DE19512778C1 - Prodn. of isocyanate-reactive poly:ol dispersion from waste polyurethane - Google Patents

Abstract

The prodn. of isocyanate-reactive polyol dispersions (I)from waste polyurethane (PU) comprises decomposition of the PU at 140-250 deg C with cyclic anhydrides, i.e. succinic, glutaric, malic, phthalic, dihalo-phthalic or tetrahalo-phthalic anhydride, or with Diels-Alder adducts of maleic anhydride and/or the diacids corresp. to these anhydrides and/or derivs. thereof (II), in presence of polyether-ols (III) with a mol. wt. of 500-6000 and an OH functionality of 2-5, which are subjected to a grafting reaction with carbonyl gp.-contg. unsatd. monomers (IV) before or during the decomposition reaction.

Description

The present invention relates to a method for producing isocy anat-reactive polyol dispersions and their use in the manufacture development of new polyurethanes.

It is known to use polyurethane (PUR) by chemical conversion Water (hydrolysis), amines (aminolysis) or alcohols (alcoholysis) in to transfer isocyanate-reactive, liquid products. In particular the Al Koholysis has become a technically feasible method for this raw material recycling of polyurethanes developed.

The alcoholysis of PUR is based on an equilibrium reaction in which cher for the cleavage of the urethane groups on stoichiometric amounts Hydroxyl groups in the form of diols are required. A together The known methods for the alcoholysis of PUR can be found in Kunststoff 81 (1991), pp. 301-305.

The diols are not used in excess in the alcoholysis of PUR sets, the alcoholysis reaction remains on the level of higher molecular weight Fragments stand. The highly viscous and inhomogeneous NEN products are not suitable for the production of PUR using conventional Processing devices. The known alcoholysis process Ren polyols are particularly disadvantageous in that they are high Have hydroxyl equivalents, which makes their application to Her position of hard PUR products is limited.

All known methods are further disadvantageous in that as a secondary products in not inconsiderable quantities of aromatic amines those that are usually classified as toxic and must be declared.

Since recyclate raw materials to be classified in this way are difficult to handle, Attempts have been made to use aromatic additives with amine-reactive additives To bind amines and reduce them to the lowest possible level. Process for deaminating such recycled polyols with various Additives during or after the alcoholysis reaction are for example  in DE-B 41 16 700, DE-A 42 15 014 and DE-A 42 34 335. Around to achieve a tolerable minimum content of aromatic amines, however, significant amounts of deaminating reagents are required which both increase costs and impair quality visibly affect the use of alcoholysis polyols. The possible Practical application of PUR recycling through alcohol This limits them considerably.

The present invention is therefore based on the object of a method ren for the production of stable isocyanate-reactive polyol dispersions through chemical degradation of polyurethane waste len, in which the aforementioned disadvantages of alcoholysis do not occur, and in which in particular recycled polyols are obtained which have only one very small amount of aromatic amines and unreacted Gly kolen contain, so that the recycled polyols very much Have lower hydroxyl numbers than previously alcoholic polyols.

This object is achieved by a method according to An spell 1 solved. Advantageous embodiments of the invention Procedures are specified in the subclaims.

The invention also relates to the use of the invented Process according to the invention produced polyol dispersions for the manufacture development of new polyurethanes, especially flexible polyurethane foam fabrics.  

According to the invention, it has surprisingly been found that polyurethane ne with the cyclic dicarboxylic acid anhydrides and / or cyclic dicar mentioned in claim 1 dicarboxylic acids and / or their derivatives that form bonic anhydrides then form stable, finely dispersed, liquid polyol products when the order Settlement is carried out in the presence of polyetherols before or during the degradation reaction with carbon-unsaturated, carbo nyl group-containing monomers of a radical grafting reaction be subjected. Products are obtained whose hydroxylä equivalents in the area of the polyetherols used for the degradation reaction lie. Thus, according to the invention, chemi The breakdown of polyurethanes to produce raw materials that are not only used for Manufacture harder, but also softer and only more widely networked Polyurethanes can be used. According to the invention For example, flexible PUR foams can be used in liquid processes Convert polyols whose hydroxyl numbers are well below 50 mg KOH / g lie. In contrast, the usual alcoholysis process Ren from the same soft foams polyols obtained, the Hy droxyl numbers are regularly above 200 mg KOH / g.

The polyol dispersions obtained according to the invention also contain Surprisingly, only small amounts of aromatic amines, such as Methylenediphenyldiamine or toluenediamine. According to the status of Alcohololysis polyols obtained using technology can usually be 1 detect up to 2 wt .-% of such aromatic amines, whereby additional measures for deamination become necessary.

Using the method according to the invention, it is possible for the first time to direct way to adapt the properties of the recycled polyols to the polyols, which were used for the production of the polyurethanes used. At least with soft polyurethanes, this was with the previously known ones Alcoholysis process not possible.

All polyure wastes are suitable for the process according to the invention thanen on the basis of soft to semi-hard, if necessary with  whose polymers and / or fillers are mixed polyurethanes for example based on polyether or polyester, as well as polyureas and their copolymers. The process and application engineering Ge viewpoints of the polyurethanes, whether they contain fillers or additives, are massive or foamed are of no importance for the invention Method. For procedural reasons, however, it makes sense to Use polyurethane waste in shredded form. The shredder The degree of efficiency is freely selectable and only affects the speed speed of the degradation reaction. The method according to the invention is suitable especially for polyurethanes with thermoplastic such as polyolefins, ABS or PVC and only of these are difficult to separate. With a suitable choice of reaction conditions such thermoplastics can be incorporated into the recyclate in finely divided form be prepared.

In the process according to the invention, cycli cal dicarboxylic acid anhydrides and / or dicarboxylic acids and / or their Derivatives, which, usually at elevated temperature, under water shutdown form cyclic dicarboxylic anhydrides, used, selected from the group of succinic anhydride, Glutaric anhydride, malic anhydride, Phthalic anhydride, dihalogenated and tetrahalogenated phthalic acid anhydrides, for example di- and tetrachlorophthalic anhydride or Di- and tetrabromophthalic anhydride or Diels-Alder adducts of Maleic anhydride. These anhydrides can also underlie lying dicarboxylic acids and / or their derivatives are used. According to the invention, mixtures of this compound can also be used Come into play. Suitable dicarboxylic acid derivatives, which cyclic Di carboxylic anhydrides can form, for example, esters of Di carboxylic acids. The weight ratio of the cyclic dicarboxylic acid hydride and / or dicarboxylic acids and / or derivatives of the polyurethane ethane waste is preferably 0.05-1: 1, more preferably 0.1-0.5: 1.  

Other acids such as the dicarboxylic anhydrides and dicarbon mentioned Acids can be used as additives in the process according to the invention for example to accelerate the degradation reaction or to achieve special properties, such as increasing flame resistance be set.

The process according to the invention is suitably carried out at temperatures from 140 to 250 ° C, preferably 180 to 220 ° C, wherein Usually reaction times of 1 to 10 hours are required. It has been shown that the degradation reaction according to the invention by basic Catalysts, such as alkali metal hydroxides and alkoxides and tertiary amines can be accelerated. If desired, such catalysts can be used in Amounts of 0.1 to 5 wt .-%, based on the total Reaction system can be added.

The decomposition reaction according to the invention takes place in the presence of polyethe Roles with a molecular weight of 500 to 6000 g / mol and a hydroxyl functionality from 2 to 5. Such polyetherols are commonly used in used in the production of polyurethanes. Are particularly suitable Propylene oxide-based polyetherols with molar masses of over 1000 g / mol and hydroxyl functionalities from 2 to 3. The weight ratio of the Po lyetherols to the polyurethane waste is preferably 0.2-2: 1, white ter preferably 0.5-1: 1.

An essential feature of the method according to the invention is in that the polyetherols with or before the degradation reaction carbon-unsaturated monomers of a ra physical grafting reaction. Through this measure me succeeds in dispersing the resulting heterogeneous products stood to stabilize. On the other hand, the implementation without such a graft tion reaction carried out, you get largely degraded poly urethane, however, the reaction takes place depending on the weight ratios of the reactants take place in the highly viscous to semi-solid state. Get the NEN reaction products are then usually also solid to hochvi skos and mostly heterogeneous to coarsely dispersed.  

When attempting the reaction only in the presence of diols or Po to carry out lyetherols or with these the degradation products in a never to bring the viscous, technically usable form usually inhomogeneous products. In contrast, the degradation reaction tion according to the invention in the presence of grafted polyetherols performed, finely dispersed liquid products with excellent results application properties. In particular arise no high hydroxyl functionality in the process according to the invention, but in contrast, low-functionality products that are repeated rum are suitable for the production of soft polyurethanes.

Suitable as carbon-unsaturated monomers containing carbonyl groups especially monomers containing acyl groups, such as (meth) acrylic acid, Ma linseic acid, fumaric acid, itaconic acid, crotonic acid as well as allyl and vinyl carboxylic acid esters. Such substances are preferably used here: the easily accessible, easy to use, inexpensive and given if they are readily polymerizable with other monomers. In particular be (Meth) acrylic acid, maleic acid, fumaric acid and / or are preferred their derivatives, such as their anhydrides and esters, are used. A Grafting with another carbon-unsaturated comonomer, such as styrene, may be desirable to e.g. Spersion stability increase or the particle size of the degradation products to control.

The weight ratio of the carbon unsaturated, carbonyl groups containing monomers to the polyetherols is preferably 0.01-0.2: 1, more preferably 0.05-0.1: 1.

The grafting reaction is suitably thermal or counter were from radical formers common for radical polymerization, such as peroxides or azo compounds. Such radical formers are ge suitably in a concentration of 0.1 to 5% by weight, preferably 0.5 to 2 wt .-%, based on the graft, used. Examples ge suitable radical formers are azodiisobutyronitrile, dibenzoyl peroxide, di  tert-butyl peroxide and cumene hydroperoxide. Choosing the radical image ner depends on the temperature at which the grafting reaction goes through leads. Suitable temperatures for the grafting reaction are 20 to 200 ° C. In the case of low temperatures, the grafting Accelerating action can be conventional accelerators, such as amines or Metal compounds can be added. The grafting reaction can be too Start of the process externally or in the for the degradation reaction set reaction container. It is also possible to graft to allow the reaction to take place simultaneously with the degradation reaction.

Furthermore, it may be advantageous to carry out the degradation reaction in the presence of Water and / or volatile carboxylic acids such as formic acid and vinegar acid to perform. With this procedure, all reagents ien, including the grafted polyetherols, presented and with poly urethane waste overlaid. At temperatures from around 140 ° C then ver the polyurethane under pressure by water and acid vapor liquid and converted together into a disperse liquid mass. After removing the volatile components at an elevated temperature structure, optionally under reduced pressure, become reaction products obtained with the aforementioned properties. This is advantageous Carrying out the reaction in a screw machine at Temperatu ren over 150 ° C and correspondingly short reaction times, the volatile components in a degassing zone of the extruder easily ent are distant.

The method according to the invention can be set or continuous be carried out using equipment customary in reaction technology. The simplest type of implementation is the discontinuous way of working in a heatable stirred tank. Here either the grafted Polyetherol, together with the cyclic dicarboxylic acid anhydrides and / or dicarboxylic acids and / or their derivatives, submitted or the  Grafting reaction in a stirred tank, for example during the heating process phase or during the degradation reaction. The metering of the normally shredded polyurethane waste follows at elevated temperature so that the reactor contents remain stirrable and kept at elevated temperature. The procedure is under Stirring is continued until the reactor contents are in a low-viscosity, finely dispersed state has passed. Then the reaction pro cooled and pumped out if necessary through a filter.

When choosing the reaction device and work equipment is too take into account that the reaction mixture in the main phase of Degradation reaction is in a highly viscous to pasty state. Through appropriately designed stirring or dispersing devices and Kneading elements can mix, disperse and heat transfer processes ge be optimized in a manner known to those skilled in the art.

A variant of the method according to the invention is the continuous one Working in multi-stage stirred reactors, screw machines or Kneading. This mode of operation is particularly advantageous when easily degradable polyurethane types and correspondingly high reaction temperatures, possibly with the help of catalysts, high Response rates can be achieved. By application high shear forces and selection of appropriate dispersing, The degradation reaction can be accelerated by screw or kneading tools conditions and the degree of dispersion of the reaction products improve. In the continuous work is suitably the crushed Polyurethane waste together with the dicarboxylic acid anhydrides and / or dicarboxylic acids and / or their derivatives with the addition of ge grafted polyetherols metered into the heated reaction zone. The Ver because time in the first and the further reaction zone is regulated so that largely exits the polyurethane after leaving the reaction zone is built and is in a liquid-dispersed state. Given if the addition of the grafted polyetherols at various Re action zones take place, for example, to be a suitable viscosity  position of the reaction mixture in the different zones chen. It is also possible to match the grafting reaction in the to carry out the reaction zones simultaneously with the degradation reaction.

The method according to the invention is illustrated in the following example games explained.

example 1

In an electrically heated and tempered machine equipped with a stirrer baren three-necked flask with 180 g of a long-chain polyether triol a molecular weight of approx. 4000 g / mol together with 12 g of acrylic acid butyl ester and 4 g of methyl ethyl ketone peroxide and 45 g of succinic anhydride heated to 200 ° C within one hour. At this temperature who the 300 g water-driven, based on tolylene diisocyanate (TDI) put polyurethane foam waste added so that the tem temperature is kept at 200 ° C. Then another 2 hours at Stirred 200 ° C and cooled with stirring. The finely dispersed product has following typical property picture:

Viscosity: 16 Pa · s at 25 ° C
Hydroxyl number: 30 mg KOH / g
Particle size: <30 µm
Toluene diamine: 0.5% by weight

The reaction product is in any proportions with polyetherols based on propylene oxide and can be mixed in such mixtures easy to process into new flexible polyurethane foams.

Example 2

In a test arrangement as described in Example 1, 30 g Succinic anhydride, 20 g phthalic anhydride, 5 g maleic anhydride hydride and 3 g of cumene hydroperoxide in 150 g of a polyether diol with egg  ner molar mass of 2000 g / mol heated to 210 ° C with stirring. At the This temperature will be 350 g based on methylene di-p-phenyldi Isocyanate (MDI) and a polymer-modified polyetherol Added flexible polyurethane foam within an hour and then intensively stirred for another hour at 210 ° C. After Ab cooling has the following characteristics:

Viscosity: 13 Pa · s
Hydroxyl number: 35 mg KOH / g
Acid number: 5 mg KOH / g
Particle size: <50 µm
Methylenediphenyldiamine: 0.2% by weight

The product can be mixed with polyetherols in any ratio and can be easily mixed into new polyurethane in such mixtures Process soft foams.

Example 3

In a two-stage, continuously operating stirred tank arrangement with a total reaction volume of 8 liters will be in the first Stirring reactor metered in the following quantities of substance per hour:

2800 g RRIM (reinforced reaction injection molded) - polyurea urethane
400 g succinic anhydride
1400 g polyether triol (molecular weight 4000 g / mol)
80 g of hydroxyethyl acrylate
60 g di-tert-butyl peroxide

The mixture flows continuously through the system at 200 ° C and leaves the second reactor as a viscous disperse mass. The reaction product has the following characteristics:

Viscosity: approx. 25 Pa · s, pseudoplastic
Hydroxyl number: 120 mg KOH / g
Acid number: 6 mg KOH / g
Methylenediphenyldiamine: 0.2% by weight

(When alcoholizing RRIM polyurine Fabric urethanes are much higher Get hydroxyl numbers.)

The short-glass fiber-containing, storage-stable product that with different Most diols and polyols are miscible, with the help of conventional catalysts with MDI to hard elastic to hard polyurethanes the.

Example 4

Semi-hard granulated polyurethane laminated with ABS-PVC films Tegral foam is in a weight ratio of 10 to 1.8 with amber acid anhydride metered into a counter-rotating twin-screw extruder and sheared at 220 ° C. In the second and third zone of the extruder who each in a weight ratio of 3 to 10, based on the polyurethane, use a mixture of 10 parts of the to produce the polyurethane base polyether triols (molecular weight 4000 g / mol) and 0.3 parts of acrylic acid and 0.2 parts of cumene hydroperoxide. That the extruder leaving product is stirred for a further 30 minutes at 200 ° C. After Ab cooling, the product has the following properties:

Viscosity: 19 Pa · s
Hydroxyl number: 45 mg KOH / g
Acid number: 5 mg KOH / g
Methylenediphenyldiamine: 0.1% by weight

Example 5

200 ml of water, 40 ml of formic acid and 20 g are placed in a pressure pot Succinic acid and 100 g of a polyether grafted with acrylic acid triols (molecular weight 4500 g / mol) with a hydroxyl number of 35 g / mol sets and with 150 g of a water-driven polyure made with TDI  than foam. The reaction vessel is closed and held at 150 ° C for an hour, a pressure of about 4 bar builds up. Then volatiles are removed at 150 ° C and ver with stirring with 100 g of a polyether triol (molecular weight 4500 g / mol) thins. A finely dispersed viscous liquid is obtained, from which with MDI a soft foam can be produced.

Claims (12)

1. Process for the preparation of isocyanate-reactive polyol dispersion NEN, in the polyurethane waste with cyclic dicarboxylic anhydrides from the group of succinic anhydride, glutaric anhydride, Äp rock acid anhydride, phthalic anhydride, dihalogenated phthalic acid hydride, tetrahalogenated phthalic anhydrides and Diels-Alder adducts of Maleic anhydride and / or the dicarboxylic acids underlying anhydrides and / or their de derivatives in the presence of polyetherols with a molecular weight of 500 to 6000 g / mol and a hydroxyl functionality of 2 to 5 at a tem temperature of 140 to 250 ° C are subjected to a degradation reaction, the polyetherols with coal before or during the decomposition reaction unsaturated carbonyl-containing monomers of a radical grafting reaction. 2. The method of claim 1, wherein polyurethane waste based from soft to semi-hard, possibly with other polymers and / or fillers mixed polyurethanes can be used. 3. The method according to claim 1 or 2, wherein the weight ratio of cyclic dicarboxylic acid anhydrides and / or dicarboxylic acids and / or their derivatives to the polyurethane waste is 0.05-1: 1. 4. The method according to at least one of the preceding claims, the weight ratio of the polyetherols to the polyurethane wastes len is 0.2-2: 1. 5. The method according to at least one of the preceding claims, being as carbon-unsaturated monomers containing carbonyl groups (Meth) acrylic acid, maleic acid, fumaric acid and / or their derivatives, optionally together with other carbon-unsaturated Como nomers can be used. 6. The method according to at least one of the preceding claims, wherein the weight ratio of the carbon unsaturated, carbonyl group-containing monomers to the polyetherols is 0.01-0.2: 1.   7. The method according to at least one of the preceding claims, the grafting reaction being carried out in the presence of radical formers leads. 8. The method according to claim 7, wherein as radical generator peroxides or Azo compounds are used. 9. The method according to claim 7 or 8, wherein the radical generator in one Amount of 0.1 to 5 wt .-%, based on the grafting mass used will. 10. The method according to at least one of the preceding claims, the degradation reaction being carried out in the presence of water under pressure leads. 11. The method according to at least one of the preceding claims, this continuously in multi-stage stirred reactors, screws machines or kneaders. 12. Use of the method according to at least one of the preceding claims produced polyol dispersions for manufacture development of polyurethanes.