Method for producing polyol dispersions from polyurethane waste and use thereof

1. A process for producing isocyanate-reactive polyol dispersions from polyurethane waste from a post-consumer sector in the presence of polyetherols, characterized in that, in a first reaction step,

a) the polyurethane waste is firstly reacted with a reaction mixture containing at least one dicarboxylic acid or dicarboxylic acid derivative and

at least one polyetherol having an average molar mass of from 400 to 6000 g/mol and a hydroxyl functionality of from 2 to 4,

at temperatures of from 170° C. to 210° C. to form a dispersion;

and, in a second reaction step,

b) the dispersion obtained under a) is reacted again with at least one short-chain diol and/or one short-chain triol at temperatures of from 180° C. to 230° C. to give an isocyanate-reactive polyol dispersion.

2. The process for producing isocyanate-reactive polyol dispersions as claimed in claim 1 , characterized in that the at least one polyetherol has the average molar mass of from 400 to 4000 g/mol.

3. The process for producing isocyanate-reactive polyol dispersions as claimed in claim 1 , characterized in that the at least one dicarboxylic acid is selected from the group consisting of adipic acid, maleic acid, phthalic acid and succinic acid or derivatives thereof.

4. The process for producing isocyanate-reactive polyol dispersions as claimed in claim 1 , characterized in that the at least one short-chain diol and/or one short-chain triol is selected from the group consisting of ethylene glycol, diethylene glycol, 1,3-propane glycol, 1,2-butanediol, 1,4-butane glycol and glycerol.

5. The process for producing isocyanate-reactive polyol dispersions as claimed in claim 1 , characterized in that at least reaction step a) is carried out in a vessel made of stainless steel.

6. The process for producing isocyanate-reactive polyol dispersions as claimed in claim 1 , wherein the reaction mixture of step a) further comprises a free-radical former which is an inorganic or organic peroxide.

7. The process for producing isocyanate-reactive polyol dispersions as claimed in claim 1 , characterized in that, based on the total mass of the starting materials in reaction steps a) and b) together as 100% by weight, reaction step a) is carried out using

the polyurethane post-consumer waste in a total amount of from 30 to 60% by weight and/or

the at least one polyetherol in a total amount of from 20 to 45% by weight, and/or

the at least one dicarboxylic acid or the at least one dicarboxylic acid derivative in a total amount of from 5 to 25% by weight; and/or

at least one free-radical former suitable for initiating a free-radical polymerization in a total amount of from 0.1 to 5% by weight

and/or, in reaction step b),

at least one short-chain diol and/or one short-chain triol is added in a total amount of from 1.0 to 30% by weight to the dispersion obtained under a).

8. The process for producing isocyanate-reactive polyol dispersions as claimed in claim 1 , characterized in that step a) is conducted at temperatures of from 185° C. to 195° C.

9. The process for producing isocyanate-reactive polyol dispersions as claimed in claim 1 , characterized in that in step b) the dispersion obtained under a) is reacted again with at least one short-chain diol and/or one short-chain triol at temperatures from 195° C. to 230° C.

10. A method for producing a polyurethane material comprising reacting the isocyanate-reactive polyol dispersion obtained by the process according to claim 1 with an isocyanate to produce the polyurethane material.