Thermoplastic polyurethane compounds exhibiting enhanced stain resistance
Thermoplastic articles are molded from thermoplastic polyurethane compounds including aromatic polycaprolactone thermoplastic polyurethane. The thermoplastic articles exhibit enhanced stain resistance, as represented by achieving a rating of 1 according to Blue Jean Abrasion Test, relative to thermoplastic articles molded from thermoplastic polyurethane compounds including other types of thermoplastic polyurethanes, while also having good clarity (i.e., low haze) and other desirable properties. The thermoplastic articles can be especially useful as protective cases for handheld electronic devices.
1. An accessory for an electronic device, the accessory comprising a molded thermoplastic article molded from a thermoplastic polyurethane compound, the thermoplastic polyurethane compound consisting of:
100 parts by weight of aromatic polycaprolactone thermoplastic polyurethane;
0.1 to 10 parts of an additive per 100 parts by weight of the aromatic polycaprolactone thermoplastic polyurethane, wherein the additive includes at least one mold release agent;
0 to 150 parts of a secondary polymer per 100 parts by weight of the aromatic polycaprolactone thermoplastic polyurethane, wherein the secondary polymer is selected from the group consisting of styrenic block copolymers, thermoplastic vulcanizates, polyolefin elastomers, copolyesters, and combinations thereof;
0 to 300 parts of a plasticizer per 100 parts by weight of the aromatic polycaprolactone thermoplastic polyurethane;
wherein the thermoplastic polyurethane compound is free of aliphatic polycaprolactone thermoplastic polyurethane; and
wherein the molded thermoplastic article achieves a rating of 1 according to Blue Jean Abrasion Test.
2. The accessory of claim 1 , wherein the accessory is a protective case for a handheld electronic device.
3. An overmolded article comprising:
(a) on overmold portion comprising the thermoplastic article of claim 1 ; and
(b) a substrate portion molded from a thermoplastic resin compound;
wherein the overmold portion is bonded onto the substrate portion at a bond interface, and the bond interface is free of adhesive.
4. The accessory for an electronic device of claim 1 , wherein the additive further comprises one or more additives selected from antioxidants and stabilizers; colorants; processing aids; ultraviolet light absorbers; and combinations thereof.
5. The accessory for an electronic device of claim 1 , wherein the thermoplastic polyurethane compound is free of aromatic polyester thermoplastic polyurethane and aromatic polyether thermoplastic polyurethane.
6. The accessory for an electronic device of claim 1 , wherein the thermoplastic polyurethane compound is free of aliphatic polyester thermoplastic polyurethane and aliphatic polyether thermoplastic polyurethane.
7. The accessory for an electronic device of claim 1 , wherein the thermoplastic article, after subjected to QUV Test, achieves a Delta E from 5.5 to 30 and a Yellow Index from 8.5 to 40.