Transparent Thin-Wall Scratch-Resistant Article
A plastic article is described having a substrate of a substantially transparent substrate having a thickness of from 0.2 mm to 3.0 mm, and including a thermoplastic composition comprising a polycarbonate and having a melt flow index as defined by ASTM D1238 of 10 g/10 min. to 50 g/10 min. at 300° C. and a 1.2 kg load, the thermoplastic composition including a polycarbonate, the thermoplastic composition comprising 20 mol % to 80 mol % of specified cyclohexylidene-bridged carbonate units and 80 mol % to 20 mol % of specified other carbonate units. The substrate has a hard coat thereon that provides the article with a pencil hardness of at least 5H as determined according to JIS K5400 using a 0.75 kgf load.
1 . A plastic article, comprising
a substantially transparent substrate having a thickness of from 0.2 mm to 3.0 mm, and comprising a thermoplastic composition comprising a polycarbonate and having a melt flow index as defined by ASTM D1238 of 10 g/10 min. to 50 g/10 min. at 300° C. and a 1.2 kg load, said thermoplastic composition comprising 20 mol % to 80 mol % of carbonate units represented by the formula (I)
wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 each independently represents hydrogen or C 1-6 alkyl, and 80 mol % to 20 mol % of carbonate units represented by the formula (II)
wherein at least 60 percent of the total number of R 1 groups contain aromatic moieties and the balance thereof are aliphatic, alicyclic, or aromatic, wherein said mol % values are based on the total number of carbonate units in the polymer composition; and
a hard coat disposed over a surface of said transparent substrate, said hard coat providing said article with a pencil hardness of at least 5H as determined according to JIS K5400 using a 0.75 kgf load.
2 . The article of claim 1 , wherein the thermoplastic composition further comprises a flow promoting additive in an amount of 0.05 to 1 wt. %, based on the weight of the thermoplastic composition.
3 . The article of claim 2 , wherein said flow promoting additive is a fatty amide or imide compound having from 8 to 35 carbon atoms.
4 . The article of claim 3 , wherein said flow promoting additive is a bis-imide or a monounsaturated fatty amide having from 18 to 35 carbon atoms.
5 . The article of claim 4 , wherein said flow promoting additive is erucamide or C 17 H 35 —C(O)—NH—CH 2 —NH—C(O)—C 17 H 35 .
6 . The article of claim 1 , wherein the units of formula (II) are not within the scope of formula (I).
7 . The article of claim 1 , wherein the thermoplastic composition comprises a plurality of different carbonate units with the scope of formula (I), a plurality of different carbonate units with the scope of formula (II), or a plurality of different carbonate units with the scope of formula (I) and a plurality of different carbonate units with the scope of formula (II).
8 . The article of claim 1 , wherein said thermoplastic composition comprises a first polycarbonate comprising units of formula (I) and optionally units of formula (II), and a second polycarbonate comprising units of formula (II).
9 . The article of claim 1 , wherein said hard coat provides the article with a pencil hardness of at least 6H.
10 . The article of claim 9 , wherein said hard coat provides the article with a pencil hardness of at least 7H.
11 . The article of claim 1 , wherein said thermoplastic composition comprises from 30 mol % to 80 mol % of units represented by formula (I) and from 70 mol % to 20 mol % of one or more units represented by formula (II).
12 . The article of claim 11 , wherein said thermoplastic composition comprises from 40 mol % to 80 mol % of units represented by formula (I) and from 60 mol % to 20 mol % of one or more units represented by formula (II).
13 . The article of claim 1 , wherein said thermoplastic composition has a melt flow index of 14 g/10 min. to 50 g/10 min.
14 . The article of claim 13 , wherein said thermoplastic composition has a melt flow index of 20 g/10 min. to 50 g/10 min.
15 . The article of claim 1 , wherein said substrate has a thickness of 0.5 mm to 1.5 mm.
16 . The article of claim 1 , wherein the cured hard coat has a thickness of 10 μm to 50 μm.
17 . The article of claim 16 , wherein the cured hard coat has a thickness of 14 μm to 40 μm.
18 . The article of claim 1 , wherein the article has a light transmittance of at least 85% according to ASTM D 1003.
19 . The article of claim 18 , wherein the article has a light transmittance of at least 87%.
20 . The article of claim 19 , wherein the article has a light transmittance of at least 89%.
21 . The article of claim 1 , wherein the article has a haze no greater than 4 according to ASTM D 1003.
22 . The article of claim 21 , wherein the article has a haze no greater than 3.
23 . The article of claim 22 , wherein the article has a haze no greater than 1.
24 . The article of claim 1 , wherein R 1 and R 6 are each methyl.
25 . The article of claim 1 , wherein R 1 -R 6 each represents hydrogen.
26 . The article of claim 1 that is an electronic device display screen cover, electronic device touch screen, or electronic device keypad.
27 . The article of claim 26 , wherein the electronic device is a mobile phone or a portable media player.
28 . A plastic article, comprising
a substantially transparent substrate having a thickness of from 0.2 mm to 1.5 mm, and comprising a thermoplastic composition comprising a polycarbonate and a flow promoting additive, and having a melt flow index as defined by ASTM D1238 of 10 g/10 min. to 50 g/10 min. at 300° C. and a 1.2 kg load, said thermoplastic composition comprising 20 mol % to 80 mol % of carbonate units represented by the formula (I)
wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 each independently represents hydrogen or C 1-6 alkyl, and 80 mol % to 20 mol % of carbonate units represented by the formula (II)
wherein at least 60 percent of the total number of R 1 groups contain aromatic moieties and the balance thereof are aliphatic, alicyclic, or aromatic, wherein said mol % values are based on the total number of carbonate units in the polymer composition; and
a hard coat disposed over a surface of said transparent substrate, said hard coat providing said article with a pencil hardness of at least 5H as determined according to JIS K5400 using a 0.75 kgf load.
29 . The article of claim 28 , wherein the flow promoting additive in an amount of 0.05 to 1 wt %, based on the weight of the thermoplastic composition.
30 . The article of claim 29 , wherein the flow promoting additive in an amount of 0.1 to 0.05 wt %, based on the weight of the thermoplastic composition.
31 . The article of claim 28 , wherein said flow promoting additive is a fatty amide or imide compound having from 8 to 35 carbon atoms.
32 . The article of claim 31 , wherein said flow promoting additive is a bis-imide or a monounsaturated fatty amide having from 18 to 35 carbon atoms.
33 . The article of claim 32 , wherein said flow promoting additive is erucamide or C 17 H 35 —C(O)—NH—CH 2 —NH—C(O)—C 17 H 35 .
34 . A method of making the article of claim 1 , comprising:
injection molding the thermoplastic composition to form the substantially transparent substrate;
applying a layer of a hard-coat coating composition to a surface of said transparent sheet; and
curing said coating composition to form the hard coat.
35 . The method of claim 34 , wherein the coating composition is cured with ultraviolet radiation.
36 . The method of claim 34 , wherein the coating composition is cured with heat.
37 . The method of claim 34 , wherein the coating composition is cured with ultraviolet radiation and heat.
38 . The method of claim 34 , wherein the thermoplastic composition further comprises a flow promoting additive in an amount of 0.05 to 1 wt. %, based on the weight of the thermoplastic composition.
39 . The method of claim 38 , wherein said flow promoting additive is a bis-imide or a monounsaturated fatty amide having from 18 to 35 carbon atoms.
40 . The method of claim 34 , wherein the units of formula (II) are not within the scope of formula (I).
41 . The method of claim 34 , wherein said hard coat provides the article with a pencil hardness of at least 6H.
42 . The method of claim 41 , wherein said hard coat provides the article with a pencil hardness of at least 7H.
43 . The method of claim 34 , wherein the article has a light transmittance of at least 85% according to ASTM D 1003.