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EP-3908629-B1 - THERMOPLASTIC POLYURETHANE COMPOUNDS EXHIBITING ENHANCED STAIN RESISTANCE

EP3908629B1EP 3908629 B1EP3908629 B1EP 3908629B1EP-3908629-B1

Inventors

  • GU, JIREN

Dates

Publication Date
20260513
Application Date
20200107

Claims (13)

  1. 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 aromatic polycaprolactone thermoplastic polyurethane and other aromatic thermoplastic polyurethane selected from aromatic polyester thermoplastic polyurethane, aromatic polyether thermoplastic polyurethane, and combinations thereof, wherein from about 20 to about 99 parts by weight is the aromatic polycaprolactone thermoplastic polyurethane and from about 1 to about 80 parts by weight is the other aromatic thermoplastic polyurethane; wherein the thermoplastic polyurethane compound is free of aliphatic 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 an accessory for an electronic device.
  2. The thermoplastic article of Claim 1, wherein from about 60 to about 99 parts by weight is the aromatic polycaprolactone thermoplastic polyurethane and from about 1 to about 40 parts by weight is the other aromatic thermoplastic polyurethane.
  3. The thermoplastic article of 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. The thermoplastic article of 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. The thermoplastic article of Claim 4, wherein the thermoplastic polyurethane compound further comprises plasticizer.
  6. The thermoplastic article of 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. The thermoplastic article of any one of Claims 1 to 6, wherein the thermoplastic article, after subjected to QUV Test, achieves a Delta E from about 7.5 to about 20 and a Yellow Index from about 11.5 to about 30.
  8. The thermoplastic article of any one of Claims 1 to 7, wherein the accessory is a protective case for a handheld electronic device.
  9. The thermoplastic article of any one of Claims 1 to 8, wherein said article is an overmolded article comprising: (a) an 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.
  10. 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 aromatic polycaprolactone thermoplastic polyurethane and other aromatic thermoplastic polyurethane selected from aromatic polyester thermoplastic polyurethane, aromatic polyether thermoplastic polyurethane, and combinations thereof, wherein from about 20 to about 99 parts by weight is the aromatic polycaprolactone thermoplastic polyurethane and from about 1 to about 80 parts by weight is the other aromatic thermoplastic polyurethane; wherein the thermoplastic polyurethane compound is free of aliphatic 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 an accessory for an electronic device.
  11. The method of Claim 10, wherein from about 60 to about 99 parts by weight is the aromatic polycaprolactone thermoplastic polyurethane and from about 1 to about 40 parts by weight is the other aromatic thermoplastic polyurethane.
  12. The method of Claim 10 or Claim 11, wherein the thermoplastic polyurethane compound is free of aliphatic polyester thermoplastic polyurethane and aliphatic polyether thermoplastic polyurethane.
  13. The method of any one of Claims 10 to 12, wherein the thermoplastic article is a protective case or portion thereof for a handheld electronic device.

Description

CLAIM OF PRIORITY This application claims the benefit of U.S. Provisional Patent Application Serial No. 62/790,311 bearing Attorney Docket Number 12019003 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 6342047 B1 describes an indwelling catheter made of a blend of a plurality of polyurethane resins. WO 2018/164235 A1 describes an indwelling catheter comprising a polyurethane resin, wherein the polyurethane resin contains an aromatic diisocyanate, an aliphatic diol, an aromatic polyglycol or an aliphatic polyglycol as a main component. WO 95/13307 A1 describes a multi-component composition comprising from about 5 % to about 95 % a polyurethane formed by heating a reaction mixture comprising at least one isocyanate having a functionality less than about 2, at least one long chain polyol, at least one chain extender, and at least one plasticizer, or a thermoplastic polymer alloy, and at least another thermoplastic material selected from the group consisting of polyamide, polyurethane, ethyl vinyl acetate, polyurethane ester and polyvinyl chloride. WO 95/00590 A2 describes a thermoplastic urethane elastomeric alloy obtained by melt compounding at least one first component that is a polyurethane elastomer having at least one plasticizer reacted therein, with at least one second component that is another thermoplastic elastomer not within the definition of the first component. US2009/149622 A1 describes a transparent thermoplastic polyurethane (TPU) comprising structural units of: a.) a diisocyanate; b.1) a polyester diol and b.2) a specific polyether diol and c.) a chain extender. WO 2018/029131 A1 describes a porous membrane, process for the manufacture thereof and uses thereof, the porous membrane comprises at least one layer obtained from a composition comprising at least one fluorinated polyurethane. 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 aromatic polycaprolactone thermoplastic polyurethane and other 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 aromatic polycaprolactone thermoplastic polyurethane and other aromatic thermoplastic polyurethane selected from aromatic polyester thermoplastic polyurethane, aromatic polyether thermoplastic polyurethane,