JP2000037838A - Composite polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite polyester film reduced in charge quantity, not generating blocking between films, reduced in shaving and suitable for a base material for a high density magnetic recording medium. SOLUTION: A composite polyester film is constituted by providing a film layer A consisting of a binder resin, inert particles, a surfactant and a siloxane copolymerized acrylic resin on at least the single surface of a polyester film being a base film. In this case, the content of the siloxane copolymerized acrylic resin in the film layer is 1-50 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a composite polyester film. For details, the charge amount of the film is small,
Composite polyester with no blocking between films, little scraping, and excellent electromagnetic conversion properties, adhesiveness of magnetic recording layer, and adhesiveness of back coat layer, especially suitable for use as a base material for high density magnetic recording media About the film.

[0002]

2. Description of the Related Art A magnetic recording medium such as a video tape, an audio tape, a memory tape, a magnetic sheet, and a magnetic disk comprises a support and a magnetic layer (magnetic recording layer) provided on the surface of the support. In addition, a magnetic tape is often provided with a slippery back coat layer on the surface opposite to the magnetic layer in order to increase slipperiness. As a support for magnetic recording media,
Although a polyester film is mainly used, the adhesion between the magnetic layer and the polyester film and the adhesion between the slippery back coat layer and the polyester film are important characteristics. If the adhesion is poor, recording of the magnetic recording medium,
During the recording / reproducing process, the magnetic layer and the back coat layer are peeled off, and the magnetic recording characteristics are completely impaired.

[0003] Several types of films are known as polyester films having improved adhesion. For example,
Examples thereof include those having a surface subjected to corona discharge treatment and those having an easily adhesive resin applied to the surface. It is even said that it is desirable to apply an easy-adhesion resin in order to provide a particularly remarkable easy-adhesion effect.

[0004] In recent years, as the density of magnetic recording has increased, the surface roughness of the polyester film used has been reduced and smoothed. In this case, in the case where the conventional easy-adhesive resin coating treatment is applied, when the film is wound into a roll state, blocking between the films occurs, and the film breaks at the unwinding stage of the magnetic recording medium manufacturing process of the roll. It is easy to break or torn.

[0005] In particular, a vapor-deposited magnetic recording medium in which a magnetic metal thin film is provided on a polyester film surface by vacuum vapor deposition, for example, a vapor-deposited tape for video, has a low surface roughness of a base film to be used. It is necessary to improve the slipperiness of the tape running surface by providing a back coat layer on the tape.

[0006] In this case, when the back coat layer is subjected to a conventional coating process for improving the adhesion of the back coat layer to the polyester film, the surface roughness of the film is extremely low. Because it is low, blocking tends to occur.

[0007] This blocking is considered to occur because moisture in the air permeates into the film surfaces or enters between the surfaces, and the pressure between the films causes the film surfaces to be in an adhesive state. The factory stores rolled products under low humidity after film production or before use, and it is possible to prevent blocking to some extent by strictly controlling storage control conditions, but an essential solution can be achieved. Absent. In particular, in the case of a polyester film for a vapor-deposited magnetic recording medium, it is impossible to prevent blocking of the easily adhesive film by controlling the humidity.

[0008] The polyester film which has been subjected to the easy adhesion treatment is easily charged. A highly charged film may significantly deteriorate the handling properties during film formation and tape formation, and the spark generated by charging may ignite the organic solvent used during tape formation, and furthermore, the film may float in the air. Dust is easily attracted electrically, and such a dust has a problem that it causes dropout particularly for a vapor-deposited tape or the like that requires high-density recording.

In the production of a vapor deposition type magnetic recording medium, in order to improve the adhesion between the metal thin film and the base film, the surface of the base film is activated by ions, usually called an ion bombardment treatment, before forming the metal thin film. Processing is performed. And when forming a thin film, high temperature heat is applied to the film surface, and the base film may melt,
Alternatively, the back surface is cooled so that the physical properties such as the mechanical characteristics do not decrease. As a method of cooling the back surface, a method of winding a base film around a drum-shaped cooling body is usually used. At this time, both ends of the base film are masked so that a metal thin film is not formed on the drum surface. Therefore, both ends of the processed film after the vapor deposition process are subjected to only the ion bombardment process in the longitudinal direction of the film, and become a portion where the metal thin film is not formed, which continuously occurs, and this portion is formed with both edge portions of the film roll. Become. When this portion is wound up, the base surface activated by the ion bombardment treatment comes into contact with the base surface on the opposite side, so that blocking tends to occur, causing a process trouble.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, and has a small charge amount of a film, no blocking between films, little shaving, electromagnetic conversion characteristics, and adhesion of a magnetic layer. It is an object of the present invention to provide a composite polyester film having excellent properties and adhesiveness of a back coat layer, and particularly suitable for use as a substrate of a high-density magnetic recording medium.

[0011]

According to the present invention, a polyester film is used as a base film, and at least one surface of the film has a binder resin, inert particles, a surfactant and a siloxane copolymerized acrylic resin. This is achieved by a composite polyester film having a coating layer A comprising a siloxane copolymerized acrylic resin in the coating layer A having a content of 1 to 50% by weight.

The present invention will be described in detail below. As the polyester constituting the base film in the present invention,
Polyethylene terephthalate, polyethylene isophthalate, polytetramethylene terephthalate, poly-1,
4-cyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate and the like can be exemplified. Of these, polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate are preferred.

The polyester may be a homopolyester or a copolyester. In the case of a copolyester, as a copolymer component of polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate, for example, diethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, neopentyl glycol, polyoxyethylene glycol, p- Other diol components such as xylene glycol and 1,4-cyclohexanedimethanol, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid (however, in the case of polyethylene-2,6-naphthalenedicarboxylate), 2, 6-Naphthalenedicarboxylic acid (however, in the case of polyethylene terephthalate) 5-
Other dicarboxylic acid components such as sodium sulfoisophthalic acid, and oxycarboxylic acid components such as p-oxyethoxybenzoic acid are included. The amount of the copolymer component is preferably at most 20 mol%, more preferably at most 10 mol%, based on the total acid components.

Further, a trifunctional or higher polyfunctional compound such as trimellitic acid or 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.

It will be readily understood that copolymer components other 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 intrinsic viscosity of the polyester is preferably in the range of 0.4 to 0.9.

The thickness of the polyester film (base film) in the present invention is 1 to 20 μm, preferably 2 to 20 μm.
10 μm.

The polyester film (base film) in the present invention may or may not contain inert particles. When it is contained, it may be organic particles or inorganic particles. The inert particles (inactive particles P) to be contained in the polyester film are different from the inert particles used for the later-described coating layer A, coating layer B or coating layer C, even if they have the same type and average particle size. Is also good.

In the inert particles P, organic particles include polystyrene, polystyrene-divinylbenzene, polymethyl methacrylate, methyl methacrylate copolymer, cross-linked methyl methacrylate copolymer, polytetrafluoroethylene, polyvinylidene fluoride,
Examples include particles composed of polyacrylonitrile, benzoguanamine resin, silicone resin, and particles having a core-shell structure composed of a graft copolymer containing these polymers as components. Examples of the inorganic particles include particles made of silica, alumina, titanium dioxide, feldspar, kaolin, talc, graphite, calcium carbonate, molybdenum disulfide, carbon black, and barium sulfate. These particles are usually used during the production of polyester, for example, at any time during the transesterification reaction or polycondensation reaction in the case of the transesterification method, or at any time in the case of the direct polymerization method, preferably in the reaction system as a glycol slurry. Added.

The average particle size of the inert particles P is usually 2 μm.
m or less, but when the coating layer A forms the surface on the nonmagnetic layer side, the thickness is preferably 0.005 to 2 μm (5 to 2000 nm), more preferably 0.01 to 1.8 μm. The amount is preferably from 0.001 to 2% by weight, more preferably from 0.01 to 1.5% by weight, based on the weight of the polyester. The average particle size of the inert particles P is as follows.
To form a surface on the side of the magnetic layer,
Further, the thickness is preferably from 40 to 200 nm, particularly preferably from 50 to 120 nm, and the amount of addition is 50,000 to 100,000 / mm ² , more preferably 0.75 to 60,000 / m ^{2 on the} film surface.
It is preferable that the amount is such that microprojections are formed at a density of m ² , especially 10,000 to 30,000 / mm ² . When the density of the fine protrusions is in the above range, satisfactory running durability and excellent electromagnetic conversion characteristics on the surface of the magnetic layer can be obtained.

The volume shape factor (f) of the inert particles P is arbitrary, but is preferably 0.1 to π / 6 when the coating layer A forms the surface on the magnetic layer side. Preferably it is 0.4 to π / 6.

This volume shape factor (f) is given by the following equation:

[0023]

F = V / R ³ [where f is the volume shape factor and V is the volume of the particles (μ
m ³ ) and R are the average particle size (μm) of the particles. ]. A shape having a coefficient (f) of π / 6 is a sphere (true sphere). The shape having the 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.

The polyester film in the present invention may have a single-layer structure or a multilayer structure composed of two or more polyester films each having a different composition.

In the present invention, when the coating layer A forms the surface on the magnetic layer side, the surface of the polyester film has a roughness of at least 4 nm in height calculated from a surface roughness profile obtained by a non-contact three-dimensional roughness meter. Protrusions are 200 / mm
The density is preferably ² or less. When the density of the coarse protrusions exceeds 200 / mm ² , the protrusions themselves cause a dropout, and when the coarse protrusions are caused by poor dispersion of the inert particles P, uneven wear of the head is liable to occur. Is also undesirably deteriorated.

In order to enhance the dispersibility of the inert particles P in the polyester, for example, a method of optimizing the timing of charging the polyester as a glycol slurry during the polymerization of the polyester and a method of optimizing the charging speed of the glycol slurry It is preferable to use high precision filtration before extruding the molten polymer from the extrusion die during film formation. In this high-precision filtration, it is preferable that the average mesh size of the filter, especially the metal fiber sintered filter, is 10 times or less, more preferably 5 times or less the average particle size of the inert particles P. 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 coating layer A in the present invention comprises a binder resin, inert particles, a surfactant and a siloxane copolymerized acrylic resin. The surface tension of the outer surface of the coating layer A is 45 dyn / cm or more, and furthermore, 45 to 53 dyn.
/ Cm.

As the binder resin constituting the coating layer A, alkyd resin, phenol resin, epoxy resin, amino resin, polyurethane resin, cellulose resin,
Examples thereof include a vinyl acetate resin and a vinyl chloride-vinyl acetate copolymer. Water-soluble or water-dispersible resins such as acrylic resins, polyester resins, and acryl-polyester resins are preferred from the viewpoints of adhesion to the polyester film, protrusion retention, and slipperiness. These resins may be a homopolymer or a copolymer, or may be a mixture.

These resins have a softening point (measured with a dried binder resin) of 50 ° C. measured according to JIS K-7206 in order to improve blocking resistance.
It is preferable that it is above. However, if the Tg of the binder resin of the coating layer A is too high, the surface of the coating layer A may be rough and the electromagnetic conversion characteristics may be poor depending on the coating conditions and the like. Therefore, when a binder having a high Tg is used, it is desired to devise coating conditions so as not to roughen the surface. The roughness in this case refers to a root-mean-square roughness measured at 10 μm square by AFM (scanning atomic force microscope), preferably 2.0 μm or less, more preferably 1.8 nm or less, particularly preferably. Is 1.5
nm or less. The content of the binder resin is preferably 20 to 90% by weight based on the weight of the coating layer A.

The water-soluble or water-dispersible acrylic resin is, for example, an acrylate ester (alcohol residues such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl). Butyl group, 2
-Ethylhexyl group, cyclohexyl group, phenyl group,
Benzyl group, phenylethyl group, etc.); methacrylic acid ester (the alcohol residue is the same as above);
Hydroxy-containing monomers such as -hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate; acrylamide, methacrylamide, N-methylmethacrylamide, N-methylacrylamide, N-methylolacrylamide; Amide group-containing monomers such as N-methylol methacrylamide, N, N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-phenylacrylamide; N, N-diethylaminoethyl acrylate, N, N An amino group-containing monomer such as diethylaminoethyl methacrylate; an epoxy group such as glycidyl acrylate or glycidyl methacrylate; Or a sulfonic acid group such as styrene sulfonic acid, vinyl sulfonic acid and salts thereof (eg, sodium salt, potassium salt, ammonium salt, etc.) or an acrylic monomer such as a monomer. Monomers containing salts; crotonic acid, itaconic acid, acrylic acid, maleic acid, fumaric acid and their salts (eg sodium salt,
A monomer containing a carboxyl group or a salt thereof such as potassium salt, ammonium salt, etc .; a monomer containing an anhydride such as maleic anhydride or itaconic anhydride; other vinyl isocyanate, allyl isocyanate, allyl glycidyl ether, styrene, vinyl Methyl ether,
Monomers of vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate, vinyl chloride, etc. )
It is preferably made of a combination of (meth) acrylic monomer such as acrylic acid derivative and methacrylic acid derivative in an amount of 50 mol% or more,
Particularly, those containing a component of methyl methacrylate are preferred.

The water-soluble or water-dispersible acrylic resin can be self-crosslinked with a functional group in the molecule, or can be crosslinked with a crosslinking agent such as a melamine resin or an epoxy compound. Examples of the acid component constituting the water-soluble or water-dispersible polyester resin in the present invention include terephthalic acid, isophthalic acid, phthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid,
4'-diphenyldicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, succinic acid, 5-sodium sulfoisophthalic acid, 2-potassium sulfoterephthalic acid, trimellitic acid, trimesic acid, trimellitic anhydride, phthalic anhydride, Examples thereof include polyvalent carboxylic acids such as p-hydroxybenzoic acid and monopotassium trimellitate. Further, as the hydroxy compound component, for example, ethylene glycol, propylene glycol, 1,
3-propanediol, 1,4-butanediol, 1,
6-hexanediol, neopentyl glycol, 1,
4-cyclohexanedimethanol, p-xylylene glycol, ethylene oxide adduct of bisphenol A,
Examples include polyhydroxy compounds such as diethylene glycol, triethylene glycol, polyethylene oxide glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, and potassium dimethylolpropanoate. it can. A polyester resin can be prepared from these compounds by a conventional method. From the viewpoint of preparing an aqueous paint, it is preferable to use an aqueous polyester resin containing a 5-sodium sulfoisophthalic acid component or a carboxylate group. Such a polyester resin can be a self-crosslinking type having a functional group in the molecule, or can be crosslinked using a curing agent such as a melamine resin or an epoxy resin.

In the present invention, the water-soluble or water-dispersible acryl-polyester resin is used to mean an acrylic-modified polyester resin and a polyester-modified acrylic resin, and the acrylic resin component and the polyester resin component are bonded to each other. And includes, for example, a graft type and a block type. Acrylic-polyester resins, for example, add a radical initiator to both ends of the polyester resin to cause polymerization of the acrylic monomer, or add a radical initiator to the side chain of the polyester resin to polymerize the acrylic monomer. Alternatively, it can be produced by attaching a hydroxyl group to the side chain of the acrylic resin and reacting it with a polyester having an isocyanate group or a carboxyl group at a terminal to obtain a comb polymer.

The material of the inert particles (inert particles A) used for forming the coating layer A includes polystyrene, polystyrene-divinylbenzene, polymethyl methacrylate, methyl methacrylate copolymer, methyl methacrylate copolymer crosslinked product, Organic polymers such as polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, benzoguanamine resin, silicone resin, silica, alumina, titanium dioxide, kaolin, talc, graphite, calcium carbonate, feldspar, molybdenum disulfide, carbon black, sulfuric acid Any of inorganic compounds such as barium may be used. Alternatively, core-shell type particles having a multilayer structure composed of substances having different properties inside and outside may be used.

The average particle size of the inert particles A is 10 to 200 nm when the coating layer A forms the surface on the nonmagnetic layer side.
Further, it is preferably 20 to 100 nm, and the content in the coating layer A is 5 to 40% by weight, more preferably 5 to 20% by weight.
% By weight. It is preferable that the particle size distribution is uniform. If the average particle size is less than 10 nm or the content is less than 5% by weight, the winding property of the film, the transportability in the film forming process is insufficient, and blocking is liable to occur. On the other hand, when the average particle size exceeds 200 nm or when the content exceeds 40% by weight, there is a problem that the coating layer A is easily shaved. The average particle size of the inert particles A is 10 when the coating layer A forms the surface on the magnetic layer side.
５０50 nm, furthermore 15-45 nm, especially 18-40 n
m, and the content in the coating layer A is preferably 0.5 to 30% by weight, more preferably 2 to 20% by weight. When the average particle size is less than 10 nm or the amount added is less than 0.5% by weight, good running durability of the magnetic layer cannot be obtained. On the other hand, when the average particle size exceeds 50 nm or the amount added exceeds 30% by weight. Is not preferred because the electromagnetic conversion characteristics deteriorate.

In the present invention, the center line average roughness Ra ^A of the outer layer surface on which the coating layer A is formed is 1 to 30 nm when the coating layer A forms the surface on the non-magnetic layer side, and more preferably 2 to 20 nm.
It is preferred that When the Ra ^A is less than 1 nm, the winding property of the film and the transportability in the film forming process become insufficient, and blocking tends to occur. On the other hand, Ra ^A is 3
When the thickness exceeds 0 nm, the coating layer A is easily scraped,
There is a problem that the shape is transferred to the other surface when wound into a roll. The roughness may be provided by the coating layer A, may be provided by a polyester film, or may be provided by a cooperative effect of the coating layer A and the polyester film.

[0036] The center line average roughness Ra ^A of the outer surface to form a coating layer A in the present invention, 0.1 to 2 nm when the film layer A to form a magnetic layer side, even 0.5
It is preferably about 1.5 nm. In this case, on the outer surface of the coating layer A, projections caused by the inert particles A contained in the coating layer A are preferably 1 to 40 / μm ² , more preferably 2 to 20 / μm ^2. And particularly preferably 2.
5 to 18 pieces / [mu] m ^2, is present at a density of especially 3-15 / [mu] m ^2. On the outer surface of the coating layer A, coarse projections having a height of 4 nm or more calculated from a surface roughness profile determined by a non-contact three-dimensional roughness meter are preferably 200 / projections.
It may exist at a density of not more than mm ² , more preferably at most 100 / mm ² , and excellent running durability is exhibited by the presence of the protrusions.

In the present invention, the coating layer A contains 1 to 50% by weight, preferably 1 to 50% by weight of a siloxane copolymerized acrylic resin.
-30% by weight.

The siloxane copolymer acrylic resin is a copolymer in which a siloxane component and an acrylic resin component are bonded to each other, and is a copolymer including, for example, a graft type and a block type. For example, by adding a radical initiator to both ends of an acrylic resin to polymerize siloxane, attaching a hydroxyl group to a side chain of the siloxane, and reacting with an acrylic having an isocyanate group or a carboxyl group at a terminal to form a comb polymer. Can be manufactured.

As the acrylic resin component used for the polymerization,
The same resins as those exemplified for the acrylic resin used as the binder resin of the coating layer A can be exemplified.

As the siloxane, the following structural formula is used as a chain component.

[0041]

Embedded image

R ₁ : CH ₃ , C ₆ H ₅ or H R ₂ : CH ₃ , C ₆ H ₅ , H or a functional group (for example,
(Epoxy group, amino group, hydroxyl group) n: 100 to 7000, and those having an epoxy group, amino group, hydroxyl group or other functional terminal group at the terminal. The siloxane compound need not necessarily be a homopolymer, but may be a copolymer or a mixture of several homopolymers.

The weight ratio of the acrylic resin component to the siloxane component is 98: 2 to 50:50, preferably 95: 5 to 60:40. The content of the siloxane copolymerized acrylic resin in the coating layer A is 1 to 50% by weight, preferably 1 to 30% by weight, and more preferably 1 to 20% by weight.
It is. When the amount is less than 1% by weight, the effect is insufficient and blocking occurs and an increase in charging is caused. On the other hand, when the amount exceeds 50% by weight, the adhesion of the magnetic layer or the back coat layer is deteriorated, or When the film is wound, transfer to the contact surface occurs, and when the film runs, the contact roll is stained.

In the present invention, the surfactant used for forming the coating layer A is not particularly limited, but examples thereof include a nonionic surfactant, an anionic surfactant, and a cationic surfactant. Among these nonionic surfactants,
In particular, those obtained by adding and bonding (poly) ethylene oxide to alkyl alcohol, alkylphenyl alcohol, higher fatty acid and the like are preferable.

As surfactants, polyoxyethylene alkyl phenyl ether compounds such as “Nonion NS-230” and “Non-Non NS
S-240 ”,“ HS-220 ”,“ HS-24 ”
0 ", a product name of Sanyo Chemical Co., Ltd.," Nonipol 20
0 "," Nonipol 400 "," Nonipol 500 ",
"Octapol 400"; trade name, manufactured by NOF Corporation, "Nonion E-230", "K-220", "K-230" as a polyoxyethylene alkyl ether-based compound; Examples of the ethylene ester compound include “Nonion S-15.4” and “S-40” manufactured by NOF Corporation.

The amount of the surfactant is from 5 to 50 per coating layer A.
% By weight, more preferably 5 to 40% by weight, particularly preferably 10 to 40% by weight, particularly preferably 12 to 30% by weight. When the amount of the surfactant is less than 5% by weight, the generation of coarse projections that may cause dropout cannot be suppressed. On the other hand, when the amount exceeds 50% by weight (per total solid content), streaks due to foaming occur. Coating defects occur.

Preferably, in order to improve the blocking resistance, the softening point (measured by drying a surfactant) measured in accordance with JIS K-7206 is 30 ° C.
It is preferable that it is above. However, when applying the coating liquid, in order to reduce the surface tension of the coating liquid so as not to cause coating omission, a surfactant other than the above should be used in combination within a range not exceeding 10% by weight (per total solid content). You may.

In the coating layer A in the present invention, other components besides the binder resin, the inert particles, the surfactant and the siloxane copolymerized acrylic resin may be added to the extent not affecting the present invention. Absent. In order to increase the slipperiness, a method of further adding a cellulosic resin is used. The layer thickness of the coating layer A is preferably 1 to 100 nm, more preferably 2 to 20 nm.

In the present invention, a film comprising a binder resin, inert particles (inactive particles B) and a surfactant is provided on the other surface of the base film on which the film layer A is formed (the surface on the nonmagnetic layer side). Preferably, layer B is provided. As the kind of the inert particles B contained in the coating layer B, the same particles as the inert particles A contained in the coating layer A can be exemplified, and the same particles or different particles may be used. The content of the inert particles B is preferably 1 to 20% by weight based on the weight of the coating layer B. The layer thickness of the coating layer B is preferably from 1 to 100 nm, more preferably from 2 to 20 nm.

The inert particles B have an average particle size of 5 to 100.
nm, preferably 10 to 50 nm. Further, those having a uniform particle size distribution are preferred. If the average particle size is less than 5 nm, the slipperiness and the abrasion resistance deteriorate. On the other hand, if the average particle size exceeds 100 nm, the particles will fall off and the abrasion resistance will deteriorate. Further, the spacing with the magnetic head becomes large, and it becomes difficult to provide the composite polyester film of the present invention as a base film of a high-density magnetic recording medium.

The inert particles B are preferably contained in the coating layer B such that the frequency of surface protrusions of the coating layer B is 1 × 10 ⁶ to 1 × 10 ⁸ particles / mm ² . If the frequency of the surface protrusions is less than 1 × 10 ⁶ / mm ² , the running durability of the magnetic recording medium is insufficient. On the other hand, when it exceeds 1 × 10 ⁸ / mm ² , the electromagnetic conversion characteristics are adversely affected.
A more preferred surface projection frequency is 2 × 10 ^{6 to} 5 × 10 ^7.
Pieces / mm ² , particularly preferably 3.0 × 10 ^{6 to} 3.0 ×
It is 10 ⁷ pieces / mm ² . The aggregation rate of the inert particles B in the coating layer B is preferably 20% or less. If the agglomeration rate exceeds 20%, particles may be easily scraped off, or the electromagnetic conversion characteristics of a magnetic recording medium may be adversely affected.

Ra ^B on the surface on which the coating layer B was formed was 0.5.
It is 1-2 nm, more preferably 0.5-1.5 nm. When Ra ^B exceeds 2 nm, the electromagnetic conversion characteristics deteriorate particularly when a metal thin film type magnetic recording medium is used. On the other hand, when Ra ^B is less than 0.1 nm, the slipperiness of the magnetic layer is extremely deteriorated and the running durability is insufficient, or the tape sticks to the magnetic head and causes tape squealing, so that it can be put to practical use. It is easy to disappear.

Examples of the binder resin constituting the coating layer B include the same resins as the binder resins constituting the coating layer A. Among them, water-soluble or water-dispersible acrylic resins, polyester resins and acryl-polyester resins Such resins are preferred from the viewpoints of adhesion to a polyester film (base film), projection retention, and slipperiness. The binder resin forming the coating layer B may be the same as or different from the binder resin forming the coating layer A. The content of the binder resin is preferably 20 to 90% by weight based on the weight of the coating layer B.

The surfactant constituting the coating layer B is not particularly limited, and examples thereof include a nonionic surfactant, an anionic surfactant, and a cationic surfactant. The same or different surfactant as the coating layer A may be used. The content of the surfactant is preferably 5 to 40% by weight based on the weight of the coating layer B.

In the present invention, it is preferable that the coating layer B further contains a siloxane copolymerized acrylic resin.

The siloxane copolymerized acrylic resin may be the same as the siloxane copolymerized acrylic resin exemplified as the one contained in the coating layer A. The content of the siloxane copolymerized acrylic resin in the coating layer B is 1 to 30% by weight,
Preferably it is 1 to 20% by weight. This amount is 30% by weight
If it exceeds, the adhesiveness of the magnetic layer when a magnetic recording medium is used is hindered. The siloxane copolymer acrylic resin contained in the coating layer B may be the same as or different from the siloxane copolymer acrylic resin contained in the coating layer A.

In the present invention, the other surface of the base film on which the coating layer A is formed (the surface on the magnetic layer side) is
It is preferable to provide a coating layer B ′ made of a binder resin, inert particles (inactive particles B ′), and a surfactant. Examples of the type of the inert particles B ′ contained in the coating layer B ′ include the same particles as the inert particles A contained in the coating layer A, and the same particles or different particles may be used.
The average particle size of the inert particles B ′ is 10 to 100 nm, preferably 20 to 80 nm, more preferably 20 to 60 nm.
It is. The content of the inert particles B ′ is 0.5 to 30% by weight, more preferably 1 to 20% by weight, based on the weight of the coating layer B ′.
Particularly, 2 to 10% by weight is preferable. Regarding the binder resin and the surfactant, the description of the binder resin and the surfactant in the coating layer B is directly used. The layer thickness of the coating layer B 'is preferably 1 to 100 nm, more preferably 2 to 20 nm.

The center line average roughness Ra ^B of the outer layer surface on which the coating layer B ′ is formed is 1 to 30 nm when the coating layer A forms the surface on the magnetic layer side, and more preferably 2 to 20 nm. Is preferred. When the Ra ^B is less than 1 nm, the winding property of the film and the transport property in the film forming process are insufficient, and blocking tends to occur. On the other hand, when Ra ^B exceeds 30 nm, there is a problem that the coating layer B ′ is easily scraped or the shape is transferred to the other surface when wound into a roll. This roughness may be provided by the coating layer B ′,
Further, it may be provided by a polyester film, or may be provided by a cooperative effect of the coating layer B ′ and the polyester film.

The composite polyester film of the present invention is obtained by replacing the film layer B 'on the surface of the polyester film (base film) opposite to the surface on which the film layer A is formed.
A coating layer C made of polyester containing inert particles (inactive particles C) may be formed. This coating layer C
Are laminated on the surface of the base film by a co-extrusion method. This coating layer C has the following formula

[0060]

0.1 ≦ (dc) ³ × Cc × tc ≦ 100 where dc (μm) is the average particle size of the inert particles in the layer C, and Cc (% by weight) is the inert particles. , And tc (nm) is the thickness of the layer C.

The average particle diameter dc of the inert particles C is 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. In addition, this average particle diameter dc
The content of the inert particles C having
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 particles C having the average particle diameter dc include (1) heat-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 (for example, aluminum sesquioxide, titanium dioxide, silicon dioxide, magnesium oxide, zinc oxide, zirconium oxide, etc.), (3) metal carbonate ( (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 diamond Kaolin is preferred, with crosslinked silicone resin particles, crosslinked polystyrene resin particles, alumina, titanium dioxide, silicon dioxide and calcium carbonate being particularly preferred.

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 dc of the inert particles C, for example, colloidal silica, α , Γ, δ, θ and the like can be preferably used. Further, among the particle types exemplified as the inert particles C having the average particle diameter dc, 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, even 10-300 nm, especially 30-250 nm
And the average particle diameter dc is preferably at least 50 nm, more preferably at least 100 nm, especially at least 150 nm. The content of the second and third particles (fine particles) is 0.005 to 1% by weight, more preferably 0.01 to 0.7% by weight, particularly 0.05 to 0.5% by weight based on the coating layer C. % By weight.

The center line average roughness Ra ^C of the outer layer surface on which the coating layer C is formed is preferably 1 to 30 nm, more preferably 2 to 20 nm when the coating layer A forms the surface on the magnetic layer side. preferable. If the Ra ^C is less than 1 nm, the winding property of the film and the transportability in the film forming process become insufficient, and blocking tends to occur. On the other hand, when Ra ^C exceeds 30 nm, there is a problem that when the film is wound into a roll, the shape is transferred to the other surface.

The composite polyester film in the present invention has an air bleeding index (“air leak index” measured by a Beck smoothness tester, manufactured by Toyo Seiki KK) of 1 to 15 m.
/ Hr is preferable. By exhibiting an air bleeding index in this range, the film can be improved in handling properties and winding properties without impairing the electromagnetic conversion characteristics.

In the present invention, the total thickness of the composite polyester film is usually from 2.5 to 20 μm, preferably 3.0.
10 μm, more preferably 4.0 to 10 μm. The layer thickness of the coating layer C is 1/1 of the total thickness of the composite film.
It is preferably at most 2, more preferably at most 1/3, particularly preferably at most 1/4. The thickness of the coating layers B and B ′ is 1 to 10
It is preferably 0 nm, more preferably 2 to 50 nm, especially 3 to 10 nm, especially preferably 3 to 8 nm.

The composite polyester film in the present invention can be obtained according to a conventionally known method or a method accumulated in the art. Among them, the laminated structure of the base film and the coating layer C is preferably manufactured by a co-extrusion method. Further, the lamination of the coating layers A, B and B ′ is preferably performed by a coating method.

For example, in the case of a biaxially oriented polyester film, before the extrusion die, the polyester A containing the above-mentioned inert particles P finely dispersed and contained therein is subjected to high-precision filtration, and then the melting point Tm ° C. to (Tm + 70) from the die. After co-extruding into a film at a temperature of 40 ° C., the mixture is rapidly cooled and solidified at 40 to 90 ° C. with a cooling roll to obtain an unstretched film. Thereafter, the unstretched film is uniaxially (longitudinal or transverse) at a temperature of (Tg−10) to (Tg + 70) ° C. (where Tg: glass transition temperature of polyester) according to a conventional method.
The film is stretched at a magnification of up to 8.0 times, preferably at a magnification of 3.0 to 7.5 times, and then Tg- (T
g + 70) at a temperature of <RTIgt;
Preferably, it is stretched at a magnification of 3.0 to 7.5 times. Further, if necessary, the film may be stretched again in the machine direction and / or the cross direction. That is, stretching in two, three, four, or multiple stages may be performed. The total stretching ratio is usually 9 times or more, preferably 12 to 35 times, and more preferably 15 to 32 times, as the area stretching 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., so that excellent dimensional stability is imparted. The heat setting time is preferably 1 to 60 seconds.

In the case of producing a composite film including the coating layer C, instead of producing the unstretched film,
Inside the extrusion die or before the die (generally, the former is called a multi-manifold type and the latter is called a feed block type)
Then, the above-mentioned polyester A in which the inert particles P are finely dispersed and contained, and the polyester C in which the inert particles C are finely dispersed and contained are each subjected to high-precision filtration, and then laminated and composited in a molten state. After forming a laminated structure with a suitable thickness ratio, and then coextruding from a die into a film at a temperature of melting point Tm ° C. to (Tm + 70) ° C., the mixture is rapidly cooled and solidified with a cooling roll at 40 to 90 ° C. to obtain an unstretched laminated film. Use the method of obtaining.

In the above method, the above-mentioned inert particles,
A coating liquid containing a binder resin, a surfactant, and a siloxane copolymerized acrylic, preferably an aqueous coating liquid, is applied. The coating is preferably performed on the surface of the polyester film 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 same applies to the coating layers B and C. The application method is not particularly limited,
For example, a roll coating method, a die coating method and the like can be mentioned.

The solid content of the above coating liquid, especially the aqueous coating liquid,
0.2 to 8% by weight, more preferably 0.3 to 6% by weight, in particular 0.
It is preferably 5 to 4% by weight. The coating liquid (preferably an aqueous coating liquid) contains other components, for example, other surfactants, stabilizers, dispersants, UV absorbers, thickeners, and the like, as long as the effects of the present invention are not impaired. Can be added.

The above-mentioned co-extrusion method is suitable when both the base film and the coating layer C are made of polyethylene-2,6-naphthalenedicarboxylate or polyethylene terephthalate, but only the base film is made of polyethylene-2,6 -The same applies to naphthalene dicarboxylate or polyethylene terephthalate.

In the production of the composite polyester film, additives other than the above-mentioned inert particles, for example, a stabilizer, a colorant, a specific resistance modifier for the molten polymer, and the like can be added to the polyester, if desired. .

In the present invention, in order to improve various functions 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 composite polyester film is changed in the longitudinal and transverse directions. 45 each
0 kg / mm ² or more and 600 kg / mm ² or more, furthermore, 480 kg / mm ² or more and 680 kg / mm
² or more, especially 550 kg / mm ² or more and 800 kg
/ Mm ² or more, especially 550 kg / mm ² or more and 1,
It is preferably at least 000 kg / mm ² . The crystallinity of the polyethylene terephthalate layer is 30 to 50.
%, And the crystallinity of the polyethylene-2,6-naphthalenedicarboxylate layer is desirably 28 to 38%. If any of them is below the lower limit, the heat shrinkage increases, while if it exceeds the upper limit, the abrasion resistance of the film deteriorates, and white powder is liable to be generated when the film slides on the roll or guide pin surface.

According to the present invention, a magnetic recording medium comprising the composite polyester film of the present invention as a base film, that is, a composite polyester film of the present invention and a magnetic layer present on the coating layer A or B of the composite film. A magnetic recording medium is also provided.

An embodiment for producing a magnetic recording medium from the composite polyester film of the present invention is as follows. The composite polyester film of the present invention is formed on the surface of the coating layer A or B having a center line average surface roughness of 0.1 to 2 nm by a method such as vacuum deposition, sputtering, or ion plating. A ferromagnetic metal thin film layer composed of an alloy or an oxide containing as a main component, a protective layer such as diamond-like carbon (DLC), if necessary, a fluorine-containing carboxylic acid-based lubrication The layers are provided sequentially. If necessary, the other surface, for example, the center line average roughness may be 1 to 3
By providing a well-known back coat layer on the surface of 0 nm, the deposition type magnet for high-density recording is particularly excellent in output in the short wavelength region, excellent in electromagnetic conversion characteristics such as S / N, C / N, etc., and with little dropout and error rate. It can be a recording medium.
This vapor deposition type electromagnetic recording medium is used for recording Hi for analog signals.
8. Very useful as a digital video cassette recorder (DVC) for recording digital signals, 8 mm data, and a tape medium for DDSIV.

The composite polyester film of the present invention is also characterized in that the surface of the coating layer A or B having a center line average surface roughness of 0.1 to 2 nm is coated with iron or an acicular fine magnetic powder (metal) containing iron as a main component. Powder), PVC, PVC
Evenly dispersed in a binder such as vinyl acetate copolymer,
The coating is performed so that the thickness of the magnetic layer is 1 μm or less, preferably 0.1 to 1 μm. Further, if necessary, a back coat layer may be provided on another surface, for example, a surface having a center line average roughness of 1 to 30 nm by a known method, so that output in a short wavelength region, S / N, C / N, etc. A metal-coated magnetic recording medium for high-density recording with excellent conversion characteristics and low dropout and error rate can be obtained. If necessary, a non-magnetic layer containing fine titanium oxide particles or the like is dispersed and coated on the coating layer A or B 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 includes Hi8 for analog signal recording, β cam SP, W-VHS, digital video cassette recorder (DVC) for digital signal recording, 8 mm data, DDSIV, digital β
It is extremely useful as a magnetic tape medium for cams, D2, D3, SX and the like.

The composite polyester film of the present invention is also provided with a fine acicular magnetic powder such as iron oxide or chromium oxide, or barium on the surface of the coating layer A or B having a center line average surface roughness of 0.1 to 2 nm. The plate-shaped fine magnetic powder such as ferrite is uniformly dispersed in a binder such as polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, and the thickness of the magnetic layer is 1μ.
m, preferably 0.1 to 1 μm. Further, if necessary, a back coat layer may be provided on another surface, for example, a surface having a center line average roughness of 1 to 30 nm by a known method, so that output in a short wavelength region, S / N,
An oxide-coated magnetic recording medium for high-density recording with excellent electromagnetic conversion characteristics such as C / N and 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 coating layer A or B in the same organic binder as the magnetic layer as an underlayer of the magnetic layer containing the magnetic powder. You can also. This oxide-coated magnetic recording medium is useful as a high-density oxide-coated magnetic recording medium such as a data streamer QIC for analog signal recording.

The W-VHS is an analog HDTV signal recording VTR, and the DVC is a digital HTV.
The film of the present invention is applicable to DTV signal recording, and can be said to be a very useful base film for these HDTV-compatible VTR magnetic recording media.

[0080]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. In the Examples and Comparative Examples, “parts” and “%” are based on weight unless otherwise specified, and the physical property values and properties in the present invention are measured and defined by the following methods, respectively, and are defined. is there.

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

(2) Average particle diameter I of particles (average particle diameter: 0.1
06μm or more) Product name “CP-50 Type Centrifugal Particle Size Analyzer (C
entrifugal particle 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
Year, see pages 242-247).

(3) Average particle size II of particles (average particle size:
(Less than 0.06 μm) 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 Instrument Inc.
nts Inc. NICOMP MODEL made by)
270 SUBMICRON PARTICLE SI
Expressed as the "equivalent spherical diameter" of the particle at the point of 50% by weight of the total particle as determined by ZER.

(4) Surface Roughness of Film and Coating Layer (Center Line Average Roughness: Ra) The center line average roughness (Ra) is measured according to JIS-B601. In the present invention, it is measured and measured under the following conditions using a stylus type surface roughness meter (SURFCORDER SE, 30C) manufactured by Kosaka Laboratory Co., Ltd. (A) Probe tip radius: 2 μm (b) Measurement pressure: 30 mg (c) Cut-off: 0.08 mm (d) Measurement length: 8.0 mm (e) How to summarize data: Repeatedly measure the same sample six times The center line average roughness (Ra) is determined as an average using the remaining five data except for the largest value.

(5) Number of Particle Protrusions (Density) Using SEM (scanning electron microscope, JEOL T-300 type), the surface of the composite film was magnified 30,000 times at an angle of 0 °.
, And the number of granular protrusions on the surface of the coating layer is counted, and the average value is calculated as the number of protrusions per piece / mm ² by area conversion.

(6) Aggregation rate of particles From the 20 photographs taken in (5) above, the number of two or more aggregates was counted, and the number of aggregates / the number of granular projections × 1
Calculated as 00 (%).

(7) Layer Thickness The total thickness of the film is randomly determined by a micrometer.
Measure the points and use the average value. The layer thickness is obtained by measuring the layer thickness on the thinner side by the method described below, and subtracting the layer thickness on the thicker side from the layer thickness on the thinner side than the total thickness. That is, using a secondary ion mass spectrometer (SIMS), the concentration ratio (M ⁺ /) of the element resulting from the highest concentration of the particles in the film having a depth of 5000 nm from the surface layer to the carbon element of the polyester. C ⁺ ) is defined as the particle concentration and the depth from the surface is 500
Analysis in the thickness direction is performed up to 0 nm. In the surface layer, the particle concentration is naturally low, and the particle concentration increases as the distance from the surface increases. In the case of the present invention, there are cases where the particle concentration once reaches a stable value 1 and then increases or decreases to a stable value 2 and cases where the particle concentration monotonously decreases. Based on this distribution curve, the former has a depth giving a particle concentration of (stable value 1 + stable value 2) / 2, and the latter has a depth at which the particle concentration becomes 1/2 of the stable value 1. (This depth is deeper than the depth that gives a stable value of 1), which is the layer thickness of the layer.

Secondary ion mass spectrometer (SIMS): P
The measurement conditions of 6300 manufactured by ERKIN ELMER are as follows. Primary ion species: O2 + Primary ion acceleration voltage: 12 KV Primary ion current: 200 mA Raster region: 400 μm □ Analysis region: Gate 30% Measurement vacuum degree: 6.0 × 10 ⁻⁹ Torr E-GUNN: 0.5 KV-3.0 A

When the particles most contained in the range of 5000 nm from the surface layer are organic polymer particles other than silicone resin, it is difficult to measure by SIMS. Therefore, FT-IR (Fourier transform infrared spectroscopy) is performed while etching from the surface. Method), and depending on the particles, a concentration distribution curve similar to the above is measured by XPS (X-ray high electron spectroscopy) or the like, and the layer thickness is determined.

The above is an effective measuring method for the co-extruded layer. In the case of the coated layer, a small piece of the film is fixedly formed with an epoxy resin, and an ultra-thin section (thickness of the film) of about 60 nm thickness is formed with a microtome. The sample is cut parallel to the flow direction), and this sample is taken with a transmission electron microscope (H-8, manufactured by Hitachi, Ltd.).
(Type 00), and the layer thickness is determined from the boundary surface of the layers.

(8) Chargeability Composite polyester film (500 mm width × 3000 m)
Length) at 150 ° C. in an atmosphere of 75% RH at 23 ° C.
The roll is rewound at a speed of / min, and the amount of peeling charge of the roll is measured using a digital test electricity meter Model-203 manufactured by Hugle Electronics Co., Ltd. ：: less than 2.5 kv Δ: 2.5 to less than 5.0 kv ×: 5.0 kv or more

(9) Number of coarse protrusions Non-contact three-dimensional roughness meter manufactured by WYKO Co., Ltd.
Using OPO-3D, measurement magnification 40 times, measurement area 2
The measurement is performed under the conditions of 42 μm × 239 μm (0.058 mm ² ) to obtain a surface roughness profile (original data). Of this profile, 15 continuous divisions (for example, j = 1 to 15) in the measurement direction and 15 continuous divisions (for example, in the orthogonal direction) perpendicular to the measurement direction (for example, j = 1 to 15).
k = 1 to 15), the average value of the heights in the area formed (15 × 15 divided areas) is calculated, and (j, k) =
The average height is (1, 1). Next, when one of the division positions in the measurement direction or the orthogonal direction is moved (for example,
j = 2-16, k = 1-15, or j = 1-15, k =
2-16) The average height of the 15 × 15 divided areas is determined, and the average height is set to (j, k) = (2, 1) or (1, 2). Furthermore, by moving the division position one by one,
For example, 15 × 1 of j = p to p + 14 and k = q to q + 14
The average value of the heights in the area of the five divisions is calculated, and (j,
k) = Average height of (p, q) is obtained, and calculation of the average height is repeated up to 256 divisions in the measurement direction and 256 divisions in the orthogonal direction. The surface roughness profile constituted by these average heights corresponds to the undulation 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 by a built-in roughness meter software, and protrusions having a height of 4 nm or more are counted as coarse protrusions. 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 manufactured by Toyo Baldwin Co., Ltd., trade name “Tensilon”, in a room adjusted to a temperature of 20 ° C. and a humidity of 50%, a length of 300 mm and a width of 12.7.
mm of the sample film is pulled at a strain rate of 10% / min, and is calculated by the following equation using the first straight line portion of the tensile stress-strain curve.

[0095]

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) Manufactured by Air Removal Using a Beck smoothness tester manufactured by Toyo Seiki Co., Ltd., 40 films were first superimposed, and the remaining 39 films were removed except for the one at the top of the sample table. Drill a hole with a diameter of 5 mm on the sheet and set it on the sample stage. At this time, the center of the hole is set at the center of the sample stage. In this state, 0.5kg
/ Cm 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 during 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 /
hr) is the air leak index G.

(12) Blocking property The processed surface of the two films and the surface to be processed were overlapped, and a pressure of 150 kg / cm ² was applied to the film at 60 ° C. at 80% R
The film is peeled after 65 hours in an atmosphere of H, and evaluated by its peeling force (g per 5 cm). The evaluation is performed based on the following criteria based on the peeling force. ：: 0 to less than 10 g / cm Δ: 10 g / cm or less to less than 15 g / cm ×: 15 g / cm or more to tear

(13) Blocking peeling force: 100 mm in the longitudinal direction of the roll-shaped film and 2 mm in the width direction.
The sample is sampled into a rectangle of 00 mm, and the base layer is subjected to corona treatment in an environment at room temperature of 25 ± 5 ° C. and humidity of 50 ± 5%. Processing is made by Kasuga Electric Co., Ltd., trade name "CG-10"
Processing is performed under the following conditions using a 2 ”type high frequency power supply. Current: 4.5 A Distance between electrodes: 1.0 mm Processing time: Processing is performed by passing between electrodes at a speed of 1.2 m / min. Immediately after the treated film is brought into contact with the base layer on the side opposite to the base layer and subjected to etching at a pressure of 100 kg / cm ² at room temperature of 60 ° C. and humidity of 80% for 17 hours, a tensile tester (“Tensilon”) To determine the peeling force per 100 mm width.

(14) Surface tension Evaluated according to the evaluation method of JIS K-6768.

(15) Abrasion resistance The film was sampled at a length of 25 to 30 cm and a width of 1/2 inch, and a leather blade was applied at an angle of 90 ° to the surface of the coating layer and a depth of 0.5 mm. Load 500g /
The width in the depth direction of the shaving powder adhering to the leather when running at a speed of 0.5 cm and a speed of 6.7 cm / sec is determined by microphotographing (× 160). Judgment is made as follows based on the width of the shavings in the depth direction. The smaller the width of the shaving powder in the depth direction, the better the shaving resistance. ：: less than 3 nm △: 3 nm to less than 5 nm ×: 5 nm or more

(16) Production of Magnetic Tape and Evaluation of Characteristics The surface of the coating layer B of the composite film was applied to the surface of the composite film by a vacuum evaporation method.
A ferromagnetic thin film of 100% cobalt is formed in two layers (each layer thickness is about 0.1 μm) so as to have a thickness of 0.02 μm, and a diamond-like carbon (DLC) film and a fluorine-containing carboxylic acid-based lubricating layer are formed on the surface. A backcoat layer having the following composition is applied to the surface of the coating layer A and dried to form a coating. The thickness of the back coat layer after drying is 0.8 μm.

Backcoat layer composition: carbon black 100 parts thermoplastic polyurethane 60 parts isocyanate compound (18 parts of Japan Polyurethane Industry Co., Ltd. Coronate L) silicone oil 0.5 parts methyl ethyl ketone 250 parts Then slit into 8 mm width, commercially available Load onto 8mm video cassette. Next, the properties of the tape are measured using the following commercially available equipment.

Equipment used: 8 mm video tape recorder: EDV manufactured by Sony Corporation
-6000 C / N measurement: Noise meter manufactured by Shibasoku Co., Ltd. C / N measurement A signal with a recording wavelength of 0.5 μm (frequency: about 7.4 MHz) is recorded, and the reproduction signal of 6.4 MHz and 7.4 MHz is measured. The ratio is expressed as a relative value, where the C / N of the tape is O / dB, and the C / N of a commercially available 8 mm video-evaporated tape is OdB. ：: 0 dB or more Δ: -3 to less than 0 dB ×: less than -3 dB

Running Durability C / N was measured after recording and reproducing 500 times at 40 ° C., 80% RH and a tape at a running speed of 85 cm / min.
The deviation from the initial value is determined based on the standard. ：: +0.0 dB or more with respect to the initial value Δ: -1.0 dB to less than +0.0 dB with respect to the initial value ×: less than -1.0 dB with respect to the initial value

Adhesion of magnetic layer A scotch tape No. 600 (manufactured by 3M) was attached to the surface of the magnetic layer cross-cut by 2 mm square so as to prevent air bubbles from entering. 2701 (1975) Hand-operated load roll, T-peeled at a head speed of 100 mm / min using Tensilon UM-11 manufactured by Toyo Boardwin Co., Ltd. Number of magnetic layers / total number of cross-cut magnetic layers ×
It is determined by 100 (%). ：: less than 0 to 3% Δ: less than 3 to 10 ×: 10% or more

Adhesiveness of back coat layer Scotch tape No. 600 (manufactured by 3M)
A width of 19.4 mm and a length of 8 cm are adhered so that air bubbles do not enter. This sample was T-peeled at a head speed of 300 mm / min using Tensilon UM-11 manufactured by Toyo Board Win Co., Ltd., between 5 cm of the sticking and laminating section with a manual load roll described in C2701 (1975). Is divided by the tape width to obtain g / cm. In the T-peeling, the laminated body is taken up with the tape side down, and the space between the chucks is set to 5 cm.

The evaluation is performed based on the following criteria based on the peel strength. ：: 50 g / cm or more Δ: 20 g / cm or less to less than 50 g / cm ² ×: less than 20 g / cm

(17) AFM Surface Roughness Digital Instrument Co., Ltd.
l Instruments Inc. ) Atomic force microscope, trade name "Nano Scope III AF"
Calculated under the following conditions using a scanner of "M" 2
The root mean square roughness is measured under the following conditions. Deep needle: single bond silicon sensor Scanning mode: tapping mode Scanning range: 10 μm × 10 μm Pixels: 256 × 256 data points Scanning speed: 2.0 Hz Measurement environment: room temperature, in air Numerical values are displayed as the average value measured five times .

Example 1 Dimethyl 2,6-naphthalenedicarboxylate and ethylene glycol, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, and phosphorous acid as a stabilizer were added in a conventional manner. To obtain polyethylene-2,6-naphthalate (PEN) containing substantially no inert particles.

The polyethylene-2,6-naphthalate was dried at 170 ° C. for 6 hours, supplied to an extruder, melted at a melting temperature of 310 ° C., extruded into a sheet from a die, quenched, and cooled to a thickness of 82 μm. An unstretched film was obtained.

The obtained unstretched film is preheated, further stretched 3.5 times in the machine direction at a film temperature of 95 ° C. between low-speed and high-speed rolls, quenched, and then coated on one side of the vertically-stretched film. The water-soluble coating liquid having the composition of the coating layer B shown in Table 1 was coated with the water-soluble coating liquid of the coating layer A on the other side at 0.009 μm and 0.09 μm, respectively.
It was applied to a thickness of 35 μm (after stretching and drying), was subsequently supplied to a stenter, and was stretched 5.6 times in the horizontal direction at 150 ° C. The obtained biaxially stretched film was heat-set with hot air at 200 ° C. for 4 seconds to obtain a biaxially oriented polyester film having a thickness of 4.9 μm.

Coating layer A ・ Binder resin Acrylic-modified polyester SH551A manufactured by Takamatsu Yushi Co., Ltd. 43.3 parts Methylcellulose SM15 manufactured by Shin-Etsu Chemical Co., Ltd. 21.7 parts ・ Siloxane copolymerized acrylic resin Shin-Etsu Chemical Co., Ltd. X -22-8053 5 parts ・ Inert particles Acrylic particles (average particle size: 40 nm) 10 parts ・ Surfactant Nonion NS-240 manufactured by Nippon Oil & Fat Co., Ltd. 20 parts Coating layer B ・ Binder resin Acrylic modified by Takamatsu Oil & Fat Co., Ltd. Polyester IN-170-6 70 parts ・ Inert particles 10 parts of cross-linked acrylic resin particles (average particle size 40 nm) ・ Surfactant Nonion NS-240 manufactured by NOF Corporation 20 parts

[Comparative Examples 1, 2, 7] Coating layer A and coating layer B
A polyester film was obtained in the same manner as in Example 1, except that the composition was changed as shown in Table 1.

Example 3 Polyethylene-2,6-naphthalate containing substantially no inert particles and polyethylene-2,6-naphthalate containing 0.2% by weight of silica particles having an average particle diameter of 200 nm were used. After drying at 170 ° C. for 6 hours each, the mixture was melted at 310 ° C. using two extruders, and the particles-free polyethylene-2,6-naphthalate: particles-containing polyethylene-2 were melted using a multi-manifold type coextrusion die. 6-naphthalate-2: 1, and the same procedure as in Example 1 was carried out except that the coating layer A shown in Table 1 was formed on the particle-containing layer side and the coating layer B was formed on the other surface.
A polyester film was obtained.

[Example 2, Comparative Examples 3 to 6] Dimethyl terephthalate and ethylene glycol, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, and phosphorous acid as a stabilizer were added in a conventional manner. Polymerization yielded polyethylene terephthalate (PET) substantially free of inert particles.

This polyethylene terephthalate was converted to 170
After drying at 3 ° C. for 3 hours, the mixture was fed to an extruder and melted at a temperature of 280
It was melted at 300 ° C., extruded into a sheet from a die, and quenched to obtain an unstretched film having a thickness of 82 μm.

The obtained unstretched film is preheated, further stretched 3.2 times in the machine direction at a film temperature of 95 ° C. between low-speed and high-speed rolls, quenched, and then coated on one side of the longitudinally stretched film. The water-soluble coating liquid having the composition of the coating layer B and the water-soluble coating liquid having the composition of the coating layer A on the other surface were respectively 0.009 μm and 0.09 μm.
It is applied so as to have a thickness of 35 μm (after stretching and drying), and then supplied to a stenter, and is then laterally 4.1 at 110 ° C.
It was stretched twice. The obtained biaxially oriented polyester film was heat-set with hot air at 220 ° C. for 4 seconds to obtain a biaxially oriented polyester film having a thickness of 6.0 μm. Examples 1 to 3,
Table 2 shows the film properties of Comparative Examples 1 to 7.

[0118]

[Table 1]

[0119]

[Table 2]

As is clear from Tables 1 and 2, the composite polyester film of the present invention has a small charge amount of the film, no blocking between the films, little shaving, electromagnetic conversion characteristics, adhesion of the magnetic layer, and back coat. Very good layer adhesion. On the other hand, those which do not satisfy the requirements of the present invention cannot simultaneously satisfy these characteristics.

The composite polyester film of the present invention has a total thickness of about 2.5 to 20 μm and is suitably used as a base for a magnetic recording medium. The magnetic recording medium is useful for a metal thin film type. Further, the composite polyester film of the present invention can be used not only for a coating type magnetic recording medium having a magnetic layer thickness of 1 μm or less, but also for a digital signal recording type magnetic recording medium.

Example 4 Dimethyl terephthalate and ethylene glycol, manganese acetate as a transesterification catalyst, trimellitic acid as a polymerization catalyst, phosphorous acid as a stabilizer, and spherical silica having an average particle diameter of 60 nm as a lubricant. Was added by 0.03% by weight and polymerized by a conventional method to obtain polyethylene terephthalate having an intrinsic viscosity of 0.60 (PET-A).

Further, in the same manner as described above, as a lubricant,
0.1% by weight of inert fine particles of spherical silicone having an average particle diameter of 0.6 μm and 0.2% by weight of inert fine particles of θ-type alumina having an average particle diameter of 0.06 μm are polymerized to give an intrinsic viscosity of 0%. .60 of polyethylene terephthalate (PE
TC).

Each of PET-A and PET-C was 170
After drying at 3 ° C. for 3 hours, the mixture was supplied to two extruders, melted at a melting temperature of 280 to 300 ° C., filtered with a high precision steel wire filter having an average opening of 11 μm, and then used with a multi-manifold type co-extrusion die. PET-A layer on one side
The -C layer was laminated and rapidly cooled to obtain an unstretched laminated film having a thickness of 89 µm.

The obtained unstretched laminated film was preheated, further stretched 3.3 times at a film temperature of 100 ° C. between low-speed and high-speed rolls, quenched, and then cooled to a P of the longitudinally stretched film.
An aqueous coating liquid having the following composition (total solid content concentration: 1.0%) was applied to the ET-A layer side by a kiss coat method. Binder: Acrylic-modified polyester (IN-170-6, manufactured by Takamatsu Yushi) 60% Inactive particles: Average particle size: 30 nm Acrylic filler (MA02W, manufactured by Nippon Shokubai) 5% Surfactant X: (Nonion NS-208, manufactured by Nippon Yushi)
5) 2% 〃 Y: (Nonion NS-240 manufactured by NOF) 23% Siloxane copolymerized acrylic: (X-22 manufactured by Shin-Etsu Chemical Co., Ltd.)
-8053) 10%

Subsequently, it was supplied to a stenter and 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 give a total thickness of 6.4 μm.
m, a biaxially oriented composite polyester film having a thickness of 1.0 μm for the base layer (PET-A layer) and 0.010 μm for the coating layer A was obtained. The thicknesses of the AET-A and PET-C layers were adjusted by the discharge rates of two extruders. The AFM surface roughness of the coating layer A of this film is 1.4 nm, R
a ^A is 1.8 nm, Ra ^C of PET-C layer 7.
5 nm, and the Young's modulus of the film is 500 in the vertical direction.
kg / mm ^2, was transverse 700 kg / mm ^2. Table 3 shows the surface characteristics of this composite polyester film and the characteristics of a ferromagnetic thin film-deposited magnetic tape using this film.

Comparative Example 8 The procedure was the same as that of Example 4 except that the applied aqueous coating liquid (total solid content concentration: 1.0%) was as follows. Binder: 70% acrylic-modified polyester (IN-170-6, manufactured by Takamatsu Yushi) Inactive particles: 5% acrylic filler (MA02W, manufactured by Nippon Shokubai) having an average particle size of 30% Surfactant X: (Nonion NS-208., Manufactured by Nippon Yushi)
5) 2% 〃 Y: (Nonion NS-240 manufactured by NOF) 23% Ra ^A of the coating layer A of the obtained composite film is 1.8 nm.
In and, Ra ^C of PET-C layer was 7.5 nm.
Table 3 shows other film characteristics and the characteristics of the ferromagnetic thin-layer evaporated magnetic tape using this film.

Comparative Example 9 The procedure of Example 4 was repeated except that the applied aqueous coating liquid (total solid concentration: 1.0%) was changed as follows. Binder: Acrylic-modified polyester (Takamatsu Yushi I
N-170-6) 15% Inactive particles: Acrylic filler having an average particle diameter of 30 nm (MA02W manufactured by Nippon Shokubai) 5% Surfactant X: (Nonion NS-208 manufactured by Nippon Yushi)
5) 1% Ｙ Y: (Nonion NS-240 manufactured by NOF Corporation) 19% Siloxane copolymerized acrylic: (X-22 manufactured by Shin-Etsu Chemical Co., Ltd.)
-8053) 60% Ra ^A of the coating layer A of the obtained composite film is 2.0 nm.
In and, Ra ^C of PET-C layer was 7.5 nm.
Table 3 shows the other properties and the properties of the ferromagnetic thin-layer evaporated magnetic tape using this film.

[0129]

[Table 3]

As is evident from Table 3, the composite polyester film of Example 4 has good anti-blocking peeling force and excellent electromagnetic conversion characteristics and running durability. On the other hand, the comparative film cannot satisfy these characteristics.

[0131]

According to the present invention, the charge amount of the film is small, there is no blocking between the films, there is little shaving, and the electromagnetic conversion characteristics, the adhesion of the magnetic layer, and the adhesion of the back coat layer are excellent. In particular, it is possible to provide a composite polyester film suitable for use as a substrate for a high-density magnetic recording medium.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 3/00 C08K 3/00 5/00 5/00 13/04 13/04 C08L 33/04 C08L 33 / 04 67/02 67/02 G11B 5/73 G11B 5/704 // B29K 33:04 67:00 105: 16 B29L 7:00 9:00

Claims (21)

[Claims] 1. A polyester film as a base film, wherein at least one side of the film has a binder resin,
A composite polyester film having a coating layer A composed of inert particles, a surfactant and a siloxane copolymerized acrylic resin, wherein the content of the siloxane copolymerized acrylic resin in the coating layer A is 1 to 50% by weight. Characteristic composite polyester film. 2. The surface tension of the outer surface of the coating layer A is 45 dy.
The composite polyester film according to claim 1, which is at least n / cm. 3. The binder resin forming the coating layer A,
2. The composite polyester film according to claim 1, which is at least one resin selected from the group consisting of a water-soluble or water-dispersible acrylic resin, a polyester resin, and an acrylic-polyester resin. 4. The composite polyester film according to claim 1, wherein the surfactant forming the coating layer A is a nonionic surfactant. 5. The center line average roughness Ra of the outer surface of the coating layer A.
The composite polyester film according to any one of claims 1 to 4, wherein ^A is 1 to 30 nm. 6. The method according to claim 1, wherein the inert particles contained in the coating layer A have an average particle size of 10 to 200 nm, and the content is 5 to 40% by weight (based on the coating layer A). Composite polyester film. 7. The polyester forming the base film is substantially free of inert particles or has an average particle size of 200.
The composite polyester film according to claim 1, further comprising 0 nm or less of inert particles. 8. A film layer B comprising a binder resin, inactive particles and a surfactant is formed on the surface of the polyester film opposite to the surface on which the film layer A is formed, and the average particle size of the inactive particles Is 5 to 100 nm, the aggregation rate is 20% or less, and the outer surface of the coating layer B has projections of 1 × 10 ⁶ to 1 × 10 ⁸ / mm ^{2 due} to the inert particles. And the center line average roughness Ra ^B of the surface of the coating layer ^B
Is from 0.1 to 2 nm. 9. The composite polyester film according to claim 8, wherein the coating layer B contains 1 to 30% by weight of a siloxane copolymerized acrylic resin. 10. The binder resin forming the coating layer B is at least one resin selected from the group consisting of water-soluble or water-dispersible acrylic resins, polyester resins and acrylic-polyester resins. 10. The composite polyester film according to 9. 11. The center line average roughness R of the outer surface of the coating layer A.
composite polyester film according to any one of claims 1 to 4 a ^A is 0.1 to 2 nm. 12. The inert particles contained in the coating layer A have an average particle size of 10 to 50 nm, and the content thereof is 0.5 to 3 nm.
The composite polyester film according to claim 1, which is 0% by weight (based on the coating layer A). 13. The outer surface of the coating layer A has 1 to 40 projections / μm ^{2 due} to inert particles contained in the coating layer A.
The composite polyester film according to claim 1, wherein the composite polyester film is present at a density of: 14. An outer surface of the coating layer A obtained from a surface roughness profile measured by a non-contact three-dimensional roughness meter,
14. The composite polyester film according to claim 1, wherein the density of the coarse protrusions having a height of 4 nm or more is 200 / mm ² or less. 15. The polyester forming the base film contains substantially no inert particles or has an average particle size of 40.
The composite polyester film according to claim 1, wherein the composite polyester film contains inert particles having a volume shape factor of 0.1 to π / 6 or less. 16. A film layer B ′ comprising a binder resin, inert particles and a surfactant is formed on the surface of the polyester film opposite to the surface on which the film layer A is formed,
The composite polyester film according to any one of claims 11 to 15, wherein the outer surface of the coating layer (B ') has a center line average roughness of 1 to 30 nm. 17. A film layer C made of polyester containing inert particles is formed on the surface of the polyester film opposite to the surface on which the film layer A is formed, and the film layer C is formed by co-extrusion. And the center line average roughness of the outer surface of the coating layer C is 1 to 30
The composite polyester film according to any one of claims 11 to 15, which has a thickness of nm. 18. The coating layer C has the following formula: 0.1 ≦ (dc) ³ × Cc × tc ≦ 100 where dc (μm) is the average particle size of the inert particles in the layer C. The composite polyester film according to claim 17, which satisfies that the content of the inert particles is represented by Cc (% by weight) and the thickness of the layer C is represented by tc (nm). 19. A magnetic recording medium comprising a composite polyester film according to claim 8 and a magnetic recording layer provided on the coating layer B. 20. A magnetic recording medium comprising a composite polyester film according to claim 11 and a magnetic recording layer provided on the coating layer A. 21. Hi8 for analog signal recording, digital video cassette recorder for digital signal recording or 8 mm data, for DDSIV.
0. The magnetic recording medium according to item 0.