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US-12624261-B2 - Adhesive for high-frequency dielectric heating, structure, and manufacturing method of structure

US12624261B2US 12624261 B2US12624261 B2US 12624261B2US-12624261-B2

Abstract

A high-frequency dielectric heating adhesive contains a thermoplastic resin, in which the thermoplastic resin contains a styrene copolymer resin, an amount of the styrene copolymer resin contained in the thermoplastic resin is 40% or more by volume and 100% or less by volume, the styrene copolymer resin has a styrene monomer unit content of 10% or more by mass and 90% or less by mass, the high-frequency dielectric heating adhesive has a tensile modulus of 20 MPa or more, and the high-frequency dielectric heating adhesive has a dielectric property (tan δ/ε′r) of 0.005 or more, where tan δ is a dielectric loss tangent at 23 degrees C. and a frequency of 40.68 MHz, and ε′r is a relative dielectric constant at 23 degrees C. and a frequency of 40.68 MHz.

Inventors

  • Koji TSUCHIBUCHI
  • Naoki Taya

Assignees

  • LINTEC CORPORATION

Dates

Publication Date
20260512
Application Date
20210331
Priority Date
20200331

Claims (14)

  1. 1 . A high-frequency dielectric heating adhesive, comprising a thermoplastic resin (A); and a dielectric filler (B) that generates heat when a high-frequency electric field is applied, wherein an amount of the dielectric filler (B) contained in the high-frequency dielectric heating adhesive is 5% or more by volume and 50% or less by volume, the thermoplastic resin (A) comprises a styrene copolymer resin (a1), an amount of the styrene copolymer resin (a1) contained in the thermoplastic resin (A) is 40% or more by volume and 100% or less by volume, the styrene copolymer resin (a1) has a styrene monomer unit content of 10% or more by mass and 90% or less by mass, a total amount of the thermoplastic resin (A) and the dielectric filler (B) contained in the high-frequency dielectric heating adhesive is 80% or more by mass, the high-frequency dielectric heating adhesive has a tensile modulus of 20 MPa or more, and the high-frequency dielectric heating adhesive has a dielectric property (tan δ/ε′r) of 0.005 or more, where tan δ is a dielectric loss tangent at 23 degrees C. and a frequency of 40.68 MHz, and ε′r is a relative dielectric constant at 23 degrees C. and a frequency of 40.68 MHz.
  2. 2 . The high-frequency dielectric heating adhesive according to claim 1 , wherein the dielectric filler (B) is at least one selected from the group consisting of zinc oxide, silicon carbide, titanium oxide, and barium titanate.
  3. 3 . The high-frequency dielectric heating adhesive according to claim 1 , wherein the high-frequency dielectric heating adhesive has a flow start temperature of 80 degrees C. or higher and 250 degrees C. or lower.
  4. 4 . The high-frequency dielectric heating adhesive according to claim 1 , wherein the styrene copolymer resin (a1) is a styrene elastomer.
  5. 5 . The high-frequency dielectric heating adhesive according to claim 1 , wherein the styrene copolymer resin (a1) is a hydrogenated resin.
  6. 6 . The high-frequency dielectric heating adhesive according to claim 1 , wherein the thermoplastic resin (A) further comprises a thermoplastic resin (a2) different from the styrene copolymer resin (a1).
  7. 7 . The high-frequency dielectric heating adhesive according to claim 1 , wherein an amount of the styrene copolymer resin (a1) contained is 20% or more by volume and 98% or less by volume with respect to an entirety of the high-frequency dielectric heating adhesive.
  8. 8 . The high-frequency dielectric heating adhesive according to claim 1 , wherein the high-frequency dielectric heating adhesive is used by applying a high-frequency electric field of 3 MHz or more and 300 MHz or less.
  9. 9 . The high-frequency dielectric heating adhesive according to claim 1 , wherein the high-frequency dielectric heating adhesive is an adhesive for bonding one or more adherends, and at least one of the one or more adherends comprises a resin having an aromatic ring.
  10. 10 . The high-frequency dielectric heating adhesive according to claim 9 , wherein the resin having an aromatic ring is a styrene resin.
  11. 11 . The high-frequency dielectric heating adhesive according to claim 1 , wherein the high-frequency dielectric heating adhesive is an adhesive sheet.
  12. 12 . The high-frequency dielectric heating adhesive according to claim 11 , wherein the adhesive sheet has a thickness of 5 μm or more and 2,000 μm or less.
  13. 13 . A structure comprising one or more adherends bonded using the high-frequency dielectric heating adhesive according to claim 1 .
  14. 14 . A method for producing a structure, comprising: disposing the high-frequency dielectric heating adhesive according to claim 1 on one or more adherends; and applying a high-frequency electric field of 3 MHz or more and 300 MHz or less to the high-frequency dielectric heating adhesive to bond the adherends.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This patent application is the U.S. National Phase under 35 U.S.C. § 371 of International Application No. PCT/JP2021/014034, filed on Mar. 31, 2021, which claims the benefit of Japanese Patent Application No. 2020-063291, dated Mar. 31, 2020, Japanese Patent Application No. 2020-063433, dated Mar. 31, 2020, and Japanese Patent Application No. 2020-202036, dated Dec. 4, 2020, the entire contents of each are hereby incorporated by reference in their entirety. TECHNICAL FIELD The present invention relates to a high-frequency dielectric heating adhesive, a structure, and a method for producing a structure. BACKGROUND ART As a method for producing a laminate by bonding multiple adherends to each other, for example, a method has been reported in which an adhesive is interposed between adherends and then subjected to, for example, dielectric heating treatment, induction heating treatment, ultrasonic welding treatment, or laser welding treatment. For example, Patent Literature 1 discloses that a surface sheet including a film layer containing silica and a resin blend of a polyolefin resin and a styrene copolymer resin is subjected to thermal fusion bonding. This film layer described in Patent Literature 1 contains the resin blend containing 50 parts by mass of the styrene copolymer resin and 5 parts by mass of silica with respect to 100 parts by mass of the polyolefin resin. CITATION LIST Patent Literature Patent Literature 1: JP 2004-148839 A SUMMARY OF THE INVENTION Problems to be Solved by the Invention In the surface sheet disclosed in Patent Literature 1, the resin blend contained in the film layer has a low styrene copolymer resin content. Thus, for example, when the surface sheet disclosed in Patent Literature 1 is bonded to an adherend containing a styrene resin, it is difficult to bond the surface sheet and the adherend in a short time, and the adhesiveness of the surface sheet to the adherend is not sufficient. Further, conventional adhesives containing styrene resins have room for further improvement in strength characteristics, such as fracture toughness. An object of the invention is to provide a high-frequency dielectric heating adhesive containing a styrene resin, the high-frequency dielectric heating adhesive being capable of bonding in a short time and having improved fracture toughness, a structure including an adherend bonded using the high-frequency dielectric heating adhesive, and a method for producing the structure. Problems to be Solved by the Invention An aspect of the invention provides a high-frequency dielectric heating adhesive containing a thermoplastic resin (A), in which the thermoplastic resin (A) contains a styrene copolymer resin (a1), an amount of the styrene copolymer resin (a1) contained in the thermoplastic resin (A) is 40% or more by volume and 100% or less by volume, the styrene copolymer resin (a1) has a styrene monomer unit content of 10% or more by mass and 90% or less by mass, the high-frequency dielectric heating adhesive has a tensile modulus of 20 MPa or more, and the high-frequency dielectric heating adhesive has a dielectric property (tan δ/ε′r) of 0.005 or more, where tan δ is a dielectric loss tangent at 23 degrees C. and a frequency of 40.68 MHz, andε′r is a relative dielectric constant at 23 degrees C. and a frequency of 40.68 MHz. The high-frequency dielectric heating adhesive according to the aspect of the invention preferably further contains a dielectric filler (B) that generates heat when a high-frequency electric field is applied. In the high-frequency dielectric heating adhesive according to the aspect of the invention, the dielectric filler (B) is preferably at least one selected from the group consisting of zinc oxide, silicon carbide, titanium oxide, and barium titanate. In the high-frequency dielectric heating adhesive according to the aspect of the invention, the high-frequency dielectric heating adhesive preferably has a flow start temperature of 80 degrees C. or higher and 250 degrees C. or lower. In the high-frequency dielectric heating adhesive according to the aspect of the invention, the styrene copolymer resin (a1) is preferably a styrene elastomer. In the high-frequency dielectric heating adhesive according to the aspect of the invention, the styrene copolymer resin (a1) is preferably a hydrogenated resin. In the high-frequency dielectric heating adhesive according to the aspect of the invention, preferably, the thermoplastic resin (A) further contains a thermoplastic resin (a2) different from the styrene copolymer resin (a1). In the high-frequency dielectric heating adhesive according to the aspect of the invention, an amount of the styrene copolymer resin (a1) contained is preferably 20% or more by volume and 98% or less by volume with respect to an entirety of the high-frequency dielectric heating adhesive. In the high-frequency dielectric heating adhesive according to an aspect of the invention, the