PURPOSE: To prepare a heat-sealing agent suitable for the heat-sealing of a polypropylene molded article and a lid made of aluminum foil or polyethylene terephthalate film, by mixing a linear copolyester resin and a chlorinated isotactic polypropylene resin.

CONSTITUTION: A heat-sealing agent obtained by mixing (A) 10W70pts.wt. of a chlorinated isotactic polypropylene resin (pref. a crystalline resin containing 10W 45% of chlorine) and (B) 30W90pts.wt. of a linear copolyester resin (wherein 95W50mol% of the acid component is terephthalic acid residue and 20W70mol% of the glycol component is ethylene glycol residue) in an organic solvent. Addition of 1W20pts.wt. of a carboxylated polypropylene resin (acid value; 0.5W100 mgKOH/g) improves the blocking resistance, etc. The heat-sealing agent is pref. applied to ≤20μ thickness.

EFFECT: A transparent, easily openable container can be obtained by using a PET film as a base of the lid.