JP2922070B2 - Biaxially oriented thermoplastic resin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially oriented thermoplastic resin film.

[0002]

2. Description of the Related Art As a biaxially oriented thermoplastic resin film, a film in which spherical silica particles are contained in polyester is known (for example, Japanese Patent Application Laid-Open No. Sho 59-1716).
No. 23).

[0003]

[Problems to be Solved by the Invention] However, the above-mentioned conventional biaxially oriented thermoplastic resin film becomes increasingly flat, for example, in order to obtain high output characteristics as a tape in a magnetic recording medium application. , During film formation,
There is a drawback that vertical wrinkling and winding deviation occur when winding into a roll at the time of slitting and winding at the time of tape production. Also, if the film surface is roughened to make it easy to wind up, the image quality when dubbing the resulting video tape or the like is deteriorated.
/ N (signal / noise ratio) was insufficient.

The present invention solves such a problem, and in particular, does not cause vertical wrinkles and winding deviations during high-speed winding (hereinafter referred to as excellent in winding characteristics), and has little deterioration in image quality during dubbing (hereinafter referred to as “dubbing resistance”). (Excellent).

[0005]

According to the present invention, there is provided a method for producing an image having a different average particle size.
A containing at least two types of particles
Layer (A layer) made of thermoplastic resin B
A biaxially oriented thermoplastic resin film laminated on at least one surface of the thermoplastic resin A,
The ratio t / d of the average particle diameter d of the particles contained in the particles is 0.1 to 5
And among the protrusions present on the surface of the layer A, the protrusion diameter is 0.7.
The number of protrusions of up to 2.6 μm is 100 to 10000 / m
m ² , and the ratio L / S of the number S of protrusions having a diameter of 0.2 μm to less than 0.7 μm to the number L of protrusions having a diameter of 0.7 μm to 2.6 μm is 1/50 to 1. / 10
000, which relates to a biaxially oriented thermoplastic resin film.

The thermoplastic resin A constituting the present invention is not particularly limited, such as polyester, polyolefin, polyamide, polyphenylene sulfide, etc., especially polyester, especially ethylene terephthalate, ethylene α, β.
When at least one structural unit selected from -bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate and ethylene 2,6-naphthalate units is a main component, the winding property and the anti-dubbing property are improved. It is desirable because it becomes even better. Further, the thermoplastic resin constituting the present invention is very desirable when it is crystalline or has optical anisotropy when melted, since the winding properties and the dubbing resistance are further improved. 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, winding properties and dubbing resistance are further improved, which is extremely desirable. In addition, two or more kinds of thermoplastic resins may be mixed or a copolymer may be used as long as the present invention is not hindered.

The particles in the thermoplastic resin A of the present invention have a particle diameter ratio (particle major axis / minor axis) of from 1.0 to 1.3, and particularly, in the case of spherical particles, the winding property and the resistance are improved. It is desirable because the dubbing property is further improved.

[0008] (smallest particles having an average particle diameter) of at least two kinds of particles P in the thermoplastic resin A of the present invention, allowed to contain Q (largest particles having an average particle diameter). However, in order to improve the winding characteristics, at most five or less types are desirable. In order to satisfy the above-mentioned film, the particles P are preferably alumina silicate, silica in which primary particles are aggregated, internally precipitated particles, and the like, and substantially spherical silica particles due to colloidal silica, crosslinked organic particles Such a case is particularly desirable because the winding characteristics and the dubbing resistance are further improved. However, other particles, such as particles of calcium carbonate, titanium dioxide, alumina, etc., can be sufficiently used by appropriately controlling the film thickness and the average particle size. When the particles Q are crosslinked organic particles, the winding properties and the dubbing resistance are further improved, which is particularly desirable. Examples of the crosslinked organic particles include crosslinked polydivinylbenzene particles, crosslinked polystyrene particles, crosslinked polyester particles, crosslinked polyimide particles, crosslinked polyethersulfone particles, and the like. Further, the crosslinked organic particles have a particle surface having a general formula -CO such as polyacrylic acid, sodium polyacrylate, or sodium polymethacrylate.
It is particularly desirable when coated with a polymer having a functional group represented by OX (X is H, an alkyl group, an alkali metal or an alkaline earth metal), since the winding properties and the dubbing resistance are further improved. Further, it is desirable to coat with a polymer represented by the general formula -COOX together with a copolymer or blend of another polymer, since the winding properties and the dubbing resistance are further improved. Further, it is preferable that the particles do not substantially react with the thermoplastic resin A and the polymer coating the surface of the particles. Particles that do not substantially react are particles that do not cause a chemical reaction with the surrounding polymer or thermoplastic resin A and do not have a chemical bond such as a covalent bond or an ionic bond. When the particles and the surrounding polymer or the thermoplastic resin A do not strongly react with each other, it is particularly preferable because the particles in the thermoplastic resin A do not agglomerate and the winding properties and the dubbing resistance are further improved. It is particularly desirable to add a dispersant together with the particles because the aggregation of the particles is prevented and the winding properties and the dubbing resistance are further improved.

The thickness t of the A layer made of the thermoplastic resin A of the present invention and the average particle size d of the particles contained in the thermoplastic resin A
Must be 0.1 to 5, preferably 0.2 to 2.5, and more preferably 0.3 to 1.0. If the value of t / d is smaller than the above range, the winding property becomes poor, and if it is larger, the anti-dubbing property becomes poor, which is not preferable.

The average particle size d of the particles in the thermoplastic resin A is not particularly limited, but is 0.02 to 1.0 μm, particularly 0.05
When the thickness is in the range of about 0.8 μm, the winding properties and the anti-dubbing property are further improved, which is desirable.

The particles in the thermoplastic resin A of the present invention have a particle size ratio (major particle diameter / minor particle diameter) of 1.0 in the film.
Particles having a diameter of from 1.3 to 1.3, particularly spherical particles, are desirable because the winding properties and the anti-dubbing property are further improved.

The content of particles in the thermoplastic resin A of the present invention is 0.2 to 15% by weight, preferably 0.5 to 10% by weight, more preferably 1 to 8% by weight based on the total weight of the A layer. % And the ratio Pw / Qw of the weight% of the particles P to the particles Q is 4
When it is from 400 to 400, and more preferably from 6 to 250, the winding property and the anti-dubbing property are further improved.

The main component of the film of the present invention is a composition comprising the above-mentioned thermoplastic resin A and at least two kinds of particles having different average particle diameters. And organic additives such as antioxidants, heat stabilizers, lubricants, and ultraviolet absorbers may be added to the extent that they are usually added.

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 preferable because the winding characteristics are poor. 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 350 kg in both the longitudinal and width directions.
/ Mm ² or more is very desirable because the winding characteristics are further improved. The upper limit of the Young's modulus, which is a measure of the degree of molecular orientation, is not particularly limited, but is usually 1500 kg.
/ Mm ² is the manufacturing limit.

In addition, even when the Young's modulus is within the above range, the orientation of polymer molecules in the thickness direction of the film, for example, near the surface layer, is not non-oriented or uniaxial, ie, the entire film in the thickness direction. In particular, when the molecular orientation is biaxial orientation, the winding property and the anti-dubbing property are further improved, which is particularly desirable.

In particular, when the molecular orientation measured by an Abbe refractometer, a refractometer using a laser, a total reflection laser Raman method or the like is biaxial on both the front surface and the back surface, the winding characteristics and the dubbing resistance are further improved. It is particularly desirable because it becomes good.

Further, the thermoplastic resin A is a crystalline polyester, and its surface has a total reflection Raman crystallization index of 20 c.
m ⁻¹ or less, preferably 18 cm ⁻¹ or less, and more preferably 17
It is very desirable that the diameter is less than cm ^{-1 because the} winding properties and the dubbing resistance are further improved.

It is particularly desirable that the thickness of the thermoplastic resin A film of the present invention is 0.01 to 3 μm, particularly 0.05 to 1 μm, because the winding properties and the dubbing resistance are further improved.

The average height of protrusions on the surface of the thermoplastic resin A film of the present invention is 10 to 800 nm, especially 20 to 500 nm.
It is particularly preferable that the particle diameter is in the range of nm because the winding properties and the dubbing resistance are further improved.

The number of protrusions having a diameter of 0.7 to 2.6 μm on the surface of the film made of the thermoplastic resin A of the present invention is 10
0 to 10000 pieces / mm ² , preferably 300 to 900
0 / mm ² , more preferably 500-8000 /
It needs to be in the range of mm ² . The projection diameter is 0.7
When the number of protrusions of about 2.6 μm is smaller than the above range, the winding property is poor, and when it is large, the dubbing resistance is poor, which is not preferable.

Here, the ratio L / S of the number of projections S having a diameter of 0.2 μm to less than 0.7 μm and the number L of projections having a diameter of 0.7 μm to 2.6 μm is 1/50 to 1 /. / 1
0000. Preferably, L / S is 1/70 to 1/5000, and more preferably, L / S is 1
In the case of / 100 to 1/3000, the winding characteristics are particularly good.

The total number of protrusions on the surface of the film made of the thermoplastic resin A of the present invention is 100,000 to 1,000,000 / mm ² , preferably 150,000 to 900,000 / mm ² , more preferably 20
It is particularly desirable when the number is in the range of 10,000 to 800,000 pieces / mm ² , since the winding property and the anti-dubbing property are further improved.

As described above, it is highly desirable that the thermoplastic resin constituting the film of the present invention is crystalline or melt optically anisotropic. However, in the case of a melt isotropic film, the crystallization parameter ΔTcg is 25 to When the temperature is 65 ° C., the winding characteristics are further improved, which is particularly desirable.

When the thermoplastic resin A is a polyester, it is particularly preferable that the thickness direction refractive index of the surface of the thermoplastic resin A is 1.5 or less, since the winding property and the dubbing resistance are further improved. Furthermore, the intrinsic viscosity of the film is 0.60
As described above, it is particularly desirable that the winding property is further improved, especially when it is 0.70 or more.

As the thermoplastic resin B, a crystalline polymer is desirable, and in particular, the crystalline parameter ΔTcg is 20 to 100.
When the temperature is in the range of ° C., the winding characteristics are further improved, which is desirable. As specific examples, polyester, polyamide,
Examples thereof include polyphenylene sulfide and polyolefin. Among them, polyester is particularly preferable because winding properties are further improved. Further, 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 unit is a main constituent. When it is a component, it is desirable because the dubbing resistance becomes particularly good.
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%. In addition, thermoplastic resin B
And A may be the same or different.

The thermoplastic resin B of the present invention may be blended with other polymers as long as the object of the present invention is not impaired, and may be used in combination with antioxidants, heat stabilizers, lubricants, ultraviolet absorbers and the like. Organic additives may be added to the extent that they are usually added.

The layer made of the thermoplastic resin B does not need to contain particles in particular, but has an average particle size of 0.01 to 1 μm,
In particular, particles of 0.03 to 0.5 μm are added in an amount of 0.001 to 0.8.
If it is contained in an amount of 0.005 to 0.6% by weight, the winding properties are further improved, so that it is very desirable. It is desirable to use the kind of particles contained in the thermoplastic resin A that is desirably used. The types and sizes of the particles contained in the thermoplastic resins A and B may be the same or different.

The difference (A−B) between the crystallization parameters ΔTcg of the thermoplastic resin A and the thermoplastic resin B is not particularly limited. However, when the temperature is −30 to + 20 ° C., the winding characteristics and the anti-dubbing property are further improved. This is particularly desirable.

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

First, as a method for incorporating particles into the thermoplastic resin, when the thermoplastic resin is a polyester, it is dispersed in the form of a slurry of ethylene glycol as a diol component, and the ethylene glycol is mixed with a predetermined dicarboxylic acid component. It is effective to obtain a film having a relationship between the thickness and the average particle diameter within the range of the present invention. Also, the crystallization parameter ΔTcg is adjusted to 4 by adjusting the melt viscosity, copolymerization component and the like of the polyester containing the particles.
The method in which the temperature is kept in the range of 0 to 65 ° C. is effective for obtaining a film having a relationship between the thickness and the average particle diameter in the range of the present invention.

The method of heat-treating a slurry of particles of ethylene glycol at a temperature of 140 to 200 ° C., particularly 180 to 200 ° C., for 30 minutes to 5 hours, and particularly for 1 to 3 hours, has a thickness and an average particle size within the range of the present invention. It is effective to get the connection film.

As another method for incorporating particles into the thermoplastic resin, the particles are heat-treated in ethylene glycol, mixed with the thermoplastic resin in the form of a slurry in which the solvent is replaced with water, and then subjected to a twin-screw extrusion of a vent method. A method of kneading with a kneading machine and kneading the mixture with a thermoplastic resin is also extremely effective for obtaining a film having a relationship between the thickness and the average particle diameter in the range of the present invention.

As a method for adjusting the content of particles, a high-concentration master is prepared by the above-described method, and the master is diluted with a thermoplastic resin containing substantially no particles during film formation to adjust the content of particles. Is effective. As a method of incorporating at least two kinds of particles into a thermoplastic resin, a method of dispersing at least two kinds of particles in advance in the form of a slurry of a diol component and polymerizing the same with a predetermined dicarboxylic acid component as described above, or As described above, any of the methods for preparing a high-concentration master polymer containing each particle and adjusting the content of each particle during film formation can be used.

Thus, a pellet containing at least two kinds of particles in a predetermined amount is dried if necessary. Next, the following method is effective as a method of laminating a film made of the thermoplastic resin A on at least one surface of the film made of the thermoplastic resin B.

The thermoplastic resins A and B are supplied to a known extruder for melt lamination, extruded into a sheet 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 a relationship between the thickness and the average particle diameter in the range of the present invention.

Next, the 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, but a sequential biaxial stretching method in which stretching is performed in the longitudinal direction first and then in the width direction is preferable. It is effective to obtain a film having a relationship between the thickness and the average particle size within the range of the present invention by performing the method in which the total longitudinal stretching ratio is 3.0 to 6.5 times divided into stages or more.
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 longitudinal stretching temperature varies depending on the type of the thermoplastic resin and cannot be unconditionally determined.
In the second and subsequent stages, setting the height higher than that is effective for obtaining a film having a relationship between the thickness and the average particle diameter in the range of the present invention. The longitudinal stretching speed is 5000 to 50,000% / mi
The range of n is preferred. As a stretching method in the width direction, a method using a stenter is generally used, and the stretching ratio is 3.0 to 3.0.
A range of 5.0 times is appropriate. Stretching speed is 1000-2
0000% / min, 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 150 to 220 ° C., particularly 170 to 21 ° C.
0 ° C. and the time are preferably in the range of 0.5 to 60 seconds.

In the present invention, the distribution of the diameter of the protrusions present on the surface of the layer A is defined as a specific range, and the relationship between the thickness of the layer and the average particle diameter is defined as a specific range.
It is also presumed that the effects of the present invention were obtained as a result of improving the dispersibility of the particles.

[0038]

[Method for measuring physical properties and method for evaluating effects] The method for measuring characteristic values and the method for evaluating effects 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 peak of the particle size distribution was determined by the following formula for a clearly narrow specific particle size.

Further, if measurement is difficult with this method,
A film containing particles having different average particle diameters is formed into an ultra-thin section of about 1000 to 8000 angstroms in the thickness direction, and a thin film is obtained by using a transmission electron microscope (for example, JEM-1200EX manufactured by JEOL Ltd.).
The particles were observed at a magnification of about 000 to 200,000, and determined by the following equation.

The number average diameter D was defined as the average particle diameter. D = ΣDi / N Here, Di is the equivalent circle diameter of the particles, and N is the number.

(2) Particle size ratio In the measurement of the above (1), the average value of the major axis of each particle /
It is the ratio of the average value of the minor axis. 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), the minor axis (shortest axis) of each particle, and N is the total number.

(3) Content of particles 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 (% by weight) to the total weight of the particles is defined as the particle content. In some cases, the combined use of infrared spectroscopy is also effective.

(4) Laminate thickness of thermoplastic resin A layer Using a secondary ion mass spectrometer (SIMS), this is due to the highest concentration of particles in the film in a range of 3000 nm from the surface layer to the depth. The concentration ratio (M ⁺ / C ⁻ ) between the element and the carbon element of the polyester is defined as the particle concentration, and the analysis in the thickness direction is performed from the surface to a depth of 3000 nm. In the surface layer, the particle concentration is low due to the interface of the surface, and the particle concentration increases as the distance from the surface increases. In the case of the film of the present invention, the particle concentration which has once reached a maximum value starts to decrease again.
Based on this concentration distribution curve, the depth at which the surface layer particle concentration is の of this maximum value (this depth is deeper than the depth at which the maximum value is obtained) was determined, and this was defined as the lamination thickness. The conditions are as follows.

Measuring device Secondary ion mass spectrometer (SIMS) ATOMI, Germany
A-DIDA3000 manufactured by KA Measurement conditions Primary ion species 0 ₂ ⁺ Primary ion acceleration voltage 12 kV Primary ion current 200 nA Raster area 400 μm □ Analysis area Gate 30% Measurement vacuum degree 5.0 × 10 ⁻⁹ Torr E-GUN 0 In the case where the particles most contained in the range from the surface layer to the depth of 3000 nm are crosslinked organic particles, it is difficult to measure by SIMS. Therefore, XPS (X-ray photoelectron spectroscopy) and IR while etching from the surface layer are performed. (Infrared spectroscopy) or the like to measure the depth profile similar to the above, and obtain the lamination thickness.
The lamination thickness can also be determined by recognizing the interface from a change in the particle concentration or a difference in contrast by cross-sectional observation using an electron microscope or the like.

(5) Crystallization parameter ΔTcg, heat of fusion 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 temperature of the quenched sample is raised at 10 ° C./min, and the glass transition point Tg is detected. Continue heating up further,
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.

(6) Surface molecular orientation (refractive index), surface total reflection Raman crystallization index Measured with an Abbe refractometer using sodium D line (589 nm) as a light source. 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 setting the refractive index in the longitudinal, width, and thickness directions to N.
Assuming that the absolute value of (N1 -N2) is not more than 0.07 and N3 / {(N1 + N2) / 2} is not more than 0.95 when 1, N2 and N3 are set as one criterion. 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. Measurement of laser total reflection Raman was performed by Raman manufactured by Jobin-Yvon.
The or U-1000 Raman system measures the total reflection Raman spectrum, for example in the case of polyethylene terephthalate, (skeletal vibration of benzene ring) 1615 cm ^-1 and 1730 cm ^{- 1} (stretching vibration of carbonyl group)
The polarization measurement ratio of the band intensity ratio (YY / XX ratio etc., where YY: Raman polarization direction of laser is set to Y and Raman light parallel to Y is detected, XX: Polarization direction of laser is set to X and X And parallel Raman light detection) 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, the 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 (5145A) 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 6
0 °. Detector PM: RCA31034 / Photon County
ng System (Hamamatsu C123
0) (supply 1600 V) Measurement conditions SLIT 1000 μm LASER 100 mW GATE TIME 1.0 sec SCAN SPEED 12 cm ⁻¹ /
min SAMPLING INTERVAL 0.2cm ^-1 REPERT TIME 6

(7) Diameter, number, and height of surface protrusions A two-detector scanning electron microscope [ESM-3200,
Elionix Co., Ltd.] and a cross section measuring device [PMS-1,
Elionix Co., Ltd.], the measured height of the projection when scanning was performed with the height of the flat surface of the film set to 0, and an image processing apparatus [IBAS2000, Carl Zeiss Co., Ltd.]
And reconstruct a film surface projection image on an image processing apparatus. Next, a circle-equivalent diameter is obtained from the area of each projection obtained by binarizing the projection portion with this surface projection image, and this is defined as the projection diameter. The number of projections having a projection diameter of 0.7 to 2.6 μm is calculated. Count. The highest value among the binarized individual projections is defined as the height of the projection, and this is determined for each individual projection. Change this measurement to 5
Repeated 00 times, counting all the measured protrusions,
The value calculated per 1 mm ² was defined as the number of protrusions. The average value of the height was defined as the average height. As the magnification of the scanning electron microscope, a value between 1000 and 10000 times is selected.

(8) Young's modulus According to the method specified in JIS-Z-1702,
Using an Instron type tensile tester, 25 ° C,
It was measured at 65% RH.

(9) Intrinsic viscosity [η] (unit: dl / g) A value calculated from the following formula based on 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, and C is the weight of dissolved polymer per 100 ml of solvent (g / 100 ml,
Usually 1.2), K is a Haggins constant (0.343). The solution viscosity and the solvent viscosity were measured using an Ostwald viscometer.

(10) Winding Characteristics The film was wound up on a roll having a width of 1000 mm and a length of 18000 m (speed: 300 m / min), and the end face deviation and vertical wrinkling of the roll were inspected in detail and judged as follows. . End face displacement (distance of displacement in the width direction) is 0.5
mm, no vertical wrinkles and no defects such as vertical wrinkles even after standing for 24 hours or more: excellent, immediately after roll winding, end face deviation is less than 0.5 mm, and no vertical wrinkles Visually showing vertical wrinkles visually after standing for more than an hour: good, good when the end face deviation is 0.5 mm or more, or slightly vertical wrinkles immediately after winding the roll: poor. Although excellent is desirable, even good is practically usable.

(11) Dubbing resistance A magnetic paint having the following composition is applied to the film with a gravure roll, magnetically oriented, and dried. In addition, a small test calendar device (steel roll / nylon roll,
After performing a calendering process at a temperature of 70 ° C. and a linear pressure of 200 kg / cm, curing is performed at 70 ° C. for 48 hours. The raw tape was slit into 1/2 inch to prepare 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 Parts-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 TV test waveform generation using this tape with a home VTR A 100% chroma signal is recorded by a colorimeter, and the chroma S / N is measured from the reproduced signal with a color video noise measuring device, and A
And 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 above.
And Reduction of chroma S / N by this dubbing (A-
When B) was less than 3 dB, the anti-dubbing property was excellent. When it was 3 dB or more and less than 5 dB, it was judged as good, and when 5 dB or more was bad. Although excellent is desirable, even good is practically usable.

[0055]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on embodiments.

Examples 1 and 2 First, a thermoplastic resin A is prepared. Prepare an ethylene glycol slurry containing silica particles derived from colloidal silica having different average particle diameters as particles P and Q, heat-treat this ethylene glycol slurry at 190 ° C. for 2 hours, and subject it to a transesterification reaction with dimethyl terephthalate,
Polycondensation was performed to produce a polyethylene terephthalate chip containing the particles in a predetermined amount. This chip was designated as thermoplastic resin A. Next, polyethylene terephthalate containing no particles was produced by a conventional method, and was used as thermoplastic resin B.

Each of these polymers was dried under reduced pressure (3 Torr) at 180 ° C. for 3 hours. The thermoplastic resin A is supplied to the extruder 1 and melted at 290 ° C.
Is supplied to the extruder 2 and melted at 280 ° C., and these polymers are combined and laminated by a combined block (feed block).
The film was wound around a casting drum having a surface temperature of 25 ° C. using an electrostatic application casting method, and cooled and solidified to form an unstretched film having a two-layer structure. Further, the discharge amount of each extruder was adjusted to adjust the total thickness, the thickness of the thermoplastic resin A layer and t /
d was adjusted. This unstretched film was stretched 3.6 times in the longitudinal direction at a temperature of 85 ° C. This stretching was performed in four stages with a difference in peripheral speed between two sets of rolls. This uniaxially stretched film is stretched at a stretching speed of 2000% / min using a stenter at 95 ° C.
And stretched 4.0 times in the width direction at 210 ° C. under constant length.
Heat treatment was performed for 2 seconds to obtain a biaxially oriented laminated film having a total thickness of 10 μm. The parameters of the invention for these films are shown in Table 1.
And the parameters were within the scope of the present invention, and good film properties were obtained.

Example 3 A biaxially oriented laminated film was obtained in the same manner as in Examples 1 and 2, using calcium carbonate particles as particles P and colloidal silica particles as particles Q. The parameters of the present invention are as shown in Table 1.

Examples 4 and 5 A thermoplastic resin A was prepared using colloidal silica particles having a predetermined average particle diameter as the particles P and crosslinked polydivinylbenzene particles as the particles Q. Here, the method for adding the crosslinked polydivinylbenzene particles is described in Example 1,
The colloidal silica-containing chip obtained in the same manner as in Example 2 was supplied to a vent-type twin-screw kneading extruder, and crosslinked polydivinylbenzene particles dispersed in water were added in the form of a slurry. A method was used in which the particles were kneaded while being pushed out. Using the thermoplastic resin A thus obtained, a biaxially oriented laminated film was obtained in the same manner as in Example 1 and Example 2. Table 1 shows the parameters of the present invention.
As shown.

Example 6 A biaxially oriented laminated film was obtained in the same manner as in Examples 1 and 2, using calcium carbonate particles as particles P and crosslinked polydivinylbenzene particles as particles Q. The parameters of the present invention are as shown in Table 1.

Examples 7 and 8 A biaxially oriented laminated film was obtained in the same manner as in Examples 1 and 2, using colloidal silica particles as the particles P and crosslinked polystyrene particles as the particles Q. The parameters of the present invention are as shown in Table 1.

Examples 9 and 10 Biaxially oriented laminated films were obtained in the same manner as in Examples 1 and 2, using crosslinked polydivinylbenzene particles having different average particle sizes as the particles P and Q. The parameters of the present invention are as shown in Table 2.

Comparative Example 1 A biaxially oriented laminated film was obtained in the same manner as in Examples 1 and 2, using colloidal silica particles having different average particle sizes as the particles P and Q. The parameters are as shown in Table 2. Here, when the addition amount of the particles Q was too large, both the winding characteristics and the dubbing resistance were poor.

Comparative Examples 2 and 3 Biaxial orientation was carried out in the same manner as in Examples 1 and 2, using colloidal silica particles having a predetermined average particle size as particles P and crosslinked polydivinylbenzene particles as particles Q. A laminated film was obtained. The parameters are as shown in Table 2. In both cases, t / d was out of the range of the present invention, and a film having both winding properties and anti-dubbing properties was not obtained.

Comparative Example 4 A biaxially oriented laminated film was obtained in the same manner as in Examples 1 and 2, using colloidal silica particles as particles P and crosslinked polystyrene particles as particles Q. The parameters are as shown in Table 2. Here, since the number of projections caused by the large-diameter particles was too small, the winding characteristics were poor.

Comparative Example 5 A biaxially oriented laminated film was obtained in the same manner as in Examples 1 and 2, using calcium carbonate particles as particles P and crosslinked polydivinylbenzene particles as particles Q. The parameters are as shown in Table 2. The value of L / S was out of the range of the present invention, and both the winding property and the dubbing resistance were poor.

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[Table 1]

[Table 2]

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According to the present invention, at least different average particle sizes are used.
The relationship between the layer thickness and the average particle diameter of the thermoplastic resin containing two types of particles, and the number of projections having a large projection diameter are in a specific range, so that a film having excellent winding characteristics and anti-dubbing properties is obtained.
When winding the film into a roll in a slit or processing step, it is easy to wind without wrinkles and end face deviation,
Therefore, it is possible to cope with an increase in the film transport speed in each step. The use of the film of the present invention is not particularly limited, but when used as a base film for a magnetic recording medium, high output characteristics can be obtained, which is particularly useful for improving the quality of video tapes in the future. In addition to the magnetic recording medium described above, the present invention can be widely applied to various uses such as a capacitor utilizing good electrical insulation and a packaging utilizing good transparency. In addition, 2 of the films of the present invention
In the case of the layered structure, the surface of the thermoplastic resin A layer has a non-functional surface (for a magnetic recording medium, a surface on which a magnetic layer is not applied, and for other uses, a surface on which no processing such as printing or other application of a coating material is applied). ) Is desirable.

Claims (6)

(57) [Claims] 1. A layer (A layer) made of thermoplastic resin A containing at least two kinds of particles having different average particle diameters, and at least one surface of a layer (B layer) made of thermoplastic resin B A biaxially oriented thermoplastic resin film laminated on
The ratio t / d of the thickness t of the layer to the average particle diameter d of the particles contained in the thermoplastic resin A is 0.1 to 5, and the protrusion diameter of the protrusions present on the surface of the layer A is 0.7 μm or more. The number of projections having a diameter of 2.6 μm or less is 100 to 10000 / mm ² , and the number S of projections having a diameter of 0.2 μm or more and less than 0.7 μm.
A ratio L / S of the number L of projections having a diameter of 0.7 μm to 2.6 μm is 1/50 to 1/10000, and a biaxially oriented thermoplastic resin film. 2. The biaxially oriented thermoplastic resin film according to claim 1, wherein the total number of protrusions on the surface of the layer A is 100,000 to 2,000,000 / mm ² . 3. The biaxially oriented thermoplastic resin film according to claim ² , wherein the total number of projections on the surface of the layer A is 150,000 to 900,000 / mm ² . 4. The particles having the largest average particle diameter in the layer A are present.
The biaxial orientation according to claim 1, wherein the particles are machine particles.
Thermoplastic resin film. 5. The method according to claim 1, wherein the organic particles are crosslinked organic particles.
5. The biaxially oriented thermoplastic resin fill according to claim 4,
M 6. The crosslinked polydivinylbenze according to claim 6, wherein the crosslinked organic particles are crosslinked polydivinylbenzene.
6. The biaxial orientation according to claim 5, wherein
Thermoplastic resin film.