Optical laminates and articles

Abstract

An object of the present invention is to provide an optical laminate and an article in which color change before and after sliding is hardly noticeable visually. 【Solution】This optical laminate has a transparent base material, a hard coat layer, an adhesion layer, an optical functional layer, and an antifouling layer laminated in this order. When a 500-reciprocation sliding test is performed with a load of 250 g using a sliding tool having a Shore D hardness of 40 and a diameter of 0.8 mm, L before and after sliding at the sliding position * a * b * b in the color system * value change Δb * has an absolute value of 1.9 or less, and L of reflected light when incident at an incident angle of 5° * a * b * b in the color system * value, and L of reflected light when incident at an incident angle of 45° * a * b * b in the color system * value, and the change Δb between * has an absolute value of 6.0 or less.

Description

[Technical Field]

[0001] This invention relates to optical laminates and articles. [Background technology]

[0002] For example, an anti-reflective optical laminate may be provided on the surface of flat panel displays (FPDs), touch panels, solar cells, etc. Since the image is viewed through the optical laminate, it is required that the optical laminate does not adversely affect visibility. Furthermore, with the increasing use of touch panels in various operating devices, improved scratch resistance is also required for the optical laminate.

[0003] For example, Patent Document 1 describes a in the CIE-Lab color system * Value and b * It is stated that color unevenness on the display can be reduced by making the difference in values ​​2 or more.

[0004] For example, Patent Document 2 describes that pen-resistant sliding properties can be improved by optimizing the composition of the outermost low-refractive-index layer.

[0005] For example, Patent Document 3 describes an article having an anti-reflective coating that can reduce the visibility of surface defects caused by scratches and fingerprints.

[0006] For example, Patent Document 4 describes an article having a scratch-resistant layer and exhibiting excellent durability and scratch resistance. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2019-28364 [Patent Document 2] Japanese Patent Publication No. 2004-86196 [Patent Document 3] Japanese Patent Publication No. 2020-126278 [Patent Document 4] Patent No. 6761348 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the case of pen-touch type touch panels, the pen slides across the surface of the optical laminate. The marks left by the pen sliding may reduce visibility.

[0009] This invention has been made in view of the above problems, and aims to provide an optical laminate and an article in which the color change before and after sliding is not easily noticeable to the naked eye. [Means for solving the problem]

[0010] To solve the above problems, the present invention provides the following means.

[0011] (1) The optical laminate according to the first embodiment is made up of a transparent substrate, a hard coat layer, an adhesion layer, an optical functional layer and an antifouling layer laminated in order, and when a sliding test was performed with a Shore D hardness of 40 and a diameter of 0.8 mm under a load of 250 g for 500 reciprocations, the L of the sliding point before and after sliding was * a * b * b in the color system * Change in value Δb * The absolute value of the value is 1.9 or less.

[0012] (2) In the optical laminate according to the above embodiment, the optical functional layer comprises, in order from the side closest to the adhesion layer, a first high refractive index layer, a first low refractive index layer, a second high refractive index layer, and a second low refractive index layer, wherein each of the first high refractive index layer and the second high refractive index layer has a refractive index higher than each of the first low refractive index layer and the second low refractive index layer, the physical film thickness of the first high refractive index layer is 10 nm or more and 20 nm or less, the physical film thickness of the first low refractive index layer is 2 nm or more and 15 nm or less, and the physical film thickness of the second low refractive index layer is 70 nm or more and 85 nm or less.

[0013] (3) In the optical laminate according to the above embodiment, the optical functional layer comprises, in order from the side closest to the adhesion layer, a first high refractive index layer, a first low refractive index layer, a second high refractive index layer, and a second low refractive index layer, wherein each of the first high refractive index layer and the second high refractive index layer has a higher refractive index than each of the first low refractive index layer and the second low refractive index layer, the optical film thickness of the first high refractive index layer is 20 nm or more and 48.8 nm or less, the optical film thickness of the first low refractive index layer is 2.9 nm or more and 21.9 nm or less, and the optical film thickness of the second low refractive index layer may be 102 nm or more and 124.1 nm or less.

[0014] (4) In the optical laminate according to the above embodiment, the total thickness of the physical film thickness of the optical functional layer may be 170 nm or more and 220 nm or less.

[0015] (5) In the optical laminate according to the above embodiment, the total thickness of the optical film thickness of the optical functional layer may be 320 nm or more and 410 nm or less.

[0016] (6) In the optical laminate according to the above embodiment, the physical thickness of the antifouling layer may be 2 nm or more and 10 nm or less.

[0017] (7) In the optical laminate according to the above embodiment, the optical functional layer may be a sputtered film.

[0018] (8) In the optical laminate according to the above embodiment, the antifouling layer may be a vapor-deposited film.

[0019] (9) In the optical laminate according to the above embodiment, the antifouling layer may contain a fluorine compound.

[0020] (10) The article relating to the second embodiment comprises an optical laminate relating to the above embodiment. [Effects of the Invention]

[0021] The optical laminate and article according to the above embodiment show little visible color change before and after sliding. [Brief explanation of the drawing]

[0022] [Figure 1] It is a cross-sectional view of an example of the optical layered body according to the first embodiment. MODE FOR CARRYING OUT THE INVENTION

[0023] Hereinafter, the present embodiment will be described in detail with appropriate reference to the drawings. In the drawings used in the following description, characteristic portions may be enlarged for convenience in order to make the features easier to understand, and the dimensional ratios and the like of respective components may differ from actual ones. Materials, dimensions, and the like exemplified in the following description are merely examples, the present invention is not limited thereto, and can be implemented with appropriate modifications within the scope that achieves the effects of the present invention.

[0024] "Optical Layered Body" When a 500-reciprocation sliding test is performed on the optical layered body 10 according to the present embodiment with a load of 250 g using a sliding tool having a Shore D hardness of 40 and a diameter of 0.8 mm, the L of the sliding portion before and after sliding * a * b * b in the color system * value change amount Δb * has an absolute value of 1.9 or less.

[0025] The sliding test is carried out according to the following procedure. First, the optical layered body 10 is bonded to a 1 mm-thick glass sheet using a transparent adhesive sheet (manufactured by Lintec Corporation) such that the antifouling layer 5 of the optical layered body 10 is located on the surface. Then, a linear sliding test is performed using a sliding tester (manufactured by Imoto Seisakusho Co., Ltd.) with a polyacetal pen (tip shape: 0.8 mmφ, Shore D hardness: 40). The load is 250 gf, the number of sliding movements is 1000 times (500 reciprocations), the reciprocation distance is 50 mm, and the sliding speed is 2 reciprocations per second.

[0026] L * a * b * In the color system, L * represents lightness, a * value and b * value represent chromaticity. a * value and b* The color of a coordinate with a larger absolute value has higher saturation. That is, a * Value and b * The color of a coordinate with a larger absolute value is a more vivid color, * Value and b * The smaller the absolute value of the coordinate's color, the closer the color is to achromatic. +a * The coordinates are the hue in the red direction, and -a * The coordinates are the hue in the green direction, and +b * The coordinates are the hue in the yellow direction, and -b * The coordinates represent the hue in the blue direction. Color measurements are performed using light with wavelengths of 380nm to 780nm from the standard light source D65. L before and after sliding * value, a * value, b * In measuring the values, the angle of incidence of light to the measurement surface was set to 0°.

[0027] L before and after sliding * a * b * b in the color system * Change in value Δb * If the absolute value of is 1.9 or less, the sliding marks are difficult to see after the pen sliding test. The parameter representing chromaticity is a, as described above. * Value and b * There are two values, but the one that has the greatest impact on visibility before and after sliding is b. * It was the value b. * Change in value Δb * The smaller the change in the absolute value of b, the smaller the impact on visibility. * Change in value Δb * The absolute value of is preferably 1.7 or less, and more preferably 1.3 or less.

[0028] L before and after sliding * a * b * a in color system * Change in value Δa * The absolute value of is preferably 3.8 or less, more preferably 2.8 or less, and even more preferably 2.4 or less. Change Δa *The smaller the value, the less likely it is to cause a decrease in visibility due to sliding. Note that a before and after sliding * Change in value Δa * is, b * Change in value Δb * The impact on visibility is smaller than that of the absolute value.

[0029] Furthermore, the color difference ΔE before and after sliding of the optical laminate 10. * ab is, for example, 3.4 or less, preferably 3.2 or less, more preferably 2.9 or less, and even more preferably 2.8 or less. Color difference ΔE before and after sliding * ab is ΔE * ab=(ΔL *2 +Δa *2 +Δb *2 ) 1 / 2 It is represented as follows: Here, ΔL * ΔL is the amount of change in brightness before and after sliding. * And Δa * a before and after sliding * This is the amount of change in value, Δb * b before and after sliding * This represents the change in value.

[0030] Furthermore, the optical laminate 10 according to this embodiment preferably reflects the L of the reflected light when incident at an incident angle of 5°. * a * b * b in the color system * The value and the L of the reflected light when incident at an angle of incidence of 45°. * a * b * b in the color system * The change between the value and Δb * The absolute value of is 6.0 or less. Color measurement is performed using light with wavelengths of 380nm to 780nm from the standard light source D65.

[0031] As mentioned above, +a * The coordinates are the hue in the red direction, and -a * The coordinates are the hue in the green direction, and +b * The coordinates are the hue in the yellow direction, and -b *coordinate is the hue in the blue direction. On the other hand, the center of the wavelength of visible light, which has a high influence on visibility, is near 565 nm, which is in L * a * b * *a*b color system, it is located at -a * and +b * coordinates, which is a hue in a coordinate region consisting of the yellow direction and the green direction. In order to suppress visible hue change (color unevenness) caused by changes in incident angle, the optical layered body of the present embodiment suppresses hue change in the coordinate direction consisting of the easily visible yellow direction and green direction, thereby making color unevenness difficult to visually recognize.

[0032] The optical layered body according to the present embodiment satisfies that the absolute value of Δb * a * b * value of b in the L*a*b* color system of reflected light when incident at an incident angle of 5° and the b * value of b in the L*a*b* color system of reflected light when incident at an incident angle of 45° is 6.0 or less. * a * b * value of b in the L*a*b* * between the valuesΔb * the absolute value of which is 6.0 or less.

[0033] Further, in the optical layered body according to the present embodiment, the b * a * b * value of b in the L*a*b* * of reflected light when incident at an incident angle of 5° and the b * a * b * value of b in the L*a*b* * value of reflected light when incident at an incident angle of 45° each preferably satisfy -20≦b * ≦10, and more preferably satisfy -20≦b * ≦0.

[0034] Further, in the optical layered body according to the present embodiment, the a * a * b * value of a in the L*a*b* * of reflected light when incident at an incident angle of 5° and the L * a * b* a in color system * Each value is preferably -10 ≤ a * Satisfying ≤20, and comfort - 3 ≤ a * It satisfies ≤ 6.

[0035] Furthermore, when incident at an angle of incidence of 5°, the reflected light L * a * b * a in color system * The value and the L of the reflected light when incident at an angle of incidence of 45°. * a * b * a in color system * Change Δa between the value and the value * It is preferable that the absolute value of is 10 or less, as this makes color unevenness caused by changing the viewing angle less noticeable. Also, at this time, the a* value at an incident angle of 45° is used to determine the a at an incident angle of 5°. * It is preferable that the difference obtained by subtracting the values ​​is positive.

[0036] b * The value has a significant impact on visual sensitivity and is likely to affect the hue of an object. The b value is associated with differences in viewing angle. * Change in value Δb * If the viewing angle is small, changes in hue caused by changes in viewing angle become less noticeable, and color unevenness becomes less visible.

[0037] b * The value is -15 ≤ b * Satisfying ≤10, preferably -15 ≤ b * Since ≤ 0, a * Changes in value become harder to see. In particular, because b ≤ 0, a * Changes in values ​​become harder to see.

[0038] a * The value is -10 ≤ a * Satisfying ≤20, preferably -3 ≤ a * By satisfying the condition ≤ 6, the influence of green-oriented colors, which make color unevenness more visible, can be avoided.

[0039] b * Change in value Δb * In addition to a * Change in value △a * If the size is small, color unevenness caused by changing the viewing angle becomes even more difficult to see.

[0040] Furthermore, the color difference ΔE due to the difference in the angle of incidence of light in the optical laminate 10. * ab is, for example, 19.4 or less, preferably 15.2 or less, more preferably 13.6 or less, and even more preferably 10 or less. Color difference ΔE due to difference in angle of incidence of light * ab is the L of the reflected light when incident at an angle of incidence of 5°. * a * b * Value and the L of the reflected light when incident at an angle of incidence of 45° * a * b * Value and ΔE * ab=(ΔL *2 +Δa *2 +Δb *2 ) 1 / 2 It can be calculated as follows: Here, ΔL * ΔL is the amount of change in brightness due to the difference in the angle of incidence of light. * And Δa * a is due to the difference in the angle of incidence of light * This is the amount of change in value, Δb * b is due to the difference in the angle of incidence of light * This represents the change in value.

[0041] Figure 1 is a cross-sectional view of an example of an optical laminate 10 according to the first embodiment. The optical laminate 10 is constructed by sequentially laminating a transparent substrate 1, a hard coat layer 2, an adhesion layer 3, an optical functional layer 4, and an anti-fouling layer 5.

[0042] (Transparent base material) The transparent substrate 1 is made of a transparent material that can transmit light in the visible light range. The transparent substrate 1 is, for example, a plastic film. The constituent materials of the plastic film are, for example, polyester resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, and polyphenylene sulfide resins. The transparent substrate 1 is an inorganic substrate and may also be a glass film.

[0043] The constituent material of the transparent substrate 1 is preferably a polyester resin, acetate resin, polycarbonate resin, or polyolefin resin. The transparent substrate 1 is preferably, for example, a polyethylene terephthalate (PET) substrate or a triacetylcellulose (TAC) substrate.

[0044] In this invention, "transparent material" refers to a material with a light transmittance of 80% or more in the wavelength range used, as long as it does not impair the effects of the present invention. In this embodiment, "(meth)acrylic" means methacrylic and acrylic.

[0045] The transparent substrate 1 may contain reinforcing materials, provided that they do not significantly impair the optical properties. Examples of reinforcing materials include cellulose nanofibers and nanosilica.

[0046] The transparent substrate 1 may be a film to which optical and / or physical functions are imparted. Examples of films with optical and / or physical functions include polarizing plates, phase difference compensation films, heat shielding films, transparent conductive films, brightness-enhancing films, barrier-enhancing films, and lens sheets. These films may also be to which antistatic functions are imparted.

[0047] The thickness of the transparent substrate 1 is not particularly limited, but is, for example, 25 μm or more, preferably 40 μm or more. The thickness of the transparent substrate 1 is the physical film thickness. When the thickness of the transparent substrate 1 is 25 μm or more, the rigidity of the substrate itself is ensured, and wrinkles are less likely to occur even when stress is applied to the optical laminate 10. Also, when the thickness of the transparent substrate 1 is 25 μm or more, wrinkles are less likely to occur even when the hard coat layer 2 is continuously formed on the transparent substrate 1, reducing manufacturing concerns. When the thickness of the transparent substrate 1 is 25 μm or more, the optical laminate 10 is less likely to curl during manufacturing and is easier to handle.

[0048] The thickness of the transparent substrate 1 is preferably 1 mm or less, more preferably 500 μm or less, and particularly preferably 300 μm or less. When the thickness of the transparent substrate 1 is 1 mm or less, the substantial optical transparency of the transparent substrate 1 can be ensured. Furthermore, when the thickness of the transparent substrate 1 is 1 mm or less, a film can be formed on the transparent substrate 1 using either a single-wafer method or a roll-to-roll method. In particular, when the thickness of the transparent substrate 1 is 300 μm or less, the length of the transparent substrate 1 that can be fed into the roll at one time can be increased when manufacturing the optical laminate 10 using the roll-to-roll method. For this reason, when the thickness of the transparent substrate 1 is 300 μm or less, productivity is excellent when continuously producing the optical laminate 10 using the roll-to-roll method. Furthermore, when the thickness of the transparent substrate 1 is 300 μm or less, a high-quality optical laminate 10 is obtained, which is therefore preferable.

[0049] The transparent substrate 1 may have its surface pre-treated with etching treatments such as sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, and / or undercoating treatments. These treatments improve the adhesion of the hard coat layer 2 formed on the transparent substrate 1. Furthermore, before forming the hard coat layer 2 on the transparent substrate 1, the surface of the transparent substrate 1 may be cleaned and dust-free by solvent cleaning, ultrasonic cleaning, etc., as needed.

[0050] (Hard coat layer) The hard coat layer 2 is not particularly limited, and known materials can be used. The hard coat layer 2 may, for example, include a binder resin and a filler. In addition, the hard coat layer 2 may also include a leveling agent.

[0051] The binder resin is preferably transparent and may be, for example, an ionizing radiation-curing resin that hardens with ultraviolet light or electron beams, a thermoplastic resin, or a thermosetting resin.

[0052] Examples of ionizing radiation-curable resins used as binder resins include ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, methylstyrene, and N-vinylpyrrolidone. Ionizing radiation-curable resins may also be compounds having two or more unsaturated bonds. Examples of ionizing radiation-curable resins having two or more unsaturated bonds include trimethylolpropane tri(meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and dipentaerythritol These include polyfunctional compounds such as lithol penta(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, isocyanuric acid tri(meth)acrylate, isocyanuric acid di(meth)acrylate, polyester tri(meth)acrylate, polyester di(meth)acrylate, bisphenol di(meth)acrylate, diglycerin tetra(meth)acrylate, adamantyl di(meth)acrylate, isobolonyl di(meth)acrylate, dicyclopentane di(meth)acrylate, tricyclodecane di(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate. Among these, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), and pentaerythritol tetraacrylate (PETTA) are suitably used as binder resins. Note that "(meth)acrylate" refers to methacrylate and acrylate. Furthermore, the ionizing radiation-curable resin may be one of the above-mentioned compounds modified with PO (propylene oxide), EO (ethylene oxide), CL (caprolactone), etc. An acrylic-based ultraviolet-curable resin composition is preferred for the ionizing radiation-curable resin.

[0053] Examples of thermoplastic resins used as binder resins include styrene resins, (meth)acrylic resins, vinyl acetate resins, vinyl ether resins, halogen-containing resins, alicyclic olefin resins, polycarbonate resins, polyester resins, polyamide resins, cellulose derivatives, silicone resins, and rubber or elastomers. The above thermoplastic resins are amorphous and soluble in organic solvents (especially common solvents capable of dissolving multiple polymers and curable compounds). In particular, from the viewpoint of transparency and weather resistance, the binder resin is preferably a styrene resin, (meth)acrylic resin, alicyclic olefin resin, polyester resin, cellulose derivative (cellulose esters, etc.).

[0054] The thermosetting resin used as the binder resin may be, for example, phenolic resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, amino alkyd resin, melamine-urea cocondensation resin, silicon resin, polysiloxane resin (including so-called silsesquioxanes such as cage-like or ladder-like structures), etc.

[0055] The hard coat layer 2 may contain an organic resin and an inorganic material, or it may be an organic-inorganic hybrid material. One example is one formed by the sol-gel method. Examples of inorganic materials include silica, alumina, zirconia, and titania. An example of an organic material is acrylic resin.

[0056] The filler may consist of organic materials, inorganic materials, or a combination of both. The filler included in the hard coat layer 2 can be selected from a variety of options depending on the application of the optical laminate 10, considering factors such as anti-glare properties, adhesion to the optical functional layer 4 (described later), and anti-blocking properties. Specifically, known fillers such as silica (silicon oxide) particles, alumina (aluminum oxide) particles, and organic fine particles can be used.

[0057] When the filler is silica particles and / or alumina particles, the average particle size of the filler is, for example, 800 nm or less, preferably 100 nm or less, and more preferably 40 nm to 70 nm. When the filler is organic fine particles, the average particle size of the organic fine particles is, for example, 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less.

[0058] The thickness of the hard coat layer 2 is preferably 0.5 μm or more, and more preferably 1 μm or more. The thickness of the hard coat layer 2 is preferably 100 μm or less. The thickness of the hard coat layer 2 is the physical film thickness. The hard coat layer 2 may consist of a single layer or may consist of multiple layers laminated together.

[0059] (Intense layer) The adhesion layer 3 is located between the hard coat layer 2 and the optical functional layer 4. The adhesion layer 3 improves the adhesion between the hard coat layer 2 and the optical functional layer 4.

[0060] The adhesion layer 3 consists of one or more of the following: metals such as silicon, nickel, chromium, tin, gold, silver, platinum, zinc, titanium, tungsten, aluminum, zirconium, palladium, and indium; alloys of these metals; or oxides, fluorides, sulfides, or nitrides of these metals.

[0061] The adhesion layer 3 may contain an inorganic oxide of a non-stoichiometric composition. The adhesion layer 3 may also be, for example, a metal oxide in an oxygen-deficient state, such as SiO2. x The main component may be (Si oxide). The adhesion layer 3 may consist only of Si oxide, or it may contain other elements in a range of 50% by mass or less, preferably 10% by mass or less, in addition to Si oxide. As other elements, Na may be included to improve the durability of the adhesion layer 3, or one or more elements selected from Zr, Al, and N may be included to improve the hardness of the adhesion layer 3.

[0062] The thickness of the adhesion layer 3 is preferably, for example, 1 nm to 10 nm, and more preferably 1 nm to 5 nm. The thickness of the adhesion layer 3 is the physical film thickness. When the thickness of the adhesion layer 3 is within the above range, the adhesion between the optical functional layer 4 and the hard coat layer 2 is improved.

[0063] (optical functional layer) The optical functional layer 4 is the layer that exhibits optical functions. Optical functions are functions that control the properties of light, such as reflection, transmission, and refraction, and include, for example, anti-reflective functions, selective reflection functions, anti-glare functions, and lens functions.

[0064] The optical functional layer 4 is, for example, a laminated film in which high refractive index layers and low refractive index layers are alternately stacked from the adhesion layer 3 side. The high refractive index layers have a higher refractive index than the low refractive index layers. The refractive index of each high refractive index layer may be the same or different. The refractive index of each low refractive index layer may be the same or different.

[0065] The total number of layers of low-refractive-index and high-refractive-index layers in the optical functional layer 4 is not particularly limited. For example, as shown in Figure 1, the number of layers of each layer may be 4, 3 or less, or 5 or more. The total number of layers of low-refractive-index and high-refractive-index layers in the optical functional layer 4 is preferably 4 to 10, more preferably 4 to 6, and most preferably 4. When the optical functional layer 4 has 4 layers, the productivity is superior compared to when the number of layers is 5 or more, because the number of layers is small and the thickness is thin. Also, when the optical functional layer 4 has 4 layers, the anti-reflective properties are higher compared to when the number of layers is 3 or less, and the hue of the reflected light can be made even closer to neutral (achromatic).

[0066] The optical functional layer 4 exhibits an anti-reflective function by causing interference between reflected light reflected at each interface of the laminate, in which high-refractive-index layers and low-refractive-index layers are alternately stacked, and by diffusing light incident from the anti-fouling layer 5 side.

[0067] The following explanation will use the example of a laminate in which the optical functional layer 4 is a laminate in which four layers are stacked in order from the side closest to the adhesion layer 3: a first high refractive index layer 41a, a first low refractive index layer 41b, a second high refractive index layer 42a, and a second low refractive index layer 42b. The refractive index of the first high refractive index layer 41a and the second high refractive index layer 42a is higher than that of the first low refractive index layer 41b and the second low refractive index layer 42b, respectively.

[0068] The refractive indices of the first high refractive index layer 41a and the second high refractive index layer 42a are, for example, 2.00 or more and 2.60 or less, preferably 2.10 or more and 2.45 or less. The refractive indices of the first high refractive index layer 41a and the second high refractive index layer 42a may be the same or different.

[0069] Examples of materials for the first high refractive index layer 41a and the second high refractive index layer 42a include niobium pentoxide (Nb2O5, refractive index 2.33), titanium oxide (TiO2, refractive index 2.33-2.55), tungsten oxide (WO3, refractive index 2.2), cerium oxide (CeO2, refractive index 2.2), tantalum pentoxide (Ta2O5, refractive index 2.16), zinc oxide (ZnO, refractive index 2.1), indium tin oxide (ITO, refractive index 2.06), and zirconium oxide (ZrO2, refractive index 2.2). The first high refractive index layer 41a and the second high refractive index layer 42a are preferably made of niobium pentoxide. The materials constituting the first high refractive index layer 41a and the second high refractive index layer 42a may be the same or different.

[0070] The refractive indices of the first low refractive index layer 41b and the second low refractive index layer 42b are, for example, 1.20 or more and 1.60 or less, preferably 1.30 or more and 1.50 or less. The refractive indices of the first low refractive index layer 41b and the second low refractive index layer 42b may be the same or different.

[0071] The first low refractive index layer 41b and the second low refractive index layer 42b contain, for example, an oxide of Si. The first low refractive index layer 41b and the second low refractive index layer 42b are layers mainly composed of, for example, SiO2 (an oxide of Si). Oxides of Si are readily available and cost-effective. The SiO2 monolayer film is colorless and transparent. In this embodiment, the main component is the component that accounts for 50% or more by mass of the components contained in the layer. The refractive indices of the first low refractive index layer 41b and the second low refractive index layer 42b may be the same or different.

[0072] The first low refractive index layer 41b and the second low refractive index layer 42b may contain less than 50% by mass of other elements when Si oxide is the main component. The content of elements other than Si oxide is preferably 10% or less. Examples of other elements are Na, Zr, Al, and N. Na enhances the durability of the first low refractive index layer 41b and the second low refractive index layer 42b. Zr, Al, and N increase the hardness and alkali resistance of the first low refractive index layer 41b and the second low refractive index layer 42b.

[0073] The physical film thickness of the first high refractive index layer 41a is, for example, 10 nm to 20 nm. Preferably, the physical film thickness of the first high refractive index layer 41a is 10 nm to 17 nm. The optical film thickness of the first high refractive index layer 41a is, for example, 20 nm to 48.8 nm. Preferably, the optical film thickness of the first high refractive index layer 41a is 23.8 nm to 44.3 nm. The optical film thickness is the physical film thickness multiplied by the refractive index of the layer.

[0074] The physical film thickness of the first low refractive index layer 41b is, for example, 2 nm to 15 nm. The physical film thickness of the first low refractive index layer 41b is preferably 4 nm to 9 nm, and more preferably 7 nm to 9 nm. The optical film thickness of the first low refractive index layer 41b is, for example, 2.9 nm to 21.9 nm. The optical film thickness of the first low refractive index layer 41b is preferably 5.8 nm to 13.7 nm, and more preferably 10.22 nm to 13.72 nm.

[0075] The physical film thickness of the second high refractive index layer 42a is, for example, 30 nm to 110 nm. Preferably, the physical film thickness of the second high refractive index layer 42a is 74 nm to 102 nm. The optical film thickness of the second high refractive index layer 42a is, for example, 60 nm to 277.2 nm. Preferably, the optical film thickness of the second high refractive index layer 42a is 172.4 nm to 226.8 nm, and more preferably 172.4 nm to 217.9 nm.

[0076] The physical film thickness of the second low refractive index layer 42b is, for example, 70 nm to 85 nm. Preferably, the physical film thickness of the second low refractive index layer 42b is 73 nm to 81 nm. The optical film thickness of the second low refractive index layer 42b is, for example, 102 nm to 124.1 nm. Preferably, the optical film thickness of the second low refractive index layer 42b is 106.6 nm to 118.3 nm.

[0077] By keeping the film thickness of each of the first high refractive index layer 41a, the first low refractive index layer 41b, the second high refractive index layer 42a, and the second low refractive index layer 42b within a specified range, the L of the reflected light from the surface is reduced. * a * b * b in the color system * This makes it possible to realize an optical laminate 10 in which the value does not easily fluctuate in sliding tests. At this time, the film thickness of the first low refractive index layer 41b is the thinnest among all the layers of the optical functional layer 4.

[0078] The total physical thickness of the optical functional layer 4 is, for example, 170 nm to 220 nm, preferably 180 nm to 210 nm, and more preferably 189 nm to 198 nm. The total optical thickness of the optical functional layer 4 is, for example, 320 nm to 410 nm, preferably 341.4 nm to 399.0 nm, and more preferably 362.8 nm to 386.8 nm. By having the total thickness of the optical functional layer 4 within a predetermined range, the hue of the reflected light can be brought closer to neutral, and production can be carried out efficiently.

[0079] Each layer of the optical functional layer 4 is, for example, a sputtered film. Sputtered films are denser than films formed using general vacuum deposition or coating methods. For example, the water vapor permeability of the optical functional layer 4 is 1.0 g / m². 2 The result is less than / day. The dense sputtering film has low water vapor transmission. The sputtering film is dense and less likely to leave friction marks. For example, even if a part of the anti-fouling layer 5 peels off due to pen friction, the dense optical functional layer 4 makes it difficult for pen friction marks to be left.

[0080] Among the layers forming the optical functional layer 4, a low refractive index layer 4b is arranged on the side facing the antifouling layer 5. When the low refractive index layer 4b of the optical functional layer 4 is in contact with the antifouling layer 5, the anti-reflective performance of the optical functional layer 4 is improved.

[0081] (Anti-fouling layer) The anti-fouling layer 5 is located on the surface of the optical functional layer 4 opposite to the surface in contact with the adhesion layer 3. The anti-fouling layer 5 is located on the outermost surface of the optical functional layer 4. The anti-fouling layer 5 prevents contamination of the optical functional layer 4. In addition, the anti-fouling layer 5 suppresses wear and tear of the optical functional layer 4 caused by pen friction when applied to touch panels, etc.

[0082] The antifouling layer 5 is, for example, a vapor-deposited film formed by depositing an antifouling material. The antifouling layer 5 is formed, for example, by vacuum-depositing a fluorine-based compound as an antifouling material onto one surface of the second low refractive index layer 42b that constitutes the optical functional layer 4. When the antifouling layer 5 contains a fluorine-based compound, it makes the sliding motion smoother when using a pen, and at the same time, the pen sliding resistance of the optical laminate 10 is further improved.

[0083] The fluorine-based compounds contained in the antifouling layer 5 are, for example, fluorine-based organic compounds. These fluorine-based organic compounds are, for example, compounds consisting of a fluorine-modified organic group and a reactive silyl group (e.g., alkoxysilane). Examples of commercially available products that can be used in the antifouling layer 5 include Optool DSX (manufactured by Daikin Corporation) and the KY-100 series (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0084] When a compound consisting of a fluorine-modified organic group and a reactive silyl group (e.g., alkoxysilane) is used in the antifouling layer 5, and SiO2 is used in the second low refractive index layer 42b of the optical functional layer 4, a siloxane bond is formed between the silanol group, which is the backbone of the fluorine-based organic compound, and SiO2. The siloxane bond enhances the adhesion between the optical functional layer 4 and the antifouling layer 5.

[0085] The thickness of the antifouling layer 5 is, for example, 1 nm to 20 nm, preferably 3 nm to 10 nm. The thickness of the antifouling layer is the physical film thickness. If the thickness of the antifouling layer 5 is 1 nm or more, sufficient abrasion resistance can be ensured when the optical laminate 10 is applied to touch panel applications, etc. Also, if the thickness of the antifouling layer 5 is 20 nm or less, the time required for deposition is shortened, and manufacturing can be done efficiently.

[0086] The antifouling layer 5 may contain additives such as light stabilizers, ultraviolet absorbers, colorants, antistatic agents, lubricants, leveling agents, defoamers, antioxidants, flame retardants, infrared absorbers, and surfactants, as needed.

[0087] The antifouling layer 5 formed by vapor deposition is strongly bonded to the optical functional layer 4, has few voids and is dense. Therefore, the antifouling layer 5 formed by vapor deposition exhibits different properties from antifouling layers 5 formed by other methods such as coating with antifouling materials. The antifouling layer 5 formed by vapor deposition is resistant to wear.

[0088] Next, a method for manufacturing the optical laminate according to this embodiment will be described. First, a transparent substrate 1 is prepared. The transparent substrate can be obtained, for example, by purchasing a commercially available product.

[0089] Next, a hard coat layer 2 is formed on one surface of the transparent substrate 1. A slurry containing the material that will become the hard coat layer 2 is applied to the transparent substrate 1, and the material that will become the hard coat layer 2 is cured by a known method to obtain the hard coat layer 2. Before forming the hard coat layer 2 on the transparent substrate 1, the surface may be cleaned as needed. Examples of methods for cleaning the surface of the transparent substrate 1 include solvent cleaning and ultrasonic cleaning. Cleaning the transparent substrate 1 is preferable because it removes dust from the surface of the transparent substrate 1 and cleans the surface. Alternatively, a commercially available transparent substrate 1 with a hard coat layer 2 already formed on it may be purchased.

[0090] Next, an adhesion layer 3 is formed on the hard coat layer 2. The method for manufacturing the adhesion layer 3 is not particularly limited and can be manufactured using known manufacturing methods. The adhesion layer 3 can be formed, for example, by sputtering.

[0091] Next, an optical functional layer 4 is formed on the hard coat layer 2. The optical functional layer 4 is formed, for example, by sequentially depositing a first high refractive index layer 41a, a first low refractive index layer 41b, a second high refractive index layer 42a, and a second low refractive index layer 42b on the adhesion layer 3. Each of the first high refractive index layer 41a, the first low refractive index layer 41b, the second high refractive index layer 42a, and the second low refractive index layer 42b is fabricated, for example, using a sputtering method. Examples of power supply methods for the sputtering method include DC (direct current), RF (radio frequency), and MF (mid frequency). When the optical functional layer is made of an oxide film, sputtering is not possible with DC, and productivity is poor with RF. For this reason, when sputtering an oxide film, a dual magnetron sputtering apparatus using an MF power supply is preferred as the sputtering apparatus. The sputtering frequency is preferably 20 kHz to 60 kHz. The vacuum level during sputtering is, for example, 1.0 Pa or less. Furthermore, when forming the optical functional layer 4 using a roll-to-roll method, the transport speed (line speed) should be set to, for example, 0.5 m / min or more and 20 m / min or less. When the optical functional layer 4 is formed under these conditions, each layer of the optical functional layer 4 becomes dense.

[0092] Next, an antifouling layer 5 is formed on the second low refractive index layer 42b of the optical functional layer 4. It is preferable to perform plasma treatment on the surface of the optical functional layer 4 before forming the antifouling layer 5. Modifying the surface of the second low refractive index layer 42 by plasma treatment improves the adhesion between the optical functional layer 4 and the antifouling layer 5. The cumulative force during plasma treatment is 130 W·min / m 2 More than 2000W min / m 2 The following is preferable. Being within this range improves sliding resistance.

[0093] The antifouling layer 5 is formed, for example, by vapor deposition. Vapor deposition is performed by heating the material that will become the antifouling layer 5 to its vapor pressure temperature. The vacuum level during vapor deposition is, for example, 1.0 Pa or less. When the antifouling layer 5 is formed under these conditions, the antifouling layer 5 becomes dense and resistant to wear.

[0094] The deposition of the adhesion layer 3, the optical functional layer 4, and the anti-fouling layer 5 is preferably carried out using a roll-to-roll method under reduced pressure. By following the above procedure, the optical laminate 10 can be manufactured.

[0095] The optical laminate 10 according to the first embodiment has L before and after sliding * a * b * b in the color system * Change in value Δb * The absolute value of the value is less than or equal to the predetermined value. b before and after sliding * Change in value Δb * When the value is small, although the exact reason is unclear, it is difficult to visually confirm the sliding marks after the sliding test.

[0096] The present invention is not limited to the embodiments described above, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims.

[0097] The optical laminate 10 may have layers other than the transparent substrate 1, hard coat layer 2, adhesion layer 3, optical functional layer 4, and anti-fouling layer 5. The optical laminate 10 may also have various layers on the surface of the transparent substrate 1 facing the surface on which the optical functional layer 4 etc. is formed, as needed. For example, an adhesive layer used for bonding with other components may be provided. Alternatively, other optical films may be provided via this adhesive layer. Examples of other optical films include polarizing films, phase difference compensation films, films that function as half-wave plates or quarter-wave plates.

[0098] Furthermore, layers having functions such as anti-reflection, selective reflection, anti-glare, polarization, phase difference compensation, viewing angle compensation or magnification, light guidance, diffusion, brightness enhancement, hue adjustment, and conductivity may be directly formed on the opposing surfaces of the transparent substrate 1. Nano-order uneven structures that exhibit moth-eye or anti-glare functions may be formed on the surface of the optical laminate 10. Micro to millimeter-order geometric shapes such as lenses and prisms may be formed on the surface of the optical laminate 10.

[0099] Furthermore, the optical laminate 10 can be applied to various articles. For example, the optical laminate 10 may be provided on the screen of an image display unit, such as a liquid crystal display panel or an organic EL display panel. This allows, for example, the touch panel display unit of a smartphone or operating device to exhibit high scratch resistance, resulting in an image display device suitable for practical use.

[0100] Furthermore, the optical laminate 10 is not limited to image display devices, but can also be applied to window glass, goggles, light-receiving surfaces of solar cells, smartphone screens and personal computer displays, information input terminals, tablet terminals, AR (augmented reality) devices, VR (virtual reality) devices, electronic display boards, glass table surfaces, amusement machines, operation support devices for aircraft and trains, navigation systems, instrument panels, and the surfaces of optical sensors. [Examples]

[0101] "Example 1" A film made of polyethylene terephthalate (PET) with a thickness of 80 μm was prepared as the transparent substrate 1. Then, a hard coat layer 2 with a physical thickness of 5 μm was formed on the transparent substrate 1. The hard coat layer 2 was formed by applying a coating solution having the composition shown in Table 1 onto the transparent substrate 1 using a bar coater, and curing it by photopolymerization under ultraviolet light.

[0102] [Table 1]

[0103] Next, on the hard coat layer 2, an adhesion layer 3 and an optical functional layer 4 were continuously formed by reactive sputtering using a mixed gas of Ar gas and O2 gas, with a Si target and an Nb target as sputtering targets.

[0104] The adhesion layer 3 has a physical thickness of 3 nm and is made of oxygen-deficient Si oxide (SiO2). x The following films were deposited: Each layer of the optical functional layer 4 consisted of a first high refractive index layer 41a made of Nb2O5, a first low refractive index layer 41b made of SiO2, a second high refractive index layer 42a made of Nb2O5, and a second low refractive index layer 42b made of SiO2, deposited in this order. The physical and optical film thicknesses of each layer are shown in Tables 2 and 3. The adhesion layer 3 and the optical functional layer 4 were fabricated using a roll-to-roll method with a line speed of 2.0 m / min. An MF dual magnetron sputtering apparatus was used as the sputtering apparatus, with a frequency of 40 kHz.

[0105] Next, an antifouling layer 5 was formed on the optical functional layer 4 by vapor deposition at a vapor deposition chamber pressure of 0.01 Pa or less, a vapor deposition temperature of 230°C, and a line speed of 2.0 m / min. The antifouling layer 5 was made of an alkoxysilane compound (KY-1901, manufactured by Shin-Etsu Chemical Co., Ltd.) having a perfluoropolyether group, which is an organic compound containing fluorine. The thickness of the antifouling layer 5 was 5 nm. After that, it was wound into a roll to obtain the optical laminate (anti-reflective film) of Example 1.

[0106] The surface roughness (Ra), reflectance, and pencil hardness of the fabricated optical laminate were measured. Surface roughness (Ra) was measured using an atomic force microscope (AFM). These results are summarized in Tables 4 and 5. Reflectance was determined from the reflectance spectrum using a spectrophotometer (V-770, JASCO Corporation). Pencil hardness was measured according to JIS K5600-5-4.

[0107] A pen sliding test was performed on the surface of the optical laminate. The pen sliding test was carried out according to the following procedure. First, the optical laminate 10 was bonded to a 1 mm thick glass using a transparent adhesive sheet (manufactured by Lintec Corporation) with the anti-fouling layer 5 facing outwards. Then, a linear sliding test was performed using a polyacetal pen (tip shape 0.8 mmφ, Shore D hardness 40) and a sliding test machine (manufactured by Imoto Seisakusho). The load was 250 gf, the number of sliding cycles was 1000 (500 back and forth), the back and forth distance was 50 mm, and the back and forth speed was 2 times per second (1 back and forth).

[0108] The change in chromaticity of reflected light before and after the sliding test was determined as follows. A black PET film with adhesive was laminated to the back side of the glass sample for the pen sliding test, and measurements were taken for both the sample before and after sliding using an Olympus Corporation USPM-RU-W. The incident light was 380 nm to 780 nm wavelength light from a standard light source D65. The angle of incidence of the light was set to 0°. The results are shown in Tables 4 and 5.

[0109] Furthermore, for the obtained optical laminates, the change in chromaticity of the reflected light was determined by changing the angle of incidence of light to the surface of the optical laminate. The change in chromaticity of the reflected light was measured using a spectrophotometer (V-770, manufactured by JASCO Corporation) after attaching the transparent substrate side of the optical laminate to the surface of a black acrylic panel using an acrylic transparent adhesive. The incident light was light with wavelengths of 380 nm to 780 nm from the standard light source D65. The incident angles were set to 5° and 45°. The results are shown in Tables 4 and 5.

[0110] Examples 2-13 Examples 2 to 13 differ from Example 1 in that at least one of the following was changed: the material of the transparent substrate 1, the thickness of the first high refractive index layer 41a, the thickness of the first low refractive index layer 41b, the thickness of the second high refractive index layer 42a, the thickness of the second low refractive index layer 42b, the material of the first high refractive index layer 41a, the material of the second high refractive index layer 42a, and the film thickness of the antifouling layer 5. The changes from Example 1 are summarized in Tables 2 and 3. Other conditions were the same as in Example 1, and the same evaluation was performed as in Example 1. The results are summarized in Tables 4 and 5.

[0111] "Comparative Examples 1-4" Examples 1 to 4 differ from Example 1 in that at least one of the following was changed: the material of the transparent substrate 1, the thickness of the first high refractive index layer 41a, the thickness of the first low refractive index layer 41b, the thickness of the second high refractive index layer 42a, and the thickness of the second low refractive index layer 42b. The changes from Example 1 are summarized in Tables 2 and 3. Other conditions were the same as in Example 1, and the same evaluation was performed as in Example 1. The results are summarized in Tables 4 and 5.

[0112] [Table 2]

[0113] [Table 3]

[0114] [Table 4]

[0115] [Table 5]

[0116] In the pen sliding test, visual judgment was as follows: "◎" indicated almost no change in the reflected color, "〇" indicated a slight change in the reflected color, and "×" indicated a significant change in the reflected color or partial peeling of the optical functional layer 4.

[0117] The evaluation in angular spectroscopy was performed as follows, and an overall evaluation was made: Δb * If the absolute value of the value is 6 or less, it is marked with "○", Δb * The absolute value of the value is 6 or less AND Δa * Values ​​whose absolute value is 10 or less are marked with "◎", |b * If the value was 6 or greater, it was marked with "×". [Explanation of Symbols]

[0118] 1…Transparent substrate, 2…Hard coat layer, 3…Adhesion layer, 4…Optical functional layer, 41a…First high refractive index layer, 41b…First low refractive index layer, 42a…Second high refractive index layer, 42b…Second low refractive index layer, 5…Anti-fouling layer, 10…Optical laminate

Claims

1. A transparent substrate, a hard coat layer, an adhesion layer, an optical functional layer, and an anti-fouling layer are laminated in that order. When a sliding test was conducted using a sliding tool with a Shore D hardness of 40 and a diameter of 0.8 mm, with a load of 250 g and 500 reciprocating cycles, the L of the sliding point before and after sliding was observed. ＊ a ＊ b ＊ b in the color system ＊ Change in value Δb ＊ The absolute value of is 1.9 or less, L of reflected light when incident at an incident angle of 5° ＊ a ＊ b ＊ b in the color system ＊ value, and L of reflected light when incident at an incident angle of 45° ＊ a ＊ b ＊ b in the color system ＊ value, and the amount of change Δb therebetween ＊ An optical layered body, wherein the absolute value of is 6.0 or less.

2. L of the reflected light when incident at an incident angle of 5° ＊ a ＊ b ＊ b in the color system ＊ The value and the L of the reflected light when incident at an angle of incidence of 45°. ＊ a ＊ b ＊ b in the color system ＊ The values ​​are -20 ≤ b ＊ The optical laminate according to claim 1, satisfying ≤ 10.

3. L of the reflected light when incident at an incident angle of 5° ＊ a ＊ b ＊ a in the color system ＊ The value and the L of the reflected light when incident at an angle of incidence of 45°. ＊ a ＊ b ＊ a in the color system ＊ The values ​​are -10 ≤ a ＊ The optical laminate according to claim 1, satisfying ≤ 20.

4. L of the reflected light when incident at an incident angle of 5° ＊ a ＊ b ＊ a in the color system ＊ The value and the L of the reflected light when incident at an angle of incidence of 45°. ＊ a ＊ b ＊ a in the color system ＊ Change amount Δa between the value and the value ＊ The optical laminate according to claim 1, wherein the absolute value of is 10 or less.

5. Chromatic difference ΔE due to differences in the angle of incidence of light ＊ ab is 19.4 or less, Chromatic difference ΔE due to differences in the angle of incidence of light ＊ ab is the L of the reflected light when incident at an angle of incidence of 5°. ＊ a ＊ b ＊ Value and the L of the reflected light when incident at an angle of incidence of 45° ＊ a ＊ b ＊ Value and ΔE ＊ ab = (ΔL ＊２ +Δa ＊２ +Δb ＊２ ) １／２ The optical laminate according to claim 1, which is obtained by [method].

6. The optical functional layer comprises, in order from the side closest to the adhesion layer, a first high refractive index layer, a first low refractive index layer, a second high refractive index layer, and a second low refractive index layer. Each of the first high refractive index layer and the second high refractive index layer has a higher refractive index than each of the first low refractive index layer and the second low refractive index layer. The physical thickness of the first high refractive index layer is 10 nm or more and 20 nm or less. The physical thickness of the first low refractive index layer is 2 nm or more and 15 nm or less. The optical laminate according to claim 1, wherein the physical thickness of the second low refractive index layer is 70 nm or more and 85 nm or less.

7. The optical functional layer comprises, in order from the side closest to the adhesion layer, a first high refractive index layer, a first low refractive index layer, a second high refractive index layer, and a second low refractive index layer. Each of the first high refractive index layer and the second high refractive index layer has a higher refractive index than each of the first low refractive index layer and the second low refractive index layer. The optical film thickness of the first high refractive index layer is 20 nm or more and 48.8 nm or less. The optical film thickness of the first low refractive index layer is 2.9 nm or more and 21.9 nm or less. The optical laminate according to claim 1, wherein the optical film thickness of the second low refractive index layer is 102 nm or more and 124.1 nm or less.

8. The optical laminate according to claim 1, wherein the total thickness of the physical film thickness of the optical functional layer is 170 nm or more and 220 nm or less.

9. The optical laminate according to claim 1, wherein the total thickness of the optical film thickness of the optical functional layer is 320 nm or more and 410 nm or less.

10. The optical laminate according to claim 1, wherein the physical thickness of the antifouling layer is 2 nm or more and 10 nm or less.

11. The optical laminate according to claim 1, wherein the optical functional layer is a sputtering film.

12. The optical laminate according to claim 1, wherein the antifouling layer is a vapor-deposited film.

13. The optical laminate according to claim 1, wherein the antifouling layer contains a fluorine-based compound.

14. An article comprising an optical laminate according to any one of claims 1 to 13.

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