JP7369160B2 - optical laminate - Google Patents

Description

The present invention relates to an optical laminate.

In an optical laminate such as a polarizing plate, the thickness of each layer can be adjusted depending on desired characteristics. Therefore, the thickness is appropriately measured during the manufacturing process. As a method for measuring the thickness, optical interference film thickness measurement is used because continuous measurement is possible (for example, Patent Document 1). However, there is a problem in that the thickness cannot be measured using the optical interference film thickness measurement method in a laminate in which the difference in refractive index of each layer is small. Although thickness can be measured using a scanning electron microscope (SEM) or a transmission electron microscope (TEM), it takes time to measure the thickness. Therefore, there is a problem that the yield rate decreases in the manufacturing process of the optical laminate.

JP2007-086511A

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to provide an optical laminate that can suppress variations in optical properties and can be manufactured with high yield. It is in.

（式中、Ｘはビニル基、（メタ）アクリル基、スチリル基、（メタ）アクリルアミド基、ビニルエーテル基、エポキシ基、オキセタン基、ヒドロキシル基、アミノ基、アルデヒド基、および、カルボキシル基からなる群より選択される少なくとも１種の反応性基を含む官能基を表し、Ｒ^１およびＲ^２はそれぞれ独立して、水素原子、置換基を有していてもよい脂肪族炭化水素基、置換基を有していてもよいアリール基、または、置換基を有していてもよいヘテロ環基を表し、Ｒ^１およびＲ^２は互いに連結して環を形成してもよい）。 The optical laminate of the embodiment of the present invention has a first layer having refractive index anisotropy and a second layer that is optically isotropic, and the second layer has a wavelength of 365 nm. Contains a luminescent material whose molar extinction coefficient is 10,000 L/mol·cm or more. The difference between the in-plane average refractive index at a wavelength of 550 nm of the first layer and the in-plane average refractive index at a wavelength of 550 nm of the second layer is 0.3 or less, and the difference between the thickness of the first layer and the second layer The difference between the thickness and the thickness is 6 μm or less.
In one embodiment, the first layer is a polarizer.
In one embodiment, the second layer has a thickness of less than 1 μm.
In one embodiment, the luminescent material is at least one selected from coumarin compounds and derivatives thereof.
In one embodiment, the second layer is a solidified layer or a hardened layer of a coating film of an organic solvent solution, and the organic solvent solution contains 0.1 parts by weight to 0 parts by weight of the luminescent material based on 100 parts by weight of the resin. Contains .5 parts by weight.
In one embodiment, the resin polymerizes more than 50 parts by weight of an acrylic monomer and more than 0 parts by weight and less than 50 parts by weight of a comonomer represented by formula (1). Including polymers obtained by:

(wherein, Represents a functional group containing at least one selected reactive group, and R ¹ and R ² each independently represent a hydrogen atom, an aliphatic hydrocarbon group that may have a substituent, or a functional group containing a substituent. represents an aryl group which may have a substituent or a heterocyclic group which may have a substituent, and R ¹ and R ² may be connected to each other to form a ring).

According to embodiments of the present invention, an optical laminate that can suppress variations in optical properties and can be manufactured with high yield is provided. The optical laminate of the embodiment of the present invention has a small difference in refractive index and thickness of each layer, and even in cases where it is difficult to measure the film thickness by a simple method such as optical interference film thickness measurement, the optical laminate can be easily filmed. Thickness can be measured. Therefore, variations in optical properties due to variations in thickness can be suppressed. As a result, variations in optical properties can be suppressed and optical laminates can be manufactured with high yield.

FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.

Preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

A. Outline of optical laminate FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. The illustrated optical laminate 100 includes a first layer 10 having optical anisotropy and an optically isotropic second layer 20 laminated on one surface of the first layer. have The difference between the in-plane average refractive index at a wavelength of 550 nm of the first layer 10 and the in-plane average refractive index at a wavelength of 550 nm of the second layer is 0.3 or less, and the difference between the thickness of the first layer and the second layer The difference between the thickness and the thickness is 6 μm or less. The second layer 20 includes a luminescent material (hereinafter also referred to as luminescent material) having a molar extinction coefficient of 10000 L/mol·cm or more at a wavelength of 365 nm. Therefore, the difference between the in-plane average refractive index at a wavelength of 550 nm of the first layer and the in-plane average refractive index at a wavelength of 550 nm of the second layer is 0.3 or less, and the difference between the thickness of the first layer and the second layer is 0.3 or less. Even when it is difficult to measure the film thickness by optical interference, such as when the difference between the layer thicknesses is 6 μm or less, the film thickness can be easily measured. Specifically, when irradiated with light having a specific wavelength, a difference occurs in the amount of light emitted between the first layer and the second layer. For example, when the optical laminate is irradiated with light perpendicularly, the amount of light emitted from the second layer is proportional to the luminescent material content of the second layer, that is, the thickness of the second layer. Therefore, after measuring the luminescence amount of the second layer having an arbitrary thickness in advance, the accurate thickness is measured by, for example, SEM or TEM, and a calibration curve showing the relationship between the thickness of the second layer and the luminescence amount is created. Therefore, by measuring only the amount of light emitted from the second layer in-line at the manufacturing site, it is possible to accurately measure the thickness of the second layer.

In one embodiment, first layer 10 is a polarizer. Therefore, the optical laminate 100 is a polarizing plate in one embodiment. In one embodiment, second layer 20 is a resin layer containing a luminescent material. In one embodiment of the invention, the second layer is a solidified or cured layer of an organic solvent solution coating. In one embodiment, second layer 20 may function as a protective layer.

The optical laminate 100 may further include any appropriate layer other than the protective layer 20 depending on the purpose. Other layers include any suitable layers used in optical laminates. Examples include a protective layer, a retardation layer, a light diffusion layer, an antireflection layer, a reflective polarizer, and the like. Other layers may be laminated on the first layer 10 side or on the second layer 20 side. It may also include a plurality of other layers.

The difference between the in-plane average refractive index of the first layer and the in-plane average refractive index of the second layer is 0.3 or less, preferably 0.2 or less, more preferably 0.1 or less, and even more preferably It is 0.05 or less. The difference between the in-plane average refractive index of the first layer and the in-plane average refractive index of the second layer may be zero (even if the refractive indexes are the same). Even when the difference between the in-plane average refractive index of the first layer and the in-plane average refractive index of the second layer is small as described above, the optical laminate of the embodiment of the present invention can be easily formed into a film. The thickness can be measured, and an optical laminate with small variations in optical properties can be manufactured at a high yield. The in-plane average refractive index can be measured using a prism coupler, for example.

The difference between the thickness of the first layer and the thickness of the second layer is 6 μm or less. The difference between the thickness of the first layer and the thickness of the second layer may be zero (or the thickness may be the same). In the optical laminate of the embodiment of the present invention, even if the difference between the thickness of the first layer and the thickness of the second layer is within the above range, the film thickness can be easily measured, and the optical laminate can be easily measured. Optical laminates with small variations in properties can be manufactured with high yield. The thickness of each layer can be measured by any suitable method. For example, the thickness of the first layer can be determined by determining the thickness of the second layer using a method using a calibration curve as described above, and subtracting the thickness of the second layer from the total thickness. .

B. First Layer The first layer is a layer having refractive index anisotropy. Any suitable layer having refractive index anisotropy can be used as the first layer. The first layer may have refractive index anisotropy in the in-plane direction, may have refractive index anisotropy in the thickness direction, and may have refractive index anisotropy in the in-plane direction and in the thickness direction. It may have. In one embodiment, the first layer has refractive index anisotropy in the in-plane direction. Examples of the first layer include a polarizer, a retardation layer, and the like. In one embodiment, the first layer is a polarizer.

The in-plane average refractive index of the first layer may be set to any appropriate value as long as the difference in in-plane average refractive index with the second layer is 0.3 or less. When the first layer is a polarizer, the in-plane average refractive index of the first layer is, for example, 1.48 to 1.51. In this specification, the in-plane average refractive index is measured using a prism coupler SPA-4000 (manufactured by Cylon Technology) under conditions of a measurement temperature of 23°C and a measurement wavelength of 532 nm, and the direction in which the refractive index is maximum in the plane, and The refractive index is measured in a direction perpendicular to that direction, and is the average value of these values.

B-1. Polarizer A polarizer is typically composed of a polyvinyl alcohol (PVA) resin film containing a dichroic substance (for example, iodine). The thickness of the polarizer may be any suitable value as long as the thickness with the second layer is 6 μm or less. The thickness of the polarizer is preferably 1 μm to 8 μm, more preferably 1 μm to 7 μm, and even more preferably 2 μm to 5 μm. If the thickness of the polarizer is within this range, it can greatly contribute to making the optical laminate (for example, a polarizing plate) thinner.

The polarizer preferably exhibits absorption dichroism at a wavelength of 380 nm to 780 nm. The single transmittance Ts of the polarizer is preferably 40% to 48%, more preferably 41% to 46%. The degree of polarization P of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more. The above-mentioned single transmittance is typically a Y value measured using an ultraviolet-visible spectrophotometer and subjected to visibility correction. The degree of polarization is typically determined by the following formula based on parallel transmittance Tp and cross transmittance Tc measured using an ultraviolet-visible spectrophotometer and corrected for visibility.
Degree of polarization (%) = {(Tp-Tc)/(Tp+Tc)}1/2×100

Specific examples of polarizers obtained using the above-mentioned laminate of two or more layers include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material; Examples include polarizers obtained using a laminate of a base material and a PVA-based resin layer coated on the resin base material. A polarizer obtained using a laminate of a resin base material and a PVA-based resin layer coated on the resin base material can be obtained by, for example, applying a PVA-based resin solution to the resin base material and drying it. Forming a PVA-based resin layer thereon to obtain a laminate of a resin base material and the PVA-based resin layer; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer; obtain. In this embodiment, preferably, a polyvinyl alcohol resin layer containing a halide and a polyvinyl alcohol resin is formed on one side of the resin base material. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Furthermore, the stretching may further include stretching the laminate in air at a high temperature (for example, 95° C. or higher) before stretching in the boric acid aqueous solution, if necessary. In addition, in the present embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which the laminate is heated while being conveyed in the longitudinal direction to shrink by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an in-air auxiliary stretching process, a dyeing process, an underwater stretching process, and a drying shrinkage process in this order. By introducing auxiliary stretching, even when PVA is applied onto a thermoplastic resin, it becomes possible to improve the crystallinity of PVA and achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as deterioration of orientation and dissolution of PVA when it is immersed in water during the subsequent dyeing and stretching processes, resulting in high optical properties. becomes possible to achieve. Furthermore, when the PVA-based resin layer is immersed in a liquid, disturbance in the orientation of polyvinyl alcohol molecules and deterioration of orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. Thereby, the optical properties of a polarizer obtained through a treatment process performed by immersing the laminate in a liquid, such as dyeing treatment and underwater stretching treatment, can be improved. Furthermore, optical properties can be improved by shrinking the laminate in the width direction by drying shrinkage treatment. The obtained resin base material/polarizer laminate may be used as is (that is, the resin base material may be used as a protective layer for the polarizer), or the resin base material may be peeled from the resin base material/polarizer laminate. Any appropriate protective layer may be laminated on the peeled surface or on the surface opposite to the peeled surface depending on the purpose. Details of the method for manufacturing such a polarizer are described in, for example, Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire descriptions of these publications are incorporated herein by reference.

C. Second Layer The second layer is optically isotropic. In this specification, having optical isotropy means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is -10 nm to +10 nm. The in-plane retardation Re(550) is more preferably 0 nm to 5 nm, even more preferably 0 nm to 3 nm, and particularly preferably 0 nm to 2 nm. The retardation Rth (550) in the thickness direction is more preferably -5 nm to +5 nm, still more preferably -3 nm to +3 nm, particularly preferably -2 nm to +2 nm. Note that Re(550) is the in-plane retardation of the film measured with light having a wavelength of 550 nm at 23°C. Re(550) is determined by the formula: Re(550)=(nx-ny)×d. Rth (550) is the retardation in the thickness direction of the film measured with light having a wavelength of 550 nm at 23°C. Rth(550) is determined by the formula: Rth(550)=(nx−nz)×d. Here, nx is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., slow axis direction), and ny is the refractive index in the in-plane direction perpendicular to the slow axis (i.e., fast axis direction). It is a refractive index, nz is the refractive index in the thickness direction, and d is the thickness (nm) of the film.

The second layer contains a luminescent material having a molar extinction coefficient of 10000 L/mol·cm or more at a wavelength of 365 nm. Since the second layer contains a luminescent material, after measuring the luminescence amount of the second layer having an arbitrary thickness in advance, the thickness is accurately measured using, for example, SEM or TEM, and the thickness and luminescence amount of the second layer are measured. Thickness can be measured by creating a calibration curve that shows the relationship between Therefore, the thickness can be easily measured and a decrease in yield in the manufacturing process of the optical laminate can be suppressed.

The in-plane average refractive index of the second layer may be set to any appropriate value as long as the difference in in-plane average refractive index with the first layer is 0.3 or less. When the second layer is a resin layer, the in-plane average refractive index of the second layer is, for example, 1.49 to 1.51. The in-plane average refractive index can be measured by the method described above. When the in-plane refractive index is isotropic, the refractive index in any one direction within the plane (e.g. MD direction) and the direction perpendicular to that direction (e.g. TD direction) is measured, and these are averaged. refers to value.

The thickness of the second layer may be set to any appropriate thickness as long as the difference from the thickness of the first layer is 6 μm or less. In one embodiment, the thickness of the second layer is preferably less than 1 μm, more preferably between 0.1 μm and 0.9 μm, even more preferably between 0.3 μm and 0.7 μm. In one embodiment, the thickness of the second layer is within the above range, which can contribute to making the optical laminate thinner. Moreover, even if the thickness of the second layer is as thin as described above, the thickness can be easily measured.

In one embodiment, the second layer is a resin layer containing the above luminescent material. In one embodiment, the resin layer is preferably a solidified or thermoset product of a coating film of an organic solvent solution. Hereinafter, a case where the second layer is a solidified product or a thermoset product of a coating film of an organic solvent solution will be described in detail.

C-1. Luminescent material The second layer contains a luminescent material having a molar extinction coefficient of 10000 L/mol·cm or more at a wavelength of 365 nm. In this specification, a luminescent material refers to a substance that emits light of 420 nm to 480 nm when irradiated with light of 365 nm. The molar extinction coefficient of the luminescent material may be 10,000 L/mol·cm or more, and can be set to any appropriate value. The molar absorption number of the luminescent agent at a wavelength of 365 nm is, for example, 100,000 L/mol·cm or less, preferably 50,000 L/mol·cm or less.

As the luminescent material, any suitable substance having the above molar absorption number can be used. For example, triazole compounds, phthalimide compounds, virazolone compounds, stilbene compounds, oxazole compounds, naphthalimide compounds, rhodamine compounds, benzimidazole compounds, thiophene compounds, coumarin compounds, and derivatives thereof. can be mentioned. These may be used alone or in combination of two or more. Preferably, coumarin compounds and their derivatives are used because they have improved solubility and are stable as luminescent materials.

Coumarin derivatives are derivatives of organic compounds represented by the chemical formula (C ₉ H ₆ O ₂ ), and may have an organic group at any position of the aromatic ring and/or heterocycle. Examples of the organic group include an aliphatic hydrocarbon group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent. Examples of aliphatic hydrocarbon groups include linear or branched alkyl groups which may have a substituent having 1 to 20 carbon atoms or a hetero atom, and straight chain or branched alkyl groups which may have a substituent having 3 to 20 carbon atoms or a hetero atom. Examples include cyclic alkyl groups and alkenyl groups having 2 to 20 carbon atoms. Examples of the aryl group include a phenyl group which may have a substituent having 6 to 20 carbon atoms or a hetero atom, and a naphthyl group which may have a substituent having 10 to 20 carbon atoms or a hetero atom. . Examples of the heterocyclic group include a 5-membered or 6-membered ring group containing at least one heteroatom and optionally having a substituent. These may be connected to each other to form a ring. Preferably, a coumarin derivative having a diethylamino group as an organic group is used because it has a high molar absorption coefficient and has excellent luminescent properties even in a small amount.

Examples of coumarin derivatives include 7{[4-chloro-6-(diethylamino)-s-triazin-2-yl]amino}-7-triazinylamino-3-phenyl-coumarin, 8-amino-4- Methylcoumarin, 7-diethyldiamino-4-methylcoumarin, 3-cyano-7-hydrocoumarin, 7-hydroxycoumarin-3-carboxylic acid, 6,8-difluoro-7-hydroxy-4-methylcoumarin, 7-amino Examples include -4-methylcoumarin.

Note that when the second layer contains a polymerization initiator, some types of polymerization initiators emit fluorescence when irradiated with active energy rays. However, the intensity of the fluorescence emitted from the polymerization initiator (light emission amount) is quite low, so even if the composition (resin composition) forming the second layer contains a polymerization initiator, it is difficult to irradiate it with light. In this case, the amount of light emitted is almost not proportional to the thickness of the second layer. Furthermore, the fluorescence intensity emitted from the polymerization initiator changes depending on its chemical state, and since the polymerization initiator is decomposed and consumed as radicals are generated, the amount of light emitted may decrease over time. Therefore, the compound forming the second layer may contain a polymerization initiator. From these points, it is preferable to use a stable (non-consumable) luminescent material as the luminescent material, and particularly stable coumarin-based compounds and derivatives thereof are preferred. Preferably, a polymerization initiator and the above-mentioned preferred luminescent material can be used in combination.

In the composition (resin composition) forming the second layer, the luminescent material can be used in any appropriate amount. The content of the luminescent material is preferably 0.1 part by weight to 1 part by weight, more preferably 0.1 part by weight to 0.5 part by weight, based on 100 parts by weight of the resin contained in the resin composition. . If the content of the luminescent material is too small, it may not be possible to obtain the amount of luminescence necessary for detecting the thickness of the second layer. If the content of the luminescent material is too large, insoluble portions of the luminescent material may be generated in the composition forming the second layer, or optical properties, adhesive properties, etc. may be adversely affected.

C-2. Resin In one embodiment, the second layer is a resin layer. In this embodiment, the second layer is formed using a composition including, for example, any suitable resin and luminescent material. Any suitable resin can be used as the resin (base polymer) constituting the resin layer. Only one type of resin may be used, or two or more types may be used in combination.

In one embodiment, preferably a resin having a glass transition temperature (Tg) of, for example, 85° C. or higher and a weight average molecular weight Mw of, for example, 25,000 or higher is used. If the Tg and Mw of the resin are within such ranges, the second layer may be formed of a solidified or thermoset coating film of an organic solvent solution of the resin, for example, the first layer may be a polarizer. Despite its extremely thin thickness, it can achieve excellent durability under high temperature and high humidity environments. The Tg of the resin is preferably 90°C or higher, more preferably 100°C or higher, even more preferably 110°C or higher, particularly preferably 120°C or higher. Tg can be, for example, 200°C or less. Further, the Mw of the resin is preferably 30,000 or more, more preferably 35,000 or more, and even more preferably 40,000 or more. Mw can be, for example, 150,000 or less.

As the resin, any suitable thermoplastic resin or thermosetting resin may be used as long as it can form a solidified or thermoset film of the organic solvent solution and has the above Tg and Mw. Can be used. Preferably it is a thermoplastic resin. Examples of thermoplastic resins include acrylic resins and epoxy resins. You may use a combination of an acrylic resin and an epoxy resin.

Acrylic resins typically contain repeating units derived from (meth)acrylic acid ester monomers having a linear or branched structure as a main component. In this specification, (meth)acrylic refers to acrylic and/or methacrylic. The acrylic resin may contain repeating units derived from any suitable comonomer depending on the purpose. Examples of the comonomer (comonomer) include carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, and heterocycle-containing vinyl monomers. By appropriately setting the type, number, combination, copolymerization ratio, etc. of monomer units, an acrylic resin having the above-mentioned predetermined Mw can be obtained.

（式中、Ｘはビニル基、（メタ）アクリル基、スチリル基、（メタ）アクリルアミド基、ビニルエーテル基、エポキシ基、オキセタン基、ヒドロキシル基、アミノ基、アルデヒド基、および、カルボキシル基からなる群より選択される少なくとも１種の反応性基を含む官能基を表し、Ｒ^１およびＲ^２はそれぞれ独立して、水素原子、置換基を有していてもよい脂肪族炭化水素基、置換基を有していてもよいアリール基、または、置換基を有していてもよいヘテロ環基を表し、Ｒ^１およびＲ^２は互いに連結して環を形成してもよい）。 <Boron-containing acrylic resin>
In one embodiment, the acrylic resin contains more than 50 parts by weight of a (meth)acrylic monomer and more than 0 parts by weight and less than 50 parts by weight of a monomer represented by formula (1) (hereinafter referred to as , a copolymer obtained by polymerizing a monomer mixture containing (sometimes referred to as a comonomer) (hereinafter sometimes referred to as a boron-containing acrylic resin):

(wherein, Represents a functional group containing at least one selected reactive group, and R ¹ and R ² each independently represent a hydrogen atom, an aliphatic hydrocarbon group that may have a substituent, or a functional group containing a substituent. represents an aryl group which may have a substituent or a heterocyclic group which may have a substituent, and R ¹ and R ² may be connected to each other to form a ring).

（式中、Ｒ^６は任意の官能基を表し、jおよびｋは１以上の整数を表す）。 The boron-containing acrylic resin typically has a repeating unit represented by the following formula. By polymerizing a monomer mixture containing a comonomer represented by formula (1) and a (meth)acrylic monomer, the boron-containing acrylic resin has a substituent containing boron in the side chain (for example, It has a repeating unit of k in the following formula. Thereby, in an optical laminate that uses a polarizer as the first layer, when the resin layer is disposed adjacent to the polarizer, the adhesion to the polarizer can be improved. This boron-containing substituent may be contained continuously (that is, in a block form) in the boron-containing acrylic resin, or may be contained randomly.

(In the formula, R ⁶ represents an arbitrary functional group, and j and k represent an integer of 1 or more).

<(meth)acrylic monomer>
Any suitable (meth)acrylic monomer can be used as the (meth)acrylic monomer. Examples include (meth)acrylic acid ester monomers having a linear or branched structure, and (meth)acrylic acid ester monomers having a cyclic structure.

Examples of (meth)acrylic acid ester monomers having a linear or branched structure include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and (meth)acrylic acid. Examples include isopropyl, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, methyl 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, etc. . Preferably, methyl (meth)acrylate is used. The (meth)acrylic acid ester monomers may be used alone or in combination of two or more.

Examples of (meth)acrylic acid ester monomers having a cyclic structure include cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, ( Dicyclopentenyl meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, biphenyl (meth)acrylate, o-biphenyloxyethyl (meth)acrylate, o-biphenyloxyethoxy Ethyl (meth)acrylate, m-biphenyloxyethyl acrylate, p-biphenyloxyethyl (meth)acrylate, o-biphenyloxy-2-hydroxypropyl (meth)acrylate, p-biphenyloxy-2-hydroxypropyl (meth)acrylate , m-biphenyloxy-2-hydroxypropyl (meth)acrylate, N-(meth)acryloyloxyethyl-o-biphenyl carbamate, N-(meth)acryloyloxyethyl-p-biphenyl carbamate, N-(meth) Examples include biphenyl group-containing monomers such as acryloyloxyethyl-m-biphenyl carbamate and o-phenylphenol glycidyl ether acrylate, terphenyl (meth)acrylate, and o-terphenyloxyethyl (meth)acrylate. Preferably, 1-adamantyl (meth)acrylate and dicyclopentanyl (meth)acrylate are used. By using these monomers, a polymer with a high glass transition temperature can be obtained. These monomers may be used alone or in combination of two or more.

A silsesquioxane compound having a (meth)acryloyl group may be used instead of the above-mentioned (meth)acrylic acid ester monomer. By using a silsesquioxane compound, an acrylic polymer with a high glass transition temperature can be obtained. Silsesquioxane compounds are known to have various skeleton structures, such as cage-shaped structures, ladder-shaped structures, and random structures. The silsesquioxane compound may have only one type of these structures, or may have two or more types of these structures. Only one type of silsesquioxane compound may be used, or two or more types may be used in combination.

As the silsesquioxane compound containing a (meth)acryloyl group, for example, MAC grade and AC grade manufactured by Toagosei Co., Ltd. SQ series can be used. MAC grade is a silsesquioxane compound containing a methacryloyl group, and specific examples thereof include MAC-SQ TM-100, MAC-SQ SI-20, MAC-SQ HDM, and the like. AC grade is a silsesquioxane compound containing an acryloyl group, and specific examples thereof include AC-SQ TA-100 and AC-SQ SI-20.

The (meth)acrylic monomer is used in an amount exceeding 50 parts by weight based on 100 parts by weight of the monomer mixture.

<Comonomer>
As the copolymerizable monomer, a monomer represented by the above formula (1) is used. By using such a comonomer, a boron-containing substituent is introduced into the side chain of the resulting polymer. Only one type of copolymerizable monomer may be used, or two or more types may be used in combination.

The aliphatic hydrocarbon group in the above formula (1) includes a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, and a straight chain or branched alkyl group having 3 to 20 carbon atoms which may have a substituent. Examples include a cyclic alkyl group having 20 carbon atoms and an alkenyl group having 2 to 20 carbon atoms. Examples of the aryl group include a phenyl group having 6 to 20 carbon atoms which may have a substituent, and a naphthyl group having 10 to 20 carbon atoms which may have a substituent. Examples of the heterocyclic group include a 5-membered cyclic group or a 6-membered cyclic group containing at least one heteroatom which may have a substituent. Note that R ¹ and R ² may be connected to each other to form a ring. R ¹ and R ² are preferably a hydrogen atom or a linear or branched alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom.

The reactive groups contained in the functional group represented by and at least one selected from the group consisting of carboxyl groups. Preferably, the reactive groups are (meth)acrylic and/or (meth)acrylamide groups. By having these reactive groups, in an optical laminate using a polarizer as the first layer, when the resin layer is disposed adjacent to the polarizer, the adhesion with the polarizer can be further improved.

In one embodiment, the functional group represented by X is preferably a functional group represented by ZY-. Here, Z is selected from the group consisting of vinyl group, (meth)acrylic group, styryl group, (meth)acrylamide group, vinyl ether group, epoxy group, oxetane group, hydroxyl group, amino group, aldehyde group, and carboxyl group. Y represents a phenylene group or an alkylene group.

Specifically, the following compounds can be used as the copolymerizable monomer.

The copolymerizable monomer is used in a content of more than 0 parts by weight and less than 50 parts by weight based on 100 parts by weight of the monomer mixture. The amount is preferably 0.01 parts by weight or more and less than 50 parts by weight, more preferably 0.05 parts by weight to 20 parts by weight, even more preferably 0.1 parts by weight to 10 parts by weight, and particularly preferably 0.05 parts by weight to 20 parts by weight. The amount is 5 parts by weight to 5 parts by weight.

<Acrylic resin containing lactone rings, etc.>

In another embodiment, the acrylic resin has repeating units that include a ring structure selected from lactone ring units, glutaric anhydride units, glutarimide units, maleic anhydride units, and maleimide (N-substituted maleimide) units. . Only one type of repeating unit containing a ring structure may be included in the repeating unit of the acrylic resin, or two or more types may be included.

The lactone ring unit is preferably represented by the following general formula (2):

一般式（２）において、Ｒ^２、Ｒ^３およびＲ^４は、それぞれ独立して、水素原子または炭素数１～２０の有機残基を表す。なお、有機残基は酸素原子を含んでいてもよい。アクリル系樹脂には、単一のラクトン環単位のみが含まれていてもよく、上記一般式（２）におけるＲ^２、Ｒ^３およびＲ^４が異なる複数のラクトン環単位が含まれていてもよい。ラクトン環単位を有するアクリル系樹脂は、例えば特開２００８－１８１０７８号公報に記載されており、当該公報の記載は本明細書に参考として援用される。

In general formula (2), R ² , R ³ and R ⁴ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. Note that the organic residue may contain an oxygen atom. The acrylic resin may contain only a single lactone ring unit, or may contain multiple lactone ring units in which R ² , R ³ and R ⁴ in the above general formula (2) are different. . Acrylic resins having lactone ring units are described, for example, in JP-A No. 2008-181078, and the description in this publication is incorporated herein by reference.

The glutarimide unit is preferably represented by the following general formula (3):

In the general formula (3), R ¹¹ and R ¹² each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ¹³ represents an alkyl group having 1 to 18 carbon atoms, or an alkyl group having 3 to 12 carbon atoms. represents a cycloalkyl group or an aryl group having 6 to 10 carbon atoms. In general formula (3), preferably R ¹¹ and R ¹² are each independently hydrogen or a methyl group, and R ¹³ is hydrogen, a methyl group, a butyl group, or a cyclohexyl group. More preferably, R ¹¹ is a methyl group, R ¹² is hydrogen, and R ¹³ is a methyl group. The acrylic resin may contain only a single glutarimide unit, or may contain multiple glutarimide units in which R ¹¹ , R ¹² and R ¹³ in the above general formula (3) are different. . Acrylic resins having glutarimide units are disclosed in, for example, JP-A Nos. 2006-309033, 2006-317560, 2006-328334, 2006-337491, and 2006-337492. It is described in Japanese Patent Application Laid-open Nos. 2006-337493 and 2006-337569, and the descriptions of these publications are incorporated herein by reference. Regarding the glutaric anhydride unit, the above explanation regarding the glutarimide unit applies, except that the nitrogen atom substituted with R ¹³ in the above general formula (3) becomes an oxygen atom.

As for the maleic anhydride unit and the maleimide (N-substituted maleimide) unit, the structures are specified from the names, so specific explanations will be omitted.

The content of repeating units containing a ring structure in the acrylic resin is preferably 1 mol% to 50 mol%, more preferably 10 mol% to 40 mol%, even more preferably 20 mol% to 30 mol%. Note that the acrylic resin includes a repeating unit derived from the above-mentioned (meth)acrylic monomer as a main repeating unit.

<Epoxy resin>
As the epoxy resin, preferably an epoxy resin having an aromatic ring is used. By using an epoxy resin having an aromatic ring as the epoxy resin, the adhesion between the resin layer and the polarizer can be improved in an optical laminate that uses a polarizer as the first layer. Furthermore, when the adhesive layer is disposed adjacent to the resin layer, the anchoring power of the adhesive layer can be improved. Examples of epoxy resins having an aromatic ring include bisphenol epoxy resins such as bisphenol A epoxy resin, bisphenol F epoxy resin, and bisphenol S epoxy resin; phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolak. Novolac-type epoxy resins such as epoxy resins; polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone, epoxidized polyvinylphenol, naphthol-type epoxy resins, naphthalene-type epoxy resins, biphenyl-type epoxy resins Examples include epoxy resin. Preferably, bisphenol A type epoxy resin, biphenyl type epoxy resin, and bisphenol F type epoxy resin are used. Only one type of epoxy resin may be used, or two or more types may be used in combination.

The second layer, which is a resin layer, can be formed by applying an organic solvent solution of the resin as described above to form a coating film, and solidifying or thermosetting the coating film. As the organic solvent, any suitable organic solvent that can dissolve or uniformly disperse the acrylic resin can be used. Specific examples of organic solvents include ethyl acetate, toluene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone. The resin concentration of the solution is preferably 3 to 20 parts by weight based on 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film can be formed.

The solution may be applied to any suitable substrate and may be applied to a polarizer. When applying a solution to a base material, a solidified product (resin layer) of the coating film formed on the base material is transferred to a polarizer. When applying a solution to a polarizer, a protective layer is directly formed on the polarizer by drying (solidifying) the coating film. Preferably, the solution is applied to a polarizer to form a protective layer directly on the polarizer. With such a configuration, the adhesive layer or pressure-sensitive adhesive layer required for transfer can be omitted, so the polarizing plate can be made even thinner. Any suitable method can be adopted as a method for applying the solution. Specific examples include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and knife coating (comma coating, etc.).

A resin layer can be formed by solidifying or thermally curing a coating film of a solution. The heating temperature for solidification or thermosetting is preferably 100°C or lower, more preferably 50°C to 70°C. If the heating temperature is within this range, adverse effects on the polarizer can be prevented. Heating time can vary depending on the heating temperature. The heating time can be, for example, 1 minute to 10 minutes.

The resin layer (substantially an organic solvent solution of the resin) may contain any suitable additive depending on the purpose. Specific examples of additives include ultraviolet absorbers; leveling agents; antioxidants such as hindered phenol, phosphorus, and sulfur; stabilizers such as light stabilizers, weather stabilizers, and heat stabilizers; glass fibers; Reinforcing materials such as carbon fibers; near-infrared absorbers; flame retardants such as tris(dibromopropyl) phosphate, triallyl phosphate, and antimony oxide; antistatic agents such as anionic, cationic, and nonionic surfactants; inorganic pigments , colorants such as organic pigments and dyes; organic fillers or inorganic fillers; resin modifiers; organic fillers and inorganic fillers; plasticizers; lubricants; antistatic agents; flame retardants; and the like. The type, number, combination, amount, etc. of additives can be appropriately set depending on the purpose.

D. Method for manufacturing optical laminate The optical laminate can be manufactured by any suitable method. For example, it can be manufactured by laminating the second layer on the first layer via any suitable adhesive layer (adhesive layer or pressure-sensitive adhesive layer). In one embodiment, the optical laminate is formed by applying a composition (organic solvent solution) for forming the second layer to the first layer, and solidifying or thermosetting the coating film. In the case of an optical laminate in which the first layer is a polarizer and the second layer is a resin layer containing the boron-containing acrylic polymer, by producing the optical laminate using such a manufacturing method. , a second layer is adjacent to the first layer. This can improve the adhesion between the first layer and the second layer.

EXAMPLES Hereinafter, embodiments of the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The method for measuring each characteristic is as follows. Note that unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on weight.

(1) Thickness The thickness of each layer was measured using a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

(2) Molar absorption number The luminescent material used in the example or comparative example was dissolved in a solvent (methanol), and the absorbance at a wavelength of 365 nm was measured using a UV-Vis-NIR spectrometer (Cary 5000, manufactured by Agilent Technologies). . The molar absorption number was calculated from the obtained absorbance using the following formula.
A=εLc
(A is the absorbance, ε is the molar extinction coefficient (mol ⁻¹・L・cm ⁻¹ ), c is the concentration of the measured substance in the solution (mol/L), and L is the optical path length (cm))

(3) In-plane average refractive index The in-plane average refractive index was measured using a prism coupler SPA-4000 (manufactured by Cylon Technology). Regarding the first layer, which is a polarizer, the in-plane refractive index was measured in the transmission axis direction and the absorption axis direction, respectively, and the average value of these values was taken as the in-plane average refractive index. Regarding the second layer, the in-plane refractive index was measured in the MD direction and the TD direction, and the average value of these values was taken as the in-plane average refractive index.

[Example 1-1 and 1-2]
1. Preparation of the first layer (polarizer) As a thermoplastic resin base material, a long, amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a water absorption rate of 0.75% and a Tg of approximately 75°C is used. ) was used. One side of the resin base material was subjected to corona treatment.
100 weight PVA resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., trade name "Gosefaimer Z410") at a ratio of 9:1. 13 parts by weight of potassium iodide was added to 13 parts by weight of potassium iodide and dissolved in water to prepare a PVA aqueous solution (coating liquid).
The PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60° C. to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate.
The obtained laminate was uniaxially stretched free end to 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds in an oven at 130° C. (in-air auxiliary stretching treatment).
Next, the laminate was immersed for 30 seconds in an insolubilization bath (boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. (insolubilization treatment).
Next, the final polarizer was added to a dyeing bath (an aqueous iodine solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 to 100 parts by weight of water) at a liquid temperature of 30°C. The sample was immersed for 60 seconds while adjusting the concentration so that the single transmittance (Ts) was 43.0% or more (staining treatment).
Next, it was immersed for 30 seconds in a crosslinking bath (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C. (Crosslinking treatment).
Thereafter, while immersing the laminate in a boric acid aqueous solution (boric acid concentration: 4.0% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70°C, the laminate was moved in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds. Uniaxial stretching was performed so that the total stretching ratio was 5.5 times (underwater stretching treatment).
Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (cleaning treatment).
Thereafter, while drying in an oven maintained at 90°C, it was brought into contact with a SUS heating roll whose surface temperature was maintained at 75°C for about 2 seconds (drying shrinkage treatment). The shrinkage rate of the laminate in the width direction due to the drying shrinkage treatment was 5.2%.
In this way, a polarizer (first layer) with a thickness of 5 μm was formed on the resin base material.

2. Preparation of polarizing plate A triacetyl cellulose (TAC) film (thickness 25 μm) was applied as a protective layer to the surface of the polarizer obtained above (the surface opposite to the resin base material) via an ultraviolet curable adhesive. Pasted together. Specifically, the curable adhesive was applied to have a total thickness of 1.0 μm, and then bonded together using a roll machine. Thereafter, the adhesive was cured by irradiating UV light from the protective layer side. Next, the resin base material was peeled off to obtain a polarizing plate having a structure of protective layer (TAC film)/adhesive layer/polarizer.

3. Preparation of optical laminate 97.0 parts of methyl methacrylate (MMA, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., trade name "Methyl methacrylate monomer"), 3. comonomer represented by the above general formula (1e). 0 parts and 0.2 parts of a polymerization initiator (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., trade name "2,2'-azobis(isobutyronitrile)") were dissolved in 200 parts of toluene. Next, a polymerization reaction was carried out for 5.5 hours while heating at 70° C. in a nitrogen atmosphere to obtain a boron-containing acrylic resin solution (solid content concentration: 33%). The obtained boron-containing acrylic polymer had a Tg of 110°C and a Mw of 80,000. 20 parts of the obtained boron-containing acrylic resin was dissolved in 80 parts of methyl ethyl ketone to obtain a resin solution (20%). To this resin solution, 0.5 parts by weight of 8-amino-4-methylcoumarin (manufactured by Showa Kagaku Kogyo Co., Ltd., trade name: HakkolP) as a luminescent material was added and mixed with respect to 100 parts by weight of the boron-containing acrylic resin. Next, the polarizer surface of the laminate is coated using a wire bar, and the coated film is dried at 60° C. for 5 minutes to form a second layer composed of a solidified coated film of an organic solvent solution of the resin. An optical laminate was obtained. Note that optical laminates were produced with the coating thickness of the resin layer being 0.4 μm (Example 1-1) or 0.8 μm (Example 1-2).

[Example 2-1 and 2-2]
Instead of 8-amino-4-methylcoumarin as a luminescent material, 7{[4-chloro-6-(diethylamino)-s-triazin-2-yl]amino}-7-triazinylamino-3-phenyl- An optical laminate was produced in the same manner as in Example 1 except that coumarin (manufactured by Showa Kagaku Kogyo Co., Ltd., trade name: Hakkol PY1800) was used.

(Comparative Examples 1-1 and 1-2)
2-Benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (manufactured by BASF, trade name: IRGACURE 369) was used as a luminescent material instead of 8-amino-4-methylcoumarin. An optical laminate was produced in the same manner as in Example 1 except for this.

[evaluation]
In each Example and Comparative Example, the amount of light emitted was measured for an optical laminate in which the second layer had a thickness of 0.4 μm and an optical laminate in which the second layer had a thickness of 0.8 μm.
Specifically, the second layer (resin layer) is irradiated with light having a wavelength of 365 nm in the vertical direction, and the amount of light emitted (fluorescence amount) of light with a wavelength of 420 nm to 480 nm is measured using a fluorescence amount measuring device (manufactured by Sentech Co., Ltd.). The measurement was carried out using a model number: OL201). If the difference between the luminescence amount of the 0.4 μm optical laminate and the 0.8 μm optical laminate is 5 or more, a calibration curve can be created (○), and if it is less than 5, a calibration curve cannot be created ( x).

In the optical laminates obtained in Examples 1 and 2, the amount of luminescence varied greatly depending on the change in thickness, and it was possible to create a calibration curve. Therefore, the film thickness could be easily measured by using the calibration curve. On the other hand, in the comparative example, the change in luminescence amount was small, making it difficult to create a calibration curve.

Embodiments of the present invention can suppress variations in optical properties and provide an optical laminate that can be manufactured with high yield. The optical laminate of the embodiment of the present invention can be widely used in liquid crystal panels such as liquid crystal televisions, liquid crystal displays, mobile phones, digital cameras, video cameras, portable game consoles, car navigation systems, copy machines, printers, fax machines, watches, and microwave ovens. can be applied.

10 First layer 20 Second layer 100 Optical laminate

Claims (4)

comprising a first layer having refractive index anisotropy and a second layer being optically isotropic,
The first layer is a polarizer, and the second layer contains more than 50 parts by weight of an acrylic monomer and more than 0 parts by weight and less than 50 parts by weight of a compound represented by formula (1). A solidified layer of a coating film of an organic solvent solution containing a polymer obtained by polymerizing with a polymer monomer,
The second layer contains a luminescent material whose molar absorption coefficient at a wavelength of 365 nm is 10,000 L/mol cm or more,
The difference between the in-plane average refractive index at a wavelength of 550 nm of the first layer and the in-plane average refractive index at a wavelength of 550 nm of the second layer is 0.05 or less,
The difference between the thickness of the first layer and the thickness of the second layer is 6 μm or less,
Optical laminate :

(wherein, Represents a functional group containing at least one selected reactive group, and R ¹ and R ² each independently represent a hydrogen atom, an aliphatic hydrocarbon group that may have a substituent, or a functional group containing a substituent. represents an aryl group which may have a substituent or a heterocyclic group which may have a substituent, and R ¹ and R ² may be connected to each other to form a ring). The optical laminate according to claim 1 , wherein the second layer has a thickness of less than 1 μm. The optical laminate according to claim 1 or 2 , wherein the luminescent material is at least one selected from coumarin compounds and derivatives thereof. The optical laminate according to any one of claims 1 to 3 , wherein the organic solvent solution contains 0.1 to 0.5 parts by weight of the luminescent material based on 100 parts by weight of the resin.

Images