Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1995-06-15
1997-05-20
Acquah, Samuel A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528272, 528301, 528361, 525440, 264239, 435117, 435132, 435135, 435931, C08G 6382, C12P 1700
Patent
active
056313438
DESCRIPTION:
BRIEF SUMMARY
This application is 371 of PCT/GB93/02461 filed Nov. 30, 1993.
The present invention relates to a process for producing polyesters or polyester(amide)s by enzyme catalysed reaction of monomers and to polyesters or polyester(amide)s having unique properties which may be obtained by that process.
Polyesters are well known industrial products finding applications principally as moulded articles in, for instance, the car industry. They are also of interest as the intermediates in the production of polyurethanes, which are also used to form moulded articles. Polyesters are reacted with isocyanates to form polyurethanes. The characteristics of the resulting polyurethane depend at least in part on those of the polyester.
Polyesters are typically produced by chemically catalysed reactions using elevated temperatures, strong acids and long reaction times. Competition between esterification, transesterification and hydrolysis limits the molecular weight of the products. Moreover these processes are accompanied by the formation of quantities of unwanted by-products, such as cyclic esters, and have the added disadvantage that the catalyst is difficult to remove. Furthermore, it is necessary to remove the water produced by the reaction in order to force the equilibrium towards products. If the presence of by-products and residual catalyst is not to degrade the properties of the desired material, complex arrangements are required to prevent their formation or remove them after the main reaction (see e.g. EP-A-0425201).
Polyester(amide)s were fashionable as materials for moulded products in the 1960's and 1970's but became less popular because they were found to become yellow as they aged. There has recently been an increased demand for polyester(amide)s especially those based on adipic acid/methylethanolamine. However, methylethanolamine has a relatively low boiling point and cannot be used in conventional chemically catalysed, high temperature polyesterifications unless the reaction is conducted under very high pressure.
The present invention seeks to overcome the difficulties of chemically catalysed reactions by use of lipase enzymes. Whilst lipasos have been known for some time for simple esterification and transesterification reactions (see, e.g. EP-A-0383 405) and stereoselective oligomerisations (see, e.g. Margolin A. L. et al., Tet. Letters, 28: 1607-1610,(1987)), only limited use has been made of lipasos in polyesterification. In particular Wallace and Morrow, J. Polymer Science Part A, 27, 2553-2562 (1989) and Gutman, Mat. Res. Soc. Symp. Proc., 174, 217-222 (1990) have succeeded in forming polyesters of high weight average molecular weight starting from dicarboxylic acid diestars where the ester moiety is highly activated (2,2,2-trichloroethyl esters) or from esters of hydroxycarboxylic acids and diesters of hydroxy dicarboxylic acids. However these processes have relied upon the use of organic solvents.
The present invention relates to a solventless enzymatic polyesterification process which not only avoids the disadvantages of earlier chemical and enzymatic techniques but remarkably affords polyesters of high weight average molecular weight, and narrow dispersity whilst also being extremely pure in terms of freedom from unwanted by-products. The invention further provides novel polyesters obtainable by this process.
The present invention in one aspect provides a process for producing a polyester comprising as repeating units
(i) residues of at least one aliphatic hydroxycarbcxylic acid or derivative thereof; or
(ii) residues of (a) at least one aliphatic dicarboxylic acid or derivative thereof, (b) at least one aliphatic hydroxyamine, diol or polyol, and optionally (c) at least one aliphatic hydroxycarboxylic acid or derivative thereof;
which process comprises reacting the components defined in (i) or the components defined in (ii) in the absence of a solvent and in the presence of a lipase such that the molar ratio of acid groups to hydroxyl groups in the reactants is 1:.1 to 1:1.1.
As used herein the term
REFERENCES:
Gross et al "Enzymes In Organic Media as Catalysts for Polyester Synthesis", Polym. Mater. Sci. Eng., 74 (2-3), p. 67 (1996), Aug. 16, 1996 .
Binns Falmai
Taylor Alan
Acquah Samuel A.
Baxenden Chemicals Limited
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