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JP-7855352-B2 - Laminates, optical devices, and display devices

JP7855352B2JP 7855352 B2JP7855352 B2JP 7855352B2JP-7855352-B2

Inventors

  • 柴田 直也
  • 桑山 靖和
  • 小糸 直希
  • 加藤 由実
  • 三戸部 史岳
  • 山田 直良

Assignees

  • 富士フイルム株式会社

Dates

Publication Date
20260508
Application Date
20201117
Priority Date
20191202

Claims (12)

  1. A laminate comprising at least a resin substrate, an orientation layer, and a light-absorbing anisotropic layer, The peak temperature of tanδ, determined by the following measurement method for the aforementioned resin substrate, is 170°C or lower. The orientation layer is a layer formed using a composition containing a polymer having photo-orienting groups and crosslinking groups, wherein the polymer has repeating units represented by the following formula (A1), A laminate in which the light-absorbing anisotropic layer contains a liquid crystalline compound and a dichroic substance, and the degree of orientation of the dichroic substance is 0.95 or higher. Measurement method: Using a dynamic viscoelasticity measuring device, the resin substrate, which has been pre-conditioned for at least two hours at a temperature of 25°C and a humidity of 60% Rh, is used to measure E'' (loss modulus) and E' (storage modulus) under the following conditions, and the value obtained from these measurements is used to determine tanδ (= E''/E'). Sample: 5 mm, 50 mm in length (20 mm gap) Measurement conditions: Tensile mode; Measurement temperature: -150°C to 220°C Temperature increase conditions: 5°C/min Frequency: 1 Hz In the above formula (A1), R3 represents a hydrogen atom or a methyl group, L1 represents a divalent linking group containing -C(O)NH- , a represents an integer from 0 to 5, and R1 represents a hydrogen atom or a monovalent organic group .
  2. The laminate according to claim 1 , wherein the peak temperature of the tanδ of the resin substrate is 130°C or less.
  3. The laminate according to claim 1 or 2 , wherein the storage modulus of the resin substrate at the peak temperature of tanδ is 100 kPa or less.
  4. The laminate according to any one of claims 1 to 3 , wherein the resin substrate, adhesive layer, light-absorbing anisotropic layer, and orientation layer are arranged in this order.
  5. The laminate according to claim 4 , wherein the adhesive layer is an ultraviolet-curable adhesive layer.
  6. The laminate according to claim 5 , wherein the adhesive layer is an adhesive layer containing at least a (meth)acrylate compound.
  7. The laminate according to claim 1 , wherein the light-absorbing anisotropic layer is formed from a composition having a polymeric liquid crystalline compound.
  8. The laminate according to claim 1, wherein the molar content of radical polymerizable groups relative to the solid content weight of the composition forming the light-absorbing anisotropic layer is 0.6 mmol/g or more.
  9. A laminate according to claim 1, having a curved surface.
  10. An optical device having a curved surface, An optical device in which the laminate according to claim 9 is arranged to conform to the curved surface.
  11. A display device having multiple members having curved surfaces, A display device in which the laminate according to claim 9 is arranged so as to be even more visible on the curved side of the curved surface of the member that is on the most visible side among the members having a curved surface.
  12. An optical system having multiple members having curved surfaces, The laminate according to claim 9 is arranged such that, among the plurality of members having a curved surface, the member that is on the most visible side is further aligned with the visible side of the curved surface. An optical system comprising a plurality of curved members, including a reflective linear polarizer or a reflective circular polarizer, a quarter-wave plate, and a half-mirror.

Description

This invention relates to a laminate, an optical device, and a display device. Polarizers are used in various optical devices for purposes such as anti-reflection and stray light suppression, but for each component used, there is a need for greater freedom in shape, such as curved surfaces, to improve aesthetics and ease of design. Conventionally, iodine polarizers have often been used as polarizers. Iodine polarizers are manufactured by dissolving iodine, adsorbing it onto a polymer material film such as polyvinyl alcohol (PVA), and stretching it at a high magnification in one direction, making it difficult to achieve sufficient thinness. Furthermore, as described in Patent Document 1, the stretched PVA is prone to shape changes over time due to heat, making it difficult to use in curved shapes. In recent years, polarizing elements have been investigated that involve coating a liquid crystalline compound or a dichroic azo dye onto a substrate such as a transparent film, and then aligning the dichroic azo dye using intermolecular interactions. For example, Patent Document 1 describes a polarizer for use in a polarizing plate having a curved portion, having a first surface and a second surface, and having a thickness of 15 μm or less ([Claim 1]). Furthermore, as such a polarizer, a polarizer containing a cured liquid crystalline compound and a dichroic dye, and including a polarizing layer in which the dichroic dye is dispersed and oriented, is also described ([Claim 4]). Japanese Patent Publication No. 2019-194685 Figure 1 is a schematic cross-sectional view showing an example of the laminate of the present invention.Figure 2 is a schematic cross-sectional view showing an example of the laminate of the present invention.Figure 3 is a cross-sectional side view of a head-mounted display, which is an example of a display device according to the present invention.Figure 4 is a cross-sectional side view of a head-mounted display, which is an example of a display device according to the present invention.Figure 5 is a schematic diagram showing the orientation of the laminate according to the present invention. The present invention will be described in detail below. The following description of the constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, a numerical range indicated by "～" means a range that includes the numbers written before and after "～" as the lower and upper limits, respectively. Furthermore, in this specification, parallel, orthogonal, horizontal, and vertical do not mean parallel, orthogonal, horizontal, and vertical in the strict sense, but rather mean a range of ±10° for parallel, ±10° for orthogonal, ±10° for horizontal, and ±10° for vertical, respectively. Furthermore, in this specification, each component may be represented by a single substance or by a combination of two or more substances. When two or more substances are used in combination for each component, the content of that component refers to the total content of the combined substances unless otherwise specified. Furthermore, in this specification, "(meth)acrylate" refers to "acrylate" or "methacrylate,""(meth)acrylic" refers to "acrylic" or "methacrylic," and "(meth)acryloyl" refers to "acryloyl" or "methacryloyl." [Laminate] The laminate of the present invention is a laminate having a resin substrate and a light-absorbing anisotropic layer, wherein the tanδ of the resin substrate is 170°C or less, the light-absorbing anisotropic layer contains a liquid crystalline compound and a dichroic substance, and the degree of orientation of the dichroic substance is 0.95 or more. The degree of orientation of the dichroic material in the light-absorbing anisotropic layer is more preferably 0.97 or higher. The higher the degree of orientation, the smaller the change in polarization degree when stretched simultaneously in multiple directions. In the present invention, as described above, the peak temperature of the tanδ of the resin substrate is 170°C or lower, and the dichroic substance in the light-absorbing anisotropic layer has a high degree of orientation of 0.95 or higher. Therefore, even when stretched in a direction different from the direction of the orientation axis, or in multiple directions simultaneously, a decrease in the degree of polarization can be suppressed. The details of this reason are still unclear, but the inventors speculate that it is due to the following reasons. First, it can be estimated that the optical laminate of the present invention has a tanδ peak temperature of 170°C or less, which allows it to be stretched in a temperature range that does not affect the orientation state of the liquid crystalline compound in the light-absorbing anisotropic layer, and that a curved shape can be imparted to it in that temperature range. Furthermore, the light-absorbing anisotropic layer of the optical laminate