Patented is a method of producing a laminated polyolefin film with three or more layers including two outer layers. The method involves several steps, including preparing an outer-layer forming material by causing olefin resin to contain a non-ionic surfactant and salt of organic sulfonic acid in a total amount of 0.05-3 weight % and a weight ratio of 20/80-99/1.
The next step is producing the laminated polyolefin film by using olefin resin. The outer-layer forms a material in a coextrusion method and forms at least one of the outer layers from the outer-layer forming material. The non-ionic surfactant comprises one or more selected from the group consisting of partial esters of polyoles with valence 3-6 and aliphatic monocarboxylic acid with 6-22 carbon atoms, alkyl diethanol amines with ailcyl group with 6-22 carbon atoms and alkyl diethanol amides with acyl group with 6-22 carbon atoms.
The salt of organic sulfonic acid comprises one or more selected from the group consisting of alkali salts of alkyl sulfonic acid with alkyl group with 6-22 carbon atoms, alkali salts of alkyl aryl sulfonic acid with alkyl group with 2-22 carbon atoms and alkali salts of sulfo fatty acid ester with alkyl group with 2-22 carbon atoms.