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EP-3908630-B1 - THERMOPLASTIC POLYURETHANE COMPOUNDS EXHIBITING ENHANCED STAIN RESISTANCE

EP3908630B1EP 3908630 B1EP3908630 B1EP 3908630B1EP-3908630-B1

Inventors

  • GU, JIREN

Dates

Publication Date
20260513
Application Date
20200107

Claims (11)

  1. An accessory for an electronic device, the accessory comprising a thermoplastic article molded from a thermoplastic polyurethane compound, the thermoplastic polyurethane compound comprising: 100 parts by weight of thermoplastic polyurethane selected from blends of aliphatic polycaprolactone thermoplastic polyurethane and aromatic thermoplastic polyurethane selected from aromatic polyester thermoplastic polyurethane, aromatic polyether thermoplastic polyurethane, and combinations thereof, wherein from about 10 to about 50 parts by weight is the aliphatic polycaprolactone thermoplastic polyurethane and from about 50 to about 90 parts by weight is the aromatic thermoplastic polyurethane; wherein the thermoplastic polyurethane compound is free of aromatic polycaprolactone thermoplastic polyurethane; wherein the thermoplastic article achieves a rating of 2 or better according to Blue Jean Abrasion Test; and wherein the accessory is a protective case for a handheld electronic device.
  2. An accessory according to claim 1, wherein from about 25 to about 50 parts by weight is the aromatic polycaprolactone thermoplastic polyurethane and from about 50 to about 75 parts by weight is the other aromatic thermoplastic polyurethane, and wherein the thermoplastic article achieves a rating of 1 according to Blue Jean Abrasion Test.
  3. An accessory according to Claim 1 or Claim 2, wherein the thermoplastic polyurethane compound further comprises additives selected from antioxidants and stabilizers; colorants; mold release agents; processing aids; ultraviolet light absorbers; and combinations thereof.
  4. An accessory according to any one of Claims 1 to 3, wherein the thermoplastic polyurethane compound further comprises secondary polymer selected from styrenic block copolymers, thermoplastic vulcanizates, polyolefin elastomers, copolyesters, and combinations thereof.
  5. An accessory according to Claim 4, wherein the thermoplastic polyurethane compound further comprises plasticizer.
  6. An accessory according to any one of Claims 1 to 5, wherein the thermoplastic polyurethane compound is free of aliphatic polyester thermoplastic polyurethane and aliphatic polyether thermoplastic polyurethane.
  7. An accessory according to any one of Claims 1 to 6, wherein the thermoplastic polyurethane compound further comprises from about 0.1 to about 2 parts by weight of ultraviolet light absorber; and wherein the thermoplastic article, after subjected to QUV Test, achieves a Delta E of less than about 4.5 and a Yellow Index of less than about 6.5.
  8. An accessory according to any one of Claims 1 to 7, comprising an overmolded article comprising: (a) on overmold portion comprising said thermoplastic polyurethane compound; 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.
  9. A method of improving resistance to Blue Jean Staining for a thermoplastic article molded from a thermoplastic polyurethane compound comprising 100 parts by weight of thermoplastic polyurethane, the method comprising the step of: selecting the thermoplastic polyurethane from blends of aliphatic polycaprolactone thermoplastic polyurethane and aromatic thermoplastic polyurethane selected from aromatic polyester thermoplastic polyurethane, aromatic polyether thermoplastic polyurethane, and combinations thereof, wherein from about 10 to about 50 parts by weight is the aliphatic polycaprolactone thermoplastic polyurethane and from about 50 to about 90 parts by weight is the aromatic thermoplastic polyurethane; wherein the thermoplastic polyurethane compound is free of aromatic polycaprolactone thermoplastic polyurethane; wherein the thermoplastic article achieves a rating of 2 or better according to Blue Jean Abrasion Test; and wherein the thermoplastic article is a protective case for a handheld electronic device.
  10. The method of Claim 9, wherein from about 25 to about 50 parts by weight is the aromatic polycaprolactone thermoplastic polyurethane and from about 50 to about 75 parts by weight is the other aromatic thermoplastic polyurethane, and wherein the thermoplastic article achieves a rating of 1 according to Blue Jean Abrasion Test.
  11. The method of Claim 9 or Claim 10, wherein the thermoplastic polyurethane compound is free of aliphatic polyester thermoplastic polyurethane and aliphatic polyether thermoplastic polyurethane.

Description

CLAIM OF PRIORITY This application claims the benefit of U.S. Provisional Patent Application Serial No. 62/790,319 bearing Attorney Docket Number 12019004 and filed on January 9, 2019. FIELD OF THE INVENTION This invention relates to thermoplastic polyurethane compounds and thermoplastic articles formed therefrom that have enhanced resistance to abrasion and staining while also exhibiting good clarity and other desirable properties. BACKGROUND OF THE INVENTION Demand exists for polymeric materials that are useful for making protective cases and other components or accessories for personal electronic devices such as smart phones, tablets, and handheld computers. Protective cases for personal electronic devices typically require good aesthetics such as "look" and "feel" that are desirable to consumers. For example, some consumers prefer the look of protective cases that are relatively clear in appearance or that are lightly or brightly colored. Further, some consumers prefer the feel of protective cases that are relative soft to the touch without being sticky or tacky. Thermoplastic elastomers (TPE), which are polymeric materials that exhibit elasticity while remaining thermoplastic, can be useful for making protective cases for personal electronic devices. TPEs can include styrenic block copolymers (SBC), thermoplastic vulcanizates (TPV), thermoplastic polyolefins (TPO), copolyesters (COPE), thermoplastic polyurethanes (TPU), copolyamides (COPA), olefinic block copolymers (OBC). Although certain TPEs, such as conventional TPUs, can offer good clarity and other properties desirable for making protective cases for personal electronic devices, drawbacks still exist. For example, protective cases made from conventional TPUs can suffer from poor resistance to abrasion and staining when personal electronic devices are placed by users in garments or clothing articles made from denim or other dyed fabrics, such as in a pocket of blue jeans. Disadvantageously, it is possible for such protective cases to be abraded by the fabric and stained by dye that transfers from the fabric. Such abrasion and staining is especially problematic when protective cases are clear or lightly or brightly colored. US 2013/101755 A1 discloses an alignment film that includes a first pre-tilt functional group, a second pre-tilt functional group and a first vertical alignment functional group, which are linked to polysiloxane on a substrate. The first vertical alignment functional group includes a cyclic compound and is aligned substantially perpendicularly to the substrate. The first pre-tilt functional group is cross-linked to the second pre-tilt functional group and tilted with respect to the substrate. SUMMARY OF THE INVENTION Consequently, a need exists for thermoplastic polyurethane compounds and thermoplastic articles molded therefrom that have enhanced resistance to abrasion and staining while also exhibiting good clarity and other desirable properties. The aforementioned needs are met by one or more aspects of the present invention. Surprisingly, it has been found that, by selecting blends of aliphatic polycaprolactone thermoplastic polyurethane and aromatic thermoplastic polyurethane selected from aromatic polyester thermoplastic polyurethane, aromatic polyether thermoplastic polyurethane, and combinations thereof, it is possible to provide thermoplastic polyurethane compounds and thermoplastic articles formed therefrom having enhanced resistance to abrasion and staining while also exhibiting good clarity and other desirable properties. Disclosed herein are thermoplastic polyurethane compounds including blends of aliphatic polycaprolactone thermoplastic polyurethane and aromatic thermoplastic polyurethane selected from aromatic polyester thermoplastic polyurethane, aromatic polyether thermoplastic polyurethane, and combinations thereof, wherein from about 10 to about 50 parts by weight is the aliphatic polycaprolactone thermoplastic polyurethane and from about 50 to about 90 parts by weight is the aromatic thermoplastic polyurethane. Some aspects of the invention are directed to an accessory for an electronic device, the accessory comprising a thermos plastic article molded from a thermoplastic polyurethane compound as described in claim 1. The thermoplastic articles molded from thermoplastic polyurethane compounds including blends of aliphatic polycaprolactone thermoplastic polyurethane and aromatic thermoplastic polyurethane selected from aromatic polyester thermoplastic polyurethane, aromatic polyether thermoplastic polyurethane, and combinations thereof. Also disclosed herein are methods of making thermoplastic articles. The methods include steps of providing thermoplastic polyurethane compounds as described herein, and molding the thermoplastic polyurethane compounds to provide the thermoplastic articles. Further aspects of the invention are directed to methods of improving resistance to Blue Jean Staining for thermoplastic art