Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1994-09-16
1996-04-30
Szekely, Peter A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
2641761, 26421124, 26421113, 26421115, 264211, 264349, C08L 300, B29B 700, B29C 4736, B28B 320
Patent
active
055126170
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to improvements in the production of materials based on modified starch present in an intimate admixture with selected thermoplastic polymer compounds and to molded articles manufactured from said materials.
2. Discussion of Related Art
Numerous recent proposals deal with the attempt of opening up an extended range of possible fields of application to high molecular weight polymer compounds of natural origin--and especially to starch, among these. All of this work has been based on the recognition that native starch, together with limited amounts of water and/or further auxiliary materials, by means of a thermomechanical digestion can be converted into a thermoplastic material that can be processed in a conventional manner, for example by injection molding. The thermomechanical digestion by employing elevated temperatures and pressures is possible, more specifically, in conventional extruders provided upstream of the shaping step. From the comprehensive literature, here particular reference may be made to the publication by R. F. T. Stepto et al., Injection Moulding of Natural Hydrophilic Polymers in the Presence of Water, Chimia 41 (1987), No. 3, 76-81, and the literature quoted therein.
Extensive work deals with the improvement of the product properties in the thermoplasticized starch by the concomitant use of selected organic auxiliary liquids in the starch digestion. Here, as an example, the PCT patent application No. WO 90/05 161 may be mentioned. Herein it is proposed to add loading materials to the native starch, which loading materials decrease the melting temperature of the starch and are additionally characterized by a definite solubility parameter. As the loading materials there have been especially mentioned lower polyfunctional alcohols such as ethyleneglycol, propyleneglycol, glycerol, 1,3-butanediol, diglyceride, appropriate ethers and further compounds.
Materials based on starch which has been thermoplasticized in that manner are distinguished by a very much restricted utility. The reason is the extremely marked hydrophilicity of the material. Accordingly, the replacement nowadays desired in wide areas of polymer compounds of synthetic origin by a biologically degradable polymer material of natural origin is possible only to a very limited extent or is not even possible at all.
More recent proposals relate to the attempt of combining thermoplasticized starch with synthetically produced water-resistant polymer compounds in such a manner that the hydrophilic starch-based polymer compound exhibits an increased stability against hydrophilic solvents, while neverthelesss substantial proportions of the materials or molded article, respectively, are comprised of the starch. From the pertinent literature, the PCT patent application No. WO 90/01 043 may be mentioned. Described therein is coating hydrophilic polymers, such as starch, with selected aliphatic polyesters which in turn are degradable, especially by bacteria or fungi. In particular there is described coating molded articles made of starch with polyesters derived from lower hydroxycarboxylic acids, such as glycolic acid, lactic acid, hydroxybutyric acids and hydroxyvaleric acid. Since such layers when combined do poorly adhere to each other, an improvement of the adhesion is proposed by some preceding treatment of the starch surface and/or by the addition of a solvent or swelling agent for the starch to the coating solution.
Another approach--towards the same goal--is described by EP-A2-327 505. Herein, polymer mixed materials have been described which are recovered from a melt of water-containing destructured starch and at least one water-insoluble synthetic thermoplastic polymer compound. The procedure in detail is as follows: First, a thermoplasticized starch is produced--and worked up to form granules--from starch in an untreated or pretreated form with the addition of auxiliary materials such as hydrogenated fatty acid triglycerides, lecithin and especially w
REFERENCES:
patent: 4600400 (1986-07-01), Guevarra et al.
patent: 5095054 (1992-03-01), Lay et al.
Stepto, R., "Injection Moulding of Natural Hydrophilic Polymers in the Presence of Water", Tecnologie, Chima 41, Mar. 1987.
Szejti, V., "Bestimmung der Dissoziationskonstanten fur Amylose-Einschlussverbindungen" Starch/Starke 30, Verlag Chemmie, 1978, pp. 85-91.
Kruger, E., "Stakeeinschlussverbindungen und ihre Bedeutung beim Maischen", Monatsschrift fur Brauwissenschaft, Dec. 1984 pp. 505-512.
Davies, T., "Inclusion Complexes of Free Fatty Acids with Amylose". Starch/ Starke 32, Verlag Chemie 1980, pp. 149-158.
Beck Michael
Ritter Wolfgang
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Ortiz Daniel S.
Szekely Peter A.
Wood J. Daniel
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