JPH0386542A - Biaxially orientated thermoplastic resin-film - Google Patents

Abstract

PURPOSE:To improve dubbing resistance for the utility of magnetic recording medium, durability in use and the property of drop out by a method in which the number of the protrusions on the film surface formed by the inert particles contained in the layer of a laminated film is set at a specified value or more, and the relative standard deviation of the distribution of the protrusions is suppressed more small than the specified value. CONSTITUTION:The ethylene glycol rally containing crosslinked polystyrene particles and silica particles is prepared, and after the heat treatmet of said material, and after ester-exchanging reaction with dimethylterephthalate has been achieved, they are condensation-polymerized, whereby the pellet of polystyreneterephthlate (PET) containing the particles of 0.3-55wt.% is made. Thermoplastic resin A is prepared by using said pellet, and the PET containing no inert particles is produced as thermoplastic resin B. These polymers are melted and are joint-laminated with a joint block, and then the unoriented film of two layers is made by cooling and solidifying said material. This unoriented film is oriented in longitudinal direction. The number of the protrusions on the surface of this film is at least 10,000/mm, and the relative standard deviation of the height-distribution of said protrusions is 0.7 or less.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a biaxially oriented thermoplastic resin film, and in particular to a biaxially oriented thermoplastic resin film having an @body film structure and having improved surface properties. related to

[Prior art] As a biaxially oriented thermoplastic resin film with improved surface properties, substantially spherical silica particles derived from colloidal silica were contained in poly 1 stell, which is a thermal UJ plastic resin. For example, the film is known as JP-A-5
9-171623>.

In such a biaxially oriented thermoplastic resin film,
The contained silica particles form protrusions on the film surface, lowering the coefficient of friction on the surface and improving handling and running properties, as well as improving the adhesion of the magnetic layer in magnetic recording media applications. It is possible.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional biaxially oriented thermoplastic resin film, the contained silica particles are distributed almost uniformly over the entire thickness direction of the film. There is a limit to the increase in the density of protrusions due to GTJ-containing particles, but the height of the protrusions also varies considerably at random. Recently, the following problems have been pointed out due to the non-uniform height of the protrusions and the low density of the protrusions.

If the height of the protrusions on the surface of the film is uneven, the high protrusions are likely to be scraped, and the film processing process, such as the printing process in J3 for packaging applications, and the magnetic ↑4 internal coating hole in magnetic recording media applications, will be easily scratched. - With the increase in process speeds such as the calender process or the application of a heat-sensitive transfer layer in heat-sensitive transfer applications, the drawback of scratches on the film surface caused by contacting rolls has recently become a problem.

In addition, in certain applications, such as graphic applications, transparency of the film is required, but if the height of the surface protrusions is long, the degree of random light failure increases, resulting in poor transparency. There is.

In addition, recently, magnetic recording media, especially video tapes, are often used for software (recording and fixing produced video works on packaged media, duplicating and multiplying them), but in this case, the above-mentioned conventional For film-based video tapes, the S/N ratio is high when dubbing (copying) from a master tape at high speed during the recording process of a video work.
The problem has also arisen that the signal/noise ratio (signal/noise ratio, image quality parameters) is greatly reduced and the image quality is deteriorated. Also,
It is also desired to improve the durability (low S/N) for repeated use of video tapes or for repeated dubbing.

On the other hand, if the protrusion density on the film surface is low, the effect of improving the slipperiness of the film surface is low, and the expected effects of improving handling and running properties cannot be obtained.

In particular, when handling the film under high temperature and high humidity, the coefficient of friction becomes high and the handling properties become poor.

In addition, on the film surface with protrusions, the other object (
For example, in the processing process, the tip surface of the protrusion mainly contacts the roll), but if the protrusion density is low, the contact 1 "f1 product" by the tip surface becomes small and the contact mj pressure increases, so the resistance of the film surface increases. A problem also arises in wearability.

The present invention achieves a uniform height of protrusions on the film surface and a high density of protrusions in a -axis-oriented thermoplastic resin film, and solves the various problems encountered in the above-mentioned conventional techniques by making the film transparent. Improvement of ↑4, image by dubbing! (Preventing a decrease in S/N> (hereinafter also referred to as dubbing resistance), the durability of the tape in use -f=, J3, and the crushing property -E.

[Means for Solving the Problems] The biaxially oriented thermal iiJ plastic resin film of the present invention that meets this objective is produced by coextruding a film containing thermal 11J plastic resin A and inert particles as main components. A biaxially oriented thermoplastic resin film laminated on a film containing resin B as a main component, wherein the number of protrusions on the film surface formed by the inert particles is 10,000 fI/iI/mrtt'' or more, and , the relative standard deviation of the height distribution of the protrusion is 0
．． 7 or less.

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, the main constituent is at least one structural unit selected from ethylene derephthalate, ethylene α, β-bis(2-chlorophenoxy)ethane-4,4′-dicarboxylate, and ethylene 2,6-naphthalate units. This is desirable because transparency, dubbing resistance, and friction coefficient become even better. In addition, the heat i1 constituting the present invention
When plastic resin is crystalline, it has transparency, dubbing resistance,
This is highly desirable since the coefficient of friction becomes even better.

Crystallinity here indicates that it is not so-called amorphous, and quantitatively, it is determined that the crystallization parameter (cold crystallization temperature Tcc is detected and the crystallization puff meter ΔTCO is 150°C). In addition, when the heat of fusion (change in enthalpy of fusion) measured by differential scanning heating ff1A=t shows crystallinity of 7.5 cal/g or more, transparency, dubbing resistance, and coefficient of friction are better. Polynisder containing ethylene terephthalate as a main component is particularly desirable because it has even better dubbing resistance and transparency.

In addition, two or more types of heat 6.
A plastic resin may be mixed or a copolymer may be used.

The shape of the inert particles in the thermal 11T plastic resin A of the present invention is as follows:
Although not particularly limited, particles with a particle size ratio (major axis/minor axis) of 1.0 to 1.3 in the film, especially spherical particles, make the film surface less likely to be damaged (scratch resistance It is desirable because the transparency becomes good (-PM).

Further, the inert particles in the thermoplastic resin A of the present invention have a single particle index in the film of 0.7 or more, preferably 0.9.
It is particularly desirable that the above is the case since scratch resistance and dubbing resistance become even better.

ii) The type of inert particles in the plastic resin A 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. is not desirable. Preferred particles include substantially spherical silica particles derived from colloidal silica, particles made of crosslinked polymers (for example, crosslinked polystyrene), and in particular, 10% reduction in temperature (at 4 o'clock temperature in nitrogen). Measured using Shimadzu TG-30M. Scratch resistance and dabbing resistance are even better in the case of crosslinked polymer particles whose degree of crosslinking is increased until the temperature rise rate ff 120°C/min) is 380°C or higher. In the case of spherical silica derived from colloidal silica, substantially spherical silica with low sodium content produced by an alkoxide method has better scratch resistance and transparency. However, other particles, such as calcium carbonate, titanium dioxide, alumina, etc., can be used to provide adequate control of film thickness and average particle size.

The size of the inert particles is such that the average particle diameter in the laminated film containing the inert particles is 0.1 to 0.1 to the thickness of the laminated film.
10 times, preferably 0.5 to 5 times, more preferably 1
．． It is said to be in the range of 1 to 3 times. If the average particle size/film thickness ratio is smaller than the above range, the scratch resistance, friction coefficient, and transparency will be poor, and even if it is larger, the scratch resistance, dubbing resistance, and friction coefficient will be poor. This is not desirable.

Also, f! ! , the average particle diameter (west diameter) of inert particles in the film of plastic resin A is o, ooy ~ 0.5 μ flow,
Preferably, the range of 0.02 to 0.45 μ7n is desirable because scratch resistance, dubbing resistance, and friction coefficient become even better.

That is, the laminated film layer in the present invention contains inert particles having an average particle size near or larger than the width of the film. In other words, the pole 21 or the laminated film contains minute active particles having an average particle diameter near the thickness of the film or -b larger than the thickness of the film. Therefore, the inert particles can be distributed in the thickness direction of the entire biaxially oriented thermoplastic resin film, concentrating substantially only on the laminated film layer. As a result, the particle density in the laminated film can be easily increased,
The density of protrusions on the film surface formed by the particles can also be easily increased. In addition, by being included in the laminated film, the inactivating particles are regulated in the thickness direction of the entire biaxially oriented thermoplastic resin film. Since the average particle size has the above-mentioned relationship, the height of the surface protrusions formed by the particles becomes extremely uniform.

A film containing such thermoplastic resin A and inert particles as main components is laminated onto a film containing thermoplastic resin B as main components.

The thermoplastic resin B is made of the same material as the thermo-111 plastic resin A described above, and the thermoplastic resin B and the thermoplastic resin A may be of the same type or different.

The film layer of thermoplastic resin A is laminated onto the film layer of thermoplastic resin B or piece 1a1. In other words, when the laminated configuration is A/B/A or A/B,
Of course, it may be an A/[3/C structure in which a 0 layer having a surface state different from that of A is provided on the opposite side of A, or a multilayer structure having more than that. (Here, the types of thermoplastic resins A, B, and C may be the same or different. Also, at least one surface must be flat.) As thermoplastic resin B. , crystalline polymers are desirable, especially when the crystallinity parameter ΔTCg is in the range of 20 to 100°C, because the dubbing resistance becomes even better.Specific examples include polyester, polyamide, polyphenylene sulfide, and polyolefin. However, polyester is particularly preferable because it has even better dubbing resistance.Also, as polyester,
Ethylene terephthalate, ethylene α, β-bis(2-
[Colphenoxy] It is preferable that the dubbing resistance is particularly good when the main component is at least one structural unit selected from ethane-4,4-dicarboxylate and ethylene 2,6-naphthalate units. . 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 contain other types of polymers within a range that does not impede the purpose of the present invention, and may also contain organic compounds such as antioxidants, heat stabilizers, lubricants, and ultraviolet absorbers. Additives may be added to the extent that they are normally added.

There is no particular need to contain inert particles in the film mainly composed of thermoplastic resin B, but if this film forms one surface of the film, the average particle size is 0.000.
7-2μ7W, especially 0.02-0.45μm inert particles 0.001-0.2% by volume, especially 0.005-0.
When the content is 15% by weight, and even 0.12% by weight, the friction coefficient and scratch resistance are improved.
This is extremely desirable because it not only improves the quality of the film, but also improves the winding appearance of the film. As for the type of inert particles to be contained, it is desirable to use those preferably used for thermoplastic resin A. The types and sizes of particles contained in thermoplastic resins A and B may be the same or different.

The thermoplastic resin A containing inert particles as described above and the thermoplastic resin B are laminated by coextrusion, formed into a sheet, and then biaxially stretched to form a biaxially oriented thermoplastic resin film. be done. M by coextrusion in the present invention
A layer is formed by extruding thermoplastic resin A containing inert particles and thermoplastic resin B using different extrusion devices, []
It refers to laminating these sheets before producing a laminated sheet from gold. This lamination may be carried out in a die (for example, a manifold) for molding and dispensing into a sheet, but since the laminated film layer is extremely thin as described above, it may be carried out in a polymer tube before introducing it into the die. It is preferable to do so. In particular, if the laminated portion inside the polymer tube is formed into a rectangular shape,
This is particularly preferred since it can be laminated uniformly in the width direction. The molten polymer deposited in the rectangular laminated portion in the polymer tube is expanded to a predetermined width in the sheet width direction in the manifold in the die, and after being discharged into a sheet from gold, it is biaxially stretched. Therefore, even if the laminated film layer after two-wheel orientation is extremely thin, in the rectangular laminated part inside the polymer tube, the heated Ti containing inert particles
Since the J plastic resin polymer is laminated to a considerable thickness, it can be laminated easily and cleanly.

The thermoplastic resin film after two-wheel orientation according to the present defense has 10,000 protrusions on the film surface formed by inert particles contained in thermoplastic resin A. / 7F1111
In particular, for various industrial + 4 and goods applications, the number of protrusions is 1): J pieces/mm or more, 5.
Less than 00,000 pieces/rrm2 is preferable. If it is less than this, that is, if the protrusion density is smaller than the above value, the caving resistance will be poor, and if it is more than the above value (if the protrusion density is high),
Transparency deteriorates. Furthermore, in magnetic recording media applications, especially videotape applications, transparency is practically not an issue;
Since dubbing resistance, durability in use of the tape, and dropout are considered problems, the number of protrusions is preferably increased to 500,000 protrusions/darkness 2 or more. When the number of protrusions becomes extremely large as described above, the height of the protrusions described below is also made uniform. Protrusions @ number 5o7. By setting the number of pieces/darkness to 2 or more,
As a videotape, highly desirable dubbing resistance, usage durability, and dropout characteristics can be obtained. J3, the manufacturing upper limit for the number of protrusions is 100 million/
It is about rra2.

In the biaxially oriented thermal IIJ plastic resin film according to the present invention, the relative standard deviation of the height distribution of the protrusions is
Average night stay> is 0.67 or less, preferably 0.6 or less. In other words, it has an extremely uniform height distribution. This 11
If it exceeds @, the transparency↑4 will deteriorate and the film surface will be easily scraped (scratch resistance will deteriorate). Also,
[Norutsugu dubbing ↑1 on videotape, the durability of use is also low.

Furthermore, the biaxially oriented thermoplastic T4 resin film of the present invention is
It is preferable that the Young's modulus in the width direction is 400 Kg/1wrt" or more, and for videotape applications, it is more preferable that the Young's modulus is 400 K in both the width direction and the longitudinal direction.
'j/N! 1" or more is preferable. By laminating the aforementioned rectangular laminated portion in the polymer tube on the right, uniform lamination is possible, and even if the laminated film layer is an extremely thin layer, the width direction stretch ratio is At least three times as much, and a Young's modulus in the width direction of 400 Kg/M2 or more can be easily achieved.

If the Young's modulus is lower than the above value, when a wide film is discharged and slit into narrow widths according to the intended use, powder falling from the slit film end face will be poor, and the generated film powder will cause various problems. This is not preferable because there is a risk. In addition, the Young's modulus in the width direction and longitudinal direction is above f#
J. If the temperature is low, the dubbing resistance as a videotape will be poor.
This is not preferable because there is a risk that the dropout characteristics will deteriorate.

Further, in the biaxially oriented thermoplastic resin film of the present invention, it is preferable that the particle Si ratio of the inert particles in the surface layer on the @ layer film side containing inert particles is 0.1 or less. This surface particle 11 degree ratio is, as shown in the measurement method described below,
This shows how the inert particles forming the film surface protrusions are covered with a thin film of thermoplastic resin A on the film surface. The particles have a high In ratio, and although surface protrusions are formed, the m ratio of the culm surface layer particles, which are covered to a high degree with a thin film of thermoplastic resin A, is low. Since the inert particles forming the protrusions are covered with a thin film of thermoplastic resin A, the inert particles are distributed in a high density in the persimmon:'x9 laminated film layer. is firmly held by the laminated film layer and by extension the base film core of thermoplastic resin B. Therefore, by setting the surface layer particle concentration ratio to be less than or equal to L distribution, falling off of particles, etc. is prevented, and the film surface has scratch resistance and I resistance.
f41; Compassion is maintained at a high level. Such a large particle concentration ratio can be achieved by laminating by coextrusion. By the way, it is also possible to use a coating method to create a film similar to the present invention, that is, to coat a base film with an extremely thin resin layer and to incorporate inert particles into the resin layer. , surface particles′
The a degree ratio becomes significantly higher (that is, the degree to which the particles are substantially directly exposed to the surface becomes significantly higher), and the film of the present invention has only a very high degree of surface CP.

In the film of the present invention, the height of the surface protrusions formed by the inert particles is not particularly limited, but in order to obtain the desired effect of improving slipperiness, It is preferable to set the average particle diameter of the inert particles and the thickness of the laminated film layer of thermoplastic resin A so that the particle diameter is 0.3 times or more. Further, in order to obtain uniform and high-density protrusions, it is preferable that the standard deviation of the particle size distribution of the inert particles themselves is 0.5 or less.

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

First, the inert particles can be incorporated into the thermoplastic resin A by any method after, during, or before polymerization, but the scope of the present invention is to knead the inert particles into the polymer using a vent-type twin-screw extruder. It is effective to obtain a film with a surface morphology of In addition, as a method for adjusting the particle content, a high-concentration master is prepared using the above method, and then diluted with a thermoplastic resin that does not substantially contain inert particles during film formation to adjust the particle content. A controlled method is effective for obtaining a film having a surface morphology within the range of the present invention. Furthermore, this particle height S
A method in which the melt viscosity of the master polymer, copolymerization components, etc. are adjusted to keep its crystallization parameter ΔTcg in the range of 30 to 80°C is effective in obtaining a film with a surface morphology within the range of the present invention without stretching tearing. It is valid.

Thus, pellet A containing inert particles is dried for 1 minute, then fed into a known melt extruder, melted at a temperature above the melting point of the plastic resin and below the decomposition point, and substantially Supplying a thermoplastic resin B that does not contain inert particles (the type may be the same as or different from the thermoplastic resin containing inert particles) to a lamination apparatus as described above,
It is extruded into a sheet through a slit die, cooled and solidified on a casting roll to produce an unstretched film.

That is, using 2 or 3 extruders, 2 or 3 merging blocks or ferrules -C1 these thermoplastic resins! 14 layers. When using the merging block method, the laminated portion is rectangular as described above, and the difference (absolute value) in the melt viscosity of both thermoplastic resins is set to 0 to 2000 voids,
Preferably, the range of 0 to 1000 voids is effective for industrially producing a film having a surface morphology within the range of the present invention stably and without unevenness in the width direction.

Next, this multilayer unstretched film is subjected to two-wheel stretching to achieve biaxial orientation. - The uniaxial stretching method may be either a simultaneous two-wheel stretching method or a sequential two-wheel stretching method, but in the case of a sequential two-wheel 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. No unevenness in the width direction; 1: Effective for manufacturing inside a ditch. In the case of sequential two-wheel stretching, the stretching in the longitudinal direction is divided into 3 stages, especially 4 or more stages, and 40 to 15
A method of stretching 3 to 6 times at a temperature of 0° C. and a stretching rate of 1000 to 500%/min 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 200'C.
A range of 0.00%/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 1
The temperature is preferably 60 to 220°C for 0.5 to 60 seconds, but it is desirable to use microwave heating in combination with the heat treatment (this makes it easier to obtain a film having a surface morphology within the range of the present invention).

In addition, in the state of the product film, the ratio of the thickness t of the thermoplastic resin layer containing inert particles to the average particle diameter (diameter) d of the included inert particles, d/l, is 0.1 to 10, Preferably, it is 0.5 to 5, more preferably 1 to 3, which is extremely effective for producing a film having a surface morphology within the range of the present invention.

Therefore, the appropriate cumulative thickness varies depending on the size of the inert particles used and cannot be generalized, but it is usually 0.00
It is particularly effective in the case of doors with a diameter of 7 to 0.5 μm, preferably 0.02 to 0.45 μm, since the form of Table IR1 within the range of the present invention can be easily obtained.

The manufacturing method of the film of the present invention is characterized by using a highly concentrated anti-particle polymer having thermal properties in a specific range prepared by a special method.
This method involves two-wheel stretching of the film after forming an extremely dirty layer containing inert particles.In the film-forming process, the film is uniaxially stretched, then coated, etc., and further stretched, or biaxially stretched. A laminated film made by coating a film does not come close to the performance of the film of the present invention, and the film of the present invention is also superior in terms of cost.

[Method for Measuring Physical Properties and Evaluating Effects 1 Methods for measuring characteristic values and evaluating effects of the present invention are as follows.

〈1) Average particle size of the particles Polyester is removed from the film by plasma low-temperature ashing process (
For example, the particles are removed using Yamato Scientific Model PR-503. The processing conditions are selected so that the polyester is incinerated but the particles are not damaged. This is SF
IIus with M (scanning electron microscope), and image of the particles (light shading created by the particles) is analyzed with an image analyzer (
For example, Cambridge Instrument QI”M2O
Connecting to 3), we performed the following numerical processing using different observation points and the number of particles was 5000 or more, and the number average l! [) is the average particle size.

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

(2) Particle content A solvent is selected that dissolves the polyester but does not dissolve the particles.The particles are centrifuged from the polyester, and the particle content is defined as the ratio of the particles to the total production (quasi-star %). Depending on deception, the combination of infrared spectroscopy-b is effective.

(3> Glass point shift Tg, cold crystallization temperature TCC1 crystallization parameter Δ-r'cg, melting point Birx Elmer d DSC (differential scanning calorific value Ai>I
It was measured using a t-type. The measurement conditions for DSC are as follows. Sample 10IRg 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 is subjected to 4W at 10'C/min, and the glass transition point -rg is detected. Rough heating was continued, and the peak temperature of the crystallization exotherm from the glass state was defined as the cold crystallization fA degree Tcc. The temperature was continued to rise gradually, and the melting peak temperature was taken as the melting point. Also, the difference between 1°cc and Tg (T'
CC-1'g> is defined as a crystallization parameter ΔTc9.

(4) Relative e of average height, number, and height distribution of surface protrusions!
, semi-deviation two-detector scanning electron microscope [ESM-3200,
The height of the protrusion was measured using an image processing device [IBAS2000, Carl Made by Zeiss 1
and reconstruct the film surface protrusion image on the image processing mounting. Next, in this table 1r "2 protrusions in 1 protrusion image"
The equivalent circle diameter is determined from the area of each protrusion obtained by i#i conversion, 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. In addition, based on the height data of each protrusion, the standard (IIi difference) of the height distribution was determined. The value obtained by dividing the determined standard deviation by the average value of the heights is the relative a standard deviation. In addition, the magnification of the scanning electron microscope is selected between 1,000 and 8,000 times.
1), objective lens: 40 to 200 times, high wl image polishing camera is effective).
-b may be used instead of the value of M.

<5> Using a secondary ion mass spectrum (SIMS) with a surface particle ratio of 1 degree -C, the concentration ratio of the element with the highest concentration among the elements originating from particles in the film and the carbon element of the polyester is defined as the particle concentration. , conduct an analysis in the thickness direction.

The ratio of the particle concentration in the outermost layer measured by SIMS (particle concentration A at the point of depth O and the maximum concentration B obtained by further analysis in the depth direction), A/B is the 1 degree ratio of surface particles. The measuring device and item A4 are as follows.

■ Measuring device Secondary ion mass spectrometer (SIMS) Manufactured by West Germany, ^TOHIK 8 ^He [) ID 8 000■
Measurement conditions Primary ion species: 02 Primary ion accelerating current: 12KV Primary ion current: 200nA Las') -fAtf), : 400 am Analysis area: Gate 30% &M\Vacuum fi: 6. Ox 10' 7orrF
-GUN: 0.5KV-3, OA (6〉The cross section of the single grain index film was examined using a transmission electron microscope (1' FE, M
) to detect particles. Observation magnification 100
If the magnification is about 000 times, a single particle that cannot be separated any further can be detected. When the area occupied by particles is A, 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. 1 [M conditions are as described above, and 500 visual fields are measured by changing the measurement location of 1 visual field area = 2 μm'.

・Equipment 2: JFM1200EX manufactured by JEOL Ltd. ・Observation magnification:
100,000 times Section thickness: Approximately 1000; 1 ng 1-〉-mm (7〉 particle size ratio) - In the measurement of (1), the average length of each particle is 1
There is a ratio C of 10/average value of the short axis.

However, it can be found using the equation.

Major axis = ΣDli/N Minor axis = ΣD2i/N 1) 1i and D2i are the major axis (maximum diameter) and minor axis (!yrj diameter) of each particle, respectively, and N is the total number.

(8>Young's modulus 2 using an Instron type tensile tester according to the method specified in JIS-Z-1702)
Measured at 5°C and 65' CRH.

(9> Thickness of thermoplastic resin A layer in laminated film) Using a secondary ion mass spectrometer (SIMS), it was determined that the interior of particles in the film was also found to have a high concentration of elements originating from particles and carbon elements of polyester. The concentration ratio (M''/C+) of particles is defined as m degrees, and analysis is performed in the direction of depth (thickness) from Table IR1 of the thermoplastic resin Afi1M.In the surface layer, the particle concentration is low due to the interface called the surface and moves away from the surface. As the particle density increases, the particle concentration increases.In the case of the film of the present invention, the particle density once reached the maximum value at depth [1] begins to decrease again.Based on this m density distribution curve, the particle concentration at the maximum value is /2 depth [■] (Here, II>H is taken as the lamination thickness.

The conditions are the same as in measurement method (5).

In addition, the film contains the most 4n'? If the particles are organic polymer particles, it is difficult to measure them with SIMS, so the particles are etched from the surface and then examined using XI)S (X-ray photoelectron spectroscopy), IR (infrared spectroscopy), or a focal microscope. The depth profile of the concentration may be measured and the laminated thickness may be determined using the same method as described above.

Furthermore, the lamination thickness on the thermoplastic resin 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 film height difference measuring device, or the like.

(10) Using a tape running tester, slit the fli1 scrapy film into a tape shape with a width of 1 x 2 inches and run it on a guide pin (surface roughening: Ra of 1100n>7 (running speed polishing 10
00Trt/min, running the same number of 10 passes, wrapping angle: 60
°, running crab 20g>. At this time, the scratches in the film were observed under a microscope, and scratches with a width of 2.5 μTrL or more or less than 2 per tape were considered good; less than 2 scratches per tape was good;
Trees with a diameter of 0 or more were judged to be genuine bark. Excellent is desirable, but even good is practically reusable.

(11) Magnetic paint with the above composition is applied to the durable film with dubbing resistance using a gravure roll, magnetically oriented, and dried.Furthermore, a small test calender device (steel roll/builon roll,
After calendering at a temperature of near 0°C and a line L↓ of 200 at 1/cm, the film was cured at 70°C for 48 hours. The original tape was slit into 1×2 inch pieces to make pancakes.

V T-R from this pancake to a length of 250Tn
It was incorporated into a cassette and used as a VTR cassette tape.

(Composition of magnetic paint) - Co-containing iron oxide (B E 1' f night 50 m2/y
): 100 parts by weight・S-LEC A (vinyl chloride/vinyl acetate copolymer manufactured by Tsukisui Kagaku Co., Ltd.) = 10 double star quasi-star Laporan 2304 (polyurethane elastomer manufactured by Nippon Polyurethane Co., Ltd.) = 10 heavy hanging parts・Cotonate L (Japan Polyurethane Co., Ltd.) polyisocyanate) = 5-layer monomer/lecithin
°1 part by weight methyl edyl ketone
1 part of Nia 5J, 51 tt parts of methyl isobutyl ketone, toluene = 15 parts by weight, carbon black: 2 parts by weight, lauric acid: 1.5 parts by weight This tape was used to generate a TV test waveform made by Shibatsu using a home VTR. 10 by vessel (1' G 7 / U 706)
Record the 0% chroma signal and measure the chroma signal from the reproduced signal using a Shibaku cuff video noise meter (925D/1).
/N was measured and designated as A. In addition, the same sample tape (unrecorded Measure the chroma S/N of the tape after dubbing it to the pancake of
And so. Low chroma S/N due to this dubbing (A-
When B) was less than 3 dB, the dubbing resistance was judged as poor, when it was 3 dB or more and less than 5 dB, it was judged as good, and when it was 5 dB or more, it was judged as poor. Excellent is desirable, but good is still usable for practical purposes.

Add the above dubbed tape to a home VTR for 50 yen.
After 0 passes, the S/N low was measured to evaluate durability in use. When the S/N (low S/N) was less than 2 dB, durability in use was considered to be good.

(12) Set the dropout video tape in the VTR, record the signal from the TV test signal generator (11 Shibaku TG-7/1 type), and then conduct 100 passes at 25°C and 50% R1-1. (12
0 minutes x lOO pass> was run. Using a dropout counter, this tape was picked and marked as a dropout if the width of the dropout was 5 μsec or more and the attenuation of the reproduced signal was −16 db or more.

The measurement was carried out on 10 rolls, and if the number of dropouts that were paralyzed in - minutes was less than 10, the dropout was considered good, and if the number of dropouts was 10 or more, it was judged to be poor.

(13) Static friction coefficient μs The static friction coefficient of the film/film was measured using a Suritsunodesta according to ASTM-D-1894-B-63. When it exceeds 1.5, handling property becomes poor.

<14> Transparency Film haze was measured according to ASTM-D-1003-52.

<15> Speed 19150 Trt using a small slitter for powder drop test on film edge surface
Slit the film at /min. At this time, at a point 10 iJ away from the slit part, wipe 300 m of black Toshi-made Torayshi (eyeglass cloth) lightly touching the culm pressure on both end faces of the film. Visually inspect the Toshichi after wiping. Judgment will be made based on the following criteria.

No powder attached at all 5 points Some powder attached 3 points How much powder is attached to the ant? 1 point 4 points between 5 points and 3 points, 2 points between 3 points and 1 point Point, 3
Those with higher scores were considered to have good powder removal.

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

Examples 1 to 6, Comparative Examples 1 to 3 An ethylene glycol slurry containing 14"g of crosslinked polystyrene particles having different average particle diameters and silica particles caused by co-[1] silica force was prepared, and this ethylene glycol slurry was After heat treatment with C for 1.5 hours, polycondensation was performed after 1 sprue exchange reaction with dimethyl terephthalate, and pellets of polyethylene terephthalate (hereinafter abbreviated as El) containing 4q of particles containing 0.3 to 55% by weight were obtained. Thermoplastic resin A was prepared using these pellets, and PET containing substantially no inert particles was produced using a conventional method to prepare thermoplastic resin B. Each polymer was dried under reduced pressure at 180°C for 3 hours (3
rr> Shita.

Thermoplastic resin A was supplied to extruder 1 and melted at 310°C,
Furthermore, thermoplastic resin B is supplied to extruder 2, melted at 280°C, these polymers are laminated together in a merging block with a rectangular stacking part, and the surface temperature is 30°C using the electrostatic casting method. The film was wound around a casting drum and cooled and solidified to produce an unstretched film with a two-layer or three-layer structure having a thermoplastic resin A layer. At this time, the discharge amount of each extruder was adjusted to adjust the total thickness and the thickness of the thermoplastic resin AffW. (However, in Comparative Example 3, the A layer was single dark). This unstretched film was stretched 4.5 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 -M stretched film was stretched 4.0 times in the width direction at 100°C at a stretching speed i of 2000%/min using a Sudenta, and heat treated at 200°C for 5 seconds at a constant length of 5 to give a total thickness of 15μ7rt. Thermoplastic resin A1fl thickness 0.2~2
1 q of μ-wide biaxially oriented laminated film was prepared. The parameters of the present invention for these films are as shown in Table 1, and when the parameters of the present invention are within the range, the properties of transparency (haze), slipperiness (friction coefficient), and powder falling off the slit end surface are As shown in Table 1, good values were shown, but otherwise a film having good transparency, slipperiness, and powder removal properties could not be obtained.

Examples 7 to 12, Comparative Examples 4 to 6 1'' refers to the production of films for use in magnetic recording media, in which the average particle size of silica particles and crosslinked polystyrene particles was made smaller, and the number of particles was significantly increased. The other manufacturing methods are the same as in the previous example.

As shown in Table 2, by setting each parameter within the range of the present invention, good dubbing resistance, durability, and dropout characteristics can be obtained.

[Effects of the Invention] As explained below, when using the biaxially oriented thermoplastic resin film of the present invention, it is possible to specify the number of protrusions on the film surface formed by the inert particles contained in the laminated film. Since the relative standard deviation of the protrusion height distribution is kept small below the specified value f + ff, it is possible to improve the protrusion density on the film surface and make the protrusion height uniform. For graphic applications, it is possible to particularly improve transparency, slipperiness, and powder falling properties from the slit end face, and for magnetic recording media applications, it is particularly effective for dubbing resistance and durability in use. , the dropout characteristics can be improved.

In addition, the film of the present invention is a film made by direct compounding by coextrusion without any operations such as C1]-filling during the film-forming process, and can be applied to a laminated film made during the film-forming process or by subsequent coating. In comparison, since the molecules in the outermost layer are also biaxially oriented, in addition to the above-mentioned properties, for example, surface abrasion resistance is far superior, and it is advantageous in terms of cost and quality stability.

Claims (1)

[Scope of Claims] 1. A biaxially oriented thermoplastic resin film in which a film mainly composed of thermoplastic resin A and inert particles is laminated by coextrusion onto a film mainly composed of thermoplastic resin B. , the number of protrusions on the film surface formed by the inert particles is 10,000/mm^2 or more, and the relative standard deviation of the height distribution of the protrusions is 0.7 or less. biaxially oriented thermoplastic resin film. 2. The biaxially oriented thermoplastic resin film according to claim 1, wherein the average particle diameter of the inert particles is in the range of 0.1 to 10 times the thickness of the laminated film containing the inert particles. 3. The biaxially oriented thermoplastic resin film according to claim 1, which has a Young's modulus in the width direction of 400 Kg/mm^2 or more. 4. The biaxially oriented thermoplastic resin film according to claim 1, wherein the particle concentration ratio of the inert particles in the surface layer on the side of the laminated film containing the inert particles is 0.1 or less. 5.Claim 1, wherein the thermoplastic resin A is a crystalline resin.
The biaxially oriented thermoplastic resin film described.