Polarizer having non-polarizing part
Provided is a polarizer having a non-polarization portion with reduced shape unevenness. The polarizer of the present invention is a polarizer having a non-polarization portion, in which the non-polarization portion has a shape matching degree of 0.05 or less. In such polarizer, the number of portions where the shape of the non-polarization portion is distorted is small. Accordingly, when the non-polarization portion of the polarizer is used as, for example, a portion corresponding to a camera portion of an image display apparatus, alignment processability is improved and hence the alignment of the camera can be satisfactorily performed.
1. A polarizer, comprising a polarization portion and a non-polarization portion, wherein the non-polarization portion has a shape matching degree of 0.05 or less and 0.025 or more, where the shape matching degree is an indicator representing a degree of unevenness of a shape of the formed non-polarization portion in its radial direction with respect to an outer periphery of a designed non-polarization portion,
the non-polarization portion has a content of an alkali metal and/or an alkaline earth metal of 3.6 wt % or less, and
the polarizer comprises boric acid, a content of the boric acid in the polarization portion is 10 wt % to 30 wt %, the non-polarization portion having a reduced content of boric acid of 5 wt % to 12 wt %.
2. The polarizer according to claim 1 , wherein the non-polarization portion has a dichromatic substance content of 1.0 wt % or less.
3. A polarizing plate, comprising the polarizer of claim 2 , and a protective film.
4. A polarizing plate, comprising the polarizer of claim 1 , and a protective film.
5. An image display apparatus, comprising the polarizing plate of claim 4 , and a liquid display apparatus or an organic EL device.
6. The polarizer according to claim 1 , wherein the non-polarizing portion is produced by a method comprising the steps of:
(i) forming a laminate comprising a surface protective film laminated on to a surface of the polarizer through a pressure-sensitive adhesive layer, the surface protective film having at least one through-hole exposing a portion of the polarizer;
(ii) bringing a basic solution into contact with the exposed portion to form the non-polarization portion;
(iii) bringing a treatment liquid into contact with the non-polarization portion; and
(iv) a step of removing the basic solution and treatment liquid from the non-polarization portion.
7. The polarizer according to claim 6 , wherein the treatment liquid is selected from the group consisting of solvent water, ethanol, methanol, ethers, benzene, chloroform, and mixtures thereof.
8. The polarizer according to claim 6 , wherein the treatment liquid is an acidic compound selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, hydrogen fluoride, boric acid, formic acid, oxalic acid, citric acid, acetic acid, and benzoic acid.
9. The polarizer according to claim 6 , wherein the removing step including wiping, suction removal, natural drying, heat drying, blow drying, or drying under reduced pressure.
10. The polarizer according to claim 6 , wherein the thickness of the pressure-sensitive adhesive layer is 10 μm or less.
11. The polarizer according to claim 6 , wherein the basic solution is selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, sodium carbonate, sodium acetate, and ammonia water.