JPH0270727A - Biaxially oriented thermoplastic resin film - Google Patents

Abstract

PURPOSE:To improve scratch resistance by specifying the distribution of the concn. of inert particles in a film consisting mainly of a thermoplastic resin and the inert particles. CONSTITUTION:A pelletized thermoplastic resin contg. a specified amt. of inert particles with a degree of vacuum of not more than 1.6 is extruded into a sheet and set by cooling to give an unstretched film, which is stretched in the longitudinal direction at a temp. within the range of from 10 deg.C lower to 10 deg.C higher than the glass transition paint of the resin at a stretching rate of 1,000-10,000%/min, and then stretched in the transverse direction at a relative humidity of 50% and a temp. within the range of from 10 deg.C lower to 30 deg.C higher than the glass transition paint at the stretching rate of 1,000-20,000%/min to give a biaxially oriented thermoplastic resin film wherein a depth (a distance from the surface), A nm, at a point where the particle concn. is one tenth of that at the surface and a depth, B nm, at a point (B>A) where the particle concn. is the same as that at the surface satisfy relations I and II in a distribution curve of the particle concn. measured from at least one surface of the film to a point of 3,000nm deep.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a biaxially oriented thermoplastic resin film, and a magnetic recording medium and a thermal transfer material using the same.

[Prior Art] As a biaxially oriented thermoplastic resin film, a film made of polyester containing inert inorganic particles is known (for example, JP-A-59-171623@). As magnetic recording media and heat-sensitive transfer materials, there are known ones in which a magnetic layer or a heat-sensitive transfer layer is provided on at least one side of a polyester film (for example, Japanese Patent Laid-Open No. 59-20322
8M Publication, Japanese Unexamined Patent Publication No. 62-95289).

[Problems to be Solved by the Invention] However, the above conventional biaxially oriented thermoplastic resin film has the following problems:
As process speeds increase in film processing processes, such as printing processes for packaging, magnetic layer coating, and calendaring processes, the disadvantage is that the surface of the film is scratched by contact rolls, etc. Recently, this has become a problem.In addition, as the operating conditions have become more severe, the disadvantage of scratches on the surface and underside of the conventional magnetic recording media and thermal transfer materials mentioned above has recently become a problem. .

It is an object of the present invention to solve this problem and provide a film, a magnetic recording medium, and a heat-sensitive transfer material that do not get scratched even when running at high speed (hereinafter referred to as having good scratch resistance).

[Means for Solving the Problems] The present invention provides: (1) A film whose main component is a composition consisting of a thermoplastic resin and inert particles, which is measured to a depth of 3000 nm from the surface of at least one side of the film. In the concentration distribution curve of inert particles, the depth (distance from the surface) Anm where the particle concentration is 10 times the surface layer particle concentration value and the depth Bnm where the particle concentration is the same as the surface layer particle concentration value (B>A
The present invention relates to a biaxially oriented thermoplastic resin film, and a magnetic recording medium and a thermal transfer material using the biaxially oriented thermoplastic resin film, in which the relationship of > satisfies the following formulas (i) and (11).

10≦B-A≦1500... (i) 5≦A≦50
(ii) The thermoplastic resin in the present invention is not particularly limited, and polyester, polyamide, polyolefin, polyphenylene sulfide, etc. can be used, but polyester, especially ethylene terephthalate, ethylene α, β-bis(2 -chlorophenoxy)ethane-4,4-dicarboxylate, ethylene 2
．． It is preferable to use polynisder whose main constituent is at least one type of structural unit selected from 6-naphthalate units because the effect when the particle concentration structure of the present invention is adopted is even more remarkable.

It is particularly desirable that the inert particles used in the present invention have a sphericity of 1.6 or less, preferably 1.5 or less, and most preferably 1.3 or less, since the scratch resistance will be even better. The type of inert particles is not particularly limited, but substantially spherical silica caused by colloidal silica, tungsten oxide, and organic polymer particles with a 10% weight loss of 350°C or higher have better scratch resistance. This is particularly desirable since it provides even better results. The average particle size of the particles is not particularly limited and the preferable range varies depending on the type, but when the average particle size is c (nm), (B-A in the above formula (i)
The scratch resistance becomes even better when the relationship between This is particularly desirable because the properties are even better.

1.0≦c/ (B-A>≦3.5 --(a)1.3
≦c/ (B-A)≦3.0 (b) The film of the present invention contains the above composition as a main component, but other types of polymers may be blended within the range that does not impede the purpose of the present invention. Alternatively, non-precipitating or organic additives such as antioxidants, heat stabilizers, lubricants, ultraviolet absorbers, nucleating agents, etc. may be added to the extent that they are normally added. Further, in addition to inert particles, internally precipitated particles may be contained. The internally precipitated particles in the present invention are particles produced by the combination of a polyester component and at least one of a calcium compound, a magnesium compound, and a lithium compound added during polyester polymerization.

The internally precipitated particles of the present invention may contain elemental phosphorus and trace amounts of other metal components, within a range that does not impede the purpose of the present invention.
For example, zinc, cobalt, antimony, germanium, titanium, etc. may be included.

The film of the present invention is a film in which the above composition is biaxially oriented. An unstretched film is not preferred because it has poor slip properties and abrasion resistance. Although the degree of biaxial orientation is not particularly limited, the scratch resistance is better when the Young's modulus of the film, which represents the degree of molecular orientation, is 350 kg/mm2, preferably 400 kg/mm2 or more in both the longitudinal direction and the width direction. Therefore, it is particularly desirable.

In the film of the present invention, in the concentration distribution curve of inert particles measured from the surface of at least one side of the film to a depth of 3000 nm, the depth (distance from the surface) Anm at which the particle concentration is 10 times the surface layer particle concentration value and the surface layer The relationship between the particle concentration value and the depth Bnm at which the particle concentration is the same (B>A, that is, B is a point deeper than A) is expressed by the following formula (i), preferably (io), and more preferably (i''). It is necessary to be satisfied.

10≦B-A≦1500... (1) 30≦B-
A≦1300... (io)50≦B-A≦10
00 ... (i”) Both sides of the film and thing B-A
If it is smaller than the above range, or conversely if it is larger than the above range, the scratch resistance will be poor, so it is not preferable. In addition, the depth is A
If there is no point in the deeper region up to 3000 nm where the particle concentration is the same as the surface layer particle concentration value, B = 300.
0 nm and 76° In the inert particle concentration distribution curve measured from the surface of at least one side of the film to a depth of 3000 nm, the depth (distance from the surface) where the particle concentration is 10 times the surface particle concentration value ) Anm must satisfy the following formula (ii), preferably (ii'), more preferably (ii'').

5≦A≦500 ... (ii) 5≦A≦250
... (i-bi) 10≦A≦100 ...
(i'') If the depth (distance from the surface) Anm at which the particle concentration is 10 times the surface layer particle concentration value is smaller than the above range, or conversely if it is larger than the above range, the scratch resistance will be poor, which is not preferable.

The film of the present invention has better scratch resistance when the ratio of the 10-point average roughness RZ to the maximum height Rt of the surface satisfying the above particle concentration distribution structure, RZ/Rt, is 0.85 or more. Particularly desirable.

The film of the present invention has better scratch resistance when the ratio of the center line average roughness Ra to the maximum height Rt of the surface satisfying the above particle concentration distribution structure, Rt/Ra, is 9.0 or less, particularly 8.0 or less. This is particularly desirable since it provides even better results.

In addition, the ratio of the center line depth Rp to the maximum height Rt of the surface satisfying the above particle concentration distribution configuration, R1/Rp, is 1.4 to 2.0.
1 is particularly desirable in the case of 1.6 to 2.0 because the scratch resistance becomes even better.

The film of the present invention has an average protrusion spacing sm of 6 μm or less, preferably 4.5 μm on the surface that satisfies the above particle concentration distribution structure.
It is particularly desirable that the scratch resistance is less than m because the scratch resistance becomes even better.

The film of the present invention is particularly desirable when the average protrusion height of the surface satisfying the above particle concentration distribution structure is in the range of 10 to 200 nm, since the scratch resistance becomes even better.

The film of the present invention has a content of low molecular components (such as cyclic 3M in polyester) within a range of 2000 nm from the surface of the surface satisfying the above particle concentration distribution structure of 0.6.
It is particularly desirable that the amount is less than 0.5% by weight, preferably less than 0.5% by weight, since the scratch resistance will be even better.

The film of the present invention has an oxygen permeability coefficient of 400 C/1 when converted to a thickness of 15 μm in the range up to the depth of B in the above formula (i) on the surface satisfying the above particle concentration distribution structure.
m2-24 hours-atm or less, preferably 30cc/m
The case of 2 to 24 hours atm is particularly desirable because the scratch resistance becomes even better.

The type of magnetic layer of the magnetic recording medium of the present invention is not particularly limited, and known magnetic materials such as γ-iron oxide, CO-containing iron oxide, chromium dioxide, iron, cobalt, or alloys thereof may be used. However, especially iron, cobalt,
The effects of the present invention are particularly effective in the case of so-called metal coating type magnetic layers made of alloys thereof and organic binders, and metal thin film type magnetic layers formed by methods such as vapor deposition and sputtering without using substantially organic binders. This is especially desirable because it becomes noticeable. Further, the type of binder is not particularly limited, and vinyl chloride/vinyl acetate copolymer, polyvinyl butyral, polyurethane, etc. can be used. A back coat layer may or may not be present, but if a back coat layer is provided, vinyl chloride, vinyl acetate,
Those mainly based on known binders such as vinyl alcohol and copolymers thereof, polyurethane, and cellulose derivatives can be used.

Although the thickness of the magnetic layer is not particularly limited, a thickness of 3 μm or less is particularly desirable because the effects of the present invention are particularly noticeable.

The thickness when providing a back coat layer is not particularly limited, but it is 0.05 to 2.5 μm, particularly 0.1 to 1.5 μm.
This is particularly desirable since the scratch resistance will be even better.

The heat-sensitive transfer layer of the heat-sensitive transfer material 1 of the present invention is not particularly limited, and known ones can be used, but it is basically a composition consisting of a colorant and a binder.

As the coloring agent, dyes, organic and/or inorganic pigments, etc. can be used. Further, as the binder, known binders such as carnauba wax can be used.

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

First, inert particles can be incorporated into a given thermoplastic resin by adding them before, during, or after polymerization, but in the case of polyester, they are mixed and dispersed in the diol component in the form of a slurry. A method of adding at least one element is effective in satisfying the particle concentration distribution structure of the present invention. In addition, as a method for adjusting the particle content, a method is used in which a highly concentrated master polymer is diluted during film formation, and the melt viscosity of this master polymer is higher than that of the thermoplastic resin to be diluted, preferably 500 It is effective to make the cohesive energy density higher than poise and lower than that of the thermoplastic resin to be diluted by adjusting the components of the master polymer to satisfy the particle concentration distribution structure of the present invention.

After drying the thermoplastic resin pellet containing a predetermined amount of inert particles as necessary, it is fed to a known melt extruder and extruded into a sheet through a slit-like gouer.
It is cooled and solidified on a casting roll to form an unstretched film. In this case, a known film forming apparatus for laminated sheets (
For example, by using two or three extruders, two or three-layer manifolds, etc., an unstretched film with a two- to three-layer structure made of the same or different thermoplastic resins is produced, and at least one side of the film is biaxially oriented. Film thickness d (nm
) and the average particle diameter c (nm
> is 0.1≦d/C≦1゜5, and the thickness of the core layer is 0.03 to 0.5 μm, which is extremely effective in satisfying the particle concentration distribution configuration of the present invention. It is. Furthermore, setting the content of particles in the core layer to 3 to 45% by weight is extremely effective in satisfying the particle concentration distribution structure of the present invention. In addition, the particle concentration of the present invention is such that the melt viscosity of the thermoplastic resin used for the core layer (surface layer) is set higher by about 500 poise, preferably about 1000 poise, than the melt viscosity of the thermoplastic resin of other layers in contact with it. This is extremely effective in satisfying the distribution configuration. Further, the method of installing a static mixer and a gear pump in the polymer flow path of the thermoplastic resin of the core layer is extremely effective in satisfying the particle concentration distribution configuration of the present invention without causing stretching breakage. Furthermore, keeping the crystallization parameter ΔTCCI of the thermoplastic resin in the core layer smaller than 8TCq of the thermoplastic resin in other layers in contact with it, preferably smaller than 10°C, satisfies the particle concentration distribution structure of the present invention. It is extremely effective.

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, using a sequential biaxial stretching method in which stretching is performed first in the longitudinal direction and then in the width direction, the stretching in the longitudinal direction is carried out at 10°C below the glass transition point of the thermoplastic resin.
1000 to 100 in the range of low temperature to 10℃ higher temperature
A method carried out at a relatively low stretching speed of 0.00%/min is extremely effective in satisfying the particle concentration distribution structure of the present invention. The stretching method in the width direction is 10% lower than the glass transition point of the thermoplastic resin of the core layer under high humidity of 50% RH or higher.
A method of stretching in a temperature range from 10.degree. C. lower to 30.degree. C. higher than the glass transition point is extremely effective in satisfying the particle concentration distribution structure of the present invention. The stretching speed in the width direction is
ioo.

It is effective to increase the stretching speed in the longitudinal direction to 20,000%/min to satisfy the particle concentration distribution structure of the present invention. The stretching ratio is preferably 3 to 5 times in both the longitudinal and width directions. Next, this stretched film is heat treated, and a known method can be used. It should be noted that even in the case of a single layer (complaint film), the present invention can be achieved by adjusting the melt viscosity and cohesive energy density of the particle master polymer, introducing a gear pump or a study mixer into the polymer flow path, strictly adjusting the stretching conditions, or using solution casting. Although it is possible to satisfy the particle concentration distribution structure, there are problems with stability, reproducibility, etc., and this is not preferred industrially.

A magnetic recording medium is obtained by forming a magnetic layer on at least one side of the above biaxially oriented film. That is, it can be manufactured by applying a paint containing a magnetic substance, drying, and then calendering it, or by forming a magnetic total refraction thin film by vapor deposition or sputtering. Further, if necessary, a back coat layer is formed by applying a solution having a predetermined composition and drying it. The back coat layer may be formed at any time, such as before the magnetic layer is formed, after the magnetic layer is formed and before calendering, after calendering, or during the curing process.

The heat-sensitive transfer layer 1 is prepared by hot-melt coating a prescribed heat-sensitive transfer agent on one side of the biaxially oriented thermoplastic resin film, or by dispersing or dissolving it in a solvent.
Although it is manufactured by applying a liquid, there is no particular limitation on the manufacturing method.

[Effects of the Invention] The present invention provides a film and a material made from the same that do not get scratched even when running at high speeds because the particle concentration on at least one side of the film is in a special state.

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

(1) Concentration of inert particles 5 (depth profile) Using a secondary ion Mffi analyzer (SIMS), we measured the highest concentration of particles in the film from the surface layer to a depth of 3000 nm. The concentration ratio (M+/C'') of the contributing element and the carbon element of the thermoplastic resin is taken as the particle concentration, and analysis is performed in the thickness direction from the surface to a depth of 3000 nm.

In the surface layer, the particle density is low due to the interface called the surface, and the particle concentration increases as the distance from the surface increases. In the case of the film of the present invention, the particle concentration once reached a maximum value begins to decrease again. Based on this y2 degree force distribution line, point A (distance from the surface) shows a particle concentration 10 times that of the surface layer particle concentration, and a point where the particle concentration, which had once increased, decreased to the same value as the surface layer particle concentration. Find B (distance from the surface). Of course,
B is at a deeper position than 8.

The conditions are as follows.

(1) Measuring device Secondary ion mass spectrometer (SIMS) West Germany, ^TO former A? ! 1'tAA-DID8300
(2) Measurement conditions Primary ion species: 02+ Primary ion acceleration voltage = 12V Primary ion current: 200nA Raster area: 400μm mouth analysis area 2 gates 30% Measurement vacuum: 5. Ox 10'TorrE-GLI
N: 0.5KV-3, OA, depth 30 from the surface layer
If the particles in the 00 nm range are organic polymer particles, it is difficult to measure them using SIMS, so the edge leg method from the surface, the sectioning method, XPS (X-ray photoelectron spectroscopy), IR (infrared spectroscopy), etc. The same depth profile as above is measured, and the depths of A and B are determined.

(2) Plasma low-temperature ashing process (
For example, the particles are removed using a printer (Model PR-503 manufactured by Yamato Kagaku Co., Ltd.) to expose the particles. The processing conditions are selected so that the polyester is incinerated but the particles are not damaged. SE this
Observe with an X (scanning electron microscope) and use an image analyzer (for example, Cambridge Instruments QTM900) to capture the image of the particles (shade of light created by the particles).
The following several fU process is performed with the number of particles being 5000 or more by changing the I2 dormitory location, and the number average diameter obtained thereby is taken as the average particle diameter.

D-ΣD+ /N Here, Di is the circle-equivalent diameter of the particles, and N is the number of particles.

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

<4) Crystallization parameter ΔTCg PerkinElmer DSC (differential scanning thermal m, Tf)
It was measured using type III. The DSC measurement conditions are as follows. That is, a sample of 10 m (10 m) was set in a Dsc device, melted at a temperature of 300'C for 5 minutes, and then rapidly cooled in liquid nitrogen.The rapidly cooled sample was heated at a rate of 10'C/min until the glass transition point TCI Detect.

The temperature was continued to be gradually raised, and the exothermic peak temperature of crystallization from the glass state was defined as the cold crystallization temperature Tcc.

The temperature was continued to rise gradually, and the heat of fusion was determined from the melting peak. Here, the difference between TCC and the density (Cc - Tg) is defined as the crystallization parameter 8TCg.

(5) Average height of surface protrusions Two-detector scanning electron microscope [ESM-3200,
manufactured by Elionix Co., Ltd.] and a cross-sectional measuring device [PMS-1,
The height of the protrusions was measured using an image processing device [I BAS2000, Carl Zeiss K.K.
[Manufacturer] and reconstructs the image of the film surface protrusions on an image processing device. Next, a circular equivalent diameter is determined from the area of each protrusion obtained by binarizing the protrusion portion using this surface protrusion image, and this is taken as the average diameter of the protrusion. Furthermore, the highest value among the binarized 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 height distribution of the measured projections was assumed to be a normal distribution and approximated by the least squares method. Furthermore, the magnification of a scanning electron microscope is 1000 to 800.
Select a value between 0x.

(6) Center line average surface roughness Ra, 10 point average roughness R
z, center line depth Rp, maximum height Rt, protrusion interval m Measured using a high precision thin film step measuring instrument ET-10 manufactured by Koita Research Institute. The values are as follows, and the average value of 20 measurements was taken as the value.

・Stylus tip radius: 0.5μm ・Stylus part: 5mC1 ・Measurement length = 1mm ・Cutoff 1 shift: o, oamm The definitions of Ra, RD, Rt, and Sm are, for example, ""Method for Measuring and Evaluating Surface Roughness" (General Technology Center, 1983).

(7) Young's modulus: 25% using an Instron type tensile tester according to the method specified in Jl5-Z-1702.
Measurement was performed at °C and 165% RH.

(6) 290°C1 shear rate 2 using a melt viscosity enhancement type flow tester
Measured at 00sec-'.

(9) Sphericity Average value of the major axis of each particle in the measurement of (1) above /
It is the ratio of the average value of the short axis.

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

Major axis=Σ[)li/N Minor axis=ΣD2i/N [)li, [)2i are the major axis (maximum diameter) and minor axis (shortest axis) of each individual particle, respectively, and N is the total number.

(+ω Relative standard deviation of particle size Standard deviation σ(-f(
The value obtained by dividing Σ (Di-D>2/N) ) by the average diameter (σ
/D>.

(11) Pulverize the sample polymer containing low molecular weight components in a predetermined depth range and use a Soxhlet extractor to extract the sample under reflux for 24 hours using chloroform as a solvent.
Perform time extraction. The ratio (wt%) of the weight of the extract obtained by evaporating chloroform to the weight of the original sample (1 liter) was taken as the low molecular component content.

(2) Scratch resistance 1/2 inch wide tape film (or magnetic recording medium) or thermal transfer ribbon slit into a 3 mm wide tape shape on a guide pin with an external diameter of 5 mm in an atmosphere of 20'C relative humidity 60% The angle θ=π/2(ra
d) After running 30 times at a speed of 1000 m/min with tension T1=200C1, the film surface was aluminum-deposited, and the number of scratches, width, and state of white powder generation were observed using a differential interference microscope. . Scratch resistance: 4, with no scratches and almost no white powder generation; scratch resistance: 3, with less than 3 scratches and almost no white powder generation; width: 3 to 10 scratches Scratch resistance = 2 for those with large scratches and white powder generation; scratch resistance = 2 for those with 10 or more scratches and large width, and scratch resistance: It was determined to be 1. If the scratch resistance is 4 or 3, it can be used practically without any problem.

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

Examples 1 to 5, Comparative Examples 1 to 4 Silica particles derived from colloidal silica with different average particle sizes, polyethylene terephthalate containing divinylbenzene/styrene copolymer crosslinked particles, polyethylene-2,
6-Naphthalate was adjusted (melt viscosity changed). These master polymers and polyethylene terephthalate (melt viscosity 21500 voids) containing substantially no inert particles
Or polyethylene-2,6-naphthalate (molten viscosity: 4000 voids) was mixed to obtain a predetermined particle concentration (thermoplastic resin A). Various thermoplastic resins (B) were added to this thermoplastic resin using an extruder 1. , fed to extrusion R2, 290
These polymers were melted at 100°C and laminated in confluence, then wound around a casting drum with a surface temperature of 30°C using electrostatic casting, and cooled and solidified to produce a 3-layer unstretched film. . Further, the discharge 1 of each extruder was adjusted to adjust the total thickness and the thickness of the thermoplastic resin A layer. This unstretched film was stretched 4.0 times in the longitudinal direction at different temperatures. This stretching was carried out using a difference in peripheral speed between two sets of rolls, and the stretching speed was 2000%/min. This axially stretched film was stretched 4.5 times in the width direction using a stenter while changing the stretching speed and humidity atmosphere, and then heat-treated at 200'C for 5 seconds under a constant length. 19 for axially oriented laminated film. The parameters of the invention for these films are the first
As shown in the table, if the parameters of the present invention were within the range, the scratch resistance was good as shown in Table 1, but if not, a film satisfying the scratch resistance could not be obtained. Ta.

Examples 4-5, Comparative Examples 5-8 Polyethylene terephthalate and polyethylene-2,6-naphthalate containing spherical silica caused by colloidal silica with different average particle sizes were adjusted (melt viscosity changed)
. These master polymers and polyethylene terephthalate (melt viscosity: 150
0 poise) or polyethylene-2,6-naphthalate (melt viscosity: 4000 poise) was mixed to obtain a predetermined particle concentration (to thermoplastic↑1 resin).This thermoplastic resin A was mixed with 0.1% by weight of spherical silica particles. An unstretched film with a two-layer structure was prepared by laminating various thermoplastic resins (B) with different lamination thicknesses.This unstretched film was stretched 4.0 times in the longitudinal direction at different temperatures. This stretching was carried out using a difference in peripheral speed between two sets of rolls, and the stretching speed was 2000%/min.

This axially stretched film was stretched 4.5 times in the width direction using a stenter while changing the stretching speed, humidity, and atmosphere, and was then heat-treated at 200'C for 5 seconds under a constant length to reduce the total thickness. A 12 μm biaxially oriented laminated film was prepared. A CO/Ni alloy (Co/N 1=75/25 weight ratio) was deposited to a thickness of 180 nm on the thermoplastic resin entry surface of these films by electron beam evaporation.
A magnetic thin film was formed by oblique vapor deposition (minimum incident angle: 500). Apply the following composition on the opposite side to a thickness of 0.5 μm.
A bank coat layer of m was formed.

(Back coat composition) - Polyester (Toyobo Vylon 200 > 80 parts by weight Nitrocellulose 20 parts by weight - Carbon black 80 parts by weight - Silica particles (average particle size 0.01 μm) (50 parts by weight relative to organic binder) - Mejiru Edge The parameters of the present invention for this magnetic tape are shown in Table 2, and if the parameters of the present invention are within the range, the magnetic surface The scratch resistance was good as shown in Table 2, but otherwise no film was found to satisfy the scratch resistance.

Example 6, Comparative Examples 9 to 12 After corona treatment was applied to one side of the film of Example 1 and the films of Comparative Examples 1 to 4, 30 parts of carnauba wax, 35 parts of paraffin wax, and oil blackened IBB (
A mixture of 5 parts of oil-soluble dye manufactured by Orient Kagaku Kogyo Co., Ltd., 25 parts of carbon black, and 5 parts of lanolin was hot-melt coated to a thickness of 4 μm, and a heat-sensitive transfer film was coated.

This film was slit to a width of 8 mm to obtain a thermal transfer ribbon. The parameters of the present invention for this thermal transfer ribbon are as shown in Table 3, and when the parameters of the present invention were within the range, the scratch resistance of the film surface was good as shown in Table 3. Otherwise, a film with satisfactory scratch resistance could not be obtained.

Claims (4)

[Claims] (1) A film whose main component is a composition consisting of a thermoplastic resin and inert particles, and in the concentration distribution curve of inert particles measured from the surface of at least one side of the film to a depth of 3000 nm, the particle concentration is Depth (distance from the surface) where the surface layer particle concentration value is 10 times Anm and depth Bnm where the particle concentration is the same as the surface layer particle concentration value (B>A)
A biaxially oriented thermoplastic resin film, characterized in that the relationships satisfy the following formulas (i) and (ii). 10≦B-A≦1500...(i) 5≦A≦500...(ii) (2) The biaxially oriented thermoplastic resin film according to claim (1), wherein the inert particles have a sphericity of 1.6 or less. (3) A magnetic recording medium characterized in that a magnetic layer is provided on at least one side of the biaxially oriented thermoplastic resin film according to claim (1) or (2). (4) A heat-sensitive transfer material, characterized in that a heat-sensitive transfer layer is provided on one side of the biaxially oriented thermoplastic resin film according to claim (1) or (2).