JPH09323385A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film which has superior properties such as take-up, easy slippage and handling and also, other properties such as electro magnetic conversion, dropout, traveling of a magnetic layer and durability. SOLUTION: This laminated film consists of a coated layer B containing a particle B of a core shell structure comprising a more pliable outer part than an inner part with an average grain size (dB) of 5-100nm and a volumetric shape factor of 0.1-π/6, and water resin, laminated on, at least one of the faces of a thermoplastic resin layer A which substantially does not contain an inert particle. In addition, the average grain size (dB) (nm) of the particle B, the grain size (dcB) (nm) of the core part of the particle B and the layer thickness (tB) (nm) of the coated layer B satisfy formulae 1.01<=dB/dcB<=3.0, 0.05<=tB/ dcB<=0.8, simultaneously. Further, the frequency of a surface protrusion consisting of the particle B is (1×10<6> )-(1×10<8> )pcs/mm<2> , and the frequency of the protrusion which is formed of the macroaggregate of the particle B and is at least 0.5μm high is 50pcs/cm<2> or less.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laminated film. Specifically, it is suitable for use as a magnetic recording medium having excellent winding properties, slipperiness, handling properties, etc., and excellent electromagnetic conversion characteristics, dropouts, running properties of a magnetic layer, and durability, particularly a high-density magnetic recording medium. And a thermoplastic resin laminated film.

[0002]

2. Description of the Related Art In recent years, remarkable progress has been made in increasing the density of magnetic recording. For example, a ferromagnetic metal thin film in which a ferromagnetic metal thin film is formed on a nonmagnetic support by a physical deposition method such as vacuum evaporation or sputtering or a plating method. Development and commercialization of magnetic recording media and thin-layer coating type magnetic recording media in which needle-like magnetic powder such as metal powder or iron oxide powder is applied to a thickness of 2 μm or less are progressing.

Examples of the former include, for example, Co-deposited tape (Japanese Patent Application Laid-Open No. 54-147010), Co-Cr
Perpendicular magnetic recording medium made of an alloy (Japanese Patent Laid-Open No. 52-1347)
No. 06 publication) is known. As an example of the latter, for example, high-density magnetic recording using an ultra-thin layer coating type medium (IEICE Technical Report MR94-78 (1995-02)) is known.

Conventional coating type magnetic recording media (magnetic recording media obtained by mixing a magnetic powder in an organic polymer binder and coating on a non-magnetic support) have a low recording density and a long recording wavelength. While the thickness of the magnetic layer is as thick as about 2 μm or more, the metal thin film formed by thin film forming means such as vacuum deposition, sputtering or ion plating is very thin, not more than 0.2 μm, and extremely thin. In the case of a layer coating type medium, the non-magnetic underlayer
It is very thin with a thickness of 3 μm.

For this reason, in the high-density magnetic recording medium described above, the surface condition of the non-magnetic support greatly affects the surface properties of the magnetic recording layer. The surface state of the magnetic support is directly expressed as irregularities on the surface of the magnetic recording layer, which causes noise in the reproduced signal. Therefore, it is desirable that the surface of the non-magnetic support be as smooth as possible.

On the other hand, from the viewpoint of handling such as film forming of the base film, conveyance / scratching in the working process, winding, and unwinding, if the film surface is too smooth, the slipperiness between the films will deteriorate, The blocking phenomenon occurs, the shape when rolled into a roll (roll formation) deteriorates, the product yield decreases, and the product manufacturing cost increases. Therefore, from the viewpoint of manufacturing cost, it is desirable that the surface of the support be as rough as possible.

As described above, the surface of the non-magnetic support is required to be smooth from the viewpoint of electromagnetic conversion characteristics, and it is required to be rough from the viewpoint of handleability and film cost.

Further, in the case of a vapor-deposited metal thin film type magnetic recording medium, a serious problem in actual use is the running property of the metal thin film surface. In the case of a coating type magnetic recording medium in which magnetic powder is mixed in an organic polymer bander and coated on a base film, a lubricant may be dispersed in the binder to improve the running property of the magnetic surface. However, in the case of a vapor-deposited metal thin film type magnetic recording medium, such measures cannot be taken, and it is very difficult to keep the running stability stably, and especially the running performance under high temperature and high humidity conditions is poor. There are problems such as.

Therefore, in order to inexpensively supply a high-density base film for high-density recording media, it is necessary to satisfy the above-mentioned contradictory properties at the same time.

As a concrete measure for this, a method of applying a specific coating agent to the surface of the film to form a discontinuous film (Japanese Patent Publication No. 3-80410, JP-A-60-180839).
No., JP-A-60-180838, JP-A-60-180
No. 837, JP-A-56-16937, JP-A-58-6
8223), and a method for forming a continuous film having fine protrusions (JP-A-5-194772, JP-A-5-210).
No. 833), a method of making the front and back different by a technique such as coextrusion (Japanese Patent Laid-Open No. 2-214657, Japanese Patent Publication No. 7-802).
82), a method using the above + or a combination of + (Japanese Patent Laid-Open No. 3-73409), and the like.

[0011]

However, in the conventional method for forming a discontinuous film or a continuous film having fine protrusions, although problems such as film-to-film slippage and blocking can be solved, There is a problem that it is difficult to uniformly disperse fine inert particles therein, and coarse projections due to agglomerated particles are easily generated, so that electromagnetic conversion characteristics are deteriorated and the quality as a magnetic tape is not stable. Agglomerated particles are more likely to be scraped off by contact with various guide rolls in the film forming process than monodispersed particles, and adhere to and accumulate on the base film to form protrusions, which can cause dropout when used as a magnetic tape. There is also. In addition, even if it has excellent dispersibility in the film when viewed from a fine field of view, the presence of coarse agglomerated particles when viewed from a macro field causes a problem such as an increase in dropout when used as a magnetic tape. .

Generally, since inorganic particles have high hardness and are hard to be deformed, they are excellent in the cleaning property of the magnetic head, and it is easy to produce fine particles of various sizes. A tendency is likely to occur. On the other hand, although the organic particles have excellent affinity with the polymer, the hardness is lower than that of the inorganic particles, and the entire particle is deformed by heat or mechanical friction. There is a problem of deterioration.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art and to be excellent in sharpness and winding property in the film forming process, and to be used as a vapor-deposited metal thin film type magnetic recording medium or an ultrathin layer coating type magnetic recording medium. It is intended to provide a laminated film having excellent electromagnetic conversion characteristics, dropout characteristics, and running durability in such a case.

[0014]

According to the present invention, firstly, an aqueous resin and an average particle size are provided on at least one surface of a thermoplastic resin layer A which is substantially free of inert particles. d _B is 5 to 100 nm, a volume shape factor of 0.1~π
/ 6 in which the outside from the inside is a laminated film obtained by laminating a film layer B containing particles B of a flexible core-shell structure, an average particle diameter d _B (nm) of the particle B, the particle of the core portion of the particles B Diameter dc _B (nm) and layer thickness t _B (nm) of coating layer B
Satisfy the following expressions (1) and (2) at the same time, the frequency of surface protrusions by the particles B of the coating layer B is 1 × 10 ⁶ to 1 × 10 ⁸ particles / mm ² , and the macroaggregates of the particles B are According to the laminated film, the frequency of protrusions having a height of 0.5 μm or more is 50 / cm ² or less.

[0015]

[Formula 5] 1.01 ≦ d _B / dc _B ≦ 3.0 (1)

[0016]

## EQU6 ## 0.05 ≦ t _B / dc _B ≦ 0.8 (2)

Examples of the thermoplastic resin in the present invention include polyester resin, polyamide resin, polyimide resin, polyether resin, polycarbonate resin, polyvinyl resin, polyolefin resin and the like. Of these, polyester-based resins and aromatic polyesters are preferred.

As the aromatic polyester, polyethylene terephthalate, polyethylene isophthalate,
Preferably, polytetramethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate and the like can be preferably exemplified. Of these, polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate are preferred.

The above polyester may be a homopolyester or a copolyester. In the case of a copolyester, as a copolymerization component of polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate, for example, diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylene glycol, 1,4-cyclohexanedimethanol Diol components such as adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid (for polyethylene-2,6-naphthalenedicarboxylate), 2,6-naphthalenedicarboxylic acid (for polyethylene terephthalate), Other dicarboxylic acid components such as 5-sodium sulfoisophthalic acid, and oxycarboxylic acid components such as p-oxyethoxybenzoic acid are exemplified. Incidentally, the amount of the copolymer component is 20 mol% or less,
It is preferably at most 0 mol%. Further, a trifunctional or higher polyfunctional compound such as trimellitic acid or pyromellitic acid can be copolymerized. In this case, the polymer is preferably copolymerized in a substantially linear amount, for example, 2 mol% or less.

In the present invention, it is necessary that the thermoplastic resin layer A contains substantially no particles. Here, the term "substantially free of particles" does not include externally added particles or internally precipitated particles that form projections on the film surface,
This means that a very small amount of particles which do not substantially exert a lubricant action, which may be caused by a catalyst required for polyester polymerization, may be contained. For example, other additives such as an antioxidant, a heat stabilizer, and an antistatic agent (excluding particles that form surface protrusions) can be contained if necessary.

The aqueous resin constituting the coating layer B in the present invention means a water-soluble organic resin and a water-dispersed organic resin, and is an aqueous alkyd resin, phenol resin, epoxy resin, amino resin, polyurethane resin, vinyl acetate. Examples thereof include resins and vinyl chloride-vinyl acetate copolymers, but from the viewpoints of adhesion to the thermoplastic resin layer A, retention of protrusions, slipperiness, and the like, water-based acrylic resin, polyester resin, acrylic- Polyester resins are preferred. These aqueous resins may be a homopolymer or a copolymer, or may be a mixture.

The above-mentioned aqueous acrylic resin is, for example, an acrylic ester (as the alcohol residue, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group). Group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group, etc.); methacrylic acid ester (alcohol residue is the same as above); 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate Hydroxy-containing monomers such as 2-hydroxypropyl methacrylate; acrylamide, methacrylamide, N-methylmethacrylamide, N-methylacrylamide, N-
Amide group-containing monomers such as methylol acrylamide, N-methylol methacrylamide, N, N-dimethylol acrylamide, N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide, N-phenylacrylamide; N, N-diethylaminoethyl acrylate; Amino group-containing monomers such as N, N-diethylaminoethyl methacrylate; epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether; styrene sulfonic acid, vinyl sulfonic acid, and salts thereof (eg, sodium salt, potassium Such as crotonic acid, itaconic acid, acrylic acid, maleic acid, fumaric acid, and the like. (E.g., a monomer containing a carboxyl group or a salt thereof such as a sodium salt, a potassium salt, or an ammonium salt); a monomer containing an anhydride such as maleic anhydride or itaconic anhydride; other vinyl isocyanate, allyl isocyanate, styrene, Vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester,
Alkyl fumaric acid monoester, acrylonitrile,
(Meth) acrylic monomers such as acrylic acid derivatives and methacrylic acid derivatives, which are made from a combination of monomers such as methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate and vinyl chloride Is preferably contained in an amount of 50 mol% or more, particularly preferably a component containing a methyl methacrylate component.

Such an aqueous acrylic resin can be self-crosslinked with a functional group in the molecule, or can be crosslinked with a crosslinking agent such as a melamine resin or an epoxy compound.

Examples of the acid component constituting the aqueous polyester resin include terephthalic acid, isophthalic acid,
Phthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,
6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, succinic acid, 5-sodium sulfoisophthalic acid, 2-potassium sulfoterephthalic acid, trimellitic acid, trimesic acid, anhydrous Examples thereof include polyvalent carboxylic acids such as trimellitic acid, phthalic anhydride, p-hydroxybenzoic acid and trimellitic acid monopotassium salt. Examples of the hydroxy compound component include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p- Xylylene glycol, bisphenol A ethylene oxide adduct, diethylene glycol, triethylene glycol, polyethylene oxide glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropanoate Polyhydric hydroxy compounds such as A polyester resin can be prepared from these compounds by a conventional method. From the viewpoint of preparing an aqueous paint, it is preferable to use an aqueous polyester resin containing a 5-sodium sulfoisophthalic acid component or a carboxylate group. Such a polyester resin can be of a self-crosslinking type having a functional group in the molecule, or can be crosslinked using a curing agent such as a melamine resin or an epoxy resin.

Furthermore, the water-based acrylic-polyester resin is used in the sense of including an acrylic-modified polyester resin and a polyester-modified acrylic resin, and the acrylic resin component and the polyester resin component are bonded to each other. Graft type, block type, etc. are included. Acrylic-polyester resins, for example, add a radical initiator to both ends of the polyester resin to cause polymerization of the acrylic monomer, or add a radical initiator to the side chain of the polyester resin to polymerize the acrylic monomer. Alternatively, it can be produced by adding a hydroxyl group to the side chain of the acrylic resin and reacting it with a polyester having an isocyanate group or a carboxyl group at a terminal to obtain a comb polymer.

In the present invention, particles having a softer outside than inside (hereinafter referred to as shell core particles) B are particles having a multi-layer structure in which the inside and outside are composed of substances having different properties. In this case, the multilayer means two or more layers, and the property may be continuously changed in the radial direction. The outside (hereinafter referred to as the shell part) of the particles has a function of reacting with the film base after being applied on the film, or reacting, melting, softening or deforming by performing heat treatment to fix the film to the film base. It is considered that (hereinafter, referred to as a core portion) has a function as a so-called particle, which, together with the shell portion, imparts appropriate slipperiness to the film and optimal spacing with the magnetic head. From the viewpoint of function sharing of each of the shell and core parts, the shell part is required to have excellent affinity with the film base and have appropriate physical, chemical and thermal properties at the film-forming heat treatment temperature. The core portion is required not to be deformed by mechanical friction or the like and to have a hardness relatively large with respect to the shell portion or the base layer film.

As the material of the core portion of the shell core particles B, polystyrene, polystyrene-divinylbenzene, polymethyl methacrylate, methyl methacrylate copolymer, cross-linked methyl methacrylate, polytetrafluoroethylene, polyvinylidene fluoride,
Organic materials such as polyacrylonitrile and benzoguanamine resin, silica, alumina, titanium dioxide, kaolin,
Any of inorganic materials such as talc, graphite, calcium carbonate, feldspar, molybdenum disulfide, carbon black, and barium sulfate may be used.

The material of the shell portion is generally preferably a thermoplastic resin, particularly preferably an acrylic resin or a polyester resin. Further, in order to enhance the affinity with the film base portion, the film base portion may be added at any ratio in the molecule. It is preferable to introduce a functional group having reactivity or affinity with, specifically, a carboxyl group, a hydroxyl group, a glycidyl group, an amide group, an epoxy group, an isocyanate group or the like. These functional groups may be used alone or in combination of two or more depending on the case. Further, the glass transition temperature (hereinafter referred to as Tg) of the shell portion is preferably 80 ° C. or less, more preferably 20 ° C.
The following is good. If the Tg exceeds 80 ° C., the shell core particles fall off from the film. By using the polymer having such a composition in the shell portion, excellent abrasion resistance can be exhibited.

The ratio (d _B / dc _B ) of the particle size d _B (nm) of the shell core particles B and the particle size dc _B (nm) of the core part is
It is 1.01 to 3.0, preferably 1.02 to 2.0, and more preferably 1.04 to 1.5. This ratio (d _B / d
When c _B ) is more than 3.0, the property like organic particles consisting only of the material of the shell portion having no multilayer structure is strongly exerted, and the deformation due to heat or mechanical friction increases. On the other hand, when it is less than 1.01, the property as an inorganic particle is strengthened, the sticking property to the film is lowered, the falling of the particle tends to increase, and the agglomeration rate tends to increase. In either case, the workability of the film and the performance of the magnetic tape are likely to be adversely affected, which is not preferable.

The volume shape factor (f) of the shell core particle B defined by the following formula is 0.1 to π / 6.

[0031]

F = V / d _B ³ Here, V represents the volume of the shell-core particles, and d _B represents the average particle size of the particles.

The volume shape factor f is preferably 0.3 to π / 6, more preferably 0.4 to π / 6 substantially spherical or rugby ball-like elliptical sphere. If f is smaller than 0.1, for example, flaky particles, the magnetic properties of the thin-film magnetic layer deteriorate.

The shell core particles B have an average particle size of 5 to 100.
nm, preferably 10 to 50 nm. Further, those having a uniform particle size distribution are preferable. When the average particle size is less than 5 nm, the slip property and the abrasion resistance are deteriorated, and a blocking phenomenon occurs when wound in a roll shape. On the other hand, if the average particle size exceeds 100 nm, the particles will fall off and the abrasion resistance will deteriorate. Further, the spacing with the magnetic head is increased, and it is difficult to provide a high-density magnetic recording medium.

The aggregation ratio of the shell core particles B in the coating layer B is preferably 10% or less, more preferably 5% or less. When the agglomeration rate exceeds 10%, the properties of the particle aggregates as abnormal projections become remarkable, and the particles are liable to fall off, which tends to adversely affect the performance as a magnetic tape.

The frequency of protrusions having a height of 0.5 μm or more due to macro-aggregates of the shell core particles B is 50 / cm ² or less, preferably 25 / cm ² or less. When the projection frequency due to the macro-aggregates exceeds 50 / cm ² , dropout becomes remarkable, which is a practical problem.

The shell core particles B are contained in the coating layer B in an amount such that the surface protrusion frequency of the coating layer B is 1 × 10 ⁶ to 1 × 10 ⁸ particles / mm ² . This surface protrusion frequency is 1 x 10
^If it is less than ⁶ pieces / mm ² , the running durability when used as a magnetic recording medium is insufficient. On the other hand, when it exceeds 1 × 10 ⁸ pieces / mm ² , the electromagnetic conversion characteristics are adversely affected. The surface protrusion frequency is more preferably 2 × 10 ^{6 to} 5 × 10 ⁷ pieces / mm ² , and further preferably 3.0 × 10 ^{6 to} 3.0 × 10 ⁷ pieces / mm ² .

Ratio (d _B / dc _B ) of the layer thickness t _B (nm) of the coating layer B and the particle size dc _B of the core portion of the shell core particle B.
Is 0.05 to 0.8, preferably 0.08 to 0.6,
More preferably, it is 0.1 to 0.5. This ratio (d _B /
When dc _B ) exceeds 0.8, the projection forming action of the shell core particles B is reduced, and running durability when used as a magnetic recording medium is insufficient. On the other hand, when it is less than 0.05, particles are scraped off due to contact with various guide rolls in the film forming process, and running durability is insufficient, or the scraped particles are deposited and deposited on the film to increase dropout. Or cause.

The shell core particles B can be produced, for example, in a system in which particles of the core portion are present, by emulsion-polymerizing the polymerizable monomer of the shell portion and coating the surface of the particles of the core portion. It is not limited by the manufacturing method of.

The coating layer B in the present invention is formed by applying a coating solution containing the above-mentioned shell core particles and an aqueous resin, preferably an aqueous coating solution, to at least one surface of the thermoplastic resin layer A, and drying the coating solution. The solid concentration of the liquid is 0.2-
10% by weight, further 0.5 to 5% by weight, especially 0.7 to
It is preferably 3% by weight. If desired, other components such as a surfactant, a stabilizer, a dispersant, a UV absorber, a thickener, etc. may be added to this coating liquid, preferably an aqueous coating liquid, as long as the effects of the present invention are not impaired. It can be added.

It is preferable to apply the thermoplastic resin film before the final stretching, and to stretch the film in at least uniaxial direction after the coating. Before or during this stretching, the coating film is dried. Among them, the coating is preferably performed on an unstretched thermoplastic resin film or a longitudinally (uniaxially) stretched thermoplastic resin film. The application method is not particularly limited, but examples include a roll coating method and a die coating method.

By using the shell core particles B in the present invention, the particle agglomeration rate and the frequency of macroaggregates in the coating layer B are significantly improved as compared with the case of using the conventional inorganic or organic particles. However, the reason for this may be an increase in repulsive force between particles due to a change in potential on the particle surface, a change in stable pH region, and the like.

An atomic force microscope (AF) of the surface of the coating layer B is used.
The surface roughness ARa _B (nm) according to M) is 0.3 to 5.0.
nm, further 0.5-4.0 nm, especially 0.7-2.5
and the 10-point average roughness ARz _B (nm) is 1
0-100 nm, more preferably 15-70 nm, especially 20-4
It is preferably 0 nm. This ARz _B is 5.0n
If it exceeds m, or if ARz _B exceeds 100 nm, the electromagnetic conversion characteristics are deteriorated, especially when a metal thin film type magnetic recording medium is used. On the other hand, when ARz _B is less than 0.3 nm, or when ARz _B is less than 10 nm,
The slipperiness is extremely deteriorated so that the running durability is insufficient, or the tape sticks to the magnetic head to cause squeaking of the tape, which makes it difficult to put it into practical use.

In the present invention, it is preferable to provide a coating layer C containing inert particles C on the surface of the thermoplastic resin layer A which is not in contact with the coating layer B in order to impart the film winding property.

The coating layer C may be formed as a coating layer,
Further, it may be formed by a co-extrusion method described later. When the coating layer C is a coating layer, the inactive particles C contained are composed of a single particle or two or more kinds of particles having different sizes, and the single particle and the average of the largest particles in the case of two or more kinds of particles. The particle size is 20 to 200 nm, preferably 30 to 100 nm. The content of the inert particles C in the coating layer C is 3 to 50% by weight, preferably 5 to 30% by weight. When the average particle size of the particles C is less than 20 nm or less than 3% by weight, the film winding property, the transport property in the film forming step, and the like are insufficient, and blocking is easily caused. . On the other hand, when the average particle size exceeds 200 nm, the particles easily fall off the coating film. When the content of the inert particles C in the coating layer C exceeds 50% by weight, the strength of the coating layer C itself decreases, and the coating layer C is easily chipped.

As the inert particles C contained in the film forming layer C, polystyrene, polystyrene-divinylbenzene,
Organic particles such as polymethyl methacrylate, methyl methacrylate copolymer, cross-linked methyl methacrylate copolymer, polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, benzoguanamine resin, silica, alumina, titanium dioxide, kaolin, talc Any of inorganic particles such as graphite, graphite, calcium carbonate, feldspar, molybdenum disulfide, carbon black and barium sulfate may be used. Further, the particles may be shell core particles used for the coating layer B.

As the resin containing the particles C and forming the coating layer, the same resin as the aqueous resin used for forming the coating layer B can be exemplified. These may further contain a cellulose resin.

When the coating layer C is formed by the coextrusion method, the inert particles C contained are composed of a single particle or two or more kinds of particles having different sizes, and the single particle or two or more kinds of particles. Average particle size of the largest particles is 100-100
0 nm, preferably 100-500 nm. The content of the inert particles C in the coating layer C is 0.001 to 5.0% by weight, preferably 0.005 to 1.0% by weight. When the average particle size is less than 100 nm or the content is less than 0.001% by weight, the film is insufficient in winding property, transportability in a film forming process, and the like, and tends to cause blocking. When the average particle size exceeds 1000 nm or the content exceeds 5.0% by weight, the coating layer B
The push-up effect to the side surface becomes remarkable, and the electromagnetic conversion characteristics deteriorate.

As the kind of the inert particles C, the same particles as those used when the coating layer C is used as the coating layer can be exemplified.

The laminated film of the present invention can be manufactured by a conventionally known method or a method accumulated in the art.

For example, the biaxially oriented polyester film will be described. In the case of the coating method, first, the thermoplastic resin A is extruded from the die at a temperature of melting point Tm ° C. to (Tm + 70) ° C. into a film shape, and then 40 to 90 ° C. And rapidly solidified to obtain an unstretched film. Thereafter, the unstretched film is uniaxially (longitudinal or transverse) (Tg-10) according to a conventional method.
At a temperature of (Tg + 70) ° C. (Tg: glass transition temperature of polyester) at a draw ratio of 2.5 to 8.0 times, preferably at a draw ratio of 3.0 to 7.5 times, and then a film The coating liquid for forming the layers B and C is applied to both sides of the film, and thereafter, at a temperature of Tg to (Tg + 70) ° C. in a direction perpendicular to the above direction at a magnification of 2.5 to 8.0 times, preferably 3.0. ~
Stretch at a magnification of 7.5 times. Further, if necessary, it may be stretched again in the machine direction and / or the transverse direction. That is, 2 steps, 3
It is advisable to carry out stretching in four steps or four steps. The total draw ratio is generally 9 times or more, preferably 12 as an area draw ratio.
˜35 times, more preferably 15 to 32 times. Further, subsequently, the biaxially oriented film is changed from (Tg + 70) to (Tm
Excellent dimensional stability is imparted by heat-fixing crystallization at a temperature of −10) ° C., for example 180 to 250 ° C.
The heat fixing time is preferably 1 to 60 seconds.

In the case of the coextrusion method, two kinds of thermoplastic resins for layer A and layer C are melted in the extrusion die or before the die (generally, the former is called a multi-manifold system, the latter is called a feed block system). Laminated and compounded, and coextruded at a suitable thickness ratio to obtain a two-layer unstretched film,
In addition, the same coating method as described above may be applied, except that the coating liquid for forming the coating layer B is applied after the uniaxial stretching. By this method, a biaxially oriented laminated polyester film having good interlayer adhesion can be obtained.

In the production of the laminated film, the thermoplastic resin may optionally contain additives other than the above-mentioned inert particles such as a stabilizer, a colorant, and a specific resistance adjusting agent for the molten polymer.

The laminated film of the present invention is a ferromagnetic film made of iron, cobalt, chromium or an alloy or oxide containing these as the main components on the surface of the coating layer B by a method such as vacuum deposition, sputtering or ion plating. A metal thin film layer is formed, and a protective layer such as diamond-like carbon (DLC) is formed on the surface of the metal thin film layer for the purpose, purpose, and need.
By sequentially providing a fluorine-containing carboxylic acid-based lubricating layer and further providing a known back coat layer on the surface of the thermoplastic resin layer A or the coating layer C, the output in the short wavelength region, S / N, C
/ N or the like, and can be a vapor-deposited magnetic recording medium for high-density recording with low dropout and low error rate. This vapor-deposited type electromagnetic recording medium includes a Hi8 for recording an analog signal, a digital video cassette recorder (DVC) for recording a digital signal, 8 mm data, and a DD.
It is extremely useful as a tape medium for SIV.

The laminated film of the present invention also has a coating layer B.
On the surface of, iron or fine needle-shaped magnetic powder containing iron as a main component is uniformly dispersed in a binder such as vinyl chloride, vinyl chloride / vinyl acetate copolymer, and the magnetic layer thickness is 1 μm or less, preferably 0.1 to 1 μm, and further by providing a back coat layer on the surface of the thermoplastic resin layer A or the coating layer C by a known method, particularly in the short wavelength region, such as S / N and C / N. A metal-coated magnetic recording medium for high-density recording with excellent electromagnetic conversion characteristics and low dropout and error rate can be obtained. If necessary, a non-magnetic layer containing fine titanium oxide particles and the like is dispersed and coated on the coating layer B as an underlayer of the metal powder-containing magnetic layer in the same organic binder as the magnetic layer. You can also This metal-coated magnetic recording medium includes 8 mm video for recording analog signals, Hi8, β cam SP, W-VHS,
Digital video cassette coder (DVC) for digital signal recording, data 8 mm, DDSIV, digital β
It is extremely useful as a tape medium for cams, D2, D3, SX and the like.

The laminated film of the present invention also has a coating layer B.
On the surface of, needle-shaped fine magnetic powder such as iron oxide or chromium oxide,
Alternatively, plate-like fine magnetic powder such as barium ferrite is uniformly dispersed in a binder such as vinyl chloride, vinyl chloride / vinyl acetate copolymer, and applied so that the magnetic layer thickness is 1 μm or less, preferably 0.1 to 1 μm. Further, by providing a back coat layer on the thermoplastic resin layer A or the coating layer C by a known method, output in a short wavelength region, S /
Excellent in electromagnetic conversion characteristics such as N, C / N, dropout,
A coating type magnetic recording medium for high density recording with a low error rate can be obtained. If necessary, a non-magnetic layer containing fine titanium oxide particles and the like is dispersed and coated on the coating layer B as an underlayer of the metal powder-containing magnetic layer in the same organic binder as the magnetic layer. You can also do it. This oxide-coated magnetic recording medium is useful as a high-density oxide-coated magnetic recording medium such as a data streamer QIC for digital signal recording.

The above-mentioned W-VHS is an analog HDTV signal recording VTR, and DVC is a digital HDTV.
The film of the present invention is applicable to recording of a TV signal, and can be said to be a very useful base film for these magnetic recording media for HDTV-compatible VTRs.

[0057]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. The measuring method used in the present invention is as follows.

(1) Average particle size I (average particle size: 0.
06μm or more) Shimadzu CP-50 Centrifugal Particle Size Analyzer (Centrifugal Particle)
It is measured using a Size Analyzer). From the integrated curve of particles of each particle size and its abundance calculated based on the obtained centrifugal sedimentation curve, the particle size “equivalent sphere diameter” corresponding to 50 mass percent is read, and this value is defined as the above average particle size. (Book
"Granularity measurement technology", published by Nikkan Kogyo Shimbun, 1975, page 2
42-247).

(2) Average particle size II of particles (average particle size: 0.
Particles having an average particle size of less than 0.06 μm, which form small protrusions,
It is measured using a light scattering method. That is, Nicomp In
instruments Inc. NICOMP M
ODEL 270 SUBMICRON PARTIC
Expressed as the "equivalent spherical diameter" of the particle at the point of 50% by weight of the total particle as determined by LE SIZER.

(3) Volume shape factor f A photograph of each particle was taken at a magnification corresponding to the size used by a scanning electron microscope, and the maximum diameter of the projection surface was measured using an image analysis processor Luzex 500 (manufactured by Nippon Regulator). Then, the volume of the particles is calculated and calculated by the following formula.

[0061]

F = V / d ³ , where f is the volume shape factor, V is the volume of the particle (μm ³ ),
d represents the maximum diameter (μm) of the projection surface.

(4) Layer thickness and core part particle diameter of core-shell particles The total thickness of the film is 10 at random with a micrometer.
Measure the points and use the average value. The layer thickness is determined by measuring the layer thickness on the thin side by the method described below, and subtracting the layer thickness on the thick side from the layer thickness on the thinner side than the total thickness. That is, using a secondary ion mass spectrometer (SIMS), a concentration ratio (M ⁺ /) of an element originating from the highest concentration particle among the particles in the film having a depth of 5000 nm from the surface layer to the carbon element of the polyester. C ⁺ ) is defined as the particle concentration and the depth from the surface is 500
Analysis in the thickness direction is performed up to 0 nm. In the surface layer, the particle concentration is low due to the interface of the surface, and the particle concentration increases as the distance from the surface increases. In the case of the present invention, there are cases where the particle concentration once reaches a stable value 1 and then increases or decreases to a stable value 2 and cases where the particle concentration monotonously decreases. Based on this distribution curve, the former has a depth giving a particle concentration of (stable value 1 + stable value 2) / 2, and the latter has a depth at which the particle concentration becomes 1/2 of the stable value 1. (This depth is stable 1
Is greater than the depth of the layer).

The measurement conditions are as follows. Measuring device Secondary ion mass spectrometer (SIMS): PERKIN
ELMER 6300 Measurement conditions Primary ion species: O2 + Primary ion acceleration voltage: 12 KV Primary ion current: 200 nA Raster area: 400 μm □ Analysis area: Gate 30% Measurement vacuum degree: 6.0 × 10 ⁻⁹ Torr E-GUNN: 0 When the particles most contained in the range of 5000 nm from the surface layer are organic polymer particles other than the silicone resin, SI
Since measurement is difficult with MS, the same concentration distribution curve as above is measured by FT-IR (Fourier transform infrared spectroscopy) while etching from the surface, or XPS (X-ray high electron spectroscopy) depending on the particles, and the layer is measured. Find the thickness.

The above is an effective measuring method in the case of the coextrusion layer. In the case of the coating layer, a small piece of the film is fixed and molded with an epoxy resin, and an ultrathin section (film of the film) having a thickness of about 60 nm is formed by a microtome. Cut parallel to the flow direction) and make a transmission electron microscope (Hitachi H-
(Type 800), and the layer thickness is determined from the boundary surface between the layers. The particle size of the core portion of the core-shell particles is also obtained by observing from the cross section of this ultrathin section.

(5) AFM surface roughness ARa and ARz Ara (root mean square roughness) and ARz (calculated as root mean square roughness) calculated under the following conditions using a J scanner of an atomic force microscope Nano Scope III AFM manufactured by Digital Instruments. 10-point average roughness) is measured. Probe; single bond silicon sensor Scanning mode: tapping mode Scanning range: 2 μm × 2 μm Pixels: 256 × 256 data points Scanning speed: 2.0 Hz Measurement environment: room temperature, in air

(6) Number of particle projections and agglomeration rate Using a SEM (scanning electron microscope, model T-300 manufactured by JEOL Ltd.), the surface of the laminated film was magnified 30,000 times at an angle of 0 °.
, And the number of granular projections is counted, and the average value is calculated as the number of projections per piece / mm ² by area conversion. The aggregation rate is calculated by the following formula using the same SEM photograph. Aggregation rate (%) = [(total number of aggregates in which two or more particles aggregate) / (total number of one or more particles)] × 100

(7) Height and frequency of protrusions due to macro-aggregates An aluminum thin film was formed on the surface of the coating layer B of the laminated film by a vacuum vapor deposition method so that the thickness was 0.2 μm from an angle of inclination of 45 °. Scanning and observing 1 cm ² with a transmission microscope at a magnification of 400 times, and counting the number of transmitted lights having a maximum length of non-deposited portion (corresponding to the height of the protrusion) of 0.2 mm or more due to the shadow of the protrusion. (That is, the height is 0.2mm / 400
= Count the protrusion frequency due to coarse macro-aggregates of 0.5 μm or more. )

(8) Scraping resistance The film was sampled in a length of 25 to 30 cm and a width of 1/2 inch, and a leather blade was applied under the conditions of an angle of 90 ° with respect to the surface of the coating layer B and a depth of 0.5 mm. , Load 500g /
The width in the depth direction of the shaving powder adhering to the razor blade when running at a speed of 0.5 cm and a speed of 6.7 cm / sec was determined by taking a microphotograph (× 160). When the width of the shavings in the depth direction is 3 μm or less (◎), 3 to 5 μm (○), 5
μm or more is defined as (×). The smaller the depth of the shavings in the depth direction, the better the sharpness.

(9) Winding property After optimizing the winding condition at the slit, the width is 560 mm ×
The roll having a size of 9000 m is slit by 10 rolls, left for 1 week, and free from film wrinkles. The roll is evaluated as a good product according to the following criteria. Number of good rolls Judgment criteria 8 or more ◎ 5 to 7 ○ 3 to 4 × 2 or less ××

(10) Production of magnetic tape and evaluation of characteristics On the surface of the coating layer B of the laminated film, a vacuum vapor deposition method was used.
A ferromagnetic thin film of 100% cobalt is formed in two layers (each layer thickness is about 0.1 μm) so as to have a thickness of 0.02 μm, and a diamond-like carbon (DLC) film and a fluorine-containing carboxylic acid-based lubricating layer are formed on the surface. A back coat layer is formed on the surface of the thermoplastic resin A or the coating layer C by a known method. After that, slit to a width of 8 mm, 8 mm on the market
Load in video cassette. Next, the properties of the tape are measured using the following commercially available equipment. Equipment used: 8mm video tape recorder: EDV manufactured by Sony Corporation
-6000 C / N measurement: Noise meter manufactured by Shibasoku Co., Ltd.

C / N measurement A signal having a recording wavelength of 0.5 μm (frequency of about 7.4 MHz) was recorded, and the ratio of the value of 6.4 MHz and the value of 7.4 MHz of the reproduced signal was used as the C / N of the tape, which was commercially available. The C / N of the vapor deposition tape for 8 mm video is defined as OdB, and the relative value is shown. ◎: +2 dB or more: -1 to +2 dB ×: -4 to -2 dB XX: -4 dB or less

Dropout (D / O) measurement Using a dropout counter, 15 μs / 18 d
At B, measure the number per minute. ◎: 0 to 10 pieces / min: 10 to 20 pieces / min ×: 20 to 50 pieces / min XX: 50 pieces / min or more

Running Durability At 40 ° C. and 80% RH, C / N was measured after tape was recorded and reproduced 500 times at a running speed of 85 cm / min.
The deviation from the initial value is judged according to the following criteria. ◎: +0.0 dB or more with respect to the initial value ○: -1.0 dB to +0.0 dB with respect to the initial value ×: less than -1.0 dB with respect to the initial value

[Example 1] Dimethyl terephthalate and ethylene glycol were added, manganese acetate was used as a transesterification catalyst, antimony trioxide was used as a polymerization catalyst, and phosphorous acid was added as a stabilizer. Polyethylene tephthalate (P containing no inert particles)
ET).

170% of this polyethylene terephthalate
After drying at ℃ for 3 hours, it is fed to the extruder and melted at 280
It was melted at ˜300 ° C., extruded in a sheet form from a die, and rapidly cooled to obtain an unstretched film having a thickness of 82 μm.

The obtained unstretched film was preheated, further stretched 3.2 times in the machine direction at a film temperature of 95 ° C. between low-speed and high-speed rolls, rapidly cooled, and then on one side of the machine-stretched film. 0.005 μm each of the aqueous coating liquid containing the aqueous resin of the coating layer B and the particles B in Tables 1 and 2 and the aqueous coating liquid containing the resin of the coating layer C and the particles C on the other side, respectively.
It was applied to a thickness of 0.015 μm (after stretching and drying), subsequently supplied to a stenter, and stretched 4.1 times in the transverse direction at 110 ° C. The obtained biaxially stretched film was
The film was heat-set with hot air at 0 ° C. for 4 seconds to obtain a laminated biaxially oriented polyester film having a thickness of 5.9 μm.

[Example 2, Comparative Examples 1, 2, 5, 6] The procedure was carried out except that the resins and particles of the coating layer B and the coating layer C, and the thickness of the thermoplastic resin layer A were changed as shown in Tables 1 and 2. A laminated biaxially oriented polyester film was obtained in the same manner as in Example 1.

[Example 3 and Comparative Example 9] Polyethylene terephthalate for the thermoplastic resin layer A and the coating layer C shown in Tables 1 and 2 were respectively supplied to two extruders to form a multi-manifold type co-extrusion die. The laminated biaxially oriented polyester film is laminated in the same manner as in Example 1 except that the aqueous coating solution containing the resin and particles of the coating layer B in Table 1 is applied to the surface opposite to the surface on the coating layer C side. Got

[Examples 4 and 5, Comparative Examples 3, 7, 8, 1
1] Polyethylene-2,6-naphthalate (in the same manner as in Example 1 except that the particles shown in Tables 1 and 2 were used, and the same molar amount of dimethyl 2,6-naphthalenedicarboxylate was used instead of dimethyl terephthalate ( PEN) was obtained.

After drying this polyethylene-2,6-naphthalate at 170 ° C. for 6 hours, an unstretched film satisfying each of the examples and comparative examples was obtained in the same manner as in Example 1.

The obtained unstretched film was preheated, further stretched 3.6 times in the machine direction at a film temperature of 135 ° C. between low-speed and high-speed rolls, and rapidly cooled, and then the coating layers shown in Tables 1 and 2 were obtained. The aqueous coating liquids of B and the coating layer C were applied in the same manner as in Example 1, subsequently supplied to a stenter, and stretched 6.0 times in the transverse direction at 155 ° C. The obtained biaxially stretched film is 20
The film was heat-set with hot air at 0 ° C. for 4 seconds to obtain a laminated biaxially oriented polyester film.

[Example 6, Comparative Examples 4 and 10] Laminated biaxially produced by the same method as in Example 3 except that polyethylene 2,6-naphthalate is used as shown in Tables 1 and 2 instead of polyethylene terephthalate. An oriented polyester film was obtained.

[0083]

[Table 1]

[0084]

[Table 2]

The surface characteristics of the laminated biaxially oriented films obtained in the above Examples and Comparative Examples, the ratio of the particle size d _B of the shell core particles to the particle size of the core part d _B / dc _B , and the layer thickness t of the coating layer B. _B
And the particle diameter dc _B of the core portion of the shell core particle t _B / dc
Table 3 shows _B , abrasion resistance, and winding property, and the characteristics of the ferromagnetic thin film vapor-deposited magnetic tape using this film.

[0086]

[Table 3]

As is clear from Table 3, the laminated film according to the present invention is excellent in shaving property and winding property in the film forming process, and has electromagnetic conversion characteristics, dropout characteristics, running durability when used as a magnetic recording medium. Extremely excellent in On the other hand, those which do not satisfy the requirements of the present invention cannot simultaneously satisfy these characteristics.

[0088]

INDUSTRIAL APPLICABILITY According to the present invention, it is useful as a base film of a magnetic recording medium which is excellent in abrasion resistance and winding property in a film forming process and is also excellent in electromagnetic conversion characteristics, dropout characteristics and running durability. A laminated film can be provided.

Claims (14)

[Claims] On at least one surface of 1. A substantially thermoplastic resin layer A containing no inert particle, the aqueous resin and average particle diameter d _B is 5 to 100 nm, a volume shape factor of 0.1~π / 6
A particle B having a core-shell structure in which the outside is more flexible than the inside
A laminated film obtained by laminating a coating layer B containing
The average particle diameter d _B of the particle B (nm), particle size dc _B of the core portion of the particles B (nm), and the layer thickness t _B of the coating layer B (nm) is represented by the following formula (1), (2) at the same time Satisfaction, the frequency of surface protrusions by the particles B of the coating layer B is 1 × 10 ⁶ to 1 × 10 ⁸ pieces /
mm ^2, and the laminated film having protrusions frequency of height by macro aggregates than 0.5μm particles B is equal to or is 50 / cm ² or less. [Equation 1] 1.01 ≦ d _B / dc _B ≦ 3.0 (1) [Equation 2] 0.05 ≦ t _B / dc _B ≦ 0.8 (2) 2. The laminated film according to claim 1, wherein the agglomeration rate of the particles B in the coating layer B is 10% or less. 3. The laminated film according to claim 1, wherein the water-based resin comprises at least one water-based resin selected from acrylic resins, polyester resins and acrylic-polyester resins. 4. The surface roughness ARa _B (nm) and the 10-point average roughness ARz _B (nm) of the coating layer B measured by an atomic force microscope (AFM) satisfy the following formulas (3) and (4). The laminated film according to claim 1, which is satisfied at the same time. Equation 3 0.3 ≦ ARa _B ≦ 5.0 (3) Equation 4 10 ≦ ARz _B ≦ 100 (4) 5. The laminated film according to claim 1, wherein a coating layer C containing inert particles C is laminated on the surface of the thermoplastic resin layer A which is not in contact with the coating layer B. 6. The laminated film according to claim 5, wherein the coating layer C is a coating layer. 7. The inactive particles C in the coating layer C are composed of individual particles or two or more kinds of particles having different sizes, and the average particle diameter of the single particles or the average particle of the largest particles of the two or more kinds of particles. The laminated film according to claim 6, having a diameter of 20 to 200 nm and a content of particles C of 3 to 50% by weight. 8. The laminated film according to claim 5, wherein the coating layer C is a coextrusion layer. 9. The inactive particles C in the coating layer C are composed of individual particles or two or more kinds of particles having different sizes, and the average particle diameter of the single particles or the largest particle of the two or more kinds of particles. The diameter is 0.1 to 1 μm, and the content of particles is 0.1.
The laminated film according to claim 8, which is 001 to 5.0% by weight. 10. The total thickness of the laminated film is 2.5 to 20.
The laminated film according to claim 1, wherein the laminated film has a thickness of μm. 11. The laminated film according to claim 1, which is a base film of a magnetic recording medium. 12. The laminated film according to claim 11, wherein the magnetic recording medium is a metal thin film type magnetic recording medium. 13. A magnetic recording medium having a magnetic layer thickness of 1 μm.
The laminated film according to claim 11, which is the following coating type magnetic recording medium. 14. The laminated film according to claim 11, 12 or 13, wherein the magnetic recording medium is a digital signal recording type magnetic recording medium.