JPH03210339A - Biaxially oriented thermoplastic resin film and production thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

[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-59-01818, 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] In order to achieve the above object, the present invention provides a film mainly composed of a thermoplastic resin A containing crosslinked polymer particles having a functional group, wherein the average of the particles is The particle size is 0.2 to 5 times the film thickness, and the content of the particles is 0.5 to 20% by weight.
A biaxially oriented thermoplastic resin film with a thickness of 0.01 to 3 μm characterized by The method for producing the biaxially oriented thermoplastic resin film is characterized in that the crosslinked polymer particles are contained in the thermoplastic resin A by adding water and/or an organic compound slurry having a boiling point of 200° C. or less. It is.

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

In the film of the present invention, it is necessary that the thermoplastic resin A contains crosslinked polymer particles having a functional group.

The crosslinked polymer particles generally include a monovinyl compound (A) having only one aliphatic unsaturated bond in the molecule, and a compound (B) having two or more aliphatic unsaturated bonds in the molecule as a crosslinking agent. ), but the present invention is not limited thereto, and any crosslinked polymer particles that are insoluble and infusible may be used.

Examples of compound (A) include aromatic monovinyl compounds such as styrene, α-methylstyrene, fluorostyrene, and vinylbiline, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, butyl acrylate, and 2-ethylhexyl. Acrylic acid ester monomers such as acrylate, methyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, N,N''-dimethylaminoethyl acrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl Methacrylic acid ester monomers such as methacrylate, N,N''-dimethylaminoethyl methacrylate-1, mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid and acid anhydrides of dicarboxylic acids, acrylamide, methacrylate An amide monomer such as amide can be used. Among them, styrene, α-methylstyrene and p-methylstyrene are preferred.

Examples of compound (B) include divinylbenzene compounds,
Or trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylol Included are polyhydric acrylates and methacrylates such as propane trimethacrylate. Among the above, it is particularly preferable to use divinylbenzene, ethylene glycol dimethacrylate, or trimethylolpropane trimethacrylate.

Two or more of these compounds (A) and (B) can also be used in combination.

Preferred examples of the composition of the crosslinked polymer particles of the present invention include styrene-divinylbenzene copolymer, styrene-acrylonitrile-divinylbenzene copolymer,
Examples include styrene-methyl methacrylate-divinylbenzene copolymer. Among them, styrene-divinylbenzene copolymer is particularly preferred in terms of heat resistance.

In the present invention, it is necessary that the crosslinked polymer particles have a functional group. That is, a functional group that improves affinity with thermoplastic resins is required. The type of such functional group is not particularly limited, but examples include carboxyl group, hydroxyl group, sulfone group, and ester group. Among these, metal salts thereof are preferred because they improve affinity with thermoplastic resins, and metal salts of carboxyl groups are particularly preferred. Furthermore, from the point of view of the heat resistance of the particles, it is preferable to produce particles that serve as a base for -degree hypercrosslinking, and to introduce functional groups onto the surface of the base particles. For example, when introducing a metal salt of a carboxyl group, a styrene-divinylbenzene copolymer is used as the base particle to produce particles that are highly crosslinked with divinylbenzene, and then a carboxyl group is introduced onto the particle surface using methacrylic acid. . By setting the inside of the particle production system to the alkaline side, the -COONa functional group is introduced onto the particle surface. The amount of monomer for introducing these functional groups is preferably 0.01 to 20% by weight, more preferably 0.1 to 10% by weight based on the base particle.

In addition, the crosslinked polymer particle slurry contains anionic surfactants such as sodium dodecylbenzenesulfonate and sodium lauryl sulfate, and nonionic surfactants such as polyoxyethylene nonylphenyl ether and polyethylene glycol monostearate, which are necessary for the particle manufacturing method. It is preferable to include a protective agent such as a surfactant, polyvinyl alcohol, or carboxymethyl cellulose from the viewpoint of particle dispersibility.

Furthermore, regarding the heat resistance of the crosslinked polymer particles of the present invention, particles having a thermal decomposition temperature (10% weight loss temperature) measured by a thermobalance of 380°C or higher are preferable, and more preferably 4°C or higher.
The temperature is 00°C or higher, particularly preferably 410°C or higher. 38
If it is below 0°C, particles will aggregate during polymer production, melt molding, or recovery and reuse of molded products, resulting in poor scratch resistance and dubbing resistance, which is not preferable. In order to have such heat resistance, it is necessary to highly crosslink the compound (B) with a crosslinking agent. The type of crosslinking agent is not particularly limited, but divinylbenzene is preferred, and it is required to be 12% by weight or more of pure divinylbenzene based on the monomer, preferably 35% by weight or more, and more preferably 55% by weight.
That's all.

The crosslinked polymer particles contained in the thermoplastic resin A of the present invention have a particle size ratio (longer diameter/breadth diameter of the particles) of 1.0 to 1.
．． The particles of No. 3, especially spherical particles, are preferable because they provide even better scratch resistance.

Further, the crosslinked polymer particles in the thermoplastic resin A of the present invention have a relative standard deviation of 0. 5 or less, preferably 0.degree. or less, since scratch resistance and dubbing resistance become even better.

The size of the crosslinked polymer particles is such that the average particle size in the film is 0.2 to 5 times the thickness of the film made of thermoplastic resin A.
times, preferably 0. 5 to 5 times, more preferably 1.
It is necessary to be in the range of 1 to 3 times. If the average particle diameter/film thickness ratio is smaller than the above range, the scratch resistance will be poor, and if it is too large, the scratch resistance and dubbing resistance will be poor, which is not preferable.

In addition, the average particle diameter of the crosslinked polymer particles in thermoplastic resin A (
diameter) of 0.01 to 1 μm, especially 0.02 to 0.5 μm
It is preferable that the viscosity is in this range because scratch resistance and dubbing resistance become even better.

The content of the crosslinked polymer particles in the thermoplastic resin A of the present invention needs to be 0.5 to 20% by weight, preferably 1 to 10% by weight, and more preferably 1.5 to 8% by weight. be. 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 main component of the film of the present invention is a composition consisting of the thermoplastic resin A and crosslinked polymer particles, but other types of polymers may be blended within a 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.

The film of the present invention is a film in which the above composition is 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 measure of the degree of molecular orientation of the polymer, is 3501<g/
A thickness of mm2 or more is highly desirable because the scratch resistance becomes even better. The upper limit of Young's modulus, which is a measure of the degree of molecular orientation, is not particularly limited, but is usually 1
The manufacturing limit is about 500 kg/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, the thermoplastic resin A is a crystalline polyester, and the total reflection Raman crystallization index of the surface thereof is 20 cm -' or less, preferably 18 cm -' or less, more preferably 17
cm-' or less is extremely desirable because scratch resistance and dubbing resistance become even better.

The thickness of the film made of thermoplastic resin A of the present invention is 0.
It is necessary that the thickness is 0.01 to 3 μm, preferably 0.02 to 1 μm, and more preferably 0.03 to 0.5 μm. If the film thickness is smaller than the above range, the dubbing resistance will be poor, and if it is larger than the above range, the scratch resistance will be poor, which is not preferable.

The average protrusion height of the surface protrusions formed on the surface of the film made of thermoplastic resin A of the present invention is 5 to 500 nm, preferably 10 to 300 nm, more preferably 15 to 20 nm.
A range of 0 nm is particularly desirable because scratch resistance and dubbing resistance become even better.

It is particularly desirable that the average protrusion spacing of the film made of the thermoplastic resin A of the present invention be 6 μm or less, preferably 4 μm or less, since this provides even better scratch resistance and dubbing resistance.

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

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

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

As the thermoplastic resin B, a crystalline polymer is desirable, and it is particularly desirable when the crystallinity parameter ΔTcg 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.
Polyester is particularly desirable because it provides even better dubbing resistance. In addition, the polyester mainly contains at least one structural unit selected from ethylene terephthalate, ethylene α, β-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate, and ethylene 2,6-naphthalate units. When used as a constituent component, it is desirable 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 of thermoplastic resin B, but the average particle size is 0.01 to 211 m%.
Especially 0. 02~0. 5 μm particles are 0°001~0
．． A content of 5% by weight, particularly 0.005 to 0.3% by weight, is extremely desirable since scratch resistance becomes even better. The types of particles contained are not limited, but
It is desirable to use a thermoplastic resin that is preferably used for thermoplastic resin A. The types and sizes of particles contained in thermoplastic resins A and B may be the same or different.

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

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

First, as the crosslinked polymer particles having a functional group of the present invention, those obtained by a known production method can be used.

Known manufacturing methods include the following methods, for example, by emulsion polymerization.

■ Soap-free polymerization, that is, polymerization without the use of emulsifiers or with very small amounts of emulsifiers.

■ A seed polymerization method in which polymer particles are added to the polymerization system prior to emulsion polymerization and emulsion polymerization is carried out.

■ A core-shell polymerization method in which a portion of the monomer components is emulsion polymerized, and the remaining monomers are polymerized within the polymerization system.

■ JP-A-54-97582 and JP-A-54
Polymerization method by Nigelstad et al. shown in JP-A-126288.

■ A polymerization method that does not use a swelling aid in the method of (■).

Among the above methods, methods (1) and (2) are particularly preferred because they can yield spherical crosslinked polymer particles having a uniform particle size distribution.

After introducing a functional group to the surface of the crosslinked polymer particles, the thermoplastic resin A can be made to contain the crosslinked polymer particles using a vent molding machine. A method of adding an organic compound slurry having a boiling point of 200° C. or lower is extremely effective for obtaining a film having a relationship between thickness and average particle size and content within the range of the present invention.

As a method for adjusting the content of the crosslinked polymer particles,
An effective method 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 content of crosslinked polymer particles.

After drying the pellet containing a predetermined amount of the crosslinked polymer particles as required, the pellet is fed to a known melt extruder and extruded into a sheet through a slit die at temperatures above the melting point and below the decomposition point of the thermoplastic resin. It is extruded and cooled and solidified on a casting roll to produce an unstretched film.

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, a longitudinal stretching ratio of 1.0 to 1.1 times is appropriate.

Although the longitudinal stretching temperature varies depending on the type of thermoplastic resin and cannot be generalized, it is usually 50 to 130 ℃ in the first stage.
It is effective to set the temperature at a temperature of 0.degree. The stretching speed in the longitudinal direction is 5,000 to 50. [A range of 100%/min is preferred.

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 1000 to 20,000
%/min, and the temperature is preferably in the range of 80 to 160°C. Next, this stretched film is heat treated. In this case, the heat treatment temperature is preferably 170 to 200°C, particularly 170 to 190°C, and the time is preferably in the range of 0.5 to 60 seconds.

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

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

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

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

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

Major axis = ΣDli/N Minor axis = ΣD2i/N D l i s D 2 + is the major axis (maximum diameter) and minor axis (shortest axis) of each individual particle, and N is the total number.

(3) Relative standard deviation of particle size Average diameter D1 of each particle measured by the method in (1) above
Standard deviation σ (=(Σ(Di
−D) 2/N) ”' ) divided by the average diameter (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) Thermal decomposition temperature of particles A thermobalance loss curve was measured at a heating rate of 20° (::/min) in a nitrogen atmosphere. The 10% weight loss temperature was taken as the pyrolysis temperature.

(6) Crystallization parameter ΔTcg, heat of fusion measured using a differential scanning calorimeter. The measurement conditions are as follows. That is, 10+ng of the sample was set in a differential scanning calorimeter, and 3
After melting at a temperature of 00°C for 5 minutes, it is quenched into liquid nitrogen. This rapidly cooled sample is heated at a rate of 10° 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.

(7) Molecular orientation (refractive index) on the surface, total reflection Raman crystallization index on the surface Measured using an Atsube refractometer using sodium D line (589 nm) as a light source. Methylene iodide was used as the mounting solution, and the measurement was performed at 25° C. and 65% RH. The biaxial orientation of the polymer has a refractive index of N in the longitudinal direction, width direction, and thickness direction.
1, N2, and N3, 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 by Jobin-Yvon
The total reflection Raman spectrum was measured using a Ramanor U-1000 Raman system manufactured by
In the case of , the polarization measurement ratio (Y Y/X It is possible to utilize the fact that XX corresponds to the molecular orientation. The biaxial orientation of a polymer can be determined by converting the parameters obtained from Raman measurement into refractive indices in the longitudinal direction and width direction, and based on their absolute values, differences, etc. Further, the half-value width of 1730 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 (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: RC^31034/Photon County
ng System ([lamamatsu Cl23
0) (supply 16 [10V) ■Measurement conditions 5LIT 1000. cunLASER
100rnW GATE TIME 1.0secSCAN
5PEED 12cF'/minSAMPLI
NG INTERVAL O,2crnREPEAT
TIME 6 (8) Average height of surface protrusions Image processing of the measured value of the height of protrusions when scanning with the height of the flat surface of the film surface as 0 using a two-detector type scanning electron microscope and a cross-sectional measuring device and reconstruct the film surface protrusion image 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 the scanning electron microscope is selected to be between 1.00Q and 10.000 times.

(9) Young's modulus 25
Measured at 0165% RH.

(10) Intrinsic viscosity [η (unit: d1/g) A value calculated from the following formula from the solution viscosity measured at 25°C in orthochlorophenol is used.

That is, ηsP/c = [η] 10K[η]2 ・With a smile, η5
．． =(solution viscosity/solvent viscosity)-1, C is solvent 100ml
Dissolved polymer weight per unit (g/l 00 m, 1,
Usually 1.2), K is Huggins constant (set to 0,343)
. In addition, solution viscosity and solvent viscosity were measured using an Ostwald viscometer.

(11) A scratch-resistant film slit into a 1/2 inch wide tape was run over a guide bin (surface roughness: Ra, 10,100 nm (running speed 1) using a tape running tester.
．． 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.

(12) A magnetic paint having the following composition is applied to the 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 near 0°01 linear pressure + 200 kg/am, the product was cured at 70° C. for 48 hours. The original tape was slit into 1/2 inch pieces to make pancakes. 250m long from this pancake
This length was incorporated 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
: 75 parts by weight ・Methyl isobutyl ketone :
75 parts by weight・Toluene: 75 parts by weight・Carbon black 2 parts by weight・
Lauric acid: 1.5 parts by weight A 100% chroma signal was recorded on this tape using a TV test waveform generator using a home VTR, and the chroma S/N was measured from the playback signal using a color video noise measuring device. did.

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 reduction in chroma S/N (A-B) due to this dubbing is 3
Dubbing resistance if less than dB: Excellent, 3dB or more 5dB
If it was less than 5 dB, it was judged as good, and if it was 5 dB or more, it was judged as bad. 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 After transesterifying ethylene glycol with dimethyl terephthalate, the thermoplastic resin A) was polycondensed, and functional groups were added to various surfaces of the thermoplastic resin A in a vent molding machine. Pellets of polyethylene terephthalate (hereinafter abbreviated as PET) containing 0.5 to 5% by weight of crosslinked polymer particles having functional groups with different average particle diameters by adding water and an organic compound slurry of crosslinked polymer particles having made.

The intrinsic viscosity of this polymer was 0.63. In addition, PET having an intrinsic viscosity of 0.64 and containing substantially no particles was produced by a conventional method, and was designated as thermoplastic resin B. These polymers were each dried at 180°C for 6 hours under reduced pressure (3 Torr).
) did. Thermoplastic resin A is supplied to extruder 1 and heated to 285°C.
and further supply thermoplastic resin B to extruder 2,
These polymers are melted at 280°C, combined and laminated in a combined block (feed block), then wound around a casting drum with a surface temperature of 25°C using the electrostatic casting method, and cooled and solidified to form a two-layer structure. I made a stretched film. At this time, an unstretched film was prepared with a ratio of die slit gap/unstretched film thickness of 10. In addition, 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.degree. 5 times in the longitudinal direction at a temperature of 82.degree. This stretching was carried out in four stages with a difference in peripheral speed between two sets of rolls. This -axially stretched film was stretched using a stenter at a stretching speed of 2.000%/min.
Stretched 4.0 times in the width direction at 00℃ and stretched at 210℃ under constant length.
Heat treated for 5 seconds at
A biaxially oriented laminated film with a layer thickness of 0.1 to 6 μm was obtained.

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

[Effect of the invention] The present invention uses a thermoplastic resin containing crosslinked polymer particles having functional groups by devising a manufacturing method to specify the relationship between particle size and film thickness, content, and film thickness. Since the above film or a laminated film thereof was used, it was possible to obtain a film with excellent scratch resistance, and a film with excellent dubbing resistance when used for magnetic recording media, making it suitable for various uses. This makes it possible to cope with an increase in film processing speed. 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 not coated with a magnetic layer, and for other uses, it is the surface that is not coated with a magnetic layer, and for other uses, it is the surface that is not coated with a magnetic layer). It is preferable to use it as an unfinished surface.

Furthermore, the film having the laminated structure of 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 the laminated film made by coating during or after the film forming process.
Since the molecules in the outermost layer are also biaxially oriented, in addition to the above-mentioned properties, for example, surface abrasion resistance is far superior, and furthermore, it is advantageous in terms of cost and quality stability.

Claims (4)

[Claims] (1) A film mainly composed of thermoplastic resin A containing crosslinked polymer particles having a functional group, the particles having an average particle diameter of 0.2 to 5 times the thickness of the film, and containing the particles. Thickness 0.5% to 20% by weight.
01-3 μm biaxially oriented thermoplastic resin film. (2) A biaxially oriented thermoplastic resin film obtained by laminating the thermoplastic resin film according to claim (1) on at least one side of a film whose main component is thermoplastic resin B that does not substantially contain particles. (3) 0.001 particles with an average particle size of 0.01 to 2 μm
A biaxially oriented thermoplastic resin film obtained by laminating the thermoplastic resin film according to claim 1 on at least one side of a film whose main component is thermoplastic resin B containing ~0.5% by weight. (4) In the method of incorporating crosslinked polymer particles having a functional group into thermoplastic resin A, a vent molding machine is used to add water and/or an organic Claims (1) to (1) characterized in that the compound is contained by adding a compound slurry.
The method for producing a biaxially oriented thermoplastic resin film according to any one of 3).