Method and apparatus for selectively demetallizing a metallized film

• US 5,061,837 A
• Filed: 05/02/1989
• Issued: 10/29/1991
• Est. Priority Date: 05/02/1989
• Status: Expired due to Fees

• Current Assignee: Webex Holdings Subsidiary Incorporated (Maxcess International Holding Corp.)
• Original Assignee: WebEx Communications (Cisco Systems, Inc.)
• Inventors: Gilbert, William B., Roberts, Jack V., Walker, Alfred J.
• Primary Examiner(s): Evans, Geoffrey S.
• Application Number:
  US07/346,062
• Time in Patent Office: 910 Days
• Field of Search: 219/383, 219/384, 219/68, 219/69.17, 219/10.55 E, 219/10.55 M, 346/162, 346/163, 346/164, 156/627, 430/318, 426/107, 426/113, 426/124, 426/126, 29/25.42
• US Class Current: 219/68
• CPC Class Codes: B23K 11/22 Severing by resistance heating
• CPC Class Codes: B65D 2581/3467 Microwave reactive layer shaped by delamination, demetallizing or embossing
• CPC Class Codes: B65D 81/3446 specially adapted to be heated by microwaves
• CPC Class Codes: H01G 13/06 with provision for removing metal surfaces
• CPC Class Codes: Y10T 29/435 Solid dielectric type

Abstract

A method and apparatus for selectively demetallizing a metallized film whereby the metallized web is selectively demetallized by bringing the web into contact with two electrodes, one of which contacts a greater surface area of the web than the other, and maintaining an electrical potential difference between the two electrodes. Preferably, the electrodes comprise rollers, one of which may be provided with a predetermined pattern. The potential difference between the respective electrodes can be controlled to effect selected demetalization of predetermined desired regions of the web or to vary the extent of demetalization from a desired region. The web material can subsequently be used as microwavable packaging material.

Claims

1. A method of selectively demetallizing a metallized web moving along a web path, comprising the steps of:

selectively generating a potential difference between first and second electrodes disposed spaced apart along said web path, said second electrode comprising a roller extending transversely across said path;

effecting a first electrical contact of relatively large area between said moving web and said first electrode;

effecting a second electrical contact between said web and said second electrode, said second electrical contact being of an area less than the area of said first electrical contact, producing a high density current to demetallize said web at said second electrical contact; and

,

controllably varying the magnitude of the potential difference to control the degree of demetallization of said web.

2. The method of claim 1 wherein said

controllably varying step comprises selectively turning said potential differential on and off.

3. The method of claim 1 wherein said controllably varying step comprises varying the magnitude of said potential difference in accordance with a predetermined pattern.

4. A method of selectively demetallizing a metallized web moving along a web path, comprising the steps of:

selectively generating a potential difference between first and second electrodes disposed spaced apart along said web path, said second electrode comprising a roller extending transversely across said path;

effecting a first electrical contact of relatively large area between said moving web and said first electrode;

effecting a second electrical contact between said web and said second electrode, said second electrical contact being of an area less than the area of said first electrical contact, producing a high density current to demetallize said web at said second electrical contact; and

,

removing metal deposited on said second electrode.

5. An apparatus for demetallizing a metallized web moving along a path of the type comprising first and second electrodes, means for generating potential difference between said electrodes, and means for establishing an electrical connection between the electrodes and the metallized web, improved wherein:

said first electrode effects a first predetermined area of contact with said web;

said second electrode includes a curved portion and effects a second predetermined area of contact with said web, said second predetermined area being less than said first predetermined area;

said second electrode manifests a predetermined pattern and is formed, at least in part, of aluminum and portions thereof are anodized, in accordance with said pattern, to render such portions non-conductive, whereby said metallized web is demetallized in accordance with said pattern; and

,

said means for establishing an electrical connection between said electrodes and said web includes means for effecting contact between said web and means for forming a curved portion in said web path oppositely directed from the curved portion of said second electrode and biasing said web against said curved portion of said second electrode, in said curved portion of said web path.

6. An apparatus for demetallizing a metallized web moving along a path of the type comprising first and second electrodes, means for generating a potential difference between said electrodes, and means for establishing an electrical connection between the electrodes and the metallized web, improved wherein:

said first electrode effects a first predetermined area of contact with said web;

said second electrode includes a curved portion and effects a second predetermined area of contact with said web, said second predetermined area being less than said first predetermined area;

said second electrode manifests a predetermined pattern and portions of said second electrode in accordance with said pattern are plated with a conductive material, whereby said metallized web is demetallized in accordance with said pattern; and

,

said means for establishing an electrical connection between said electrodes and said web includes means for effecting contact between said web and means for forming a curved portion in said web path oppositely directed from the curved portion of said second electrode and biasing said web against said curved portion of said second electrode, in said curved portion of said web path.

7. The apparatus of claim 6 wherein portions of said second electrode in accordance with said pattern are plated with nickel.

8. An apparatus for demetallizing a metallized web moving along a path, said apparatus being of the type comprising first and second electrodes, means for generating a potential difference between said electrodes, and means for establishing an electrical connection between the electrodes and the metallized web, improved wherein said means for generating a potential difference includes means for selectively effecting partial demetallization of areas of said web by varying the magnitude of the potential in accordance with a predetermined pattern.

9. The apparatus of claim 8 wherein at least one of said electrodes comprises a roller.

10. An apparatus for demetallizing a metallized web moving along a path of the type comprising first and second electrodes, means for generating a potential difference between said electrodes, and means for establishing an electrical contact between said electrodes and said metallized web, improved wherein:

each electrode comprises a roller; and

said means for establishing contact includes;

means for establishing a relatively large area of contact between said metallized web and said first electrode;

means for establishing a relatively small area of contact along a line transverse to said web path between said metallized web and said second electrode to produce a high density current between said web and said second electrode; and

,

means for removing metal deposited on the second roller.

11. Apparatus for selectively demetallizing a metallized web moving along a web path, comprising:

a first conductive roller at a first electrical potential;

a second conductive roller at a second electrical potential;

a first nip roller;

a second nip roller;

said first and second conductive rollers being spaced apart proximate said web, said first nip roller being disposed relative to said first roller to interact with said first roller;

said first conductive roller and said first nip roller being disposed such that said metallized web wraps around a substantial portion of said first conductive roller to thereby establish a relatively large area of electrical contact;

said second conductive roller and said second nip roller being disposed to effect electrical contact between said second conductive roller and said metallized web along a line transverse to the direction of web movement.

12. An apparatus for demetallizing a metallized web moving along a path, said apparatus being of the type comprising first and second electrodes, means for generating a potential deference between said electrodes, and means for establishing an electrical connection between the electrodes and the metallized web, improved wherein:

said second electrode manifests a predetermined pattern, whereby metallized web is demetallized in accordance with said a pattern; and

said second electrode is formed, at least in part, of aluminum and portions thereof are anodized, in accordance with said pattern, to render such portions nonconductive.

13. A method of selectively demetallizing a metallized web moving along a web path, comprising the steps of:

selectively generating a potential difference between first and second electrodes disposed spaced apart along said web path, said second electrode comprising a roller extending transversely across said path;

effecting a first electrical contact of relatively large are between said moving web and said first electrode;

effecting a second electrical contact between said web and said second electrode, said second electrical contact being of an area less than the area of said first electrical contact, producing a high density current to demetallize said web at said second electrical contact; and

,

varying said potential difference to selectively vary the percentage demetallization and create partially demetallized areas on said web.

14. A method of selectively demetallizing a metallized web moving along a web path, comprising the steps of:

selectively generating a potential difference between first and second electrodes disposed spaced apart along said web path, said second electrode comprising a roller extending transversely across said path;

effecting a first electrical contact of relatively large are between said moving web and said first electrode;

effecting a second electrical contact between said web and said second electrode, said second electrical contact being of an area less than the area of said first electrical contact, producing a high density current to demetallize said web at said second electrical contact;

selectively generating a potential difference between third and fourth electrodes disposed along said web path;

effecting a third electrical contact having a relatively large area between said moving web and said third electrode; and

effecting a fourth electrical contact between said web and said fourth electrode, said fourth electrical connection having a relatively small area, producing a high density current to demetallize said web at said fourth electrode.

15. The method of claim 14 wherein:

said second electrode manifests a first part of a composite pattern;

said fourth electrode manifests a second part of said composite pattern;

and further including the steps of;

routing said web to said first and second electrodes and to said third and fourth electrodes in sequence;

effecting demetallization of said web in accordance with said first part of said pattern at said second electrode; and

effecting demetallization of said web in accordance with said second part of said pattern at said fourth electrode.

16. The method of claim 15 wherein:

said first part of said pattern comprises a portion aligned with the direction of movement of said web along said path; and

said second part of said pattern comprises a portion transverse to the direction of movement of said web along said path.

17. The method of claim 14 wherein:

said selectively generating a potential difference between first and second electrodes step comprises generating a potential of a first magnitude; and

said selectively generating a potential difference between third and fourth electrodes step comprises generating a potential of a second magnitude.

18. The method of claim 14 wherein:

said second electrode manifests a first pattern;

said fourth electrode manifests a second pattern including at least one element in common with said first pattern;

and including the step of;

effecting further demetallization of said web in accordance with said element common to said first and second patterns at said fourth electrode to provide a composite pattern with elements of differing optical density.

20. The method of claim 14 wherein said predetermined optical density is in the range of 0.18 to 0.29.

19. A method for making microwavable packaging material comprising a substrate having metallized areas of different optical density from a metallized substrate, said method comprising the steps of:

selectively effecting electrical contact between said metallized substrate and a set of respective electrodes;

generating a potential difference between said respective electrodes of said set of a magnitude to partially demetallize to a predetermined optical density selected areas of said substrate at one of said electrodes.

21. The method of claim 19 wherein said microwavable packaging material is adapted to contain foodstuff in the vicinity of said selected partially demetallized areas and said step of generating a potential difference is carried out such that the predetermined optical density obtained is sufficient to effect browning of said foodstuff upon microwaving a package made of said microwavable packaging material containing said foodstuff at said selected areas.

22. The method of claim 21 further comprising the step of varying the optical density of selected areas of said substrate by varying the magnitude of said potential difference to vary the extent of the partial demetallization of said selected areas of said substrate.

23. The method of claim 21 wherein:

said substrate comprises a metallized film web;

at least one of said electrodes comprises a roller; and

said selectively effecting electrical contact step comprises effecting a line contact between the metallization on said film and said roller as said web moves along a predetermined path.

24. The method of claim 21 further comprising the step of:

varying the optical density of selected areas of said substrate by selectively effecting electrical contact between said metallized substrate and the respective electrodes of a second set of respective electrodes to at least partially demetallize such selected areas of said substrate.

25. The method of claim 24 further comprising the step of varying the magnitude of the potential difference between the electrodes of said second set.

26. The method of claim 24 wherein:

one of said first mentioned set of electrodes manifests a first part of a composite pattern;

one of said second set of electrodes manifests a second part of said composite pattern;

and comprising the steps of;

routing said substrate along a path to said first mentioned and second set of electrode in sequence;

effecting demetallization of said metallized substrate in accordance with said first part of said pattern at said first mentioned set electrode; and

effecting demetallization of said metallized substrate in accordance with said second part of said pattern at said second set electrode.

27. The method of claim 26 wherein:

said first pat of said pattern comprises a portion aligned with the direction of movement of said metallized substrate along said path; and

said second part of said pattern comprises a portion transverse to the direction of movement of said metallized substrate along said path.

28. The method of claim 24 wherein:

said generating a potential difference between the respective electrodes of said first mentioned set step comprises generating a potential of a first magnitude; and

said generating a potential difference between the respective electrodes of said second set step comprises generating a potential of a second magnitude.

29. The method of claim 24 wherein:

one of said first mentioned set of electrodes manifests a first pattern;

one of said second set of electrodes manifests a second pattern including at least one element in common with said first pattern;

and comprising the steps of;

routing said substrate along a path to said first mentioned and said second set of electrodes in sequence; and

effecting further demetallization of said metallized substrate in accordance with said element common to said first and second patterns at said second set electrode to provide a composite pattern with elements of differing optical density.

30. An apparatus for making microwavable packaging material, comprising:

means for routing a metallized substrate along a path;

first and second electrodes disposed in spaced relation along said path;

means for selectively establishing a potential difference between said first and second electrodes; and

,

means for establishing an electrical contact between said metallized substrate and said first and second electrode to partially demetallize areas on said substrate, such that each of said substrate areas manifest a desired optical density.

31. The apparatus of claim 30 wherein said second electrode includes conductive portions and non-conductive portions corresponding to a first demetallization pattern.

32. The apparatus of claim 31 further including:

third and fourth electrodes disposed along said path in spaced relation to said first and second electrodes, said fourth electrode bearing a second demetallization pattern;

means for selectively establishing a potential difference between said third and fourth electrodes; and

means for establishing an electrical contact between said substrate and said third and fourth electrodes to at least partially demetallize said substrate in accordance with said second demtallization pattern.

33. The apparatus of claim 32 wherein said first demetallizaton pattern includes a plurality of elements and said second demetallization pattern includes at least one element disposed in accordance with an element of said first demetallization pattern, such that partially demetallized areas of different optical densities are formed on said substrate.

34. A method of making packaging for microwavable foodstuffs, said packaging material having predetermined regions of different optical density, said method comprising the steps of:

conveying a metallized web along a web path, into electrical contact with first and second electrodes disposed in spaced relation along said web path, said second electrode bearing a desired demetallizaton pattern;

selectively generating a potential difference between said fist and second electrodes; and

,

demetallizing said web in accordance with said desired demetallization pattern by effecting a relatively high density current flow between said second electrode and said web and partially demetallizing portions of said web to form partially demetallized areas of different optical densities.

35. A method for making microwavable packaging material comprising a substrate having metallized areas of different optical density from a metallized substrate, said method comprising the steps of:

routing said substrate along a path to first and second sets of electrodes in sequence;

selectively effecting electrical contact between said metallized substrate and said first set of respective electrodes, one of said first set of electrodes manifesting a first part of a composite pattern, said first part of said pattern comprising a portion aligned with the direction of movement of said metallized substrate along said path; and

generating a potential difference between said respective electrodes of said first set of a magnitude to at least partially demetallize selected areas of said substrate in accordance with said pattern first parts;

selectively effecting electrical contact between said metallized substrate and the respective electrodes of a second set of respective electrodes, one of said second set of electrodes manifesting a second part of said composite pattern, said second part of said pattern comprising a portion transverse to the direction of movement of said metallized substrate along said path;

generating a potential difference between said respective electrodes of said second set of a magnitude to at least partially demetallize selected areas of said substrate in accordance with said pattern second part.

36. A method for making microwavable packaging material comprising a substrate having metallized areas of different optical density from a metallized substrate, said method comprising the steps of:

selectively effecting electrical contact between said metallized substrate and said first set of respective electrodes; and

generating a potential difference between said respective electrodes of said first set of a first magnitude to at least partially demetallize selected areas of said substrate at one of said electrodes;

selectively effecting electrical contact between said metallized substrate and the respective electrodes of a second set of respective electrodes;

generating a potential difference between said respective electrodes of said second set of a second magnitude to at least partially demetallize selected areas of said substrate at one of said electrodes.

37. An apparatus for demetallizing a metallized web moving along a path of the type comprising first and second electrodes, means for generating a potential difference between said electrodes, and means for establishing an electrical connection between the electrodes and the metallized web, improved wherein:

said second electrode includes a curved portion and is formed, at least in part, of aluminum and portions thereof are anodized, in accordance with a predetermined pattern, to render such portions non-conductive, whereby said metallized web is demetallized in accordance with said pattern; and

said means for establishing an electrical connection between said electrodes and said web includes means for forming a curved portion in said web path oppositely directed from the curved portion of said second electrode and biasing said web against said curved portion of said second electrode, in said curved portion of said web path.

38. An apparatus for demetallizing a metallized web moving along a path of the type comprising first and second electrodes, means for generating a potential difference between said electrodes, and means for establishing an electrical connection between the electrodes and the metallized web, improved wherein:

said second electrode includes a curved portion and portions manifesting a predetermined pattern are plated with a conductive material, whereby said metallized web is demetallized in accordance with said pattern; and

said means for establishing an electrical connection between said electrodes and said web includes means for forming a curved portion in said web path oppositely directed from the curved portion of said second electrode and biasing said web against said curved portion of said second electrode, in said curved portion of said web path.

39. The apparatus of claim 38 wherein portions of said second electrode in accordance with aid pattern are plated with nickel.

40. A method for making microwavable packaging material comprising a substrate having metallized areas of different optical density from a metallized substrate, said method comprising the steps of:

selectively effecting electrical contact between said metallized substrate and a first set of respective electrodes;

generating a potential difference between said respective electrodes of said set of a magnitude to at least partially demetallize selected areas of said substrate at one of said electrodes;

varying the optical density of predetermined areas of said substrate by selectively effecting electrical contact between said metallized substrate and the respective electrodes of a second set of respective electrodes to at least partially demetallize such predetermined ares of said substrate; and

,

varying the magnitude of the potential difference between the electrodes of said second set.

41. A method for making microwavable packaging material comprising a substrate having metallized areas of different optical density from a metallized substrate, said method comprising the steps of:

selectively effecting electrical contact between said metallized substrate and a first set of respective electrodes;

generating a potential difference between said respective electrodes of said first set of a magnitude to at least partially demetallize selected areas of said substrate at one of said electrodes, said one of said first set of electrodes manifesting a first part of a composite pattern;

varying the optical density of predetermined areas of said substrate by selectively effecting electrical contact between said metallized substrate and the respective electrodes of a second set of respective electrodes to at least partially demetallize such predetermined ares of said substrate, wherein one of said second set of electrodes manifests a second part of said composite pattern;

routing said substrate along a path to said first and second set of electrodes in sequence;

effecting demetallizaton of said metallized substrate in accordance with said first part of said pattern at said first mentioned set electrode; and

effecting demetallizaton of said metallized substrate in accordance with said second part of said pattern at said second set electrode.

42. The method of claim 41 wherein:

said first part of said pattern comprises a portion aligned with the direction of movement of said metallized substrate along said path; and

said second part of said pattern comprises a portion transverse to the direction of movement of said metallized substrate along said path.

43. A method for making microwavable packaging material comprising a substrate having metallized areas of different optical density from a metallized substrate, said method comprising the steps of:

selectively effecting electrical contact between said metallized substrate and a first set of respective electrodes;

generating a potential difference between said respective electrodes of said first set of a magnitude to at least partially demetallize selected areas of said substrate at one of said electrodes, said one of said first set of electrodes manifesting a first pattern;

varying the optical density of predetermined areas of said substrate by selectively effecting electrical contact between said metallized substrate and the respective electrodes of a second set of respective electrodes to at least partially demetallize such predetermined areas of said substrate, wherein one of said second set of electrodes manifests a second pattern including at least one element in common with said first pattern;

routing said substrate along a path to said first and said second set of electrodes in sequence; and

effecting further demetallization of said metallized substrate in accordance with said element common to said first and second patterns at said second set electrode to provide a composite pattern with elements of differing optical density.

44. An apparatus for making microwavable packaging material, comprising:

means for routing a metallized substrate along a path;

first and second electrodes disposed in spaced relation along said path, said second electrode including conductive portions and non-conductive portions corresponding to a first demetallization pattern;

means for selectively establishing a potential difference between said first and second electrodes; and

means for establishing an electrical contact between said metallized substrate and said first and second electrode to at least partially demetallize areas on said substrate, such that each of said substrate areas manifest a desired optical density;

third and fourth electrodes disposed along said path in spaced relation to said first and second electrodes, said fourth electrode bearing a second demetallization pattern;

means for selectively establishing a potential difference between said third and fourth electrodes; and

means for establishing an electrical contact between said substrate and said third and fourth electrodes to at least partially demetallize said substrate in accordance with said second demetallizaton pattern.

45. The apparatus of claim 44 wherein said first demetallization pattern includes a plurality of elements and said second demetallization pattern includes at least one element disposed in accordance with an element of said first demetallization pattern, such that partially demetallized areas of different optical densities are formed on said substrate.

46. A method for making microwavable packaging material comprising a substrate having metallized areas of different optical density from a metallized substrate, said method comprising the steps of:

selectively effecting electrical contact between said metallized substrate and a set of respective electrodes;

generating a potential difference between said respective electrodes of said set of a magnitude to at least partially demetallize selected areas of said substrate at one of said electrodes; and

varying the optical density of predetermined areas of said substrate by varying the magnitude of said potential difference to vary the extent of the partial demetallization of said predetermined areas of said substrate.

47. A method of selectively demetallizing a metallized web moving along a web path, comprising the steps of:

selectively generating a potential difference between first and second electrodes disposed spaced apart along said web path;

effecting respective electrical contacts between said moving web and said first electrode and between said web and said second electrode, producing a high density current to demetallize said web at said second electrical contact; and

varying said potential difference to selectively vary the percentage demetallization and create partially demetallized areas on said web.

48. A method of making packaging for microwavable food stuffs, said packaging material having predetermined regions of different optical density, said method comprising the steps of:

conveying a metallized web along a web path, into electrical contact with first and second electrodes disposed in spaced relation along said web path, said second electrode bearing a desired demetallization pattern;

selectively generating a potential difference between said second electrode and said web;

demetallizing said web in accordance with said desired demetallizaton pattern by effecting a current flow between said second electrode and said web;

said demetallizing step including the step of partially demetallizing portions of said web to form partially demetallized areas of different optical densities.

49. A method for making microwavable packaging material comprising a substrate having metallized ares of different optical density from a metallized substrate having a characteristic resistance of on the order of 100 ohm/square, said method comprising the steps of:

selectively effecting electrical contact between said metallized substrate and a set of respective electrodes;

generating a potential difference between said respective electrodes of said set of a magnitude to partially demetallize selected areas of said substrate at one of said electrodes.