Dielectric-heating bonding film and bonding method using dielectric-heating bonding film

A welding method using a dielectric welding film configured to weld a pair of adherends of the same material or different materials through dielectric heating, the dielectric welding film comprising a thermoplastic resin as an A component and a dielectric filler as a B component, wherein

• the A component is at least one thermoplastic resin selected from the group consisting of a polyolefin resin, an olefin thermoplastic elastomer, a polyamide resin, a polyvinyl acetate resin, a polyacetal resin, and a polyester resin, wherein when the A component contains a polyolefin resin, the polyolefin resin is one of or a combination of resins selected from a homopolymer resin including polyethylene, polypropylene, polybutene and polymethylpentene, and a α-olefin resin of a copolymer of ethylene, propylene, butene, hexene, octene, and 4-methylpentene,
• the B component is zinc oxide,
• a mean particle size of the B component measured in accordance with JIS Z 8819-2 (2001) is in a range from 1 to 30 μm, and
• the dielectric welding film satisfies conditions (i) to (iii):
• (i) a melting point or softening point measured in accordance with JIS K 7121 (1987) is in a range from 80 to 200 degrees C.;
• (ii) heat of fusion measured in accordance with JIS K 7121 (1987) is in a range from 1 to 80 J/g;
• and
• (iii) a dielectric property (tan δ/ε′) defined by dividing a dissipation factor tan δ of the dielectric welding film by a permittivity ε′ of the dielectric welding film at 23 degrees C. and 40 MHz frequency is 0.005 or more, the method comprising steps (1) and (2):
• (1) holding the dielectric welding film between the pair of adherends;
• and
• (2) applying the dielectric heating on the dielectric welding film held between the pair of adherends with a dielectric heater by applying a high-frequency wave of 1 to 100 MHz frequency.