TW202311039A - Optical laminate - Google Patents

Abstract

The present invention provides an optical laminate including a polarizer in which iodine is adsorbed and oriented, and the optical laminate suppresses the rising of iodine concentration in an adhesive layer laminated thereon. The optical laminate provided by the present invention includes: a polarizing plate including a polarizer, and an optical functional layer including at least one adhesive layer, wherein the polarizing plate is a polyvinyl alcohol resin film in which iodine is adsorbed and oriented, and the adhesive layer contains a total of 1% by mass or more and 10% by mass or less of low-molecular-weight components having molecular weight of 500 or less.

Description

Optical laminate

The present invention relates to an optical laminate.

A polarizer is one of the optical components constituting a display device such as a liquid crystal display device or an organic EL display device, and it is known to use a polyvinyl alcohol-based resin film having iodine adsorbed and oriented. In touch panel display devices mainly used in mobile information terminals such as smartphones and tablet computers, a conductive layer for forming a touch sensor is sometimes installed on an image display element. When the polarizer is incorporated into a touch panel display device, the laminate containing the polarizer is provided with an adhesive (pressure-sensitive adhesive, also known as pressure-sensitive adhesive or pressure-sensitive adhesive) layer. A laminate of agent layers may be bonded such that the adhesive layer directly contacts the conductive layer (for example, Patent Document 1).

[Prior Art Literature]

[Patent Document]

Japanese Patent Laid-Open No. 2015-052765

In the laminate with the adhesive layer attached, the iodine contained in the polarizer may migrate to the adhesive layer to increase the concentration of iodine in the adhesive layer. The migration of iodine is particularly prone to occur in high temperature and high humidity environment. When the conductive layer is a metal layer, when the iodine concentration in the adhesive layer in contact with the conductive layer increases, problems such as corrosion of the metal electrode are likely to occur.

The object of the present invention is to suppress an increase in iodine concentration in an adhesive layer laminated on the optical laminate in an optical laminate containing a polarizer having iodine adsorbed and aligned.

The present invention provides optical layered bodies exemplified below.

[1] An optical laminate comprising: a polarizing plate including a polarizer, and an optical functional layer including at least one adhesive layer, wherein,

The aforementioned polarizer is a polyvinyl alcohol-based resin film with iodine adsorbed and oriented.

The said adhesive layer contains the low molecular weight component whose molecular weight is 500 or less in total at 1 mass % or more and 10 mass % or less.

[2] The optical laminate according to [1], wherein

The aforementioned optical functional layer includes: a first retardation layer and a second retardation layer containing a cured product of a polymerizable liquid crystal compound,

At least one layer of the adhesive layer is laminated between the first retardation layer and the second retardation layer.

[3] The optical laminate according to [1] or [2], wherein

The aforementioned adhesive layer is a hardened layer of an active energy ray curable adhesive,

The aforementioned low-molecular-weight components include unpolymerized monomers of the aforementioned active energy ray-curable adhesive.

[4] The optical laminate according to any one of [1] to [3], wherein the low molecular weight component is selected from the group consisting of monomers having an epoxy group, monomers having an oxetane ring, At least one member of the group consisting of a monomer having an acryloxy group and a monomer having a methacryloxy group.

[5] The optical laminate according to any one of [1] to [4], wherein the polarizing plate has a protective film on one or both sides of the polarizing plate.

[6] The optical laminate according to [5], wherein the polarizing plate has the protective film on the side of the optical function layer of the polarizing plate,

The moisture permeability of the aforementioned protective film at a temperature of 40°C and a relative humidity of 90%RH is above 350g/(m ² ‧24hr).

[7] The optical laminate according to any one of [1] to [6], wherein the luminescence factor corrected single transmittance Ty of the polarizing plate at a wavelength of 550 nm is 43.5% or more.

[8] The optical laminate according to any one of [1] to [7], further comprising an adhesive layer laminated on the surface of the optical functional layer opposite to the polarizing plate.

According to the present invention, even in an optical layered body including a polarizer having adsorbed and aligned iodine, an increase in the concentration of iodine in the adhesive layer laminated on the optical layered body can be suppressed.

10: polarizer

11: Polarizer

12,13: Protective film

20:Optical functional layer

21: The first retardation layer

22: The second retardation layer

23,24: Bonding layer

30: Adhesive layer

40: metal layer

100,200,300,400: optical laminates

FIG. 1 is a cross-sectional view schematically showing an example of an optical layered body according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view schematically showing another example of the optical layered body according to the embodiment of the present invention.

Fig. 3 is a cross-sectional view schematically showing another example of an optical laminate according to an embodiment of the present invention.

Fig. 4 is a cross-sectional view schematically showing another example of the optical layered body according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all the drawings below, in order to facilitate the understanding of each constituent element, the scale is appropriately adjusted and displayed. The scale of each constituent element shown in the drawings is not necessarily consistent with the actual scale of each constituent element.

<Optical laminate>

1 to 4 are schematic cross-sectional views schematically showing an example of an optical layered body according to this embodiment. The optical laminates 100 , 200 , 300 and 400 of this embodiment have a polarizer 10 and an optical function layer 20 in this order. The polarizer 10 and the optical function layer 20 may be in direct contact with each other. The polarizer 10 includes a polarizer 11 . The polarizer 11 is a polyvinyl alcohol-based resin film on which iodine is adsorbed and oriented.

As shown in FIGS. 1 to 3 , the polarizer 10 can be a single-sided protective polarizer with a protective film 12 on one side of the polarizer 11 . At this time, the polarizer 11 is directly laminated on the optical function layer 20 via the bonding layer 24 . As shown in FIG. 4 , the polarizer 10 may be a double-sided protective polarizer having a protective film 12 and a protective film 13 on both sides of the polarizer 11 .

As shown in FIGS. 1 to 4 , the optical function layer 20 may include two retardation layers, namely a first retardation layer 21 and a second retardation layer 22 . The first retardation layer 21 and the second retardation layer 22 may be laminated via the bonding layer 23 . The polarizer 10 and the optical function layer 20 can be bonded via the bonding layer 24 . The optical function layer 20 includes at least one adhesive layer. Among the bonding layers 23 and 24, one can be an adhesive layer, the other can be an adhesive layer, or both can be an adhesive layer. The optical function layer 20 may also include an adhesive layer. In the optical function layer 20 , it is preferable to make the first retardation layer 21 , the adhesive layer and the second retardation layer 22 contact in order.

In the optical layered body 100 shown in FIG. 1 and the optical layered body 400 shown in FIG. 4 , the first retardation layer 21 and the second retardation layer 22 are laminated via the bonding layer 23 which is an adhesive layer. The first retardation layer 21 and the polarizing plate 10 are laminated through the bonding layer 24 which is an adhesive layer.

In the optical laminated body 200 shown in FIG. 2 , the first retardation layer 21 and the second retardation layer 22 are laminated through the bonding layer 23 belonging to the adhesive layer, and the first retardation layer 21 and the polarizing plate 10 are laminated. It is laminated through the bonding layer 24 which is an adhesive agent layer. In the optical laminate 300 shown in FIG. 3 , the first retardation layer 21 and the second retardation layer 22 are laminated via the bonding layer 23 which is an adhesive layer.

As shown in FIGS. 1 to 4 , the optical function layer 20 may have an adhesive layer 30 . The adhesive layer 30 can be laminated on the surface of the optical function layer 20 opposite to the polarizing plate 10 . The adhesive layer 30 can be laminated on the side of the second retardation layer 22 opposite to the polarizer 10 . The adhesive layer 30 may be disposed in direct contact with the second retardation layer 22 .

The optical laminate 100 sequentially includes a protective film 12 , a polarizer 11 , a first retardation layer 21 , an adhesive layer, a second retardation layer 22 and an adhesive layer 30 . The optical laminate 200 sequentially includes a protective film 12 , a polarizer 11 , an adhesive layer, a first retardation layer 21 , a second retardation layer 22 and an adhesive layer 30 . The optical laminate 300 sequentially includes a protective film 12 , a polarizer 11 , an adhesive layer, a first retardation layer 21 , an adhesive layer, a second retardation layer 22 and an adhesive layer 30 . The optical laminate 400 sequentially includes a protective film 12 , a polarizer 11 , a protective film 13 , a first retardation layer 21 , an adhesive layer, a second retardation layer 22 and an adhesive layer 30 .

As shown in FIGS. 1 to 4 , the metal layer 40 can be laminated on the optical laminates 100 , 200 , 300 and 400 . The metal layer 40 is preferably laminated on the side opposite to the polarizer 10 via the adhesive layer 30 . The metal layer 40 may be disposed in direct contact with the adhesive layer 30 .

In a conventional optical laminate, when the adhesive layer is a hardened layer of a photocurable adhesive, the adhesive can be cured by sufficient light irradiation. Furthermore, the additives added to the adhesive are small amounts. Therefore, the low molecular weight component contained in the adhesive layer after hardening is usually less than 1 mass %. However, when the low molecular weight component is less than 1% by mass, migration of iodine from the iodine-containing polarizer cannot be suppressed, and the iodine concentration in the adhesive layer in contact with the metal layer laminated on the optical laminate increases. The inventors of the present invention obtained the knowledge that the iodine concentration in the adhesive layer can be suppressed by providing a layer containing a low-molecular component capable of trapping iodine between the iodine-containing polarizer and the adhesive layer in contact with the metal layer. rise. It is considered that this is because iodine is captured by low molecular components.

As for low-molecular components capable of trapping iodine, for example: molecules with epoxy groups, molecules with oxetane rings, molecules with acryloxyl groups, molecules with methacryloxyl groups; molecules with amine groups , amide group, acetyl group, urethane skeleton, isocyanate skeleton, acrylate group, methacryl group, urea group, etc. molecules; with urethane skeleton, urethane acrylate skeleton, pyridine skeleton, Molecules with piperidine skeleton, pyrrolidine skeleton, acridine skeleton, acridone skeleton, etc.; molecules with cationic substituents; polar molecules; cyclodextrin, [n]-CPP and other cyclic molecules; silver, copper, zinc and other metal ions; porous materials such as activated carbon and zeolite.

In the present invention, attention is focused on the adhesive layer as a layer containing a low-molecular component capable of trapping iodine. The adhesive layer is preferably a hardened layer of an active energy ray curable adhesive. The low-molecular components contained in the adhesive layer may contain unpolymerized monomers of active energy ray-curable adhesives, polymerization initiators, decomposition products of polymerization initiators, and other additives. The low molecular components contained in the adhesive layer can trap iodine. easy to control From the viewpoint of the compatibility of the adhesive and the suppression of exudation in a high-humidity environment, the low-molecular component that can capture iodine is preferably an unpolymerized monomer of the adhesive. The unpolymerized monomer contained in the adhesive preferably comprises a monomer selected from monomers having an epoxy group, monomers having an oxetane ring, monomers having an acryloxy group, and monomers having a methacryloxy group. At least one member of the group consisting of monomers of the base. The content of the unpolymerized monomer in the adhesive layer can be changed, for example, by adjusting the hardening degree of the adhesive. In the optical laminate, layers other than the adhesive layer, for example, a polymerizable liquid crystal retardation layer, may contain a low molecular weight component.

The adhesive layer contained in the optical function layer contains low molecular weight components with a molecular weight of 500 or less at 1 mass % or more and 10 mass % or less, and may be at least 3 mass % or 8 mass % or less. The higher the content of low-molecular components, the better the capture effect of iodine, so it is better. On the other hand, when the content of low-molecular components is too high, there is a fear that the effect of inhibiting iodine migration may decrease. In addition, when the content of low-molecular components is too high, the optical function of the polarizing plate may be deteriorated. When the optical function layer includes a plurality of adhesive layers, the aforementioned range is the ratio of the total mass of the low-molecular components contained in the plurality of adhesive layers to the total mass of the plurality of adhesive layers.

The ratio (mass %) of the low-molecular component contained in the adhesive layer can be calculated from (mass W2 of the low-molecular component contained in the adhesive layer)/(mass W1 of the adhesive layer). The mass W2 of the low molecular weight component contained in the adhesive layer was obtained as follows. First, the entire plurality of layers bonded by the adhesive layer is frozen and pulverized, and the obtained powder is extracted in a solvent. By analyzing this with a gas chromatograph, the amount of low-molecular components with a molecular weight of 500 or less can be determined. By using a gas chromatograph connected to a mass spectrometer (MS), functional groups of low-molecular components can also be identified. Through mass spectrometry analysis, the low-molecular components can be identified as those originating from the adhesive layer, and the mass W2 of the low-molecular components contained in the adhesive layer can be calculated. The multiple layers bonded by the adhesive layer can be the entire optical function layer, or a laminate including a polarizer, the first retardation layer, the adhesive layer and the second retardation layer, but it is preferred to remove for attaching to metal The adhesive layer of the layer is analyzed. The mass W1 of the adhesive layer can be calculated by (mass of the entire laminate for gas chromatography)×{(thickness of the adhesive layer)/(thickness of the entire laminate for gas chromatography)} .

For example, using a laminate in which the first retardation layer and the second retardation layer are bonded together via an adhesive layer, the content of the low molecular weight component in the adhesive layer is calculated as follows. Firstly, the laminated body is frozen and pulverized, extracted in a solvent and filtered to obtain a test solution for analysis by a gas chromatograph. Gas chromatography was performed to quantify the content of low-molecular components from the peak area of low-molecular components. The content of low-molecular components can be calculated from the following formula.

{Ratio of low-molecular components contained in the adhesive layer (mass%)}=[Content of low-molecular components originating from the adhesive layer in the test solution (mg/mL)×Amount of test solution (mL)]/[Layer Mass of body (mg)×{thickness of deposit agent layer ( μ m)/thickness of laminate ( μ m)}]×100

The optical lamination system can form a circular polarizer (including an elliptical polarizer). The optical laminate system can be used as an anti-reflection film for image display devices. Examples of image display devices include organic electroluminescence (organic EL) display devices, inorganic electroluminescence (inorganic EL) display devices, liquid crystal display devices, and electroluminescence display devices. The display device can be a flexible display.

Optical laminates can be used in display devices such as smartphones and tablet computers, and are especially suitable for touch panel display devices. In FIGS. 1 to 4 , the metal layer 40 may be a metal wiring layer constituting a sensor of a touch panel.

Hereinafter, each member which comprises an optical laminated body is demonstrated.

[polarizer]

The polarizing plate includes polarizers. The polarizer can have a protective film on one or both sides of the polarizer. The polarizing plate may further include a base film, an alignment film, and the like. When there is a protective film on one side of the polarizer, the protective film can be laminated on the opposite side of the polarizer to the optical function layer. When the polarizer is directly laminated on the light through the adhesive layer When the optical function layer is added, iodine easily migrates from the polarizer to the optical function layer. Even in the optical layered body having such a constitution, when the optical function layer contains an adhesive layer containing a large amount of low-molecular components, migration of iodine can be suppressed.

The luminescence factor corrected total light transmittance Ty of the polarizing plate is preferably at least 43.5%, more preferably at least 44.5%, and may be at least 45.5%. When the total light transmittance Ty is 43.5% or more, the iodine content of the polarizing plate tends to be low. Luminescence factor-corrected total light transmittance Ty can be measured with a spectrophotometer (V-7100 manufactured by JASCO Corporation).

(polarizer)

Polarizers have the property of transmitting linearly polarized light having a vibration plane perpendicular to the absorption axis when non-polarized light is incident on it. The polarizer is a polyvinyl alcohol-based resin film that absorbs and aligns iodine.

Polarizers can be used in polyvinyl alcohol-based resin films such as polyvinyl alcohol films, partially formaldehydeized polyvinyl alcohol films, and ethylene/vinyl acetate copolymer-based partially saponified films (hereinafter also referred to as "PVA-based films"), etc. Embryo membranes obtained by performing film-forming treatments such as iodine staining and stretching. If necessary, a boric acid aqueous solution can be used to treat the dyed PVA film with iodine adsorbed and oriented, and then, a cleaning step of washing away the boric acid aqueous solution can be performed. Known methods can be used in each step. The film thickness of the polyvinyl alcohol-based resin embryo film is, for example, from 10 μm to 100 μm , preferably from 10 μm to 60 μm , and may be from 15 μm to 30 μm .

Polyvinyl alcohol-based resin (hereinafter also referred to as "PVA-based resin") is obtained by saponifying polyvinyl acetate-based resin. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and other monomers that can be copolymerized with the vinyl acetate, in addition to polyvinyl acetate that is a homopolymer of vinyl acetate. Other monomers that can be copolymerized with vinyl acetate include, for example, unsaturated carboxylic acid-based compounds, olefin-based compounds, vinyl ether-based compounds, unsaturated phenyl-based compounds, and (meth)acrylamides with ammonium groups. Department of compounds.

The degree of saponification of the PVA-based resin is generally not less than 85 mol % and not more than 100 mol %, preferably not less than 98 mol %. PVA-based resins can be modified, and polyvinyl formaldehyde and polyvinyl acetal modified with aldehydes can also be used. The average degree of polymerization of the polyvinyl alcohol-based resin is generally not less than 1,000 and not more than 10,000, preferably not less than 1,500 and not more than 5,000. The average degree of polymerization of polyvinyl alcohol-based resins can be determined in accordance with JIS K 6726 (1994). When the average degree of polymerization is less than 1,000, it is difficult to obtain good polarizing performance, and when it exceeds 10,000, processability may be poor.

Other manufacturing methods of polarizers comprising PVA-based films may include the following steps: First, prepare a base film, coat a resin solution such as a PVA-based resin on the base film, perform drying to remove the solvent, etc., and coat the base film form a resin layer. As the base film, a resin film such as PET or a film using a thermoplastic resin that can be used as a protective film described later can be used. A primer layer may be formed in advance on the surface of the base film on which the resin layer is to be formed. As for the material of the primer layer, for example, a resin obtained by cross-linking a hydrophilic resin used in a polarizer, etc. may be mentioned.

Next, the amount of solvent such as moisture in the resin layer is adjusted as necessary, and then the base film and the resin layer are uniaxially stretched. Next, the resin layer was stained with iodine to allow iodine to be adsorbed and oriented on the resin layer. If necessary, the resin layer on which iodine is adsorbed orientated is treated with an aqueous solution of boric acid, and a cleaning step of washing away the aqueous solution of boric acid is performed. In this way, a polarizer belonging to a resin layer having adsorbed and oriented iodine is produced. Conventional methods can be used in each step.

The amount of boric acid in the boric acid-containing aqueous solution for treating the PVA film or PVA resin layer with iodine adsorbed orientated is usually more than 2 parts by mass and less than 15 parts by mass per 100 parts by mass of water, preferably 5 parts by mass More than 12 parts by mass. The aqueous solution containing boric acid preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually not less than 0.1 parts by mass and not more than 15 parts by mass, preferably not less than 5 parts by mass and not more than 12 parts by mass, per 100 parts by mass of water. in boric acid water The immersion time in the solution is usually not less than 60 seconds and not more than 1200 seconds, preferably not less than 150 seconds and not more than 600 seconds, more preferably not less than 200 seconds and not more than 400 seconds. The temperature of the aqueous solution containing boric acid is generally above 50°C, preferably above 50°C and below 85°C, more preferably above 60°C and below 80°C.

The uniaxial stretching of the base film and the PVA-based resin layer may be performed before dyeing, during dyeing, or during boric acid treatment after dyeing, or may be separately uniaxially stretched in these multiple stages. The base film and the PVA-based resin layer system can be uniaxially stretched in the MD direction (the direction in which the film is conveyed). extend. In addition, the base film and the PVA-based resin layer can be uniaxially stretched in the TD direction (direction perpendicular to the transport direction of the film). In this case, a so-called tenter method can be used. Furthermore, the stretching of the base film and the PVA-based resin layer may be dry stretching in which the stretching is carried out in the air, or wet stretching in which the PVA-based resin layer is stretched in a state of being swollen in a solvent. In order to exhibit the performance of the polarizer, the elongation ratio is 4 times or more, preferably 5 times or more, and particularly preferably 5.5 times or more. The upper limit of the elongation ratio is not particularly limited, but it is preferably 8 times or less from the viewpoint of suppressing breakage and the like.

The polarizer manufactured by the manufacturing method using a base film can be used as a linear polarizer after peeling off a base film, or can be used as a linear polarizer together with a base film. After laminating the protective film on the polarizer, the base film can be peeled off. According to this method, the polarizer can be thinned.

The thickness of the polarizer is preferably more than 1 μm , and may be more than 2 μm or more than 5 μm . The thickness of the polarizer is preferably less than 30 μm , and may be less than 15 μm , less than 10 μm or less than 8 μm . The smaller the thickness of the polarizer, the easier it is for iodine to seep out in a high-temperature and high-humidity environment.

(protective film)

As the protective film, it is preferable to use a film formed of a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture resistance, isotropy, extensibility, and the like. Specific examples of thermoplastic resins include Such as: cellulose resin such as triacetyl cellulose; polyester resin such as polyethylene terephthalate and polyethylene naphthalate; polyether resin; polyresin; polycarbonate resin; nylon or aromatic Polyamide resins such as polyamides; polyimide resins; polyolefin resins such as polyethylene, polypropylene, and ethylene/propylene copolymers; cyclic polyolefin resins with ring systems and norbornene structures (also known as (norcamphene-based resins); (meth)acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins, and mixtures thereof. When there are protective films on both sides of the polarizer, the resin compositions of the two protective films can be the same or different. In addition, in this specification, "(meth)acryl" means either acryl or methacryl. "(meth)" in (meth)acrylate etc. has the same meaning.

The protective film may have retardation, and may also have anti-reflection and anti-glare properties. The protective film can form a hard coat layer on the thermoplastic resin film. The hard coat layer may be formed on one side or both sides of the thermoplastic resin film. By providing a hard coat layer, a protective film having improved hardness and scratch resistance can be produced.

The thickness of the protective film is preferably at least 3 μm , and may be at least 5 μm . The thickness of the protective film is preferably less than 50 μm , and may be less than 40 μm or less than 30 μm .

When there is a protective film on the optical function layer side of the polarizer, the moisture permeability of the protective film at a temperature of 40°C and a relative humidity of 90%RH is preferably above 350g/(m ² .24hr), and can be 500g/(m ² .24hr ), 750g/(m ² .24hr) or 1000g/(m ² .24hr). The moisture permeability of the protective film at a temperature of 40° C. and a relative humidity of 90% RH is, for example, 2500 g/(m ² .24 hr) or less. When the moisture permeability of the protective film is high, iodine tends to migrate from the polarizing plate to the optical function layer side. However, when the optical function layer includes an adhesive layer containing a large amount of low-molecular components, migration of iodine can be suppressed.

The protective film can be laminated on the polarizer via an adhesive layer or an adhesive layer. The protective film is preferably laminated on the polarizer with an adhesive layer formed by drying a water-based adhesive containing a polyvinyl alcohol-based resin.

Surface functional layers such as anti-reflective layer, anti-glare layer and hard coating can be further provided on one side of the polarizing plate. The surface functional layer is preferably provided so as to be in direct contact with the protective film. The surface functional layer is preferably provided on the side of the protective film opposite to the side of the polarizer.

[Optical functional layer]

The optical function layer includes at least one adhesive layer. The optical function layer may contain a protective layer, a liquid crystal hardened layer, a retardation layer, a bonding layer, and the like. The optical functional layer includes, for example, one or more retardation layers. The optical function layer system includes, for example, two retardation layers, a first retardation layer, and a second retardation layer, and the first retardation layer and the second retardation layer can be laminated via a bonding layer. The first retardation layer and the polarizing plate may be laminated via an adhesive layer. The bonding layers can each independently be an adhesive layer or an adhesive layer.

The optical functional layer includes a λ/4 layer as a first retardation layer and a second retardation layer, and may further contain at least any one of a λ/2 layer or a positive C layer. When the retardation layer includes a λ/2 layer, the λ/4 layer and the λ/2 layer may be laminated sequentially from the polarizer side, or the λ/2 layer and the λ/4 layer may be laminated sequentially. When the retardation layer includes a positive C layer, the λ/4 layer and the positive C layer may be laminated sequentially from the polarizing plate side, or the positive C layer and the λ/4 layer may be laminated sequentially.

The optical function layer may further include an adhesive layer laminated on the surface opposite to the polarizing plate. When the optical functional layer is laminated on the metal layer, the adhesive layer can be used as an adhesive layer.

(adhesive layer)

The adhesive layer system can be formed by hardening the curable component in the adhesive composition. In terms of the adhesive composition used to form the adhesive layer, adhesives other than pressure sensitive adhesives (adhesives) may be used, for example, water-based adhesives and active energy ray-curing adhesives.

Examples of the water-based adhesive system include adhesives obtained by dissolving or dispersing polyvinyl alcohol-based resins in water. There is no particular limitation on the drying method when the water-based adhesive is used, for example, a drying method using a hot air dryer or an infrared dryer can be used.

Examples of active energy ray-curable adhesives include solvent-free active energy ray-curable adhesives containing curable compounds that are cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. Adhesiveness between layers can be improved by using a solvent-free active energy ray-curable adhesive.

Since the active energy ray-curable adhesive exhibits good adhesiveness, it is preferable to contain either one or both of a cation polymerizable curable compound and a radical polymerizable curable compound. The active energy ray-curable adhesive may further contain a cationic polymerization initiator such as a photocationic polymerization initiator for causing the curing reaction of the aforementioned curable compound, or a radical polymerization initiator.

Examples of cationically polymerizable hardening compounds include alicyclic epoxy compounds having an epoxy group bonded to an alicyclic ring, polyfunctional aliphatic compounds having two or more epoxy groups and not containing an aromatic ring. Epoxy compounds, monofunctional epoxy groups with one epoxy group (excluding those contained in alicyclic epoxy compounds), polyfunctional aromatic rings with two or more epoxy groups and aromatic rings Epoxy compounds such as oxygen compounds; oxetane compounds having one or more oxetane rings in the molecule; combinations of these.

In terms of radically polymerizable curable compounds, for example, (meth)acrylic compounds (compounds having one or more (meth)acryloxy groups in the molecule), radically polymerizable Other vinyl compounds with double bonds, or combinations thereof.

Active energy ray-curing adhesives may contain sensitizers such as photosensitizers as needed. By using a sensitizer, the reactivity can be improved, and the mechanical strength and bonding strength of the adhesive layer can be further improved. Sensitive In terms of chemical agents, knowledgeable persons can be used appropriately. When the sensitizer is prepared, the amount of the sensitizer is preferably not less than 0.1 parts by mass and not more than 20 parts by mass relative to 100 parts by mass of the total amount of the active energy ray-curable adhesive.

Active energy ray hardening adhesives may contain ion scavengers, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, antistatic agents, modifiers, etc. Additives such as leveling agents and solvents.

When using an active energy ray-curable adhesive, active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays can be irradiated to harden the applied layer of the adhesive to form an adhesive layer. In terms of active energy lines, ultraviolet rays are preferred. In terms of light sources at this time, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halides can be used. lights etc.

The thickness of the adhesive layer is preferably at least 0.01 μm , more preferably at least 0.05 μm , and more preferably at least 0.1 μm . From the viewpoint of improving flexibility, the thickness of the adhesive layer is preferably 10 μm or less, more preferably 5 μm or less.

(adhesive layer)

The adhesive layer is formed using an adhesive composition. Adhesive composition is bonded by itself and the object to be adhered to exert adhesiveness, which is the so-called pressure-sensitive adhesive. As for the adhesive composition, conventionally known adhesives with excellent optical transparency can be used without any particular limitation. The adhesive layer can be formed of an adhesive composition using (meth)acrylic resin, rubber resin, urethane resin, ester resin, silicone resin, polyvinyl ether resin as the base polymer . Among them, an adhesive composition using a (meth)acrylic resin excellent in transparency, weather resistance, heat resistance, etc. as a base polymer is preferable. The adhesive composition may be an active energy ray curing type or a thermosetting type. The adhesive layer is preferably made of (meth)acrylic It is composed of the reaction product of the adhesive composition of acid resin, crosslinking agent and silane compound, and may also contain other components.

As for the (meth)acrylic resin used in the adhesive composition, it is preferable to use butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, (meth) A polymer or copolymer of one or more (meth)acrylates such as 2-ethylhexyl acrylate as a monomer. A base polymer and a polar monomer are preferably copolymerized. Polar monomers include, for example, (meth)acrylic acid compounds, 2-hydroxypropyl (meth)acrylate compounds, hydroxyethyl (meth)acrylate compounds, (meth)acrylamide compounds, (meth) ) Acrylic acid-N,N-dimethylaminoethyl ester compound, (meth)acrylic acid glycidyl compound and other monomers having carboxyl, hydroxyl, amido, amino, epoxy groups, etc.

The adhesive composition may only include the aforementioned base polymer, and generally further includes a crosslinking agent. Examples of cross-linking agents include metal ions that are divalent or higher and form carboxylate metal salts with carboxyl groups, polyamine compounds that form amide bonds with carboxyl groups, and polyepoxides that form ester bonds with carboxyl groups. Compounds or polyols, and polyisocyanate compounds that form amide bonds with carboxyl groups. The crosslinking agent is preferably a polyisocyanate compound.

The active energy ray-curable adhesive composition has the property of being hardened by the irradiation of active energy rays such as ultraviolet rays or electron beams. The property of adhesive force is adjusted by irradiation hardening of active energy rays. The active energy ray-curable adhesive composition is preferably an ultraviolet-curable adhesive composition. The adhesive composition may further contain an active energy ray polymerizable compound in addition to the base polymer and the crosslinking agent. A photopolymerization initiator, a photosensitizer, etc. may be contained as needed.

Active energy ray polymerizable compounds include, for example: (meth)acrylate monomers having at least one (meth)acryloxy group in the molecule; reacting two or more functional group-containing compounds A (meth)acrylic compound such as a (meth)acryloxyl group-containing compound such as a (meth)acrylate oligomer having at least two (meth)acryloxyl groups in the molecule obtained. The adhesive composition may contain not less than 0.1 parts by mass of the active energy ray polymerizable compound, and may contain not more than 10 parts by mass, not more than 5 parts by mass, or not more than 2 parts by mass relative to 100 parts by mass of solids of the adhesive composition.

As a photoinitiator, a diphenyl ketone, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, etc. are mentioned, for example. A photopolymerization initiator may contain 1 type or 2 or more types. When the adhesive composition contains a photopolymerization initiator, the total content of the photopolymerization initiator may be not less than 0.01 parts by mass and not more than 3 parts by mass relative to 100 parts by mass of solids in the adhesive composition.

The adhesive composition may contain particles, beads (resin beads, glass beads, etc.), glass fibers, resins other than base polymers, tackifiers, fillers (metal powders or other inorganic powders) to impart light scattering properties. etc.), antioxidants, UV absorbers, dyes, pigments, colorants, defoamers, corrosion inhibitors, photopolymerization initiators and other additives.

The adhesive layer can be formed by applying the above-mentioned organic solvent dilution of the adhesive composition on the substrate and drying it. The adhesive layer can also be formed using an adhesive sheet formed of an adhesive composition. When an active energy ray-curable adhesive composition is used, an adhesive layer having a desired degree of hardening can be produced by irradiating the formed adhesive layer with active energy rays.

The thickness of the adhesive layer is not particularly limited, for example, it is preferably 1 μm to 100 μm , more preferably 3 μm to 50 μm , and may be 20 μm or more.

(retardation layer)

The retardation layer is a cured product containing a polymerizable liquid crystal compound. The retardation layer system may include an alignment layer having an alignment restricting force for aligning the polymerizable liquid crystal compound in a desired direction. The retardation layer may include an overcoat layer protecting its surface, a substrate layer supporting the retardation layer, and the like.

The polymerizable liquid crystal compound includes, for example, a rod-shaped polymerizable liquid crystal compound and a discotic polymerizable liquid crystal compound, either of which may be used, or a mixture containing both of them may be used. When the rod-shaped polymerizable liquid crystal compound is aligned horizontally or vertically relative to the substrate layer, the optical axis of the polymerizable liquid crystal compound is consistent with the long axis direction of the polymerizable liquid crystal compound. When the discotic polymerizable liquid crystal compound is oriented, the optical axis of the polymerizable liquid crystal compound exists in a direction perpendicular to the disc surface of the polymerizable liquid crystal compound. As the rod-like polymerizable liquid crystal compound, it is preferable to use, for example, those described in JP-A-11-513019 (Claim 1). In terms of discotic polymerizable liquid crystal compounds, it is preferable to use for example: Japanese Patent Application Laid-Open No. 2007-108732 (paragraph [0020] to [0067], etc.), Japanese Patent Application Publication No. 2010-244038 (paragraph [0013] to [ 0108] etc.)

The polymerizable liquid crystal compound may be oriented in an appropriate direction in order to express an in-plane retardation in the cured product layer formed by polymerizing the polymerizable liquid crystal compound. When the polymerizable liquid crystal compound is rod-shaped, an in-plane retardation is manifested by orienting the optical axis of the polymerizable liquid crystal compound horizontally with respect to the plane of the substrate layer. In this case, the direction of the optical axis coincides with the direction of the slow axis. When the polymerizable liquid crystal compound is discoid, the in-plane phase difference is generated by orienting the optical axis of the polymerizable liquid crystal compound horizontally with respect to the plane of the substrate layer. In this case, the optical axis and the slow The axes are orthogonal. The alignment state of the polymerizable liquid crystal compound can be adjusted through the combination of the alignment layer and the polymerizable liquid crystal compound.

The polymerizable liquid crystal compound is a compound having at least one polymerizable group and liquid crystallinity. When two or more polymerizable liquid crystal compounds are used in combination, at least one of them preferably has two or more polymerizable groups in the molecule. The polymerizable group refers to a group participating in a polymerization reaction, preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in a polymerization reaction by an active radical or an acid generated by a photopolymerization initiator described later. Examples of polymerizable groups include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, and oxycyclobutyl. , Oxirane, Styryl, allyl, etc. Among them, acryloxy, methacryloxy, vinyloxy, oxiranyl and oxetyloxy are preferred, and acryloxy is more preferred. The liquid crystal property of the polymerizable liquid crystal compound can be thermotropic liquid crystal or lyotropic liquid crystal, and when thermotropic liquid crystal is classified according to the degree of order, it can be nematic liquid crystal or smectic liquid crystal.

The thickness of the retardation layer may be 0.1 μm or more, 0.5 μm or more, 1 μm or more, 2 μm or more, and preferably 10 μm or less. It may be 8 μm or less, 5 μm or less.

The cured product layer of the polymerizable liquid crystal compound can be formed by applying a composition for forming a liquid crystal layer containing a polymerizable liquid crystal compound on a substrate layer, drying and polymerizing the polymerizable liquid crystal compound. The liquid crystal layer forming composition system can be coated on the alignment layer formed on the base material layer.

The alignment layer can be a vertical alignment layer in which the molecular axis of the polymerizable liquid crystal compound is vertically aligned relative to the substrate layer, can be a horizontal alignment layer in which the molecular axis of the polymerizable liquid crystal compound is horizontally aligned relative to the substrate layer, or can be a polymeric liquid crystal compound. An oblique orientation layer in which the molecular axis of the liquid crystal compound is obliquely oriented relative to the substrate layer.

As for the alignment layer, it is preferable to have solvent resistance that does not dissolve due to the application of the composition for forming a liquid crystal layer containing a polymerizable liquid crystal compound, and to have heat resistance to heat treatment for removing the solvent and aligning the polymerizable liquid crystal compound. . As for the alignment layer, for example: an alignment polymer layer formed by an alignment polymer, a photo-alignment polymer layer formed by a photo-alignment polymer, and a concave-convex pattern or a plurality of grooves ( groove) groove alignment layer.

As the base material layer, a film formed of a resin material can be used, for example, a film using a resin material as described in the case of using the thermoplastic resin used to form the aforementioned protective film can be used. The thickness of the substrate layer is not particularly limited, but generally from the standpoint of workability such as strength and operability, it is preferably from 1 μm to 300 μm , more preferably from 20 μm to 200 μm , and even more preferably It is not less than 30 μm and not more than 120 μm . The substrate layer can be combined with the cured layer of the polymerizable liquid crystal compound into the optical laminate, or the substrate layer can be peeled off, and only the cured layer of the polymerizable liquid crystal compound can be incorporated into the optical laminate, or the cured layer can be And the alignment layer is assembled into the optical laminated body. When the substrate layer and the cured layer of the polymerizable liquid crystal compound are combined into an optical laminate, the thickness of the substrate layer may be less than 30 μm , for example, 25 μm or less.

[metal layer]

The metal layer can be used as a conductive layer for forming a touch sensor of a touch panel. The metal layer is a layer formed of one or more metals. The metal layer system can form a passivation film (oxide film) on its surface. The metal layer can be a single-layer structure or a multi-layer structure. Also, the passivation film is not considered as 1 layer.

As for the metal constituting the metal layer, for example: aluminum (Al), copper (Cu), gold (Au), silver (Ag), titanium (Ti), palladium (Pd), chromium (Cr), nickel (Ni) , tungsten (W), platinum (Pt), iron (Fe), indium (In), tin (Sn), iridium (Ir), rhodium (Rh), neodymium (Nd), molybdenum (Mo), or both Alloys of the above metals. Among them, the metal layer is preferably one whose main component is aluminum or copper, and may contain titanium as an additive. Here, the main component refers to a metal accounting for 50% by mass or more of the metals constituting the metal layer.

The metal layer may be formed on, for example, a translucent substrate, may be a continuous film formed on the entire surface of the translucent substrate, or may be a metal wiring layer formed on the surface of the translucent substrate. The metal wiring layer may be a metal mesh. The light-transmitting base material should just be what has light-transmitting property, For example, the film which used the resin material demonstrated as the said thermoplastic resin, a glass film, a glass substrate, etc. are mentioned.

The method for forming the metal layer is not particularly limited, and can be formed on the surface of the transparent substrate by, for example, the aforementioned chemical vapor deposition method, physical vapor deposition method, inkjet printing method, gravure printing method, electroplating, electroless plating (chemical Plating) and so on.

The thickness of the metal layer is generally 0.01 μm or more, may be 0.05 μm or more, and, from the viewpoint of thinning, is preferably 3 μm or less, more preferably 1 μm or less, and more preferably 0.8 μm the following.

When the metal layer is a metal wiring layer, its line width is generally less than 10 μm , may be less than 5 μm , or less than 3 μm , and generally more than 0.5 μm .

<Manufacturing method of optical laminate>

One mode of the manufacturing method of the optical laminate includes the step of laminating the layer with an active energy ray-curable adhesive, for example, including: bonding the first retardation layer of the cured layer containing the polymerizable liquid crystal compound to the layer of the polymerizable liquid crystal compound. The second retardation layer of the hardened layer is bonded with an active energy ray-curable adhesive, or the first retardation layer of the hardened layer containing a polymerizable liquid crystal compound and the polarizing plate are bonded with an active energy ray-curable adhesive The step of bonding. In this step, the degree of curing of the adhesive is adjusted so that the active energy ray-curable adhesive is not completely cured and unpolymerized monomers remain in the adhesive layer. The degree of hardening of the adhesive can be adjusted by controlling the irradiation amount of active energy rays, the amount of transmission of active energy rays, and the like.

For example, the amount of active energy ray irradiation for curing the adhesive can be reduced to such an extent that the adhesive cannot be completely cured. The irradiation dose of active energy rays (UVB) may be less than 90% or less than 80% of the irradiation dose when the adhesive is completely hardened. The amount of active energy ray irradiation may be, for example, 550 mJ/cm ² or less, 450 mJ/cm ² or less, 400 mJ/cm ² or less, 350 mJ/cm ² or less, or 300 mJ/cm ² or less. The irradiation dose of active energy rays is generally above 200mJ/cm ² .

The transmittance of active energy rays (UVB) can be adjusted, for example, by adding an ultraviolet absorber. The ultraviolet absorber may be contained in any layer from the adhesive layer to the surface layer on the active energy ray irradiation side, and may be contained in the base material layer or the adhesive layer. The ultraviolet absorber is not particularly limited, and examples thereof include oxybenzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, cyanide Organic ultraviolet absorbers such as acrylate-based ultraviolet absorbers and triazine-based ultraviolet absorbers; titanium oxide, zinc oxide, indium oxide, tin oxide, talc, high Inorganic ultraviolet absorbers such as clay, calcium carbonate, titanium oxide-based composite oxides, zinc oxide-based composite oxides, ITO (indium tin oxide), ATO (antimony tin oxide), etc.

[Example]

The following examples are presented to illustrate the present invention in more detail, but the present invention is not limited to these examples.

[Calculation of Ratio of Low Molecular Components]

Using a laminate having the composition of first substrate layer/first retardation layer/adhesive layer (ultraviolet curable adhesive layer)/second retardation layer/second substrate layer, calculate the The ratio of low molecular components contained. First, the first base material layer and the second base material layer are peeled and removed from the laminate. The laminate of the first retardation layer/adhesive layer/second retardation layer was frozen and pulverized, dissolved in a solvent (acetonitrile) and filtered to obtain a test solution.

The obtained test solution was subjected to gas chromatography, and low-molecular components were quantified from the peak areas of components with a molecular weight of 500 or less. According to mass analysis, about 40% of the components with a molecular weight below 500 are unpolymerized monomers (monomers with epoxy groups) that are UV-curable adhesives. The measurement conditions are as follows.

Device: Agilent 6850 GC (Agilent Technologies Inc.)

Carrier Gas: Helium

Flow rate: 1.0mL/min. (constant flow)

Column: DB-5 0.25mmΦ×30m, 0.25μm (Agilent Technologies Co., Ltd.)

Oven: 50°C (5 minutes hold) -10°C/min.-320°C (8 minutes hold)

Injection volume: 1.0 μL

Injection port temperature: 250°C

Injection mode: splitless (purge flow of split vent: 50mL/min., 1min. Gas saver: 15mL/min., 2min.)

Detection: FID (250°C, hydrogen: 40mL/min., air: 400mL/min., auxiliary gas: helium 45mL/min.)

The ratio of the low-molecular component was calculated according to the following formula.

{Content of low-molecular components in the adhesive (%)}=(Content of low-molecular components derived from the adhesive layer in the test solution (mg/mL))÷{Amount of powder when the test solution was prepared (mg) }×{Amount of solvent used in preparation of test solution (mL)}÷{Film thickness of adhesive layer ( μm )}×{The whole laminate after peeling and removing the first base material layer and the second base material layer Thickness ( μ m)}×100

[Determination of the amount of iodine contained in the adhesive layer]

Cut the optical laminate body into a size of 25mm×50mm, peel off the protective film, and use an adhesive to bond the polarizer side to the alkali-free glass. The optical laminate was stored in an oven at a temperature of 85° C. and a relative humidity of 85% RH for 240 hours. Peel off the release film on the side of the second retardation layer, and scrape off the adhesive of the adhesive layer. The amount of iodine [ppm] contained in the scraped adhesive was measured by oxidation combustion ion chromatography performed under the following conditions.

<Sample burning>

Device: AQF-2100H manufactured by Mitsubishi Chemical Analytical Technology Co., Ltd.

Combustion conditions: the combustion temperature is 1100°C, the gas flow rate is 200mL/min for argon, 400mL/min for oxygen, and 100mL/min for humidified air.

<Ion Chromatograph>

Device: Integrion manufactured by Thermo Fisher Scientific

Column: IonPac AS19 manufactured by Thermo Fisher Scientific

Determination conditions: the eluent is a KOH aqueous solution gradient, the flow rate is 1.0mL/min, the injection volume is 100 μL , the measurement mode is suppressor type, and the detector is a conductivity detector.

[Determination of storage modulus]

Adhesive layers were stacked to a thickness of 150 μm and bonded to glass plates. For this storage modulus measurement sample, the storage modulus was measured using a rheometer ("MCR-301" manufactured by Antonio Parr) under the conditions of a temperature of 25° C., a relative humidity of 50%, a stress of 1%, and a frequency of 1 Hz.

[Measurement of thickness]

The thickness was measured using a contact film thickness measuring device (“MS-5C” manufactured by Nikon Corporation). The thicknesses of the adhesive layer, the polarizer layer, and the alignment film were measured using a laser microscope (“OLS3000” manufactured by Olympus Co., Ltd.).

[Determination of Luminescence Factor Corrected Total Light Transmittance Ty and Luminescence Factor Corrected Polarization Py]

The total light transmittance Ty and polarization Py from a wavelength of 380 nm to a wavelength of 780 nm were measured using a spectrophotometer with an integrating sphere ["V7100" manufactured by JASCO Co., Ltd., 2-degree viewing angle; C light source] for measurement.

[Determination of moisture permeability]

Using a constant temperature and humidity chamber, under the measurement conditions of temperature 40°C, relative humidity 90%RH, and measurement time 24 hours, the water vapor transmission rate was measured according to the moisture permeability test method (moisture permeability cup method, in accordance with JIS Z 0208). The measured water vapor transmission rate is used as the water vapor transmission rate at a temperature of 40°C and a relative humidity of 90%RH.

[Making of polarizing plate]

A polyvinyl alcohol-based resin film with a thickness of 30 μm (the average degree of polymerization is about 2400, and the degree of saponification is more than 99.9 mole%) is stretched longitudinally and uniaxially about 5 times through dry stretching, and kept under tension at a temperature of 60°C. After immersion in pure water for 1 minute, it was immersed for 60 seconds in an aqueous solution at a temperature of 28° C. at a mass ratio of iodine/potassium iodide/water of 0.05/5/100. Then, it immersed in the aqueous solution of temperature 72 degreeC whose mass ratio of potassium iodide/boric acid/water was 8.5/8.5/100. Next, after washing in pure water at a temperature of 26°C for 20 seconds, drying treatment was performed at a temperature of 65°C. A polarizer having a thickness of 12 μm in which iodine was adsorbed and oriented on the polyvinyl alcohol-based resin film was obtained.

3 parts by mass of carboxy-modified polyvinyl alcohol ["KL-318" manufactured by Kuraray Co., Ltd.] was dissolved in 100 parts by mass of water to prepare an aqueous polyvinyl alcohol solution. To the obtained aqueous solution, a water-soluble polyamide epoxy resin ["Sumirez® Resin 650 (30)" manufactured by Tianoka Chemical Industry Co., Ltd. was added at a ratio of 1.5 parts by mass with respect to 100 parts by mass of water, solid concentration of 30% by mass] and mixed to obtain a water-based adhesive.

A water-based adhesive is applied to one side of the polarizer, and a triacetyl cellulose film (hereinafter also referred to as "TAC film") having a hard coat layer (hereinafter also referred to as "HC layer") is laminated. Apply the aforementioned water-based adhesive to the other side to laminate the TAC film. By drying at a temperature of 80° C. for 5 minutes, a polarizing plate 1 having protective films on both sides of the polarizing plate was obtained. The moisture permeability of TAC film with HC layer is 450g/(m ² ‧24hr), and the moisture permeability of TAC film is 1200g/(m ² ‧24hr). A protective film with an adhesive layer on the base film is laminated on the HC layer of the polarizing plate to obtain a polarizing plate with protective film (hereinafter also referred to as "polarizing plate with PF").

In the manufacturing process of the polarizer, the concentration of the iodine-containing aqueous solution and the immersion time in the aqueous solution were adjusted to obtain polarizers 2 to 4 with different optical properties. Polarizers 3 and 4 used TAC films as protective films on both surfaces. Table 1 shows the total light transmittance Ty and polarization degree Py measured using a polarizing plate with protective films on both sides of the polarizing plate.

[Table 1]

An acrylic adhesive layer (storage modulus: 125,000 Pa) with a thickness of 5 μm and a release film attached to both sides was prepared. The peeled surface of one of the above-mentioned adhesive layers with a release film was bonded to the opposite side of the PF (TAC film side) of the polarizing plate with PF. Subsequently, the other release film of the adhesive layer was peeled off to obtain a polarizing plate with an adhesive layer. The polarizing plate with the adhesive layer has protective film/polarizing plate (protective film/polarizer/protective film)/adhesive layer in sequence.

[Production of retardation layer]

(first retardation layer)

A rod-shaped composition for forming a liquid crystal layer containing a nematic polymerizable liquid crystal compound is coated on a base layer formed of a transparent resin to prepare a first retardation layer with a first base layer. The first retardation layer has a 1/4 wavelength retardation characteristic (the retardation value at a wavelength of 550nm is 142nm). The thickness of the first retardation layer is 1 μm .

(second retardation layer)

The second retardation layer with the second substrate layer was fabricated by the following method. First, 10.0 parts by mass of polyethylene glycol di(meth)acrylate, 10.0 parts by mass of trimethylolpropane triacrylate, 10.0 parts by mass of 1,6-hexanediol di(meth)acrylate, and Irgacure 907 1.50 parts by mass of photopolymerization initiator It was dissolved in 70 parts by mass of methyl ethyl ketone as a solvent to prepare a composition for forming an alignment layer. Next, 20 parts by mass of a photopolymerizable nematic liquid crystal compound and 1.0 parts by mass of Irgacure 907 as a photopolymerization initiator were dissolved in 80.0 parts by mass of propylene glycol monomethyl ether acetate as a solvent to prepare a liquid crystal layer forming Composition.

Corona treatment was performed on one side of the substrate layer, and the prepared composition for forming an alignment layer was coated on the corona-treated side with a bar coater. The coating layer was heat-treated at 80° C. for 60 seconds, and then irradiated with ultraviolet rays to polymerize and harden the alignment layer-forming composition to form an alignment layer with a thickness of 1.8 μm on the substrate layer. The composition for forming a liquid crystal layer prepared above was coated on the alignment layer. The coating layer was heat-treated at 80° C. for 60 seconds, and then irradiated with ultraviolet rays to polymerize and harden the liquid crystal layer forming composition to form a 0.7 μm thick liquid crystal cured layer on the alignment layer. Thus, the second retardation layer with the second base material layer was obtained. The retardation value Rth of the second retardation layer was -75 nm.

(ultraviolet curable adhesive)

Mix the cation-curable components shown below to prepare a UV-curable adhesive.

3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name: CEL2021P, manufactured by Daicel Co., Ltd.): 70 parts by mass

Neopentyl glycol diglycidyl ether (trade name: EX-211, manufactured by Nagase ChemteX Co., Ltd.): 20 parts by mass

2-Ethylhexyl glycidyl ether (trade name: EX-121, manufactured by Nagase ChemteX Co., Ltd.): 10 parts by mass

Cationic polymerization initiator (trade name: CPI-100_50% solution, manufactured by San-Apro Co., Ltd.): 4.5 parts by mass (substantial solids 2.25 parts by mass)

1,4-diethoxynaphthalene: 2.0 parts by mass

(lamination of retardation layer)

Corona treatment was performed on the retardation layer side of the first retardation layer with the first substrate layer and the retardation layer side of the second retardation layer with the second substrate layer respectively. Coating the modulated ultraviolet curable adhesive on one of the corona-treated surfaces, bonding the first retardation layer with the first substrate layer and the second substrate layer with the second substrate layer. Ultraviolet rays are irradiated from the second base material layer side to cure the ultraviolet curable adhesive to form an adhesive layer. The ultraviolet system irradiates UVB with a wavelength of 315nm to 280nm at 420mJ/cm ² . The maximum transmittance in the UVB region of the second substrate layer is 36%. A laminated body 1 of the first substrate layer/first retardation layer (liquid crystal cured layer)/adhesive layer/second retardation layer (liquid crystal cured layer/alignment layer)/second substrate layer was obtained. The thickness of the cured ultraviolet curable adhesive layer was 1.5 μm .

The same as laminated body 1 except adding UV absorber to the second substrate layer to reduce the UVB transmittance to 12%, and changing the UVB irradiation amount between 510mJ/cm ² and 210mJ/cm ² Method Laminates 2 to 6 were produced. Table 2 shows the calculation results of the ratio of low molecular weight components contained in the adhesive layer for laminates 1 to 6. The lower the UVB transmittance, the lower the UVB exposure, and the higher the ratio of low-molecular components.

[Table 2]

As shown in Tables 3 to 6, laminates 1 to 6 and polarizing plates 1 to 4 with adhesive layers were combined and laminated to produce optical laminates. At this time, the 1st base material layer is peeled from a laminated body, and the 1st retardation layer and the adhesive layer of the polarizing plate with an adhesive layer are laminated|stacked. Furthermore, one of the release films of the adhesive layer (storage modulus: 25500 Pa) with a thickness of 15 μm attached to both sides of the release film was peeled off, and the second base material was laminated on the second retardation layer after peeling. . In this way, an optical laminate in which protective film/polarizing plate/adhesive layer/first retardation layer/adhesive layer/second retardation layer/adhesive layer/release film is laminated is obtained.

The release film on the side of the pellicle and the second retardation layer was peeled from the optical layered body. The optical laminate and the non-alkali glass were bonded through the adhesive layer on the side of the second retardation layer. This laminate was stored at a temperature of 60° C. and a relative humidity of 95% RH for 250 hours to perform a high humidity heat test. Measure the total light transmittance Ty and the degree of polarization Py before and after the high humidity heat test, and calculate the change rate of the degree of polarization (△Py)={(Py after the test)-(Py before the test)}.

The iodine concentration was also measured using an optical laminate. Peel off the protective film from the optical laminate and stick it to the non-alkali glass. This laminate was subjected to a high humidity heat test (temperature 85°C, relative humidity 85%RH). The iodine concentration after the high humidity heat test laminated in the adhesive layer of the second retardation layer was measured, and the reduction amount and reduction rate when compared with the optical laminated body laminated with the laminated body 1 were calculated. The amount of reduction was calculated as {(the iodine concentration contained in the adhesive layer of the optical layered body laminated with the layered body 1)-(the iodine concentration contained in the adhesive layer of each optical layered body)}. The decrease rate (%) is calculated by {(the concentration of iodine contained in the adhesive layer of the optical laminate laminated with laminate 1)-(the concentration of iodine contained in the adhesive layer of each optical laminate)}/(lamination The concentration of iodine contained in the adhesive layer of the optical layered body laminated in body 1) was calculated.

[table 3]

[Table 4]

[table 5]

[Table 6]

When the ratio of the low-molecular components contained in the adhesive layer is 1 to 10% by mass, the reduction rate of the iodine concentration in the adhesive layer is 25% or more, indicating that the migration of iodine from the polarizer to the adhesive layer is suppressed. When the ratio of low-molecular components contained in the adhesive layer is 3 to 8% by mass, the decrease rate of iodine concentration in the adhesive layer is more than 30%, and the migration of iodine from the polarizer to the adhesive layer is suppressed.

10: polarizer

11: Polarizer

12: Protective film

20:Optical functional layer

21: The first retardation layer

22: The second retardation layer

23,24: Bonding layer

30: Adhesive layer

40: metal layer

100: Optical laminate

Claims (8)

An optical laminate comprising: a polarizing plate containing a polarizing plate, and an optical functional layer containing at least one adhesive layer, wherein, The aforementioned polarizer is a polyvinyl alcohol-based resin film with iodine adsorbed and oriented. The said adhesive layer contains the low molecular weight component whose molecular weight is 500 or less in total at 1 mass % or more and 10 mass % or less. The optical laminated body according to claim 1, wherein, The aforementioned optical functional layer includes: a first retardation layer and a second retardation layer containing a cured product of a polymerizable liquid crystal compound, At least one layer of the adhesive layer is laminated between the first retardation layer and the second retardation layer. The optical laminate according to claim 1 or 2, wherein, The aforementioned adhesive layer is a hardened layer of an active energy ray curable adhesive, The aforementioned low-molecular-weight components include unpolymerized monomers of the aforementioned active energy ray-curable adhesive. The optical layered body according to any one of Claims 1 to 3, wherein the aforementioned low-molecular-weight components include monomers having an epoxy group, monomers having an oxetane ring, and monomers having an acryloxy group. At least one member of the group consisting of a monomer having a methacryloxy group and a monomer having a methacryloxy group. The optical laminate according to any one of claims 1 to 4, wherein the polarizing plate has a protective film on one or both sides of the polarizing plate. The optical laminate according to Claim 5, wherein the polarizing plate has the protective film on the side of the optical function layer of the polarizing plate, The moisture permeability of the aforementioned protective film at a temperature of 40°C and a relative humidity of 90%RH is above 350g/(m ² ‧24hr). The optical laminate according to any one of claims 1 to 6, wherein the luminescence factor corrected single transmittance Ty of the polarizing plate at a wavelength of 550 nm is 43.5% or more. The optical laminate according to any one of Claims 1 to 7, further comprising an adhesive layer laminated on the surface of the optical function layer opposite to the polarizing plate.

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