Polyesters composed of at least one dicarboxylic acid or one dicarboxylic acid derivative and of at least one diol are known from the literature. In particular, polybutylene terephthalate, composed of the aromatic dicarboxylic acid “terephthalic acid”, has achieved major economic importance. Biodegradable polyesters are of constantly increasing importance in particular for the packaging of foods, examples being polybutylene adipate-co-terephthalate and polybutylene sebacate-co-terephthalate. Recently, interest has focused on polyesters based on dicarboxylic acids such as succinic acid, sebacic acid, or 2,5-furandicarboxylic acid, or on dials such as 1,4-butanediol, these being obtainable from renewable raw materials.
The use of nucleating agents such as lime or chalk in the polyesters obtainable commercially has been thoroughly studied. Nucleating agents are frequently used in order to accelerate crystallization or to shift the recrystallization point to higher temperatures. In the injection-molding application this permits reduction of cycle times and conservation of resources. Nucleation can also improve the transparency of thin-walled components. In particular, addition of nucleating agents can improve the processability and isolation of polymers, especially amorphous polymers. The use of nucleating agents that are typical for injection-molding applications, for example talc, chalk, or alkali metal salts of carboxylic acids is known (Modern Polyesters: “Chemistry and Technology of Polyesters and Copolyesters” (book by John Scheirs (ed.) and Timothy E. Long (ed.), Wiley-Verlag, published 2003, pp. 515-520). Talc does not always lead to a satisfactory result in the polyesters mentioned in the introduction (component i).
USPTO Backgrounds
USPTO Backgrounds