WO2015140900A1

WO2015140900A1 - Adhesive sheet for image display device, method for manufacturing image display device using same, and image display device

Info

Publication number: WO2015140900A1
Application number: PCT/JP2014/057130
Authority: WO
Inventors: 豪鈴木; 山崎　浩二; 陽介星; 要一郎満生; 中村　智之; 泉樹佐藤
Original assignee: 日立化成株式会社
Priority date: 2014-03-17
Filing date: 2014-03-17
Publication date: 2015-09-24
Also published as: JPWO2015140900A1

Abstract

An adhesive sheet for an image display device comprises (A) a structural unit that derives from an alkyl (meth)acrylate with an alkyl group having 4 to 18 carbon atoms, (B) a structural unit that derives from a butane (butadiene) polymer, and (C) a photoinitiator. The component (A) preferably includes (A1) a (meth)acrylic acid derivative polymer and (A2) a (meth)acrylic acid derivative monomer having one (meth)acryloyl group in the molecule. The component (B) preferably includes a compound having a bifunctional (meth)acryloyl group.

Description

Adhesive sheet for image display device, method for manufacturing image display device using the same, and image display device

The present invention relates to an adhesive sheet for an image display device, an image display device manufacturing method using the same, and an image display device.

In recent years, a gap between a transparent protective plate or an information input device (such as a touch panel) in an image display device and a display surface of an image display unit or a gap between a transparent protective plate and an information input device is compared with air. A method has been proposed in which the refractive index is replaced with a transparent material close to the display surface of the transparent protective plate, the information input device, and the image display unit, thereby improving the transparency and suppressing the decrease in luminance and contrast of the image display device. (For example, Patent Document 1). A schematic example of a liquid crystal display device is shown in FIGS. 1 and 2 as an example of an image display device. The liquid crystal display device with a built-in touch sensor includes a transparent protective plate (glass or plastic substrate) D1, a touch sensor D2, a polarizing plate D3, and a liquid crystal display cell D4. In order to relax and improve visibility, an adhesive layer D5 is provided between the transparent protective plate and the touch panel (touch sensor), and an adhesive layer D6 is provided between the touch sensor D2 and the polarizing plate D3. In some cases. Moreover, as shown in FIG. 2, the adhesion layer D8 may be provided between D7 in which the touch panel is built in the transparent protective plate and the polarizing plate D3.

Among the layer configurations of the image display device described above, there are an adhesive layer D6 provided between the touch sensor and the polarizing plate, and an adhesive layer D8 provided between the polarizing plate and D7 in which the touch sensor is incorporated in the transparent protective plate. The pressure-sensitive adhesive sheet is required to have a low dielectric constant from the viewpoint of removing noise generated from the liquid crystal display device and increasing the sensitivity of the touch panel.

Further, as the use of the above image display device in the global market expands, the visibility of the above image display device does not whiten even under high temperature humidification conditions such as use in high temperature and high humidity areas. It is demanded not to lower

JP 2008-83491 A JP 2010-163591 A

However, the adhesive material on the film described in Patent Document 2 is mainly composed of 2-ethylhexyl acrylate, and has a dielectric constant of 4.3 or more at 23 ° C. and 100 kHz. The shaped adhesive material may reduce the sensitivity of the image display device. Also, in order to lower the dielectric constant, a method of lowering the polarity of the adhesive resin composition is taken, but haze increases when an adhesive sheet using an adhesive resin composition with low polarity under high temperature and high humidity conditions is left unattended. Therefore, there is a concern that the visibility of the image display device using the pressure-sensitive adhesive sheet is lowered.
The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive sheet for image display having a low dielectric constant and low haze even in a high-temperature and high-humidity environment. Moreover, an object of this invention is to provide the manufacturing method of an image display apparatus using the adhesive sheet for image display apparatuses, and an image display apparatus.

As a result of intensive studies to solve the above problems, the present inventors have found that a butane (butadiene) having a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms and a (meth) acryloyl group It has been found that the above-mentioned problems can be solved if the pressure-sensitive adhesive sheet is formed from a pressure-sensitive resin composition containing a structural unit derived from a polymer and has a pressure-sensitive adhesive layer having specific physical properties.
The present invention has been completed based on such findings.

That is, the present invention relates to (A) a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms, (B) a structural unit derived from a butane (butadiene) polymer, and (C) An adhesive sheet for an image display device having an adhesive layer containing a photopolymerization initiator is provided.

The structural unit derived from an alkyl (meth) acrylate having 4 to 18 carbon atoms in the (A) alkyl group of the present invention comprises (A1) (meth) acrylic acid derivative polymer and (A2) (meth) acryloyl group. It is preferably derived from a (meth) acrylic acid derivative monomer having one in the molecule.
Furthermore, the structural unit derived from the (B) butane (butadiene) polymer is preferably derived from a compound having a bifunctional (meth) acryloyl group.

In the present invention, the adhesive layer preferably has a thickness of 50 to 5.0 × 10 ² μm.
In the present invention, the adhesive layer preferably has a dielectric constant of 23 ° C. of 3.0 or less at a measurement frequency of 100 kHz.
Further, in the present invention, the haze after being allowed to stand for 96 hours in an environment of 60 ° C. and 95% RH is preferably 1.0% or less.

In the pressure-sensitive adhesive sheet for an image display device according to the present invention, the pressure-sensitive adhesive layer in these pressure-sensitive adhesive sheets has (A) a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms (A1) ( A structural unit derived from a (B) butane (butadiene) polymer, including a (meth) acrylic acid derivative polymer and (A2) a (meth) acrylic acid derivative monomer having one (meth) acryloyl group in the molecule. By being comprised from the adhesive resin composition containing, it becomes possible for the dielectric constant in 23 degreeC and the measurement frequency of 100 kHz to be 3.0 or less, and can ensure the responsiveness of an image display apparatus. Further, the haze of the pressure-sensitive adhesive layer in these pressure-sensitive adhesive sheets after being left in an environment of 60 ° C. and 95% RH for 96 hours or more can be 1.0% or less, and the image display device having the pressure-sensitive adhesive sheet Can be prevented from lowering the visibility.
That is, the present invention can provide an adhesive sheet for image display having a low dielectric constant and a low haze even in a high temperature and high humidity environment by using the above adhesive resin composition.

The present invention further provides an adhesive sheet for an image display device, further comprising first and second base material layers laminated so as to sandwich the adhesive layer.
According to such an adhesive sheet for an image display device (hereinafter, sometimes simply referred to as “adhesive sheet”), the adhesive sheet can be easily stored and transported without damaging the adhesive layer, and has excellent handling properties. can do.

In addition, the present invention includes a carrier layer further laminated on the second base material layer, and outer edges of the first base material layer and the carrier layer project outward from an outer edge of the adhesive layer. An adhesive sheet for an image display device is provided.

According to such an adhesive sheet, the outer edges of the first base material layer and the carrier layer forming the outer layer may protrude outward from the outer edge of the adhesive layer forming the inner layer. This ensures that the outer edge of the adhesive layer is protected during storage and transportation of the adhesive sheet. Moreover, when sticking an adhesion layer to a to-be-adhered body, a carrier layer can be easily peeled from a 2nd base material layer by pinching the outer edge part of the carrier layer protruding outside. Next, the first base material layer can be easily peeled by pinching the outer edge portion of the first base material layer. At this time, since the second base material layer remains on one side of the adhesive layer, the protection of the adhesive layer by the second base material layer is maintained when one surface of the adhesive layer is attached to the adherend. The Thereafter, the adhesive layer can be disposed between the pair of adherends by peeling off the second base material layer and attaching the other surface of the adhesive layer to another adherend.

The present invention further includes a step of bonding the adherends to each other via an adhesive layer provided in the above-mentioned adhesive sheet for an image display device to obtain a laminate, and the laminate is obtained at 20 ° C. to 80 ° C. and 0.2 MPa to Provided is a method for manufacturing an image display device, comprising: a step of performing heat and pressure treatment under a condition of 0.8 MPa; and a step of irradiating the adhesive layer with ultraviolet rays.

The adherend is preferably at least two selected from a transparent protective plate, a touch panel, or an image display unit.
The production method according to the present invention is particularly useful when the adherend is a transparent protective plate, a touch panel, or an image display unit. Similarly, by using the pressure-sensitive adhesive sheet of the present invention, it is possible to bond members on the viewing side from the image display unit of the image display device. In that case, for example, even if the member on the viewing side has a stepped portion, the adhesive layer can surely embed the stepped portion, and the surface flatness in the vicinity of the stepped portion is excellent, so the visibility can be lowered. Absent.
By using the pressure-sensitive adhesive sheet of the present invention, it is necessary for an image display unit and an image display device, such as an image display unit such as a liquid crystal display unit and a touch panel, the image display unit and a transparent protective plate, and a touch panel and a transparent protective plate. It is possible to bond the members (adherents) to be bonded together.

The present invention comprises an image display unit and a transparent protective plate, and is a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for an image display device or a cured product thereof, which exists between the image display unit and the transparent protective plate. An image display device is provided.
Moreover, this invention is an adhesive layer of the said adhesive sheet for image display apparatuses, or its hardened | cured material which is provided with an image display unit, a touch panel, and a transparent protective board, and is interposed between the said touch panel and the said transparent protective board. An image display device comprising a transparent resin layer is provided.

Further, the present invention provides the image having a step portion between an adherend selected from an image display unit, a touch panel or a transparent protective plate, and the transparent resin layer which is the adhesive sheet for an image display device or a cured product thereof. A display device is provided.
When the pressure-sensitive adhesive layer is excellent in embedding in a step and surface flatness, a step portion is provided between the image display unit, the touch panel or the transparent protective plate and the pressure-sensitive adhesive sheet for image display device or a cured product thereof. Even so, an image display device having both excellent impact resistance and visibility can be obtained.

Since the adhesive sheet for an image display device of the present invention has a low dielectric constant, it is suitable for ensuring the responsiveness of the image display device, and can suppress an increase in haze when left under high temperature and high humidity conditions. It is suitable for preventing a decrease in the visibility of the image display device.

According to the present invention, since the dielectric constant is low, it is suitable for ensuring the responsiveness of the image display device, and the haze increase can be suppressed even when left in a high-temperature and high-humidity environment. A pressure-sensitive adhesive sheet for a display device can be provided. Moreover, this invention can provide the manufacturing method and image display apparatus of an image display apparatus using such an adhesive sheet.

It is sectional drawing which shows one Embodiment of an image display apparatus. It is sectional drawing which shows one Embodiment of an image display apparatus. It is a perspective view which shows one Embodiment of the adhesive sheet (3 layer goods) which concerns on this invention. It is sectional drawing which shows one Embodiment of the adhesive sheet (3 layer goods) which concerns on this invention. It is sectional drawing of a base material film (3 layer goods). It is sectional drawing which shows the cutting process of a base material film (3 layer goods). It is sectional drawing which shows the removal process of the unnecessary part of a base material film (3 layer goods). It is sectional drawing which shows the removal process of a temporary separator. It is sectional drawing which shows the sticking process of a light peeling separator. It is sectional drawing which shows one Embodiment of an image display apparatus. It is sectional drawing which shows one Embodiment of an image display apparatus. It is sectional drawing which shows the peeling process of a light peeling separator. It is sectional drawing which shows the sticking process of the adhesion surface to a to-be-adhered body. It is sectional drawing which shows the peeling process of a heavy peeling separator. It is sectional drawing which shows the sticking process of the adhesion surface to a to-be-adhered body. It is a perspective view which shows one Embodiment of the adhesive sheet (4 layer goods) which concerns on this invention. It is a side view which shows one Embodiment of the adhesive sheet (4 layer goods) which concerns on this invention. It is sectional drawing of a base material film (4 layer goods). It is sectional drawing which shows the cutting process of a base material film (4 layer goods). It is sectional drawing which shows the removal process of the unnecessary part of a base material film (4 layer goods). It is sectional drawing which shows the removal process of the unnecessary part of a heavy peeling separator. It is sectional drawing which shows the removal process of a temporary separator. It is sectional drawing which shows the sticking process of a light peeling separator. It is sectional drawing which shows the peeling process of a carrier film.

Hereinafter, preferred embodiments (first embodiment and second embodiment) of the present invention will be described, but the present invention is not limited to these embodiments. In addition, the description which overlaps with both embodiment shall be demonstrated only in 1st embodiment, and description is abbreviate | omitted suitably in description of 2nd embodiment.
In this specification, “(meth) acrylate” means “acrylate” or “methacrylate” corresponding thereto. Similarly, “(meth) acryl” means “acryl” or “methacryl” corresponding thereto. The “butane (butadiene) polymer” means “butane polymer” or “butadiene polymer”.

[First embodiment]
<Adhesive sheet I for image display device (3-layer product)>
The pressure-sensitive adhesive sheet for an image display device according to this embodiment includes a pressure-sensitive adhesive layer and a pair of base material layers (first and second base material layers) laminated so as to sandwich the pressure-sensitive adhesive layer. It is preferable that the outer edge of the base material layer projects outward from the outer edge of the adhesive layer.

That is, as shown in FIG. 3 and FIG. 4, the pressure-sensitive adhesive sheet 1 A according to this embodiment includes a transparent film-like pressure-sensitive adhesive layer 2 and a heavy release separator 3 (one substrate, second film) sandwiching the pressure-sensitive adhesive layer 2. And a light release separator 4 (the other substrate, the first substrate layer). This adhesive layer 2 is a transparent film disposed between a transparent protective plate and a touch panel or between a touch panel and a liquid crystal display unit in an image display device such as a touch panel display for a portable terminal.

The adhesive layer 2 has an acrylic acid derivative polymer as the component (A1) as a structural unit derived from an alkyl (meth) acrylate having 4 to 18 carbon atoms in the alkyl group as the component (A), A butane having a (meth) acryloyl group as a crosslinking agent containing a (meth) acrylic acid derivative monomer having one (meth) acryloyl group in the molecule and further having a bifunctional (meth) acryloyl group as the component (B) Including a structural unit derived from a polymer or a structural unit derived from a butadiene polymer having a (meth) acryloyl group, the dielectric constant at 23 ° C. and 100 kHz is 3.0 or less. In addition, since the adhesive layer 2 is used in an image display device, the haze value is preferably 0.1% to 1.5%. From a practical viewpoint, it may be 0.1% or more. From the viewpoint of visibility, the haze value is preferably 1.0% or less, more preferably 0.8% or less. Preferably, it is 0.5% or less.
The haze value (haze) is a value representing turbidity. From the total transmittance T of light irradiated through a lamp and transmitted through a sample and the transmittance D of light diffused and scattered in the sample, haze (haze) %) Is determined as (D / T) × 100. These are defined by JIS K 7361 and can be easily measured with a commercially available turbidimeter such as NHD-2000 manufactured by Nippon Denshoku Industries Co., Ltd.

The thickness (film thickness) of the pressure-sensitive adhesive layer 2 is not particularly limited because it is appropriately adjusted depending on the intended use and method, but is preferably 50 μm or more, more preferably 1.2 × 10 ² μm or more, More preferably, it is 1.3 × 10 ² μm or more. Further, it is preferably 5.0 × 10 ² μm or less, more preferably 3.5 × 10 ² μm or less, and even more preferably 3.0 × 10 ² μm or less. When used in the range of this film thickness, from the viewpoints of impact resistance and visibility, a particularly excellent effect is exhibited as a transparent adhesive sheet for laminating an optical member on a display.
Moreover, when using the adhesion layer 2 between a touch panel and a transparent protective board, it is preferable that the dielectric constant in 23 degreeC and 100 kHz of the adhesion layer 2 is 5 or less from a viewpoint of ensuring the responsiveness of a touch panel, and is 4 or less. More preferably, it is more preferably 3 or less. The lower limit of the dielectric constant is preferably 2 or more from the viewpoint of preventing the touch panel sensitivity from decreasing.

Moreover, the adhesion layer 2 applied the adhesive resin composition by arbitrary thickness on the heavy peeling separator 3 (2nd base material layer), for example, and it hardened | cured by irradiating an active energy ray to this. It can also be formed by cutting into a desired size later. Moreover, after adhering adherends together via the adhesion layer 2 and obtaining a laminated body, it can also be hardened by irradiating this with an active energy ray. In the case of a pressure-sensitive adhesive sheet that has been cured by irradiating active energy rays in advance, it is not necessary to bond the adherends together to produce a laminate and then irradiate and cure by activating active energy rays, thus simplifying the work process. . On the other hand, when the laminate is obtained and then cured by irradiating it with active energy rays, the vicinity of the step can be embedded without any gap when the adherend has a step due to the high fluidity of the adhesive layer 2. In addition, since it is crosslinked in a laminated state, it has excellent shape retention.
An adhesive sheet obtained by irradiating an adhesive layer with an active energy ray and cured, and further using this to adhere the adherends together to obtain a laminate, can be further cured by irradiating an active energy ray.

As the light source of the active energy ray, a light source having a light emission distribution at a wavelength of 400 nm or less is preferable. Can be used. The irradiation energy is not particularly limited, but is preferably 8.0 × 10 ² mJ / cm ² or more, more preferably 1.0 × 10 ³ mJ / cm ² or more, and 1.5 × 10 ^3. More preferably, it is mJ / cm ² or more. Further, it is preferably 5.0 × 10 ³ mJ / cm ² or less, more preferably 3.5 × 10 ³ mJ / cm ² or less, and 2.5 × 10 ³ mJ / cm ² or less. More preferably.

The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive sheet of the present invention comprises (A) a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms, and (B) a butane (butadiene) polymer. The derived structural unit and (C) a photopolymerization initiator are contained.
Hereinafter, the adhesive resin composition will be described.

[Component (A): Structural unit derived from alkyl (meth) acrylate having an alkyl group with 4 to 18 carbon atoms]
Component (A): A structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms (hereinafter also referred to as “component (A)”) is (A1) (meth) acrylic. An acid derivative polymer and (A2) a (meth) acrylic acid derivative monomer having one (meth) acryloyl group in the molecule.

[(A1) component: (A) (meth) acrylic acid derivative polymer]
(A1) The (meth) acrylic acid derivative polymer refers to a polymer obtained by polymerizing one kind of monomer having one (meth) acryloyl group in the molecule or copolymerizing two or more kinds. In addition, as long as the effect of this embodiment is not impaired, the component (A1) is a compound having two or more (meth) acryloyl groups in the molecule, or a polymerizable compound having no (meth) acryloyl group. (A compound having one polymerizable unsaturated bond in the molecule such as acrylonitrile, styrene, vinyl acetate, ethylene, propylene, a compound having two or more polymerizable unsaturated bonds in the molecule such as divinylbenzene) ) Copolymerized with an acrylic acid derivative polymer.

(A1) Monomers having one (meth) acryloyl group in the molecule forming the component include, for example, (meth) acrylic acid; (meth) acrylic acid amide; (meth) acryloylmorpholine; methyl (meth) acrylate , Ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) ) Acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate, n-lauryl (meth) acrylate, stearyl (meth) acrylate, etc. ~ 18 a Kill (meth) acrylate; (meth) acrylate having an aromatic ring such as benzyl (meth) acrylate, phenoxyethyl (meth) acrylate; cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, etc. (Meth) acrylates having the following alicyclic groups; tetrahydrofurfuryl (meth) acrylate; N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, N, N-dimethyl ( (Meth) acrylamide derivatives such as (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide; 2- (2-methacryloyloxyethylo ) Ethyl isocyanate, 2- (meth) acrylate having an isocyanate group of acryloyloxyethyl isocyanate (meth) acrylates, and alkylene glycol chain-containing (meth) acrylate.

The (A2) component (meth) acrylic acid derivative monomer having one (meth) acryloyl group in the molecule has a structural unit derived from an alkyl (meth) acrylate having an alkyl group with 4 to 18 carbon atoms. When a compound is used, but an alkyl (meth) acrylate having an alkyl group with 4 to 18 carbon atoms is copolymerized with the (meth) acrylic acid derivative polymer of the component (A1), the component (A1) and the component (A2) Since the compatibility of the components is high, the transparency of the adhesive layer is improved. Furthermore, it is preferable because the dielectric constant decreases.

From the above viewpoint, the component (A2) is preferably an alkyl (meth) acrylate having 1 to 18 carbon atoms in the alkyl group, and more preferably an alkyl (meth) acrylate having 4 to 18 carbon atoms in the alkyl group. ) Acrylates are more preferred, alkyl (meth) acrylates having 10 to 18 carbon atoms in the alkyl group are more preferred, and stearyl (meth) acrylate is particularly preferred.
The content ratio of the alkyl group having 1 to 18 carbon atoms (meth) acrylate in the alkyl group is preferably 50% by mass or more, more preferably 60% by mass or more, based on the total mass of the copolymerized polymer. Preferably, it is 70 mass% or more. Moreover, it is preferable that it is 95 mass% or less, and it is more preferable that it is 90 mass% or less. When the content of alkyl (meth) acrylate having 1 to 18 carbon atoms in the alkyl group is in such a range, the adhesion between the adhesive layer and the transparent protective plate (glass substrate, plastic substrate, etc.) is further improved, and adhesion is achieved. Peeling between the layer and the adherend can be prevented. In general, a polymer having such a copolymerization ratio can be obtained by blending each monomer in the same ratio as that of the copolymer and copolymerizing the monomers. The polymerization rate is more preferably substantially close to 100% by mass.

In the above alkyl group having 1 to 18 carbon atoms (meth) acrylate, stearyl (meth) acrylate is preferably contained. Examples of stearyl (meth) acrylate include n-stearyl (meth) acrylate (also referred to as octadecyl (meth) acrylate), isostearyl (meth) acrylate (also referred to as 16-methylheptadecyl (meth) acrylate), and the like. Among these, isostearyl (meth) acrylate is more preferable. These stearyl (meth) acrylates may be used in combination of two or more.

Other monomers copolymerized with alkyl (meth) acrylates having 1 to 18 carbon atoms in the alkyl group, particularly stearyl (meth) acrylate, are not limited to those described above, but include hydroxyl groups, morpholino groups, amino groups, carboxyls. A monomer having a polar group such as a group, a cyano group, a carbonyl group, a nitro group or a group derived from alkylene glycol is preferred. The (meth) acrylate having these polar groups improves the adhesiveness between the adhesive layer and the transparent protective plate.

In particular, it is preferable to use stearyl (meth) acrylate in combination with an alkylene glycol chain-containing (meth) acrylate represented by the following general formula (b).
_{_{_{_{CH 2 = CR 2 COO (C}}}} p H 2p O) q R 3 ··· (b)
In the general formula (b), R ₂ represents a hydrogen atom or a methyl group, R ₃ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, p represents an integer of 2 to 4, and q represents 1 to 10 Indicates an integer.

Examples of the (meth) acrylate having an alkylene glycol chain represented by the general formula (b) include 2-hydroxyethyl (meth) acrylate, 1-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3- Hydroxypropyl (meth) acrylate, 1-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 1-hydroxybutyl (meth) (Meth) acrylate having hydroxyl group such as acrylate; diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, hexaethylene glycol Polyethylene glycol mono (meth) acrylates such as polyol mono (meth) acrylate; polypropylene glycol mono (meth) acrylates such as dipropylene glycol mono (meth) acrylate, tripropylene glycol mono (meth) acrylate and octapropylene glycol mono (meth) acrylate Polybutylene glycol mono (meth) acrylates such as dibutylene glycol mono (meth) acrylate and butylene glycol mono (meth) acrylate; methoxytriethylene glycol (meth) acrylate, methoxytetraethylene glycol (meth) acrylate, methoxyhexaethylene Glycol (meth) acrylate, methoxyoctaethylene glycol (meth) acrylate, methoxynonaethylene glycol Alkoxy (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxyheptapropylene glycol (meth) acrylate, ethoxytetraethylene glycol (meth) acrylate, butoxyethylene glycol (meth) acrylate, butoxydiethylene glycol (meth) acrylate, etc. Examples include polyalkylene glycol (meth) acrylate.
Of these, 2-hydroxyethyl (meth) acrylate, 1-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 1-hydroxypropyl from the viewpoint of adhesiveness (Meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 1-hydroxybutyl (meth) acrylate are preferred, and 2-hydroxyethyl (meth) An acrylate and 4-hydroxybutyl (meth) acrylate are more preferable, and 2-hydroxyethyl (meth) acrylate is still more preferable. Further, these (meth) acrylates having an alkylene glycol chain may be used in combination of two or more.

The weight average molecular weight of the component (A1) is preferably 1.5 × 10 ⁴ or more, converted to 2.0 × 10 ⁴ or more using a standard polystyrene calibration curve by gel permeation chromatography (GPC). more preferably ⁴ or more, further preferably 2.5 × 10 ⁴ or more. When the weight average molecular weight is 1.5 × 10 ⁴ or more, an adhesive layer having an adhesive force that is less likely to be peeled off from the transparent protective plate or the like can be obtained. On the other hand, the weight average molecular weight is preferably 3.0 × 10 ⁵ or less, more preferably 2.0 × 10 ⁵ or less, and further preferably 1.0 × 10 ⁵ or less. When the weight average molecular weight is 3.0 × 10 ⁵ or less, the viscosity of the adhesive resin composition does not become too high, and the processability when forming a sheet-like adhesive layer becomes better.

As the polymerization method for the component (A1), known polymerization methods such as solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization can be used.

As the polymerization initiator for polymerizing the component (A1), a compound that generates a radical by heat can be used. Specifically, organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butylperoxy-2-ethylhexanoate; 2,2′-azobisisobutyronitrile, 2,2′-azobis And azo compounds such as (2-methylbutyronitrile).

The content of the component (A1) is preferably 30% by mass or more, more preferably 40% by mass or more, and more preferably 50% by mass or more with respect to the total mass of the adhesive resin composition. Further preferred. In addition, the content of the same component is preferably 90% by mass or less, more preferably 80% by mass or less, and 70% by mass or less with respect to the total mass of the adhesive resin composition. Further preferred. When the content of the component (A) is in such a range, the viscosity of the adhesive resin composition falls within an appropriate viscosity range for producing the adhesive layer, and the workability becomes better. Further, the obtained adhesive layer has better adhesion to a transparent protective plate such as a glass substrate or a plastic substrate, and surface flatness.

[(A2) component: (A2) (meth) acrylic acid derivative monomer having one (meth) acryloyl group in the molecule]
The (A) component (meth) acrylic acid derivative monomer having one (meth) acryloyl group in the molecule is a structural unit derived from an alkyl (meth) acrylate having an alkyl group with 4 to 18 carbon atoms. Including at least. These include the same compounds as those exemplified as the monomer having one (meth) acryloyl group in the molecule that forms the component (A1).

In addition, in this embodiment, it is preferable that (A2) component contains a stearyl (meth) acrylate from a viewpoint of adhesiveness, transparency, and a dielectric constant. Moreover, it is preferable that (A2) component contains a hydroxyl-containing (meth) acrylate from a viewpoint of adhesiveness, transparency, and handleability.

In the adhesive layer 2, the structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms is a (meth) acrylic acid derivative polymer component of the component (A1) constituting the adhesive resin composition Further, it may be attributed to the monomer component (A2). That is, by adding a structural unit derived from an alkyl (meth) acrylate having an alkyl group with 4 to 18 carbon atoms in the polymer component, the structural unit is added to the adhesive resin composition, The structural unit may be imparted by including an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms in the component. However, the structural unit is preferably derived from both the polymer component (A) and the monomer component (A2) from the viewpoint of improving the transparency of the pressure-sensitive adhesive layer 2.

A structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 to 18 carbon atoms is a main component of the adhesive layer 2. In the present invention, the main component means the largest component among the components constituting the adhesive layer 2.
The content of the structural unit derived from the alkyl (meth) acrylate having 4 to 18 carbon atoms in the alkyl group is such that the content of the polymer and the monomer is the total mass from the viewpoint of improving the adhesiveness, transparency and handleability. On the other hand, it is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably 50% by mass or more. From the same viewpoint, the same content is preferably 90% by mass or less, more preferably 85% by mass or less, and further preferably 80% by mass or less.
The structural unit derived from an alkyl (meth) acrylate having an alkyl group of 4 to 18 carbon atoms in the component (A2) is preferably stearyl (meth) acrylate. Examples of stearyl (meth) acrylate include n-stearyl (meth) acrylate (also referred to as octadecyl (meth) acrylate), isostearyl (meth) acrylate (also referred to as 16-methylheptadecyl (meth) acrylate), and the like. Among these, isostearyl (meth) acrylate is more preferable. These stearyl (meth) acrylates may be used in combination of two or more.

The content of the component (A2) is preferably 5% by mass or more, more preferably 15% by mass or more, and further preferably 25% by mass or more with respect to the total mass of the adhesive resin composition. preferable. Moreover, it is preferable that it is 65 mass% or less, It is more preferable that it is 55 mass% or less, It is still more preferable that it is 45 mass% or less. When the content of the component (A2) is in such a range, the viscosity of the pressure-sensitive adhesive resin composition falls within an appropriate viscosity range for producing the pressure-sensitive adhesive layer, and the workability becomes better. Moreover, it will become more excellent also in the adhesiveness and transparency of the obtained adhesive sheet. And the peel strength to the glass in the high temperature between the obtained adhesion layer and a to-be-adhered body becomes a higher thing.

[(B) Component: (B) Structural Unit Derived from Butane (Butadiene) Polymer]
As the structural unit derived from the butane (butadiene) polymer as the component (B), a compound having a bifunctional (meth) acryloyl group is included. Other specific examples of the component (B) include urethane di (meth) acrylate having a urethane bond, side chain (meth) acryl-modified (meth) acrylate polymer, polypropylene glycol di (meth) acrylate, polyurethane propylene glycol mono (meth) Examples include acrylates, polyethylene glycol (meth) acrylates, polyethylene glycol mono (meth) acrylates, polyester polymers having (meth) acryloyl groups, and isoprene polymers having (meth) acryloyl groups. Among these, a butane (butadiene) polymer having a (meth) acryloyl group is preferable from the viewpoint of reducing the dielectric constant and preventing whitening that prevents an increase in haze in a high temperature and high humidity environment.

Examples of the butane (butadiene) polymer having a (meth) acryloyl group include compounds represented by the following general formulas (c) and (d).

In the general formulas (c) and (d), m represents a number of 50 to 1000, n represents a number of 1 to 5, and R ₄ represents a hydrogen atom or a methyl group. m is preferably from 100 to 800, more preferably from 150 to 700, and even more preferably from 200 to 600. n is preferably 1.5 to 4, more preferably 2 to 3.5, and still more preferably 2 to 3.
The component (B) preferably has a weight average molecular weight of 3.0 × 10 ² or more, more preferably 5.0 × 10 ² or more, from the viewpoint of further suppressing generation of bubbles and peeling at high temperature or high temperature and high humidity. More preferably. From the same viewpoint, it is preferably 1.0 × 10 ⁵ or less, and more preferably 7.0 × 10 ⁴ or less.

The content of the component (B) varies depending on the modification rate of the side chain. However, if the content is too large, the adhesive strength is reduced, and problems such as peeling and bubbles are likely to occur. The holding force tends to be low and the reliability tends to decrease.
(B) It is preferable that content of a component is 15 mass% or less with respect to the total mass of an adhesive resin composition. When the content is 15% by mass or less, since the crosslinking density does not become too high, an adhesive layer having more sufficient adhesiveness, high elasticity, and no brittleness can be obtained. Furthermore, the content of the component (B) is more preferably 10% by mass or less, and still more preferably 7% by mass or less, from the viewpoint of further improving the step embedding property.

(B) Although there is no restriction | limiting in particular about the minimum of content of a component, it should be 0.1 mass% or more with respect to the total mass of an adhesive resin composition from a viewpoint which makes film-forming property more favorable. It is preferably 2% by mass or more, more preferably 3% by mass or more.

[(C) component: (C) photopolymerization initiator]
(C) component accelerates | stimulates hardening reaction by irradiation of an active energy ray. Here, active energy rays refer to ultraviolet rays, electron beams, α rays, β rays, γ rays and the like.

The component (C) is not particularly limited, and known materials such as benzophenone, anthraquinone, benzoyl, sulfonium salt, diazonium salt, onium salt and the like can be used.

Specifically, benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), N, N-tetraethyl-4,4′-diaminobenzophenone, 4-methoxy-4,4′-dimethyl Aminobenzophenone, α-hydroxyisobutylphenone, 2-ethylanthraquinone, t-butylanthraquinone, 1,4-dimethylanthraquinone, 1-chloroanthraquinone, 2,3-dichloroanthraquinone, 3-chloro-2-methylanthraquinone, 1,2 -Benzoanthraquinone, 2-phenylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, thioxanthone, 2-chlorothioxanthone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethane Aromatic ketone compounds such as -1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one and 2,2-diethoxyacetophenone; benzoin compounds such as benzoin, methylbenzoin and ethylbenzoin; benzoin methyl Benzoin ether compounds such as ether, benzoin ethyl ether, benzoin isobutyl ether and benzoin phenyl ether; benzyl compounds such as benzyl and benzyldimethyl ketal; ester compounds such as β- (acridin-9-yl) (meth) acrylic acid; 9- Acridine compounds such as phenylacridine, 9-pyridylacridine, 1,7-diacridinoheptane; 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5 -Di (m-met Cyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p- Methoxyphenyl) -4,5-diphenylimidazole dimer, 2,4-di (p-methoxyphenyl) 5-phenylimidazole dimer, 2- (2,4-dimethoxyphenyl) -4,5-diphenylimidazole Dimer, 2,4,5-triarylimidazole dimer such as 2- (p-methylmercaptophenyl) -4,5-diphenylimidazole dimer; 2-benzyl-2-dimethylamino-1- ( 4-Morpholinophenyl) -1-butanone; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propane; bis (2, 4,6-trimethylbenzoyl) -phenylphosphine oxide; oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone) and the like. These compounds may be used in combination.

In particular, the component (C) that does not color the adhesive resin composition includes 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- [4- ( Α-hydroxyalkylphenone compounds such as 2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one; bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide Acylphosphine oxide compounds such as bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; Hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) Ropanon) and the like, it is preferable, particularly combinations thereof.

In order to produce a particularly thick sheet (adhesive layer) having a film thickness of about 1.0 × 10 ² μm or more, the component (C) is bis (2,4,6-trimethylbenzoyl) -phenylphosphine. An acyl phosphine oxide compound such as oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, etc. preferable.

Even if content of (C) component in this embodiment is 0.05 mass% or more from a practical viewpoint with respect to the total mass of adhesive resin composition, or 0.1 mass% or more, Good. On the other hand, it is preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 0.5% by mass or less. By setting the content of the component (C) to 5% by mass or less, it is possible to obtain a pressure-sensitive adhesive layer that has a high transmittance and does not have a yellowish hue.

[Other additives]
In addition to the above components (A), (B), and (C), the adhesive resin composition may contain various additives as necessary. As various additives that can be contained, for example, a polymerization inhibitor such as paramethoxyphenol added for the purpose of enhancing the storage stability of the adhesive resin composition, an adhesive layer obtained by photocuring the adhesive resin composition, and the like. An antioxidant such as triphenyl phosphite added for the purpose of increasing heat resistance, a light stabilizer such as HALS (Hindered Amine Light Stabilizer) added for the purpose of increasing the resistance of the adhesive resin composition to light such as ultraviolet rays, Examples include a silane coupling agent that is added to increase the adhesion of the adhesive resin composition to glass or the like.

When the pressure-sensitive adhesive sheet for an image display device is obtained, the pressure-sensitive adhesive layer is a base material layer of a polymer film such as a polyethylene terephthalate film (coating substrate: heavy release separator 3 and the same cover film: light release separator 4). ). At this time, in order to control the peelability between the adhesive layer and the base material layer such as polyethylene terephthalate film, the adhesive resin composition contains a surfactant such as polydimethylsiloxane or fluorine. be able to.

These additives may be used alone or in combination with a plurality of additives. The content of these other additives is usually a small amount compared to the total content of the above (A), (B) and (C), and is generally based on the total mass of the adhesive resin composition. It is about 0.01% by mass to 5% by mass.
The light transmittance of the adhesive layer for light in the visible light region (wavelength: 380 nm to 780 nm) is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. preferable.

As the heavy release separator (second base material layer) 3, for example, a polyester film such as polyethylene terephthalate, a polymer film such as polypropylene and polyethylene is preferable, and among them, a polyethylene terephthalate film (hereinafter referred to as “PET film”) may be used. ) Is more preferable. From the viewpoint of workability, the thickness of the heavy release separator 3 is preferably 50 μm or more, more preferably 60 μm or more, and even more preferably 70 μm or more. From the same viewpoint, it is preferably 2.0 × 10 ² μm or less, more preferably 1.5 × 10 ² μm or less, and further preferably 1.3 × 10 ² μm or less. From the viewpoint of ease of handling and the like, the planar shape of the heavy release separator 3 is larger than the planar shape of the adhesive layer 2, and the outer edge of the heavy release separator 3 protrudes outward from the outer edge of the adhesive layer 2. preferable. The amount by which the outer edge of the heavy release separator 3 protrudes from the outer edge of the adhesive layer 2 is preferably 2 mm or more from the viewpoint of ease of handling, ease of peeling, and adhesion of dust and the like, and is preferably 4 mm or more. It is more preferable. From the same viewpoint, it is preferably 20 mm or less, and more preferably 10 mm or less. When the planar shape of the pressure-sensitive adhesive layer 2 and the heavy release separator 3 is a rectangular shape such as a rectangle, the amount of the outer edge of the heavy release separator 3 protruding from the outer edge of the pressure-sensitive adhesive layer 2 is easy to handle, easy to peel off, From the viewpoint of further reducing adhesion of dust or the like, it is preferably 2 mm or more on at least one side, more preferably 4 mm or more on at least one side, and further preferably 2 mm or more on all sides. It is particularly preferable that the length is 4 mm or more on all sides. From the same viewpoint, the amount of the outer edge of the heavy release separator 3 protruding beyond the outer edge of the pressure-sensitive adhesive layer 2 is preferably 20 mm or less on at least one side, and more preferably 10 mm or less on at least one side. Further, it is more preferably 20 mm or less on all sides, and particularly preferably 10 mm or less on all sides.

As the light release separator (first base material layer) 4, for example, polyester films such as polyethylene terephthalate, polymer films such as polypropylene and polyethylene are preferable, and among these, from the viewpoint of workability, a polyethylene terephthalate film is more preferable. preferable. From the viewpoint of workability, the thickness of the light release separator 4 is preferably 25 μm or more, more preferably 30 μm or more, and further preferably 40 μm or more. From the same viewpoint, it is preferably 1.5 × 10 ² μm or less, more preferably 1.0 × 10 ² μm or less, and further preferably 75 μm or less. The planar shape of the light release separator 4 is larger than the planar shape of the pressure-sensitive adhesive layer 2 from the viewpoint of ease of handling and the like, and it is preferable that the outer edge of the light release separator 4 projects outward from the outer edge of the pressure-sensitive adhesive layer 2. The amount by which the outer edge of the light release separator 4 protrudes from the outer edge of the pressure-sensitive adhesive layer 2 is preferably 2 mm or more, from the viewpoint of ease of handling, ease of peeling, and reduction of adhesion of dust and the like. It is more preferable. From the same viewpoint, it is preferably 20 mm or less, and more preferably 10 mm or less. When the planar shape of the pressure-sensitive adhesive layer 2 and the light release separator 4 is a rectangular shape such as a rectangle, the amount of the outer edge of the light release separator 4 protruding from the outer edge of the pressure-sensitive adhesive layer 2 is 2 mm or more on at least one side. It is preferable that it is 4 mm or more on at least one side, more preferably 2 mm or more on all sides, and particularly preferably 4 mm or more on all sides. From the same viewpoint, it is preferably 20 mm or less on at least one side, more preferably 10 mm or less on at least one side, further preferably 20 mm or less on all sides, and 10 mm on all sides. It is particularly preferred that

The peel strength between the light release separator 4 and the adhesive layer 2 is preferably lower than the peel strength between the heavy release separator 3 and the adhesive layer 2. Thereby, the heavy release separator 3 is less likely to peel from the adhesive layer 2 than the light release separator 4. Further, as will be described later, since the blade B is passed through the adhesive layer 2 toward the heavy release separator 3, the outer edge portion of the adhesive layer 2 is pressed against the heavy release separator 3. Thereby, the heavy release separator 3 becomes more difficult to peel from the adhesive layer 2 than the light release separator 4, and the light release separator 4 can be released before the heavy release separator 3 is peeled off. Therefore, the

separators

3 and 4 can be peeled one by one, and the operation of peeling the

separators

3 and 4 and sticking the adhesive layer 2 to separate adherends can be performed reliably one by one. The peel strength between the heavy release separator 3 and the pressure-sensitive adhesive layer 2 and between the light release separator 4 and the pressure-sensitive adhesive layer 2 can be adjusted, for example, by subjecting the heavy release separator 3 and the light release separator 4 to surface treatment. . Examples of the surface treatment method include a mold release treatment with a silicone compound or a fluorine compound.

<Production Method I (3-layer product) of pressure-sensitive adhesive sheet for image display device>
The pressure-sensitive adhesive sheet 1A described above is manufactured as follows. First, as shown in FIG. 5, a base material film 10 A in which an adhesive layer 2 is formed on a heavy release separator (second base material layer) 3 and a temporary separator 6 is formed on the adhesive layer 2 is prepared. . The temporary separator 6 is, for example, a layer made of the same material as the light release separator 4.

Subsequently, as shown in FIG. 6, the temporary separator 6 and the adhesive layer 2 are cut into a desired shape by a punching device (not shown) provided with a blade B. The punching device may be a crank punching device, a reciprocating punching device, or a rotary punching device. From the viewpoint of peelability of each substrate, a rotary punching device is preferable. In this step, it is preferable that the blade B is passed through the temporary separator 6 and the adhesive layer 2 at a depth reaching the heavy release separator 3 to cut the temporary separator 6 and the adhesive layer 2. Thereby, the notch part 3c is formed in the heavy peeling separator 3, and peeling of the heavy peeling separator 3 from the adhesion layer 2 becomes easy.

Subsequently, the outer portions of the temporary separator 6 and the adhesive layer 2 are removed as shown in FIG. 7, the temporary separator 6 is peeled off from the adhesive layer 2 as shown in FIG. 8, and the adhesive as shown in FIG. A light release separator (first base material layer) 4 is attached to the layer 2. The adhesive sheet 1A is completed through the above steps.

<Image display device>
Next, an image display device manufactured using the adhesive sheet 1A will be described. The pressure-sensitive adhesive layer 2 provided in the pressure-sensitive adhesive sheet 1A can be applied to various image display devices. Examples of the image display device include a plasma display (PDP), a liquid crystal display (LCD), a cathode ray tube (CRT), a field emission display (FED), an organic EL display (OELD), a 3D display, and electronic paper (EP). . The pressure-sensitive adhesive layer 2 of the present embodiment may be used for combining and bonding functional layers having functionality such as an antireflection layer, an antifouling layer, a dye layer, and a hard coat layer of an image display device, and a transparent protective plate. it can.

The antireflection layer may be a layer having an antireflection property with a visible light reflectance of 5% or less, and is a layer treated by a known antireflection method on a transparent substrate such as a transparent plastic film. Can be used.

The antifouling layer is for preventing the surface from getting dirty, and a known layer composed of a fluorine resin or a silicone resin can be used to reduce the surface tension.

The dye layer is used to increase color purity, and is used to reduce unnecessary light when the color purity of light emitted from an image display unit such as a liquid crystal display unit is low. The pigment | dye which absorbs the light of an unnecessary part can be melt | dissolved in resin, and it can form and laminate | stack on base films, such as a polyethylene film and a polyester film.

The hard coat layer is used to increase the surface hardness. As a hard-coat layer, what formed or laminated | stacked acrylic resin, such as urethane acrylate and an epoxy acrylate; base films, such as a polyethylene film, can be used, for example. Similarly, in order to increase the surface hardness, it is also possible to use a hard coat layer formed or laminated on a transparent protective plate such as glass, acrylic resin or polycarbonate.

The adhesive layer 2 can be used by being laminated on a polarizing plate. In this case, it can also laminate | stack on the visual recognition surface side of a polarizing plate, and can also laminate | stack on the opposite side.

When used on the viewing surface side of the polarizing plate, an antireflection layer, an antifouling layer and a hard coat layer can be laminated on the viewing surface side of the adhesive layer 2 and used between the polarizing plate and the liquid crystal cell. In this case, a functional layer can be laminated on the viewing surface side of the polarizing plate.

In the case of such a laminate, the adhesive layer 2 can be laminated using a roll laminate, a vacuum bonding machine, or a single wafer bonding machine.

The adhesive layer 2 is preferably disposed between the image display unit of the image display device and the transparent protective plate on the front side of the viewing side, at an appropriate position on the viewing side. Specifically, it is preferably applied between the image display unit and the transparent protective plate.

In addition, in an image display device in which a touch panel is combined with an image display unit, it is preferable to apply between the touch panel and the image display unit or between the touch panel and the transparent protective plate. As long as the adhesive layer 2 in the form is applicable, the position is not limited to the above-described position.

Hereinafter, a liquid crystal display device which is one of image display devices will be described in detail with reference to FIGS. 10 and 11 as an example.

FIG. 10 is a side sectional view schematically showing one embodiment of the liquid crystal display device of the present invention. 10 includes an image display unit 7 in which a backlight system 50, a polarizing plate 22, a liquid crystal display cell 12, and a polarizing plate 20 are laminated in this order, and a polarizing plate on the viewing side of the liquid crystal display device. The transparent resin layer 32 provided on the upper surface 20 and a transparent protective plate (protective panel) 40 provided on the surface thereof. A step 60 provided on the surface of the transparent protective plate 40 is embedded with a transparent resin layer 32. The transparent resin layer 32 basically corresponds to the adhesive layer of this embodiment.

FIG. 11 is a side cross-sectional view schematically showing a liquid crystal display device equipped with a touch panel, which is an embodiment of the liquid crystal display device of the present invention. The liquid crystal display device shown in FIG. 11 includes an image display unit 7 in which a backlight system 50, a polarizing plate 22, a liquid crystal display cell 12, and a polarizing plate 20 are laminated in this order, and a polarizing plate on the viewing side of the liquid crystal display device. 20, a transparent resin layer 32 provided on the top surface, a touch panel 30 provided on the top surface of the transparent resin layer 32, a transparent resin layer 31 provided on the top surface of the touch panel 30, and a transparent protective plate provided on the surface thereof 40. The step 60 provided on the surface of the transparent protective plate 40 is embedded with the transparent resin layer 31. The transparent resin layer 31 and the transparent resin layer 32 basically correspond to the adhesive layer of this embodiment.

In the liquid crystal display device of FIG. 11, the transparent resin layer is interposed between the image display unit 7 and the touch panel 30 and between the touch panel 30 and the transparent protective plate 40 having the step 60. The transparent resin layer only needs to be interposed in at least one of these, and in particular, when the adhesive layer of the present embodiment is used, it is preferably interposed between the touch panel 30 and the transparent protective plate 40 having the step 60. When the touch panel is on-cell, the touch panel and the liquid crystal display cell are integrated. As a specific example, the liquid crystal display cell 12 of the liquid crystal display device of FIG. 10 is replaced with an on-cell.
In recent years, development of a liquid crystal display cell incorporating a touch panel function, called an in-cell type touch panel, is in progress. The liquid crystal display device provided with such a liquid crystal display cell is composed of a transparent protective plate, a polarizing plate, and a liquid crystal display cell (liquid crystal display cell with a touch panel function), and has a photocurable adhesive resin according to the present invention. The composition can also be suitably used for a liquid crystal display device employing such an in-cell type touch panel.

According to the liquid crystal display device shown in FIGS. 10 and 11, since the adhesive layer of the present embodiment is provided as the

transparent resin layer

31 or 32, it has impact resistance, a double image and a clear and high contrast image. can get.

The liquid crystal display cell 12 can be made of a liquid crystal material well known in the art. Further, depending on the control method of the liquid crystal material, it is classified into a TN (Twisted Nematic) method, a STN (Super-twisted nematic) method, a VA (Virtual Alignment) method, an IPS (In-Place-Switching) method, etc. Then, it may be a liquid crystal display cell using any control method.

As the

polarizing plates

20 and 22, a polarizing plate common in this technical field can be used. The surfaces of these polarizing plates may be subjected to treatments such as antireflection, antifouling, and hard coat. Such surface treatment may be performed on one side of the polarizing plate or on both sides thereof.

As the touch panel 30, those commonly used in this technical field can be used.

The

transparent resin layer

31 or 32 can be formed with a thickness of 0.02 mm to 3 mm, for example. In particular, in the curable resin composition of the present embodiment, by making the film thickness about 1.0 × 10 ² μm or more, a more excellent effect can be exhibited, and 1.0 × 10 ² It can be suitably used when forming the

transparent resin layer

31 or 32 of μm or more and 5.0 × 10 ² μm or less.

As the transparent protective plate 40, a general optical transparent substrate can be used. Specific examples thereof include inorganic plates such as glass substrates and quartz plates; plastic substrates such as acrylic resin substrates, polycarbonate plates and cycloolefin polymer plates; resin sheets such as thick polyester sheets. When high surface hardness is required, a glass substrate and an acrylic resin substrate are preferable, and a glass substrate is more preferable. The surface of these transparent protective plates may be subjected to treatments such as antireflection, antifouling, and hard coat. Such surface treatment may be performed on one side of the transparent protective plate or on both sides. A plurality of transparent protective plates can be used in combination.

The backlight system 50 is typically composed of reflecting means such as a reflector and illumination means such as a lamp.

<Image Display Device Manufacturing Method I (Three-layer Product)>
The pressure-sensitive adhesive sheet 1A is used as follows in assembling an image display device. First, as shown in FIG. 12, the light release separator 4 is peeled from the pressure-sensitive adhesive sheet 1 A to expose the pressure-sensitive adhesive surface 2 d of the pressure-sensitive adhesive layer 2. Subsequently, as shown in FIG. 13, the adhesive surface 2 d of the adhesive layer 2 is attached to the adherend A 1 and pressed with a roller R or the like. At this time, the step 60 provided on the surface of the adherend A 1 is embedded by the adhesive layer 2. The adherend A1 is, for example, an image display unit, a transparent protective plate, or a touch panel. Subsequently, as shown in FIG. 14, the heavy release separator 3 is peeled from the adhesive layer 2 to expose the adhesive surface 2 e of the adhesive layer 2. Subsequently, as shown in FIG. 15, the adhesive surface 2 e of the adhesive layer 2 is attached to the adherend A 2 and subjected to a heating and pressurizing process (autoclave process). The adherend A2 is, for example, an image display unit, a transparent protective plate, or a touch panel. In this way, the adherends can be bonded together via the adhesive layer 2. Note that the heat and pressure treatment conditions at this time are a temperature of 20 ° C. to 80 ° C. and a pressure of 0.2 MPa to 0.8 MPa.

Through the above steps, the adhesive layer 2 is disposed between the adherend A1 and the adherend A2. In particular, the adhesive layer 2 is preferably used by being disposed between the transparent protective plate and the touch panel, or between the touch panel and the image display unit.

10 described above can be manufactured by obtaining a laminate by interposing the adhesive layer of the present embodiment between the image display unit and the transparent protective plate. That is, in the image display device illustrated in FIG. 10, the adhesive layer of the present embodiment can be laminated on the upper surface of the polarizing plate 20 by a laminating method.

The above-described liquid crystal display device of FIG. 11 is manufactured by obtaining a laminate by interposing the adhesive layer of the present embodiment between the image display unit and the touch panel, or between the touch panel and the transparent protective plate. Can do.

[Second Embodiment]
<Adhesive sheet II for image display device (4-layer product)>
The pressure-sensitive adhesive sheet for an image display device of the present embodiment was further laminated on the film-like pressure-sensitive adhesive layer, the first and second base material layers laminated so as to sandwich the pressure-sensitive adhesive layer, and the second base material layer. A carrier layer, and the outer edges of the first base material layer and the carrier layer protrude outward from the outer edge of the adhesive layer.

That is, as shown in FIG. 16 and FIG. 17, the pressure-sensitive adhesive sheet 1 B according to this embodiment includes a transparent film-like pressure-sensitive adhesive layer 2 and a light release separator 4 (first film) that is laminated so as to sandwich the pressure-sensitive adhesive layer 2. ) And a heavy release separator 3 (second base material layer), and a carrier film 5 (carrier layer) further laminated on the heavy release separator 3.

The outer edge 5 a of the carrier film 5 projects outward from the outer edge 2 a of the adhesive layer 2. Thereby, the carrier film 5 can be easily peeled from the second base material layer by pinching the outer edge portion of the carrier film 5 protruding outward. Moreover, it is preferable that the outer edge 5 a of the carrier film 5 projects outward from the outer edge 4 a of the light release separator 4. Thereby, since the outer edge part of the carrier film 5 becomes easier to pinch, the carrier film 5 can be peeled off more easily. The amount by which the outer edge 5a of the carrier film 5 protrudes from the outer edge 4a of the light release separator 4 is preferably 0.5 mm or more from the viewpoint of ease of handling, ease of peeling, and adhesion of dust and the like. It is preferable that it is 1 mm or more. From the same viewpoint, the amount by which the outer edge 5a of the carrier film 5 protrudes from the outer edge 4a of the light release separator 4 is preferably 10 mm or less, and more preferably 5 mm or less. When the planar shape of the carrier film 5, the adhesive layer 2, the heavy release separator 3, and the light release separator 4 is a rectangular shape such as a rectangle, the outer edge 5 a of the carrier film 5 protrudes beyond the outer edge 4 a of the light release separator 4. The amount is preferably 0.5 mm or more on at least one side, more preferably 1 mm or more on at least one side, further preferably 0.5 mm or more on all sides, and all sides Is particularly preferably 1 mm or more. From the same viewpoint, the amount by which the outer edge 5a of the carrier film 5 protrudes from the outer edge 4a of the light release separator 4 is preferably 10 mm or less on at least one side, and 5 mm or less on at least one side. More preferably, it is more preferably 10 mm or less on all sides, and particularly preferably 5 mm or less on all sides.

Since the heavy release separator 3 is protected by the carrier film 5 until the last step, the surface of the heavy release separator 3 is less damaged. Thereby, the damage | wound of the adhesion layer 2 can be visually recognized easily, and can be easily excluded before sticking the adhesion layer 2 which the damage | wound has produced on the to-be-adhered thing.

The carrier film 5 is, for example, a polymer film such as polyethylene terephthalate, polypropylene, polyethylene, or polyester, and among them, a polyethylene terephthalate film is preferable. From the viewpoint of workability, the thickness of the carrier film 5 is preferably 15 μm or more, more preferably 20 μm or more, and particularly preferably 25 μm or more. From the same viewpoint, the thickness of the carrier film 5 is preferably 1.0 × 10 ² μm or less, more preferably 80 μm or less, and further preferably 20 μm or more and 50 μm or less.

The peel strength between the light release separator 4 and the adhesive layer 2 is lower than the peel strength between the heavy release separator 3 and the adhesive layer 2. The peel strength between the carrier film 5 and the heavy release separator 3 is lower than the peel strength between the heavy release separator 3 and the adhesive layer 2. Here, the peel strength between the carrier film 5 and the heavy release separator 3 is more preferably lower than the peel strength between the light release separator 4 and the pressure-sensitive adhesive layer 2, but even if high, the effect of the present application is impaired. There is no.

The peel strength between the carrier film 5 and the heavy release separator 3 is adjusted by, for example, the type and thickness of the adhesive layer or the pressure-sensitive adhesive layer formed between the carrier film 5 and the heavy release separator 3. Examples of the type of adhesive or pressure-sensitive adhesive layer formed between the carrier film 5 and the heavy release separator 3 include an adhesive or pressure-sensitive adhesive layer such as an acrylic adhesive. From the viewpoint of workability, the thickness of the adhesive layer or the pressure-sensitive adhesive layer formed between the carrier film 5 and the heavy release separator 3 is preferably 0.1 μm or more, and more preferably 1 μm or more. From the same viewpoint, the thickness of the adhesive layer or the pressure-sensitive adhesive layer formed between the carrier film 5 and the heavy release separator 3 is preferably 10 μm or less, and more preferably 5 μm or less.

Thus, according to the pressure-sensitive adhesive sheet 1B of the present embodiment, the

separators

3 and 4 and the carrier film 5 can be reliably peeled in a predetermined order without any defective peeling while protecting the pressure-sensitive adhesive layer 2.

<Manufacturing method II of adhesive sheet for image display device (4-layer product)>
The pressure sensitive adhesive sheet 1B is manufactured as follows. First, as shown in FIG. 18, a base material film 10 B in which a heavy release separator 3, an adhesive layer 2, and a temporary separator 6 are sequentially laminated on a carrier film 5 is prepared. The temporary separator 6 is, for example, a layer made of the same material as the light release separator 4.

Subsequently, the temporary separator 6, the adhesive layer 2, and the heavy release separator 3 are cut into desired shapes by a punching device (not shown) provided with the blade B. In this step, as shown in FIG. 19, it is preferable to pass the blade B through the temporary separator 6, the adhesive layer 2, and the heavy release separator 3 at a depth reaching the carrier film 5. Thereby, the notch part 5c is formed in the surface 5b by the side of the adhesion layer 2 of the carrier film 5. FIG. Thus, the adhesive layer 2 and the heavy release separator 3 can be completely cut by allowing the blade B to reach the carrier film 5 from the temporary separator 6.

Subsequently, the outer portions of the temporary separator 6, the adhesive layer 2, and the heavy release separator 3 are removed as shown in FIG. At this time, the outer edge 3a of the heavy release separator 3 is substantially flush with the outer edge 5a of the carrier film 5 so that the outer edge of the carrier film 5 does not protrude outward from the outer edge 3a of the heavy release separator 3 as shown in FIG. Preferably it is one. That is, only the outer part of the temporary separator 6 and the adhesive layer 2 is removed, and the outer part of the heavy release separator 3 is left on the carrier film 5 without being removed. The heavy release separator 3 after cutting is attached to the carrier film 5 as it is. It is preferable that the Thereby, the problem that the surface-exposed carrier film 5 adheres to other portions can be effectively prevented.

After removing the outer portions of the temporary separator 6, the adhesive layer 2 and the heavy release separator 3 as shown in FIG. 20, the temporary separator 6 is subsequently released from the adhesive layer 2 as shown in FIG. A light release separator 4 is affixed to the adhesive layer 2 as shown. The pressure-sensitive adhesive sheet 1B of this embodiment is completed through the above steps. Thus, if the film is cut so that the outer edge 3a of the heavy release separator 3 is substantially flush with the outer edge 2a of the pressure-sensitive adhesive layer 2, the light release separator 4 and the heavy release separator 3 are easily peeled off. Thus, the light release separator 4 can be more easily peeled before the heavy release separator 3 is released. Furthermore, since the position of the outer edge of the adhesive layer 2 becomes clear because the outer edge of the heavy release separator 3 and the outer edge 2a of the adhesive layer 2 are aligned, the alignment between the adhesive layer 2 and the adherend becomes easy.

<Production Method II of Image Display Device (4-Layer Product)>
The pressure-sensitive adhesive sheet 1B of the present embodiment is the same as the pressure-sensitive adhesive sheet 1A of the first embodiment except that the carrier film 5 is first peeled off from the heavy release separator 3 as shown in FIG. Can be used.

The preferred embodiments of the present invention have been described above, but the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

Hereinafter, the present invention will be described by way of examples. In this example, the pressure-sensitive adhesive sheets according to the first embodiment and the second embodiment are produced, but the present invention is not limited to these examples.

Synthesis Example 1 (Synthesis of acrylic acid derivative polymer (A-1))
[ISTA / HEA = 8/2]
96.0 g of isostearyl acrylate (manufactured by Hitachi Chemical Co., Ltd., trade name “FA-117A”) and 2-hydroxy as an initial monomer in a reaction vessel equipped with a cooling tube, a thermometer, a stirring device, a dropping funnel and a nitrogen introduction tube Weigh 24.0 g of ethyl acrylate (trade name “HEA”, manufactured by Osaka Organic Chemical Industry Co., Ltd.) and 150.0 g of methyl ethyl ketone, and heat from 25 ° C. to 80 ° C. for 15 minutes while substituting nitrogen with an air volume of 100 ml / min. did. Thereafter, while maintaining the temperature at 80 ° C., 24.0 g of isostearyl acrylate and 6.0 g of 2-hydroxyethyl acrylate were used as additional monomers, and t-butylperoxy-2-ethylhexanoate (day) was used. A solution in which 5.0 g (trade name “Perbutyl O” manufactured by Oil Co., Ltd.) was dissolved was prepared, and this solution was dropped over 2 hours. After completion of dropping, the reaction was further continued for 2 hours.
Subsequently, methyl ethyl ketone was distilled off to obtain a copolymer resin of isostearyl acrylate and 2-hydroxyethyl acrylate (weight average molecular weight 3.0 × 10 ⁵ ).

Synthesis Example 2 (Synthesis of acrylic acid derivative polymer (A-2))
[2EHA / HEA = 7/3]
Weighed 84.0 g of 2-ethylhexyl acrylate, 36.0 g of 2-hydroxyethyl acrylate, and 150.0 g of methyl ethyl ketone as initial monomers in a reaction vessel equipped with a condenser, thermometer, stirrer, dropping funnel and nitrogen inlet tube. Heating was performed from 25 ° C. to 80 ° C. in 15 minutes while replacing the nitrogen with an air volume of 100 ml / min. Thereafter, while maintaining the temperature at 80 ° C., 21.0 g of 2-ethylhexyl acrylate and 9.0 g of 2-hydroxyethyl acrylate were used as additional monomers, and t-butylperoxy-2-ethylhexanoate 5 A solution in which 0.0 g was dissolved was prepared, and this solution was added dropwise over 2 hours. After completion of the dropwise addition, the reaction was allowed to proceed for 2 hours.
Subsequently, methyl ethyl ketone was distilled off to obtain a copolymer resin of 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate (weight average molecular weight 1.8 × 10 ⁵ ).

Synthesis Example 3 (Synthesis of polyurethane diacrylate (D-1))
285.3 g of polypropylene glycol (number average molecular weight 2.0 × 10 ³ ), unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone (HEA) in a reaction vessel equipped with a condenser, thermometer, stirrer, dropping funnel and air inlet tube Of 2 mol of caprolactone, CH ₂ ═CHCOO (CH ₂ ) ₂ O [CO (CH ₂ ) ₅ O] nH, manufactured by Daicel Corporation, trade name “Placcel FA2D”) 24.5 g, p-methoxy as a polymerization inhibitor Taking 0.13 g of phenol and 0.5 g of dibutyltin dilaurate (trade name “EMBILIZER L-101”, manufactured by Tokyo Fine Chemical Co., Ltd.) as a catalyst, flowing air at a flow rate of 100 ml / min. Heated to ° C. Thereafter, 39.6 g of isophorone diisocyanate (manufactured by Sumika Bayer Urethane Co., Ltd., trade name “Desmodur 1”) was added dropwise over 2 hours while maintaining the temperature at 75 ° C. After completion of the dropwise addition, the reaction was allowed to proceed for 6 hours.
As a result of IR measurement (measurement wave number: 2270 cm ⁻¹ ), it was confirmed that the isocyanate group had disappeared, and the reaction was terminated. Polypropylene glycol and isophorone diisocyanate were used as repeating units, and (meth) acryloyl groups were present at both ends. Polyurethane acrylate (weight average molecular weight 3.0 × 10 ⁴ ) was obtained.

Synthesis Example 4 (Synthesis of polyurethane diacrylate (D-2))
285.3 g of polypropylene glycol (number average molecular weight 2.0 × 10 ³ ), unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone (stock) in a reaction vessel equipped with a condenser, thermometer, stirrer, dropping funnel and air inlet tube Company Daicel, trade name “PLAXEL FA2D”) 37 g, p-methoxyphenol 0.13 g as a polymerization inhibitor and 0.5 g of dibutyltin dilaurate as a catalyst are taken, and air flows at a flow rate of 100 ml / min in 15 minutes. It heated from normal temperature (25 degreeC) to 75 degreeC. Thereafter, 39.6 g of isophorone diisocyanate was added dropwise over 2 hours while maintaining the temperature at 75 ° C. After completion of the dropwise addition, the reaction was allowed to proceed for 6 hours.
As a result of IR measurement (measurement wave number: 2270 cm ⁻¹ ), it was confirmed that the isocyanate group had disappeared, and the reaction was terminated. Polypropylene glycol and isophorone diisocyanate were used as repeating units, and (meth) acryloyl groups were present at both ends. Polyurethane acrylate (weight average molecular weight 5.0 × 10 ³ ) was obtained.

The weight average molecular weight is measured using gel permeation chromatography using tetrahydrofuran (THF) as a solvent, and converted using a standard polystyrene calibration curve using the following apparatus and measurement conditions. It is the determined value. In preparing the calibration curve, a 5-sample set (PStQuick MP-H, PStQuick B [manufactured by Tosoh Corporation, trade name]) was used as standard polystyrene.

Device: High-speed GPC device HLC-8320GPC (detector: differential refractometer) (trade name, manufactured by Tosoh Corporation)
Solvent: Tetrahydrofuran (THF)
Column: Column TSKGEL SuperMultipore HZ-H (trade name, manufactured by Tosoh Corporation)
Column size: Column length is 15 cm, column inner diameter is 4.6 mm
Measurement temperature: 40 ° C
Flow rate: 0.35 ml / min Sample concentration: 10 mg / THF 5 ml
Injection volume: 20 μl

The following each component used as the raw material of an adhesive resin composition was prepared.
Component A: Acrylic acid derivative polymer (A-1) to (A-2)
Component B: Isostearyl acrylate (ISTA)
: 2-ethylhexyl acrylate (2EHA)
: 4-hydroxybutyl acrylate (4HBA)
: N, N-dimethylacrylamide (DMAA)
: 2-ethylhexyl methacrylate (EHMA)
: Acryloylmorpholine (ACMO)
Component D: Polyurethane diacrylate (D-1) to (D-2)
: Polybutane acrylate (manufactured by Negami Kogyo Co., Ltd., HCCN-001SG1)
: Polybutadiene acrylate (manufactured by Negami Kogyo Co., Ltd., HCCN-001SPG)
Component C: 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Japan Ltd., hereinafter I-184)

<Example 1>
[Preparation I of adhesive sheet 1A]
Using the polyethylene terephthalate having a thickness of 75 μm (made by Fujimori Kogyo Co., Ltd.) as the heavy release separator 3 and the polyethylene terephthalate having a thickness of 50 μm (made by Fujimori Kogyo Co., Ltd.) as the light release separator 4 and the temporary separator 6, the following (I) to 1A of adhesive sheets were produced in the procedure of (VI).

(A1) (Meth) acrylic acid derivative polymer (I) Acrylic acid derivative polymer (A-1) 35.0 g, (A2) component (meth) acrylic having one (meth) acryloyl group in the molecule As acid derivative monomers, 39.0 g of isostearyl acrylate (ISTA), 10.0 g of 2-ethylhexyl acrylate (2EHA) and 5.0 g of 2-ethylhexyl methacrylate (EHMA), 10.0 g of N, N-dimethylacrylamide (DMAA), (B) 0.5 g of polybutane acrylate (HCCN-001SG1) containing a structural unit derived from a butane polymer having a (meth) acryloyl group or a butadiene polymer having a (meth) acryloyl group, (C) 1-Hydroxycyclohexyl as a component photopolymerization initiator Weigh 0.5 g of Ruphenylketone (I-184) (trade name “Irgacure-184”, manufactured by BASF Japan Ltd.), and stir and mix them to obtain a liquid adhesive resin composition at room temperature (25 ° C.). I got a thing.

(II) After coating this adhesive resin composition on the heavy release separator 3 to form a coating film, a temporary separator 6 is laminated on the adhesive layer 2, and an ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd.). Was used to irradiate ultraviolet rays (2.0 × 10 ³ mJ / cm ² ) to obtain an adhesive sheet having the adhesive layer 2 sandwiched between the heavy release separator 3 and the temporary separator 6. The adhesive layer 2 was coated by adjusting the thickness to 1.5 × 10 ² μm.

(III) The heavy release separator 3, the adhesive layer 2, and the temporary separator 6 were cut with a rotary blade having a diameter of 72 mm so as to be 220 mm × 180 mm.

(IV) The adhesive layer 2 and the temporary separator 6 were cut with a rotary blade having a diameter of 72 mm so as to be 205 mm × 160 mm. At this time, both sides on the long side of the heavy release separator 3 protrude 7.5 mm from both sides on the long side of the adhesive layer 2, and both sides on the short side of the heavy release separator 3 are adhesive layer 2. It cut | disconnected so that it might protrude from both sides of the short side of 10 mm. The cutting of (III) and (IV) was performed using a rotary punching device.

(V) The temporary separator 6 was peeled off, and a 215 mm × 170 mm light release separator 4 was laminated on the adhesive layer 2. Thus, 1 A of adhesive sheets for image display apparatuses were obtained. At this time, both sides on the long side of the light release separator 4 protrude 5 mm from both sides on the long side of the adhesive layer 2, and both sides on the short side of the light release separator 4 are short sides of the adhesive layer 2. Lamination was carried out so as to protrude 5 mm from both sides.

<Examples 2 to 6 and Comparative Examples 1 to 3>
An adhesive sheet 1A for an image display device was obtained in the same manner as in Example 1 except that the blending conditions were as shown in Table 1.

[Various evaluations]
The following (1) to (3) were evaluated for the pressure-sensitive adhesive sheets obtained in each Example and Comparative Example.

(1) Optical characteristics The prepared pressure-sensitive adhesive sheet was left in an environment of 60 ° C. and 95% RH for 96 hours. Next, the produced pressure-sensitive adhesive sheet was cut into dimensions of 40 mm in width and 100 mm in length, and a polyethylene terephthalate film on one side of the pressure-sensitive adhesive sheet was placed on a glass substrate (soda lime glass) having dimensions of 50 mm × 100 mm × 3 mm (thickness). It peeled and it bonded using the hand roller (25 degreeC, load: 500gf). Next, the polyethylene terephthalate film on the opposite surface of the pressure-sensitive adhesive sheet was peeled off, and the pressure-sensitive adhesive layer surface was measured as the light source side.
(A) Measurement of turbidity (haze) Measured according to JIS K 7361 using a turbidimeter (Nippon Denshoku Industries Co., Ltd., NHD-2000).
(2) Dielectric constant measurement After irradiating the produced adhesive sheet with ultraviolet rays at 2.0 × 10 ³ mJ / cm ² using an ultraviolet irradiation device, the adhesive sheet was cut into dimensions of 50 mm in width and 50 mm in length, and one side of the adhesive sheet The glossy side of a 100 mm × 100 mm × 18 μm (thickness) copper foil (trade name “SLP-18”, manufactured by Nippon Electrolytic Co., Ltd.) was laminated so that the adhesive sheet did not protrude. Next, a 20 mm x 20 mm x 18 μm (thickness) size copper foil (made by Nippon Electrolytic Co., Ltd., trade name “SLP-18”) is pasted on the opposite side of the adhesive sheet so that the adhesive sheet does not protrude. Combined. A terminal is brought into contact with a substantially central portion of each of a copper foil having a size of 100 mm × 100 mm and a copper foil having a size of 20 mm × 20 mm, and the dielectric at 23 ° C. and 100 KHz is measured by a dielectric constant measuring apparatus (ACR Technologies ECR, LCR meter E4980). The rate was measured.
The measurement results of each example and comparative example are summarized in Table 1.

When a compound having a bifunctional (meth) acryloyl group is not used as a structural unit derived from the butane (butadiene) polymer of the component (B) as in Comparative Examples 1 to 3, the dielectric constant increases and haze increases. May be higher. When isostearyl acrylate (ISTA) is used as a (meth) acrylic acid derivative monomer having one (meth) acryloyl group in the molecule as in (A2) as in Comparative Examples 1 and 2, comparison without using it The dielectric constant is lower than in Example 3.
On the other hand, as shown in Examples 1 to 6, (A) component (A1) (meth) acrylic acid derivative polymer and (A2) (meth) acryloyl group (meth) having one in the molecule When both a compound having an acrylic acid derivative monomer and a compound containing a structural unit derived from a (B) component butane polymer having a (meth) acryloyl group or a butadiene polymer having a (meth) acryloyl group are contained The dielectric sheet has a low dielectric constant and a low haze value after being left in a high-temperature and high-humidity environment.

<Example 7>
[Preparation of adhesive sheet 1B (4-layer product)]

(I) A liquid adhesive resin composition was obtained in the same manner as in Example 1.
(II) After coating this adhesive resin composition on one surface of the heavy release separator 3 to form a coating film, the temporary separator 6 is laminated on the adhesive layer 2 and irradiated with ultraviolet rays (2.0 × 10 ³ mJ / cm ² ), and thereafter, an acrylic adhesive (Hitalex K-6040 (trade name), manufactured by Hitachi Chemical Co., Ltd.) is laminated on the other surface of the heavy release separator 3 A carrier film 5 was laminated.
(III) The heavy release separator 3, the adhesive layer 2, the temporary separator 6 and the carrier film 5 were cut so as to be 220 mm × 180 mm.
(IV) The pressure-sensitive adhesive layer 2, the heavy release separator 3 and the temporary separator 6 were cut with a rotary blade having a diameter of 72 mm so as to be 205 mm × 160 mm. A rotary punching device was used for cutting. At this time, both long sides of the carrier film 5 protrude 7.5 mm from both long sides of the adhesive layer 2, and both short sides of the carrier film 5 are short of the adhesive layer 2. It cut | disconnected so that it might protrude 10 mm from both sides of a side.
(V) The temporary separator 6 was peeled off, and a 215 mm × 170 mm light release separator 4 was laminated on the adhesive layer 2. Thus, the adhesive sheet 1B for image display apparatuses was obtained. At this time, both sides on the long side of the light release separator 4 protrude 5 mm from both sides on the long side of the adhesive layer 2, and both sides on the short side of the light release separator 4 are short sides of the adhesive layer 2. Lamination was carried out so as to protrude 5 mm from both sides.

When the same evaluation as described above was performed on the pressure-sensitive adhesive sheet 1B for an image display device, a pressure-sensitive adhesive sheet having a desired shape could be produced, and the optical characteristics and dielectric constant were excellent as in Example 1. .

According to the present invention, it is possible to produce an adhesive sheet for an image display device that is excellent in optical characteristics after being left in a low dielectric constant and high temperature and high humidity environment. A device in which such an adhesive layer is incorporated not only prevents the sensitivity of the touch panel from being lowered, but also prevents the visibility from being lowered. Therefore, the adhesive sheet of the present invention is suitable for use in an image display apparatus. In particular, it is extremely useful as a sheet material used when filling a space between an information input device such as a touch panel and a transparent protective plate.

DESCRIPTION OF SYMBOLS 1A ... Adhesive sheet (3 layer product), 1B ... Adhesive sheet (4 layer product), 2 ... Adhesive layer, 3 ... Heavy release separator (2nd base material layer), 4 ... Light release separator (1st base material) Layer), 5 ... carrier film, 6 ... temporary separator, 2a, 3a, 4a, 5a ... outer edge, 3b, 5b ... adhesive layer side surface, 3c, 5c ... notch, 2d, 2e ... adhesive surface, 10A ... Base material film (3-layer product), 10B: Base material film (4-layer product), B ... Blade, R ... Roller, 40 ... Transparent protective plate (glass or plastic substrate), 7 ... Image display unit, 12 ... Liquid crystal display Cell, 20, 22 ... Polarizing plate, 30 ... Touch panel, 31, 32 ... Transparent resin layer, 50 ... Backlight system, 60 ... Step part (step), 100 ... Jig.

Claims

(A) a structural unit derived from an alkyl (meth) acrylate having 4 to 18 carbon atoms in the alkyl group, (B) a structural unit derived from a butane (butadiene) polymer, and (C) a photopolymerization initiator. An adhesive sheet for an image display device having an adhesive layer.
The said (A) component contains the (meth) acrylic-acid-type derivative monomer which has one (A1) (meth) acrylic-acid-type derivative polymer and (A2) (meth) acryloyl group in a molecule | numerator. Adhesive sheet for image display devices.
The pressure-sensitive adhesive sheet for an image display device according to claim 1 or 2, wherein the component (B) includes a compound having a bifunctional (meth) acryloyl group.
The pressure-sensitive adhesive sheet for an image display device according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer has a thickness of 50 µm or more and 5.0 × 10 2 µm or less.
The pressure-sensitive adhesive sheet for an image display device according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer has a dielectric constant of 23 ° C of 3.0 or less at a measurement frequency of 100 kHz.
6. The pressure-sensitive adhesive sheet for an image display device according to claim 1, wherein the pressure-sensitive adhesive layer has a haze of 1.0% or less after being left in an environment of 60 ° C. and 95% RH for 96 hours.
The pressure-sensitive adhesive sheet for an image display device according to any one of claims 1 to 6, further comprising first and second base material layers laminated so as to sandwich the pressure-sensitive adhesive layer.
The carrier layer further laminated on the second base material layer, and the outer edges of the first base material layer and the carrier layer project outward from the outer edge of the adhesive layer. Adhesive sheet for image display devices.
A step of bonding adherends together to obtain a laminated body through an adhesive layer provided in the adhesive sheet for an image display device according to any one of claims 1 to 8, and the laminated body at 20 ° C to 80 ° C A method for manufacturing an image display device, comprising: a step of heat-pressing under conditions of 0 ° C. and 0.2 MPa to 0.8 MPa; and a step of irradiating the adhesive layer with ultraviolet rays.
10. The method for manufacturing an image display device according to claim 9, wherein the adherend is at least two types selected from a transparent protective plate, a touch panel, and an image display unit.
An image display device having at least two types selected from an image display unit, a touch panel, and a transparent protective plate, and the adhesive layer, and obtained by the process according to claim 9.
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for an image display device according to any one of claims 1 to 6, comprising an image display unit and a transparent protective plate, and interposed between the image display unit and the transparent protective plate. Or a transparent resin layer that is a cured product thereof.
The pressure-sensitive adhesive sheet for an image display device according to any one of claims 1 to 6, comprising an image display unit, a touch panel, and a transparent protective plate, and interposed between the touch panel and the transparent protective plate. And a transparent resin layer that is a cured product thereof.
The apparatus includes at least one step portion that forms a step between an adherend selected from a transparent protective plate, a touch panel, or an image display unit and a transparent resin layer that is an adhesive layer or a cured product thereof. 14. The image display device according to 13.