Retardation plate and method for producing retardation plate
AssigneeZeon Corporation
InventorsTaku HATANO, Kazuya GOUDA
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Abstract
A phase difference plate including: a first layer which is formed from a resin having a positive intrinsic birefringence value, and has birefringence; and a second layer which is formed from a resin having a negative intrinsic birefringence value, and has birefringence, wherein a retardation Re(450) at a wavelength of 450 nm of the phase difference plate, a retardation Re(550) at a wavelength of 550 nm of the phase difference plate, and a thickness d of the phase difference plate satisfy formula (I) Re(450)/Re(550)<0.92 and formula (II) Re(550)/d>0.0035; and production method therefor.
Claims10
A phase difference plate comprising:
- a first layer which is formed from a resin having a positive intrinsic birefringence value, and has birefringence;
- and
- a second layer which is formed from a resin having a negative intrinsic birefringence value, and has birefringence, wherein
- a retardation Re(450) at a wavelength of 450 nm of the phase difference plate, a retardation Re(550) at a wavelength of 550 nm of the phase difference plate, and a thickness d of the phase difference plate satisfy formula (I) and formula (II),
- Re(450)/Re(550)<0.92 (I), and
- Re(550)/d>0.0035 (II).
A method for producing a phase difference plate, the method comprising:
- a first step of co-extruding a resin having a positive intrinsic birefringence value and a resin having a negative intrinsic birefringence value to obtain a pre-stretch layered body which includes a first layer formed from the resin having a positive intrinsic birefringence value and a second layer formed from the resin having a negative intrinsic birefringence value;
- a second step of stretching the pre-stretch layered body after the first step to obtain a stretched body, wherein a retardation Re(450) at a wavelength of 450 nm of the stretched body and a retardation Re(550) at a wavelength of 550 nm of the stretched body satisfy formula (I);
- and
- a third step of promoting crystallization of at least one of the resin having a positive intrinsic birefringence value and the resin having a negative intrinsic birefringence value of the stretched body after the second step to obtain a phase difference plate in which the retardation Re(550) at a wavelength of 550 nm and a thickness d satisfy formula (II),
- Re(450)/Re(550)<0.92 (I), and
- Re(550)/d>0.0035 (II).
Dependencies are inferred from the claim text.