Melt-stable lactide polymer composition and process for manufacture thereof

An amorphous melt-stable lactide polymer composition, comprising:

• (a) a plurality of polylactide polymer chains, said plurality of polylactide polymer chains resulting from the polymerization of a lactide mixture comprising about 5 to about 50 percent by weight meso-lactide and about 95 percent by weight or less L-lactide;
• (b) lactide in a concentration of less than about 2 percent by weight;
• (c) water, if present at all, present in a concentration of less than about 1000 parts-per-million;
• and
• (d) a stabilizing agent in an amount sufficient to reduce depolymerization of said plurality of polylactide polymer chains during melt-processing, such that the generation of lactide is less than about 2 percent by weight of the composition from a devolatilized sample in the first hour at a temperature of 180.degree. C. and atmospheric pressure.

A melt-stable lactide polymer composition comprising:

• (a) a plurality of polylactide polymer chains, said plurality of polylactide polymer chains having a number average molecular weight of from about 10,000 to about 300,000;
• (b) lactide in a concentration of less than about 2 percent by weight;
• (c) water, if present at all, present in a concentration of less than about 1,000 parts-per-million;
• and
• (d) residual catalyst in a molar ratio of monomer to catalyst of greater than about 3000:1.

A process for the manufacture of a melt-stable lactide polymer composition, comprising the steps of:

• (a) providing a lactide mixture, wherein said mixture contains about 5 percent by weight to about 50 percent by weight meso-lactide and about 95 percent by weight or less L-lactide;
• (b) polymerizing said lactide mixture to form polylactide and unreacted monomer in the presence of catalyst means for catalyzing the polymerization of lactide to form polylactide;
• (c) adding a stabilizing agent in an amount sufficient to reduce depolymerization of polylactide during melt-processing such that the generation of lactide is less than about 2 percent by weight of the composition from a devolatilized sample in the first hour at a temperature of 180.degree. C. and atmospheric pressure;
• and
• (d) devolatilizing the polylactide to remove unreacted monomer and residual water.