JP2016069529A - Adhesive sheet for image display unit, manufacturing method of image display unit and image display unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive sheet for image display unit having an adhesive layer excellent in padding property into steps formed on an article to be coated even when the steps are high, adhesiveness and reliability, and also excellent in reworkability allowing the adhesive layer to be easily removed from the article to be coated, a manufacturing method of the image display unit and the image display unit.SOLUTION: There is provided an additive sheet for image display unit having at least one adhesive layer containing (A) an acrylic polymer, (B) a crosslinking agent containing a (meth)acryloyl group, (C) a photoinitiator and (D) an ultraviolet absorber with the content of the ultraviolet absorber of 0.05 mass% to 5 mass% inclusive based on a total mass of the adhesive resin composition (adhesive layer).SELECTED DRAWING: Figure 1

Description

  The present invention relates to an adhesive sheet for an 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 is provided by printing or the like on the peripheral portion of the transparent protective plate so that these wirings cannot be seen from the transparent protective plate side (19 (frame pattern) in FIG. 1 of Patent Document 1). 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 a step are studied (for example, Patent Document 2 and Patent Document 3).

JP 2008-83491 A JP 2010-90204 A International Publication No. 2012/032995

  In recent years, for the purpose of reducing the thickness of a terminal, studies have been made to add a touch panel function to a transparent protective plate called a cover glass integrated touch panel or one glass solution (OGS). In this case, since the transparent protective plate with a touch panel function and the image display unit are bonded together with an adhesive, not only the step and wiring formed on the transparent protective plate with a touch panel function are embedded without bubbles but also to both adherends. The reliability of adhesive strength is an issue.

  In addition, when misalignment or the like occurs during bonding, the adhesive can be removed from the adherend and reused to improve the yield and reduce the waste (hereinafter also referred to as rework) is there). In this case, it is necessary to easily remove the adhesive from the adherend.

  The present invention has been made in view of the above circumstances, and includes a pressure-sensitive adhesive layer that is excellent in embedding into a step, excellent in adhesion and reliability, even when the step formed on the adherend is high. It aims at providing the adhesive sheet for image display apparatuses. In addition, an object of the present invention is to provide a pressure-sensitive adhesive sheet for an image display device, which can easily remove the pressure-sensitive adhesive layer from the adherend when the adherend is reused, and a method for manufacturing the same. Moreover, an object of this invention is to provide the manufacturing method of an image display apparatus using the adhesive sheet for image display apparatuses, and an image display apparatus.

  As a result of intensive studies by the present inventors, the adhesive layer is formed as a single layer by irradiating the sheet-shaped resin composition comprising an acrylic polymer, a crosslinking agent, an ultraviolet absorber, and a photoinitiator with ultraviolet rays. Even if it exists, it discovered that the gradient could be produced in the reaction rate of the thickness direction. That is, the surface that comes into contact with the adherend undergoes a photoreaction and can be easily removed by suppressing the tearing of the adhesive layer during reworking by imparting high strength to the adhesive layer and improving the reliability. It becomes like this. On the other hand, in the vicinity of the center of the adhesive layer in the film thickness direction, ultraviolet light is absorbed by the ultraviolet absorber, so that the photoreaction is difficult to proceed, and this allows plasticity to be added near the center of the adhesive layer, which is embedded in the step. Can increase the sex. Further, in the pressure-sensitive adhesive formed by integrating a plurality of layers, peeling between layers can occur, but in the present invention, the pressure-sensitive adhesive layer can be essentially a single layer, and such peeling does not occur. As described above, the present inventors have found that the pressure-sensitive adhesive sheet is excellent in embedding in a step and reliability, and can easily remove a pressure-sensitive adhesive layer that is unnecessary during rework. The present invention has been completed based on such findings.

  That is, the present invention has at least one adhesive layer containing (A) an acrylic polymer, (B) a crosslinking agent containing a (meth) acryloyl group, (C) a photoinitiator, and (D) an ultraviolet absorber. The adhesive sheet for image display devices in which the content of the ultraviolet absorber is 0.05% by mass or more and 5% by mass or less with respect to the total mass of the adhesive resin composition (adhesive layer).

Such an adhesive sheet for an image display device (hereinafter sometimes simply referred to as “adhesive sheet”) is excellent in embedding in a step formed on an adherend, and also has excellent surface flatness, dielectric constant and The correlated refractive index is an appropriate value, and the visibility and reliability are excellent.
The present invention also provides the above-mentioned pressure-sensitive adhesive sheet for an image display device, wherein the pressure-sensitive adhesive layer is a single layer. For the purpose of preventing peeling and peeling between layers, the adhesive layer is preferably composed of one layer.
The present invention also provides the above-mentioned pressure-sensitive adhesive sheet for an image display device, wherein the light transmittance at 365 nm of the pressure-sensitive adhesive layer is 10% or less with respect to the thickness of the pressure-sensitive adhesive layer used.
The present invention is also characterized in that the (A) acrylic polymer of the adhesive layer contains, as a copolymerization component, an alkyl acrylate having 1 to 18 carbon atoms in the alkyl group and vinyl acetate. The pressure-sensitive adhesive sheet for an image display device is provided.
The present invention also provides the above-mentioned pressure-sensitive adhesive sheet for an image display device, wherein the pressure-sensitive adhesive layer has a thickness of 10 μm to 200 μm. When used in this range, it exhibits particularly excellent effects as a transparent adhesive sheet for laminating an optical member on a display.

  Moreover, in this invention, the said adhesive sheet for image display apparatuses can further be equipped with the 1st and 2nd base material layer laminated | stacked so that the said adhesion layer may 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 image display device sheet may include a carrier layer further laminated on the second 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.
Moreover, this invention provides the manufacturing method of the adhesive sheet for image display apparatuses provided with the ultraviolet irradiation process of irradiating an ultraviolet-ray after processing an adhesive resin composition (adhesion layer) into a sheet form.
By irradiating with ultraviolet rays, the reaction rate in the thickness direction of the pressure-sensitive adhesive layer can be graded, and the surface in contact with the adherend undergoes a photoreaction, increasing the reliability by imparting high strength to the pressure-sensitive adhesive layer. It is possible to suppress the tearing of the adhesive layer at the time of reworking and to easily remove it. Near the center of the adhesive layer in the film thickness direction, ultraviolet light is absorbed by the UV absorber, making it difficult for the photoreaction to proceed, thereby providing plasticity near the center of the adhesive layer and improving the embedding in the step. Can be increased.

The present invention also includes a step of bonding the adherends to each other via an adhesive layer provided in the above-mentioned adhesive sheet for an image display device to obtain a laminate, and the laminate is 20 ° C. to 80 ° C. and 0.1 MPa to 0 MPa. The manufacturing method of an image display apparatus provided with the process heated and pressurized on 6 MPa conditions.
Moreover, this invention provides the manufacturing method of said image display apparatus whose said adherend is at least 2 sort (s) selected from the group which consists of a transparent protective plate, a touchscreen, a transparent protective plate with a touchscreen function, and a liquid crystal display cell. To do.

  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 an adhesive sheet according to an embodiment of the present invention, for example, an image display unit such as a liquid crystal display unit and a transparent protective plate with a touch panel function, the image display unit and a touch panel, the image display unit and a transparent protective plate, and a touch panel It is possible to paste together members (such as optical members) required for the image display unit and other image display devices, such as transparent protective plates. The manufacturing method according to an embodiment of the present invention is particularly useful when the adherend is an image display unit and a transparent protective plate with a touch panel function. Similarly, by using the pressure-sensitive adhesive sheet for an image display device according to an 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 this case, for example, even if the transparent protective plate on the viewing side has a high step along the outer peripheral edge, the adhesive layer can surely embed the step, so that the visibility is not lowered.

  The present invention is also an adhesive layer provided in the adhesive sheet for an image display device according to the present invention, or a cured product thereof, interposed between the image display unit, the transparent protective plate, and the image display unit and the transparent protective plate. An image display device comprising a certain transparent resin layer is provided.

  Moreover, this invention is an adhesive layer with which the adhesive sheet for image displays which concerns on the said this invention interposed between an image display unit, a touchscreen, a transparent protective board, and a touchscreen and a transparent protective board, or its hardened | cured material. And a transparent resin layer.

  The present invention also provides an image display unit, a transparent protective plate with a touch panel function, and the adhesive sheet for an image display device according to the present invention, which is interposed between the image display unit and the transparent protective plate with a touch panel function. An image display device comprising an adhesive layer or a transparent resin layer that is a cured product thereof is provided.

  The pressure-sensitive adhesive layer is excellent in step embedding into a high step, and therefore has excellent impact resistance and visibility even when a high step is provided on the image display unit, touch panel or transparent protective plate. An image display device can be obtained.

  According to the present invention, even when the step formed on the adherend is high, the pressure-sensitive adhesive layer is provided that has excellent step embedding, an appropriate dielectric constant, and excellent adhesion and visibility. An adhesive sheet for an image display device can be provided. According to the present invention, it is also possible to provide a pressure-sensitive adhesive sheet for an image display device excellent in reworkability capable of easily removing the pressure-sensitive adhesive layer from the adherend and a method for producing the same. 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 image display apparatuses. It is sectional drawing which shows one Embodiment of the adhesive sheet for 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. It is sectional drawing which shows the sticking process of the adhesion surface to a to-be-adhered body. It is sectional drawing which shows the peeling process of a heavy peeling separator. It is sectional drawing which shows the sticking process of the adhesion surface to a to-be-adhered body. It is a perspective view which shows one Embodiment of the adhesive sheet for image display apparatuses. It is a side view which shows one Embodiment of the adhesive sheet for 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.

  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” or “methacrylate” corresponding thereto. Similarly, “(meth) acryl” means “acryl” or “methacryl” corresponding thereto, and “(meth) acryloyl” means “acryloyl” or “methacryloyl” corresponding thereto.

[First embodiment]
<Adhesive sheet for image display device>
The pressure-sensitive adhesive sheet for an image display device according to the present embodiment preferably includes a pressure-sensitive adhesive layer and a pair of base material layers laminated so as to sandwich the pressure-sensitive adhesive layer. Moreover, it is preferable that the outer edge of the said base material layer protrudes outside the outer edge of the said adhesion layer.

  That is, as shown in FIG. 1 and FIG. 2, the pressure-sensitive adhesive sheet 1 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 may overhang 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 pressure-sensitive adhesive sheet 1 according to the present embodiment is used for an image display device, the haze (Haze, turbidity) of the pressure-sensitive adhesive layer 2 is usually 1.5% or less. From the viewpoint of visibility, the haze of the pressure-sensitive adhesive layer 2 is preferably 1.0% or less, more preferably 0.8% or less, and still more preferably 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 components (A), (B), (C), and (D) described later. When the compatibility among 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. The total transmittance T _{t of} light irradiated through a lamp and transmitted through the sample, and the transmittance T _{d of} light diffused and scattered in the sample. Therefore, it is obtained as (T _d / T _t ) × 100. These are defined by JIS K 7136, and can be easily measured using a commercially available turbidimeter, for example, NDH-5000 manufactured by Nippon Denshoku Industries Co., Ltd.

The thickness of the pressure-sensitive adhesive layer 2 is not particularly limited because it is appropriately adjusted depending on the intended use and method, but is 10 μm to 2.0 × 10 ² μm, 25 μm to 1.8 × 10 ² μm, or 50 μm to 1.5 × 10. ^It may be ² μm. When used in this range, it exhibits particularly excellent effects as a transparent adhesive sheet for laminating an optical member on a display.

10% or more is preferable, 20% or more is more preferable, and 50% is the minimum value of the light transmittance with respect to the light in the visible light region (wavelength: 380 nm to 780 nm) of the adhesive layer 2 having a thickness suitable for the image display device. The above is more preferable. In particular, the minimum value of the light transmittance for light having a wavelength of 400 nm to 780 nm is preferably 90% or more from the viewpoint of visibility.
On the other hand, the light transmittance of the pressure-sensitive adhesive layer 2 having a thickness suitable for an image display device with respect to light having a wavelength of 365 nm is preferably 10% or less, more preferably 5% or less from the viewpoint of easy control of the reaction rate in the thickness direction. 1% or less is more preferable. The light transmittance can be easily measured using a commercially available ultraviolet-visible spectrophotometer, for example, V-570 manufactured by JASCO Corporation.

  The pressure-sensitive adhesive layer 2 is a pressure-sensitive adhesive layer (adhesive resin) containing (A) an acrylic polymer, (B) a crosslinking agent containing a (meth) acryloyl group, (C) a photo (polymerization) initiator, and (D) an ultraviolet absorber. The adhesive layer is preferably composed of one layer for the purpose of preventing peeling and peeling between layers. Hereinafter, each component will be described.

[(A): Acrylic polymer]
(A) Acrylic polymer refers to a polymer obtained by polymerizing one type of monomer having one (meth) acryloyl group in the molecule, or by copolymerizing two or more types in combination. In addition, if it is a range which does not impair the effect of this embodiment, (A) component is a compound which has 2 or more of (meth) acryloyl groups in a molecule | numerator, or a polymerizable compound which does not have a (meth) acryloyl group (Compounds having one polymerizable unsaturated bond in the molecule such as acrylonitrile, styrene, vinyl acetate, ethylene, propylene, etc., and compounds having two or more polymerizable unsaturated bonds in the molecule such as divinylbenzene) It may be copolymerized with a coalescence.

  (A) As a monomer which has one (meth) acryloyl group in a molecule | numerator which forms a component, (meth) acrylic acid; (meth) acrylic acid amide; (meth) acryloylmorpholine; methyl (meth) acrylate, Ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) Carbon number of alkyl group such as acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate (n-lauryl (meth) acrylate), stearyl (meth) acrylate, etc. ~ 18 Archi (Meth) acrylate; (meth) acrylate having an aromatic ring such as benzyl (meth) acrylate, phenoxyethyl (meth) acrylate; cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, etc. (Meth) acrylate having an alicyclic group; tetrahydrofurfuryl (meth) acrylate; N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, N, N-dimethyl (meta) ) Acrylamide, N-isopropyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, (meth) acrylamide derivatives such as N-hydroxyethyl (meth) acrylamide; 2- (2-methacryloyloxyethyloxy) Ethyl isocyanate, 2- (meth) acrylate having an isocyanate group of acryloyloxyethyl isocyanate (meth) acrylates, and alkylene glycol chain-containing (meth) acrylate.

  From the viewpoint of giving moderate flexibility to the adhesive layer, absorbing damage from the outside world when the image display device is bonded, preventing damage, and preventing distortion of the image due to distortion, the component (A) is Among the compounds, n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferably contained.

  From the viewpoint of increasing the adhesive strength, the component (A) preferably contains vinyl acetate among the above compounds. The content ratio of the vinyl acetate is preferably 1% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass or more based on the total mass of the copolymerized polymer. . Moreover, it is preferable that it is 50 mass% or less, It is more preferable that it is 30 mass% or less, It is still more preferable that it is 25 mass% or less. When the content ratio of vinyl acetate is within this range, the adhesion between the adhesive layer and the transparent protective plate (glass substrate, plastic substrate, etc.) and the step embedding property can be further improved.

  When making the dielectric constant of an adhesion layer low, it is preferable that (A) component contains stearyl (meth) acrylate among the said compounds. The content ratio of the stearyl (meth) acrylate is preferably 50% by mass or more, more preferably 60% by mass or more, and 70% by mass or more with respect to the total mass of the copolymerized polymer. Is more preferable. Moreover, it is preferable that it is 95 mass% or less, and it is more preferable that it is 90 mass% or less. When the content ratio of stearyl (meth) acrylate is in such a range, the dielectric constant can be adjusted to an appropriate range. In general, a polymer having such a copolymerization ratio can be obtained by blending each monomer in the same ratio as the above-mentioned copolymerization ratio and copolymerizing them. The polymerization rate is more preferably substantially close to 100% by mass.

  Examples of stearyl (meth) acrylate include n-stearyl (meth) acrylate (also referred to as octadecyl (meth) acrylate), isostearyl (meth) acrylate (also referred to as 16-methylheptadecyl (meth) acrylate), and the like. Among these, isostearyl (meth) acrylate is more preferable. These stearyl (meth) acrylates may be used in combination of two or more.

  Moreover, the alkylene glycol chain containing (meth) acrylate shown by following General formula (1) can also be used together as a monomer which has one (meth) acryloyl group which forms (A) component in a molecule | numerator.

一般式（１）中、Ｘは水素原子又はメチル基を示し、Ｒは水素原子又は炭素数１〜１０のアルキル基を示し、ｐは２〜４の整数を示し、ｑは１〜１０の整数を示す。

In general formula (1), X represents a hydrogen atom or a methyl group, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, p represents an integer of 2 to 4, and q represents an integer of 1 to 10 Indicates.

Examples of the alkylene glycol chain-containing (meth) acrylate represented by the general formula (1) include 2-hydroxyethyl (meth) acrylate, 1-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 3-hydroxy Propyl (meth) acrylate, 1-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 1-hydroxybutyl (meth) acrylate Hydroxyl group-containing (meth) acrylates such as: diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, hexaethylene glycol Polyethylene glycol mono (meth) acrylates such as (meth) acrylate; polypropylene glycol mono (meth) acrylates such as dipropylene glycol mono (meth) acrylate, tripropylene glycol mono (meth) acrylate and octapropylene glycol mono (meth) acrylate; Polybutylene glycol mono (meth) acrylates such as dibutylene glycol mono (meth) acrylate and tributylene glycol mono (meth) acrylate; methoxytriethylene glycol (meth) acrylate, methoxytetraethylene glycol (meth) acrylate, methoxyhexaethylene glycol (Meth) acrylate, methoxyoctaethylene glycol (meth) acrylate, methoxynonaethylene glycol ( ) Alkoxypolyalkylene glycols such as acrylate, methoxypolyethylene glycol (meth) acrylate, methoxyheptapropylene glycol (meth) acrylate, ethoxytetraethylene glycol (meth) acrylate, butoxyethylene glycol (meth) acrylate, butoxydiethylene glycol (meth) acrylate Examples include (meth) acrylate.
Among these, 2-hydroxyethyl (meth) acrylate, 1-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 1-hydroxypropyl (meth) acrylate, 4 -Hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 1-hydroxybutyl (meth) acrylate are preferred, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate is more preferable, and 2-hydroxyethyl (meth) acrylate is more preferable. These alkylene glycol chain-containing (meth) acrylates may be used in combination of two or more.

  From the viewpoint of suppressing whitening (cloudiness) due to absorbed moisture when the adhesive layer is exposed to high temperature and humidity conditions, the component (A) is 2-hydroxyethyl (meth) acrylate among the above compounds. It is preferable to contain. The content ratio of 2-hydroxyethyl (meth) acrylate is preferably 1% by mass or more, more preferably 2% by mass or more, and more preferably 4% by mass or more with respect to the total mass of the copolymerized polymer. More preferably it is. Moreover, it is preferable that it is 30 mass% or less, It is more preferable that it is 25 mass% or less, It is still more preferable that it is 20 mass% or less. When the content ratio of 2-hydroxyethyl (meth) acrylate is within this range, even when the pressure-sensitive adhesive layer is exposed to high temperature and humidity conditions, whitening does not occur and the dielectric constant can be set to an appropriate value.

The weight average molecular weight of the component (A) is preferably 1.0 × 10 ⁵ or more, more preferably 2.0 × 10 ⁵ or more, and further preferably 3.0 × 10 ⁵ or more. . When the weight average molecular weight of the component (A) is 1.0 × 10 ⁵ or more, it is possible to obtain an adhesive layer having an adhesive force that is less likely to be peeled off from the transparent protective plate or the like. On the other hand, the weight average molecular weight of the component (A) is preferably 2.0 × 10 ⁶ or less, more preferably 1.0 × 10 ⁶ or less, and 8.0 × 10 ⁶ or less. Further preferred. When the weight average molecular weight of the component (A) is 2.0 × 10 ⁶ or less, the viscosity of the adhesive resin composition does not become too high, and the processability when forming a sheet-like adhesive layer becomes better.
The weight average molecular weight is a value converted by gel permeation chromatography (GPC) using a standard polystyrene calibration curve. The measurement conditions for the weight average molecular weight are the same as those in the examples of the present specification.

  As the polymerization method for obtaining the acrylic polymer of component (A), known polymerization methods such as solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization and the like can be used.

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

  The content of the component (A) is preferably 80% by mass or more, more preferably 90% by mass or more, and 95% by mass or more with respect to the total mass of the adhesive resin composition. Further preferred. Moreover, it is preferable that it is 99.9 mass% or less, it is more preferable that it is 99.8 mass% or less, and it is still more preferable that it is 99.5 mass% or less. When the content of the component (A) is within this range, the obtained adhesive layer has better adhesion to a transparent protective plate such as a glass substrate or a plastic substrate, and better step embedding.

[Component (B): Cross-linking agent having a (meth) acryloyl group]
Specific examples of the cross-linking agent having a (meth) acryloyl group as the component (B) include pentaerythritol triacrylate, ethoxylated isocyanuric acid triacrylate, ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate, and ethoxylation. Glycerin triacrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol poly (di, tri, tetra, penta) acrylate, dipentaerythritol hexaacrylate, dimethylol -Bifunctional or polyfunctional (meth) acrylates such as tricyclodecanediacrylate are excellent in film shape stability and adhesive strength It can be suitably used from the.
The content of such polyfunctional (meth) acrylates is preferably 0.1% by mass to 10% by mass, and 0.2% by mass to 5% by mass with respect to the total mass of the adhesive resin composition. % Is more preferable. When the content is within this range, the step embedding property and the adhesive strength at high temperatures can be enhanced.

  In addition, as component (B), polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, EO-modified bisphenol A di (meth) acrylate (EO represents ethylene oxide), polytetramethylene glycol di (meth) Di (meth) acrylates such as acrylate can be used, and specifically, compounds represented by the following general formulas (2) to (7) can be preferably used. In general formulas (2), (3), and (4), s represents an integer of 1 to 20, and in general formulas (5) and (6), m and n each independently represents an integer of 1 to 10. Show. The content of such di (meth) acrylates is preferably 0.1% by mass to 10% by mass, and preferably 0.2% by mass to 5% by mass with respect to the total mass of the adhesive resin composition. It is more preferable that When the content is within this range, the step embedding property and the adhesive strength at high temperatures can be enhanced. In particular, a compound having a polyethylene glycol skeleton such as polyethylene glycol di (meth) acrylate and EO-modified bisphenol A di (meth) acrylate does not whiten even when the adhesive layer is exposed to high temperature and humidity conditions, and has a dielectric constant. Can be set to an appropriate value.

In addition, as the component (B), urethane (meth) acrylate having a urethane bond, side chain (meth) acryl-modified (meth) acrylate polymer, and the like can be suitably used.
The urethane di (meth) acrylate having a urethane bond preferably has a polyalkylene glycol chain from the viewpoint of good compatibility with other components. Moreover, it is preferable to have an alicyclic structure from a viewpoint of ensuring transparency. When the compatibility between the component (A), the component (B) and the component (C) is low, the cured product may become cloudy.
The side chain (meth) acryl-modified (meth) acrylate polymer may be a (meth) acrylate polymer having a side chain modified with a (meth) acryloyl group, but a structural unit represented by the following general formula (8), and It is preferable to have a structural unit represented by the following general formula (9), and the (meth) acrylate polymer before modification is more preferably the component (A). By (meth) acrylic modification of the side chain of the component (A) to make the component (B), the structures of the component (A) and the component (B) are almost equal, so the compatibility is excellent and turbidity (haze) A highly transparent pressure-sensitive adhesive sheet can be obtained.
As a method for modifying the side chain by (meth) acryl, for example, a structural unit having a hydroxyl group represented by the following general formula (10) or a structural unit having a carboxyl group is added to the component (A) in the main chain of the polymer. There is a method of adding (meth) acrylate having an isocyanate group such as 2-isocyanatoethyl (meth) acrylate represented by the following general formula (11). As another method, for example, there is a method in which a structural unit having a glycidyl group as represented by the following general formula (12) is provided in the main chain of the polymer and (meth) acrylic acid is added thereto. Can be mentioned. Furthermore, although the method of forming a (meth) acryl side chain by graft polymerization is also mentioned, it has isocyanate groups, such as 2-isocyanatoethyl (meth) acrylate, in the hydroxyl group as shown by the following general formula (10) ( A method of adding (meth) acrylate or a method of adding (meth) acrylic acid to a glycidyl group as shown by the following general formula (12) is more preferable.
When (meth) acrylate having an isocyanate group is added to a hydroxyl group as represented by the following general formula (10), 0.01 equivalent to 0 (meth) acrylate having an isocyanate group is added to 1 equivalent of the hydroxyl group. It is preferable to add such that the ratio is .9 equivalents. Similarly, when (meth) acrylic acid is added to a glycidyl group as represented by the following general formula (12), 0.01 equivalent to 0.9 equivalent of (meth) acrylic acid per 1 equivalent of glycidyl group. It is preferable to add so that it may become a ratio.
According to these methods, a structure in which the side chain (meth) acryloyl group is bonded to the main chain via a urethane bond or an ester bond is obtained. These structures are preferable from the viewpoints of impact absorption, low dielectric constant and the like.

（一般式（８）中、Ｒは水素あるいはメチル基を表し、Ｒ^１は炭素数４〜１８のアルキル基あるいは脂環式アルキル基を表す。）

(In General Formula (8), R represents hydrogen or a methyl group, and R ¹ represents an alkyl group having 4 to 18 carbon atoms or an alicyclic alkyl group.)

（一般式（９）中、Ｒは水素あるいはメチル基を表し、Ｘは、−ＣＨ_２ＣＨ_２−、−（ＣＨ_２ＣＨ_２Ｏ）_ｐＣＨ_２ＣＨ_２−｛ｐは１〜５００までの整数｝、−Ｒ^２−ＯＣＯＮＨ−Ｒ^３−あるいは−Ｒ^４−ＣＨ（ＯＨ）ＣＨ_２−を表し、Ｒ^２、Ｒ^３及びＲ^４はそれぞれ独立に炭素数１〜１０のアルキレン基あるいは脂環式アルキレン基を表す。）

(In formula (9), R represents hydrogen or a methyl group, X _{is, -CH 2 CH 2 -, -} (CH 2 CH 2 O) p CH 2 CH 2 - {p is an integer from 1 to 500 }, —R ² —OCONH—R ³ — or —R ⁴ —CH (OH) CH ₂ —, wherein R ² , R ³ and R ⁴ are each independently an alkylene group or alicyclic group having 1 to 10 carbon atoms. Represents an alkylene group.)

（一般式（１０）中、Ｒは水素あるいはメチル基を表し、Ｒ^２は炭素数１〜１０のアルキレン基あるいは脂環式アルキレン基を表す。）

(In general formula (10), R represents hydrogen or a methyl group, and R ² represents an alkylene group having 1 to 10 carbon atoms or an alicyclic alkylene group.)

（一般式（１１）中、Ｒは水素あるいはメチル基を表し、Ｒ^３は炭素数１〜１０のアルキレン基あるいは脂環式アルキレン基を表す。）

(In general formula (11), R represents hydrogen or a methyl group, and R ³ represents an alkylene group having 1 to 10 carbon atoms or an alicyclic alkylene group.)

（一般式（１２）中、Ｒは水素あるいはメチル基を表し、Ｒ^４は炭素数１〜１０のアルキレン基あるいは脂環式アルキレン基を表す。）

(In general formula (12), R represents hydrogen or a methyl group, and R ⁴ represents an alkylene group having 1 to 10 carbon atoms or an alicyclic alkylene group.)

Further, the weight average molecular weight when the side chain (meth) acryl-modified (meth) acrylate polymer is used as the component (B) is preferably the same as that of the component (B), but the weight average molecular weight is somewhat low because of the side chain modification. Can also be used. Specifically, 1.0 × 10 ⁴ or more is preferable, 1.5 × 10 ⁴ or more is more preferable, 2.0 × 10 ⁴ or more is further preferable, and 2.5 × 10 ⁴ or more is particularly preferable. From the same viewpoint, it is preferably 3.0 × 10 ⁵ or less, more preferably 1.0 × 10 ⁵ or less, still more preferably 8.0 × 10 ⁴ or less, and 7.0 × It is particularly preferred that it is 10 ⁴ or less.

  (B) When using a urethane (meth) acrylate having a urethane bond as a component, a side chain (meth) acryl-modified (meth) acrylate polymer, etc., the optimum content varies depending on the modification rate of the side chain, but the content If the amount is too large, the pressure-sensitive adhesive layer becomes hard and air bubbles tend to enter the stepped portion. On the other hand, if the amount is too small, the holding power at high temperatures tends to be low and the reliability tends to decrease.

  In the case of using a urethane (meth) acrylate having a urethane bond as the component (B), a side chain (meth) acryl-modified (meth) acrylate polymer, or the like, there is no particular limitation on the lower limit of the content, but the dimensional stability of the film is improved. From a viewpoint of making it more favorable, it is preferable that it is 0.1 mass% or more, It is more preferable that it is 0.2 mass% or more, It is still more preferable that it is 0.5 mass% or more. (B) It is preferable that content of a component is 15 mass% or less with respect to the total mass of an adhesive resin composition. When the content is 15% by mass or less, since the crosslinking density does not become too high, an adhesive layer having more sufficient adhesiveness, high elasticity, and no brittleness can be obtained. From the viewpoint of further improving the step embedding property, the content of the component (B) is more preferably 10% by mass or less, and further preferably 7% by mass or less.

[(C) component: photoinitiator]
The photoinitiator of component (C) may be a hydrogen abstraction type photoinitiator. The hydrogen abstraction type photoinitiator is a component that accelerates the curing reaction by irradiation with active energy rays. Here, active energy rays refer to ultraviolet rays, electron beams, α rays, β rays, γ rays and the like. From the viewpoint of easy production, ultraviolet rays are preferred, and ultraviolet rays of 360 nm to 380 nm are particularly preferred because they can increase the reaction rate difference of (meth) acryloyl groups in the depth direction of the adhesive layer. Examples of hydrogen abstraction type initiators include benzophenone, its derivatives, and thioxanthone. Benzophenone and its derivatives can improve the curing rate by using a tertiary amine as a hydrogen donor.

  Component (C) may use other photoinitiators, and is not particularly limited as a photoinitiator, and materials such as benzophenone, anthraquinone, benzoyl, sulfonium salt, diazonium salt, onium salt are used. Is possible.

  Specific examples of the photoinitiator include benzophenone, 4-methylbenzophenone, 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-dichloroanthraquinone, 3-chloro-2-methylanthraquinone, 1,2-benzoanthraquinone, 2-phenylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, thioxanthone, 2-chlorothioxanthone, 1 -Hydroxycyclohexylphen Aromatic ketone compounds such as luketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-diethoxyacetophenone; Benzoin compounds such as benzoin, methylbenzoin, and ethylbenzoin; 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- (acridine-9- Yl) ester compounds such as (meth) acrylic acid; acridine compounds such as 9-phenylacridine, 9-pyridylacridine, 1,7-diacridinoheptane; 2- (o-chlorophenyl) -4,5-diphenylimidazole 2- (o-chlorophenyl) -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 2,4,5- such as 2- (2,4-dimethoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methylmercaptophenyl) -4,5-diphenylimidazole dimer Triarylimidazole dimer; 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone; 2-methyl-1- [4- (methylthio ) Phenyl] -2-morpholino-1-propane; bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide; oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl)) Phenyl) propanone) and the like. These compounds may be used in combination.

  In particular, as the component (C), benzophenone and 4-methylbenzophenone are preferable from the viewpoint of enhancing the adhesive strength at high temperatures.

  The content of the component (C) is preferably 0.05% by mass or more, and more preferably 0.1% by mass or more with respect to the total mass of the adhesive resin composition (adhesion layer). From the same viewpoint, the content of the component (C) is preferably 5% by mass or less, more preferably 3% by mass or less, with respect to the total mass of the adhesive resin composition (adhesive layer). More preferably, it is 2 mass% or less. When the content of component (C) is within these ranges, the effect of exuding and excellent reliability under high temperature and high humidity can be obtained more remarkably. Furthermore, when the content of the component (C) is 5% by mass or less, an adhesive layer having a higher light transmittance, a hue that is not yellowish, and excellent in step embedding is obtained. Can do.

[(D) component: UV absorber]
The component (D) is important for inclining the reaction rate of the (meth) acryloyl group in the thickness direction by absorbing a part of the irradiated ultraviolet light and controlling the reaction of the photoinitiator. As such an ultraviolet absorber, any compound that has absorption in the same wavelength region as the photoinitiator or the ultraviolet rays to be irradiated can be used. Specifically, benzotriazole-based ultraviolet absorbers (for example, ADEKA CORPORATION's ADEKA STAB LA-29, LA-31, LA-32, LA-36, “ADEKA STAB” is a registered trademark), benzophenone-based ultraviolet absorbers (for example, ADEKA Corporation Adeka Stub 1413), triazine ultraviolet absorbers (for example, Adeka Corporation Adeka Stub LA-46, LA-F70) and the like can be used.

  (D) Content of a component is 0.05 mass% or more with respect to the total mass of an adhesive resin composition (adhesion layer), and 0.1 mass% or more is preferable. From the same viewpoint, the content of the component (D) is 5% by mass or less, preferably 3% by mass or less, and preferably 2% by mass with respect to the total mass of the adhesive resin composition (adhesive layer). The following is more preferable. When the content of the component (D) is within these ranges, the light transmittance at 365 nm of the pressure-sensitive adhesive layer 2 can be 10% or less, and as a result, a pressure-sensitive adhesive layer having excellent step embedding can be produced. .

[Other ingredients]
In addition to the above components (A), (B), (C), and (D), the adhesive resin composition may contain an acrylic monomer and various additives as necessary. 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.

  In particular, the addition of a silane coupling agent is preferable because the decrease in adhesive force is suppressed even when exposed to high temperature and high humidity. Examples of such silane coupling agents include vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-methacryloxypropylmethyl. Diethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-aminopropyltriethoxysilane can be suitably used.

  The amount of the silane coupling agent added is preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more. Moreover, it is preferable that it is 5 mass% or less, it is more preferable that it is 2 mass% or less, and it is still more preferable that it is 1 mass% or less. When the content of the silane coupling agent is within this range, the obtained adhesive layer has better adhesiveness after exposure to high temperature and high humidity.

[Processing method of adhesive sheet or adhesive film]
A well-known technique can be used as a method of processing the adhesive resin composition into a sheet or film. For example, the above-mentioned adhesive resin composition is diluted with a ketone solvent such as methyl ethyl ketone and cyclohexanone to prepare a coating solution, and then the coating solution is applied to a substrate such as a polymer film by a flow coating method, a roll Coating is performed by a 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.

  In preparing the coating liquid, it can be diluted with a solvent after blending each component, or can be diluted with a solvent in advance before blending each component.

  From the viewpoint of coating properties, the solid content concentration of the coating liquid is preferably 30% by mass or more, and more preferably 40% by mass or more. From the same viewpoint, the solid content concentration of the coating liquid is preferably 70% by mass or less, and more preferably 60% by mass.

  From the viewpoint of coating properties, the viscosity (25 ° C.) of the coating liquid is preferably 1 Pa · s or more, and more preferably 2 Pa · s or more. From the same viewpoint, it is preferably 30 Pa · s or less, more preferably 25 Pa · s or less, and further preferably 2 to 15 Pa · s.

The thickness of the adhesive layer may be a 10μm~3.0 × 10 ² μm, from the viewpoint of thinning the device, preferably 10μm~2.0 × 10 ² μm.

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

  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 (A), (B), (C), and (D) above, and generally the total mass of the adhesive resin composition. It is 0.01 mass%-5 mass% with respect to it.

The heavy release separator 3 (second base material layer) may be, for example, a polyester film such as polyethylene terephthalate, or a polymer film such as polypropylene or polyethylene. The heavy release separator 3 can be a PET film. From the viewpoint of workability, the thickness of the heavy release separator 3 may be 50 μm to 2.0 × 10 ² μm, 60 μm to 1.5 × 10 ² μm, or 70 μm to 1.3 × 10 ² μm.

  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 the portion protruding from the outer edge of the adhesive layer 2 may be 2 mm to 20 mm or 4 mm to 10 mm from the viewpoint of ease of handling, ease of peeling, and reduction of 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 mm to 20 mm on at least one side. Alternatively, it may be 4 mm to 10 mm, or 2 mm to 20 mm or 4 mm to 10 mm on all sides.

Examples of the light release separator 4 (first base material layer) include polymer films such as polyester such as polyethylene terephthalate, polypropylene, and polyethylene. The light release separator 4 can be a PET film. The thickness of the light release separator 4 may be 25 μm to 1.5 × 10 ² μm, 30 μm to 1.0 × 10 ² μm, or 40 μm 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 pressure-sensitive adhesive layer 2 may be set to 2 mm to 20 mm or 4 mm 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 mm to 20 mm or 4 mm to 10 mm, or may be 2 mm to 20 mm or 4 mm to 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.
A pressure-sensitive adhesive sheet comprising a first base material layer (light release separator) and a second base material layer (heavy release separator) laminated so as to sandwich the pressure-sensitive adhesive layer includes an ultraviolet irradiation process for irradiating ultraviolet light, and is a pressure-sensitive adhesive sheet. Irradiate ultraviolet rays on both sides. The ultraviolet irradiation may be performed on one side. By irradiating with ultraviolet rays, the reaction rate in the thickness direction of the pressure-sensitive adhesive layer can be graded, and the surface in contact with the adherend undergoes a photoreaction, increasing the reliability by imparting high strength to the pressure-sensitive adhesive layer. It is possible to suppress the tearing of the adhesive layer at the time of reworking and to easily remove it. Near the center of the adhesive layer in the film thickness direction, ultraviolet light is absorbed by the UV absorber, making it difficult for the photoreaction to proceed, thereby providing plasticity near the center of the adhesive layer and improving the embedding in the step. Can be increased. The amount of UV irradiation is determined in consideration of the blending amount of the adhesive resin composition, embedding property, reliability, and peelability. Generally, it is 4.0 × 10 ² mJ / cm ^{2 to} 8.0 × 10 ² mJ / cm ² on one side.

<Method for producing pressure-sensitive adhesive sheet for image display device>
The adhesive sheet 1 demonstrated above can be manufactured by the following methods, for example. First, as shown in FIG. 3, a base film 10 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 1 is completed through the above steps.

<Image display device>
Next, an image display device manufactured using the adhesive sheet 1 will be described. The pressure-sensitive adhesive layer 2 included in the pressure-sensitive adhesive sheet 1 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 (meth) acrylate and an epoxy acrylate; base materials films, such as a polyethylene film, can be used, for example. Similarly, in order to increase the surface hardness, a transparent protective plate made of glass, acrylic resin, polycarbonate, or the like with a hard coat layer formed or laminated can be used.

  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 and / 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. The step 60 due to the decorative portion varies depending on the size of the liquid crystal display device, etc., but when the height is ²⁰ μm to 1.0 × 10 ² μm, particularly 35 μm to 65 μm, the adhesive layer of this embodiment may be used. It is particularly useful. 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 stepped portion is h and the thickness of the transparent resin layer is t, even if 0.25 <(h / t) <1, excellent step embedding properties are exhibited.

  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 which is a decorative portion 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, metal oxides, such as ITO (Indium Tin Oxide), are mentioned, for example. The thickness of the substrate is 20 μm to 1.0 × 10 ³ μm. The transparent electrode has a thickness of 10 nm to 5.0 × 10 ² nm.

The thickness of the transparent resin layer 31 or 32 may be, for example, 0.01 mm to 3 mm or 50 μm to 2.0 × 10 ² 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 plates such as glass substrates and quartz plates; plastic substrates such as acrylic resin substrates, polycarbonate plates and cycloolefin polymer plates; resin sheets such as thick polyester sheets. When high surface hardness is required, 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.

<Method for Manufacturing Image Display Device>
The pressure-sensitive adhesive sheet 1 is used as follows in assembling an image display device or the like. First, as shown in FIG. 10, the light release separator 4 is peeled from the pressure-sensitive adhesive sheet 1 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. When the adhesive layer 2 is pressed against the adherend A1, the adherend A1 that may heat the adhesive layer 2 to 30 ° C. to 80 ° C. is, for example, an image display unit, a transparent protective plate, a transparent protective plate with a touch panel function, It is a liquid crystal display cell 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.
The conditions for heating and pressurizing the laminate are, for example, a temperature of 20 ° C. to 80 ° C. and a pressure of 0.1 MPa to 0.6 MPa. When the step on the surface of the adherend is 40 μm to 1.0 × 10 ² μm, since the bubbles near the step can be more efficiently removed, the temperature is 50 to 70 ° C., and the pressure is 0.2 MPa to 0.2 MPa. It may be 5 MPa. The time of heating and pressurization may be 5 minutes to 60 minutes, or 10 minutes 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 stepped portion 60 is light-shielding, in the present invention, in addition to the above-described ultraviolet irradiation, the stepped portion 60 and the adherend A2 (for example, a transparent protective plate, a touch panel) are viewed from the side surface of the laminate shown in FIG. It is preferable to irradiate ultraviolet rays toward the adhesive resin composition of the adhesive layer 2 in the region located between the two. 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 The tensile shear strength at 85 ° C. is preferably 0.10 MPa or more, more preferably 0.16 MPa or more, and further preferably 0.24 MPa or more. When the shear strength at 85 ° C. is in this range, it is possible to suppress problems such as displacement between the substrates and bubbles in the high temperature test. The tensile shear strength is determined by a tensile test on a sample that has been bonded to two substrates with an adhesive layer having a width of 25 mm and a length of 25 mm, and then subjected to the heating and pressurization and, if necessary, ultraviolet irradiation to the adhesive layer. Measured using a machine ("Tensilon RTC-1210" manufactured by Orientec Co., Ltd., "Tensilon" is a registered trademark) at a tensile speed of 30 mm / min and a measurement temperature of 85 ° C, and divide the maximum load at break by the adhesive area Can be obtained.

  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 can be manufactured by obtaining the laminate by interposing the adhesive layer 2 of the present embodiment between the image display unit and the touch panel, or between the touch panel and the transparent protective plate. .

[Second Embodiment]
<Adhesive sheet for image display device>
The pressure-sensitive adhesive sheet 1 for an image display device according to this embodiment is further laminated on 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 base material layer. And the outer edges of the first base material layer and the carrier layer project outward from the outer edge of the adhesive layer.

  That is, as shown in FIGS. 14 and 15, the pressure-sensitive adhesive sheet 1 according to the present embodiment includes a transparent film-like pressure-sensitive adhesive layer 2 and a light release separator 4 (first film) that is laminated so as to sandwich the pressure-sensitive adhesive layer 2. ) And a heavy release separator 3 (second base material layer), and a carrier film 5 (carrier layer) further laminated on the heavy release separator 3.

  The outer edge 5 a of the carrier film 5 may protrude 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 mm to 10 mm or 1 mm to 5 mm from the viewpoint of ease of handling, ease of peeling, and reduction of 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 mm to 10 mm or 1 mm to 5 mm on at least one side, or 0.5 mm to 10 mm or 1 mm to 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 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 μm to 100 μm, 20 μm to 80 μm, or 20 μm 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 by, for example, providing an adhesive layer 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 μm to 10 μm or 1 μm to 5 μm.

  As described above, according to the pressure-sensitive adhesive sheet 1 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 image display device>
For example, the pressure-sensitive adhesive sheet 1 of the present embodiment is manufactured as follows. First, as shown in FIG. 16, a base material film 10 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 part of the temporary separator 6 and the adhesive layer 2 is removed, and the outer part of the heavy release separator 3 is left on the carrier film 5 without being removed. The heavy release separator 3 after cutting is attached to the carrier film 5 as it is. It 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 1 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 1 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 sheets according to the first embodiment and the second embodiment are produced, but the present invention is not limited to these examples.

Component (A): Synthesis of acrylic polymer acrylic polymer (A-1) 157.5 g of 2-ethylhexyl acrylate as an initial monomer in a reaction vessel equipped with a cooling tube, a thermometer, a stirrer, a dropping funnel and a nitrogen introducing tube Then, 42.0 g of vinyl acetate, 10.5 g of acrylic acid, and 285 g of ethyl acetate were taken and heated from room temperature (25 ° C.) to 80 ° C. for 15 minutes while replacing with nitrogen at an air volume of 100 ml / min. Then, while maintaining the temperature at 80 ° C., a solution in which 67.5 g of 2-ethylhexyl acrylate, 18.0 g of vinyl acetate, 4.5 g of acrylic acid, and 0.3 g of lauroyl peroxide were dropped over 2.5 hours. Then, after completion of the dropwise addition, the reaction was further continued for 4 hours to obtain a solution of acrylic resin A-1 (weight average molecular weight 450,000) (solid content concentration 50 mass%).
The weight average molecular weight is measured using gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent, and converted using a standard polystyrene calibration curve using the following apparatus and measurement conditions. Is a value determined by In preparing the calibration curve, 5 sample sets (PStQuick MP-H, PStQuick B [trade name, “PStQuick” is a registered trademark]) were used as standard polystyrene.
Apparatus: RI detector L-3550 manufactured by Hitachi, Ltd.
Solvent: Tetrahydrofuran (THF)
Column: Hitachi Chemical Co., Ltd. Gelpac GL-R420 + GL-R430 + GL-R440
Column temperature: 40 ° C
Flow rate: 2 mL / min

Synthesis of Acrylic Polymer (A-2) Using 2-hydroxyethyl methacrylate instead of acrylic acid, synthesis was performed in the same manner as Acrylic Polymer A-1, and acrylic resin A-2 (weight average molecular weight 430,000) Solution (solid content concentration 50 mass%) was obtained.

(B) Component: Cross-linking agent containing (meth) acryloyl group Pentaerythritol triacrylate (Kyoeisha Chemical Co., Ltd. light acrylate PE-3A)
Component (C): Hydrogen abstraction type photoinitiator 4-Methylbenzophenone (SB-PI712 manufactured by Sojyo Sangyo Co., Ltd.)
(D) component: UV absorber Adekastab LA-32 (2- (2-hydroxy-5-methylphenyl) benzotriazole) manufactured by ADEKA Corporation

<Example 1>
[Preparation of adhesive layer]
Using polyethylene terephthalate (made by Fujimori Kogyo Co., Ltd.) having a thickness of 75 μm as the heavy release separator 4 and polyethylene terephthalate (made by Fujimori Kogyo Co., Ltd.) having a thickness of 50 μm as the temporary separator 6, the following (I) to (II) A pressure-sensitive adhesive sheet was prepared by the procedure described above.

  (I) Acrylic resin A-1 solution (solid content: 50 mass%) 200 g (100 g as acrylic resin A-1), pentaerythritol triacrylate (PE-3A) 1.5 g, 4-methylbenzophenone 1.0 g, 1.0 g of an ultraviolet absorber (ADK STAB LA-32) and 34 g of methyl ethyl ketone were mixed with stirring to obtain a coating solution.

(II) After coating this coating solution on the heavy release separator 3 to form a coating film, it was dried with a dryer at 100 ° C. for 15 minutes. After cooling to room temperature (25 ° C.), a temporary separator 6 is laminated and irradiated with ultraviolet rays (7.0 × 10 ² mJ / cm ² ) from the side of the heavy release separator using an ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd.). In addition, the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer 2 sandwiched between the heavy release separator 3 and the temporary separator 6 was obtained by irradiating ultraviolet rays (7.0 × 10 ² mJ / cm ² ) from the temporary separator side. The adhesive layer 2 was coated by adjusting the thickness to 150 μm.

<Examples 2-3> and <Comparative Example 1>
In the same manner as in Example 1, the pressure-sensitive adhesive layers of Examples 2 to 3 and Comparative Example 1 were prepared according to the formulation in Table 1, and pressure-sensitive adhesive sheets were obtained.

<Comparative Example 2>
(Synthesis of polycarbonate urethane acrylate)
In a glass reaction vessel equipped with a thermometer, a stirrer and a reflux tube, 45.01 g of methyl ethyl ketone, 6.26 g of isophorone diisocyanate, polycarbonate diol (T-5852 (registered trademark), manufactured by Asahi Kasei Chemicals Corporation) 47.02 g, 4- 0.03 g of methoxyphenol and 0.02 g of dibutyltin dilaurate were charged and heated to 70 ° C. with stirring. After incubating at 70 ° C. for 3 hours, 1.63 g of 2-hydroxyethyl acrylate was added, and the mixture was further reacted by stirring for 3 hours. It was confirmed that the isocyanate group disappeared by measuring the infrared spectrum. At that time, the reaction was terminated to obtain polycarbonate urethane acrylate (weight average molecular weight: 50,000).
75 parts by mass of the polycarbonate urethane acrylate, 24 parts by mass of phenoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), photoinitiator (Irgacur 184 manufactured by BASF, “Irgacur” is a registered trademark) (Mass%) was prepared and coated on the heavy release separator 3 to form a coating film, and then dried with a dryer at 100 ° C. for 15 minutes. After cooling to room temperature, the temporary separator 6 was laminated | stacked and the adhesive sheet of the comparative example 2 was obtained. The thickness of the adhesive layer was adjusted to 150 μm and applied.

<Comparative Example 3>
Synthesis of acrylic polymer (A-3) 84.0 g of 2-ethylhexyl acrylate (EHA) as an initial monomer, 2-hydroxyethyl in a reaction vessel equipped with a cooling tube, a thermometer, a stirrer, a dropping funnel and a nitrogen introducing tube 36.0 g of acrylate (HEA) and 150.0 g of methyl ethyl ketone were taken and heated from room temperature (25 ° C.) to 70 ° C. for 15 minutes while replacing with nitrogen at an air volume of 100 ml / min.
Thereafter, while maintaining this temperature, 21.0 g of 2-ethylhexyl acrylate and 9.0 g of 2-hydroxyethyl acrylate were used as additional monomers, and a solution in which 1.0 g of lauroyl peroxide was dissolved therein was prepared. Was added dropwise over 60 minutes, and the reaction was further continued for 2 hours after the completion of the dropwise addition.
Subsequently, methyl ethyl ketone was distilled off to obtain a copolymer of 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate (weight average molecular weight 150,000).

Synthesis of urethane acrylate (UA-1) In a reaction vessel equipped with a cooling tube, a thermometer, a stirrer, a dropping funnel and an air injection tube, 223.12 g of polypropylene glycol (molecular weight 2,000), 76.29 g of lactone-modified hydroxyethyl acrylate 99.68 g of 2-ethylhexyl acrylate, 0.12 g of p-methoxyphenol as a polymerization inhibitor and 0.5 g of dibutyltin dilaurate as a catalyst, heated to 75 ° C. while flowing air, and then stirred with 75 ° C. isophorone 49.35 g of diisocyanate was uniformly added dropwise over 2 hours to carry out the reaction.
When the reaction was allowed to proceed for 5 hours after completion of the dropwise addition, 44.85 g of 2-hydroxyethyl acrylate was further added and reacted for 1 hour. As a result of IR measurement, it was confirmed that the isocyanate had disappeared, and the reaction was terminated. Urethane acrylate UA-1 (weight average molecular weight) having polypropylene glycol and isophorone diisocyanate as repeating units and having a polymerizable unsaturated bond at both ends. 8,500) was obtained.

Preparation of pressure-sensitive adhesive sheet of Comparative Example 3 Acrylic polymer (A-3) 35 g, 2-ethylhexyl acrylate (EHA) 35.8 g, acryloylmorpholine (ACMO) 22 g, urethane acrylate UA-1 7 g, 1-hydroxycyclohexyl phenyl ketone ( Using 1 g of Irgacur 184), the mixture was stirred and mixed with the blending components and blending amounts shown in Table 1 to obtain an adhesive resin composition.
Then, the adhesive resin composition obtained above is dropped onto the heavy release separator (polyethylene terephthalate film) 3, and a temporary separator (polyethylene terephthalate film) is placed thereon, and the adhesive resin composition is covered with a roller. A transparent pressure-sensitive adhesive sheet was obtained by forming into a sheet shape and irradiating ultraviolet rays by 700 mJ / cm ^{2 on} each of the heavy release separator surface and the temporary separator surface using an ultraviolet irradiation device. The sheet thickness was set to 150 μm.

[Various evaluations]
The following (1) to (4) were evaluated for the pressure-sensitive adhesive sheets obtained in Examples 1 to 3 and Comparative Examples 1 to 3, and the results are shown in Table 1.

(1) Turbidity (haze)
The produced pressure-sensitive adhesive sheet was cut into dimensions of 40 mm in width and 100 mm in length, the polyethylene terephthalate film on one side of the pressure-sensitive adhesive sheet was peeled off, and a glass substrate having dimensions of 50 mm in width, 100 mm in length, and 0.5 mm in thickness (soda lime glass) ) Using a hand roller (25 ° C., load: 500 gf). 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 the haze of a transparent material).
Turbidity (haze) (%) = (Td / Tt) × 100
Td: scattered light (diffuse transmittance), Tt: total light transmittance

(2) Light transmittance The sample in which the turbidity was measured was measured using an ultraviolet-visible spectrophotometer (V-570 manufactured by JASCO Corporation), and the absorption spectrum in the range of 300 to 800 nm with the same glass substrate as the reference side. It was measured. Table 1 shows the light transmittance at 365 nm.

(3) Step embedding property and bonding reliability The prepared pressure-sensitive adhesive sheet was cut into dimensions of 50 mm in width and 80 mm in length, the polyethylene terephthalate film on one side of the pressure-sensitive adhesive sheet was peeled off, and the outer peripheral part was 9 mm in width and 40 μm in thickness. A glass substrate having a width of 56 mm, a length of 86 mm, and a thickness of 0.7 mm provided with a stepped portion having a size of 1 mm was bonded using a hand roller (25 ° C., load: 500 gf). Next, after peeling off the polyethylene terephthalate film on the other side to which the glass substrate provided with the step portion of the pressure-sensitive adhesive sheet is not bonded, the polarizing plate is applied to the glass substrate having dimensions of 56 mm in width, 86 mm in length, and 0.5 mm in thickness. On the polarizing plate surface of the substrate to which (Sumitomo Chemical Co., Ltd.) is attached, using a vacuum bonding apparatus (manufactured by Takatori Co., Ltd., trade name “TPL-0512MH”) at 25 ° C., 0.2 MPa, and a vacuum degree of 1000 Pa. Bonding was performed for 3 seconds under conditions. Then, the process by an autoclave (30 degreeC, 0.3 MPa) was performed for 10 minutes, and it was set as the evaluation sample. The step embedding property was evaluated based on the following criteria by measuring the shape and number of remaining bubbles. In addition to Example 2, after the autoclave treatment, an ultraviolet ray irradiation device (manufactured by Eye Graphics Co., Ltd.) was used to irradiate 2000 mJ / cm ² of ultraviolet rays from the side of the glass substrate provided with the stepped portion. did.
Next, the evaluation sample was heated in an oven at 100 ° C. for 30 minutes, the number of bubbles generated was measured, and the bonding reliability was evaluated according to the following criteria.
Evaluation criteria for step embedding A: No remaining bubbles B: 10 or less bubbles with a diameter of 1 mm or less C: Linear bubbles with a length of 1 cm or more remain D: Linear bubbles with a length of 3 cm or more remain Bonding reliability Evaluation criteria A: No generation of bubbles B: Generation of 10 bubbles or less having a diameter of 1 mm or less C: Generation of linear bubbles having a length of 5 mm or more D: External dimension of the adhesive layer changes

(4) Removability of pressure-sensitive adhesive The prepared pressure-sensitive adhesive sheet was cut into a size of 10 mm in width and 30 mm in length, the polyethylene terephthalate film on one side of the pressure-sensitive adhesive sheet was peeled off, and a step having a size of 9 mm in width and 40 μm in thickness on the outer periphery. A glass substrate having a width of 56 mm, a length of 86 mm, and a thickness of 0.7 mm was bonded to each other using a hand roller (25 ° C., load: 500 gf) so that the pressure-sensitive adhesive sheet was applied to the stepped portion. After leaving at room temperature for 1 hour, the polyethylene terephthalate film on the other side to which the glass substrate provided with the step portion of the pressure-sensitive adhesive sheet was not bonded was peeled off. The edge part of the adhesive sheet was pinched with a finger and peeled off from the glass substrate, and the adhesive removal property was evaluated according to the following criteria.
Evaluation criteria for pressure-sensitive adhesive removal A: The pressure-sensitive adhesive can be removed from the glass substrate by being peeled once. B: The pressure-sensitive adhesive can be removed from the glass substrate by being peeled within 3 times. C: After being peeled 3 times, the pressure-sensitive adhesive is removed. There is a remaining medicine

  As shown in Table 1, Examples 1 to 3 of the present invention having the components (A) to (D) are excellent in step embedding property and reliability, and easy to remove the adhesive, and excellent in reworkability. On the other hand, when the ultraviolet absorber of the component (D) of Comparative Example 1 is not included, the step embedding property and the reliability are inferior. Further, even when the hydrogen abstraction type photoinitiator (C) component of Comparative Examples 2 and 3 and the component (D) were not included, the step embedding property and the reliability were inferior, and in Comparative Example 3, it was difficult to remove the adhesive. .

  According to the present invention, it has excellent transparency, handleability, step embedding in a high step, and surface flatness, and a refractive index that correlates with a dielectric constant with an appropriate dielectric constant is close to that of an adherent, and is light transmissive. It is possible to provide an adhesive sheet for an image display device, which is provided with an adhesive layer that is improved in visibility and excellent in visibility. 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 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 1 ... Adhesive sheet, 2 ... Adhesive layer, 2a, 3a, 4a, 5a ... Outer edge, 2b, 2c ... Adhesive surface, 3 ... Heavy release separator (2nd base material layer), 3b, 5b ... Adhesive layer side surface 3 ..., 5c ... notches, 4 ... light release separator (first substrate layer), 5 ... carrier film (carrier layer), 6 ... temporary separator, 7 ... image display unit, 10 ... base material film, 12 DESCRIPTION OF SYMBOLS ... Liquid crystal display cell, 20, 22 ... Polarizing plate, 30 ... Touch panel, 31, 32 ... Transparent resin layer, 40 ... Transparent protective plate (glass or plastic substrate), 50 ... Backlight system, 60 ... Step part, 100 ... Oji Tools, A1, A2 ... adherend, B ... blade.

Claims (11)

  (A) Acrylic polymer, (B) Crosslinking agent having (meth) acryloyl group, (C) Photoinitiator, (D) At least one adhesive layer containing an ultraviolet absorber, and containing an ultraviolet absorber The adhesive sheet for image display apparatuses whose quantity is 0.05 to 5 mass% with respect to the total mass of an adhesive resin composition (adhesion layer).   The pressure-sensitive adhesive sheet for an image display device according to claim 1, wherein the pressure-sensitive adhesive layer is a single layer.   The pressure-sensitive adhesive sheet for an image display device according to claim 1 or 2, wherein the light transmittance at 365 nm of the pressure-sensitive adhesive layer is 10% or less with respect to the thickness of the pressure-sensitive adhesive layer used.   The acrylic polymer (A) of the adhesive layer contains an alkyl acrylate having 1 to 18 carbon atoms in the alkyl group and vinyl acetate as a copolymerization component. The adhesive sheet for an image display device according to any one of the above. The pressure-sensitive adhesive sheet for an image display device according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 10 μm to 2.0 × 10 ² μm.   The pressure-sensitive adhesive sheet for an image display device according to claim 1, further comprising first and second base material layers laminated so as to sandwich the pressure-sensitive adhesive layer. A carrier layer further laminated on the second base material layer;
The pressure-sensitive adhesive sheet for an image display device according to claim 6, wherein outer edges of the first base material layer and the carrier layer project outward from an outer edge of the pressure-sensitive adhesive layer.   The manufacturing method of the adhesive sheet for image display apparatuses as described in any one of Claims 1-7 provided with the process of irradiating an ultraviolet-ray after processing an adhesive resin composition into a sheet form. The process of sticking together adherends and obtaining a layered product through the adhesion layer with which the adhesive sheet for image display devices according to any one of claims 1 to 7 is provided,
A method for manufacturing an image display device, comprising: heating and pressurizing the laminate under conditions of 20 ° C. to 80 ° C. and 0.1 MPa to 0.6 MPa.   The method for manufacturing an 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, a transparent protective plate with a touch panel function, and a liquid crystal display cell. An image display unit;
A transparent protective plate,
The pressure-sensitive adhesive layer or the transparent resin layer, which is a cured product thereof, provided in the pressure-sensitive adhesive sheet for an image display device according to any one of claims 1 to 7, interposed between the image display unit and the transparent protective plate, An image display device comprising:

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