Method of producing a patterned birefringent product
A method of producing a patterned birefringent product, containing at least steps (I) to (III) in this order: (I) providing a birefringent pattern builder having an optically anisotropic layer containing a polymer; (II) subjecting two or more regions of the birefringent pattern builder to exposure to light under exposure conditions different from each other; and (III) heating a laminated structure obtained after the step (II) at 50° C. or higher and 400° C. or lower.
1. A method of producing a patterned birefringent product, comprising at least steps (I) to (III) in this order:
(I) providing a birefringent pattern builder having an optically anisotropic layer containing a polymer having an unreacted reactive group, the optically anisotropic layer being obtained by coating with a solution containing a liquid crystalline compound having two or more types of reactive groups each of which having different polymerization condition, drying the thus-coated solution to thereby form a liquid crystal phase, and then applying heat or irradiating ionized radiation to the liquid crystal phase to thereby cause polymerization and fixation;
(II) subjecting two or more regions of the birefringent pattern builder to patterned light exposure under exposure conditions that differ from each other in at least one of exposure intensity, exposure quantity, exposure time period, and exposure peak wavelength; and
(III) heating a laminated structure obtained after the step (II) at 50° C. or higher and 400° C. or lower.
2. The method according to claim 1 , wherein the exposure of two or more regions is performed by using an exposure mask having patterns different from each other.
3. The method according to claim 1 , wherein the step (II) is carried out by single exposure by using an exposure mask having two or more regions showing transmission spectra different from each other.
4. The method according to claim 1 , wherein the in-plane retardation at 20° C. of the optically anisotropic layer is 10 nm or more.
5. The method according to claim 1 , wherein the liquid crystalline compound at least has a radically reactive group and a cationically reactive group.
6. The method according to claim 5 , wherein the radically reactive group is an acrylic group and/or a methacrylic group, and the cationically reactive group is a vinyl ether group, an oxetanyl group, and/or an epoxy group.
7. The method according to claim 1 , wherein the optically anisotropic layer is a stretched film.
8. The method according to claim 1 , wherein the step is carried out by conducting transfer of a transferring material which has the optically anisotropic layer, to a target transfer material.
9. A product, which is obtainable from the method according to claim 1 , wherein the change in retardation (phase difference) thereof after baking at 200° C. for 30 minutes is 10% or less.
10. A product used as mean of preventing forgery, which is obtainable from the method according to claim 1 .
11. A product used as an optical element, which is obtainable from the method according to claim 1 .