Thermoplastically processable starch and a method of making it
First Claim
1. A method of preparing thermoplastically processable starch which is a substantially water free, combination of starch with at least one additive, the method comprising admixing starch with at least 5 weight percent based on the weight of the mixture of at least one additive, said additive being such that it reduces the melting point of the starch in the mixture to below the decomposition temperature of the starch, said additive having a solubility parameter of more than 15 cal1/2 cm-2/3, said additive having a vapor pressure of less than 1 bar in said mixture at a temperature of about the melting point of said mixture, and melting and mixing said admixture until it is substantially water free and until the crystalline content is less than 5%.
3 Assignments
0 Petitions
Accused Products
Abstract
In order to produce thermoplastically processable starch, an additive or plasticizer respectively is mixed with native or natural starch and the mixture is caused to melt by the application of heat and mechanical energy. The additive is a substance which lowers the melting point of the starch so that the melting point of the starch together with this additive lies below the decomposition temperature of the starch and the additive furthermore has a solubility parameter of over 15 cal1/2 cm-3/2. After the mixture of starch and additive is molten, the melt is mixed until it is at least almost homogeneous. The vapor pressure of the additive within the melting range of the mixture of starch and additive should be less than one bar. Preferably the mixing process is executed without the presence of water.
139 Citations
27 Claims
- 1. A method of preparing thermoplastically processable starch which is a substantially water free, combination of starch with at least one additive, the method comprising admixing starch with at least 5 weight percent based on the weight of the mixture of at least one additive, said additive being such that it reduces the melting point of the starch in the mixture to below the decomposition temperature of the starch, said additive having a solubility parameter of more than 15 cal1/2 cm-2/3, said additive having a vapor pressure of less than 1 bar in said mixture at a temperature of about the melting point of said mixture, and melting and mixing said admixture until it is substantially water free and until the crystalline content is less than 5%.
- 20. A thermoplastically processable starch comprising a substantially water free, homogeneous mixture having a crystalline content of less than 5% of starch and at least 5 weight % of at least one additive having a solubility parameter of more than 15 cal1/2 cm-3/2, said additive having a vapor pressure in the mixture of less than 1 bar at about the melting point of the homogeneous mixture, and the melting point of the mixture being lower than the decomposition temperature of the starch.
Specification