EP0055985A2 - Technique pour augmenter l'uniformité d'un revêtement - Google Patents

Technique pour augmenter l'uniformité d'un revêtement Download PDF

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Publication number
EP0055985A2
EP0055985A2 EP82100014A EP82100014A EP0055985A2 EP 0055985 A2 EP0055985 A2 EP 0055985A2 EP 82100014 A EP82100014 A EP 82100014A EP 82100014 A EP82100014 A EP 82100014A EP 0055985 A2 EP0055985 A2 EP 0055985A2
Authority
EP
European Patent Office
Prior art keywords
coating
fluid
electrode
potential
web
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP82100014A
Other languages
German (de)
English (en)
Other versions
EP0055985B1 (fr
EP0055985A3 (en
Inventor
Semyon Kisler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Polaroid Corp
Original Assignee
Polaroid Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Polaroid Corp filed Critical Polaroid Corp
Publication of EP0055985A2 publication Critical patent/EP0055985A2/fr
Publication of EP0055985A3 publication Critical patent/EP0055985A3/en
Application granted granted Critical
Publication of EP0055985B1 publication Critical patent/EP0055985B1/fr
Expired legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/14—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by electrical means
    • 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
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/02—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface
    • B05C11/023—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface
    • 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
    • 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
    • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
    • G03C1/91—Photosensitive materials characterised by the base or auxiliary layers characterised by subbing layers or subbing means
    • G03C1/915—Photosensitive materials characterised by the base or auxiliary layers characterised by subbing layers or subbing means using mechanical or physical means therefor, e.g. corona

Definitions

  • the present invention relates to a method and apparatus for improving the uniformity of a coating material after it has been applied to a charge-retaining material, in general, and to such apparatus for improving the uniformity of a coating material that has been applied to a moving web of such material, in particular.
  • a nonuniform thickness coating applied to a moving web of such material would require considerably more drying time for drying the thicker portions of said nonuniform coating than would be required for drying the thinner portions of said nonuniform coating.
  • a temperature gradient that is optimum for drying said thicker coating portions is often excessive for optimum drying of said thinner coating portions. Drying time is usually the major factor limiting maximum production rates of many coated products.
  • many properties of photographic film such as sensitivity to light, color saturation, etc., for example, can be adversely affected when constructed with non- uniformly coated sheet materials.
  • One of the most effective coating thickness control techniques in present day use in the coating industry involves the employment of an electrostatic field to assist in the uniform deposition of coating materials on products to be coated.
  • an electrostatic field is established across the gap between the coating applicator and said backing roller by a high voltage power supply whose output terminals are connected between said applicator and said roller.
  • the electrostatic field in said coating causes a coating of uniform thickness to be deposited on a particular web surface.
  • the magnitude of the voltage established between said applicator and said roller is normally less than that required to generate corona, but often exceeds 3KV DC.
  • the electrostatic field causes a coating layer of uniform thickness to be deposited on tha material to be coated across a wide range of coating gaps without presenting an explosion or shock hazard to personnel, and without causing damage to or being subject to interruptions by imperfections in the material to be coated.
  • Electrostatic fields utilized in a manner such as those described above can greatly improve the thickness and/or surface uniformity of a layer of coating material.
  • the use of an electrostatic field for coating improvement purposes will often cause changes in coating properties such as surface tension and/or the residual electrostatic charge on the material to be coated, that can limit the extent to which coating uniformity can be improved with an electrostatic field.
  • Electrostatic charges present on a coated material, or coating fluid on a coating material having an electrostatic field related change in such properties as surface tension, etc., for whatever reason or reasons, can also limit the extent to which the uniformity of a coating material can be improved.
  • a method and apparatus are provided for substantially improving the coating uniformity of an electrically conductive coating material that has been applied to a material to be coated. After the coating material has been applied to said material and while said material is still in its fluid state, the coated material is subjected to an electric field established between a high voltage electrode and said electrically conductive coating material.
  • the present invention is directed to means for reducing the detrimental effects on coating uniformity produced by electrostatic charges remaining on a coated material.
  • These residual-type charges can be produced in several ways. In the coating industry, for example, electrostatic fields are employed to improve coating uniformity with a satisfactory though limited degree of success. While coating uniformity is substantially improved with an electrostatic field, the residual electrostatic charges remaining on the coated material limit the extent of said improvement.
  • Electrostatically assisted coating apparatus typical of that in present use in the coating industry is schematically illustrated in Fig. 1.
  • numeral 10 generally indicates coating apparatus employing conventional electrostatic coating-gap assist apparatus constructed in accordance with the teaching of the prior art.
  • Web support or backing roller 12 is cylindrically shaped, is electrically conductive and is mounted for rotation about backing roller axis 14.
  • Coating applicator 16 is mounted in a fixed position with respect to backing roller 12 and is spaced from said roller 12 by a distance or gap 18.
  • High voltage power supply 20 having a DC voltage across its output terminals that is often in the neighborhood of several thousand volts, has said output terminals connected between backing roller 12 and applicator 16 through paths 22 and 24, respectively. Because the coating fluid supplied by applicator 16 is electrically conductive, it often maintains said applicator 16 at or near ground potential through a coating-fluid-supplying conduit (not shown), the high voltage terminal of power supply 20 is necessarily connected to said roller 12 and the low voltage terminal of said supply 20 is connected to said grounded applicator 16.
  • electrostatic field 26 is produced in coating gap 18 between high potential backing roller 12 and grounded applicator 16.
  • charge-retaining web 28 is moved in direction 30 through gap 18 by drive means (not shown)
  • said web 28 is electrostatically charged by orienting its dipoles (such as by orienting dipoles 31) by said electrostatic field 26.
  • Electrostatic charges produced on web 28 by electrostatic field 26 cause fluid 32 flowing from applicator 16 into coating gap 18 to be attracted toward and uniformly deposited on moving web 28.
  • This portion of the coating material 32 is sometimes referred to as a coating fluid bead and is designated numeral 34 in prior art Fig. 1.
  • the surface of web 28 normally moves faster than the rate at which coating fluid 32 flows onto said web 28 surface. This being so, as web 28 and fluid 32 in the form of bead 34 are brought into contact with one another, the faster moving web 28 pulls and thereby stretches said fluid 32 causing the thickness of coating fluid 32 to be reduced to a desired intermediate level.
  • electrostatic field 26 changes properties of coating fluid 32 such as surface tension, thereby allowing said fluid 32 to be stretched to a greater degree and over a larger gap between web 28 and applicator 16 without losing (breaking) bead 34 than would be possible if electrostatic gap-assisting field 26 were not present.
  • gap 18 in Fig. 1 must be large enough to accommodate such things as web splices and foreign matter so that such splices or matter do not come into contact with applicator 16 and thereby adversely affect web coating quality.
  • FIG. 2 Another type of electrostatically assisted coating apparatus that is the subject of my above-cited copending patent application, is schematically illustrated in Fig. 2.
  • numeral 36 generally indicated web coating apparatus employing a precharged web coating technique.
  • web support or backing roller 38 is cylindrically shaped, is electrically conductive, is mounted for rotation about backing roller axis 40 and for safety purposes is electrically grounded through path 41 to prevent said roller from operating like a high potential producing Van de Graaff generator.
  • Coating applicator 42 is mounted in a fixed position with respect to backing roller 38 and is spaced from said roller 38 by distance or gap 44.
  • Grounded web support or backing roller 46 is cylindrically shaped, is electrically conductive and grounded, and is mounted for rotation about backing roller axis 48.
  • Conductive bristle brush 50 is mounted in a fixed position with respect to and has the free ends of its bristles pointed toward and spaced from said grounded backing roller 46.
  • DC power supply 52 has its high voltage output terminal connected to one end of each of the bristles of said conductive bristle brush 50 through path 54 and has its low voltage output terminal connected to grounded backing roller 46 through path 56 and common ground points 58.
  • FIG. 3 numeral 70 generally indicated web coating apparatus employing coating uniformity improvement means constructed in accordance with the present invention.
  • web support or backing roller 72 is cylindrically shaped, is electrically conductive and is mounted for rotation about backing roller axis 74.
  • Backing roller 72 may or may not be grounded depending upon whether or not an electrostatically assisted coating technique is employed and if employed, the particular type of electrostatic assist technique selected.
  • Coating applicator 76 is electrically grounded through either the coating fluid conduit (not shown) or through patz 77, is mounted in a fixed position with respect to backing roller 72 and is spaced from said roller 72' by distance or gap 78.
  • Conductive bristle brush 82 is mounted in a fixed position with respect to, and has the free ends of its bristles spaced from surface 84 of said web 80.
  • DC power supply 86 has its high voltage output terminal connected to one end of each of the bristles of said conductive brush 82 through path 88 and has its low voltage output terminal electrically grounded through path 90.
  • coating fluid 94 is deposited on said web 80 by coating fluid applicator 76.
  • the coating process may or may not be assisted by an electrostatic field. However, under normal conditions a substantially larger residual electrostatic charge and substantially greater change in coating fluid properties will be present in a coated material and its coating, respectively, when an electrostatic field is employed in a web coating process than when such a field is not so employed.
  • Fig. 4 is an enlarged detail of energized conductive'bristle brush 82 and a portion of coated web 80 immediately adjacent said brush 82, said coated web 80 is moved in direction 92 through the electrostatic field established between said brush 82 and coating fluid 94 on said web 80.
  • surface 96 of coating fluid 94 is relatively uneven or nonuniform after it has been applied to web 80 but before coating fluid 94 with its said nonuniform surface 96 is subjected to the electrostatic field of brush 82.
  • the magnitude and polarity of this electrostatic field is normally established empirically and is primarily determined by the type of material to be coated and the type coating material to be applied.
  • the web coating uniformity improvement apparatus of the present invention employs the electrically conductive coating material itself as a ground or electrically conductive reference member in conjunction with a conductive bristle brush to establish the desired charge-controlling electrostatic field.
  • This use of coating fluid 94 is necessary because the coating fluid is necessarily in its fluid state when it is subjected to the electrostatic field of brush 82 for. coating improvement purposes and if an alternate reference or ground member were employed it would adversely effect coating fluid thickness and surface quality if it were placed in contact with the coating fluid while said fluid was still in its said fluid state.
  • brush 82 When a potential difference is established between brush 82 and coating fluid 94 in, for example, Fig. 3, said brush 82 is sometimes referred to herein as an electrode. Also the term "electrostatic field" employed herein means one species of electric field.
EP19820100014 1981-01-05 1982-01-04 Technique pour augmenter l'uniformité d'un revêtement Expired EP0055985B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US22233481A 1981-01-05 1981-01-05
US222334 1981-01-05

Publications (3)

Publication Number Publication Date
EP0055985A2 true EP0055985A2 (fr) 1982-07-14
EP0055985A3 EP0055985A3 (en) 1983-02-02
EP0055985B1 EP0055985B1 (fr) 1987-04-15

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19820100014 Expired EP0055985B1 (fr) 1981-01-05 1982-01-04 Technique pour augmenter l'uniformité d'un revêtement

Country Status (4)

Country Link
EP (1) EP0055985B1 (fr)
JP (1) JPS57167751A (fr)
CA (1) CA1193226A (fr)
DE (1) DE3276052D1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0055983A2 (fr) * 1981-01-05 1982-07-14 Polaroid Corporation Aire de revêtement assistée électrostatiquement
WO1996009124A1 (fr) * 1994-09-22 1996-03-28 Minnesota Mining And Manufacturing Company Systeme electrostatique de regulation de l'ecoulement d'un fluide apres son application sur un substrat
EP0809152A2 (fr) * 1996-03-26 1997-11-26 Mitsubishi Chemical Corporation Procédé de fabrication d'un photorécepteur électrophotographique
US6368675B1 (en) 2000-04-06 2002-04-09 3M Innovative Properties Company Electrostatically assisted coating method and apparatus with focused electrode field
US6475572B2 (en) 2000-04-06 2002-11-05 3M Innovative Properties Company Electrostatically assisted coating method with focused web-borne charges

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4899492B2 (ja) * 2006-01-20 2012-03-21 富士ゼロックス株式会社 無端ベルトの製造方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1166500A (en) * 1965-12-23 1969-10-08 Fuji Photo Film Co Ltd Process and Apparatus for Coating a Moving Support
US3671806A (en) * 1970-11-20 1972-06-20 Eastman Kodak Co Method of and apparatus for applying an electrical charge to a moving sheet of flexible material

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1166500A (en) * 1965-12-23 1969-10-08 Fuji Photo Film Co Ltd Process and Apparatus for Coating a Moving Support
US3671806A (en) * 1970-11-20 1972-06-20 Eastman Kodak Co Method of and apparatus for applying an electrical charge to a moving sheet of flexible material

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0055983A2 (fr) * 1981-01-05 1982-07-14 Polaroid Corporation Aire de revêtement assistée électrostatiquement
EP0055983B1 (fr) * 1981-01-05 1987-05-06 Polaroid Corporation Aire de revêtement assistée électrostatiquement
WO1996009124A1 (fr) * 1994-09-22 1996-03-28 Minnesota Mining And Manufacturing Company Systeme electrostatique de regulation de l'ecoulement d'un fluide apres son application sur un substrat
US5688563A (en) * 1994-09-22 1997-11-18 Minnesota Mining And Manufacturing Company Electrostatic system for controlling the flow of a fluid after being coated onto a substrate
EP0809152A2 (fr) * 1996-03-26 1997-11-26 Mitsubishi Chemical Corporation Procédé de fabrication d'un photorécepteur électrophotographique
EP0809152A3 (fr) * 1996-03-26 1998-02-04 Mitsubishi Chemical Corporation Procédé de fabrication d'un photorécepteur électrophotographique
US6368675B1 (en) 2000-04-06 2002-04-09 3M Innovative Properties Company Electrostatically assisted coating method and apparatus with focused electrode field
US6475572B2 (en) 2000-04-06 2002-11-05 3M Innovative Properties Company Electrostatically assisted coating method with focused web-borne charges
US6666918B2 (en) 2000-04-06 2003-12-23 3M Innovative Properties Company Electrostatically assisted coating apparatus with focused web charge field
US6716286B2 (en) 2000-04-06 2004-04-06 3M Innovative Properties Company Electrostatically assisted coating method and apparatus with focused electrode field

Also Published As

Publication number Publication date
EP0055985B1 (fr) 1987-04-15
EP0055985A3 (en) 1983-02-02
DE3276052D1 (en) 1987-05-21
CA1193226A (fr) 1985-09-10
JPS57167751A (en) 1982-10-15
JPH0135703B2 (fr) 1989-07-26

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