Optical film

Abstract

To provide an optical film which is superior in terms of low moisture permeability and is suitable for a polarizing plate protection film.SOLUTION: An optical film 10 of the present invention has a laminated structure in which a resin layer 1 is laminated on one surface of a light transmissive base material 2. The resin layer 1 is formed of a cured product of a curable composition containing at least one polymerizable compound selected from a group consisting of monomers having polymerizable functional groups and oligomers having polymerizable functional groups. A value ((1,000-M1) / T) obtained by dividing a value obtained by subtracting moisture permeability M1 [g / m2 24h] of the optical film in an environment with temperature of 40°C and relative humidity of 92% from 1,000 by thickness T [μm] is 100 or greater.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical film. More specifically, it relates to an optical film suitable for a polarizer protection film.

Background Art

[0002] In an image display device (for example, a liquid crystal display device, an organic EL display device, etc.), in many cases, a polarizer is disposed on at least one side of a display cell due to its image forming method. The polarizer plays a role of passing only light with a polarization plane in a certain direction, and the performance of the image display device is greatly influenced by the performance of the polarizer. Generally, a polarizer is composed of a polyvinyl alcohol film or the like in which iodine or a dye is adsorbed and oriented, and a transparent protective film (polarizer protection film) is bonded to at least one surface of the polarizer (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, the market for mobile applications such as smartphones and tablet terminals has expanded, and the need for thinning of image display devices has increased further. Thinning of members constituting a polarizer such as a polarizer protection film is also required. However, as the thickness of the polarizer protection film decreases, there is a problem that the protection function for the polarizer deteriorates.

[0005] For example, when the polarizer protection film becomes thinner, the permeability to moisture (moisture permeability) increases, and in a humid environment, the polarization performance of the polarizer disappears, and a phenomenon called "color bleeding" may occur.

[0006] The present invention has been conceived under the above circumstances, and an object of the present invention is to provide an optical film that is excellent in low moisture permeability even when made thin and is suitable for a polarizing plate protective film.

[0007] In addition, when the polarizing plate protective film becomes thin, there are problems such as a decrease in surface hardness and scratch resistance, an increased susceptibility to damage during the manufacturing process, and a decrease in the performance of the polarizing plate such as a decrease in low moisture permeability. Therefore, the optical film used for the polarizing plate protective film is also required to be excellent in scratch resistance.

Means for Solving the Problems

[0008] That is, the first or second aspect of the present invention provides an optical film in which a resin layer is laminated on one surface of a light-transmissive substrate. The resin layer imparts excellent low moisture permeability to the optical film of the first or second aspect of the present invention. In addition, the resin layer also imparts excellent scratch resistance to the optical film of the first or second aspect of the present invention. Therefore, the optical film of the first or second aspect of the present invention having the resin layer in a laminated structure is suitable for a polarizing plate protective film.

[0009] In the optical film of the first or second aspect of the present invention, the resin layer is formed of a cured product of a curable composition containing at least one polymerizable compound selected from the group consisting of a monomer having a polymerizable functional group and an oligomer having a polymerizable functional group. This configuration is suitable for imparting excellent low moisture permeability to the optical film of the first or second aspect of the present invention. It is also suitable for imparting excellent scratch resistance to the optical film of the first or second aspect of the present invention.

[0010] In the optical film of the first aspect of the present invention, the value obtained by dividing the value obtained by subtracting the moisture permeability M 1 [g / m 2 ·24h] of the optical film at a temperature of 40°C and a relative humidity of 92% from 1,000 by the thickness T [μm] of the resin layer ((1,000 - M 1 )) / T) is 100 or more. The value ((1,000 - M 1) / T) being 100 or more is preferable in that when the optical film of the first aspect of the present invention is used as a polarizer protection film, even when the resin layer is thin, the occurrence of "color leakage" of the polarizer can be suppressed in a humid environment. From the viewpoint of achieving both suppression of the occurrence of color leakage of the polarizer and thinning of the resin layer at a higher level, the value ((1,000 - M 1 ) / T) is preferably 105 or more, more preferably 110 or more, and may be 115 or more.

[0011] In the optical film of the second aspect of the present invention, the value obtained by dividing the value obtained by subtracting the water vapor permeability M 2 [g / m 2 ·24h] at a temperature of 60°C and a relative humidity of 90% from 2,000 by the thickness T [μm] of the resin layer ((2,000 - M 2 ) / T) is 200 or more. The configuration in which the value ((2,000 - M 2 ) / T) is 200 or more is preferable in that when the optical film of the second aspect of the present invention is used as a polarizer protection film, even when the resin layer is thin, the occurrence of "color leakage" of the polarizer can be suppressed in a humid environment. From the viewpoint of achieving both suppression of the occurrence of color leakage of the polarizer and thinning of the resin layer at a higher level, the value ((2,000 - M 2 ) / T) is preferably 210 or more, more preferably 220 or more, and may be 230 or more.

[0012] In the optical film of the first or second aspect of the present invention, the product [((1,000 - M 1 ) / T) × ((2,000 - M 2 ) / T)] of the value ((1,000 - M 1 ) / T) and the value ((2,000 - M 2 ) / T) is preferably 20,000 or more. The product [((1,000 - M 1 ) / T) × ((2,000 - M 2) / T)] being 20,000 or more is preferable in that, when the optical film of the first or second aspect of the present invention is used as a polarizer protection film, even when the resin layer is thin, the occurrence of "color leakage" of the polarizer can be suppressed in a humid environment. From the viewpoint of achieving both suppression of the occurrence of color leakage of the polarizer and further thinning of the resin layer at a higher level, the above product [((1,000 - M 1 ) / T)×((2,000 - M 2 ) / T)] is preferably 21,000 or more, and more preferably 22,000 or more.

[0013] In the optical film of the first or second aspect of the present invention, it is preferable that the surface of the resin layer is not scratched when a scratch resistance test is performed using steel wool under the conditions of a load of 0.98 N, a moving speed of 100 mm / second, and 10 reciprocations. As described above, the resin layer also imparts excellent scratch resistance to the optical film of the first or second aspect of the present invention. Therefore, when the optical film of the first or second aspect of the present invention is used as a polarizer protection film, since the resin layer is excellent in scratch resistance, it is difficult to be scratched in the manufacturing process, and a decrease in the performance of the polarizer such as a decrease in the low moisture permeability performance can be suppressed.

[0014] In the optical film of the first or second aspect of the present invention, the film thickness of the resin layer is preferably 0.5 to 6 μm. As described above, even if the resin layer is made thin, excellent low moisture permeability can be imparted to the optical film of the first aspect of the present invention. From the viewpoint of being able to make the polarizer thinner when the optical film of the first or second aspect of the present invention is used as a polarizer protection film, the film thickness of the resin layer is preferably 5.8 μm or less, and more preferably 5.6 μm or less. As the lower limit value of the film thickness of the resin layer, from the viewpoint of achieving both low moisture permeability and scratch resistance at a higher level, 1 μm or more is preferable, and it may be 2 μm or more.

[0015] In the optical film according to the first aspect of the present invention, it is preferable that the light-transmissive base material contains at least one selected from the group consisting of a cellulose-based resin, a polyester-based resin, an acrylic-based resin, and a cyclic olefin-based polymer. These resins can be suitably used as the base material of a polarizing plate protection film.

[0016] Further, the third aspect of the present invention provides a polarizing plate in which a polarizer is disposed on the side opposite to the resin layer of the optical film according to the first or second aspect of the present invention. Furthermore, the fourth aspect of the present invention provides an image display device having the polarizing plate according to the third aspect of the present invention. In the image display device according to the fourth aspect of the present invention, it is preferable that an adhesive layer and an optical member are laminated in this order on the resin layer.

[0017] Since the optical film according to the first or second aspect of the present invention is used as a polarizing plate protection film in the polarizing plate according to the third aspect of the present invention, the resin layer has excellent low moisture permeability and scratch resistance even if it is thin. Therefore, the image display device according to the fourth aspect of the present invention having the polarizing plate according to the third aspect of the present invention is less likely to cause color bleeding of the polarizer and the like in a humid environment and has excellent durability even if it is thin.

Advantages of the Invention

[0018] The polarizing plate obtained by using the optical film of the present invention as a polarizing plate protection film is excellent in low moisture permeability even when thinned, is less likely to cause color bleeding of the polarizer, and has excellent durability.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Best Mode for Carrying Out the Invention

[0020] The first or second aspect of the present invention provides an optical film in which a resin layer is laminated on one surface of a light-transmissive substrate. In this specification, the optical film of the first aspect of the present invention may be referred to as "optical film A", and the optical film of the second aspect of the present invention may be referred to as "optical film B" in this specification. Further, optical film A and optical film B may be collectively referred to as "the optical film of the present invention". In this specification, the resin layer constituting optical film A may be referred to as "resin layer A", the resin layer constituting optical film B may be referred to as "resin layer B", and resin layer A and resin layer B may be collectively referred to as "the resin layer of the present invention". In addition, the light-transmissive substrate constituting the optical film of the present invention may be referred to as "the light-transmissive substrate of the present invention". Also, "film" shall include the meanings of "sheet" and "tape". That is, the optical film of the present invention may have a form on a sheet or tape.

[0021] The third aspect of the present invention provides a polarizing plate in which a polarizer is disposed on the side opposite to the resin layer of the optical film of the present invention. In this specification, the polarizing plate of the third aspect of the present invention may be referred to as "the polarizing plate of the present invention". In addition, the fourth aspect of the present invention provides an image display device having the polarizing plate of the present invention. In this specification, the image display device of the fourth aspect of the present invention may be referred to as "the image display device of the present invention".

[0022] Hereinafter, embodiments of the optical film of the present invention will be described in relation to the drawings, but the present invention is not limited thereto and is merely illustrative.

[0023] FIG. 1 is a schematic diagram (cross-sectional view) showing an embodiment of the optical film of the present invention. In FIG. 1, the optical film 10 has a laminated structure in which a resin layer 1 is laminated on one surface of a light-transmissive substrate 2.

[0024] Figure 2 is a schematic diagram (cross-sectional view) showing an embodiment of the polarizing plate of the present invention. In Figure 2, the polarizing plate 20 has a laminated structure in which a polarizer 3 is disposed on the side opposite to the resin layer 1 of the optical film 10. In this embodiment, on the side opposite to the optical film 10 of the polarizer 3, a second light-transmissive substrate 4 and an adhesive layer 5 are further laminated in this order.

[0025] Figure 3 is a schematic diagram (cross-sectional view) showing an embodiment of an image display device having the polarizing plate of Figure 2. In the image display device 30 of Figure 3, an image display panel 6 is laminated on the adhesive layer 5 of the polarizing plate 20. In this embodiment, an adhesive layer 7 and an optical member 8 are laminated in this order on the resin layer 1. Hereinafter, each component will be described.

[0026] <Optical Film> "Optical" in the optical film of the present invention means being used for optical applications, and more specifically, being used for the manufacture of products (optical products) in which optical members are used. Examples of optical products include input devices such as image display devices and touch panels, and it can be preferably used for the manufacture of liquid crystal image display devices, self-emitting type image display devices (for example, organic EL (electroluminescence) image display devices, LED image display devices), etc. More specifically, it can be preferably used as a protective film for the polarizing plate constituting the image display device.

[0027] The form of the optical film of the present invention is not particularly limited as long as a resin layer is laminated on one surface of the light-transmissive substrate. For example, the optical film of the present invention may have a resin layer on only one side or may have resin layers on both sides. Further, when the optical film of the present invention has resin layers on both sides, the optical film of the present invention may have a form in which both resin layers are provided by the resin layer of the present invention, or one resin layer may be provided by the resin layer of the present invention and the other resin layer may have a form provided by a resin layer other than the resin layer of the present invention (other resin layer). When the optical film of the present invention is used as a polarizing plate protective film, an optical film having a resin layer on only one side is preferable.

[0028] In addition to the light-transmissive substrate of the present invention and the resin layer of the present invention, the optical film of the present invention may have other layers, for example, a substrate other than the light-transmissive substrate of the present invention, a resin layer other than the resin layer of the present invention, an intermediate layer, an undercoat layer, an antistatic layer, a separator, a surface protective film, etc., on the surface or between any layers, as long as the effects of the present invention are not impaired.

[0029] In the optical film A of the present invention, the value obtained by dividing the value obtained by subtracting the water vapor permeability M 1 [g / m 2 ·24 h] of the optical film A at a temperature of 40 ° C. and a relative humidity of 92% from 1,000 by the thickness T [μm] of the resin layer A ((1,000 - M 1 ) / T) is 100 or more. The resin layer A of the present invention imparts excellent low water vapor permeability to the optical film A of the present invention. Generally, the water vapor permeability tends to increase as the film thickness increases, and the water vapor permeability tends to decrease as the film thickness decreases. The above numerical value "1,000" is an approximate value of the water vapor permeability of the light-transmissive substrate itself of the present invention (the light-transmissive substrate having no resin layer A) at a temperature of 40 ° C. and a relative humidity of 92%, and the value obtained by subtracting the water vapor permeability M 1 [g / m 2 ·24 h] from 1,000 is an approximate value of the reduced water vapor permeability due to the provision of the resin layer A on the light-transmissive substrate of the present invention. Therefore, the value ((1,000 - M 1) / T) can be an index of the moisture permeability reduction in an environment of a temperature of 40°C and a relative humidity of 92% per 1 μm thickness of the resin layer A of the present invention, and it can be said that the higher the value, the better the low moisture permeability. Therefore, the above value ((1,000 - M 1 ) / T) of 100 or more of the resin layer A of the present invention having a laminated structure in the optical film A imparts excellent low moisture permeability even when the resin layer A is thin, and has both thinness and excellent low moisture permeability.

[0030] The above value ((1,000 - M 1 ) / T) being 100 or more is a configuration that, when the optical film A of the present invention is used as a polarizer protection film, can impart excellent low moisture permeability even when the resin layer A of the present invention is thin, and is preferable in that it can suppress the occurrence of "color leakage" of the polarizer in a humid environment. From the viewpoint of achieving both suppression of the occurrence of color leakage of the polarizer and further thinning of the resin layer A of the present invention at a higher level, the above value ((1,000 - M 1 ) / T) is preferably 105 or more, more preferably 110 or more, and may be 115 or more. The upper limit value of the above value ((1,000 - M 1 ) / T)) is not particularly limited, but from the viewpoint of preventing the occurrence of "color leakage" of the polarizer by allowing the moisture in the polarizing plate to escape to the outside, it is preferably 500 or less, more preferably 400 or less, and may be 300 or less.

[0031] In the optical film B of the present invention, the value obtained by dividing the value obtained by subtracting the moisture permeability M 2 [g / m 2 ·24h] of the optical film B at a temperature of 60°C and a relative humidity of 90% from 2,000 by the thickness T [μm] of the resin layer B ((2,000 - M 2 ) / T) is 200 or more. The resin layer B of the present invention imparts excellent low moisture permeability to the optical film B of the present invention. Generally, the moisture permeability tends to increase as the film thickness increases, and the moisture permeability tends to decrease as the film thickness decreases. The above numerical value "2,000" is an approximate value of the moisture permeability of the light-transmissive substrate itself of the present invention (the light-transmissive substrate having no resin layer B) at a temperature of 60°C and a relative humidity of 90%, and from 2,000 to the moisture permeability M 2 [g / m2 · The value obtained by subtracting [24h] is an approximate value of the reduced moisture permeability due to providing the resin layer B on the light-transmissive substrate of the present invention. Therefore, the value ((2,000 - M 2 ) / T) can be an index of the moisture permeability to be reduced under the environment of a temperature of 60 ° C and a relative humidity of 90% per 1 μm thickness of the resin layer B of the present invention, and it can be said that the higher the value, the better the low moisture permeability. Therefore, the optical film B having the resin layer B of the present invention in which the value ((2,000 - M 2 ) / T) is 200 or more has excellent low moisture permeability even when the resin layer B is thin, and has both thinness and excellent low moisture permeability.

[0032] The value ((2,000 - M 2 ) / T) being 200 or more means that when the optical film B of the present invention is used as a polarizer protection film, excellent low moisture permeability can be imparted even when the resin layer B of the present invention is thin, and it is preferable in that the occurrence of "color bleeding" of the polarizer can be suppressed in a humid environment. From the viewpoint of achieving both suppression of the occurrence of color bleeding of the polarizer and further thinning of the resin layer B of the present invention at a higher level, the product value ((2,000 - M 2 ) / T) is preferably 210 or more, more preferably 220 or more, and may be 230 or more. The upper limit value of the value ((2,000 - M 2 ) / T)) is not particularly limited, but from the viewpoint of preventing the occurrence of "color bleeding" of the polarizer by allowing the moisture in the polarizing plate to escape to the outside, it is preferably 1,000 or less, more preferably 800 or less, and may be 500 or less.

[0033] In the optical film A or B of the present invention, the product [((1,000 - M 1 ) / T) × ((2,000 - M 2 ) / T)] of the value ((1,000 - M 1 ) / T) and the value ((2,000 - M 2 ) / T) is preferably 20,000 or more. The product [((1,000 - M 1 ) / T) × ((2,000 - M 2 ) / T)] is also the value ((1,000 - M 1)) / T), the value ((2,000 - M 2 )) / T) can be an index of moisture permeability provided by the resin layer (resin layer A or B) of the present invention itself, and it can be said that the higher the value, the better the low moisture permeability. Therefore, the product [((1,000 - M 1 )) / T) × ((2,000 - M 2 )) / T)] of the present invention having the resin layer A or B of the present invention in a laminated structure, the resin layer A or B of the present invention is excellent in low moisture permeability even when it is thin, and it is preferable because it has both thinness and excellent low moisture permeability.

[0034] The product [((1,000 - M 1 )) / T) × ((2,000 - M 2 )) / T)] being 20,000 or more, when the optical film A or B of the present invention is used as a polarizer protection film, even when the resin layer A or B of the present invention is thin, it is preferable in that it can suppress the occurrence of "color bleeding" of the polarizer in a humid environment. From the viewpoint of achieving both suppression of the occurrence of color bleeding of the polarizer and further thinning of the resin layer A or B of the present invention at a higher level, the above product [((1,000 - M 1 )) / T) × ((2,000 - M 2 )) / T)] is preferably 21,000 or more, more preferably 22,000 or more. The upper limit value of the [((1,000 - M 1 )) / T) × ((2,000 - M 2 )) / T)] is not particularly limited, but from the viewpoint of preventing the occurrence of "color bleeding" of the polarizer by allowing moisture in the polarizer to escape to the outside, it is preferably 200,000 or less, more preferably 150,000 or less, and may be 120,000 or less.

[0035] In the optical film (optical film A or B) of the present invention, the value obtained by subtracting the moisture permeability M 3 [g / m 2 ·24h] of the optical film at a temperature of 65 ° C and a relative humidity of 90% from 2,700 is divided by the thickness T [μm] of the resin layer (resin layer A or B), and the value ((2,700 - M 3) / T) is preferably 250 or more. The numerical value "2,700" is an approximate value of the water vapor permeability of the light-transmissive base material of the present invention itself (the light-transmissive base material having no resin layer A or B) under the environment of a temperature of 65 ° C and a relative humidity of 90%, and the water vapor permeability M is subtracted from 2,700 3 [g / m 2 ·24h], and the resulting value is an approximate value of the reduced water vapor permeability due to providing the resin layer A or B on the light-transmissive base material of the present invention. Therefore, the value ((2,700 - M 3 ) / T) can be an index of the water vapor permeability reduced per 1 μm of the thickness of the resin layer A or B of the present invention under the environment of a temperature of 65 ° C and a relative humidity of 90%, and it can be said that the higher the value, the better the low water vapor permeability. Therefore, the optical film A or B having the resin layer A or B of the present invention in a laminated structure, in which the value ((2,700 - M 3 ) / T) is 250 or more, is provided with excellent low water vapor permeability even when the resin layer A or B is thin, and has both a thin profile and excellent low water vapor permeability.

[0036] The configuration in which the value ((2,700 - M 3 ) / T) is 250 or more is preferable in that when the optical film A or B of the present invention is used as a polarizing plate protective film, excellent low water vapor permeability can be imparted even when the resin layer A or B of the present invention is thin, and the occurrence of "color bleeding" of the polarizer can be suppressed in a humid environment. From the viewpoint of achieving both suppression of the occurrence of color bleeding of the polarizer and further thinning of the resin layer A or B of the present invention at a higher level, the value ((2,700 - M 3 ) / T) is preferably 270 or more, more preferably 280 or more, and may be 300 or more. The upper limit value of the value ((2,700 - M 3 ) / T)) is not particularly limited, but from the viewpoint of preventing the occurrence of "color bleeding" of the polarizer by allowing the moisture in the polarizing plate to escape to the outside, it is preferably 1,000 or less, more preferably 800 or less, and may be 600 or less.

[0037] The water vapor permeability M of the optical film A of the present invention under the environment of a temperature of 40 ° C and a relative humidity of 92% 1 [g / m 2 ·24h] is 700 g / m 2·Preferably, it is less than 24 h. The moisture permeability M 1 is 700 g / m 2 ·The configuration of being less than 24 h is preferable in that it can suppress the occurrence of "color bleeding" of the polarizer in a humid environment when the optical film A of the present invention is used as a polarizer protection film. From the viewpoint of suppressing the occurrence of color bleeding of the polarizer at a higher level, the moisture permeability M 1 is preferably 600 g / m 2 ·24 h or less, and may be 550 g / m 2 ·24 h or less. The lower limit of the moisture permeability M 1 is not particularly limited, but from the viewpoint of preventing the occurrence of "color bleeding" of the polarizer by allowing the moisture in the polarizer to escape to the outside, it is preferably 100 g / m 2 ·24 h or more, more preferably 200 g / m 2 ·24 h or more, and may be 300 g / m 2 ·24 h or more.

[0038] The moisture permeability M of the optical film B of the present invention at a temperature of 60°C and a relative humidity of 90% environment 2 [g / m 2 ·24 h] is preferably 1,500 g / m 2 ·24 h or less. The moisture permeability M 2 being 1,500 g / m 2 ·24 h or less is preferable in that it can suppress the occurrence of "color bleeding" of the polarizer in a humid environment when the optical film B of the present invention is used as a polarizer protection film. From the viewpoint of suppressing the occurrence of color bleeding of the polarizer at a higher level, the moisture permeability M 2 is preferably 1,400 g / m 2 ·24 h or less, more preferably 1,300 g / m 2 ·24 h or less, and may be 1,200 g / m 2 ·24 h or less. The lower limit of the moisture permeability M 2 is not particularly limited, but from the viewpoint of preventing the occurrence of "color bleeding" of the polarizer by allowing the moisture in the polarizer to escape to the outside, it is preferably 300 g / m 2 ·24 h or more, more preferably 500 g / m 2 ·24 h or more, and may be 800 g / m 2· It may be 24 hours or more.

[0039] The moisture permeability M of the optical film A or B of the present invention under the environment of temperature 65°C and relative humidity 90% 3 [g / m 2 · 24h] is 2,000 g / m 2 · It is preferably 2,000 g / m 3 · 24h or less. The moisture permeability M 2 · The configuration of being 2,000 g / m 3 · 24h or less is preferable in that when the optical film A or B of the present invention is used as a polarizing plate protective film, the occurrence of "color leakage" of the polarizer can be suppressed in a humid environment. From the viewpoint of suppressing the occurrence of color leakage of the polarizer at a higher level, the moisture permeability M 2 is preferably 1,800 g / m 2 · 24h or less, more preferably 1,600 g / m 2 · 24h or less may be sufficient. The moisture permeability M 3 The lower limit value of is not particularly limited, but from the viewpoint of preventing the occurrence of "color leakage" of the polarizer by allowing the moisture in the polarizing plate to escape to the outside, 500 g / m 2 · 24h or more is preferable, 750 g / m 2 · 24h or more is more preferable, 1,000 g / m 2 · It may be 24 hours or more.

[0040] The moisture permeability M in the optical film (optical films A and B) of the present invention 1 , M 2 , M 3 , and the value ((1,000 - M 1 ) / T), the value ((2,000 - M 2 ) / T), the value ((2,700 - M 3 ) / T), and their products, etc. can be specifically measured by the method of the examples described below. The moisture permeability M in the optical film of the present invention 1 , M 2 , M 3 , and the value ((1,000 - M 1 ) / T), the value ((2,000 - M 2 ) / T), the value ((2,700 - M 3) / T), and their products, etc., can be adjusted by adjusting the type and thickness of the resin constituting the light-transmissive substrate of the present invention, the type, composition, crosslinking degree, etc. of the resin constituting the resin layers (resin layers A and B) of the present invention.

[0041] The haze of the optical film of the present invention is not particularly limited, but from the viewpoint of obtaining good transparency, it is preferably 1.0% or less, more preferably 0.8% or less. The haze can be determined in accordance with JIS K 7136 (2000). The haze of the optical film of the present invention can be adjusted by the type and thickness of the resin constituting the light-transmissive substrate of the present invention, the type and thickness of the resin constituting the resin layer of the present invention, and the like.

[0042] The total light transmittance in the visible light wavelength region of the optical film of the present invention is not particularly limited, but is preferably 85% or more, more preferably 88% or more. The visible light wavelength region can be determined in accordance with JIS K 7361-1. The total light transmittance of the optical film of the present invention can be adjusted by the type and thickness of the resin constituting the light-transmissive substrate of the present invention, the type and thickness of the resin constituting the resin layer of the present invention, and the like.

[0043] The thickness of the optical film of the present invention is not particularly limited, but for example, considering workability such as thin layer properties, strength, and handleability, the range of 1 to 500 μm is preferable, more preferably the range of 10 to 300 μm, and most preferably the range of 20 to 200 μm.

[0044] <Light-transmissive substrate> Examples of the material constituting the light-transmissive substrate of the present invention include glass and plastic films. Examples of the plastic film include cellulose resins such as triacetyl cellulose (TAC), acrylic resins such as polymethyl methacrylate (PMMA), polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), cyclic olefin polymers (COP) (for example, trade name "ARTON" (manufactured by JSR Corporation), trade name "ZEONOR" (manufactured by Zeon Corporation), etc.), polycarbonate resins, polysulfone resins, polyarylate resins, polyimide resins, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymers, and other plastic materials. From the viewpoints of optical uniformity, smooth surface, and good secondary processability in manufacturing a polarizing plate, cellulose resins, acrylic resins, polyester resins, and cyclic olefin polymers (COP) are preferred, and cellulose resins are particularly preferred. These plastic materials can be used alone or in combination of two or more.

[0045] The haze of the light-transmissive substrate of the present invention is not particularly limited, but from the viewpoint of obtaining good transparency, it is preferably 1.0% or less, more preferably 0.8% or less. The haze can be determined in accordance with JIS K 7136 (2000). The haze of the light-transmissive substrate of the present invention can be adjusted by the type and thickness of the resin constituting the light-transmissive substrate of the present invention.

[0046] The total light transmittance in the visible light wavelength region of the light-transmissive substrate of the present invention is not particularly limited, but is preferably 85% or more, more preferably 88% or more. The visible light wavelength region can be determined in accordance with JIS K 7361-1. The total light transmittance of the light-transmissive substrate of the present invention can be adjusted by the type and thickness of the resin constituting the light-transmissive substrate of the present invention.

[0047] The thickness of the light-transmissive substrate of the present invention is not particularly limited. However, considering workability such as thin layer properties, strength, and handleability, and thin layer properties, etc., a range of 1 to 500 μm is preferable, more preferably a range of 10 to 300 μm, and optimally a range of 20 to 200 μm.

[0048] The refractive index of the light-transmissive substrate of the present invention is not particularly limited. For example, it is in the range of 1.30 to 1.80, preferably in the range of 1.40 to 1.70. Further, on the surface of the light-transmissive substrate of the present invention (the surface on which the resin layer is formed and / or the opposite surface), known and commonly used surface treatments such as physical treatments such as corona discharge treatment and plasma treatment, and chemical treatments such as undercoat treatment may be appropriately applied.

[0049] <Resin layer> The resin layer (resin layers A and B) of the present invention is laminated on one surface of the light-transmissive substrate of the present invention and imparts excellent low moisture permeability to the optical film of the present invention. Further, the resin layer of the present invention also imparts excellent scratch resistance to the optical film of the present invention. Therefore, the optical film of the present invention having the resin layer in a laminated structure can be suitably used as a polarizing plate protective film.

[0050] It is preferable that the surface of the resin layer of the present invention is not scratched when a scratch resistance test is performed under the conditions of a load of 0.98 N, a moving speed of 100 mm / second, and 10 reciprocations using steel wool. That is, since the optical film of the present invention is coated with the resin layer of the present invention having excellent scratch resistance, it is less likely to be scratched in the manufacturing process even when made thin, and can provide a polarizing plate having excellent durability when used as a polarizing plate protective film. The excellent scratch resistance of the resin layer of the present invention can be imparted by adjusting the composition and thickness described below that constitute the resin layer.

[0051] The resin layer of the present invention is formed of a cured product of a curable composition containing at least one polymerizable compound selected from the group consisting of a monomer having a polymerizable functional group and an oligomer having a polymerizable functional group. The polymerizable compound constituting the resin layer of the present invention may be referred to as "the polymerizable compound of the present invention" in this specification, and the curable composition containing the polymerizable compound of the present invention may be referred to as "the curable composition of the present invention". The configuration that the resin layer of the present invention is formed of a cured product of the curable composition of the present invention containing the polymerizable compound of the present invention is preferable in that it can impart excellent low moisture permeability and scratch resistance to the optical film of the present invention.

[0052] The "polymerizable functional group" possessed by the polymerizable compound of the present invention is not particularly limited, and examples thereof include an unsaturated double bond group, an epoxy group, an oxetanyl group, etc. From the viewpoint of excellent low moisture permeability and scratch resistance, an unsaturated double bond group is preferable. Examples of the unsaturated double bond group include a (meth)acryloyl group, a vinyl group, a styryl group, an allyl group, etc. Among them, a (meth)acryloyl group is preferable. In this specification, "(meth)acryloyl" represents either one or both of "acryloyl" and "methacryloyl", and "(meth)acrylic" also represents either one or both of "acrylic" and "methacrylic".

[0053] The number of "polymerizable functional groups" possessed by the polymerizable compound of the present invention is not particularly limited as long as it is 1 or more. However, in terms of imparting excellent low moisture permeability and scratch resistance to the optical film of the present invention, the curable composition of the present invention preferably contains at least a polymerizable compound having 2 or more, more preferably 3 or more, still more preferably 4 or more, or alternatively, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or 10 or more polymerizable functional groups. The upper limit of the number of "polymerizable functional groups" is not particularly limited, but it may be 30 or less, 25 or less, or 20 or less.

[0054] In order to impart excellent low moisture permeability to the optical film of the present invention, the curable composition of the present invention preferably contains, as the polymerizable compound of the present invention, a compound having an alicyclic hydrocarbon group and an unsaturated double bond group in the molecule (hereinafter sometimes referred to as "polymerizable compound A"). It is considered that the alicyclic hydrocarbon group contained in the polymerizable compound A hydrophobizes the resin layer of the present invention and reduces the moisture permeability. The curable composition of the present invention may contain one type of polymerizable compound A or may contain two or more types of polymerizable compound A.

[0055] As the polymerizable functional group of the polymerizable compound A, an unsaturated double bond group such as a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group is preferable, and among them, a (meth)acryloyl group is preferable. Particularly preferred are compounds containing two or more (meth)acryloyl groups in one molecule as described below.

[0056] The number of "polymerizable functional groups" contained in the polymerizable compound A is not particularly limited as long as it is 1 or more, but in terms of imparting excellent low moisture permeability and scratch resistance to the optical film of the present invention, the polymerizable functional group preferably has 2 or more, more preferably 3 or more, and even more preferably 4 or more. The upper limit of the number of "polymerizable functional groups" of the polymerizable compound A is not particularly limited, but it may be 10 or less, 9 or less, or 8 or less.

[0057] The "alicyclic hydrocarbon group" contained in the polymerizable compound A is preferably a group derived from an alicyclic compound having 7 or more carbon atoms, more preferably a group derived from an alicyclic compound having 10 or more carbon atoms, and even more preferably a group derived from an alicyclic compound having 12 or more carbon atoms. As the alicyclic hydrocarbon group, a group derived from a polycyclic compound such as a bicyclic or tricyclic compound is particularly preferable.

[0058] As the alicyclic hydrocarbon group (including the linking group), a group represented by any of the following general formulas (I) to (V) is preferable, a group represented by the following general formulas (I), (II), or (IV) is more preferable, and a group represented by the following general formula (I) is even more preferable. [Chem.]

[0059] In general formula (I), L and L' each independently represent a divalent or higher linking group. n represents an integer from 1 to 3. [Chem.]

[0060] In general formula (II), L and L' each independently represent a divalent or higher linking group. n represents an integer from 1 to 2. [Chem.]

[0061] In general formula (III), L and L' each independently represent a divalent or higher linking group. n represents an integer from 1 to 2. [Chem.]

[0062] In general formula (IV), L and L' each independently represent a divalent or higher linking group, and L" represents a hydrogen atom or a divalent or higher linking group. [Chem.]

[0063] In general formula (V), L and L' each independently represent a divalent or higher linking group.

[0064] Specific examples of the cycloaliphatic hydrocarbon group include monovalent to trivalent groups derived from norbornane, tricyclodecane, tetracyclododecane, pentacyclopentadecane, adamantane, diamantane, etc.

[0065] The polymerizable compound A containing a group represented by any of the above general formulas (I) to (V) as an alicyclic hydrocarbon group has a polymerizable functional group via a linking group represented by L, L', and L". Examples of the linking group include a single bond, an optionally substituted alkylene group having 1 to 6 carbon atoms, an amide group in which the N-position may be disubstituted, a carbamoyl group in which the N-position may be substituted, an ester group, an oxycarbonyl group, an ether group, etc., and groups obtained by combining these.

[0066] The polymerizable compound A can be easily synthesized, for example, by a one-step or two-step reaction of a polyol such as a diol or triol having the above alicyclic hydrocarbon group with a carboxylic acid, carboxylic acid derivative, epoxy derivative, isocyanate derivative, etc. of a compound having a (meth)acryloyl group, vinyl group, styryl group, allyl group, etc. Preferably, it can be synthesized by reacting with a polyol having the above alicyclic hydrocarbon group using (meth)acrylic acid, (meth)acryloyl chloride, (meth)acrylic anhydride, glycidyl (meth)acrylate, 1,1-bis(acryloxymethyl)ethyl isocyanate, etc.

[0067] Hereinafter, preferred specific examples of the polymerizable compound A are shown, but the present invention is not limited thereto.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0068] The content of the polymerizable compound A in the curable composition of the present invention is not particularly limited. However, from the viewpoint of imparting excellent low moisture permeability to the resin layer of the present invention, based on 100% by weight of the non-volatile solid content of the curable composition of the present invention, 10% by weight or more is preferable, 15% by weight or more is more preferable, or it may be 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, 55% by weight or more, 60% by weight or more, 65% by weight or more, 70% by weight or more, 75% by weight or more, 80% by weight or more, 85% by weight or more, or 90% by weight or more. On the other hand, from the viewpoint of achieving both low moisture permeability and scratch resistance at a higher level in the resin layer of the present invention, it may be 95% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, 60% by weight or less, 55% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, 15% by weight or less, or 10% by weight or less.

[0069] In addition to excellent low moisture permeability of the optical film of the present invention, in order to impart excellent scratch resistance, the curable composition of the present invention preferably further contains, in addition to the polymerizable compound A, a polymerizable compound other than the polymerizable compound A, that is, a compound having no alicyclic hydrocarbon group in the molecule and having a polymerizable functional group (hereinafter sometimes referred to as "polymerizable compound B"). The polymerizable compound A tends to have a low crosslinking density due to the three-dimensional structure of the alicyclic hydrocarbon group in the molecule. It is considered that when the curable composition of the present invention contains the polymerizable compound B in addition to the polymerizable compound A, the crosslinking density increases and the scratch resistance is improved.

[0070] As the polymerizable functional group of the polymerizable compound B, an unsaturated double bond group such as a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group is preferable. Among them, a (meth)acryloyl group is preferable. Particularly preferable examples include compounds containing two or more (meth)acryloyl groups in one molecule as follows.

[0071] The number of "polymerizable functional groups" possessed by the polymerizable compound B is not particularly limited as long as it is 1 or more, but from the viewpoint of imparting excellent scratch resistance to the optical film of the present invention, it is preferably 2 or more, more preferably 3 or more, still more preferably 4 or more, or preferably 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or 10 or more. The upper limit of the number of "polymerizable functional groups" possessed by the polymerizable compound B is not particularly limited, but it may be 30 or less, 25 or less, or 20 or less.

[0072] Examples of the polymerizable compound B include a monomer having no alicyclic hydrocarbon group in the molecule and having a polymerizable functional group (hereinafter sometimes referred to as "polymerizable monomer B"), and an oligomer having no alicyclic hydrocarbon group in the molecule and having a polymerizable functional group (hereinafter sometimes referred to as "polymerizable oligomer B"). The curable composition of the present invention may contain only a polymerizable monomer as the polymerizable compound B, may contain only a polymerizable oligomer B, or may contain both a polymerizable monomer B and a polymerizable oligomer B. From the viewpoint of forming a high crosslink density, it is preferable to contain at least a polymerizable oligomer B.

[0073] Examples of the polymerizable monomer B include hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol (meth)hexaacrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, and the like. The curable composition of the present invention may contain one type of polymerizable monomer B or may contain two or more types of polymerizable monomer B.

[0074] The polymerizable oligomer B contains two or more repeating units and has polymerizable functional groups. That is, the polymerizable oligomer B is a polymer having polymerizable functional groups in the molecule. Examples of the polymerizable oligomer B include urethane (meth)acrylate obtained by adding two or more (meth)acryloyl groups as functional groups to the urethane skeleton, polyester (meth)acrylate obtained by adding two or more (meth)acryloyl groups as functional groups to the polyester skeleton, and epoxy (meth)acrylate obtained by adding two or more (meth)acryloyl groups as functional groups to the epoxy skeleton. From the viewpoint of forming a high crosslinking density, it is preferable to contain at least urethane (meth)acrylate. The curable composition of the present invention may contain one type of polymerizable oligomer B or two or more types of polymerizable oligomer B.

[0075] Urethane (meth)acrylate can be obtained, for example, by reacting a polyol, an isocyanate, and hydroxy (meth)acrylate. As the polyol constituting the urethane (meth)acrylate, known polyols can be used without limitation. From the viewpoint of improving the crosslinking density, a polyol having three or more (preferably four or more, more preferably five or more, still more preferably six or more) hydroxyl groups is preferable, and examples include trimethylolpropane, ethoxylated isocyanuric acid, pentaerythritol, dipentaerythritol, tripentaerythritol, and tetrapentaerythritol. These polyols may be used alone or in combination of two or more.

[0076] As the isocyanate constituting the urethane (meth)acrylate, polyisocyanates composed of linear saturated hydrocarbons, cyclic saturated hydrocarbons, and aromatic hydrocarbons can be used. Examples of such polyisocyanates include linear saturated hydrocarbon isocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate; cyclic saturated hydrocarbon isocyanates such as isophorone diisocyanate, dicyclohexylmethane diisocyanate, methylene bis(4-cyclohexyl isocyanate), hydrogenated diphenylmethane diisocyanate, hydrogenated xylene diisocyanate, and hydrogenated toluene diisocyanate; and aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 1,3-xylylene diisocyanate, p-phenylene diisocyanate, 3,3'-dimethyl-4,4'-diisocyanate, 6-isopropyl-1,3-phenyl diisocyanate, and 1,5-naphthalene diisocyanate. Preferred specific examples include isophorone diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate. These polyisocyanates may be used alone or in combination of two or more.

[0077] Examples of the hydroxy (meth)acrylate constituting the urethane (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. These hydroxy (meth)acrylates may be used alone or in combination of two or more.

[0078] Examples of urethane (meth)acrylates include the Art Resin UN series manufactured by Negami Kogyo Co., Ltd., the NK Oligo U series manufactured by Shin-Nakamura Chemical Co., Ltd., and the Purple Light UV series manufactured by Mitsubishi Chemical Corporation.

[0079] Polyester (meth)acrylate is obtained, for example, by reacting (meth)acrylic acid with the terminal hydroxyl groups of a polyester obtained by polymerizing a polyol and a polyvalent carboxylic acid. Specific examples of the polyester (meth)acrylate include Aronix M-6000, Aronix M-7000, Aronix M-8000, and Aronix M-9000 manufactured by Toagosei Co., Ltd.

[0080] Epoxy (meth)acrylate is obtained, for example, by reacting (meth)acrylic acid with an epoxy resin. Specific examples of the epoxy (meth)acrylate include Lipoxy SP and Lipoxy VR manufactured by Showa Highpolymer Co., Ltd., and the epoxy ester series manufactured by Kyoeisha Chemical Co., Ltd.

[0081] The weight average molecular weight of the polymerizable oligomer B is not particularly limited, but from the viewpoint of improving the scratch resistance of the resin layer of the present invention, it is preferably 400 or more, more preferably 500 or more, still more preferably 600 or more, and particularly preferably 700 or more. Also, from the viewpoint of the coatability of the curable composition of the present invention, etc., the weight average molecular weight of the polymerizable oligomer B is preferably 10000 or less, more preferably 7000 or less, still more preferably 5000 or less. The weight average molecular weight of the polymerizable oligomer B can be determined, for example, by high performance liquid chromatography (HPLC). For example, using HPLC8020 manufactured by Tosoh Corporation as the apparatus, using two TSKgel GMH-H(20) connected in series as the column, using tetrahydrofuran as the solvent, and measuring the weight average molecular weight under the condition of a flow rate of 0.5 mL / min.

[0082] The content of the polymerizable compound B in the curable composition of the present invention is not particularly limited. However, from the viewpoint of imparting excellent scratch resistance to the resin layer of the present invention, based on 100% by weight of the non-volatile solid content of the curable composition of the present invention, 5% by weight or more is preferable, 10% by weight or more is more preferable, 15% by weight or more is further preferable, or it may be 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, 55% by weight or more, 60% by weight or more, 65% by weight or more, 70% by weight or more, 75% by weight or more, 80% by weight or more, 85% by weight or more, or 90% by weight or more. On the other hand, from the viewpoint of achieving both low moisture permeability and scratch resistance at a higher level in the resin layer of the present invention, it may be 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, 60% by weight or less, 55% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, or 5% by weight or less.

[0083] When the curable composition of the present invention contains the polymerizable compound A and the polymerizable compound B, the ratio (polymerizable compound A / polymerizable compound B) is preferably 10 / 90 or more, more preferably 15 / 85 or more, or may be 20 / 80 or more, 25 / 75 or more, 30 / 70 or more, 35 / 65 or more, 40 / 60 or more, 45 / 55 or more, 50 / 50 or more, 55 / 45 or more, 60 / 40 or more, 65 / 35 or more, 70 / 30 or more, 75 / 25 or more, 80 / 20 or more, 85 / 15 or more, or 90 / 10 or more from the viewpoint of imparting excellent low moisture permeability to the resin layer of the present invention. On the other hand, from the viewpoint of achieving both low moisture permeability and scratch resistance at a higher level in the resin layer of the present invention, it may be 95 / 5 or less, 90 / 10 or less, 85 / 15 or less, 80 / 20 or less, 75 / 25 or less, 70 / 30 or less, 65 / 35 or less, 60 / 40 or less, 55 / 45 or less, 50 / 50 or less, 45 / 55 or less, 40 / 60 or less, 35 / 65 or less, 30 / 70 or less, 25 / 75 or less, 15 / 85 or less, or 10 / 90 or less.

[0084] The curable composition of the present invention preferably contains a polymerization initiator, and a photoinitiator is preferably used as the polymerization initiator. Examples of the photoinitiator include benzophenone-based compounds such as benzyl, benzophenone, benzoyl benzoic acid, 3,3'-dimethyl-4-methoxybenzophenone; aromatic ketone compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, α-hydroxycyclohexyl phenyl ketone; acetophenone-based compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropan-1; benzoin alkyl ether-based compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, anisoin methyl ether; aromatic ketal-based compounds such as benzyldimethyl ketal; aromatic sulfonyl chloride-based compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime-based compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; thioxanthone-based compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone; camphorquinone; halogenated ketones; acylphosphine oxides; acylphosphonates and the like. These polymerization initiators may be used alone or in combination of two or more.

[0085] The content of the photopolymerization initiator in the curable composition of the present invention is not particularly limited. However, from the viewpoint of sufficiently obtaining low moisture permeability and scratch resistance of the resin layer of the present invention, it is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and still more preferably 0.2 parts by weight or more with respect to 100 parts by weight of the polymerizable compound (the total of polymerizable compound A and polymerizable compound B). Further, from the viewpoint of suppressing the problem that the curing of the curable composition of the present invention does not occur sufficiently due to excessive radiation absorption by the photopolymerization initiator, it is preferably 10 parts by weight or less, more preferably 8 parts by weight or less with respect to 100 parts by weight of the polymerizable compound (the total of polymerizable compound A and polymerizable compound B).

[0086] Various leveling agents can be added to the curable composition of the present invention. As the leveling agent, for the purpose of preventing coating unevenness (equalizing the coating surface), for example, a fluorine-based or silicone-based leveling agent can be used. A leveling agent can also be appropriately blended when antifouling properties are required on the surface of the resin layer of the present invention. The blending amount of the leveling agent is, for example, 5 parts by weight or less, preferably in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the polymerizable compound (the total of polymerizable compound A and polymerizable compound B).

[0087] The curable composition of the present invention can contain a solvent. As the solvent, various solvents can be used in consideration of the solubility of the polymerizable compound (polymerizable compound A and / or polymerizable compound B), the drying property during coating, etc. Examples of such organic solvents include dibutyl ether, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, anisole, phenetole, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, acetone, methyl ethyl ketone (MEK), diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, methyl 2-methoxyacetate, methyl 2-ethoxyacetate, ethyl 2-ethoxyacetate, ethyl 2-ethoxypropionate, 2-methoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 1,2-diacetoxyacetone, acetylacetone, diacetone alcohol, methyl acetoacetate, ethyl acetoacetate, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, cyclohexyl alcohol, isobutyl acetate, methyl isobutyl ketone (MIBK), 2-octanone, 2-pentanone, 2-hexanone, ethylene glycol ethyl ether, ethylene glycol isopropyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, ethyl carbitol, butyl carbitol, hexane, heptane, octane, cyclohexane, methylcyclohexane, ethylcyclohexane, benzene, toluene, xylene, etc. These can be used alone or in combination of two or more kinds.

[0088] The curable composition of the present invention may further contain any appropriate additives such as a plasticizer, a surfactant, an antioxidant, an ultraviolet absorber, a thixotropic agent, an antistatic agent, etc., as long as the effects of the present invention are not impaired, if necessary.

[0089] The film thickness of the resin layer of the present invention is preferably 0.5 to 6 μm. As described above, even if the resin layer is made thin, excellent low moisture permeability can be imparted to the optical film of the present invention. From the viewpoint that the polarizing plate can be made thinner when the optical film of the present invention is used as a polarizing plate protective film, the film thickness of the resin layer is preferably 5.8 μm or less, more preferably 5.6 μm or less. As the lower limit value of the film thickness of the resin layer, from the viewpoint of achieving both low moisture permeability and scratch resistance at a higher level, 1 μm or more is preferable, and 2 μm or more may be used. The resin layer of the present invention may be a single layer or a plurality of layers may be provided. When the resin layer of the present invention is composed of a plurality of layers, the film thickness of the resin layer of the present invention is the sum of each layer constituting the plurality of layers.

[0090] The resin layer of the present invention can be formed by mixing the polymerizable compound (polymerizable compound A and / or polymerizable compound B) of the present invention with a photopolymerization initiator, a leveling agent, a solvent, other additives, etc. as necessary to prepare a coating solution (the curable composition of the present invention), applying the coating solution to one surface of a light-transmissive substrate, drying it, and curing the coating film.

[0091] The solid content concentration of the coating solution is preferably 1% by weight to 70% by weight, more preferably 2% by weight to 50% by weight, and even more preferably 5% by weight to 40% by weight.

[0092] Examples of the coating method of the coating solution include a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method, a die coating method, an extrusion coating, a bar coating method, etc.

[0093] The curing of the coating film is appropriately selected according to the type of the curable composition and the like. When the curable composition is photocurable, it can be cured by irradiating light using a light source that emits light of a wavelength as required. As the light to be irradiated, for example, light with an exposure amount of 150 mJ / cm 2 or more, preferably 200 mJ / cm 2 to 1000 mJ / cm 2Light can be used. Further, heating may be performed during the photocuring treatment. Examples of the light include ionizing radiation such as α-rays, β-rays, γ-rays, neutron rays, and electron beams, and ultraviolet rays, with ultraviolet rays being particularly preferred. Further, the irradiation time, irradiation method, etc. are not particularly limited as long as the photopolymerization initiator can be activated to cause a reaction of the polymerizable compound.

[0094] <Polarizing plate> The polarizing plate of the present invention has a laminated structure in which a polarizer is disposed on the side opposite to the resin layer of the optical film of the present invention. In FIG. 2, the polarizing plate 20 has a laminated structure in which a polarizer 3 is disposed on the side opposite to the resin layer 1 of the optical film 10. Since the optical film 10 is used as a polarizing plate protective film, the polarizing plate 20 has excellent low moisture permeability and abrasion resistance even when the resin layer 1 is thin, and quality deterioration such as color bleeding of the polarizer 3 is less likely to occur. In the present embodiment, a second light transmissive substrate 4 and an adhesive layer 5 are further laminated in this order on the side of the polarizer 3 opposite to the optical film 10.

[0095] The polarizer 3 is an element that transmits only light with a polarized wave surface in a certain direction, and known ones can be used without limitation. For example, a polyvinyl alcohol-based polarizing film can be used. The polyvinyl alcohol-based polarizing film may be a polyvinyl alcohol-based film dyed with iodine or a dichroic dye.

[0096] The polyvinyl alcohol-based polarizing film may be a film obtained by uniaxially stretching a polyvinyl alcohol-based film and then dyeing it with iodine or a dichroic dye (preferably a film further subjected to a durability treatment with a boron compound); or a film obtained by dyeing a polyvinyl alcohol-based film with iodine or a dichroic dye and then uniaxially stretching it (preferably a film further subjected to a durability treatment with a boron compound). The absorption axis of the polarizer is parallel to the stretching direction of the film.

[0097] The thickness of the polarizer 3 is preferably 5 to 25 μm, and more preferably 10 to 15 μm from the viewpoint of thinning the polarizing plate 20.

[0098] The second light transmissive substrate 4 protects the side of the optical film 10 of the polarizer 3 opposite thereto (polarizing plate protective film), and the same glass, plastic film, etc. as the light transmissive substrate of the present invention can be used. Cellulose resins, cyclic olefin polymers (COP), and polycarbonate resins are preferred, and cyclic olefin polymers (COP) and polycarbonate resins are more preferred. The light transmissive substrate 4 may be made of the same material as the light transmissive substrate 2 or may be made of different materials. The light transmissive substrate 4 may have the resin layer 1 laminated thereon or may not have the resin layer 1. Further, the light transmissive substrate 4 may be composed of a single layer or may have a laminated structure of two or more layers that are the same or different.

[0099] Also, the light transmissive substrate 4 is preferably an optical compensation film (retardation film) having an optical compensation layer including an optically anisotropic layer. The optical compensation film can improve, for example, the viewing angle characteristics of a liquid crystal display screen. As the optical compensation film, known ones can be used without limitation. For example, the retardation film described in JP-A-2014-194484 may be used.

[0100] The thickness of the light transmissive substrate 4 is preferably 5 to 25 μm, and more preferably 10 to 15 μm from the viewpoint of thinning the polarizing plate 20.

[0101] The adhesive layer 5 is formed of any suitable adhesive. Examples of the material constituting the adhesive layer 5 include materials based on polymers such as acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine-based polymers, rubber-based polymers, isocyanate-based polymers, polyvinyl alcohol-based polymers, gelatin-based polymers, vinyl-based polymers, latex-based polymers, and aqueous polyesters. Among them, materials based on acrylic polymers and / or rubber-based polymers as the base polymer are preferred from the viewpoint of low moisture permeability. The adhesive layer 5 may contain a single base polymer or two or more base polymers.

[0102] The thickness of the adhesive layer 5 is preferably 5 to 25 μm, and more preferably 10 to 20 μm from the viewpoint of thinning the polarizing plate 20.

[0103] The polarizing plate 20 can be obtained by bonding the polarizer 1 and the optical film 10 through an adhesive. Also, the polarizer 1 and the light-transmissive substrate 4 can be bonded through an adhesive. The adhesive used for bonding may be a fully saponified polyvinyl alcohol aqueous solution (water paste), or may be performed using an active energy ray curable adhesive.

[0104] The adhesive layer 5 can be formed by applying an adhesive composition containing the base polymer constituting the adhesive to the light-transmissive substrate 4, drying, and curing as necessary. Alternatively, the adhesive layer 5 may be formed on a separator in the same manner and then attached and transferred to the light-transmissive substrate 4.

[0105] Layers other than the polarizing plate 20, the optical film 10, the polarizing plate 3, the light-transmissive substrate 4, and the adhesive layer 5 (for example, a surface protection film, a separator, etc.) may be provided on the surface or between any layers. For example, the surface of the adhesive layer 5 may be protected by a separator, and the surface of the resin layer 1 of the optical film 10 may be protected by a surface protection film.

[0106] The thickness of the polarizing plate 20 (total thickness including the light-transmissive base material 4 and the adhesive layer 5) is preferably 50 to 100 μm, and more preferably 60 to 75 μm from the viewpoint of thinning the polarizing plate 20.

[0107] <Image display device> The image display device of the present invention has the polarizing plate of the present invention. Since the image display device of the present invention has the polarizing plate of the present invention in the laminated structure, even if the resin layer 1 is thin, it has excellent low moisture permeability and scratch resistance, and quality deterioration such as color bleeding of the polarizer 3 hardly occurs. Therefore, the image display device of the present invention hardly causes color bleeding or the like of the polarizing plate even in a thin form in a humid environment, and has excellent durability. In FIG. 3, in the image display device 30, an image display panel 6 is laminated on the adhesive layer 5 of the polarizing plate 20. In the present embodiment, an adhesive layer 7 and an optical member 8 are laminated on the resin layer 1 in this order.

[0108] The image display panel 6 is not particularly limited, and examples thereof include a liquid crystal image display panel and a self-emitting type image display panel (for example, an organic EL (electroluminescence) image display panel, an LED image display panel).

[0109] The image display panel 6 is formed by alternately arranging RGB elements, and in order to improve the contrast, it is preferable that the space between the RGB elements is filled with a black matrix (BM).

[0110] As the adhesive layer 7, a material containing the same base polymer as those exemplified in the adhesive layer 5 can be used. Among them, a material having an acrylic polymer and / or a rubber-based polymer as a base polymer is preferable from the viewpoint of low moisture permeability. The adhesive layer 7 may contain a single base polymer or may contain two or more base polymers. The adhesive layer 7 may be composed of the same material as the adhesive layer 5 or may be composed of a different material.

[0111] The optical member 8 can be made of the same glass, plastic film, etc. as the light-transmissive base material of the present invention, and acrylic resins, polyester resins, and cyclic olefin polymers (COP) are preferred, with polyester resins being particularly preferred. When the optical member 8 is located on the outermost surface on the viewing side of the image display device 30, it functions as a cover member.

[0112] The image display device 30 may include optical members other than the optical film 10, polarizing plate 3, light-transmissive base material 4, adhesive layer 5, image display panel 6, adhesive layer 7, and optical member 8 on the surface or between arbitrary layers. The optical members are not particularly limited, and examples include polarizing plates other than the polarizing plate 3, retardation plates, antireflection films, viewing angle adjustment films, optical compensation films, etc. The optical members shall also include members (such as design films, decorative films, and surface protection plates) that play a role in decoration and protection while maintaining the visibility of the image display device and input device.

[0113] The image display device 30 can be manufactured by laminating an optical film in which the image display panel 6, polarizing plate 20, optical member 8, and adhesive layer 7 are laminated, and specifically, it can be carried out by laminating under heating and / or pressure. After laminating under heating and / or pressure, it may be irradiated with active energy rays for curing. The irradiation of active energy rays can be carried out in the same manner as the formation of the resin layer of the present invention.

Examples

[0114] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by these examples.

[0115] Example 1 (Preparation of Coating Liquid for Resin Layer Formation) As the resin contained in the resin layer, 50 parts by weight (in terms of solid content) of an ultraviolet-curable acrylate resin (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name "A-DCP", solid content 100%) and 50 parts by weight (in terms of solid content) of an ultraviolet-curable acrylate resin (manufactured by Mitsubishi Chemical Corporation, trade name "UV-1700TL", solid content 80%) were prepared. Per 100 parts by weight of the resin solid content of the resin, 5 parts by weight of a photoinitiator (manufactured by BASF, trade name "OMNIRAD907") and 0.2 parts by weight of a leveling agent (manufactured by Kyoeisha Chemical Co., Ltd., trade name "LE-303", solid content 40%) were mixed. This mixture was diluted with a MIBK / cyclopentanone mixed solvent (weight ratio 60 / 40) so that the solid content concentration became 30% to prepare a coating liquid for forming a resin layer.

[0116] (Preparation of Optical Film) As a light-transmissive substrate, a transparent plastic film substrate (TAC, manufactured by Fuji Film Co., Ltd., trade name "TJ25UL") was prepared. On one side of the transparent plastic film substrate, the coating liquid for forming a resin layer prepared above was used to form a coating film using a bar coater #7. Then, the transparent plastic film substrate on which this coating film was formed was conveyed to a drying process. In the drying process, the coating film was dried by heating at 60°C for 1 minute. Thereafter, ultraviolet rays with an integrated light amount of 220 mJ / cm 2 were irradiated with a high-pressure mercury lamp to cure the coating film and form a resin layer with a thickness of 2.5 μm, and the optical film 1 of Example 1 was obtained. The details of the resin used in Example 1 are as follows. ·A-DCP: Tricyclodecane dimethanol dimethacrylate ·UV-1700TL: 10-functional urethane acrylate

[0117] Example 2 An optical film 2 of Example 2 was obtained in the same manner as in Example 1, except that a coating film was formed using a bar coater #14.

[0118] Example 3 Example 3 optical film 3 was obtained in the same manner as in Example 1, except that 70 parts by weight (in terms of solid content) of A-DCP and 30 parts by weight (in terms of solid content) of UV-1700TL were blended as the resin contained in the resin layer.

[0119] Example 4 Example 4 optical film 4 was obtained in the same manner as in Example 1, except that 70 parts by weight (in terms of solid content) of A-DCP and 30 parts by weight (in terms of solid content) of UV-1700TL were blended as the resin contained in the resin layer, and a coating film was formed using a bar coater #14.

[0120] Example 5 Example 5 optical film 3 was obtained in the same manner as in Example 1, except that 0.1 part by weight of a leveling agent was blended in the resin layer and the integrated light quantity was set to 260 mJ / cm 2 Example 5 optical film 3 was obtained in the same manner as in Example 1, except that 0.1 part by weight of a leveling agent was blended in the resin layer and the integrated light quantity was set to 260 mJ / cm

[0121] Comparative Example 1 As the resin contained in the resin layer, 40 parts by weight (in terms of solid content) of an ultraviolet curable acrylate resin (manufactured by Toagosei Co., Ltd., trade name "M-920", solid content 100%) and 60 parts by weight (in terms of solid content) of UV-1700TL were prepared, and 3 parts by weight of OMNIRAD907 and 0.2 part by weight of LE-303 were mixed. This mixture was diluted with a MIBK / cyclopentanone mixed solvent (weight ratio 70 / 30) so that the solid content concentration became 30% to prepare and blend a coating liquid for forming a resin layer. Comparative Example 1 optical film 6 was obtained in the same manner as in Example 1, except that the coating liquid for forming a resin layer prepared above was used to form a coating film using a bar coater #6.

[0122] Comparative Example 2 As the resin contained in the resin layer, 40 parts by weight (in terms of solid content) of an ultraviolet-curable acrylate resin (manufactured by Toagosei Co., Ltd., trade name "M-920", solid content 100%) and 60 parts by weight (in terms of solid content) of UV-1700TL were prepared, and 3 parts by weight of OMNIRAD907 and 0.2 parts by weight of LE-303 were mixed. This mixture was diluted with an MIBK / cyclopentanone mixed solvent (weight ratio 70 / 30) so that the solid content concentration became 30% to prepare and formulate a coating liquid for forming a resin layer. An optical film 7 of Comparative Example 2 was obtained in the same manner as in Example 1, except that the coating liquid for forming a resin layer prepared above was used to form a coating film using a bar coater #10.

[0123] (Evaluation) Using the optical films obtained in the above Examples and Comparative Examples, the following evaluations were conducted. The evaluation methods are shown below. The results are shown in Table 1.

[0124] (1) Film thickness measurement Using a digital linear gauge (trade name "MODEL D-10HS", manufactured by Ozaki Manufacturing Co., Ltd.), the film thickness of the optical films of the Examples and Comparative Examples was measured at 5 points with respect to the width, and the average value of the 5 film thicknesses was taken as the total thickness. The film thickness of the light-transmissive base materials used in the Examples and Comparative Examples was measured by the same measurement method, and the average value of the 5 film thicknesses was taken as the base material thickness. The difference between the total thickness and the base material thickness was taken as the thickness of the resin layer.

[0125] (2) Moisture permeability measurement In accordance with JIS Z0208, the moisture permeability of the optical films of the Examples and Comparative Examples was measured at a temperature of 40°C and a relative humidity of 92%. The moisture permeability of the optical films of the Examples and Comparative Examples was measured under the same temperature and humidity conditions as 40°C and 92%, with the test temperature and humidity conditions being 60°C and 90% relative humidity, or 65°C and 90% relative humidity.

[0126] (3) Evaluation of color leakage of polarizers After storing the optical films of the examples and comparative examples at a temperature of 60°C and a relative humidity of 90% for 120 hours, when observing the film with the illuminance of the backlight set to 8000 candela in a dark room, if color bleeding such as unevenness or streaks was visually recognized, it was determined that there was color bleeding in the polarizer.

[0127] (4) Measurement of scratch resistance The optical films of the examples and comparative examples were cut out to a size of 5 cm × 15 cm, and on the surface of the resin layer, steel wool #0000 with a diameter of 2.5 cm and a contact area of 6.25×π cm 2 was brought into contact. A load of 100 gf (0.98 N) was applied to the steel wool, and the surface of the resin layer was rubbed 10 times back and forth at a moving speed of 100 mm / s with respect to the long side direction of the film. The presence or absence of scratches was visually determined in the central 5 cm × 5 cm portion of the film after the test under the environment of a fluorescent lamp and an LED light source.

[0128]

Table 1

[0129] The variations of the present invention are appended below. [Appendix 1] An optical film in which a resin layer is laminated on one surface of a light-transmissive substrate, wherein the resin layer is formed of a cured product of a curable composition containing at least one polymerizable compound selected from the group consisting of a monomer having a polymerizable functional group and an oligomer having a polymerizable functional group, The value obtained by dividing the value obtained by subtracting the water vapor permeability M 1 [g / m 2 ·24 h] of the optical film at a temperature of 40°C and a relative humidity of 92% from 1,000 by the thickness T [μm] of the resin layer ((1,000 - M 1 ) / T) is 100 or more, the optical film. [Appendix 2] An optical film in which a resin layer is laminated on one surface of a light-transmissive substrate, The resin layer is formed of a cured product of a curable composition containing at least one polymerizable compound selected from the group consisting of a monomer having a polymerizable functional group and an oligomer having a polymerizable functional group. The optical film has a moisture permeability M of 2,000 or less at a temperature of 60 ° C and a relative humidity of 90%. 2 [g / m 2 ·24h], and the value obtained by dividing the result by the thickness T [μm] of the resin layer ((2,000 - M 2 )) / T) is 200 or more. [Supplementary Note 3] The product [((1,000 - M 1 )) / T) × ((2,000 - M 2 )) / T)] of the value ((1,000 - M 1 )) / T) described in Supplementary Note 1 and the value ((2,000 - M 2 )) / T) described in Supplementary Note 2 is 20,000 or more. [Supplementary Note 4] The optical film according to any one of Supplementary Notes 1 to 3, wherein the surface of the resin layer is not scratched when a scratch resistance test is performed under the conditions of a load of 0.98 N, a moving speed of 100 mm / second, and 10 reciprocations using steel wool. [Supplementary Note 5] The optical film according to any one of Supplementary Notes 1 to 4, wherein the film thickness of the resin layer is 0.5 to 6 μm. [Supplementary Note 6] The optical film according to any one of Supplementary Notes 1 to 5, wherein the light-transmissive substrate contains at least one selected from the group consisting of a cellulose-based resin, a polyester-based resin, an acrylic-based resin, and a cyclic olefin-based polymer. [Supplementary Note 7] A polarizing plate in which a polarizer is disposed on the side opposite to the resin layer of the optical film according to any one of Supplementary Notes 1 to 6. [Supplementary Note 8] An image display device having the polarizing plate according to Supplementary Note 7. [Supplementary Note 9] The image display device according to Supplementary Note 8, wherein an adhesive layer and an optical member are laminated in this order on the resin layer. [Explanation of Reference Numerals]

[0130] 10 Optical film 1 Resin layer 2 Light-transmissive substrate 20 Polarizing plate 3 Polarizer 4 Light-transmissive substrate (optical compensation film) 5 Adhesive layer 30 Image display device 6 Image display panel 7 Adhesive layer 8 Optical member

Claims

1. An optical film having a resin layer laminated on one surface of a light-transmitting substrate, the material constituting the light-transmitting substrate is at least one selected from the group consisting of cellulose-based resins and polyester resins, the resin layer is formed of a cured product of a curable composition including at least one polymerizable compound selected from the group consisting of a monomer having a polymerizable functional group and an oligomer having a polymerizable functional group, the polymerizable compound includes a compound having a cyclic aliphatic hydrocarbon group and two or more polymerizable functional groups in the molecule, 1,000 to the moisture permeability M of the optical film under an environment of a temperature of 40° C. and a relative humidity of 92%. 1 [g / m 2 24h] is subtracted from the thickness T [μm] of the resin layer, and the result is divided by the thickness T [μm] of the resin layer ((1,000-M 1 ) / T) is 100 or more, An optical film having a thickness of 1 to 500 μm.

2. An optical film having a resin layer laminated on one surface of a light-transmitting substrate, the material constituting the light-transmitting substrate is at least one selected from the group consisting of cellulose-based resins and polyester resins, the resin layer is formed of a cured product of a curable composition including at least one polymerizable compound selected from the group consisting of a monomer having a polymerizable functional group and an oligomer having a polymerizable functional group, the polymerizable compound includes a compound having a cyclic aliphatic hydrocarbon group and two or more polymerizable functional groups in the molecule, 2,000 to the moisture permeability M of the optical film under an environment of a temperature of 60° C. and a relative humidity of 90%. 2 [g / m 2 24h] is subtracted from the thickness T [μm] of the resin layer, and the result is divided by the thickness T [μm] of the resin layer ((2,000-M 2 ) / T) is 200 or more, An optical film having a thickness of 1 to 500 μm.

3. The value ((1,000-M 1 ) / T) and the value ((2,000-M 2 ) / T) [((1,000-M 1 ) / T)×((2,000-M 2 3. The optical film of claim 1 , wherein the ratio of the refractive index to the refractive index of the optical fiber is 20,000 or more.

4. 4. The optical film according to claim 1, wherein the surface of the resin layer is not scratched when a scratch resistance test is performed using steel wool under conditions of a load of 0.98 N, a moving speed of 100 mm / sec, and 10 round trips.

5. The optical film according to any one of claims 1 to 4, wherein the resin layer has a thickness of 0.5 to 6 µm.

6. A polarizing plate comprising the optical film according to any one of claims 1 to 5, and a polarizer disposed on the opposite side of the resin layer.

7. An image display device comprising the polarizing plate according to claim 6 .

8. The image display device according to claim 7 , further comprising a pressure-sensitive adhesive layer and an optical member laminated in this order on the resin layer.

Images