JPH03150127A - Manufacture of biaxially stretched thermoplastic resin film - Google Patents

Abstract

PURPOSE:To obtain film excellent in resistances to scratching and dubbing by a method wherein specified amount of inert particles having specified particle diameters are added to thermoplastic resin so as to laminate films, which mainly consist of said thermoplastic resins after being biaxially stretched and heat-treated, to each other in order to realize film having specified thickness. CONSTITUTION:Film A, which mainly consists of thermoplastic resin A containing at least two kinds of inert particles having different mean particle diameters, is laminated at least to one side of film B mainly consisting of thermoplastic resin B. In this case, 2 - 20 wt.% of the inert particle having the minimum means particle diameter d1 is added to the thermoplastic resin A. The lamination is performed so as to bring the ratio t/d1 into 0.1 - 5, in which (t) is the thickness of the film, which mainly consists of the thermoplastic resin A and has been subjected to biaxially stretching and heat- treating. In the case that the particle diameter ratio (or ratio of the major axis to the minor axis of the particle) of the inert particle, which is added to the thermoplastic resin A and has mean particle diameter different from the inert particle just mentioned above, is 1.0 - 1.3 and the relative standard deviation of the particle diameters is 0.6 or less, more favorable resistances to scratching and dubbing result.

Description

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

[Prior Art 1] 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.).

[Problem to be Solved by the Invention 1] However, in the conventional biaxially oriented thermoplastic resin film described above, for example, a magnetic layer application for magnetic media use, a calendering process, or a soft tape by dubbing the finished video tape, 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 less susceptible to scratches (hereinafter referred to as "excellent scratch resistance") and less deterioration of image quality during dubbing (hereinafter referred to as "excellent dubbing resistance") especially during high-speed processes. It is an object of the present invention to provide a method for manufacturing an axially oriented thermoplastic resin film.

[Means for Solving the Problems] The present invention provides a film A containing at least two types of inert particles having different average particle diameters, the film A having the thermoplastic resin B as the main component. In the method for producing a biaxially oriented thermoplastic resin film laminated on at least one side of film B, when the smallest average particle size of the above inert particles added to thermoplastic resin A is d, the average particle size 2 to 20% by weight of inert particles having d The present invention relates to a method for producing a biaxially oriented thermoplastic resin film, characterized in that the film is laminated so that d is 0.1 to 5.

The thermoplastic resin A constituting the present invention is not particularly limited to polyester, polyolefin, polyamide, polyphenylene sulfide, etc., but particularly polyester, especially ethylene terephthalate, ethylene a, β-bis(2-chlorophenoxy)ethane-4,4'' It is preferable to use at least one structural unit selected from -dicarboxylate and ethylene 2,6-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 constituting the present invention be crystalline or optically anisotropic when melted, since this will further improve scratch resistance and dubbing resistance.

Here, crystallinity indicates that it is not so-called amorphous, and quantitatively, the cold crystallization temperature Tcc in the crystallization parameter is detected, and the crystallization parameter Δ
TcH is 150°C or less. Furthermore, the heat of fusion (change in enthalpy of fusion) measured with a differential scanning calorimeter is F.

It is extremely desirable to exhibit crystallinity of 5 csl/@ or more because scratch resistance and dubbing resistance become 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.

Regarding each inert particle having a different average particle size to be added to the thermoplastic resin A of the present invention, particles having a particle size ratio (longer diameter/breadth diameter of the particle) of 1.0 to 1.3, especially spherical particles. Particles are preferred because they provide even better scratch resistance.

In addition, scratch resistance is achieved when the relative standard deviation of the particle size of each of the inert particles added to the thermoplastic resin A of the present invention having different average particle sizes is 0.6 or less, preferably 0.5 or less. This is desirable because the dubbing resistance becomes even better.

The main chemical composition of the inert particles is not particularly limited, but in order to satisfy the above preferable particle characteristics, alumina silicate,
Silica particles in a state where primary particles are aggregated, internally precipitated particles, etc. are not preferable, and include substantially spherical silica particles caused by colloidal silica particles, particles made of crosslinked polymers (for example, crosslinked polystyrene), etc. Temperature at weight % weight loss (measured with a thermogravimetric analyzer in nitrogen. Heating rate: 20°C)
It is particularly desirable to use crosslinked polymer particles whose degree of crosslinking is increased to 380° C. or higher, since the scratch resistance and dabbing resistance will be even better.

In addition, in the case of a spherical silicate force resulting from colloidal silicate force, a substantially spherical silicate force produced by an alkoxide method with a low sodium content is particularly desirable because the scratch resistance becomes even better. However, other particles, such as particles of calcium carbonate, titanium dioxide, alumina, etc., can also be used satisfactorily with proper control of film thickness and average particle size. Note that the chemical compositions of the plurality of types of inert particles of the present invention may be different or the same.

In the method for producing a film of the present invention, it is necessary to add at least two types of the above-mentioned inert particles having different average particle diameters to the thermoplastic resin A constituting the film A. Here, it is particularly preferable that each of the inert particles having the respective average particle size satisfies the above-mentioned relative standard deviation of the particle size.

Among these inert particles having different average particle sizes, 0
．． The minimum average particle size among the inert particles added at 5% by weight or more is dl, and the maximum average particle size of all the inert particles added is d2. At this time, the ratio t/d of the thickness t of the film A mainly composed of the thermoplastic resin A and the average particle diameter d1,
must be in the range of 0.1 to 5, preferably 0.3 to 3, more preferably 0.4 to 1.0. If the ratio between the thickness t and the average particle diameter d of film A, which is mainly composed of thermoplastic resin A, is smaller than the above range, the scratch resistance will be poor; This is not preferable because it becomes defective.

The average particle diameter d1 of the inert particles added to the thermoplastic resin A is not particularly limited, but is 0.01 to 1 μm, particularly 0.02 to 1 μm.
A thickness in the range of 0.5 μm is desirable because scratch resistance and dubbing resistance become even better. The average particle diameter d2 of the inert particles added to the thermoplastic resin A is not particularly limited, but scratch resistance and dabbing resistance are better when it is in the range of 0.02 to 2 μm, particularly 0.05 to 1 μm. Therefore, it is desirable.

Furthermore, in terms of scratch resistance and dubbing resistance, the ratio t/d2 between the thickness t of the film containing thermoplastic resin A as a main component and the average particle diameter d2 of the inert particles is 0.05 to 3, and further 0.
A range of 1 to 2, more preferably 0.3 to 1.0 is desirable.

The amount of inert particles added to the thermoplastic resin A of the present invention having an average particle size d is 2 to 20% by weight, preferably 2% by weight.
It is necessary that the amount is 10% by weight, more preferably 3% to 8% by weight. Even if the amount of inert particles added is less than the above-mentioned range, or conversely, it is not preferable because the scratch resistance becomes poor. Note that the amounts of the inert particles of the present invention having different average particle diameters may be different or the same.

In the film obtained by the production method of the present invention, inert particles with small particle size variations are added in combination with two or more types of particles with different average particle sizes, and the film A containing the particles has a d1 Since the film has a structure in which the layer is approximately the same thickness or preferably thinner, there are protrusions on the surface of the film A layer that correspond to the particle size added, that is, two or more heights, and each By forming protrusions with little variation in height, the effect of the present invention is dramatically improved compared to a film containing particles having only one type of average particle size.

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

The film obtained by the present invention is a film in which the above composition is biaxially oriented. A single film or a non-oriented film is not preferable because it has poor scratch resistance. The degree of this orientation is not particularly limited, but the scrub resistance will be even better if the Young's modulus, which is a measure of the degree of molecular orientation of the polymer, is 350 kg/■ or more in both the longitudinal and width directions. Therefore, it is highly desirable. Although the upper limit of Young's modulus, which is a measure of the degree of molecular orientation, is not particularly limited, the manufacturing limit is usually about 1,500 J/wa''.

Furthermore, even if the Young's modulus of the film obtained by the present invention is within the above range, the orientation of the polymer molecules in a part of the thickness direction of the film, for example near the surface layer, is not oriented or uniaxially oriented, that is, the entire thickness direction is not uniaxially oriented. It is particularly preferable that the molecular orientation is biaxial because the scratch resistance and dubbing resistance become even better.

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

Further, the thermoplastic resin A is a crystalline polyester, and the total reflection Raman crystallization index of the surface of the film A obtained in the present invention is 20 c or less, preferably 1.
A thickness of 8 cm-" or less, more preferably 1 cm-" or less, is extremely desirable because scratch resistance and dubbing resistance are even better.

The thickness of the film A obtained by the present invention has scratch resistance,
From the point of view of dubbing resistance, the thickness is 0.01 to 3 μm, preferably 0.01 to 3 μm.
02-1μm1 More preferably 0.03-0.5μm
It is desirable that

The average protrusion height on the surface of film A obtained by the present invention is 5
~500 am, preferably 10-300 am.

More preferably, it is in the range of 15 to 200 .ANG., since scratch resistance and dubbing resistance become even better.

It is particularly desirable that the average distance between the protrusions of the film A obtained in the present invention be 6 μm or less, preferably 4 μm or less, since the scratch resistance and dubbing resistance will be even better.

As mentioned above, in the film obtained by the present invention, it is extremely desirable that the thermoplastic resin constituting the film be crystalline or melt-optically anisotropic; however, in the case of a melt-isotropic film, the crystallization parameter ΔTcπ is 25 to A temperature of 65° C. is particularly desirable because the scratch resistance becomes even better.

In addition, when the thermoplastic resin A is polyester, it is particularly desirable that the refractive index of the film 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, it is particularly desirable when the angle is 0°70 or more because the scratch resistance becomes even better.

As the thermoplastic resin B, a crystalline polymer is desirable, and it is particularly desirable when the crystallinity parameter ΔTcH is in the range of 20 to 100°C, since the dubbing resistance becomes even better. Specific examples include polyester, polyamide, polyphenylene sulfide, and polyolefin.
Among these, polyester is particularly desirable because it provides even better dubbing resistance. Further, as polyesters, ethylene terephthalate, ethylene a, β-bis(2-chlorophenoxy)ethane-4,41-dicarboxylate, ethylene 2. It is preferable to use at least one type of structural unit selected from tonaphthalate units as the main constituent, since 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%. Furthermore, the thermoplastic resins B and A may be of the same type or may be of different types.

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

There is no particular need to add inert particles to Film B, which has thermoplastic resin B as its main component, but if the average particle size is 0.01
~2μm1 especially 0.02-0.5μm inert particles
．． 001-0.15% by weight, especially 0.005-0.05
Adding it in an amount by weight is extremely desirable because it not only improves the scratch resistance but also improves the winding appearance of the film. As for the type of inert particles to be added, it is desirable to use those preferably used for thermoplastic resin A. The types and sizes of particles added to thermoplastic resins A and B may be the same or different.

The difference (A-B) in crystallization parameter ΔTcH 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 the scratch resistance and dubbing resistance become even better.

Next, the method for producing fino mushrooms of the present invention will be explained.

First, as a method for adding inert particles to 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 added to a predetermined dicarboxylic acid component. It is effective to polymerize the film with the thickness and average particle size relationship and addition amount 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 the amount of addition 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 thickness and average particle size relationship and additive amount within the range of the present invention. be.

Another method for adding inert particles to thermoplastic resins is to heat-treat the particles in ethylene glycol and then
A method of mixing the slurry with a thermoplastic resin in which the solvent is replaced with water and kneading it into the thermoplastic resin using a vent type twin-screw extruder also has the relationship between the thickness and average particle size within the range of the present invention. It is extremely effective in obtaining additive amounts of film.

A method for adjusting the amount of particles added 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 amount of particles added. The method is valid. As a method for adding at least two types of inert particles to a thermoplastic resin, at least two types of inert particles are dispersed in advance in the form of a diol component slurry as described above, and this is polymerized with a predetermined dicarboxylic acid component, It is possible to use either a method in which a high concentration master polymer containing each inert particle is prepared as described above and the amount of each inert particle added is adjusted during film formation.

Thus, the pellets containing predetermined amounts of at least two types of inert particles are optionally dried.

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

Thermoplastic resins A and B are supplied to a known extruder for melt lamination, extruded into a sheet through a slit-shaped die, and cooled and solidified 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 bomb in the polymer flow path of thermoplastic resin A is effective for obtaining a film having a relationship between thickness and average particle size and an addition amount within the range of the present invention. In addition, the melting temperature of the extruder on the thermoplastic resin A side should be 10 to 40°C higher than that on the thermoplastic resin B side. It is effective to obtain

Next, this unstretched film is biaxially stretched and biaxially oriented. As a stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used, but a sequential biaxial stretching method in which stretching is first performed in the longitudinal direction and then in the width direction is preferred; Divided into stages or more, the total longitudinal stretching ratio is 3.0
A method in which the thickness is increased by a factor of 6.5 is effective for obtaining a film having a relationship between thickness and average particle size and an additive amount 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. The longitudinal stretching temperature varies depending on the type of thermoplastic resin and cannot be generalized, but it is usually 50 to 130°C in the first stage and higher in the second and subsequent stages to achieve the thickness and average grain size within the range of the present invention. It is effective in obtaining a film having an orientation state within a desired range depending on the diameter relationship and the amount added. The stretching speed in the longitudinal direction is preferably in the range of 5.000 to 50%/sin (1110%/sin).As the stretching method in the width direction, a method using a stencil is generally used, and the stretching ratio is 3.0 to 5.0%/sin. A range of 0 times is appropriate.The stretching speed is 1.eoo to 20.Go.
o%/grim, and the temperature is preferably in the range of 80 to 160°C. Next, this stretched film is heat treated. The heat treatment temperature in this case is 170-200℃, especially 170-190℃
The time is preferably in the range of 0.5 to 60 seconds.

[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 inert particles were measured as an ethylene glycol or water slurry using a centrifugal sedimentation type particle size distribution analyzer and expressed as the average particle size.

0 Particle size ratio It is the ratio of the average value of the major axis to the average value of the minor axis of individual particles.

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

Major axis = ΣDli/N Minor axis = ΣD2i/N DI# and D2j are the major axis (maximum diameter) of each individual particle
, the shortest axis (shortest axis), and N are the total number.

0 Relative standard deviation of particle size Standard deviation calculated from individual particle diameter Di, average diameter D1, total number of particles N σ (=(Σ(Di-D)”/N) 1/2
) divided by the average diameter (σ/D).

4》 Addition amount of particles Select a solvent that dissolves the thermoplastic resin but does not dissolve the particles.
The particles are centrifuged from the thermoplastic resin, and the ratio (weight %) of the particles to the total weight is defined as the amount of particles added. In some cases, infrared spectroscopy may also be effective.

0 Crystallization parameter ΔTcH, 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 300
After melting for 5 minutes at a temperature of °C, it is quenched into liquid nitrogen.

This rapidly cooled sample is heated at 10° C./ii, 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 Tce. The temperature was further increased, and the heat of fusion was determined from the melting peak. Here, the difference between Tcc and Tg (Tcc-TH) was defined as the crystallization parameter ΔTcH.

6) Molecular orientation (refractive index) on the surface, total reflection on the surface, and crystallization index were measured using an Atsube refractometer using sodium D line (589 m) 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.
l, N2, and N3, the absolute value of (Nl - N2) is 0.07 or less, and N3 / ((Nl + N
2) One criterion can be that /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 available at jobin-mama ■
The total reflection Raman spectrum was measured using a 1m+unor U-l (10) Raman system manufactured by the company; for example, in the case of polyethylene terephthalate, it was 1.615 cl-
” (skeletal vibration of benzene ring) and 1,730 c+s
” (Stretching vibration of carbonyl group) Polarization measurement ratio of band intensity ratio (YY/XX ratio, etc.) Here, the polarization direction of the YY laser is set to Y, and the man light detection parallel to Y, xx
It is possible to make use of the fact that the direction of polarization of the Nylaser is set to X and that the direction of polarization parallel to X (man light detection) corresponds to the molecular orientation. The biaxial orientation of a polymer is determined by converting the parameters obtained from Raman measurement into the refractive index in the longitudinal direction and width direction, and its absolute value,
It can be determined based on the difference. Further, the half-width of 1, Tg (I cm''), which is the stretching vibration of the carbonyl group, 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 (5,145A) ■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 6
It was set to 0°.

■Detector PM: 11CA31/34/Pl+otom
CowaliaHSyslc-(Iamimsisw
C1230) (SwllllllF 1611
(IV) ■Measurement conditions 8L17 1000μI LASERl (ihW G17E TIME 1. Osec3CAN
SPEED 12cm-”/sinSAi
lPLING INTERVAL 0.2 cr
a-" REPEAT TIME 6 Average height of surface protrusions Image of the measured height of protrusions when scanning with a two-detector type scanning electron microscope and a cross-section measuring device, with the height of the flat surface of the film set as 0. The film is sent to a processing device and the film surface protrusion image is reconstructed on the image processing device.
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. ◎Go Select a value between -10,000 times.

[F]》 Young's modulus: 2 using an Instron type tensile tester according to the method specified in JIS-Z-1702.
Measurement was performed at 5° C. and 65% RH.

(2) 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] 10 K[η] 2 · C, where ηS, = (solution viscosity/solvent viscosity) -1, C is the weight of dissolved polymer per 100 ml of solvent (g/109 m
l, usually 1.2), is the Huggins constant (taken to be 0,343). In addition, solution viscosity and solvent viscosity were measured using an Ostwald viscometer.

■ A scratch-resistant film slit into a tape with a width of 1/2 inch was run on a guide pin (surface roughness: 100 nm in Ra) using a tape running tester (running speed 1).
, ooom/min, number of runs 10 passes, wrapping angle = 60
°, 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/am, the product was cured at 70°C for 48 hours. The original tape was slit into 172-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 = 5 parts by weight - Lecithin
= 1 part by weight methyl ethyl ketone
Nia 5 parts by weight methyl isobutyl ketone = 7
5 parts by weight, toluene = 75 parts by weight, carbon black = 2 parts by weight, lauric acid: 1.5 parts by weight.
A 00% chroma signal was recorded, and the chroma S/N was measured from the reproduced signal using a color video noise measuring device and designated 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. The chroma S/N drop (A-B) due to this dubbing is 3d
If less than B, dubbing resistance: Excellent, 5d above 3dBJ2L
A value of 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 First, thermoplastic resin A is prepared. An ethylene glycol slurry containing crosslinked polystyrene particles, silica particles derived from colloidal silica, or calcium carbonate particles with different average particle sizes is prepared, and after heat-treating this ethylene glycol slurry at 190°C for 2 hours, dimethyl terephthalate and ester are prepared. Exchange reaction is carried out, polycondensation is carried out, and the particles are
Master pellets of polyethylene terephthalate containing 10% by weight were made. At this time, the polycondensation time was adjusted so that the intrinsic viscosity was 0.65. Next, the intrinsic viscosity is 0.
EXAMPLE 62 Polyethylene terephthalate substantially free of inert particles was prepared and designated as Thermoplastic Resin B. These polymers were each dried at 180°C for 6 hours under reduced pressure (3Te
rr) I did. Thermoplastic resin A containing inert particles having different average particle sizes is mixed and the content of one or two types of particles is adjusted, and the thermoplastic resin A is supplied to the extruder 1.
The thermoplastic resin B is melted at 0°C, further supplied to the extruder 2, melted at 280°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. At this time, an unstretched film was prepared with a ratio of die slit gap/unstretched film thickness of 10. In addition, by adjusting the discharge amount of each extruder, the total thickness, thermoplastic resin A
The layer thickness was adjusted. This unstretched film was heated to 85°C.
The film was stretched 3.6 times in the longitudinal direction. This stretching was carried out in four stages with a difference in peripheral speed between two sets of rolls. This uniaxially stretched film was stretched at a stretching speed L O (10%/
Stretched 4°0 times in the width direction at 105°C for 2 minutes at a constant length.
Heat treatment was performed at 10° C. for 5 seconds to obtain a biaxially oriented laminated film having a total thickness of 15 μm, 1 thermoplastic resin A layer thickness of 0.02 to 3 μm. The parameters of the present invention for these films are as shown in Table 1, and when the parameters of the present invention are within the range, the scratch resistance and dubbing resistance are 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] By devising a manufacturing method, the present invention has created a film with a special surface morphology that was previously unobtainable, so it is able to achieve both extremely high levels of friction coefficient and output characteristics when used for magnetic recording media. Film can be obtained, which 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 (3)

[Claims] (1) A film A whose main component is a thermoplastic resin A containing at least two types of inert particles having different average particle diameters is laminated on at least one side of a film B whose main component is a thermoplastic resin B. In the method for producing a biaxially oriented thermoplastic resin film, when the minimum average particle size of the above inert particles added to the thermoplastic resin A is d_1,
2 to 20% by weight of inert particles having an average particle diameter d_1 are added to the thermoplastic resin A, and the thickness t and d_1 of the film A mainly composed of the thermoplastic resin A after biaxial stretching heat treatment.
A method for producing a biaxially oriented thermoplastic resin film, characterized in that the film is laminated so that the ratio t/d_1 of t/d_1 is 0.1 to 5. (2) For each of the inert particles having different average particle sizes added to thermoplastic resin A, the particle size ratio is 1.0
The method for producing a biaxially oriented thermoplastic resin film according to claim 1, wherein the molecular weight is 1.3. (3) The biaxial orientation heat according to claim (1) or 2, wherein each of the inert particles having different average particle diameters added to the thermoplastic resin A has a relative standard deviation of particle diameter of 0.6 or less. A method for producing a plastic resin film.