JP-2026075880-A - Titanium oxide film and method for producing the same

Abstract

[Problem] To provide a titanium oxide film with excellent anti-reflective properties and manufacturing efficiency, and a method for manufacturing the same. [Solution] The titanium oxide film 1 contains a crystal in which a group of Ti₂O₃ diffraction spots appear in the electron diffraction pattern observed with a transmission electron microscope, and the refractive index when light with a wavelength of 550 nm is incident on it is greater than 2.50 and less than or equal to 2.80. [Selection Diagram] Figure 1

Inventors

• 林 雄二郎
• 中島 一裕
• 荻田 拓哉
• 杉本 皓輔
• 長命 翔太

Assignees

• 日東電工株式会社

Dates

Publication Date

20260511

Application Date

20241023

Claims (5)

1. The crystal contains a group of Ti₂O₃ diffraction spots in the electron diffraction pattern observed with a transmission electron microscope. A titanium oxide film whose refractive index, when incident on light with a wavelength of 550 nm, is greater than 2.50 and less than or equal to 2.80.
2. The titanium oxide film according to claim 1, wherein the refractive index exceeds 2.68.
3. The method for producing a titanium oxide film according to claim 1, A method for producing a titanium oxide film, comprising the step of forming the titanium oxide film on one side of the thickness direction of a substrate using high-power impulse magnetron sputtering (HiPIMS) at a film formation temperature of 70°C or higher.
4. The method for producing a titanium oxide film according to claim 3, wherein the above-mentioned step is carried out with the film formation temperature set to 100°C or higher.
5. The method for producing a titanium oxide film according to claim 3 or 4, wherein the above step is carried out by a roll-to-roll method.

Description

This invention relates to a titanium oxide film and a method for producing the same. In image display devices such as liquid crystal displays and organic EL displays, an anti-reflective film is placed on the outermost surface of the display screen to prevent reflection of ambient light. Such an anti-reflective film comprises a transparent substrate film and an anti-reflective layer including a high refractive index layer and a low refractive index layer. As a high refractive index layer used in such anti-reflective films, a rutile-type titanium oxide ( TiO₂ ) film has been proposed (see, for example, Patent Document 1). Japanese Patent Publication No. 2014-016459 Figure 1 shows one embodiment of a laminate comprising the titanium oxide film of the present invention.Figures 2A and 2B show one embodiment of the method for manufacturing a titanium oxide film according to the present invention. Figure 2A shows the first step of preparing a substrate, and Figure 2B shows the second step of forming a titanium oxide film on one side of the substrate in the thickness direction. 1. Titanium Oxide Film An embodiment of the titanium oxide film of the present invention will be described. As shown in Figure 1, the titanium oxide film 1 is, for example, one of the lamination elements of the laminate X described later. The titanium oxide film 1 is the uppermost layer of the laminate X. Specifically, the titanium oxide film 1 is positioned on one side in the thickness direction of the protective layer 23, which will be described later. In other words, the titanium oxide film 1 is in contact with the protective layer 23. The titanium oxide film 1 has a film shape (including a sheet shape) with a predetermined thickness. Furthermore, the titanium oxide film 1 extends in a plane direction perpendicular to the thickness direction, and one surface in the thickness direction and the other surface in the thickness direction of the titanium oxide film 1 are flat. The titanium oxide film 1 is a crystalline layer. The titanium oxide film 1 may also contain amorphous regions. Preferably, the titanium oxide film 1 is a layer containing only crystalline regions and no amorphous regions. The amorphous regions can be identified, for example, by observing the plane direction of the titanium oxide film 1 with a transmission electron microscope. The titanium oxide film 1 contains titanium (Ti) oxide. Specifically, the titanium oxide film 1 contains crystals in which a group of Ti₂O₃ diffraction spots appear in the electron diffraction pattern observed with a transmission electron microscope. In addition to crystals in which a group of Ti₂O₃ diffraction spots appear, the titanium oxide film 1 may also contain crystals in which other groups of diffraction spots appear. Specifically, the titanium oxide film 1 may contain crystals in which rutile-type TiO₂ , anatase-type TiO₂ , brookite-type TiO₂ , and TiO diffraction spots appear. Preferably, in the titanium oxide film 1, only the group of Ti₂O₃ diffraction spots appears in the electron diffraction pattern observed with a transmission electron microscope, and no other groups of diffraction spots appear . The crystal structure contained in the titanium oxide film 1 is identified in detail by the analysis of the electron diffraction pattern, as described later. The titanium oxide film 1 of the present invention contains crystals in which a group of Ti₂O₃ diffraction spots appear in the electron diffraction pattern observed with a transmission electron microscope. Therefore, the titanium oxide film 1 can be manufactured without annealing at a high temperature of 600°C or higher for a long period of time, as is done when depositing rutile-type TiO₂ . Consequently, the manufacturing efficiency of the titanium oxide film 1 is excellent. In the titanium oxide film 1 , the grain size of Ti₂O₃ is, for example, 5 nm or more, preferably 6 nm or more, more preferably 8 nm or more, and even more preferably 10 nm or more, and also, for example, 30 nm or less, preferably 28 nm or less, more preferably 26 nm or less, and even more preferably 25 nm or less. The grain size of Ti₂O₃ in the titanium oxide film 1 can be determined, for example, by observing the crystal grains in the planar direction of the titanium oxide film 1 with a transmission electron microscope. In the titanium oxide film 1, if the crystal grain size of Ti₂O₃ is within the upper and lower limits described above, the refractive index when light with a wavelength of 550 nm is incident on the titanium oxide film 1 will be greater than 2.50 and less than or equal to 2.80. In other words, when the titanium oxide film 1 is used as a high refractive index layer in an anti-reflective film, the reflection of ambient light is suppressed, and the anti-reflective film exhibits excellent anti-reflective performance. The refractive index of the titanium oxide film 1 when light with a wavelength of 550 nm is incident on it is greater than 2.50, preferably