Thermoplastic polycarbonate compositions with low gloss, articles made therefrom and method of manufacture
View Patent ↗A thermoplastic composition comprising a polycarbonate, an impact modifier, an aromatic vinyl copolymer, and a polyorganosiloxane has excellent mechanical properties, in addition to suitable low gloss performance. An article may be formed by molding, extruding, shaping or forming such a composition to form the article.
1. A thermoplastic composition comprising a resin composition consisting essentially of:
from 55 to 70 wt. % of a polycarbonate;
from 8 to 20 wt. % of an impact modifier comprising an elastomer-modified graft copolymer comprising (i) an elastomeric polymer substrate having a Tg less than 10° C. and (ii) a rigid polymeric superstrate grafted to the elastomeric polymer substrate;
from 15 to 25 wt. % of an aromatic vinyl copolymer; and
from 3 to 8 wt. % of a polyorganosiloxane, based on the combined weights of the polycarbonate, impact modifier, aromatic vinyl copolymer, and polyorganosiloxane;
wherein the aromatic vinyl copolymer comprises ungrafted SAN; and
wherein the thermoplastic composition has a surface gloss level of less than 65 when measured on a smooth surface according to ASTM D2457 at 60° using a Gardner Gloss Meter and 3 millimeter color chips.
2. The thermoplastic composition of claim 1 , wherein the polyorganosiloxane has repeating subunits of the general Formula:
wherein each occurrence of R is same or different, and is a C 1-13 monovalent organic radical, and g is from 1 to about 30.
3. The thermoplastic composition of claim 2 , wherein the polyorganosiloxane is a polyorganosilsesquioxane.
4. The thermoplastic composition of claim 3 , wherein the polyorganosilsesquioxane is a polymethylsilsesquioxane.
5. The thermoplastic composition of claim 1 , wherein a 3.2 mm thick molded sample comprising the thermoplastic composition has a notched Izod impact strength of greater than or equal to about 20 kJ/m determined in accordance with ISO 180U at 23° C.
6. An article comprising the composition of claim 1 .
7. A method of manufacture of an article comprising molding, extruding, or shaping the composition of claim 1 .
8. A thermoplastic composition comprising a resin composition consisting essentially of:
from 55 to 70 wt. % of a polycarbonate;
from 8 to 20 wt. % of an impact modifier comprising an elastomer-modified graft copolymer comprising (i) an elastomeric polymer substrate having a Tg less than 10° C. and (ii) a rigid polymeric superstrate grafted to the elastomeric polymer substrate;
from 15 to 25 wt. % of an aromatic vinyl copolymer; and
from 3 to 8 wt. % of a polyorganosiloxane, based on the combined weights of the polycarbonate, impact modifier, aromatic vinyl copolymer, and polyorganosiloxane;
wherein the thermoplastic composition has a surface gloss level of less than 65 when measured on a smooth surface according to ASTM D2457 at 60° using a Gardner Gloss Meter and 3 millimeter color chips; and
wherein a 4 mm thick molded sample comprising the thermoplastic composition has a Tensile Elongation at Break of greater than 60%.
9. The thermoplastic composition of claim 8 , wherein the polyorganosiloxane has repeating subunits of the general Formula:
wherein each occurrence of R is same or different, and is a C 1-13 monovalent organic radical, and g is from 1 to about 30.
10. The thermoplastic composition of claim 9 , wherein the polyorganosiloxane is a polyorganosilsesquioxane.
11. The thermoplastic composition of claim 10 , wherein the polyorganosilsesquioxane is a polymethylsilsesquioxane.
12. The thermoplastic composition of claim 8 , wherein a 3.2 mm thick molded sample comprising the thermoplastic composition has a notched Izod impact strength of greater than or equal to about 20 kJ/m determined in accordance with ISO 180U at 23° C.
13. An article comprising the composition of claim 8 .
14. A method of manufacture of an article comprising molding, extruding, or shaping the composition of claim 8 .