JP2017025211A - Adhesive sheet for photocurable image display device, manufacturing method of image display device and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive sheet for photocurable image display device excellent in embedding properties into steps even when the steps formed on an adherend are high, excellent in adhesiveness and visibility, capable of being provided in a low temperature process of less than 45°C without whitening in a constant temperature and constant humidity test after laminating sheets, a manufacturing method of an image display device using the same and the image display device.SOLUTION: There is provided an adhesive sheet for photocurable image display device having an adhesive layer containing (A) a copolymer using a vinyl compound with an aromatic group and (meth)acrylic acid alkyl ester, (B) a compound having an ethylenic unsaturated bind, (C) a compound having a hydrophilic group and (D) a photoinitiator with the content of the (C) component of 5 to 25 mass% based on total amount of the adhesive layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure-sensitive adhesive sheet for a photocurable image display device, a method for manufacturing the image display device, and an image display device.

  In recent years, the gap between the transparent protective plate or the information input device (for example, touch panel) and the display surface of the image display unit or the gap between the transparent protective plate and the information input device in the image display device is compared with air. In addition, a method for improving the light transmission and suppressing the decrease in brightness and contrast of the image display device by replacing the transparent protective plate, the information input device and the display surface of the image display unit with a transparent material having a refractive index close to the display surface is proposed. (For example, Patent Document 1). FIG. 23 shows a cross-sectional view of a liquid crystal display device as an example of an image display device. The liquid crystal display device with a built-in touch panel is composed of a transparent protective plate (glass or plastic substrate) D1, a touch panel D2, a polarizing plate D3, and a liquid crystal display cell D4. In order to improve visibility, an adhesive layer (transparent resin layer) D5 is provided between the transparent protective plate and the touch panel, and an adhesive layer (transparent resin layer) D6 is provided between the touch panel and the polarizing plate. Sometimes.

  By the way, the information input device and the image display unit need to be provided with input / output wiring at the peripheral portion thereof. Generally, a frame-like decorative portion D7 is provided by printing or the like on the peripheral portion of the transparent protective plate so that these wirings are not visible from the transparent protective plate side (see FIG. 24, 19 (frame in FIG. 1 of Patent Document 1). Pattern) etc.). In order to eliminate the level difference caused by these decorative portions, for example, a film-like pressure-sensitive adhesive may be used as the pressure-sensitive adhesive that bonds the transparent protective plate. In order to embed in the vicinity of the step without a gap, the film-like pressure-sensitive adhesive is required to be embedded in the step. In recent years, various film-like pressure-sensitive adhesives for improving the embedding property in such steps have been studied (for example, Patent Document 2, Patent Document 3, and Patent Document 4).

JP 2008-83491 A JP 2010-90204 A International Publication No. 2012/032995 Japanese Patent Application No. 2014-158801

  However, as a result of the examination by the present inventors, the film-like pressure-sensitive adhesive D9 as described in Patent Document 2 does not have a sufficient level difference embedding property when the level difference caused by the decorative portion D7 increases. It became. Similarly, it has been clarified that the film-like pressure-sensitive adhesive D9 as described in Patent Document 3 needs to be heated to about 80 ° C. in order to exhibit a sufficient level difference embedding property. Particularly recently, the thickness of the film-like pressure-sensitive adhesive has been reduced, and if a thin film-like pressure-sensitive adhesive is used for the adherend having a high level difference, it becomes more difficult to sufficiently fill the level difference. There is a tendency. In addition, the film-like pressure-sensitive adhesive also needs to have high adhesion to the adherend so that visibility is not lowered due to peeling of the pressure-sensitive adhesive and the adherend.

  In addition, although the pressure-sensitive adhesive sheet described in Patent Document 4 exhibits excellent step embedding in a low temperature process of less than 45 ° C., it has a problem of whitening in a constant temperature and humidity test of 85 ° C., 85% RH and 500 h. It became clear that it would occur.

  The present invention has been made in view of the above circumstances, and provides a pressure-sensitive adhesive layer that is excellent in embedding into a step and excellent in adhesion and visibility even when the step formed on the adherend is high. The pressure-sensitive adhesive sheet for a photocurable image display device provided can be provided by a low-temperature process of less than 45 ° C., and is intended to prevent whitening in a constant temperature and humidity test after the sheets are bonded together. Another object of the present invention is to provide an image display device manufacturing method and an image display device using the pressure-sensitive adhesive sheet for a photocurable image display device.

  As a result of intensive studies by the present inventors, a copolymer of a vinyl compound having an aromatic group and a (meth) acrylate having an alkyl group at the ester position, a compound having an ethylenically unsaturated bond, and a hydrophilic group are contained. It has been found that the above-mentioned problems can be solved by a pressure-sensitive adhesive sheet for a photocurable image display device comprising a pressure-sensitive adhesive layer containing a compound and a photopolymerization initiator. The present invention has been completed based on such findings.

  That is, the present invention provides a copolymer comprising (A) a vinyl compound having an aromatic group and (meth) acrylate having an alkyl group at the ester position ((meth) acrylic acid alkyl ester), (B) A compound having an ethylenically unsaturated bond, (C) a compound containing a hydrophilic group, and (D) a pressure-sensitive adhesive layer containing a photopolymerization initiator, wherein the content of the component (C) is A pressure-sensitive adhesive sheet for a photocurable image display device, which is 5 to 25% by mass based on the total amount, is provided.

  Such a pressure-sensitive adhesive sheet for image display device (hereinafter sometimes simply referred to as “pressure-sensitive adhesive sheet”) is excellent in embedding in a step formed on an adherend even at a low temperature process of less than 45 ° C., Excellent adhesion and visibility, and excellent resistance to whitening after a constant temperature and humidity test.

  The adhesive layer may further contain (E) an oil gelling agent. Thereby, when an oil gelling agent forms an intermolecular force network mutually, a temperature responsiveness and a pressure responsiveness are provided to the elasticity modulus of an adhesion layer, and a level | step difference embedding property can be improved more.

  The vinyl compound having an aromatic group in the component (A) may be at least one compound selected from styrene, benzyl acrylate and benzyl methacrylate. As a result, the crystallinity of the adhesive layer is increased by the π-π stacking interaction of the vinyl compound, the temperature dependency of the elastic modulus of the adhesive layer is increased, and the step embedding property can be further improved. It can be further reduced.

  The (meth) acrylic acid alkyl ester in the component (A) is preferably lauryl acrylate or isostearyl acrylate. As a result, the crystallinity of the adhesive layer is increased by the hydrophobic interaction of the alkyl methacrylate (meth), the temperature dependency of the elastic modulus of the adhesive layer is increased, and the step embedding property can be further improved. The rate can be further reduced.

  The content of the component (A) is preferably 5 to 95% by mass based on the total amount of the adhesive layer. Thereby, the step filling property can be further improved and the dielectric constant can be further reduced.

  The haze of the adhesive layer is preferably 1.5% or less. Thereby, a transparent and clear image can be expressed.

  The said adhesive sheet for photocurable image display apparatuses can further be provided with the 1st base material layer and the 2nd base material layer which were laminated | stacked so that the said adhesive layer might be pinched | interposed. According to such an adhesive sheet, storage and transportation of the adhesive sheet can be facilitated without damaging the adhesive layer.

  The said adhesive sheet for photocurable image display apparatuses may be equipped with the carrier layer further laminated | stacked on the 2nd base material layer. In this case, the outer edges of the first base material layer and the carrier layer may protrude outward from the outer edges of the adhesive layer.

  According to such an adhesive sheet, the outer edges of the first base material layer and the carrier layer that form the outer layer protrude outward from the outer edge of the adhesive layer that forms the inner layer. The outer edge of the layer can be reliably protected. When the adhesive layer is attached to the adherend, the carrier layer can be easily peeled off from the second base material layer by pinching the outer edge portion of the carrier layer protruding outward. 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 also includes a step of bonding the adherends together to obtain a laminated body via an adhesive layer provided in the above-mentioned pressure-sensitive adhesive sheet for a photocurable image display device, and a laminated body of 20 to 45 ° C. and 0.1 Provided is a method for manufacturing an image display device, comprising: a step of heating and pressurizing under a condition of ˜0.6 MPa; and a step of irradiating ultraviolet rays to an adhesive layer in the laminate. The adherend may be at least two selected from the group consisting of a transparent protective plate, a touch panel, and a liquid crystal display cell.

  According to such a method for manufacturing an image display device, by using the pressure-sensitive adhesive sheet according to one embodiment of the present invention, it is possible to manufacture an image display device in which a reduction in visibility is suppressed. By using the pressure-sensitive adhesive sheet according to one embodiment of the present invention, for example, an image display unit such as a liquid crystal display unit mainly composed of a liquid crystal display cell and a touch panel, the image display unit and a transparent protective plate, a touch panel and a transparent protective plate Such members (optical members and the like) required for the image display unit and other image display devices can be bonded together. The manufacturing method according to an embodiment of the present invention is particularly useful when the adherend is a transparent protective plate and a touch panel, or a transparent protective plate and an image display unit. Similarly, by using the pressure-sensitive adhesive sheet according to one embodiment of the present invention, members on the viewing side of the image display unit of the image display device can be bonded together. In that case, for example, even if the transparent protective plate on the viewing side has a high step along the outer periphery, it is presumed that the adhesive layer can surely embed the step, so that the visibility is not lowered. The

  The present invention also includes the image display unit, the transparent protective plate, and the pressure-sensitive adhesive layer or the adhesive layer for the photocurable image display device according to the present invention disposed between the image display unit and the transparent protective plate. An image display device comprising a transparent resin layer that is a cured product thereof is provided.

  The present invention also provides an image display unit, a transparent protective plate, a touch panel disposed between the image display unit and the transparent protective plate, or between the image display unit and the touch panel, or a touch panel and a transparent protective plate. There is provided an image display device comprising: the pressure-sensitive adhesive layer provided in the pressure-sensitive adhesive sheet for a photocurable image display device according to the present invention disposed between the transparent resin layer and a transparent resin layer made of a cured product thereof.

The present invention may further include a step portion that forms a step contacting the transparent resin layer on the image display unit or the transparent protective plate. Furthermore, you may further provide the level | step-difference part which forms the level | step difference which contact | connects a transparent resin layer on the said image display unit, the said touch panel, or the said transparent protective plate.
Provided is an image display device in which 0.4 <(h / t) <1 when the height of the step is h and the thickness of the transparent resin layer is t. At this time, the thickness t of the transparent resin layer is the thickness of the adhesive layer interposed between the adherends not considering the height of the step, and is usually the same as the distance between the adherends.

  According to the present invention, even when the height of the step on the adherend is larger than the thickness of the transparent resin layer, the step can be embedded. That is, when embedding a step having the same height as a conventional one, the pressure-sensitive adhesive layer of the present invention can embed the step on the adherend even when a pressure-sensitive adhesive layer thinner than the conventional pressure-sensitive adhesive layer is used. It tends to be possible.

  The adhesive layer is excellent in step embedding into a high step, and thus has excellent impact resistance and visibility even when a high step is provided on the image display unit, touch panel or transparent protective plate. In addition, an image display device having excellent whitening resistance in a high humidity environment can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, even if the level | step difference formed on a to-be-adhered object is high, it is excellent in level | step difference embedding property, and is equipped with the adhesion layer which is excellent also in adhesiveness and visibility, The adhesive sheet for photocurable image display apparatuses Can be provided in a low temperature process below 45 ° C. ADVANTAGE OF THE INVENTION According to this invention, the adhesive sheet for photocurable image display apparatuses which is excellent in the whitening tolerance in a high humidity environment 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 a perspective view which shows one Embodiment of the adhesive sheet for photocurable image display apparatuses. It is sectional drawing (between II-II of FIG. 1) which shows one Embodiment of the adhesive sheet for photocurable image display apparatuses. It is sectional drawing of a base material film. It is sectional drawing which shows a cutting process. It is sectional drawing which shows a removal process. It is sectional drawing which shows a removal process. It is sectional drawing which shows a sticking process. 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 (1st base material layer). 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 (2nd base material layer). 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 for photocurable image display apparatuses. It is a side view (between XV-XV of FIG. 14) which shows one Embodiment of the adhesive sheet for photocurable image display apparatuses. It is sectional drawing of a base material film. It is sectional drawing which shows a cutting process. It is sectional drawing which shows a removal process. It is sectional drawing which shows a removal process. It is sectional drawing which shows a removal process. It is sectional drawing which shows a sticking process. It is sectional drawing which shows the peeling process of a carrier layer. It is sectional drawing which shows one Embodiment of an image display apparatus. It is a schematic diagram which shows the sample for evaluation of level | step difference embedding property.

  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 in both embodiment shall be demonstrated only in 1st embodiment, and description may be abbreviate | omitted suitably in description of 2nd embodiment. In the present specification, “(meth) acrylate” means “acrylate” and “methacrylate” corresponding thereto. Similarly, “(meth) acryl” means “acryl” and “methacryl” corresponding thereto, and “(meth) acryloyl” means “acryloyl” and corresponding “methacryloyl”.

[First embodiment]
<Adhesive sheet for photocurable image display device>
The pressure-sensitive adhesive sheet for a photocurable image display device according to the present embodiment includes a pressure-sensitive adhesive layer and a pair of 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 FIGS. 1 and 2, the pressure-sensitive adhesive sheet 1 </ b> A according to this embodiment includes a transparent film-like pressure-sensitive adhesive layer 2 and a heavy release separator 3 (second base material layer) sandwiching the pressure-sensitive adhesive layer 2. And a light release separator 4 (first base material layer). The outer edges of the heavy release separator 3 and the light release separator 4 protrude beyond the outer edge of the adhesive layer 2. This adhesive layer 2 is, for example, a transparent film (transparent resin) 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. Layer).

  Since the adhesive sheet 1A according to the present embodiment is used for an image display device, it is usually preferable that the adhesive layer 2 has a haze of 1.5% or less. From the viewpoint of visibility, the haze of the pressure-sensitive adhesive layer 2 may be 1.0% or less, 0.8% or less, or 0.5% or less. The lower limit of the haze of the adhesive layer 2 is preferably close to 0%, but is usually greater than 0% and may be 0.1% or more from a practical viewpoint.

  The haze of the pressure-sensitive adhesive layer 2 depends on the compatibility of the components (A), (B), (C) and (D) described later. If the compatibility between the components (A), (B), (C) and (D) is good, the haze of the pressure-sensitive adhesive layer 2 can be further reduced.

  Haze is a value (%) representing turbidity. From the total transmittance Tt of light irradiated through a lamp and transmitted through a sample, and the transmittance Td of light diffused and scattered in the sample, It is calculated as (Td / Tt) × 100. These are defined by JIS K 7136 (Plastic—How to determine haze of transparent material) and can be easily measured using a commercially available turbidimeter, for example, NDH-5000 manufactured by Nippon Denshoku Industries Co., Ltd.

  Although the thickness of the adhesion layer 2 is not specifically limited since it is suitably adjusted with a use use and a method, 50-200 micrometers, 60-180 micrometers, or 80-150 micrometers may be sufficient. When used in this range, it exhibits particularly excellent effects as a transparent adhesive sheet for laminating an optical member on a display.

  The minimum value of the light transmittance with respect to the light in the visible light region (wavelength: 380 to 780 nm) of the adhesive layer 2 may be 80% or more, 90% or more, or 95% or more. If the light transmittance of the pressure-sensitive adhesive layer 2 is high, the curing can proceed more uniformly.

  The adhesive layer 2 is composed of (A) a copolymer using an aromatic group-containing vinyl compound and (meth) acrylic acid alkyl ester, (B) a compound having an ethylenically unsaturated bond, and (C) hydrophilicity. A compound containing a group, and (D) a photopolymerization initiator. Such a pressure-sensitive adhesive layer 2 is excellent in adhesiveness and visibility, and even when the step formed on the adherend is high, the step can be sufficiently embedded in a low-temperature process of less than 45 ° C. In addition, it has excellent resistance to whitening in a high humidity environment.

  The pressure-sensitive adhesive layer 2 has, for example, (A) a vinyl compound having an aromatic group and a (meth) acrylic acid alkyl ester (an alkyl group at the ester position) on the heavy release separator (second base material layer) 3 ( (Meth) acrylate), (B) a compound having an ethylenically unsaturated bond, (C) a compound containing a hydrophilic group, and (D) an adhesive resin composition containing a photopolymerization initiator It is formed by coating an object with an arbitrary thickness.

  Hereinafter, the adhesive resin composition will be described.

[(A) component: a copolymer comprising a vinyl compound having an aromatic group and a (meth) acrylic acid alkyl ester]
(A) As a copolymer using a vinyl compound having an aromatic group and a (meth) acrylic acid alkyl ester, for example, a copolymer having structural units represented by the following general formulas (I) and (II): Polymers are preferred. The copolymer of component (A) may have a structural unit other than the structural units represented by general formulas (I) and (II).

(A) In component (X), the total number of structural units derived from vinyl compounds having an aromatic group represented by general formula (I) is represented by x, and (meth) acrylic acid represented by general formula (II) The total number of structural units derived from the alkyl ester is indicated by y. In the general formula (I), X represents a monovalent group having an aromatic group, and X is preferably a phenyl group or a benzyl group, and more preferably a phenyl group. In the general formula (II), R ¹¹ represents an alkyl group, and the number of carbon atoms thereof is preferably 4-18, more preferably 5-18, and still more preferably 12-18. In the component (A), x is 10 to 90, preferably 15 to 85, and more preferably 20 to 80. y is 10 to 90, preferably 15 to 85, and more preferably 20 to 80.

In the general formula (II), examples of the alkyl group represented by R ¹¹ include a lauryl group, a tridecyl group, a stearyl group, an isostearyl group, an isodecyl group, an isononyl group, an ethylhexyl group, and a butyl group. Among these, preferred are lauryl group and isostearyl group, and isostearyl group is particularly preferred.

  The copolymer having the structural units represented by the general formulas (I) and (II) is obtained by copolymerizing a vinyl compound having an aromatic group and a (meth) acrylic acid alkyl ester by a known method. I can do it.

  Examples of the vinyl compound having an aromatic group include styrene, 4-vinyltoluene, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, naphthalenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, and the like. . Among these vinyl compounds, styrene (manufactured by Wako Pure Chemical Industries), benzyl acrylate FA-BzA (manufactured by Hitachi Chemical Co., Ltd., trade name), benzyl methacrylate FA-BzM (Hitachi Chemical) Product name). By having an aromatic group, the crystallinity is increased due to the π-π interaction, and a sufficient storage elastic modulus as a sheet can be ensured.

  The number of carbon atoms of the alkyl group in the (meth) acrylic acid alkyl ester is preferably 4-18, more preferably 5-18, and still more preferably 12-18. By setting the number of carbon atoms to 12 or more, the crystallinity increases due to the hydrophobic interaction, and a sufficient storage elastic modulus as a sheet can be ensured. Furthermore, the higher the crystallinity, the greater the temperature dependency of the storage elastic modulus, and the range of change of the storage elastic modulus due to heating increases, thereby exhibiting excellent step embedding properties. Furthermore, since the storage elastic modulus is increased by weak bonds compared to chemical bonds such as π-π interaction and hydrophobic interaction, the storage elastic modulus is highly pressure-dependent, and the pressure at room temperature without heating is high. By controlling the above, excellent level difference embedding is expressed.

  As (meth) acrylic acid alkyl ester, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, isodecyl (meth) acrylate, isononyl (meth) acrylate, ethylhexyl (meth) Examples include acrylate and butyl acrylate. Among these, lauryl (meth) acrylate or isostearyl (meth) acrylate is preferable, and isostearyl (meth) acrylate is particularly preferable.

  The content of the component (A) is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 50% by mass or more, based on the total amount of the adhesive layer (adhesive resin composition). Furthermore, the content of the component (A) is preferably 95% by mass or less, more preferably 90% by mass or less, and still more preferably 85% by mass or less, based on the total amount of the adhesive resin composition. When the content of the component (A) is in such a range, the peel strength when the adhesive resin composition is a cured product can be further improved, and the dielectric constant can be further reduced.

[Component (B): Compound having an ethylenically unsaturated bond]
The compound having an ethylenically unsaturated bond as component (B) is preferably a compound having one or more (meth) acryloyl groups, and more preferably a compound having two or more (meth) acryloyl groups. . The component (B) is selected in consideration of compatibility with the component (A), the component (C), and the component (D) so that the haze of the adhesive layer 2 is reduced.

  Specific examples of the component (B) include alkylene diol di (meth) acrylate having 6 to 18 carbon atoms, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyester (meth) acrylate, urethane ( (Meth) acrylate, epoxy acrylate (resin obtained by reacting epoxy resin and (meth) acrylic acid), trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate , Dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, polyester oligomer having (meth) acryloyl group, urea having (meth) acryloyl group Down polymers include butadiene polymers, etc. having a (meth) acryloyl groups.

  The content of the component (B) is preferably 5% by mass or more, more preferably 10% by mass or more, based on the total amount of the adhesive resin composition (adhesion layer). When the content of the component (B) is 5% by mass or more, the resin composition can have an appropriate viscosity, workability at the time of application can be improved, and the curing shrinkage rate can be further increased. There is a tendency to be able to lower. Furthermore, the content of the component (B) is preferably 40% by mass or less, more preferably 30% by mass or less, and still more preferably 20% by mass or less, based on the total amount of the adhesive resin composition. When the content of the component (B) is 40% by mass or less, the curing shrinkage rate and the elastic modulus of the adhesive resin composition can be further suppressed from being too high. When used in an image display device, There is a tendency that the occurrence of display unevenness can be further suppressed.

[Component (C): Compound containing a hydrophilic group]
Hydrophilicity refers to the physical properties of chemical species and substituents that have an affinity for water, and the affinity is usually derived from hydrogen bonding. By forming a hydrogen bond with water, it is a property that is easily dissolved in water or easily mixed with water, and is a thermodynamically preferable phenomenon (reducing free energy). The hydrophilic group includes a hydroxyl group (—OH), an amino group (a monovalent functional group (—NH ₂ , —NHR, —NRR ′) obtained by removing hydrogen from ammonia, a primary amine, or a secondary amine in the molecule. ), A group represented by RCONH— in which an amino group (—NH ₂ ) and an acyl group RCO— are bonded, or an acid amide group (RCO—NH ₂ ) in which one hydrogen atom of ammonia NH ₃ is substituted with an acyl group RCO— ).
The compound (C) containing a hydrophilic group is preferably a (meth) acrylate having one or more hydroxy groups and amide groups.

  Specific examples of the component (C) include hydroxyl group-containing monomers such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, and glycerol methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate. Alkyl-substituted amino group-containing monomers such as N, N-dimethylacrylamide, N, N-diethylacrylamide, N-methylacrylamide, methylenebisacrylamide, diacetone acrylamide, N-vinylpyrrolidone, N-vinyl-N-methylacetamide, etc. And amide group-containing monomers.

  (C) Content of a component is 5 mass% or more on the basis of the total amount of an adhesion layer (adhesive resin composition). (C) If content of a component is 5 mass% or more, moderate hydrophilicity can be provided to an adhesive resin composition, and the water | moisture content produced when it takes out from a high-temperature, high-humidity environment in a composition is included. It can be dispersed to suppress the whitening phenomenon. Furthermore, content of (C) component is 25 mass% or less on the basis of the total amount of an adhesion layer (adhesive resin composition), Preferably it is 15 mass% or less, More preferably, it is 10 mass% or less. If content of (C) component is 25 mass% or less, while it can ensure whitening tolerance, it will suppress that a storage elastic modulus becomes low too much, and there exists a tendency which can ensure sufficient adhesive force.

[(D) component: photopolymerization initiator]
(D) The photoinitiator of a component is a component which 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 (D) is not particularly limited, and materials such as benzophenone, anthraquinone, benzoyl, sulfonium salt, diazonium salt, and onium salt can be used.

  Specific examples of the photopolymerization initiator include benzophenone, N, N, N ′, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), N, N, N ′, N′-tetraethyl-4, 4′-diaminobenzophenone, 4-methoxy-4′-dimethylaminobenzophenone, α-hydroxyisobutylphenone, 2-ethylanthraquinone, t-butylanthraquinone, 1,4-dimethylanthraquinone, 1-chloroanthraquinone, 2,3-dichloro Anthraquinone, 3-chloro-2-methylanthraquinone, 1,2-benzoanthraquinone, 2-phenylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, thioxanthone, 2-chlorothioxanthone, 1-hydroxycyclohexylphenyl Ketone, 2,2-dimethyl Aromatic ketone compounds such as toxi-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-diethoxyacetophenone; benzoin, methylbenzoin, ethyl Benzoin compounds such as benzoin; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether and benzoin phenyl ether; benzyl compounds such as benzyl and benzyldimethyl ketal; β- (acridin-9-yl) (meth) acryl Ester compounds such as acids; acridine compounds such as 9-phenylacridine, 9-pyridylacridine, 1,7-diacridinoheptane; 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- ( o-Chloro Enyl) -4,5-di (m-methoxyphenyl) 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, 2,4,5-triarylimidazole dimers such as 4-dimethoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methylmercaptophenyl) -4,5-diphenylimidazole dimer; 2-Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone; 2-methyl-1- [4- (methylthio) phenyl] -2-mol Holino-1-propane; bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide; oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone) and the like Can be mentioned. These compounds may be used in combination.

  In particular, as the component (D), a photopolymerization initiator that does not substantially color the adhesive layer (adhesive resin composition) can be used. Specific examples thereof include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2- Α-hydroxyalkylphenone compounds such as methyl-propan-1-one; bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4- Acylphosphine oxide compounds such as trimethyl-pentylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl)) Phenyl) propanone). A combination of these may also be used.

  When producing a particularly thick sheet (adhesive layer), the component (D) is bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4. An acyl phosphine oxide compound such as trimethyl-pentylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide may be included.

  (D) Content of component is 0.05-5 mass%, 0.1-3 mass%, or 0.1-2 mass% on the basis of the total amount of adhesive resin composition (adhesion layer), Also good. By setting the content of the component (D) to 5% by mass or less, it is possible to obtain an adhesive layer having higher light transmittance, a hue that is not yellowish, and excellent in step embedding. . When the content of the component (D) is 0.05% by mass or more, photopolymerization tends to be started more favorably. Further, when the component (D) is within these ranges, the effect of excellent adhesion and reliability under high temperature and high humidity can be obtained more remarkably.

<(E) component: oil gelling agent>
The pressure-sensitive adhesive sheet for a photocurable image display device of the present invention may contain an oil gelling agent as the component (E).

  As the component (E), hydroxy fatty acid, fatty acid amide, n-lauroyl-L-glutamic acid-α, β-dibutyramide, di-p-methylbenzylidene sorbitol glucitol, 1,3: 2,4-bis-0 -Benzylidene-D-glucitol, 1,3: 2,4-bis-0- (4-methylbenzylidene) -D-sorbitol, bis (2-ethylhexanoato) hydroxyaluminum, and the following general formulas (1) to ( And the compound represented by 12).

In the general formula (1), the total number of structural units represented by (—CF ₂ —) (hereinafter also referred to as “structural unit (1-1)”) is represented by p, and represented by (—CH ₂ —). The total number of structural units (hereinafter, also referred to as “structural unit (1-2)”) is denoted by q. In general formula (1), the polymerization form of p structural units (1-1) and q structural units (1-2) may be either block copolymerization or random copolymerization. p is an integer of 3 to 10, q is an integer of 2 to 6, R ¹ is a saturated hydrocarbon group having 1 to 20 carbon atoms, and X is sulfur or oxygen.
In the general formula (2), R ² is a saturated hydrocarbon group having 1 to 20 carbon atoms, and Y ¹ is a bond (single bond) or a benzene ring.
In the general formula (3), ^{R 3} is a saturated hydrocarbon group having 1 to 20 carbon atoms, ^{Y 2} is a bond or a benzene ring.
In the general formula ^{(4), R} 4 is a saturated hydrocarbon group having 1 to 20 carbon atoms.
In General Formula (6), R ⁵ and R ⁶ are each independently a saturated hydrocarbon group having 1 to 20 carbon atoms.
In the general formula (7), ^{R 7} is a saturated hydrocarbon group having 1 to 20 carbon atoms.
In the general formula (8), ^{R 8} is a saturated hydrocarbon group having 1 to 20 carbon atoms.
In general formula (9), Ph is a phenyl group.
In General Formula (10), R ⁹ and R ¹⁰ are each independently a saturated hydrocarbon group having 1 to 20 carbon atoms.
These compounds may have a substituent and can be used alone or in combination of two or more.

  These oil gelling agents express non-covalent intermolecular interactions such as hydrogen bonds, electrostatic interactions, π-π interactions, van der Waals forces, etc., and are linked to each other to form fibrous bonds. . As a result, at least a part of the photocurable adhesive resin composition becomes a physical gel-like substance (hereinafter sometimes referred to as gelation or gel-like) in a temperature range of less than about 50 ° C. By gelling, the step embedding property at the time of bonding the panels can be improved, and the bleeding of the end portion at the time of bonding can be suppressed. As the oil gelling agent, hydroxy fatty acid is preferable from the viewpoint of transparency, workability, and compatibility.

  The content of the oil gelling agent (E) component is preferably 0.1 to 20% by mass with respect to the total amount (total amount) of the pressure-sensitive adhesive layer (photocurable pressure-sensitive adhesive resin composition). When it is 0.1% by mass or more, it can be sufficiently gelled, and when it is 20% by mass or less, the content of the component (B) is relatively increased and can be sufficiently photocured. In this respect, the content is more preferably 0.2 to 15% by mass, and further preferably 0.3 to 10% by mass.

<Other ingredients>
In addition to the above components (A), (B), (C), (D), and (E), the adhesive layer (photo-curable adhesive resin composition) may contain acrylic monomers and various types as necessary. You may contain an additive etc. As various additives, for example, a polymerization inhibitor such as p-methoxyphenol added for the purpose of enhancing the storage stability of the adhesive resin composition, the heat resistance of the adhesive layer obtained by photocuring the adhesive resin composition Antioxidants such as triphenyl phosphite added for the purpose of improving the light resistance, light stabilizers 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, glass, etc. Examples thereof include a silane coupling agent to be added in order to increase the adhesion of the adhesive resin composition to the adhesive.

  A well-known technique can be used as a method of processing the photocurable adhesive resin composition into a sheet or film. For example, the above-mentioned photocurable adhesive resin composition is diluted with a ketone solvent such as methyl ethyl ketone or cyclohexanone to prepare a coating liquid, and then the coating liquid is flow-coated on a substrate such as a polymer film. Coating is performed by a method, a roll coating method, a gravure roll method, a wire bar method, a lip die coating method or the like. Next, by removing the solvent, it can be processed into a sheet or film having an arbitrary film thickness.

  The pressure-sensitive adhesive layer 2 includes a base material layer (heavy release separator (second base material layer 3) 3) that is a polymer film such as a polyethylene terephthalate film (hereinafter also referred to as “PET film”), and the same kind as this. It may be sandwiched between base material layers (light release separator (first base material layer) 4) which is a cover film of the material. At this time, in order to control the peelability between the pressure-sensitive adhesive layer 2 and the base material layer, the photocurable pressure-sensitive adhesive resin composition may contain a polydimethylsiloxane-based, fluorine-based surfactant or the like. .

  These additives can be used alone or in combination of two or more. The content of these additives is usually small compared to the total content of the above components (A), (B), (C) and (D), and is generally a photocurable adhesive resin composition. Based on the total amount of 0.01 to 5% by mass.

  The heavy release separator (second base material layer) 3 may be a polymer film such as polyethylene terephthalate, polypropylene, polyethylene, or polyester. The heavy release separator 3 can be a PET film. The thickness of the heavy release separator 3 may be 50 to 200 μm, 60 to 150 μm, or 70 to 130 μm from the viewpoint of workability.

  The main surface of the heavy release separator 3 may be larger than the main surface of the adhesive layer 2, and the outer edge of the heavy release separator 3 may protrude outward from the outer edge of the adhesive layer 2. The width of the heavy release separator 3 in a portion protruding from the outer edge of the adhesive layer 2 may be 2 to 20 mm or 4 to 10 mm from the viewpoint of ease of handling, ease of peeling, and adhesion of dust and the like. Good. When the main surfaces of the pressure-sensitive adhesive layer 2 and the heavy release separator 3 are substantially rectangular, such as a substantially rectangular shape, the width of the heavy release separator 3 in a portion protruding from the outer edge of the pressure-sensitive adhesive layer 2 is 2 to 20 mm at least on one side. Alternatively, it may be 4 to 10 mm, or 2 to 20 mm or 4 to 10 mm on all sides.

  Examples of the light release separator 4 (first base material layer) include polymer films such as polyethylene terephthalate, polypropylene, polyethylene, and polyester. The light release separator 4 can be a PET film. The thickness of the light release separator 4 may be 25 to 150 μm, 30 to 100 μm, or 40 to 75 μm from the viewpoint of workability. The main surface of the light release separator 4 is preferably larger than the main surface of the pressure-sensitive adhesive layer 2, and the outer edge of the light release separator 4 is more preferably projected outward from the outer edge of the pressure-sensitive adhesive layer 2. The width of the light release separator 4 in the portion protruding from the outer edge of the adhesive layer 2 may be 2 to 20 mm or 4 to 10 mm from the viewpoint of ease of handling, ease of peeling, and adhesion of dust and the like. it can. When the planar shape of the pressure-sensitive adhesive layer 2 and the light release separator 4 is a substantially rectangular shape such as a substantially rectangular shape, the width of the light release separator 4 that protrudes from the outer edge of the pressure-sensitive adhesive layer 2 is at least on one side. It may be 2-20 mm or 4-10 mm, or 2-20 mm or 4-10 mm on all sides.

  The peel strength between the light release separator 4 and the adhesive layer 2 may be 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. As will be described later, when the blade B is passed through the pressure-sensitive adhesive layer 2 toward the heavy release separator 3, the outer edge portion of the pressure-sensitive 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 it becomes easier to release the light release separator 4 before the heavy release separator 3 is peeled off. Therefore, the heavy release separator 3 and the light release separator 4 can be peeled one by one, and the work of peeling the heavy release separator 3 and the light release separator 4 and sticking the adhesive layer 2 to separate adherends is ensured one by one. Can be done. 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 release treatment with a silicone compound or a fluorine compound.

<Method I for manufacturing a pressure-sensitive adhesive sheet for a photocurable image display device I (three-layer product)>
The pressure-sensitive adhesive sheet 1A described above can be manufactured, for example, by the following method. First, as shown in FIG. 3, a base material film 10A having a heavy release separator 3, an adhesive layer 2 provided on the heavy release separator 3, and a temporary separator 6 provided on the adhesive layer 2 is prepared. To do. 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. 4, the temporary separator 6 and the adhesive layer 2 are cut into a desired shape by the blade B provided in the punching device (not shown). 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, it is preferable to use a rotary punching device. Moreover, a laser cutter can also be used for the said cutting | disconnection. In this step, the blade B can be passed through the temporary separator 6 and the adhesive layer 2 to a depth that reaches the heavy release separator 3, and the temporary separator 6 and the adhesive layer 2 can be cut. 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. 5, the temporary separator 6 is peeled off from the adhesive layer 2 as shown in FIG. 6, and the adhesive as shown in FIG. The light release separator 4 is laminated on the layer 2. The adhesive sheet 1A for a photocurable image display device is completed through the above steps.

<Image display device>
Next, an image display device manufactured using the pressure-sensitive adhesive sheet for photocurable image display device 1A (three-layer product) or the photocurable image display device pressure-sensitive adhesive sheet 1B (four-layer product) described below will be described. The pressure-sensitive adhesive layer 2 provided in the pressure-sensitive adhesive sheet 1A or 1B 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 adhesive layer 2 of the present embodiment is 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. You can also.

  The antireflection layer may be a layer having antireflection properties such that the visible light reflectance is 5% or less. A layer obtained by treating a transparent substrate such as a transparent plastic film by a known antireflection method can be used as the antireflection layer.

  The antifouling layer is for preventing the surface from becoming dirty, and a known layer made of a fluorine-based resin or a silicone-based resin can be used as the antifouling layer in order to lower the surface tension.

  The dye layer is used to increase color purity, and is used to reduce light components having unnecessary wavelengths when the color purity of light emitted from an image display unit such as a liquid crystal display unit is low. The dye layer can be obtained by dissolving a dye that absorbs an optical component having an unnecessary wavelength in a resin and forming or laminating it on a base film such as a polyethylene film or 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 an epoxy resin; a polyethylene film, can be used, for example. Similarly, in order to increase the surface hardness, it is possible to use a transparent protective plate made of glass, acrylic resin, polycarbonate resin or the like and a hard coat layer formed or laminated thereon.

  The adhesive layer 2 can be used by being laminated on a polarizing plate. At this time, the adhesive layer 2 can be laminated on the viewing surface side of the polarizing plate, or can be laminated on the opposite side.

  An antireflection layer, an antifouling layer, a hard coat layer or the like can be further laminated on the viewing surface side of the adhesive layer 2 laminated on the viewing surface side of the polarizing plate. When the adhesive layer 2 is provided between the polarizing plate and the liquid crystal cell, a functional layer can be laminated on the viewing surface side of the polarizing plate.

  Such a laminate can be obtained by laminating the pressure-sensitive adhesive layer 2 using a roll laminate, a vacuum bonding machine, a single wafer bonding machine, or the like.

  The adhesive layer 2 may be disposed at an appropriate position between the image display unit of the image display device and the transparent protective plate provided closer to the viewer than the image display unit. Specifically, the adhesive layer 2 may be applied as a transparent resin layer provided between the image display unit and the transparent protective plate.

  In an image display device including a combination of a touch panel and an image display unit, the adhesive layer 2 may be applied as a transparent resin layer provided between the touch panel and the image display unit or between the touch panel and the transparent protective plate. However, the position where the pressure-sensitive adhesive layer 2 is provided is not limited as long as the pressure-sensitive adhesive layer 2 of the present embodiment is applicable to the configuration of the image display device.

  Hereinafter, a liquid crystal display device which is one of image display devices will be described in detail with reference to FIGS. 8 and 9 as an example.

  FIG. 8 is a side sectional view schematically showing an embodiment of a liquid crystal display device. The liquid crystal display device shown in FIG. 8 has a backlight system 50, a polarizing plate 22, a liquid crystal display cell 12, and a polarizing plate 20, and these are laminated in this order toward the viewing side of the liquid crystal display device. The unit 7 includes a transparent resin layer 32 provided on the viewing side surface of the polarizing plate 20, and a transparent protective plate (protective panel) 40 facing the image display unit 7 with the transparent resin layer 32 interposed therebetween. Is done. On the peripheral edge of the surface of the transparent protective plate 40 on the transparent resin layer 32 side, a step is formed by the step portion 60 and the transparent protective plate 40, and this step is embedded by a part of the transparent resin layer 32. ing.

  The transparent resin layer 32 corresponds to the adhesive layer 2 according to the above-described embodiment or a cured product thereof. Although the level difference due to the level difference portion 60 varies depending on the size of the liquid crystal display device or the like, when the height is 40 to 100 μm, particularly 60 to 100 μm, it is particularly useful to use the adhesive layer of this embodiment. When the height of the stepped portion 60 is in the above range, the adhesive layer 2 is preferably thicker from the viewpoint of the step embedding property, but the adhesive layer 2 of the present embodiment has a step embedding property even when the film thickness is small. Excellent. When the height of the step portion is h and the thickness of the transparent resin layer is t, excellent step embedding property is obtained even if 0.4 <(h / t) <1. Moreover, the pressure-sensitive adhesive layer 2 of the present embodiment exhibits excellent step embedding properties even when (h / t)> 0.5. From a practical viewpoint, (h / t) <0.9 may be satisfied.

  FIG. 9 is a side cross-sectional view schematically showing a liquid crystal display device equipped with a touch panel, which is an embodiment of the image display device. The liquid crystal display device shown in FIG. 9 has a backlight system 50, a polarizing plate 22, a liquid crystal display cell 12, and a polarizing plate 20, and these are laminated in this order toward the viewing side of the liquid crystal display device. The unit 7 includes a transparent resin layer 32 provided on the viewing side surface of the polarizing plate 20 and a transparent protective plate 40 facing the touch panel 30 with the transparent resin layer 32 interposed therebetween. A step is formed by the step portion 60 and the transparent protective plate 40, and the step is embedded by a part of the transparent resin layer 31. The transparent resin layer 31 and the transparent resin layer 32 may correspond to the adhesive layer according to the above-described embodiment or a cured product thereof.

  In the liquid crystal display device of FIG. 9, a 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. However, the transparent resin layer only needs to be interposed in at least one of these, and particularly when the adhesive layer 2 of the present embodiment is used as the transparent resin layer, the touch panel 30 and the transparent protective plate 40 forming a step are provided. It is preferable that a transparent resin layer is interposed therebetween. When the touch panel is on-cell, the touch panel and the liquid crystal display cell are integrated. As a specific example thereof, a liquid crystal display device in which the liquid crystal display cell 12 of the liquid crystal display device of FIG.

  In recent years, development of a liquid crystal display cell called an in-cell type touch panel incorporating a touch panel function has been advanced. A liquid crystal display device provided with such a liquid crystal display cell includes, for example, a transparent protective plate, a polarizing plate, and a liquid crystal display cell (a liquid crystal display cell with a touch panel function). The pressure-sensitive adhesive layer 2 of the pressure-sensitive adhesive sheet according to this embodiment can also be used for a liquid crystal display device that employs such an in-cell touch panel.

  Since the liquid crystal display device shown in FIGS. 8 and 9 includes the adhesive layer of this embodiment as the transparent resin layer 31 or 32, the liquid crystal display device has impact resistance, and can obtain a clear and high contrast image without double reflection. Is possible.

  As the liquid crystal display cell 12, a liquid crystal material that is well known in the art can be used. The liquid crystal display cell is classified into a TN (Twisted Nematic) method, a STN (Super-Twisted Nematic) method, a VA (Vertical Alignment) method, an IPS (In-Place-Switching) method, etc., depending on the control method of the liquid crystal material. The liquid crystal display device according to the present embodiment 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. Treatments such as antireflection, antifouling, and hard coating may be performed on one or both surfaces of the polarizing plates.

  As the touch panel 30, a resistive film method in which an electrode comes in contact with the pressure of a finger or object touching the surface, a capacitance method that senses a change in capacitance when the finger or object touches the surface, an electromagnetic induction method, or the like However, the adhesive layer 2 of the present invention is particularly suitable for use in a liquid crystal display device employing a capacitive touch panel. As the touch panel 30, a touch panel generally used in this technical field can be used. For example, the capacitive touch panel has a structure in which a transparent electrode is formed on a substrate. Can be mentioned. Examples of the substrate include a glass substrate, a PET film, and a cycloolefin polymer film. Moreover, as a transparent electrode, the metal oxide of ITO (Indium Tin Oxide) is mentioned, for example. The thickness of the substrate is 20 to 1000 μm. The transparent electrode has a thickness of 10 to 500 nm.

  In addition, when using the adhesion layer 2 which concerns on this embodiment for an electrostatic capacitance type touch panel, it is preferable that the dielectric constant of the adhesion layer 2 is an appropriate range. The dielectric constant at 100 kHz at room temperature (25 ° C.) of the adhesive layer 2 is, for example, 2.0 to 4.5, 2.0 to 4.0 or 3.5 when the adhesive layer 2 is used between the touch panel and the transparent protective plate. It may be -4.0. If the dielectric constant is 2.0 or more, the response of the touch panel tends to be sufficiently secured, and if it is 4.0 or less, the malfunction due to the too high response tends to be sufficiently reduced.

  The thickness of the transparent resin layer 31 or 32 may be, for example, 0.02 to 3 mm or 50 to 200 μm. In particular, when the pressure-sensitive adhesive layer 2 of the present embodiment is used for the transparent resin layer 31 or 32, a sufficient step embedding property is exhibited even if the transparent resin layer is thin, but a more excellent effect is exhibited when the transparent resin layer is thick. Can be made.

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

  The backlight system 50 typically includes a reflecting unit such as a reflecting plate and an illuminating unit such as a lamp.

<Manufacturing method I of image display device (using three-layer product)>
The pressure-sensitive adhesive sheet 1A is used as follows in assembling an image display device. First, as shown in FIG. 10, the light release separator 4 is peeled from the pressure-sensitive adhesive sheet 1 </ b> A to expose the pressure-sensitive adhesive surface 2 b of the pressure-sensitive adhesive layer 2. Subsequently, as shown in FIG. 11, the adhesive surface 2b of the adhesive layer 2 is attached to the adherend A1, and the adhesive layer 2 is pressed against the adherend A1 with a roller R or the like. At this time, the step formed by the stepped portion 60 on the surface of the adherend A1 is buried by the flow of the adhesive layer 2. When the pressure-sensitive adhesive layer 2 is pressed against the adherend A1, the pressure-sensitive adhesive layer 2 may be heated to 20 to 45 ° C., for example. By heating the pressure-sensitive adhesive layer 2 to 20 to 45 ° C., the pressure-sensitive adhesive layer 2 becomes easier to flow, and an effect that the step embedding property in the stepped portion 60 is excellent is obtained. The adherend A1 is, for example, an image display unit, a transparent protective plate, or a touch panel.

  Subsequently, as shown in FIG. 12, the heavy release separator 3 is peeled from the adhesive layer 2 to expose the adhesive surface 2 c of the adhesive layer 2. Subsequently, as shown in FIG. 13, the pressure-sensitive adhesive surface 2 c of the pressure-sensitive adhesive layer 2 is attached to the adherend A <b> 2, and the obtained laminate is heated and pressurized (for example, treatment by autoclave). 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. Conditions for heating and pressurizing the laminate are, for example, a temperature of 20 to 45 ° C. and a pressure of 0.1 to 0.6 MPa. The time of heating and pressurization may be 3 to 60 minutes, or 10 to 50 minutes.

  The said manufacturing method includes the process of irradiating an ultraviolet-ray from either one side of both adherends (for example, a transparent protective board, a touch panel) with respect to the adhesion layer 2 before or after the heating and pressurization of a laminated body. But you can. Thereby, the reliability (reduction of bubbles and suppression of peeling) and adhesive strength under high temperature and high humidity can be further improved. From the viewpoint of further improving the reliability under high temperature and high humidity, the adhesive layer 2 can be irradiated with ultraviolet rays from the side of the adherend (eg, touch panel) that does not have a stepped portion.

  Here, when irradiating active energy rays, such as an ultraviolet-ray, to the adhesive resin composition with respect to the adhesion layer 2 from any one side of both adherends (for example, a transparent protective board, a touch panel), the level | step-difference part 60 is provided. If it is light-shielding, as shown in FIG. 13, it is difficult for active energy rays to reach the area (light-shielding part) located between the step part 60 and the adherend A2 (for example, a transparent protective plate or a touch panel). , Curing tends to be difficult to proceed.

  In the case where the step portion 60 is light-shielding, in the manufacturing method described above, in addition to the above-described ultraviolet irradiation, the step portion 60 and the adherend A2 (for example, a transparent protective plate, It is preferable to irradiate ultraviolet rays toward the adhesive resin composition of the adhesive layer 2 in a region located between the touch panel). The irradiation angle of ultraviolet rays is not particularly limited, and can be 0 ° or more and less than 90 ° with respect to the horizontal direction.

The dose of ultraviolet rays is not particularly limited, it may be ^{5.0 × 10 2 mJ / cm 2} ~5.0 × 10 3 mJ / cm 2. The step of irradiating with ultraviolet rays can be performed after heating and pressurization of the laminate from the viewpoint of improving reliability under high temperature and high humidity.

  In the structure obtained through heating and pressurization and, if necessary, ultraviolet irradiation to the adhesive layer, for example, when the adherend is a glass substrate (soda lime glass) or an acrylic resin substrate, the adhesive layer 2 and these substrates 5 to 30 N / 10 mm, 7 to 30 N / 10 mm, or 10 to 30 N / 10 mm may be sufficient. The peel strength can be measured as 180 degree peel (3 seconds at a peeling speed of 300 mm / min, measurement temperature 25 ° C.) using a tensile tester (“Tensilon RTC-1210” manufactured by Orientec Co., Ltd.).

  Through the above steps, the adhesive layer 2 or a cured product thereof is disposed as a transparent resin layer between the adherend A1 and the adherend A2. In particular, the adhesive layer 2 (transparent resin layer) can be disposed between the transparent protective plate and the touch panel, or between the touch panel and the image display unit.

  The liquid crystal display device of FIG. 8 can be manufactured by obtaining a laminate by interposing the adhesive layer 2 between the image display unit 7 and the transparent protective plate 40. That is, in the image display device shown in FIG. 8, the adhesive layer 2 of this embodiment can be laminated on the upper surface of the polarizing plate 20 by a laminating method.

  The liquid crystal display device of FIG. 9 is manufactured by obtaining the laminate by interposing the adhesive layer 2 of the present embodiment between the image display unit 7 and the touch panel 30 or between the touch panel 30 and the transparent protective plate 40. can do.

[Second Embodiment]
<Photosensitive image display device pressure-sensitive adhesive sheet II (four-layer product)>
The pressure-sensitive adhesive sheet 1B (four-layer product) of the present embodiment includes a film-like pressure-sensitive adhesive layer, first and second base material layers laminated so as to sandwich the pressure-sensitive adhesive layer, and a second layer. A carrier layer further laminated on the base material 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. 14 and FIG. 15, the pressure-sensitive adhesive sheet 1 </ b> B according to the present embodiment includes a transparent film-like pressure-sensitive adhesive layer 2 and a light release separator 4 (first film) 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 heavy release separator 3 by pinching the outer edge portion of the carrier film 5 protruding outward. 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 width of the portion of the carrier film 5 that protrudes from the outer edge 4a of the light release separator 4 is 0.5 to 10 mm or 1 to 5 mm from the viewpoint of ease of handling, ease of peeling, and adhesion of dust and the like. There may be. 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 substantially rectangular shape such as a substantially rectangular shape, the portion of the carrier film 5 that protrudes from the outer edge 4 a of the light release separator 4. The width may be 0.5-10 mm or 1-5 mm on at least one side, or 0.5-10 mm or 1-5 mm on all sides.

  Since the heavy release separator 3 is protected by the carrier film 5 until immediately before the process, 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.

  Examples of the carrier film (carrier layer) 5 include polymer films such as polyethylene terephthalate, polypropylene, polyethylene, and polyester. The polymer film may be a PET film. From the viewpoint of workability, the thickness of the carrier film 5 may be 15 to 100 μm, 20 to 80 μm, or 20 to 50 μm.

  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 preferably lower than the peel strength between the light release separator 4 and the pressure-sensitive adhesive layer 2, but may be high.

  The peel strength between the carrier film 5 and the heavy release separator 3 may be adjusted, for example, by providing an adhesive layer (or adhesive) between the carrier film 5 and the heavy release separator 3. The peel strength can be adjusted depending on the type of adhesive layer to be formed and the thickness of the adhesive layer. Examples of the type of adhesive formed between the carrier film 5 and the heavy release separator 3 include acrylic adhesives. The thickness of the adhesive layer formed between the carrier film 5 and the heavy release separator 3 may be 0.1 to 10 μm or 1 to 5 μm.

  As described above, according to the pressure-sensitive adhesive sheet 1B of the present embodiment, the heavy release separator 3, the light release separator 4 and the carrier film 5 can be reliably and in a predetermined order without protecting the adhesive layer 2 and easily. Can be peeled off.

<Method for producing pressure-sensitive adhesive sheet for photocurable image display device>
The pressure-sensitive adhesive sheet 1B for a photocurable image display device of the present embodiment is manufactured, for example, as follows. First, as shown in FIG. 16, a base material film 10 </ b> 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 heavy release separator 3 is adhered to the carrier film 5 via the adhesive layer as necessary. 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 a desired shape by a punching device (not shown) provided with the blade B. In this step, as shown in FIG. 17, the blade B can be passed 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, as shown in FIG. 18, the outer portions of the temporary separator 6, the adhesive layer 2 and the heavy release separator 3 are removed. At this time, the outer edge of the heavy release separator 3 is substantially flush with the outer edge of the carrier film 5 as shown in FIG. 19 so that the outer edge of the carrier film 5 does not protrude outward from the outer edge of the heavy release separator 3. It may be. That is, only the outer portions of the temporary separator 6 and the pressure-sensitive adhesive layer 2 are removed, and the outer portion of the heavy release separator 3 is left on the carrier film 5 without being removed. It may be in the state. Thereby, it can prevent effectively that the carrier film 5 by which surface exposure was carried out adheres to another part.

  After removing the outer portions of the temporary separator 6, the adhesive layer 2 and the heavy release separator 3 as shown in FIG. 18, 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 it is a film cut so that the outer edge of the heavy release separator 3 is substantially flush with the outer edge of the adhesive layer 2, the difference in ease of peeling between the light release separator 4 and the heavy release separator 3. Therefore, the light release separator 4 can be more easily peeled before the heavy release separator 3 is peeled off. 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 of the adhesive layer 2 are aligned, the alignment between the adhesive layer 2 and the adherend becomes easy.

<Method for Manufacturing Image Display Device>
The pressure-sensitive adhesive sheet 1B of the present embodiment is the same as the pressure-sensitive adhesive sheet 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.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not necessarily limited to the said embodiment, A various change is possible in the range which does not deviate from the summary.

  Hereinafter, the present invention will be described more specifically with reference to examples. In this example, the pressure-sensitive adhesive sheet for a photocurable image display device according to the first embodiment and the second embodiment is produced, but the present invention is not limited to these examples.

<(A) Component: Synthesis of Copolymer Using Vinyl-Based Compound Having Aromatic Group and (Meth) Acrylic Acid Alkyl Ester>
(Production Example 1)
In a 2 L reaction vessel, 700 g of methyl isobutyl ketone was charged as the component (I) shown in Table 1, and heated to the first stage synthesis temperature (125 ° C.) under a nitrogen gas atmosphere and a gauge pressure of 0.30 MPa. 210 g of styrene (manufactured by Nippon Oxirane Co., Ltd.), a vinyl compound having an aromatic group as component (II) at 125 ° C., isostearyl acrylate (produced by Osaka Organic Chemical Co., Ltd., trade name) as alkyl (meth) acrylate "ISTA") 490 g, polymerization initiator perbutyl O (t-butylperoxy-2-ethylhexanoate, NOF Corporation, trade name) 49 g, and methyl isobutyl ketone (Mitsubishi Chemical Corporation, trade name) “MIBK”) (70 g) was dropped into the reaction vessel over 2 hours. After completion of the dropwise addition, the reaction was further carried out at the same temperature for 1 hour, and thereafter, a mixed liquid of 7 g of perbutyl O and 140 g of methyl isobutyl ketone was dropped into the reaction vessel over 1 hour as the component (IV). After completion of the dropwise addition, 105 g of methyl isobutyl ketone was added as the component (V), and the reaction was continued for 2 hours after heating to the second stage synthesis temperature (135 ° C.). After cooling the resulting solution, methyl isobutyl ketone was dissolved under reduced pressure of 90 ° C. and gauge pressure of −0.099 MPa to synthesize a styrene-isostearyl acrylate copolymer. A total of 105 g of methyl isobutyl ketone (component (III)) was used for washing out the weighing container when charging each material.

(Production Examples 2-3)
In Production Examples 2 to 3, styrene-isostearyl acrylate copolymer was prepared in the same manner as in Production Example 1 except that the amount of each component contained (unit: g) and the synthesis temperature were changed as shown in Table 1. A coalescence was synthesized.

(Production Example 4)
Except for changing the compounding amount of each component contained and the synthesis temperature as shown in Table 1 by changing isostearyl acrylate of Production Example 1 to lauryl acrylate (trade name: FA-112A, manufactured by Hitachi Chemical Co., Ltd.) Was synthesized in the same manner as in Production Example 1, and a styrene-lauryl acrylate copolymer was synthesized.

(Production Example 5)
Production Example 1 except that styrene of Production Example 1 was changed to benzyl acrylate (manufactured by Hitachi Chemical Co., Ltd., trade name: FA-BzA), and the amount of each component contained and the synthesis temperature were changed as shown in Table 1. In the same manner as in Example 1, a benzyl acrylate-isostearyl acrylate copolymer was synthesized.

(Production Example 6)
The styrene of Production Example 1 was changed to benzyl acrylate (manufactured by Hitachi Chemical Co., Ltd., trade name: FA-BzA), and isostearyl acrylate was changed to lauryl acrylate (manufactured by Hitachi Chemical Co., Ltd., trade name: FA-112A). A benzyl acrylate-lauryl acrylate copolymer was synthesized in the same manner as in Production Example 1 except that the amount of each component contained and the synthesis temperature were changed as shown in Table 1.

  Table 1 shows the characteristics of the copolymers obtained in Production Examples 1 to 6. Each characteristic value was evaluated by the method described below.

<Measurement of residual amount of methyl isobutyl ketone>
Measurement was performed under the following instrument measurement conditions to determine the mass of residual methyl isobutyl ketone in the synthetic resin.
Equipment used: Gas chromatography (GL Sciences)
Column: Capillary column Inert Cap WAX (inner diameter: 0.32 mm, length: 60 m)
Carrier gas: helium (95 kPa)
Inlet temperature: 200 ° C
Sample injection volume: 0.6 μL
Detector: FID (280 ° C)
Column temperature conditions: heat retention (50 ° C., 5 minutes) → temperature increase (15 ° C./minute)→heat retention (120 ° C., 10 minutes) → temperature increase (10 ° C./minute)→200° C. → temperature increase (5 ° C./minute) ) → 210 ° C. → temperature rise (1 ° C./min)→220° C. (completed)
Sample preparation: Measured sample (0.5 g) and hexane (0.1 g) as an internal standard substance are weighed into a 20 mL glass sample bottle, and then about 9.4 g of acetone (special grade manufactured by Wako Pure Chemical Industries, Ltd.) is added. The sample was prepared by dissolution.

<Measurement of weight average molecular weight and number average molecular weight>
The weight average molecular weight (Mw) and the number average molecular weight (Mn) in terms of standard polystyrene were measured under the following instrumental measurement conditions.
Equipment used: Hitachi L6000 high performance liquid chromatography (manufactured by Hitachi, Ltd., trade name)
Column: Gel pack R400, R450 and R400M (manufactured by Hitachi Chemical Co., Ltd., trade name)
Eluent: Tetrahydrofuran Column temperature: 40 ° C
Sample concentration: 0.1 g / 5 ml
Flow rate: 2ml / min
Detector: Hitachi L3350 differential refractometer (trade name, manufactured by Hitachi, Ltd.)
Under the above measurement conditions, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the copolymers obtained in Production Examples 1 to 6 were measured.

<Measurement of softening temperature>
The softening temperature was measured by a penetration mode method in thermo mechanical analysis (TMA) according to JIS K 7196 (softening temperature test method by thermomechanical analysis of thermoplastic film and sheet). Measurement equipment conditions and measurement methods are shown below.
Equipment used: EXSTAR TMA / SS6100 (trade name, manufactured by Yamato Scientific Co., Ltd.)
Probe shape: Quartz probe for penetration mode (the tip of the indenter is a cylinder with a diameter of 1.0 mm and a length of 2 mm)
Blowing gas: Indenter load blowing dry nitrogen at 50 ml / min: 50 mN
Measurement temperature: -50 to 120 ° C
Temperature rising speed: 5 ° C / min

  The sample was placed in an aluminum sample container (diameter: 5 mm, height: 2.5 mm), heated to 120 ° C. and then cooled to −50 ° C. Thereafter, the tip of the indenter of the quartz probe was gently pressed against the center of the sample with a load of 50 mN, and nitrogen gas was blown into the sample container at 50 ml / min. Thereafter, the temperature was increased from −50 ° C. to 120 ° C. at a rate of 5 ° C./min, and the change in depth (penetration amount, unit: mm) of penetration of the indenter into the sample as the sample was softened was recorded. A curve (temperature-penetration curve) was determined. The temperature at the intersection P with the extension of the tangential line of the portion where the penetration speed is maximum to the low temperature side was obtained as the softening temperature.

[Example 1]
<Preparation of adhesive sheet 1 (three-layer product)>
75 μm thick polyethylene terephthalate (made by Fujimori Kogyo Co., Ltd.) as the heavy release separator (second base material layer) 3, and 50 μm thick polyethylene as the light release separator (first base material layer) 4 and the temporary separator 6 Using terephthalate (made by Fujimori Kogyo Co., Ltd.), a pressure-sensitive adhesive sheet 1A for a photocurable image display device was produced by the following procedures (1) to (5).

  (1) 60 parts by mass of the styrene-isostearyl acrylate copolymer of Production Example 1 as a copolymer comprising a vinyl compound having an aromatic group as the component (A) and an alkyl (meth) acrylate, ( B) Compound having an ethylenically unsaturated bond as component G3000 (terminal hydroxyl group-modified polybutadiene, manufactured by Nippon Soda Co., Ltd., trade name “NISSO-PB G3000”), 10 parts by mass, component (C) having a hydrophilic group As 4HBA (4-hydroxybutyl acrylate, manufactured by Nippon Kasei Co., Ltd.) 6 parts by mass, as photopolymerization initiator of component (D) I-184 (1-hydroxycyclohexyl phenyl ketone, manufactured by BASF Japan Ltd., trade name “Irgacure” -184 ") 0.5 parts by mass, HSA (12) as an oil gelling agent for component (E) 3 parts by mass of hydroxystearic acid, manufactured by Wako Pure Chemical Industries, Ltd., and 10 parts by mass of BzA (benzyl acrylate, manufactured by Hitachi Chemical Co., Ltd., trade name “FA-BzA”), LA (lauryl acrylate, Hitachi) 14 parts by weight of Kasei Co., Ltd., trade name “FA-112A”) were weighed, sealed, and heated to 90 ° C. with a hot air circulating dryer. Then, the adhesive resin composition which was solid at normal temperature was obtained by stirring and mixing using a self-revolving stirrer.

  (2) The adhesive resin composition is applied on a heavy release separator 3 placed on a metal plate or roll heated to 40 ° C. so that the film thickness after drying is 120 μm, thereby forming a coating film. did. Subsequently, the temporary separator 6 was laminated | stacked on the said coating film, and the laminated body which pinched | interposed the adhesion layer 2 with the heavy peeling separator 3 and the temporary separator 6 was obtained.

  (3) The laminate was cut with a rotary blade having a diameter of 72 mm so as to have a length of 220 mm and a width of 180 mm.

  (4) The adhesive layer 2 and the temporary separator 6 in the cut laminate were cut with a rotary blade having a diameter of 72 mm so as to have a size of 205 mm in length and 160 mm in width. 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 on the short side of the adhesive layer 2. It cut | disconnected so that 10 mm might protrude from both sides. In the cutting in (3) and (4), a rotary punching device equipped with a rotary blade having a diameter of 72 mm was used.

  (5) The temporary separator 6 was peeled off, and a light release separator 4 having a size of 215 mm in length and 170 mm in width was laminated on the adhesive layer 2. Thus, 1 A of adhesive sheets for photocurable 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 from both sides on the short side of the adhesive layer 2. Lamination was performed so as to overhang 5 mm.

[Examples 2 to 6]
<Preparation of pressure-sensitive adhesive sheet 1A (three-layer product) for photocurable image display device>
In Examples 2-6, the adhesive sheet for photocurable image display apparatuses was carried out similarly to Example 1 except having changed the composition and compounding quantity of the component contained in an adhesive resin composition as shown in Table 2. 1A was obtained. In Table 2, the unit of the numerical value indicating the blending amount is part by mass. Each material in Table 2 is as follows.
(B) component:
G3000 (terminal hydroxyl group-modified polybutadiene, manufactured by Nippon Soda Co., Ltd., trade name “NISSO-PB G3000”)
(C) component:
4HBA (4-hydroxybutyl acrylate, manufactured by Nippon Kasei Co., Ltd.)
DMAA (N, N-dimethylacrylamide, manufactured by Wako Pure Chemical Industries, Ltd.)
(D) component:
I-184 (1-hydroxycyclohexyl phenyl ketone, manufactured by BASF Japan Ltd., trade name “Irgacure-184”)
TPO (2,4,6-trimethylbenzoyl-diphenylphosphine oxide, manufactured by BASF Japan Ltd., trade name “LUCIRIN TPO”)
(E) component:
HSA (12-hydroxystearic acid, manufactured by Wako Pure Chemical Industries, Ltd.)
Other ingredients:
BzA (benzyl acrylate, manufactured by Hitachi Chemical Co., Ltd., trade name “FA-BzA”)
LA (Lauryl acrylate, manufactured by Hitachi Chemical Co., Ltd., trade name “FA-112A”)

[Comparative Examples 1 and 2]
In Comparative Examples 1 and 2, the pressure-sensitive adhesive sheet for a photocurable image display device was the same as in Example 1 except that the composition and blending amount of the components contained in the pressure-sensitive resin composition were changed as shown in Table 3. 1A was obtained. In Table 3, the unit of the numerical value indicating the blending amount is part by mass. Moreover, each material in Table 3 is as follows.
(B) component:
TMPA (trimethylolpropane triacrylate, manufactured by Kyoeisha Chemical Co., Ltd., trade name “Light Acrylate TMPA”)
G3000 (terminal hydroxyl group-modified polybutadiene, manufactured by Nippon Soda Co., Ltd., trade name “NISSO-PB G3000”)
(C) component:
4HBA (4-hydroxybutyl acrylate, manufactured by Nippon Kasei Co., Ltd.)
(D) component:
I-184 (1-hydroxycyclohexyl phenyl ketone, manufactured by BASF Japan Ltd., trade name “Irgacure-184”)
(E) component:
HSA (12-hydroxystearic acid, manufactured by Wako Pure Chemical Industries, Ltd.)
Other ingredients:
BzA (benzyl acrylate, manufactured by Hitachi Chemical Co., Ltd., trade name “FA-BzA”)
LA (Lauryl acrylate, manufactured by Hitachi Chemical Co., Ltd., trade name “FA-112A”)

<Various evaluations>
About the adhesive sheet for photocurable image display apparatuses obtained by each Examples 1-6 and Comparative Examples 1-2, the following level | step difference embedding property, turbidity (haze), adhesiveness, and dielectric constant were evaluated. . The results are shown in Tables 2 and 3.

(Step embedding)
The step embedding property was measured by preparing an evaluation sample according to the following procedure. FIG. 24 is a schematic diagram showing a sample for evaluation of level difference embedding. First, the produced pressure-sensitive adhesive sheet for a photocurable image display device was cut into a size of 50 mm in width and 80 mm in length, and the polyethylene terephthalate film on one side of the pressure-sensitive adhesive sheet was peeled off to obtain a width of 56 mm, a length of 86 mm, and a thickness of 0. A cycloolefin polymer film having a size of 1 mm (manufactured by Nippon Zeon Co., Ltd., trade name “Zeonor film ZF16”) was bonded using a hand roller (25 ° C., load: 500 gf (4.90 N)). Next, after peeling off the polyethylene terephthalate film on the other side of the pressure-sensitive adhesive sheet for the photocurable image display device on which the cycloolefin polymer film is not bonded, a step portion D7 having a width of 9 mm and a thickness of 80 μm is formed on the outer periphery. Using a vacuum bonding apparatus (trade name “TPL-0512MH” manufactured by Takatori Co., Ltd.) so that the adhesive layer D9 is sandwiched between the glass substrate D8 having a width of 56 mm, a length of 86 mm, and a thickness of 0.7 mm. The film was bonded for 60 seconds under the conditions of 30 ° C., 0.5 MPa, and a vacuum degree of 50 Pa. Thereafter, treatment with an autoclave (30 ° C., 0.5 MPa) is performed for 30 minutes, and then ultraviolet rays are applied to the adhesive layer D9 from the cycloolefin polymer film surface side using an ultraviolet irradiation device (made by Eye Graphics Co., Ltd.). An evaluation sample was irradiated with 2.0 × 10 ³ mJ / cm ² . In FIG. 24, the illustration of the cycloolefin polymer film is omitted.

Using this evaluation sample, at 25 ° C., a laser measuring instrument (trade name “LT-9500”, manufactured by Keyence Corporation), a position controller (trade name “CP-500”, manufactured by COMS Corporation), an automatic stage ( The surface shape on the cycloolefin polymer film side was measured with a three-dimensional shape measuring device comprising a computer. The difference in height (Δt, see FIG. 24) between the portion where the step portion was provided and the portion where the step portion was not provided was measured, and the step embedding property was evaluated according to the following evaluation criteria.
A: Less than 20 μm B: 20 μm or more, less than 40 μm C: 40 μm or more

(Turbidity (haze))
The produced pressure-sensitive adhesive sheet for photocurable image display device was cut into dimensions of 40 mm in width and 100 mm in length, and the polyethylene terephthalate film on one side of the pressure-sensitive adhesive sheet for photocurable image display device was peeled off, and the width was 50 mm and length was 100 mm. The glass substrate (soda lime glass) having a thickness of 3 mm was bonded using a hand roller (25 ° C., load: 500 gf (4.90 N)). 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 used as a light source side, using a turbidimeter (trade name “NDH-5000”, manufactured by Nippon Denshoku Industries Co., Ltd.), using JIS K 7136 (plastic). -Measured according to the method for obtaining haze of transparent material).
Haze (%) = (T _d / T _t ) × 100
T _d : Diffuse transmittance T _t : Total light transmittance Further, the above sample is put into a constant temperature and humidity chamber, left in an environment of 85 ° C. and 85% RH for 500 hours, taken out, and hazeed using the above turbidimeter. Was measured.

(Adhesiveness)
The produced pressure-sensitive adhesive sheet for photocurable image display device was cut into dimensions of 25 mm in width and 25 mm in length, the polyethylene terephthalate film on one side of the pressure-sensitive adhesive sheet for photocurable image display device was peeled off, and 30 mm in width and 105 mm in length. The soda lime glass of the size of was pasted using a hand roller (25 ° C., load: 500 gf (4.90 N)). Next, the polyethylene terephthalate film on the other surface of the pressure-sensitive adhesive sheet for photocurable image display device was peeled off, and soda lime glass having a width of 30 mm and a length of 105 mm was bonded to the pressure-sensitive adhesive sheet. Using a tensile tester (Orientec Co., Ltd., trade name “RTC-1210”), the shear strength was measured at a peeling speed of 30 mm / min in a temperature environment of 25 ° C., and the adhesiveness was evaluated according to the following evaluation criteria. Evaluated. The larger the value, the better the adhesion.
A: 500 N / 25 mm □ or more B: 250 N / 25 mm □ or more, less than 500 N / 25 mm □ C: 100 N / 25 mm □ or more, less than 250 N / 25 mm □ D: less than 100 N / 25 mm □

(Dielectric constant)
The prepared pressure-sensitive adhesive sheet for a photocurable image display device was irradiated with 2000 mJ / cm ^{2 of} ultraviolet rays using an ultraviolet irradiation device, and then cut into dimensions of 50 mm in width and 50 mm in length, and a polyethylene terephthalate film on one side of the pressure-sensitive adhesive sheet was removed. It peeled off and it bonded so that the adhesive sheet might not protrude the glossy surface side of the copper foil (Nippon Electrolysis Co., Ltd. make, brand name "SLP-18") of a dimension of width 100mm, length 100mm, and thickness 18micrometer. Next, the polyethylene terephthalate film on the other side of the pressure-sensitive adhesive sheet is peeled off, and the glossy surface side of a copper foil having a width of 20 mm, a length of 20 mm, and a thickness of 18 μm (trade name “SLP-18” manufactured by Nihon Electrolytic Co., Ltd.) Were bonded so that the adhesive sheet did not protrude. A terminal is brought into contact with the center of each of a copper foil having a width of 100 mm and a length of 100 mm and a copper foil having a width of 20 mm and a length of 20 mm, and a dielectric constant measuring device (product name “LCR” manufactured by Agilent Technologies) is used. meter E4980 "), the capacitance (C) was measured under the conditions of a temperature of 25 ° C and a frequency of 100 kHz, and a dielectric constant ε _r was calculated by the following equation. Here, ε ₀ is the dielectric constant of vacuum, and d is the thickness of the adhesive layer.
C = ε ₀ × ε _r × (20 mm × 20 mm) / d

  From Tables 2 and 3, Comparative Example 1 which does not contain the compound having a hydrophilic group as the component (C) has a problem of whitening in a constant temperature and humidity test of 85 ° C., 85% RH and 500 h. Moreover, although the comparative example 2 whose compounding quantity of (C) component is 2.9 mass% on the basis of the total amount of an adhesion layer is improved from the comparative example 1 which does not add this, whitening is shown. On the other hand, Examples 1-6 whose compounding quantity of (C) component is 5-25 mass% on the basis of the total amount of an adhesion layer do not produce whitening even after a constant temperature and humidity test. And by containing (A)-(D) component, it is excellent in level | step difference embedding property, adhesiveness is favorable, and a dielectric constant shows a moderate value.

[Example 7]
<Preparation of adhesive sheet 1B>
The pressure-sensitive adhesive sheet 1B for a photocurable image display device of Example 7 was produced by the following procedures (1) to (5).
(1) In the same manner as in Example 1, an adhesive resin composition that was solid at room temperature was obtained.
(2) After coating this adhesive resin composition on one surface of the heavy release separator (second substrate layer) 3 and drying to form a coating film, the temporary separator 6 is placed on the coating film. After that, an acrylic adhesive (trade name “Hitalex K-6040”, manufactured by Hitachi Chemical Co., Ltd.) was laminated on the other surface of the heavy release separator 3, and the carrier film 5 was laminated thereon.
(3) The heavy release separator 3, the adhesive layer 2, the temporary separator 6 and the carrier film 5 were cut so as to have a length of 220 mm and a width of 180 mm.
(4) 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 have a size of 205 mm in length and 160 mm in width. For the cutting, a rotary punching device equipped with a rotary blade having a diameter of 72 mm was used. At this time, both sides on the long side of the carrier film 5 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 carrier film 5 are from both sides on the short side of the adhesive layer 2. It cut | disconnected so that it might overhang 10 mm.
(5) The temporary separator 6 is peeled off, and a light release separator (first base material layer) 4 having a size of 215 mm in length and 170 mm in width is laminated on the pressure-sensitive adhesive layer 2 to form a pressure-sensitive adhesive sheet for a photocurable image display device. 1B 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 from both sides on the short side of the adhesive layer 2. Lamination was performed so as to overhang 5 mm.

  The pressure-sensitive adhesive sheet 1B (4-layer product) was evaluated in the same manner as the above-described photo-curable image display device pressure-sensitive adhesive sheet 1A (3-layer product). As a result, a photo-curable image display device pressure-sensitive adhesive sheet having a desired shape was obtained. As in the case of Example 1, it was possible to produce the step, and the result was excellent in all of the step embedding property, turbidity (haze), adhesiveness, dielectric constant, and appearance.

  In addition, the pressure-sensitive adhesive sheets 1 of Examples 1 to 7 used in the step embedding test were peeled off and bubbled even after being left to stand for 24 hours under conditions of high temperature and high humidity (temperature 85 ° C., relative humidity 85%). Generation | occurrence | production was not observed and it confirmed that it was excellent in the reliability under high temperature, high humidity.

  According to the present invention, a pressure-sensitive adhesive layer having transparency, handleability, step embedding in a high step in a low temperature process of 45 ° C. or lower, reliability and adhesiveness under high temperature and high humidity, and excellent visibility is provided. A pressure-sensitive adhesive sheet for a photocurable image display device can be provided. Moreover, after bonding an adherend, the adhesion force and holding | maintenance force of adhesion layer itself can be improved by accelerating | stimulating the crosslinking reaction of an adhesion layer. Since a device incorporating such an adhesive layer exhibits high reliability, the photocurable image display 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 ... (for photocurable image display apparatus) Adhesive sheet (3 layer product), 1B ... (for photocurable image display apparatus) Adhesive sheet (4 layer product), 2 ... Adhesive layer, 3 ... Heavy release separator (No. 1) 2 substrate layer), 4 ... light release separator (first substrate layer), 5 ... carrier film (carrier layer), 6 ... temporary separator, 7 ... image (liquid crystal) display unit, 2a, 3a, 4a, 5a ... outer edge, 2b, 2c, 3b, 5b ... adhesive layer side surface, 3c, 5c ... notch, 10A ... base material film (three-layer product), 10B ... base material film (four-layer product), B ... Blade, 40 ... Transparent protective plate (glass or plastic substrate), 12 ... Liquid crystal display cell, 20, 22 ... Polarizing plate, 30 ... Touch panel, 31, 32 ... Transparent resin layer, 50 ... Backlight system, 60 ... Stepped part, 100: Jig, A1, A2: Deposits.

Claims (15)

(A) a copolymer comprising a vinyl compound having an aromatic group and a (meth) acrylic acid alkyl ester;
(B) a compound having an ethylenically unsaturated bond,
(C) a compound having a hydrophilic group, and (D) a pressure-sensitive adhesive layer containing a photopolymerization initiator, wherein the content of the component (C) is 5 to 25% by mass based on the total amount of the pressure-sensitive adhesive layer. A pressure-sensitive adhesive sheet for a photocurable image display device.   The pressure-sensitive adhesive sheet for a photocurable image display device according to claim 1, wherein the pressure-sensitive adhesive layer further contains (E) an oil gelling agent.   The photocurable image display according to claim 1 or 2, wherein the vinyl compound having an aromatic group in the component (A) is at least one compound selected from styrene, benzyl acrylate and benzyl methacrylate. Adhesive sheet for equipment.   The pressure-sensitive adhesive sheet for a photocurable image display device according to claim 1, wherein the (meth) acrylic acid alkyl ester in the component (A) is lauryl acrylate or isostearyl acrylate.   The pressure-sensitive adhesive sheet for a photocurable image display device according to any one of claims 1 to 4, wherein the content of the component (A) is 5 to 95% by mass based on the total amount of the pressure-sensitive adhesive layer.   The adhesive sheet for a photocurable image display device according to claim 1, wherein the adhesive layer has a haze of 1.5% or less.   The pressure-sensitive adhesive sheet for a photocurable image display device according to any one of claims 1 to 6, further comprising a first base material layer and a second base material layer laminated so as to sandwich the pressure-sensitive adhesive layer.   The carrier layer laminated | stacked on the said 2nd base material layer is further provided, The outer edge of the said 1st base material layer and the said carrier layer has protruded outside the outer edge of the said adhesion layer. Adhesive sheet for photocurable image display device. The process of sticking together adherends and obtaining a layered product through the adhesive layer with which the adhesive sheet for photocurable image display devices according to any one of claims 1 to 8 is provided, and
Heating and pressurizing the laminate under conditions of 20 to 45 ° C. and 0.1 to 0.6 MPa;
Irradiating the adhesive layer in the laminate with ultraviolet rays;
A method for manufacturing an image display device.   The method for manufacturing a photocurable image display device according to claim 9, wherein the adherend is at least two selected from the group consisting of a transparent protective plate, a touch panel, and a liquid crystal display cell.   The image display apparatus manufactured by the manufacturing method of the photocurable image display apparatus of Claim 9 or Claim 10.   The pressure-sensitive adhesive sheet for a photocurable image display device according to any one of claims 1 to 8, which is disposed between an image display unit, a transparent protective plate, and the image display unit and the transparent protective plate. An image display device comprising: the adhesive layer or a transparent resin layer made of a cured product thereof.   Image display unit, transparent protective plate, touch panel arranged between image display unit and transparent protective plate, and arranged between image display unit and touch panel, or between touch panel and transparent protective plate An image display device comprising: the pressure-sensitive adhesive layer provided in the pressure-sensitive adhesive sheet for a photocurable image display device according to any one of claims 1 to 8 or a transparent resin layer made of a cured product thereof.   The image display apparatus according to claim 12, further comprising a stepped portion that forms a step contacting the transparent resin layer on the image display unit or the transparent protective plate.   The image display device according to claim 13, further comprising a step portion that forms a step in contact with the transparent resin layer on the image display unit, the touch panel, or the transparent protective plate.

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