JP3144580B2 - Polymer base material for metal thin film magnetic recording medium and metal thin film magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal thin film type magnetic recording medium and a polymer substrate used for the same , and more particularly, to rust prevention, slipperiness, smoothness, adhesion, transparency and abrasion resistance. Metal thin-film magnetic recording media with excellent runnability and durability .
And a polymer substrate used for the same.

[0002]

2. Description of the Related Art In recent years, as magnetic recording media have become smaller and lighter or have been recorded for a longer time, it has become necessary to record information at a higher density. For high-density recording, it is necessary to shorten the recording wavelength and reduce the spacing loss between the magnetic recording medium and the magnetic head as much as possible. With this, the surface of the magnetic recording medium becomes smoother. It is desirable. Above all, a metal thin film type magnetic recording medium obtained by forming a ferromagnetic thin film on a base film by a method such as vacuum deposition, sputtering, ion plating, etc., has a larger thickness of a magnetic layer than a conventional coating type magnetic recording medium. Can be reduced to about 1/30 or less, so that the thickness loss due to the shortening of the recording wavelength can be reduced, and the surface of the magnetic recording medium can be made smoother by using a smooth base film. This is extremely effective for high-density recording, for example, because spacing loss between magnetic heads can be reduced.

Research and development of such a ferromagnetic metal thin film type magnetic recording medium have been actively conducted, but a ferromagnetic metal thin film made of cobalt, nickel or a mixture thereof has a drawback that it is easily rusted. When the ferromagnetic metal thin film is rusted, the electrical and magnetic properties of the magnetic recording medium are significantly reduced. Regarding the rust prevention of ferromagnetic metal thin films, for example, JP-A-53-88704 discloses a method of applying a surfactant to a metal magnetic material layer, and JP-A-57-186230 discloses a silane coupling method on a magnetic layer surface. JP-A-57-191831 discloses a method of providing a coating made of a hydrolyzate of the agent, and a method of attaching a perfluoroalkylcarboxylate to the surface of a magnetic layer. It is also known to use a material for trapping corrosive gas in a tape cassette case.

[0004]

However, the above-mentioned conventional metal thin film type magnetic recording medium has the following problems. That is, JP-A-53-88704 and JP-A-5-88704
The method disclosed in, for example, Japanese Patent Application Laid-Open No. 7-191831 in which a surfactant is applied to the surface of the metal magnetic layer has a problem in the durability of the rust preventive effect, and as described in JP-A-57-186230. The method of providing a film made of a hydrolyzate of a silane coupling agent on the surface has a problem in durability of the film layer. Also, the method using a material for trapping corrosive gas in the tape cassette case has no effect on the rust prevention of the magnetic layer due to water absorption.

The present invention solves these drawbacks of the prior art, and has both excellent rust-preventing effect and durability, and at the same time, has improved slipperiness, smoothness, easy adhesion, abrasion resistance, running properties, and electromagnetic conversion characteristics. And excellent metal thin film type magnetic recording medium and its use
It is an object of the present invention to provide a polymer base material .

[0006]

Means for Solving the Problems] metal thin film type magnetic recording medium for a polymeric substrate of the present invention along this purpose, the polymer of the magnetic recording medium formed by providing a magnetic layer of a metal thin film on a polymer substrate
In the base material , the polymer base material is coated with a coating material comprising a phosphate group-containing polymer on the base material , and the coating material is used for one time.
× 10 ⁵ / mm ² or more surface protrusions formed
It is characterized by the following .

[0007] The polymer substrate referred to in the present invention may be, for example, various films such as polyester, polyamide, polyimide, and polyamideimide, but is not limited thereto. However, a polyester film is particularly preferred in view of the balance between price and performance.

[0008] Polyester as used herein is a generic term for polymers having an ester bond as a main bonding chain of a main chain.
Particularly preferred polyesters, polyethylene terephthalate - DOO, polyethylene 2,6-naphthalene - DOO, polybutylene terephthalate - DOO, polyethylene alpha, beta-bis (2-chlorophenoxy) ethane 4, 4 '- dicarboxylate - DOO etc. Of these, polyethylene terephthalate is most preferable in consideration of quality, economy and the like. Therefore, hereinafter, polyethylene terephthalate (hereinafter abbreviated as PET) will be described as a typical example of polyester.

PET is 80 mol% or more, preferably 9 mol% or more.
At least 5 mol% of ethylene phthalate is used as a repeating unit, but other dicarboxylic acid components and diol components may be used within this limited amount range. Also known additives in this PET, for example, heat stabilizers, oxidation stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents, A nucleating agent may be blended. The intrinsic viscosity (measured in orthochlorophenol at 25 ° C.) of the above PET film is 0.4
0 to 1.20 dl / g, preferably 0.50 to 0.80 d
Those in the range of 1 / g are suitable for the content of the present invention. The polyester film in the present invention is preferably biaxially oriented in view of mechanical and thermal properties. For example, the biaxially oriented PET film when the above PET is used as the polyester is the same as the unstretched P film.
ET sheet or film in longitudinal and width direction,
Each of them is made by stretching about 2.5 to 5 times,
It indicates a biaxially oriented pattern in wide-angle X-ray diffraction.
The thickness of the PET film is not particularly limited, but is usually preferably in the range of 1 to 500 μm,
The range of μm is more preferred.

The phosphoric acid group-containing polymer referred to in the present invention is not particularly limited as long as it is a polymer having a phosphoric acid group in the molecule. 1
Compounds having a phosphoric acid group or a phosphoric acid ester group ethylenically unsaturated bond in the molecule, for example, acid phosphooxyethyl methacrylate, 3-chloro-2-acidphosphoxypropyl methacrylate, acid phosphoroxypropyl methacrylate Rate, acid phosphoxyethyl acrylate, methacryloyloxyethyl phosphate monoethanolamine half salt, methacryloyloxyethyl acid phosphate dimethylaminoethyl methacrylate half salt, methacryloyloxyethyl Acid phosphate diethylaminoethyl methacrylate half salt, acid phosphooxypolyoxyethylene glycol monomethacrylate, acid phosphooxypolypropylene glycol monomethacrylate, and the like. It can be. Among these compounds, a halogen-containing compound and a long-chain compound are particularly preferred for more remarkably exhibiting the effects of the present invention. One or more of the above compounds are copolymerized with another compound having an ethylenically unsaturated bond.

Other compounds having an ethylenically unsaturated bond copolymerized with the compound having an ethylenically unsaturated bond with a phosphate group or a phosphoric ester group include alkyl acrylate and alkyl methacrylate. (As the alkyl group, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, lauryl, stearyl, cyclohexyl, phenyl, benzyl Group)
And a compound having a functional group such as a reactive functional group, a self-crosslinkable functional group, and a hydrophilic group. As the functional group, a carboxyl group and / or a salt thereof, an acid anhydride group, a sulfonic acid group and / or a salt thereof,
Examples thereof include an amide group or an alkylated amide group, an amino group (including a substituted amino group) or an alkylated amino group and / or a salt thereof, a hydroxyl group, an epoxy group, and the like.

Examples of the compound having a carboxyl group and / or a salt thereof or an acid anhydride group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, alkali metal salts of these carboxylic acids, and ammonium. Salts and anhydrides.

Examples of the compound having a sulfonic acid group and / or a salt thereof include vinyl sulfonic acid, styrene sulfonic acid, alkali metal salts and ammonium salts thereof. Examples of the compound having an amide group or an alkylated amide group include acrylamide, methacrylamide, N-methylmethacrylamide, methylolated acrylamide, methylolated methacrylamide, ureidovinyl ether, and β-ureidoisobutyl. And vinyl ether and ureidoethyl acrylate.

Examples of the compound having an amino group or an alkylated amino group and / or a salt thereof include diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropyl vinyl ether,
2-aminobutylvinyl ether, dimethylaminoethyl methacrylate, dimethylaminovinyl ether, and their amino groups methylated, alkyl halides, dimethyl sulfate, sultone, etc. And the like. Examples of the compound having a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxymethacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, and β-hydroxypropyl methacrylate.
-Hydroxyvinyl ether, 5-hydroxypentylvinyl ether, 6-hydroxyhexylvinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol −
Lumonomethacrylate and the like. Examples of the compound having an epoxy group include glycidyl acrylate and glycidyl methacrylate. Further, in addition to the above, the following compounds may be used in combination. That is, acrylonitrile, methacrylonitrile, styrenes, butyl vinyl ether, maleic acid mono- or dialkyl ester, itaconic acid mono- or dialkyl ester,
Examples thereof include methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine, vinyl pyrrolidone, and vinyl trisalkoxysilane, but are not limited thereto. These compounds may be copolymerized singly, or two or more of them may be copolymerized.

The phosphoric acid group-containing polymer of the present invention can be dissolved or dispersed in water, and such a copolymer is copolymerized with a monomer having a hydrophilic group (eg, acrylic acid, methacrylic acid, acrylamide). It can be made by polymerization. For example, a compound having an ethylenically unsaturated bond with a phosphoric acid group or a phosphoric ester group, methyl methacrylate, butyl acrylate, and acrylic acid are charged into isopropyl alcohol, and an appropriate amount of a polymerization initiator (for example, benzoyl peroxide) is added. ), And the polymerization proceeds under heating to form a quaternary copolymer. Next, ammonia water is added to ammonium the carboxyl group of acrylic acid. Then, alcohol can be obtained by removing the alcohol at a temperature lower than the boiling point of water and higher than the boiling point of isopropyl alcohol while adding water. Of course, the present invention is not limited to this method, and any method can be adopted.

The compound (a) having a phosphoric acid group or a phosphoric ester group and an ethylenically unsaturated bond and the compound (b) having another ethylenically unsaturated bond are copolymerized at an arbitrary ratio. (A) / (b) is in a weight ratio of 3/97 to 99/1, preferably 5/95 to 95/5, and more preferably 10/90 to exhibit the effect of
It is desirably 85/15. The average particle size of the phosphate group-containing polymer is 0.01 to 1 μmφ, preferably 0.01 to 1 μm.
Those having a uniform particle size distribution in the range of 0.5 μmφ are more preferable in terms of the smoothness of the projections.

Further, the phosphate group-containing polymer of the present invention may be blended with another polymer at an arbitrary ratio and applied to a polymer substrate. Other polymers are not particularly limited, but a cross-linkable polymer, especially a self-cross-linkable acrylic copolymer is preferred from the viewpoint of rust prevention effect, projection forming ability, slipperiness, transparency, abrasion resistance and the like. Used. In the present invention, the main feature is that the above aqueous coating solution is applied, dried, stretched in at least one direction, and then subjected to high-temperature heat treatment. Also,
Other substances such as a surfactant may be appropriately added as long as the effects of the present invention are not impaired.

In the present invention, such protrusions are provided on at least one surface of the polyester film. When provided on both surfaces, the description of the protrusions without nuclei described below applies to at least one of them. is there. The most common cause of rust on the cobalt / nickel magnetic layer as a ferromagnetic thin film metal for magnetic recording media is:
The formation of cobalt hydroxide due to moisture and oxygen gas is considered. The rust-prevention mechanism of these magnetic layers of the phosphate group-containing polymer of the present invention has not been sufficiently elucidated, but the phosphate group is chelated. It is interpreted that cobalt hydroxide is hardly generated because it acts as an agent and inhibits ionization of metals such as cobalt.

In the present invention, the acrylic resin which may be blended with the phosphate group-containing polymer at an arbitrary ratio includes a functional group-containing vinyl polymerizable monomer, a hydrocarbon vinyl polymerizable monomer, and a hydrocarbon non-polymerizable monomer. A copolymer compound such as a conjugated divinyl polymerizable monomer may be mentioned. In the present invention, a copolymer of a functional group-containing vinyl polymerizable monomer is preferably used.

The functional group-containing vinyl polymerizable monomers include:
For example, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-methylolacrylamide, N-
Butoxymethyl acrylamide, diacetone acrylamide, methylol diacetone acrylamide, 2-
Hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 3-
Chloro-2-hydroxypropyl methacrylate and the like can be mentioned, and are selected from these, but are not particularly limited. The water-dispersible self-crosslinkable acrylic copolymer has an average particle size of 0.01 to 1 μmφ, preferably 0.0 to 1 μmφ.
1 to 0.5 μmφ, more preferably 0.01 to 0.1
Those having a uniform particle size distribution in the range of μmφ are more preferable in terms of the smoothness of the projections. Further, from the viewpoint of abrasion resistance and the like, the projections of the present invention preferably do not contain inorganic particles, organic particles, inorganic colloids, and the like, but may be added in a small amount as long as the properties of the film of the present invention are not impaired. No problem. In that case, the amount of particles added is
It is preferably 10 parts by weight or less, more preferably 5 parts by weight or less with respect to 0 parts by weight. If the effect of the present invention is not impaired, methylcellulose is added to the self-crosslinkable acrylic copolymer in order to improve the flatness and lubricity of the projections.
Cellulose-based polymers such as ethyl cellulose and ethyl cellulose may be added. The addition amount is 5 per solid content of acrylic resin.
The range is preferably 30% to 30%, more preferably 10% to 20%.
If the added amount of cellulose exceeds 30%, the smoothness of the projections is undesirably deteriorated. On the other hand, when the addition amount is 5
% Is not preferable because the effect of improving smoothness and lubricity is not sufficient.

In the present invention, in order not to impair the smoothness of the projections, the morphology of the particles, etc., it is preferable to form the projections using only a phosphoric acid group-containing polymer and a self-crosslinking polymer. If not, the protrusions may contain a cross-linking agent in order to further improve adhesion and mechanical strength. The cross-linking agent referred to in the present invention is a nucleus having a three-dimensional network structure, which undergoes a cross-linking reaction with a functional group present in an acrylic copolymer, for example, a hydroxyl group, a carboxyl group, a glycidyl group, or an amide group. There is no particular limitation as long as it is a cross-linking agent for forming projections without,
Representative examples include methylolated or alkylated urea-based, melamine-based, acrylamide-based, polyamide-based resins, and epoxy compounds, isocyanate compounds, and aziridine compounds. Of these, methylolated melamine and isocyanate compounds are preferred in terms of adhesion to the base film, mechanical strength, and the like. These crosslinking agents may be used alone or in combination of two or more in some cases. The amount of the cross-linking agent to be added is appropriately selected depending on the type of the cross-linking agent.
0.01 to 50 parts by weight, preferably 0.1 to 50 parts by weight,
-30 parts by weight are more preferred. If the addition amount is less than 0.01 part by weight, the crosslinking effect is low, and if it exceeds 50 parts by weight, the adhesion of the projections is reduced, and the coatability is further deteriorated, making it difficult to form a uniform layer. A crosslinking catalyst may be used in combination with the crosslinking agent. Known catalysts such as salts, inorganic substances, organic substances, acid substances, and alkaline substances can be used as the crosslinking catalyst. The amount of the crosslinking catalyst to be added is 100
0.001 to 10 parts by weight with respect to parts by weight, preferably,
0.1 to 5 parts by weight. The coating agent to which the crosslinking agent is added is cross-linked by heating, ultraviolet rays, electron beams or the like after being applied to the base film, but a method by heating is generally used.

The projections in the present invention are made of a granular acrylic copolymer formed on the surface of the base polyester film, and the crosslinkable acrylic copolymer adheres to the base polyester film by heat melting or heat softening. Is formed by bonding with a base polyester film by adhesive force or the like. The polyester film as the base film constituting the film of the present invention may be uniaxially oriented, but is desirably biaxially oriented in terms of mechanical strength, dimensional stability, rigidity and the like. Although the thickness of the polyester film is not particularly limited, it is 1 to 500.
μm is preferable, and the range of 3 to 80 μm is more preferable.
Excellent handling properties in practical use as a base film. The surface roughness (Ra) and optical haze of the polyester film are not particularly limited, but the surface roughness (Ra) is not more than 0.02 μm, preferably 0.01 μm.
m or less. The protrusions constituting the film of the present invention have a thickness of 0.001 to 0.5 μm including the protrusions.
m is preferable, and the range of 0.005 to 0.25 μm is more preferable. When the lamination thickness is less than 0.001, not only uniform lamination is difficult but also lubricious projections are difficult to obtain. 0.5μ
If the number exceeds m, the projections have a film-forming property and it is difficult to form the projections.

Further, an epoxy compound as an adhesion promoter for the base polyester film or the magnetic layer,
A reactive compound such as an aziridine compound or a vinyl compound or a silane coupling agent may be contained. Further, if necessary, known additives in an amount that does not impair the effects of the present invention, for example, a coating improver, an antistatic agent, an antioxidant, an ultraviolet absorber, a rust inhibitor, a dye, an antifoaming agent, A thickener or the like may be included. Further, the number of surface projections per unit area needs to be 1 × 10 ⁵ / mm ² or more, preferably 1 × 10 ⁶ / mm ² or more, more preferably 1 × 10 ⁷ / mm ² or more. It is. When the value is more than this value, when a ferromagnetic thin film is formed, the lubricity on the formed surface is sufficient, and the electromagnetic conversion characteristics are further improved.
Further, the film of the present invention, after the protrusions are oriented in one direction,
Further, it is preferable that the orientation is strengthened by stretching in the same direction (re-lateral stretching) and then heat-treated.
It is desirable because the protrusions can be made more uniform and finer by the heat treatment.

Next, a method for manufacturing the magnetic recording medium of the present invention will be described, but the present invention is not limited thereto. First, after sufficiently drying the polyester pellets polymerized by a conventional method, a known extruder, preferably a compression ratio of 3.
The melt is extruded in a sheet form from a slit die at a temperature not lower than the temperature at which the pellets are melted and not higher than the temperature at which the polymer is decomposed, and cooled and solidified to form an undrawn sheet. . At this time, the intrinsic viscosity of the unstretched sheet is desirably 0.5 or more from the viewpoint of film properties. Next, the unstretched sheet is heated at 70 to 120 ° C for 2.0 to 5.0.
On a double-stretched film, a coating material prepared from the above composition in a predetermined amount is applied, and the coating film is dried to form a predetermined coating layer. Stretch. Further, if necessary, the film may be re-laterally stretched. Further, the biaxially oriented film is heat-treated at 150 to 250 ° C. for 1 to 60 seconds while giving 0 to 10% relaxation. The coating method is not particularly limited, and an extrusion laminating method or a melt coating method may be used. However, a gravure coating of a water-dispersed coating material is possible because a thin film can be coated at a high speed. It is preferable to apply a known method such as a coating method, a reverse coating method, a kiss coating method, a die coating method, and a metaling bar coating method. At this time, by applying a known surface treatment such as a corona discharge treatment in air or other various atmospheres as necessary before coating on the film, not only the coating properties are improved, but also the protrusions are formed. It can be formed more firmly on the film surface. The concentration of the coating material and the conditions for drying the coating film are not particularly limited, but the drying conditions for the coating film are preferably set within a range that does not adversely affect the properties of the polyester film. In order to obtain the projections of the present invention, the coating amount is 0.00
03-0.05 g / m ² , preferably 0.0015-0.
026 g / m ² , more preferably 0.003 to 0.00
A range of 7 g / m ² (all dry) is desirable. In the coating amount is 0.0003 g / m ² or less can not be imparted to less sufficient lubricity number projections, projections now have film-forming properties in the 0.05 g / m ² or more, the formation of projections Is not preferable because it becomes difficult. As described above, the laminated polyester of the present invention can be produced, and a ferromagnetic thin film type magnetic recording medium can be produced by providing a ferromagnetic thin film layer on the projection forming surface of the laminated polyester.

Here, the ferromagnetic thin film refers to a ferromagnetic metal such as iron, cobalt, nickel or Co-N
i, Fe-Co, Fe-Ni, Fe-Rh, Fe-C
u, Fe-Au, Co-Cu, Co-Au, Co-Y,
Co-La, Co-Pr, Co-Gd, Co-Sn, C
o-Pt, Ni-Cu, Fe-Co-Nd, Mn-B
A magnetic alloy such as i, Mn-Sn, Mn-Al is formed on a film by a vacuum deposition method, an ion plating method, a sputtering method, an ion beam deposition method, an electrolytic deposition method, an electrolytic plating method, or the like. . As the ferromagnetic thin film applied to the magnetic recording medium of the present invention, any of the methods manufactured by any of the methods described above can be used, of course, but the deposition direction is inclined in the longitudinal direction (90 ° to 30 °).
The a width direction as it is not tilted, O ² as the atmosphere
Alternatively, a material obtained by vapor deposition at 1 × 10 ⁻⁴ Torr while introducing O ² and Ar is preferably used. The thickness of the ferromagnetic thin film is usually 0.01 to 1 μm, preferably 0.05 to 0.
3 μm is used.

[0026]

According to the metal thin film type magnetic recording medium of the present invention, the following excellent effects can be obtained. First, since a coating agent composed of a phosphate group-containing polymer was applied on the polymer base material, the rust-preventing ability of the magnetic material layer of the metal thin film provided thereon could be greatly improved, and the magnetic material with excellent rust-preventing effect It can be a recording medium.

Further, since the projections can be formed on the polymer base material by the coating material itself, a metal thin film type magnetic recording medium excellent in lubricity, abrasion resistance, running properties and electromagnetic conversion characteristics can be obtained. .

[Measurement Method and Evaluation Method] The method for measuring characteristics and the method for evaluating effects in the present invention are as follows. (1) Rust prevention After coating and drying and heat-treating the coating composition of the present invention on a PET substrate, a metal material composition of Co / Ni = 80/20 was added while introducing oxygen at a rate of 0.2 L / min. Oblique deposition was performed to a thickness of 2 μm. After spin-coating a rust preventive on the surface of the magnetic layer of the obtained sample, the sample was heated at 60 ° C. and 90% R
H, and the saturation magnetization of the magnetic layer was measured by V.I. S. MAGNETMETER (Model B
HV-3,5) and XY plotter (Model F-42)
CP). The decay rate was calculated from the saturation magnetization over time. The occurrence of pitting on the surface of the magnetic layer was observed and evaluated with a microscope. The evaluation criteria are as shown in Table 1.

[0029]

[Table 1]

(2) Coating Layer Thickness Using a transmission electron microscope model HU-12 manufactured by Hitachi, Ltd., an ultra-thin section of the laminated film is observed to determine the thickness.

(3) Surface roughness (Ra) According to JIS-B-0601, using a stylus type surface roughness meter BE-3E manufactured by Kosaka Laboratory Co., Ltd., cut-off 0.0
The average surface roughness Ra (μm) was measured at 25 mm and a measurement length of 4 mm.

(4) Slipperiness (static friction coefficient μs, dynamic friction coefficient μk) The coefficient of friction between films is ASTM-D-1894.
The coefficient of static friction μs was measured in accordance with Example No. 63. Generally, the range in which the lubricity is excellent is 1.6 or less in μs, preferably 1.2 or less. The dynamic friction coefficient μk between the film and the metal post is measured using a dynamic friction coefficient device (TBT-300, manufactured by Yokohama System Research Institute) at 25 ° C. and 50% relative humidity in a coating surface or a ferromagnetic thin film forming surface. SUS420J with outer diameter 8mmφ, surface roughness 0.2S
Contact at a winding angle of 180 ° to 3.3 cm / s
After moving at the speed of ec, the tension is controlled so that the entrance tension T1 becomes 25 g, and the dynamic friction coefficient μk is calculated from the value (g) of the exit tension T2 by the following equation. μk = (2.303 / π) log (T2 / T1) = 0.733 log (T2 / T1)

(5) Easy adhesion Bell jar type high vacuum evaporation apparatus (E made by Nippon Vacuum Engineering Co., Ltd.)
(BH-6 type) and a commercial cellophane tape manufactured by Nichiban Co., Ltd. was stuck to the aluminum deposition surface at a degree of vacuum of about 1 × 10 ⁻⁵ mmHg, and a load of about 5 kg was applied using a hand roller. After the pressure bonding, evaluation was made on the aluminum remaining adhesion surface after forcible peeling in the 180 ° direction. Evaluation criteria are:
The remaining deposited area of the aluminum vapor-deposited film layer was rated as good (○) when it was 90% or more, poor (％) when 75 to 90%, and poor (x) when less than 75%. The larger the remaining adhesion area, the better the adhesiveness.

(6) Number of granular projections, SEM (scanning electron microscope, manufactured by Akashi Seisakusho Co., Ltd., DS
-130 type), magnification 10,000 to 30,000 times, angle 80
The photograph was taken with ゜ to count the number of granular projections, and the number of projections per piece / mm ^{2 was} calculated by area conversion. Also,
Non-contact three-dimensional fine shape measuring device ET manufactured by Kosaka Laboratory Co., Ltd.
The projection height, average roughness and the like were measured using a -30HK type.

(7) Thickness of Magnetic Layer In the case of a magnetic layer formed by vacuum evaporation, sputtering, or the like. Fluorescent X-ray microscopic part thickness meter STF-15 manufactured by Daini Seikosha
6 was measured.

(8) Runnability Coefficient of dynamic friction μ between the film and the metal post in the above item (4)
In the same manner as in k, the initial μk of the base material after running 300 times repeatedly is measured. Next, in a magnetic recording medium in which a lubricant is not applied to the surface after the formation of the ferromagnetic thin film, 5
In a magnetic recording medium coated with a lubricant on the surface after the formation of the ferromagnetic thin film after the repetition of 0 times, the μk value after the repetition of 300 times is smaller than the value increased by 25% of the initial μk value (running). Good), and the others were judged as (poor runnability).

(9) Electromagnetic conversion characteristics When the output signal when reproducing the sample magnetic recording medium is viewed in one screen, a signal having a strong output signal and a flat signal waveform (good) is regarded as an output signal. Were weak or the signal waveform was deformed, it was judged as (defective).

(10) Abrasion resistance The laminated polyester film is 25 to 30 cm long and 1 width wide.
/ 2 inch, when the laser blade is run at an angle of 90 ° with respect to the coating layer surface, at a depth of 0.5 mm, with a load of 500 g / 0.5 inch and a speed of 6.7 m / sec. The width in the depth direction of the shaving powder adhering to the laser blade was determined by microphotographing (× 160). The width of the shaved powder in the depth direction was 3 μm or less (○), 3 to 5 μm was (△), and 5 μm or more was (×). It goes without saying that the smaller the adhesion depth of the shaving powder, the better the shaving property.

(11) Haze of solution of chip In 20 ml of a known polyethylene terephthalate solvent,
3 g of the chip was dissolved and placed in a 20 mm-thick quartz cell, and the solution haze was measured.

[0040]

EXAMPLE 1 does not contain as much as possible inside the particles and inert particles based on the prepared polymerization catalyst residue査等by a conventional method, the solution haze of 0.8% polyethylene terephthalate phthalates - homopolymer chips (intrinsic viscosity bets = 0.62, melting point: 259 ° C)
It dried under reduced pressure (3 mmHg) at 0 degreeC for 2 hours. 28
The mixture was supplied to an extruder having a screw having a compression ratio of 3.8 at 0 ° C., filtered through a 10 μm-cut metal sintering filter, melt-extruded from a T-type die, and subjected to electrostatic application at a surface temperature of 20 ° C. Around the cooling drum to cool and solidify,
After forming an unstretched film, the obtained film was stretched 3.5 times in the longitudinal direction by roll stretching at 90 ° C., and the surface was subjected to corona discharge treatment. The treated surface was methyl methacrylate / butyl acrylate. -Acrylic acid / 3 chloro-2-acid phosphooxypropyl methacrylate (90/1
(0/15/15 weight ratio) quaternary copolymer aqueous solution (A) and water-dispersible acrylic copolymer comprising methyl methacrylate / ethyl acrylate / acrylic acid / N-methyl acrylamide (Japan) (Made by Carbide Industrial Co., Ltd.)
(B) was used as a 0.5% by weight aqueous coating composition having a solid content ratio of (A) / (B) of 20/80.

After applying this coating material to one surface of the uniaxially stretched film by a metalling bar coating method, the coated layer is stretched 3.6 times in the horizontal direction at 100 ° C. while drying, and then 2 times.
After 5% re-stretching in the transverse direction at 00 ° C., heat treatment was performed at 225 ° C. for 5 seconds while relaxing 2% in the transverse direction.
g / m ² (dry) was laminated to obtain a laminated polyester film having a thickness of 10 μm. Table 2 shows the properties of the laminated polyester film. Next, a Co-Ni alloy (Ni 20% by weight) was obliquely deposited on the film to a thickness of 200 nm by an electron beam evaporation method. A perfluoropolyalkyl ether metal salt in which trichlorotrifluoroethane is dispersed is applied at a solid content of about 30 mg / m ^{2 on} the vapor deposition surface of the vapor deposition film, and slit to a 1/2 inch width to form a magnetic tape. Obtained. Table 3 shows the results of evaluating the magnetic tape characteristics. The magnetic tape was heated at 60 ° C and 90 ° C.
The degree of rust of the magnetic layer when left in an atmosphere of% RH was evaluated by observing the degree of attenuation of saturation magnetization and the degree of occurrence of pitting on the metal surface of the magnetic layer using a microscope. The results are shown in Table 3.

Example 2 A laminated polyester film was obtained in the same manner as in Example 1 except that (A) / (B) was changed to 80/20. Next, after oblique deposition by the same method as in Example 1,
A magnetic tape was obtained. The properties of the laminated polyester film and the magnetic tape are shown in Tables 2 and 3. Table 2 and Table 3
As can be seen, when the laminated polyester film is within the range of the present invention, it is found that a magnetic recording medium having good rust prevention, running durability and electromagnetic conversion properties can be obtained.

Example 3 Based on Example 1, 3 chloro 2-acid phosphooxypropyl methacrylate, which is the coating agent (A) component of Example 1, was used.
A laminated polyester film and a magnetic tape were prepared in exactly the same manner except that 2-acid phosphooxyethyl methacrylate was used instead of the polyester. Table 2 shows the characteristics of both.
And Table 3.

Comparative Example 1 On the basis of Example 1, methyl methacrylate / butyl acrylate / acrylic acid / 3 chloro 2-acid phosphooxypropyl methacrylate (90/10/15/15)
(Weight ratio) without using any quaternary copolymer aqueous solution (A).
Water-dispersible acrylic copolymer consisting of methyl methacrylate / ethyl acrylate / acrylic acid / N-methyl acrylamide (manufactured by Nippon Carbide Industry Co., Ltd.)
(B) alone was used to prepare a coating of 0.5% by weight and applied to a substrate to obtain a laminated polyester film. Similarly, Co / Ni
Magnetic tape was prepared by oblique deposition and evaluated. The results are shown in Tables 2 and 3, but the magnetic layer was easily rusted because no phosphate group-containing compound was used.

Comparative Example 2 A homopolymer chip of polyethylene terephthalate having an intrinsic viscosity of 0.65 dl / g and a melting point of 262 ° C. manufactured by a conventional method was used as a main extruder, and a particle size of 0.4 was obtained from a sub-extruder.
intrinsic viscosity 0.62 containing 0.5% wet silica of 0.5 μm
dl / g, polyethylene terephthalate chips having a melting point of 260 ° C. are supplied, respectively, and the outer two layers containing inorganic particles are formed by a base-top short tube composite system in which three flows join in a short tube. Was extruded in a sheet form with a layer containing no particles at the center in a laminated state, wound around a cooling drum and solidified rapidly to form an undrawn three-layered layer. The film is stretched 3.5 times in the longitudinal direction at 95 ° C. between the rolls, then stretched 3.5 times in the width direction at 105 ° C. in the tenter, and further heat-treated at 235 ° C. for 10 seconds in the same tenter. Then both surfaces are 0.
A three-layer laminated film having a thickness of 2 μm and a total thickness of 10 μm was obtained. Since the three-layer laminated film was not coated with the coating liquid of the present invention, as shown in Tables 2 and 3, the magnetic layer was inferior in the rust-preventive effect and in the adhesive property.

[0046]

[Table 2]

[0047]

[Table 3]

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-286415 (JP, A) JP-A-3-229726 (JP, A) JP-A-63-157313 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) C08J ^7/ 04-7/06 B32B 27/00-27/42 B29C 55/00-55/30 G11B 5/66

Claims (5)

(57) [Claims] 1. A polymer base material for a magnetic recording medium comprising a polymer base material provided with a magnetic layer of a metal thin film, wherein the polymer base material is formed by coating a phosphoric acid group-containing polymer on the base material. 1 × 10 ⁵ / mm ² or more by the coating agent
A polymer base material for a metal thin-film type magnetic recording medium, characterized by having surface projections formed thereon. 2. The method according to claim 1, wherein the phosphate group-containing polymer is phosphoric acid.
2. The polymer base material for a metal thin-film magnetic recording medium according to claim 1, comprising a copolymer obtained by polymerizing tomonomer and acrylic. 3. The polymer base material for a metal thin-film magnetic recording medium according to claim 1, wherein a coating material obtained by mixing an acrylic copolymer with the phosphoric acid group-containing polymer is applied. 4. The method according to claim 1, wherein the surface of the polymer substrate has projections formed thereon.
A metal thin film type magnetic recording medium provided with a thin magnetic layer . 5. The magnetic recording medium according to claim 4 , wherein the metal thin film is made of Co, Ni or a mixture thereof.