JP3258259B2 - Laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film, and more particularly, to a laminated film which is excellent in running durability and electromagnetic conversion characteristics and which is useful as a base film of a magnetic recording medium with 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 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. , The surface state of the nonmagnetic support is directly expressed 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.

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 The slip property deteriorates, a blocking phenomenon occurs, and the shape when wound on a roll (roll formation) deteriorates, resulting in a decrease in product yield and a rise in product manufacturing cost. Therefore,
From the viewpoint of manufacturing cost, it is desirable that the surface of the nonmagnetic support (base film) be as rough as possible.

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.

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.

In Japanese Patent Application Laid-Open No. 5-194772, a primer layer for a magnetic layer, which is a continuous thin film, is coated on one surface of a polyester film, and the surface of the continuous thin film of the primer layer is (A). And (B) small protrusions having a height of 13 nm or less and having particles having an average particle diameter of less than 0.06 μm as nuclei.
30 n height with particles having an average particle size of 0.06 μm or more as nuclei
m and small projections made of only the resin forming the primer layer (C), and the number of these projections is represented by the following formula: A _N ≧ 1.0 × 10 ⁶ (pieces / mm ² ) B _N ≧ 1 0.05 × 10 ⁴ (pieces / mm ² ) A _N ≦ −3.4 × 10 ² · B _N + 13.6 × 10 ⁶ (pieces / mm ² ) C _N ≦ 4.0 × 10 ⁶ (pieces / mm ²⁾ (However, A _N is the number of small projections (pieces / mm ² ), B _N is the number of large projections (pieces / mm ² ), and C _N is the number of minute projections (pieces / m ² ).
m ² ). ) Satisfied, and micro surface roughness Ra ^S only by a continuous thin film of the resin for forming the primer layer is not more than 1.10 nm, and a surface roughness Ra of the continuous film is 1 to 10 nm, the magnetic recording A polyester film for media is disclosed.

In Japanese Patent Application Laid-Open No. 5-298670, a primer layer for a magnetic layer, which is a continuous thin film, is coated on one surface of a polyester film. A) Average particle size 0.06 μm
Only small protrusions having a height of 13 nm or less, whose cores are smaller than particles, and (B) large protrusions having a height of 30 nm or less, whose cores are particles having an average particle size of 0.06 μm or more, and (C) a resin forming a primer layer only. And the number of these protrusions is expressed by the following formula: A _N ≧ 1.0 × 10 ⁶ (pieces / mm ² ) B _N ≧ 1.05 × 10 ⁴ ( Pcs / mm ² ) A _N ≦ −3.4 × 10 ² · B _N + 13.6 × 10 ⁶ (pcs / mm ² ) 1.0 × 10 (pcs / mm ² ) ≦ C _N <1.0 × 10
⁴ (pieces / mm ² ) (where, A _N is the number of small projections (pieces / mm ² ), B _N is the number of large projections (pieces / mm ² ), and C _N is the number of micro projections (pieces / m ² ).
m ² ). ) Satisfied, micro surface roughness Ra ^S only by a continuous thin resin forming the primer layer is 1.
10 nm or less, and the surface roughness R of the continuous thin film
a is 1 to 10 nm, and the continuous thin film can suppress the precipitation rate of polyester oligomer microcrystals on the film surface to 0.8% or less when the film is continuously heated in air at 160 ° C. for 5 minutes. A polyester film for a recording medium 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.

In the above method, particles are added to the base film on the side of the magnetic layer in order to improve running durability. However, since the dispersibility of the particles is poor, there are many coarse projections, and this is the cause of dropout. And the output is reduced due to uneven wear of the magnetic head.

[0014]

SUMMARY OF THE INVENTION 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 provide a magnetic recording medium which has a significantly reduced dropout due to coarse projections resulting from a coating layer forming coating solution, excellent running durability, excellent electromagnetic conversion characteristics, and extremely low dropout. It is to provide a laminated film for giving the following. Still other objects and advantages of the present invention will become apparent from the following description.

[0015]

According to the present invention, the above objects and advantages of the present invention comprise a base layer A comprising a thermoplastic resin A and a coating layer B present on one surface of the base layer A. A laminated film, wherein the base layer A is formed
Thermoplastic resin A has an average particle size of 40 to 400 nm and a volume
The coating layer B contains a binder resin, inert fine particles, and a surfactant . The coating layer B contains inert particles A having a shape factor of 0.1 to π / 6. 0.1 to 15% by weight of a surfactant X having an HLB value of 10 to 14 and an HLB value of 16 to 18.
HLB (X) + P (X) where HLB (X) and P (X) are each represented by the following formula: Average HLB = HLB (X) × P (X) + HLB (Y) × P (Y) HLB value and weight fraction of surfactant X (weight fraction of surfactant X relative to total weight of surfactants X and Y) and HLB (Y) and P (Y) are surfactant Y
Are the HLB value and the weight fraction.

It is achieved by a laminated film characterized in that it is contained in such a proportion that the average HLB value defined in the above becomes 15 to 18.

The laminated film of the present invention is, as described above,
It comprises a base layer A made of a thermoplastic resin A and a coating layer B present on one surface of the base layer A.

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 in the case of other polyesters than polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate can be considered in the same manner as described above.

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

The thermoplastic resin A forming the base layer A is
Containing inert particles.

[0025] The inert particulate has an average particle diameter of from 40 to 40
Inert fine particles A having a diameter of 0 nm and a volume shape factor of 0.1 to π / 6. The average particle size is good Mashiku 50
It is 200 nm, particularly preferably 60 to 120 nm.
The volume shape factor, good Mashiku is 0.4~π / 6.

Further, on the surface of the coating film 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 diameter is less than 40 nm or when the projection frequency is less than 50,000 / mm ^2, satisfactory running durability cannot be obtained, while when the average particle diameter 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 the 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 (μm
³ ), R is 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 the 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, succinic acid, 5-N
a Sulfoisophthalic acid, 2-K sulfoterephthalic acid, trimellitic acid, trimesic acid, trimellitic acid monopotassium salt, and at least one polycarboxylic acid such as p-hydroxybenzoic acid, wherein the glycol component is, for example, ethylene glycol Polyhydric hydroxy such as diethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, p-xylylene glycol, dimethylolpropanoic acid, and ethylene oxide adduct of bisphenol A A polyester resin mainly composed of at least one compound is preferably used. Also, a graft polymer or a block copolymer in which an acrylic polymer chain is bonded to a polyester chain, or an acrylic-modified polyester resin in which two types of polymers form a specific physical configuration (IPN, core shell) in a micro molecule are similarly used. Can be 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.

The type of the inert fine particles is not particularly limited, but is preferably one having a relatively low specific gravity which does not easily settle in the coating liquid. 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 have an average particle size of 10 to 10.
Preferably it is in the range of 50 nm. The average particle size is more preferably from 15 to 45 nm, even more preferably 18 to 45 nm.
４０40 nm.

These inert fine particles are contained in an amount of 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 .

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 are preferably used. It has a maximum of 200 / mm ² or less, more preferably a maximum of 100 / mm ² or less.

Due to the presence of the projections, excellent running durability is exhibited. As the surfactant, 2 having different HLB values are used.
A combination of different surfactants is used. The HLB value of one surfactant X is 10 to 14, and the HLB value of the other surfactant Y is 16 to 18.5.

The HLB value of the surfactant X is preferably 1
0.5-13.5, more preferably 11.0-13.0
It is.

The HLB value of the surfactant Y is preferably 16.5 to 18.3, more preferably 17.0 to 1.
8.0.

Further, the surfactant X is used in an amount of 0.1 to 15% by weight, preferably 0.65 to 10% by weight, particularly preferably 0.85 to 5% by weight, based on the solid content of the coating solution. . The surfactant Y is used in an amount of 10 to 4 per solid content of the coating liquid.
It is used in an amount of 0% by weight, preferably 12-36% by weight, particularly preferably 15-30% by weight.

In the above weight ratio, the surfactant X and the surfactant Y are represented by the following formula: average HLB value = HLB (X) × P (X) + HLB (Y)
× P (Y) where HLB (X): HLB value of surfactant X P (X): weight fraction of surfactant X (surfactant based on total weight of surfactant X and surfactant Y) HLB (Y): HLB value of surfactant Y P (Y): Weight fraction of surfactant Y (Surfactant Y to total weight of surfactant X and surfactant Y) (Weight fraction) is used in such a ratio that the average HLB value defined by the following formula is 15 to 18. The average HLB value is preferably between 15.5 and 17.
5, more preferably 16 to 17.5.

If the HLB value of the surfactant X is less than 10 or the amount thereof exceeds 15% by weight (based on the total solid content), foaming tends to occur when the coating solution is applied, and streak-like coating defects are reduced. I can do it. On the other hand, when the HLB value exceeds 14, or the amount used is less than 0.5% by weight (per total solid content),
Since the effect of lowering the surface tension of the coating liquid is reduced, a coating omission occurs when the coating liquid is applied.

If the HLB value of the surfactant Y is less than 16 or the amount is less than 10% by weight (based on the total solid content), it is impossible to suppress the formation of coarse projections which may cause a dropout. On the other hand, the HLB value If it exceeds 18.5, application omission occurs, and the amount used is 40% by weight (per total solids).
If it exceeds 300, streaky coating defects due to foaming will occur.

Further, the average HLB value of the surfactant is 15
If it is less than 18, coarse projections that cause dropout occur, while if it exceeds 18, coating omission occurs.

Further, when only one of the surfactants X and Y is used, the generation of coarse projections derived from agglomerated particles, which is a cause of dropout, can be suppressed, and the coating drop or foam due to repelling can be prevented. It is not possible to solve problems in coating such as streaks.

The surfactant 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 X, nonionic NS-208.5 (HLB12.6) manufactured by NOF Corporation as a polyoxyethylene alkylphenyl ether compound, NS
-206 (HLB10.9), HS-208 (HLB1
2.6), NS-210 (HLB13.6), octapole 60 (HLB11.3), octapole 80 (HLB12.4), octapole 95 (HLB) manufactured by Sanyo Kasei
13.3), Octapole 100 (HLB 13.6),
Dodecapol 90 (HLB12.0), Dodecapol 1
20 (HLB13.4), Nonionic P-21 manufactured by NOF Corporation as a polyoxyethylene alkyl ether compound
0 (HLB12.9), Sanyo Kasei nonipol software SS-50 (HLB10.5), SS-70 (HLB1
2.8), SS-90 (HLB 13.2), DO-70
(HLB12.3), DO-90 (HLB13.4),
Nonionic L-4 (HLB13.1) manufactured by NOF Corporation as polyoxyethylene ester-based compound of higher fatty acid, S
-4 (HLB 11.6), S-6 (HLB 13.6) and the like. As the surfactant Y, a nonionic NS-230 (HLB manufactured by NOF Corporation) as a polyoxyethylene alkyl phenyl ether compound is used.
17.2), NS-240 (HLB17.8), HS-
220 (HLB16.2), HS-240 (HLB1
7.9), Sanyo Chemical Nonipol 200 (HLB1
6.0), Nonipol 400 (HLB 17.8), Nonipol 500 (HLB 18.2), Octapole 400
(HLB17.9), Nonion E-230 manufactured by NOF Corporation as a polyoxyethylene alkyl ether compound.
(HLB16.6), K-220 (HLB16.2),
K-230 (HLB17.3), nonionic S-15.4 (HLB16.7), S-40 (HLB) manufactured by NOF as polyoxyethylene ester compounds of higher fatty acids
18.2) and the like.

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.

When the number of the coarse projections exceeds 200 / mm ² , the head itself becomes a cause of dropout, and when the number of coarse projections is caused by poor dispersion of the inert fine particles A, the head tends to be unevenly worn. It is not preferable because the characteristics are also deteriorated.

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 charging the slurry 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 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 0.0 to 0.1 μm.
2 to 0.08 μm, particularly preferably 0.02 to 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.
%, 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.

The thin film layer C is composed of a thermoplastic resin layer containing inert fine particles C, and may be formed by coextrusion 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 inert The average particle diameter of the 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. To be satisfied.

When the thin film layer C is a coating film layer, the above relationship is preferably 0.001 ≦ (dc) ³ × Cc × tc ≦ 0.1. Is 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 inert fine particles have an average particle diameter d _C of 0.1 to 1
μm, more preferably 0.15 to 0.8 μm, especially 0.2 to 0.5 μm.
It is preferably 7 μm. Further, the content of the inert fine particles C having the average particle diameter d _C is
0.0001 to 1% by weight, more preferably 0.001 to 0.5
% By weight, particularly preferably 0.005 to 0.1% by weight.

Examples of the inert fine particles having an average particle diameter d _C include (1) flame-resistant polymer particles (for example, 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, particularly, 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 Kaolin is preferred, with crosslinked silicone resin particles, crosslinked polystyrene particles, alumina, titanium dioxide, silicon dioxide and calcium carbonate being particularly preferred.

Further, when the inert fine particles are composed of two or more kinds of particles, as the second and third particles having an average particle diameter smaller than the average particle diameter d _C of the inert fine particles C, for example, colloidal silica, α , Γ, δ, θ and the like 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 400 n.
m, more preferably in the range of 10 to 300 nm, especially 30 to 250 nm, and preferably smaller than the average particle diameter d _C by 50 nm or more, more preferably 100 nm or more, especially 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. weight%
It is preferable that

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.

In the laminated film of the present invention, the handling property and the winding property of the film can be improved without impairing the electromagnetic conversion properties by the presence of the thin film layer C and the above-mentioned air bleeding index.

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, the above-mentioned inert fine particles A are finely dispersed and contained in the extrusion die or before the die (generally, the former is called a multi-manifold system, and the latter is called a feed block system). The polyester A and the inert fine particles C are finely dispersed and the polyester C containing the fine particles is further subjected to high-precision filtration, and then laminated and composited in a molten state to form a laminated structure having the above-mentioned preferred thickness ratio. Tm ° C ~ (Tm + 70)
After co-extruding into a film at a temperature of ℃, it is quenched and solidified by a cooling roll at 40 to 90 ℃ to obtain an unstretched laminated film. Thereafter, the unstretched laminated film is uniaxially (longitudinal or transverse) (Tg-10) to (Tg + 7) according to a conventional method.
0) At a temperature of 0 ° C. (where Tg: glass transition temperature of the polyester), a magnification of 2.5 to 8.0 times, preferably 3.
The film is stretched at a magnification of 0 to 7.5 times, and then at a temperature perpendicular to the above direction at a temperature of Tg to (Tg + 70) ° C at a magnification of 2.5 to 8.0 times, preferably 3.0 to 7.5 times. It is stretched at a magnification of. 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 stretch ratio is usually 9 times or more, preferably 12 to 35 times, more preferably 15 to 30 times as the area stretch ratio. Subsequently, the biaxially oriented film is heat-set and crystallized at a temperature of (Tg + 70) to (Tm−10) ° C., for example, 180 to 250 ° C., thereby giving excellent dimensional stability. The heat setting time is 1 to
60 seconds is preferred.

In the above method, a coating solution containing the above-mentioned inert fine particles, the binder resin, the surfactant X and the surfactant Y, preferably an aqueous coating solution, 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 concentration 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, particularly 0.1% 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 both the thermoplastic resin A and the thermoplastic resin of the thin film layer C are polyethylene-2,6-naphthalenedicarboxylate or polyethylene terephthalate. The same applies to the case where only the layer C is made of 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 coloring agent, 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 longitudinal and transverse directions, respectively. 450kg / mm
² or more and 600 kg / mm ² or more, furthermore 480k
g / mm ² or more and 680 kg / mm ² or more, especially 5
50 kg / mm ² or more and 800 kg / mm ² or more,
Inter alia 550kg / mm ² or more and 1000kg / mm
^It is preferably at least ² . The crystallinity of the polyethylene terephthalate layer is 30 to 50%,
The crystallinity of the 2,6-naphthalenedicarboxylate layer is desirably 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.

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.

Embodiments for producing a magnetic recording medium from the laminated film of the present invention are as follows. The laminated film of the present invention is a ferromagnetic metal thin film composed of iron, cobalt, chromium, or an alloy or oxide containing these as a main component on the surface of the coating layer B by a method such as vacuum deposition, sputtering, or ion plating. A protective layer of diamond-like carbon (DLC) or the like and a fluorinated carboxylic acid-based lubricating layer are sequentially provided on the surface thereof, if necessary, and if necessary, a surface on the thin film layer C side. By providing a well-known back coat layer, it is possible to obtain a vapor-deposited magnetic recording medium for high-density recording, which is particularly excellent in output in the short wavelength region, electromagnetic conversion characteristics such as S / N and C / N, and has low dropout and error rate. You can do it. This vapor-deposited magnetic recording medium is a digital video cassette recorder (DV8) for recording Hi8 for recording analog signals,
C), data 8 mm, extremely useful as a tape medium for DDSIV.

The laminated film of the present invention also 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.

[0077]

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 It is 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.
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) HLB value The HLB value is obtained from the following equation.

[0081]

(Equation 1)

Here, M: molecular weight of the surfactant Mn: molecular weight of the hydrophilic group portion See “Oil Chemistry” 13, 220 (1964).

(5) 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 area: 400 μm □ Analysis area: Gate 30% Measurement vacuum degree: 6.0 × 10 ⁻⁹ Torr E-GUNN: 0.5 KV-3.0 A In the case where the particles contained most 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 described above is measured by FT-IR (Fourier transform infrared spectroscopy) or XPS (X-ray photoelectron spectroscopy) depending on the particles while etching from the surface, and the layer thickness is measured. Ask for.

(6) Protrusion frequency of inert fine particles B on the surface of coating layer B (measured at 35,000 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 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.

(7) 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.

(8) Center Surface Average Roughness Using a non-contact three-dimensional roughness meter (TOPO-3D) manufactured by WRa WYKO, a measurement magnification of 40 times, and a measurement area of 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.

[0088]

(Equation 2)

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.

(9) Number of Coarse Protrusions Using the profile of the surface roughness (original data) obtained in (8) 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.

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

(11) Air bleeding property Using a Beck smoothness tester manufactured by Toyo Seiki Co., Ltd., forty sheets of film were first superimposed, and the remaining 39 sheets were removed, except for the one at 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.

(12) 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 .

(13) Omission of coating, streaks The coating layer B was immersed in a dyeing solution having the following composition (temperature: 50 ° C.) for 10 minutes, washed with water, visually observed, and dyed into an oval to spherical shape. An area where there is no area is determined to be missing, an area having a streak in the longitudinal direction is determined as an applied stripe, and an area that does not exist is determined as ○, and an existing area is determined as x. Staining solution composition: methylene blue 10 parts by weight benzyl alcohol 30 parts by weight Kayakaran red 2 parts by weight Rhodamine B 2 parts by weight Deionized water 1956 parts by weight

(14) Production of Magnetic Tape and Evaluation of Characteristics A 100% cobalt ferromagnetic thin film was formed on the surface of the coating layer C of the biaxially oriented laminated film by a vacuum evaporation method so as to have a thickness of 0.2 μm. 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: 8mm video tape recorder: EDV manufactured by Sony Corporation
-6000 C / N measurement: Noise meter manufactured by Shibasoku Co., Ltd.

C / N Measurement A signal having a recording wavelength of 0.5 μm (frequency of about 7.4 MHz) was recorded, and the ratio of the value of the reproduced signal between 6.4 MHz and 7.4 MHz was defined as the C / N of the tape. The C / N of the 8 mm video evaporation tape was set to 0 dB, and the evaluation was made based on the following criteria. Judgment Criteria: +5 dB or more compared to a commercially available 8 mm tape ：: +1 dB or more and less than +5 dB compared to a commercially available 8 mm tape ×: Less than +1 dB compared to a commercially available 8 mm tape

Dropout Using a dropout counter manufactured by Shibasoku Co., Ltd., a dropout of 3 μsec / 10 dB or more was measured for 10 minutes.
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 video signal of 4.2 MHz was recorded on the above-mentioned vapor-deposited tape, and the tape running speed was 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

Example 1 Dimethyl terephthalate and ethylene glycol, magnesium acetate as a transesterification catalyst, titanium trimellitate as a polymerization catalyst, phosphorous acid as a stabilizer, and inert fine particles shown in Table 1 as a lubricant Was 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 136 μm was obtained.

The obtained unstretched film is preheated, and is further moved 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 9.8 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, lateral 700 kg / mm ²
Met.

Table 3 shows the surface characteristics of this laminated film and the characteristics of a ferromagnetic thin film-deposited magnetic tape using this film.

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

Comparative Example 6 A laminated film was prepared 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 3 shows the characteristics of the laminated film and the ferromagnetic thin film-deposited tape using this film.
As is evident from Table 3, this film has a large number of surface rough projections, so that the film has many dropouts when used as a tape, and the running durability is lowered due to uneven wear of the head.

[Examples 2 to 3 and Comparative Examples 1 to 3] The added inert fine particles and the layer thickness of the layers A and C are as shown in Table 1, and the composition of the coating layer B is as shown in Table 2. Other than that, a laminated film similar to that of Example 1 was obtained. Table 3 shows the properties of the obtained film and the properties of a ferromagnetic thin film-deposited magnetic tape using this film.

Examples 4 to 6 and Comparative Examples 4 and 5 Instead of dimethyl terephthalate, the same molar amount of dimethyl 2,6-naphthalenedicarboxylate was used, and the fine particles shown in Table 1 were used as inert fine particles. In the same manner as in Example 1, polyethylene-2,6-naphthalate (PEN) (resin A, resin C) for layers A and 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 135
At 3.3 ° C. in Example 8, 3.3 times, Example 9, Comparative Examples 4 to 6
In Example 10, the film was stretched to 3.6 times, and in Example 10, it was stretched to 4.0 times, quenched, and then an aqueous coating solution of the coating film B shown in Table 2 was applied in the same manner as in Example 1, and subsequently supplied to a stenter. At 155 [deg.] C. in the lateral direction, Example 8 was 6.4 times, Example 9, Comparative Example 5
In Example 7, the film was stretched 5.6 times, and in Example 10, the film was stretched 5.2 times.
The obtained biaxially stretched film was heat-set with hot air at 200 ° C. for 4 seconds to obtain a laminated film.

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

[0116]

[Table 1]

[0117]

[Table 2]

[0118]

[Table 3]

As is evident from Table 3, the laminated films of the examples show excellent electromagnetic characteristics and not only very few fine projections causing dropout, but also defects such as coating omissions and coating streaks. Absent. 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
These characteristics cannot be satisfied simultaneously.

[0120]

According to the present invention, it is possible to significantly reduce the coarse projections which cause a drop-out due to the coating liquid for forming a coating film layer and to control the dispersibility of the particles in the base film. Even when used as a vapor-deposited metal thin-film type magnetic recording medium, it is possible to provide a laminated film which is excellent in running durability and electromagnetic conversion characteristics and can produce a magnetic recording medium with extremely small dropout.

────────────────────────────────────────────────── (5) References JP-A-10-6449 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 C08J 7 / 04 EPAT (QUESTEL) WPI (DIALOG)

Claims (20)

(57) [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.
Plastic resin A has an average particle size of 40 to 400 nm and volume shape factor
Containing 0.1 to π / 6 of inert fine particles A,
Comprises a binder resin, inert fine particles and a surfactant, and as the surfactant, a surfactant X having an HLB value of 10 to 14 based on the solid content of the coating layer B.
0.1 to 15% by weight and 10 to 40% by weight of a surfactant Y having an HLB value of 16 to 18.5 are represented by the following formula: average HLB = HLB (X) × P (X) + HLB (Y) × P (Y Where HLB (X) and P (X) are the HLB value and the weight fraction of surfactant X (weight fraction of surfactant X relative to the total weight of surfactants X and Y), respectively, and HLB (Y) and P (Y) are each a surfactant Y
Are the HLB value and the weight fraction. Mean H defined by
A laminated film characterized by containing an LB value of 15-18. ^2. A density of 50,000 to 100,000 particles / mm ² on the surface of the coating layer B on the side that does not contact the base layer A due to the inert fine particles A due to the inert fine particles A. The laminated film according to claim 1, which is contained in the thermoplastic resin A in such a ratio as to generate protrusions. 3. The method according to claim 1, 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 the inert fine particles contained in the coating layer B. 3. The laminated film according to item 1. 4. 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 thereof is 0.5 to 30% by weight based on the solid content of the coating layer B. The laminated film according to claim 1, which is produced. 5. A method according to claim 1, wherein the coating layer has a maximum size of 4 nm or more on the surface not in contact with the base layer, 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 is 200 or less / mm ² or less. 6. The surfactant X having an HLB value of 10.5 to 1
2. The laminated film according to claim 1, wherein the thickness is 3.5. 7. The laminated film according to claim 1, wherein the surfactant X is contained at 0.65 to 10% by weight based on the solid content of the coating layer B. 8. The surfactant Y having an HLB value of 16.5 to 1
The laminated film according to claim 1, wherein the thickness is 8.3. 9. The laminated film according to claim 1, wherein the surfactant Y is contained in an amount of 12 to 36% by weight based on the solid content of the coating layer B. 10. The laminated film according to claim 1, comprising surfactants X and Y in a ratio such that the average HLB value is 15.5 to 17.5. 11. The laminated film according to claim 1, wherein the surfactants X and Y are nonionic surfactants. 12. The laminated film according to claim 1, wherein the binder resin of the coating layer B is an aqueous polyester resin. 13. The laminated film according to claim 1, further comprising a thin film layer C on a surface of the base layer A which is not in contact with the coating layer B. 14. The method of claim 1 3 thin film layer C is a coating layer made of a binder resin, inert particles and a surfactant
3. The laminated film according to item 1. 15. The laminated film according to claims 1 to 3, thin layer C is composed of the same composition as the coating film layer B. The laminated film according to claims 1 to 3, 16. The thin film layer C is formed by coextrusion with it and base layer A of a thermoplastic resin layer containing inert fine particles C. 17. 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 Content of inert fine particles C,
Tc (nm) is the thickness of the thin film layer C. The laminated film according to claim 16 , which satisfies the following. 18. The laminated film has an air bleeding index of 1 to 15.
The laminated film according to claim 1 3 or 1 6 showing the mmHg / hr. 19. 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. 20. The magnetic recording medium according to claim 19 , which is for Hi8 for recording an analog signal, a digital video cassette recorder for recording a digital signal or 8 mm data, and for DDSIV.