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JP-2026075293-A - Laminated piezoelectric film and method for manufacturing the same

JP2026075293AJP 2026075293 AJP2026075293 AJP 2026075293AJP-2026075293-A

Abstract

[Problem] To provide a laminated piezoelectric film that is difficult to peel off the adhesive film. [Solution] A laminated piezoelectric film comprising: a fluorine-based piezoelectric film having a piezoelectric constant d33 of 10.0 pC/N or more and 40.0 pC/N or less, and a tensile strength in the slow phase axis direction determined from the in-plane birefringence of the film as defined in JIS C 5876-1:2009 of 50 N to 1600 N; an adhesive film; and an adhesive layer for bonding the fluorine-based piezoelectric film and the adhesive film, having a glass transition temperature of -100°C or more and 0°C or less as measured in accordance with JIS K 6240:2001. [Selection Diagram] Figure 1

Inventors

  • 松下 祐樹
  • 三枝 孝拓

Assignees

  • 株式会社クレハ

Dates

Publication Date
20260508
Application Date
20241022

Claims (7)

  1. A fluorine-based piezoelectric film having a piezoelectric constant d33 of 10.0 pC/N or more and 40.0 pC/N or less, and a tensile strength in the slow phase axis direction determined from the in-plane birefringence of the film as defined in JIS C 5876-1:2009 of 50 N or more and 1600 N or less, Adhesive film and An adhesive layer for bonding the fluorine-based piezoelectric film and the adhesive film, wherein the adhesive layer has a glass transition temperature of -100°C or higher and 0°C or lower, as measured in accordance with JIS K 6240:2001. A laminated piezoelectric film having the following characteristics.
  2. The aforementioned fluorine-based piezoelectric film mainly consists of vinylidene fluoride resin. The laminated piezoelectric film according to claim 1.
  3. The laminated piezoelectric film according to claim 1, wherein the thickness of the fluorine-based piezoelectric film is 10 μm or more and 350 μm or less.
  4. The aforementioned adhesive film has a conductive layer having a surface resistivity of 1.0 × 10⁴ Ω/sq. or less. The laminated piezoelectric film according to claim 1.
  5. The peel strength between the fluorine-based piezoelectric film and the conductive layer, measured in accordance with JIS K 6854-2:1999, is 2 N/15 mm or more and 40 N/15 mm or less. The laminated piezoelectric film according to claim 4.
  6. A step of applying an adhesive to the release surface of a release film and drying it to form an adhesive layer having a glass transition temperature of -100°C or higher and 0°C or lower, as measured in accordance with JIS K 6240:2001, The process includes a step of laminating a fluorine-based piezoelectric film, having a piezoelectric constant d33 of 10.0 pC/N or more and 40.0 pC/N or less, and a tensile strength in the slow axis direction determined from the in-plane birefringence of the film as defined in JIS C 5876-1:2009 of 50 N or more and 1600 N or less, to the release film with the adhesive layer, A method for manufacturing a laminated piezoelectric film according to claim 1.
  7. The steps include peeling the release film from the laminated piezoelectric film and transferring the adhesive layer to the fluorine-based piezoelectric film, The process includes a step of laminating an electrode film having a conductive layer with a surface resistivity of 1.0 × 10⁴ Ω/sq. or less to the fluorine-based piezoelectric film using the adhesive layer. A method for manufacturing a laminated piezoelectric film according to claim 6.

Description

This invention relates to a laminated piezoelectric film and a method for manufacturing the same. Polylactic acid films and fluoropolymer films are known to exhibit piezoelectric properties through stretching and polarization treatments. In particular, flexible piezoelectric films prepared from polymer films are widely used in piezoelectric sensors for small portable devices. Piezoelectric films are used with thin-film electrodes to detect the charge generated by pressure, and protective films to prevent surface scratches. Furthermore, fluoropolymer films are sometimes used as laminated piezoelectric films with electrodes and protective films laminated on top. Typically, piezoelectric films are stored and transported in rolls. During transport, vibrations can cause electric charge to accumulate on the film's surface. This accumulated charge can attract foreign matter or cause scratches on the film's surface. Therefore, a removable protective film is often laminated to the surface of piezoelectric films during storage and transport. Piezoelectric films are also sometimes used with other layers, such as electrode layers, laminated onto them. To laminate other layers onto a piezoelectric film, an adhesive layer is sometimes used. For example, Patent Document 1 describes a method of bonding a release film coated with an adhesive to the surface of a polylactic acid-based piezoelectric film. Patent Document 1 also describes a method in which the release film is peeled off from the laminate produced in this way to expose the adhesive, and another film is then attached to the exposed adhesive. International Publication No. 2016/140110 Figure 1 is a schematic diagram showing the manufacturing process of a laminated piezoelectric film (first laminated film) according to one embodiment of the present invention.Figure 2 is a magnified view of area X shown in Figure 1, and is a schematic diagram illustrating how adhesive is applied to the release film being transported.Figure 3 is a magnified view of region Y shown in Figure 1, and is a schematic diagram illustrating how an adhesive layer is formed on the release film as it is being transported.Figure 4 is a magnified view of region Z shown in Figure 1, and is a schematic diagram illustrating how the piezoelectric film is bonded to the release film by the adhesive layer.Figure 5 is a schematic diagram showing the manufacturing process of a laminated piezoelectric film (second laminated film) according to another embodiment of the present invention.Figure 6 is a magnified view of region V shown in Figure 5, and is a schematic diagram illustrating the process of peeling the release film from the laminated piezoelectric film and transferring the adhesive layer to the fluorine-based piezoelectric film.Figure 7 is a partially enlarged view of region W shown in Figure 5, and is a schematic diagram illustrating how the electrode film is bonded to the fluorine-based piezoelectric film onto which the adhesive layer has been transferred. [Laminated piezoelectric film] One embodiment of the present invention relates to a laminated piezoelectric film having a fluorine-based piezoelectric film, a film to be adhered to, and an adhesive layer for bonding the fluorine-based piezoelectric film and the film to be adhered to. (Fluorine-based piezoelectric film) A fluorine-based piezoelectric film may contain fluororesin as its main component. Fluororesin is a resin obtained by polymerizing monomers made of fluorine-containing olefins, and a fluorine-based piezoelectric film containing fluororesin as its main component means that the proportion of fluororesin to the total mass of the piezoelectric film is 50% by mass or more. The proportion of fluororesin content to the total mass of the piezoelectric film is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less. Fluororesins can be homopolymers or copolymers obtained by polymerizing tetrafluoroethylene or vinylidene fluoride. Examples of fluororesins obtained by polymerizing tetrafluoroethylene include copolymers of tetrafluoroethylene with ethylene, perfluoroalkyl vinyl ethers, vinylidene fluoride, 1-chloro-1-fluoroethylene, chlorotrifluoroethylene, and hexafluoropropylene. Examples of fluororesins obtained by polymerizing vinylidene fluoride include homopolymers of vinylidene fluoride, as well as copolymers of vinylidene fluoride with 1-chloro-1-fluoroethylene, 1-chloro-2-fluoroethylene, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, tetrafluoropropene, hexafluoropropylene, and perfluoroalkyl vinyl ethers. Of these, from the viewpoint of facilitating polarization of the fluororesin film used as the piezoelectric film material, fluororesins obtained by polymerizing vinylidene fluoride are preferred. More preferably, these are homopolymers of vinylidene fluoride, copolymers of vinylidene