| 摘要 |
PURPOSE: A white film is provided to ensure small amount of oligomer extract, excellent masking property and whiteness, and good workability and to enable use for food packaging, insulation, and solar cell back sheet. CONSTITUTION: A method for preparing a white film comprises the steps of: (i) preparing a polyester resin with inherent viscosity of 0.65~0.90 and oligomer content of 0.5% or less; (ii) manufacturing a master batch in which an oligomer content within a polyester resin is less than 0.5% and a melting viscosity in a range that a shear rate after melting at 280 °Cfor 5 minutes is 100~5,000 1/s is 500~3,000 poise; (iii) mixing the polyester resin and master batch to prepare a sheet; (iv) monoaxially or biaxially orienting the sheet; (v) heat-treating the oriented film; and (vi) heat-setting the heat-treated film. |
