ANGULAR BRIGHTNESS MICROPRISMATIC RETROREFLECTIVE FILM OR SHEETING INCORPORATING A SYNDIOTACTIC VINYL AROMATIC POLYMER

• US 20010008679A1
• Filed: 01/29/1999
• Published: 07/19/2001
• Est. Priority Date: 01/29/1999
• Status: Active Grant

• Current Assignee: 3M Company, 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: SMITH, KENNETH L., OJEDA, JAIME R., TABAR, RONALD J.
• Granted Patent: US 6,274,221 B2
• Time in Patent Office: Days
• US Class Current: 428/141
• CPC Class Codes: G02B 5/124 plural reflecting elements forming part of a unitary plate or sheet
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/24479 including variation in thickness

Abstract

A novel microprismatic retroreflective film or sheeting is provided which comprises a transparent semicrystalline polymer. The microprismatic retroreflective film or sheeting of the present invention offers superior retroreflective brightness at large angles of incidence and at large observational angles. Syndiotactic vinyl aromatic polymers, especially syndiotactic polystyrene and copolymers thereof, are preferred semicrystalline polymers, as they impart good dimensional stability and resistance to moisture, and can be made resistant to UV radiation. Signing materials comprising these microprismatic retroreflective films provide improved performance for off-angle illumination and viewing in traffic control and other signing applications.

Claims

1. A retroreflective film, comprising a polymer derived from a syndiotactic vinyl aromatic monomer.

2. The film of

claim 1

, wherein said syndiotactic vinyl aromatic polymer is a transparent semicrystalline polymer.

3. The film of

claim 1

, wherein said syndiotactic vinyl aromatic polymer comprises at least 80% by weight of styrene moieties.

4. The film of

claim 3

, wherein said syndiotactic vinyl aromatic polymer further comprises at least 5% by weight of para-methylstyrene moieties.

5. The film of

claim 1

, wherein said syndiotactic vinyl aromatic polymer is syndiotactic polystyrene.

6. The film of

claim 1

, wherein said film has at least one microprismatic surface.

7. The film of

claim 1

, wherein said film has a retroreflective surface having cube-cornered geometry.

8. The film of

claim 1

, wherein said syndiotactic vinyl aromatic polymer has at least 20% by weight of syndiotactic chain segments.

9. The film of

claim 1

, wherein said syndiotactic vinyl aromatic polymer has between 30% and 98% by weight of syndiotactic chain segments.

10. The film of

claim 1

, wherein said syndiotactic vinyl aromatic polymer has between 85% and 95% by weight of syndiotactic chain segments.

11. The film of

claim 1

, further comprising between about 0 5 and 2.0 parts by weight of a UV absorbing material per 100 parts by weight of said syndiotactic vinyl aromatic polymer.

12. The film of

claim 1

, further comprising an antioxidant.

13. The film of

claim 12

, wherein said antioxidant is present in an amount of between about 1×

10<sup>−

4</sup> and about 2 parts by weight per 100 parts by weight of said syndiotactic vinyl aromatic polymer.

14. The film of

claim 12

, wherein said antioxidant is present in an amount of between about 0.001 and about 1 parts by weight per 100 parts by weight of said syndiotactic vinyl aromatic polymer.

15. The film of

claim 12

, wherein said antioxidant is present in an amount of between about 0.01 and about 0.5 parts by weight per 100 parts by weight of said syndiotactic vinyl aromatic polymer.

16. The film of

claim 12

, wherein said antioxidant is a hindered phenolic resin.

17. A sign, comprising the film of

claim 1

.