JPH03209618A - Supporting body for ferromagnetic metallic thin film - Google Patents

Abstract

PURPOSE:To obtain the ferromagnetic metallic thin film supporting body excellent in an electromagnetic conversion characteristic and a handling characteristic by specifying the range of the average height of projections formed on a face which does not come into contact with the ferromagnetic metal of a biaxial orientation film. CONSTITUTION:The ferromagnetic metallic thin film supporting body is the biaxial orientation film consisting of thermoplastic resin and inactive grains A contained in the resin as main components. Surface projections consisting of the grains A contained in the resin as nucleuses are formed on the face not contacted with the thin film, i.e. a traveling face. The average height of the surface projections is 1/4 or more the average grain size of the grains A. The preferable value of the average height is >=1/3.5 and the more preferable value is >=1/3. The average height <1/4 is not preferable because a film having both the output and handling characteristics can not be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a support for a ferromagnetic metal thin film.

Specifically, the present invention relates to a support for a ferromagnetic metal thin film that has good handling characteristics when a ferromagnetic metal thin film is formed on the support and used as a high-density magnetic recording medium.

[Prior Art] A support for a ferromagnetic metal thin film, on which a ferromagnetic metal thin film is formed by a method such as vacuum deposition, is mainly used as a high-density magnetic recording medium. In this case, the functions required of the support are not just mechanical properties to support the magnetic layer, but also desirable electromagnetic conversion properties to smoothly support the extremely thin magnetic layer, as in the case of coated high-density magnetic recording media. There has been a demand for a surface shape that imparts this, and for the support itself to have good handling characteristics, that is, to be easy to slip.

Conventionally, biaxially oriented polyester films have been mainly used as materials for supports for high-density magnetic recording media.
In order to meet the above requirements, attempts were made to specialize the front and back sides of the film (Japanese Patent Laid-Open No. 49-74910,
JP-A-51-149006, JP-A-52-842
Publication No. 64).

In other words, in order to achieve good electromagnetic conversion characteristics, the surface of the film in contact with the ferromagnetic metal (hereinafter referred to as the magnetic surface) is formed to be smooth, and the opposite surface (hereinafter referred to as the running surface) is made rough and easy to smooth. This ensures good handling characteristics.

This technology has allowed development to proceed by separating the functions of the support into the magnetic surface and running surface. The magnetic surface is not only smooth, but also has a film with granular or earthworm-like protrusions on the surface to improve the held touch, abrasion resistance, and durability of the ferromagnetic metal thin film (Japanese Unexamined Patent Publication No. 1983-1999). 1693
No. 7, JP-A No. 58-68223, etc.), and methods that have a head cleaning effect due to surface ridges based on polymerization catalyst residues and added fine particles in the film (JP-A No. 58-68225, etc.). ), and those in which fine particles are present in the film to improve durability under high temperature and high humidity conditions (JP-A-59-84927, etc.). However, when it comes to the running surface, it is not enough to simply make it as rough and smooth as possible, but there is a restriction that it must not be transferred to the ferromagnetic metal thin film on the magnetic surface during winding, impairing its smoothness and fine shape. There was an upper limit to the surface roughness, and it was necessary to combine it with an easily slippery film (Japanese Patent Laid-Open Publication No. 153639/1983, etc.).

[Problems to be Solved by the Invention] Recently, metal thin film magnetic recording media have made remarkable progress, and high-quality vapor-deposited video tapes that take advantage of their suitability for high-density recording have come on the market for consumer use. With the industrialization of vapor deposition tapes, demands for improved handling characteristics of supports for ferromagnetic metal thin films have become increasingly severe.

However, with the conventional technology, there is a limit to the improvement of the running surface due to the above-mentioned transfer limitations, and the handling characteristics have also reached their limits. If the handling characteristics are improved by making the running surface smoother, the surface shape will be transferred to the ferromagnetic metal thin film that is the magnetic layer, deteriorating the electromagnetic conversion characteristics.

The purpose of the present invention is to solve these problems and provide a support for a ferromagnetic metal thin film that has extremely excellent electromagnetic conversion characteristics when made into a ferromagnetic metal thin film type magnetic recording medium, and at the same time has excellent handling characteristics. do.

[Means for Solving the Problems] The present invention provides: (1) A biaxially oriented film whose main components are a thermoplastic resin and inert particles contained in the resin, which does not come into contact with a ferromagnetic metal thin film. On the surface, surface protrusions are formed with the inert particles (A) contained in the resin as the core, and the average height of the surface protrusions is 1 of the average particle diameter of the inert particles (A). 2. A support for a ferromagnetic metal thin film, characterized in that: The gist of the invention is a support for a ferromagnetic metal thin film on which a film is formed.

The thermoplastic resin constituting the present invention is not particularly limited, but
Crystalline thermoplastic resins such as polyester, polyolefin, polyamide, and polyphenylene sulfide are preferably used, among which polyester and polyphenylene sulfide, particularly polyester, are preferably used. Also, among polyesters, ethylene terephthalate, ethylene α, β-bis(
In order to obtain the surface morphology within the scope of the present invention, the main constituent is at least one structural unit selected from 2-chlorophenoxy)ethane-4,4'-dicarboxylate and ethylene 2,6-naphthalate units. desirable. Here-
Crystallinity means that it is not so-called amorphous, and quantitatively the melting point is detected by thermal analysis using a differential scanning calorimeter (DSC) at a heating rate of 10°C/min. Preferably the crystallization parameter ΔTcg is 150°C
These are as follows.

The inert particles constituting the present invention are not particularly limited, but include:
Spherical particles having a particle size ratio (longer axis/breadth axis of particles) of 16° to 1.3 are preferable because the surface morphology within the range of the present invention can be easily obtained.

The inert particles constituting the present invention are not particularly limited, but include:
The relative standard deviation of particle size distribution is 0.6 or less, preferably 0.
．． When it is 5 or less, it is preferable because a surface morphology within the range of the present invention can be easily obtained.

Types of inert particles that satisfy the above desirable characteristics include substantially spherical silica particles derived from colloidal silica, particles made of crosslinked polymers (for example, crosslinked polystyrene), but are not limited to these. Rather, it is possible to use other particles such as titanium dioxide, alumina, and calcium carbonate by devising a film-forming method.

The size of the inert particles (A) is not particularly limited, but the average particle size (diameter) is 5 to 2000 nm, particularly 10 to 1500 nm.
nm, and more preferably from 10 to 300 nm, because the friction coefficient and output characteristics are even better.

The total content of inert particles (A) and (B) in the present invention is not particularly limited, but the content of the entire film is 0.000
A content of 5 to 0.5% by weight, preferably 0°001 to 0.3% by weight, and more preferably 0.001 to 0.15% by weight is particularly desirable because handling characteristics and output characteristics are even better. .

The support of the present invention has a composition consisting of the above-mentioned thermoplastic resin and inert particles as a main component, 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. Moreover, a slippery film, a non-smooth film, or a film containing fine particles may be formed on the surface. Further, organic particles may be closely attached to the magnetic surface side to form protrusions.

The materials for these films and organic particles are not particularly limited, but materials known in the fields of magnetic recording and metal corrosion protection can be used. The method of forming the material is not particularly limited, but it is desirable to dilute the material with water or a solvent, apply it, and dry it.

The support of the present invention is a biaxially oriented film of the above composition. - An axially or non-oriented film is not preferable because its handling properties 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 200 kg/mm in both the longitudinal direction and the width direction.
When it is 2 or more, handling characteristics become even better, so it is extremely desirable. Although the upper limit of Young's modulus, which is a measure of the degree of molecular orientation, varies depending on the type of thermoplastic resin and cannot be defined as one type, the manufacturing limit is usually about 5000 kg/mm 2 .

Measured by Atsube refractometer, laser refractometer, total internal reflection laser Raman method, etc., from the surface of the running surface of the present invention excluding the coating to a depth of 1 μm (if the film thickness is 1 μm or less, It is particularly desirable when the molecular orientation (up to the opposite surface) is biaxial because the output characteristics and handling characteristics become even better. Furthermore, it is particularly desirable if the thermoplastic resin in this portion is crystalline, since handling characteristics and output characteristics will be even better.

In the support of the present invention, the average height of the surface protrusions on the surface excluding the coating from the running surface is preferably 1/4 or more of the average particle size (diameter) of the inert particles (A) forming the core of the protrusions. 1/3.5
Above, it is more preferable that it is 1/3 or more. If the average protrusion height on the running surface is less than 1/4 of the average particle diameter, it is not preferable because a film that achieves both output characteristics and handling characteristics cannot be obtained. The upper limit of the average protrusion height is not particularly limited, but the manufacturing limit is about 1.5 to 2 times the average grain size.

The height of the surface projections on the running surface of the support of the present invention excluding the film is not particularly limited, but the average height is 3 to 500n.
m, particularly from 10 to 250 nm, is particularly desirable since the output characteristics when made into a magnetic tape and the rolling characteristics of the film are even better.

The density of protrusions on the running surface of the support of the present invention excluding the film is not particularly limited, but if the total number of protrusions on the surface satisfying the surface morphology of claim 1 is N (number/mm2), The content Φ (wt%) of the inert particles (A) and the average particle diameter D (nm) of the particles are expressed by the following formula (1), preferably (2)
, and more preferably, when (3) is satisfied, it is particularly desirable because the output characteristics and handling characteristics of the film when made into a magnetic tape are even better.

N/(Φ/D)≧5×1013...(1)N
/(Φ/D)≧7×1013...(2)N/
(Φ/D)≧10×1013 (3) The support of the present invention has a ratio of the center line average roughness Ra of the surface excluding the coating from the running surface to the maximum height Rt, Rt/Ra of 8 .5
Below, it is particularly preferable to use a value of 8.0 or less because the handling characteristics and output characteristics become even better.

As mentioned above, it is desirable that the thermoplastic resin constituting the support of the present invention is crystalline, but in particular, the surface layer excluding the coating, especially the running surface from the surface excluding the coating, to a depth of 1
The crystallization parameter ΔTcg of the μm polymer is 10 to 10
A temperature of 0° C. is particularly desirable because the handling characteristics become even better.

The support of the present invention is particularly desirable when the centerline average roughness Ra of the surface excluding the coating from the running surface is 1 to 1100n, since the handling characteristics and output characteristics will be even better.

The support of the present invention has a relative standard deviation (standard deviation of height distribution/average height) of surface protrusions on the surface excluding the coating from the running surface.
The support of the present invention is particularly preferable because the handling characteristics and output characteristics are even better when it is 0.5 or less, particularly 0.4 or less, and even 0.35 or less. The surface layer particle concentration ratio measured by secondary ion mass spectrum is 1/10 or less, especially 1150
It is particularly desirable that the following is the case, since the handling characteristics and output characteristics will be even better.

Next, a method for manufacturing the support of the present invention will be explained.

First, the inert particles (A) can be incorporated into the thermoplastic resin either after, during, or before polymerization, but the most common method is to knead them into the polymer using a vent-type twin-screw presser. This is effective in obtaining a film having a surface morphology within the range of the invention. In addition, as a method of adjusting the content of inert particles (A), a high concentration master is made by the above method,
A method in which the particle content is adjusted by diluting it with a thermoplastic resin that does not substantially contain inert particles during film formation is effective for obtaining a film having the surface morphology of the present invention. Furthermore, the melt viscosity of this inert particle (A) high concentration master polymer,
By adjusting copolymerization components etc., its crystallization parameter ΔT
A method in which the cg is kept in the range of 30 to 80°C is effective in obtaining a film without stretching tearing and having a surface morphology within the range of the present invention.

After thoroughly drying the pellet A containing the inert particles (A), it is supplied to a known melt extruder and melted at a temperature above the melting point and below the decomposition point of the thermoplastic resin, and then the other 1.50 n Thermoplastic resin B containing inert particles (B) of 1.0 m or less, or thermoplastic resin C containing substantially no inert particles, is supplied to a known lamination device and extruded into a sheet from a slit-shaped die. The film is then cooled and solidified on a casting roll to form an unstretched film. That is, these thermoplastic resins are laminated using two or three extruders, a merging block for two or three layers, or a die. When using the confluence block method, the laminated portion is rectangular, and the difference in melt viscosity of the two thermoplastic resins (
absolute value) from 0 to 2000 poise, preferably from O to 100
Keeping the voids within the range of 0 is effective for industrially producing a film having a surface morphology within the scope of the present invention stably and without unevenness in the width direction.

In addition, in the state of an unstretched film, the ratio of the thickness t of the thermoplastic resin layer containing the inert particles (A) to the average particle size (diameter) D of the included inert particles, t/D, is 24 or less. , preferably 12 or less, more preferably 8.5 or less, is extremely effective for producing a film having a surface morphology within the range of the present invention.

The above is for the case where the laminated structure is A/B, A/C, A/C/B, but of course, a multilayer structure with more than that is also possible (here, the type of thermoplastic resin for each of A, B, and C is the same). However, it can also be a different species). The surface A is the running surface of the present invention.

Next, this multilayer unstretched film is biaxially stretched and biaxially oriented. The biaxial stretching method may be either a simultaneous biaxial stretching method or a sequential biaxial stretching method, but in the case of a sequential biaxial stretching method in which the film is stretched in the longitudinal direction and then in the width direction, the film having the surface morphology within the range of the present invention can be stabilized. Therefore, it is effective for industrial production without unevenness in the width direction. In the case of sequential biaxial stretching, the stretching in the longitudinal direction is divided into three stages, especially four or more stages, and the stretching is performed at 40 to 150°.
C and a stretching speed of 1,000 to 50,000%/min for 3 to 6 times is effective for obtaining a film having a surface morphology within the range of the present invention. The stretching temperature and speed in the width direction are 80 to 170°C, 1000 to 2000
A range of 0%/min is preferred. The stretching ratio is preferably 3 to 10 times. Further, if necessary, it can be further stretched in at least one of the longitudinal direction and the width direction. In any case, the key point of the present invention is to provide an extremely thin layer containing inert particles and then stretch the film to an areal stretching ratio (lengthwise magnification x widthwise magnification) of 9 times or more. Next, this stretched film is heat treated. In this case, the heat treatment conditions are 140 to 280 °C, preferably 160 to 2
The temperature is preferably 20° C. for 0.5 to 60 seconds, but it is preferable to use microwave heating in combination with the heat treatment, as this makes it easier to obtain a film having a surface morphology within the range of the present invention. If a film is to be formed on the surface of the film if necessary, a known coating step is performed immediately before the transverse stretching step or immediately before the heat treatment step to apply the material, which eliminates the need for a special drying step.

In addition, in the state of the product film, the thickness t of the thermoplastic resin layer containing the inert particles (A) and the thickness t of the thermoplastic resin layer containing the inert particles (A)
) to the average particle size (diameter) D, t/D is 2 or less, preferably 1 or less, and more preferably 1 to 0.7 or less to produce a film having a surface morphology within the range of the present invention. It is extremely effective. Therefore, although the appropriate lamination thickness varies depending on the size of the inert particles (A) used and cannot be generalized, it is usually 5 to 100 nm, preferably 10 to 500 nm, to obtain the surface morphology within the range of the present invention. It is particularly effective because it is easy.

A feature of the process according to the invention is the biaxial stretching of the film after the application of a very thin layer containing inert particles (A) using a specially prepared highly concentrated particle polymer.

[Function] The present invention involves laminating a thermoplastic resin containing inert particles (A) with a high concentration master polymer under special conditions, and then biaxially stretching (1). Since the film had a running surface, it is presumed that the effects of the present invention were obtained as a result of the dramatic improvement in the protrusion characteristics of the surface.

[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 A thermoplastic resin is removed from the running surface side of a support for a ferromagnetic metal thin film using a plasma low-temperature ashing method (for example, Yamato Scientific PR-
503) to expose the particles. The processing conditions are selected so that the film and thermoplastic resin are incinerated, but the particles are not damaged.

This is observed with a SEM (scanning electron microscope), and an image of the particles (shades of light created by the particles) is analyzed using an image analyzer (for example, a QTM manufactured by Cambridge Instruments).
900) and changed the observation point to obtain a particle number of 1.00.
00 or more, perform the following numerical processing, and use the number average diameter obtained thereby as the average particle diameter.

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

If there is a film containing inert particles on the running surface of the support for ferromagnetic metal thin film, either remove this film in advance and then perform ashing, or SEM images before ashing and SEM after ashing.
The particle size distribution is determined from the images and compared, and the influence of inert particles in the film is eliminated through numerical processing. This is not necessary in the case of inert particles of the same particle size.

(2) Particle content Select a solvent that dissolves the thermoplastic resin but does not dissolve the inert particles, centrifuge the particles from the thermoplastic resin, and determine the particle content as the ratio (wt%) to the total weight of the particles. . In some cases, infrared spectroscopy may also be effective.

If there is a film containing an insoluble substance on the surface of the support for a ferromagnetic metal thin film, this film is removed in advance before dissolution.

(3) Glass transition point Tg, cold crystallization temperature Tcc.

Crystallization parameter ΔTcg and melting point were measured using a PerkinElmer DSC (differential scanning calorimeter) type II. The DSC measurement conditions are as follows. That is, 10 mg of sample was set in the DSC device, and 3
After melting for 5 minutes at a temperature of 00°C, it is quenched into liquid nitrogen. This rapidly cooled sample is heated at a rate of 10° C./min, and the glass transition point Tg is detected. The temperature was further increased, and the exothermic peak temperature of crystallization from the glass state was defined as the cold crystallization temperature Tcc. The temperature was further increased, and the melting peak temperature was taken as the melting point. Further, the difference between Tcc and Tg (Tcc - Tg) is defined as a crystallization parameter ΔTcg.

(4) Surface molecular orientation (refractive index) Measure the running surface of the support for ferromagnetic metal thin film.

If there is a film on this surface, remove this film before starting the measurement.

Measurement was performed 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 165%RH. The biaxial orientation of the polymer is such that when the refractive index in the longitudinal direction, width direction, and thickness direction is Nl, N2, and N3, the absolute value of (Nl - N2) is 0.07 or less, and N3 / [(Nl +
One criterion can be that 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, a total internal reflection laser Raman method can also be used.

Racer total internal reflection Raman measurement is performed by Jobin-Yvon
The total reflection Raman spectrum was measured using a Ramanor U-1000 Raman system manufactured by
In the case of , the polarization measurement ratio (YY/XX ratio, etc.) of the band intensity ratio of 1615 cm' (skeletal vibration of benzene ring) and 1730 cm' (stretching vibration of carbonyl group).

Here, YY: detection of Mann light parallel to Y with the polarization direction of the laser set to Y; XX: detection of Mann light parallel to X with the polarization direction of the laser set to X) corresponds to molecular orientation. Available. 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 6
It was set to 0'.

■Detector PM: RCA31034/Photon Coun
ting System (Hamanalsu C12
30) (supply 1600V) ■Measurement conditions 5LIT ] 000μm LASER10
0mW GATE TIME 1.0secS
CAN 5PEED 12cn+-1/min
SAMPLING INTERVAL O, 2cm'
REPEAT TIME 6 (5) Average height of surface projections Measure the running surface of the support for ferromagnetic metal thin film.

If there is a film on this surface, remove this film before starting the measurement.

Two-detector scanning electron microscope [ESM-3200,
manufactured by Elionix Co., Ltd.] and a cross-sectional measuring device [PMS-1,
The measured height of the protrusions was measured using an image processing device [I BA82000, Carl Zeiss Co., Ltd.] when the height of the flat surface of the film was set as 0.
[Manufacturer] and reconstructs the image of the film surface protrusions on an image processing device. Next, a circular equivalent diameter is determined from the area of each protrusion obtained by binarizing the protrusion portion using this surface protrusion image, and this is taken as the average diameter of the protrusion. Furthermore, the highest value among the binarized individual protrusion portions is determined as the height of the protrusion, and this value is determined for each protrusion. This measurement was repeated 500 times at different locations to determine the number of protrusions, and the average value of the heights of all the measured protrusions was taken as the average height. Furthermore, the standard deviation of the height distribution was determined based on the height data of each protrusion. Furthermore, the magnification of a scanning electron microscope is 1000~
Select a value between 8000 times. In some cases, a high-precision optical interferometric three-dimensional surface analysis device (WYKO T
The above S
It may be used by replacing it with the value of EM.

(6) Center line average surface roughness Ra and maximum height Rt of the running surface of the support for ferromagnetic metal thin film are measured.

If there is a film on this surface, remove this film before starting the measurement.

The measurement was performed using a high-precision thin film step measuring device 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: 0.5μm ・Stylus load: 5mg ・Measurement length: 1mm ・Cutoff value: 0.08mm The definitions of Ra and Rt can be found, for example, in 1 Surface Roughness Measurement by Jibu Nara. Evaluation Method” (General Technology Center 198
3).

(7) 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.

(8) Melt viscosity Temperature: 290'C using Koka flow tester.

Measurements were made at a shear rate of 200 cm-1.

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

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

Major axis = ΣDli/N Minor axis - ΣD2i/N Dli, Dji are the major axis (maximum diameter) and minor axis (shortest axis) of each individual particle, and N is the total number.

(10) Relative standard deviation of particle diameter The individual particle diameter Di1 average mean diameter 0 error σ (=f(Σ(Di −D) 2/N)) measured by the method in (1) above is calculated as the average diameter. It is expressed as the value divided by (σ/D).

(11) Surface concentration ratio Measure the running surface side of the support for ferromagnetic metal thin film.

Using a secondary ion mass spectrometer (SIMS), the particle concentration is determined as the concentration ratio of the element with the highest concentration among the elements caused by particles in the film and the carbon element of the polyester, and analysis is performed 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. If there is a film on the surface to be measured, the film is removed beforehand before measurement, or if the interface between the film and the film can be detected by STMS, the interface is set as the zero depth point described above. 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 Analysis area: Gate 30% Measurement vacuum degree: 6. 0XIO”TartE-GUN
: 0.5 kV-3, OA Note that in the case of particles that are difficult to measure by SIMS, total reflection infrared spectroscopy, confocal microscopy, etc. are also effective in measuring the depth profile of the particles.

(12) Using a tape runnability tester model TBT-300 (manufactured by Yokohama System Research Co., Ltd.), a film with a friction coefficient μ of 1 layer and 2 inch wide tape was prepared at 20°C, 160% RH. The vehicle was run in an atmosphere, and the initial coefficient of friction was determined using the following formula (
The film width was 2 inches per layer).

μ = 0.733 l og (T2 /Tl) where TI is the inlet tension and T2 is the outlet tension.

The guide diameter is 6mmφ, and the guide material is 5US27 (
The surface viscosity is 0.23), the winding angle is 180°, and the running speed is 3.3 cm/sec. μk obtained by this measurement
Or 0. If the friction coefficient was 3 or less, the friction coefficient was determined to be good, and if it exceeded 0.3, the friction coefficient was determined to be poor. This μ is the critical point that affects the handling characteristics when processing the film into magnetic recording media, capacitors, packaging, etc.

(13) Handling characteristics The produced support for a ferromagnetic metal thin film was slit into a 500 mm width x 5000 m length using a plastic core with an inner diameter of 6 inches so that the running surface was on the inside, and then rolled up into a roll. Ten rolls thus prepared are slit, and the number of rolls that can be wound well without wrinkles is counted and displayed. If more than 5 out of 10 rolls cannot be wound properly,
It is determined that the handling characteristics are poor.

(14) Output characteristics By continuous vacuum oblique evaporation method, Co,
Ni ferromagnetic metal thin film (Ni = 20% by weight, film thickness 150n
m) is formed in the presence of trace amounts of oxygen. The oxygen concentration is such that the oxygen content in the ferromagnetic metal thin film is 5 in terms of the atomic ratio to the metal.
%. Thereafter, stearic acid is applied to the surface of the obtained ferromagnetic metal thin film at a concentration of about 10 mg/rrf, and the film is slit into a width of 8 mm to obtain a magnetic tape. A 50 m length of this tape was assembled into a 5ONY High Eight cassette to make a VTR cassette tape.

Konotape im S ON Y home use VTR (EVS
900) was used to record a 100% chroma signal using a Shibaku TV test waveform generator (TG7/U706), and measure the chroma S/N from the playback signal using a Shibaku color video noise measuring device (925D/1). did.

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

Examples 1 to 4, Comparative Examples 1 to 2 Aqueous sol containing silica particles (particle concentration = 50%) caused by colloidal silica with different average particle sizes were converted into polyethylene terephthalate using a vented twin-screw extruder, respectively. By kneading a predetermined amount, a high concentration master pellet of 30w% was made. This master pellet and polyethylene terephthalate pellets containing substantially no inert particles were mixed at a predetermined ratio. 18 of these mixed pellets A
After drying under reduced pressure at 000 for 3 hours (5 Torr),
It was fed to extruder 1. On the other hand, polyethylene terephthalate pellets C containing substantially no inert particles were similarly dried and then fed to extruder 2 at 300°C.
After melting, the molten state is laminated into two layers using a rectangular feed block (A/C), extruded into a sheet form from a slit in the mouthpiece, and the surface temperature is set to 3 using an electrostatic casting method.
It was wound around a casting drum at 0° C. and cooled and solidified to produce an unstretched film with a two-layer structure. At this time, the discharge rate of the extruder was adjusted to change the ratio of the average particle diameter of the inert particles to the thickness t on one side of layer A, t/D. This unstretched film was stretched 3.3 times in the longitudinal direction at a temperature of 80°C. This stretching was carried out in three stages using different peripheral speeds between two sets of rolls.

This -axially stretched film was heated and dried at 100°C using a stick, and stretched at a stretching rate of 2000%/min to a width of 3.4 mm in the width direction.
Stretched twice. This film was heated to 200°C for 5 minutes under a fixed length.
A biaxially oriented polyester film having a total thickness of 10 μm was obtained by heat treatment for seconds. On the A side (running surface) of these films, there were many surface protrusions based on the silica particles kneaded into the A layer, and on the opposite side (magnetic side) there were no protrusions. The parameters of the present invention for these films are as shown in Table 1, and when the parameters were within the parameter range of the present invention, the handling characteristics and output characteristics were extremely good as shown in Table 1, but when they were not. In this case, a film satisfying both handling characteristics and output characteristics could not be obtained.

Comparative Example 3 Polyethylene terephthalate containing 2% by weight of silica particles with an average particle size of 150 nm was dried in the same manner as in Example 1, then melted at 300°C and extruded in a single layer, and the surface temperature was adjusted using an electrostatic casting method. It was wound around a casting drum at 30°C and cooled and solidified to produce an unstretched film with a single layer structure.

This unstretched film was stretched and heat treated in the same manner as in Example 1 to obtain a biaxially oriented polyester film with a thickness of 10 μm. There were many surface protrusions on both sides of this film based on the silica particles contained inside. As shown in Table 1, the properties of this film were outside the scope of the present invention; the handling properties were good, but the output properties were poor.

Example 5 A water dispersion coating liquid with the following formulation was applied to the outer surface of layer A of a uniaxially stretched film uniaxially stretched in the longitudinal direction for 8 m using a Meyer bar coater.
After applying the film at a rate of 1/m, it was laterally stretched using a stick. Otherwise, a biaxially oriented polyester film having a thickness of 10 μm was obtained in the same manner as in Example 1.

The A side (running surface) of these films has many surface protrusions based on the silica particles kneaded into the A layer, and the worm structure containing the silica particles added to the coating liquid can be easily formed on the surface. A slippery film was formed. Furthermore, no protrusions were present on the opposite surface (magnetic surface). The characteristics of this film are as shown in Table 1, and it was within the scope of the present invention and at the same time had high handling characteristics and output characteristics.

(Formulation) Water-soluble polyester methylcellulose colloidal silica (particle size 30 nm) Example 6 A water-dispersed coating liquid with the following formulation was applied to the outer surface of layer C of a uniaxially stretched film uniaxially stretched in the longitudinal direction using a Meyer bar coater.
After applying ml/rd, it was stretched laterally using a stick. Otherwise, a biaxially oriented polyester film having a thickness of 10 μm was obtained in the same manner as in Example 1.

The A side (running surface) of these films has many surface protrusions based on silica particles kneaded into the A layer, and the opposite side (magnetic side) has 0.3% by weight of A added to the coating liquid. 0.2% by weight 0.03% by weight Grill particles were closely attached to form protrusions. The characteristics of this film are as shown in Table 1, and it was within the scope of the present invention and at the same time had high handling characteristics and output characteristics.

(Formulation) Acrylic acid emulsion 0.2% by weight Methyl cellulose 0.05% by weight Example 7 A water-dispersed coating liquid with the following formulation was applied to the outer surface of layer C of a uniaxially stretched film uniaxially stretched in the longitudinal direction using a Meyer bar coater. 6m
After applying the film at a rate of 1/m, it was laterally stretched using a stick. Otherwise, a biaxially oriented polyester film having a thickness of 10 μm was obtained in the same manner as in Example 1.

On the A side (running surface) of these films, there were many surface protrusions based on the silica particles kneaded into the A layer, and on the opposite side (magnetic side), a film having a wormlike structure was formed. The properties of this film are as shown in Table 1, and are within the scope of the present invention, as well as having high handling properties.
It had output characteristics.

(Formulation) Methyl cellulose 0.15% by weight Example 8 A water-dispersed coating liquid with the following formulation was applied to the outer surface of layer C of a uniaxially stretched film uniaxially stretched in the longitudinal direction for 6 m using a Meyer bar coater.
l/n (After coating, it was laterally stretched using a stenter.Otherwise, it was carried out in the same manner as in Example 1 to obtain a biaxially oriented polyester film with a thickness of 10 μm.

The A side (running surface) of these films has many surface protrusions based on silica particles kneaded into the A layer, and the opposite side (magnetic side) has an earthworm structure containing silica particles added to the coating liquid. A film with a coating was formed. The characteristics of this film are as shown in Table 1, and it was within the scope of the present invention and at the same time had high handling characteristics and output characteristics.

(Formulation) Water-soluble polyester 0. 3% by weight Methyl cellulose 011% by weight Colloidal silica 0.03% by weight (particle size 20 nm
) Example 9 In Example 1, instead of polyethylene terephthalate C containing substantially no inert particles, an average particle size of 11
A biaxially oriented polyester film having a thickness of 10 μm was obtained in the same manner as in Example 1, except that polyethylene terephthalate B containing 0.05% by weight of 00n silica particles (B) was used. On the A side (running surface) of these films, there are many surface protrusions based on the silica particles incorporated in the A layer, and on the opposite side (magnetic side), there are about 1,000 protrusions based on the silica particles contained in the B layer. 20,000 pieces/m2 were formed.

The characteristics of this film are as shown in Table 1, and it was within the scope of the present invention and at the same time had high handling characteristics and output characteristics.

Example 10 A water dispersion coating liquid with the following formulation was applied to the outer surface of layer B of a uniaxially stretched film uniaxially stretched in the longitudinal direction for 6 m using a Meyer bar coater.
A biaxially oriented polyester film having a thickness of 10 μm was obtained in the same manner as in Example 9, except that after coating, the film was laterally stretched using a stenter.

On the A side (running surface) of these films, there are many surface protrusions based on the silica particles incorporated in the A layer, and on the opposite side (magnetic side), there are about 1,000 protrusions based on the silica particles contained in the B layer. 20,000 pieces/mm2 were formed, and a film having a wormlike structure was formed thereon.

The characteristics of this film are as shown in Table 1, and it was within the scope of the present invention and at the same time had high handling characteristics and output characteristics.

(Formulation) Methyl cellulose 0.15% by weight Example 11 A water-dispersed coating liquid with the following formulation was applied to the outer surface of layer B of a uniaxially stretched film uniaxially stretched in the longitudinal direction for 6 m using a Meyer bar coater.
l/rr? After coating, a biaxially oriented polyester film having a thickness of 10 μm was obtained in the same manner as in Example 9, except that it was laterally stretched using a stenter.

On the A side (running surface) of these films, there are many surface protrusions based on the silica particles incorporated in the A layer, and on the opposite side (magnetic side), there are about 1,000 protrusions based on the silica particles contained in the B layer. 20,000 particles/mm2 were formed, and a film having a worm-like structure containing silica particles contained in the coating solution was formed thereon. The characteristics of this film are as shown in Table 1, and it was within the scope of the present invention and at the same time had high handling characteristics and output characteristics.

(Formulation) Water-soluble polyester methylcellulose colloidal silica (particle size 20 nm) 0.3% by weight 0.1% by weight 0.03% by weight Since we created a film with a surface morphology, we have obtained a film that can achieve both handling characteristics and output characteristics at an extremely high level when used in ferromagnetic metal thin film magnetic recording media with this surface as the running surface. It is useful for improving the image quality of ferromagnetic metal thin film video tapes. In addition, this unique surface makes the film excellent in abrasion resistance and can withstand severe use, making it suitable for increasing film processing speeds in various applications. Applications of the film of the present invention are not particularly limited, but in addition to the above-mentioned magnetic recording media, it can also be used for packaging that takes advantage of the handling characteristics related to the coefficient of friction and the good transparency caused by the special surface, and furthermore, it can be used for packaging that takes advantage of the good transparency caused by the special surface. It can be used in a wide variety of applications, such as capacitors, which take advantage of its good electrical insulation properties. In addition,
The film of the present invention has a surface having a surface morphology within the scope of the present invention, which is a running surface (as a support for a ferromagnetic metal thin film, the surface on which a ferromagnetic metal thin film is not formed), and for other uses such as printing or application of other coating materials. It is desirable to use it as a surface that will not be processed.

Claims (7)

[Claims] (1) A biaxially oriented film whose main components are a thermoplastic resin and inert particles contained in the resin, with the inert particles contained in the resin on the surface not in contact with the ferromagnetic metal thin film. A ferromagnetic metal characterized in that surface protrusions having (A) as a core are formed, and the average height of the surface protrusions is 1/4 or more of the average particle diameter of the inert particles (A). Support for thin films. (2) A support for a ferromagnetic metal thin film, which is obtained by forming an easily slippery film on the surface of the support for a ferromagnetic metal thin film according to claim 1 that is not in contact with the ferromagnetic metal thin film. (3) The ferromagnetic metal film according to claim 1 or 2, characterized in that the surface in contact with the ferromagnetic metal thin film is substantially free of protrusions whose cores are inert particles contained in the thermoplastic resin. Support for magnetic metal thin films. (4) On the surface in contact with the ferromagnetic metal thin film, protrusions are formed with inert particles (B) having a particle size of 150 nm or less dispersed in a thermoplastic resin as nuclei, and the density of the protrusions is 10,000 or less. Claim 1 characterized in that the number of particles/mm^2 or more is
Or the support for a ferromagnetic metal thin film according to claim 2. (5) Organic particles are closely attached to the surface in contact with the ferromagnetic metal thin film to form protrusions, and the average height of the protrusions is 50 nm.
Below, the average protrusion diameter is 100 nm or more, the ratio of both (height /
5. The support for a ferromagnetic metal thin film according to claim 3 or 4, characterized in that the diameter) is 0.3 or less, and the density of the projections is 500,000 pieces/mm^2 or more. (6) A claim characterized in that a non-smooth film having granular, wavy, wrinkled, net-like, mountain-like, or earthworm-like protrusions with a height of 50 nm or less is formed on the surface in contact with the ferromagnetic metal thin film. A support for a ferromagnetic metal thin film according to claim 3, claim 4, or claim 5. (7) A film with a thickness of 50 nm or less containing fine particles with a particle size of 50 nm or less is formed on the surface in contact with the ferromagnetic metal thin film, and the density of the fine particles is 500,000 pieces/mm^2
The support for a ferromagnetic metal thin film according to claim 3, claim 4, claim 5, or claim 6, wherein the support is as follows.