Patent ID: 8496868
Filing Date: 2013-07-30
Classification: B29C,B29K,C08J,Y10T

Abstract:
1. A method of making a blown PLA shrink film comprising 97.5 to 100 percent, by weight, polylactic acid polymer blend, which film, upon exposure to 95° C. heat for 10 seconds, exhibits shrinkage in the length direction and negative shrinkage (a negative value indicates growth) in the cross direction relative to the original dimensions of the shrink film, the method comprising (a) providing dry pellets of PLA, (b) melting the pellets to form a molten mass at a first desired viscosity value ranging from about 1,000 P to about 5,000 P at about 480° F. at an apparent shear rate of about 55 seconds −1 , (c) increasing the viscosity of the molten mass to a second desired viscosity value or range of values, (d) forming a bubble from the resulting molten mass at a blown up ratio ranging from 1:0.75 to 1.2.0, and (e) collapsing the bubble to form a film.