JPH05293425A - Coating method - Google Patents

Abstract

PURPOSE:To increase the effective coefficient of utilization of a magnetic layer by eliminating the objectionable magnetic layer expanding parts generated at both edge parts of an undercoat layer in a method for coating a magnetic tape or the like. CONSTITUTION:In a state sealed with the org. solvent type liquid preliminarily applied to the surface to be coated of a support 1, a coating layer is formed on the support by an extrusion type coating head having the front edge 2 positioned on the upstream side in the moving direction of the support and the back edge 3 positioned on the downstream side in the moving direction of the support 1 so that the leading end thereof retreats from the front edge with difference in level in the direction separating from the support and having an acute leading end part. Both edge part precoat layers 11 formed on the underside of a coating layer 7 have adhesiveness and the coating layer 7 is applied so that both edge part precoat layers 11 are exposed at least from the edge parts in the lateral direction of the coating layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion type head for applying a coating solution continuously extruded toward a moving flexible support surface onto the surface of the support with a uniform thickness. A novel coating method.

[0002]

2. Description of the Related Art Conventionally, various coating methods and coating apparatuses have been used, as is well known, for coating a coating liquid such as a magnetic dispersion liquid. And, as one of the coating techniques, there are, for example, JP-A-61-139929 and JP-A-58-205561. In these coating methods and apparatuses, the upstream side edge is formed by a precoat layer. Since it is liquid-sealed, air entrainment in the coating layer is blocked, and thin layer coating can be realized at high speed. However, in this type of coating method, a pressure is applied between the downstream edge and the support, and the coating layer is smoothed. Therefore, when there is unevenness in the width direction of the support, the coating film thickness also varies. It becomes uneven in the direction. Furthermore, when foreign matter is mixed on the support or in the precoat coating layer coating liquid,
It is easy to be trapped on the downstream edge, which easily causes streaks. The coating liquid mentioned here is, for example, a photographic photosensitive coating liquid, a magnetic coating liquid, a coating liquid for surface protection / antistatic or lubricity, and its typical products are various photographic films and photographic papers. , Magnetic recording media, etc.

The applicant of the present invention has previously improved these characteristics to avoid streak failure and fluctuations in the coating film thickness due to nonuniformity of the thickness of the support, Young's modulus, etc. Further, when the coating solution passes through the slot. As a coating apparatus capable of reducing pressure loss, the coating apparatus described in Japanese Patent Application Laid-Open No. 63-20069 was filed. In Japanese Patent Laid-Open No. 630069/1988, as shown in FIG. 5, the magnetic coating liquid 7 is applied in a state of being sealed with a precoat layer 6 of an organic solvent or the like previously applied to the application surface of the support 1. , A front edge 2 located upstream with respect to the support moving direction, and a front edge 2 located downstream with respect to the support moving direction, the tip of which is stepped from the front edge and retracts in the direction opposite to the support. There is disclosed a coating apparatus for forming a coating layer on a support by an extrusion type head having a back edge 3 having a sharp tip. The precoat layer 6 is a so-called undercoat layer that improves the adhesion of the magnetic coating liquid 8 to the support 1. The magnetic coating liquid 7 is supplied to the pocket 5 from a liquid supply system (not shown), and the coating liquid 7 is stored in the pocket 5 and then pushed out to the slit 8.

The organic solvent is first applied to the coated surface of the support 1 by a commonly used known coating apparatus such as a gravure coater, a roll coater, a blade coater and an extrusion coater. Intrusion of entrained air from the upstream side of the front edge into the coating layer is prevented, a defect-free coating state is maintained, and high-speed coating characteristics are enhanced. The front edge 2 is located on the upstream side of the support 1 from the exit of the slit 8 and is formed so that the entire edge surface facing the support 1 bulges toward the support. A curved surface having a curvature is generally used as a form of bulging toward the support side,
The shape is not limited to this as long as entrainment of entrained air can be prevented.

The back edge 3 is located such that the tip end 10 and the entire back edge surface of the back edge 3 recede in the direction opposite to the supporting body with respect to the tangent at the exit of the slit 8 of the front edge 2. As a result, the pressing force at the time of coating does not work between the back edge 3 and the support 1,
It is possible to prevent foreign matters from being trapped at the same portion, and it is possible to reduce failure of the coated surface due to the foreign matters. As described above, according to the coating device shown in FIG. 5, the generation of streaks can be extremely reduced without trapping foreign matter.
Depending on the coating conditions of the precoat layer, there has been a problem that entrainment of air from the upstream side of the front edge 2 may occur at both edge portions in the width direction, or a thickness defect of the magnetic coating liquid may occur at both edge portions. The problem of the entrained air described above is that the entrained air is likely to enter because the so-called hydraulic pressure is so small that the coating liquid is not pressed against the support 1 during coating.

When the magnetic layers 6 and 7 are applied to the support 1 as shown in an enlarged cross section of the magnetic recording medium in FIGS. 6 and 7, the support 1 of the magnetic layer 7 is usually used. It is applied on the precoat layer 6 (undercoat layer) having adhesiveness to prevent peeling from the surface. Here, the magnetic coating layer 7 is formed as shown in FIG.
When the coating width is narrower than that of the precoat layer 6 as shown in FIG. 3, the magnetic coating layer 7 can be prevented from peeling from the support 1, but after the coating, the magnetic recording medium is wound into a roll. Since the precoat layer 6 is carried and stored, the exposed portion 20 of the magnetic coating layer 7 adheres to the adjacent support 1. In order to solve this problem, the conventional method shown in FIG.
The magnetic coating layer 7 is applied so as to cover the precoat layer 6 as shown in FIG.

However, when the magnetic layer 7 is coated so as to cover the precoat layer 6, the cause of the occurrence is not clear, but the extensibility of the magnetic coating layer 7 at the portion where the precoat layer 6 is not wetted. Probably because the magnetic layer on both edges without the precoat layer 6 does not have a desired thickness, the magnetic layer bulging portion P that rises as shown in FIG. Has been found to be formed. Not only is it a product that is disqualified as a product at both edges of the support 1 as described above and the yield is reduced, but further, in a later step, for example, a calendering device and other various devices of the transport system are destroyed. There was a problem that caused a serious failure that could not be combined. In addition, the support 1
Even when the magnetic layer 7 is directly applied to
The magnetic layer bulging portion P shown in FIG. 7 is formed, and both end portions of the support 1 are unusable as a product, and there is a problem that the yield is reduced.

[0008]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the drawbacks in terms of wicking, and its object is to eliminate the magnetic layer bulging portions P formed at both edges of the undercoat layer. In other words, the effective utilization rate of the magnetic coating layer is increased to improve its economical efficiency.

[0009]

The above-mentioned object of the present invention is to prevent the flexible substrate from being moved in the direction of movement of the substrate while being liquid-sealed by a liquid of an organic solvent system previously coated on the coated surface of the substrate. And a front edge located on the upstream side and a downstream side with respect to the moving direction of the support, the tip of which is stepped from the front edge and recedes in the direction opposite to the support, and the tip has an acute angle. By an extrusion type coating head having an edge, in a coating method for forming a predetermined coating layer on the support, both edge precoat layers formed on the lower side of the coating layer are non-adhesive, A solution is provided by a coating method, characterized in that, when the coating layer is coated, the both-sides precoat layers are coated so as to be exposed at least from the widthwise edges of the coating layer. Further, the above-mentioned problem is that when an undercoat layer having adhesiveness is formed on the lower layer side of the coating layer in addition to the both edge precoat layers, the coating width of the undercoat layer is smaller than the width of the coating layer. And so that the sum of the width of the undercoat layer and the width of both edge precoat layers applied to both ends of the undercoat layer is larger than the width of the coating layer, the undercoat layer and the both This can be solved by a coating method characterized by coating the coating layer while scraping off the edge precoat layer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A coating apparatus to which the coating method of the present invention is applied will be described below. The illustrated coating device is a device for coating a magnetic coating liquid. First, a cross-sectional view of the coating head of the present embodiment shown in FIG. 3 and a coating state by the coating head will be described. The front edge 2 is formed so that the entire front edge surface 2a facing the support 1 swells toward the support side.
Generally, a curved surface having a curvature (R) is used,
The shape is not limited to this and may be a flat shape as long as it can prevent the entrainment of air entrained in the support. Further, the tip portion 10 of the back edge 3 and the entire back edge surface are configured to be lower than the top portion of the front edge 2. That is, the tip portion 10 of the back edge 3 is configured to be recessed with respect to the rear end portion 9 of the front edge 2 so as to be retracted with respect to the support 1.

The slit 8 extends from the pocket 5 to the support 1
The taper may have a taper toward the application point or may be parallel as shown in the drawing. In this embodiment, the undercoat layer 6 and the both-edge precoat layers 11 (see FIG. 2) correspond to the conventional precoat layers. The undercoat layer 6 and the precoat layer 11 are respectively coated in front of the coating device shown in FIG. The coating heads for forming the undercoat layer 6, the precoat layer 11 and the coating layer 7 of the magnetic coating liquid are appropriately arranged with a predetermined gap, but these coating devices are provided with two different guides. They may be installed separately between the rolls, or may be installed simultaneously between the two guide rolls. The wrap angle of the support in the coating head for the magnetic coating liquid shown in the figure is generally 2 ° to 60 °, and the span of the guide roll for forming the wrap in the coating liquid coating head is generally 50 to 300 mm. It is not limited to this.

Next, a coating apparatus for the undercoat layer 6 and the both edge precoat layers 11 will be described. This coating device is not particularly limited, for example, a gravure coater,
The coating is performed by a well-known coating device that is generally used, such as a roll coater, a blade coater, and an extrusion coater. The undercoat layer 6 applied in advance
The both edge precoat layers 11 are organic solvent-based liquids and have a lower viscosity than the magnetic coating liquid 7, and the action thereof is the same as the conventional magnetic coating liquid 7 in addition to the action described later. The entrainment of entrained air on the upstream side of the front edge when the is applied is prevented, and a suitable applied state is maintained.

In the present invention, the coating layer 7 is
The magnetic recording medium includes a magnetic layer only, a magnetic layer having a multilayer structure, and a combination of a magnetic layer and a non-magnetic layer including at least one magnetic layer. The same applies to other than magnetic recording media.
Known layer configurations are possible. The coating width of the undercoat layer 6 and the both-sides precoat layer 11 which is a precoat liquid in the coating head and the width direction of the support is regulated in JP-A-62-152.
Known techniques such as Japanese Patent Laid-Open No. 563, Japanese Patent Laid-Open No. 62-241574, Japanese Patent Application No. 63-257289 can be used.

In the present embodiment, the undercoat layer 6 has a composition having an adhesive property, and the both edge precoat layers 11 applied to both ends of the undercoat layer 6 are those in which the both edge precoat layers are non-adhesive. It consists of As shown in FIGS. 1 and 2, the coating width b of the undercoat layer 6 having adhesiveness is smaller than the width a of the coating layer 7, and the width b of the undercoat layer 6 and the both edge precoats Sum of width 11 of layer 11 (a + 2d)
Is larger than the width a of the coating layer 7. In addition, as a matter of course, the width c of the support 1 is the width (a +
2d).

Further, as shown in FIG. 3, the coating layer 7 is applied while the undercoat layer 6 and the both edge precoat layers 11 are scraped off by the front edge 2. In this way, according to the coating method, since there is no uncoated portion of the precoat liquid in the area where the coating layer 7 is coated, the coating layer 7 can be applied even at its end portions as in the case shown in FIG. Can be applied well without rising. Moreover, since both edge precoat layers 11 exposed on both end sides of the magnetic layer 7 are non-adhesive, even if the magnetic recording medium is wound in a roll shape after the application, the magnetic recording medium is transported or stored. The trouble that the both edge precoat layers 11 adhere to the adjacent support 1 does not occur. The magnetic coating liquid is as follows.

The liquid mainly composed of an organic solvent used in the undercoating liquid in the present invention is, for example, an organic solvent alone such as toluene, methyl ethyl ketone, butyl acetate, cyclohexanone or a combination thereof, or a solute other than the organic solvent. May be contained in a small amount, but it is a low viscosity liquid having a viscosity of 20 cp or less, more preferably 5 cp or less. Then, a liquid obtained by dissolving an appropriate binder in this liquid can be the undercoat layer 6, and a liquid containing no binder can be the both edge precoat layers 11.

As the binder, conventionally known thermoplastic resins, thermosetting resins, reactive resins and mixtures thereof can be used. In the present embodiment, as the material of the coating head shown in FIG. 3, stainless steel, high speed steel, etc. can be used, but when high precision finishing is required, cemented carbide or ceramic is preferable. As the constitution of the magnetic coating liquid, those exemplified in the examples described later can be used, but the present invention is not limited thereto. Further, in the present embodiment, the single-layer coating device is described as shown in FIG. 3, but the present invention may be a coating device having two or more layers, for example, a configuration as shown in FIG. Although FIG. 4 is basically the same as the one shown in FIG. 3 described above, in this case, two coating layers can be simultaneously coated by the configuration in which the intermediate block 4 is arranged. That is, the slit 8A and the slit 8B
From this, different coating layers 7A and 7B are discharged respectively.

Further, ferromagnetic fine powder is used for the magnetic layer of the magnetic recording medium of the present invention. As the ferromagnetic fine powder, γ-
Fe ₂ O ₃ , Co-containing γ-Fe ₂ O ₃ , Fe ₃ O ₄ ,
Co-containing Fe ₃ O ₄ , γ-FeOx, Co-containing γ-
FeOx (X = 1.33~1.50), CrO 2, Co
-Ni-P alloy, Co-Ni-Fe-B alloy, Fe-N
Known ferromagnetic fine powders such as i-Zn alloy, Ni-Co alloy and Co-Ni-Fe alloy can be used. The particle size of these ferromagnetic fine powders is about 0.005 to 1 micron, The ratio of length / axis width is about 1/1 to 50/1.
The specific surface area of these ferromagnetic fine powders is 1 m ² / g
It is about 70 m ² / g. Also, as ferromagnetic fine powder,
Plate-like hexagonal barium ferrite can also be used. The particle size of barium ferrite is about 0.001 to 1 micron in diameter and the thickness is 1/2 to 1/20 of the diameter. Barium ferrite has a specific gravity of 4 to 6 g / cc and a specific surface of 1
m is ² / ^{g~70m 2} / g.

In the present invention, a binder is used in the magnetic layer together with the ferromagnetic fine powder. Examples of the binder to be used include conventionally known thermoplastic resins, thermosetting resins, reactive resins and mixtures thereof, as described above. The thermoplastic resin has a softening temperature of 150 ° C. or lower, an average molecular weight of 10,000 to 300,000, and a polymerization degree of about 50 to
2,000 or so, for example, vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride acrylonitrile copolymer, acrylic ester acrylonitrile copolymer, acrylic ester vinylidene chloride copolymer, acrylic Acid ester styrene copolymer, methacrylic acid ester acrylonitrile copolymer,
Methacrylic acid ester vinylidene chloride copolymer, methacrylic acid ester styrene copolymer, urethane elastomer, nylon-silicone resin, nitrocellulose-polyamide resin, polyvinyl fluoride, vinylidene chloride acrylonitrile copolymer, butadiene diacrylonitrile copolymer, Polyamide resin, polyvinyl butyral, cellulose derivative (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene butadiene copolymer, polyester resin, chlorovinyl ether acrylate copolymer, Amino resin,
Various synthetic rubber type thermoplastic resins and mixtures thereof are used.

As the thermosetting resin or the reactive resin,
The coating liquid has a molecular weight of 200,000 or less, and when the magnetic layer-forming composition is applied, dried and then heated, these resins undergo reactions such as condensation and addition to give an infinite molecular weight. It can be great. Further, among these resins, it is desirable that the resin does not soften or melt until the resin is thermally decomposed. Specifically, for example, phenol resin, epoxy resin, curable polyurethane resin, urea resin, melamine resin, alkyd resin, silicone resin, reactive acrylic resin, epoxy polyamide resin, nitrocellulose melamine resin, high molecular weight polyester resin and isocyanate. Prepolymer mixture, methacrylate copolymer and diisocyanate prepolymer mixture, polyester polyol and polyisocyanate mixture, urea formaldehyde resin, low molecular weight glycol / high molecular weight diol / triphenylmethane triisocyanate mixture, polyamide resin and There is a mixture of these.

The ferromagnetic fine powder dispersed in the binder, the solvent, the dispersant as an additive, the lubricant, the abrasive, the antistatic agent, the non-magnetic support and the like are the same as those conventionally used. To be done. Examples of the dispersant include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid and stearolic acid having 12 to 18 carbon atoms (R ₁ COOH, R ₁ is an alkyl or alkenyl group having 11 to 17 carbon atoms): Alkali metal (Li, Na, K, etc.) or alkaline earth metal (M) of the above fatty acid
g, Ca, Ba) metal soap: Fluorine-containing compound of the above fatty acid ester: Amide of the above fatty acid:
Polyalkylene oxide alkyl phosphate ester: Resinine: Trialkylpolyolefinoxy quaternary ammonium salt (alkyl has 1 to 5 carbon atoms, olefin has ethylene, propylene, etc.): etc. are used. In addition to these, higher alcohols having 12 or more carbon atoms, and other than these, sulfuric acid ester and the like can be used. As the lubricant, the above-mentioned dispersant is also effective, but dialkyl polysiloxane (alkyl has 1 to 5 carbon atoms), dialkoxy polysiloxane (alkoxy has 1 to 4 carbon atoms), monoalkyl monoalkoxy poly Silicone oil such as siloxane (alkyl has 1 to 5 carbons, alkoxy has 1 to 4 carbons), phenyl polysiloxane, fluoroalkyl polysiloxane (alkyl has 1 to 5 carbons), and conductive fine particles such as graphite. Powder: Inorganic fine powder such as molybdenum disulfide, tungsten dioxide: Plastic fine powder such as polyethylene, polypropylene, polyethylene vinyl chloride copolymer, polytetrafluoroethylene: α-
Olefin polymer: unsaturated aliphatic hydrocarbon that is liquid at room temperature (α-olefin in which a double bond is bonded to the terminal carbon, about 20 carbon atoms): monobasic fatty acid having 12 to 20 carbon atoms and 3 carbon atoms Fatty acid esters, fluorocarbons and the like composed of 12 monohydric alcohols can be used.

As the abrasive, fused alumina, silicon carbide, chromium oxide (Cr ₂ O ₃ ), corundum, artificial corundum, diamond, artificial diamond, garnet,
Emery (main component: corundum and magnetite) is used. Electrostatic fine powder such as carbon black and carbon black graft polymer as an antistatic agent: Natural surfactant such as saponin: Nonionic surfactant such as alkylene oxide type, glycerin type and glycidol type:
Cationic surfactants such as higher alkylamines, quaternary ammonium salts, pyridine and other heterocycles, phosphonium or sulfoniums: acidic such as carboxylic acid group, sulfonic acid group, phosphoric acid group, sulfuric acid ester group, phosphoric acid ester group Group-containing anionic surfactants: amphoteric surfactants such as amino acids, aminosulfonic acids, sulfuric acid or phosphoric acid esters of amino alcohols, etc. are used. As the organic solvent used as the coating solvent, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and other ketones: methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, glycol acetate monoethyl ether and other ester systems: benzene, toluene, Tar-based (aromatic hydrocarbons) such as xylene: chlorinated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin and dichlorobenzene.

The amount of solvent is 2-3 times that of the magnetic fine powder.
The dispersant is 0.5 to 2 with respect to 100 parts by weight of the binder.
0 parts by weight, the lubricant is 0.2 to 20 parts by weight, and the abrasive is 0.
5 to 20 parts by weight, 0.2 to 20 parts by weight of conductive fine powder used as an antistatic agent, and 0.1 to 10 parts by weight of a surfactant similarly used as an antistatic agent. The magnetic powder and the above-mentioned binder, dispersant, lubricant, abrasive, antistatic agent, solvent and the like are kneaded to form a magnetic paint.

Materials for the support on which these magnetic layers are provided include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, and vinyl-based materials such as polyvinyl chloride. Resin, polycarbonate, polyamide resin,
Examples include plastic films such as polysulfone, metal materials such as aluminum and copper, and ceramics such as glass. These supports may be previously subjected to pretreatments such as corona discharge treatment, plasma treatment, undercoating treatment, heat treatment, metal vapor deposition treatment and alkali treatment.
The support may be of any desired shape.

The present invention is not limited to the above embodiment as shown in the sectional view of FIG. 2, but may have the configuration shown in FIG. The coating in this case is a case where the undercoat layer 6 is not provided. Therefore, in the figure, the magnetic coating layer 7 has a single-layer structure. For example, in the same coating method using the coating apparatus shown in FIG. 3, the magnetic coating layer 7 is previously coated instead of the undercoat layer 6. And precoat layer 1 on both edges
It is also possible to employ a double-coating method in which the front edge 2 is scraped off together with 1. Further, instead of the undercoat layer 6, another magnetic coating layer may be applied to form a two-layer structure.

[0026]

As described above, according to the coating method of the present invention, there is no uncoated portion of the undercoating liquid in the area where the coating layer of the magnetic coating liquid or the like is coated, and at least both ends of the magnetic coating liquid. Since both edge precoat layers are formed in the part,
The coating layer can be satisfactorily coated without swelling as in the conventional case even at its end portion, and since both edge precoat layers exposed on both end sides of the magnetic layer are non-adhesive, it is possible that Even when the magnetic recording medium is wound into a roll and conveyed or stored, the trouble that the both edge precoat layers adhere to the adjacent support does not occur. Therefore, it is possible not only to improve the quality but also to increase the effective utilization rate of the coating layer and to improve the productivity as well as the productivity by eliminating the magnetic layer bulging portions which are generated at both edges of the undercoating liquid as in the conventional case. ..

[0027]

EXAMPLES The effects of the present invention can be further clarified by the following examples when applied to a magnetic recording medium. The magnetic coating liquid for a magnetic recording medium has the composition shown in Table 1.

[Table 1] (Composition of magnetic coating liquid) * γ-Fe ₂ O ₃ powder (acicular particles having an average particle diameter of 0.5 μ in the major axis direction, coercive force of 320 oersted) 300 parts by weight * Vinyl chloride vinyl acetate Copolymer (copolymerization ratio 87:13, degree of polymerization 400) 30 parts by weight * Conductive carbon 20 parts by weight * Polyamide resin (amine value 300) 15 parts by weight * Lecithin 6 parts by weight * Silicone oil (dimethyl polysiloxane) 3 Parts by weight * Xylol 300 parts by weight * Methyl isobutyl ketone 300 parts by weight * n-Butanol 100 parts by weight

After putting each component of the above composition into a pole mill and thoroughly mixing and dispersing, an epoxy resin (epoxy equivalent 5
No. 00) was added and uniformly mixed and dispersed to obtain a magnetic coating liquid (magnetic dispersion liquid). The precoat liquid used was methyl isobutyl ketone. The magnetic coating liquid was applied under the following conditions using the coating device described below.

Support material: polyethylene terephthalate film Thickness: 15μ Width: 500 mm Tension: 10 kg / full width Coating speed: 600 m / min Coating of undercoat layer and precoat layers on both edges 4.0 μm thick by bar coder coating method (Wet
State). The width b of the undercoat layer 6 is 470
mm, and the width d of the precoat layer 11 on both edges is 10 mm
Is. (A + 2d) is 490 mm.

Extruder With a construction based on the coating head shown in FIG. 3, the width of the front edge is 0.6 mm, the width of the back edge is 3 mm, and the step between the rear edge of the front edge and the tip of the back edge is 0.05 mm.
Is. The magnetic coating liquid was applied to a thickness of 15.0 μm, and its coating width a was set to 480 mm. As a result, when the both edge precoat layers 11 are not applied, that is, when the coating width of the undercoat liquid is 470 mm, a thick coating state occurs near the uncoated portion of the undercoat liquid (about 5 mm on each side). The entrained air reaches the magnetic layer coating part and does not become a product.

On the other hand, when the both edge precoat layers 11 are applied, thick coating is not generated at both ends of the magnetic coating layer 7, entrained air can be effectively removed and the coating solution can be spread well. There was no swelling, and good coating was possible. In addition, even after the application, the adhesion of the exposed portions of the both-sides precoat layer 11 did not occur at all.

[Brief description of drawings]

FIG. 1 is a plan view of a magnetic recording medium manufactured by a coating method of the present invention, showing a coating area on a support.

FIG. 2 is an enlarged cross-sectional view of a portion taken along the line AA in FIG.

FIG. 3 is a horizontal cross-sectional view of a main part of an extrusion type coating head for carrying out the present invention.

FIG. 4 is a transverse cross-sectional view of the main parts of another extrusion-type coating head for carrying out the present invention.

FIG. 5 is a cross-sectional view of a main part for explaining a conventional type coating method of an extrusion type coating head.

FIG. 6 is a transverse cross-sectional view of a magnetic recording medium shown in an enlarged scale to explain the drawbacks of the conventional coating method.

FIG. 7 is a lateral cross-sectional view of a magnetic recording medium enlarged to explain the drawbacks of the conventional coating method, showing a bulging portion generated at both widthwise edges of the magnetic layer. Is.

FIG. 8 is an enlarged cross-sectional view of a main part of another magnetic recording medium manufactured by the coating method of the present invention.

[Explanation of symbols]

 1 Support 2 Front Edge 3 Back Edge 4 Middle Block 5 Pocket 6 Undercoat Layer (Precoat Layer) 7 Coating Layer 8 Slit 9 Rear Edge of Front Edge 10 Front Edge of Back Edge 11 Precoat Layer a Magnetic Coating Area Width b width of undercoat layer c width of support d width of both edges precoat layer P bulging portion

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[Procedure amendment]

[Submission date] June 24, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

The applicant of the present invention has previously improved these characteristics to avoid streak failure and fluctuations in the coating film thickness due to nonuniformity of the thickness of the support, Young's modulus, etc. Further, when the coating solution passes through the slot. As a coating apparatus capable of reducing pressure loss, the coating apparatus described in Japanese Patent Application Laid-Open No. 63-20069 was filed. In Japanese Patent Laid-Open No. 630069/1988, as shown in FIG. 5, the magnetic coating liquid 7 is applied in a state of being sealed with a precoat layer 6 of an organic solvent or the like previously applied to the application surface of the support 1. , A front edge 2 located upstream with respect to the support moving direction, and a front edge 2 located downstream with respect to the support moving direction, the tip of which is stepped from the front edge and retracts in the direction opposite to the support. There is disclosed a coating apparatus for forming a coating layer on a support by an extrusion type head having a back edge 3 having a sharp tip. The precoat layer 6 is generally a so-called undercoat layer that improves the adhesion of the magnetic coating liquid 8 to the support 1. The magnetic coating liquid 7 is supplied to the pocket 5 from a liquid supply system (not shown), and the coating liquid 7 is stored in the pocket 5 and then pushed out to the slit 8.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

First, an organic solvent is applied to the coated surface of the support 1.
The liquid of the system is applied by a commonly used known coating device such as a gravure coater, a roll coater, a blade coater, and an extrusion coater, and this layer forms a coating layer of entrained air from the upstream side of the front edge. Penetration is prevented, a defect-free coating state is maintained, and high-speed coating characteristics are enhanced. The front edge 2 is located on the upstream side of the support 1 from the exit of the slit 8 and is formed so that the entire edge surface facing the support 1 bulges toward the support. A curved surface having a curvature is generally used as a form of bulging toward the support side, but the shape is not limited to this as long as entrainment of entrained air can be prevented.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

When the magnetic layer 7 is applied to the support 1 as shown in the enlarged cross section of the magnetic recording medium in FIGS. 6 and 7, the magnetic layer 7 is usually removed from the support 1. It is applied on the precoat layer 6 (undercoat layer) having adhesiveness to prevent peeling. Here, the when the magnetic coating layer 7 also narrows applying the coating width than the precoat layer 6 as shown in FIG. 5, which performs transport and storage by winding the magnetic recording medium in a roll after the coating fabric Therefore, there is a problem that the exposed portion 20 of the magnetic coating layer 7 adheres to the adjacent support 1 of the precoat layer 6. In order to solve this problem, conventionally, as shown in FIG. 7, the magnetic coating layer 7 is coated so as to cover the precoat layer 6.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

However, when the magnetic layer 7 is coated so as to cover the precoat layer 6, the cause of the occurrence is not clear, but the extensibility of the magnetic coating layer 7 at the portion where the precoat layer 6 is not wetted. Probably because the magnetic layer on both edges without the precoat layer 6 does not have a desired thickness, the magnetic layer bulging portion P that rises as shown in FIG. Has been found to be formed. Not only is it a product that is disqualified as a product at both edges of the support 1 as described above and the yield is reduced, but further, in a later step, for example, a calendering device and other various devices of the transport system are destroyed. There was a problem that caused a serious failure that could not be combined. Also, the precoat layer
Similarly, in the case where No. 6 has no adhesiveness, the magnetic layer bulging portion P of FIG. 7 is formed, and both end portions of the support 1 become unusable as a product, and there is a problem that the yield decreases.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

In the present embodiment, the undercoat layer 6 is mainly composed of
The composition has adhesiveness to the both edges, and the both edge precoat layers 11 applied to both end sides of the both edge precoat layers are non-adhesive. As shown in FIGS. 1 and 2, the coating width b of the undercoat layer 6 having adhesiveness is smaller than the width a of the coating layer 7, and the width b of the undercoat layer 6 and the both edge precoats Sum of width d of layer 11 (a + 2
d) is larger than the width a of the coating layer 7. The width c of the support 1 is naturally larger than the width (a + 2d) described above.

[Procedure Amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction content]

Further, as shown in FIG. 3, the coating layer 7 is applied while the undercoat layer 6 and the both edge precoat layers 11 are scraped off by the front edge 2. This
According to Una coating method, there is no non-coated portions of the pre-coating liquid in a range in which the coating layer 7 is applied, without even rise in the coating layer 7 is an end portion in the same manner as shown in FIG. 6 Can be applied well. Moreover, the magnetic layer 7
Since the both-ends precoat layer 11 exposed on both end sides is non-adhesive, even if the magnetic recording medium is wound into a roll and conveyed or stored after coating, the both-edges precoat layer is The trouble that 11 adheres to the adjacent support 1 does not occur. The magnetic coating liquid is as follows.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

The liquid mainly composed of an organic solvent used in the undercoating liquid in the present invention is, for example, an organic solvent alone such as toluene, methyl ethyl ketone, butyl acetate, cyclohexanone or a combination thereof, or a solute other than the organic solvent. May be contained in a small amount, but it is a low viscosity liquid having a viscosity of 20 cp or less, more preferably 5 cp or less. Then, a liquid obtained by dissolving a suitable binder in this liquid can be used as the undercoat layer 6 having adhesiveness, and a liquid containing no binder can be used as the both-sides precoat layer 11 and the non-adhesive bottom layer. It can be the coating layer 6 .

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

[0025] Further, the present invention is not limited to the above embodiment, as shown in cross-section view of FIG. 2, adhesion to the undercoat layer 6
If not, the configuration shown in FIG. 6 may be used as a result. This
In case of, the coating width of the undercoat layer 6 is widened to pre-coat both edge portions.
It may be used instead of layers.

[Procedure Amendment 9]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Delete

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikio Tomaru 2-12-1, Ogimachi, Odawara City, Kanagawa Fuji Photo Film Co., Ltd.

Claims (2)

[Claims] 1. A front edge located upstream of the support moving direction in a state of being liquid-sealed with an organic solvent-based liquid previously applied to the application surface of a flexible support,
An extrusion type coating head which is located on the downstream side with respect to the moving direction of the support, has its tip stepped back from the front edge and recedes in the direction opposite to the support, and has a back edge with a sharp tip. In the coating method for forming a predetermined coating layer on the support, both edge precoat layers formed on the lower layer side of the coating layer are non-adhesive, and both of them are applied when the coating layer is coated. A coating method, wherein the edge precoat layer is coated so as to be exposed from at least a widthwise edge of the coating layer. 2. The coating method according to claim 1, wherein when an undercoat layer having adhesiveness is formed on the lower layer side of the coating layer in addition to the both edge precoat layers, the undercoat layer is coated. The width is smaller than the width of the coating layer, and is applied such that the sum of the width of the undercoat layer and the width of both edge precoat layers applied to both ends of the undercoat layer is larger than the width of the coating layer. Then, the coating layer is coated while scraping off the undercoat layer and the both side edge precoat layers.