Optical film, anti-reflection film, polarizing plate and image display device

Abstract

An optical film, which comprises: a transparent support; and an optical layer on or above the transparent support, wherein the optical layer contains a thickening agent which shows a viscosity of 10 mPa·sec or more when added to 2-butanone in a content of 3% by mass, and the optical layer has a thickness of 5 μm or more.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view schematically showing a preferred exemplary embodiment of the invention;

FIG. 2 is a schematic cross-sectional view schematically showing a preferred exemplary embodiment of the invention;

FIG. 3 is a schematic cross-sectional view schematically showing a preferred exemplary embodiment of the invention;

FIG. 4 is a schematic cross-sectional view schematically showing a preferred exemplary embodiment of the invention;

FIG. 5 is a schematic cross-sectional view schematically showing a preferred exemplary embodiment of the invention;

FIG. 6 is a cross-sectional view of a coater 10 using a slot die 13 with which the invention is performed;

FIG. 7A shows a cross section of the slot die 13 of the invention, and FIG. 7B shows a cross section of a conventional slot die 30;

FIG. 8 is a perspective view showing the slot die 13 and portions around it in the coating step performing the invention; and

FIG. 9 is a cross-sectional view showing a pressure-reduced chamber 40 in the vicinity of a web W and the web W (a back plate 40a being integrated with the chamber 40),

Claims

1. An optical film, which comprises: a transparent support; andan optical layer on or above the transparent support,wherein the optical layer contains a thickening agent which shows a viscosity of 10 mPa·sec or more when added to 2-butanone in a content of 3% by mass, andthe optical layer has a thickness of 5 μm or more.

2. The optical film according to claim 1, wherein the thickening agent is a thixotropic agent, andthe optical layer contains the thixotropic agent in a content of from 0.01 to 5% by mass.

3. The optical film according to claim 1, wherein the thickening agent is a high molecular mass polymer of from 500,000 to 5,000,000 in mass-average molecular mass, andthe optical layer contains the high molecular polymer in a content of from 0.01 to 5% by mass.

4. The optical film according to claim 1, wherein the optical layer contains light-transmitting particles having an average particle size of from 5 to 15 μm.

5. The optical film according to claim 1, wherein the thickness of the optical layer is from 5 to 20 μm.

6. The optical film according to claim 1, which has a surface haze of 7% or less and an internal haze of 30% or less.

7. An anti-reflection film, which comprises: an optical film according to claim 1 that comprises a hard coat layer as the optical layer; anda low refractive index layer on or above the hard coat layer.

8. A process for producing an optical film, which comprises: forming an optical film according to claim 1 by coating.

9. A process for producing an anti-reflection film, which comprises: forming an anti-reflection film according to claim 7 by coating.

10. The process for producing an anti-reflection film according to claim 9, wherein the hard coat layer and the low refractive index layer are formed at once without winding up.

11. The process for producing an anti-reflection film according to claim 10, wherein the hard coat layer is coated on the transparent support using a slot die while the transparent support is allowed to run continuously on a supporting backup roller, andthe low refractive index layer is coated on the hard coat layer using a slide type coating head disposed in a vicinity of a tip of the slot die.

12. A polarizing plate, which comprises: a pair of protective films; anda polarizing film between the pair of protective films,wherein at least one of the pair of protective films is an optical film according to claim 1.

13. A polarizing plate, which comprises: a pair of protective films; anda polarizing film between the pair of protective films,wherein at least one of the pair of protective films is an anti-reflection film according to claim 7.

14. An image display device, which comprises an optical film according to claim 1 on a viewing side of a display screen.