TWI731228B - Optical film and image display device - Google Patents

Abstract

According to one aspect of the present invention, there is provided an optical film 10, which is used in an image display device and is foldable, and is provided with: a resin substrate 11, which is selected from polyimide resins and polyamide resins. The functional layer 12 is composed of one or more resins from the group consisting of imine resin, polyamide resin, and polyester resin; the functional layer 12 is provided on the first surface 11A side of the resin substrate 11; and the first The optical adjustment layer 13 is disposed between the resin substrate 11 and the functional layer 12 and is adjacent to the functional layer 12.

Description

Optical film and image display device

[Reference to related applications]

This case enjoys the priority of Japanese Special Application 2017-64583 (application date: March 29, 2017) and Japanese Special Application 2018-35426 (application date: February 28, 2018) as previous Japanese applications. The disclosure content as a whole becomes a part of this specification by quoting.

The 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 foldable image display devices are currently being developed. Generally, smart phones or tablet terminals are covered with cover glass. The glass is generally excellent in hardness but cannot be bent. Therefore, when the cover glass is used in an image display device, the risk of cracking is higher if it is folded. Therefore, for a foldable image display device, it has been studied to use a foldable optical film with a bendable resin substrate and a hard coat instead of the cover glass (for example, refer to Japanese Patent Application Laid-Open No. 2016-125063).

In such a foldable optical film, generally, the refractive index of the resin constituting the bendable resin substrate is relatively high, so the refractive index difference between the resin substrate and the hard coat layer becomes larger. Therefore, the difference in refractive index between the resin substrate and the hard coat layer may cause iridescent unevenness, that is, interference fringes.

In order to suppress the occurrence of interference fringes, there is also a method of making the film thickness of the hard coat layer thicker. However, if the film thickness of the hard coat layer is made thicker, there is a problem of cracking of the hard coat layer during folding. Therefore, the current situation is that it is impossible to obtain an optical film that is foldable and does not easily produce interference fringes.

On the other hand, with regard to this kind of optical film, dust may adhere or be damaged during the assembling step of the image display device, and the yield may be lowered. Since the base material for foldable optical film is very expensive, it is more desirable to increase the yield. In this case, there are cases where the protective film is attached to both sides of the optical film. However, the current situation is that when the protective film is peeled from the optical film, both sides of the optical film are charged, so the yield cannot be improved.

The present invention was completed in order to solve the above-mentioned problems. That is, the object of the present invention is to provide a foldable optical film that is less likely to produce interference fringes, and an image display device equipped with the foldable optical film. In addition, the object of the present invention is to provide a foldable optical film capable of improving the yield of the assembling step of the image display device, and an image display device provided with the foldable optical film.

According to one aspect of the present invention, there is provided an optical film which is used in an image display device and is foldable, and is provided with: a resin substrate, which is selected from the group consisting of polyimide resins and polyimide imines Composed of one or more resins from the group consisting of a polyamide 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 above-mentioned resin base material and the above-mentioned functional layer, and is adjacent to the above-mentioned functional layer.

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

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

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 the film thickness is 50 μm or more and 300 μm or less, the optical film The shear storage modulus G'at 25℃ and above 500Hz and below 1000Hz in the frequency region exceeds 200MPa and below 1200MPa, and the above-mentioned optical film is sheared at 25℃ and above 500Hz and below 1000Hz in the frequency region The loss modulus G" is 3 MPa or more and 150 MPa or less.

The above-mentioned optical film may further include a third optical adjustment layer provided on the second surface of the resin substrate on the opposite side to the first surface.

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-mentioned optical film, the yellow index of the above-mentioned optical film may be 15 or less.

In the above-mentioned optical film, it is preferable that no cracks or cracks occur when the test is repeated 10,000 times when the functional layer becomes the inner side and the distance between the opposing sides of the optical film becomes 10mm. fracture.

In the above-mentioned optical film, it is preferable that no cracks or cracks occur when the test is repeated 10,000 times when the functional layer becomes the outer side and the distance between the opposing sides of the optical film becomes 30mm. fracture.

According to another aspect of the present invention, there is provided an optical film, which is used in an image display device and is foldable, and includes: a light-transmitting substrate; and a first antistatic layer disposed on the light-transmitting substrate The first surface side; and the second antistatic layer, which is provided on the second surface side of the translucent substrate opposite to the first surface.

In the above-mentioned optical film, the yellow index of the above-mentioned optical film may be 15 or less.

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

The optical film may further include an optical adjustment layer provided on the side opposite to the translucent substrate side of the first antistatic layer.

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

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

In the above-mentioned optical film, it is preferable that no cracks or breaks occur when the test is repeated 100,000 times by folding 180° so that the distance between the opposing sides of the above-mentioned optical film becomes 3 mm.

In the above-mentioned optical film, the above-mentioned translucent substrate may be a substrate composed of a polyimide-based resin, a polyamide-based resin, or a mixture of these.

According to another aspect of the present invention, there is provided a foldable image display device, which is characterized by comprising: a display element; and the above-mentioned optical film, which is disposed on the side of the observer more than the display element.

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

According to one aspect of the present invention, it is possible to provide a foldable optical film that does not easily produce interference fringes. Furthermore, according to another aspect of the present invention, it is possible to provide a foldable optical film capable of improving the yield of the assembling step of the image display device. Furthermore, according to another aspect of the present invention, an image display device provided with 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‧‧‧Front

11‧‧‧Resin substrate

11A‧‧‧Side 1

11B‧‧‧Side 2

12‧‧‧Functional layer

13‧‧‧The first optical adjustment layer

14‧‧‧Second optical adjustment layer

15‧‧‧The third optical adjustment layer

80、110‧‧‧Video display device

83‧‧‧Display element

92、103‧‧‧The first antistatic layer

93、105‧‧‧Second antistatic layer

102‧‧‧Hard coating

104‧‧‧Optical adjustment layer

Fig. 1 is a schematic configuration diagram of the optical film of the first embodiment.

Fig. 2(A)~Fig. 2(C) are diagrams schematically showing the situation of the continuous folding test.

Fig. 3(A) and Fig. 3(B) are diagrams schematically showing the state of the folding static 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.

Figure 8 is a schematic diagram of the solid shearing fixture used to measure the shear storage modulus G'and the shear loss modulus G".

Fig. 9 is a schematic configuration diagram of the image display device of the first embodiment.

Fig. 10 is a schematic configuration diagram of the optical film of the 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 the image display device of the second embodiment.

[First Embodiment]

Hereinafter, the optical film and the image display device of the first embodiment of the present invention will be described with reference to the drawings. In this manual, terms such as "membrane" and "sheet" are not distinguished from each other only based on the difference in title. Therefore, for example, "membrane" is used in the meaning of also including a member such as a sheet. Fig. 1 is a schematic configuration diagram of the optical film of this embodiment, Fig. 2(A) ~ Fig. 2(C) are diagrams schematically showing the state of continuous folding test, Fig. 3(A) and Fig. 3(B) are A diagram schematically showing the state of the folding and standing test. Figures 4 to 7 are schematic diagrams of other optical films of the embodiment, and Figure 8 is a schematic diagram of solid shearing jigs used when 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 image display devices, and is foldable.

The optical film 10 includes: a resin substrate 11; a functional layer 12 provided on the side of the first surface 11A which is one surface of the resin substrate 11; and a first optical adjustment layer 13 (hereinafter, sometimes abbreviated as "optical adjustment layer 13″), which is disposed between the resin substrate 11 and the functional layer 12 and is adjacent to the functional layer 12. The optical film 10 shown in FIG. 1 is further provided with: 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 and adjacent to the resin substrate 11; and the third optical adjustment layer 15 (hereinafter, sometimes referred to as "optical adjustment layer 15"), which is provided as the resin substrate 11 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. In addition, the optical film 10 may further include a resin layer on the second surface 11B side of the resin base material 11 as shown in the following optical film 40. The "functional layer" in this specification refers to a layer intended to perform certain functions in an optical film. Specifically, as a functional layer, a hard coat layer, an antistatic layer, an antifouling layer, etc. are mentioned, for example. The functional layer 12 functions as a hard coat layer. In addition, the functional layer 12 has a single-layer structure, but the functional layer may not only have a single-layer structure, but may also have a multilayer structure of two or more layers. In addition, each "optical adjustment layer" in this specification has a single-layer structure, not a multilayer structure of two or more layers. Furthermore, in FIG. 1, two optical adjustment layers of a first optical adjustment layer 13 and a second optical adjustment layer 14 are provided between the resin substrate 11 and the functional layer 12, and the first optical adjustment layer 13 and Further, other optical adjustment layers and the like are 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. Furthermore, in this specification, the front surface of the optical film is used in the meaning of the surface of one side of the optical film, so the surface opposite to the front surface of the optical film is called the back surface to distinguish it from the front surface of the optical film. The back surface 10B of the optical film 10 becomes the surface 15A on the opposite side of the surface of the optical adjustment layer 15 and the resin base material 11 side.

The optical film 10 is foldable. Specifically, it is preferable to continuously fold the optical film 10 (continuous folding test) so that the functional layer 12 becomes the inner side and the distance between the opposing sides of the optical film 10 becomes 10 mm even after repeated 10,000 times. In this case, the optical film 10 will not be cracked or broken, and it is more preferable that the optical film 10 will not be cracked or broken even when the continuous folding test is repeated 20,000 times. The optical film 10 will not crack or break even when it is repeated 100,000 times. When the optical film 10 is repeatedly subjected to a continuous folding test 10,000 times, if cracks or the like occur in the optical film 10, the foldability of the optical film 10 becomes insufficient. In addition, it is preferable to continuously fold the optical film 10 (continuous folding test) even after repeatedly performing the test (continuous folding test) of the optical film 10 so that the functional layer 12 becomes the outside and the distance between the opposing sides of the optical film 10 becomes 30 mm. When the optical film 10 is not cracked or broken, it is more preferable that the optical film 10 is not cracked or broken even when the continuous folding test is repeated 20,000 times. The optical film 10 will not be cracked or broken even when it is performed 100,000 times.

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 facing the side portion 10C are respectively fixed by the fixing portions 20 arranged in parallel. Furthermore, the optical film 10 can have any shape, but the optical film 10 in the continuous folding test is preferably a rectangle (for example, a rectangle of 30 mm×100 mm). In addition, as shown in FIG. 2(A), the fixed portion 20 can slide in the horizontal direction.

Next, as shown in FIG. 2(B), by moving the fixing portion 20 close to each other, the functional layer 12 becomes the inner side, that is, the front surface 10A of the optical film 10 becomes the inner side and the optical film 10 is folded. Furthermore, as shown in FIG. 2(C), after the fixed portion 20 is moved to a position where the distance between the two opposing sides fixed by the fixed portion 20 of the optical film 10 becomes 10 mm, the fixed portion 20 is moved in the opposite direction. The deformation of the optical film 10 is released.

By moving the fixed portion 20 as shown in FIGS. 2(A) to (C), the optical film 10 can be folded by 180°. In addition, a continuous folding test was performed so that the curved portion 10E of the optical film 10 did not protrude from the lower end of the fixing portion 20, and the interval when the fixing portion 20 was closest to each other was controlled to 10 mm, so that the optical film 10 could be aligned with each other. The distance between the two sides is 10mm. In this case, the outer diameter of the curved portion 10E is regarded as 10 mm. Furthermore, the thickness of the optical film 10 is a sufficiently small value compared to the interval (10 mm) of the fixing portion 20, so it can be considered that the result of the continuous folding test of the optical film 10 is not affected by the difference in the thickness of the optical film 10 . In the optical film 10, it is more preferable not to repeatedly perform a continuous folding test of 180° with the functional layer 12 as the inner side and the distance between the opposing sides of the optical film 10 as 10 mm. Cracks or breaks occur, and it is best that no breaks occur when the continuous folding test is repeated 10,000 times with the functional layer 12 as the inside and the distance between the opposing edges of the optical film 10 at 2 mm. Or break.

In the optical film 10, as shown in FIG. 3(A), the side 10C of the optical film 10 and the side 10D facing the side 10C are used so that the distance between the side 10C and the side 10D becomes 10 mm In the state where the fixed parts 25 arranged in parallel are respectively fixed and the optical film 10 is folded, a folding static test is performed at 70°C for 12 hours, as shown in Fig. 3(B). The part 10D removes the fixing part 25 and releases the folded state. When the optical film 10 is measured for the optical film 10 after 30 minutes at room temperature, the opening angle θ of the optical film 10 is preferably the optical film 10 The opening angle θ is more than 100°. Furthermore, the larger the opening angle θ, the better the restorability, and the maximum is 180°. The folding and standing test can be carried out as if the optical film 10 is folded with the functional layer 12 on the inside, or can be carried out as if the optical film 10 is folded with the functional layer 12 on the outside, preferably in either case, The opening angle θ is all 100° or more.

Regarding the front surface 10A of the optical film 10 (the front surface 12A of the functional layer 12), the hardness (pencil hardness) when measured by the pencil hardness test specified in JIS K5600-5-4: 1999 is preferably 3H or more, more preferably Above 4H. The pencil hardness test is performed by using Cellotape (registered trademark) manufactured by Nichiban Co., Ltd. without bending or wrinkles on the optical film 10 cut out with a size of 30mm×100mm. Fixed, using a pencil hardness tester (product name "Pencil scratch coating film hardness tester (electric type)", manufactured by Toyo Seiki Seisakusho Co., Ltd.) for the front of the optical film, and a pencil (product name "Uni") , Mitsubishi Pencil Co., Ltd.) While applying a load of 750g, the pencil moves at a moving speed of 1mm/sec. The pencil hardness is set to the highest hardness that does not cause damage to the front surface of the optical film in the pencil hardness test. In addition, when measuring the pencil hardness, use multiple pencils with different hardness to perform the pencil hardness test 5 times for each pencil, and judge if the front surface of the optical film is damaged 4 times out of 5 times. The pencil of this hardness damages the front surface of the optical film. The above-mentioned damage refers to the visually recognized by penetrating observation of the front surface of the optical film subjected to the pencil hardness test under a fluorescent lamp.

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

In the optical film 10, in an environment of 23°C and a relative humidity of 50%, the saturated charge voltage of the front surface of the optical film 10 when a voltage of 10kV is applied at a distance of 50mm from the front surface of the optical film 10 at a distance of 10A (saturated charge voltage) ) Is preferably more than 0kV. Also, similarly, the saturation band voltage of the back surface 10B of the optical film 10 when a voltage of 10kV is applied from the back surface 10B of the optical film 10 at a distance of 20 mm from the back surface 10B of the optical film 10 is preferably more than 0kV under the environment of 23°C and 50% relative humidity. . The so-called saturated charge voltage refers to the maximum voltage that the optical film can store. When an optical film with an antistatic hard coating is arranged on the observer side more than the touch sensor, the position detection of the finger of the touch sensor cannot be performed due to the antistatic hard coating. However, if the saturation band voltage of the front surface 10A of the optical film 10 exceeds 0kV, even when the optical film 10 is placed on the side of the observer relative to the touch sensor, touch sensing can be used The position detection of the finger of the device. The saturated charged voltage can be measured using a charged charge decay tester (product name "H-0110", manufactured by Shishido Electrostatic). The saturation band voltage is set as the arithmetic average of the values obtained by measuring 3 times on an optical film cut out with a size of 100mm×100mm. The lower limit of the saturation band voltage is more 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. If the YI of the optical film 10 is 15 or less, the yellow tint 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 as follows: the back side of the optical film cut out with a size of 50mm×100mm is placed on the spectrophotometer (product name "UV-2450", Shimadzu) so that the back side of the optical film becomes the light source side Manufactured by the Mfg. Co., light source: tungsten lamp and deuterium lamp), according to the measured transmittance of the optical film in this state with a wavelength of 300nm~780nm, according to the calculation formula described in JIS Z8722:2009, calculate the chromaticity three The stimulus values X, Y, and Z are calculated from the tristimulus values X, Y, and Z according to the calculation formula 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 above-mentioned yellow index (YI) is measured 3 times for one optical film, and the arithmetic average of the values obtained by the 3 measurements is used. Furthermore, in the UV-2450, the yellow index is calculated by reading the measurement data of the above-mentioned transmittance on the monitor connected to the UV-2450, and checking the "YI" item in the calculation item. The transmittance of wavelength 300nm~780nm is determined by the following method, namely, under the following conditions, measure the transmittance of the lowest 5 points between the wavelength of 300nm~780nm and 1nm before and after the wavelength, and calculate the average value. In addition, if there are fluctuations in the spectrum of the spectral transmittance, smoothing can also be performed at δ5.0nm.

(Measurement conditions)

‧Wavelength range: 300nm~780nm

‧Scan 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

‧Auto-return to zero: after scanning the baseline, implement at 550nm

In order to adjust the yellow index (YI) of the optical film 10, for example, at least any one of the resin substrate 11, the functional layer 12, and the optical adjustment layers 13, 14 may contain a blue pigment that becomes a complementary color of yellow. Even when the yellow tint becomes a problem due to the use of a polyimide-based substrate as a resin substrate, the yellow index (YI) of the optical film can be lowered by making the resin substrate 11 and the like contain a blue pigment. .

The blue pigment 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 preferably one having both light resistance and heat resistance. As the above-mentioned blue pigments, polycyclic organic pigments or metal complex organic pigments, etc., compared with the molecular dispersion of dyes, the degree of molecular cleavage caused by ultraviolet rays is smaller, and the light resistance is particularly excellent, so it is required for light resistance, etc. The use is preferable, and more specifically, phthalocyanine-based organic pigments and the like can be preferably cited. However, since the pigment generates particle dispersion in the solvent, there is an obstacle to transparency caused by particle scattering. Therefore, it is preferable that the particle size of the pigment dispersion is located in the Rayleigh scattering region. On the other hand, when the transparency of the optical film is important, it is preferable to use a dye that generates molecular dispersion in a solvent as the blue pigment. In addition, inorganic pigments such as cobalt blue can also be used as the blue pigment.

From the side of the optical adjustment layer 15 toward the optical film 10, irradiate light with a continuous spectrum in the wavelength range from 300 nm to 780 nm at an incident angle of 0°, and obtain the L ^* a of the light (transmitting light) penetrating the optical film 10 ^* b ^* represents the color coordinates a ^* and b ^* of the color system. In this case, it is preferable that a ^* is -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 within the above ranges, the yellow index can be made 15 or less. The measurement of a ^* and b ^* can be performed using a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation). As the light source, a tungsten halogen (WI) lamp alone, or a combination of a deuterium (D2) lamp and a tungsten halogen (WI) lamp can be cited. In this specification, the "light with an incident angle of 0°" refers to the light in the normal direction when the normal direction of the first surface of the optical film is set to 0°. "L ^* a ^* b ^* color system", "a ^* " and "b ^* " are based on JIS Z8729:2004.

The spectral transmittance of the optical film 10 at a wavelength of 380 nm is preferably 8% or less. If the above-mentioned spectral transmittance of the optical film exceeds 8%, when the optical film is used in a mobile terminal, the polarizing element may be easily degraded when exposed to ultraviolet rays. The above-mentioned transmittance can be measured using a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation). The measurement conditions of the above-mentioned spectral transmittance are the same as the above-mentioned measurement conditions of the spectral transmittance with a wavelength of 300nm~780nm. The above-mentioned transmittance is measured 3 times for an optical film cut out with a size of 50mm×100mm, and the arithmetic average of the values obtained by the 3 measurements is used. The upper limit of the above-mentioned transmittance of the optical film 10 is more preferably 5%. Furthermore, the above-mentioned transmittance of the optical film 10 can be achieved by adjusting the addition amount of the following ultraviolet absorber and 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 over 85%, sufficient image visibility can be obtained when the optical film 10 is used in a mobile terminal. The total light transmittance of the optical film 10 is more preferably 87% or more, and most preferably 90% or more.

，故而需要如直徑成為21mm以上之樣品大小。因此，亦可以22mm×22mm以上之大小適當切出光學膜。於光學膜之大小較小之情形時，於不偏離光源點之範圍內略微地偏移、或改變角度等而將測定點設為3個部位。 The above-mentioned total light transmittance can be measured using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Research Institute Co., Ltd.) by a method based on JIS K7361-1:1997. The above-mentioned total light transmittance is obtained by cutting out the optical film in a size of 50mm×100mm and setting it in a state without curls or wrinkles and no fingerprints or dust. The measurement is performed 3 times for one optical film, and the measurement is performed 3 times. And the arithmetic mean of the obtained value. The "measurement 3 times" in this manual does not measure the same part 3 times, but means measuring 3 different parts. In the optical film 10, the visual front side 10A is flat, and the laminated layers such as the functional layer 12 are also flat, and the unevenness of the film thickness is also within the range of ±10%. Therefore, it is considered that by measuring the total light transmittance at three different parts of the cut optical film, the average value of the total light transmittance in the entire surface of the optical film can be obtained. Regardless of whether the measuring object is a length of 1m×3000m, or the size of a 5 inch smartphone, the variation of total light transmittance is within ±10%. Furthermore, when the optical film is not cut out in the above-mentioned size, for example, because the entrance opening of the HM-150 measurement is 20mm

, So the sample size must be 21mm or more in diameter. Therefore, it is also possible to appropriately cut out the optical film with a size of 22mm×22mm or more. When the size of the optical film is small, slightly shift or change the angle within the range that does not deviate from the light source point, and set the measurement points to 3 locations.

The haze value (total haze value) of the optical film 10 is preferably 2.5% or less. If the above-mentioned haze value of the optical film is 2.5% or less, when the optical film is used in a mobile terminal, the whitening of the image display surface can be suppressed. The above-mentioned haze value is more preferably 1.5% or less, and more preferably 1.0% or less.

，故而需要如直徑成為21mm以上之樣品大小。因此，亦可以22mm×22mm以上之大小適當切出光學膜。於光學膜之大小較小之情形時，於不偏離光源點之範圍內略微地偏移、或改變角度等而將測定點設為3個部位。 The above-mentioned haze value can be measured by a method based on JIS K7136:2000 using a haze meter (product name "HM-150", manufactured by Murakami Color Research Institute Co., Ltd.). The above haze value is obtained by cutting the optical film to a size of 50mm×100mm and setting it in a state without curls or wrinkles and no fingerprints or dust, etc., and measured 3 times for one optical film, and obtained by measuring 3 times The arithmetic mean of the value. In the optical film 10, the visual front side 10A is flat, and the laminated layers such as the functional layer 12 are also flat, and the unevenness of the film thickness is also within the range of ±10%. Therefore, it is considered that by measuring the haze value at three different locations of the cut optical film, the average value of the haze value of the entire optical film can be obtained roughly. Regardless of whether the measuring object is a length of 1m×3000m, or the size of a 5 inch smartphone, 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, because the entrance opening of the HM-150 measurement is 20mm

, So the sample size must be 21mm or more in diameter. Therefore, it is also possible to appropriately cut out the optical film with a size of 22mm×22mm or more. When the size of the optical film is small, slightly shift or change the angle within the range that does not deviate from the light source point, and set the measurement points to 3 locations.

When another film such as a polarizing plate is provided on the first surface side of the optical film 10 through the adhesive layer or the adhesive layer, after peeling off the other film together with the adhesive layer or the adhesive layer, perform a folding test, a folding static test, Yellow index measurement, total light transmittance measurement, haze value measurement. The peeling of other films can be performed in the following manner, for example. First, use a dryer to heat the laminate with other films attached to the optical film through the adhesive layer or the adhesive layer, cut into the tip of the cutter at the interface between the optical film and the other film, and slowly peel it off. By repeatedly performing such heating and peeling, the adhesive layer or adhesive layer and other films can be peeled off. Furthermore, even if there is such a peeling step, it will not have a great influence on the tests or the measurements. The haze value is measured after the adhesive layer or the adhesive layer is peeled off, and then the stains of the adhesive layer or the adhesive layer are thoroughly wiped with alcohol.

In recent years, Light Emitting Diodes have been actively used as the light source of the backlight of image display devices such as personal computers or tablet terminals, but the light emitting diodes emit strong light called blue light. It is known that the blue light is light with a wavelength of 380nm~495nm and has properties close to ultraviolet rays. It has strong energy, so it will not be absorbed by the cornea or lens and reach the retina, thereby causing retinal damage, eye fatigue, and poor sleep. Causes of influence, etc. Therefore, it is preferable that when the optical film is applied to an image display device, the color tone of the display screen is not affected, and the blue light shielding property is excellent. Therefore, from the viewpoint of blocking blue light, the optical film 10 preferably has a spectral transmittance of less than 1% at a wavelength of 380nm, a spectral transmittance of less than 10% at a wavelength of 410nm, and a spectral transmittance of 70% at a wavelength of 440nm. the above. The reason is that if the above-mentioned spectral transmittance at a wavelength of 380nm is more than 1%, or the spectral transmittance at a wavelength of 410nm is more than 10%, the problem caused by blue light cannot be solved. If the transmittance is less than 70%, it may affect the color tone of the display screen of the image display device using the optical film. The optical film 10 can fully absorb light in the wavelength region below 410 nm in the wavelength of blue light. On the other hand, it can fully penetrate light above 440 nm without affecting the color tone of the display screen. The blue light has excellent shielding properties. In addition, when the optical film 10 with excellent blue light shielding properties is applied to an organic light emitting diode (OLED) display device as an image display device, it is also effective for suppressing the deterioration of the organic light emitting diode device.

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

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

The optical film 10 preferably uses the least square method to obtain a transmission spectrum with a wavelength ranging from 415 nm to 435 nm and the slope of the transmission spectrum is greater than 2.0. If the above-mentioned slope is 2.0 or less, in the blue light wavelength region, for example, in the wavelength region of 415 to 435 nm, the light cannot be sufficiently cut off, and the blue light cutoff effect may be weakened. In addition, considering the possibility of excessively cutting off the blue light wavelength region (wavelength 415~435nm), in this case, there is a backlight or light-emitting wavelength region of the image display device (for example, light emission from OLED with a wavelength of 430nm) A situation where the possibility of undesirable conditions such as interference and color deterioration becomes greater. For example, the above slope can be measured by using a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation) that can be measured every 0.5 nm, and the transmittance at the lowest 5 points between 415~435nm and 1nm before and after can be measured. Calculated based on the data.

The blue light shielding rate of the optical film 10 is preferably 40% or more. If the blue light shielding rate is less than 40%, it may not fully solve the above-mentioned problems caused by blue light. The above-mentioned blue light shielding rate is a value calculated by JIS T7333:2005, for example. In addition, such a blue light shielding rate can be achieved by, for example, making the functional layer 12 contain the following sesamol-type benzotriazole-based monomer.

The use of the optical film 10 is not particularly limited. Examples of the use of the optical film 10 include: smart phones, tablet terminals, personal computers (PCs), wearable terminals, digital signage, televisions, car navigation and other image display devices. In addition, the optical film 10 is also suitable for in-vehicle use. As the form of each of the above-mentioned image display devices, it is also preferable for applications requiring flexibility such as foldability and curling.

The optical film 10 can be cut into a desired size or can be rolled. When the optical film 10 is cut into a desired size, the size of the optical film is not particularly limited, and can be appropriately determined according to 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. The term "inch" in this manual refers to the length of the diagonal when the optical film is in a quadrangular shape, refers to the diameter in the case of a circular shape, and refers to the short diameter and the length in the case of an elliptical shape. The average of the sum of the paths. Here, when the optical film has a quadrangular shape, the aspect ratio of the optical film at the time of obtaining the above-mentioned inches is not particularly limited as long as there is no problem as the display screen of the image display device. For example, vertical: horizontal=1:1, 4:3, 16:10, 16:9, 2:1, etc. can be listed. Among them, it is not limited to this aspect ratio, especially in vehicle-mounted applications or digital signage with rich design. In addition, when the size of the optical film 10 is large, it is cut out in an A5 size (148mm×210mm) from an arbitrary position, and then cut out in the size of each measurement item.

The location of the optical film 10 in the image display device can 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 an image display device, the optical film 10 functions as a cover film used instead of cover glass.

<<Resin substrate>>

The resin substrate 11 has translucency. The "transmittance" in this specification refers to the property that allows light to pass through, for example, including the total light transmittance of 50% or more, preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more. The so-called light transmittance does not necessarily need to be transparent, and may be translucent.

The resin substrate 11 is selected from polyimide resins, polyimide resins, polyamide resins, and polyester resins (e.g., polyethylene terephthalate resin or polyethylene naphthalate resin). A base material composed of one or more resins in the group consisting of ethylene formate resin.

Among these resins, not only are they not easy to crack or break in the continuous folding test, but they also have excellent hardness and transparency, and also have excellent heat resistance. They can also be calcined to give more excellent hardness and transparency. From the viewpoint of performance, a polyimide-based resin, a polyimide-based resin, or a mixture of these is preferred.

The polyimide resin is obtained by reacting a tetracarboxylic acid component and a diamine component. The polyimide resin is not particularly limited. For example, in terms of having 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 structure in the group consisting of the structure represented by ).

In the above general formula (1), R ¹ represents a tetravalent group as a tetracarboxylic acid residue, and R ² represents selected from trans-cyclohexanediamine residues, trans-1,4-bismethylene Cyclohexane diamine residue, 4,4'-diaminodiphenyl sulfonate residue, 3,4'-diaminodiphenyl sulfonate residue, and the two represented by the following general formula (2) At least one divalent group in the group consisting of valence groups. n represents the number of repeating units, and is 1 or more. In this specification, the "tetracarboxylic acid residue" refers to the residue after removing 4 carboxyl groups from tetracarboxylic acid, and means the same structure as the residue after removing the acid dianhydride structure from tetracarboxylic dianhydride. In addition, the "diamine residue" refers to a residue obtained by removing two amine groups from a diamine.

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

In the above general formula (3), R ⁵ represents selected from cyclohexane tetracarboxylic acid residue, cyclopentane tetracarboxylic acid residue, dicyclohexane-3,4,3',4'-tetracarboxylic acid Residues and at least one tetravalent group in the group consisting of 4,4'-(hexafluoroisopropylidene) diphthalic acid residues, 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 general formula (1) is a tetracarboxylic acid residue, which can be the residue obtained by removing the acid dianhydride structure from the tetracarboxylic dianhydride as exemplified above. ^{As R 1} in the above general formula (1), it is preferable to contain 4,4'-(hexafluoroisopropylidene) diphthalic acid in terms of improving light transmittance and increasing rigidity. Residues, 3,3',4,4'-biphenyltetracarboxylic acid residues, pyromellitic acid residues, 2,3',3,4'-biphenyltetracarboxylic acid residues, 3,3',4,4'-benzophenone tetracarboxylic acid residue, 3,3',4,4'-diphenyl tetracarboxylic acid residue, 4,4'-oxydiphthalic acid residue, At least one of cyclohexanetetracarboxylic acid residues and cyclopentanetetracarboxylic acid residues, and more preferably contains 4,4'-(hexafluoroisopropylidene) di-ortho At least one of phthalic acid residues, 4,4'-oxydiphthalic acid residues, and 3,3',4,4'-diphenyl tetracarboxylic acid residues.

In R ¹ , the total content of these preferable residues is preferably 50 mol% or more, more preferably 70 mol% or more, and still more preferably 90 mol% or more.

In addition, as R ¹ , it is also preferable to select from 3,3',4,4'-biphenyltetracarboxylic acid residues, 3,3',4,4'-benzophenonetetracarboxylic acid residues At least one of the group consisting of pyromellitic acid residues and tetracarboxylic acid residues suitable for improving rigidity (group A), and such as selected from 4,4'-(hexafluoroisocyanide Propyl) diphthalic acid residues, 2,3',3,4'-biphenyltetracarboxylic acid residues, 3,3',4,4'-diphenyl tetracarboxylic acid residues, 4 ,4'-oxydiphthalic acid residue, cyclohexane tetracarboxylic acid residue, and cyclopentane tetracarboxylic acid residue at least one of the group consisting of tetracarboxylic acid suitable for improving transparency The residue group (group B) is mixed and used.

In this case, the content ratio of the above-mentioned tetracarboxylic acid residue group suitable for improving rigidity (group A) and the tetracarboxylic acid residue group suitable for improving transparency (group B) is relative to that suitable for improving transparency The group of tetracarboxylic acid residues (group B) is 1 mol, and the group of tetracarboxylic acid residues (group A) suitable for improving 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, more preferably 0.3 mol or more and 4 mol or less.

^{As R 2} in the above general formula (1), among them, in terms of improving light transmittance and increasing rigidity, it is preferably selected from 4,4'-diaminodiphenyl sulfonium residues, 3,4 '-Diaminodiphenyl sulfide residues and at least one divalent group in the group consisting of the divalent group represented by the general formula (2), and more preferably selected from 4,4'-di Amino diphenyl sulfonate residue, 3,4'-diamino diphenyl sulfonate residue, and R ³ and R ⁴ are perfluoroalkyl groups and are composed of the divalent group represented by the above general formula (2) At least one divalent group in the group.

^{As R 5} in the above general formula (3), it is preferable to contain 4,4'-(hexafluoroisopropylidene) diphthalic acid residues in terms of improving light transmittance and increasing rigidity , 3,3',4,4'-diphenyl tetracarboxylic acid residues, and oxydiphthalic acid residues.

In R ⁵ , the preferable residues preferably contain 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

^{R 6} in the above general formula (3) is a diamine residue, which can be a residue obtained by removing two amine groups from the diamine as exemplified above. ^{As R 6} in the above general formula (3), among them, it is preferable to contain a residue selected from 2,2'-bis(trifluoromethyl)benzidine, in terms of improving light transmittance and increasing rigidity, Bis[4-(4-aminophenoxy)phenyl] residues, 4,4'-diaminodiphenyl residues, 2,2-bis[4-(4-aminophenoxy) Yl)phenyl]hexafluoropropane residues, bis[4-(3-aminophenoxy)phenyl]sulfonate residues, 4,4'-diamino-2,2'-bis(trifluoromethane) Yl)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 formaniline residues, N,N'-bis(4-aminophenyl) p-xylylenedimethamide residues, and 9,9-bis(4-aminophenyl) residues At least one kind of divalent group among them, and more preferably contains a residue selected from 2,2'-bis(trifluoromethyl)benzidine, bis[4-(4-aminophenoxy)phenyl] sulfide Residues and at least one divalent group in the group consisting of 4,4'-diaminodiphenyl sulfonate residues.

In R ⁶ , the total content of these preferable residues is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

In addition, as R ⁶ , it is also preferable to select from the group consisting of bis[4-(4-aminophenoxy)phenyl] sulfide residues, 4,4'-diaminobenzylaniline residues, N , N'-bis(4-aminophenyl)p-xylylenediamine residues, p-phenylenediamine residues, m-phenylenediamine residues, and 4,4'-diaminodiphenylmethane residues At least one diamine residue group (group C) suitable for improving rigidity among the group consisting of the group, and as selected from 2,2'-bis(trifluoromethyl)benzidine residue, 4, 4'-diaminodiphenyl residues, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane residues, bis[4-(3-aminophenoxy) Yl)phenyl]sulfuryl 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 and at least one of the group consisting of 9,9-bis(4-aminophenyl) residue is suitable for improving transparency The sex diamine residue group (group D) is mixed and used.

In this case, the content ratio of the above-mentioned diamine residue group suitable for improving rigidity (group C) and the diamine residue group suitable for improving transparency (group D) is relative to the content ratio suitable for improving transparency The diamine residue group (group D) is 1 mol, and the above-mentioned diamine residue group (group C) suitable for improving 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, more preferably 0.3 mol or more and 4 mol or less.

In the structures represented by the above-mentioned general formula (1) and the above-mentioned general 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 polyimide is not particularly limited as long as it is appropriately selected according to the structure so as to represent the following preferable glass transition temperature. The average number of repeating units is usually 10 to 2000, and more preferably 15 to 1000.

In addition, the polyimide-based resin may contain a polyimide structure in a part thereof. As the polyamide structure that can be contained, for example, a polyamide imide structure containing tricarboxylic acid residues such as trimellitic anhydride, or a polyamide containing dicarboxylic acid residues such as terephthalic acid can be cited. Amine structure.

In terms of heat resistance, the glass transition temperature of the polyimide resin is preferably 250°C or higher, and more preferably 270°C or higher. On the other hand, the glass transition temperature is preferably 400°C or lower, and more preferably 380°C or lower, in terms of ease of stretching or lowering of the baking temperature.

As the polyimide resin, for example, a compound having a structure represented by the following formula can be cited. In the following formula, n is a repeating unit and represents an integer of 2 or more.

Among the above-mentioned polyimide-based resins, in terms of excellent transparency, a polyimide-based resin or a polyimide-based resin having a structure that does not easily cause charge transfer within or between molecules is preferred Specifically, fluorinated polyimide resins such as the above formulas (4) to (11), and polyimide resins having an alicyclic structure such as the above formulas (13) to (16) can be cited.

In addition, in fluorinated polyimide resins such as the above formulas (4) to (11), due to the fluorinated structure, it has high heat resistance and is not affected by polyimide resins. The polyimide film of the composition is colored by the heat during manufacture, so it has excellent transparency.

The concept of polyamide resins includes not only aliphatic polyamides, but also aromatic polyamides (aramid). As a polyamide resin, the compound which has a skeleton represented by following formula (21)-(23) is mentioned, for example. In addition, in the following formula, n is a repeating unit and represents an integer of 2 or more.

The base material composed of the polyimide-based resin or the polyimide-based resin represented by the above formulas (4) to (20) and (23) may also be commercially available. As a commercially available product of a substrate composed of the above-mentioned polyimide-based resin, for example, Neopulim manufactured by Mitsubishi Gas Chemical Co., Ltd., etc. can be cited. As a commercially available product of a substrate composed of the above-mentioned polyimide-based resin, for example, Examples include Mictron manufactured by Toray Corporation.

In addition, the polyimide-based resin or polyimide-based resin represented by the above formulas (4) to (20) and (23) can also be synthesized by a known method. For example, the method for synthesizing the polyimide-based resin represented by the above formula (4) is described in JP 2009-132091. Specifically, it can be obtained by using 4,4'-hexa represented by the following formula (24) It is obtained by reacting fluoropropylene bisphthalic dianhydride (FPA) with 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB).

The weight average molecular weight of the polyimide resin or polyimide 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 200,000 or less The scope. If the weight average molecular weight is less than 3,000, sufficient strength may not be obtained. If it exceeds 500,000, the viscosity will increase and the solubility will decrease. Therefore, it may not be possible to obtain a substrate with a smooth surface and a uniform film thickness. In addition, in this specification, the "weight average molecular weight" refers to a polystyrene conversion value measured by gel permeation chromatography (GPC).

From the viewpoint of improving the hardness, the resin substrate 11 is preferably a fluorinated polyimide-based resin represented by the above formulas (4) to (11) or the above formula (23) having a halogen group A base material composed of polyamide resin. Among them, from the viewpoint that the hardness can be further increased, it is more preferable to use a base material composed of a polyimide-based resin represented by the above formula (4).

Examples of polyester resins include at least one of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Ingredients of resin, 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 by the Beck method, for example. When using the Baker method to measure the refractive index of the resin base material 11, 10 pieces of the resin base material 11 are cut out. For the 10 pieces cut out, the refractive index standard solution is used to measure the refractive index respectively by the Baker method , The average value of the measured refractive indexes of the 10 fragments is taken as the refractive index of the resin substrate 11. The refractive index of the resin base material 11 may be 1.500 or more and 1.800 or less. In addition, the refractive index of the resin substrate 11 can also be measured with a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation) at a wavelength of 380~780nm, and the obtained average reflectance can be determined by the following The formula (1) is obtained. In order to prevent back reflection, the average reflectance (R) of the resin substrate 11 is set to a black polyvinyl chloride insulating tape (such as the product name "Yamato vinyl tape NO200-38-21", Yamato Corporation, 38mm width) is attached to the back of the resin base material 11 and measured.

R ₁ =(1-n ₁ ) ² /(1+n ₁ ) ² …(1)

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

The thickness of the resin substrate 11 is preferably 10 μm or more and 100 μm or less. If the thickness of the resin substrate is 10μm or more, curling of the optical film can be suppressed, and sufficient hardness can be obtained. Furthermore, even when the optical film is manufactured by roll to roll, wrinkles are less likely to occur , There is no risk of causing deterioration of the appearance. On the other hand, if the thickness of the resin substrate is 100 μm or less, the folding performance of the optical film is good, which can meet the requirements of the continuous folding test, and it is better in terms of the light weight of the optical film. The thickness of the resin substrate 11 is taken by using a scanning electron microscope (SEM) to photograph a cross section of the resin substrate 11, and the film thickness of the resin substrate 11 at 10 locations is measured in the image of the cross section, and the film at the 10 locations 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.

<<Functional layer>>

The functional layer 12 is a layer that functions as a hard coat layer. The functional layer 12 may have functions other than the hard coat property in addition to the hard coat property. In addition to hard coating properties, the functional layer 12 also has antistatic properties. That is, the functional layer 12 becomes an antistatic hard coat layer. The "hard coat" in this specification refers to a layer with a Martens hardness of 375 MPa or more in the center of the cross section of the hard coat. In this specification, the so-called "Martens hardness" refers to the hardness when the indenter is pressed into 500nm by hardness measurement by the nanoindentation method. The measurement of Martens hardness by the above-mentioned nanoindentation method is performed on the measurement sample using "TI950 TriboIndenter" manufactured by HYSITRON. Specifically, first, a block is made by embedding an optical film cut out of 1mm×10mm with an embedding resin, and a uniform thickness without holes, etc. is cut out from the block by a general slicing method Slices above 70nm and below 100nm. The production of slices can use the "Ultratome Microtome EM UC7" (Leica Microsystems Co., Ltd.), etc. Then, the remaining block after cutting off the non-porous and other uniform slices is used as the measurement sample. Then, in the cross section of the measurement sample obtained by cutting off the above section, under the following measurement conditions, the Berkovich indenter (triangular pyramid) as the above indenter was pressed into the center of the cross section of the functional layer by 500 nm, After remaining fixed and relaxing the residual stress, unload, measure the maximum load after relaxation, use the maximum load P _max (μN) and the recessed area A (nm ² ) with a depth of 500 nm to calculate the horse by P _{max /A} 'S hardness. The Martens hardness is the arithmetic mean of the values obtained by measuring 10 locations.

(Measurement conditions)

‧Load speed: 10nm/sec

‧Holding time: 5 seconds

‧Load unloading speed: 10nm/sec

‧Measuring temperature: 25℃

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. If the Martens hardness of the functional layer 12 is 500 MPa or more, the hardness sufficient 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 in 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 by using a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation) to measure the average reflectance at a wavelength of 380 to 780 nm, and use the obtained average reflectance by the following formula (2) And find out. The average reflectance of the functional layer 12 is set to be obtained by coating the composition for the functional layer on a polyethylene terephthalate (PET) substrate with a thickness of 50 μm that has not been subjected to easy bonding treatment and then It hardens to form a functional layer with a thickness of 1~10μm. On the surface of the PET substrate opposite to the functional layer side (back side), attach a black polyvinyl chloride insulating tape with a larger width than the area of the measuring point (for example, The product name is "Yamato vinyl tape NO200-38-21", manufactured by Yamato Corporation, width 38mm) to prevent back reflection, and then the measurement is carried out.

R ₂ =(1-n ₂ ) ² /(1+n ₂ ) ² …(2)

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

The film thickness of the functional layer 12 is preferably 2 μm or more and 40 μm or less. If 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. The "film thickness of the functional layer" in this specification refers to the film thickness (total thickness) obtained by adding up the film thickness of each functional layer 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 taken by using a scanning transmission electron microscope (STEM) or a transmission electron microscope (TEM) to take a cross-section of the functional layer 12, and measure the thickness of the functional layer 12 at 20 locations in the image of the cross-section. The film thickness is taken as the arithmetic average of the film thicknesses of the 20 locations. The following describes the specific method of taking the cross-sectional photos. First, make a block of an optical film cut out to a size of 1mm×10mm and embed it with an embedding resin, and cut out a uniform thickness of 70nm or more and 100nm without holes, etc. from the block by a general slicing method. The following slices. The production of slices can use the "Ultratome Microtome EM UC7" (Leica Microsystems Co., Ltd.), etc. Then, the uniform slice without holes or the like is used as a measurement sample. Thereafter, a scanning transmission electron microscope (STEM) (product name "S-4800", manufactured by Hitachi High-Technology Co., Ltd.) was used to take a cross-sectional photograph of the measurement sample. When using the above-mentioned S-4800 to take cross-sectional photos, set the detector to "TE", set the acceleration voltage to "30kV", and set the emission current to "10μA" for cross-sectional observation. Regarding the magnification, while adjusting the focus and distinguishing or observing each layer by contrast and brightness, adjust appropriately at 5000 to 200,000 times. The more preferable magnification is 10,000 to 100,000 times, and the more preferable magnification is 10,000 to 50,000 times, and the best magnification is 25,000 to 50,000 times. Furthermore, when using the above-mentioned S-4800 to take cross-sectional photos, you can also set the aperture to "beam detection aperture 3", the objective lens aperture to "3", and the W.D. to "8mm". 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 clearly as possible when performing cross-sectional observation. If it is difficult to observe the interface due to insufficient contrast, if dyeing treatments such as osmium tetroxide, ruthenium tetroxide, or phosphotungstic acid are applied, the interface between the organic layers becomes easier to observe, so dyeing treatment can also be performed. In addition, there are situations where the contrast of the interface is more difficult to distinguish at high magnification. In this case, the observation is also performed at the same time under low magnification. For example, observe at two magnifications of 25,000 times and 50,000 times, or 50,000 times and 100,000 times, etc., and calculate the arithmetic average at the double rate. Furthermore, the average value is used as the value of the film thickness of the functional layer.

Since the functional layer 12 becomes an antistatic hard coating, it contains a binder resin and an antistatic agent present in the binder resin. Furthermore, when the functional layer 12 is a hard coat layer that does not have antistatic properties, the antistatic agent may not be included. In addition, the functional layer 12 may contain a binder resin, etc., but may also contain particles such as inorganic particles or organic particles, ultraviolet absorbers, adhesive enhancers, leveling agents, and thixotropy within a range that does not impair the effects of the present invention. Additives such as imparting agents, coupling agents, plasticizers, defoamers, fillers, colorants, and fillers.

<Binder Resin>

The binder resin contains a polymer (cured product) of a polymerizable compound (curable compound). The polymerizable compound has at least one polymerizable functional group in the molecule. As a polymerizable functional group, ethylenic unsaturated groups, such as a (meth)acryl group, a vinyl group, and an allyl group, are mentioned, for example. Furthermore, the so-called "(meth)acryloyl group" includes both the meaning of "acryloyl group" and "methacryloyl group".

The polymerizable compound is preferably a polyfunctional (meth)acrylate. As said polyfunctional (meth)acrylate, for example, trimethylolpropane tri(meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, Dipropylene glycol di(meth)acrylate, neopentaerythritol tri(meth)acrylate, neopentaerythritol tetra(meth)acrylate, dineopentaerythritol hexa(meth)acrylate, 1,6 -Hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate , Dineopentaerythritol penta (meth) acrylate, trineopentaerythritol octa (meth) acrylate, tetrane pentaerythritol deca (meth) acrylate, tris (meth) isocyanurate Acrylate, isocyanuric acid di(meth)acrylate, polyester tri(meth)acrylate, polyester di(meth)acrylate, bisphenol di(meth)acrylate, diglycerol tetra(meth)acrylate Meth) acrylate, adamantyl di(meth)acrylate, isobornyl di(meth)acrylate, dicyclopentane di(meth)acrylate, tricyclodecane di(meth)acrylate , Ditrimethylolpropane tetra(meth)acrylate, or those modified with PO, EO, caprolactone, etc.

Among them, in terms of satisfying the above-mentioned Martens hardness, it is preferably 3-6 functional ones, for example, neopentylerythritol triacrylate (PETA), dineopentaerythritol six Acrylate (DPHA), neopentyl erythritol tetraacrylate (PETTA), dineopentaerythritol pentaacrylate (DPPA), trimethylolpropane tri(meth)acrylate, trineopentaerythritol octa (meth)acrylate Base) acrylate, tetraneopentyl erythritol deca(meth)acrylate and the like. In addition, in this specification, the so-called "(meth)acrylate" means "acrylate" and "methacrylate".

In addition, in order to adjust the hardness or the viscosity of the composition, improve the adhesion, etc., a monofunctional (meth)acrylate monomer may be further included. Examples of the above-mentioned monofunctional (meth)acrylate monomers include hydroxyethyl acrylate (HEA), glycidyl methacrylate, methoxy polyethylene glycol (meth)acrylate, (meth) Isostearyl acrylate, 2-propenoxyethyl succinate, acrylomorpholine, N-acryloyloxyethyl hexahydrophthalimide, cyclohexyl acrylate, tetrahydrofuran acrylate , Isobornyl acrylate, phenoxyethyl acrylate, and adamantyl acrylate, etc.

Regarding the weight average molecular weight of the above-mentioned monomer, from the viewpoint of increasing the hardness of the functional layer, it is preferably less than 1,000, and more preferably 200 or more and 800 or less. In addition, 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 in 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 ion-conducting antistatic agents and electron-conducting antistatic agents. From the viewpoint of compatibility with the binder resin, ion-conducting antistatic agents are preferred.

Examples of the ion-conducting antistatic agent include cationic antistatic agents such as quaternary ammonium salts and pyridine salts, alkali metal salts such as sulfonic acid, phosphoric acid, and carboxylic acid (for example, lithium salt, sodium salt, potassium salt, etc.) Anionic antistatic agents such as anionic antistatic agents, amphoteric antistatic agents such as amino acid series and amino acid sulfate ester series, and nonionic antistatic agents such as amino alcohol series, glycerin series, and polyethylene glycol series. Among them, a quaternary ammonium salt or a lithium salt is preferred in terms of showing excellent compatibility with the binder resin.

Examples of the electron-conducting antistatic agent include conductive polymers such as polyacetylene-based and polythiophene-based conductive particles, and conductive particles such as metal particles and metal oxide particles. Among these, preferred are antistatic agents, metal particles, and metal oxide particles formed by combining a dopant with a conductive polymer such as polyacetylene and polythiophene. In addition, conductive particles may be contained in the above-mentioned conductive polymer.

As the antistatic agent composed of the above-mentioned conductive polymer, specifically, polyacetylene, polyaniline, polythiophene, polypyrrole, polyphenylene sulfide, poly(1,6-heptadiyne), poly Conductive polymers such as biphenylene (poly-p-phenylene), poly-p-phenylene sulfide, polyphenylacetylene, poly(2,5-thienyl), or derivatives of these, preferably polythiophene-based conductive polymers Organic polymers (for example, 3,4-ethylenedioxythiophene (PEDOT), etc.).

By using the antistatic agent composed of the above-mentioned conductive organic polymer, the humidity dependence is small, the antistatic property can be maintained for a long time, and it has high transparency and low haze, and then hard coating High performance, especially can significantly improve pencil hardness, abrasion resistance to steel wool, etc.

The metal constituting the metal particles is not particularly limited, and examples thereof include simple substances such as Au, Ag, Cu, Al, Fe, Ni, Pd, and Pt, or alloys of these metals. In addition, the metal oxide constituting the metal oxide particles is not particularly limited, and examples include tin oxide (SnO ₂ ), antimony oxide (Sb ₂ O ₅ ), antimony-doped tin oxide (ATO), and tin-doped oxide. Indium (ITO), aluminum-doped zinc oxide (AZO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), etc.

The content of the antistatic agent is not particularly limited, and it 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 composition for the functional layer. If it is 1 part by mass or more, the above-mentioned antistatic properties can be sufficiently obtained, and if it is 50 parts by mass or less, a highly transparent film with a small haze value and 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 spectral transmittance adjuster, and/or an antifouling agent.

<Ultraviolet Absorber>

The optical film can be particularly preferably used in mobile terminals such as foldable smartphones or tablet terminals. However, since such mobile terminals are mostly used outdoors, there are polarizing elements arranged on the display element side of the optical film. The problem of easy deterioration due to 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 an ultraviolet absorber, the deterioration caused by the polarizing element being exposed to ultraviolet rays can be better prevented. Furthermore, the aforementioned ultraviolet absorber (UVA) may not be contained in the functional layer 12 but may be contained in the resin base material 11.

系紫外線吸收劑、二苯甲酮系紫外線吸收劑、及苯并三唑系紫外線吸收劑等。 As the ultraviolet absorber, for example, three

It is an ultraviolet absorber, a benzophenone-based ultraviolet absorber, and a benzotriazole-based ultraviolet absorber, etc.

系紫外線吸收劑，例如可列舉：2-(2-羥基-4-[1-辛氧基羰基乙氧基]苯基)-4,6-雙(4-苯基苯基)-1,3,5-三

、2-[4-[(2-羥基-3-十二烷氧基丙基)氧基]-2-羥基苯基]-4,6-雙(2,4-二甲基苯基)-1,3,5-三

、2,4-雙[2-羥基-4-丁氧基苯基]-6-(2,4-二丁氧基苯基)-1,3,5-三

、2-[4-[(2-羥基-3-十三烷氧基丙基)氧基]-2-羥基苯基]-4,6-雙(2,4-二甲基苯基)-1,3,5-三

、及2-[4-[(2-羥基-3-(2'-乙基)己基)氧基]-2-羥基苯基]-4,6-雙(2,4-二甲基苯基)-1,3,5-三

等。作為市售之三

系紫外線吸收劑，例如可列舉：TINUVIN460、TINUVIN477(均為BASF公司製造)、LA-46(ADEKA公司製造)等。 As the above three

UV absorbers, such as 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-tri

, 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 the third commercially available

The ultraviolet absorber includes, for example, TINUVIN460, TINUVIN477 (all manufactured by BASF Corporation), LA-46 (manufactured by ADEKA Corporation), and the like.

Examples of the aforementioned benzophenone-based ultraviolet absorbers include 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 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, etc. Examples of commercially available benzophenone-based ultraviolet absorbers include CHMASSORB81/FL (manufactured by BASF Corporation).

As the aforementioned benzotriazole-based ultraviolet absorber, for example, 2-ethylhexyl-3-[3-tertiarybutyl-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-(tertiary butyl)phenol, 2-(2H-benzotriazol-2-yl)-4,6-di Tertiary amylphenol, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3,5'-di-tert-butylphenyl)benzo Triazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3,5'-di-tert-butyl Phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthaliminomethyl)-5 '-Methylphenyl)benzotriazole, 2,2-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2 -Yl)phenol), and 2-(2'-hydroxy-3'-tertiarybutyl-5'-methylphenyl)-5-chlorobenzotriazole, etc. As commercially available benzotriazole ultraviolet absorbers, for example, KEMISORB71D, KEMISORB79 (all manufactured by Chemipro Kasei), JF-80, JAST-500 (all manufactured by Johoku Chemical Co., Ltd.), ULS-1933D (all manufactured by Johoku Chemical Co., Ltd.), ULS-1933D Manufactured by the company), RUVA-93 (manufactured by Otsuka Chemical Co.), etc.

系紫外線吸收劑、苯并三唑系紫外線吸收劑。紫外線吸收劑較佳為與構成功能層之樹脂成分之溶解性較高，又，較佳為上述連續摺疊試驗後之滲出較少者。紫外線吸收劑較佳為經聚合物化或低聚物化。作為紫外線吸收劑，較佳為具有苯并三唑、三

、二苯甲酮骨架之聚合物或低聚物，具體而言，較佳為使具有苯并三唑或二苯甲酮骨架之(甲基)丙烯酸酯與甲基丙烯酸甲酯(MMA)以任意之比率進行熱共聚而成者。再者，於將光學膜應用於有機發光二極體(OLED)顯示裝置之情形時，紫外線吸收劑亦可發揮保護OLED免受紫外線之影響之作用。 UV absorbers can be used particularly preferably

It is a UV absorber and a benzotriazole UV absorber. The ultraviolet absorber preferably has higher solubility with the resin component constituting the functional layer, and more preferably has less exudation after the above-mentioned continuous folding test. The ultraviolet absorber is preferably polymerized or oligomerized. As the ultraviolet absorber, it is preferable to have benzotriazole, triazole

, Polymers or oligomers of benzophenone skeleton, specifically, it is preferable to use (meth)acrylate with benzotriazole or benzophenone skeleton and methyl methacrylate (MMA) It is formed by thermal copolymerization at any ratio. Furthermore, when the optical film is applied to an organic light emitting diode (OLED) display device, the ultraviolet absorber can also play a role in protecting the OLED from ultraviolet rays.

The content of the ultraviolet absorber is not particularly limited, but it 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 composition for the functional layer. If it is 1 part by mass or more, the effect of containing the above-mentioned ultraviolet absorber in the functional layer can be sufficiently obtained, and if it is 6 parts by mass or less, there will be no significant coloration or strength reduction 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 is one that adjusts the spectral transmittance of the optical film. When the functional layer 12 contains, for example, a sesamol type benzotriazole-based monomer represented by the following general formula (25), the above-mentioned 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 alkylene group with 1 to 6 carbons or a linear or branched oxyalkylene group with 1 to 6 carbons.

The above-mentioned sesamol-type benzotriazole-based monomer is not particularly limited, and specific substance names include: methacrylic acid 2-[2-(6-hydroxybenzo[1,3]dioxane Penten-5-yl)-2H-benzotriazol-5-yl] ethyl ester, 2-[2-(6-hydroxybenzo[1,3]dioxol-5-yl) acrylic acid -2H-benzotriazol-5-yl] ethyl ester, methacrylic acid 3-[2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzo Triazol-5-yl]propyl ester, acrylic acid 3-[2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl] Propyl ester, methacrylic acid 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 ester, methacrylic acid 2-[2-( 6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yloxy]ethyl ester, acrylic acid 2-[2-(6-hydroxybenzo [1,3]Dioxol-5-yl)-2H-benzotriazol-5-yloxy]ethyl ester, methacrylic acid 2-[3-{2-(6-hydroxybenzo [1,3]Dioxol-5-yl)-2H-benzotriazol-5-yl}propanoxy]ethyl ester, 2-[3-{2-(6-hydroxybenzene) acrylic acid And [1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propionoxy]ethyl ester, methacrylic acid 4-[3-{2-(6 -Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propionoxy]butyl ester, acrylic acid 4-[3-{2-( 6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propionoxy]butyl ester, 2-[3-{methacrylic acid 2-(6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propionyloxy]ethyl ester, acrylic acid 2-[3- {2-(6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propionyloxy]ethyl ester, 2-(6- Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazole-5carboxylic acid 2-(methacryloyloxy) ethyl ester, 2-(acryloyloxy) ) Ethyl 2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazole-5-carboxylate, 4-(methacryloxy ) Butyl 2-(6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazole-5-carboxylate, 4-(acryloyloxy)butyl 2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazole-5-carboxylate and the like. In addition, these sesamol-type benzotriazole-based monomers may be used singly, or two or more kinds may be used.

<Antifouling agent>

The antifouling agent is not particularly limited, and examples thereof include silicone-based antifouling agents, fluorine-based antifouling agents, silicone-based and fluorine-based antifouling agents, and they may be used alone or in combination. In addition, as an antifouling agent, an acrylic antifouling agent may also be used.

The content of the antifouling agent is preferably 0.01 to 3.0 parts by mass relative to 100 parts by mass of the aforementioned polymerizable compound. If it is 0.01 parts 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, there is no possibility that the hardness of the functional layer will decrease.

The antifouling agent preferably has a weight average molecular weight of 5000 or less. In order to improve the durability of the antifouling performance, it is a compound having preferably one or more, more preferably two or more reactive functional groups. Among them, by using an antifouling agent having two or more reactive functional groups, excellent scratch resistance can be imparted.

When the antifouling agent does not have reactive functional groups, no matter when the optical film is in roll or sheet form, the antifouling agent will be transferred to the back of the optical film when overlapped, if If you want to attach or coat other layers on the back of the optical film, peeling of other layers may occur, and furthermore, it may be easy to peel off due to multiple consecutive folding tests.

Furthermore, the performance continuity (durability) of the antifouling performance of the antifouling agent with the above-mentioned reactive functional group becomes better, and the functional layer containing the above-mentioned fluorine-based antifouling agent is less likely to adhere (not easily noticeable) fingerprints, and wipe off Also good. Furthermore, since the surface tension at the time of application of the composition for the functional layer can be reduced, the leveling property is good, and the appearance of the formed functional layer becomes good.

The functional layer containing silicone antifouling agent has good sliding properties and good steel wool resistance. A touch sensor equipped with a functional layer containing an optical film containing such a polysiloxane-based antifouling agent has a good sliding touch when touched with a finger or a pen, and thus has a good tactility. In addition, fingerprints are not easily attached (not easily visible) to the functional layer, and the wiping properties are also improved. Furthermore, since the surface tension at the time of application of the composition for the functional layer can be reduced, the leveling property is good, and the appearance of the formed functional layer becomes good.

As a commercially available product of the polysiloxane-based antifouling agent, for example, SUA1900L10 (manufactured by Shinnakamura Chemical Co., Ltd.), SUA1900L6 (manufactured by Shinnakamura Chemical Co., Ltd.), Ebecryl1360 (manufactured by Daicel-Cytec Co., Ltd.), and UT3971 (manufactured by Nippon Gosei Co., Ltd.) ), BYKUV3500 (manufactured by BYK-Chemie), BYKUV3510 (manufactured by BYK-Chemie), BYKUV3570 (manufactured by BYK-Chemie), X22-164E, X22-174BX, X22-2426, KBM503, KBM5103 (manufactured by Shin-Etsu Chemical) , TEGO-RAD2250, TEGO-RAD2300, TEGO-RAD2200N, TEGO-RAD2010, TEGO-RAD2500, TEGO-RAD2600, TEGO-RAD2700 (manufactured by Evonik Japan), Megafac RS854 (manufactured by DIC), etc.

Examples of commercially available fluorine-based antifouling agents include: Optool DAC, Optool DSX (manufactured by Daikin Industrial Co., Ltd.), Megafac RS71, Megafac RS74 (manufactured by DIC Corporation), LINC152EPA, LINC151EPA, and LINC182UA (Kyoeisha Chemical Co., Ltd.) Manufacturing), Ftergent 650A, Ftergent 601AD, Ftergent 602, etc.

Commercial products of fluorine-based and silicone-based antifouling agents with reactive functional groups include, for example, Megafac RS851, Megafac RS852, Megafac RS853, Megafac RS854 (manufactured by DIC Corporation), Optar TU2225, Optar TU2224 ( JSR Corporation), X71-1203M (Shin-Etsu Chemical Corporation), etc.

<<The first optical adjustment layer>>

The optical adjustment layer 13 is a layer for suppressing the generation of interference fringes. The refractive index of the optical adjustment layer 13 is preferably lower than the refractive index of the resin base material 11 and higher than the refractive index of the functional layer 12 from the viewpoint of suppressing the occurrence 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-mentioned functional layer, so the description is omitted here.

The refractive index difference 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. If the refractive index difference is 0.005 or more, it can be a level where interference fringes cannot be seen although reflection at the interface between the optical adjustment layer 13 and the functional layer 12 occurs, and if it is 0.100 or less, it can be that a little interference can be confirmed. Streaks, but no problem level 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 also 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. If 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 foldability can be improved. The film thickness of the optical adjustment layer 13 can be obtained by the same method as that of 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 also be composed only of 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 (meth)acrylic resins, cellulose resins, urethane resins, vinyl chloride resins, polyester resins, polyolefin resins, and polyolefin resins. At least one resin 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 adhesiveness and the difference in refractive index, a combination of a polyester resin and metal oxide particles such as titanium oxide or zirconium oxide is more preferred.

In addition, in order to obtain antistatic properties, the optical adjustment layer 13 may 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 making the optical adjustment layer 13 contain an antistatic agent, 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. As the antistatic agent contained in the optical adjustment layer 13, the same antistatic agent described in the column of the functional layer 12 can be used, so the description is omitted here.

<<Second optical adjustment layer>>

The optical adjustment layer 14 is mainly used to improve the adhesion between the resin base material 11 and the optical adjustment layer 13 without generating interference fringes. Since the optical adjustment layer 14 is provided between the resin base material 11 and the optical adjustment layer 13, the adhesion can be improved compared to when the resin base material 11 and the optical adjustment layer 13 are in direct contact.

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

The refractive index difference 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. If the refractive index difference is 0.005 or more, it can be a level where interference fringes cannot be seen although reflection at the interface between the optical adjustment layer 14 and the optical adjustment layer 13 occurs, and if it is less than 0.100, it can be slightly confirmed. The level of 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 also 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. If 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 base material 11 and the optical adjustment layer 14 can be ensured, and if it is 200 nm or less, it is not 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 foldability can be improved. The film thickness of the optical adjustment layer 14 is determined by the same method as that of 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 also be composed only of 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 (meth)acrylic resins, cellulose resins, urethane resins, vinyl chloride resins, polyester resins, polyolefin resins, polycarbonate, nylon, At least one resin 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 silicon dioxide 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 adhesiveness and the difference in refractive index, a combination of a polyester resin and metal oxide particles such as titanium oxide or zirconium oxide is more preferred.

In addition, in order to obtain antistatic properties, the optical adjustment layer 14 may 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 making the optical adjustment layer 14 contain an antistatic agent, 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, if 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. As the antistatic agent contained in the optical adjustment layer 14, the same antistatic agent described in the column of the functional layer 12 can be used, so the description is omitted here.

<<3rd optical adjustment layer>>

The optical adjustment layer 15 is a layer that improves the light transmittance of the optical film 10. The refractive index of the optical adjustment layer 15 is higher than 1.000 which is the refractive index of air, and 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, so the description is omitted here.

The refractive index difference 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. If the refractive index difference is 0.005 or more, the light transmittance of the optical film 10 can be improved, and if it is 0.700 or less, the transparency of the optical film 10 will not be 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 also 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. If 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 that of the functional layer 12. The lower limit of the optical adjustment layer 15 is more preferably 50 nm or more, the upper limit is more preferably 700 nm or less, and more preferably 500 nm or less.

The structure of the optical adjustment layer 15 is not particularly limited as long as it has a refractive index higher than 1.000 and lower than the refractive index of the resin base material 11. The optical adjustment layer 15 may be composed of resin. In addition to containing 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 reduce the refractive index. In addition, in order to obtain antistatic properties, the optical adjustment layer 15 may 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. Furthermore, in order to adjust the color tone of the optical film 10, the optical adjustment layer 15 may contain the color tone adjustment agent, such as the said spectral transmittance adjustment agent.

<Resin>

The resin is preferably selected from (meth)acrylic resins, cellulose resins, urethane resins, vinyl chloride resins, polyester resins, polyolefin resins, polycarbonate, nylon, polystyrene, and At least one resin in the group consisting of ABS resin. Among them, from the viewpoint of adhesion to the resin substrate 11, (meth)acrylic resins, urethane resins, polyester resins, and the like are preferred.

As the above-mentioned (meth)acrylic resin, for example, polymethyl methacrylate and the like can be cited. Moreover, as said cellulose resin, diacetyl cellulose, cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), etc. are mentioned, for example. As said urethane resin, a urethane resin etc. are mentioned, for example.

As said vinyl chloride resin, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, etc. are mentioned, for example. Moreover, as said polyester resin, polyethylene terephthalate etc. are mentioned, for example. Moreover, as said polyolefin resin, polyethylene, polypropylene, etc. are mentioned, for example.

<Low refractive index particles>

Examples of the low refractive index particles include solid or hollow particles composed of silicon dioxide or magnesium fluoride. Among them, hollow silica particles are preferred, and such hollow silica particles can be produced, for example, by the manufacturing method described in the Examples of Japanese Patent Application Laid-Open No. 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. If the average particle size of the low refractive index particles is within the above range, the transparency of the optical adjustment layer 15 will not be impaired, and a good dispersion state of the particles can be obtained. The average particle size of the low-refractive-index particles is determined by the cross-sectional image of the optical adjustment layer 15 taken with a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM) to determine the particle size of 20 low-refractive-index particles , Using the arithmetic average of the particle diameters of 20 low refractive index particles. 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, and still more preferably 70 nm or less.

As the low refractive index particles, silica particles having reactive groups on the surface (reactive silica particles) are preferred, and reactive hollow silica particles are particularly preferred. Such silicon dioxide particles with reactive groups on the surface can be produced by surface treatment of silicon dioxide particles with a silane coupling agent or the like. As a method of treating the surface of silica particles with a silane coupling agent, there can be mentioned: a dry method of spraying silica particles with a silane coupling agent, or adding a silane coupling agent after the silica particles are dispersed in a solvent. The wet method of reaction, etc.

<Antistatic Agent>

As the antistatic agent contained in the optical adjustment layer 15, the same antistatic agent described in the column of the functional layer 12 can be used, so the description is omitted here.

<<The manufacturing method of optical film>>

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

<Composition for the second optical adjustment layer>

The composition for the second optical adjustment layer contains particles such as binder resin precursors, metal oxides, and solvents. In this specification, the "binder resin precursor" refers to the component that becomes the binder resin by removing the solvent or curing it with heat or ionizing radiation.

Examples of binder resin precursors include solvent-dried resins and polymerizable compounds that are cured by heat or ionizing radiation. Examples of ionizing radiation in this specification include visible rays, ultraviolet rays, X-rays, electron beams, α rays, β rays, and γ rays. The composition for the second optical adjustment layer may optionally contain at least any one of low refractive index particles such as silicon dioxide or magnesium fluoride, inorganic pigments such as cobalt blue, a leveling agent, and a polymerization initiator. In addition, when polyester resin is used as the binder resin precursor, the composition for the second optical adjustment layer may optionally contain (meth)acrylic resins, cellulose resins, and urethane resins. , Vinyl chloride resin, polyolefin resin, polycarbonate, nylon, polystyrene, and ABS resin.

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

Then, the first optical adjustment layer composition for forming the optical adjustment layer 13 is coated on the optical adjustment layer 14 by a coating device such as a bar coater to form the first optical adjustment layer composition涂膜。 Coating.

<Composition for the first optical adjustment layer>

The composition for the first optical adjustment layer contains particles such as binder resin precursors, metal oxides, and solvents. The composition for the first optical adjustment layer may optionally contain at least any one of low refractive index particles such as silicon dioxide or magnesium fluoride, inorganic pigments such as cobalt blue, a leveling agent, and a polymerization initiator. In addition, when polyester resin is used as the binder resin precursor, the first optical adjustment layer composition may optionally contain (meth)acrylic resins, cellulose resins, and urethane resins. , Vinyl chloride resin, polyolefin resin, polycarbonate, nylon, polystyrene, and ABS resin.

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

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

<Composition for functional layer>

The composition for the functional layer contains a polymerizable compound that becomes a binder resin after curing. The composition for the functional layer may also optionally contain an antistatic agent, an ultraviolet absorber, a spectral transmittance adjuster, an antifouling agent, an inorganic particle, a leveling agent, a solvent, and a polymerization initiator.

(Solvent)

烷、四氫呋喃)、醚醇(例如1-甲氧基-2-丙醇)、碳酸酯(碳酸二甲酯、碳酸二乙酯、碳酸甲酯乙酯)等。該等溶劑可單獨使用，亦可併用2種以上。其中，作為上述溶劑，就使(甲基)丙烯酸胺酯等成分、以及其他添加劑溶解或分散，可較佳地塗敷功能層用組成物之方面，較佳為甲基異丁基酮、甲基乙基酮。 Examples of the above-mentioned solvents include alcohols (for example, methanol, ethanol, propanol, isopropanol, n-butanol, second butanol, tertiary butanol, benzyl alcohol, PGME, ethylene glycol, diacetone alcohol), ketones (E.g. 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 (e.g. hexane, cyclohexane), halogenated hydrocarbons (e.g. dichloromethane, chloroform, four Carbon chloride), aromatic hydrocarbons (e.g. benzene, toluene, xylene), amides (e.g. dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ethers (e.g. diethyl ether, two

Alkanes, tetrahydrofuran), ether alcohols (e.g. 1-methoxy-2-propanol), carbonates (dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate) and the like. These solvents may be used alone or in combination of two or more kinds. Among them, as the above-mentioned solvent, in terms of dissolving or dispersing components such as (meth)acrylate amine ester and other additives, and can preferably coat the composition for the functional layer, methyl isobutyl ketone, methyl isobutyl ketone, and methyl isobutyl ketone are preferable in terms of dissolving or dispersing components such as (meth) acrylate and other additives.基ethyl ketone.

(Polymerization initiator)

The polymerization initiator is a component that decomposes under the irradiation of ionizing radiation to generate free radicals to start or proceed the polymerization (crosslinking) of the polymerizable compound.

類、苯丙酮類、苯偶醯類、安息香類、醯基氧化膦類。又，較佳為混合光敏劑而使用，作為其具體例，例如可列舉：正丁胺、三乙胺、聚正丁基膦等。 The polymerization initiator is not particularly limited as long as it can release a substance that initiates radical polymerization by irradiation with ionizing radiation. The polymerization initiator is not particularly limited, and known ones can be used. Specific examples include, for example, acetophenones, benzophenones, Michler benzoic acid benzoate, and α-pentyl oxime. Ester, 9-oxysulfur

Type, phenylacetone, benzil, benzoin, phosphine oxide. Moreover, it is preferable to mix and use a photosensitizer, and as a specific example, n-butylamine, triethylamine, poly-n-butyl phosphine, etc. are mentioned, for example.

After the coating film of the composition for the functional layer is formed, the coating film is dried by heating the coating film at a temperature of 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 harden the coating film. Thereby, the functional layer 12 adjacent to the optical adjustment layer 13 is formed.

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

<The third optical adjustment layer composition>

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 any one of low refractive index particles, antistatic agents, inorganic pigments such as cobalt blue, leveling agents, and polymerization initiators. In addition, when polyester resin is used as the resin precursor, the composition for the third optical adjustment layer may optionally contain (meth)acrylic resins, cellulose resins, urethane resins, and chlorine. One or more resins 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 of the composition for the functional layer, so the description is omitted here.

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

<<<Other optical films>>>

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

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 , And adjacent to the functional layer 12. Furthermore, 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 the physical properties and the like of the optical film 10, so the description is omitted here. The front surface 30A of the optical film 30 becomes the front surface 12A of the functional layer 12, and the back surface 30B of the optical film 30 becomes the surface 15A of the optical adjustment layer 15 on the opposite side to 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 Between, and adjacent to the functional layer 12; and the resin layer 41, which is provided on the second surface 11B of the resin substrate 11. Furthermore, 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 becomes the front surface 12A of the functional layer 12, and the back surface 30B of the optical film 40 becomes the surface 41A of the resin layer 41 on the opposite side to the resin substrate 11 side.

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 Between and adjacent to the functional layer 12; the resin layer 41, which is provided on the second surface 11B side of the resin substrate 11; and the optical adjustment layer 15, which is provided between the resin substrate 11 and the resin layer 41, and is adjacent to Resin substrate 11. Furthermore, 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 becomes the front surface 12A of the functional layer 12, and the back surface 50B of the optical film 50 becomes the surface 41A of the resin layer 41 on the opposite side to 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 Between and adjacent to the functional layer 12; the optical adjustment layer 14, which is disposed between the resin substrate 11 and the optical adjustment layer 13, and is adjacent to the resin substrate 11; the resin layer 41, which is disposed on the first part of the resin substrate 11 2 side 11B side; and the optical adjustment layer 15, which is provided between the resin base material 11 and the resin layer 41, and is adjacent to the resin base material 11. Furthermore, the front surface 60A of the optical film 60 becomes the front surface 12A of the functional layer 12, and the back surface 60B of the optical film 60 becomes the surface 41A of the resin layer 41 on the opposite side to the resin substrate 11 side.

In the optical films 40, 50, and 60, the shear storage modulus G'in the frequency region above 500 Hz and below 1000 Hz at 25° C. exceeds 200 MPa and is below 1200 MPa. If the shear storage modulus G'of the film exceeds 200MPa, when an impact is applied to the front surface of the optical film, not only the deformation of the optical film itself can be suppressed, but also even when the optical film is more closely located inside the image display device In the case of the adhesive layer, plastic deformation of the adhesive layer can also be suppressed. In addition, if the shear storage modulus G'of the optical films 40, 50, 60 is 1200 MPa or less, the optical film 40 can be prevented from breaking when folded. The lower limit of the shear storage modulus G'of the optical films 40, 50, 60 is preferably 400 MPa or more, and more preferably 500 MPa or more. By setting 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 this upper limit, good recoverability can be obtained when the folded is allowed to stand still and then opened again.

In the optical films 40, 50, 60, the shear loss modulus G" in the frequency region above 500 Hz and below 1000 Hz at 25° C. becomes 3 MPa or more and 150 MPa or less. If the shear loss modulus G" of the optical film is 3MPa or more, the reduction of impact absorption performance can be suppressed. In addition, if the shear loss modulus G" of the optical films 40, 50, 60 is 150 MPa or less, the decrease in the hardness of the resin layer 41 can be suppressed. The lower limit of the shear loss modulus G" of the optical film 40 is preferably 20 MPa As mentioned above, 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 thinning of the optical films 40, 50, and 60.

Shear storage modulus G'and shear loss modulus G" can be measured by a dynamic viscoelasticity measuring device (DMA). When measuring the shear storage modulus of the optical film 40 by a dynamic viscoelasticity measuring device (DMA) In the case of G'and shear loss modulus G", first, the optical film 40 is punched into a rectangular shape of 10 mm×5 mm to obtain a sample. Next, two pieces of this sample were prepared, and they were attached to a solid shear jig as 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 metal solid shearing plate (middle plate) with a thickness of 1 mm and two L-shaped metals arranged on both sides of the solid shearing plate 71 Piece 72 (outer plate), a sample is sandwiched between the solid shear plate 71 and an L-shaped metal piece 72, and another sample is sandwiched between the solid shear plate 71 and another L-shaped metal piece 72 . In this case, the sample S is sandwiched so that the resin layer becomes the solid shear plate 51 side and the functional layer becomes the L-shaped metal fitting 72 side. Then, the L-shaped metal fittings 72 are fastened with screws 53 to fix the sample S. Then, after installing a tensile test chuck composed of an upper chuck and a lower chuck on the dynamic viscoelasticity measuring device (product name "Rheogel-E4000", manufactured by UBM Co., Ltd.), the upper chuck and the lower chuck Between the chucks, a solid cutting fixture is installed at a distance of 20mm between the chucks. The distance between the chucks is the distance between the upper chuck and the lower chuck. Then, the set temperature was set to 25°C and the temperature was increased at 2°C/min. In this state, a solid shear plate 71 is fixed on one side and a longitudinal vibration with a strain of 1% and a frequency of 500 Hz or more and 1000 Hz or less is applied to the two L-shaped metal parts 72, and the dynamic adhesion of the solid at 25 ℃ is performed. Elasticity measurement, measuring the shear storage modulus G'and shear loss modulus G" of the optical film 40, 50, 60. Here, the shear storage modulus G of the optical film in the frequency region above 500 Hz and below 1000 Hz 'And shear loss modulus G" is set to the value obtained by applying longitudinal vibration of 500Hz, 750Hz, 950Hz to the L-shaped metal parts, and measuring the shear storage of the optical film at each frequency Modulus G'and shear loss modulus G", calculate the arithmetic average of these shear storage modulus G'and shear loss modulus G", and then repeat the measurement 3 times to obtain 3 An arithmetic average is further performed arithmetic average. Furthermore, in the above, the reason for setting the frequency region above 500 Hz and below 1000 Hz is that the frequency of this frequency region is a frequency that deforms the front surface of the optical film from a few micrometers to tens of micrometers when an object falls freely from a height of several cm. , And it is the frequency of causing damage to the display panel, etc., which are more inside the image display device than the optical film.

The physical properties of the optical films 40, 50, and 60 are the same as the physical properties of the optical film 10 except for the above, so the description is omitted here.

<<Resin layer>>

The resin layer 41 is a layer composed of a resin having translucency. 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. If the film thickness of the resin layer 41 is 50 μm or more, the hardness of the resin layer 41 can be suppressed from decreasing, and if it is 300 μm or less, the thickness can be reduced without deterioration in processability. The film thickness of the resin layer 41 is taken by using a scanning electron microscope (SEM) to photograph the cross section of the resin layer 41, and the film thickness of the resin layer 41 at 20 locations is measured in the image of the cross section, and the arithmetic of the film thickness of the 20 locations is used 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 more preferably 100 μm or less.

As long as the resin constituting the resin layer 41 is a resin whose shear storage modulus G'and shear loss modulus G" in the frequency region above 500 Hz and below 1000 Hz at 25° C. of the optical film 40 fall within the above range, then It is not particularly limited. Examples of such resins include acrylic gels, urethane gels, silicone gels, urethane resins, epoxy resins, etc. Among them, preferred are Acrylic gel. The so-called "gel" generally refers to a dispersion system that loses fluidity at high viscosity. In addition, the resin layer 41 may contain rubber or thermoplastic elastomer in addition to acrylic gel or urethane resin.

(Acrylic gel)

As the acrylic gel, various types can be used as long as it is a polymer obtained by polymerizing monomers containing acrylates for adhesives and the like. Specifically, as the acrylic gel, for example, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, ( Isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-hexyl (meth)acrylate, n-pentyl (meth)acrylate, isoamyl (meth)acrylate, (meth) Octyl acrylate, isooctyl (meth)acrylate, isomyristyl (meth)acrylate, lauryl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, (meth)acrylate Acrylic monomers such as isodecyl acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate are polymerized or copolymerized. In this specification, the term "(meth)acrylate" includes both the meaning of "acrylate" and "methacrylate". In addition, the acrylate used in the above (co)polymerization may be used alone, or two or more of them may be used in combination.

(Amino ester resin)

The urethane resin is a resin having urethane bonds. Examples of the urethane resin include a cured product of an ionizing radiation-curable urethane resin composition or a cured product of a thermosetting urethane resin composition. Among these, from the viewpoint of obtaining high hardness, fast curing speed, and excellent mass productivity, a cured product of an ionizing radiation curable urethane resin composition is preferred.

The ionizing radiation curable urethane resin composition contains (meth)acrylate urethane, and the thermosetting urethane resin contains a polyol compound and an isocyanate compound. The amine (meth)acrylate, polyol compound, and isocyanate compound may be any of monomers, oligomers, and prepolymers.

The number of (meth)acrylic groups (the number of functional groups) in the amine (meth)acrylate is preferably 2 or more and 4 or less. If the number of (meth)acrylic groups in the (meth)acrylate amine ester is less than 2, the pencil hardness may decrease, and if it exceeds 4, the curing shrinkage may increase, and the optical film may curl. In addition, cracks may occur in the resin layer at the time of bending. The upper limit of the number of (meth)acrylic acid groups in the (meth)acrylate amine ester is more preferably 3 or less. Furthermore, the so-called "(meth)acryloyl" includes both the meaning of "acryloyl" and "methacryloyl".

The weight average molecular weight of the (meth) amine acrylate is preferably 1,500 or more and 20,000 or less. If the weight average molecular weight of the urethane (meth)acrylate is less than 1500, the impact resistance may decrease, and if it exceeds 20,000, the viscosity of the ionizing radiation curable urethane resin composition may increase and the coating properties may be increased. The danger of deterioration. The lower limit of the weight average molecular weight of (meth)acrylate amine is more preferably 2000 or more, and the upper limit is more preferably 15000 or less.

Moreover, as a repeating unit which has a structure derived from (meth)acrylate amine ester, the structure etc. which are represented by the following general formula (26), (27), (28), or (29) are mentioned, for example.

In the above general 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 to 3.

In the above general 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 ethyl, n represents an integer of 1 or more, and x represents an integer of 0-3.

In the above general 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 to 3.

In the above general formula (29), 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, n represents an integer of 1 or more, and x represents an integer of 0-3.

Furthermore, the structure of the polymer chain (repeating unit) of the resin constituting the resin layer 41 can be judged by analyzing the resin layer 41 by thermal decomposition GC-MS and FT-IR, for example. In particular, 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 above 500 Hz and below 1000 Hz are within the above ranges, It may contain ultraviolet absorbers, spectral transmittance modifiers, antifouling agents, inorganic particles and/or organic particles, etc. The ultraviolet absorbers may be the same as those described in the column of the functional layer 12. Therefore, The description is omitted here.

<<<Image display device>>>

The optical films 10, 30, 40, 50, 60 can be incorporated into a foldable image display device for use. Fig. 9 is a schematic configuration diagram of the image display device of this embodiment. As shown in FIG. 9, the image display device 80 is mainly laminated with a housing 81 for accommodating batteries and the like, a protective film 82, a display element 83, a circular polarizer 84, a touch sensor 85, and an optical film in order toward the observer side. 10. A light-transmitting adhesive layer 86 is arranged 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 components 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 polarizer 84, between the circular polarizer 84 and the touch sensor 85, between the touch sensor 85 and the optical film 10, but the adhesive layer The arrangement part is not particularly limited as long as it is between the optical film and the display element.

The optical film 10 is arranged so that the functional layer 12 is closer to the observer side than the resin base material 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 image display device 80, the display element 83 becomes an organic light emitting diode element including an organic light emitting diode or the like. The touch sensor 85 is arranged closer to the observer side than the circular polarizing plate 84, but it may also be arranged between the display element 83 and the circular polarizing plate 84. In addition, the touch sensor 85 may also be in a table-in or in-line mode. As the adhesive layer 86, for example, OCA (Optical Clear Adhesive) can be used.

According to this embodiment, one or more resins selected from the group consisting of polyimide resins, polyimide resins, polyamide resins, and polyester resins are used. The resin base material 11 is provided with an optical adjustment layer 13 adjacent to the functional layer 12 between the resin base material 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 becomes 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 increases, which may reduce the light transmittance. In particular, when using a resin base composed of one or more resins selected from the group consisting of polyimide resins, polyimide resins, polyamide resins, and polyester resins 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. In contrast, in this embodiment, since the second surface 11B of the resin substrate 11 is provided with an optical adjustment layer 15 having a refractive index higher than 1.000 and lower than the refractive index of the resin substrate 11, it is combined with the resin substrate 11 Compared with when the air layer is in contact, the interface reflection can be reduced, and the light reflectivity can be reduced. Thereby, the light transmittance of the optical films 10 and 30 can be improved.

In addition, when the optical adjustment layer 15 contains an antistatic agent, since the optical films 10, 30, 50, 60 have a functional layer 12 as an antistatic hard coat layer on the first surface 11A side of the resin substrate 11, the resin The second surface 11B side of the base material 11 is provided with the optical adjustment layer 15 containing an antistatic agent, so it is possible to prevent dust and the like from adhering to the optical films 10, 30, 50, 60. In this case, in a state where protective films (not shown) are attached to both sides of the optical films 10, 30, 50, and 60, even if the protective films are peeled off from the optical films 10, 30, 50, and 60, It can also suppress the electrification of the optical films 10, 30, 50, and 60. Thereby, the yield rate of the assembling steps of the image display device can be improved.

For optical films used in foldable image display devices, impact resistance is sometimes required due to the impact on the front of the optical film. Here, when an impact is applied to the front surface of the optical film, the front surface of the optical film may be sunken. In addition, there are display panels (such as organic light-emitting diode panels) that exist inside the optical film in the image display device. Such as component damage. Regarding the depressions on the front side of the optical film, there are depressions generated by the optical film itself and depressions generated by a soft layer such as an adhesive layer disposed inside the image display device closer to the optical film. The so-called "sags generated by the optical film itself" refers to the sags generated by the deformation of the optical film itself due to the impact when an impact is applied to the front of the optical film. The so-called "sags generated by the soft layer" It means that because the layer is soft, when an impact is applied to the front surface of the optical film, the soft layer disposed in the image display device than the optical film undergoes plastic deformation, and the optical film follows the plastic deformation of the soft layer, resulting in depressions . Therefore, at present, in optical films, it is preferable to suppress the depressions generated by the optical film itself and the depressions generated by the soft layer when an impact is applied to the front surface of the optical film, and it is possible to obtain more Rely on the excellent impact resistance that the internal components of the image display device are not damaged. Here, as an index showing the impact absorption performance, the shear loss tangent tanδ is previously known. Therefore, it is also considered that the shear loss tangent tanδ is used to express the impact resistance of an optical film having a structure with a functional layer on the first surface side of the resin substrate and a resin layer on the second surface side. However, regarding the shear loss tangent tanδ, When an impact is applied to the front surface of the optical film (the surface of the functional layer), the depression of the optical film surface generated by the optical film itself and the depression of the front surface of the optical film generated by the soft layer cannot be suppressed, and it is located more than the optical film. Rely on damage to the internal components of the image display device. It is believed that the reason is that the shear loss tangent tanδ is the ratio of the shear loss modulus G" to the shear storage modulus G'(G"/G'). The inventors of the present invention have continued their intensive research and found that in order to suppress the surface depression caused by the optical film itself and the surface depression generated by the soft layer when an impact is applied to the front surface of the optical film, it is more reliable than the optical film. The damage to the internal components of the image display device is important to the balance of the film thickness of the resin layer, the shear storage modulus G', and the shear loss modulus G". According to this embodiment, the resin substrate 11 is the first In the optical films 40, 50, and 60 having a structure with a functional layer 12 on the side 11A and a resin layer 41 on the second side 11B, the thickness of the resin layer 41 is reduced to 50 μm or more and 300 μm or less. The shear storage modulus G'exceeds 200 MPa and is 1200 MPa or less, and the above-mentioned shear loss modulus G" of the optical film 40 becomes 3 MPa or more and 150 MPa or less, so it can be folded, and an impact is applied to the front surface 40A of the optical film 40 Under the circumstances, it can suppress the depression of the front surface 40A, 50A, 60A produced by the optical film 40, 50, 60 itself and the optical film produced by the soft layer that exists in the image display device more than the optical film 40, 50, 60. 40, 50, 60 are recessed on the front side 40A, 50A, 60A, and can prevent damage to the display element 83 and other components located inside the image display device. Thereby, excellent impact resistance can be obtained.

[Second Embodiment]

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

<<<Optical Film>>>

The optical film 90 shown in FIG. 10 is used for image display devices and can be folded.

The optical film 90 includes: a light-transmitting substrate 91; a first antistatic layer 92 (hereinafter also referred to as the antistatic layer 92), which is provided on one side of the light-transmitting substrate 91, that is, the first surface 91A side; and The second antistatic layer 93 (hereinafter sometimes referred to simply as the antistatic layer 93) is provided on the second surface 91B side, which is the surface opposite to the first surface 91A of the translucent base 91. Furthermore, at least any one of between the translucent base 91 and the antistatic layer 92 and between the translucent base 91 and the antistatic layer 93 may have a functional layer.

A protective film may be attached to the surface of the antistatic layers 92, 93 on the opposite side to the surface on the translucent base 91 side. However, since the protective film is peeled off during use, the protective film is not regarded as a part of the optical film. Furthermore, the physical property values of the optical film 90 in this specification are the values in the state where no protective film is 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 becomes a surface 93A of the antistatic layer 93 on the opposite side to the surface on the translucent base 91 side.

The optical film 90 is foldable. Specifically, it is preferable that the optical film 90 is not cracked or broken even when the optical film 90 is repeatedly subjected to the folding test (continuous folding test) described below for 100,000 times. , It is more preferable that the optical film 90 does not crack or break even when the continuous folding test is repeated 200,000 times, and it is more preferable that the optical film 90 is not broken even when the optical film 90 is repeated 1 million times. Cracks or breaks occur. When the optical film 90 is repeatedly subjected to a continuous folding test 100,000 times, if cracks or the like occur in the optical film 90, the foldability of the optical film 90 becomes insufficient. The continuous folding test can be carried out as if the optical film 90 is folded with the antistatic layer 92 on the inside, or can be carried out as if the optical film 90 is folded with the antistatic layer 92 on the outside, preferably in either case. None of the optical films were cracked or broken. The continuous folding test was performed by the same method as in the first embodiment, but in the continuous folding test of this embodiment, it was performed in a state where the distance between the sides was set to 3 mm.

By the same method as in the first embodiment, the optical film 90 was allowed to stand at 70°C for 240 hours after a folding and standing test, the folded state was released, and the opening degree of the optical film 90 was measured 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 can be carried out as if the optical film 90 is folded with the antistatic layer 92 on the inside, or can be carried out as if the optical film 90 is folded with the antistatic layer 92 on the outside, preferably in either case When the opening angle θ is 100° or more.

The surface resistance value 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 was measured by the same method as the method described in the first embodiment.

Regarding the front surface 90A of the optical film 90 (the front surface 92A of the antistatic layer 92), the hardness (pencil hardness) when measured by the pencil hardness test specified in JIS K5600-5-4: 1999 is preferably F or more, more preferably Above 2H. The pencil hardness test was measured 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 preferably applied at a distance of 50 mm from the front surface 90A of the optical film 90 under an environment of 23° C. and a relative humidity of 50%. At a voltage of 10kV, the saturation band voltage of 90A on the front side of the optical film 90 exceeds 0kV. The saturation band voltage was measured by the same method as that described in the first embodiment. The lower limit of the absolute value of the saturation band voltage is more preferably 0.1 kV or more, and the upper limit of the absolute value of the saturation band voltage is more preferably 1.0 kV or less.

Regarding the optical film 90, it is preferable that the yellow index (YI) is 15 or less for the same reasons as those described in the first embodiment. The yellow index is the one measured by the same method as that described in the first embodiment. The upper limit of the yellow index (YI) of the optical film 90 is more preferably less than 10, and most preferably less than 1.5.

From the side of the antistatic layer 93 toward the optical film 90, irradiate light with a continuous spectrum in the wavelength range from 300nm to 780nm at an incident angle of 0°, and obtain the L ^* a of the light (transmitting light) penetrating the optical film 90 ^* b ^* The 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 ranges, when the optical film is used in a mobile terminal, the yellow tone of the image becomes inconspicuous. a ^* and b ^* are those 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 above-mentioned haze value is assumed to be measured by the same method as that described in the first embodiment. The above-mentioned haze value is more preferably 1.5% or less, and more preferably 1.0% or less.

The optical reflectance (reflective Y value) of light with a wavelength of 380 nm to 780 nm of the optical film 90 is preferably 15% or less. If the above-mentioned visual reflectance of the optical film is 8% or less, when the optical film is used in a mobile terminal, the reflected light becomes less and it becomes easier to see. The above-mentioned visual reflectance is based on the use of a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation, light source: tungsten lamp and deuterium lamp), and light with a wavelength of 380nm~780nm is irradiated from the front side of the optical film. Measure the light reflected by the optical film with a wavelength of 380nm~780nm. Specifically, irradiate light with an incident angle of 5 degrees from the front side of an optical film cut into a size of 5cm×10cm, receive the reflected light in the regular reflection direction reflected by the optical film, and measure the reflectance in the wavelength range of 380nm~780nm. After that, the visual reflectance is calculated by software that converts the brightness perceived by the human eye (such as the software built in UV-2450). The above-mentioned visual reflectance is more preferably 10% or less, and still more preferably 3% or less.

The other physical properties, usage, and size of the optical film 90 are also the same as those of the optical film 10, so the description is omitted here.

<<Translucent substrate>>

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

The translucent substrate 91 is preferably a resin substrate. As the resin constituting the resin base material, the same resin as that of the resin base material 11 can be used, so the description is omitted here.

<<The first antistatic layer>>

The antistatic layer 92 is a layer that imparts antistatic properties to the front surface 90A of the optical film 90. In addition to antistatic properties, the antistatic layer 92 may also have functions other than 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 coating is a hard coating with antistatic properties.

Regarding the antistatic layer 92, it is preferable that the Martens hardness of the center of the cross section of the antistatic layer 92 is 500 MPa or more and 2000 MPa or less. If the Martens hardness of the antistatic layer 92 is 500 MPa or more, a hardness sufficient as an antistatic hard coating layer can be obtained, and if it is less than 2000 MPa, a good folding performance of the optical film can be obtained. The lower limit of the Martens hardness in 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 was 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. If the film thickness of the antistatic layer 92 is 1 μm or more, sufficient hardness as an antistatic hard coat layer can be obtained, and if it is 50 μm or less, deterioration of workability can be suppressed. In this specification, the "film thickness of the antistatic layer" refers to the film thickness (total thickness) obtained by adding up the film thickness of each antistatic layer when the antistatic layer has a multilayer structure. The film thickness of the antistatic layer 92 is set to be 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 existing in the binder resin. In addition to the antistatic layer 92 containing a binder resin, etc., it may also contain particles such as inorganic particles or organic particles, ultraviolet absorbers, adhesive enhancers, leveling agents, and thixotropy imparting agents within a range that does not impair the effects of the present invention. Additives such as additives, coupling agents, plasticizers, defoamers, fillers, colorants, and fillers.

<Binder Resin>

The adhesive resin is the same as the adhesive resin explained in the column of the functional layer 12, so the explanation is omitted here.

<Antistatic Agent>

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

The antistatic layer 92 may further contain an ultraviolet absorber, a spectral transmittance adjuster, and/or an antifouling agent. 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, so the description is omitted here.

<<Second 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. If 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 set to be measured by the same method as the film thickness of the functional layer 12.

If 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 reduced. Therefore, from the viewpoint of color adjustment, the film thickness of the antistatic layer 93 is preferably 40 nm or more and 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, so the description is omitted here.

<Binder Resin>

The binder resin is preferably selected from (meth)acrylic resins, cellulose resins, urethane resins, vinyl chloride resins, polyester resins, polyolefin resins, polycarbonate, nylon, and polystyrene , And at least one of the group consisting of ABS resin. Among these, from the viewpoint of the hardness or transparency of the adhesive resin, (meth)acrylic resins, urethane resins, and the like are preferred.

As said (meth)acrylic resin, polymethyl methacrylate etc. are mentioned, for example. Moreover, as said cellulose resin, diacetyl cellulose, cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), etc. are mentioned, for example. As said urethane resin, a urethane resin etc. are mentioned, for example.

As said vinyl chloride resin, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, etc. are mentioned, for example. Moreover, as said polyester resin, polyethylene terephthalate etc. are mentioned, for example. Moreover, as said polyolefin resin, polyethylene, polypropylene, etc. are mentioned, for example.

<<The manufacturing method of optical film>>

The optical film 90 can be produced in the following manner, for example. First, by using a coating device such as a bar coater, the first surface 91A of the translucent substrate 91 is coated to obtain the first antistatic layer composition for obtaining the antistatic layer 92 to form the first The coating film of the composition for the antistatic layer.

<Composition for the first antistatic layer>

The composition for the first antistatic layer contains a polymerizable compound that becomes a binder resin after curing, and an antistatic agent. The composition for the first antistatic layer may also optionally contain an ultraviolet absorber, a spectral transmittance adjuster, an antifouling agent, an inorganic particle, a leveling agent, a solvent, and a polymerization initiator. The solvent and the polymerization initiator are the same as the solvent and the polymerization initiator described in the column of the composition for the functional layer, so the description is omitted here.

After forming the coating film of the composition for the first antistatic layer, the coating film is dried by various well-known methods, for example, at a temperature above 30°C and below 120°C for 10 seconds to 120 seconds to evaporate the solvent .

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

After the antistatic layer 92 is formed, a coating device such as a bar coater is used to coat the second surface 91B of the light-transmitting substrate 91 to form the second antistatic layer 93. To form a coating film of the composition for the second antistatic layer.

<Composition for the second antistatic layer>

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

After the coating film of the composition for the second antistatic layer is formed, the coating film is heated at a temperature of, for example, 30° C. or higher and 120° C. or lower for 10 seconds to 120 seconds by various well-known methods to dry and 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 films>>>

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

The optical film 100 includes: a light-transmitting substrate 101; a hard coat layer 102 provided on the side of the first surface 101A of the light-transmitting substrate 101 as a functional layer; and a first antistatic layer 103 (hereinafter, sometimes abbreviated as Is the antistatic layer 103), which is disposed on the side of the hard coat layer 102 opposite to the transparent substrate 101 side; the optical adjustment layer 104, which is disposed on the side of the antistatic layer 103 opposite to the hard coat layer 102 side; And the second antistatic layer 105 (hereinafter, also referred to as the antistatic layer 105 in some cases) is provided on the second surface 101B side, which is the surface opposite to the first surface 101A of the translucent base 101. The physical properties and the like of the optical film 100 are the same as the physical properties and the like of the optical film 100, so the description is omitted here.

The front surface 100A of the optical film 100 becomes the front surface 104A of the optical adjustment layer 104. The back surface 100B of the optical film 100 becomes the surface 105A of the antistatic layer 105 on the opposite side to the surface on the translucent base material 101 side.

<<Translucent substrate and hard coating>>

The light-transmitting substrate 101 is the same as the light-transmitting substrate 91, so the description 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, so the description is omitted here.

<<The first antistatic layer and the second antistatic layer>>

The antistatic layers 103 and 105 are the same as the antistatic layer 93, so the description 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 optical properties such as the color tone or reflectance of the optical film 100. If a substrate containing a polyimide resin is used as a translucent substrate, the translucent substrate will show a yellowish tint. Therefore, the optical adjustment layer 104 uses a substrate containing a polyimide resin as the translucent substrate. 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. If the film thickness of the optical adjustment layer 104 is 30 nm or more, the optical characteristics (transmittance, reflectance, hue) can be adjusted, and if it is 500 nm or less, the deterioration of processing can be suppressed. The film thickness of the optical adjustment layer 104 is determined 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, and still more 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, and therefore, the reflectance of external light can be reduced. 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 determined by setting the refractive index of the wavelength region above 380nm and below 780nm to be constant, so that the reflection spectrum measured by a spectrophotometer can be compared with that of a Fresnel film. The spectrum calculated by the optical model is obtained by fitting. In addition, the refractive index of the optical adjustment layer 104 or the antistatic layer 103 can also be determined by measuring with an Abbe refractometer (product name "NAR-4T", manufactured by Atago) or an ellipsometer after forming a separate layer. Out. In addition, as a method for measuring the refractive index after the optical film 100 is formed, the following method can be used, that is, the optical adjustment layer 104 or the antistatic layer 103 is scraped with a cutter or the like to prepare a powdery sample according to JIS K7142: 2008 The B method (for powder or granular transparent materials) is the Baker line method (the refractive index uses the known Cargille reagent, the sample in the powder state is placed on a glass slide, etc., the reagent is dropped on the sample, and the sample Immerse in the reagent; observe the situation by microscope observation, and use the refractive index of the reagent as the refractive index of the sample that cannot be observed visually due to the difference in refractive index between the sample and the reagent in the bright line (Beck's line) generated in the sample contour 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 difference in refractive index 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 silicon oxide or aluminum oxide. The optical adjustment layer 104 can be formed by, for example, a physical vapor deposition (PVD) method such as a sputtering method or an ion plating method, or an evaporation method such as a chemical vapor deposition (CVD) 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, so the description is omitted here.

<<<Image display device>>>

The optical films 90 and 100 can be incorporated into a foldable image display device for use. Fig. 12 is a schematic configuration diagram of the image display device of this embodiment. As shown in FIG. 12, the image display device 110 faces the observer side, and mainly includes a housing 81 for storing batteries, a protective film 82, a display element 83, a circular polarizer 84, a touch sensor 85, and an optical膜90。 Film 90. A light-transmitting adhesive layer 86 is arranged 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 components are fixed to each other by the adhesive layer 86. In addition, in FIG. 12, the members denoted with the same reference numerals as those in FIG. 9 are the same as those shown in FIG. 9, so the description is omitted.

The optical film 90 is arranged so that the antistatic layer 92 is closer to the observer side than the translucent base 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 this embodiment, the optical film 90 is provided with antistatic layers 92, 93 on both sides of the translucent substrate 91, and the optical film 100 is provided with antistatic layers 103, 105 on both sides of the translucent substrate 101, so that it can suppress Dust and the like adhere to the optical films 90 and 100. Moreover, in the state where the protective film (not shown) is attached to both surfaces of the optical films 90 and 100, even if the protective film is peeled from the optical films 90 and 100, the electrification of the optical films 90 and 100 can be suppressed. Therefore, the yield rate of the assembling steps of the image display device can be improved.

Since the optical adjustment layer is a thin film, the scratch resistance of the optical film can be improved if the optical adjustment layer is not provided. Since the optical film 90 does not have an optical adjustment layer on the antistatic layer 92, the scratch resistance is better than that of the optical film 100 having the optical adjustment layer 104 on the antistatic layer 103.

In the foldable optical film, the binder resin of the hard coating must be selected in a foldable way. Moreover, if an antistatic agent is mixed in the hard coat layer like the optical film 90, an antistatic agent showing good compatibility with the selected binder resin must be used, resulting in fewer options for the antistatic agent. In contrast, in the optical film 100, since the antistatic layer 103 is a layer different from the hard coat layer 102, the options of antistatic agents can be expanded.

[Example]

In order to describe the present invention in detail, examples are given below for description, but the present invention is not limited to these descriptions. In addition, the following "100% solid content conversion value" refers to the value when the solid content in the solvent-diluted product is set to 100%.

<Preparation of composition for optical adjustment layer>

First, each component is blended so as to become the composition shown below, and the composition for optical adjustment layers is obtained.

(Composition 1 for optical adjustment layer)

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

‧Zirconium oxide (average particle size 20nm, manufactured by CIK NanoTek): 15 parts by mass (100% converted value of solid content)

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

(Composition 2 for optical adjustment layer)

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

‧Zirconium oxide (average particle size 20nm, manufactured by CIK NanoTek): 30 parts by mass (100% converted value of solid content)

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

(Composition 3 for optical adjustment layer)

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

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

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

(Composition for optical adjustment layer 4)

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

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

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

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

(Composition 5 for optical adjustment layer)

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

‧Zirconium oxide (average particle size 20nm, manufactured by CIK NanoTek): 30 parts by mass (100% converted value of solid content)

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

<Preparation of composition for antistatic layer>

First, each component is blended so that it becomes the composition shown below, and the composition for antistatic layers is obtained.

(Composition 1 for antistatic layer)

‧Mixture of neopentyl erythritol triacrylate and neopentyl erythritol 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 Corporation): 10 parts by mass

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

(Composition for antistatic layer 2)

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

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

<Composition for Hard Coating>

Each component is blended so that it may become a composition shown below, and the composition for hard-coat layers is obtained.

(Composition 1 for hard coat layer)

‧Aurethane resin (product name "U-6LPA", manufactured by Shinnakamura Chemical Co., Ltd.): 70 parts by mass

‧Aurethane 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% converted value of solid content)

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

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

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

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

(Composition for hard coat 2)

‧Mixture of neopentylerythritol triacrylate and neopentylerythritol 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 is blended so that it may become a composition shown below, and the composition for resin layers is obtained.

(Composition for resin layer 1)

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

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

‧Mixtures of tri-neo-neo-pentaerythritol acrylate, mono- and di-neo-neo-pentaerythritol acrylate, and polyneo-neo-neo- erythritol 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)

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

‧Phenoxyethyl 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 3 for resin layer)

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

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

‧Mixtures of trineopentaerythritol acrylate, mono- and dineopentaerythritol acrylate, and polyneopentol acrylate (product name "Viscoat #802", manufactured by Osaka Organic Chemical Industry Co., Ltd.): 10 parts by mass

‧Mixture of dineopentaerythritol pentaacrylate and dineopentaerythritol 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)

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

‧Phenoxyethyl 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 5 for resin layer)

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

‧Mixture of dineopentaerythritol pentaacrylate and dineopentaerythritol 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>

Prepare a polyimide-based substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) with a refractive index of 1.630 and a thickness of 30μm as a resin substrate, and use a bar coater on one side of the polyimide-based substrate The optical adjustment layer composition 2 is coated on the first surface to form a coating film. After that, 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 with a refractive index of 1.562 and a film thickness of 100 nm. After the second optical adjustment layer is formed, the composition 1 for the optical adjustment layer is coated on the surface of the second optical adjustment layer using a bar coater to form a coating film. After that, 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 with a refractive index of 1.544 and a film thickness of 100 nm. After the first optical adjustment layer is formed, the hard coat layer composition 1 is applied to the surface of the first optical adjustment layer using 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, light source H BULB) was used in the air. The coating film is cured by irradiating ultraviolet rays so that the cumulative light intensity becomes 200mJ/cm ^{2 to} form a hard coat layer with a refractive index of 1.531 and a film thickness of 10 μm. Thereby, an optical film in which the first optical adjustment layer is adjacent to the hard coat layer and the second optical adjustment layer is adjacent to the polyimide-based substrate is obtained. Furthermore, the front surface of the optical film of Example A1 is the surface of the hard coat layer, and the back surface is 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 formed by coating the composition for the hard coat layer and the composition for the optical adjustment layer on PET with a thickness of 50 μm that has not been easily bonded to form a hardened film with a thickness of 1 to 10 μm. , Attach a black polyvinyl chloride insulating tape (such as Yamato vinyl tape NO200-38) with a width larger than the area of the measuring point on the surface (back) of the composition for the uncoated hard coat layer or the composition for the optical adjustment layer of PET -21 38mm width) to prevent back reflection, use a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation), measure the average reflectance of wavelength 380~780nm, use the average reflectance obtained based on the above formula ( 2) And find out. In Examples A2 to A12 and Comparative Examples A1 and A2, the refractive index of each layer was also measured by the same method as in Example A1.

In addition, the film thickness of each layer was taken using a scanning transmission electron microscope (STEM) (product name "S-4800", manufactured by Hitachi High-Technology Co., Ltd.) to take a cross-section of the optical film, and measure 20 locations in the image of the cross-section The film thickness of each layer is the arithmetic average of the film thicknesses of the 20 locations. The cross-sectional photograph of the optical film was taken as follows. First, make a block made by embedding an optical film cut out of 1mm×10mm with an embedding resin, and cut out a uniform thickness of 70nm or more and 100nm or less from the block by a general slicing method.的片。 The slice. The production of slices is done using "Ultratome Microtome EM UC7" (Leica Microsystems Co., Ltd.), etc. Then, the uniform slice without holes or the like is used as a measurement sample. Thereafter, a scanning transmission electron microscope (STEM) was used to take a cross-sectional photograph of the measurement sample. When the cross-sectional photograph was taken, the detector was set to "TE", the acceleration voltage was set to "30kV", and the emission current was set to "10μA" for STEM observation. Regarding the magnification, while adjusting the focal length and distinguishing or observing each layer by contrast and brightness, adjust appropriately from 5000 to 200,000 times. Furthermore, when shooting the cross-sectional photo, set the aperture to "beam detection aperture 3", the objective lens aperture to "3", and the W.D. to "8mm". 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 Example A2, a third optical adjustment layer with a refractive index of 1.536 and a film thickness of 100 nm was formed on the surface of the polyimide-based substrate opposite to the second optical adjustment layer side. The optical film was obtained in the same manner as in Example 1. The third optical adjustment layer is formed by applying the composition 3 for the optical adjustment layer to the second surface of the polyimide-based substrate using a bar coater to form a coating film. The coating film is heated at 70°C for 1 minute to evaporate the solvent in the coating film. Using an ultraviolet irradiation device (manufactured by Fusion UV System Japan, light source H BULB), the cumulative light quantity in the air becomes 100mJ/cm ² The method irradiates ultraviolet rays to harden the coating film. Furthermore, 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 Example A3, except that the film thickness of the first optical adjustment layer was 200 nm, an optical film was obtained in the same manner as in Example A1.

<Example A4>

In Example A4, except that the film thickness of the second optical adjustment layer was 200 nm, an optical film was obtained in the same manner as in Example A1.

<Example A5>

In Example A5, an optical film was obtained in the same manner as in Example A1 except that the composition 4 for an optical adjustment layer was used instead of the composition 1 for an optical adjustment layer. Furthermore, the refractive index of the first optical adjustment layer formed using the composition 4 for the optical adjustment layer was 1.547.

<Example A6>

In Example A6, an optical film was obtained in the same manner as in Example A1 except that the composition 5 for an optical adjustment layer was used instead of the composition 2 for an optical adjustment layer. Furthermore, the refractive index of the second optical adjustment layer formed using the composition 5 for the optical adjustment layer was 1.563.

<Example A7>

In Example A7, an optical film was obtained in the same manner as in Example A1 except that the film thickness of the hard coat layer was set to 20 μm.

<Example A8>

In Example A8, except that the film thickness of the hard coat layer was set to 40 μm, an optical film was obtained in the same manner as in Example A1.

<Example A9>

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

<Example A10>

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

<Example A11>

In Example A11, a polyester-based substrate (product name "U403", manufactured by Toray Corporation) with a refractive index of 1.654 and a thickness of 23 μm was used instead of the polyimide-based substrate. Way to obtain an optical film.

<Example A12>

Prepare a polyimide-based substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) with a refractive index of 1.630 and a thickness of 30μm as a resin substrate. The optical adjustment layer composition 1 is applied to the first side of one side to form a coating film. After that, the formed coating film was heated at 90°C for 1 minute to evaporate the solvent in the coating film to form a polyimide-based substrate with a refractive index of 1.544 and a film thickness of 100nm. 1 Optical adjustment layer. After the first optical adjustment layer is formed, the hard coat layer composition 1 is applied to the surface of the first optical adjustment layer using 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, and an ultraviolet irradiation device (manufactured by Fusion UV System Japan, light source H BULB) was used in the air. The coating film is cured by irradiating ultraviolet rays so that the cumulative light intensity becomes 200mJ/cm ^{2 to} form a hard coat layer with a refractive index of 1.531 and a film thickness of 10 μm. Thereby, an optical film in which the first optical adjustment layer is adjacent to the hard coat layer and the polyimide-based substrate is obtained. Furthermore, 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 Example A13, a polyimide-based substrate with a refractive index of 1.662 and a thickness of 30μm (product name "THD-30", manufactured by Kolon) was used instead of the polyimide-based substrate. An optical film was obtained in the same manner as in Example A12.

<Example A14>

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

<Example A15>

In Example A15, a polyester-based substrate (product name "U403", manufactured by Toray Corporation) with a refractive index of 1.654 and a thickness of 23 μm was used instead of the polyimide-based substrate. Except for this, the same as in Example A12 was used. Way to obtain an optical film.

<Example A16>

In Example A16, a resin layer was formed on the surface of the polyimide-based substrate opposite to the surface of the first optical adjustment layer in the following manner. Except for this, the optical fiber was obtained in the same manner as in Example A12. membrane. When forming the resin layer, first, the resin layer composition 1 is applied to the surface of the polyimide-based substrate opposite to the first optical adjustment layer side using 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 an ultraviolet irradiation device (manufactured by Fusion UV System Japan, light source H BULB) was used to accumulate in the air. Ultraviolet rays were irradiated so that the amount of light became 1200 mJ/cm ^{2 to} harden the coating film to form a resin layer made of urethane resin with a refractive index of 1.504 and a film thickness of 200 μm.

<Example A17>

In Example A17, except that the film thickness of the resin layer was 50 μm, an optical film was obtained in the same manner as in Example A16.

<Example 18>

In Example A18, except that the film thickness of the resin layer was set to 300 μm, an optical film was obtained in the same manner as in Example A16.

<Example A19>

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

<Example A20>

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

<Example A21>

In Example 21, except that the film thickness of the resin layer was 50 μm, an optical film was obtained in the same manner as in Example A20.

<Example A22>

In Example A22, except that the film thickness of the resin layer was set to 300 μm, an optical film was obtained in the same manner as in Example A20.

<Example A23>

In Example A23, a third optical adjustment layer with a refractive index of 1.536 and a film thickness of 100 nm was formed between the polyimide-based substrate and the resin layer. An optical film was obtained in the same manner as in Example A16, except that the third optical adjustment layer was formed. The third optical adjustment layer is formed by applying the composition 3 for the optical adjustment layer to the second surface of the polyimide-based substrate using a bar coater before forming the resin layer to form a coating. For the formed coating film, heat it at 70°C for 1 minute to evaporate the solvent in the coating film. Use an ultraviolet irradiation device (manufactured by Fusion UV System Japan, light source H BULB) to accumulate in the air Ultraviolet rays are irradiated so that the amount of light becomes 100mJ/cm ^{2 to harden the coating film.} After forming the third optical adjustment layer, the resin layer was formed on the surface of the third optical adjustment layer in the same manner as in Example A16. Furthermore, 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 Example A24, a resin layer made of urethane resin with a refractive index of 1.504 and a film thickness of 200 μm was formed on the surface opposite to the surface of the polyimide-based substrate of the third optical adjustment layer. 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>

Prepare a polyimide-based substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) with a refractive index of 1.630 and a thickness of 30μm as a resin substrate, and use a bar coater on one side of the polyimide-based substrate The hard coat layer composition 1 was applied to the first surface 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, light source H BULB) was used in the air. The coating film is cured by irradiating ultraviolet rays so that the cumulative light amount becomes 200mJ/cm ² to form a hard coat layer with a film thickness of 10 μm, thereby obtaining an optical film in which the hard coat layer is adjacent to the polyimide-based substrate. Furthermore, 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 substrate opposite to the first surface.

<Comparative Example A2>

In Comparative Example A2, except that the film thickness of the hard coat layer was 50 μm, an optical film was obtained in the same manner as in Comparative Example A1.

<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 opposite side to the hard-coat layer side as follows. When forming the resin layer, first, the resin layer composition 1 is applied to the surface of the polyimide-based substrate opposite to the hard-coat layer side using 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 an ultraviolet irradiation device (manufactured by Fusion UV System Japan, light source H BULB) was used to accumulate in the air. Ultraviolet rays were irradiated so that the amount of light became 1200 mJ/cm ^{2 to} harden the coating film to form a resin layer made of urethane resin with a refractive index of 1.504 and a film thickness of 30 μm.

<Comparative Example A4>

In Comparative Example A4, except that the film thickness of the resin layer was 350 μm, an optical film was obtained in the same manner as in Comparative Example A3.

<Comparative Example A5>

In Comparative Example A5, except that the resin layer composition 4 was used instead of the resin layer composition 1 to form a resin layer with a film thickness of 200 μm, an optical film was obtained in the same manner as in Comparative Example A3. Furthermore, the refractive index of the resin layer formed using the composition 4 for the 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 with a film thickness of 200 μm. Moreover, the refractive index of the resin layer formed using the composition 5 for resin layers was 1.509.

<Comparative Example A7>

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

<Interference fringe evaluation>

In the optical films of Examples A1 to A24 and Comparative Examples A1 to A7, it was evaluated whether interference fringes were observed. Specifically, a black acrylic sheet to prevent back reflection is attached to the back of the optical film via a transparent adhesive, and light is irradiated to each optical film from the front side of the optical film, and it is visually observed whether interference fringes are confirmed. As the light source, a three-wavelength tube fluorescent lamp is used. The interference fringe generation is evaluated according to the following criteria.

◎: No interference fringes are confirmed.

○: Although some interference fringes are confirmed, there is no problem in actual use.

×: Interference fringes are clearly confirmed.

<Continuous foldability and adhesion before durability test>

The optical films of Examples A1 to A24 and Comparative Examples A1 to A7 were cut into 30mm×100mm rectangles to prepare samples, and the samples were mounted on a durability testing machine (product name "DLDMLH-FS", manufactured by Yuasa System) as follows ), that is, the short side (30mm) side of the sample is fixed separately with the fixing part, and as shown in Figure 2(C), the minimum distance between the two opposing sides becomes 10mm, and the front side of the sample is performed 10,000 times Side-folding 180° continuous folding test (a test of folding with the hard coat layer as the inside and the substrate, the third optical adjustment layer or the resin layer as the outside), to investigate whether there is no occurrence between the substrate and the hard coat layer Protrusion (clearance), and investigate whether there is no crack or fracture in the bent part. The results of the continuous folding test are divided into continuous folding properties and adhesion properties, and evaluations are made based on the following criteria. In addition, the samples used in the continuous folding test were obtained from the optical film cutting before the following durability test.

(Continuous foldability)

◎: In the continuous folding test, no cracks or breaks occurred in the bent portion.

○: In the continuous folding test, some cracks or breaks occurred in the bent part, but there is no problem in actual use.

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

(Adhesion)

◎: In the continuous folding test, no swelling was generated between the substrate and the hard coat layer.

○: In the continuous folding test, a little swelling was generated between the base material and the hard coat layer, but the level was no problem in actual use.

×: In the continuous folding test, swelling was clearly generated between the base material and the hard coat layer.

<Continuous foldability and adhesion after durability test>

For the optical films of Examples A1 to A24 and Comparative Examples A1 to A7, a durability test was performed in which the optical film was placed in an environment of 60°C and a relative humidity of 90% for 12 hours, and the optical film after the durability test was cut into 30mm ×100mm rectangle to make a sample, install the sample on a durability testing machine (product name "DLDMLH-FS", manufactured by Yuasa System) in the following way, that is, fix the short side (30mm) side of the sample with the fixing part respectively , And as shown in Figure 2(C), the minimum distance between the two opposing sides becomes 10mm, and the continuous folding test is performed 10,000 times to fold the front side of the sample 180° (with the hard coat as the inner side and the base material , The third optical adjustment layer or the resin layer becomes the outer side of the folding test), investigate whether there is no bulge (gap) between the substrate and the hard coat layer, and whether there is no crack or break in the bent part. The results of the continuous folding test are divided into continuous folding properties and adhesion properties, and evaluations are made based on the following criteria.

(Continuous foldability)

◎: In the continuous folding test, no cracks or breaks occurred in the bent portion.

○: In the continuous folding test, some cracks or breaks occurred in the bent part, but there is no problem in actual use.

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

(Adhesion)

◎: In the continuous folding test, no swelling was generated between the substrate and the hard coat layer.

○: In the continuous folding test, a little swelling was generated between the base material and the hard coat layer, but the level was no problem in actual use.

×: In the continuous folding test, swelling was clearly generated between the base material and the hard coat layer.

<Pencil Hardness>

Based on JIS K5600-5-4: 1999, the pencil hardness of the front surface of the optical films of Examples A1 to A24 and Comparative Examples A1 to A7 were measured respectively. The pencil hardness test is carried out by fixing an optical film cut out with a size of 30mm×100mm on a glass plate using Cellotape (registered trademark) manufactured by Nichiban Co., Ltd. without bending or wrinkles. For the front of the optical film, a pencil hardness tester (product name "Pencil Scratch Film Hardness Tester (Electric Type)", manufactured by Toyo Seiki Seisakusho Co., Ltd.) is used, with a pencil (product name "Uni", Mitsubishi) (Made by Pencil Co., Ltd.) while applying a load of 750g, the pencil moves at a moving speed of 1mm/sec. The pencil hardness is set to the highest hardness that does not cause damage to the front surface of the optical film in the pencil hardness test. In addition, when measuring the pencil hardness, use multiple pencils with different hardness to perform the pencil hardness test 5 times for each pencil, and penetrate the front surface of the optical film under a fluorescent lamp 4 times out of 5 times. When the damage is not recognized on the front surface of the optical film during observation, it is judged that the pencil of the hardness has not caused damage to the front surface of the optical film. In addition, as an optical film, the optical film before the said durability test was used.

<Peeling resistance to electrification>

A protective film was attached to the front surface of the optical film of Examples A1 to A24 and Comparative Examples A1 to A7, and the peeling charge amount when the protective film was peeled off from the front surface of the optical film was measured, and the peeling charge amount was evaluated. Specifically, a protective film with an adhesive layer (product name "SAT2038T-JSL", manufactured by SUN A. KAKEN) was attached to the front surface of the optical film, and it was removed from the optical film under an environment of 23°C and a relative humidity of 50%. Peel off the protective film 180° from the front side at a peeling speed of 300mm/min. Use an electrostatic measuring device (product name "KSD-0103", manufactured by Kasuga Electric Co.) to measure the potential of the front side of the optical film at a distance of 50mm from the front side. , Determine the peeling charge. The peeling charge amount was measured 10 times on the front surface of the optical film, and set as the arithmetic average of the peeling charge amount obtained from the 10 measurements. The evaluation criteria are as follows. In addition, as an optical film, the optical film before the said durability test was used.

○: The peeling charge on the front side of the optical film is within the range of -10kV~10kV.

×: The peeling charge on the front side of the optical film exceeds ±10kV.

<Saturation Band Voltage>

The saturation charged voltage of the front surface of the optical films of Examples A1 to A24 and Comparative Examples A1 to A7 were respectively measured. Specifically, in an environment of 23°C and a relative humidity of 50%, a voltage of 10kV is applied at a distance of 50mm from the front surface of the optical film cut out with a size of 100mm×100mm, and a charged charge attenuation tester (product name "H-0110", manufactured by Shishido Electrostatic Co., Ltd.), to measure the saturated charged voltage of the front surface of the optical film. The saturation band voltage is set as the arithmetic average of the values obtained by measuring 3 times. In addition, as an optical film, the optical film before the said durability test was used.

<Surface resistance value>

In the optical films of Examples A1 to A24 and Comparative Examples A1 to A7, a resistivity meter (product name "Hiresta-UP MCP-HT450", manufactured by Mitsubishi Chemical Analytech, probe: URS) was used to measure the resistance value of the surface. The surface resistance values are randomly measured at 10 locations on the front surface resistance values of the optical film cut out with a size of 50mm×50mm, and the arithmetic average of the measured surface resistance values of the 10 locations is used. In addition, as an optical film, the optical film before the said 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 respectively. Specifically, first, the optical film cut out to a size of 50mm×50mm is placed on a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation) so that the substrate side of the optical film becomes the light source side. , Light source: tungsten filament lamp and deuterium lamp). The optical film is free of defects (incorporation of foreign matter), no cracks, no wrinkles, and no stains, and is kept in a spectrophotometer in a flat state without curling. In this state, under the following measurement conditions, measure the transmittance at the lowest 5 points between the wavelengths of 300nm to 780nm and 1nm before and after, and calculate the average value. Then, read the above-mentioned transmittance measurement data on the monitor connected to the UV-2450, and check "YI" in the calculation item to obtain YI. In addition, as an optical film, the optical film before the said durability test was used.

(Measurement conditions)

‧Wavelength range: 300nm~780nm

‧Scan 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

‧Auto zero: implement at 550nm after scanning 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 Research Institute Co., Ltd.) was used to measure total light in accordance with JIS K7361-1: 1997 Penetration rate. Regarding the above-mentioned total light transmittance, the above-mentioned total light transmittance is cut out in a size of 50mm×100mm, and the hard coat side becomes the non-light source side without curls or wrinkles and no fingerprints or dust. The method setting is to measure one optical film 3 times, and use the arithmetic average of the values obtained from the 3 measurements. In addition, as an optical film, the optical film before the said durability test was used.

<Measurement of G', G", tanδ>

The shear storage modulus G', shear loss modulus G", and shear loss tangent tanδ of the optical films of Examples A16 to A24 and Comparative Examples A3 to A6 were measured. Specifically, first, the optical film was punched It has a rectangular shape of 10 mm x 5 mm and is used as a sample. Next, two samples of this sample are prepared and attached to the measurement jig of a dynamic viscoelasticity measuring device (product name "Rheogel-E4000", manufactured by UBM Co., Ltd.). Specifically, the solid shearing jig has a metal solid shearing plate with a thickness of 1mm and two L-shaped metal pieces arranged on both sides of the solid shearing plate. The solid shearing plate and the L-shaped metal A sample is sandwiched between the pieces, and another sample is sandwiched between the solid shear plate and another L-shaped metal piece. In this case, the sample is sandwiched so that the resin layer becomes the solid shear plate side and the hard coat layer becomes the L-shaped metal part side. Then, the L-shaped metal parts are fastened with screws to fix the sample. Then, after installing a tensile test chuck composed of an upper chuck and a lower chuck on the dynamic viscoelasticity measuring device (product name "Rheogel-E4000", manufactured by UBM Co., Ltd.), the solid shearing jig was used The distance between the chucks is 20mm between the upper chuck and the lower chuck. Then, the set temperature was set to 25°C and the temperature was increased at 2°C/min. In this state, the solid shear plate is fixed on one side, and longitudinal vibration with a strain of 1% and a frequency of 500 Hz or more and 1000 Hz or less is applied to the two L-shaped metal parts, and the dynamic viscoelasticity of the solid is measured at 25°C. Measure the shear storage modulus G', shear loss modulus G" and shear loss tangent tanδ of the optical film. Here, the shear storage modulus G'of the optical film in the frequency region above 500 Hz and below 1000 Hz, The shear loss modulus G" and shear loss tangent tanδ are set to the values obtained by the following method. The longitudinal vibration of the frequency 500Hz, 750Hz, 950Hz is applied to the L-shaped metal parts, and the shear of the optical film is measured at each frequency. Cut storage modulus G', shear loss modulus G" and shear loss tangent tanδ, and obtain the arithmetic average of these shear storage modulus G', shear loss modulus G" and shear loss tangent tanδ , And then repeat the measurement three times, and further carry out the arithmetic average of the three arithmetic averages obtained. In addition, as an optical film, the optical film before the said durability test was used.

<Impact resistance test>

Place the optical films of Examples A16 to A24 and Comparative Examples A3 to A6 directly on the surface of the soda glass with a thickness of 0.7mm so that the soda glass side becomes the resin layer side, and perform the following impact resistance test A three times each, namely, Drop an iron ball with a weight of 100g and a diameter of 30mm from a height of 30cm onto the surface of the hard coating of the optical film. In addition, on the soda glass with a thickness of 0.7mm, the soda glass side becomes the resin layer side, and the adhesive sheet (product name "high transparency double-sided tape 8146-2", manufactured by 3M company) with a thickness of 200μm is placed and implemented. The optical films of Examples A16~A24 and Comparative Examples A3~A6 were subjected to the following impact resistance test B three times each, that is, an iron ball with a weight of 100g and a diameter of 30mm was dropped from a position of 30cm in height to the hard coating of the optical film surface. Furthermore, in the impact resistance tests A and B, the drop position of the iron ball was changed every time. Then, in the optical film after the impact resistance test A, it was visually evaluated whether or not dents were generated on the surface of the hard coat layer, and whether or not cracking occurred in the soda glass was evaluated. In addition, in the optical film after impact resistance test B, it was visually evaluated whether or not dents were generated on the surface of the hard coat layer. The evaluation results are as follows.

(Evaluation of depression on the surface of the hard coating)

○: In both cases of observing the hard coat from the front and obliquely, no dent was confirmed on the surface of the hard coat.

△: When observing the hard coat from the front, no dents are observed on the surface of the hard coat, but when obliquely observed, dents are confirmed on the surface of the hard coat.

×: When observing the hard coating from the front and obliquely, obvious dents were observed on the surface of the hard coating.

(Evaluation of rupture of soda glass)

◎: The soda glass is not broken.

○: The soda glass is damaged but not broken.

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

X: Cracks occurred in the soda glass all three times.

Below, 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, the optical adjustment layer adjacent to the hard coating layer was not provided between the polyimide-based substrate and the hard coating layer, so interference fringes were clearly observed. In addition, in the optical film of Comparative Example A2, since the film thickness of the hard coat layer is thick, the generation of interference fringes is suppressed, but the continuous foldability is poor. In addition, in the optical film of Comparative Example A7, the first optical adjustment layer adjacent to the hard coating layer is provided between the polyimide-based substrate and the hard coating layer. However, the thickness of the first optical adjustment layer is larger Thick, so continuous folding is poor. In contrast, in the optical films of Examples A1 to A24, the first optical adjustment layer adjacent to the hard coating layer is provided between the various substrates and the hard coating layer, thereby suppressing the generation of interference fringes and achieving continuous foldability Also excellent. Furthermore, in the optical films of Examples A1 to A24, the film thickness of the first optical adjustment layer is thinner than that of the optical film of Comparative Example A7, so interference fringes are suppressed more than the optical film of Comparative Example A7. In addition, from the adhesion evaluation after the heat resistance test, it can be seen that in the optical films of Examples A1 to A11, since the second optical adjustment layer is provided, the adhesion between the substrate and the first optical adjustment layer is less than that of the second optical film. The optical film of Examples A12~A24 of the adjustment layer is improved.

In addition, in the optical films of Examples A1 and A8, the short side (30mm) side of the sample made by cutting a rectangle of 30mm×100mm was fixed in parallel so that the distance between the opposite sides of the sample became 10mm. The fixed part arranged on the ground, in the state of folding the optical film, was subjected to a folding static test at 70°C for 12 hours. Then, after the folding and standing test, the fixed part was removed from the side of one side to release the folded state. After 30 minutes at room temperature, the angle at which the optical film naturally opened, that is, the opening angle, was measured (refer to Figure 3). (B)). As a result, the opening angle of the optical film of Example A1 is more than 100°, which is greater than the opening angle of the optical film of Example A8. In addition, as the opening angle, the folding and standing test was performed in two cases of folding with the hard coat layer on the inside and the hard coat layer on the outside, and the smaller angle was used.

Furthermore, in the optical film of Comparative Example A3, the resin layer was too thin to absorb the impact. In the impact resistance test A, the soda glass cracked, and in the impact resistance test B, it followed The plastic deformation of the adhesive sheet causes a large amount of depression on 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 foldability was poor. 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. In the impact resistance test A, the soda glass was slightly broken. In Comparative Example A6 In the optical film, because the shear storage modulus G'is too large and the shear loss modulus G" is too small, it cannot absorb the impact. In the impact resistance test A, there are also cases of cracking in the soda glass, and the foldability It is also poor. In contrast, in the optical films of Examples A16 to A24, the impact resistance test could not be confirmed due to the good balance between the thickness of the resin layer, the shear storage modulus G', and the shear loss modulus G" The surface of the hard coating layer after A and B is dented, and there is no crack in the soda glass.

In addition, using the optical films of Examples A1 to A24 before and after the durability test, respectively, samples of the same size as the above were produced, and the minimum distance between the two opposing sides of the sample was 3mm, the same as the above Place the sample on a durability testing machine (product name "DLDMLH-FS", manufactured by Yuasa System), and perform a continuous folding test in which the front side of the sample is folded 180° for 10,000 times (the hard coat layer is used as the inner side and the base material, The third optical adjustment layer or the resin layer is folded in such a way that it is inside), the continuous foldability and adhesion before the durability test and the continuous foldability and adhesion after the durability test are respectively evaluated according to the same evaluation criteria as the above The performance was evaluated, and as a result, in the optical films of Examples A1 to A15, the continuous foldability and adhesion before the aforementioned durability test and the continuous foldability and adhesion after the aforementioned durability test were good.

In addition, the optical films of Examples A1 to A24 and Comparative Examples A1 to A6 before and after the durability test were used to prepare samples of the same size as the above, and the minimum distance between the two opposing sides of the sample was 30mm In the same way as above, the sample was mounted on a durability tester (product name "DLDMLH-FS", manufactured by Yuasa System), and a continuous folding test (with a hard coat layer) was performed by folding the back side of the sample by 180° for 10,000 times. The test of folding so that the substrate, the third optical adjustment layer or the resin layer becomes the inner side), the continuous foldability and adhesion before the durability test and after the durability test were respectively evaluated according to the same evaluation criteria as the above The continuous foldability and adhesion were evaluated, and the results were the same as those in Table 1.

In addition, the Martens hardness of the hard coat of the optical film of the optical films of Examples A1 to A24 was measured. As a result, the Martens hardness of the hard coat was 650 MPa. The Martens hardness is based on the "TI950 TriboIndenter" manufactured by HYSITRON. Under the following measurement conditions, the Berkovich indenter (triangular cone) is pressed into 500nm at the center of the cross section of the hard coating, and kept fixed. After the residual stress is relieved, the load is unloaded, the maximum load after the relaxation is measured, and the maximum load P _max (μN) and the recessed area A (nm ² ) with a depth of 500 nm are used to calculate from P _max /A. The Martens hardness is the arithmetic mean of the values obtained by measuring 10 locations.

(Measurement conditions)

‧Load speed: 10nm/sec

‧Holding time: 5 seconds

‧Load unloading speed: 10nm/sec

‧Measuring temperature: 25℃

On the surface of the polyimide-based substrate of Example A1 opposite to the surface of the first optical adjustment layer, an antistatic agent containing a quaternary ammonium salt (product name "1SX-3000", Taisei Fine Chemical Co., Ltd.) 100 parts by mass (100% conversion value of solid content), 4 parts by mass of photopolymerization initiator (product name "Irg184", manufactured by BASF Japan), and 150 parts by mass of solvent (MIBK) for the antistatic layer The composition is coated with the composition for the antistatic layer using 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 with a film thickness of 100 nm, thereby obtaining an optical film. Furthermore, the front side of the optical film is the surface of the hard coat layer, and the back side is the surface of the antistatic layer. Then, a protective film was attached to the front and back of the optical film, and the peeling charge amount when the protective film was peeled from the front and back of the optical film was measured. The peeling charge amount of the front and back of the optical film was -10kV~10kV, respectively. Within the range.

<<Example B and Comparative Example B>>

<Example B1>

Prepare a polyimide substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) with a thickness of 50μm as a translucent substrate, and apply a bar coater to the first side of the polyimide substrate. The composition 1 for the 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, light source H BULB) was used in the air. The coating film is cured by irradiating ultraviolet rays so that the cumulative light amount becomes 200 mJ/cm ^{2 to} form a first antistatic layer with a film thickness of 20 μm as an antistatic hard coat layer. Then, the antistatic layer composition 2 was applied to the second surface of the polyimide substrate opposite to the above-mentioned first surface using a bar coater to form a coating film. The formed coating film is heated at 70°C for 1 minute to evaporate the solvent in the coating film to form a second antistatic layer with a film thickness of 100nm, which is formed on both sides of the polyimide substrate Optical film with antistatic layer. Furthermore, the front surface of the optical film of Example B1 is the surface of the first antistatic layer, and the back surface is the surface of the second antistatic layer. In addition, the film thickness of the antistatic layer was taken by using a scanning electron microscope (SEM) to photograph the cross section of the antistatic layer, and the film thickness of the antistatic layer at 20 locations was measured in the image of the cross section, and the film thickness of the 20 locations was used. The arithmetic mean of thick. In Examples B2, 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 Example B2, except that the film thickness of the second antistatic layer was 10 μm, an optical film was obtained in the same manner as in Example B1. Furthermore, the front surface of the optical film of Example B2 is the surface of the first antistatic layer, and the back surface is the surface of the second antistatic layer.

<Example B3>

Prepare a polyimide substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) with a thickness of 50μm as a translucent substrate, and apply a bar coater to the first side of the polyimide substrate. The hard coat layer composition 2 is 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, light source H BULB) was used in the air. The coating film is cured by irradiating ultraviolet rays so that the cumulative light amount becomes 200 mJ/cm ² to form a hard coat layer with a film thickness of 20 μm. Then, the antistatic layer composition 2 is 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 with a film thickness of 80 nm. After that, in the high-frequency sputtering device, a high-frequency power of 13.56MHz and a power of 5kW is applied to the electrode to generate discharge in the chamber, and a film thickness of 100nm and refractive index is formed on the surface of the first antistatic layer It is a silicon dioxide vapor-deposited layer of 1.46 as an optical adjustment layer. After that, the antistatic layer composition 2 was applied to the second surface of the polyimide substrate opposite to the above-mentioned first surface using a bar coater to form a coating film. The formed coating film is heated at 70°C for 1 minute to evaporate the solvent in the coating film to form a second antistatic layer with a film thickness of 80nm, which is formed on both sides of the polyimide substrate Optical film with antistatic layer. Furthermore, the front surface of the optical film of Example B3 is the surface of the silicon dioxide vapor-deposited layer, and the back surface is the surface of the second antistatic layer.

<Comparative Example B1>

Prepare a polyimide substrate (product name "Neopulim", manufactured by Mitsubishi Gas Chemical Co., Ltd.) with a thickness of 50μm as a translucent substrate, and apply a bar coater to the first side of the polyimide substrate. The hard coat layer composition 2 is 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, light source H BULB) was used in the air. The coating film was cured by irradiating ultraviolet rays so that the accumulated light amount became 200 mJ/cm ² to form a hard coat layer with a film thickness of 20 μm to obtain an optical film. Furthermore, 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 and the first surface as one surface was the opposite side.

<Comparative Example B2>

In Comparative Example B2, except that the second antistatic layer was not formed, an optical film was obtained in the same manner as in Example B1. Furthermore, 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>

In Comparative Example B3, the second antistatic layer and the silicon dioxide vapor-deposition layer were not formed, except that the optical film was obtained in the same manner as in Example B3. Furthermore, the front surface of the optical film of Comparative Example B3 is the surface of the first antistatic layer, and the back surface is the surface of the polyimide substrate opposite to the first surface.

<Peeling resistance to electrification>

A protective film was attached to the front and back surfaces 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 from the front and back of the optical film was measured, and the peeling charge amount was evaluated. Specifically, a protective film with an adhesive layer (product name "Sunytect series", manufactured by SUN A. KAKEN) is attached to the front and back of the optical film, and the optical film is removed from the optical film at 23°C and 50% relative humidity. The front and back of the protective film are peeled 180° at a peeling speed of 10mm/sec. Use an electrostatic potential measuring device (product name "KSD-0103", manufactured by Kasuga Electric Co.) to measure the distance from the front and back of 50mm. The potential of the front and back of the optical film was measured to measure the peeling charge. The peeling charge amount was measured 10 times on both sides of the optical film, and set as the arithmetic average of the peeling charge amount obtained by the 10 measurements. The evaluation criteria are as follows.

○: The peeling charge amount of the front and back of the optical film are both within the range of 0kV~5kV.

×: Either the peeling charge amount of the front and back of the optical film exceeds 5kV.

<Surface resistance value>

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

<Continuous Foldability>

The optical films of Examples B1 to B3 and Comparative Examples B1 to B3 were cut into 30mm×100mm rectangles to prepare samples, and the samples were mounted on a durability tester (product name "DLDMLH-FS", manufactured by Yuasa System) as follows ), that is, the short side (30mm) side of the sample is respectively fixed by the fixing part, and the minimum distance between the two opposing sides becomes 3mm, and the continuous folding test is carried out by folding the front side of the sample 180° for 100,000 times ( Fold the first antistatic layer, the optical adjustment layer or the hard coat layer on the inside and the second antistatic layer or the polyimide substrate on the outside) to investigate whether there are no cracks or breaks in the bent part. In addition, new samples made in the same manner as above for the optical films of Examples B1 to B3 and Comparative Examples B1 to B3 were installed in the durability tester in the same manner as above, and the back side of the samples was folded 180 times in the same manner as above. ° Continuous folding test (a test that the first antistatic layer, optical adjustment layer or hard coat layer becomes the outer side and the second antistatic layer or polyimide substrate becomes the inner side) to investigate whether the bending part is not Cracks or breaks occur. The results of the continuous folding test were evaluated according to the following criteria.

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

×: In any continuous folding test, cracks or breaks occurred in the bent portion.

<Pencil Hardness>

The front surface of the optical films of Examples B1 to B3 and Comparative Examples B1 to B3 were subjected to a pencil hardness test and evaluated based on JIS K5600-5-4:1999. The pencil hardness test is carried out by using a 2H pencil, using the Cellotape (registered trademark) manufactured by Nichiban Corporation to cut an optical film with a size of 50mm×100mm on the glass plate without bending or wrinkles. Fix it. In this state, while applying a load of 1 kg to the pencil, move the pencil at a speed of 1 mm/sec. The pencil hardness test was performed 5 times. The front side of the optical film after the pencil hardness test was penetratively observed under a fluorescent lamp. In the 5 times of the study, no damage was recognized on the surface. The evaluation criteria are as follows.

○: In the case of a 2H pencil, no damage was visually recognized on the surface.

×: In the case of a 2H pencil, damage is recognized on the surface.

<Saturation Band Voltage>

Under the same measurement conditions as in Example A, the saturation charged voltages of the front and back surfaces of the optical films of Examples B1 to B3 and Comparative Examples B1 to B3 were respectively measured.

<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 is less than 1.5.

○: YI is 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 with a wavelength of 380 nm to 780 nm was measured and evaluated. The visual reflectance is measured by using a spectrophotometer (product name "UV-2450", manufactured by Shimadzu Corporation, light source: tungsten lamp and deuterium lamp), and the front side of the optical film cut into a size of 5cm×10cm. The irradiation wavelength is 380nm The light of ~780nm is measured by the light of wavelength 380nm~780nm reflected from the optical film. Specifically, light with an incident angle of 5 degrees is irradiated from the front side of each optical film, and the reflected light in the regular reflection direction reflected by each optical film is received, and the reflectance in the wavelength range of 380nm~780nm is measured. The software that converts the brightness perceived by the eyes (such as the software built in UV-2450) calculates the visual reflectance. The evaluation criteria are as follows.

◎: The visual reflectance is 3% or less.

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

△: The visual reflectance exceeds 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 resistance when the protective film was peeled off was poor. In contrast, in the optical films of Examples B1 to B3, since the first antistatic layer and the second antistatic layer are provided, the peeling resistance when the protective film is peeled off is excellent.

In addition, in the optical films of Examples B1 to B3, the short side (30mm) side of the sample made by cutting into a rectangle of 30mm×100mm was fixed in parallel so that the distance between the opposite sides of the sample became 3mm. The fixed part arranged on the ground, in the state of folding the optical film, was subjected to a folding and standing test at 70°C for 240 hours. Then, after the folding and standing test, the fixed part was removed from the edge of one side to release the folded state. After 30 minutes at room temperature, the angle at which the optical film was naturally opened, that is, the opening angle, was measured. Example B2 The opening angle of the optical film is more than 100°, which is greater than the opening angle of the optical film of Examples B1 and B3. In addition, as the opening angle, when folding with the first antistatic layer on the inside and when folding with the first antistatic layer on the outside, a folding static test was performed, and the angle was smaller. By.

In addition, under the same conditions as in Example A, the Martens hardness of the first antistatic layer and the hard coating of the third optical film of the optical films of Examples B1 and B2 were measured, and the results showed that the first antistatic layer and the hard coating The Martens hardness of the layer is 612MPa.

10‧‧‧Optical film

10A、12A‧‧‧Front

10B‧‧‧Back

11‧‧‧Resin substrate

11A‧‧‧Side 1

11B‧‧‧Side 2

12‧‧‧Functional layer

13‧‧‧The first optical adjustment layer

14‧‧‧Second optical adjustment layer

15‧‧‧The third optical adjustment layer

15A‧‧‧The surface of the optical adjustment layer and the resin substrate side is the opposite side

Claims (20)

An optical film, which is used in an image display device and is foldable, and is provided with: a resin substrate, which is selected from the group consisting of polyimide resin, polyimide resin, polyimide resin and Consisting of one or more resins in the group consisting of polyester resins; a functional layer provided on the first surface side of the resin substrate; a first optical adjustment layer provided on the resin substrate and the function Between the layers and adjacent to the functional layer; and a resin layer provided on the second surface side of the resin substrate opposite to the first surface side and having a film thickness of 50 μm or more and 300 μm or less; the optical film The shear storage modulus G'at 25℃ and above 500Hz and below 1000Hz in the frequency region exceeds 200MPa and below 1200MPa, and the above-mentioned optical film is sheared at 25℃ and above 500Hz and below 1000Hz in the frequency region The 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 between the resin substrate and the resin layer and adjacent to the resin substrate. An optical film, which is used in an image display device and is foldable, and is provided with: a resin substrate, which is selected from the group consisting of polyimide resin, polyimide resin, polyimide resin and Consisting of one or more resins in the group consisting of polyester resins; a functional layer provided on the first surface side of the resin substrate; a first optical adjustment layer provided on the resin substrate and the function Between the layers and adjacent to the above-mentioned functional layer; and a third optical adjustment layer provided on the second surface of the above-mentioned resin substrate which is opposite to the above-mentioned first surface. The optical film according to claim 1 or 3, wherein the refractive index of the first optical adjustment layer is lower than the refractive index of the resin substrate and higher than the refractive index of the functional layer. The optical film according to claim 1 or 3, 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 or 3, 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 6, 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 or 3, wherein the yellow index of the optical film is 15 or less. The optical film according to claim 1 or 3, wherein the optical film is folded so that the functional layer becomes the inner side and the distance between the opposing sides of the optical film becomes 10 mm after the repetition is performed 10,000 times No cracks or breaks occurred during the 180° test. The optical film according to claim 1 or 3, wherein the optical film is folded in such a manner that the functional layer becomes the outer side and the distance between the opposing sides of the optical film becomes 30 mm after the repetition is performed 10,000 times No cracks or breaks occurred during the 180° test. An optical film, which is used in an image display device and is foldable, and includes: a light-transmitting substrate; a first antistatic layer disposed on the first side of the light-transmitting substrate; and a second antistatic layer The electrostatic layer is provided on the second surface side of the translucent base material that is opposite to the first surface. The optical film according to claim 11, wherein the yellow index of the optical film is 15 or less. The optical film according to claim 11, wherein the first antistatic layer is an antistatic hard coat layer. The optical film according to claim 11, further comprising an optical adjustment layer provided on the side opposite to the translucent substrate side of the first antistatic layer. The optical film according to claim 11, further comprising a hard coat layer provided between the light-transmitting substrate and the first antistatic layer. The optical film according to claim 11, wherein the saturation band of the front surface of the optical film when a voltage of 10kV is applied from the front surface of the optical film at a distance of 50 mm from the front surface of the optical film under an environment of 23°C and 50% relative humidity The absolute value of the voltage exceeds 0kV. The optical film according to claim 11, wherein, in the above-mentioned optical film, the test is not performed when the test of 180° is folded so that the distance between the opposite sides of the above-mentioned optical film becomes 3mm after repeated 100,000 times. Cracks or breaks occur. The optical film according to claim 11, wherein the light-transmitting substrate is a substrate composed of a polyimide-based resin, a polyamide-based resin, or a mixture of these. A foldable image display device comprising: a display element; and the optical film according to claim 1, 3 or 11, which is arranged on the side of the observer more than the display element. The image display device according to claim 19, wherein the display element is an organic light emitting diode element.

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