Optical film and image display device

Abstract

To provide an optical film which has excellent impact resistance and is foldable, and an image display device having the same.SOLUTION: A light-transmissive optical film 10 which is used in an image display device and is foldable includes a resin substrate 11, a hard coat layer 12 provided on a first surface 11A side of the resin substrate 11, and a resin layer 13 which is provided on a second surface 11B side opposite to the first surface 11A of the resin substrate 11 and has film thickness of 50 μm or more and 300 μm or less, wherein a shear storage elastic modulus G' at 25°C in a frequency range of 500 Hz or more and 1,000 Hz or less in the optical film 10 exceeds 200 MPa and 1,200 MPa or less, and a shear loss elastic modulus G'' at 25°C in a frequency range of 500 Hz or more and 1,000 Hz or less in the optical film is 3 MPa or more and 150 MPa or less.SELECTED DRAWING: Figure 1

Description

REFERENCE TO RELATED APPLICATIONS

[0001] This application is a direct sequel to the Japanese application No. 2017-1447 (filed on January 1, 2017) No. 6,313,523, the entire disclosure of which is incorporated herein by reference. It is considered part of the specification. [Technical field]

[0002] The present invention relates to an optical film and an image display device. [Background technology]

[0003] Image display devices such as smartphones and tablet terminals have been known for some time. In recent years, foldable image display devices have been developed. However, if a cover glass is used for an image display device, Although it has excellent hardness, there is a high risk of it breaking when you try to fold it. For image display devices that can be used with this method, an optical film made of resin is used instead of a cover glass. It has been investigated (for example, see JP 2016-125063 A). Summary of the Invention [Problem to be solved by the invention]

[0004] The optical film used in such a foldable image display device includes an optical film Since the surface of the optical filter may be subjected to impact, impact resistance is required. When the surface of the optical film is subjected to an impact, the surface of the optical film may be dented and the image display may be damaged. In a display device, a display panel (e.g., an organic light-emitting diode) that is located inside the optical film Components such as the panel may be damaged.

[0005] Regarding the dents on the surface of the optical film, there are two types: dents caused by the optical film itself and dents caused by the optical film itself. The dents are caused by the adhesive layer placed inside the image display device rather than the film. "Dent caused by the film itself" refers to a dent that occurs when an impact is applied to the surface of the optical film. This refers to a depression caused by deformation of the optical film itself, and is called "depression caused by the adhesive layer." "Dent" refers to the adhesive layer being soft, and when an impact is applied to the surface of the optical film, the optical The adhesive layer placed inside the image display device rather than the film undergoes plastic deformation, causing the optical filter to break. This refers to a depression that occurs when the rubber follows the plastic deformation of the adhesive layer.

[0006] For this reason, when an impact is applied to the surface of the optical film, the optical The dents caused by the optical film itself and the adhesive layer are suppressed, and the optical film The system requires excellent impact resistance so that the components inside the image display device are not damaged. However, no optical film with such excellent impact resistance has yet been obtained. This is the current situation.

[0007] The present invention has been made to solve the above problems. The present invention aims to provide a foldable optical film having the above-mentioned structure, and an image display device including the same. Let us assume that. [Means for solving the problem]

[0008] The present inventors have conducted extensive research into the above-mentioned problem, and have found that a resin substrate is provided with a halogen-free polymer film on one side thereof. In an optical film having a structure including a hard coat layer and a resin layer on the other side thereof, Film thickness is 50μm to 300μm, and the temperature is 25℃, 500Hz or higher for optical film. The shear storage modulus G' and shear loss modulus G'' in the frequency range below 1000 Hz are It has been found that excellent impact resistance can be obtained by setting each of these within a specific range. It was completed based on such knowledge.

[0009] According to one aspect of the present invention, a foldable light-transmitting optical device for use in an image display device is provided. A film comprising a resin substrate and a hard coat layer provided on a first surface side of the resin substrate. and a film thickness of 50 μm or less provided on a second surface side opposite to the first surface of the resin base material. and a resin layer having a thickness of 300 μm or less. The shear storage modulus G' in the frequency range of 1000 Hz or less is more than 200 MPa and less than 1200 MPa or less, and the optical film has a temperature of 25° C. and a frequency of 500 Hz or more and 1000 Hz or less. The shear loss modulus G´´ in the frequency range of 3 MPa to 150 MPa. Films will be provided.

[0010] In the above optical film, the distance between the opposing sides of the optical film is 30 mm. The optical film was folded 180 degrees 100,000 times without cracking. It is preferable that no cracks or breaks occur.

[0011] In the above optical film, the resin substrate is a polyimide resin, a polyamide resin, or The substrate may be a mixture of these materials.

[0012] According to another aspect of the present invention, there is provided a foldable image display device, comprising: a display panel; the optical film disposed on a viewer side of the display panel, the hard coat layer of the film is located closer to the viewer than the resin substrate. Placement is provided.

[0013] In the image display device, an adhesive layer is disposed between the optical film and the display panel. The adhesive layer may further be provided.

[0014] In the above image display device, the display panel may be an organic light-emitting diode panel. good. Effect of the Invention

[0015] According to one aspect of the present invention, a foldable optical film having excellent impact resistance is provided. According to another aspect of the present invention, an image display device including such an optical film can be provided. The device can be provided. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram of an optical film according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a solid shearing jig used for measuring the shear storage modulus G' and the shear loss modulus G''. [Diagram 3] 3(A) to 3(C) are schematic diagrams showing the state of the continuous folding test. [Figure 4] 4(A) and 4(B) are schematic diagrams showing the state of the folding static test. [Diagram 5] FIG. 5 is a schematic diagram of another optical film according to an embodiment of the present invention. [Figure 6] 1 is a schematic configuration diagram of an image display device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the optical film and the image display device according to the embodiments of the present invention will be described with reference to the drawings. In this specification, the terms "film" and "sheet" are used interchangeably. Thus, for example, "film The term "sheet" is used to include members such as sheets. Fig. 2 shows the schematic structure of the optical film. The shear storage modulus G´ and the shear loss modulus G´ Fig. 3 shows the schematic diagram of the solid shearing jig used to measure the shear strength of the solid. FIG. 4 is a schematic diagram showing a folding static test. FIG. 5 is a schematic diagram of another optical film according to this embodiment.

[0018] <<<Optical films>>> The optical film 10 shown in FIG. 1 is used in an image display device and is foldable. In this specification, the term "light-transmitting" refers to a material that is capable of transmitting light. For example, the total light transmittance is 50% or more, preferably 70% or more. , more preferably 80% or more, and particularly preferably 90% or more. It is not necessary that the transparent member is transparent, but may be semi-transparent.

[0019] The optical film 10 includes a resin substrate 11 and a The hard coat layer 12 and the second surface 11A of the resin substrate 11 are opposite to each other. 1B side and a resin layer 13 provided thereon. A release film may be provided on the surface opposite to the surface on the side of the material 11. The physical properties of the optical film 10 described in the fine print are those of the optical film 10 without a release film. The release film is peeled off when the product is used. does not constitute a part of the optical film.

[0020] In FIG. 1, the surface 10A of the optical film 10 is the surface 12A of the hard coat layer 12. In this specification, the surface of the optical film is defined as one side of the optical film. Since it is used to mean the surface, the surface opposite to the surface of the optical film is the optical film. The rear surface 10B of the optical film 10 is referred to as the rear surface in order to distinguish it from the front surface of the film. , which is a surface 13A of the resin layer 13 opposite to the surface on the resin base material 11 side.

[0021] For optical film 10, at 25°C, in the frequency range of 500 Hz to 1000 Hz The shear storage modulus G' of the filler is greater than 200 MPa and less than 1200 MPa. When the shear storage modulus G' of the film exceeds 200 MPa, the surface of the optical film is subjected to an impact. When the optical film is exposed to the light, not only the optical film itself is deformed, but also the inside of the image display device is deformed. Even if an adhesive layer is disposed, plastic deformation of the adhesive layer can be suppressed. When the shear storage modulus G' of the optical film is 1200 MPa or less, the optical property of the film when folded is The lower limit of the shear storage modulus G' of the optical film 10 is 40 It is preferable that the pressure is 0 MPa or more, and more preferable that the pressure is 500 MPa or more. By setting the lower limit in this range, better impact resistance can be obtained. The upper limit of the shear storage modulus G' of the film 10 is preferably less than 800 MPa. By setting the upper limit in this way, it is possible to obtain good restoring properties when the sheet is folded, left to stand, and then opened again. can be obtained.

[0022] For optical film 10, at 25°C, in the frequency range of 500 Hz to 1000 Hz The shear loss modulus G´´ of the optical film is 3 MPa or more and 150 MPa or less. If the shear loss modulus G´´ is less than 3 MPa, the impact absorption performance may decrease. In addition, when the shear loss modulus G'' of the optical film exceeds 150MPa, the hardness of the resin layer The lower limit of the shear loss modulus G'' of the optical film 10 is 20 MPa or more, and the shear loss modulus G'' of the optical film 10 is preferably From the viewpoint of making the optical film 10 thinner, the upper limit of the It is preferable that the pressure is 100 MPa or less, and more preferable that the pressure is 100 MPa or less.

[0023] The shear storage modulus G´ and shear loss modulus G´ were measured using a dynamic mechanical analyzer (DMA). The dynamic mechanical properties of the optical film 1 can be measured by a dynamic mechanical analyzer (DMA). When measuring the shear storage modulus G' and shear loss modulus G'' at 0, first, the optical filter is A sample is obtained by punching out a rectangular shape of 10 mm x 5 mm from the film 10. Two samples were prepared and measured using a dynamic viscoelasticity measuring device (product name: Rheogel-E4000, UBM Corporation). The specimen is attached to a solid shearing jig, which is an option for the FT-1000 (manufactured by FT-1000). Specifically, as shown in Figure 2, The solid shearing jig 20 is composed of a solid shear plate 21 (middle plate) made of metal and having a thickness of 1 mm. The solid shear plate 21 is provided with two L-shaped brackets 22 (outer plates) arranged on both sides thereof. One sample S is sandwiched between the plate 21 and one L-shaped metal fitting 22, and the solid shear plate 21 and the other The other sample S is sandwiched between the L-shaped metal fittings 22. In this case, the resin layer is on the solid shear plate 21 side. The sample S is sandwiched between the L-shaped metal fitting 22 and the hard coat layer of the sample S. Then, the screw 23 is inserted. Then, the sample S is fixed in place using a dynamic viscoelasticity measuring device (product name: Rheogel-E4000 (manufactured by UBM Co., Ltd.) from the upper and lower chucks After mounting the tensile test chucks, a solid shear was placed between the upper and lower chucks. The jig is attached with a chuck distance of 20 mm. The chuck distance is the upper chuck and the lower chuck. The distance between the chucks is the set temperature of 25°C and the temperature is increased at a rate of 2°C / min. In this state, the solid shear plate is fixed and the two L-shaped metal fittings are subjected to a strain of 1% and a frequency of 500H. Dynamic viscoelasticity measurement of solids at 25°C while applying vertical vibration in the range from z to 1000Hz and measuring the shear storage modulus G' and the shear loss modulus G'' of the optical film 10. Here, the shear storage in the optical film in the frequency range of 500 Hz to 1000 Hz is The storage modulus G´ and shear loss modulus G´´ are measured at frequencies of 500Hz and 750Hz on an L-shaped metal fitting. , 950 Hz, respectively, to determine the shear stress of the optical film at each frequency. The storage modulus G' and the shear loss modulus G'' were measured, and these shear storage modulus G' and The arithmetic mean value of the shear loss modulus G'' was calculated, and this measurement was repeated three times. The three arithmetic mean values ​​obtained are then further averaged to obtain the arithmetic mean value. The frequency range is 0 Hz to 1000 Hz because the frequencies in this range are within the range of a few centimeters. When an object is allowed to fall freely from a height, the surface of the optical film is damaged by a few microns to a few tens of microns. The frequency is the frequency at which the optical film deforms, and the display panel inside the image display device is This is because the frequency can cause damage to devices such as batteries.

[0024] Another film such as a polarizing plate is provided on one side of the optical film 10 via an adhesive layer or bonding layer. If the film is attached to the adhesive layer, peel off the other film together with the adhesive layer before storing it under shear. The elastic modulus G' and shear loss modulus G'' shall be measured. The peeling of other films shall be For example, the method can be carried out as follows. First, a pressure-sensitive adhesive layer or a bonding layer is provided on the optical film. The laminate with the other film attached is heated with a dryer to separate the optical film and the other film. Insert the tip of the cutter into the area that seems to be the interface between the two and slowly peel it off. By repeatedly heating and peeling, the adhesive layer, the bonding layer and other films can be peeled off. Even if such a peeling process is performed, the shear storage modulus G' and the shear loss There is no significant effect on the elastic modulus G´´ results.

[0025] The optical film 10 is foldable. Specifically, the optical film 10 has In contrast, the folding test (continuous folding test) described below was repeated 100,000 times. Even if the optical film is folded, it is preferable that the optical film does not crack or break. Even after repeated 200,000 times, the optical film 10 does not crack or break. It is more preferable that the optical film does not crack even after 1 million repeated cycles. It is more preferable that no breakage or rupture occurs. If cracks or the like occur in the optical film 10 after 100,000 repeated cycles, the optical film 1 The folding property of the hard coat layer 12 is insufficient. The optical film 10 may be folded in such a manner that the hard coat layer 12 is not exposed to the outside. Alternatively, the optical film 10 may be folded so that the optical film 10 faces the optical axis. However, it is preferable that cracks or breaks do not occur in the optical film.

[0026] Another film such as a polarizing plate is provided on one side of the optical film 10 via an adhesive layer or bonding layer. If the adhesive layer is attached to the film, remove it together with the adhesive layer and other films in the same manner as above. After peeling the film, the continuous folding test shall be carried out. Even if there is any, it does not have a significant effect on the results of the continuous folding test.

[0027] The continuous folding test is carried out as follows. In the bending test, first, the side portion 10C of the optical film 10 and the side portion opposite to the side portion 10C are 10D are fixed by fixing parts 30 arranged in parallel. The optical film 10 in the continuous folding test is rectangular ( For example, a rectangle of 30 mm x 100 mm is preferable. Thus, the fixing portion 30 is slidable in the horizontal direction.

[0028] Next, as shown in FIG. 3B, the fixing parts 30 are moved closer to each other. Then, the optical film 10 is deformed so as to be folded, and then, as shown in FIG. The distance between the two opposing sides of the film 10 fixed by the fixing portion 30 is 30 mm. After the fixing part 30 is moved in the opposite direction, the deformation of the optical film 10 is prevented. Eliminate the problem.

[0029] As shown in FIG. 3(A) to (C), the optical film 10 is fixed by moving the fixing portion 30. The optical film 10 can be folded by 180°. When a continuous folding test is performed so that the bottom end does not protrude and the fixing part 30 is closest to the bottom end, By controlling the distance between the two opposing sides of the optical film 10 to 30 mm, In this case, the outer diameter of the bent portion 10E is regarded as 30 mm. The thickness of the mount 10 is sufficiently small compared to the interval (30 mm) between the fixing parts 30. The results of the continuous folding test of the optical film 10 show that the influence of the thickness of the optical film 10 is small. In the optical film 10, the The test was repeated 100,000 times to fold the product 180 degrees so that the distance between the opposing sides was 30 mm. It is preferable that the optical film 10 does not crack or break when the adhesive is applied. A continuous folding test was conducted 100,000 times by folding the material 180 degrees so that the gap between the parts was 6 mm. It is more preferable that the optical film 10 does not crack or break when the optical film 10 is heated. Repeated 100,000 times folding tests were conducted in which the edge spacing was 3 mm and the product was folded 180 degrees. It is more preferable that the optical film 10 is not cracked or broken when the heat treatment is performed. The test was repeated 100,000 times, folding the product 180 degrees so that the gap between the edges was 2 mm. Most preferably, it will not crack or break when turned over.

[0030] In the optical film 10, as shown in FIG. 4(A), The side portion 10C and the side portion 10D facing the side portion 10C are spaced apart from each other by a distance of 30 mm. The optical film 10 is fixed to the fixing parts 35 arranged in parallel so that the distance between the fixing parts 35 is 1 mm. A folding test was carried out in which the product was left to stand at 70°C for 240 hours in a folded state. As shown in the figure, by removing the fixing portion 35 from the side portion 10D after the folding static test, The folded state was released, and the optical film 10 was left at room temperature for 30 minutes. When the opening angle θ, which is the angle at which the optical film 10 naturally opens, is measured, the opening angle θ of the optical film 10 is 10 It is preferable that the opening angle θ is 0° or more. Note that the larger the opening angle θ, the better the restorability. The folding test is performed with the hard coat layer 12 facing inward. The optical film 10 may be folded so that the hard coat layer 12 is Alternatively, the optical film 10 may be folded so that the optical film 10 faces outward. At most, it is preferable that the opening angle θ be 100° or more.

[0031] The surface 10A of the optical film 10 (the surface 12A of the hard coat layer 12) is JIS K5 Hardness measured by the pencil hardness test specified in 600-5-4:1999 (pencil hardness ) is preferably B or higher, more preferably H or higher. The strength test was performed with a pencil moving at a speed of 1 mm / sec with a load of 1 kg. The pencil hardness test is carried out in a pencil hardness state where the surface of the optical film is not scratched. The hardness of the pencil is the highest hardness not found. When measuring pencil hardness, several pencils with different hardnesses are used. The pencil hardness test is carried out five times for each pencil, and the optical filter is tested four or more times out of five. If the surface of the film is not scratched, the surface of the optical film is scratched with a pencil of this hardness. The above scratches were not observed on the surface of the optical film subjected to the pencil hardness test. This refers to what can be seen when observed through a fluorescent lamp.

[0032] The optical film 10 preferably has a yellow index (YI) of 15 or less. When the YI of the optical film 10 exceeds 15, the yellowish tinge of the optical film becomes noticeable and the transparency is reduced. The Yellow Index (YI) is a spectral index that indicates the degree of yellowness of a color. UV meter (product name: UV-3100PC, manufactured by Shimadzu Corporation, light source: tungsten lamp) The yellow ink of the optical film 10 was measured using a deuterium lamp. The upper limit of the index (YI) is more preferably 10 or less.

[0033] In addition, another film such as a polarizing plate is attached to one side of the optical film 10 via an adhesive layer or a bonding layer. If a film is provided, the adhesive layer and other layers are also attached in the same manner as above. After peeling off the film, the yellow index (YI) is measured. However, even if such a peeling process is performed, it has no significant effect on the measurement of the yellow index (YI). There is no significant impact.

[0034] In order to adjust the yellow index (YI) of the optical film 10, for example, The material 11 and the resin layer 13 may contain a blue pigment, which is the complementary color of yellow. Even if the yellowing caused by using a polyimide substrate is a problem, By incorporating a blue pigment into the resin substrate 11 or the resin layer 13, the yellow ink of the optical film can be obtained. It can lower Dex (YI).

[0035] The blue coloring matter may be either a pigment or a dye. For example, an optical filter may be used. When the film 10 is used in an organic light-emitting diode display device, it is necessary to use a film having both light resistance and heat resistance. As the blue coloring matter, polycyclic organic pigments and metal complex organic pigments are preferably used as dyes. Compared to molecular dispersion, the degree of molecular cleavage caused by ultraviolet rays is less and the light resistance is significantly superior, so it is It is preferable for applications requiring light resistance, and more specifically, phthalocyanine organic pigments are preferable. However, since the pigment is dispersed in the solvent, the transparency may be affected by particle scattering. Since there is a possibility of photoinduced retardation, it is preferable to set the particle size of the pigment dispersion within the Rayleigh scattering region. On the other hand, when the transparency of the optical film is important, the blue dye should be resistant to solvents. It is preferable to use a dye that undergoes molecular dispersion.

[0036] The optical film 10 preferably has a transmittance of 8% or less for light having a wavelength of 380 nm. If the transmittance of the optical film exceeds 8%, when the optical film is used in a mobile device, The polarizer may be easily deteriorated by exposure to ultraviolet light. (Product name: UV-3100PC, manufactured by Shimadzu Corporation, light source: tungsten lamp and The transmittance can be measured using a 3-phase IR (3000 Hz) and a deuterium lamp. The upper limit of the transmittance of the optical film 10 is preferably 5%. The transmittance of the optical film 10 is preferably determined based on the ultraviolet absorption in the resin layer 13, which will be described later. This can be achieved by adjusting the amount of the agent added, for example.

[0037] The haze value (total haze value) of the optical film 10 is preferably 2.5% or less. When the haze value of an optical film exceeds 2.5%, it is considered that the optical film is not suitable for use in a mobile device. In this case, the image display surface may become white. The above haze value must be 1.5% or less. It is more preferable that the content is 1.0% or less.

[0038] The above haze values ​​were measured using a haze meter (product name "HM-150", manufactured by Murakami Color Research Laboratory). It can be measured by a method conforming to JIS K7136:2000 using the above. The haze value was measured after cutting into a piece of 50 mm x 100 mm without curling or wrinkles. Place the optical film so that the front side of the film faces away from the light source in a state free of fingerprints and dust. The film is measured three times, and the arithmetic mean value of the three measurements is used. "Measure three times" does not mean measuring the same place three times, but measuring three different places. In the optical film 10, the surface 10A seen by the naked eye is flat. The resin layer 12 is also flat, and the variation in the film thickness is within the range of ±10%. Therefore, by measuring the haze value at three different points on the cut optical film, It is believed that the average haze value of the entire surface of the optical film can be obtained. The variation in values ​​was small even when the measurement target was as long as 1m x 3000m, using a 5-inch smartphone. Even if the size is about the same as that of a smartphone, the error is within ±10%. If it is not possible to cut it out, for example, the entrance opening of the HM-150 is 20 mmφ when measuring. Therefore, a sample size of 21 mm or more in diameter is required. The optical film may be cut to a size of 22 mm x 22 mm or more. If the distance is small, move it little by little or change the angle as long as the light spot does not shift. Thus, there are three measurement points.

[0039] In addition, another film such as a polarizing plate is attached to one side of the optical film 10 via an adhesive layer or a bonding layer. If a film is provided, the adhesive layer and other layers are also attached in the same manner as above. After removing the film, thoroughly wipe off any dirt on the adhesive layer or the bonding layer with alcohol. The haze value is measured from the peeling step. There is no significant effect on the measurement of values.

[0040] In recent years, the backlight of image display devices such as personal computers and tablet terminals has become Light emitting diodes (LEDs) are actively used as a light source. However, this light-emitting diode emits a strong light called blue light. Blue light has a wavelength of 380 to 495 nm and is similar to ultraviolet light, making it a strong Because it has high energy, it can reach the retina without being absorbed by the cornea or lens, and it It is said that this can cause damage to the eyes, eye fatigue, and adverse effects on sleep. When this system is applied to an image display device, it is possible to obtain a blue-ray image without affecting the color of the display screen. It is preferable that the light shielding property is excellent. From this viewpoint, the optical film 10 has a spectral transmittance of less than 1% at a wavelength of 380 nm. The spectral transmittance at a wavelength of 410 nm is less than 10%, and the spectral transmittance at a wavelength of 440 nm is It is preferable that the spectral transmittance at a wavelength of 380 nm is 1% or less. If the spectral transmittance at a wavelength of 410 nm is 10% or more, The problem of light cannot be solved, and the spectral transmittance at a wavelength of 440 nm is 7 If it is less than 0%, it will affect the color of the display screen of the image display device using the optical film. The optical film 10 has a wavelength of 100 nm, which is the wavelength of blue light. While it sufficiently absorbs light in the wavelength range below 410 nm, it also fully absorbs light with wavelengths above 440 nm. It allows a certain amount of blue light to pass through, and has excellent blue light blocking properties without affecting the color of the display screen. In addition, the optical film 1 having such excellent blue light shielding properties can be obtained. When the organic light-emitting diode (OLED) display device is applied to the image display device, the organic It is also effective in suppressing the deterioration of light-emitting diode elements.

[0041] The optical transmittance of the optical film 10 is almost 0% up to a wavelength of 380 nm. The light transmission gradually increases from 400 nm, and the light transmission increases sharply at a wavelength of 440 nm. Specifically, for example, the wavelength is preferably between 410 nm and 440 nm. It is preferable that the light transmittance changes in a sigmoid curve. The spectral transmittance at m is more preferably less than 0.5%, and even more preferably less than 0.2%. The spectral transmittance at a wavelength of 410 nm is preferably less than 7%, more preferably less than 5%. %, and the spectral transmittance at a wavelength of 440 nm is more preferably 75% or more, and even more preferably The optical film 10 has a spectral transmittance of 80% or more at a wavelength of 420 nm. It is preferable that the spectral transmittance is less than 50%. The optical film 10 exhibits a sharp increase in transmittance at a wavelength of about 440 nm. It is possible to obtain extremely excellent blue light blocking properties without affecting the color tone of the surface.

[0042] The optical film 10 has a spectral transmittance of less than 0.1% at a wavelength of 380 nm. More preferably, the spectral transmittance at a wavelength of 410 nm is less than 7%. It is preferable that the spectral transmittance at a wavelength of 440 nm is 80% or more.

[0043] The optical film 10 has a transmittance in the wavelength range of 415 to 435 nm obtained by using the least squares method. It is preferable that the slope a of the overspectrum is a>2.0. In the blue light wavelength range, for example, the wavelength range of 415 to 435 nm, The blue light blocking effect may be weakened due to the lack of sufficient light blocking. It is possible that the light wavelength range (wavelength 415-435 nm) of the light is being cut too much. In this case, the backlight of the image display device or the emission wavelength region (for example, the wavelength 43 of OLED) 0 nm) and cause problems such as poor color reproduction. The above slope a can be measured in increments of 0.5% using a spectrometer ( Using a UVPC-2450 (manufactured by Shimadzu Corporation), a minimum of 5 points were measured within 1 nm. The transmittance data for each component can be calculated by measuring the transmittance between 415 and 435 nm. .

[0044] The optical film 10 preferably has a blue light blocking rate of 40% or more. If the blue light blocking rate is less than 40%, the problems caused by blue light mentioned above will not be fully resolved. The above blue light blocking rate is, for example, JIS T7333: This is a value calculated by the 2005 standard. Note that such a blue light blocking rate is calculated, for example, as follows: This is achieved by the resin layer 13 containing a sesamol-type benzotriazole monomer, which will be described later. It is possible.

[0045] The use of the optical film 10 is not particularly limited, but examples of the use of the optical film 10 include: For example, smartphones, tablet devices, personal computers (PCs), wearables Image display devices such as mobile terminals, digital signage, televisions, and car navigation systems The optical film 10 is also suitable for use in vehicles. The form of the product is that it is used in applications that require flexibility, such as foldable and rollable. Also preferred.

[0046] The optical film 10 may be cut to a desired size, or may be in a roll. When the optical film 10 is cut to a desired size, the size of the optical film is not particularly limited and is appropriately determined depending on the size of the display surface of the image display device. The size of the optical film 10 is, for example, 2.8 inches or more and 500 inches or less. In this specification, "inch" means that when the optical film has a rectangular shape, It means the length of the diagonal, in the case of a circle, it means the diameter, in the case of an ellipse, The average value of the sum of the minor axis and the major axis is used here. In this case, the aspect ratio of the optical film when calculating the above inches is the display screen of the image display device. There is no particular limitation as long as there is no problem. For example, vertical:horizontal=1:1, 4:3, 16:10, 16 However, especially for in-vehicle applications and digital signage, The aspect ratio of the optical film 10 is not limited to this. If the size is large, cut it out from any position to A5 size (148mm x 210mm). Then, cut out to the size of each measurement item.

[0047] The optical film 10 may be disposed inside the image display device. It is preferable that the surface of the image display device is used near the surface of the image display device. When used in a liquid crystal display, the optical film 10 acts as a cover film in place of a cover glass. It functions as such.

[0048] <<Resin substrate>> The resin substrate 11 is a substrate made of a resin having optical transparency. The thickness of the resin substrate 11 is It is preferable that the thickness of the resin substrate is 10 μm or more and 100 μm or less. If the content is less than 100%, the optical film may curl significantly and may have insufficient hardness. Furthermore, when optical films are manufactured using a roll-to-roll process, wrinkles tend to occur. On the other hand, if the thickness of the resin substrate exceeds 100 μm, The folding performance of the optical film becomes insufficient and cannot meet the requirements of the continuous folding test. In addition, the optical film becomes heavy, which is not preferable in terms of weight reduction. The cross section of the resin substrate was photographed using a scanning electron microscope (SEM) and the cross section was The thickness of the resin substrate is measured at 20 points, and the arithmetic average value of the thicknesses at the 20 points is used. The method for taking a cross-sectional photograph of the substrate is the same as that for taking a cross-sectional photograph of the hard coat layer. The lower limit of the thickness of the substrate 11 is more preferably 25 μm or more, and the upper limit of the thickness of the resin substrate 11 is preferably 80 μm or more. It is more preferable that the length is equal to or less than m.

[0049] The resin constituting the resin substrate 11 may be, for example, a polyimide resin or a polyamide-imide resin. resin, polyamide resin, polyester resin (e.g., polyethylene terephthalate resin and Polyethylene naphthalate resin, or a mixture of two or more of these resins. Among these, the material that is least likely to crack or break during the continuous folding test is It has excellent hardness and transparency, and is also excellent in heat resistance. From the viewpoint of being able to impart excellent hardness and transparency, polyimide resins and polyamide resins are preferred. fats, oils, or mixtures thereof are preferred.

[0050] Polyimide resins are obtained by reacting a tetracarboxylic acid component with a diamine component. The tetracarboxylic acid component and the diamine component are polymerized to obtain polyamic acid, and the imide The imidization may be carried out by thermal imidization or chemical imidization. It is also possible to produce the polyimide by a method that combines thermal imidization and chemical imidization. The imide resin may be an aliphatic polyimide resin, but may also be an aromatic resin containing an aromatic ring. The aromatic polyimide resin is preferably a polyimide resin. At least one of the moiety and the diamine component contains an aromatic ring.

[0051] As a specific example of the tetracarboxylic acid component, tetracarboxylic dianhydride is preferably used. , cyclohexanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride , dicyclohexane-3,4,3',4'-tetracarboxylic dianhydride, pyromellitic acid Dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'-Benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyl Tetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride , 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2 ,3-dicarboxyphenyl)propane dianhydride, Bis(3,4-dicarboxyphenyl)propane dianhydride ) ether dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 1,1 -Bis(2,3-dicarboxyphenyl)ethane dianhydride, Bis(2,3-dicarboxy phenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2 ,2-Bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoro Dipropane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3 ,3,3-Hexafluoropropane dianhydride, 1,3-bis[(3,4-dicarboxy) 1,4-Bis[(3,4-dicarboxy)benzoyl]benzene dianhydride Benzene dianhydride, 2,2-bis{4-[4-(1,2-dicarboxy)phenoxy]furan phenyl}propane dianhydride, 2,2-bis{4-[3-(1,2-dicarboxy)phenol 4-[4-(1,2-dicarboxy)phenyl]propane dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride 4,4'-bis[4-(1,2-dicarboxy)phenyl]ketone dianhydride 4,4'-bis[3-(1,2-dicarboxy)phenoxy]biphenyl dianhydride 〕Biphenyl dianhydride, Bis{4-〔4-(1,2-dicarboxy)phenoxy〕phenyl ketone dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl }ketone dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl} Sulfonic dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl} Sulfonic dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl} Sulfide dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl }Sulfide dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride 3,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3'-(hexafluoroisopropylidene)diphthalic anhydride (xafluoroisopropylidene)diphthalic anhydride, 2,3,6,7-naphthalenetetra Carboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,2, 5,6-Naphthalenetetracarboxylic dianhydride, 1,2,3,4-Benzenetetracarbo 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7 -Anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic These may be used alone or in combination of two or more. Cut.

[0052] Specific examples of the diamine component include p-phenylenediamine, m-phenylenediamine, o-Phenylenediamine, 3,3'-diaminodiphenyl ether, 3,4'-diamino Diphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl Diphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl Diphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl Nilsulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone Non, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4 '-Diaminobenzanilide, 3,3'-diaminodiphenylmethane, 4,4'-diamino Nodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-di(3-aminophenyl)methane 2,2-di(4-aminophenyl)propane, 2-(3-aminophenyl)propane 2,2-di(3-aminophenyl)-1-(4-aminophenyl)propane ,1,1,3,3,3-Hexafluoropropane, 2,2-di(4-aminophenyl)- 1,1,1,3,3,3-Hexafluoropropane, 2-(3-aminophenyl)-2- (4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 1,1- Di(3-aminophenyl)-1-phenylethane, 1,1-di(4-aminophenyl)- 1-Phenylethane, 1-(3-aminophenyl)-1-(4-aminophenyl)-1- Phenylethane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4- 1,4-bis(3-aminophenoxy)benzene, 1,4 -Bis(4-aminophenoxy)benzene, 1,3-bis(3-aminobenzoyl)benzene 1,3-bis(4-aminobenzoyl)benzene, 1,4-bis(3-aminobenzoyl)benzene 1,4-bis(4-aminobenzoyl)benzene, 1,3-bis(3 -amino-α,α-dimethylbenzyl)benzene, 1,3-bis(4-amino-α,α- dimethylbenzyl)benzene, 1,4-bis(3-amino-α,α-dimethylbenzyl) Benzene, 1,4-bis(4-amino-α,α-dimethylbenzyl)benzene, 1,3- Bis(3-amino-α,α-ditrifluoromethylbenzyl)benzene, 1,3-bis( 4-Amino-α,α-ditrifluoromethylbenzyl)benzene, 1,4-bis(3-amino 1,4-bis(4-amino-α,α-ditrifluoromethylbenzyl)benzene α,α-ditrifluoromethylbenzyl)benzene, 2,6-bis(3-aminophenoxy) Benzonitrile, 2,6-bis(3-aminophenoxy)pyridine, N,N'-bis (4-aminophenyl)terephthalamide, 9,9-bis(4-aminophenyl)fluoro 2,2'-Dimethyl-4,4'-diaminobiphenyl, 2,2'-Ditrifluoro Methyl-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl phenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dimethyl- 4,4'-diaminobiphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-Bis(4-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[ 4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone, Bis[4-(4-aminophenoxy)phenyl]sulfone, Bis[4-(3-aminophenoxy)phenyl]sulfone bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether , 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4 -(4-aminophenoxy)phenyl]propane, 2,2-bis[3-(3-aminophen (oxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoro Propane, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,3 -Bis[4-(4-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(3 -aminophenoxy)benzoyl]benzene, 1,4-bis[4-(4-aminophenoxy)benzoyl]benzene 1,3-bis[4-(3-aminophenoxy)-α,α-dibenzoylbenzene methylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)-α,α-di methylbenzyl]benzene, 1,4-bis[4-(3-aminophenoxy)-α,α-di methylbenzyl]benzene, 1,4-bis[4-(4-aminophenoxy)-α,α-di methylbenzyl]benzene, 4,4'-bis[4-(4-aminophenoxy)benzoyl ]diphenyl ether, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl )phenoxy]benzophenone, 4,4'-bis[4-(4-amino-α,α-dimethyl benzyl)phenoxy]diphenyl sulfone, 4,4'-bis[4-(4-aminophen 3,3'-diamino-4,4'-diphenoxy]diphenyl sulfone Benzophenone, 3,3'-diamino-4,4'-diphenylphenoxybenzophenone, 3, 3'-Diamino-4-phenoxybenzophenone, 3,3'-diamino-4-biphenoxy Dibenzophenone, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetrabenzophenone tetramethyl-1,1'-spirobiindan, 6,6'-bis(4-aminophenoxy)- 3,3,3',3'-Tetramethyl-1,1'-spirobiindane, 1,3-bis(3- Aminopropyl)tetramethyldisiloxane, 1,3-bis(4-aminobutyl)tetra Methyldisiloxane, α,ω-bis(3-aminopropyl)polydimethylsiloxane, α ,ω-bis(3-aminobutyl)polydimethylsiloxane, bis(aminomethyl)ether bis(2-aminoethyl) ether, bis(3-aminopropyl) ether, bis( 2-aminomethoxy)ethyl]ether, bis[2-(2-aminoethoxy)ethyl]ether ether, bis[2-(3-aminopropyl)ethyl]ether, trans-cyclohexane Sandiamine, trans-1,4-bismethylenecyclohexanediamine, 2,6-bi Bis(aminomethyl)bicyclo[2,2,1]heptane, 2,5-bis(aminomethyl)bicyclo[2,2,1]heptane Cyclo[2,2,1]heptane, and some or all of the hydrogen atoms on the aromatic ring of the above diamines All of the groups are fluoro, methyl, methoxy, trifluoromethyl, or trifluoro. Diamines substituted with substituents selected from methoxy groups can also be used. They may be used alone or in combination of two or more.

[0053] From the viewpoint of improving light transmittance and rigidity, the polyimide resin is preferably an aromatic polyimide. (i) a fluorine atom, (ii) an aliphatic ring, and (iii) an aromatic ring Polyimide-based compound containing at least one linking group selected from the group consisting of linking groups that break electronic conjugation The resin is preferably a polyimide resin containing at least one of (i) and (iii). Polyimide resins containing aromatic rings have high orientation and high rigidity. However, transmittance tends to decrease depending on the absorption wavelength of the aromatic ring. When the polyimide resin contains (i) fluorine atoms, it is difficult to transfer the electron state in the polyimide skeleton. In addition, the polyimide resin has (ii) a fatty acid In the case of a polyimide containing an aromatic ring, the conjugation of the π electrons in the polyimide skeleton is broken, and the charge in the skeleton is reduced. The light transmission is improved because the movement of the material can be inhibited. iii) In the case where a linking group that breaks the electronic conjugation between aromatic rings is contained, The point is that the charge transfer within the framework can be inhibited by breaking the conjugation of π electrons. The light transmittance is improved. Examples of the linking group that cuts the electronic conjugation between such aromatic rings include For example, ether bonds, thioether bonds, carbonyl bonds, thiocarbonyl bonds, amino The aryl, sulfonyl and sulfinyl bonds, as well as fluorine-substituted Examples of the linking group include a divalent linking group such as an alkylene group.

[0054] Among these, polyimide resins containing aromatic rings and fluorine atoms are preferred. is preferably used from the viewpoints of improving light transmittance and improving rigidity. The content of fluorine atoms in polyimide resins is measured by examining the surface of the polyimide resin with X-rays. The ratio (F / C) of the number of fluorine atoms (F) to the number of carbon atoms (C) measured by electron spectroscopy is It is preferably 0.01 or more, and more preferably 0.05 or more. If the fluorine atom content is too high, the inherent heat resistance of the polyimide resin may decrease. Therefore, the ratio (F / C) of the number of fluorine atoms (F) to the number of carbon atoms (C) is 1 or less. It is preferable that the ratio is 0.8 or less, and more preferably 0.8 or less. The above ratios measured by XPS were obtained using an X-ray photoelectron spectrometer (e.g., Thermo Sc The atomic percentage of each atom measured using the Theta Probe (Centific) It can be found from.

[0055] In addition, more than 70% of the hydrogen atoms bonded to carbon atoms in polyimide resins are aromatic. The polyimide resin, which is a hydrogen atom directly bonded to the aromatic ring, improves light transmittance, In addition, it is preferably used from the viewpoint of improving the rigidity. The ratio of hydrogen atoms directly bonded to aromatic rings to the total number of hydrogen atoms bonded to is More preferably, the content is 80% or more, and more preferably, 85% or more. More than 70% of the hydrogen atoms bonded to carbon atoms in the imide are directly bonded to aromatic rings. In the case of polyimide, which is a hydrogen atom, even after a heating process in the atmosphere, for example, 2 Even if stretching is performed at temperatures above 00°C, the optical properties, especially the total light transmittance and yellow index (Y The change in the amount of water bonded to the carbon atom contained in the polyimide resin is small. In the case of a polyimide in which 70% or more of the atomic atoms are hydrogen atoms directly bonded to an aromatic ring, It is assumed that the chemical structure of polyimide resin is unlikely to change due to its low reactivity with oxygen. The substrate made of polyimide resin has high heat resistance, and the processing step involving heating is easy. It is often used in devices that require this, but the carbon atoms contained in polyimide resins Polyimide system in which 70% or more of the hydrogen atoms bonded are hydrogen atoms directly bonded to aromatic rings If the material is a resin, these post-processing steps must be carried out in an inert atmosphere to maintain transparency. This has the advantage of reducing the cost of equipment and atmosphere control. Here, the number of hydrogen atoms bonded to carbon atoms contained in the polyimide resin is The ratio (number) of hydrogen atoms directly bonded to aromatic rings was measured by high-performance liquid chromatography of the decomposition product of polyimide. It can be determined using NMR, gas chromatography, mass spectrometry, and NMR. For example, the sample is decomposed with an alkaline aqueous solution or supercritical methanol, and the resulting The decomposition products were separated by high performance liquid chromatography, and the separated peaks were qualitatively analyzed. This was carried out using a gas chromatograph mass spectrometer and NMR, etc., and a high-performance liquid chromatograph The amount of hydrogen atoms in the aromatic rings of the polyimide was determined by using the The percentage of directly bonded hydrogen atoms (number) can be calculated.

[0056] In order to improve light transmittance and rigidity, the polyimide resin may be: Among them, the compound is preferably selected from the group consisting of structures represented by the following general formula (1) and the following general formula (3). It is preferable that the compound has at least one structure.

[0057] [ka]

[0058] In the above general formula (1), R 1 is a tetravalent group which is a tetracarboxylic acid residue, R 2 t trans-Cyclohexanediamine residue, trans-1,4-bismethylenecyclohexane Sandiamine residue, 4,4'-diaminodiphenyl sulfone residue, 3,4'-diaminodiphenyl A divalent group selected from the group consisting of a phenylsulfone residue and a divalent group represented by the following general formula (2): n represents the number of repeating units and is 1 or more. In the details, "tetracarboxylic acid residue" means a residue obtained by isolating four carboxylates from a tetracarboxylic acid. This refers to the residue obtained by removing the silyl group, and is the residue obtained by removing the acid dianhydride structure from a tetracarboxylic dianhydride. The term "diamine residue" refers to a diamine with two amino groups removed. This refers to a residue.

[0059] [ka] In the above general formula (2), R 3 and R 4 each independently represents a hydrogen atom, an alkyl group, or a perfluoroalkyl group.

[0060] [ka]

[0061] In the above general formula (3), R 5 is the residue of cyclohexanetetracarboxylic acid, Tantalumtetracarboxylic acid residue, dicyclohexane-3,4,3',4'-tetracarboxylic acid residues, and 4,4'-(hexafluoroisopropylidene)diphthalic acid residues At least one tetravalent group selected from R 6 represents a divalent group which is a diamine residue. n' represents the number of repeating units and is 1 or more.

[0062] In the above general formula (1), R 1 is a tetracarboxylic acid residue, as exemplified above. The above-mentioned tetracarboxylic dianhydride can be a residue obtained by removing the acid dianhydride structure from the above-mentioned tetracarboxylic dianhydride. R in general formula (1) 1 Among other things, the objective is to improve light transmittance and rigidity. From 4,4'-(hexafluoroisopropylidene)diphthalic acid residue, 3,3',4, 4'-biphenyltetracarboxylic acid residue, pyromellitic acid residue, 2,3',3,4'-biphenyltetracarboxylic acid residue Phenyltetracarboxylic acid residue, 3,3',4,4'-benzophenonetetracarboxylic acid Residue, 3,3',4,4'-diphenylsulfonetetracarboxylic acid residue, 4,4'-oxy Diphthalic acid residue, cyclohexanetetracarboxylic acid residue, and cyclopentanetetracarboxylic acid residue It is preferable that the carboxylic acid residue contains at least one selected from the group consisting of carboxylic acid residues, and further contains 4,4'-(Hexafluoroisopropylidene)diphthalic acid residue, 4,4'-oxydiphthalic acid residue from tetracarboxylic acid residues and 3,3',4,4'-diphenylsulfonetetracarboxylic acid residues It is preferable that the compound contains at least one selected from the group consisting of:

[0063] R 1 In the above, it is preferable that the total amount of these suitable residues is 50 mol % or more, and It is preferable that the content is 70 mol % or more, and more preferably 90 mol % or more.

[0064] Also, R 1 3,3',4,4'-biphenyltetracarboxylic acid residue, 3,3' , 4,4'-benzophenonetetracarboxylic acid residues, and pyromellitic acid residues. Tetracarboxylic acids suitable for improving stiffness, such as at least one selected from the group Group A and 4,4'-(hexafluoroisopropylidene)diphthalic acid residues group, 2,3',3,4'-biphenyltetracarboxylic acid residue, 3,3',4,4'-diphenyl Phenylsulfonetetracarboxylic acid residue, 4,4'-oxydiphthalic acid residue, cyclohexa cyclopentanetetracarboxylic acid residues, and cyclopentanetetracarboxylic acid residues. At least one of the tetracarboxylic acid residues suitable for improving transparency is selected from the group consisting of It is also preferable to use a mixture of these with group B).

[0065] In this case, the tetracarboxylic acid residue group (group A) suitable for improving the rigidity and The content ratio of the tetracarboxylic acid residue group (Group B) suitable for improving transparency is as follows: For every 1 mole of tetracarboxylic acid residue group (Group B) suitable for improving transparency, The tetracarboxylic acid residue group (group A) suitable for improving the rigidity is 0.05 mol or less. It is preferably from 0.1 to 5 mol, more preferably from 0.1 to 5 mol. The amount is preferably 0.3 mol or more and more preferably 4 mol or less.

[0066] R in the above general formula (1) 2 Among other things, the objective is to improve light transmittance and rigidity. From the viewpoint of a divalent group represented by the general formula (2) At least one divalent group is preferred, and further, 4,4'-diaminodiphenylsulfonyl is preferably used. sulfone residue, 3,4'-diaminodiphenylsulfone residue, and R 3 and R 4 but A divalent group represented by the above general formula (2), which is a perfluoroalkyl group, is selected from the group consisting of the divalent group represented by the above general formula (2). It is preferable that the aryl group is at least one divalent group.

[0067] R in the above general formula (3) 5 Among other things, the objective is to improve light transmittance and rigidity. From this viewpoint, 4,4'-(hexafluoroisopropylidene)diphthalic acid residue, 3,3' ,4,4'-diphenylsulfonetetracarboxylic acid residues, and oxydiphthalic acid residues. It is preferable to do so.

[0068] R5 In the above, it is preferable that the content of these suitable residues is 50 mol % or more, and more preferably 70 It is preferable that the content is 90 mol % or more, and more preferably 90 mol % or more.

[0069] R in the above general formula (3) 6 is a diamine residue, and the diamines exemplified above are The residue can be obtained by removing two amino groups from R in the above general formula (3). 6 and Among them, 2,2'-bis(trimethylsilyl)phenylene oxide is preferred from the viewpoint of improving light transmittance and rigidity. Fluoromethyl)benzidine residue, bis[4-(4-aminophenoxy)phenyl]sulf 4,4'-diaminodiphenylsulfone residue, 2,2-bis[4-(4-amino hexafluoropropane residue, bis[4-(3-aminophenoxy)phenyl]hexafluoropropane residue 4,4'-diamino-2,2'-bis(trifluoromethoxy)phenyl]sulfone residue ethyl)diphenyl ether residue, 1,4-bis[4-amino-2-(trifluoromethyl )phenoxy]benzene residue, 2,2-bis[4-(4-amino-2-trifluoromethyl 4,4'-diamino-2-(trifluorophenyl)hexafluoropropane residue, (trifluoromethyl)diphenyl ether residue, 4,4'-diaminobenzanilide residue, N,N'-bis(4-aminophenyl)terephthalamide residue, and 9,9-bis(4- At least one divalent group selected from the group consisting of aminophenyl)fluorene residues It is preferable that the aryl group contains 2,2'-bis(trifluoromethyl)benzidine residue, bis [4-(4-aminophenoxy)phenyl]sulfone residue, and 4,4'-diaminodiphenyl It is preferred that the alkyl group contains at least one divalent group selected from the group consisting of phenyl sulfone residues. It is.

[0070] R 6 In the above, it is preferable that the total amount of these suitable residues is 50 mol % or more, and It is preferable that the content is 70 mol % or more, and more preferably 90 mol % or more.

[0071] Also, R 6 As the bis[4-(4-aminophenoxy)phenyl]sulfone residue, 4 ,4'-Diaminobenzanilide residue, N,N'-bis(4-aminophenyl)terephthalic acid amide residue, paraphenylenediamine residue, metaphenylenediamine residue, and 4, At least one selected from the group consisting of 4'-diaminodiphenylmethane residues The diamine residue group (Group C) is suitable for improving rigidity, and the 2,2'-bis(trifluoromethyl) (fluoromethyl)benzidine residue, 4,4'-diaminodiphenylsulfone residue, 2,2- Bis[4-(4-aminophenoxy)phenyl]hexafluoropropane residue, bis[4 -(3-aminophenoxy)phenyl]sulfone 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 9,9-bis( At least one selected from the group consisting of 4-aminophenyl)fluorene residues It is also preferable to use it in combination with a diamine residue group (group D) suitable for improving transparency. I wish.

[0072] In this case, the diamine residue group (group C) suitable for improving the rigidity and the transparency The content ratio of the diamine residue group (group D) suitable for improving transparency is For 1 mole of the diamine residue group (group D) suitable for improving the rigidity, The amount of the diamine residue group (group C) is preferably 0.05 moles or more and 9 moles or less. The amount is preferably 0.1 mol or more and 5 mol or less, and more preferably 0.3 mol or more and 4 mol or less. It is more preferable to do so.

[0073] In the structures represented by the above general formula (1) and the above general formula (3), n and n' are Each independently represents the number of repeating units, which is 1 or more. The number n may be appropriately selected depending on the structure so as to exhibit a preferred glass transition temperature, which will be described later. The average number of repeating units is usually 10 to 2000, and more preferably 15 It is preferable that the ratio is 1 to 1000.

[0074] The polyimide resin may partially contain a polyamide structure. Examples of polyamide structures that may be used include tricarboxylic acids such as trimellitic anhydride. Polyamide-imide structures containing acid residues and polyamides containing dicarboxylic acid residues such as terephthalic acid are also available. An example of such a structure is a triamide structure.

[0075] From the viewpoint of heat resistance, it is preferable that the polyimide resin has a glass transition temperature of 250° C. or higher. On the other hand, it is preferable that the temperature is 270° C. or higher in view of ease of stretching and low bake temperature. From the viewpoint of reducing the amount of the resin, the glass transition temperature is preferably 400° C. or less, and more preferably 380° C. or less. It is preferable that:

[0076] Specifically, the polyimide resin may be, for example, a compound having a structure represented by the following formula: In the following formula, n is a repeating unit and represents an integer of 2 or more. [ka]

[0077] [ka]

[0078] [ka]

[0079] [ka]

[0080] [ka]

[0081] [ka]

[0082] [ka]

[0083] [ka]

[0084] [ka]

[0085] [ka]

[0086] [ka]

[0087] [ka]

[0088] [ka]

[0089] [ka]

[0090] [ka]

[0091] [ka]

[0092] [ka]

[0093] Polyamide resins include not only aliphatic polyamides but also aromatic polyamides (aramids). Polyamide resins are generally represented by the following formulas (21) and (22): The polyamide resin has a skeleton represented by the following formula (23): In the following formula, n is a repeating unit and is 2 or more. Represents an integer.

[0094] [ka]

[0095] [ka]

[0096] [ka]

[0097] Polyimide resins or polyamide resins represented by the above formulas (4) to (20) and (23) The substrate made of polyimide resin may be a commercially available one. Examples of such products include Neoprim manufactured by Mitsubishi Gas Chemical Co., Ltd., which is made of the above-mentioned aramid resin. An example of a commercially available product of the substrate made of such a material is Miktron manufactured by Toray Industries, Inc.

[0098] The polyimide resin or polyamide resin represented by the above formulas (4) to (20) and (23) is also The mide resin may be synthesized by a known method. For example, the mide resin represented by the above formula (4) may be used. The method for synthesizing the polyimide resin is described in JP 2009-132091 A. Specifically, 4,4'-hexafluoropropylidenebisphthalate represented by the following formula (24) is used. Acid dianhydride (FPA) and 2,2'-bis(trifluoromethyl)-4,4'-diaminobis It can be obtained by reacting with phenyl (TFDB). [ka]

[0099] The weight average molecular weight of the polyimide resin or polyamide resin is 3,000 or more and 500,000 or less. It is preferable that the range is 5,000 to 300,000, and more preferable that the range is 1 It is more preferable that the weight average molecular weight is in the range of 10,000 to 200,000. If the molecular weight exceeds 500,000, the viscosity increases and the solubility decreases. Therefore, it may not be possible to obtain a substrate having a smooth surface and a uniform film thickness. In the present specification, the "weight average molecular weight" is measured by gel permeation chromatography (GPC). This is a polystyrene equivalent value.

[0100] Among the above polyimide resins and polyamide resins, the polyamide resin having excellent transparency is Polyimide resin or aramid resin having a structure in which intramolecular or intermolecular charge transfer is unlikely to occur Specifically, fluorinated polyimide resins such as those represented by the above formulas (4) to (11) are preferred. Polyimide resins having an alicyclic structure such as the above formula (13) to (15), halides such as the above formula (23), Examples of suitable polyamide resins include polyamide resins having halogen groups.

[0101] In addition, in the fluorinated polyimide resins of the above formulas (4) to (11), etc., the fluorinated structure Since it has high heat resistance, it is not easily damaged by heat during the production of the polyimide resin base material. Since it is not colored by the solvent, it has excellent transparency.

[0102] From the viewpoint of being able to improve hardness, the resin base material 11 is preferably selected from the group consisting of the above formulas (4) to (11) and the like. or an aramide resin having a halogen group, such as the above formula (23) It is preferable to use a substrate made of a polyethylene resin. In particular, the hardness can be further improved. From the viewpoint of the above, it is preferable to use a substrate made of a polyimide resin represented by the above formula (4). preferable.

[0103] Examples of polyester resins include polyethylene terephthalate and polypropylene terephthalate. At least one of polybutylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate Examples of the resin include those containing seeds as constituent components.

[0104] <<Hard coat layer>> The hard coat layer 12 has a Martens hardness of 37 at the center of the cross section of the hard coat layer 12. In this specification, the term "Martens hardness" refers to a layer having a hardness of 5 MPa or more. Hardness measured by nanoindentation method when the indenter is pressed 500 nm The measurement of the Martens hardness by the nanoindentation method was carried out by HYSITRO This was done using the "TI950 TriboIndenter" manufactured by N (Hygitron). That is, under the following measurement conditions, the indenter is a Berkovich indenter (triangular The drill bit is pressed 500 nm into the center of the cross section of the hard coat layer and held there for a certain period of time to relieve residual stress. After the load is released, the maximum load after relaxation is measured, and the maximum load P max (μN) and Area A of a 500 nm deep depression (nm 2 ) and P max / A makes it hard like Martens The Martens hardness is calculated by taking the arithmetic average value of the values ​​obtained by measuring at 10 points. (Measurement conditions) ·Loading speed: 10nm / sec ·Holding time: 5 seconds ·Loading and unloading speed: 10nm / sec ·Measurement temperature: 25℃

[0105] The thickness of the hard coat layer 12 is preferably 1 μm or more and 20 μm or less. If the thickness of the hard coat layer 12 is less than 1 μm, the hardness of the hard coat layer may decrease. Furthermore, if the thickness exceeds 20 μm, the processability deteriorates due to the thickness being too large. In this specification, the "thickness of the hard coat layer" refers to the thickness of the hard coat layer. In the case of a hard coat layer structure, the thickness refers to the total thickness of each hard coat layer. The upper limit of the hard coat layer 12 is more preferably 15 μm or less, and 10 It is more preferable that the thickness is equal to or less than 1 μm.

[0106] The thickness of the hard coat layer was measured by cross-sectional observation of the hard coat layer using a scanning electron microscope (SEM). The cross-sectional image was photographed, and the thickness of the hard coat layer was measured at 20 points. The arithmetic average value of the film thickness at each point is used. The specific method for taking the cross-sectional photograph is described below. First, Optical film cut to 1 mm x 10 mm was embedded in embedding resin to create a block. Then, from this block, a uniform section with a thickness of 70 nm or less without holes was prepared using a general sectioning method. Sections of less than 100 nm in diameter were cut out. UC7" (Leica Microsystems, Inc.) or the like can be used. The remaining block from which uniform pieces without holes or other defects have been cut out is used as the measurement sample. Scanning electron microscope (SEM) (product name "S-4800", Hitachi High-Technologies Corporation) The cross-section of the measurement sample is photographed using the S-4800. When taking the photograph, the detector was set to "SE", the acceleration voltage to "5 kV", and the emission current to Set the current to "10μA" and observe the cross section. Adjust the focus and contrast to obtain the desired magnification. The brightness is adjusted appropriately from 100 to 100,000 times while observing whether each layer can be distinguished. When taking cross-sectional photographs using the S-4800, the aperture is set to " Set the monitor aperture to "3", the objective lens aperture to "3", and the WD to "8 mm". When measuring the thickness of the first layer, the thickness of the hard coat layer and the other layers may be measured during cross-sectional observation. It is important to be able to observe the interface contrast with the substrate (e.g., resin substrate) as clearly as possible. If the interface is difficult to see due to insufficient contrast, try using osmium tetroxide or tetraoxygen. The interface between the organic layers becomes easier to see when stained with ruthenium chloride or phosphotungstic acid. In addition, the contrast of the interface is easier to see at higher magnifications. In such cases, observations at low magnifications are also performed simultaneously. For example, 25,000x and 50,000x magnifications are used. Observe at two magnifications, high and low, such as 50,000 times, 50,000 times, and 100,000 times, and measure the arithmetic mean value at both magnifications. The average value is determined as the thickness of the hard coat layer.

[0107] The hard coat layer may have a single-layer structure, but from the viewpoint of improving folding performance, it is preferable to use a two-layer structure. The above multi-layer structure is preferable. In FIG. A coating layer 12B and a second hard coating layer 1 laminated on the first hard coating layer 12B. An example is shown in which the 2C is composed of

[0108] <First hard coat layer> The first hard coat layer 12B is a layer mainly for imparting hardness to the optical film. The first hard coat layer 12B has a martensite at the center of the cross section of the first hard coat layer 12B. The hardness of the material is preferably 500 MPa or more and 2000 MPa or less. If it is less than 2000 MPa, the hardness of the hard coat layer may be insufficient. If the first hard coat layer 12 is too thin, the folding performance of the optical film may become insufficient. The lower limit of the Martens hardness at the center of the cross section of B is preferably 600 MPa or more, The upper limit is preferably 1500 MPa or less.

[0109] The Martens hardness of the first hard coat layer 12B is 1 / 100 that of the second hard coat layer 12C. It is preferable that the Martens hardness is greater than the Martens hardness. Therefore, the optical film 10 has a particularly good pencil hardness. When a hardness test was conducted and a load was applied to the pencil to press the film, the deformation of the optical film 10 was suppressed. This is because the first hard coat layer 12B is made of maltene, which reduces scratches and dents. As a method for making the Martens hardness of the second hard coat layer 12C larger than the Martens hardness of the second hard coat layer 12C, For example, the content of inorganic particles described later is higher on the first hard coat layer 12B side. In addition, when the hard coat layer has a single layer structure, The hard coat layer is formed so that the inorganic particles are unevenly distributed on the substrate film side. The proportion of inorganic particles in the resin substrate is larger, and the proportion of inorganic particles in the resin substrate is smaller toward the surface of the optical film. Therefore, it is preferable that the slope be small.

[0110] The first hard coat layer 12B contains a resin. The first hard coat layer 12B is It is preferred that the resin further contains inorganic particles dispersed therein.

[0111] (resin) The resin contains a polymer (cured product) of a polymerizable compound (curable compound). It has at least one polymerizable functional group in the molecule. The polymerizable functional group is, for example, Examples of the unsaturated groups include ethylenically unsaturated groups such as (meth)acryloyl groups, vinyl groups, and allyl groups. In addition, "(meth)acryloyl group" refers to "acryloyl group" and "methacryloyl group". The term "group" includes both the above-mentioned and "groups".

[0112] As the polymerizable compound, a polyfunctional (meth)acrylate is preferable. Examples of acrylates include trimethylolpropane tri(meth)acrylate, Dipropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate acrylate, dipropylene glycol di(meth)acrylate, pentaerythritol triacrylate (Meth)acrylate, Pentaerythritol Tetra(Meth)acrylate, Dipentaerythritol Lithritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane triacrylate (Meth)acrylate, Ditrimethylolpropanetetra(meth)acrylate, Dipentaerythritol Tripentaerythritol penta(meth)acrylate, Tripentaerythritol octa(meth)acrylate ) acrylate, tetrapentaerythritol deca(meth)acrylate, isocyanuric Acid tri(meth)acrylate, isocyanuric acid di(meth)acrylate, polyester tri Poly(meth)acrylate, polyester di(meth)acrylate, bisphenol di(meth)acrylate tetra(meth)acrylate, diglycerol tetra(meth)acrylate, adamantyl di(meth)acrylate Acrylate, isobornyl di(meth)acrylate, dicyclopentane di(meth)acrylate acrylate, tricyclodecane di(meth)acrylate, ditrimethylolpropane tetra (Meth)acrylates and those modified with PO, EO, caprolactone, etc. can be done.

[0113] Among these, those having 3 to 6 functional groups are preferred since they can satisfactorily satisfy the above-mentioned Martens hardness. For example, pentaerythritol triacrylate (PETA), dipenta Erythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate Dipentaerythritol pentaacrylate (PETTA), Dipentaerythritol pentaacrylate (DPPA), Trimethicone Tyrolpropane tri(meth)acrylate, Tripentaerythritol octa(meth)acrylate acrylate, tetrapentaerythritol deca(meth)acrylate, etc. are preferred. In this specification, (meth)acrylate refers to acrylate and methacrylate. means.

[0114] In order to adjust the hardness and viscosity of the composition, improve adhesion, etc., a monofunctional (meth)acrylic acid may be further added. The monofunctional (meth)acrylate monomer may include a methacrylate monomer. For example, hydroxyethyl acrylate (HEA), glycidyl methacrylate, Polyethylene glycol (meth)acrylate, isostearyl (meth)acrylate , 2-Acryloyloxyethyl succinate, acryloylmorpholine, N-Acryloyl Triethyloxyethylhexahydrophthalimide, Cyclohexyl acrylate, Tetrahydantoyl Drofulyl acrylate, isobornyl acrylate, phenoxyethyl acrylate, and adamantyl acrylate.

[0115] The weight average molecular weight of the monomer is less than 1000 from the viewpoint of improving the hardness of the resin layer. The weight of the polymerizable oligomer is preferably from 200 to 800, and more preferably from 200 to 800. The average molecular weight is preferably 1,000 or more and 20,000 or less, and more preferably 1,000 or more and 10,000 or less. It is more preferable that the molecular weight is 2,000 or more and 7,000 or less, and further more preferable that the molecular weight is 2,000 or more and 7,000 or less.

[0116] (Inorganic particles) The inorganic particles are not particularly limited as long as they can improve the hardness. From the viewpoint of obtaining a high degree of adhesion, silica particles are preferred. Among silica particles, reactive silica particles are preferred. The reactive silica particles preferably form a crosslinked structure with the polyfunctional (meth)acrylate. The reactive silica particles can be used to form the first This can sufficiently increase the hardness of the hard coat layer 12B.

[0117] The reactive silica particles preferably have a reactive functional group on the surface thereof. As the functional group, for example, the above-mentioned polymerizable functional groups are preferably used.

[0118] The reactive silica particles are not particularly limited, and any conventionally known reactive silica particles may be used. For example, reactive silica particles described in JP-A-2008-165040 can be mentioned. In addition, examples of commercially available reactive silica particles include MIBK-S manufactured by Nissan Chemical Industries, Ltd. D, MIBK-SDMS, MIBK-SDL, and MIBK-SDZL, manufactured by JGC Catalysts and Chemicals; Examples include V8802 and V8803.

[0119] The silica particles may be spherical silica particles, but are preferably irregularly shaped silica particles. It is preferable to mix the spherical silica particles with the irregularly shaped silica particles. The term "spherical silica particles" refers to silica particles having a spherical shape, an oval spherical shape, or the like. In addition, "irregularly shaped silica particles" are potato-shaped (with an aspect ratio of 1.2 or more when observed in cross section). The irregularly shaped silica particles refer to silica particles having random irregularities on the surface. Since the surface area of ​​silica particles is larger than that of spherical silica particles, these irregularly shaped silica particles By containing the molecule, the contact area with the polyfunctional (meth)acrylate etc. is increased, The hardness of the hard coat layer can be improved. Whether the particles are irregularly shaped silica particles or not can be determined by observing the cross section of the hard coat layer with a transmission electron microscope (T This can be confirmed by observing the structure with a scanning electron microscope (EM) or scanning transmission electron microscope (STEM). can.

[0120] The average particle size of the silica particles is preferably 5 nm or more and 200 nm or less. If the particle size is less than nm, it becomes difficult to manufacture the particles themselves, and the particles may aggregate together. In addition, it may be extremely difficult to make the ink into a different shape. The irregular silica particles may have poor dispersibility and may aggregate. If the average particle size exceeds 200 nm, large irregularities will be formed in the hard coat layer, and the When the silica particles are spherical, problems such as an increase in noise may occur. In this case, the average particle size of the silica particles is measured by transmission electron microscopy (TEM) or scanning transmission electron microscopy (STEM). The particle sizes of 20 particles were measured from cross-sectional images of the particles taken using a microscope (STEM). The particle diameter of 20 particles is calculated as the arithmetic mean value. In the case of silica particles, the average particle size is measured by transmission electron microscopy (TEM) or scanning transmission electron microscope (STEM). From the cross-sectional image of the hard coat layer taken with an electron microscope (STEM), The maximum (long axis) and minimum (short axis) distances between the two points were measured, and the particle size was calculated by averaging. The particle size is the arithmetic mean value of the particle diameters of the particles.

[0121] The hardness of the first hard coat layer 12B can be controlled by controlling the size and amount of the inorganic particles. For example, when the first hard coat layer 12B is formed, The silica particles have a diameter of 5 nm or more and 200 nm or less, and the polymerizable compound is 100% by mass. The amount of the hydroxypropyl ether is preferably 25 to 60 parts by mass.

[0122] <Second hard coat layer> The second hard coat layer 12C is a layer for satisfying the above-mentioned continuous folding test. The second hard coat layer 12C has a sectional center of the second hard coat layer 12C. The Lutens hardness is preferably 375 MPa or more and 1500 MPa or less. If it is less than a, the scratch resistance of the hard coat layer may be insufficient. If the bending resistance exceeds 100%, the optical film will have insufficient bending resistance and will not be able to withstand the above-mentioned continuous folding test. The Martensitic property at the center of the cross section of the second hard coat layer 12C may not be satisfied. The lower limit of the hardness is more preferably 450 MPa or more, and the upper limit is 575 MPa or less. It is more preferable to do so.

[0123] The second hard coat layer 12C contains a resin. The second hard coat layer 12C includes The resin may further include inorganic particles dispersed therein.

[0124] (resin) The resin contains a polymer (cured product) of a polymerizable compound (curable compound). As the polyfunctional (meth)acrylate, polyfunctional (meth)acrylate is preferable. Examples of the polyfunctional (meth)acrylate include those similar to those in the section on the first hard coat layer 12B. In addition, the second hard coat layer 12C contains, in addition to the polyfunctional (meth)acrylate, and polyfunctional urethane (meth)acrylate and / or polyfunctional epoxy (meth)acrylate. It may also include.

[0125] (Inorganic particles) Examples of inorganic particles include the same inorganic particles as those in the column for the first hard coat layer 12B. The content of the inorganic particles in the second hard coat layer 12C is not particularly limited. However, for example, it is preferable that the content of the second hard coat layer 12C is 0 to 50% by mass. .

[0126] At least one of the first hard coat layer 12B and the second hard coat layer 12C may contain materials other than those mentioned above as long as the above Martens hardness is satisfied. For example, the resin component is preferably a polymerizable material that forms a cured product upon exposure to ionizing radiation. The polymerizable monomer or polymerizable oligomer may be contained. Examples of the monomer include (meth)acrylates having a radical polymerizable unsaturated group in the molecule. or (meth)acrylate oligomer having a radical polymerizable unsaturated group in the molecule. (Meth)acrylates having a radical polymerizable unsaturated group in the molecule. or (meth)acrylate oligomer having a radical polymerizable unsaturated group in the molecule. Examples of the copolymer include urethane (meth)acrylate and polyester (meth)acrylate. acrylate, epoxy (meth)acrylate, melamine (meth)acrylate, polyfluoro Monomers or oligomers such as alkyl (meth)acrylates and silicone (meth)acrylates These polymerizable monomers or oligomers may be used alone or in combination. Among them, polyfunctional (six or more functional) copolymers having a weight average molecular weight of 1 Urethane (meth)acrylates having a molecular weight of from 0.000 to 10,000 are preferred.

[0127] Hard coat layer 12 (first hard coat layer 12B and second hard coat layer 12C At least one of the above) contains an ultraviolet absorbing agent, a spectral transmittance adjusting agent, and / or an antifouling agent. It may further include.

[0128] <Ultraviolet absorbing agent> Optical films are used in mobile devices such as foldable smartphones and tablet computers. However, such mobile terminals are often used outdoors. Therefore, the polarizer placed on the display element side of the optical film is easily exposed to ultraviolet rays and deteriorates. However, since the resin layer is disposed on the display screen side of the polarizer, If the resin layer contains an ultraviolet absorbing agent, the polarizer may deteriorate due to exposure to ultraviolet light. The ultraviolet absorbing agent (UVA) can be effectively prevented from being included in the resin substrate 11 and and / or may be contained in the resin layer 13. In this case, the ultraviolet absorbing agent (UVA) may be However, it is not necessary that the hard coat layer 12 contains such a compound.

[0129] Examples of the ultraviolet absorbing agent include triazine-based ultraviolet absorbing agents and benzophenone-based ultraviolet absorbing agents. absorbents and benzotriazole-based ultraviolet absorbents.

[0130] Examples of the triazine-based ultraviolet absorber include 2-(2-hydroxy-4-[1- Octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl) )-1,3,5-triazine, 2-[4-[(2-hydroxy-3-dodecyloxypropionyl) Pyr)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl) )-1,3,5-triazine, 2,4-bis[2-hydroxy-4-butoxyphenyl] -6-(2,4-dibutoxyphenyl)-1,3,5-triazine, 2-[4-[(2- Hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4 ,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, and 2-[4- [(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl

[0036] -4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, etc. Commercially available triazine-based UV absorbers include, for example, TINUVIN 46 0, TINUVIN477 (both manufactured by BASF), LA-46 (manufactured by ADEKA) etc.

[0131] The benzophenone-based ultraviolet absorber may, for example, be 2-hydroxybenzophenone. , 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethox Dibenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy Hydroxy-4-methoxybenzophenone, Hydroxymethoxybenzophenone sulfonic acid and Examples thereof include its trihydrate and sodium hydroxymethoxybenzophenone sulfonate. Commercially available benzophenone-based UV absorbers include, for example, CHMASSORB8. 1 / FL (manufactured by BASF) and the like.

[0132] The benzotriazole-based ultraviolet absorber is, for example, 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol- 2-(2H-benzotriazol-2-yl)phenyl]propionate )-6-(linear and branched chain dodecyl)-4-methylphenol, 2-[5-chloro(2H) -Benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol , 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenyl 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-( 2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)benzotriazole Azole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5 -Chlorobenzotriazole, 2-(2'-hydroxy-3'-(3'',4'',5' ',6''-Tetrahydrophthalimidomethyl)-5'-methylphenyl)benzotriazole 2,2-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-( 2H-benzotriazol-2-yl)phenol) and 2-(2'-hydroxy- 3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, etc. Examples of commercially available benzotriazole-based ultraviolet absorbers include KE MISORB71D, KEMISORB79 (both manufactured by Chemipro Chemicals), JF-8 0, JAST-500 (both manufactured by Johoku Chemical Co., Ltd.), ULS-1933D (manufactured by Ichijo Co., Ltd.), RUVA-93 (Otsuka Chemical Co., Ltd.) and the like.

[0133] Among the ultraviolet absorbents, triazine-based ultraviolet absorbents and benzotriazole-based ultraviolet The ultraviolet absorbing agent is preferably used. The higher the disintegrability, the more preferable it is. Also, the less the bleeding after the above-mentioned continuous folding test is. It is preferable that the ultraviolet absorbing agent is polymerized or oligomerized. UV absorbers include those with benzotriazole, triazine, and benzophenone structures. Polymers or oligomers having the above structure are preferred. Specifically, benzotriazole and benzofuranolide are preferred. A (meth)acrylate having a phenol skeleton and methyl methacrylate (MMA) are optionally mixed. It is preferable that the organic light-emitting diode (OLED) is a thermal copolymer having a ratio of 1:1 or more. ) When applying optical films to display devices, UV absorbers protect OLEDs from UV rays. It can also play a role.

[0134] The content of the ultraviolet absorbing agent is not particularly limited, but may be any amount within the range of the solid content of the composition for the hard coat layer. It is preferable that the amount is 1 part by mass or more and 6 parts by mass or less per 100 parts by mass. In this case, the effect of incorporating the above-mentioned ultraviolet absorbing agent in the hard coat layer can be sufficiently obtained. If the amount exceeds 6 parts by mass, the hard coat layer may become significantly discolored or lose strength. The lower limit of the content of the ultraviolet absorber is more preferably 2 parts by mass or more, and even more preferably A more preferable upper limit is 5 parts by mass or less.

[0135] <Spectral transmittance adjuster> The spectral transmittance adjusting agent adjusts the spectral transmittance of the optical film. The layer 12 may be formed of, for example, a sesamol-type benzotriazole-based monomer represented by the following general formula (25): When the monomer is contained, the above-mentioned spectral transmittance can be satisfactorily satisfied. [ka] In the formula, R 7 R represents a hydrogen atom or a methyl group. 8 is a straight or branched chain with 1 to 6 carbon atoms represents a chain alkylene group or a linear or branched oxyalkylene group having 1 to 6 carbon atoms. vinegar.

[0136] The sesamol-type benzotriazole monomer is not particularly limited, but specifically The name of the substance is 2-[2-(6-hydroxybenzo[1,3]dioxole-5-yl] 2-[2-(6- Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazole-5 -yl]ethyl acrylate, 3-[2-(6-hydroxybenzo[1,3]dioxo 2H-benzotriazol-5-yl]propyl methacrylate, 3- [2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazole Azol-5-yl]propyl acrylate, 4-[2-(6-hydroxybenzo[1, 3]Dioxol-5-yl)-2H-benzotriazol-5-yl]butyl methacrylate Late, 4-[2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H -benzotriazol-5-yl]butyl acrylate, 2-[2-(6-hydroxybenzoyl) Benzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yloxy ]ethyl methacrylate, 2-[2-(6-hydroxybenzo[1,3]dioxole- 5-yl)-2H-benzotriazol-5-yloxy]ethyl acrylate, 2-[ 3-{2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzo Triazol-5-yl}propanoyloxy]ethyl methacrylate, 2-[3-{2- (6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol 4-[3-{2-(6-hydroxy-5-yl}propanoyloxy]ethyl acrylate (xybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl }propanoyloxy]butyl methacrylate, 4-[3-{ 2 -(6-hydroxybenzoyl {zo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl}propan noyloxy]butyl acrylate, 2-[3-{2-(6-hydroxybenzo[1,3 ]dioxol-5-yl)-2H-benzotriazol-5-yl}propanoyloxy 2-[3-{2-(6-hydroxybenzo[1,3]dioxa]ethyl methacrylate 2H-benzotriazol-5-yl}propanoyloxy]ethyl Acrylate, 2-(methacryloyloxy)ethyl 2-(6-hydroxybenzo[1 ,3]dioxol-5-yl)-2H-benzotriazole-5-carboxylate, 2 -(Acryloyloxy)ethyl 2-(6-hydroxybenzo[1,3]dioxole- 5-yl)-2H-benzotriazole-5-carboxylate, 4-(methacryloyl 2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-oxybutyl -Benzotriazole-5-carboxylate, 4-(acryloyloxy)butyl 2- (6-Hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol In addition, these sesamol-type benzotriesters can be used as benzotriesters. The riazole monomer may be used alone or in combination of two or more.

[0137] The sesamol-type benzotriazole monomer may be contained in the resin layer 13. However, in the case of a multi-layer structure having two or more resin layers, the above-mentioned separation is contained in one or more resin layers. For example, one of the resin layers may have a spectral transmittance of 380 nm. The above-mentioned sesamol-type benzotriazole monomer is contained so that only the transmittance can be achieved, Achieve the spectral transmittance conditions at wavelengths of 410 nm and 440 nm for other resin layers As described above, the composition contains the sesamol-type benzotriazole monomer. Furthermore, the resin layer is composed of three or more layers, and each resin layer satisfies the above-mentioned requirements for spectral transmittance. The above-mentioned sesamol-type benzotriazole monomer may be contained.

[0138] When the sesamol-type benzotriazole monomer is contained in the resin layer 13, e.g. For example, the sesamol-type benzotriazole monomer is present in an amount of 15 to 30% by mass out of 13 resin layers. It is preferable that the content of sesamol-type benzotriazole is in this range. By containing the above-mentioned monomer, the above-mentioned spectral transmittance can be satisfied. The sesamol-type benzotriazole monomer constitutes the resin layer 13. The resin component constituting the resin layer 13 may be reacted with the resin component and be contained therein integrally. It may be contained alone without reacting with the above.

[0139] <Anti-fouling agent> The antifouling agent may be uniformly dispersed in the hard coat layer, but a small amount of the agent may be sufficient. From the viewpoint of obtaining sufficient antifouling properties and suppressing the decrease in strength of the hard coat layer, It is preferable that the hard coat layer is unevenly distributed on the surface side of the hard coat layer. In the above, the antifouling agent can be unevenly distributed on the surface side of the hard coat layer by, for example, When forming the coating layer, a coating film formed using the composition for the hard coating layer is dried, Before curing, the coating is heated to reduce the viscosity of the resin components contained in the coating, making it easier to flow. The antifouling agent is concentrated on the surface side of the hard coat layer by increasing the mobility of the antifouling agent. By selecting and using a stain-resistant agent, the stain-resistant agent is floated on the surface of the coating without applying heat when the coating dries, and then A method of distributing the antifouling agent unevenly on the outermost surface side of the hard coat layer by curing the coating film is also available. In addition, when the hard coat layer has a multi-layer structure like the hard coat layer 12, By incorporating an antifouling agent in the hard coat layer on the surface side, an antifouling agent can be provided on the surface side of the hard coat layer. The fouling agent can be distributed unevenly.

[0140] The antifouling agent is not particularly limited, and examples thereof include silicone-based antifouling agents, fluorine-based antifouling agents, silicone Cone-based and fluorine-based antifouling agents are included, and each may be used alone or in combination. The antifouling agent may be an acrylic antifouling agent.

[0141] The content of the antifouling agent is 0.01 to 3.0 parts by mass per 100 parts by mass of the above-mentioned resin component. If the amount is less than 0.01 parts by mass, the resin layer may not have sufficient antifouling properties. If the amount exceeds 3.0 parts by mass, the hardness of the hard coat layer decreases. There is a risk that this may happen.

[0142] The antifouling agent preferably has a weight average molecular weight of 5,000 or less, and has excellent durability of antifouling performance. In order to improve the above, a compound having preferably one or more reactive functional groups, more preferably two or more reactive functional groups is used. In particular, by using an antifouling agent having two or more reactive functional groups, excellent resistance to dirt can be obtained. It is possible to impart scratch resistance.

[0143] When the antifouling agent does not have a reactive functional group, the antifouling agent can be used in the form of a sheet or a roll of optical film. Even in this case, the antifouling agent may transfer to the back side of the optical film when it is stacked, resulting in the optical film If you try to attach or apply other layers to the back side of the product, the other layers may peel off. Furthermore, it may easily peel off when subjected to multiple consecutive folding tests.

[0144] Furthermore, the antifouling agent having the above-mentioned reactive functional group is said to have good antifouling performance durability (durability). In particular, the hard coat layer containing the above-mentioned fluorine-based antifouling agent is less susceptible to fingerprints ( Furthermore, the surface of the composition for the hard coat layer is not easily visible, and the composition can be easily wiped off. The surface tension can be reduced, resulting in good leveling and a good appearance for the hard coat layer that is formed. will be favorable.

[0145] The hard coat layer containing a silicone-based antifouling agent has good slipperiness and good steel wool resistance. It is preferable to use an optical film containing such a silicone-based antifouling agent in the hard coat layer. The touch sensor has a better feel when touched by a finger or pen because it is smoother. In addition, fingerprints are less likely to be left on the hard coat layer (and are less noticeable), and they can be wiped off easily. Furthermore, the surface tension of the composition for the hard coat layer during application can be reduced, improving the leveling effect. The coating properties are good, and the appearance of the hard coat layer formed is good.

[0146] As a commercially available silicone-based antifouling agent, for example, SUA1900L10 (Shin-Nakamura Chemical Co., Ltd.) (manufactured by Shin-Nakamura Chemical Co., Ltd.), SUA1900L6 (manufactured by Shin-Nakamura Chemical Co., Ltd.), Ebecryl1360 (manufactured by Daicel Chemical Co., Ltd.), Tech Co., Ltd.), UT3971 (Nippon Synthetic Co., Ltd.), BYKUV3500 (BYK-Chemie Co., Ltd.) ), BYKUV3510 (manufactured by BYK), BYKUV3570 (manufactured by BYK ), X22-164E, X22-174BX, X22-2426, KBM503, KBM 5103 (Shin-Etsu Chemical Co., Ltd.), TEGO-RAD2250, TEGO-RAD2300, T EGO-RAD2200N, TEGO-RAD2010, TEGO-RAD2500, T EGO-RAD2600, TEGO-RAD2700 (manufactured by Evonik Japan), Mega Examples include FAC RS854 (manufactured by DIC).

[0147] Examples of commercially available fluorine-based antifouling agents include Optool DAC and Optool DSX. Ikin Industries), Megafac RS71, Megafac RS74 (DIC), LI NC152EPA, LINC151EPA, LINC182UA (Kyoeisha Chemical Co., Ltd.), Examples include Targent 650A, Ftargent 601AD, and Ftargent 602. do.

[0148] Commercially available fluorine- and silicone-based antifouling agents having reactive functional groups include, for example: Megafuck RS851, Megafuck RS852, Megafuck RS853, Megafuck RS854 (DIC), Opstar TU2225, Opstar TU2224 (J Examples of such compounds include X71-1203M (manufactured by Shin-Etsu Chemical Co., Ltd.) and X71-1203M (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0149] <<Resin layer>> The resin layer 13 is a layer made of a resin having optical transparency. The resin layer 13 has a shock absorbing property. The resin layer may have a multi-layer structure made up of two or more resin layers.

[0150] The thickness of the resin layer 13 is 50 μm or more and 300 μm or less. If it is less than 50 μm, the hardness of the resin layer may decrease. If the thickness is too thick, the film is not suitable for thinning and the processability may be deteriorated. The thickness of the resin layer was measured by photographing the cross section of the resin layer using a scanning electron microscope (SEM). The thickness of the resin layer was measured at 20 points in the cross-sectional image, and the arithmetic average value of the thicknesses at the 20 points was calculated. The method for taking a cross-sectional photograph of the resin layer is the same as that for the hard coat layer. The lower limit of the resin layer 13 is more preferably 60 μm or more, and the upper limit of the resin layer 13 is 1 It is more preferable that the thickness is 50 μm or less, and further preferably that the thickness is 100 μm or less.

[0151] The resin constituting the resin layer 13 is a resin having a temperature of 25° C. and 500 Hz or more in the optical film 10. The shear storage modulus G' and shear loss modulus G'' in the frequency range of 1000 Hz or less are within the above range. There is no particular limitation on the resin as long as it falls within the range. Examples of such resins include acrylic resins. gel, urethane gel, silicone gel, urethane resin, epoxy resin, etc. Among these, acrylic gels are preferred. "Gel" generally refers to a substance that has high viscosity. The resin layer 13 is made of acrylic gel, urethane resin, etc. In addition, rubber or a thermoplastic elastomer may be contained.

[0152] (Acrylic gel) Acrylic gels include acrylic ester-containing molybdenum gels, which are used in adhesives, etc. Various polymers can be used as long as they are polymerized from monomers. Examples of acrylic gels include ethyl (meth)acrylate, n-propyl (meth)acrylate, ) acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate , i-Butyl (meth)acrylate, 2-Ethylhexyl (meth)acrylate, n-Hexyl Amyl (meth)acrylate, n-amyl (meth)acrylate, i-amyl (meth)acrylate Acrylate, Octyl (meth)acrylate, i-Octyl (meth)acrylate, i- Myristyl (meth)acrylate, lauryl (meth)acrylate, nonyl (meth)acrylate acrylate, i-nonyl (meth)acrylate, i-decyl (meth)acrylate, tridecyl Sil(meth)acrylate, stearyl(meth)acrylate, i-stearyl(meth)acrylate Polymerized or copolymerized acrylic monomers such as acrylates can be used. In this specification, the term "(meth)acrylate" includes both "acrylate" and "methacrylate". The term "acrylic acid" includes both "acrylic acid esters" and "acrylic acid esters" used in the above (co)polymerization. The esters may be used alone or in combination of two or more kinds.

[0153] (Urethane resin) The urethane resin is a resin having a urethane bond. Cured products of radiation-curable urethane resin compositions and cured products of heat-curable urethane resin compositions, etc. Among these, from the viewpoints of obtaining high hardness, fast curing speed, and excellent mass productivity, Therefore, it is preferably a cured product of an ionizing radiation-curable urethane resin composition.

[0154] The ionizing radiation curable urethane resin composition contains a urethane (meth)acrylate. The thermosetting urethane resin contains a polyol compound and an isocyanate compound. Urethane (meth)acrylate, polyol compound, and isocyanate compound may be any one of a monomer, an oligomer, and a prepolymer.

[0155] The number of (meth)acryloyl groups (functional groups) in the urethane (meth)acrylate is 2 or less. It is preferable that the number of (meth)acryloyl groups in the urethane (meth)acrylate is 4 or less. If the number of alkyl groups is less than 2, the pencil hardness may be low. The shrinkage increases, causing the optical film to curl, and the resin layer to crack when folded. The (meth)acryloyl group in the urethane (meth)acrylate may cause The upper limit of the number is more preferably 3 or less. The term "acryloyl group" refers to a group that includes both an "acryloyl group" and a "methacryloyl group."

[0156] The weight average molecular weight of the urethane (meth)acrylate is 1,500 or more and 20,000 or less. It is preferable that the weight average molecular weight of the urethane (meth)acrylate is less than 1,500. If it is more than 20,000, the impact resistance may decrease, and if it exceeds 20,000, the ionizing radiation hardening may occur. The viscosity of the urethane resin composition increases, and the coating properties may deteriorate. p) The lower limit of the weight average molecular weight of the acrylate is more preferably 2000 or more, and the upper limit of The limit is more preferably 15,000 or less.

[0157] In addition, examples of repeating units having a structure derived from urethane (meth)acrylate include Examples of such a structure include those represented by the following general formula (26), (27), (28) or (29). can be. [ka] In the above general formula (26), R 9 represents a branched alkyl group, and R 10 is a branched alkyl R represents a group or a saturated cyclic aliphatic group; 11 represents a hydrogen atom or a methyl group, R 12 is hydrogen atom, a methyl group, or an ethyl group; m is an integer of 0 or more; x is an integer of 0 to 3. .

[0158] [ka] In the above general formula (27), R 9 represents a branched alkyl group, and R 10 is a branched alkyl R represents a group or a saturated cyclic aliphatic group; 11 represents a hydrogen atom or a methyl group, R 12 is hydrogen atom, a methyl group, or an ethyl group; n is an integer of 1 or more; x is an integer of 0 to 3. .

[0159] [ka] In the above general formula (28), R 9 represents a branched alkyl group, and R 10 is a branched alkyl R represents a group or a saturated cyclic aliphatic group; 11 represents a hydrogen atom or a methyl group, R 12 is hydrogen atom, a methyl group, or an ethyl group; m is an integer of 0 or more; x is an integer of 0 to 3. .

[0160] [ka] In the above general formula (29), R 9 represents a branched alkyl group, and R 10 is a branched alkyl R represents a group or a saturated cyclic aliphatic group; 11 represents a hydrogen atom or a methyl group, R 12 is hydrogen atom, a methyl group, or an ethyl group; n is an integer of 1 or more; x is an integer of 0 to 3. .

[0161] In addition, the resin constituting the resin layer 13 may have any structure of a polymer chain (repeating unit). The resin layer 13 is formed by, for example, pyrolysis GC-MS and FT-IR. In particular, the pyrolysis GC-MS can be used to determine whether the resin layer 13 is This is useful because it allows the detection of monomer units that are generated as monomer components.

[0162] The resin layer 13 is a layer that is heated to a temperature of 25° C. and 500 Hz or higher and 1000 Hz or lower in the optical film 10. The shear storage modulus G' and shear loss modulus G'' in the lower frequency range are within the above range. For example, ultraviolet absorbers, spectral transmittance adjusters, antifouling agents, inorganic particles and / or organic particles, etc. The ultraviolet absorbing agent may be the ultraviolet absorbing agent described in the section of the hard coat layer 12. Since a similar one can be used, the description thereof will be omitted here.

[0163] <<<Other optical films>>> In the optical film 10 shown in FIG. 1, the resin layer 13 is disposed on the second surface 1 of the resin substrate 11. 1B, but as an optical film, the resin layer is attached to the resin substrate via an adhesive layer. Specifically, the optical film shown in FIG. The film 40 is made up of a resin substrate 11 and a hard coat layer provided on the first surface 11A of the resin substrate 11. The layer 12 is provided on the second surface 11B side of the resin substrate 11, which is the surface opposite to the first surface 11A. and an adhesive layer 41 interposed between the resin substrate 11 and the resin layer 13. The resin layer 13 is attached to the resin substrate 11 via an adhesive layer 41. In FIG. 5, the same reference numerals as in FIG. 1 denote the same members as those shown in FIG. Therefore, the description will be omitted.

[0164] In FIG. 5, the surface 40A of the optical film 40 is the surface 12A of the hard coat layer 12. The rear surface 40B of the optical film 40 is the resin layer 13 on the resin base material 11 side. The opposite surface is surface 13A.

[0165] Optical Film 40 also exhibits the same optical properties at 25°C and in the frequency range of 500Hz to 1000Hz. The shear storage modulus G' of the material is greater than 200 MPa and less than 1200 MPa at 25°C. The shear loss modulus G´´ in the frequency range of 500Hz to 1000Hz is 3MPa or less. The shear storage modulus G' and the shear storage modulus G' of the optical film 40 are 150 MPa or less. The shear loss modulus G'' is the shear storage modulus G' and the shear loss in the optical film 10. The elastic modulus G'' shall be measured in the same manner. Other properties of the optical film 40 The properties are similar to those of the optical film 10, so the description will be omitted here.

[0166] <<Adhesive layer>> The adhesive layer 41 may be an adhesive film. The adhesive layer 41 is not particularly limited. However, for example, OCA (Optical Clear Adhesive) can be used. If the thickness of the adhesive layer 41 is 5 μm or more, the resin The resin layer 13 can be reliably attached to the substrate 11. From the viewpoint of miniaturization, it is preferably 50 μm or less.

[0167] <<Optical film manufacturing method>> The optical film 10 can be produced by various methods depending on the type of resin that constitutes the resin layer 13. For example, when the resin layer 13 is a layer made of an acrylic gel, For example, it can be produced as follows. First, the first surface 11A of the resin base material 11 is A first hard coat layer composition is applied onto the first hard coat layer by a coating device such as a bar coater, A coating film of the composition for the first hard coat layer is formed.

[0168] <First hard coat layer composition> The first hard coat layer composition is polymerized to form the first hard coat layer 12B. The composition for the first hard coat layer may further contain, as necessary, an ultraviolet ray absorbing compound. Contains radiation absorbers, spectral transmittance adjusters, antifouling agents, inorganic particles, leveling agents, solvents, and polymerization initiators. It's okay to do that.

[0169] (solvent) The solvent may be alcohol (e.g., methanol, ethanol, propanol, isopropanol, etc.). propyl alcohol, n-butanol, s-butanol, t-butanol, benzyl alcohol, PGME, ethylene glycol, diacetone alcohol), ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, Tanone, diisobutyl ketone, diethyl ketone, diacetone alcohol), esters (acetic acid Methyl acetate, ethyl acetate, butyl acetate, n-propyl acetate, isopropyl acetate, methyl formate , PGMEA), aliphatic hydrocarbons (e.g., hexane, cyclohexane), halogenated hydrocarbons Hydrocarbons (e.g., methylene chloride, chloroform, carbon tetrachloride), aromatic hydrocarbons (e.g., benzene benzene, toluene, xylene), amides (e.g., dimethylformamide, dimethylacetamide ether (e.g., diethyl ether, dioxane, tetrahydrofuran, Ether alcohol (e.g., 1-methoxy-2-propanol), carbonyl alcohol (e.g., 1-methoxy-2-propanol), These solvents include dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. The solvent may be used alone or in combination of two or more kinds. In this case, components such as urethane (meth)acrylate and other additives are dissolved or dispersed. In addition, methyl isobutyl ketone is preferred in that the composition for the first hard coat layer can be suitably applied. Methyl ethyl ketone is preferred.

[0170] (Polymerization initiator) The polymerization initiator is decomposed by irradiation with ionizing radiation to generate radicals, which promote the polymerization of the polymerizable compound. It is a component that initiates or advances cross-linking.

[0171] A polymerization initiator is a substance that releases a radical polymerization initiator when exposed to ionizing radiation. There is no particular limitation as long as it is possible. The polymerization initiator is not particularly limited, and a known one may be used. Specific examples include acetophenones, benzophenones, Michler's compounds, and the like. Benzoyl benzoates, α-amyloxime esters, thioxanthones, propionyl Non-type compounds, benzil-type compounds, benzoin-type compounds, and acylphosphine oxide-type compounds. It is preferable to use a mixture of photosensitizers, and specific examples thereof include n-butyl aldehyde. amine, triethylamine, poly-n-butylphosphine, etc.

[0172] After forming the coating film of the composition for the first hard coat layer, the coating film is delaminate|sealed by various known methods, for example, For example, the film is dried by heating at a temperature of 30°C or higher and 120°C or lower for 10 to 120 seconds. The solvent is evaporated.

[0173] After the coating is dried, it is irradiated with ionizing radiation such as ultraviolet light to semi-harden the coating (half-curing). In this specification, "semi-curing" refers to curing that occurs when further irradiated with ionizing radiation. However, at this stage, the coating film is not fully cured (full cure). In this specification, the term "complete curing" refers to a state in which the resin composition is completely cured even if it is further irradiated with ionizing radiation. This means that curing does not substantially proceed.

[0174] After the coating is semi-cured, a second hard coat is applied to the coating using a coating device such as a bar coater. A composition for a second hard coat layer for forming a coating layer 12C is applied to form a second hard coat layer. A coating film of the composition for the hard coat layer is formed.

[0175] <Composition for second hard coat layer> The composition for the second hard coat layer is polymerized to form the second hard coat layer 12C. The composition for the second hard coat layer may further contain, as necessary, an ultraviolet ray resistant compound. The composition for the second hard coat layer may contain a radiation absorbing agent, a solvent, and a polymerization initiator. As with the composition for a hard coat layer (1), the total solid content is preferably 25 to 55%. The solvent and the polymerization initiator are the same as those described in the first hard coat layer composition. Since the above-mentioned agent is similar to the agent, the description thereof will be omitted here.

[0176] After forming the coating film of the composition for the second hard coat layer, the coating film is, for example, Dry and dissolve by heating at a temperature between 30℃ and 120℃ for 10 to 120 seconds. The agent is allowed to evaporate.

[0177] After drying the coating film, the coating film of the composition for the second hard coat layer is exposed to ionizing radiation such as ultraviolet rays. The coating film of the composition for the first hard coat layer and the coating film of the composition for the second hard coat layer are formed by irradiation. The coating film is fully cured to form the first hard coat layer 12B and the second hard The coating layer 12C is formed to obtain the hard coating layer 12. Then, the hard coating layer 12 is A composition for a resin layer is applied to the second surface 11B of the formed resin substrate 11, A coating film of the composition is formed.

[0178] <Composition for resin layer> The resin layer composition contains, for example, urethane (meth)acrylate. The composition may further contain, as necessary, an ultraviolet absorber, a spectral transmittance adjuster, a leveling agent, a solvent, etc. The solvent and the polymerization initiator may be contained in the first hard coat layer composition. The same solvents and polymerization initiators as explained in the above section can be used.

[0179] After forming a coating film of the resin composition, the coating film is dried and then irradiated with ionizing radiation, The coating of the resin layer composition is cured to form a resin layer 13. This results in the photoresist layer 13 shown in FIG. 10 academic films are obtained.

[0180] In addition, when obtaining the optical film 40 shown in FIG. 5, first, a resin is formed in the same manner as described above. A hard coat layer 12 is formed on a first surface 11A of the resin substrate 11.

[0181] On the other hand, a resin is applied to one side of a release film such as a polyethylene terephthalate film. After the composition for the oil layer is applied to form a coating film, it is dried and then irradiated with ionizing radiation. Thus, the coating of the resin layer composition is cured to form the resin layer 13 .

[0182] After forming the resin layer 13 on the release film, the release film is peeled off from the resin layer 13, A single resin layer 13 is obtained. Then, the obtained resin layer 13 is attached to the resin substrate 1 via the adhesive layer 41. 1. In this way, the optical film 40 shown in FIG. 5 is obtained. can be.

[0183] <<<Image display devices>>> The optical films 10 and 40 can be incorporated into a foldable image display device. FIG. 6 is a schematic diagram of an image display device according to this embodiment. As shown in FIG. 1, the image display device 50 has a housing 51 that mainly houses a battery and the like, facing the observer side. , a protective film 52, a display panel 53, a touch sensor 54, a circular polarizing plate 55, and an optical filter. The film 10 is laminated in this order. Between the sensor 54 and the circular polarizing plate 55, and between the circular polarizing plate 55 and the optical film 10, a light-transmitting The adhesive layer 56 is disposed on the substrate 1 and is fixed to the substrate 1 by the adhesive layer 56. In addition, a black layer 57 is provided on a part of the back surface 10B of the optical film 10. The adhesive layer 56 is disposed between the display panel 53 and the touch sensor 54, and between the touch sensor 54 and the display panel 53. 4 and the circular polarizing plate 55, and between the circular polarizing plate 55 and the optical film 10. The location of the adhesive layer is not particularly limited as long as it is between the optical film and the display panel.

[0184] The optical film 10 is formed such that the hard coat layer 12 is closer to the viewer than the resin substrate 11. In the image display device 50, the hard coat layer 12 of the optical film 10 is The surface 12A (the surface of the second hard coat layer 12C) is the surface 50A of the image display device 50. It is composed of:

[0185] In the image display device 50, the display panel 53 is made of organic light-emitting diodes or the like. The touch sensor 54 is a light-emitting diode panel. 53 side, but may be disposed between the circular polarizing plate 55 and the optical film 10. The touch sensor 54 may be of an on-cell type or an in-cell type.

[0186] The adhesive layer 56 may be, for example, OCA (Optical Clear Adhesive). However, in order to improve the impact resistance and prevent damage to the display panel 53, the acrylic gel It is preferable to use an adhesive layer made of the above-mentioned acrylic gel for the adhesive layer 56. When an adhesive layer is used, the adhesive layer is provided between the display panel 53 and the touch sensor 54, and between the touch sensor 54 and the At least one of the above-mentioned portions is provided between the circular polarizing plate 55 and the optical film 10, and between the circular polarizing plate 55 and the optical film 10. In addition, since the acrylic gel has adhesive properties, the resin layer 13 can be easily attached to the acrylic gel. In the case where the circularly polarizing plate 55 is made of the acrylic gel, an adhesive layer is provided between the circularly polarizing plate 55 and the optical film 10. Even if 56 is not provided, the resin layer 13 can be directly attached to the circular polarizing plate 55 to obtain a circularly polarized light. The plate 55 and the optical film 10 can be fixed together.

[0187] The shear loss tangent tanδ has been known as an index of shock absorption performance. Therefore, the resin substrate has a hard coat layer on one side and a resin layer on the other side. It is possible to express the impact resistance of optical films made of this material in terms of shear loss tangent tan δ, but In the shear loss tangent tanδ, an impact is applied to the surface of the optical film (the surface of the hard coat layer). When the optical film is heated, the optical film itself may cause depressions on the surface of the optical film, and the adhesive layer may cause depressions on the surface of the optical film. The recess on the surface of the optical film and the member located inside the image display device relative to the optical film This is because the shear loss tangent tanδ is smaller than the shear loss elasticity. This is thought to be due to the ratio of the elastic modulus G´ to the shear storage modulus G´ (G´ / G´). As a result of further intensive research, the inventors of the present invention found that when an impact is applied to the surface of an optical film, The surface depressions caused by the optical film itself and the adhesive layer, In order to prevent damage to the components located inside the image display device rather than the film, It was found that the balance between the membrane thickness, the shear storage modulus G´ and the shear loss modulus G´´ is important. According to this embodiment, the hard coat layer 12 and the reflective layer 13 are formed on the first surface 11A side of the resin substrate 11. In the optical films 10 and 40 having a structure in which the resin layer 13 is provided on the second surface 11B side, The thickness of the oil layer 13 is thin, ranging from 50 μm to 300 μm, and the optical film 10, 4 The shear storage modulus G' at 0 is greater than 200 MPa and less than 1000 MPa. The shear loss modulus G'' of the optical film 10 or 40 is 3 MPa or more. Since the resistance is 50 MPa or less, the optical film 10 can be folded while maintaining its surface When an impact is applied to the optical film 10, 40, the surface 10A, 40 The adhesive layer 56 is located inside the image display device 50 rather than the depression at A and the optical film 10. It is possible to suppress the depressions on the surfaces 10A and 40A of the optical films 10 and 40 caused by the above. In addition, damage to components such as the display panel 53 located inside the image display device 50 can be suppressed. This provides excellent impact resistance. EXAMPLES

[0188] In order to explain the present invention in detail, the following examples are given. The "solid content equivalent to 100%" below refers to the solid content in the solvent-diluted product. This is the value when minutes is 100%.

[0189] <Preparation of composition for hard coat layer> First, the components were mixed to obtain the composition shown below to obtain a composition for a hard coat layer. .

[0190] (Hardcoat layer composition 1) Dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate Mixture of cellulose acetate (product name "M403", manufactured by Toa Gosei Co., Ltd.): 25 parts by weight Dipentaerythritol EO modified hexaacrylate (product name: A-DPH-6E, Shin Nakamura Chemical Co., Ltd.): 25 parts by mass -Irregular silica particles (average particle size 25 nm, manufactured by JGC Catalysts and Chemicals): 50 parts by weight (solid content 10 0% conversion value) Photopolymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacu re(registered trademark) 184" (BASF Japan): 4 parts by weight Fluorine-based leveling agent (product name "F568", manufactured by DIC): 0.2 parts by weight (1 part solids) 00% conversion value) Methyl isobutyl ketone (MIBK): 150 parts by weight

[0191] (Hardcoat layer composition 2) Urethane acrylate (product name "UX5000", manufactured by Nippon Kayaku Co., Ltd.): 25 parts by weight Dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate Mixture of cellulose acetate (product name "M403", manufactured by Toa Gosei Co., Ltd.): 50 parts by weight Multifunctional acrylate polymer (product name "Acrylit 8KX-012C", Taisei Fine Chemical Co., Ltd.): 25 parts by weight (based on 100% solids) Antifouling agent (product name "BYKUV3500", manufactured by BYK-Chemie): 1.5 parts by weight (solid content (100% conversion value) Photopolymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacu re(registered trademark) 184" (BASF Japan): 4 parts by weight Methyl isobutyl ketone (MIBK): 150 parts by weight

[0192] <Preparation of Resin Layer Composition> First, the components were mixed so as to obtain the composition shown below, thereby obtaining a composition for a resin layer. (Composition 1 for resin layer) Urethane acrylate (product name "UV3310B", Nippon Synthetic Chemical Industry Co., Ltd., bifunctional): 8 5 parts by mass Phenoxyethyl acrylate (product name: Viscoat #192, Osaka Organic Chemical Industry Co., Ltd.) ): 5 parts by mass Tripentaerythritol acrylate, mono- and dipentaerythritol acrylate Polymenthaerythritol acrylate and polymenthaerythritol acrylate mixture (product name: Viscoat # 802, manufactured by Osaka Organic Chemical Industry Co., Ltd.): 10 parts by mass Polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacur e(registered trademark) 184" manufactured by BASF Japan Ltd.): 5 parts by weight Methyl isobutyl ketone: 10 parts by weight

[0193] (Composition 2 for resin layer) Urethane acrylate (product name "UV3310B", Nippon Synthetic Chemical Industry Co., Ltd., bifunctional): 8 5 parts by mass Phenoxyethyl acrylate (product name: Viscoat #192, Osaka Organic Chemical Industry Co., Ltd.) ): 15 parts by mass Polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacur e(registered trademark) 184" manufactured by BASF Japan Ltd.): 5 parts by weight Methyl isobutyl ketone: 10 parts by weight

[0194] (Composition 3 for resin layer) Urethane acrylate (product name "UV3310B", Nippon Synthetic Chemical Industry Co., Ltd., bifunctional): 8 0 parts by mass Phenoxyethyl acrylate (product name: Viscoat #192, Osaka Organic Chemical Industry Co., Ltd.) ): 5 parts by mass Tripentaerythritol acrylate, mono- and dipentaerythritol acrylate Polymenthaerythritol acrylate and polymenthaerythritol acrylate mixture (product name: Viscoat # 802, manufactured by Osaka Organic Chemical Industry Co., Ltd.): 10 parts by mass Dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate Mixture of glycerol and glycerol (product name: "KAYARAD DPHA", manufactured by Nippon Kayaku Co., Ltd.): 5 parts by weight Polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacur e(registered trademark) 184" manufactured by BASF Japan Ltd.): 5 parts by weight Methyl isobutyl ketone: 10 parts by weight

[0195] (Composition 4 for resin layer) Urethane acrylate (product name "UV3310B", Nippon Synthetic Chemical Industry Co., Ltd., bifunctional): 9 5 parts by mass Phenoxyethyl acrylate (product name: Viscoat #192, Osaka Organic Chemical Industry Co., Ltd.) ): 5 parts by mass Polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacur e(registered trademark) 184" manufactured by BASF Japan Ltd.): 5 parts by weight Methyl isobutyl ketone: 10 parts by weight

[0196] (Composition for resin layer 5) Urethane acrylate (product name "UV3310B", Nippon Synthetic Chemical Industry Co., Ltd., bifunctional): 8 5 parts by mass Dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate Mixture of glycerol and glycerol (product name: "KAYARAD DPHA", manufactured by Nippon Kayaku Co., Ltd.): 15 mass Department Polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacur e(registered trademark) 184" manufactured by BASF Japan Ltd.): 5 parts by weight Methyl isobutyl ketone: 10 parts by weight

[0197] <Example 1> The resin substrate was a 50 μm thick polyimide substrate (product name: Neoprim, Mitsubishi Gas Chemical Co., Ltd.). A hard coat was applied to the first surface of the polyimide substrate using a bar coater. The coating layer composition 1 was applied to form a coating film. The coating film was then heated at 70° C. The solvent in the coating is evaporated by heating for one minute, and then the coating is exposed to ultraviolet light (Fusion) The UV light source is H bulb (manufactured by UV System Japan) and the integrated light intensity is 1 00mJ / cm 2 The coating was then semi-cured by irradiating the coating with light so that the coating was half-cured. A hard coat layer is formed on the surface of the semi-cured coating of the composition 1 for hard coat layer with a bar coater. The coating film was heated at 70° C. for 1 minute. By this, the solvent in the coating is evaporated, and then the ultraviolet irradiation device (Fusion UV System Ja Using a light source H bulb manufactured by Pan Co., Ltd., ultraviolet rays were irradiated under conditions of oxygen concentration of 200 ppm or less. Accumulated light intensity: 200mJ / cm 2 The coating is then fully cured by irradiating it until it becomes As a result, a first hard coat layer having a thickness of 10 μm and a first A hard coat layer having a thickness of 5 μm is laminated on the hard coat layer. After the hard coat layer was formed on the polyimide substrate, the polyimide substrate was A resin layer composition 1 is applied to a second surface opposite to the first surface by a bar coater to form a coating film. The formed coating film was then heated at 70°C for 1 minute to remove the oxidized film. The solvent was evaporated, and the ultraviolet irradiation device (Fusion UV System Japan, light source H-Ba UV light was emitted in air at an integrated dose of 1200 mJ / cm 2 Irradiation so that The coating is then cured to form a resin layer made of a urethane resin having a thickness of 200 μm. An optical film was obtained.

[0198] The thickness of each layer was measured by photographing the cross section of each layer using a scanning electron microscope (SEM). The thickness of each layer was measured at 20 points in each image, and the arithmetic mean value of the thicknesses at those 20 points was calculated. The specific method for taking cross-sectional photographs was as follows. First, cut the specimen into 1 mm x 10 mm pieces. The optical film was embedded in an embedding resin to prepare a block, and the block was then The slices are uniform and free of holes, with a thickness of 70 nm to 100 nm, using the general sectioning method. To prepare the sections, we used the Ultramicrotome EM UC7 (Leica Microtome). A uniform section without holes was cut out. The remaining block was used as the measurement sample. Using the "S-4800" manufactured by Hitachi High-Technologies Corporation, the cross section of the measurement sample When taking cross-sectional photographs using the S-4800, the detector was set to "SE The cross-sectional observation was performed with the acceleration voltage set to “5 kV” and the emission current set to “10 μA.” Regarding magnification, adjust the focus and contrast and brightness to see if each layer can be distinguished. The magnification was adjusted appropriately from 100 to 100,000 while observing. In addition, the aperture was adjusted to the "Beam Monitor Aperture 3", objective lens aperture 3, and WD 8mm. The thickness of the polyimide substrate was also measured in the same manner as the thickness of each layer. In Example 6 and Comparative Examples 1 to 5, the thickness and hardness of the substrate were measured in the same manner as in Example 1. The thickness of the coating layer and the resin layer were measured.

[0199] <Example 2> In Example 2, the same procedure as in Example 1 was carried out except that the thickness of the resin layer was 50 μm. Thus, an optical film was obtained.

[0200] <Example 3> In Example 3, the same procedure as in Example 1 was carried out except that the thickness of the resin layer was 300 μm. Thus, an optical film was obtained.

[0201] <Example 4> In Example 4, except that resin layer composition 2 was used instead of resin layer composition 1, An optical film was obtained in the same manner as in Example 1.

[0202] <Example 5> In Example 5, except that resin layer composition 3 was used instead of resin layer composition 1, An optical film was obtained in the same manner as in Example 1.

[0203] <Example 6> The resin substrate was a 50 μm thick polyimide substrate (product name: Neoprim, Mitsubishi Gas Chemical Co., Ltd.). A hard coat layer composition was applied to the first surface of the polyimide substrate using a bar coater. The coating film was then heated at 70°C for 1 minute. By applying heat to the paint, the solvent in the paint film is evaporated, and then the UV irradiation device (Fusion UV System) The ultraviolet light was emitted in air with an integrated light intensity of 100 mJ / cm2 using a light source (H bulb, manufactured by Japan Co., Ltd.). 2 The coating was then semi-cured by irradiating it until it was half-cured. The hard coat layer composition 2 is applied to the surface of the coating film of the hard coat layer composition 1 with a bar coater. The coating film was then heated at 70°C for 1 minute to form a coating film. The solvent in the film is evaporated, and the film is then exposed to ultraviolet light (Fusion UV System Japan, light source). Using a H bulb, ultraviolet light was emitted at an integrated light intensity of 200 Hz under conditions of oxygen concentration of 200 ppm or less. 0mJ / cm 2 The coating was completely cured by irradiating it until it reached a temperature of 100°C. A first hard coat layer having a thickness of 10 μm is formed on a polyimide substrate. A hard coat layer is formed by laminating a second hard coat layer having a thickness of 5 μm on the layer. did.

[0204] On the other hand, a 100 μm thick polyethylene terephthalate film was used as a release film. (Product name: Cosmoshine A4100, manufactured by Toyobo Co., Ltd.) The resin layer composition 1 was applied to the formed coating film. The solvent in the coating is evaporated by heating at 0°C for 1 minute, and then the coating is exposed to ultraviolet light (fuser). The UV light was emitted in air using a light source (H bulb manufactured by Epson UV Systems Japan). is 1200mJ / cm 2 The coating is hardened by irradiating it until the film thickness becomes 200 μm. After the resin layer was formed, a polyethylene terephthalate layer was The adhesive film was peeled off from the resin to obtain a single resin layer.

[0205] Then, a 5 μm thick adhesive film was applied to the second surface of the polyimide substrate, which is opposite to the first surface. A resin layer is attached via a layer (product name "Panaclean PD-S1", manufactured by Panac Corporation). Thus, an optical film was obtained.

[0206] <Comparative Example 1> In Comparative Example 1, the same procedure as in Example 1 was followed except that the thickness of the resin layer was 350 μm. Thus, an optical film was obtained.

[0207] <Comparative Example 2> In Comparative Example 2, the same procedure as in Example 1 was carried out except that the thickness of the resin layer was 30 μm. Thus, an optical film was obtained.

[0208] <Comparative Example 3> In Comparative Example 3, an optical film was obtained in the same manner as in Example 1, except that Composition 4 for resin layer was used instead of Composition 1 for resin layer. An optical film was obtained in the same manner as in Example 1.

[0209] <Comparative Example 4> In Comparative Example 4, an optical film was obtained in the same manner as in Example 1, except that Composition 5 for resin layer was used instead of Composition 1 for resin layer. An optical film was obtained in the same manner as in Example 1.

[0210] <Measurement of G´, G´´, and tanδ> The shear storage modulus G´, the shear loss modulus G´´, and the shear loss tangent tanδ of the optical films according to the examples and comparative examples were measured. Specifically, first, the optical film was punched into a rectangular shape of 10 mm × 5 mm to obtain a sample. Then, two such samples were prepared and attached to a solid shear jig, which is an option of a dynamic viscoelasticity measuring device (product name: "Rheogel-E4000", manufactured by UBM Co., Ltd.). Specifically, the solid shear jig includes a 1-mm-thick metal solid shear plate and two L-shaped metal fittings arranged on both sides of the solid shear plate. One sample was sandwiched between the solid shear plate and one L-shaped metal fitting, and the other sample was sandwiched between the solid shear plate and the other L-shaped metal fitting. In this case, the resin layer was on the solid shear plate side, and the hard coat layer was on the L-shaped metal fitting side. Then, the L-shaped metal fittings were tightened with screws to fix the samples. Next, a tensile test chuck consisting of an upper chuck and a lower chuck was attached to the dynamic viscoelasticity measuring device (product name: "Rheogel-E4000", manufactured by UBM Co., Ltd., Inc.). Then, the solid shear jig was installed between the upper chuck and the lower chuck at a chuck separation of 20 mm. The set temperature was 25°C, and the temperature was increased at a rate of 2°C / min. 、および剪断損失正接tanδを測定した。具体的には、まず、光学フィルムを10mm ×5mmの長方形状に打ち抜いて、サンプルとした。そして、このサンプルを2枚準備し 、動的粘弾性測定装置(製品名「Rheogel-E4000」、ユービーエム社製)のオプションで ある固体剪断用治具に取り付ける。具体的には、固体剪断用治具は、厚みが1mmの1枚 の金属製の固体剪断板と、この固体剪断板の両側に配置された2つのL型金具を備えてお り、固体剪断板と一方のL型金具との間で一方のサンプルを挟み、かつ固体剪断板と他方 のL型金具で他方のサンプルを挟んだ。この場合、樹脂層が固体剪断板側となり、ハード コート層がL型金具側となるようにサンプルを挟んだ。そして、ビスでL型金具間を締め て、サンプルを固定した。次いで、動的粘弾性測定装置(製品名「Rheogel-E4000」、株 式会社ユービーエム社製)に上部チャックおよび下部チャックからなる引張り試験用チャ ックを取り付けた後、上部チャックと下部チャックの間に固体剪断用治具をチャック間距 離20mmで設置した。そして、設定温度を25℃とし2℃ / minで昇温させた。この In this state, the solid shear plate is fixed and two L-shaped metal fittings are subjected to a strain of 1% and a frequency of 500 Hz or less. The dynamic viscoelasticity of a solid is measured at 25°C while applying vertical vibrations in the range of 1000 Hz or less. , the shear storage modulus G´, the shear loss modulus G´´ and the shear loss tangent tan Here, the frequency of the optical film is 500 Hz or more and 1000 Hz or less. The shear storage modulus G´, shear loss modulus G´´ and shear loss tangent tanδ in the L-type The metal fittings were subjected to vertical vibrations of 500Hz, 750Hz, and 950Hz, respectively. The shear storage modulus G´, shear loss modulus G´ and shear The loss tangent tanδ was measured, and the shear storage modulus G´, shear loss modulus G´ and The arithmetic mean value of the shear loss tangent tanδ was calculated, and this measurement was repeated three times. The three obtained arithmetic mean values ​​were further arithmetically averaged to obtain a value.

[0211] <Impact resistance test> The resin layer is applied to the surface of 0.7mm thick soda glass, with the soda glass side facing the resin layer. The optical films according to the examples and the comparative examples were placed directly on the test piece, weighing 100 g, at a height of 30 cm. Impact resistance test A in which an iron ball with a diameter of 30 mm is dropped onto the surface of the hard coat layer of an optical film Each step was repeated three times. In addition, the soda glass was placed on a 0.7 mm thick soda glass with the resin layer facing the soda glass. The optical films according to the examples and comparative examples were attached to a 200 μm thick adhesive sheet ( Product name: "Highly transparent double-sided tape 8146-2" (manufactured by 3M) and place it at a height of 30 An iron ball weighing 100 g and having a diameter of 30 mm was dropped from a position of 1 cm onto the surface of the hard coat layer of the optical film. In impact resistance tests A and B, the test piece was dropped onto a steel surface three times each. The position where the ball was dropped was changed each time. In the film, the presence or absence of depressions on the surface of the hard coat layer was evaluated by visual inspection. In addition, the soda glass was evaluated for cracks. The film was visually evaluated for the presence or absence of depressions on the surface of the hard coat layer. The evaluation results were as follows: (Evaluation of dents on the surface of the hard coat layer) ○: When the hard coat layer is observed from the front and obliquely, the hard coat No depressions were observed on the surface of the layer. △: When the hard coat layer is observed from the front, a dent is observed on the surface of the hard coat layer. However, when observed obliquely, depressions were observed on the surface of the hard coat layer. ×: When the hard coat layer is observed from the front and obliquely, the hard coat Obvious pitting was observed on the surface of the layer. (Soda glass cracking evaluation) ◎: The soda glass did not break. ○: The soda glass was scratched but did not break. △: The soda glass cracked once or twice. ×: The soda glass cracked all three times.

[0212] <Continuous folding test> The optical films according to the examples and comparative examples were cut into rectangles of 30 mm x 100 mm. The samples were then subjected to a durability test using a Yuasa System Co., Ltd. The short sides (30 mm) of the samples were fixed to the fixing parts of a test piece (manufactured by the company) and the sample was placed in the test piece as shown in Figure 3(C). The sample is then attached so that the minimum distance between the two opposing sides is 30 mm. A continuous folding test in which the hard coat layer side of the pulley is folded 180 degrees (the hard coat layer is The test involves folding the product 100,000 times to ensure there are no cracks or damage to the bent parts. The optical films according to the examples and the comparative examples were also examined for the occurrence of breakage. The new sample was then attached to the durability tester in the same manner as above, and the Continuous folding test in which the resin side is folded 180 degrees (hard coat layer is on the outside, resin layer is on the outside) The test involves folding the product so that the innermost part is on the inside 100,000 times, and no cracks or breaks are found in the bent area. The results of the continuous folding test were evaluated according to the following criteria. ○: No cracks or breaks occurred in the bent portion in any of the continuous folding tests. . ×: In any of the continuous folding tests, cracks or breaks occurred at the bent portion.

[0213] <Pencil hardness> Pencil drawing on the surface (surface of the hard coat layer) of the optical film according to the examples and comparative examples The hardness was measured based on JIS K5600-5-4:1999. When measuring the pencil hardness, a load of 1 kg is applied to the pencil and it is moved at a speed of 1 mm / sec. The pencil hardness was determined by the pencil hardness test, which was the hardest point that did not scratch the surface of the optical film. The hardness is considered to be high. When measuring the pencil hardness, multiple pencils with different hardness are used. However, the pencil hardness test was conducted five times for each pencil, and the optical filter was tested under fluorescent light more than four times out of the five times. If no scratches are visible on the surface of the optical film when observed through the optical film, It is judged that the pencil of hardness did not scratch the surface of the optical film.

[0214] The results are shown in Table 1 below. [Table 1]

[0215] The results are described below. In the optical film according to Comparative Example 1, the thickness of the resin layer was The optical film according to Comparative Example 2 was made of a resin. The thickness of the layer is too thin to absorb the shock, and the layer cracks into the soda glass in the impact resistance test A. In addition, the adhesive sheet will not follow the plastic deformation in impact resistance test B. As a result, the amount of depressions on the surface of the hard coat layer was large. In this case, the shear storage modulus G' and shear loss modulus G'' are too small to absorb shock. The soda glass was not able to be collected, and cracks occurred in the impact resistance test A. In the optical film, the shear storage modulus G' is too large and the shear loss modulus G The ´´ is too small to absorb the impact, and the soda glass breaks in impact resistance test A. In addition, the folding property was poor.

[0216] In contrast, in the optical films according to Examples 1 to 6, the thickness of the resin layer and the shear storage elasticity The balance of elastic modulus G´ and shear loss modulus G´´ is good, so the hardness after impact resistance tests A and B is No dents were found on the surface of the hard coat layer, and no cracks were found in the soda glass. In addition, the optical films according to Examples 1 to 6 also showed good results in the continuous folding test. Ta.

[0217] In addition to the above-mentioned continuous folding test, the optical films according to Examples 1 to 6 were subjected to a 3 The samples were cut into rectangles measuring 0 mm x 100 mm and placed in a durability test machine (product name: D The short side (30 mm) of the sample was fixed to the "LDMLH-FS" (Yuasa System Co., Ltd.). As shown in Figure 3(C), the minimum distance between the two opposing sides is 2 The hard coat layer side of the sample is folded 180°. Continued folding test (test in which the hard coat layer is folded on the inside and the resin layer on the outside) ) was repeated 100,000 times, and the bending part was checked for cracks or breaks. In addition, the optical films according to Examples 1 to 6 were prepared in the same manner as above. The new sample was placed in the durability tester and the shortest length of the two opposing sides was measured in the same manner as above. The sample is attached so that the gap is 2 mm, and the resin layer side of the sample is folded 180 degrees. Continued folding test (test in which the hard coat layer is folded on the outside and the resin layer on the inside) ) was repeated 100,000 times, and the bending part was checked for cracks or breaks. Or no fracture occurred.

[0218] In addition, in the optical films according to Examples 1 to 6, a rectangular shape of 30 mm×100 mm was The short side (30 mm) of the sample was cut so that the spacing between the opposing sides of the sample was 3 The optical film was then folded and fixed to the fixing parts arranged in parallel so that the A folding and standing test was carried out in which the product was left in its folded state at 70°C for 240 hours. After the test, the folded state was released by removing the fixing part from one side and the product was left in the folded state at room temperature. After 30 minutes, the opening angle (see Figure 4(B)), which is the angle at which the optical film naturally opens, was measured. The optical films according to Examples 1 to 4 have an opening angle of 100° or more, and the optical films according to Example 5 have an opening angle of 100° or more. This result indicates that the shear storage modulus G' is 800M It was confirmed that the restoration property is good when the pressure is less than Pa. The two methods are folding the sheet so that the hard coat layer is on the inside and folding the sheet so that the hard coat layer is on the outside. Static folding tests were conducted in both the folded and unfolded cases, and the one with the smaller angle was adopted.

[0219] In addition, the first hard coat layer and the second hard coat layer of the optical films according to Examples 1 to 6 were The Martens hardness of the first hard coat layer was measured using the Martens hardness of the first hard coat layer. The hardness of the first hard coat layer was 830 MPa, and the Martens hardness of the second hard coat layer was 500 MPa. The Martens hardness was measured using the HYSITRON TI950 Tri The first hard coat layer and the second hard coat layer were measured under the following measurement conditions using the "Indenter" The Berkovich indenter (triangular pyramid) was placed at a distance of 50 The specimen is pressed down to 0 nm, held for a certain period of time to relax the residual stress, and then unloaded. Measure the maximum load, P max (μN) and the area A of the 500 nm deep indentation (nm 2 ) and P max The Martens hardness was calculated by measuring at 10 points. The arithmetic mean of the values ​​was calculated. (Measurement conditions) ·Loading speed: 10nm / sec ·Holding time: 5 seconds ·Loading and unloading speed: 10nm / sec ·Measurement temperature: 25℃

[0220] In addition, the surfaces of the optical films according to Examples 1 to 6 (surfaces of the hard coat layers) were Steel wool #000 (product name: "BON STAR", Japan Steel Wool Co., Ltd.) (manufactured by ) at 1kg / cm 2 The load is applied and the friction is repeated 10 times at a speed of 50 mm / sec. After that, the surface of the optical film was visually inspected for scratches, and no scratches were found. There wasn't. [Explanation of symbols]

[0221] 10, 40...Optical film 10A, 12A, 40A…Surface 11...Resin substrate 11A...First side 11B...Second side 12...Hard coat layer 12A…First hard coat layer 12B: Second hard coat layer 13...Resin layer 50...Image display device 53...Display panel 56…adhesive layer

Claims

1. A foldable, light-transmitting optical film for use in an image display device, comprising: A resin substrate; a hard coat layer provided on the first surface side of the resin substrate; a resin layer having a film thickness of 50 μm or more and 300 μm or less, provided on a second surface side of the resin substrate opposite to the first surface, the optical film has a shear storage modulus G' of 400 MPa or more and 1200 MPa or less at 25°C in a frequency range of 500 Hz or more and 1000 Hz or less, the optical film has a shear loss modulus G" of 20 MPa or more and 150 MPa or less at 25°C in a frequency range of 500 Hz or more and 1000 Hz or less, an optical film having a shear loss tangent tanδ, which is a ratio of the shear loss modulus G″ to the shear storage modulus G′, of 0.10 to 0.

15.

2. 2. The optical film according to claim 1, wherein the optical film does not crack or break when a test in which the optical film is folded 180 degrees so that the distance between opposing sides of the optical film is 30 mm is repeated 100,000 times.

3. 3. The optical film according to claim 1, wherein the resin substrate is a substrate made of a polyimide resin, a polyamide resin, or a mixture thereof.

4. A foldable image display device, A display panel; the optical film according to claim 1 , which is disposed closer to a viewer than the display panel; The image display device, wherein the hard coat layer of the optical film is located closer to a viewer than the resin substrate.

5. The image display device according to claim 4 , further comprising an adhesive layer disposed between the optical film and the display panel.

6. 6. The image display device according to claim 4, wherein the display panel is an organic light-emitting diode panel.

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