JP2002028554A - Coating method and coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating method capable of efficiently and simply coating a wide substrate and forming a coating film with uniform thickness and enhancing productivity. SOLUTION: In the coating method, a plurality of dies are arranged in parallel in opposed relation to a back roll for supporting a fed long support in the width direction of the support to form the coating layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method which is advantageous for coating a wide substrate.

[0002]

2. Description of the Related Art Conventionally, the production of recording materials such as photographic light-sensitive materials, heat-development recording materials, ablation recording materials, magnetic recording media, and the like, surface treatment of steel sheets, etc., are performed by coating a running support or a plate surface. Have been done.

[0003] As a method of applying a coating solution to a continuously running long support (also referred to as a web), dip coating, blade coating, air knife coating, wire bar coating, gravure coating, reverse coating, and the like. A method, a reverse roll coating method, an extrusion coating method, a slide coating method, a curtain coating method, and an extrusion coating method at a position not supported by a back roll or the like are known.

For example, JP-A-56-95363 and JP-A-50-142463 disclose single-layer coating by an extrusion coating method using a die coater.
No. 2390 and Japanese Patent Application Laid-Open No. 46-236 each disclose multi-layer coating, which are applied to a web supported by a back roll while keeping a coater head (also called a die) at a clearance of usually 1 mm or less. Is what you do. Also, U.S. Pat. No. 2,681,294 describes a method of applying a stable pressure by reducing the pressure on the upstream side.

In any of the coating methods, in order to obtain a coating layer having a uniform dry film thickness in the width direction of the web, special consideration is given to the dimensional accuracy of the coating apparatus and the coating is performed with care.

As a method for improving the coating thickness distribution in the width direction of the web, conventionally, the gap between the coater head and the support has been partially mechanically adjusted in the coating width direction. Also, recently, as disclosed in Japanese Patent Application Laid-Open No. Hei 8-215631, the gap adjusting mechanism is made movable in the width direction,
Method for enabling adjustment at an arbitrary position, Japanese Patent Laid-Open No. 10-32
No. 8600, a method in which a metal support is conveyed at a high tension for coating and a coater head is bent so as to follow the bending of the support by a back roll.
No. 47661, a method of arranging a cylindrical cone having a rotatable slit in a manifold (coating liquid reservoir) of a coater, as described in JP-A-11-128805, In the case of applying a high-viscosity coating liquid having the following, a method using a coater head having two or more coating liquid supply ports has been proposed.

[0007] The coater head generally gives higher accuracy by grinding, but the grinding accuracy is degraded as the width of the object to be ground becomes wider. In the conventional method of coating the entire width using one coater head, the longer the coating width, the longer the length of the coater head, and the lower the straightness accuracy (production accuracy), the worse the slit gap accuracy. As a result, it becomes extremely difficult to obtain a uniform film thickness distribution when coating a support having a wide coating width.

[0008] Even if a conventional means for mechanically adjusting the gap is used to compensate for this, not only is the apparatus large and expensive, but also the adjustment operation is difficult, and the gap is adjusted to the desired gap with high precision. It is difficult.

[0009] In the recent technology described above, the coating width is 1
It is effective for applications that are not so wide, such as within m,
If it exceeds 1 m, the device is large and expensive, and the adjustment operation is difficult, and a sufficient effect cannot be obtained.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method of forming a support which can be applied to a wide support efficiently and easily. It is an object of the present invention to provide a coating method in which the thickness of the coating layer is uniform and which is advantageous for improving the productivity.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a coating apparatus in which a plurality of dies are arranged in parallel in a width direction of a long support to be conveyed so as to face a back roll supporting the support. A coating method in which a layer is formed, wherein all of the plurality of dice are arranged so as to face one back roll, and (2-1) the plurality of dice are located at the same position with respect to the transport direction of the support. Or (2-2) at least one of the plurality of dice is arranged at a different position with respect to the transport direction of the support, wherein at least one of the plurality of dice is another die Is disposed so as to face a back roll different from the back roll disposed so as to face, and in (2-2), there is no region where a coating layer is not formed between dies in the width direction of the support. To Arranging a plurality of dice in such a manner that an area where the coating layer is not formed in the width direction of the support overlaps with a range rejected by cutting after coating in the steps of: A coating device having a variable mechanism, a plurality of dice covering a part of the entire coating width, and a coating device arranged to face at least one back roll; (7-1) a plurality of dice are all in one back Being arranged in series, facing the roll, (7-
2) All of the plurality of dice face one back roll, and at least one of the plurality of dice faces each other at a different position from the other dice, and is arranged, (7-3) 2 It has the above-mentioned back roll, and at least one of the plurality of dice is arranged to face a back roll different from the back roll to which another die is arranged to face, and the individual dice are positionally variable. This is achieved by having a mechanism.

That is, the inventor of the present invention uses a plurality of dies having an application width corresponding to the width of the product after cutting in parallel to reduce the application width per die, so that the entire coating width can be reduced.
The present inventors have found that a coating having a film thickness distribution equivalent to that of narrow-width coating can be obtained, and have reached the present invention.

Generally, it is considered that the grinding accuracy decreases as the size of the workpiece increases, and the straightness accuracy deteriorates substantially in proportion to the square of the length. Therefore, if a single die is used to manufacture a double length die so that, for example, a double coating width can be applied, the straightness value is about four times, and the straightness of the original coater head is approximately four times. Is, for example, 5 μm, it is about 20 μm, which is greatly deteriorated.

This decrease in accuracy causes a deterioration in the uniformity of the gap of the coating liquid discharge port flow passage (also referred to as a slit or a slot) in the die in the coating width direction. Because of the decline,
In the worst case, the accuracy is further doubled. For example, in the case of a coater having a slit gap of 200 μm, when the straightness of the coater head is 5 μm, (5/200) × 2
= 5% coating film uniformity (film thickness variation), but when it is deteriorated to 20 μm, the coating film uniformity becomes (20/20
0) × 2 = 20%, which is significantly worse. In general, the film thickness distribution in the width direction is three times the slit gap accuracy in the width direction of the coating.
It is said that the variation width of the width-thickness distribution in the above case greatly deteriorates from about 16% to about 70%, resulting in a coated surface quality that does not become a product at all.

As a method for preventing such deterioration of the film thickness distribution, various known examples as described above can be mentioned.
As a result of the inventor's diligent studies including these improvements, rather than simply increasing the length of the die itself to obtain a wide coating, a plurality of short dies are installed in the application width,
It has been found that by realizing wide-width coating, extremely uniform coated surface quality can be obtained.

Hereinafter, the present invention will be described in detail. The present invention is characterized in that a plurality of dies are arranged in parallel in the width direction of a long support to be conveyed, facing a back roll supporting the support, and a coating layer is formed.

In the present invention, the term “die” refers to a coating liquid extrusion nozzle that spreads the fed coating liquid uniformly in the coating width direction and applies the coating liquid to the support. Usually, there is a liquid pool portion extending in the coating width direction called a chamber or a pocket inside, and the coating liquid is supplied to the center of this width or an arbitrary position and is spread in the coating width direction and then slit. Alternatively, it is extruded onto a support from a tip called a lip or an edge through a narrow passage between flat plates called a slot or the like. In a single-layer coating die, these liquid pools and slits are usually one set, and are constituted by two blocks called a front bar, a back bar, etc., and fixed by bolts or the like. In a die for simultaneous application of a plurality of layers, by increasing the number of bars, liquid pools and slits are formed by the number of application layers. The dice used in the present invention is not particularly limited, and a known die can be used. The shape of the edge of the die is not particularly limited, and it is preferable to appropriately select and use the shape in accordance with the viscosity and flow characteristics of the coating solution to be used, or the coating conditions such as the coating speed and the coating film thickness.

Since the cylindricity of the back roll greatly affects the accuracy of the gap between the die lip and the support in the width direction, the back roll is preferably made of a metal having a diameter of 200 mm or more.

A plurality of dies D1 to Dn are arranged in the width direction of the support.
As a method of arranging, there is a method of arranging them at the same position (in series) with respect to a support 2 which is wound around a back roll 1 and travels as shown in FIG. The application width end of the die is sealed with various width regulating means, side plates, or the like so that a desired application width can be obtained. Since the sealing means has a certain width, in a system in which the dice are arranged side by side, at least the width of the sealing means is an uncoated portion.

The uncoated portion is cut off in the same manner as in the end cutting in the width direction of the support at the time of ordinary cutting. For products such as video tapes, audio tapes and tapes such as various adhesive tapes that are cut into many products with a narrow width after cutting, even if the uncoated portion is not aligned with the cutting position, This can be handled by discarding the product at the corresponding position after cutting. The cutting device used in the present invention is not particularly limited, and a known device can be used.

In the case of a support having a very large width and an embossed portion in the middle of the width direction, the embossed portion is usually cut and cut. By adjusting the position, loss of the support can be prevented.

In supporting and coating the support with the back roll, if the coating solution has a high volatility, the portion in contact with the coated support may be deprived of heat of vaporization and cooled and shrunk. It is preferable to prevent the application liquid from evaporating from the application surface until the application is completed with the die. Specific examples thereof include, but are not limited to, a method of lowering the peripheral temperature, lowering the temperature of the coating solution, lowering the back roll temperature in advance, and increasing the concentration of the evaporated component in the periphery. Not done.

As shown in FIG. 2, when at least one of a plurality of dies arranged opposite to the back roll 1 is arranged at a different position in the conveying direction of the support 2, FIG. As shown, there is a case where a back roll is arranged for each individual die. Of course these and Figure 1
May be used in combination.

FIG. 4 shows a case where the coating width 3 is set so as not to overlap with the method shown in FIG. 2, and uncoated portions 5 and 6 are formed between the end and the die with respect to the support width 4. But,
In the method of FIG. 2 or FIG. 3, since the position of each die in the width direction of the support can be arbitrarily set without interfering with other dies, the individual positional relationship between the dies is eliminated so that the uncoated portion is eliminated. By appropriate adjustment, as shown in the plan view of FIG. 5, the finished coating surface can be made the same coating film as if the coating was performed with a single coater head. By setting the finished film thickness after drying to be the same or within the product standard, it is possible to apply without having to consider the cutting position after application as described above, and the cutting position is also optional as in the case of coating with a single die. It can be cut at the position in the width direction of
Of course, it is also possible to make a large-sized product with the same width without cutting.

The mechanism for changing the individual positions of the plurality of dies is not particularly limited, and may be appropriately performed by a moving method using a gear or a system method of automatically detecting the application position and moving to the target application position. In order to move the application position using a plurality of (n) dies, at least (n)
-1) It is preferable to provide a variable function on one of the dies and correct the application position of each die so as to eliminate the uncoated portion.

When a coating failure such as a streak occurs during coating or when cleaning of the dice becomes necessary, the individual dice can be individually retracted so that the dice can be temporarily retracted from the support. By adopting a simple mechanism, only the dice in which a failure has occurred can be retracted, and the application of the other dice can be continued, the loss can be reduced, and the yield can be improved, which is preferable.

The coating liquid supply system is composed of a supply pot, a pipe, and a supply pump. If necessary, a valve, a liquid discharge port, a filter, a flow meter, a defoamer, a heat exchanger, a stirrer, etc. may be provided at various points in the pipe. Are often used together. The supply pot or the pipe may be subjected to a water-repellent treatment such as a fluorine treatment so as to easily clean the liquid contact portion. Since the coating film thickness of the dies is determined by the liquid supply amount, the supply of the coating liquid is required to have high precision, and in order to minimize fluctuations in the flow rate, high precision liquid pumps such as precision metering gear pumps and plunger pumps are required. It is preferable to use flow control or the like.

According to the present invention, at least one die has two
More than one coating constituent layer can be simultaneously coated in multiple layers, and the number of coating layers is not particularly limited. Further, the coating method of the present invention can also be applied to coating on a support on which some coating constituent layers have been coated in advance.

The type of the support used in the present invention is not particularly limited, and paper, plastic film, metal sheet and the like can be used. Examples of the paper include resin-coated paper and synthetic paper. Examples of the plastic film include a polyolefin film (eg, a polyethylene film, a polypropylene film, etc.), a polyester film (eg, a polyethylene terephthalate film, a polyethylene 2,6-naphthalate film, etc.), a polyamide film (eg, a polyetherketone film, etc.), Cellulose acetate (for example, cellulose triacetate and the like) and the like can be mentioned. In addition, an aluminum plate is representative of a metal sheet. Also, there is no particular limitation on the thickness of the support used.

The coating solution that can be used in the present invention is not particularly limited, and examples thereof include a magnetic coating solution for a magnetic recording medium, a coating solution for general and industrial silver halide photosensitive materials,
Examples include a coating solution for a heat-sensitive material, a coating solution for a photothermographic material, a solution in which a polymer material is dissolved in an organic solvent, water, or the like, a pigment dispersion, a colloidal dispersion, and the like.

[0031]

EXAMPLES Hereinafter, the effects of the present invention will be described specifically with reference to examples, but the present invention is not limited to these embodiments.

Example 1 << Preparation of Photothermographic Material >> A photothermographic material was prepared according to the following method.

(Preparation of Subbed Support) A commercially available biaxially stretched heat-fixed support having a width of 2200 mm and a thickness of 100 μm polyethylene terephthalate (hereinafter simply abbreviated as PET).
A corona discharge treatment of 8 W / m ² · min is applied to both surfaces of the film, and the following undercoating coating solution a-1 is applied to one surface with a dry film thickness of 0.8.
μm, and dried to form an undercoat layer A-1,
On the other side, the following undercoating coating solution b-1 was dried to a thickness of 0.
It was applied so as to have a thickness of 8 μm, and was dried to obtain an antistatic processed undercoat layer B-1.

<Undercoating Coating Solution a-1> A copolymer of butyl acrylate (30% by mass), t-butyl acrylate (20% by mass), styrene (25% by mass), and 2-hydroxyethyl acrylate (25% by mass) Combined latex liquid (solid content 30%) 270 g (C-1) 0.6 g Hexamethylene-1,6-bis (ethylene urea) 0.8 g Finish to 1 L with water <Undercoat coating solution b-1> Butyl acrylate ( 40% by mass), styrene (20% by mass), glycidyl acrylate (40% by mass) copolymer latex liquid (solid content 30%) 270 g (C-1) 0.6 g hexamethylene-1,6-bis (ethylene (Urea) 0.8 g Finish to 1 L with water. Next, on the upper surface of the undercoat layer A-1 and the undercoat layer B-1,
A corona discharge of 8 W / m ² · min. Is applied, and a lower coating layer a-1 is applied on the lower coating layer A-1 so as to have a dry film thickness of 0.1 μm. -2, and the undercoat layer B-
On top of 1, the undercoating upper layer coating solution b-2 was dried to a thickness of 0.8 μm.
Was applied as an undercoating upper layer B-2 having an antistatic function so as to obtain an undercoated support.

<Coating solution a-2 for lower undercoat> Gelatin 0.4 g / m ² Mass (C-1) 0.2 g (C-2) 0.2 g (C-3) 0.1 g Silica particles ( (Average particle size: 3 μm) 0.1 g Finished to 1 L with water <Lower upper coating liquid b-2> (C-4) 60 g Latex liquid containing (C-5) as a component (solid content: 20%) 80 g Ammonium sulfate 0. 5g (C-6) 12g Polyethylene glycol (weight average molecular weight 600) 6g Finish to 1L with water

[0036]

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[0037]

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(Heat Treatment of Support) In the above-mentioned undercoat drying step of the undercoated support, the support is heated at 140 ° C.
Thereafter, it was gradually cooled.

(Preparation of silver halide emulsion) 900 ml of water
Inert gelatin 7.5g and potassium bromide 10m
g was dissolved and the temperature was adjusted to 35 ° C. and the pH to 3.0.
370 ml of an aqueous solution containing 74 g of silver nitrate, an aqueous solution containing potassium bromide and potassium iodide in a molar ratio of (98/2) and [Ir (NO) Cl ₅ ] salt were added in an amount of 1 × 10 ⁻⁶ per mole of silver.
The mol and rhodium chloride were added by the controlled double jet method at 1 × 10 ⁻⁴ mol per mol of silver while maintaining the pAg at 7.7. Then, 4-hydroxy-6-
Methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with NaOH, the average particle size was 0.06 μm, the monodispersity was 10%, the variation coefficient of the projected diameter area was 8%, [ 100] Cubic silver iodobromide grains having an area ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment, and then adjusted to pH 5.9 and pAg 7.5 by adding 0.1 g of phenoxyethanol to obtain a silver halide emulsion. Then, to the obtained silver halide emulsion,
Chemical sensitization was performed with chloroauric acid and inorganic sulfur.

The monodispersity and the variation coefficient of the projected diameter area were calculated by the following equations. Monodispersity = (standard deviation of particle size) / (average value of particle size) × 1
00 Coefficient of variation of projected diameter area = (standard deviation of projected diameter area)
/ (Average value of projected diameter area) × 100 (Preparation of Na behenate solution) In 945 ml of pure water, 32.4 g of behenic acid, 9.9 g of arachidic acid and 5.6 g of stearic acid were dissolved at 90 ° C. Next, 98 ml of a 1.5 mol / L aqueous sodium hydroxide solution was added while stirring at a high speed. Then, after adding 0.93 ml of concentrated nitric acid, 5
The solution was cooled to 5 ° C. and stirred for 30 minutes to prepare a sodium behenate solution.

(Preparation of Preform Emulsion of Silver Behenate and Silver Halide) 15.1 g of the above silver halide emulsion was added to the above sodium behenate solution, and the pH was adjusted to 8.1 with a sodium hydroxide solution. 1 mol / L silver nitrate solution 1
47 ml was added over 7 minutes, the mixture was further stirred for 20 minutes, and water-soluble salts were removed by ultrafiltration. The obtained silver behenate was grains having an average grain size of 0.8 μm and a monodispersity of 8%. After forming the flocs of the dispersion, remove the water,
After performing water washing and water removal six more times, the emulsion was dried to prepare a preform emulsion.

(Preparation of Photosensitive Emulsion) A polyvinyl butyral (average molecular weight of 30) was added to the preform emulsion prepared above.
00) in methyl ethyl ketone (17% by mass) 544
g and 107 g of toluene were gradually added and mixed, and then dispersed at 27.6 MPa using a media disperser.

(Preparation and Coating of Coating Solution) The following layers were sequentially formed on a support to prepare a photothermographic material. still,
Drying was performed at 60 ° C. for 15 minutes each.

(Back surface side coating) A back surface side coating solution having the following composition was applied onto the undercoating upper layer B-2 of the support prepared above.
Coating was performed using a known coating machine.

<Coating Solution on Back Side> Cellulose acetate (10% methyl ethyl ketone solution) 15 ml / m ² dye-B 7 mg / m ² dye-C 7 mg / m ² Matting agent: monodispersity 15% Average particle size 10 μm monodisperse Silica 30 mg / m ² C ₉ H ₁₉ —C ₆ H ₄ —SO ₃ Na 10 mg / m ²

[0046]

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(Coating on the photosensitive layer side) A photosensitive layer coating solution and a surface protective layer coating solution having the following compositions were used in a coating method described later using a two-layer simultaneous multilayer coating die, and the amount of silver coated on the photosensitive layer was 2.
Coating was performed so as to be 1 g / m ² .

<Preparation of coating solution for photosensitive layer> Preform emulsion 240 g Sensitizing dye-1 (0.1% methanol solution) 1.7 ml Pyridinium bromide perbromide (6% methanol solution) 3 ml Calcium bromide (0.1 1.7 ml Antifoggant-2 (10% methanol solution) 1.2 ml 2- (4-chlorobenzoyl) benzoic acid (12% methanol solution) 9.2 ml 2-mercaptobenzimidazole (1% methanol solution) 11 ml Tribromomethylsulfoquinoline (5% methanol solution) 17 ml Developer-1 (20% methanol solution) 29.5 ml

[0049]

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<Preparation of Coating Solution for Surface Protective Layer> Acetone 35 ml / m ² methyl ethyl ketone 17 ml / m ² cellulose acetate 2.3 g / m ² methanol 7 ml / m ² phthalazine 250 mg / m ² 4-methylphthalic acid 180 mg / m ² tetrachloro Phthalic acid 150 mg / m ² Tetrachlorophthalic anhydride 170 mg / m ² Matting agent: Monodispersity 10% Average particle size 4 μm Monodisperse silica 70 mg / m ² C ₉ H ₁₉ —C ₆ H ₄ —SO ₃ Na 10 mg / m ² coating method 1: die four coating width 500 mm, arranged from 25mm position than the support ends, in parallel with 50mm intervals in the same position in the transport direction of the support in the form as shown in Figure 1, Coating was performed with the same amount of coating liquid supplied. After the coating was completed, the coated portion was cut into a width of 500 mm to prepare a photothermographic material 1. In the cutting step, uncoated portions between the dies were cut off by 50 mm each, and both ends in the width direction of the support were cut off by 25 mm each.

Coating method 2: Die 4 having a coating width of 500 mm
A photothermographic material 2 was prepared in the same manner as in the coating method 1, except that two dies having a coating width of 1000 mm were used instead of the pedestal. In the cutting step, the uncoated portion was cut off by 100 mm, and both ends in the width direction of the support were cut off by 50 mm.

Coating method 3: One die having a coating width of 2000 mm was placed at a position 100 mm from both ends in the width direction of the support, and coating was performed. After the application is completed, the application area is 500m
The resulting photothermographic material 3 was cut to a width of m. In the cutting step, both ends in the width direction of the support were cut off by 100 mm.

<< Evaluation of Quality of Coated Sample >> The photothermographic materials 1 to 3 obtained as described above were exposed and developed according to the following methods, and then evaluated for density unevenness in the width direction. .

(Exposure and Development Processing) Each of the prepared photothermographic materials was subjected to a heat development processing at 110 ° C. for 15 seconds using an automatic developing machine having a heat drum without exposing. At that time, the test was performed in an atmosphere of 23 ° C. and 50% RH.

(Measurement of Density Unevenness) Using a spectrophotometer UV-1200 manufactured by Shimadzu Corporation, the transmission density of each developed sample at 400 nm was measured, and the density was 50% of the overall average value. If the area is low and the area exceeds 50 microns in diameter, it is judged as a coating defect point and excluded from the measurement, and the standard deviation is used as a measure of the density unevenness for the density measurement value of 100 points per 1 m in the width direction. (%) Was calculated.
%, 2.1% for coating method 2 and 5.5% for coating method 3.

Example 2 Each of the coating methods of Example 1 was applied for 10,000 m, and the yield of non-defective parts excluding defective parts was compared. The yield was 99% by coating method 1 and 97% by coating method 2; Method 3 yielded 89%.

Example 3 A support having a width of 2200 mm was 2,000 mm thick by the following method.
Was formed, and the density unevenness in the width direction at a width of 2000 mm was evaluated in the same manner as in Example 1.

Coating method 4: Using two back rolls as shown in FIG. 3, two dies each having a coating width of 500 mm are inclined in the width direction by changing the position in the running direction of the support as shown in FIG. It was placed on a mat and applied. The positions of the dies were adjusted so that no uncoated portion was formed between the dies, and the conditions were such that the amount of the coating liquid supplied to each of the dies was the same and the same average film thickness was obtained.

Coating method 5: Two dice having a coating width of 1000 mm were placed on one back roll and placed diagonally in the width direction while changing the position in the running direction of the support as shown in FIG. Application was performed. The positions of the dies were adjusted so that uncoated portions were not formed, and the conditions were such that the amount of the coating liquid supplied to each of the dies was the same and the same average film thickness was obtained.

Coating method 6: Coating was performed on each of two dies having a coating width of 1000 mm using a back roll as shown in FIG. The positions of the dies were adjusted so that no uncoated portion was formed between the dies, and the conditions were such that the amount of the coating liquid supplied to each of the dies was the same and the same average film thickness was obtained.

As a result, the standard deviation of the concentration variation is 2
At 000 mm, coating method 4 is 1.0%, coating method 5 is 2.2%, coating method 6 is 2.1%, and coating method 3 is 15%.
1%.

Example 4 A magnetic recording material for a floppy (registered trademark) disk having a size of 100 MB or more was produced according to the method described below.

(Preparation of Coating Solution) <Coating Solution for Magnetic Layer: Upper Layer> Ferromagnetic metal powder (Hc: 2350 Oe, σs: 155 emu / g, average major axis length: 0.1 μm, specific surface area: 50 m ² / g) 100 parts Vinyl chloride copolymer (manufactured by Zeon Corporation: MR110, degree of polymerization: 300) 10 parts Polyurethane resin (manufactured by Toyobo Co., Ltd .: UR8300) 5 parts Carbon black (manufactured by Columbia Carbon Corporation: Conductex 975) 1 part Alumina ( Sumitomo Chemical Co., Ltd .: HIT50) 10 parts Diamond fine powder Average particle diameter 0.3 μm 1 part Phenylphosphonic acid 3 parts Butyl ethyl stearate 10 parts Butoxyethyl stearate 5 parts Isohexadecyl stearate 3 parts Stearic acid 2 parts Methyl ethyl ketone 180 parts Cyclohexanone 180 parts <Non-magnetic layer coating solution: lower layer> Non-magnetic powder needle Hematite (manufactured by Nippon Chemical Industrial Co., Ltd.: DPN550BX average long axis length: 0.14 .mu.m, specific surface area: 50 m ² / g, average minor axis length: 0.024) 100 parts Carbon black (Columbia Carbon Co., Ltd. CONDUCTEX Tex SC-U Mean Primary particles: 20 nm or less) 12 parts Vinyl chloride copolymer (manufactured by Zeon Corporation: MR104 polymerization degree: 250) 15 parts Polyurethane resin (manufactured by Toyobo Co., Ltd .: UR8300) 6 parts Phenylphosphonic acid 4 parts Butyl stearate 10 parts Butoxyethyl Stearate 5 parts Isohexadecyl stearate 2 parts Stearic acid 3 parts Methyl ethyl ketone 150 parts Cyclohexanone 100 parts For the above magnetic layer coating solution and non-magnetic layer coating solution, each component is kneaded with a kneader, and then mixed with the magnetic layer coating solution. After adding the required diamond fines And dispersed using a sand mill. To each of the obtained dispersions, 13 parts of a polyisocyanate (Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was added to the nonmagnetic layer coating solution, 4 parts of the magnetic layer coating solution was added, and 40 parts of cyclohexanone was further added to each. , 1μm
The mixture was filtered using a filter having an average pore size of to prepare a coating solution for each layer.

(Preparation of Disk-shaped Magnetic Recording Material) The thickness of the non-magnetic layer coating solution prepared above was adjusted to 1.5 μm after drying, and then the thickness of the magnetic layer coating solution was dried thereon. 2200 mm width, thickness 62 so that it becomes 0.2 μm
Using a coating apparatus described in JP-A-2-251265, simultaneous multilayer coating was performed on a PET support having a thickness of 3 μm and a center average surface roughness of 3 nm by the following coating methods 7 to 9. Then, while the coating film is still wet, the frequency 50H
z, a magnetic field strength of 250 Gauss, a frequency of 50 Hz, a magnetic field strength of 120 Gauss, and a random orientation treatment by passing through two AC magnetic field generators, and after drying, a 7-stage calender at a temperature of 90 ° C. and a linear pressure of 34.3 MPa. A surface smoothing treatment was performed. Next, after punching each magnetic recording material into a disk state, a heat treatment was performed at 65 ° C. for 24 hours, and a surface treatment was further performed to remove fine protrusions on the surface with a polishing tape. 3 was produced.

Coating method 7: Die 4 having a coating width of 500 mm
The tables were placed in parallel in the form shown in FIG. 1 so as to be at the same position in the direction of transport of the support, and coating was performed to produce a magnetic recording material 1. After coating and drying, the uncoated portion between the dies was punched out in a disk shape and then sorted and discarded.

Coating method 8: Two dies having a coating width of 1000 mm are arranged in parallel in the form shown in FIG. 1 so as to be at the same position in the transport direction of the support, and coating is performed. Produced. After coating and drying, the uncoated portion between the dies was punched out in a disk shape and then sorted and discarded.

Coating method 9: Coating was performed using one coater head having a coating width of 2000 mm, and a magnetic recording material 3 was produced.

(Evaluation of Characteristics of Disk-shaped Magnetic Recording Material) 500 samples of each magnetic recording material thus produced were sampled arbitrarily, small pieces were embedded in methacrylic resin, and thin sections having a thickness of about 50 μm were cut from the cross section with a diamond cutter. Was cut out, photographed with an electron microscope, the film thickness of the coating layer was measured, and the standard deviation (%) of the measured value was evaluated as the film thickness variation of the sample. The ratio was 1.4% for the magnetic recording material 2 and 9.5% for the magnetic recording material 3. The error rate of the magnetic recording material 1 was 1 × 10
^-5 , 1.5 × 10 ^-5 for magnetic recording material 2, magnetic recording material 3
^Was 12 × 10 ⁻⁵ . That is, it can be seen that the magnetic recording material produced by the coating method according to the present invention has a small thickness variation width for each product, reduces the out-of-spec products, improves the yield, and dramatically improves the error rate.

[0069]

According to the coating method of the present invention, a coating layer having a uniform thickness can be obtained by coating on a wide support, and the work efficiency can be improved and the production efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a model diagram showing one embodiment of a coating method of the present invention.

FIG. 2 is a model diagram showing another embodiment of the coating method of the present invention.

FIG. 3 is a model diagram showing still another embodiment of the coating method of the present invention.

FIG. 4 is a diagram showing an example of a region of a coating layer to be formed.

FIG. 5 is a diagram showing an example in which coating is performed so that an uncoated portion between dies is not formed.

[Explanation of symbols]

 Reference Signs List 1 back roll 2 support 3 coating width 4 support width 5, 6 uncoated portion

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G03C 1/74 351 G03C 1/74 351 5D112 G11B 5/848 G11B 5/848 F term (reference) 2H023 EA01 2H123 BC01 4D075 AC05 AC72 AC88 AC93 AE02 AE22 CA48 DA04 DB07 DB18 DB33 DB36 DB48 DB53 DC27 EA06 EA07 EA10 EA12 EB14 EB15 EB22 EB33 EB38 4F041 AA12 AB02 BA05 BA13 BA21 CA02 4F042 AA22 ED02 ED05 5D112 AA05 CC07 CC07

Claims (13)

[Claims] 1. A coating method wherein a plurality of dies are arranged in parallel in a width direction of a long support to be conveyed so as to face a back roll supporting the support, and a coating layer is formed. Method. 2. The apparatus according to claim 1, wherein all of the plurality of dies are arranged to face one back roll.
Coating method. 3. The coating method according to claim 2, wherein the plurality of dies are arranged at the same position with respect to the direction of transport of the support. 4. The coating method according to claim 2, wherein at least one of the plurality of dies is arranged at a different position with respect to the direction of transport of the support. 5. The method according to claim 1, wherein at least one of the plurality of dice is arranged to face a back roll different from the back roll to which another die is arranged to face. Coating method. 6. The coating method according to claim 4, wherein the dice are arranged such that there is no region where no coating layer is formed between the dice in the width direction of the support. 7. A plurality of dies are arranged so that a region where a coating layer is not formed in the width direction of the support overlaps a range rejected by cutting after coating. 6. The coating method according to 4 or 5. 8. The coating method according to claim 1, wherein each die has a position variable mechanism. 9. An application apparatus, wherein a plurality of dies covering a part of the entire application width are arranged to face at least one back roll. 10. The coating apparatus according to claim 9, wherein all of the plurality of dies are arranged in series facing one back roll. 11. A method in which all of the plurality of dice face one back roll, and at least one of the plurality of dice is arranged facing a different position from the other dice. The coating device according to claim 9. 12. A back roll having at least two back rolls, wherein at least one of the plurality of dies is arranged to face a back roll different from the back roll to which another die is arranged to face. The coating device according to claim 9, wherein 13. The coating apparatus according to claim 9, wherein each die has a position variable mechanism.