Welded film and method of producing same

A welded film, comprising:

• a first thermoplastic resin film;
• a second thermoplastic resin film;
• and
• a thermoplastic resin film for connection disposed so as to span between the first thermoplastic resin film and the second thermoplastic resin film, wherein:
• the first thermoplastic resin film and the thermoplastic resin film for connection are welded at a first welded portion, and the second thermoplastic resin film and the thermoplastic resin film for connection are welded at a second welded portion, and
• a positional relationship between the first thermoplastic resin film or the second thermoplastic resin film, and the first welded portion or the second welded portion, satisfies at least one selected from the group consisting of the following (i) and (ii):
• (i) a minimum distance between an end portion of the first thermoplastic resin film at a side of the second thermoplastic resin film and the first welded portion is 0.5 mm or more;
• and
• (ii) a minimum distance between an end portion of the second thermoplastic resin film at a side of the first thermoplastic resin film and the second welded portion is 0.5 mm or more.

A welded film, comprising:

• a first thermoplastic resin film;
• a second thermoplastic resin film;
• and
• a thermoplastic resin film for connection disposed so as to span between the first thermoplastic resin film and the second thermoplastic resin film, wherein:
• the first thermoplastic resin film and the thermoplastic resin film for connection are welded at a first welded portion, and the second thermoplastic resin film and the thermoplastic resin film for connection are welded at a second welded portion, and
• a positional relationship between the first welded portion and the second welded portion satisfies at least one selected from the group consisting of 0<(L1b/L1a)<0.99 and 0<(L2b/L2a)<0.99,
• wherein:
• L1b represents a width of the first welded portion,
• L1a represents a total length obtained by adding a minimum distance from an end portion of the first thermoplastic resin film, at a side of the second thermoplastic resin film, to the first welded portion, to the width L1b of the first welded portion,
• L2b represents a width of the second welded portion, and
• L2a represents a total length obtained by adding a minimum distance from an end portion of the second thermoplastic resin film, at a side of the first thermoplastic resin film, to the second welded portion, to the width L2b of the second welded portion.

A method of producing a welded film, the method comprising:

• preparing a temporary arrangement body in which a thermoplastic resin film for connection spans between a first thermoplastic resin film and a second thermoplastic resin film;
• and
• performing thermocompression bonding on the temporary arrangement body with a first heater disposed outside the thermoplastic resin film for connection and a second heater disposed outside the first thermoplastic resin film and the second thermoplastic resin film, to form a first welded portion at which the first thermoplastic resin film and the thermoplastic resin film for connection are welded to each other and a second welded portion at which the second thermoplastic resin film and the thermoplastic resin film for connection are welded to each other,
• wherein at least one selected from the group consisting of the first heater and the second heater is configured not to come into contact with a portion between the first welded portion and the second welded portion during the thermocompression bonding.