Process of preparing polyol-containing dispersions and their use

Details Process of preparing polyol-containing dispersions and their use Process of preparing polyol-containing dispersions and their use

1993-11-01

1995-04-25

Lovering, Richard D.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From reactant having at least one -n=c=x group as well as...

25218224, 25218225, 25218226, 252308, 252309, 521174, 528 60, 528 64, B01J 1300, C08G 1810, C08G 1832, C09K 300

Patent

active

054100089

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to a process for preparing polyol-containing dispersions by alcoholyzing polyurethane-urea waste and to the use of these dispersions for preparing new polyurethane-ureas.


BACKGROUND OF THE INVENTION

It is already known that polyurethane (PUR) and polyureas (PU), in particular foams, can be converted by alcoholic decomposition into homogeneous polyol-containing liquids which are directly suited for making rigid foams of PUR. Various types have become known in this field, the following publications being here cited by way of example:
DE-OS 25 16 863, U.S. Pat. No. 3,109,824, U.S. Pat. No. 3,404,103, DE-OS 25 57 172, DE-PS 27 38 572 or DE-PS 37 02 495.
The known processes have in common that alcoholysis is carried out with a considerable excess of diols or polyols to decompose the polyurethanes to such a degree that homogeneous polyol mixtures are obtained whose viscosity is low enough to reuse them directly or in homogeneous mixtures with short-chain polyols for making rigid polyurethanes. Therefore, all of the products obtained in these methods have a high hydroxyl equivalent which limits their application to the production of rigid polyurethanes. The methods mainly differ from each other by special reaction conditions, catalysts and process techniques.
Products which are suited for the manufacture of flexible to semirigid foams with respect to their viscosities and hydroxyl equivalents could so far not be recovered from polyurethanes and polyureas by alcoholic decomposition. Likewise, products which can be reused for the renewed preparation of polyurethane-ureas could so far not be recovered from polyurethane-ureas by alcoholic decomposition. In particular, a practicable method which serves to decompose RIM (reaction-injection-molding) or R-RIM (reinforced-reaction-injection-molding) parts based on polyurethane-ureas used on a large scale in the automotive industry and which yields reusable products has so far not become known.


SUMMARY OF THE INVENTION

It is therefore the object of the present invention to provide a process for decomposing polyurethane-urea waste, whereby polyol-containing products which are especially suited for the renewed preparation of polyurethane-ureas can be obtained through a simple alcoholysis reaction.
In accordance with the invention this object is accomplished through a process for preparing polyol-containing dispersions by reacting polyurethane-urea waste with at least one linear and/or branched-chain diol and/or polyol with a mol mass of 50-1000 g/mol in a ratio by weight of polymer waste to diol and/or polyol of greater than 3:1 at a temperature of 150.degree.-250.degree. C., optionally in the presence of acid or basic catalysts, and by dispersing the reaction product in at least one primary polyol with a mol mass up to about 6000 g/mol.
Primary polyols are polyols or polyol mixtures which are used for preparing polyurethanes and polyurethane-ureas.
Surprisingly enough, it has been found that polyurethane-ureas can be decomposed in the process of the invention by using small diol and/or polyol amounts. This yields viscous products which can also be dispersed in any desired ratio in high-molecular polyols (primary polyols) without the application of a special force, with the resultant dispersions having a high stability at relatively low viscosities.
The different properties of the polyurethane-ureas as compared with polyurethanes become apparent in the course of the decomposition process through the fact that two-phase substance mixtures and homogeneous products are not formed in the case of polyurethane-ureas, but milky turbid compositions which, however, lose their disperse character neither in this state nor when being diluted with primary polyols.
This unexpected course of the alcoholysis reaction, which only takes place when polyurethane-urea products are alcoholyzed, is normally independent of the kind of diol or polyol used for alcoholysis, but it can only be observed when, in contrast to the quantitative ratios of

REFERENCES:
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patent: 3325421 (1967-06-01), Muller
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patent: 4451583 (1984-05-01), Chesler
patent: 4518521 (1985-05-01), Heusch et al.
patent: 4530941 (1985-07-01), Turner et al.
patent: 5274004 (1993-12-01), van der Wal

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