Biodegradable polymer masterbatch, and a composition derived therefrom having improved physical properties

A biodegradable polymer composition, comprising:

• a masterbatch melt blend comprising particles of at least one particulate filler dispersed in at least one biodegradable thermoplastic polymer comprising a biodegradable aliphatic-aromatic copolyester;
• a biodegradable polyester amide polymer or copolymer;
• a derivative thereof;
• or any combination thereof;
• the amount of said at least one biodegradable thermoplastic polymer ranging from about 25% to about 50% by weight and the amount of said at least one particulate filler ranging from about 50% to about 75% by weight, said percent by weight being based upon the total amount by weight of said at least one biodegradable polymer and said at least one particulate filler;
• said at least one particulate filler having a mean particle diameter of from about 0.5 micron to about 40 microns wherein at least about 75% by weight of the particles have a mean particle diameter of from about 0.5 to about 20 microns;
• said masterbatch melt blend subsequently blended with at least one additional biodegradable thermoplastic polymer selected from said one or more masterbatch biodegradable thermoplastic polymers, the total amount of said at least one masterbatch biodegradable polymer and said at least one additional biodegradable polymer being from about 55% to about 90% by weight and the total amount of all of said particulate fillers being from about 10% to about 45% by weight based upon the total weight of all of said biodegradable thermoplastic polymers and the total weight of all of said particulate fillers;
• and
• wherein said blend composition has a strength at break load of at least 20% greater than the strength of said blend composition compounded in a single stage.

A process for forming a blend of at least one biodegradable polymer and at least one particulate filler, comprising the steps of:

• forming a biodegradable thermoplastic polymer masterbatch composition by melt blending in a high shear extruder having an outer diameter/inner diameter screw ratio of at least about 1.6/1 at least one particulate filler and at least one biodegradable thermoplastic polymer comprising a biodegradable polylactic acid or a biodegradable polylactic acid-based polymer, a copolymer, or a blend thereof;
• a biodegradable aliphatic-aromatic copolyester;
• a biodegradable aliphatic polyester;
• a biodegradable polyesteramide polymer or copolymer;
• or a biodegradable cellulose or a derivative thereof;
• or any combination thereof;
• said particulate filler having a mean particle diameter of from about 0.5 micron to about 40 microns wherein at least about 75% by weight of the particles have a mean particle diameter of from about 0.5 to about 20 microns, said melt blending occurring at a temperature above the melting point of the highest melting point biodegradable thermoplastic polymer, the amount of said at least one biodegradable thermoplastic polymer ranging from about 25% to about 50% by weight and the amount of said at least one particulate filler ranging from about 50% to about 75% by weight, said percent by weight being based upon the total amount by weight of said at least one biodegradable polymer and said at least one filler,
• subsequently adding and melt blending at least one additional biodegradable thermoplastic polymer selected from said one or more masterbatch biodegradable thermoplastic polymers, the total amount of said at least one masterbatch biodegradable polymer and said at least one additional biodegradable thermoplastic polymer being from about 55% to about 90% by weight and the total amount of all of said particulate fillers being from about 10% to about 45% by weight based upon the total weight of all of said biodegradable thermoplastic polymers and the total weight of all of said particulate fillers, said blending said being at a temperature above the melting point of the highest melting point biodegradable thermoplastic polymer;
• and
• wherein said blend composition has a WVTR according to ASTM E 398-03 of about 30 or less.

A process for forming a blend of at least one biodegradable polymer and at least one particulate filler, comprising the steps of:

• forming a biodegradable thermoplastic polymer masterbatch composition by melt blending at least one particulate filler and at least one biodegradable thermoplastic polymer comprising a biodegradable polylactic acid or a biodegradable polylactic acid-based polymer, a copolymer, or a blend thereof;
• a biodegradable aliphatic-aromatic copolyester;
• a biodegradable aliphatic polyester;
• a biodegradable polyesteramide polymer or copolymer;
• or a biodegradable cellulose or a derivative thereof;
• or any combination thereof;
• said particulate filler having a mean particle diameter of from about 0.5 micron to about 40 microns, said melt blending occurring at a temperature above the melting point of the highest melting point biodegradable thermoplastic polymer, the amount of said at least one biodegradable thermoplastic polymer ranging from about 25% to about 50% by weight and the amount of said at least one particulate filler ranging from about 50% to about 75% by weight, said percent by weight being based upon the total amount by weight of said at least one biodegradable polymer and said at least one filler,
• subsequently adding and melt blending at least one additional biodegradable thermoplastic polymer selected from said one or more masterbatch biodegradable thermoplastic polymers, the total amount of said at least one masterbatch biodegradable polymer and said at least one additional biodegradable thermoplastic polymer being from about 55% to about 90% by weight and the total amount of all of said particulate fillers being from about 10% to about 45% by weight based upon the total weight of all of said biodegradable thermoplastic polymers and the total weight of all of said particulate fillers, and said blending said being at a temperature above the melting point of the highest melting point biodegradable thermoplastic polymer.

A biodegradable polymer composition, comprising:

• a masterbatch melt blend comprising particles of at least one particulate filler dispersed in at least one biodegradable thermoplastic polymer comprising a biodegradable polylactic acid or a biodegradable polylactic acid-based polymer, copolymer or blend thereof;
• a biodegradable aliphatic-aromatic copolyester;
• a biodegradable aliphatic polyester;
• a biodegradable polyester amide polymer or copolymer;
• or a biodegradable cellulose ester or a derivative thereof;
• or any combination thereof;
• the amount of said at least one biodegradable thermoplastic polymer ranging from about 25% to about 50% by weight and the amount of said at least one particulate filler ranging from about 50% to about 75% by weight, said percent by weight being based upon the total amount by weight of said at least one biodegradable polymer and said at least one particulate filler;
• said at least one particulate filler having a mean particle diameter of from about 0.5 micron to about 40 microns wherein at least about 75% by weight of the particles have a mean particle diameter of from about 0.5 to about 20 microns;
• said masterbatch melt blend subsequently blended with at least one additional biodegradable thermoplastic polymer selected from said one or more masterbatch biodegradable thermoplastic polymers, the total amount of said at least one masterbatch biodegradable polymer and said at least one additional biodegradable polymer being from about 55% to about 90% by weight and the total amount of all of said particulate fillers being from about 10% to about 45% by weight based upon the total weight of all of said biodegradable thermoplastic polymers and the total weight of all of said particulate fillers;
• and
• wherein said blend composition has a break load of at least 20% greater than the break load of said blend composition compounded in a single stage.