Embossed oriented film

• US 5,108,814 A
• Filed: 04/13/1990
• Issued: 04/28/1992
• Est. Priority Date: 09/14/1987
• Status: Expired due to Term

• Current Assignee: Tredegar Film Products Corporation (Tredegar Corporation)
• Original Assignee: Tredegar Industries, Inc. (Tredegar Corporation)
• Inventors: Smith, Donald L., Harp, Raymond S.
• Primary Examiner(s): Robinson, Ellis P.
• Assistant Examiner(s): Loney, Donald J.
• Application Number:
  US07/509,332
• Time in Patent Office: 746 Days
• Field of Search: 426/156, 426/167, 426/166, 426/172, 426/174, 426/182, 426/409, 426/212, 426/216, 426/332, 426/220, 426/500, 426/516, 426/523, 156/209, 428/910, 428/220, 264/214, 264/284, 264/293
• US Class Current: 428/156
• CPC Class Codes: B29C 2037/92 Lubricating
• CPC Class Codes: B29C 55/18 by squeezing between surfaces, e.g. rollers
• CPC Class Codes: B29C 59/002 Component parts, details or accessories; Auxiliary operations
• CPC Class Codes: B29C 59/04 using rollers or endless belts
• CPC Class Codes: Y10S 428/91 Product with molecular orientation
• CPC Class Codes: Y10T 428/24479 including variation in thickness
• CPC Class Codes: Y10T 428/2457 Parallel ribs and/or grooves
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/24975 No layer or component greater than 5 mils thick
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/31 Surface property or characteristic of web, sheet or block
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31913 Monoolefin polymer
• CPC Class Codes: Y10T 428/31938 Polymer of monoethylenically unsaturated hydrocarbon

Abstract

Oriented or strength-enhanced embossed film is produced by introducing a thermoplastic film having an inert liquid lubricant covering its surfaces into the nip between at least one pair of rotating compression rolls under sufficient pressure to reduce the thickness of the film, and simultaneously embossing at least one of the film surfaces within the nip. While various inert liquids may be used as the lubricant, use of water for this purpose is preferred. The lubricant is believed to provide a hydrodynamic wedge at the film-compression roll interfaces, and for best results it is preferred to spray the lubricant (most preferably, water) into both incoming sides of the nip of the compression rolls.

Claims

1. A thermoplastic film which is simultaneously oriented and embossed to have a matte surface on one side and a smooth glossy surface on the other side and a nominal thickness of two mils or less, said film being oriented in an unbalanced manner wherein the elongation of said film in the machine direction is restricted relative to the elongation of said film in the transverse direction to produce a machine direction tensile strength of at least 20,000 psi and a transverse direction tensile strength of at least 4000 psi, said matte surface being in the range of 10 to 300 Ra surface roughness and said smooth, glossy surface being essentially free of surface flaws as observed at 700 magnification using a scanning electron microscope.

2. A film according to claim 1 wherein said thermoplastic film is a polyethylene film.

3. A film according to claim 1 wherein said matte surface is in the range of 10 to 150 Ra surface roughness.

4. A film according to claim 1 wherein said matte surface has a nominal surface roughness of approximately 50 Ra.

5. A film according to claim 4 wherein said thermoplastic film is a polyethylene film.