| 摘要 |
PROBLEM TO BE SOLVED: To attain a practically nonproblematic bonding strength and excellent appearance free from crystallization whitening by applying a mixed organic solvent containing an alcoholic organic solvent to each polyester sheet having a copolyester layer soluble or swellable in an organic solvent on at least either surface and bonding the sheets together. SOLUTION: A mixed organic solvent containing 5-50 vol.% alcoholic organic solvent such as methanol, ethanol, isopropyl alcohol, or benzyl alcohol is applied to the copolyester layer of each polyester sheet having a copolyester layer being soluble or swellable in an organic solvent and desirably having a thickness of 5μm or above on at least one surface, and the sheets are bonded together. The copolyester is desirably one obtained by replacing 15-35 mol.% of each of the acid component of a polyethylene terephthalate based on terephthalic acid and ethylene glycol and its ethylene glycol component by isophthalic acid and cyclohexane dimethanol, neopentyl glycol, or the like.
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