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

1. 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,

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, and

the dielectric welding film satisfies conditions (i) and (ii):

(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.; and

(ii) heat of fusion measured in accordance with JIS K 7121 (1987) is in a range from 1 to 80 J/g.

2. The dielectric welding film according to claim 1 , wherein a content of the B component is in a range from 5 to 800 parts by mass with respect to 100 parts by mass of the A component.

3. 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.

4. The welding method according to claim 3 , wherein in the step (2), the high-frequency wave is applied at a high-frequency output ranging from 0.1 to 20 kW and a high-frequency-wave application time of 1 second or more and less than 40 seconds.

5. The welding method according to claim 3 , wherein a content of the B component is in a range from 5 to 800 parts by mass with respect to 100 parts by mass of a content of the A component.