Search

JP-2026075290-A - Manufacturing method for laminated piezoelectric film

JP2026075290AJP 2026075290 AJP2026075290 AJP 2026075290AJP-2026075290-A

Abstract

[Problem] To provide a method for manufacturing a laminated piezoelectric film that suppresses the generation of water droplets due to condensation on the guide rolls that transport the adhesive film after the adhesive has been applied and until it dries. [Solution] A method for manufacturing a laminated piezoelectric film, comprising the steps of applying an adhesive to a film to be adhered using a coating device, drying the adhesive applied to the film to be adhered in a dryer set to 40°C or higher and 80°C or lower to form an adhesive layer with a thickness of 10 μm or higher and 50 μm or lower, and adhering a piezoelectric film to the film to be adhered using the adhesive layer, all performed while transporting the film to be adhered. The guide rolls that are placed between the application of the adhesive and drying in the dryer and transport the film to be adhered include guide rolls whose surface temperature is between the dew point and 80°C at the location where the coating device is installed. [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 (10)

  1. A step of applying adhesive to the film to be adhered using a coating device, The process involves drying the adhesive applied to the aforementioned film in a dryer set to a temperature of 40°C to 80°C to form an adhesive layer with a thickness of 10 μm to 50 μm. The process involves adhering a piezoelectric film to the film to be adhered using the adhesive layer, A method for manufacturing a laminated piezoelectric film, which is carried out while conveying the aforementioned adhesive film, The guide rolls, which are positioned to transport the film to be adhered after the adhesive has been applied and before it is dried in the dryer, include a temperature-controlled roll whose surface temperature is adjusted to be between the dew point and 80°C at the location where the coating device is installed. A method for manufacturing laminated piezoelectric films.
  2. The temperature control roll has a thermal conductivity of 0.03 W/(m·K) or more and 5.0 W/(m·K) or less as measured on its surface. A method for manufacturing a laminated piezoelectric film according to claim 1.
  3. The temperature control roll is positioned in a region within the dryer where the surface temperature of the film to be adhered is equal to or greater than the dew point. A method for manufacturing a laminated piezoelectric film according to claim 1.
  4. The temperature control roll is positioned in a region where the surface temperature of the film to be adhered is below the dew point. A method for manufacturing a laminated piezoelectric film according to claim 1.
  5. The temperature control roll is heated. A method for manufacturing a laminated piezoelectric film according to claim 1.
  6. The glass transition temperature of the adhesive, as measured in accordance with JIS K 6240:2001, is between -100°C and 0°C. A method for manufacturing a laminated piezoelectric film according to claim 1.
  7. In the coating step, an amount of the adhesive is applied such that the amount of solvent with a boiling point of 100°C or less is 1.0 g/(cm·min) or more and 10.0 g/(cm·min) or less. A method for manufacturing a laminated piezoelectric film according to claim 1.
  8. The piezoelectric film is mainly composed of a fluororesin. A method for manufacturing a laminated piezoelectric film according to claim 1.
  9. The aforementioned adhesive film is a release film, In the step of applying the adhesive, the adhesive is applied to the release surface of the release film. A method for manufacturing a laminated piezoelectric film according to claim 1.
  10. After peeling off the release film and transferring the adhesive layer to the piezoelectric film, an electrode film having a conductive layer with a surface resistivity of 1.0 × 10⁴ Ω/sq. or less is adhered to the piezoelectric film. A method for manufacturing a laminated piezoelectric film according to claim 9.

Description

This invention relates to a method for manufacturing a laminated piezoelectric film. Transparent and flexible piezoelectric films, such as polylactic acid films and fluororesin films, are used as laminated piezoelectric films by laminating them with thin-film electrodes and protective films. Furthermore, by using transparent conductive films containing fine conductive fibers such as indium tin composite oxide (ITO), metal nanowires, or mesh as thin-film electrodes, they are also used as transparent laminated piezoelectric films. ITO, after being laminated by methods such as sputtering, needs to be treated at high temperatures to enhance its crystallinity in order to improve its transparency and conductivity. However, piezoelectric films can become discolored or lose piezoelectric properties when exposed to high temperatures. A known method for producing transparent laminated piezoelectric films without exposing piezoelectric films to high temperatures involves applying an adhesive, such as an optically transparent adhesive (OCA), to a transparent conductive film made by sputtering ITO onto a polymer film such as polyethylene terephthalate (PET) and heat-treating it, or to a transparent conductive film containing fine conductive fibers, and then adhering it to a piezoelectric film. This method is used not only for laminating films with transparent conductive films as electrodes, but also for laminating protective films and metal thin films used as electrodes. In this method, an adhesive, in which the adhesive component is dissolved in a carrier solvent, is applied to the surface of the polymer film or metal thin film to be adhered to the piezoelectric film. The solvent is then removed to form an adhesive layer on the surface of the polymer film or metal thin film. A laminated piezoelectric film is then formed by adhering the piezoelectric film to this adhesive layer. Furthermore, by using a release film as the polymer film, a laminated film of piezoelectric film, adhesive layer, and release film can also be produced using the same method. In the above method, the application of adhesive to polymer films and metal thin films, the removal of solvents, and the lamination of piezoelectric films are generally performed continuously using a roll-to-roll method. Incidentally, it is known that when coating a film with a paint containing a solvent such as an adhesive and then removing the solvent, a brushing phenomenon occurs. The brushing phenomenon occurs when the solvent rapidly evaporates, causing latent heat of vaporization to be removed from the coated surface, resulting in condensation of moisture from the atmosphere onto the coating film. This can lead to uneven thickness of the dried coating film or the formation of irregularities on the coating film surface. Methods to avoid the brushing phenomenon include optimizing the coater temperature and the drying time after application (Patent Document 1), optimizing the type and composition of the solvent (Patent Document 2), and controlling the dew point of the atmosphere (Patent Document 3). Japanese Patent Publication No. 2002-326049Japanese Patent Publication No. 2018-030118Japanese Patent Publication No. 2018-030120 Figure 1 is a schematic diagram showing the manufacturing process of a laminated piezoelectric film according to one embodiment of the present invention.Figure 2 is a magnified view of a portion of region X shown in Figure 1, and is a schematic diagram illustrating how adhesive is applied to the 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 film to be transported.Figure 4 is a magnified view of region Z shown in Figure 1, and is a schematic diagram illustrating how the adhesive layer adheres the film to be adhered and the piezoelectric film. [Method for manufacturing laminated piezoelectric film] One embodiment of the present invention relates to a method for manufacturing a laminated piezoelectric film, wherein a film to be adhered to, coated with an adhesive, is conveyed by a guide roll. Figure 1 is a schematic diagram showing the manufacturing process of a laminated piezoelectric film in this embodiment. The laminated piezoelectric film is manufactured by applying an adhesive to a film to be adhered to, drying the applied adhesive to form an adhesive layer, and then adhering the piezoelectric film to the film using the formed adhesive layer. As shown in Figure 1, in this embodiment, the laminated piezoelectric film can be manufactured using a roll-to-roll method. The type of film to be adhered is not particularly limited, but can include electrode films such as metal foils and transparent conductive films, release films, antistatic films, protective films, and films having optical adjustment layers. The electrode film is not particularly limited as long as the surface resistance of the conductive layer is 1.0 × 10⁴ Ω/sq. or less, b