TWI805553B - Optical laminate - Google Patents

Abstract

Provide is an optical laminate which is hardly yellowed over time and is excellent in yellowing suppression effect even when exposed to high temperature environment.

An optical laminate comprises a first adhesive layer, a polarizing plate, and a second adhesive layer in this order, The polarizing plate comprises a polarizer and a protective film laminated on at least one surface of the polarizer via an active energy ray curable adhesive layer, wherein the polarizer is a polyvinyl alcoholic resin film containing a dichroic dye, When the total thickness of all the pressure-sensitive adhesive layers contained in the optical laminate 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 including the optical laminate. Specifically, it relates to an optical layered body used by bonding between a transparent plate and an image display unit via an adhesive layer, and an image display device including the above-mentioned optical layered body.

In the past, optical laminates such as polarizing plates or elliptical polarizing plates were bonded between image display units such as liquid crystal units or organic EL elements, and transparent plates (front panels) through an adhesive layer, and were used in liquid crystal displays. Various image display devices such as devices or organic EL display devices. In recent years, such image display devices, in addition to portable devices such as mobile phones and tablet terminals, can also be used as image display devices for vehicles such as car navigation devices and backup monitors. extremely broad. Accompanied by this, for optical laminates, high durability is required in a more severe environment (for example, high temperature environment) than conventional ones, and thus a polarizing plate for the purpose of ensuring the durability has been proposed (Patent Literature 1).

[Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2014-102353

An image display device in which an optical laminate using a polyvinyl alcohol-based resin film containing a dichroic pigment as a polarizer is bonded between an image display unit and a transparent plate via an adhesive layer, when exposed to a high temperature environment , due to the progress of polyvinyl alcohol, the optical laminate may have the problem of yellowing. This yellowing becomes an appearance defect of the optical layered body, and the progress of the yellowing causes defects in the optical characteristics of the optical layered body. Especially in a severe temperature environment exceeding 95°C (such as 105°C, etc.), the progress of yellowing tends to become more significant, so an optical laminate with a high inhibitory effect on yellowing in such high-temperature environments is required body.

Therefore, the object of the present invention is to provide an optical laminate that is less prone to yellowing over time and has an excellent yellowing inhibition effect even when exposed to a high temperature environment.

The inventors of the present invention earnestly studied to solve the above-mentioned problems, and completed the present invention.

That is, the present invention provides the following preferred aspects [1] to [7].

[1] An optical laminate comprising a first adhesive layer, a polarizing plate, and a second adhesive layer in this order, wherein the polarizing plate includes: a polarizer, and an active energy ray-curable type A protective film laminated with an adhesive agent on at least one surface of the polarizer, the polarizer being a polyvinyl alcohol-based resin film containing a dichroic pigment; and When the total thickness of all the pressure-sensitive adhesive layers included in the optical layered body is T1, and the thickness of the polarizer is T2, T2/T1 is 0.6 or less.

[2] The optical laminate according to [1] above, wherein the polarizer has an absorbance A ₇₀₀ of 5.5 or less at a wavelength of 700 nm.

[3] The optical laminate according to [1] or [2] above, which is used by bonding between the transparent plate and the image display unit via the adhesive layer.

[4] The optical laminate according to any one of [1] to [3] above, wherein the polarizer has a thickness of 30 μm or less.

[5] The optical laminate according to any one of [1] to [4] above, wherein the polarizing plate includes a protective film laminated on both sides of the polarizing plate with an active energy ray-curable adhesive , one side of the protective film is made of cellulose-based polymer.

[6] The optical laminate according to any one of [1] to [5] above, wherein the protective film laminated on at least one of the polarizers has a water vapor transmission rate of 200 g/m ² ‧24 hours or more.

[7] An image display device comprising the optical layered body according to any one of [1] to [6].

According to the present invention, it is possible to provide an optical laminate that is less prone to yellowing over time and has an excellent yellowing suppression effect even 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. The scope of the present invention is not limited to the embodiments described here, and various changes can be made within the range not detracting from the gist of the present invention.

The optical layered body (also referred to as "the optical layered body of the present invention") of one embodiment of the present invention includes a first adhesive layer, a polarizing plate, and a second adhesive layer in this order. According to Fig. 1, the structure of one embodiment of the optical laminate of the present invention is described. The optical laminate of the present invention has a first adhesive layer (2) on one side of the polarizing plate (10). The surface layer of the polarizing plate (10) opposite to the first adhesive layer (2) is formed by a second adhesive layer (2'). In the optical laminated body of the present invention, the surfaces of the first adhesive layer (2) and the second adhesive layer (2') opposite to the polarizing plate (10) can be attached separately in order to protect the adhesive layer. A peelable protective sheet (5). By peeling off the protective sheet (5), and respectively attaching the first adhesive layer (2) to the image display unit (7), attaching the second adhesive layer (2') to the transparent plate (6), An image display device of an embodiment of the present invention (also referred to as "the image display device of the present invention") as shown in FIG. 2 is constituted. In Fig. 2, the backlight and the like are omitted.

The polarizing plate (10) constituting the optical laminate of the present invention has: on at least one surface of the polarizing plate (1) via an adhesive layer (4) The structure of the protective film (3). In one embodiment of the optical layered body of the present invention, the optical layered body of the present invention is equipped with a protective film (3) via an adhesive layer (4) on both sides of a polarizer (1).

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

[Optical laminate]

In the optical laminate of the present invention, when the total thickness of all the adhesive layers constituting the optical laminate is T1, and the thickness of the polarizer is T2, T2/T1 is 0.6 or less, preferably 0.55 or less, especially preferably It is less than 0.5, most preferably less than 0.45. 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, and is, for example, 0.001 or more, preferably 0.005 or more, particularly preferably 0.008 or more, more preferably 0.01 or more. The so-called "total thickness T1 of all adhesive layers constituting the optical laminate" refers to the thickness of the first adhesive layer and the second adhesive layer, and the sum of the thicknesses of other adhesive layers if present. The so-called "other adhesive layer" refers to an adhesive layer other than the first adhesive layer and the second adhesive layer that may be included in the optical laminate. The adhesive layer of the board, and the adhesive layer that can be used to attach the polarizer and the protective film, etc. When the optical laminate does not contain other adhesive layers, but only includes the first adhesive layer and the second adhesive layer as adhesive layers, the total thickness T1 of all adhesive layers constituting the optical laminate is the first adhesive The sum of the thickness of the layer and the thickness of the second adhesive layer.

In the present invention, controlling the ratio of the thickness of the polarizer to the total thickness of the adhesive layer within a predetermined range is important for obtaining the effect of suppressing yellowing. That is, for example, even if the thickness of the polarizer is the same, if the above-mentioned predetermined ratio is not satisfied in relation to the total thickness of the adhesive layer, 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 above-mentioned predetermined ratio is not satisfied in relation to the thickness of the polarizer, it is difficult to sufficiently suppress yellowing when exposed to a high-temperature environment.

In the optical layered body of the present invention, by controlling the ratio of the thickness of the polarizer to the total thickness of the adhesive layer within the above predetermined range, a high yellowing suppression effect can be easily imparted to the optical layered body. The yellowing of the optical laminate is caused by the polyolefination of polyvinyl alcohol in the polarizer, and the polyolefination tends to be accelerated when the moisture content of the polarizer is high. Therefore, for example, although it is possible to control the moisture content of the polarizing plate in order to suppress polyeneization, it is necessary to perform a drying step to control the moisture content of the polarizing plate. The optical characteristics of the polarizing plate may be reduced when it is carried out under certain conditions. In the present invention, since yellowing can be suppressed by controlling the ratio of the thickness of the polarizer to the total thickness of the adhesive layer within the aforementioned predetermined range, it is not necessary to perform a drying step for adjusting the moisture content of the polarizer, and it is not easy A decrease in the optical characteristics of the polarizing plate occurs. In addition, there is no need to perform a drying step, and it is easy and efficient to produce, etc., and productivity can also be improved. Furthermore, since the yellowing inhibitory effect can be imparted by controlling the thickness of the polarizer and the total thickness of the adhesive layer, the constituents and/or composition of the polarizer or protective film constituting the polarizing plate are not limited. Combination of polarizers and protective films with various configurations. Therefore, readily available materials can be selected Or an inexpensive material is also advantageous from the standpoint of reducing production costs.

In the present invention, when the thickness ratio of the polarizer and the adhesive layer is in the aforementioned predetermined range, although the effect of suppressing the yellowing formed over time can be obtained, when the thickness (T2) of the polarizer is 30 μm or less, Furthermore, a particularly excellent yellowing suppression effect can be obtained. The thickness of the polarizer constituting the optical laminate of the present invention is preferably at most 30 μm, more preferably at most 28 μm, and more preferably at most 25 μm. The lower limit of the thickness of the polarizer is not particularly limited, but is usually 3 μm or more. When the thickness of the polarizer is 30 μm or less and T2/T1 is in the range of 0.6 or less in relation to the total thickness of the adhesive layer, the optical laminate of the present invention can obtain particularly excellent yellowing suppression effect. In addition, since the thickness of the required adhesive layer is also reduced by reducing the thickness of the polarizer, it is also advantageous from the viewpoint of thinning the optical layered body.

[polarizer]

The polarizing plate constituting the optical laminate of the present invention has a protective film on at least one surface of the polarizing plate via an active energy ray-curable adhesive layer.

〈Polarizer〉

Polarizer refers to a film that has the function of extracting linearly polarized light from incident natural light, and is a polyvinyl alcohol-based resin film containing dichroic pigments. As the polyvinyl alcohol-based resin constituting the polyvinyl alcohol-based resin film, a saponified product of polyvinyl acetate-based resin can be used. Polyvinyl acetate-based resins include copolymers of vinyl acetate and other monomers that can be copolymerized with vinyl acetate (ethylene-vinyl acetate) in addition to polyvinyl acetate that is a homopolymer of vinyl acetate. copolymers, etc.). Other monomers copolymerizable with vinyl acetate, such as Examples thereof include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having ammonium groups.

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

What formed this polyvinyl-alcohol-type resin into a film can be used as the base material film of a polarizing film. The method of forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a film can be formed by a generally known method. The film thickness of the base material film made of polyvinyl alcohol resin is not particularly limited, but it is, for example, 10 to 150 μm, preferably 15 to 100 μm, more preferably 20 to 80 μm in consideration of easiness of stretching.

Polarizers are generally produced through: the step of uniaxially stretching the polyvinyl alcohol-based resin film, the step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye to absorb the dichroic dye, A step of treating the polyvinyl alcohol-based resin film on which a dichroic dye is adsorbed with an aqueous solution, and a step of washing with water after treating with an aqueous solution of boric acid. The dichroic dye is contained in the polyvinyl alcohol-based resin film by dyeing the polyvinyl alcohol-based resin film with the dichroic dye. When a polarizer is produced by this production method, the polarizer becomes 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 of the dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxially stretched after dyeing, the uniaxially stretched Before treatment or during boric acid treatment. Uniaxial stretching may also be performed in these plural stages. In the case of uniaxial stretching, it may be uniaxially stretched between rolls having different circumferential speeds, or uniaxially stretched using heated rolls. In addition, the uniaxial stretching may be a dry stretching in which stretching is performed in the air, or a wet stretching in which a polyvinyl alcohol-based resin film is stretched in a state in which the polyvinyl alcohol-based resin film is swollen using a solvent. The draw ratio is preferably at most 8 times, particularly preferably at most 7.5 times, and more preferably at most 7 times, from the viewpoint of suppressing deformation of the polarizer. In addition, the draw ratio is usually 4.5 times or more from the viewpoint of expressing the function as a polarizer. By setting the draw ratio in the above-mentioned range, the deformation of the polarizer over time can be suppressed.

As a method of dyeing a polyvinyl alcohol-type resin film with a dichroic dye, 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. Dichroic dyes include, for example, dichroic direct dyes composed of diazo compounds such as C.I.DIRECT RED 39, and dichroic direct dyes composed of compounds such as trisazo and tetrasazo. The polyvinyl alcohol-based resin film is preferably preliminarily dipped in water before dyeing.

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

Before immersing the polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide, the film may be immersed in water in order to swell and facilitate dyeing. The temperature of the immersion treatment is usually 20 to 80°C, preferably 30 to 60°C, and the immersion time (dyeing time) is usually 20 to 1800 seconds.

When a dichroic dye is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye for dyeing is generally employed. The content of the dichroic dye in the aqueous solution is usually about 1×10 ^-4 to 10 parts by mass per 100 parts by mass of water, preferably about 1×10 ^-3 to 1 part by mass, especially about 1× 10 ^-3 to 1×10 ^-2 parts by mass. The aqueous solution may also contain inorganic salts such as sodium sulfate as a dyeing auxiliary. 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 dyeing with dichroic dyes can usually be carried out by immersing the dyed polyvinyl alcohol-based resin film in a boric acid aqueous solution. The amount of boric acid in the boric acid aqueous solution is usually about 2 to 15 parts by mass, preferably about 5 to 12 parts by mass, per 100 parts by mass of water. When using iodine as a dichroic dye, the boric acid aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid aqueous solution is usually about 0.1 to 15 parts by mass, preferably about 5 to 12 parts by mass, per 100 parts by mass of water. The immersion time in the boric acid aqueous solution is usually 60 to 1200 seconds, preferably 150 to 600 seconds, especially preferably 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually above 50°C, preferably from 50 to 85°C, especially preferably from 60 to 80°C.

The polyvinyl alcohol-based resin film after boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing the 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, it is dried to obtain a polarizer. The drying treatment can be performed using, for example, a hot air dryer or a far-infrared heater. The temperature of the drying treatment is usually 30 to 100°C, preferably 40 to 95°C, especially preferably 50 to 90°C. The drying time is generally 40 to 600 seconds, preferably 50 to 600 seconds, and especially preferably 60 to 600 seconds.

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

The absorbance A ₇₀₀ of the thus obtained polarizer at a wavelength of 700 nm is preferably 5.5 or less, particularly preferably 5.0 or less, more preferably 4.5 or less, and most preferably 4.2 or less. The absorbance A ₇₀₀ is related to the content of the I ₅ complex in the polarizer. When the I ₅ complex is too much, I ₃ ^- or I ^- iodide ions will be generated from the I ₅ complex in the durability test. will promote the polyenylation reaction. In addition, the absorbance A ₇₀₀ may be greater than 3.0, preferably greater than 3.5, more preferably greater than 3.7. When the absorbance A ₇₀₀ is too low, the I ₅ complex is lost in the durability test and the relative amount is reduced, so the absorption around the wavelength of 700nm is insufficient, and the polarizer sometimes turns red. The absorbance A ₇₀₀ of the polarizer can be controlled, for example, by adjusting the temperature of the water in the washing process when manufacturing the polarizer.

The absorbance A ₇₀₀ of the polarizing plate can be measured using an absorbance meter such as an ultraviolet-visible spectrophotometer, and calculated from the following formula.

A ₇₀₀ =-log[{TD transmittance at a wavelength of 700nm (%)}/100] is measured using polarized light parallel to the absorption axis direction of the polarizer as incident light. In this formula, the so-called "TD transmittance" refers to the transmittance when the direction of the polarized light emitted from the Glan-Thompson (Glan-Thompson) filter is perpendicular to the transmission axis of the polarizer. For example, it can be measured using a spectrophotometer with an integrating sphere V7100 manufactured by JASCO Corporation.

<Protective film>

The polarizing plate constituting the optical laminate of the present invention has a structure in which a protective film (especially a transparent protective film) is layered on at least one area of the polarizing plate. The protective film, because it is beneficial to prevent the shrinkage and expansion of the polarizer, and prevent the deterioration of the polarizer caused by temperature, humidity, ultraviolet rays, etc., is preferably on both sides of the polarizer in the optical laminate of the present invention. The laminate has a protective film.

The material constituting the protective film is preferably excellent in transparency, mechanical strength, thermal stability, and isotropy. Examples include polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose-based polymers such as cellulose diacetate and cellulose triacetate, polymethyl methacrylate, etc. Acrylic polymers such as esters, styrene polymers such as polystyrene or acrylonitrile-styrene copolymer (AS resin), polycarbonate polymers. In addition, polyolefin-based polymers such as polyethylene, polypropylene, and ethylene-propylene copolymers, cyclic olefin-based polymers with a norbornene structure, vinyl chloride-based polymers, nylon or aromatic polyamides Amide-based polymers such as amines, imide-based polymers, sulfide-based polymers, polyether-sulfide-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, Vinylidene chloride-based polymers, vinyl butyral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, or blends of the aforementioned polymers, etc. Examples of polymers for protective films. The protective film can also be formed as a hardened layer made of acrylic, urethane, acrylic urethane, epoxy, polysiloxane and other thermosetting or ultraviolet curing resins. Among them, those having a hydroxyl group reactive with an isocyanate-based 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, particularly preferably 5 to 200 μm, and more preferably 10 to 100 μm. In addition, the protective film can also have an optical compensation function.

The surface of the protective film that is not adjacent to the polarizer may have a surface treatment layer, such as a hard coat layer or an anti-reflection layer, an anti-stacking layer, or an optical layer such as 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 hard coat layer is for the purpose of preventing damage to the surface of the polarizing plate. For example, a hardened film formed of acrylic, polysiloxane, etc. UV-curable resins, which has excellent hardness and smoothness, can be added to the protective film. The way the surface is formed. The anti-reflection layer is intended to prevent the reflection of external light on the surface of the polarizing plate, and can be achieved by forming an anti-reflection film or the like that has been followed in the past. In addition, the purpose of the anti-stacking layer is to prevent adhesion with adjacent layers.

In addition, the anti-glare layer is for the purpose of preventing external light from reflecting on the surface of the polarizer and hindering the viewing of the light transmitted by the polarizer. For example, it can be formed by imparting a fine uneven structure on the surface of the protective film by sandblasting or embossing roughening, or by preparing transparent particles. Particles used to form the above-mentioned micro-concave-convex structure on the surface include, for example, silicon dioxide, aluminum oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide with an average particle diameter of 0.5 to 50 μm. Inorganic microparticles that may have conductivity; transparent microparticles such as organic microparticles composed of cross-linked or non-cross-linked polymers. When forming the fine uneven structure on the surface, the content of the 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 light transmitted through the polarizer to expand the viewing angle (viewing angle expansion function, etc.).

The aforementioned anti-reflection layer, anti-stacking layer, diffusion layer or anti-glare layer, etc., besides being provided on the protective film and integrated, can also be provided separately from the protective film as another 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 laminated on at least one of the polarizers preferably has a resistance of 200 g/m ² ‧24 hours or more, more preferably 400 g/m ² ‧24 hours or more, more preferably 600 g/m ² ‧24 hours above moisture permeability. When the protective film whose moisture permeability is above the above-mentioned lower limit exists on at least one side of the polarizer, the yellowing of the optical laminate of the present invention over time can be more effectively suppressed, and the two sides of the polarizer can be more effectively suppressed. It is more preferable that there exists a protective film which has a moisture permeability of more than the said lower limit. The moisture permeability of the protective film is usually below 2000g/m ² ‧24 hours. In the present invention, the moisture permeability refers to a value measured at a temperature of 40° C. and a relative humidity of 90% in accordance with JIS Z0208:1976.

<Adhesive layer>

In the optical laminate of the present invention, the polarizer and the protective film are bonded via an active energy ray-curable adhesive layer. In the case of a double-layer protective film of a polarizer, it is preferable that any protective film is bonded through an active energy ray-curable adhesive layer. Here, in the present invention, the term "active energy ray-curable adhesive layer" means a layer composed of a hardened product of an active energy ray-curable adhesive, and the term "active energy ray-curable adhesive" means Adhesive that is hardened by irradiating active energy rays. In the present invention, when the polarizer has a protective film on both sides of the polarizer, the adhesive applied to one side of the polarizer and the adhesive applied to the other side of the polarizer can be the same or different.

Conventionally, in most optical laminates, an aqueous adhesive containing polyvinyl alcohol-based resin or urethane resin as a main component has been used as an adhesive for bonding a polarizer and a protective film. The optical laminate of the present invention can effectively suppress yellowing of the optical laminate by using an active energy ray-curable adhesive as the adhesive for bonding the polarizer and the protective film. For example, by using an active energy ray-curable adhesive to bond the polarizer and the protective film, even at high temperatures (such as 105°C, etc.) where yellowing tends to cause a significant difference, high yellowing inhibition can be maintained Effect. In addition, for example, in an optical layered body including a polarizing plate having the same thickness as a polarizer, in order to obtain the same The thickness of the adhesive layer required for a certain degree of yellowing inhibition effect is relatively small. That is, by using an active energy ray-curable adhesive, the thickness of the adhesive layer laminated on the polarizing plate can be reduced, which is advantageous from the viewpoint of thinning the optical layered body. In addition, by using an active energy ray-curable adhesive, a substantially solvent-free adhesive can be formed, so the step of drying the adhesive layer is not required, and productivity can be improved.

When active energy ray-curable adhesives are classified by their curing methods, cationic polymerizable adhesives containing cationic polymerizable compounds as curable compounds, radical polymerizable adhesives containing radically polymerizable compounds as curable compounds, etc. Adhesives, hybrid curable adhesives containing both cationic polymerizable compounds and radical polymerizable compounds, etc. Specific examples of the cationically polymerizable compound include epoxy compounds having one or more epoxy groups in the molecule, oxetane compounds and vinyl compounds having one or more oxetane rings in the molecule. Moreover, specific examples of the radically polymerizable compound include (meth)acrylic compounds and vinyl compounds having one or more (meth)acryloyl groups in the molecule. The active energy ray-curable adhesive may contain one or more cation polymerizable compounds, and/or one or more radical polymerizable compounds.

cationic polymer adhesive

The cationic polymerizable compound that is the main component of the cationic polymer adhesive refers to a compound or an oligomer that undergoes cationic polymerization and hardens by irradiation or heating of active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. substances, epoxy compounds, oxygen compounds, ethylene compounds can be exemplified compounds etc. Among them, preferred cationically polymerizable compounds are epoxy compounds.

The epoxy compound is a compound having one or more, preferably two or more epoxy groups in the molecule. Epoxy compounds may be used alone or in combination of two or more. Examples of epoxy compounds include alicyclic epoxy compounds, aromatic epoxy compounds, hydrogenated epoxy compounds, and aliphatic epoxy compounds. Among them, the epoxy compound preferably contains an alicyclic epoxy compound or an aliphatic epoxy compound, and particularly preferably contains an alicyclic epoxy compound, from the viewpoints of weather resistance, curing speed, and adhesiveness.

The alicyclic epoxy compound is a compound having one or more epoxy groups bonded to an alicyclic ring in the molecule. The "epoxy group bonded to an alicyclic ring" means a bridging oxygen atom -O- in the structure represented by the following formula (I). In the following formula (I), m is an integer of 2 to 5.

In (CH ₂ ) _m of the above formula (I), a compound in which one or more groups in the form of hydrogen atoms are removed and bonded to other chemical structures may be an alicyclic epoxy compound. One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group.

Among them, the cycloaliphatic epoxy compound with epoxycyclopentane [m=3 in the above-mentioned formula (I)] or epoxycyclohexane [m=4 in the above-mentioned formula (I)] is beneficial to improve The storage elastic modulus of the adhesive layer is also advantageous in terms of adhesion between the polarizer and the protective film. The alicyclic Specific examples of formula epoxy compounds. Here, the compound names are listed first, and then the corresponding chemical formulas are displayed, and the same symbols are attached to the compound names and the corresponding chemical formulas.

A: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, B: 3,4-epoxycyclohexyl 3,4-epoxy-6-methylcyclohexanecarboxylate Base-6-methylcyclohexylmethyl ester, C: bis(3,4-epoxycyclohexanecarboxylate) ethylidene ester, D: adipate bis(3,4-epoxycyclohexylmethyl ) ester, E: bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, F: diethylene glycol bis(3,4-epoxycyclohexylmethyl ether) , G: Ethylene glycol bis(3,4-epoxycyclohexyl methyl ether), H: 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro [5.2.2.5.2.2] Eicosane, I: 3-(3,4-Epoxycyclohexyl)-8,9-epoxy-1,5-dioxaspiro[5.5]undecane , J: 4-vinylcyclohexene dioxide, K: limonene dioxide, L: bis(2,3-epoxycyclopentyl) ether, M: dicyclopentadiene dioxide.

Aromatic epoxy compounds are compounds with aromatic rings and epoxy groups in the molecule. Specific examples thereof include bisphenol-type epoxy compounds such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S, or oligomers thereof; Novolac epoxy resins such as epoxy resins, cresol novolac epoxy resins, and hydroxybenzaldehyde phenolic novolac epoxy resins; glycidyl ethers of 2,2',4,4'-tetrahydroxydiphenylmethane, Polyfunctional epoxy compounds such as glycidyl ether of 2,2',4,4'-tetrahydroxybenzophenone; polyfunctional epoxy resins such as epoxidized polyvinylphenol.

Hydrogenated epoxy compounds are glycidyl ethers of polyols with alicyclic rings, which can selectively hydrogenate the aromatic rings of aromatic polyols in the presence of catalysts and under pressure to obtain nuclear hydrogenated polyols. Hydroxy compounds, and then make this nuclear hydrogenated polyol glycidyl etherification in the system. Specific examples of aromatic polyhydric alcohols include, for example: bisphenol A, Bisphenol-type compounds such as bisphenol F and bisphenol S; phenolic phenolic resins such as phenolic phenolic resins, cresol phenolic resins, and hydroxybenzaldehyde phenolic phenolic resins; tetrahydroxydiphenylmethane, tetrahydroxydiphenylmethane Multifunctional compounds such as ketones and polyvinylphenols. Glycidyl ether can be formed by reacting an alicyclic polyol obtained by hydrogenating the aromatic ring of the aromatic polyol with epichlorohydrin. Among hydrogenated epoxy compounds, glycidyl ether of hydrogenated bisphenol A is preferable.

The aliphatic epoxy compound is a compound having at least one oxirane ring (three-membered cyclic ether) bonded to an aliphatic carbon atom in the molecule. Monofunctional epoxy compounds such as butyl glycidyl ether, 2-ethylhexyl glycidyl ether, etc.; 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl Bifunctional epoxy compounds such as diol diglycidyl ether; trimethylolpropane triglycidyl ether, neopentylthritol tetraglycidyl ether, etc., trifunctional epoxy compounds; 4-vinyl dioxide ring Epoxy compounds such as hexene and limonene dioxide having one epoxy group directly bonded to an alicyclic ring and an oxirane ring bonded to an aliphatic carbon atom, etc. Among them, from the viewpoint of adhesion between the polarizer and the protective film, bifunctional epoxy compounds (also known as epoxy compounds) having two oxirane rings bonded to aliphatic carbon atoms in the molecule are preferred. for aliphatic diepoxides). This preferable aliphatic diepoxy compound can be represented by following formula (II), for example.

Y in the above formula (II) is an alkylene group with 2 to 9 carbon atoms, An alkylene group having 4 to 9 carbon atoms interposed therebetween, or a divalent hydrocarbon group having 6 to 18 carbon atoms having an alicyclic structure.

The aliphatic diepoxy compound represented by the above formula (II), specifically, diglycidyl ether of alkanediol, diglycidyl ether of oligoalkylene glycol with repeating number up to 4, or alicyclic Diglycidyl ethers of diols.

Specific examples of the diol (ethylene glycol) that can form the aliphatic diepoxide represented by the above formula (II) are disclosed below. Alkanediols include ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol , Neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2- Methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol , 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, etc. The oligoalkylene glycols include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and the like. Alicyclic diols include cyclohexanediol, cyclohexanedimethanol, and the like.

Oxygen compounds, one of cationic polymerizable compounds, are compounds containing one or more oxygen and rings (oxygen groups) in the molecule, and specific examples thereof include: 3-ethyl-3-hydroxymethyl oxo group (also 2-Ethylhexyloxyl, 1,4-bis[{(3-ethyloxyl-3-yl)methoxy}methyl]benzene (also known as xylenedioxy and), 3-ethyl-3[{(3-ethyloxy and-3-yl)methoxy}methyl]oxy and, 3-ethyl-3-(phenoxymethyl)oxy and, 3-(cyclohexyloxyloxy)methyl-3-ethyloxyl. Oxygen compounds can be used as the main component of the cationically polymerizable compound, or used in combination with an epoxy compound. By using oxygen and compounds together, the hardening speed and adhesiveness can be improved.

Vinyl compounds that can become cationic polymerizable compounds Compounds, can include aliphatic or alicyclic vinyl ether compounds, such specific examples include: n-pentyl vinyl ether, isopentyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether , 2-ethylhexyl vinyl ether, n-dodecyl vinyl ether, stearyl vinyl ether, octadecyl vinyl ether, etc., the vinyl group of alkyl or alkenyl alcohols with 5 to 20 carbon atoms Ether; 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether and other hydroxyl-containing vinyl ethers; cyclohexyl vinyl ether, 2-methylcyclohexylethylene Vinyl ethers of monoalcohols with aliphatic rings or aromatic rings, such as cyclohexyl methyl vinyl ether, benzyl vinyl ether, etc.; glycerol monovinyl ether, 1,4-butanediol monovinyl ether Ether, 1,4-butanediol divinyl ether, 1,6-hexanediol divinyl ether, neopentyl glycol divinyl ether, neopentyl glycol divinyl ether, neopentyl glycol tetraethylene base ether, trimethylolpropane divinyl ether, trimethylolpropane trivinyl ether, 1,4-dihydroxycyclohexane monovinyl ether, 1,4-dihydroxycyclohexane divinyl ether , 1,4-dihydroxymethylcyclohexane monovinyl ether, 1,4-dihydroxymethylcyclohexane divinyl ether and other polyol mono-to-polyvinyl ethers; diethylene glycol divinyl ether Ether, triethylene glycol divinyl ether, diethylene glycol monobutyl monovinyl ether, polyalkylene glycol mono-to-divinyl ether; glycidyl vinyl ether, ethylene glycol vinyl ether methyl Other vinyl ethers such as acrylates. The vinyl compound can be used as the main component of the cationically polymerizable compound, or it can be used in combination with an epoxy compound, or an epoxy compound and an oxygen compound. By using vinyl compounds in combination, the hardening speed of the adhesive can be increased or the viscosity can be reduced.

Cationic polymer adhesives, which can also include cyclic lactone compounds, cyclic acetal compounds, cyclic thioether compounds, spiro-esterification Other cationic polymerizable compounds other than those mentioned above.

From the point of view of the adhesion between the polarizer and the protective film, when the total amount of the curable compound contained in the cationic polymer adhesive (including the case of the mixed curable adhesive) is 100% by mass, cationic polymer The content of the cationic polymer compound (the content of all the cationic polymerizable compounds contained in the cationic polymerizable adhesive agent, when two or more cationic polymerizable compounds are contained, the total content thereof) is preferably 50% by mass or more, especially Preferably at least 60% by mass, more preferably at least 70% by mass. In addition, the cationic polymer adhesive may further include a polymer component (thermoplastic resin, etc.). Thereby, the storage elastic modulus of the adhesive layer can be reduced, or the adhesion between the polarizer and the protective film can be improved.

When the active energy ray-curable adhesive contains a cationic polymerizable compound, it is preferable to contain a photocationic polymerization initiator. Photocationic polymerization initiators are those that generate cationic substances or Lewis acids by irradiation of active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams to start the polymerization reaction of cation-hardening compounds. Since the photocationic polymerization initiator uses light as a catalyst, it is excellent in storage stability and workability even if it is mixed in a photocation-curable compound. Compounds that generate cationic substances or Lewis acids by irradiation with active energy rays include, for example, onium salts of aromatic iodonium salts or aromatic permeic acid salts, aromatic diazonium salts, and iron-arene complexes.

The aromatic iodonium salt is a compound having a diaryliodonium cation, and the cation typically includes a diphenyliodonium cation. Aromatic cobaltium salts are compounds having a triarylcobaltium cation, the cation, Typical examples include triphenylcobaldium cation, 4,4'-bis(diphenylcobalzyl)diphenylsulfide cation, and the like. The aromatic diazonium salt is a compound having a diazonium cation, and the cation typically includes a benzenediazonium cation. In addition, the iron-arene complex is typically a cyclopentadienyl iron (II) arene cation complex salt.

The cations shown above are paired with anions (anions) to form photocationic polymerization initiators. Examples of anions that constitute photocationic polymerization initiators include special phosphorus anions [(Rf) _n PF _6-n ] ^- , hexafluorophosphate anions PF ₆ ^- , hexafluoroantimonate anions SbF ₆ ^- , pentafluoroanions Fluorohydroxyantimonate anion SbF ₅ (OH) ^- , hexafluoroarsenate anion AsF ₆ ^- , tetrafluoroborate anion BF ₄ ^- , tetrakis(pentafluorophenyl) borate anion B(C ₆ F ₅ ) ₄ ^- etc. . Among them, special phosphorus-based anions [(Rf) _n PF _6-n ] ^- , hexafluorophosphate anions PF ₆ ^- .

These photocationic polymerization initiators may be used alone or in combination of two or more. Among them, aromatic cobaltium salts have ultraviolet absorption properties even in the wavelength region around 300 nm, so they are excellent in curability and can provide cured products with good mechanical strength and adhesive strength, so they can be preferably used.

The amount of the photocationic polymerization initiator in the active energy ray-curable adhesive is generally 0.5 to 10 parts by mass, preferably 6 parts by mass or less, relative to 100 parts by mass of the cationically polymerizable compound. By mixing the photocationic polymerization initiator in an amount of 0.5 parts by mass or more, the cationically polymerizable compound can be sufficiently hardened, and high Mechanical strength and bonding strength. On the other hand, if the amount is too large, the ionic substances in the cured product will increase and the hygroscopicity of the cured product will increase, which may result in a decrease in the durability of the polarizing plate.

As mentioned above, in addition to a cationic polymerizable compound, the cationic polymerizable adhesive agent can also comprise a mixed type adhesive agent by containing a radical polymerizable compound. By using the radically polymerizable compound together, the effect of improving the hardness and mechanical strength of the adhesive layer can be expected, and the viscosity, the curing speed, etc. of the adhesive can be adjusted more easily.

Free Radical Polymerization Adhesive

A radically polymerizable compound that is the main component of a radically polymerizable adhesive refers to a compound that undergoes radical polymerization and hardens by irradiation or heating of active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. Or an oligomer, specifically, a compound having an ethylenically unsaturated bond is exemplified. Compounds having ethylenically unsaturated bonds include styrene, styrenesulfonic acid, and vinyl acetate, in addition to (meth)acrylic compounds having one or more (meth)acryl groups in the molecule. , vinyl propionate, N-vinyl-2-pyrrolidone vinyl compounds, etc. Among them, preferable radical polymerizable compounds are (meth)acrylic compounds.

Examples of (meth)acrylic compounds include (meth)acrylate monomers having at least one (meth)acryloxy group in the molecule, (meth)acrylamide monomers, and 2 A (meth)acryl group-containing compound such as a (meth)acrylic oligomer having at least 2 (meth)acryl groups in the molecule obtained by reacting more than one functional group-containing compound. (Meth)acrylic oligomers, preferably with at least 2 (meth) Acryloxy (meth)acrylate oligomer. The (meth)acrylic compound may be used alone or in combination of two or more.

Examples of (meth)acrylate monomers include monofunctional (meth)acrylate monomers having one (meth)acryloxy group in the molecule, and two (meth)acrylic monomers in the molecule. A bifunctional (meth)acrylate monomer having an acyloxy group, and a polyfunctional (meth)acrylate monomer having three or more (meth)acryloxy groups in the molecule.

Examples of monofunctional (meth)acrylate monomers include alkyl (meth)acrylates. In the alkyl (meth)acrylate, if the alkyl group has 3 or more carbon atoms, it may be linear or branched. Specific examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, ( Isobutyl methacrylate, tertiary butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. In addition, aralkyl (meth)acrylates such as benzyl (meth)acrylates; (meth)acrylates of terpene alcohols such as isobornyl (meth)acrylates; tetrahydrofuran (meth)acrylates Methyl esters (meth)acrylates with tetrahydrofuryl methyl structure; such as cyclohexyl (meth)acrylate, cyclohexylmethyl methacrylate, dicyclopentyl acrylate, dicyclopentene (meth)acrylate (meth)acrylic acid esters, 1,4-cyclohexanedimethanol monoacrylates with cycloalkyl groups in the alkyl position; such as N,N-dimethylaminoethyl (meth)acrylates Amino alkyl (meth)acrylate; such as 2-phenoxyethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, ( The (meth)acrylic acid esters of phenoxypolyethylene glycol methacrylic acid esters having an ether bond at the alkyl portion can also be used as monofunctional (meth)acrylic ester monomers.

Moreover, the monofunctional (meth)acrylate which has a hydroxyl group in an alkyl part, or the monofunctional (meth)acrylate which has a carboxyl group in an alkyl part can also be used. Specific examples of monofunctional (meth)acrylates having a hydroxyl group at the alkyl position include: 2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, (methyl) 4-Hydroxybutyl acrylate, 2-Hydroxy-3-phenoxypropyl (meth)acrylate, Trimethylolpropane mono(meth)acrylate, Neopentylthritol mono(meth)acrylate. Specific examples of monofunctional (meth)acrylates having a carboxyl group at the alkyl position include: 2-carboxyethyl (meth)acrylate, mono(meth)acrylate ω-carboxy-polycaprolactone (n≒2 ), 1-[2-(meth)acryloxyethyl]phthalic acid, 1-[2-(meth)acryloxyethyl]hexahydrophthalic acid, 1-[2 -(meth)acryloxyethyl]succinic acid, 4-[2-(meth)acryloxyethyl]trimellitic acid, N-(meth)acryloxy-N', N'-dicarboxymethyl-p-phenylenediamine.

The (meth)acrylamide monomer is preferably (meth)acrylamide having a substituent at the N-position. A typical example of the substituent at the N-position is an alkyl group, but it can also be combined with (methyl) ) nitrogen atoms of acrylamide together form a ring, and this ring, in addition to carbon atoms and nitrogen atoms of (meth)acrylamide, may also have an oxygen atom as a ring constituent member. Furthermore, the carbon atom constituting the ring may be bonded to a substituent such as an alkyl group or a pendant oxygen (=O).

Specific examples of N-substituted (meth)acrylamide include N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide Amide, N-n-butyl (meth)acrylamide, N-tertiary butyl (meth)acrylamide, N-alkyl (meth)acrylamide of N-hexyl (meth)acrylamide Amide; N,N-Dimethyl(meth)acrylamide, N,N-Diethyl(meth)propylene N,N-dialkyl(meth)acrylamides of amides. In addition, the N-substituent can be an alkyl group with a hydroxyl group, such as N-methylol (meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, N- (2-Hydroxypropyl)(meth)acrylamide, etc. Furthermore, specific examples of N-substituted (meth)acrylamides forming the above-mentioned 5-membered ring or 6-membered ring include N-acrylylpyrrolidine, 3-acrylyl-2-oxazolinone, 4-acrylmorpholine, N-acrylpiperidine, N-methacrylpiperidine, etc.

Bifunctional (meth)acrylate monomers, such as di(meth)acrylate alkylene glycol ester, di(meth)acrylate polyoxyalkylene glycol ester, di(meth)acrylate halogen substituted alkyl Glycol esters, di(meth)acrylates of aliphatic polyols, di(meth)acrylates of hydrogenated dicyclopentadiene or tricyclodecanediolkane, dioxanediol or dioxanediol Di(meth)acrylate of alkanol, di(meth)acrylate of alkylene oxide adduct of bisphenol A or bisphenol F, epoxy di(meth)acrylate of bisphenol A or bisphenol F Esters etc.

More specific examples of bifunctional (meth)acrylate monomers include ethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, di(methyl) 1,4-butylene glycol acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate ester, trimethylolpropane di(meth)acrylate, neopentylthritol di(meth)acrylate, di-trimethylolpropane di(meth)acrylate, diethyl di(meth)acrylate Glycol ester, Triethylene glycol di(meth)acrylate, Dipropylene glycol di(meth)acrylate, Tripropylene glycol di(meth)acrylate, Polyethylene glycol di(meth)acrylate, Di(meth)acrylate Polypropylene glycol methacrylate, Polytetramethylene glycol di(meth)acrylate, Di(meth)acrylate Polysiloxane, di(meth)acrylate of neopentyl glycol hydroxytrimethylacetate; 2,2-bis[4-(meth)acryloxyethoxyethoxyphenyl]propane , 2,2-bis[4-(meth)acryloxyethoxyethoxycyclohexyl]propane, hydrogenated dicyclopentadienyl di(meth)acrylate, tricyclodi(meth)acrylate Decane dimethanol ester, 1,3-dioxane-2,5-diyl di(meth)acrylate [alias: dioxanediol di(meth)acrylate], hydroxypivalaldehyde and tris Acetal compound of hydroxymethylpropane [chemical name: 2-(2-hydroxy-1,1-dimethylethyl)-5-ethyl-5-hydroxymethyl-1,3-dioxane] Di(meth)acrylate, tri(hydroxyethyl)isocyanuric acid di(meth)acrylate, etc.

Polyfunctional (meth)acrylate monomers with more than 3 functions, representative ones are glycerol tri(meth)acrylate, alkoxylated glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate ester, di-trimethylolpropane tri(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, neopentylthritol tri(meth)acrylate, tetra(meth)acrylic acid Neopentylthritol ester, dipentyl tetra(meth)acrylate, dipentyl penta(meth)acrylate, dipentyl hexa(meth)acrylate, etc., which have more than three functions Poly(meth)acrylates of aliphatic polyols, others include poly(meth)acrylates of trifunctional or higher polyols substituted with halogen, tri(meth)acrylic acid of alkylene oxide adducts of glycerin ester, tri(meth)acrylate of alkylene oxide adduct of trimethylolpropane, 1,1,1-tris[(meth)acryloxyethoxyethoxy]propane, tri( Hydroxyethyl) isocyanuric acid tri(meth)acrylate, etc.

On the other hand, (meth)acrylic oligomers include (meth)acrylate urethane oligomers, polyester (meth)acrylic oligomers, Epoxy (meth)acrylic oligomer, etc.

Urethane oligomer (meth)acrylate is a compound having urethane bond (-NHCOO-) and at least two (meth)acryl groups in the molecule. Specifically, it can be: a hydroxyl-containing (meth)acrylic monomer having at least one (meth)acryl group and at least one hydroxyl group in the molecule, and a urethane reaction product with polyisocyanate ; or a urethane compound containing an isocyanate group at the end obtained by reacting a polyol with a polyisocyanate, and a (methyl) compound having at least one (meth)acryl group and at least one hydroxyl group in the molecule ) Urethane reaction products of acrylic monomers, etc.

The hydroxyl-containing (meth)acrylic monomer used in the above-mentioned urethane reaction can be, for example, a hydroxyl-containing (meth)acrylate monomer, and its specific example includes: (meth)acrylic acid 2-hydroxyl Ethyl ester, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, glyceryl di(meth)acrylate , trimethylolpropyl di(meth)acrylate, neopentylthritol tri(meth)acrylate, dipentylthritol penta(meth)acrylate. Specific examples other than hydroxyl-containing (meth)acrylate monomers include N-hydroxyalkyl ( Meth)acrylamide monomer.

Provides polyisocyanate for urethane reaction with hydroxyl-containing (meth)acrylic monomers, such as hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate Isocyanate, toluene diisocyanate, xylene diisocyanate, hydrogenation of aromatic isocyanate in these diisocyanates Diisocyanates (such as hydrogenated toluene diisocyanate, hydrogenated xylene diisocyanate, etc.), di- or tri-isocyanates of triphenylmethane triisocyanate, dibenzylbenzene triisocyanate, etc., and polymerizing the above-mentioned diisocyanates The resulting polyisocyanate and the like.

In addition, as the polyol used to form the urethane compound having an isocyanate group at the terminal by reacting with polyisocyanate, besides aromatic, aliphatic or alicyclic polyol, polyester can also be used. Polyols, polyether polyols, etc. Aliphatic and alicyclic polyhydric alcohols include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, Trimethylolethane, trimethylolpropane, di-trimethylolpropane, neopentylthritol, dipenteoerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylol Butyric acid, glycerin, hydrogenated bisphenol A, etc.

Polyester polyol is obtained by the dehydration condensation reaction of the above-mentioned polyol with polycarboxylic acid or its anhydride. Examples of polycarboxylic acids or their anhydrides, when adding "(anhydride)" to those that can become anhydrides, include succinic acid (anhydride), adipic acid (anhydride), maleic acid (anhydride), Icon Acid (anhydride), trimellitic acid (anhydride), pyromelteric acid (anhydride), phthalic acid (anhydride), isophthalic acid, terephthalic acid, hexahydrophthalic acid (anhydride), etc.

The polyether polyol may be a polyoxyalkylene-modified polyol obtained by reacting the above-mentioned polyol or dihydroxybenzene with an alkylene oxide, in addition to polyalkylene glycol.

Polyester (meth)acrylic oligomers are compounds with ester bonds and at least two (meth)acryl groups (typically (meth)acryloxy groups) in the molecule. Specifically, (meth)acrylic acid, polycarboxylic acid It can be obtained by dehydration condensation reaction of its anhydride and polyhydric alcohol. Examples of polycarboxylic acids or their anhydrides used in the dehydration condensation reaction are succinic acid (anhydride), adipic acid, and maleic acid (anhydride) when adding "(anhydride)" to those that can become anhydrides. , itaconic acid (anhydride), trimellitic acid (anhydride), pyromelite acid (anhydride), hexahydrophthalic acid (anhydride), phthalic acid (anhydride), isophthalic acid, terephthalic acid formic acid etc. In addition, examples of polyols used in the dehydration condensation reaction include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and neopentyl glycol , trimethylolethane, trimethylolpropane, di-trimethylolpropane, neopentylthritol, dipenteoerythritol, dimethylolheptane, dimethylol propionic acid, dimethylol Butyric acid, glycerin, hydrogenated bisphenol A, etc.

The epoxy (meth)acrylic oligomer can be obtained, for example, by addition reaction of polyglycidyl ether and (meth)acrylic acid, and has at least 2 (meth)acryloxy groups in the molecule. The polyglycidyl ether used in the addition reaction includes ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A diglycidyl ether etc.

When the active energy ray-curable adhesive contains a radical polymerizable compound, it is preferable to contain a photoradical polymerization initiator. A photoradical polymerization initiator is one that initiates a polymerization reaction of a radical hardening compound by irradiation of visible light, ultraviolet rays, X-rays, or active energy rays such as electron beams. The photoradical polymerization initiator may be used alone or in combination of two or more.

Specific examples of photoradical polymerization initiators include: acetophenone, 3-methylacetophenone, benzyl dimethyl acetal, 1-(4-isopropylphenyl)-2- Hydroxy-2-methylpropan-1-one, 2-methyl-1-[4-(methylthio)phenyl-2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1 -Acetophenone-based initiators such as phenylpropan-1-one; diphenylketone-based initiators such as diphenyl ketone, 4-chlorobenzophenone, 4,4'-diaminodiphenylketone, etc. Initiator; benzoin ether-based initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone-based initiators such as 4-isopropylthioxanthone; others include xanthone, fennelone, camphorquinone, Benzaldehyde, anthraquinone.

The compounding quantity of the photoradical polymerization initiator in an active energy ray hardening type adhesive agent is 0.5-20 mass parts normally with respect to 100 mass parts of radical polymerizable compounds, Preferably it is 1-6 mass parts. By mixing 0.5 parts by mass or more of the radical photopolymerization initiator, the radical polymerizable compound can be sufficiently cured, and high mechanical strength and adhesive strength can be imparted to the obtained polarizing plate. On the other hand, when the amount is too large, the durability of the polarizing plate may decrease.

In the present invention, the active energy ray-curable adhesive may contain an organic solvent, for example, in order to adjust the viscosity suitable for the coating method to be used, but it is preferably substantially free of solvent (solvent-free). The term "substantially free" means that unavoidable mixing of solvents is not excluded. When a solvent is contained, the content of the solvent is preferably 10% by mass or less with respect to 100% by mass of the active energy ray-curable adhesive. By making the active energy ray-curable adhesive substantially free of solvents, it is possible to suppress the polyeneization of polyvinyl alcohol constituting the polarizer, and it is also possible to improve the productive.

Active energy ray-curing adhesives, which may contain cationic polymerization accelerators such as oxygen and polyols, photosensitizers, ion traps, etc. Additives for collectors, antioxidants, chain transfer agents, adhesion imparting agents, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, antistatic agents, planarizers, solvents, etc.

In the optical laminate of the present invention, the thickness (after hardening) of the adhesive layer formed by the active energy ray-curable adhesive is usually 0.001 to 10 μm, preferably 0.01 to 5 μm, particularly preferably 0.01 to 3 μm, and more preferably Preferably, it is 0.02 to 2 μm. When the thickness of the adhesive layer is within the aforementioned range, the adhesive force between the polarizer and the protective film can be fully ensured, and the appearance is also good, and it is also beneficial to the thinning of the polarizer. Therefore, for the optical laminate of the present invention Body is better.

In the present invention, the active energy ray-curable adhesive layer can be coated with an active energy ray-curable adhesive on a polarizer or laminated on a protective film of a polarizer, or pasted with an active energy ray that has been previously formed into a film. Curing type adhesive is formed by irradiating active energy rays to harden the adhesive layer. The method of coating the active energy ray-curable adhesive can be a generally known method, for example, a fluid casting method, a wire rod coating method, a gravure coating method, a comma wheel coating method, a knife coating method, Die casting method, dip coating method, spray method, etc. The fluid casting method is a method in which an adhesive is poured into the surface and spread-coated while moving a film as an object to be coated in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two. After the adhesive is applied, the polarizer and the protective film bonded thereto are stacked, and the films are bonded by nipping them with rolls or the like. For lamination of films using rollers, for example: after applying the adhesive, pressurize with a roller etc. to uniformly press and spread; and after applying the adhesive, pass between rollers And the method of pressing and expanding by pressing. In this case, the material of the used roller may be metal or rubber. Moreover, when making a film pass between some rolls and press-expanding, some rolls may be made of the same material or different materials.

As the active energy rays, for example, visible light, ultraviolet rays, infrared rays, X-rays, α-rays, β-rays, γ-rays, and electron beams can be used. In the present invention, it is preferable to use ultraviolet rays. The light source of the active energy ray is not particularly limited, but is preferably an active energy ray having a luminescence distribution below a wavelength of 400 nm, specifically, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, Chemical lamps, black light lamps, microwave excited mercury lamps, metal halide lamps, etc.

The intensity of light irradiation on the active energy ray-curable adhesive can be appropriately determined according to the composition of the active energy ray-curable adhesive, and is not particularly limited. The irradiation intensity in the wavelength region effective for activating the polymerization initiator, Preferably it is 0.1 to 6000mW/cm ² , more preferably 10 to 1000mW/cm ² , more preferably 20 to 500mW/cm ² . When the irradiation intensity is within the aforementioned range, the reaction time can be ensured, and in addition, the yellowing or yellowing of the epoxy resin caused by the heat radiated from the light source and the heat generation of the active energy ray-curable adhesive during curing can be suppressed. Deterioration of polarizers. The light irradiation time of 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 preferable that the product of the above-mentioned irradiation intensity and irradiation time The indicated cumulative light intensity is set so as to be 10 to 10000 mJ/cm ² , preferably 50 to 1000 mJ/cm ² , more preferably 80 to 500 mJ/cm ² . When the integrated light intensity to the active energy ray-curable adhesive falls within the above-mentioned range, the activated species from the polymerization initiator can be sufficiently generated, and the hardening reaction can proceed more reliably. In addition, the irradiation time is not too long and can be maintained. Good productivity.

Curing of active energy ray-curable adhesives by irradiation of active energy rays, for example, without compromising the degree of polarization, transmittance, and hue of polarizers, or the transparency of various films constituting protective films and optical layers It is carried out under the condition that the various functions of the polarizing plate are reduced.

On the bonding surface of the polarizer and the protective film, in order to improve the bonding property, surface treatments such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, and saponification treatment can be appropriately applied. The saponification treatment includes a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

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 light concentrating film. These optical films and optical layers can be bonded to a polarizing plate through an adhesive layer composed of an adhesive described later.

Retardation film is an optical film showing optical anisotropy. Retardation film includes birefringent film obtained by uniaxially or biaxially stretching polymer raw materials, alignment film of liquid crystal polymer, and film Those who support the alignment layer of liquid crystal polymer, etc. Stretching can be performed, for example, by roll stretching, long gap stretching, tenter stretching, tubular stretching, 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, and is generally 10 to 200 μm, preferably 20 to 100 μm.

Examples of polymer materials include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyvinyl Carbonate, Polyarylate, Polyethylene, Polyethylene Terephthalate, Polyethylene Naphthalate, Polyether Sulfide, Polyphenylene Sulfide, Polyphenylene Ether, Polypropylene, Polyvinyl Alcohol , polyamide, polyimide, polyolefin, polyolefin with norcamphene structure, polyvinyl chloride, cellulose-based polymers, or various copolymers of these binary or ternary systems, branch copolymers, blends, etc. These polymer raw materials can be made into alignment objects (stretched films) by stretching or the like.

Examples of liquid crystal polymers include main chain or side chain type polymers in which a conjugative linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. Specific examples of the main-chain type liquid crystal polymer include: for example, nematic alignment polyester-based liquid crystal polymers, discotic polymers or Cholesterol-type polymers, etc. Specific examples of side chain-type liquid crystal polymers include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as the main chain skeleton, and have spacers, mesogens composed of para-substituted cyclic compound units that impart nematic alignment as side chains, etc. Such liquid crystal polymers are, for example, brushed on the surface of a polyimide or polyvinyl alcohol film formed on a glass plate, or on an alignment-treated surface such as silicon oxide deposited obliquely. Above, the liquid crystal polymer solution is expanded and heat-treated.

Retardation film, for example, can be used to compensate for various wavelength plates due to Or for the purpose of coloring or viewing angle due to birefringence of the liquid crystal layer, if there is a phase difference according to the purpose of use, two or more types of phase difference films can be laminated to control the optical characteristics such as phase difference, etc.

The viewing angle compensation film is a film for widening the viewing angle so that the screen can be viewed more clearly even when viewing the screen of a liquid crystal display device from a direction slightly oblique to the screen. The viewing angle compensation film includes, for example, a retardation film, an alignment film of a liquid crystal polymer, or an alignment layer of a liquid crystal polymer supported on a transparent substrate. The usual retardation film is a polymer film with birefringence that is uniaxially stretched in its plane direction. In contrast, the retardation film used as a viewing angle compensation film is used: An axially stretched polymer film with birefringence, or a polymer film with birefringence that is uniaxially stretched in the plane direction and also stretched in the thickness direction to control the refractive index in the thickness direction or oblique alignment Membrane-like biaxially stretched film, etc. The oblique alignment film, for example, includes: a heat-shrinkable film is bonded to a polymer film, and the polymer film is stretched and/or shrunk under the action of the contraction force formed by heating, or a liquid crystal Polymer oblique aligners, etc. The raw material polymer of the phase difference film can be the same as the polymer described in the previous phase difference film, and can be appropriately selected to use: to prevent the coloring of the liquid crystal unit due to the change of the viewing angle caused by the phase difference, etc., Or for the purpose of widening the angle of view for good visibility.

In addition, from the viewpoint of achieving a wide viewing angle with good visibility, the alignment layer of liquid crystal polymer is particularly suitable for the use of an optically different layer composed of a tilted alignment layer of discotic liquid crystal polymer supported by a cellulose triacetate film. View angle compensation film for compatible layer.

[adhesive layer]

In the optical layered body of the present invention, the first adhesive layer and the second adhesive layer are respectively laminated and arranged 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 configured to contain a 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. Adhesives may contain single or multiple resins. It is preferable to use (meth)acrylic resin (A) as the aforementioned resin from the point of view that functionality can be easily imparted to the adhesive by selecting the type of monomer introduced into the resin. The (meth)acrylic resin (A) includes, for example, one mainly composed of a structural unit derived from a (meth)acrylate represented by the following formula (1) (hereinafter also referred to as "monomer (1)"). Polymer. In the present invention, the so-called "polymer mainly composed of structural units derived from monomer (1)" means that it preferably contains The structural unit is 40% by mass or more, preferably 60% by mass or more, such as 80% by mass or more. In this case, it usually contains 100% by mass or less, preferably 90% by mass or less, relative to all structural units constituting the polymer. Structural unit from monomer (1).

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

In one embodiment of the present invention, the (meth)acrylic resin (A), in addition to the structural unit derived from (meth)acrylate (monomer (1)), may further contain other structural units, especially derived from The structural unit of the monomer of the polar functional group is preferably a structural unit derived from a (meth)acrylic compound having a polar functional group. Polar functional groups include carboxyl groups, hydroxyl groups, amino groups, heterocyclic groups represented by epoxy rings, and the like. (Meth)acrylic compounds having polar functional groups, such as (meth)acrylic acid, 2-(dimethylamino)ethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate , and glycidyl acrylate, etc. In addition, the (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 (1). Structural units (monomers) that can be preferably used include those derived from monomers having one olefinic double bond and at least one aromatic ring in the molecule, preferably those derived from (methyl) monomers having an aromatic ring. ) Structural unit of acrylic compounds. In this specification, "(meth)acrylic acid" means either acrylic acid or methacrylic acid, and "(meth)" also has the same meaning when it is referred to as (meth)acrylate or the like.

In the monomer (1), ^R2 is an alkyl group, and more specifically, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, n-octyl acrylate, and dodecyl acrylate can be exemplified Linear alkyl acrylates; branched alkyl acrylates of isobutyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate; methyl methacrylate, ethyl methacrylate, methyl Propyl acrylate, n-butyl methacrylate, n-octyl methacrylate, and linear alkyl methacrylates of lauryl methacrylate; and isobutyl methacrylate, 2-ethyl methacrylate Hexyl methacrylate and branched alkyl methacrylate of isooctyl methacrylate.

Among them, n-butyl acrylate is preferable, and specifically, in all structural units (monomers) constituting the (meth)acrylic resin (A), it is preferable that n-butyl acrylate accounts for 50% by mass or more, and The stipulations regarding the aforementioned monomer (1) are satisfied.

In the monomer (1), R ² is an aralkyl group, and specific examples thereof include benzyl acrylate, benzyl methacrylate, and the like.

These monomers (1) can be used alone or in combination, respectively.

The hydrogen atom of the alkyl or aralkyl group constituting R ² in the aforementioned formula (1) may also be substituted by the group -O-(C ₂ H ₄ O) _n -R ³ .

When the hydrogen atom of the alkyl or aralkyl group constituting R in the aforementioned formula (1) is substituted by the group -O-(C ² H ₄ O) _n -R ³ , n is preferably 0 or ₁ to 4 An integer, preferably 0, 1 or 2. In addition, R ³ is an alkyl or aryl group having 12 or less carbon atoms, and if the alkyl group has 3 or more carbon atoms, it may be straight or branched. List the examples of the aryl group that constitutes ^R3 . In addition to phenyl or naphthyl, there are phenyls, biphenyls (or phenyls) substituted by nuclear alkyls such as tolyls or xylyls, ethylphenyls, etc. phenyl) etc. R ³ is particularly preferably such an aryl group.

R in formula (1) ² is an alkyl group or an aralkyl group and the hydrogen atom of the alkyl group or aralkyl group of R ² is replaced by a group -O-(C ₂ H ₄ O) _n -R ³ (methyl ) acrylate, specifically 2-methoxyethyl acrylate, ethoxymethyl acrylate, 2-phenoxyethyl acrylate, 2-(2-phenoxyethoxy)ethyl acrylate, and Alkoxyalkyl, aryloxyalkyl or aryloxyethoxyalkyl acrylates of 2-(o-phenylphenoxy)ethyl acrylate; 2-methoxyethyl methacrylate, methyl Ethoxymethyl acrylate, 2-phenoxyethyl methacrylate, 2-(2-phenoxyethoxy)ethyl methacrylate, and 2-(o-phenylphenoxy ) alkoxyalkyl esters, aryloxyalkyl esters or aryloxyethoxyalkyl esters of methacrylic acid such as ethyl esters.

The (meth)acrylic resin (A) of the present invention may contain a structural unit derived from a monomer having no polar functional group other than the monomer (1). Monomers other than monomer (1) that do not have polar functional groups include (meth)acrylate monomers, styrene-based monomers, vinyl-based monomers, and A monomer having multiple (meth)acryl groups in the molecule, etc.

Next, the (meth)acrylate monomer having an alicyclic structure in the molecule will be described. The alicyclic structure refers to a cycloparaffin structure with a carbon number of usually 5 or more, preferably about 5 to 7. Specific examples of acrylate monomers having an alicyclic structure are given, including isobornyl acrylate, cyclohexyl acrylate, dicyclopentyl acrylate, cyclododecyl acrylate, methylcyclohexyl acrylate, triacrylic acid Methylcyclohexyl, tertiary butylcyclohexyl acrylate, α-ethoxycyclohexyl acrylate, cyclohexylphenyl acrylate, etc. In addition, specific examples of methacrylate monomers having an alicyclic structure are listed, such as isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentyl methacrylate, cyclododecyl methacrylate Alkyl esters, methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, tertiary butylcyclohexyl methacrylate, cyclohexylphenyl methacrylate, etc.

List examples of styrenic monomers, except styrene In addition, there are methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl Alkylstyrenes of the type styrene, heptylstyrene, and octylstyrene; halogenated styrenes of the type fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; in addition, there are Nitrostyrene, acetylstyrene, methoxystyrene, divinylbenzene, etc.

Examples of vinyl monomers include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate and vinyl laurate; vinyl chloride and vinyl bromide vinylidene halides; vinylidene chlorides; vinylpyridine, vinylpyrrolidone and vinylcarbazole nitrogen-containing aromatic vinyls; butadiene, isoprene and chloroprene Conjugated diene monomers of olefins; in addition, there are acrylonitrile, methacrylonitrile, etc.

Examples of (meth)acrylamide derivatives include N-methylol (meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, N-(3 -Hydroxypropyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, N-(5-hydroxypentyl)(meth)acrylamide, N-( 6-Hydroxyhexyl)(meth)acrylamide, N-(methoxymethyl)acrylamide, N-(ethoxymethyl)(meth)acrylamide, N-(propoxymethyl)( Meth)acrylamide, N-(butoxymethyl)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(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-acrylamide-2-methyl- 1-propanesulfonic acid, etc.

Examples of monomers with multiple (meth)acryl groups in the molecule include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate Alcohol ester, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate Alcohol esters, and tripropylene glycol di(meth)acrylates have two (meth)acrylic acid monomers in the molecule; trimethylolpropane tri(meth)acrylate, etc. have 3 (meth)acryl monomers, etc.

The monomers constituting the (meth)acrylic resin (A) may contain two or more (meth)acrylic esters represented by the above formula (1), and optionally monomers with polar functional groups and/or A monomer other than the monomer (1) that does not have a polar functional group.

The resin contained in the adhesive is based on Gel Permeation Chromatography (GPC: Gel Permeation Chromatography), and the weight average molecular weight Mw in terms of standard polystyrene is not particularly limited, but Mw is preferably in the range of 500,000 to 2 million. Range, Yujia is located in the range of 500,000 to 1.8 million. When the weight average molecular weight in terms of standard polystyrene is 500,000 or more, the adhesiveness under high temperature and high humidity can be improved, and there is a possibility of floating or peeling between the transparent plate or the image display unit and the adhesive layer. The tendency is to decrease, and the reprocessing property also has a tendency to increase. In addition, when the weight average molecular weight is 2 million or less, even if the size of the protective film bonded to the adhesive layer changes, the adhesive layer also changes in accordance with the size change, so the brightness of the peripheral portion of the liquid crystal cell and the center It is preferable because there is no difference in the luminance of the parts, and there is a tendency to suppress white spots or color unevenness. to heavy The molecular weight distribution represented by the ratio Mw/Mn of the number average molecular weight Mw to the number average molecular weight Mn is not particularly limited, and is preferably within a range of about 3 to 15, for example.

The resin contained in the adhesive can be produced by various generally known methods such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization, for example. In the production of the resin, a polymerization initiator can be used in an amount of about 0.001 to 5 parts by mass based on 100 parts by mass of all the monomers used in the production of the resin.

As a polymerization initiator, a thermal polymerization initiator, a photopolymerization initiator, or the like can be used. As a photoinitiator, 4-(2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone etc. are mentioned, for example. Thermal polymerization initiators, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane alkane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxy Valeronitrile), dimethyl-2,2'-azobis(dimethylpropionate), and 2,2'-azobis(2-hydroxymethylpropionitrile) azo compounds; Lauryl peroxide, tertiary butyl hydroperoxide, benzoyl peroxide, tertiary butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di Propyl peroxydicarbonate, tertiary butyl peroxyneodecanoate, tertiary butyl peroxyvalerate, and peroxide (3,5,5-trimethylhexyl) organic peroxides; potassium persulfate, ammonium persulfate, and inorganic peroxides such as hydrogen peroxide. In addition, a redox system initiator in which a peroxide and a reducing agent are used in combination can also be used as a polymerization initiator.

The method for producing the (meth)acrylic resin (A) is preferably a solution polymerization method among the methods shown above. List the solution polymerization Specific examples include mixing desired monomers and organic solvents, adding thermal polymerization initiators under nitrogen atmosphere, and stirring at about 40 to 90°C, preferably about 50 to 80°C for 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 dissolved in an organic solvent. Here, organic solvents such as aromatic hydrocarbons such as toluene or xylene; esters of ethyl acetate or butyl acetate; aliphatic alcohols of propanol or isopropanol; acetone, methylethyl Ketones and methyl isobutyl ketones, etc.

In the present invention, the adhesive constituting the adhesive layer may contain other additives in addition to the above resins. Other additives, such as cross-linking agents, silane compounds, cross-linking catalysts, weather-resistant stabilizers, adhesives (Tackifier), plasticizers, softeners, dyes, pigments, inorganic fillers, organic acids, anti- Static agent, and organic acid metal salt, etc.

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

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

The isocyanate compound is a compound having at least two isocyanate groups (-NCO) in the molecule, for example, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, Hydrogen xylene diisocyanate, diphenylmethane diisocyanate Esters, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, etc. In addition, the adducts obtained by reacting glycerin or trimethylolpropane polyols with these isocyanate compounds, or those obtained by dimerizing and trimerizing isocyanate compounds, can also become adhesives. The cross-linking agent used in the agent. It is also possible to mix and use 2 or more types of isocyanate type compounds.

Epoxy compound is a compound having at least two epoxy groups in the molecule, for example, bisphenol A type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin Diglycidyl ether, glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, N,N-diglycidyl aniline, N,N,N',N '-Tetraglycidyl m-xylylenediamine, etc. You may mix and use 2 or more types of epoxy-type compounds.

Metal chelate compounds, for example, polyvalent compounds that coordinate acetylacetone or ethyl acetylacetate to aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium Compounds made of metals, etc.

Aziridine-based compounds are compounds having at least two 3-membered ring skeletons called ethyleneimines in the molecule, which are composed of 1 nitrogen atom and 2 carbon atoms. Examples include diphenyl Methane-4,4'-bis(1-aziridinecarboxamide), toluene-2,4-bis(1-aziridinecarboxamide), triethylenemelamine, isobutyrylbis-1-(2 -methylaziridine), tri-1-aziridinylphosphine oxide, hexamethylene-1,6-bis(1-aziridinecarboxamide), trimethylolpropane tri-β- Aziridinyl propionate, tetramethylolmethane tris-β-aziridinyl propionate, and the like.

Among these crosslinking agents, it is preferable to use: adducts obtained by reacting isocyanate compounds, especially toluene diisocyanate, with polyols; dimers of toluene diisocyanate, trimers of toluene diisocyanate , the adduct obtained by reacting hexamethylene diisocyanate with polyol; the addition obtained by reacting the dimer of hexamethylene diisocyanate, the trimer of hexamethylene diisocyanate, and the reaction of toluene diisocyanate with polyol adducts obtained by reacting hydrogenated xylene diisocyanate with polyols; isophorone diisocyanate, and/or adducts obtained by reacting isophorone diisocyanate with polyols; these Mixtures of isocyanate compounds, etc.

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

When bonding the optical layered body of the present invention to a transparent plate (for example, a glass plate) via an adhesive, the adhesive of the present invention preferably contains a silane compound from the viewpoint of improving the adhesion with the glass substrate. In particular, it is preferable to contain a silane-based compound in the resin before compounding the crosslinking agent.

Silane compounds, such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxy Silane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxy Silane, 3-Chloropropyltrimethoxysilane, 3-Methacryloxypropyltrimethoxysilane, 3-Mercaptopropyltrimethoxysilane, 3-Glycidoxypropyltrimethoxysilane , 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethyl Silane, 3-glycidoxypropylethoxydimethylsilane, etc. Two or more types of silane compounds can be used.

The silane compound may be in the form of a polysiloxane oligomer. When the polysiloxane oligomer is represented as a (monomer)-(monomer) copolymer, the following are mentioned, for example.

3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, and 3-Mercaptopropyltrimethoxysilane-tetraethoxysilane copolymers containing mercaptopropyl group; mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane Silane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyl-containing copolymers of mercaptomethyltriethoxysilane-tetraethoxysilane copolymer; 3-methacryl Oxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloxypropyltriethoxysilane -Tetramethoxysilane copolymer, 3-methacryloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-methacryloxypropylmethyldimethoxysilane-tetramethoxysilane Silane copolymer, 3-methacryloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer and 3-methacryloxypropylmethyldiethoxysilane-tetraethoxysilane copolymers containing methacryloxypropyl; 3-acryloxypropyltrimethyl Oxysilane-Tetramethoxysilane Copolymer, 3-Acryloxypropyl Trimethoxysilane-Tetraethoxysilane Copolymer 3-acryloxypropyl triethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropyl triethoxysilane-tetraethoxysilane copolymer, 3-acryloxypropyl Methyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloxypropylmethyldiethoxysilane -Tetramethoxysilane copolymer, and 3-acryloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer containing acryloxypropyl copolymer; vinyltrimethoxysilane-tetraethoxysilane Methoxysilane copolymer, vinyl trimethoxysilane-tetraethoxysilane copolymer, vinyl triethoxysilane-tetramethoxysilane copolymer, vinyl triethoxysilane-tetraethoxysilane copolymer, vinyl formazan Dimethoxysilane-tetramethoxysilane copolymer, vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldimethoxysilane copolymer Vinyl-containing copolymers such as diethoxysilane-tetraethoxysilane copolymers; these silane-based compounds are mostly liquid. The content of the silane compound in the adhesive is usually 0.01 to 10 parts by mass, preferably 0.03 to 2 parts by mass, more preferably 0.03 to 1 part by mass, based on 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, as previously explained, in relation to the thickness (T2) of the polarizer, only the total thicknesses T1 and T2 of all the adhesive layers in the optical laminate The ratio (T2/T1) should just be 0.6 or less, and can be appropriately determined independently.

In one embodiment, the optical layered body of the present invention can be It is bonded to the image display unit described later through the first adhesive layer, and bonded 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.

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 suppressing yellowing of the optical layered body. From the viewpoint of thinning the layer, etc., it is preferably 30 μm or less, more preferably 27 μm or less, and more preferably 25 μm or less. In addition, 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 suppressing yellowing of the optical laminate. From the viewpoint of thinning the optical layered body, etc., it is preferably 300 μm or less, more preferably 280 μm or less, and more preferably 250 μm or less. When an adhesive layer (another adhesive layer) other than the first adhesive layer and the second adhesive layer is included in the optical laminate, the other adhesive layer, from the viewpoint of suppressing yellowing of the optical laminate, etc., Preferably they are 3 μm or more, particularly preferably 5 μm or more, and are preferably 30 μm or less, particularly preferably 25 μm or less, from the viewpoint of thinning the optical layered body.

In the optical laminate of the present invention, peelable protective sheets may be respectively attached to the surfaces of the first adhesive layer and the second adhesive layer opposite to the polarizing plate. The protective sheet is a sheet used for the purpose of protecting the exposed surface of the adhesive layer from damage or contamination before laminating the optical laminate with the image display unit or transparent plate. By peeling off the protective sheet, and for example Attach the first adhesive layer to the image display unit, and attach the second adhesive layer The agent layer is bonded to the transparent plate to form the image display device of the present invention. That is, neither the first adhesive layer nor the second adhesive layer is removed and assembled in the display device.

The material constituting the protective sheet is, for example, a thermoplastic resin, for example: polyolefin-based resins such as polyethylene-based resins and polypropylene-based resins; polyethylene terephthalate or polyethylene naphthalate; Polyester resins; polycarbonate resins; (meth)acrylic resins, etc.

The optical laminate of the present invention is used by being bonded between a transparent plate and an image display unit through the above-mentioned adhesive layer. The transparent plate is responsible for suppressing the warpage of the image display unit such as a liquid crystal unit, or protecting the image display unit, for example, it is a light-transmitting (preferably optically transparent) plate-shaped body. Transparent panels, which can be single-layer or multi-layer. Transparent panels, sometimes also called transparent front panels. As an image display unit, a liquid crystal unit (element) or an organic EL unit (element) etc. are mentioned.

The transparent plate is required to exhibit sufficient durability even when it is used outdoors or semi-outdoors because it is arranged on the outermost side of the final product including the optical layered product of the present invention. 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 or tempered glass, especially for flexible displays, are preferably polymer films, among which polycarbonate resin (Young's modulus 2 to 3 GPa), acrylic resin (Young's modulus 2 to 3 GPa), acrylic resin (Young's modulus 3 to 4 GPa), polyimide resin (Young's modulus 3 to 5 GPa), polyether resin (Young's modulus GPa).

The above-mentioned transparent plate may have a color filter in a display Sheet layer or TFT layer, transparent electrode layer of touch panel, or glass or polymer film printed with decorative layer. That is, in one embodiment of the present invention, the transparent plate may have one or more pattern layers 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 thereof include a capacitive method, a surface acoustic wave method, a resistive film method, an electromagnetic induction method, an optical sensing method, and an infrared method. The aforementioned transparent board may have functions of anti-reflection, anti-fouling, electromagnetic wave shielding, near-infrared shielding, color adjustment, or glass scattering prevention. In the transparent plate having these functions, for example, at least one film layer having these functions can be laminated on at least one surface 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 through the above-mentioned adhesive layer, thereby providing an image display device including the optical laminate of the present invention (also referred to as "the present invention"). Invented 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 to improve visibility, the refractive index of the adhesive is preferably close to or the same as that of the transparent plate. The image display device of the present invention can suppress the yellowing of the image display part (display) over time, and exhibit a long-term stable image display function.

The optical laminate and image display device of the present invention, except In addition to being used in portable devices such as TVs, personal computers, mobile phones, and tablet terminals, it has a high inhibitory effect on yellowing in high-temperature environments and can exhibit stable image display performance for a long period of time. It is especially well suited for automotive applications that are prone to exposure to harsher temperature environments. Examples of automotive applications include image display devices such as car navigation devices, speedometers, touch panels for air conditioners, reversing displays, and rear displays.

[Example]

The following series give examples and comparative examples to describe the present invention in more detail.

1. Production of polarizer (1)

A polyvinyl alcohol film with a thickness of 75 μm (average degree of polymerization about 2400, saponification degree of 99.9 mole% or more) is stretched about 5 times in the longitudinal direction by dry stretching, and then immersed in 60 After 1 minute in pure water at °C, it was immersed in an aqueous solution at 28 °C with a weight ratio of iodine/potassium iodide/water of 0.05/5/100 for 60 seconds. Then, it was immersed for 300 seconds in an aqueous solution at 72° C. with a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100. Then, after washing with pure water at 26° C. for 20 seconds, drying treatment was performed at 65° C. for 60 seconds to obtain a polarizer (1) with a thickness of 28 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 is 4.0.

2. Production of polarizer (2)

A polyvinyl alcohol film with a thickness of 60 μm (average degree of polymerization about 2400, saponification degree above 99.9 mole%) is stretched about 5 times in the longitudinal direction by dry stretching, and then immersed in 60 After 1 minute in pure water at °C, it was immersed in an aqueous solution at 28 °C with a weight ratio of iodine/potassium iodide/water of 0.05/5/100 for 60 seconds. Then, it was immersed for 300 seconds in an aqueous solution at 72° C. with a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100. Then, after washing with pure water at 26° C. for 20 seconds, drying treatment was performed at 65° C. for 60 seconds to obtain a polarizer (2) 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 (2) at a wavelength of 700 nm is 4.0.

3. Production of polarizer (3)

Except that the temperature of the pure water during washing was changed to 21° C., the same procedure as in “Preparation of Polarizer (2)” was carried out to obtain a polarizer (3) 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 (3) at a wavelength of 700 nm is 3.3.

4. Production of polarizer (4)

Except that the temperature of the pure water during washing was changed to 34°C, the same procedure as in "Preparation of the Polarizer (2)" was carried out to obtain a Polarizer (4) 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 (4) at a wavelength of 700 nm is 4.7.

5. Preparation of UV (Active Energy Ray) Curing Adhesive

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

‧Alicyclic epoxy resin (a1): 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate: manufactured by Daicel Chemical Industries Co., Ltd. "Celloxide (registered trademark) 2021P"

‧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.

6. Preparation of water-based adhesive

A polyvinyl alcohol aqueous solution was prepared by dissolving 3 parts by mass of carboxy-modified polyvinyl alcohol ["KL-318" manufactured by Kuraray Co., Ltd.] with respect to 100 parts by mass of water. Next, 1.5 parts by mass of water-soluble polyamide polyamine epoxy resin ["Sumirez Resin 650 (30), solid content concentration 30% by weight" manufactured by Tianoka Chemical Industry Co., Ltd.] was added to 100 parts by mass of water in the solution. ] to the aqueous solution and mixed to obtain a water-based adhesive.

[Example 1]

An optical layered body (1) was produced in the following manner.

Using a bar coater, apply the ultraviolet curable adhesive prepared in the above 5. to a 40 μm thick triacetyl cellulose film (TAC: Triacetyl Cellulose) so that the film thickness after curing becomes about 2 μm[ One side of product name "KC4UA" manufactured by Konica Minolta Opto Co., Ltd., moisture permeability 830g/m ² ‧24 hours]. A polarizer (1) was bonded to the coated surface. Then corona discharge treatment was applied to one side of the unstretched norcamphene-based resin with a thickness of 23 μm [trade name "ZEONOR" manufactured by Zeon Japan Co., Ltd., moisture permeability 20 g/m ² ‧ 24 hours], and used A bar coater applied the above-mentioned ultraviolet curable adhesive to the corona discharge-treated surface so that the film thickness after curing was about 2 μm. The polarizer (1) with the above-mentioned cellulose triacetate film bonded on one side was bonded to the coated surface with the polarizer side to prepare a laminate. Using an ultraviolet irradiation device with a conveyor belt ["D Lamp" manufactured by Fusion UV Systems Co., Ltd. was used as the lamp], ultraviolet rays were irradiated from the cellulose triacetate film side of the laminate so that the cumulative light intensity became 250 mJ/ ^cm2 , and the UV curable adhesive hardens.

Then, using a bonding device ["LPA3301" manufactured by Fujipla Co., Ltd.], apply an acrylic adhesive (manufacturing source: Lintec Co., Ltd., model: #7) on the ZEONOR surface side to form a 25 μm-thick an adhesive layer. In addition, an acrylic adhesive (manufacturing source: Lintec Co., Ltd., model: #7) was applied to the TAC surface side using the bonding apparatus described above to form a second adhesive layer with a thickness of 25 μm. Thereby, an optical layered body (1) was obtained.

At this time, the total thickness T1 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) is 50 μm, the thickness T2 of the polarizer is 28 μm, and T2/ T1 is 0.56.

[Example 2]

The polarizer (2) was used instead of the polarizer (1), and the thicknesses of the first adhesive layer and the second adhesive layer were respectively set to 20 μm. Other operations were performed in the same manner as in Example 1 to obtain an optical laminate. body (2). 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 23 μm, and T2/ T1 is 0.58.

[Comparative example 1]

An optical layered body (3) was produced in the following manner.

Apply the above-mentioned water-based adhesive to both sides of the above-mentioned polarizer (1), and use a bonding device ["LPA3301" manufactured by Fujipla Co., Ltd. ], a cellulose triacetate film (TAC) [trade name "KC4UA" manufactured by Konica Minolta Opto Co., Ltd.] with a thickness of 40 μm after being corona-treated on one side was attached to one side of the polarizer (1) As a protective film, a norbornene-based resin [trade name "ZEONOR" manufactured by Zeon Japan Co., Ltd.] with a thickness of 23 μm that was corona-treated on one side and not stretched was bonded to a polarizer (1 ) on the other side. 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 (manufacturing source: Lintec Co., Ltd., model: #7) was applied to the ZEONOR surface using the above laminating device to form a first adhesive layer with a thickness of 25 μm. In addition, an acrylic adhesive (manufacturing source: Lintec Co., Ltd., model: #7) was applied to the TAC surface side using the bonding apparatus described above to form a second adhesive layer with a thickness of 25 μm. Thereby, an optical layered body (3) was obtained.

At this time, the total thickness T1 of all the adhesive layers in the optical laminate (3) (that is, the total thickness of the first adhesive layer and the second adhesive layer) is 50 μm, the thickness T2 of the polarizer is 28 μm, and T2/ T1 is 0.56.

[Comparative example 2]

Except having set the thickness of the 1st adhesive layer and the 2nd adhesive layer to 20 micrometers respectively, it carried out similarly to the comparative example 1, and obtained the optical laminated body (4). At this time, the total thickness 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) T1 is 40 μm, the thickness T2 of the polarizer is 28 μm, T2/ T1 is 0.70.

[Example 3]

Except having used the polarizer (3) instead of the polarizer (2), it carried out similarly to Example 2, and obtained the optical layered body (5). 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 4]

Except having used the polarizer (4) instead of the polarizer (2), it carried out similarly to Example 2, and obtained the optical layered body (6). At this time, the total thickness T1 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) is 40 μm, the thickness T2 of the polarizer is 23 μm, and T2/ T1 is 0.58.

[Reference example 1]

Except not having formed the 2nd adhesive layer, it carried out similarly to the comparative example 2, and obtained the optical laminated body (7). At this time, all of the optical laminates (7) The total thickness T1 of the adhesive layer (that is, the total thickness of the first adhesive layer and the second adhesive layer) is 20 μm, the thickness T2 of the polarizer is 28 μm, and T2/T1 is 1.40.

[Yellowing evaluation (105°C)]

The optical laminates (1) to (6) obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were respectively cut into a size of 30mm×30mm, and each of the first adhesive layer and the second adhesive layer The surface was bonded to an alkali-free glass [trade name "EAGLE XG", manufactured by Corning], and an evaluation sample was prepared. In addition, the optical layered body (7) obtained in Reference Example 1 was cut into a size of 30mm×30mm, and the surface of the first adhesive layer was attached to an alkali-free glass [trade name "EAGLE XG" from Corning Co. System acquisition] to make evaluation samples.

After autoclaving the evaluation sample at a temperature of 50°C and a pressure of 5kg/cm ² (490.3kPa) for 1 hour, it was placed in an environment of a temperature of 23°C and a relative humidity of 55% for 24 hours. Then, a heat test was performed for 100 hours of storage in a heating environment at a temperature of 105° C., and the color change before and after heating was visually confirmed. The one with almost no change is A, the one with a slight color change is B, the one with a color change in about half of the polarizer surface is C, and the one with a large color change is confirmed in almost the entire front of the polarizer. The color changer is D. The obtained results are shown in Table 1. The evaluation sample including the optical laminate (7) produced in Reference Example 1 had no color change because the alkali-free glass was laminated on only one side and no polyene was formed, and the evaluation result was A.

[Evaluation of yellowing (95°C)]

Evaluation samples were prepared using the optical laminates (1) to (7) obtained in Examples 1 to 4, Comparative Examples 1 and 2, and Reference Example 1 in the same manner as above. After autoclaving the evaluation sample at a temperature of 50°C and a pressure of 5kg/cm ² (490.3kPa) for 1 hour, it was placed in an environment of a temperature of 23°C and a relative humidity of 55% for 24 hours. Thereafter, a heat test was performed for 100 hours of storage in a heating environment at a temperature of 95° C., and the color change before and after heating was visually confirmed. The one with almost no change is A, the one with a slight color change is B, the one with a color change in about half of the polarizer surface is C, and the one with a large color change is confirmed in almost the entire front of the polarizer. The color changer is D. The obtained results are shown in Table 1. The evaluation sample including the optical laminate (7) produced in Reference Example 1 had no color change because the alkali-free glass was laminated on only one side and no polyene was formed, and the evaluation result was A.

[Red Variation Evaluation]

The optical laminates (1) to (6) obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were cut to a size of 150mm×100mm, respectively, and each of the first adhesive layer and the second adhesive layer The surface was bonded to an alkali-free glass [trade name "EAGLE XG", manufactured by Corning], and an evaluation sample was prepared. In addition, the optical layered body (7) obtained in Reference Example 1 was cut into a size of 30mm×30mm, and the surface of the first adhesive layer was attached to an alkali-free glass [trade name "EAGLE XG" from Corning Co. System acquisition] to make evaluation samples.

Then, the evaluation sample was subjected to a heating test in which it was stored in a heating environment at a temperature of 105°C for 30 minutes, and the change in the degree of red decolorization in the state of crossed polarized light before and after heating was visually confirmed. Take the one with almost no change and no red change before and after heating as A, and take the one with a little red decolorization after heating as B, take the person who confirmed obvious red decolorization after heating as C, and take the person who confirmed obvious red decolorization during heating as D. The obtained results are shown in Table 1.

In Examples 1 and 2, the ratio 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 polarizer and the protective film are bonded by an active energy ray-curable adhesive layer In the optical layered body, yellowing hardly occurred after exposure to a high-temperature environment. On the other hand, although the thickness of the polarizer and the total thickness of the adhesive layer are the same as in Example 1, the optical laminate of Comparative Example 1, in which the polarizer and the protective film are bonded via the water-based adhesive layer, is exposed to Yellowing occurs in a high-temperature environment, and especially in the evaluation at 105°C, a larger color change occurs than in the evaluation at 95°C. Furthermore, the ratio of the thickness T2 of the polarizer to the total thickness T1 of the first and second adhesive layers exceeds 0.6, and the polarizer and the protective film are bonded by an aqueous adhesive layer to the optical laminate of Comparative Example 2, Significant yellowing occurs due to exposure to high temperatures of 105°C. this In addition, the optical layered body of Reference Example 1, which does not have the second adhesive layer and only one surface of the optical layered body is covered by a glass plate, hardly yellows after being 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

10‧‧‧polarizer

Claims (6)

An optical laminate comprising a first adhesive layer, a polarizing plate, and a second adhesive layer in sequence, wherein the polarizing plate includes: a polarizing plate, and an active energy ray-curable adhesive layer laminated on the polarizing plate. A protective film on at least one surface of the sheet, the polarizer is a polyvinyl alcohol-based resin film containing a dichroic pigment, the thickness of the polarizer is 30 μm or less, and the absorbance A ₇₀₀ at a wavelength of 700 nm is 3.7 to 4.5; and Assuming that the total thickness of all the adhesive layers included in the optical laminate is T1 and the thickness of the polarizer is T2, T2/T1 is 0.001 to 0.6, and the active energy ray-curable adhesive layer is A layer composed of hardened cationic polymer adhesives containing cationic polymerizable compounds. The optical laminated body described in claim 1 of the patent application is used by bonding between the transparent plate and the image display unit through the aforementioned adhesive layer. The optical laminate according to claim 1 or 2, wherein the polarizer has a thickness of 3 μm or more. The optical laminate as described in claim 1 or 2, wherein the polarizing plate includes a protective film laminated on both sides of the polarizing plate with an active energy ray-curable adhesive, and one of the protective films is Made of cellulose-based polymers. The optical laminate according to claim 1 or 2, wherein the protective film laminated on at least one of the polarizers has a moisture permeability of 200 g/m ² ‧24 hours or more and 2000 g/m ² ‧24 hours or less. An image display device comprising the optical laminate described in any one of items 1 to 5 of the scope of the patent application.

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