WO2024157939A1

WO2024157939A1 - Multilayer body for display device, and display device

Info

Publication number: WO2024157939A1
Application number: PCT/JP2024/001691
Authority: WO
Inventors: 佳奈堀井; 純佐藤; 和也本田; 研一小野寺; 紗緒里川口; 朝香岡野
Original assignee: 大日本印刷株式会社
Priority date: 2023-01-23
Filing date: 2024-01-22
Publication date: 2024-08-02
Also published as: JP2024103994A; TW202438931A

Abstract

The present disclosure provides a multilayer body for a display device, comprising a base material layer, a functional layer, and an antireflective layer in the stated order in the thickness direction, wherein the ratio of elemental nitrogen in the antireflective layer-side surface thereof as measured by X-ray photoelectron spectroscopy is 0.5-2.5 at%.

Description

Laminate for display device and display device

This disclosure relates to a laminate for a display device and a display device.

In general, display devices such as smartphones, tablet terminals, and laptop computers require low surface reflectance to prevent external light such as sunlight and fluorescent lights from being reflected on the display screen, to give the display a high-end appearance, and to improve the visibility of characters and images. For this reason, laminates for display devices that have an anti-reflective layer on the surface have been developed.

For example, Patent Document 1 discloses an anti-reflection film formed on the surface of a substrate such as a liquid crystal display panel, which contains hollow particles having an average particle size within a specified range and a specified near-infrared absorption spectrum. Patent Document 2 discloses a transparent substrate having a laminate of thin layers on its main surface, the laminate of thin layers including a metallic functional layer and an anti-reflection coating that contains a layer containing zirconium silicon nitride.

JP 2021-54941 A Special table 2019-531497 publication

Laminates for display devices that are placed on the surface of a display device are required to have good scratch resistance so that they are less susceptible to scratches. On the other hand, laminates for display devices that have conventional anti-reflection layers have room for improvement in terms of scratch resistance.

This disclosure was made in consideration of the above problems, and its main objective is to provide a laminate for a display device that has excellent scratch resistance.

One embodiment of the present disclosure provides a laminate for a display device having a base layer, a functional layer, and an anti-reflection layer in this order in the thickness direction, in which the ratio of nitrogen elements is 0.5 atomic % or more and 2.5 atomic % or less when the surface on the anti-reflection layer side is measured by X-ray photoelectron spectroscopy.

Another embodiment of the present disclosure provides a display device comprising a display panel and the above-described display device laminate disposed on the viewer side of the display panel.

The present disclosure can provide a laminate for a display device that has anti-reflection properties and excellent scratch resistance.

FIG. 1 is a schematic cross-sectional view showing an example of a laminate for a display device according to the present disclosure. FIG. 2 is a schematic cross-sectional view showing another example of a laminate for a display device according to the present disclosure. FIG. 2 is a schematic cross-sectional view showing another example of a laminate for a display device according to the present disclosure. 1 is a schematic cross-sectional view showing an example of a display device according to the present disclosure.

Below, an embodiment of the present disclosure will be described with reference to the drawings. However, the present disclosure can be implemented in many different forms, and should not be interpreted as being limited to the description of the embodiment exemplified below. Furthermore, in order to make the explanation clearer, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual form, but these are merely examples and do not limit the interpretation of the present disclosure. Furthermore, in this specification and each figure, elements similar to those described above with reference to the previous figures are given the same reference numerals, and detailed explanations may be omitted as appropriate.

In this specification, when describing a mode in which another component is placed on a certain component, the term "above" or "below" is intended to include both cases in which another component is placed directly above or below a certain component so as to be in contact with the component, and cases in which another component is placed above or below a certain component with another component in between, unless otherwise specified. Also, in this specification, when describing a mode in which another component is placed on the surface of a certain component, the term "on the surface side" or "on the surface" is intended to include both cases in which another component is placed directly above or below a certain component so as to be in contact with the component, and cases in which another component is placed above or below a certain component with another component in between, unless otherwise specified.

Fig. 1 is a schematic cross-sectional view showing an example of a laminate for a display device of the present disclosure. As shown in Fig. 1, the laminate for a display device 1 of the present disclosure has a base layer 2, a functional layer 3, and an antireflection layer 4 in this order in the thickness direction _DT . The laminate for a display device 1 of the present disclosure is characterized in that, when the surface S1 on the antireflection layer 4 side is measured by X-ray photoelectron spectroscopy, the ratio of nitrogen elements is 0.5 atomic % or more and 2.5 atomic % or less.

The laminate for a display device according to the present disclosure has a ratio of nitrogen elements in the surface on the anti-reflection layer side within a specified range, and therefore has superior scratch resistance compared to a laminate for a display device having a conventional anti-reflection layer. This is presumably because the nitrogen-containing compound (e.g., a melamine-based compound) blended into the anti-reflection layer as a cross-linking agent forms a cross-linked structure with the resin contained in the anti-reflection layer and the functional layer, improving the surface hardness. Each component of the laminate for a display device according to the present disclosure will be described in detail below.

1. Parameters of the display laminate When the surface S1 on the antireflection layer side of the display laminate of the present disclosure is measured by X-ray photoelectron spectroscopy, the ratio of nitrogen element is 0.5 atomic % or more, preferably 0.6 atomic % or more, and more preferably 0.7 atomic % or more. The ratio of nitrogen element corresponds to the amount of nitrogen-containing compound blended as a crosslinking agent, such as a melamine-based compound, in the antireflection layer. If the amount of nitrogen-containing compound blended as a crosslinking agent is too small, the crosslink density in the antireflection layer becomes insufficient, and excellent scratch resistance cannot be obtained.

On the other hand, the ratio of the nitrogen element is 2.5 atomic % or less, more preferably 2.0 atomic % or less, and even more preferably 1.5 atomic % or less.
If the amount of the nitrogen-containing compound blended as a crosslinking agent is too large, the resin content is relatively reduced, resulting in a low crosslink density and making it impossible to obtain excellent scratch resistance. In addition, the scratch resistance of the nitrogen-containing compound itself is low, resulting in poor scratch resistance.

The ratio of the nitrogen element is 0.5 atomic % or more and 2.5 atomic % or less, preferably 0.6 atomic % or more and 2.0 atomic % or less, and more preferably 0.7 atomic % or more and 1.5 atomic % or less.

In this disclosure, the ratio of the nitrogen element is the ratio of the nitrogen element when the total amount of all elements obtained by measuring the surface S1 of the laminate for a display device on the anti-reflection layer side by X-ray photoelectron spectroscopy is taken as 100 atomic %.

One method for keeping the nitrogen element ratio within the above range is to adjust the type and content of the nitrogen-containing compound (e.g., melamine-based compound, etc.) in the anti-reflection layer.

In this disclosure, the ratio of the nitrogen element is a value measured by the following method. That is, a measurement sample is cut out from the laminate for a display device, and the X-ray photoelectron spectrum of the N1s orbital of the surface of the measurement sample on the anti-reflection layer side is measured under the following conditions using the X-ray photoelectron spectroscopy analyzer described below, and the ratio (atomic %) of the amount of N element to the amount of all elements is calculated.

(measuring device)
Kratos AXIS-NOVA
(Measurement condition)
Measurement method: Wide and Narrow
X-ray source: Monochrome AlKα
X-ray output: 150 W, emission current: 10 mA, acceleration voltage: 15 kV
Charge neutralization mechanism: ON
Measurement area: 300μm x 700μm
Pass Energy: Wide-160eV, Narrow-40eV

When the surface S1 on the anti-reflection layer side of the laminate for a display device of the present disclosure is measured by X-ray photoelectron spectroscopy, at least nitrogen element is detected. The nitrogen element includes nitrogen element derived from a nitrogen-containing compound described later, for example, a melamine-based compound. In addition to the nitrogen element, elements derived from, for example, a resin or low refractive index particles described later, for example, silicon, carbon, oxygen, aluminum, and other elements, may also be detected.

Furthermore, when the surface S1 on the anti-reflection layer side of the laminate for a display device of the present disclosure is measured by time-of-flight secondary ion mass spectrometry (TOF-SIMS), it is preferable that a structure derived from a nitrogen-containing compound, which will be described later, for example, a structure derived from a melamine-based compound, is detected.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a technique for analyzing the surface of a sample by measuring the time it takes for the secondary ions emitted from the sample to reach a detector after irradiating the sample with a beam of primary ions (e.g. bismuth ions) from a primary ion gun, and then separating the masses from the slight time difference (different masses result in different flight radii (times of flight)) to analyze the surface of the sample.

Specifically, when a time-of-flight secondary ion mass spectrometer (product name "TOF-SIMS5", manufactured by ION-TOF) is used and measurements are performed under the following measurement conditions, it is preferable that one or more fragments of C ₆ H ₇ N ₆ , C ₇ H ₉ N ₆ and C ₇ H ₉ N ₆ O are detected.

(Measurement condition)
Primary ion species: Bi3 ⁺⁺
Primary ion acceleration voltage: 25 kV
Primary ion current value: 0.2 pA
Frequency: 10kHz
・Measurement area: 200μm x 200μm
・Scan: 128pixel x 128pixel x 32scan
・Charging correction: Electron irradiation

2. Antireflection layer The antireflection layer in the present disclosure is disposed on the surface side opposite to the surface on the substrate layer side of the functional layer. The antireflection layer is a cured product formed from a composition for an antireflection layer containing a predetermined amount of a nitrogen-containing compound as a crosslinking agent. The antireflection layer contains a nitrogen-containing compound as a crosslinking agent. The antireflection layer preferably further contains a resin and low refractive index particles, or contains a low refractive index resin.

(1) Material The material for the antireflection layer in the present disclosure is not particularly limited as long as it is a material that can provide an antireflection layer that satisfies the above-mentioned analysis results by X-ray photoelectron spectroscopy.

(i) Nitrogen-containing compound The anti-reflection layer in the present disclosure contains a nitrogen-containing compound as a crosslinking agent. The crosslinking agent is usually present in a state of reacting with a resin or the crosslinking agent itself. Therefore, the nitrogen-containing compound is present in the anti-reflection layer in the present disclosure as an unreacted compound, a reacted compound, or a mixture thereof.

The nitrogen-containing compound is not particularly limited as long as it functions as a crosslinking agent, and examples thereof include melamine-based compounds. In this disclosure, a melamine-based compound refers to a compound having a melamine skeleton in the compound. Examples of melamine-based compounds include alkoxymethylated melamine, and specific examples include methoxymethylated melamine, propoxymethylated melamine, and butoxymethylated melamine. Of these, hexamethoxymethylated melamine is preferred. One type of nitrogen-containing compound may be used, or two or more types may be used in combination.

The content of the nitrogen-containing compound in the antireflective layer is not particularly limited as long as it is an amount that can obtain an antireflective layer surface that satisfies the analysis results by the X-ray photoelectron spectroscopy. The content of the nitrogen-containing compound in the antireflective layer is preferably 1 mass% or more, more preferably 2 mass% or more, and particularly preferably 5 mass% or more. On the other hand, it is preferably 30 mass% or less, more preferably 25 mass% or less, and particularly preferably 20 mass% or less. Here, the content of the nitrogen-containing compound in the antireflective layer means the content ratio relative to the total mass of solids in the antireflective layer composition before curing. The content of the nitrogen-containing compound in the antireflective layer is preferably 1 mass% or more and 30 mass% or less, more preferably 2 mass% or more and 25 mass% or less, and particularly preferably 5 mass% or more and 20 mass% or less.

(ii) Resin and Low Refractive Index Particles The antireflection layer according to the present disclosure may contain a resin and low refractive index particles having a refractive index lower than that of the resin. The resins may be bonded to each other via the nitrogen-containing compound.

The anti-reflection layer preferably contains, as a resin, a cured resin that has been cured by exposure to heat or ionizing radiation such as ultraviolet light or an electron beam. That is, the anti-reflection layer preferably contains, as a resin, a cured product of a curable resin composition such as a heat-curable resin composition or an ionizing radiation-curable resin composition. From the viewpoint of scratch resistance, it is more preferable that the anti-reflection layer contains a cured product of an ionizing radiation-curable resin composition. Examples of ionizing radiation-curable resin compositions include electron beam-curable resin compositions and ultraviolet light-curable resin compositions.

"Ionizing radiation" refers to electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules, and includes, for example, ultraviolet rays, electron beams, electromagnetic waves such as X-rays and gamma rays, and charged particle beams such as alpha rays and ion beams.

The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter also referred to as "ionizing radiation curable compound"). Examples of the ionizing radiation curable functional group include functional groups having an ethylenic double bond, such as a (meth)acryloyl group, a vinyl group, and an allyl group. As the ionizing radiation curable compound, a (meth)acrylate compound having a (meth)acryloyl group is more preferred. In this disclosure, a (meth)acryloyl group refers to an acryloyl group or a methcroyl group. In this disclosure, a (meth)acrylate refers to an acrylate or a methacrylate. It is preferable that the ionizing radiation curable compound has two or more ionizing radiation curable functional groups.

Examples of ionizing radiation curable compounds include compounds with one or more unsaturated bonds, such as compounds with acrylate functional groups. Examples of compounds with one unsaturated bond include ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, methylstyrene, and N-vinylpyrrolidone.

Examples of compounds having two or more unsaturated bonds include polyfunctional compounds such as polymethylolpropane tri(meth)acrylate, hexanediol (meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate, as well as reaction products of the above-mentioned polyfunctional compounds with (meth)acrylates, etc. (for example, poly(meth)acrylate esters of polyhydric alcohols).

Furthermore, as the ionizing radiation curable compound, polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiolpolyene resins, etc. having relatively low molecular weights and unsaturated double bonds can also be used. Furthermore, low refractive index resins, which will be described later, may also be used as the resin.

In the present disclosure, the ionizing radiation curable compound preferably has a reactive group capable of crosslinking with the nitrogen-containing compound. Examples of such reactive groups include a hydroxyl group, a carboxyl group, an amino group, etc.

Specific examples include pentaerythritol tri(meth)acrylate and dimethylaminoethyl (meth)acrylate.

The resin content in the anti-reflection layer is, for example, 3% by mass or more, and preferably 5% by mass or more. On the other hand, for example, it is 50% by mass or less, and preferably 40% by mass or less. The resin content in the anti-reflection layer is, for example, 3% by mass or more and 50% by mass or less, and preferably 5% by mass or more and 40% by mass or less. Here, the resin content in the anti-reflection layer means the ratio of the content of the above-mentioned curable compound to the total mass of solids in the anti-reflection layer composition before curing.

The anti-reflective layer may contain a polymerization initiator as necessary. The polymerization initiator may be appropriately selected from radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, etc. These polymerization initiators are decomposed by at least one of light irradiation and heating to generate radicals or cations, and cause radical polymerization and cationic polymerization to proceed. Note that there are cases where the polymerization initiator is completely decomposed and does not remain in the anti-reflective layer. When the ionizing radiation curable compound is an ultraviolet ray curable compound, the anti-reflective layer may contain a photopolymerization initiator.

In addition, the anti-reflection layer in the present disclosure preferably contains low refractive index particles. The low refractive index particles preferably have a refractive index lower than the refractive index of the resin.

The low refractive index particles may be either inorganic or organic particles. Examples of inorganic particles include inorganic particles such as silicon dioxide (silica), magnesium fluoride, lithium fluoride, calcium fluoride, and barium fluoride. Among these, silica particles are preferred.

The low refractive index particles may be, for example, hollow particles, solid particles, or porous particles, but among these, hollow particles and porous particles are preferred because of their low refractive index. Examples of hollow particles and porous particles include hollow silica particles, porous silica particles, porous polymer particles, and hollow polymer particles. Among these, hollow silica particles are preferred.

The low refractive index particles may also be surface-treated. By subjecting the low refractive index particles to a surface treatment, the affinity with the resin and the solvent is improved, the dispersion of the low refractive index particles becomes uniform, and the low refractive index particles are less likely to aggregate with each other, so that a decrease in the transparency of the antireflection layer, and a decrease in the coatability and film strength of the resin composition for the antireflection layer can be suppressed.

Examples of surface treatment methods include surface treatment using a silane coupling agent. Specific silane coupling agents can be the same as those disclosed in, for example, JP 2013-142817 A.

The low refractive index particles may also be reactive particles having polymerizable functional groups on their surfaces. Examples of reactive low refractive index particles include those used in low refractive index layers described in JP 2013-142817 A and the like.

The average particle size of the low refractive index particles may be less than the thickness of the antireflection layer, for example, 300 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less. The average particle size of the low refractive index particles may be, for example, 5 nm or more, 10 nm or more, 30 nm or more, or 50 nm or more. If the average particle size of the low refractive index particles is within the above range, the transparency of the antireflection layer is not impaired and a good dispersion state of the low refractive index particles is obtained. If the average particle size of the low refractive index particles is within the above range, the average particle size may be either a primary particle size or a secondary particle size, and the low refractive index particles may be linked in a chain shape. The average particle size of the low refractive index particles is, for example, preferably 5 nm or more and 300 nm or less, more preferably 10 nm or more and 200 nm or less, even more preferably 30 nm or more and 150 nm or less, and most preferably 50 nm or more and 100 nm or less.

Here, the average particle size of the low refractive index particles refers to the average value of 20 particles observed in a transmission electron microscope (TEM) photograph of the cross section of the anti-reflection layer. The average particle size of the inorganic particles described below is also a value observed in a similar manner.

The shape of the low refractive index particles is not particularly limited, and examples include spherical, chain-like, and needle-like shapes.

The content of low refractive index particles in the anti-reflection layer is appropriately set so that the refractive index of the entire anti-reflection layer satisfies the desired refractive index. The content of low refractive index particles in the anti-reflection layer is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more. On the other hand, it is preferably 85% by mass or less, more preferably 65% by mass or less, and even more preferably 50% by mass or less. The content of low refractive index particles is, for example, preferably 20% by mass or more and 85% by mass or less, more preferably 25% by mass or more and 65% by mass or less, and even more preferably 30% by mass or more and 50% by mass or less. If the content of low refractive index particles is too low, the desired refractive index may not be obtained. Also, if the content of low refractive index particles is too high, the haze of the anti-reflection layer may become high.

On the other hand, when the anti-reflection layer contains a low refractive index resin, the low refractive index resin may be any resin that allows the anti-reflection layer made of the low refractive index resin to have the desired refractive index, and examples of the low refractive index resin include fluororesin, silicone resin, acrylic resin, and olefin resin.

(iii) Additives The anti-reflection layer may contain various additives. Examples of the additives include silsesquioxane compounds. By blending a silsesquioxane compound, scratch resistance is further improved.

Examples of the silsesquioxane compound include compounds having a basic skeleton represented by the general formula _RSiO1.5 (R: organic group), and examples of the organic group include those having an acryloyl group, an amino group, an epoxy group, a carboxyl group, a methyl group, a phenyl group, a thiol group, etc.

The content of the silsesquioxane compound in the anti-reflective layer is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. On the other hand, it is preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 25% by mass or less. The content of the silsesquioxane compound in the anti-reflective layer is, for example, preferably 1% by mass or more and 70% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 25% by mass or less. If the content of the silsesquioxane compound is within the above range, the effect of improving scratch resistance can be obtained.

In addition, the antireflection layer preferably contains inorganic or organic particles, particularly inorganic particles, in addition to the low refractive index particles described above. When the antireflection layer contains inorganic or organic particles, the scratch resistance is improved. The inorganic or organic particles are the same as the inorganic or organic particles used in the hard coat layer described later. Among them, the antireflection layer preferably contains alumina (Al ₂ O ₃ ) particles. When the alumina particles are contained, the scratch resistance is further improved.

The average particle size of the inorganic particles contained in the anti-reflection layer is preferably 3 nm or more, and more preferably 10 nm or more. If the average particle size of the inorganic particles is too small, it is difficult to obtain scratch resistance. In addition, the average particle size of the inorganic particles is preferably 50 nm or less, and more preferably 35 nm or less. If the average particle size of the inorganic particles is too large, scratch resistance deteriorates and haze also increases.

The content of inorganic particles in the anti-reflective layer is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. On the other hand, it is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The content of inorganic particles in the anti-reflective layer is, for example, preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less. If the content of inorganic particles is within the above range, the effect of improving scratch resistance can be obtained.

The anti-reflection layer may contain other additives. Examples of other additives include leveling agents, ultraviolet absorbers, antioxidants, light stabilizers, infrared absorbers, dispersion aids, weather resistance improvers, scratch resistance improvers, antistatic agents, polymerization inhibitors, crosslinking agents, adhesion improvers, thixotropy imparting agents, coupling agents, plasticizers, defoamers, and fillers.

(2) Thickness The thickness of the antireflection layer is, for example, preferably 50 nm or more, more preferably 70 nm or more, and even more preferably 90 nm or more. If the thickness of the antireflection layer is in the above range or more, it can obtain scratch resistance and necessary antireflection effect. On the other hand, the thickness of the antireflection layer is, for example, preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 120 nm or less. If the thickness of the antireflection layer is in the above range or less, it can obtain excellent bending resistance and necessary antireflection effect.
Specifically, the thickness of the antireflection layer in the present disclosure is preferably 50 nm or more and 200 nm or less, more preferably 70 nm or more and 150 nm or less, and even more preferably 90 nm or more and 120 nm or less.

The thickness of the anti-reflection layer is a value measured from a cross section in the thickness direction of the laminate for a display device observed with a transmission electron microscope (TEM), a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM), and can be the average value of the thicknesses at 10 randomly selected locations. The same method can be used to measure the thicknesses of other layers in the laminate for a display device.

(3) Refractive index The refractive index of the anti-reflection layer is preferably 1.40 or less, more preferably 1.35 or less. If the refractive index of the anti-reflection layer is within the above range, the reflectance of the surface of the anti-reflection layer is prevented from increasing, and visibility can be easily improved. On the other hand, the refractive index of the anti-reflection layer is 1.10 or more.

In this specification, the refractive index refers to the refractive index for light with a wavelength of 550 nm. The refractive index is measured using an ellipsometer. Examples of ellipsometers include the UVSEL manufactured by Jobin Yvon and the DF1030R manufactured by Techno Synergy. The refractive index of the functional layer is measured in the same manner.

(4) Method for Forming Antireflection Layer As a method for forming an antireflection layer, for example, a method of applying a resin composition for an antireflection layer onto a functional layer and curing the composition can be mentioned.

The resin composition for the anti-reflection layer contains, for example, the nitrogen-containing compound, the curable resin composition, the low refractive index particles, an additive, and, if necessary, a solvent.

3. Functional layer The functional layer in the present disclosure is disposed between the substrate layer and the anti-reflection layer. Examples of the functional layer include a hard coat layer. The hard coat layer is a layer for increasing the surface hardness. By disposing the hard coat layer, it is possible to improve the scratch resistance. In particular, when the substrate layer is a resin substrate, by disposing the hard coat layer, it is possible to effectively improve the scratch resistance.

(1) Materials Examples of materials that can be used for the hard coat layer include organic materials, inorganic materials, and organic-inorganic composite materials.

Among them, the material of the hard coat layer is preferably an organic material. Examples of organic materials include a cured product of a curable resin composition such as a thermosetting resin composition or an ionizing radiation curable resin composition. Examples of curable resin compositions include the same curable resin composition as the antireflection layer described above.

The hard coat layer may contain a polymerization initiator as necessary. The polymerization initiator may be appropriately selected from radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, etc. These polymerization initiators are decomposed by at least one of light irradiation and heating to generate radicals or cations, and cause radical polymerization and cationic polymerization to proceed. Note that in the hard coat layer, the polymerization initiator may be completely decomposed and may not remain. When an ultraviolet-curable resin is used as the resin, the hard coat layer may contain a photopolymerization initiator.

The hard coat layer preferably contains inorganic or organic particles, and more preferably contains inorganic particles. By containing particles in the hard coat layer, the hardness can be improved.

Examples of inorganic particles include metal oxide particles such as silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconia, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, and cerium oxide, metal fluoride particles such as magnesium fluoride and sodium fluoride, metal particles, metal sulfide particles, and metal nitride particles. Among these, metal oxide particles are preferred, and at least one selected from silica particles and alumina particles is more preferred, with silica particles being even more preferred, because excellent hardness can be obtained.

The inorganic particles are preferably reactive inorganic particles having photoreactive reactive functional groups on at least a portion of the particle surface that undergo a crosslinking reaction between the inorganic particles themselves or between the inorganic particles and at least one type of polymerizable compound to form a covalent bond. The hardness of the hard coat layer can be further improved by crosslinking between the reactive inorganic particles themselves or between the reactive inorganic particles and at least one type of radically polymerizable compound and cationic polymerizable compound.

Reactive inorganic particles have at least a portion of their surface coated with an organic component, and have reactive functional groups on the surface introduced by the organic component. As the reactive functional group, for example, a polymerizable unsaturated group is preferably used, and a photocurable unsaturated group is more preferably used. As the reactive functional group, for example, ethylenically unsaturated bonds such as (meth)acryloyl groups, vinyl groups, and allyl groups, and epoxy groups can be mentioned.

The average particle size of the inorganic particles contained in the hard coat layer is preferably 3 nm or more, more preferably 10 nm or more, from the viewpoint of improving hardness. If the average particle size of the inorganic particles is too small, no improvement in hardness can be obtained. Furthermore, the average particle size of the inorganic particles is preferably 100 nm or less, more preferably 70 nm or less. If the average particle size of the inorganic particles is too large, the haze increases and surface smoothness cannot be obtained.

The hardness of the hard coat layer can be controlled by adjusting the size and content of the inorganic particles. For example, the content of inorganic particles in the hard coat layer may be, for example, 10% by mass or more, and may be 20% by mass or more. On the other hand, it may be 80% by mass or less, and may be 60% by mass or less. The content of inorganic particles in the hard coat layer may be, for example, 10% by mass or more, and 80% by mass or less, and may be 20% by mass or more, and 60% by mass or less.

The hard coat layer may contain a leveling agent. The leveling agent contained in the hard coat layer is not particularly limited, and examples thereof include silicone-based leveling agents, fluorine-based leveling agents, acrylic-based leveling agents, vinyl-based leveling agents, and the like. These leveling agents may be used alone or in combination of two or more. Among these, silicone-based leveling agents and fluorine-based leveling agents are preferred because of their high ability to reduce surface tension.

The content of the leveling agent in the hard coat layer is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more. On the other hand, it is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less. The content of the leveling agent in the hard coat layer is preferably 0.01% by mass or more and 3% by mass or less, more preferably 0.05% by mass or more and 2% by mass or less, and even more preferably 0.1% by mass or more and 1% by mass or less. If the content of the leveling agent is too low, the effect of the leveling agent may not be fully obtained. Also, if the content of the leveling agent is too high, the hardness of the hard coat layer may decrease.

(2) Thickness The thickness of the functional layer may be appropriately selected depending on the application of the display laminate. For example, the thickness of the functional layer is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more. On the other hand, it is preferably 30 μm or less, more preferably 15 μm or less, and even more preferably 8 μm or less. Specifically, the thickness of the functional layer is preferably 1 μm or more and 30 μm or less, more preferably 2 μm or more and 15 μm or less, and even more preferably 3 μm or more and 8 μm or less. If the thickness of the functional layer is within the above range, sufficient hardness as a functional layer can be obtained.

(3) Refractive index The refractive index of the functional layer is, for example, preferably 1.45 or more, more preferably 1.47 or more, and even more preferably 1.50 or more. On the other hand, it is preferably 1.80 or less, more preferably 1.75 or less, and even more preferably 1.70 or less. The refractive index of the functional layer is preferably 1.45 or more and 1.80 or less, more preferably 1.47 or more and 1.75 or less, and even more preferably 1.50 or more and 1.70 or less. By having the refractive index of the functional layer within the above range, the difference with the refractive index of the substrate layer and the difference with the refractive index of the antireflection layer can be reduced, and the reflection of light at the interface between the functional layer and the antireflection layer and the reflection of light at the interface between the functional layer and the substrate layer can be suppressed.

In addition, when the laminate for a display device in the present disclosure has a high refractive index layer described later, it is preferable that the refractive index of the functional layer is lower than that of the high refractive index layer. In this case, the refractive index of the functional layer is, for example, preferably 1.50 or more, more preferably 1.55 or more. On the other hand, it is preferably 2.20 or less, more preferably 1.80 or less. Specifically, the refractive index of the functional layer is preferably 1.50 or more and 2.20 or less, more preferably 1.55 or more and 1.80 or less. If the refractive index of the functional layer is in such a range, the functional layer serves as a medium refractive index layer, and interference action is possible between the three layers of the functional layer (medium refractive index layer), the high refractive index layer, and the anti-reflection layer (low refractive index layer), so that the reflectance can be further reduced.

(4) Formation Method As a method for forming the functional layer, for example, a method of applying a resin composition for the functional layer onto the above-mentioned base layer and curing the composition can be mentioned.

The substrate layer in the present disclosure is a member that supports the anti-reflection layer and the functional layer and has transparency. The substrate layer is not particularly limited as long as it has transparency, and examples thereof include a resin substrate and a glass substrate.

(1) Resin substrate The resin constituting the resin substrate is not particularly limited as long as it can provide a resin substrate having transparency, and examples thereof include polyimide resins, polyamide resins, polyester resins, etc. Examples of polyimide resins include polyimide, polyamideimide, polyetherimide, polyesterimide, etc. Examples of polyester resins include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc. Among them, polyimide resins, polyamide resins, or mixtures thereof are preferred because they have bending resistance and excellent hardness and transparency, and polyimide resins are more preferred.

There are no particular limitations on the polyimide resin as long as it can produce a resin substrate with transparency, but among the above, polyimide and polyamideimide are preferably used. They can increase flexibility and resistance to bending, and because they have a relatively high refractive index, they make it easier to adjust the reflectance.

(2) Glass Substrate The glass constituting the glass substrate is not particularly limited as long as it has transparency, and examples thereof include silicate glass, silica glass, etc. Among them, borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass are preferred, and alkali-free glass is more preferred. Examples of commercially available glass substrates include ultra-thin glass G-Leaf from Nippon Electric Glass Co., Ltd. and ultra-thin glass from Matsunami Glass Industry Co., Ltd.

It is also preferable that the glass constituting the glass substrate is chemically strengthened glass. Chemically strengthened glass has excellent mechanical strength and is therefore preferable in that it can be made thinner. Chemically strengthened glass is typically glass whose mechanical properties have been strengthened by chemical methods, such as by partially exchanging ion species near the surface of the glass, for example by replacing sodium with potassium, and has a compressive stress layer on the surface.

Examples of glass that can be used to make chemically strengthened glass substrates include aluminosilicate glass, soda-lime glass, borosilicate glass, lead glass, alkali barium glass, and aluminoborosilicate glass.

Commercially available chemically strengthened glass substrates include, for example, Corning's Gorilla Glass, AGC's Dragontrail, and Schott's chemically strengthened glass.

(3) Configuration of the Base Material Layer The thickness of the base material layer is not particularly limited and may be appropriately selected depending on the type of base material layer, etc.

The thickness of the resin substrate is, for example, preferably 10 μm or more, and more preferably 25 μm or more. On the other hand, it is preferably 100 μm or less, and more preferably 80 μm or less. Specifically, the thickness of the resin substrate is preferably 10 μm or more and 100 μm or less, and more preferably 25 μm or more and 80 μm or less. By having the thickness of the resin substrate within the above range, it is possible to obtain good flexibility and sufficient hardness. It is also possible to suppress curling of the laminate for a display device. Furthermore, it is preferable in terms of reducing the weight of the laminate for a display device.

The thickness of the glass substrate is, for example, preferably 200 μm or less, more preferably 100 μm or less, even more preferably 90 μm or less, and particularly preferably 80 μm or less. On the other hand, it is more preferably 15 μm or more, even more preferably 20 μm or more, and particularly preferably 25 μm or more. Specifically, the thickness of the glass substrate is preferably 15 μm or more and 100 μm or less, more preferably 20 μm or more and 90 μm or less, and particularly preferably 25 μm or more and 80 μm or less. By having the thickness of the glass substrate within the above range, it is possible to obtain good flexibility and sufficient hardness. In addition, curling of the display laminate can also be suppressed. Furthermore, it is preferable in terms of reducing the weight of the display laminate.

5. Other Layers (1) Impact Absorption Layer The display laminate in the present disclosure may have an impact absorption layer 5 between the substrate layer 2 and the functional layer 3, as shown in FIG. 2, or on the surface of the substrate layer 2 opposite to the functional layer 3, as shown in FIG. 3. By disposing the impact absorption layer, when an impact is applied to the display laminate, the impact can be absorbed and impact resistance can be improved. In addition, when the substrate layer is a glass substrate, cracking of the glass substrate can be suppressed.

The material for the impact absorbing layer is not particularly limited as long as it is capable of producing an impact absorbing layer having impact absorption and transparency, and examples include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), urethane resin, epoxy resin, polyimide, polyamide-imide, acrylic resin, triacetyl cellulose (TAC), silicone resin, etc. These materials may be used alone or in combination of two or more.

The impact absorbing layer may further contain additives as necessary. Examples of additives include inorganic particles, organic particles, ultraviolet absorbers, antioxidants, light stabilizers, surfactants, and adhesion improvers.

The thickness of the impact absorbing layer may be any thickness that is capable of absorbing impact, and may be, for example, preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. On the other hand, it may be preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less. Specifically, the thickness of the impact absorbing layer may be preferably 5 μm or more and 150 μm or less, more preferably 10 μm or more and 120 μm or less, and even more preferably 15 μm or more and 100 μm or less.

The impact absorbing layer may be, for example, a resin film. Also, for example, the impact absorbing layer may be formed by applying a composition for the impact absorbing layer onto the substrate layer.

(2) Adhesive Layer for Pasting The laminate for a display device in the present disclosure may have an adhesive layer for pasting 6 on the surface of the base layer 2 opposite to the functional layer 3, as shown in, for example, Figures 2 and 3. The laminate for a display device may be pasted to, for example, a display panel or the like via the adhesive layer for pasting.

The adhesive used in the attachment adhesive layer is not particularly limited as long as it is transparent and capable of adhering the display device laminate to a display panel or the like, and examples of such adhesives include heat-curing adhesives, ultraviolet-curing adhesives, two-component curing adhesives, hot-melt adhesives, and pressure-sensitive adhesives (so-called pressure-sensitive adhesives).

In particular, when the attachment adhesive layer 6, the shock absorbing layer 5, and the interlayer adhesive layer 7 described below are arranged in this order as shown in FIG. 3, it is preferable that the attachment adhesive layer and the interlayer adhesive layer contain a pressure-sensitive adhesive, that is, they are pressure-sensitive adhesive layers. In general, the pressure-sensitive adhesive layer is a relatively soft layer among the adhesive layers containing the above-mentioned adhesives. The shock absorbing layer is arranged between the relatively soft pressure-sensitive adhesive layers, thereby improving the shock resistance. This is because the pressure-sensitive adhesive layer is relatively soft and easily deformed, and therefore when an impact is applied to the display device laminate, the deformation of the shock absorbing layer is not suppressed by the pressure-sensitive adhesive layer, and the shock absorbing layer becomes more easily deformed, which is thought to result in a greater shock absorbing effect.

The thickness of the attachment adhesive layer is, for example, preferably 10 μm or more, more preferably 25 μm or more, and even more preferably 40 μm or more. On the other hand, it is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 60 μm or less. Specifically, the thickness of the attachment adhesive layer is preferably 10 μm or more and 100 μm or less, more preferably 25 μm or more and 80 μm or less, and even more preferably 40 μm or more and 60 μm or less. If the attachment adhesive layer is too thin, it may not be possible to sufficiently bond the display device laminate and the display panel, etc. Furthermore, if the attachment adhesive layer is too thick, flexibility may be impaired.

As the adhesive layer for application, for example, an adhesive film may be used. Also, for example, an adhesive composition may be applied onto a support or a base layer to form an adhesive layer for application.

(3) High Refractive Index Layer The laminate for display device in the present disclosure may have a high refractive index layer between the antireflection layer and the functional layer. The high refractive index layer is a layer having a refractive index higher than that of the functional layer, and contains high refractive index particles and a binder resin. The high refractive index layer contains a cured product of a curable resin composition such as a thermosetting resin composition or an ionizing radiation curable resin composition as a binder resin. As the curable resin composition, the same one as exemplified in the antireflection layer can be used, and an ionizing radiation curable resin composition is preferable. When the ionizing radiation curable compound is an ultraviolet ray curable compound, it is preferable that the ionizing radiation curable composition contains additives such as a photopolymerization initiator and a photopolymerization accelerator. As the photopolymerization initiator and the photopolymerization accelerator, the same one as the material for the antireflection layer can be used.

High refractive index particles include antimony pentoxide, zinc oxide, titanium oxide, cerium oxide, tin-doped indium oxide, antimony-doped tin oxide, yttrium oxide, and zirconium oxide.

The refractive index of the high refractive index layer is preferably 1.50 or more, and more preferably 1.55 or more. On the other hand, it is preferably 2.20 or less, and more preferably 1.80 or less. Specifically, the refractive index of the high refractive index layer is preferably 1.50 or more and 2.20 or less, and more preferably 1.55 or more and 1.80 or less. Furthermore, the thickness of the high refractive index layer is preferably 200 nm or less, and more preferably 180 nm or less. On the other hand, it is preferably 50 nm or more. Specifically, the thickness of the high refractive index layer is preferably 50 nm or more and 180 nm or less.

(4) Interlayer Adhesive Layer In the laminate for a display device according to the present disclosure, an interlayer adhesive layer may be disposed between each of the layers.

The adhesive used in the interlayer adhesive layer can be the same as the adhesive used in the attachment adhesive layer described above.

The thickness and formation method of the interlayer adhesive layer can be the same as those of the attachment adhesive layer.

6. Use of the laminate for a display device The laminate for a display device according to the present disclosure can be used as a front panel arranged on the viewer side of the display panel in a display device. In particular, the laminate for a display device according to the present disclosure can be suitably used as a front panel in a flexible display device such as a foldable display, a rollable display, or a bendable display.

Furthermore, the display device laminate of the present disclosure can be used for the front panel of display devices such as smartphones, tablet terminals, wearable terminals, personal computers, televisions, digital signage, public information displays (PIDs), and in-vehicle displays.

B. Display Device A display device according to the present disclosure includes a display panel and the laminate for a display device described above, which is disposed on the viewer's side of the display panel.

FIG. 4 is a schematic cross-sectional view showing an example of a display device according to the present disclosure. As shown in FIG. 4, the display device 50 includes a display panel 51 and a laminate for a display device 1 arranged on the viewer's side of the display panel 51. In the display device 50, the laminate for a display device 1 and the display panel 31 can be bonded together, for example, via an attachment adhesive layer 6 of the laminate for a display device 1.

The display device of the present disclosure has excellent surface scratch resistance because it includes the laminate for a display device described above.

When the laminate for a display device according to the present disclosure is disposed on the surface of a display device, the anti-reflection layer is disposed on the outside and the base layer is disposed on the inside.

The method for disposing the display device laminate of the present disclosure on the surface of the display device is not particularly limited, but may include, for example, a method using an adhesive layer.

Display panels in this disclosure include, for example, display panels used in display devices such as organic EL display devices and liquid crystal display devices.

The display device of this disclosure can have a touch panel member between the display panel and the display device laminate.

The display device in this disclosure is preferably a flexible display device such as a foldable display, a rollable display, or a bendable display.

Note that this disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical ideas described in the claims of this disclosure and provides similar effects is included within the technical scope of this disclosure.

The following examples and comparative examples will explain this disclosure in more detail.

[Comparative Example 1]
(1) Formation of Hard Coat Layer First, the components were mixed so as to obtain the composition shown below, to prepare a composition 1 for hard coat layer (HC layer).

<Hardcoat layer composition 1>
Urethane acrylate (Daicel Allnex "EBECRYL8254") 10 parts by weight Polymerization initiator (IGM Resins B.V. "Omnirad184") 0.6 parts by weight Silica particles (solid content 20% by weight, solvent MIBK (methyl isobutyl ketone), average primary particle size 45 nm) 25 parts by weight Leveling agent BYK "BYK-300" 0.02 parts by weight Solvent MIBK (methyl isobutyl ketone) 17 parts by weight

A polyimide film having a thickness of 50 μm ("Neoprim" manufactured by Mitsubishi Gas Chemical Company, Inc.) was used as the substrate layer, and the above-mentioned resin composition 1 for hard coat layer was applied onto the substrate layer to form a coating film.
The coating film was then heated at 70° C. for 1 minute to evaporate the solvent in the coating film, and the coating film was cured by irradiating it with ultraviolet light using an ultraviolet irradiation device (manufactured by Fusion UV Systems Japan, light source H bulb) at an oxygen concentration of 200 ppm or less and an accumulated light amount of 40 mJ/ ^cm2 to form a hard coat layer having a thickness of 5 μm.

(2) Formation of Antireflection Layer The components were mixed so as to obtain the composition shown below, thereby preparing a base composition 1.

<Composition of Base Composition 1>
Pentaerythritol triacrylate (PETA): "Light Acrylate PE-3A" manufactured by Kyoeisha 3.0 parts by mass Silsesquioxane: "Acryloyl polysilsesquioxane cage mixture" manufactured by Construe Chemical 7.0 parts by mass Polymerization initiator: IGM Resins B.V. "Omnirad 184" manufactured by Shin-Etsu Chemical Co., Ltd. 4.0 parts by mass Hollow silica particles (solid content 20% by mass, solvent MIBK (methyl isobutyl ketone), average primary particle diameter 50 nm) 75.0 parts by mass Silica particles (solid content 46% by mass, solvent MIBK (methyl isobutyl ketone), average primary particle diameter 12 nm) 5.5 parts by mass Alumina particles (solid content 30% by mass, solvent MIBK (methyl isobutyl ketone), average primary particle diameter 15 nm) 5.5 parts by mass Leveling agent ("KY-1203" manufactured by Shin-Etsu Chemical Co., Ltd.: solid content 20%, mixed solvent of MEK (methyl ethyl ketone) and MIBK (methyl isobutyl ketone)) 13.5 parts by mass Solvent (MIBK (methyl isobutyl ketone)) 710 parts by mass

A base composition 1 was applied onto the hard coat layer as a resin composition for an anti-reflection layer to form a coating film. The coating film was heated at 70°C for 1 minute to evaporate the solvent in the coating film, and then irradiated with ultraviolet light using an ultraviolet irradiator (manufactured by Fusion UV Systems Japan, light source H bulb) so that the oxygen concentration was 200 ppm or less and the cumulative light amount was 400 mJ/ ^cm2 to harden the coating film, forming an anti-reflection layer with a thickness of 100 nm. This resulted in a laminate for a display device.

[Example 1]
In the same manner as in Comparative Example 1, a composition 1 for a hard coat layer was prepared, and a hard coat layer was formed on a substrate layer.
A methylated melamine compound (hexamethoxymethylmelamine) was added to the base composition 1. At this time, the methylated melamine compound was added so that it was 2 mass% relative to the total mass of the solid content. Next, the mixture was adjusted with MIBK (methyl isobutyl ketone) so that the final solid content was 4%, to obtain a composition for an antireflection layer. Except for using this composition for an antireflection layer, an antireflection layer was formed on the hard coat layer in the same manner as in Comparative Example 1, to obtain a laminate for a display device.

[Examples 2 to 5, Comparative Examples 2 and 3]
In the same manner as in Comparative Example 1, a composition 1 for a hard coat layer was prepared, and a hard coat layer was formed on a substrate layer.
A methylated melamine compound (hexamethoxymethylmelamine) was added to the base composition 1. At this time, the methylated melamine compound was added in an amount (mass%) shown in Table 1 relative to the total mass of the solid content of the composition for antireflection layer. Next, the final solid content was adjusted to 4% with MIBK (methyl isobutyl ketone) to prepare a composition for antireflection layer. Except for using this composition for antireflection layer, an antireflection layer was formed on the hard coat layer in the same manner as in Comparative Example 1, and a laminate for a display device was obtained.

[Example 6]
(1) Formation of Hard Coat Layer First, the components were mixed so as to obtain the composition shown below, thereby preparing a composition 2 for hard coat layer.

<Hardcoat layer composition 2>
Urethane acrylate: Daicel Allnex "EBECRYL8254" 15 parts by weight Polymerization initiator: IGM Resins B.V. "Omnirad184" 0.6 parts by weight Leveling agent: BYK "BYK-300" 0.02 parts by weight Solvent: MIBK (methyl isobutyl ketone) 36 parts by weight

Next, a 50 μm thick polyimide film ("Neoprim" manufactured by Mitsubishi Gas Chemical Co., Ltd.) was used as a substrate layer, and the above-mentioned hard coat layer resin composition 2 was applied onto the substrate layer to form a coating film. The coating film was then heated at 70° C. for 1 minute to evaporate the solvent in the coating film, and then irradiated with ultraviolet light using an ultraviolet irradiator (manufactured by Fusion UV Systems Japan, light source H bulb) so that the oxygen concentration was 200 ppm or less and the cumulative light amount was 40 mJ/cm ² to harden the coating film, forming a 5 μm thick hard coat layer.

(2) Formation of Antireflection Layer A methylated melamine compound (hexamethoxymethylmelamine) was added to the above-mentioned base composition 1. At this time, the methylated melamine compound was added in an amount (mass%) shown in Table 1 relative to the total mass of the solid content of the composition for antireflection layer. Next, the final solid content was adjusted to 4% with MIBK (methyl isobutyl ketone) to prepare a composition for antireflection layer. Except for using this composition for antireflection layer, an antireflection layer was formed on the hard coat layer in the same manner as in Comparative Example 1 to obtain a laminate for a display device.

[Example 7]
(1) Formation of Hard Coat Layer In the same manner as in Example 6, a composition 2 for a hard coat layer was prepared, and a hard coat layer was formed on a substrate layer.

(2) Formation of Antireflection Layer Base composition 2 was prepared by blending the components shown below.

<Composition of Base Composition 2>
Pentaerythritol triacrylate (PETA) (Kyoeisha's "Light Acrylate PE-3A") 3.0 parts by mass; Silsesquioxane (Constru Chemical's "Acryloyl polysilsesquioxane cage mixture") 7.0 parts by mass; Polymerization initiator (IGM Resins B.V.'s "Omnirad 184") 4.0 parts by mass; Hollow silica particles (solid content 20% by mass, solvent MIBK (methyl isobutyl ketone), average primary particle size 50 nm) 75.0 parts by mass; Leveling agent ((Shin-Etsu Chemical's "KY-1203": solid content 20%, mixed solvent of MEK (methyl ethyl ketone) and MIBK (methyl isobutyl ketone)) 13.5 parts by mass; Solvent MIBK (methyl isobutyl ketone) 610 parts by mass

A methylated melamine compound (hexamethoxymethylmelamine) was added to the above-mentioned base composition 2 to prepare a composition for an anti-reflection layer. At this time, the methylated melamine compound was added so that it was 10 mass% based on the total mass of the solid content of the composition for an anti-reflection layer. Except for using this composition for an anti-reflection layer, an anti-reflection layer was formed on the hard coat layer in the same manner as in Comparative Example 1, and a laminate for a display device was obtained.

[Example 8]
(1) Formation of Hard Coat Layer In the same manner as in Comparative Example 1, a composition 1 for a hard coat layer was prepared, and a hard coat layer was formed on a substrate layer.

(2) Formation of Antireflection Layer Base composition 3 was prepared by blending the components shown below.

<Composition of Base Composition 3>
Pentaerythritol triacrylate (PETA): 3.0 parts by mass of "Light Acrylate PE-3A" manufactured by Kyoeisha Polymerization initiator: IGM Resins B.V. "Omnirad 184" manufactured by Shin-Etsu Chemical Co., Ltd. 4.0 parts by mass Hollow silica particles (solid content 20% by mass, solvent MIBK (methyl isobutyl ketone), average primary particle diameter 50 nm) 75.0 parts by mass Silica particles (solid content 46% by mass, solvent MIBK (methyl isobutyl ketone), average primary particle diameter 12 nm) 5.5 parts by mass Alumina particles (solid content 30% by mass, solvent MIBK (methyl isobutyl ketone), average primary particle diameter 15 nm) 5.5 parts by mass Leveling agent ("KY-1203" manufactured by Shin-Etsu Chemical Co., Ltd.: solid content 20%, mixed solvent of MEK (methyl ethyl ketone) and MIBK (methyl isobutyl ketone)) 13.5 parts by mass Solvent MIBK (methyl isobutyl ketone) 710 parts by mass

A methylated melamine compound (hexamethoxymethylmelamine) was added to the above-mentioned base composition 3 to prepare a composition for an anti-reflection layer. At this time, the methylated melamine compound was added so that it was 10 mass% based on the total mass of the solid content of the composition for an anti-reflection layer. Except for using this composition for an anti-reflection layer, an anti-reflection layer was formed on the hard coat layer in the same manner as in Comparative Example 1, and a laminate for a display device was obtained.

[Nitrogen element ratio measurement by X-ray photoelectron spectroscopy]
A measurement sample was cut out from the obtained laminate for a display device, and the X-ray photoelectron spectrum of the N1s orbital of the antireflection layer surface of the measurement sample was measured under the following conditions using the X-ray photoelectron spectrometer described below, and the ratio (atomic %) of the amount of N element to the amount of all elements was calculated. The results are shown in Table 1.

(measuring device)
Kratos AXIS-NOVA
(Measurement condition)
Measurement method: Wide and Narrow
X-ray source: Monochrome AlKα
X-ray output: 150 W, emission current: 10 mA, acceleration voltage: 15 kV
Charge neutralization mechanism: ON
Measurement area: 300 x 700μm
Pass Energy: Wide-160eV, Narrow-40eV

[Steel wool resistance test]
The scratch resistance of the laminates for displays obtained in Examples 1 to 8 and Comparative Examples 1 to 3 was evaluated according to the following test method and evaluation criteria.

Test method: Using a Gakushin-type friction fastness tester AB-301 manufactured by Tester Sangyo Co., Ltd., a PET protective film (SAT TM30125 manufactured by San-A Chemical Co., Ltd.) was attached with a roller to the non-measurement surface of a laminate measuring 5 cm x 10 cm, and the laminate was fixed on a glass plate on all four sides with Cellophane Tape (registered trademark) so as not to cause any folds or wrinkles. Next, using #0000 steel wool (Bonstar #0000 manufactured by Nippon Steel Wool Co., Ltd.), the steel wool was fixed to a jig measuring 2 cm x 2 cm, and the anti-reflection layer side surface of the laminate for display device was rubbed back and forth 300 times under the conditions of a load of 1 kg/4 cm ² , a moving speed of 100 mm/sec, and a moving distance of 50 mm.

Evaluation Method: For the laminate that had been subjected to the above test, the surface within a central 30 mm range excluding the ranges of 10 mm at both ends where the moving speed was unstable was observed through a fluorescent lamp and evaluated according to the following evaluation criteria.

Evaluation Criteria A: Pass (less than 5 scratches)
B: Pass (5 to 15 scratches)
C: Failed (15 or more scratches)

From Table 1, it was confirmed that Examples 1 to 8, in which the ratio of nitrogen elements is within the specified range, have better steel wool resistance test results and are superior in abrasion resistance than Comparative Examples 1 to 3. Furthermore, when Example 3 and Example 8 are compared, it was confirmed that Example 3, in which the anti-reflection layer contains a silsesquioxane compound, has superior abrasion resistance compared to Example 8, in which the anti-reflection layer does not contain a silsesquioxane compound. Note that in Comparative Example 1, nitrogen elements were detected even though the amount of methylated melamine compound added was 0 mass%. This is presumably due to the elution of the urethane acrylate contained in the hard coat layer, and the detection of nitrogen elements derived from the urethane acrylate.

That is, the present disclosure provides the following inventions.
[1] A laminate for a display device having a base layer, a functional layer, and an antireflection layer in this order in a thickness direction,
A laminate for a display device, wherein a ratio of nitrogen elements is 0.5 atomic % or more and 2.5 atomic % or less when the surface on the antireflection layer side is measured by X-ray photoelectron spectroscopy.
[2] The laminate for a display device according to [1], wherein the nitrogen element includes a nitrogen element derived from a melamine-based compound.
[3] The laminate for a display device according to [1] or [2], wherein the antireflection layer contains a silsesquioxane compound.
[4] The laminate for a display device according to any one of [1] to [3], wherein the antireflection layer contains low refractive index particles.
[5] The laminate for a display device according to [4], wherein the low refractive index particles are hollow silica particles.
[6] The laminate for a display device according to any one of [1] to [5], wherein the antireflection layer has a thickness of 50 nm or more and 200 nm or less.
[7] The laminate for a display device according to any one of [1] to [6], wherein the functional layer has a thickness of 1 μm or more and 30 μm or less.
[8] The laminate for a display device according to any one of [1] to [7], further comprising an impact absorbing layer on the side of the base layer opposite to the functional layer, or between the base layer and the functional layer.
[9] The laminate for a display device according to any one of [1] to [8], further comprising an adhesive layer for attachment on the side of the base layer opposite to the functional layer.
[10] A display device comprising: a display panel; and the laminate for a display device according to any one of [1] to [9], which is disposed on a viewer's side of the display panel.

REFERENCE SIGNS LIST 1 laminate for display device 2 substrate layer 3 functional layer 4 anti-reflection layer 5 impact absorbing layer 6 attachment adhesive layer 7 interlayer adhesive layer 50 display device 51 display panel

Claims

A laminate for a display device having a base layer, a functional layer, and an anti-reflection layer in this order in a thickness direction,
A laminate for a display device, wherein a ratio of nitrogen elements is 0.5 atomic % or more and 2.5 atomic % or less when the surface on the antireflection layer side is measured by X-ray photoelectron spectroscopy.
The laminate for a display device according to claim 1, wherein the nitrogen element includes a nitrogen element derived from a melamine-based compound.
The laminate for a display device according to claim 1, wherein the anti-reflection layer contains a silsesquioxane compound.
The laminate for a display device according to claim 1, wherein the anti-reflection layer contains low refractive index particles.
The laminate for a display device according to claim 4, wherein the low refractive index particles are hollow silica particles.
The laminate for a display device according to claim 1, wherein the thickness of the anti-reflection layer is 50 nm or more and 200 nm or less.
The laminate for a display device according to claim 1, wherein the thickness of the functional layer is 1 μm or more and 30 μm or less.
The laminate for a display device according to claim 1, which has an impact absorbing layer on the side of the base layer opposite the functional layer, or between the base layer and the functional layer.
The laminate for a display device according to claim 1, which has an adhesive layer for attachment on the side of the base layer opposite the functional layer.
A display panel;
A display device comprising: the laminate for a display device according to claim 1 , which is disposed on a viewer's side of the display panel.