DD141525A1 - METHOD OF RECOVERING HYDROGEN-ACTIVE COMPOUNDS FROM POLYURETHANE WASTE - Google Patents

Abstract

The invention relates to a process for recovery hydrogen-active compounds from polyurethane waste for Reuse for polyurethane synthesis. Goal and task of Invention is the creation of an economical method for Recovery of hydrogen-active compounds from polyurethane waste for the purpose of their reuse in polyurethane syntheses, The PUR waste will react with it after it has been comminuted Alcohols containing at least 2 OH groups and have a molecular weight of 60 to 500, such as ethylene glycol, Diethylene glycol, wherein the molar ratio of urethane or Urea groups to OH groups 1: .0.5 to 1: 3 and the ratio from allophanate or binret groups to OH groups 1: 1 to 1: 4 is. The reaction will be in a closed or open system Temperatures between 130 and 260 ° C performed. to uniform distribution of polyhydric alcohols on the Polyurethane surface. Solvent may be added.

Description

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Title of the invention:

Process for the recovery of hydrogen-active compounds from polyurethane waste

Field of application of the invention:

The invention relates to a process for the recovery of hydrogen-active compounds from polyurethane waste for reuse in polyurethane syntheses,

Characterization of known technical solutions:

It is known to crosslink via allophanate or binret groups. thermosetting polyurethanes or polyureas at temperatures above 120 ⁰ C by reversible cleavage of the allophanate structure in a urethane and isocyanate group or · the Binretstruktur in a urea and an isocyanate group in thermoplastic polymers, while at temperatures between 80 and 100 ⁰ C, the crosslinks again be formed .. ** ^ R. BECKER: Polyurethane, specialized book publisher Leipzig 1973_ /. This makes it possible, polyurethane (PUR) to process waste on Spritzgußmaschinsn or extruders / ~ DD-PS 119 054, 125 889 7 * ^{It is} not possible in this way the waste for other purposes, such as for _f Foam production or textile coatings to use. It is furthermore known to dissolve PU waste in one or more starting compounds to be used for the isocyanate-polyaddition, and then to carry out the polyaddition.

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However, this process can only be carried out if the PUR wastes are soluble in these compounds; this is not the case with crosslinked polyurethane / polyureas.

Is also known a decomposition of PUR by a alcoholysis by action of diols at 180. "250 ⁰ C / ~ GB-PS 1 492 838_ / _K of diols in the presence of Monoal.kylaminen / ~ DE-AS 2 557 172_ / or of diols with dialkanolamines / ~ DE-OS 2238109, US-P 3 708 440_ / at temperatures above 150 ⁰ C and of diols in the presence of carbonyl compounds at 130 ##. 230 C / "DD-PS 127 493_7 ·

Due to the relatively large molar excess of diols or, respectively, the sum of diols and alkanolamines in relation to the urethane groups, all these processes give products having a high OH number and thus a low average molecular weight. These products are not directly suitable for the production of the starting PUR on which the waste is based and must either be worked up accordingly or used for the manufacture of other products.

Object of the invention:

The aim of the invention is to provide an economical process for the recovery of hydrogen-active compounds from polyurethane waste for reuse in polyurethane synthesis. In terms of their chemical properties, the resulting hydrogen-active compounds should be such that they are suitable for synthesizing, in particular, the polyurethanes from which the waste originates.

parlecjunci of the essence of the invention:

The object of the invention is the recovery of hydrogen-active compounds from polyurethane (PUR) waste. The products obtained should be reused as compounds having at least two active hydrogen atoms for the polyurethane production process, the use preferably being for the preparation of the same polyurethanes from which the waste originates. According to the invention, this object is achieved by breaking up the comminuted ones PUR waste exposes a reaction with alcohols containing at least 2 OH groups, preferably 2 and / or 3 OH groups, and having a molecular weight of 60 to 500, preferably from 60 to 200, such as B. Äthylenglykol, diethylene glycol , Triethylene glycol, butanediol, hexanediol, trimethylolpropane, glycerol, wherein the molar ratio of urethane or urea groups to OH groups 1: 0.5 to 1: 3, preferably 1: 1 and the molar ratio of allophanate or Binretgruppen to OH Groups 1: 1 to 1: 4, preferably 1: 1.5, is.

The reaction is carried out in a closed or open system at temperatures between 130 and 260 ^° C., preferably between 170 and 240 ° C. Under these conditions, the allophanate groups are cleaved according to equation (1) and the urethane groups cleaved according to equation (2).

R-N-C-O-R'I

O = C + HO-R "'- OH I NH

I R "

O Il

R-NH-COR ¹

+ O = C-O-R '' '- OH

NH

R "

(1)

R-NH-C-O-R '> R-Nl-U + O = C-O-R'

(2)

2,

R'V'-OH

+ HO-R "'0H

Reacting analogously Binret- and urea groups »obtained in this way bi- or polyfunctional hydrogen-active compounds which have compared to the macrodiol or polyol used as starting material in the synthesis of PU only a slightly increased molecular weight and thus as starting materials for a renewed PUR synthesis can be used.

Since the amount of polyhydric alcohol required for the cleavage reaction is relatively low - on the order of 2 to 10 % by mass , based on the PUR-, it is desirable to use a diluent for the polyhydric alcohol and / or a solvent for The PUR to be used as such diluents and / or solvents can distillable, with isocyanates and alcohols under the given conditions, unreactive organic compounds such as acetone or other / cetones, tetrahydrofuran, dioxane, dimethylformamide, dimethyl sulfoxide and / or macrodiols and / or Macropolyols, such as polyester alcohols and / or polyether alcohols may be used «

When using low molecular weight solvents, the reaction is carried out in an autoclave. After completion of the reaction, the solvent can be removed by distillation, or it can also be used as a solvent in a renewed PUR synthesis.

When using macromolecular di- and / or polyols as diluents for the polyhydric alcohol, the reaction can be carried out both in an autoclave and in an open reaction vessel. It is expedient to use as diluent the polyester or polyether alcohol which

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based on the PUR waste. After completion of the reaction, the resulting homogeneous mixture can be used directly without separation to a renewed PUR synthesis »

The concentration of urethane, urea, allophanate and Binretgruppen in PUR waste product can be calculated by knowing the composition of the starting mixture or - for products of unknown composition - analytically, z. B, on the basis of IR spectra.

The reaction can be carried out by adding suitable catalysts, preferably organotin compounds, such as. Tin (II) -pctoate, dibutyltin dilaurate can be accelerated. The resulting reaction products are characterized by their OH and NH_ Endgruppenkonzentration. It is also possible to detect the sum of hydroxyl number and amine number by the reaction of both end groups with acetic anhydride. For the calculation of the amount of diisocyanate required for a renewed PU synthesis, the knowledge of this sum is sufficient.

The invention will be explained in more detail below with reference to two exemplary embodiments,

Implementation examples: ·

100 g of a polyurethane foam used for textile coatings, prepared from a prepolymer (I), which consists of 1140 g of a polyester alcohol (A) having an OH number of. 112.0 (Ff = 1000), 50 g of a polyethylene glycol having an OH number of 73.3 (M = 1530) and 592 g Hoxamethylendiisocyanat synthesized and then using water as

Chain extender / crosslinker was foamed, are crushed and poured over in an autoclave with a solution of 8.4 g A'thylenglykol in 300 ml of dried acetone. After purging with nitrogen, the mixture is heated to 220 C for 2 hours. After cooling, the acetone is evaporated from the resulting homogeneous solution. A viscous liquid having a sum of OH number and number of mint (determined by the consumption of acetic anhydride) of 118 is obtained. If a renewed PUR synthesis replaces 20% by weight of the diol components with this product, a prepolymer ( II) a foam having the same physical properties as the materials prepared from the prepolymer (I).

Example 2;

200 g waste of a used for textile coatings th PUR foam, prepared from a prepolymer (III), which consists of 1000 g of a polyester alcohol (B) having an OH number of 60 (M = 1.870). 10 g of polyethylene glycol having an OH number of 73.3 (M _n = 1530), synthesized 7.5 g of triethanolamine and 440 g of 4,4'-diphenylmethane diisocyanate and then foamed using water as a chain extender / crosslinker, are crushed and in a reaction vessel equipped with stirrer, thermometer, nitrogen inlet and outlet tube, with a solution of 15 g of butanediol (1.4) in SOO g of the polyester alcohol (B). Conn. The mixture is heated in a stream of nitrogen with stirring for 4 hours at 190 ⁰ C.

After cooling, the viscous, homogeneous product, which has a sum of OH number and Äminzahl (determined from the consumption of acetic anhydride) of 68, with the addition of 8 g of polyethylene glycol and 6 g of triethanolamine with 440 g of 4,4'-diphenylmethane diisocyanate directly into a prepolymer (IV) which can be processed in the same way as the prepolymer (III) by reaction with water to textile coatings with the same physical properties.

Claims (2)

210 729 Invention claims: 1 * Process for the recovery of hydrogen-active compounds from polyurethane Äballen for reuse for polyurethane synthesis, characterized in that the polyurethane waste at temperatures between 130 and 260 ⁰ C, preferably between 170 and 240 C _{1 of} a reaction with one or more alcohols exposed which contain at least 2 OH groups, preferably 2 and / or 3 OH groups, and have a molecular weight of 60 to 500, preferably 60 to 200, wherein the ratio of urethane and urea groups to OH groups 1: 0 , 5 to 1: 3, preferably 1: 1 and the ratio of allophanate and Binretgruppen to OH groups 1: 1 to 1: 4, preferably 1: 1.5, tows, Method according to item 1, characterized in that a diluent for the polyhydric alcohol and / or a solvent for the polyurethane is used. Process according to items 1 and 2, characterized in that the diluent for the polyhydric alcohol is a fiacrodiol or polyol having a molecular weight above 500, A process according to items 1 and 2, characterized in that the diluent for the polyhydric alcohol and / or the solvent for the polyurethane comprises an inert organic liquid, for example acetone, dioxane, tetrahydrofuran; Dimethylformamide, dimethyl sulfoxide or a mixture of such compounds. 5. Others according to items 1 to 4, characterized in that the reaction is carried out in an autoclave. 6. The method according to item 1 to 5, characterized in that the Reaktionsgemisoh a catalyst, preferably a Zinno.rganische compound such as tin (II) octoate or Oibutylzinndilaurat added.