Multilayer polyester film with a low coefficient of friction

• US 5,783,283 A
• Filed: 03/08/1996
• Issued: 07/21/1998
• Est. Priority Date: 03/08/1996
• Status: Expired due to Term

• Current Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Original Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Inventors: Klein, James A., Lucking, Raymond L., Carter, Brandt K., Israel, Sheldon J.
• Primary Examiner(s): Chen, Vivian
• Application Number:
  US08/612,526
• Time in Patent Office: 865 Days
• Field of Search: 428/910, 428/141, 428/480, 428/694 TR, 428/694 BR, 428/694 SG
• US Class Current: 428/141
• CPC Class Codes: B32B 2367/00 Polyesters, e.g. PET, i.e. polyethylene terephthalate
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: C08J 2367/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds; C08J2367/06 takes precedence
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: G11B 5/73927 Polyester substrates, e.g. polyethylene terephthalate
• CPC Class Codes: G11B 5/73929 comprising naphthalene ring compounds, e.g. polyethylene naphthalate substrates
• CPC Class Codes: G11B 5/73931 Two or more layers, at least one layer being polyester
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]

Abstract

A multilayer film is provided with a slippery surface layer by crystallization in an underlying layer which results in the deformation of an overlying surface layer without the use of particulate slip agents. The films may be formed by alternating layers of a naphthalene dicarboxylic acid polyester and a terephthalic acid polyester.

Claims

1. A multilayer film, comprising:

a surface layer comprising a first polymer; and

a second layer, adjacent to said surface layer, comprising a second polymer;

wherein said surface layer and said second layer are devoid of particulate slip agents, wherein said second polymer is crystallized into a plurality of crystalline structures, and wherein said surface layer is sufficiently deformed by said crystalline structures such that said surface layer has a surface roughness R_A of at least about 10 nm as measured by the Rodenstock technique.

2. The film of claim 1, wherein the surface layer has a surface roughness R_A of at least about 20 nm as measured by the Rodenstock technique.

3. The film of claim 1, wherein the surface layer has a surface roughness R_Q of at least about 30 nm as measured by the Rodenstock technique.

4. The film of claim 1, wherein the surface layer has a surface roughness R_A of at least about 7 nm as measured by the interferometry technique.

5. The film of claim 1, wherein the surface layer has a surface roughness R_Q of at least about 9 nm as measured by the interferometry technique.

6. The film of claim 1, wherein said film has a percent haze of less than about 8%.

7. The film of claim 1, wherein said film has a static coefficient of friction of less than about 3.2.

8. The film of claim 1, wherein said film has a static coefficient of friction of less than about 1.0.

9. The film of claim 1, wherein said film has a kinetic coefficient of friction of less than about 1.0.

10. The film of claim 1, wherein said film has a kinetic coefficient of friction of less than about 0.6.

11. The multilayer film of claim 1, wherein said first polymer comprises a naphthalene dicarboxylic acid polyester and said second polymer comprises a terephthalic acid polyester.

12. The film of claim 11, wherein said second polymer is polyethylene terephthalate.

13. The film of claim 12, wherein said surface layer comprises polyethylene naphthalate.

14. The multilayer film of claim 11, wherein said naphthalene dicarboxylic acid polyester is polyethylene naphthalate and said terephthalic acid polyester is polyethylene terephthalate.

15. The multilayer film of claim 1, wherein said multilayer film comprises at least 7 alternating layers of a first layer comprising a naphthalene dicarboxylic acid polyester and a second layer comprising a terephthalic acid polyester.

16. The multilayer film of claim 1, wherein said multilayer film comprises at least 13 alternating layers of a first layer comprising a naphthalene dicarboxylic acid polyester and a second layer comprising a terephthalic acid polyester.

17. A film having a slippery surface, comprising:

a surface layer which is devoid of particle slip agents; and

a second layer disposed beneath said surface layer;

wherein said second layer consists essentially of a polymeric material which is crystallized into spherulitic structures of sufficient size and quantity to deform said surface layer.

18. The film of claim 17, wherein said surface layer and said second layer are adjacent.

19. The film of claim 17, wherein said surface layer comprises polyethylene naphthalate, and said second layer comprises polyethylene terephthalate.

20. The film of claim 17, wherein at least one surface of said film is devoid of slip agents, and wherein at least one surface of said film has a surface roughness R_Q of at least about 20 nm as measured by the Rodenstock technique.

21. A film comprising a multilayer film comprising at least about 7 alternating layers of a first polymer and a second polymer in combination with a surface layer, wherein the surface layer comprises:

a first layer comprising said first polymer; and

a second layer comprising said second polymer;

wherein said first polymer is a terephthalic acid polyester and said second polymer is a naphthalene dicarboxylic acid polyester, wherein said first layer is disposed between said second layer and said multilayer film, said second layer being devoid of particulate slip agents, and wherein said first layer is sufficiently crystallized so as to deform said second layer such that the surface layer has a root mean square average surface roughness R_q of at least about 100 nm.

22. The film of claim 21, wherein the terephthalic acid polyester in said first layer contains spherulitic structures.

23. The film of claim 21, wherein said multilayer film has at least 13 alternating layers of said first and second polymers.

24. A multilayer polyester film, comprising:

a surface layer; and

a second layer adjacent to said surface layer, said second layer comprising a polyester and containing a plurality of crystalline structures;

wherein said surface layer and said second layer are devoid of particulate slip agents, and wherein said surface layer is sufficiently deformed by said crystalline structures in said second layer such that said surface layer has a surface roughness R_A of at least about 10 nm as measured by the Rodenstock technique.

25. The multilayer film of claim 24, wherein said surface layer has a surface roughness R_A of at least about 20 nm as measured by the Rodenstock technique.

26. A multilayer polyester film, comprising:

alternating layers of a first polymer derived from naphthalene dicarboxylic acid and a second polymer derived from terephthalic acid;

wherein a first layer forming a first surface of the film comprises said first polymer and is substantially devoid of particulate slip agents, wherein a second layer adjacent to said first layer comprises said second polymer, and wherein said second polymer in said second layer is crystallized into crystalline structures of sufficient size and quantity to substantially disrupt the surface smoothness of said first layer.

27. The film of claim 26, wherein said first surface has a surface roughness R_A of at least about 10 nm as measured by the Rodenstock technique.

28. The film of claim 26, wherein said film has at least 7 alternating layers of said first polymer and said second polymer.

29. The film of claim 26, wherein said film has at least 13 alternating layers of said first polymer and said second polymer.

30. A film comprising a multilayer film comprising at least about 5 alternating layers of a first polymer and a second polymer in combination with a surface layer, wherein the surface layer comprises:

a first layer comprising a naphthalene dicarboxylic acid polyester; and

a second layer comprising a terephthalic acid polyester;

wherein said surface layer is devoid of particulate slip agents, wherein said second layer is disposed between said first layer and said multilayer film, wherein said second layer is sufficiently crystallized so as to deform said first layer such that said surface layer has a surface roughness R_A of at least about 10 nm as measured by the Rodenstock technique, wherein said first polymer comprises a naphthalene dicarboxylic acid polyester, and wherein said second polymer comprises a terephthalic acid polyester.

31. A multilayer film, comprising:

a surface layer comprising a first polymer; and

a second layer, disposed beneath said surface layer, comprising a second polymer;

wherein said surface layer is devoid of particulate slip agents, wherein said second polymer is crystallized into a plurality of crystalline structures of sufficient size and quantity to deform said surface layer, and wherein said surface layer has a root mean square average surface roughness R_q of at least about 100 nm.

32. The multilayer film of claim 31, wherein said second polymer is a polyester.

33. The multilayer film of claim 31, wherein said second polymer is polyethylene terephthalate.