Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Patent
1996-07-05
1997-11-04
Mosley, Terressa
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
502100, 502309, 502349, 502350, 528190, 528191, 528193, 528194, C08G 6300
Patent
active
056841167
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
Polyesters and copolyesters are in general prepared by a two-stage process, regardless of their structure, which can extend from aliphatic to completely aromatic via numerous possible variations. In the first stage, in particular, dicarboxylic acid esters are transesterified or dicarboxylic acids are esterified with excess dialcobols to prepare the esters to be subjected to polycondensation or a polyester precondensate which comprises a mixture of oligoesters and can have an average relative molecular weight, depending on the molar ratio of the starting compounds, of as a rule between 100 and 2000. Limited amounts of starting components of higher functionality, such as glycerol, pentaerythritol and trimellitic acid, can also be employed for any desired branching modification. Equivalent procedures for the first stage are the reaction of dicarboxylic acid chlorides with diols, the addition of ethylene oxide onto dicarboxylic acids, the esterification of an anhydride with a dialcohol, the reaction of anhydrides with epoxides and the reaction of dicarboxylic acids or dicarboxylic acid esters with the diacetate of a diol. The second reaction stage is the actual polycondensation, in which the desired high molecular weight of the polyesters or copolyesters must be achieved, alcohol and/or water being split off. As well as applying vacuum, passing through an inert gas and increasing the reaction temperature, the polycondensation is accelerated, in particular, by specific polycondensation catalysts.
A legion of polycondensation catalysts for acceleration of the polycondensation reaction has already been proposed for the preparation of film- and fibre-forming polyesters. Since the overwhelming majority of compounds mentioned in numerous patents have an inadequate catalytic activity or other disadvantages, almost exclusively Sb.sub.2 O.sub.3 has become accepted as the polycondensation catalyst in the art. Unfortunately, this catalyst has recently met objections in terms of environmental policy, so that its replacement generally seems desirable.
Attempts are continuously being made to provide substitute catalysts for Sb.sub.2 O.sub.3. In particular, alkoxy titanates, specifically tetrabutyl titanate, have already been proposed, these compounds being used either only for the transesterification (JA Patent 74 11 474), for the transesterification and polycondensation (JA-A 77 86 496) or only for the polycondensation (JA-A 80 23 196), since they are catalytically active for both stages. Since the use of titanium compounds causes discolorations in the polycondensed polyesters, according to JA-A 78 106 792, it is necessary to pretreat titanium compounds with various organic substances, for example amines, or to combine them with other polycondensation catalysts, in particular with Sb.sub.2 O.sub.3 (JA-A 78 109 597).
SUMMARY OF THE INVENTION
The object of the present invention is to provide, for the general synthesis of polyesters and copolyesters, new polycondensation catalysts as a replacement for Sb.sub.2 O.sub.3 which offer increased safety for the ecosystem and are distinguished in particular by a higher catalytic activity than Sb.sub.2 O.sub.3 and titanium tetrabutylate have, in each case in the same concentration.
The invention relates to a process for the preparation of polyesters and copolyesters by polycondensation of polyester-forming starting components, esters or oligoesters being prepared in a first reaction stage and subjected to polycondensation in a second reaction stage in the presence of titanium catalysts, which is characterized in that, in the polycondensation stage, a titanium dioxide/silicon dioxide coprecipitate having a composition of TiO.sub.2 :SiO.sub.2 =90:10 to 20:80 mol/mol and/or a titanium dioxide/zirconium dioxide coprecipitate having a composition of TiO.sub.2 :ZrO.sub.2 =95:5 to 70:30 mol/mol is employed as the polycondensation catalyst for polycondensation of the esters or oligoesters.
DESCRIPTION OF PREFERRED EMBODIMENTS
On the basis of the fact that TiO.sub.2 is a poor
REFERENCES:
patent: 2906737 (1959-09-01), York, Jr.
patent: 3023192 (1962-02-01), Shivers, Jr.
patent: 4421908 (1983-12-01), East
Derwent abstract JP 48041949.
Eric A. Barringer et al., Formation, Packing, and Sintering of Monodisperse TiO.sub.2 Powders, Dec. 1982, Communications of the American Ceramic Society, pp. C-199 to C-201.
Berger Ulrich
Bohringer Bertram
Haferland Klaus
Martl Michael
Mezger Thomas
Akzo Nobel N.V.
Mosley Terressa
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