JP3200349B2 - 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 an excellent winding property, no defect, easy sliding and handling, especially electromagnetic characteristics, dropout, running property of a magnetic layer surface, and durability. The present invention relates to a laminated film useful as a base film of a magnetic recording medium having excellent properties.

[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-described 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.

On the other hand, from the viewpoint of handling such as film formation of a non-magnetic support (base film), transportation, scratching, winding and unwinding in the film forming process, if the film surface is too smooth, the film-film mutual The slipperiness of the material 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, it is desirable that the surface of the non-magnetic support (base film) is as rough as possible from the viewpoint of manufacturing cost.

As described above, the surface of the nonmagnetic 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.

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 coating and forming a continuous film having fine irregularities on the film surface (Japanese Patent Laid-Open No. 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-described method of applying a discontinuous film or a continuous film having fine irregularities by coating, the problems such as film-to-film slip and blocking can be solved. In terms of handling such as film formation, transportation, scratching, winding and unwinding in the film forming process, from the viewpoint of product yield and product cost, the base film for high density and large capacity magnetic recording media There are problems with the application. Similar problems also exist in the conventional coextrusion technique or in the technique of combining the coextrusion technique with a discontinuous film or a continuous film. Further, in the case of a metal thin film type magnetic recording medium, there still remains a problem of running properties under high temperature and high humidity conditions.

An object of the present invention is to solve the drawbacks of the prior art and provide a laminated film having excellent transportability, scratch resistance and winding property in a film forming process, and a metal thin film having these characteristics. Another object of the present invention is to provide an inexpensive biaxially oriented laminated film for a high-density magnetic recording medium which has excellent running properties under high-temperature and high-humidity conditions even when used as a type-type magnetic recording medium.

[0012]

According to the present invention, first, according to the present invention, firstly, one side of a thermoplastic resin layer A substantially free of inert particles having an average particle diameter of 40 nm or more is coated on one side. A thermoplastic resin layer B containing active particles and having a rougher surface than the thermoplastic resin layer A is laminated, and the total thickness is 3.0.
A biaxially oriented laminated film having a thickness of 10 μm to 10 μm, wherein the surface of the thermoplastic resin layer A is 0 ± 10 mm with respect to the longitudinal direction of the film.
In the direction of 10 degrees, height 2 to 85 nm, average width 20 to 50
This is achieved by a laminated film characterized by having undulations of 0 μm at a frequency of ⁴ to 2500 protrusions / mm ² .

[0013] Examples of the thermoplastic resin in the present invention include polyester resins, polyamide resins, polyimide resins, polyether resins, polycarbonate resins, polyvinyl resins, polyolefin resins, and the like. Of these, polyester resins and aromatic polyesters are preferred.

As the aromatic polyester, polyethylene terephthalate, polyethylene isophthalate,
Preferable examples include polytetramethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate, and polyethylene-2,6-naphthalenedicarboxylate. 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%.

Furthermore, 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.

In the present invention, the biaxially oriented laminated film has a thermoplastic resin layer A and a thermoplastic resin layer B, but the thermoplastic resins of the layers A and B may be the same or different.
Among them, the same resin is preferable. In particular, layer A and layer B are polyethylene terephthalate or polyethylene
It preferably comprises 2,6-naphthalenedicarboxylate.

The biaxially oriented laminated film in the present invention comprises:
It has a flat surface layer (that is, the thermoplastic resin layer A) and a rough surface layer (that is, the thermoplastic resin layer B). Then, a coating layer C can be provided on a surface of the thermoplastic resin B which is not in contact with the layer A, if necessary. If necessary, it is also possible to provide a thin coating layer on the surface of the thermoplastic resin layer A that is not in contact with the layer B as long as the effect of the present invention is not impaired.

This thermoplastic resin layer A has an average particle size of 40
nm or more, preferably 10 nm or more, more preferably 5 nm or more.
The particles do not substantially contain inert particles having a height of 2 to 85 nm, preferably 2 to 50 nm, more preferably 2 to 50 nm, in a roughness profile measured in the direction of 0 ± 10 degrees with respect to the longitudinal direction of the film on the surface. Is 2 to 25 nm, average width is 20 to 500 μm, preferably 20 to 300 μm,
More preferably, the number of undulations of 20 to 200 μm is 4 to
2500 pieces / mm ² , preferably 10 to 2000 pieces / m
m ² , more preferably 10 to 2000 / mm ² .

When the undulations have a height of less than 2 nm or a width of more than 500 μm, the undulations may be transported in the film forming process.
The film is insufficient in terms of scratching of the film, winding of the product roll, blocking phenomenon between film and film, and running property of the tape under high-temperature and high-humidity conditions when used for metal thin film magnetic recording.

On the other hand, if the height of the undulations exceeds 85 μm, the electromagnetic conversion characteristics will be impaired, and it is not suitable as a base film for a high-density magnetic recording medium. If the average width of the undulations is less than 20 μm, the transportability in the film forming process and the tape running property become insufficient in the region where the height of the undulations is 25 nm or less.

The direction of measurement of the undulations is 0 ± 10 degrees with respect to the longitudinal direction of the film, which is the same as that of a magnetic recording system to which a high-density magnetic recording tape using a base film according to the present invention is applied. By aligning the track on the tape with the track scanned by the magnetic head.

The undulating protrusions in the thermoplastic resin layer A are not restricted by the method of forming the undulations, but are caused by the pushing-up action of the layer A accompanying the stretching of the inert particles contained in the thermoplastic resin layer B. Is preferred.

In order to exhibit this pushing-up action more efficiently, it is preferable that the average particle size of the inert particles and the thickness of the thermoplastic resin layer A satisfy a specific relationship.
That is, the inert particles in the thermoplastic resin layer B consist of single particles or two or more types of particles having different sizes, and the average particle size of the single particles or the average particle size of the largest particle of the two or more types of particles. was a d _B (μm), the thickness of the layer a t _a (mu
m), the following equation 1

[0025]

[Number 2] preferably set to _{4 ≦ t A / d B ≦} 25 as to satisfy the ...... 1. This t _A / d _B
Furthermore, it is preferably from 4 to 16, particularly preferably from 4 to 8.

The thermoplastic resin layer A according to the present invention further has a surface roughness of 1 mm in center plane average roughness (WRa ^A ).
It is preferably at most 0 nm, more preferably at most 5 nm, particularly preferably at most 2 nm, especially preferably at most 1 nm. If the surface roughness is too rough, the electromagnetic conversion characteristics and the like decrease, which is not preferable.

In the present invention, the thermoplastic resin layer B forming a rough surface contains inert particles as described above. This surface has a surface roughness greater than that of the thermoplastic resin layer A. In other words, the center plane average roughness WRa ^B of the thermoplastic resin layer ^B and the center plane average roughness WR of the thermoplastic resin layer A
the following formula 2 and a ^A

[0028]

WRa ^B > WRa ^A ... 2 Here, WRa ^A and WRa ^B are non-contact three-dimensional center plane average roughnesses measured on the outer surfaces of the thermoplastic resin layers A and B, respectively. To be satisfied. WRa ^B is preferably at least 1 nm, more preferably at least 1.5 nm larger than WRa ^A. The center plane average roughness WRa ^B is preferably 2 nm or more and less than 15 nm, more preferably 3 to 10 nm, and particularly preferably 3 to 7 nm.

The surface roughness WRa ^B of the thermoplastic resin layer ^B is 1
If it is 5 nm or more, it is difficult for the height and average width of the undulating protrusions on the surface of the thermoplastic resin layer A to satisfy the above-mentioned requirements, and if it is less than 2 nm, handling properties such as transportability, tape running properties, etc. Insufficient and undesirable. Further W
When Ra ^B is less than WRa ^A , the flatness deteriorates handling properties such as transport, scratching, winding and unwinding in the base film forming process.
The blocking phenomenon occurs due to the deterioration of the slipperiness between the films, the shape when rolled (roll formation) deteriorates, the productivity decreases, the product yield decreases,
As a result, the production cost of the product is increased, which is not preferable.

In order to impart the above-mentioned surface characteristics to the thermoplastic resin layer B and to make the thermoplastic resin layer A exhibit the above-mentioned undulations, the average particle diameter dB of the inert particles in the layer _B is as follows: 0.2-1 μm, further 0.2-0.8 μm, especially 0.2
It is preferably about 0.6 μm. The average particle diameter d _B
Means the average particle diameter when the inert particles consist of single particles, and the average particle diameter of the largest particle among these particles when the inert particles consist of two or more kinds of particles having different sizes.

Examples of the inert particles having an average particle diameter d _B, crosslinked silicone resin, crosslinked polystyrene, crosslinked styrene - divinylbenzene copolymer, polymethyl methacrylate, methyl methacrylate copolymers, crosslinked methyl methacrylate copolymer, Fine particles made of a heat-resistant organic polymer such as polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, benzoguanamine resin, silica, alumina, titanium dioxide, kaolin, talc, graphite, calcium carbonate, feldspar,
Any of fine particles made of an inorganic compound such as molybdenum disulfide, carbon black, barium sulfate and the like may be used. Among these, particles having a volume shape factor of 0.4 to π / 6 are preferred.

The thermoplastic resin layer B, the average particle diameter d _B
One or more particles having a small average particle size can be contained in addition to the particles having the following. And in this case, the second and third
As particles having a small average particle diameter of 0.01 μm or more.
Fine particles of 1 μm or less, for example, colloidal silica, α,
Fine particles such as alumina having crystal forms such as γ, δ, and θ can be preferably used. It can also be used an average particle size of 0.01μm or more 0.1μm or less fine particles of those exemplified as the inert particles having an average particle diameter d _B.

The content of these inert particles is 0.001 to
It is preferably 5.0% by weight, more preferably 0.005 to 1.0% by weight, particularly preferably 0.01 to 0.5% by weight.

In the present invention, the total thickness of the laminated film is
It is 3.0 to 10 μm, preferably 4.0 to 10 μm. The thickness construction of the flat layer A and the rough surface layer B, so that the wavy protrusions on the surface of the flat layer A occurs, an average particle diameter d _B and the flat layer A of the inert particles added to Somenso B _A suitable thickness is set based on the layer thickness tA. The thickness t _A of the flat layer A is 0.8 μm
not less than m, also of the rough surface layer B thickness t _B is in the layer B
The above half the average particle diameter d _B of the inert particles ([mu] m)
It is preferred that

The laminated film of the present invention can be produced by a conventionally known method or a method accumulated in the art. Among them, it is preferable to produce by a co-extrusion method. For example, in the case of a biaxially oriented polyester film, a coarse layer containing the above-described flat layer polyester A and inert particles in or before the extrusion die (generally, the former is called a multi-manifold type, and the latter is called a feed block type). The polyester B of the face layer is laminated and composited in a molten state to form a laminated structure having the above-described preferred thickness ratio, and then coextruded into a film at a melting point of Tm ° C. to (Tm + 70) ° C. from a die. Rapidly solidifies at ~ 90 ° C 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.
３５35 times, more preferably 15 to 26 times. Subsequently, the biaxially oriented film is formed 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.

According to this method, a biaxially oriented laminated polyester film having good interlayer adhesion can be obtained.

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%. When the value is below the lower limit, the heat shrinkage rate increases. On the other hand, when the value exceeds the upper limit, the abrasion resistance of the film deteriorates, and white powder is easily generated when the film slides on the roll or the guide pin surface.

The laminated film of the present invention is formed on the thermoplastic resin layer A, that is, on the flat surface side, by a method such as vacuum deposition, sputtering, or ion plating. Alternatively, a ferromagnetic metal thin film layer composed of an oxide is formed, and a protective layer such as diamond-like carbon (DLC) and a fluorinated carboxylic acid-based lubricating layer are sequentially provided on the surface of the ferromagnetic metal thin film layer. By 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. are particularly excellent, and the high density with little dropout and error rate is provided. It can be used as an evaporation type magnetic recording medium for recording. This vapor-deposited electromagnetic recording medium is extremely useful as a Hi8 for analog signal recording, a digital video cassette recorder (DVC) for digital signal recording, an 8 mm data, and a tape medium for DDSIV.

The laminated film of the present invention is also characterized in that the thermoplastic resin layer A, that is, the needle-like fine magnetic powder containing iron as a main component is coated on the thermoplastic resin layer A, that is, on the flat surface side, with vinyl chloride, vinyl chloride / vinyl acetate copolymer. Etc., uniformly dispersed in a binder, and applied so that the magnetic layer thickness is 1 μm or less, preferably 0.1 to 1 μm, and further provided a back coat layer on the surface of the thermoplastic resin layer B side by a known method. In particular, the output in the short wavelength region, and excellent electromagnetic conversion characteristics such as S / N and C / N,
A metal-coated magnetic recording medium for high-density recording with low dropout and error rate can be obtained. If necessary, a nonmagnetic layer containing fine titanium oxide particles or the like may be dispersed and coated on the layer A in the same organic binder as the magnetic layer as an underlayer of the metal powder-containing magnetic layer. Can also. This metal-coated magnetic recording medium is an 8 mm video for analog signal recording, Hi8, β cam SP, W-VH
It is very useful as a tape medium for S, digital video cassette coder (DVC) for recording digital signals, data 8 mm, DDSIV, digital β cam, D2, D3, SX, etc.

The laminated film of the present invention also comprises a thermoplastic resin layer A, that is, a flat fine magnetic powder such as iron oxide or chromium oxide, or a plate-like fine magnetic powder such as barium ferrite on the flat surface. Uniformly dispersed in a binder such as vinyl, vinyl chloride / vinyl acetate copolymer, and applied so that the thickness of the magnetic layer is 1 μm or less, preferably 0.1 to 1 μm, and further known to the surface of the thermoplastic resin layer B side. The coating magnetic recording medium for high-density recording is particularly excellent in output in the short wavelength region, excellent in electromagnetic conversion characteristics such as S / N and C / N, and has low dropout and error rate by providing the back coat layer by the method of (1). It can be. If necessary, a nonmagnetic layer containing fine titanium oxide particles or the like may be dispersed and coated on the layer A in the same organic binder as the magnetic layer as an underlayer of the metal powder-containing magnetic layer. You can also. 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 for recording a TV signal, and the film of the present invention can be said to be a very useful base film for these magnetic recording media for HDTV-compatible VTRs.

[0044]

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 a 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: 0.1
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 is taken with a scanning electron microscope at a magnification corresponding to the size used, and the maximum diameter of the projected surface is measured using an image analysis processing device Luzex 500 (manufactured by Nippon Regulator). And the volume of the particles are calculated by the following equation.

[0049]

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.

(5) Layer Thickness The total thickness of the film is randomly 10 micrometers by a micrometer.
Measure the points and use the average value. The layer thickness is obtained by measuring the layer thickness on the thinner side by the method described below, and subtracting the layer thickness on the thicker side from the layer thickness on the thinner side than the total thickness. That is, using a secondary ion mass spectrometer (SIMS), the concentration ratio (M ⁺ /) of the element resulting from the highest concentration of 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.

(6) Undulating protrusions on the film surface Using a non-contact three-dimensional roughness tester (TOPO-3D) manufactured by WYKO, a measurement magnification of 40 times and a measuring area are used according to the size and height of the undulating projections. 234 μm × 240 μm (0.056
mm ² ) or measuring magnification 10 times, measuring area 956 μm ×
Measurement is performed at 980 μm (0.937 mm ² ), and the undulation height and average width are read from the obtained three-dimensional roughness chart. The measurement was performed on a sample cut in a direction of 5 to 10 degrees with respect to the longitudinal direction of the film.

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

[0054]

(Equation 5)

Further, Z _jk is divided into M in the measurement direction (242 μm) and the direction (239 μm) perpendicular thereto, respectively.
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 Tensilon manufactured by Toyo Baldwin Co., in a room adjusted to a temperature of 20 ° C. and a humidity of 50%, a sample film having a length of 300 mm and a width of 12.7 mm was prepared. 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.

[0057]

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

(9) Winding properties After optimizing the winding conditions at the time of slitting, the width is 560 mm ×
After a slit of 10 rolls having a size of 9000 m, the rollability is evaluated based on the following criteria based on the number of rolls that can be commercialized according to the state of film wrinkling after leaving for one week.

[0059]

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

Equipment used: 8mm video tape recorder Sony Corporation EDV-6000 C / N measurement: Shibasoku Corporation noise meter

C / N Measurement A signal having a recording wavelength of 0.5 μm (frequency of about 7.4 MHz) is recorded, and the ratio of the value of the reproduced signal between 6.4 MHz and 7.4 MHz is defined as the C / N of the tape. The C / N of the 8 mm video evaporation tape is represented by OdB and expressed as a relative value. Running property under high temperature and high humidity When the tape is continuously played back under high temperature and high humidity of 50 ° C. and 80% RH, the reproduced image is observed, and it is determined whether or not the image fluctuates.

(11) Scratch of film The film was sampled from the final product roll after slitting, and the flat surface side surface was observed with an optical microscope at a magnification of 100 times.
The number of scratches in 20 visual fields is counted. The criteria are as follows.

[0064]

Example 1 Dimethyl terephthalate and ethylene glycol, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, phosphorous acid as a stabilizer, and inerts shown in Tables 1 and 2 as lubricants The particles are added and polymerized by a conventional method to obtain polyethylene terephthalate (PE) for layers A and B having an intrinsic viscosity of 0.60.
T) (resin A and resin B, respectively) were obtained.

Each of the resin A and the resin B was dried at 170 ° C. for 3 hours, and then supplied to two extruders.
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 129 μm.

The obtained unstretched film was preheated, stretched 3.2 times at a film temperature of 95 ° C. between low-speed and high-speed rolls, quenched, and then supplied to a stenter.
The film was stretched 4.1 times in the transverse direction at ℃. The obtained biaxially stretched film was heat-set with hot air of 220 ° C. for 4 seconds, and the thickness was 9.
An 8 μm laminated biaxially oriented polyester film was obtained. The thickness of each layer was adjusted by the discharge amount of two extruders. The Young's modulus of this film is 500 kg /
mm ² , and 700 kg / mm ² in the lateral direction.

[0068] surface properties of the laminated biaxially oriented film, of the inert particles contained in the thickness t _A and the rough surface layer B of the flat layer A, the ratio of the average particle diameter d _B of the largest particles t _A / d _B ,
Table 3 shows the winding properties and the characteristics of the ferromagnetic thin film-deposited magnetic tape using this film.

[Examples 2 and 3, Comparative Examples 1-3, 5] Except that the particles shown in Tables 1 and 2 were used and the layer thicknesses of the rough layer B and the flat layer A were adjusted as shown in Tables 1 and 2. In the same manner as in Example 1, a laminated biaxially oriented polyester film was obtained. However, Comparative Example 5 is a film having a single-layer structure. Table 3 shows the properties of the obtained laminated biaxially oriented films and the properties of the ferromagnetic thin film deposited magnetic tape using these films.

[Examples 4 to 7, Comparative Examples 4 and 6] Tables 1 and 2
And the flat layer A was prepared in the same manner as in Example 1 except that the particles shown in the above were used and dimethyl 2,6-naphthalenedicarboxylate was used in the same molar amount instead of dimethyl terephthalate.
Polyethylene-2,6-naphthalate (P
EN) (resin A and resin B, respectively).

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.
Unstretched laminated films satisfying the respective examples and comparative examples were obtained.
However, Comparative Example 6 is a film having a single-layer structure.

The obtained unstretched film was preheated, and further between a low-speed and high-speed roll at a film temperature of 135 ° C.
The film is stretched 6 times, quenched, and then supplied to a stenter.
It was stretched 6.0 times in the transverse direction at 55 ° C. 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 4.8 μm (however, Comparative Example 6 had a single-layer structure). The Young's modulus of these films is 560 kg / mm ^{2 in} the vertical direction and 1100 k in the horizontal direction.
g / mm ² . However, in Example 6, the vertical magnification was 4.8.
Under the stretching conditions of 5 × width ratio 5.0, the total thickness is 4.8 μm, the Young's modulus is 700 kg / mm ^{2 in} the vertical direction, and 730 kg /
to obtain a film of mm ^2, also longitudinal magnification 4.0 Example 7
X Under the stretching conditions of a horizontal magnification of 5.0, the total thickness is 7.5 μm, the Young's modulus is 600 kg / mm ^{2 in} the vertical direction, and 900 kg /
A film of mm ² was obtained. Table 3 shows the properties of the films thus obtained and the properties of the ferromagnetic thin film-deposited magnetic tape using these films.

As is clear from Table 3, the laminated film according to the present invention is excellent in scratch resistance, very flat on one side and has excellent electromagnetic conversion characteristics, and at the same time does not adversely affect the electromagnetic conversion characteristics. Extremely excellent base due to the effect of both stable running property under high temperature and high humidity as a tape by the effect of having the waviness protrusions of low height and large width, and the effect of both the waviness and the rough surface on the opposite side. It has both winding properties as a film. On the other hand, the conventional technology
These four requirements cannot be satisfied simultaneously.

[0074]

[Table 1]

[0075]

[Table 2]

[0076]

[Table 3]

[0077]

According to the present invention, winding property, defect-free property,
It is possible to provide a laminated film having excellent slipperiness and handling properties, and particularly useful as a base film of a high-density magnetic recording medium having excellent electromagnetic characteristics, dropout, running properties of a magnetic layer, and durability.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-84818 (JP, A) JP-A-4-294124 (JP, A) JP-A-5-77318 (JP, A) JP-A-58-1983 68225 (JP, A) JP-A-4-138251 (JP, A) JP-A-6-114923 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35 / 00 EPAT (QUESTEL) WPI / L (QUESTEL)

Claims (12)

(57) [Claims] 1. A thermoplastic resin layer A substantially free of inactive particles A having an average particle size of 40 nm or more has a surface containing inactive particles and having a rougher surface than the thermoplastic resin layer A. The plastic resin layer B is laminated, and the total thickness is 3.0 to 3.0.
A 10μm der Ru biaxially oriented laminated film, the surface of the thermoplastic resin layer A, 0 ± respect film longitudinally 1
0-degree direction, height 2-85 nm, average width 20-500
A laminated film having undulating protrusions of μm at a frequency of ⁴ to 2500 / mm ² . Wherein the inert particles of the thermoplastic resin layer B is made of a single particle or the size of two or more particles having different average particle size or a single particle an average of the largest particle of two or more particles The laminated film according to claim 1, wherein the particle size and the thickness of the thermoplastic resin layer A satisfy the following formula 1. [Number 1] _{4 ≦ t A / d B ≦} 25 ······ 1 wherein, t _A is the thickness of the thermoplastic resin layer A (μm), d _B is the sole thermoplastic resin layer B It is the average particle diameter (μm) of the particles or the average particle diameter (μm) of the largest particle among two or more kinds of particles. 3. The inert particles in the thermoplastic resin layer B have an average particle diameter of a single particle or an average particle diameter of the largest particle of two or more kinds of particles is 0.2 to 1 μm, and is inert. The content of particles is 0.001 to 5.0% by weight.
Or the laminated film according to 2. 4. The laminated film according to claim 1, wherein the center surface average roughness WRa ^A of the surface of the thermoplastic resin layer ^A is 10 nm or less. 5. The laminated film according to claim 1, wherein the center plane average roughness WRa ^B of the surface of the thermoplastic resin layer ^B is 2 nm or more and less than 15 nm. 6. the thickness of the thermoplastic resin layer A is 0.8μm or more, the thickness of the thermoplastic resin layer B is more than half the <br/> average particle diameter d _B of the inert particles in the layer B laminated fill-beam according to claim 1 or 2 is. 7. The laminated film according to claim 1, wherein each of the thermoplastic resins of the layers A and B is an aromatic polyester. 8. The laminated film according to claim 7 , wherein the aromatic polyester is polyethylene terephthalate or polyethylene-2,6-naphthalenedicarboxylate. 9. The laminated film according to claim 1, which is a base film of a magnetic recording medium. 10. The laminated film according to claim 9 , wherein the magnetic recording medium is a metal thin film type magnetic recording medium. 11. The magnetic recording medium according to claim 1, wherein the thickness of the magnetic layer is 1 μm.
The laminated film according to claim 9 , which is the following coating type magnetic recording medium. 12. The laminated film according to claim 9, wherein the magnetic recording medium is a digital signal recording type magnetic recording medium.