JPH04105935A - Biaxially oriented thermoplastic resin film - Google Patents

Abstract

PURPOSE:To obtain the title film hardly damaged in a high speed process, excellent in scratch resistance and generating no lowering of image quality at the time of dubbing by specifying the mean particle size and content of a spherical calcium carbonate particle. CONSTITUTION:A biaxially oriented thermoplastic resin film is constituted of a film (B-layer) based on a thermoplastic resin B and the film (A-layer) based on a thermoplastic resin A containing spherical calcium carbonate particles provided to at least the single surface of the B-layer and the mean particle size of the spherical calcium carbonate particles is set to 0.2-5 times the thickness of the A-layer and the content of the spherical calcium carbonate particles in the A-layer is set to 0.1-20wt.% and the thickness of the A-layer is set to 0.01-3mum. By this method, mechanical characteristics become well and scratch resistance and dubbing resistance become more well.

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, a magnetic layer coating process for magnetic media use, a calendering process, or a soft tape etc. by dubbing the finished videotape 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 provides a film containing thermoplastic resin B as a main component (B
A biaxially oriented laminated film consisting of a film (A layer) mainly composed of a thermoplastic resin A containing spherical calcium carbonate particles provided on at least one side of the biaxially oriented laminated film, wherein the average of the spherical calcium carbonate particles is The particle size is 0.2 to 5 times the thickness of layer A, the content of the spherical calcium carbonate particles in layer A is 0.1 to 20% by weight, and the thickness of layer A is 0.0.
The main feature is a biaxially oriented thermoplastic resin film characterized by a thickness of 1 to 3 μm.

The film of the present invention is a film made of thermoplastic resin B (
This is a biaxially oriented laminated film in which a film made of thermoplastic resin A (layer A) is laminated on at least one side of layer B). By doing so, not only the mechanical properties are improved, but also the scratch resistance and dubbing resistance are further improved, which is extremely desirable. Here, the thermoplastic resins A and B may be the same type or different types.

Thermoplastic resin A constituting layer A of the present invention is not particularly limited to polyester, polyolefin, polyamide, polyphenylene sulfide, etc., but particularly polyester, ethylene terephthalate, ethylene α, β-bis(2-chlorophenoxy)ethane, etc. It is preferable to use at least one structural unit selected from -4,4'-dicarboxylate and ethylene 26-naphthalate units as the main constituent, since the scratch resistance and dabbing resistance will be even better. Further, it is extremely desirable that the thermoplastic resin A constituting the present invention be crystalline or optically anisotropic when melted, since this provides even better 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 1508C 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. Further, a polyester containing ethylene terephthalate as a main component is particularly desirable because it has even better dubbing resistance and scratching/soiling resistance. In addition, within the range that does not impede the present invention,
Two or more types of thermoplastic resins may be mixed, or a copolymer may be used.

The thermoplastic resin A of the present invention must contain spherical calcium carbonate particles having a sphericity of 1.5 or less. This further improves scratch resistance and dubbing resistance. Furthermore, it is particularly desirable that the crystalline form of the calcium carbonate particles contained in the thermoplastic resin A has a vaterite structure, since this provides even better scratch resistance and dabbing resistance.

The calcium carbonate particles in the thermoplastic resin A of the present invention have a relative standard deviation of particle size of 0. A value of 7 or less, preferably 0.6 or less is desirable because scratch resistance and dubbing resistance become even better.

Furthermore, the size of the particles is such that the average particle size in the film is 0.00 mm of the thickness of the film (layer A). 2 to 5 times, preferably 0.
It is necessary that it be in the range of 5 to 5 times, more preferably 1.1 to 3 times. If the average particle size/A layer 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 specific particles are used in a specific film thickness/7 particle diameter ratio, scratch resistance and dubbing resistance are particularly good.

In addition, the average particle size (diameter) of calcium carbonate particles in thermoplastic resin A is 0.01 to 1 μm, particularly 0.02 to 0.5 μm.
A range of m is desirable because scratch resistance and dubbing resistance become even better.

The content of calcium carbonate particles in the thermoplastic resin A of the present invention is O in the A layer, 1 to 20% by weight, preferably 0.15% by weight.
It is necessary that the amount is 10% by weight, more preferably 0.2% to 8% by weight. If the content of the particles is less than the above range, or conversely if it is greater than the above range, the scratch resistance will be poor, so it is not preferable.

The A layer of the film of the present invention has a composition consisting of the above-mentioned thermoplastic resin A and particles 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. Organic additives such as additives, heat stabilizers, lubricants, and ultraviolet absorbers may be added to the extent that they are normally added.

As the thermoplastic resin B constituting the B layer, a crystalline polymer is desirable, and in particular, a crystalline polymer with a crystallinity parameter ΔTcg of 20 to 1
．． A temperature in the range of 00°C is desirable 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, examples of polyester include ethylene terephthalate and ethylene α.

β-bis(2-chlorophenoxy)ethane-4,4'-
It is desirable to have at least one type of structural unit selected from dicarboxylate and ethylene 2,6-naphthalate units as the main constituent because the dubbing resistance is 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 particles in the film (B layer) made of thermoplastic resin B, but if the average particle size is 0.01-
~2 μm 1 Particularly 0.02 to 0.5 μm particles are 0.001 to 0.5% by weight, especially 0.005 to 0.5% by weight of the B layer.
When the content is 3% by weight, not only the scratch resistance becomes even better, but also the winding appearance of the film becomes better, which is extremely desirable.

The type of particles in the thermoplastic resin B of the present invention is not particularly limited, but alumina silicate, silica in a state where primary particles are aggregated, internally precipitated particles, etc. are not preferred, and substantially spherical particles due to colloidal silica Silica particles, particles made of crosslinked polymers (for example, crosslinked polystyrene), or the above-mentioned spherical calcium carbonate particles are particularly desirable because they provide even better scratch resistance and dabbing resistance.

At this time, the types of particles contained in thermoplastic resins A and B,
The sizes 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.

The film of the present invention has the above A layer on at least one side of the B layer.
It is a film made of laminated layers and further biaxially oriented. - Axial or non-oriented films are not preferred because they have poor scratch resistance. The degree of this orientation is not particularly limited, but the Young's modulus, which is a guideline for the degree of molecular orientation of polymers, is 350ks in both the longitudinal and width directions.
/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 kB/mm2.

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, if the thermoplastic resin is a crystalline polyester and the total reflection Raman crystallization index of the surface of the A layer is 20 cm' or less, preferably ]-8 cm' or less, and further 17 cm-' or less, scratch resistance and dubbing resistance are obtained. This is highly desirable since the properties are even better.

The thickness of the film (A layer) made of the thermoplastic resin A of the present invention is 0.01-3 μm1, preferably O102-], μ
m, 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.

The average protrusion height on the surface of the film (A layer) made of thermoplastic resin A of the present invention is 5 to 500 nm, preferably 10 to 500 nm.
A range of 300 nm, more preferably 1-5 to 200 nm, is particularly desirable because scratch resistance and dubbing resistance are even better.

It is particularly desirable that the average distance between the protrusions on the surface of the film (layer A) made of thermoplastic resin A of the present invention is 6 μm or less, preferably 4 μm or less, 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 optically anisotropic in melting. However, in the case of a melting method film, if the crystallization parameter ΔTcg is 25 to 65°C. This is particularly desirable since it provides even better scratch resistance.

In addition, when the thermoplastic resin A is polyester, it is particularly desirable that the refractive index of the thermoplastic resin A surface in the thickness direction is 1-05 or less, since the scratch resistance and dubbing resistance will be even better. Further, it is particularly desirable that the film has an intrinsic viscosity of 0.60 or more, particularly 0.65 or more, since the scratch resistance will be even better.

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

First, as a method for incorporating 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 polymerized with a predetermined dicarboxylic acid component. It is effective to obtain a film having the 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 the particles, the crystallization parameter ΔTcg can be adjusted to 40 to 6.
The method of keeping the temperature within the range of 5°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.

In addition, as a method for incorporating particles into a thermoplastic resin, the present invention also includes a method in which the particles are mixed with the thermoplastic resin in the form of an aqueous slurry, and kneaded using a vent type twin-screw extrusion machine to knead the particles into the thermoplastic resin. It is extremely effective in obtaining films with a range of thickness and average particle size relationship and content.

One way to adjust 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 particles during film formation to adjust the particle content. It is valid.

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.

Thermoplastic resin A composition and thermoplastic resin B (A and B may be of the same type or different types), which are dried as required, are pellets containing a specified amount of particles by the above method, and then extruded using a known method for melt lamination. The thermoplastic resin is fed into a machine, extruded into a sheet through a slit die at a temperature above the melting point and below the decomposition point of the thermoplastic resin, and cooled and assimilated on a casting roll to form an unstretched film. That is, thermoplastic resins A and B are laminated using two or three extruders, a two or three layer manifold or a merging block, two or three layers of sheets are extruded from a die, and the sheets are cooled with a casting roll. Make an unstretched film. In this case, a method of installing a static mixer or a gear pump in the polymer flow path to the thermoplastic resin 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, it is possible to set the melting temperature of the extruder on the thermoplastic resin A side 10 to 20'C higher than on the thermoplastic resin B side to maintain the relationship between the thickness and average particle size within the range of the present invention, the content, and the orientation state within the desired range. Effective for obtaining film. Furthermore, when extruding into an unstretched film, the ratio of the die slit gap/unstretched film thickness is set in the range of 6 to 25, preferably 8 to 20, to achieve the relationship between the thickness and the average particle size within the range of the present invention. 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 carried out at a magnification of 0 to 6.5 times is effective for obtaining a film having the 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, the stretching ratio in the longitudinal direction is suitably 1.0 to 1-11 times. The stretching temperature in the longitudinal direction varies depending on the type of thermoplastic resin, and cannot be generalized, but it is usually at a temperature of 50 to
It is effective to set the film to 1-300C, and to set it higher in the second and subsequent stages, in order to obtain a film having the relationship between thickness and average particle size, the content, and the orientation state within the desired range of the present invention. The 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 20000
%/min, and the temperature is preferably in the range of 80 to 160°C. At this time, the stretching temperature in the longitudinal and lateral directions must be set based on thermoplastic resin A. Next, this stretched film is heat treated. The heat treatment temperature in this case is 1-70~20
0°C, especially 1°70~190°01 hour is 0. 5-6
A range of 0 seconds is preferred. Furthermore, in the heat treatment process of the two-layer laminated film, the temperature of the hot air blown onto the thermoplastic resin A layer is 3 to 20°C lower than that of the thermoplastic resin B layer. , is effective in obtaining a film with a desired range of orientation states.

[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) 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, Di is the circle-equivalent diameter of the particles, and N is the number of particles.

(2) Sphericity of particles In the measurement of (1) above, (major axis/minor axis) of individual particles
is the average value of the ratio of

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

Sphericity = Σ (D li / D 2i) / ND 11
% D 2 + is the long axis (maximum diameter) of each individual particle
, the shortest axis (shortest axis), and N are the total number.

(3) Relative standard deviation of particle size Standard deviation σ(-Σ(Σ
(Di - D) 2/N) ) divided by the average diameter (
It was expressed as 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 ΔTcg, heat of fusion was measured using a differential scanning calorimeter. The measurement conditions are as follows. That is, 10 mg of the sample 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. The temperature of this rapidly cooled sample is raised at a rate of 1-0°C/min, and the glass transition point Tg 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 165% RI-T. The biaxial orientation of the polymer is such that the absolute value of (Nl - N2) is 0.07 or less, and N3 / [: ( Nl
+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 using Iob in-Yv
The total reflection Raman spectrum was measured using a Ramanor U-1, OOO Raman system manufactured by On, and for example, in the case of polyethylene terephthalate, it
Polarization measurement ratio of band intensity ratio of (skeletal vibration of benzene ring) and 1.730 cm-' (stretching vibration of carbonyl group) (
YY/XX ratio etc. Here, YY: detection of Mann light parallel to Y with the polarization direction of the laser set to Y; XX: detection of Mann light parallel to X with the polarization direction of the laser set to X) corresponds to molecular orientation. 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 the width direction, and based on their absolute values, differences, etc. In addition, 1- which is the stretching vibration of carbonyl group
The half width of 730 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
ting System (Hamamatsu C12
30) (supply 1600V) ■Measurement conditions 5LIT ] 000μm LASER10
0mW GATE TIME 1.0secSCAN
5PEED 12cm-'/min
SAMPLING INTERVAL 0.2 cm-'
REPEAT TIME 6 (7) Average height of surface protrusions An image of the measured value of the height of protrusions when scanning with the height of the flat surface of the film surface set to O using a two-detector force-type scanning electron microscope and a cross-section measuring device. The film is sent to a processing device and an image of the film surface protrusions is reconstructed on the 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 a scanning electron microscope is 1. ．． Select a value between 000 and 10.000 times.

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

(9) Intrinsic viscosity [η] (unit: dl/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] 10K[η]2 ・With a smile, η, 1,
-(Solution viscosity/solvent viscosity)-1, C is the weight of dissolved polymer per 100ml of solvent (g/100ml. Usually 1-.2
), K is the Huggins constant (assumed to be 0,34-3). Also,
Solution viscosity and solvent viscosity were measured using an Ostwald viscometer.

(10) Crystal form of calcium carbonate Particles were separated in the same manner as in (1) above, and the crystal structure of the particles was measured by ordinary X-ray diffraction.

(11) A scratch-resistant film slit into a tape with a width of 1/2 inch is run on a guide pin (surface roughness: 100 nm in Ra) using a tape running tester (running speed 1.000m/min, 10 passes, winding angle =
60°, running tension crab 65g).

At this time, the scratches in the film were observed under a microscope, and the width was 2.
Less than 2 scratches of 5 μm or more per width of the tape were determined to be excellent, 2 or more and less than 10 scratches were determined to be good, and 1-0 or more scratches were determined to be poor. Excellent is desirable, but good is still usable for practical purposes.

(1-2) A magnetic paint having the following composition is applied to a dubbing-resistant film using a gravure roll, magnetically oriented, and dried. Furthermore, a small test calender device (steel roll/nylon roll, 5
), the temperature is near 00C.

Linear pressure: 7 after calendering at 200 kg/cm
Cure for 0°0148 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 form a VTR cassette tape.

(Composition of magnetic paint) - Co-containing iron oxide - 1,00 parts by weight - Vinyl chloride/vinyl acetate copolymer = 1.0 parts by weight - Polyurethane elastomer: 1-0 parts by weight - Polyisocyanate) - 5 parts by weight lecithin
1-part by weight methyl ethyl ketone
= 75 parts by weight methyl isobutyl ketone
= 75 parts by weight・Toluene =
75 parts by weight / Carbon black 2 parts / 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 playback signal was measured using a color video noise measuring device. The chroma S/N was measured and given 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 (A-B
) was less than 3 dB, the dubbing resistance was judged as excellent, 3 dB or more and less than 5 dB as good, and 5 dB or more as 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 slurries containing calcium carbonate having different average particle sizes and crystal structures were prepared, and after heat-treating the ethylene glycol slurry at 1900C for 15 hours, transesterification with dimethyl terephthalate was performed. After the reaction, polycondensation was performed to produce polyethylene terephthalate pellets containing 0.05 to 8% by weight of the particles. At this time, the polycondensation time was adjusted to give an intrinsic viscosity of 0.66 (thermoplastic resin A).
. Further, polyethylene terephthalate having an intrinsic viscosity of 0.62 and substantially free of particles is produced by a conventional method,
Thermoplastic resin B was used. Each of these polymers is
Dry under reduced pressure at 80°C for 6 hours (3T).

rr) I did. Thermoplastic resin A is supplied to extruder 1 29
Thermoplastic resin B is melted at 0°C, and further, thermoplastic resin B is supplied to extruder 2, melted at 285°C, these polymers are merged and laminated in a merging block (feed block), and the surface temperature is adjusted using an electrostatic casting method. It was wound around a casting drum at 25°C and cooled and solidified to produce an unstretched film with a two-layer structure. The total thickness and the thickness of the thermoplastic resin A layer were adjusted by adjusting the discharge amount 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 five stages with a difference in peripheral speed between two sets of rolls. This -axially stretched film was stretched at a stretching speed of 2 using a stenter.
．． Stretched 4.0 times in the width direction at 100%/min at 100°C, heat treated at 2100C for 5 seconds under constant length, total thickness 1-5 μm 1 Thermoplastic resin A layer thickness 0.2-7 .5μm
A biaxially oriented laminated film was obtained. The parameters of the present invention for these films are shown in Table 11, 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 utilizes a thermoplastic resin containing specific particles by devising a manufacturing method to produce a laminated film in which the relationship between particle size and film thickness, content, and film thickness are set within specific ranges. As a result, a film with excellent scratch resistance and dubbing resistance was obtained.

Although the use of the film of the present invention is not particularly limited, it is particularly useful as a base film for magnetic recording media, where scratches on the film surface during processing are particularly problematic in terms of processing and product performance. In addition, for films of the present invention with a two-layer structure, the thermoplastic resin side A is the running surface (for magnetic recording media, the surface is not coated with a magnetic layer, and for other uses, it is the surface that is subjected to processing such as printing or coating with other coating materials). It is preferable to use it as a surface that is not exposed.

In addition, the present invention is a film made by direct composite lamination without any operations such as coating during the film-forming process, and compared to laminated films made during the film-forming process or by subsequent coating, the outermost layer has two molecules. Since it is axially oriented, it has far superior properties other than those described above, such as surface abrasion resistance, and is advantageous in terms of cost and quality stability.

Claims (5)

[Claims] (1) Film whose main component is thermoplastic resin B (B layer)
and a film (layer A) mainly composed of thermoplastic resin A containing spherical calcium carbonate particles provided on at least one side thereof, the film having an average particle diameter of the spherical calcium carbonate particles. is the thickness of A layer 0.
2 to 5 times, the content of the spherical calcium carbonate particles in layer A is 0.1 to 20% by weight, and the thickness of layer A is 0.01 to 20% by weight.
A biaxially oriented thermoplastic resin film having a thickness of 3 μm. (2) B layer contains particles with an average particle size of 0.01 to 2 μm.
Claim characterized in that it contains 01 to 0.5% by weight (
1) The biaxially oriented thermoplastic resin film according to item 1). (3) The biaxial orientation heat according to claim (1) or (2), wherein the relative standard deviation of the particle size of the spherical calcium carbonate particles contained in the thermoplastic resin A is 0.7 or less. Plastic resin film. (4) The biaxially oriented thermoplastic resin film according to any one of claims (1) to (3), wherein the crystalline form of the spherical calcium carbonate particles contained in the thermoplastic resin A is a vaterite structure. . (5) Thermoplastic resin A is crystalline polyester, and the total reflection Raman crystallization index of the A layer surface is 20 cm^-
Claims (1) to (4) characterized in that ^1 or less
The biaxially oriented thermoplastic resin film according to any one of the above.