Blends of biodegradable polymers and acrylic copolymers
The invention relates to a blend of one or more biodegradable polymers with one or more acrylic copolymers, for the purpose of improving the properties of the biodegradable polymer(s). The biodegradable polymer contains at least 10 weight percent of a biopolymer that is in less than ideal condition for processing. The “compromised” biopolymer may be undried biopolymer, may have a heat history (be “reprocessed”, “regrind” or “recycled”), or both. The acrylic copolymer(s) are present in the blend at a level of 0.1 to 15 weight percent, based on the weight of the total blend.
1. A biodegradable polymer composition having improved properties, said composition consisting of a homogeneous blend of:
a) 30 to 99.9 weight percent of one or more biodegradable polymers selected from the group consisting of polylactide and polyhydroxy butyrate or mixtures thereof; wherein said biodegradable polymer comprises from 25 to 75 weight percent of compromised, undried, non-virgin, recycled, regrind biodegradable polymer previously heated to a molten state with the remainder being virgin polylactide or polyhydroxy butyrate;
b) 0 -69.9 weight percent of one or more biopolymer selected from the group consisting of starch, cellulose, polysaccharides, aliphatic or aromatic polyesters, and polycaprolactone;
c) 2 to 4 weight percent of one or more acrylic copolymers based on the total weight of the blend,
d) optionally a low level of up to 10 weight percent of impact modifier, based on the weight of the polylactide, and
e) optionally one or more additives selected from the group consisting of heat stabilizers, internal and external lubricants, fillers, and pigments,
wherein said improved property is that the melt strength is increased by at least 100% or more compared to that of a biodegradable composition consisting of virgin-biodegradable polymer.
2. The biodegradable composition of claim 1 , wherein said impact modifier comprises at least two different types of impact modifiers.
3. The biodegradable of claim 1 wherein said acrylic copolymer has a weight average molecular weight of from 10,000-3,000,000 g/mol.
4. The biodegradable of claim 1 wherein the acrylic copolymer is a blend of two or more copolymers.
5. The biodegradable composition of claim 1 , wherein said composition is clear.
6. A process for improving the properties of a biodegradable polymer blend composition,
the method comprising the step of admixing to form a blend consisting of:
a) 30 to 99.9 weight percent of one or more biodegradable polymers selected from the group consisting of polylactide and polyhydroxy butyrate or mixtures thereof; wherein said biodegradable polymer comprises from 25 to 75 weight percent of undried, non-virgin, reground, recycled, biodegradable polymer previously heated to a molten state with the remainder being virgin polylactide or polyhydroxy butyrate;
b) 0 -69.9 weight percent of one or more biopolymer selected from the group consisting of starch, cellulose, polysaccharides, aliphatic or aromatic polyesters, and polycaprolactone;
c) 2 to 4 weight percent of one or more acrylic copolymers based on the total weight of the blend,
d) optionally a low level of up to 10 weight percent of impact modifier, based on the weight of the polylactide, and
e) optionally one or more additives selected from the group consisting of heat stabilizers, internal and external lubricants, fillers, and pigments
to form a homogeneous blended composition having a melt strength that is increased by at least 100% or more compared to that of the virgin biodegradable polymer.
7. The biodegradable composition of claim 6 , wherein said impact modifier comprises at least two different types of impact modifiers.
8. The biodegradable composition produced by the process of claim 6 wherein said acrylic copolymer has a weight average molecular weight of from 10,000-3,000,000 g/mol.
9. The biodegradable composition produced by the process of claim 6 wherein the acrylic copolymer is a blend of two or more copolymers.
10. The biodegradable composition produced by the process of claim 6 , wherein said composition is clear.
11. The biodegradable composition produced by the process of claim 6 , wherein one or more of said acrylic copolymers comprises 10-75 weight percent of methyl methacrylate units, 10 to 50 weight percent of butyl acrylate units, and from 0 to 80 weight percent of styrene, the total adding to 100 percent.