| 摘要 |
<p>PURPOSE: To improve the heat-bonding property of a film to obviate the need of providing a bonding layer between the film and a cover material and prevent an accumulation of the film in the natural environment after it is discarded, by making the film of a material whose major component is a lactic acid polymer. CONSTITUTION: A film is made of a material whose major component is a lactic acid polymer. The lactic acid polymer to be used is either poly (L-lactic acid) whose building unit consists of only L-lactic acid, poly (D-lactic acid) whose building unit consists of only D-lactic acid or poly (DL-lactic acid) in which L-lactic acid and D-lactic acid building units exist at various ratios. The molecular weight of lactic acid polymer has an influence on workability, strength and decomposition property of the film for blister package. Low molecular weight causes a decline in strength of the film obtained and so the film is may break by tensile force while the film is in use. In addition, it also causes an increase in decomposition speed. By contrast, high molecular weight causes a decline in workability, resulting in a difficulty in film making. Therefore, the molecular weight of lactic acid polymer to be used is at least about 100,000 and not higher than 300,000.</p> |
