JPH0318573B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing a coated film. [Prior Art] Conventionally, vapor-deposited video tapes in which a magnetic substance is vapor-deposited on the surface of a polyester film have been used. However, since the thickness of the magnetic layer in this vapor-deposited videotape is extremely thin, the surface morphology of the base film used is the same as that of the ferromagnetic metal thin film (hereinafter simply referred to as the vapor-deposited film) that is vacuum-deposited. becomes. Therefore, if the surface roughness of the base film is rough, the electromagnetic conversion characteristics of the vapor-deposited videotape 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 maintains its mirror surface as it is, so
The slipperiness is very poor, and 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 method for producing 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. Our goal is to provide the following. [Structure of the Invention] The present invention provides polystyrene,
Hydrophobic organic compound particles made of at least one selected from the group consisting of polyethylene, polyamide, polyester, polyacrylic ester, polyepoxy resin, polyvinyl acetate, and polyvinyl chloride, or an inorganic compound subjected to hydrophobic surface treatment. A water-soluble polymer aqueous solution containing particles was applied at a solid content concentration of 3 to 1000 mg/m ² , and after drying, the film was stretched in a direction perpendicular to the stretching direction of the film, and if necessary, re-stretched. The present invention also features a method for producing a coated film that is subsequently subjected to heat treatment. By this method, a discontinuous film mainly composed of a water-soluble polymer with a height of 500 Å or less is adhered to at least one side of a polyester film, and fine particles are attached to the film surface of the discontinuous portion of the discontinuous film. A coated film can be produced in which the height of the fine particles is higher than the height of the discontinuous film. The unidirectionally stretched smooth polyester film of the present invention refers to a polyester film formed by a well-known method, that is, polyester is melted and extruded into a sheet or cylindrical shape, which is stretched in one direction (preferably 2 It is a film formed by stretching to more than double the original length. Note that the upper limit of the stretching ratio is about 6 times, although it is not particularly limited. In addition, the surface of polyester film is smooth, and specifically, the roughness of the film surface is 0.08 mm cutoff value on a stylus type surface roughness meter, and Ra value is 0.015μ.
Below, it is more preferably within the range of 0.010μ to 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 so that the areas above and below the center line are equal) in a roughness curve excluding waviness. Average (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, 1,4
- Diol components such as 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 addition, in the case of copolymerization,
The amount of components to be copolymerized 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 hydrophobic organic compound particles of the present invention are fine particles made of polystyrene, polyethylene, polyamide, polyester, polyacrylate, polyepoxy resin, polyvinyl acetate, or polyvinyl chloride. Furthermore, the inorganic compound particles subjected to hydrophobic surface treatment are those in which a hydrophobic organic group such as an alkyl group such as a methyl group or an ethyl group is bonded to the surface of an inorganic compound such as silica or calcium carbonate. The diameter of the particles of the present invention is 50 to 10,000 Å, preferably
It is 100-5000 Å. 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 water-soluble polymer of the present invention has a molecular weight of 10,000 to
2 million, preferably 100,000 to 1 million are used. 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. When 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, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, etc. can be used. In the present invention, a water-soluble polymer aqueous solution containing mainly the fine particles described above is applied to the uniaxially stretched polyester film described above at a solid content concentration of 3 to 1000 mg/m ² per one side of the film.
A coupling agent such as a lubricant such as silicone or a fluorine compound, a silane coupling agent, or a titanium coupling agent may be included in the coating liquid. The silicone that can be used has a molecular weight of 30,000 to 300,000, and preferably contains 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 (e.g.
epoxy group, amino group, hydroxyl group) n: 100 to 7000, and is a silicone compound having an integer that satisfies the above molecular weight with _R1 and _R2 , and has an epoxy group, amino group, hydroxyl group, or other functional terminal at the end. It has a 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 tends to change. On the other hand, if it exceeds 300,000 yen, 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. A high fluorine content improves the sliding effect. It is also desirable to add a silane coupling agent to the solution in order to strengthen the bonding properties of the coating liquid components after drying. 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-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyl Triethoxysilane etc. can be applied. Coating liquid components include water-soluble polymer [A], silicone or fluorine compound or mixture thereof [B], silane coupling agent [C], and hydrophobic organic compound particles, or hydrophobic surface treatment. The usage ratio (weight ratio) of the inorganic compound particles [D] is [A]: [B]: [C]: [D] = 20:0 to 20:
0-20:1-10, preferably [A]:[B]:
[C]:[D]=20:0-20:1-10:1-8. [B] and [C] improve slip properties and scratch resistance,
Although it is preferable to use it to improve the bonding strength between the components, it is not an essential component. If [B] exceeds the upper limit, the adhesion strength of the vapor deposited film formed on the coated surface of the coating 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] is firmly attached to the film surface. The fine particles mainly adhere to the film surface of the discontinuous part of the discontinuous film,
When [D] is less than the above lower limit, the number of adhesion decreases, and it does not contribute to improving the runnability of the vapor deposited film surface formed on this discontinuous film. 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. Apply this coating liquid to one side with a solid content concentration of 3 to 1000.
mg/m ² is applied, but if the application amount falls below the lower limit, a discontinuous film will no longer be formed. If the upper limit is exceeded, the height of the discontinuous film will exceed 500 Å.
The discontinuous film of the present invention has a net-like and/or dotted shape, and is shown by reference numeral 2 in FIG. It will be 90%. A uniaxially stretched film coated with a coating liquid is stretched in a direction perpendicular to the uniaxial direction, but in order to completely form a film before stretching, it is heated to 100 to 150°C with hot air, etc. to completely remove the moisture in the coating liquid on the film surface. The film is evaporated to dryness (preferably with a moisture content of 1% or less of the film-forming components), and then stretched 2.5 to 4.5 times at a stretching temperature of 90 to 120°C. Furthermore, this stretched film is heat treated at 180 to 220℃, or 1.1 to 1.8 times, and after re-stretching, it is heated to 180 to 220 degrees.
When heat treated at ℃, fine particles are present in discontinuities on the smooth surface of polyester film.
A biaxially stretched polyester film having at least one surface on which a discontinuous film of 500 Å or less is formed is obtained. In addition, since the surface of the particles is hydrophobic, they are closely attached to the discontinuous portions outside the discontinuous film made of the hydrophilic polymer. Hereinafter, a covered film produced by the production method of the present invention will be explained based on the drawings. FIG. 1 is a plan view showing a discontinuous film partially covering the surface of a polyester film and fine particles closely attached to the film surface at the discontinuous portion of the film. 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, and 3 is a fine particle. The height (thickness) of the discontinuous film produced by the manufacturing method of the present invention is indicated by h in Fig. 3, and the measurement of h, that is, the height, is performed using a stylus type surface roughness meter. The average height of peaks and valleys, excluding peaks caused by fine particles, in the surface roughness curve when measuring the surface film-formed surface using a cutoff value of 0.08 mm and a vertical magnification of 500,000 times. This is the measured value of the interval. The height of the fine particles is h _P1 in Figure 3,
They are indicated by h _P2 and h _P3 , and are the measured values of the difference between a peak and a valley that are larger than h in the height direction. Note that FIG. 3 schematically shows the actually measured curve. The height of the discontinuous film formed by the production method of the present invention is 500 Å or less, preferably 50 to 300 Å.
When the height exceeds 500 Å, the electromagnetic conversion characteristics of the videotape with a vapor-deposited film formed on this surface, especially the S/N
The ratio worsens. 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 sloping tape running.
The evaluation criteria are as follows. 〇: Running 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 40°C and 80% RH. The S/N ratio was determined by recording a 50% white level signal at the optimum recording current for each tape, and measuring the signal-to-noise ratio contained in the video demodulated signal during playback using a video noise meter, assuming a commercially available VHS standard tape as 0 dB. 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. S/N ratio and dropout measurements were carried out at room temperature and humidity. [Effects of the Invention] A coated film obtained by the production method of the present invention in which a discontinuous film mainly composed of a water-soluble polymer is adhered to the surface of the polyester film and fine particles are adhered to the discontinuous portions is as follows: Not only does it have excellent slipperiness and flatness, but when a vapor deposited film is provided on the side where the discontinuous coating of the coating film and the fine particles are in close contact, the magnetic head guide etc. Even though the contact area becomes 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, and the electromagnetic conversion characteristics are excellent. Are better. Note that since this discontinuous film has a height of 500 Å or less, it does not impair the electromagnetic conversion characteristics of the vapor-deposited tape. In addition, the height of the formed fine particles is 500 Å or less higher than the height of the discontinuous film, so there is no increase in dropout. The coated film obtained by the present invention can be applied to various uses, but it is preferably used as a base film for magnetic recording media, more preferably as a base film for forming a ferromagnetic metal thin film. [Example] Next, a method for manufacturing a coated film of the present invention and an example in which the film is applied 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 extruded using a 3.4 times larger machine. After that, the following aqueous solution emulsion was coated on both sides at a solid content concentration of 20 mg/m ² using a metering bar coater. Methyl cellulose as an aqueous emulsion
Polyacrylate emulsion (solid content concentration 40%) was prepared in a proportion of 0.20wt% and 0.10wt%. The drying, preheating, and stretching temperatures were 115°C, and the moisture drying rate was 15%/sec. 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 fine particles 50 Å higher than the height of the discontinuous film are formed in the discontinuous parts of the discontinuous film at 4 × 10 ⁶ particles/ Thickness 12μ closely adhered in the proportion of ^mm2
A polyethylene terephthalate film was obtained. 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, a silane coupling agent N was added to the aqueous emulsion used.
- Using an aqueous solution of β (aminoethyl)γ-aminopropylmethyldimethoxysilane added at a ratio of 0.05%, the other conditions were the same as in Example 1, and the height was 280 mm on both sides.
A discontinuous film with a height of 30 Å is formed, and fine particles 30 Å higher than the height of the discontinuous film are deposited at the discontinuity 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. Comparative Example 1 The base film of Example 1 was manufactured in the same manner as in Example 1, except that an aqueous solution with a methyl cellulose solution concentration of 0.50% was used and the solid content concentration was 1600 mg/m ^{2 2} Both sides were coated to a height of 700 Å A discontinuous film of 4 ^x 10
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 A polyethylene terephthalate film having a thickness of 12 μm was obtained in the same manner as in Example 1 except that the concentration of the methyl cellulose aqueous solution was 0.10% and the solid content was coated on both sides at a solid content of 2 mg/m ² . Application unevenness occurred, and no discontinuous film was formed. 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 magnetic tape with a vapor deposited film formed on the side where the discontinuous film of the coated film and the fine particles are in close contact with each other obtained by the present invention can be used at room temperature and normal humidity, at high temperature and high humidity. Also in the use of
Both have good running properties and scratch resistance, are smooth, and have excellent electromagnetic characteristics. 【table】

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing the surface of the coated film obtained by the production method of the present invention, where the fine particles and the discontinuous film are in close contact with each other. FIG. 2 is a sectional view schematically showing the cross section of FIG. 1, and shows a state in which fine particles and a discontinuous film are in close contact with each other. h in the figure is the film thickness. FIG. 3 is a stylus type surface roughness curve chart at a longitudinal magnification of 500,000 times for the discontinuous film surface formed by the manufacturing method of the present invention. h is the height of the film,
h _P1 , h _P2 , and h _P3 are the heights of the fine particles. 1: Polyester film, 2: Discontinuous film,
3: Fine particles.

Claims (1)

[Claims] 1 At least one member selected from the group consisting of polystyrene, polyethylene, polyamide, polyester, polyacrylic ester, polyepoxy resin, polyvinyl acetate, and polyvinyl chloride is applied to at least one side of the smooth polyester film after being stretched in one direction. A water-soluble polymer aqueous solution containing hydrophobic organic compound particles or inorganic compound particles subjected to hydrophobic surface treatment at a solid concentration of 3 to 3
A method for producing a coated film, which comprises applying 1000 mg/m ² , drying, stretching in a direction perpendicular to the stretching direction of the film, and further stretching if necessary, followed by heat treatment.