High reflectance polycarbonate

Patent metadata

Field	Value
Publication number	US-9315675-B2
Application number	US-201514734565-A
Country	US
Kind code	B2
Filing date	Jun 9, 2015
Priority date	Apr 5, 2012
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

In an embodiment, a polycarbonate composition comprises: polycarbonate; 7 wt % to 20 wt % titanium dioxide, based upon a total weight of the polycarbonate composition; an optional flame retardant; and an optional UV stabilizer. A plaque formed from the polycarbonate composition has a reflectance of greater than or equal to 95%, as determined by reflectance measurements using a Gretag Macbeth Coloreye spectrophotometer (D65 light source, 10 degree observer, UV included) made at a wavelength of 680 nm. In an embodiment, a polycarbonate composition comprises: a polycarbonate; 7 to 20 wt % titanium dioxide; a flame retardant; and an optional UV stabilizer; wherein the polycarbonate composition has a maximum reflectance of greater than or equal to 95%. The melt volume rate as determined at 300° C. using a 1.2 kilogram weight, in accordance with ASTM D1238-04 is from 5 to 30 grams per 10 minutes.

First claim

We claim:

1. An illumination device, comprising:
an LED;
a reflector comprising a reflective surface, wherein the reflective surface comprises a composition comprising
polycarbonate;
12.5 wt % to 15 wt % titanium dioxide, based upon a total weight of the polycarbonate composition; and
an optional UV stabilizer;

wherein a plaque consisting essentially of the polycarbonate, the titanium dioxide, and the optional UV stabilizer has a reflectance of greater than or equal to 96.5% as determined by reflectance measurements using a Gretag Macbeth Coloreye spectrophotometer (D65 light source, 10 degree observer, UV included) made at a wavelength of 680 nm; and
a lens in physical contact with the reflector.

2. The device of claim 1 , wherein the composition is free of a flame retardant.

3. The device of claim 1 , wherein the maximum reflectance is greater than or equal to 97%.

4. The device of claim 1 , wherein the composition has a melt volume rate as determined at 300° C. using a 1.2-kilogram weight, in accordance with ASTM D1238-04 of 5 to 50 grams per 10 minutes.

5. The device of claim 1 , wherein the titanium dioxide has an average particle size of 30 nm to 500 nm and/or wherein the titanium dioxide comprises coated titanium dioxide, where the titanium dioxide is coated with alumina and/or polysiloxane.

6. The device of claim 1 , wherein the UV stabilizer is present and is selected from 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol, 2,2′-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one), and combinations comprising at least one of the foregoing.

7. The device of claim 1 , wherein the composition further comprises an antistatic agent in an amount of greater than 0 to 3 wt %, based upon a total weight of the composition.

8. The device of claim 1 , wherein when exposed to the LED light in a light box with 6 LED lights (GE-Tetra LED System 5 Amp max output 20 watts) for 2,000 hours, a 3.2 mm plaque formed from the composition has a color change of less than or equal to 0.5 DE.

9. The device of claim 1 , wherein the reflective surface is free of metallization.

10. A method of reflecting light comprising:
illuminating a reflective surface with light from an LED,
wherein the reflective surface comprises a polycarbonate composition comprising polycarbonate;
12.5 wt % to 15 wt % titanium dioxide, based upon a total weight of the polycarbonate composition; and
an optional UV stabilizer;

wherein a plaque consisting essentially of the polycarbonate, the titanium dioxide, and the optional UV stabilizer has a reflectance of greater than or equal to 96.5%, as determined by reflectance measurements using a Gretag Macbeth Coloreye spectrophotometer (D65 light source, 10 degree observer, UV included) made at a wavelength of 680 nm.

11. The method of claim 10 , wherein the composition is free of a flame retardant.

12. The method of claim 10 , wherein a melt volume rate of the composition as determined at 300° C. using a 1.2 kilogram weight, in accordance with ASTM D1238-04 is from 5 to 30 grams per 10 minutes.

13. The method of claim 10 , wherein the maximum reflectance is greater than or equal to 97%.

14. The method of claim 10 , wherein the composition has a melt volume rate as determined at 300° C. using a 1.2-kilogram weight, in accordance with ASTM D1238-04 of 5 to 50 grams per 10 minutes.

15. The method of claim 10 , wherein the titanium dioxide has an average particle size of 30 nm to 500 nm and/or wherein the titanium dioxide comprises coated titanium dioxide, where the titanium dioxide is coated with alumina and/or polysiloxane.

16. The method of claim 10 , wherein the UV stabilizer is present and wherein the UV stabilizer is selected from 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol, 2,2′-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one), and combinations comprising at least one of the foregoing.

17. The method of claim 10 , further comprising an antistatic agent, wherein the antistatic agent is present in an amount of greater than 0 to 3 wt %, based upon a total weight of the composition.

18. The method of claim 10 , wherein when exposed to light from the LED in a light box with 6 LED lights (GE-Tetra LED System 5 Amp max output 20 watts) for 2,000 hours, a plaque formed from the composition has a color change of less than or equal to 0.5 DE.

19. The method of claim 10 , wherein the reflective surface is free of metallization.

20. The method of claim 10 , wherein the plaque relies only on the titanium dioxide to provide the reflectance.

Assignees

• Sabic Global Technologies Bv

Inventors

• Flores Amanda Marie
• Pai-Paranjape Vandita

Classifications

• C09D169/00

  Coating compositions based on polycarbonates; Coating compositions based on derivatives of polycarbonates · CPC title

• C08K9/08

  Ingredients agglomerated by treatment with a binding agent · CPC title

• C08K9/06

  with silicon-containing compounds · CPC title

• C08K9/02

  Ingredients treated with inorganic substances · CPC title

• C08K5/42

  Sulfonic acids; Derivatives thereof · CPC title