Search

EP-4742835-A2 - DIELECTRIC-HEATING BONDING FILM AND BONDING METHOD USING DIELECTRIC-HEATING BONDING FILM

EP4742835A2EP 4742835 A2EP4742835 A2EP 4742835A2EP-4742835-A2

Abstract

A dielectric welding film capable of achieving a tight welding through a short period of dielectric heating, and a welding method using the dielectric welding film are provided. The dielectric welding film is configured to weld a pair of adherends of the same material or different materials through dielectric heating, the dielectric welding film including a thermoplastic resin as an A component and a dielectric filler as a B component and satisfying the 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.

Inventors

  • ISHIKAWA, MASAKAZU

Assignees

  • LINTEC CORPORATION

Dates

Publication Date
20260513
Application Date
20171018

Claims (5)

  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 isa polyolefin resin, the polyolefin resin comprising one of or a combination of resins selected from a homopolymer resin and α-olefin resin of a copolymer of ethylene, propylene, butene, hexene, octene, and 4-methylpentene, the homopolymer resin being selected from the group consisting of polyethylene, polybutene and polymethylpentene, the B component is zinc oxide, wherein a median particle diameter D50 of the B component measured in accordance with JIS Z 8819-2 (2001) is in a range from 1 to 30 µm, a content of the B component is in a range from 30 to 600 parts by mass with respect to 100 parts by mass of the A component, a dielectric property (tanδ/ε') defined by dividing a dissipation factor tanδ 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 dielectric welding film satisfying 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 50 to 300 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 a polyolefin resin, the polyolefin resin comprising one of or a combination of resins selected from a homopolymer resin and α-olefin resin of a copolymer of ethylene, propylene, butene, hexene, octene, and 4-methylpentene, the homopolymer resin being selected from the group consisting of polyethylene, polybutene and polymethylpentene, the B component is zinc oxide, wherein a median particle diameter D50 of the B component measured in accordance with JIS Z 8819-2 (2001) is in a range from 1 to 30 µm, a content of the B component is in a range from 30 to 600 parts by mass with respect to 100 parts by mass of the A component, the dielectric welding film satisfying 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 (tanδ/ε') defined by dividing a dissipation factor tanδ 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 any one of claims 3 or 4, wherein a content of the B component is in a range from 50 to 300 parts by mass with respect to 100 parts by mass of a content of the A component.

Description

TECHNICAL FIELD The present invention relates to a dielectric welding film, and a welding method using the dielectric welding film. Specifically, the present invention relates to a dielectric welding film, which is usable for adherends of different types and is capable of providing a large adhesivity through a relatively short period of dielectric heating (sometimes referred to as high-frequency dielectric heating hereinafter), and a welding method using the dielectric welding film. BACKGROUND ART In order to weld a plurality of typically hard-to-bond adherends (i.e. difficult to be bonded), it has been recently proposed that, for instance, a welding process such as dielectric heating, induction heating, ultrasonic welding or laser welding is performed with an adhesive produced by blending a heat-generating material in a predetermined resin. According to a proposed welding method by dielectric heating among the above, an adhesive blended with carbon black (CB), silicon carbide (SiC), or the like is interposed between a plurality of adherends and dielectric heating at a frequency of 28 or 40 MHz or microwave heating is applied to weld the plurality of adherends (see Patent Literatures 1 and 2). According to another proposed welding method by the dielectric heating, polyolefin resin is blended with a ferroelectric material and a carbon compound, a conductive material or the like to prepare an adhesive with a dissipation factor (tanδ) of 0.03 or more, and the adhesive is interposed between a plurality of adherends to adhere the adherends through dielectric heating at a frequency of 40 MHz (see Patent Literatures 3 and 4). According to still another proposed related art, an adhesive composition for dielectric heating is produced by adding a dielectric heating medium to an adhesive compatible with a plurality of adherends (base materials) to be bonded. The adhesion layer composition for dielectric heating satisfies a formula: C × {(tanδ) / ε'}1/2 ≥ d, where ε' represents specific permittivity, tanδ represents a dissipation factor, d (mm) represents a total thickness of the base materials to be bonded, and the coefficient C is in a range from 78 to 85 (see Patent Literature 5). In a further related art, a modified polyolefin resin composition for heat welding and a sheet thereof are disclosed that are designed to provide excellent weldability to a hard-to-bond base material (see Patent Literature 6). More specifically, the modified polyolefin resin composition is provided by grafting (b) an epoxy-group containing vinyl monomer, (c) an aromatic vinyl monomer and (d) (meth)acrylate polymer to (a) a polyolefin resin. The modified polyolefin resin composition exhibits heat of fusion ranging from 1 to 100 J/g and melting point ranging from 80 to 190 degrees C. CITATION LIST PATENT LITERATURE(S) Patent Literature 1JP 2010-6908 A (claims etc.)Patent Literature 2JP 2008-156510 A (claims etc.)Patent Literature 3JP 2003-238745 A (claims etc.)Patent Literature 4JP 2003-193009 A (claims etc.)Patent Literature 5JP 2014-37489 A (claims etc.)Patent Literature 6JP 2009-126922 A (claims etc.) SUMMARY OF THE INVENTION PROBLEM(S) TO BE SOLVED BY THE INVENTION However, the dielectric heating disclosed in Patent Literatures 1 and 2, in which a considerable amount of the conductive material such as carbon black (CB) is blended in the adhesive to prepare the adhesion layer composition, is likely to cause electric breakdown during the dielectric heating to carbonize a adhered portion and/or the adherends. In addition, vertical alignment of the adherends is difficult due to the color of the resultant adhesion layer composition (i.e. perfectly opaque black (visible light transmissivity: 0%)). Accordingly, it is difficult to apply the dielectric heating at an accurate position or adhere correct portions. The dielectric heating disclosed in Patent Literatures 3 and 4 is also likely to cause electric breakdown during the dielectric heating process due to the considerable amount of the conductive material (e.g. metal and carbide compound) added in the adhesive resin composition. In addition, vertical alignment of the plurality of adherends is difficult due to the perfect opacity of the resultant adhesion resin composition (visible light transmissivity: 0%). Accordingly, it is difficult to apply the dielectric heating at an accurate position. The adhesiveness of the adhesion layer composition for dielectric heating disclosed in Patent Literature 5 is affected by a total thickness of base materials to be adhered, so that the type of usable adherend is likely to be excessively limited. In addition, at least 40 to 70 seconds of dielectric heating, which is considerably long in terms of practical use, has to be applied in order to ensure sufficient adhesion strength and thus the adhesion layer composition is economically disadvantageous. Moreover, none of Patent Literatures 1 to 5 discloses or suggests the adhesion layer composition for dielectric