| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a laminated material for a paper container, which comprises a paper layer and a PET resin layer and in which the low-temperature heat sealability is ensured by modifying an inexpensive PET resin and the extrusion properties when being extruded/layered onto the paper layer are improved by heightening the viscosity or tension in melting. <P>SOLUTION: A chain extender is added to the PET resin having 0.55-0.7 dL/g intrinsic viscosity, to charge the PET resin into an extruder having two or more vent holes. In a state where the PET resin is heated/melted, the PET resin is sucked/deaerated through the vent holes in high vacuum of -750 mmHg or lower. Thereafter, the PET resin is extruded onto the paper layer to laminate the PET resin layer thereon. Immediately after the PET resin layer is laminated, a PET resin layer surface is cooled quickly by a cooling roller. The chrystalline portion of the PET resin layer is expressed by formulae: the crystalline portion (%)=100×(a melting calorie per mol-cooling crystallization calorie per mol)/äa melting calorie per mol of a perfect crystal PET (26.9 KJ)}; and a noncrystalline portion (%)=100-the crystalline portion; wherein the crystalline portion is <15% and the noncrystalline portion is ≥85%. <P>COPYRIGHT: (C)2012,JPO&INPIT |
