Easy-to-tear, unstretched resin film and laminate film for packaging material using the same

An easy-to-tear, unstretched resin film consisting of a blend of a polyethylene terephthalate-based resin and a second resin having a difference in solubility parameter (SP) value from the polyethylene terephthalate-based resin of 1.1 to 4.0 (cal/cm3)0.5,

• wherein the second resin is a cycloolefin copolymer or polymethyl methacrylate;
• wherein the second resin is dispersed in a particulate state in the polyethylene terephthalate-based resin and the average aspect ratio of the particles is 1 to 1.76;
• wherein the film has a tear strength in the longitudinal direction of 0.25 N or lower and a tear strength in the transverse direction of 0.25 N or lower;
• and
• wherein the tear strength in the longitudinal direction and the tear strength in the transverse direction are measured according to the Trouser method using a test rate of 200 mm/minute at a temperature of 25° C.;
• wherein the polyethylene terephthalate-based resin is an isophthalic acid-modified polyethylene terephthalate resin having a copolymerization ratio of isophthalic acid component of 1 mol % to 5 mol %, based on the whole dicarboxylic acid component of the isophthalic acid-modified polyethylene terephthalate resin;
• wherein in the blend, the proportion of the polyethylene terephthalate-based resin is 65% to 75% by weight and the proportion of the second resin is 35% to 25% by weight.