Vacuum assisted slot die coating techniques

• US 8,771,793 B2
• Filed: 04/15/2011
• Issued: 07/08/2014
• Est. Priority Date: 04/15/2011
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Inventors: Wilsey, Christopher D., Joseph, Abner D., Buccilli, Sergio
• Primary Examiner(s): Yuan, Dah-Wei D
• Assistant Examiner(s): Law, Nga Leung V
• Application Number:
  US13/088,078
• Publication Number:
  US 20120263879A1
• Time in Patent Office: 1,180 Days
• Field of Search: 427/294, 427/296, 427/402
• US Class Current: 427/294
• CPC Class Codes: B05C 11/10 Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material B05C1/0813, B05C5/0225, B05C17/002 and B05C19/06 take precedence
• CPC Class Codes: B05C 11/1005 responsive to condition of liquid or other fluent material already applied to the surface, e.g. coating thickness, weight or pattern
• CPC Class Codes: B05C 5/0254 Coating heads with slot-shaped outlet B05C5/0283 takes precedence
• CPC Class Codes: B05D 1/265 Extrusion coatings
• CPC Class Codes: B05D 3/0493 using vacuum
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52

Abstract

Systems, apparatuses, techniques and processes for applying a wet film to a substrate using a slot die are provided. In one form, the air pressure around at least a portion of the discharge end of the slot die is adjustable by the application of a vacuum force in order to control the width and thickness of the wet film being applied to the substrate. In one aspect of this form, the wet film is a narrow, continuous stripe of reagent material applied to a moving web of the substrate from which a plurality of test elements will be obtained. However, different forms and applications are also envisioned.

Claims

1. A method for applying a wet film to a substrate, comprising:

applying a coating material at a discharge rate about 2 ml/min to about 20 ml/min from a discharge end of a slot die onto a moving web of said substrate at a moving rate of about 10.0 m/min to about 45.0 m/min to form said wet film on said substrate, said wet film including a width and a thickness relative to said substrate, wherein said discharge end of said slot die comprises an upstream bar and a downstream bar each bar having an essentially planar land surface facing said moving web, and wherein a constant coating gap of about 40 μ

m to about 450 μ

m is maintained between said discharge end of said slot die and said moving web;

applying a vacuum force adjacent said discharge end of said slot die, wherein said vacuum force creates a pressure differential between an upstream side of said discharge end and a downstream side of said discharge end, and wherein said pressure differential is between about 1 inch of H₂0 and about 10 inches of H₂0; and

adjusting said vacuum force in real-time while applying said coating material to control said width and thickness of said wet film.

7. The method of claim 1, wherein said substrate is formed of a polymer material on which a plurality of electrode patterns is positioned.

8. The method of claim 7, which includes applying said coating material from said discharge end of said slot die over said electrode patterns to form said wet film on said electrode patterns.

9. The method of claim 1, wherein applying said vacuum force includes positioning a vacuum box adjacent said discharge end of said slot die, said vacuum box including a pair of vacuum outlets positioned opposite one another and upstream from said wet film.

10. The method of claim 1, wherein said coating gap is between about 40 μ

m and about 200 μ

m.

11. The method of claim 1, wherein said coating material includes a reagent for producing an electrochemical signal in the presence of a test analyte.

12. The method of claim 11, wherein said test analyte is glucose and said reagent includes at least one of an enzyme, co-enzyme and co-factor.

13. The method of claim 1, wherein said thickness of said wet film is between about 40 μ

m and about 100 μ

m.

14. The method of claim 1, which further includes drying said wet film to provide a dried layer of said coating material on said substrate, said dried layer of said coating material including a dried thickness between about 3 μ

m and about 20 μ

m.

15. The method of claim 1, wherein said discharge rate is about 2 ml/min to about 4 ml/min.

16. The method of claim 1, wherein said moving rate is about 10 m/min.

17. The method of claim 1, wherein said coating gap is about 190 μ

m.

18. The method of claim 1, wherein said pressure differential is about 2 inches of H₂0 to about 6 inches of H₂0.

2. A method for applying a wet film to a substrate, comprising:

applying a coating material at a discharge rate about 2 ml/min to about 20 ml/min from a discharge end of a slot die onto a moving web of said substrate at a moving rate of about 10.0 m/min to about 45.0 m/min to form said wet film on said substrate, said wet film including a width and a thickness relative to said substrate, wherein said discharge end of said slot die comprises an upstream bar and a downstream bar, each bar having an essentially planar land surface facing said moving web, and wherein a constant coating gap of about 40 μ

m to about 450 μ

m is maintained between said discharge end of said slot die and said moving web;

applying a vacuum force adjacent said discharge end of said slot die, wherein said vacuum force creates a pressure differential between an upstream side of said discharge end and a downstream side of said discharge end, and wherein said pressure differential is between about 1 inch of H₂0 and about 10 inches of H₂0;

adjusting said vacuum force in real-time while applying said coating material to control said width and thickness of said wet film; and

sensing said width of said wet film, and wherein adjusting said vacuum force is performed in response to determining said width corresponds to a value other than a predetermined value.

3. The method of claim 2, wherein said predetermined value is about 5 millimeters.

4. The method of claim 2, wherein said predetermined value is about 7 millimeters.

5. The method of claim 2, wherein said predetermined value is between about 4.7 millimeters and about 5.3 millimeters.

6. The method of claim 2, wherein said predetermined value is between about 6.7 millimeters and about 7.5 millimeters.