JPH03207727A - Biaxially oriented thermoplastic resin film and film roll - Google Patents

Abstract

PURPOSE:To obtain the subject film having surface protrusions originated from particles, exhibiting excellent scratch resistance and giving a magnetic recording medium having high picture quality by forming a composition composed of a thermoplastic resin and particles in the form of a film and biaxially drawing the film. CONSTITUTION:A thermoplastic resin (preferably a polyester composed of ethylene terephthalate, etc.) is compounded with preferably 2-30wt.% of particles (preferably crosslinked polystyrene particles, etc.), the resin composition is extruded in the form of a film under melting and the film is biaxially drawn to obtain the objective film having surface protrusions on at least one surface and resistant to creasing even after leaving over a long period in the form of a roll. The areal ratio of the protrusion is 6-90%, the flat part is preferably free from undulation, the undulation index is <=50nm and the number of protrusions having a height corresponding to <=1/3 of the average height is <=15% of the total number of protrusions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a biaxially oriented thermoplastic resin film and a film roll formed by winding the same.

[Prior Art] As a biaxially oriented thermoplastic resin film, a film made of polyester containing inert inorganic particles is known (for example, JP-A-59-171623).

Further, as a thermoplastic resin film roll, there is known a thermoplastic resin film roll in which the relationship between the center line average roughness (Ra) of the film and the winding hardness is within a specific range (for example, JP-A-57-193322 Publication No.).

[Problem to be solved by the invention]

However, the above conventional biaxially oriented thermoplastic resin film
As the speed of film processing processes, such as the printing process for packaging applications and the magnetic layer coating/calendering process for magnetic media applications, increases, the problem of scratches on the film surface caused by contact rolls has recently become a problem. It has become to. In addition, recent magnetic recording media are required to have increasingly high image quality, and the surface of the base film is It is becoming increasingly smooth. However, when the surface of the film becomes smooth, the coefficient of friction during running increases, so there is a problem that scratches are more likely to occur during high-speed running.

Furthermore, during distribution and storage, film is normally wound in a film roll wound around a core made of plastic or paper, but depending on the atmosphere and time in which the film roll is placed, In some cases, the material had wrinkles and the like, making it impossible to use it for post-processing.

In this conventional thermoplastic resin film roll, wrinkles that occur over time cannot be completely eliminated, and due to these wrinkles, the smoothness of the film is poor. For example, when used as a base film for a magnetic recording medium, the S/N There was a problem in that the electrical characteristics deteriorated when used for capacitors and capacitors.

The present invention has solved these problems, and can be used as a magnetic recording medium without being scratched (hereinafter referred to as "good scratch resistance"), has a high S/N ratio when used as a magnetic recording medium, and can be used as a film roll for a long time. To provide a film and a film roll that are resistant to wrinkles even when left alone.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a film whose main component is a composition consisting of a thermoplastic resin and particles, with respect to surface protrusions formed on at least one side of the film. , a biaxially oriented thermoplastic resin film characterized in that the area ratio of the protruding portions is in the range of 6 to 90%, and a film roll using the same.

Although the thermoplastic resin in the present invention is not particularly limited, it is preferable that the thermoplastic resin is a crystalline polymer because the protrusion structure of the present invention can be easily obtained and the scratch resistance will be even better. Crystallinity here 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. or less. Furthermore, the heat of fusion (enthalpy of fusion change) measured with a differential scanning calorimeter
When the crystallinity is 7°5 cal/g or more, the scratch resistance becomes even better, which is extremely desirable. Specific examples include polyester, polyamide, polyolefin, polyphenylene sulfide, etc. Polyesters, particularly ethylene terephthalate, ethylene α,β-bis(2-chlorophenoxy)ethane-4,4=dicarboxylate, It is preferable to use a polyester containing at least one structural unit selected from ethylene 2,6-naphthalate units as a main constituent, since the effect of the protrusion structure of the present invention is more pronounced.

The type of particles in the thermoplastic resin 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 preferable, and particles S,/N when the sphericity of is 1.6 or less, preferably 1.5 or less, more preferably 11.3 or less.

This is particularly desirable since it provides even better scratch resistance. Furthermore, it is effective to use particles whose relative standard deviation of particle size distribution is 0.6 or less, preferably 0.5 or less, in order to obtain the protrusion structure of the present invention. Particles that satisfy the above characteristics include substantially spherical silica particles derived from colloidal silica, particles made of crosslinked polymers (for example, crosslinked polystyrene), but in particular, the temperature at 10% weight loss (thermogravimetric in nitrogen) Measured using analyzer Takashi TG-30M.

Scratch resistance, S
/N is particularly desirable. 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 by appropriately controlling the layer thickness and average particle size as described below.

Although the average particle size of the particles is not particularly limited and the preferable range varies depending on the type, it is particularly preferable that the average particle size is 0.01 to 1 μm because the S/N and scratch resistance are even better.

The film of the present invention has the above-mentioned composition as a main component, but other polymers may be blended or copolymerized within a range that does not impede the purpose of the present invention, and antioxidants, heat stabilizers, lubricants, Inorganic or organic additives such as ultraviolet absorbers and nucleating agents may be added to the extent that they are normally added.

The film of the present invention is a film in which the above composition is biaxially oriented. An unstretched film is undesirable because it has poor scratch resistance, and a film produced by coating and stretching in which only the surface portion is uniaxially oriented cannot satisfy the scratch resistance. That is, it is desirable that the polymer molecules near the characteristic surface of the film (the surface having the unique surface protrusions defined by the present invention) be biaxially oriented. The degree of biaxial orientation is not particularly limited, but if the Young's modulus of the film, which represents the degree of molecular orientation, is in both the longitudinal and width directions,
350 kg/mm2, preferably 400 kg/m
m 2 or more is particularly desirable because the scratch resistance becomes even better. Furthermore, the molecular orientation in the extreme surface layer can be confirmed by total reflection Raman method, infrared spectrum, etc.

Regarding the surface protrusions formed on at least one side of the film of the present invention, the area ratio of the protrusions is 6 to 90%, preferably 15 to 85%, and more preferably 20 to 80%.
It is necessary to be within the range of . The term "protrusion" as used herein can be recognized from a surface photograph taken using a differential interference microscope, but more quantitatively it refers to a protrusion with a height of about 15 nm or more that can be recognized as a protrusion using a two-power scanning electron microscope. If the area ratio of the protruding portion is smaller than the above range, the S/N ratio will be poor, and if it is larger, the scratch resistance will be poor, which is not preferable.

Further, the film of the present invention is particularly desirable when there is no undulation in the flat portion other than the above-mentioned protruding portions, since the scratch resistance and S/N ratio are even better. Such waviness is often caused by the pushing up of particles contained inside the film, but waviness due to pushing up of particles inside the film can be recognized even in surface photographs taken with a differential interference microscope (
(see drawing), and more quantitatively, the height amplitude is less than IQnm using a stylus surface roughness meter, non-contact surface roughness meter, or dual detection power type scanning electron microscope, etc. It is particularly desirable that In addition, if this local measurement is difficult, frequency analysis is performed on the surface roughness curve of the film surface to extract waviness with a wavelength of 50 μm or more, and from the size of the waviness, determine the waviness in the flat area other than the protruding parts. It can be determined that it is desirable that the waviness index, which is the amplitude of the waviness, is 50 nm or less, preferably 40 nm or less. Another way of looking at it is that 2
Using a scanning electron microscope with a detection power type, it was found that the ratio of protrusions with a height of 1/3 or less of the average height of surface protrusions to the total number of protrusions was less than 15%, and there was no undulation in the flat area. It represents that.

The film of the present invention has the above-mentioned characteristics, and the relative standard deviation of the protrusion height distribution on the surface is 0. 6 or less, preferably 0.55
Below, it is more preferable that the ratio is 0.5 or less because the S/N and scratch resistance become even better.

The film of the present invention has the above-mentioned characteristics, and the thickness of the thermoplastic resin skin (skin) on the particles in the protruding portion of the surface is 5 to 50 mm.
0. scratch resistance in the range of nm, preferably 10 to 400 nm, more preferably 10 to 150 nm,
This is desirable because the S/N ratio becomes even better.

The film of the present invention is normally distributed in rolls where the film is wound around a core made of plastic or paper.
If the film roll is wound with preferably 40% or less film, and more preferably 35% or less, wrinkles will not occur even if the distribution and storage time until the film roll is used is long. desirable.

Although the type of core is not particularly limited, it is preferable to use plastic because it provides a particularly good winding appearance.

Further, it is preferable that the inner diameter of the core is 1 inch or more, preferably 3 inches or more, since this results in a particularly good winding appearance.

Further, it is preferable that the thickness of the core is 3 mrn or more, particularly 5 mm or more, since this results in a good winding appearance.

In the film of the present invention, the average diameter of the surface protrusions formed on the film surface having the above characteristics is 25 to 1500 nm, preferably 30 to 101000 nm, and more preferably 40 to 600 nm.
A range of m is desirable because scratch resistance and S/N ratio are even better.

The film of the present invention has a surface layer particle concentration ratio measured by a secondary ion mass spectrum of the surface having the above-mentioned characteristics, which is not particularly limited, but the surface layer particle concentration ratio of the film surface having the above-mentioned specific surface protrusions is 1/10 or less. , especially 11
A value of 50 or less is particularly desirable because the friction coefficient and scratch resistance become even better.

The film of the present invention has an S/
N is desirable because it provides even better scratch resistance.

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

First, particles can be incorporated into a given thermoplastic resin by adding them before, during, or after polymerization, but in the case of polyester, they are mixed and dispersed in the diol component in the form of a slurry. The method of addition is effective for satisfying the surface morphology parameters of the present invention. In addition, as a method for adjusting the particle content, a method is used in which a highly concentrated master polymer is diluted during film formation, and the melt viscosity of the master polymer is lower than the melt viscosity of the thermoplastic resin to be diluted, preferably 100%. It is effective to keep the surface morphology parameters of the present invention as low as ~600 voids.

After drying the thermoplastic resin pellets (referred to as thermoplastic resin A) containing 2 to 30% by weight of particles as necessary, the pellets are fed to a known melt extruder and extruded into a sheet through a slit-shaped die. The film is extruded into a shape (7) and cooled and solidified on a casting roll to produce an unstretched film. In this case, using a known film forming apparatus for laminated sheets (for example, two or three extruders, two or three layer merging blocks or manifolds, etc.), the particle content can be reduced to 1 of that of the thermoplastic resin composition A. It is effective to obtain the surface morphology parameters of the present invention by forming an unstretched film with a 2- to 3-layer structure laminated on a thermoplastic resin B composition of /4 or less (B and A are the same or different types). . In addition, in a laminating device, 1.
In particular, it is desirable to have a merging block installed upstream of the mouthpiece.
A rectangular shape with an aspect ratio of 2 or more is extremely effective in keeping the unevenness of the protrusion area ratio in the width direction within a desirable range.

Moreover, a layer made of the above-mentioned thermoplastic resin A (layer A).

In order to satisfy the surface morphology parameters of the present invention, the melt viscosity of the thermoplastic resin used for the surface layer (surface layer) should be lower by about 150 poise, preferably about 300 poise, than the melt viscosity of the thermoplastic resin of other layers in contact with it. It is effective for

Further, the method of installing a static mixer and a gear pump in the polymer flow path of the thermoplastic resin of layer A is extremely effective in satisfying the surface morphology parameters of the present invention without causing any stretching breakage. Furthermore, keeping the crystallization parameter ΔTcg of the thermoplastic resin A of the layer A smaller than the ΔTcg of the thermoplastic resin of other layers in contact with it, preferably smaller than 10°C, satisfies the surface morphology parameters of the present invention. It is extremely effective.

Next, this unstretched film is biaxially stretched and biaxially oriented. As the stretching method, a sequential biaxial stretching method, a simultaneous biaxial stretching method, or a tubular stretching method can be used. However, use a sequential biaxial stretching method in which stretching is first carried out in the longitudinal direction and then in the width direction, and the stretching in the longitudinal direction is carried out at a temperature ranging from 10°C lower to 10°C higher than the glass transition point of the thermoplastic resin. is extremely effective in satisfying the surface morphology parameters of the present invention. As for the stretching method in the width direction, a method of stretching in a temperature range from 10° C. lower than the glass transition point to 30° C. higher than the glass transition point is effective for satisfying the surface morphology parameters of the present invention. The stretching ratio is preferably 2.5 to 7 times in both the longitudinal and width directions,
In addition, the total area magnification (vertical edge magnification x total horizontal magnification) is 8 times or more,
Preferably, it is effective to make it 10 times or more to satisfy the surface morphology parameters of the present invention. Further, when used for applications requiring mechanical strength, the two-wheel stretched film may be further stretched again in at least one direction. Next, this stretched film is heat treated, and a known method can be used. However, the lamination thickness t (nm) of layer A in the final film state and the average particle diameter d of the particles contained in that layer
(nm), 0°1≦t/d≦3, preferably 0°3≦t/d≦1.5, more preferably 0.4≦
Adjusting the discharge rate and stretching ratio so that t/d≦0.9 is extremely effective in satisfying the surface morphology parameters of the present invention. Moreover, the thickness of the A layer is 0.03 to 0.0.
Setting the thickness to 5 μm is extremely effective in satisfying the surface morphology parameters of the present invention.

Note that even a film with a single layer structure can satisfy the surface morphology parameters of the present invention by adjusting the melt viscosity of the particle master polymer, introducing a gear pump or static mixer into the polymer flow path, strictly adjusting the stretching conditions, or using solution casting. Although it is not impossible to do so, there are problems with stability, reproducibility, etc., and this is not preferred industrially.

The biaxially stretched film thus obtained is first wound up as an intermediate spool, then set in a slitter that uses a combination of center wind and surf ace wind, and slit into a predetermined width. The film roll of the present invention is usually completed by winding the film to a length of 1000 m or more.

[Method for Measuring Physical Properties and Evaluating Effects j Methods for measuring characteristic values and evaluating effects of the present invention are as follows.

(1) Content of particles Select a solvent that dissolves thermoplastic resin pellets but not particles, centrifuges the particles from the thermoplastic resin, and defines the particle content as the ratio (wt%) to the total weight of the particles.

(2) Crystallization parameter ΔTcg, heat of fusion measured using a differential scanning calorimeter (DSC).

The DSC measurement conditions are as follows. That is, sample 1
0 mg was placed in a DSC apparatus, melted at 300° C. (7) 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 Tg
Detect. The temperature was continued to be gradually raised, and the exothermic peak temperature of crystallization from the glass state was defined as the cold crystallization temperature Tcc.

The temperature was continued to rise gradually, 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.

(3) Cross-sectional observation of the film ・Equipment: Field emission scanning electron microscope (Hitachi model 5-soo type) ・Accelerating voltage: 10 kV ・Cutting: Carbon vapor deposition on the cut surface using a freezing microtome to create a measurement sample (the cutting direction is the film (lateral direction) (4) Epidermal thickness of the protrusion part Observations were made focusing only on the protrusion part in (3) above, and the protrusion 1
The average value of 0.00 was taken as the epidermal thickness.

Note that similar values can also be obtained by the Rutherford backscattering method from the surface.

(5) Particle Size The thermoplastic resin is removed from the surface of the film by plasma low-temperature ashing treatment to expose particles near the surface.

The processing conditions are selected so that the thermoplastic resin is incinerated but the particles are not damaged. This was scanned using a scanning electron microscope (
SEM) and process the image of the particles with an image analyzer. The following numerical processing is performed when the number of particles is 5,000 or more while changing the observation location, and the number average diameter obtained thereby is taken as the average particle diameter.

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

(6) Sphericity In the measurement of (5) above, it is the ratio of (average value of major axis)/(average value of minor axis) of individual particles. That is, it can be obtained using the following formula.

Major axis - ΣDli/N Minor axis = ΣD2i/N Dli, D2i is the major axis (maximum diameter) and minor axis (shortest axis) of each individual particle, and N is the number of particles.

(7) Relative standard deviation of particle diameter The individual particle diameter Di1 average mean diameter 0 (=(Σ(Di −D) 2/N)'') measured by the method in (5) above is expressed as the average diameter. It is expressed as the divided value (σ/D).

(8) Content of particles Select a solvent that dissolves the thermoplastic resin but does not dissolve the particles, centrifuges the particles from the thermoplastic resin, and defines the particle content as the ratio (% by weight) to the total weight of the particles. In some cases, infrared spectroscopy may also be effective.

(9) Protrusion area ratio, average protrusion height, height distribution 2-detector scanning electron microscope [ESM-3200,
manufactured by Elionix Co., Ltd.] and a cross-sectional measuring device [PMS-1,
Image processing device II
[I BAS2000, manufactured by Carl Zeiss Co., Ltd.], and an image of the protrusions on the film surface is reconstructed on an image processing device. Next, the area ratio of the protrusions is determined by dividing the sum of the areas of the individual protrusions obtained by binarizing the protrusions using this surface protrusion image by the measurement unit area. 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. These measurements were repeated 500 times at different locations, and the protrusion area ratio and average height were determined. Also, based on the height data of individual protrusions,
The standard deviation of the height distribution was determined. The relative standard deviation is the standard deviation divided by the average height. 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 Co., Ltd., objective lens:
40 to 200 times, use of a high-resolution camera is effective) may be read as the above-mentioned SEM value and used.

(10) Width direction unevenness of protrusion area ratio Measure the protrusion area ratio of the film in the width direction of the roll, and divide the difference a between the maximum and minimum values by the average value, a / b. The value (%) multiplied by 100 was taken as the lamination thickness unevenness. However, 10 mr at both ends of the film roll
The total width, excluding the width n, was divided into 50 equal parts, and the center of each equal part was measured.

(11) Surface roughness Measured using a surface roughness meter. The conditions were as follows, and the average value of 20 measurements was taken as the value (Koita Institute ET-10).

・Stylus tip radius = 0.5μm ・Stylus load: 5mg ・Measurement length: 1mm ・Cutoff value + 0.08mm (12) Import the surface roughness curve from the above measurement without the waviness index cutoff value and perform frequency analysis. The waviness component with a wavelength of 50 μm or more was extracted and its maximum amplitude was defined as the waviness size. The measurement was carried out 20 times and the average value was taken as the value (Sobita Institute ET-10).

(13) Using a laminated thickness secondary ion mass spectrometer (SIMS), the elements originating from the particles with the highest concentration among the particles in the film within a depth of 6000 nm from the surface layer and the carbon element of the thermoplastic resin were determined. The concentration ratio (M+/C+) is defined as the particle concentration, and analysis is performed in the thickness direction from the surface to a depth of 6000 nm. In the surface layer, the particle concentration is low because of the interface called the surface, and the particle concentration increases as you move away from the surface. In the case of the film of the present invention, the particle concentration that once reached a maximum value usually begins to decrease again. Based on this concentration distribution curve, the depth at which the surface layer particle concentration becomes 1/2 the maximum value (this depth is deeper than the maximum value) was determined, and this was determined as the lamination thickness. The conditions are as follows.

(1) Measuring device Secondary ion mass spectrometer (SIMS) West Germany, ATOMIl [A-DID^3000 manufactured by Company A]
2) Measurement conditions Primary ion species: 02 Primary ion acceleration voltage: 12KV Primary ion current: 200nA Raster area = 400μm Mouth analysis area: Gate 30% Measurement vacuum degree: 5. OX 10-9TorrE-G
UN:0. 5KV-3, OA, depth 3 from the surface layer
If 81MS measurement is difficult, such as when the particles that are most abundant in the 000 rxm range are organic polymer particles, etching from the surface can be performed using XPS (X-ray photoelectron spectroscopy).
The laminated thickness can be determined by measuring the same depth profile as described above using , TR (infrared spectroscopy), etc., or the interface can be recognized from changes in particle concentration and differences in contrast by cross-sectional observation using an electron microscope, etc. It is also possible to determine the lamination thickness.

(14) Young's modulus 25
Measured at 65% RH.

(15) Using a melt viscosity enhancement type flow tester at 290°C and a shear rate of 20
Measured at 0 sec-1.

(16) Surface layer particle concentration ratio Using secondary ion mass spectroscopy (SIMS), 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 thermoplastic resin 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: 02 Primary ion acceleration voltage: 12KV Primary ion current: 200n^ Raster area 2400μm Analysis area: Gate 30% Measurement vacuum degree: 6. OX 10-'TorrE-
GUN: 0.5KV-3,0A (17) 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 two-wheel orientation of the polymer has a refractive index of N in the longitudinal direction, width direction, and thickness direction.
1, N2, and N3, the absolute value of (Nl − N2 ) is 0.07 or less, and N3 / [(Nl + N2
)/2] is 0.95 or less. Alternatively, the refractive index may be measured using a laser refractometer. Furthermore, if measurement is difficult with this method, total internal reflection laser Raman method can also be used.

Laser total internal reflection Raman measurement is performed by Jobin-Yvan
The total reflection Raman spectrum was measured using a Ramanor U-1000 Raman system manufactured by
In the case of Detection of light parallel to Y, XX: Set the polarization direction of the laser to X.
It is possible to take advantage of the fact that the detection of light parallel to the molecule corresponds to the molecular orientation. The biaxial orientation of a polymer can be determined by converting the parameters obtained from Raman measurement into refractive indices in the longitudinal direction and width direction, and based on their absolute values, differences, etc. 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 (Hamamat@u C12
30) (supply 1600V) ■Measurement conditions 5LI7 1000At1 000At loOmW GATE TIME t, 0secSCAN
5PEED 12cm-'/minSAMP
LING INTERVAL [1,2cm -
'R, EPEAT TIME 6 (18) When used as a magnetic recording medium, a magnetic paint was applied to the S/N film using a gravure roll to a dry thickness of 3 μm. The magnetic paint was prepared as follows.

・Fe (iron) 100 parts Average particle size Length: 0.3 μm Acicular ratio: 10/1 Coercive force 20[100e ・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 2 parts After mixing and dispersing the above composition in a ball mill for 48 hours, adding 6 parts of a hardening agent and filtering the resulting kneaded product with a filter to prepare a magnetic coating liquid, Coated on the above film and oriented in a magnetic field,
Dry at 110°C and use a small test calendar device (
Steel roll/nylon roll, 5 stages) at 70℃,
Linear pressure: After calendering at 200 kg/cm, it was wound into a roll and cured at 50°C for 48 hours, resulting in a width of 8.
A magnetic recording tape was obtained by slitting the tape into mm pieces.

This magnetic recording tape was installed in a VTR cassette, and a home VTR was used to run a Sibaku TV test waveform generator (
A 100% chroma signal was recorded using a TG7/U706), and the chroma S/N was measured from the reproduced signal using a Shibaku color video noise measuring device (925D/1).

This chroma S/N was measured using a commercially available Hi8 tape (8 mm VTR tape for high band, H manufactured by 5ONY).
i8MP120), when the S/N was higher by 1 dB or more, it was determined that the S/N was good, and when it was less than 1 dB, it was determined that the S/N was poor.

(19) Scratch resistance In an atmosphere of 20°C and 60% relative humidity, a tape-like film with a width of 2 inches per section is attached to a guide pin with an outer diameter of 6 mmφ at an angle θ=
π/2 (rad), tension T1 ”200g, 10
After running 30 times at a speed of 0.00 m/min, the surface of the film was aluminum-deposited, and the number of scratches, width, and state of white powder generation were observed using a differential interference microscope. Scratch resistance: No scratches and almost no white powder.
4. Scratch resistance = less than 3 scratches and almost no white powder generation 23. Scratch resistance = 3 to 10 scratches, some of them wide, and white powder generation = 2. Some items have 10 or more scratches and are wide.
The scratch resistance was determined to be 1 if the generation of white powder was observed to be severe. If the scratch resistance is 4 or 3, there is no practical problem (it can be used).

(20) After leaving the rolled film roll in an atmosphere with a temperature of 40°C and a humidity of 80% RH for 6 months, the roll was observed and wrinkles (longitudinal,
The occurrence status in the width direction was checked.

The surface layer 2 of the roll is the one with no wrinkles at all.
Winding condition: Good, with wrinkles occurring only in the 00m section.
Those with wrinkles extending beyond 200 m to the inner layer were judged to be defective. Winding appearance: Excellent is desirable, but good is still usable for practical purposes.

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

Examples 1 to 6, Comparative Examples 1 to 3 Silica particles derived from colloidal silica with different average particle sizes, polyethylene terephthalate containing divinylbenzene/styrene copolymer crosslinked particles, polyethylene-2,
6-naphthalate was prepared (thermoplastic resin A). This thermoplastic resin A and various thermoplastic resins (B) are respectively supplied to extruder 1 and extruder 2, melted at 290°C, these polymers are merged and laminated, and the surface temperature is adjusted using an electrostatic casting method. It is wrapped around a casting drum at 45°C, cooled and solidified, and then changed to a merging device to form two layers (A/B).
) or three-layer (A/B/A) structured unstretched films. Further, the thickness of the thermoplastic resin A layer was adjusted by adjusting the discharge amount of each extruder. This unstretched film
0°C (when layer B is polyethylene terephthalate), 1
．． It was stretched 4.0 times in the longitudinal direction at 40°C (layer B is polyethylene-2,6-naphthalate). This -axially stretched film was stretched 4.2 times in the width direction using a stenter at the same temperature as the longitudinal direction stretching, and then heat treated at 200°C for 5 seconds under a constant length to achieve biaxial orientation with a total thickness of 15 μm. A laminated film was obtained. The parameters of the present invention for these films are as shown in Table 1, and when the parameters of the present invention were within the range, the scratch resistance and S/N were good as shown in Table 1. If not, scratch resistance, S/
A film satisfying N was not obtained. Note that Figure 1 shows the surface condition of the film of Example 1, and Figure 2 shows the surface condition of the film of Comparative Example 3. It can be seen that the film of Comparative Example 3 has undulations in areas other than the protrusions, whereas the film of Comparative Example 3 is flat.

Examples 7 to 9, Comparative Examples 4 to 6 In the same manner as in Examples 1 to 6 above, the cross-sectional shape of the merging portion of the thermoplastic resin of the laminating device was changed in various ways, such as a rectangular shape with a different aspect ratio, a round shape, etc. Films with a thickness of 15 μm with different protrusion area ratios in different directions were made, and the intermediate spools of these films were set in a slitter using a combination of Center Wind and Surf Ace Wind to slit them into a width of 1100 mm, and then a length of 1500 mm. A film roll was prepared by winding a film length of 10,000 m around a Bakelite core with an inner diameter of 6 inches.

These film rolls were left in an atmosphere of 40° C. and 80% RH for 6 months, and then the appearance of the rolls was examined. Those within the scope of the present invention were rated as excellent or good in roll appearance, while those outside the scope of the present invention were poor (Table 2).

[Effects of the Invention] Since the present invention has a special surface morphology parameter on at least one side of the film, it will not be scratched even when running under severe conditions such as high speed running, and the film can be left as a roll. The film does not wrinkle, and therefore the surface of the magnetic layer of a magnetic recording medium using it has a unique shape, making it possible to create a magnetic recording medium with a high S/N ratio, that is, high image quality. In addition, the film produced by this method has a feature that the skin thickness is thicker than that of a film made by applying a paint containing particles to the film surface, or by stretching the film after applying it, and as a result, the S/N It has high scratch resistance and excellent industrial productivity.

Applications of the film of the present invention are not particularly limited, but include magnetic recording media such as video tapes, floppy disks, video floppies, audio tapes, and memory tapes, particularly high-density recording 8mm video, 3mm high band video, and 5VHS. For video, digital video,
It is useful for high-density magnetic recording media such as HDTVs, video tapes for software that are frequently used, and the like.

In addition, film scratches occur in almost all uses of film.
For example, it is useful for packaging, graphics, electrical materials such as capacitors, etc., because it causes problems in process and performance.

In addition, since the unevenness of the area ratio of the protrusions in the width direction was set within a specific range, air removal in the width direction was made more uniform, resulting in a film roll that did not wrinkle when left alone. .

[Brief explanation of drawings]

FIG. 1 is a surface micrograph showing the surface crystal structure of the film obtained in Example 1 of the present invention, and FIG. 2 is a surface microphotograph showing the surface crystal structure of the conventional film obtained in Comparative Example 3. It is. The magnification will eventually be 1000x.

Claims (8)

[Claims] (1) A film whose main component is a composition consisting of a thermoplastic resin and particles, in which the surface protrusions formed on at least one side have an area ratio of 6 to 90.
%. (2) Claim (1) characterized in that the film surface having the protrusions has no undulations on the flat surface other than the protrusions.
The biaxially oriented thermoplastic resin film described. (3) The biaxially oriented thermoplastic resin film according to claim 1 or 2, wherein the film surface having the protrusions has a surface waviness index of 50 nm or less. (4) Regarding the film surface having such protrusions, protrusions with a height of 1/3 or less of the average height of the protrusions account for 15% of the total number of protrusions.
The biaxially oriented thermoplastic resin film according to any one of claims (1) to (3), which is as follows. (5) The biaxial orientation heat according to any one of claims (1) to (4), wherein the film surface having projections has a relative standard deviation of projection height distribution of 0.6 or less. Plastic resin film. (6) Regarding the film surface having the protrusions, the thickness of the thermoplastic resin skin on the particles in the protrusions is 5 to 500 nm.
The biaxially oriented thermoplastic resin film according to claim 1, wherein the biaxially oriented thermoplastic resin film is within the range of (1) to (5). (7) A film roll formed by winding the biaxially oriented thermoplastic resin film according to any one of claims (1) to (6). (8) Regarding the surface protrusions formed on at least one side of the film, the area ratio of the protrusions in the film width direction is not more than 50%. Plastic resin film roll.