KR20230152586A - Laminate and image display device using the same - Google Patents

Abstract

The object of the present invention is to provide a laminate that is thin and has excellent adhesion between members.
A laminate according to an embodiment of the present invention includes a polarizing plate including a polarizer, a functional layer, a resin layer and an adhesive layer disposed between the polarizing plate and the functional layer, and the resin layer and the adhesive layer are It is disposed adjacently, and the resin layer includes a resin having a glass transition temperature of 85° C. or higher and a weight average molecular weight Mw of 50,000 to 500,000, and an isocyanate compound, wherein the isocyanate compound is tolylene diisocyanate, diphenylmethane diisocyanate, , xylylene diisocyanate, and their derivatives, and the content of the resin in the resin layer is 50% by weight or more and 90% by weight or less, and the content of the isocyanate compound in the resin layer is 10% by weight. % by weight or more and 50% by weight or less, the adhesive layer is composed of a cured layer of the adhesive composition, and the octanol/water partition coefficient logPow calculated by the weighted average of the mole fractions of the monomer components contained in the adhesive composition is 1.5. It is less than or equal to 4.0.

Description

Laminate and image display device using the same {LAMINATE AND IMAGE DISPLAY DEVICE USING THE SAME}

The present invention relates to a laminate and an image display device using the same.

In recent years, image display devices represented by liquid crystal displays and electroluminescence (EL) display devices (e.g., organic EL display devices and inorganic EL display devices) are rapidly becoming popular. A polarizing plate is generally used in an image display panel mounted on an image display device. Typically, a laminate in which functional layers such as a polarizing plate and a retardation layer are integrated is widely used (for example, patent document 1). Recently, there is a stronger demand for thinner image display devices, and there is also a strong demand for thinner laminates.

Japanese Patent Publication No. 3325560

As the thickness of the laminate increases, there are cases where sufficient adhesion between members constituting the laminate cannot be secured.

The present invention was made in view of the above, and its main purpose is to provide a thin laminate with excellent adhesion between members.

1. A laminate according to an embodiment of the present invention includes a polarizing plate including a polarizer, a functional layer, a resin layer and an adhesive layer disposed between the polarizing plate and the functional layer, and the resin layer and the adhesive The layers are arranged adjacently, and the resin layer includes a resin having a glass transition temperature of 85° C. or higher and a weight average molecular weight Mw of 50,000 to 500,000, and an isocyanate compound, wherein the isocyanate compound is tolylene diisocyanate, diphenylmethane, Contains at least one selected from diisocyanate, xylylene diisocyanate, and their derivatives, the content of the resin in the resin layer is 50% by weight or more and 90% by weight or less, and the content of the isocyanate compound in the resin layer is 10% by weight or more and 50% by weight or less, and the adhesive layer is composed of a cured layer of the adhesive composition, and the octanol/water partition coefficient logPow calculated by the weighted average of the mole fractions of the monomer components contained in the adhesive composition. is 1.5 or more and 4.0 or less.

2. In the laminate described in 1 above, the content of the monomer component having an octanol/water partition coefficient logPow of 0.0 or less may be 30 parts by weight or less with respect to 100 parts by weight of the monomer component contained in the adhesive composition.

3. In the laminate according to item 1 or 2, the resin layer may further contain at least one of hexamethylene diisocyanate or a derivative thereof as the isocyanate compound.

4. In the laminate according to any one of 1 to 3 above, the thickness of the adhesive layer may be 3 μm or less.

5. In the laminate according to any one of 1 to 4 above, the thickness of the resin layer may be 1 μm or less.

6. In the laminate according to any one of 1 to 5 above, the resin layer may be disposed adjacent to the polarizer.

7. In the laminate according to any one of 1 to 6 above, the functional layer may be a retardation layer.

8. An image display device according to an embodiment of the present invention includes the laminate according to any one of 1 to 7 above.

9. The method for manufacturing a laminate according to an embodiment of the present invention includes forming a resin layer by applying an organic solvent solution containing a resin and an isocyanate compound to a polarizing plate or functional layer containing a polarizer, and the resin layer. and bonding the functional layer or the polarizing plate through an adhesive composition, wherein the resin has a glass transition temperature of 85° C. or higher and a weight average molecular weight Mw of 50,000 to 500,000, and the isocyanate compound is tolylenedi. It contains at least one selected from isocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and derivatives thereof, and the content of the resin in the resin layer is 50% by weight or more and 90% by weight or less, and The content of the isocyanate compound is 10% by weight or more and 50% by weight or less, and the octanol/water partition coefficient logPow calculated by the weighted average of the mole fractions of the monomer components contained in the adhesive composition is 1.5 or more and 4.0 or less.

According to an embodiment of the present invention, a thin laminate with excellent adhesion between members can be obtained.

1 is a schematic cross-sectional view showing the schematic structure of a laminate according to one embodiment of the present invention.
Fig. 2 is a schematic cross-sectional view showing the schematic configuration of an image display panel according to one embodiment of the present invention.
Figure 3 is a cross-sectional SEM observation photo of Example 1.
Figure 4 is a cross-sectional SEM observation photo of Comparative Example 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In addition, in order to make the explanation clearer, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the embodiment, but are only examples and do not limit the interpretation of the present invention.

(Definition of terms and symbols)

The definitions of terms and symbols in this specification are as follows.

(1) Refractive index (nx, ny, nz)

'nx' is the refractive index in the direction where the in-plane refractive index is maximum (i.e., slow axis direction), 'ny' is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., fast axis direction), and 'nz' is It is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

'Re(λ)' is the in-plane phase difference measured with light with a wavelength of λnm at 23°C. For example, 'Re(550)' is the in-plane retardation measured with light with a wavelength of 550 nm at 23°C. Re(λ) can be obtained by the formula: Re(λ)=(nx-ny)×d, when the thickness of the layer (film) is d(nm).

(3) Phase difference in the thickness direction (Rth)

'Rth(λ)' is the phase difference in the thickness direction measured with light with a wavelength of λnm at 23°C. For example, 'Rth(550)' is the phase difference in the thickness direction measured with light with a wavelength of 550 nm at 23°C. Rth(λ) can be obtained by the formula: Rth(λ)=(nx-nz)×d when the thickness of the layer (film) is d(nm).

(4) Nz coefficient

The Nz coefficient can be obtained by Nz=Rth/Re.

(5) angle

When an angle is mentioned herein, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Therefore, for example, '45°' means ±45°.

A. Laminate

1 is a schematic cross-sectional view showing the schematic configuration of a laminate according to one embodiment of the present invention. The laminate 100 includes a polarizing plate 10, a resin layer 20, an adhesive layer 30, and a functional layer 40 in this order from the top in FIG. 1 .

The polarizing plate 10 includes a polarizer 11 including a first main surface 11a and a second main surface 11b facing each other, and a protective layer disposed on the first main surface 11a of the polarizer 11. (12) is further included. In the illustrated example, no protective layer is disposed between the polarizer 11 and the resin layer 20, and the resin layer 20 is disposed adjacent to the polarizer 11. Omitting the protective layer can contribute to thinning the laminate. The laminate 100 is typically arranged so that the polarizer 11 is on the viewing side rather than the resin layer 20 in an image display device.

In the illustrated example, the polarizing plate 10 includes a polarizer 11 and a protective layer 12 disposed on the first main surface 11a side of the polarizer 11, but additionally includes a polarizer 11 on the second main surface 11 of the polarizer 11. A second protective layer disposed on the (11b) side may be included. Additionally, the polarizing plate 10 includes a polarizer 11 and a protective layer 12, but the protective layer 12 may be omitted.

In the illustrated example, the polarizing plate 10, the resin layer 20, the adhesive layer 30, and the functional layer 40 are arranged in this order, but unlike the illustrated example, the adhesive layer 30 is connected to the polarizing plate 10. It is arranged on the side, and the resin layer 20 may be arranged on the functional layer 40 side.

The resin layer 20 and the adhesive layer 30 are disposed adjacent to each other. It is desirable that an interface is confirmed between the resin layer 20 and the adhesive layer 30. Alternatively, it is preferable that an intermediate layer containing components derived from the resin layer 20 and components derived from the adhesive layer is not formed between the resin layer 20 and the adhesive layer 30. The intermediate layer may be formed, for example, by melting (compatibilizing) a part of the resin layer into the adhesive composition forming the adhesive layer when forming the adhesive layer. By adopting a state in which an interface is formed (no intermediate layer is formed), excellent adhesion to the resin layer can be obtained without impairing the function of the resin layer. Confirmation of the interface or intermediate layer can be performed, for example, by observation with a scanning electron microscope (SEM).

The functional layer 40 can be made of any suitable optical member. Typically, the functional layer 40 may function as a phase difference layer. In this case, the laminate 100 may be referred to as a polarizing plate with a retardation layer. By using an adhesive layer for lamination of a resin layer and a functional layer or a polarizing plate, the thickness of the adhesive layer between the resin layer and the functional layer or the polarizing plate can be made very thin (e.g., less than 5 μm), allowing for thinning of the laminate. can make a big contribution. Additionally, the resulting laminate may also have excellent bending properties.

Although not shown, the laminated body (polarizing plate with retardation layer) may further include other functional layers. The type, characteristics, number, combination, arrangement, etc. of other functional layers that the laminate may include can be appropriately set depending on the purpose. For example, the resin layer 20 can reduce the influence that the polarizer 11 may have on other members, but the laminate may further include such a resin layer. Additionally, for example, the polarizing plate with a retardation layer may further include a conductive layer or an isotropic base material with a conductive layer. A polarizing plate with a retardation layer containing a conductive layer or an isotropic substrate with a conductive layer is applied, for example, to a so-called inner touch panel type input display device in which a touch sensor is built into the image display panel. As another example, the polarizing plate with a retardation layer may further include another retardation layer. The optical properties (e.g., refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement, etc. of the other retardation layers can be appropriately set depending on the purpose. As a specific example, on the viewer's side of the polarizer, another phase difference layer (typically a layer that provides a (other) circular polarization function and a layer that provides an ultra-high phase difference) that improves visibility when viewed through polarized sunglasses is provided. do. By including such a layer, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses, and can also be suitably applied to an image display device that can be used outdoors.

Each member constituting the laminate may be laminated with any suitable adhesive layer interposed therebetween. Specific examples of the adhesive layer include an adhesive layer and an adhesive layer. For example, the protective layer 12 is bonded to the polarizer 11 through an adhesive layer (preferably using an active energy ray-curable adhesive). The thickness of the adhesive layer is, for example, 0.05 μm or more, preferably 0.4 μm to 3.0 μm, and more preferably 0.6 μm to 2.2 μm.

Although not shown, an adhesive layer may be provided on the side of the functional layer 40 where the polarizing plate 10 is not disposed, and by this adhesive layer, for example, the laminate 100 can display images included in an image display device. It can be attached to a panel. The thickness of the adhesive layer is preferably 10 μm to 20 μm.

The laminate may be sheet-shaped or elongated. In this specification, 'elongated shape' means an elongated shape with a sufficiently long length relative to the width, and includes, for example, an elongated shape whose length is 10 or more times the width, preferably 20 times or more. A long-length laminate can be wound into a roll.

B. Polarizer

The polarizing plate includes a polarizer including a first main surface and a second main surface opposing each other, and further includes a protective layer disposed on the first main surface side and/or a second protective layer disposed on the second main surface side. do.

B-1. polarizer

The polarizer is typically made of a polyvinyl alcohol (PVA)-based resin film containing a dichroic substance. The thickness of the polarizer is preferably 1 μm to 8 μm, more preferably 1 μm to 7 μm, and still more preferably 2 μm to 5 μm. Such a thickness can, for example, greatly contribute to reducing the thickness of the laminated body.

The boric acid content of the polarizer is preferably 10% by weight or more, and more preferably 13% by weight to 25% by weight. If the boric acid content of the polarizer is within this range, the ease of curl adjustment during bonding is maintained satisfactorily due to a synergistic effect with the iodine content described later, and curling during heating is well suppressed, while heating. Appearance durability can be improved. The boric acid content can be calculated as the amount of boric acid contained in the polarizer per unit weight using the following formula from a neutralization method, for example.

The iodine content of the polarizer is preferably 2% by weight or more, and more preferably 2% by weight to 10% by weight. If the iodine content of the polarizer is in this range, the synergistic effect with the boric acid content described above maintains the ease of curl adjustment during bonding, and further suppresses curl during heating, while Appearance durability can be improved. In this specification, 'iodine content' means the amount of all iodine contained in the polarizer (PVA-based resin film). More specifically, among polarizers, iodine exists in the form of iodine ions (I ^- ), iodine molecules (I ₂ ), polyiodine ions (I ₃ ^- , I ₅ ^- ), etc., and the iodine content in this specification is , refers to the amount of iodine including all of these forms. Iodine content can be calculated, for example, by the calibration curve method of fluorescence X-ray analysis. In addition, the polyiodine ion exists in the state of forming a PVA-iodine complex in the polarizer. By forming such a complex, absorption dichroism can be expressed in the wavelength range of visible light. Specifically, the complex of PVA and triiodide ions (PVA·I ₃ ^- ) has an absorption peak around 470 nm, and the complex of PVA and pentaiodide ions (PVA·I ₅ ^- ) has an absorption peak around 600 nm. It has a peak. As a result, polyiodine ions can absorb light in a wide range of visible light depending on their shape. On the other hand, iodine ions (I ^- ) have an absorption peak around 230 nm and are not substantially involved in the absorption of visible light. Therefore, polyiodine ions present in a complex with PVA may be mainly involved in the absorption performance of the polarizer.

The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single transmittance (Ts) of the polarizer is preferably 40% to 48%, and more preferably 41% to 46%. The polarization degree (P) of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more. The single transmittance is typically a Y value measured using an ultraviolet/visible spectrophotometer and subjected to visibility correction. The degree of polarization can be typically obtained by the following equation based on the parallel transmittance (Tp) and orthogonal transmittance (Tc) measured using an ultraviolet/visible spectrophotometer and subjected to visibility correction.

Polarization degree (%)={(Tp-Tc)/(Tp+Tc)} ^1/2 ×100

A polarizer can typically be produced using a laminate of two or more layers. Specific examples of a polarizer obtained using a laminate include a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by applying to the resin substrate is, for example, applied by applying a PVA-based resin solution to a resin substrate, drying it, and forming a PVA-based resin layer on the resin substrate, Obtaining a laminate of a resin substrate and a PVA-based resin layer; It can be produced by stretching and dyeing the laminate and using the PVA-based resin layer as a polarizer. Stretching typically involves immersing the laminate in an aqueous boric acid solution and stretching it. Additionally, stretching may, if necessary, further include air stretching the laminate at a high temperature (for example, 95°C or higher) before stretching in an aqueous boric acid solution. The obtained resin substrate/polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled from the resin substrate/polarizer laminate and applied to the peeled surface for the purpose. Any appropriate protective layer may be laminated and used. Details of the manufacturing method of such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent Application Publication No. 6470455. The entire description of these publications is incorporated herein by reference.

A typical method of manufacturing a polarizer is to form a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate to form a laminate, and to the laminate, It includes carrying out in this order an aerial auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a dry shrink treatment in which the material is shrunk by 2% or more in the width direction by heating while conveying in the longitudinal direction. As a result, a polarizer that is extremely thin and has excellent optical properties while suppressing unevenness in optical properties can be provided. That is, by introducing auxiliary stretching, even when PVA is applied on a thermoplastic resin, it becomes possible to increase the crystallinity of PVA and achieve high optical properties. Moreover, by simultaneously increasing the orientation of PVA in advance, problems such as a decrease in orientation or dissolution of PVA when immersed in water in the subsequent dyeing process or stretching process can be prevented, making it possible to achieve high optical properties. I do it. Additionally, when the PVA-based resin layer is immersed in a liquid, the disruption of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to the case where the PVA-based resin layer does not contain a halide. Thereby, the optical properties of the 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. Additionally, optical properties can be improved by shrinking the laminate in the width direction through dry shrinkage treatment.

B-2. protective layer

The protective layer 12 and the second protective layer (not shown) are each formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of materials that become the main component of the film include cellulose-based resins such as triacetylcellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, Transparent resins such as polysulfone-based, polystyrene-based, cyclic olefin-based (eg, polynorbornene-based), polyolefin-based, (meth)acrylic-based, and acetate-based resins can be mentioned. In addition, thermosetting resins or ultraviolet curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, silicone, etc. may also be included. In addition to these, for example, glassy polymers such as siloxane polymers can also be mentioned. Additionally, the polymer film described in Japanese Patent Application Laid-Open No. 2001-343529 (WO01/37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used, for example, isobutene and A resin composition containing an alternating copolymer made of N-methylmaleimide and an acrylonitrile/styrene copolymer can be mentioned. The polymer film may be, for example, an extrusion molded product of the resin composition.

The laminate according to the embodiment of the present invention is typically disposed on the viewer's side of the image display device, and the protective layer 12 is disposed on the viewer's side. Therefore, the protective layer 12 may be subjected to surface treatment such as hard coat (HC) treatment, anti-reflection treatment, anti-sticking treatment, or anti-glare treatment as needed. Additionally, the protective layer 12 may be treated, as necessary, to improve visibility when viewed through polarized sunglasses (typically, imparting an (other) circularly polarized light function or imparting an ultra-high phase difference. ) may be implemented. By performing such processing, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses, and can also be suitably applied to an image display device that can be used outdoors.

The thickness of the protective layer is preferably 10 μm to 50 μm, more preferably 10 μm to 30 μm. In addition, when surface treatment is performed, the thickness of the protective layer is a thickness including the thickness of the surface treatment layer.

In one embodiment, the second protective layer is preferably optically isotropic. In this specification, 'optically isotropic' 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.

C. Resin layer

The resin layer can reduce the influence that the polarizer may have on other members (can have a barrier function). For example, the movement of iodine that may be contained in the polarizer can be suppressed, and when the laminate is mounted on an image display device, corrosion of the metal member of the image display device can be significantly suppressed. The resin layer is typically a solidified or thermoset product of a coating film of an organic solvent solution of a resin. With this configuration, the thickness can be made very thin (for example, 10 μm or less). The thickness of the resin layer is preferably 5 μm or less, more preferably 1 μm or less, and still more preferably 0.7 μm or less. On the other hand, the thickness of the resin layer is preferably 0.05 μm or more, more preferably 0.08 μm or more, further preferably 0.1 μm or more, and particularly preferably 0.2 μm or more. Moreover, with such a structure, the resin layer can be formed directly on the polarizing plate (polarizer) or the functional layer without interposing the adhesive layer. Such a resin layer has the advantage of excellent humidification durability because it has lower hygroscopicity and moisture permeability than solidified water-based coating films such as, for example, aqueous solutions or water dispersions. As a result, a highly durable laminate that can maintain optical properties even under a high temperature and high humidity environment can be obtained. In addition, such a resin layer can suppress adverse effects on the polarizing plate (polarizer) caused by ultraviolet irradiation compared to, for example, a cured product of ultraviolet curable resin. The resin layer is preferably a solidified product of a coating film of an organic solvent solution of the resin. The solidified product has less shrinkage during film molding than the cured product and does not contain residual monomers, so deterioration of the film itself is suppressed, and it also prevents adverse effects on the polarizer or functional layer due to residual monomers, etc. It can be suppressed.

The glass transition temperature (Tg) of the resin constituting the resin layer is 85°C or higher, and the weight average molecular weight (Mw) is 50,000 or higher. If Tg and Mw are in this range, the resin layer can be included in the polarizer despite being very thin due to a synergistic effect with the effect of forming the resin layer from a solidified product or thermoset of a coating film of an organic solvent solution of the resin. It can significantly inhibit the movement of iodine. The Tg of the resin constituting the resin layer is preferably 90°C or higher, more preferably 100°C or higher, further preferably 110°C or higher, and particularly preferably 120°C or higher. The upper limit of Tg may be, for example, 200°C. Moreover, the Mw of the resin constituting the resin layer is preferably 60,000 or more, more preferably 70,000 or more, and even more preferably 80,000 or more. On the other hand, Mw is preferably less than 500,000, preferably less than 400,000, and more preferably less than 300,000.

The resin layer further contains an isocyanate compound in addition to the above resin. Specifically, as the isocyanate compound, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and their derivatives (e.g., denatured products, adducts) are used. These may be used individually or in combination. By using such an isocyanate compound, excellent adhesion to a polarizing plate (polarizer) can be achieved. As the isocyanate compound, it is preferable to use at least one of hexamethylene diisocyanate or its derivative in addition to the above. According to this configuration, the adhesiveness with the adhesive layer described later can be more excellent.

The content of the resin in the resin layer is, for example, 50% by weight or more, may be 55% by weight or more, and may be 60% by weight or more. On the other hand, the content of the resin in the resin layer is, for example, 90% by weight or less, may be 85% by weight or less, and may be 80% by weight or less. The content of the isocyanate compound in the resin layer is, for example, 10% by weight or more, may be 15% by weight or more, and may be 20% by weight or more. On the other hand, the content of the isocyanate compound in the resin layer is, for example, 50% by weight or less, may be 45% by weight or less, and may be 40% by weight or less. The amount of hexamethylene diisocyanate and its derivatives used relative to 100 parts by weight of the isocyanate compound is preferably 10 parts by weight to 40 parts by weight.

As the resin constituting the resin layer, any suitable thermoplastic resin or thermosetting resin can be used as long as it can form a solidified product or thermoset of a coating film of an organic solvent solution and has the Tg and Mw as described above. Preferably, it is a thermoplastic resin. Examples of thermoplastic resins include epoxy resins and acrylic resins. A combination of epoxy resin and acrylic resin may be used. Hereinafter, representative examples of epoxy resin and acrylic resin that can be used in the resin layer will be described.

<Epoxy Resin>

As the epoxy resin, an epoxy resin having an aromatic ring is preferably used. By using an epoxy resin having an aromatic ring as an epoxy resin, excellent adhesion to a polarizing plate (polarizer) can be achieved. Examples of the epoxy resin having an aromatic ring include bisphenol-type epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, and bisphenol S-type epoxy resin; Novolak-type epoxy resins such as phenol novolak epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; Polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone, and epoxidized polyvinyl phenol, naphthol type epoxy resin, naphthalene type epoxy resin, and biphenyl type epoxy resin. etc. can be mentioned. 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.

<Acrylic resin>

Acrylic resin typically contains a repeating unit derived from a (meth)acrylic acid ester monomer 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 appropriate copolymerization monomer depending on the purpose. Examples of copolymerization monomers 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 predetermined Tg and Mw can be obtained.

<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 but less than 50 parts by weight of the monomer represented by formula (1) (hereinafter sometimes referred to as a copolymerized monomer). It includes a copolymer (hereinafter sometimes referred to as boron-containing acrylic resin) obtained by polymerizing a monomer mixture of the following:

(Wherein, represents a functional group containing at least one type of reactive group, and R ¹ and R ² are each independently a hydrogen atom, an aliphatic hydrocarbon group that may have a substituent, an aryl group that may have a substituent, or It represents a heterocyclic group, and R ¹ and R ² may be connected to each other to form a ring).

Boron-containing acrylic resin typically has a repeating unit represented by the following formula. By polymerizing a monomer mixture containing a copolymerization monomer 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, the repeating unit of k in the formula below). Thereby, excellent adhesion to the polarizing plate (polarizer) can be achieved. This boron-containing substituent may be included continuously (i.e., in a block shape) or randomly in the boron-containing acrylic resin.

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

<(meth)acrylic monomer>

As the (meth)acrylic monomer, any suitable (meth)acrylic monomer can be used. For example, (meth)acrylic acid ester monomers having a straight chain or branched structure, and (meth)acrylic acid ester monomers having a cyclic structure.

Examples of (meth)acrylic acid ester monomers having a straight chain or branched structure include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and n- (meth)acrylate. Butyl, 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 monomer may be used alone or in combination of two or more types.

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, and dimethyl (meth)acrylate. Clopentenyl, dicyclopentenyl oxyethyl (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- Biphenyl groups such as (meth)acryloyloxyethyl-p-biphenyl-carbamate, N-(meth)acryloyloxyethyl-m-biphenyl-carbamate, and o-phenylphenol glycidyl ether acrylate. Containing monomers, terphenyl (meth)acrylate, o-terphenyloxyethyl (meth)acrylate, etc. are mentioned. Preferably, 1-adamantyl (meth)acrylate and dicyclofentanyl (meth)acrylate are used. By using these monomers, a polymer with a high glass transition temperature is obtained. These monomers may be used alone or in combination of two or more types.

Additionally, instead of the (meth)acrylic acid ester monomer, a silsesquioxane compound having a (meth)acryloyl group may be used. By using a silsesquioxane compound, an acrylic polymer with a high glass transition temperature is obtained. Silsesquioxane compounds are known to have various skeletal structures, such as basket-like structures, ladder-like structures, and random structures. The silsesquioxane compound may have only one type or 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 a silsesquioxane compound containing a (meth)acryloyl group, for example, MAC grade and AC grade of Toagosei Co., Ltd. SQ series can be used. MAC grade is a silsesquioxane compound containing a methacryloyl group, and specifically, examples include MAC-SQTM-100, MAC-SQSI-20, MAC-SQHDM, etc. AC grade is a silsesquioxane compound containing an acryloyl group, and specific examples include AC-SQTA-100 and AC-SQSI-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.

<Copolymerization monomer>

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

Examples of the aliphatic hydrocarbon group in the formula (1) include a straight-chain or branched alkyl group of 1 to 20 carbon atoms that may have a substituent, a cyclic alkyl group of 3 to 20 carbon atoms that may have a substituent, and an alkenyl group of 2 to 20 carbon atoms. You can. 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 group or a 6-membered group containing at least one heteroatom that may have a substituent. Additionally, 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 straight-chain or branched alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom.

The reactive group contained in the functional group represented by It is at least one type selected from the group consisting of: Preferably, the reactive group is a (meth)acryl group and/or a (meth)acrylamide group. By having these reactive groups, excellent adhesion to a polarizing plate (polarizer) can be achieved.

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

As a copolymerization monomer, the following compounds can be specifically used.

The copolymerization monomer is used in an amount of more than 0 parts by weight and less than 50 parts by weight, based on 100 parts by weight of the monomer mixture. It 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 0.5 parts by weight to 5 parts by weight. am.

<Acrylic resin containing lactone ring, etc.>

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

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

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. Additionally, the organic moiety may contain oxygen atoms. The acrylic resin may contain only a single lactone ring unit, or may contain a plurality of lactone ring units in which R ² , R ³ and R ⁴ in the general formula (2) are different. Acrylic resins having lactone ring units are described, for example, in Japanese Patent Application Laid-Open No. 2008-181078, the description of which is incorporated herein by reference.

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

In general formula (3), R ¹¹ and R ¹² each independently represent hydrogen or an alkyl group with 1 to 8 carbon atoms, and R ¹³ represents an alkyl group with 1 to 18 carbon atoms, a cycloalkyl group with 3 to 12 carbon atoms, or a carbon number. It represents an aryl group of 6 to 10. 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 a plurality of glutarimide units in which R ¹¹ , R ¹² and R ¹³ in the general formula (3) are different. Acrylic resins having a glutarimide unit include, for example, Japanese Patent Application Laid-Open No. 2006-309033, Japanese Patent Application Publication No. 2006-317560, Japanese Patent Application Publication No. 2006-328334, Japanese Patent Application Publication No. 2006-337491, and Japanese Patent Application Publication No. 2006-337491. It is described in Patent Publication No. 2006-337492, Japanese Patent Application Publication No. 2006-337493, and Japanese Patent Application Publication No. 2006-337569, and the descriptions of these publications are incorporated herein by reference. In addition, for the glutaric anhydride unit, the above explanation regarding the glutarimide unit applies, except that the nitrogen atom substituted by R ¹³ in the general formula (3) above becomes an oxygen atom.

Regarding the maleic anhydride unit and maleimide (N-substituted maleimide) unit, the structure is specified from the name, so detailed description is omitted.

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

The resin layer can typically be formed by applying an organic solvent solution of the resin to form a coating film and solidifying or heat-curing the resulting coating film. As the organic solvent, any suitable organic solvent capable of dissolving or uniformly dispersing the 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 parts by weight 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, but is preferably applied to a polarizing plate (polarizer) or a functional layer. When applying a solution to a substrate, the resin layer formed on the substrate is typically transferred to a polarizing plate (polarizer) or a functional layer. Since transfer is typically performed through an adhesive layer, the resin layer can be formed directly by applying the solution to a polarizing plate (polarizer) or a functional layer, and the adhesive layer can be omitted. As a method of applying the solution, any suitable method can be adopted. Specific examples include roll coat method, spin coat method, wire bar coat method, dip coat method, die coat method, curtain coat method, spray coat method, and knife coat method (comma coat method, etc.).

The heating temperature for solidification or heat curing of the coating film is preferably 100°C or lower, and more preferably 50°C to 70°C. If the heating temperature is in this range, adverse effects on the polarizer can be prevented. The heating time may be, for example, 1 minute to 10 minutes.

The resin layer (substantially an organic solvent solution of the resin) may contain any appropriate additives depending on the purpose. Specific examples of additives include ultraviolet absorbers; leveling agent; Antioxidants such as hindered phenol-based, phosphorus-based, and sulfur-based antioxidants; Stabilizers such as light stabilizers, weather stabilizers, and heat stabilizers; Reinforcing materials such as glass fiber and carbon fiber; Near-infrared absorber; Flame retardants such as tris(dibromopropyl)phosphate, triallyl phosphate, and antimony oxide; Antistatic agents such as anionic, cationic, and nonionic surfactants; Colorants such as inorganic pigments, organic pigments, and dyes; Organic or inorganic filler; Resin modifier; Organic or inorganic fillers; plasticizer; lubricant; antistatic agent; Flame retardants, etc. can be mentioned. The type, number, combination, addition amount, etc. of additives can be appropriately set depending on the purpose.

D. Adhesive layer

The adhesive layer is preferably composed of a cured product of the adhesive composition. Specifically, it is preferably composed of a cured product of an active energy ray-curable adhesive composition (radical polymerization-curable adhesive composition) that has electron beam curability, ultraviolet ray curability, or visible light curability. The thickness of the adhesive layer is preferably 3 μm or less, and more preferably 2 μm or less. Such a thickness can greatly contribute to thinning the laminated body. Additionally, the influence on other members due to shrinkage that may occur when forming an adhesive layer from the adhesive composition can be reduced. For example, from the viewpoint of obtaining excellent adhesiveness, the thickness of the adhesive layer is preferably 0.05 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more.

Examples of the monomer component constituting the radical polymerization-curable adhesive composition include compounds having a radically polymerizable functional group of a carbon-carbon double bond, such as a (meth)acryloyl group and a vinyl group. As these monomer components, either a monofunctional radically polymerizable compound or a polyfunctional radically polymerizable compound having two or more polymerizable functional groups can be used. In addition, these radically polymerizable compounds can be used individually or in combination of two or more types. In addition, in the present invention, (meth)acryloyl means an acryloyl group and/or a methacryloyl group.

The octanol/water partition coefficient logPow calculated by the weighted average of the mole fractions of the monomer components contained in the adhesive composition is, for example, 1.0 or more and 4.0 or less, preferably 1.5 or more, may be 2.0 or more, and may be 2.5 or more. By using such an adhesive composition, excellent adhesion to the resin layer can be obtained. In addition, the function of the resin layer (eg, barrier function) can be maintained. By using such an adhesive composition, the formation of the intermediate layer (commercial layer) can be suppressed. Here, the octanol/water partition coefficient (logPow) is an indicator of the lipophilicity of the material and means the logarithmic value of the octanol/water partition coefficient. A high logPow may mean that it is lipophilic. logPow can be measured (for example, by the flask permeation method described in JIS-Z-7260), but can also be calculated by calculation. In this specification, the octanol/water partition coefficient (logPow) refers to the value calculated with ChemDrawUltra manufactured by Cambridge Soft. For the resin layer, which may be a solidified product or thermoset of a coating film of an organic solvent solution of a resin, the formation of the intermediate layer can be suppressed and excellent adhesiveness can be obtained by using an adhesive composition with high hydrophobicity. It is an unexpected and excellent effect.

The logPow of the radically polymerizable compound is shown below. For example, hydroxyethylacrylamide (brand name 'HEAA', manufactured by Kyojin, LogPow; -0.56), diethylacrylamide (brand name 'DEAA', manufactured by KJ Chemicals, LogPow; 1.69), unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone (product name 'Flaxel FA1DDM', manufactured by Daicel, LogPow; 1.06), N-vinylformamide (product name 'Beamset 770', manufactured by Arakawa Chemical Company, LogPow; -0.25), acryloylmorpholine (product name) 'ACMO', manufactured by Kyojin Corporation, LogPow; -0.20), γ-butyrolactone acrylate (brand name 'GBLA', manufactured by Osaka Organic Chemical Industries, LogPow; 0.19), acrylic acid dimer (brand name 'β-CEA', Daicel Corporation) Manufactured by LogPow; 0.2), N-vinylpyrrolidone (trade name 'NVP', manufactured by Nippon Shokubai Co., Ltd., LogPow; 0.24), acetoacetoxyethyl methacrylate (trade name 'AAEM', manufactured by Nippon Synthetic Chemical Co., Ltd., LogPow; 0.27), 2-hydroxyethyl acrylate (brand name 'HEA', manufactured by Osaka Organic Chemicals, LogPow; 0.28), glycidyl methacrylate (brand name 'Light Ester G', manufactured by Kyoeisha Chemical Co., Ltd., LogPow; 0.57) ), dimethylacrylamide (brand name 'DMAA', manufactured by Kyojin Co., Ltd., LogPow; 0.58), tetrahydrofurfuryl alcohol acrylic acid multimer ester (brand name 'Viscott #150D', manufactured by Osaka Organic Chemicals Co., Ltd., LogPow; 0.60), 4 -Hydroxybutylacrylate (brand name '4-HBA', manufactured by Osaka Organic Chemicals, LogPow; 0.68), acrylic acid (brand name 'Acrylic Acid', manufactured by Mitsubishi Chemical Corporation, LogPow; 0.69), triethylene glycol diacrylate (brand name ' Light Acrylate 3EG-A', manufactured by Kyoeisha Chemical Co., Ltd., LogPow; 0.72), PEG400# diacrylate (product name 'Light Acrylate 9EG-A', manufactured by Kyoeisha Chemical Co., Ltd., LogPow; -0.1), polypropylene glycol Diacrylate (product name 'Aronix M-220', manufactured by Toa Gosei, LogPow; 1.68), dicyclopentenyl acrylate (brand name 'Pancryl FA-511AS', manufactured by Hitachi Chemical Company, LogPow; 2.26), butyl acrylate (brand name 'Butyl Acrylate', manufactured by Mitsubishi Chemical Corporation, LogPow; 2.35), 1,6 -Hexanediol diacrylate (product name 'Light Acrylate 1.6HX-A', manufactured by Kyoeisha Chemical Company, LogPow; 2.43), dicyclopentanyl acrylate (product name 'Pancryl FA-513AS', manufactured by Hitachi Chemical Company, LogPow) ; 2.58), dimethyloltricyclodecane diacrylate (product name 'Light Acrylate DCP-A', manufactured by Kyoeisha Chemical Co., Ltd., LogPow; 3.05), isobornyl acrylate (product name 'Light Acrylate IB-XA', manufactured by Kyoeisha Chemical Co., Ltd. Eisha Chemical Co., Ltd., LogPow; 3.27), hydroxypivalic acid neopentyl glycol acrylic acid adduct (product name 'Light Acrylate HPP-A', Kyoeisha Chemical Co., Ltd., LogPow; 3.35), 1,9-nonanediol diacryl Rate (brand name 'Light Acrylate 1,9ND-A', manufactured by Kyoeisha Chemical Co., Ltd., LogPow; 3.68), o-phenylphenol EO modified acrylate (brand name 'Pancryl FA-301A', manufactured by Hitachi Chemical Co., Ltd., LogPow; 3.98), 2-ethylhexyloxetane (product name 'Alon Oxetane OXT-212', manufactured by Toa Gosei, LogPow; 4.24), bisphenol-A-diglycidyl ether (product name 'JER828', manufactured by Mitsubishi Chemical Corporation, LogPow) ; 4.76), Bisphenol A-EO 6 mol modified diacrylate (Product name 'FA-326A', Hitachi Chemical Co., Ltd., LogPow; 4.84), Bisphenol A-EO 4 mol modified diacrylate (Product name 'FA-324A', Hitachi Chemical Co., Ltd. manufactured by Hitachi Chemical Co., Ltd., LogPow; 5.15), bisphenol APO 2 mole modified diacrylate (product name 'FA-P320A', manufactured by Hitachi Chemical Company, LogPow; 6.10), bisphenol APO 3 mole modified diacrylate (product name 'FA-P323A') ', manufactured by Hitachi Chemical Company, LogPow; 6.26), bisphenol APO 4 mole modified diacrylate (product name 'FA-P324A', manufactured by Hitachi Chemical Company, LogPow; 6.43), lauryl acrylate (brand name 'Light Acrylate L-A', manufactured by Kyoeisha Chemical Co., Ltd., LogPow; 6), isostearyl acrylate (brand name 'ISTA'), manufactured by Osaka Organic Chemicals Co., Ltd.; LogPow; 7.46), Phenoxydiethylene glycol acrylate (Product name 'P2HA', manufactured by Kyoeisha Chemical Co., Ltd., LogPow; 2.15), 2-hydroxy-3-phenoxypropyl acrylate (Product name 'Aronics M-5700', Toa Gosei) Director Manufacturing, LogPow; 1.17).

When the total amount of monomer components contained in the adhesive composition is 100 parts by weight, the content of the monomer component whose octanol/water partition coefficient logPow is 0.0 or less may be 30 parts by weight or less. When the total amount of monomer components contained in the adhesive composition is 100 parts by weight, the content of the monomer component having an octanol/water partition coefficient logPow of 2.0 or more may be 40 parts by weight or more.

The blending amount of the polymerization initiator that can be used during curing is, for example, 0.05% by weight to 10% by weight when the total amount of the adhesive composition is 100% by weight.

Curing of the adhesive composition is performed, for example, by irradiating an active energy ray (eg, visible light, ultraviolet ray, or electron beam) to the coating film of the adhesive composition.

E. Phase contrast layer

The phase difference layer may be a single layer or may have a laminated structure of two or more layers. The retardation layer may be composed of any suitable material. Specifically, the retardation layer may be an alignment-fixed layer of a liquid crystal compound, a stretched film (resin film), or a combination thereof. The thickness of the retardation layer is, for example, 1 μm or more and 50 μm or less. In one embodiment, the thickness of the retardation layer is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 6 μm or less. According to the embodiment of the present invention, even in the case where an extremely thin retardation layer is used, for example, when the laminate is mounted on an image display device, corrosion of the metal member of the image display device can be significantly suppressed. Additionally, when the retardation layer has a laminated structure, 'thickness of the retardation layer' means the sum of the thicknesses of each retardation layer. Specifically, the ‘thickness of the phase contrast layer’ does not include the thickness of the adhesive layer.

As the phase difference layer, for example, an alignment-fixed layer of a liquid crystal compound (liquid crystal alignment-fixed layer) is used. By using a liquid crystal compound, for example, the difference between nx and ny of the resulting retardation layer can be significantly increased compared to a non-liquid crystal material, so the thickness of the retardation layer for obtaining the desired in-plane retardation can be significantly reduced. Therefore, it is possible to realize significant thinning of the polarizing plate with a retardation layer. In this specification, the term 'alignment-fixed layer' refers to a layer in which a liquid crystal compound is oriented in a predetermined direction within the layer, and its orientation state is fixed. In addition, the 'alignment solidified layer' is a concept that includes an alignment hardened layer obtained by curing a liquid crystal monomer, as will be described later. In the phase contrast layer, typically, rod-shaped liquid crystal compounds are oriented in a line in the slow axis direction of the phase contrast layer (homogeneous orientation).

The liquid crystal alignment solidification layer applies an orientation treatment to the surface of a predetermined substrate, applies a coating liquid containing a liquid crystal compound to the surface, orients the liquid crystal compound in a direction corresponding to the orientation treatment, and maintains the orientation state. It can be formed by fixing . As the orientation treatment, any appropriate orientation treatment may be employed. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be mentioned. Specific examples of mechanical orientation treatment include rubbing treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include oblique vapor deposition and photo-alignment treatment. The treatment conditions for various orientation treatments may be any appropriate conditions depending on the purpose.

The liquid crystal compound is aligned by treating it at a temperature that exhibits a liquid crystal phase depending on the type of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound assumes a liquid crystal state, and the liquid crystal compound is aligned according to the orientation treatment direction of the substrate surface.

In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the alignment state is fixed by subjecting the liquid crystal compound oriented as described above to polymerization treatment or crosslinking treatment.

Specific examples of the liquid crystal compound and details of the method for forming the alignment solidification layer are described in Japanese Patent Application Laid-Open No. 2006-163343. The description in this publication is incorporated herein by reference.

In one embodiment when the retardation layer is a single layer, the retardation layer can function as a λ/4 plate. Specifically, Re(550) of the retardation layer is preferably 100 nm to 180 nm, more preferably 110 nm to 170 nm, and still more preferably 110 nm to 160 nm. The thickness of the retardation layer can be adjusted to obtain the desired in-plane retardation of the λ/4 plate. When the retardation layer is the above-mentioned liquid crystal alignment solidification layer, its thickness is, for example, 1.0 μm to 2.5 μm. In this embodiment, the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably 44° to 46°. am. Additionally, the phase difference layer preferably exhibits inverse dispersion wavelength characteristics in which the phase difference value increases depending on the wavelength of the measurement light.

In another embodiment where the phase difference layer is a single layer, the phase difference layer can function as a λ/2 plate. Specifically, Re(550) of the phase contrast layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and even more preferably 230 nm to 280 nm. The thickness of the retardation layer can be adjusted to obtain the desired in-plane retardation of the λ/2 plate. When the retardation layer is the above-mentioned liquid crystal alignment solidification layer, its thickness is, for example, 2.0 μm to 4.0 μm. In this embodiment, the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably 12° to 16°. am.

In one embodiment when the retardation layer has a laminated structure, the retardation layer has a two-layer laminated structure in which the first retardation layer (H layer) and the second retardation layer (Q layer) are arranged in order from the polarizer side. has The H layer can typically function as a λ/2 plate, and the Q layer can typically function as a λ/4 plate. Specifically, Re(550) of the H layer is preferably 200 nm to 300 nm, more preferably 220 nm to 290 nm, and still more preferably 230 nm to 280 nm; Re(550) of the Q layer is preferably 100 nm to 180 nm, more preferably 110 nm to 170 nm, and still more preferably 110 nm to 150 nm. The thickness of the H layer can be adjusted to obtain the desired in-plane retardation of the λ/2 plate. When the H layer is the above-mentioned liquid crystal alignment solidification layer, its thickness is, for example, 2.0 μm to 4.0 μm. The thickness of the Q layer can be adjusted to obtain the desired in-plane retardation of the λ/4 plate. When the Q layer is the above-mentioned liquid crystal alignment solidification layer, its thickness is, for example, 1.0 μm to 2.5 μm. In this embodiment, the angle formed by the slow axis of the H layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably 12° to 16°. ego; The angle formed between the slow axis of the Q layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and still more preferably 72° to 76°. Additionally, the arrangement order of the H layer and the Q layer may be reversed, and the angle formed by the slow axis of the H layer and the absorption axis of the polarizer and the angle formed by the slow axis of the Q layer and the absorption axis of the polarizer may be reversed. In addition, each layer (e.g., H layer and Q layer) may exhibit inverse dispersion wavelength characteristics in which the phase difference value increases depending on the wavelength of the measurement light, or may exhibit a positive wavelength characteristic in which the phase difference value decreases depending on the wavelength of the measurement light. Dispersion characteristics may be displayed, or flat wavelength dispersion characteristics in which the phase difference value hardly changes depending on the wavelength of the measurement light may be displayed.

The refractive index characteristic of the retardation layer (at least one layer when it has a laminated structure) typically shows the relationship nx>ny=nz. Additionally, 'ny=nz' includes not only the case where ny and nz are completely the same, but also the case where they are substantially the same. Therefore, there may be cases where ny > nz or ny < nz within a range that does not impair the effect of the present invention. The Nz coefficient of the phase difference layer is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3.

As mentioned above, the retardation layer is preferably a liquid crystal alignment solidification layer. Examples of the liquid crystal compound include a liquid crystal compound (nematic liquid crystal) whose liquid crystal phase is a nematic phase. As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The mechanism for expressing liquid crystallinity of the liquid crystal compound may be lyotropic or thermotropic. The liquid crystal polymer and liquid crystal monomer may be used individually or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer or a crosslinkable monomer. This is because the alignment state of the liquid crystal monomer can be fixed by polymerizing or crosslinking (i.e., curing) the liquid crystal monomer. After aligning the liquid crystal monomers, for example, by polymerizing or crosslinking the liquid crystal monomers, the alignment state can be fixed accordingly. Here, polymers are formed by polymerization and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, the formed retardation layer is unlikely to transition into a liquid crystal phase, a glass phase, or a crystal phase due to temperature changes peculiar to liquid crystalline compounds, for example. As a result, the phase difference layer becomes a phase difference layer that is not affected by temperature changes and has extremely excellent stability.

The temperature range where a liquid crystal monomer exhibits liquid crystallinity varies depending on its type. Specifically, the temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and most preferably 60°C to 90°C.

As the liquid crystal monomer, any suitable liquid crystal monomer may be employed. For example, those described in Japanese Patent Application Publication 2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171, and GB2280445. Polymerizable mesogenic compounds, etc. can be used. Specific examples of such polymerizable mesogenic compounds include, for example, BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Sillicon-CC3767. As the liquid crystal monomer, a nematic liquid crystal monomer is preferable.

In another embodiment, the retardation layer includes, from the polarizer side, a first retardation layer capable of functioning as a λ/4 plate and a second retardation layer whose refractive index characteristic exhibits the relationship of nz>nx=ny (so-called positive C plate). It has a layered structure. Details of the λ/4 version are as described above. In this embodiment, the angle formed by the slow axis of the first retardation layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably 44° to 44°. It is 46°. Additionally, the first phase difference layer preferably exhibits inverse dispersion wavelength characteristics in which the phase difference value increases depending on the wavelength of the measurement light.

The phase difference Rth (550) in the thickness direction of the positive C plate is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, even more preferably -90 nm to -200 nm, and especially preferably is -100nm~-180nm. Here, 'nx=ny' includes not only the case where nx and ny are strictly the same, but also the case where nx and ny are substantially the same. The in-plane retardation Re(550) of the positive C plate is, for example, less than 10 nm.

The second retardation layer having a refractive index characteristic of nz>nx=ny may be formed of any suitable material, but preferably comprises a film comprising a liquid crystal material fixed in homeotropic orientation. The liquid crystal material (liquid crystal compound) capable of homeotropic alignment may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compound and the method for forming the retardation layer described in [0020] to [0028] of Japanese Patent Application Laid-Open No. 2002-333642. In this case, the thickness of the second phase difference layer is preferably 0.5 μm to 5 μm.

F. Image display device

The laminate can be applied to an image display device. Therefore, an image display device according to an embodiment of the present invention includes the above laminate. Representative examples of image display devices include liquid crystal display devices and electroluminescence (EL) display devices (eg, organic EL display devices and inorganic EL display devices).

FIG. 2 is a cross-sectional view schematically showing the schematic configuration of an image display panel included in an image display device according to one embodiment of the present invention, taking an organic EL display device as an example. The image display panel (organic EL panel) 200 includes an organic panel main body 70 and a laminate 100 disposed on the viewer side thereof. The laminate 100 is arranged so that the resin layer 20 is closer to the organic EL panel main body 70 than the polarizer 11. Typically, the laminate 100 is attached to the organic EL panel main body 70 with an adhesive layer (not shown).

The organic EL panel main body 70 includes a substrate 71, a circuit layer including a thin film transistor (TFT), an organic light emitting diode (OLED), and an upper structural layer 72 including an encapsulation film for sealing the OLED. Includes. The upper structural layer 72 may include metal members (eg, electrodes, sensors, wires, metal layers). For example, when a flexible substrate (e.g., a resin substrate) is used as the substrate 71, the resulting organic EL display device can be curved, bent, folded, rolled, etc. Since the laminate according to the embodiment of the present invention can have excellent flexibility and folding durability, it can also be suitably used in such an image display device.

[Example]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measurement methods for thickness, Tg, and Mw are as follows. Additionally, unless otherwise specified, 'part' and '%' in Examples and Comparative Examples are based on weight.

(1) Thickness

The thickness of 10 μm or less was measured using an interference film thickness meter (manufactured by Otsuka Electronics, product name ‘MCPD-3000’). Thickness exceeding 10㎛ was measured using a digital micrometer (manufactured by Anritsu, product name 'KC-351C').

(2) Glass transition temperature (Tg)

Approximately 5 mg of sample (polymer) was collected, DSC measurement was performed under the following conditions, and the midpoint glass transition temperature was calculated from the obtained measurement results.

·Measuring device: manufactured by TA Instruments, product name: Q-2000

·Temperature program: Changes from 0℃→150℃→0℃→150℃

·Atmospheric gas: N ₂ (50mL/min)

·Measurement speed: 10℃/min

(3) Weight average molecular weight (Mw)

It was measured by gel permeation chromatography (GPC) and calculated as a standard polystyrene conversion value.

·Analysis device: HLC-8120GPC manufactured by Tosoh Corporation

Column: manufactured by Tosoh Corporation, G7000HXL＋GMHXL＋GMHXL

·Column size: 7.8mmϕ×30cm each, 90cm in total

·Column temperature: 40℃

·Flow rate: 0.8ml/min

·Injection volume: 100μl

·Eluent: Tetrahydrofuran

Detector: Differential refractometer (RI)

·Standard sample: polystyrene

[Example 1]

(Production of polarizer)

As a thermoplastic resin substrate, an amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) with a long shape, water absorption of 0.75%, and Tg of about 75°C was used. Corona treatment was performed on one side of the resin substrate.

100 parts by weight of PVA-based resin mixed at a ratio of 9:1 with polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Japan Synthetic Chemical Industry Co., Ltd., product name 'Kosefimer Z410'), potassium iodide 13 parts by weight was dissolved in water to prepare a PVA aqueous solution (coating solution).

The PVA aqueous solution was applied to the corona-treated surface of the resin substrate 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 free-end uniaxially stretched 2.4 times in the machine direction (longitudinal direction) between rolls with different circumferential speeds in an oven at 130°C (air auxiliary stretching treatment).

Next, the laminate was immersed in an insolubilization bath (boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) with a liquid temperature of 40°C for 30 seconds (insolubilization treatment).

Next, in a dyeing bath (iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30°C, the final polarizer has a single transmittance (Ts) of 43.0% or more. It was immersed for 60 seconds while adjusting the concentration to achieve this (dyeing treatment).

Next, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by mixing 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 for 30 seconds (crosslinking treatment).

Thereafter, the laminate was immersed in an aqueous solution of boric acid (boric acid concentration: 4.0% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70°C, while the total stretch ratio was stretched in the longitudinal direction (longitudinal direction) between rolls with different circumferential speeds. Uniaxial stretching was performed to increase the size by 5.5 times (underwater stretching treatment).

Thereafter, the laminate was immersed in a washing bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 20°C (washing treatment).

Afterwards, it was dried in an oven maintained at 90°C and brought into contact with a heating roll made of SUS whose surface temperature was maintained at 75°C for about 2 seconds (dry shrink treatment). The shrinkage rate in the width direction of the laminate by dry shrinkage treatment was 5.2%.

In this way, a polarizer with a thickness of 5 μm was formed on the resin substrate.

(Production of polarizer)

An HC-COP film was bonded as a protective layer to the surface of the polarizer obtained above (the side opposite to the resin substrate) through an ultraviolet curing adhesive. Specifically, an ultraviolet curing adhesive was applied so that the thickness after curing was 1.0 μm, and the adhesive was bonded using a roll machine. Afterwards, UV rays were irradiated from the HC-COP film side to cure the adhesive. In addition, the HC-COP film is a film in which a hard coat (HC) layer (2 ㎛ thick) is formed on a cycloolefin (COP) film (manufactured by Nippon Zeon, product name 'ZF12', thickness 25 ㎛), and the COP film acts as a polarizer. The sides were joined together. Next, the resin substrate was peeled from the polarizer, and a polarizing plate having the structure of protective layer (HC-COP film)/adhesive layer/polarizer was obtained.

(Formation of resin layer)

99.0 parts by weight of methyl methacrylate (MMA, manufactured by Fujifilm Wako Purell, brand name: methyl methacrylate monomer), 1.0 parts by weight of monomer of general formula (1e), polymerization initiator (manufactured by Fujifilm Wako Purell, brand name: 2 , 0.2 parts by weight of 2'-azobis(isobutyronitrile)) was dissolved in 100 parts by weight of toluene. Next, a polymerization reaction was performed for 5.5 hours while heating at 70°C in a nitrogen atmosphere to obtain Copolymer 1 (solid content concentration: 50% by weight). The Tg of copolymer 1 was 105°C and Mw was 85000.

With respect to 70 parts (converted to solid content) of the obtained copolymer 1 (boron-containing acrylic resin), as an isocyanate compound, trimethylolpropane adduct of tolylene diisocyanate (manufactured by Tosoh Corporation, brand name 'Colonate L') was added to 22.5 parts (converted to solid content). A mixture was obtained by adding 7.5 parts of trimethylolpropane adduct of hexamethylene diisocyanate (manufactured by Mitsui Chemicals, brand name 'Takenate D160N') in terms of solid content. This mixture was dissolved in 80 parts of a mixed solvent of ethyl acetate/cyclopentanone (70/30) to obtain a resin solution (20%). This resin solution was applied to the surface of the polarizer side of the polarizing plate obtained above using a wire bar, and the coating film was dried at 60°C for 5 minutes to form a resin layer (thickness 0.4) consisting of a solidified product of the coating film of the organic solvent solution of the resin. ㎛) was formed.

(Preparation of adhesive composition)

Each monomer component was mixed in the mixing ratio shown in Table 1, and an adhesive composition containing 3% by weight of a polymerization initiator (manufactured by BASF, brand name 'Irgacure 907') was obtained. In addition, the monomers shown in Table 1 correspond to the brand names mentioned above.

(Production of phase contrast layer)

10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystalline phase (manufactured by BASF, brand name 'Paliocolor LC242', shown in the formula below), and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF, brand name 'Irgacure 907'). was dissolved in 40 g of toluene to prepare a liquid crystal composition (coating solution).

The surface of the polyethylene terephthalate (PET) film (thickness 38 μm) was rubbed using a rubbing cloth, and orientation treatment was performed. The direction of the orientation treatment was set to be 15° when viewed from the viewer's side with respect to the direction of the absorption axis of the polarizer when bonding to the polarizing plate. The liquid crystal coating liquid was applied to this alignment treated surface using a bar coater, and the liquid crystal compound was aligned by heating and drying at 90°C for 2 minutes. The liquid crystal layer formed in this way was irradiated with light at 1 mJ/cm ² using a metal halide lamp to cure the liquid crystal layer, thereby forming a liquid crystal alignment solidification layer A (H layer) on the PET film. The thickness of the liquid crystal alignment solidification layer A was 2.5 μm, and the in-plane retardation Re(550) was 270 nm. In addition, the liquid crystal alignment solidification layer A showed the refractive index characteristic of nx>ny=nz.

A liquid crystal alignment solidification layer B (Q layer) was formed on the PET film in the same manner as above except that the coating thickness was changed and the orientation treatment direction was 75° when viewed from the viewer's side with respect to the direction of the absorption axis of the polarizer. did. The thickness of the liquid crystal alignment solidification layer B was 1.5 μm, and the in-plane retardation Re(550) was 140 nm. In addition, the liquid crystal alignment solidification layer B showed the refractive index characteristic of nx>ny=nz.

(Production of laminate)

The liquid crystal alignment solidification layer A was transferred to the resin layer surface of the polarizing plate on which the resin layer was formed using the adhesive composition so that the thickness of the adhesive layer formed after curing was 1.5 μm. At this time, transfer (lamination) was performed so that the angle formed between the absorption axis of the polarizer and the slow axis of the liquid crystal alignment solidification layer A was 15°. In addition, curing of the adhesive composition was performed by irradiating ultraviolet rays in a nitrogen atmosphere so that the accumulated light amount was 900 mJ/cm ² .

Next, the liquid crystal alignment solidification layer B was transferred to the surface of the liquid crystal alignment solidification layer A using an ultraviolet curing adhesive (thickness after curing: 1 μm). At this time, transfer (lamination) was performed so that the angle formed between the absorption axis of the polarizer and the slow axis of the liquid crystal alignment solidification layer B was 75°. In addition, curing of the adhesive composition was performed by irradiating ultraviolet rays.

In addition, each transfer was performed while roll conveying.

[Example 2 and Example 4]

A laminate was obtained in the same manner as in Example 1, except that the monomer components contained in the adhesive composition were changed as shown in Table 1 below.

[Example 3]

When forming the resin layer, a laminate was obtained in the same manner as in Example 2 except that poly(methyl methacrylate) (manufactured by Merck & Co., Ltd.) with a Tg of 110°C and an Mw of 350,000 was used instead of Copolymer 1. .

[Example 5]

At the time of forming the resin layer, a laminate was obtained in the same manner as in Example 4 except that the isocyanate compound was changed as shown in Table 1.

[Comparative Example 1, Comparative Example 2 and Comparative Example 3]

A laminate was obtained in the same manner as in Example 1, except that the monomer components contained in the adhesive composition were changed as shown in Table 1 below.

[Comparative Example 4]

When forming the resin layer, a laminate was obtained in the same manner as in Example 4 except that poly(methyl methacrylate) (manufactured by Merck & Co., Ltd.) with a Tg of 115°C and a Mw of 1,000,000 was used instead of Copolymer 1. .

[Comparative Example 5]

A laminate was obtained in the same manner as in Example 4 except that an isocyanate compound was not used when forming the resin layer.

For Examples and Comparative Examples, the following evaluation was performed. The evaluation results are summarized in Table 1 along with various values.

<Evaluation>

1. Cross-sectional observation

The cross section of the obtained laminate was observed using a scanning electron microscope (magnification: 30,000 times) to confirm whether or not a compatible layer between the resin layer and the adhesive layer was formed.

[Evaluation standard]

Good: A clear interface exists between the resin layer and the adhesive layer, and no commercial layer is identified.

Bad: There is no clear interface between the resin layer and the adhesive layer, and a commercial layer is confirmed.

2. Peelability

A sample was cut to a size of 200 mm in the longitudinal direction (stretching direction of the polarizer) and 15 mm in the width direction from the obtained laminate, bonded to a glass plate using an adhesive, and then cut with a cutter knife near the area between the resin layer and the adhesive layer. The peeling force (N/15mm) when the polarizing plate was peeled in the longitudinal direction at a peeling speed of 1000 mm/min in a 90 degree direction was measured using Tensiron universal tester RTC (manufactured by A&D Co., Ltd.). Specifically, the peeling force (adhesion force) of the adhesive layer (laminated portion of the adhesive layer and retardation layer) with respect to the resin layer was measured. In addition, the measurement was conducted in an environment of 23°C and 50%RH.

[Table 1]

In each example, excellent adhesion is confirmed. As shown in Fig. 3, in each example, a compatible layer between the resin layer and the adhesive layer was not confirmed. In Figure 3, the interface between a resin layer with a thickness of 0.4 μm and an adhesive layer with a thickness of 1.5 μm can be confirmed. On the other hand, in Comparative Example 1, Comparative Example 2, and Comparative Example 3, a commercial layer was confirmed as shown in FIG. 4. In Figure 4, there is no clear interface between the polarizer (upper side) and the retardation layer (lower side), and a commercial layer with a thickness of 1.9 μm can be confirmed.

The laminate according to the embodiment of the present invention can be used, for example, in an image display device. Representative image display devices include liquid crystal display devices, organic EL display devices, and inorganic EL display devices.

10: Polarizer
11: Polarizer
12: protective layer
20: Resin layer
30: Adhesive layer
40: functional layer
100: Laminate

Claims (9)

It includes a polarizing plate including a polarizer, a functional layer, and a resin layer and an adhesive layer disposed between the polarizing plate and the functional layer,
The resin layer and the adhesive layer are disposed adjacent to each other,
The resin layer includes a resin having a glass transition temperature of 85° C. or higher and a weight average molecular weight Mw of 50,000 to 500,000, and an isocyanate compound, and the isocyanate compound includes tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate. , and their derivatives, the content of the resin in the resin layer is 50% by weight or more and 90% by weight or less, and the content of the isocyanate compound in the resin layer is 10% by weight or more and 50% by weight. % or less,
The adhesive layer is composed of a cured layer of the adhesive composition, and the octanol/water partition coefficient logPow calculated by the weighted average of the mole fractions of the monomer components contained in the adhesive composition is 1.5 or more and 4.0 or less,
Laminate. According to paragraph 1,
A laminate wherein the content of the monomer component having an octanol/water partition coefficient logPow of 0.0 or less is 30 parts by weight or less with respect to 100 parts by weight of the monomer component contained in the adhesive composition. According to paragraph 1,
The laminate further contains at least one of hexamethylene diisocyanate or a derivative thereof as the isocyanate compound. According to paragraph 1,
A laminate wherein the thickness of the adhesive layer is 3 μm or less. According to paragraph 1,
A laminate wherein the thickness of the resin layer is 1 μm or less. According to paragraph 1,
A laminate wherein the resin layer is disposed adjacent to the polarizer. According to paragraph 1,
A laminate wherein the functional layer is a phase contrast layer. An image display device comprising the laminate according to any one of claims 1 to 7. Forming a resin layer by applying an organic solvent solution containing a resin and an isocyanate compound to a polarizing plate or functional layer containing a polarizer, and
It includes bonding the functional layer or the polarizing plate to the resin layer through an adhesive composition,
The resin has a glass transition temperature of 85°C or higher and a weight average molecular weight Mw of 50,000 to 500,000,
The isocyanate compound includes at least one selected from tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and derivatives thereof,
The content of the resin in the resin layer is 50% by weight or more and 90% by weight or less, and the content of the isocyanate compound in the resin layer is 10% by weight or more and 50% by weight or less,
The octanol/water partition coefficient logPow calculated by the weighted average of the mole fractions of the monomer components contained in the adhesive composition is 1.5 or more and 4.0 or less,
Method for manufacturing a laminate.