Process for the preparation of self-extinguishing thermoplastic polyurethanes

1. A one-shot process for the preparation of thermoplastically processable polyurethane elastomers (TPU) having self-extinguishing properties, comprising reacting

A) at least one organic diisocyanate with

B) at least one polyol having on average at least 1.8 and at most 3.0 Zerewitinoff-active hydrogen atoms and a number-average molecular weight M n of from about 450 to about 10,000,

C) at least one low molecular weight polyol or polyamine having on average at least 1.8 and at most 3.0 Zerewitinoff-active hydrogen atoms and a number-average molecular weight M n of from about 60 to about 400 as a chain lengthener and

D) at least one organic phosphorus-containing compound based on phosphine oxide having on average at least 1,5 and at most 3.0 Zerewitinoff-active hydrogen atoms and a number-average molecular weight M n of from about 60 to about 10,000 in an amount of from about 0.1 to about 20 wt. %, based on the total amount of TPU, with the following structural formula (I):

wherein

R 1 =H, branched or unbranched alkyl radicals having 1 to 24 carbon atoms, substituted or unsubstituted aryl radicals having 6 to 20 carbon atoms, substituted or unsubstituted aralkyl radicals having 6 to 30 carbon atoms or substituted or unsubstituted alkaryl radicals having 6 to 30 carbon atoms and

R 2 , R 3 =branched or unbranched alkylene radicals having 1 to 24 carbon atoms, substituted or unsubstituted arylene radicals having 6 to 20 carbon atoms, substituted or unsubstituted aralkylene radicals having 6 to 30 carbon atoms or substituted or unsubstituted alkarylene radicals having 6 to 30 carbon atoms, wherein R 2 and R 3 can be identical or different,

optionally including

F) further flameproofing agents which contain no Zerewitinoff-active hydrogen atoms, in an amount of from about 0 to about 70 wt. %, based on the total amount of TPU, and

G) about 0 to about 20 wt. %, based on the total amount of TPU, of further auxiliary substances and additives,

wherein the characteristic number (formed from the ratio of equivalents, multiplied by 100, of the isocyanate groups from (A) and the sum of the Zerewitinoff-active hydrogen atoms of the compounds (B), (C) and (D)) is 85 to 120.

2. The process according to claim 1 , wherein diisocyanate A) is an aromatic diisocyanate.

3. The process according to claim 1 , wherein polyol B) is a polyether.

4. The process according to claim 1 , wherein polyol C) is selected from the group consisting of ethylene glycol, butanediol, hexanediol, 1,4-di-(beta-hydroxyethyl)-hydroquinone and 1,4-di-(beta-hydroxyethyl)bisphenol A.

5. The process according to claim 1 , wherein component D) has a functionality of on average 2.

6. In a process for the production of one of an injection-molded article and an extruded article, the improvement comprising including the thermoplastically processable polyurethane elastomer prepared according to claim 1 .