TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The amorphous polyester resin is the resin being prepared by copolymerizing components including the acid component comprising isophthalic acid, oxyethoxy benzoic acid, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid and/or the ester-forming derivative, the diol component comprises propyleneglycol, trimethyleneglycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-bisoxyethoxybenzene, bisphenol, polyoxyethyleneglycol, and/or neopentylglycol; and is present at 10-20 mole% in the polyethyleneterephthalate structure that is prepared by the polymerization of terephthalic acid and ethylene glycol. The masterbatch includes 50-150 parts by weight of barium sulfate based on the 100 parts by weight of amorphous polyester resin. The polyester resin is polyethyleneterephthalate. Preferred Method: The mixing of the polyester resin with the masterbatch and then the extruding of it after the melt-mixing, the sheet includes 10-100 parts by weight of masterbatch based on the 100 parts by weight of polyester resin. EXAMPLE - Masterbatch (prepared by amorphous polyester resin (5 parts by weight) was added to the polymerization reaction of terephthalic acid and ethylene glycol, barium sulfate (100 parts by weight), were added to the twinscrew extruder hopper and worked up to give masterbatch) (35 parts of weight) and oligomer content (0.4%) were mixed, put to the extruder, melted, then extruded at T-die, to prepare the sheet having the surface temperature of 30 degrees C. The prepared polyethyleneterephthalate sheet was drawn three times in the machine direction at 105 degrees C, and cooled down, then drawn more 3.5 times in the transversal direction by warming up at 130 degrees C higher than machine direction drawing temperature, the heat-treatment was carried out at 220 degrees C in the heat-treatment zone of tenter of more than 5 pairs, then the film was 5% relaxed to the length of transversal direction at the temperature of 210 degrees C, and cooled down to give the biaxially drawn white film having the thickness of 188 mu m.