DE2902509A1 - Liq. poly:ol prepn. from polyurethane and/or polyisocyanurate waste - by heating foam with diol using gp=iv metal cpd. catalyst - Google Patents

Abstract

Polyol-contg. liq. prepn. by heating opt. communited polyurethane and/or polyisocyanurate-contg. foam wastes with >=1 aliphatic diol having formula HO-R-OH, (I), (where R is linear or branched 2-20C alkylene, the main chain of which can be interrupted by 1 or more 0 atoms) to 150-220 degrees C, is catalysed by >=1 Gp. IVA metal cpd., (A), esp. >=1Ti and/or Zr cpd.. The polyol-contg. liq. prods. can be re-used directly for the prepn. of high-grade rigid foams. On using catalysts (A), the recycling polyol prods. obtd. have neutral pH. Viscosity is sufficiently low and compatibility with isocyanates, blowing agents and polyols is good. The foams botd. have improved flame-stability.

Description

Process for the preparation of polyol-containing liquids from

Polyurethane and / or polyisocyanurate wastes The invention relates to a process for the production of polyol-containing liquids from polyurethane / polyisocyanurate waste with at least one aliphatic diol of the general formula HO-R-OH, in which R a straight-chain or branched alkylene radical with 2 to about 20 carbon atoms is whose main carbon chain is interrupted by one or more oxygen atoms can be, in the presence of a catalyst at temperatures of about 150 to 220 ° C.

There are already several methods of digesting polyurethane waste known. 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 metal or alkaline earth metal oxide or hydroxide. In this process, an amine derivative is used as the polyisocyanate component the polyurethane as well as the polyether obtained. The disadvantage of this procedure is that that this is expensive and harmful amines, their handling at the high Temperatures of thermal decomposition brings considerable risk with it, used Need to become. Furthermore, form in this process two layers, so that the reaction mixture does not immediately return to the production of polyurethane foams can be used; rather, the polyol component must first be removed from the reaction mixture be separated in a complex manner.

From US-PS 3,441,616 a process for the recovery of Polyether polyols known from polyurethanes, in which the polyurethane with a strong Base from the group of alkali and alkaline earth metal oxides and hydroxides in one Wass er / Dimethyl sulfoxid-Meaium is hydrolyzed. That obtained in the hydrolysis Polyether polyol must then from the reaction mixture by means of a liquid, with the Water / dimethyl sulfoxide medium immiscible paraffinic hydrocarbon be extracted in a cumbersome manner, and the polyether polyol must then werien obtained from the extract by separating off the paraffinic hydrocarbon.

Furthermore, it is already known to waste polyurethane waste by heating with mixtures of aliphatic diols and alkanol ~ amines to form polyol-containing liquids to work up. According to DE-AS 22 38 109 this is a dialkanolamine with 1 to 8 carbon atoms are used, and the reaction takes place at temperatures of about 175 to 2500C. A similar method is from DE-OS 25 57 172 known in which the alkanolamine is a monoalkanolamine with 2 to 8 carbon atoms used and the reaction is carried out at temperatures from 150 to 2200C. In these processes, relatively long reaction times are required to achieve acceptable reaction times Amounts of catalyst required. Due to the relatively high proportion of catalyst in the so obtained polyol-containing liquid is. however the quality of this liquid produced polyurethane adversely affected. Another disadvantage is that the alkanolamines used as catalysts are toxic and at the high reaction temperature go fleetingly what a means significant environmental hazard.

Common to all of the processes mentioned is the use of low-temperature catalysts. If pure polyurethane waste is used, this leads to a basic reaction of the polyol reaction product. Because in the modern production of polyurethane foams a precisely coordinated Amount of basic amine catalysts must be added to achieve optimal foam properties to achieve, the basic substances contained in the polyol product have a disruptive effect. There the basicity of the reaction products fluctuates strongly, a precise setting of the catalyst is required difficult to do. It is therefore necessary to use a to carry out expensive and difficult neutralization of the reaction product.

It has also been shown that when digesting phosphorus and chlorine-containing polyurethane wastes present considerable difficulties in use of basic amine catalysts occur. This is expressed in the fact that in the course the reaction rate and at the same time the pH decrease sharply and the product turns dark. The catalyst will likely be used during the Reaction blocked by salt formation. After adding more basic catalyst the reaction starts again, with the same decrease after a certain time the reaction rate and the pH value can be observed. This show is probably due to the fact that the basic catalysts mentioned at the same time the elimination of phosphoric acid or hydrochloric acid from the phosphoric or accelerate chlorinated fire retardants. This reaction not only leads to Blocking of the basic catalysts, but also to acidification of the reaction product.

Experiments have shown that pH values of 2 to 3 can occur. Since there is already a lot of polyurethane foam waste containing chlorine and phosphorus Contain fire retardants and in practice always mixed foam waste need to be worked up, this is a serious disadvantage of the above Work-up procedures. The pH values of the reaction products fluctuate in such a way large area that direct use without complex post-reaction is not possible is. Due to the new fire protection regulations, there is also a further increase fire retardant-containing foams are to be expected, so that the above-described Problems will become even more pronounced in the future.

The present invention is therefore based on the object of an improved one To create a process for the production of polyol-containing liquids, in which the The disadvantages mentioned no longer occur and can be easily obtained using polyols Liquids that lead directly back to the production of high quality Rart foams are usable.

This task is thereby achieved in a method of the type mentioned at the outset solved that at least one compound of a metal of IV. Subgroup of the Periodic System of the Elements is used.

It has surprisingly been found that when using Transition metal compounds of subgroup IV have the disadvantages described above no longer occur. These catalysts continue to excellently accelerate the Transesterification reaction between aliphatic diol and polyurethane or

Polyisocyanate and result in a completely homogeneous, immediately further processable polyol-containing liquid. The main advantage of the recycled polyols produced in this way is the pH value neutrality, i.e. independent of the composition used of the foam waste, the polyol reaction product is neither acidic nor basic Properties that are responsible for irregularities in foam production are.

The viscosity of the recycled polyol produced according to the invention is sufficiently low and the compatibility with isocyanates, blowing agents, polyols Sufficiently good to use polyurethane hard foams of different density to manufacture. It is also possible by increasing the isocyanate index, i.e. at strong excess of isocyanates and the use of special catalysts, one to produce polyurethane-containing polyisocyanurate foam. The isocyanate / recycled polyol ratio can be varied within wide limits. Draw the foams obtained in this way is characterized by increased flame retardancy.

In the process according to the invention, a2s compounds of the metals of subgroup IV alcoholates (esters), halides, oxyhalides, alkali titanates, complex titanates and corresponding zirconates are used. Preferably compounds of the titanium used, with essentially the solubility of the titanium compound in diols is decisive.

Easily soluble and highly effective are monomeric or polymeric titanium butylate, Titanium ethylate and titanium methylate or higher, also mixed and complex titanates of the general formula TiR4, where R can be the same or different. Just as effective are alcoholates (esters) of the diol used in the reaction. These arise in a simple manner from titanium tetrahalides, such as titanium tetrachloride and the diol before the actual transesterification reaction taking place in the process according to the invention Since in the alcoholate or ester formation from itane tetrahalide with diols hydrogen halide arises, an at least equivalent amount of an epoxy is used to bind it, such as propylene oxide or epichlorohydrin, added.

Likewise, from alkali titanates are formed during the reaction with diols Titanium alcoholates or esters, which are used for the catalytic effectiveness are responsible. The above statements in connection with titanium compounds The same applies to Bür zirconium and hafnium compounds. Eitan compounds are preferred to zirconium or hafnium compounds because of their low price, apart from the fact that their effectiveness drops somewhat compared to titanium compounds. Zirconium compounds such as zirconium n-propoxide, zirconium n-butoxide or zirconium tetrachloride, however, they are effective catalysts.

The catalysts used in the present invention are preferred in amounts of about 0.5 to 5% based on the weight of the foam waste, used. Particularly favorable results are achieved when using around 1 to 3 % Catalyst obtained.

Compounds can be used as aliphatic diols in the process according to the invention of the general formula H0-R-OH, in which R is a straight-chain or branched alkylene radical with 2 to about 20 carbon atoms, the main carbon chain of which is through one or several oxygen atoms can be interrupted. Specific Examples of straight-chain diols are ethylene glycol, 1,4 butanediol and 1,5-pentanediol and the diols preferred according to the invention, dipropylene glycol and tripropylene glycol. Diethylene glycol and triethylene glycol are also eminently suitable for the invention Methods, however, are conventional in the polyol-containing liquids thus obtained Rigid polyurethane foams made with organosilicon wetting agents are the way to go coarser cell structure with somewhat impaired mechanical properties. As a branched aliphatic diol in the process according to the invention, for example Neopentyl glycol can be used.

Even polyols with molecular weights up to. about 5000 used , the viscosity of the reaction products naturally increasing.

The weight ratio of aliphatic diol to polyurethane waste in the method according to the invention is preferably about 3: 5 to about 5: 1 and especially about 4: 5 to about 2: 1.

The reaction is carried out at temperatures from about 150 to about 220 ° C .; preferably the reaction temperature is in the range from about 180 to about 2000 C.

By means of the method according to the invention, polyol-containing Liquids from any polyurethane waste, i. E.

from cellular (closed-cell and open-cell) and non-cellular Polyurethane waste, which are based on polyurethanes of polyether polyols and / or polyester polyols. Preferably be Polyurethanes based on polyether polyols are used. In particular, is suitable the process according to the invention for the production of polyol-containing liquids Polyurethane foam waste, whereby using rigid polyurethane foam waste particularly good results can be achieved. According to the method according to the invention can but also flexible polyurethane foams and polyisocyanurate foams as well as flame retardant-containing foams Polyurethane waste containing, for example, phosphorus, antimony, chlorine or bromine, processed into polyol-containing liquids. The invention is also suitable Excellent method for processing any technical polyurethane waste mixture, the various isocyanate building blocks, prepolymers, polyisocyanurate building blocks as well contain various polyol components and other additives such as flame retardants. Technical polyurethane waste can therefore be produced by the process according to the invention of various origins and compositions can easily be combined with polyols Process liquids which are then used again directly for polyurethane production can be.

An expedient embodiment of the method according to the invention is described in detail below: The aliphatic diol is in a reactor submitted and heated with the catalyst 50 to 2000C. Then the one to be implemented Polyurethane in solid, crushed form is metered in. The addition of the polyurethane in the form of small particles produced, for example, by grinding the advantage that the volume of the starting material is reduced and metering is made easier and the response time is shortened. The addition of the polyurethane is carried out in such a way that that the viscosity of the reaction mixture in the reactor is just low enough to to ensure complete mixing and adequate heat exchange. The reaction is over when the viscosity has dropped to a minimum or the reaction mixture is completely homogeneous and when tested by application no longer contains any visible particles in a thin layer.

The process according to the invention can be batchwise or semicontinuously and also carried out continuously by adding all components at the same time will.

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

Example 1 A with thermometer, reflux condenser, inlet for polyurethane foam powder, Inlet for nitrogen and equipped with a stirrer and heating mantle The 1 liter reactor was filled with 500 g of dipropylene glycol and 10 g of monomeric titanium butoxide loaded. After the mixture had been heated to 2000C, a screw metering device was used powdery Rigid polyurethane foam at such a rate metered in so that the mixture remained stirrable. The reaction was carried out under nitrogen carried out. After 60 minutes, all of the 500 grams were rigid polyurethane foam metered in. The reactor was then sealed and the mixture became an additional 60 Stirred for minutes at 200 ° C. The total reaction time was 120 minutes. After this Time the reaction mixture was thin and homogeneous and could in this form can be removed from the reactor. After cooling the reaction mixture was a light brown viscous homogeneous liquid is obtained. The hydroxyl number of the product was 480 mg EOH / g; the acid number was 0.9 mg K0IVg. The pH of a 10 show Solution in ethanol / acetone was 7.5.

Foaming tests: 75 g of the polyol-containing compounds obtained as described above Liquid was mixed with 2 g of a common silicone wetting agent, 2 g of a common Amine catalyst and 25 g of a conventional fluorochloromethane propellant are added and intimately mixed.

The mixture was then mixed with 100 g of crude methylenediphenyl diisocyanate added and stirred intensively for 30 seconds. After a further 30 seconds, foaming continued a. After a further 2 minutes, the foam was cured. It became a fine-pored Obtained foam with good mechanical properties.

The following examples and foaming tests were carried out accordingly Example 1 carried out unless otherwise specified.

Comparative example The comparative example was made with monoethanolamine carried out as a catalyst.

Starting substances: 500 g polyurethane 500 g dipropylene glycol 25 g Monoethanolamine (5% based on polyurethane) Reaction temperature: 2000C Addition time: 100 minutes post-reaction time: 75 minutes Total reaction time: 175 minutes Properties: dark red-brown, viscous homogeneous liquid hydroxyl number: 500 mg KOH / g acid number: 8.0 mg KOH / g pX value of a 10% solution: 4.5 foaming tests: slow reaction, long start and end times compared to using the example 1 produced polyol. Coarse-pored foam with poor mechanical properties.

Example 2 Starting substances: 500 g of polyurethane 500 g of dipropylene glycol 10 g zirconium butoxide (2% based on polyurethane) reaction temperature: 2000C addition time: 70 minutes post-reaction time: 60 minutes total reaction time: 130 minutes Properties: light brown viscous homogeneous liquid hydroxyl number: 465 mg EOH / g acid number: 1.0 mg EOH / g pH of a 10% solution: 6.9 Foaming tests: short ones Start and curing times. Fine-pored closed-cell foam with good mechanical properties Properties.

Example 3 Starting substances: 500 g of polyurethane 500 g of diethylene glycol 10 g polymeric titanium methylate reaction temperature: 180 ° C addition time: 80 min.

Post-reaction time: 80 minutes Total reaction time: 160 min.

Properties: very light-colored, viscous homogeneous liquid hydroxyl number: 545 mg KOE / g acid number: 0.9 mg KOH / g pH value of a 10% solution: 7.2 foaming tests When carried out according to the foaming test described in Example 1, results short start and curing times. Relatively coarse-pored foam with satisfactory mechanical properties.

When mixing 20 parts of the product with 80 parts of crude flethylene diphenyl diisocyanate using potassium acetate as a catalyst and appropriate amounts of one With the usual fluorochloromethane blowing agent and silicone surfactant, a polyurethane-polysocyanate foam is obtained with self-extinguishing fire behavior. The foam is relatively fine-pored and has good mechanical properties.

Example 4 Starting substances: 500 g of polyurethane 500 g of tripropylene glycol 10 g zirconium tetrachloride 10 g propylene oxide Reaction temperature: 200 ° C Addition time: 100 minutes post-reaction time: 80 minutes Total reaction time: 180 minutes Properties: light brown viscous homogeneous liquid hydroxyl number: 420 mg KOH / g acid number: 1.0 mg KOH / g pH value of a 10% solution: 7.0 Foaming tests: Fast start and hardening times. Fine-cell, closed-cell foam with good mechanical properties.

Example 5 Starting substances: 500 g of polyurethane 500 g of dipropylene glycol 15 g of titrant tetrachloride 10 g of epichlorohydrin Reaction temperature: 1800C Addition time: 80 minutes post-reaction time: 80 minutes total reaction time: 160 minutes Properties: light brown viscous liquid hydroxyl number: 470 mg KOH / g acid number: 1.5 mg KOH / g pH of a 10% solution: 6.8 Foaming tests at formulation In accordance with the foaming test in Example 1, the starting and curing times are good. Fine-pored foam with good mechanical properties.

With a product-isocyanate mixing ratio (weight) of 20 : 80 a foam with good mechanical properties is obtained. The foam is self-extinguishing.

Claims (8)

1) Dr. Gunter Bauer, IZrahenfeldstr, 18, 7080 Aalen 15 2) Johannes Apprich, Langerstr. 86, 7080 Aalen 3) Ludwig Köble, Eichklingenstr. 2, 7081 Abtsgmiind Claims 1. A method for producing polyol-containing liquids from polyurethane and / or polyisocyanurate-containing foam waste by heating given salts crushed foam waste with at least one aliphatic diol of the general Formula HO-R-OH, in which R is a straight-chain or branched alkylene radical with 2 to is about 20 carbon atoms, the main chain of which is through one or more oxygen atoms can be interrupted in the presence of a catalyst to temperatures of 150 up to about 2200C, in that the catalyst is at least a compound of a metal of subgroup IV of the Periodic Table of the Elements begins. 2. The method according to claim 1, characterized in that g e k e n n z e i c hn e t, that at least one compound of titanium and / or zirconium is used as the catalyst. 3. The method according to claim 1 and / or 2 characterized g e k e n nz e i c h n e t that a compound of a metal of the IV. subgroup of the periodic System of the elements at least one alcoholate and / or at least one halide and / or at least one other compound soluble in aliphatic diols begins. 4. The method according to any one of claims 1 to 3, characterized g e k e n n z ei c h n e t that the catalyst used is titanium methylate, titanium butylate and / or titanium tetrachloride begins. 5. The method according to any one of claims 1 to 4, characterized g e k e n n z e i c h n e t that about 0.5 to 5%, preferably 1 to 3 04 of the catalyst, based on the weight of the foam waste. 6. The method according to claim 1, characterized in that g e k e n n z e i c hn e t, that the aliphatic diol is at least one oligomeric ethylene glycol and / or Propylene glycol is used. 7. The method according to claim 6, characterized in that g e k e n n z e i c hn e t, that di- and / or triethylene glycol and / or di- and / or tripropylene glycol are used will. 8. The method according to claim 1, 6 or 7, characterized in that g e k e n nz e i c h n e t that the aliphatic diol and the polyure than- and / or polyisocyanuratha waste foam in a weight ratio of about 3: 5 to about 5: 1, preferably from about 4: 5 to about 2: 1 begins.