Pressure-sensitive adhesive optical film and image display
A pressure-sensitive adhesive optical film of the present invention comprises: an optical film comprising a transparent base film and a discotic liquid crystal layer on one side of the transparent base film; and a pressure-sensitive adhesive layer that is provided on the discotic liquid crystal layer, wherein the pressure-sensitive adhesive layer is made from a pressure-sensitive adhesive containing an acrylic polymer comprising an alkyl(meth)acrylate (a1) and a ring structure-containing (meth)acrylate (a2) as monomer units and having a weight average molecular weight of 1,000,000 to 3,000,000, and a crosslinking agent. The pressure-sensitive adhesive optical film has durability and can be prevented from causing display unevenness in a peripheral portion of a display screen.
1. A pressure-sensitive adhesive optical film, comprising:
an optical film comprising a transparent base film and a discotic liquid crystal layer on one side of the transparent base film; and a pressure-sensitive adhesive layer that is provided on the discotic liquid crystal layer, wherein the pressure-sensitive adhesive layer is made from a pressure-sensitive adhesive containing an acrylic polymer comprising 30 to 90% by weight of an alkyl(meth)acrylate (a1) and 10 to 70% by weight of a ring structure-containing (meth)acrylate (a2) as monomer units and a crosslinking agent, wherein the ring structure-containing (meth)acrylate (a2) is an aromatic ring structure-containing (meth)acrylate where the aromatic ring structure is linked by an ether linkage which produces higher polarizability,
a weight average molecular weight of the acrylic polymer is within a range of above 2,000,000 to 3,000,000, and the percentage of components with a molecular weight of 100,000 or less in the acrylic polymer is 15% or less by area as measured by gel permeation chromatography.
2. The pressure-sensitive adhesive optical film according to claim 1 , wherein the acrylic polymer further comprises 10% or less by weight of a monomer unit (a3) besides the components (a1) and (a2).
3. The pressure-sensitive adhesive optical film according to claim 2 , wherein the monomer unit (a3) is selected from the group consisting of hydroxyl group-containing monomers, carboxyl group-containing monomers, acid anhydride group-containing monomers, sulfonic acid group-containing monomers and phosphate group-containing monomers.
4. The pressure-sensitive adhesive optical film according to claim 1 , wherein the pressure-sensitive adhesive contains a silane coupling agent.
5. The pressure-sensitive adhesive optical film according to claim 1 , wherein the pressure-sensitive adhesive layer is provided on the discotic liquid crystal layer via an undercoat layer.
6. The pressure-sensitive adhesive optical film according to claim 5 , wherein the undercoat layer is made of a polyethyleneimine-based material.
7. The pressure-sensitive adhesive optical film according to claim 1 , wherein the optical film further comprises a polarizer that is laminated on another side of the transparent base film where the discotic liquid crystal layer is not provided.
8. An image display, comprising the pressure-sensitive adhesive optical film according to claim 1 .
9. The pressure-sensitive adhesive optical film according to claim 1 , wherein the ring structure-containing (meth)acrylate (a2) is selected from the group consisting of phenoxyethyl(meth)acrylate, phenoxy-2-hydroxypropyl(meth)acrylate, phenol ethylene oxide-modified (meth)acrylate, 2-naphthoxyethyl(meth)acrylate, 2-(4-methoxy-1-naphthoxy)ethyl (meth)acrylate, phenoxypropyl(meth)acrylate and phenoxyethylene glycol(meth)acrylate.
10. The pressure-sensitive adhesive optical film according to claim 1 , wherein the crosslinking agent is selected from the group consisting of an isocyanate type crosslinking agent, epoxy type crosslinking agent, peroxide type crosslinking agent, metal chelate type crosslinking agent and oxazoline type crosslinking agent.
11. The pressure-sensitive adhesive optical film according to claim 1 , wherein the aromatic ring structure-containing (meth)acrylate is phenoxyethyl(meth)acrylate.