VACUUM ASSISTED SLOT DIE COATING TECHNIQUES

• US 20120263879A1
• Filed: 04/15/2011
• Published: 10/18/2012
• 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
• Granted Patent: US 8,771,793 B2
• Time in Patent Office: Days
• 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 from a discharge end of a slot die onto a moving web of said substrate to form said wet film on said substrate, said wet film including a width and a thickness relative to said substrate;

applying a vacuum force adjacent said discharge end of said slot die; and

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

2. The method of claim 1, which further includes 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.

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, which further includes maintaining a constant coating gap between said slot die and said moving web.

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

m and about 450 μ

m.

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

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

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

m and about 100 μ

m.

15. 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.

16. The method of claim 1, wherein applying said vacuum force creates a pressure differential between an upstream side of said discharge end and a downstream side of said discharge end.

17. An apparatus for applying a wet film to a substrate, comprising:

a slot die positionable adjacent to said substrate and including a discharge end from which a coating material is dischargeable onto said substrate to form said wet film; and

an air pressure regulation system, said system being operable to control width and thickness of said wet film relative to said substrate by adjusting air pressure adjacent said discharge end of said slot die as said coating material is discharged onto said substrate.

18. The apparatus of claim 17, wherein said air pressure regulation system includes an enclosure at least partially surrounding said discharge end of said slot die, and a vacuum source coupled with said enclosure.

19. The apparatus of claim 18, further comprising:

a sensor configured to determine said width of said wet film and provide a corresponding sensor signal representative of said width; and

a controller responsive to said sensor signal to adjust an amount of vacuum applied by said vacuum source to said enclosure when said sensor signal is representative of a width that corresponds to a value other than a predetermined value.

20. The apparatus of claim 19, wherein said predetermined value is between about 4.7 millimeters and about 5.3 millimeters.

21. The apparatus of claim 19, wherein said predetermined value is between about 6.7 millimeters and about 7.5 millimeters.

22. The apparatus of claim 18, wherein said vacuum source is coupled with said enclosure at a location upstream from said wet film.

23. The apparatus of claim 22, wherein said enclosure includes a pair of vacuum outlets positioned opposite one another.

24. The apparatus of claim 17, further comprising a moving web of said substrate, said web being formed of a polymer material on which a plurality of electrode patterns is positioned.

25. The apparatus of claim 24, wherein said slot die is positionable over said electrode patterns such that said coating material is dischargeable from said discharge end to form said wet film on said electrode patterns.

26. The apparatus of claim 17, wherein a coating gap in the range of about 40 μ

m to about 450 μ

m extends between said discharge end of said slot die and said substrate.

27. The apparatus of claim 17, further comprising a roller system operable to move said substrate relative to said slot die.

28. The apparatus of claim 17, further comprising a reservoir in fluid communication with said discharge end of said slot die, said reservoir containing a quantity of said coating material and said coating material including a reagent for producing an electrochemical signal in the presence of a test analyte.

29. The apparatus of claim 28, wherein said test analyte is glucose and said reagent includes at least one of an enzyme, co-enzyme and co-factor.

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

applying a coating material from a discharge end of a slot die onto said substrate to form said wet film on said substrate;

controlling a thickness of said wet film relative to said substrate by adjusting a pressure differential existing between an upstream side of said slot die and a downstream side of said slot die; and

maintaining a constant coating gap between said discharge end of said slot die and said substrate while controlling said thickness of said wet film.

31. The method of claim 30, wherein adjusting said pressure differential includes changing an amount of vacuum applied adjacent to said upstream side of said slot die.

32. The method of claim 30, wherein adjusting said pressure differential is performed in response to determining that a width of said wet film corresponds to a value other than a predetermined value.

33. The method of claim 32, wherein said predetermined value is between about 2.5 millimeters and 7.5 millimeters.

34. The method of claim 30, which further includes moving said substrate relative to said slot die, and maintaining a constant rate of movement of said substrate relative to said slot die while controlling said thickness of said wet film.

35. The method of claim 30, which further includes maintaining a constant flow rate of said coating material through said slot die while controlling said thickness of said wet film.

36. The method of claim 30, wherein said coating gap is between about 40 μ

m and about 450 μ

m.

37. The method of claim 30, wherein said coating material includes a reagent for producing an electrochemical signal in the presence of a test analyte.