JP2002248722A - Laminated polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated polyester film which is excellent in heat- resistance and processing suitability, and provides an excellent electromagnetic conversion characteristics when being made into a metal film type magnetic recording medium. SOLUTION: This laminated polyester film comprises a polyester layer A and a polyester layer B. In this case, the polyester layer A contains 0.1 to 2.5 wt.% of a diethylene glycol component. The polyester layer B is laminated on one surface of the layer A, and contains 1 to 50 ppm of germanium atoms. Also, the polyester layer B contains 0.001 to 1 wt.% of an inert particle B. In this case, the average particulate diameter of the inert particle B is larger than that of an inert particle A in the layer A, and the average particulate diameter is 50 to 1,000 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated polyester film, and more particularly, to a magnetic recording medium having excellent electromagnetic conversion characteristics and running durability, and in particular, a ferromagnetic metal thin film type magnetic recording medium for recording and reproducing digital signals, for example, The present invention relates to a laminated polyester film useful as a base film for video cassette tapes, data storage tapes, and the like.

[0002]

2. Description of the Related Art In recent years, remarkable progress has been made in increasing the density of magnetic recording media. For example, a magnetic recording medium in which a ferromagnetic metal thin film is formed on a non-magnetic support by a physical deposition method such as vacuum evaporation or sputtering or a plating method. Recording media are being developed and put to practical use. Specifically, a vapor deposition tape of Co (Japanese Patent Application Laid-Open No. 54-147010) and a perpendicular magnetic recording medium made of a Co—Cr alloy (Japanese Patent Application Laid-Open No. 52-134706)
Is known.

A conventional coating type magnetic recording medium (a magnetic recording medium obtained by mixing a magnetic powder into an organic polymer binder and coating it on a non-magnetic support) has a magnetic layer as thick as about 2 μm or more. The recording density is low and the recording wavelength is long. On the other hand, the metal thin film (magnetic layer) in the ferromagnetic metal thin film type magnetic recording medium has a very small thickness of 0.2 μm or less.

For this reason, the extent to which the surface condition of the nonmagnetic support (base film) affects the surface properties of the magnetic layer is much greater for a metal thin film. That is, in the case of a ferromagnetic metal thin film type magnetic recording medium, the surface state of the non-magnetic support is directly expressed as surface irregularities of the metal thin film, which is recorded / recorded.
This causes noise in the reproduced signal. Therefore, it is desirable that the surface of the nonmagnetic support is as smooth as possible.

On the other hand, from the viewpoint of handling such as transporting, winding and unwinding of the non-magnetic support in the film forming and processing steps, it is preferable that the film has excellent slipperiness. If the film surface is too smooth, the slipperiness between the film films deteriorates, and the surface is liable to be scratched, resulting in a decrease in product yield and an increase in manufacturing cost. Therefore, the surface of the nonmagnetic support is preferably as rough as possible from the viewpoint of manufacturing cost.

[0006] In the case of a metal thin film type magnetic recording medium, in order to improve the adhesion between the metal thin film and the base film, the surface of the base film is usually called ion bombardment before forming the metal thin film. An activation process is performed. At the time of forming the metal thin film, since a considerably high temperature is applied to the film surface, the back surface of the film is cooled so that the base film does not melt or physical properties such as mechanical properties do not deteriorate. For this backside cooling, a method of winding a film around a drum-shaped cooling body is usually employed. At this time, both ends of the base film are masked so that a thin metal film is not formed on the surface of the drum.

Therefore, at both ends of the film roll that has passed through the above-mentioned vapor deposition step, portions where the metal thin film has not been formed by this masking are continuously formed in the longitudinal direction while the surface is activated by ion bombardment. Exists. Then, when this portion is wound up in a roll shape, the portion comes into contact with the opposite surface side with high force, and blocking is easily caused. When manufacturing a metal thin film type magnetic recording medium, after depositing a metal thin film, a back coat layer and a top coat layer are provided if necessary. There is a problem that the film is easily cut or wrinkled, and the yield is greatly reduced. In order to prevent this blocking, the surface of the nonmagnetic support is preferably rough.

As described above, the surface of the nonmagnetic support is required to be smooth from the viewpoint of electromagnetic conversion characteristics.
Roughness is required from the viewpoint of handleability, manufacturing cost, and prevention of blocking.

In order to satisfy the above conflicting requirements,
A laminated film composed of two layers, the surface of one layer being rougher than the surface of the other layer (for example, Japanese Patent Publication No. 1-2633)
No. 8) has been proposed. However, due to the effect of the high protrusions on the rough surface being transferred to the flat surface and the large particles added to the rough surface being pushed up to the flat surface, this laminated film has an electromagnetic conversion characteristic when used as a magnetic recording medium. Has the problem of becoming worse.

Also, catalyst residues (fine particles) inside the film
As a measure for preventing the surface smoothness from being lowered by the above method, a laminated film using a polyester containing a specific amount of germanium and phosphorus as a raw material of a smooth layer using a germanium compound as a polymerization catalyst (for example, Japanese Patent Laid-Open No. 12-1)
No. 5,695). Although the use of a germanium compound is advantageous in suppressing the formation of fine particles, it increases diethylene glycol, which is a by-product during polyester production, and deteriorates thermal stability during film production or the above-mentioned metal thin film processing step. There is a problem that the smoothness of the layer is reduced.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the above-mentioned drawbacks of the prior art and to provide a metal-deposited thin film type magnetic recording medium having excellent running properties, blocking resistance, thermal stability and workability. An object of the present invention is to provide a laminated polyester film having excellent electromagnetic conversion characteristics and running durability.

[0012]

The object of the present invention is to provide, according to the present invention, a diethylene glycol component of 0.1 to 2.5.
Polyester layer A containing 1% to 50% by weight of a germanium element laminated on one surface of the layer A and having an average particle size larger than the inert particles A in the layer A and having an average particle size of 50 to 50%. 0.001 inactive particles B of 1000 nm
This is achieved by a laminated polyester film comprising a polyester layer B containing 〜1% by weight.

In a preferred embodiment of the present invention, the ten-point average roughness (WRzB) of the surface of the polyester layer B is 30 to 30.
0 nm, the polyester layer B contains (partially saponified) ester wax composed of an aliphatic monocarboxylic acid having 8 or more carbon atoms and a polyhydric alcohol, and the surface roughness (WRaA) of the polyester layer A surface is 0.1-4
nm, the content of the germanium element in the polyester layer A is 0 to 10 ppm, and the polyester layer A contains substantially no particles or has a volume shape factor of 0.
Inert particles A having a particle diameter of 1 to π / 6 and an average particle diameter of 30 to 400 nm
0.001 to 0.2% by weight, the coating layer C is laminated on the surface of the polyester layer A which is not in contact with the layer B, the coating layer C has an average particle size of 10 to 50 nm, and a volume shape factor of 0. 0.5 to 30% by weight of inert particles C of 1 to π / 6
Containing, the thickness of the film is 2 μm or more and less than 8 μm, the polyester of the layer A or the layer B is polyethylene terephthalate or polyethylene-2,6-naphthalate, and the surface of the polyester layer A or the coating layer C is The surface includes a surface on which a magnetic layer is provided, and the magnetic layer is a ferromagnetic metal thin film layer.

The present invention also includes a magnetic recording medium using the above-mentioned laminated polyester film as a support.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The laminated polyester film of the present invention is a laminated film in which a polyester layer B is laminated on one side of a polyester layer A.

Examples of the polyesters A and B forming the polyester layer A and the layer B include aliphatic polyesters and aromatic polyesters, and aromatic polyesters are particularly preferred. Polyesters A and B may be the same type or different types.

As the aromatic polyester, polyethylene terephthalate, polyethylene isophthalate,
Examples thereof include polytetramethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate, and polyethylene-2,6-naphthalate (polyethylene-2,6-naphthalenedicarboxylate). Of these, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferred.

These polyesters may be homopolyesters or copolyesters. In the case of a copolyester, for example, as a copolymerization component of polyethylene terephthalate or polyethylene 2,6-naphthalate, diethylene glycol, propylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, polyethylene glycol, 1,4-cyclohexanediene Other diol components such as methanol, p-xylylene glycol, adipic acid,
Others such as sebacic acid, phthalic acid, isophthalic acid, terephthalic acid (for polyethylene-2,6-naphthalate), 2,6-naphthalenedicarboxylic acid (for polyethylene terephthalate), 5-sodium sulfoisophthalic acid And an oxycarboxylic acid component such as p-oxyethoxybenzoic acid. As long as the effects of the present invention are not impaired, the amount of these copolymer components is 20 mol% or less, and furthermore, 10 mol%.
The following is preferred.

Further, trimellitic acid, pyromellitic acid,
A trifunctional or higher functional compound such as pentaerythritol can be copolymerized. In this case, it is preferable to copolymerize the polymer in a substantially linear amount, for example, 2 mol% or less.

The copolymer components other than polyethylene terephthalate and polyethylene-2,6-naphthalate may be considered in the same manner as described above.

Further, as long as the effects of the present invention are not impaired, additives such as pigments, dyes, antioxidants, antistatic agents, light stabilizers, light-shielding agents (for example, carbon black, titanium oxide, etc.) may be added to the above polyester. Agents can be included as needed.

In the laminated polyester film of the present invention, the polyester layers A and B are preferably made of the same polyester, but may be made of different polyesters. For example, a laminated film in which both the layer A and the layer B are made of polyethylene terephthalate or polyethylene-2,6-naphthalate is preferable, but the layer A (or the layer B) is polyethylene terephthalate, and the layer B (or the layer A) is polyethylene-2, It may be a laminated film composed of 6-naphthalate.

In the present invention, the polyester A forming the polyester layer A is obtained by-produced during the production process or added with diethylene glycol (DE) added as a copolymerization component.
The content of the component G) needs to be in the range of 0.1 to 2.5% by weight. Preferably it is 0.2 to 2.2% by weight,
Particularly preferably, it is in the range of 0.3 to 2.0% by weight. If the amount of DEG contained in the polyester A is less than 0.1% by weight, the productivity of the polymer is remarkably reduced, which is not preferable. On the other hand, if the amount of DEG exceeds 2.5% by weight, the heat resistance in the step of depositing a metal thin film when manufacturing a metal thin film type magnetic recording medium is insufficient, and sufficient flatness cannot be obtained. Is not preferred.

The polyester A forming the polyester layer A can be produced by a conventionally known method. For example, polyethylene terephthalate can be produced by an esterification reaction of terephthalic acid and ethylene glycol or a transesterification reaction of dimethyl terephthalate and ethylene glycol, followed by polycondensation of the reaction product.

The polyester obtained by the above-mentioned method (melt polymerization) can be converted into a polymer having a higher degree of polymerization, if necessary, by a polymerization method in a solid state (solid state polymerization).

In this polymerization, a known catalyst can be used. As the transesterification catalyst in the melt polymerization, manganese, calcium, magnesium, titanium oxide, chloride, carbonate, carboxylate and the like are preferable. Acetates, that is, manganese acetate, calcium acetate, magnesium acetate, and titanium acetate are preferably exemplified.

[0027] Examples of the polycondensation catalyst include an antimony compound, a titanium compound and a germanium compound.

Preferred examples of the antimony compound include antimony trioxide, antimony pentoxide, and antimony acetate.

As the titanium compound, an organic titanium compound is preferably mentioned, for example, JP-A-5-29867.
No. 0 can be mentioned. To further explain, an alcoholate or an organic acid salt of titanium, a reaction product of a tetraalkyl titanate with an aromatic polycarboxylic acid or an anhydride thereof, and the like can be exemplified. Preferred specific examples include titanium tetrabutoxide, titanium isopropoxide, and titanium oxalate. , Titanium acetate, titanium benzoate, titanium trimellitate, and a reaction product of tetrabutyl titanate and trimellitic anhydride.

Further, the germanium compound includes:
For example, those described in Japanese Patent No. 2792068 can be mentioned. More specifically, (a) amorphous germanium oxide, (b) crystalline germanium, (c) a solution of germanium oxide dissolved in glycol in the presence of an alkali metal or alkaline earth metal or a compound thereof, and (d) Examples thereof include a germanium oxide glycol solution prepared by dissolving germanium oxide in water, adding glycol thereto, and distilling off water. However, when a germanium compound is used as a polycondensation catalyst, if the amount thereof is large, the by-product D at the time of polyester synthesis is reduced.
Since the amount of EG increases and the thermal stability of the polyester layer A decreases, the germanium element (Ge) contained in the polyester A is preferably 10 ppm or less. More preferably, it is 5 ppm or less. And
In order not to lower the thermal stability, it is particularly preferable that the polyester A contains substantially no germanium element (Ge).

In order to maintain thermal stability, the polyester A preferably contains a phosphorus compound conventionally added in a polyester production process. The phosphorus compound is not particularly limited, but includes orthophosphoric acid, phosphorous acid, trimethyl phosphate, triethyl phosphate, and triethyl phosphate.
-n-butyl phosphate is preferred.

The polyester layer A in the present invention may not substantially contain particles or may contain inert particles A. When the polyester layer A contains substantially no particles, excellent electromagnetic conversion characteristics can be obtained when a magnetic recording medium is used. However, when particles are contained in a range that does not adversely affect the electromagnetic conversion characteristics, the running durability is improved. Can be achieved. Specifically, the volume shape factor is 0.1 to π /
6. It is preferable to contain 0.001 to 0.2% by weight of the inert particles A having an average particle diameter of 30 to 400 nm with respect to the polyester layer A.

Preferred inert particles A include, for example,
(1) heat-resistant polymer particles (for example, crosslinked silicone resin, crosslinked polystyrene, crosslinked acrylic resin, melamine-
Particles composed of formaldehyde resin, aromatic polyamide resin, polyimide resin, polyamideimide resin, crosslinked polyester, etc.), (2) metal oxides (for example, aluminum oxide, titanium dioxide, silicon dioxide (silica),
Magnesium oxide, zinc oxide, zirconium oxide, etc.), (3) metal carbonates (eg, magnesium carbonate, calcium carbonate, etc.), (4) metal sulfates (eg, calcium sulfate, barium sulfate, etc.), (5) Fine particles composed of one or more of carbon (eg, carbon black, graphite, diamond, etc.) and (6) clay minerals (eg, kaolin, clay, bentonite, etc.). Among these, crosslinked silicone resin particles, crosslinked polystyrene resin particles, melamine-formaldehyde resin particles, polyamideimide resin particles, aluminum oxide (alumina), titanium dioxide, silicon dioxide, zirconium oxide, synthetic calcium carbonate, barium sulfate, diamond, or Fine particles of kaolin are preferred. More preferably, the fine particles are made of crosslinked silicone resin particles, crosslinked polystyrene resin particles, aluminum oxide (alumina), titanium dioxide, silicon dioxide, or calcium carbonate. These inert particles are 1
Species or a mixture of two or more species may be used.

The inert particles A have different average particle sizes.
When particles of more than one kind are used, fine particles such as colloidal silica or alumina having a crystal form such as α, γ, δ, θ are used as the second and third particles (fine particles) having a small average particle diameter. Is preferred. In addition, inert particles A
Among the particle types exemplified as above, fine particles having a small average particle diameter can also be used as the second and third particles (fine particles).

The shape of the inert particles A has a volume shape factor (f) described later of 0.1 to π / 6, more preferably 0.2 to π.
/ 6, particularly preferably 0.4 to π / 6. The inert particles A have an average particle size dA of 30 to 400 n.
m, even 40 to 200 nm, especially 50 to 100 nm
It is preferred that If the average particle diameter dA is less than 30 nm, the improvement in the slipperiness of the film may be insufficient, while if it exceeds 400 nm, the electromagnetic conversion characteristics of the magnetic recording medium may be poor, which is not preferable. .

When the inert particles A are contained in the polyester A, the content is preferably 0.001 to 0.2% by weight, more preferably 0.01 to 0.1% by weight, based on the polyester layer A. , Particularly preferably 0.02-
0.06% by weight. If the amount is less than 0.001% by weight, the improvement in the slipperiness of the film may be insufficient, while if it exceeds 0.2% by weight, the electromagnetic conversion characteristics of the magnetic recording medium may be poor. This is not preferred.

In the present invention, the polyester B forming the polyester layer B contains 1 to 5 germanium elements (Ge).
It is necessary to contain 0 ppm. When the amount of the germanium element (Ge) contained in the polyester B is 1 ppm or less, the projections due to the inactive particles B contained in the polyester layer B described later easily fall off in the film manufacturing process and the metal thin film forming process, and fall off. When the material is transferred to the polyester layer A to obtain a magnetic recording medium, the electromagnetic conversion characteristics are deteriorated. On the other hand, if the content exceeds 50 ppm, the thermal stability of the polyester decreases, and a film having a sufficient strength cannot be obtained.

As a method for allowing the polyester B to contain a germanium element, a method using a germanium compound as a polymerization catalyst for the polyester B is preferable. At that time, the germanium compound may be used alone or in combination with another metal compound (catalyst) other than the germanium compound (catalyst). In addition, a polyester obtained by polymerization with a germanium compound (catalyst) alone and a polyester obtained by polymerization with a metal compound (catalyst) other than the germanium compound (catalyst) are appropriately mixed to adjust the content of a necessary germanium element. You may.

Preferred examples of the germanium compound include those described in Japanese Patent No. 2792068. More specifically, (a) amorphous germanium oxide, (b) crystalline germanium, (c) a solution of germanium oxide dissolved in glycol in the presence of an alkali metal or alkaline earth metal or a compound thereof, and (d) Germanium oxide is dissolved in water, glycol is added thereto, and water is distilled off.
It is not particularly limited to this.

The polyester B, like the polyester A, can be produced by a conventionally known method. At that time, a known catalyst can be used, and it is preferable to use the same catalyst as polyester A other than the germanium compound. Further, it is preferable to contain a phosphorus compound similarly to the polyester A.

The polyester layer B in the present invention needs to contain inert particles B having a larger average particle size than the inert particles A contained in the polyester layer A. When the average particle size of the inert particles B is smaller than that of the inert particles A, problems such as blocking in a film manufacturing process and a metal thin film forming process occur. The inert particles B have an average particle size (dB) of 50 to 1,000 nm, preferably 100 to 1,000 nm.
It is 800 nm, more preferably 150 to 700 nm, particularly preferably 200 to 600 nm. And, the content of the inert particles B is set to 0.1 to the polyester layer B.
001 to 1% by weight, preferably 0.005 to 0.8% by weight, more preferably 0.01 to 0.6% by weight, particularly preferably 0.01 to 0.2% by weight.

If the average particle size of the inert particles B is less than 50 nm or the content is less than 0.001% by weight, the film has poor winding properties and blocking resistance. On the other hand, when the average particle size exceeds 1,000 nm or when the content exceeds 1% by weight, the shape of the protrusions is transferred to the surface of the polyester layer A or the protrusions from below the layer A cause the electromagnetic conversion characteristics. Worsen.

Preferred inert particles B include the same particles as the above-mentioned inert particles A, and one or more of them may be used in combination.

The polyester layer B may contain, in addition to the inert particles B, second and third particles (fine particles) having an average particle size smaller than that of the inert particles B. The average particle size of the fine particles is preferably 5 to 450 nm, more preferably 10 to 400 nm, and particularly preferably 30 to 350 nm.
nm. The content of the second and third particles (fine particles) is preferably 0.005 to 1% by weight, more preferably 0.01 to 0.7% by weight, and particularly preferably 0 to 0% by weight with respect to the layer B. 0.02 to 0.5% by weight.

The polyester layer B in the present invention preferably further contains 0.001 to 1% by weight of (partially saponified) ester wax comprising an aliphatic monocarboxylic acid having 8 or more carbon atoms and a polyhydric alcohol. . here,
The (partially saponified) ester wax includes an ester wax and a partially saponified ester wax.

The aliphatic monocarboxylic acid has 8 or more carbon atoms, preferably 8 to 34 carbon atoms. When the number of carbon atoms is less than 8, the heat resistance of the obtained (partially saponified) ester wax is insufficient, and the (partially saponified) ester wax can easily be obtained under the heating conditions when dispersing in polyester. It is inappropriate because it will be decomposed.

The aliphatic monocarboxylic acids having 8 or more carbon atoms include pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, and nonadecanoic acid. Arachiic acid, pehenic acid, lignoceric acid, cerotic acid, montanic acid, melicic acid, hentriacontanic acid, petroselinic acid, oleic acid, erucic acid, linoleic acid and mixtures containing these.

The alcohol component of the (partially saponified) ester wax is a polyhydric alcohol having two or more hydroxyl groups. Further, from the viewpoint of heat resistance, a polyhydric alcohol having three or more hydroxyl groups is preferable. When a monoalcohol is used, the heat resistance of the (partially saponified) ester wax formed is insufficient.

Examples of the polyhydric alcohol having two hydroxyl groups include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7 -Heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, diethylene glycol, triethylene glycol, polyethylene glycol and the like are preferred. As the polyhydric alcohol having three or more hydroxyl groups,
For example, glycerin, erythrit, trait, pentaerythrit, arabit, xylit, tallit, sorbit, mannitol and the like are preferably exemplified.

The ester wax obtained from the aliphatic monocarboxylic acid and the polyhydric alcohol includes monoesters, diesters and triesters, depending on the number of hydroxyl groups of the polyhydric alcohol. Of these,
From the viewpoint of heat resistance, diesters rather than monoesters,
Triesters are preferred over diesters. Preferable examples of the ester wax include sorbitan tristearate, pentaerythritol tripehenate, glycerin tripalmitate, and polyoxyethylene distearate.

The partially saponified ester wax comprising an aliphatic monocarboxylic acid and a polyhydric alcohol is obtained by partially esterifying a polyhydric alcohol with an aliphatic monocarboxylic acid having 8 or more carbon atoms, and then diluting a dihydric or higher metal water. Obtained by saponifying with an oxide. Specific examples include Wax E, Wax OP, Wax O, Wax OM, Wax FL (all trade names manufactured by Hoechst Co., Ltd.) obtained by saponifying montanic acid diol ester With calcium hydroxide. Such (partially saponified) ester waxes may be used alone or in combination of two or more.

The amount of the (partially saponified) ester wax added to the layer B is 0.001 to 1% by weight, preferably 0.003 to 0.5% by weight, and more preferably 0.001% by weight.
The content is 5 to 0.5% by weight, particularly preferably 0.01 to 0.3% by weight. If the amount of the (partially saponified) ester wax is less than 0.001% by weight, the film winding property is insufficiently improved, and the effect of improving blocking cannot be obtained. On the other hand, if the content exceeds 1% by weight, a large amount of the wax component is transferred by bleed-out to the opposite surface that comes into contact when the film is wound up on a roll in the film manufacturing process. Adverse effects such as hindering the performance.

The ten-point average roughness (WRzB) of the surface of the polyester layer B in the present invention is 30 to 300 nm, preferably 40 to 250 nm, particularly preferably 50 to 200 nm.
It is. When the WRzB is less than 30 nm, the handleability is poor, sufficient productivity cannot be improved, and the effect of improving blocking is insufficient. Meanwhile, 3
If the thickness exceeds 00 nm, the transfer of the shape of the projection to the surface on the side on which the magnetic layer on the opposite side is provided becomes large, which may impair the electromagnetic conversion characteristics, which is not preferable. The polyester layer B
Has a surface roughness (WRaB) of preferably 2 to 10 nm, and more preferably 2 nm or more than a surface roughness (WRaA) of the polyester layer A described later.

The laminated polyester film of the present invention has a coating layer C on the surface on which the magnetic layer is provided, that is, the surface of the polyester layer A which is not in contact with the polyester layer B, in order to improve various properties when a magnetic tape is formed. Is preferably provided.

The coating layer C has an average particle size of 10 to 50 n.
m and inert particles C having a volume shape factor of 0.1 to π / 6.
It is preferable to contain 5 to 30% by weight.

As the resin forming the coating layer C, for example, an aqueous polyester resin, an aqueous acrylic resin, an aqueous polyurethane resin and the like are preferable, and an aqueous polyester resin is particularly preferable.

In the aqueous polyester resin, acid components include, for example, isophthalic acid, phthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, adipic acid,
Sebacic acid, dodecanedicarboxylic acid, succinic acid, sodium 5-sulfoisophthalate, potassium 2-sulfoterephthalate, trimellitic acid, trimesic acid, monopotassium trimellitic acid, polycarboxylic acids such as p-hydroxybenzoic acid Consisting of one or more glycol components,
For example, ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,6
A polyester resin mainly composed of at least one polyvalent hydroxy compound such as -hexanediol, 1,4-cyclohexanedimethanol, p-xylylene glycol, dimethylolpropane, and an ethylene oxide adduct of bisphenol A is preferably used. Further, a graft polymer or a block copolymer in which an acrylic polymer chain is bonded to a polyester chain, or two kinds of polymers have a specific physical structure in a microparticle (IPN (interpenetrating polymer network) type, core-shell type, etc.) May be an acrylic modified polyester resin. As the aqueous polyester resin, any type which can be dissolved, emulsified, or finely dispersed in water can be used freely, but a type which is emulsified or finely dispersed in water is preferable. In order to impart hydrophilicity, a sulfonic acid group, a carboxylic acid group, a polyether unit, or the like may be introduced in the molecule.

The inert particles C contained in the coating layer C are not particularly limited, but hardly sediment in the coating liquid.
Those having a relatively low specific gravity are preferred. For example, organic particles made of heat-resistant resin such as cross-linked silicone resin, acrylic resin, polystyrene, melamine-formaldehyde resin, aromatic polyamide resin, polyamide-imide resin, cross-linked polyester, wholly aromatic polyester, silicon dioxide (silica), calcium carbonate, etc. Preferred are particles composed of the above inorganic substances. Among them, crosslinked silicone resin particles,
Acrylic resin particles, silica particles, and core-shell type organic particles (core: crosslinked polystyrene, shell: particles of polymethyl methacrylate, etc.) are particularly preferred.

The inert particles C have an average particle size (dC) of 1
It is 0 to 50 nm, preferably 12 to 45 nm, and more preferably 15 to 40 nm. This average particle size is 10 nm
If it is less than 50 nm, the slipperiness of the film may be poor. On the other hand, if it exceeds 50 nm, the electromagnetic conversion characteristics of the magnetic recording medium may be poor, which is not preferable.

The shape of the inert particles C is represented by the following formula (I)
Is 0.1 to π / 6, preferably 0.2 to π / 6, and more preferably 0.4 to π.
/ 6.

[0061]

(Equation 1)

[Where f is the volume shape factor, V is the volume of the particles (μm ³ ), and D is the average particle size of the particles (μm). ]

The shape of a particle having a volume shape factor (f) of π / 6 is a sphere (true sphere). That is, those having a volume shape factor (f) of 0.4 to π / 6 substantially include a sphere or a true sphere or an elliptical sphere such as a rugby ball, and are preferable as the inert particles C. For particles having a volume shape factor (f) of less than 0.1, for example, flaky particles,
It is not preferable because running durability is reduced.

The content of the inert particles C is determined according to the coating layer C
0.5 to 30% by weight, preferably 2 to 20% by weight, more preferably 3 to 10% by weight, based on (solid content of the coating liquid)
It is. If the content is less than 0.5% by weight, the slipperiness of the film may be poor, while 30% by weight.
Exceeding the range is not preferred because the electromagnetic conversion characteristics of the magnetic recording medium may be poor.

The laminated polyester film of the present invention has a surface roughness (WRaA) of 0.1 to 4 on the surface of the polyester layer A (or the surface of the coating layer C when the coating layer C is provided).
nm, preferably 0.2 to 3.5 nm, more preferably 0.3 to 3.0 nm, particularly preferably 0.4 to 2.5 nm.
nm. When the WRaA is less than 0.1 nm,
It is difficult to produce a film due to poor slipperiness. On the other hand, if WRaA exceeds 4 nm, electromagnetic conversion characteristics deteriorate, which is not preferable.

The surface roughness (WRaA) is adjusted by the particle size and amount of the inert particles C contained in the film layer C and / or the particle size and amount of the inert particles A contained in the polyester layer A. Can be.

The total thickness of the laminated polyester film in the present invention is preferably from 2 μm to less than 8 μm, more preferably from 2.5 to 7.5 μm. The thickness constitution of the polyester layer A and the polyester layer B is preferably such that the thickness of the layer B is 1/50 to 1 of the total thickness of the laminated film.
/ 2, more preferably 1/30 to 1/3, particularly preferably 1/20 to 1/4. The thickness of the coating layer C is usually 1 to 100 nm, preferably 2 to 50 nm, more preferably 3 to 10 nm, and particularly preferably 3 to 8 nm.

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

For example, in the case of a biaxially oriented polyester film, the above-mentioned (partially saponified) ester wax and inert gas are used in or before the extrusion die (generally, the former is called a multi-manifold type, and the latter is called a feed block type). Polyester B containing finely dispersed and contained particles B
And, if necessary, polyester A containing inert particles A, respectively, after further high-precision filtration, and then laminated and composited in a molten state to form a laminated structure having the above-mentioned preferred thickness ratio. After co-extruding into a film at a temperature of (Tm) to (Tm + 70) ° C., the mixture is rapidly cooled and solidified by a cooling roll at 40 to 90 ° C. to obtain an unstretched laminated film.
Then, the unstretched laminated film is uniaxially (longitudinal or transverse) (Tg-10) to (Tg +
70) The film is stretched at a temperature of (° C) (Tg: glass transition temperature of polyester) at a magnification of 2.5 to 8.0 times, preferably at a ratio of 3.0 to 7.5 times. Is preferably at a temperature of (Tg) to (Tg + 70) ° C. at a magnification of 2.5 to 8.0 times in a perpendicular direction (when the first-stage stretching is in the longitudinal direction, the second-stage stretching is in the transverse direction). Is 3.0-
Stretch at 7.5 times magnification. 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 1
It is 0 to 35 times, and more preferably 12 to 30 times.

Further, the biaxially oriented film is (Tg +
70) to (Tm-10) C, for example, in the case of a polyethylene terephthalate film, excellent dimensional stability is imparted by heat-setting crystallization at 180 to 250C. At that time, the heat fixing time is preferably 1 to 60 seconds.

In the production of the laminated polyester film, additives other than the above-mentioned inert particles, such as a stabilizer, a colorant, and a specific resistance modifier for the molten polymer, may be added to the polyesters A and B, if desired. .

The lamination of the coating layer C on the polyester layer A in the present invention is preferably performed by a method of applying an aqueous coating solution.

The coating is preferably performed on the surface of the polyester layer A before the final stretching treatment, and after the coating, the film is preferably stretched in at least one direction. Before or during this stretching, the film is dried. Among them, the coating is preferably performed on an unstretched laminated film or a longitudinally (uniaxially) stretched laminated film, particularly a longitudinally (uniaxially) stretched laminated film. The application method is not particularly limited, and examples thereof include a roll coating method and a die coating method.

The solid content of the 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. Further, other components, for example, other surfactants, stabilizers, dispersants, ultraviolet absorbers, thickeners, and the like can be added to the aqueous coating liquid as long as the effects of the present invention are not impaired.

In the present invention, in order to improve various performances such as head touch and running durability as a magnetic recording medium and at the same time to achieve a thinner film, the Young's modulus of the laminated film must be increased in the longitudinal and transverse directions. And usually 45
00N / mm ² or more and 6000 N / mm ² or more, preferably 4800N / mm ² or more and 6800N / mm ²
Or more, more preferably 5500N / mm ² or more and 8000 N / mm ² or more, particularly preferably 5500N /
mm ² or more and 10,000 N / mm ² or more.

The degree of crystallinity of the polyester layers A and B is desirably 30 to 50% when the polyester is polyethylene terephthalate and 28 to 38% when the polyester is polyethylene-2,6-naphthalate. 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 the guide pin surface.

According to the present invention, each of a laminated polyester film in which a polyester layer B is laminated on one side of a polyester layer A and a laminated polyester film in which a coating layer C is further laminated on the surface of the polyester layer A, Is similarly provided.

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

The laminated polyester film of the present invention comprises iron, cobalt, nickel, chromium or a main component thereof on the surface of the polyester layer A, preferably the coating layer C, by a method such as vacuum deposition, sputtering, or ion plating. It is particularly useful for forming a magnetic recording medium by forming a ferromagnetic metal thin film layer made of an alloy or an oxide, and further providing a back coat layer on the surface of the polyester layer B if necessary by a known method. The thickness of the metal thin film layer is preferably from 100 to 300 nm.

Further, the laminated polyester film is
On the surface of the ferromagnetic metal thin film layer, a protective layer such as diamond-like carbon (DLC) and a fluorinated carboxylic acid-based lubricating layer are sequentially provided on the surface of the polyester layer B, if necessary. By providing a back coat layer by a known method, the output in a short wavelength region, the electromagnetic conversion characteristics such as S / N and C / N are particularly excellent,
It is preferably used for forming a vapor-deposited magnetic recording medium for high-density recording with low dropout and error rate. This deposited magnetic recording medium is extremely useful as a magnetic tape medium for Hi8 for analog signal recording, a digital video cassette recorder (DVC) for digital signal recording, 8 mm data, and DDSIV, and is particularly excellent when used for digital video tape applications. It is possible to obtain the result, which is preferable. Also, excellent results can be obtained for data storage tape applications, which is preferable.

Further, the laminated polyester film of the present invention comprises a polyester layer A, preferably a coating layer C,
Iron or iron-based fine magnetic powder (metal powder)
Is uniformly dispersed in a binder such as polyvinyl chloride or a vinyl chloride-vinyl acetate copolymer, and applied so that the thickness of the magnetic layer is 1 μm or less, preferably 0.1 to 1 μm. By providing a back coat layer on the surface of the substrate by a known method, it is particularly excellent in output in a short wavelength region, excellent in electromagnetic conversion characteristics such as S / N, C / N, and has a low dropout and a low error rate. Metal coated magnetic recording media can also be used. If necessary, fine titanium oxide particles or the like as an underlayer (nonmagnetic layer) of the metal powder-containing magnetic layer are dispersed in the same organic binder as the magnetic layer on the surface of the polyester layer A or the coating layer C. , Can also be applied. This metal-coated magnetic recording medium includes 8 mm video for recording analog signals, Hi8, β cam SP, W-VHS, digital video cassette recorder (DV) for recording digital signals.
C), data 8mm, DDSIV, digital β cam,
It is extremely useful as a magnetic tape medium for D2, D3, SX and the like.

The laminated polyester film of the present invention may further comprise a polyester layer A, preferably a coating layer C,
Needle-like fine magnetic powder such as iron oxide or chromium oxide or plate-like fine magnetic powder such as barium ferrite is uniformly dispersed in a binder such as polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, and the magnetic layer thickness is 1 μm. Hereinafter, it is preferably applied so as to have a thickness of 0.1 to 1 μm, and if necessary, a back coat layer is provided on the surface of the polyester layer B by a known method, so that output in a short wavelength region, S
/ N, C / N, etc., and an oxide-coated magnetic recording medium for high-density recording with low dropout and low error rate. Also, if necessary,
On the surface of the polyester layer A or the coating layer C, fine titanium oxide particles and the like are dispersed and coated in the same organic binder as the magnetic layer as an underlayer (nonmagnetic layer) of the oxide powder-containing magnetic layer. Can also. This oxide-coated magnetic recording medium is useful as an oxide-coated magnetic recording medium for high-density recording such as a data streamer QIC for digital signal recording.

As described above, the magnetic recording medium according to the present invention comprises a backing layer formed by applying a solution containing solid fine particles and a binder to the surface of the polyester layer B and adding various additives as necessary. A coat layer may be provided. Known solid fine particles, binders and 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 above-mentioned W-VHS is a VTR for recording an analog HDTV signal, and DVC is a digital HDTV signal.
It is applicable for recording TV signals. Therefore, the laminated polyester films of the present invention
It can be said to be a very useful base film for a magnetic recording medium for a TV-compatible VTR.

[0085]

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

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

(2) Amount of diethylene glycol The polyester layer A was cut out, and CDCl ₃ / CF ₃ COO
Dissolve in D mixed solvent and measure by ¹ H-NMR.

(3) Germanium element amount The polyester layer B or the polyester layer A is cut out,
After wet decomposition with a 1: 1 mixture of nitric acid and sulfuric acid, a high-frequency plasma emission spectrometer (manufactured by Jarrell Ash)
Determine the amount of germanium element using Atom Comp Series 800).

(4) Average Particle Size (I) (Average Particle Size:
60nm or more) "CP-50 Centrihugle manufactured by Shimadzu Corporation"
Particle size analyzer (Centrifugal Part
particle size analyzer). The particle size “equivalent sphere diameter” corresponding to 50% by mass was read from the integrated curve of the particles of each particle size and its abundance calculated based on the obtained centrifugal sedimentation curve, and this value was calculated as the average particle size (n
m) (“Granularity measurement technology” published by Nikkan Kogyo Shimbun, 1
975, pp. 242-247).

(5) Average particle size of particles (II) (average particle size:
Particles having an average particle diameter of less than 60 nm that form small projections are measured using a light scattering method. That is, the product name “NICOMP MODEL 270 SUBMICRON PARTICLE SIZER” manufactured by Nicomp Instruments Inc.
The “equivalent spherical diameter” of the particles at 50% of all the particles determined by the above is defined as the average particle diameter (nm).

(6) Volume Shape Factor (f) A photograph of each particle was taken with a scanning electron microscope at a magnification corresponding to the size used, and the image was analyzed using a Luzex 500 image analyzer (manufactured by Nippon Regulator Co., Ltd.). The maximum diameter of the projected surface is determined as the average particle diameter (D) (μm) of the particles, and the volume (V) (μm ³ ) of the particles is calculated, and is calculated by the following equation (II).

[0092]

(Equation 2)

(7) The thickness of the polyester layers A and B and the thickness of the entire film The thickness of the entire film is randomly measured at 10 points with a micrometer, and the average value is used. For the layer thicknesses of the polyester layers A and B, the layer thickness of the thin polyester layer is measured by the method described below, and the layer thickness of the thick polyester layer is obtained by subtracting the layer thickness of the coating layer and the thin polyester layer from the total thickness. Ask. That is, using a secondary ion mass spectrometer (SIMS), a metal element (M ⁺ ) originating from the highest concentration of particles in a film having a depth of 5,000 nm from the surface layer excluding the coating layer. The concentration ratio (M ⁺ / C ⁺ ) of the hydrocarbon (C ⁺ ) to the polyester is defined as the particle concentration, and the analysis in the thickness direction is performed from the surface to a depth of 5,000 nm. In the surface layer, the particle concentration is low due to the interface of the surface, and the particle concentration increases as the distance from the surface increases.
In the case of the present invention, after the particle concentration once reaches a stable value of 1,
There are a case where it rises to a stable value of 2 and a case where it monotonously decreases. Based on this distribution curve, in the former case, the depth gives a particle concentration of (stable value 1 + stable value 2) / 2, and in the latter case, the depth at which the particle concentration becomes 1/2 of the stable value 1 (This depth is deeper than the depth that gives a stable value of 1)
And the thickness (μm) of the thin polyester layer.

The measurement conditions are as follows.

(A) Measuring apparatus Secondary ion mass spectrometer (SIMS); “6300” manufactured by PERKIN ELMER INC. (B) Measurement conditions Primary ion species: O 2 ⁺ primary ion accelerating voltage : 12 KV Primary ion current: 200 nA Raster area: 400 μm □ Analysis area: Gate 30% Measurement vacuum degree: 6.0 × 10 ^-9 Torr E-GUNN: 0.5 KV-3.0 A

In the case where organic particles other than silicone resin are the most abundant particles in the range of 5,000 nm from the surface layer, it is difficult to measure by SIMS. Therefore, FT-IR (Fourier transform red) is used while etching from the surface. Spectroscopy), XPS (X-ray photoelectric spectroscopy) for some particles
Measure the same concentration distribution curve as above, and calculate the layer thickness (μm)
Ask for.

(8) Thickness of Coating Layer C A small piece of the film was fixed and molded with an epoxy resin, and an ultrathin section (cut in parallel to the film flow direction) having a thickness of about 600 Å was prepared with a microtome.
This sample was transferred to a transmission electron microscope (Hitachi, Ltd .:
(H-800 type), and the thickness (nm) of the coating layer is determined by searching for the boundary surface of the coating layer C.

(9) Surface roughness Non-contact three-dimensional roughness meter manufactured by WRa WYKO Co., Ltd., trade name "TOPO-
Using “3D”, measurement magnification 40 times, measurement area 242 μm ×
The measurement was performed under the condition of 239 μm (0.058 mm ² ) to obtain a surface roughness profile (original data). The center plane average roughness (WRa) defined by the following equation is obtained by the surface analysis using the software built into the roughness meter.

[0099]

(Equation 3)

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

From the data obtained by measuring under the same conditions using the same measuring device as the ten-point average roughness (WRz), the surface was analyzed by the built-in roughness analyzer using the software. An average value of five points and five points from the lower of the valleys (Hv) is obtained, and is defined as WRz.

[0102]

(Equation 4)

(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 nm and a width of 12.7.
mm is pulled at a strain rate of 10% / min, and calculated by the following equation (V) using the first straight line portion of the tensile stress-strain curve.

[0104]

(Equation 5)

Here, E is Young's modulus, Δσ is 2 on the straight line.
The stress difference due to the original average cross-sectional area between points, Δε is the strain difference between the same two points.

(11) Winding properties After optimizing the winding conditions at the time of slitting, the width 600
mm × 12,000m size, 30 rolls at speed 1
The film is slit at a speed of 00 m / min, and a roll having no bumps, protrusions, or wrinkles on the film surface after the slit is regarded as a non-defective product, and the winding property is evaluated based on the following criteria. ◎: 28 or more good rolls ○: 25 to 27 good rolls ×: 24 or less good rolls

(12) Production of Magnetic Tape and Evaluation of Characteristics (Electromagnetic Conversion Characteristics) A ferromagnetic thin film of 100% cobalt was coated on the surface of the coating layer C of the laminated polyester film by a vacuum evaporation method to a thickness of 0.2 μm.
m (thickness of each layer is about 0.1 μm). A diamond-like carbon (DCL) film and a fluorine-containing carboxylic acid-based lubricating layer are sequentially provided on the surface of the formed ferromagnetic thin film, and a back coat layer is further provided on the surface of the polyester layer A by a known method. Then, it is slit into an 8 mm width and loaded on a commercially available 8 mm video cassette. Next, the properties (C / N) of the tape are measured using the following commercially available equipment. (A) Equipment used 8mm video tape recorder, manufactured by Sony Corporation, trade name "EDV-6000" Noise meter, manufactured by Shibasoku Co., Ltd. (b) Measurement method Recording a signal with a recording wavelength of 0.5 μm (frequency about 7.4 MHz) Then, the ratio between the values of 6.4 MHz and 7.4 MHz of the reproduced signal is set as the C / N of the tape, and the C / N of the commercially available 8 mm video evaporation tape is set as 0 dB, and the relative values are evaluated.

(13) (Partially saponified) ester wax Sorbitan tristearate (melting point 55 ° C.) is used as (partially saponified) ester wax comprising an aliphatic monocarboxylic acid having 8 or more carbon atoms and a polyhydric alcohol. I do.

[Example 1] Dimethyl terephthalate 10
To a mixture of 0 parts and 70 parts of ethylene glycol, 0.025 parts of manganese acetate tetrahydrate was added as a transesterification catalyst, and a transesterification reaction was performed while gradually increasing the internal temperature from 150 ° C. When the transesterification reaction reaches 95%, 0.01 part of phosphorous acid is added as a stabilizer, and the mixture is sufficiently stirred. Then, in 2.5 parts of ethylene glycol, 0.8 part of trimellitic anhydride and tetrabutyl are added. 0.65 titanate
Part reacted liquid (titanium content: 11% by weight)
014 parts were added. Further, spherical silica having an average particle size of 60 nm (volume shape coefficient of 0.
5) was added to 0.03% (based on the polymer), and the mixture was sufficiently stirred. Then, the reaction product was transferred to a polymerization reactor, and subjected to polycondensation under a high-temperature vacuum (final internal temperature: 295 ° C.) to obtain an intrinsic viscosity. A polyethylene terephthalate (resin A1) for polyester A of 0.60 was obtained. The DEG amount of the resin A1 is 1.5
% By weight.

Further, a transesterification reaction was carried out in the same manner as described above. When the transesterification reaction reached 95%, 0.01 part of phosphorous acid was added as a stabilizer, and the mixture was sufficiently stirred. 2.1 parts of a germanium water colloid solution (1% solution) was added. After sufficiently distilling water mixed into the system, the lubricant (inert particles B) has an average particle size of 30.
0 nm silicone resin particles and average particle size 100 nm
Was added to the resin at 0.05% and 0.2%, respectively, and the mixture was sufficiently stirred. Then, the reaction product was transferred to a polymerization reactor, and the mixture was heated under high-temperature vacuum (final internal temperature of 295 ° C.). Polycondensation was performed to obtain polyethylene terephthalate having an intrinsic viscosity of 0.60. The residual amount of germanium element in this polymer was 40 ppm.

The obtained polyethylene terephthalate 9
9.7% sorbitan tristearate (melting point 55) as an ester wax (partially saponified) consisting of an aliphatic monocarboxylic acid having 8 or more carbon atoms and a polyhydric alcohol.
C)), and kneaded with a vented biaxial rudder, polyester layer B having an intrinsic viscosity of 0.59.
Polyethylene terephthalate (resin B1) was obtained.

After the obtained resin A1 and resin B1 were dried at 170 ° C. for 3 hours, respectively, they were supplied to two extruders.
Melted at a melting temperature of 280 to 300 ° C, with an average opening of 11
After high-precision filtration with a μm steel wire filter, the layer B is applied to one side of the layer A using a multi-manifold type coextrusion die.
And quenched to obtain an unstretched laminated polyester film having a thickness of 89 μm.

The obtained unstretched film was preheated, and further between a low-speed and high-speed roll at a film temperature of 100 ° C.
The film was stretched three times and rapidly cooled to obtain a longitudinally stretched film. Next, an aqueous coating solution (total solid concentration: 1.0%) having the following composition (in terms of solid content) was applied to the layer A side of the longitudinally stretched film by a kiss coating method.

Solid content composition of coating liquid Binder: Acrylic-modified polyester (IN-170-6 manufactured by Takamatsu Oil & Fat Co., Ltd.) 60% Inactive particles C: Acrylic filler (average particle size: 30 nm) (volume shape factor: 0.40) ( 7% Surfactant X: (Nonion NS-208.5, manufactured by NOF Corporation) 3% Surfactant Y: (Nonion NS-240, manufactured by NOF Corporation) 30% C layer thickness (after drying): 8 nm

Subsequently, the mixture was supplied to a stenter and heated at 110 ° C.
The film was stretched 4.2 times in the transverse direction. The obtained biaxially stretched fill
The sample was heat-set with hot air at 220 ° C. for 4 seconds to give a total thickness of 6.4.
μm, 1.0 μm thick polyester layer B laminated biaxial
An oriented polyester film was obtained. Poly of this film
For the thickness of the ester layers A and B, two extruders
Was adjusted according to the discharge amount. The film layer C side of this film
The surface roughness WRa measured from the surface is 1.7 nm.
The Young's modulus of the film is 5000 N / mm in the vertical direction ^Two, Sideways
7000 N / mm^TwoMet. This laminated film
Other properties and the ferromagnetic thin film evaporation using this film
Table 1 shows the characteristics of the wearable magnetic tape.

Example 2 As a resin B1, a mixture of 100 parts of bis-β-hydroxyethyl terephthalate, 65 parts of terephthalic acid and 29 parts of ethylene glycol was subjected to an esterification reaction at a temperature of 210 to 230 ° C. . The reaction was terminated when the amount of distilled water generated by the reaction reached 13 parts, and 2.1 parts of a germanium oxide aqueous colloid solution (1% solution) was added per 100 parts of the reaction product. Next, the reaction product was transferred to a polymerization reactor and subjected to a polycondensation reaction under a high-temperature vacuum (final internal temperature of 290 ° C.) to obtain a polyethylene terephthalate (resin B2-
1) was obtained. The amount of germanium remaining in the polymer is 4
It was 0 ppm.

Further, to a mixture of 100 parts of dimethyl terephthalate and 70 parts of ethylene glycol, 0.025 part of manganese acetate tetrahydrate as a transesterification catalyst was added.
The transesterification reaction was performed while gradually increasing the internal temperature from 150 ° C. When the transesterification reaches 95%,
After adding 0.01 parts of phosphorous acid as a stabilizer and sufficiently stirring, 0.02 parts of antimony trioxide is added, and as a lubricant (inactive particles B), silicone resin particles having an average particle diameter of 300 nm and an average particle diameter of 100 nm are used. After adding 0.10% and 0.4% of θ-alumina to the resin, respectively, and stirring the mixture sufficiently, the reaction product was then transferred to a polymerization reactor and subjected to high-temperature vacuum (final internal temperature: 295 ° C.) Polycondensation was performed to obtain polyethylene terephthalate having an intrinsic viscosity of 0.60.

The obtained polyethylene terephthalate 9
To 9.7%, 0.30% of powder of sorbitan tristearate (a-1) was dusted and kneaded with a biaxial rudder with a vent, and polyethylene terephthalate for polyester layer B having an intrinsic viscosity of 0.59 (resin B2 -2) was obtained.

Resins B2-1 and B2-2
Was mixed in a ratio of 1: 1 to obtain a resin B2, and a laminated biaxially oriented polyester film was obtained in the same manner as in Example 1. Table 1 shows the properties of the obtained film and the properties of a ferromagnetic thin film-deposited magnetic tape using the film.

[Example 3] The particles were not contained in the polyester layer A (resin A2), and the type, the average particle diameter and the amount of the inert particles B contained in the polyester layer B were changed as shown in Table 1. Example 1 except for (Resin B3)
A laminated polyester film was obtained in the same manner as described above. Table 1 shows the properties of the obtained film and the properties of a ferromagnetic thin film-deposited magnetic tape using the film.

Example 4 Polyester layers A and B were prepared in the same manner as in Example 3 except that dimethyl 2,6-naphthalenedicarboxylate was used in the same molar amount instead of dimethyl terephthalate in polyester layer A and polyester layer B. 2,6-naphthalate (PE
N) (resins A3 and B4) were obtained. The intrinsic viscosity is resin A3,
B4 was 0.60. The DEG amount of the resin A3 was 1.2% by weight.

The resins A3 and B4 were heated at 170 ° C.
After drying for 6 hours in the same manner as in Example 1, the thickness of each layer was adjusted to obtain an unstretched laminated thermoplastic resin film having a thickness of 89 μm.

The obtained unstretched film was preheated, and further between a low-speed and high-speed roll at a film temperature of 135 ° C.
The film was stretched 6 times and quenched to obtain a vertically stretched film. Next, on the layer A side of the longitudinally stretched film, an inert particle C was coated with a core-shell filler (core; crosslinked polystyrene, shell; polymethyl methacrylate) (average particle diameter: 30 nm, volume shape factor: 0.45) manufactured by JSR Corporation, SX 872
An aqueous coating liquid having the same composition as in Example 1 (total solid concentration: 1.0%) was applied in the same manner as in Example 1 except that the composition was changed to "1".

Subsequently, it was supplied to a stenter and stretched 5.7 times in the horizontal direction at 155 ° C. The obtained biaxially stretched film was heat-set with hot air at 200 ° C. for 4 seconds to obtain a total thickness of 4.4.
A layered biaxially oriented polyester film having a thickness of μm and a thickness of layer B of 0.6 μm was obtained. Polyester layer A of this film,
The thickness of B was adjusted by the discharge rates of the two extruders. The surface roughness WRa measured from the surface on the coating layer C side of this film is 1.2 nm, the Young's modulus of this film is 5500 N / mm ^{2 in} the vertical direction, and 10,500 in the horizontal direction.
N / mm ² . Table 1 shows other characteristics of the laminated film and characteristics of a ferromagnetic thin film-deposited magnetic tape using this film.

Comparative Example 1 A polycondensation catalyst for the resin B forming the polyester layer B was polycondensed by adding 0.03 part of antimony oxide instead of germanium oxide.
A laminated polyester film was obtained in the same manner as in Example 1. The resulting film has a severe degree of transfer to the opposite surface derived from the falling off of the protrusions of the polyester layer B during film running,
When a magnetic tape was used, sufficient electromagnetic conversion characteristics could not be obtained. Table 1 shows other characteristics and the characteristics of the ferromagnetic thin film-deposited magnetic tape using this film.

Comparative Example 2 The polycondensation catalyst for the resin A forming the polyester layer A was 0.02 as germanium oxide.
In addition, a laminated polyester film was obtained in the same manner as in Example 1, except that the resin A having a DEG amount of 3.0% by weight was used after polycondensation was performed. In the obtained film, the flatness of the layer A was reduced in the metal thin film deposition step, and it was not possible to obtain sufficient electromagnetic conversion characteristics when formed into a magnetic tape.
Table 1 shows the characteristics.

[Comparative Examples 3 and 4] A laminated polyester film was prepared in the same manner as in Example 1 except that the type, average particle size, and amount of the inert particles B contained in the polyester layer B were as shown in Table 1. I got In the obtained film, it was satisfactory that the oligomer bleed out from the layer B was transferred to the opposite surface without any problem. However, in the case of Comparative Example 3, the degree of shape transfer to the opposite surface of the protrusion on the layer B side was small. When made into a magnetic tape, sufficient electromagnetic conversion characteristics could not be obtained. In the case of Comparative Example 4, the layer B was too flat to obtain a good winding property. Table 1 shows other characteristics and the characteristics of the ferromagnetic thin film-deposited magnetic tape using this film.

[0128]

[Table 1]

As is clear from Table 1, the laminated polyester film of the present invention has excellent heat resistance, so that one side is very flat, and there is little transfer of projections from the opposite side.
While exhibiting excellent electromagnetic conversion characteristics, the winding property is extremely good. On the other hand, those which do not satisfy the requirements of the present invention cannot simultaneously satisfy these characteristics.

[0130]

According to the present invention, it is possible to provide a laminated polyester film which is excellent in heat resistance and workability, and particularly useful for a metal thin film type magnetic recording medium having excellent electromagnetic conversion characteristics.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08L 67/00 C08L 67/00 101/00 101/00 G11B 5/64 G11B 5/64 5/733 5/733 5 / 735 5/735 (72) Inventor Tsuyoshi Ishida 3-37-19 Koyama, Sagamihara-shi, Kanagawa F-term in Sagamihara Research Center, Teijin Limited 4F100 AA19 AA19H AA20 AA20H AA36A AA36B AB01C AH10B AK25 AK25H AK41A AK41B AK41B AK41B AK52 AK52H AL06 AR00D BA02 BA03 BA04 BA06 BA10A BA10D BA13 CC00C DD07A DD07B DE01A DE01B DE01C DE01H DE04 DE04H EJ38 GB90 JG06D JJ03 JL01 JM02C 4J002 BC032 BG032 CC182 CF002 CF01 DE1 CF031 CF031 CF031 CF041 CF031 CF041 CF031 CF041 CF031 CF041 CF031 CF041 CF031 CF041 DG056 DJ006 DJ016 DJ036 EH057 EH077 FD012 FD016 5D006 CB01 CB05 CB08 EA03 FA04

Claims (15)

[Claims] 1. The diethylene glycol component is added in an amount of 0.1 to 0.1.
A polyester layer A containing 2.5% by weight, and a germanium element laminated on one side of the layer A, containing 1 to 50 ppm of germanium, and having a larger average particle size and a larger average particle size than the inert particles A in the layer A Inactive particles B of 50 to 1000 nm.
A laminated polyester film comprising a polyester layer B containing 001 to 1% by weight. 2. The laminated polyester film according to claim 1, wherein the ten-point average roughness (WRzB) of the surface of the polyester layer B is 30 to 300 nm. 3. The laminated polyester film according to claim 1, wherein the polyester layer B contains (partially saponified) ester wax comprising an aliphatic monocarboxylic acid having 8 or more carbon atoms and a polyhydric alcohol. 4. The surface roughness (WR) of the surface of the polyester layer A
The laminated polyester film according to claim 1, wherein aA) is from 0.1 to 4 nm. 5. The laminated polyester film according to claim 1, wherein the content of the germanium element in the polyester layer A is 0 to 10 ppm. 6. The laminated polyester film according to claim 1, wherein the polyester layer A contains substantially no particles. 7. The polyester layer A has an average particle size of 30 to 40.
The laminated polyester film according to claim 1, 4 or 5, comprising 0.001 to 0.2% by weight of 0 nm inert particles A. 8. The laminated polyester film according to claim 1, wherein a coating layer C is laminated on a surface of the polyester layer A which is not in contact with the layer B. 9. The coating layer C has an average particle size of 10 to 50 nm,
Inert particles C having a volume shape coefficient of 0.1 to π / 6
The laminated polyester film according to claim 8, which contains 30% by weight. 10. The laminated polyester film according to claim 1, wherein the thickness of the film is 2 μm or more and less than 8 μm. 11. The laminated polyester film according to claim 1, wherein the polyester in the layer A or the layer B is polyethylene terephthalate. 12. The polyester according to claim 1, wherein the polyester in Layer A or Layer B is polyethylene-2,6-naphthalate.
A laminated polyester film according to any one of the above. 13. The laminated polyester film according to claim 1, wherein the surface of the polyester layer A or the coating layer C is a surface on which a magnetic layer is provided. 14. The laminated polyester film according to claim 13, wherein the magnetic layer is a ferromagnetic metal thin film layer. 15. A magnetic recording medium using the laminated polyester film according to claim 13 or 14 as a support.