~ 3% by weight based on polyetheretherketone, but 0.0
1 to 2% by weight, even 0.02 to 1.0% by weight, especially 0
．． 05 to 0.75% by weight is preferred. On the other hand, the content of linear silica particles (I) is o, oos ~ 3% by weight based on polyetheretherketone, but it is 0.01 ~ 2% by weight.
, and even 0.02 to 1. OII amount%, especially 0.05-0
．． 75% by weight is preferred.

If the content of inert fine particles ([) or spherical silica particles (I) is too small, the synergistic effect of using two types of particles, large and small, cannot be obtained, resulting in poor running performance, wear resistance, fatigue resistance, crushability, This is undesirable because properties such as edge alignment deteriorate, but if the content of inert particles (n) is too large, voids due to small particles in the polymer tend to occur more frequently, resulting in poor wear resistance. properties, fatigue resistance, crushability, insulation voltage, transparency, etc.

Furthermore, if the content of the spherical silica particles (I) is too large, the surface of the film becomes too rough and, for example, the electromagnetic conversion characteristics of a magnetic tape deteriorate, which is not preferable.

In producing the biaxially oriented film of the present invention, in order to intimately mix spherical silica particles or inert fine particles therewith with polyetheretherketone, these fine particles are polymerized before or during the polymerization of polyetheretherketone. It may be sufficiently kneaded with the polyether ether ketone in a pot, in an extruder when pelletizing after completion of polymerization, or in an extruder when melt extruding into a sheet.

The biaxially oriented polyetheretherketone film of the present invention can be produced according to conventional methods for producing biaxially oriented films.For example, the biaxially oriented polyetheretherketone film containing spherical silica particles is melt-formed into a film. It is produced by forming an amorphous unstretched film, then stretching the unstretched film in the two-wheel direction, heat-setting it, and subjecting it to relaxation heat treatment if necessary. At this time, the film surface properties vary depending on the particle size, amount, etc. of the spherical silica particles, and also depending on the stretching conditions, so they are appropriately selected from conventional stretching conditions. In addition, the density, heat shrinkage rate, etc. change depending on the temperature, magnification, speed, etc. during stretching and heat treatment, so the conditions that satisfy these characteristics at the same time are determined.
For example, the longitudinal stretching temperature (T1) is (Tg-10) to (7
g+45)'C range (however, Tg: glass transition temperature of polyetheretherketone) to the second stretching temperature (
For example, the lateral stretching temperature: T2) is (Tt-N5) ~ (T
It is preferable to select from the range of 1+40)'C, and the stretching ratio is from a range where the uniaxial stretching ratio is 1.5 or more, especially 2.5 times or more, and the area magnification is 4 times or more, especially 6 times or more. Furthermore, the heat setting temperature is preferably 200℃.
It is preferable to select from the range of ~350°C, more preferably 220~255°C, and the heat setting time is, for example, 1~20 seconds.

The thickness of the biaxially oriented film is 1 to 250 μm, and even 1 μm.
~125 μm, particularly 1-75 μm is preferred.

The biaxially oriented polyether ether gent film of the present invention has uniform uneven surface characteristics, excellent slipperiness, heat resistance, and abrasion resistance, and is characterized in that it generates significantly less scratches, white powder, and the like.

Taking advantage of these properties, this biaxially oriented polyetheretherketone film can be used in a wide variety of applications.For example, when used as electrical insulation materials, motor insulation, and wire coatings, it has excellent heat resistance and processing properties. You can obtain gender etc. Furthermore, when used in capacitor applications, it is possible to obtain high-quality capacitors that can be used at high temperatures due to its low coefficient of friction, excellent winding properties, low crushing load, and excellent heat resistance. In addition, when used in FPC (flexible printed circuit) applications, FPC has excellent solder resistance.
It is possible to obtain In addition, when used as a base film for magnetic recording such as video, audio, and computers, it has excellent electromagnetic conversion characteristics, slipperiness,
Driving durability etc. can be obtained. In particular, it is suitable as a base film for vacuum evaporation or sputtering, which is formed by applying a metal thin film to a base film, due to its heat resistance.

Biaxially oriented polyether ether getone films are particularly preferred for use in electrical disconnection, capacitors, FPCs, and metal thin film magnetic recording media, but are also widely applicable as films for coated magnetic recording media, vapor deposition, thermal transfer, etc. can do.

[Example] The present invention will be further explained below with reference to Examples.

Note that various physical property values and characteristics in the present invention were measured as follows.

(1) Particle size There are the following conditions for particle size measurement.

1) When calculating the average particle size, particle size ratio, etc. from silica powder 2) When calculating the average particle size, particle size ratio, etc. of silica particles in a film 1) When using silica powder: Electron microscope sample stage Silica powder was scattered on the top so that the individual particles did not overlap as much as possible, and a gold thin film was deposited on the surface using a gold sputtering device to a thickness of 200 to 300 mm, and a thickness of 10,000 to 300 mm was measured using a scanning electron microscope. 30000
Observe at double magnification and use Luzex 50 manufactured by Nippon Regulator ■.
at least 100 particle long diameters (Dli) at 0;
Determine the short axis (DSi>) and the area circle equivalent diameter (Di).Then, using these number average values expressed by the following formula, calculate the long axis (DI), short axis (Ds), and average particle diameter (D ).

n
nDI=(Σ D It) /n, D s = (Σ
DSi) / n1 = 1 i = 1 D = (Σ D i ) / n 1 = 1 2) In the case of silica particles in a film: Fix a small piece of sample film on a sample stage for a scanning electron Mm mirror, and place it on a JEOL sputtering equipment (JFC-110
The ion etching process is performed on the film surface under the following conditions using a 0 type ion sputtering device (0 type ion sputtering device). For the 0 condition, the sample is placed in a Pel jar, the degree of vacuum is raised to a vacuum state of approximately 10-" Torr, and the voltage is 0. Ion etching is carried out for about 10 minutes at .25 KV and a current of 1.25 mA.Furthermore, gold sputtering is applied to the film surface using the same equipment, and the film is etched using a scanning electron microscope with an etching temperature of 10,000 to 3,000, for example.
Observe at 0x magnification and use Luzesku 5 manufactured by Nippon Regulator.
the long diameter (Dli) of at least 100 particles at 00;
The minor axis (Dsi) and the area circle equivalent diameter (Di) are determined. The following steps are carried out in the same manner as in 1) above.

(2) Film surface roughness (Ra) This is the value defined in JIS-80601 as the center line average roughness (Ra). ). The measurement conditions are as follows.

(a) Stylus tip radius: 2 μm (b) Measurement pressure: 30 g (C) Cutoff: 0.25 mm (d) II
J constant length: 0.5oun(e) How to summarize the data - Measure the sample 5 times and set the largest value as 1
The average value of the remaining four data is rounded off to the fourth decimal place and displayed to the third decimal place.

(3 void ratio) Expose the area around the lubricant in the film (surface) according to the method (11-2) above, measure the long diameter of at least 50 solid particles and the long diameter of the void, and calculate the following formula: Long diameter void ratio of the void = □ Expressed as the number average value of the void ratio determined by the major axis of solid particles.

(4) Coefficient of friction of film (μk) In an environment with a temperature of 20°C and a humidity of 60%, a film cut to a width of 1/2 inch is held on a fixed rod (surface roughness 0.3 μm) at an angle θ = 1! +2
/180π radians (152°) and 20 per minute
Move (RI rub) at a speed of 0 aa.

The outlet tension (Tt:g) when the tension controller is adjusted so that the inlet tension T1 is 35g.
) is detected by an outlet tension detector after the film has traveled 90 m, and the running wear coefficient μk is calculated using the following formula.

μ = (2,303/θ) 1oiJ (Tz /
T1) = 0.868 +01J (T2 /35) (5)
Haze (cloudiness) According to JIS-K 674, the haze of the film is determined using an integrating sphere HTR meter manufactured by Nippon Seimitsu Kogaku Co., Ltd.

(6) Dielectric breakdown voltage and dielectric breakdown abnormality rate Dielectric breakdown voltage is measured by the method shown in J I 5-C-2318.

The average value of n=100 is adopted, and the ratio (%) of those exhibiting a value of 1/3 or less of this average value is defined as the dielectric breakdown abnormality rate.

(7) Evaluation of element end face irregularities and element end face shape after flattening A 10μ film is vapor-deposited with aluminum and slit into 20mm widths, and wound around a core with an outer diameter of 3rIm at a tension of 40g.
An element was wound to a length of 4 m at a winding speed of 30 windings/sec. Regarding the unevenness of the element end faces, those whose end faces were all perfectly aligned were marked as ○, and some of them were slightly irregular. Δ
, those that cannot be used are marked with an ×.

When the element is flattened by pressing, the end face shape after flattening is evaluated as ○ if the film layers are flattened in a straight line with no gaps, and ○ if the film layers are flattened in a straight line with no gaps, and ○ if there is a slight gap in some parts and there is no problem in practical use. If there is no film, mark it as △, and if it is unusable due to uneven crushing and gaps between the film layers, mark it as X.

(8) Comprehensive evaluation of capacitors Comprehensive evaluation of electrical properties such as crushability, single-turnability, vapor deposition processability, dielectric breakdown voltage, and dielectric breakdown abnormality rate. Those with some inferiority but no practical problems are marked as ○, those with practical problems are marked as △, and those that cannot withstand use are marked as ×.

(9) The agglomerated film of lubricant is magnified 20 times under polarized light, a polarizing plate is crossed at right angles, and the number of agglomerated lubricants of 25μ or more that shines in the dark field is measured for evaluation. The measurement area is 10-, and the number of pieces per 1a11 is 0°10-30.
△

×30 or more.

shall be.

Examples 1 to 7 Spherical silica particles and inert particles were mixed with polyetheretherketone (polyetheretherketone 380G manufactured by IC1) in the proportions shown in Table 1, and after blending, extrusion was carried out at 380°C with an extruder to give 80% A 90 μm unstretched film was created by casting onto a casting drum maintained at a temperature of 160° C. This was stretched 2.5 times in the machine direction at 160° C., further fed to a tenter, and stretched 3 times in the transverse direction at 160° C.
．． It was stretched 5 times and heat set at 250°C for 30 seconds.

The properties of these films are shown in Table-1.

Comparative Examples 1 to 3 Comparative Examples 1 to 3 The same polymer as in Example 1 was used, but the lubricant was changed to one shown in Table 1, and the same procedure as in Example 1 was conducted. The results are shown in Table-1.

From the results shown in Table 1, it can be seen that the film of the present invention has a flat surface, a small coefficient of friction in repeated cycles, and excellent lubricity. Furthermore, the film of the present invention has less agglomeration of the lubricant, and is found to be very excellent as a base for a capacitor.

Procedural amendment January 1st, 1989

Claims (1)

[Claims] 1. In polyetheretherketone, the average particle size is 0.
05 to 4 μm and the particle size ratio (major axis/breadth axis) is 1.0
A biaxially oriented polyetheretherketone film containing 0.01 to 3% by weight of spherical silica particles having a particle diameter of 1.2% by weight. 2. The biaxially oriented polyether ether Kent film according to claim 1, wherein the relative standard deviation of the spherical silica particles expressed by the following formula is 0.5 or less. Relative standard deviation = ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Here, Di: Area circle equivalent diameter of each particle (μm) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ n: Represents the number of particles. 3. In polyetheretherketone, (I) the average particle size is 0.2 to 4 μm and the particle size ratio (
(II) 0.005 to 3% by weight of spherical silica particles having a length (major axis/breadth axis) of 1.0 to 1.2; and (II) an average particle size of 0.05 to 3 μ; A biaxially oriented polyetheretherketone film containing 0.005 to 3% by weight of inert fine particles whose particle size is smaller than the average particle size of spherical silica particles.