Method of making a polymeric film having structured surfaces via replication

• US 20060138694A1
• 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., Huizinga, John S., Merrill, William Ward, Benson, Olester Jr., Black, William B., Hennen, Daniel W.
• Application Number:
  US11/184,023
• Publication Number:
  US 20060138694A1
• Time in Patent Office: Days
• US Class Current: 264/210.200
• CPC Class Codes: B29C 39/148 characterised by the shape of the surface
• CPC Class Codes: B29C 43/222 characterised by the shape of the surface
• CPC Class Codes: B29C 55/04 uniaxial, e.g. oblique

Abstract

Method of Making a Polymeric Film Having Structured Surfaces Via Replication A method of making a polymeric film via a replication process is disclosed. The process provides a tool that has a negative version of a desired structured surface; contacting the negative surface of the tool to a polymeric material to form the desired surface in the polymeric material; removing the polymeric material having the desired structured surface from the tool; and uniaxially stretching the polymeric material.

Claims

1. A method of making a polymeric film having a desired structured surface comprising the steps of:

(a) providing a tool that comprises a negative surface of the desired structured surface;

(b) contacting the negative surface of the tool with a resin to create the desired structured surface, the desired structured surface comprising a geometric feature;

(c) optionally solidifying the resin to form a film having (i) the desired structured surface and an opposed 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 film;

(d) removing the film from the negative surface of the tool; and

subsequently

(e) stretching the polymeric film in a direction substantially parallel to the first in-plane axis of the polymeric film.

2. A method according to claim 1 wherein the cross sectional shape of the geometric feature before step (b) is substantially retained after step (b).

3. A method according to claim 1 wherein the molten resin is supplied to a gap between the tool and a second surface.

4. A method according to claim 1 wherein the negative surface of the tool comprises a layer of a release agent.

5. A method according to claim 1 wherein the release agent comprises a monolayer.

6. A method according to claim 1 wherein the release agent comprises a fluorochemical benzotriazole.

7. A method according to claim 1 wherein the polymeric film has a first orientation state prior to stretching and a second orientation state, different than the first orientation state, after orientation.

8. A method of making a desired microstructure surface film, the microstructure surface comprising a plurality of elongate geometric micro-features, the method comprising the steps of:

(a) providing a tool comprising a negative version of the desired microstructure surface;

(b) providing a polymeric resin to a gap formed between the master tool and a second surface;

(c) forming a polymeric film having the desired microstructure surface in the gap, the film having (i) first and second in-plane axes that are mutually orthogonal with respect to each other and a third axes that is mutually orthogonal with respect to the first and second in-plane axes in a thickness direction of the film, and (ii) the desired microstructure surface having the elongate micro-features positioned in a direction substantially parallel to the first in-plane axis;

(d) removing the polymeric film of step (c) from the tool; and

(e) stretching the polymeric film in a direction substantially parallel to the first in-plane axis.

9. A method according to claim 8 wherein the cross sectional shape of the elongate geometric features is substantially retained throughout stretching.

10. A method according to claim 9, wherein the oriented film comprises at least one layer with a first index of refraction (n₁) along the first in-plane axis, a second index of refraction (n₂) along the second in-plane axis, and 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 another relative to their differences with n₁.