JP7693348B2 - Optical Film - Google Patents

Description

The present invention relates to an optical film. In particular, the present invention relates to an optical film suitable for use as a polarizing plate protective film.

Image display devices (e.g., liquid crystal display devices, organic EL display devices, etc.) often have a polarizing plate arranged on at least one side of the display cell due to the image formation method. The role of the polarizing plate is to pass only light polarized in a certain direction, and the performance of the image display device is greatly influenced by the performance of the polarizing plate. Polarizing plates are generally composed of a polarizer made of a polyvinyl alcohol film or the like on which iodine or a dye has been adsorbed and oriented, and a transparent protective film (polarizing plate protective film) attached to at least one side of the polarizer (e.g., Patent Document 1).

JP 2000-338329 A

In recent years, the market for mobile applications such as smartphones and tablet terminals has expanded, and the need for thinner image display devices has increased. This has led to a demand for thinner components constituting polarizing plates, such as polarizing plate protective films. However, as the thickness of the polarizing plate protective film decreases, there is a problem in that the protective function for the polarizer decreases.

For example, when the polarizing plate protective film becomes thinner, its moisture permeability (moisture permeability) increases, and the polarizing performance of the polarizer is lost in a humid environment, which may result in a phenomenon known as "color loss."

In addition, when the polarizing plate protective film becomes thin, there is a problem that the surface hardness and scratch resistance decrease, the film becomes more susceptible to scratches during the manufacturing process, and the performance of the polarizing plate decreases, such as a decrease in low moisture permeability. Therefore, the optical film used in the polarizing plate protective film is also required to have excellent scratch resistance.

To improve the low moisture permeability of polarizing plate protective films, it is necessary to introduce a highly hydrophobic structure into the resin that constitutes the film. However, highly hydrophobic chemical structures are generally bulky and therefore tend to have a sparse structure, which can lead to problems such as reduced surface hardness and scratch resistance. In other words, there is a trade-off between low moisture permeability and scratch resistance, and it is generally difficult to achieve both.

The present invention was conceived in light of the above circumstances, and the object of the present invention is to provide an optical film suitable for use as a polarizing plate protective film, which is capable of achieving both low moisture permeability and excellent scratch resistance even when made thin.

That is, the first aspect of the present invention provides an optical film in which a resin layer is laminated on one surface of a light-transmitting substrate. The resin layer imparts excellent low moisture permeability to the optical film of the first aspect of the present invention. The resin layer also imparts excellent scratch resistance to the optical film of the first aspect of the present invention. Therefore, the optical film of the first aspect of the present invention having the resin layer in a laminate structure is suitable as a polarizing plate protective film.

In the optical film of the first aspect of the present invention, the resin layer is formed of a cured product of a curable composition containing a polymerizable compound A having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group, and a polymerizable compound B other than the polymerizable compound A. This configuration is suitable for imparting excellent low moisture permeability to the optical film of the first aspect of the present invention. It is also suitable for imparting excellent scratch resistance to the optical film of the first aspect of the present invention.

In the optical film of the first aspect of the present invention, the ratio of the polymerizable compound A to the polymerizable compound B (polymerizable compound A/polymerizable compound B) is 95/5 to 10/90. The cyclic aliphatic hydrocarbon group of the polymerizable compound A has a highly hydrophobic chemical structure, and can impart excellent low moisture permeability to the resin layer. However, since it is bulky, the structure tends to become sparse, and the surface hardness and scratch resistance tend to decrease. On the other hand, the polymerizable compound B is multifunctional, and can increase the scratch resistance of the resin layer by increasing the crosslinking density. Therefore, the optical film of the first aspect of the present invention, which includes the resin layer formed of a cured product of a curable composition containing the polymerizable compound A and the polymerizable compound B and having a ratio (polymerizable compound A/polymerizable compound B) of 95/5 to 10/90 in a laminate structure, can achieve both excellent low moisture permeability and scratch resistance.

The ratio of the polymerizable compound A to the polymerizable compound B (polymerizable compound A/polymerizable compound B) is preferably 10/90 or more, more preferably 15/85 or more, from the viewpoint of imparting excellent low moisture permeability to the resin layer, 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. On the other hand, from the viewpoint that the resin layer achieves both low moisture permeability and scratch resistance at a higher level, and from the viewpoint that moisture in the polarizing plate is appropriately released to the outside to prevent the occurrence of "color loss" of the polarizer, 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.

In the optical film according to the first aspect of the present invention, the polymerizable compound B is preferably a 5-10 functionality urethane (meth)acrylate. This configuration is preferable for increasing the crosslink density of the resin layer and improving scratch resistance.

In the optical film of the first aspect of the present invention, the thickness of the resin layer is preferably 0.5 to 5 μm. As described above, even if the resin layer is thin, it can provide the optical film of the first aspect of the present invention with excellent low moisture permeability and scratch resistance. From the viewpoint of making the polarizing plate thinner when the optical film of the first aspect of the present invention is used as a polarizing plate protective film, the thickness of the resin layer is preferably 4.5 μm or less, preferably 4 μm or less, and may be 3.2 μm or less or 3 μm or less. The lower limit of the thickness of the resin layer is preferably 1.0 μm or more, more preferably 1.8 μm or more, and may be 2 μm or more, from the viewpoint of achieving both low moisture permeability and scratch resistance at a higher level.

In the optical film according to the first aspect of the present invention, it is preferable that the light-transmitting substrate contains at least one selected from the group consisting of cellulose-based resins, polyester-based resins, acrylic-based resins, and cyclic olefin-based polymers. These resins can be suitably used as substrates for polarizing plate protective films.

A second aspect of the present invention provides a polarizing plate, comprising the optical film according to the first aspect of the present invention and a polarizer disposed on the opposite side to the resin layer.
Furthermore, a third aspect of the present invention provides an image display device having the polarizing plate according to the second aspect of the present invention. In the image display device according to the third aspect of the present invention, it is preferable that a pressure-sensitive adhesive layer and an optical member are laminated in this order on the resin layer.

The polarizing plate according to the second aspect of the present invention has excellent low moisture permeability and scratch resistance even though the resin layer is thin, because the optical film according to the first aspect of the present invention is used as a polarizing plate protective film. Therefore, the image display device according to the third aspect of the present invention, which has the polarizing plate according to the second aspect of the present invention, is thin, but is unlikely to suffer from color loss of the polarizing plate in a humid environment, and has excellent durability.

The polarizing plate obtained by using the optical film of the present invention as a polarizing plate protective film has excellent low moisture permeability and scratch resistance even when made thin, is less susceptible to discoloration of the polarizer, and has excellent durability.

FIG. 1 is a schematic diagram (cross-sectional view) showing one embodiment of the optical film of the present invention. FIG. 2 is a schematic diagram (cross-sectional view) showing one embodiment of a polarizing plate having the optical film of FIG. FIG. 3 is a schematic diagram (cross-sectional view) showing one embodiment of an image display device having the polarizing plate of FIG.

A first aspect of the present invention provides an optical film comprising a resin layer laminated on one surface of a light-transmitting substrate.
The optical film according to the first aspect of the present invention may be referred to herein as the "optical film of the present invention". The light-transmitting substrate and the resin layer constituting the optical film of the present invention may be referred to herein as the "light-transmitting substrate of the present invention" and the "resin layer of the present invention", respectively. The term "film" includes the meanings of "sheet" and "tape". That is, the optical film of the present invention may have a sheet-like or tape-like form.

A second aspect of the present invention provides a polarizing plate comprising a polarizer disposed on the opposite side of the optical film of the present invention from the resin layer. The polarizing plate of the second aspect of the present invention may be referred to as the "polarizing plate of the present invention" in this specification.
A third aspect of the present invention provides an image display device having the polarizing plate of the present invention. The image display device according to the third aspect of the present invention may be referred to as the "image display device of the present invention" in this specification.

The following describes an embodiment of the optical film of the present invention with reference to the drawings, but the present invention is not limited to this embodiment and is merely an example.

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

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

FIG. 3 is a schematic diagram (cross-sectional view) showing one embodiment of an image display device having the polarizing plate of FIG.
3, an image display panel 6 is laminated on the pressure-sensitive adhesive layer 5 of a polarizing plate 20. In this embodiment, a pressure-sensitive adhesive layer 7 and an optical member 8 are laminated on a resin layer 1 in this order.
Each component will be described below.

<Optical film>
The term "optical" in the optical film of the present invention means that it is used for optical purposes, and more specifically, it means that it is used for the manufacture of products (optical products) using optical members. Examples of optical products include image displays and input devices such as touch panels, and it can be suitably used for the manufacture of liquid crystal image displays and self-luminous image displays (for example, organic EL (electroluminescence) image displays and LED image displays). More specifically, it can be suitably used as a protective film for a polarizing plate constituting an image display device.

The optical film of the present invention is not particularly limited in its form as long as a resin layer is laminated on one side of a light-transmitting substrate. For example, the optical film of the present invention may have a resin layer on only one side, or may have a resin layer on both sides. In addition, when the optical film of the present invention has a resin layer 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 is provided by the resin layer of the present invention, and the other resin layer is 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.

In addition to the light-transmitting substrate of the present invention and the resin layer of the present invention, the optical film of the present invention may have other layers, such as substrates other than the light-transmitting substrate of the present invention, resin layers other than the resin layer of the present invention, intermediate layers, undercoat layers, antistatic layers, separators, surface protection films, etc., on the surface or between any layers, as long as the effects of the present invention are not impaired.

The moisture permeability M ¹ [g/m ² ·24h] of the optical film of the present invention in an environment of a temperature of 40° C. and a relative humidity of 92% is preferably 700 g/m ² ·24h or less. The moisture permeability M ¹ of 700 g/m ² ·24h or less is preferable in that the occurrence of “color loss” of the polarizer in a humid environment can be suppressed when the optical film of the present invention is used as a polarizing plate protective film. From the viewpoint of suppressing the occurrence of color loss of the polarizer at a higher level, the moisture permeability M ¹ is preferably 600 g/m ² ·24h or less, and may be 550 g/m ² ·24h or less. The lower limit of the moisture permeability ^M1 is not particularly limited, but from the viewpoint of allowing moisture in the polarizing plate to escape to the outside and preventing the occurrence of “color loss” in the polarizer, it is preferably 100 g/ ^m2 ·24 h or more, more preferably 200 g/ ^m2 ·24 h or more, and may be 300 g/ ^m2 ·24 h or more, 310 g/ ^m2 ·24 h or more, or 320 g/ ^m2 ·24 h or more.

The moisture permeability ^M2 [g/ ^m2 ·24h] of the optical film of the present invention in an environment of a temperature of 60°C and a relative humidity of 90% is preferably 1,500 g/ ^m2 ·24h or less. The moisture permeability ^M2 of 1,500 g/ ^m2 ·24h or less is preferable in that the occurrence of "color loss" of the polarizer in a humid environment can be suppressed when the optical film of the present invention is used as a polarizing plate protective film. From the viewpoint of suppressing the occurrence of color loss of the polarizer at a higher level, the moisture permeability ^M2 is preferably 1,400 g/ ^m2 ·24h or less, more preferably 1,300 g/ ^m2 ·24h or less, and may be 1,200 g/ ^m2 ·24h or less. The lower limit of the moisture permeability ^M2 is not particularly limited, but from the viewpoint of allowing moisture in the polarizing plate to escape to the outside and preventing the occurrence of “color loss” in the polarizer, it is preferably 300 g/ ^m2 ·24 h or more, more preferably 500 g/ ^m2 ·24 h or more, and may be 800 g/ ^m2 ·24 h or more.

The moisture permeability ^M3 [g/ ^m2 ·24h] of the optical film of the present invention in an environment of a temperature of 65°C and a relative humidity of 90% is preferably 2,000g/ ^m2 ·24h or less. The moisture permeability ^M3 of 2,000g/ ^m2 ·24h or less is preferable in that the occurrence of "color loss" of the polarizer can be suppressed in a humid environment when the optical film of the present invention is used as a polarizing plate protective film. From the viewpoint of suppressing the occurrence of color loss of the polarizer at a higher level, the moisture permeability ^M3 is preferably 1,800g/ ^m2 ·24h or less, more preferably 1,600g/ ^m2 ·24h or less, and may be 1,400g/ ^m2 ·24h or less. The lower limit of the moisture permeability ^M3 is not particularly limited, but from the viewpoint of allowing moisture in the polarizing plate to escape to the outside and preventing the occurrence of “color loss” in the polarizer, it is preferably 500 g/ ^m2 ·24 h or more, more preferably 750 g/ ^m2 ·24 h or more, and may be 1,000 g/ ^m2 ·24 h or more.

In the optical film of the present invention, the product (T×M 1 ) of the thickness T [μm] of the resin layer of the present invention and the moisture permeability M ¹ [g/m ² ·24h] of the optical film of the present invention under an environment of a temperature of 40° ^C. and a relative humidity of 92% is preferably 1,500 or less. The resin layer of the present invention imparts excellent low moisture permeability to the optical film of the present invention, and generally, the thicker the film thickness, the higher the moisture permeability, and the thinner the film thickness, the lower the moisture permeability, which is in an inversely proportional relationship. Therefore, the product (T×M ¹ ) of the thickness T [μm] of the resin layer of the present invention and the moisture permeability M ¹ can be an index of the moisture permeability possessed by the resin layer of the present invention itself, and it can be said that the lower the product, the better the low moisture permeability. Therefore, the optical film of the present invention having a laminated structure of the resin layer of the present invention having the above product (T×M ¹ ) of 1,500 or less is imparted with excellent low moisture permeability even when the resin layer of the present invention is thin, and has both a thin structure and excellent low moisture permeability.

The configuration in which the product (T×M ¹ ) is 1,500 or less is preferable in that, when the optical film of the present invention is used as a polarizing plate protective film, excellent low moisture permeability can be imparted even when the resin layer of the present invention is thin, and the occurrence of "color loss" of the polarizer in a humid environment can be suppressed. From the viewpoint of achieving both the suppression of color loss of the polarizer and the thinning of the resin layer of the present invention at a higher level, the product (T×M ¹ ) is preferably 1,400 or less, more preferably 1,300 or less, and may be 1,200 or less. The lower limit of the product (T×M ¹ ) is not particularly limited, but from the viewpoint of preventing the occurrence of "color loss" of the polarizer by releasing moisture in the polarizing plate to the outside, it is preferably 500 or more, more preferably 600 or more, and may be 700 or more.

In the optical film of the present invention, the product (T×M 2 ) of the thickness T [μm] of the resin layer of the present invention and the moisture permeability M ² [g/m ² ·24h] of ^{the optical film of the present invention under an environment of a temperature of 60° C. and a relative humidity of 90% is preferably 3,000 or less. The product (T×M 2 )} can also be an index of the moisture permeability of the resin layer of the present invention itself, like the product (T×M ¹ ), and it can be said that the lower the product, the better the low moisture permeability. Therefore, the optical film of the present invention having a laminated structure of the resin layer of the present invention having the product (T×M ² ) of 3,000 or less is given excellent low moisture permeability even if the resin layer of the present invention is thin, and is preferable because it has both a thin structure and excellent low moisture permeability.

The configuration in which the product (T×M ² ) is 3,000 or less is preferable in that when the optical film of the present invention is used as a polarizing plate protective film, even if the resin layer of the present invention is thin, the occurrence of "color bleeding" of the polarizer can be suppressed in a humid environment. From the viewpoint of achieving both the suppression of color bleeding of the polarizer and the thinning of the resin layer of the present invention at a higher level, the product (T×M ² ) is preferably 2,900 or less, more preferably 2,800 or less, and may be 2,700 or less. The lower limit of the product (T×M ² ) is not particularly limited, but from the viewpoint of releasing moisture in the polarizing plate to the outside and preventing the occurrence of "color bleeding" of the polarizer, it is preferably 500 or more, more preferably 1,000 or more, and may be 1,500 or more.

In the optical film of the present invention, the product ((T× ^M1 )×(T× ^M2 )) of the product (T× ^M1 ) and the product (T× ^M2 ) is preferably 4,500,000 or less. The product ((T× ^M1 )×(T× ^M2 )) can be an index of the moisture permeability of the resin layer of the present invention itself, like the products (T× ^M1 ) and (T× ^M2 ), and it can be said that the lower the product, the better the low moisture permeability. Therefore, the optical film of the present invention having a laminated structure of the resin layer of the present invention in which the product ((T× ^M1 )×(T× ^M2 )) is 4,500,000 or less, is given excellent low moisture permeability even when the resin layer of the present invention is thin, and is preferable because it has both thinness and excellent low moisture permeability.

The configuration in which the product ((T×M ¹ )×(T×M ² )) is 4,500,000 or less is preferable in that when the optical film of the present invention is used as a polarizing plate protective film, even if the resin layer of the present invention is thin, the occurrence of "color bleeding" of the polarizer can be suppressed in a humid environment. From the viewpoint of achieving both the suppression of color bleeding of the polarizer and the thinning of the resin layer of the present invention at a higher level, the product ((T×M ¹ )×(T×M ² )) is preferably 4,000,000 or less, and more preferably 3,500,000 or less. The lower limit of the product ((T×M ¹ )×(T×M ² )) is not particularly limited, but from the viewpoint of releasing moisture in the polarizing plate to the outside and preventing the occurrence of "color bleeding" of the polarizer, it is preferably 50,000 or more, more preferably 100,000 or more, and may be 150,000 or more.

In the optical film of the present invention, the product (T×M 3 ) of the thickness T [μm] of the resin layer of the present invention and the moisture permeability M ³ [g/m ² ·24 h] of the optical film of the present invention under an environment of a temperature of 65° C. and a relative humidity of 90% is preferably 4,000 or less. The product (T×M ³ ) can be an index of the moisture permeability of the resin layer of the present invention itself, like the products (T×M ¹ ) and (T×M ² ) ^, and it can be said that the lower the product, the better the low moisture permeability. Therefore, the optical film of the present invention having a laminated structure of the resin layer of the present invention having the product (T×M ³ ) of 4,000 or less is provided with excellent low moisture permeability even if the resin layer of the present invention is thin, and is preferable because it has both a thin structure and excellent low moisture permeability.

The configuration in which the product (T×M ³ ) is 4,000 or less is preferable in that when the optical film of the present invention is used as a polarizing plate protective film, even if the resin layer of the present invention is thin, the occurrence of "color bleeding" of the polarizer can be suppressed in a humid environment. From the viewpoint of achieving both the suppression of color bleeding of the polarizer and the thinning of the resin layer of the present invention at a higher level, the product (T×M ³ ) is preferably 3,800 or less, more preferably 3,600 or less, and may be 3,400 or less. The lower limit of the product (T×M ³ ) is not particularly limited, but from the viewpoint of releasing moisture in the polarizing plate to the outside and preventing the occurrence of "color bleeding" of the polarizer, it is preferably 1,000 or more, more preferably 1,500 or more, and may be 2,000 or more.

In the optical film of the present invention, the value obtained by subtracting the moisture 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 and dividing the value by the thickness T [μm] of the resin layer ((1,000-M ¹ )/T) is preferably 100 or more. The resin layer of the present invention imparts excellent low moisture permeability to the optical film of the present invention, and generally, the thicker the film thickness, the higher the moisture permeability, and the thinner the film thickness, the lower the moisture permeability. The above numerical value "1,000" is an approximate value of the moisture permeability of the light-transmitting substrate of the present invention itself (light-transmitting substrate having no resin layer) at a temperature of 40° C. and a relative humidity of 92%, and the value obtained by subtracting the moisture permeability M ¹ [g/m ² ·24 h] from 1,000 is an approximate value of the moisture permeability reduced by providing a resin layer on the light-transmitting substrate of the present invention. Therefore, the value ((1,000- ^M1 )/T) can be an index of the moisture permeability to be reduced per 1 μm of thickness of the resin layer of the present invention in an environment of a temperature of 40° C. and a relative humidity of 92%, and it can be said that the higher the value, the better the low moisture permeability. Therefore, an optical film having a laminate structure of a resin layer of the present invention having the above value ((1,000- ^M1 )/T) of 100 or more is endowed with excellent low moisture permeability even when the resin layer is thin, and thus combines both a thin film and excellent low moisture permeability.

The configuration in which the value ((1,000-M ¹ )/T) is 100 or more is preferable in that, when the optical film of the present invention is used as a polarizing plate protective film, excellent low moisture permeability can be imparted even when the resin layer 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 the suppression of color bleeding of the polarizer and the thinning of the resin layer of the present invention 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. The upper limit of the value ((1,000-M ¹ )/T) is not particularly limited, but from the viewpoint of allowing moisture in the polarizing plate to escape to the outside and preventing the occurrence of "color bleeding" of the polarizer, it is preferably 500 or less, more preferably 400 or less, and may be 300 or less.

In the optical film of the present invention, the value obtained by subtracting the moisture permeability ^M2 [g/ ^m2 ·24h] of the optical film at a temperature of 60°C and a relative humidity of 90% from 2,000 and dividing the value by the thickness T [μm] of the resin layer ((2,000- ^M2 )/T) is preferably at least 200. The above-mentioned numerical value "2,000" is an approximate value of the moisture permeability of the light-transmitting substrate of the present invention itself (light-transmitting substrate having no resin layer) at a temperature of 60°C and a relative humidity of 90%, and the value obtained by subtracting the moisture permeability ^M2 [g/ ^m2 ·24h] from 2,000 is an approximate value of the moisture permeability reduced by providing a resin layer on the light-transmitting substrate of the present invention. Therefore, the value ((2,000- ^M2 )/T) can be an index of the moisture permeability that is reduced per 1 μm of thickness of the resin layer of the present invention in an environment at a temperature of 60° C. and a relative humidity of 90%, and it can be said that the higher the value, the better the low moisture permeability. Therefore, an optical film having a laminate structure with a resin layer of the present invention having the above value ((2,000- ^M2 )/T) of 200 or more is endowed with excellent low moisture permeability even when the resin layer is thin, and thus combines both a thin film and excellent low moisture permeability.

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 present invention is used as a polarizing plate protective film, excellent low moisture permeability can be imparted even when the resin layer of the present invention is thin, and the occurrence of "bleeding" of the polarizer in a humid environment can be suppressed. From the viewpoint of achieving both suppression of the occurrence of bleed of the polarizer and thinning of the resin layer 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 of the value ((2,000-M ² )/T) is not particularly limited, but from the viewpoint of allowing moisture in the polarizing plate to escape to the outside and preventing the occurrence of "bleeding" of the polarizer, it is preferably 1,000 or less, more preferably 800 or less, and may be 500 or less.

In the optical film of the present invention, the product of the values ((1,000- ^M1 )/T) and ((2,000- ^M2 )/T), [((1,000- ^M1 )/T) x ((2,000- ^M2 )/T)], is preferably 20,000 or more. The product [((1,000- ^M1 )/T) x ((2,000- ^M2 )/T)], like the values ((1,000- ^M1 )/T) and ((2,000- ^M2 )/T), can be an index of the moisture permeability of the resin layer itself of the present invention, and it can be said that the higher the product, the better the low moisture permeability. Therefore, the optical film of the present invention having a laminate structure of the resin layer of the present invention in which the product [((1,000- ^M1 )/T) x ((2,000- ^M2 )/T)] is 20,000 or more is preferred because it is endowed with excellent low moisture permeability even when the resin layer of the present invention is thin, and thus combines both thinness and excellent low moisture permeability.

The configuration in which the product [((1,000- ^M1 )/T) x ((2,000- ^M2 )/T)] is 20,000 or more is preferable in that when the optical film of the present invention is used as a polarizing plate protective film, the occurrence of "color bleeding" of the polarizer in a humid environment can be suppressed even if the resin layer of the present invention is thin. From the viewpoint of achieving a higher level of both suppression of color bleeding of the polarizer and thinning of the resin layer of the present invention, the product [((1,000- ^M1 )/T) x ((2,000- ^M2 )/T)] is preferably 21,000 or more, and more preferably 22,000 or more. The upper limit of the above-mentioned [((1,000- ^M1 )/T) x ((2,000- ^M2 )/T)] is not particularly limited, but from the viewpoint of allowing moisture in the polarizing plate to escape to the outside and preventing the occurrence of "color loss" in the polarizer, it is preferably 200,000 or less, more preferably 150,000 or less, and may be 120,000 or less.

In the optical film of the present invention, the value obtained by subtracting the moisture permeability ^M3 [g/ ^m2 ·24h] of the optical film at a temperature of 65°C and a relative humidity of 90% from 2,700 and dividing the value by the thickness T [μm] of the resin layer ((2,700- ^M3 )/T) is preferably at least 250. The above-mentioned numerical value "2,700" is an approximate value of the moisture permeability of the light-transmitting substrate of the present invention itself (light-transmitting substrate having no resin layer) at a temperature of 65°C and a relative humidity of 90%, and the value obtained by subtracting the moisture permeability ^M3 [g/ ^m2 ·24h] from 2,700 is an approximate value of the moisture permeability reduced by providing a resin layer on the light-transmitting substrate of the present invention. Therefore, the value ((2,700- ^M3 )/T) can be an index of the moisture permeability that is reduced per 1 μm of thickness of the resin layer of the present invention in an environment at 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 moisture permeability. Therefore, an optical film having a laminate structure with a resin layer of the present invention having the above value ((2,700- ^M3 )/T) of 250 or more is endowed with excellent low moisture permeability even when the resin layer is thin, and thus combines both a thin film and excellent low moisture permeability.

The configuration in which the value ((2,700-M ³ )/T) is 250 or more is preferable in that, when the optical film of the present invention is used as a polarizing plate protective film, excellent low moisture permeability can be imparted even when the resin layer 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 the suppression of color bleeding of the polarizer and the thinning of the resin layer 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 of the value ((2,700-M ³ )/T) is not particularly limited, but from the viewpoint of allowing moisture in the polarizing plate to escape to the outside and preventing the occurrence of "color bleeding" of the polarizer, it is preferably 1,000 or less, more preferably 800 or less, and may be 600 or less.

The optical film of the present invention preferably has a moisture permeability [g/m ² ·24 h] of 20 or less change before and after the following scratch resistance test in an environment of a temperature of 40° C. and a relative humidity of 92%.
Scratch Resistance Test: The surface of the resin layer is reciprocated 10 times with steel wool under conditions of a load of 3.92 N and a moving speed of 100 mm/sec.
In general, the moisture permeability after the scratch resistance test tends to be higher than that before the test, but the amount of change in the case where the moisture permeability after the scratch resistance test is lower than that before the test is also included. Therefore, the amount of change is, for example, the absolute value of the moisture permeability after the scratch resistance test minus the moisture permeability before the test.

The resin layer of the present invention imparts excellent low moisture permeability to the optical film of the present invention, and generally, the thicker the film thickness, the higher the moisture permeability, and the thinner the film thickness, the lower the moisture permeability. The resin layer of the present invention also imparts excellent scratch resistance to the optical film of the present invention, and generally, the thicker the film thickness, the higher the scratch resistance, and the thinner the film thickness, the lower the scratch resistance. Therefore, the optical film of the present invention having the resin layer of the present invention in a laminated structure such that the rate of change is 20 or less is imparted with excellent low moisture permeability and scratch resistance even when the resin layer of the present invention is thin, and thus combines thinness with excellent low moisture permeability and durability.

The configuration in which the rate of change is 20 or less is preferable in that, when the optical film of the present invention is used as a polarizing plate protective film, even if the resin layer of the present invention is thin, the surface hardness and scratch resistance are less likely to decrease, and the decrease in low moisture permeability due to scratches can be prevented, and the occurrence of "color loss" of the polarizer can be suppressed. From the viewpoint of achieving both the suppression of color loss of the polarizer and the scratch resistance of the resin layer of the present invention at a higher level, the amount of change is preferably 18 or less, more preferably 15 or less, and may be 12 or less, or 10 or less. The lower limit of the amount of change is not particularly limited, and it is most preferable that it is 0, that is, there is no change, but from the viewpoint of suppressing the occurrence of "color loss" of the polarizer, it may be, for example, about 0.1 or more to 0.5 or more.

The moisture permeabilities M ¹ , M ² , and M ³ in the optical film of the present invention, and the product of the thickness T of the resin layer and the moisture permeability M ¹ , M ² , or M ³ , such as ((1,000-M ¹ )/T), ((2,000-M ² )/T), or ((2,700-M ³ )/T), their products, and the change in moisture permeability before and after a scratch resistance test can be measured specifically by a known method, for example, in accordance with JIS Z0208. The moisture permeabilities M ¹ , M ² , and M ³ in the optical film of the present invention, and the products of the resin layer thickness T and the moisture permeabilities M ¹ , M ² , or M ³ , such as ((1,000-M ¹ )/T), ((2,000-M ² )/T), and ((2,700-M ³ )/T), their products, and the change in moisture permeability before and after a scratch resistance test, can be adjusted by adjusting the type and thickness of the resin constituting the light-transmitting substrate of the present invention, the above-mentioned configuration of the resin layer of the present invention, etc.

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, and 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-transmitting substrate of the present invention, the type and thickness of the resin constituting the resin layer of the present invention, etc.

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, and 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-transmitting substrate of the present invention, the composition and thickness of the resin layer of the present invention, etc.

The thickness of the optical film of the present invention is not particularly limited, but taking into consideration factors such as thinness, strength, and workability such as ease of handling, the thickness is preferably in the range of 1 to 500 μm, more preferably in the range of 10 to 300 μm, and most preferably in the range of 20 to 200 μm.

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

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

The total light transmittance in the visible light wavelength region of the light-transmitting substrate of the present invention is not particularly limited, but is preferably 85% or more, and 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-transmitting substrate of the present invention can be adjusted by the type and thickness of the resin constituting the light-transmitting substrate of the present invention.

The thickness of the light-transmitting substrate of the present invention is not particularly limited, but taking into consideration aspects such as thinness, strength, ease of handling, and thinness, the thickness is preferably in the range of 1 to 500 μm, more preferably in the range of 10 to 300 μm, and most preferably in the range of 20 to 200 μm.

The refractive index of the light-transmitting substrate of the present invention is not particularly limited, but is, for example, in the range of 1.30 to 1.80, and preferably in the range of 1.40 to 1.70. In addition, the surface of the light-transmitting substrate of the present invention (the surface on which the resin layer is formed and/or the surface opposite thereto) may be appropriately subjected to a known and commonly used surface treatment, such as a physical treatment such as a corona discharge treatment or a plasma treatment, or a chemical treatment such as an undercoat treatment.

<Resin Layer>
The resin layer of the present invention is laminated on one side of the light-transmitting substrate of the present invention, and imparts excellent low moisture permeability to the optical film of the present invention. 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 of the present invention in a laminate structure can be suitably used as a polarizing plate protective film.

It is preferable that the resin layer of the present invention is not scratched when its surface is subjected to an abrasion resistance test using steel wool under the conditions of a load of 0.98 N, a moving speed of 100 mm/sec, and 10 round trips. In other words, since the optical film of the present invention is coated with the resin layer of the present invention, which has excellent abrasion resistance, it is difficult to scratch during the manufacturing process even if it is made thin, and when used as a polarizing plate protective film, a polarizing plate with excellent durability can be provided. The excellent abrasion resistance of the resin layer of the present invention can be imparted by adjusting the above composition and thickness constituting the resin layer.

The resin layer of the present invention is formed from a cured product of a curable composition containing a polymerizable compound A having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group, and a multifunctional polymerizable compound B other than the polymerizable compound A. The curable composition of the present invention containing the polymerizable compounds A and B may be referred to as the "curable composition of the present invention."

The cyclic aliphatic hydrocarbon group of the polymerizable compound A has a highly hydrophobic chemical structure, and can impart excellent low moisture permeability to the resin layer, but is bulky and therefore the structure is likely to become sparse, and the surface hardness and scratch resistance are likely to decrease. On the other hand, the polymerizable compound B is multifunctional, and can increase the scratch resistance of the resin layer by increasing the crosslinking density. Therefore, the optical film of the present invention, which includes in its laminate structure the resin layer of the present invention formed of a cured product of a curable composition containing the polymerizable compound A and the polymerizable compound B, and in which the ratio (polymerizable compound A/polymerizable compound B) is 95/5 to 10/90, can achieve both excellent low moisture permeability and scratch resistance. 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. The curable composition of the present invention may also contain one type of polymerizable compound B, or may contain two or more types of polymerizable compound B.

The ratio of the polymerizable compound A to the polymerizable compound B (polymerizable compound A/polymerizable compound B) is preferably 10/90 or more, more preferably 15/85 or more, from the viewpoint of imparting excellent low moisture permeability to the resin layer, 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. On the other hand, from the viewpoint that the resin layer achieves both low moisture permeability and scratch resistance at a higher level, and from the viewpoint that moisture in the polarizing plate is appropriately released to the outside to prevent the occurrence of "color loss" of the polarizer, 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.

As the unsaturated double bond group possessed by the polymerizable compound A, a (meth)acryloyl group, a vinyl group, a styryl group, an allyl group, etc. are preferred, and among these, a (meth)acryloyl group is preferred. Particularly preferred are the following compounds containing two or more (meth)acryloyl groups in one molecule.

The number of "unsaturated double bond groups" that the polymerizable compound A has in the molecule is not particularly limited as long as it is 1 or more, but it is preferable that the polymerizable compound A has 2 or more unsaturated double bond groups, more preferably 3 or more, and even more preferably 4 or more, in order to impart excellent low moisture permeability and scratch resistance to the optical film of the present invention. The upper limit of the number of "unsaturated double bond groups" that the polymerizable compound A has is not particularly limited, but may be 10 or less, 9 or less, or 8 or less.

The "alicyclic hydrocarbon group" contained in the molecule of 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. The alicyclic hydrocarbon group is particularly preferably a group derived from a polycyclic compound such as a bicyclic or tricyclic compound.

As the cyclic aliphatic hydrocarbon group (including a linking group), a group represented by any one of the following general formulas (I) to (V) is preferable, a group represented by the following general formula (I), (II), or (IV) is more preferable, and a group represented by the following general formula (I) is even more preferable.

In formula (I), L and L′ each independently represents a divalent or higher valent linking group, and n represents an integer of 1 to 3.

In formula (II), L and L′ each independently represent a divalent or higher valent linking group, and n represents an integer of 1 or 2.

In formula (III), L and L′ each independently represents a divalent or higher linking group, and n represents an integer of 1 or 2.

In 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.

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

Specific examples of cyclic aliphatic hydrocarbon groups include monovalent to trivalent groups derived from norbornane, tricyclodecane, tetracyclododecane, pentacyclopentadecane, adamantane, diamantane, etc.

The polymerizable compound A containing a group represented by any one of the above general formulas (I) to (V) as a cyclic aliphatic 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 alkylene group having 1 to 6 carbon atoms which may be substituted, an amide group which may be di-substituted at the N-position, a carbamoyl group which may be substituted at the N-position, an ester group, an oxycarbonyl group, an ether group, etc., and groups obtained by combining these.

The polymerizable compound A can be easily synthesized, for example, by a one- or two-stage reaction between a polyol such as a diol or triol having the above-mentioned cyclic aliphatic hydrocarbon group and a carboxylic acid, carboxylic acid derivative, epoxy derivative, isocyanate derivative, or the like of a compound having a (meth)acryloyl group, vinyl group, styryl group, allyl group, or the like. Preferably, it can be synthesized by reacting a polyol having the above-mentioned cyclic aliphatic hydrocarbon group with (meth)acrylic acid, (meth)acryloyl chloride, (meth)acrylic anhydride, (meth)acrylate, glycidyl (meth)acrylate, 1,1-bis(acryloxymethyl)ethyl isocyanate, or the like.

Preferred specific examples of the polymerizable compound A are shown below, but the present invention is not limited to these.

The content of polymerizable compound A in the curable composition of the present invention is not particularly limited, but from the viewpoint of imparting excellent low moisture permeability to the resin layer of the present invention, it is preferably 10% by weight or more, more preferably 15% by weight or more, 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, relative to 100% by weight of the non-volatile solids content of the curable composition of the present invention. On the other hand, from the viewpoint that the resin layer of the present invention achieves both low moisture permeability and scratch resistance at a higher level, 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.

The polymerizable functional group possessed by the polymerizable compound B is preferably an unsaturated double bond group such as a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group, and among these, a (meth)acryloyl group is preferred. Particularly preferred are the following compounds containing two or more (meth)acryloyl groups in one molecule.

In addition to the polymerizable compound B, a polyfunctional polymerizable compound other than the polymerizable compound A is used, that is, a compound having no cyclic aliphatic hydrocarbon group in the molecule and having two or more polymerizable functional groups. The polymerizable compound A tends to have low scratch resistance due to the three-dimensional structure of the cyclic aliphatic hydrocarbon group in the molecule. It is believed that the curable composition of the present invention contains the polymerizable compound B in addition to the polymerizable compound A, thereby increasing the crosslink density and improving the scratch resistance.

The number of "polymerizable functional groups" possessed by the polymerizable compound B is not particularly limited as long as it is 2 or more, but from the viewpoint of imparting excellent scratch resistance to the optical film of the present invention, it is preferable that the number is 3 or more, more preferably 4 or more, or 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 may be 30 or less, 25 or less, or 20 or less. In particular, the number of "polymerizable functional groups" is preferably 5 to 10, and more preferably 8 to 10.

Examples of the polymerizable compound B include a monomer having no cyclic aliphatic hydrocarbon group in the molecule and having two or more polymerizable functional groups (hereinafter, sometimes referred to as "polymerizable monomer B"), and an oligomer having no cyclic aliphatic hydrocarbon group in the molecule and having two or more polymerizable functional groups (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 being able to form a high crosslink density, it is preferable to contain at least a polymerizable oligomer B.

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, and propoxylated trimethylolpropane tri(meth)acrylate. 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.

The polymerizable oligomer B is a compound containing two or more repeating units and having a polymerizable functional group. That is, the polymerizable oligomer B is a polymer having a polymerizable functional group in the molecule. Examples of the polymerizable oligomer B include urethane (meth)acrylate in which two or more (meth)acryloyl groups are added as functional groups to a urethane skeleton, polyester (meth)acrylate in which two or more (meth)acryloyl groups are added as functional groups to a polyester skeleton, and epoxy (meth)acrylate in which two or more (meth)acryloyl groups are added as functional groups to an epoxy skeleton. From the viewpoint of being able to form a high crosslink density, it is preferable to contain at least a urethane (meth)acrylate, and in particular, a urethane (meth)acrylate with a functionality of 5 to 10 is preferable. The curable composition of the present invention may contain one type of polymerizable oligomer B, or may contain two or more types of polymerizable oligomer B.

The urethane (meth)acrylate can be obtained, for example, by reacting a polyol, an isocyanate, and a hydroxy (meth)acrylate.
As the polyol constituting the urethane (meth)acrylate, known polyols can be used without limitation, but from the viewpoint of improving the crosslink density, a polyol having 3 or more hydroxyl groups (preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more) is preferred, and examples of such polyols include trimethylolpropane, ethoxylated isocyanuric acid, pentaerythritol, dipentaerythritol, tripentaerythritol, tetrapentaerythritol, etc. These polyols may be used alone or in combination of two or more.

As the isocyanate that constitutes the urethane (meth)acrylate, a polyisocyanate composed of chain saturated hydrocarbons, cyclic saturated hydrocarbons, or 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-cyclohexylisocyanate), 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 examples include isophorone diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate. These polyisocyanates may be used alone or in combination of two or more.

Examples of hydroxy(meth)acrylates constituting urethane(meth)acrylates 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.

Examples of urethane (meth)acrylates include the Art Resin UN series manufactured by Negami Chemical Industries Co., Ltd., the NK Oligo U series manufactured by Shin-Nakamura Chemical Co., Ltd., and the Shiko UV series manufactured by Mitsubishi Chemical Corporation.

Polyester (meth)acrylates are obtained, for example, by reacting the terminal hydroxyl groups of polyester obtained by polymerizing polyol and polycarboxylic acid with (meth)acrylic acid. Specific examples of polyester (meth)acrylates include ARONIX M-6000, ARONIX M-7000, ARONIX M-8000, and ARONIX M-9000 manufactured by Toa Gosei Co., Ltd.

Epoxy (meth)acrylates can be obtained, for example, by reacting epoxy resins with (meth)acrylic acid. Specific examples of epoxy (meth)acrylates include Lipoxy SP and Lipoxy VR manufactured by Showa Polymer Co., Ltd., and the Epoxy Ester series manufactured by Kyoeisha Chemical Co., Ltd.

The weight average molecular weight of the polymerizable oligomer B is not particularly limited, but is preferably 400 or more, more preferably 500 or more, even more preferably 600 or more, and particularly preferably 700 or more, from the viewpoint of improving the scratch resistance of the resin layer of the present invention. In addition, the weight average molecular weight of the polymerizable oligomer B is preferably 10,000 or less, more preferably 7,000 or less, and even more preferably 5,000 or less, from the viewpoint of the coatability of the curable composition of the present invention. The weight average molecular weight of the polymerizable oligomer B can be determined, for example, by high performance liquid chromatography (HPLC). For example, the weight average molecular weight can be measured using an HPLC8020 manufactured by Tosoh Corporation as an apparatus, two TSKgelGMH-H (20) columns connected in series as columns, tetrahydrofuran as a solvent, and a flow rate of 0.5 mL/min.

The content of polymerizable compound B in the curable composition of the present invention is not particularly limited, but from the viewpoint of imparting excellent scratch resistance to the resin layer of the present invention, it is preferably 5% by weight or more, more preferably 10% by weight or more, and even more preferably 15% by weight or more, 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, relative to 100% by weight of the non-volatile solids content of the curable composition of the present invention. On the other hand, from the viewpoint of achieving a higher level of both low moisture permeability and scratch resistance 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.

The curable composition of the present invention preferably contains a polymerization initiator, and the polymerization initiator is preferably a photopolymerization initiator. Examples of photopolymerization initiators include benzophenone-based compounds such as benzil, benzophenone, benzoylbenzoic acid, and 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, and α-hydroxycyclohexylphenylketone; acetophenone-based compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin methyl ether. Benzoin alkyl ether compounds such as benzoin butyl ether and anisoin methyl ether; aromatic ketal compounds such as benzyl dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1_propanedione-2-(o-ethoxycarbonyl)oxime; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxides; acylphosphonates, etc. These polymerization initiators may be used alone or in combination of two or more.

The content of the photopolymerization initiator in the curable composition of the present invention is not particularly limited, but from the viewpoint of obtaining sufficient 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 even more preferably 0.2 parts by weight or more, relative to 100 parts by weight of the polymerizable compound (total of polymerizable compound A and polymerizable compound B). In addition, from the viewpoint of suppressing the inconvenience that the curable composition of the present invention is not sufficiently cured due to excessive radiation absorption by the photopolymerization initiator, the content of the photopolymerization initiator in the curable composition of the present invention is preferably 10 parts by weight or less, more preferably 8 parts by weight or less, relative to 100 parts by weight of the polymerizable compound (total of polymerizable compound A and polymerizable compound B).

Various leveling agents can be added to the curable composition of the present invention. As the leveling agent, for example, a fluorine-based or silicone-based leveling agent can be used for the purpose of preventing uneven coating (uniformity of the coating surface). When antifouling properties are required on the surface of the resin layer of the present invention, a leveling agent can be appropriately blended.
The amount of the leveling agent to be added is, for example, 5 parts by weight or less, preferably in the range of 0.01 to 5 parts by weight, based on 100 parts by weight of the polymerizable compounds (the total of the polymerizable compounds A and B).

The curable composition of the present invention may contain a solvent. As the solvent, various solvents may be used taking into consideration the solubility of the polymerizable compounds (polymerizable compound A and polymerizable compound B), drying properties during application, 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, 2-methoxyacetate, 2-ethoxyacetate, 2-ethoxyethyl acetate, 2-ethoxypropionate, 2-methoxyethanol, 2-propoxyethanol, 2-methoxypropionate, 2-methoxypropionate, 2-methoxypropionate, 2-methoxypropionate, 2-propoxy ... -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. can be used alone or in combination of two or more.

The curable composition of the present invention may further contain any suitable additives, such as plasticizers, surfactants, antioxidants, UV absorbers, thixotropic agents, and antistatic agents, as necessary, within the scope of not impairing the effects of the present invention.

The thickness of the resin layer of the present invention is preferably 0.5 to 5 μm. As described above, even if the resin layer of the present invention is thin, it can impart excellent low moisture permeability and scratch resistance to the optical film of the present invention. From the viewpoint of making the polarizing plate thinner when the optical film of the present invention is used as a polarizing plate protective film, the thickness of the resin layer is preferably 4.5 μm or less, preferably 4 μm or less, and may be 3.2 μm or less or 3 μm or less. From the viewpoint of achieving both low moisture permeability and scratch resistance at a higher level, the lower limit of the thickness of the resin layer of the present invention is preferably 1.0 μm or more, more preferably 1.8 μm or more, and may be 2 μm or more. The resin layer of the present invention may be one layer or multiple layers. When the resin layer of the present invention is composed of multiple layers, the thickness of the resin layer of the present invention is the sum of the layers constituting the multiple layers.

The resin layer of the present invention can be formed by mixing polymerizable compound A and polymerizable compound B with, as necessary, a polymerizable compound other than polymerizable compound A and polymerizable compound B, a photopolymerization initiator, a leveling agent, a solvent, other additives, etc. to prepare a coating liquid (curable composition of the present invention), applying the coating liquid to one side of a light-transmitting substrate, drying, and curing the coating film.

The solids concentration of the coating liquid is preferably 1% to 70% by weight, more preferably 2% to 50% by weight, and even more preferably 5% to 40% by weight.

Examples of methods for applying the coating liquid include dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, die coating, extrusion coating, and bar coating.

The method for curing the coating film is appropriately selected depending on the type of the curable composition. When the curable composition is photocurable, it can be cured by irradiating it with 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/ ^cm2 or more, preferably light with an exposure amount of 200 mJ/ ^cm2 to 1000 mJ/ ^cm2 can be used. Heating may also be performed during the photocuring treatment.
Examples of light include ionizing radiation such as α-rays, β-rays, γ-rays, neutron beams, and electron beams, and ultraviolet rays, among which ultraviolet rays are particularly preferred. The irradiation time, irradiation method, and the like are not particularly limited as long as they can activate the photopolymerization initiator and cause a reaction of the polymerizable compound.

<Polarizing Plate>
The polarizing plate of the present invention has a laminated structure in which a polarizer is disposed on the opposite side of 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 opposite side of 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 scratch resistance even if the resin layer 1 is thin, and quality deterioration such as discoloration of the polarizer 3 is unlikely to occur. In this embodiment, a second light-transmitting substrate 4 and a pressure-sensitive adhesive layer 5 are further laminated in this order on the opposite side of the polarizer 3 to the optical film 10.

The polarizer 3 is an element that transmits only light polarized in a certain direction, and any known material can be used without limitation, for example, a polyvinyl alcohol-based polarizing film. The polyvinyl alcohol-based polarizing film may be a polyvinyl alcohol-based film dyed with iodine or a dichroic dye.

The polyvinyl alcohol polarizing film may be a polyvinyl alcohol film that has been uniaxially stretched and then dyed with iodine or a dichroic dye (preferably further treated for durability with a boron compound); or a polyvinyl alcohol film that has been dyed with iodine or a dichroic dye and then uniaxially stretched (preferably further treated for durability with a boron compound). The absorption axis of the polarizer is parallel to the stretching direction of the film.

The thickness of the polarizer 3 is preferably 5 to 25 μm, and from the viewpoint of making the polarizing plate 20 thinner, it is more preferably 10 to 15 μm.

The second light-transmitting substrate 4 protects the side of the polarizer 3 opposite to the optical film 10 (polarizing plate protective film), and can be made of glass or plastic film similar to the light-transmitting substrate of the present invention. Cellulose-based resin, cyclic olefin polymer (COP), polycarbonate-based resin are preferred, and cyclic olefin polymer (COP) and polycarbonate-based resin are more preferred. The light-transmitting substrate 4 may be made of the same material as the light-transmitting substrate 2, or may be made of a different material. The light-transmitting substrate 4 may be a substrate having a resin layer 1 laminated thereon, or may not have a resin layer 1. The light-transmitting substrate 4 may be made of a single layer, or may have a laminate structure of two or more layers, the same or different.

The light-transmitting substrate 4 is also preferably an optical compensation film (retardation film) having an optical compensation layer including an optically anisotropic layer. The optical compensation film can improve the viewing angle characteristics of the liquid crystal display screen, for example. Any known optical compensation film can be used without limitation, and for example, a retardation film described in JP-A-2014-194484 may be used.

The thickness of the light-transmitting substrate 4 is preferably 5 to 25 μm, and from the viewpoint of making the polarizing plate 20 thinner, it is more preferably 10 to 15 μm.

The adhesive layer 5 is formed of any suitable adhesive. Examples of materials constituting the adhesive layer 5 include materials having a base polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based polymer, a rubber-based polymer, an isocyanate-based polymer, a polyvinyl alcohol-based polymer, a gelatin-based polymer, a vinyl-based polymer, a latex-based polymer, or a water-based polyester. Among these, materials having an acrylic polymer and/or a rubber-based polymer as a base polymer are preferred from the viewpoint of low moisture permeability. The adhesive layer 5 may contain a single base polymer or may contain two or more types of base polymers.

The thickness of the adhesive layer 5 is preferably 5 to 25 μm, and from the viewpoint of making the polarizing plate 20 thinner, it is more preferably 10 to 20 μm.

The polarizing plate 20 can be obtained by bonding the polarizer 1 and the optical film 10 together via an adhesive. The polarizer 1 and the light-transmitting substrate 4 can also be bonded together via an adhesive. The adhesive used for bonding may be a fully saponified polyvinyl alcohol aqueous solution (water glue), or an active energy ray-curable adhesive.

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

The polarizing plate 20, the optical film 10, the polarizing plate 3, the light-transmitting substrate 4, and the adhesive layer 5 may have layers (e.g., a surface protection film, a separator, etc.) on the surface or between any of the 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.

The thickness of the polarizing plate 20 (total thickness including the light-transmitting substrate 4 and the adhesive layer 5) is preferably 50 to 100 μm, and from the viewpoint of making the polarizing plate 20 thinner, it is more preferably 60 to 75 μm.

<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 a laminated structure, even if the resin layer 1 is thin, it has excellent low moisture permeability and scratch resistance, and is unlikely to suffer from quality deterioration such as discoloration of the polarizer 3. Therefore, even if the image display device of the present invention is thin, discoloration of the polarizing plate is unlikely to occur in a humid environment, and it has excellent durability.
3, an image display device 30 has an image display panel 6 laminated on an adhesive layer 5 of a polarizing plate 20. In this embodiment, an adhesive layer 7 and an optical member 8 are laminated on a resin layer 1 in this order.

The image display panel 6 is not particularly limited, but examples thereof include a liquid crystal image display panel, a self-luminous image display panel (e.g., an organic EL (electroluminescence) image display panel, an LED image display panel), etc.

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

The adhesive layer 7 may be made of a material containing a base polymer similar to those exemplified for the adhesive layer 5. In particular, from the viewpoint of low moisture permeability, a material containing an acrylic polymer and/or a rubber polymer as the base polymer is preferred. The adhesive layer 7 may contain a single base polymer or may contain two or more types of base polymers. The adhesive layer 7 may be made of the same material as the adhesive layer 5, or may be made of a different material.

The optical member 8 can be made of glass or plastic film similar to the light-transmitting substrate of the present invention, and is preferably made of acrylic resin, polyester resin, or cyclic olefin polymer (COP), and particularly preferably polyester resin. When the optical member 8 is located on the outermost surface of the viewing side of the image display device 30, it functions as a cover member.

The image display device 30 may have optical members other than the optical film 10, the polarizing plate 3, the light-transmitting substrate 4, the adhesive layer 5, the image display panel 6, the adhesive layer 7, and the optical member 8 on the surface or between any layers. The optical members are not particularly limited, but examples thereof include polarizing plates other than the polarizing plate 3, retardation plates, anti-reflection films, viewing angle adjustment films, and optical compensation films. The optical members 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 the input device.

The image display device 30 can be manufactured by laminating together an image display panel 6, a polarizing plate 20, and an optical film in which an optical member 8 and a pressure-sensitive adhesive layer 7 are laminated, and specifically, lamination can be performed under heat and/or pressure. After lamination under heat and/or pressure, active energy rays may be irradiated to perform curing. Irradiation of active energy rays can be performed in the same manner as in the formation of the resin layer of the present invention.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1
(Preparation of Coating Solution for Forming Resin Layer)
As the resin contained in the resin layer, 90 parts by weight (solid content equivalent) of ultraviolet-curable acrylate resin (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-DCP", solid content 100%) and 10 parts by weight (solid content equivalent) of ultraviolet-curable acrylate resin (manufactured by Mitsubishi Chemical Co., Ltd., product name "UV-1700TL", solid content 80%) were prepared. 5 parts by weight of photopolymerization initiator (manufactured by BASF, product name "OMNIRAD907") and 0.2 parts by weight of leveling agent (manufactured by Kyoeisha Chemical Co., Ltd., product name "LE-303", solid content 40%) were mixed per 100 parts by weight of the resin solid content of the resin. This mixture was diluted with a MIBK/cyclopentanone mixed solvent (weight ratio 60/40) so that the solid content concentration was 30%, to prepare a coating liquid for forming a resin layer.

(Preparation of Optical Films)
A transparent plastic film substrate (TAC, manufactured by Fujifilm Corporation, product name "TJ25UL") was prepared as a light-transmitting substrate. The resin layer-forming coating liquid prepared above was used to form a coating film on one side of the transparent plastic film substrate using a bar coater #7. The transparent plastic film substrate on which the coating film was formed was then transported to a drying process. In the drying process, the coating film was dried by heating at 60°C for 1 minute. Thereafter, the coating film was irradiated with ultraviolet light with an integrated light amount of 220 mJ/ ^cm2 from a high-pressure mercury lamp to cure the coating film and form a resin layer with a thickness of 2.5 μm, thereby obtaining an optical film 1 of Example 1.
Details of the resin used in Example 1 are as follows:
A-DCP: Tricyclodecane dimethanol dimethacrylate UV-1700TL: 10-functional urethane acrylate

Example 2
An optical film 2 of Example 2 was obtained in the same manner as in Example 1, except that 70 parts by weight (solid content equivalent) of A-DCP and 30 parts by weight (solid content equivalent) of UV-1700TL were blended as the resin contained in the resin layer.

Example 3
An optical film 3 of Example 3 was obtained in the same manner as in Example 1, except that 50 parts by weight (solid content equivalent) of A-DCP and 50 parts by weight (solid content equivalent) of UV-1700TL were blended as the resin contained in the resin layer.

Comparative Example 1
An optical film 4 of Comparative Example 1 was obtained in the same manner as in Example 1, except that 100 parts by weight (solid content equivalent) of A-DCP was blended as the resin contained in the resin layer.

Comparative Example 2
An optical film 5 of Comparative Example 2 was obtained in the same manner as in Example 1, except that 100 parts by weight (solid content equivalent) of UV-1700TL was blended as the resin contained in the resin layer.

(evaluation)
The optical films obtained in the above Examples and Comparative Examples were evaluated as follows. The evaluation methods are shown below. The results are shown in Table 1.

(1) Film Thickness Measurement The film thickness of the optical films of the Examples and Comparative Examples was measured at five points across the width using a digital linear gauge (product name "MODEL D-10HS", manufactured by Ozaki Manufacturing Co., Ltd.), and the average value of the film thicknesses at the five points was taken as the total thickness. The film thickness of the light-transmitting substrate used in the Examples and Comparative Examples was measured using a similar measurement method, and the average value of the film thicknesses at the five points was taken as the substrate thickness. The difference between the total thickness and the substrate thickness was taken as the thickness of the resin layer.

(2) Moisture Permeability Measurement The moisture permeability of the optical films of the examples and comparative examples was measured at 40° C. and a relative humidity of 92% in accordance with JIS Z0208.

(3) Evaluation of Polarizer Color Loss The optical films of the Examples and Comparative Examples were stored for 120 hours under an environment of 60°C and 90%, and then the films were observed in a dark room with the backlight illuminance set to 8,000 candela. If color loss such as unevenness or streaks was visually observed in the films, it was determined that color loss of the polarizer had occurred.

(4) Measurement of Scratch Resistance The optical films of the Examples and Comparative Examples were cut into pieces measuring 5 cm x 15 cm, and #0000 steel wool was brought into contact with the surface of the resin layer at a diameter of 2.5 cm and a contact area of 6.25 x π ^cm2 . A load of 100 gf (0.98 N) was applied to the steel wool, and the resin layer surface was rubbed back and forth 10 times in the long side direction of the film at a moving speed of 100 mm/s.
After the test under an environment of a fluorescent light and an LED light source, the presence or absence of scratches was visually determined in a central 5 cm x 5 cm area of the film.

(5) Moisture Permeability Measurement The temperature and humidity conditions for the test were set to a temperature of 60° C. and a relative humidity of 90%, or a temperature of 65° C. and a relative humidity of 90%, and the moisture permeability of the optical films of Examples 2 and 3 was measured in the same manner as for the temperature and humidity conditions of 40° C. and 92%.
the product (1) of the thickness [μm] of the resin layer and the moisture permeability [g/ ^m2 ·24h] of the optical film at a temperature of 40°C and a relative humidity of 92%, the product (2) of the thickness [μm] of the resin layer and the moisture permeability [g/ ^m2 ·24h] of the optical film at a temperature of 60°C and a relative humidity of 90%, the product (3) of the thickness [μm] of the resin layer and the moisture permeability [g/m2·24h] of the optical film at a temperature of 65°C and a relative humidity of 90%, the product (1) and the product (2) ((1) x (2)), 1,000 minus the moisture permeability [g/ ^m2 ·24h] of the optical film at a temperature of 40°C and a relative humidity of 92%, divided by the thickness [μm] of the resin layer, the moisture permeability [g/ ^m2 ·24h] of the optical film at a temperature of 60°C and a relative humidity of 90%, the product (4) of 2,000 minus the moisture permeability [g/m2·24h] of the optical film at a temperature of 60°C and a relative humidity of 90%, The moisture permeability [g/m2· ^24h ] of the optical film at a temperature of 65°C and a relative humidity of 90% is subtracted from 2,700 and divided by the thickness of the resin layer [μm] to obtain (5); the moisture permeability [g/ ^m2 ·24h] of the optical film at a temperature of 65°C and a relative humidity of 90% is subtracted from 2,700 and divided by the thickness of the resin layer [μm] to obtain (6); and the product ((4) x (5)) of values (4) and (5) is shown in Table 2.

(6) Moisture permeability measurement after scratch resistance test The optical films of Examples 2 and 3 were cut into a size of 5 cm x 15 cm, and #0000 steel wool was brought into contact with the surface of the resin layer so that the diameter was 2.5 cm and the contact area was 6.25 x π cm ^2. A load of 400 gf (3.92 N) was applied to the steel wool, which was rubbed back and forth across the surface of the resin layer 10 times in the long side direction of the film at a moving speed of 100 mm/s, and then the moisture permeability was measured at a temperature of 40°C and a relative humidity of 92% in the same manner as above.
The change in moisture permeability after the scratch resistance test was 9 g/m ² ·24 h for Example 2 and 1 g/m ² ·24 h for Example 3.

Variations of the present invention are listed below.
[Appendix 1] An optical film having a resin layer laminated on one surface of a light-transmitting substrate,
the resin layer is formed of a cured product of a curable composition including a polymerizable compound A having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group, and a polyfunctional polymerizable compound B other than the polymerizable compound A;
The ratio of the polymerizable compound A to the polymerizable compound B (polymerizable compound A/polymerizable compound B) is 95/5 to 10/90.
[Appendix 2] The optical film according to appendix 1, wherein the polymerizable compound B is a 5-10 functional urethane (meth)acrylate.
[Appendix 3] The optical film according to appendix 1 or 2, wherein the resin layer has a thickness of 0.5 to 5 μm.
[Appendix 4] The optical film according to any one of Appendices 1 to 3, wherein the light-transmitting substrate comprises 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.
[Appendix 5] A polarizing plate comprising the optical film according to any one of Appendices 1 to 4, and a polarizer disposed on the opposite side of the resin layer.
[Appendix 6] An image display device having the polarizing plate according to appendix 5.
[Appendix 7] The image display device according to appendix 6, wherein a pressure-sensitive adhesive layer and an optical member are laminated in this order on the resin layer.

10 Optical film 1 Resin layer 2 Light-transmitting substrate 20 Polarizing plate 3 Polarizer 4 Light-transmitting substrate (optical compensation film)
5 Pressure-sensitive adhesive layer 30 Image display device 6 Image display panel 7 Pressure-sensitive adhesive layer 8 Optical member

Claims (6)

An optical film having a resin layer laminated on one surface of a light-transmitting substrate,
the resin layer is formed of a cured product of a curable composition including a polymerizable compound A having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group, and a polyfunctional polymerizable compound B other than the polymerizable compound A;
the polymerizable compound B is a 5-10 functional urethane ( meth)acrylate which is a reaction product of a polyol, an isocyanate, and a hydroxy (meth)acrylate , the polyol being at least one selected from the group consisting of trimethylolpropane, ethoxylated isocyanuric acid, pentaerythritol, dipentaerythritol, tripentaerythritol, and tetraerythritol;
A polarizing plate protective film, wherein the ratio of the polymerizable compound A to the polymerizable compound B (polymerizable compound A/polymerizable compound B) is 95/5 to 65/35. 2. The polarizing plate protective film according to claim 1, wherein the resin layer has a thickness of 0.5 to 5 μm. 3. The polarizing plate protective film according to claim 1, wherein the light-transmitting substrate comprises 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. A polarizing plate comprising the polarizing plate protective film according to any one of claims 1 to 3, and a polarizer disposed on the opposite side of the resin layer. An image display device having the polarizing plate according to claim 4. The image display device according to claim 5 , further comprising a pressure-sensitive adhesive layer and an optical member laminated in this order on the resin layer.

Images