JPH0479368B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION The present invention relates to coated films. Specifically, the present invention relates to a polyester film for magnetic recording media, and more particularly to a polyester film for vapor-deposited video. [Prior art] Vapor-deposited video tape, in which a magnetic substance is vapor-deposited on the surface of a polyester film, is capable of extremely high-density magnetic recording, but because the thickness of the magnetic layer is very thin, the surface morphology of the base film used becomes the surface morphology of the deposited thin film after magnetic material deposition,
Therefore, if the surface roughness of the base film is rough, the electromagnetic conversion characteristics of the vapor-deposited video tape will be significantly deteriorated. Considering this electromagnetic conversion characteristic, a base film with a completely smooth mirror surface is preferable, but the deposited film formed on such a base film has extremely slippery properties because the deposited surface maintains its mirror surface. Unfortunately, unless a protective layer is provided on the vapor deposition surface, a large amount of scratches will occur in the tape forming process after the vapor deposition process, making it completely impractical. Furthermore, a serious problem in the actual use of vapor-deposited video tapes is the runnability of the vapor-deposited surface. In the case of conventional coated video tapes, which are made by mixing magnetic powder into an organic binder and coating it on a base film, it is possible to add a lubricant to the binder to improve the running properties of the magnetic surface. In the case of videotape,
The runnability of the deposited surface is generally disadvantageous unless a protective film layer is provided. Since it is difficult to uniformly provide a protective film layer on the vapor deposition surface, in the case of vapor deposition tapes without this protective film layer, it is necessary to improve the runnability of the vapor deposition surface, especially under harsh conditions when actually used. That is, there are drawbacks such as the inability to improve running performance under high temperature and high humidity conditions. [Object of the Invention] The object of the present invention is to provide a base film that can form a deposited film with excellent smoothness, scratch resistance, and runnability not only in normal environments but also under high temperature and high humidity conditions. There is a particular thing. [Configuration of the Invention] The present invention has the following configuration to achieve the above object. That is, a polyester film, a discontinuous film with a thickness of 500 Å or less mainly consisting of a water-soluble polymer and fine particles with a particle size of 30 to 500 Å closely adhered to at least one side of the polyester film, and a discontinuous film of the discontinuous film. The discontinuous film is made up of fine particles that are in close contact with the film surface of the discontinuous part, and protrusions are formed by the fine particles on the discontinuous film, and the height of the fine particles that are in close contact with the film surface of the discontinuous part of the discontinuous film is The thickness of the coating film is higher than the thickness of the discontinuous coating. The polyester film of the present invention is a polyester film formed by a well-known method, that is,
A film made by melting polyester and extruding it into a sheet or cylindrical shape and stretching it in at least one direction.The mechanical properties of the film include a normal balanced type, a uniaxially strengthened type, and a biaxially strengthened type. It is desirable that it be one of the more powerful types. In addition, it is desirable that the surface of the polyester film be smooth, and specifically, the roughness of the film surface is such that the cutoff value of the stylus surface roughness meter is 0.08 mm, and the Ra value is 0.015μ or less, more preferably 0.010. It is desirable that it be within the range of ~0.002μ. Note that the Ra value is calculated using an appropriate cut-off value from the cross-sectional curve obtained from a stylus surface roughness meter.
Arithmetic of the absolute value of the height (lowness) of the roughness curve from the center line (calculated by making the areas above and below the center line equal) in a roughness curve excluding waviness. (according to DIN 4768). The polyester forming the film may be of any type as long as it is mainly composed of linear polyester. For example, polyethylene terephthalate, polytetramethylene terephthalate,
Representative examples include poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalene dicarboxylate, and polyethylene-p-oxybenzoate. Further, the above polyester may be a homopolyester or a copolyester. In the case of copolyester, the components to be copolymerized are:
For example, diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylylene glycol, 1,
Diol components such as 4-cyclohexanedimethanol, adipic acid, sebacic acid, phthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 5
Examples include dicarboxylic acid components such as -sodium sulfoisophthalic acid, polyfunctional dicarboxylic acid components such as trimellitic acid and pyromellitic acid, and p-oxyethoxybenzoic acid. In the case of copolymerization, the amount of copolymerized components is 20 mol% or less. Furthermore, the above-mentioned polyester is mixed with at least one of an alkali metal salt derivative of sulfonic acid that is non-reactive with the polyester, a polyalkylene glycol that is substantially insoluble in the polyester, etc., to an extent not exceeding 5% by weight. It's okay. Furthermore, when the film is stretched, it may contain internal particles consisting of polymerization residues that cause protrusions on the film surface or inert particles added from the outside, and the content thereof is determined by When the polymer is biaxially stretched, it is sufficient that the thickness is 30 μm or less and the haze per sheet is 5% or less. The discontinuous film of the present invention is formed from a composition mainly consisting of a water-soluble polymer and fine particles, and preferably contains a silane coupling agent or a titanium coupling agent. Fine protrusions made of fine particles are formed on the discontinuous film. Further, the thickness of the discontinuous film of the present invention is 500 Å or less,
Preferably it is 50 to 300 Å. If the thickness exceeds 500 Å, the electromagnetic conversion characteristics of the deposited thin film, especially the S/N ratio, will deteriorate. The water-soluble polymer used in the present invention has a molecular weight of 10,000 to 2,000,000, preferably 100,000 to 1,000,000. When the molecular weight is less than 10,000, the film described below becomes soft, it becomes difficult to maintain the structure, and the durability deteriorates. If the molecular weight exceeds 2 million, the film becomes too hard and brittle, resulting in poor durability. As such water-soluble polymers, polyvinyl alcohol, gum tragacanth, gum arabic, casein, gelatin, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, water-soluble polyester ether copolymers, etc. can be used. The water-soluble polymer of the present invention is not a single component, but includes a water-soluble polymer for forming a discontinuous film and a water-soluble polymer that serves as an easily adhesive component that makes it difficult for fine particles present in the film to fall off from the film. A multi-component system is desirable. The fine particles of the discontinuous film forming component of the present invention are:
The size is 30 to 500 Å, preferably 50 to 400 Å, particularly preferably 50 to 95 Å. Here, the size refers to the maximum particle size of fine particles, and if the size is less than 30 Å, the runnability of the vapor-deposited thin film formed by vapor-depositing a magnetic material on this discontinuous film will not improve. Moreover, if the size exceeds 500 Å, the electromagnetic conversion characteristics of the magnetic surface deteriorate. The shape of the fine particles may be spherical, ellipsoidal, rectangular, cubic, or the like. In addition, the particle types include inorganic compound particles such as MgO, ZnO, MgCO ₃ , CaCO ₃ ,
CaSO ₄ , BaSO ₄ , Al ₂ O ₃ , SiO ₂ , TiO ₂ and Ca,
Acid salts such as Ba, Zn, and Mn can be used. Multiple types of fine particles may be used. Fine particles exist in the discontinuous film and on the film surface, and the number of particles present is 10 ⁴ to 10 ¹¹
It is necessary that the number of particles/mm ² is preferably 10 ⁵ to ^{10 10} pores/mm ² . The runnability of a deposited thin film obtained by depositing a magnetic material on a discontinuous film having a particle count of less than 10 ⁴ particles/mm ² or a diameter of less than 30 Å does not improve. The diameter and number of particles are determined by observation with an electron microscope. When the number of particles exceeds 10 ^{to 11} particles/ ^mm2 , the electromagnetic conversion characteristics of the magnetic surface, especially the S/N
The ratio worsens. Further, fine particles tend to fall off, which is not preferable. In the present invention, the fine particles closely attached to the film surface of the discontinuous portion of the discontinuous film are those with a diameter of 50 to 10,000 Å,
Preferably, the particles are 100 to 5000 Å, which is larger than the diameter of the fine particles on the surface of the discontinuous film described above.
It is desirable that the ratio is 2 or more, preferably 5 or more. The diameter refers to the maximum length of fine particles determined by observing the film of the present invention with an electron microscope. The shape of the fine particles is spherical, ellipsoidal, rectangular, cubic, etc. The height of the particles is such that 20% or more of the total number of particles, preferably 50% or more of the particles are higher than the discontinuous film, preferably 20~
A height of 500 Å is desirable. The number of particles is 10 ⁴ to 10 ⁸
It is desirable that the density is 10 ⁶ to 10 ⁸ pores/mm ² , preferably 10 6 to 10 8 pores/mm ² . If the number is less than 10 ⁴ pieces/mm ² , there is a tendency that the runnability of the vapor-deposited film surface formed by vapor-depositing a magnetic material on this surface does not improve. If the number exceeds ¹⁰⁸ pieces/ ^mm2 , the electromagnetic conversion characteristics of the magnetic surface, especially the S/N
Although organic compound particles are preferable as the particle type that tends to deteriorate the ratio, inorganic compound particles subjected to hydrophobic surface treatment may also be used. For example, they are fine particles made of polystyrene, polyethylene, polyamide, polyester, polyacrylic acid ester, polyepoxy resin, polyvinyl acetate, polyvinyl chloride, polysodium acrylate, polyvinyl methyl ether, fluorine resin, and the like. Plural types of fine particles may be used. It is desirable that the height of the fine particles is higher than that of the discontinuous film, preferably 20 to 500 Å, more preferably 30 to 200 Å. If the height of the fine particles is low, these fine particles do not contribute to improving the runnability of the vapor deposited film surface provided on the surface on which the discontinuous film is formed. If it exceeds 500 Å, the electromagnetic conversion characteristics of the deposited film surface will deteriorate. That is, the S/N ratio becomes low and dropout increases. Silicone, a fluorine compound, or both may be included as a structural component of the film in order to improve the slipperiness and scratch resistance of the discontinuous film. The silicone that can be used has a molecular weight of 30,000 to 300,000, and is preferably used as a chain component. However, R ₁ : CH ₃ , C ₆ H ₅ , H R ₂ : CH ₃ , C ₆ H ₅ , H or a functional group (for example,
(epoxy group, amino group, hydroxyl group) n: 100 to 7000, is a silicone compound having an integer that satisfies the above molecular weight according to R ₁ and R ₂ , and has an epoxy group, amino group, hydroxyl group, or other functional group at the end. It has an end group. In the present invention, the silicone compound is not necessarily a homopolymer, but may be a copolymer or a mixture of several types of homopolymers. The molecular weight of silicone is preferably 30,000 to 300,000. When the molecular weight is less than 30,000, the film becomes too soft and the structure becomes easily deformed. on the other hand,
On the other hand, if it exceeds 300,000, the film becomes brittle. Usable fluorine-based compounds include fluorine-based surfactants, fluorine-containing hydrocarbon compounds, etc., but the atomic ratio is 10 to 60%, preferably 20%.
A fluorine content of ~50% is desirable. If the fluorine content is low, no slipping effect can be seen. In addition, in order to strengthen the bond between water-soluble polymers, silicones, fluorine compounds, or both, to strengthen the adhesive force between the film and the polyester film, and to strengthen the bond between the film and the fine particles in the film, discontinuous It is desirable to add a silane coupling agent to the particles present in the discontinuities in order to strengthen the adhesion between the coating components and the particles present in the discontinuities of the discontinuous coating and the polyester film. Silane coupling agents are organosilicon monomers that have two or more different reactive groups in their molecules; one of the reactive groups is a methoxy group, ethoxy group, silanol group, etc., and the other is a silane coupling agent. Examples of reactive groups include vinyl, epoxy, methacrylic, amino, and mercapto groups. The reactive group is selected to be one that bonds with the water-soluble polymer side chain, terminal group, and polyester.As a silane coupling agent, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-glycidoxy Propyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyl Triethoxysilane etc. can be applied. Water-soluble polymer [A] silicone or fluorine-based compound or mixture thereof [B], silane coupling agent [C], fine particles [D], and discontinuous parts of the discontinuous film as components of the discontinuous film The usage ratio of fine particles [E] present in is [A]:[B]:[C]:[D]:[E]=20:0~20
:0
〜20:1〜40:1〜40, (preferably 20:0〜
20:1~20:1~30:1~30). [B] may be used for the purpose of improving slip properties and scratch resistance. [C] is preferably used to improve the bonding strength between various components. If [B] exceeds the upper limit, the adhesion strength of the deposited film will be poor. If [C] exceeds the upper limit, the discontinuous film structure becomes too hard and the film becomes brittle, which is not preferable. When [C] is used, [D] and [E] are firmly bonded to the discontinuous film or film surface. The fine particles [D] are 10 ⁴ to 10 ¹¹ pieces per discontinuous film.
mm ² , [D]
If it is less than the above lower limit, the presence of the particles becomes sparse, and the runnability of the vapor deposition surface deteriorates. Exceeding the upper limit is not preferable since the fine particles fall off from the film more frequently and the electromagnetic characteristics deteriorate. The fine particles [E] mainly adhere to the film surface of the discontinuous part of the discontinuous film, but when [E] falls below the above lower limit, the number of adhering particles decreases, and the vapor deposition formed on the discontinuous film decreases. It no longer contributes to improving the runnability of the membrane surface. If the upper limit is exceeded, fine particles will be more likely to fall off the film surface. Further, the electromagnetic conversion characteristics are also deteriorated, which is not preferable. Hereinafter, the coated film of the present invention will be explained based on the drawings. Figure 1 shows a discontinuous film that partially covers the surface of a polyester film, a state in which fine protrusions are present on the discontinuous film due to fine particles existing within the film, and a state in which the film surface at the discontinuous part of the film is FIG. 3 is a plan view showing fine particles in close contact with each other. The situation can be seen by observing it with an electron microscope at a magnification of 10,000 times or more. FIG. 2 is a schematic cross-sectional view of the film of FIG. 1 with a discontinuous coating and fine particles adhered thereto. Indicates a state in which the height of the fine particles is higher than the height of the discontinuous film. In FIGS. 1 and 2, 1 is a polyester film, 2 is a discontinuous film, 3 is a fine particle in the discontinuous film, and 4 is a fine particle existing in a discontinuous portion of the discontinuous film. The height (thickness) of the discontinuous film of the present invention is indicated by h in FIG.
The average of the peaks and valleys in the surface roughness curve when measuring the surface film-formed surface using a 0.08mm lens at a vertical magnification of 500,000 times, excluding peaks due to fine particles present in discontinuities. This is the value measured by the height interval. The heights of fine particles are h _P1 , h P2 , h _P2 , and
This is indicated by h _P3 , and is the value measured as the difference between the peak and valley portions that are larger than h in the height direction.
Note that FIG. 3 schematically shows the actually measured curve. Roughness due to fine particles present in the discontinuous film is difficult to observe. The height of the discontinuous coating of the present invention is 500 Å or less, preferably 50 to 300 Å. If the height exceeds 500 Å, the electromagnetic characteristics of the videotape with the vapor-deposited film formed on its surface, especially the S/N ratio, will deteriorate. Tape characteristics were evaluated by repeatedly recording and playing back using a commercially available VHS VTR. The tape runnability was evaluated at normal temperature and humidity, and at high temperature and high humidity.
This was done by performing playback under these conditions and observing screen fluctuations due to disturbances in tape running.
The evaluation criteria are as follows. ○: The vehicle runs smoothly and there is no fluctuation in the playback screen. ×: The running becomes slow in some places, and the playback screen fluctuates. The scratch resistance was evaluated by observing scratches on the tape thin film after repeatedly running the tape 100 times under normal temperature and humidity conditions and high temperature and high humidity conditions.
The evaluation criteria are as follows. ◎: Almost no scratches are observed on the thin film surface of the tape. ○: A few very weak scratches are observed on the thin film surface of the tape. ×: Severe scratches occur on the thin film surface of the tape. Note that normal temperature and humidity is 25°C and 60% RH, and high temperature and high humidity is 50°C and 80% RH. For the S/N ratio, record a 50% white level signal at the optimum recording current for each tape, and measure the signal-to-noise ratio contained in the video demodulated signal during playback using a video noise meter, using a commercially available VHS standard tape as OdB. Comparative measurements were made. Dropout records a three-step wave signal on a magnetic recording tape at the optimum recording current, and the attenuation of the video head amplifier output during playback is 18 dB and the duration is
Dropouts of 20 μsec or more were measured using a dropout counter for 10 minutes, and the average per minute was taken. The S/N ratio dropout measurement was performed at room temperature and humidity. When a discontinuous film containing the fine particles of the coating film of the present invention has protrusions caused by the fine particles and a vapor deposited film is provided on the surface of the discontinuous portion of the discontinuous film on the side where the fine particles are closely attached, a magnetic head, a guide Although the contact area with the surface of the deposited film is extremely small, the distance between the ferromagnetic thin film surface and the magnetic head is kept very narrow, so the running properties of the deposited film surface are extremely good. Moreover, the electromagnetic conversion characteristics are excellent. Next, a method for manufacturing the film of the present invention will be explained. At least one side of a smooth polyester film stretched in one direction by a conventional method contains inorganic fine particles, organic compound fine particles, organic compound emulsion, or inorganic fine particles subjected to hydrophobic surface treatment, with a molecular weight of 10,000 or more. A coating solution containing a 2,000,000 ml water-soluble polymer aqueous solution, more preferably a silane coupling agent is applied, and after drying, stretching is carried out in the orthogonal direction, or after stretching in the orthogonal direction, the coating solution is further stretched in the above-mentioned one direction and then heat treated. do. By using inorganic fine particles that have good affinity with water-soluble polymers, fine particles can be made to exist in a discontinuous film, and are compatible with water-soluble polymers as organic fine particles or organic compounds in organic compound emulsion. By using inorganic fine particles that are not treated with a hydrophobic surface or that have been subjected to a hydrophobic surface treatment, a discontinuous film surface in which the fine particles are closely adhered to the discontinuous portions can be formed. Note that the water-soluble polymer solution here is preferably a two-component system. One component used is one that has adhesive properties that can particularly easily hold inorganic fine particles. More specifically, the polyester raw material described above is melt-extruded using a normal film-forming machine, cooled, and then uniaxially stretched 3 to 5 times to form a longitudinally stretched film.
Thereafter, in a step before preheating and stretching, a coating liquid containing a water-soluble polymer aqueous solution with a molecular weight of 10,000 to 2 million, containing fine inorganic compound particles, fine organic compound particles, or organic compound emulsion, preferably a silane coupling agent, is applied. , applied on at least one side by various coating methods. Silicone or fluorine compounds or mixtures thereof may be added to the coating liquid components. The coating amount of this coating liquid is preferably 3 to 1000 mg/m ² in terms of solid content per surface. Next, this longitudinally stretched film coated with the coating solution is stretched in the transverse direction, but in order to form a film completely before the transverse stretching, it is necessary to completely evaporate the moisture in the coating solution on the film surface to dryness. This is the stenter preheating part of the biaxial stretching machine, which is 5%/second to 100%/second.
Hot air temperature 100-150℃ to achieve moisture drying speed of seconds
by preheating. 90~ after preheating
Transversely stretch 2.5 to 4.5 times at a stretching temperature of 120°C. After drying is completed and the film is completely formed, the film surface contains fine particles due to lateral stretching, and the resulting discontinuous film has protrusions, and the fine particles adhere to the film surface at the discontinuous parts of the discontinuous film. be done. This contributes to film slippage. Furthermore, this horizontally stretched film is heat treated at 180 to 220℃ or
Heat treatment at 180-220℃ after re-stretching to ~1.8x
A film having at least one surface of a smooth polyester film on which a discontinuous film with a height of 500 Å or less containing protrusions is formed, in which fine particles are present in discontinuous portions. An axially stretched polyester film is obtained. The above explanation was about a single layer film, but
In the production of a composite film by coextrusion of the raw material described in the text and a film raw material to which fine particles are actively added, the technology described herein may be applied to the surface of a smooth film layer. [Effects] As described above, the present invention allows a discontinuous coating provided with protrusions made of microparticles mainly composed of a water-soluble polymer and microparticles to be brought into close contact with the surface of a polyester film. By closely adhering to the continuous portion, the running performance of the surface of the vapor deposited film formed on the film forming surface is dramatically improved. Moreover, since the height of this discontinuous film is 500 Å or less, the electromagnetic conversion characteristics of the vapor-deposited tape are not impaired. Further, since the height of the fine particles formed in the discontinuous portions of the discontinuous film is 500 Å or less higher than the height of the discontinuous film, dropout does not increase. Although the coated film of the present invention can be applied to various uses, it is preferably used as a base film for magnetic recording media, and more preferably as a base film for forming a ferromagnetic metal thin film. Next, an example of manufacturing a coated film of the present invention and an example of applying the film to a magnetic tape will be described based on Examples. Example 1 A substantially non-oriented, non-crystalline polyethylene terephthalate raw material containing as little internal particles as possible due to polymerization catalyst residue etc. was melt-extruded onto a rotating drum maintained at about 20°C, and then a 3.4 times larger machine was used. After that, using a metering bar coater, the following aqueous solution emulsion was applied at a solid content concentration of 20%.
mg/m ² coated on both sides. As an aqueous emulsion, methcellulose
0.20wt%, 0.15wt of ultrafine silica with average particle size of 200Å
% and polyacrylic acid ester emulsion (solid content concentration 40%) at a ratio of 0.10 wt%.
Drying, preheating, and stretching temperatures are 115℃ and moisture drying speed is
The rate was set at 15%/second. At a transverse stretching ratio of 3.4 times and a heat treatment temperature of 200°C, a discontinuous film with a height of 260 Å is formed on both sides, and microprotrusions with a diameter of 200 Å are formed in the discontinuous film, which is 50 Å higher than the height of the discontinuous film. A polyethylene terephthalate film having a thickness of 12 μm was obtained in which fine particles were adhered to the discontinuous portions of the discontinuous film at a rate of 4×10 ₆ particles/mm ² . A cobalt-nickel alloy thin film with a thickness of 1500 Å was formed on the surface of this polyester film by vacuum deposition. Subsequently, the film was cut into a predetermined width in the machine direction to obtain a magnetic tape. This characteristic is shown in Table 1. Example 2 In the production of the base film of Example 1, the ratio of 0.35 wt% of water-soluble polyester ether copolymer and 0.05% of silane coupling agent N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane in the aqueous emulsion used. Using the aqueous solution added in Example 1, the other conditions were the same as in Example 1, and the height was 270 mm, with fine particles on both sides and protrusions caused by them.
A discontinuous film with a height of 40 Å is formed, and fine particles with a height of 40 Å higher than the height of the discontinuous film are deposited at the discontinuous portion of 4×10 ⁶
A polyethylene terephthalate film with a thickness of 12 μm was obtained, which was adhered at a ratio of 1/mm ² . A magnetic tape was obtained in the same manner as in Example 1 using this base film. The tape properties are shown in Table 1. Example 3 In the production of the base film in Example 2, the polyacrylic acid ester emulsion in the aqueous emulsion used was replaced with a polyvinyl acetate emulsion (solid content 35%) containing 0.01 wt%. Otherwise, a discontinuous film with a height of 270 Å containing fine particles and protrusions was formed in the same manner as in Example 1.
Fine particles 50 Å higher than the height of the discontinuous film were adhered to the discontinuous portion at a rate of 3 × 10 ⁶ particles/mm ² to a thickness of 12 μm.
A polyethylene terephthalate film was obtained. Using this base film, a vapor-deposited magnetic tape was obtained in the same manner as in Example 1. The tape properties are shown in Table 1. Comparative Example 1 In the production of the base film of Example 1, an aqueous solution with a methyl cellulose aqueous solution concentration of 0.40% was used, and the other conditions were the same as in Example 1. A discontinuous film with a height of 600 Å containing fine particles and protrusions due to the presence of the methyl cellulose aqueous solution was used. A film is formed on both sides, and 4×10 ⁶ fine particles lower than the height of the discontinuous film are formed on the discontinuous part of the discontinuous film.
A polyethylene terephthalate film with a thickness of 12 μm was obtained, which was adhered at a ratio of 1/mm ² . A magnetic tape was obtained in the same manner as in Example 1 using this base film. The tape properties are shown in Table 1. Comparative Example 2 In manufacturing the base film of Example 1, ultrafine silica was not used, and the other things were the same, but the height was increased on both sides.
A polyethylene terephthalate film with a thickness of 12 μm was formed to form a 250 Å discontinuous film, and fine particles 60 Å higher than the height of the discontinuous film were adhered to the discontinuous portions of the discontinuous film at a rate of 4 × 10 ⁶ particles/mm ^{2 .} Obtained. A magnetic tape was obtained in the same manner as in Example 1 using this base film. The tape properties are shown in Table 1. Comparative Example 3 In the production of the base film of Example 1, ultrafine silica particles with a particle size of 1500 Å were used, and in the same manner as above, a discontinuous film with a height of 280 Å with protrusions of 1500 Å in diameter formed on both sides was formed. A polyethylene terephthalate film with a thickness of 12 .mu.m was obtained having a surface where fine particles having a height of 30 Å higher than the height of the discontinuous film were present at the discontinuous portions of the discontinuous film. Comparative Example 4 The base film was manufactured in the same manner as in Example 1 except that the concentration of the methylcellulose aqueous solution was 0.10% and the concentration of the polyacrylic acid ester emulsion was 1.5wt%. A discontinuous film with a height of 50 Å is formed on both sides, and fine particles 650 Å higher than the height of the discontinuous film are formed at the discontinuous part of the discontinuous film at 6 × 10 ⁷ particles/
A polyethylene terephthalate film with a thickness of 12 μm was obtained which was closely adhered at a ratio of mm ² . A magnetic tape was obtained in the same manner as in Example 1 using this base film. The tape properties are shown in Table 1. Comparative Example 5 In manufacturing the base film of Example 1, without using polyacrylic acid ester emulsion,
In the same way, a discontinuous film with a height of 260 Å containing fine particles and protrusions caused by the discontinuous film is formed on both sides, and the discontinuous film has a surface with no fine particles in close contact with the discontinuous part, and a thickness of 12 μm. A polyethylene terephthalate film was obtained. A magnetic tape was obtained in the same manner as in Example 1 using this base film. The tape properties are shown in Table 1. As is clear from the characteristic results in Table 1, the discontinuous film containing fine particles of the coated film of the present invention and the discontinuous portion of the discontinuous film have a vapor deposited film formed on the side to which the fine particles are adhered. Magnetic tape can be used at room temperature and humidity.
Even when used at high temperatures and high humidity, it has good running properties and scratch resistance, and is smooth and has excellent electromagnetic characteristics. 【table】

[Brief explanation of the drawing]

Figure 1 shows the coated film of the present invention, showing a discontinuous film that partially covers the surface of a polyester film, a state in which fine protrusions are present on the discontinuous film due to fine particles existing therein, and a state in which the film is coated. FIG. 3 is a plan view schematically showing fine particles closely adhered to the film surface of the discontinuous portion. FIG. 2 is a cross-sectional view schematically showing the cross section of FIG. 1, and shows the fine particles in and on the discontinuous film and the fine particles in close contact with the discontinuous portions of the discontinuous film. h in the figure is the film thickness. FIG. 3 is a stylus type surface roughness curve chart at a vertical magnification of 500,000 times for the discontinuous film surface formed according to the present invention. h is the height of the film, and h _P1 , h _P2 , and h _P3 are the heights of the fine particles present in the discontinuous parts of the discontinuous film. 1... Polyester film, 2... Discontinuous film, 3, 4... Fine particles.

Claims (1)

[Claims] 1. A polyester film, a water-soluble polymer closely adhered to at least one side of the film, and a particle size of 30~
It consists of a discontinuous film with a thickness of 500 Å or less mainly composed of 500 Å fine particles, and fine particles closely attached to the film surface of the discontinuous part of the discontinuous film, and there are no protrusions caused by the fine particles on the discontinuous film. is formed, and
A coated film in which the height of the fine particles closely adhered to the film surface of the discontinuous portion of the discontinuous coating is higher than the thickness of the discontinuous coating.