| 摘要 |
PROBLEM TO BE SOLVED: To provide a package, in which an angular projection or a hole is prevented from being formed at the four corners of the package by a tight packaging utilizing a thermal shrinkage, by a method wherein an inner layer comprising a straight-chain low density polyethylene and both outer layers comprising a propylene resin are provided so that a specific layer thickness ratio is provided between the layers and air discharge holes each having a specific diameter are formed at a specific pitch. SOLUTION: A low density straight-chain polyethylene is prepared by copolymerizingα-olefin such as ethylene and propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene and by introducing short chain branches to achieve low density, which is used to form an inner layer. And such a resin as a polymer of single propylene which has heat-shrinkable properties obtained by a stretching treatment is used in both outer layers, and the outer layer-inner layer-outer layer ratio in thickness is 1:8:1-1:1:1 and air discharge holes having diameter of 0.2-0.6mm are formed at a pitch of 20-80mm in the flow direction and width direction of the film.
|
