ARTICLE COMPRISING EXPANDED TPU AND A COATING

Abstract

The present invention relates to an article comprising expanded thermoplastic polyurethane as a substrate and a specific polyurethane urea coating on said substrate, as well as footwear, a process for producing the article and a use of a polyurethane urea solution. It has been found that a polyurethane urea coating comprising polycarbonate structural units strongly binds to expanded TPU substrates and maintains the intrinsic properties of the expanded TPU.

Claims

1. An article comprising expanded thermoplastic polyurethane as a substrate and a coating on at least a part of said substrate, wherein the coating is obtained by curing a polyurethane urea solution comprising at least one organic solvent, wherein the polyurethane urea comprises polycarbonate structural units.

2. The article according to claim 1, wherein the expanded thermoplastic polyurethane comprises at least one polyether.

3. The article according to claim 1, wherein the expanded thermoplastic polyurethane additionally comprises at least one lubricant.

4. The article according to claim 4, wherein the at least one lubricant comprises talc, a metal compound, silica, a salt of a C10 to C22 carboxylic acid, an ester of a C10 to C22 carboxylic acid, a silicone oil, polytetrafluoroethylene, or a combination of at least two thereof.

5. The article according to claim 1, wherein the polyurethane urea is obtained by a reaction of at least the following educts: a) a polycarbonatediol, b) an aliphatic or cycloaliphatic diamine or hydrazine, as a chain extender, and c) an aliphatic, cycloaliphatic or aromatic diisocyanate.

6. The article according to claim 1, wherein the polyurethane urea comprises alkoxysilane structural units.

7. The article according to claim 1, wherein the at least one organic solvent comprises toluene, isopropanol, 1-methoxypropan-2-ol, 1-methoxypropylacetat, gamma-butyrolacton, propylene glycol monomethyl ether, 2-butanone, ethyl acetate, or a combination of at least two thereof.

8. The article according to claim 1, wherein the polyurethane urea solution additionally comprises at least one colorant.

9. The article according to claim 1, wherein the polyurethane urea solution additionally comprises at least one polyisocyanate.

10. The article according to claim 1, wherein the article comprises a shoe sole, a seat, a tube, a roll, a bumper, a cushion, a mattress, or a combination of at least two thereof.

11. Footwear comprising the article according to claim 1.

12. A process for the production of the article according to claim 1 comprising the steps of: 1) providing a substrate comprising expanded thermoplastic polyurethane, 2) applying a polyurethane urea solution comprising at least one organic solvent on at least a part of said substrate of step 1), wherein the polyurethane urea comprises polycarbonate structural units, 3) curing said polyurethane urea solution of step 2) in order to obtain a coating, and 4) optionally repeating steps 2) and 3) at least one time, wherein, when repeating step 2) the polyurethane urea solution comprising at least one organic solvent is applied to the cured coating obtained in step 3) or in repeated step 3).

13. The process of claim 12, wherein in step 2) the polyurethane urea solution comprising at least one organic solvent is applied to the substrate by brushing, spraying, rolling, roll coating, slot coating, dipping, printing or a combination thereof.

14. The process according to claim 12, wherein the polyurethane urea solution has a viscosity of from 50 to 40 000 mPas according to DIN EN ISO 3219/A.3.

15. A decorative coating of a substrate comprising an expanded thermoplastic polyurethane substrate coated with a polyurethane urea solution comprising at least one organic solvent and at least one colorant, wherein the polyurethane urea comprises polycarbonate structural units.

Description

EXAMPLES

Example 1 with Solution A

[0094]

TABLE-US-00001 Impranil 2610* (Covestro Deutschland AG) 23.44 parts by weight Propylene glycol monomethyl ether (Lanxess 11.72 parts by weight Deutschland GmbH) 2-Butanone (Lanxess Deutschland GmbH) 62.5 parts by weight Bayderm black CO (pigment) (Lanxess 2.34 parts by weight Deutschland GmbH) Desmodur N 75 MPA/x-cn** (Covestro 3 parts by weight Deutschland AG) *aliphatic polyurethane urea comprising polycarbonate structural units, 30% solid content in 1-methoxypropylacetat/gamma-butyrolacton/isopropanol/1-methoxypropan-2-ol 7:23:20:20 **biuret structure based on hexamethylene diisocyanate

[0095] In order to obtain a polyurethane urea solution A firstly Impranil 2610 was homogenously mixed with propylene glycol monomethyl ether. Subsequently, 2-butanone was slowly added while stirring. Then the pigment was added.

[0096] Finally, Desmodur N 75 MPA/x-cn was added and dispersed in the solution.

[0097] An expanded TPU shoe sole obtained according to example 1 in WO 2007/045586 A1 was cleaned by 2 ml/cm.sup.2 of PUSR500 of Wrth (Adolf Wrth GmbH & Co. KG, Knzelsau-Gaisbach, Germany).

[0098] Solution A was applied to the cleaned expanded TPU substrate using a conventional spray gun The white substrate was coated until no white color of this substrate was visible any longer. The coated substrate was cured at 70 C. for 10 min.

[0099] The adhesion of the coating to the substrate was tested using a manual rubber/EVA laminating process. In this test a human tried by hand to separate the coating from the substrate by hand utilizing its entire force. No lamination of the coating could be determined.

Example 2 with Solution B

[0100]

TABLE-US-00002 Impranil 2610* 24 parts by weight Propylene glycol monomethyl ether 12 parts by weight 2-Butanone 64 parts by weight Desmodur N 75 MPA/x-cn** 1 parts by weight *aliphatic polyurethane urea comprising polycarbonate structural units, 30% solid content in 1-methoxypropylacetat/gamma-butyrolacton/isopropanol/1-methoxypropan-2-ol 7:23:20:20 **biuret structure based on hexamethylene diisocyanate

[0101] In order to obtain a polyurethane urea solution firstly Impranil 2610 was homogenously mixed with propylene glycol monomethyl ether. Subsequently, 2-butanone was slowly added while stirring.

[0102] Finally, the additionally polyisocyanate was added and dispersed in the solution.

[0103] Solution B was applied to the expanded TPU substrate coated with a coating obtained by curing solution A using a spray gun. The coated substrate was cured at 70 C. for 10 min.

[0104] The adhesion of the coating to the substrate was tested using a manual rubber/EVA laminating process. In this test a human tried by hand to separate the coating from the substrate by hand utilizing its entire force. No lamination of the coating could be determined.

[0105] In both examples 1 and 2, after drying of the coated substrate a surface with a dry touch is achieved which is flexible and will not peel off when utilized. As utilization a normal use of a shoe or other article of daily life is possible. The surface can be changed in color by adding different pigments.