JPH0565929B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a magnetic recording film, in which one side has a magnetic layer and the other side has a magnetic layer to improve adhesion to the film substrate, and the other side has a magnetic layer to improve the adhesion to the film substrate. It is an object of the present invention to provide a magnetic recording film on which a coating film in which a lubricant is dispersed is formed in order to lower the coefficient and improve running properties. <Relationship with Prior Art> Generally, in magnetic recording tapes for audio, video, or computers, the surface of the base film is finished to be smooth in order to improve the magnetic recording sensitivity of the tape. However, such a smooth magnetic recording tape is not wound in an orderly manner during winding and unwinding, and tends to wind randomly. When such a magnetic tape is used, running properties deteriorate due to tension fluctuations, the output fluctuates, and the tape is easily deformed and damaged. On the other hand, in response to improvements in the performance of magnetic recording, efforts are being made to increase the amount of magnetic powder packed. However, when the packing density of the magnetic powder is increased, the adhesion of the magnetic layer to the base film tends to deteriorate and the strength of the coating film tends to decrease. <Objective of the Invention> In view of the above circumstances, an object of the present invention is to provide a magnetic recording film that has good running properties and extremely good adhesion of the magnetic layer to the base film. <Structure of the Invention> The present invention provides residues of a mixed dicarboxylic acid in which 0.5 to 15 mol% of the dicarboxylic acid component (A) is a dicarboxylic acid containing a sulfonic acid metal group and a glycol residue on at least one side of a polyester film. Water-insoluble polyester copolymer as main component, (B) boiling point 60
~200℃ water-soluble organic compound and (C) water as main components, and in a weight ratio of (A)/(B)=100/20-5000, (B)/(C)=100/50-10000. A film is formed from an aqueous dispersion of the blended polyester resin, and a lubricant is dispersed in a paint containing a sulfonic acid metal base-containing polyester resin as at least one component on one side of the coated film. This is a magnetic recording film on which a coating film is formed, and the inventors have discovered that such a film has excellent adhesion to the magnetic layer and excellent running properties. The polyester copolymer (A) contained in the aqueous dispersion of the present invention is a mixture of 0.5 to 15 mol% of a dicarboxylic acid containing a sulfonic acid metal base and 85 to 99.5 mol% of a dicarboxylic acid containing no sulfonic acid metal base. It is a substantially water-insoluble polyester copolymer obtained by reacting dicarboxylic acid with a polyol component. Substantially water-insoluble means that even if the polyester copolymer is stirred in hot water at 80°C, the polyester copolymer will not dissipate in the hot water. The weight loss of the polyester copolymer after being stirred in 80°C hot water for 24 hours is 5% by weight or less. Examples of the above-mentioned dicarboxylic acids containing sulfonic acid metal groups include metals such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and 5[4-sulfophenoxy]isophthalic acid. salt was given,
Particularly preferred are 5-sodium sulfoisophthalic acid and sodium sulfoterephthalic acid. These sulfonic acid metal base-containing dicarboxylic acid components are 0.5 to 15 mol% of the total dicarboxylic acid components.
The content is preferably 2.0 to 10 mol%. 15
If it exceeds mol%, the dispersibility in water will improve, but the water resistance of the polyester copolymer will decrease significantly.
Moreover, if it is less than 0.5 mol%, the dispersibility in water will be significantly reduced. The dispersibility of the polyester copolymer in water varies depending on the copolymer composition, the type and blending ratio of the water-soluble organic compound, etc., but the above dicarboxylic acid containing a sulfonic acid metal group can be used as long as it does not impair the dispersibility in water. , a small amount is preferred. As the dicarboxylic acid that does not contain a sulfonic acid metal base, aromatic, alicyclic, and aliphatic dicarboxylic acids can be used. Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid,
Examples include 2,6-naphthalene dicarboxylic acid. It is preferable that these aromatic dicarboxylic acids account for 40 mol% or more of the total dicarboxylic acid components, and if it is less than 40 mol%, the mechanical strength and water resistance of the polyester copolymer will decrease. Aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid,
1,3-cyclohexanedicarboxylic acid, 1,4-
Examples include cyclohexanedicarboxylic acid.
When these non-aromatic dicarboxylic acid components are added,
Although adhesive performance may be improved in some cases, it generally reduces the mechanical strength and water resistance of the polyester copolymer. The polyol component to be reacted with the above mixed dicarboxylic acid is an aliphatic glycol having 2 to 8 carbon atoms or an alicyclic glycol having 6 to 12 carbon atoms, and specifically, ethylene glycol, 1,2-
Propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol These include methanol, P-xylylene glycol, diethylene glycol, triethylene glycol, and the like. Examples of polyethers include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Also, P
- An oxycarboxylic acid component such as oxyethoxybenzoic acid may be copolymerized. Polyester copolymers are obtained by conventional melt polycondensation. In other words, there is a direct esterification method in which the above dicarboxylic acid component and glycol component are directly reacted, water is distilled off and esterified, and then polycondensation is performed, or the dimethyl ester of the above dicarboxylic acid component and the glycol component are reacted to form methyl alcohol. It can be obtained by a transesterification method, etc., which involves distilling off, transesterifying, and then polycondensing it. In addition, solution polycondensation, interfacial polycondensation, etc. may also be used, and the polyester copolymer of the present invention is not limited by the polycondensation method. During melt polycondensation, antioxidants, slip agents,
Inorganic fine particles, antistatic agents, etc. can be added as appropriate. In order to obtain the aqueous dispersion of the polyester copolymer described above, it is necessary to disperse it in water together with a water-soluble organic compound. For example, the above polyester copolymer and a water-soluble organic compound are mixed in advance at 50 to 200°C, and water is added to this mixture and dispersed by stirring, or conversely, the mixture is added to water and dispersed by stirring. method, or by coexisting a polyester copolymer, a water-soluble organic compound, and water.
There is a method of stirring at 120℃. The above-mentioned water-soluble organic compound is an organic compound having a solubility in water of 20 g or more at 20°C, and specifically includes aliphatic and alicyclic alcohols, ethers, esters, and ketone compounds, such as methanol, ethanol, Monohydric alcohols such as isopropanol and n-butanol, glycols such as ethylene glycol and propylene glycol,
These include glycol derivatives such as methyl cellosolve, ethyl cellosolve, and n-butyl cellosolve, ethers such as dioxane and tetrahydrofuran, esters such as ethyl acetate, and ketones such as methyl ethyl ketone. These water-soluble organic compounds can be used alone or in combination of two or more. Among the above compounds, butyl cellosolve and ethyl cellosolve are preferred in terms of dispersibility in water and coatability on films. The weight ratio of the above (A) polyester copolymer, (B) water-soluble organic compound, and (C) water is (A)/(B)=100/20~5000 (B)/(C)=100/ It is important to satisfy the range of 50 to 10,000. When the amount of the water-soluble organic compound is small relative to the polyester copolymer and the ratio (A)/(B) exceeds 100/20, the dispersibility of the aqueous dispersion decreases. In this case, dispersibility can be assisted by adding a surfactant, but if the amount of surfactant is too large, adhesiveness and water resistance will decrease. Conversely, if (A)/(B) is less than 100/5000, or
If (B)/(C) exceeds 100/50, the amount of water-soluble organic compounds in the aqueous dispersion increases, and after applying the above polyester resin aqueous dispersion to a melt-extruded unstretched film or a uniaxially stretched film, There is a risk of explosion due to the solvent during so-called in-line coating, which necessitates taking explosion-proof measures, and furthermore, it is necessary to consider recovery of the compound as it causes environmental pollution and increases costs. (B)/(C) is 100/10000
If the amount is less than 1, the surface tension of the aqueous dispersion increases, the wettability to the film decreases, and coating spots are likely to occur. In this case, the wettability can be improved by adding a surfactant, but if the amount of the surfactant is too large, the adhesiveness and water resistance decrease as described above. The above aqueous dispersion includes slip agents, antistatic agents,
Anti-blocking agents, cross-linking agents, etc. may be added. The polyester film to which the aqueous dispersion of polyester copolymer (A) is applied is a melt-extruded unstretched film, a uniaxially stretched film, or a biaxially stretched film. After coating an aqueous resin dispersion, it is stretched to form a biaxially stretched film. The amount of the aqueous dispersion applied to the polyester film is preferably 0.01 to 5 g/m ² of the polyester copolymer based on the film after biaxial stretching. If the coating amount is less than 0.01 g/m ² , the adhesiveness of the magnetic material layer provided on the polyester copolymer layer will be insufficient. If the coating amount exceeds 5 g/m ² , the mechanical strength of the polyester film decreases, and the amount of copolymerized polyester resin in the recovered and recycled film increases, resulting in deterioration of the mechanical strength and heat resistance of the recycled film. If the polyester film is subjected to corona discharge treatment before applying the aqueous dispersion of the polyester resin mentioned above, the applicability of the aqueous dispersion will be improved and the adhesive strength between the polyester film and the polyester copolymer coating will be improved. This is a preferred embodiment because it improves the performance. In addition, by subjecting the polyester copolymer layer to corona discharge treatment, corona discharge treatment under a nitrogen atmosphere, ultraviolet irradiation treatment, etc., the wettability and adhesion of the polyester copolymer layer with the magnetic layer and the coating film containing the lubricant dispersed therein can be improved. can be improved. On the polyester copolymer layer coating film,
The lubricants to be dispersed in the coating film formed on one side of the coated film include tungsten disulfide, molybdenum disulfide, boron nitride, SiO ₂ , CaCO ₃ ,
Al ₂ O ₃ , Fe ₂ O ₃ , TiO ₂ , MgO, ZnO, CaO,
Examples include SnO ₂ and BaSO ₄ . Among the above, SiO ₂ ,
CaCO ₃ , TiO ₂ and BaSO ₄ are preferred, and CaCO ₃ and BaSO ₄ are particularly preferred. When using these lubricants, particular attention must be paid to their size and hardness. Average particle size as size: 0.02~
It is preferably 0.5μ, particularly preferably 0.02 to 0.5μ. The hardness is preferably 2.5 or higher on the Mohs scale. The amount of these lubricants used is based on the weight ratio of the binder.
0.1-4.0 preferably 0.1-2.5, particularly preferably 0.5
~1.5. As the binder used simultaneously with these, for example, a thermoplastic resin, a thermosetting resin, a reactive resin, or a mixture thereof is used, but as a dicarboxylic acid component of the copolymerized polyester resin (D) used in the present invention, is aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalic acid, P-oxybenzoic acid, P-
(Hydroxyethoxy) Aromatic oxycarboxylic acids such as benzoic acid, aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecane dicarboxylic acid, etc., but aromatic dicarboxylic acid components and aliphatic dicarboxylic acids It is desirable that the molar ratio with the aromatic dicarboxylic acid component is from 50/50 to 100/0, and that at least 30 mol % of the aromatic dicarboxylic acid component is terephthalic acid. Small amounts of tri- and tetracarboxylic acid components such as trimellitic acid, trimesic acid, and pyromellitic acid may be used in combination. The glycol components to be reacted with the dicarboxylic acid include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,
6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, ethylene oxide adduct and propylene oxide adduct of bisphenol A , ethylene oxide adducts and propylene oxide adducts of hydrogenated bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. Small amounts of tri- and tetraols such as trimethylolethane, trimethylolpropane, glycerin, and pentaerythritol may be used in combination. Further, an oxycarboxylic acid component such as P-oxyethoxybenzoic acid may be copolymerized. The dicarboxylic acid component containing a sulfonic acid metal base that characterizes the copolymerized polyester resin (D) includes 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 2-sodium sulfoterephthalic acid, and 2-potassium sulfoterephthalic acid. The copolymerization amount of dicarboxylic acid components containing these sulfonic acid metal bases is 0.3 to 7.0 mol%, preferably 1.0% by mole based on the total dicarboxylic acid components.
~5.0 mol%. If the copolymerization amount is less than 0.3, the performance improvement will not be sufficient;
If the amount of copolymerization exceeds the above, the solvent solubility of the copolymerized polyester will be poor and it will be impractical. These copolyester resins have the effect of particularly improving the dispersibility of lubricants and the adhesion to polyester films. The amount of copolymerized polyester resin used is 2% by weight or more of the total binder, but
Preferably it is 10% by weight or more. In addition, vinyl chloride is added as a binder.
Vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer , acrylic ester-styrene copolymer, methacrylic ester-acrylonitrile copolymer, methacrylic ester-vinylidene chloride copolymer, methacrylic ester-styrene copolymer, urethane elastomer, polyvinyl fluoride, chloride Vinylidene-acrylonitrile copolymer, butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose resin (cellulose acetate butyrate, nitrocellulose, cellulose diacetate, cellulose propionate, etc.), styrene-butadiene copolymer, chloro vinyl ether-acrylic ester copolymer,
Examples include amino resins, phenolic resins, epoxy resins, polyurethanes, curable resins, urea resins, melamine resins, alkyd resins, acrylic reaction resins, polyisocyanates, and polyamines. If the copolymerized polyester resin (D) has a low softening point, depending on the application, there is a risk that it will soften due to the intense heat between it and the head, or that it will block when wrapped with tape. In such a case,
It is desirable to mix a compound which is compatible with the copolyester resin within a range that does not impair the dispersibility of the lubricant particles and which reacts and crosslinks. The mixing amount is generally 2 to 100 parts by weight per 100 parts by weight of the copolyester resin. Examples of such compounds include epoxy resins, isocyanate compounds, and melamine resins.
Among these, isocyanate compounds are particularly preferred. Using the terminal groups of the copolymerized polyester resins (A) and (D) thus obtained, bifunctional isocyanate compounds such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenyl A polymer subjected to a chain extension reaction with methane diisocyanate, xylene diisocyanate, or isophorone diisocyanate can be used. This method combines two types of copolymerized polyester resins,
You can make use of your characteristics. That is, this is a preferred embodiment because the introduction of urethane groups can improve the adhesion to polyester films, improve the solvent solubility of the copolymerized polyester resin, and improve the water resistance of the coating film. Various films have been proposed as the base film for magnetic recording media, but polyester film is superior in terms of mechanical properties, chemical resistance, heat resistance, etc. Among them, polyethylene terephthalate film is superior in terms of various properties. It is excellent. The surface roughness of the undercoat coated side and the anti-coat side of this polyester film is very important for reducing noise and preventing signal dropouts in the production of magnetic recording media, and the centerline average roughness ( _RA ) (Surfcom
Using a 300A type surface roughness meter (manufactured by Tokyo Seimitsu), measure the needle diameter.
1μm, weight 0.07g, measurement reference length 0.8mm, cutoff
(measured under the condition of 0.08mm) is preferably 0.05μm or less,
If it exceeds 0.05 μm, noise and signal dropout will occur, causing problems in use. In addition, the surface roughness of the coating film in which the lubricant is dispersed is very important in order to reduce noise and prevent signal loss when used as a magnetic tape, since the unevenness of the coating surface is transferred to the magnetic layer. The roughness (R _A ) (measured using a Surfcom 300A surface roughness meter (manufactured by Tokyo Seimitsu) with a needle diameter of 1 μm, a load of 0.07 g, a measurement reference length of 0.8 mm, and a cutoff of 0.08 mm) is preferably 0.03 μm or less. , if it exceeds 0.03 μm, noise and signal loss will occur, causing problems in use. In the magnetic recording film of the present invention, additives such as carbon black powder and graphite can be added to the coating film in which a lubricant is dispersed for antistatic purposes. <Effects of the Invention> As described above, when the film obtained by the present invention is used for magnetic recording, it has excellent adhesion to the magnetic layer, has a low coefficient of friction during running, and has excellent running durability. There is an effect. <Examples> The present invention will be specifically explained below using examples. In the examples, parts simply indicate parts by weight. In the adhesion test (peel-back method), an adhesive tape was pasted on the surface of the magnetic layer, the adhesive tape was uniformly adhered to the entire surface, and then the state was observed when it was instantly peeled off. The portion where the magnetic layer remains accounts for 95% or more of the total area ◎,
50 to 95% is indicated by ◯, 10 to 50% is indicated by △, and 10% or less is indicated by ×. The driving durability test was 100 on a VHS video deck.
The coefficient of dynamic friction (at a running speed of 3.3 m/sec) on the coating film side in which the lubricant was dispersed was measured for the tape that was run repeatedly and the virgin tape that was not run. The reduced viscosity ηsp/C (dl/g) was measured at 30°C by dissolving 0.10 g of polyester resin in 25 ml of a mixed solvent of phenol/tetrachloroethane (weight ratio 6/4). The softening point was measured according to JIS2351. In the examples, magnetic tape was formed on the undercoat layer as follows. Magnetic paint Co-Fe (3:7) alloy fine particles (average diameter
0.02μm) 300 parts Acrylonitrile/Butyl acrylate/Dihydroxyl methacrylate (=90/190/20) 30 parts Coconut oil 50% modified alkyd resin 35 parts Silicone oil 2 parts Butyl acetate 700 parts Put the above paint into a ball mill. Coronate L as a polyisocyanate compound after kneading for 12 hours
(manufactured by Nippon Polyurethane Co., Ltd.) was added and dispersed under high-speed shearing for 1 hour to obtain a magnetic paint. This paint was filtered through a filter with an average pore size of 3 microns to form an undercoat layer on a polyethylene terephthalate film with a thickness of 25 microns, and the thickness after drying was 3 μm.
It was applied and dried by heating. The magnetic tape thus obtained was calendered and slit into 1/2 inch width to obtain a videotape. Example 1 (1) Production of aqueous dispersion of polyester copolymer (A) 117 parts (49 mol%) of dimethyl terephthalate, 117 parts (49 mol%) of dimethyl isophthalate, 103 parts (50 mol%) of ethylene glycol, 58 parts (50 mol%) of diethylene glycol, 0.08 part of zinc acetate, and 0.08 part of antimony trioxide were heated to 40 to 220°C in a reaction vessel and transesterified for 3 hours, and then 9 parts of 5-sodium sulfoisophthalic acid ( 2 mol%) was added, the esterification reaction was carried out at 220 to 260°C for 1 hour, and the polycondensation reaction was further carried out for 2 hours under reduced pressure (10 to 0.2 mmHg), with an average molecular weight of 18,000 and a softening point of 140.
A polyester copolymer was obtained. 300 parts of this polyester copolymer and 140 parts of n-butyl cellosolve were stirred in a container at 150 to 170°C for about 3 hours to obtain a homogeneous and viscous melt.
After about 1 hour, a homogeneous pale white aqueous dispersion with a solid content concentration of 30% was obtained.
4,500 parts of ethyl alcohol was added to obtain a coating solution with a solid content concentration of 3%. (2) Manufacture of coated film Polyethylene terephthalate is melt extruded at 280 to 300℃ and cooled with a cooling roll at 15℃ to a thickness of 130℃.
A micron unstretched film was obtained, and this unstretched film was stretched 3.5 times in the longitudinal direction between a pair of rolls at different circumferential speeds at 85°C, and this uniaxially stretched film was subjected to corona discharge treatment, and then transferred to the corona discharge treated surface. The above coating solution was applied using an air knife method, dried with hot air at 70°C, then stretched 3.5 times in the transverse direction at 98°C with a tenter, further heat-set at 200-210°C, and biaxially stretched to a thickness of 12 microns. A coated polyester film was obtained. (Undercoating process: in-line) (3) Production of copolyester resin (D) for coating film formation containing lubricant dispersion 175 parts of dimethyl terephthalate,
Add 78 parts of dimethyl isophthalate, 161 parts of ethylene glycol, 145 parts of neopentyl glycol, 14.8 parts of dimethyl 5-sodium sulfoisophthalate, 0.17 parts of zinc acetate, 0.02 parts of sodium acetate and 0.16 parts of antimony trioxide and heat at 140 to 220°C. The transesterification reaction was carried out for 3 hours. Then sebacic acid
After adding 131 parts and reacting at 210 to 250°C for 1 hour, the reaction system was depressurized to 1 to 5 mmHg over 60 minutes.
Further, a polycondensation reaction was carried out at 250°C under reduced pressure of 0.1 to 0.3 mmHg for 60 minutes. The copolymerized polyester resin (D) thus obtained was pale yellow and transparent with ηsp/C=0.63 and a softening point of 113°C. According to NMR (nuclear magnetic resonance) analysis, the composition was as follows: Terephthalic acid 45 mol% Isophthalic acid 20 Sebacic acid 32.5 5-Sodium sulfoisophthalic acid 2.5 Ethylene glycol 50 Neopentyl glycol 50 (4) Contains lubricant dispersed. Coating film formation method Copolymerized polyester resin (D) 50 parts PVC-vinyl acetate copolymer (manufactured by Denki Kagaku Kogyo Co., Ltd.) 5 parts Nitrocellulose 10 parts Polyisocyanate (Coronate L: manufactured by Nippon Polyurethane Co., Ltd.) 15 parts CaCO ₃ (average particle size 0.05 μm) was kneaded and dispersed and applied onto the 12 micron thick biaxially stretched coating polyester film obtained in (2) above, and the thickness of the coating after drying was 1. I set it to microns. Example 2 In the composition of the primer in Example 1
A magnetic recording film was obtained in the same manner as in Example 1 except that a portion of the DEG was replaced with PEG and the binder composition in the lubricant-dispersed coating film composition was changed. Examples 3 to 4 In Example 3, a magnetic recording film was prepared in the same manner as in Example 2, except that the binder composition in the lubricant-dispersed coating film composition was changed, and in Example 4, the type of lubricant was changed to SiO ₂ . I got the film. Comparative Example 1 A magnetic recording film was obtained in the same manner as in Example 1 except that the undercoating step was not performed. Comparative Example 2 A magnetic recording film was obtained in the same manner as in Example 1 except that the lubricant-dispersed coating film was not formed in Example 1. Comparative Example 3 Example 1 except that 5-sodium sulfoisophthalic acid in the primer was changed to 20 mol% in Example 1.
A magnetic recording film was obtained in the same manner as above. Comparative Example 4 A magnetic recording film was obtained in the same manner as in Example 2 except that the copolyester resin was not added to the lubricant-dispersed coating film. Comparative Example 5 Demonstrated the properties of an untreated polyester film that did not form either an undercoat or a lubricant dispersion coating. From Table 1, the present invention has better adhesion of the magnetic layer to the base film than the comparative example.
It can be seen that the running performance is also extremely good.

[Table] Comparative Example 6 In Example 2, methyl methacrylate/ethyl acrylate/hydroxyacrylate copolymer (molar ratio
Example 2 was repeated except that 65/30/5) was used. Comparative Example 7 In Example 2, terephthalic acid/isophthalic acid/adipic acid/ethylene glycol/diethylene glycol copolymer (molar ratio 40/40/20/30/70) was used instead of the resin component in the lubricant dispersion coating composition. Example 2 was repeated except that a polyurethane resin reacted with diphenylmethane diisocyanate was used. Comparative Example 8 In Example 2, phenoxy resin (PKHH,
Example 2 was carried out in the same manner as in Example 2 except that the product (trade name) was used. Comparative Example 9 In Example 2, nylon resin (Tresin,
Example 2 was carried out in the same manner as in Example 2, except that the product name (trade name) was used. The results of the characteristics of Comparative Examples 6 to 9 are shown in Table 2.

[Table] From the above, acrylic resin, polyurethane resin,
It can be seen that good effects cannot be obtained even when phenoxy resin or nylon resin is used as a resin for a lubricant-dispersed coating film.

Claims (1)

[Claims] 1. (A) on at least one side of the polyester film
A water-insoluble polyester copolymer whose main components are residues of mixed dicarboxylic acid and glycol, in which 0.5 to 15 mol% of the total dicarboxylic acid components are dicarboxylic acids containing sulfonic acid metal bases, (B) boiling point 60 to 200 ℃
The main components are a water-soluble organic compound and (C) water, and are blended in a weight ratio of (A)/(B) = 100/20 to 5000 and (B)/(C) = 100/50 to 10000. A coating film is formed from an aqueous dispersion of a polyester resin, and on one side of the coating film, a lubricant is dispersed in a coating material containing a polyester resin containing a sulfonic acid metal base as at least one component. A magnetic recording film made of a film. 2 The polyester resin containing sulfonic acid metal base of the paint used for the coating film in which the lubricant is dispersed is (D)
A patent claim which is a polyester resin whose main components are residues of a mixed dicarboxylic acid and a residue of glycol, which has a reduced viscosity of 0.1 or more and 0.3 to 7.0 mol% of the total dicarboxylic acid component is a dicarboxylic acid containing a sulfonic acid metal group. A magnetic recording film according to item 1. 3. The magnetic recording film according to claim 1 or 2, wherein the polyester film is a film made of polyethylene terephthalate. 4. The magnetic recording film according to claims 1 to 3, wherein the centerline average roughness (R _A ) of the surface of the polyester film is 0.05 μm or less. 5. The magnetic recording film according to claims 1 to 4, wherein the centerline average roughness ( _RA ) of the surface of the coating film in which the lubricant is dispersed is 0.03 μm or less. 6. The magnetic recording film according to claims 1 to 5, wherein the water-insoluble polyester copolymer (A) is a polymer chain-extended with a diisocyanate compound. 7. The magnetic recording film according to claims 1 to 6, wherein the polyester resin (D) is a polymer chain-extended with a diisocyanate compound.