HIGH HARDNESS THERMOPLASTIC POLYURETHANE MATERIALS HAVING GLASS TRANSITION TEMPERATURES ABOVE ROOM TEMPERATURE
A reactive formulation and method for forming a thermoplastic polyurethane (TPU) having a glass transition temperature (Tg) above room temperature, preferably a Tg higher than 40° C., more preferably higher than 55° C., a flexural modulus in the range 300-15000 MPa-(measured according to ISO 178), most preferably in the range 1500-2700 MPa and a tensile strength at break (according to DIN 53504) in the range of 5 up to 150 MPa is disclosed. Said reactive formulation comprising at least an isocyanate composition and an isocyanate-reactive composition comprising at least an aromatic dicarboxylic acid based diol chain extender having a molecular weight<500 g/mol and optionally fillers. Furthermore, a TPU material having a glass transition temperature (Tg)>room temperature and a flexural modulus in the range 300-15000 MPa (measured according to ISO 178) is disclosed which is thermally recyclable and optionally made from a terephthalic acid based polyester diol chain extender made from recycled PET.
1 . A reactive formulation for forming a thermoplastic polyurethane (TPU) having a shore D hardness (measured according to DIN ISO 7619-2) in the range 50-100 and a glass transition temperature (Tg, measured according to ISO 11357-2:2020) above room temperature, said reactive formulation comprising at least:
An isocyanate composition comprising at least one difunctional isocyanate compound, and
An isocyanate-reactive composition comprising at least 10 wt % isocyanate-reactive compounds selected from at least one aromatic dicarboxylic acid based diol chain extender selected from terephthalic acid based polyester diol chain extender made from recycled PET having a molecular weight<500 g/mol calculated on the total weight of all chain extenders in the isocyanate reactive composition, and
Optionally a catalyst compound, and
Optionally further additives and/or fillers
Wherein the reactive formulation has a hardblock content >70 wt % based on the total weight of the isocyanate composition and isocyanate-reactive composition, the isocyanate index of the reactive formulation is in the range 75 up to 125 and the number average isocyanate functionality and the number average hydroxy functionality of the reactive formulation is in the range of 1.8 up to 2.5.
2 . The reactive formulation according to claim 1 , wherein the isocyanate-reactive composition has an hydroxy functionality in the range 1.8 up to 2.4 and comprising at least 20 wt % of aromatic carboxylic acid based diol chain extenders having a molecular weight<500 g/mol calculated on the total weight of all chain extenders in the isocyanate reactive composition.
3 . The reactive formulation according to claim 1 , wherein the TPU has a Tg.
4 . The reactive formulation according to claim 1 , wherein the isocyanate-reactive composition comprises aromatic and aliphatic based diols such that at least 20 wt % of the diols are selected from aromatic dicarboxylic acid based diols based on the total weight of the isocyanate reactive composition.
5 . The reactive formulation according to claim 1 , wherein said aromatic dicarboxylic acid based diol chain extender is based on phthalic acid selected from o-phthalic acid, m-phthalic acid and/or p-phthalic acid.
6 . The reactive formulation according to claim 1 , wherein the reactive formulation contains less than 1 wt % of water.
7 . The reactive formulation according to claim 1 , wherein the reactive formulation contains no water.
8 . The reactive formulation according to claim 1 , wherein the isocyanate composition comprises aromatic isocyanate compounds selected from difunctional diphenylmethane diisocyanates isomers which are present in the reactive formulation in an amount >40 wt % calculated on the total weight of the reactive formulation excluding any additives and fillers.
9 . The reactive formulation according to claim 1 wherein the hardblock content of the reactive formulation is >75 wt %.
10 . The reactive formulation according to claim 1 , wherein the number average functionality of isocyanate-reactive compounds and/or isocyanate compounds and/or the complete reactive formulation (including all isocyanate and isocyanate-reactive compounds) is in a range of 1.8 up to 2.5.
11 . The reactive foam formulation according to claim 1 , wherein the isocyanate composition has an NCO value in the range 3 up to 50.
12 . The reactive formulation according to claim 1 , wherein the isocyanate composition is comprised of at least 80 wt % 4,4′-diphenylmethane diisocyanates calculated on the total weight of the isocyanate composition.
13 . The reactive formulation according to claim 1 , wherein the isocyanate index of the reactive formulation is in a range of 80 up to 120.
14 . The reactive formulation according to claim 1 , wherein the aromatic dicarboxylic acid based diol chain extender has a molecular weight in the range 45 g/mol up to 500 g/mol.
15 . A process for making a thermally recyclable TPU made by combining and reacting the compounds of the reactive formulation according to claim 1 .
16 . A thermoplastic polyurethane (TPU) material made by combining and reacting the compounds of the reactive formulation according to claim 1 , wherein the TPU material has a Tg>room temperature, a flexural modulus in a range of 300-15000 MPa (measured according to ISO 178) and a tensile strength at break (according to DIN 53504) in a range of 5 up to 150 MPa.
17 . The TPU material according to claim 16 made using a reactive formulation wherein the aromatic dicarboxylic acid based diol chain extender is a terephthalic acid based polyester diol chain extender made from recycled PET and said TPU material comprises a recycled content of >2 wt % based on the total weight of the TPU material excluding any fillers.