JPH03209622A - Video tape for high-density recording - Google Patents

Abstract

PURPOSE:To enhance scratch resistance and dubbing resistance by using a thermoplastic resin contg. particles and specifying the relation between the size of particles and the thickness of a film, the content, the relation between the standard deviation of the height distribution of surface projections on a nonmagnetic surface and the number of the projections, etc. CONSTITUTION:This video tape consists of the biaxially oriented thermoplastic resin film having a film layer A to form the nonmagnetic surface and a magnetic layer. The standard deviation sigma of the height distribution of the surface projections on this magnetic surface and the number N of the projections exceeding 225nm height is 0<=(3sigma-225)N<5X10<4>. The scratch resistance and dubbing resistance are degraded if the values are off this range. The film layer A consists essentially of the thermoplastic resin A and the particles and the thickness thereof is 0.005 to 3mum. In addition, the average grain size of the particles incorporated into the film layer A is 0.1 to 10 times the thickness of the film layer A. Further, the content of the particles is 0.5 to 50wt.%. The effect is not obtainable if this range is exceeded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-density recording videotape.

[Prior Art] Magnetic recording tapes have made remarkable progress in recent years, but the demand for video tapes has increased rapidly with the spread of home video tape recorders, and as a result, the demand for higher-performance models has increased. ing.

In particular, there have been remarkable advances in technology for high-density recording.
Improvements have been made in both the magnetic layer and the base film. Improvements to the magnetic layer include coating type, electroplating,
Attempts have been made to reduce the thickness of the magnetic layer by methods such as electroless plating, vacuum deposition, sputtering, and ion blating. On the other hand, improvements have been made to the base film, including improvements in its surface morphology and surface properties, as well as improvements in the mechanical properties of the film (Japanese Patent Laid-Open Publication No. 80825/1984, etc.).

[Problems to be solved by the invention] However, the base film described above is still insufficient for high-density recording applications that require harsh characteristics, and the process speed of dubbing and manufacturing soft tapes etc. As the number of magnets increases, there has been a drawback that the non-magnetic surface is scratched by the rolls and guides that come into contact with it.

Furthermore, due to the deterioration in image quality during dubbing, the image quality, that is, the S/N (signal/noise ratio) was also insufficient.

The present invention solves the drawbacks of the prior art, and the non-magnetic surface of the tape is less likely to be scratched (hereinafter referred to as "excellent scratch resistance") especially during high-speed processes, and there is less deterioration in image quality during dubbing (hereinafter referred to as "excellent scratch resistance"). The aim is to provide a high-density recording videotape (which is said to have excellent performance).

[Means for Solving the Problems] The present invention comprises a biaxially oriented thermoplastic resin film having a film layer A forming a non-magnetic surface and a magnetic layer, and the height distribution standard deviation σ of surface protrusions on the non-magnetic surface is (n m
) and the number of protrusions with a height exceeding 225 nm N (pieces/mm2)
is O≦(3σ-225)N<5X104, the film layer A is mainly composed of thermoplastic resin A and particles and has a thickness of 0.005 to 3 μm, and the film layer A The average particle diameter of the particles contained therein is 0.1 to 10 times the thickness of the film layer A, and the content of the particles is 0.5 to 10 times the thickness of the film layer A.
50% by weight of a high-density recording videotape.

The thermoplastic resin A constituting the present invention is not particularly limited to polyester, polyolefin, polyamide, polyphenylene sulfide, etc., but in particular, polyester, polyphenylene sulfide, etc.
Among them, when the main constituent component is at least one structural unit selected from ethylene terephthalate, ethylene α, β-bis(2-chlorophenoxy)ethane-4,4′-dicarboxylate, and ethylene 26-naphthalate units. This is desirable because it provides even better scratch resistance and dubbing resistance. Further, it is extremely desirable that the thermoplastic resin constituting the present invention be crystalline or optically anisotropic when melted, since this will further improve scratch resistance and dubbing resistance. Crystallinity here indicates that it is not so-called amorphous, and quantitatively, the cold crystallization temperature Tcc in the crystallization parameter is detected, and the crystallization parameter ΔTcg is 150°C or less. be. Furthermore, it is extremely desirable that the heat of fusion (change in enthalpy of fusion) measured by a differential scanning calorimeter exhibits crystallinity of 7.5 cal/g or more, since scratch resistance and dubbing resistance will be even better. Further, polyester containing ethylene terephthalate as a main component is particularly desirable because it has even better dubbing resistance and scratch resistance. In addition, within the range that does not impede the present invention, 2
More than one type of thermoplastic resin may be mixed, or a copolymer may be used.

The particles in the thermoplastic resin A of the present invention have a particle size ratio (longer diameter/breadth diameter) of 1.0 to 1.3 in the film layer A, especially spherical particles. This is desirable because the scratch resistance becomes even better.

Further, the particles in the thermoplastic resin A of the present invention are contained in the film layer A.
The single particle index within is 0. 7 or more, preferably 0.
A value of 9 or more is particularly desirable because scratch resistance and dubbing resistance become even better.

Further, the particles in the thermoplastic resin A of the present invention have a relative standard deviation of 0.6 or less, preferably 0.5 in the film layer A.
The following cases are desirable because the scratch resistance and dubbing resistance become even better.

The type of particles in the thermoplastic resin A of the present invention is not particularly limited, but in order to satisfy the above preferable particle characteristics, alumina silicate, silica in a state where primary particles are aggregated, internally precipitated particles, etc. are not preferred ( , substantially spherical silica particles caused by colloidal silica, and particles made of crosslinked polymers (e.g. crosslinked polystyrene).
Measured using M. It is particularly desirable to use crosslinked polymer particles in which the degree of crosslinking is increased to a temperature increase rate of 20°C/min) of 380°C or higher, since the scratch resistance and dabbing resistance will be even better. Note that in the case of spherical silica derived from colloidal silica, substantially spherical silica with a low sodium content produced by an alkoxide method is particularly desirable because the scratch resistance is even better. However, other particles, such as particles of calcium carbonate, titanium dioxide, alumina, etc., can also be used satisfactorily with proper control of film thickness and average particle size.

The crystallization promotion coefficient of the particles in the thermoplastic resin A of the present invention is not particularly limited, but is -15 to 15°C, preferably -5°C.
A temperature of 10° C. to 10° C. is particularly desirable because the scratch resistance becomes even better.

Regarding the particle size, the average particle diameter in film layer A is 0.1 to 10 times the thickness of film layer A, preferably 0.5 to 5.
It needs to be in the range of 1.1 to 3 times, more preferably 1.1 to 3 times. If the average particle diameter/thickness ratio of the film layer A 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.

Further, the average particle size (diameter) of the particles in the thermoplastic resin A in the film layer A is 0.007 to 1.0 μm1, preferably 0.
．． A thickness in the range of 0.02 to 0.8 μm is desirable because scratch resistance and dubbing resistance become even better.

The content of particles in the thermoplastic resin A of the present invention is 0.5 to 5.
It is necessary that the amount is 0% by weight, preferably 1 to 30% by weight, and more preferably 2 to 15% by weight. If the content of the particles is less than the above range, or conversely if it is greater than the above range, the scratch resistance will be poor, so it is not preferable.

The main component of the film layer A of the present invention is a composition consisting of the thermoplastic resin A and 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.

Film layer A 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.

In addition, the film layer A of the present invention has a part in the thickness direction of the film, for example, the orientation of the polymer molecules near the surface layer is non-oriented or -axially oriented, that is, in the entire thickness direction. It is particularly desirable that the molecular orientation 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 of the film layer A of the present invention containing this as a main component is 2Qcm-1 or less, preferably 18
cm' or less, more preferably 17 cm1 or less, is extremely desirable because scratch resistance and dubbing resistance are even better.

The surface layer particle concentration ratio measured by the secondary ion mass spectrum of the film layer A mainly composed of the thermoplastic resin A of the present invention is not particularly limited, or is 1/10 or less, especially 11
When it is 50 or less, the scratch resistance becomes even better, so it is particularly desirable.

The thickness of the film layer A mainly composed of the thermoplastic resin A of the present invention is 0.005 to 3 μm, preferably 0.01 to 1 μm.
It is necessary that m1 is more preferably 0.03 to 0.5 μm. If the film thickness is smaller than the above range, the dubbing resistance will be poor, and if it is larger than the above range, the scratch resistance will be poor, which is not preferable.

The average protrusion height on the surface of the film layer A containing the thermoplastic resin A of the present invention as a main component is 5 to 500 nm.

Preferably 10-300 nm, more preferably 15-300 nm
A range of 200 nm is particularly desirable because scratch resistance and dubbing resistance become even better.

It is particularly desirable that the average distance between the protrusions of the film layer A containing the thermoplastic resin A of the present invention as a main component is 6 μm or less, preferably 4 μm or less, since the scratch resistance and dubbing resistance will be even better.

The centerline depth Rp of the surface of the film layer A mainly composed of the thermoplastic resin A of the present invention is not particularly limited, but Rp is 1
．． A thickness of 80 nm or less, especially 160 nm or less is particularly desirable because the dubbing resistance becomes even better. Further, the ratio of the above Rp to the maximum height Rt, Rt/Rp, is 1.
5 to 2.5, especially 1.degree. to 2.3, which is particularly desirable because scratch resistance and dubbing resistance become even better.

The ratio of the center line average roughness Ra to the maximum height Rt of the surface of the film layer A mainly composed of the thermoplastic resin A of the present invention, Rt
/Ra is 9.0 or less, especially 8.5 or less, as this is particularly desirable since scratch resistance and dubbing resistance become even better.

As mentioned above, it is extremely desirable that the thermoplastic resin constituting the film layer A of the present invention be crystalline or melt-optically anisotropic, but in the case of a melt-isotropic film, the crystallization parameter ΔTcg is 25 to 65. ℃ is particularly desirable because the scratch resistance becomes even better.

In addition, when the thermoplastic resin A is polyester, it is particularly desirable that the refractive index of the thermoplastic resin A surface in the thickness direction is 1.5 or less, since scratch resistance and dubbing resistance become even better.

When the thermoplastic resin A constituting the film layer A of the present invention is polyester, it is particularly preferable that the intrinsic viscosity of the film is 0.60 or more, particularly 0.70 or more because the scratch resistance will be even better.

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

The above is a case where the laminated structure is Layer A/Layer B/Layer A, Layer A/Layer B, but of course, Layer A/Layer is provided with Layer C having a different surface condition from Layer A on the opposite side of Layer A. It may be B/layer C or a multilayer structure of more layers. (Here, the types of thermoplastic resins in the layers A, B, and C may be the same or different.

Further, at least one surface needs to be layer A. ) 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, as a polyester, the main constituent component is at least one structural unit selected from ethylene terephthalate, ethylene α, β-bis(2chlorophenoxy)ethane-4,4'-dicarboxylate, and ethylene 2,6-naphthalate units. This 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 layer B, which has thermoplastic resin B as its main component, but if the average particle size is 0.00
7-2 μm1 especially 0.02-1 μm particles 0.001
A content of up to 0.5% by weight, especially 0.005 to 0.3% by weight, and even 0.005 to 0.2% by weight is highly desirable because the scratch resistance becomes even better. As for the types of particles contained, it is desirable to use those preferably used for thermoplastic resin A. Thermoplastic resin A
(!: The types and sizes of particles contained in 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.

In the present invention, film layer A forms the non-magnetic surface. That is, when the biaxially oriented thermoplastic resin film is a single film, one surface of the film is a nonmagnetic surface and a magnetic layer is formed on the other surface. Further, in the case of a composite film of film layer A and film layer B, film layer A forms a non-magnetic surface, and film layer B is provided with a magnetic layer. In addition, in the case of a three-layer composite film of film layer A/film layer B/film layer A, one film layer A forms a non-magnetic surface,
The other film layer A is provided with a magnetic layer.

In the present invention, the height distribution standard deviation σ (n m ) of surface protrusions on a non-magnetic surface and the number N of protrusions exceeding 225 nm in height are calculated.
(pieces/mm2) is O≦(3(7-225)N<5X10
'Satisfy. Preferably 0≦(3σ-225)N<3
X10', more preferably 0≦(3σ-225)N
<1xlO'. If this value is too small, the scratch resistance will not be satisfied, and if this value is too large, the dubbing resistance will deteriorate.

The magnetic layer in the present invention is not particularly limited, but magnetic materials include γ-Fe2O3, Co-containing 7-Fe203
, CrO2, Fe-Co, Fe-Co-Ni, etc., into a binder made of polyvinyl chloride, polyvinyl acetate, polyurethane, nitrocellulose, etc., a copolymer or mixture thereof, or a binder made of these and other resins. Examples include magnetic paints obtained by dispersion. Furthermore, as a magnetic material, C
01Co--Cr and other metals may be deposited by vacuum deposition methods such as vacuum evaporation, sputtering, or ion blasting.

Next, a method for manufacturing the film used in the present invention will be explained.

First, as a method for incorporating particles into thermoplastic resin A, when the thermoplastic resin is polyester, it is dispersed in the form of a slurry of ethylene glycol, which is a diol component, and this ethylene glycol is polymerized with a predetermined dicarboxylic acid component. This is effective in obtaining a film that does not tear during stretching, has a relationship between thickness and average grain size, has a content within the range of the present invention, and has an orientation state within a desirable range. In addition, by adjusting the melt viscosity and copolymerization components of the polyester containing the particles,
The method of keeping the crystallization parameter ΔTcg in the range of 40 to 65°C does not cause stretching breakage, and the relationship between the thickness and average grain size within the range of the present invention, the content, the orientation state within the desired range, the surface layer particle concentration ratio, and the average protrusion height. Rt/Rp ratio, Rt/R
This is effective in obtaining a film with an a ratio.

In addition, a slurry of ethylene glycol of particles was added to
The method of heat treatment at a temperature of 200°C, especially 180 to 200°C for 30 minutes to 5 hours, especially 1 to 3 hours, does not cause stretching breakage, and the relationship between thickness and average grain size, content, and orientation state within the desired range of the present invention can be achieved. , is effective in obtaining a film with a surface layer particle concentration ratio.

In addition, as a method for incorporating particles into a thermoplastic resin, the particles are heat-treated in the same manner as above, and then mixed with the thermoplastic resin in the form of a slurry in which the solvent is replaced with water, using a vent-type twin-screw extrusion machine. The method of kneading and kneading into a thermoplastic resin also depends on the relationship between the thickness and average particle diameter within the range of the present invention, the content, the orientation state within the desired range, the surface layer particle concentration ratio, the average protrusion height,
It is extremely effective in obtaining films with Rt/Rp ratios and Rt/Ra ratios.

One way to adjust the particle content is to prepare a high-concentration master using the method described above, and then dilute it with a thermoplastic resin that does not substantially contain particles during film formation to adjust the particle content. It is valid.

After drying the pellets containing a predetermined amount of particles as necessary, the pellets are supplied to a known melt extruder, extruded into a sheet through a slit-shaped die at a temperature above the melting point of the thermoplastic resin and below the decomposition point, and then passed through a casting roll. The film is then cooled and solidified to form an unstretched film. In this case, when extruding into an unstretched film, the ratio of die slit gap/unstretched film thickness is set in the range of 5 to 30, preferably 8 to 20, and the voltage of the electrostatic casting method is set in the range of 5000 to 1500.
0V, preferably from 6000 to 2000V, the relationship between thickness and average grain size within the range of the present invention, content range, orientation state within a desirable range, surface layer particle concentration ratio, total reflection Raman crystal without stretching tearing. It is effective to obtain a film with a high chemical index.

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 0 to 6.5 times is effective for obtaining a film without tearing due to stretching and having the relationship between thickness and average grain size, content, orientation state and surface layer particle concentration ratio within the range of the present invention. However, when the thermoplastic resin is a molten optically anisotropic resin, the stretching ratio in the longitudinal direction is suitably 1 to 1.times.1.

The longitudinal stretching temperature varies depending on the type of thermoplastic resin, but it is usually 50 to 130 degrees at the first stage.
℃, and higher than that for the second and subsequent stages to obtain a film with the relationship between thickness and average particle size, content, orientation state within the desired range, average protrusion height, and surface layer particle concentration ratio within the range of the present invention. It is valid. Longitudinal stretching speed is 5000-50
A range of 000%/min is suitable. 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 1000-20000%/min, and the temperature is 80-2000%/min.
A range of 1600C is preferred. Next, this stretched film is heat treated. The heat treatment temperature in this case is 170-220
℃, especially 170-210℃, time is 0. A range of 5 to 60 seconds is suitable.

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

Predetermined thermoplastic resin A 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, as a method of controlling the lamination thickness, a method of controlling the temperature in the width direction of the merging block in accordance with the lamination thickness will prevent stretching tearing, and the relationship between the thickness and average grain size within the range of the present invention, the content, and the desired range. Orientation state, average protrusion height, Rt/Rp ratio, Rt/
This is effective in obtaining a film with a good Ra ratio and a surface layer particle concentration ratio.

In addition, the melting temperature of the extruder on the thermoplastic resin A side can be made higher by 10 to 40°C than on the thermoplastic resin B side.
No stretching tear, relationship between thickness and average grain size within the range of the present invention, content, orientation state within a desirable range, average protrusion height, Rt/
It is effective in obtaining a film with Rp ratio, Rt/Ra ratio, surface particle concentration ratio, and total reflection Raman crystallization index.

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 B. Furthermore, in the heat treatment process of the two-layer laminated film, the temperature of the hot air blown onto the thermoplastic resin A layer is 3 to 20°C lower than that of the thermoplastic resin B layer. , is effective in obtaining a film with desired range of orientation state, average protrusion height, Rt/Rp ratio, Rt/Ra ratio, surface layer particle concentration ratio, and total reflection Raman crystallization index.

A predetermined magnetic layer is applied to the biaxially oriented film thus obtained. The magnetic layer can be applied by a known method, but the drying process after application is performed at a temperature of 90 to 12
The temperature is preferably 0°C.

In addition, the calendering process uses polyamide or polyester as an elastic roll, and
C. is effective for obtaining a film having a relationship between thickness and average particle size within the range of the present invention and a surface layer particle concentration ratio within the desired range of the present invention. Further, after curing the magnetic layer of this film, the original (wide width) film is slit to obtain the high-density recording videotape of the present invention.

[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.

This is observed with a SEM (scanning electron microscope), and the image of the particles (shades of light produced by the particles) is connected to an image analyzer.The observation points are changed and the following numerical processing is performed when the number of particles is 5000 or more. The number average diameter thus determined is defined as the average particle diameter.

D-ΣD, /N Here, DI is the circular diameter of the particle, N is the number.

(2) 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 (% by weight) to the total weight of the particles is defined as the particle content. In some cases, infrared spectroscopy may also be effective.

(3) Crystallization parameter ΔT c g, heat of fusion DSC (
It was measured using a differential scanning calorimeter).

The DSC measurement conditions are as follows. That is, sample 1
0 mg was set in a DSC device, melted at a temperature of 300° C. for 5 minutes, and then rapidly cooled in liquid nitrogen.

This rapidly cooled sample was heated at a rate of 10°C/min, and the glass transition point T
g 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) is defined as a crystallization parameter ΔTcg.

(4) Surface molecular orientation (refractive index) 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 (NI 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 is measured using a Ramanor U-1000 Raman system manufactured by the company.
Polarization measurement ratio (YY/XX ratio, etc.) of the band intensity ratio of and 1730 cm-'' (stretching vibration of carbonyl group).

Here, use the fact that YY (man light detection parallel to Y with the polarization direction of the laser set to Y, Xx (man light detection parallel to X with the polarization direction of the laser set to X) corresponds to molecular orientation. can. 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. The measurement conditions in this case are as follows.

■Light source Argon ion laser (5145A) ■Setting the sample The surface of the film is pressed against a total reflection prism, and the incident angle of the laser to the prism (angle with the film thickness direction) is 60°.
°.

■Detector PM: RCA31034/Photon Coun
ting System (Ilamamafsu Cl
23 [1) (supply 16 (JOY) ■Measurement conditions 5LIT 1000μm LASER10
0mW GATE TIME 1.0secSCAN
5PEED 12c+N'/m1nS 8MPL
ING INTERVAL 0.2cmREPEA
T TIME 6 (5) Total reflection Raman crystallization index The total reflection Raman spectrum was measured in the same manner as in (4) above, and 1730 Cm-, which is the stretching vibration of the carbonyl group, was measured.
The half-width of the surface was taken as the total reflection Raman crystallization index of the surface.The measurement depth was about 500 to 1000 angstroms from the surface.

(6) Average height of surface projections 2-detector power type scanning electron microscope [ESM-3200,
manufactured by Elionix Co., Ltd.] and a cross-sectional measuring device [PMS-1,
Elionix Co., Ltd.], the height of the protrusion was scanned with the height of the flat surface of the non-magnetic tape as O. Carl Zeis (
The film is sent to Seiko Co., Ltd., and an image of the protrusions on the film surface is reconstructed on an image processing device. Next, the highest value among the individual protrusion parts obtained by binarizing the protrusion parts using this surface protrusion image 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 to determine the number of protrusions, and the average value of the heights of all the measured protrusions was taken as the average height. The standard deviation of the protrusion height distribution is the normal distribution function Ni = Aexp (-hi 2/2 (72) (however, h
i, Ni, and A are respectively defined as σ obtained by the least squares method from the protrusion height, the number of protrusions at height hi, and a constant.

Further, the magnification of the scanning electron microscope is selected to be between 1000 and 8000 times.

In some cases, a high-precision optical interference type three-dimensional surface analysis device (TOPO-3D manufactured by WYKO, objective lens: 40
~200 times, use of a high-resolution camera is effective) may be read as the above-mentioned SEM value and used.

(7) Centerline average surface roughness Ra, centerline depth Rp, maximum height Rt, protrusion spacing Sm Measured using a high-precision thin film step measuring instrument ET-10 manufactured by Koita Research Institute. The conditions were as follows, and the average value of 20 measurements was taken as the value.

・Stylus tip radius: 20.5 μm ・Stylus load: 5 mg ・Measurement length: 1 mm ・Cutoff value: 0.08 mm The definitions of Ra, Rp, and Rt ``Measurement and Evaluation Methods'' (Sogo Technological Center 1983).

(8) Young's modulus 2 using an Instron type tensile tester according to the method specified in J I 5-Z-1702.
Measurement was performed at 5° C. and 65% RH.

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

That is, ηsp/C”” [ηko +K [η] 2 ・ With a smile, η5. = (solution viscosity/solvent viscosity) -1, C is the weight of dissolved polymer per 100ml of solvent (g/100ml
, usually 1.2), K is the Huggins constant (assumed to be 0,343). In addition, solution viscosity and solvent viscosity were measured using an Ostwald viscometer.

(10) Surface layer particle concentration ratio Using secondary ion mass spectrometry (SIMS), the concentration ratio of the highest concentration element among the elements caused by particles in the film and the carbon element of the polyester is defined as the particle concentration,
Perform analysis in the thickness direction.

The ratio of the particle concentration A at the outermost layer particle concentration (point at depth 0) measured by SIMS to the maximum concentration B obtained by further analysis in the depth direction, A/B, was defined as the surface layer concentration ratio. The measuring device and conditions are as follows. The measuring device and conditions are as follows.

■ Measuring device Secondary ion mass spectrometer (SIMS) A-DIDA3000 manufactured by ATOMIKA, West Germany ■
Measurement conditions Primary ion species: 0□ Primary ion acceleration voltage: 12KV Primary ion current: 200nA Raster area: 400μm Mouth analysis area: Gate 30% Measurement vacuum degree: 6. OX 10-9 TorrE −
GUN: 0.5KV-3,0A (11) Single particle index A cross section of the film is photographed and observed using a transmission electron microscope (TEM) to detect particles. If the observation magnification is set to about 100,000 times, a single particle that cannot be separated any further can be observed. When the total area occupied by particles is A1 and the area occupied by aggregates in which two or more particles are aggregated is B, (A-B)/A is defined as a single particle index. T.E.
The M conditions are as follows: one field of view area: 2 μm2 is measured at different locations, and 500 fields of view are measured.

・Equipment 2 JEM-1200EX ・Observation magnification:
100,000 times Acceleration voltage: 100 kV Section thickness: Approximately 1000 angstroms (12) Particle size ratio Average value of the long diameter of each particle in the measurement of (1) above /
It is the ratio of the average value of the short axis.

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

Long axis=ΣD1. /N Short diameter=ΣD2. /N Di, ,D2. are the major axis (maximum diameter) and minor axis (shortest axis) of each individual particle, and N is the total number.

(13) Relative standard deviation of particle size Standard deviation σ(=f(Σ(
D, -D) 2/N+) divided by the average diameter (σ/
D).

(14) Thickness of thermoplastic resin A layer in laminated film Using a secondary ion mass spectrometer (SIMS), it was determined that the inner shell of particles in the film also contained a high concentration of elements originating from particles and carbon elements of polyester. The concentration ratio (M”/C+) is defined as the particle concentration, and analysis is performed in the depth (thickness) direction from the surface of the thermoplastic resin layer A.In the surface layer, the particle concentration is low due to the interface called the surface, and the particle concentration increases as the distance from the surface increases. The concentration increases.In the case of the film of the present invention, the particle concentration once reached the maximum value at depth [I] begins to decrease again.Based on this concentration distribution curve, the particle concentration becomes 1/2 of the maximum value. Depth [■]
(Here, II>I) was taken as the lamination thickness.

The conditions are the same as in measurement method (10).

Note that if the most abundant particles in the film are organic polymer particles, it is difficult to measure with SIMS, so instead of etching from the surface, XPS (X-ray photoelectron spectroscopy),
The depth profile of the particle concentration may be measured using IR (infrared spectroscopy) or a confocal microscope, and the layer thickness may be determined using the same method as described above.

Furthermore, the laminated thickness of the thermoplastic resin A may be determined not from the depth profile of the particle concentration described above, but by observing the cross section of the film, using a thin film step measuring device, or the like.

In addition, the thickness in the case of a single layer film can be determined by a known method such as a dial gauge method, an optical interference method, a gravimetric method, a thin film step measurement method, and the like.

(15) Using a scratch resistance tape running tester, run on a guide pin (surface roughness: Ra, 10100n (running speed 100).
0 m/min, number of runs: 10 passes, wrapping: m: 60°, running tension crab: 80 g). At this time, the scratches on the non-magnetic surface of the tape are observed under a microscope, and less than 2 scratches with a width of 2.5 μm or more per tape width are considered good, 2 or more and less than 10 scratches are considered good, and 10 or more scratches are considered poor. did. Excellent is desirable, but good is still usable for practical purposes.

(16) Using a household VTR on a dubbing-resistant tape, record a 100% chroma signal using a Shibaku TV test waveform generator (TG7/U706), and use the Shibaku color video noise measuring device (925D/U706) from the playback signal. The chroma S/N was measured in 1) and designated as A. In addition, the same sample tape (unrecorded) on which the master tape pancake with the same signal as above was measured using a magnetic field transfer type video software high-speed printing system (for example, Sony Magnescale's Sprinter). The chroma S/N of the tape after dubbing it onto pancakes was measured in the same manner as above, and it was designated as B. The chroma S/N reduction (A-B) due to this dubbing is 3 dB.
Dubbing resistance was determined to be excellent if it was less than 3 dB, good if it was 3 dB or more and less than 5 dB, and poor if it was 5 dB or more. Excellent is desirable, but good is still usable for practical purposes.

[Example code] The present invention will be explained based on examples.

Examples 1 to 4, Comparative Examples 1 to 4 Ethylene glycol slurry containing crosslinked polystyrene particles and silica particles derived from colloidal silica with different average particle sizes was prepared, and this ethylene glycol slurry was heat-treated at 190°C for 1.5 hours. After that, the particles were subjected to transesterification reaction with dimethyl terephthalate, followed by polycondensation, and the particles were reduced to 0.
Pellets of polyethylene terephthalate (hereinafter abbreviated as PET) containing 15 to 10% by weight were made. At this time, the polycondensation time was adjusted so that the intrinsic viscosity was 0.64 (thermoplastic resin A). In addition, by the usual method, the intrinsic viscosity was 0.62.
A substantially particle-free PET was produced and designated as thermoplastic resin B. These polymers were each heated at 180°C for 3
It was dried under reduced pressure (3 Torr) for an hour. Thermoplastic resin A is supplied to extruder 1 and melted at 288°C, thermoplastic resin B is further supplied to extruder 2 and melted at 285°C, and these polymers are merged and laminated in a merging block (feed block). Then, using an electrostatic casting method, the film was wound around a casting drum with a surface temperature of 30° C., and cooled and solidified to produce an unstretched film with a two-layer structure. At this time, an unstretched film was prepared with a ratio of die slit gap/unstretched film thickness of 10. Further, the total thickness and the thickness of the film layer A were adjusted by adjusting the discharge amount of each extruder. This unstretched film was stretched 4.0 times in the longitudinal direction at a temperature of 80°C. 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 4 times in the width direction at 100°C at a stretching rate of 2000%/min using a stenter, and then heat-treated at 200°C for 5 seconds under a constant length to give a total thickness of 9μ.
Thickness of m1 film layer A is 0. A biaxially oriented laminated film of 2 to 6 μm was obtained.

A magnetic paint was applied to this film using a gravure roll. The magnetic paint was prepared as follows.

・Fe 100 parts Average size Length = 0.3 μm Acicular ratio: 10/1 Coercive force 20000e ・Polyurethane resin 15 parts ・Vinyl chloride/vinyl acetate copolymer 5 parts Nitrocellulose resin 5 parts ・Aluminum oxide powder
3 parts Average particle size: 0.3 μm ・Carbon black 1 part ・Lecithin 2 parts ・Methyl ethyl ketone 100 parts ・Methyl isobutyl ketone 100 parts ・Toluene
100 parts stearic acid
After mixing and dispersing 2 parts of the above composition in a ball mill for 48 hours, 6 parts of a curing agent was added, the resulting kneaded product was filtered through a filter to prepare a magnetic coating solution, and a magnetic coating solution was prepared, which was coated on the 8 sides of the thermoplastic resin of the above film. Coated, oriented in a magnetic field, dried at 110°C,
Furthermore, a small test calender device (steel roll/nylon roll, 5 stages) was used at a temperature of 70℃ and a linear pressure of 200kg.
After calendering at 70° C./cm, curing was performed at 70° C. for 48 hours to obtain a high-density recording videotape.

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

[Effects of the Invention] The present invention utilizes a thermoplastic resin containing particles by devising a manufacturing method to improve the relationship between the particle size and film thickness, the content, the film thickness, and the height of the surface protrusions on the non-magnetic surface. The film or its laminated film has a specific range of the relationship between the standard deviation of the distribution and the number of protrusions, so scratch resistance,
We were able to create a videotape that has excellent dubbing resistance and can withstand high-density recording.

Claims (8)

[Claims] (1) Consisting of a biaxially oriented thermoplastic resin film having a film layer A forming a non-magnetic surface and a magnetic layer, the height distribution standard deviation σ (nm) of surface protrusions on the non-magnetic surface and protrusions exceeding 225 nm in height The number N (pieces/mm^2) is 0≦
(3σ-225)N<5×10^4, the film layer A is mainly composed of thermoplastic resin A and particles and has a thickness of 0.005 to 3 μm; The average particle diameter of the particles contained in A is 0.1 to 10 times the thickness of the film layer A, and the content of the particles is 0.5 to 50
% by weight of high-density recording videotape. (2) The biaxially oriented thermoplastic resin film has film layer A
2. The high-density recording videotape according to claim 1, wherein the videotape is a composite film comprising a film layer B containing a thermoplastic resin B as a main component, and a film layer B containing a thermoplastic resin B as a main component. (3) The biaxially oriented thermoplastic resin film has film layer A
2. A composite film comprising a film layer B and a film layer A, wherein one film layer A forms a non-magnetic surface and the other film layer A forms a magnetic layer. High-density recording videotape. (4) The videotape for high-density recording according to claim 2 or 3, wherein the film layer B contains substantially no particles. (5) Film layer B is composed of thermoplastic resin B and an average particle size of 0.
4. The high-density recording videotape according to claim 2, wherein the main component is particles having a diameter of 0.007 to 2 .mu.m, and the content of the particles is 0.001 to 0.5% by weight. (6) Thermoplastic resin A is crystalline polyester, and the total reflection Raman crystallization index of the surface of film layer A is 2.
Claim 1~ characterized in that it is 0 cm^-^1 or less.
5. The high-density recording videotape according to any one of 5. (7) The particles contained in film layer A have a particle size ratio of 1.0
7. A high-density recording videotape according to any one of claims 1 to 6, characterized in that the grain size is ~1.3. (8) The videotape for high-density recording according to any one of claims 1 to 7, wherein the relative standard deviation of the particles contained in the film layer A is 0.6 or less.