TWI796298B - Optical laminate - Google Patents

Abstract

The objective of the present invention is to provide an optical laminate which is hardly yellowed over time and is excellent in yellowing suppression effect when exposed to high temperature environment.

The optical laminate of the present invention comprises, in this order a first adhesive layer, a polarizing plate and a second adhesive layer, wherein the polarizing plate comprises a polarizer having a thickness of 23 μm or less, the polarizer is a polyvinyl alcohol-based resin film containing a dichroic dye, when the total thickness of all of the adhesive layers contained in the optical layered body is T1 and the thickness of the polarizer is T2, T2/T1 is 0.6 or less.

Description

Optical laminate

The present invention relates to an optical laminate and an image display device containing the optical laminate. More specifically, it relates to an optical layered body that is bonded and used between a transparent plate and an image display unit through an adhesive layer, and an image display device including the aforementioned optical layered body.

In the past, optical laminate systems such as polarizing plates or elliptical polarizing plates were bonded through an adhesive layer between image display units such as liquid crystal units or organic EL elements and transparent plates such as front panels or touch panels, and were used in liquid crystal display devices or organic devices. Various image display devices such as EL display devices. In recent years, such image display devices have been widely used as car image display devices such as car navigation devices and rear monitors, in addition to portable devices such as mobile phones and tablet terminals. Along with this, compared with conventional requirements, optical layering systems require high durability in harsher environments (such as high-temperature environments), and a polarizing plate for ensuring such durability has been proposed (Patent Document 1).

[Prior Art Literature] [Patent Document]

Patent Document 1: Japanese Patent Laid-Open No. 2014-102353.

An image display device constructed by laminating a polarizer using a polyvinyl alcohol-based resin film containing a dichroic dye between an image display unit and a transparent plate through an adhesive layer, will undergo thermal damage when exposed to a high temperature environment. The polyeneization of polyvinyl alcohol will cause the problem of yellowing of the optical laminate. Such yellowing becomes a defect in the appearance of the optical layered body, and as the yellowing progresses, defects in the optical properties of the optical layered body occur. In particular, under severe temperature conditions exceeding 95°C (for example, 105°C, etc.), yellowing tends to progress more significantly, and an optical laminate with a high inhibitory effect on yellowing in such a high-temperature environment is required.

Therefore, an object of the present invention is to provide an optical layered body which is less prone to yellowing over time and which is excellent in the effect of inhibiting yellowing when exposed to a high-temperature environment.

The inventors of the present invention have diligently examined to solve the above-mentioned problems, and as a result, completed the present invention.

That is, the present invention provides the following preferred aspects.

[1] An optical laminate comprising a first adhesive layer, a polarizing plate, and a second adhesive layer in this order; the polarizing plate includes a polarizer with a thickness of 23 μm or less, and the polarizer contains a dichroic pigment The polyvinyl alcohol-based resin film; the total thickness of all adhesive layers contained in the aforementioned optical laminate is T1. When the thickness of the aforementioned polarizer is T2, T2/T1 is 0.6 or less.

[2] The optical laminate as described in [1] above, wherein the absorbance A ₇₀₀ of the polarizer at a wavelength of 700 nm is 5.5 or less.

[3] The optical laminate as described in [1] or [2] above, which is used by bonding between the transparent plate and the image display unit through the adhesive layer.

[4] The optical laminate described in any one of [1] to [3] above, wherein the polarizing plate includes a protective film laminated on at least one side of the polarizing plate, and the protective film has a thickness of 200 g/m ² ． More than 24 hours of moisture permeability.

[5] An image display device comprising the optical laminate described in any one of [1] to [4].

According to the present invention, it is possible to provide an optical layered body which is less prone to yellowing over time and which is excellent in the effect of inhibiting yellowing when exposed to a high-temperature environment.

1‧‧‧Polarizer

2‧‧‧The first adhesive layer

2’‧‧‧Second Adhesive Layer

3‧‧‧Protective film

4‧‧‧adhesive layer

5‧‧‧Protection sheet

6‧‧‧Transparent board

7‧‧‧Image display unit

10‧‧‧polarizer

Fig. 1 is a cross-sectional view showing the structure of an optical laminate according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing the structure of an image display device according to an embodiment of the present invention.

Embodiments of the present invention will be described in detail below. In addition, the scope of the present invention is not limited to the embodiment described here, and various changes can be made within the scope not exceeding the gist of the present invention.

The optical layered body of one embodiment of the present invention (also referred to as "the optical layered body of the present invention") includes a first adhesive layer, a polarizing plate, and a second adhesive layer in this order. When illustrating the composition of an embodiment of the optical laminated body of the present invention according to Fig. 1, the optical laminated system of the present invention layers the first adhesive layer (2) on one area of the polarizing plate (10), and the polarizing plate ( 10) It is formed by layering the second adhesive layer (2') on the side opposite to the first adhesive layer (2). In the optical laminate of the present invention, in order to protect the adhesive layer, the first adhesive layer (2) and the second adhesive layer (2') can be respectively pasted and peeled on the surface opposite to the polarizing plate (10). The protective sheet (5).

The protective sheet (5) is peeled off, and the first adhesive layer (2) is attached to the image display unit (7) and the second adhesive layer (2') is attached to the transparent plate (6), thereby forming the following An image display device according to an embodiment of the present invention shown in FIG. 2 (also referred to as "the image display device of the present invention"). In addition, in Fig. 2 , the backlight and the like are omitted.

The polarizing plate (10) constituting the optical laminate of the present invention includes the polarizing plate (1). The polarizer (10) can have a structure with a protective film (3) on at least one side of the polarizer (1), and the polarizer (1) and the protective film (3) can also be bonded through the adhesive layer (4). In one embodiment of the optical layered body of the present invention, the optical layered system of the present invention has a protective film (3) on both sides of the polarizer (1) through the adhesive layer (4).

Each constituent member of the optical layered body of the present invention will be described in detail below.

<Optical laminate>

In the optical layered body of the present invention, all the adhesives constituting the optical layered body When the total thickness of the coating layer is T1 and the thickness of the polarizer is T2, the value of T2/T1 is 0.6 or less, preferably 0.55 or less, more preferably 0.50 or less, most preferably 0.45 or less. When the value of T2/T1 exceeds 0.6, it is difficult to suppress yellowing when exposed to a high temperature environment (especially at a temperature exceeding 95° C., for example, at a temperature above 105° C.). The lower limit of T2/T1 in the optical laminate of the present invention is not particularly limited, but is, for example, 0.001 or more, preferably 0.005 or more, more preferably 0.008 or more, and still more preferably 0.01 or more. Also, the total thickness T1 of all the adhesive layers constituting the optical laminate is the sum of the thicknesses of the first adhesive layer and the second adhesive layer, and the thicknesses of other adhesive layers as appropriate.

Other adhesive layers may be included in the optical laminate and are adhesive layers other than the first adhesive layer and the second adhesive layer, such as adhesives used to bond the optical film or optical layer described later to the polarizing plate layer, and an adhesive layer that can be used to bond polarizers and protective films, etc. When the optical laminate does not contain other adhesive layers, and the adhesive layer only contains the first adhesive layer and the second adhesive layer, the total thickness T1 of all the adhesive layers constituting the optical laminate is the thickness of the first adhesive layer and The total thickness of the second adhesive layer.

In the present invention, the thickness (T2) of the polarizer is 23 μm or less, preferably 20 μm or less, more preferably 18 μm or less, and more preferably 15 μm or less. When the thickness of the polarizer is not more than the above upper limit, it is difficult to cause yellowing of the optical layered body over time, and an excellent yellowing suppression effect can be obtained. Also, if the thickness of the polarizer is below the above upper limit and the thickness of the polarizer becomes smaller, the thickness of the required adhesive layer is also smaller, which is advantageous from the viewpoint of thinning the optical laminate. Moreover, although the lower limit of the thickness of the said polarizer is not specifically limited, For example, it is 3 micrometers or more.

In the present invention, controlling the ratio of the thickness of the polarizer to the total thickness of the adhesive layer within a specific range is one of the features for obtaining the effect of inhibiting yellowing. That is, for example, even if the thickness of the polarizer is the same, if the relationship with the total thickness of the adhesive layer does not satisfy the above-mentioned specific ratio, it is difficult to obtain a sufficient yellowing inhibitory effect. Similarly, even if the total thickness of the adhesive layer is the same, if the relationship with the thickness of the polarizer does not satisfy the above-mentioned specific ratio, it is difficult to sufficiently suppress yellowing when exposed to a high-temperature environment.

In the optical layered body of the present invention, by setting the ratio of the thickness of the polarizer and the thickness of the polarizer to the total thickness of the pressure-sensitive adhesive layer within the above-mentioned specific range, a high yellowing suppression effect can be easily provided to the optical layered body. The reason for the yellowing of the optical laminate is the polyeneization of the polyvinyl alcohol in the polarizer. When the moisture content of the polarizer is high, the polyeneization tends to be promoted. Therefore, for example, in order to suppress polyeneization, a method of controlling the moisture content of the polarizing plate can be used, but a drying step for controlling the moisture content of the polarizing plate is required, and the drying step is performed under high temperature and/or long-term drying conditions. When it is used, the optical characteristics of the polarizer will be reduced. In the present invention, yellowing can be suppressed by controlling the thickness of the polarizer and the ratio of the thickness of the polarizer to the total thickness of the adhesive layer within the aforementioned specific range, so that the drying step for adjusting the moisture content of the polarizer is not required, and It is not easy to reduce the optical characteristics of the polarizing plate. In addition, when a drying step is not required, it can be easily and efficiently produced, and productivity can be improved. Also, by controlling the thickness of the polarizer and the total thickness of the adhesive layer as described above, the yellowing inhibitory effect can be imparted, so there is no need to limit the constituent components and/or composition of the polarizer or protective film constituting the polarizing plate, and can be combined Polarizers and protective films of various configurations are used. Therefore, easy to obtain materials or cheap materials can be selected to It is also advantageous from the standpoint that production costs can be further reduced. Moreover, by designating the constituent components and/or composition of the polarizer which comprises a polarizing plate, a protective film, etc., a high yellowing suppression effect can be provided further.

<Polarizer>

In the present invention, the polarizing plate is composed of a polarizing plate. A polarizer is a film that has the function of extracting linearly polarized light from incident natural light, and it is a polyvinyl alcohol-based resin film containing a dichroic pigment. As the polyvinyl alcohol-based resin constituting the polyvinyl alcohol-based resin film, a saponified product of polyvinyl acetate-based resin can be used. In terms of polyvinyl acetate resins, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, copolymers of vinyl acetate and other monomers that can be copolymerized with it (such as ethylene/vinyl acetate copolymer, etc.) ). Other monomers that can be copolymerized with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides with ammonium groups.

The degree of saponification of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably more than 98 mol%. The polyvinyl alcohol resin can be modified, for example, polyvinyl formaldehyde, polyvinyl acetal, and polyvinyl butyral modified with aldehydes can be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000.

Those made of such a polyvinyl alcohol-based resin can be used as a raw material film for a polarizer. The film-forming method of the polyvinyl alcohol-based resin is not particularly limited, and a conventionally known method can be used to form a film. The film thickness of the raw film made of polyvinyl alcohol-based resin is not particularly limited, but considering the easiness of stretching, for example 10 to 150 μm, preferably 15 to 100 μm, more preferably 20 to 80 μm.

Polarizers are generally manufactured through the following steps: a step of uniaxially stretching such a polyvinyl alcohol-based resin film, a step of absorbing a dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye, A step of treating the polyvinyl alcohol-based resin film on which the dichroic dye is adsorbed with an aqueous solution of boric acid, and a step of washing with water after the treatment with the aqueous solution of boric acid. Moreover, a polyvinyl alcohol-type resin film contains a dichroic dye by dyeing a polyvinyl alcohol-type resin film with a dichroic dye. When a polarizer is produced by this production method, the polarizer is formed as a stretched polyvinyl alcohol-based resin film containing a dichroic dye.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing, or may be performed after dyeing. When performing uniaxial stretching after dyeing, this uniaxial stretching may be performed before boric-acid treatment, and may be performed during boric-acid treatment. Uniaxial stretching may be performed in these plural stages. In the case of uniaxial stretching, uniaxial stretching may be performed between rolls having different circumferential speeds, or uniaxial stretching may be performed using heated rolls. In addition, the uniaxial stretching may be dry stretching in which the film is stretched in the air, or wet stretching in which the polyvinyl alcohol-based resin film is stretched in a swollen state using a solvent. From the viewpoint of suppressing deformation of the polarizer, the draw ratio is preferably at most 8 times, more preferably at most 7.5 times, and even more preferably at most 7 times. Moreover, from a viewpoint of expressing the function as a polarizer, a draw ratio is 4.5 times or more normally. Time-dependent deformation of a polarizer can be suppressed by making a draw ratio into the said range.

A polyvinyl alcohol-based resin film dyed with a dichroic dye As a method, the method of immersing a polyvinyl-alcohol-type resin film in the aqueous solution containing a dichroic dye is mentioned, for example. As a dichroic dye, for example, iodine or a dichroic dye can be used. Among the dichroic dyes, for example, dichroic direct dyes containing disazo compounds such as C.I. Direct Red 39, and dichroic direct dyes containing trisazo, tetrasazo compounds, etc. are included. In addition, the polyvinyl alcohol-based resin film is preferably subjected to a treatment of immersion in water before the dyeing treatment.

When iodine is used as a dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is generally employed. The content of iodine in the aqueous solution is usually 0.01 to 1 part by mass based on 100 parts by mass of water, and the content of potassium iodide is usually 0.5 to 20 parts by mass based on 100 parts by mass of water. When iodine is used as a dichroic dye, the temperature of the aqueous solution used for dyeing is usually 20 to 40° C., and the immersion time (dyeing time) in the aqueous solution is usually 20 to 1800 seconds.

In addition, before immersing the polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide, the film may be immersed in water for swelling and easy dyeing. The immersion treatment temperature is usually 20 to 80°C, preferably 30 to 60°C, and the immersion time (dyeing time) is usually 20 to 1800 seconds.

When using a dichroic dye as a dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is generally employed. The dichroic dye content in the aqueous solution is usually 1×10 ^-4 to 10 parts by mass relative to 100 parts by mass of water, preferably 1×10 ^-3 to 1 part by mass, more preferably 1×10 ^-3 to 1×10 ^-2 parts by mass. The aqueous solution may contain inorganic salts such as sodium sulfate as dyeing aids. When a dichroic dye is used as the dichroic dye, the temperature of the dye aqueous solution used for dyeing is usually 20 to 80° C., and the immersion time (dyeing time) in the aqueous solution is usually 10 to 1800 seconds.

The boric acid treatment after dichroic dye dyeing can be performed by immersing the dyed polyvinyl alcohol-type resin film in a boric acid aqueous solution. The amount of boric acid in the boric acid aqueous solution is usually 2 to 15 parts by mass, preferably 5 to 12 parts by mass relative to 100 parts by mass of water. When using iodine as a dichroic dye, it is preferable that the boric acid aqueous solution contains potassium iodide. The amount of potassium iodide in the boric acid aqueous solution is usually 0.1 to 15 parts by mass, preferably 5 to 12 parts by mass relative to 100 parts by mass of water. The immersion time of the boric acid aqueous solution is usually 60 to 1200 seconds, preferably 150 to 600 seconds, more preferably 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually above 50°C, preferably 50 to 85°C, more preferably 60 to 80°C.

The polyvinyl alcohol-based resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol-based resin film in water. The temperature of water in the water washing treatment is usually 5 to 40° C., and the immersion time is usually 1 to 120 seconds. After washing with water, drying treatment was performed to obtain a polarizer. Drying can be performed using a hot air dryer or a far-infrared heater. The drying treatment temperature is usually 30 to 100°C, preferably 40 to 95°C, more preferably 50 to 90°C. The drying treatment time is usually 40 to 600 seconds, preferably 60 to 500 seconds, more preferably 120 to 400 seconds.

As described above, a polarizer can be obtained by uniaxially stretching a polyvinyl alcohol-based resin film, dyeing with a dichroic dye, and treating with boric acid.

The absorbance A ₇₀₀ of the polarizer obtained in this way at a wavelength of 700 nm is preferably 5.5 or less, more preferably 5.0 or less, still more preferably 4.5 or less, particularly preferably 4.2 or less. The absorbance A ₇₀₀ is related to the content of the I ₅ complex in the polarizer. If there is too much I ₅ complex, I ₃ ^- or I ^- iodide ions will be generated from the I ₅ complex in the durability test. Promote polyenylation reaction. Also, the absorbance A ₇₀₀ may be 3.0 or higher, preferably 3.5 or higher, and more preferably 3.7 or higher. If the absorbance A ₇₀₀ is too low, the I ₅ complex will collapse in the durability test and the relative amount will decrease, so the absorption near the wavelength of 700nm will be insufficient, and the polarizer will turn red. The absorbance A ₇₀₀ of the polarizer can be controlled, for example, by adjusting the temperature of water in the washing process when manufacturing the polarizer.

The absorbance _A700 of the polarizing plate can be measured using an absorbance photometer such as a UV-visible spectrophotometer, and can be calculated by the following formula.

A ₇₀₀ =-log[{TD transmittance in wavelength 700nm (%)}/100]

Incident light is measured using polarized light parallel to the absorption axis direction of the polarizer. In this formula, "TD transmittance" refers to the transmittance when the direction of polarization emitted by Glan-Thomson's is perpendicular to the transmission axis of the polarizer. For example, it can measure using the spectrophotometer V7100 with the integrating sphere manufactured by JASCO Corporation.

In a preferred aspect, the polarizer can be provided with a protective film (especially a transparent protective film) on at least one surface of the polarizer. The protective film helps prevent the shrinkage and expansion of the polarizer, and prevents the deterioration of the polarizer caused by temperature, humidity, ultraviolet rays, etc., so the preferred optical laminate of the present invention is at least a single layer of the polarizer The protective film is more preferably a protective film on both sides.

In terms of the material constituting the protective film, transparency, Excellent in mechanical strength, thermal stability, and/or isotropy. Examples include polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose-based polymers such as cellulose diacetate and cellulose triacetate, and acrylic acids such as polymethyl methacrylate. Styrene-based polymers such as polystyrene and acrylonitrile/styrene copolymer (AS resin), and polycarbonate-based polymers. Also, examples of polymers constituting the protective film include polyolefin polymers such as polyethylene, polypropylene, and ethylene/propylene copolymers, cyclic olefin polymers having a ring system or norbornene structure, chlorine Vinyl polymers, nylon and aromatic polyamides and other amide polymers, imide polymers, sulfide polymers, polyether ketone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, or any of the aforementioned polymers mixture etc. The protective film can be formed as a cured layer by thermosetting or ultraviolet curing resins such as acrylic, urethane, acrylic urethane, epoxy, and polysiloxane. Among them, those containing a hydroxyl group reactive with an isocyanate crosslinking agent are preferable, and cellulose-based polymers are particularly preferable.

The thickness of the protective film is not particularly limited, and is generally less than 500 μm, preferably 1 to 300 μm, more preferably 5 to 200 μm, and more preferably 10 to 100 μm. In addition, an optical compensation function can be added to the protective film.

The surface of the protective film not adjacent to the polarizer may have a surface treatment layer, for example, an optical layer such as a hard coat layer, an anti-reflection layer, an anti-adhesion layer, an anti-glare layer, or a diffusion layer. These optical layers can be bonded to the protective film through an adhesive layer composed of an adhesive described later.

The purpose of the hard coat layer is to prevent scratches on the surface of the polarizing plate. For example, it can be formed in the following manner: a cured film with excellent hardness and sliding properties formed by ultraviolet curable resins such as acrylic and polysiloxane Attached to the surface of the protective film. The purpose of the anti-reflection layer is to prevent the reflection of external light on the surface of the polarizing plate, which can be achieved by forming an anti-reflection film, which is standard in the past. Also, the purpose of the anti-adhesion layer is to prevent adhesion with adjacent layers.

In addition, the purpose of the anti-glare layer is to prevent the visual recognition of the light transmission of the polarizing plate from being hindered by the reflection of external light on the surface of the polarizing plate. Forms such as the form of fine particles are formed by providing a fine uneven structure on the surface of the protective film. The microparticles contained in the above-mentioned surface micro-concave-convex structure can be, for example, silicon dioxide, aluminum oxide, titanium dioxide, zirconium dioxide, tin oxide, indium oxide, cadmium oxide, antimony oxide, etc. with an average particle diameter of 0.5 to 50 μm. Transparent fine particles such as conductive inorganic fine particles, organic fine particles composed of cross-linked or non-cross-linked polymers, etc. When forming the fine uneven structure on the surface, the content of fine particles is usually 2 to 50 parts by mass, preferably 5 to 25 parts by mass relative to 100 parts by mass of the transparent resin forming the fine uneven structure on the surface. The anti-glare layer can also serve as a diffusion layer for diffusing the light transmitted by the polarizer to expand the viewing angle (viewing angle expansion function, etc.).

Furthermore, the aforementioned antireflection layer, anti-adhesion layer, diffusion layer, antiglare layer, etc. may be provided on the protective film itself to be integrated, or may be provided separately from the protective film as an optical layer. These optical layers can be bonded to the protective film through an adhesive layer composed of an adhesive described later.

In the present invention, the protective film preferably has a thickness of 200g/m ² . More than 24 hours of moisture permeability, more preferably 400g/m ² . More than 24 hours, more preferably 600g/m ² . More than 24 hours. When the water vapor transmission rate of a protective film is more than the said lower limit, the temporal yellowing of the optical layered body of this invention can be suppressed further. The protective film having a water vapor transmission rate of more than the above lower limit is preferably present on at least one side of the polarizer, more preferably present on both sides of the polarizer. The moisture permeability of the protective film is usually 2000g/m ² . Less than 24 hours. In addition, in the present invention, the water vapor transmission rate can be measured in accordance with JIS Z 0208:1976 under conditions of a temperature of 40°C and a humidity of 90%RH.

The polarizer and the protective film can be bonded through the adhesive layer. The adhesive agent which comprises an adhesive agent layer is not specifically limited, Various adhesive agents are mentioned. As for the adhesive, active energy ray-curable adhesives, water-based adhesives, organic solvent-based adhesives, and non-solvent-based adhesives are mentioned. Among them, active energy ray-curable adhesives and water-based adhesives are preferable from the viewpoint of forming a thin adhesive layer. Also, from the viewpoint of further suppressing the temporal yellowing of the optical laminate, a layer composed of an active energy ray-curable adhesive (hereinafter referred to as "active energy ray-curable adhesive layer") is more preferable, that is, Preferably, the polarizing plate includes a protective film laminated on at least one side of the polarizing plate or on both sides of the polarizing plate through an active energy ray-curable adhesive layer. When there are protective films on both sides of the polarizer, the adhesive coated on one surface of the polarizer may be the same as or different from the adhesive coated on the other surface of the polarizer. In addition, instead of the adhesive layer, the polarizer and the protective film can be attached through the adhesive layer formed by the adhesive described later.

Active energy ray hardening adhesives are cured by irradiating light, etc. Adhesive hardened by active energy rays. At this time, the obtained cured layer becomes an adhesive layer. Adhesives include active energy ray-curable adhesives containing epoxy compounds cured by cationic polymerization as curable components, and (meth)acrylic compounds cured by radical polymerization. Active energy ray hardening type adhesive etc.

Examples of epoxy-based compounds suitable for use include: alicyclic polyols obtained by hydrogenation of the aromatic rings of aromatic polyols, and epichlorohydrin reacted on the alicyclic polyols to obtain hydrogenated Epoxy compounds (glycidyl ethers of polyols having an alicyclic ring); aliphatic epoxy compounds such as polyglycidyl ethers of aliphatic polyols or their alkylene oxide adducts; and molecules An alicyclic epoxy-based compound of an epoxy-based compound having one or more epoxy groups bonded to an alicyclic ring.

The active energy ray-curable adhesive agent may further contain a radically polymerizable (meth)acrylic compound as a curable component. Examples of (meth)acrylic compounds include: (meth)acrylate monomers having at least one (meth)acryloxy group in the molecule; reacting two or more compounds containing functional groups, and in the molecule Compounds containing (meth)acryloxy groups such as (meth)acrylate oligomers having at least 2 (meth)acryloxy groups in them.

When the active energy ray-curable adhesive contains an epoxy-based compound cured by cationic polymerization as a curable component, it is preferable to contain a photocationic polymerization initiator. The photocationic polymerization initiator may, for example, be an aromatic diazonium salt; an onium salt such as an aromatic iodonium salt or an aromatic permeic acid salt; or an iron/arene complex. Also, the active energy ray curing type adhesive contains (meth)acrylic acid When it is a radically polymerizable curable component such as a compound, it is preferable to contain a photoradical polymerization initiator. Examples of photoradical polymerization initiators include acetophenone-based initiators, benzophenone-based initiators, benzoin ether-based initiators, thioxanthone-based initiators, xanthrone, fennelone, and camphor. quinones, benzaldehydes, and anthraquinones.

Active energy ray hardening adhesives may contain cationic polymerization accelerators such as oxetane and polyols, photosensitizers, ion traps, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, Additives for flow regulators, plasticizers, defoamers, antistatic agents, leveling agents, and/or solvents.

When an active energy ray-curable adhesive is used, the active energy ray-curable adhesive is cured by irradiating active energy rays. The light source of the active energy line is not particularly limited, but it is preferably an active energy line with a luminescence distribution below a wavelength of 400nm, specifically, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, and a black light Lamps, microwave excited mercury lamps, and metal halide lamps.

The intensity of light irradiation on the active energy ray-curable adhesive is appropriately determined according to the composition of the active energy ray-curable adhesive, and is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is preferable 0.1 to 6000mW/cm ² , more preferably 10 to 1000mW/cm ² , and more preferably 20 to 500mW/cm ² . If the irradiation intensity is within the above range, the reaction time can be ensured, and the yellowing of the epoxy resin or the deterioration of the polarizer caused by the radiant heat from the light source and the heat generated when the active energy ray-curable adhesive is hardened can be suppressed. The light irradiation time for the active energy ray-curable adhesive can be appropriately selected according to the active energy ray-curable adhesive to be cured, and is not particularly limited, but it is preferably set so that it represents the accumulation of the product of the above-mentioned irradiation intensity and irradiation time The amount of light is 10 to 10000 mJ/m ² , more preferably 50 to 1000 mJ/m ² , still more preferably 80 to 500 mJ/m ² . If the cumulative light intensity on the active energy ray-curable adhesive is within the above-mentioned range, a sufficient amount of active species derived from the polymerization initiator can be generated, and the hardening reaction can be performed more reliably, and the irradiation time will not be too long And can maintain good productivity.

In addition, when the active energy ray-curable adhesive is cured by irradiating active energy rays, it is preferable to use materials that do not affect the degree of polarization, transmittance, and hue of the polarizer, and various films constituting the protective film and the optical layer, for example. Curing is performed under the condition that the various functions of the polarizing plate such as transparency are lowered.

Water-based adhesives are obtained by dissolving the adhesive components in water, or in a mixed solvent of water and a hydrophilic organic solvent (such as alcohol solvent, ether solvent, ester solvent, etc.), or by dispersing the adhesive components in water. As an adhesive component, the adhesive containing polyvinyl-alcohol-type resin or urethane resin is mentioned, for example. Also, the organic solvent-based adhesive is a water-based adhesive that uses an organic solvent instead of water, or a mixed solvent of water and a hydrophilic organic solvent.

Examples of water-based adhesives include polyvinyl alcohol-based resin adhesives, water-based two-component urethane-based emulsion adhesives, and the like. Moreover, as an organic solvent type adhesive agent, a two-component type urethane type adhesive agent etc. are mentioned, for example. On the other hand, examples of the non-solvent-based adhesive include one-component urethane-based adhesives and the like.

When the adhesive contains polyvinyl alcohol-based resin as the adhesive component, the polyvinyl alcohol-based resin can be carboxy-modified polyvinyl alcohol, acetoacetyl-modified Modified polyvinyl alcohol-based resins such as polyvinyl alcohol, methylol-modified polyvinyl alcohol, and amine-modified polyvinyl alcohol. Usually, the adhesive system that uses polyvinyl alcohol resin as the adhesive component is prepared as an aqueous solution of polyvinyl alcohol resin. The concentration of the polyvinyl alcohol-based resin in the adhesive is usually 1 to 10 parts by mass, preferably 1 to 5 parts by mass relative to 100 parts by mass of water.

In order to improve adhesiveness, the adhesive containing polyvinyl alcohol-based resin as the adhesive component preferably contains hardening components such as glyoxal and water-soluble epoxy resin and/or a crosslinking agent. In terms of water-soluble epoxy resins, polyamide polyamine epoxy resins are suitable for use. The polyamide polyamine epoxy resins are, for example, polyalkylene polyamines such as diethylenetriamine and triethylenetetramine mixed with adipic acid. The polyamide amine is obtained by reacting dicarboxylic acids, and the polyamide amine is reacted with epichlorohydrin. Commercially available polyamide polyamine epoxy resins include "Sumirez Resin 650" (manufactured by Taoka Chemical Industry Co., Ltd.), "Sumirez Resin 675" (manufactured by Tamoka Chemical Industry Co., Ltd.), "WS -525" (manufactured by Japan PMC Co., Ltd.), etc. The addition amount of these curable components and/or crosslinking agents (the total amount when added together) is usually 1 to 100 parts by mass, preferably 1 to 50 parts by mass, relative to 100 parts by mass of polyvinyl alcohol-based resin . When the addition amount of the said hardening component and/or crosslinking agent is in the said range, adhesiveness can be improved, and the adhesive agent layer which shows good adhesiveness can be formed.

Also, when a urethane resin is contained as an adhesive component, it is preferable to use a mixture of a polyester-based ionomer type urethane resin and a compound having a glycidoxy group. Here, the polyester-based ionomer type urethane resin is a urethane resin having a polyester backbone and A small amount of ionic components (hydrophilic components) are introduced into its skeleton. The ionic polymer type urethane resin can be directly emulsified in water to form an emulsion without using an emulsifier, so it is suitable as a water-based adhesive. Polyester-based ionomer-type urethane resin itself is known, for example, in Japanese Patent Application Laid-Open No. 7-97504, it is described as an example of a polymer dispersant for dispersing a phenolic resin in an aqueous medium, In addition, Japanese Patent Application Laid-Open No. 2005-70140 and Japanese Patent Application Laid-Open No. 2005-208456 disclose the following form: a mixture of a polyester ionomer type urethane resin and a compound having a glycidoxy group is used as an adhesive agent, and a cyclic olefin-based resin film is bonded to a polarizer made of polyvinyl alcohol-based resin.

In addition, a water-soluble chelate compound may be contained as an adhesive component. The water-soluble chelate compound contained in the adhesive composition can increase the degree of cross-linking between the adhesive layer and protective films such as polyvinyl alcohol-based polarizers, cellulose-based films, and olefin-based films, thereby improving adhesive force and water resistance. As the water-soluble chelate compound system, zinc chloride, cobalt chloride, magnesium chloride, magnesium acetate, aluminum nitrate, zinc nitrate, zinc sulfate, etc. can be added. In particular, zinc chloride and zinc nitrate are preferred from the viewpoint of improving durability.

Applying the adhesive to the polarizer and/or the protective film bonded to the polarizer can be carried out by known methods, such as casting method, wire bar coating method, gravure coating method, chipping wheel method, doctor blade method, Die coating method, dip coating method, spray method, etc. The casting method refers to a method of spreading an adhesive on the surface while moving the film of the object to be coated in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two. After applying the adhesive, overlap the polarizer and the protective film attached to the polarizer, and use a nip roller, etc. The lamination of the film is carried out by sandwiching. For lamination of films using nip rolls, for example, the method of applying pressure with a roller etc. after applying the adhesive and uniformly applying pressure to expand, and the method of applying pressure between rollers after applying the adhesive and applying pressure to expand wait. The material of the roller used at this time may be metal or rubber. Also, when the film is expanded by applying pressure between a plurality of rollers, the plurality of rollers may be made of the same material or different materials.

After the above lamination, dry and harden the adhesive to obtain a polarizing plate including a polarizer, an adhesive layer, and a protective film. The drying treatment is carried out, for example, by blowing hot air. The temperature varies depending on the type of solvent, but is usually in the range of 30 to 200°C, preferably 35 to 150°C, more preferably 40 to 100°C, and more preferably Preferably it is 60 to 100°C. Also, the drying time is usually 20 to 1200 seconds.

After drying, cure the adhesive layer at a temperature above room temperature for at least half a day, preferably several days or more to obtain sufficient adhesive strength. The aging temperature is preferably in the range of 30 to 50°C, more preferably in the range of 35 to 45°C. If the curing temperature is within the aforementioned range, so-called "tight winding" is less likely to occur in the coiled state. Also, the humidity during aging is not particularly limited as long as the relative humidity is in the range of 0 to 70%RH. The aging time is usually half a day to 20 days, preferably 1 to 10 days, more preferably 2 to 7 days.

In addition, surface treatments such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, and saponification treatment may be appropriately performed on the bonding surface between the polarizer and the protective film in order to improve adhesion. The saponification treatment includes a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide.

The thickness of the adhesive layer is usually 0.001 to 10 μm, preferably 0.01 to 5 μm, more preferably 0.01 to 2 μm, and more preferably 0.02 to 1 μm. If the thickness of the adhesive layer is within the above range, sufficient adhesiveness can be ensured, and the appearance is also better, and it can further contribute to the thinning of the polarizing plate, so it is suitable for the optical laminate of the present invention.

In the optical laminate of the present invention, the polarizing plate may be further laminated with optical films or optical layers such as retardation film, viewing angle compensation film, brightness enhancement film, antiglare film, antireflection film and/or light concentrating film. These optical films and optical layers can be attached to the polarizing plate through the adhesive layer composed of the adhesive described later.

Retardation film is an optical film showing optical anisotropy. Retardation film can include birefringence film formed by uniaxial or biaxial stretching of polymer materials, alignment film of liquid crystal polymer, liquid crystal polymer The alignment layer of the object is supported by the film, etc. The stretching treatment can be performed, for example, by a roll stretching method, a long nip stretching method, a tenter stretching method, a tubular stretching method, or the like. The draw ratio is generally 1.1 to 3 times in the case of uniaxial stretching. The thickness of the retardation film is not particularly limited, but is generally 10 to 200 μm, preferably 20 to 100 μm.

Polymer materials such as polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate , Polyarylate, Polyethylene, Polyethylene Terephthalate, Polyethylene Naphthalate, Polyether, Polyphenylene Sulfide, Polyphenylene Ether, Polyallyl, Polyvinyl Alcohol, Polyamide Amines, polyimides, polyolefins, polyolefins with a norcamphene structure, polyvinyl chloride, cellulose-based polymers, or various copolymers and graft copolymers of these binary or ternary systems, mixture etc. These polymer materials can be Stretching or the like to become an aligned object (stretched film).

Examples of liquid crystal polymers include various polymers of the main chain type or side chain type in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. Specific examples of main-chain liquid crystal polymers include polyester-based liquid crystal polymers with nematic alignment, discotic polymers, or cholesterol, which have a structure in which mesogen groups are bonded to spacers that impart flexibility. polymers etc. Specific examples of side chain type liquid crystal polymers include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as the main chain skeleton, and have a mesogenic portion as a side chain. The moiety includes a para-substituted cyclic compound unit that imparts nematic alignment through a spacer portion formed of a conjugated atomic group. These liquid crystal polymers can be, for example, rubbing the surface of polyimide or polyvinyl alcohol film formed on a glass plate, or obliquely vapor-depositing silicon oxide. polymer solution and heat treatment.

For example, for the purpose of compensating for coloring or viewing angle due to birefringence of various wavelength plates or liquid crystal layers, etc., the retardation film can have a retardation according to the purpose of use, and the retardation can also be controlled by laminating two or more retardation films. and other optical properties.

The viewing angle compensation film is a film used to expand the viewing angle. Even when the liquid crystal display device screen is viewed in a direction slightly oblique to the screen, images can be viewed more clearly.

Such a viewing angle compensation film includes, for example, a retardation film, a liquid crystal polymer, or other dominant film, or a transparent substrate that supports an alignment layer of a liquid crystal polymer or the like. A common retardation film uses a double-layer film with uniaxial stretching in its plane direction. Refractive polymer film, for this, the retardation film used as the viewing angle compensation film is used: a polymer film having birefringence stretched biaxially in the plane direction, and a polymer film stretched uniaxially in the plane direction and also in the thickness direction Stretched polymers with birefringence to control the refractive index in the thickness direction, or biaxially stretched films such as oblique alignment films, etc. The oblique alignment film can be, for example, a polymer film followed by a heat-shrinkable film, and the polymer film is stretched or/and shrunk under the action of the shrinkage force by heating, or a liquid crystal polymer is obliquely aligned. The raw material polymer of the phase difference film is the same as the polymer described above for the phase difference film, in order to prevent coloring due to the change of the viewing angle of the phase difference of the liquid crystal cell, etc., and to expand the viewing angle for better visual recognition, etc. Can be used appropriately.

Also, from the perspective of achieving better visual recognition and wide viewing angles, it is suitable to use a viewing angle compensation film, which is an optical angle compensation film composed of an alignment layer of a liquid crystal polymer, especially an oblique alignment layer of a discotic polymer. The anisotropic layer is supported by a cellulose triacetate membrane.

<Adhesive layer>

In the present invention, the first adhesive layer and the second adhesive layer are respectively laminated on the surface of the polarizing plate. The first adhesive layer and the second adhesive layer are composed of adhesives. The adhesives constituting the first adhesive layer and the second adhesive layer may be the same or different.

In the present invention, the adhesive is made of resin. The type of resin contained in the adhesive is not particularly limited, and examples thereof include (meth)acrylic resin, silicone resin, urethane resin, and rubber. Adhesive system can Contains single or plural resins.

It is preferable to use (meth)acrylic resin (A) as the above-mentioned resin at the point that functionality can be easily imparted to the adhesive by selecting the type of monomer introduced into the resin. In terms of the (meth)acrylic resin (A), for example, a structural unit derived from a (meth)acrylate represented by the following formula (I) (hereinafter also referred to as "monomer (I)") is The main component is polymer. Also, in the present invention, "a polymer mainly composed of a structural unit derived from monomer (I)" means that the structural unit derived from monomer (I) is less than all structural units constituting the polymer. Preferably, it contains 40 mass % or more, More preferably, it contains 60 mass % or more, for example, 80 mass % or more. In this case, the structural unit derived from the monomer (I) is usually contained in an amount of 100% by mass or less, preferably 90% by mass or less, based on all structural units constituting the polymer.

In formula (I), R ¹ is a hydrogen atom or a methyl group, and R ² is usually an alkyl or aralkyl group having 14 or less carbon atoms, preferably 10 or less, and usually 1 or more.

In one embodiment of the present invention, the (meth)acrylic resin (A) may further contain other structural units besides the structural unit derived from (meth)acrylate (monomer (I)), especially The structural unit derived from a monomer having a polar functional group is preferably a structural unit derived from a (meth)acrylic compound having a polar functional group. Examples of the polar functional group include a carboxyl group, a hydroxyl group, an amino group, and a heterocyclic group including an epoxy ring. Polar function The base (meth)acrylic compound includes, for example, (meth)acrylic acid, 2-(dimethylamino)ethyl acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl acrylate, and the like. Moreover, a (meth)acrylic resin (A) may contain the structural unit derived from the monomer which does not have a polar functional group other than a monomer (I). Suitable structural units (monomers) include structural units derived from monomers having one olefinic double bond and at least one aromatic ring in the molecule, preferably derived from monomers having an aromatic ring (a base) a structural unit of an acrylic compound. In addition, in this specification, (meth)acrylic acid means either acrylic acid or methacrylic acid, and "(meth)" in the case of (meth)acrylate etc. is also the same.

In the monomer (I), R ² is an alkyl group. More specifically, straight-chain forms such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, n-octyl acrylate, and lauryl acrylate can be mentioned. Alkyl acrylate; branched alkyl acrylate such as isobutyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, methyl Linear alkyl methacrylates such as n-butyl acrylate, n-octyl methacrylate, and lauryl methacrylate; and isobutyl methacrylate, 2-ethylhexyl methacrylate, and methacrylic acid Branched alkyl methacrylates such as isooctyl ester.

Among these, n-butyl acrylate is preferred, and specifically, it is preferred that n-butyl acrylate in all structural units (monomers) constituting (meth)acrylic resin (A) is 50% by mass or more and satisfies the relevant The provisions of the aforementioned monomer (I).

In the monomer (I), R ² is an aralkyl group. Specific examples thereof include benzyl acrylate, benzyl methacrylate, and the like.

These monomers (I) can be used alone or in combination, respectively.

The alkyl group or aralkyl group constituting R ² in the aforementioned formula (I) may be one whose hydrogen atom is substituted with -O-(C ₂ H ₄ O) _n -R ³ group.

When the hydrogen atom of the alkyl group or _aralkyl group constituting ^R2 in the aforementioned formula (I) is substituted by the group -O-( _C2H4O ) _n - ^R3 , n is preferably 0 or an integer from 1 to 4, More preferably, it is 0, 1 or 2. Also, as long as R ³ is an alkyl or aryl group having 12 or less carbon atoms and the alkyl group has 3 or more carbon atoms, it may be straight or branched. Examples of the aryl group constituting ^R3 include, in addition to phenyl or naphthyl, nucleoalkyl-substituted phenyl, biphenyl (or phenylphenyl), etc. . R ³ is particularly preferably such an aryl group.

In the formula (I) ^{, R2} is an alkyl or aralkyl group and the hydrogen atom of the alkyl or _aralkyl group of ^R2 is replaced by -O-( _C2H4O ) _n - ^R3 (meth)acrylic acid Specifically, for example, 2-methoxyethyl acrylate, ethoxymethyl acrylate, 2-phenoxyethyl acrylate, 2-(2-phenoxyethoxy)ethyl acrylate, and acrylic acid Alkoxyalkyl, aryloxyalkyl, or aryloxyethoxyalkyl acrylate such as 2-(o-phenylphenoxy)ethyl; 2-methoxyethyl methacrylate, methyl Ethoxymethyl acrylate, 2-phenoxyethyl methacrylate, 2-(2-phenoxyethoxy)ethyl methacrylate, and 2-(o-phenylphenoxy ) alkoxyalkyl esters of methacrylic acid such as ethyl ester, aryloxyalkyl esters, or aryloxyethoxyalkyl esters, etc.

In the present invention, the (meth)acrylic resin (A) may contain a structural unit derived from a monomer having no polar functional group other than the monomer (I). Monomers other than the monomer (I) that do not have a polar functional group include (meth)acrylate monomers having an alicyclic structure in the molecule, styrene-based monomers, etc. Monomers, vinyl monomers, (meth)acrylamide derivatives, and monomers with multiple (meth)acrylamide groups in the molecule, etc.

A (meth)acrylate monomer having an alicyclic structure in the molecule is described. The alicyclic structure refers to a cycloalkane structure usually having 5 or more carbon atoms, preferably about 5 to 7 carbon atoms. Specific examples of acrylate monomers having an alicyclic structure include isobornyl acrylate, cyclohexyl acrylate, dicyclopentyl acrylate, cyclododecyl acrylate, methylcyclohexyl acrylate, trimethyl acrylate Cyclohexyl, tert-butylcyclohexyl acrylate, α-ethoxycyclohexyl acrylate, cyclohexylphenyl acrylate, and the like. In addition, specific examples of methacrylate monomers having an alicyclic structure include isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentyl methacrylate, and cyclododecyl methacrylate. , methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, cyclohexylphenyl methacrylate, etc.

Examples of styrene-based monomers include methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, and propylstyrene in addition to styrene. Alkylstyrenes such as styrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene; fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene, etc. Halogenated styrene; and nitrostyrene, acetylstyrene, methoxystyrene, divinylbenzene, etc. are also mentioned.

Examples of vinyl monomers include fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, and vinyl laurate; halogenated vinyl chloride or vinyl bromide, etc. vinyl; Vinylene halides such as vinyl chloride; nitrogen-containing aromatic vinyls such as vinylpyridine, vinylpyrrolidone, and vinylcarbazole; conjugated diene monomers such as butadiene, isoprene, and chloroprene body; and acrylonitrile, methacrylonitrile, etc. can also be mentioned.

Examples of (meth)acrylamide derivatives include N-methylol(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, N-(3-hydroxy Propyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, N-(5-hydroxypentyl)(meth)acrylamide, N-(6- Hydroxyhexyl)(meth)acrylamide, N-(methoxymethyl)(meth)acrylamide, N-(ethoxymethyl)(meth)acrylamide, N-(propoxy methyl)(meth)acrylamide, N-(butoxymethyl)(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl N-(meth)acrylamide, N-isopropyl(meth)acrylamide, N-(3-dimethylaminopropyl)(meth)acrylamide, N-(1,1- Dimethyl-3-oxobutyl)(meth)acrylamide, N-[2-(2-oxo-1-imidazolidinyl)ethyl](meth)acrylamide, 2 -Acrylamino-2-methyl-1-propanesulfonic acid and the like.

Examples of monomers having multiple (meth)acryl groups in the molecule include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1 , 9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and Tripropylene glycol di(meth)acrylate and other monomers with 2 (meth)acryl groups in the molecule; trimethylolpropane tri(meth)acrylate and other monomers with 3 (meth)acryl groups in the molecule The monomer of the base, etc.

The monomers constituting the (meth)acrylic resin (A) may contain There are two or more types of (meth)acrylates represented by the above formula (I), and optionally monomers having polar functional groups and/or monomers other than monomers (I) that do not have polar functional groups.

The resin contained in the adhesive is not particularly limited in terms of weight average molecular weight Mw in terms of standard polystyrene as measured by gel permeation chromatography (GPC), but the Mw is preferably in the range of 500,000 to 2 million, more preferably Those in the range of 500,000 to 1.8 million. If the standard polystyrene-equivalent weight average molecular weight is more than 500,000, the adhesiveness under high temperature and high humidity will be improved, and the possibility of floating or peeling between the transparent plate or the image display unit and the adhesive layer will tend to be reduced. And the reworkability also tends to be improved. In addition, if the weight average molecular weight is 2 million or less, even if the size of the protective film attached to the adhesive layer changes, the adhesive layer will also change with the size change, so the brightness of the peripheral portion of the liquid crystal cell and There is no difference in luminance at the center, and white spots and color unevenness tend to be suppressed, which is preferable. The molecular weight distribution represented by the ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn is not particularly limited, but is preferably within a range of about 3 to 15, for example.

The resin contained in the adhesive can be produced by various known methods such as solution polymerization, emulsion polymerization, block polymerization, and suspension polymerization, for example. A polymerization initiator can be used for resin production, and its addition amount is about 0.001 to 5 mass parts with respect to a total of 100 mass parts of all monomers used for resin production.

As the polymerization initiator, a thermal polymerization initiator, a photopolymerization initiator, or the like can be used. Photopolymerization initiators such as 4-(2-hydroxyethoxy)phenyl (2-Hydroxy-2-propyl) ketone, etc. Examples of thermal polymerization initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane- 1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile ), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis(2-hydroxymethylpropionitrile) and other azo compounds; lauryl Peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl benzoate peroxide, cumene hydroperoxide, diisopropyl dicarbonate peroxide, peroxydicarbonate Organic peroxides such as dipropyl oxide, tert-butyl neodecanoate peroxide, tert-butyl peroxypivalate, and (3,5,5-trimethylhexyl) peroxide; Potassium sulfate, ammonium persulfate, and inorganic peroxides such as hydrogen peroxide, etc. Moreover, a redox system initiator which uses a peroxide and a reducing agent together can also be used as a polymerization initiator.

In terms of the production method of the (meth)acrylic resin (A), the solution polymerization method is preferable among the methods shown above. When citing a specific example of the solution polymerization method, the following method can be mentioned: mixing the desired monomer and an organic solvent, adding a thermal polymerization initiator under a nitrogen atmosphere, and setting the temperature at about 40 to 90°C, preferably 50 to 50°C. Stir at about 80°C for about 3 to 15 hours. In addition, in order to control the reaction, a monomer or a thermal polymerization initiator may be added continuously or intermittently during polymerization, or may be added in a state of being dissolved in an organic solvent. Here, as an organic solvent, for example, aromatic hydrocarbons such as toluene or xylene; esters such as ethyl acetate or butyl acetate; aliphatic alcohols such as propanol or isopropanol; acetone, methyl ethyl ketone, etc. , and ketones such as methyl isobutyl ketone, etc.

In the present invention, the adhesive constituting the adhesive layer may contain other additives in addition to the resins described above. For other additives, the Such as crosslinking agent, silane compound, crosslinking catalyst, weathering stabilizer, tackifier, plasticizer, softener, dye, pigment, inorganic filler, organic acid, antistatic agent, and organic acid metal salt, etc.

In addition, it is also useful to mix an active energy ray (for example, ultraviolet ray) curable compound with the adhesive, and after forming the adhesive layer, irradiate the ultraviolet ray to harden it to form a harder adhesive layer.

The cross-linking agent that the adhesive can contain is a compound that can have at least 2 functional groups in the molecule that can cross-link with the resin contained in the adhesive. Specifically, an isocyanate compound, an epoxy compound, a metal chelate compound, an aziridine compound, etc. are mentioned.

Isocyanate compounds are compounds with at least 2 isocyanate groups (-NCO) in the molecule, such as cresyl diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate , Hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, etc. In addition, the crosslinking agent used in the adhesive may also be an adduct of these isocyanate compounds reacted with polyhydric alcohols such as glycerin or trimethylolpropane, or a dimer or trimer of isocyanate compounds. Two or more types of isocyanate compounds may be used in combination.

Epoxy compounds are compounds with at least 2 epoxy groups in the molecule, such as bisphenol A type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether , Glycerin Diglycidyl Ether, Glycerin Triglycidyl Ether, 1,6-Hexanediol Diglycidyl Ether, Trimethylolpropane Triglycidyl Ether, N,N-Diepoxy Propylaniline, N,N,N',N'- Tetraglycidyl-m-xylylenediamine, etc. Two or more epoxy-based compounds can be used in combination.

Examples of metal chelate compounds include acetyl acetone and ethyl acetyl acetate coordinated to polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. compounds etc.

The aziridine-based compound is a compound having at least two skeletons called ethyleneimine in the molecule. The ethyleneimine is a 3-membered ring composed of 1 nitrogen atom and 2 carbon atoms. For example, Diphenylmethane-4,4'-bis(1-aziridinecarboxamide), toluene-2,4-bis(1-aziridinecarboxamide), triethylenemelamine, m-phthalamide Acylbis-1-(2-methylaziridine), tri-1-aziridine phosphine oxide, hexamethylene-1,6-bis(1-aziridine carboxamide), tris Methylolpropane tris-β-aziridinyl propionate, tetramethylolmethane tris-β-aziridinyl propionate, and the like.

Among these crosslinking agents, it is preferable to use isocyanate-based compounds, especially adducts of cresyl diisocyanate and polyols, dimers of cresyl diisocyanate, and trimers of cresyl diisocyanate , Addition of hexamethylene diisocyanate and polyol reaction, dimer of hexamethylene diisocyanate, trimer of hexamethylene diisocyanate, addition of xylene diisocyanate and polyol reaction products, adducts of hydrogenated xylylene diisocyanate and polyols, isophorone diisocyanate and/or adducts of isophorone diisocyanate and polyols, mixtures of these isocyanate compounds, etc.

The content of the above-mentioned crosslinking agent in the adhesive is usually about 0.01 to 5 parts by mass relative to 100 parts by mass of the resin contained in the adhesive, preferably 0.03 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass.

When the optical layered body of the present invention is bonded to a transparent plate (for example, a glass plate) through an adhesive, the adhesive in the present invention preferably contains a silane compound from the viewpoint of improving the adhesiveness with the glass substrate. It is especially preferable that the resin contains a silane compound before compounding the crosslinking agent.

Silane-based compounds can be, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxysilane, 3-Glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-Chloropropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3 -Glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropylethoxydimethylsilane, etc. Two or more types of silane-based compounds can be used.

The silane compound can be polysiloxane oligomer type. When the polysiloxane oligomer is expressed as a (monomer)-(monomer) copolymer, the following are examples.

3-Mercaptopropyltrimethoxysilane-Tetramethoxysilane Copolymer, 3-Mercaptopropyltrimethoxysilane-Tetraethoxysilane Copolymer, 3-Mercaptopropyltriethoxysilane-Tetramethoxysilane Copolymers containing mercaptopropyl groups such as 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymers and 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymers; mercaptomethyltrimethoxysilane-tetramethoxysilane copolymers mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane Copolymers and other copolymers containing mercaptomethyl; 3-methacryloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropyltrimethoxysilane-tetramethoxysilane Ethoxysilane copolymer, 3-methacryloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropyltriethoxysilane-tetraethoxysilane silane copolymer, 3-methacryloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropylmethyldimethoxysilane-tetramethoxysilane Ethoxysilane copolymer, 3-methacryloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloxypropylmethyldiethoxy Silane-tetraethoxysilane copolymer and other copolymers containing methacryloxypropyl; 3-acryloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloxy Propyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropyltriethoxysilane -tetraethoxysilane copolymer, 3-acryloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropylmethyldimethoxysilane-tetramethoxysilane Ethoxysilane copolymer, 3-acryloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloxypropylmethyldiethoxysilane-tetraethoxysilane Oxysilane copolymers and other copolymers containing acryloxypropyl groups; vinyltrimethoxysilane-tetramethoxysilane copolymers, vinyltrimethoxysilane-tetraethoxysilane copolymers, vinyltrimethoxysilane-tetraethoxysilane copolymers, Ethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, vinyl methyl Dimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer Copolymers containing vinyl, etc.

Most of these silane-based compounds are liquid. The content of the silane compound in the adhesive is usually about 0.01 to 10 parts by mass, preferably 0.03 to 2 parts by mass, and more preferably 0.03 to 1 part by mass relative to 100 parts by mass of the resin contained in the adhesive.

The thickness of the first adhesive layer and the thickness of the second adhesive layer may be the same or different from each other. The thickness of the first adhesive layer and the thickness of the second adhesive layer are as previously explained, as long as the relationship between the thickness (T2) of the polarizer is the ratio of the total thickness T1 and T2 of all adhesive layers in the optical laminate (T2/T1) is 0.6 or less, and can be determined appropriately each independently.

In one embodiment, the optical laminate of the present invention can be attached to the image display unit described later through the first adhesive layer, and can also be attached to the transparent plate described later through the second adhesive layer. At this time, the thickness of the second adhesive layer and the thickness of the first adhesive layer may be the same or different, and the thickness of the second adhesive layer may be thicker than that of the first adhesive layer.

From the viewpoint of suppressing yellowing of the optical laminate, the thickness of the first adhesive layer (adhesive layer on the cell side) is preferably at least 3 μm, more preferably at least 5 μm, and more preferably at least 10 μm. From the viewpoint of stratification, etc., it is preferably 30 μm or less, more preferably 27 μm or less, Still more preferably, it is 25 μm or less. Also, from the viewpoint of suppressing yellowing of the optical laminate, the thickness of the second adhesive layer (adhesive layer on the transparent plate side) is preferably at least 20 μm, more preferably at least 30 μm, and more preferably at least 40 μm. From the viewpoint of thinning the layered body, etc., it is preferably at most 300 μm, more preferably at most 280 μm, and even more preferably at most 250 μm. Also, when the optical layered body contains an adhesive layer other than the first adhesive layer and the second adhesive layer (also referred to as "other adhesive layer"), from the viewpoint of suppressing yellowing of the optical layered body, etc., the other The adhesive layer is preferably 3 μm or more, more preferably 5 μm or more, and is preferably 30 μm or less, more preferably 25 μm or less, from the viewpoint of thinning the optical laminate.

In the optical laminate of the present invention, peelable protective sheets may be attached to the surfaces of the first adhesive layer and the second adhesive layer opposite to the polarizing plate, respectively. The protective sheet is used for the purpose of preventing damage and dirt on the exposed surface of the adhesive layer before bonding the optical laminate to the image display unit or the transparent plate. The image display device of the present invention can be constructed by peeling off the protective sheet and, for example, attaching the first adhesive layer to the image display unit and the second adhesive layer to the transparent plate. That is, both the first adhesive layer and the second adhesive layer can be assembled in the display device without being removed.

Materials constituting the protective sheet can be, for example, thermoplastic resins, such as polyolefin resins such as polyethylene resin and polypropylene resin; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polycarbonate resins; (meth)acrylic resin, etc.

The optical layered body of the present invention is used, for example, by being bonded between a transparent plate and an image display unit through the above-mentioned adhesive layer. transparent board It is responsible for suppressing warping of image display units such as liquid crystal units, or protecting image display units, such as light-transmitting (preferably optically transparent) plate-like bodies. The transparent sheet can be of a single-layer construction or a multi-layer construction. The transparent board is also called a transparent front panel. As an image display unit, a liquid crystal unit (element), an organic EL unit (element), etc. are mentioned.

Since the transparent plate is placed on the outermost surface of the final product containing the optical laminate of the present invention, it is required to exhibit sufficient durability even when used outdoors or semi-outdoors. From this point of view, the transparent plate is preferably composed of an inorganic material such as glass or tempered glass, and a polymer film having a Young's modulus of 2 GPa or more. Inorganic materials such as glass and strengthened glass are preferred, especially in terms of flexible display applications, polymer films are preferred, among which polycarbonate resin (Young's modulus 2 to 3GPa), acrylic resin (Young's modulus 2 to 3GPa), acrylic resin (Young Modulus 3 to 4GPa), polyimide resin (Young's modulus 3 to 5GPa), polyether resin (Young's modulus 2 to 3GPa).

The above-mentioned transparent plate may have a color filter layer or a TFT layer in a display, a transparent electrode layer in a touch panel, or a glass or polymer film printed with a decorative layer. That is, in one embodiment of the present invention, the transparent plate may have at least one pattern layer selected from the group consisting of the following (A) to (D) on at least one side thereof.

(A) Color filter layer.

(B) TFT layer.

(C) Transparent electrode layer.

(D) Decorative layer.

The method of the touch panel is not particularly limited, and examples include capacitive method, surface acoustic wave method, resistive film method, electromagnetic induction method, Light sensor method, infrared method, etc. The aforementioned transparent plate may have functions such as anti-reflection, anti-fouling, electromagnetic wave shielding, near-infrared ray shielding, color adjustment, or prevention of glass scattering. The transparent plate with this function can be, for example, at least one film layer with these functions on at least one area of the above-mentioned transparent plate.

The integration of the transparent plate, the polarizing plate, and the image display unit can be realized by laminating them through the above-mentioned adhesive layer, whereby an image display device including the optical laminate of the present invention (also referred to as "the present invention") can be provided. image display device"). In the image display device, in order to eliminate reflection or light scattering at the interface between the transparent plate and the polarizing plate and improve visibility, the refractive index of the adhesive is preferably close to or the same as that of the transparent plate. In the image display device of the present invention, the yellowing of the image display part (display) over time can be suppressed, and a long-term stable image display function can be exhibited.

The optical laminate and image display device of the present invention can be used in portable devices such as televisions, personal computers, mobile phones, and tablet terminals, because it has a high inhibitory effect on yellowing under high-temperature environments, and can exhibit long-term The image display function is stable during the period, so it is especially suitable for use in automobiles that are easily exposed to more severe temperature conditions. Examples of automotive applications include image display devices used in car navigation devices, speedometers, touch panels for air conditioners, rear monitors, and rear displays.

[Example]

The following examples and comparative examples are given to further describe the present invention in detail.

1. Production of polarizer (1)

A polyvinyl alcohol film with a thickness of 60 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 by dry stretching, and then immersed in pure water at 60°C while maintaining the tension After soaking for 1 minute, immerse in an aqueous solution at 28°C with a mass ratio of iodine/potassium iodide/water of 0.05/5/100 for 60 seconds. Thereafter, it was immersed in a 72° C. aqueous solution whose mass ratio of potassium iodide/boric acid/water was 8.5/8.5/100 for 300 seconds. Then, after washing with pure water at 26° C. for 20 seconds, it was dried at 65° C. for 60 seconds to obtain a polarizer (1) with a thickness of 23 μm in which iodine was adsorbed and aligned on the polyvinyl alcohol film. The absorbance A ₇₀₀ of the polarizer (1) at a wavelength of 700 nm was 4.0.

2. Production of polarizer (2)

Except that the polyvinyl alcohol film with a thickness of 30 μm (average degree of polymerization is about 2400, saponification degree above 99.9 mol%) is used instead of the polyvinyl alcohol film with a thickness of 60 μm, the polarizer (1) is obtained in the same way as the polarizer (1). A polarizer (2) with a thickness of 12 μm is adsorbed on the film and aligned with iodine. The absorbance A ₇₀₀ of the polarizer (2) at a wavelength of 700 nm was 4.0.

3. Production of polarizer (3)

Except that the polyvinyl alcohol film with a thickness of 75 μm (average degree of polymerization is about 2400, saponification degree above 99.9 mol%) is used instead of the polyvinyl alcohol film with a thickness of 60 μm, the polyvinyl alcohol film obtained in the same way as the polarizer (1) A polarizer (3) with a thickness of 28 μm is adsorbed on the film and aligned with iodine. The absorbance A ₇₀₀ of the polarizer (3) at a wavelength of 700 nm was 4.0.

4. Production of polarizer (4)

A polarizer (4) with a thickness of 12 μm in which iodine was adsorbed and aligned on a polyvinyl alcohol film was obtained in the same manner as in “Preparation of polarizer (2)” except that the temperature of pure water during washing was changed to 21°C. The absorbance A ₇₀₀ of the polarizer (4) at a wavelength of 700 nm is 3.3.

5. Production of polarizer (5)

A polarizer (5) with a thickness of 12 μm in which iodine was adsorbed and aligned on a polyvinyl alcohol film was obtained in the same manner as in “Preparation of polarizer (2)” except that the temperature of pure water during washing was changed to 34°C. The absorbance A ₇₀₀ of the polarizer (5) at a wavelength of 700 nm was 4.7.

6. Preparation of water-based adhesive

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 solution of polyvinyl alcohol. Next, 1.5 parts by mass of a water-soluble polyamide polyamine epoxy resin ["Sumirez Resin 650 (30)" manufactured by Taoka Chemical Industry Co., Ltd., solid content concentration: 30% by mass]] was added to 100 parts by mass of water in the solution. By mixing with this aqueous solution, a water-based adhesive agent is obtained.

7. Preparation of ultraviolet (active energy ray) hardening adhesive

Mix 80 parts of the following alicyclic epoxy resin (a1) and 20 parts of aliphatic epoxy resin (a2) as hardening components, and further add and mix 4.5 parts of photocationic polymerization initiator as solid components to prepare ultraviolet curing type then agent.

． Cycloaliphatic epoxy resin (a1): 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate: "cell oxide (registered trademark) 2021P" manufactured by Daicel Chemical Industry Co., Ltd.

． Aliphatic epoxy resin (a2): 1,4-butanediol diglycidyl ether: "Denacol (registered trademark) EX-121" manufactured by Nagase Chemtex Co., Ltd.

． Photocationic polymerization initiator: triaryl permeicium salt-based photocationic polymerization initiator: 50% propylene carbonate solution, "CPI-100P" manufactured by San-Apro Co., Ltd.

[Example 1]

Apply the above-mentioned water-based adhesive on both sides of the polarizer (1), and use a bonding device [manufactured by Fujipla Co., Ltd. "LPA3301"] to pass through the water-based adhesive on one side of the polarizer (1) and bond it as a protective film. A cellulose triacetate film (TAC) ["KC4UA" manufactured by KONICA MINOLTA OPTO Co., Ltd. with a thickness of 40 μm] subjected to corona treatment on the surface, moisture permeability: 830 g/m ² . 24 hours] on the other side of the polarizer (1) through a water-based adhesive and bonded on the bonding surface to a corona-treated unstretched norcamphene-based resin with a thickness of 23 μm [Japan ZEON Co., Ltd. "ZEONOR" , Moisture permeability: 20g/m ² . 24 hours]. Then, after drying at 80 degreeC for 5 minutes, it aged at 40 degreeC and 23%RH for 72 hours. After aging, an acrylic adhesive (P-119E, manufactured by Lintec Co., Ltd.) was applied on the ZEONOR surface using the above laminating device to form a first adhesive layer with a thickness of 20 μm. Also, on the TAC surface side, an acrylic adhesive (P-119E manufactured by Lintec Co., Ltd.) was applied using the bonding apparatus described above to form a second adhesive layer with a thickness of 20 μm. Thereby, an optical layered body (1) was obtained.

At this time, the total thickness of all the adhesive layers in the optical laminate (1) (that is, the total thickness of the first adhesive layer and the second adhesive layer) T1 is 40 μm, the thickness T2 of the polarizer is 23 μm, T2/ T1 is 0.58.

[Example 2]

An optical laminate ( 2 ) was obtained in the same manner as in Example 1 except that a polarizer ( 2 ) was used instead of the polarizer ( 1 ). At this time, the total thickness T1 of all the adhesive layers in the optical laminate (2) (that is, the total thickness of the first adhesive layer and the second adhesive layer) is 40 μm, the thickness T2 of the polarizer is 12 μm, and T2/ T1 is 0.30.

[Example 3]

An optical laminate (3) was obtained in the same manner as in Example 1 except that the thickness of the second adhesive layer was 40 μm. At this time, the optical laminate (3) The total thickness T1 of all the adhesive layers (that is, the total thickness of the first adhesive layer and the second adhesive layer) is 60 μm, the thickness T2 of the polarizer is 23 μm, and T2/T1 is 0.38.

[Example 4]

On one side of a cellulose triacetate film (TAC) with a thickness of 40 μm ["KC4UA" manufactured by KONICA MINOLTA OPTO Co., Ltd.], a UV-curable adhesive is applied with a bar coater so that the film thickness after curing becomes about 2 μm. coating. A polarizer (1) is pasted on the coated surface. Next, corona discharge treatment was performed on one side of the unstretched norcamphene-based resin with a thickness of 23 μm [Japan ZEON Co., Ltd. "ZEONOR"], and the above-mentioned ultraviolet curable adhesive was applied to the corona discharge-treated surface. The agent was applied using a bar coater so that the film thickness after curing became about 2 μm. On the coated surface, a polarizer having the above-mentioned cellulose triacetate film bonded on one side was bonded to the polarizer side to produce a laminate. From the cellulose acetate film side of the laminate, ultraviolet rays were irradiated so that the cumulative light intensity became 250mJ/cm ² using an ultraviolet irradiation device with a belt conveyor [for the lamp system, "D valve" manufactured by fusion UV systems Co., Ltd.]. UV curable adhesive hardens.

Thereafter, an acrylic adhesive (P-119E, manufactured by Lintec Co., Ltd.) was applied to the ZEONOR surface using a laminating device [manufactured by Fujipla Co., Ltd. "LPA3301"] to form a first adhesive layer with a thickness of 20 μm. Moreover, an acrylic adhesive (P-119E, manufactured by Lintec Co., Ltd.) was applied to the TAC surface side using the bonding apparatus described above to form a second adhesive layer with a thickness of 20 μm. Thereby, an optical layered body (4) was obtained.

At this time, the total thickness T1 of all the adhesive layers in the optical laminate (4) (that is, the total thickness of the first adhesive layer and the second adhesive layer) is 40 μm, the thickness T2 of the polarizer is 23 μm, and T2/ T1 is 0.58.

[Example 5]

Apply an acrylic adhesive (P-119E by Lintec Co., Ltd.) to one side of the polarizer (1) using a bonding device ["LPA3301" manufactured by Fujipla Co., Ltd.] to form a first adhesive layer with a thickness of 20 μm. . Also, an acrylic adhesive (P-119E, manufactured by Lintec Co., Ltd.) was applied to the other surface of the polarizer (1) using the above laminating device to form a second adhesive layer with a thickness of 20 μm. Thereby, an optical layered body (5) was obtained.

At this time, the total thickness of all the adhesive layers in the optical laminate (5) (that is, the total thickness of the first adhesive layer and the second adhesive layer) T1 is 40 μm, the thickness T2 of the polarizer is 23 μm, T2/ T1 is 0.58.

[Example 6]

An optical laminate ( 6 ) was obtained in the same manner as in Example 5 except that the polarizer ( 2 ) was used instead of the polarizer ( 1 ). At this time, the total thickness of all the adhesive layers in the optical laminate (6) (that is, the total thickness of the first adhesive layer and the second adhesive layer) T1 is 40 μm, the thickness T2 of the polarizer is 12 μm, T2/ T1 is 0.30.

[Example 7]

In addition to making the thickness of the second adhesive layer 40 μm, and implementing An optical laminate (7) was obtained in the same manner as Example 5. At this time, the total thickness of all the adhesive layers in the optical laminate (7) (that is, the total thickness of the first adhesive layer and the second adhesive layer) T1 is 60 μm, the thickness T2 of the polarizer is 23 μm, T2/ T1 is 0.38.

[Comparative example 1]

An optical laminate ( 8 ) was obtained in the same manner as in Example 1 except that a polarizer ( 3 ) was used instead of the polarizer ( 1 ). At this time, the total thickness T1 of all adhesive layers in the optical laminate (8) (that is, the total thickness of the first adhesive layer and the second adhesive layer) is 40 μm, and the thickness T2 of the polarizer is 28 μm. T2/ T1 is 0.70.

[Example 8]

An optical laminate ( 9 ) was obtained in the same manner as in Example 1 except that a polarizer ( 4 ) was used instead of the polarizer ( 1 ). At this time, the total thickness of all adhesive layers in the optical laminate (9) (i.e. the total thickness of the first adhesive layer and the second adhesive layer) T1 is 40 μm, the thickness T2 of the polarizer is 12 μm, T2/ T1 is 0.30.

[Example 9]

An optical laminate ( 10 ) was obtained in the same manner as in Example 1 except that a polarizer ( 5 ) was used instead of the polarizer ( 1 ). At this time, the total thickness of all the adhesive layers in the optical laminate (10) (that is, the total thickness of the first adhesive layer and the second adhesive layer) T1 is 40 μm, the thickness T2 of the polarizer is 12 μm, T2/ T1 is 0.30.

[Reference example 1]

An optical layered body (11) was obtained in the same manner as in Comparative Example 1 except that the second adhesive layer was not formed. T1 is 20 μm, the thickness T2 of the polarizer is 28 μm, and T2/T1 is 1.40.

[Evaluation of yellowing (105°C)]

The optical laminates (1) to (10) obtained in Examples 1 to 9 and Comparative Example 1 were cut to a size of 30mm×30mm, and the surfaces of the first adhesive layer and the second adhesive layer were bonded to An alkali-free glass ["EAGLE XG" manufactured by Corning Incorporated] was used to prepare an evaluation sample. Also, the optical laminate (11) obtained in Reference Example 1 was cut into a size of 30mm×30mm, and the surface of the first adhesive layer was bonded to an alkali-free glass ["EAGLE XG" manufactured by Corning Incorporated] to prepare an evaluation sample.

The evaluation sample was autoclaved at a temperature of 50°C and a pressure of 5kg/cm ² (490.3kPa) for 1 hour, and then left for 24 hours in an environment of a temperature of 23°C and a relative humidity of 55%. Thereafter, a heating test was carried out in which the product was stored in a heating environment at a temperature of 105° C. for 100 hours, and the color change before and after heating was visually confirmed. A is for almost no change, B is for a slight color change, C is for a color change that can be confirmed in about half of the polarizer surface, and D is a large color change for almost the entire surface of the polarizer. The obtained results are shown in Table 1.

Also, the evaluation sample containing the optical layered body (11) produced in Reference Example 1 was laminated with non-alkali glass only on one side, so no polyene was produced, so no The color change occurred, and the evaluation result was A.

[Evaluation of yellowing (95°C)]

Evaluation samples were produced using the optical layered bodies (1) to (10) obtained in Examples 1 to 9 and Comparative Example 1 and Reference Example 1 in the same manner as above. The evaluation sample was autoclaved at a temperature of 50°C and a pressure of 5kg/cm ² (490.3kPa) for 1 hour, and then left for 24 hours in an environment of a temperature of 23°C and a relative humidity of 55%. Thereafter, a heating test was carried out in which the product was stored in a heating environment at a temperature of 95° C. for 100 hours, and the color change before and after heating was visually confirmed. A is for almost no change, B is for a slight color change, C is for a color change that can be confirmed in about half of the polarizer surface, and D is a large color change for almost the entire surface of the polarizer. The obtained results are shown in Table 1.

In addition, the evaluation sample containing the optical layered body (11) produced in Reference Example 1 was laminated with non-alkali glass only on one side, so polyene did not occur, so no color change occurred, and the evaluation result was A.

[Red evaluation]

The optical laminates (1) to (10) obtained in Examples 1 to 9 and Comparative Example 1 were cut to a size of 150mm×100mm, and the surfaces of the first adhesive layer and the second adhesive layer were bonded to An alkali-free glass ["EAGLE XG" manufactured by Corning Incorporated] was used to prepare an evaluation sample. Also, the optical laminate (11) obtained in Reference Example 1 was cut into a size of 30mm×30mm, and the surface of the first adhesive layer was bonded to an alkali-free glass ["EAGLE XG" manufactured by Corning Incorporated] to produce Evaluation samples.

Thereafter, a heating test was carried out in which the evaluation sample was stored in a heating environment at a temperature of 105° C. for 30 minutes, and the change in the lack of red color in the state of the crossed polarizers before and after heating was visually confirmed. There is almost no change before and after heating and no redness change is A; after heating, a slight lack of redness can be confirmed as B; after heating, redness can be confirmed as C; after heating, a clear redness can be confirmed as D. The obtained results are shown in Table 1.

The ratio (T2/T1) of the thickness T2 of the polarizer to the total thickness T1 of the first and second adhesive layers is 0.6 or less, and the thickness T2 of the polarizer is 23 μm or less in the optical laminates of Examples 1 to 9, It is not easy to produce yellowing after exposure to high temperature environment. On the other hand, in the optical layered body of Comparative Example 1 in which T2/T1 exceeded 0.6 and T2 exceeded 23 μm, a color change was observed in the yellowing evaluation at 95°C, and further, in the yellowing evaluation at 105°C The color of the polarizing plate changes greatly almost all over the surface, and it is found that it will be significantly yellowed due to exposure to high temperature environments. Also, in the optical layered body of Reference Example 1 in which the second adhesive layer was not provided and only one side of the optical layered body was covered with a glass plate, yellowing did not occur after exposure to a high-temperature environment.

1: Polarizer

2: The first adhesive layer

2': Second adhesive layer

3: Protective film

4: Adhesive layer

5: Protection sheet

6: Transparent board

7: Image display unit

10: polarizer

Claims (4)

An optical laminate comprising a first adhesive layer, a polarizing plate, and a second adhesive layer in sequence; the polarizing plate includes a polarizer with a thickness of 23 μm or less, and the polarizer is polyethylene containing a dichroic pigment Alcohol-based resin film; when the total thickness of all adhesive layers contained in the aforementioned optical laminate is T1 and the thickness of the aforementioned polarizer is T2, T2/T1 is 0.45 or less; the absorbance A ₇₀₀ of the aforementioned polarizer at a wavelength of 700nm is 3.7 or more and 4.5 or less; the thickness of the first adhesive layer is not less than 10 μm and not more than 25 μm, and the thickness of the second adhesive layer is not less than 30 μm and not more than 250 μm; It is pasted on the image display unit, and is used by the way of pasting the second adhesive layer on the transparent plate. The optical laminate described in claim 1 of the patent application is used by sticking the adhesive layer between the transparent plate and the image display unit. The optical laminate as described in claim 1 or 2 of the patent claims, wherein the polarizer includes a protective film laminated on at least one side of the polarizer, and the protective film has a weight of 200g/m ² . More than 24 hours of moisture permeability. An image display device comprising the optical laminate as described in any one of items 1 to 3 of the patent application.

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