EP0000948A1 - Process for the preparation of polyol containing liquids from polyurethane wastes - Google Patents

Abstract

1. Method for the manufacture of polyhydric alcohol containing fluids from polyurethane scrap by heating of optionally reduced-size polyurethane scrap with at least one glycol in the presence of at least one metal of the first or of the second main groups of the periodic system of elements and/or at least one strongly basic compound of a metal of the first or second main group of the periodic system of elements as catalyst at temperatures of approximately 150 to 220 degrees C, characterised in that dipropylene glycol and/or tripropylene glycol are used as the glycol.

Description

The invention relates to a process for producing polyol-containing liquids from polyurethane wastes by heating optionally comminuted polyurethane wastes with at least one glycol in the presence of at least one metal of the first or second main group of the Periodic Table of the Elements and / or at least one strongly basic compound of a metal of the first or second Main group of the Periodic Table of the Elements at temperatures from about 150 to about 220 ° C.

A method of the aforementioned type is known from the paper from "Chemisches Zentralblatt", 1962, p.6230, in which DE-AS 11 10 405 is discussed. According to DE-AS 11 10 405, polyurethane foams are broken down at temperatures of 175 to 220 ° C with glycol and basic compounds such as KOH. In the DE-AS 11 10 405 on which the aforementioned report is based, only glycol or ethylene glycol is mentioned (example 1 of DE-AS 11 10 405; ethylene glycol; examples 2 and 3: glycol). The glycol mentioned in Examples 2 and 3 can also be taken from the overall context of DE-AS 11 10 405 only as the simplest and most common glycol, namely ethylene glycol. The disadvantage of this process is that only non-homogeneous products are obtained which have to be separated, cleaned and chemically treated before further processing into polyurethane foams.

US Pat. No. 3,404,103 describes the thermal decomposition of polyether polyurethanes in the presence of at least one amine and at least one alkali or alkaline earth metal oxide or hydroxide. An amine derivative of the polyisocyanate component of the polyurethane and of the polyether is obtained in this process. A disadvantage of this process is that expensive and health-damaging amines, the handling of which at the high temperatures of the thermal decomposition entail considerable dangers, must be used. Furthermore, two layers are formed in this process, so that the reaction mixture does not return immediately Manufacture of polyurethane foams can be used; rather, the polyol component must first be separated from the reaction mixture in a complex manner.

A process for the recovery of polyether polyols from polyurethanes is known from US Pat. No. 3,441,616, in which the polyurethane is hydrolyzed with a strong base from the group of alkali and alkaline earth metal oxides and hydroxides in a water / dimethyl sulfoxide medium. The polyether polyol obtained in the hydrolysis must not miscible paraffinic hydrocarbon are extracted in complicated manner from the reaction mixture by means of a liquid, with the water / dimethylsulfoxide medium then, and the polyether polyol must then removed from the extract by separating the ^p araffi- African hydrocarbon are recovered .

Furthermore, it is already known to process polyurethane waste by heating with mixtures of aliphatic diols and alkanolamines to give polyol-containing liquids. According to DE-AS 22 38 109, a dialkanolamine with 1 to 8 carbon atoms is used for this, and the reaction is carried out at temperatures of about 175 to 250 ° C. A similar process is known from DE-OS 25 57 172, in which a monoalkanolamine having 2 to 8 carbon atoms is used as the alkanolamine and the reaction is carried out at temperatures of 150 to 220 ° C. This process requires relatively large amounts of catalyst to achieve acceptable reaction times. However, the quality of the polyurethane produced from this liquid is adversely affected by the relatively high proportion of catalyst in the polyol-containing liquid thus obtained. Another disadvantage is that the alkanolamines used as catalysts are toxic and volatile at the high reaction temperature, which means a considerable environmental hazard.

Finally, it is known from DE-OS 25 16 863 to separate polyurethane waste by heating together with aliphatic diols in which the alkylene radical separating the two hydroxyl radicals is branched, i.e. at least one carbon atom of the alkylene chain must carry a short-chain alkyl radical to convert into homogeneous polyol mixtures. A catalyst is not added in this reaction. A disadvantage of this method is the uneconomically long reaction time and the formation of by-products caused by the long reaction time.

The present invention is based on the object of an improved process for the production of polyols To create liquids from polyurethane waste, which does not have the disadvantages of the known methods and leads in a simple manner to polyol-containing liquids which can be used directly for the production of high quality polyurethanes.

This object is achieved in a process of the type mentioned at the outset by using dipropylene glycol and / or tripropylene glycol as the glycol.

• Das im erfindungsgemäßen Verfahren verwendete System aus Di- und Tripropylenglykol mit basischen Alkali- und/oder Erdalkalimetallen und/oder -verbindungen führt gegenüber den beiden vorgenannten bekannten Verfahren zu wesentlich höheren Reaktionsgeschwindigkeiten, wobei unter denselben Reaktionsbedingungen deutliche Unterschiede in der Auflösegeschwindigkeit auftreten. Während beispielsweise bei Verwendung von 1% Natriumhydroxyd gemäß vorliegender Anmeldung eine Reaktionszeit von etwa 1,5 Stunden benötigt wird, werden bei Verwendung von 5% Monoäthanolamin gemäß der DE-OS 25 57 152 etwa 3 Stunden benötigt, um denselben Umsetzungsgrad zu erhalten. Bei Durchführung der Umsetzung ohne Katalysator gemäß der DE-OS 25 16 863 dauert die Reaktion etwa 10 bis 12 Stunden. Gegenüber dem mit einer kurzen Reaktionszeit auskommenden erfindungsgemäßen Verfahren sind die beiden bekannten, wesentlich längere Reaktionszeiten benötigenden Verfahren unwirtschaftlich.

The advantages of the method according to the invention over the methods known from DE-OS 25 16 683 and DE-OS 25 57 712, which are also said to lead to homogeneous polyol-containing liquids, are set out below:

• The system of di- and tripropylene glycol with basic alkali and / or alkaline earth metals and / or compounds used in the process according to the invention leads to significantly higher reaction rates than the two aforementioned known processes, with clear differences in the dissolution rate occurring under the same reaction conditions. For example, while a reaction time of about 1.5 hours is required when using 1% sodium hydroxide according to the present application, when using 5% monoethanolamine according to DE-OS 25 57 152 it takes about 3 hours to obtain the same degree of conversion. When the reaction is carried out without a catalyst according to DE-OS 25 16 863, the reaction takes about 10 to 12 hours. Compared to the method according to the invention, which manages with a short reaction time, the two known methods, which require considerably longer reaction times, are uneconomical.

The process according to the invention is further distinguished from the process known from DE-OS 25 16 863, which works without a catalyst, in that the reaction proceeds more completely. It is true that homogeneous reaction product mixtures can also be obtained by the known process; however, this is not the only criterion for the usability of the reaction product. It is essential for this that the transesterification that takes place during the reaction takes place completely, since only then is the resulting liquid, homogeneous reaction product very easy to mix with the isocyanate used for the production of polyurethane and the blowing agent. By gel permeation chromatography measurements it was found that the ease of mixing increases with the lower molecular weight of the reaction product, which in turn is directly related to the conversion obtained in the reaction.

In reactions without a catalyst according to DE-OS 25 16 863, homogeneous reaction product mixtures are obtained; however, these are not low-molecular enough to ensure the required ease of mixing with the other components required for the production of polyurethane. The use of reaction product mixtures which have not been completely converted, as are obtained according to DE-OS 25 16 863, leads to the mixture clumping together in the production of polyurethane, ie these reaction product mixtures are unusable in practice. - With a correspondingly long reaction time and high temperatures, it is also possible to achieve complete conversion by the process known from DE-OS 25 16 863; however, as experiments have shown, this is with reaction times of up to 24 hours and a darkness caused by side reactions coloring of the product. It is not possible to produce high-quality foams with such reaction product mixtures.

The process according to the invention is initially distinguished from the process known from DE-OS 25 57 172 by the approximately twice as high reaction rate; the method according to the invention is thus far more economical than the known method. It should also be emphasized that much smaller amounts of a cheaper catalyst are necessary in the process according to the invention, nevertheless higher reaction rates being achieved. The amines used as a catalyst in the process according to DE-OS 25 57 172 and subsequently contained in the reaction mixture react disadvantageously in the manufacture of polyurethane with isocyanates to give urea structures which are undesirable because they adversely affect the mechanical properties of hard polyurethanes. In addition, the volatility of the amines used in the known process has a disadvantageous effect: at reaction temperatures of around 200 ° C., part of the toxic and environmentally hazardous amines escapes from the reaction vessel unless expensive devices prevent this.

Furthermore, comparative tests have shown that the acid number of polyol reaction product mixtures prepared in accordance with DE-OS 25 57 172 is far higher than the acid number of reaction product mixtures prepared according to the invention. This effect occurs in particular when falling polyurethane phosphorus compounds are contained in the _b to be processed A. Such compounds are, if one processes mixed wastes from different productions, always because of the contents of flame retardant polyurethanes contain. Comparative tests have shown that the products obtained according to DE-OS 25 57 172 can have acid numbers of up to 30 mg / KOH / g, while the acid numbers of products obtained according to the invention did not exceed 2 mg KOH / g. - The reaction product mixtures obtained according to DE-OS 25 16 863 also have high acid numbers. These are due to the long reaction times required at high temperatures. The reaction products prepared according to the invention are therefore much better suited for reuse in the manufacture of polyurethane as intended, since high and fluctuating acid numbers block the polyurethane formation reaction.

The above statements show that the reaction product mixtures obtained by the known processes are not directly reusable for the production of polyurethane. At least beforehand, it has to be carried out in a complex and complicated post-reaction, e.g. with epoxides, the acid numbers are corrected accordingly. Only the process according to the invention, which uses di- and / or tripropylene glycol together with an (earth) alkali metal and / or a strongly basic compound of such a metal, guarantees a uniform acid number of the reaction product mixture between 0 and 1 mg KOH / g and thus direct use of the polyol mixture thus obtained for the production of polyurethane.

Surprisingly, the catalysts used according to the invention are soluble in the reaction mixture at the reaction temperature, with no phase separation, precipitation or similar disruptive effects occurring after the reaction has ended.

According to the process of the invention, a completely homogeneous, moderately viscous and, in terms of its chemical properties, excellent for production in particular receive suitable polyol component from rigid polyurethane foams.

In addition to the strongly reaction-accelerating effect of the catalysts used according to the invention, there is a further significant advantage that, in contrast to the known alkanolamines required in considerably larger amounts, there is no significant additional increase in the hydroxyl number or the functionality of the polyol mixture and in particular the acid number of the polyol-containing liquid obtained is substantially lower (in the range from 0 to 1) than when using alkanolamine catalysts and, moreover, the acid number can be kept constant by the process according to the invention. A major disadvantage of the reaction catalyzed with alkanolamines is that products with very high acid numbers (in the range from 10 to 20) are formed even at catalyst concentrations of over 5%. The consequence of these high acid numbers is that large amounts of basic accelerators have to be added in the subsequent customary foaming of the polyol-containing liquid thus obtained to give polyurethane foams in order to obtain useful reaction times. Furthermore, given the considerably fluctuating high acid numbers of the polyol-containing liquids produced with alkanolamine catalysts, a uniform and precisely controllable start time in the foaming process is hardly possible. In addition, the large quantities of basic accelerators required increase the price of the product and, due to their presence in the foam, impair its quality.

When using the catalysts according to the invention, these disadvantages do not occur. On the contrary, smaller amounts of accelerator are required for the foaming process than for Use of customary commercially available polyol components in order to achieve the same start and curing times in the foaming process.

Furthermore, the catalysts used according to the invention are non-toxic and also non-volatile at the reaction temperature, so that no environmental damage can occur and the process can be carried out without problems.

In the process according to the invention, the strongly basic compounds of metals of the first or second main group of the periodic system of the elements are preferably their oxides, such as lithium oxide, sodium oxide and magnesium oxide, hydroxides, such as sodium hydroxide, potassium hydroxide and calcium hydroxide, alcoholates, such as sodium methylate, potassium ethylate and magnesium ethylate, Phosphates, such as trisodium phosphate and / or acetates, such as sodium acetate and potassium acetate, are used. In addition to the preferred acetates, other basic alkali or alkaline earth salts of carboxylic acids can also be used, for example the alkali and alkaline earth formates. Carbonates, such as sodium carbonate, can also be used as catalysts in the process according to the invention.

Lithium, sodium, potassium, magnesium and / or calcium and / or at least one strongly basic compound of these metals are preferably used as basic catalysts, sodium and its compounds being particularly preferred on the basis of the particularly advantageous results obtained therewith. Among the sodium compounds, sodium hydroxide and sodium acetate are preferably used.

The catalysts used according to the invention are advantageously used in amounts of about 0.1 to about 10%, based on the weight of the polyurethane waste used. Surprisingly, it has been found that if a larger amount of catalyst is used, the reaction can be carried out effectively at lower temperatures, for example at 160 ° C. Carrying out the reaction at relatively low temperatures has the advantage that the polyol-containing liquids thus produced are only weakly colored.

0.5 to 5% catalyst, based on the weight of the polyurethane waste, is preferably used. If one works in the range of 0.5 to 2% of catalyst which is likewise preferred within this range, reaction temperatures in the range of 190 to 210 ° C. are sufficient so that these are preferred in combination with the amount of catalyst of 0.5 to 2%. On the other hand, if one works with higher amounts of catalyst in the range of 2 to 5%, reaction temperatures in the range of 160 to 190 ° C are sufficient and preferred.

The weight ratio of aliphatic diol to the polyurethane waste in the process according to the invention is advantageously from about 3: 5 to about 5: 1 and preferably from about 4: 5 to about 2: 1. The process according to the invention can be used to produce polyol-containing liquids from any polyurethane waste, ie from cellular (closed-cell and open-cell) and non-cellular polyurethane waste, which may be polyurethanes based on polyether polyols and / or polyester polyols. Polyurethanes based on polyether polyols are preferably used. The process according to the invention is particularly suitable for producing polyol-containing liquids from polyurethane foam wastes, with particularly good results being achieved using polyurethane foam wastes. According to the method of the invention, however also flexible polyurethane foams and polyisocyanurate foams and flame retardant-containing polyurethane wastes, which contain, for example, phosphorus, antimony, chlorine or bromine, are processed to give polyol-containing liquids. The process according to the invention is furthermore excellently suitable for processing any technical polyurethane waste mixtures which contain various isocyanate building blocks, prepolymers, polyisocanurate building blocks and various polyol components and other additives, such as flame retardants. According to the invention. Processes can therefore be processed jointly into technical polyurethane wastes of various origins and compositions without problems to form polyol-containing liquids, which can then be used again directly for the production of polyurethane.

• Das aliphatische Diol wird in einem Reaktor vorgelegt und auf 50 bis 200°C erhitzt. Das erwärmte Diol wird dann auf einmal oder portionsweise mit dem erfindungsgemäß verwendeten basischen Katalysator versetzt. Anschließend wird das umzusetzende Polyurethan in fester, zerkleinerter Form zudosiert. Der Zusatz des Polyurethans in Form kleiner Teilchen, die beispielsweise durch Vermahlen erzeugt werden hat den Vorteil, daß das Volumen des Ausgangsmaterials verringert, die Zudosierung erleichtert und die Reaktionszeit verkürzt wird. Die Zudosierung des Polyurethans wird so vorgenommen, daß die Viskosität des Reaktionsgemisches im Reaktor gerade niedrig genug ist, um eine vollständige Durchmischung und einen ausreichenden Wärmeaustausch zu gewährleisten. Die Reaktion ist dann beendet, wenn die Viskosität auf ein Minimum abgesunken ist bzw. das Rea-ktionsgemisch vollständig homogen ist und bei der Prüfung durch Auftragen in dünner Schicht keine sichtbaren festen Partikel mehr enthält.

An expedient embodiment of the method according to the invention is described in detail below:

• The aliphatic diol is placed in a reactor and heated to 50 to 200 ° C. The heated diol is then added all at once or in portions with the basic catalyst used according to the invention. The polyurethane to be converted is then metered in in solid, comminuted form. The addition of the polyurethane in the form of small particles, which are produced, for example, by grinding, has the advantage that the volume of the starting material is reduced, metering is made easier and the reaction time is shortened. The polyurethane is metered in such that the viscosity of the reaction mixture in the reactor is just low enough to ensure thorough mixing and sufficient heat exchange. The reaction is complete when the viscosity has dropped to a minimum or the reaction mixture is completely homogeneous and no longer contains any visible solid particles when tested by applying it in a thin layer.

When the reaction is carried out, volatile constituents distill off. These contain part of the diol used, water, the amine used as a basic accelerator for the production of polyurethane and, when polyurethane foams are worked up, the blowing agent used for foaming. This mixture can be worked up, and the recovered diol can be fed back into the reactor. The recovered amine and the blowing agent can be used again for the production of polyurethane.

The process according to the invention can be carried out batchwise, semi-continuously and also continuously by simultaneously adding all components.

• Die unter Verwendung der erfindungsgemäßen Katalysatoren ablaufenden Reaktionen unterscheiden sich grundsätzlich von den bei der Amin-katalysierten Umsetzung ablaufenden Reaktionen. Während im letzteren Fall das an der Urethangruppierung des Polyurethans angreifende Agens das Amin selbst ist, muß im ersteren Fall von folgendem Reaktionsablauf, der nachstehend am Beispiel von Natriumhydroxid dargestellt wird, ausgegangen werden: Wenn Natriumhydroxid in einem Glykol gelöst wird, bildet sich folgendes Gleichgewicht aus:
  

The reactions taking place in the process according to the invention are compared below with the reactions taking place in the known amine-catalyzed reaction:

• The reactions taking place using the catalysts according to the invention differ fundamentally from the reactions taking place in the amine-catalyzed reaction. While in the latter case the agent attacking the urethane grouping of the polyurethane is the amine itself, in the former case the following reaction sequence, which is illustrated below using the example of sodium hydroxide, must be assumed: When sodium hydroxide is dissolved in a glycol, the following equilibrium is formed :
  

The balance, which was initially shifted far to the left, is shifted to the right by the excess of diol used and by the removal of the water due to the high reaction temperature. It can therefore be assumed that both the hydroxyl anion and the alcoholate anion act as catalytically active particles which attack the urethane group. However, due to the higher nucleophilicity of the alcoholate anion, its attack on the urethane grouping is facilitated. The same effect is achieved if the corresponding metal or an appropriate alcoholate is used instead of an alkali metal or alkaline earth metal hydroxide. The same applies to basic alkali or alkaline earth salts of weak acids. These salts hydrolyze under the given conditions and form hydroxy anions, which trigger the same catalytic process.

Das neu gebildete Alkoholatianion tritt erneut in die Reaktion mit einer Urethangruppierung ein.The further course of the reaction can be formulated as follows:

The newly formed alcohol anion re-enters the reaction with a urethane group.

The reaction with hydroxyl anions proceeds accordingly, although other secondary reactions can be expected:

In accordance with the above scheme, it was demonstrated that CO ₂ is formed during the reaction.

The better effectiveness and the much lower required concentrations of the catalysts used according to the invention are presumably based firstly on their higher basicity or nucleophilicity and secondly on the constant re-formation of the active catalyst particles.

In contrast to the catalysis according to the invention, in the known amine-catalyzed reaction the catalyst is consumed by transamidation with formation of urea during the reaction according to the following scheme:

This should be the reason why the amine-catalyzed reaction requires significantly higher amounts of catalyst than in the reaction according to the invention. Urea groups are also detrimental to the quality of polyurethane foams.

The particularly pronounced activity of sodium and the sodium compounds in the novel process over other alkali and alkaline earth metals and their compounds is probably due to the fact that sodium ions can form ^p pierung in the transition state in the attack on the Urethangru more suitable complexes or Kontaktionenparen.

Generally speaking, according to the invention, all those basic substances can be used as catalysts which form hydroxyl anions or alcoholate anions in the presence of the aliphatic diols used according to the invention.

The examples illustrate the invention. All examples were carried out with technical polyurethane powder mixtures.

example 1

• 500 g Polyurethan
• 500 g Dipropylenglykol
• 5 g Natriumhydroxid (1 %, bezogen auf Polyurethan)

Starting substances:

• 500 g polyurethane
• 500 g dipropylene glycol
• 5 g sodium hydroxide (1%, based on polyurethane)

• Reaction temperature: 200 ° C
• Addition time: 35 minutes
• Post-reaction time: 35 minutes
• Total response time: 70 minutes
• Properties: dark brown viscous homogeneous liquid hydroxyl number: 0.2 mg KOH / g
• Acid number: 0.2 mg KOH / g
• pH of a 10% solution: 9.5.

Foaming tests:

75 g of the polyol-containing liquid obtained as described above were mixed with 2 g of a conventional silicone wetting agent, 2 g of a conventional amine catalyst and 25 g of a conventional fluorochloromethane blowing agent and mixed intimately. The mixture was then mixed with 100 g of methylene diphenyl diisocyanate and stirred intensively for 30 seconds. Foaming starts after a further 30 seconds. After a further 2 minutes the foam had hardened. If the amount of catalyst is reduced by a third of the usual amount, useful reaction times are obtained. Fine-pored closed-cell foam with excellent mechanical properties, in particular high pressure and abrasion resistance.

The following examples and foaming tests were carried out in accordance with Example 1.

Comparative example

• 500 g Polyurethan
• 500 g Diäthylenglykol
• 25 g Monoäthanolamin (5 %, bezogen auf Polyurethan)

Starting substances:

• 500 g polyurethane
• 500 g diethylene glycol
• 25 g monoethanolamine (5%, based on polyurethane)

• Reaction temperature 200 ° C
• Addition time 100 minutes
• Post-reaction time: 75 minutes
• Total response time: 175 minutes
• Properties: reddish brown, relatively low viscous homogeneous liquid
• Hydroxyl number: 580 mg KOH / g
• Acid number: 10.5 mg KOH / g
• pH of a 10% solution: 3.6

Foaming tests:

Slow reaction, long start and curing times compared to the use of the polyol produced according to Example 1. Very large-pored foam with poor mechanical properties.

Example 2

• 500 g Polyurethan
• 500 g Dipropylenglykol
• 5 g Natriumacetat (1 %, bezogen auf Polyurethan)

Starting substances:

• 500 g polyurethane
• 500 g dipropylene glycol
• 5 g sodium acetate (1%, based on polyurethane)

• Reaction temperature: 200 ° C
• Addition time: 40 minutes
• Post-reaction time: 45 minutes
• Total response time: 95 minutes
• Properties: dark brown viscous homogeneous liquid hydroxyl number: 510 mg KOH / g
• Acid number: 0 1 mg KOH / g
• pH of a 10% solution: 10.0.

Foaming tests:

Very short start-up and curing times. To achieve useful reaction times, the amount of catalyst must be reduced to a third. Fine-pored closed-cell foam with excellent mechanical properties.

Example 3

• 500 g Polyurethan
• 800 g Dipropylenglykol
• 5 g Kaliumhydroxid

Starting substances:

• 500 g polyurethane
• 800 g dipropylene glycol
• 5 g of potassium hydroxide

• Reaction temperature: 190 ° C
• Addition time: 80 minutes
• Post-reaction time: ⁸⁰ minutes
• Total response time: 160 minutes
• Properties: dark brown, relatively low viscous, homogeneous liquid
• Hydroxyl number: 558 mg KOH / g
• Acid number: 1.0 mg KOH / g
• pH of a 10% solution: 7.5

Foaming tests:

Favorable start and curing times. Fine-pored closed-cell foam with excellent mechanical properties

Example 4

• 500 g Polyurethan
• 500 g Dipropylenglykol
• 10 g Lithiumhydroxydhydrat

Starting substances:

• 500 g polyurethane
• 500 g dipropylene glycol
• 10 g of lithium hydroxide hydrate

• Reaction temperature: 200 ° C
• Train time: 60 minutes
• Post-reaction time: 40 minutes
• Total response time: 100 minutes
• Properties: Dark brown viscous homogeneous liquid
• Hydroxyl number: 490 mg KOH / g
• Acid number: 0.8 mg KOH / g
• pH of a 10% solution: 8.0.

Foaming tests:

Short start-up and curing times. Fine-pored foam with good mechanical properties.

Example 5

• 500 g Polyurethan
• 500 g Dipropylenglykol
• 10 g Calciumhydroxid

Starting substances:

• 500 g polyurethane
• 500 g dipropylene glycol
• 10 g calcium hydroxide

• Reaction temperature: 210 ° C
• Addition time: 60 minutes
• Post-reaction time: 50 minutes
• Total response time: 110 minutes
• Properties: Dark brown viscous homogeneous liquid
• Hydroxyl number: 478 mg gOH / g
• Acid number: 0.5 mg KOH / g
• pH of a 10% solution: 9.0

Foaming tests:

Favorable start and curing times. Fine-pored foam with good mechanical properties.

Example 6

• 500 g Polyurethan
• 500 g Dipropylenglykol
• 10 g Trikaliumphosphathydrat

Starting substances:

• 500 g polyurethane
• 500 g dipropylene glycol
• 10 g tripotassium phosphate hydrate

• Reaction temperature: 200 ° C
• Addition time: 80 minutes
• Post-reaction time: 60 minutes
• Total response time: 140 minutes
• Properties: Dark brown, highly viscous liquid. A small amount of a solid crystalline residue can be filtered off while hot
• Hydroxyl number: 505 mgKOH / g
• Acid number: 2.1 mg KOH / g
• pH of a 10% solution: 7.0

Foaming tests:

Satisfactory start and curing times. Fine-pored foam with good mechanical properties.

Example 7

• 500 g Polyurethan
• 500 g Dipropylenglykol
• 10 g Trinatriumphosphat

Starting substances:

• 500 g polyurethane
• 500 g dipropylene glycol
• 10 g trisodium phosphate

• Reaction temperature: 200 C.
• Addition time: 70 minutes
• Post-reaction time: 60 minutes
• Total response time: 130 minutes
• Properties: Dark brown, highly viscous liquid. A small amount of a solid crystalline residue can be filtered off while hot.
• Hydroxyl number: 485 mg KOH / g
• Acid number: 2.0 mg KOH / g
• pH of a 10% solution: 7.2

Foaming tests:

Satisfactory start and curing times. Fine-pored foam with good mechanical properties.

Example 8

• 500 g Polyurethan
• 800 g Dipropylenglykol
• 3 g metallisches Natrium

Starting substances:

• 500 g polyurethane
• 800 g dipropylene glycol
• 3 g of metallic sodium

• Reaktionstemperatur: 200°C
• Zugabezeit: 30 Minuten
• Nachreaktionszeit: 25 Minuten
• Gesamtreaktionszeit: 55 Minuten
• Eigenschaften: Dunkelbraune, relativ gering viskose homogene Flüssigkeit
• Hydroxylzahl: 550 mg,KOH/g
• Säurezahl: 0 mg KOH/g
• pH-Wert einer 10%igen Lösung: 10,4

The sodium is added to the not yet heated dipropylene glycol in the form of small pieces at once. After warming to 50 ° C, the sodium completely dissolves with vigorous evolution of hydrogen. The mixture is then heated to 200 ° C and proceed as described in Example 1:

• Reaction temperature: 200 ° C
• Addition time: 30 minutes
• Post-reaction time: 25 minutes
• Total response time: 55 minutes
• Properties: Dark brown, relatively low viscous homogeneous liquid
• Hydroxyl number: 550 mg, KOH / g
• Acid number: 0 mg KOH / g
• pH of a 10% solution: 10.4

Foaming tests:

Very short start-up and curing times. Fine-pored, closed-cell foam with high pressure and abrasion resistance.

Example 9

• 500 g Polyurethan
• 500 g Tripropylenglykol
• 5 g Natrlumoxid

Starting substances:

• 500 g polyurethane
• 500 g tripropylene glycol
• 5 g sodium oxide

• Reaction temperature 200 ° C
• Addition time: 40 minutes
• Post-reaction time: 30 minutes
• Total response time: 70 minutes
• Properties: Dark brown, highly viscous, homogeneous liquid
• Hydroxyl number: 440 mg KOH / g
• Acid number: 0.1 mg KOH / g
• pH of a 10% solution: 10.0

Foaming tests:

Very short start-up and curing times. Fine-pored closed-cell foam with good mechanical properties.

Example 10

• 500 g Polyurethan
• 800 g Dipropylenglykol
• 5 g Natriummethylat

Starting substances:

• 500 g polyurethane
• 800 g dipropylene glycol
• 5 g sodium methylate

• Reaction temperature: 200 ° C
• Addition time: 25 minutes
• Post-reaction time: 30 minutes
• Total response time: 55 minutes
• Properties: Dark brown, viscous, homogeneous liquid
• Hydroxyl number: 585 mg KOH / g
• Acid number: 0.4 mg KOH / g
• pH of a 10% solution: 9.3

Foaming tests:

Very short start-up and curing times. Fine-pored closed-cell foam with good mechanical properties.

Claims (6)

1. A process for producing polyol-containing liquids from polyurethane waste by heating optionally comminuted polyurethane waste with at least one glycol in the presence of at least one metal of the first or second main group of the Periodic Table of the Elements and / or at least one strongly basic compound of a metal of the first or second main group of Periodic system of the elements at temperatures of about 150 to about 220 ° C, characterized in that for the production of homogeneous polyol-containing liquids which can be directly processed into rigid polyurethane foams, dipropylene glycol and / or tripropylene glycol is used. 2. The method according to claim 1, characterized in that one uses an oxide, hydroxide, alcoholate, phosphate and / or acetate as the strongly basic compound of a metal of the first or second main group of the periodic system of the elements. 3. The method according to claim 1 or 2, characterized in that lithium, sodium, potassium, magnesium and / or calcium and / or at least one strongly basic compound of these metals is used as the basic catalyst. 4. The method according to any one of claims 1 to 3, characterized in that sodium hydroxide or sodium acetate is used as the basic catalyst. 5. The method according to any one of claims 1 to 4, characterized in that about 0.1 to about 10%, preferably about 0.5 to about 5% catalyst, based on the weight of the polyurethane waste, is used. 6. The method according to claim 1, characterized in that one uses the aliphatic diol and the polyurethane waste in a weight ratio of about 3: 5 to about 5: 1, preferably from about 4: 5 to about 2: 1.