Methods for changing the shape of a surface of a shape memory polymer article

• US 8,236,226 B2
• Filed: 04/22/2011
• Issued: 08/07/2012
• Est. Priority Date: 07/28/2006
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Sherman, Audrey A., Bryan, William J, Galkiewicz, Robert K., Mazurek, Mieczyslaw H., Starkey, James R., Winkler, Wendi J., Zhang, Haiyan, Olofson, Jeffrey M.
• Primary Examiner(s): Ewald, Maria Veronica
• Assistant Examiner(s): Grun, Robert J
• Application Number:
  US13/092,165
• Publication Number:
  US 20110198781A1
• Time in Patent Office: 473 Days
• Field of Search: 264/293, 264/294, 264/295, 264/296, 264/496, 264/650
• US Class Current: 264/293
• CPC Class Codes: B29C 2059/023 Microembossing
• CPC Class Codes: B29C 2791/001 Shaping in several steps
• CPC Class Codes: B29C 37/0053 Moulding articles characterised by the shape of the surface, e.g. ribs, high polish mould construction therefor B29C33/42; surface shaping of articles B29C59/00; by incorporating filler in or near the surface B29C70/64
• CPC Class Codes: B29C 43/26 in several steps B29C43/30 takes precedence not applied
• CPC Class Codes: B29C 59/02 by mechanical means, e.g. pressing B29C59/007 takes precedence; embossing expanded porous articles B29C44/5627
• CPC Class Codes: B29C 59/18 by liberation of internal stresses, e.g. plastic memory

Abstract

Methods for changing the shape of a surface of an article are disclosed. The methods may include providing a liquid polymer precursor, casting the precursor against a first tool assembly, curing the precursor to form a shape memory polymer substrate, deforming one or more surfaces of the substrate, and mobilizing the shape memory polymer to shift the deformed surface of the substrate from a deformed shape to a pre-set shape.

Claims

1. A method for changing the shape of a surface of an article, comprising the steps of:

providing a curable liquid polymer precursor;

casting the precursor against a first tool assembly having a first surface structure that is planar;

curing the precursor to form a shape memory polymer substrate having a pre-set shape corresponding to the first surface structure, the substrate including a shape memory polymer;

removing the substrate from the first tool assembly;

deforming a surface of the substrate with the pre-set shape against a second tool assembly having a second surface structure that includes a microstructure, to form a deformed surface on the substrate with a deformed shape corresponding to the second surface structure, wherein the deforming step includes applying heat and pressure to the substrate;

mobilizing the shape memory polymer to shift the deformed surface from the deformed shape to the pre-set shape; and

removing a portion of the substrate from the deformed surface.

2. The method of claim 1, wherein the deformed surface includes a plurality of wells.

3. The method of claim 2, further comprising the step of disposing a fluid in the wells.

4. The method of claim 3, wherein the fluid includes an adhesive.

5. The method of claim 3, further comprising the step of disposing a film over the wells.

6. The method of claim 1, wherein the step of mobilizing the shape memory polymer to shift the deformed surface from the deformed shape to the pre-set shape defines a negative surface in the substrate corresponding to the portion the substrate removed from the deformed surface.

7. The method of claim 1, wherein the deformed surface has a retroreflective cube corner structure.

8. The method of claim 7, wherein the step of mobilizing the shape memory polymer to shift the deformed surface from the deformed shape to the pre-set shape disrupts the retroreflective cube corner structure.

9. The method of claim 8, wherein the substrate comprises a portion of a license plate assembly, and further comprising the step of attaching the substrate to a mounting plate of the license plate assembly.

10. The method of claim 1, wherein the step of mobilizing the shape memory polymer to shift the deformed surface from the deformed shape to the pre-set shape includes mobilizing the shape memory polymer in substantially all of the substrate.

11. The method of claim 1, wherein the step of mobilizing the shape memory polymer to shift the deformed surface from the deformed shape to the pre-set shape includes mobilizing the shape memory polymer in only a portion of the substrate.

12. The method of claim 1, wherein the step of mobilizing the shape memory polymer to shift the deformed surface from the deformed shape to the pre-set shape includes heating the substrate.

13. The method of claim 1, wherein the step of mobilizing the shape memory polymer to shift the deformed surface from the deformed shape to the pre-set shape includes applying a solvent to the substrate.

14. The method of claim 1, wherein the substrate comprises a backing member, and further comprising the step of disposing the backing member on an adhesive assembly, the adhesive assembly including an adhesive substrate and a self-supporting adhesive disposed on the adhesive substrate.

15. The method of claim 1, further comprising the step of disposing a conductive layer on the deformed surface.

16. The method of claim 15, wherein the step of disposing a conductive layer on the deformed surface includes vapor coating or spray coating.

17. The method of claim 15, wherein the step of mobilizing the shape memory polymer to shift the deformed surface from the deformed shape to the pre-set shape disrupts the conductive layer.

18. The method of claim 1, wherein the shape memory polymer comprises a copolymer network comprising the reaction product of a free radically polymerizable siloxane having greater than one functional free radically polymerizable group and at least one (meth)acrylate monomer, wherein the at least one (meth)acrylate monomer, when homopolymerized, forms a homopolymer having a glass transition temperature, a melting temperature, or both greater than about 40°

C.