EP4363476A1

EP4363476A1 - Production of pu foams using recycled polyols

Info

Publication number: EP4363476A1
Application number: EP22738450.0A
Authority: EP
Inventors: Roland Hubel; Annegret Terheiden; Felix Mühlhaus
Original assignee: Evonik Operations GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2021-07-02
Filing date: 2022-06-28
Publication date: 2024-05-08
Also published as: CA3224456A1; WO2023275031A1; CN117580885A

Abstract

The invention relates to a method of producing PU foams by reacting (a) at least one polyol component that contains recycled polyol with (b) at least one isocyanate component in the presence of (c) one or more catalysts that catalyze the reactions of isocyanate-polyol and/or isocyanate-water and/or the isocyanate trimerization reaction, (d) at least one foam stabilizer and (e) optionally one or more chemical or physical blowing agents, and the polydispersity of the respective recycled polyol is < 2, preferably < 1.5, more particularly ≤ 1.2.

Description

Production of PU foams using recycled polyols

The invention is in the field of polyurethanes and relates to the production of PU foams using recycled polyols.

Due to their excellent mechanical and physical properties, polyurethanes are used in a wide variety of areas. The area of PU foams represents a particularly important market for the most diverse types of polyurethanes.

For the purposes of this invention, polyurethanes (PU) are understood to mean all reaction products starting from isocyanates, in particular from polyisocyanates, and corresponding isocyanate-reactive molecules, in particular polyols. This also includes, inter alia, polyisocyanurates, polyureas and isocyanate or polyisocyanate reaction products containing allophanate, biuret, uretdione, uretimine or carbodiimide.

Polyurethanes are now so widespread around the world that recycling these materials is becoming increasingly important. In the prior art, therefore, there are already different recycling processes for the utilization of polyurethane waste. The well-known chemical recycling processes such as hydrolysis, e.g. described in US Pat - position can be used. These polyol mixtures are generally referred to as recycled polyols.

In principle, efforts are being made to use the recycling polyols again for the production of polyurethanes. Against this background, it was the specific object of the present invention to enable the provision of PU foams using recycled polyols without impairing the quality of the resulting foams, especially when using larger amounts of recycled polyols compared to PU foams made with conventional polyols.

Surprisingly, it has now been found that recycling polyols with a polydispersity <2, preferably <1.5, in particular <1.2, make it possible to provide PU foams of very good quality, even when large amounts of corresponding recycling polyols are used, whereas recycling -Polyols with a different polydispersity result in poorer foams and can only be used in small proportions.

The above object is achieved by the subject matter of the invention. The subject of the invention is a process for producing PU foams by reacting (a) at least one polyol component, comprising recycling polyol, (b) at least one isocyanate component in the presence of

(c) one or more catalysts which catalyze the isocyanate-polyol and/or isocyanate-water reactions and/or the isocyanate trimerization, (d) at least one foam stabilizer and

(e) optionally one or more chemical or physical blowing agents, the polydispersity of the respective recycling polyol being <2, preferably <1.5, in particular <

1.2.

The subject of the invention makes it possible to provide polyurethane foams using larger amounts of recycled polyol, which correspond to the quality of conventional polyurethane foams, but which have been produced in the same way with conventional polyols. Due to the achievable, high proportion of recycling polyol, the subject of the invention enables a significant increase in the total proportion of recycled raw materials in the polyurethane foams produced according to the invention, which is an important advance with regard to the recyclability of polyurethane foams.

The polydispersity D results from the ratio of the mass average (M ) and the number average (M _n ) of the molar mass, ie D=M /M _n . The number-average molar mass M _n , the weight-average molar mass M and the polydispersity (M / M _n ) are preferably determined in the context of the present invention by means of gel permeation chromatography (GPC), preferably based on ISO 13885-1: 2020, in particular as in described in the examples, unless explicitly stated otherwise.

The invention also makes it possible to use large amounts of the appropriate recycling polyol, with no or only an insignificant reduction in the foam quality compared with a foam made from conventionally produced polyol. It therefore corresponds to a preferred embodiment of the invention if more than 30% by weight, preferably more than 50% by weight, preferably more than 70% by weight, based on the total polyol component used, is more preferred in the process according to the invention more than 80 wt. %, in particular more than 95 wt. 2 has.

The recycling polyol used is a polyol that results in particular from the recycling of polyurethane waste. Polyurethane waste includes all those polyurethanes, especially PU foams, which are no longer used but are intended for disposal. It therefore corresponds to a preferred embodiment of the invention if the recycling polyol used is a recycling polyol produced from polyurethane waste, preferably obtained from the depolymerization of PU foam, in particular of PU hot flexible foam (PU standard foam), viscoelastic PU Foam and / or HR PU foam, wherein the recycling polyol by solvolysis, preferably by hydrolysis, aminolysis, or acidolysis Glycolysis, in particular by hydrolysis, as described, for example, in the as yet unpublished European patent applications with the file numbers 20192354.7 or 20192364.6.

Following the depolymerization process, the recycling polyol can be freed from other recycling products, such as in particular the primary aromatic amines that also occur and the reagents added for the respective depolymerization process, using conventional separation methods. Some exemplary methods for the purification and recovery of the recycling polyol from the recycling crude product mixture that is present after the respective depolymerization step are given below. One way of separating water from the raw recycle product mixture is to remove it by distillation. Primary aromatic amines such as 2,4-toluylenediamine, 2,6-toluylenediamine or isomers of methylenediphenyldiamine can be removed from the respective recycling polyol by distillation, by extraction with aromatic solvents or by washing with acidic washing water or by other methods be removed. Any solid components such as recycling catalysts, salts or remaining polyurethane components can be separated from the raw product mixture or separated from recycling polyols by filtration with various types of filters.

In particular, the recycling polyol used can be obtained from the hydrolysis of polyurethane, comprising reacting the polyurethane with water in the presence of a base-catalyst combination (I) or (II), where (I) comprises a base having a pKb value of at 25°C from 1 to 10, and a catalyst selected from the group consisting of quaternary ammonium salts containing an ammonium cation containing 6 to 30 carbon atoms and organic sulfonates containing at least 7 carbon atoms, or wherein (II) comprises a base with a pKb value at 25 ° C of <1, and a catalyst from the group of quaternary ammonium salts containing an ammonium cation with 6 to 14 carbon atoms, provided the ammonium cation does not include a benzyl radical, or containing an ammonium cation with 6 to 12 carbon atoms, provided that the ammonium cation comprises a benzyl radical. The use of recycling polyol obtained from the hydrolysis process described, which enables very simple provision of recycling polyol with a polydispersity <2, preferably <1.5, in particular <1.2, corresponds to a preferred embodiment of the invention.

Corresponding and preferred hydrolysis processes of PU materials are described, for example, in the as yet unpublished European patent applications with file numbers 20192354.7 or 20192364.6.

A particularly preferred variant, referred to here as preferred variant 1, of depolymerization by hydrolysis is described below. In particular, it is preferred if the depolymerization of the polyurethane in step a) using a base with a pKb value at 25 ° C from 1 to 10, preferably 1 to 8, more preferably 1 to 7, in particular 1, 5 to 6, and a catalyst selected from the group consisting of (i) quaternary ammonium salts containing an ammonium cation containing from 6 to 30 carbon atoms and (ii) organic sulfonate containing at least 7 carbon atoms. This corresponds to a preferred embodiment of the invention.

Preferred bases include an alkali metal cation and/or an ammonium cation. Preferred bases here are alkali metal phosphates, alkali metal hydrogen phosphates, alkali metal carbonates, alkali metal silicates, alkali metal hydrogen carbonates, alkali metal acetates, alkali metal sulfites, ammonium hydroxides or mixtures of the aforementioned. Preferred alkali metals are Na, K or Li or mixtures of the aforementioned, in particular Na or K or mixtures thereof; preferred ammonium cation is NhV.

Particularly preferred bases are K2CO3, Na2SiC>3, NH4OH, K3PO4, NH4OH or KOAc.

The base is preferably used as a saturated alkaline solution in water, the weight ratio of saturated alkaline solution to PU being in the range of preferably 0.5 to 25, preferably 0.5 to 15, more preferably 1 to 10, in particular 2 to 7.

Preferred quaternary ammonium salts have the general structure: Ri R2 R3 R4 NX with R1.R2.R3 and R4 identical or different hydrocarbon groups selected from alkyl, aryl and/or arylalkyl, where Ri to R4 are preferably selected such that the sum of the carbon atoms of the quaternary ammonium cation is 6-14, preferably 7-14, more preferably 8-13.

X is selected from halide, preferably chloride and/or bromide, bisulfate, alkyl sulfate, preferably methyl sulfate or ethyl sulfate, carbonate, bicarbonate or carboxylate, preferably acetate or hydroxide.

Very particularly preferred quaternary ammonium salts are tributylmethylammonium chloride, tetrabutylammonium hydrogen sulfate, benzyltrimethylammonium chloride, tributylmethylammonium chloride and/or trioctylmethylammonium methyl sulfate.

The organic sulfonate containing at least 7 carbon atoms which can also be used as a catalyst preferably includes alkylaryl sulfonates, alpha-olefin sulfonates, petroleum sulfonates and/or naphthalene sulfonates.

Preferred temperatures for the depolymerization are 80°C to 200°C, preferably 90°C to 180°C, more preferably 95°C to 170°C and in particular 100°C to 160°C. Preferred reaction times for the depolymerization are 1 minute to 14 hours, preferably 10 minutes to 12 hours, preferably 20 minutes to 11 hours and in particular 30 minutes to 10 hours. Preference is given to using at least 0.5% by weight of catalyst in the depolymerization, based on the weight of the polyurethane, preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight, even more preferably 1 to 8 % by weight, again more preferably 1 to 7% by weight and in particular 2 to 6% by weight.

A preferred weight ratio of base to polyurethane is in the range from 0.01 to 50, preferably from 0.1 to 25, in particular from 0.5 to 20.

This concerned the preferred variant 1 of the depolymerization.

Another particularly preferred variant, referred to here as preferred variant 2, of depolymerization by hydrolysis is described below.

If the depolymerization of the polyurethane in step a) using a base with a pKb value at 25 ° C of <1, preferably 0.5 to -2, preferably 0.25 to -1, 5, in particular 0 to -1, a catalyst from the group of quaternary ammonium salts containing an ammonium cation with 6 to 14 carbon atoms if the ammonium cation does not contain a benzyl radical, or containing an ammonium cation with 6 to 12 carbon atoms if the ammonium cation contains a benzyl radical includes, takes place, there is a further preferred embodiment of the invention.

Preferred bases here are alkali metal hydroxides, alkali metal oxides, alkaline earth metal hydroxides, alkali metal oxides or mixtures thereof. Preferred alkali metals are Na, K or Li or mixtures of the aforementioned, in particular Na or K or mixtures thereof; preferred alkaline earth metals are Be, Mg, Ca, Sr or Ba or mixtures thereof, preferably Mg or Ca or mixtures thereof. A very particularly preferred base is NaOH.

Preferred quaternary ammonium salts have the general structure: R 1 R ₂ R 3 R ₄ NX where R 1 , R 2 , R 3 and R 4 are the same or different hydrocarbyl groups selected from alkyl, aryl and arylalkyl.

X is selected from halide, preferably chloride and/or bromide, bisulfate, alkyl sulfate, preferably methyl sulfate or ethyl sulfate, carbonate, bicarbonate, carboxylate, preferably acetate or hydroxide.

Particularly preferred quaternary ammonium salts here are benzyltrimethylammonium chloride or tributylmethylammonium chloride.

Preferred temperatures for the depolymerization are 80°C to 200°C, preferably 90°C to 180°C, more preferably 95°C to 170°C and in particular 100°C to 160°C. Preferred reaction times for the depolymerization are 1 minute to 14 hours, preferably 10 minutes to 12 hours, preferably 20 minutes to 11 hours and in particular 30 minutes to 10 hours.

Preference is given to using at least 0.5% by weight of catalyst in the depolymerization, based on the weight of the polyurethane, preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight, even more preferably 1 to 8 % by weight, again more preferably 1 to 7% by weight and in particular 2 to 6% by weight. A preferred weight ratio of base to polyurethane is in the range from 0.01 to 25, preferably 0.1 to 15, preferably 0.2 to 10, in particular 0.5 to 5.

An alkaline solution is preferably used, comprising base and water, the concentration of the base preferably being greater than 5% by weight, preferably 5 to 70% by weight, preferably 5 to 60% by weight, more preferably 10 to 50% by weight %, more preferably 15 to 40%, especially 20 to 40% by weight based on the weight of the alkaline solution.

This concerned the preferred variant 2 of the depolymerization.

Furthermore, it corresponds to a preferred embodiment of the invention when the recycling polyol used was obtained from recycling, preferably by hydrolysis of polyurethane and the polydispersity of the resulting recycling polyol is at most 0.5, preferably at most 0.3, in particular at most is 0.2 higher than the polydispersity of the original polyols of the original polyurethane from which the recycling polyol is obtained.

Recycling polyols which are preferred for the purposes of the invention preferably have a functionality (groups per molecule which are reactive towards isocyanate) of 2 to 8. The number average molecular weight of the recycle polyol is preferably in the range of 500 to 15000 g/mol. The OH number of the recycling polyols is preferably from 10 to 1200 mg KOH/g. The OH number can be determined in particular on the basis of DIN 53240:1971-12.

In a preferred embodiment of the invention, recycled polyols with the above-mentioned specification for the polydispersity are used together with preferably a maximum of 50%, more preferably a maximum of 30%, particularly preferably a maximum of 20% recycled polymer polyols based on the total polyol component. Because of their proportion of high molecular weight copolymer fillers, recycling polymer polyols do not meet the requirement of polydispersity mentioned above and in claim 1. Recycled polymer polyols are available from the depolymerization of PU from polymer polyols.

Polymer polyols are known to those skilled in the art, their preparation is described in Ron Herrington, Kathy Fock Flexible Polyurethane Foams, published by Dow Chemical Company, Chapter 2, 2nd Edition, Midland, 1997. They contain up to 50% by weight of finely dispersed, solid fillers made from polyurea (PHD polyols), from polyurethanes (PIPA polyols) or from solid copolymer aggregates in which styrene-acrylonitrile copolymers are covalently linked to polyol molecules (SAN polyols).

A preferred embodiment of the invention is when the recycled polyol employed is structurally a polyether polyol, such recycled polyol preferably being obtainable from the recycling of PU waste, particularly PU foams, originally derived from conventional polyether Polyols or polyether polyols that have already been recycled once or several times were obtained. In their original form, which precedes any recycling, polyether polyols can be prepared by known processes, for example by anionic polymerization of alkylene oxides in the presence of alkali metal hydroxides, alkali metal alcoholates or amines as catalysts and with the addition of at least one starter molecule that preferably contains 2 to 8 reactive hydrogen atoms or by cationic polymerization of alkylene oxides in the presence of Lewis acids such as antimony pentachloride or boron trifluoride etherate or by polymerization of alkylene oxides via double metal cyanide catalysis. Suitable alkylene oxides contain 2 to 4 carbon atoms in the alkylene radical. Examples are tetrahydrofuran, ethylene oxide, 1,3-propylene oxide, 1,2-propylene oxide, 1,2- or 2,3-butylene oxide; ethylene oxide and 1,2-propylene oxide are preferably used. The alkylene oxides can be used individually, cumulatively, in blocks, alternately one after the other, or as mixtures. Preferred starting molecules are dihydric, trihydric or tetrahydric alcohols such as ethylene glycol, 1,2- and 1,3-propanediol, diethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, castor oil, higher polyfunctional polyols, in particular sugar compounds such as glucose, Sorbitol, mannitol and sucrose, polyvalent phenols, resols are used.

In a preferred embodiment of the invention, in particular in the production of hot flexible foams, di- or trifunctional polyether polyols can be used which have a proportion of end groups (PO end groups) resulting from propoxylation of preferably over 50%, more preferably over 80%, in particular those with a propylene oxide block or random propylene and ethylene oxide block at the chain end or those based solely on propylene oxide blocks. Such polyether polyols preferably have a functionality of 2 to 8, particularly preferably 2 to 4, number-average molecular weights in the range from 500 to 8000, preferably 800 to 5000, particularly preferably 2500 to 4500 g/mol and usually OH numbers in the range of 10 to 100, preferably 20 to 60 mg KOH/g.

According to a preferred embodiment of the invention, in particular for the production of molded and highly elastic flexible PU foams, difunctional and/or trifunctional polyether polyols with preferably at least 50%, more preferably at least 80%, primary hydroxyl groups can be used. In particular, polyether polyols with an ethylene oxide endblock -CH2-CH2-O-H can be used. Polyols for polyurethane cold foams (so-called HR polyols) can be part of this category if the average number-average molar mass simultaneously is preferably above 4000 g/mol.

In a further preferred embodiment of the invention, for the production of PU hypersoft foams, other polyether polyols which consist largely of ethylene oxide, preferably those with ethylene oxide blocks of more than 70%, more preferably of more than 90% ( Hypersoft polyols) can be used. All polyether polyols described in the context of this preferred embodiment preferably have a functionality of 2 to 8 hydroxy groups, preferably 2 to 5 hydroxy groups per molecule, preferably an average number average molecular weight of 500 to 8000 g/mol, preferably 800 to 7000 g/mol, and preferably OH numbers in the range 5 to 100 mg KOH/g, preferably 20 to 60 mg KOH /G. In the case of hot flexible foams, polyols with primary hydroxyl functions are preferably used not alone, but preferably together with polyols with secondary hydroxyl groups.

In a further preferred embodiment of the invention, particularly in the production of viscoelastic polyurethane foams, preference is given to using mixtures of different, preferably two to three, polyfunctional polyether polyols. The polyol combinations used consist preferably of a crosslinker polyol with a high functionality (>3) and a low molecular weight, preferably with an OH number of 100 to 400 mg KOH/g and/or a conventional flexible block foam polyol and/or or an HR polyol and/or a "hypersoft" polyether polyol, preferably with an OH number between 20 and 40 mg KOH/g with a high proportion of ethylene oxide and cell-opening properties. If HR polyols are used within a viscoelastic foam formulation, their proportion in the polyol mixture is preferably always less than 50%.

Irrespective of the recycling polyol according to the invention, which has a polydispersity <2, preferably <1.5, in particular <1.2, other polyols, in particular conventional polyols, can also optionally be used in the context of the present invention. Conventional polyols are polyols that do not come from recycling processes.

It therefore corresponds to a preferred embodiment of the invention if the total polyol component used comprises both recycling polyol according to the invention and one or more other polyols, the polydispersity of the one or more other polyols, if they are at least 5% by weight, preferably at least 10% by weight, particularly preferably at least 15% by weight, in particular at least 20% by weight, of the proportion of the total polyol is also <2, preferably <1.5, in particular <1.2, with the proviso that the polydispersity of the recycling polyol is at most 0.3, preferably at most 0.2, in particular at most 0.1 higher than the polydispersity of the one or more other polyols.

The process according to the invention makes it possible to provide all known types of PU foam. In a preferred embodiment of the invention, the PU foam is a PU rigid foam, a PU flexible foam, a PU hot flexible foam (standard foam), a viscoelastic PU foam, an HR PU foam, a PU hypersoft foam semi-rigid PU foam, a thermoformable PU foam or a PU integral foam, preferably a PU hot flexible foam, HR PU foam, PU hypersoft foam or viscoelastic PU foam. PU hot flexible foam is most preferred. In principle, the PU foams can be produced in the usual manner and as described in the prior art. It is well known to those skilled in the art. A basic overview can be found e.g. B. in G. Oertel, Polyurethane Handbook, 2nd Edition, Hanser/Gardner Publications Inc., Cincinnati, Ohio, 1994, pp. 177-247. Further information on the starting materials, catalysts and auxiliaries and additives that can be used can be found, for example, in the Plastics Handbook, Volume 7, Polyurethane, Carl-Hanser-Verlag Munich, 1st edition 1966, 2nd edition, 1983 and 3rd edition, 1993.

If the production of the PU foams according to the invention using f) water, g) one or more organic solvents, h) one or more stabilizers against oxidative degradation, in particular antioxidants, i) one or more flame retardants, and / or j) one or several other additives, preferably selected from the group of surfactants, biocides, dyes, pigments, fillers, antistatic additives, crosslinkers,

Chain extenders, cell openers, fragrances, cell coarseners, plasticizers, hardeners, aldehyde scavengers, additives for resistance of PU foams to hydrolysis, compatibilizers (emulsifiers), adhesion promoters, hydrophobing additives, flame lamination additives, additives for preventing cold flow, additives to reduce compression set , additives for adjusting the glass transition temperature, temperature-controlling additives and/or odor reducers, a further preferred embodiment of the invention is present.

Another object of the present invention is a composition suitable for the production of polyurethane foam, comprising at least one polyol component, at least one isocyanate component, catalyst, foam stabilizer, blowing agent, optional auxiliary, wherein the polyol component comprises recycling polyol, the polydispersity of this recycling polyol is <2, preferably <1.5, in particular <1.2. Preferred optional auxiliaries include surfactants, biocides, dyes, pigments, fillers, antistatic additives, crosslinkers, chain extenders, cell openers such as described in EP2998333A1, fragrances, cell coarsening agents such as described in EP 2986661 B1, plasticizers, hardeners, additives for preventing cold Flow as e.g. described in DE 2507161 C3, WO2017029054A1, aldehyde scavenger as e.g. described in WO2021/013607A1, additives for resistance of PU foams to hydrolysis as e.g. described in US 2015/0148438A1, compatibilizers (emulsifiers), adhesion promoters, hydrophobic laminating additives Additives such as described in EP 2292677A1, compression set-reducing additives, additives for adjusting the glass transition temperature, temperature-controlling additives and/or odor reducers.

According to a preferred embodiment of the invention, the composition according to the invention is characterized in that, based on the total polyol component, more than 30 % by weight, preferably more than 50% by weight, preferably more than 70% by weight, more preferably more than 80% by weight, in particular more than 95% by weight, recycling polyol having a polydispersity <2, preferably <1.5, in particular <1.2.

The compounds used according to the invention, their production, the use of the compounds for the production of the PU foams and the PU foams themselves are described in more detail below by way of example, without the invention being restricted to these exemplary embodiments. If ranges, general formulas or compound classes are specified below, these should not only include the corresponding ranges or groups of compounds that are explicitly mentioned, but also all sub-ranges and sub-groups of compounds that are obtained by removing individual values (ranges) or compounds can become. If documents are cited in the context of the present description, then their content, in particular with regard to the facts referred to, should fully belong to the disclosure content of the present invention. If percentages are given below, unless otherwise stated, these are percentages by weight. If mean values are given below, they are the numerical mean unless otherwise stated. If the following material properties, such. For example, if viscosities or the like are given, these are the material properties at 25 °C unless otherwise stated. If chemical (sum) formulas are used in the present invention, the indices given can represent both absolute numbers and mean values. In the case of polymeric compounds, the indices preferably represent mean values.

The method according to the invention allows access to all PU foams. Preferred PU foams for the purposes of this invention are flexible PU foams and rigid PU foams. PU flexible foams and PU rigid foams are established technical terms. The well-known and fundamental difference between flexible foams and rigid foams is that flexible foam shows elastic behavior and the deformation is therefore reversible. The hard foam, on the other hand, is permanently deformed. Various subgroups of foams that are preferred within the scope of the invention are described in more detail below, with the term “foam” being used synonymously for “foam” within the scope of this invention for the sake of simplicity.

In the context of the present invention, rigid polyurethane foam is understood in particular as meaning a foam according to DIN 7726:1982-05 which has a compressive strength according to DIN 53421:1984-06 of advantageously >20 kPa, preferably >80 kPa, preferably >100 kPa >150 kPa, particularly preferably >180 kPa. Furthermore, according to DIN EN ISO 4590:2016-12, the rigid polyurethane foam advantageously has a closed cell content of more than 50%, preferably more than 80% and particularly preferably more than 90%. PU rigid foam is mostly used for insulation purposes. PU flexible foams are elastic, reversibly deformable and mostly open-celled. This allows the air to escape easily when compressed. The generic term PU flexible foam includes in particular the following types of foam known to those skilled in the art, namely PU hot flexible foam (standard foam), PU cold foam (also highly elastic or high resilient foam), hypersoft PU foam, viscoelastic PU flexible foam and PU ester foams ( from polyester polyols). The different types of flexible PU foam are explained in more detail below and differentiated from one another.

The crucial difference between a PU hot flexible foam and a PU cold flexible foam is the different mechanical properties. The differentiation between PU hot flexible foams and PU cold flexible foams can be made in particular by the rebound elasticity, also known as "ball rebound" (BR) or "resilience". A method for determining the rebound resilience is described, for example, in DIN EN ISO 8307:2008-03. A steel ball with a specified mass is dropped onto the specimen from a certain height and the height of the rebound is then measured as a percentage of the dropping height. PU hot flexible foams have rebound values of preferably 1% to a maximum of 50%. In the case of PU cold flexible foams, the level of rebound is preferably in the range >50%. The high rebound resilience of PU cold flexible foams results from a relatively irregular cell size distribution. Another mechanical criterion is the SAG or comfort factor. Here, a foam sample is compressed in accordance with DIN EN ISO 2439:2009-05 and the ratio of the compressive stress at 65% and 25% compression is measured. PU hot flexible foams have a comfort factor of preferably < 2.5. In the case of PU cold flexible foams, the comfort factor is preferably > 2.5. In the production of PU cold flexible foams, polyether polyols which are particularly reactive towards isocyanates and have a high proportion of primary hydroxyl groups and number-average molar masses >4000 g/mol are used. On the other hand, in the case of PU hot flexible foams, predominantly less reactive polyols with secondary OH groups and a number-average molar mass of <4000 g/mol are usually used. In addition to cold block foams, cold molded foams, which are used e.g. in car seat cushions, represent a core application of PU cold foams.

Also preferred according to the invention are hypersoft PU foams, which represent a subcategory of flexible PU foams. Hypersoft PU foams have compressive stresses determined according to DIN EN ISO 3386-1:1997 + A1:2010 of preferably < 2.0 kPa and have indentation hardnesses determined according to DIN EN ISO 2439:2009-05 of preferably < 80 N. Hypersoft PU foams can be manufactured using a variety of known methods: by using a so-called hypersoft polyol in combination with so-called standard polyols and/or by using a special manufacturing method in which carbon dioxide is metered in during the foaming process. Due to a pronounced open cell structure, Hypersoft PU foams have a high level of air permeability, promote the transport of moisture in application products and help to prevent heat build-up. The Hypersoft polyols used to manufacture Hypersoft PU foams are characterized in particular by a very high proportion of primary OH groups of more than 60%.

A special class of flexible PU foams is that of viscoelastic PU foams (PU viscose foams), which are likewise preferred according to the invention. These are also known under the name of memory foam and are characterized both by a low rebound resilience according to DIN EN ISO 8307:2008-03 of preferably <15% and by a slow, gradual recovery a completed compression (recovery time preferably 2-13 s). In contrast to hot flexible PU foams and flexible cold cold foams, which have a glass transition temperature of preferably less than -32°C, the glass transition temperature for viscoelastic PU foams is preferably shifted to a range from -20 to +15°C. A pneumatic effect must be distinguished from such "structural viscoelasticity" in open-cell viscoelastic PU foams, which is essentially based on the glass transition temperature of the polymer (also known as chemical viscoelastic foams). In the latter case, the cell structure is relatively closed (low porosity). Due to the low air permeability, the air only flows back in slowly after compression, which results in slower recovery (also called pneumatic visco-foams). In many cases, both effects are combined in one visco-foam. PU visco-foams are used because of their energy - and sound-absorbing properties.

A class of PU foams that is particularly important for applications in the automotive sector and that can be classified between those of rigid and flexible foams in terms of properties consists of semi-rigid PU foams (also semi-flexible PU foams). These are also preferred according to the invention. Like most PU foam systems, semi-flexible foam systems also use the diisocyanate/water reaction and the resulting CO2 as a foaming agent. The rebound resilience is generally lower than that of classic flexible foams, especially cold foams. Semi-flexible foams are harder than conventional flexible foams. A characteristic feature of semi-flexible foams is their high number of open cells (preferably >90% of the cells). The densities of semi-flexible foams can be significantly higher than those of flexible and rigid foams.

One or more polyols which have two or more OH groups are preferably used as polyol components, the polyol component according to the invention necessarily containing recycling polyol, the polydispersity of the recycling polyol being <2, preferably <1.5, in particular <1.2 is. This has already been described above.

For the purposes of this invention, polyols which are in principle suitable as polyol components are all organic substances having a plurality of groups which are reactive toward isocyanates, preferably having two or more OH groups, and preparations thereof. The polyol component according to the invention necessarily contains recycling polyol, the polydispersity of the recycling polyol is <2, preferably <1.5, in particular <1.2. Recycled polyol has already been described above. In addition, further polyols can optionally be used.

Preferred additional polyols that can optionally be used are all of the polyether polyols and polyester polyols customarily used for the production of polyurethane systems, in particular polyurethane foams.

Polyether polyols can, for. B. be obtained by reacting polyhydric alcohols or amines with alkylene oxides. Polyester polyols are preferably based on esters of polybasic carboxylic acids with polyhydric alcohols (mostly glycols). The polybasic carboxylic acids can be either aliphatic (e.g. adipic acid) or aromatic (e.g. phthalic acid or terephthalic acid).

An important class of optionally usable polyols, which is accessible from natural oils such as palm or soybean oil, so-called "natural oil-based polyols" (NOPs), can be obtained on the basis of renewable raw materials. NOPs are of increasing interest for a more sustainable production of PU foams in view of the long-term limited availability of fossil resources, namely oil, coal and gas, and against the background of rising crude oil prices and have already been described many times in the production of polyurethane foams (WO 2005/033167 US 2006/0293400, WO 2006/094227, WO 2004/096882, US 2002/0103091, WO 2006/116456 and EP 1678232). A number of these polyols from various manufacturers are now available on the market (WO2004/020497, US2006/0229375, WO2009/058367). Depending on the basic raw material (e.g. soybean oil, palm oil or castor oil) and the subsequent processing, polyols with different properties result. A distinction can essentially be made here between two groups: a) polyols based on renewable raw materials, which are modified to such an extent that they can be used 100% for the production of polyurethanes (WO2004/020497, US2006/0229375); b) Polyols based on renewable raw materials which, due to their processing and properties, can only replace the petrochemical-based polyol to a certain extent (WO2009/058367). The production of polyurethane foams from recycled polyols of the polydispersity described according to the invention together with NOPs represents a preferred application of the invention.

A further class of polyols which can optionally be used are those which are obtained as prepolymers by reacting polyol with isocyanate in a molar ratio of 100:1 to 5:1, preferably 50:1 to 10:1.

The so-called filler polyols (polymer polyols) represent yet another class of optionally usable polyols. These are characterized in that they contain solid organic fillers up to a solids content of 40% by weight or more in disperse distribution. For example, you can use: SAN polyols: These are highly reactive polyols containing a dispersed styrene/acrylonitrile (SAN)-based copolymer. PHD Polyols: These are highly reactive polyols containing polyurea particles in a dispersed form.

PIPA Polyols: These are highly reactive polyols containing polyurethane particles in dispersed form, prepared, for example, by the in situ reaction of an isocyanate with an alkanolamine in a conventional polyol.

The proportion of solids in the optional filler polyols, which depending on the application can preferably be between 5 and 40% by weight, based on the polyol, is responsible for improved cell opening, so that the polyol can be foamed in a controlled manner, especially with TDI, and the foams do not shrink occurs. The solid thus acts as an essential process aid. Another function is to control the hardness via the solids content, since higher solids content causes the foam to be harder.

The formulations with polyols containing solids are significantly less inherently stable and therefore require physical stabilization in addition to chemical stabilization through the crosslinking reaction.

Other polyols that can optionally be used are the so-called cell opener polyols. These are polyether polyols with a high ethylene oxide content, preferably at least 40% by weight, in particular from 50 to 100% by weight, based on the alkylene oxide content.

A preferred ratio of isocyanate component to polyol component within the scope of this invention, expressed as an index, is in the range from 10 to 1000, preferably 40 to 350. This index describes the ratio of the amount of isocyanate actually used to the amount of isocyanate theoretically required, corresponding to a stoichiometric ratio of isocyanate - Groups to isocyanate-reactive groups (eg OH groups, NH groups), multiplied by 100. An index of 100 stands for a molar ratio of the reactive groups of 1 to 1. One or more isocyanates are preferably used as isocyanate components have two or more isocyanate functions. All isocyanates, in particular the known aliphatic, cycloaliphatic, araliphatic and preferably aromatic polyfunctional isocyanates, can be used as the isocyanate component in the process according to the invention. Suitable isocyanates for the purposes of this invention have two or more isocyanate functions. Suitable isocyanates for the purposes of this invention are preferably all polyfunctional organic isocyanates, such as diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HMDI) and/or isophorone diisocyanate (IPDI). The mixture of MDI and higher-condensed analogues with an average functionality of 2 to 4, known as “polymeric MDI” (“crude MDI” or polyphenylpolymethylene polyisocyanate), can also preferably be used.

Particular preference is given to using 2,4'-diphenylmethane diisocyanate and/or 2,2'-diphenylmethane diisocyanate and/or polyphenylpolymethylene polyisocyanate (crude MDI) and/or 2,4-toluene diisocyanate and/or 2,6-toluene diisocyanate or mixtures of these.

MDI prepolymers are also particularly suitable. Examples of particularly suitable isocyanates are listed, for example, in EP 1712578, EP 1161474, WO 00/58383, US 2007/0072951, EP 1678232 and WO 2005/085310, to which reference is made here in its entirety. According to a preferred embodiment of the invention, the isocyanates used, preferably diphenylmethane diisocyanate (MDI) and toluene diisocyanate (TDI), preferably consist of at least 20%, more preferably at least 40%, particularly preferably at least 60% recycled isocyanates.

In a preferred embodiment of the invention, the recycling isocyanates are produced from the reaction of aromatic amine mixtures consisting of toluenediamine (TDA) and/or methylenediphenylamine (MDA), the amine mixtures preferably being at least 20%, more preferably at least 35%, particularly preferably at least 50% were obtained from the recycling of polyurethanes, preferably polyurethane foams. Suitable catalysts which can be used in the process according to the invention for producing PU foam are preferably substances which catalyze the gel reaction (isocyanate-polyol), the blowing reaction (isocyanate-water) or the dimerization or trimerization of the isocyanate. Such are known to those skilled in the art. It corresponds to a preferred embodiment of the invention when the catalyst used is selected from

Triethylenediamine, 1,4-diazabicyclo[2.2.2]octane-2-methanol, diethanolamine, N-[2-[2-(dimethylamino)ethoxy]ethyl]-N-methyl-1,3-propanediamine, 2-[[ 2-(2-(dimethylamino)ethoxy)ethyl]methylamino]ethanol, 1,T-[(3-{bis[3-(dimethylamino)propyl]amino}propyl)imino]dipropan-2-ol, [3 -(dimethylamino)propyl]urea, 1,3-bis[3-(dimethylamino)propyl]urea and/or amine catalysts of general structure (1a) and/or structure (1b): X includes oxygen, nitrogen, hydroxyl, amines of structure (NR ^m or NR ^m R ^lv ) or urea groups (N(R ^V )C(O)N(R ^VI ) or N(R ^V ")C(O)NR ^VI ^RV ")

Y includes amines NR ^VIII R ^IX or ethers OR ^lx

R ^UI include identical or different linear or cyclic, aliphatic or aromatic hydrocarbons with 1-8 carbon atoms which are optionally functionalized with an OH group; and/or comprise hydrogen

R ^{III IX} include identical or different linear or cyclic, aliphatic or aromatic hydrocarbons with 1-8 carbon atoms which are optionally functionalized with an OH group, an NH or an NH2 group; and/or comprise hydrogen m = 0 to 4, preferably 2 or 3 n = 2 to 6, preferably 2 or 3 i = 0 to 3, preferably 0-2

R ^x includes identical or different radicals consisting of hydrogen and/or linear, branched or cyclic aliphatic or aromatic hydrocarbons with 1-18 carbon atoms, which can be substituted with 0-1 hydroxyl groups and 0-1 NH 2 groups. Z includes oxygen, ^NRx or CH2.

Another class of suitable catalysts that can preferably be used in the process according to the invention are metal compounds of the metals Sn, Bi, Zn, Al or K, especially Sn, Zn or Bi. The metal compounds can be divided into the subgroups of organometallic compounds, organometallic Classify salts, organic metal salts and inorganic metal salts, which are explained below. For the purposes of this invention, the term "organometallic or organometallic compounds" includes, in particular, the use of metal-containing compounds that have a direct carbon-metal bond, here also as organometallic compounds (eg organyl tin) or organometallic or organometallic compounds (eg organotin compounds ) designated. For the purposes of this invention, the term “organometallic or organometallic salts” includes in particular the use of organometallic or organometallic compounds with a salt character, i.e. ionic compounds in which either the anion or cation is of an organometallic nature (e.g. organotin oxides, organotin chlorides or organotin -carboxylates). In the context of this invention, the term "organic metal salts" includes in particular the use of metal-containing compounds that do not have a direct carbon-metal bond and are at the same time metal salts in which either the anion or the cation is an organic compound (e.g. tin(II )-carboxylates). In the context of this invention, the expression “inorganic metal salts” includes in particular the use of metal-containing compounds or metal salts in which neither anion nor cation is an organic compound, eg metal chlorides (eg tin(II) chloride).

Suitable organic and organometallic metal salts that can be used preferably contain alcoholate, mercaptate or carboxylate anions such as acetate, 2-ethylhexanoate, octanoate, isononanoate, decanoate, neodecanoate, ricinoleate, laurate and/or oleate, particularly preferably 2-ethylhexanoate, ricinoleate, neodecanoate or isononanoate.

Suitable metal-containing catalysts that can be used are generally preferably selected such that they have no objectionable intrinsic odor, are essentially toxicologically harmless and that the resulting polyurethane systems, in particular polyurethane foams, have the lowest possible catalyst-related emissions.

It may be preferred to combine one or more metal compounds with one or more amine catalysts of formula (1a) and/or (1b).

In the production of polyurethane foams according to the present invention, it may be preferred to exclude the use of organometallic salts such as dibutyltin dilaurate.

Suitable amounts of catalysts for the production of PU foam in the process according to the invention depend on the type of catalyst and are preferably in the range from 0.01 to 5 pphp (=parts by weight based on 100 parts by weight polyol) or 0.1 to 10 pphp for potassium salts.

Suitable water contents in the process according to the invention depend on whether or not physical blowing agents are used in addition to the water. In the case of purely water-blown foams, the values are preferably from 1 to 20 pphp; if other blowing agents are also used, the amount used is reduced to typically, for example, 0 or, for example, 0.1 to 5 pphp. To the In order to achieve high foam density, preferably neither water nor other blowing agents are used.

Suitable physical blowing agents that can optionally be used in the context of this invention are gases, for example liquefied CO2, and volatile liquids, for example hydrocarbons with 4 or 5 carbon atoms, preferably cyclo-, iso- and n-pentane, fluorocarbons, preferably HFC 245fa, HFC 134a and HFC 365mfc, but also olefinic fluorocarbons such as HHO 1233zd or HH01336mzzZ, chlorofluorocarbons, preferably HCFC 141b, oxygen-containing compounds such as methyl formate and dimethoxymethane, or chlorinated hydrocarbons, preferably dichloromethane and 1,2-dichloroethane. Furthermore, ketones (e.g. acetone) or aldehydes (e.g. methylal) are suitable as blowing agents.

In addition to or instead of water and, if appropriate, physical blowing agents, other chemical blowing agents which react with isocyanates with evolution of gas, such as formic acid, carbamates or carbonates, can also be present in the additive composition according to the invention.

The substances mentioned in the prior art can be used as foam stabilizers (also called stabilizers for short within the meaning of the invention). The compositions according to the invention can advantageously contain one or more stabilizers. These are in particular silicon compounds having carbon atoms, preferably selected from the polysiloxanes, polydimethylsiloxanes, organomodified polysiloxanes, polyether-modified polysiloxanes and polyether-polysiloxane copolymers. Preferred silicon compounds are described by formula (1c):

Formula (1 c): [R ¹ ₂ R ² SiOi/2]a [R ¹ ₃ SiOi/ ₂ ]b [R ¹ ₂ SiO 2/ ₂ ]c [R^SiO^Jd [R ³ Si0 _3ß ]e [SiO _4ß ] _f G _g with a=0 to 12, preferably 0 to 10, particularly preferably 0 to 8 b=0 to 8, preferably 0 to 6, particularly preferably 0 to 2 c=0 to 250, preferably 1 to 200, particularly preferably 1.5 to 150 d=0 to 40, preferably 0 to 30, particularly preferably 0 to 20 e=0 to 10, preferably 0 to 8, particularly preferably 0 to 6 f=0 to 5, preferably 0 to 3, particularly preferably 0 g=0 to 3, preferably 0 to 2.5, particularly preferably 0 to 2 where: a+b+c+d+e+f+g>3 a+b>2

G = independently the same or different radicals (Oiss)n SiR ¹ _m - CH 2 CHR ⁵ - R ⁴ - CR^CR^CHs

R ⁴ = independently the same or different divalent organic radicals, preferably double organic radicals of 1 to 50 carbon atoms, optionally interrupted by ether, ester or amide groups and optionally functionalized with OH groups, or (- SiR ¹ ₂ 0 -) x SiR ¹ ₂ - groups, particularly preferably the same or different divalent organic

Radicals of 2 to 30 carbon atoms, optionally interrupted by ether, ester or amide groups and optionally functionalized with OH groups, or (-SiR ¹ ₂ 0-) x SiR ¹ ₂ - groups x = 1 to 50, preferably 1 bis 25, more preferably 1 to 10

R ⁵ = independently the same or different alkyl radicals consisting of 1 to 16 carbon atoms, aryl radicals having 6 to 16 carbon atoms or hydrogen, preferably from the

Group of alkyl radicals with 1 to 6 carbon atoms or aryl radicals with 6 to 10 carbon atoms or hydrogen, particularly preferably methyl or hydrogen where: n = 1 or 2 m = 1 or 2 n + m = 3

R ¹ = identical or different radicals selected from the group of saturated or unsaturated alkyl radicals having 1 to 16 carbon atoms or aryl radicals having 6 to 16 carbon atoms or hydrogen or -OR ⁶ , preferably methyl, ethyl, octyl, dodecyl, phenyl or hydrogen, particularly preferred methyl or phenyl.

R ² = independently identical or different polyethers obtainable by the polymerization of ethylene oxide and/or propylene oxide and/or other alkylene oxides such as butylene oxide or styrene oxide with the general formula (2) or an organic radical corresponding to the formula (3) (2) - (R ⁷ ) _h - O - [C ₂ H ₄ 0]i - [C ₃ H ₆ 0]j - [CR ⁸ ₂ CR ⁸ 20]k - R ⁹

(3) - Oh- R ¹⁰ where h = 0 or 1

R ⁷ = divalent organic radical, preferably divalent organic alkyl or aryl radical optionally substituted with -OR ⁶ , more preferably a divalent organic radical of the type C _P H2 . i = 0 to 150, preferably 1 to 100, particularly preferably 1 to 80 j = 0 to 150, preferably 0 to 100, particularly preferably 0 to 80 k = 0 to 80, preferably 0 to 40, particularly preferably 0 p = 1 - 18, preferably 1 - 10, more preferably 3 or 4 where i + j + k > 3

R ³ = identical or different radicals selected from the group of saturated or unsaturated alkyl radicals potentially substituted with heteroatoms, preferably identical or different radicals selected from the group of saturated or unsaturated alkyl radicals with 1 to 16 Carbon atoms or aryl radicals of 6-16 carbon atoms potentially substituted with halogen atoms, most preferably methyl, vinyl, chloropropyl or phenyl.

R ⁶ = identical or different radicals selected from the group of saturated or unsaturated alkyl radicals having 1 to 16 carbon atoms or aryl radicals having 6 to 16 carbon atoms or hydrogen, preferably saturated or unsaturated alkyl radicals having 1 to 8 carbon atoms or hydrogen, methyl, ethyl being particularly preferred , isopropyl or hydrogen.

R ⁸ = identical or different radicals selected from the group of alkyl radicals with 1 to 18 carbon atoms, potentially substituted with ether functions and potentially substituted with heteroatoms such as halogen atoms, aryl radicals with 6 - 18 carbon atoms, potentially substituted with ether functions, or hydrogen, preferably alkyl radicals with 1 to 12 carbon atoms potentially substituted with ether functions and potentially substituted with heteroatoms such as halogen atoms or aryl radicals having 6 to 12 carbon atoms potentially substituted with ether functions, or hydrogen, more preferably methyl, ethyl, benzyl or hydrogen.

R ⁹ = same or different radicals selected from the group hydrogen, alkyl, -C(0)-R ¹¹ , -C(0)0-R ¹¹ or -C(0)NHR ¹¹ , saturated or unsaturated, optionally substituted with Heteroatoms, preferably hydrogen or alkyl radicals having 1 to 8 carbon atoms or acetyl, particularly preferably hydrogen, acetyl, methyl or butyl.

R ¹⁰ = identical or different radicals selected from the group of saturated or unsaturated alkyl radicals or aryl radicals, potentially substituted with one or more OH,

Ether, epoxide, ester, amine and/or halogen substituents, preferably saturated or unsaturated alkyl radicals with 1 to 18 carbon atoms or aryl radicals with 6 - 18 carbon atoms, optionally substituted with one or more OH, ether, epoxide, ester, amine and/or Halogen substituents, particularly preferably saturated or unsaturated alkyl radicals having 1 to 18 carbon atoms or aryl radicals having 6 - 18 carbon atoms substituted with at least one OH, ether, epoxide, ester, amine and/or halogen substituent.

R ¹¹ = identical or different radicals selected from the group of alkyl radicals having 1 to 16 carbon atoms or aryl radicals having 6 - 16 carbon atoms, preferably saturated or unsaturated alkyl radicals having 1 - 8 carbon atoms or aryl radicals having 6 - 12 carbon atoms, particularly preferably methyl, ethyl, butyl or phenyl.

The foam stabilizers of the formula (1c) can be used in PU systems, preferably mixed in organic solvents such as, for example, dipropylene glycol, polyether alcohols or polyether diols.

In the case of mixtures of stabilizers of the formula (1c), a compatibilizer can preferably also be used. This can be selected from the group of aliphatic or aromatic hydrocarbons, particularly preferably aliphatic polyethers or polyesters.

The substances mentioned in the prior art can preferably be used as silicon compounds having one or more carbon atoms. Preferably such Si compounds used, which are particularly suitable for the respective foam types. Suitable siloxanes are described, for example, in the following documents: EP 0839852, EP 1544235, DE 102004001408, WO 2005/118668, US 2007/0072951, DE 2533074, EP 1537159 EP 533202, US 3933695, EP 0724239, DE 0724239, DE 429044 867465. The Si compounds can be produced as described in the prior art. Suitable examples are e.g. e.g. in US 4147847, EP 0493836 and US 4855379.

Preferably, from 0.00001 to 20 parts by mass of foam stabilizers, in particular silicon compounds, can be used per 100 parts by mass of polyol components.

All substances known from the prior art which are used in the production of polyurethanes, in particular polyurethane foams, can be used as further optional additives, such as blowing agents, preferably water to form CO2 and, if necessary, other physical blowing agents Flame retardants, buffer substances, surfactants, biocides, dyes, pigments, fillers, antistatic additives, crosslinkers, chain extenders, cell openers such as described in EP2998333A1, nucleating agents, thickeners, fragrances, cell coarsening agents such as described in EP 2986661 B1, plasticizers, hardeners, additives for the prevention of cold flow as described, for example, in DE 2507161C3, WO2017029054A1, aldehyde scavengers, as described, for example, in WO2021/013607A1, additives for the resistance of PU foams to hydrolysis, as described, for example, in US 2015/0148438A1, compatibilizers (emulsifiers), adhesion promoters, hydrophobing agents additive e, flame lamination additives as described, for example, in E 2292677B1, compression set-reducing additives, additives for adjusting the glass transition temperature, temperature-controlling additives, odor reducers and/or additional catalytically active substances, in particular as defined above.

Crosslinkers that can be used as an option and chain extenders that can be used as an option are low molecular weight, polyfunctional compounds that are reactive toward isocyanates. For example, hydroxyl- or amine-terminated substances such as glycerol, neopentyl glycol, dipropylene glycol, sugar compounds, 2-methyl-1,3-propanediol, triethanolamine (TEOA), diethanolamine (DEOA) and trimethylolpropane are suitable. Crosslinkers that can also be used are polyethoxylated and/or polypropoxylated glycerol or sugar compounds whose number-average molecular weight is below 1500 g/mol. The optional use concentration is preferably between 0.1 and 5 parts, based on 100 parts of polyol, but can also deviate from this depending on the formulation. When using crude MDI for foam molding, this also takes on a crosslinking function. The content of low-molecular crosslinkers can therefore be correspondingly reduced as the amount of crude MDI increases. Suitable optional stabilizers against oxidative degradation, so-called antioxidants, are preferably all common free-radical scavengers, peroxide scavengers, UV absorbers, light stabilizers, complexing agents for metal ion impurities (metal deactivators). Compounds of the following substance classes or substance classes containing the following functional groups can preferably be used: 2-(2'-hydroxyphenyl)benzotriazoles, 2-hydroxybenzophenones, benzoic acids and benzoates, phenols, in particular containing tert-butyl and/or methyl substituents on the aromatic compound, benzofuranones, diarylamines , triazines, 2,2,6,6-tetramethylpiperidines, hydroxylamines, alkyl and aryl phosphites, sulfides, zinc carboxylates, diketones.

Suitable optional flame retardants for the purposes of this invention are all substances which are considered suitable according to the prior art. Preferred flame retardants are, for example, liquid organic phosphorus compounds, such as halogen-free organic phosphates, e.g. triethyl phosphate (TEP), halogenated phosphates, e.g. tris(1-chloro-2-propyl) phosphate (TCPP), tris(1,3-dichloroisopropyl) phosphate ( TDCPP) and tris(2-chloroethyl) phosphate (TCEP) and organic phosphonates, e.g. dimethyl methane phosphonate (DMMP), dimethyl propane phosphonate (DMPP), or oligomers ethyl ethylene phosphates or solids such as ammonium polyphosphate (APP) and red phosphorus. Halogenated compounds, for example halogenated polyols, and solids such as expandable graphite and melamine are also suitable as flame retardants.

The process according to the invention makes it possible to produce polyurethane foams with particularly high proportions of recycling polyols. For the purposes of the invention, the term polyurethane is to be understood in particular as a generic term for a polymer made from di- or polyisocyanates and polyols or other species that are reactive towards isocyanate, such as amines, for example, where the urethane bond does not have to be the exclusive or predominant type of bond. Polyisocyanurates and polyureas are also expressly included.

The production of polyurethane foams according to the invention can be carried out by any method familiar to the person skilled in the art, for example by hand mixing or preferably with the aid of high-pressure or low-pressure foaming machines. The process according to the invention can be carried out continuously or batchwise. A discontinuous implementation of the method is preferred in the production of molded foams, refrigerators, shoe soles or panels. A continuous procedure is preferred in the production of insulating panels, metal composite elements, blocks or spray processes.

Another object of the present invention is a polyurethane foam, preferably PU rigid foam, PU flexible foam, PU hot flexible foam (standard foam), viscoelastic PU foam, HR PU foam, PU hypersoft foam, semi-rigid PU foam, thermoformable PU foam or PU integral foam, preferably PU hot flexible foam, HR PU foam, PU Hypersoft foam or viscoelastic PU foam, most preferably hot flexible PU foam, produced according to a method according to the invention as described above.

A very particularly preferred flexible polyurethane foam for the purposes of this invention has the following composition in particular:

Component parts by weight (pphp)

Polyol comprising Recycled Polyol 100

(amine) catalyst 0.01 to 5

Tin catalyst 0 to 5, preferably 0.001 to 2

Siloxane 0.1 to 15, preferably 0.2 to 7

Water 0 to <15, preferably 0.1 to 10

Other blowing agents 0 to 130 Flame retardants 0 to 70 Fillers 0 to 150 Other additives 0 to 20 Isocyanate index: greater than 50

The polyurethane foams according to the invention can, for. B. as refrigerator insulation, insulating board, sandwich element, pipe insulation, spray foam, 1 & 1.5 component can foam (a 1.5 component can foam is a foam that is produced by destroying a container in the can), imitation wood, model foam , packaging foam, mattress, furniture pad, automotive seat pad, headrest, instrument panel, automotive interior trim, automotive headliner, sound absorbing material, steering wheel, shoe sole, carpet backing foam, filter foam, sealing foam, sealant, adhesive, binder, paint or as a coating or to manufacture related products be used. This corresponds to a further object of the invention.

The present invention is described by way of example in the examples listed below, without the invention, the scope of which results from the entire description and the claims, being restricted to the embodiments mentioned in the examples. Examples:

Production of PU flexible foams

The following formulation was used to produce hot flexible foam for testing the recycling polyols with regard to their foaming properties and their influence on the physical foam properties. In this context, for example, 1.0 part (1.0 pphp) of a component means 1 g of this substance per 100 g of polyol.

Table 1: Formulation for the production of PU hot-cure flexible foams. Formulation 1 Parts by mass (pphp) Polyol ¹⁾ 100 pphp

Water 4.00 pphp

KOSMOS® T9 ²⁾ 0.20 pphp DABCO ^® DMEA ³⁾ 0.15 pphp TEGOSTAB ^® BF2370 ⁴⁾ 1.0 pphp Desmodur ^® T 80 ⁵⁾ Variable, constant index of 105

¹⁾ Polyol: standard polyether polyol Arcol® 1104 available from Covestro, this is a glycerol-based polyether polyol with an OH number of 56 mg KOH/g and a number-average molar mass of 3000 g/mol or recycling according to the invention Polyols or recycled polyol not according to the invention. The recycled polyols are processed via a chemical

Recycling process of PU hot flexible foams. The respective recycling processes for preparing the recycling polyols according to the invention and those not according to the invention are described in the following section.

²⁾ KOSMOS® T9, available from Evonik Industries: tin(II) salt of 2-ethylhexanoic acid. ³⁾ DABCO® DMEA: dimethylethanolamine, available from Evonik Industries. amine

Catalyst for the production of polyurethane foams

⁴⁾ Polyether modified polysiloxane available from Evonik Industries.

⁵⁾ Toluene diisocyanate T 80 (80% 2,4-isomer, 20% 2,6-isomer) from Covestro, 3 mPa·s, 48% NCO, functionality 2.

GPC measurements to determine the polydispersity of polyols

The polydispersity and the average molecular masses M _n and M of the recycling polyols were determined using gel permeation chromatography based on ISO 13885-1:2020 under the following conditions: Separation column combination SDV 1000/10000 Ä with pre-column (length 65 cm, column temperature 30 °C) THF as mobile phase, flow rate 1 ml/min, sample concentration 10 g/l, injection volume 20 ml, refractive index detector engl. Rl detector) at 30 °C, calibration with polystyrene (162 - 2520000 g/mol). The values obtained are polystyrene mass equivalents.

Production of recycling polyols

Recvclinq-Polvol 1 (non-inventive)

The non-inventive recycling polyol 1 was produced in accordance with a regulation from H&S Anlagentechnik from 2012: https://www.dbu.de/OPAC/ab/DBU- Final Report-AZ-29395.pdf A reactor from the Parr company ( Parr Instrumental Company) equipped with a glass inner container and a mechanical stirrer was filled with 300.2 g of compressed PU foam pieces (approx. 1 cm x 1 cm). The polyurethane foam used was prepared according to Formulation 1, in which the conventional polyol Arcol® 1104 is used. Then 152.64 g of Arcol® 1104 polyol, 75.63 g of phthalic acid and 11.97 g of aqueous hydrogen peroxide solution (30% by weight in water) were added to the foam pieces. The reaction mixture was heated to 250°C and maintained within a temperature range of 237°C and 256°C for five hours. After the reaction time had elapsed, the heating was switched off, and when a reaction temperature of 160° C. had been reached, a second portion of 140.63 g of Arcol® 1104 was added under a countercurrent of nitrogen. The liquid reaction mixture was cooled to room temperature and, after decanting, used as recycle polyol 1 with a polydispersity of 4.38. The recycling process was used repeatedly to provide a large enough amount of recycled polyol for the foaming experiments.

Recvclinq-Polvol 2 (according to the invention)

The recycling polyol 2 according to the invention was obtained by the hydrolysis of polyurethane in the presence of a saturated K ₂ CO 3 solution and tetrabutylammonium hydrogen sulfate as a catalyst:

A Parr reactor (Parr Instrumental Company) equipped with a PTFE inner vessel and a mechanical stirrer was charged with 25 g of compressed foam pieces (ca. 1 cm×1 cm). The polyurethane foam used was prepared according to Formulation 1 in which the conventional polyol Arcol® 1104 was used. Then 75 g of saturated K ₂ CO 3 solution (pKb value 3.67 at 25°C) were added. The catalyst tetrabutylammonium hydrogen sulfate was then added at 5% by weight, based on the mass of the reaction mixture. The reactor was sealed and the reaction mixture was heated to an internal temperature of 150°C for 14 hours. Upon completion of the 14 hours, heating was discontinued and the reaction mixture was cooled to room temperature. After opening the reactor, the reaction mixture was transferred to a round bottom flask. The water was removed via rotary evaporation and the remaining reaction mixture was washed with cyclohexane extracted. The cycle hexane solution was washed with 1N aqueous HCl solution and then dried over magnesium sulfate. After removal of the cycle hexane via Rctaticnsevaporation, the recycling Pclycl 2 was obtained with a Pclydispersity of 1.07 in the form of a liquid. The hydrolysis process was repeated to provide a sufficient amount of recycled plastic for the foaming experiments.

Recvclinq-Polvol 3 (according to the invention)

The recycling Pclycl 3 according to the invention was obtained by the hydrolysis of polyurethane in the presence of a 20% sodium hydroxide solution and tributylmethylammonium chloride as a catalyst:

A Parr reactor (Parr Instrumental Company) equipped with a PTFE inner vessel and a mechanical stirrer was charged with 25 g of compressed foam pieces (ca. 1 cm×1 cm). The polyurethane foam used was prepared according to Formulation 1 in which the conventional polyol Arcol® 1104 was used. Then 75 g of sodium hydroxide solution (20% by weight in water) were added.

The catalyst tributylmethylammonium chloride was then added at 2.5% by weight based on the mass of the reaction mixture. The reactor was sealed and the reaction mixture was heated to an internal temperature of 130°C for 14 hours. Upon completion of the 14 hours, heating was discontinued and the reaction mixture was cooled to room temperature. After opening the reactor, the reaction mixture was transferred to a round bottom flask. The water was removed via rotary evaporation and the remaining reaction mixture was extracted with cyclohexane. The cyclohexane phase was washed with 1N aqueous HCl solution and then dried over magnesium sulfate. After the cyclohexane had been removed by rotary evaporation, the recycling polyol 3 with a polydispersity of 1.06 was obtained in the form of a liquid and used for foaming experiments. The hydrolysis process was repeated to provide a sufficient amount of recycled polyol for the foaming experiments.

General procedure for the production of PU hot flexible foams

The polyurethane foams were produced in the laboratory as so-called hand foams. The foams were produced according to the following information at 22° C. and 762 mm Hg air pressure. To produce the polyurethane foams according to formulation I, either 300 or 400 g of polyol were used in each case. The other formulation components were converted accordingly. For example, 1.0 part (1.0 pphp) of a component meant 1 g of this substance per 100 g of polyol.

For the foams according to formulation I, the tin catalyst tin(II) 2-ethylhexanoate, polyol, the water, the amine catalysts and the respective foam stabilizer were placed in a paper cup and mixed for 60 s with a disc stirrer at 1000 rpm. After the first stir the isocyanate was added and incorporated with the same stirrer for 7 s at 2500 rpm and immediately transferred to a paper-lined box (30 cm×30 cm base and 30 cm height). After pouring, the foam rose in the foaming box. Ideally, the foam blew off when the maximum rise height was reached and then sagged back slightly. The cell membranes of the foam bubbles opened up and an open-pored cell structure of the foam was obtained.

The characteristic parameters described in the following section were determined to assess the properties.

Application tests

The foams produced were evaluated on the basis of the following physical properties: a) Sagging of the foam after the end of the rise phase (=fall back).

The relapse or subsequent ascent results from the difference in foam height after direct blowing off and after 3 minutes after blowing off the foam. The foam height is measured using a needle attached to a centimeter ruler at the maximum in the center of the foam dome. A positive value describes the sagging of the foam after blowing off, a negative value describes the subsequent rise of the foam. b) Foam height is the height of the free-rising foam formed after 3 minutes. Foam height is reported in centimeters (cm). c) rise time

The time between the end of mixing the reaction components and the blowing off of the polyurethane foam. The rise time is given in seconds (s). d) porosity

The air permeability of the foam was determined based on DIN EN ISO 4638:1993-07 by measuring the dynamic pressure on the foam. The back pressure measured was given in mm of water column, with the lower back pressure values then characterizing the more open foam. The values were measured in the range from 0 to 300 mm water column. The dynamic pressure was measured using an apparatus comprising a nitrogen source, reducing valve with manometer, flow control screw, washing bottle, flow meter, T-piece, support nozzle and a scaled glass tube filled with water. The support nozzle has an edge length of 100×100 mm, a weight of 800 g, a clear width of the outlet opening of 5 mm, a clear width of the lower support ring of 20 mm and an outer diameter of the lower support ring of 30 mm.

The measurement is carried out by setting the nitrogen pre-pressure to 1 bar using the reducing valve and adjusting the flow rate to 480 l/h. The amount of water is set in the graduated glass tube in such a way that no pressure difference can be built up and read. For the measurement of the test specimen with dimensions of 250 x 250 x 50 mm, the contact nozzle is placed on the corners of the test specimen edges congruently and once on the (estimated) center of the test specimen (each on the side with the largest surface). is read when a constant dynamic pressure has been established. The evaluation is carried out by averaging over the five measured values obtained. d) Number of cells per cm (cell number): This is determined optically on a cut surface (measured according to DIN EN 15702:2009-04). f) Compression hardness CLD 40% according to DIN EN ISO 3386-1:1997 + A1:2010. The measured values are given in kilopascals (kPa). g) compression set

Five specimens each measuring 5 cm×5 cm×2.5 cm were cut out of the finished foams. The initial thickness was measured. The compression set was measured at the earliest 72 hours after manufacture in accordance with DIN EN ISO

1856:2018-11. The specimens were placed between the plates of the former and were compressed to 90% of their thickness (i.e. to 2.5mm). Within 15 minutes the specimens were placed in an oven at 70°C and left there for 22 hours. After this time, the device was removed from the oven, the specimens were removed from the device within 1 minute and placed on a wooden surface. After 30 minutes relaxation, the thickness was measured again and the compression set calculated. The results are given in percent according to the following formula: DVR=(d0-dr)/d0 x 100% h) Tensile strength and elongation at break according to DIN EN ISO 1798:2008-04. The measured values for tensile strength are given in kilopascals (kPa), for elongation at break in percent (%). i) Resilience according to DIN EN ISO 8307:2008-03. The measurement values are given in percent (%).

Results of the foaming The recycling polyols 2 and 3 according to the invention and the recycling polyol 1 not according to the invention are tested in formulation I, Table 1 in comparison with the conventional polyol Arcol®1104. The results of the performance tests for the use of the various polyols are given in Tables 2 and 3. Table 2: Foaming results for the PU hot flexible foams, produced according to Formulation 1, Table 1 using the recycling polyols 1 and 2 and the conventional polyol Arcol®1104. 400 g of polyol were used in each case. The other formulation components were converted accordingly *collapse or collapsed foams are taken to mean those that collapse during foam formation.

The results in Table 2 show that when using 100 pphp of Recycled Polyol 2 of the invention, the foam during manufacture exhibits comparable foaming behavior as when using 100 pphp of Arcol® 1104. Likewise, the foam physical properties of Foam #3 made from 100 pphp recycled polyol 2 is comparable to reference foam #1 based on 100 pphp Arcol® 1104 in terms of porosity, cell count, resilience and compression set. Improved values are even measured for the physical properties elongation at break and tensile strength compared to reference foam #1. Only the compression hardness shows a slightly reduced value for foam #3 with recycling polyol 2. In contrast, no standard foam could be obtained when using 100 pphp of the recycling polyol 1 not according to the invention. Foam #2 collapsed completely. Only using a reduced amount of 30 pphp of Recycled Polyol 1 in combination with 70 pphp of conventional polyol Arcol® 1104 was an evaluable foam obtained (Foam #5). But even at a reduced usage level of 30 pphp of Recycled Polyol 2, foam physical properties for porosity, compression set, elongation at break, tensile strength, Rebound resilience and compression set worse compared to reference foam #1 and foam #3 according to the invention 300 g polyol used. The other formulation components were converted accordingly.

The results in Table 3 show that when using 100 pphp of Recycled Polyol 3 of the invention, the foam during manufacture had a comparable Same foaming behavior as when using 100 pphp Arcol® 1104. Likewise, the physical foam properties of Foam #8 made from 100 pphp Recycled Polyol 3 are comparable to Reference Foam #6 in terms of porosity, cell count, elongation at break, tensile strength, resilience and compression set to 100 pphp Arcol® 1104. Compression Hardness shows a slightly increased value for Foam #8 with Recycled Polyol 3. In contrast, no standard foam could be obtained when using 100 pphp of the recycling polyol 1 not according to the invention. Foam #7 collapsed completely.

Claims

Expectations:

1. A process for producing polyurethane foams by reacting (a) at least one polyol component, comprising recycled polyol,

(b) at least one isocyanate component in the presence of

(e) optionally one or more chemical or physical blowing agents, characterized in that the polydispersity of the respective recycling polyol is <2, preferably <1.5, in particular <1.2.

2. The method according to claim 1, characterized in that the polyol component comprises both recycling polyol and one or more other polyols, the polydispersity of the one or more other polyols, if they are at least 5% by weight, preferably at least 10 % by weight, particularly preferably at least 15% by weight, in particular at least 20% by weight, of the proportion of the total polyol is also <2, preferably <1.5, in particular <1.2, with the proviso that that the polydispersity of the recycling polyol is at most 0.3, preferably at most 0.2, in particular at most 0.1 higher than the polydispersity of the one or more other polyols.

3. The method according to claim 1 or 2, characterized in that the polyurethane

Foam a PU rigid foam, a PU flexible foam, a PU hot flexible foam, a viscoelastic PU foam, a HR PU foam, a PU hypersoft foam, a semi-rigid PU foam, a thermoformable PU foam or a PU integral foam, preferably a PU hot flexible foam, HR PU foam, PU hypersoft foam or viscoelastic PU foam, most preferably a PU hot flexible foam.

4. The method according to any one of claims 1 to 3, characterized in that the reaction is carried out using f) water, g) one or more organic solvents, h) one or more stabilizers against oxidative degradation, in particular antioxidants, i) one or several flame retardants, and/or j) one or more other additives.

5. The method according to any one of claims 1 to 4, characterized in that the foam stabilizer is selected from the group of silicon compounds having carbon atoms, which are preferably described by the formula (1c), or mixtures of several of these compounds:

Formula (1 c): [R ¹ ₂ R ² SiOi/2]a [R ¹ ₃ SiOi/ ₂ ]b [R^SiO^c [R^SiO^d [R ³ Si0 _3ß ]e [Si0 _4ß ] _f G _g with a = 0 to 12, preferably 0 to 10, particularly preferably 0 to 8 b = 0 to 8, preferably 0 to 6, particularly preferably 0 to 2 c = 0 to 250, preferably 1 to 200, particularly preferably 1, 5 to 150 d=0 to 40, preferably 0 to 30, particularly preferably 0 to 20 e=0 to 10, preferably 0 to 8, particularly preferably 0 to 6 f=0 to 5, preferably 0 to 3, particularly preferably 0 g = 0 to 3, preferably 0 to 2.5, particularly preferably 0 to 2 where: a+b+c+d+e+f+g>3 a+b>2

G = independently the same or different radicals

R ⁴ = independently the same or different divalent organic radicals, preferably double organic radicals of 1 to 50 carbon atoms, optionally interrupted by ether, ester or amide groups and optionally functionalized with OH groups, or (- SiR ¹ ₂ 0 -)xSiRV groups, particularly preferably the same or different divalent organic radicals of 2 to 30 carbon atoms, optionally interrupted by ether, ester or amide groups and optionally functionalized with OH groups, or (-SiR ¹ ₂ 0-)xSiRV Groups x = 1 to 50, preferably 1 to 25, particularly preferably 1 to 10

R ⁵ = independently the same or different alkyl radicals consisting of 1 to 16 carbon atoms, aryl radicals having 6 to 16 carbon atoms or hydrogen, preferably from the group of alkyl radicals having 1 to 6 carbon atoms or aryl radicals having 6 to 10 carbon atoms or hydrogen, particularly preferably methyl or hydrogen where: n = 1 or 2 m = 1 or 2 n + m = 3

R ¹ = identical or different radicals selected from the group of saturated or unsaturated alkyl radicals having 1 to 16 carbon atoms or aryl radicals having 6 to 16 carbon atoms or hydrogen or -OR ⁶ , preferably methyl, ethyl, octyl, dodecyl, phenyl or hydrogen, particularly preferred methyl or phenyl. R ² = independently identical or different polyethers obtainable by the polymerization of ethylene oxide and/or propylene oxide and/or other alkylene oxides such as butylene oxide or styrene oxide with the general formula (2) or an organic radical corresponding to the formula (3) where h = 0 or 1

R ⁷ = divalent organic radical, preferably divalent organic alkyl or aryl radical optionally substituted with -OR ⁶ , more preferably a divalent organic radical of the type C _P H _2p . i = 0 to 150, preferably 1 to 100, particularly preferably 1 to 80 j = 0 to 150, preferably 0 to 100, particularly preferably 0 to 80 k = 0 to 80, preferably 0 to 40, particularly preferably 0 p = 1 - 18, preferably 1 - 10, more preferably 3 or 4 where i + j + k > 3

R ³ = identical or different radicals selected from the group of saturated or unsaturated alkyl radicals potentially substituted with heteroatoms, preferably identical or different radicals selected from the group of saturated or unsaturated alkyl radicals having 1 to 16 carbon atoms or aryl radicals having 6 - 16 carbon atoms potentially substituted with Halogen atoms, particularly preferably methyl, vinyl, chloropropyl or phenyl.

Ether, epoxide, ester, amine and/or halogen substituents, preferably saturated or unsaturated Alkyl radicals having 1 to 18 carbon atoms or aryl radicals having 6-18 carbon atoms optionally substituted with one or more OH, ether, epoxide, ester, amine and/or halogen substituents, more preferably saturated or unsaturated alkyl radicals having 1 to 18 carbon atoms or aryl radicals 6 - 18 carbon atoms substituted with at least one OH, ether, epoxide, ester, amine and/or halogen substituent.

6. The method according to any one of claims 1 to 5, characterized in that the catalyst for the production of PU foam is selected from

Triethylenediamine, 1,4-diazabicyclo[2.2.2]octane-2-methanol, diethanolamine, N-[2-[2-(dimethylamino)ethoxy]ethyl]-N-methyl-1,3-propanediamine, 2-[[ 2-(2-(dimethylamino)ethoxy)ethyl]methylamino]ethanol, 1,1'-[(3-{bis[3-(dimethylamino)propyl]amino}propyl)imino]dipropan-2-ol, [3 -(dimethylamino)propyl]urea, 1,3-bis[3-(dimethylamino)propyl]urea and/or amine catalysts of the general structure (1a) and/or the structure (1b):

X includes oxygen, nitrogen, hydroxyl, amines of structure (NR ^m or NR ^m R ^lv ) or urea groups (N(R ^V )C(O)N(R ^VI ) or N(R ^V ")C(O)NR ^VI ^RV ")

Y includes amines NR ^VIII R ^IX or ethers OR ^lx

R ^{III IX} include identical or different linear or cyclic, aliphatic or aromatic hydrocarbons with 1-8 carbon atoms which are optionally functionalized with an OH group, an NH or an NH2 group; and/or comprise hydrogen m = 0 to 4, preferably 2 or 3 n = 2 to 6, preferably 2 or 3 i = 0 to 3, preferably 0 to 2

R ^x includes identical or different radicals consisting of hydrogen and/or linear, branched or cyclic aliphatic or aromatic hydrocarbons with 1-18 carbon atoms, which can be substituted with 0-1 hydroxyl groups and 0-1 NH 2 groups. Z includes oxygen, ^NRx or CH2. and or

Metal compounds including organometallic metal salts, organic metal salts, inorganic metal salts and organometallic compounds of the metals Sn, Bi, Zn, Al or K, preferably Sn or Bi, or mixtures thereof.

7. The method according to any one of claims 1 to 6, characterized in that, based on the total polyol component used, more than 30% by weight, preferably more than 50% by weight, preferably more than 70% by weight, more preferably more than 80% by weight, in particular more than 95% by weight, recycling polyol having a polydispersity <2, preferably <1.5, in particular <1.2, is used.

8. The method according to any one of claims 1 to 7, characterized in that the recycling polyol used is a recycling polyol produced from polyurethane waste, preferably obtained from the depolymerization of PU foam, in particular PU flexible foam, PU standard foam , Viscoelastic PU foam and/or HR-PU foam, the recycling polyol and/or recycling polymer being obtained by solvolysis, preferably by glycolysis, hydrolysis, acidolysis or aminolysis, in particular by hydrolysis.

9. The method according to any one of claims 1 to 8, characterized in that the recycling polyol used was obtained from the hydrolysis of polyurethane, comprising reacting the polyurethane with water in the presence of a base-catalyst combination (I) or (II) , wherein (I) comprises a base having a pKb value at 25 °C from 1 to 10, and a catalyst which is selected from the group consisting of quaternary ammonium salts containing an ammonium cation comprising 6 to 30 carbon atoms and organic sulfonates containing at least 7 carbon atoms is selected, or where (II) comprises a base with a pKb value at 25 ° C of <1, and a catalyst from the group of quaternary ammonium salts containing an ammonium cation having 6 to 14 carbon atoms, provided the ammonium -Cation does not include a benzyl radical, or else containing an ammonium cation with 6 to 12 carbon atoms, provided that the ammonium cation comprises a benzyl radical.

10. The method according to any one of claims 1 to 9, characterized in that the recycling polyol used was obtained from the recycling, preferably by hydrolysis, of polyurethane, the polydispersity of the recycling polyol being at most 0.5, preferably at most 0 3, in particular a maximum of 0.2 is higher than the polydispersity of the original polyols of the recycled polyurethane from which the recycling polyol is obtained.

11. A composition suitable for producing polyurethane foam, comprising at least one polyol component, at least one isocyanate component, catalyst, foam stabilizer, blowing agent and optional auxiliaries, characterized in that the polyol component comprises recycling polyol, the polydispersity of this recycling polyol being <2 , preferably <1.5, in particular <1.2.

12. The composition of claim 11, that based on the total polyol component more than 30 wt .-%, preferably more than 50 wt .-%, preferably more than 70 wt .-%, more preferably more than 80 wt .-%, in particular more than 95% by weight recycling polyol with a polydispersity <2, preferably <1.5, in particular <1.2 is present.

13. Polyurethane foam, preferably PU rigid foam, PU flexible foam, PU hot flexible foam, viscoelastic PU foam, HR PU foam, PU hypersoft foam, semi-rigid PU foam, thermoformable PU foam or PU integral foam, preferably PU - Hot flexible foam, HR PU foam, PU hypersoft foam or viscoelastic PU foam, most preferably PU hot flexible foam, characterized in that it is obtained by a process according to any one of claims 1 to 10.

14. Use of polyurethane foams according to claim 13 as refrigerator insulation, insulating board, sandwich element, pipe insulation, spray foam, 1- & 1, 5-component canned foam, imitation wood, model foam, packaging foam, mattress, furniture upholstery, automobile seat upholstery, headrest, instrument panel, automobile Interior trim, automotive headliner, sound absorbing material, steering wheel, shoe sole, carpet backing foam, filter foam, sealing foam, sealant and adhesive, coating or to manufacture related products.