TW202136035A - Optical laminate and display device - Google Patents

Abstract

The purpose of the present invention is to provide an optical laminate in which cracks do not readily occur in a resin film provided to a touch sensor layer when using a laser to cut the optical laminate into a prescribed shape. An optical laminate comprising a front surface panel, a polarization layer, and a touch sensor layer, the touch sensor layer having a transparent conductive layer and a resin film, and a prescribed range being set for a parameter A which is calculated from the glass transition temperature and the absorption of light at a wavelength of 9.3 [mu]m of the resin film provided to the optical laminate.

Description

Optical laminate and display device

The invention relates to an optical laminate and a display device.

Patent Document 1 describes a bendable optical laminate including a polarizing film, a retardation film, a film base material, and a transparent conductive layer in this order. Patent Document 1 describes an organic EL display device in which a window is arranged on one surface of the optical laminate, and an organic electroluminescence (EL) display panel is arranged on the other surface. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2016-126130

[The problem to be solved by the invention] An optical laminate including a front surface plate, a polarizing layer, and a touch sensor layer in this order may have low durability against bending. When investigating the cause, it was found that when the optical laminate was cut into a predetermined shape by laser, a small crack (length of 200 μm or less) was generated in the resin film included in the touch sensor layer. Furthermore, regardless of the direction in which the crack advances, the crack affects the decrease in the flexibility of the entire optical laminate. That is, it has been clarified that the optical layered body is easily broken in a direction parallel to the bending axis due to the crack during bending. The object of the present invention is to provide an optical laminated body, when the optical laminated body is cut into a predetermined shape using a laser, cracks are not easily generated on the resin film included in the touch sensor layer.

（1） 〔式（1）中， Tg_i 表示光學積層體所包含的第i個樹脂膜的玻璃轉移溫度（℃），a_i 表示光學積層體所包含的第i個樹脂膜對波長9.3 μm的光的吸光度， n表示1以上且5以下的整數〕。 [2]如[1]所述的光學積層體，其中所述觸控感測器層自所述前表面板側起依次具有所述透明導電層、及所述樹脂膜， 所述樹脂膜的玻璃轉移溫度（℃）為100℃以上且300℃以下， 所述樹脂膜對波長9.3 μm的光的吸光度為0.01以上且1.0以下。 [3]如[1]或[2]所述的光學積層體，其中所述前表面板具有樹脂膜，且 所述樹脂膜的玻璃轉移溫度（℃）為200℃以上且500℃以下， 所述樹脂膜對波長9.3 μm的光的吸光度為0.01以上且1.0以下。 [4]如[1]～[3]中任一項所述的光學積層體，其中所述偏光層具有樹脂膜，且 所述樹脂膜的玻璃轉移溫度（℃）為100℃以上且300℃以下， 所述樹脂膜對波長9.3 μm的光的吸光度為0.01以上且1.0以下。 [5]如[1]～[4]中任一項所述的光學積層體，其中所述前表面板、所述偏光層、及所述觸控感測器層分別包括一張樹脂膜。 [6]一種顯示裝置，具有如[1]～[5]中任一項所述的光學積層體。 [7]一種製造方法，為製造如[1]～[5]中任一項所述的光學積層體的方法，其包括使雷射光自視覺辨認側入射，並藉由雷射裁斷成規定形狀的步驟。[Means for Solving the Problem] [1] An optical laminate including a front surface plate, a polarizing layer, and a touch sensor layer, wherein the touch sensor layer has a transparent conductive layer and a resin film, and The parameter A represented by the formula (1) is 41 or more and 1200 or less,

(1) [In formula (1), Tg _i represents the glass transition temperature (℃) _{of the ith resin film contained in the optical laminate, and a i} represents the ith resin film contained in the optical laminate versus the wavelength of 9.3 μm The absorbance of light, n represents an integer of 1 or more and 5 or less]. [2] The optical laminate according to [1], wherein the touch sensor layer has the transparent conductive layer and the resin film in this order from the front surface plate side, and the resin film The glass transition temperature (°C) is 100°C or more and 300°C or less, and the absorbance of the resin film to light with a wavelength of 9.3 μm is 0.01 or more and 1.0 or less. [3] The optical laminate according to [1] or [2], wherein the front surface plate has a resin film, and the glass transition temperature (°C) of the resin film is 200°C or more and 500°C or less, The absorbance of the resin film to light with a wavelength of 9.3 μm is 0.01 or more and 1.0 or less. [4] The optical laminate according to any one of [1] to [3], wherein the polarizing layer has a resin film, and the glass transition temperature (°C) of the resin film is 100°C or higher and 300°C Hereinafter, the absorbance of the resin film with respect to light having a wavelength of 9.3 μm is 0.01 or more and 1.0 or less. [5] The optical laminate according to any one of [1] to [4], wherein the front surface plate, the polarizing layer, and the touch sensor layer each include a resin film. [6] A display device having the optical laminate according to any one of [1] to [5]. [7] A manufacturing method for manufacturing the optical laminate according to any one of [1] to [5], which includes making laser light enter from the visually recognizable side and cutting it into a predetermined shape by laser A step of.

[Effects of the invention] According to the present invention, there is provided an optical laminate. When the optical laminate is cut into a predetermined shape using a laser, cracks are less likely to occur in the resin film included in the touch sensor layer.

[Optical Laminate] FIG. 1 is a cross-sectional view showing an example of the structure of the optical laminate of the present invention. The optical laminate 100 shown in FIG. 1 includes a front surface plate 1, a polarizing layer 2, and a touch sensor layer 3 in sequence. The front surface plate 1, the polarizing layer 2, and the touch sensor layer 3 are laminated with each other via the bonding layer 4. The front panel 1 has a hard coat layer 11 and a resin film 10. The polarizing layer 2 has a resin film 21, a polarizer 20, and a retardation film 22. In addition, the bonding layer which bonds the polarizer 20 and the resin film 21, and the bonding layer which bonds the polarizer 20 and the retardation film 22 are not shown in figure. The touch sensor layer 3 has a resin film 32 and a transparent conductive layer 31. The touch sensor layer 3 has a transparent conductive layer 31 and a resin film 32 in this order from the front surface plate 1 side. In the optical laminate 100 shown in FIG. 1, the front surface plate 1, the polarizing layer 2, and the touch sensor layer 3 each include one resin film (that is, the number of resin films the optical laminate 100 has is 3).

The optical laminate may include layers other than those shown in FIG. 1. The optical laminate may include, for example, a resin film arranged between the front surface plate 1 and the polarizing layer 2 and a resin film arranged on the side of the retardation film 22 opposite to the polarizer 20 side. The number of resin films included in the optical layered body 100 is 1 or more and 5 or less. In order to improve the flexibility of the optical laminate, the number of resin films included in the optical laminate 100 may be 2 or more and 4 or less, and preferably 3 or 4.

（1） 〔式（1）中，Tg_i 表示光學積層體所包含的第i個樹脂膜的玻璃轉移溫度（°C），a_i 表示光學積層體所包含的第i個樹脂膜對波長9.3 μm的光的吸光度，n表示1以上且5以下的整數。〕In the optical layered body of the present invention, the parameter A represented by the following formula (1) is 41 or more and 1200 or less.

(1) [In formula (1), Tg _i represents the glass transition temperature (°C) _{of the i-th resin film contained in the optical laminate, and a i} represents the wavelength 9.3 of the i-th resin film contained in the optical laminate For the absorbance of light in μm, n represents an integer of 1 or more and 5 or less. 〕

In the present invention, the resin film refers to a film made of resin having a thickness of 10 μm or more. A resin film with a thickness of less than 10 μm is not suitable for the resin film of the present invention. In addition, even if the thickness is 10 μm or more, a film that is not formed of resin like glass is not suitable for the resin film of the present invention. The upper limit of the thickness of the resin film is not particularly limited, and may be, for example, 100 μm.

In the present invention, the first resin film may be the resin film located on the most front surface plate side in the optical laminate, and the nth resin film may be the resin film located on the most touch sensor layer side in the optical laminate. The resin film. In FIG. 1, the first resin film is the resin film 10, the second resin film is the resin film 21, and the third resin film is the resin film 32.

The glass transition temperature of the resin film can be measured with a differential scanning calorimetry device. Specifically, the glass transition temperature of the resin film can be measured by the method described in Examples described later. As a measuring device, Q-1000 manufactured by TA Instruments (Instruments) can be used.

The absorbance of the resin film to light with a wavelength of 9.3 μm can be measured by a Fourier transform infrared spectrophotometer. Specifically, the absorbance of the resin film with respect to light having a wavelength of 9.3 μm can be measured by the method described in Examples described later. As the measuring device, FT/IR-6300 manufactured by JASCO Corporation can be used.

By setting the parameter A represented by the formula (1) to be 41 or more and 1200 or less, when the optical laminate is cut, the resin film included in the touch sensor layer 3 is less likely to generate micro cracks. As a result, when the optical layered body is bent, the optical layered body is unlikely to be broken in a direction parallel to the bending axis. Furthermore, in this specification, "crack" refers to a length of 200 μm or less, and the crack can be mainly generated by cutting. The so-called "crack" refers to a phenomenon in which the optical layered body breaks linearly from one end to the other end thereof, and the cracking can occur when the optical layered body is bent. The parameter A is preferably 42 or more and 500 or less, more preferably 45 or more and 120 or less, more preferably 45 or more and 100 or less, may be 50 or more and 80 or less, or may be 58 or more and 80 or less. A resin film with a high glass transition temperature and a high absorbance of light with a wavelength of 9.3 μm can efficiently generate heat when irradiated with laser light. Therefore, before the resin film included in the touch sensor layer is deformed by heat, the optical laminate is likely to be cut, so it is estimated that cracks are less likely to occur.

On the other hand, from the viewpoint of improving the flexibility of the optical laminate, the glass transition temperature and the absorbance of light with a wavelength of 9.3 μm can be reduced to some extent. This is because a thin resin film makes it easier to improve flexibility, and the absorbance of light with a wavelength of 9.3 μm also depends on the thickness of the resin film. Moreover, this is because most resin films with a high glass transition temperature are hard films and tend to crack when bent.

The parameter A can be adjusted by selecting the type or number of resin films included in the optical laminate. When the optical layered body has a resin film with a high glass transition temperature and a large absorbance of light with a wavelength of 9.3 μm, or when the number of resin films included in the optical layered body is large, the parameter A tends to increase. On the other hand, when the optical laminate has a resin film with a low glass transition temperature and a small absorbance of light with a wavelength of 9.3 μm, or when the number of resin films in the optical laminate is small, the parameter A tends to change small.

The optical layered body is preferably bendable at least in the direction in which the front surface plate 1 is inside. Being able to bend means that it can be bent in a direction in which the front surface panel 1 is inside without cracking. The optical laminate of the present invention is excellent in bending resistance.

The shape of the optical laminate in the plane direction may be, for example, a square shape, preferably a square shape having long sides and short sides, and more preferably a rectangular shape. When the shape of the optical laminate in the plane direction is a rectangle, the length of the long side may be, for example, 10 mm to 1400 mm, and preferably 50 mm to 600 mm. The length of the short side is, for example, 5 mm to 800 mm, preferably 30 mm to 500 mm, and more preferably 50 mm to 300 mm. For each layer constituting the optical layered body, the corners may be R processed, or the end may be cut, or punched.

The thickness of the optical laminate varies depending on the functions required of the optical laminate and the use of the laminate, and therefore is not particularly limited, but is, for example, 20 μm to 1,000 μm, preferably 50 μm to 500 μm.

[Front Panel] When viewed from the visually recognizable side, the front surface plate 1 constitutes the outermost surface of the optical laminate. As long as the front surface plate 1 is a plate-shaped body capable of transmitting light, the material and thickness are not limited, and may include only one layer, or two or more layers. As an example, a resin film, a glass film, etc. are mentioned. The front surface plate preferably has a resin film. The number of resin films the front surface plate has is preferably one. The front surface plate 1 may be a laminate of a resin film and a glass film.

The thickness of the front surface plate 1 may be, for example, 30 μm to 200 μm, preferably 50 μm to 150 μm, and more preferably 50 μm to 100 μm.

When the front surface plate 1 has a resin film, examples of the material include acrylic resins such as polymethyl (meth)acrylate and polyethyl (meth)acrylate; polyethylene, polypropylene, and polymethylmethacrylate; Polyolefin resins such as pentene and polystyrene; cellulosic resins such as triacetyl cellulose, acetyl cellulose butyrate, acryl cellulose, butyl cellulose, and acetyl acryl cellulose; Polyvinyl resins such as ethylene-vinyl acetate copolymers, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, and polyvinyl acetal; tungsten resins such as polyether and polyether; polyether ketone and polyether Ketone-based resins such as ether ketones; polyetherimides; polycarbonate-based resins; polyester-based resins; polyimide-based resins; polyimide-based resins; and polyamide-based resins. These polymers can be used alone or in combination of two or more. Among them, from the viewpoint of improving strength and transparency, it is preferable to use a polycarbonate resin, a polyester resin, a polyimide resin, a polyimide resin, or a polyimide resin.

The thickness of the resin film may be, for example, 10 μm to 100 μm, preferably 20 μm to 70 μm, and more preferably 30 μm to 60 μm.

The glass transition temperature (°C) of the resin film of the front surface plate 1 is preferably 200°C or higher and 500°C or lower, more preferably 300°C or higher and 500°C or lower.

The absorbance of the resin film of the front surface plate 1 with respect to light having a wavelength of 9.3 μm is preferably 0.01 or more and 1.0 or less, and more preferably 0.01 or more and 0.5 or less.

The front surface plate 1 may be a film in which a hard coat layer is provided on at least one surface of a resin film to further increase the hardness. The hard coat layer can be formed on one side of the resin film or on both sides. By providing a hard coat layer, a front surface plate with improved hardness and scratch resistance can be made. The hard coat layer is, for example, a cured layer of ultraviolet curable resin. Examples of ultraviolet curable resins include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. In order to increase the hardness, the hard coat layer may contain additives. The additives are not limited, and examples include inorganic fine particles, organic fine particles, or a mixture of these.

It is preferable to form an abrasion layer on the visible side of the hard coat layer to improve abrasion resistance or prevent contamination by sebum or the like. The front surface plate may have an abrasion resistant layer, and the abrasion resistant layer may be a layer constituting the visually recognizable side surface of the front surface plate. The abrasion resistant layer contains a structure derived from a fluorine compound. The fluorine compound is preferably a compound having a silicon atom and having an alkoxy group or a halogen-like hydrolyzable group in the silicon atom. The hydrolyzable group undergoes a dehydration condensation reaction to form a coating film, and it reacts with the active hydrogen on the surface of the substrate to improve the adhesion of the wear layer. In addition, when the fluorine compound has a perfluoroalkyl group or perfluoropolyether structure, it can impart water repellency, which is preferable. Particularly preferred is a fluorine-containing polyorganosiloxane compound having a perfluoropolyether structure and a long-chain alkyl group with a carbon number of 4 or more. It is also preferable to use two or more kinds of compounds as the fluorine compound. As the fluorine compound contained more preferably, a fluorine-containing organosiloxane compound containing an alkylene group having a carbon number of 2 or more and a perfluoroalkylene group.

The thickness of the wear layer is, for example, 1 nm to 20 nm. In addition, the abrasion resistant layer has water repellency, and the water contact angle is, for example, about 110° to 125°. The contact angle hysteresis and the sliding angle measured by the sliding method are about 3°-20° and 2°-55°, respectively. Furthermore, within a range that does not hinder the effects of the present invention, the wear layer may also contain silanol condensation catalysts, antioxidants, rust inhibitors, ultraviolet absorbers, light stabilizers, antifungal agents, antibacterial agents, and biological adhesion. Various additives such as inhibitors, deodorants, pigments, flame retardants, and antistatic agents.

It is also possible to provide a primer layer between the wear-resistant layer and the hard coat layer. As the primer, for example, there are primers such as ultraviolet curing type, thermosetting type, moisture curing type, or two-component curing type epoxy compound. In addition, as the primer, polyamic acid can be used, and a silane coupling agent is also preferably used. The thickness of the primer layer is, for example, 0.001 μm to 2 μm.

As a method of obtaining a front surface plate including a wear-resistant layer and a hard coat layer, it can be formed by applying a primer on the hard coat layer as necessary, and then drying and hardening to form a primer layer. Then, a composition containing a fluorine compound (composition for coating a wear layer) is applied and dried. Examples of coating methods include dip coating, roll coating, bar coating, spin coating, spray coating, die coating, and gravure coater methods. In addition, it is also preferable to perform hydrophilization treatment such as plasma treatment, corona treatment, or ultraviolet treatment on the coating surface before applying the primer or the composition for coating the wear layer. The laminate can also be directly laminated on the front surface plate, or it can be laminated on another transparent substrate by using an adhesive or adhesive to bond it to the front surface plate.

When the front surface plate 1 has a glass plate, it is preferable to use tempered glass for a display as a glass plate. The thickness of the glass plate may be, for example, 10 μm or more and 500 μm or less, or 20 μm or more and 100 μm or less. By using a glass plate, the front surface plate 1 having excellent mechanical strength and surface hardness can be constructed.

In the case of using the optical laminate for a display device, the front surface plate 1 may have a function as a window film in the display device. The front surface plate 1 may further have a function as a touch sensor, a blue light blocking function, a viewing angle adjustment function, and the like.

[Polarizing layer] The polarizing layer may be, for example, a linear polarizing plate, a circular polarizing plate (including an elliptical polarizing plate), or the like. The circular polarizer includes a linear polarizer and a retardation film. The circular polarizing plate can absorb external light reflected in the image display device, and therefore, can provide the optical laminate with a function as an anti-reflection film.

The polarizing layer preferably has a resin film. The number of resin films included in the polarizing layer is preferably one or two, and more preferably one.

[Straight Polarizing Plate] The linear polarizing plate has a function of selectively transmitting linearly polarized light in one direction from non-polarized light such as natural light. The linear polarizing plate may include a stretched film or a stretched layer to which a dichroic dye is adsorbed, a liquid crystal layer, etc., as a polarizer. The liquid crystal layer includes a cured product of a polymerizable liquid crystal compound and a dichroic dye, and the dichroic dye is The polymerizable liquid crystal compound is dispersed and aligned in the cured product. A linear polarizing plate using a liquid crystal layer as a polarizer has no limitation in the bending direction as compared with a stretched film or stretched layer to which a dichroic dye is adsorbed, so it is preferable.

(As a polarizer for a stretched film or stretched layer with dichroic pigments adsorbed) Polarizers, which are stretched films with dichroic pigments adsorbed, can usually be manufactured through the following steps: a step of uniaxially stretching a polyvinyl alcohol-based resin film; The step of dyeing the resin film to adsorb the dichroic pigment; the step of treating the polyvinyl alcohol resin film with the dichroic pigment adsorbed with the boric acid aqueous solution; and the step of washing with water after the treatment with the boric acid aqueous solution.

The thickness of the polarizer is generally 30 μm or less, preferably 18 μm or less, and more preferably 15 μm or less. Reducing the thickness of the polarizer is beneficial to making the polarizer 103 thinner. The thickness of the polarizer is usually 1 μm or more, for example, it may be 5 μm or more. In the case where the thickness of the polarizer is 10 μm or more, the polarizer is included in the resin film of formula (1).

The polyvinyl alcohol-based resin is obtained by saponifying a polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and other monomers that can be copolymerized therewith can also be used. As other monomers that can be copolymerized with vinyl acetate, for example, unsaturated carboxylic acid-based compounds, olefin-based compounds, vinyl ether-based compounds, unsaturated sulfonic acid-based compounds, and (meth)propylene having an ammonium group can be cited. Amide-based compounds.

The degree of saponification of the polyvinyl alcohol-based resin is generally about 85 mol% or more and 100 mol% or less, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and polyvinyl formal, polyvinyl acetal, etc. modified by aldehydes may also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 or more and 10,000 or less, preferably 1,500 or more and 5,000 or less.

A polarizer as a stretched layer to which a dichroic dye is adsorbed can usually be manufactured through the following steps: a step of applying a coating solution containing the above-mentioned polyvinyl alcohol-based resin on a base film, and a single layer of the resulting laminated film The step of axial stretching, the step of dyeing the polyvinyl alcohol resin layer of the monoaxially stretched laminate film with a dichroic dye, and adsorbing the dichroic dye to prepare a polarizer, using a boric acid aqueous solution The step of treating the film on which the dichroic dye is adsorbed, and the step of washing with water after treatment with an aqueous boric acid solution. The base film used to form the polarizer can be used as a protective layer of the polarizer. If necessary, the base film can be peeled and removed from the polarizer. In the case where the base film is not removed by peeling, the base film may be a resin film of formula (1). The material and thickness of the base film may be the same as the material and thickness of the resin film described later.

The polarizer that is a stretched film or stretched layer to which a dichroic dye is adsorbed can be directly used as a linear polarizing plate, or it can be used as a linear polarizing plate by laminating a resin film on one or both sides. The thickness of the linear polarizing plate is preferably 2 μm or more and 40 μm or less.

Examples of the resin film include: cyclic polyolefin resin film; cellulose acetate resin film containing resins such as triacetyl cellulose and diacetyl cellulose; containing polyethylene terephthalate and polyethylene naphthalate Polyester resin films of resins such as ethylene glycol ester and polybutylene terephthalate; polycarbonate resin films; (meth)acrylic resin films; polypropylene resin films and other films known in the art . The polarizer and the protective layer can be laminated via the bonding layer described later.

The thickness of the resin film is, for example, 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, still more preferably 40 μm or less, still more preferably 30 μm or less, and usually 10 μm or more. From the standpoint of the absorptivity of, it is preferably 15 μm or more.

The glass transition temperature (°C) of the resin film included in the polarizing layer 2 is preferably 100°C or higher and 300°C or lower, and more preferably 100°C or higher and 250°C or lower.

The absorbance of the resin film of the polarizing layer 2 with respect to light having a wavelength of 9.3 μm is preferably 0.01 or more and 1.0 or less, and more preferably 0.01 or more and 0.5 or less.

A hard coat layer can be formed on the resin film. The hard coat layer can be formed on one side of the resin film or on both sides. By providing a hard coat layer, a thermoplastic resin film with improved hardness and scratch resistance can be made. The hard coat layer can be formed in the same manner as the hard coat layer formed on the resin film.

(As a polarizer for the liquid crystal layer) The polymerizable liquid crystal compound used for forming the liquid crystal layer is a compound having a polymerizable reactive group and exhibiting liquid crystallinity. The polymerizable reactive group is a group that participates in the polymerization reaction, and is preferably a photopolymerizable reactive group. The photopolymerizable reactive group refers to a group that can participate in a polymerization reaction by a living radical or acid generated from a photopolymerization initiator. Examples of the photopolymerizable functional group include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, and oxa Cyclopropyl, oxetanyl, etc. Among them, propyleneoxy, methacryloxy, vinyloxy, oxetanyl, and oxetanyl are preferred, and propyleneoxy is more preferred. The type of the polymerizable liquid crystal compound is not particularly limited, and rod-shaped liquid crystal compounds, discotic liquid crystal compounds, and mixtures thereof can be used. The liquid crystal properties of the polymerizable liquid crystal compound may be thermotropic liquid crystal or lyotropic liquid crystal, and may be nematic liquid crystal or smectic liquid crystal as a phase sequence structure.

The dichroic dye used in the polarizer as the liquid crystal layer is preferably one having an absorption maximum wavelength (λMAX) in the range of 300 nm to 700 nm. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes. Among them, azo dyes are preferred. Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrasazo dyes, and stilbene azo dyes, and bisazo dyes and trisazo dyes are preferred. The dichroic dye may be singly or in combination of two or more, preferably three or more in combination. In particular, it is more preferable to combine three or more azo compounds. A part of the dichroic dye may have a reactive group, and may also have liquid crystallinity.

As the polarizer of the liquid crystal layer, for example, a composition for forming a polarizer containing a polymerizable liquid crystal compound and a dichroic dye can be applied to an alignment film formed on a base film, and the polymerizable liquid crystal compound is polymerized to make it Hardened and formed. The base film used to form the polarizer can be used as a protective layer of the polarizer. The material and thickness of the base film may be the same as the material and thickness of the resin film.

As a composition for forming a polarizer containing a polymerizable liquid crystal compound and a dichroic dye, and a method for manufacturing a polarizer using the composition, Japanese Patent Laid-Open No. 2013-37353 and Japanese Patent Laid-Open 2013-33249 can be exemplified No. and Japanese Patent Laid-Open No. 2017-83843, etc. In addition to the polymerizable liquid crystal compound and the dichroic dye, the composition for forming a polarizer may further contain additives such as a solvent, a polymerization initiator, a crosslinking agent, a leveling agent, an antioxidant, a plasticizer, and a sensitizer. Only one kind of these components may be used, respectively, or two or more kinds may be used in combination.

The polymerization initiator that can be contained in the composition for forming a polarizer is a compound that can initiate a polymerization reaction of a polymerizable liquid crystal compound, and a photopolymerizable initiator is preferred in terms of being capable of initiating a polymerization reaction under lower temperature conditions. Specifically, photopolymerization initiators that can generate active radicals or acids by the action of light are exemplified. Among them, photopolymerization initiators that can generate free radicals by the action of light are preferred. The content of the polymerization initiator is preferably 1 part by mass or more and 10 parts by mass or less, and more preferably 3 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the total amount of the polymerizable liquid crystal compound. If it is within this range, the reaction of the polymerizable group proceeds sufficiently, and it is easy to stabilize the alignment state of the liquid crystal compound.

The thickness of the polarizer as the liquid crystal layer is usually 10 μm or less, preferably 0.5 μm or more and 8 μm or less, and more preferably 1 μm or more and 5 μm or less.

The polarizer as the liquid crystal layer can be used as a linear polarizing plate without peeling and removing the base film, or the base film may be peeled and removed from the polarizer and used as a linear polarizing plate. In the case where the base film is not removed by peeling, the base film may be a resin film of formula (1). The polarizer as a liquid crystal layer can also be used as a linear polarizer by forming a protective layer on one or both surfaces. As the protective layer, the resin film described above can be used.

Regarding the polarizer as the liquid crystal layer, in order to protect the polarizer, etc., an overcoat may be provided on one or both sides of the polarizer. The overcoat layer can be formed by coating a material (composition) for forming the overcoat layer on a polarizer, for example. Examples of materials constituting the overcoat layer include photocurable resins and water-soluble polymers. As the material constituting the overcoat layer, (meth)acrylic resin, polyvinyl alcohol resin, etc. can be used.

(Retardation film) The retardation film contained in the polarizing layer may include one retardation layer, or may be a laminate of two or more retardation layers. The retardation film is preferably laminated on the surface of the polarizer on the opposite side to the front surface plate side. The retardation film may have an overcoat to protect its surface, a base film that supports the retardation film, and the like. The retardation layer includes a λ/4 layer, and may further include at least any one of a λ/2 layer or a positive C layer. When the retardation layer includes a λ/2 layer, the λ/2 layer and the λ/4 layer are laminated in this order from the polarizer side. When the retardation layer includes a positive C layer, a λ/4 layer and a positive C layer may be laminated in order from the polarizer side, or a positive C layer and a λ/4 layer may be laminated in order from the polarizer side. The thickness of the retardation layer is, for example, 0.1 μm or more and 10 μm or less, preferably 0.5 μm or more and 8 μm or less, and more preferably 1 μm or more and 6 μm or less.

The retardation layer may include the resin film exemplified as the material of the protective layer, or may include a layer formed by curing a polymerizable liquid crystal compound. From the viewpoint of improving flexibility, the retardation layer is preferably a layer formed by curing a polymerizable liquid crystal compound. The retardation layer may further include an alignment film. The retardation layer may have a bonding layer for bonding the λ/4 layer and the λ/2 layer, and the λ/4 layer and the positive C layer.

When the polymerizable liquid crystal compound is cured to form a retardation layer, the retardation layer can be formed by applying a composition containing the polymerizable liquid crystal compound to a base film and curing it. An alignment film can be formed between the base film and the coating layer. The material and thickness of the base film may be the same as the material and thickness of the resin film. When the retardation layer is formed from a layer formed by curing the polymerizable liquid crystal compound, the retardation layer may be assembled in the optical laminate in the form of an alignment film and/or a base film. In the case where the base film is not removed by peeling, the base film may be a resin film in formula (1). The retardation layer can be bonded to the linear polarizing plate via the bonding layer.

[Touch sensor layer] Viewed from the visual recognition side, the touch sensor layer 3 is located at the lowermost layer. The touch sensor layer 3 has a transparent conductive layer and a resin film. The number of resin films of the touch sensor layer 3 is preferably one. The touch sensor layer 3 may include a transparent conductive layer 31 and a resin film 32 in order from the front surface plate side. The touch sensor layer 3 may also include a resin film 32 and a transparent conductive layer 31 in order from the front surface plate side. In addition to the transparent conductive layer 31 and the resin film 32, the touch sensor layer 3 may also include a separation layer, a bonding layer, and a protective layer.

As the touch sensor layer 3, as long as it is a sensor that can detect the position touched on the front panel 1 and has a transparent conductive layer 31 and a resin film 32, the detection method is not limited. . As the detection method of the touch sensor layer, a resistive film method, an electrostatic capacitance method, an optical sensor method, an ultrasonic method, an electromagnetic induction coupling method, a surface acoustic wave method, etc. can be cited. Among them, in terms of low cost, fast response speed, and thin film, it is preferable to use an electrostatic capacitive touch sensor layer.

The touch sensor layer 3 preferably includes a resin film 32 and a transparent conductive layer 31 provided on the surface of the resin film 32 on the bonding layer side. In the configuration in which the transparent conductive layer 31 is provided on the surface of the resin film 32, the resin film 32 and the transparent conductive layer 31 may be in contact with each other (for example, a touch sensor layer manufactured by the first method described later) It may also be a configuration in which the resin film 32 and the transparent conductive layer 31 are not in contact with each other (for example, a touch sensor layer manufactured by the second method described later). In addition to the resin film 32 and the transparent conductive layer 31, the touch sensor layer 3 may additionally include a bonding layer, a separation layer, a protective layer, and the like. Examples of the bonding layer include an adhesive layer and an adhesive layer.

An example of the capacitive touch sensor layer includes a resin film, a transparent conductive layer for position detection provided on the surface of the resin film, and a touch position detection circuit. In a display device provided with an optical laminate including an electrostatic capacitive touch sensor layer, when the surface of the front surface plate 1 is touched, at the touched point, the transparent conductive layer is formed by the electrostatic capacitance of the human body. Grounded. The touch position detection circuit detects the grounding of the transparent conductive layer, thereby detecting the touched position. By having a plurality of transparent conductive layers separated from each other, more detailed position detection can be performed.

The transparent conductive layer may be a transparent conductive layer containing metal oxides such as indium tin oxide (ITO), or a metal layer containing metals such as aluminum, copper, silver, gold, or alloys of these.

The separation layer may be a layer formed on a substrate such as glass to separate the transparent conductive layer formed on the separation layer from the substrate together with the separation layer. The separation layer is preferably an inorganic layer or an organic layer. Examples of the material forming the inorganic layer include silicon oxide. As a material for forming the organic layer, for example, a (meth)acrylic resin composition, an epoxy resin composition, a polyimide resin composition, and the like can be used.

The touch sensor layer 3 may include a protective layer in contact with the transparent conductive layer 31 to protect the conductive layer. The protective layer includes at least one of an organic insulating film and an inorganic insulating film, and the film can be formed by a spin coating method, a sputtering method, an evaporation method, or the like.

The touch sensor layer 3 can be manufactured in the following manner, for example. In the first method, first, the resin film 32 is laminated on the glass substrate via lamination. A patterned transparent conductive layer 31 is formed on the resin film 32 by photolithography. By heating, the glass substrate and the resin film 32 are separated, so that the touch sensor layer 3 including the transparent conductive layer 31 and the resin film 32 is obtained.

In the second method, a separation layer is first formed on a glass substrate, and a protective layer is formed on the separation layer as necessary. A patterned transparent conductive layer 31 is formed on the separation layer (or protective layer) by photolithography. A peelable protective film is laminated on the transparent conductive layer 31, the transparent conductive layer 31 to the separation layer are transferred, and the glass substrate is separated. The resin film 32 is bonded to the separation layer through the bonding layer, and the peelable protective film is peeled off, thereby obtaining a touch sensor having a transparent conductive layer 31, a separation layer, a bonding layer, and a resin film 32 in this order Layer 3.

As the resin film 32 of the touch sensor layer, triacetyl cellulose, polyethylene terephthalate, polyethylene naphthalate, polyolefin, polycycloolefin, polycarbonate, Polyether, polyarylate, polyimide, polyamide, polystyrene, acrylic and other resin films.

From the viewpoint of easy formation of an optical laminate having excellent bending resistance, the thickness of the resin film 32 of the touch sensor layer is preferably 50 μm or less, and more preferably 30 μm or less. From the viewpoint of improving the absorption rate of the laser, the thickness of the resin film 32 included in the touch sensor layer is, for example, 10 μm or more, preferably 20 μm or more.

The glass transition temperature (°C) of the resin film included in the touch sensor layer 3 is preferably 100°C or higher and 300°C or lower, and more preferably 100°C or higher and 250°C or lower.

The absorbance of the resin film of the touch sensor layer 3 to light with a wavelength of 9.3 μm is preferably 0.01 or more and 1.0 or less, more preferably 0.01 or more and 0.5 or less, and may also be 0.08 or more and 0.3 or less.

[Laminated layer] The bonding layer may be a layer containing an adhesive or an adhesive. The bonding layer is not included in the resin film of formula (1). Each bonding layer may include the same material or different materials. The bonding layer in which the front surface plate 1 and the polarizing layer 2 are laminated, and the bonding layer in which the polarizing layer 2 and the touch sensor layer 3 are laminated are preferably an adhesive layer. The bonding layer in which the transparent conductive layer 31 and the resin film 32 are laminated is preferably an adhesive layer.

The adhesive layer may include an adhesive composition mainly composed of (meth)acrylic, rubber, urethane, ester, silicone, and polyvinyl ether resins. Among them, an adhesive composition using a (meth)acrylic resin excellent in transparency, weather resistance, heat resistance, etc., as a base polymer is preferred. The adhesive composition can be an active energy ray hardening type or a heat hardening type.

As the (meth)acrylic resin (base polymer) used in the adhesive composition, for example, butyl (meth)acrylate, ethyl (meth)acrylate, and isooctyl (meth)acrylate are preferably used. A polymer or copolymer in which one or two or more of (meth)acrylates such as esters and 2-ethylhexyl (meth)acrylate are used as monomers. Polar monomers can be copolymerized in the raw polymer. Examples of polar monomers include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, and N, N (meth)acrylic acid. -A monomer having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, etc. like dimethylaminoethyl and glycidyl (meth)acrylate.

The adhesive composition may contain a crosslinking agent. Examples of the crosslinking agent include: a metal ion having a valence of two or more and forming a carboxylic acid metal salt with a carboxyl group; a polyamine compound forming an amide bond with a carboxyl group; a polyepoxy compound or Polyols, which form ester bonds with carboxyl groups; polyisocyanate compounds, which form amide bonds with carboxyl groups. Among them, polyisocyanate compounds are preferred.

The adhesive composition may contain fine particles, beads (resin beads, glass beads, etc.), glass fibers, resins other than raw polymers, tackifiers, fillers (metal powder or other inorganic powders, etc.) for imparting light scattering properties. , Antioxidants, ultraviolet absorbers, dyes, pigments, colorants, defoamers, anti-corrosion agents, photopolymerization initiators and other additives.

The adhesive layer can be formed by coating the organic solvent diluent of the adhesive composition on the substrate and drying it.

The storage elastic coefficient of the adhesive layer at a temperature of 25°C is preferably 0.005 MPa to 1.0 MPa, more preferably 0.01 MPa to 0.5 MPa, and still more preferably 0.01 MPa to 0.2 MPa. The storage elasticity coefficient can be measured using a viscoelasticity measuring device (MCR-301, Anton Paar). It is possible to laminate multiple adhesive layers with a thickness of 150 μm and bond them to the glass plate, and then, in the state of bonding with the measuring wafer, in the temperature range of -20°C to 100°C, at a frequency of 1.0 Hz and a deformation amount of 1 %, and the temperature rise rate is measured under the conditions of 5°C/min.

As the adhesive, for example, it can be formed by combining one or two or more of water-based adhesives, active energy ray-curable adhesives, and the like. As the water-based adhesive, for example, a polyvinyl alcohol-based resin aqueous solution, an aqueous two-component urethane-based emulsion adhesive, and the like can be cited. Active energy ray curable adhesives are adhesives that are cured by irradiating active energy rays such as ultraviolet rays. Examples include adhesives containing polymerizable compounds and photopolymerizable initiators, adhesives containing photoreactive resins, and adhesives containing adhesives. Adhesives for resins and photoreactive crosslinking agents. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and those derived from these monomers. Body oligomers and so on. Examples of the photopolymerization initiator include compounds containing substances that generate active species such as neutral radicals, anionic radicals, and cationic radicals by irradiation with active energy rays such as ultraviolet rays.

When the bonding layer is an adhesive layer, the thickness of the adhesive layer is preferably 1 μm or more and 50 μm or less, more preferably 5 μm or more and 30 μm or less. When the bonding layer is an adhesive layer, the thickness of the adhesive layer is preferably 0.01 μm or more and 5 μm or less, more preferably 0.1 μm or more and 3 μm or less.

[Method of manufacturing optical laminate] The optical laminate of the present invention is manufactured by combining the front surface plate, the polarizing layer, and the touch sensor layer using an adhesive layer. As a method of bonding each layer, it is sufficient to form a bonding layer on the surface of one layer to be bonded and then to laminate the other layer, or to form a bonding layer on the surfaces to be bonded of both layers, and then to paste The layers are joined to each other. The method of forming the adhesive layer on the surface of the layer to be bonded can be formed by using an adhesive composition as described above, or a sheet-shaped adhesive that can be processed independently can be prepared and formed by attaching it to the surface.

After bonding each layer, the optical laminate can be cut into a predetermined shape by laser. In the cut optical laminate, it is not easy to produce micro cracks on the resin film included in the touch sensor layer. Therefore, an optical laminate and a display device excellent in flexibility can be obtained.

As the laser, for example, a laser emitting a wavelength in the range of 200 nm to 11 μm is used. The laser can be a continuous wave (CW) laser or a pulsed laser. Cracks on the resin film included in the touch sensor layer are likely to occur when the optical laminate is cut by a CW laser. Therefore, the present invention is particularly useful when a CW laser is used. Examples of laser types include _{gas lasers such as CO 2} lasers, solid lasers such as Yttrium Aluminum Garnet (Yttrium Aluminum Garnet, YAG) lasers, and semiconductor lasers. In terms of easily adapting to the absorption region of the optical laminate, a CO ₂ laser is preferred.

The laser light may be incident from the front surface plate 1 side of the optical laminate (from the side that is visually recognized), and may also be incident from the side of the touch sensor layer 3 (the side opposite to the side that is visually recognized). From the viewpoint of improving the bending resistance, it is preferable to cause the laser light to enter from the front surface plate 1 side. That is, the manufacturing method of the optical laminated body may include the step of making laser light enter from the visual recognition side, and cutting into a predetermined shape by laser.

The irradiation conditions (output conditions, moving speed) of the laser light can be any appropriate conditions according to the laser used. In the case of using a CO ₂ laser, the output of the laser is preferably 2 W or more and 20 W or less, more preferably 5 W or more and 15 W or less, and still more preferably 7 W or more and 12 W or less. The moving speed of the laser light is preferably 50 mm/sec or more and 1000 mm/sec or less, more preferably 100 mm/sec or more and 500 mm/sec or less, and still more preferably 250 mm/sec or more and 400 mm/sec or less. The optical laminate can be cut by one irradiation, and the optical laminate can also be cut by multiple irradiations.

The energy of the laser light irradiated by scanning of a unit length (hereinafter, sometimes referred to as irradiation energy.) is preferably 1 mJ/mm or more, more preferably 10 mJ/mm or more, and still more preferably 25 mJ/mm or more. The upper limit of the irradiation energy is not particularly limited. For example, it is 1000 mJ/mm or less, may be 500 mJ/mm or less, or may be 100 mJ/mm or less.

In the case where the laser light is condensed by the lens, the focus of the laser light can be aimed at the surface on the front surface plate 1 side of the optical laminate, and can also be aimed at the touch sensor layer 3. The spot size of the laser light can be 5 μm or more and 100 μm or less, and it can be 10 μm or more and 70 μm or less. The depth of focus (DOF) of the lens can be 10 μm or more and 500 μm or less, and it can be 100 μm or more and 300 μm or less.

[Display device] The optical laminate can be arranged on the display surface of the display panel, for example, to constitute a display device. The optical laminate is particularly preferably used for the display surface of a flexible display panel. FIG. 2 is a cross-sectional view showing an example of the structure of the display device of the present invention. The display device 200 has an optical laminate 100 and a display panel 5 arranged on the front surface (visibility side) thereof. The optical laminate 100 and the display panel 5 are laminated by the bonding layer 4. The bonding layer in which the optical laminate and the display panel are laminated may be an adhesive layer. The display panel may be configured to be foldable with the visually recognized side surface as the inner side, or may be configured to be able to be wound. Specific examples of the display panel include liquid crystal display elements, organic electro-luminescence (EL) display elements, inorganic EL display elements, plasma display elements, and field emission display elements.

The display device 200 can be used as mobile devices such as smart phones, input panels, televisions, digital photo frames, electronic billboards, measuring instruments or measuring instruments, office equipment, medical equipment, computer equipment, and the like. [Example]

Hereinafter, the present invention will be explained in more detail with examples, but the present invention is not limited by these examples. In this embodiment, unless otherwise specified, the unit "part" of the ratio of the compounded substance is the weight basis.

[Measurement method of glass transition temperature] The glass transition temperature was measured with a differential scanning calorimetry device (Q-1000 manufactured by TA Instruments (Instruments)). In a nitrogen atmosphere, heat up the 2 mg～3 mg sample from 30°C to 250°C at a rate of 10°C/min, then lower the temperature from 250°C to 50°C at a rate of 10°C/min, and then at a rate of 10°C/min The rate of heating from 50 ℃ to 250 ℃. The glass transition temperature was obtained from the differential scanning calorimetry measurement during the second temperature increase.

[Method of measuring absorbance] The absorbance of light with a wavelength of 9.3 μm was measured using a Fourier transform infrared spectrophotometer (FT/IR-6300 manufactured by JASCO Corporation).

[Front Panel 1] As the front surface plate 1, one having a hard coat layer formed on one surface of a polyimide (PI) film is used. The PI film was prepared in accordance with Example 9 of Japanese Patent Application Laid-Open No. 2018-119141. The thickness of the polyimide film is 50 μm, and the thickness of the hard coat layer is 10 μm. The glass transition temperature of this polyimide film was 390°C. The absorbance of this polyimide film to light with a wavelength of 9.3 μm was 0.04.

[Front surface plate 2] As the front surface plate 2, a polyethylene terephthalate (PET) film is used. The PET film is SH34 manufactured by SKC Corporation. The thickness of the PET film is 23 μm. The glass transition temperature of this PET film was 114°C. The absorbance of this PET film to light with a wavelength of 9.3 μm was 0.18.

[Circular Polarizing Plate] An alignment film is formed on one surface of the triacetyl cellulose (Triacetyl Cellulose, TAC) film. A composition containing a polymerizable liquid crystal compound and a dichroic dye is coated on the alignment film. The coating film is aligned and cured to obtain a polarizer. Coating ultraviolet curable resin on the polarizer. The coating film is hardened to form an outer coating. In this way, a linear polarizing plate is obtained. The thickness of the TAC film is 25 μm, the thickness of the polarizer is 2.5 μm, and the thickness of the outer coating is 1.0 μm. The TAC film is KC2UAW manufactured by Konica Minolta Co., Ltd. The glass transition temperature of this TAC film was 160°C. The absorbance of this TAC film to light with a wavelength of 9.3 μm was 0.135.

The λ/4 layer including the layer formed by curing the polymerizable liquid crystal compound and the positive C laminate layer including the layer formed by curing the polymerizable liquid crystal compound are laminated by the acrylic adhesive layer to obtain a retardation film. The thickness of the λ/4 layer is 2 μm, the thickness of the positive C layer is 3 μm, and the thickness of the acrylic adhesive layer is 5 μm.

The linear polarizing plate and the retardation film are laminated by the acrylic adhesive layer to obtain a circular polarizing plate. The thickness of the acrylic adhesive layer is 5 μm. The obtained circular polarizing plate is a laminate having a TAC film, a polarizer, an outer coating, an adhesive layer, a λ/4 layer, an adhesive layer, and a positive C layer in this order.

[Touch sensor layer 1] A separation layer is formed on the glass substrate. A patterned transparent conductive layer is formed on the separation layer by photolithography. A peelable protective film is laminated on the transparent conductive layer, transferred from the transparent conductive layer to the separation layer, and the glass substrate is separated. The polyarylate film and the separation layer are bonded via the adhesive layer, and the peelable protective film is peeled off. In this way, a touch sensor layer having a transparent conductive layer, a separation layer, an adhesive layer, and a polyarylate film in this order was obtained. The polyarylate film is M-2040H manufactured by Unitika Co., Ltd. The glass transition temperature (°C) of the polyarylate film and the absorbance of light with a wavelength of 9.3 μm are shown in Tables 1 to 2. The thickness of the polyarylate film is 25 μm.

[Touch sensor layer 2] The touch sensor layer 2 was produced in the same manner as the production of the touch sensor layer 1 except that the polyarylate film was changed to a polyethylene terephthalate (PET) film. The PET film is SH34 manufactured by SKC Corporation. The glass transition temperature (°C) of the PET film and the absorbance of light with a wavelength of 9.3 μm are shown in Tables 1 to 2. The thickness of the PET film is 23 μm.

[Touch sensor layer 3] The touch sensor layer 3 was produced in the same manner as the production of the touch sensor layer 1 except that the polyarylate film was changed to the acrylic film 1. The acrylic film 1 is GA-01 manufactured by LG Chem Co., Ltd. The glass transition temperature (°C) of the acrylic film 1 and the absorbance of light with a wavelength of 9.3 μm are shown in Tables 1 to 2. The thickness of the acrylic film 1 is 40 μm.

[Touch sensor layer 4] The touch sensor layer 4 was produced in the same manner as the production of the touch sensor layer 1 except that the polyarylate film was changed to the acrylic film 2. The acrylic film 2 is SAZMA manufactured by Konica Minolta Co., Ltd. The glass transition temperature (°C) of the acrylic film 2 and the absorbance of light with a wavelength of 9.3 μm are shown in Tables 1 to 2. The thickness of the acrylic film 2 is 20 μm.

[Touch sensor layer 5] Except that the polyarylate film is changed to the acrylic film 3, the touch sensor layer 5 is produced in the same manner as the production of the touch sensor layer 1. The acrylic film 3 is BR-77 manufactured by Mitsubishi Chemical Corporation. The glass transition temperature (°C) of the acrylic film 3 and the absorbance of light with a wavelength of 9.3 μm are shown in Tables 1 to 2. The thickness of the acrylic film 3 is 40 μm.

[Touch sensor layer 6] Except that the polyarylate film is changed to a cycloolefin resin ((cycloolefin polymer) Cycloolefin Polymer, COP) film, the touch sensor layer 6 is produced in the same manner as the production of the touch sensor layer 1. The COP film is ZF14-023 manufactured by ZEON Co., Ltd. of Japan. The glass transition temperature (°C) of the COP film and the absorbance of light with a wavelength of 9.3 μm are shown in Tables 1 to 2. The thickness of the COP film is 23 μm.

[Touch sensor layer 7] Except that the polyarylate film is changed to a polyimide (PI) film, the touch sensor layer 7 is produced in the same manner as the production of the touch sensor layer 1. This PI film is manufactured as follows.

In a nitrogen atmosphere, add 52 g (162.38 mmol) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and adjust the water content to 500 ppm of N in a 1L separable flask equipped with a stirring blade. , N-Dimethylacetamide (DMAc) 673.93 g, stirring at room temperature, while dissolving TFMB in DMAc. Next, 28.90 g (65.05 mmol) of 4,4′-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA) was added to the flask, and the mixture was stirred at room temperature for 3 hours. Then, 19.81 g (97.57 mmol) of terephthalic acid chloride (TPC) was added to the flask, and the mixture was stirred at room temperature for 1 hour. Then, 7.49 g (94.65 mmol) of pyridine and 14.61 g (143.11 mmol) of acetic anhydride were added to the flask, and after stirring at room temperature for 30 minutes, the temperature was raised to 70° C. with an oil bath, and the mixture was stirred for 5 hours to obtain a reaction liquid.

The obtained reaction liquid was cooled to room temperature, and was thrown into a large amount of methanol in a filamentous state, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 100°C to obtain a polyimide resin. In the obtained polyimide resin, DMAc was added so that the concentration might reach 15 mass %, and the polyimide imide varnish was produced.

Use an applicator to coat the obtained polyimide varnish on the smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name "A4100") so that the film thickness of the self-supporting film becomes 55 μm. It was dried at 50°C for 30 minutes and then at 140°C for 15 minutes to obtain a self-supporting film. The self-supporting film was fixed on a metal frame, and then dried in the atmosphere at 230°C for 30 minutes to obtain a PI film with a film thickness of 50 μm. The glass transition temperature (°C) of the PI film and the absorbance of light with a wavelength of 9.3 μm are shown in Tables 1 to 2.

[Example 1] The front surface plate 1, the circular polarizing plate, and the touch sensor layer 1 are mutually laminated via an acrylic adhesive layer to obtain the optical laminate shown in FIG. 1. The thickness of the acrylic adhesive layer was 25 μm. The number of resin films included in the optical laminate of Example 1 is three.

[Example 2 to Example 6, Comparative Example 1 to Comparative Example 2] Except that the front panel and the touch sensor layer were changed to those shown in Table 1 or Table 2, an optical laminate was produced in the same manner as in Example 1.

[Crack Evaluation] The optical laminate produced in each of the Examples and Comparative Examples was cut _{using CO 2 laser (LP Tech).} The laser is a CW laser. The vibration wavelength of this laser is 9.3 μm. The laser light is incident from the front panel side of the optical laminate (the side that is visually recognized) or from the side of the touch sensor layer (the side that is opposite to the visually recognized side), and is condensed by the lens. The spot size of the laser is 45.1 μm. The DOF of the lens is 239 μm. The number of laser light irradiation is once, that is, the optical laminated body is cut by full-cutting. The laser output, moving speed, and irradiation energy are shown in Table 1 or Table 2. An optical microscope was used to observe whether the resin film included in the touch sensor layer had microcracks.

[Evaluation of bending durability] A bending test was performed on the optical laminate that had no cracks after being cut by laser, and the bending durability was evaluated. As shown in Figure 3(a) and Figure 3(b), the two mounting tables 501 and 502 that can be moved separately are arranged with a gap C of 3 mm (a bending radius of 1.5 mm) so that the center in the width direction is located The optical laminate 100 is fixedly arranged so that the center of the gap C and the front surface plate is located on the upper side (FIG. 3( a )). Then, the two mounting tables 501 and 502 are rotated upward by 90 degrees with the position P1 and the position P2 as the center of the rotation axis, and a bending force is applied to the region of the optical laminate corresponding to the gap C of the mounting table (Figure 3(b)) ). After that, the two mounting tables 501 and 502 are returned to their original positions (Fig. 3(a) ). After completing the above series of operations, count the number of times the bending force is applied as one. The operation was repeated at a temperature of 25°C. In the area corresponding to the gap C between the mounting table 501 and the mounting table 502 of the optical layered body, the number of additional bending forces that caused a crack in the optical layered body was counted. The moving speed of the mounting table 501 and the mounting table 502 and the additional step of the bending force were set to the same conditions in the evaluation test of any optical laminate.

[Table 1] Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Front panel Material of resin film PI PI PI PI PI PI Absorbance a ₁ 0.04 0.04 0.04 0.04 0.04 0.04 Tg ₁ (℃) 390 390 390 390 390 390 Tg ₁ ×a ₁ 15.6 15.6 15.6 15.6 15.6 15.6 Circular polarizer Material of resin film TAC TAC TAC TAC TAC TAC Tg ₂ (℃) 160 160 160 160 160 160 Absorbance a ₂ 0.135 0.135 0.135 0.135 0.135 0.135 Tg ₂ ×a ₂ 21.6 21.6 21.6 21.6 21.6 21.6 Touch sensor layer Touch sensor layer No. 1 2 3 4 5 6 Material of resin film Polyarylate PET Acrylic film 1 Acrylic film 2 Acrylic film 3 COP Tg ₃ (℃) 237 114 125 122 80 133 Absorbance a ₃ 0.1 0.18 0.05 0.04 0.04 0.01 Tg ₃ ×a ₃ 23.7 20.52 6.25 4.88 3.2 1.33 Parameter A 60.9 57.72 43.45 42.08 40.40 38.53 Laser conditions Irradiation direction From the visual side From the visual side From the visual side From the visual side From the visual side From the visual side Output (W) 9 10 11 11 13 13 Moving speed (mm/sec) 320 320 320 320 320 320 Irradiation energy (mJ/m) 28 31 34 34 41 41 Whether there is a crack No more than 250,000 times No 250,000 times No 150,000 times No 130,000 times Have- Have- Bending durability

[Table 2] Example 5 Example 6 Front panel Material of resin film PI PET Absorbance a ₁ 0.04 0.18 Tg ₁ (℃) 390 114 Tg ₁ ×a ₁ 15.6 20.52 Circular polarizer Material of resin film TAC TAC Tg ₂ (℃) 160 160 Absorbance a ₂ 0.135 0.135 Tg ₂ ×a ₂ 21.6 21.6 Touch sensor layer Touch sensor layer No. 2 7 Material of resin film PET PI Tg ₃ (℃) 114 400 Absorbance a ₃ 0.18 0.17 Tg ₃ ×a ₃ 20.52 68 Parameter A 57.72 110.12 Laser conditions Irradiation direction From the opposite side of visual recognition From the visual side Output (W) 13 12 Moving speed (mm/sec) 320 320 Irradiation energy (mJ/m) 41 38 Whether there is a crack No 100,000 times No more than 250,000 times Bending durability

The "self-recognizable side" in the table refers to, for example, irradiating the laser in the direction from the front surface plate 1 to the touch sensor layer 3 in FIG. 1, and the "self-recognizable side" refers to, for example, in FIG. The laser is irradiated along the direction from the touch sensor layer 3 toward the front surface plate 1.

When the optical laminate having a parameter A of 41 or more and 1200 or less is cut into a predetermined shape by laser light, the resin film included in the touch sensor layer does not crack.

1: Front surface plate 2: Polarizing layer 3: Touch sensor layer 4: Laminated layer 5: Display panel 10: Resin film 11: Hard coating 20: Polarizer 21: Resin film 22: retardation film 31: Transparent conductive layer 32: Resin film 100: Optical laminate 200: display device 501, 502: Mounting table C: gap P1, P2: position

FIG. 1 is a cross-sectional view showing an example of the structure of the optical laminate of the present invention. FIG. 2 is a cross-sectional view showing an example of the structure of the display device of the present invention. (A) and (b) of FIG. 3 are schematic diagrams explaining the method of a bending test.

1: Front surface plate

2: Polarizing layer

3: Touch sensor layer

4: Laminated layer

10: Resin film

11: Hard coating

20: Polarizer

21: Resin film

22: retardation film

31: Transparent conductive layer

32: Resin film

100: Optical laminate

Claims (7)

An optical laminate, including a front surface plate, a polarizing layer, and a touch sensor layer, wherein the touch sensor layer has a transparent conductive layer and a resin film, and the parameters represented by the following formula (1) A is 41 or more and 1200 or less,

(1) In formula (1), Tg _i represents the glass transition temperature (℃) _{of the ith resin film contained in the optical laminate, and a i} represents the wavelength of the ith resin film contained in the optical laminate of 9.3 μm For the absorbance of light, n represents an integer of 1 or more and 5 or less. The optical laminate according to claim 1, wherein the touch sensor layer has the transparent conductive layer and the resin film in this order from the front surface plate side, and The glass transition temperature (°C) of the resin film is 100°C or more and 300°C or less, The absorbance of light with a wavelength of 9.3 μm of the resin film is 0.01 or more and 1.0 or less. The optical laminate according to claim 1 or 2, wherein the front surface plate has a resin film, and The glass transition temperature (°C) of the resin film is 200°C or more and 500°C or less, The absorbance of light with a wavelength of 9.3 μm of the resin film is 0.01 or more and 1.0 or less. The optical laminate according to any one of claims 1 to 3, wherein the polarizing layer has a resin film, and The glass transition temperature (°C) of the resin film is 100°C or more and 300°C or less, The absorbance of light with a wavelength of 9.3 μm of the resin film is 0.01 or more and 1.0 or less. The optical laminate according to any one of claims 1 to 4, wherein the front surface plate, the polarizing layer, and the touch sensor layer each include a resin film. A display device having the optical laminate according to any one of claim 1 to claim 5. A method of manufacturing an optical laminate, which is a method of manufacturing the optical laminate according to any one of Claims 1 to 5, which includes causing laser light to enter from the visual recognition side and cutting into a predetermined shape by laser A step of.

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