Patent ID: 6797458
Filing Date: 2004-09-28
Classification: C08G,G03C,Y10T

Abstract:
A biaxially stretched, semicrystalline multilayer film base comprising at least two layers:a) a first layer of a first PET-base polyester material comprising one or more polyester resins; b) adjacent to at least one side of the first layer a second layer of a second PET-based polyester material comprising one or more polyester resins, in which material the total level of repeat units derived from 1,4-cyclohexane dimethanol is greater than the corresponding level in the first layer, based on total glycol component in the material, and wherein the difference in the level of 1,4-cyclohexane dimethanol between the first and the second layer is less than 50 mol % based on the total glycol component; wherein total level of repeat units derived from 1,4-cyclohexane dimethanol in the first PET-based polyester material is at least 3.5 mol % based on total glycol component in the material, except that when said second layer has a level of repeat units derived from 1,4-cyclohexane dimethanol that is between 3.5 and 25 mol %, based on total glycol component in the material, then the first layer can have less than 3.5 mol % 1,4-cyclohexane dimethanol, or none, based on total glycol component; wherein at least the polyester material in the second layer is semi-crystalline; wherein the total thickness of said film base is 50 to 180 &mgr;m; wherein the ratio of the thickness of the second layer to the thickness of the entire film base is 0.05 to 0.40; and wherein the cutting index of said multilayer film base is less than 4.2.