US3640752A - Coating method - Google Patents

Coating method Download PDF

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Publication number
US3640752A
US3640752A US869407*A US3640752DA US3640752A US 3640752 A US3640752 A US 3640752A US 3640752D A US3640752D A US 3640752DA US 3640752 A US3640752 A US 3640752A
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United States
Prior art keywords
coating
web
bridge
gas
applicator
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Expired - Lifetime
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US869407*A
Inventor
Mamoru Ishiwata
Huruya Akio
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Fujifilm Holdings Corp
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Fuji Photo Film Co Ltd
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
    • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
    • D21H23/22—Addition to the formed paper
    • D21H23/30—Pretreatment of the paper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
    • B05C5/02—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work the liquid or other fluent material being discharged through an outlet orifice by pressure, e.g. from an outlet device in contact or almost in contact, with the work
    • B05C5/0254—Coating heads with slot-shaped outlet
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H5/00—Special paper or cardboard not otherwise provided for
    • D21H5/0005—Processes or apparatus specially adapted for applying liquids or other fluent materials to finished paper or board, e.g. impregnating, coating
    • D21H5/0007—Pretreatment of paper to which liquids or other fluent materials are to be applied
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/74—Applying photosensitive compositions to the base; Drying processes therefor

Definitions

  • ABSTRACT In coating a coating composition on a web by a bridge of the coating composition between a coating applicator and the web, a gas blowing slot is formed at the side of the coating applicator into which the web enters to remove air or dust carried on the surface of the entering support and to provide a reduced pressure space at the back side of the bridge so that the bridge is maintained stable when the coating speed is increased.
  • This invention relates to an apparatus for applying a coating composition to one side of a continuously moving web.
  • a coating composition For applying a coating composition to one side of a continuously moving web. it is known to use a slide hopper, an extrusion hopper, a doctor blade, and the like as a coating applicator. When coating of a thin layer at high speed is carried out by one of these known means, a bridge or layer of the coating composition between the coating applicator and the support is broken by the shearing force of the moving support or by an air film carried by the surface of the moving support, and a uniform coafing cannot be obtained.
  • this invention provides for maintaining a lower pressure on the web inlet side of the coating applicator than on the outlet side to prevent breaking the bridge due to the air film carried on the surface of the sup port. Otherwise breaking of the coating bridge cannot be adequately prevented when the support is travelling at high speed.
  • the negative pressure on the inlet side of the applicator also eliminates the dust problem.
  • FIGS. 1 and 2 are schematic side sectional elevation views illustrating two embodiments of this invention.
  • a web 1 to be coated moves continuously, around a backup roller 2, facing a coating applicator 3 such as a slide hopper (FIG. 1) or an extrusion hopper (FIG. 2).
  • a coating applicator 3 such as a slide hopper (FIG. 1) or an extrusion hopper (FIG. 2).
  • a slot 4 is formed adjacent to a reduced pressure space 6 and is connected to a compressed gas chamber 5 for blowing a gas jet tangential to the web on roller 2 and opposite the direction of movement of the web. The clearance of the slot 4 may be controlled if necessary.
  • Reduced pressure space or chamber 6 is provided at the entrance of the web to the coating applicator and behind the coating bridge B.
  • a blower 7 is connected to the compressed gas chamber 5 for supplying a gas of a volume and pressure necessary to provide a gas jet from slot 4.
  • a gas exhausting means 9 having a capacity corresponding to the jet gas is connected to a suction chamber 8.
  • the clearance of slot 4 and the pressure of compressed gas chamber 5 are selected so that the speed of the gas jet at the outlet of the gas-blowing slot 4 may be maintained at a desired value (preferably to 0.5-1.0 mm. in clearance and more than 200 mm. water gauge in pressure respectively), t air film carried by the travelling support is removed by the gas jet from slot 4 and dust adhered to the surface of the support is also removed by the gas jet.
  • the pressure of space 6 is maintained at a suitable reduced value by the aspiration action of the gas jet, whereby the bridge B of the coating composition can be stabilized and the coating can be uniformly accomplished.
  • the gas generally used is air, although an inert gas, steam, solvent vapor or gas containing a small amount of surface active agent may be used, if necessary.
  • a surface active agent may be contained in the gas, in which case air on the surface of the web is replaced with the gas and the temperature and physico-chemical properties of the-web are changed so that the web surface may be endowed with antistatic property and the adhesion of the coating composition to the web is enhanced.
  • this invention provides an improved coating apparatus in which coating of a thin laiyer can be carned out at a high speed, the prob ems due to ust adhered to the surface of the web can be overcome, the adhesive force of a coating composition to the support can be enhanced and the coating bridge thereof between the support and device can be maintained stable to accomplish rapid and uniform coating.
  • gas-blowing slot is positioned adjacent the coating applicator at the web entrance side so that the gas jet is substantially tangential to the surface of the travelling support.
  • Dust carried on a travelling support or web is removed by the high speed gas jet blown from the gas blowing slot and at the same time the back side of the bridge of a coating composition forrned between a coating device and the travelling support is maintained at a lower pressure, which enables the uniform and stable coating of a thin layer with a high speed that has never been attained by conventional means.
  • a method for coating a web moving around a backup roll comprising a. applying a bridge of coating material to said web on said roll from an applicator disposed in close proximity to said roll b. directing a gas jet from said applicator tangentially against said web on said roll in a direction opposite to the direction of travel of said web at a point upstream from said bridge relative to the direction of travel of said web to provide a negative pressure on the back side of the bridge and on the surface of the web between said bridge and said point of gas jet application while simultaneously cleaning said web and providing a positive holddown force on said web.
  • a method as set forth in claim 1 further comprising c. adding a surface treatment agent to said gas jet to provide for simultaneous surface treatment of said web along with the application of said gas jet.

Abstract

In coating a coating composition on a web by a bridge of the coating composition between a coating applicator and the web, a gas blowing slot is formed at the side of the coating applicator into which the web enters to remove air or dust carried on the surface of the entering support and to provide a reduced pressure space at the back side of the bridge so that the bridge is maintained stable when the coating speed is increased.

Description

United States Patent Ishiwata et al.
[ 1 Feb. 8, 1972 [54] COATING METHOD [72] Inventors: Mamoru lfliiwata; l-luruya Aldo, both of Kanagawa, Japan [73] Assignee: Fuji Shashin Film Kabushiki Kaisha,
Kanagawa, Japan [22] Filed: June 24, 1969 [21] Appl. No.: 869,407
Related us. Application um [62] Division of Ser. No. 635,540, May 2, 1967, Pat. No.
[52] US. Cl ..ll7/47, 117/34, 117/119 [51} Int. Cl ..B44d 1/02 [58] Fieldot'Search ..ll7/47,34, 120, 119; 118/410 [56] References Cited UNlTED STATES PATENTS 2,681,294 6/1954 Beguin ..l17/34 2,761,791 9/1956 Russell ..1 17/34 2,795,522 6/1957 Johns 2,815,307 12/1957 Beck 3,206,323 9/1965 Miller et a1.
3,220,877 11/1965 Johnson ..1 17/120 Primary Examiner-William D. Martin Assistant Examinerwilliam R. Trenor AttorneySughrue, Rothwell, Mion, Zinn and Macpeak [57] ABSTRACT In coating a coating composition on a web by a bridge of the coating composition between a coating applicator and the web, a gas blowing slot is formed at the side of the coating applicator into which the web enters to remove air or dust carried on the surface of the entering support and to provide a reduced pressure space at the back side of the bridge so that the bridge is maintained stable when the coating speed is increased.
2 Claims, 2 Drawing PAIENTEDFEB 8 I972 N ORS MAMORU 'ISHIWATA AKIQ UYA COATINGMETHOD CROSS REFERENCE TO RELATED APPLICATION This application is a division of application Ser. No. 635,540 filed May 2, 1967 and now US. Pat. No. 3,503,370.
This invention relates to an apparatus for applying a coating composition to one side of a continuously moving web.
For applying a coating composition to one side of a continuously moving web. it is known to use a slide hopper, an extrusion hopper, a doctor blade, and the like as a coating applicator. When coating of a thin layer at high speed is carried out by one of these known means, a bridge or layer of the coating composition between the coating applicator and the support is broken by the shearing force of the moving support or by an air film carried by the surface of the moving support, and a uniform coafing cannot be obtained.
Moreover, with the prior art coating applicators, dust on the surface of the support attracted by electrostatic force are often transferred to the edge of a coating applicator when the support passes through the coating applicator, resulting in undesirable influence upon the coating bridge and the forming of stripes in the coating.
For overcoming these difiiculties, this invention provides for maintaining a lower pressure on the web inlet side of the coating applicator than on the outlet side to prevent breaking the bridge due to the air film carried on the surface of the sup port. Otherwise breaking of the coating bridge cannot be adequately prevented when the support is travelling at high speed. The negative pressure on the inlet side of the applicator also eliminates the dust problem.
The coating apparatus of the present invention will now be illustrated in the accompanying drawing, in which FIGS. 1 and 2 are schematic side sectional elevation views illustrating two embodiments of this invention.
Referring to the drawing, a web 1 to be coated moves continuously, around a backup roller 2, facing a coating applicator 3 such as a slide hopper (FIG. 1) or an extrusion hopper (FIG. 2).
A slot 4 is formed adjacent to a reduced pressure space 6 and is connected to a compressed gas chamber 5 for blowing a gas jet tangential to the web on roller 2 and opposite the direction of movement of the web. The clearance of the slot 4 may be controlled if necessary. Reduced pressure space or chamber 6 is provided at the entrance of the web to the coating applicator and behind the coating bridge B. A blower 7 is connected to the compressed gas chamber 5 for supplying a gas of a volume and pressure necessary to provide a gas jet from slot 4. In FIG. 1 a gas exhausting means 9 having a capacity corresponding to the jet gas is connected to a suction chamber 8.
In operation, if the clearance of slot 4 and the pressure of compressed gas chamber 5 are selected so that the speed of the gas jet at the outlet of the gas-blowing slot 4 may be maintained at a desired value (preferably to 0.5-1.0 mm. in clearance and more than 200 mm. water gauge in pressure respectively), t air film carried by the travelling support is removed by the gas jet from slot 4 and dust adhered to the surface of the support is also removed by the gas jet. At the same time, the pressure of space 6 is maintained at a suitable reduced value by the aspiration action of the gas jet, whereby the bridge B of the coating composition can be stabilized and the coating can be uniformly accomplished.
The gas generally used is air, although an inert gas, steam, solvent vapor or gas containing a small amount of surface active agent may be used, if necessary. A surface active agent may be contained in the gas, in which case air on the surface of the web is replaced with the gas and the temperature and physico-chemical properties of the-web are changed so that the web surface may be endowed with antistatic property and the adhesion of the coating composition to the web is enhanced.
As evident from the foregoing, this invention provides an improved coating apparatus in which coating of a thin laiyer can be carned out at a high speed, the prob ems due to ust adhered to the surface of the web can be overcome, the adhesive force of a coating composition to the support can be enhanced and the coating bridge thereof between the support and device can be maintained stable to accomplish rapid and uniform coating.
Further, the gas-blowing slot is positioned adjacent the coating applicator at the web entrance side so that the gas jet is substantially tangential to the surface of the travelling support.
When coating is conducted by using the improved coating apparatus of the present invention, the following advantages are obtained.
Dust carried on a travelling support or web is removed by the high speed gas jet blown from the gas blowing slot and at the same time the back side of the bridge of a coating composition forrned between a coating device and the travelling support is maintained at a lower pressure, which enables the uniform and stable coating of a thin layer with a high speed that has never been attained by conventional means.
The invention has been described above about a specific embodiment, but it should be understood that the invention is not limited to the form and construction of the illustrated apparatus.
What is claimed is:
l. A method for coating a web moving around a backup roll comprising a. applying a bridge of coating material to said web on said roll from an applicator disposed in close proximity to said roll b. directing a gas jet from said applicator tangentially against said web on said roll in a direction opposite to the direction of travel of said web at a point upstream from said bridge relative to the direction of travel of said web to provide a negative pressure on the back side of the bridge and on the surface of the web between said bridge and said point of gas jet application while simultaneously cleaning said web and providing a positive holddown force on said web.
2. A method as set forth in claim 1 further comprising c. adding a surface treatment agent to said gas jet to provide for simultaneous surface treatment of said web along with the application of said gas jet.

Claims (1)

  1. 2. A method as set forth in claim 1 further comprising c. adding a surface treatment agent to said gas jet to provide for simultaneous surface treatment of said web along with the application of said gas jet.
US869407*A 1966-05-02 1969-06-24 Coating method Expired - Lifetime US3640752A (en)

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JP2784566 1966-05-02
US86940769A 1969-06-24 1969-06-24

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3916043A (en) * 1971-11-15 1975-10-28 Eastman Kodak Co Method of coating a spliced web
US3928678A (en) * 1973-01-26 1975-12-23 Eastman Kodak Co Method and apparatus for coating a substrate
US3928679A (en) * 1973-01-26 1975-12-23 Eastman Kodak Co Method and apparatus for coating a multiple number of layers onto a substrate
US5192591A (en) * 1991-11-14 1993-03-09 Beloit Technologies, Inc. Short dwell coater apparatus
US5199991A (en) * 1991-04-19 1993-04-06 Beloit Technologies, Inc. Short dwell coater apparatus
EP0584674A2 (en) * 1992-08-22 1994-03-02 Hoechst Aktiengesellschaft Device for generating a vacuum
FR2697176A1 (en) * 1992-10-26 1994-04-29 Valmet Paper Machinery Inc Apparatus and method of jet coating
EP0606874A1 (en) * 1993-01-13 1994-07-20 Valmet Paper Machinery Inc. Method and assembly for preventing air entry between a moving material web and a roll
FR2723864A1 (en) * 1994-08-13 1996-03-01 Glyco Metall Werke METHOD AND DEVICE FOR PRODUCING LIQUID THIN FILMS IN THE FORM OF COATINGS OR SHEETS
US5607726A (en) * 1994-10-17 1997-03-04 E. I. Du Pont De Nemours And Company Process for the preparation of composite coatings with variable thickness
CN104162496A (en) * 2013-05-15 2014-11-26 上海和辉光电有限公司 Slit coater

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2681294A (en) * 1951-08-23 1954-06-15 Eastman Kodak Co Method of coating strip material
US2761791A (en) * 1955-02-23 1956-09-04 Eastman Kodak Co Method of multiple coating
US2795522A (en) * 1953-08-19 1957-06-11 Du Pont Processes of coating
US2815307A (en) * 1953-08-20 1957-12-03 Du Pont Processes for coating and drying photographic layers
US3206323A (en) * 1962-06-12 1965-09-14 Eastman Kodak Co Coating high viscosity liquids
US3220877A (en) * 1962-06-18 1965-11-30 Eastman Kodak Co Method of coating strip material

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2681294A (en) * 1951-08-23 1954-06-15 Eastman Kodak Co Method of coating strip material
US2795522A (en) * 1953-08-19 1957-06-11 Du Pont Processes of coating
US2815307A (en) * 1953-08-20 1957-12-03 Du Pont Processes for coating and drying photographic layers
US2761791A (en) * 1955-02-23 1956-09-04 Eastman Kodak Co Method of multiple coating
US3206323A (en) * 1962-06-12 1965-09-14 Eastman Kodak Co Coating high viscosity liquids
US3220877A (en) * 1962-06-18 1965-11-30 Eastman Kodak Co Method of coating strip material

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3916043A (en) * 1971-11-15 1975-10-28 Eastman Kodak Co Method of coating a spliced web
US3928678A (en) * 1973-01-26 1975-12-23 Eastman Kodak Co Method and apparatus for coating a substrate
US3928679A (en) * 1973-01-26 1975-12-23 Eastman Kodak Co Method and apparatus for coating a multiple number of layers onto a substrate
US5199991A (en) * 1991-04-19 1993-04-06 Beloit Technologies, Inc. Short dwell coater apparatus
US5192591A (en) * 1991-11-14 1993-03-09 Beloit Technologies, Inc. Short dwell coater apparatus
EP0584674A3 (en) * 1992-08-22 1994-03-16 Hoechst Aktiengesellschaft Device for generating a vacuum
EP0584674A2 (en) * 1992-08-22 1994-03-02 Hoechst Aktiengesellschaft Device for generating a vacuum
US5443638A (en) * 1992-08-22 1995-08-22 Hoechst Aktiengesellschaft Device for generating a subatmospheric pressure
FR2697176A1 (en) * 1992-10-26 1994-04-29 Valmet Paper Machinery Inc Apparatus and method of jet coating
EP0606874A1 (en) * 1993-01-13 1994-07-20 Valmet Paper Machinery Inc. Method and assembly for preventing air entry between a moving material web and a roll
FR2723864A1 (en) * 1994-08-13 1996-03-01 Glyco Metall Werke METHOD AND DEVICE FOR PRODUCING LIQUID THIN FILMS IN THE FORM OF COATINGS OR SHEETS
US5607726A (en) * 1994-10-17 1997-03-04 E. I. Du Pont De Nemours And Company Process for the preparation of composite coatings with variable thickness
CN104162496A (en) * 2013-05-15 2014-11-26 上海和辉光电有限公司 Slit coater

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