Laminate film
A laminate film comprising a retardation layer exhibiting blocking characteristics against specific ultraviolet rays even in a state where the retardation layer does not include any ultraviolet absorber or light stabilizer. The laminate film which can be used alone or in combination with an appropriate sunscreen or a light stabilizer as needed to selectively block ultraviolet rays in a region requiring blocking, without affecting display performance, such as color senses and image quality, of a display device. The laminate film can also be formed with a lower thickness without requiring a separate ultraviolet blocking layer, and also has excellent durability, because the laminate film exhibits a certain ultraviolet blocking property even in the absence of an ultraviolet absorber or light stabilizer.
1. A laminate film comprising a base film; and a retardation layer formed on one side of the base film,
wherein the retardation layer has a quarter-wave phase delay characteristics, and comprises a polymerized unit of a normal wavelength dispersion polymerizable liquid crystal compound and a polymerized unit of a reverse wavelength dispersion polymerizable liquid crystal compound,
wherein the retardation layer comprises neither an ultraviolet absorber nor a light stabilizer, and
wherein the retardation layer has an ultraviolet absorptivity such that a transmittance of light having a wavelength of 385 nm through the retardation layer is 3% or less, a transmittance of light having a wavelength of 390 nm through the retardation layer is greater than 3% and less than 10%, and a transmittance of light having a wavelength of 395 nm through the retardation layer is greater than or equal to 10% and less than 25%; and
wherein the reverse wavelength dispersion polymerizable liquid crystal compound is represented by Formula 1 below:
wherein in Formula 1, R 1 is a substituent of Formula 2 or 3 below, and R 2 to R 6 are each independently hydrogen, an alkyl group, an alkoxy group, a cyano group, a substituent of Formula 4 below or a substituent of Formula 5 below, wherein at least two of R 2 to R 6 are substituents of Formula 4 below or substituents of Formula 5 below,
-A 1 -L 1 -Cyc-A 2 -L 2 -P [Formula 2]
wherein, in Formula 2, A 1 and A 2 are each independently an oxygen atom or a single bond, L 1 and L 2 are each independently —C(═O)—O—, —O—C(═O)— or an alkylene group, Cyc is an arylene group or a cycloalkylene group, and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group,
wherein, in Formula 3, L 3 and L 4 are each an alkylene group, n is a number in a range of 1 to 4, and P is an acryloyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group or a hydrogen atom,
-A 3 -L 5 -Cyc-A 4 -L 6 -P [Formula 4]
wherein in Formula 4, A 3 and A 4 are an oxygen atom, an alkylene group or a single bond, L 5 and L 6 are each independently —C(═O)—O—, —O—C(═O)— or an alkylene group, Cyc is an arylene group, and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group,
-A 5 -L 7 -Cy 1 -A 6 -L 8 -Cy 2 -A 7 -L 9 -P [Formula 5]
wherein in Formula 5, A 5 , A 6 and A 7 are each independently an oxygen atom or a single bond, L 7 , L 8 and L 9 are each independently —C(═O)—O—, —O—C(═O)— or an alkylene group, Cy 1 is a cycloalkylene group, Cy 2 is an arylene group, and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group,
wherein the reverse wavelength dispersion polymerizable liquid crystal compound includes a reverse wavelength dispersion polymerizable liquid crystal compound having tri-functionality or more; and
wherein the normal wavelength dispersion polymerizable liquid crystal compound is represented by Formula 6 below:
wherein in Formula 6, A is a single bond, —C(═O)O— or —OC(═O)— and R 1 to R 10 are each independently hydrogen, halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group or a substituent of Formual 7 below, or two neighboring substituents selected from R 1 to R 5 , or two neighboring substituents selected from R 6 to R 10 , are bonded to each other to constitute a benzene ring substituted with an -L′-A′-P′ group, wherein in the -L′-A′-P′ group, L′ is —C(═O)O—, —OC(═O)— or —OC(═O)O—, A′ is an alkylene group and P′ is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group,
wherein in Formula 7, B is a single bond, —C(═O)O— or —OC(═O)— and R 11 to R 15 are each independently hydrogen, halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group or an -L-A-P group, or two neighboring substituents of R 11 to R 15 are bonded to each other to constitute a benzene ring substituted with an -L-A-P group, wherein in the -L-A-P group, L is —C(═O)O—, —OC(═O)— or —OC(═O)O—, A is an alkylene group and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group.
2. The laminate film according to claim 1 , wherein the retardation layer has an absolute value of a retardation change ratio according to Equation A below of 17% or less:
Retardation change ratio=100×( Ra−Ri )/ Ri, [Equation A]
wherein in Equation A, Ri is an initial in-plane retardation of the retardation layer for a wavelength of 550 nm, and Ra is an in-plane retardation of the retardation layer for a wavelength of 550 nm after an endurance condition, and
wherein the endurance condition includes the retardation layer standing at a temperature of 85° C. for 50 hours or more.
3. The laminate film according to claim 1 , wherein a transmittance of light having a wavelength of 400 nm through the retardation layer is 40% or less.
4. The laminate film according to claim 1 , further comprising a vertically oriented liquid crystal layer having a polymerized unit of a vertically oriented polymerizable liquid crystal compound between the base film and the retardation layer, or on a side of the base film opposite to the retardation layer.
5. The laminate film according to claim 4 , further comprising a horizontal alignment film and a vertical alignment film, wherein the base film, the horizontal alignment film, the retardation layer, the vertical alignment film and the vertically oriented liquid crystal layer are disposed in this order.
6. The laminate film according to claim 4 , further comprising a horizontal alignment film and a vertical alignment film, wherein the base film, the vertical alignment film, the vertically oriented liquid crystal layer, the horizontal alignment film and the retardation layer are disposed in this order.
7. The laminate film according to claim 4 , wherein the vertically oriented liquid crystal layer satisfies Equation 9 below:
Rth (450)/ Rth (550)< Rth (650)/ Rth (550), [Equation 9]
wherein in Equation 9, Rth (450) is a thickness direction retardation of the vertically oriented liquid crystal layer for light having a wavelength of 450 nm, Rth (550) is a thickness direction retardation of the vertically oriented liquid crystal layer for light having a wavelength of 550 nm, and Rth (650) is a thickness direction retardation of the vertically oriented liquid crystal layer for light having a wavelength of 650 nm.
8. The laminate film according to claim 1 , wherein the retardation layer comprises 30 wt % or more of the polymerized unit of the normal dispersion polymerizable liquid crystal compound and the polymerized unit of the reverse dispersion polymerizable liquid crystal compound having tri-functionality or more based on the total amount of the polymerized unit of the normal dispersion polymerizable liquid crystal compound and the polymerized unit of the reverse dispersion polymerizable liquid crystal compound.
9. The laminate film according to claim 1 , wherein the base film is formed so as to be peeled from the retardation layer.
10. A display device comprising the laminate film of claim 1 .