Uniaxially oriented article having a structured surface

• US 20060141220A1
• Filed: 12/23/2004
• Published: 06/29/2006
• Est. Priority Date: 12/23/2004
• Status: Abandoned Application

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Ouderkirk, Andrew J., Biernath, Rolf W., Brott, Robert L., Merrill, William Ward, Benson, Olester Jr., Kowitz, David A.
• Application Number:
  US11/184,027
• Publication Number:
  US 20060141220A1
• Time in Patent Office: Days
• US Class Current: 428/156
• CPC Class Codes: B29C 55/04 uniaxial, e.g. oblique
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: Y10T 428/24479 including variation in thickness

Abstract

A process for uniaxially stretching films having a structured surface comprising a geometric feature is described. The process provides a film in which the cross sectional shape of the feature after stretching is substantially identical to the cross sectional shape of the feature prior to stretching. Structured surface articles are also described. The articles have substantially the same uniaxial orientation throughout the film, including the geometric structure.

Claims

1. A uniaxially oriented structured surface article comprising:

(a) a polymeric body having (i) a first and a second surface, and (ii) first and second in-plane axes that are orthogonal with respect to each other and a third axis that is mutually orthogonal to the first and second in-plane axis in a thickness direction of the polymeric film; and

(b) a surface portion comprising a linear geometric feature disposed on the first surface of the polymeric body, the linear geometric feature being disposed on the body in a direction substantially parallel to the first in-plane axis of the polymeric film;

wherein the article has a stretch ratio of at least 1.5 in the direction of the first in-plane axis, and wherein the ratio of the larger to the smaller of the stretch ratios along the second in-plane axis and the third axis is 1.4 or less, and wherein the article has substantially the same uniaxial orientation throughout the thickness of the body and the height geometric feature.

2. The article of claim 1 wherein the geometric feature and the body each have a thickness and wherein the ratio of the thickness of the body to the height of the geometric feature is at least 2.

3. The article of claim 1 which is birefringent.

4. The article of claim 3 which is positively birefringent.

5. The article of claim 3 which is negatively birefringent.

6. The article of claim 3 which has a relative birefringence of 0.3 or less.

7. The film of claim 1 further comprising a plurality of linear geometric features of the first surface of the polymeric body.

8. The film of claim 7 wherein the plurality of geometric features are substantially aligned with the first in-plane axis.

9. The film of claim 8 further comprising a plurality of second geometric features disposed on the second surface of the body in a direction that is substantially parallel to the first in-plane axis.

10. The film of claim 1 wherein the uniaxially oriented polymeric film has (i) a first index of refraction (n₁) along the first in-plane axis, (ii) a second index of refraction (n₂) along the second in-plane axis, and (iii) a third index of refraction (n₃) along the third axis, wherein n₁≠

n₂ and n₁≠

n₃ and n₂ and n₃ are substantially equal to one other relative to their differences with n₁.