| abstract |
An inexpensive stretched polyester film which has satisfactory tearableness and twistability while retaining intact heat resistance, cold resistance, moisture resistance, transparency, aroma retention, and other properties. It is useful as a packaging film or a film for tapes, or in stick packaging, PTP packaging, drug packaging, or folding packaging, or as a lid material or an opening for beverage packs. Also provided is a process for producing a film by mixing two or more raw polyester resin materials differing in melting point or melting temperature and extruding the mixture, the process comprising separately introducing the raw materials into respective extruders, melting the raw materials, feeding the materials in a molten state to one mixer, mixing the materials, extruding the mixture to obtain a sheet, stretching the sheet at least uniaxially, and then heating the sheet at a temperature not lower than the temperature lower by 3°C than the melting point or melting temperature of the raw resin material lowest in melting point or melting temperature. Thus, a polyester resin film is produced which is excellent in suitability for tearing by hand and twistability. |