Method for producing polyol dispersions from polyurethane waste and use thereof

Abstract

The invention relates to a method for producing isocyanate-reactive polyol dispersions from polyurethane waste as well as to the use of an isocyanate-reactive polymer dispersion obtained according to the claimed method, for producing polyurethane materials, (in particular rigid polyurethane foam materials).

Claims

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.

Description

(1) Example 1

(2) 35% by weight of a polyether triol (Dow Chemical Company, VORANOL CP 755) having an average molar mass of 700 g/mol were placed together with 15% by weight of phthalic acid, 5% by weight of maleic acid and an amount of 3% by weight of hydrogen peroxide (50% strength) in a stainless steel reactor and heated to 170° C. over a period of 120 minutes.

(3) From this temperature, 40% by weight of waste composed of polyurethane post-consumer mattresses (unsorted, shredded to a size of about 2×2×2 cm) were added in such a way that the temperature was maintained in the range from 180° C. to 190° C. until the polyurethane materials had been dispersed.

(4) The temperature was then increased to 210° C. and the mixture was stirred for two hours and, while stirring, 2% by weight of short-chain glycol (diethylene glycol) was then added in such a way that the temperature was maintained in the range from 205° C. to 220° C.

(5) The mixture was stirred for a further one hour at a temperature of 210° C. (220) and then cooled while stirring to 80° C. The recycled polyol was then pumped off, filtered through a 250 μm self-cleaning filter and cooled to room temperature.

(6) This gave a recycled polyol in which the acid number is reliably below 1.5 mg KOH/g and the content of primary aromatic amines was always below 0.05% by weight.

(7) The product had the following property profile: (specification)

(8) Hydroxyl number: 200 mg KOH/g, measured in accordance with DIN 53240

(9) Acid number: 1.0 mg KOH/g, measured in accordance with DIN 53402

(10) Viscosity: 2400 m Pa.Math.s at 25° C., measured in accordance with DIN 53019

(11) Amine number: 8 mg KOH/g, measured in accordance with DIN 53176

(12) This recycled polyol is suitable for producing rigid polyurethane foam.

(13) Example 2

(14) 35% by weight of a long-chain polyether triol (Lupranol® 3300, BASF) having an average molar mass of 420 g/mol were placed together with 14% by weight of phthalic acid, 1% by weight of maleic acid, 1% by weight of acrylic acid and an amount of 3% by weight of tert-butyl hydroperoxide (PEROXAN BHP-70-PERGAN GmbH) in a stainless steel reactor and heated to 180° C. over a period of 120 minutes.

(15) At this temperature, 40% by weight of waste composed of polyurethane post-consumer mattresses (unsorted, shredded to a size of about 2×2×2 cm) as were added in such a way that the temperature was maintained in the range from 180° C. to 190° C. until the polyurethane materials had been dispersed.

(16) The mixture was then stirred for two hours and 6% by weight of short-chain glycol (diethylene glycol) was subsequently added in such a way that the temperature was kept in the range from 205° C. to 210° C.

(17) The mixture was stirred for a further one hour at a temperature of 210° C., 2% by weight of dipropylene glycol was subsequently added and the mixture was maintained at 220° C. for a further 30 minutes and then cooled to 80° C. while stirring. The recycled polyol was then pumped off, filtered as in example 1 and cooled to room temperature.

(18) The product had the following property profile:

(19) Hydroxyl number: 265 mg KOH/g

(20) Acid number: 0.5 mg KOH/g

(21) Viscosity: 4500 m Pa.Math.s at 25° C.,

(22) Amine number: 16 mg KOH/g, in each case measured as in example 1.

(23) The acid number was further decreased by the use of a short-chain glycol (dipropylene glycol). A negative influence on the catalysis in the subsequent production of rigid polyurethane foam is thereby avoided.

(24) The process of the invention makes it possible for the first time to match, in a direct way, the properties of recycled polyols to the polyols which were used for the production of the original polyurethanes or polyurethanes used here in reprocessing. Particularly in the case of flexible polyurethanes, this has not been possible using the processes known hitherto.

(25) Example 3

(26) A number of foaming experiments for producing rigid polyurethane foam panels were carried out using recycled polyols produced according to the invention. In these foaming experiments, polyols were used in a weight ratio of rigid foam base polyol/recycled polyol (example 1 or 2) of from 90/10 to 60/40. Formulations customary for the production of rigid polyurethane foam panels were used and 7 industrial foaming tests at a foam density of from 28 kg/m.sup.3 to 60 kg/m.sup.3 were carried out.

(27) It was possible to produce rigid PUR foam panels without the properties of the PUR products produced from base polyol/recycled polyol being changed to a significant negative extent compared to corresponding original PUR products, i.e. compared to PUR products without addition of recycled polyol. The properties of the panels, e.g. compressive strength, dimensional stability and thermal conductivity, of the products was thus comparable or equally good.