Optical element and method for manufacturing the same

Abstract

The present invention provides an optical element capable of improving the adhesive property between a refractive index anisotropic layer and an alignment property providing layer for. providing alignment property to the refractive index anisotropic layer and further improving the endurance of each of the layers. An optical element 10 has an alignment property providing layer 12 laminated on a transparent base material 11 and a refractive index anisotropic layer 13 laminated on the layer 12 . The layer 12 is an alignment layer having alignment limiting force for providing alignment property to the layer 13 , and is made of an alignment layer composition capable of expressing the alignment limiting force. The layer 13 is a liquid crystal layer formed by curing (polymerizing) a liquid crystal composition comprising a polymerizable liquid crystal material. A monomer or oligomer having one or more functional groups, together with a polymer, is incorporated into the alignment layer composition. The monomer or oligomer in the layer 12 is crosslinked with molecules in the layer 13 , which is adjacent to the layer 12 , near the interface between the layers 12 and 13.

1 . A method for manufacturing an optical element, comprising:
 a step of forming an alignment property providing layer as an alignment layer on a transparent base material, in which an alignment layer composition comprising a polymer and a monomer or an oligomer having one or more functional groups is applied onto the transparent base material to express an alignment limiting force on a surface thereof;   a step of applying a liquid crystal composition comprising a polymerizable liquid crystal material onto the alignment property providing layer formed on the transparent base material, and   a step of forming a refractive index anisotropic layer, in which the liquid crystal composition applied onto the alignment property providing layer on the transparent base material is cured to provide an alignment property to the alignment property providing layer by the alignment limiting force of the alignment property providing layer;   wherein in the step of forming the refractive index anisotropic layer, the alignment property providing layer together with the liquid crystal composition is cured to crosslink the monomer or the oligomer in the alignment property providing layer and the polymerizable liquid crystal material in the refractive index anisotropic layer with each other near an interface between the alignment property providing layer and the refractive index anisotropic layer.   
     
     
         2 . The method for manufacturing the optical element according to  claim 1 , wherein the alignment property providing layer formed on the transparent base material is made of an alignment layer composition capable of expressing the alignment limiting force by a photo alignment method. 
     
     
         3 . The method for manufacturing the optical element according to  claim 2 , wherein the polymer comprised in the alignment layer composition for forming the alignment property providing layer is the polymer having at least one of a cinnamate and a coumalin. 
     
     
         4 . The method for manufacturing the optical element according to  claim 1 , wherein themonomer or the oligomer comprised in the alignment layer composition for forming the alignment property providing layer is the polymerizable liquid crystal material. 
     
     
         5 . The method for manufacturing the optical element according to  claim 4 , wherein the polymerizable liquid crystal material in the alignment property providing layer and the polymerizable liquid crystal material in the refractive index anisotropic layer are of a same kind. 
     
     
         6 . The method for manufacturing the optical element according to  claim 1 , wherein a weight of the monomer or the oligomer comprised in the alignment layer composition for forming the alignment property providing layer is from 0.01 to 3 times that of the polymer. 
     
     
         7 . The method for manufacturing the optical element according to  claim 1 , wherein a weight of the monomer or the oligomer comprised in the alignment layer composition for forming the alignment property providing layer is from 0.05 to 1.5 times that of the polymer.