JPH0613614B2 - Biaxially oriented polyetheretherketone film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a biaxially oriented polyetheretherketone film, more specifically containing specific spherical silica particles, and having a flat surface, slipperiness, running durability, and insulation. The present invention relates to a biaxially oriented polyetheretherketone film having excellent properties and heat resistance.

[Prior Art] Conventionally, a biaxially oriented polyethylene terephthalate film has been widely used for industrial applications because of its excellent mechanical properties, electrical properties, heat resistance, chemical resistance and the like.

However, in recent years, the required properties of the film have been increased depending on the application, and the properties of the biaxially oriented polyethylene terephthalate film are also limited. Therefore, a film having more excellent properties is required. For example, biaxially oriented polyethylene terephthalate film has long-term heat resistance of Class E (long-term heat resistance temperature: 125 ° C) to Class B (the same: 130 ° C), and when used as a material for motor insulation and wire coating, From this point, there is a problem that miniaturization of the motor is limited. Also, when the above film is used for capacitors, the dielectric loss tangent increases from around 85 ° C,
It brings about the limitation of operating temperature. Furthermore, when the above film is used as a flexible printed circuit board, solder heat resistance becomes a problem, and its development is limited. Therefore, there is a demand for a film having more excellent heat resistance.

By the way, polyether ether ketone is known as a crystalline thermoplastic polymer that is tough and has excellent heat resistance (Japanese Patent Publication No. 32642, Japanese Patent Publication No. 61-10486), and investigations and proposals have been made for this film. . For example, in Japanese Patent Laid-Open No. 57-137116, polyetheretherketone is used in applications where heat resistance is utilized, that is, insulating films for motors, insulating films for transformers,
A method for producing a uniaxially oriented film by a rolling method is described as expected to be applied to insulating films for capacitors, flexible printed circuit boards, etc., and depending on the application, calcium carbonate, fine particle silicate, talc, etc. , Basic magnesium carbonate, alumina, hydrated alumina, barium sulfate, calcium sulfate, mica powder,
It is described that an inorganic filler such as 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-60-93625 describes a polyetheretherketone film for perpendicular magnetization which is biaxially oriented by a rolling method.

JP-A-60-187928 discloses that the stress at 5% elongation in the length direction and the direction perpendicular thereto is 13 kg / mm ² or more, the initial elastic modulus in at least one direction is 600 kg / mm ² or more, and 18
A magnetic recording material based on a biaxially oriented polyetheretherketone (or polyetheretherketone) film having a thermal shrinkage at 0 ° C. in the lengthwise direction and in the direction perpendicular thereto of 4% or less is described, and in a polymer. It is described that a lubricant such as a titanium dioxide matting agent, fine particle silica, and china clay may be contained.

Japanese Unexamined Patent Publication No. 60-189421 discloses a biaxial orientation which is made of polyetherketone (or polyetheretherketone) containing inorganic particles and has a surface roughness Ra of 0.008 to 0.090 and a dynamic friction coefficient μd of 0.12 to 0.50. As the inorganic fine particles, magnesium oxide, zinc oxide, magnesium carbonate, magnesium phosphate, calcium sulfate, barium sulfate, aluminum oxide, silicon dioxide, titanium oxide, kaolin, diatomaceous earth and other inorganic oxides, inorganic salts, It is described that examples thereof include aminosilicates and carbon black.

JP-A-61-37418 discloses that a composition prepared by mixing 100 parts by weight of polyether ether ketone with 0.01 to 10 parts by weight of an inorganic filler to form a biaxially oriented slippery thermoplastic polyether ether. Ketone film is described, and this inorganic filler is talc, silica, kaolin, calcined kaolin,
One or more kinds of mica, aerosil, siloid, calcium carbonate, potassium titanate fiber, etc. are appropriately selected and used, and it is described that fine particles having an average particle diameter of 5 μ or less are particularly preferable.

However, according to the research results of the present inventors, in these biaxially oriented polyetheretherketone films, voids are generated around the inorganic particles in the film, and the running durability, the insulation defect abnormality rate, and the dielectric breakdown occur. It became clear that there are some issues that need to be improved. It was also found that the inorganic particles were poorly dispersed in the film.

[Object of the Invention] An object of the present invention is to provide a biaxially oriented polyetheretherketone film which has a flat surface and is excellent in slipperiness, running durability, insulation properties and the like, and is also excellent in heat resistance.

Another object of the present invention is a biaxially oriented polyether ether which has a large number of fine projections derived from spherical silica particles on the surface of the film and has a flat surface and is excellent in slipperiness, running durability, insulation properties and the like. To provide a ketone film.

Further objects and advantages of the present invention will be apparent from the following description.

According to the present invention, the above objects and advantages of the present invention are as follows.
The average particle size is 0.05 to 4 in polyetheretherketone.
This is achieved by a biaxially oriented polyetheretherketone film in which 0.01 to 3% by weight of spherical silica particles having a particle size ratio (major axis / minor axis) of 1.0 to 1.2 are dispersed and contained.

The polyether ether ketone in the present invention is a constitutional unit. Is a polymer alone or consisting of this unit and other constitutional units. As other structural units, for example, Etc. In the above structural unit, A is a direct bond, oxygen, —SO ₂ —, —CO— or a divalent lower aliphatic hydrocarbon group, and Q and Q ′ may be the same or different. CO- or -SO ₂ - and is, n is 0
Or 1. These polymers are described in JP-B-60-32642, JP-B-61-10486 and JP-A-57-137116.

Polyether ether ketone may be blended with a resin such as polyarylene polyether, polysulfone, polyarylate, polyester or polycarbonate for the purpose of improving fluidity, and may also be blended with stabilizers, antioxidants, ultraviolet absorbers and the like. Such additives may be contained.

The polyether ether ketones are known per se and can be produced by methods known per se, as described above.

The above polyether ether ketone has an apparent melt viscosity of 380 ° C. and an apparent shear rate of 1000 sec ⁻¹ , 50
Those in the range of 0 poise to 10000 poise, more preferably 1000 poise to 5000 poise are preferable from the viewpoint of film-forming property and film property.

The biaxially oriented polyether ether ketone film of the present invention has a large number of fine projections on the surface of the film.
The large number of fine projections derives from the large number of spherical silica particles contained according to the invention dispersed in the polymer.

The polyether ether ketone containing spherical silica particles dispersed therein can be produced, for example, by adding the spherical silica particles during the reaction for forming the polyether ether ketone. It is also possible to dry-blend an unadded polymer and spherical silica particle powder to form a film. Either method may be used, but the latter is preferable.

In the present invention, the spherical silica particles dispersedly contained in the polyether ether ketone are silica particles having an average particle size of 0.05 to 4 μm and a particle size ratio (major axis / minor axis) of 1.0 to 1.2. These spherical silica particles have a spherical shape that is extremely close to a true sphere, and silica particles that have been known as lubricants are ultra-fine aggregate particles of about 10 mμm or aggregates of about 0.5 μm. It is characterized in that it is remarkably different from that of forming a substance (aggregated particles). The average particle size of the spherical silica particles is preferably 0.10 to 3 μm, more preferably 0.2 to 2 μm. This average particle size is 0.05μ
If it is less than m, the effect of improving slipperiness and abrasion resistance is insufficient, which is not preferable. If the average particle size exceeds 4 μm, the film surface is too rough, which is not preferable. 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, the spherical silica particles preferably have a sharp particle size distribution, and the relative standard deviation representing the steepness of the distribution is 0.5.
It is preferably 0.4 or less, more preferably 0.4 or less, and particularly preferably 0.3 or less.

This relative standard deviation is expressed by the following equation.

Here, Di: area circle equivalent diameter of each particle (μm): average value of area circle equivalent diameter n: represents the number of particles measured.

Here, the major axis, the minor axis, and the equivalent circle diameter of the spherical silica particles are obtained 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 diameter, The particle size ratio is calculated by the following formula.

Average particle size = sum of area circle equivalent diameters of measured particles / number of measured particles particle diameter ratio = average major axis of silica particles / average minor axis of the particles When spherical silica particles having a relative standard deviation of 0.5 or less are used,
Since the particles are spherical and the particle size distribution is extremely steep, the height of the projections on the film surface becomes extremely uniform, and furthermore, the projections on the film surface have very small projection voids because the voids around the lubricant are small. It is sharp, and therefore the slipperiness is extremely good even with the same number of protrusions.

Spherical silica particles, if the above conditions are satisfied, the production method thereof,
There is no other limitation. For example, spherical silica particles can be made from ethyl orthosilicate [Si (OC ₂ H ₅ ).
₄ ] is hydrolyzed to form hydrous silica [Si (OH) ₄ ] monodisperse spheres, and the hydrous silica monodisperse spheres are dehydrated to three-dimensionally bond silica bonds [≡Si-O-Si≡]. It can be manufactured by growing it (Journal of the Chemical Society of Japan '81, No. 9,
P. 1503).

Si (OC ₂ H ₅ ) ₄ + 4H ₂ O → Si (OH) ₄ + 4C ₂ H ₅ OH ≡Si-OH + HO-Si≡ → ≡Si-O-Si≡ + H ₂ O In the present invention, the addition amount of spherical silica particles is , It is necessary to be 0.01 to 3.0% by weight, preferably 0.01 to 1.0% by weight, and more preferably polyether ether ketone.
It is 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 becomes insufficient, while
If it exceeds 3.0% by weight, the surface flatness is deteriorated, which is not preferable.

The biaxially oriented polyetheretherketone film in the present invention is a film having extremely small voids as compared with the conventional one, and the reason for this small void is that the spherical silica particles have good affinity for polyetheretherketone. Moreover, since the particles themselves are extremely close to a true sphere, it is speculated that the stress around the lubricant is evenly propagated during stretching and the stress is not concentrated on a part of the interface between the polyether ether ketone and the lubricant.

The biaxially oriented polyetheretherketone film of the present invention is characterized in that it has uniform uneven surface characteristics, excellent slipperiness, heat resistance and abrasion resistance, and the generation of scratches, white powder, etc. is extremely small. This biaxially oriented polyetheretherketone film can be used for various purposes by utilizing these activities.

Generally, there is no affinity between polyether ether ketone and inert particles (lubricant). Therefore, when biaxially stretching the unstretched polyetheretherketone film that has been melt-formed,
It is usual that peeling occurs at the boundary between the fine particles and the polyether ether ketone, and a void is formed around the fine particles. This void is, the larger the fine particles, the closer the shape is to a sphere, the more difficult the fine particles are to be deformed by a single particle, and the larger the stretching area ratio when stretching the unstretched flume, and the lower the temperature is. Tends to grow. The larger the void, the more gradually the shape of the protrusion becomes so that the friction coefficient becomes high, and with that, the void of the biaxially oriented polyetheretherketone film that occurs during repeated use comes off,
It reduces durability and causes shavings.

As described above, in the case of the conventional inorganic inert lubricant, the void amount around the lubricant is considerably large, and in the high-strength polyetheretherketone film, the void becomes larger, and as a result, the calendering step of the magnetic tape, etc. The abrasion resistance becomes poor in the processing process. In addition, in the case of capacitors, this leads to a decrease in dielectric breakdown voltage.

The spherical silica particles used in the present invention have a high affinity with the polyetheretherketone substrate as described above, and therefore the occurrence of voids around the particles is low. Therefore, the frequency of generating voids that generally become larger as the particles become larger, since it can be suppressed small when using the spherical silica particles, according to the present invention, using spherical silica particles as relatively large particles, Along with that, particles with a relatively small proportion of voids are used in combination, and while having the advantage of using two kinds of particles, it is possible to improve running property, wear resistance, fatigue resistance, breakdown voltage and transparency. It has been revealed that it can provide an excellent film.

That is, the biaxially oriented polyetheretherketone film is a spherical silica particle having (I) an average particle diameter of 0.2 to 4 .mu.m and a particle diameter ratio (major axis / minor axis) of 1.0 to 1.2 in the polyetheretherketone. To 0.005 to 3
%, And (II) 0.005 to 2% by weight of inactive fine particles having an average particle size of 0.05 to 3 μm and having an average particle size smaller than the average particle size of spherical silica particles. It is a biaxially oriented polyetheretherketone film.

The polyether ether ketone and the spherical silica particles (I) are as described above. However, as the spherical silica particles, relatively large particles having an average particle size of 0.2 to 4 μm are used in this case.

As the inert fine particles (II) having an average particle size smaller than that of the spherical silica particles, those which are inert and insoluble in polyetheretherketone and which are solid at room temperature are used. These may be externally added particles or internally generated particles. Further, for example, it may be a metal salt of an organic acid or an inorganic substance. Preferred inert fine particles include calcium carbonate, silicon dioxide (hydrate, diatomaceous earth, silica sand,
(Including quartz), alumina, SiO ₂ content 30% by weight
Silicates contained above (for example, amorphous or crystalline clay minerals, aluminosilicate compounds (including calcined products and hydrates), warm asbestos, zircon, fly ash, etc., M
g, Zn, Zr and Ti oxides, Ca and Ba sulfates, Li, Na and Ca phosphates (monohydrogen salts and 2
Hydrogen salt), benzoates of Li, Na and K,
Ca, Ba, Zn and Mn terephthalates, Mg,
Ca, Ba, Zn, Cd, Pb, Sr, Mn, Fe, C
o and Ni titanates, Ba and Pb chromates, carbon (eg carbon black, graphite etc.), glass (eg glass powder, glass beads etc.),
Examples are MgCO ₃ , fluorspar, and ZnS. Particularly preferred are silicic acid anhydride, hydrous silicic acid, aluminum oxide, aluminum silicate (calcined product,
(Including hydrates), 1 lithium phosphate, 3 lithium 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, diatomaceous earth Etc. are illustrated. Of these inert fine particles (II), externally added particles are particularly preferable.

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

Further, the inert particles (II) have an average particle diameter of 0.05 to 3 μm, but are used together as an average particle diameter smaller than that of the spherical silica particles (I).

The inert fine particles (II) preferably have an average particle size of 0.10 to 2.0 μm, more preferably 0.20 to 1.5 μm.

The content of the inert fine particles (II) is 0.005 to 3% by weight, preferably 0.01 to 2% by weight, more preferably 0.02 to 1.0% by weight, and particularly preferably 0.05 to 0.75% by weight, based on the polyether ether ketone. On the other hand, the content of the spherical silica particles (I) is 0.005 to 3% by weight based on the polyether ether ketone, but 0.01 to 2% by weight, further 0.02 to 1.0% by weight, and especially 0.02% by weight.
5 to 0.75% by weight is preferred.

If the content of the inert fine particles (II) or the spherical silica particles (I) is too small, the synergistic effect of using two kinds of particles, large and small, cannot be obtained, and the running property, wear resistance, fatigue resistance, crushing property, It is not preferable because characteristics such as end face uniformity are deteriorated. On the other hand, if the content of the inert particles (II) is too large, the frequency of occurrence of voids due to small particles in the polymer tends to increase, resulting in wear resistance, fatigue resistance, crush resistance, insulation voltage, and transparency. Sex and so on.

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

In the process of producing the biaxially oriented film of the present invention, spherical silica particles or inactive fine particles thereof and intimately mixed with polyether ether ketone can be intimately mixed by polymerizing these fine particles before or during the polymerization of polyether ether ketone. The polyether ether ketone may be sufficiently kneaded in an extruder for pelletizing after completion of the polymerization in a kettle, or in an extruder for melt extrusion into a sheet.

The biaxially oriented polyetheretherketone film of the present invention can be produced according to the conventionally accumulated method for producing a biaxially oriented film. For example, a polyether ether ketone containing spherical silica particles is melt-cast into an amorphous unstretched film, and then the unstretched film is biaxially stretched, heat set, and if necessary, a relaxation heat treatment. Is manufactured by At that time, the film surface characteristics vary depending on the particle size, amount, etc. of the spherical silica particles, and the stretching conditions. The density and heat shrinkage also change depending on the temperature, magnification, speed, etc. during drawing and heat treatment, so the conditions for simultaneously satisfying these characteristics are determined. For example, the stretching temperature is such that the first stage stretching temperature (for example, the longitudinal stretching temperature: T ₁ ) is (Tg−10) to (Tg +).
From the range of 45) ° C. (however, Tg: glass transition temperature of polyetheretherketone), the second stage stretching temperature (for example, transverse stretching temperature: T ₂ ) is (T ₁ +15) to (T ₁ +40) ° C.
It is good to select from the range. The stretching ratio may be selected from the range in which the uniaxial stretching ratio is 1.5 or more, particularly 2.5 or more, and the area ratio is 4 or more, particularly 6 or more. Furthermore, the heat setting temperature is 200-350 ℃, further 220-2
It is recommended to select from the range of 55 ℃. Heat setting time is 1
~ 20 seconds.

The thickness of biaxially oriented film is 1-250μm, more preferably 1-1
25 μm, particularly 1 to 75 μm is preferable.

The biaxially oriented polyether ether kent film of the present invention is characterized in that it has uniform uneven surface characteristics, excellent slipperiness, heat resistance and abrasion resistance, and that the amount of scrapes, white powder and the like is extremely small. This biaxially oriented polyetheretherketone film can be widely used for various applications by utilizing these characteristics. For example, when it is used as an electrical insulation material, motor insulation, and wire coating, excellent heat resistance and workability can be obtained. When used for capacitors, a high-grade capacitor having a high operating temperature can be obtained due to its low friction coefficient, excellent winding property, low crush load, and its excellent heat resistance. Also, F
When used for a PC (flexible printed circuit), it is possible to obtain an FPC having excellent solder resistance.
When used as a base film for magnetic recording such as video, audio, and computer, excellent electromagnetic conversion characteristics, slipperiness, running durability, etc. can be obtained.
In particular, it is suitable as a base film for vacuum deposition or sputtering in which a metal thin film is applied to the base film because of its heat resistance.

The biaxially oriented polyetheretherketone film is particularly preferable for electric shock, capacitor, FPC, and metal thin film magnetic recording medium, but is also widely used as a film for coating magnetic recording medium, vapor deposition, thermal transfer, etc. can do.

[Examples] Hereinafter, the present invention will be further described with reference to Examples. Various physical properties and characteristics in the present invention are measured as follows.

(1) Particle size The particle size can be measured in the following states.

1) To obtain the average particle size, particle size ratio, etc. from silica powder 2) To obtain the average particle size, particle size ratio, etc. of silica particles in the film 1) From silica powder: Electron microscope sample table Silica powder is scattered on the top so that individual particles do not overlap as much as possible, and a gold thin film deposition layer is formed on this surface with a thickness of 200 Å to 300 Å by a gold sputtering device, and 10,000 to 30,000 times with a scanning electron microscope. Observed with a Luzex 500 manufactured by Nippon Regulator Co., Ltd., and at least 100 particles have a long diameter (Dli) and a short diameter (Dsi).
And the equivalent circle diameter (Di). Then, the number average value represented by the following equation represents the major axis (Dl), the minor axis (Ds), and the average particle diameter () of the silica particles.

2) In the case of silica particles in the film: A small piece of the sample film is fixed on a sample stand for a scanning electron microscope, and a sputtering device (JFC-110 manufactured by JEOL Ltd.) is used.
The film surface is subjected to an ion etching treatment under the following conditions using a 0 type ion sputtering device). The condition is that the sample is placed in a bell jar, the degree of vacuum is raised to a vacuum state of about 10 ⁻³ Torr, and ion etching is performed for about 10 minutes at a voltage of 0.25 KV and a current of 1.25 mA. Further, the film surface is gold-sputtered by the same apparatus and observed with a scanning electron microscope at a magnification of, for example, 10000 to 30000, and at least 100 particles have a long diameter (Dli) and a short diameter using a Luthesque 500 manufactured by Nippon Regulator Co., Ltd. Diameter (Dsi) and area equivalent circle diameter (D
i) is calculated. Thereafter, the same procedure as 1) above is performed.

(2) Film surface roughness (Ra) It is a value defined by JIS-B0601 as the center line average roughness (Ra), and in the present invention, a stylus surface roughness meter (SURFCORDER SE of Kosaka Laboratory Ltd.) -30C). The measurement conditions are as follows.

(a) Stylus tip radius: 2 μm (b) Measuring pressure: 30 mg (c) Cut-off: 0.25 mm (d) Measuring length: 0.5 mm (e) How to put together the data Value 1
Exclude one, round off the fourth decimal place of the average value of the remaining four data, and display up to the third decimal place.

(3) Void ratio According to the method of (1) -2) above, the periphery of the lubricant in the film (surface) is exposed, and the major axis of at least 50 solid fine particles and the major axis of the void are measured. It is expressed by the number average value of the void ratio obtained in step 1.

(4) Frictional coefficient of film (μk) The angle θ = 152 on the fixed rod (surface roughness 0.3 μm) of the film cut into 1/2 inch width in the environment of temperature 20 ° C and humidity 60%
Make contact with / 180π radians (152 °) and move (rub) at a speed of 200 cm per minute. The exit tension (T ₁ : g) when the tension controller was adjusted so that the entrance tension T ₁ would be 35g was detected by the exit tension detector after the film had run 90m, and the running wear coefficient μk was calculated by the following formula. calculate.

μk = (2.303 / θ) log (T 2 / T 1) = 0.868 log (T 2/35) (5) Haze (Haze) according to JIS-K 674, Nihon Seimitsu optical Co., integrating sphere HTR meter To obtain the film haze.

(6) Dielectric breakdown voltage and abnormal dielectric breakdown rate The dielectric breakdown voltage is measured by the method specified in JIS-C-2318. Adopt an average value of n = 100, and 1/3 of this average value
The ratio (%) of the following values is defined as the dielectric breakdown abnormality rate.

(7) Evaluation of element end face shape after unevenness and flattened element end face shape Aluminum vapor deposition of 10μ film, slit into 20mm width, winding tension of 40g on winding core of 3mm outer diameter, winding speed 3
An element wound with a length of 4 m at 0 cm / sec was made. Regarding the unevenness of the element end faces, the ones whose edge faces were perfectly aligned were marked with ○, and some of them were slightly uneven, but the extent was also small. , Those that can be used practically are marked with △, and those that cannot be used are marked with ×.

When the element was flattened by pressing, the end face shape after flattening was evaluated as follows: ○ The film layers were flattened in a straight line with no gaps, and there were no gaps in practical use. If there is no crushing and the film is not uniform and there are gaps between the film layers, it cannot be used.

(8) Comprehensive evaluation of capacitors Comprehensive evaluation of electrical properties such as crushability, winding workability, handling workability, vapor deposition processability, dielectric breakdown voltage, and dielectric breakdown anomaly rate. A sample having a slightly inferior surface but having no problem in practical use is evaluated as ○, a sample having practical problems is evaluated as Δ, and a product that cannot be used is evaluated as ×.

(9) Lubricant Aggregation The film is magnified 20 times under polarized light, and the polarizing plates are orthogonalized, and the number of agglomerated lubricants having a size of 25 μm or more among those shining in a dark field is evaluated. The measurement area shall be 10 cm ² , 0 to 10 per cm shall be ○, 10 to 30 shall be △, and 30 or more shall be ×.

Examples 1 to 7 Spherical silica particles and inert particles were mixed with polyether ether ketone (polyether ether ketone 380G manufactured by ICI) in the proportions shown in Table 1, and after blending, extruded at 380 ° C. with an extruder to give 80 Cast on a casting drum maintained at a temperature of ℃, create an unstretched film of 90μm, stretch it 2.5 times in the machine direction at 160 ℃, and feed it to a tenter, then stretch it 3.5 times in the transverse direction at 160 ℃. And 250 ℃
Fixed for 30 seconds.

The characteristics of these films are shown in Table 1.

Comparative Examples 1 to 3 The same polymer as in Example 1 was used, and only the lubricant was changed to those shown in Table-1, and the same procedure as in Example 1 was performed. 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 is a film having a flat surface, a small coefficient of repeated friction, and excellent lubricity. Further, it can be seen that the film of the present invention has less aggregation of the lubricant, and is very excellent as a base for capacitors.

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Claims (3)

[Claims] 1. A polyether ether ketone having an average particle size of 0.05 to 4 μm and a particle size ratio (major axis / minor axis) of 1.
A biaxially oriented polyetheretherketone film containing 0.01 to 3% by weight of spherical silica particles of 0 to 1.2. 2. A biaxially oriented polyether ether kent film according to claim 1, wherein the spherical silica particles have a relative standard deviation represented by the following formula of 0.5 or less. Here, Di: area circle equivalent diameter of each particle (μm): average value of area circle equivalent diameter (μm) n: represents the number of particles. 3. Spherical silica particles (I) having an average particle diameter of 0.2 to 4 μm and a particle diameter ratio (major axis / minor axis) of 1.0 to 1.2 in 0.005 to 3 of polyether ether ketone.
%, And (II) 0.005 to 3% by weight of inactive fine particles having an average particle size of 0.05 to 3 μm, the average particle size of which is smaller than the average particle size of spherical silica particles. Biaxially oriented polyetheretherketone film.