JP2567964B2 - Biaxially oriented thermoplastic resin film - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a biaxially oriented thermoplastic resin film, and more particularly to a laminated film structure having an improved surface property, which is most suitable for a film for a magnetic recording medium. Relates to a biaxially oriented thermoplastic resin film.

[Prior Art] As a biaxially oriented thermoplastic resin film with improved surface properties, a film in which a thermoplastic polyester resin contains substantially spherical silica particles derived from colloidal silica is known. (For example, see JP-A-59-17)
1623 publication).

In such a biaxially oriented thermoplastic resin film, due to the silica particles contained, projections are formed on the film surface, and the friction coefficient of the surface is lowered to improve the handling property and the running property, and the magnetic recording medium is used. It is possible to improve the adhesiveness of the magnetic layer and the adhesiveness of the ink for printing.

[Problems to be Solved by the Invention] However, in the biaxially oriented thermoplastic resin film disclosed in JP-A-59-171623, since the contained silica particles are randomly distributed over the entire thickness direction of the film, There is a limit to the increase in the density of the protrusions due to the contained particles on the film surface, and the heights of the protrusions also vary considerably at random. Therefore, there is a limit in improving the film running property by reducing the friction coefficient, improving the scratch resistance of the film surface (hereinafter referred to as scratch resistance) and scratch resistance, and improving the adhesiveness of the magnetic layer and ink.

Therefore, although the application has not yet been published, the applicant of the present invention has previously identified a biaxially oriented thermoplastic resin film having a laminated constitution of the thermoplastic resin A and the thermoplastic resin B, which is specified as the thermoplastic resin A. A biaxially oriented thermoplastic resin film has been proposed in which particles of a size are concentrated and contained to improve the surface properties of the film on the thermoplastic resin A side. With this proposal, it becomes possible to efficiently form high-density, high-density and uniform protrusions on the film surface, and to significantly improve runnability, scratch resistance, abrasion resistance, and adhesion to the magnetic layer and ink. It has become possible to raise it.

As a result of further studies by the present inventors, it was found that the biaxially oriented thermoplastic resin film proposed above can be further improved in film surface properties depending on the application by laminating another layer. The present invention has been completed.

That is, the present invention improves the scratch resistance and abrasion resistance of the film by forming protrusions of a desired height on the film surface with a high density and a uniform height, as compared with the conventionally known film. By further adding another layer to, various properties depending on the application, particularly the adhesiveness with the magnetic layer in the magnetic recording medium application, the antistatic property, the adhesiveness with the ink in the printing application, etc. can be further improved, It is an object to provide a biaxially oriented thermoplastic resin film.

[Means for Solving the Problems] The object of the present invention is achieved by the following biaxially oriented thermoplastic resin film (1) to (4). That is, (1) a film A containing a thermoplastic resin A and particles as a main component is laminated on at least one surface of a film B containing a thermoplastic resin B as a main component, and the thickness of the film A is 0.005 to 3 μm.
m, a biaxially oriented thermoplastic resin in which the average particle size of the particles contained in the film A is 0.1 to 10 times the thickness of the film A, and the content of the particles in the film A is 0.5 to 50% by weight. A biaxially oriented thermoplastic resin film, characterized in that a C layer comprising at least one layer selected from the following (A) to (C) is provided on at least one surface of the film.

(A) Discontinuous film with a height of 10 to 1000Å (b) Low crystalline resin layer with crystallization parameter ΔTcg of 80 ° C or higher (c) Antistatic resin layer with surface resistance of 10 ¹⁴ Ω / □ or less (2 ) A film A containing a thermoplastic resin A and particles as main components is laminated on at least one surface of a film B containing a thermoplastic resin B as a main component, and the average height of surface protrusions of the film A formed by the particles is A biaxially oriented thermoplastic resin film having an average particle size of 1 / 3.5 or more of the particles, wherein at least one surface of the film has a C layer comprising at least one layer selected from the following (a) to (c): A biaxially oriented thermoplastic resin film characterized by being provided.

(A) Discontinuous film with a height of 10 to 1000Å (b) Low crystalline resin layer with crystallization parameter △ Tcg of 80 ° C or higher (c) Antistatic resin layer with surface resistance of 10 ¹⁴ Ω / □ or less (3 ) A film A containing a thermoplastic resin A and particles as main components is laminated on at least one surface of a film B containing a thermoplastic resin B as a main component, and the thickness of the film A is 0.005 to 3 μm.
m, a biaxially oriented thermoplastic resin in which the average particle size of the particles contained in the film A is 0.1 to 10 times the thickness of the film A, and the content of the particles in the film A is 0.5 to 50% by weight. A biaxially oriented thermoplastic resin film, characterized in that a C layer in which the following layers (b) and (c) are laminated is provided on at least one surface of the film.

(B) Low-crystalline resin layer with crystallization parameter ΔTcg of 80 ° C or higher (c) Antistatic resin layer with surface resistance of 10 ¹⁴ Ω / □ or less (4) Thermoplastic resin A and particles as main components Film A having a thermoplastic resin B as a main component is laminated on at least one side, and the average height of the surface projections of the film A formed by the particles is 1 / 3.5 or more of the average particle size of the particles. A biaxially oriented thermoplastic resin film, characterized in that a C layer in which the following layers (b) and (c) are laminated is provided on at least one surface of the biaxially oriented thermoplastic resin film. .

(B) Crystallization parameter ΔTcg is a low crystalline resin layer having a temperature of 80 ° C. or higher (c) An antistatic resin layer having a surface resistance of 10 ¹⁴ Ω / □ or less The thermoplastic resin A in the present invention is polyester, polyolefin, polyamide, Although not particularly limited to polyphenylene sulfide, in particular, polyester,
Among them, at least one structural unit selected from ethylene terephthalate, ethylene α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate, and ethylene 2,6-naphthalate units is the main constituent component. In this case, the shape of the protrusions of high density and uniform height on the film surface is further improved, which is desirable. Further, the thermoplastic resin constituting the present invention is highly desirable because it is easy to form a target projection on the surface of the thermoplastic resin A layer when it is crystalline. Crystallinity here means that it is not so-called amorphous, and quantitatively the cold crystallization temperature Tcc in the crystallization parameter is detected, and the crystallization parameter ΔTcg is 150 ° C or less. is there. Furthermore, when the heat of fusion (change in enthalpy of fusion) measured by a differential scanning calorimeter shows crystallinity of 7.5 cal / g or more, the thermoplastic resin A layer surface protrusion forming performance is excellent, which is highly desirable.
Further, in the case of polyester containing ethylene terephthalate as a main constituent component, the thermoplastic resin A layer surface protrusion forming characteristics are further improved, which is particularly desirable. Two or more kinds of thermoplastic resins may be mixed, or a copolymerized polymer may be used, as long as the present invention is not impaired.

The shape of the particles in the thermoplastic resin A of the present invention is not particularly limited. However, in the case of particles having a particle size ratio (particle major axis / minor axis) in the film of 1.0 to 1.3, particularly spherical particles, ,
This is desirable because it is easy to form film surface protrusions of uniform height.

Further, the particles in the thermoplastic resin A of the present invention are particularly desirable when the single particle index in the film is 0.7 or more, preferably 0.9 or more, because projections having a uniform height can be easily formed at high density.

The type of particles in the thermoplastic resin A of the present invention is not particularly limited, but alumina silicate, silica in which primary particles are agglomerated, internally precipitated particles and the like are not preferable in order to satisfy the above preferable particle characteristics. As the preferred particles, substantially spherical silica particles derived from colloidal silica,
There are particles of cross-linked polymer (for example, cross-linked polystyrene), but especially the temperature at 10% weight loss (measured using a thermogravimetric analyzer Shimadzu TG-30M in nitrogen.
In the case of cross-linked polymer particles having a high degree of cross-linking up to 380 ° C. or higher, the film surface protrusion forming property is further improved, which is particularly desirable. In the case of spherical silica derived from colloidal silica, substantially spherical silica produced by the alkoxide method and having a low sodium content is desirable. However, other particles such as calcium carbonate, titanium dioxide, and alumina can be sufficiently used by appropriately controlling the film thickness and the average particle size.

The thickness of the film layer containing the thermoplastic resin A of the present invention as a main component must be 0.005 to 3 μm, preferably 0.01 to 1 μm, and more preferably 0.03 to 0.5 μm.
If the film thickness is less than the above range, the durability as a laminated film layer cannot be secured, and conversely, if the film thickness is large, it becomes difficult to form surface protrusions of appropriate height at high density due to the relationship with the contained particles. Become.

The size of the particles contained in the film of the thermoplastic resin A is such that the average particle size in the film A containing the particles is 0.1 to 10 times, preferably 0.5 to 5 times the thickness of the film A.
Times, and more preferably 1.1 to 3 times. If the average particle size / film thickness ratio is smaller than the above range, the unevenness of the formed film surface protrusions becomes large, and the scratch resistance and abrasion resistance improvement effects become poor. Is not preferable, and the particle concentration ratio on the film surface described later tends to be lowered, and the scratch resistance and abrasion resistance improving effects are also unfavorable.

The average particle size (diameter) of the particles in the thermoplastic resin A in the film is 0.005 to 3 μm, preferably 0.02 to 0.45.
When the thickness is in the range of μm, the effect of improving scratch resistance and abrasion resistance of the film surface is further improved, which is desirable.

Then, such particles are contained in the film of the thermoplastic resin A in an amount of 0.5 to 50% by weight. Below this,
Since the film surface protrusion formation density is too low, good unevenness transfer characteristics to the magnetic surface cannot be obtained. Conversely, if it is too high,
It is not preferable because the content of the contained particles becomes too high and the laminated film layer itself becomes too brittle.

Further, a thermoplastic resin A formed by the above particles
The average height of the protrusions on the surface of the laminated film layer is 1 / 3.5 or more of the average particle diameter of the particles. The surface protrusion having such an average height can be obtained by appropriately selecting and setting the average particle size of the contained particles with respect to the thickness of the film A from the above range.

That is, the laminated film layer of the thermoplastic resin A in the present invention contains particles having an average particle diameter in the vicinity of the film thickness or larger. In other words, the ultrathin film A contains fine particles having an average particle size in the vicinity of the film thickness or larger. Therefore, the particles can be distributed in the thickness direction of the entire biaxially oriented thermoplastic resin film, substantially concentrated only on the laminated film layer. As a result, the density of the particles in the film A can be easily increased, and the density of the projections on the surface of the film formed by the particles can also be easily increased. Further, since the particles are contained in the film A, the biaxially oriented thermoplastic resin film as a whole,
Since the position is regulated in the thickness direction, and the thickness of the film A and the average particle diameter have the above-described relationship, the height of the surface protrusions formed by the particles becomes extremely uniform. By forming high density and uniform surface protrusions, scratch resistance and abrasion resistance of the film surface are significantly improved.

The film containing the thermoplastic resin A and particles as a main component is laminated on the film containing the thermoplastic resin B as a main component.

The thermoplastic resin B is the same as the above-mentioned thermoplastic resin A, and the thermoplastic resin B and the thermoplastic resin A may be the same kind or different. The film layer of the thermoplastic resin A is laminated on both sides or one side of the film layer of the thermoplastic resin B. In other words, the laminated structure is A / B /
This is the case for A and A / B. (Here, the types of the thermoplastic resins of A and B may be the same or different, and at least one surface must be the A layer.) As the thermoplastic resin B, the crystalline polymer is also used. Is desirable,
In particular, when the crystallinity parameter ΔTcg is in the range of 20 to 100 ° C., the durability of the entire base film as a magnetic recording medium is further improved, which is desirable. Specific examples thereof include polyester, polyamide, polyphenylene sulfide, and polyolefin. In the case of polyester, the durability of the film as a whole is further improved, which is particularly desirable. Also, as polyester,
Ethylene terephthalate, ethylene α, β-bis (2-
A film containing at least one structural unit selected from chlorophenoxy) ethane-4,4'-dicarboxylate and ethylene-2,6-naphthalate units as a main constituent is preferable as a film for a magnetic recording medium. However, other components may be copolymerized within a range that does not impair the present invention and a range that does not impair the desired crystallinity, and preferably within 5 mol%.

Further, the thermoplastic resin B of the present invention may also be blended with another type of polymer within a range that does not impair the object of the present invention, and may also contain an antioxidant, a heat stabilizer, a lubricant, an ultraviolet absorber, and the like. The organic additives may be added to the extent that they are usually added.

The film containing the thermoplastic resin B as a main component need not contain particles, but when this film forms one side of the film surface, the average particle size is 0.007 to 2
.mu.m, especially 0.02-0.45 .mu.m particles 0.001-0.2% by weight,
In particular, when the content is 0.005 to 0.15% by weight, and further 0.005 to 0.12% by weight, not only the coefficient of friction and scratch resistance are good, but also the winding form of the film is good, for example, in the base film application for magnetic recording media. Therefore, it is highly desirable. It is desirable to use the kind of particles contained in the thermoplastic resin A as desired. The types and sizes of the particles contained in the thermoplastic resins A and B may be the same or different.

The thermoplastic resin A containing the particles as described above and the thermoplastic resin B are laminated by coextrusion, molded into a sheet, and then biaxially stretched to obtain a biaxially oriented thermoplastic resin film. Lamination by co-extrusion in the present invention refers to extruding a thermoplastic resin A containing particles and a thermoplastic resin B with different extrusion devices, and laminating them before discharging a laminated sheet from a die. This stack is
It may be performed in a die for forming and discharging into a sheet (for example, a manifold), but since the laminated film layer is extremely thin as described above, it is preferably performed in a polymer tube before being introduced into the die. Particularly, it is particularly preferable that the laminated portion in the polymer tube is formed in a rectangular shape because the laminated portion can be uniformly laminated in the width direction. The molten polymer laminated by the rectangular laminated portion in the polymer tube is widened to a predetermined width in the sheet width direction by the manifold in the die, discharged from the die in a sheet shape, and then biaxially stretched. Therefore, even if the laminated film layer after biaxial orientation is extremely thin, since the particle-containing thermoplastic resin polymer is laminated in a considerable thickness in the rectangular laminated portion in the polymer tube, it is easy and accurate. Can be well laminated.

Further, in the biaxially oriented thermoplastic resin film composed of the thermoplastic resin A and the thermoplastic resin B, the particle concentration ratio of the particles on the surface layer on the laminated film side including the particles is 0.1.
The following is preferred. This surface particle concentration ratio indicates how the particles forming the film surface protrusions are covered with the thin film of the thermoplastic resin A on the film surface as shown in the measuring method described later. The higher the degree of substantially direct exposure, the higher the surface layer particle concentration ratio, and the lower the degree of surface protrusion formation but the higher degree it is covered with the thermoplastic resin A thin film, the lower the surface layer particle concentration ratio. Since the particles forming the protrusions are covered with the thin film of the thermoplastic resin A, even if the particles are densely distributed in the ultrathin laminated film layer, the particles can be distributed in the laminated film layer, and by extension It will be firmly held on the base film layer of the thermoplastic resin B. Therefore, by setting the surface layer particle concentration ratio to the above value or less, the particles are prevented from falling off and the durability of the film surface is maintained high. Such a surface layer particle concentration ratio can be achieved by performing lamination by coextrusion. By the way, by the coating method, it is possible to coat a film similar to the present invention, that is, a base film layer with a resin layer with an extremely thin thickness, and to contain particles in the resin layer, but the surface layer particle concentration The ratio is remarkably high (that is, the degree of direct exposure of the particles to the surface is substantially high), and only the surface of the film of the present invention is extremely brittle.

Then, the above-mentioned C layer is laminated on the film having the laminated constitution of the film layer of the thermoplastic resin A and the film layer of the thermoplastic resin B as described above, and the biaxially oriented thermoplastic resin of the laminated constitution of the present invention is formed. The resin film is completed.

The laminated structure may be any of A / B / C, A / B / A / C, and C / A / B / A / C, but A / B / C is particularly preferable. When the film of the present invention is used as a magnetic recording medium, the laminated structure of the magnetic layer (M) is preferably as follows.

That is, when a discontinuous film having a height of 10 to 1000Å is laminated as a C layer on a laminated constitution film of a thermoplastic resin A and a thermoplastic resin B, M is a C layer and a crystallization parameter Δ is a C layer. When a low crystalline resin layer with a Tcg of 80 ° C or higher is laminated, M has a surface resistance of 10 ¹⁴ Ω as the C layer on the C layer side.
In the case of laminating an antistatic resin layer of / □ or less, M is A or C layer side, and when laminating the low crystalline resin layer and the antistatic resin layer as C layer, M is C On the layer side,
C contains carbon black and / or conductive particles of 5 to 80
When it is contained by weight, M is smaller than the average particle size of the particles contained in the A or C layer side, when the C layer contains substantially no particles, or in the A layer or B layer adjacent to the C layer. When particles having an average particle diameter are contained, M is preferably provided on the A layer side.

The C layer can be laminated in each step in the biaxially oriented thermoplastic resin film manufacturing process. However, since the C layer is an extremely thin layer, it is formed and fixed as the C layer or the film as a whole after the C layer is laminated. It is preferable to prevent the roll or the like from contacting the surface of the C layer by the time. So, for example,
The layer C is preferably laminated before or after the widthwise stretching in the sequential biaxial stretching in which the longitudinal stretching and then the widthwise stretching are performed, or before the simultaneous biaxial stretching. The lamination is industrially preferable such as so-called in-line coating in which coating is performed in the film continuous production process, but may be performed in a separate dedicated process off-line.

The C layer laminated as described above can take various modes depending on the purpose and the use of the film.

First, as the C layer, a discontinuous coating having a height of 10 to 1000Å is laminated. The discontinuous film is made of, for example, a composition mainly containing a water-soluble polymer and a silane coupling agent, and is laminated by, for example, in-line coating. Such lamination of the C layer is particularly suitable for a metal thin film type magnetic recording medium. Since the C layer is extremely thin, even if the C layer is laminated on the A layer side, it can be formed by particles containing the thermoplastic resin A layer. The effect of the surface protrusions of a uniform density and density is substantially maintained as it is, and the durability of the C layer surface (the durability of the magnetic layer surface when the magnetic layer is formed on the C layer surface is further improved by the effect of the C layer lamination). Characteristics), S / when used as a magnetic recording medium
N is greatly improved. The height of the discontinuous coating is 10 to 100
When it is out of the range of 0Å, it becomes difficult to satisfy both the durability of the magnetic layer surface and the S / N as shown in Table 1. However, if it is within the above range, both characteristics should be satisfied. You can

By the way, in the case where there is no layer of the thermoplastic resin A containing particles under specific conditions, that is, in the case of a conventionally known film, even if the C layer as described above is provided, both durability and S / N are improved. Obtaining satisfactory performance is difficult.

Next, when a low crystalline resin having a crystallization parameter ΔTcg of 80 ° C. or higher is laminated as the C layer, the adhesion between the C layer and the magnetic layer for magnetic recording medium application, the ink for printing application, and the like. The adhesiveness of is greatly improved. Preferred low crystalline resins include cyclohexanedimethanol copolymerized polyethylene terephthalate and isophthalic acid copolymerized polyethylene terephthalate. A desirable copolymerization ratio is 0.1 to 40 mol%. When the base film of the present invention has the metal sulfonate of the copolyester constituting the layer C, the aromatic dicarboxylic acid may be 5-sodium sulfoisophthalic acid, 2-sodium sulfoterephthalic acid, 4-sodium sulfo. Isophthalic acid, 4-sodium sulfo-2,6-
Examples thereof include naphthalenedicarboxylic acid, and compounds in which these metals are substituted with other metals such as potassium and lithium. 5-sodium sulfoisophthalic acid is particularly preferable.

The thickness of the C layer in this case is not particularly limited, but is 0.
01 μm or more is desirable.

When an antistatic resin layer having a surface resistance of 10 ¹⁴ Ω / □ or less is laminated as the C layer, the surface protrusions of high density and uniform height formed by the thermoplastic resin A layer-containing particles are A low friction coefficient, and therefore excellent running and handling properties are obtained, while charging during running is favorably suppressed, and extremely good running stability of the film is obtained. As such an antistatic resin, sodium dodecylbenzene sulfonate or the like can be used. Furthermore C
When carbon black and / or conductive particles are contained in the layer, antistatic property can be more positively taken and the running stability can be further improved. Examples of the conductive particles include tin oxide, indium oxide, zinc particles, and tin particles. As a result of the improved running stability, the tape running is stabilized when, for example, a magnetic tape is used, so that the shake of the reproduced image is prevented.

The low crystalline resin layer and the antistatic resin layer may both be laminated as a C layer. The order of lamination is not particularly limited, and the low crystallinity resin layer may be on the surface layer side when the adhesiveness is further required, and the antistatic resin may be on the surface layer side when the antistatic property is further required. In the film thus laminated simultaneously, it is possible to improve both the above-mentioned adhesiveness and antistatic property, and further, the dropout in the magnetic recording medium application becomes good.

Furthermore, in the present invention, the C layer may be a layer which does not substantially contain particles. As described above, particles are concentrated in the adjacent layers of the thermoplastic resin A, and surface protrusions having a high density and a uniform height are formed by the particles. The ultrathin C layer covers the surface protrusions. By doing so, it is possible to reliably keep the above-mentioned surface layer particle concentration ratio much lower. As a result, the abrasion resistance of the film surface is further improved.

The thickness of the C layer in this case is not particularly limited, but is preferably 5 μm or less.

Furthermore, when particles are contained in the C layer, the average particle size of the particles is preferably smaller than the average particle size of the particles containing the adjacent thermoplastic resin A layer or thermoplastic resin B layer. By doing so, the surface protrusions formed by the thermoplastic resin A layer or the thermoplastic resin B layer are basically not blocked by the particles contained in the ultrathin C layer, and rather, For example, a smaller protrusion than C layer-containing particles is placed in the shape line of the surface protrusion formed by A-layer-containing particles, and the friction coefficient can be further reduced. Therefore, scratch resistance and abrasion resistance are further improved.

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

First, the method of incorporating particles into the thermoplastic resin A may be after polymerization, during polymerization, or before polymerization, but a method of kneading a polymer with a vent type twin-screw extruder is a surface of the present invention. It is effective for obtaining a morphological film. In addition, as a method for adjusting the content of particles, a high-concentration master is prepared by the above method, and the content of particles is adjusted by diluting it with a thermoplastic resin that does not substantially contain particles during film formation. The method is effective for obtaining a surface morphological film within the scope of the present invention. Furthermore, the method of adjusting the melt viscosity of the particle high concentration master polymer, the copolymerization component, etc., and keeping the crystallization parameter ΔTcg in the range of 30 to 80 ° C. is a film having a surface morphology within the range of the present invention without stretching breakage. Is effective in obtaining.

Thus, after the pellets A containing particles are sufficiently dried, they are supplied to a known melt extruder and melted at a temperature not lower than the melting point and not higher than the decomposition point of the thermoplastic resin to obtain the thermoplastic resins B and C.
When the layers are used in coextrusion, the C layer is supplied to the laminating apparatus as described above, extruded in a sheet form from a slit die, and cooled and solidified on a casting roll to prepare an unstretched film. That is, these thermoplastic resins are laminated using two or three extruders, a merging block or a die for two or three layers. When the confluent block method is used, the laminated portion is rectangular as described above, and the difference (absolute value) in melt viscosity between the two thermoplastic resins is 0 to 2000 poise,
The range of 0 to 1000 poise is preferably 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.

Next, this multilayer unstretched film is biaxially stretched and biaxially oriented. The method of biaxial stretching may be any of simultaneous biaxial stretching and sequential biaxial stretching, but in the case of sequential biaxial stretching in which the film is stretched in the longitudinal direction and width direction in order to stabilize the film having the surface form within the scope of the present invention. Therefore, it is effective for industrial production without unevenness in the width direction. In the case of sequential biaxial stretching, stretching in the longitudinal direction is divided into three stages, particularly four or more stages, in the range of 40 to 150 ° C., and at a stretching rate of 1000 to 50,000% / min, 3 to.
The method of performing 6 times is effective for obtaining a film having a surface morphology within the scope of the present invention. The stretching temperature and speed in the width direction are
The range of 80 to 170 ° C. and 1000 to 20000% / min is suitable. The stretching ratio is preferably 3 to 10 times. If necessary, it can be further stretched in at least one of the longitudinal direction and the width direction. It is also possible to use a method in which an extremely thin layer containing particles is provided, if necessary, and then stretching is performed at an area stretching ratio (longitudinal direction ratio × width direction ratio) of 9 times or more. Next, this stretched film is heat-treated. The heat treatment conditions in this case are 140 to 280 ° C., preferably 160 to 270 ° C. in a state of relaxation in the width direction, fine stretching, or under constant length.
It is preferable that the temperature is in the range of to 260 ° C. for 0.5 seconds to 60 seconds, but it is preferable to use microwave heating together with the heat treatment because a film having a surface morphology within the range of the present invention can be easily obtained.

And, the layering time of the C layer in the present invention is, theoretically, in the film manufacturing process, within a die or a merging block (for example, a three-layer composite block), after being discharged in a sheet form from the die, before stretching in the longitudinal direction and in the width direction. It is possible to perform coating or melt lamination before stretching, after stretching in the width direction, and further after film formation, offline.
When the C layer is extremely thin, it is preferable that the C layer is laminated either before or after the stretching in the width direction and is not contacted with a roll or the like until the C layer is fixed after the lamination.

The feature of the manufacturing method of the laminated portion of the thermoplastic resins A and B of the above-described film of the present invention is that a very thin layer containing particles is provided by using a high-concentration particle polymer having a specific range of thermal characteristics prepared by a special method. The film is biaxially stretched after the film is formed, and in the film forming step, the film is uniaxially stretched, and then a coating is applied to further stretch the film, or a biaxially stretched film is coated to form a laminated film. The performance of the film is far below, and the film of the present invention is excellent in terms of cost. [Physical property measuring method and effect evaluating method] The characteristic value measuring method and effect evaluating method of the present invention are as follows.

(1) Average particle size of particles The thermoplastic resin is removed from the film by a plasma low temperature ashing method (for example, PR-503 type manufactured by Yamato Scientific Co., Ltd.) to expose the particles. The treatment conditions are selected such that the thermoplastic resin is incinerated but the particles are not damaged. Observe this with an SEM (scanning electron microscope), connect the image of the particles (light and shade of light generated by the particles) to an image analyzer (eg QTM900 manufactured by Cambridge Instruments), and change the observation point to The number average diameter D obtained by the above numerical treatment is used as the treated particle diameter.

D = ΣD _i / N where D _i is the equivalent circle diameter of the particles, and N is the number.

(2) Content of particles A solvent is selected in which the thermoplastic resin is dissolved but not the particles are selected, the particles are centrifuged from the thermoplastic resin, and the ratio (% by weight) to the total weight of the particles is taken as the particle content.
In some cases, the combined use of infrared spectroscopy is also effective.

(3) Glass transition point Tg, cold crystallization temperature Tcc, crystallization parameter ΔTcg, melting point Measured using a DSC (Differential Scanning Calorimeter) II type manufactured by Perxielmer. The DSC measurement conditions are as follows.
That is, 10 mg of a sample is set in a DSC apparatus, melted at a temperature of 300 ° C. for 5 minutes, and then rapidly cooled in liquid nitrogen. The temperature of this quenched sample is raised at 10 ° C./min, and the glass transition point Tg is detected.
The temperature was further raised, and the crystallization exothermic peak temperature from the glass state was set as the cold crystallization temperature Tcc. The temperature was further raised and the melting peak temperature was taken as the melting point. The difference between Tcc and Tg (Tcc-Tg) is defined as the crystallization parameter ΔTcg.

(4) Average height of surface projections A flat surface of the film surface in a two-detector scanning electron microscope [ESM-3200, manufactured by Elionix Co., Ltd.] and a cross-section measuring device [PMS-1, manufactured by Elionix Co., Ltd.] Is sent to an image processing apparatus [IBAS2000, manufactured by Carl Zeiss Co., Ltd.] to scan the height of the projection when the height is 0, and a film surface projection image is reconstructed on the image processing apparatus. Next, the equivalent circle diameter is calculated from the area of each protrusion obtained by binarizing the protrusion portion in this surface protrusion image, and this is made the average diameter of the protrusion. In addition, the highest value among the binarized individual projection portions is set as the height of the projection, and this is obtained for each projection. This measurement was repeated 500 times at different places to determine the number of protrusions, and the average value of the heights of all the measured protrusions was taken as the average height. The magnification of the scanning electron microscope is selected to be a value between 1000 and 8000 times. In some cases, a high-precision optical interference type three-dimensional surface analyzer (WY
Height information obtained using TOPO-3D manufactured by KO, objective lens: 40 to 200 times, use of high resolution camera is effective) may be used by replacing it with the value of the SEM.

(5) Surface layer particle concentration ratio Using the secondary ion mass spectrum (SIMS), the concentration ratio of the highest concentration element of the particles in the film and the carbon element of the thermoplastic resin is set as the measurement concentration, Analyze in the thickness direction. The ratio of the particle concentration A at the outermost surface particle concentration (point at the depth of 0) measured by SIMS and the maximum concentration B obtained by continuing the analysis in the depth direction, A / B was defined as the surface layer particle concentration ratio. The measuring device and conditions are as follows.

Measuring instrument Secondary ion mass spectrometer (SIMS) A-DIDA3000 manufactured by ATOMIKA, West Germany Measuring conditions Primary ion species: O ₂ ⁺ Primary ion accelerating voltage: 12KV Primary ion current: 200nA Raster area: 400μm □ Analysis area: Gate 30% Measurement vacuum degree: 6.0 × 10 ⁹ Torr E-GUN: 0.5KV-3.0A (6) Single particle index The cross section of the film is photographically observed with a transmission electron microscope (TEM) to detect particles. If the observation magnification is set to about 100,000, one particle that cannot be further divided can be observed. When the total 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 a single particle index. The TEM conditions are as follows: 1 field of view area: 2 μm ² measurement is performed by changing the location and measuring 500 fields of view.

・ Device: JEM-1200EX manufactured by JEOL ・ Observation magnification: 100000 times ・ Section thickness: Approximately 1000 Å (7) Particle size ratio In the measurement of (1) above, the average value of the major axis / the average value of the minor axis of each particle. Is the ratio of

 That is, it is calculated by the following formula.

Major axis = ΣD1 _i / N long diameter short diameter _{= ΣD2 i / N D1 i,} D2 i each individual particle (maximum diameter), short diameter (the shortest diameter), N is the total number.

(8) Thickness of the thermoplastic resin A layer in the laminated film Using a secondary ion mass spectrometer (SIMS), the element of the thermoplastic resin and the element caused by the highest concentration of the particles in the film are used. The concentration ratio of carbon element (M ⁺ / C ⁺ ) is defined as the particle concentration,
Analysis in the depth (thickness) direction from the surface of the thermoplastic resin A layer is performed. In the surface layer, the particle concentration is low due to the interface of the surface, and the particle concentration increases as it goes from the surface. In the case of the film of the present invention, the particle concentration once reaching the maximum value at the depth [I] starts to decrease again. Based on this concentration distribution curve, the depth [II] (where I
The layer thickness was defined as I> I). The conditions are the same as in measurement method (5).

If the particles contained in the film most are organic polymer particles, it is difficult to measure with SIMS, so while etching from the surface, XPS (X-ray photoelectron spectroscopy), IR
(Infrared spectroscopy) or confocal microscope,
The depth profile of the particle concentration may be measured and the laminated thickness may be obtained by the same method as described above.

Further, instead of the depth profile of the particle concentration described above, the lamination thickness of the thermoplastic resin A may be obtained by observing a cross section of a film or a thin film level measuring device.

(9) Height of discontinuous film In a surface roughness curve obtained by measuring with a high precision thin film step measuring instrument ET-10 manufactured by Kosaka Laboratory, with a cutoff value of 0.08 mm and a vertical magnification of 500,000 times, The distance between the average height of the mountain and the average depth of the valley was defined as the height of the film.

(10) Surface resistance of film The film to be measured is placed on a thick rubber sheet with the measurement surface facing up, and the length of one side of the square is formed so as to form two opposite sides of the square. Place two rectangular brass electrodes with a width of 1/10 of the length and a smooth polished bottom surface, and apply a pressure of 0.2 Kg / cm ² from above the electrodes. Measure the electrical resistance of. At this time, the size of the electrode is appropriately selected according to the size of the film to be measured. The unit at this time is represented by Ω / □.

(11) Scratch resistance A film slit into a 1/2 inch wide tape is run on a guide pin (surface roughness: Ra 100 nm) using a tape running tester (running speed 1000 m / Minutes, 10 passes, winding angle: 60 °, running tension: 70g). At this time, the scratch in the film is observed under a microscope and the width is 2.5μ.
Less than 2 scratches per tape width of m or more are excellent, 2 or more 10
Less than this number was judged to be good, and 10 or more were judged to be defective. Good is desirable, but good is practically usable.

(12) Scraping resistance The film is slit into a tape with a width of 1/2 inch, a single blade is pressed vertically, and the product is run for 20 cm while being pushed 0.5 mm (running tension: 500 g, running speed: 6.7 cm /
Seconds). At this time, the height of the scraped material on the surface of the film attached to the tip of the single-edged blade was read with a microscope and used as the scraped amount (unit: μ
m). At least on one side, it was determined that the abrasion resistance was good when the amount of powder abrasion was 10 μm or less, and the abrasion resistance was poor when the amount of powder abrasion exceeded 10 μm. The scraping amount of 10 μm is a critical point for determining whether or not the film surface is scraped in a working process such as a printing process or a calendering process, which causes a trouble in process or product performance.

(13) Chroma S / N ratio (C-S / N) Measured using a household VHS system VTR and a Shibasoku 925C type color video noise meter.

In addition, as a standard, the one having the lowest C-S / N among the respective experimental levels is indicated as 0 dB and is relatively displayed.

(14) Durability of magnetic surface The durability of the magnetic tape was evaluated by measuring the decrease in S / N after 1000 passes on a household VTR and 1,000 times. S / N reduction of less than 1 dB was regarded as good durability.

(15) Adhesiveness with magnetic layer Commercially available polyester adhesive tape (19 mm width) on the magnetic coating film
Paste to a length of 30mm and peel it off at once. The total light transmittance of the part where the coating film was peeled off was measured with a haze meter SEP-H-2 manufactured by Nippon Seimitsu Kogaku (JIS-K-7105), and the remaining amount of the coating film was determined by the following formula to determine the adhesiveness.

Remaining amount of magnetic coating peeling D = (T ₀ −T ₁ ) / T ₀ × 100 (%) where T ₀ : total light transmittance (%) before application of magnetic coating (raw) T ₁ : magnetic Value of total light transmittance (%) D in the peeled-off portion of the coating film Judgment less than 20% × Adhesion failure does not reach the object of the invention.

20 or more and less than 40% △ The object of the present invention is not reached due to poor adhesion.

40 or more and less than 60% ○ Good adhesiveness and the object range of the present invention 60% or more ◎ Adhesiveness is particularly good and the object range of the present invention (16) Adhesiveness of ink Ink for cellophane (Toyo Ink Co., Ltd.'CC- ST "white) is applied using a metalling bar to a solid content of about 3 g / m ² , dried with hot air for 1 minute at 60 ° C, and a commercially available Nichiban cellophane adhesive tape is applied to the printed surface. The total area of ink remaining after 90 ° peeling was evaluated.

 The evaluation criteria are as follows.

Remaining area (%) Adhesiveness evaluation 90% or more and less than 100% ○ 75% or more and less than 90% △ Less than 75% × ○, △ are sufficient as practical adhesives.

(17) Antistatic film A slit-shaped film with a width of 1/2 inch was used to guide a guide pin (surface roughness: SFT-700, manufactured by Yokohama System Research Co., Ltd.). 0.2S) running (running speed 3.3cm / sec, number of round trips 100 passes, winding angle 180 °), initial friction coefficient μk ₀ and round trip 100
The maximum friction coefficient μkmax during the traveling was determined by the following formula.

μk = 0.733log (T ₂ / T ₁ ) where T ₁ is the inlet tension and T ₂ is the outlet tension. The rise μkmax-μk ₀ the coefficient of friction due to frictional electrification was determined.

μkmax-μk ₀ is the case of 0.02 or less antistatic: good, if exceeding 0.02 antistatic property: were determined to be defective.
This value of μk max −μ k ₀ : 0.02 is a value for determining whether or not good tape running stability can be obtained without increasing the friction coefficient due to charging when a magnetic tape is used.

[Examples] The present invention will be described based on examples.

Examples 1 to 8 and Comparative Examples 1 to 8 Ethylene glycol slurries containing crosslinked polystyrene particles having different average particle sizes and spherical silica particles derived from colloidal silica were prepared, and the ethylene glycol slurries were heat-treated at 190 ° C. for 1.5 hours. After that, after transesterification with dimethyl terephthalate, polycondensation was carried out to obtain 0.3
Polyethylene terephthalate (up to 55% by weight)
Abbreviated as PET). A thermoplastic resin A is prepared using these pellets, and by a conventional method,
PET containing 0.3% by weight of spherical silica particles having a diameter of 0.03 μm was produced and designated as a thermoplastic resin B. Each of these polymers was dried under reduced pressure (3 Torr) at 180 ° C. for 3 hours. The thermoplastic resin A is supplied to the extruder 1 and melted at 285 ° C., the thermoplastic resin B is further supplied to the extruder 2 and melted at 280 ° C., and these polymers are joined by a joining block having a rectangular laminated portion. The layers were laminated, wound around a casting drum having a surface temperature of 30 ° C. by using the electrostatically applied casting method, and cooled and solidified to form a three-layer unstretched film having two layers or a thermoplastic resin A layer on both sides. At this time, the discharge amount of each extruder was adjusted to adjust the total thickness and the thickness of the thermoplastic resin A layer. (However, Comparative Example 7 is an A layer single layer, and Comparative Example 8 is a B layer single layer). 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 the difference in peripheral speed between each pair of rolls. Each of the uniaxially stretched films was coated in-line so as to have the structure of layer C shown in Table 2, and the coated uniaxially stretched film was stretched 4.0 times in the width direction at 100 ° C. at a stretching rate of 2000% / min using a stenter. Stretched and heat-treated in the longitudinal direction at a tension of 2 kg / m at 200 ° C for 5 seconds to give a total thickness of 15 µm and a thermoplastic resin A layer thickness of 0.03 to 4 µm.
A biaxially oriented laminated film of m was obtained. The parameters of the present invention for these films are shown in Table 2.

Examples 9 to 16 and Comparative Examples 9 to 13 Similar to the above Examples, in Examples 9 to 16, a three-layer laminated unstretched film in which different polymers were laminated on both surfaces of the B layer, and Comparative Example 11 were used. Nos. 13 to 13 used two extruders to obtain a two-layer laminated unstretched film, and Comparative Examples 9 to 10 used three extruders to obtain a three-layer unstretched film. These unstretched films were stretched 4.2 times in the longitudinal direction at a temperature of 80 ° C. This uniaxially stretched film was stretched 4.5 times in the width direction at 105 ° C. at a stretching rate of 2000% / min using a stenter, and heat-treated at 190 ° C. for 5 seconds under a constant length to obtain a biaxially oriented film. The parameters of the present invention for these films are the third and fourth.
As shown in the table.

The scratch resistance and abrasion resistance of the obtained film on the C layer side were evaluated, as well as the adhesion to the magnetic layer, the ink adhesion, and the antistatic property. A magnetic layer was applied to the surface of the layer C of the obtained film to prepare a tape, which was wound under normal winding tension to obtain a magnetic tape. The durability and S / N of the magnetic surface of this magnetic tape were measured. As a result, when the parameter of the present invention is within the range, each characteristic has the second value.
Good values were shown as shown in Tables 4 to 4, but in the other cases, excellent films which could satisfy all the respective characteristics were not obtained.

[Effects of the Invention] As described above, when the biaxially oriented thermoplastic resin film of the present invention is used, it is laminated by the particles contained in the thermoplastic resin A layer of the laminated film comprising the thermoplastic resin A and the thermoplastic resin B. Since high density and uniform projections are formed on the surface of the film, and the C layer is further laminated on the laminated film to further improve the surface characteristics according to the use,
It is possible to greatly improve the adhesiveness with the magnetic layer, the durability of the magnetic surface, the S / N, the antistatic property in various applications, the adhesiveness of the ink in the printing application, etc. in the magnetic recording medium application.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location C08L 101/00 C08L 101/00 (56) References JP-A-1-198350 (JP, A) Special features Kaihei 1-176556 (JP, A) JP 48-17865 (JP, A) JP 58-155940 (JP, A) JP 58-62826 (JP, A) JP 62-108053 ( JP, A) JP 58-38158 (JP, A) JP 58-65658 (JP, A) JP 58-153640 (JP, A) JP 3-207651 (JP, A) JP Flat 3-207650 (JP, A) European patent application publication 347646 (EP, A)

Claims (8)

(57) [Claims] 1. A film A containing a thermoplastic resin A and particles as a main component is laminated on at least one surface of a film B containing a thermoplastic resin B as a main component, and the thickness of the film A is 0.005 to.
3 μm, the average particle size of the particles contained in the film A is 0.1 to 10 times the thickness of the film A, and the film A of the particles is
A biaxially oriented thermoplastic resin film having a content of 0.5 to 50% by weight, wherein the film has at least one surface,
A biaxially oriented thermoplastic resin film provided with a C layer comprising at least one layer selected from the following (A) to (C). (A) Discontinuous film with a height of 10 to 1000Å (b) Low crystalline resin layer with crystallization parameter ΔTcg of 80 ° C or higher (c) Antistatic resin layer with surface resistance of 10 ¹⁴ Ω / □ or less 2. A film A containing a thermoplastic resin A and particles as a main component is laminated on at least one side of a film B containing a thermoplastic resin B as a main component, and a surface projection of the film A formed by the particles is formed. Average height is 1 / of the average particle size of the particles
A biaxially oriented thermoplastic resin film having a size of 3.5 or more, characterized in that at least one surface of the film is provided with a C layer comprising at least one layer selected from the following (a) to (c): Oriented thermoplastic resin film. (A) Discontinuous film with a height of 10 to 1000Å (b) Low crystalline resin layer with crystallization parameter ΔTcg of 80 ° C or higher (c) Antistatic resin layer with surface resistance of 10 ¹⁴ Ω / □ or less 3. A film A containing a thermoplastic resin A and particles as a main component is laminated on at least one side of a film B containing a thermoplastic resin B as a main component, and the thickness of the film A is 0.005 to.
3 μm, the average particle size of the particles contained in the film A is 0.1 to 10 times the thickness of the film A, and the film A of the particles is
A biaxially oriented thermoplastic resin film having a content of 0.5 to 50% by weight, wherein the film has at least one surface,
A biaxially oriented thermoplastic resin film provided with a C layer in which the following layers (B) and (C) are laminated. (B) Low crystalline resin layer with crystallization parameter ΔTcg of 80 ° C or higher (c) Antistatic resin layer with surface resistance of 10 ¹⁴ Ω / □ or less 4. A film A containing a thermoplastic resin A and particles as a main component is laminated on at least one side of a film B containing a thermoplastic resin B as a main component, and a surface projection of the film A formed by the particles is formed. Average height is 1 / of the average particle size of the particles
A biaxially oriented thermoplastic resin film of 3.5 or more, characterized in that a C layer in which the following layers (b) and (c) are laminated is provided on at least one surface of the film. Plastic resin film. (B) Low crystalline resin layer with crystallization parameter ΔTcg of 80 ° C or higher (c) Antistatic resin layer with surface resistance of 10 ¹⁴ Ω / □ or less 5. The C layer (c) contains an antistatic resin layer having a surface resistance of 10 ¹⁴ Ω / □ or less, and the antistatic resin layer contains carbon black and / or other conductive particles in an amount of 5 to 5. The biaxially oriented thermoplastic resin film according to claim 1 or 2, containing 80% by weight. 6. The biaxially oriented thermoplastic resin film according to claim 3, wherein the antistatic resin layer contains 5 to 80% by weight of carbon black and / or other conductive particles. 7. The biaxially oriented thermoplastic resin film according to claim 1, wherein the C layer is substantially free of particles. 8. A film A in which the C layer is adjacent to the C layer.
5. Particles having an average particle size smaller than the average particle size of the particles contained in the layer or the film B layer.
The biaxially oriented thermoplastic resin film according to any one of 1.