Method for producing high gloss cup

• US 5,039,560 A
• Filed: 05/26/1989
• Issued: 08/13/1991
• Est. Priority Date: 05/26/1989
• Status: Expired due to Fees

• Current Assignee: Sweethart Cup Company Incorporated
• Original Assignee: Sweetheart Cup Company, Inc. (Robert Charles Dart)
• Inventors: Hammett, Daniel E., Matheson, Derek S., Kemmet, Carlton L., Durgin, Ronald A., Border, Delvin K.
• Primary Examiner(s): BELL, JANYCE A
• Application Number:
  US07/358,007
• Time in Patent Office: 809 Days
• Field of Search: 427/240, 427/326, 427/384, 427/395, 427/398.3, 427/398.2, 427/374.1, 427/374.5, 427/374.2, 427/422, 427/425
• US Class Current: 427/240
• CPC Class Codes: B05D 1/002 the substrate being rotated
• CPC Class Codes: B05D 2203/22 Paper or cardboard
• CPC Class Codes: B05D 2501/10 Wax
• CPC Class Codes: B05D 3/00 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 successively applying liquids or other fluent materials B05D1/36; drying ovens F26B
• CPC Class Codes: B05D 3/12 by mechanical means

Abstract

A method is described for continuously producing a smooth, high gloss coating on a paper container comprising the steps of applying a substantially uniform coating of melted wax material to the outside surface of the container or sheet stock, maintaining the temperature of the wax coating above its melting point and above its congealing temperature, imparting a constant surface velocity to the outside surface of the container or sheet stock and applying a substantially uniform film of liquid coolant, particularly water, to the outside surface of the container or sheet stock whereby the surface velocity of the coolant is substantially equal to the surface velocity of the container or sheet stock.

Claims

1. A method of continuously producing a smooth, high gloss coating on a paper container comprising the steps of:

(a) applying a substantially uniform coating of melted wax material to at least the outside surface of said container;

(b) maintaining the temperature of said wax coating at a temperature above its melting point;

(c) imparting a constant angular velocity to said container to thereby define an outside surface velocity of said container; and

(d) applying a substantially uniform thin film of liquid coolant to said outside surface of said container, said coolant having a linear velocity substantially equal to said outside surface velocity of said container and being applied substantially tangential to said outside surface.

2. A method according to claim 1, wherein said temperature of said wax coating is approximately 160°

F.

3. A method according to claim 1, wherein said paper container is subjected to a constant spin rate in the range of about 250-400 rpm to thereby define said constant angular velocity.

4. A method according to claim 1, wherein the temperature of said liquid coolant is about 45°

F.

5. A method according to claim 1, wherein said wax coating has an average melting temperature in the range of about 130°

F. to 140°

F.

6. A method according to claim 1, wherein said temperature of said liquid coolant is in the range of about 40°

F. to 55°

F.

7. A method for continuously producing a smooth, high gloss coating on a paper container, said paper container having a coating of hardened wax previously applied to substantially the entire outside surface thereof, comprising the steps of:

(a) heating said paper container and said wax coating to a temperature above the congealing temperature of said wax for a time sufficient to cause said wax to form a uniform liquid film on said outside surface;

(b) imparting a constant angular velocity to said container to thereby define an outside surface velocity of said container;

(c) maintaining the temperature of said wax coating at a temperature above its melting point; and

(d) applying a substantially uniform thin film of liquid coolant to said outside surface of said container, said coolant having a linear velocity substantially equal to said outside surface velocity of said container and being applied substantially tangential to said outside surface.

8. A method according to claim 7, wherein said temperature of said wax coating is approximately 160°

F.

9. A method according to claim 7, wherein said paper container is subjected to a constant spin rate in the range of about 250-400 rpm to thereby define said constant angular velocity.

10. A method according to claim 7, wherein the temperature of said liquid coolant is about 45°

F.

11. A method according to claim 7, wherein steps (a) through (d) are carried out such that said wax coating has an average melting temperature in the range of about 130°

F. to 140°

F.

12. A method according to claim 7, wherein said temperature of said liquid coolant is in the range of about 40°

F. to 55°

F.

13. A method for continuously producing a uniform, smooth, high gloss coating on a flat paper web comprising the steps of:

(a) advancing said flat paper web along a horizontal path while applying a substantially uniform coating of melted wax material to the top surface thereof;

(b) maintaining the temperature of said melted wax above the congealing point of said wax material for a time sufficient to cause said wax material to form a uniform liquid film across the top surface of said flat paper web;

(c) imparting a constant linear velocity to said coated surface of said flat paper web; and

(d) applying a substantially uniform thin film of liquid coolant to said coated surface of said flat paper web, said coolant having a linear velocity substantially equal to said linear velocity of said flat paper web and being applied substantially tangential to said coated surface.

14. A method according to claim 13, wherein step (d) further comprises the steps of causing said flat paper web to pass over a rotating drum thereby causing said flat web to take on a curvilinear configuration while passing over said drum and imparting a constant surface velocity to said flat paper web and wherein said substantially uniform thin film of liquid coolant is applied to said coated surface of said flat paper web at the point of movement over said drum and at a linear velocity substantially equal to said surface velocity of said flat paper web and being applied substantially tangential to said coated surface.

15. A method according to claim 13, wherein said temperature of said wax coating is approximately 160°

F.

16. A method according to claim 13, wherein the temperature of said liquid coolant is about 45°

F.

17. A method according to claim 13, wherein said wax coating has an average melting temperature in the range of about 130°

F. to 140°

F.

18. A method according to claim 13, wherein said temperature of said liquid coolant is in the range of about 40°

F. to 55°

F.

19. A method for continuously producing a uniform, smooth, high gloss coating on a flat paper web, said flat paper web having a coating of hardened wax previously applied to substantially the entire top surface thereof, comprising the steps of:

(a) heating said paper web and said wax coating to a temperature above the congealing temperature of said wax for a time sufficient to cause said wax to form a uniform liquid film on said top surface;

(b) imparting a constant linear velocity to said top surface of said paper web;

(c) maintaining the temperature of said melted wax above the congealing point of said wax; and

(d) applying a substantially uniform thin film of liquid coolant to said coated surface of said flat paper web, said coolant having a linear velocity substantially equal to said linear velocity of said flat paper web and being applied substantially tangential to said coated surface.

20. A method for continuously producing a smooth, high gloss coating on a paper container comprising the steps of:

(a) applying a substantially uniform coating of melted wax material to at least the outside surface of said container;

(b) maintaining the temperature of said wax coating at a temperature above its melting point;

(c) rotating said container at a constant angular velocity; and

(d) bringing a substantially uniform thin film of liquid coolant into substantially tangential contact with said outside surface of said rotating container at a velocity such that after said contact, said liquid film follows said outside surface of said rotating container at substantially said angular velocity.

21. A method according to claim 20, wherein said temperature of said wax coating is approximately 160°

F.

22. A method according to claim 20, wherein said paper container is subjected to a constant spin rate in the range of about 250-400 rpm to thereby define said constant angular velocity.

23. A method according to claim 20, wherein the temperature of said liquid coolant is about 45°

F.

24. A method according to claim 20, wherein said wax coating has an average melting temperature in the range of about 130°

F. to 140°

F.

25. A method for continuously producing a smooth, high gloss coating of wax on a paper cup of the type having a generally cylindrical configuration, said method comprising the steps of:

(a) applying a substantially uniform coating of melted wax material to the outside surface of said paper cup;

(b) maintaining the temperature of said wax coating at a temperature above its melting point;

(c) rotating said cup at a uniform spin rate to thereby define an outside surface velocity of said cup;

(d) applying a substantially uniform film of water at a temperature below said melting point of said wax coating, said film of water being applied tangential to the rotating cup surface under laminar flow conditions and having a velocity which is substantially equal to said outside surface velocity.