ARTICLE COMPRISING EXPANDED TPU AND A WATER BASED 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 dispersion/solution. It has been found that a polurethane 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 water-based polyurethane urea solution/dispersion, 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 solid content of the water-based polyurethane urea solution/dispersion is in a range of from 35 to 60 wt.-%, based on the total weight of the polyurethane urea solution/dispersion.

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

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

10. The article according to claim 1, wherein the article is selected from the group consisting of a shoe sole, a seat, a car seat, a child's seat, a tube, a bicycle tube, a roll, a cabin roll, a bumper, an auto bumper, a cushion, a mattress, and 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 water-based polyurethane urea solution/dispersion on at least a part of said substrate of step 1), wherein the polyurethane urea comprises polycarbonate structural units, 3) curing said water-based polyurethane urea solution/dispersion 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 water-based polyurethane urea solution/dispersion 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 water-based polyurethane urea solution/dispersion 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 water-based polyurethane urea solution/dispersion has a viscosity of 10 to 30 seconds according to DIN EN ISO 2431.

15. A decorative coating of a substrate comprising an expanded thermoplastic polyurethane substrate coated at least in part with a water-based polyurethane urea solution/dispersion, wherein the polyurethane urea comprises polycarbonate structural units and at least one colorant.

Description

EXAMPLES

[0108] Starting Materials

TABLE-US-00001 Name of the raw material Description of the raw material Impranil DLU Aliphatic polycarbonateester- (Covestro Deutschland AG) polyether polyurethane dispersion Impranil DL 2077 XP Anionic polycarbonate polyurethane (Covestro Deutschland AG) dispersion Byk 348 Silicone surfactant for aqueous (BYK-Chemie GmbH, Wesel) coatings Byk 333 Silicone surfactant for aqueous (BYK-Chemie GmbH, Wesel) coatings Desmodur N3900 Low-viscosity, aliphatic polyisocyanate (Covestro Deutschland AG) resin based on hexamethylene diisocyanate Aquaderm-X black B-EXP Black pigment (Lanxess AG)

Example 1: Dispersion A

[0109]

TABLE-US-00002 Impranil DLU: 800 g Impranil DL 2077 XP: 200 g Byk 348 20 g Byk 333 5 g Desmodur N 3900 20 g Aquaderm-X black B-EXP 2129 50 g

Example 2: Solution/Dispersion A

[0110]

TABLE-US-00003 Impranil DLU: 700 g Impranil DL 2077 XP: 300 g Byk 348 20 g Byk 333 5 g Desmodur N 3900 20 g Aquaderm-X black B-EXP 2129 50 g

[0111] Preparation of Water-Based Polyurethane Urea Dispersion with Mixture A or B:

[0112] The mixture according to the partial amounts as mentioned above of the Impranil DLU and Impranil DL 2077 XP were stirred at 70 C. for 10 minutes. Afterwards the partial amounts as mentioned above of Byk 348 and Byk 333 were added and stirred for another 15 minutes at 70 C. Desmodur N 3900 in its partial amount was added and finally the pigment Aquaderm-X black was added. This mixture was stirred for another 10 minutes at 70 C.

[0113] The resulting dispersion A or B had a viscosity according to DIN EN ISO 2431 of 11 s.

[0114] Article According to the Invention

[0115] 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).

[0116] Dispersion A or B was applied to the cleaned expanded TPU substrate using a spray gun with an opening of 2.5 mm. 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.

[0117] 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.

[0118] 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.