JPH03140336A - Biaxially oriented thermoplastic resin film - Google Patents

Abstract

PURPOSE:To obtain the subject film having particular surface and excellent abrasion resistance and electrical insulation and suitable for magnetic recording medium, packaging film, capacitor film, etc., by using a thermoplastic resin containing inert particles such as spherical titanium oxide particles having a specific particle diameter as a main component. CONSTITUTION:The objective film having a thickness of 0.01-3mum is composed of (A) a thermoplastic resin (e.g. a crystalline polyester having a total reflection Raman crystallization index of <=20cm<-1>) and (B) 2-20wt.% of inert particles dispersed in the resin, having an average particle diameter corresponding to 0.2-5 times the thickness of the film and a relative standard deviation of <=0.6 and selected from spherical titanium oxide particle, spherical tungsten oxide particle, spherical molybdenum oxide particle and spherical silicone particle. Since the film has specific surface structure, the friction coefficient can be compatibilized with the output characteristics of a magnetic recording medium in high dimensional viewpoint and the film is useful for improving the picture quality of a video tape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a biaxially oriented thermoplastic resin film.

[Prior Art] As a biaxially oriented thermoplastic resin film, a film with improved runnability on at least one side is known (for example, JP-A-59-171623, etc.).

[Problems to be Solved by the Invention] However, with the above-mentioned conventional biaxially oriented thermoplastic resin film, for example, the magnetic layer application in magnetic media applications, the calendering process, or the dubbing of the resulting videotape etc. into soft tapes etc. As the process speed increases in the manufacturing process, etc., there has been a drawback that the film surface is scratched by the contacting rolls and guides. In addition, in the conventional
Due to the deterioration in image quality during dubbing, the image quality when converted to videotape, that is, the S/N (signal/noise ratio), was also insufficient.

The present invention has solved these problems, and has two types of film that are particularly resistant to scratches in high-speed processes (hereinafter referred to as "excellent scratch resistance") and have less deterioration in image quality during dubbing (hereinafter referred to as "excellent dubbing resistance"). The object is to provide an axially oriented thermoplastic resin film.

[Means for Solving the Problems] The present invention is based on a thermoplastic resin A containing inert particles selected from spherical titanium oxide particles, spherical tungsten oxide particles, spherical molybdenum oxide particles, and spherical silicone particles. A film having a thickness of 0.01, characterized in that the average particle diameter of the particles is 0.2 to 5 times the thickness of the film, and the content of the particles is 2 to 20% by weight.
It concerns a biaxially oriented thermoplastic resin film of ~3 μm.

The thermoplastic resin A constituting the present invention is not particularly limited to polyester, polyolefin, polyamide, polyphenylene sulfide, etc., but polyester, especially ethylene terephthalate, ethylene α, β-bis(2
- Scratch resistance and dubbing resistance are even better when the main constituent is at least one structural unit selected from chlorophenoxy)ethane-4,4'-dicarboxylate and ethylene 2,6-naphthalate units. Therefore, it is desirable. Further, it is extremely desirable that the thermoplastic resin constituting the present invention be crystalline or optically anisotropic when melted, since this will further improve scratch resistance and dubbing resistance. Crystallinity here means that it is not so-called amorphous, and quantitatively, the cold crystallization temperature Tcc in the crystallization parameter is detected, and the crystallization parameter ΔTcg is 150° C. or less. Furthermore, it is extremely desirable that the heat of fusion (change in enthalpy of fusion) measured by a differential scanning calorimeter exhibits crystallinity of 7.5 cal/g or more, since scratch resistance and dubbing resistance will be even better. In addition, polyester containing ethylene terephthalate as a main component is particularly desirable because it has even better dubbing resistance and scratch resistance. Note that two or more types of thermoplastic resins may be mixed or a copolymer may be used within a range that does not impede the present invention.

The inert particles in the thermoplastic resin A of the present invention have even better scratch resistance, especially when they are spherical particles.

In the present invention, spherical particles refer to particles having a particle diameter ratio (longer diameter/breadth diameter of particles) of 1.0 to 1.3, preferably 1.0 to 1.2.

Furthermore, when the relative standard deviation of the particle size of the inert particles in the thermoplastic resin A of the present invention is 0.6 or less, preferably 0.5 or less, the scratch resistance and dabbing resistance will be even better. desirable.

The inert particles in the thermoplastic resin A of the present invention are particles selected from spherical titanium oxide particles, spherical tungsten oxide particles, spherical molybdenum oxide particles, and spherical silicone particles, thereby improving scratch resistance and dabbing resistance. Even better.

Regarding the size of the inert particles, it is necessary that the average particle diameter in the film is in the range of 0.2 to 5 times, preferably 0.5 to 5 times, more preferably 161 to 3 times the film thickness. It is. If the average particle diameter/film thickness ratio is smaller than the above range, the scratch resistance will be poor, and if it is too large, the scratch resistance and dubbing resistance will be poor, which is not preferable.

The present invention is extremely desirable because when the specific particles selected from the above are used in a specific film thickness and 7 particle diameter ratio, the scratch resistance and dubbing resistance are particularly good.

Also, the average particle size (diameter) of inert particles in thermoplastic resin A
is in the range of 0.01 to 1 .mu.m, particularly 0.602 to 0.5 .mu.m, as this provides even better scratch resistance and dubbing resistance.

The content of inert particles in the thermoplastic resin A of the present invention is from 2 to
It is necessary that the amount is 20% by weight, preferably 2 to 10% by weight, and more preferably 3 to 8% by weight. Even if the content of inert particles is less than the above-mentioned range, it is not preferable that the content is greater than the above range because the scratch resistance becomes poor.

The main component of the film of the present invention is a composition consisting of the thermoplastic resin A and inert particles, but other types of polymers may be blended within a range that does not impede the purpose of the present invention, and antioxidants may be added. , heat stabilizers, lubricants, ultraviolet absorbers, and other organic additives may be added to the extent that they are normally added.

The film of the present invention is a film in which the above composition is biaxially oriented. - Axial or non-oriented films have poor scratch resistance, so the preferred degree of orientation is 0°.The degree of orientation is not particularly limited, but the Young's modulus, which is a measure of the degree of molecular orientation of polymers, is 350° in both the longitudinal and width directions. kg g
/mm2 or more is extremely desirable because the scratch resistance becomes even better. The upper limit of Young's modulus, which is a measure of the degree of molecular orientation, is not particularly limited, but is usually 1
The manufacturing limit is about 500 kg/mai2.

In addition, even if the Young's modulus of the film of the present invention is within the above range, the orientation of the polymer molecules in a portion of the thickness direction of the film, for example, near the surface layer, is not oriented or is not oriented in the -axis direction, i.e. It is particularly preferable that the molecular orientation in the entire thickness direction is biaxial because the scratch resistance and dubbing resistance will be even better.

In particular, scratch resistance and dubbing resistance are even better when the molecular orientation measured by Atsube refractometer, laser refractometer, total internal reflection laser Raman method, etc. is biaxially oriented on both the front and back surfaces. This is particularly desirable.

Further, the thermoplastic resin A is a crystalline polyester, and the total reflection Raman crystallization index of the surface thereof is 20 Cm-' or less,
Preferably, the thickness is 18 cm-' or less, and more preferably 17 crrr' or less, which is extremely desirable because scratch resistance and dubbing resistance are even better.

The thickness of the film of thermoplastic resin A of the present invention is 0°01~
It is necessary that the thickness is 3 μm, preferably 0.02 to 1 μm, and more preferably 0.03 to 0.5 μm. If the film thickness is smaller than the above range, the dubbing resistance will be poor, and if it is larger than the above range, the scratch resistance will be poor, which is not preferable.

When the average protrusion height on the surface of the thermoplastic resin A film of the present invention is in the range of 5 to 500 nm, preferably 10 to 300 nm, more preferably 15 to 200 nm, the scratch resistance and dubbing resistance are even better. This is particularly desirable.

The average distance between the protrusions of the film on the thermoplastic resin of the present invention is 6
It is particularly desirable that the thickness be less than .mu.m, preferably less than 4 .mu.m, since scratch resistance and dubbing resistance will be even better.

As mentioned above, it is extremely desirable for the thermoplastic resin constituting the film of the present invention to be crystalline or melt optically anisotropic, but in the case of a melt isotropic film, the crystallization parameter ΔTcg is 25 to 65°C. This is particularly desirable since the scratch resistance will be even better in some cases.

In addition, when the thermoplastic resin A is polyester, it is particularly preferable that the refractive index of the thermoplastic resin A surface in the thickness direction is 1.5 or less, since the scratch resistance and dubbing resistance will be even better. Furthermore, the intrinsic viscosity of the film is 0.60 or more,
In particular, when it is 0.70 or more, the scratch resistance becomes even better, so it is particularly desirable.

The film of the present invention can of course be used alone (single layer film), but if it is used in the form of a biaxially oriented film after laminating a film of thermoplastic resin A on at least one side of a film of thermoplastic resin B, This is extremely desirable because not only the mechanical properties are improved, but also the scratch resistance and dubbing resistance are further improved. Here, the thermoplastic resins A and B may be the same type or different types.

As the thermoplastic resin B, a crystalline polymer is preferable, and it is particularly preferable that the crystallinity parameter ΔTcg is in the range of 20 to 100° C. because the dubbing resistance becomes even better. Specific examples include polyester, polyamide, polyphenylene sulfide, and polyolefin, but polyester is particularly preferred because it has even better dubbing resistance. In addition, as polyester,
Ethylene terephthalate, ethylene α, β-bis(2-
It is preferable that at least one structural unit selected from chlorophenoxy)ethane-4,4'-dicarboxylate and ethylene 2,6-naphthalate units be used as the main constituent, since the dubbing resistance will be particularly good. however,
Other components may be copolymerized within a range that does not impede the present invention, within a range that does not impair desirable crystallinity, and preferably within 5 mol%.

The thermoplastic resin B of the present invention may also be blended with other types of polymers within the range that does not impede the purpose of the present invention, and organic additives such as antioxidants, heat stabilizers, lubricants, and ultraviolet absorbers may be added. The agent may be added to the extent that it is normally added.

There is no particular need to contain inert particles in the film of thermoplastic resin B, but if the average particle size is 0°01 to 2 μm1
In particular, inert particles of 0.02-0.5 μm are 0.001-
A content of 0.15% by weight, particularly 0.005 to 0.05% by weight, is extremely desirable because not only the scratch resistance is improved, but also the winding appearance of the film is improved.

The types and sizes of particles contained in thermoplastic resins A and B may be the same or different.

The difference (A-B) in crystallization parameter ΔTcg between thermoplastic resin A and thermoplastic resin B is not particularly limited, but is -3
A temperature of 0 to +20° C. is particularly desirable because scratch resistance and dubbing resistance become even better.

Next, a method for producing the film of the present invention will be explained.

First, as a method for incorporating inert particles into thermoplastic resin A, when the thermoplastic resin is polyester, it is dispersed in the form of a slurry of ethylene glycol, which is a diol component, and this ethylene glycol is mixed with a predetermined dicarboxylic acid component. It is effective to obtain a film having a relationship between thickness and average particle size and content within the range of the present invention. In addition, by adjusting the melt viscosity, copolymerization components, etc. of the polyester containing inert particles, its crystallization parameter ΔTc
A method of keeping g in the range of 40 to 65°C is effective for obtaining a film having the relationship between thickness and average particle size and content within the range of the present invention.

Additionally, a slurry of ethylene glycol of inert particles was added to
A method of heat treatment at a temperature of 40 to 200°C, especially 180 to 200°C for 30 minutes to 5 hours, especially 1 to 3 hours, is effective for obtaining a film with the relationship between thickness and average particle size and content within the range of the present invention. be.

In addition, as a method for incorporating inert particles into a thermoplastic resin, the particles are heat-treated in ethylene glycol, and then mixed with the thermoplastic resin in the form of a slurry in which the solvent is replaced with water.
The method of kneading and kneading into thermoplastic resin using a vent-type twin-screw press ratio machine also has the relationship between the thickness and average particle size within the range of the present invention,
It is very effective to obtain a film with high content.

A method for adjusting the particle content is to prepare a high-concentration master using the above method, and then dilute it with a thermoplastic resin that does not substantially contain inert particles during film formation to adjust the particle content. The method is valid.

After drying the pellet containing a predetermined amount of inert particles as necessary, it is supplied to a known melt extruder and extruded into a sheet through a slit-shaped die at a temperature above the melting point and below the decomposition point of the thermoplastic resin. It is cooled and solidified on a casting roll to form an unstretched film. In this case, when extruding into an unstretched film, the ratio of die slit gap/unstretched film thickness should be in the range of 5 to 30, preferably 8 to 20. ,
It is effective to obtain films with a range of contents.

Next, this unstretched film is biaxially stretched and biaxially oriented. As the stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. However, by using a sequential biaxial stretching method that first stretches in the longitudinal direction and then in the width direction, the longitudinal stretching is divided into three or more stages, and the total longitudinal stretching ratio is 3.
．． The method conducted at a magnification of 0 to 6.5 times is effective for obtaining a film having a relationship between thickness and average particle size and content within the range of the present invention.

However, when the thermoplastic resin is a molten optically anisotropic resin, a longitudinal stretching ratio of 1.0 to 1.1 times is appropriate.

Although the longitudinal stretching temperature varies depending on the type of thermoplastic resin and cannot be generalized, it is usually 50 to 130 ℃ in the first stage.
°C, and higher than that in the second and subsequent stages.It is effective to obtain a film with the relationship between thickness and average grain size within the range of the present invention, content, and orientation state within the desired range.Longitudinal stretching speed is preferably in the range of 5.000 to 50,000%/min.

A common method for stretching in the width direction is to use a stenter. The appropriate stretching ratio is 3.0 to 5.0 times. The stretching speed in the width direction is 1.000 to 20.00
0%/min and the temperature is preferably in the range of 80 to 160°C.

Next, this stretched film is heat treated. In this case, the heat treatment temperature is preferably 170 to 200°C, particularly 170 to 190°C, and the time is preferably in the range of 0.5 to 60 seconds.

Next, as a method for laminating a film of thermoplastic resin A on at least one side of a film of thermoplastic resin B, the following method is effective.

Predetermined thermoplastic resin-containing composition and thermoplastic resin B (A, B
may be the same or different types) is fed to a known melt lamination extruder and extruded into a sheet from a slit-shaped die,
It is cooled and solidified on a casting roll to form an unstretched film. That is, using 2 or 3 extruders, 2 or 3 layer manifolds or merging blocks,
Thermoplastic resins A and B are laminated, two or three layers of sheets are extruded from a die, and the sheets are cooled with a casting roll to form an unstretched film. In this case, a method of installing a static mixer gear pump in the polymer flow path of thermoplastic resin A is effective for obtaining a film having the relationship between thickness and average particle size and content within the range of the present invention. In addition, the melting temperature of the extruder on the thermoplastic resin A side was set to 10 to
Increasing the temperature by 40°C is effective in obtaining a film having the relationship between thickness and average grain size, content within the range of the present invention, and orientation state within the desired range.

Next, the points of the method for biaxially stretching this unstretched film to achieve biaxial orientation are basically the same as those for the single-layer film described above. However, in the case of a laminated film, the stretching temperature must be set based on thermoplastic resin A. Furthermore, in the heat treatment process of the two-layer laminated film, the temperature of the hot air blown around the thermoplastic resin A should be lowered by 3 to 20 degrees Celsius than that of the thermoplastic resin B layer. This is effective in obtaining a film with a desired range of orientation.

[Method for Measuring Physical Properties and Evaluating Effects] The methods for measuring the characteristic values and evaluating the effects of the present invention are as follows.

(1) Average particle size of particles The thermoplastic resin is removed from the film by plasma low-temperature ashing treatment to expose the particles. The processing conditions are selected so that the thermoplastic resin is incinerated but the particles are not damaged.

At least 5,000 particles were observed using a scanning electron microscope, the particle images were processed using an image processing device, and the number average diameter determined by the following formula was defined as the average particle diameter.

D=ΣDi/N Here, Df is the circle-equivalent diameter of the particle, and N is the number of particles.

(2) Particle size ratio In the measurement of (1) above, the average value of the long diameter of each particle /
It is the ratio of the average value of the short axis.

That is, it can be obtained using the following formula.

Major axis = ΣDli/N Minor axis = ΣD2i/N [)li, D2i are the major axis (maximum diameter) and minor axis (shortest axis) of each individual particle, and N is the total number.

(3) Relative standard deviation of particle diameter Individual particle diameter Di1 average mean diameter 9 (=(Σ(D i −D) '/N) '') measured by the method in (1) above is calculated as the average diameter. It is expressed as the value divided by (σ/D).

(4) Particle content A solvent that dissolves the thermoplastic resin but does not dissolve the particles is selected, the particles are centrifuged from the thermoplastic resin, and the ratio (weight %) to the total weight of the particles is defined as the particle content. In some cases, infrared spectroscopy may also be effective.

(5) Crystallization parameter 610g Heat of fusion was measured using a differential scanning calorimeter. The measurement conditions are as follows. That is, sample Long was set in a differential scanning calorimeter, and 30
After melting for 5 minutes at a temperature of 0° C., it is quenched in liquid nitrogen. This rapidly cooled sample was heated at a rate of 10°C/min, and the glass transition point T
g is detected. The temperature was further increased, and the exothermic peak temperature of crystallization from the glass state was defined as the cold crystallization temperature Tcc. The temperature was further increased, and the heat of fusion was determined from the melting peak.

Here, the difference between Tcc and Tg (Tcc - Tg) was defined as the crystallization parameter ΔTcg.

(6) Molecular orientation (refractive index) on the surface, total reflection Raman crystallization index on the surface Measured using an Atsube refractometer using sodium D line (589 nm) as a light source. Methylene iodide was used as the mounting solution, and the measurement was performed at 25° C. and 65% RH. The biaxial orientation of the polymer has a refractive index of N in the longitudinal direction, width direction, and thickness direction.
, , N2, N, the absolute value of (Nl - N2 ) is 0507 or less, and N3 / [(Nu + N2
)/2] is 0.95 or less. Alternatively, the refractive index may be measured using a laser refractometer. Furthermore, if measurement is difficult with this method, total internal reflection laser Raman method can also be used.

Laser total internal reflection Raman measurement is performed by Jobin-Yvon
The total reflection Raman spectrum is measured using a Ran+anor U-1000 Raman system manufactured by the company.For example, in the case of polyethylene terephthalate, the polarization of the band intensity ratio of 1615 cm (skeletal vibration of benzene ring) and 1730 cm-' (stretching vibration of carbonyl group) is determined. Measurement ratio (YY/X
X ratio etc. Here, YY: polarization direction of the laser is set to Y and the detection of the man light parallel to Y, Xx: the direction of polarization of the laser is set to X and the detection of the man light parallel to Available. The biaxial orientation of a polymer can be determined by converting the parameters obtained from Raman measurement into refractive indices in the longitudinal direction and width direction, and based on their absolute values, differences, etc. It is also a stretching vibration of carbonyl group], 730
The half width in cm-' was taken as the total reflection Raman crystallization index of the surface. The measurement conditions in this case are as follows.

■Light source Argon ion laser (5145A) ■Setting the sample The surface of the film is pressed against a total reflection prism, and the incident angle of the laser to the prism (angle with the film thickness direction) is 60°.
'.

■Detector PM: RCA31034/Photon Coun
liB S7slem (flamaS75le C12
31)) (supply 1600V) ■Measurement conditions 5LIT 1000μm LASERI [
lOmW GATE TIME +, θ5ecSCAN
5PEED 12cF'/minSAMPLI
NG INTER1'AL 02cmREPEAT T
IIVE6 (7) Average height of surface protrusions 2 The measured value of the height of the protrusions when scanning with the height of the flat surface of the film surface as 0 using a two-detector type scanning electron microscope and a cross-sectional measuring device is measured by the image processing device. to reconstruct the film surface protrusion image on an image processing device. Also, these 2
The highest value among the valued individual protrusion portions is determined as the height of the protrusion, and this value is determined for each protrusion. This measurement was repeated 500 times at different locations, and the average value of the heights of all the measured protrusions was taken as the average height. The magnification of the scanning electron microscope is selected to be between 1,000 and 10,000 times.

(8) Young's modulus J15-Z-1702
Measured at 65% RH.

(9) Intrinsic viscosity [η (unit: 617 g) A value calculated from the following formula from the solution viscosity measured at 25°C in orthochlorophenol is used.

That is, η,, /C= [η] +K [ηko 2 ・Nikode, η3. = (solution viscosity/solvent viscosity) -1, C is solvent 1
Dissolved polymer weight per 00ml (g/100ml
．． Usually 1.2), K is Huggins constant (assumed to be 0,343). In addition, solution viscosity and solvent viscosity were measured using an Ostwald viscometer.

(10) A scratch-resistant film slit into a 1/2 inch wide tape was run on a guide pin (surface roughness: Ra, 10100n) using a tape runnability tester (running speed f , 000 m/min, number of running passes: 10, winding angle: 0°, running tension: 65 g).

At this time, the scratches in the film were observed under a microscope, and the width was 2.
If there were less than two scratches per tape width of 5 μm or more, it was determined to be excellent, if there were 2 or more and less than 10 scratches, it was determined to be good, and if there were 10 or more scratches, it was determined to be poor. Excellent is desirable, but good is still usable for practical purposes.

(11) A magnetic paint having the following composition is applied to a dubbing-resistant film using a gravure roll, magnetically oriented, and dried. In addition, a small test calender device (steel roll/nylon roll,
After calendering at a temperature of near 0°C and a linear pressure of 200 kg/cm, the product was cured at 70°C for 48 hours. The original tape was slit into 1/2 inch pieces to make pancakes. A length of 250 m from this pancake was assembled into a VTR cassette to make a VTR cassette tape.

(Composition of magnetic paint) Co-containing iron oxide = 100 parts by weight Vinyl chloride/vinyl acetate copolymer: 10 parts by weight Polyurethane elastomer: 10 parts by weight Polyisocyanate): 5ffiffi parts Lecithin 2 1 part by weight Methyl ethyl ketone Nia 5 parts by weight / Methyl isobutyl ketone Nia 5 parts by weight / Toluene
Near 5 parts by weight/carbon black:
2 parts by weight Lauric acid: 1.5 parts by weight A 100% chroma signal was recorded on this tape using a TV test waveform generator using a home VTR, and the chroma S/N was measured from the playback signal using a color video noise measuring device. It was measured and marked as A. Also, after dubbing the pancake of the master tape on which the same signal as above was recorded onto the pancake of the same sample tape (unrecorded) on which A was measured using a magnetic field transfer video software high-speed print system (Sprinter). The chroma S/N of the tape was measured in the same manner as above, and it was designated as B. Decrease in chroma S/N due to this dubbing (
If A-B) is less than 3dB, dubbing resistance: Excellent, 3d
A value of B or more and less than 5 dB was determined to be good, and a value of 5 dB or more was determined to be poor. Excellent is desirable, but good is still usable for practical purposes.

[Example] The present invention will be explained based on examples.

Examples 1 to 4, Comparative Examples 1 to 4 Ethylene glycol slurry containing spherical titanium oxide particles, spherical molybdenum oxide particles and colloidal silica having different average particle sizes was prepared, and this ethylene glycol slurry was heated at 190°C for 1.5 hours. After heat treatment, the mixture was transesterified with dimethyl terephthalate and then polycondensed to produce pellets of polyethylene terephthalate containing 1-10% by weight of the particles. At this time, the polycondensation time was adjusted so that the intrinsic viscosity was 0.65 (thermoplastic resin A). In addition, polyethylene terephthalate having an intrinsic viscosity of 0.62 and containing substantially no inert particles was produced as thermoplastic resin B by a conventional method. Each of these polymers was heated to 180°C.
The mixture was dried under reduced pressure (3 Torr) for 6 hours. Thermoplastic resin A
is supplied to extruder 1 and melted at 290°C, furthermore, thermoplastic resin B is supplied to extruder 2 and melted at 285°C, these polymers are merged and laminated in a merging block (feed block), and electrostatic charge is applied. Using a casting method, it was wound around a casting drum with a surface temperature of 25° C., and cooled and solidified to produce an unstretched film with a two-layer structure. At this time, an unstretched film was prepared with the ratio of die slit gap/unstretched film thickness to 10. In addition, the total thickness and the thickness of the six thermoplastic resin layers were adjusted by adjusting the discharge rate of each extruder. This unstretched film was stretched 3.5 times in the longitudinal direction at a temperature of 85°C. This stretching was carried out in four stages with a difference in peripheral speed between two sets of rolls. This axially stretched film was stretched 4°0 times in the width direction at 100°C at a stretching rate of 2,000%/min using a stenter, and then heat-treated at 210°C for 5 seconds at a constant length to reduce the total thickness. Thickness: 15 μm, thermoplastic resin A layer thickness: 0°02~7
．． A biaxially oriented laminated film of 5 μm was obtained.

The parameters of the present invention for these films are as shown in Table 1, and when the parameters of the present invention were within the range, the scratch resistance and dubbing resistance were excellent or good as shown in Table 1. However, in other cases, a film having both scratch resistance and dubbing resistance could not be obtained.

[Effects of the Invention] The present invention uses specific particles to create a film with a special surface morphology that could not be obtained conventionally, so it has an extremely high coefficient of friction and output characteristics when used for magnetic recording media. A film that is compatible with both dimensions has been obtained, and will be useful for improving the image quality of future videotapes. Furthermore, due to the unique surface, the film has excellent abrasion resistance and can withstand severe use, making it suitable for increasing film processing speeds in various applications. Applications of the film of the present invention are not particularly limited, but in addition to the above-mentioned magnetic recording media, it can also be used for packaging that takes advantage of the handling properties related to the coefficient of friction and the good transparency resulting from the special surface, and furthermore, for packaging that takes advantage of the good transparency resulting from the special surface. It can be used in a wide variety of applications, such as capacitors, which take advantage of its good electrical insulation properties. Note that for films of the present invention with a two-layer structure, the surface having a surface morphology within the scope of the present invention is a non-functional surface (the surface on which no magnetic layer is coated for magnetic recording media, and the surface for printing or other coating materials for other uses). It is desirable to use it as a surface that has not been subjected to any treatment such as coating.

Claims (5)

[Claims] (1) A film mainly composed of thermoplastic resin A containing inert particles selected from spherical titanium oxide particles, spherical tungsten oxide particles, spherical molybdenum oxide particles, and spherical silicone particles, The average particle size is 0.2 to 5 times the film thickness, and the particle content is 2
Thickness 0.01-3, characterized in that it is ~20% by weight
μm biaxially oriented thermoplastic resin film. (2) Thermoplastic resin B that does not substantially contain inert particles
Claim (1) on at least one side of the film mainly composed of
) A biaxially oriented thermoplastic resin film obtained by laminating the thermoplastic resin films described in ). (3) Inert particles with an average particle size of 0.01 to 2 μm.
A biaxially oriented thermoplastic resin film obtained by laminating the thermoplastic resin film according to claim 1 on at least one side of a film whose main component is thermoplastic resin B containing 0.001 to 0.15% by weight. (4) The biaxially oriented thermoplastic resin film according to any one of claims (1) to (3), wherein the relative standard deviation of the particle size of the inert particles contained in the thermoplastic resin A is 0.6 or less. (5) Thermoplastic resin A is crystalline polyester, and the total reflection Raman crystallization index of the thermoplastic resin surface is 2.
Claim (1) characterized in that it is 0 cm^-^1 or less
The biaxially oriented thermoplastic resin film according to any one of ) to (4).