Method of multi-layer coating

• US 4,001,024 A
• Filed: 03/22/1976
• Issued: 01/04/1977
• Est. Priority Date: 03/22/1976
• Status: Expired due to Term

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Rozzi, Francis Armand, Dittman, Donald Allen
• Primary Examiner(s): Husack, Ralph
• Application Number:
  US05/668,883
• Time in Patent Office: 288 Days
• Field of Search: 427/411, 427/414, 427/434 A, 427/420, 427/402, 96/87 R, 96/85, 118/DIG. 4
• US Class Current: 430/531
• CPC Class Codes: B05C 5/007 Slide-hopper coaters, i.e. apparatus in which the liquid or other fluent material flows freely on an inclined surface before contacting the work
• CPC Class Codes: B05C 9/06 for applying two different liquids or other fluent materials, or the same liquid or other fluent material twice, to the same side of the work
• CPC Class Codes: G03C 1/74 Applying photosensitive compositions to the base; Drying processes therefor G03C1/496 takes precedence
• CPC Class Codes: G03C 2001/7481 Coating simultaneously multiple layers
• CPC Class Codes: G03C 2200/11 Blue-sensitive layer
• CPC Class Codes: G03C 2200/20 Colour paper

Abstract

The simultaneous high speed application of a plurality of liquid coating compositions to a moving web by the method of multi-layer bead coating is improved by coating the lowermost layer as a thin layer formed from a low viscosity coating composition and coating the layer immediately above the lowermost layer as a thicker layer of higher viscosity such that vortical action of the coating bead is confined to the lowermost layer and the layer immediately above it. By this means, intermixing of the coating composition forming the lowermost layer with the coating composition forming the layer immediately above it occurs, but all other layers are coated in discrete form. The method is especially useful in the manufacture of multi-layer photographic films and papers.

Claims

1. In a method of simultaneously applying a plurality of layers of liquid coating compositions to a moving web in which each of said compositions is fed into a coating bead which is maintained in bridging relationship between the surface of said web and a coating device spaced therefrom and the surface of said web is continuously moved across and in contact with said coating bead to simultaneously pick up all of said layers, the improvement wherein the speed of the web is at least 100 centimeters per second, the lowermost layer is thin and formed of a coating composition of low viscosity, and the layer immediately above the lowermost layer is thicker than the lowermost layer and formed of a coating composition of higher viscosity;

the thickness and viscosity of the lowermost layer and of the layer immediately above it being such that vortical of said coating bead is confined within the lowermost layer and the layer immediately above it, whereby interlayer mixing occurs between the lowermost layer and the layer immediately above it but all other layers are coated in distinct layer relationship.

2. In a method of manufacturing a photographic element by simultaneously applying a plurality of layers of liquid photographic coating compositions to a moving web of photographic support material in which each of said compositions is fed into a coating bead which is maintained in bridging relationship between the surface of said web and a coating device spaced therefrom and the surface of said web is continuously moved across and in contact with said coating bead to simultaneously pick up all of said layers, the improvement wherein the speed of the web is at least 100 centimeters per second, the lowermost layer is thin and formed of a coating composition of low viscosity, and the layer immediately above the lowermost layer is thicker than the lowermost layer and formed of a coating composition of higher viscosity;

the thickness and viscosity of the lowermost layer and of the layer immediately above it being such that vortical action of said coating bead is confined within the lowermost layer and the layer immediately above it, whereby interlayer mixing occurs between the lowermost layer and the layer immediately above it but all other layers are coated in distinct layer relationship.

3. The method of claim 2 wherein the wet coverage of the lowermost layer is in the range from about 2 to about 12 cubic centimeters of coating composition per square meter of web surface and the lowermost layer is formed from a coating composition with a viscosity in the range from about 1 to about 8 centipoises.

4. The method of claim 3 wherein the wet coverage of the layer immediately above the lowermost layer is in the range from about 15 to about 50 cubic centimeters of coating composition per square meter of web surface and the layer immediately above the lowermost layer is formed from a coating composition with a viscosity in the range from about 10 to about 100 centipoises.

5. The method of claim 2 wherein the wet coverage of the lowermost layer is in the range from about 5 to about 10 cubic centimeters of coating composition per square meter of web surface, the lowermost layer is formed from a coating composition with a viscosity in the range from about 3 to about 5 centipoises, the wet coverage of the layer immediately above the lowermost layer is in the range from about 20 to about 35 cubic centimeters of coating composition per square meter of web surface, and the layer immediately above the lowermost layer is formed from a coating composition with a viscosity in the range from about 30 to about 70 centipoises.

6. The method of claim 2 wherein the coating composition from which the lowermost layer is formed in a dilute gelatin solution.

7. The method of claim 2 wherein the coating composition from which the lowermost layer is formed is a dispersion of a coupler solvent in a hydrophilic colloid.

8. The method of claim 2 wherein the coating composition used to form the layer immediately above the lowermost layer is a gelatino/silver halide emulsion.

9. The method of claim 2 wherein the coating compositions used to form the lowermost layer and the layer immediately above it are each gelatino/silver halide emulsion but the composition used to form the lowermost layer is more dilute than that used to form the layer immediately above it.

10. The method of claim 2 wherein said support is a cellulose acetate support.

11. The method of claim 2 wherein said support is a polyester support.

12. The method of claim 2 wherein said support is a polymer-coated paper support.

13. The method of claim 2 wherein said support is a polyethylene-coated paper support.

14. The method of claim 2 wherein the coating composition forming the lowermost layer contains a surfactant.

15. The method of claim 2 wherein the lowermost layer is formed from a dilute gelatin solution having a viscosity in the range of from about 3 to about 5 centipoises coated at a wet coverage in the range from about 5 to about 10 cubic centimeters per square meter of web surface and the layer immediately above the lowermost layer is formed from a gelantino/silver halide emulsion having a viscosity in the range of from about 30 to about 70 centipoises coated at a wet coverage in the range from about 20 to about 35 cubic centimeters per square meter of web surface.