JP3229192B2 - Laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film, and more particularly, to a magnetic recording excellent in winding property, easy sliding property, handling property, etc., and excellent in electromagnetic conversion characteristics, dropout and running durability of a magnetic layer surface. The present invention relates to a laminated film useful as a base film of a medium.

[0002]

2. Description of the Related Art In recent years, remarkable progress has been made in increasing the density of magnetic recording media. For example, a 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. The development and commercialization of a thin-layer coated magnetic recording medium in which a needle-shaped magnetic powder such as a metal powder or an iron oxide powder is coated to a thickness of 2 μm or less has been promoted. Examples of the former include, for example, a vapor deposition tape of Co (JP-A-54-147010) and a perpendicular magnetic recording medium made of a Co-Cr alloy (JP-A-52-134706).
For example, high density magnetic recording using an ultrathin coating magnetic recording medium (Technical Report of the Institute of Electronics and Communication Engineers MR94-78 (1995-02)) and the like are known. .

Conventional coating type magnetic recording media (magnetic recording media obtained by mixing 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 layer is as thick as about 2 μm or more, the ferromagnetic metal thin film formed by thin film forming means such as vacuum deposition, sputtering or ion plating has a very thin thickness of 0.2 μm or less and is extremely thin. Also in the case of the layer coating type, although the non-magnetic underlayer is provided,
A thickness of μm has been proposed and is very thin.

For this reason, in the above-mentioned high-density magnetic recording medium, the surface condition of the non-magnetic support (base film) has a great influence on the surface properties of the magnetic layer. Indicates that the surface state of the nonmagnetic support is directly expressed as irregularities on the surface of the magnetic layer (magnetic recording layer),
This causes noise in the recording / reproducing signal. Therefore, it is desirable that the surface of the non-magnetic support is as smooth as possible.

[0005] On the other hand, from the viewpoint of handling such as film formation of a non-magnetic support (base film), transport in processing steps, scratching, winding and unwinding, if the film surface is too smooth, the film-to-film mutual contact will occur. The slip property deteriorates, the booking phenomenon occurs, the shape when wound on a roll (roll formation) deteriorates, the product yield decreases,
As a result, the production cost of the product increases. Therefore, from the viewpoint of manufacturing cost, a non-magnetic support (base film)
Is desirably 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 is required to be rough from the viewpoint of handling properties and film cost.

Further, in the case of a metal thin film type magnetic recording medium, a serious problem when actually used is the running property of the metal thin film surface. In the case of a coating type magnetic recording medium in which a magnetic material powder is mixed in an organic polymer bander and applied to a base film, a lubricant is dispersed in the binder to improve the running property of the magnetic layer surface. I can,
In the case of a metal thin film type magnetic recording medium, such measures cannot be taken, and it is extremely difficult to maintain a stable running property. Have. Further, in this case, there is a drawback that the output value under repeated use is larger than that of the coating type magnetic recording medium.

Therefore, in order to manufacture a high-density magnetic recording medium of excellent quality, it is necessary to simultaneously satisfy the above two conflicting properties.

As a specific method for this purpose, a method of applying a specific coating agent to the film surface 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
No. 8223), a method of applying and forming a continuous film having fine irregularities on the film surface (JP-A-5-194772).
And Japanese Patent Application Laid-Open No. 5-210833, and a method for forming a front and back surface by co-extrusion and the like (Japanese Patent Application Laid-Open No. 2-214657).
, Japanese Patent Publication No. Hei 7-80282), or a method in combination with (Japanese Patent Laid-Open No. 3-73409).

[0010]

However, in the above-mentioned method of applying a discontinuous film or a continuous film having fine irregularities by coating, the problems such as slipping between films and blocking can be solved. In the film forming process, the film is scraped off by contact with various guide rolls, adheres and accumulates on the base film to form protrusions, which causes a new problem of dropout when magnetic tape is formed. Would.

The conventional co-extrusion technique or the technique of combining the co-extrusion technique with a discontinuous film or a continuous film has the same problem, and the rough surface projections are transferred to a flat surface. This causes a problem that a flat surface is roughened. This phenomenon is particularly remarkable on the inner layer side of a film roll wound at a high winding pressure. As a result, even when a magnetic tape is manufactured with the same formulation using the same base film roll, there is a large difference in the electromagnetic conversion characteristics between the tape using the roll surface layer and the tape using the roll core layer. turn into.

Further, in the case of a vapor-deposited metal thin film type magnetic recording medium, there still remains a problem of running durability.

[0013] The object of the present invention is to solve the drawbacks of the prior art, to excel in shaving and winding properties in the film forming process, and to make no difference in quality between the surface layer portion and the core layer portion of the base film roll.
An object of the present invention is to provide a laminated film having excellent running durability when used as a vapor-deposited metal thin film type magnetic recording medium.

[0014]

The present invention has the following configuration to achieve the above object.

A thermoplastic resin layer B containing inert particles B is laminated on one surface of the thermoplastic resin layer A, and a coating layer C is coated on the other surface of the thermoplastic resin layer A. Laminated film, and contained in the thermoplastic resin layer B.
Average particle size d of the largest particle among the inert particles B
_B is 0.1 to 1 [mu] m, 0.001 to its content C _B
0.5 wt%, the layer thickness t _B of the thermoplastic resin layer B
(Nm), the average particle diameter d _B (μm) of the largest particles among the inert particles B and the content C _B (% by weight) satisfy the following formula (1), and Atomic force microscope (A
A laminated film characterized in that the center plane ten-point average roughness Rz (nm) and the center plane average roughness Ra (nm) measured by FM) satisfy the following expression (2).

[0016]

0.1 ≦ (d _B ) ³ × C _B × t _B ≦ 10 (1)

[0017]

8 ≦ Rz / Ra ≦ 40 (2) As the thermoplastic resin in the present invention, polyester resin, polyamide resin, polyimide resin, polyether resin, polycarbonate resin, polyvinyl resin, Examples thereof include polyolefin-based resins.
Of these, polyester 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.

These polyesters may be homopolyesters or copolyesters. In the case of a copolyester, for example, as a copolymer component of polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate, for example, diethylene glycol,
Other diol components such as propylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, polyethylene glycol, 1,4-cyclohexanedimethanol, p-xylene glycol, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid Acid (however, polyethylene-2,6-naphthalenedicarboxylate), 2,6-naphthalenedicarboxylic acid (however, polyethylene terephthalate), other dicarboxylic acid components such as 5-sodium sulfoisophthalic acid, p- Oxycarboxylic acid components such as oxyethoxybenzoic acid and the like can be mentioned. The amount of these copolymer components is preferably at most 20 mol%, more preferably at most 10 mol%.

Further, a trifunctional or higher polyfunctional compound such as trimellitic acid or pyromellitic acid can be copolymerized. In this case, it is preferred that the polymer is copolymerized in a substantially linear amount, for example, 2 mol% or less.

The above polyesters are known per se and can be produced by a method known per se.

In the present invention, the laminated film has a thermoplastic resin layer A and a thermoplastic resin layer B.
May be the same or different. Among them, the same resin is preferable. Particularly, it is preferable that the layers A and B are made of polyethylene terephthalate or polyethylene-2,6-naphthalenedicarboxylate. These polyesters have an intrinsic viscosity of about 0.4 measured at 35 ° C. as a solution in o-chlorophenol.
~ 0.9 is preferred.

In the present invention, the laminated film is formed by laminating a thermoplastic resin layer B containing one or more kinds of inert particles B on one surface of a thermoplastic resin layer A, and forming a specific film on the other surface of the layer A. A coating layer C having surface properties is applied. If the thermoplastic resin layer B containing the inert particles B is not laminated, the base film becomes extremely flat, so that handling properties such as scratching, winding and unwinding in the film forming process of the film are caused. In addition, the blocking property occurs due to the deterioration of the slipperiness between the films, and the shape (roll formation) when wound on a roll is deteriorated, and the productivity is lowered, the product yield is reduced, and the product is deteriorated. Causes an increase in manufacturing costs.

In the thermoplastic resin layer B, the average particle diameter d _B (μm) of the largest particles among the inert particles B, the content C _B (% by weight) thereof, and the layer thickness t _B (nm) are different. The following expression (1), preferably the following expression (1-1) is satisfied.

[0025]

0.1 ≦ (d _B ) ³ × C _B × t _B ≦ 10 (1)

[0026]

Equation 8] ^{_{0.2 ≦ (d B) 3 ×}} C B × t B ≦ 8 ...... (1-1) more preferably satisfies the following formula (1-2).

[0027]

Equation 9] In ^{_{0.3 ≦ (d B) 3 ×}} C B × t B ≦ 5 ...... (1-2) the value ^{_{((d B) 3 × C}} B × t B) is less than 0.1,
Since the surface of the thermoplastic resin layer B becomes too flat, even if the coating layer C is present, the slipperiness of the film-film becomes worse. Is easily formed, resulting in a decrease in yield. On the other hand, if this value exceeds 10,
Although the winding property is good, the transfer of projections to a flat surface is extremely easy to occur. Particularly, when a long roll of 10,000 m to 20,000 m is wound, the vicinity of the core layer of the roll with higher pressure and the roll surface layer In the vicinity, there is a remarkable difference in the surface properties of the film.

[0028] Here, the average particle diameter d _B of the largest particles of the inert particles B, the average particle diameter of the single particles when the inert particles B is composed of one single particles and the size When it is composed of two or more kinds of particles having different average particle diameters, it is the average particle diameter of the particles having the largest average particle diameter.

The average particle diameter d _B of the largest particles 0.
1-1 μm, preferably 0.15-0.8 μm, further
Preferably Ru 0.2~0.7μm der. The content of the largest particles with an average particle diameter d _B is of the thermoplastic resin layer B, 0. 001 to 0.5% by weight , preferably
The Ru 0.005 to 0.1% by weight der.

Examples of the inert particles having an average particle diameter d _B, for example, (1) particulate polymer particles (such as crosslinked silicone resin, crosslinked polystyrene, crosslinked acrylic resin, melamine - formaldehyde resin, aromatic polyamide resin, polyimide resin, (2) metal oxides (for example, aluminum trioxide, titanium dioxide, silicon dioxide,
Magnesium oxide, zinc oxide, zirconium oxide, etc.),
(3) metal carbonates (eg, magnesium carbonate, calcium carbonate, etc.), (4) metal sulfates (eg, calcium sulfate, barium sulfate, etc.), (5) carbon (eg, carbon black, graphite, diamond, etc.), and (6) Clay minerals (eg, kaolin, clay, bentonite, etc.) are preferred. Among these, crosslinked silicone resin particles, crosslinked polystyrene particles, melamine-formaldehyde resin particles, polyamideimide resin particles, aluminum trioxide (alumina), titanium dioxide, silicon dioxide, zirconium oxide, synthetic calcium carbonate, barium sulfate, diamond and diamond Kaolin is preferred, and crosslinked silicone resin particles, crosslinked polystyrene particles, alumina, titanium dioxide, silicon dioxide and synthetic calcium carbonate are particularly preferred.

Furthermore, if the inert particles B is composed of two or more particles, the second, third particles of small average particle diameter than the average particle diameter d _B of the largest particles above, for example colloidal silica, Fine particles such as alumina having crystal forms such as α, γ, δ, and θ can be preferably used.
It can also be used a small fine particle average particle diameter of the illustrated particles species as inert particles having an average particle diameter d _B.

The fine particles have an average particle size of 5 to 400 n.
m, further 10 to 300 nm, especially in the range of 30 to 250 nm, and the average particle diameter d 50 nm or more than _B, further 100nm or more, and particularly preferably 150nm or more small. The content of the second and third particles (fine particles) is 0.005 to 1% by weight, more preferably 0.01 to 0.7% by weight, and particularly 0.05 to 1% by weight, based on the thermoplastic resin layer B.
Preferably, it is 0.5% by weight.

The surface roughness of the thermoplastic resin layer B according to the present invention is set so that the center plane average roughness WRa ^B measured by a non-contact three-dimensional roughness meter is 0.5 nm or more and less than 5 nm from the viewpoint of transfer suppression. Preferably, there is. Further, it is preferable that this WRa ^B is larger than the center plane average roughness WRa ^C of the coating layer C. WRa ^B is more preferably in the range of 0.8 nm or more and less than 4.5 nm, particularly 1.0 nm or more and less than 4.0 nm.

In the present invention, one surface of the laminated film is formed of the thermoplastic resin layer B, but the properties of the layer B alone are insufficient for the slipperiness between the films, and particularly at high speed. A bump-like projection is easily generated due to blocking between the films during winding. Therefore, the other surface of the laminated film is formed of a coating layer C having specific surface characteristics. The coating layer C further improves the slipperiness between the films, and also improves the running durability especially when used as a base film of a deposited metal thin film type magnetic recording medium.

The coating layer C according to the present invention has a center plane ten-point average roughness Ra (n) measured by an atomic force microscope (AFM).
m) and the center plane average roughness Ra (nm) satisfy the following expression (2), preferably the following expression (2-1).

[0036]

8 ≦ Rz / Ra ≦ 40 (2)

[0037]

12 ≦ Rz / Ra ≦ 36 (2-1) More preferably, the following expression (2-2) is satisfied.

[0038]

12 ≦ Rz / Ra ≦ 32 (2-2) If this value (Rz / Ra) is less than 8, the running durability of the deposited metal thin film type magnetic recording medium is inferior. If (Rz / Ra) exceeds 40, shavings are likely to be generated due to contact with guide rolls, nip rolls, and the like during the film forming process, which adhere to and accumulate on the base film and cause dropout. Become.

The coating layer C does not have to contain inert particles, but the inert particles C having an average particle diameter of 10 to 50 nm have a surface fine protrusion frequency of 2 to 20 million particles / m 2.
It is preferable that the content of m ² be contained since the running durability is further improved. The average particle size of the inert particles C is more preferably 15 to 45 nm, and further preferably 18 to 4 nm.
2 nm. The frequency of the fine projections is more preferably 2.5 to 18 million / mm ² , and still more preferably 3 to 15 million / mm ² . The fine projections preferably have a height of 3 times the average particle size of the inert particles C.
0% or more and less than 200%, more preferably 40 to 180%
%, Particularly preferably 50 to 160%.

Although the type of the inert particles C is not particularly limited, those having a relatively low specific gravity which does not easily settle in the coating liquid are preferred. For example, particles made of a heat-resistant polymer (for example, a crosslinked silicone resin, a crosslinked acrylic resin, a crosslinked polystyrene, a melamine / formaldehyde resin, an aromatic polyamide resin, a polyamideimide resin, a crosslinked polyester, a wholly aromatic polyester, etc.), silicon dioxide (silica) ),
Preferred are calcium carbonate and the like. Among these, cross-linked silicone resin, silica, and core-shell type organic particles (core: cross-linked polystyrene, shell: polymethyl methacrylate, etc.) are particularly preferable.

In the coating layer C of the present invention, a binder resin is used to fix the inert particles C. Examples of the binder resin include an aqueous polyester resin and
Aqueous acrylic resins, aqueous polyurethane resins and the like are preferred, and aqueous polyester resins are particularly preferred.

As the aqueous polyester resin, acid components include, for example, 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-N
a a sulfoisophthalic acid, 2-K sulfoterephthalic acid, trimellitic acid, trimesic acid, monopotassium trimellitic acid salt, a polycarboxylic acid such as P-hydroxybenzoic acid, and a glycol component such as ethylene glycol;
Diethylene glycol, propylene glycol, 1,4
-Butanediol, 1,6-hexanediol, 1,4
Preferred examples include polyester resins mainly composed of polyvalent hydroxy compounds such as cyclohexanedimethanol, P-xylylene glycol, dimethylolpropanoic acid, and ethylene oxide adduct of bisphenol A, and an acrylic polymer chain bonded to a polyester chain. Graft polymers or block copolymers, or two polymers, have a specific physical configuration (IPN,
An acrylic-modified polyester resin forming the core shell) may be used. As this aqueous polyester resin,
Any type that dissolves, emulsifies, or finely disperses in water can be used freely, and these may have, for example, a sulfonic acid group, a carboxylic acid group, or a polyether unit introduced in the molecule to impart hydrophilicity. .

The thermoplastic resin layer A in the present invention may not contain inert particles, but preferably has an average particle size of 40 to 400 nm, more preferably 50 to 200 nm.
nm, particularly preferably from 60 to 120 nm, and having a volume shape factor (f) of from 0.1 to π / 6.
Preferably 50,000 to 50,000 / m on the surface of the coating layer C
m ² , more preferably 0.75 to 40,000 pieces / mm ² ,
It is particularly preferred that the content is such that the projections are formed at a frequency of 10,000 to 30,000 / mm ² . It is preferable that the inert particles A forming the projections have an agglomeration ratio of less than 20%. It is preferable that the agglomeration rate is larger than 0%. Due to the formation of the surface projections, the effect of the present invention becomes more remarkable.

Here, the volume shape factor is given by the following equation (3).
Is defined by

[0045]

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

The shape whose volume shape factor (f) is π / 6 is a sphere (true sphere). Therefore, those having a volume shape factor (f) of 0.4 to π / 6 include substantially spheres, true spheres and elliptical spheres such as rugby balls, and these are particularly preferable.

In the present invention, the total thickness of the laminated film is
Usually 2.5 to 20 μm, preferably 3.0 to 10 μm,
More preferably, it is 4.0 to 10 μm. The layer thickness of the thermoplastic resin layer B is 以下 or less of the total thickness of the laminated film,
Further, it is preferably 1/3 or less, particularly preferably 1/4 or less. The coating layer C has a thickness of 1 to 100 nm,
It is preferably from 50 to 50 nm, particularly preferably from 3 to 10 nm, particularly preferably from 3 to 8 nm.

The laminated film of the present invention can be manufactured by a conventionally known method or a method accumulated in the art. Among them, the laminated structure of the thermoplastic resin layer A and the thermoplastic resin layer B is preferably manufactured by a co-extrusion method, and the lamination of the coating layer C is preferably performed by a coating method.

For example, in the case of a biaxially oriented polyester film, the polyester A and the inert particles B are contained in an extrusion die or before the die (generally, the former is called a multi-manifold type, and the latter is called a feed block type). Polyester B is laminated and composited in a molten state to form a laminated structure having the above-mentioned preferred thickness ratio, and then coextruded from a die into a film at a melting point of Tm ° C to (Tm + 70) ° C. Quenched and solidified by a cooling roll to obtain an unstretched laminated film. Thereafter, the unstretched laminated film is uniaxially (longitudinal or transverse) (T
g-10) to (Tg + 70) ° C. (Tg: glass transition temperature of the polyester) at a magnification of 2.5 to 8.0 times, and preferably at a magnification of 3.0 to 7.5 times. And
Next, in a direction perpendicular to the above direction, Tg to (Tg + 70) ° C.
2.5 to 8.0 times magnification at temperature, preferably 3.0 to 8.0
Stretch at 7.5 times magnification. Further, if necessary, the film may be stretched again in the machine direction and / or the cross direction. That is, two stages, three
It is preferable to perform stretching in multiple stages, four stages, or multiple stages. The total stretching ratio is usually 9 times or more, preferably 12 times or more, as the area stretching ratio.
It is up to 35 times, more preferably 15 to 30 times. Subsequently, the biaxially oriented film is moved from (Tg + 70) to (Tm
Heat setting crystallization at a temperature of -10) ° C, for example, 180 to 250 ° C, provides excellent dimensional stability.
The heat fixing time is preferably 1 to 60 seconds.

In the above method, the above-mentioned inert particles C
And a coating liquid containing a binder resin, preferably an aqueous coating liquid. The application is preferably performed on the surface of the polyester A before the final stretching treatment, and after the application, the film is preferably stretched in at least one direction. Before or during this stretching, the coating film is dried. Among them, the coating is preferably performed on an unstretched laminated film or a longitudinally (uniaxially) stretched laminated film, particularly a longitudinally (uniaxially) stretched laminated film. The application method is not particularly limited, for example, a roll coating method,
Die coating method and the like can be mentioned.

The solid content of the above coating liquid, especially the aqueous coating liquid, is 0.2 to 8% by weight, more preferably 0.3 to 6% by weight, especially 0.1 to 8% by weight.
It is preferably 5 to 4% by weight. The coating liquid (preferably an aqueous coating liquid) may optionally contain other components, for example,
Surfactants, stabilizers, dispersants, UV absorbers, thickeners and the like can be added.

The above example is suitable when both thermoplastic resin layers A and B are polyethylene-2,6-naphthalenedicarboxylate or polyethylene terephthalate, but only layer A or only layer B is polyethylene-2, 6-
The same applies to naphthalene dicarboxylate or polyethylene terephthalate.

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 modifier for the molten polymer.

In the present invention, in order to improve various performances such as head touch and running durability as a magnetic recording medium and to achieve thinning at the same time, the Young's modulus of the laminated film must be increased in the vertical and horizontal directions, respectively. 450 kg / mm ² or more, 600 kg / mm ² or more, and further 480 kg / mm
² or more, 680 kg / mm ² or more, especially 550 kg / m
m ² or more, 800kg / mm ² or more, especially 550kg /
mm ² or more, and preferably 1000 kg / mm ² or more. Further, the crystallinity of the polyethylene terephthalate layer is preferably 30 to 50%, and the crystallinity of the polyethylene-2,6-naphthalenedicarboxylate layer is preferably 28 to 38%. If any of them is below the lower limit, the heat shrinkage increases, while if it exceeds the upper limit, the abrasion resistance of the film deteriorates and white powder is liable to be generated when the film slides on the roll or guide pin surface.

The laminated film of the present invention has a ferromagnetic film composed of iron, cobalt, chromium or an alloy or oxide containing these as a main component on the surface of the coating layer C by a method such as vacuum deposition, sputtering, or ion plating. A metal thin film layer is formed, and on its surface, a protective layer such as diamond-like carbon (DLC),
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 B side, the output in the short wavelength region, the electromagnetic conversion characteristics such as S / N, C / N, etc. It is possible to provide a vapor-deposited magnetic recording medium for high-density recording which has excellent dropout and low error rate. This evaporation type electromagnetic recording medium is an analog signal recording H
i8, digital video cassette recorder (DVC) for recording digital signals, data 8 mm, very useful as a tape medium for DDSIV.

The laminated film of the present invention further comprises a coating layer C
On the surface of, iron or iron-like fine magnetic powder containing iron as a main component is uniformly dispersed in a binder such as polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, and the magnetic layer thickness is 1 μm or less, preferably 0.1 μm or less. １1 μm, and further providing a back coat layer on the surface of the thermoplastic resin layer B side by a known method, so that output in a short wavelength region, S
A metal-coated magnetic recording medium for high-density recording with excellent electromagnetic conversion characteristics such as / N, C / N, and low dropout and error rate. If necessary, a nonmagnetic layer containing fine titanium oxide particles or the like is dispersed and coated in the same organic binder as the magnetic layer as an underlayer of the metal powder-containing magnetic layer on the layer A. You can also. This metal coated magnetic recording medium is used for recording analog signals.
Millivideo, Hi8, β cam SP, W-VHS, digital video cassette coder for digital signal recording (D
VC), data 8mm, DDSIV, digital β cam,
It is extremely useful as a tape medium for D2, D3, SX and the like.

The laminated film of the present invention further comprises a coating layer C
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 polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, and coated 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 surface of the thermoplastic resin layer B side by a known method, output in a short wavelength region, S / N, C
/ N or the like, and can be a coated magnetic recording medium for high-density recording with low dropout and error rate. If necessary, a nonmagnetic layer containing fine titanium oxide particles or the like is dispersed and coated in the same organic binder as the magnetic layer as an underlayer of the metal powder-containing magnetic layer on the layer A. You can 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 a VTR for recording an analog HDTV signal, and DVC is a digital HDTV signal.
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.

[0059]

The present invention will be described below in more detail with reference to examples. The measuring method used in the present invention is as follows.

(1) Intrinsic viscosity Determined from the value measured at 35 ° C. in an orthochlorophenol solvent.

(2) Average particle diameter I of particles (average particle diameter: 0.1
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).

(3) Average particle size II of particles (average particle size: 0.
The particles having an average particle diameter of less than 0.06 μm forming small projections are:
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.

(4) Volume Shape Factor f A photograph of each particle was taken with a scanning electron microscope at a magnification corresponding to the size used, and the maximum diameter of the projected surface was measured using an image analysis processor Luzex 500 (manufactured by Nippon Regulator). And the volume of the particles are calculated by the following equation.

[0064]

Equation 14] f = V / D ³ wherein, f is the volume shape factor, V is the particle volume ([mu] m ^3),
D represents the maximum diameter (μm) of the projection surface.

(5) Frequency of Projection on Film Surface The frequency of projection on the film surface is measured by a scanning electron microscope. That is, a photograph of the surface of the laminated film was taken at a magnification of 5000.
Twenty-five images were taken at 1 × or 10000 ×, the frequency of surface protrusions was counted, and the average value was converted into the number of protrusions per 1 mm ² .

(6) Layer Thickness 1) Thickness of Thermoplastic Resin Layers A and B and Total Thickness The total thickness of the film is randomly measured at 10 points with a micrometer, and the average value is used. The thicknesses of the layers A and B are determined by measuring the layer thickness on the thin side by the method described below, and the layer thickness on the thick side is obtained by subtracting the thickness of the coating layer and the layer on the thin side from the entire thickness. That is, using a secondary ion mass spectrometer (SIMS), the concentration of the element resulting from the highest concentration of particles in the film having a depth of 5000 nm from the surface layer excluding the coating layer and the carbon element of the polyester. The ratio (M ⁺ / C ⁺ ) is defined as the particle concentration and the depth from the surface is 50
Analysis in the thickness direction is performed up to 00 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, in the former case, (stable value 1 + stable value 2) / 2
And, in the latter case, the depth at which the particle concentration is の of the stable value 1 (this depth is deeper than the depth at which the stable value 1 is given), and And

The measurement conditions are as follows.

Measurement device Secondary ion mass spectrometer (SIMS); PERKIN
ELMER 6300 Measurement conditions Primary ion species: O ₂ + Primary ion accelerating 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 : 0.5 KV-3.0 A When the particles most contained in the range of 5000 nm from the surface layer are organic polymer particles other than 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.

2) Thickness of coating layer C A small piece of the film is fixedly formed with an epoxy resin, and an ultra-thin section (cut in parallel to the film flow direction) having a thickness of about 600 angstroms is formed with a microtome.
This sample was subjected to a transmission electron microscope (H-80 manufactured by Hitachi, Ltd.).
(Type 0) and the thickness of the coating layer is determined by searching for the boundary surface of the coating layer C.

(7) Center-surface average roughness A measuring magnification of 40 times and a measuring area of 242 μm × 239 μ were measured using a non-contact three-dimensional roughness meter (TOPO-3D) manufactured by WRa WYKO.
The measurement is performed under the condition of m (0.058 mm ² ), and from the surface analysis by the same roughness system built-in software, WRa uses the value calculated and output by the following equation.

[0071]

(Equation 15)

Z _jk is divided into M in the measurement direction (242 μm) and the direction (239 μm) perpendicular thereto,
The height on the three-dimensional roughness chart at the j-th and k-th positions in each direction when divided.

(8) Young's Modulus Using a tensile tester manufactured by Toyo Baldwin Co., Ltd., a sample film having a length of 300 mm and a width of 12.7 mm was prepared in a room adjusted to a temperature of 20 ° C. and a humidity of 50%. It is pulled at a strain rate of 10% / min, and is calculated by the following equation using the first straight line portion of the tensile stress-strain curve.

[0074]

E = Δσ / Δε where E is Young's modulus (kg / mm ² ), Δσ is a stress difference due to the original average sectional area between two points on the straight line, and Δε is the same 2
It is the strain difference between points.

(9) Abrasion resistance The measurement is carried out as follows using the apparatus shown in FIG. FIG.
Among them, 1 is an unwinding reel, 2 is a tension controller, 3, 5, 6, and 8 are free rollers, 4 is a tension detector, 7 is a blade (a blade for an industrial razor testing machine manufactured by GKI, USA), and 9 is a guide roller. Reference numerals 10 and 10 respectively indicate take-up reels.

A sample film slit to a 1/2 inch width was run at 100 g under a tension of 100 g and a running speed of 100 m / min for 100 m at an angle of 6 degrees against the blade edge, and the cutting ability was determined by the amount of shaving powder adhering to the blade edge. To evaluate.

This evaluation corresponds well to the generation of shavings on guide rolls, nip rolls and the like during the film forming process.

A: The width of the shaving powder adhering to the blade tip is 0.2 mm
Less than ○: The width of the shaving powder adhering to the blade tip is 0.2 mm
Above and less than 1.0 mm ×: The width of the shaving powder adhering to the blade tip is 1.0 mm
that's all

(10) Winding property After optimizing the winding conditions at the time of slitting, the width is 600 mm ×
A roll having a size of 1500 m is slit into 10 rolls, and the occurrence of bumps (having a size of 1 mm or more) on the roll surface immediately after is visually observed, and the winding property is evaluated based on the following criteria. Judgment criteria Number of bumps (total width of roll, per circumference) ◎ 0 to 10 ○ 11 to 30 × 31 to 100 ×× 101 or more

(11) Rz, Ra by atomic force microscope
Measurement of Digital Instruments Atomic Force Microscope (AFM) N
Using an Scope II, an area of 2 μm × 2 μm is measured five times with 256 lines × 256 pixels, and
The average values of the calculated Rz (center plane average roughness) and Ra (center plane average roughness) are defined as measured values.

(12) Production of Magnetic Tape and Characteristic Evaluation A 100% cobalt ferromagnetic thin film was formed on the surface of the coating layer C of the biaxially oriented laminated film by a vacuum evaporation method at 0.02 μm.
2 layers (each layer thickness about 0.1 μm) are formed to have a thickness of about 0.1 μm, and a diamond-like carbon (DLC)
A film and a fluorine-containing carboxylic acid-based lubricating layer are sequentially provided, and a back coat layer is further provided on the surface of the thermoplastic resin B side by a known method. Then, slit into 8mm width, commercially available 8mm
Load on video cassette. Next, the properties of the tape are measured using the following commercially available equipment.

Equipment used: 8 mm video tape recorder Sony Corporation EDV-6000 C / N measurement: Shibasoku Corporation noise meter C / N measurement Recording a signal with a recording wavelength of 0.5 μm (frequency about 7.4 MHz) The ratio between the 6.4 MHz and 7.4 MHz values of the reproduced signal is defined as the C / N of the tape, and the C / N of the commercially available 8 mm video tape is defined as 0 dB.

[0083]

Running Durability A video signal of 4.2 MHz was recorded on the above-mentioned vapor-deposited tape, and the tape running speed was 41 m / 25 ° C. and 50% RH.
And a rewinding speed of 41 m / min.
The output fluctuation after repeating 00 times is examined. Judgment is made based on the output fluctuation based on the following criteria.

A: Output fluctuation after 200 repetitions is 0 dB to -0.3
Less than dB ○: Output fluctuation after 200 repetitions is -0.3 dB to-
Less than 0.6 dB ×: Output fluctuation after -200 repetitions is -0.6 dB or more

Example 1 Dimethyl terephthalate and ethylene glycol, magnesium acetate as a transesterification catalyst, titanium trimellitate as a polymerization catalyst, phosphorous acid as a stabilizer, and inert particles shown in Table 1 as a lubricant And polymerized in a conventional manner to give an intrinsic viscosity of 0.1.
Polyethylene terephthalate (PET) (resin A and resin B, respectively) for layer A and layer B was obtained.

The resin A and the resin B were dried at 170 ° C. for 3 hours, respectively, supplied to two extruders, and melted at a melting temperature of 28 ° C.
The resin layer was melted at 0 to 300 ° C., a resin layer B was laminated on one side of the resin layer A using a multi-manifold type coextrusion die, and rapidly cooled to obtain an unstretched laminated film having a thickness of 87 μm.

The obtained unstretched film is preheated, and is further separated between low-speed and high-speed rolls at a film temperature of 100 ° C. by 3.3.
Aqueous coating solution containing the binder resin and particles C shown in Table 2 (total solid content: 1.0% by weight, HLB value of 1 as a surfactant) was applied to the layer A side of the longitudinally stretched film.
7.1 polyoxyethylene nonyl phenyl ether (containing 18% by weight of the total solid content) was applied by a kiss coat method, subsequently supplied to a stenter, and stretched 4.2 times in the transverse direction at 110 ° C. The obtained biaxially stretched film was
It was heat-set with hot air of 0 ° C. for 4 seconds to obtain a laminated biaxially oriented polyester film having a thickness of 6.3 μm. The thicknesses of the layers A and B were adjusted by the discharge rates of the two extruders. Young's modulus of the film is longitudinally 500 kg / mm ^2, it was transverse 700 kg / mm ^2.

Table 3 shows the surface characteristics, abrasion resistance and winding property of the laminated biaxially oriented film, and the characteristics of a magnetic tape deposited with a ferromagnetic thin film using this film.

[Example 2, Comparative Examples 1 to 3] The procedure was performed except that the particles of the coating layer C, the particles contained in the thermoplastic resin particle layers A and B, and the layer thickness were changed as shown in Tables 1 and 2. In the same manner as in Example 1, a laminated biaxially oriented polyester film was obtained.

Table 3 shows the characteristics of the films thus obtained and the characteristics of the magnetic tape deposited with a ferromagnetic thin film using these films.

Examples 3-5, Comparative Examples 4-5 The same procedures as in Example 1 were carried out except that the particles shown in Table 1 were used and dimethyl 2,6-naphthalenedicarboxylate was used in the same molar amount instead of dimethyl terephthalate. Polyethylene-2,6-naphthalate (PEN) (resin A, resin B) for layers A and B was obtained in the same manner.

After the resin A and the resin B were dried at 170 ° C. for 6 hours, the thickness of each layer was adjusted in the same manner as in Example 1 to obtain an unstretched laminated film satisfying each of Examples and Comparative Examples.

The unstretched film obtained in this way is preheated, and a film temperature of 135 is applied between low-speed and high-speed rolls.
The film was stretched 3.6 times at ℃, quenched, and then an aqueous coating solution of the coating layer C shown in Table 2 was applied in the same manner as in Example 1 and subsequently supplied to a stenter, and then fed at 155 ° C. Stretched 6.0 times. The obtained biaxially stretched film was heat-set with hot air at 200 ° C. for 4 seconds to obtain a laminated biaxially oriented polyester film having a thickness of 4.6 μm. The Young's modulus of these films is 560 kg / mm ^{2 in} the vertical direction and 1100 kg / mm in the horizontal direction.
^{Was 2} . However, in Comparative Example 5, the coating layer C was not provided.

Table 3 shows the surface characteristics, abrasion resistance and winding properties of the laminated biaxially oriented film and the characteristics of a magnetic tape deposited with a ferromagnetic thin film using the film.

[0096]

[Table 1]

[0097]

[Table 2]

[0098]

[Table 3]

As is clear from Table 3, the laminated film according to the present invention has an extremely flat one side and excellent electromagnetic conversion characteristics, and has no rough surface transfer. There is no characteristic difference in the case of using, and it is excellent in abrasion resistance, winding property and running durability. On the other hand, those which do not satisfy the requirements of the present invention cannot simultaneously satisfy these characteristics.

[0100]

According to the present invention, there is provided a high-density magnetic recording medium which is excellent in winding property, easy sliding property and handling property, and excellent in electromagnetic characteristics, dropout, running property of a magnetic layer and durability. Laminated films useful for use can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view of an abrasion resistance measuring device.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-73409 (JP, A) JP-A-5-2772 (JP, A) JP-A-7-246689 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (16)

(57) [Claims] 1. A thermoplastic resin layer B containing inert particles B is laminated on one surface of a thermoplastic resin layer A, and a coating layer C is applied on the other surface of the thermoplastic resin layer A. Laminated film, wherein the thermoplastic resin layer B
Average particle size of the largest particle among the contained inert particles B
d _B is at 0.1 to 1 [mu] m, 0.001 to its content C _B
0.5 wt%, the layer thickness t _B of the thermoplastic resin layer B
(Nm), the average particle size d _B (μm) of the largest particles among the inert particles B and the content C _B (% by weight) satisfy the following expression (1), and Atomic force microscope (A
A laminated film, characterized in that the center plane ten-point average roughness Rz (nm) and the center plane average roughness Ra (nm) measured by FM) satisfy the following expression (2). [Number 1] ^{_{0.1 ≦ (d B) 3 ×}} C B × t B ≦ 10 ······ (1) Equation 2] 8 ≦ Rz / Ra ≦ 40 ······ (2) 2. The thickness t _B (nm) of the thermoplastic resin layer B
And the average particle diameter d of the largest particle among the inert particles B
_B (μm) and the content C _B (% by weight) of the following formula (1)
The laminated film according to claim 1, which satisfies -1). Equation 3] ^{_{0.2 ≦ (d B) 3 ×}} C B × t B ≦ 8 ······ (1-1) 3. An atomic force microscope ( AFM ) of the coating layer C.
2. The laminated film according to claim 1, wherein the center plane ten-point average roughness Rz (nm) and the center plane average roughness Ra (nm) satisfy the following expression (2-1). [Expression 4] 12 ≦ Rz / Ra ≦ 36 (2-1) 4. A center plane average roughness WR of the thermoplastic resin layer B.
a ^B is less than 5nm or more 0.5nm and coating layer C center plane average roughness WRa ^C greater claim 1 or laminate film according to the second. 5. The coating layer C contains inactive particles C having an average particle size of 10 to 50 nm in such an amount as to form fine projections on the surface of the layer C at a frequency of 2,000,000 to 20,000,000 particles / mm ^2. 4. The laminated film according to 1 or 3. 6. The coating layer C has a thickness of 1 to 100 nm.
A laminated film according to claim 1, 3 or 5. 7. The thermoplastic resin layer A has an average particle size of 40 to 4
Inactive particles A having a volume shape factor of 0.1 to π / 6
^2. The laminated film according to claim 1, wherein the coating film has an amount of 50,000 to 50,000 protrusions / mm ² at the surface of the coating layer C. 8. The laminated film according to claim 7, wherein the particle aggregation rate of the inert particles A is less than 20%. 9. The laminated film according to claim 1 , wherein the thickness of the thermoplastic resin layer B is 以下 or less of the total thickness of the laminated film. 10. The total thickness of the laminated film is 2.5 to 20.
The laminated film according to any one of claims 1 to 9, wherein the thickness is μm. 11. The laminated film according to claim 1, wherein the thermoplastic resins of the layers A and B are each an aromatic polyester. 12. The laminated film according to claim 11, wherein the aromatic polyester is polyethylene terephthalate or polyethylene 2,6-naphthalenedicarboxylate. 13. The laminated film according to claim 1, which is a base film of a magnetic recording medium. 14. The laminated film according to claim 13, wherein the magnetic recording medium is a metal thin film type magnetic recording medium. 15. The magnetic recording medium according to claim 1, wherein the thickness of the magnetic layer is 1 μm.
The laminated film according to claim 13, which is the following coating type magnetic recording medium. 16. The laminated film according to claim 13, wherein the magnetic recording medium is a digital signal recording type magnetic recording medium.