OPTICAL FILM, METHOD FOR PRODUCING THE SAME, POLARIZING PLATE AND IMAGE DISPLAY DEVICE

• US 20090202819A1
• Filed: 02/13/2009
• Published: 08/13/2009
• Est. Priority Date: 02/13/2008
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Watanabe, Jun, Fukuda, Kenichi, Inque, Katsumi, Asahi, Miho
• Granted Patent: US 8,389,049 B2
• Time in Patent Office: Days
• US Class Current: 428/336
• CPC Class Codes: G02B 1/111 using layers comprising organic materials
• CPC Class Codes: G02B 1/113 using inorganic layer materials only
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: Y10T 428/249961 With gradual property change within a component
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

An optical film, includes, a transparent support; and an optical functional layer as the outermost layer of the optical film, the optical functional layer being provided on or above the transparent support, wherein the optical functional layer has a thickness of 50 nm or more and not more than 250 nm the optical functional layer contains low refractive index fine particles having a refractive index of not more than 1.45, high refractive index fine particles having a refractive index of 1.55 or more) and a fluorine-containing compound; the low refractive index fine particles are arranged substantially in a line on a surface of the optical functional layer on the opposite side of the transparent support; and the high refractive index fine particles are unevenly distributed in a lower part of the optical functional layer on the side of the transparent support.

Claims

1. An optical film, comprising:

a transparent support; and

an optical functional layer as the outermost layer of the optical film, the optical functional layer being provided on or above the transparent support,

wherein the optical functional layer has a thickness of 50 nm or more and not more than 250 nm;

the optical functional layer contains low refractive index fine particles having a refractive index of not more than 1.45, high refractive index fine particles having a refractive index of 1.55 or more, and a fluorine-containing compound;

the low refractive index fine particles are arranged substantially in a line on a surface of the optical functional layer on the opposite side of the transparent support; and

the high refractive index fine particles are unevenly distributed in a lower part of the optical functional layer on the side of the transparent support.

2. The optical film according to claim 1,

wherein the optical functional layer contains the low refractive index fine particles in a range of from 5% by mass to 15% by mass with respect to the entire solid content of the optical functional layer.

3. The optical film according to claim 1,

wherein the optical functional layer contains the high refractive index fine particles in a range of from 30% by mass to 50% by mass with respect to the entire solid content of the optical functional layer.

4. The optical film according to claim 1,

wherein the low refractive index fine particles are silica fine particles or hollow silica fine particles.

5. The optical film according to claim 1,

wherein a ratio of [(P_Lu/P_Lt)×

100] is 200% or more,

in which P_Lt represents an average particle packing factor of the low refractive index fine particles in the whole layer of the optical functional layer; and

P_Lu represents an average particle packing factor of the low refractive index fine particles in the 30% thickness in an upper part of the optical functional layer on the opposite side of the transparent support.

6. The optical film according to claim 1,

wherein a ratio of [(P_Hd/P_Ht)×

100] is 120% or more,

in which P_Ht represents an average particle packing factor of the high refractive index fine particles in the whole layer of the optical functional layer; and

P_Hd represents an average particle packing factor of the high refractive index fine particles in the 50% thickness in a lower part of the optical functional layer on the side of the transparent support.

7. The optical film according to claim 1,

wherein the low refractive index fine particles are surface-modified with a fluorine atom-free silane coupling agent.

8. The optical film according to claim 1,

wherein the high refractive index fine particles are oxide fine particles of at least one element selected from the group consisting of aluminum, zirconium, titanium, zinc, germanium, indium, tin, antimony and cerium.

9. A polarizing plate, comprising:

the optical film according to claim 1 as a protective film for the polarizing plate.

10. An image display device, comprising:

the optical film according to claim 1.

14. The method according to claim 1,

wherein the low refractive index fine particles are surface-modified with a fluorine atom-free silane coupling agent.

11. A method for producing an optical film that includes a transparent support and an optical functional layer as the outermost layer of the optical film, the method comprising:

applying a curable composition directly or indirectly on the transparent support, the curable composition containing low refractive index fine particles having a refractive index of not more than 1.45, high refractive index fine particles having a refractive index of 1.55 or more, and a fluorine-containing compound; and

curing the curable composition to form an optical functional layer having a thickness of 50 nm or more and not more than 250 nm,

wherein in the optical functional layer, the low refractive index fine particles are arranged substantially in a line on a surface of the optical functional layer on the opposite side of the transparent support; and

the high refractive index fine particles are unevenly distributed in a lower pan of the optical functional layer on the side of the transparent support.

13. The method according to claim 11,

wherein the low refractive index fine particles are silica fine particles or hollow silica fine particles.

12. A method for producing an optical film that includes a transparent support and an optical functional layer as the outermost layer of the optical film) the method comprising:

applying curable compositions 1 and 2 directly or indirectly on the transparent support by using a coating device that includes at least one member selected from the group consisting of adjacent two slot dies and a slide-type coating head while supporting the transparent support by backup rollers and traveling the transparent support,

the curable composition 1 containing low refractive index fine particles having a refractive index of not more than 1.45 and a fluorine-containing compound,

the curable composition 2 containing high refractive index fine particles having a refractive index of 1.55 or more; and

curing the curable compositions 1 and 2 to form an optical functional layer having a thickness of 50 nm or more and not more than 250 nm,

wherein in the optical functional layer, the low refractive index fine particles are arranged substantially in a line on a surface of the optical functional layer on the opposite side of the transparent support; and

the high refractive index fine particles are unevenly distributed in a lower part of the optical functional layer on the side of the transparent support.

15. The method according to claim 12,

wherein the low refractive index fine particles are silica fine particles or hollow silica fine particles.

16. The method according to claim 12,

wherein the low refractive index fine particles are surface-modified with a fluorine atom-fee silane coupling agent.