Polyphase biodegradable compositions containing at least one polymer of vegetable origin

A film produced from a polyphase biodegradable composition having good resistance to ageing comprising:

• a) 45-98% by weight, with respect to the sum of components (a) and (b), of a continuous phase comprising at least one hydrophobic polyester,
• b) 2-55% by weight, with respect to the sum of components (a) and (b), of at least one dispersed phase comprising at least one polymer of vegetable origin,
• said composition further comprising a further dispersed phase comprising 1-40% by weight, with respect to the total weight of the composition, of at least a polylactic acid which is rigid in comparison with the hydrophobic polyester forming the continuous phase, with a Young's modulus of more than at least 300%,
• wherein:
• the hydrophobic polyester is an aliphatic-aromatic polyester of the diacids-diol type having an aromatic part comprising polyfunctional aromatic acids selected from dicarboxylic aromatic compounds of the phthalic acid type and their esters and heterocyclic dicarboxylic aromatic acids, and an aliphatic part consisting of aliphatic dicarboxylic acids and aliphatic diols, said polyester having an aromatic acids content of from 30% to 90% by moles, with respect to the acid component, and
• the polymer of vegetable origin is starch,
• the composition exhibits an Elmendorf tear strength of more than 60 N/mm in the transverse direction upon filming,
• said composition comprising 5-50% by weight, with respect to the weight of the polymer of vegetable origin, of a plasticizer comprising at least 75% by weight, with respect to the total weight of said plasticizer, of a mixture of diglycerol, triglycerol and tetraglycerol.