Article featuring a predetermined pattern of randomly distributed microspheres and methods of making the same

Patent metadata

Field	Value
Publication number	US-11413846-B2
Application number	US-201716089418-A
Country	US
Kind code	B2
Filing date	Mar 29, 2017
Priority date	Mar 30, 2016
Publication date	Aug 16, 2022
Grant date	Aug 16, 2022

Abstract

Described herein is an article having a microsphere layer comprising a monolayer of microspheres, the monolayer of microspheres comprising a first area substantially free of microspheres and a second area comprising a plurality of randomly-distributed microspheres, wherein the monolayer of microspheres comprises a predetermined pattern, the predetermined pattern comprises at least one of (i) a plurality of the first areas, (ii) a plurality of the second areas, and (iii) combinations thereof; and (b) a bead bonding layer disposed on the microsphere layer, wherein the plurality of microspheres are partially embedded in a first major surface of the bead bonding layer, wherein the article has a retroreflectivity (Ra) of less than 5.0 candelas/lux/square meter. Also disclosed herein are transfer carriers and methods of making the articles and transfer carriers.

First claim

What is claimed is:

1. An article comprising:
(a) a microsphere layer comprising a monolayer of microspheres, wherein the monolayer of microspheres comprises a predetermined pattern, the predetermined pattern comprises at least one first area substantially free of microspheres and at least one second area comprising a plurality of randomly positioned microspheres wherein at least one of:
(i) the at least one first area comprises a third area and a fourth area substantially free of microspheres;
(ii) the at least one second area comprises a fifth area and a sixth area comprising a plurality of randomly positioned microspheres; or
(iii) both (i) and (ii); and

(b) a bead bonding layer disposed on the microsphere layer, wherein the plurality of microspheres are partially embedded in a first major surface of the bead bonding layer,
wherein the article has a retroreflectivity (R a ) of less than 5.0 candelas/lux/square meter when measured following ASTM E810-03 (2013) with a 0.2 degree observation angle and a 5 degree entrance angle.

2. The article of claim 1 , wherein the bead bonding layer comprises at least one of (i) a resin comprising a fluorine-containing polymer, (ii) a linear resin, (iii) a resin having low crosslink densities, (iv) a resin having high crosslink densities, and (v) combinations and blends thereof.

3. The article of claim 2 , wherein the resin having low cross link densities are those resins comprising lightly crosslinked material having a molecular weight per crosslink point of greater than about 2,800 g/mol.

4. The article of claim 2 , wherein the fluorine-containing polymer is selected from at least one of the following: fluoroolefins, fluorourethanes, and combinations thereof.

5. The article of claim 1 , wherein the density of microspheres in the at least one first area is less than 20% of the density of microspheres in the at least one second area.

6. The article of claim 1 , wherein a refractive index of the microspheres is less than 1.6.

7. The article of claim 1 , wherein the microspheres covers more than 20% and less than 60% of the surface of the bead bonding layer.

8. The article of claim 1 , wherein the microspheres have an average diameter of 20 to 200 micrometers.

9. The article of claim 1 , wherein the article further comprises a reinforcing layer formed on a second major surface of the bead bonding layer opposite the microsphere layer wherein the reinforcing layer is selected from one of the following: polyurethane resins, acrylic resins, polyester resins, epoxy resins, and mixtures thereof.

10. The article of claim 1 , wherein the microspheres within the at least one second area are closely packed.

11. The article of claim 1 , wherein the at least one second area comprises at least three microspheres.

12. The article of claim 1 , wherein the article has a pencil hardness of at least 9H at 7.5 Newtons and wherein the microspheres covers more than 20% and less than 60% of the surface of the bead bonding layer.

13. The article of claim 1 , wherein the article is transparent.

14. The article of claim 1 , wherein the article is thermoformable.

15. A thermoset article derived from the thermoformable article of claim 14 .

16. The thermoset article of claim 15 , wherein the thermoset article is a 3-dimensional shaped article.

17. The article of claim 1 , wherein the at least one first area is continuous across the article and at least one second area is discontinuous.

18. The article of claim 1 , wherein the at least one second area is continuous across the article and the at least one first area is discontinuous.

Assignees

• 3M Innovative Properties Co

Inventors

• Walker Jr Christopher B
• Alabi Toheeb B
• Chen-Ho Kui
• Clark John C
• Gundale Jeremy P
• Krishnan Vivek
• Kugel Alexander J
• Pekurovsky Mikhail L
• Pommer Chris A
• Stay Matthew S

Classifications

• C09D5/006 Primary

  Anti-reflective coatings · CPC title

• B32B27/36

  comprising polyesters · CPC title

• G02B5/128

  transparent spheres being embedded in matrix · CPC title

• B32B7/06

  permitting easy separation · CPC title

• B32B7/027

  Thermal properties · CPC title