Removal of heteropoly compounds from polyethers, polyesters and

Details Removal of heteropoly compounds from polyethers, polyesters and Removal of heteropoly compounds from polyethers, polyesters and

1997-03-27

1998-04-21

Acquah, Samuel A.

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

Synthetic resins

Treating polymer containing material or treating a solid...

528482, 528488, 528494, C08F 600, C08J 300

Patent

active

057418888

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a method of removing heteropoly compounds from polyethers, polyesters and polyether esters, or solutions thereof, which comprise such heteropoly compounds, by mixing them with an ether whose polarity is so low that its addition leads to the deposition in a separate phase of the heteropoly compound present in the polymer phase.
Polyethers, polyesters and polyether esters are employed widely, for example in hydraulic fluids or as a diol component in the preparation of polyurethanes. They are prepared by cationic polymerization or copolymerization of appropriate monomers, such as, for example, cyclic ethers, acetals, polyalcohols or lactones, with the aid of Bronstedt or Lewis acid catalysts. Catalysts which have proven particularly advantageous for a ring-opening polymerization are heteropoly acids and heteropoly acid salts, referred to collectively below as heteropoly compound(s) or HPA. For establishing the desired polymer molar mass and/or for preparing specific, endgroup-modified derivatives, it is common for substances to be present during polymerization whose incorporation leads directly or indirectly to chain termination. Examples of such substances are carboxylic acid derivatives, alcohols and water.
JP-A-83 028/1983 describes, for example, the polymerization of tetrahydrofuran (THF) in the presence of a carboxylic anhydride or carbonyl halide to form polyTHF diesters, in which a heteropoly acid is used as catalyst.
EP 126 471 discloses the HPA-catalyzed polymerization of THF and the copolymerization of THF with various other cyclic ethers in the presence of water to form polyether glycols. EP 158 229 describes the preparation of polyether glycols by copolymerization of cyclic ethers with difunctional and higher polyfunctional alcohols.
According to JP 61-200120, lactones can be polymerized, alone or together with cyclic ethers, in the presence of hydroxyl-containing compounds and using heteropoly acids as catalysts.
In accordance with EP 503 393 and EP 503 394, polyether glycol monoethers and polyether glycol monoesters can be prepared by polymerizing cyclic ethers in the presence of monoalcohols or monocarboxylic acids and with HPA catalysts.
These polymerization processes for preparing polyethers, polyesters and polyether esters are accompanied by the formation of polymer phases which, owing to incomplete reaction, still include residues of monomer(s), of compound(s) leading to chain termination, any solvents employed, and dissolved heteropoly compound(s). The percentage amount of HPA catalyst dissolved in the polymer phase is considerable with these reactions and may be up to 1% by weight or more, based on the polymer phase. If separation is configured merely as a distillation to remove unreacted monomer, chain termination reagent (s) and any solvent employed from this phase, then the dissolved catalyst is not precipitated out but remains in dissolved form in the polymer. On the one hand, this must be prevented on quality grounds; on the other hand, it is desirable for reasons of cost--since heteropoly acids are very expensive--to recover the majority of the catalyst.
It is also known that heteropoly compounds break down over time, a process which is intensified under thermal stress. Such breakdown occurs principally by hydrolysis, to form the corresponding oxides. The breakdown of heteropoly compounds can be slowed down, or even entirely prevented, by means, inter alia, of the addition of an ether, as has been described, for example, by A. Aoshima, S. Yamamatsu and T. Yamaguchi in Nippon Kagaku Kaishi (1990) 233.
To solve the problem of the separation of heteropoly compounds, EP 181 621 proposes the addition to the polymer phase of a hydrocarbon or halogenated hydrocarbon, whereby the majority of the dissolved heteropoly acid is precipitated and/or deposited as a separate phase. The separated hydrocarbon/polymer phase is subsequently treated with a solid adsorbent. Stabilization of the heteropoly compounds, however, is not achieved by the precipitation with a (possibly h

REFERENCES:
patent: 5414143 (1995-05-01), Weyer et al.
AOSHIMA et al., (Japanese title), No. 3, 1990, pp. 234-242.

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