Surface-structured coatings

Patent metadata

Field	Value
Publication number	US-9976039-B1
Application number	US-201414505785-A
Country	US
Kind code	B1
Filing date	Oct 3, 2014
Priority date	Oct 4, 2013
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

We describe a new approach to fabricate polymeric materials with surface structures for applications as anti-reflective, anti-icing, superhydrophobic, superhydrophilic, de-wetting, and self-cleaning coatings. In some variations, a surface-textured layer comprises first microdomains and second microdomains each containing polymerized cross-linkable photomonomer, where the first microdomains have a higher average cross-link density than that of the second microdomains. The first microdomains and the second microdomains are in a peak-valley surface topology, providing surface texture with no filler particles. In some variations, a method to fabricate a surface-textured layer comprises: applying a cross-linkable photomonomer layer to a reflective substrate; exposing the photomonomer layer to a collimated light beam with no spatial variation, to initiate polymerization in first microdomains; and polymerizing other regions of the photomonomer layer to form second microdomains that are spatially separated from the first microdomains. The first microdomains have a higher average cross-link density compared to the second microdomains.

First claim

What is claimed is:

1. A surface-textured layer comprising first microdomains and second microdomains, wherein said surface-textured layer is characterized in that:
said first and said second microdomains contain polymerized cross-linkable photomonomer;
said first microdomains have a higher average cross-link density than that of said second microdomains;
said first microdomains and said second microdomains are disposed in an irregular peak-valley surface topology, wherein second microdomains are spatially separated from said first microdomains;
said surface-textured layer has a non-uniform or semi-uniform surface texture pattern, wherein said surface texture pattern within any selected 1 mm 2 area is unique and distinct from any other 1 mm 2 area; and
said surface-textured layer contains essentially no filler particles.

2. The surface-textured layer of claim 1 , wherein said first microdomains have an average length scale from about 0.1 μm to about 100 μm.

3. The surface-textured layer of claim 2 , wherein said first microdomains have an average length scale from about 1 μm to about 10 μm.

4. The surface-textured layer of claim 1 , wherein said second microdomains have an average length scale from about 0.1 μm to about 100 μm.

5. The surface-textured layer of claim 4 , wherein said second microdomains have an average length scale from about 1 μm to about 10 μm.

6. The surface-textured layer of claim 1 , wherein said peak-valley surface topology includes said first microdomains having a first-microdomain average peak height of about 0.01 μm to about 50 μm relative to a second-microdomain average valley depth.

7. The surface-textured layer of claim 6 , wherein said first-microdomain average peak height is about 0.5 μm to about 5 μm relative to said second-microdomain average valley depth.

8. The surface-textured layer of claim 1 , wherein said first microdomains are substantially in the form of approximately round two-dimensional regions in the normal orientation to said surface-textured layer, and wherein each of said first microdomains does not have uniform three-dimensional cross-sectional shape in the axial dimension.

9. The surface-textured layer of claim 1 , wherein said first microdomains are substantially in the form of lines.

10. The surface-textured layer of claim 1 , wherein said polymerized cross-linkable photomonomer is selected from the group consisting of polyurethanes, epoxies, acrylics, phenolic resins, urea-formaldehyde resins, phenol-formaldehyde resins, urethanes, siloxanes, and combinations thereof.

11. The surface-textured layer of claim 1 , wherein said polymerized cross-linkable photomonomer is derived from one or more ethylenically unsaturated precursors selected from the group consisting of ethylene, substituted olefins, halogenated olefins, 1,3-dienes, styrene, α-methyl styrene, vinyl esters, acrylates, methacrylates, acrylonitriles, acrylamides, N-vinyl carbazole, N-vinyl pyrolidone, and oligomers or combinations thereof.

12. The surface-textured layer of claim 1 , wherein said surface-textured layer is a transparent, anti-glaring layer.

13. The surface-textured layer of claim 1 , wherein said surface-textured layer further comprises hydrophilic molecules attached to functional groups, and wherein said surface-textured layer is a superhydrophilic layer.

14. The surface-textured layer of claim 1 , wherein said surface-textured layer further comprises hydrophobic molecules attached to functional groups, and wherein said surface-textured layer is a superhydrophobic layer.

15. The surface-textured layer of claim 1 , wherein said surface-textured layer further comprises hydrophobic colloidal particles, and wherein said surface-textured layer is an anti-icing layer.

16. The surface-textured layer of claim 1 , wherein said surface-textured layer is a coating or is part of a coating.

17. The surface-textured layer of claim 1 , wherein said surface-textured layer is an outer layer of a structural object or a freestanding object.

18. A surface-textured layer produced by a method comprising:
(a) applying a cross-linkable photomonomer layer to a reflective substrate;
(b) exposing said photomonomer layer to an exposure beam of photons, to initiate polymerization in a plurality of first microdomains, wherein said exposure beam is a substantially collimated beam with no spatial variation;
(c) continuing to apply said exposure beam to increase cross-link density associated with first microdomains, and to cause at least some polymerization in a plurality of second microdomains that are also within said photomonomer layer but spatially separated from said first microdomains; and
(d) recovering a surface-textured layer comprising said first microdomains and said second microdomains, wherein said first microdomains have a higher average cross-link density than that of said second microdomains,
wherein said surface-textured layer is further characterized in that:
said first microdomains and said second microdomains are disposed in an irregular peak-valley surface topology, wherein second microdomains are spatially separated from said first microdomains; and
said surface-textured layer has a non-uniform or semi-uniform surface texture pattern, wherein said surface texture pattern within any selected 1 mm 2 area is unique and distinct from any other 1 mm 2 area.

Assignees

• Hrl Lab Llc

Inventors

• Risbud Bartl Michael H
• Jacobsen Alan J

Classifications

• C09D133/04

  Homopolymers or copolymers of esters {(C09D143/04 takes precedence)} · CPC title

• C09D133/20

  Homopolymers or copolymers of acrylonitrile (C09D155/02 takes precedence) · CPC title

• C09D123/06

  Polyethylene · CPC title

• C09D5/006 Primary

  Anti-reflective coatings · CPC title

• C09D125/06

  Polystyrene · CPC title