DE102024106836A1 - Process for obtaining polyols from polyurethane waste - Google Patents

Abstract

A process for obtaining polyols from polyurethane waste is described.

Description

The present invention relates to a process for obtaining polyols from polyurethane waste.

DE 199 17 932 A1 discloses a process for producing polyols by depolymerizing polyurethane waste, wherein polyurethane waste is introduced into a mixture of at least one diol and at least one primary and/or secondary aliphatic amine at temperatures of 120°C to 220°C and reacted, wherein the mixture contains diol and amine in a weight ratio of 1:1 to 10:1, and this mixture is used to the polyurethane in a weight ratio of up to 1:12.

DE 10 2009 026 898 A1 discloses a process for producing polyol components for polyurethanes from polyurethane rigid foam waste by combined aminolysis and glycolysis, characterized in that during or after the reaction of the polyurethane rigid foam waste with a known mixture of one or more low-molecular-weight glycols and one or more aliphatic amines, one or more long-chain saturated and/or unsaturated fatty acids are added under reaction conditions such that amide formation occurs. In practice, however, our own experiments have shown that amide formation with fatty acids proceeds relatively slowly and is accompanied by undesirable side reactions.

1. (1) Umsetzen
   1. (a) von Polyurethan-Abfällen mit
   2. (b) einer oder mehreren Verbindungen aus der Gruppe der Diole mit 2 bis 8 Kohlenstoffatomen und der Triole mit 3 bis 8 Kohlenstoffatomen und
   3. (c) einer oder mehreren Verbindungen aus der Gruppe der aliphatischen Amine und cycloaliphatischen Amine zu einer Reaktionsmischung,
2. (2) Umsetzen der in Schritt (1) gebildeten Reaktionsmischung mit
   1. (d) einer oder mehreren Verbindungen aus der Gruppe der Dicarbonsäuren und Dicarbonsäureanhydride zu einer Zusammensetzung enthaltend ein oder mehrere aus den Polyurethanabfällen (a) gebildete Polyole.

According to the invention, a process for obtaining polyols from polyurethane waste is proposed, which process comprises the following steps:

1. (1) Implement
   1. (a) of polyurethane waste with
   2. (b) one or more compounds from the group of diols having 2 to 8 carbon atoms and triols having 3 to 8 carbon atoms and
   3. (c) one or more compounds from the group of aliphatic amines and cycloaliphatic amines to form a reaction mixture,
2. (2) reacting the reaction mixture formed in step (1) with
   1. (d) one or more compounds from the group of dicarboxylic acids and dicarboxylic anhydrides to form a composition containing one or more polyols formed from the polyurethane waste (a).

Surprisingly, it has been found that advantageous effects are achieved by reacting the reaction mixture formed in step (1) with one or more compounds (d) from the group of dicarboxylic acids and dicarboxylic anhydrides in step (2) (for details see below).

The process according to the invention produces a composition containing one or more polyols formed from the polyurethane waste (a). These polyols are not identical to the compounds (b) added in step (1) from the group of diols having 2 to 8 carbon atoms and triols having 3 to 8 carbon atoms.

In step (1) of the process, the urethane groups in the polyurethane waste (a) are cleaved by glycolysis and aminolysis.

In step (2) of the process, further cleavage of the urethane groups in the polyurethane waste (a) takes place by acidolysis. In step (2), polyester polyols can also be formed by esterification or transesterification of polyols formed from the polyurethane waste (a) with one or more of the compounds (d) added in step (2) from the group of dicarboxylic acids and dicarboxylic anhydrides. Thus, chain extension of short-chain polyols formed from the polyurethane waste (a) is advantageously carried out by esterification with compounds (d) added in step (2) from the group of dicarboxylic acids and dicarboxylic anhydrides, resulting in polyester polyols having chain lengths and molecular weights similar to the primary polyols for the production of rigid foams. Thus, by suitable selection of the bonds (d) (acids and/or acid anhydrides) and their amounts, the average molecular weight and the molecular weight distribution of the resulting polyols can be adjusted as desired, so that the properties of the resulting polyols can be improved or adjusted for different applications.

Preferably, steps (1) and (2) of the process as defined above are carried out under a protective gas atmosphere, particularly preferably under a nitrogen atmosphere.

Preferably, the reaction mixture is stirred vigorously throughout the entire process.

• Schritt (1) eine Umsetzung
  1. (a) von Polyurethan-Abfällen mit
  2. (b) einer oder mehreren Verbindungen aus der Gruppe der Diole mit 2 bis 8 Kohlenstoffatomen und der Triole mit 3 bis 8 Kohlenstoffatomen und
  3. (c) einer oder mehreren Verbindungen aus der Gruppe der aliphatischen Amine und cycloaliphatischen Amine unter Rückfluss umfasst und
• Schritt (2) eine Umsetzung der in Schritt (1) gebildeten Reaktionsmischung mit
  1. (d) einer oder mehreren Verbindungen aus der Gruppe der Dicarbonsäuren und Dicarbonsäureanhydride
  unter Abdestillieren von Bestandteilen der Reaktionsmischung mit einem Siedepunkt ≤ 100 °C, bevorzugt ≤ 110°C, besonders bevorzugt ≤ 120 °C umfasst.

Preferably, the method defined above is carried out in such a way that

• Step (1) an implementation
  1. (a) of polyurethane waste with
  2. (b) one or more compounds from the group of diols having 2 to 8 carbon atoms and triols having 3 to 8 carbon atoms and
  3. (c) one or more compounds from the group of aliphatic amines and cycloaliphatic amines under reflux and
• Step (2) a reaction of the reaction mixture formed in step (1) with
  1. (d) one or more compounds from the group of dicarboxylic acids and dicarboxylic anhydrides
  by distilling off components of the reaction mixture having a boiling point ≤ 100 °C, preferably ≤ 110 °C, particularly preferably ≤ 120 °C.

• - flüchtige organische Verbindungen (VOC),
• - in Schritt (1) nicht verbrauchte Amine,
• - Wasser (das u.a. in Schritt (2) bei der oben erwähnten Veresterung aus den Polyurethan-Abfällen (a) gebildeter Polyole entsteht).

The components of the reaction mixture with a boiling point ≤ 100 °C, preferably ≤ 110 °C, particularly preferably ≤ 120 °C to 110 °C, which distill off, include in particular

• - volatile organic compounds (VOCs),
• - amines not consumed in step (1),
• - Water (which is produced, among other things, in step (2) during the above-mentioned esterification of polyols formed from the polyurethane waste (a)).

The preferred method of distillation is atmospheric distillation.

Preferably, at the end of step (1), before the addition of one or more compounds from the group of dicarboxylic acids and dicarboxylic anhydrides in step (2), the distillation is switched from reflux to atmospheric distillation. This ensures that any amine not consumed in step (1) is removed from the reaction mixture, so that the compounds from the group of dicarboxylic acids and dicarboxylic anhydrides added in step (2) are not consumed to neutralize excess amine from step (1).

In the process according to the invention, polyurethane waste (a) is preferably used in a total amount of 30 wt% to 75 wt%, particularly preferably 35 wt% to 55 wt%, based on the total mass of the substances (a), (b), (c) and (d) as defined above as 100 wt%.

In the process according to the invention, compounds (b) from the group of diols having 2 to 8 carbon atoms and triols having 3 to 8 carbon atoms are preferably used in a total amount of 20 wt% to 50 wt%, particularly preferably 25 wt% to 45 wt%, based on the total mass of substances (a), (b), (c) and (d) as defined above as 100 wt%.

In the process according to the invention, compounds (c) from the group of aliphatic amines and cycloaliphatic amines are preferably used in a total amount of 2 wt% to 15 wt%, particularly preferably 2.5 wt% to 8 wt%, based on the total mass of substances (a), (b), (c) and (d) as defined above as 100 wt%.

In the process according to the invention, compounds (d) from the group of dicarboxylic acids and dicarboxylic anhydrides are preferably used in a total amount of 3 wt% to 25 wt%, more preferably 5 wt% to 20 wt%, particularly preferably 6 wt% to 12 wt%, based on the total mass of the substances (a), (b), (c) and (d) as defined above as 100 wt%.

There are no restrictions on the type and composition of polyurethane waste in the process according to the invention. Polyurethane waste that can be processed using the process according to the invention includes both post-production waste and post-consumer waste, e.g., PUR and/or PUR/PIR rigid foams, semi-rigid foams, cellular and/or microcellular polyurethane elastomers, flexible polyurethane foams from insulation boards and panels, PUR and PUR/PIR building insulation, furniture, refrigerators, upholstery, pillows, mattresses, car seats, steering wheels, and shoe soles, etc. The polyurethane waste can contain, for example, fillers and/or additives. The polyurethane waste can, for example, be solid or foamed.

For process-related reasons, it is often preferable to separate polyurethane waste as far as possible from foreign components such as textiles, steel, wood and other foreign components.

The process according to the invention is also suitable for polyurethane waste in which polyurethane is combined with thermoplastics such as polyolefins, ABS, or PVC, and is difficult to separate from them. Such thermoplastics are dispersed in the composition produced according to the invention and can be removed from the composition produced according to the invention by solid/liquid separation, e.g., by filtration.

Polyurethane waste is preferably used in shredded form. The degree of shredding is freely selectable, with a higher degree of shredding being advantageous in terms of the speed at which the polyurethane waste is processed.

The process according to the invention is suitable, for example, for the processing of polyurethane foam waste, in particular for the processing of flexible polyurethane foams, flexible polyurethane foams, cellular and microcellular polyurethane materials, polyurethane elastomers, integral polyurethane foam, semi-rigid polyurethane foams, thermoplastic polyurethanes (TPU), rigid polyurethane foams, polyisocyanurates (PIR), PUR/PIR rigid foams, and unfoamed polyurethane materials. The polyurethane waste can be processed using the process according to the invention in sorted or unsorted form, with the polyurethane waste preferably containing only one material type, such as rigid foam, semi-rigid foam, flexible foam, cellular elastomer, or unfoamed elastomer. These material types are explained in more detail below. For polyurethane waste of one material type, it is not necessary to provide pure polyurethane waste, and thus, complex pre-sorting of the polyurethane waste can advantageously be omitted.

The process according to the invention is suitable, for example, for the processing of various types of polyurethane foam waste (rigid foam, semi-rigid foam, flexible foam).

In case of doubt, flexible polyurethane foams have an open cell structure or a partially open cell structure. They are manufactured using a wide variety of technologies and processes, such as continuous block or discontinuous box manufacturing processes, as well as free-form or molded foam, and are known to those skilled in the art under the following terms: PU block foam, cold foam, standard polyurethane flexible foam, HR-PU foam (high resilience polyurethane foam), viscoelastic polyurethane foam (memory PU foam), PU molded foam, polymer polyol flexible foams (POP flexible foams), SAN (styrene acrylonitrile) filled flexible foams, etc. The aforementioned flexible polyurethane foams are manufactured in a wide variety of densities (typically from 10 kg/m ³ , e.g. packing foam, to over 200 kg/m ³ , e.g. for technical applications) and are predominantly used in the manufacture of mattresses, in the furniture industry, automotive applications, and also as technical flexible foams and packaging material.

Polyurethane flexible foams can have an open cell structure, a hardness of 300 N to 500 N at 40% load measured according to SS-EN ISO 2439:2008(E) and an elasticity of 25% to 60% (measured according to EN ISO 8307).

Cellular and microcellular polyurethane elastomers exhibit an open-cell or closed-cell structure. Integral rigid foams, a variation of cellular and microcellular polyurethane elastomers, feature a porous core and a nearly solid outer layer and are manufactured by reaction injection molding in a mold or by the reaction injection molding (RIM) process. Cellular and microcellular polyurethane elastomers can be manufactured as flexible, semi-flexible, and rigid products. Typical applications include seat and molded cushions, headrests, armrests, and footrests for cars, bicycle saddles, steering wheel covers, and shoe soles (including midsoles and insoles).

Semi-rigid foams are significantly harder than flexible foams, but they lack the hardness or dimensional stability of rigid foams. The transition is smooth, however, and all required intermediate levels are adjustable. Semi-rigid foams are open-celled, do not form a significant skin during foaming, and have excellent adhesion to many covering materials. Semi-rigid foams are characterized by their optimal damping properties. Under impact, the energy is absorbed and distributed without a rubbery rebound. Rather, the foam slowly returns to its original shape. Due to their open-cell structure, semi-rigid foams also have special acoustic properties. Vibration damping contributes to the sustainable and long-lasting prevention of disturbing and creaking noises. Typical applications for semi-rigid polyurethane foams, which are characterized by their good energy absorption capacity, are side impact protection elements in doors and energy absorbers in bumpers. They are also used as energy absorbers in the pipeline and offshore industries, the automotive industry, and in sound wave reduction in house construction.

Rigid polyurethane foams are highly cross-linked and, in doubt, exhibit a closed-cell structure with higher compressive strength. The closed-cell density (i.e., the proportion of closed cells) is usually >90%. Due to their optimal insulating properties, rigid polyurethane foam insulation materials are versatile – both as insulation (e.g., for refrigerators and cooling systems, building insulation, etc.) and as a construction material in combination with cover layers made of other materials. Rigid polyurethane foams are thermosets, meaning they do not melt even at high temperatures and remain dimensionally stable. They are compression-resistant, durable, water-repellent, and resistant to almost all construction chemicals.

In case of doubt, rigid polyurethane foams have a closed cell structure with a compressive strength of at least 25 kPa (e.g. 1k can foam), in some cases at least 100 kPa (measured according to EN ISO 844:2009).

An important parameter for rigid polyurethane foams is the isocyanate index. Polyurethane (PUR) rigid foams have an isocyanate index <140, while polyurethane/polyisocyanurate rigid foams (PUR/PIR rigid foams) have an isocyanate index ≥ 140, typically from 140 to approximately 670, especially 140 to approximately 370. In the production of PUR/PIR, the isocyanate component is used in a higher excess than in the production of PUR. The isocyanate component then partially reacts with itself to form cross-linked isocyanurate ring structures. The high degree of cross-linking and the ring structures give the PUR/PIR rigid foam high mechanical and thermal stability. PIR is dimensionally stable. This rigid foam is ideal for the thermal insulation of fire-resistant components.

PUR, on the other hand, is advantageous when toughness and elasticity are important.

Preferably, the polyurethane waste (a) comprises one or more materials from the group consisting of rigid polyurethane foams, PUR/PIR rigid foams, semi-rigid polyurethane foams, flexible polyurethane foams and unfoamed polyurethanes, particularly preferably only one material type from the group consisting of rigid polyurethane foam, polyurethane/polyisocyanurate rigid foam, semi-rigid polyurethane foam, flexible polyurethane foam and unfoamed polyurethane.

The compounds (b) are preferably selected from the group consisting of ethylene glycol, diethylene glycol, dipropylene glycol, 1,3-propane glycol, 1,2-butanediol, 1,4-butane glycol and glycerol.

The compounds (b) cause a splitting of the polymer chains in the polyurethane waste (a) by glycolysis.

The compounds (c) are preferably selected from the group consisting of dibutylamine, N-ethylcyclohexylamine, dipropylenetriamine, 3,3'-diamino-N-methyldipropylamine, diethylenetriamine, ethylenediamine, hexamethylenediamine and triethylenediamine.

The compounds (c) cause a splitting of the polymer chains in the polyurethane waste (a) by aminolysis.

The compounds (d) are preferably selected from the group consisting of adipic acid, succinic acid, glutaric acid, malic acid, phthalic acid, maleic acid, dihalogenated phthalic acid, and tetrahalogenated phthalic acid, as well as their anhydrides, particularly preferably from the group consisting of adipic acid, maleic acid, phthalic acid, and succinic acid, as well as their anhydrides. Adipic acid is preferably not used as the sole compound (d). If adipic acid is used as compound (d), it is preferably used in combination with phthalic anhydride as a further compound (d).

The compounds (d) cause further cleavage of the polymer chains in the polyurethane waste (a) by acidolysis. In addition, reacting the reaction mixture formed in step (1) with one or more compounds (d) from the group of dicarboxylic acids and dicarboxylic anhydrides in step (2) causes one or more of the further advantageous effects described below:

The toxic primary aromatic amines (in particular toluenediamine (TDA) and methylenediphenyldiamine (MDA) and their isomers) formed during glycolysis from the diisocyanates of polyurethanes (typically toluene diisocyanate and/or methylenediphenyl diisocyanate) are reacted with compounds (d) from the group of dicarboxylic acids and dicarboxylic anhydrides to form the corresponding acid amides and/or acid imides.

By adding one or more compounds (d) from the group of dicarboxylic acids and dicarboxylic anhydrides, the hydroxyl number of the composition can be reduced if necessary.

Polyols formed from the polyurethane waste (a) as well as excess compounds (b) can form polyester polyols by esterification and/or transesterification with one or more of the compounds (d) added in step (2) from the group of dicarboxylic acids and dicarboxylic anhydrides. Thus, chain extension of short-chain polyols formed from the polyurethane waste (a) advantageously takes place, resulting in polyester polyols with chain lengths and molecular weights similar to the primary polyols for the production of rigid foams.

Particularly preferably, compounds (b), (c) and (d) are each selected from the groups of preferred compounds (b), (c) and (d) defined above.

1. (a) Polyurethan-Abfällen mit
2. (b) einer oder mehreren Verbindungen aus der Gruppe der Diole mit 2 bis 8 Kohlenstoffatomen und der Triole mit 3 bis 8 Kohlenstoffatomen und
3. (c) einer oder mehreren Verbindungen aus der Gruppe der aliphatischen Amine und cycloaliphatischen Amine

bei einer Temperatur im Bereich von 180°C bis 230°C, bevorzugt 190°C bis 225°C, besonders bevorzugt 200°C bis 215°C.Preferably, step (1) of the process according to the invention comprises a reaction of

1. (a) Polyurethane waste with
2. (b) one or more compounds from the group of diols having 2 to 8 carbon atoms and triols having 3 to 8 carbon atoms and
3. (c) one or more compounds from the group of aliphatic amines and cycloaliphatic amines

at a temperature in the range of 180°C to 230°C, preferably 190°C to 225°C, particularly preferably 200°C to 215°C.

For step (1) of the process according to the invention, the above-defined compounds (b) and (c) are usually initially charged at a maximum temperature of 120°C and then heated to a temperature in the range from 130°C to 230°C, preferably 150°C to 220°C, particularly preferably 160°C to 190°C. The polyurethane waste (a) is then metered in to form a reaction mixture. When metering in the polyurethane waste, the temperature is usually kept in the range from 130°C to 230°C, preferably 150°C to 220°C, particularly preferably 160°C to 210°C. The metered addition of the polyurethane waste is expediently carried out at a rate such that an excessive increase in viscosity and a drop in temperature are avoided, and can extend over one to several hours, typically up to 4 hours.

In certain cases, it is preferable to initially charge only a portion, e.g. 30 wt% to 40 wt%, of the total amount of the compounds (c) defined above, in addition to the total amount of the compounds (b) defined above, and to meter in the remaining amount of the compounds (c) defined above in parallel with the addition of the polyurethane waste (a).

To homogenize the reaction mixture, the polyurethane waste (a) is added under intensive stirring. The reaction mixture is preferably continuously stirred throughout the rest of the process.

After completion of the addition of the polyurethane waste, the reaction mixture is heated further if necessary and stirred for one hour, usually at a temperature in the range of 180°C to 230°C, preferably 190°C to 225°C, particularly preferably 200°C to 215°C.

The reaction mixture is then preferably cooled to a temperature in the range of 170°C to 190°C.

1. (d) einer oder mehreren Verbindungen aus der Gruppe der Dicarbonsäuren und Dicarbonsäureanhydride

bei einer Temperatur im Bereich von 215°C bis 235°C, bevorzugt 220°C bis 230°C, besonders bevorzugt 220°C bis 225°C.Preferably, step (2) of the process according to the invention comprises reacting the reaction mixture formed in step (1) with

1. (d) one or more compounds from the group of dicarboxylic acids and dicarboxylic anhydrides

at a temperature in the range of 215°C to 235°C, preferably 220°C to 230°C, particularly preferably 220°C to 225°C.

In step (2), the compounds (d) defined above are added as quickly as possible. In certain cases, it is preferable to initially add only a portion, e.g., 75% to 80% by weight, of the total amount of the compounds (d) defined above, and to add the remaining amount of the compounds (d) defined above at the end of step (2).

After adding the compounds (d) defined above, the reaction mixture is typically slowly heated to a temperature in the range of 215°C to 235°C, preferably 220°C to 230°C, particularly preferably 220°C to 225°C, and then held at this temperature. Heating to and subsequent holding at a temperature in the range of 215°C to 235°C, preferably 220°C to 230°C, particularly preferably 220°C to 225°C, can take several hours, typically up to 3 hours.

Thereafter, the reaction mixture is usually cooled to a temperature in the range of 180°C to 200°C and, if appropriate, the remaining amount of the compounds (d) defined above is added.

Particularly preferred includes

1. (a) von Polyurethan-Abfällen mit
2. (b) einer oder mehreren Verbindungen aus der Gruppe der Diole mit 2 bis 8 Kohlenstoffatomen und der Triole mit 3 bis 8 Kohlenstoffatomen und
3. (c) einer oder mehreren Verbindungen aus der Gruppe der aliphatischen Amine und cycloaliphatischen Amine

bei einer Temperatur im Bereich von 180°C bis 230°C, bevorzugt 190°C bis 225°C, besonders bevorzugt 200°C bis 215°C,
undStep (1) of the process according to the invention comprises reacting

1. (a) of polyurethane waste with
2. (b) one or more compounds from the group of diols having 2 to 8 carbon atoms and triols having 3 to 8 carbon atoms and
3. (c) one or more compounds from the group of aliphatic amines and cycloaliphatic amines

at a temperature in the range of 180°C to 230°C, preferably 190°C to 225°C, particularly preferably 200°C to 215°C,
and

1. (d) einer oder mehreren Verbindungen aus der Gruppe der Dicarbonsäuren und Dicarbonsäureanhydride

bei einer Temperatur im Bereich von 215°C bis 235°C, bevorzugt 220°C bis 230°C, besonders bevorzugt 220°C bis 225°C.Step (2) of the process according to the invention comprises reacting the reaction mixture formed in step (1) with

1. (d) one or more compounds from the group of dicarboxylic acids and dicarboxylic anhydrides

at a temperature in the range of 215°C to 235°C, preferably 220°C to 230°C, particularly preferably 220°C to 225°C.

Step (1) of the process according to the invention can be carried out in the presence of one or more catalysts. These catalysts accelerate the decomposition of the polyurethane waste. Particularly suitable catalysts for step (1) are those which are also used for the production of the corresponding polyurethanes or polyisocyanurates. The catalyst for step (1) of the process according to the invention is preferably selected from the group consisting of potassium 2-ethylhexanoate, potassium neodecanoate, and potassium acetate. Isocyanate trimerization catalysts, such as those available from Evonik under the brand name Dabco®, are also suitable. The catalyst is added during or after the addition of the polyurethane waste.

The addition of a catalyst, in particular from the group consisting of potassium 2-ethylhexanoate, potassium neodecanoate and potassium acetate as well as isocyanate trimerization catalysts such as those available under the brand Dabco® from Evonik, is particularly preferred when the polyurethane waste contains or consists of PUR/PIR rigid foams.

Step (2) of the process according to the invention can be carried out in the presence of a catalyst, preferably an esterification catalyst. The catalyst for step (2) of the process according to the invention is preferably selected from the group consisting of tetraisobutyl orthotitanate, titanium(IV)(triethanolaminato)isopropoxide, and tin(II) chloride.

In certain cases, it is preferred that both step (1) and step (2) of the process according to the invention are carried out in the presence of a catalyst. The catalysts are preferably selected from the groups defined above.

The composition formed in step (2) may comprise polyester polyols formed by esterification or transesterification of polyols formed from the polyurethane waste (a) with one or more compounds (d) from the group of dicarboxylic acids and dicarboxylic anhydrides.

• (3) Zugeben einer oder mehrerer Substanzen aus der Gruppe bestehend aus
  • - Weichmacher, vorzugsweise Propylencarbonat
  • - Katalysatoren für die Synthese von Polyurethan-Polyisocyanuraten, wobei der Katalysator bevorzugt ausgewählt ist aus der Gruppe bestehend aus Kalium 2-ethylhexanoat, Kaliumneodecanoat und Kaliumacetat
  • - Tenside
  • - Flammschutzmitteln

zu der in Schritt (2) erhaltenen Zusammensetzung, so dass eine modifizierte Zusammensetzung resultiert.In certain cases, the method according to the invention further comprises the step

• (3) Adding one or more substances from the group consisting of
  • - Plasticizer, preferably propylene carbonate
  • - Catalysts for the synthesis of polyurethane polyisocyanurates, wherein the catalyst is preferably selected from the group consisting of potassium 2-ethylhexanoate, potassium neodecanoate and potassium acetate
  • - Surfactants
  • - Flame retardants

to the composition obtained in step (2), so that a modified composition results.

The addition of the above-mentioned substances in step (3) serves to optimize certain properties of the composition produced by the process according to the invention or of the products to be produced therefrom. Thus, a modified composition specifically optimized and adjusted according to the properties of the polyurethane materials to be produced from the polyols obtained by the process according to the invention can be obtained.

The addition of propylene carbonate serves to reduce viscosity and/or acidity. Another effect, desired in certain cases, is that propylene carbonate acts as a plasticizer and reduces the brittleness of rigid foams. Plasticizers, especially propylene carbonate, are typically added in amounts of 0.5 wt% to 4 wt%, preferably 1 wt% to 2 wt%, based on the total mass of the composition. The addition of plasticizers, especially propylene carbonate, typically takes place at a temperature in the range of 110°C to 190°C, preferably 130°C to 190°C, particularly preferably 160°C to 190°C.

Addition of a catalyst for the synthesis of polyurethane polyisocyanurates, wherein the catalyst is preferably selected from the group consisting of potassium 2-ethylhexanoate, potassium neodecanoate and/or potassium acetate, takes place in particular when the polymers obtained by the process according to the invention The composition prepared is intended for the production of PUR/PIR. Potassium 2-ethylhexanoate, potassium neodecanoate, and potassium acetate are trimerization catalysts for the formation of polyisocyanurate (PIR). Catalysts for the synthesis of polyurethane polyisocyanurates, wherein the catalyst is preferably selected from the group consisting of potassium 2-ethylhexanoate, potassium neodecanoate, and potassium acetate, are typically added in amounts of 0.5 wt% to 4 wt%, preferably 1 wt% to 2 wt%, based on the total mass of the composition. The addition of catalysts typically takes place at a temperature in the range 110°C to 190°C, preferably 130°C to 190°C, particularly preferably 160°C to 190°C.

The addition of surfactants serves to reduce the viscosity and/or increase the cohesion and/or adhesion of a polyurethane produced from a composition prepared by the process according to the invention, e.g., the adhesion to a cover layer in the production of rigid polyurethane foam boards (see below for details). Surfactants are typically added in amounts of up to 4% by weight, based on the total mass of the composition. Surfactants are typically added at a maximum temperature of 140°C. Suitable surfactants are anionic and nonionic surfactants, particularly 4-nonylphenol and ethoxylated alcohols (alcohol ethoxylates), such as isotridecanol ethoxylate.

In certain cases, flame retardants are added. Flame retardants are typically added in amounts up to 18% by weight, based on the total mass of the composition. Flame retardants are typically added at a maximum temperature of 140 °C. Suitable flame retardants include tris(2-chloroisopropyl) phosphate (TCPP) and triethyl phosphate (TEP).

• (4) Filtrieren der in Schritt (2) erhaltenen Zusammensetzung bzw. der in Schritt (3) erhaltenen modifizierten Zusammensetzung.

In certain cases, the method according to the invention further comprises the step

• (4) filtering the composition obtained in step (2) or the modified composition obtained in step (3).

In such process designs which do not include step (3) defined above, step (4) takes place after step (2), i.e. the composition obtained in step (2) is filtered.

In such process configurations which comprise step (3) defined above, step (4) takes place after step (3), i.e. the modified composition obtained in step (3) is filtered.

Process designs are also possible in which the step (3) defined above takes place after the step (4) defined above.

Preferably, the filtration in step (4) takes place at a temperature in the range of 100°C to 150°C, particularly preferably 110°C to 130°C. Preferably, a filter with a pore size in the range of 50 µm to 200 µm is used. Particularly preferably, the filtration in step (4) takes place at temperatures in the range of 110°C to 130°C, using a filter with a pore size in the range of 50 µm to 200 µm. Particularly preferably, self-cleaning filters are used.

In a preferred variant, the temperature and time course of the process according to the invention is as shown in Table 1, wherein the entire process is preferably carried out under a nitrogen atmosphere and the reaction mixture is stirred throughout the entire process: Table 1 Step No. Temperature of the reaction mixture [°C] Time[h] (1) Submitting one or more compounds (b) and one or more compounds (c) ≤120 0.5 Heating under reflux 160-190 1 Dosing of the polyurethane waste (a) and, if necessary, the remaining amount of compounds (c) under reflux 160-210 1-4 Heating and homogenization under reflux 190-225 1 Reaction time under reflux 190-225 0.5 Cooling, switching from reflux to distillation 170-190 0.25 (2) Addition of one or more compounds (d) under distillation 170-190 0.5 Slow heating and reaction time during distillation 220-230 3 Cool 180-200 0.75 if necessary, add the remaining amount of compounds (d) 180-190 0.5 (3) Cool and add further ingredients if necessary 110-190 1.5 (4) Pumping and filtering 100-150

A composition produced by the process according to the invention comprises a liquid phase containing the polyols formed from the polyurethane waste. The liquid phase may also contain polyester polyols formed by esterification and/or transesterification of polyols formed from the polyurethane waste (a) with one or more compounds (d) from the group of dicarboxylic acids and dicarboxylic anhydrides. The liquid phase may also contain polyester polyols formed by esterification of compounds (b) with one or more of the compounds (d) added in step (2) from the group of dicarboxylic acids and dicarboxylic anhydrides.

A composition produced by the process according to the invention also contains reaction products formed during the decomposition of the polyurethane waste, which are dispersed in the liquid phase in the form of particles, e.g., oligourethanes (shorter urethane chains remaining after partial decomposition of the original polyurethanes), oligo- and polyureas, and acylureas. Amines, amides, and imides may be present as further degradation products of the polyurethane waste.

When polyurethane wastes containing polyurethane combined with thermoplastics such as polyolefins, ABS or PVC are used, the composition produced by the process according to the invention contains these thermoplastics in dispersed form; they can be removed from the composition by solid/liquid separation, e.g. by filtration, if necessary.

A composition prepared by the process according to the invention may contain unreacted residual polyurethane in the form of dispersed particles.

• - eine Hydroxylzahl von 200 bis 650 mg KOH/g, bevorzugt 200 bis 450 mg KOH/g (bestimmt nach DIN 53240), und/oder
• - eine Aminzahl von ≤ 50 mg KOH/g, bevorzugt 1 bis 40 mg KOH/g, besonders bevorzugt 10 bis 35 mg KOH/g (bestimmt nach DIN 53176) und/oder
• - eine Säurezahl von ≤ 15 mg KOH/g, bevorzugt 0,1 bis 8 mg KOH/g, besonders bevorzugt 0,1 bis 5 mg KOH/g (bestimmt nach DIN 53402) und/oder
• - eine Viskosität von ≤ 30000 mPa*s, besonders bevorzugt 3000 bis 8000 mPa*s (bestimmt nach DIN bestimmt nach DIN 53019)

auf.A composition produced by the process according to the invention generally has

• - a hydroxyl number of 200 to 650 mg KOH/g, preferably 200 to 450 mg KOH/g (determined according to DIN 53240), and/or
• - an amine number of ≤ 50 mg KOH/g, preferably 1 to 40 mg KOH/g, particularly preferably 10 to 35 mg KOH/g (determined according to DIN 53176) and/or
• - an acid number of ≤ 15 mg KOH/g, preferably 0.1 to 8 mg KOH/g, particularly preferably 0.1 to 5 mg KOH/g (determined according to DIN 53402) and/or
• - a viscosity of ≤ 30000 mPa*s, particularly preferably 3000 to 8000 mPa*s (determined according to DIN 53019)

on.

• - eine Hydroxylzahl von 200 bis 650 mg KOH/g, bevorzugt 200 bis 450 mg KOH/g (bestimmt nach DIN 53240) und
• - eine Aminzahl von ≤ 50 mg KOH/g, bevorzugt 1 bis 40 mg KOH/g, besonders bevorzugt 10 bis 35 mg KOH/g (bestimmt nach DIN 53176) und
• - eine Säurezahl von ≤ 15 mg KOH/g, bevorzugt 0,1 bis 8 mg KOH/g, besonders bevorzugt 0,1 bis 5 mg KOH/g (bestimmt nach DIN 53402) und
• - eine Viskosität von ≤ 30000 mPa*s, besonders bevorzugt 3000 bis 8000 mPa*s (bestimmt nach DIN bestimmt nach DIN 53019)

auf.Preferably, a composition produced by the process according to the invention comprises

• - a hydroxyl number of 200 to 650 mg KOH/g, preferably 200 to 450 mg KOH/g (determined according to DIN 53240) and
• - an amine number of ≤ 50 mg KOH/g, preferably 1 to 40 mg KOH/g, particularly preferably 10 to 35 mg KOH/g (determined according to DIN 53176) and
• - an acid number of ≤ 15 mg KOH/g, preferably 0.1 to 8 mg KOH/g, particularly preferably 0.1 to 5 mg KOH/g (determined according to DIN 53402) and
• - a viscosity of ≤ 30000 mPa*s, particularly preferably 3000 to 8000 mPa*s (determined according to DIN 53019)

on.

Preferably, the concentration of primary aromatic amines in the composition produced by the process according to the invention is less than 0.1% (less than 1000 ppm), preferably less than 0.05% (less than 500 ppm), based on the total mass of the composition. The primary aromatic amines include, in particular, toluenediamine (TDA) and methylenediphenyldiamine and their isomers.

Compositions produced by the process according to the invention are isocyanate-reactive and thus particularly suitable for the production of new polyurethane materials.

As a polyol component for the polyurethane formation, a mixture of polyol formed from polyurethane waste according to the process according to the invention and primary polyol (i.e. polyol not obtained by splitting polyurethane) is preferably used, preferably in a mass ratio of 1:9 to 8:2, preferably 4:6 to 6:4, and reacted in the usual way with a polyisocyanate component.

The process according to the invention is particularly suitable for the processing of polyurethane waste (a) in the form of rigid polyurethane foam, e.g., waste from the production of PUR/PIR rigid foam boards and panels. PUR/PIR rigid foam boards comprise a foam core made of rigid polyurethane foam and a casing (also referred to as a cover layer) that at least partially surrounds the foam core. The casing typically comprises a lower and an upper cover layer. The cover layers are formed, for example, from materials from the group consisting of polymers that are not polyurethanes, mineral fleeces, glass fleeces, papers, metal foils, composite films, roofing membranes, or sealing membranes.

Sheet-shaped workpieces made of rigid polyurethane foam are used as insulation materials. Rigid polyurethane foam insulation materials are manufactured, for example, as sheets using the double-plate conveyor process. In the double-plate conveyor process, a reaction mixture comprising at least one polyol and at least one diisocyanate to form polyurethane, as well as at least one blowing agent, flows from a mixing head onto a lower cover layer, foams up, and bonds to an upper cover layer in the desired insulation thickness. The sheets are continuously manufactured using the double-plate conveyor process. This is usually followed by machining with cutting tools to cut the sheets to size or to apply profiles to the sheets, for example in the form of grooves, tongues, or shoulders. During the processing of the sheets, typically 1000 kg/24h to 2000 kg/24h of production waste in the form of chips and milling residues are generated.

• - ein spanendes Bearbeitungsmittel zum Bearbeiten der plattenförmigen Werkstücke, das dazu eingerichtet ist, den Schaumkern und die Verschalung separat voneinander spanend zu bearbeiten, und
• - eine Abführvorrichtung, vorzugsweise eine Absaugeinrichtung, welche dazu eingerichtet ist, die bei der spanenden Bearbeitung des Schaumkerns entstehenden Schaumspäne abzuführen.

Preferably, the machining of the polyurethane rigid foam insulation materials is carried out with a device comprising

• - a machining means for machining the plate-shaped workpieces, which is designed to machine the foam core and the formwork separately, and
• - a removal device, preferably a suction device, which is designed to remove the foam chips produced during the machining of the foam core.

The removed foam chips can be used as polyurethane waste (a) in the process according to the invention. The foam chips are preferably removed in a sorted form. The term "sorted" in this context refers to foam chips that have a PUR or PUR/PIR foam content of ≥ 95 wt%, preferably ≥ 98 wt%.

The machining means is preferably designed as a milling machine with at least one first milling head and at least one second milling head, wherein the first milling head is configured to machine the formwork and the second milling head is configured to machine the foam core.

Preferably, the suction device has a suction means assigned to the second milling head for sucking the foam chips produced during the machining of the foam core from the second milling head.

Preferably, the removal device is further configured to remove the chips generated during the machining of the formwork of the rigid polyurethane foam panels separately from the foam chips. For this purpose, the suction device preferably has a suction means associated with the first milling head for removing the chips generated during the machining of the formwork from the first milling head.

• - spanendes Abtragen der Verschalung in einem Bearbeitungsbereich, insbesondere vollständiges Abtragen der Verschalung in dem Bearbeitungsbereich,
• - spanendes Bearbeiten ausschließlich des Schaumkerns in dem Bearbeitungsbereich,
• - Abführen, insbesondere Absaugen, der bei der spanenden Bearbeitung des Schaumkerns entstehenden Schaumspäne.

The polyurethane rigid foam boards are preferably manufactured using a process comprising the steps:

• - machining of the formwork in a processing area, in particular complete removal of the formwork in the processing area,
• - machining only the foam core in the machining area,
• - Removal, in particular suction, of the foam chips produced during machining of the foam core.

The removed foam chips can be used in the process according to the invention as polyurethane waste (a) for producing a composition.

The process according to the invention is also suitable for the processing of polyurethane waste (a) in the form of rigid polyurethane foam from the slabstock foam process. In the slabstock foam process, the reaction mixture flows from a mixing head into a block mold or onto a continuous block conveyor. After foaming and settling, the blocks are cut into sheets or processed into molded parts (e.g., wedges, pipe shells). The slabstock foam process generates up to 25% by weight of production waste, based on the total mass of the slabstock foam produced.

When designing a reaction device for the process according to the invention, it must be taken into account that the process takes place at high temperatures in the presence of corrosive substances (acid anhydrides and/or acids). Therefore, it is preferred that the reaction takes place in a container made of stainless steel. Particularly preferably, the entire reaction device and peripherals are made of corrosion- and acid-resistant stainless steel. In certain embodiments, the device contains a fractionation or distillation device, e.g., in the form of a column, and suitable metering devices.

The following examples serve to further illustrate the invention but are not limiting.

1. 1) einen Reaktor, vorzugsweise aus Edelstahl
2. 2) einen Rührer zum Rühren der Reaktionsmischung
3. 3) eine Dosierschnecke zum Dosieren der Polyurethan-Abfälle
4. 4) eine Fraktionskolonne, vorzugsweise eine Doppelmantel-Fraktionskolonne
5. 5) einen Dephlegmator
6. 6) einen Kondensator
7. 7) ein Dreiwegeventil
8. 8) eine Pumpe
9. 9) einen Destillat-Behälter
10. 10) einen Nachkondensator
11. 11) ein Temperiergerät
12. 12) eine Vorrichtung für die Aufnahme des Destillat-Rückflusses

To carry out the examples, the 1 The system shown is used. This system includes:

1. 1) a reactor, preferably made of stainless steel
2. 2) a stirrer for stirring the reaction mixture
3. 3) a dosing screw for dosing the polyurethane waste
4. 4) a fractional column, preferably a double-jacketed fractional column
5. 5) a dephlegmator
6. 6) a capacitor
7. 7) a three-way valve
8. 8) a pump
9. 9) a distillate container
10. 10) a post-condenser
11. 11) a temperature control device
12. 12) a device for receiving the distillate reflux

Example 1:

Process step (1)

In the stainless steel reactor 1 of a plant according to 1 41.7 wt% diethylene glycol and 3 wt% dibutylamine were initially charged and heated to 160 °C under reflux within 60 minutes.

At a reactor temperature between 160°C and 200°C, 40 wt% unsorted PUR/PIR rigid foam waste (shredded and compacted, containing up to 2 wt% impurities) was added over a period of 3 hours under reflux and nitrogen blanketing. The mixture was continuously stirred until the waste was dispersed and dissolved. Parallel to the addition and dissolution of the PUR/PIR rigid foam waste, 1.1 wt% potassium 2-ethylhexanoate (Kosmos® 75) was gradually added. During the addition and dissolution of the PUR/PIR rigid foam waste under reflux, the column head temperature was kept below 60°C by the cooling medium in the column jacket and dephlegmator.

The temperature was then increased to 210°C and the reaction mixture was stirred under reflux for one hour.

Process step (2)

After cooling the reaction mixture to 180°C and switching from reflux to atmospheric distillation, 3.5 wt% adipic acid, 6.5 wt% phthalic anhydride, and 30 ppm tetraisobutyl orthotitanate were added. The column head temperature was maintained at 105°C by controlled temperature control of the column jacket and dephlegmator.

During the subsequent reaction, the temperature of the reaction mixture was gradually increased to 230°C depending on the column head temperature and distillate flow.

The reaction mixture was stirred for a further hour at a temperature of 230°C and then cooled to 190°C with stirring. When the reaction mixture temperature was in the range of 180°C to 190°C, 1 wt% maleic anhydride was added and stirring continued for a further 30 minutes.

Process step (3)

Then, 1.2 wt% potassium 2-ethylhexanoate and 2 wt% propylene carbonate were added and stirring was continued for another 30 minutes.

The resulting composition was cooled to 125°C. Subsequently, 1.2 wt% of an alcohol ethoxylate and 7.0 wt% of TCPP were added (each based on the mass of the composition after the addition of potassium 2-ethylhexanoate and propylene carbonate as 100%), and homogenized for 30 minutes.

Process step (4)

The modified composition formed in process step (3) was then pumped out, filtered through a self-cleaning filter (pore size 100 µm), and cooled to room temperature. The residual solids amounted to 2.7 wt%, based on the total mass of the modified composition before filtration.

• Die filtrierte Zusammensetzung hatte folgende Eigenschaften
• Hydroxylzahl: 385 mg KOH/g, gemessen nach DIN 53240
• Säurezahl: 1,8 mg KOH/g, gemessen nach DIN 53402
• Aminzahl: 24 mg KOH/g, gemessen nach DIN 53176
• Viskosität: 4.800 m Pa*s bei 25°C, gemessen nach DIN 53019

Thus, a composition was obtained whose content of primary aromatic amines was below 0.1 wt% (below 1000 ppm).

• The filtered composition had the following properties
• Hydroxyl number: 385 mg KOH/g, measured according to DIN 53240
• Acid number: 1.8 mg KOH/g, measured according to DIN 53402
• Amine number: 24 mg KOH/g, measured according to DIN 53176
• Viscosity: 4,800 m Pa*s at 25°C, measured according to DIN 53019

This composition is suitable for the production of new PUR/PIR rigid foams. Its proportion of the total polyol used can be up to 80 wt%.

Example 2:

Process step (1)

In the stainless steel reactor 1 of a plant according to 1 42.8 wt% diethylene glycol, 2 wt% dibutylamine and 2% ethylcyclohexylamine were initially charged and heated to 170°C under reflux within 60 minutes.

At a reactor temperature between 160°C and 200°C, 40 wt% unsorted polyurethane rigid foam waste from discarded refrigerators (shredded and compacted, containing up to 1.2 wt% impurities) was added over a period of 2 hours under reflux and nitrogen blanketing. The mixture was continuously stirred until the waste was dispersed and dissolved. The column head temperature was maintained below 40°C by the cooling medium in the column jacket and dephlegmator.

The temperature was then increased to 210°C and the reaction mixture was stirred under reflux for one hour.

Process step (2)

After cooling the reaction mixture to 180°C and switching from reflux to atmospheric distillation, 3 wt% adipic acid and 7.5 wt% phthalic anhydride were added. The column head temperature was maintained at 110°C by controlling the temperature of the column jacket and dephlegmator.

During the subsequent reaction, the temperature of the reaction mixture was gradually increased to 227°C depending on the column head temperature and distillate flow.

The reaction mixture was stirred for a further hour at 227°C and then cooled to 190°C with stirring. At a reaction temperature of 180°C to 190°C, 1.7 wt% maleic anhydride was added and stirring continued for a further 30 minutes. The resulting composition was then cooled to 125°C.

Process step (4)

The cooled composition was pumped off, filtered through a self-cleaning filter (pore size 100 µm), and cooled to room temperature. The residual solids amounted to 1.8 wt% based on the total mass of the composition before filtration.

Thus, a composition was obtained whose content of primary aromatic amines was below 0.1 wt% (below 1000 ppm).

• Hydroxylzahl: 405 mg KOH/g, gemessen nach DIN 53240
• Säurezahl: 0,9 mg KOH/g, gemessen nach DIN 53402
• Aminzahl: 28 mg KOH/g, gemessen nach DIN 53176
• Viskosität: 5.700 m Pa*s bei 25°C, gemessen nach DIN 53019

The filtered composition had the following properties:

• Hydroxyl number: 405 mg KOH/g, measured according to DIN 53240
• Acid number: 0.9 mg KOH/g, measured according to DIN 53402
• Amine number: 28 mg KOH/g, measured according to DIN 53176
• Viscosity: 5,700 m Pa*s at 25°C, measured according to DIN 53019

This composition is suitable for the production of new PUR/PIR and PUR rigid foams.

Example 3:

Process step (1)

In the stainless steel reactor 1 of a plant according to 1 38 wt% diethylene glycol and 4.5 wt% glycerol (propane-1,2,3-triol), 1.8 wt% N-ethylcyclohexanamine and 1.5 wt% 3,3'-diamino-N-methyldipropylamine were initially charged and heated to 170°C under reflux within 40 minutes.

At a reactor temperature between 160°C and 190°C, 43.5 wt% unsorted post-consumer polyurethane flexible foam waste (shredded and compacted, containing up to 0.5 wt% impurities) was added over a period of 2.5 hours under reflux and nitrogen blanketing. The mixture was continuously stirred until the waste was dispersed and dissolved. The column head temperature was maintained below 40°C by the cooling medium in the column jacket and dephlegmator.

The temperature was then increased to 220°C and the reaction mixture was stirred under reflux for 40 minutes.

Process step (2)

After cooling the reaction mixture to 180°C and switching from reflux to atmospheric distillation, 9.5 wt% phthalic anhydride and 30 ppm tetraisobutyl orthotitanate were added. The column head temperature was maintained at 110°C by controlled temperature control of the column jacket and dephlegmator.

During the subsequent reaction, the temperature of the reaction mixture was gradually increased to 225°C depending on the column head temperature and distillate flow.

The reaction mixture was stirred for a further hour at 225°C and then cooled to 190°C with stirring. When the reaction mixture reached a temperature in the range of 180°C to 190°C, 1.2 wt% maleic anhydride was added and stirring continued for a further 30 minutes. The resulting composition was then cooled to 115°C.

Process step (4)

The cooled composition was pumped off, filtered through a self-cleaning filter (pore size 100 µm), and cooled to room temperature. The residual solids amounted to 0.4 wt% based on the total mass of the composition before filtration.

Thus, a composition was obtained whose content of primary aromatic amines was below 0.1 wt% (below 1000 ppm).

• Hydroxylzahl: 277 mg KOH/g, gemessen nach DIN 53240
• Säurezahl: 1,2 mg KOH/g, gemessen nach DIN 53402
• Aminzahl: 21 mg KOH/g, gemessen nach DIN 53176
• Viskosität: 4.900 m Pa*s bei 25°C, gemessen nach DIN 53019

The filtered composition had the following properties:

• Hydroxyl number: 277 mg KOH/g, measured according to DIN 53240
• Acid number: 1.2 mg KOH/g, measured according to DIN 53402
• Amine number: 21 mg KOH/g, measured according to DIN 53176
• Viscosity: 4,900 m Pa*s at 25°C, measured according to DIN 53019

This composition is suitable for the production of new PUR/PIR rigid foams.

Example 4:

Process step (1)

In the stainless steel reactor 1 of a plant according to 1 23.4 wt% diethylene glycol, 3 wt% 1,4-butanediol and 5.5 wt% glycerol, 1.1 wt% N-ethylcyclohexanamine and 1.5 wt% dibutylamine were initially charged and heated to 160°C under reflux within 60 minutes.

At a reactor temperature between 160°C and 190°C, 53 wt% unsorted polyurethane integral skin foam waste and microcellular polyurethane elastomers (production waste from shoe sole production and steering wheel production in a ratio of 4:3) were added over a period of 2 hours under reflux and nitrogen blanketing. The mixture was continuously stirred until the waste was dispersed and dissolved. The column head temperature was maintained below 40°C by the cooling medium in the column jacket and dephlegmator.

The temperature was then increased to 220°C and the reaction mixture was stirred under reflux for 40 minutes.

Process step (2)

After cooling the reaction mixture to 180°C and switching from reflux to atmospheric distillation, 2.5 wt% adipic acid, 8.5 wt% phthalic anhydride, and 35 ppm tetraisobutyl orthotitanate were added. The column head temperature was maintained at 110°C by controlled temperature control of the column jacket and dephlegmator.

During the subsequent reaction, the temperature of the reaction mixture was gradually increased to 220°C depending on the column head temperature and distillate flow.

The reaction mixture was stirred for a further hour at 220°C and then cooled to 190°C with stirring. When the reaction mixture reached a temperature in the range of 180°C to 190°C, 1.2 wt% maleic anhydride was added and stirring continued for a further 30 minutes. The resulting composition was then cooled to 115°C.

Process step (4)

The cooled composition was pumped off, filtered through a self-cleaning filter (pore size 100 µm), and cooled to room temperature. The residual solids amounted to 0.2 wt% based on the total mass of the composition before filtration.

Thus, a composition was obtained whose content of primary aromatic amines was below 0.1 wt% (below 1000 ppm).

• Hydroxylzahl: 310 mg KOH/g, gemessen nach DIN 53240
• Säurezahl: 0,8 mg KOH/g, gemessen nach DIN 53402
• Aminzahl: 18 mg KOH/g, gemessen nach DIN 53176
• Viskosität:8.900 m Pa*s bei 25°C, gemessen nach DIN 53019

The filtered composition had the following properties:

• Hydroxyl number: 310 mg KOH/g, measured according to DIN 53240
• Acid number: 0.8 mg KOH/g, measured according to DIN 53402
• Amine number: 18 mg KOH/g, measured according to DIN 53176
• Viscosity: 8,900 m Pa*s at 25°C, measured according to DIN 53019

This composition is suitable for the production of new PUR/PIR rigid foams.

Example 5:

Process step (1)

In the stainless steel reactor 1 of a plant according to 1 41 wt% diethylene glycol, 2.9 wt% dibutylamine were initially charged and heated to 170°C under reflux within 60 minutes.

At a reactor temperature between 170°C and 205°C, 40 wt% unsorted PUR/PIR rigid foam waste (shredded and compacted) was added over a period of 3 hours under reflux and nitrogen blanketing. The reactor was continuously stirred until the waste was dispersed and dissolved. Parallel to the addition and dissolution of the PUR/PIR rigid foam waste, 1.2 wt% potassium 2-ethylhexanoate (Kosmos® 75) was gradually added. During the addition and dissolution of the PUR/PIR rigid foam waste under reflux, the column head temperature was kept below 60°C by the cooling medium in the column jacket and dephlegmator.

The temperature was then increased to 215°C and the reaction mixture was stirred under reflux for one hour.

Process step (2)

After cooling the reaction mixture to 180°C and switching from reflux to atmospheric distillation, 3.2 wt% adipic acid, 8.2 wt% phthalic anhydride, and 30 ppm tetraisobutyl orthotitanate were added. The column head temperature was maintained at 110°C by controlled temperature control of the column jacket and dephlegmator.

During the subsequent reaction, the temperature of the reaction mixture was gradually increased to 230°C depending on the column head temperature and distillate flow.

The reaction mixture was stirred for a further hour at a temperature of 230°C and then cooled to 190°C with stirring. When the reaction mixture temperature was in the range of 180°C to 190°C, 1 wt% maleic anhydride was added and stirring continued for a further 30 minutes.

Process step (3)

Then, 1 wt% potassium ocoate and 2 wt% propylene carbonate were added, and stirring was continued for a further 30 minutes. The final composition was then cooled to 125°C. Subsequently, 1.1 wt% of an alcohol ethoxylate (SASOL-MARLIPAL O 13/90) and 6.5 wt% TCPP (each based on the mass of the composition after the addition of potassium 2-ethylhexanoate and propylene carbonate as 100%) were added, and the mixture was homogenized for 30 minutes.

Process step (4)

The modified composition formed in process step (3) was then pumped out, filtered through a self-cleaning filter (pore size 100 µm), and cooled to room temperature. The residual solids amounted to 0.12 wt% based on the total mass of the modified composition before filtration.

Thus, a composition was obtained whose content of primary aromatic amines was below 0.1 wt% (below 1000 ppm).

• Hydroxylzahl: 368 mg KOH/g, gemessen nach DIN 53240
• Säurezahl: 1,8 mg KOH/g, gemessen nach DIN 53402
• Aminzahl: 18 mg KOH/g, gemessen nach DIN 53176
• Viskosität: 7.600 m Pa*s bei 25°C, gemessen nach DIN 53019

The filtered composition had the following properties:

• Hydroxyl number: 368 mg KOH/g, measured according to DIN 53240
• Acid number: 1.8 mg KOH/g, measured according to DIN 53402
• Amine number: 18 mg KOH/g, measured according to DIN 53176
• Viscosity: 7,600 m Pa*s at 25°C, measured according to DIN 53019

This composition is suitable for the production of new PUR/PIR rigid foams.

Example 6:

Process step (1)

In the stainless steel reactor 1 of a plant according to 1 43.7 wt% diethylene glycol and 2.5 wt% N-ethylcyclohexylamine were initially charged and heated to 170°C under reflux within 60 minutes.

At a reactor temperature between 170°C and 205°C, 41 wt% of unsorted PUR/PIR rigid foam waste (shredded and compacted) was added over a period of 3 hours under reflux and nitrogen blanketing. The reactor was continuously stirred until the waste was dispersed and dissolved. Parallel to the addition and dissolution of the PUR/PIR rigid foam waste, 1.3 wt% of the catalyst DABCO® TMR 30 (Evonik) was gradually added. During the addition and dissolution of the PUR/PIR rigid foam waste under reflux, the column head temperature was kept below 40°C by the cooling medium in the column jacket and dephlegmator.

The temperature was then increased to 215°C and the reaction mixture was stirred under reflux for one hour.

Process step (2)

After cooling the reaction mixture to 180°C and switching from reflux to atmospheric distillation, 3 wt% adipic acid and 7 wt% phthalic anhydride were added. The column head temperature was kept below 105°C by controlling the temperature of the column jacket and dephlegmator.

During the subsequent reaction, the temperature of the reaction mixture was gradually increased to 230°C depending on the column head temperature and distillate flow.

The reaction mixture was stirred for a further hour at 230°C and then cooled to 190°C while stirring. When the reaction mixture reached a temperature in the range of 180°C to 190°C, 1.5 wt% maleic anhydride was added and stirring continued for a further 30 minutes. The resulting composition was then cooled to 125°C.

Process step (4)

The cooled composition was pumped off, filtered through a bag filter (pore size 100 µm), and cooled to room temperature. The residual solids amounted to 0.2 wt% based on the total mass of the composition before filtration.

Thus, a composition was obtained whose content of primary aromatic amines was below 0.1 wt%.

• Hydroxylzahl: 456 mg KOH/g, gemessen nach DIN 53240
• Säurezahl: 11,2 mg KOH/g, gemessen nach DIN 53402
• Aminzahl: 28 mg KOH/g, gemessen nach DIN 53176
• Viskosität: 7.800 m Pa*s bei 25°C, gemessen nach DIN 53019

The filtered composition had the following properties:

• Hydroxyl number: 456 mg KOH/g, measured according to DIN 53240
• Acid number: 11.2 mg KOH/g, measured according to DIN 53402
• Amine number: 28 mg KOH/g, measured according to DIN 53176
• Viscosity: 7,800 m Pa*s at 25°C, measured according to DIN 53019

This composition is suitable for the production of new PUR/PIR rigid foams.

Example 7:

Process step (1)

In the stainless steel reactor 1 of a plant according to 1 44.6 wt% diethylene glycol together with 2.9 wt% dibutylamine were initially charged and heated to 160 °C under reflux within 60 minutes.

At a reactor temperature between 170°C and 205°C, 42 wt% unsorted polyurethane rigid foam waste (shredded and compacted) was added over a period of 3 hours under reflux and nitrogen blanketing, and the mixture was continuously stirred until the waste was dispersed and dissolved. The column head temperature was maintained below 40°C by the cooling medium in the column jacket and dephlegmator.

The temperature was then increased to 220°C and the reaction mixture was stirred under reflux for 40 minutes.

Process step (2)

After cooling the reaction mixture to 170°C and switching from reflux to atmospheric distillation, 8.5 wt% phthalic anhydride was added. The column head temperature was maintained at 110°C by controlled temperature control of the column jacket and dephlegmator.

During the subsequent reaction, the temperature of the reaction mixture was gradually increased to 230°C depending on the column head temperature and distillate flow.

The reaction mixture was stirred for 30 minutes at a temperature of 230°C and then cooled to 190°C with stirring. When the reaction mixture temperature was in the range of 180°C to 190°C, 2 wt% maleic anhydride was added, and the mixture was stirred for a further 30 minutes and cooled to 180°C.

Process step (3)

Then 1 wt% propylene carbonate was added and stirring was continued for another 30 minutes at 180°C.

Process step (4)

The modified composition formed in process step (3) was then pumped off, filtered through a self-cleaning filter (pore size 100 µm), and cooled to room temperature. The residual solids amounted to 0.02 wt% based on the total mass of the modified composition before filtration.

Thus, a composition was obtained whose content of primary aromatic amines was below 0.1 wt% (below 1000 ppm).

• Hydroxylzahl: 405 mg KOH/g, gemessen nach DIN 53240
• Säurezahl: 0,8 mg KOH/g, gemessen nach DIN 53402
• Aminzahl: 26 mg KOH/g, gemessen nach DIN 53176
• Viskosität: 6.500 m Pa*s bei 25°C, gemessen nach DIN 53019

The composition has the following properties after filtration:

• Hydroxyl number: 405 mg KOH/g, measured according to DIN 53240
• Acid number: 0.8 mg KOH/g, measured according to DIN 53402
• Amine number: 26 mg KOH/g, measured according to DIN 53176
• Viscosity: 6,500 m Pa*s at 25°C, measured according to DIN 53019

This composition is suitable for the production of new PUR/PIR rigid foams.

QUOTES CONTAINED IN THE DESCRIPTION

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Cited patent literature

• DE 10 2009 026 898 A1 [0003]

Claims (10)

A process for obtaining polyols from polyurethane waste, comprising the steps of: (1) reacting (a) polyurethane waste with (b) one or more compounds from the group of diols having 2 to 8 carbon atoms and triols having 3 to 8 carbon atoms and (c) one or more compounds from the group of aliphatic amines and cycloaliphatic amines to form a reaction mixture, (2) reacting the reaction mixture formed in step (1) with (d) one or more compounds from the group of dicarboxylic acids and dicarboxylic anhydrides to form a composition containing one or more polyols formed from the polyurethane waste (a). Procedure according to Claim 1 , wherein step (1) comprises a reaction (a) of polyurethane waste with (b) one or more compounds from the group of diols having 2 to 8 carbon atoms and triols having 3 to 8 carbon atoms and (c) one or more compounds from the group of aliphatic amines and cycloaliphatic amines under reflux and step (2) comprises a reaction of the reaction mixture formed in step (1) with (d) one or more compounds from the group of dicarboxylic acids and dicarboxylic anhydrides with distillation of constituents of the reaction mixture having a boiling point ≤ 100 °C, preferably ≤ 110 °C, particularly preferably ≤ 120 °C. Procedure according to Claim 1 or 2 , wherein (a) polyurethane waste is used in a total amount of 30% to 75%, preferably 35% to 55%, (b) compounds from the group of diols with 2 to 8 carbon atoms and triols with 3 to 8 carbon atoms are used in a total amount of 20% to 50%, preferably 25% to 45%, (c) compounds from the group of aliphatic amines and cycloaliphatic amines are used in a total amount of 2% to 15%, preferably 2.5% to 8%, (d) compounds from the group of dicarboxylic acids and dicarboxylic anhydrides are used in a total amount of 3% to 25%, preferably 5% to 20%, particularly preferably 6% to 13%, in each case based on the total mass of the substances (a), (b), (c) and (d) as 100%. Method according to one of the Claims 1 until 3 , wherein the polyurethane waste (a) comprises a material type from the group consisting of rigid polyurethane foam, polyurethane/polyisocyanurate rigid foam, semi-rigid polyurethane foam, flexible polyurethane foam and unfoamed polyurethane, and/or the compounds (b) are selected from the group consisting of ethylene glycol, diethylene glycol, dipropylene glycol, 1,3-propane glycol, 1,2-butanediol, 1,4-butane glycol and glycerol, and/or the compounds (c) are selected from the group consisting of dibutylamine, N-ethylcyclohexylamine, dipropylenetriamine, 3,3'-diamino-N-methyldipropylamine, diethylenetriamine, ethylenediamine, hexamethylenediamine, triethylenediamine, and/or the compounds (d) are selected from the group consisting of adipic acid, succinic acid, glutaric acid, malic acid, phthalic acid, maleic acid, dihalogenated phthalic acid, tetrahalogenated phthalic acid and its anhydrides, and/or the concentration of primary aromatic amines in the composition prepared is less than 0.1%, preferably less than 0.05%, based on the total mass of the composition. Method according to one of the Claims 1 until 4 , wherein step (1) is carried out in the presence of a catalyst, wherein the catalyst is preferably selected from the group consisting of potassium 2-ethylhexanoate, potassium neodecanoate and potassium acetate. Method according to one of the Claims 1 until 5 , wherein step (2) is carried out in the presence of a catalyst, wherein the catalyst is preferably selected from the group consisting of tetraisobutyl orthotitanate, titanium(IV)(triethanolaminato)isopropoxide and tin(II) chloride. Method according to one of the Claims 1 until 6 , wherein the composition formed in step (2) contains one or more polyester polyols formed by esterification and/or transesterification of polyols formed from the polyurethane waste (a) with one or more compounds (d) from the group of dicarboxylic acids and dicarboxylic acid anhydrides. Method according to one of the Claims 1 until 7 , wherein step (1) comprises a reaction of (a) polyurethane waste with (b) one or more compounds from the group of diols having 2 to 8 carbon atoms and triols having 3 to 8 carbon atoms and (c) one or more compounds from the group of aliphatic amines and cycloaliphatic amines at temperatures in the range from 180°C to 230°C, preferably 190°C to 225°C, particularly preferably 200°C to 215°C and/or step (2) comprises a reaction of the reaction mixture formed in step (1) with (d) one or more compounds from the group of dicarboxylic acids and dicarboxylic anhydrides at a temperature in the range from 215°C to 235°C, preferably 220°C to 230°C, particularly preferably 220°C to 225°C. Method according to one of the Claims 1 until 8 , further comprising the step (3) adding one or more substances from the group consisting of - catalysts for the synthesis of polyurethane polyisocyanurates, wherein the catalyst is preferably selected from the group consisting of potassium 2-ethylhexanoate, potassium neodecanoate and potassium acetate, - plasticizers, preferably propylene carbonate - surfactants - flame retardants to the composition obtained in step (2), so that a modified composition results Method according to one of the Claims 1 until 9 , further comprising the step (4) filtering the composition obtained in step (2) or the modified composition obtained in step (3), preferably at temperatures in the range from 100°C to 150°C, particularly preferably 110°C to 130°C, wherein the pore size of the filter is preferably 50 µm to 200 µm.