JP3440182B2 - 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 electromagnetic conversion characteristics and which is useful as a base film of a magnetic recording medium having extremely few dropouts.

[0002]

2. Description of the Related Art In recent years, there have been remarkable advances in high density magnetic recording media. For example, a ferromagnetic metal thin film is formed on a non-magnetic support by a physical deposition method such as vacuum deposition or sputtering, or a plating method. Type magnetic recording media and thin layer coating type magnetic recording media in which acicular magnetic powder such as metal powder or iron oxide powder is coated to a thickness of 2 μm or less are being developed and put to practical use. Examples of the former include, for example, Co vapor deposition tape (Japanese Patent Laid-Open No. 54-147010) and a perpendicular magnetic recording medium made of Co-Cr alloy (Japanese Patent Laid-Open No. 52-134706).
(Japanese Patent Laid-Open Publication No. JP-A-2003-264), and as an example of the latter, for example, high-density magnetic recording using an ultrathin layer coating type magnetic recording medium (Technical Report of the Institute of Electronics and Communication Engineers MR94-78 (1995-02)) is known. .

A conventional coating type magnetic recording medium (a magnetic recording medium prepared by mixing magnetic powder in an organic polymer binder and coating it on a non-magnetic support) has a low recording density and a long recording wavelength. The thickness of the layer is as thick as about 2 μm or more, whereas 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. Even in the case of the layer coating type, although a non-magnetic underlayer is provided,
A thickness of μm has been proposed, and it has become extremely thin.

Therefore, in the above-mentioned high density magnetic recording medium, the surface condition of the non-magnetic support (base film) has a great influence on the surface property of the magnetic layer, especially in the case of a metal thin film type magnetic recording medium. , The surface state of the non-magnetic support is directly expressed as irregularities on the surface of the magnetic layer (magnetic recording layer).

On the other hand, from the viewpoint of handling such as film formation of the non-magnetic support (base film), conveyance in processing steps, scratches, winding, and unwinding, if the film surface is too smooth, the film-film mutual The slipperiness deteriorates, a booking phenomenon occurs, the shape when rolled into a roll (roll formation) deteriorates, and the product yield decreases,
As a result, the manufacturing cost of the product will increase. Therefore, from the viewpoint of manufacturing cost, non-magnetic support (base film)
The surface of is preferably as rough as possible.

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

Therefore, in order to manufacture a high-density magnetic recording medium of excellent quality, it is necessary to satisfy the above-mentioned contradictory properties at the same time.

As a concrete measure for this, Japanese Patent Publication No.
Japanese Patent Laid-Open No. 210833 and Japanese Patent Application Laid-Open No. 5-287101 provide a coating layer containing fine particles on one side of a polyester containing no particles.
However, this method has a problem that fine particles easily aggregate in the coating liquid, which causes dropout.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to prevent generation of agglomerated particles that cause dropout, and to improve electromagnetic conversion characteristics even when used in a base film of a vapor-deposited metal thin film type magnetic recording medium. An object of the present invention is to provide a laminated film capable of producing a magnetic recording medium which is excellent and has extremely few dropouts.

[0010]

The present invention has the following constitution in order to achieve such an object.

A laminated film in which a coating layer B containing a binder resin, a filler and a surfactant is coated on one surface of a thermoplastic resin layer A containing substantially no particles, wherein the surfactant is Surfactant X with HLB value 10-14
And a surfactant Y having an HLB value of 16 to 18.5, a total HLB value of these is 15 to 18, and the amount of the surfactant X is 0.1 to 15 relative to the solid content of the coating liquid.
%, And the amount of the surfactant Y is 10 to 40% by weight.

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

As the aromatic polyester, polyethylene terephthalate, polyethylene isophthalate,
Preferable examples include polytetramethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate, and polyethylene-2,6-naphthalene dicarboxylate. Of these, polyethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate are preferred.

These polyesters may be homopolyesters or copolyesters. In the case of copolyester, examples of the copolymerization component of polyethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate include 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, terephthalate Acid (in the case of polyethylene-2,6-naphthalenedicarboxylate), 2,6-naphthalenedicarboxylic acid (in the case of polyethylene terephthalate), other dicarboxylic acid components such as 5-sodium sulfoisophthalic acid, p- Examples include oxycarboxylic acid components such as oxyethoxybenzoic acid. The amount of these copolymerization components is preferably 20 mol% or less, more preferably 10 mol% or less.

Further, a polyfunctional compound having three or more functional groups such as trimellitic acid and pyromellitic acid can be copolymerized. In this case, it is preferable to copolymerize the polymer in a substantially linear amount, for example, 2 mol% or less.

The above polyester is known per se and can be produced by a method known per se.

In the present invention, it is necessary that the thermoplastic resin layer A contains substantially no particles. Here, the term "substantially free of particles" means that externally added particles or internal deposited particles that form protrusions on the film surface are not included, but may be generated by a catalyst essential for polymerization of polyester, for example, a lubricant action. It means that an extremely small amount of particles that do not substantially fulfill the requirement may be contained. The thermoplastic resin layer A contains other additives such as antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, etc. (excluding particles that form surface protrusions), if necessary. be able to.

When the thermoplastic resin layer A contains externally added particles or internal precipitation particles that form projections on the film surface, the surface projections due to the particles are used particularly when used as a vapor-deposited metal thin film magnetic recording medium. However, this is a defect that causes a significant deterioration in electromagnetic conversion characteristics and an increase in dropout.

The laminated film of the present invention comprises a binder resin, a filler and H on one surface of the thermoplastic resin layer A.
A coating layer B containing two kinds of surfactants having different LB values is provided. These two surfactants have an HLB value of 10-14.
And the HLB value of 16 to 18.5 and the total HLB value of 15 to 18.

Preferred examples of the binder resin include water-based polyester resin, water-based acrylic resin, water-based polyurethane resin and the like, and water-based polyester resin is particularly preferable.

The aqueous polyester resin has acid components such as 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, polyvalent carboxylic acid such as p-hydroxybenzoic acid, and the glycol component is ethylene glycol,
Diethylene glycol, propylene glycol, 1,4
-Butanediol, 1,6-hexanediol, 1,4
-A preferred example is a polyester resin mainly composed of a polyvalent hydroxy compound such as cyclohexanedimethanol, p-xylylene glycol, dimethylolpropanoic acid, and an ethylene oxide adduct of bisphenol A. Further, an acrylic polymer chain is bonded to the polyester chain. Graft polymers or block copolymers, or two polymers with specific physical composition (IPN,
It may be an acrylic-modified polyester resin having a core shell. As this water-based polyester resin,
A type that dissolves, emulsifies, and finely disperses in water can be freely used, but a type that emulsifies and finely disperses in water is preferable. Further, for imparting hydrophilicity, for example, a sulfonate group, a carboxylate group, a polyether unit or the like may be introduced into the molecule.

The type of the filler is not particularly limited, but a filler having a relatively low specific gravity that does not easily settle in the coating liquid is preferable. For example, particles made of heat resistant polymer (for example, crosslinked silicone resin, crosslinked acrylic resin, crosslinked polystyrene, melamine / formaldehyde resin, aromatic polyamide resin, polyamideimide resin, crosslinked polyester, wholly aromatic polyester, etc.), silicon dioxide (silica) ),
Preferable examples include calcium carbonate. Among these, particularly preferably, crosslinked silicone resin particles, silica, core-shell type organic particles (core: crosslinked polystyrene,
Shell: polymethylmethacrylate etc.).

These fillers have an average particle size of 10 to 50n.
m is preferable. The amount used is preferably such that the frequency of surface protrusions by the filler on the surface of the coating layer B is 2 to 20 million / mm ² . Further improvement in running durability is exhibited by this projection frequency. The average particle size of this filler is more preferably 15 to 45 n.
m, and more preferably 18 to 40 nm. The frequency of surface protrusions is more preferably 2.5 to 18 million pieces / mm ² , and even more preferably 3 to 15 million pieces / mm ² .
mm ² .

The surfactant in the present invention is, as described above, two types of surfactants having different HLB values, namely, H.
Surfactant X having an LB value of 10 to 14 and an HLB value of 16 to 18.
Consisting of 5 surfactants Y and total HLB value of 15-
18 surfactants. With only one kind of surfactant, it is not possible to solve the problems of coating such as coating loss and foam streaks due to cissing while suppressing the generation of projections derived from agglomerated particles that cause dropout.

Of the above-mentioned surfactants, H of surfactant X
The LB value is 10.5-13.5, and further 11.0-13.
It is preferably 0. HLB value of surfactant Y is 1
It is preferably 6.5 to 18.3, and more preferably 17.0 to 18.0. And H by combining these surfactants
The LB value (total HLB value) is preferably 15.5 to 17.5, and more preferably 16 to 17.5.

Here, the total HLB value is obtained by the following equation.

[0027]

[Formula 2] Total 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 relative to the total amount of surfactant HLB (Y); The HLB value P (Y) of the agent Y; the weight fraction of the total amount of the surfactant Y of the surfactant Y.

As the above-mentioned surfactant, nonionic surfactants are preferable, and those obtained by adding and binding (poly) ethylene oxide to alkyl alcohol, alkylphenyl alcohol, higher fatty acid and the like are particularly preferable.

As the surfactant X, polyoxyethylene alkylphenyl ether-based compound as nonionic NS-208.5 (HLB12.6) NS- manufactured by NOF CORPORATION
206 (HLB10.9), HS-208 (HLB1
2.6), HS-210 (HLB13.6), Octopole 60 (HLB11.3), Octapole 80 (HLB12.4), Octapole 95 (HLB) manufactured by Sanyo Kasei.
13.3), Octapole 100 (HLB13.6),
Dodecapole 90 (HLB12.0), Dodecapole 1
20 (HLB13.4), NOF P-21 manufactured by NOF CORPORATION as a polyoxyethylene alkyl ether compound
0 (HLB12.9), Sanyo Kasei's Nonipol Soft SS-50 (HLB10.5), SS-70 (HLB1)
2.8), SS-90 (HLB13.2), DO-70
(HLB12.3), DO-90 (HLB13.4),
Nonionic L-4 (HLB13.1) and S manufactured by NOF CORPORATION as polyoxyethylene ester compounds of higher fatty acids
-4 (HLB11.6), S-6 (HLB13.6) and the like can be exemplified. Further, as the surfactant Y, nonionic NS-230 (HLB manufactured by NOF CORPORATION) as a polyoxyethylene alkylphenyl ether compound is used.
17.2), NS-240 (HLB17.8), HS-
220 (HLB16.2), HS-240 (HLB1
7.9), Nonipol 200 (HLB1 manufactured by Sanyo Kasei)
6.0), Nonipol 400 (HLB17.8), Nonipol 500 (HLB18.2), Octapole 400
(HLB17.9), nonionic 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 CORPORATION as polyoxyethylene ester compounds of higher fatty acids.
18.2) etc. can be illustrated.

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 liquid. The surfactant Y is 10 to 40 per solid content of the coating liquid.
%, Preferably 12 to 36% by weight, particularly preferably 15 to 30% by weight are used.

When 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 may occur. 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 (based on total solid content),
Since the effect of lowering the surface tension of the coating liquid becomes small, coating omission occurs when the coating liquid is applied.

When the HLB value of the surfactant Y is less than 16 or the amount of the surfactant Y used is less than 10% by weight (based on the total solid content), it is impossible to suppress the generation of protrusions that may cause dropout, while the HLB value is 18%. If it exceeds 0.5, coating omission occurs, and if the amount used exceeds 40% by weight (based on the total solid content), streak-shaped coating defects due to foaming occur.

Further, when the total HLB value of the surfactant is less than 15, protrusions that cause dropout are generated, while when it exceeds 18, coating loss occurs.

In the laminated film of the present invention, it is preferable that a thermoplastic resin C containing inert particles is laminated on the other surface of the thermoplastic resin layer A. At that time, the layer thickness tc (nm) of the thermoplastic resin layer C and the average particle diameter d _C (μm) of the inert particles C having the largest average particle diameter among the inert particles contained in the thermoplastic resin layer C. And the content C _C (wt%) of the inert particles C in the thermoplastic resin layer C satisfy the following formula (1), and the air bleeding index of the laminated film is 1
It is preferably 10 mmHg / hr. This makes it possible to improve the film handling property and winding property without deteriorating the electromagnetic conversion characteristics.

[0035]

## EQU3 ## 0.1 ≦ (d _C ) ³ × C _C × t _C ≦ 10 (1) The thermoplastic resin forming the layer C may be the same as or different from the thermoplastic resin of the layer A. Of these, the same resin is preferable. Particularly, it is preferable that the layers A and C are made of polyethylene terephthalate or polyethylene-2,6-naphthalene dicarboxylate. As these polyesters, those having an intrinsic viscosity of about 0.4 to 0.9 obtained by measuring at 35 ° C. as a solution in o-chlorophenol are preferable.

The average particle size d _C of the largest particles C among the inert particles contained in the layer C is the average particle size of the single particles when the inert particles consist of one type of single particle,
When it is composed of two or more kinds of particles having different sizes, it is the average particle size of the particles having the largest average particle size.

The average particle size d _C of the largest particles is 0.
1-1 μm, more preferably 0.15-0.8 μm, especially 0.1.
It is preferably 2 to 0.7 μm. The content of the largest particles having the average particle diameter d _C is 0.0001 to 1% by weight, more preferably 0.10% by weight based on the thermoplastic resin layer C.
001 to 0.5% by weight, especially 0.005 to 0.1% by weight
Is preferred.

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

Further, when the inert particles are composed of two or more kinds of particles, as the second and third particles having an average particle size smaller than the average particle size d _C of the largest particles, for example, colloidal silica, α Fine particles of alumina or the like having a crystal form of γ, δ, θ or the like can be preferably used. Further, among the particle types exemplified as the inert particles having the average particle diameter d _C , fine particles having a small average particle diameter can be used.

The average particle size of the fine particles is 5 to 400 n.
m, more preferably 10 to 300 nm, particularly 30 to 250 nm, and smaller than the average particle diameter d _C by 50 nm or more, further 100 nm or more, and particularly preferably 150 nm or more. The content of the second and third particles (fine particles) is 0.005 to 1% by weight, further 0.01 to 0.7% by weight, and particularly 0.05 to 100% by weight based on the thermoplastic resin layer C.
It is preferably 0.5% by weight.

In the present invention, the total thickness of the laminated film is
Usually 2.5 to 20 μm, preferably 3.0 to 10 μm,
More preferably, it is 4.0 to 10 μm. The layer thickness of the thermoplastic resin layer C is 1/2 or less of the total thickness of the laminated film,
Further, it is preferably 1/3 or less, and particularly preferably 1/4 or less. The layer thickness of the coating layer B is 1 to 100 nm, and further 2
.About.50 nm, particularly 3 to 10 nm, preferably 3 to 8 nm.

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

For example, a biaxially oriented polyester film will be described. The polyester A and the inert particles C are contained in the extrusion die or before the die (generally, the former is called a multi-manifold method, the latter is called a feed block method). Polyester C is laminated and composited in a molten state to form a laminated structure having the above-mentioned suitable thickness ratio, and then coextruded from the die at a temperature of melting point Tm (° C) to (Tm + 70) ° C into a film, and then 40 to It is rapidly cooled and solidified with a 90 ° C. cooling roll to obtain an unstretched laminated film. Thereafter, the unstretched laminated film was uniaxially (longitudinal or transversely) uniaxially (Tg-10) to (Tg + 70) at a temperature (however, T
g: glass transition temperature of the polyester) 2.5 to 8.
The film is stretched at a draw ratio of 0 times, preferably at a draw ratio of 3.0 to 7.5 times, and then stretched in a direction perpendicular to the direction from Tg to (Tg + 7.
0) Stretching at a temperature of 2.5 ° C. to 8.0 times, preferably 3.0 to 7.5 times. Further, if necessary, it may be stretched again in the machine direction and / or the transverse direction. That is,
It is advisable to perform stretching in two stages, three stages, four stages, or multiple stages. The total draw ratio is usually 9 times or more, preferably 12 to 35 times, more preferably 15 to 30 times as an area draw ratio. Subsequently, a biaxially oriented film (Tg + 7
0) to (Tm-10) ° C., for example 180 to 250
Excellent dimensional stability is imparted by heat-fixing crystallization at ° C. The heat setting time is preferably 1 to 60 seconds.

In the above method, a coating liquid containing the above-mentioned filler, binder resin, surfactant X and surfactant Y, preferably an aqueous coating liquid, is applied. The coating is preferably performed on the surface of the polyester A before the final stretching treatment, and after the coating, the film is stretched in at least a uniaxial direction. The coating film is dried before or during this stretching. Among them, the coating is preferably performed on an unstretched laminated film or a longitudinal (uniaxial) stretched laminated film, particularly a longitudinal (uniaxial) stretched laminated film. The coating method is not particularly limited,
For example, a roll coating method, a die coating method and the like can be mentioned.

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, and especially 0.1.
It is preferably from 5 to 4% by weight. Then, other components such as other surfactants, stabilizers, dispersants, UV absorbers, thickeners, etc. are added to the coating liquid (preferably aqueous coating liquid) within a range that does not impair the effects of the present invention. can do.

The above examples are suitable when the thermoplastic resin layers A and C are both polyethylene-2,6-naphthalene dicarboxylate or polyethylene terephthalate, but only the layer A or the layer C is polyethylene-2. 6-
The same applies to the case of naphthalene dicarboxylate or polyethylene terephthalate.

In the production of the laminated film, the thermoplastic resin may optionally contain additives other than the above-mentioned inert particles such as stabilizers, colorants, and specific resistance adjusting agents for molten polymers.

In the present invention, in order to improve various performances such as head touch as a magnetic recording medium and running durability, and at the same time to achieve a thin film, the Young's modulus of the laminated film is changed in the longitudinal direction and the transverse direction, respectively. 450 kg / mm ² or more, 600 kg / mm ² or more, and further 480 kg / mm
² or more, 680 kg / mm ² or more, especially 550 kg / m
m ² or more, 800 kg / mm ² or more, especially 550 kg /
It is preferably at least ² mm ^{2 and at} least 1000 kg / mm ² . Further, the crystallinity of the polyethylene terephthalate layer is preferably 30 to 50%, and the crystallinity of the polyethylene-2,6-naphthalene dicarboxylate layer is preferably 28 to 38%. If both are below the lower limit, the heat shrinkage ratio will be large, whereas if it is above the upper limit, the abrasion resistance of the film will be deteriorated and white powder tends to be generated when sliding on the surface of the roll or the guide pin.

The laminated film of the present invention has a strong strength of iron, cobalt, chromium or an alloy or oxide containing these as the main components on the surface of the coating layer B by a method such as vacuum deposition, sputtering or ion plating. A magnetic metal thin film layer is formed, and a protective layer such as a diamond-like carbon (DLC) is formed on the surface of the magnetic metal thin film layer according to the purpose, application, and need.
By providing a fluorinated carboxylic acid type lubricating layer in sequence and further providing a known back coat layer on the surface of the thermoplastic resin layer B side, output in a short wavelength region, electromagnetic conversion characteristics such as S / N and C / N It is possible to provide a vapor-deposited magnetic recording medium for high density recording which is excellent in dropout and has a small error rate. This vapor-deposited magnetic recording medium is used for recording analog signals.
It is extremely useful as a magnetic tape for i8, digital video cassette recorder (DVC) for recording digital signals, data 8 mm, and DDSIV.

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

The laminated film of the present invention also has a coating layer B
On the surface of, acicular fine magnetic powder such as iron oxide or chromium oxide,
Alternatively, a plate-like fine magnetic powder such as barium ferrite is uniformly dispersed in a binder such as polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, etc., and applied so that the magnetic layer thickness is 1 μm or less, preferably 0.1 to 1 μm. By further providing a back coat layer on the surface of the thermoplastic resin layer C side by a known method, the output, S / N, C
It is possible to obtain a coating type magnetic recording medium for high density recording which is excellent in electromagnetic conversion characteristics such as / N and has less dropout and error rate. Further, if necessary, a nonmagnetic layer containing fine titanium oxide particles or the like is dispersed as an underlayer of the metal powder-containing magnetic layer in the same organic binder as the magnetic layer and coated on the layer C. You can also do it. The oxide coated magnetic recording medium is useful as a high density oxide coated magnetic recording medium such as a QIC for a data streamer for digital signal recording.

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

[0053]

EXAMPLES The present invention will be specifically described below with reference to examples. The measuring methods and definitions used in the present invention are as follows.

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

(2) Average particle size I of particles (average particle size: 0.
Shimadzu CP-50 Centrifugal Particle Size Analyzer (Centrifugal Particles)
Size analyzer). The particle diameter "equivalent sphere diameter" corresponding to 50 mass% is read from the integrated curve of the particles having respective particle diameters calculated based on the obtained centrifugal sedimentation curve and the abundance thereof, and this value is taken as the above average particle diameter. (Book
"Particle size measurement technology", Nikkan Kogyo Shimbun, 1975, p. 2
42-247).

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

(4) HLB value

[0058]

[Equation 4]

Here, M: molecular weight of the surfactant Mn: molecular weight of the hydrophilic group portion. [Refer to "Oil Chemistry" 13 , 220 (1964)]

(5) Layer Thickness The total thickness of the thermoplastic resin layers A and C and the total thickness of the film are randomly measured at 10 points with a micrometer, and the average value thereof is used. The thicknesses of the layers A and C are determined by measuring the layer thickness on the thin side by the method described below, and the layer thickness on the thick side is obtained by subtracting the coating layer B and the layer thickness on the thin side from the total thickness. That is, by using a secondary ion mass spectrometer (SIMS), the concentration of the element derived from the highest concentration of particles in the film in the depth range of 5000 nm from the surface layer excluding the coating layer and the carbon element of the polyester The ratio (M ⁺ / C ⁺ ) is the particle concentration and the depth from the surface is 5
Analyze in the thickness direction up to 000 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, the particle concentration once reaches a stable value of 1, then rises or decreases to reach a stable value of 2, and sometimes monotonically decreases. Based on this distribution curve, in the former case, (stable value 1 + stable value 2) /
A layer of the layer with a depth giving a particle concentration of 2 and, in the latter case, a depth at which the particle concentration is 1/2 of a stable value of 1 (this depth is deeper than the depth giving a stable value of 1). The thickness was used.

The measurement conditions are as follows. Measuring instrument Secondary ion mass spectrometer (SIMS); PERKIN
ELMER 6300 Measurement conditions Primary ion species: O ₂ + Primary ion accelerating voltage: 12 KV Primary ion current: 200 nA Raster region: 400 μm □ Analysis region: Gate 30% Measuring vacuum degree: 6.0 × 10 ^-9 Torr E-GUNN : 0.5KV-3.0A If the most contained particles in the range of 5000 nm from the surface layer are organic polymer particles other than silicone resin, SI
Since it is difficult to measure with MS, the same concentration distribution curve as above is measured with FT-IR (Fourier Transform Infrared Spectroscopy) or XPS (X-ray High Electron Spectroscopy) depending on the particle while etching from the surface. Find the thickness.

(6) Frequency of protrusions by the filler on the surface of the coating layer B The frequency of protrusions on the surface of the film is measured by a scanning electron microscope. That is, 25 surface photographs 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, the average value was converted into the number of protrusions per 1 mm ² , and this value was applied. The protrusion frequency of the filler on the surface of the film layer B is used.

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

[0064]

[Equation 5]

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

(8) Young's modulus Using a tensile tester Tensilon manufactured by Toyo Baldwin Co., Ltd., a sample film having a length of 300 mm and a width of 12.7 mm was prepared in a room controlled at a temperature of 20 ° C. and a humidity of 50%. Tensile at a strain rate of 10% / min, calculated using the first linear part of the tensile stress-strain curve according to the formula:

[0067]

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

(9) Air bleeding property Using a Divec smoothness tester manufactured by Toyo Seiki Co., Ltd.
First, 40 sheets of film are superposed, one of them is placed at the top of the sample table, and the remaining 39 sheets are perforated with a diameter of 5 mmφ and set on the sample table. At this time, the center of the hole should be located at the center of the sample table. 0.5kg /
A load of cm ² is applied, and the degree of vacuum achievement is set to 550 mmHg. After reaching 550 mmHg, the air tries to return to the normal pressure, so that the air flows between the films. At this time, the degree of vacuum (mmHg) that drops every 30 seconds during one hour is measured, and the inclination of the straight line when the degree of vacuum is linearly approximated with respect to the measurement time (hr) (= mmHg / h
Let r) be the air leak index G.

(10) The number of fine protrusions The surface of the coating layer B having a thickness of 0.5 μm vapor-deposited thereon was observed by an optical microscope NIKON OPTIPHOT at a magnification of 400 times by a differential interference method, and the longitudinal direction was 2 μm. B. Count the number of protrusions having a size of 5 μm or more in the width direction and convert them into the number per 1 mm ² .

(11) Omission of coating, immersion with a coating layer B for coating on the lower side, immersion in a dyeing solution of the following composition (temperature: 50 ° C.) for 10 minutes, washing with water, and visual observation. If there is a non-existing region, the application is skipped, and if there is a streak in the longitudinal direction, the application streak is determined.

(12) Manufacture of magnetic tape and evaluation of characteristics On the surface of the coating layer B of the biaxially oriented laminated film, a ferromagnetic thin film of 100% cobalt of 0.02 μm was formed by a vacuum deposition method.
Of 2 layers (each layer thickness is about 0.1 μm) and diamond-like carbon (DLC) is formed on the surface.
A film and a fluorinated carboxylic acid-based lubricating layer are sequentially provided, and a back coat layer is provided on the surface of the thermoplastic resin layer A or C side by a known method. After that, it is slit into a width of 8 mm and loaded into a commercially available 8 mm video cassette. The tape properties are then measured using the following commercially available equipment.

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

C / N measurement recording A signal having a wavelength of 0.5 μm (frequency of about 7.4 MHz) was recorded, and the ratio of the reproduced signal of 6.4 MHz and the value of 7.4 MHz was used as the C / N of the tape. The C / N of the vapor deposition tape for 8 mm video is set to 0 dB, and judgment is made according to the following criteria.

[0074]

Dropout Using a dropout counter manufactured by Shibasoku Co., Ltd., a dropout of 3 μsec / 10 dB or more is applied to 10 times.
Measure for minutes and convert to the number per minute. Judge according to the following criteria.

◯: Dropout 10 or less per minute ×: 11 or more dropouts per minute

[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 silicone resin particles for layer C as a lubricant. (0.5μφ) and θ-alumina particles (0.04μφ) 0.02 wt% (relative to polyester) and 0.20 wt% (relative to polyester)
And added thereto so as to be polymerized by an ordinary method to obtain an intrinsic viscosity of 0.
Polyethylene terephthalate (PET) for layers A and C (resin A, resin C) was obtained.

Each of the resins A and C was dried at 170 ° C. for 3 hours, then fed to two extruders and melted at a temperature of 28.
The resin layer C was melted at 0 to 300 ° C., and the resin layer C was laminated on one surface of the resin layer A using a multi-manifold type coextrusion die, and was rapidly cooled to obtain an unstretched laminated film having a thickness of 136 μm.

The obtained unstretched film was preheated, and the film temperature was set to 3.3 at a film temperature of 100 ° C. between low speed and high speed rolls.
The film is double-stretched, rapidly cooled, and then on the layer A side of the longitudinally stretched film, the binder resin and the core-shell organic filler shown in Table 1 (core: cross-linked polystyrene shell: acrylic 25 mm).
φ) 6% by weight (based on the total solid content), an aqueous coating solution containing the surfactant shown in Table 1 (total solid content concentration 1.0% by weight) was applied by a kiss coating method, and subsequently supplied to a stenter, 1
It was stretched 4.2 times in the transverse direction at 10 ° 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 thickness of layers A and C was adjusted by the discharge amount of the two extruders. The Young's modulus of this film is 5 in the vertical direction.
00kg / mm ^2, was transverse 700 kg / mm ^2. The filler frequency on the surface of layer B is 10 million pieces / mm
^{Was 2} .

Table 2 shows the surface characteristics of this laminated biaxially oriented film and the characteristics of the ferromagnetic thin film deposition type magnetic tape using this film.

[Comparative Example 1] A laminated film was obtained in the same manner as in Example 1 except that the particles shown in Table 1 were added to the thermoplastic resin layer A. Table 2 shows the characteristics of the obtained film and the characteristics of the ferromagnetic thin film deposition type magnetic tape using this film.

[Example 2, Comparative Examples 2 to 4] The type and content of the binder and / or the surfactant in the coating layer B and the layer thickness of the thermoplastic resin layer A are changed as shown in Table 1. A laminated biaxially oriented polyester film was obtained in the same manner as in Example 1 except for the above.

Table 2 shows the characteristics of the films thus obtained and the characteristics of the ferromagnetic thin film vapor-deposited magnetic tape using these films.

[Examples 3 to 5 and Comparative Example 5] A layer A and a layer C were prepared in the same manner as in Example 1 except that the same molar amount of dimethyl 2,6-naphthalenedicarboxylate was used instead of dimethyl terephthalate. Polyethylene-2,6-naphthalate (PEN) (resin A, resin C) was obtained.

Each of the resins A and C was dried at 170 ° C. for 6 hours, and the thickness of each layer was adjusted in the same manner as in Example 1 to obtain an unstretched laminated film satisfying each example and comparative example.

The unstretched film thus obtained is preheated, and the film temperature is set to 135 between the low speed and high speed rolls.
At 0 ° C., it was stretched to 4.0 times in Example 3, 3.6 times in Examples 4 and Comparative Example 5, 3.3 times in Example 5 and quenched, and then the coating layer B shown in Table 1 was drawn. Was applied in the same manner as in Example 1 and subsequently supplied to a stenter, and the horizontal direction at 155 ° C. was 5.2 times in Example 3, 5.6 times in Example 4 and Comparative Example 5, In Example 5, the film was stretched 6.4 times. The obtained biaxially stretched film was heat set with hot air at 200 ° C. for 4 seconds to obtain a laminated film.

Table 2 shows the characteristics of the films thus obtained and the characteristics of the ferromagnetic thin film deposition type magnetic tape using these films.

[Comparative Example 6] Without providing the thermoplastic resin layer C,
A laminated film was obtained in the same manner as in Example 4, except that the kind and content of the surfactant were changed as shown in Table 1.

Table 2 shows the characteristics of the films thus obtained and the characteristics of the ferromagnetic thin film vapor-deposited magnetic tape using these films.

[0090]

[Table 1]

[0091]

[Table 2]

As is clear from Table 2, the film according to the present invention not only exhibits excellent electromagnetic conversion characteristics, but also has extremely few fine protrusions that cause dropouts, and has no defects such as coating omissions and coating streaks. . On the other hand, those which do not satisfy the requirements of the present invention cannot satisfy these characteristics at the same time.

[0093]

EFFECTS OF THE INVENTION According to the present invention, the surface of the coating layer B has no protrusions that cause dropout, and the electromagnetic conversion characteristics,
It is possible to provide a laminated film useful for producing a magnetic recording medium having excellent running properties.

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-6-145390 (JP, A) JP-A-8-142292 (JP, A) JP-A-7-304144 (JP, A) JP-A-4- 276439 (JP, A) Patent 3258259 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 C08J 7/04 G11B 5/73-5/738

Claims (8)

(57) [Claims] 1. A laminated film having a coating layer B containing a binder resin, a filler and a surfactant applied on one surface of a thermoplastic resin layer A which does not substantially contain particles. The agent contains a surfactant X having an HLB value of 10 to 14 and a surfactant Y having an HLB value of 16 to 18.5, and the total HLB value of these is 15 to 18, and the solid content of the coating liquid is The amount of surfactant X is 0.1 to 1
5% by weight, and the amount of the surfactant Y is 10 to 40% by weight, a laminated film. 2. The HLB value of the surfactant X is 10.5-1.
3. The laminated film according to claim 1, wherein the amount is 3.5 to 10% by weight (based on the solid content of the coating liquid). 3. The HLB value of the surfactant Y is 16.5 to 1.
2. The laminated film according to claim 1, wherein the amount is 12 to 36% by weight (based on the solid content of the coating liquid). 4. The laminated film according to claim 1, wherein the binder resin is an aqueous polyester resin, and the filler is heat-resistant polymer particles having an average particle size of 10 to 50 nm. 5. The laminated film according to claim 1, wherein the frequency of protrusions by the filler on the surface of the coating layer B is 2,000,000 to 20,000,000 pieces / mm ² . 6. A thermoplastic resin layer C containing inert particles is laminated on the other surface of the thermoplastic resin layer A to form a layer C.
Thickness t _C (nm) and the average particle size d _C (nm) of the particles C having the largest average particle size among the inert particles and the particle C
Content C _C (% by weight) satisfies the following formula (1), and the air release index of the laminated film is 1 to 10 mmHg /
The laminated film according to claim 1, which is hr. ## EQU1 ## 0.1 ≦ (d _C ) ³ × C _C × t _C ≦ 10 (1) 7. The laminated film according to claim 1, wherein the thermoplastic resin is an aromatic polyester. 8. The average particle diameter d _C of the inert particles _C is 0.1 to 10.
The laminated film according to claim 6, which has a thickness of 1 μm.