TW201841733A - Optical film and image display device - Google Patents

Abstract

One embodiment of the present invention provides a foldable optical film 10 which is used in an image display device, and which is provided with: a resin substrate 11 that is formed from one or more resins selected from the group consisting of polyimide resins, polyamide-imide resins, polyamide resins and polyester resins; a functional layer 12 that is arranged on a first surface 11A side of the resin substrate 11; and a first optical adjustment layer 13 that is arranged between the resin substrate 11 and the functional layer 12 so as to be adjacent to the functional layer 12.

Description

 Optical film and image display device  

[Reference to relevant application]

This case has the priority of Japan's special wish 2017-64583 (application date: March 29, 2017) and Japan's special offer 2018-35426 (application date: February 28, 2018) as the previous Japanese application. The disclosure of the content is generally referred to as part of this specification by reference.

The present invention relates to an optical film and an image display device.

Since the past, image display devices such as smart phones or tablet terminals have been known, and development of collapsible image display devices is currently underway. Generally, a smart phone or a tablet terminal is covered with a cover glass. The glass generally has excellent hardness but cannot be bent. Therefore, when the cover glass is used for an image display device, if it is to be folded, the crack is high. Therefore, in the case of the foldable image display device, it has been studied to use a foldable optical film having a flexible resin substrate and a hard coat layer instead of the cover glass (for example, see JP-A-2016-125063).

In such a foldable optical film, generally, the resin constituting the bendable resin substrate has a high refractive index, and thus the refractive index difference between the resin substrate and the hard coat layer becomes large. Therefore, due to the difference in refractive index between the resin substrate and the hard coat layer, iridescence-like unevenness, i.e., interference fringes, may occur.

In order to suppress the occurrence of interference fringes, there is a method of increasing the film thickness of the hard coat layer. However, if the film thickness of the hard coat layer is increased, there is a problem that the hard coat layer is broken at the time of folding. Therefore, the current situation is that an optical film that is foldable and does not easily generate interference fringes cannot be obtained.

On the other hand, in the case of such an optical film, dust may be attached or damaged during assembly in the image display device, and the yield may be lowered. Substrates for collapsible optical films are preferred because of their high price. In this case, there is a case where the protective film is attached to both surfaces of the optical film. However, when the protective film is peeled off from the optical film, both surfaces of the optical film are charged, so that the yield cannot be improved.

The present invention has been accomplished in order to solve the above problems. That is, an object of the present invention is to provide a foldable optical film which is less likely to cause interference fringes, and an image display device including the same. Further, it is an object of the present invention to provide a foldable optical film capable of improving the assembly procedure of an image display device, and an image display device including the same.

According to an aspect of the present invention, there is provided an optical film which is used for an image display device and which is foldable, and comprises: a resin substrate selected from the group consisting of polyimide-based resins and polyamidiamines. a resin composed of one or more of a group consisting of a resin, a polyamide resin, and a polyester resin; a functional layer provided on the first surface side of the resin substrate; and a first optical adjustment layer; It is provided between the resin substrate and the functional layer, and is adjacent to the functional layer.

In the above optical film, the refractive index of the first optical adjustment layer may be lower than the refractive index of the resin substrate and higher than the refractive index of the functional layer.

In the above optical film, the film thickness of the first optical adjustment layer may be 30 nm or more and 200 nm or less.

Further, the optical film may further include a second optical adjustment layer provided between the resin substrate and the first optical adjustment layer and adjacent to the resin substrate.

In the above optical film, the film thickness of the second optical adjustment layer may be 30 nm or more and 200 nm or less.

Further, the optical film may further include a resin layer provided on the second surface side of the resin substrate opposite to the first surface side and having a thickness of 50 μm or more and 300 μm or less. The shear storage modulus G' at 25 ° C and in the frequency region of 500 Hz or more and 1000 Hz or less exceeds 200 MPa and is 1200 MPa or less, and the optical film is cut at a frequency region of 25 ° C and above 500 Hz and below 1000 Hz. The loss modulus G" is 3 MPa or more and 150 MPa or less.

Further, the optical film may further include a third optical adjustment layer provided on a second surface of the resin substrate opposite to the first surface.

Further, the optical film may further include a third optical adjustment layer provided between the resin substrate and the resin layer and adjacent to the resin substrate.

In the above optical film, the optical film may have a yellow index of 15 or less.

In the above-mentioned optical film, it is preferable that the film is folded over 180 times in a case where the test layer is folded by 180° so that the functional layer is inside and the interval between the opposite sides of the optical film is 10 mm. fracture.

In the above-mentioned optical film, it is preferable that the film is folded over 180 times in a case where the test layer is folded over 180 times so that the functional layer is outside and the interval between the opposite sides of the optical film is 30 mm. fracture.

According to another aspect of the present invention, an optical film is provided for use in an image display device and is foldable, and includes: a light transmissive substrate; and a first antistatic layer disposed on the light transmissive substrate The first surface side and the second antistatic layer are provided on the second surface side of the light transmissive substrate opposite to the first surface.

In the above optical film, the optical film may have a yellow index of 15 or less.

In the above optical film, the first antistatic layer may be an antistatic hard coat layer.

Further, the optical film may further include an optical adjustment layer provided on a side opposite to the light-transmitting substrate side of the first antistatic layer.

Further, the optical film may further include a hard coat layer provided between the light-transmitting substrate and the first antistatic layer.

In the above optical film, the saturation voltage of the front surface of the optical film may be applied when a voltage of 10 kV is applied at a distance of 50 mm from the front surface of the optical film at 23 ° C and a relative humidity of 50%. The absolute value exceeds 0kV.

In the above optical film, it is preferable that cracking or cracking does not occur in a case where the test is performed by repeating the test in which the distance between the opposite sides of the optical film is set to 3 mm by 100,000 times.

In the above optical film, the light-transmitting substrate may be a substrate composed of a polyimide-based resin, a polyamide resin, or a mixture thereof.

According to another aspect of the present invention, a foldable video display device includes: a display element; and the optical film disposed on an observer side of the display element.

In the above image display device, the display element may be an organic light emitting diode element.

According to an aspect of the present invention, a foldable optical film which is less prone to interference fringes can be provided. Moreover, according to another aspect of the present invention, a foldable optical film capable of improving the yield of an assembly step of an image display device can be provided. Furthermore, according to another aspect of the present invention, an image display apparatus including such an optical film can be provided.

10, 30, 40, 50, 60, 90, 100‧ ‧ optical film

10A, 12A, 30A, 40A, 50A, 60A, 90A, 92A, 100A, 104A‧‧‧ positive

11‧‧‧Resin substrate

11A‧‧‧1st

11B‧‧‧2nd

12‧‧‧ functional layer

13‧‧‧1st optical adjustment layer

14‧‧‧2nd optical adjustment layer

15‧‧‧3rd optical adjustment layer

80,110‧‧‧Image display device

83‧‧‧Display components

92, 103‧‧‧1st antistatic layer

93, 105‧‧‧2nd antistatic layer

102‧‧‧hard coating

104‧‧‧Optical adjustment layer

Fig. 1 is a schematic configuration diagram of an optical film according to a first embodiment.

2(A) to 2(C) are diagrams schematically showing the state of the continuous folding test.

3(A) and 3(B) are diagrams schematically showing the state of the folding rest test.

Fig. 4 is a schematic configuration diagram of another optical film of the first embodiment.

Fig. 5 is a schematic configuration diagram of another optical film of the first embodiment.

Fig. 6 is a schematic configuration diagram of another optical film of the first embodiment.

Fig. 7 is a schematic configuration diagram of another optical film of the first embodiment.

Fig. 8 is a schematic configuration diagram of a solid shearing jig used for measuring the shear storage modulus G' and the shear loss modulus G".

Fig. 9 is a schematic configuration diagram of a video display device according to the first embodiment.

Fig. 10 is a schematic configuration diagram of an optical film of a second embodiment.

Fig. 11 is a schematic configuration diagram of another optical film of the second embodiment.

Fig. 12 is a schematic configuration diagram of a video display device according to a second embodiment.

[First Embodiment]

Hereinafter, an optical film and a video display device according to a first embodiment of the present invention will be described with reference to the drawings. In this specification, terms such as "film" and "slice" are not distinguished from each other only by the difference in the title. Thus, for example, "film" is used in the sense that it also includes a member, also referred to as a sheet. Fig. 1 is a schematic configuration diagram of an optical film of the present embodiment, and Figs. 2(A) to 2(C) are diagrams schematically showing a state of a continuous folding test, and Figs. 3(A) and 3(B) are diagrams. A diagram showing the state of the folding rest test is schematically shown. 4 to 7 are schematic configuration diagrams of other optical films of the embodiment, and Fig. 8 is a schematic configuration diagram of a solid shearing jig used for measuring the shear storage modulus G' and the shear loss modulus G".

<<<Optical film>>>

The optical film 10 shown in Fig. 1 is used for an image display device and is foldable.

The optical film 10 includes a resin substrate 11 and a functional layer 12 which is provided on the first surface 11A side which is one surface of the resin substrate 11 and a first optical adjustment layer 13 (hereinafter, simply referred to as an "optical adjustment layer" 13") is disposed between the resin substrate 11 and the functional layer 12 and adjacent to the functional layer 12. Further, the optical film 10 shown in FIG. 1 further includes a second optical adjustment layer 14 (hereinafter sometimes referred to simply as "optical adjustment layer 14"), which is provided on the resin substrate 11 and the first optical adjustment layer 13 Between the resin substrate 11 and the third optical adjustment layer 15 (hereinafter, simply referred to as "optical adjustment layer 15"), the resin substrate 11 is provided opposite to the first surface 11A. The second surface 11B of the side surface. The second optical adjustment layer 14 and/or the third optical adjustment layer 15 may not be provided. Further, the optical film 10 may further include a resin layer on the second surface 11B side of the resin substrate 11 as shown by the optical film 40 described below. The term "functional layer" as used herein refers to a layer that is intended to exhibit certain functions in an optical film. Specifically, examples of the functional layer include a hard coat layer, an antistatic layer, and an antifouling layer. The functional layer 12 functions as a hard coat layer. Further, the functional layer 12 has a single-layer structure, but the functional layer may have a single-layer structure or a multilayer structure of two or more layers. Moreover, each "optical adjustment layer" in this specification has a single-layer structure, and is not a multilayer structure of two or more layers. In addition, in FIG. 1, the two optical adjustment layers of the first optical adjustment layer 13 and the second optical adjustment layer 14 are provided between the resin substrate 11 and the functional layer 12, and may be applied to the first optical adjustment layer 13 and Further, another optical adjustment layer or the like is provided between the second optical adjustment layers 14 to have a structure of three or more layers.

In Fig. 1, the front surface 10A of the optical film 10 becomes the front surface 12A of the functional layer 12. Further, in the present specification, the front surface of the optical film is used in the meaning of the surface on one side of the optical film. Therefore, the surface of the optical film opposite to the front surface is referred to as a back surface to be distinguished from the front surface of the optical film. The back surface 10B of the optical film 10 is a surface 15A on the opposite side to the surface of the optical adjustment layer 15 on the side of the resin substrate 11.

The optical film 10 is foldable. Specifically, it is preferable to continuously fold the optical film 10 so that the functional layer 12 is inside and the interval between the opposite sides of the optical film 10 is 10 mm (continuous folding test). In the case of the film 10, cracking or cracking does not occur in the optical film 10, and it is more preferable that the film 10 does not crack or break even when the continuous folding test is repeated 20,000 times. The optical film 10 is not broken or broken when it is repeatedly performed 100,000 times. When the optical film 10 is repeatedly subjected to a continuous folding test of 10,000 times, if the optical film 10 is cracked or the like, the folding property of the optical film 10 becomes insufficient. In addition, it is preferable that the test (continuous folding test) in which the optical film 10 is continuously folded so that the functional layer 12 is outside and the interval between the opposite sides of the optical film 10 is 30 mm is repeated 10,000 times. At the same time, cracking or breaking of the optical film 10 is not caused, and it is more preferable that cracking or cracking does not occur in the optical film 10 even when the continuous folding test of 20,000 times is repeated, and it is preferable to repeat When the case is performed 100,000 times, cracking or breakage of the optical film 10 is not caused.

The continuous folding test in which the optical film 10 is continuously folded so that the functional layer 12 becomes the inner side is performed as follows. As shown in Fig. 2(A), in the continuous folding test, first, the side portion 10C of the optical film 10 and the side portion 10D opposed to the side portion 10C are fixed by the fixing portions 20 arranged in parallel. Further, the optical film 10 may have any shape, but the optical film 10 in the continuous folding test is preferably rectangular (for example, a rectangle of 30 mm × 100 mm). Further, as shown in FIG. 2(A), the fixing portion 20 is slidably movable in the horizontal direction.

Then, as shown in FIG. 2(B), the fixing portion 20 is moved toward each other, and the functional layer 12 is formed inside, that is, the front surface 10A of the optical film 10 is inside and the optical film 10 is folded. Further, as shown in FIG. 2(C), after the fixing portion 20 is moved to a position where the distance between the two opposite sides fixed by the fixing portion 20 of the optical film 10 is 10 mm, the fixing portion 20 is moved in the reverse direction. The deformation of the optical film 10 is released.

The optical film 10 can be folded by 180° by moving the fixing portion 20 as shown in Figs. 2(A) to (C). Further, the continuous folding test is performed so that the bent portion 10E of the optical film 10 does not protrude from the lower end of the fixing portion 20, and the interval at which the fixing portion 20 is closest is controlled to 10 mm, whereby the optical film 10 can be paired. The interval between the two sides is 10 mm. In this case, the outer diameter of the curved portion 10E is regarded as 10 mm. Further, since the thickness of the optical film 10 is sufficiently smaller than the interval (10 mm) of the fixing portion 20, it is considered that the result of the continuous folding test of the optical film 10 is not affected by the difference in thickness of the optical film 10. . In the case of the optical film 10, it is preferable that the continuous folding test is performed by folding 180° so that the functional layer 12 is inside and the interval between the opposite sides of the optical film 10 is 10 mm. It is preferable that cracking or fracture occurs, and it is preferable that rupture is performed 10,000 times in a case where the functional layer 12 is inside and the interval between the opposite sides of the optical film 10 is 2 mm. Or break.

In the optical film 10, as shown in Fig. 3(A), the side portion 10C of the optical film 10 and the side portion 10D facing the side portion 10C are used so that the distance between the side portion 10C and the side portion 10D becomes 10 mm. The fixing portion 25 arranged in parallel was fixed and folded in the state of the optical film 10, and the folding standing test was carried out at 70 ° C for 12 hours, as shown in Fig. 3 (B), by the folding and standing test. When the fixing portion 25 is removed from the fixing portion 25 and the folded state is released, the optical film 10 is preferably an angle at which the optical film 10 is naturally opened, that is, the opening angle θ, after 30 minutes at room temperature. The opening angle θ is 100° or more. Furthermore, the larger the opening angle θ, the better the recovery, and the maximum is 180°. The folding and standing test may be performed by folding the optical film 10 such that the functional layer 12 is inside, or may be performed by folding the optical film 10 such that the functional layer 12 is outside, preferably in any case. The opening angle θ is 100° or more.

The front surface 10A of the optical film 10 (front surface 12A of the functional layer 12) preferably has a hardness (pencil hardness) of 3H or more when measured by a pencil hardness test prescribed in JIS K5600-5-4:1999, more preferably 4H or more. The pencil hardness test was carried out by using the optical film 10 cut out at a size of 30 mm × 100 mm to use Cellotape (registered trademark) manufactured by Nichiban Co., Ltd. without bending or wrinkling on the glass plate. For the front side of the optical film, use a pencil hardness tester (product name "Pencil Scratch Film Hardness Tester (Electric)", manufactured by Toyo Seiki Co., Ltd.), and face the pencil (product name "Uni" , manufactured by Mitsubishi Pencil Co., Ltd.), while applying a load of 750 g, the pencil was moved at a moving speed of 1 mm/sec. The pencil hardness was set to the highest hardness that did not cause damage to the front side of the optical film in the pencil hardness test. Furthermore, in the measurement of the pencil hardness, it is determined by using a plurality of pencils having different hardnesses, and the pencil hardness test is performed once for each pencil, and when the damage occurs on the front side of the optical film four times or more in five times, it is judged. A pencil of this hardness causes damage to the front side of the optical film. The above-mentioned damage is determined by penetrating the front surface of the optical film subjected to the pencil hardness test under a fluorescent lamp.

The surface resistance of the front surface 10A of the optical film 10 is preferably 10 ¹² Ω/□ or less. The surface resistance value can be measured in accordance with JIS K6911:2006 using a resistivity meter (product name "Hiresta-UP MCP-HT450", manufactured by Mitsubishi Chemical Analytech Co., Ltd., probe: URS). The surface resistance value of the front surface 10A of the optical film 10 was measured by randomly measuring the surface resistance value of the front surface 10A of the optical film 10 cut out at a size of 50 mm × 50 mm in 10 portions, and the surface resistance values of the measured 10 portions were used. Arithmetic mean.

In the optical film 10, at a temperature of 23 ° C and a relative humidity of 50%, a saturated charge voltage of the front surface 10A of the optical film 10 when a voltage of 10 kV is applied from a front surface 10A of the optical film 10 of 50 mm (saturated charge voltage) It is preferably more than 0 kV. Further, similarly, in the environment of 23 ° C and a relative humidity of 50%, the saturation band voltage of the back surface 10B of the optical film 10 when a voltage of 10 kV is applied from the back surface 10B of the optical film 10 of 20 mm is preferably more than 0 kV. . The so-called saturation band voltage refers to the maximum voltage that the optical film can store. When an optical film having an antistatic hard coat layer is disposed on the observer side of the touch sensor, there is a position detection of a finger or the like using the touch sensor due to the antistatic hard coat layer. However, if the saturation band voltage of the front surface 10A of the optical film 10 exceeds 0 kV, the touch sensing can be performed even when the optical film 10 is disposed on the observer side of the touch sensor. Position detection of the finger of the device. The saturation band voltage can be measured using a charged charge decay meter (product name "H-0110", manufactured by Shishido Electrostatic Co., Ltd.). The saturation band voltage was set to the arithmetic mean value of the value obtained by measuring the optical film cut out at a size of 100 mm × 100 mm three times. The lower limit of the saturation band voltage is preferably 0.1 kV or more, and the upper limit of the saturation band voltage is more preferably 3 kV or less.

The yellow index (YI) of the optical film 10 is preferably 15 or less. When the YI of the optical film 10 is 15 or less, the yellow tone of the optical film can be suppressed, and it can be applied to applications requiring transparency. The upper limit of the yellow index (YI) of the optical film 10 is more preferably 10 or less. The yellow index (YI) is a value calculated by the spectrophotometer (product name "UV-2450", Shimadzu, in which the back side of the optical film cut out in a size of 50 mm × 100 mm is the light source side. Manufactured by the company, light source: tungsten lamp and xenon lamp), according to the transmittance of the optical film measured in this state, the wavelength of 300 nm to 780 nm, according to the calculation formula described in JIS Z8722:2009, calculate the chromaticity three The stimulation values X, Y, and Z are calculated from the tristimulus values X, Y, and Z according to the arithmetic expressions described in ASTM D1925:1962. The upper limit of the yellow index (YI) of the optical film 10 is more preferably 10 or less. The yellow index (YI) is an arithmetic mean obtained by measuring three optical films three times and using three measurements. Further, in the UV-2450, the yellow index is calculated by reading the measurement data of the above-mentioned transmittance by connecting to the monitor of the UV-2450, and checking the item of "YI" in the calculation item. The measurement of the transmittance of the wavelength of 300 nm to 780 nm was carried out by measuring the transmittance of the lowest 5 points between 1 nm before and after the wavelength of 300 nm to 780 nm under the following conditions, and calculating the average value. value. Further, if the spectrum of the spectral transmittance is undulated, the smoothing treatment can be performed at δ 5.0 nm.

(measurement conditions)

‧wavelength region: 300nm~780nm

‧Scanning speed: high speed

‧ slit width: 2.0

‧Sampling interval: automatic (0.5nm interval)

‧Lighting: C

‧Light source: D2 and WI

‧Field of view: 2°

‧Light source switching wavelength: 360nm

‧S/R switching: standard

‧Detector: PM

‧Automatic zero: After the baseline scan, it is implemented at 550nm

In order to adjust the yellow index (YI) of the optical film 10, for example, at least one of the resin substrate 11, the functional layer 12, and the optical adjustment layers 13 and 14 may contain a blue coloring matter which is a yellow complementary color. In other words, when the yellow matrix is caused to be a problem due to the use of the polyimide substrate as the resin substrate, the yellow index (YI) of the optical film can be lowered by including the blue pigment in the resin substrate 11 or the like. .

The blue dye may be either a pigment or a dye. For example, when the optical film 10 is used in an organic light-emitting diode display device, it is preferable to have both light resistance and heat resistance. As the blue dye, a polycyclic organic pigment or a metal complex organic pigment has a smaller degree of molecular cleavage due to ultraviolet rays than a molecular dispersion of a dye, and is particularly excellent in light resistance, and therefore requires light resistance and the like. The use is preferred, and more specifically, a phthalocyanine-based organic pigment or the like is preferably used. However, since the pigment disperses the particles in the solvent, there is a hindrance to transparency caused by scattering of the particles. Therefore, it is preferred that the particle size of the pigment dispersion is located in the Rayleigh scattering region. On the other hand, in the case where the transparency of the optical film is emphasized, it is preferred to use a dye which generates molecular dispersion with respect to a solvent as the blue dye. Further, as the blue dye, an inorganic pigment such as cobalt blue may be used.

From the side of the optical adjustment layer 15 toward the optical film 10, a region having a wavelength of 300 nm or more and 780 nm or less is irradiated with light having a continuous spectrum at an incident angle of 0°, and L ^* a of light (penetrating light) penetrating the optical film 10 is obtained ^{. *} b ^* color coordinates a ^* and b ^* of the color system. In this case, a ^* is preferably -3.0 or more and 2.0 or less, and b ^* is -2.0 or more and 8.0 or less. If a ^* and b ^* are each within the above range, the yellow index can be 15 or less. The measurement of a ^* and b ^* can be carried out using a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation). As the light source, a tungsten halogen (WI) lamp alone, or a xenon (D2) lamp and a tungsten halogen (WI) lamp may be used in combination. In the present specification, the term "light having an incident angle of 0" means light in the normal direction when the normal direction of the first surface of the optical film is 0°. "L ^* a ^* b ^* color system", "a ^* " and "b ^* " are based on JIS Z8729:2004.

The optical transmittance of the optical film 10 at a wavelength of 380 nm is preferably 8% or less. When the spectral transmittance of the optical film exceeds 8%, when the optical film is used for a mobile terminal, the polarizing element is exposed to ultraviolet rays and is easily deteriorated. The above-mentioned transmittance can be measured using a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation). The measurement conditions of the spectral transmittance are the same as those for the spectral transmittance of the wavelength of 300 nm to 780 nm. The above-mentioned transmittance was measured three times for an optical film cut out at a size of 50 mm × 100 mm, and the arithmetic mean value of the value obtained by measuring three times was used. The upper limit of the above transmittance of the optical film 10 is more preferably 5%. Further, the above-described transmittance of the optical film 10 can be achieved by adjusting the amount of addition of the ultraviolet absorber described below or the like.

The total light transmittance of the optical film 10 is preferably 85% or more. If the total light transmittance of the optical film 10 is 85% or more, sufficient image visibility can be obtained when the optical film 10 is used for a mobile terminal. The total light transmittance of the optical film 10 is preferably 87% or more, and most preferably 90% or more.

The total light transmittance can be measured by a method according to JIS K7361-1:1997 using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Co., Ltd.). The total light transmittance is obtained by cutting the optical film at a size of 50 mm × 100 mm, and then setting it without curling or wrinkling and without fingerprints or dust, and measuring one optical film three times, and measuring three times. And the arithmetic mean of the values obtained. In the present specification, "measuring three times" does not measure the same portion three times, but refers to measuring three different portions. In the optical film 10, the front surface 10A of the visual inspection is flat, and the layers of the functional layer 12 and the like are also flat, and the unevenness of the film thickness also converges within the range of ±10%. Therefore, it is considered that the average value of the total light transmittance of the entire in-plane of the optical film can be obtained by measuring the total light transmittance from the three different portions of the cut optical film. Regardless of the length of the measurement object of 1m × 3000m, or the size of a 5 inch smart phone, the unevenness of the total light transmittance is within ±10%. Furthermore, when the optical film is not cut out in the above-mentioned size, for example, the entrance opening is 20 mm when measured by the HM-150. Therefore, it is necessary to have a sample size such as a diameter of 21 mm or more. Therefore, the optical film can be appropriately cut out in a size of 22 mm × 22 mm or more. When the size of the optical film is small, the measurement point is set to three positions by slightly shifting or changing the angle or the like without departing from the point of the light source.

The haze value (total haze value) of the optical film 10 is preferably 2.5% or less. When the haze value of the optical film is 2.5% or less, whitening of the image display surface can be suppressed when the optical film is used for the mobile terminal. The haze value is more preferably 1.5% or less, still more preferably 1.0% or less.

The haze value can be measured by a method according to JIS K7136:2000 using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Co., Ltd.). The haze value is obtained by cutting the optical film at a size of 50 mm × 100 mm, and is provided without curling or wrinkling and without fingerprints or dust. Three optical films are measured three times, and three measurements are obtained. The arithmetic mean of the values. In the optical film 10, the front surface 10A of the visual inspection is flat, and the layers of the functional layer 12 and the like are also flat, and the unevenness of the film thickness also converges within the range of ±10%. Therefore, it is considered that the average haze value of the entire in-plane of the optical film can be obtained by measuring the haze value at three different portions of the cut optical film. Regardless of the length of the measurement object of 1 m × 3000 m, or the size of a smart phone of 5 inches, the unevenness of the haze value is within ±10%. Furthermore, when the optical film is not cut out in the above-mentioned size, for example, the entrance opening is 20 mm when measured by the HM-150. Therefore, it is necessary to have a sample size such as a diameter of 21 mm or more. Therefore, the optical film can be appropriately cut out in a size of 22 mm × 22 mm or more. When the size of the optical film is small, the measurement point is set to three positions by slightly shifting or changing the angle or the like without departing from the point of the light source.

When another film such as a polarizing plate is provided on the first surface side of the optical film 10 via the adhesive layer or the adhesive layer, the other film is peeled off together with the adhesive layer or the adhesive layer, and then a folding test, a folding rest test, and a folding test are performed. Yellow index measurement, total light transmittance measurement, haze value measurement. Peeling of the other film can be carried out, for example, in the following manner. First, a laminate having another film attached to the optical film via an adhesive layer or an adhesive layer is heated by a dryer, and the edge of the cutter is cut into a portion which is regarded as an interface between the optical film and the other film, and is slowly peeled off. By repeating such heating and peeling, the adhesive layer or the adhesive layer and other films can be peeled off. Furthermore, even with such a stripping step, there is no significant effect on such tests or such measurements. The haze value is measured after the adhesion of the adhesive layer or the adhesive layer, and then the stain of the adhesive layer or the adhesive layer is sufficiently wiped with alcohol.

In recent years, a light emitting diode (Light Emitting Diode) has been actively used as a light source for a backlight of an image display device such as a personal computer or a tablet terminal, but the light emitting diode strongly emits light called blue light. It is known that the blue light is light having a wavelength of 380 nm to 495 nm and has a property close to ultraviolet rays, and has strong energy, so that it is not absorbed by the cornea or the lens and reaches the retina, thereby causing retinal damage, eye fatigue, and poor sleep. The reason for the impact, etc. Therefore, when the optical film is applied to an image display device, it is preferable that the color tone of the display screen is not affected, and the blue light shielding property is excellent. Therefore, in terms of shielding blue light, the optical film 10 preferably has a light transmittance of less than 1% at a wavelength of 380 nm, a light transmittance of less than 10% at a wavelength of 410 nm, and a light transmittance of 70% at a wavelength of 440 nm. the above. The reason for this is that if the spectral transmittance of the wavelength of 380 nm is 1% or more, or the wavelength of the wavelength of 410 nm is 10% or more, the problem caused by blue light cannot be solved, and if the wavelength of 440 nm is transmitted, the light is transmitted. When the transmittance is less than 70%, there is a case where the color tone of the display screen of the image display device using the optical film is affected. The optical film 10 can sufficiently absorb light of a wavelength region having a wavelength of 410 nm or less in the wavelength of blue light, and can sufficiently transmit light having a wavelength of 440 nm or more without affecting the color tone of the display screen. The blue light is excellent in shielding. Further, when such an optical film 10 excellent in blue light shielding property is applied to an organic light emitting diode (OLED) display device as an image display device, it is effective for suppressing deterioration of the organic light emitting diode element.

The light transmittance of the optical film 10 is preferably almost 0% up to a wavelength of 380 nm, and the light penetration gradually increases from a wavelength of 410 nm, and the light penetration becomes sharp near a wavelength of 440 nm. Specifically, for example, it is preferably between 410 nm and 440 nm in wavelength, and the spectral transmittance changes in such a manner as to describe an S-shaped curve. The light transmittance of the above-mentioned wavelength of 380 nm is more preferably less than 0.5%, further preferably less than 0.2%, and the light transmittance of the wavelength of 410 nm is preferably less than 7%, more preferably less than 5%, and the wavelength is 440 nm. The light transmittance is more preferably 75% or more, and still more preferably 80% or more. Further, the optical film 10 preferably has a spectral transmittance of less than 50% at a wavelength of 420 nm. By satisfying such a relationship of the spectral transmittance, the optical film 10 has a sharp increase in transmittance at a wavelength of around 440 nm, and it is possible to obtain an extremely excellent blue light shielding property without affecting the color tone of the display screen.

The optical transmittance of the optical film 10 at a wavelength of 380 nm is preferably less than 0.1%, the light transmittance at a wavelength of 410 nm is preferably less than 7%, and the light transmittance at a wavelength of 440 nm is more preferably 80% or more.

Preferably, the optical film 10 has a slope of a transmission spectrum in the range of 415 to 435 nm obtained using a least squares method of greater than 2.0. When the slope is 2.0 or less, the wavelength region of the blue light, for example, the wavelength region of the wavelength of 415 to 435 nm, may not sufficiently cut off the light, and the blue light-off effect may be weak. Moreover, the possibility of excessively blocking the wavelength region of the blue light (wavelength 415 to 435 nm) is also considered. In this case, a backlight or an emission wavelength region of the image display device (for example, a light emission of 430 nm from the OLED) is generated. The possibility of interference such as interference or hue deterioration becomes large. The above-mentioned slope can be measured by, for example, a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation) which can be measured at a wavelength of 0.5 nm, and a minimum of 5 points between 1 nm before and after 1 nm between 415 and 435 nm. Calculated by the data.

The blue film shielding ratio of the optical film 10 is preferably 40% or more. If the blue light shielding rate is less than 40%, there is a case where the above problem caused by blue light cannot be sufficiently solved. The blue light shielding rate is, for example, a value calculated by JIS T7333:2005. Further, such a blue light shielding rate can be achieved, for example, by allowing the functional layer 12 to contain the following sesame phenol type benzotriazole-based monomer.

The use of the optical film 10 is not particularly limited, and examples of the use of the optical film 10 include a smart phone, a tablet terminal, a personal computer (PC), a wearable terminal, a digital signage, a television, and a car navigation device. Moreover, the optical film 10 is also suitable for vehicle use. As the form of each of the image display devices described above, it is also preferable in terms of the use of flexibility, such as folding and curling.

The optical film 10 can be cut to a desired size or in a roll shape. When the optical film 10 is cut into a desired size, the size of the optical film is not particularly limited and may be appropriately determined depending on the size of the display surface of the image display device. Specifically, the size of the optical film 10 may be, for example, 2.8 inches or more and 500 inches or less. In the present specification, the term "inch" refers to the length of the diagonal when the optical film has a quadrangular shape, and refers to the diameter in the case of a circular shape, and refers to the short diameter and length in the case of an elliptical shape. The average of the sum of the paths. Here, in the case where the optical film has a rectangular shape, the aspect ratio of the optical film when the above-mentioned inch is obtained is not particularly limited as long as there is no problem as a display screen of the image display device. For example, vertical: horizontal = 1: 1, 4: 3, 16: 10, 16:9, 2: 1, and the like. Among them, especially in the design-rich vehicle use or digital signage, it is not limited to such an aspect ratio. Further, when the size of the optical film 10 is large, it is cut out from an arbitrary position at an A5 size (148 mm × 210 mm), and then cut out in the size of each measurement item.

The arrangement of the optical film 10 in the image display device may also be inside the image display device, preferably near the surface of the image display device. When used in the vicinity of the surface of the image display device, the optical film 10 functions as a cover film used instead of the cover glass.

<<Resin substrate>>

The resin substrate 11 has light transmissivity. The term "transparency" as used in the present specification means a property of penetrating light, and includes, for example, a total light transmittance of 50% or more, preferably 70% or more, more preferably 80% or more, and still more preferably 90% or more. The so-called light transmission is not necessarily transparent, but may be translucent.

The resin substrate 11 is selected from the group consisting of a polyimide resin, a polyamide amide resin, a polyamide resin, and a polyester resin (for example, polyethylene terephthalate resin or polyphthalene resin). A substrate composed of one or more resins selected from the group consisting of ethylene formate resins.

In these resins, not only cracking or cracking is unlikely to occur in the continuous folding test, but also excellent hardness and transparency, and excellent heat resistance, and more excellent hardness and transparency can be imparted by calcination. From the viewpoint of properties, a polyimide-based resin, a polyamine-based resin, or a mixture thereof is preferred.

The polyimide-based resin is obtained by reacting a tetracarboxylic acid component with a diamine component. The polyimine-based resin is not particularly limited. For example, in terms of excellent light transmittance and excellent rigidity, it is preferably selected from the following general formula (1) and the following general formula (3). At least one of the group consisting of the structures represented.

In the above formula (1), R ¹ represents a tetravalent group as a tetracarboxylic acid residue, and R ² represents a residue selected from a trans-cyclohexanediamine residue, trans-1,4-bismethylene. a cyclohexanediamine residue, a 4,4′-diaminodiphenylfluorene residue, a 3,4′-diaminodiphenylfluorene residue, and a second represented by the following formula (2) At least one divalent group of the group consisting of valence groups. n represents the number of repeating units and is 1 or more. In the present specification, the term "tetracarboxylic acid residue" means a residue obtained by removing four carboxyl groups from a tetracarboxylic acid, and has the same structure as a residue obtained by removing an acid dianhydride structure from a tetracarboxylic dianhydride. Moreover, the "diamine residue" means a residue obtained by removing two amine groups from a diamine.

In the above formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group or a perfluoroalkyl group.

In the above formula (3), R ⁵ represents a residue selected from the group consisting of a cyclohexane tetracarboxylic acid residue, a cyclopentane tetracarboxylic acid residue, and a dicyclohexane-3,4,3',4'-tetracarboxylic acid. At least one tetravalent group of the group consisting of a residue and a 4,4'-(hexafluoroisopropylidene)diphthalic acid residue, and R ⁶ represents a divalent group as a diamine residue. n' represents the number of repeating units and is 1 or more.

R ¹ in the above formula (1) is a tetracarboxylic acid residue, and may be a residue obtained by removing the acid dianhydride structure from the tetracarboxylic dianhydride as exemplified above. R ¹ in the above formula (1), wherein in terms of improving light transmittance and improving rigidity, it is preferred to contain a compound selected from 4,4'-(hexafluoroisopropylidene)diphthalic acid Residue, 3,3',4,4'-biphenyltetracarboxylic acid residue, pyromellitic acid residue, 2,3',3,4'-biphenyltetracarboxylic acid residue, 3,3' , 4,4'-benzophenone tetracarboxylic acid residue, 3,3',4,4'-diphenylphosphonium tetracarboxylic acid residue, 4,4'-oxydiphthalic acid residue, At least one selected from the group consisting of a cyclohexane tetracarboxylic acid residue and a cyclopentane tetracarboxylic acid residue, and more preferably contains a terminal selected from 4,4'-(hexafluoroisopropylidene) At least one of a group consisting of a phthalic acid residue, a 4,4'-oxydiphthalic acid residue, and a 3,3',4,4'-diphenylphosphonium tetracarboxylic acid residue.

In R ¹ , the preferred residue is preferably contained in an amount of 50 mol% or more, more preferably 70 mol% or more, and still more preferably 90 mol% or more.

Further, as R ¹ , it is also preferred to be selected from the group consisting of a 3,3',4,4'-biphenyltetracarboxylic acid residue and a 3,3',4,4'-benzophenone tetracarboxylic acid residue. At least one of the group consisting of a base and a pyromellitic acid residue is suitable for increasing the group of rigid tetracarboxylic acid residues (Group A), and is selected, for example, from 4,4'-(hexafluoroisophthalene) Propyl)diphthalic acid residue, 2,3',3,4'-biphenyltetracarboxylic acid residue, 3,3',4,4'-diphenylphosphonium tetracarboxylic acid residue, 4 a tetracarboxylic acid suitable for improving transparency by at least one of a group consisting of a 4'-oxydiphthalic acid residue, a cyclohexanetetracarboxylic acid residue, and a cyclopentane tetracarboxylic acid residue The residue group (group B) is mixed and used.

In this case, the content ratio of the tetracarboxylic acid residue group (group A) suitable for improving the rigidity and the tetracarboxylic acid residue group (group B) suitable for improving transparency is suitable for improving transparency. The tetracarboxylic acid residue group (group B) is 1 mol, and the tetracarboxylic acid residue group (group A) suitable for increasing the rigidity is preferably 0.05 mol or more and 9 mol or less, and more preferably 0.1 mol or more and 5 mol or less, and more preferably 0.3 mol or more and 4 mol or less.

R ² in the above formula (1), wherein, in terms of improving light transmittance and improving rigidity, it is preferably selected from the group consisting of 4,4'-diaminodiphenyl fluorene residues, 3, 4 At least one divalent group of the group consisting of a '-diaminodiphenyl fluorene residue and a divalent group represented by the above formula (2), and more preferably selected from 4, 4'-di An aminodiphenylphosphonium residue, a 3,4'-diaminodiphenylphosphonium residue, and a divalent group represented by the above formula (2) wherein R ³ and R ⁴ are a perfluoroalkyl group At least one divalent group in the group.

R ⁵ in the above formula (3), wherein 4,4'-(hexafluoroisopropylidene)diphthalic acid residue is preferably contained in terms of improving light transmittance and improving rigidity , 3,3',4,4'-diphenylstilbene tetracarboxylic acid residue, and oxydiphthalic acid residue.

In R ⁵ , these preferred residues preferably contain 50 mol% or more, more preferably 70 mol% or more, and still more preferably 90 mol% or more.

R ⁶ in the above formula (3) is a diamine residue, and may be a residue obtained by removing two amine groups from the diamine as exemplified above. The general formula R (3) in the ^6, wherein, to increase the rigidity in terms of improving the light-transmitting and the aspect is preferably selected from the group comprising 2,2'-bis (trifluoromethyl) benzidine residue, Bis[4-(4-aminophenoxy)phenyl]indole residue, 4,4'-diaminodiphenylfluorene residue, 2,2-bis[4-(4-aminophenoxyl) Phenyl]hexafluoropropane residue, bis[4-(3-aminophenoxy)phenyl]indole residue, 4,4'-diamino-2,2'-bis(trifluoromethyl) Diphenyl ether residue, 1,4-bis[4-amino-2-(trifluoromethyl)phenoxy]benzene residue, 2,2-bis[4-(4-amino-2) -trifluoromethylphenoxy)phenyl]hexafluoropropane residue, 4,4'-diamino-2-(trifluoromethyl)diphenyl ether residue, 4,4'-diaminobenzene a group consisting of a anilide residue, an N,N'-bis(4-aminophenyl)terephthalamide residue, and a 9,9-bis(4-aminophenyl)fluorene residue At least one divalent group, more preferably containing a residue selected from 2,2'-bis(trifluoromethyl)benzidine, bis[4-(4-aminophenoxy)phenyl]fluorene At least one divalent group of the group consisting of a residue and a 4,4'-diaminodiphenyl fluorene residue.

In R ⁶ , the total of the preferred residues is preferably 50% by mole or more, more preferably 70% by mole or more, and still more preferably 90% by mole or more.

Further, as R ⁶ , it is also preferred to be selected from the group consisting of a bis[4-(4-aminophenoxy)phenyl]fluorene residue, a 4,4'-diaminobenzimidamide residue, and N. , N'-bis(4-aminophenyl)terephthalamide residue, p-phenylenediamine residue, m-phenylenediamine residue, and 4,4'-diaminodiphenylmethane residue At least one of the groups consisting of groups is suitable for increasing the rigidity of the diamine residue group (Group C), and, for example, from the 2,2'-bis(trifluoromethyl)benzidine residue, 4, 4'-Diaminodiphenylhydrazine residue, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane residue, bis[4-(3-aminophenoxyl) Phenyl] anthracene residue, 4,4'-diamino-2,2'-bis(trifluoromethyl)diphenyl ether residue, 1,4-bis[4-amino-2-( Trifluoromethyl)phenoxy]benzene residue, 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane residue, 4,4' At least one of a group consisting of a diamino-2-(trifluoromethyl)diphenyl ether residue and a 9,9-bis(4-aminophenyl)fluorene residue is suitable for improving transparency The diamine residue group (Group D) is mixed and used.

In this case, the content ratio of the diamine residue group (group C) suitable for improving the rigidity and the diamine residue group (group D) suitable for improving transparency is suitable for improving transparency. The diamine residue group (Group D) is 1 mol, and the diamine residue group (Group C) suitable for increasing the rigidity is preferably 0.05 mol or more and 9 mol or less, and more preferably 0.1 mol or more. And less than 5 moles, more preferably 0.3 moles or more and 4 moles or less.

In the structures represented by the above formula (1) and the above formula (3), n and n' each independently represent the number of repeating units and are 1 or more. The number n of repeating units of the polyimine is not particularly limited as long as it is appropriately selected depending on the structure so as to indicate a preferred glass transition temperature. The average repeating unit number is usually from 10 to 2,000, and more preferably from 15 to 1,000.

Further, the polyamidene-based resin may have a polyamine structure in a part thereof. Examples of the polyamine structure which may be contained include a polyamidoquinone imine structure containing a tricarboxylic acid residue such as trimellitic anhydride, or a polyfluorene containing a dicarboxylic acid residue such as terephthalic acid. Amine structure.

The glass transition temperature of the polyimine-based resin is preferably 250 ° C or higher, and more preferably 270 ° C or higher in terms of heat resistance. On the other hand, the glass transition temperature is preferably 400 ° C or lower, and more preferably 380 ° C or lower in terms of easiness of stretching or lowering of baking temperature.

The polyimine-based resin may, for example, be a compound having a structure represented by the following formula. In the following formula, n is a repeating unit and represents an integer of 2 or more.

In the above polyimine-based resin, in terms of excellent transparency, a polyimine-based resin or a polyamine-based resin having a structure which does not easily cause intramolecular or intermolecular charge transfer is preferable. Specifically, a fluorinated polyimine-based resin such as the above formulas (4) to (11) and a polyfluorene-based resin having an alicyclic structure such as the above formulas (13) to (16) may be mentioned.

Further, in the fluorinated polyimine-based resin such as the above formulas (4) to (11), since it has a fluorinated structure, it has high heat resistance and is not caused by a polyimide resin. The polyimine film which is formed is colored by heat, and therefore has excellent transparency.

The concept of polyamine resins includes not only aliphatic polyamines but also aromatic aramids. Examples of the polyamine-based resin include compounds having a skeleton represented by the following formulas (21) to (23). Further, in the following formula, n is a repeating unit and represents an integer of 2 or more.

A substrate composed of the polyimine-based resin or the polyamine-based resin represented by the above formulas (4) to (20) and (23) can also be used commercially. For example, a commercially available product of a base material composed of the above-mentioned polyimide resin, such as Neopulim manufactured by Mitsubishi Gas Chemical Co., Ltd., may be mentioned as a commercially available product of a base material composed of the above polyamine resin. A Mictron manufactured by Toray Co., Ltd., etc. are mentioned.

Further, the polyimide-based resin or the polyamine-based resin represented by the above formulas (4) to (20) and (23) may be synthesized by a known method. For example, a method for synthesizing a polyimide-based resin represented by the above formula (4) is disclosed in JP-A-2009-132091, and specifically, 4, 4'-six represented by the following formula (24) can be used. Fluorinated bisphthalic dianhydride (FPA) is obtained by reacting 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB).

The weight average molecular weight of the polyimine-based resin or the polyamine-based resin is preferably in the range of 3,000 or more and 500,000 or less, more preferably in the range of 5,000 to 300,000, and still more preferably 10,000 or more and less than 200,000. The scope. When the weight average molecular weight is less than 3,000, sufficient strength may not be obtained. When the weight average molecular weight exceeds 500,000, the viscosity is increased and the solubility is lowered. Therefore, there is a case where a substrate having a smooth surface and a uniform film thickness cannot be obtained. In the present specification, the "weight average molecular weight" means a polystyrene equivalent value measured by gel permeation chromatography (GPC).

The resin base material 11 is preferably a fluorinated polyimine resin represented by the above formulas (4) to (11) or the like, or a halogen group such as the above formula (23). A substrate composed of a polyamide resin. In addition, it is more preferable to use the base material which consists of the poly

Examples of the polyester-based resin include at least one of polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Resin of ingredients, etc.

The refractive index of the resin substrate 11 is higher than the refractive index of the functional layer 12. The refractive index of the resin substrate 11 can be measured, for example, by the Beck method. When the refractive index of the resin substrate 11 was measured by the Beck method, pieces of 10 resin substrates 11 were cut out, and for the 10 pieces cut, a refractive index standard solution was used, and the refractive index was measured by the Beck method. The average value of the refractive indices of the 10 pieces measured was taken as the refractive index of the resin substrate 11. The refractive index of the resin substrate 11 may be 1.500 or more and 1.800 or less. Further, the refractive index of the resin substrate 11 can be measured by using a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation) at an average reflectance of a wavelength of 380 to 780 nm, and the obtained average reflectance can be used as follows. It is obtained by the formula (1). In order to prevent back reflection, the average reflectance (R) of the resin substrate 11 is set to a black polyvinyl chloride tape having a width larger than the area of the measurement point (for example, the product name "Yamato vinyl tape NO200-38-21", It was measured by attaching it to the back surface of the resin substrate 11 by the Yamato company, 38 mm width.

R ₁ =(1-n ₁ ) ² /(1+n ₁ ) ² (1)

In the above formula (1), R ₁ represents an average reflectance (%) of a resin substrate having a wavelength of 380 to 780 nm, and n ₁ represents a refractive index of the resin substrate.

The thickness of the resin substrate 11 is preferably 10 μm or more and 100 μm or less. When the thickness of the resin substrate is 10 μm or more, curling of the optical film can be suppressed, and sufficient hardness can be obtained, and even when an optical film is produced by a roll-to-roll method, wrinkles are less likely to occur. There is no flaw that causes deterioration in appearance. On the other hand, when the thickness of the resin substrate is 100 μm or less, the folding property of the optical film is good, which satisfies the requirements of the continuous folding test, and is preferable in terms of weight reduction of the optical film. The thickness of the resin substrate 11 is obtained by scanning a cross section of the resin substrate 11 using a scanning electron microscope (SEM), and the film thickness of the resin substrate 11 at ten locations is measured in the image of the cross section, and the film of the ten portions is used. The arithmetic mean of the thickness. The lower limit of the resin substrate 11 is more preferably 25 μm or more, and the upper limit of the resin substrate 11 is more preferably 80 μm or less.

<<Function layer>>

The functional layer 12 is a layer that functions as a hard coat layer. The functional layer 12 may have functions other than hard coat properties in addition to hard coat properties. The functional layer 12 also has antistatic properties in addition to hard coat properties. That is, the functional layer 12 becomes an antistatic hard coat layer. In the present specification, the term "hard coat layer" means a layer having a Martens hardness of 375 MPa or more in the center of the cross section of the hard coat layer. In the present specification, the term "Martens hardness" means the hardness when the indenter is pressed into a thickness of 500 nm by the hardness measurement by the nanoindentation method. The measurement of the Martens hardness by the above-described nanoindentation method was carried out by using "TI950 TriboIndenter" manufactured by HYSITRON Co., Ltd. for the measurement of the sample. Specifically, first, a block in which an optical film cut at 1 mm × 10 mm is embedded in an embedding resin is produced, and a uniform thickness of a hole or the like is cut out from the block by a general slicing method. Slices of 70 nm or more and 100 nm or less. For the production of the slice, "Ultramicrotome EM UC7" (Leica Microsystems Co., Ltd.) or the like can be used. Then, the remaining block after the uniform slice without the holes or the like is cut out as a measurement sample. Then, in the cross section obtained by cutting the above-mentioned section of the measurement sample, the Berkovich indenter (triangular cone) as the indenter was pressed into the center of the cross section of the functional layer at 500 nm under the following measurement conditions. After the relaxation of the residual stress is kept constant, the load is unloaded, and the maximum load after the relaxation is measured. Using the maximum load P _max (μN) and the recessed area A (nm ² ) of the depth of 500 nm, the horse is calculated by P _max /A. Hardness. The Martens hardness is an arithmetic mean of the values obtained by measuring 10 sites.

(measurement conditions)

‧Load speed: 10nm/sec

‧ Hold time: 5 seconds

‧ load unloading speed: 10nm / sec

‧Measurement temperature: 25 ° C

Regarding the functional layer 12, the Martens hardness of the center of the cross section of the functional layer 12 is preferably 500 MPa or more and 2000 MPa or less. When the Martens hardness of the functional layer 12 is 500 MPa or more, sufficient hardness as a hard coat layer can be obtained, and if it is 2000 MPa or less, good folding performance of the optical film can be obtained. The lower limit of the Martens hardness of the center of the cross section of the functional layer 12 is preferably 600 MPa or more, and the upper limit is preferably 1500 MPa or less.

The refractive index of the functional layer 12 may be 1.400 or more and 1.800 or less. The refractive index of the functional layer 12 can be measured using a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation), and the average reflectance at a wavelength of 380 to 780 nm is measured, and the obtained average reflectance is used, by the following formula. (2) Find it. The average reflectance of the functional layer 12 is obtained by coating a composition for a functional layer on a polyethylene terephthalate (PET) substrate having a thickness of 50 μm which is not easily processed. It is hardened to form a functional layer having a thickness of 1 to 10 μm, and a black polyvinyl chloride insulating tape having a larger width than the measuring point area is attached to the opposite side (back surface) of the surface of the PET substrate and the functional layer side (for example) The product name "Yamato vinyl tape NO200-38-21", manufactured by Yamato Co., Ltd., width 38 mm) was used to prevent back reflection, and then measurement was performed.

R ₂ =(1-n ₂ ) ² /(1+n ₂ ) ² (2)

In the above formula (2), R ₂ represents an average reflectance (%) of a functional layer having a wavelength of 380 to 780 nm, and n ₂ represents a refractive index of a functional layer.

The film thickness of the functional layer 12 is preferably 2 μm or more and 40 μm or less. When the film thickness of the functional layer 12 is 2 μm or more, sufficient hardness as a hard coat layer can be obtained, and if it is 40 μm or less, deterioration of workability can be suppressed. In the present specification, the "thickness of the functional layer" means a film thickness (total thickness) obtained by summing the film thicknesses of the respective functional layers when the functional layer has a multilayer structure. The upper limit of the functional layer 12 is more preferably 30 μm or less, and still more preferably 20 μm or less.

The film thickness of the functional layer 12 is a cross section of the functional layer 12 taken by a scanning electron microscope (STEM) or a transmission electron microscope (TEM), and the functional layer 12 of 20 parts is measured in the image of the cross section. The film thickness is an arithmetic mean of the film thicknesses of the 20 parts. The method of photographing a specific cross-sectional photograph will be described below. First, a block in which an optical film cut out at a size of 1 mm × 10 mm is embedded in an embedding resin is produced, and a uniform thickness of 70 nm or more and 100 nm is formed from the block by a general slicing method. The following slices. For the production of the slice, "Ultramicrotome EM UC7" (Leica Microsystems Co., Ltd.) or the like can be used. Then, a uniform slice having no pores or the like was used as a measurement sample. Thereafter, a cross-sectional photograph of the measurement sample was taken using a scanning transmission electron microscope (STEM) (product name "S-4800", manufactured by Hitachi High-Technologies Co., Ltd.). When the cross-sectional photograph was taken using the above S-4800, the detector was set to "TE", the acceleration voltage was set to "30 kV", and the emission current was set to "10 μA" to perform cross-sectional observation. Regarding the magnification, while adjusting the focal length and distinguishing or observing the layers with contrast and brightness, it is appropriately adjusted at 5000 times to 200,000 times. The preferred magnification is 10,000 times to 100,000 times, and the preferred magnification is 10,000 times to 50,000 times, and the best magnification is 25,000 times to 50,000 times. Further, when the cross-sectional photograph is taken using the above S-4800, the aperture can be further set to "beam detection aperture 3", the objective aperture can be set to "3", and W.D. can be set to "8 mm". When measuring the film thickness of the hard coat layer, it is important to observe the interface contrast between the functional layer and other layers (for example, a resin substrate) as much as possible when performing cross-sectional observation. When it is difficult to observe the interface due to insufficient contrast, if dyeing treatment such as ruthenium tetroxide, osmium tetroxide or phosphotungstic acid is carried out, the interface between the organic layers can be easily observed, and therefore dyeing treatment can be performed. Moreover, there is a case where the contrast of the interface is more difficult to distinguish at a high magnification. In this case, observation is also performed simultaneously at a low magnification. For example, observation is performed at two magnifications of 25,000 times and 50,000 times, or 50,000 times and 100,000 times, and the arithmetic mean value is obtained at a double rate. Further, the average value is taken as the value of the film thickness of the functional layer.

Since the functional layer 12 is an antistatic hard coat layer, it contains a binder resin and an antistatic agent present in the binder resin. Further, when the functional layer 12 is a hard coat layer having no antistatic property, the antistatic agent may not be contained. Further, the functional layer 12 may contain, for example, particles such as inorganic particles or organic particles, ultraviolet absorbers, adhesion improvers, leveling agents, and thixotropic properties, in addition to the binder resin and the like, as long as the effects of the present invention are not impaired. Additives such as an imparting agent, a coupling agent, a plasticizer, an antifoaming agent, a filler, a colorant, and a filler.

<Binder resin>

The binder resin contains a polymer (cured product) of a polymerizable compound (curable compound). The polymerizable compound is one having at least one polymerizable functional group in the molecule. Examples of the polymerizable functional group include ethylenically unsaturated groups such as a (meth)acryl fluorenyl group, a vinyl group, and an allyl group. In addition, the "(meth)acryl fluorenyl group" has the meaning of both "acryloyl fluorenyl group" and "methacryl fluorenyl group".

As the polymerizable compound, a polyfunctional (meth) acrylate is preferable. Examples of the polyfunctional (meth) acrylate include trimethylolpropane tri(meth)acrylate, tripropylene glycol di(meth)acrylate, and diethylene glycol di(meth)acrylate. Dipropylene glycol di(meth)acrylate, neopentyl alcohol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6 -Hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate , dipentaerythritol penta (meth) acrylate, tripentenol octa (meth) acrylate, tetrapentaerythritol deca (meth) acrylate, iso-cyanuric acid tris(methyl) Acrylate, di(meth) acrylate, polyester tri(meth) acrylate, polyester di(meth) acrylate, bisphenol di(meth) acrylate, diglycerin tetra ( Methyl)acrylate, adamantyl di(meth)acrylate, isodecyl di(meth)acrylate, dicyclopentane di(meth)acrylate, tricyclodecane di(meth)acrylate Di-hydroxyl The base propane tetra(meth)acrylate or the use of PO, EO, caprolactone and the like.

In these, it is preferably from 3 to 6 in terms of the above-mentioned Martens hardness, and for example, preferably pentaerythritol triacrylate (PETA) or dipentaerythritol Acrylate (DPHA), neopentyltetraol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPPA), trimethylolpropane tri(meth)acrylate, tripentaerythritol eight (A) Acrylate, tetrapentaerythritol deca (meth) acrylate, and the like. In the present specification, the term "(meth)acrylate" means "acrylate" and "methacrylate".

Further, in order to adjust the hardness, the viscosity of the composition, the adhesion, and the like, a monofunctional (meth) acrylate monomer may be further contained. Examples of the monofunctional (meth) acrylate monomer include hydroxyethyl acrylate (HEA), glycidyl methacrylate, methoxy polyethylene glycol (meth) acrylate, and (methyl). Isostearyl acrylate, 2-propenyl methoxy succinate, propylene ruthenium, N-propylene methoxyethyl hexahydrophthalimide, cyclohexyl acrylate, tetrahydrofurfuryl acrylate , isodecyl acrylate, phenoxyethyl acrylate, and adamantyl acrylate.

The weight average molecular weight of the above monomer is preferably less than 1,000, more preferably 200 or more and 800 or less from the viewpoint of increasing the hardness of the functional layer. Moreover, the weight average molecular weight of the polymerizable oligomer is preferably 1,000 or more and 20,000 or less, more preferably 1,000 or more and 10,000 or less, and still more preferably 2,000 or more and 7,000 or less.

<antistatic agent>

The antistatic agent used for the functional layer 12 is not particularly limited as long as it has good compatibility with the binder resin. As the antistatic agent, there are an ion-conducting antistatic agent and an electron-conducting antistatic agent, and from the viewpoint of compatibility with the binder resin, an ion-conductive antistatic agent is preferred.

Examples of the ion-conductive antistatic agent include cationic antistatic agents such as quaternary ammonium salts and pyridinium salts, and alkali metal salts (for example, lithium salts, sodium salts, and potassium salts) such as sulfonic acid, phosphoric acid, and carboxylic acid. An amphoteric antistatic agent such as an anionic antistatic agent, an amino acid system or an amino acid sulfate, or a nonionic antistatic agent such as an amino alcohol system, a glycerin system or a polyethylene glycol system. Among these, a quaternary ammonium salt or a lithium salt is preferred in terms of exhibiting excellent compatibility with the binder resin.

Examples of the electron-conducting antistatic agent include conductive particles such as a polyacetylene-based or polythiophene-based conductive polymer, metal particles, and metal oxide particles. Among these, an antistatic agent, metal particles, and metal oxide particles obtained by combining a dopant with a conductive polymer such as polyacetylene or polythiophene are preferable. Further, conductive particles may be contained in the conductive polymer.

Specific examples of the antistatic agent composed of the above conductive polymer include polyacetylene, polyaniline, polythiophene, polypyrrole, polyphenylene sulfide, poly(1,6-heptadiyne), and poly a conductive polymer such as a benzene (polyphenylene terephthalate), a polyparaphenylene sulfide, a polyphenylacetylene, a poly(2,5-thienylthio) group, or a derivative thereof, preferably a polythiophene-based conductive material Organic polymer (for example, 3,4-ethylenedioxythiophene (PEDOT), etc.).

By using an antistatic agent composed of the above conductive organic polymer, the humidity dependency is small, the antistatic property can be maintained for a long period of time, and the transparency is high, the haze is low, and the hard coating is performed. Higher, especially can significantly improve the pencil hardness, scratch resistance of steel wool and the like.

The metal constituting the metal particles is not particularly limited, and examples thereof include a simple substance such as Au, Ag, Cu, Al, Fe, Ni, Pd, or Pt, or an alloy of the metals. Further, the metal oxide constituting the metal oxide particles is not particularly limited, and examples thereof include tin oxide (SnO ₂ ), bismuth oxide (Sb ₂ O ₅ ), antimony doped tin oxide (ATO), and tin-doped oxidation. Indium (ITO), aluminum-doped zinc oxide (AZO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), and the like.

The content of the antistatic agent is not particularly limited, and is preferably 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the polymerizable compound of the functional layer composition. When the amount is 1 part by mass or more, the above-mentioned antistatic property can be sufficiently obtained. When the amount is 50 parts by mass or less, a highly transparent film having a small haze value and a good total light transmittance can be obtained. The lower limit of the content of the antistatic agent is more preferably 10 parts by mass or more, and the upper limit is more preferably 40 parts by mass or less.

The functional layer 12 may further contain an ultraviolet absorber, a spectroscopic transmittance adjuster, and/or an antifouling agent.

<UV absorber>

The optical film can be especially preferably used for a mobile terminal such as a foldable smart phone or a tablet terminal. However, since such a mobile terminal is used outdoors in many cases, there is a polarizing element disposed on the side of the display element of the optical film. The problem of being easily deteriorated by exposure to ultraviolet rays. However, since the functional layer 12 is disposed on the observer side of the polarizing element, if the functional layer 12 contains the ultraviolet absorbing agent, deterioration due to exposure of the polarizing element to ultraviolet rays can be preferably prevented. Further, the ultraviolet absorber (UVA) may be contained in the resin substrate 11 without being contained in the functional layer 12.

As the ultraviolet absorber, for example, three It is a UV absorber, a benzophenone-based UV absorber, and a benzotriazole-based UV absorber.

As the above three The ultraviolet absorber is, for example, 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3 , 5-three ,2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)- 1,3,5-three , 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-three 2-[4-[(2-Hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)- 1,3,5-three And 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl) )-1,3,5-three Wait. As a commercially available three Examples of the ultraviolet absorber include, for example, TINUVIN 460, TINUVIN 477 (both manufactured by BASF Corporation), and LA-46 (manufactured by Adeka Co., Ltd.).

Examples of the benzophenone-based ultraviolet absorber include 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, and 2,2'-dihydroxy-4,4'-dimethoxy. Benzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, hydroxymethoxybenzophenone sulfonic acid and its three Hydrate, sodium hydroxymethoxybenzophenone sulfonate, and the like. As a commercially available benzophenone-based ultraviolet absorber, for example, CHMASSORB81/FL (manufactured by BASF Corporation) or the like can be mentioned.

As the benzotriazole-based ultraviolet absorber, for example, 2-ethylhexyl-3-[3-t-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazole-2) -yl)phenyl]propionate, 2-(2H-benzotriazol-2-yl)-6-(linear and side chain dodecyl)-4-methylphenol, 2-[5- Chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(t-butyl)phenol, 2-(2H-benzotriazol-2-yl)-4,6-di Third amyl phenol, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3,5'-di-t-butylphenyl) benzo Triazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3,5'-di-t-butyl Phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthalimidomethyl)-5 '-Methylphenyl)benzotriazole, 2,2-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2 -yl)phenol) and 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole and the like. Examples of commercially available benzotriazole-based ultraviolet absorbers include KEMISORB71D, KEMISORB79 (all manufactured by Chemipro Kasei Co., Ltd.), JF-80, JAST-500 (all manufactured by Seongbuk Chemical Co., Ltd.), and ULS-1933D (one side). Made by the company), RUVA-93 (manufactured by Otsuka Chemical Co., Ltd.), etc.

In particular, the ultraviolet absorber can preferably use three It is a UV absorber and a benzotriazole UV absorber. The ultraviolet absorber preferably has a high solubility with respect to the resin component constituting the functional layer, and preferably has less bleeding after the continuous folding test. The ultraviolet absorber is preferably polymerized or oligomerized. As the ultraviolet absorber, it is preferred to have benzotriazole, three a polymer or oligomer of a benzophenone skeleton, specifically, preferably a (meth) acrylate having a benzotriazole or benzophenone skeleton and methyl methacrylate (MMA) Any combination of thermal copolymerization. Furthermore, when the optical film is applied to an organic light emitting diode (OLED) display device, the ultraviolet absorber can also function to protect the OLED from ultraviolet rays.

The content of the ultraviolet absorber is not particularly limited, and is preferably 1 part by mass or more and 6 parts by mass or less with respect to 100 parts by mass of the solid content of the functional layer composition. When the amount is 1 part by mass or more, the effect of allowing the ultraviolet absorber to be contained in the functional layer can be sufficiently obtained, and if it is 6 parts by mass or less, no significant coloring or strength reduction occurs in the functional layer. The lower limit of the content of the ultraviolet absorber is more preferably 2 parts by mass or more, and the upper limit is more preferably 5 parts by mass or less.

<Spectral transmittance adjuster>

The spectral transmittance adjusting agent adjusts the spectral transmittance of the optical film. When the functional layer 12 contains, for example, a sesame phenol type benzotriazole-based monomer represented by the following formula (25), the above-described spectral transmittance can be preferably satisfied.

In the formula, R ⁷ represents a hydrogen atom or a methyl group. R ⁸ represents a linear or branched alkyl group having 1 to 6 carbon atoms or a linear or branched oxygen alkyl group having 1 to 6 carbon atoms.

The above-mentioned sesame phenol type benzotriazole-based monomer is not particularly limited, and specific examples of the substance include 2-[2-(6-hydroxybenzo[1,3]dioxoleyl methacrylate. Pentene-5-yl)-2H-benzotriazol-5-yl]ethyl ester, 2-[2-(6-hydroxybenzo[1,3]dioxol-5-yl) acrylate -2H-benzotriazol-5-yl]ethyl ester, 3-[2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzoyl methacrylate Triazol-5-yl]propyl ester, 3-[2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl] Propyl ester, 4-[2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl]butyl methacrylate, acrylic acid 4 -[2-(6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl]butyl acrylate, 2-[2-( 6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yloxy]ethyl ester, 2-[2-(6-hydroxybenzo)acrylate [1,3]dioxol-5-yl)-2H-benzotriazol-5-yloxy]ethyl ester, 2-[3-{2-(6-hydroxybenzo) methacrylate [1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propanyloxy]ethyl ester, 2-[3-{{ 2-(6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propenyloxy]ethyl ester, 4-[methacrylic acid methacrylate 3-{2-(6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propenyloxy]butyl ester, acrylic acid 4- [3-{2-(6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propenyloxy]butyl ester, methyl 2-[3-{2-(6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propanoxy]ethyl acrylate 2-[3-{2-(6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propenyloxy]B Ester, 2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazole-5carboxylic acid 2-(methacryloxy)ethyl ester, 2-(Propyloxy)ethyl 2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazole-5-carboxylate, 4- (Methethyloxy)butyl 2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazole-5-carboxylate, 4- (Propylene methoxy) butyl 2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazole-5-carboxylate. In addition, one type of these sesame phenol type benzotriazole type monomers may be used, or two or more types may be used.

<Antifouling agent>

The antifouling agent is not particularly limited, and examples thereof include a polyfluorene antifouling agent, a fluorine antifouling agent, and a polyfluorinated antifouling agent, which may be used singly or in combination. Further, the antifouling agent may be an acrylic antifouling agent.

The content of the antifouling agent is preferably 0.01 to 3.0 parts by mass based on 100 parts by mass of the polymerizable compound. When it is 0.01 part by mass or more, sufficient antifouling performance can be imparted to the functional layer, and if it is 3.0 parts by mass or less, the hardness of the functional layer is not lowered.

The antifouling agent preferably has a weight average molecular weight of 5,000 or less, and preferably has one or more, more preferably two or more reactive functional groups in order to improve the durability against the antifouling property. Among them, excellent anti-scratch resistance can be imparted by using an antifouling agent having two or more reactive functional groups.

When the antifouling agent does not have a reactive functional group, the antifouling agent may be transferred to the back side of the optical film when it is overlapped, in the case where the optical film is in the form of a roll or in the form of a sheet. If another layer is to be attached or applied to the back surface of the optical film, peeling of the other layers may occur, and further, it may be easily peeled off by performing a plurality of continuous folding tests.

Further, the antifouling performance of the antifouling agent having the reactive functional group is excellent in durability (durability), and the functional layer containing the fluorine-based antifouling agent is less likely to adhere (not conspicuous) to the fingerprint, and the wiping property Also good. Further, since the surface tension at the time of application of the composition for a functional layer can be reduced, the leveling property is good, and the appearance of the formed functional layer becomes good.

The functional layer containing the polyoxyn antifouling agent has good slidability and good steel wool resistance. A touch sensor equipped with an optical film having a functional layer containing such a polyoxygen-based antifouling agent is excellent in sliding when it is brought into contact with a finger or a pen, and thus has a good touch. Moreover, the fingerprint is not easily attached to the functional layer (it is difficult to conspicuous), and the wiping property is also good. Further, since the surface tension at the time of application of the composition for a functional layer can be reduced, the leveling property is good, and the appearance of the formed functional layer becomes good.

For example, SUA1900L10 (manufactured by Shin-Nakamura Chemical Co., Ltd.), SUA1900L6 (manufactured by Shin-Nakamura Chemical Co., Ltd.), Ebecryl 1360 (manufactured by Daicel-Cytec Co., Ltd.), and UT3971 (manufactured by Nippon Synthetic Co., Ltd.) are available as a commercial product of the polyoxo-based antifouling agent. ), BYKUV3500 (manufactured by BYK-Chemie Co., Ltd.), BYKUV3510 (manufactured by BYK-Chemie Co., Ltd.), BYKUV3570 (manufactured by BYK-Chemie Co., Ltd.), X22-164E, X22-174BX, X22-2426, KBM503, KBM5103 (manufactured by Shin-Etsu Chemical Co., Ltd.) TEGO-RAD2250, TEGO-RAD2300, TEGO-RAD2200N, TEGO-RAD2010, TEGO-RAD2500, TEGO-RAD2600, TEGO-RAD2700 (manufactured by Evonik Japan), Megafac RS854 (manufactured by DIC Corporation), and the like.

As a commercial item of the fluorine-based antifouling agent, for example, Optool DAC, Optool DSX (manufactured by Daikin Industries, Ltd.), Megafac RS71, Megafac RS74 (manufactured by DIC Corporation), LINC152EPA, LINC151EPA, LINC182UA (Kyoeisha Chemical Co., Ltd.) Manufacturing), Ftergent 650A, Ftergent 601AD, Ftergent 602, etc.

Commercial products of a fluorine-based and polyoxo-based antifouling agent having a reactive functional group include, for example, Megafac RS851, Megafac RS852, Megafac RS853, Megafac RS854 (manufactured by DIC Corporation), Opstar TU2225, and Opstar TU2224 ( JSR company, X71-1203M (manufactured by Shin-Etsu Chemical Co., Ltd.).

<<1st optical adjustment layer>>

The optical adjustment layer 13 is a layer for suppressing generation of interference fringes. The refractive index of the optical adjustment layer 13 is preferably lower than the refractive index of the resin substrate 11 and higher than the refractive index of the functional layer 12 from the viewpoint of suppressing generation of interference fringes. The refractive index of the optical adjustment layer 13 can be measured by the same method as the refractive index of the above functional layer, and thus the description thereof is omitted here.

The difference in refractive index between the optical adjustment layer 13 and the functional layer 12 (the refractive index of the optical adjustment layer - the refractive index of the functional layer) is preferably 0.005 or more and 0.100 or less. When the refractive index difference is 0.005 or more, the level of the interference fringe is not observed when the interface between the optical adjustment layer 13 and the functional layer 12 is reflected, and if it is 0.100 or less, it is possible to confirm a little interference. Stripe but no problem in actual use. The lower limit of the refractive index difference is more preferably 0.007 or more, and the upper limit is more preferably 0.090 or less. The refractive index of the optical adjustment layer 13 may be 0.010 or more and 0.080 or less.

The film thickness of the optical adjustment layer 13 is preferably 30 nm or more and 200 nm or less. When the thickness of the optical adjustment layer 13 is 30 nm or more, sufficient adhesion between the functional layer 12 and the optical adjustment layer 13 can be ensured, and if it is 200 nm or less, interference fringes can be further suppressed and the foldability can be improved. The film thickness of the optical adjustment layer 13 can be obtained by the same method as the functional layer 12. The lower limit of the optical adjustment layer 13 is more preferably 50 nm or more, and the upper limit is more preferably 150 nm or less.

The optical adjustment layer 13 may be composed only of a resin, and preferably contains a binder resin and particles for adjusting the refractive index. The binder resin of the optical adjustment layer 13 is preferably selected from the group consisting of a (meth)acrylic resin, a cellulose resin, an urethane resin, a vinyl chloride resin, a polyester resin, a polyolefin resin, and a poly At least one resin selected from the group consisting of carbonate, nylon, polystyrene, and ABS resin. The particles of the optical adjustment layer 13 are preferably selected from the group consisting of low refractive index particles such as silica or magnesium fluoride, metal oxide particles such as titanium oxide or zirconium oxide, and inorganic pigments such as cobalt blue. At least one. Among these, from the viewpoint of adjusting the adhesion and the refractive index difference, it is more preferably a combination of a polyester resin and metal oxide particles such as titanium oxide or zirconium oxide.

Further, in order to obtain antistatic properties, the optical adjustment layer 13 may also contain an antistatic agent. When the optical adjustment layer 13 contains an antistatic agent, the optical adjustment layer 13 also functions as an antistatic layer. By including the antistatic agent in the optical adjustment layer 13, the surface resistance value of the front surface 10A of the optical film 10 can be more stabilized. When the optical adjustment layer 13 contains an antistatic agent, if the functional layer 12 also contains an antistatic agent, the surface resistance value of the front surface 10A of the optical film 10 can be further stabilized. The antistatic agent contained in the optical adjustment layer 13 can be the same as the antistatic agent described in the column of the functional layer 12, and thus the description thereof is omitted here.

<<2nd optical adjustment layer>>

The optical adjustment layer 14 is mainly used for a layer which does not cause interference fringes and improves the adhesion between the resin substrate 11 and the optical adjustment layer 13. By providing the optical adjustment layer 14 between the resin substrate 11 and the optical adjustment layer 13, the adhesion can be improved when the resin substrate 11 and the optical adjustment layer 13 are in direct contact with each other.

The refractive index of the optical adjustment layer 14 is preferably lower than the refractive index of the resin substrate 11 and higher than the refractive index of the optical adjustment layer 13 from the viewpoint of interference fringes. The refractive index of the optical adjustment layer 14 can be measured by the same method as the functional layer 12, and thus the description thereof is omitted here.

The difference in refractive index between the optical adjustment layer 14 and the optical adjustment layer 13 (the refractive index of the second optical adjustment layer - the refractive index of the first optical adjustment layer) is preferably 0.005 or more and 0.100 or less. When the refractive index difference is 0.005 or more, the level of the interference fringe is not observed when the interface between the optical adjustment layer 14 and the optical adjustment layer 13 is reflected, and if it is 0.100 or less, it can be confirmed that it is a little Interference fringes but no problem in actual use. The lower limit of the refractive index difference is more preferably 0.007 or more, and the upper limit is more preferably 0.090 or less. The refractive index of the optical adjustment layer 13 may be 0.010 or more and 0.080 or less.

The film thickness of the optical adjustment layer 14 is preferably 30 nm or more and 200 nm or less. When the film thickness of the optical adjustment layer 14 is 30 nm or more, sufficient adhesion between the optical adjustment layer 13 and the optical adjustment layer 14 and the resin substrate 11 and the optical adjustment layer 14 can be ensured, and if it is 200 nm or less, it is not The interference fringes are generated due to the difference in refractive index between the optical adjustment layer 14 and the optical adjustment layer 13, and the folding property can be improved. The film thickness of the optical adjustment layer 14 is obtained by the same method as the functional layer 12. The lower limit of the optical adjustment layer 14 is more preferably 50 nm or more, and the upper limit is more preferably 150 nm or less.

The optical adjustment layer 14 may be composed only of a resin, and preferably contains a binder resin and particles for adjusting the refractive index. The resin of the optical adjustment layer 14 is preferably selected from the group consisting of a (meth)acrylic resin, a cellulose resin, an amine ester resin, a vinyl chloride resin, a polyester resin, a polyolefin resin, a polycarbonate, and a nylon. At least one resin selected from the group consisting of polystyrene and ABS resin. The particles of the optical adjustment layer 13 are preferably at least one selected from the group consisting of low refractive index particles such as ceria or magnesium fluoride, metal oxide particles such as titanium oxide or zirconium oxide, and inorganic pigments such as cobalt blue. . Among these, from the viewpoint of adjusting the adhesion and the refractive index difference, it is more preferably a combination of a polyester resin and metal oxide particles such as titanium oxide or zirconium oxide.

Further, in order to obtain antistatic properties, the optical adjustment layer 14 may also contain an antistatic agent. When the optical adjustment layer 14 contains an antistatic agent, the optical adjustment layer 14 also functions as an antistatic layer. By including the antistatic agent in the optical adjustment layer 14, the surface resistance value of the front surface 10A of the optical film 10 can be more stabilized. When the optical adjustment layer 14 contains an antistatic agent, when the functional layer 12 contains an antistatic agent, the surface resistance value of the front surface 10A of the optical film 10 can be further stabilized. The antistatic agent contained in the optical adjustment layer 14 can be the same as the antistatic agent described in the column of the functional layer 12, and thus the description thereof is omitted here.

<<3rd optical adjustment layer>>

The optical adjustment layer 15 is a layer that increases the light transmittance of the optical film 10. The refractive index of the optical adjustment layer 15 is higher than 1.000 as the refractive index of air, and is lower than the refractive index of the resin substrate 11. The refractive index of the optical adjustment layer 15 can be measured by the same method as the refractive index of the functional layer 12 described above, and thus the description thereof is omitted here.

The difference in refractive index between the resin substrate 11 and the optical adjustment layer 15 (the refractive index of the resin substrate - the refractive index of the third optical adjustment layer) is preferably 0.005 or more and 0.700 or less. When the refractive index difference is 0.005 or more, the light transmittance of the optical film 10 can be increased, and if it is 0.700 or less, the transparency of the optical film 10 is not impaired. The lower limit of the refractive index difference is more preferably 0.010 or more, and the upper limit is more preferably 0.600 or less. The refractive index of the optical adjustment layer 15 may be 0.050 or more and 0.500 or less.

The film thickness of the optical adjustment layer 15 is preferably 30 nm or more and 1 μm or less. When the film thickness of the optical adjustment layer 15 is 30 nm or more, the light transmittance of the optical film 10 can be further increased, and if it is 1 μm or less, deterioration of workability can be suppressed. The film thickness of the optical adjustment layer 15 can be obtained by the same method as the functional layer 12. The lower limit of the optical adjustment layer 15 is more preferably 50 nm or more, and the upper limit is more preferably 700 nm or less, further preferably 500 nm or less.

The configuration of the optical adjustment layer 15 is not particularly limited as long as it is a layer having a refractive index higher than 1.000 and lower than the refractive index of the resin substrate 11 . The optical adjustment layer 15 may be composed of a resin. In addition to the resin, the optical adjustment layer 15 may contain low refractive index particles having a refractive index lower than that of the resin in order to further lower the refractive index. Further, in order to obtain antistatic properties, the optical adjustment layer 15 may also contain an antistatic agent. When the optical adjustment layer 15 contains an antistatic agent, the optical adjustment layer 15 also functions as an antistatic layer. Further, in order to adjust the color tone of the optical film 10, the optical adjustment layer 15 may contain a color tone adjusting agent such as the above-described spectral transmittance adjusting agent.

<Resin>

The resin is preferably selected from the group consisting of (meth)acrylic resins, cellulose resins, amine ester resins, vinyl chloride resins, polyester resins, polyolefin resins, polycarbonates, nylons, polystyrenes, and At least one resin selected from the group consisting of ABS resins. Among these, from the viewpoint of adhesion to the resin substrate 11, a (meth)acrylic resin, an amine ester resin, a polyester resin or the like is preferable.

Examples of the (meth)acrylic resin include polymethyl methacrylate and the like. In addition, examples of the cellulose resin include diethylacetone cellulose, cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB). Examples of the amine ester-based resin include an amine ester resin and the like.

Examples of the vinyl chloride-based resin include polyvinyl chloride, a vinyl chloride-vinyl acetate copolymer, and the like. Moreover, as the polyester-based resin, for example, polyethylene terephthalate or the like can be mentioned. Further, examples of the polyolefin-based resin include polyethylene and polypropylene.

<low refractive index particles>

Examples of the low refractive index particles include solid or hollow particles composed of cerium oxide or magnesium fluoride. Among these, hollow cerium oxide particles are preferable, and such hollow cerium oxide particles can be produced, for example, by the production method described in the examples of JP-A-2005-099778.

The average particle diameter (average primary particle diameter) of the low refractive index particles is preferably 5 nm or more and 100 nm or less. When the average particle diameter of the low refractive index particles is within the above range, the transparency of the optical adjustment layer 15 is not impaired, and a dispersed state of good particles can be obtained. The average particle diameter of the low refractive index particles is determined by measuring the image of the cross section of the optical adjustment layer 15 taken by a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM). The arithmetic mean of the particle sizes of the 20 low refractive index particles is used. The lower limit of the average particle diameter of the low refractive index particles is more preferably 10 nm or more, and the upper limit is more preferably 80 nm or less, further preferably 70 nm or less.

As the low refractive index particles, cerium oxide particles (reactive cerium oxide particles) having a reactive group on the surface are preferably used, and reactive hollow cerium oxide particles are particularly preferable. Such cerium oxide particles having a reactive group on the surface can be produced by surface-treating cerium oxide particles with a decane coupling agent or the like. The method of treating the surface of the cerium oxide particles with a decane coupling agent may be a dry method in which a cerium coupling agent is sprayed on a cerium oxide particle, or a decane coupling agent may be added after dispersing the cerium oxide particles in a solvent. The wet method of reaction, etc.

<antistatic agent>

The antistatic agent contained in the optical adjustment layer 15 can be the same as the antistatic agent described in the column of the functional layer 12, and thus the description thereof is omitted here.

<<Method of manufacturing optical film>>

The optical film 10 can be produced, for example, in the following manner. First, a second optical adjustment layer composition for forming the optical adjustment layer 14 is applied onto the first surface 11A of the resin substrate 11 by a coating device such as a bar coater to form a second optical adjustment. The coating film of the composition for the layer.

<Composition for second optical adjustment layer>

The composition for the second optical adjustment layer contains particles such as a binder resin precursor and a metal oxide, and a solvent. The term "adhesive resin precursor" as used herein refers to a component which is a binder resin by removing a solvent or hardening it by heat or ionizing radiation.

Examples of the binder resin precursor include a solvent-drying resin and a polymerizable compound which is cured by heat or ionizing radiation. Examples of the ionizing radiation in the present specification include visible light rays, ultraviolet rays, X-rays, electron beams, α rays, β rays, and γ rays. The composition for the second optical adjustment layer may further contain at least one of low refractive index particles such as cerium oxide or magnesium fluoride, an inorganic pigment such as cobalt blue, a leveling agent, and a polymerization initiator. In the case where a polyester resin is used as the binder resin precursor, the second optical adjustment layer composition may optionally contain a (meth)acrylic resin, a cellulose resin, or an amine ester resin. One or more resins selected from the group consisting of vinyl chloride resin, polyolefin resin, polycarbonate, nylon, polystyrene, and ABS resin.

After the coating film of the composition for the second optical adjustment layer is formed, the coating film is dried by heating at a temperature of, for example, 40 ° C or higher and 200 ° C or lower for 10 seconds to 120 seconds by various known methods to evaporate the solvent. Further, the coating film is cured, and the coating film is irradiated with ionizing radiation such as ultraviolet rays as necessary to form an optical adjustment layer 14 adjacent to the resin substrate 11.

Then, the first optical adjustment layer composition for forming the optical adjustment layer 13 is applied onto the optical adjustment layer 14 by a coating device such as a bar coater to form a composition for the first optical adjustment layer. Coating film.

<Composition for the first optical adjustment layer>

The composition for the first optical adjustment layer contains particles such as a binder resin precursor and a metal oxide, and a solvent. The composition for the first optical adjustment layer may further contain at least one of low refractive index particles such as cerium oxide or magnesium fluoride, an inorganic pigment such as cobalt blue, a leveling agent, and a polymerization initiator. In the case where a polyester resin is used as the binder resin precursor, the first optical adjustment layer composition may optionally contain a (meth)acrylic resin, a cellulose resin, or an amine ester resin. One or more resins selected from the group consisting of vinyl chloride resin, polyolefin resin, polycarbonate, nylon, polystyrene, and ABS resin.

After the coating film of the composition for the first optical adjustment layer is formed, the coating film is dried by heating at a temperature of, for example, 40 ° C or higher and 200 ° C or lower for 10 seconds to 120 seconds by various known methods to evaporate the solvent. Further, the coating film is cured, and the coating film is irradiated with ionizing radiation such as ultraviolet rays as necessary to form the optical adjustment layer 13.

After the optical adjustment layer 13 is formed, a coating layer for forming the functional layer 12 is formed on the optical adjustment layer 13 by a coating device such as a bar coater to form a coating film for the functional layer composition. .

<Composition layer composition>

The functional layer composition contains a polymerizable compound which becomes a binder resin after curing. The functional layer composition may further contain an antistatic agent, an ultraviolet absorber, a spectroscopic transmittance adjuster, an antifouling agent, an inorganic particle, a leveling agent, a solvent, and a polymerization initiator as needed.

(solvent)

Examples of the solvent include alcohols (e.g., methanol, ethanol, propanol, isopropanol, n-butanol, second butanol, third butanol, benzyl alcohol, PGME, ethylene glycol, diacetone alcohol), and ketone. (eg acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, heptanone, diisobutyl ketone, diethyl ketone, diacetone alcohol), ester (methyl acetate, Ethyl acetate, butyl acetate, n-propyl acetate, isopropyl acetate, methyl formate, PGMEA), aliphatic hydrocarbons (eg hexane, cyclohexane), halogenated hydrocarbons (eg dichloromethane, chloroform, tetra Carbon chloride), aromatic hydrocarbons (such as benzene, toluene, xylene), decylamine (such as dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ether (such as diethyl ether, two Alkane, tetrahydrofuran), ether alcohol (for example, 1-methoxy-2-propanol), carbonate (dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate) and the like. These solvents may be used singly or in combination of two or more. In particular, as the solvent, a component such as (meth)acrylic acid amide or the like and other additives are dissolved or dispersed, and a functional layer composition is preferably applied. Methyl isobutyl ketone and methyl are preferred. Ketoethyl ketone.

(polymerization initiator)

The polymerization initiator is a component which decomposes under irradiation with ionizing radiation to generate a radical and initiates or proceeds polymerization (crosslinking) of the polymerizable compound.

The polymerization initiator is not particularly limited as long as it can emit a radical polymerization by irradiation with ionizing radiation. The polymerization initiator is not particularly limited, and a known one can be used. Specific examples thereof include acetophenones, benzophenones, mischalbenzamide benzoate, and α-pentyl hydrazine. Ester, 9-oxosulfur Classes, propiophenones, benzoin, benzoin, fluorenylphosphine oxides. Further, it is preferably used by mixing a photosensitizer, and specific examples thereof include n-butylamine, triethylamine, and poly-n-butylphosphine.

After the coating film of the composition for a functional layer is formed, the coating film is dried by heating at a temperature of, for example, 30 ° C or higher and 120 ° C or lower for 10 seconds to 120 seconds by various known methods to evaporate the solvent.

After drying the coating film, the coating film is irradiated with ionizing radiation such as ultraviolet rays to cure the coating film. Thereby, the functional layer 12 adjacent to the optical adjustment layer 13 is formed.

After forming the functional layer 12, the third optical adjustment layer composition for forming the optical adjustment layer 15 is applied onto the second surface 11B of the resin substrate 11 by a coating device such as a bar coater. A coating film of the composition for the third optical adjustment layer is formed.

<The composition for the third optical adjustment layer>

The composition for the third optical adjustment layer contains a resin precursor and a solvent. The composition for the third optical adjustment layer may optionally contain at least one of a low refractive index particle, an antistatic agent, an inorganic pigment such as cobalt blue, a leveling agent, and a polymerization initiator. In the case where a polyester resin is used as the resin precursor, the third optical adjustment layer composition may optionally contain a (meth)acrylic resin, a cellulose resin, an amine ester resin, and chlorine. One or more resins selected from the group consisting of ethylene resin, polyolefin resin, polycarbonate, nylon, polystyrene, and ABS resin. The solvent is the same as the solvent described in the column for the functional layer composition, and thus the description thereof is omitted here.

After the coating film of the composition for the third optical adjustment layer is formed, the coating film is dried by heating at a temperature of, for example, 40 ° C or higher and 200 ° C or lower for 10 seconds to 120 seconds by various known methods to evaporate the solvent. Further, the coating film is cured, and the coating film is irradiated with ionizing radiation such as ultraviolet rays as necessary to form the optical adjustment layer 15. Thereby, the optical film 10 shown in FIG. 1 was obtained.

<<<Other optical film>>

The optical film may also be the optical films 30, 40, 50, 60 shown in FIGS. 4 to 7. The optical films 30, 40, 50, 60 shown in Figures 4 to 7 are also used for image display devices and are foldable.

The optical film 30 shown in FIG. 4 includes a resin substrate 11 , a functional layer 12 provided on the first surface 11A side of the resin substrate 11 , and an optical adjustment layer 13 provided on the resin substrate 11 and the functional layer 12 . Between and adjacent to the functional layer 12. Further, the optical film 30 shown in FIG. 4 is not provided with the optical adjustment layer 14, and the optical adjustment layer 13 is adjacent to the functional layer 12 and the resin substrate 11. The physical properties and the like of the optical film 30 are the same as those of the optical film 10, and thus the description thereof is omitted here. The front surface 30A of the optical film 30 serves as the front surface 12A of the functional layer 12, and the back surface 30B of the optical film 30 serves as the surface 15A of the optical adjustment layer 15 opposite to the surface on the resin substrate 11 side.

The optical film 40 shown in FIG. 5 includes a resin substrate 11 , a functional layer 12 provided on the first surface 11A side of the resin substrate 11 , and an optical adjustment layer 13 provided on the resin substrate 11 and the functional layer 12 . The resin layer 41 is adjacent to the functional layer 12 and the resin layer 41 is provided on the second surface 11B of the resin substrate 11. Further, the optical film 40 shown in FIG. 5 is not provided with the optical adjustment layer 14, and the optical adjustment layer 13 is adjacent to the functional layer 12 and the resin substrate 11. The front surface 40A of the optical film 40 serves as the front surface 12A of the functional layer 12, and the back surface 30B of the optical film 40 serves as the surface 41A opposite to the surface of the resin layer 41 on the side of the resin substrate 11.

The optical film 50 shown in FIG. 6 includes a resin substrate 11 , a functional layer 12 provided on the first surface 11A side of the resin substrate 11 , and an optical adjustment layer 13 provided on the resin substrate 11 and the functional layer 12 . And adjacent to the functional layer 12; the resin layer 41 is provided on the second surface 11B side of the resin substrate 11, and the optical adjustment layer 15 is provided between the resin substrate 11 and the resin layer 41, and is adjacent to Resin substrate 11. Further, the optical film 50 shown in FIG. 6 is not provided with the optical adjustment layer 14, and the optical adjustment layer 13 is adjacent to the functional layer 12 and the resin substrate 11. The front surface 50A of the optical film 50 serves as the front surface 12A of the functional layer 12, and the back surface 50B of the optical film 50 serves as the surface 41A of the resin layer 41 opposite to the surface on the resin substrate 11 side.

The optical film 60 shown in FIG. 7 includes a resin substrate 11 , a functional layer 12 provided on the first surface 11A side of the resin substrate 11 , and an optical adjustment layer 13 provided on the resin substrate 11 and the functional layer 12 . And adjacent to the functional layer 12; the optical adjustment layer 14 is disposed between the resin substrate 11 and the optical adjustment layer 13 and adjacent to the resin substrate 11, and the resin layer 41 is disposed on the resin substrate 11 The two-sided 11B side and the optical adjustment layer 15 are provided between the resin substrate 11 and the resin layer 41 and are adjacent to the resin substrate 11. Further, the front surface 60A of the optical film 60 serves as the front surface 12A of the functional layer 12, and the back surface 60B of the optical film 60 serves as the surface 41A opposite to the surface of the resin layer 41 on the side of the resin substrate 11.

In the optical films 40, 50, and 60, the shear storage modulus G' at 25 ° C and in the frequency region of 500 Hz or more and 1000 Hz or less exceeds 200 MPa and is 1200 MPa or less. When the shear storage modulus G' of the film exceeds 200 MPa, when an impact is applied to the front surface of the optical film, not only the deformation of the optical film itself but also the optical film is disposed inside the image display device. In the case of the adhesive layer, the plastic deformation of the adhesive layer can also be suppressed. Moreover, when the shear storage modulus G' of the optical films 40, 50, and 60 is 1200 MPa or less, the crack of the optical film 40 at the time of folding can be suppressed. The lower limit of the shear storage modulus G' of the optical films 40, 50, and 60 is preferably 400 MPa or more, and more preferably 500 MPa or more. By setting it as such a lower limit, more excellent impact resistance can be obtained. The upper limit of the shear storage modulus G' of the optical films 40, 50, 60 is preferably less than 800 MPa. By setting such an upper limit, good recovery can be obtained when the folding is allowed to stand and is opened again.

In the optical films 40, 50, and 60, the shear loss modulus G" in the frequency region of 500 Hz or more and 1000 Hz or less at 25 ° C is 3 MPa or more and 150 MPa or less. If the shear loss modulus G" of the optical film is When the pressure is 3 MPa or more, the decrease in impact absorption performance can be suppressed. When the shear loss modulus G" of the optical films 40, 50, and 60 is 150 MPa or less, the hardness of the resin layer 41 can be suppressed from decreasing. The lower limit of the shear loss modulus G" of the optical film 40 is preferably 20 MPa. In addition, the upper limit of the shear loss modulus G" of the optical film 40 is preferably 130 MPa or less, and more preferably 100 MPa or less from the viewpoint of the reduction in thickness of the optical films 40, 50, and 60.

The shear storage modulus G' and the shear loss modulus G" can be measured by a dynamic viscoelasticity measuring device (DMA). The shear storage modulus of the optical film 40 is measured by a dynamic viscoelasticity measuring device (DMA). In the case of G' and the shear loss modulus G", first, the optical film 40 was punched out into a rectangular shape of 10 mm × 5 mm to obtain a sample. Then, two samples of the sample were prepared and attached to a solid-shearing jig which is an option of a dynamic viscoelasticity measuring device (product name "Rheogel-E4000", manufactured by UBM Co., Ltd.). Specifically, as shown in FIG. 8 , the solid shearing jig 70 includes a single metal solid shearing plate (middle plate) having a thickness of 1 mm and two L-shaped metals disposed on both sides of the solid shearing plate 71 . a piece 72 (outer plate), a sample is sandwiched between the solid shearing plate 71 and an L-shaped metal piece 72, and another sample is sandwiched between the solid shearing plate 71 and the other L-shaped metal piece 72. . In this case, the sample S is sandwiched so that the resin layer becomes the solid shearing plate 51 side and the functional layer becomes the L-shaped metal member 72 side. Then, the L-shaped metal members 72 are fastened by screws 53 to fix the sample S. Then, after the tensile test collet composed of the upper chuck and the lower chuck is attached to the dynamic viscoelasticity measuring device (product name "Rheogel-E4000", manufactured by UBM Co., Ltd.), the upper chuck and the lower portion are attached. A solid shearing jig was installed between the chucks at a distance of 20 mm between the chucks. The distance between the chucks is the distance between the upper and lower chucks. Then, the set temperature was set to 25 ° C and the temperature was raised at 2 ° C / min. In this state, the solid-state shearing plate 71 is applied to the two L-shaped metal members 72 to apply a vertical strain of 1% of the strain amount and a frequency of 500 Hz or more and 1000 Hz or less, and the dynamic viscosity of the solid at 25 ° C is performed. For the elastic measurement, the shear storage modulus G' and the shear loss modulus G" of the optical films 40, 50, and 60 are measured. Here, the shear storage modulus G of the optical film in the frequency region of 500 Hz or more and 1000 Hz or less 'and the shear loss modulus G' is a value obtained by applying longitudinal vibrations of frequencies of 500 Hz, 750 Hz, and 950 Hz to the L-shaped metal members, and measuring the shear storage of the optical film at each frequency. The modulus G′ and the shear loss modulus G′′ are obtained, and the arithmetic mean of the shear storage modulus G′ and the shear loss modulus G′ is obtained, and the measurement is repeated three times, and the obtained three are respectively obtained. The arithmetic mean is further arithmetically averaged. Further, in the above, the frequency region of 500 Hz or more and 1000 Hz or less is used because the frequency of the frequency region is such that the front surface of the optical film is deformed by several micrometers to several tens of micrometers when the object is free to fall from a height of several cm. And the frequency of damage to the display panel or the like which exists in the interior of the image display device with respect to the optical film.

The physical properties of the optical films 40, 50, and 60 are the same as those of the optical film 10 except for the above, and thus the description thereof will be omitted.

<<Resin layer>>

The resin layer 41 is a layer composed of a resin having light transmissivity. The resin layer 41 is a layer having impact absorption. The resin layer may have a multilayer structure composed of two or more resin layers.

The film thickness of the resin layer 41 is 50 μm or more and 300 μm or less. When the film thickness of the resin layer 41 is 50 μm or more, the hardness of the resin layer 41 can be suppressed from being lowered, and if it is 300 μm or less, the thickness can be reduced, and the workability is not deteriorated. The film thickness of the resin layer 41 is a cross section of the resin layer 41 by a scanning electron microscope (SEM), and the film thickness of the resin layer 41 at 20 locations is measured in the image of the cross section, and the film thickness of the 20 portions is calculated. average value. The lower limit of the resin layer 41 is more preferably 60 μm or more, and the upper limit of the resin layer 41 is more preferably 150 μm or less, and further preferably 100 μm or less.

The resin constituting the resin layer 41 is a resin in which the shear storage modulus G' and the shear loss modulus G" in the frequency region of the optical film 40 at 25 ° C and 500 Hz or more and 1000 Hz or less are within the above range. The resin is not particularly limited, and examples thereof include an acrylic gel, an amine ester gel, a polyoxygen gel, an amine ester resin, and an epoxy resin. Among these, it is preferably Acrylic gel. The term "gel" generally refers to a dispersion system that loses fluidity at high viscosity. Further, the resin layer 41 may contain a rubber or a thermoplastic elastomer in addition to an acrylic gel or an amine ester resin.

(acrylic gel)

The acrylic gel can be used as long as it is a polymer obtained by polymerizing a monomer containing an acrylate for an adhesive or the like. Specifically, as the acrylic gel, for example, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, ( Isobutyl methacrylate, 2-ethylhexyl (meth) acrylate, n-hexyl (meth) acrylate, n-pentyl (meth) acrylate, isoamyl (meth) acrylate, (methyl) Octyl acrylate, isooctyl (meth)acrylate, isomyristyl (meth)acrylate, lauryl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, (A) Polymerized or copolymerized with an acrylic monomer such as isodecyl acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate or isostearyl (meth) acrylate. In the present specification, the term "(meth)acrylate" means both "acrylate" and "methacrylate". Further, the acrylate to be used in the above (co)polymerization may be used alone or in combination of two or more.

(amine ester resin)

The amine ester resin is a resin having an amine ester bond. The amine ester-based resin may, for example, be a cured product of an ionizing radiation curable amine ester resin composition or a cured product of a thermosetting amine ester resin composition. Among these, a cured product of an ionizing radiation curable amine ester-based resin composition is preferred because it has high hardness and a high curing rate and excellent mass productivity.

The ionizing radiation curable amine ester resin composition contains (meth)acrylic acid amide, and the thermosetting amine ester resin contains a polyol compound and an isocyanate compound. The (meth)acrylic acid amide, the polyol compound, and the isocyanate compound may be any of a monomer, an oligomer, and a prepolymer.

The number (functional group number) of the (meth) acrylonitrile group in the (meth) acrylate is preferably 2 or more and 4 or less. When the amount of the (meth)acrylonitrile group in the (meth)acrylic acid amide is less than 2, the pencil hardness is lowered, and if it exceeds 4, the curing shrinkage is large, and the optical film is curled. Further, cracks are generated in the resin layer during bending. The upper limit of the amount of the (meth) acrylonitrile group in the (meth) acrylate is more preferably 3 or less. In addition, the term "(meth)acrylonitrile" includes both "acryloyl" and "methacryl".

The weight average molecular weight of the (meth) acrylate is preferably 1,500 or more and 20,000 or less. When the weight average molecular weight of the (meth) acrylate is less than 1,500, the impact resistance is lowered, and if it exceeds 20,000, the viscosity of the ionizing radiation curable amine ester resin composition increases, and the coating property is improved. Deterioration. The lower limit of the weight average molecular weight of the (meth) acrylate is more preferably 2,000 or more, and the upper limit is more preferably 15,000 or less.

In addition, examples of the repeating unit having a structure derived from (meth)acrylic acid amide include a structure represented by the following formula (26), (27), (28) or (29).

In the above formula (26), R ⁹ represents a branched alkyl group, R ¹⁰ represents a branched alkyl group or a saturated cyclic aliphatic group, R ¹¹ represents a hydrogen atom or a methyl group, and R ¹² represents a hydrogen atom or a methyl group. Or ethyl, m represents an integer of 0 or more, and x represents an integer of 0-3.

In the above formula (27), R ⁹ represents a branched alkyl group, R ¹⁰ represents a branched alkyl group or a saturated cyclic aliphatic group, R ¹¹ represents a hydrogen atom or a methyl group, and R ¹² represents a hydrogen atom or a methyl group. Or an ethyl group, n represents an integer of 1 or more, and x represents an integer of 0 to 3.

In the above formula (28), R ⁹ represents a branched alkyl group, R ¹⁰ represents a branched alkyl group or a saturated cyclic aliphatic group, R ¹¹ represents a hydrogen atom or a methyl group, and R ¹² represents a hydrogen atom or a methyl group. Or ethyl, m represents an integer of 0 or more, and x represents an integer of 0-3.

In the general formula (29), R ⁹ represents a branched chain alkyl group, R ¹⁰ represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ¹¹ represents a hydrogen atom or a methyl group, R ¹² represents a hydrogen atom, a methyl group Or an ethyl group, n represents an integer of 1 or more, and x represents an integer of 0 to 3.

Further, the polymer chain (repetition unit) of the structure in which the resin constituting the resin layer 41 is formed can be determined, for example, by analyzing the resin layer 41 by thermal decomposition GC-MS and FT-IR. In particular, the thermal decomposition GC-MS is useful because it can detect the monomer unit contained in the resin layer 41 as a monomer component.

Regarding the resin layer 41, as long as the shear storage modulus G' and the shear loss modulus G" of the optical films 40, 50, 60 at 25 ° C and in the frequency region of 500 Hz or more and 1000 Hz or less are within the above range, The ultraviolet absorber, the spectroscopic transmittance adjuster, the antifouling agent, the inorganic particles, and/or the organic particles may be contained. The ultraviolet absorber or the like may be the same as the ultraviolet absorber described in the column of the functional layer 12, and therefore Description is omitted here.

<<<Image Display Device>>

The optical films 10, 30, 40, 50, 60 can be incorporated into a collapsible image display device for use. Fig. 9 is a schematic configuration diagram of a video display device of the embodiment. As shown in FIG. 9, the image display device 80 is mainly provided with a casing 81 for accommodating a battery or the like, a protective film 82, a display element 83, a circularly polarizing plate 84, a touch sensor 85, and an optical film. 10. An adhesive layer 86 having a light transmissive property is disposed between the display element 83 and the circular polarizing plate 84, between the circular polarizing plate 84 and the touch sensor 85, and between the touch sensor 85 and the optical film 10. The members are fixed to each other by the adhesive layer 86. Furthermore, the adhesive layer 86 is disposed between the display element 83 and the circular polarizing plate 84, between the circular polarizing plate 84 and the touch sensor 85, between the touch sensor 85 and the optical film 10, but the adhesive layer The arrangement portion is not particularly limited as long as it is between the optical film and the display element.

The optical film 10 is disposed such that the functional layer 12 is closer to the viewer than the resin substrate 11. In the image display device 80, the front surface 10A of the optical film 10 (the front surface 12A of the functional layer 12) constitutes the front surface 80A of the image display device 80.

In the video display device 80, the display element 83 is an organic light emitting diode element including an organic light emitting diode or the like. The touch sensor 85 is disposed on the observer side of the circular polarizing plate 84, but may be disposed between the display element 83 and the circular polarizing plate 84. Moreover, the touch sensor 85 can also be in a surface-embedded manner or an in-line manner. As the adhesive layer 86, for example, OCA (Optical Clear Adhesive) can be used.

According to the present embodiment, one or more resins selected from the group consisting of a polyimine-based resin, a polyamidamine-based resin, a polyamide resin, and a polyester resin are used. The resin substrate 11 is provided with an optical adjustment layer 13 adjacent to the functional layer 12 between the resin substrate 11 and the functional layer 12, so that it can be folded and the generation of interference fringes can be suppressed.

When the back surface of the optical film is a resin substrate, since the resin substrate is in contact with the air layer, the reflection at the interface between the resin substrate and the air layer is increased, whereby the light transmittance is lowered. In particular, a resin group composed of one or more resins selected from the group consisting of a polyimine-based resin, a polyamidamine-based resin, a polyamide resin, and a polyester resin is used. When the material is used as a resin substrate, since the refractive index of the resin substrate is relatively high, interface reflection is likely to occur. On the other hand, in the second embodiment of the resin substrate 11, the optical adjustment layer 15 having a refractive index higher than 1.000 and lower than the refractive index of the resin substrate 11 is provided on the second surface 11B of the resin substrate 11, so that the resin substrate and the resin substrate are When the air layer is in contact, the interface reflection can be reduced, and the light reflectance can be reduced. Thereby, the light transmittance of the optical films 10 and 30 can be improved.

Further, when the optical adjustment layer 15 contains an antistatic agent, the optical films 10, 30, 50, and 60 have the functional layer 12 as an antistatic hard coat layer on the first surface 11A side of the resin substrate 11, in the resin. Since the optical adjustment layer 15 containing an antistatic agent is provided on the second surface 11B side of the substrate 11, it is possible to suppress adhesion of dust or the like to the optical films 10, 30, 50, and 60. Further, in this case, even if a protective film (not shown) is attached to both surfaces of the optical films 10, 30, 50, and 60, even if the protective film is peeled off from the optical films 10, 30, 50, and 60, The charging of the optical films 10, 30, 50, 60 can also be suppressed. Thereby, the yield of the assembly step of the image display device can be improved.

In the case of an optical film used for a foldable image display device, since impact is applied to the front surface of the optical film, impact resistance is required. Here, when an impact is applied to the front surface of the optical film, there is a case where the front surface of the optical film is recessed, and a display panel (for example, an organic light-emitting diode panel) which is present inside the optical film in the image display device. And other components are damaged. Regarding the depression of the front surface of the optical film, there are recesses generated by the optical film itself and depressions caused by a soft layer such as an adhesive layer disposed inside the image display device. The "depression generated by the optical film itself" refers to a depression caused by the impact of the optical film itself when an impact is applied to the front surface of the optical film, and the "depression caused by the soft layer" It is meant that since the layer is soft, the soft layer disposed inside the image display device is plastically deformed when an impact is applied to the front surface of the optical film, and the optical film follows the plastic deformation of the soft layer, thereby causing the depression. . Therefore, in the optical film, it is preferable to suppress the depression generated by the optical film itself and the depression generated by the soft layer when an impact is applied to the front surface of the optical film, and it is possible to obtain a film which is present in the optical film. The components inside the image display device are excellent in impact resistance without damage. Here, as an index indicating the impact absorption performance, a shear loss tangent tan δ has been previously known. Therefore, the shear loss tangent tan δ is also considered to have the impact resistance of the optical film having the functional layer on the first surface side of the resin substrate and the resin layer on the second surface side, but the shear loss tangent tan δ, When an impact is applied to the front surface of the optical film (the surface of the functional layer), it is impossible to suppress the depression of the surface of the optical film produced by the optical film itself, the depression of the front surface of the optical film produced by the soft layer, and the presence of the optical film. The damage of the components inside the device is shown by the image. The reason is considered to be that the shear loss tangent tan δ is the ratio of the shear loss modulus G" to the shear storage modulus G' (G"/G'). The inventors of the present invention have repeatedly conducted intensive studies, and as a result, found that in order to suppress the application of an impact to the front surface of the optical film, the surface depression caused by the optical film itself and the surface depression caused by the soft layer are more dependent on the optical film. The damage of the members inside the image display device is mainly the balance between the film thickness of the resin layer, the shear storage modulus G', and the shear loss modulus G". According to the present embodiment, it is the first in the resin substrate 11. In the optical films 40, 50, and 60 having the functional layer 12 on the surface 11A side and having the resin layer 41 on the second surface 11B side, the thickness of the resin layer 41 is reduced to 50 μm or more and 300 μm or less, and the optical film 40 is as described above. The shear storage modulus G' exceeds 200 MPa and is 1200 MPa or less, and the shear loss modulus G" of the optical film 40 becomes 3 MPa or more and 150 MPa or less, so that it can be folded and impact is applied to the front surface 40A of the optical film 40. In this case, the depressions of the front faces 40A, 50A, 60A produced by the optical films 40, 50, 60 themselves and the optical films produced by the soft layers existing in the optical film 40, 50, 60 and further inside the image display device can be suppressed. 40, 50, 60 front 40A The depressions of 50A and 60A can suppress damage of members such as the display member 83 located inside the image display device. Thereby, excellent impact resistance can be obtained.

[Second Embodiment]

Hereinafter, an optical film and a video display device according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 10 is a schematic configuration diagram of an optical film of the embodiment, Fig. 11 is a schematic configuration diagram of another optical film of the embodiment, and Fig. 12 is a schematic configuration diagram of the image display device of the embodiment.

<<<Optical film>>>

The optical film 90 shown in Fig. 10 is used for an image display device and can be folded.

The optical film 90 includes a light-transmitting substrate 91 and a first antistatic layer 92 (hereinafter sometimes simply referred to as an antistatic layer 92), which is provided on the first surface 91A side which is one surface of the light-transmitting substrate 91; The second antistatic layer 93 (hereinafter sometimes referred to simply as the antistatic layer 93) is provided on the side of the second surface 91B which is the surface opposite to the first surface 91A of the light-transmitting substrate 91. Further, at least one of the light-transmitting substrate 91 and the antistatic layer 92 and between the light-transmitting substrate 91 and the antistatic layer 93 may be provided with a functional layer.

A protective film may be attached to the surface of the antistatic layers 92 and 93 on the opposite side to the surface on the side of the light-transmitting substrate 91. However, since the protective film is peeled off during use, the protective film is not considered to constitute a part of the optical film. In addition, the physical property value of the optical film 90 in this specification is a value in the state in which the protective film is not provided.

In FIG. 10, the front surface 90A of the optical film 90 becomes the front surface 92A of the antistatic layer 92. The back surface 90B of the optical film 90 serves as a surface 93A of the antistatic layer 93 opposite to the surface on the side of the light-transmitting substrate 91.

The optical film 90 can be folded, and specifically, it is preferable that the optical film 90 does not crack or break even when the optical film 90 is repeatedly subjected to a folding test (continuous folding test) described 100,000 times. More preferably, even if the continuous folding test is repeated 200,000 times, the optical film 90 does not crack or break, and it is preferable that the optical film 90 is not formed even if it is repeated one million times. Produces cracks or breaks. When the optical film 90 is subjected to a continuous folding test for 100,000 times, if the optical film 90 is cracked or the like, the folding property of the optical film 90 is insufficient. The continuous folding test may be performed by folding the optical film 90 such that the antistatic layer 92 is inside, or may be performed by folding the optical film 90 such that the antistatic layer 92 is outside, preferably in either case. None of the optical films are cracked or broken. The continuous folding test was carried out in the same manner as in the first embodiment. However, in the continuous folding test of the present embodiment, the interval between the side portions was set to 3 mm.

The optical film 90 was subjected to a folding and standing test at 70 ° C for 240 hours in the same manner as in the first embodiment, and then the folded state was released, and the optical film 90 was measured for opening after 30 minutes at room temperature. In the case of the angle θ, the opening angle θ of the optical film 90 is preferably 100° or more. The folding and standing test may be performed by folding the optical film 90 such that the antistatic layer 92 is inside, or may be performed by folding the optical film 90 such that the antistatic layer 92 is outside, preferably in any case. When the opening angle θ is 100° or more.

The surface resistance of the front surface 90A and the back surface 90B of the optical film 90 is preferably 10 ¹² Ω/□ or less. The surface resistance value is measured by the same method as the method described in the first embodiment.

Regarding the front surface 90A of the optical film 90 (front surface 92A of the antistatic layer 92), the hardness (pencil hardness) measured by a pencil hardness test prescribed by JIS K5600-5-4:1999 is preferably F or more, more preferably 2H or more. The pencil hardness test was carried out by the same method as the method described in the first embodiment.

In the optical film 90, for the same reason as described in the first embodiment, it is preferable to apply a distance of 50 mm from the front surface 90A of the optical film 90 in an environment of 23 ° C and a relative humidity of 50%. The saturation band voltage of the front surface 90A of the optical film 90 at a voltage of 10 kV exceeds 0 kV. The saturation band voltage is measured by the same method as the method described in the first embodiment. The lower limit of the absolute value of the saturation band voltage is preferably 0.1 kV or more, and the upper limit of the absolute value of the saturation band voltage is preferably 1.0 kV or less.

The optical film 90 preferably has a yellow index (YI) of 15 or less for the same reason as described in the first embodiment. The yellow index is measured by the same method as the method described in the first embodiment. The upper limit of the yellow index (YI) of the optical film 90 is preferably less than 10, and most preferably less than 1.5.

The antistatic layer 93 side faces the optical film 90, and has a continuous spectrum of light irradiated at a wavelength of 300 nm or more and 780 nm or less at an incident angle of 0°, and L ^* a of light (penetrating light) penetrating the optical film 90 is obtained ^{. *} b ^* color coordinates a ^* and b ^* of the color system. In this case, it is preferable that a ^* is -5 or more and +5 or less, and b ^* is -5 or more and +5 or less. If a ^* and b ^* are within the above range, the optical film is used in the case of the mobile terminal, a yellow tone of the image becomes inconspicuous. a ^* and b ^* are measured by the same method as the method described in the first embodiment.

The haze value (total haze value) of the optical film 90 is preferably 2.5% or less for the same reason as described in the first embodiment. The haze value is measured by the same method as the method described in the first embodiment. The haze value is more preferably 1.5% or less, still more preferably 1.0% or less.

The optical reflectance (reflection Y value) of the light having a wavelength of 380 nm to 780 nm of the optical film 90 is preferably 15% or less. When the above-described visual reflectance of the optical film is 8% or less, when the optical film is used for a mobile terminal, the amount of reflected light is small and it is easy to visually recognize. The above-mentioned visual reflectance is a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation, light source: tungsten lamp and xenon lamp), and light having a wavelength of 380 nm to 780 nm is irradiated from the front side of the optical film. The light having a wavelength of 380 nm to 780 nm reflected by the optical film was measured. Specifically, the front side of the optical film cut into a size of 5 cm × 10 cm is irradiated with light having an incident angle of 5 degrees, and the reflected light reflected by the optical film in the direction of normal reflection is measured, and the reflectance in the wavelength range of 380 nm to 780 nm is measured. Thereafter, the visual reflectance is calculated by a soft body (for example, a soft body built in UV-2450) that is converted by the brightness perceived by the human eye. The above-mentioned visual reflectance is more preferably 10% or less, still more preferably 3% or less.

The other physical properties, uses, and sizes of the optical film 90 are also the same as those of the optical film 10, and thus the description thereof will be omitted.

<<Light transmissive substrate>>

The light-transmitting substrate 91 is a substrate made of a resin having light transmissivity. The thickness of the light-transmitting substrate 91 is preferably 10 μm or more and 100 μm or less for the same reason as described in the first embodiment. The thickness of the light-transmitting substrate 91 is measured by the same method as the thickness of the resin substrate 11. The lower limit of the light-transmitting substrate 91 is more preferably 25 μm or more, and the upper limit of the light-transmitting substrate 91 is more preferably 80 μm or less.

The light-transmitting substrate 91 is preferably a resin substrate. As the resin constituting the resin substrate, the same resin as the resin substrate 11 can be used, and thus the description thereof is omitted here.

<<1st antistatic layer>>

The antistatic layer 92 is a layer that imparts antistatic properties to the front surface 90A of the optical film 90. The antistatic layer 92 may have functions other than antistatic properties in addition to antistatic properties. The antistatic layer 92 has hard coat properties in addition to antistatic properties. That is, the antistatic layer 92 becomes an antistatic hard coat layer. The antistatic hard coat layer is a hard coat layer having an antistatic property.

The antistatic layer 92 preferably has a Martens hardness of 500 MPa or more and 2000 MPa or less in the center of the cross section of the antistatic layer 92. When the Martens hardness of the antistatic layer 92 is 500 MPa or more, a sufficient hardness as an antistatic hard coat layer can be obtained, and if it is 2000 MPa or less, a good optical film folding performance can be obtained. The lower limit of the Martens hardness of the center of the cross section of the antistatic layer 92 is preferably 600 MPa or more, and the upper limit is preferably 1500 MPa or less. The Martens hardness of the antistatic layer 92 is measured by the same method as the method described in the first embodiment.

The film thickness of the antistatic layer 92 is preferably 1 μm or more and 50 μm or less. When the film thickness of the antistatic layer 92 is 1 μm or more, sufficient hardness can be obtained as an antistatic hard coat layer, and if it is 50 μm or less, deterioration of workability can be suppressed. In the present specification, the "thickness of the antistatic layer" means a film thickness (total thickness) obtained by summing the film thicknesses of the respective antistatic layers when the antistatic layer has a multilayer structure. The film thickness of the antistatic layer 92 is measured by the same method as the film thickness of the functional layer 12. The upper limit of the antistatic layer 92 is more preferably 40 μm or less, and still more preferably 30 μm or less.

The antistatic layer 92 contains a binder resin and an antistatic agent present in the binder resin. In addition to the binder resin or the like, the antistatic layer 92 may contain, for example, particles such as inorganic particles or organic particles, ultraviolet absorbers, adhesion improvers, leveling agents, and thixotropy in the range which does not impair the effects of the present invention. Additives such as agents, coupling agents, plasticizers, defoamers, fillers, colorants, fillers, and the like.

<Binder resin>

The binder resin is the same as the binder resin described in the column of the functional layer 12, and thus the description thereof is omitted here.

<antistatic agent>

The antistatic agent is the same as the antistatic agent described in the column of the functional layer 12, and thus the description thereof is omitted here.

The antistatic layer 92 may further contain an ultraviolet absorber, a spectroscopic transmittance adjuster, and/or an antifouling agent. Since the ultraviolet absorber, the spectral transmittance adjusting agent, and the antifouling agent are the same as the ultraviolet absorber, the spectral transmittance adjusting agent, and the antifouling agent described in the column of the functional layer 12, description thereof will be omitted.

<<2nd antistatic layer>>

The antistatic layer 93 is a layer that imparts antistatic properties to the back surface 90B of the optical film 90. The film thickness of the antistatic layer 93 is preferably 1 nm or more and 0.5 μm or less. When the film thickness of the antistatic layer 93 is 1 nm or more, sufficient antistatic performance can be obtained, and if it is 0.5 μm or less, deterioration of workability can be suppressed. The film thickness of the antistatic layer 93 is measured by the same method as the film thickness of the functional layer 12.

When the film thickness of the antistatic layer 93 is 40 nm or more and 90 nm or less, the yellow index of the optical film 70 can be lowered. Therefore, the film thickness of the antistatic layer 93 is preferably 40 nm or more from the viewpoint of color tone adjustment. Below 90nm.

The antistatic layer 93 contains an antistatic agent. The antistatic layer 93 may contain a binder resin in addition to the antistatic agent.

<antistatic agent>

The antistatic agent contained in the antistatic layer 93 is the same as the antistatic agent described in the column of the functional layer 12, and thus the description thereof is omitted here.

<Binder resin>

The binder resin is preferably selected from the group consisting of a (meth)acrylic resin, a cellulose resin, an amine ester resin, a vinyl chloride resin, a polyester resin, a polyolefin resin, a polycarbonate, a nylon, and a polystyrene. And at least one of the group consisting of ABS resins. Among these, from the viewpoint of hardness or transparency of the binder resin, a (meth)acrylic resin or an amine ester resin is preferable.

Examples of the (meth)acrylic resin include polymethyl methacrylate and the like. Further, examples of the cellulose resin include diethyl phthalocyanine cellulose, cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB). Examples of the amine ester-based resin include an amine ester resin and the like.

Examples of the vinyl chloride-based resin include polyvinyl chloride, a vinyl chloride-vinyl acetate copolymer, and the like. Moreover, as the polyester-based resin, for example, polyethylene terephthalate or the like can be mentioned. Further, examples of the polyolefin-based resin include polyethylene and polypropylene.

<<Method of manufacturing optical film>>

The optical film 90 can be produced, for example, as follows. First, the first antistatic layer composition for obtaining the antistatic layer 92 is applied onto the first surface 91A of the light-transmitting substrate 91 by a coating device such as a bar coater to form the first composition. A coating film for a composition for an antistatic layer.

<First Antistatic Layer Composition>

The composition for the first antistatic layer contains a polymerizable compound which becomes a binder resin after curing, and an antistatic agent. The composition for the first antistatic layer may further contain an ultraviolet absorber, a spectroscopic transmittance adjuster, an antifouling agent, inorganic particles, a leveling agent, a solvent, and a polymerization initiator as needed. Since the solvent and the polymerization initiator are the same as the solvent and the polymerization initiator described in the column of the composition for a functional layer, the description thereof is omitted here.

After the coating film of the composition for the first antistatic layer is formed, the coating film is dried by heating at a temperature of, for example, 30 ° C or higher and 120 ° C or lower for 10 seconds to 120 seconds by various known methods to evaporate the solvent. .

After drying the coating film, the coating film is irradiated with ionizing radiation such as ultraviolet rays to cure the coating film. Thereby, the antistatic layer 92 is formed.

After the antistatic layer 92 is formed, a second antistatic layer for forming the antistatic layer 93 is applied onto the second surface 91B of the light-transmitting substrate 91 by a coating device such as a bar coater. A coating film of the composition for the second antistatic layer is formed.

<Second antistatic layer composition>

The composition for the second antistatic layer contains an antistatic agent and a solvent. The second antistatic layer may further contain a binder resin. The solvent is the same as the solvent described in the column for the functional layer composition, and thus the description thereof is omitted here.

After the coating film of the composition for the second antistatic layer is formed, the coating film is dried by heating at a temperature of, for example, 30° C. or higher and 120° C. or lower for 10 seconds to 120 seconds by various known methods to evaporate the solvent. Thereby, the antistatic layer 93 can be formed, and the optical film 90 shown in FIG. 10 can be obtained.

<<<Other optical film>>

The optical film may also be the optical film 100 shown in FIG. The optical film 100 shown in Fig. 11 is also used for an image display device and can be folded.

The optical film 100 includes a light-transmitting substrate 101 and a hard coat layer 102 which is provided on the first surface 101A side of the light-transmitting substrate 101 as a functional layer, and a first antistatic layer 103 (hereinafter sometimes referred to as a short surface) An antistatic layer 103) disposed on a side of the hard coat layer 102 opposite to the side of the light-transmitting substrate 101; and an optical adjustment layer 104 disposed on a side of the antistatic layer 103 opposite to the side of the hard coat layer 102; The second antistatic layer 105 (hereinafter sometimes referred to simply as the antistatic layer 105) is provided on the side of the second surface 101B which is the surface opposite to the first surface 101A of the light-transmitting substrate 101. The physical properties and the like of the optical film 100 are the same as those of the optical film 100, and thus the description thereof is omitted here.

The front surface 100A of the optical film 100 serves as the front surface 104A of the optical adjustment layer 104. The back surface 100B of the optical film 100 is a surface 105A on the opposite side to the surface of the antistatic layer 105 on the side of the light-transmitting substrate 101.

<<Light transmissive substrate and hard coating>>

Since the light-transmitting substrate 101 is the same as the light-transmitting substrate 91, the description thereof is omitted here. The hard coat layer 102 is the same as the antistatic layer 92 except that it does not contain an antistatic agent, and thus the description thereof is omitted here.

<<1st antistatic layer and 2nd antistatic layer>>

Since the antistatic layers 103 and 105 are the same as those of the antistatic layer 93, the description thereof is omitted here. That is, the antistatic layer 103 does not have hard coat properties.

<<Optical adjustment layer>>

The optical adjustment layer 104 is a layer for adjusting the optical properties such as the hue or reflectance of the optical film 100. When a base material containing a polyimide resin is used as the light-transmitting substrate, the light-transmitting substrate exhibits a yellow color. Therefore, the optical adjustment layer 104 is made of a substrate containing a polyimide resin as a light-transmitting property. The substrate 91 is particularly effective.

The film thickness of the optical adjustment layer 104 is preferably 30 nm or more and 500 nm or less. When the film thickness of the optical adjustment layer 104 is 30 nm or more, optical characteristics (transmittance, reflectance, and hue) can be adjusted, and if it is 500 nm or less, deterioration of processing can be suppressed. The film thickness of the optical adjustment layer 104 is measured by the same method as the film thickness of the functional layer 12. The upper limit of the optical adjustment layer 104 is more preferably 400 nm or less, further preferably 200 nm or less.

When the film thickness of the optical adjustment layer 104 is 30 nm or more and 300 nm or less, the refractive index of the optical adjustment layer 104 is preferably lower than the refractive index of the antistatic layer 103. With such a configuration, the optical adjustment layer 104 functions as a low refractive index layer, so that the reflectance of external light can be lowered. In this case, the refractive index of the optical adjustment layer 104 is preferably 1.38 or more and 1.60 or less. The refractive index of the optical adjustment layer 104 or the antistatic layer 103 can be made by using a refractive index measured by a spectrophotometer and a Fresnel-type film by setting a refractive index of a wavelength region of 380 nm or more and 780 nm or less. The spectrum calculated by the optical model is obtained by fitting. Further, the refractive index of the optical adjustment layer 104 or the antistatic layer 103 may be determined by forming an individual layer and measuring by an Abbe refractometer (product name "NAR-4T", manufactured by Atago Corporation) or an ellipsometer. Out. Moreover, as a method of measuring the refractive index after the optical film 100, a method of cutting the optical adjustment layer 104 or the antistatic layer 103 by a cutter or the like to prepare a sample in a powder state according to JIS K7142: 2008 can be used. B-line method of B method (for powder or granular transparent material) (refractive index using a known Cargille reagent, placing the above-mentioned powder state sample on a glass slide, etc., dropping a reagent onto the sample, and taking the sample Immersed in the reagent; observing the condition by microscopic observation, the refractive index of the reagent of the bright line (Becker line) generated in the contour of the sample due to the difference in refractive index between the sample and the reagent cannot be visually observed as the refractive index of the sample. Methods). The absolute value of the refractive index difference between the antistatic layer 103 and the optical adjustment layer 104 is preferably 0.005 or more. The upper limit of the absolute value of the refractive index difference between the antistatic layer 103 and the optical adjustment layer 104 is preferably 0.3 or less.

The optical adjustment layer 104 is made of, for example, an inorganic oxide such as ruthenium oxide or aluminum oxide. The optical adjustment layer 104 can be formed, for example, by a vapor deposition method such as a physical vapor deposition (PVD) method or a chemical vapor deposition (CVD) method such as a sputtering method or an ion plating method.

The optical adjustment layer 104 may also contain an antifouling agent. The antifouling agent is the same as the antifouling agent described in the column of the functional layer 12, and thus the description thereof is omitted here.

<<<Image Display Device>>

The optical films 90, 100 can be incorporated into a collapsible image display device for use. Fig. 12 is a view showing the schematic configuration of a video display device of the embodiment. As shown in FIG. 12, the video display device 110 faces the viewer side, and mainly houses a casing 81 for accommodating a battery or the like, a protective film 82, a display element 83, a circular polarizing plate 84, a touch sensor 85, and optical. Film 90. An adhesive layer 86 having a light transmissive property is disposed between the display element 83 and the circular polarizing plate 84, between the circular polarizing plate 84 and the touch sensor 85, and between the touch sensor 85 and the optical film 90. The members are fixed to each other by the adhesive layer 86. In FIG. 12, members having the same reference numerals as those in FIG. 9 are the same as those shown in FIG. 9, and thus the description thereof is omitted.

The optical film 90 is disposed such that the antistatic layer 92 is closer to the viewer than the light-transmitting substrate 91. In the image display device 110, the front surface 90A of the optical film 90 (the front surface 92A of the antistatic layer 92) constitutes the front surface 110A of the image display device 110.

According to the present embodiment, the optical film 90 is provided with the antistatic layers 92 and 93 on both sides of the light-transmitting substrate 91, and the optical film 100 is provided with the antistatic layers 103 and 105 on both sides of the light-transmitting substrate 101. Dust or the like adheres to the optical films 90 and 100. Further, in a state in which a protective film (not shown) is attached to both surfaces of the optical films 90 and 100, even if the protective film is peeled off from the optical films 90 and 100, charging of the optical films 90 and 100 can be suppressed. Thereby, the yield of the assembly steps of the image display device can be improved.

Since the optical adjustment layer is a film, the optical film can be improved in scratch resistance without providing an optical adjustment layer. Since the optical film 90 does not have an optical adjustment layer on the antistatic layer 92, the scratch resistance is superior to that of the optical film 100 including the optical adjustment layer 104 on the antistatic layer 103.

In a collapsible optical film, the binder resin of the hard coat layer must be selected in a foldable manner. Further, if the antistatic agent is kneaded in the hard coat layer like the optical film 90, it is necessary to use an antistatic agent which exhibits good compatibility with the selected binder resin, resulting in less options for the antistatic agent. On the other hand, in the optical film 100, since the antistatic layer 103 is made of a layer different from the hard coat layer 102, the option of the antistatic agent can be expanded.

[Examples]

In order to explain the present invention in detail, the following examples are described, but the present invention is not limited to the description. In addition, the following "100% conversion value of a solid content" is a value when the solid content in the solvent dilution product is 100%.

<Preparation of Composition for Optical Adjustment Layer>

First, each component was blended so as to have a composition shown below, and a composition for an optical adjustment layer was obtained.

(Composition for optical adjustment layer 1)

‧ Amine ester modified polyester resin (product name "UR-3200", manufactured by Toyobo Co., Ltd.): 85 parts by mass (100% conversion value of solid content)

‧ Zirconia (average particle size: 20 nm, manufactured by CIK NanoTek): 15 parts by mass (100% conversion of solid content)

‧Methyl isobutyl ketone (MIBK): 170 parts by mass

(Composition for optical adjustment layer 2)

‧Amino ester modified polyester resin (product name "UR-1700", manufactured by Toyobo Co., Ltd.): 70 parts by mass (100% conversion value of solid content)

‧ Zirconia (average particle size 20 nm, manufactured by CIK NanoTek Co., Ltd.): 30 parts by mass (100% converted solid content)

‧Methyl isobutyl ketone (MIBK): 170 parts by mass

(Composition for optical adjustment layer 3)

‧Antistatic agent containing quaternary ammonium salt (product name "1SX-3000", manufactured by Taisei Fine Chemical Co., Ltd.): 100 parts by mass (100% conversion of solid content)

‧Photopolymerization initiator (product name "Irg184", manufactured by BASF Japan): 4 parts by mass

‧Methyl isobutyl ketone (MIBK): 150 parts by mass

(Construction 4 for optical adjustment layer)

‧Amino ester modified polyester resin (product name "UR-3200", manufactured by Toyobo Co., Ltd.): 70 parts by mass (100% conversion value of solid content)

‧ Zirconia (average particle size 20 nm, manufactured by CIK NanoTek): 15 parts by mass (100% conversion of solid component)

‧Cobalt blue (average particle size 40nm, manufactured by CIK NanoTek): 15 parts by mass (100% conversion of solid content)

‧Methyl isobutyl ketone (MIBK): 170 parts by mass

(Construction for optical adjustment layer 5)

‧Polyolefin resin (product name "P-901", manufactured by Mitsui Chemicals Co., Ltd.): 70 parts by mass (100% conversion value of solid content)

‧ Zirconia (average particle size 20 nm, manufactured by CIK NanoTek Co., Ltd.): 30 parts by mass (100% converted solid content)

‧Methyl isobutyl ketone (MIBK): 170 parts by mass

<Preparation of composition for antistatic layer>

First, each component is blended so as to have a composition shown below, and a composition for an antistatic layer is obtained.

(Antistatic layer composition 1)

‧ a mixture of pentaerythritol triacrylate and neopentyl alcohol tetraacrylate (product name "KAYARAD PET-30", manufactured by Nippon Kayaku Co., Ltd.): 90 parts by mass

‧Antistatic polymer containing quaternary ammonium salt (product name "UV-ASHC-01", manufactured by Nippon Kasei Co., Ltd.): 10 parts by mass

‧ Polymerization initiator (product name "Irgacure (registered trademark) 184", manufactured by BASF): 2 parts by mass

(Antistatic layer composition 2)

‧Antistatic polymer containing quaternary ammonium salt (product name "UV-ASHC-01", manufactured by Nippon Kasei Co., Ltd.): 100 parts by mass

‧ Polymerization initiator (product name "Irgacure (registered trademark) 184", manufactured by BASF): 0.5 parts by mass

<Composition for hard coat layer>

Each component was blended so as to have a composition shown below to obtain a composition for a hard coat layer.

(Composition for hard coating 1)

‧ Amine ester resin (product name "U-6LPA", manufactured by Shin-Nakamura Chemical Co., Ltd.): 70 parts by mass

‧ Amine ester resin (product name "UV2750B", manufactured by Nippon Synthetic Chemical Co., Ltd.): 20 parts by mass

‧Antistatic agent containing quaternary ammonium salt (product name "1SX-3000", manufactured by Taisei Fine Chemical Co., Ltd.): 10 parts by mass (100% conversion value of solid content)

‧Photopolymerization initiator (product name "Irg184", manufactured by BASF): 4 parts by mass

‧ UV absorber (product name "TINUVIN477", manufactured by BASF): 5 parts by mass (100% conversion of solid content)

‧Antifouling agent (product name "BYKUV3500", manufactured by BYK-Chemie): 1.5 parts by mass (100% conversion of solid content)

‧Methyl isobutyl ketone (MIBK): 150 parts by mass

(Composition for hard coating 2)

‧ a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (product name "KAYARAD PET-30", manufactured by Nippon Kayaku Co., Ltd.): 100 parts by mass

‧ Polymerization initiator (product name "Irgacure (registered trademark) 184", manufactured by BASF): 2 parts by mass

<Preparation of Composition for Resin Layer>

Each component was blended so as to have a composition shown below to obtain a composition for a resin layer.

(Composition for resin layer 1)

‧Acetyl acrylate (product name "UV3310B", manufactured by Nippon Synthetic Chemical Co., Ltd., Ernest): 85 parts by mass

‧Phenyloxyethyl acrylate (product name "Viscoat #192", manufactured by Osaka Organic Chemical Industry Co., Ltd.): 5 parts by mass

‧Three neopentyl alcohol acrylate, mono- and dipentaerythritol acrylate, and a mixture of polypentaerythritol acrylate (product name "Viscoat #802", manufactured by Osaka Organic Chemical Industry Co., Ltd.): 10 parts by mass

‧ Polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan): 5 parts by mass

‧Methyl isobutyl ketone: 10 parts by mass

(Composition for resin layer 2)

‧Acetylamine (product name "UV3310B", manufactured by Nippon Synthetic Chemical Co., Ltd., difunctional): 85 parts by mass

‧Phenyloxyethyl acrylate (product name "Viscoat #192", manufactured by Osaka Organic Chemical Industry Co., Ltd.): 15 parts by mass

‧ Polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan): 5 parts by mass

‧Methyl isobutyl ketone: 10 parts by mass

(Composition for resin layer 3)

‧Acetylamine (product name "UV3310B", manufactured by Nippon Synthetic Chemical Co., Ltd., difunctional): 80 parts by mass

‧Phenyloxyethyl acrylate (product name "Viscoat #192", manufactured by Osaka Organic Chemical Industry Co., Ltd.): 5 parts by mass

‧Three neopentyl alcohol acrylate, mono- and dipentaerythritol acrylate, and a mixture of polypentaerythritol acrylate (product name "Viscoat #802", manufactured by Osaka Organic Chemical Industry Co., Ltd.): 10 mass parts

‧ Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (product name "KAYARAD DPHA", manufactured by Nippon Kayaku Co., Ltd.): 5 parts by mass

‧ Polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan): 5 parts by mass

‧Methyl isobutyl ketone: 10 parts by mass

(Composition for resin layer 4)

‧Acetylamine (product name "UV3310B", manufactured by Nippon Synthetic Chemical Co., Ltd., difunctional): 95 parts by mass

‧Phenyloxyethyl acrylate (product name "Viscoat #192", manufactured by Osaka Organic Chemical Industry Co., Ltd.): 5 parts by mass

‧ Polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan): 5 parts by mass

‧Methyl isobutyl ketone: 10 parts by mass

(Composition for resin layer 5)

‧Acetylamine (product name "UV3310B", manufactured by Nippon Synthetic Chemical Co., Ltd., difunctional): 85 parts by mass

‧ Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (product name "KAYARAD DPHA", manufactured by Nippon Kayaku Co., Ltd.): 15 parts by mass

‧ Polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan): 5 parts by mass

‧Methyl isobutyl ketone: 10 parts by mass

<<Example A and Comparative Example A>>

<Example A1>

A polyimide-based substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) having a refractive index of 1.630 and a thickness of 30 μm was prepared as a resin substrate, and was used as a surface of a polyimide-based substrate by a bar coater. The composition 2 for the optical adjustment layer was applied to the first surface to form a coating film. Thereafter, the formed coating film was heated at 90 ° C for 1 minute to evaporate the solvent in the coating film to form a second optical adjustment layer having a refractive index of 1.562 and a film thickness of 100 nm. After the formation of the second optical adjustment layer, the composition for optical adjustment layer 1 is applied onto the surface of the second optical adjustment layer by a bar coater to form a coating film. Thereafter, the formed coating film was heated at 90 ° C for 1 minute to evaporate the solvent in the coating film to form a first optical adjustment layer having a refractive index of 1.544 and a film thickness of 100 nm. After the formation of the first optical adjustment layer, the composition 1 for the hard coat layer was applied onto the surface of the first optical adjustment layer by a bar coater to form a coating film. Thereafter, the formed coating film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film, and an ultraviolet irradiation device (manufactured by Fusion UV System Japan Co., Ltd., light source H BULB) was used in the air. The coating film was cured by irradiating ultraviolet rays so as to have an integrated light amount of 200 mJ/cm ^{2 to} form a hard coat layer having a refractive index of 1.531 and a film thickness of 10 μm. Thereby, the first optical adjustment layer is adjacent to the hard coat layer, and the second optical adjustment layer is adjacent to the optical film of the polyimide film. Further, the front surface of the optical film of Example A1 was the surface of the hard coat layer, and the back surface was the second surface of the polyimide-based substrate opposite to the first surface.

The refractive index of the hard coat layer and the optical adjustment layer is applied to the composition for a hard coat layer and the composition for an optical adjustment layer on a PET having a thickness of 50 μm which is not easily treated, and a cured film having a thickness of 1 to 10 μm is formed. A black polyvinyl chloride insulating tape (for example, Yamato vinyl tape NO200-38) having a width larger than a measuring point area is attached to the surface of the uncoated hard coating composition or the optical conditioning layer composition (back surface) of PET. -21 38mm width) The average reflectance at a wavelength of 380 to 780 nm is measured using a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation) using a spectrophotometer (product name "UV-2450"), and the average reflectance obtained is based on the above formula ( 2) and find. In Examples A2 to A12 and Comparative Examples A1 and A2, the refractive indices of the respective layers were also measured by the same method as in Example A1.

Further, the film thickness of each layer was measured by a scanning transmission electron microscope (STEM) (product name "S-4800", manufactured by Hitachi High-Technologies Co., Ltd.), and 20 sections were measured in the image of the section. The film thickness of each layer was calculated using the arithmetic mean of the film thickness of the 20 parts. The cross-sectional photograph of the optical film was taken as follows. First, a block in which an optical film cut at 1 mm × 10 mm is embedded in an embedding resin is produced, and a uniform thickness of no pores or the like is cut out from the block by a general slicing method to a thickness of 70 nm or more and 100 nm or less. Sliced. For the production of the slice, "Ultramicrotome EM UC7" (Leica Microsystems Co., Ltd.) or the like was used. Then, a uniform slice having no pores or the like was used as a measurement sample. Thereafter, a cross-sectional photograph of the sample was measured using a scanning transmission electron microscope (STEM). In the photographing of the cross-sectional photograph, the detector was set to "TE", the acceleration voltage was set to "30 kV", and the emission current was set to "10 μA" to perform STEM observation. Regarding the magnification, the focal length is adjusted and the layers are distinguished or observed by contrast and brightness, and the magnification is appropriately adjusted from 5000 times to 200,000 times. In addition, when the cross-sectional photograph is taken, the aperture is set to "beam detection aperture 3", the objective aperture is set to "3", and W.D. is set to "8 mm". In Examples A2 to A12 and Comparative Examples A1 and A2, the refractive index and film thickness of each layer were also measured by the same method as in Example A1.

<Example A2>

In the example A2, a third optical adjustment layer having a refractive index of 1.536 and a film thickness of 100 nm was formed on the surface of the polyimide-based substrate on the side opposite to the surface on the second optical adjustment layer side, and An optical film was obtained in the same manner as in Example 1. The third optical adjustment layer is formed by coating the optical adjustment layer composition 3 on the second surface of the polyimide substrate by a bar coater to form a coating film. The film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film, and the cumulative amount of light in the air was 100 mJ/cm ² using an ultraviolet irradiation device (manufactured by Fusion UV System Japan, light source H BULB). The method is to irradiate ultraviolet rays to harden the coating film. Further, the front surface of the optical film of Example A2 was the surface of the hard coat layer, and the back surface was the surface of the third optical adjustment layer.

<Example A3>

In the same manner as in Example A1, an optical film was obtained in the same manner as in Example A1 except that the film thickness of the first optical adjustment layer was changed to 200 nm.

<Example A4>

In the same manner as in Example A1, an optical film was obtained in the same manner as in Example A1 except that the film thickness of the second optical adjustment layer was changed to 200 nm.

<Example A5>

An optical film was obtained in the same manner as in Example A1 except that the composition for optical adjustment layer 4 was used instead of the composition for optical adjustment layer 4 in Example A5. Further, the refractive index of the first optical adjustment layer formed using the composition for optical adjustment layer 4 was 1.547.

<Example A6>

An optical film was obtained in the same manner as in Example A1 except that the composition for optical adjustment layer 5 was used instead of the composition for optical adjustment layer 5 in Example A6. Further, the refractive index of the second optical adjustment layer formed using the composition for optical adjustment layer 5 was 1.563.

<Example A7>

In the same manner as in Example A1, an optical film was obtained in the same manner as in Example A1 except that the film thickness of the hard coat layer was changed to 20 μm.

<Example A8>

In the same manner as in Example A1, an optical film was obtained in the same manner as in Example A1 except that the film thickness of the hard coat layer was 40 μm.

<Example A9>

In Example A9, a polyamidimide-based substrate (product name "THD-30", manufactured by Kolon Co., Ltd.) having a refractive index of 1.662 and a thickness of 30 μm was used instead of the polyimide-based substrate, and An optical film was obtained in the same manner as in Example A1.

<Example A10>

In the example A10, a polyamidamide-based substrate (product name "aromatic polyamine", manufactured by Toray Co., Ltd.) having a refractive index of 1.701 and a thickness of 30 μm was used instead of the polyimide-based substrate, and An optical film was obtained in the same manner as in Example A1.

<Example A11>

In the same manner as in Example A1, except that a polyester-based substrate (product name "U403", manufactured by Toray Co., Ltd.) having a refractive index of 1.654 and a thickness of 23 μm was used instead of the polyimide-based substrate in Example A11. The optical film is obtained in a manner.

<Example A12>

A polyimide-based substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) having a refractive index of 1.630 and a thickness of 30 μm was prepared as a resin substrate, and was used as a polyimide-based substrate by a bar coater. A coating film is formed by coating the composition 1 for an optical adjustment layer on the first surface of one surface. Thereafter, the formed coating film was heated at 90 ° C for 1 minute to evaporate the solvent in the coating film to form a refractive index of 1.544 and a film thickness of 100 nm adjacent to the polyimide substrate. 1 optical adjustment layer. After the formation of the first optical adjustment layer, the composition 1 for the hard coat layer was applied onto the surface of the first optical adjustment layer by a bar coater to form a coating film. Then, the formed coating film was heated at 90 ° C for 1 minute to evaporate the solvent in the coating film, and an ultraviolet irradiation device (manufactured by Fusion UV System Japan Co., Ltd., light source H BULB) was used in the air. The coating film was cured by irradiating ultraviolet rays so as to have an integrated light amount of 200 mJ/cm ^{2 to} form a hard coat layer having a refractive index of 1.531 and a film thickness of 10 μm. Thereby, the optical film in which the first optical adjustment layer is adjacent to the hard coat layer and the polyimide substrate is obtained. Further, the front surface of the optical film of Example A1 was the surface of the hard coat layer, and the back surface was the second surface of the polyimide-based substrate opposite to the first surface.

<Example A13>

In the example A13, a polyamidimide-based substrate (product name "THD-30", manufactured by Kolon Co., Ltd.) having a refractive index of 1.662 and a thickness of 30 μm was used instead of the polyimide-based substrate, and An optical film was obtained in the same manner as in Example A12.

<Example A14>

In Example 14, a polyimide substrate (product name "aromatic polyamide", manufactured by Toray Co., Ltd.) having a refractive index of 1.701 and a thickness of 30 μm was used instead of the polyimide substrate, and An optical film was obtained in the same manner as in Example A12.

<Example A15>

In the same manner as in Example A12, a polyester-based substrate (product name "U403", manufactured by Toray Co., Ltd.) having a refractive index of 1.654 and a thickness of 23 μm was used instead of the polyimide-based substrate in Example A15. The optical film is obtained in a manner.

<Example A16>

In the same manner as in Example A12, the resin layer was formed in the same manner as in Example A12 except that the resin layer was formed on the surface opposite to the surface on the side of the first optically-adjusting layer of the polyimide-based substrate. membrane. When the resin layer is formed, the resin layer composition 1 is applied to the surface of the polyimide-based substrate on the side opposite to the surface on the first optical adjustment layer side by a bar coater to form a coating film. Then, the formed coating film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film, and was accumulated in the air using an ultraviolet irradiation device (manufactured by Fusion UV System Japan, light source H BULB). When the amount of light was 1200 mJ/cm ^{2 ,} the coating film was cured by irradiation with ultraviolet rays, and a resin layer composed of an amine ester resin having a refractive index of 1.504 and a film thickness of 200 μm was formed.

<Example A17>

In the same manner as in Example A16, an optical film was obtained in the same manner as in Example A16 except that the film thickness of the resin layer was changed to 50 μm.

<Example 18>

In the same manner as in Example A16, an optical film was obtained in the same manner as in Example A16 except that the film thickness of the resin layer was changed to 300 μm.

<Example A19>

An optical film was obtained in the same manner as in Example A16 except that the resin layer composition 2 was used instead of the resin layer composition 1 in Example A19. Further, the refractive index of the resin layer formed using the composition 2 for a resin layer was 1.509.

<Example A20>

An optical film was obtained in the same manner as in Example A16 except that the resin layer composition 3 was used instead of the resin layer composition 1 in Example A20. Further, the refractive index of the resin layer formed using the composition 3 for a resin layer was 1.507.

<Example A21>

An optical film was obtained in the same manner as in Example A20 except that the film thickness of the resin layer was changed to 50 μm.

<Example A22>

In the same manner as in Example A20, an optical film was obtained in the same manner as in Example A20 except that the film thickness of the resin layer was changed to 300 μm.

<Example A23>

In the same manner as in Example A16, an optical film was obtained in the same manner as in Example A16 except that a third optical adjustment layer having a refractive index of 1.536 and a thickness of 100 nm was formed between the polyimide and the resin layer. The third optical adjustment layer is formed by coating the optical adjustment layer composition 3 on the second surface of the polyimide substrate by a bar coater to form a coating layer before forming the resin layer. The film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film, and was accumulated in the air using an ultraviolet irradiation device (manufactured by Fusion UV System Japan, light source H BULB). light quantity becomes 100mJ / cm ² of the cured coating film irradiated with ultraviolet rays. The resin layer was formed on the surface of the third optical adjustment layer in the same manner as in Example A16 after the formation of the third optical adjustment layer. Further, the front surface of the optical film of Example A23 was the surface of the hard coat layer, and the back surface was the surface of the resin layer.

<Example A24>

In the example A24, a resin layer composed of an amine ester resin having a refractive index of 1.504 and a film thickness of 200 μm was formed on the surface opposite to the surface of the third optically-adjusting layer on the side of the polyimide-based substrate. Except for this, an optical film was obtained in the same manner as in Example A2. The resin layer was formed on the surface of the third optical adjustment layer in the same manner as in Example A16.

<Comparative Example A1>

A polyimide-based substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) having a refractive index of 1.630 and a thickness of 30 μm was prepared as a resin substrate, and was used as a surface of a polyimide-based substrate by a bar coater. The first surface of the hard coat layer was coated with the composition 1 to form a coating film. Thereafter, the formed coating film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film, and an ultraviolet irradiation device (manufactured by Fusion UV System Japan Co., Ltd., light source H BULB) was used in the air. The coating film was cured by irradiating ultraviolet rays so as to have an integrated light amount of 200 mJ/cm ² , and a hard coat layer having a film thickness of 10 μm was formed to obtain an optical film having a hard coat layer adjacent to the polyimide film. Further, the front surface of the optical film of Comparative Example A1 was the surface of the hard coat layer, and the back surface was the surface of the polyimide-based base material opposite to the first surface.

<Comparative Example A2>

In the same manner as in Comparative Example A1, an optical film was obtained in the same manner as in Comparative Example A1 except that the film thickness of the hard coat layer was changed to 50 μm.

<Comparative Example A3>

In Comparative Example A3, an optical film was obtained in the same manner as in Comparative Example A1 except that a resin layer was formed on the surface of the polyimide-based substrate on the side opposite to the surface on the hard coat layer side. When the resin layer is formed, first, the resin layer composition 1 is applied to the surface of the polyimide-based substrate on the side opposite to the surface of the hard coat layer by a bar coater to form a coating film. Then, the formed coating film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film, and was accumulated in the air using an ultraviolet irradiation device (manufactured by Fusion UV System Japan, light source H BULB). When the amount of light was 1200 mJ/cm ^{2 ,} the coating film was cured by irradiation with ultraviolet rays, and a resin layer composed of an amine ester resin having a refractive index of 1.504 and a film thickness of 30 μm was formed.

<Comparative Example A4>

In the same manner as in Comparative Example A3, an optical film was obtained in the same manner as in Comparative Example A3 except that the film thickness of the resin layer was changed to 350 μm.

<Comparative Example A5>

In Comparative Example A5, an optical film was obtained in the same manner as in Comparative Example A3 except that the resin layer composition 4 was used instead of the resin layer composition 1 to form a resin layer having a thickness of 200 μm. Further, the refractive index of the resin layer formed using the composition 4 for a resin layer was 1.506.

<Comparative Example A6>

In Comparative Example A6, an optical film was obtained in the same manner as in Comparative Example A3 except that the resin layer composition 5 was used instead of the resin layer composition 1 to form a resin layer having a thickness of 200 μm. Further, the refractive index of the resin layer formed using the composition 5 for a resin layer was 1.509.

<Comparative Example A7>

An optical film was obtained in the same manner as in Example A1 except that the film thickness of the first optical adjustment layer was changed to 3 μm (3000 nm) in Comparative Example A7.

<Interference fringe evaluation>

In the optical films of Examples A1 to A24 and Comparative Examples A1 to A7, whether or not interference fringes were observed was evaluated. Specifically, a black acryl plate for preventing back reflection was attached to the back surface of the optical film via a transparent adhesive, and each optical film was irradiated with light from the front side of the optical film, and it was visually observed whether interference fringes were confirmed. As the light source, a three-wavelength tube fluorescent lamp is used. The generation of interference fringes was evaluated according to the following criteria.

◎: No interference fringes were confirmed.

○: Although a little interference fringe was confirmed, there was no problem in actual use.

×: The interference fringes were clearly confirmed.

<Continuous folding and adhesion before durability test>

The optical films of Examples A1 to A24 and Comparative Examples A1 to A7 were cut into a rectangular shape of 30 mm × 100 mm to prepare a sample, and the sample was attached to an endurance tester (product name "DLDMLH-FS", manufactured by Yuasa System Co., Ltd.) as follows. In other words, the short side (30 mm) side of the sample is fixed by the fixing portion, and as shown in Fig. 2(C), the minimum interval between the two opposite sides is 10 mm, and the front side of the sample is 10,000 times. A side-folding 180° continuous folding test (a test in which the hard coat layer becomes the inner side and the substrate, the third optical adjustment layer or the resin layer is folded outward), whether or not the substrate and the hard coat layer are not produced Bulge (gap), and whether the bend does not break or break. The results of the continuous folding test were classified into continuous folding property and adhesion, and were evaluated according to the following criteria. Further, the sample used in the continuous folding test was an optical film cutter before the durability test described below.

(continuous folding)

◎: In the continuous folding test, no crack or breakage occurred in the bent portion.

○: In the continuous folding test, a slight crack or break occurred in the bent portion, but there was no problem in practical use.

×: In the continuous folding test, cracks or breaks were apparently formed in the bent portion.

(adhesiveness)

◎: In the continuous folding test, no bulging occurred between the substrate and the hard coat layer.

○: In the continuous folding test, a slight bulging occurred between the substrate and the hard coat layer, but there was no problem in practical use.

X: In the continuous folding test, bulging was apparently generated between the substrate and the hard coat layer.

<Continuous folding and adhesion after durability test>

For the optical films of Examples A1 to A24 and Comparative Examples A1 to A7, the durability test of placing the optical film in an environment of 60 ° C and a relative humidity of 90% for 12 hours was carried out, and the optical film after the durability test was cut into 30 mm. A sample was prepared in a rectangular shape of ×100 mm, and the sample was attached to an endurance tester (product name "DLDMLH-FS", manufactured by Yuasa System Co., Ltd.) in such a manner that the short side (30 mm) side of the sample was fixed by the fixing portion, respectively. As shown in Fig. 2(C), the minimum interval between the two opposite sides is 10 mm, and the continuous folding test of folding the front side of the sample by 180° is performed 10,000 times (the hard coat layer is formed inside and the substrate is formed). The test in which the third optical adjustment layer or the resin layer was folded outward was examined. Whether or not ridges (gap) were not generated between the substrate and the hard coat layer, and whether cracks or breaks were not formed in the bent portion were examined. The results of the continuous folding test were classified into continuous folding property and adhesion, and were evaluated according to the following criteria.

(continuous folding)

◎: In the continuous folding test, no crack or breakage occurred in the bent portion.

○: In the continuous folding test, a slight crack or break occurred in the bent portion, but there was no problem in practical use.

×: In the continuous folding test, cracks or breaks were apparent in the bent portion.

(adhesiveness)

◎: In the continuous folding test, no bulging occurred between the substrate and the hard coat layer.

○: In the continuous folding test, a slight bulging occurred between the substrate and the hard coat layer, but there was no problem in practical use.

X: In the continuous folding test, bulging was apparently generated between the substrate and the hard coat layer.

<pencil hardness>

The pencil hardness of the front surface of the optical films of Examples A1 to A24 and Comparative Examples A1 to A7 was measured based on JIS K5600-5-4:1999. The pencil hardness test was carried out by fixing an optical film cut out at a size of 30 mm × 100 mm to a glass plate by using Cellotape (registered trademark) manufactured by Nichiban Co., Ltd. without bending or wrinkling. For the front side of the optical film, use a pencil hardness tester (product name "Pencil Scratch Film Hardness Tester (Electric)", manufactured by Toyo Seiki Co., Ltd.), and face a pencil (product name "Uni", Mitsubishi Pencil Co., Ltd.) applied a load of 750 g to move the pencil at a moving speed of 1 mm/sec. The pencil hardness was set to the highest hardness that did not cause damage to the front side of the optical film in the pencil hardness test. Furthermore, in the measurement of pencil hardness, a pencil having a different hardness is used, and a pencil hardness test is performed 5 times for each pencil, and the front surface of the optical film is penetrated under a fluorescent lamp 4 times or more in 5 times. When the damage was not observed on the front side of the optical film at the time of observation, it was judged that the pencil of the hardness did not cause damage to the front surface of the optical film. Further, as the optical film, the optical film before the above durability test was used.

<Anti-stripping chargeability>

The protective film was bonded to the front surface of the optical films of Examples A1 to A24 and Comparative Examples A1 to A7, and the amount of peeling charge when the protective film was peeled off from the front surface of the optical film was measured, and the amount of peeling charge was evaluated. Specifically, a protective film (product name "SAT2038T-JSL", manufactured by SUN A. KAKEN Co., Ltd.) with an adhesive layer attached to the front surface of the optical film is applied to the optical film at 23 ° C and a relative humidity of 50%. The protective film was peeled at 180° on the front side at a peeling speed of 300 mm/min, and the potential of the front side of the optical film at this time was measured using an electrostatic measuring device (product name "KSD-0103", manufactured by Kasuga Electric Co., Ltd.) at a distance of 50 mm from the front surface. , the stripping charge was measured. The peeling charge amount was measured 10 times on the front side of the optical film, and the arithmetic mean value of the peeling charge amount obtained by measuring 10 times was used. The evaluation criteria are as follows. Further, as the optical film, the optical film before the above durability test was used.

○: The peeling charge amount of the front side of the optical film was in the range of -10 kV to 10 kV.

×: The peeling power amount of the front side of the optical film exceeded ±10 kV.

<saturation band voltage>

The saturation band voltages on the front side of the optical films of Examples A1 to A24 and Comparative Examples A1 to A7 were measured. Specifically, in an environment of 23° C. and a relative humidity of 50%, a voltage of 10 kV is applied from a front surface of the optical film cut at a distance of 100 mm×100 mm to a distance of 50 mm, and a charged charge decay degree measuring device (product name) is used. "H-0110", manufactured by Shishido Electrostatic Co., Ltd.), measured the saturation band voltage of the front side of the optical film. The saturation band voltage was set to the arithmetic mean of the values obtained by measuring 3 times. Further, as the optical film, the optical film before the above durability test was used.

<surface resistance value>

In the optical films of Examples A1 to A24 and Comparative Examples A1 to A7, the resistance value of the surface was measured using a resistivity meter (product name "Hiresta-UP MCP-HT450", manufactured by Mitsubishi Chemical Analytech Co., Ltd., probe: URS). The surface resistance value was measured by randomly measuring the surface resistance value of the front surface of the optical film cut out at a size of 50 mm × 50 mm at 10 locations, and the arithmetic mean value of the surface resistance values of the measured 10 portions was used. Further, as the optical film, the optical film before the above durability test was used.

<Yellow Index (YI)>

In the optical films of Examples A1 to A24 and Comparative Examples A1 to A7, the yellow index was measured. Specifically, the optical film cut out at a size of 50 mm × 50 mm is placed on a spectrophotometer (product name "UV-2450", which is manufactured by Shimadzu Corporation, so that the substrate side of the optical film becomes the light source side. , light source: tungsten light and xenon lamp). The optical film system is free from defects (mixing of foreign matter), no cracks, no wrinkles, and no stains, and is held in a spectrophotometer in a state of no curl. In this state, the transmittance of the lowest five points was measured between the wavelengths of 300 nm and 780 nm at a wavelength of 300 nm to 780 nm, and the average value of the five points was calculated under the following conditions. Then, the measurement data of the above-described transmittance is read on a monitor connected to the UV-2450, and YI is obtained by checking "YI" in the calculation item. Further, as the optical film, the optical film before the above durability test was used.

(measurement conditions)

‧wavelength region: 300nm~780nm

‧Scanning speed: high speed

‧ slit width: 2.0

‧Sampling interval: automatic (0.5nm interval)

‧Lighting: C

‧Light source: D2 and WI

‧Field of view: 2°

‧Light source switching wavelength: 360nm

‧S/R switching: standard

‧Detector: PM

‧Automatic zero: implemented at 550nm after scanning of the baseline

<Measurement of total light transmittance>

For the optical films of Examples A1 to A24 and Comparative Examples A1 to A7, a haze meter (product name "HM-150", manufactured by Murakami Color Technology Co., Ltd.) was used, and total light was measured in accordance with JIS K7361-1:1997. Penetration rate. With respect to the above-described total light transmittance, the total light transmittance is cut out at a size of 50 mm × 100 mm, and the non-light source side is formed on the side of the hard coat layer without curling or wrinkling and without fingerprints or dust. In the manner of setting, one optical film was measured three times, and the arithmetic mean value of the value obtained by measuring three times was used. Further, as the optical film, the optical film before the above durability test was used.

<G', G", tan δ measurement>

The shear storage modulus G', the shear loss modulus G", and the shear loss tangent tan δ of the optical films of Examples A16 to A24 and Comparative Examples A3 to A6 were measured. Specifically, first, the optical film was punched out. A sample having a rectangular shape of 10 mm × 5 mm was used as a sample. Then, two samples of the sample were prepared and attached to a measurement jig of a dynamic viscoelasticity measuring device (product name "Rheogel-E4000", manufactured by UBM Co., Ltd.). Specifically, the solid shearing jig includes a metal solid shearing plate having a thickness of 1 mm and two L-shaped metal members disposed on both sides of the solid shearing plate, and a solid shearing plate and an L-shaped metal. A sample is sandwiched between the pieces, and another sample is sandwiched between the solid shear plate and the other L-shaped metal piece. In this case, the sample is sandwiched so that the resin layer becomes the solid shearing plate side and the hard coat layer becomes the L-shaped metal member side. Then, the L-shaped metal members were fastened by screws to fix the sample. Then, after the tensile test collet composed of the upper chuck and the lower chuck is attached to the dynamic viscoelasticity measuring apparatus (product name "Rheogel-E4000", manufactured by UBM Co., Ltd.), the solid shearing jig is used. The distance between the chucks is 20 mm between the upper chuck and the lower chuck. Then, the set temperature was set to 25 ° C and the temperature was raised at 2 ° C / min. In this state, the solid viscoelasticity of the solid is measured at 25 ° C while the solid shearing plate is fixed to the surface of the L-shaped metal member with a strain of 1% and a frequency of 500 Hz or more and 1000 Hz or less. The shear storage modulus G', the shear loss modulus G", and the shear loss tangent tan δ of the optical film are measured. Here, the shear storage modulus G' of the optical film in a frequency region of 500 Hz or more and 1000 Hz or less, The shear loss modulus G" and the shear loss tangent tan δ are set to values obtained by applying longitudinal vibrations of frequencies of 500 Hz, 750 Hz, and 950 Hz to the L-shaped metal members, and measuring the shear of the optical film at each frequency. Cut the storage modulus G', the shear loss modulus G" and the shear loss tangent tan δ, and find the arithmetic mean of the shear storage modulus G', the shear loss modulus G" and the shear loss tangent tan δ. Further, the measurement was repeated three times, and the three arithmetic mean values obtained separately were further arithmetically averaged. Further, as the optical film, the optical film before the above durability test was used.

<Impact resistance test>

The optical films of Examples A16 to A24 and Comparative Examples A3 to A6 were placed directly on the surface of the soda glass having a thickness of 0.7 mm so that the soda glass side became the resin layer side, and the following impact resistance test A was performed three times, that is, An iron ball having a weight of 100 g and a diameter of 30 mm was dropped from the position of 30 cm in height to the surface of the hard coat layer of the optical film. In addition, on the soda glass having a thickness of 0.7 mm, the adhesive sheet (product name "highly transparent double-sided tape 8146-2", manufactured by 3M Co., Ltd.) having a thickness of 200 μm was placed and placed on the side of the resin layer. The optical films of Examples A16 to A24 and Comparative Examples A3 to A6 were subjected to the following impact resistance test B three times, that is, an iron ball having a weight of 100 g and a diameter of 30 mm was dropped from the height of 30 cm to the hard coat layer of the optical film. surface. In addition, in the impact resistance tests A and B, the position where the iron ball is dropped is set to be changed every time. Then, in the optical film after the impact resistance test A, whether or not a depression was generated on the surface of the hard coat layer was visually evaluated, and whether or not the soda glass was cracked was evaluated. Further, in the optical film after the impact resistance test B, it was visually evaluated whether or not a depression was formed on the surface of the hard coat layer. The evaluation results are as follows.

( evaluation of the depression of the surface of the hard coat)

○: No depression was confirmed on the surface of the hard coat layer in the case where the hard coat layer was observed from the front side and the tilt side.

△: When the hard coat layer was observed from the front, no depression was observed on the surface of the hard coat layer, but in the case of oblique observation, the depression was confirmed on the surface of the hard coat layer.

×: When both cases of the hard coat layer were observed from the front side and the tilt side, significant depressions were observed on the surface of the hard coat layer.

(Evaluation of cracking of soda glass)

◎: Sodium glass was not broken.

○: Damage occurred in the soda glass but was not broken.

△: Cracking occurred in soda glass 1 to 2 times.

×: Three times, cracking occurred in soda glass.

Hereinafter, the results are shown in Tables 1 to 3.

The results will be described below. In the optical films of Comparative Examples A1 and A3 to A6, since the optical adjustment layer adjacent to the hard coat layer was not provided between the polyimide-based substrate and the hard coat layer, interference fringes were clearly observed. Further, in the optical film of Comparative Example A2, since the film thickness of the hard coat layer was thick, generation of interference fringes was suppressed, but continuous folding property was inferior. Further, in the optical film of Comparative Example A7, the first optical adjustment layer adjacent to the hard coat layer was provided between the polyimide substrate and the hard coat layer, but the film thickness of the first optical adjustment layer was higher. Thick, so continuous folding is poor. On the other hand, in the optical films of Examples A1 to A24, since the first optical adjustment layer adjacent to the hard coat layer is provided between the various base materials and the hard coat layer, generation of interference fringes is suppressed, and continuous folding property is obtained. Also excellent. Further, in the optical films of Examples A1 to A24, since the film thickness of the first optical adjustment layer was thinner than that of the optical film of Comparative Example A7, the interference film was suppressed more than the optical film of Comparative Example A7. Moreover, it was found from the evaluation of the adhesion after the heat resistance test that the optical films of Examples A1 to A11 have the second optical adjustment layer, so that the adhesion between the substrate and the first optical adjustment layer is less than that of the second optical. The optical films of Examples A12 to A24 of the adjustment layer were improved.

Further, in the optical films of Examples A1 and A8, the short side (30 mm) side of the sample which was cut by a rectangular shape of 30 mm × 100 mm was fixed in parallel so that the interval between the opposite sides of the sample was 10 mm. The fixing portion disposed in the ground was subjected to a folding standing test at 70 ° C for 12 hours in a state where the optical film was folded. Then, after the folding and standing test, the fixing portion was removed from the side portion of the one side, thereby releasing the folded state, and after 30 minutes at room temperature, the angle at which the optical film was naturally opened, that is, the opening angle was measured (refer to FIG. 3). (B)), the optical film of Example A1 had an opening angle of 100 or more, which was larger than the opening angle of the optical film of Example A8. Further, as the opening angle, the folding rest test was performed in the case where the hard coat layer was folded inside and the case where the hard coat layer was folded outward, and the angle was smaller.

Further, in the optical film of Comparative Example A3, since the film thickness of the resin layer was too small, the impact could not be absorbed, and the soda glass was broken in the impact resistance test A, and the impact resistance test B was followed. The plastic deformation of the adhesive sheet causes a large amount of depression of the surface of the hard coat layer. In the optical film of Comparative Example A4, since the film thickness of the resin layer was too thick, the folding property was inferior. In the optical film of Comparative Example A5, since the shear storage modulus G' and the shear loss modulus G" were too small, the impact could not be absorbed, and a slight crack occurred in the soda glass in the impact resistance test A. In Comparative Example A6 In the optical film, since the shear storage modulus G' is too large and the shear loss modulus G" is too small, the impact cannot be absorbed, and in the impact resistance test A, the soda glass is broken, and the folding property is also obtained. Also poor. On the other hand, in the optical films of Examples A16 to A24, since the balance between the film thickness of the resin layer, the shear storage modulus G', and the shear loss modulus G" was good, the impact resistance test could not be confirmed. The depression of the surface of the hard coat layer after A and B, and also the cracking of the soda glass.

Further, using the optical films of Examples A1 to A24 before and after the above-described durability test, samples having the same size as described above were produced, and the minimum interval between the two opposite sides of the sample was 3 mm. The sample was attached to an endurance tester (product name "DLDMLH-FS", manufactured by Yuasa System Co., Ltd.), and 10,000 times of continuous folding test was performed to fold the front side of the sample 180° (the inner side of the hard coat layer and the substrate, The third optical adjustment layer or the resin layer was folded inside (the test was folded), and the continuous folding property and the adhesion before the durability test and the continuous folding property and the adhesion after the durability test were respectively based on the same evaluation criteria as described above. As a result of the evaluation, in the optical films of Examples A1 to A15, the continuous folding property and the adhesion before the durability test and the continuous folding property and the adhesion after the durability test were good.

Further, using the optical films of Examples A1 to A24 and Comparative Examples A1 to A6 before and after the above-described durability test, samples having the same size as described above were produced, and the minimum interval between the two sides of the sample was 30 mm. In the same manner as described above, the sample was attached to an endurance tester (product name "DLDMLH-FS", manufactured by Yuasa System Co., Ltd.), and a continuous folding test (with a hard coat layer) of folding the back side of the sample by 180° was performed 10,000 times. The test for folding on the outer side and the substrate, the third optical adjustment layer or the resin layer to be inside, and the continuous folding property and the adhesion before the durability test and the durability test according to the same evaluation criteria as above The continuous folding property and the adhesion were evaluated, and as a result, the same results as in Table 1 were obtained.

Further, the Martens hardness of the optical film hard coat layer of the optical films of Examples A1 to A24 was measured, and as a result, the Martens hardness of the hard coat layer was 650 MPa. The Markov hardness was obtained by using the "TI950 TriboIndenter" manufactured by HYSITRON Co., Ltd. under the following measurement conditions, and the Berkovich indenter (triangular cone) was pressed into the center of the cross section of the hard coat layer to be fixed at 500 nm. After the relaxation of the residual stress, the load was unloaded, and the maximum load after the relaxation was measured, and the maximum load P _max (μN) and the recessed area A (nm ² ) at a depth of 500 nm were used to calculate P _max /A. The Martens hardness is an arithmetic mean of the values obtained by measuring 10 sites.

(measurement conditions)

‧Load speed: 10nm/sec

‧ Hold time: 5 seconds

‧ load unloading speed: 10nm / sec

‧Measurement temperature: 25 ° C

An antistatic agent containing a quaternary ammonium salt was applied to the surface of the polyimine-based substrate of Example A1 on the side opposite to the surface on the side of the first optical adjustment layer (product name "1SX-3000", Taisei) 100 parts by mass (100% conversion value of solid content), photopolymerization initiator (product name "Irg184", manufactured by BASF Japan Co., Ltd.), 4 parts by mass, and solvent (MIBK) 150 parts by mass of antistatic layer. The composition was coated with a composition for an antistatic layer by a bar coater to form a coating film. Then, the formed coating film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film to form an antistatic layer having a film thickness of 100 nm, thereby obtaining an optical film. Further, the front surface of the optical film is the surface of the hard coat layer, and the back surface is the surface of the antistatic layer. Then, a protective film was bonded to the front surface and the back surface of the optical film, and the peeling charge amount when the protective film was peeled off from the front surface and the back surface of the optical film was measured. As a result, the peeling charges of the front and back surfaces of the optical film were -10 kV to 10 kV, respectively. Within the scope.

<<Example B and Comparative Example B>>

<Example B1>

A polyimide substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) having a thickness of 50 μm was prepared as a light-transmitting substrate, and was applied as a first surface of one surface of a polyimide substrate by a bar coater. The composition 1 for an antistatic layer was applied to form a coating film. Thereafter, the formed coating film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film, and an ultraviolet irradiation device (manufactured by Fusion UV System Japan Co., Ltd., light source H BULB) was used in the air. The coating film was cured by irradiating ultraviolet rays so as to have an integrated light amount of 200 mJ/cm ² , and a first antistatic layer having a film thickness of 20 μm as an antistatic hard coat layer was formed. Then, the antistatic layer composition 2 was applied to the second surface of the polyimide substrate having the opposite side to the first surface by a bar coater to form a coating film. The formed coating film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film to form a second antistatic layer having a film thickness of 100 nm, and was formed on both sides of the polyimide substrate. An optical film of an antistatic layer. Further, the front surface of the optical film of Example B1 was the surface of the first antistatic layer, and the back surface was the surface of the second antistatic layer. Further, the film thickness of the antistatic layer was measured by a scanning electron microscope (SEM), and the thickness of the antistatic layer was measured in the image of the cross section, and the film of the 20 sites was used. The arithmetic mean of the thickness. In Examples B2 and B3 and Comparative Examples B1 to B3, the film thickness of the antistatic layer was also measured by the same method as in Example B1.

<Example B2>

In the same manner as in Example B1, an optical film was obtained in the same manner as in Example B1 except that the film thickness of the second antistatic layer was 10 μm. Further, the front surface of the optical film of Example B2 was the surface of the first antistatic layer, and the back surface was the surface of the second antistatic layer.

<Example B3>

A polyimide substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) having a thickness of 50 μm was prepared as a light-transmitting substrate, and was applied as a first surface of one surface of a polyimide substrate by a bar coater. The composition 2 for the hard coat layer was applied to form a coating film. Thereafter, the formed coating film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film, and an ultraviolet irradiation device (manufactured by Fusion UV System Japan Co., Ltd., light source H BULB) was used in the air. The coating film was cured by irradiating ultraviolet rays so as to have an integrated light amount of 200 mJ/cm ² to form a hard coat layer having a film thickness of 20 μm. Then, the composition 2 for the antistatic layer was applied to the surface of the hard coat layer by a bar coater to form a coating film. The formed coating film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film to form a first antistatic layer having a film thickness of 80 nm. Then, in the high-frequency sputtering apparatus, a high-frequency electric power having a frequency of 13.56 MHz and a power of 5 kW is applied to the electrode to cause discharge in the chamber, and a film thickness of 100 nm and a refractive index are formed on the surface of the first antistatic layer. It is a cerium oxide vapor-deposited layer of 1.46 as an optical adjustment layer. Thereafter, the antistatic layer composition 2 is applied to the second surface of the polyimide substrate having the opposite side to the first surface by a bar coater to form a coating film. The formed coating film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film to form a second antistatic layer having a film thickness of 80 nm, which was formed on both sides of the polyimide substrate. An optical film with an antistatic layer. Further, the front surface of the optical film of Example B3 was the surface of the ruthenium oxide vapor-deposited layer, and the back surface was the surface of the second antistatic layer.

<Comparative Example B1>

A polyimide substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) having a thickness of 50 μm was prepared as a light-transmitting substrate, and was applied as a first surface of one surface of a polyimide substrate by a bar coater. The composition 2 for the hard coat layer was applied to form a coating film. Thereafter, the formed coating film was heated at 70 ° C for 1 minute to evaporate the solvent in the coating film, and an ultraviolet irradiation device (manufactured by Fusion UV System Japan Co., Ltd., light source H BULB) was used in the air. The coating film was cured by irradiating ultraviolet rays so as to have an integrated light amount of 200 mJ/cm ² , and a hard coat layer having a film thickness of 20 μm was formed to obtain an optical film. Further, the front surface of the optical film of Comparative Example B1 was the surface of the hard coat layer, and the back surface was the surface of the polyimide substrate which was opposite to the first surface as one surface.

<Comparative Example B2>

An optical film was obtained in the same manner as in Example B1 except that the second antistatic layer was not formed in Comparative Example B2. Further, the front surface of the optical film of Comparative Example B2 was the surface of the first antistatic layer, and the back surface was the surface of the polyimide substrate opposite to the first surface.

<Comparative Example B3>

An optical film was obtained in the same manner as in Example B3 except that the second antistatic layer and the cerium oxide deposited layer were not formed in Comparative Example B3. Further, the front surface of the optical film of Comparative Example B3 was the surface of the first antistatic layer, and the back surface was the surface of the polyimide substrate opposite to the first surface.

<Anti-stripping chargeability>

The protective film was bonded to the front surface and the back surface of the optical films of Examples B1 to B3 and Comparative Examples B1 to B3, and the peeling charge amount when the protective film was peeled off from the front surface and the back surface of the optical film was measured, and the amount of peeling charge amount was evaluated. Specifically, a protective film (product name "Sunytect series", manufactured by SUN A. KAKEN Co., Ltd.) with an adhesive layer attached to the front surface and the back surface of the optical film is applied to the optical film at 23 ° C and a relative humidity of 50%. The protective film was peeled off at a peeling speed of 10 mm/sec at a peeling speed of 10 mm/sec, and was measured at a distance of 50 mm from the surface and the back surface using an electrostatic potential measuring device (product name "KSD-0103", manufactured by Kasuga Electric Co., Ltd.). The potential of the front side and the back side of the optical film was measured, and the amount of peeling charge was measured. The peeling charge amount was measured 10 times on both sides of the optical film, and the arithmetic mean value of the peeling charge amount obtained by measuring 10 times was used. The evaluation criteria are as follows.

○: The stripping power of the front and back of the optical film was in the range of 0 kV to 5 kV.

×: Any of the peeling charges of the front and back surfaces of the optical film exceeded 5 kV.

<surface resistance value>

In the optical films of Examples B1 to B3 and Comparative Examples B1 to B3, the surface resistance values of the front and back surfaces were measured under the same measurement conditions as in Example A.

<Continuous folding property>

The optical films of Examples B1 to B3 and Comparative Examples B1 to B3 were cut into a rectangular shape of 30 mm × 100 mm to prepare a sample, and the sample was attached to an endurance tester (product name "DLDMLH-FS", manufactured by Yuasa System Co., Ltd.) as follows. That is, the short side (30 mm) side of the sample is fixed by the fixing portion, and the minimum interval between the two opposite sides is 3 mm, and 100,000 times of continuous folding test for folding the front side of the sample by 180° is performed ( In the test in which the first antistatic layer, the optical adjustment layer, or the hard coat layer was inside and the second antistatic layer or the polyimide substrate was folded outward, it was examined whether or not the crack was broken or broken. Further, the optical films of Examples B1 to B3 and Comparative Examples B1 to B3 were attached to the above-mentioned endurance tester in the same manner as described above, and the back side of the sample was folded 180 times. Continuous folding test (test in which the first antistatic layer, the optical adjustment layer or the hard coat layer is formed on the outer side and the second antistatic layer or the polyimide substrate is folded inside), and whether the bent portion is not Produces cracks or breaks. The results of the continuous folding test were evaluated according to the following criteria.

○: No crack or break occurred in the bent portion in any of the continuous folding tests.

×: In any continuous folding test, cracking or fracture occurred in the bent portion.

<pencil hardness>

The front side of the optical films of Examples B1 to B3 and Comparative Examples B1 to B3 was subjected to a pencil hardness test based on JIS K5600-5-4:1999 and evaluated. The pencil hardness test was carried out by using an optical film cut out of 50 mm × 100 mm using a 2H pencil to utilize Cellotape (registered trademark) manufactured by Nichiban Co., Ltd. without bending or wrinkling on the glass plate. Fixing is performed, and in this state, the pencil is moved at a speed of 1 mm/sec while applying a load of 1 kg to the pencil. The pencil hardness test was carried out 5 times, and the front side of the optical film after the pencil hardness test was observed under a fluorescent lamp, and the damage was not observed on the surface several times in 5 times. The evaluation criteria are as follows.

○: When the pencil was 2H, no damage was observed on the surface.

×: When the pencil was 2H, the damage was visually recognized on the surface.

<saturation band voltage>

The saturation band voltages of the front and back surfaces of the optical films of Examples B1 to B3 and Comparative Examples B1 to B3 were measured under the same measurement conditions as in Example A.

<Yellow Index (YI)>

In the optical films of Examples B1 to B3 and Comparative Examples B1 to B3, the yellow index was measured and evaluated under the same conditions as in Example A. The evaluation criteria are as follows.

◎: YI did not reach 1.5.

○: YI was 1.5 or more and less than 10.0.

△: YI is 10.0 or more and 15.0 or less.

×: YI exceeds 15.0.

<Visual reflectance>

In the optical films of Examples B1 to B3 and Comparative Examples B1 to B3, the visual reflectance of light having a wavelength of 380 nm to 780 nm was measured and evaluated. The specular reflectance is measured by a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation, light source: tungsten lamp and xenon lamp), and the front side of the optical film cut into a size of 5 cm × 10 cm is irradiated at a wavelength of 380 nm. The light of ~780 nm is measured by light having a wavelength of 380 nm to 780 nm reflected from the optical film. Specifically, light having an incident angle of 5 degrees is irradiated from the front side of each optical film, and reflected light in a direction of normal reflection reflected by each optical film is received, and a reflectance in a wavelength range of 380 nm to 780 nm is measured, and thereafter, by a person A software that converts the brightness perceived by the eye (for example, a software built into the UV-2450) calculates the visual reflectance. The evaluation criteria are as follows.

◎: The visual reflectance was 3% or less.

○: The visual reflectance is more than 3% and is 10% or less.

△: The visual reflectance is more than 10% and is 15% or less.

×: The visual reflectance exceeds 15%.

The results are shown in Table 4 below.

The results will be described below. In the optical films of Comparative Examples B1 to B3, since the first antistatic layer and/or the second antistatic layer were not provided, the peeling electrification property was poor when the protective film was peeled off. On the other hand, in the optical films of the examples B1 to B3, since the first antistatic layer and the second antistatic layer are provided, the peeling electrification property is excellent when the protective film is peeled off.

Further, in the optical films of Examples B1 to B3, the short side (30 mm) side of the sample which was cut into a rectangular shape of 30 mm × 100 mm was fixed in parallel so that the interval between the opposite sides of the sample was 3 mm. The fixing portion disposed in the ground was subjected to a folding standing test at 240 ° C for 240 hours in a state where the optical film was folded. Then, after the folding and standing test, the fixing portion was removed from the side of the one side, thereby releasing the folded state, and the angle at which the optical film was naturally opened, that is, the opening angle was measured after passing for 30 minutes at room temperature, and as a result, Example B2 was obtained. The optical film has an opening angle of 100 or more, which is larger than the opening angle of the optical films of Examples B1 and B3. In addition, as the opening angle, when the first antistatic layer is folded inside and the first antistatic layer is folded outward, the folding rest test is performed, and the angle is small. By.

Further, the Martens hardness of the hard coat layer of the first antistatic layer and the third optical film of the optical films of Examples B1 and B2 was measured under the same conditions as in Example A, and as a result, the first antistatic layer and the hard coat layer were obtained. The layer has a Martens hardness of 612 MPa.

Claims (21)

 An optical film which is used for an image display device and which is foldable, and includes a resin substrate selected from the group consisting of a polyimide resin, a polyamide resin, a polyamide resin, and a resin composed of one or more of a group consisting of a polyester resin; a functional layer provided on a first surface side of the resin substrate; and a first optical adjustment layer provided on the resin substrate and Between the functional layers, and adjacent to the above functional layer.    The optical film according to claim 1, wherein the first optical adjustment layer has a refractive index lower than a refractive index of the resin substrate and higher than a refractive index of the functional layer.    The optical film according to claim 1, wherein the film thickness of the first optical adjustment layer is 30 nm or more and 200 nm or less.    The optical film according to claim 1, further comprising a second optical adjustment layer provided between the resin substrate and the first optical adjustment layer and adjacent to the resin substrate.    The optical film according to claim 1, wherein the film thickness of the second optical adjustment layer is 30 nm or more and 200 nm or less.    The optical film according to claim 1, further comprising a resin layer provided on a second surface side of the resin substrate opposite to the first surface side and having a thickness of 50 μm or more and 300 μm or less. The shear storage modulus G' of the optical film at 25 ° C and in the frequency region of 500 Hz or more and 1000 Hz or less exceeds 200 MPa and is 1200 MPa or less, and the optical film is at 25 ° C and is in a frequency region of 500 Hz or more and 1000 Hz or less. The shear loss modulus G" is 3 MPa or more and 150 MPa or less.    The optical film according to claim 1, further comprising a third optical adjustment layer provided on a second surface of the resin substrate opposite to the first surface.    The optical film according to claim 6, further comprising a third optical adjustment layer provided between the resin substrate and the resin layer and adjacent to the resin substrate.    The optical film according to claim 1, wherein the optical film has a yellow index of 15 or less.    The optical film according to claim 1, wherein the optical film is folded 180° in such a manner that the functional layer is inside and the interval between the opposite sides of the optical film is 10 mm. In the case of the test, no cracking or breaking occurs.    The optical film according to claim 1, wherein the optical film is folded 180° in such a manner that the functional layer is outside and the interval between the opposite sides of the optical film is 30 mm. In the case of the test, no cracking or breaking occurs.    An optical film which is used for an image display device and which is foldable, and includes: a light-transmitting substrate; a first antistatic layer provided on a first surface side of the light-transmitting substrate; and a second anti-corrosion The electrostatic layer is provided on the second surface side of the light-transmitting substrate opposite to the first surface.    The optical film according to claim 12, wherein the optical film has a yellow index of 15 or less.    The optical film according to claim 12, wherein the first antistatic layer is an antistatic hard coat layer.    The optical film according to claim 12, further comprising an optical adjustment layer provided on a side opposite to the light-transmitting substrate side of the first antistatic layer.    The optical film according to claim 12, further comprising a hard coat layer provided between the light-transmitting substrate and the first antistatic layer.    The optical film according to claim 12, wherein the saturated band of the front surface of the optical film is applied at a voltage of 10 kV from a front surface of the optical film at a distance of 50% at 23 ° C and a relative humidity of 50%. The absolute value of the voltage exceeds 0kV.    The optical film according to claim 12, wherein, in the case of the above-mentioned optical film, the test of folding 180° in such a manner that the interval between the opposite sides of the optical film is 3 mm is repeated 100,000 times. Produces cracks or breaks.    The optical film according to claim 12, wherein the light-transmitting substrate is a substrate composed of a polyimide-based resin, a polyamide resin, or a mixture thereof.    A collapsible image display device comprising: a display element; and the optical film according to claim 1 or 12 disposed on an observer side of the display element.    The image display device of claim 20, wherein the display element is an organic light emitting diode element.