JP6056641B2 - Adhesive sheet for image display device, method for manufacturing image display device, and image display device - Google Patents

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 D7 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

  However, the film-like pressure-sensitive adhesive D9 as described in Patent Document 2 and Patent Document 3 shows that the step embedding property is not sufficient when the step generated by the decorative portion D7 is high. It became clear as a result of examination. Particularly recently, the thickness of the film-like pressure-sensitive adhesive has been reduced, and if a thin film-like pressure-sensitive adhesive is used for the adherend having a high level difference, it becomes more difficult to sufficiently fill the level difference. There is a tendency. In addition, the film-like pressure-sensitive adhesive also needs to have high adhesion to the adherend so that visibility is not lowered due to peeling of the pressure-sensitive adhesive and the adherend.

  The present invention has been made in view of the above circumstances, and provides a pressure-sensitive adhesive layer that is excellent in embedding into a step and excellent in adhesion and visibility even when the step formed on the adherend is high. It aims at providing the adhesive sheet for image display apparatuses provided. Another object of the present invention is to provide an image display device manufacturing method and an image display device using the pressure-sensitive adhesive sheet for the image display device.

  As a result of intensive studies by the present inventors, it has a pressure-sensitive adhesive layer comprising a polycarbonate urethane having no (meth) acryloyl group, a compound having an ethylenically unsaturated bond, a phenoxy resin and a photopolymerization initiator, and the haze of the pressure-sensitive adhesive layer. It has been found that the above-mentioned problems can be solved if the pressure-sensitive adhesive sheet for image display device is 1.5% or less. The present invention has been completed based on such findings.

  That is, the present invention includes a pressure-sensitive adhesive layer containing a polycarbonate urethane having no (meth) acryloyl group, a compound having an ethylenically unsaturated bond, a phenoxy resin, and a photopolymerization initiator, and the haze of the pressure-sensitive adhesive layer is 1.5. % Or less of the pressure-sensitive adhesive sheet for an image display device.

  Such a pressure-sensitive adhesive sheet for an image display device (hereinafter sometimes simply referred to as “pressure-sensitive adhesive sheet”) is excellent in embedding in a step formed on an adherend, and has excellent adhesiveness and visibility. Also excellent.

  The thickness of the adhesive layer in the adhesive sheet which concerns on one Embodiment of this invention can be 50-200 micrometers. Thereby, the pressure-sensitive adhesive sheet is more excellent in impact resistance and visibility.

  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.

  The present invention also includes a step of bonding the adherends together to obtain a laminate through the adhesive layer provided in the adhesive sheet, and heating the laminate under conditions of 40 to 80 ° C. and 0.1 to 0.6 MPa. And the manufacturing method of an image display apparatus provided with the process of pressurizing, and the process of irradiating an ultraviolet-ray with respect to the adhesion layer in the said laminated body is provided.

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

  The present invention is also the image display unit, the transparent protective plate, the adhesive layer or the cured product thereof provided in the pressure-sensitive 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. An image display device comprising a certain transparent resin layer is provided.

  Moreover, this invention is the said adhesive layer with which the adhesive sheet for image displays which concerns on the said this invention which interposes between an image display unit, a touch panel, a transparent protective plate, and a touch panel and a transparent protective plate, or its hardening | curing. An image display device comprising a transparent resin layer, which is a product, is provided.

  The present invention also provides an image display device in which 0.4 <(h / t) <1 when the height of the step is h and the thickness of the transparent resin layer is t. At this time, the thickness t of the transparent resin layer is the thickness of the adhesive layer interposed between the adherends not considering the height of the step, and is usually the same as the distance between the adherends.

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

  The 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, there is provided a pressure-sensitive adhesive sheet for an image display device comprising a pressure-sensitive adhesive layer that has excellent step embedding properties and excellent adhesion and visibility even when the level difference formed on an adherend is high. be able to. According to the present invention, it is also possible to provide an adhesive sheet for an image display device in which bleeding is suppressed. 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. It is a schematic diagram which shows the sample for evaluation of level | step difference embedding property.

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

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

  That is, as shown in 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 protrude beyond the outer edge of the adhesive layer 2. This adhesive layer 2 is, for example, a transparent film (transparent resin) disposed between a transparent protective plate and a touch panel or between a touch panel and a liquid crystal display unit in an image display device such as a touch panel display for a portable terminal. Layer).

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

  The haze of the pressure-sensitive adhesive layer 2 depends on the compatibility of the components (A), (B) and (C) described later. If the compatibility between the components (A), (B) and (C) 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.

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

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

  The adhesive layer 2 contains a polycarbonate urethane having no (meth) acryloyl group, a compound having an ethylenically unsaturated bond, a phenoxy resin, and a photopolymerization initiator. According to such a pressure-sensitive adhesive layer 2, it has excellent adhesiveness and excellent step embedding property even when the step is high.

  The pressure-sensitive adhesive layer 2 includes, for example, a pressure-sensitive resin composition containing polycarbonate urethane not having a (meth) acryloyl group, a compound having an ethylenically unsaturated bond, a phenoxy resin, and a photopolymerization initiator on the heavy release separator 3. It is formed by coating with an arbitrary thickness.

  Hereinafter, the adhesive resin composition will be described.

[Component (A): Polycarbonate urethane not having a (meth) acryloyl group]
The polycarbonate urethane having no (meth) acryloyl group (hereinafter sometimes referred to as polycarbonate urethane) is not particularly limited as long as it has a carbonate bond and a urethane bond and does not have a (meth) acryloyl group. Examples of such a component (A) include polycarbonate urethane obtained by a reaction between a diisocyanate compound and a polycarbonate diol.

  Polycarbonate urethane has high crystallinity at room temperature, and crystallinity collapses at high temperatures and becomes amorphous. Therefore, when used in combination with the component (C) described later, surface tackiness is low at room temperature. High adhesion to the adherend can be achieved by pressure bonding at high temperatures. Polycarbonate urethane is also excellent in flexibility and water resistance. Therefore, there also exists an advantage that it is excellent in the handleability of the adhesive layer which is a film form. In addition, the inventors consider that the polycarbonate urethane is excellent in compatibility with the phenoxy resin, which is the component (C) described later, as a factor that enables high adhesion to the adherend.

As said diisocyanate compound, the compound represented by following General formula (1) is mentioned, for example.
OCN-X-NCO (1)
[In formula (1), X represents a divalent organic group. ]

  X in the general formula (1) is, for example, an alkylene group having 1 to 20 carbon atoms, an unsubstituted or phenylene group substituted with a lower alkyl group having 1 to 5 carbon atoms such as a methyl group. And arylene groups such as a naphthylene group. When X is an alkylene group, the alkylene group preferably has 1 to 18 carbon atoms. Other examples of X include a group having an aromatic ring such as phenylene group, xylylene group, naphthylene group, diphenylmethane-4,4′-diyl group, diphenylsulfone-4,4′-diyl group, and hydrogenation. Examples thereof include groups selected from groups having an alicyclic skeleton such as diphenylmethane-4,4′-diyl group and isophorone-diyl group.

  Examples of the diisocyanate compound represented by the general formula (1) include diphenylmethane-2,4′-diisocyanate; 3,2′-, 3,3′-, 4,2′-, 4,3′-, 5,2'-, 5,3'-, 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate; 3,2'-, 3,3'-, 4,2'- 4,3'-, 5,2'-, 5,3'-, 6,2'- or 6,3'-diethyldiphenylmethane-2,4'-diisocyanate; 3,2'-, 3,3 ' -, 4,2'-, 4,3'-, 5,2'-, 5,3'-, 6,2'- or 6,3'-dimethoxydiphenylmethane-2,4'-diisocyanate; diphenylmethane-4 , 4'-diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenyl Diphenylmethane diisocyanate compounds such as tan-3,4'-diisocyanate and hydrogenated products thereof; diphenyl ether-4,4'-diisocyanate, benzophenone-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, tolylene- 2,4-diisocyanate, tolylene-2,6-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, 1,5-naphthalene diisocyanate, [2,2-bis (4-phenoxyphenyl) propane] -4, Aromatic diisocyanates such as 4'-diisocyanate; hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-dii Cyanate, trans - cyclohexane-1,4-diisocyanate, hydrogenated m- xylylene diisocyanate, aliphatic or alicyclic diisocyanates such as lysine diisocyanate and the like. These can be used individually by 1 type or in combination of 2 or more types.

  Moreover, the diisocyanate compound represented by the general formula (1) may be stabilized with a blocking agent necessary for avoiding changes over time. Examples of the blocking agent include alcohols such as hydroxy acrylate and methanol, phenol, and oxime, but are not particularly limited.

  As said polycarbonate diol, the polycarbonate diol represented by following General formula (2) is mentioned, for example.

［式（２）中、Ｒは炭素数が１〜１８であるアルキレン基を示し、ｍは１〜３０の整数を示す。］

[In the formula (2), R represents an alkylene group having 1 to 18 carbon atoms, and m represents an integer of 1 to 30. ]

  Examples of the polycarbonate diol represented by the general formula (2) include α, ω-poly (hexamethylene carbonate) diol and α, ω-poly (3-methyl-pentamethylene carbonate) diol. Can also be used. Commercially available products include PLACEL CD-205, 205PL, 205HL, 210, 210PL, 210HL, 220, 220PL, 220HL (trade name) manufactured by Daicel Chemical Industries, Ltd., and PCDL T-5651, T manufactured by Asahi Kasei Chemicals Corporation. -5652, T-6001, T-6002, G-3452, PCDX-55 (trade name), UH-50, 100, 200, 300, UHC-50-100, UHC-50-200 manufactured by Ube Industries, Ltd. Is mentioned. These can be used individually by 1 type or in combination of 2 or more types.

  In addition, the polycarbonate diol represented by the above general formula (2) is replaced with a diol such as polybutadiene diol, polyisoprene diol, polycarbonate diol other than the above general formula (2), polyether diol, polyester diol, polycaprolactone diol, and silicone diol. May be used in combination.

  The blending ratio when the diisocyanate compound represented by the above general formula (1) and the polycarbonate diol represented by the above general formula (2) are reacted is the weight average molecular weight of the produced polycarbonate urethane and the terminal of the polycarbonate urethane. It is appropriately adjusted depending on whether is made a hydroxyl group or an isocyanate group.

  In order to obtain a polycarbonate urethane having a hydroxyl group at the terminal, the blending ratio is adjusted so that the ratio between the number of hydroxyl groups of the polycarbonate diol and the number of isocyanate groups of the diisocyanate compound (number of hydroxyl groups / isocyanate groups) is 1.01 or more. It is preferable to adjust to 2 or less from the viewpoint of reaction efficiency.

  In the case of a polycarbonate urethane having a hydroxyl group at the terminal, the terminal of the polycarbonate urethane is reacted by reacting the terminal hydroxyl group with a compound capable of reacting with a hydroxyl group such as monocarboxylic acids such as acetic acid and propionic acid, and acid anhydrides. It may be further modified.

  On the other hand, in order to obtain a polycarbonate urethane having an isocyanate group at the terminal, the ratio of the number of isocyanate groups in the diisocyanate compound to the number of hydroxyl groups in the diol compound (the number of isocyanate groups / the number of hydroxyl groups) is adjusted to 1.01 or more. It is preferable to adjust the weight average molecular weight to 1.9 or less from the viewpoint of increasing the weight average molecular weight. By setting it as such a ratio, it becomes polycarbonate urethane which has an isocyanate group at the terminal. The polycarbonate urethane having an isocyanate group at the terminal is, for example, a compound capable of reacting with an isocyanate group such as a monohydroxy compound such as methanol or ethanol, a lactam, an oxime, a monocarboxylic acid, or a divalent acid anhydride. The terminal of the polycarbonate urethane may be further modified by reacting with the isocyanate group at the terminal of the polycarbonate urethane having an isocyanate group at the terminal.

  5000-100000 may be sufficient as the weight average molecular weight of the polycarbonate urethane which does not have a (meth) acryloyl group which is (A) component. When the weight average molecular weight is 5000 or more, the step embedding property tends to be further improved, and when it is 100000 or less, the tackiness tends to be maintained. Similarly, from the viewpoint of step embedding and adhesiveness, the weight average molecular weight is preferably 10,000 to 80,000, more preferably 10,000 to 60,000, and still more preferably 10,000 to 30,000. The measurement conditions for the weight average molecular weight are the same as those in the examples of the present specification.

  The content of the polycarbonate urethane having no (meth) acryloyl group as the component (A) is 20 to 85 parts by mass, 30 to 30 parts by mass with respect to 100 parts by mass of the total amount of the components (A), (B) and (C). 75 mass parts or 40-60 mass parts may be sufficient. When the content is within these ranges, the effects of step embedding into a high step and adhesiveness can be obtained more remarkably.

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

  Specific examples of the component (B) include, for example, alkylene diol di (meth) acrylate having 6 to 18 carbon atoms, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyester (meth) acrylate, Urethane (meth) acrylate, epoxy acrylate (resin obtained by reacting epoxy resin with (meth) acrylic acid), trimethylolpropane tri (meth) acrylate, tetramethylol methane tri (meth) acrylate, tetramethylol methane tetra (meth) ) Acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like. Among these, urethane (meth) acrylate or epoxy acrylate is preferable from the viewpoint of improving compatibility with the component (A) and the component (C) and further reducing haze.

  The urethane (meth) acrylate can be obtained, for example, as follows. First, a diisocyanate compound and a diol compound are reacted to prepare a urethane compound having a hydroxyl group at the terminal or a urethane compound having an isocyanate group at the terminal. Whether the terminal is a hydroxyl group or an isocyanate group can be adjusted by the blending ratio of the diisocyanate compound and the diol compound as described above.

  In the case of the urethane compound having a hydroxyl group at the terminal, for example, urethane di (meth) acrylate can be obtained by reacting acrylic acid or 2-isocyanatoethyl (meth) acrylate. When a urethane compound having an isocyanate group at the terminal is used, urethane di (meth) acrylate can be obtained by reacting a monohydroxy compound having an ethylenically unsaturated bond.

  As said diisocyanate compound and a diol compound, the thing similar to the compound illustrated by (A) component is mentioned.

  Examples of the monohydroxy compound having an ethylenically unsaturated bond include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 1,4-cyclohexane. Dimethanol mono (meth) acrylate, caprolactone or polyoxyalkylene adduct of each of the above (meth) acrylates, glycerin di (meth) acrylate, trimethylol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (Meth) acrylate, ditrimethylolpropane tri (meth) acrylate, allyl alcohol, 2-allyloxyethanol and the like can be mentioned.

  The component (B) is preferably a compound using the polycarbonate diol represented by the general formula (2) as the diol compound from the viewpoint of further improving the compatibility with the component (A). The polycarbonate urethane (meth) acrylate represented by 3) is more preferable.

［式（３）中、Ｒは、炭素数が１〜１８であるアルキレン基を示し、Ｒ^２は水素原子又はメチル基を示し、Ｘは２価の有機基を示し、Ｚは２〜６価の有機基を示す。ｍ及びｎはそれぞれ独立に１〜３０の整数を示し、ｐ及びｑはそれぞれ独立に１〜５の整数を示す。複数存在するＲ、Ｒ^２、Ｘ及びＺはそれぞれ同一でも異なっていてもよい。ｎが２以上の場合、複数存在するｍはそれぞれ同一でも異なっていてもよい。］

[In the formula (3), R represents an alkylene group having 1 to 18 carbon atoms, R ² represents a hydrogen atom or a methyl group, X represents a divalent organic group, and Z represents 2 to 6 valences. An organic group of m and n each independently represents an integer of 1 to 30, and p and q each independently represents an integer of 1 to 5. A plurality of R, R ² , X and Z may be the same or different. When n is 2 or more, a plurality of m may be the same or different. ]

  The polycarbonate urethane (meth) acrylate represented by the general formula (3) includes a diisocyanate compound represented by the following general formula (4), 2-hydroxyethyl (meth) acrylate, pentaerythritol tri (meth) acrylate, and di It can be obtained by reacting a compound having a (meth) acryloyl group and a hydroxyl group such as pentaerythritol penta (meth) acrylate.

［式（４）中、Ｒは炭素数が１〜１８であるアルキレン基を示し、Ｘは２価の有機基を示す。ｍ及びｎはそれぞれ独立に１〜３０の整数を示す。複数存在するＲ及びＸはそれぞれ同一でも異なっていてもよい。ｎが２以上の場合、複数存在するｍはそれぞれ同一でも異なっていてもよい。］

[In the formula (4), R represents an alkylene group having 1 to 18 carbon atoms, and X represents a divalent organic group. m and n each independently represents an integer of 1 to 30. A plurality of R and X may be the same or different. When n is 2 or more, a plurality of m may be the same or different. ]

  Among these components (B), in particular, from the viewpoint of improving both the adhesiveness and the adhesiveness after irradiation with active energy rays and the reliability under high temperature and high humidity (reduction of generation of bubbles and suppression of peeling), ethylene of 2 or less A polycarbonate (meth) acrylate having a polymerizable unsaturated bond can be used. As the polycarbonate (meth) acrylate having 2 or less ethylenically unsaturated bonds, the polycarbonate represented by the following general formula (5) in which both p and q are 1 in the compound represented by the above general formula (3) A urethane (meth) acrylate is mentioned. When polycarbonate (meth) acrylate is used as the component (B), compatibility with the component (A) and the component (C) can be improved, and haze tends to be further reduced.

［式（５）中、Ｒは、炭素数が１〜１８であるアルキレン基を示し、Ｒ^２は、水素原子又はメチル基を示し、Ｘ及びＺは、それぞれ独立に２価の有機基を示す。ｍ及びｎはそれぞれ独立に１〜３０の整数を示す。複数存在するＲ、Ｒ^２、Ｘ及びＺはそれぞれ同一でも異なっていてもよい。ｎが２以上の場合、複数存在するｍはそれぞれ同一でも異なっていてもよい。］

[In the formula (5), R represents an alkylene group having 1 to 18 carbon atoms, R ² represents a hydrogen atom or a methyl group, and X and Z each independently represent a divalent organic group. . m and n each independently represents an integer of 1 to 30. A plurality of R, R ² , X and Z may be the same or different. When n is 2 or more, a plurality of m may be the same or different. ]

  The polycarbonate (meth) acrylate may have a weight average molecular weight of 5,000 to 100,000. When the weight average molecular weight is 5,000 or more, bleeding of the adhesive layer tends to be suppressed, and when it is 100,000 or less, the step embedding property tends to be maintained. Similarly, the weight average molecular weight may be 10,000 to 80,000 or 20,000 to 60,000 from the viewpoints of suppression of bleeding and step embedding. The measurement conditions for the weight average molecular weight are the same as those in the examples of the present specification. Moreover, when the weight average molecular weight of (A) component is 20000-50000, there exists a tendency for adhesiveness to improve further that the weight average molecular weight of polycarbonate (meth) acrylate is 50000-80000.

  The epoxy acrylate can be obtained, for example, by reacting an epoxy resin with a vinyl group-containing monocarboxylic acid. Examples of the epoxy resin include novolak type epoxy resins, bisphenol A type epoxy resins represented by the following general formula (6) (hereinafter referred to as bisphenol A type phenoxy resins) or bisphenol F type epoxy resins (hereinafter referred to as bisphenol F type phenoxy resins). ) And the like.

［式中、Ｒ^１２は水素原子又はメチル基を示し、Ｙ^２は水素原子又はグリシジル基を示し、ｎ２は１以上の整数を示す。なお、複数存在するＲ^１２及びＹ^２はそれぞれ同一でも異なっていてもよい。］

[Wherein, R ¹² represents a hydrogen atom or a methyl group, Y ² represents a hydrogen atom or a glycidyl group, and n2 represents an integer of 1 or more. A plurality of R ¹² and Y ² may be the same or different. ]

Further, in the compound represented by the general formula (6), the bisphenol A type phenoxy resin or bisphenol F type phenoxy resin in which Y ² is a glycidyl group is, for example, a bisphenol A type phenoxy resin represented by the following general formula (7). Or it can obtain by making the hydroxyl group of bisphenol F type phenoxy resin react with epichlorohydrin.

［式中、Ｒ^１２は水素原子又はメチル基を示し、ｎ２は１以上の整数を示す。なお、複数存在するＲ^１２はそれぞれ同一でも異なっていてもよい。］

[Wherein, R ¹² represents a hydrogen atom or a methyl group, and n2 represents an integer of 1 or more. A plurality of R ¹² may be the same or different. ]

  In order to promote the reaction between the hydroxyl group and epichlorohydrin, polar organic solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide in the presence of alkali metal hydroxide at a reaction temperature of 50 to 120 ° C. It is preferable to carry out the reaction in the medium.

  Examples of the vinyl group-containing monocarboxylic acid include (meth) acrylic acid, dimer of (meth) acrylic acid, β-furfuryl (meth) acrylic acid, β-styryl (meth) acrylic acid, cinnamic acid, and croton. Examples include acids and α-cyanocinnamic acid.

  From the viewpoint of further improving the compatibility with the components (A) and (C), the bisphenol A type phenoxy resin or bisphenol F type phenoxy resin represented by the general formula (6) is reacted with (meth) acrylic acid. The bisphenol type epoxy acrylate obtained by making this into is preferable. There is a tendency that compatibility with the components (A) and (C) can be improved and haze can be further reduced.

  The epoxy acrylate may have a weight average molecular weight of 500 to 100,000. When the weight average molecular weight is 500 or more, the adhesiveness tends to be further improved and bleeding of the pressure-sensitive adhesive layer tends to be suppressed. When the weight average molecular weight is 100000 or less, the step burying property to a high step can be maintained. It tends to be possible. Similarly, the weight average molecular weight may be 800 to 80,000 or 900 to 60000 from the viewpoints of adhesiveness, seepage suppression, and step embedding. The measurement conditions for the weight average molecular weight are the same as those in the examples of the present specification.

  (B) Content of the compound which has an ethylenically unsaturated bond which is a component is 5-70 mass parts, 10-55 mass with respect to 100 mass parts of total amounts of (A), (B) and (C) component. Part or 20 to 40 parts by mass. When the content is within these ranges, the effect of excellent step embedding into a high step and excellent adhesion can be obtained more remarkably.

[(C) component: phenoxy resin]
By using a phenoxy resin as the component (C), the adhesiveness can be further improved. The phenoxy resin can be generally produced by a one-step method in which a bisphenol and epichlorohydrin are polycondensed or by a two-step method in which a bifunctional epoxy resin and a bisphenol are polyaddition-reacted.

  Examples of phenoxy resins include bisphenol A type phenoxy resin, bisphenol F type phenoxy resin, bisphenol A / bisphenol F copolymer type phenoxy resin, bisphenol S type phenoxy resin, brominated phenoxy resin, phosphorus-containing phenoxy resin, and fluorene skeleton. And phenoxy resin. These can be used alone or in combination of two or more.

The phenoxy resin is more preferably a bisphenol A type phenoxy resin in which R ¹² in the general formula (7) is a methyl group from the viewpoint of further improving the light-shielding part curability described later.

  The weight average molecular weight of the phenoxy resin is preferably 10,000 to 100,000, more preferably 20,000 to 80,000, and more preferably 30,000 to 70,000 from the viewpoints of adhesiveness and compatibility with the components (A) and (B). More preferably it is. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) and converted to standard polystyrene.

  A commercially available product can be used as the phenoxy resin. Commercially available products include, for example, Phenototo YP-50, Phenototo YP-50S, Phenototo YP-55, Phenototo YP-70 or FX280 (both are trademarks) manufactured by Toto Kasei Co., Ltd., Japan Epoxy Resin Co., Ltd. Examples thereof include JER1256, JER4250 or JER4275 (all are trademarks), PKHB, PKHC, PKHH, PKHJ, PKFE, PKHP-200, PKHP-80, PKHB-100 or PKHB-300 (all are trademarks) manufactured by InChem.

  The content of the phenoxy resin may be 10 to 75 parts by mass, 15 to 60 parts by mass or 20 to 40 parts by mass with respect to 100 parts by mass of the total amount of the components (A), (B) and (C). . When the content is within these ranges, the effect of excellent adhesion can be obtained more remarkably.

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

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

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

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

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

  The content of the component (D) is 0.05 to 5% by mass, 0.1 to 3% by mass, or 0.1 to 2% by mass with respect to the total mass of the adhesive resin composition (adhesive layer). May be. By setting the content of the component (D) to 5% by mass or less, it is possible to obtain an adhesive layer having higher light transmittance, a hue that is not yellowish, and excellent in step embedding. . When the content of the component (D) is within these ranges, the effect of excellent adhesion and reliability under high temperature and high humidity can be obtained more remarkably.

Other components The adhesive resin composition may contain an acrylic monomer, various additives, and the like separately from the components (A), (B), (C), and (D) 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.

  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 may be 30 to 70 mass% or 40 to 60 mass%. The viscosity of the coating liquid may be 1 to 30 Pa · s, 5 to 25 Pa · s, or 5 to 15 Pa · s.

  The pressure-sensitive adhesive layer 2 includes a base material layer (heavy release separator 3) that is a polymer film such as a polyethylene terephthalate film (hereinafter sometimes referred to as “PET film”), and a base material that is a cover film of the same type of material. It may be sandwiched between layers (light release separator 4). 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 with the total content of the above components (A), (B), (C) and (D), and is generally the total mass of the adhesive resin composition. It is 0.01-5 mass% with respect to.

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

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

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

  The peel strength between the light release separator 4 and the adhesive layer 2 may be lower than the peel strength between the heavy release separator 3 and the adhesive layer 2. Thereby, the heavy release separator 3 is less likely to peel from the adhesive layer 2 than the light release separator 4. As will be described later, when the blade B is passed through the pressure-sensitive adhesive layer 2 toward the heavy release separator 3, the outer edge portion of the pressure-sensitive adhesive layer 2 is pressed against the heavy release separator 3. Thereby, the heavy release separator 3 becomes more difficult to peel from the adhesive layer 2 than the light release separator 4, and it becomes easier to release the light release separator 4 before the heavy release separator 3 is peeled off. Therefore, the heavy release separator 3 and the light release separator 4 can be peeled one by one, and the work of peeling the heavy release separator 3 and the light release separator 4 and sticking the adhesive layer 2 to separate adherends is ensured one by one. Can be done. The peel strength between the heavy release separator 3 and the pressure-sensitive adhesive layer 2 and between the light release separator 4 and the pressure-sensitive adhesive layer 2 can be adjusted, for example, by subjecting the heavy release separator 3 and the light release separator 4 to surface treatment. Examples of the surface treatment method include release treatment with a silicone compound or a fluorine compound.

<Method 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 acrylate and an epoxy acrylate; base films, such as a polyethylene film, can be used, for example. Similarly, in order to increase the surface hardness, 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 or a cured product thereof. The level difference due to the level difference portion 60 varies depending on the size of the liquid crystal display device, but when the height is 40 μm to 100 μm, particularly 60 to 100 μm, it is particularly useful to use the adhesive layer of this embodiment. When the height of the stepped portion 60 is in the above range, the adhesive layer 2 is preferably thicker from the viewpoint of the step embedding property, but the adhesive layer 2 of the present embodiment has a step embedding property even when the film thickness is small. Excellent. When the height of the step portion is h and the thickness of the transparent resin layer is t, excellent step embedding property is obtained even if 0.4 <(h / t) <1. Moreover, the pressure-sensitive adhesive layer 2 of the present embodiment exhibits excellent step embedding properties even when (h / t)> 0.5. From a practical viewpoint, (h / t) <0.9 may be satisfied.

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

  In the liquid crystal display device of FIG. 9, a transparent resin layer is interposed between the image display unit 7 and the touch panel 30 and between the touch panel 30 and the transparent protective plate 40. However, the transparent resin layer only needs to be interposed in at least one of these, and particularly when the adhesive layer 2 of the present embodiment is used as the transparent resin layer, the touch panel 30 and the transparent protective plate 40 forming a step are provided. It is preferable that a transparent resin layer is interposed therebetween. When the touch panel is on-cell, the touch panel and the liquid crystal display cell are integrated. As a specific example thereof, a liquid crystal display device in which the liquid crystal display cell 12 of the liquid crystal display device of FIG.

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

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

  As the liquid crystal display cell 12, a liquid crystal material that is well known in the art can be used. The liquid crystal display cell is classified into a TN (Twisted Nematic) method, a STN (Super-Twisted Nematic) method, a VA (Vertical Alignment) method, an IPS (In-Place-Switching) method, etc., depending on the control method of the liquid crystal material. The liquid crystal display device according to the present embodiment may be a liquid crystal display cell using any control method.

  As the polarizing plates 20 and 22, a polarizing plate common in this technical field can be used. Treatments such as antireflection, antifouling, and hard coating may be performed on one or both surfaces of the polarizing plates.

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

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

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

  As the transparent protective plate 40, a general optical transparent substrate can be used. Specific examples thereof include inorganic 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 A2 with a roller R or the like. At this time, the step formed by the stepped portion 60 on the surface of the adherend A1 is buried by the flow of the adhesive layer 2. When the pressure-sensitive adhesive layer 2 is pressed against the adherend A2, the pressure-sensitive adhesive layer 2 may be heated to 40 to 80 ° C., for example. By heating the pressure-sensitive adhesive layer 2 to 40 to 80 ° C., the pressure-sensitive adhesive layer 2 becomes easier to flow, and the effect that the step embedding property in the stepped portion 60 is excellent can be obtained more remarkably. This temperature may be 50 to 70 ° C. because the bubbles near the step can be more efficiently removed. The adherend A1 is, for example, an image display unit, a transparent protective plate, or a touch panel.

  Subsequently, as shown in FIG. 12, the heavy release separator 3 is peeled from the adhesive layer 2 to expose the adhesive surface 2 c of the adhesive layer 2. Subsequently, as shown in FIG. 13, the pressure-sensitive adhesive surface 2 c of the pressure-sensitive adhesive layer 2 is attached to the adherend A <b> 2, and the obtained laminate is heated and pressurized (for example, treatment by autoclave). The adherend A2 is, for example, an image display unit, a transparent protective plate, or a touch panel. In this way, the adherends can be bonded together via the adhesive layer 2. Conditions for heating and pressurizing the laminate are, for example, a temperature of 40 to 80 ° C. and a pressure of 0.1 to 0.6 MPa. When the step on the surface of the adherend is 40 to 100 μm, air bubbles in the vicinity of the step can be more efficiently removed, so the temperature may be 50 to 70 ° C. and the pressure may be 0.2 to 0.5 MPa. . The time of heating and pressurization may be 5 to 60 minutes, or 10 to 50 minutes.

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

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

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

  Further, from the viewpoint of more uniformly curing the adhesive resin composition existing in the region of the adhesive layer 2 (light-shielding part curability), the component (C) preferably uses a bisphenol A type phenoxy resin. When the component (C) is a bisphenol A type phenoxy resin, the light transmittance is high, the active energy rays easily reach the inside of the adhesive layer, the adhesive layer 2 can be cured more uniformly, and the light-curing part curability is improved. It tends to be higher.

Although the irradiation amount in particular of an ultraviolet-ray is not restrict | limited, 500-5000mJ / cm < ² > may be sufficient. The step of irradiating with ultraviolet rays can be performed after heating and pressurization of the laminate from the viewpoint of improving reliability under high temperature and high humidity.

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

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

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

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

[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 projects outward from the outer edge 2 a of the adhesive layer 2. Thereby, the carrier film 5 can be easily peeled from the heavy release separator 3 by pinching the outer edge portion of the carrier film 5 protruding outward. The outer edge 5 a of the carrier film 5 projects outward from the outer edge 4 a of the light release separator 4. Thereby, since the outer edge part of the carrier film 5 becomes easier to pinch, the carrier film 5 can be peeled off more easily. The width of the portion of the carrier film 5 that protrudes from the outer edge 4a of the light release separator 4 is 0.5 to 10 mm or 1 to 5 mm from the viewpoint of ease of handling, ease of peeling, and adhesion of dust and the like. There may be. When the planar shape of the carrier film 5, the adhesive layer 2, the heavy release separator 3 and the light release separator 4 is a substantially rectangular shape such as a substantially rectangular shape, the portion of the carrier film 5 that protrudes from the outer edge 4 a of the light release separator 4. The width may be 0.5-10 mm or 1-5 mm on at least one side, or 0.5-10 mm or 1-5 mm on all sides.

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

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

  The peel strength between the light release separator 4 and the adhesive layer 2 is lower than the peel strength between the heavy release separator 3 and the adhesive layer 2. The peel strength between the carrier film 5 and the heavy release separator 3 is lower than the peel strength between the heavy release separator 3 and the adhesive layer 2. Here, the peel strength between the carrier film 5 and the heavy release separator 3 is preferably lower than the peel strength between the light release separator 4 and the pressure-sensitive adhesive layer 2, but may be high.

  The peel strength between the carrier film 5 and the heavy release separator 3 may be adjusted 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 to 10 μm or 1 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 portions of the temporary separator 6 and the pressure-sensitive adhesive layer 2 are removed, and the outer portion of the heavy release separator 3 is left on the carrier film 5 without being removed. It may be in the state. Thereby, it can prevent effectively that the carrier film 5 by which surface exposure was carried out adheres to another part.

  After removing the outer portions of the temporary separator 6, the adhesive layer 2 and the heavy release separator 3 as shown in FIG. 18, the temporary separator 6 is subsequently released from the adhesive layer 2 as shown in FIG. A light release separator 4 is affixed to the adhesive layer 2 as shown. The pressure-sensitive adhesive sheet 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 in more detail 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 polycarbonate urethane 1)
In a glass reaction vessel equipped with a thermometer, a stirrer, and a reflux tube, 45.01 parts by mass of methyl ethyl ketone, 6.98 parts by mass of isophorone diisocyanate, polycarbonate diol (T-5652 (registered trademark), manufactured by Asahi Kasei Chemicals Corporation) 47.21 parts by mass, p-methoxyphenol 0.03 parts by mass and dibutyltin dilaurate 0.02 parts by mass were added and heated to 70 ° C. with stirring. After stirring at 70 ° C. for 3 hours, 0.75 part by mass of methanol was added, and the mixture was further stirred for 3 hours to be reacted. It was confirmed that the isocyanate group disappeared by measuring the infrared spectrum. At that time, the reaction was terminated to obtain polycarbonate urethane (weight average molecular weight 20000).

(Synthesis of polycarbonate urethane 2)
In a glass reaction vessel equipped with a thermometer, a stirrer and a reflux tube, 45.01 parts by mass of methyl ethyl ketone, 6.41 parts by mass of isophorone diisocyanate, polycarbonate diol (T-5652 (registered trademark), manufactured by Asahi Kasei Chemicals Corporation) 48.13 parts by mass, 0.03 parts by mass of p-methoxyphenol and 0.02 parts by mass of dibutyltin dilaurate were added and heated to 70 ° C. with stirring. After stirring at 70 ° C. for 3 hours, 0.46 part by mass of methanol was added, and the mixture was further stirred for 3 hours to be reacted. It was confirmed that the isocyanate group disappeared by measuring the infrared spectrum. At that time, the reaction was terminated to obtain polycarbonate urethane (weight average molecular weight 50000).

(Synthesis of polycarbonate urethane 3)
In a glass reaction vessel equipped with a thermometer, a stirrer and a reflux tube, 45.01 parts by mass of methyl ethyl ketone, 5.96 parts by mass of isophorone diisocyanate, polycarbonate diol (T-5652 (registered trademark), manufactured by Asahi Kasei Chemicals Corporation) 48.73 parts by mass, 0.03 parts by mass of p-methoxyphenol and 0.02 parts by mass of dibutyltin dilaurate were added and heated to 70 ° C. with stirring. After stirring at 70 ° C. for 3 hours, 0.23 part by mass of methanol 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 (weight average molecular weight 80000).

Component (B) (Synthesis of polycarbonate urethane acrylate 1)
In a glass reaction vessel equipped with a thermometer, a stirrer and a reflux tube, 45.01 parts by mass of methyl ethyl ketone, 6.74 parts by mass of isophorone diisocyanate, polycarbonate diol (T-5652 (registered trademark), manufactured by Asahi Kasei Chemicals Corporation) 45.56 parts by mass, 0.03 parts by mass of p-methoxyphenol and 0.02 parts by mass of dibutyltin dilaurate were added and heated to 70 ° C. with stirring. After stirring at 70 ° C. for 3 hours, 2.63 parts by mass 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 20000).

(Synthesis of polycarbonate urethane acrylate 2)
In a glass reaction vessel equipped with a thermometer, a stirrer, and a reflux tube, 45.01 parts by mass of methyl ethyl ketone, 6.26 parts by mass of isophorone diisocyanate, polycarbonate diol (T-5652 (registered trademark), manufactured by Asahi Kasei Chemicals Corporation) 47.02 parts by mass, p-methoxyphenol 0.03 parts by mass and dibutyltin dilaurate 0.02 parts by mass were added and heated to 70 ° C. with stirring. After stirring at 70 ° C. for 3 hours, 1.63 parts by mass 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 50000).

(Synthesis of polycarbonate urethane acrylate 3)
In a glass reaction vessel equipped with a thermometer, a stirrer, and a reflux tube, 45.01 parts by mass of methyl ethyl ketone, 5.89 parts by mass of isophorone diisocyanate, polycarbonate diol (T-5552 (registered trademark), manufactured by Asahi Kasei Chemicals Corporation) 48.20 parts by mass, 0.03 parts by mass of p-methoxyphenol and 0.02 parts by mass of dibutyltin dilaurate were added and heated to 70 ° C. with stirring. After stirring at 70 ° C. for 3 hours, 0.84 part by mass of 2-hydroxyethyl acrylate was added, and the mixture was further stirred for 3 hours to be reacted. 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 80000).

(Synthesis of polypropylene glycol urethane acrylate)
285.3 g of polypropylene glycol (number average molecular weight 2000) in a reaction vessel equipped with a cooling tube, thermometer, stirring device, dropping funnel and air introduction tube, unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone (Daicel Chemical Industries, Ltd.) 24.5 g, p-methoxyphenol 0.13 g as a polymerization inhibitor and 0.5 g of dibutyltin dilaurate as a catalyst, taking 15 minutes while flowing air at a flow rate of 100 mL / min. And heated from room temperature (25 ° C.) to 75 ° C. Thereafter, while maintaining the temperature at 75 ° C., 39.6 g of isophorone diisocyanate was added dropwise so as to be uniformly mixed over 2 hours to carry out the reaction. After completion of dropping, the reaction was allowed to proceed for 6 hours. It was confirmed that the isocyanate group had disappeared by measuring the infrared spectrum. At that time, the reaction was terminated to obtain polypropylene glycol urethane acrylate (weight average molecular weight 30000) having a polypropylene glycol residue and an isophorone diisocyanate residue as structural units and having (meth) acryloyl groups at both ends.

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. It is the determined value. In preparing the calibration curve, 5 sample sets (trade names “PStQuick MP-H”, “PStQuick B”, manufactured by Tosoh Corporation) were used as standard polystyrene.
Device: High-speed GPC device HLC-8320GPC (detector: differential refractometer)
(Product name, manufactured by Tosoh Corporation)
Solvent: Tetrahydrofuran (THF)
Column: Column TSKGEL SuperMultipore HZ-H
(Product name, manufactured by Tosoh Corporation)
Column size: Column length is 15 cm, column inner diameter is 4.6 mm
Measurement temperature: 40 ° C
Flow rate: 0.35 mL / min Sample concentration: 10 mg / THF 5 mL
Injection volume: 20 μL

(B) component:
Epoxy acrylate (mixture (weight ratio = 7/3) of compound obtained by reacting bisphenol A type phenoxy resin and acrylic acid (weight average molecular weight 950) and polyethylene glycol diacrylate (molecular weight 400), manufactured by Hitachi Chemical Co., Ltd. Product name "Hitaroid 7850")
(C) component:
PKHC (Bisphenol A type phenoxy resin, weight average molecular weight 45000, manufactured by InChem, trade name “PKHC”)
YP-70 (Bisphenol A-type and F-type copolymerized phenoxy resin, weight average molecular weight 50000, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., trade name “Phenototo YP-70”)
(D) component:
TPO (2,4,6-trimethylbenzoyl-diphenylphosphine oxide, manufactured by BASF Japan Ltd., trade name “LUCIRIN TPO”)
I-184 (1-hydroxycyclohexyl phenyl ketone, manufactured by BASF Japan Ltd., trade name “Irgacure-184”)

<Example 1>
[Preparation of adhesive sheet 1 (three-layer product)]
Using a polyethylene terephthalate having a thickness of 75 μm (made by Fujimori Kogyo Co., Ltd.) as the heavy release separator 3 and a polyethylene terephthalate having a thickness of 50 μm (made by Fujimori Kogyo Co., Ltd.) as the light release separator 4 and the temporary separator 6, the following The pressure-sensitive adhesive sheet 1 was produced by the procedures (I) to (V).

  (I) 40 parts by weight of polycarbonate urethane 1, 30 parts by weight of polycarbonate urethane acrylate 1, 30 parts by weight of bisphenol A type phenoxy resin (trade name “PKHC”, manufactured by InChem), 2,4,6-trimethylbenzoyl-diphenyl 1 part by weight of phosphine oxide (TPO) was weighed and diluted with 100 parts by weight of methyl ethyl ketone, followed by stirring and mixing to obtain a liquid adhesive resin composition at room temperature.

  (II) This adhesive resin composition was coated on the heavy release separator 3 so that the film thickness after drying was 150 μm. Subsequently, after drying a solvent in a 100 degreeC hot-air circulation type dryer and forming a coating film, the temporary separator 6 is laminated | stacked on the said coating film, and the adhesion layer 2 with the heavy peeling separator 3 and the temporary separator 6 is laminated | stacked. The laminated body which pinched | interposed was obtained.

  (III) The laminate was cut with a rotary blade having a diameter of 72 mm so as to have a size of 220 mm × 180 mm.

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

  (V) The temporary separator 6 was peeled off, and a light release separator 4 having a size of 215 mm × 170 mm was laminated on the adhesive layer 2. Thus, the adhesive sheet 1 was obtained. At this time, both sides on the long side of the light release separator 4 protrude 5 mm from both sides on the long side of the adhesive layer 2, and both sides on the short side of the light release separator 4 are from both sides on the short side of the adhesive layer 2. Lamination was performed so as to overhang 5 mm.

<Examples 2 to 12 and Comparative Examples 1 to 8>
A pressure-sensitive adhesive sheet 1 was obtained in the same manner as in Example 1 except that the blending amount was changed to the conditions shown in Table 2. In Tables 1 and 2, the unit of the numerical value representing the blending amount is part by mass.

[Various evaluations]
About the adhesive sheet obtained by each Example and the comparative example, the following (1)-(5) evaluation was performed and the result was shown in Table 1 and Table 2.

(1) Step embedding property The produced pressure-sensitive adhesive sheet is 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 is peeled off, and a cycloolefin polymer film having dimensions of 56 mm × 86 mm × 0.1 mm (Nippon ZEON Co., Ltd. make, brand name "ZEONOR film ZF16") was bonded using a hand roller (25 degreeC, load: 500gf). Next, after peeling off the polyethylene terephthalate film on the other side of the pressure-sensitive adhesive sheet on which the cycloolefin polymer film was not bonded, a step portion having a width of 9 mm and a thickness of 80 μm was provided on the outer peripheral portion. Using a vacuum bonding device (trade name “TPL-0512MH”, manufactured by Takatori Co., Ltd.) with a glass substrate having a size of 7 mm sandwiched between the adhesive layers, under the conditions of 80 ° C., 0.5 MPa, and a degree of vacuum of 50 Pa. Laminated for 60 seconds. Thereafter, treatment with an autoclave (60 ° C., 0.5 MPa) is performed for 30 minutes, and then ultraviolet rays are applied to the adhesive layer from the cycloolefin polymer film surface side using an ultraviolet irradiation device (made by Eye Graphics Co., Ltd.). An evaluation sample was irradiated with 2000 mJ / cm ² .
Using this evaluation sample, at 25 ° C., a laser measuring instrument (manufactured by Keyence Corporation, trade name “LT-9500”), a position controller (combs, trade name “CP-500”), and an automatic stage (combs) ), The surface shape of the cycloolefin polymer film side was measured with a three-dimensional shape measuring device comprising a computer. The difference in height (Δt, see FIG. 24) between the portion where the step portion was provided and the portion where the step portion was not provided was measured, and the step embedding property was evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: Less than 20 μm B: 20 μm or more and less than 40 μm C: 40 μm or more

(2) Turbidity (haze)
Cut out the prepared adhesive sheet into a size of 40 mm in width and 100 mm in length, peel off the polyethylene terephthalate film on one side of the adhesive sheet, and attach a hand roller to a glass substrate (soda lime glass) with dimensions of 50 mm × 100 mm × 3 mm. (25 ° C., load: 500 gf). Next, the polyethylene terephthalate film on the opposite surface of the pressure-sensitive adhesive sheet is peeled off, and the pressure-sensitive adhesive layer surface is used as a light source side, using a turbidimeter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name “NDH-5000”) to JIS K 7136. Measured accordingly.
Haze (%) = (Td / Tt) × 100
Td: diffuse transmittance Tt: total light transmittance

(3) Adhesiveness The prepared pressure-sensitive adhesive sheet was cut into a size of 10 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 a soda lime glass having a size of 25 mm in width and 100 mm in length was Lamination was performed using a roller (25 ° C., load: 500 gf). Next, the polyethylene terephthalate film on the other side of the pressure-sensitive adhesive sheet was peeled off, and a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., trade name “Cosmo Shine A4100”) was cut into dimensions of 15 mm in width and 150 mm in length, Laminated to an adhesive sheet. Using a tensile tester (trade name “RTC-1210” manufactured by Orientec Co., Ltd.), peel strength was measured at a peeling angle of 180 ° and a peeling speed of 300 mm / min in a temperature environment of 25 ° C. The adhesiveness was evaluated according to the evaluation criteria. The larger the value, the better the adhesion.
(Evaluation criteria)
A: 10 N / 10 mm or more B: 7 N / 10 mm or more and less than 10 N / 10 mm C: 5 N / 10 mm or more and less than 7 N / 10 mm D: Less than 5 N / 10 mm

(4) Light-shielding part curability The produced adhesive sheet was cut into dimensions of 10 mm in width and 30 mm in length, the polyethylene terephthalate film on one side of the adhesive sheet was peeled off, and a black printing layer (thickness 15 μm) was formed on the entire surface. The glass plate (50 mm × 10 mm) was bonded to the printed layer side using a hand roller. Next, the polyethylene terephthalate film on the other side of the pressure-sensitive adhesive sheet was peeled off, and a black polyethylene film was attached with a hand roller. Next, the printed layer side of the glass plate (50 mm × 10 mm) on which the black printed layer (thickness 15 μm) was formed was placed on the black polyethylene film and fixed with a clip. From the side surface of this laminate, ultraviolet rays were irradiated at 4000 mJ / cm ² using an ultraviolet irradiation device.
After irradiation, the sheet was cut with a width of 2 mm from the irradiated side of the adhesive sheet, and 3 mg was weighed on an aluminum sample pan for a differential scanning calorimeter. Next, using a differential scanning calorimeter capable of light irradiation (trade name “PDC121” manufactured by Seiko Instruments Inc.), the amount of change in the amount of heat associated with the photoreaction was measured (referred to as ΔH). Similarly, when the ultraviolet ray was not irradiated using the ultraviolet ray irradiation device, the amount of change in heat amount (referred to as ΔH (0)) associated with the photoreaction was measured, and the reaction rate was calculated from the following equation. The evaluation criteria were evaluated.
Reaction rate (%) = (ΔH (0) −ΔH) / ΔH (0) × 100
(Evaluation criteria)
A: 30% or more B: 10% or more and less than 30% C: less than 10%

(5) Dielectric constant After irradiating the prepared adhesive sheet with 2000 mJ / cm ^{2 of} ultraviolet rays using an ultraviolet irradiation device, it was cut into dimensions of 50 mm in width and 50 mm in length, and the polyethylene terephthalate film on one side of the adhesive sheet was peeled off. The glossy surface of a copper foil having a size of 100 mm × 100 mm × 18 μm (trade name “SLP-18”, manufactured by Nippon Electrolytic Co., Ltd.) was bonded so that the adhesive sheet did not protrude. Next, the polyethylene terephthalate film on the other side of the pressure-sensitive adhesive sheet is peeled off, and the pressure-sensitive adhesive sheet is placed on the glossy side of a copper foil having a size of 20 mm × 20 mm × 18 μm (trade name “SLP-18”, manufactured by Nippon Electrolytic Co., Ltd.). Lamination was done so as not to protrude. A terminal is brought into contact with the substantially central portion of each of a copper foil having a size of 100 mm × 100 mm and a copper foil having a size of 20 mm × 20 mm, and a temperature is measured by a dielectric constant measuring apparatus (manufactured by Agilent Technologies, trade name “LCR meter E4980”). The capacitance (C) was measured under the conditions of 25 ° C. and a frequency of 100 kHz, and a dielectric constant ε _r was calculated by the following equation. The evaluation results of each example and comparative example are shown in Table 1. Here, ε ₀ is the dielectric constant of vacuum, and d is the thickness of the adhesive layer.
C = ε ₀ × ε _r × (20 mm × 20 mm) / d

<Example 13>
[Preparation of adhesive sheet 1 (four-layer product)]
The pressure-sensitive adhesive sheet 1 of Example 13 was produced by the following procedures (I) to (V).
(I) A liquid adhesive resin composition was obtained in the same manner as in Example 1.
(II) After coating this adhesive resin composition on one side of the heavy release separator 3 and drying to form a coating film, the temporary separator 6 is laminated on the coating film, and then the heavy release separator. An acrylic adhesive (trade name “Hitalex K-6040” manufactured by Hitachi Chemical Co., Ltd.) was laminated on the other surface of 3, and a carrier film 5 was laminated thereon.
(III) The heavy release separator 3, the adhesive layer 2, the temporary separator 6 and the carrier film 5 were cut so as to be 220 mm × 180 mm.
(IV) The adhesive layer 2, the heavy release separator 3 and the temporary separator 6 were cut with a rotary blade having a diameter of 72 mm so as to have a size of 205 mm × 160 mm. For the cutting, a rotary punching device equipped with a rotary blade having a diameter of 72 mm was used. At this time, both sides on the long side of the carrier film 5 protrude 7.5 mm from both sides on the long side of the adhesive layer 2, and both sides on the short side of the carrier film 5 are from both sides on the short side of the adhesive layer 2. It cut | disconnected so that it might overhang 10 mm.
(V) The temporary separator 6 was peeled off, and a light release separator 4 having a size of 215 mm × 170 mm was laminated on the adhesive layer 2. Thus, the adhesive sheet 1 was obtained. At this time, both sides on the long side of the light release separator 4 protrude 5 mm from both sides on the long side of the adhesive layer 2, and both sides on the short side of the light release separator 4 are from both sides on the short side of the adhesive layer 2. Lamination was performed so as to overhang 5 mm.

  The pressure-sensitive adhesive sheet 1 (four-layer product) was evaluated in the same manner as the pressure-sensitive adhesive sheet 1 (three-layer product). As a result, a pressure-sensitive adhesive sheet having a desired shape could be produced. The results were excellent in all of embeddability, adhesiveness, haze, low dielectric constant, light-shielding part curability and appearance.

  In addition, the laminates of Examples 1 to 13 used in the light-shielding part curability test were peeled off and bubbled even after standing for 24 hours under the conditions of high temperature and high humidity (temperature 85 ° C., relative humidity 85%). Generation | occurrence | production of was not observed and it confirmed that it was excellent in the reliability under high temperature, high humidity.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive sheet for image display apparatuses provided with the adhesive layer which is excellent in transparency, a handleability, the level | step embedding property to a high level | step difference, and adhesiveness and also excellent in visibility can be provided. Moreover, after bonding an adherend, the adhesion force and holding | maintenance force of adhesion layer itself can be improved by accelerating | stimulating the crosslinking reaction of an adhesion layer. Since a device incorporating such an adhesive layer exhibits high reliability, the 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, 3 ... Heavy release separator (2nd base material layer), 4 ... Light release separator (1st base material layer), 5 ... Carrier film (carrier layer), 6 ... Temporary Separator, 2a, 3a, 4a ... outer edge, 3b, 5b ... adhesive layer side surface, 3c, 5c ... notch, 10 ... base material film, B ... blade, 40 ... transparent protective plate (glass or plastic substrate), DESCRIPTION OF SYMBOLS 7 ... Image display unit, 12 ... Liquid crystal display cell, 20, 22 ... Polarizing plate, 30 ... Touch panel, 31, 32 ... Transparent resin layer, 50 ... Backlight system, 60 ... Step part, 100 ... Jig.

Claims (11)

  (A) a pressure-sensitive adhesive layer containing a polycarbonate urethane having no (meth) acryloyl group, (B) a compound having an ethylenically unsaturated bond, (C) a phenoxy resin, and (D) a photopolymerization initiator, An adhesive sheet for an image display device, wherein the adhesive layer has a haze of 1.5% or less.   The pressure-sensitive adhesive sheet for an image display device according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 50 to 200 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 3, wherein outer edges of the first base material layer and the carrier layer project outward from the outer edge of the pressure-sensitive adhesive layer. The process of sticking together adherends and obtaining a layered product through the adhesive layer with which the adhesive sheet for image display devices according to any one of claims 1 to 4 is provided, and
Heating and pressurizing the laminate under conditions of 40 to 80 ° C. and 0.1 to 0.6 MPa;
Irradiating the adhesive layer in the laminate with ultraviolet rays;
A method for manufacturing an image display device.   The method for manufacturing an image display device according to claim 5, wherein the adherend is at least two selected from the group consisting of a transparent protective plate, a touch panel, and a liquid crystal display cell. An image display unit;
A transparent protective plate,
The transparent resin layer which is the said adhesive layer with which the adhesive sheet for image display apparatuses as described in any one of Claims 1-4 interposed between the said image display unit and the said transparent protective plate or its hardened | cured material is provided. ,
An image display device comprising: An image display unit;
A touch panel;
A transparent protective plate,
The transparent resin layer, which is the adhesive layer or the cured product thereof provided in the adhesive sheet for an image display device according to any one of claims 1 to 4, interposed between a touch panel and the transparent protective plate,
An image display device comprising:   The image display device according to claim 7, further comprising a step portion that forms a step in contact with the transparent resin layer on the image display unit or the transparent protective plate.   The image display device according to claim 8, further comprising a step portion that forms a step in contact with the transparent resin layer on the image display unit, the touch panel, or the transparent protective plate.   11. The image display device according to claim 9, wherein 0.4 <(h / t) <1 when the height of the stepped portion is h and the thickness of the transparent resin layer is t.

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