JP2002011841A - Composite polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite polyester film which has no coating mottle and is excellent in handling properties and which is excellent in electromagnetic conversion characteristics, DO characteristics and running durability since it holds a sufficient heat resistance and retains surface flatness on the occasion of making it a magnetic tape, for instance. SOLUTION: This composite film is prepared by laminating a coat layer A containing an acrylic polyester resin on at least one surface of a polyester film. The acrylic polyester resin has a number-average molecular weight of 10,000-1,000,000 (1) and at least one or more tan δ peaks (2), the highest peak temperature (Tδ) at tan-δ being 60-110 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a composite polyester film. More specifically, a composite polyester film for magnetic recording media with excellent electromagnetic conversion characteristics and running durability,
In particular, it relates to a composite polyester film for a ferromagnetic metal thin film type magnetic recording medium for recording digital data for digital video cassette tapes, data storage and the like.

[0002]

2. Description of the Related Art A consumer digital video tape put into practical use in 1995 has a structure in which a metal magnetic thin film of Co is provided on a base film by vacuum evaporation, and the surface thereof is coated with a diamond-like carbon film.
Although the surface is flattened as compared with the ME (evaporation) tape for use, it has good durability. The base film comprises a polyester film, a polymer blend containing a water-soluble polyester copolymer adhered to at least one surface of the film, and a discontinuous film mainly composed of fine particles having a particle size of 5 to 50 nm. A composite polyester film having fine projections formed by fine particles on the surface of a continuous film (for example, JP-B-63-57238) is used. This base film is Hi8
This film has a smaller metal magnetic film-formed surface roughness than the ME base.

On the other hand, a number of proposals have also been made with respect to a water-soluble primer such as a water-soluble polyester copolymer used for the discontinuous film, for improving the surface of the polyester film, improving the adhesion, or preventing the filler from falling off due to scraping. (JP-A-54-43017, JP-B-49-10243, and JP-A-58-1).
24651, JP-A-63-37937, JP-A-1-165633, JP-A-3-17135, and the like.

[0004]

However, in recent years,
In order to increase the recording capacity, it is necessary to make the tape longer than ever, and for that purpose, it is necessary to make the base film thinner. Further, in order to increase the productivity of the vapor deposition tape, it is necessary to increase the vapor deposition speed. Usually, a method of cooling the base film by bringing the non-magnetic surface side of the base film into close contact with a cooling can is used for vapor deposition.However, as the base film becomes thinner and the vapor deposition speed increases, the heat applied to the base film during vapor deposition is increased. The load is getting higher and higher. In a conventional base film, oligomers are generated when exposed to heat,
There has been a problem that an error occurs or the base film is thermally deformed at the time of vapor deposition, and as a result, a vapor deposition layer formed thereon is roughened and electromagnetic conversion characteristics are deteriorated. As a method of preventing this problem, a method of flattening the surface of the non-magnetic surface of the base film in order to further adhere to the cooling can is also used. Had a problem that was significantly inferior. Also, even if the thermal deformation of the base film itself is no longer a problem due to process improvement, etc., the heat resistance of the primer layer applied for the purpose of improving the surface characteristics of the base film is not sufficient, and the conventional well-known technology is used. However, it was difficult to achieve both heat resistance and surface flatness required for this application.

It is an object of the present invention to prevent the generation of oligomers and the deformation of a coating layer (primer layer) in a vapor deposition step, and to provide a magnetic recording medium which is excellent in error and electromagnetic conversion characteristics of a magnetic tape obtained and has good handling properties. Another object of the present invention is to provide a composite polyester film which is particularly useful as a base film.

[0006]

The present invention has the following arrangement to solve the above-mentioned problem. A composite film obtained by laminating a coating layer A containing an acrylic-polyester resin on at least one surface of a polyester film,
The acrylic-polyester resin is (1) 10,000 or more and 10
It has a number average molecular weight of less than or equal to 100,000, (2) has at least one tan δ peak, and (3) has a maximum peak temperature (Tδ) of tan δ of 60 ° C. or more and 110 ° C. or less. Composite polyester film.

[0007]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, the polyester constituting the film may be any polyester which forms a high-strength film by molecular orientation. Among them, polyethylene terephthalate, polyethylene-2,6-
Naphthalenedicarboxylate is preferred. These include not only homopolymers, but also those in which at least 80% of their constituents are ethylene terephthalate or ethylene-2,6-naphthalenedicarboxylate. Examples of the polyester copolymer component other than ethylene terephthalate and ethylene-2,6-naphthalenedicarboxylate include, for example, diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylene glycol, and 1,4-cyclohexanedimethanol. Diol component, dicarboxylic acid component such as adipic acid, sebacic acid, phthalic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid; trifunctional or higher polycarboxylic acid component such as trimellitic acid and pyromellitic acid; p-oxyethoxy Benzoic acid and the like.
The polyester is further mixed with at least one of an alkali metal salt derivative of a sulfonic acid that is non-reactive with the polyester component and a polyalkylene glycol that is substantially insoluble in the polyester in a range not exceeding 5% by weight. Is also good.

[0008] The polyester contains substantially no inert particles or 0.5% by weight, if any, of inert particles.
The content is preferably not more than 0.3% by weight or less. As the inert particles, calcium carbonate, aluminum oxide, silicon oxide, inert inorganic particles represented by titanium oxide, or crosslinked silicone resin,
Heat-resistant organic particles represented by a cross-linked polystyrene resin and a cross-linked acrylic resin are exemplified. This content is 0.
If the content exceeds 5% by weight, the electromagnetic conversion characteristics of a magnetic tape deteriorate. When the particles contain inert particles, the average particle size is 30 to 500 nm, and more preferably 50 to 300 nm.
It is preferably nm.

The polyester film in the present invention may be a single-layer film or a multilayer film having two or more layers by a co-extrusion method or the like. In the case of a multilayer film, the polyester of the surface layer on the magnetic layer forming surface side substantially does not contain inert particles, or even if it contains, does not exceed 0.05% by weight, and more preferably exceeds 0.01% by weight. It is preferable that it is not in the range. 0.05% is applied to the polyester layer forming the opposite surface (nonmagnetic layer surface).
Preferably, it contains 0.5 to 0.5% by weight, more preferably 0.1 to 0.3% by weight of inert particles.

In the present invention, the coating layer A laminated on at least one side of the polyester film has (1) a number average molecular weight of 10,000 to 1,000,000 and (2) at least 1
It is necessary to include an acryl-polyester resin having two tan δ peaks and (3) having a maximum peak temperature (T δ) of tan δ of not less than 60 ° C and not more than 110 ° C.

The acryl-polyester resin is used to mean an acryl-modified polyester resin and a polyester-modified acryl resin. The acryl-polyester resin is composed of an acrylic resin component and a polyester resin component bonded to each other. Include type. Such an acrylic-polyester resin, for example, adds a radical initiator to both ends of the polyester to polymerize the acrylic monomer, or adds a radical initiator to the side chain of the polyester 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 the terminal.

[0012] The acrylic-polyester resin must have a number average molecular weight of 10,000 to 1,000,000, preferably 30,000 to 800,000, more preferably 50,000 to 500,000. If the molecular weight is less than 10,000, the strength and heat resistance of the film are insufficient, and poor film formation in the polyester film manufacturing process and poor heat resistance in the tape manufacturing process occur. On the other hand, if it exceeds 1,000,000, the adhesiveness to the polyester film is reduced, which impairs the coatability of the coating layer A and lowers the tape properties.

Here, the number average molecular weight is determined by so-called GPC (gel permeation chromatography) in terms of monodisperse polystyrene (standard molecular weight), and when having two or more molecular weight distributions, the larger one is used. It is determined from the molecular weight distribution.

The acrylic-polyester resin further has at least one or more tan δ peaks, and has a maximum peak temperature (T δ) of tan δ of 60 ° C. or more.
It must be below 0 ° C. This maximum peak temperature (T
δ) is preferably from 65 ° C to 105 ° C, more preferably from 70 ° C to 100 ° C. If the maximum peak temperature of tan δ is less than 60 ° C., poor heat resistance occurs in the tape manufacturing process, and the tape properties become insufficient. On the other hand, when the temperature exceeds 110 ° C., the surface after the film is formed becomes rough, and satisfactory tape properties cannot be obtained.

Here, tan δ is measured by using a dynamic viscoelasticity measuring device at a measurement frequency of 10 Hz and a dynamic displacement of ± 25 × 10
^-4 cm. When a plurality of tan δ peak temperatures are obtained, the highest peak temperature, that is, the highest temperature peak temperature is determined as Tδ.

The acrylic-polyester resin has a molar ratio of polyester resin component / acrylic resin component of 1/9.
It is preferably not less than 5/5 and more preferably not less than 2/8 and not more than 4/6. If this ratio is less than 1/9, the adhesion of the coating layer A to the polyester film will be insufficient.
When the ratio exceeds / 5, the abrasion resistance of the coating layer A and the effect of suppressing oligomers of the base film become inferior. That is, the adhesiveness between the coating layer A and the polyester film is ensured by the polyester resin component constituting the acrylic-polyester resin, and the abrasion resistance of the coating layer A and the oligomer suppressing effect of the base film are ensured by the acrylic resin component.

The polyester resin component constituting the acrylic-polyester resin comprises a polybasic acid component and a polyol component. Examples of the polybasic acid component include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride,
Preferred are 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, dimer acid, 5-sodium sulfoisophthalic acid and the like. These acid components are usually composed of two or more kinds, and may contain a small amount of an unsaturated polybasic acid component such as maleic acid, itaconic acid, or a hydroxycarboxylic acid component such as p-hydroxybenzoic acid. Examples of the polyol component include ethylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol,
Xylene glycol, dimethylolpropane, poly (ethylene oxide) glycol, poly (tetramethylene oxide) glycol and the like are preferably exemplified. These polyol components can be two or more kinds. Among them, the use of 1,4-cyclohexanedimethanol is particularly preferable in terms of achieving both surface flatness and heat resistance.

The polyester resin component can be produced by reacting the above-mentioned polybasic acid or its ester-forming derivative with the above-mentioned polyol or its ester-forming derivative by a conventional method.

The acrylic resin component constituting the acrylic-polyester resin comprises (A) an alkyl methacrylate (M _A ) of 50 mol% to 95 mol%, and (B) an epoxy group-containing acrylic monomer (M _B ) of 3 mol%. More than 35
Mol% or less, and (C) alkyl acrylate (M _C )
It is preferred that the main component be 3 mol% or more and 30 mol% or less. The proportion of component (A) is more preferably 6
0 mol% or more and 90 mol% or less. If this ratio is less than 50 mol%, polymerization of the acrylic-polyester resin becomes difficult. On the other hand, if it exceeds 96 mol%, the amounts of the components (B) and (C) decrease, and the abrasion and the surface flatness deteriorate. Examples of the alkyl group of the component (A) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group,
-Butyl, isobutyl, t-butyl, 2-ethylhexyl, cyclohexyl and the like.

The proportion of the (B) epoxy group-containing acrylic monomer is more preferably 7 mol% to 30 mol%.
It is as follows. If this ratio is less than 3 mol%, the crosslink density of the resin is reduced, the shaving property is deteriorated, and the resin is thermally deformed at the time of vapor deposition. As a result, the vapor deposited layer formed thereon is roughened, and the magnetic recording is performed. When used as a medium, the electromagnetic conversion characteristics deteriorate. On the other hand, if it exceeds 35 mol%, the background resin portion between the filler protrusions of the coating layer A becomes coarse and the electromagnetic conversion characteristics deteriorate when used as a magnetic recording medium. Preferred examples of the epoxy group-containing acrylic monomer include glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether.

The proportion of the alkyl acrylate (C) is preferably from 3 mol% to 30 mol%, more preferably from 4 mol% to 20 mol%. If this ratio is less than 3 mol%, the background resin portion between the filler protrusions of the coating layer A becomes coarse, and the electromagnetic conversion characteristics deteriorate when used as a magnetic recording medium. On the other hand, if the content exceeds 30 mol%, the abrasion property deteriorates and the material is thermally deformed at the time of vapor deposition. As a result, the vapor deposition layer formed thereon is roughened and the electromagnetic conversion characteristics are deteriorated when used as a magnetic recording medium. Would. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group,
-Butyl group, 2-ethylhexyl group, cyclohexyl group and the like are preferred.

It is preferable that the acrylic resin component further satisfies the following formulas (1) and (2).

[0023]

1 ≦ M _A / (M _B + M _C ) ≦ 10 (1) 0.1 ≦ M _B / M _C ≦ 20 (2) (where M _A is an alkyl methacrylate) the number of moles, M _B
Represents the number of moles of the epoxy group-containing acrylic monomer, and M _C represents the number of moles of the alkyl acrylate. If M _A / (M _B + M _C ) is less than 1, the heat resistance of the coating layer A is inferior and poor heat resistance occurs in the tape manufacturing process, which is not preferable. On the other hand, when it exceeds 10, the surface flatness is reduced and sufficient tape properties cannot be obtained. Also, MB /
When the MC is less than 0.1, the surface flatness is extremely lowered, which is not preferable. On the other hand, when the MC is more than 20, an acrylic polymer having a high degree of polymerization cannot be obtained. Lower, which is not preferred.

The coating layer A in the present invention preferably contains, in addition to the acrylic-polyester resin described above, inert particles having an average particle size of 5 nm to 50 nm, and a surfactant.

The acrylic-polyester resin coating layer A
The ratio in the medium is preferably from 40% by weight to 89% by weight, more preferably from 50% by weight to 75% by weight. When the proportion is less than 40% by weight, the adhesion to the polyester film is reduced, and the coating layer A is easily scraped. On the other hand, when the proportion exceeds 89% by weight, the amounts of the inert particles and the surfactant component are reduced. However, this may impair the tape properties and the coatability of the coating layer A. Further, in order to obtain sufficient magnetic tape properties, the first main component constituting the coating layer A is preferably an acrylic-polyester resin. It is preferable to contain more than each of the agents.

Examples of the material of the inert particles contained in the coating layer A include polystyrene, polystyrene-divinylbenzene, polymethyl methacrylate, methyl methacrylate copolymer, methyl methacrylate copolymer crosslinked product, polytetrafluoroethylene, and polyvinylidene fluoride. Any of organic materials such as ride, polyacrylonitrile, benzoguanamine, and silicone, and inorganic materials such as silica, alumina, titanium dioxide, kaolin, calcium carbonate, talc, and graphite may be used. Alternatively, core-shell type particles having a multilayer structure in which the inside and outside of the particles are made of substances having different properties may be used.

The inert particles preferably have a volume shape factor (f) defined by the following formula of 0.1 to π / 6, more preferably 0.4 to π / 6, substantially a sphere or rugby. Ball-shaped elliptical spheres are preferred. When the f is less than 0.1, for example, in the case of flaky particles, the electromagnetic conversion characteristics are likely to deteriorate when used as a magnetic recording medium.

[0028]

Equation 3] f = v / d ³ where, V is the volume of the inert particles, d represents the average particle size.

The inert particles have an average particle size of 5-5.
0 nm, more preferably 10 to 4 nm.
0 nm. If the particle size is less than 5 nm, the running durability with the head is insufficient when the magnetic recording medium is used, while if it exceeds 50 nm, the spacing with the head is large when the magnetic recording medium is used, Electromagnetic conversion characteristics decrease. The ratio of the inert particles in the coating layer A is 1% by weight.
It is preferably at least 20% by weight and more preferably at most 3% by weight and at most 10% by weight. This ratio is 1
When the amount is less than 20% by weight, the running durability of the magnetic recording medium with the head is insufficient. On the other hand, when the amount is more than 20% by weight, particles easily fall off from the coating layer A.

The height of the projections formed on the coating layer A with the inert particles as nuclei is preferably 5 to 50 nm, more preferably 10 to 40 nm. If the protrusion height is less than 5 nm, the running durability with the head is insufficient when the magnetic recording medium is used. On the other hand, if the protrusion height exceeds 50 nm, the spacing with the head is large when the magnetic recording medium is used. In addition, the electromagnetic conversion characteristics decrease. Further, the height / half width of the projection is preferably 0.3 or more and 0.8 or less, more preferably 0.4 or more and 0.7 or less. When the ratio is less than 0.3, the protrusions are easily shaved, while when the ratio is more than 0.8, the acrylic-polyester resin around the inert particles is deformed by heat at the time of deposition, and as a result, The formed vapor deposition layer is roughened, and the electromagnetic conversion characteristics are deteriorated when used as a magnetic recording medium.

As the surfactant in the coating layer A, any of an anionic type, a cationic type and a non-ionic type may be used, and among them, the non-ionic type is preferable. Examples of the nonionic surfactant include an ester type, an ether type, and an alkylphenol type. Specific examples of such surfactants include polyoxyethylene alkyl phenyl ether compounds, trade names of NON-NS-230, NS-240, and HS-
220, HS-240, Sanyo Kasei Co., Ltd., “Nonipol 200”, “Nonipol 40”
0 "," Nonipol 500 "," Octapol 40 "
"0"; trade name of polyoxyethylene alkyl ether compound manufactured by NOF Corporation, "Nonion E-23"
0, "K-220" and "K-230"; trade names of polyoxyethylene ester compounds of higher fatty acids manufactured by NOF Corporation, "Nonion S-15.4", "S-K-220" 40 "and the like.

The ratio of the surfactant in the coating layer A is 1
It is preferably from 0% by weight to 50% by weight, more preferably from 15% by weight to 40% by weight. If this ratio is less than 10% by weight, the coatability deteriorates and the running durability with the head becomes insufficient when used as a magnetic recording medium. On the other hand, if it exceeds 50% by weight, the heat resistance of the coating layer A decreases. Lower, which is not preferred.

If necessary, other components such as a stabilizer, a dispersant, a UV absorber, a thickener, and a release agent are added to the coating layer A as long as the effects of the present invention are not impaired. be able to.

The composite polyester film of the present invention has a surface opposite to the surface on which the coating layer A is formed (the other surface: surface B).
In addition, another coating layer for the purpose of imparting lubricity may be provided.

The surface roughness Ra of the other surface (B surface) is preferably from 2 nm to 10 nm, more preferably from 2 nm to 7 nm. This surface roughness R
When a is less than 2 nm, the handleability during the film forming process and the vapor deposition of the polyester film is extremely poor. On the other hand, if the surface roughness Ra exceeds 10 nm, the polyester film does not adhere sufficiently to the cooling can at the time of vapor deposition, so that the heat load increases and oligomers are generated, which results in an error or the film is formed at the time of vapor deposition. It is deformed by heat, and as a result, the deposited layer formed thereon is roughened, and the electromagnetic conversion characteristics are deteriorated.

The polyester film of the present invention comprises:
It is preferable that the film has a thickness of less than 7 μm, more preferably 1 μm or more and less than 7 μm, particularly preferably 2 μm or more and 6.5 μm or less.

The composite polyester film of the present invention is suitable for use as a base film of a magnetic recording medium comprising a ferromagnetic metal thin film layer, particularly when used for digital video tapes, since excellent results can be obtained, and thus it is suitable. Also, excellent results can be obtained for data storage tape applications, which is preferable.

The magnetic recording medium according to the present invention is characterized in that a ferromagnetic metal thin film layer is provided on the outside of the coating layer A. As the metal, any known metal can be used, and the metal is not particularly limited. , Cobalt, nickel, chromium or their alloys are preferable. The thickness of the metal thin film layer is preferably from 100 to 300 nm. The magnetic recording medium has a surface (B) opposite to the surface on which the film layer A is formed.
A back coat layer formed by applying a solution composed of solid fine particles and a binder and adding various additives as necessary may be provided on the (surface). Solid particulates, binders,
Various additives can be used, and are not particularly limited, but the thickness of the back coat layer is preferably 0.3 to 1.5 μm.

The composite polyester film of the present invention is prepared by applying a coating solution for forming the coating layer A on one side of the polyester film after stretching in one direction in an ordinary plastic film production process comprising melting, molding, biaxial stretching and heat setting. After applying and drying, it can be manufactured by stretching in a perpendicular direction and heat fixing. A known method can be applied as a coating method. For example, a roll coating method, a gravure coating method, a roll brushing method, a spray coating method, an air knife method, an impregnation method, a curtain coating method, or the like can be used alone or in combination.

[Method of measuring substances and evaluating their effects]
The method for measuring properties and the method for evaluating effects in the present invention include:
It is as follows. (1) Preparation of Acrylic-Polyester Resin Sample A sample for measuring the properties of the acrylic-polyester resin for the coating layer A to be laminated on the polyester film was prepared by taking an appropriate amount of an acrylic-polyester resin aqueous dispersion on a glass Petri dish and drafting the same. An air-dried sample is obtained by drying at room temperature under a slight reduced pressure in the inside, and this is used.

(2) Number Average Molecular Weight of Acrylic-Polyester Resin An air-dried acryl-polyester resin was dissolved in chloroform, and a GPC column (TSK-gel manufactured by Toyo Soda Co., Ltd.) was used.
GMH HR-M × 2) with a RI detector. (Chloroform in mobile phase) In quantifying the molecular weight, monodisperse polystyrene (EasiCal PS-1 manufactured by Polymer Laboratories) is used as a standard sample for a calibration curve.

(3) Ta of acrylic-polyester resin
nδ maximum peak temperature (Tδ) Air-dried acrylic-polyester resin is heat-treated at 140 ° C for 30 minutes, and the obtained sample is cut into a strip having a length of 3 cm × a width of 3 mm × a thickness of about 300 µm, using a dynamic viscoelastic device. Measurement frequency 10Hz, dynamic displacement ± 25 × 10 ^-4 c
The tan δ is determined by m, and is indicated by the highest peak temperature at this time.

(4) Composition of Acrylic-Polyester Resin An air-dried acryl-polyester resin is dissolved in deuterated DMSO, and measured at 80 ° C. by 600 MHz- ¹ H-NMR manufactured by JEOL.

(5) Average Particle Size of Inactive Particles The equivalent spherical diameter of particles at 50% by weight of all particles determined by the light scattering method is defined as the average particle size.

(6) Volume Shape Factor A photograph of each particle is taken with a scanning electron microscope at a magnification corresponding to the size of the particle, and the maximum diameter of the projected surface and the volume of the particle are calculated using an image analysis processor Luzex. Then, it is calculated by the following equation.

[0046]

Equation 4] f = in V / d ³ formula, f is the volume shape factor, V is the volume of the particle (μm ^3),
d represents the maximum diameter (μm) of the projection surface.

(7) Height and half width of projections Atomic force microscope Nano manufactured by Digital Instruments
This is performed using Scope III. Using a J scanner,
The area of 2 μm is measured under the following conditions, and the height and the half width of each projection are measured from the AFM image. Deep needle: single crystal silicon nitride Scanning mode: tapping mode Number of pixels: 246 × 256 Scanning speed: 2.0 Hz Measurement environment: room temperature, in the air The height of the projection is defined by the height h from the reference line to the top. You. The height of the projections is an average value of 100 projections. The half-value width w of the projection is represented by the length of a line where the projection intersects a straight line parallel to the reference line at a height of h / 2 from the reference line. The height / half width ratio (h / w) is represented by the average value of the analysis of 100 protrusions. The reference line is the center line of the profile excluding the profile of the protrusion in the cross-sectional profile of the 2 μm area.

(8) Thickness of film layer A small piece of the film was fixedly formed with epoxy resin, and an ultrathin section (cut in parallel to the film flow direction) of about 60 nm thickness was prepared with a microtome. Is observed with an equivalent electron microscope (H-800, manufactured by Hitachi, Ltd.).
The layer thickness is determined from the boundary line of the layer.

(9) Surface Roughness of Film Ra According to JIS B0601, a stylus type surface roughness meter (Surfcoder SE30FAT) manufactured by Kosaka Laboratories Co., Ltd. was used. It is determined under the conditions of a cutoff of 0.08 mm and a measurement length of 1.25 mm.
The measurement was performed four times, and the average value was shown.

(10) Unevenness of coating 1
After immersion for 0 minutes and washing with water, observation was carried out by silent observation. Methylene blue: 0.5% by weight Benzyl alcohol: 1.5% by weight Kayakaran red: 0.1% by weight Rhodamine B: 0.1% by weight Deionized water: 97.8% by weight

(11) Winding property of film The winding tension is 10 kg / m and the winding contact pressure is 1
Under the conditions of 40 kg / m, a winding speed of 100 m / min, an oscillation width of 100 mm, and an oscillation speed of 10 mm / min, ten polyester film rolls having a width of 500 mm and a length of 9000 m are wound up, and after standing for 24 hours, the rolls are inspected. A roll having no wrinkles is evaluated as a good product according to the following criteria.

(12) Production of Magnetic Tape and Evaluation of Characteristics A 110 nm thick cobalt-oxygen thin film was formed on the outer side of the coating layer A of the composite polyester film by vacuum evaporation, and then a sputtering was performed on the cobalt-oxygen thin film layer. A diamond-like carbon is formed to a thickness of 10 nm by the method, a fluorine-containing carboxylic acid-based lubricant is further provided sequentially, and then a back coat layer made of carbon black, polyurethane, and silicone is provided on the opposite surface to a thickness of 500 nm, and a width of 8 mm is set by a slitter. Slit to 6.35 mm and wind up on a commercially available reel to make a magnetic tape. For the electromagnetic conversion characteristics, the video S / N ratio is determined using a commercially available Hi8 type 8 mm video tape recorder, and the number of dropouts (DO) is determined using a commercially available digital video tape recorder with a built-in camera.

For the measurement of S / N, a signal is supplied from a TV test signal generator, and a video noise meter is used to compare and examine a commercially available standard Hi8ME tape with zero decibel (dB). ：: +2 dB or more compared to a commercial tape Δ: -2 dB or more to less than +2 dB compared to a commercial tape ×: Less than -2 dB compared to a commercial tape

The measurement of the number of DOs was performed using the 6.35 mm
After recording the tape with a commercially available digital video tape recorder with a built-in camera, the tape is played back for one minute and the number of block mosaics appearing on the screen is counted by a dropout counter. ：: 15 pieces / min or less △: 16-30 pieces / min ×: 31 pieces / min or more

The running durability is determined by measuring the S / N after repeating recording and reproduction 500 times at 40 ° C. and 80% RH, and determining the deviation from the initial value. ：: +0.0 dB or more with respect to the initial value Δ: -1.0 dB or more to less than +0.0 dB with respect to the initial value ×: less than -1.0 dB with respect to the initial value

[0056]

Next, the present invention will be further described based on examples.

[Example 1] Pellets of polyethylene-2,6-naphthalenedicarboxylate containing substantially no inert particles were dried at 170 ° C for 6 hours and then supplied to an extruder and melted at 305 ° C. . The molten polymer is filtered by a known method, extruded from an extruder into a sheet,
This was cooled and solidified on a casting drum to produce an unstretched film. The unstretched film thus obtained is preheated at 120 ° C., further heated by a IR heater at 900 ° C. from 15 mm above between low-speed and high-speed rolls and stretched 3.7 times in the longitudinal direction. Each of the aqueous dispersions having the following compositions was applied to a film.

Coating layer A: (1) 75% by weight of acrylic-polyester resin Polyester resin component: terephthalic acid (55 mol%), isophthalic acid (40 mol%), 5-sodium sulfoisophthalic acid (5 mol%) / Ethylene glycol (80 mol%), cyclohexane dimethanol (20 mol%)-Acrylic resin component: methyl methacrylate (75 mol%), glucidyl methacrylate (20 mol%), n-butyl acrylate (5 mol%)-Polyester resin Component / Acrylic resin component molar ratio = 3/7 Number molecular weight: 150,000 Tδ: 95 ° C. (2) Acrylic resin particles (average particle size: 20 nm) 5% by weight (3) Surfactant NONION NS- manufactured by NOF Corporation 240 20% by weight-Thickness of film layer A (after drying): 4.8 nm

Coating layer B: (1) Copolymerized polyester 60% by weight 97% by mole of terephthalic acid / 1% by mole of isophthalic acid / 5% by mole of 5-sodium sulfoisophthalic acid // 60% by mole of ethylene glycol / diethylene glycol 40 Molar% (2) Acrylic resin particles (average particle size: 60 nm) 10% by weight (3) Hydroxypropyl methylcellulose 20% by weight (4) Nippon Oil & Fats Nonion NS-208.5 10% by weight Thickness of coating layer B (after drying) ): 15 nm

Subsequently, the mixture was supplied to a stenter, stretched 4.9 times in the transverse direction at 150 ° C., and further stretched at 200 ° C. to 1.14.
The film was heat-treated while being stretched twice to obtain a biaxially oriented film having a thickness of 4.7 μm. A cobalt-oxygen thin film having a thickness of 110 nm was formed on the polyester film surface A by vacuum evaporation. Next, a diamond-like carbon having a thickness of 10 nm was formed on the cobalt-oxygen thin film layer by a sputtering method. Subsequently, a back coat layer made of carbon black, polyurethane, and silicone was provided to a thickness of 500 nm, slit to a width of 8 mm by a slitter, and wound on a reel to produce a magnetic tape. Tables 1 and 2 show the properties of the obtained composite polyester film and magnetic tape.

[Examples 2 to 4, Comparative Examples 1 to 3]
A composite polyester film and a magnetic tape were obtained in the same manner as in Example 1, except that the molecular weight of the acrylic-polyester resin on the side of the coating layer A side, the value of Tδ, and the ratio of the acrylic resin component were changed as shown in Table 1. . The characteristics are shown in Tables 1 and 2.

Example 5 In the production of a base film, polyethylene-2,6-naphthalenedicarboxylate was changed to polyethylene terephthalate, the drying time of the pellets was 3 hours, the melt extrusion temperature was 295 ° C., and the film was longitudinally stretched. The preheating temperature and the magnification were set to 80 ° C. and 3.0 times, respectively, and the same coating solution as in Example 1 was applied. Further, the film was horizontally stretched 3.3 times at 105 ° C. and further 1.6 times at 210 ° C. The film was heat-treated while the other conditions were the same, and a film having a thickness of 6.4 μm was obtained in the same manner. Tables 1 and 2 show the properties of the obtained composite polyester film and magnetic tape.

Example 6 The production of the base film of Example 1 was repeated except that 0.02% by weight of spherical silica having an average particle size of 60 nm was contained in polyethylene-2,6-naphthalenedicarboxylate. A film having a thickness of 4.7 μm was obtained in the same manner as in Example 1, and a magnetic tape was formed in the same manner as in Example 1. Tables 1 and 2 show the properties of the obtained composite polyester film and magnetic tape.

Example 7 In the production of the base film of Example 1, raw material A, which is polyethylene-2,6-naphthalenedicarboxylate containing substantially no inert particles, and substantially inert particles were used. The raw material B containing 0.3% by weight of silica having an average particle size of 300 nm in polyethylene-2,6-naphthalenedicarboxylate not containing was coextruded at a ratio of 5: 1 in thickness, and the other conditions were the same. A 4.7 μm thick composite polyester film was obtained, and a magnetic tape was prepared in the same manner as in Example 1. Tables 1 and 2 show the properties of the obtained composite polyester film and magnetic tape.

[Comparative Example 4] In the manufacture of the base film of Example 1, the thickness was 4.7 in the same manner except that the coating layer B was used instead of the coating layer A, and the coating layers B were formed on both sides.
A μm composite polyester film was obtained, and a magnetic tape was prepared in the same manner as in Example 1. Tables 1 and 2 show the properties of the obtained composite polyester film and magnetic tape.

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[Table 1]

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[Table 2]

As is clear from Tables 1 and 2, the polyester film of the present invention has no coating unevenness and is excellent in handling properties.
A tape with excellent properties and running durability.

Continued on front page F-term (reference) 4F100 AA37 AA40 AB01C AB15 AK25B AK41A AK41B AK42A BA02 BA03 BA07 BA10A BA10C BA13 BA16 DE01B EH66 EJ38 GB41 JA04B JA07B JG06C JK14A JM02C YY00 YY00AY03 A03 A03 BA03 CA02 CA06 CB04A CB05A CB06A CC06A FC35 FC36 KH01 4J031 AA20 AA49 AB01 AC03 AD01 AF28 5D006 CB01 CB05 CB07 CB08

Claims (8)

[Claims] 1. A composite film in which a film layer A containing an acryl-polyester resin is laminated on at least one surface of a polyester film, wherein the acryl-polyester resin has (1) a number average molecular weight of 10,000 or more and 1,000,000 or less. (2) a composite polyester film having at least one tan δ peak, and (3) having a maximum temperature peak temperature (T δ) of tan δ of 60 ° C or more and 110 ° C or less. 2. The acrylic-polyester resin has a polyester resin component / acryl resin component molar ratio of 1/9 or more and 5/5 or less, and the acrylic resin component comprises (A) an alkyl methacrylate (M _A ) of 50 mol% or more and 95% or more. hereinafter mol%, (B) an epoxy group-containing acrylic monomer (M _B)
A component composed of 3 mol% or more and 35 mol% or less, and (C) an alkyl acrylate (M _c ) 3 mol% or more and 30 mol% or less, which satisfies the following formulas (1) and (2). The composite polyester film according to claim 1, wherein 1 ≦ M _A / (M _B + M _C ) ≦ 10 (1) 0.1 ≦ M _B / M _C ≦ 20 (2) 3. A coating layer A comprising: (1) 40% by weight or more and 89% by weight or less of acrylic-polyester resin; and (2) 1% by weight or more of inert particles having an average particle size of 5 nm or more and 50 nm or less.
0% by weight or less, and (3) 10% by weight or more of a surfactant 5
0% by weight or less as a main component, the height / half-width ratio of the projections formed by the inert particles is 0.3 or more and 0.8 or less, and the surface of the polyester film on which the coating layer A is formed. Surface roughness Ra of the surface opposite to (B surface) is 2n
3. The composite polyester film according to claim 1, wherein the thickness is from m to 10 nm. 4. The composite polyester film according to claim 1, wherein the polyester film is a film composed of polyethylene terephthalate or polyethylene-2,6-naphthalenedicarboxylate. 5. The composite polyester film according to claim 1, wherein the thickness of the film is less than 7 μm. 6. The composite polyester film according to claim 1, wherein the surface of the film layer A of the film is a surface on which the ferromagnetic metal thin film layer of the magnetic layer is provided. 7. The composite polyester film according to claim 6, which is used for a digital recording type magnetic tape. 8. A magnetic recording medium using the composite polyester film according to claim 6 as a support film.