JP-2022541609-A5 -

Dates

Publication Date

20230509

Application Date

20200720

Description

In the method according to the present invention, the positive c-plate retarder layer is formed from a composition comprising a polymerizable liquid crystal and one or more photo-aligning materials. The resulting retarder layer has the property that, upon exposure to alignment light, its surface exhibits planar or inclined alignment capabilities for alignable materials such as liquid crystal materials. In the context of this application, PAPC material means a composition comprising a homeotropically oriented polymerizable liquid crystal and a photo-aligning material. Therefore, a PAPC layer is a layer formed from PAPC material. In structure 2 of Figure 2, a layer 13 of a slave material, such as a crosslinkable liquid crystal material, is directly coated onto the surface of the PAPC layer. The slave material is oriented by the photo -oriented surface of the PAPC layer 12. Preferably, the slave material includes an LCP material. The LCP material may further include additives such as a dichroic dye and/or a chiral additive. Therefore, the layer 13 may be birefringent, act as a polarizer, be twisted, or be cholesteric. The LCP molecules in the layer 13 may be planar or inclined. Preferably, layer 13 is birefringent and contains planar oriented liquid crystal, where planar means parallel to the surface of the layer. In this case, structure 2 in Figure 2 combines a positive c-plate retarder and a planar retarder (a-plate). It is noted that this structure can be made with just two layers. Preferably, layer 13 acts as a quarter-wave or half-wave retarder. It is particularly preferable that layer 13 is an achromatic retarder. Next, the film was visually observed again between the cross polarizers. Here, when viewed perpendicular to the substrate, it was found that a birefringent film oriented uniaxially was formed with a clear alignment of optical axes. Conoscopy observation with a polarizing microscope using a tilt compensator revealed that the optical axes were planar and parallel to the polarization direction of the UVB light irradiated onto the PAPC1 layer. It was concluded that an alignment was formed on the surface of the PAPC1 layer, and the LCP1 liquid crystal was aligned along the induced alignment direction. Next, the film was visually observed again between the cross polarizers. Here, when viewed perpendicular to the substrate, it was found that a birefringent film oriented uniaxially was formed with a clear alignment of optical axes. Conoscopy observation with a polarizing microscope using a tilt compensator revealed that the optical axes were planar and parallel to the polarization direction of the UVB light irradiated onto the PAPC 2 layer. It was concluded that an alignment was formed on the surface of the PAPC 2 layer, and the LCP1 liquid crystal was aligned along the induced alignment direction. A layer was formed on three exposed PAPC layers using a KBar coating (bar size 1) from a cholesteric LCP solution, S-cLCP. The wet film was annealed and dried in an oven at 99°C for 60 seconds, and then crosslinked at room temperature under nitrogen by irradiation with 1500 mJ/ cm² of high-pressure mercury lamp light. The film was found to act as a well-aligned cholesteric film and exhibited blue coloration in reflection. When the film was viewed under oblique incidence, it showed redshift. The present invention and its different embodiments can be summarized by the following clauses. 1. A method for manufacturing an optical element (1, 2) comprising a photo -oriented positive c-plate retarder layer , The steps include providing a PAPC material composition comprising a homeotropically oriented polymerizable liquid crystal and a photo-aligning material, A step of forming a layer (12) of PAPC material on a support (11), wherein liquid crystal molecules are arranged in a homeotropic manner. A step of initiating polymerization of polymerizable liquid crystal within the PAPC layer, A step of exposing a PAPC layer (12) to orientation light to generate orientation on the upper surface of the layer for the slave material, wherein the generated orientation direction is planar or inclined with respect to the surface of the PAPC layer in at least one region of the upper surface. A method that includes this. 2. The method according to claim 1, wherein polymerization of the polymerizable liquid crystal is initiated before the PAPC layer (12) is exposed to alignment light. 3. The method according to claim 1, wherein polymerization of the polymerizable liquid crystal is initiated after the PAPC layer (12) is exposed to alignment light. 4. The method according to Clause 1, wherein the polymerization and orientation of the polymerizable liquid crystal is initiated in a single step of exposing the PAPC layer (12) to alignment light. 5. The method according to any one of the claims 1 to 4, wherein the photo-aligning material in the PAPC layer has a density gradient such that the concentration of the photo-aligning material is