| 摘要 |
PROBLEM TO BE SOLVED: To obtain a composition which can give a biodegradable product having sufficiently practicable transparency and flexibility and excellent long- term stability by formulating a plasticizer to a polylactate irradiated with light from a source which emit ultraviolet light having a specified wavelength and a specified intensity. SOLUTION: This composition is prepared by adding a plasticizer to a polylactic acid irradiated with light from a source which emits ultraviolet light having a wavelength of 400 nm or shorter, desirably, 250-370 nm and an intensity of 120 W/cm2 or above, desirably, 120-300 mW/cm2. This can be produced by irradiating a polylactic acid with light from the above source and adding a plasticizer to the irradiated polylactic acid or by irradiating a polylactic acid containing a plasticizer with light from the above source. The plasticized polylactic acid can be produced by varying the formulation amount of the plasticizer added according to the optical purity of the starting polylactic acid. A high-optical-purity plasticized polylactate is molded into a film, a container, or the like, and a low-optical-purity plasticized polylactate gives an adhesive, a pressure-sensitive adhesive, or the like. |
