Thermoplastic starch compounds

• Main Authors: ERICH BROCKER, MARTIN HALTER, ERNST SCHWAB
• Format: Patent
• Language: English
• Published: 15.10.2009
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; CHEMISTRY; COMPOSITIONS BASED THEREON; COMPOSITIONS OF MACROMOLECULAR COMPOUNDS; HUMAN NECESSITIES; HYGIENE; MEDICAL OR VETERINARY SCIENCE; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; PREPARATIONS FOR MEDICAL, DENTAL, OR TOILET PURPOSES; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; THEIR PREPARATION OR CHEMICAL WORKING-UP; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

Homogenous, undried, melt-extruded thermoplastic composition comprises 30-60 wt.% of dry substance (a) of native or chemically modified starch, at most 11 wt.% of dry substance (b) of at least one further biopolymer, which includes carrageenan, other polysaccharides or protein, at least one softener (c) and maximum 20 wt.% of added water (d). Independent claims are included for: (1) a method for preparing the thermoplastic composition, comprising (i) mixing (a), (b), (c) and (d), (ii) adding the obtained mixture in an extruder and melted in the extruder at increased pressure of 10-300 atmosphere, increased temperature of at least 40[deg] C above room temperature and preferably product temperature of 60-150[deg] C, increased shearing of 0.15-0.67 kilowatt-hour (kWh)/kg and short dwell time between the first contact of all components after adding in the extruder and the outlet of the melted homogenous mixture from the extruder of maximum 5 (preferably 2) minutes, where the total water content is less than 20 wt.% of the total weight to obtain the homogenous thermoplastic compound; (2) a molded body, preferably soft capsule, comprising a cover made of the homogenous, thermoplastic composition; and (3) a method for preparing the molded body, comprising preparing the homogenous, thermoplastic composition by the above method and forming a molded body in a molding process (preferably rotary die-process).