JP2682178B2 - Biaxially oriented thermoplastic resin film and method for producing the same - Google Patents

Description

TECHNICAL FIELD 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 having improved running properties on at least one side is known (for example, JP-A-59-111818).

[Problems to be Solved by the Invention] However, in the above-mentioned conventional biaxially oriented thermoplastic resin film, for example, a magnetic layer coating in a magnetic medium application,
Along with an increase in the process speed such as a calendering process or a process for producing a soft tape or the like by dubbing the resulting video tape or the like, there has been a defect that the film surface is damaged by a contacting roll or guide. Further, the conventional one has a drawback that the image quality on a video tape, that is, the S / N (signal / noise ratio) is insufficient due to the deterioration of the image quality during dubbing.

The present invention solves this problem, and particularly, the biaxially oriented heat hardly damages the film in a high-speed process (hereinafter, referred to as excellent in scratch resistance), and has little deterioration in image quality during dubbing (hereinafter, referred to as excellent in dubbing resistance). An object is to provide a plastic resin film.

[Means for Solving the Problems] In order to achieve the above object, the present invention has a thermal decomposition temperature having a metal salt of a functional group on at least one surface of a film (B layer) containing a thermoplastic resin B as a main component. A film containing a thermoplastic resin A containing a thermoplastic resin particle having a cross-linked polymer particle having a (10% weight loss temperature) of 380 ° C. or more as a main component, wherein the average particle diameter of the particle is the film thickness. 0.2
To 5 times, the content of the particles is 0.5 to 20% by weight, and the biaxially oriented thermoplastic resin is formed by laminating a biaxially oriented thermoplastic resin film (A layer) having a thickness of 0.01 to 3 μm. A film and a method of incorporating thermoplastic resin A with crosslinked polymer particles having a metal salt of a functional group, wherein the thermoplastic resin A is mixed with water and / or a boiling point of 200% by using a venting molding machine. The method for producing the biaxially oriented thermoplastic resin film is characterized in that the organic compound slurry is added by adding an organic compound slurry at a temperature of not higher than 0 ° C.

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 α, β-bis (2-chlorophenoxy) ethane-4, When at least one structural unit selected from 4'-dicarboxylate and ethylene 2,6-naphthalate units is the main constituent, scratch resistance and dubbing resistance are further improved, which is desirable. Further, the thermoplastic resin A constituting the present invention
Is extremely desirable because it has more excellent scratch resistance and dubbing resistance in the case of crystallinity or optical anisotropy during melting. The term "crystallinity" as used herein means that it is not amorphous, and quantitatively, the cold crystallization temperature Tcc in the crystallization parameters is detected, and the crystallization parameter ΔTcg is 150 ° C. or less. Further, when the heat of fusion (change in enthalpy of fusion) measured by a differential scanning calorimeter shows a crystallinity of 7.5 cal / g or more, scratch resistance and dubbing resistance are further improved, which is extremely desirable. Further, in the case of a polyester containing ethylene terephthalate as a main component, it is particularly desirable because the dubbing resistance and the scratch resistance are further improved. Note that two or more kinds of thermoplastic resins may be mixed or a copolymer may be used as long as the present invention is not impaired.

The layer A of the film of the present invention is required to contain the crosslinked polymer particles having the functional group metal salt in the thermoplastic resin A.

As the crosslinked polymer particles, generally, a monovinyl compound (A) having only one aliphatic unsaturated bond in the molecule,
Examples of the cross-linking agent include a copolymer with a compound (B) having two or more aliphatic unsaturated bonds in the molecule, but the cross-linking agent is not limited thereto, and insoluble and infusible cross-linked polymer particles are included. Anything will do as long as it is.

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

Examples of the compound (B) include divinylbenzene compound, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol diacrylate, 1,3- Mention may be made of polyvalent acrylates and methacrylates such as butylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate.
Among them, it is particularly preferable to use divinylbenzene, ethylene glycol dimethacrylate or trimethylolpropane trimethacrylate.

These compounds (A) and (B) may be used as a mixture of two or more kinds.

Preferred examples of the composition of the crosslinked polymer particles of the present invention include a styrene-divinylbenzene copolymer, a styrene-acrylonitrile-divinylbenzene copolymer, a styrene-methylmethacrylate-divinylbenzene copolymer and the like. Among them, a styrene-divinylbenzene copolymer is particularly preferable in terms of heat resistance.

In the present invention, it is necessary that the crosslinked polymer particles have a functional group metal salt. That is, a functional group that improves the affinity with the thermoplastic resin is required, and the type of the functional group is not particularly limited, but examples thereof include a carboxyl group, a hydroxyl group, a sulfone group, and an ester group.
It is necessary to use those metal salts in order to further improve the affinity with the thermoplastic resin, and metal salts having a carboxyl group are particularly preferable. Further, from the viewpoint of the heat resistance of the particles, it is preferable to once manufacture particles that become a highly crosslinked matrix and introduce a metal salt of a functional group on the surface of the matrix particles.
For example, when introducing a metal salt of a carboxyl group, a styrene-divinylbenzene copolymer is used as a base particle to produce a highly crosslinked particle with divinylbenzene, and then a carboxyl group is introduced onto the particle surface with methacrylic acid. . Then, by setting the inside of the particle production system to the alkali side, a functional group of -COONa is introduced to the particle surface. The amount of the 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 mother particles.

Further, in the slurry of crosslinked polymer particles, anionic surfactants such as sodium dodecylbenzene sulfonate and sodium lauryl sulfate, which are necessary for the particle production method, polyoxyethylene nil phenyl ether, nonionics such as polyethylene glycol monostearate, etc. From the viewpoint of particle dispersibility, it is preferable to include a surface active agent, a protective agent such as polyvinyl alcohol and carboxymethyl cellulose.

Furthermore, regarding the heat resistance of the crosslinked polymer particles of the present invention, the thermal decomposition temperature by a thermobalance (10% weight loss temperature) needs to have a heat resistance of 380 ° C. or higher, preferably 400 ° C. or higher, and more preferably It is more than 410 ℃. If the temperature is lower than 380 ° C, particles are aggregated at the time of polymer production, melt molding, or at the time of collecting and reusing a molded product, and scratch resistance and dubbing resistance are deteriorated, which is not preferable. In order to have such heat resistance, it is necessary to highly crosslink with a crosslinking agent of the compound (B). The type of the cross-linking agent is not particularly limited, but among them, divinylbenzene is preferable, and 12% by weight or more is necessary as pure divinylbenzene with respect to the monomer, preferably 35% by weight or more, and more preferably 55% by weight or more.

The particles of the crosslinked polymer contained in the thermoplastic resin A of the present invention have a particle size ratio (major axis / minor axis of particles) of 1.0 to 1.3.
In the case of the above-mentioned particles, particularly spherical particles, scratch resistance is further improved, which is desirable.

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 0.4 or less, because scratch resistance and dubbing resistance are further improved, which is desirable.

The size of the crosslinked polymer particles depends on the thickness of the film (A layer) whose average particle size in the film is made of the thermoplastic resin A.
0.2-5 times, preferably 0.5-5 times, more preferably 1.
It must be in the range of 1 to 3 times. If the average particle diameter / A layer thickness ratio is smaller than the above range, the scratch resistance becomes poor, and conversely if it is large, the scratch resistance and dubbing resistance become poor, which is not preferable.

Further, when the average particle diameter (diameter) of the crosslinked polymer particles in the thermoplastic resin A is in the range of 0.01 to 1 μm, particularly 0.02 to 0.5 μm, scratch resistance and dubbing resistance are further improved. desirable.

It is necessary that the content of the crosslinked polymer particles in the thermoplastic resin A of the present invention is 0.5 to 20% by weight, preferably 1 to 10% by weight, more preferably 1.5 to 8% by weight. If the content of the particles is less than the above range, or if the content is too large, the scratch resistance becomes poor, which is not preferable.

The layer A of the film of the present invention has a composition comprising the thermoplastic resin A and crosslinked polymer particles as a main component, but may be blended with another type of polymer within a range not impairing the object of the present invention, Further, organic additives such as antioxidants, heat stabilizers, lubricants, and ultraviolet absorbers may be added to the extent that they are usually added.

When the film of the present invention is used in the form of a laminated film in which the film (A layer) made of the thermoplastic resin A is laminated on at least one surface of the film made of the thermoplastic resin B, not only the mechanical properties are improved Also, scratch resistance and dubbing resistance are improved. Here, the thermoplastic resins A and B may be the same or different.

As the thermoplastic resin B, a crystalline polymer is preferable, and particularly when the crystallinity parameter ΔTcg is in the range of 20 to 100 ° C., the dubbing resistance is further improved, which is desirable.
Specific examples thereof include polyester, polyamide, polyphenylene sulfide, and polyolefin. In the case of polyester, dubbing resistance is further improved, which is particularly desirable. As the polyester, 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 is mainly used. When it is used as a component, the dubbing resistance is particularly improved, which is desirable. However, other components may be copolymerized within a range that does not impair the present invention and within a range that does not impair desired crystallinity, preferably within 5 mol%.

The thermoplastic resin B of the present invention may be blended with other kinds of polymers as long as the object of the present invention is not impaired, and organic additives such as antioxidants, heat stabilizers, lubricants, and ultraviolet absorbers may be added. The agent may be added to the extent that the agent is usually added.

It is not particularly necessary that the thermoplastic resin B film contains particles, but the average particle size is 0.01 to 2 μm, especially 0.02
~ 0.5μm particles 0.001-0.5% by weight, especially 0.005-0.3
If it is contained in a weight percentage, the scratch resistance is further improved, which is extremely desirable. The type of particles contained is not limited, but it is desirable to use those which are preferably used for the thermoplastic resin A. The types and sizes of the particles contained in the thermoplastic resins A and B may be the same or different.

The difference (AB) between the crystallization parameters ΔTcg of the thermoplastic resin A and the thermoplastic resin B is not particularly limited.
When the temperature is from + 20 ° C., scratch resistance and dubbing resistance are further improved, which is particularly desirable.

The film of the present invention is a film in which the above composition is biaxially oriented. A uniaxial or non-oriented film is not preferred because scratch resistance becomes poor. The degree of this orientation is not particularly limited, but when the Young's modulus, which is a measure of the degree of molecular orientation of the polymer, is 350 kg / mm ² or more in both the longitudinal direction and the width direction, scratch resistance is further improved, so desirable. The upper limit of the Young's modulus, which is a measure of the degree of molecular orientation, is not particularly limited, but usually about 1500 kg / mm ² is the manufacturing limit.

Further, the film of the present invention, even if the Young's modulus is within the above range, a part in the thickness direction of the film, for example, the orientation of polymer molecules in the vicinity of the surface layer is not oriented, or is not uniaxial orientation, that is, When the molecular orientation of the entire portion in the thickness direction is biaxial orientation, scratch resistance and dubbing resistance are further improved, which is particularly desirable.

Especially when the molecular orientation measured by Abbe refractometer, refractometer using laser, total reflection laser Raman method etc. is biaxial orientation on both the front and back surfaces, scratch resistance and dubbing resistance are even better. This is particularly desirable.

Further, the thermoplastic resin A is a crystalline polyester,
When the total reflection Raman crystallization index on the surface is 20 cm ^-1 or less, preferably 18 cm ^-1 or less, more preferably 17 cm ^-1 or less, scratch resistance and dubbing resistance are further improved, which is extremely desirable.

The thickness of the film (A layer) made of the thermoplastic resin A of the present invention is 0.01 to 3 μm, preferably 0.02 to 1 μm, and more preferably 0.03 to 0.5 μm. A
If the layer thickness is smaller than the above range, the dubbing resistance becomes poor, and conversely if it is large, the scratch resistance becomes poor, which is not preferable.

When the average protrusion height of the surface protrusions formed on the surface of the layer A of the present invention is in the range of 5 to 500 nm, preferably 10 to 300 nm, and more preferably 15 to 200 nm, scratch resistance and dubbing resistance are better. It is particularly desirable because it becomes even better.

When the average protrusion spacing of the layer A of the present invention is 6 μm or less, preferably 4 μm or less, scratch resistance and dubbing resistance are further improved, which is particularly desirable.

As described above, in the film of the present invention, it is highly desirable that the thermoplastic resin A constituting the layer A be crystalline or have melt optical anisotropy.
When the crystallization parameter ΔTcg is 25 to 65 ° C., scratch resistance is further improved, which is particularly desirable.

When the thermoplastic resin A is a polyester, when the refractive index in the thickness direction of the surface of the thermoplastic resin A is 1.5 or less, scratch resistance and dubbing resistance are further improved, which is particularly preferable. Furthermore, the intrinsic viscosity of the film is 0.60 or more, especially
When it is 0.70 or more, scratch resistance is further improved, which is particularly desirable.

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

First, as the crosslinked polymer particles having a functional group metal salt of the present invention, those obtained by a known production method can be used. As a known production method, for example, there is a method by emulsion polymerization as described below.

A soap-free polymerization method, that is, a method in which no emulsifier is used or polymerization is performed using an extremely small amount of an emulsifier.

A seed polymerization method in which polymer particles are added to the polymerization system prior to emulsion polymerization and then emulsion polymerization is performed.

A core-shell polymerization method in which a part of the monomer component is emulsion-polymerized and the remaining monomer is polymerized in the polymerization system.

A polymerization method using Eugelstat and the like disclosed in JP-A-54-97582 and JP-A-54-126288.

 The polymerization method without using a swelling aid in the method of the above.

Of the above methods, the methods (1) and (2) are preferable because spherical crosslinked polymer particles having a uniform particle size distribution can be obtained.

As a method of incorporating the crosslinked polymer particles into the thermoplastic resin A after introducing the functional group metal salt onto the surface of the crosslinked polymer particles, a crosslinked polymer particle is added to the thermoplastic resin A in a vent-type molding machine. The method of adding water and / or an organic compound slurry having a boiling point of 200 ° C. or less is extremely effective for obtaining a film having the relationship between the thickness and the average particle diameter and the content within the range of the present invention.

As a method for adjusting the content of the crosslinked polymer particles, a high-concentration master is prepared by the above method, and the crosslinked polymer particles are diluted by a thermoplastic resin that does not substantially contain the particles during film formation. A method of adjusting the content is effective.

Next, as a method for laminating the film made of the thermoplastic resin A containing a predetermined amount of the crosslinked polymer particles on at least one surface of the film made of the thermoplastic resin B, the following method is effective.

A predetermined thermoplastic resin A composition and a thermoplastic resin B (A,
(B may be the same or different) may be supplied to a known extruder for melt lamination, extruded into a sheet form from a slit die, and cooled and solidified on a casting roll to produce an unstretched film. That is, two or three extruders,
Using two or three layers of manifolds or merging blocks, the thermoplastic resins A and B are laminated, and 2 or 3
The sheet of layers is extruded and cooled on a casting roll to make an unstretched film. In this case, a method of installing a static mixer and a gear pump in the polymer flow path of the thermoplastic resin A is effective for obtaining a film having the relationship between the thickness and the average particle size and the content in the range of the present invention. Further, the melting temperature of the extruder on the side of the thermoplastic resin A is 10 to 10 from that on the side of the thermoplastic resin B.
It is effective to raise the temperature by 40 ° C. to obtain a film in the range of the present invention, the relationship between the thickness and the average particle size, the content, and the oriented state in the desired range.

Next, this laminated unstretched film is biaxially stretched to be biaxially oriented. As a stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. However, the sequential biaxial stretching method of first stretching in the longitudinal direction and then in the width direction is used, and the stretching in the longitudinal direction is divided into three stages or more, and the total longitudinal stretching ratio is 3.0 to 6.5 times. It is effective to obtain a film having a content and a content within the range of the invention and an average particle size. However, when the thermoplastic resin is a molten optically anisotropic resin, the stretching ratio in the longitudinal direction is suitably 1.0 to 1.1 times.
The stretching temperature in the longitudinal direction varies depending on the type of the thermoplastic resin and cannot be said unconditionally. However, usually, the first stage is set to 50 to 130 ° C., and the second and subsequent stages are set to be higher than the thickness and average within the range of the present invention. It is effective to obtain a film having a relation of particle size, content and oriented state in a desirable range. The longitudinal stretching speed is preferably in the range of 5,000 to 50,000% / min. As a stretching method in the width direction, a method using a stenter is generally used. The stretching ratio is suitably in the range of 3.0 to 5.0 times. Stretching speed in the width direction is 1,000-20,000% / min, temperature is 80-160
The range of ° C. is preferred. Next, this stretched film is heat-treated. The heat treatment temperature in this case is 170 to 200 ° C, especially 170 to 1
90 [deg.] C. and the time is preferably 0.5 to 60 seconds.

In the case of a laminated film, it is necessary to set the stretching temperature based on the thermoplastic resin A. Further, in the heat treatment step of the two-layer laminated film, it is desirable that the temperature of the hot air blown to the thermoplastic resin A layer is lower than that of the thermoplastic resin B by 3 to 20 ° C., the relationship between the thickness and the average particle size, the content, and the range of the present invention. It is effective for obtaining a film having an oriented state in a range.

[Method for Measuring Physical Properties and Method for Evaluating Effect] The method for measuring characteristic values and the method for evaluating effect according to the present invention are as follows.

(1) Average particle size of particles The thermoplastic resin is removed from the film by a plasma low-temperature incineration method to expose the particles. Processing conditions are selected such that the thermoplastic resin is ashed but the particles are not damaged. This was observed with a scanning electron microscope for 5,000 or more particles, the particle image was processed by an image processor, and the number average diameter D determined by the following equation was defined as the average particle diameter.

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

(2) Particle size ratio It is a ratio of the average value of the major axis / the average value of the minor axis in the measurement of the above (1).

 That is, it is obtained by the following equation.

Major axis = ΣD1i / N Minor axis = ΣD2i / N D1i and D2i are the major axis (maximum diameter), minor axis (shortest axis) and N are the total number of the individual particles, respectively.

(3) Relative standard deviation of particle size Standard deviation σ (= {Σ (Di-
D) ² / N} ^1/2 ) was divided by the average diameter D (σ / D).

(4) Content of Particles A solvent in which the thermoplastic resin is dissolved but the particles are not dissolved is selected, the particles are centrifuged from the thermoplastic resin, and the particle content is defined as a ratio (% by weight) to the total weight of the particles.
In some cases, the combined use of infrared spectroscopy is also effective.

(5) Thermal decomposition temperature of particles Under a nitrogen atmosphere, a thermobalance weight loss curve was measured at a temperature rising rate of 20 ° C / min. The 10% weight loss temperature was taken as the pyrolysis temperature.

(6) Crystallization parameter ΔTcg, heat of fusion It was measured using a differential scanning calorimeter. The measurement conditions are as follows. That is, 10 mg of a sample is set in a differential scanning calorimeter, melted at a temperature of 300 ° C. for 5 minutes, and then rapidly cooled in liquid nitrogen. The quenched 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 crystallization exothermic peak temperature from the glassy 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 of surface (refractive index), total reflection Raman crystallization index of surface Using sodium D line (589 nm) as a light source, measurement was performed using an Abbe refractometer. The measurement was performed at 25 ° C. and 65% RH using methylene iodide as the mounting solution. The biaxial orientation of the polymer is determined by the refractive indices N1, N2, N3 in the longitudinal, width, and thickness directions.
, The absolute value of (N1-N2) is 0.07 or less, and N3 /
One criterion may be that [(N1 + N2) / 2] is 0.95 or less. Further, the refractive index may be measured using a laser refractometer. Further, when measurement is difficult by this method, a total reflection laser Raman method can be used. Ramanor manufactured by Jobin-Yvon is used to measure Raman laser total reflection.
The total reflection Raman spectrum was measured by the U-1000 Raman system. For example, in the case of PET, 1615 cm ^-1 (skeleton vibration of benzene ring) and 1730 cm ^-1 (stretching vibration of carbonyl group)
Polarization measurement ratio of the band intensity ratio of YY / XX ratio etc. where YY:
Raman light detection parallel to Y with the laser polarization direction Y, and XX: Raman light detection parallel to X with laser polarization direction X) correspond to the molecular orientation. The biaxial orientation of the polymer can be determined by converting the parameters obtained from the Raman measurement into the refractive index in the longitudinal direction and the width direction, and from the absolute value, difference, and the like. The total reflection Raman crystallization index of the surface was defined as the half-value width of 1730 cm ⁻¹ , which is the stretching vibration of the carbonyl group. The measurement conditions in this case are as follows.

Light source Argon ion laser (5145Å) Sample setting The film surface is pressed against a total reflection prism, and the angle of incidence of the laser on the prism (the angle with the film thickness direction) is 60
°.

Detector PM: RCA31034 / Photon Counting System (Hamamatsu C1230) (supply 1600V) Measuring condition SLIT 1000μm LASER 100mW GATE TIME 1.0sec SCAN SPEED 12cm ^-1 / min SAMPLING INTERVAL 0.2cm ^-1 REPEAT TIME 6 (8) Average of surface protrusion Height 2 detector type scanning electron microscope and cross-section measuring device sends the measured value of the height of the projection when scanning is performed with the height of the flat surface of the film being 0, and the film is sent to the image processing device. Reconstruct the surface protrusion image. The highest value among the binarized individual projections is defined as the height of the projection, and this is determined for each individual projection. This measurement was repeated 500 times at different locations, and the average value of the heights of all the measured protrusions was defined as the average height. As the magnification of the scanning electron microscope, a value between 1,000 and 10,000 times is selected.

(9) Young's modulus Measured at 25 ° C. and 65% RH using an Instron type tensile tester according to the method specified in JIS-Z-1702.

(10) Intrinsic viscosity [η] (unit: dl / g) The value calculated from the following formula from the solution viscosity measured in orthochlorophenol at 25 ° C is used. That is, η _SP / C = [η] + K [η] ² · C, where η _SP = (solution viscosity / solvent viscosity) -1, C is the solvent
Dissolved polymer weight per 100 ml (g / 100 ml, usually 1.2),
K is the Haggins constant (0.343). Also, solution viscosity,
The solvent viscosity was measured using an Ostwald viscometer.

(11) Scratch resistance Using a tape running tester, a film slit into a 1/2 inch wide tape is run on guide pins (surface roughness: 100 nm with Ra) (running speed 1,000 m /
Minutes, 10 passes, winding angle: 60 °, running tension: 65
g). At this time, observe the wound in the film with a microscope,
Excellent if less than 2 scratches with a width of 2.5 μm or more per tape width
More than 10 and less than 10 were judged as good, and more than 10 were judged as bad. Although excellent is desirable, even good is practically usable.

(12) Dubbing resistance A magnetic paint having the following composition is applied to the film with a gravure roll, magnetically oriented, and dried. Further, after calendering at a temperature of 70 ° C. and a linear pressure of 200 kg / cm using a small test calender (steel roll / nylon roll, 5 steps), curing is performed at 70 ° C. for 48 hours. The raw tape was slit into 1/2 inch to make a pancake. A length of 250 m from this pancake was incorporated into a VTR cassette to form 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 Using a home VTR for this tape, a TV test waveform generator produces 100% chroma A signal was recorded, and the chroma S / N was measured from the reproduced signal with a color video noise measuring device and designated as A. After dubbing the pancake of the master tape on which the same signal as described above was recorded to the pancake of the same sample tape (unrecorded) as in the measurement of A using a magnetic field transfer type video software high-speed printing system (sprinter) The chroma S / N of the tape was measured in the same manner as described above, and was designated as B. The decrease in chroma S / N (AB) due to this dubbing is 3
When the value was less than dB, the anti-dubbing property was excellent. When the value was 3 dB or more and less than 5 dB, the result was good. Yu is desirable,
Even if it is good, it can be used practically.

[Examples] The present invention will be described based on examples.

Examples 1 to 4 and Comparative Examples 1 to 5 Ethylene glycol was transesterified with dimethyl terephthalate, followed by polycondensation (thermoplastic resin A), and the thermoplastic resin A was functionalized on various surfaces in a vent-type molding machine. Polyethylene terephthalate containing 0.5 to 5% by weight of crosslinked polymer particles having functional group metal salts having different average particle diameters and heat resistances, to which water and organic compound slurries of crosslinked polymer particles having group metal salts are added. (Hereinafter referred to as PET) pellets were prepared. The intrinsic viscosity of this polymer is
It was 0.63. In addition, a thermoplastic resin B is produced by a conventional method by producing PET having an intrinsic viscosity of 0.64 and substantially not containing particles.
And These polymers were each dried under reduced pressure (3 Torr) at 180 ° C. for 6 hours. The thermoplastic resin A is supplied to the extruder 1 and melted at 285 ° C., and the thermoplastic resin B is further added to the extruder 2.
The polymer is melted at 280 ° C, and these polymers are combined and laminated in a confluence block (feed block), and then they are cooled and solidified by being wound around a casting drum with a surface temperature of 25 ° C using the electrostatic cast method to cool and solidify. An unstretched film of structure was made. At this time, an unstretched film was prepared with the ratio of die slit gap / unstretched film thickness being 10. Further, the discharge amount of each extruder was adjusted to adjust the total thickness and the thickness of the thermoplastic resin A layer. This unstretched film was stretched 3.5 times in the longitudinal direction at a temperature of 82 ° C. This stretching was performed in four stages with a difference in peripheral speed between two sets of rolls. This uniaxially stretched film was stretched 4.0 times in the width direction at 100 ° C at a stretching speed of 2,000% / min using a stenter and heat-treated at 210 ° C for 5 seconds under a constant length to give a total thickness of 10 µm and a thermoplastic resin A. Layer thickness 0.1-6 μm
Was obtained. The parameters of the present invention for these films are as shown in Table 1. When the parameters of the present invention were within the ranges, the scratch resistance and the dubbing resistance were excellent or good as shown in Table 1. However, otherwise, a film having both scratch resistance and dubbing resistance was not obtained.

[Advantages of the Invention] The present invention uses a thermoplastic resin containing a crosslinked polymer particle having a metal salt of a functional group and excellent in heat resistance by devising a manufacturing method to improve particle size and film thickness. Since the laminated film has a relationship, content, and film thickness within a specific range, the film has excellent scratch resistance, and also has excellent dubbing resistance when used for a magnetic recording medium. Therefore, it is possible to cope with an increase in the film processing speed in each application. Although the use of the film of the present invention is not particularly limited, it is particularly useful as a base film for a magnetic recording medium in which scratches on the film surface during the processing step are particularly problematic in the processing step and product performance. The two-layered film of the present invention has a thermoplastic resin A surface having a running surface (a surface not coated with a magnetic layer for a magnetic recording medium, and other applications such as printing and application of a coating material). It is preferable to use it as a surface that is not used.

Further, the laminated film of the present invention is a film produced by composite lamination directly in the film forming process without an operation such as coating, and has a surface layer higher than that of a laminated film formed by coating during or after the film forming process. Since the molecule is also biaxially oriented, other than the above-mentioned characteristics, for example,
The surface has much better abrasion resistance, and is advantageous in cost, quality stability, and the like.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C08L 25:06) B29K 67:00 B29L 9:00 (56) Reference JP-A-2-202924 ( JP, A) JP 62-225354 (JP, A) JP 61-217229 (JP, A) JP 1-129038 (JP, A) JP 2-214657 (JP, A)

Claims (4)

(57) [Claims] 1. Crosslinked polymer particles having a metal salt of a functional group and having a thermal decomposition temperature (10% weight loss temperature) of 380 ° C. or higher are provided on at least one surface of a film (B layer) containing a thermoplastic resin B as a main component. A film containing a thermoplastic resin A as a main component, which contains thermoplastic resin particles, wherein the average particle size of the particles 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 obtained by laminating a biaxially oriented thermoplastic resin film (A layer) having a thickness of 0.01 to 3 μm. 2. The biaxially oriented thermoplastic resin film according to claim 1, wherein the layer A is laminated on at least one surface of the layer B which does not substantially contain particles. 3. Particles having an average particle size of 0.1 to 2 .mu.m are 0.001 to 0.
The biaxially oriented thermoplastic resin film according to claim 1, wherein the layer A is laminated on at least one surface of the layer B containing 5% by weight. 4. A method of incorporating crosslinked polymer particles having a metal salt of a functional group into thermoplastic resin A, wherein the thermoplastic resin A is mixed with water and / or the boiling point of the crosslinked polymer particles using a venting molding machine. The method for producing a biaxially oriented thermoplastic resin film according to any one of claims (1) to (3), characterized in that an organic compound slurry at 200 ° C or lower is added.