JP2000094382A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film having the good corona treatment blocking resistance, excellent in traveling durability and electromagnetic transforming characteristics even in using it as an evaporation metallic thin film-type magnetic recording medium, and capable of manufacturing a magnetic recording medium having a little drop-out. SOLUTION: This laminated film is composed of a base layer A made of a thermoplastic resin A and a coating layer B existing on the front surface of the base layer A. The coating layer B is a coating film taking water soluble resin or water dispersing resin containing binder resin, inactive particles, a surfactant, silicon or wax of 1 to 50 wt.% as a main material, and corona treatment blocking separating force is not more than 15 g/10 cm.

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 corona blocking resistance, running durability,
The present invention relates to a laminated film having excellent electromagnetic conversion characteristics and being useful as a base film of a magnetic recording medium having extremely small dropout.

[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-film magnetic recording medium in which a needle-shaped magnetic powder such as a metal powder or an iron oxide powder is applied to a thickness of 2 μm or less, has been promoted. As an example of the former, Japanese Patent Application Laid-Open No. 54-147010 discloses that the first Co thin film magnetic layer adhered on a substrate made of a non-magnetic material, C
o A magnetic recording medium in which a second Co thin film magnetic layer having a thickness greater than the thickness of the thin film magnetic layer is disclosed, and Japanese Patent Application Laid-Open No. 52-134706 discloses perpendicular magnetic recording comprising a Co-Cr alloy. A medium is disclosed.

As an example of the latter, a technical report MR94-78 (1995-02) of the Institute of Electronics and Communication Engineers discloses high-density magnetic recording using an extremely thin layer-coated magnetic recording medium.

Conventional coating type magnetic recording media (magnetic recording media in which magnetic powder is mixed with an organic polymer binder and coated on a nonmagnetic 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,
m and are very thin. For this reason, in the high-density magnetic recording medium described above, the surface condition of the non-magnetic support (base film) greatly affects the surface properties of the magnetic layer. The surface state of the magnetic support directly appears as irregularities on the surface of the magnetic layer (magnetic recording layer).

Further, in the case of a metal thin film type magnetic recording medium, a serious problem in actual use is the running property of the metal thin film surface. In the case of a coating type magnetic recording medium in which 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 decrease during repeated use is greater than that of the coating type magnetic recording medium.

In the case of a metal thin film type magnetic recording medium, in order to improve the adhesion between the metal thin film and the base film, the surface of the base film called ion bombardment is activated by ions before forming the metal thin film. Is performed. At the time of forming this metal thin film, high temperature heat is applied to the film surface, and the base film is melted or
Rear cooling is performed so as not to impair the physical properties such as mechanical properties. In many cases, the back surface cooling is performed by winding a base film around a drum-shaped cooling body. At this time, both ends of the base film are masked so that a thin metal film is not formed on the surface of the drum.

Therefore, portions where only the ion bird process is performed and where no metal thin film is formed are continuously generated in the same portion in the longitudinal direction of the film, and are both edges of the roll. When this portion is wound because the surface of the base film is super-flat, the activated base surface comes into contact with the base surface on the opposite side, blocking easily occurs, and a process trouble occurs.

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 a processing step, if the film surface is too smooth, the film-film mutual Slipperiness deteriorates, and here also, a blocking phenomenon occurs, and the shape when rolled (roll formation) deteriorates, resulting in a decrease in product yield and a rise in product manufacturing cost. 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 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 blocking resistance, handling properties, and film cost. In particular, in order to improve the blocking resistance, a rough surface is required to reduce the contact area of the film. Therefore, in order to manufacture a high-density magnetic recording medium of excellent quality, it is necessary to simultaneously satisfy the above two trade-offs.

Japanese Patent Application Laid-Open No. 5-194772 discloses poly
A magnetic film consisting of a continuous thin film on one surface of the ester film
A primer layer for the functional layer
The surface of the continuous thin film of the layer is (A) an average particle size of 0.06 μm or less.
Small protrusions with a height of 13 nm or less and full particles as nuclei (B)
30 n height with particles having an average particle size of 0.06 μm or more as nuclei
m or less of the large protrusions and the resin forming the primer layer (C).
And the number of these protrusions is represented by the following formula A_N≧ 1.0 × 10⁶(Pcs / mm^Two) B_N≧ 1.05 × 10^Four(Pcs / mm^Two) A_N≦ −3.4 × 10^Two・ B_N+ 13.6 × 10⁶(Pcs / m
m^Two) C_N≦ 4.0 × 10⁶(Pcs / mm^Two[However, A_NIs the number of small protrusions (pcs / mm^Two), B_NIs a big bump
Number of pieces (pcs / mm^Two ), C_NIs the number of microprojections (pieces / m
m^Two). And a primer layer is formed
Surface roughness Ra of the continuous thin film part by only the resin^SBut
1.10 nm or less, and the surface roughness of the continuous thin film
A polyester for a magnetic recording medium, wherein Ra is 1 to 10 nm.
A film is disclosed.

Japanese Patent Application Laid-Open No. Hei 5-298670 discloses a poly
A magnetic film consisting of a continuous thin film on one surface of the ester film
A primer layer for the functional layer
(A) Average particle size 0.06 μm
Small projections with a height of 13 nm or less, with the core of particles less than
(B) Height with particles having an average particle diameter of 0.06 μm or more as nuclei
Forms large protrusions of 30 nm or less and (C) primer layer
Small protrusions with a maximum major diameter of 0.30 μm or less made of only resin
Are formed, and the number of these projections is represented by the following formula A_N≧ 1.0 × 10⁶(Pcs / mm^Two) B_N≧ 1.05 × 10^Four(Pcs / mm^Two) A_N≦ −3.4 × 10^Two・ B_N+ 13.6 × 10⁶(Pcs / m
m^Two) C_N≦ 4.0 × 10⁶(Pcs / mm^Two[However, A_NIs the number of small protrusions (pcs / mm^Two), B_NIs a big bump
Number of pieces (pcs / mm^Two ), C_NIs the number of microprojections (pieces / m
m^Two). To form the primer layer.
Surface roughness Ra of the continuous thin film part using only resin^SBut
1.10 nm or less, and the surface roughness of the continuous thin film
Ra is 1 to 10 nm, and the continuous thin film is
When the film is continuously heated in air at 160 ° C for 5 minutes
Precipitation of polyester oligomer microcrystals on film surface
For magnetic recording media that can control the ratio to 0.8% or less
A steal film is disclosed.

According to the polyester film as described above, although the smoothing of the base film on the magnetic layer side can be realized to some extent, the problem of causing dropout due to the presence of the cohesive coarse projections derived from the coating layer is solved. I couldn't. Further, in the above-mentioned method, particles are added to the base film on the magnetic layer surface side in order to improve running durability, but due to poor dispersibility of the particles, there are many coarse projections, and this is a cause of dropout. And the output is lowered due to uneven wear of the magnetic head. Further, even with these treatments, the problem of blocking of the roll edge activated by the ion bombardment treatment could not be solved.

[0013]

An object of the present invention is to provide a laminated film useful as a base film for a magnetic recording medium.

Another object of the present invention is to significantly reduce coarse projections, which are a cause of dropout, derived from a coating solution for forming a coating film layer, have excellent running durability and electromagnetic conversion characteristics, and have extremely few dropouts. Another object of the present invention is to provide a laminated film for providing a magnetic recording medium having good blocking resistance.

Still other objects and advantages of the present invention will become apparent from the following description. According to the present invention, the above objects and advantages of the present invention are achieved by a base layer A made of a thermoplastic resin A and a coating layer B present on one surface of the base layer A.
Wherein the coating layer B comprises a binder resin, inert fine particles and a surfactant, and further contains a water-soluble resin or a water-dispersible resin containing 1 to 50% by weight of either silicone or wax. A coating film mainly composed of a resin, or a water-soluble resin or a water-dispersible resin containing a binder resin, inert fine particles and a surfactant, and further containing 5 to 90% by weight of a polysiloxane copolymerized polyester resin. Corona treatment blocking is achieved by a laminated film characterized by having a peeling force of 15 g / 10 cm or less.

The corona-treated blocking has a peeling force of 15 g.
If it is higher than / 10 cm, cutting due to blocking occurs in the step of using the film. This corona treatment blocking preferably has a cutting force of 10 g / 10 cm or less.

Examples of the thermoplastic resin forming the base layer A include polyester resins, polyamide resins, polyimide resins, polyether resins, polycarbonate resins, polyvinyl resins, and polyolefin 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. It will be understood that copolymer components other than polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate can be considered in the same manner as described above. The polyester is known per se,
And it can be manufactured by a method known per se.

The thermoplastic resin A forming the base layer A is
It may or may not substantially contain inert fine particles. When containing inert fine particles, the inert fine particles are preferably inert fine particles A having an average particle diameter of 30 to 400 nm and a volume shape factor of 0.1 to π / 6. The average particle size is more preferably from 40 to 200 nm, particularly preferably from 60 to 120 nm. Further, the volume shape factor is more preferably 0.4 to π / 6.

Further, on the surface of the coating layer B on the side not in contact with the base layer A, 50,000 to 100,000 particles are formed due to the inert fine particles A contained in the thermoplastic resin A. / Mm ²
It is preferable that the thermoplastic resin A contains the inert fine particles A in such a ratio that the projections are formed at a density of. The projection density is more preferably 0.75 to 60,000 / mm ² , and still more preferably 10,000 to 30,000 / mm ² .

When the average particle size is less than 30 nm or when the projection frequency is less than 50,000 / mm ^2, satisfactory running durability cannot be obtained. On the other hand, when the average particle size exceeds 400 nm, When the frequency of protrusions exceeds 100,000 / mm ² , electromagnetic conversion characteristics are inferior, and therefore it is not preferable.

The volume shape factor (f) of a particle is expressed by the following equation: f = V / R ³ [where f is the volume shape factor, and V is the volume of the particle (μ
m ³ ) and R are the average particle size (μm) of the particles. ]. A shape having a coefficient (f) of π / 6 is a sphere (true sphere). The shape having a coefficient (f) of 0.4 to π / 6 substantially includes a sphere (true sphere) and an elliptical sphere such as a rugby ball. It is difficult to obtain sufficient running durability with particles having a volume shape factor (f) of less than 0.1, for example, flaky particles.

In the laminated film of the present invention, a coating layer B containing a binder resin, inert fine particles and a surfactant is present on one surface of a base layer A. As the binder resin, for example, an aqueous polyester resin, an aqueous acrylic resin, an aqueous polyurethane resin, and the like are preferable, and an aqueous polyester resin is particularly preferable. As the aqueous polyester resin, for example, the acid component is isophthalic acid, phthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid It is composed of one or more polycarboxylic acids such as acid, succinic acid, 5-Na sulfoisophthalic acid, 2-K sulfoterephthalic acid, trimellitic acid, trimesic acid, monopotassium trimellitate, and p-hydroxybenzoic acid. ,
When the glycol component is, for example, ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, p-xylylene glycol, dimethylolpropanoic acid, or ethylene oxide addition of bisphenol A A polyester resin mainly composed of at least one polyvalent hydroxy compound such as a product is preferably used.
Further, a graft polymer or a block copolymer in which an acrylic polymer chain is bonded to a polyester chain, or two kinds of polymers have a specific physical configuration (IP
N, a core-shell) modified acrylic resin is also used. As the aqueous polyester resin, any type which can be dissolved, emulsified, or finely dispersed in water can be used freely, but a type which is emulsified or finely dispersed in water is preferable. These may have, for example, a sulfonic acid group, a carboxylic acid group, a polyether unit, or the like introduced into the molecule to impart hydrophilicity.

More preferably, the softening point (measured with a dried binder resin) of 50 ° C. measured according to JIS-K7206 in order to improve the corona resistance blocking.
Preferably, the Tg of the resin of the coating layer B is
Is too high, the surface of the layer B may be rough depending on the coating conditions and the like, and the electromagnetic conversion characteristics may be poor.

Therefore, when using a binder having a high Tg, it is necessary to devise coating conditions so as not to roughen the surface. The roughness in this case refers to a root-mean-square roughness measured at 10 μm by an AFM (scanning atomic force microscope), preferably 2.0 μm or less, more preferably 1.8 nm or less, and still more preferably. Is 1.5
nm or less.

Although the type of the inert fine particles is not particularly limited, those having a relatively low specific gravity which does not easily settle in the coating liquid are preferable. For example, heat-resistant polymers (for example, cross-linked silicone resin, cross-linked acrylic resin, cross-linked polystyrene, melamine / formaldehyde resin, aromatic polyamide resin,
Particles composed of a polyamideimide resin, a crosslinked polyester, a wholly aromatic polyester, etc.), silicon dioxide (silica), calcium carbonate and the like are preferred. Among these, particularly preferably, crosslinked silicone resin particles,
Silica and core-shell type organic particles (for example, core: crosslinked polystyrene, shell: polymethyl methacrylate particles, etc.). These inert fine particles preferably have an average particle size in the range of 10 to 50 nm. The average particle size is more preferably from 15 to 45 nm, even more preferably from 18 to 40 nm. These inert fine particles are contained at preferably 0.5 to 30% by weight, more preferably 2 to 20% by weight, based on the solid content of the coating layer B.

On the surface of the coating layer B which is not in contact with the base layer A, projections originating from inert fine particles contained in the coating layer B are preferably 1 to 40 / μm ² , more preferably Is 2 to 20 / m ² , particularly preferably 2.5 to 18
Particles / μm ² , especially 3 to 15 particles / μm ² . Also,
On the surface of the coating layer B which is not in contact with the base layer A, coarse projections having a height of 4 nm or more calculated from the surface roughness profile determined by a non-contact three-dimensional roughness meter, preferably at most 200 / mm ² or less, more preferably at most 1
It has a number of 00 / mm ² or less. Due to the presence of the above projection,
Excellent running durability is exhibited.

The surfactant (X) is used in an amount of 10 per solid content of the coating solution.
It is used in an amount of up to 50% by weight, preferably 12 to 40% by weight, particularly preferably 15 to 30% by weight. When the amount of the surfactant (X) is less than 10% by weight (based on the total solid content), it is not possible to suppress the generation of coarse projections that may cause dropout, while the amount of the surfactant (X) is 50% by weight (total). (Per solid), streaky coating defects due to foaming occur. It is preferable that the softening point (measured by drying a surfactant) measured in accordance with JIS-K7206 is 30 ° C. or more in order to improve the corona treatment blocking. However, in order to lower the surface tension of the coating liquid so as not to cause coating omission when applying the coating liquid, a surfactant Y other than those described above should be used in combination within a range not exceeding 10% by weight (per total solid content). Is also good. The surfactant X is preferably a nonionic surfactant, and particularly preferably a surfactant obtained by adding (poly) ethylene oxide to an alkyl alcohol, an alkylphenyl alcohol, a higher fatty acid, or the like.

As the surfactant, nonionic NS-230, NS-240, HS-220, manufactured by NOF Corporation as polyoxyethylene alkylphenyl ether compounds
HS-240, Sanyo Chemical Nonipol 200, Nonipol 400, Nonipol 500, Octapole 400,
Nonionic E-230, K-220, K-23 manufactured by NOF as polyoxyethylene alkyl ether compounds
0, Nonionic S-15.4 and S-40 manufactured by NOF can be exemplified as polyoxyethylene ester compounds of higher fatty acids.

Further, as the silicone contained in the coating layer B, as a chain component

[0032]

Embedded image

[Where R ₁ : CH ₃ , C ₆ H ₅ , HR ₂ : CH ₃ , C ₆ H ₅ , H or a functional group (for example, epoxy group, amino group, hydroxyl group) n: 100 to 7000] Which has an epoxy group, an amino group, a hydroxyl group, or another functional terminal group at the terminal. In the present invention, the silicone compound does not necessarily need to be a homopolymer, but may be a copolymer or a mixture of several types of homopolymers.

As the wax, for example, petroleum wax, vegetable wax, mineral wax, animal wax, low molecular weight polyolefin and the like can be used, and there is no particular limitation. Examples of the petroleum wax include paraffin wax, microcrystalline wax, and oxidized wax. Examples of the vegetable wax include candelilla wax, carnauba wax, wood wax, oligury wax, sugar cane wax, and rosin-modified wax.

The water-soluble or water-dispersible polysiloxane copolymerized polyester resin contained in the coating layer B is prepared by polymerizing siloxane or by adding a radical initiator to both ends of the polyester resin. Or by attaching a hydroxyl group to the side chain of the siloxane and reacting with a polyester having an isocyanate group or a carboxyl group at the end to form a comb polymer. Examples of the polyester resin component used for the polymerization include the same resins as those exemplified for the polyester resin used for the coating layer B. The siloxane is a compound similar to that shown in the above formula 1 as a chain component, and includes a compound having an epoxy group, an amino group, a hydroxyl group, or another functional terminal group at a terminal. In the present invention, the silicone compound does not necessarily need to be a homopolymer, but may be a copolymer or a mixture of several types of homopolymers. The ratio of the polyester resin component to the siloxane component is 98: 2 to 60:40, preferably 95: 5 to 80:20 by weight.

The content of silicone or wax in the coating layer B is 0.1 to 50% by weight, preferably 1 to 30% by weight. When the amount is less than 1% by weight, blocking occurs and the charge is increased. When the amount is more than 50% by weight, the adhesion of the magnetic layer is deteriorated, and the contact roll is stained during film running. The content of the polysiloxane copolymerized polyester resin in the coating layer B is 5 to 90% by weight, preferably 20 to 80% by weight. If the amount is less than 5% by weight, the effect is insufficient, causing the occurrence of blocking and increase in charging. If the amount exceeds 90% by weight, the adhesion of the magnetic layer is deteriorated, and the contact roll is stained during film running.

As described above, the laminated film of the present invention comprises:
On the surface of the coating layer B which is not in contact with the base layer A, coarse projections having a height of 4 nm or more calculated from the surface roughness profile determined by a non-contact three-dimensional roughness meter, preferably at most 200 / It has in mm ^2. The number of the coarse projections is 20
If it exceeds 0 / mm ² , it will itself be a cause of dropout, and if it is caused by poor dispersion of the inactive fine particles A, it will easily cause uneven wear of the head and deteriorate the electromagnetic conversion characteristics. Not preferred.

In order to enhance the dispersibility of the inert fine particles A in the thermoplastic resin layer A, for example, when a polyester is used as the thermoplastic resin A, the timing of introducing the polyester as a glycol slurry during the polymerization of the polyester is optimized. It is preferable to use a method, a method for optimizing the feeding rate of the glycol slurry, or to perform high-precision filtration before extruding a molten polymer from an extrusion die during film formation. In this high-precision filtration, it is preferable that the average opening of the filter, particularly the sintered metal fiber filter, be 50 times or more, more preferably 80 times or more the average particle size of the inert fine particles A. In particular, it is preferable to combine the optimization of the particle addition method with the optimization of the average aperture during high-precision filtration.

The laminated film of the present invention preferably has a thin film layer C on the other surface of the base layer A, that is, the surface that is not in contact with the coating layer B. The thin film layer C preferably contains inert fine particles. Further, the thin film layer C can be a coating layer or a thermoplastic resin layer formed by co-extrusion. When the thin film layer C is the coating layer C, the coating layer C can be composed of a binder resin and inert fine particles, and can further contain a surfactant. As the binder resin, the inert fine particles and the surfactant, the same ones as described for the coating layer B can be used. As the inert fine particles C, the average particle diameter is preferably 0.01 to 0.1 μm, more preferably 0.02 to 0.08 μm, and particularly preferably 0.02 to 0.08 μm.
One having a thickness of 0.06 μm is used. The amount of the inert fine particles is preferably 0.5 to 30% by weight, more preferably 1 to 20% by weight, and particularly preferably 2 to 10% by weight. In this case, the surfactants X and Y can be used alone or in combination. Therefore, the composition of the thin film layer C can be the same composition as the coating layer B. Further, as with the coating layer B, the coating layer C is coated with either silicone or wax.
It is preferable that the coating film mainly contains a water-soluble resin or a water-dispersible resin containing 50 to 90% by weight, or a coating film containing 5 to 90% by weight of a water-soluble or water-dispersible polysiloxane copolymerized polyester resin.

The thin film layer C is composed of a thermoplastic resin layer containing inert fine particles C, and may be formed by co-extrusion with the base layer A. At this time, between the thickness of the thin film layer C and the average particle size of the inert fine particles C, preferably, the following formula: 0.001 ≦ (dc) ³ × Cc × tc ≦ 100 [where dc (μm) is not The average particle size of the active fine particles, Cc (% by weight) is the content of the inert fine particles C,
Tc (nm) is the thickness of the thin film layer C. Is satisfied.

In the case where the thin film layer C is a coating layer, the above relationship is preferably 0.001 ≦ (dc) ³ × Cc × tc ≦ 0.1. 0.1 ≦ (dc) ³ × Cc × tc ≦ 100.

In this case, the thin film layer C formed by co-extrusion contains inert fine particles. The inert fine particles have the following average particle size and are contained in the following amounts. The average particle diameter d _C of the inert fine particles is 0.1 to 1 μm, and further 0.15 to 0.8 μm.
m, particularly preferably 0.2 to 0.7 μm. The content of the inert fine particles C having the average particle diameter d _C is as follows:
It is preferably 0.0001 to 1% by weight, more preferably 0.001 to 0.5% by weight, and particularly preferably 0.005 to 0.1% by weight, based on the thin film layer C.

Examples of the inert fine particles having an average particle diameter d _C include (1) flame-resistant polymer particles (eg, cross-linked silicone resin, cross-linked polystyrene, cross-linked acrylic resin, melamine-formaldehyde resin, aromatic polyamide resin, polyimide resin (2) metal oxides (eg, amylnium trioxide, titanium dioxide, silicon dioxide, magnesium oxide, zinc oxide, zirconium oxide, etc.), (3) metal carbonate ( For example, magnesium carbonate,
(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) And the like) 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, with crosslinked silicone resin particles, crosslinked polystyrene particles, alumina, titanium dioxide, silicon dioxide and calcium carbonate being particularly preferred. In addition, 2 inert particles
If it made of seed or more particles, the second average particle diameter smaller than the average particle diameter d _C of the inert fine particles C, as the third particle, for example colloidal silica, alpha, gamma, [delta], crystalline forms of θ such Fine particles, such as alumina, having the following can be preferably used. Fine particles having a small average particle size among the particle types exemplified as the inert particles having an average particle size d _C can also be used. The average particle size of the fine particles is 5 to 40.
0 nm, even 10-300 nm, especially 30-250 n
m and 50 nm more than the average particle diameter d _C.
As described above, it is preferable that the thickness is smaller by 100 nm or more, especially by 150 nm or more. The content of the second and third particles (fine particles) is 0.005 to 1% by weight, preferably 0.01 to 0.7% by weight, particularly 0.05 to 0.5% by weight with respect to the thin film layer C. % By weight.

The thermoplastic resin forming the thin film layer C may be the same as or different from the thermoplastic resin A forming the base layer A. Preferably they are the same. In particular, the base layer A and the thin film layer C are preferably made of polyethylene terephthalate or polyethylene-2,6-naphthalenedicarboxylate. As these polyesters, those having an intrinsic viscosity of about 0.4 to 0.9 measured at 35 ° C. as a solution in o-chlorophenol are preferred.

The laminated film of the present invention preferably exhibits an air bleeding index of 1 to 15 mm / hr due to the presence of the thin film layer C. The laminated film of the present invention comprises the above thin film layer C
Is present and the above-mentioned air bleeding index is exhibited, thereby improving the handling property and winding property of the film without impairing the electromagnetic conversion characteristics.

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 thin film layer C is 以下 or less of the total thickness of the laminated film, and
It is preferably at most / 3, particularly at most １ ／. The layer thickness of the coating layer B is 1 to 100 nm, and further 2 to 50 n.
m, particularly preferably 3 to 10 nm, more preferably 3 to 8 nm.

The laminated film of the present invention can be produced by a conventionally known method or a method accumulated in the art. Among them, the laminated structure of the base layer A and the thin film layer C is preferably manufactured by a co-extrusion method, and the lamination of the coating layer B is preferably performed by a coating method. For example, in the case of a biaxially oriented polyester film, polyester A in which the above-mentioned inert fine particles A are finely dispersed and contained in an extrusion die or before a die (generally, the former is called a multi-manifold system, and the latter is called a feed block system). And the fine particles of the inert fine particles C are further finely filtered, and then each of the polyesters C is laminated in a molten state to form a laminated structure having the above-mentioned preferred thickness ratio. After co-extrusion into a film at a temperature of (Tm + 70) ° C., the mixture is rapidly cooled and solidified with a cooling roll at 40 to 90 ° C. to obtain an unstretched laminated film. Thereafter, the unstretched laminated film is subjected to a uniaxial direction (longitudinal direction or transverse direction) at a temperature of (Tg-10) to (Tg + 70) ° C. (where Tg: glass transition temperature of the polyester) according to a conventional method. -8.0 times magnification, preferably 3.0-7.5 times
The film is stretched at twice the magnification, and then Tg in a direction perpendicular to the above direction.
(Tg + 70) ° C. at a temperature of 2.5 to 8.0 times,
Preferably, it is stretched at a magnification of 3.0 to 7.5 times. Further, if necessary, the film may be stretched again in the machine direction and / or the cross direction. That is, stretching in two, three, four, or multiple stages may be performed. The total stretching ratio is usually 9 times or more, preferably 12 to 35 times, more preferably 15 to 3 times, as the area stretching ratio.
It is 0 times. Subsequently, the biaxially oriented film is changed to (T
g + 70) to (Tm-10) ° C., for example, 180 to
Heat set crystallization at 250 ° C. provides excellent dimensional stability. The heat fixing time is preferably 1 to 60 seconds.

In the above method, a coating liquid containing the above-mentioned inert fine particles, a binder resin and a surfactant, preferably an aqueous coating liquid, is applied. The coating is preferably performed on the surface of the polyester layer A before the final stretching treatment, and after the coating, 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, and examples thereof include a roll coating method and a die coating method.

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. Then, other components such as other surfactants, stabilizers, dispersants, UV absorbers, and thickeners are added to the coating liquid (preferably an aqueous coating liquid) as long as the effects of the present invention are not impaired. can do. The above example is suitable when the thermoplastic resin A and the thermoplastic resin of the thin film layer C are both polyethylene-2,6-naphthalenedicarboxylate or polyethylene terephthalate, but only the base layer A or only the thin film layer C Is polyethylene-2,6-naphthalenedicarboxylate 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. 450kg / mm
² or more and 600 kg / mm ² or more, further 480 kg
/ Mm ² or more and 680 kg / mm ² or more, especially 550
kg / mm ² or more and 800 kg / mm ² or more, especially 5
It is preferred to be 50 kg / mm ² or more and 1000 kg / mm ² or more. The degree of crystallinity of the polyethylene terephthalate layer is 30 to 50%, and polyethylene-2,6-
The crystallinity of the naphthalenedicarboxylate layer is 28-3.
Preferably, it is 8%. If both fall below the lower limit,
When the heat shrinkage ratio is large, and when it exceeds the upper limit, the abrasion resistance of the film is deteriorated, and when the film slides on the roll or the guide pin surface, white powder is easily generated.

According to the present invention, a magnetic recording medium comprising the laminated film of the present invention as a base film, that is, a magnetic recording medium comprising the laminated film of the present invention and a magnetic layer present on the coating layer B of the laminated film Is provided as well.

An embodiment for producing a magnetic recording medium from the laminated film of the present invention is as follows.

The laminated film of the present invention is formed on the surface of the coating layer B by a method such as vacuum deposition, sputtering, or ion plating. A magnetic metal thin film layer is formed, and a protective layer of diamond-like carbon (DLC), etc.
By providing a fluorine-containing carboxylic acid-based lubricating layer in order and further providing a known back coat layer on the surface on the side of the thin film layer C if necessary, particularly in the short wavelength range, electromagnetic conversion such as S / N, C / N, etc. It is possible to obtain a vapor-deposited magnetic recording medium for high-density recording that has excellent characteristics and low dropout and error rate. This vapor-deposited magnetic 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 DDSIV tape medium.

The laminated film of the present invention further comprises a coating layer B
Iron or iron-like fine magnetic powder (metal powder) containing iron as a main component is uniformly dispersed in a binder such as polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, and the thickness of the magnetic layer is preferably 1 μm or less. Is applied so as to have a thickness of 0.1 to 1 μm, and if necessary, a back coat layer is provided on the surface on the side of the thin film layer C by a known method, so that output, especially in the short wavelength region, S / N, C / Excellent electromagnetic conversion characteristics such as 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 is dispersed and coated on the base 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 metal-coated magnetic recording medium is an 8 mm video for recording an analog signal, Hi8, β cam SP, W
It is extremely useful as a magnetic tape medium for VHS, 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 further comprises a coating layer B
On the surface of, needle-shaped fine magnetic powder such as iron oxide or chromium oxide,
Alternatively, plate-like fine magnetic powder such as barium ferrite is uniformly dispersed in a binder such as 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, if necessary, a back coat layer is provided on the surface on the side of the thin film layer C by a known method, so that output in a short wavelength region, S / S
Excellent electromagnetic conversion characteristics such as N, C / N, dropout,
A coating type magnetic recording medium for high density recording with a low error rate can be obtained. Also, if necessary, on the layer C,
A nonmagnetic layer containing fine titanium oxide particles or the like may be dispersed in the same organic binder as the magnetic layer and coated as a base layer of the magnetic powder-containing magnetic layer. 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.

[0058]

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

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

(2) Average particle size I of particles (average particle size: 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 the 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 Instruments I
nc. NICOMP MODEL 270 S
Expressed as the "equivalent sphere diameter" of the particles at the point of 50% by weight of the total particles as determined by UBMICRON PARTICLE SIZER.

(4) Thickness of Thermoplastic Resin Layers A and C 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 C are determined by measuring the thickness of the thinner layer by the method described below, and the thickness of the thicker layer is obtained by subtracting the thickness of the coating layer and the thickness of the thinner layer from the total thickness. That is, using a secondary ion mass spectrometer (SIMS), a metal element (M ⁺ ) and a polyester, which are caused by the highest concentration of particles in a film having a depth of 5000 nm from the surface layer excluding the coating layer, are used. The concentration ratio (M ⁺ / C ⁺ ) of the carbon element (C ⁺ ) is defined as the particle concentration, and analysis in the thickness direction is performed from the surface to a depth of 5000 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 is a case where the particle concentration once reaches a stable value 1 and then increases to a stable value 2 or a case where the particle concentration monotonously decreases. Based on this distribution curve, in the former case, the depth gives a particle concentration of (stable value 1 + stable value 2) / 2, and in the latter case, the depth at which the particle concentration becomes 1/2 of the stable value 1 The thickness (this depth is deeper than the depth giving a stable value of 1) was defined as the layer thickness of the layer.

The measurement conditions are as follows. Measurement device Secondary ion mass spectrometer (SIMS); 6300 manufactured by PERKINELMER Co., Ltd. Measurement conditions Primary ion species: O ₂ + Primary ion acceleration voltage: 12 KV Primary ion current: 200 nA Raster region: 400 μm Analysis region: Gate 30 % Measurement vacuum degree: 6.0 × 10 ⁻⁹ Torr E-GUNN: 0.5 KV-3.0 A

In the case where the particles most contained in the range of 5000 nm from the surface layer are organic polymer particles other than silicone resin, it is difficult to measure by SIMS. Therefore, FT-IR (Fourier transform infrared spectroscopy) is performed while etching from the surface. Method), and for some particles, the same thickness distribution curve as described above is measured by XPS (X-ray photoelectron spectroscopy) or the like to determine the layer thickness.

(5) The frequency of projections on the surface of the coating layer B due to the inert fine particles B (measured at 35,000 times) The frequency of projections on the film surface is measured by a scanning electron microscope. That is, 25 photographs of the surface of the coating layer B of the laminated film were taken at random at a magnification of 35,000, the frequency of surface protrusions was counted, and the average value was converted into the number of protrusions per 1 mm ^2. Inert fine particles B on the surface of the film layer B
Projection frequency.

(6) Protrusion frequency of inert fine particles A on the surface of coating film layer B (measured at 5000 times) The frequency of protrusions on the film surface is measured by a scanning electron microscope. That is, 25 photographs of the surface of the coating layer B of the laminated film were taken at random at a magnification of 5,000 times, the frequency of surface protrusions was counted, and the average value was converted into the number of protrusions per 1 mm ^2. The frequency of protrusion by the inert fine particles A on the surface of the film layer B is defined as the frequency.

(7) Center-surface average roughness Using a non-contact three-dimensional roughness tester (TOPO-3D) manufactured by WRa WYKO, measurement magnification is 40 times, and measurement area is 242 μm × 239 μm.
m (0.058 mm ² ) to obtain a surface roughness profile (original data). From the surface analysis using the built-in roughness meter software, WRa uses the value calculated by the following equation and output.

[0068]

(Equation 1)

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

(8) Number of Coarse Protrusions Using the profile (original data) of the surface roughness obtained in (7) above, the profile is divided into 15 continuous portions in the measurement direction (for example, j = 1 to 15). ) And an average value of heights in an area (15 × 15 divided area) formed by 15 successive divisions (for example, k = 1 to 15) in a direction orthogonal to the above (orthogonal direction) (j, k) =
The average height is (1, 1). Next, when one division position in the measurement direction or the orthogonal direction is moved by one (for example, j =
2-16, k = 1-15 or j = 1-15, k = 2-1
6) An average value of heights in an area of 15 × 15 divisions is determined, and is set as an average height of (j, k) = (2, 1) or (1, 2). Further, the division positions are moved one by one, for example, j = p
Ｐp + 14, k = q〜q + 14, the average height of the 15 × 15 divided areas is calculated, and (j, k) = (p,
The average height of q) is obtained, and the calculation of the average height is repeated up to 256 divisions in the measurement direction and 256 divisions in the orthogonal direction. The profile of the surface roughness constituted by these average heights corresponds to the undulating surface component of the film surface.

The profile of the film surface (reconstructed data) is reconstructed by subtracting the undulating surface component from the original data. The reconstructed data is analyzed with a built-in roughness meter software, and projections having a height of 4 nm or more are counted as coarse projections. This measurement is performed 10 times at different measurement points, and the average value is counted per 1 mm ^2. The value converted to is the number of coarse projections.

(9) 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. E = Δσ / Δε where E is Young's modulus (kg / mm ² ), Δσ is a 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.

(10) Air bleeding property Using a Beck smoothness tester manufactured by Toyo Seiki Co., Ltd., 40 films were first superimposed, and the remaining 39 films were removed, except for the one that came to the top of the sample table. Then, a hole having a diameter of 5 mmφ is made and set on the sample stage. At this time, the center of the hole is set at the center of the sample stage. 0.5 kg / c in this state
Apply a load of m ² and set the vacuum attainment to 550 mmHg. After reaching 550 mmHg, air flows between the films in order to return to normal pressure. At this time, the degree of vacuum (mmHg) falling every 30 seconds for one hour was measured, and the slope of the straight line when the degree of vacuum with respect to the measurement time (hr) was linearly approximated (= mmHg / h)
Let r) be the air leak index G.

(11) Number of Micro Protrusions The surface of the coating layer B on which aluminum was vapor-deposited to a thickness of 0.5 μm was coated with an optical microscope NIKON OPTIPH.
Observation was performed at 400 times magnification by differential interference spectroscopy using OT, and protrusions having a size of 2 μm or more in the longitudinal direction × 5 μm in the width direction were counted and converted into the number per 1 mm ² .

(12) Corona treatment Blocking force 100 mm in the longitudinal direction and 2 mm in the width direction of the roll film.
A rectangular sample of 00 mm is sampled and subjected to corona treatment on the base layer A side in an environment of a temperature of 25 ° C. ± 5 ° C. and a humidity of 50% ± 5%. The processing was performed under the following conditions using a CG-102 high frequency power supply manufactured by Kasuga Electric. Current: 4.5 A Distance between electrodes: 1.0 mm Processing time: Processed by passing between electrodes at a speed of 1.2 m / min. The processed film was immediately brought into contact with the surface opposite to the base layer A, and 100 kg / 60 ° C x 80% at a pressure of cm ²
After aging for 17 hours in the above environment, the peeling force per 100 mm width is determined by tension.

(13) AFM Roughness Using a J scanner of an atomic force microscope Nano Scope III AFM manufactured by Digital Instruments, the root mean square roughness calculated under the following conditions is measured under the following conditions. Probe: single bond silicon sensor Scanning mode: tapping mode Scanning range: 10 μm × 10 μm Number of pixels: 256 × 256 data points Scanning speed: 2.0 Hz Measurement environment: room temperature, in air The numerical values are the average of five measurements.

(14) Production of Magnetic Tape and Evaluation of Characteristics A 100% cobalt ferromagnetic thin film having a thickness of 0.2 μm was formed on the surface of the coating layer C of the biaxially oriented laminated film by a vacuum evaporation method. Layers (each layer thickness is about 0.1 μm)
A diamond-like carbon (DLC) film on its surface,
Further, a fluorine-containing carboxylic acid-based lubricating layer is sequentially provided, and a back coat layer is further provided on the surface of the thermoplastic resin C side by a known method. 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: 8 mm video tape recorder: EDV-6000 manufactured by Sony Corporation C / N measurement: Noise meter manufactured by Shibasoku Co., Ltd. C / N measurement A signal with a recording wavelength of 0.5 μm (frequency of about 7.4 MHz) was measured. After recording, 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 evaporation tape is defined as 0 dB. Criteria Criteria ◎: Compared with a commercially available 8 mm tape +5 dB or more ○: Compared with a commercially available 8 mm tape + 1 dB or more and less than +5 dB ×: Compared with a commercially available 8 mm tape + less than +1 dB 10 out
Measure for a minute and convert to the number per minute. Judge according to the following criteria. ：: Dropout 10 pieces / min or less ×: Dropout 11 pieces / min or more Running durability A 4.2 MHz video signal was recorded on the above-mentioned vapor-deposited tape, and the tape running speed 41 m / at 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. ：: output fluctuation after 200 repetitions is 0 dB to -0.3
dB ○: Output fluctuation after 200 repetitions is −0.3 dB to −
0.6 dB ×: the output fluctuation after 200 repetitions is −0.6 dB or less

[Examples 1 to 4] Dimethyl terephthalate and ethylene glycol were exchanged with magnesium acetate as a transesterification catalyst, titanium trimellitate as a polymerization catalyst, phosphorous acid as a stabilizer and a lubricant as shown in Table 1. Active fine particles were added and polymerized by a conventional method to obtain polyethylene terephthalate (PET) (resin A and resin C, respectively) for layer A and layer C having an intrinsic viscosity of 0.60.

The resin A and the resin C were dried at 170 ° C. for 3 hours, respectively, and then supplied to two extruders.
After melting at 0 to 300 ° C. and high-precision filtration with a steel wire filter having an average opening of 11 μm, a resin layer C is laminated on one side of the resin layer A using a multi-manifold type co-extrusion die, and quenched. An unstretched laminated film having a thickness of 89 μm was obtained.

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.
The film was stretched twice, rapidly cooled, and then an aqueous coating solution having a composition shown in Table 2 (total solid concentration: 1.0% by weight) was applied to the layer A side of the longitudinally stretched film by a kiss coating method, and then supplied to a stenter. Then, the film was stretched 4.2 times in the transverse direction at 110 ° C. The obtained biaxially stretched film was heat-set with hot air at 220 ° C. for 4 seconds to obtain a laminated biaxially oriented polyester film having a thickness of 6.4 μm. The thicknesses of the layers A and C were adjusted by the discharge amounts of the two extruders. Young's modulus of the film is machine direction 500 kg / mm ^2, it was transverse 700 kg / mm ^2.

Table 1 shows the surface characteristics of this laminated film and the characteristics of a ferromagnetic thin film-deposited magnetic tape using this film.
FIG.

Example 5 A laminated film was obtained in the same manner as in Example 1, except that polyethylene terephthalate having an intrinsic viscosity of 0.60 containing no inert fine particles was used as the thermoplastic resin for the layer A. Tables 1 to 7 show properties and the like of the obtained films.

Example 6 An unstretched film having a thickness of 89 μm was obtained in the same manner as in Example 1 from polyethylene terephthalate having the same intrinsic viscosity of 0.60 and containing no inert fine particles.

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.
The film was stretched twice, quenched, and then the water-based paint (B1) having the composition shown in Table 1 was applied to both sides of the longitudinally stretched film by a kiss coat method, and then supplied to a stenter. It was stretched twice. The obtained biaxially stretched film was heat-set with hot air at 220 ° C. for 4 seconds to obtain a laminated biaxially oriented polyester film having a thickness of 6.4 μm. The thicknesses of the layers A and C were adjusted by the discharge amounts of the two extruders. The Young's modulus of this film is 500 kg / mm
² , 700 kg / mm ² in the horizontal direction.

Tables 1 and 2 show the surface characteristics of the laminated film and the characteristics of the ferromagnetic thin film-deposited magnetic tape using this film.
FIG.

Example 7 The procedure of Example 6 was repeated except that the water-based paint (B1) and the water-based paint (B3) having the compositions shown in Table 1 were applied to the respective surfaces of the obtained longitudinally stretched film. 6 was carried out. The results are shown in Tables 1 to 7.

[Example 8] The result of the same procedure as in Example 7 except that the paint applied in Example 7 was an aqueous paint (B1) and an aqueous paint (B3 + R1) having the compositions shown in Tables 1 to 7. Are shown in Table 1.

Example 9 The base layer was made of polyethylene terephthalate having an intrinsic viscosity of 0.6 and containing no inert fine particles and having a thickness of 5.6 μm, and an average particle size of 0.6 μm.
0.1% by weight of silicone particles and an average particle size of 0.06 μm
This is the same as Example 7 except that the film is a laminated film composed of a 0.8 μm-thick layer made of polyethylene terephthalate containing 0.3% by weight of θ-alumina particles. However, the coating layer B was present on the layer containing no inert fine particles, and the thin film layer C was present on the layer containing the inert fine particles.
The results are shown in Tables 1 to 7.

Comparative Example 2 A laminated film was produced in the same manner as in Example 1 except that the opening of the steel wire filter used for high-precision filtration was changed to 4.8 μm after supplying the thermoplastic resin A to the extruder. I got Table 1 shows the characteristics of the laminated film and the ferromagnetic thin film-deposited tape using this film.
As is evident from Table 1, this film had a large number of surface roughness projections, so that the film had many dropouts when formed into a tape, and the running durability was lowered due to uneven wear of the head.

Example 10 The same procedure as in Example 1 was carried out except that the added inert fine particles and the layer thickness of the layers A and C were as shown in Table 1, and the composition of the coating layer B was as shown in Tables 1 to 7. The same laminated film was obtained. Table 1 shows the properties of the obtained film and the properties of a ferromagnetic thin film-deposited magnetic tape using this film.

Examples 11 to 13 Example 1 was repeated except that dimethyl 2,6-naphthalenedicarboxylate was used in the same molar amount instead of dimethyl terephthalate, and the fine particles shown in Tables 1 to 7 were used as inert fine particles. Layer A in the same manner as
Polyethylene-2,6-naphthalate for layer C (PE
N) (Resin A, Resin C) was obtained.

After drying each of the resin A and the resin C 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 the respective examples and comparative examples.

The unstretched film obtained in this way is preheated, and the film temperature is increased to 135 ° C. between low and high speed rolls.
In Example 11, 3.3 times in Example 11, 3.6 times in Example 12.
In Example 13, it was stretched to 4.0 times, quenched, and then an aqueous coating solution of the coating film B shown in Table 1 was applied in the same manner as in Example 1, and subsequently supplied to a stenter, and heated at 155 ° C. In Example 11, the film was stretched 6.4 times in Example 11, 5.6 times in Example 12, and 5.2 times in Example 13. The obtained biaxially stretched film was heat-set with hot air at 200 ° C. for 4 seconds to obtain a laminated film.

Comparative Example 1 Example 1 was repeated except that the added inert fine particles and the layer thickness of the layers A and C were as shown in Table 1, and the composition of the coating layer B was as shown in Tables 1 to 7. The same laminated film was obtained. Tables 1 to 7 show the characteristics of the obtained film and the characteristics of a ferromagnetic thin film-deposited magnetic tape using this film.

Examples 14 to 17 and Comparative Examples 3 to 6 Laminated films were obtained in the same manner as in Example 1 except that the composition of the coating layer B was as shown in Tables 1 to 7. Tables 1 to 7 show the characteristics of the obtained film and the characteristics of a ferromagnetic thin film-deposited magnetic tape using this film.

As is clear from Tables 1 to 7, the laminated films of the examples show excellent electromagnetic characteristics, not only very few fine projections that cause dropout, but also anti-corona treatment blocking. Power is good. Furthermore, the laminated film of the example has an appropriate amount of inert fine particles added to the layer A corresponding to the magnetic layer surface side and a small number of coarse particles, so that the dropout due to these is small and the running durability is excellent. ing. On the other hand, the film of the comparative example cannot satisfy these characteristics at the same time.

[0098]

[Table 1]

[0099]

[Table 2]

[0100]

[Table 3]

[0101]

[Table 4]

[0102]

[Table 5]

[0103]

[Table 6]

[0104]

[Table 7]

[0105]

According to the present invention, a magnetic recording medium having good blocking resistance against corona treatment, excellent running durability and electromagnetic conversion characteristics even when used as a vapor-deposited metal thin film type magnetic recording medium, and extremely low dropout. A laminated film capable of producing a medium can be provided.

Claims (18)

[Claims] 1. A laminated film comprising a base layer A made of a thermoplastic resin A and a coating layer B present on one surface of the base layer A, wherein the coating layer B is composed of a binder resin and inert fine particles. The coating film is mainly composed of a water-soluble resin or a water-dispersible resin containing 1 to 50% by weight of any one of silicone, wax and silicone, and has a peeling force of 15 g / 10 cm or less for corona treatment blocking. The laminated film characterized by the above. 2. The method according to claim 1, wherein the coating layer B is a binder resin.
5 to 90% by weight of an inert fine particle surfactant and a water-soluble or water-dispersible polysiloxane copolymerized polyester resin
It has a coating force of 1 with corona treatment blocking.
A laminated film having a weight of 5 g / 10 cm or less. 3. The laminated film according to claim 1, wherein the thermoplastic resin A forming the base layer A contains substantially no inert fine particles. 4. The thermoplastic resin A forming the base layer A has an average particle size of 30 to 400 nm and a volume shape factor of 0.1 to π /
The laminated film according to claim 1, comprising the inert fine particle A of No. 6. 5. A density of 50,000 to 100,000 particles / mm ² on the surface of the coating layer B on the side not contacting the base layer A due to the inert fine particles A due to the inert fine particles A. 3. The laminated film according to claim 1, wherein the thermoplastic resin A is contained in the thermoplastic resin A in such a ratio as to produce protrusions. 6. The coating layer B, wherein the surface of the coating layer B which is not in contact with the base layer A has 1 to 40 protrusions / μm ^{2 due} to inert fine particles contained in the coating layer B. And the laminated film according to 2. 7. The inert fine particles in the coating layer B have an average particle size in the range of 10 to 50 nm, and the content is 0.5 to 30% by weight based on the solid content of the coating layer B. The laminated film according to claim 1, wherein the laminated film is formed. 8. The method according to claim 1, wherein the coating layer B has a maximum height of 4 nm or more on the surface that is not in contact with the base layer A, calculated from a surface roughness profile obtained by a non-contact three-dimensional roughness meter. The laminated film according to claim 1, wherein the number of the laminated films is 200 / mm ² or less. 9. The laminated film according to claim 1, wherein the surfactant is a nonionic surfactant. 10. The laminated film according to claim 1, wherein the binder resin of the coating layer B is an aqueous polyester resin. 11. The thin film layer C is further present on a surface of the base layer A which is not in contact with the coating layer B.
3. The laminated film according to item 1. 12. The thin film layer C is a coating layer comprising a binder resin, inert fine particles and a surfactant.
3. The laminated film according to item 1. 13. The laminated film according to claim 11, wherein the thin film layer C has the same composition as the coating layer B. 14. The laminated film according to claim 11, wherein the thin film layer C comprises a thermoplastic resin layer containing inert fine particles C and is formed by co-extrusion with the base layer A. 15. The thin film layer C has the following formula: 0.001 ≦ (dc) ³ × Cc × tc ≦ 100 [where dc (μm) is the average particle size of the inert fine particles C, and Cc (% by weight) Is the content of the inert fine particles C, and tc (nm) is the thickness of the thin film layer C. The laminated film according to claim 14, which satisfies the following. 16. The laminated film has an air bleeding index of 1 to 15.
The laminated film according to claim 11 or 14, which exhibits mmHg / hr. 17. A magnetic recording medium comprising the laminated film according to claim 1 and a magnetic layer present on the coating layer B of the laminated film. 18. The magnetic recording medium according to claim 18, wherein the magnetic recording medium is for Hi8 for recording an analog signal, a digital video cassette recorder for recording a digital signal or 8 mm data, and DDSIV.