JPWO2013115250A1 - Photocurable transparent adhesive sheet composition, optical adhesive sheet - Google Patents

Abstract

Even if it is directly bonded to the conductive layer surface of the transparent conductive film, the conductive layer is not corroded. And the objective is to provide the composition for photocurable transparent adhesive sheets excellent in whitening resistance, and also an adhesive sheet. The present invention relates to a hydrogenated 1,2-polybutadiene-based acrylate compound or hydrogenated isoprene-based compound having a high molecular weight and a (meth) acryloyl group introduced, a (meth) acrylic acid ester having a hydroxyl group, a hydroxyl group It is related with the composition for photocurable transparent adhesive sheets which mix | blended polymerizable monomers other than (meth) acrylic acid ester which have alicyclic tackifying resin of the softening point of a specific range, and a photoinitiator.

Description

  The present invention relates to a photocurable transparent adhesive sheet composition, an optical adhesive sheet obtained by curing a photocurable transparent adhesive sheet composition, an optical adhesive sheet used for fixing a transparent resin plate, and a transparent conductive film. TECHNICAL FIELD The present invention relates to an optical pressure-sensitive adhesive sheet used for fixing a film, a touch panel using the optical pressure-sensitive adhesive sheet, and an image display device using the optical pressure-sensitive adhesive sheet.

  In recent years, in the fields of mobile phones, game machines, and the like, many image display devices such as liquid crystal displays and input devices used in combination with the image display devices such as touch panels have come to be seen. In these image display devices and input devices, transparent adhesive sheets are used for the purpose of bonding optical members.

  Touch panels using this transparent adhesive sheet mainly include a resistive film type touch panel that detects the pressure at the time of input and a capacitance type touch panel that detects an input location by static electricity from the human body at the time of input. In the capacitive touch panel, the conductive layer surface of a transparent conductive film such as ITO (indium tin oxide) is fixed so as to be in contact with the adhesive layer surface of the adhesive sheet. For this reason, when the pressure-sensitive adhesive layer is in contact with the conductive layer surface of the transparent conductive film, there is a problem that a metal oxidation reaction occurs due to the acid component contained in the pressure-sensitive adhesive, resulting in a decrease in the conductive function. For this reason, the adhesive sheet for fixing a transparent conductive film is required to have high metal corrosion prevention properties.

  As a pressure-sensitive adhesive sheet having a metal corrosion prevention property, a pressure-sensitive adhesive sheet containing a metal corrosion inhibitor (see, for example, Patent Document 1) has been proposed. Moreover, the adhesive sheet (for example, refer patent document 2) which reduced the corrosivity with respect to a transparent conductive film by containing the nitrogen atom containing component of a specific amount with respect to the acid component of an adhesive layer is proposed. .

  However, the pressure-sensitive adhesive sheet containing a metal corrosion inhibitor has a problem that the metal corrosion inhibitor is discolored in a durability test and optical properties are deteriorated. In addition, the pressure-sensitive adhesive sheet containing a specific amount of a nitrogen atom-containing component has a problem that an increase in the electrical resistance value of ITO cannot be sufficiently suppressed due to the acid component contained in the pressure-sensitive adhesive layer.

  Also, in mobile phones and game machines, weight reduction is important in terms of portability and handling during operation, and as a protective transparent plate on the front of touch panels, transparent resins such as acrylic plates and polycarbonate plates are used instead of glass plates. Plates are increasingly being used. However, when these resin plates are placed at a high temperature, gas is released from the inside of the resin plate, and the gas causes foaming at the interface between the transparent resin plate and the pressure-sensitive adhesive sheet, resulting in reduced visibility. .

  Conventionally, as a method for improving the foaming resistance under a high temperature and high humidity environment, a monomer having a high glass transition temperature (Tg) or a monomer containing a functional group such as a carboxyl group is copolymerized. Thus, a technique for increasing the Tg of the pressure-sensitive adhesive is known.

  For example, a pressure-sensitive adhesive composition excellent in adhesiveness and foam resistance to plastics at normal and high temperatures, comprising a polymer containing a carboxyl group-containing monomer as a constituent and an oligomer containing an amino group-containing monomer as a constituent (for example, a patent Document 3) is known. However, this pressure-sensitive adhesive composition is a pressure-sensitive adhesive composition containing a carboxyl group-containing polymer and has a problem that it cannot be used for laminating a transparent conductive film due to an acid component.

  Furthermore, even if it does not contain a carboxyl group-containing monomer component such as acrylic acid, an adhesive that crosslinks an acrylic polymer having a specific molecular weight mainly composed of an alkoxyalkyl acrylate in order to satisfy foam resistance at high temperatures A composition (see, for example, Patent Document 4) has been reported.

  However, although this pressure-sensitive adhesive composition is excellent in foaming resistance at high temperatures, there is a problem that the pressure-sensitive adhesive sheet is whitened under high temperature and high humidity.

  In short, at present, an excellent pressure-sensitive adhesive composition that achieves all characteristics such as foaming resistance, corrosion resistance, and whitening resistance under a high temperature and high humidity environment at a high level has not been obtained.

JP 2006-45315 A JP 2010-144002 A Japanese Patent No. 3516035 JP 2009-79203 A

  The problem to be solved by the present invention is that the conductive layer is not corroded even if directly bonded to the conductive layer surface of the transparent conductive film, and further, when used for fixing a transparent resin plate such as an acrylic plate or a polycarbonate plate Another object of the present invention is to provide a composition for a photocurable transparent pressure-sensitive adhesive sheet excellent in foam resistance and whitening resistance under a high-temperature and high-humidity environment, and further a pressure-sensitive adhesive sheet.

  As a result of intensive studies on the background of the above-mentioned problems of the photocurable transparent adhesive sheet for touch panel, the present inventors have a high molecular weight and hydrogenation in which a (meth) acryloyl group is introduced. 1,2-polybutadiene-based acrylate compound or hydrogenated isoprene-based compound, (meth) acrylic acid ester having a hydroxyl group, polymerizable monomer other than (meth) acrylic acid ester having a hydroxyl group, softening point of a specific range The composition for photocurable transparent adhesive sheet containing alicyclic tackifier resin and photopolymerization initiator is transparent, adhesive, metal corrosion prevention of transparent conductive film, anti-foaming when fixing transparent resin plate And the whitening resistance under high temperature and high humidity was found to be satisfactory, and the present invention was completed based on this finding.

  The present invention is shown by the following (1) to (9).

  (1) (A) Hydrogenated 1,2-polybutadiene polyol or hydrogenated polyisoprene polyol is reacted with a polyfunctional isocyanate compound, and the remaining hydroxyl group or isocyanate group, (meth) acryloyl group, and isocyanate group or hydroxyl group The (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or the (meth) acryloyl group-containing hydrogenated polyisoprene compound having a weight average molecular weight of 50,000 to 200,000 obtained by reacting the compound having 25 to 45% by mass (B) (meth) acrylic acid ester having a hydroxyl group of 8 to 20% by mass, (C) polymerizable monomer other than (meth) acrylic acid ester having a hydroxyl group of 20 to 61.8% by mass, (D ) Photopolymerization initiator 0.2 to 5% by mass, and (E) Softening point is 90 to 150 ° C. Cyclic tackifier resin 5 to 20 wt% photo-curable transparent adhesive sheet composition comprising a.

  (2) The composition for photocurable transparent adhesive sheets according to (1), wherein the acid value is 0 to 5 mgKOH / g.

  (3) The composition for a photocurable transparent pressure-sensitive adhesive sheet according to any one of (1) and (2), wherein the weight average molecular weight of the (E) alicyclic tackifying resin is 500 to 1500.

  (4) Theory of a copolymer obtained by copolymerizing (B) a (meth) acrylic acid ester having a hydroxyl group and (C) a polymerizable monomer other than a (meth) acrylic acid ester having a hydroxyl group The composition for photocurable transparent adhesive sheets in any one of said (1)-(3) whose glass transition temperature is 0 degreeC-50 degreeC.

  (5) The light according to any one of (1) to (4), wherein the (meth) acryloyl group and the compound having an isocyanate group or a hydroxyl group are hydroxyalkyl (meth) acrylate or isocyanate group-containing (meth) acrylate. A composition for a curable transparent adhesive sheet.

  (6) The composition for a photocurable transparent adhesive sheet according to any one of (1) to (5), wherein the polyfunctional isocyanate compound is a hydrogenated diphenylmethane diisocyanate or isophorone diisocyanate.

  (7) An optical pressure-sensitive adhesive sheet obtained by curing the photocurable transparent pressure-sensitive adhesive sheet composition according to any one of (1) to (6).

  (8) The optical pressure-sensitive adhesive sheet according to (7), which is used for fixing a transparent resin plate.

  (9) The optical pressure-sensitive adhesive sheet according to (7), which is used for fixing the transparent conductive film.

  (10) A touch panel using the optical pressure-sensitive adhesive sheet according to (7).

  (11) An image display device using the optical pressure-sensitive adhesive sheet according to (7).

  The composition for a photocurable transparent pressure-sensitive adhesive sheet of the present invention contains a hydrogenated 1,2-polybutadiene compound or a hydrogenated isoprene compound having a high molecular weight and having a (meth) acryloyl group introduced therein. Therefore, an adhesive sheet excellent in flexibility, adhesiveness, cohesive force, moisture permeability resistance, and water resistance can be obtained. Moreover, since the alicyclic tackifying resin having a softening point in a specific range is contained in the composition, foaming when the transparent resin plates are bonded together under high temperature and high humidity can be suppressed. Furthermore, by setting the content of the carboxyl group in the composition to a predetermined amount or less, corrosion of the conductive layer surface of the transparent conductive film due to the acid component can be suppressed, and the (meth) acrylic acid ester having a hydroxyl group in the composition can be suppressed. By making the amount within a specific range, whitening of the pressure-sensitive adhesive sheet under high humidity can be prevented. Therefore, by using the pressure-sensitive adhesive sheet of the present invention, the visibility under high temperature and high humidity becomes good and can be suitably used for a touch panel.

  Hereinafter, the present invention will be described in detail.

(Photocurable transparent adhesive sheet composition)
The composition for a photocurable transparent pressure-sensitive adhesive sheet of the present invention comprises (A) a hydrogenated 1,2-polybutadiene polyol or a hydrogenated polyisoprene polyol and a polyfunctional isocyanate compound, and a remaining hydroxyl group or isocyanate group (—N = C = O), a (meth) acryloyl group and a (meth) acryloyl group-containing hydrogenated 1,2- having a weight average molecular weight of 50,000 to 200,000 obtained by reacting a compound having an isocyanate group or a hydroxyl group Polybutadiene compound or (meth) acryloyl group-containing hydrogenated polyisoprene compound 25 to 45% by mass, (B) 8 to 20% by mass of (meth) acrylic acid ester having a hydroxyl group, (C) (meth) acryl having a hydroxyl group 20 to 61.8% by mass of a polymerizable monomer other than the acid ester, (D) a photopolymerization initiator; 5% by weight, and (E) a softening point of photocurable transparent adhesive sheet composition containing 5 to 20 wt% cycloaliphatic tackifying resin is 90 to 150 ° C.. Hereinafter, each component will be described.

((A) (Meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or (meth) acryloyl group-containing hydrogenated polyisoprene compound)
The hydrogenated 1,2-polybutadiene refers to a compound obtained by reacting hydrogen with a double bond portion (—CH═CH—) of 1,2-polybutadiene to change to a single bond (—CH ₂ —CH ₂ —). . The same applies to hydrogenated polyisoprene. The (A) (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or (meth) acryloyl group-containing hydrogenated polyisoprene compound of the present invention includes a hydrogenated 1,2-polybutadiene polyol or a hydrogenated polyisoprene polyol, It can be obtained by reacting a polyfunctional isocyanate compound and then reacting the remaining hydroxyl group or isocyanate group with a (meth) acryloyl group and a compound having an isocyanate group or hydroxyl group.

Examples of the synthesis method of (A) (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or (meth) acryloyl group-containing hydrogenated polyisoprene compound include the following two-stage reactions. Here, the (meth) acryloyl group _CH 2 = _CH-CO-, or _CH 2 _{= C} (CH 3) means a -CO-.

  A two-step reaction as a first example is as follows. First, a polyfunctional isocyanate compound having two or more isocyanate groups in one molecule with respect to hydrogenated 1,2-polybutadiene polyol or hydrogenated polyisoprene polyol (hereinafter sometimes referred to as “polyfunctional isocyanate compound”). Is reacted at a ratio in which the amount of isocyanate groups is larger than the amount of hydroxyl groups to synthesize a urethane prepolymer having an isocyanate group with an extended chain length. At this time, the molecular weight can be adjusted by adjusting the hydroxyl group amount of the hydrogenated 1,2-polybutadiene polyol or the hydrogenated polyisoprene polyol and the isocyanate group amount of the polyfunctional isocyanate compound. The greater the amount of hydroxyl groups relative to the isocyanate groups, the greater the molecular weight of the resulting polyurethane compound, and the smaller the amount of hydroxyl groups relative to the amount of isocyanate groups, the smaller the molecular weight of the resulting polyurethane compound. Next, as a (meth) acrylate having a hydroxyl group in the obtained urethane prepolymer, a hydroxyalkyl (meth) acrylate or a (meth) acrylate monool derived from various polyols (with one hydroxyl group remaining, various polyols ( (Meth) acrylated) is reacted to convert the remaining isocyanate group to a (meth) acryloyl group, thereby (A) a (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or (meth) acryloyl group A hydrogenated polyisoprene compound is obtained. Specific examples of the hydroxyalkyl (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,3-butanediol (meth) acrylate, Examples include 1,4-butanediol (meth) acrylate, 1,6-hexanediol (meth) acrylate, 3-methylpentanediol (meth) acrylate, and the like, which can be used alone or in combination of two or more. Among these, 2-hydroxyethyl acrylate is preferable in terms of reactivity with an isocyanate group and photocurability. At this time, the (meth) acryloyl group content can be adjusted by reacting the alkyl alcohol with an isocyanate group. The saturated alcohol that can be used is not particularly limited, and one or more linear, branched, and alicyclic alkyl alcohols can be used.

  A two-step reaction as a second example is as follows. First, a polyfunctional isocyanate compound is reacted with hydrogenated 1,2-polybutadiene polyol or hydrogenated polyisoprene polyol at a ratio in which the amount of hydroxyl groups is greater than the amount of isocyanate groups to synthesize a polyurethane compound having a hydroxyl group with an extended chain length. To do. At this time, the molecular weight can be adjusted by adjusting the hydroxyl group amount of the hydrogenated 1,2-polybutadiene polyol or the hydrogenated polyisoprene polyol and the isocyanate group amount of the polyfunctional isocyanate compound. The greater the amount of hydroxyl groups relative to the isocyanate groups, the greater the molecular weight of the resulting polyurethane compound, and the smaller the amount of hydroxyl groups relative to the amount of isocyanate groups, the smaller the molecular weight of the resulting polyurethane compound. Next, an isocyanate group-containing (meth) acrylate is reacted with the obtained polyurethane compound to obtain a (A) (meth) acrylate group-containing polyolefin compound. At this time, the content of the (meth) acryloyl group can be adjusted by adjusting the amount of the isocyanate group-containing (meth) acrylate to be reacted with the remaining hydroxyl group. As the isocyanate group-containing (meth) acrylate, a commercially available compound may be used, or a hydroxyalkyl (meth) acrylate or (meth) acrylate monool derived from various polyols and a diisocyanate compound are reacted to form an isocyanate group at one end, What synthesized the isocyanate group containing (meth) acrylate which has a (meth) acryloyl group in the other terminal may be used. Examples of the isocyanate group-containing (meth) acrylate include 2-isocyanatoethyl (meth) acrylate and 1,1-bis (acryloyloxymethyl) ethyl isocyanate. Among these, 2-isocyanatoethyl acrylate is preferable from the viewpoint of reactivity with a hydroxyl group and photocurability.

  The two-step reaction in the above two examples is a reaction between a hydroxyl group and an isocyanate group, and a general urethane such as dibutyltin dilaurate or dibutyltin diethylhexoate in the presence of an organic solvent inert to the isocyanate group. The reaction is usually carried out at 30 to 100 ° C. for about 1 to 5 hours using the catalyst. The amount of the urethanization catalyst used is usually 50 to 500 ppm based on the total mass of the raw materials used for the reaction.

  The hydrogenated 1,2-polybutadiene polyol or hydrogenated polyisoprene polyol used in the present invention preferably has a number average molecular weight of 500 to 5000, and more preferably 1000 to 4000. When the number average molecular weight is smaller than 500, the number of urethane bonds in the (A) (meth) acryloyl group-containing hydrogenated polybutadiene compound or (meth) acryloyl group-containing hydrogenated polyisoprene compound is too large, so the yellowing resistance is poor. There is a possibility. When the number average molecular weight is greater than 5,000, the phase of (A) (meth) acryloyl group-containing hydrogenated polybutadiene compound or (meth) acryloyl group-containing hydrogenated polyisoprene compound and (meth) acrylic acid ester having a hydroxyl group The solubility tends to deteriorate, which is not preferable. The hydroxyl value of the hydrogenated 1,2-polybutadiene polyol or hydrogenated polyisoprene polyol is preferably 10 to 200 mgKOH / g, more preferably 15 to 100 mgKOH / g, and 25 to 75 mgKOH / g. Further preferred. When the hydroxyl value of the hydrogenated 1,2-polybutadiene polyol or hydrogenated polyisoprene polyol is larger than 200 mgKOH / g, the urethane bond becomes too much, so that yellowing resistance may be deteriorated, and if it is smaller than 10 mgKOH / g, (A) The (meth) acryloyl group-containing hydrogenated polybutadiene compound or the (meth) acryloyl group-containing hydrogenated polyisoprene compound and the (meth) acrylic acid ester having a hydroxyl group tend to deteriorate, which is not preferable. As a commercially available product of hydrogenated 1,2-polybutadiene polyol that can be used in the present invention, specifically, Nippon Soda Co., Ltd., product names: GI-1000, GI-2000, GI-3000 (number average molecular weight is About 1500, about 2100, and about 3000), respectively. Specific examples of commercially available hydrogenated polyisoprene polyols include Idemitsu Kosan Co., Ltd. product name Epol (number average molecular weight of about 2500).

  Examples of the polyfunctional isocyanate compound used in the present invention include diisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, and hydrogenated products thereof, hexamethylene diisocyanate, trimethyl hexaxane. Examples thereof include diisocyanate compounds such as methylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexyl diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, and norbornane diisocyanate. Of these, isophorone diisocyanate or hydrogenated diphenylmethane diisocyanate is preferred from the viewpoint of light resistance and ease of reactivity control. These compounds having two or more isocyanate groups in one molecule can be used alone or in combination of two or more.

  The (A) (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or (meth) acryloyl group-containing hydrogenated polyisoprene compound of the present invention includes a hydrogenated 1,2-polybutadiene polyol or a hydrogenated polyisoprene polyol, It is preferable that the polyfunctional isocyanate compound is reacted to increase the molecular weight and then introduce 80 to 100 mol% of (meth) acryloyl group with respect to the remaining hydroxyl group or isocyanate group. More preferably, 90-100 mol% (meth) acryloyl groups are introduced with respect to the remaining hydroxyl groups or isocyanate groups. When the ratio of introducing the (meth) acryloyl group is less than 80 mol%, the cohesive force of the obtained pressure-sensitive adhesive sheet becomes small, and when the pressure-sensitive adhesive sheet is bonded to a transparent resin plate, the foam resistance may deteriorate. There is sex.

The weight average molecular weight of the (A) (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or (meth) acryloyl group-containing hydrogenated polyisoprene compound is 50,000 to 200,000, preferably 60,000 to 150,000. More preferably, it is 70,000 to 100,000. The molecular weight can be adjusted by adjusting the amounts of the hydrogenated 1,2-polybutadiene polyol or hydrogenated polyisoprene polyol and the polyfunctional isocyanate compound. When the weight average molecular weight is less than 50,000, the cohesive force of the obtained pressure-sensitive adhesive sheet is small, and when the pressure-sensitive adhesive sheet is bonded to a transparent resin plate, the strength of the foam-resistant pressure-sensitive adhesive sheet may not be sufficient. On the other hand, when the molecular weight is larger than 200,000, the viscosity of the photocurable transparent pressure-sensitive adhesive sheet composition becomes too high, and handling becomes difficult and workability is remarkably deteriorated. In addition, the value of the weight average molecular weight in this invention is measured at normal temperature on the following conditions using gel permeation chromatography (Showa Denko Co., Ltd. Shodex GPC-101), and is calculated by polystyrene conversion. Is.
Column: Showa Denko LF-804
Column temperature: 40 ° C
Sample: 0.2 mass% copolymer solution in tetrahydrofuran Flow rate: 1 ml / min Eluent: Tetrahydrofuran

  (A) The content of the (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or the (meth) acryloyl group-containing hydrogenated polyisoprene compound is 25 to 45% by mass in the photocurable transparent adhesive sheet composition. Yes, it is preferably 28 to 40% by mass, and more preferably 30 to 35% by mass. When the content of the (A) (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or the (meth) acryloyl group-containing hydrogenated polyisoprene compound in the photocurable transparent adhesive sheet composition is less than 25% by mass When the obtained pressure-sensitive adhesive sheet is bonded to a transparent resin plate, the water resistance at high temperature and high humidity may deteriorate, and the foam resistance may deteriorate. On the other hand, the content of the (A) (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or the (meth) acryloyl group-containing hydrogenated polyisoprene compound in the composition for a photocurable transparent adhesive sheet is more than 45% by mass. In some cases, the adhesive strength of the resulting adhesive sheet may be reduced.

((B) (Meth) acrylic acid ester having hydroxyl group)
(B) As (meth) acrylic acid ester which has a hydroxyl group, what does not have a carboxyl group is preferable, For example, the hydroxyalkyl (meth) acrylate etc. whose carbon number of an alkyl group is 2-7 are mentioned. Specific examples thereof include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,3-butanediol (meth) acrylate, and 1,4-butane. Examples include diol (meth) acrylate, 1,6-hexanediol (meth) acrylate, and 3-methylpentanediol (meth) acrylate, which can be used alone or in combination of two or more. (B) As carbon number of the alkyl group of the (meth) acrylic acid ester which has a hydroxyl group, 1-6 are preferable and 2-4 are more preferable. Especially, 2-hydroxyethyl acrylate is preferable at the point of the adhesive force of the adhesive sheet obtained. (B) Content of the (meth) acrylic acid ester which has a hydroxyl group is 8-20 mass% in the composition for photocurable transparent adhesive sheets, Preferably it is 9-18 mass%, More preferably, it is 10 ˜15 mass%. If the content of the (B) hydroxyl group-containing (meth) acrylic acid ester in the photocurable transparent adhesive sheet composition is less than 8% by mass, the adhesiveness of the resulting adhesive sheet to the substrate becomes insufficient. In some cases, the pressure-sensitive adhesive sheet may be whitened under high humidity. Moreover, when the content of the (B) hydroxyl group-containing (meth) acrylic acid ester in the photocurable transparent adhesive sheet composition is more than 20% by mass, the water resistance of the adhesive sheet may be deteriorated. is there.

((C) Polymerizable monomer other than (meth) acrylic acid ester having hydroxyl group)
(C) A polymerizable monomer other than the (meth) acrylic acid ester having a hydroxyl group (hereinafter sometimes referred to as “(C) polymerizable monomer”) is a photopolymerizable monomer. In addition, the (B) component other than the (meth) acrylic acid ester having a hydroxyl group. The polymerizable monomer (C) is preferably a monomer that does not contain a carboxyl group (chemical formula: —COOH). The monomer is not particularly limited, and monofunctional or polyfunctional photopolymerizable monomers having a vinyl group, a (meth) acryloyl group, or the like can be used alone or in combination of two or more. The monofunctional or polyfunctional functional group here refers to a vinyl group or a (meth) acryloyl group. Examples of the polymerizable monomer (C) of the present invention include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and tert-butyl (meth). Alkyl such as acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, n-hexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate (Meth) acrylate, cyclohexyl (meth) acrylate, norbornyl (meth) acrylate, isobornyl (meth) acrylate, norbornanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyl Kishiechiru (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentanyl oxyethyl (meth) acrylate, tricyclodecane dimethylol di (meth) cyclic alkyl acrylates such as (meth) acrylate. Alkoxyalkyl (meth) acrylates such as ethoxyethyl (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, 2-methoxyethoxyethyl (meth) acrylate, 2-ethoxyethoxyethyl (meth) acrylate, methoxy Fluorinated alkyl (meth) acrylates such as alkoxy (poly) alkylene glycol (meth) acrylates such as diethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, and octafluoropentyl (meth) acrylate , N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate and the like dialkylaminoal (Meth) acrylate, polyethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, hydroxypivalin Acid ester neopentyl glycol di (meth) acrylate, 1,3-bis (hydroxyethyl) -5,5-dimethylhydantoin di (meth) acrylate, α, ω-di (meth) acrylbisdiethylene glycol phthalate, trimethylolpropane tri (Meth) acrylate, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,4 Polyfunctionality such as butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, diacryloxyethyl phosphate, dipentaerythritol trihydroxy (meth) acrylate, pentaerythritol tetra (meth) acrylate ( Examples thereof include acrylamide derivatives such as (meth) acrylate, acrylamide, dimethylacrylamide, diethylacrylamide, and (meth) acryloylmorpholine, and epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate. As the polymerizable monomer (C) of the present invention, miscibility with (A) (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or (meth) acryloyl group-containing hydrogenated polyisoprene compound, Alkyl (meth) acrylate or cyclic alkyl (meth) acrylate is preferred from the viewpoints of the tackiness, strength, light resistance and heat resistance of the pressure-sensitive adhesive sheet. The content of the polymerizable monomer (C) is 20 to 61.8% by mass, preferably 30 to 55% by mass, and more preferably 35 to 35% by mass in the photocurable transparent adhesive sheet composition. 50% by mass. When the content of the polymerizable monomer (C) in the photocurable transparent adhesive sheet composition is less than 20% by mass, the adhesiveness of the resulting adhesive sheet to the substrate may be insufficient. In addition, when the content of the polymerizable monomer (C) in the photocurable transparent adhesive sheet composition is more than 61.8% by mass, the cohesive force of the obtained adhesive sheet becomes small, and the adhesive sheet becomes When bonded to a transparent resin plate, the strength of the foam-resistant pressure-sensitive adhesive sheet may not be sufficient.

The theoretical glass transition temperature of the copolymer obtained by copolymerizing only the (B) hydroxyl group-containing (meth) acrylate ester and the polymerizable monomer (C) of the present invention is the strength of the adhesive sheet, adhesion From the viewpoint of force, the temperature is preferably 0 to 50 ° C, more preferably 5 to 45 ° C, and further preferably 10 to 40 ° C. When the temperature is lower than 0 ° C., the pressure-sensitive adhesive sheet obtained is too soft due to the influence of the (A) (meth) acryloyl group-containing polyolefin compound, and thus the adhesive strength of the pressure-sensitive adhesive sheet is lowered, which is not preferable. Moreover, when higher than 50 degreeC, since the adhesive sheet obtained becomes too hard and sufficient adhesiveness is not acquired, it is unpreferable. Here, the theoretical glass transition temperature (Tg) is the following fox (FOX) based on the Tg of the homopolymer (homopolymer) of each monomer constituting the monomer raw material and the mass fraction (copolymerization ratio) of the monomer. It can be calculated from the equation (1).

Is _{W 1, W} 2 ··· _{W n} is the mass fraction of each monomer in the formula (1) (= (amount / monomer total weight of each _{monomer)), T 1, T 2} ··· T n Is the glass transition temperature (absolute temperature) of the homopolymer of each monomer. As the Tg of the homopolymer, a value described in “Adhesion Technology Handbook” of Nikkan Kogyo Shimbun Co., Ltd. or “Polymer Handbook” of Wiley-Interscience, which is a publicly known material, is adopted. For the Tg of a homopolymer obtained by polymerizing monomers not described in the above-mentioned publicly known materials, the value obtained by the following method is adopted. That is, a test sample is prepared by casting and drying a homopolymer solution obtained by solution polymerization of a target monomer on a release liner. With respect to this test sample, a differential scanning calorimeter (DSC) was used to perform differential scanning calorimetry at a temperature rising rate of 10 ° C./min from −80 ° C. to 280 ° C., and an endothermic start temperature due to glass transition. Is adopted as the Tg of the homopolymer.

((D) Photopolymerization initiator)
Examples of the (D) photopolymerization initiator in the present invention include a carbonyl photopolymerization initiator, a sulfide photopolymerization initiator, a quinone photopolymerization initiator, an azo photopolymerization initiator, and a sulfochloride photopolymerization initiator. Thioxanthone photopolymerization initiator, peroxide photopolymerization initiator, and the like.

  Examples of the carbonyl photopolymerization initiator include benzophenone, benzyl, benzoin, ω-bromoacetophenone, chloroacetone, acetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, p-dimethylamino. Acetophenone, p-dimethylaminopropiophenone, 2-chlorobenzophenone, p, p'-dichlorobenzophenone, p, p'-bisdiethylaminobenzophenone, Michler's ketone, benzoin methyl ether, benzoin isobutyl ether, benzoin-n-butyl ether, benzylmethyl Ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- (4-isopropylphenyl) -2- Droxy-2-methylpropan-1-one, methylbenzoylformate, 2,2-diethoxyacetophenone, 4-N, N′-dimethylacetophenone, 2-methyl-1- [4- (methylthio) phenyl] -2 -Morpholinopropan-1-one and the like.

  Examples of the sulfide photopolymerization initiator include diphenyl disulfide, dibenzyl disulfide, tetraethylthiuram disulfide, and tetramethylammonium monosulfide. Examples of the quinone photopolymerization initiator include benzoquinone and anthraquinone. Examples of the azo photopolymerization initiator include azobisisobutyronitrile, 2,2'-azobispropane, hydrazine, and the like. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, and 2-methylthioxanthone. Examples of the peroxide photopolymerization initiator include benzoyl peroxide and di-t-butyl peroxide. Among these (D) photopolymerization initiators, 1-hydroxy-cyclohexyl-phenyl-ketone is preferable from the viewpoint of solubility in the resulting photocurable transparent adhesive sheet composition. These (D) photopolymerization initiators are used alone or in combination of two or more.

  (D) Content of a photoinitiator is 0.2-5 mass% in the composition for photocurable transparent adhesive sheets from the point of balance of photocurability, the intensity | strength of the adhesive sheet obtained, and adhesiveness. , Preferably it is 0.5-3 mass%, More preferably, it is 0.8-2 mass%. When the content of the (D) photopolymerization initiator in the photocurable transparent adhesive sheet composition is less than 0.2% by mass, the photocuring tends to be insufficient. When the content of the (D) photopolymerization initiator in the composition for a photocurable transparent adhesive sheet exceeds 5% by mass, the adhesiveness of the obtained adhesive sheet tends to decrease.

((E) Alicyclic tackifying resin having a softening point of 90 to 150 ° C.)
Generally, tackifying resins are called tackifiers, and have the function of bringing out tackiness when mixed with polymers (elastomers) typified by various types of plastics and rubber. Among them, the alicyclic tackifying resin means a tackifying resin made of a cyclic hydrocarbon resin having no unsaturated bond (double bond or triple bond). (E) The alicyclic tackifying resin having a softening point of 90 to 150 ° C. of the present invention includes an unsaturated group having a softening point of 90 to 150 ° C. based on the ring and ball method defined in JIS K-2207. It is preferable that there is no resin. A more preferable softening point range is 95 to 145 ° C, and further preferably 100 to 140 ° C. When the softening point is lower than 90 ° C., the heat resistance of the pressure-sensitive adhesive sheet at high temperatures is insufficient, and the foam resistance may be deteriorated when the pressure-sensitive adhesive sheet is bonded to the transparent resin plate. When the softening point is higher than 150 ° C., the solubility in (meth) acrylic acid ester tends to be low.

  It is preferable that the weight average molecular weight of (E) alicyclic tackifying resin of this invention is 500-1500. More preferably, it is 1000-1400. (E) If the weight average molecular weight of the alicyclic tackifying resin is smaller than 500, the resulting pressure-sensitive adhesive sheet has insufficient heat resistance, and the foam resistance is poor when the pressure-sensitive adhesive sheet is bonded to a transparent resin plate. There is a possibility. When the weight average molecular weight is greater than 1500, the solubility in (meth) acrylic acid ester tends to be low. (E) Alicyclic tackifier resins include rosin and rosin derivative hydrogenated resins, polyterpene resin hydrogenated resins, aromatic modified terpene resin hydrogenated resins, terpene phenol resin hydrogenated resins, coumarone indene resins Hydrogenated resin, alicyclic petroleum resin hydrogenated resin, aromatic petroleum resin hydrogenated resin, aliphatic aromatic copolymer petroleum resin hydrogenated resin, dicyclopentadiene petroleum resin hydrogenated resin Examples thereof include hydrogenated resins of dicyclopentadiene aromatic copolymer, and hydrogenated resins of low molecular weight polymers of styrene or substituted styrene. From the viewpoint of heat resistance and light resistance, terpene hydrogenated resins may be used. preferable. (E) An alicyclic tackifier resin can be used individually or in combination of 2 or more types.

  (E) Content of alicyclic tackifying resin is 5-20 mass% in the composition for photocurable transparent adhesive sheets from the point of balance of photocurability, the intensity | strength of the adhesive sheet obtained, and adhesiveness. , Preferably it is 7-15 mass%, More preferably, it is 9-11 mass%. (E) When content of alicyclic tackifying resin is less than 5 mass%, there exists a possibility that the adhesiveness of an adhesive sheet may become inadequate. When it exceeds 20% by mass, the tackiness of the obtained pressure-sensitive adhesive sheet tends to be too high, and the handleability tends to be lowered.

  The composition for a photocurable transparent adhesive sheet of the present invention is based on (A) (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or (meth) with respect to the total amount of the photocurable transparent adhesive sheet composition. 25-45% by mass of acryloyl group-containing hydrogenated polyisoprene compound, (B) 8-20% by mass of (meth) acrylic acid ester having hydroxyl group, (C) polymerizability other than (meth) acrylic acid ester having hydroxyl group It contains 20 to 61.8% by mass of a monomer, (D) 0.2 to 5% by mass of a photopolymerization initiator, and (E) 5 to 20% by mass of an alicyclic tackifying resin. Preferably, (A) the (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or the (meth) acryloyl group-containing hydrogenated polyisoprene compound 28 with respect to the total amount of the photocurable transparent adhesive sheet composition. -40 mass%, (B) 9-18 mass% of (meth) acrylic acid ester having a hydroxyl group, (C) 30-55 mass% of polymerizable monomer other than (meth) acrylic acid ester having a hydroxyl group, (D) It contains 0.5 to 3% by mass of a photopolymerization initiator, and (E) 7 to 15% by mass of an alicyclic tackifying resin. And more preferably, (A) (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or (meth) acryloyl group-containing hydrogenated polyisoprene compound with respect to the total amount of the photocurable transparent adhesive sheet composition. 30-35% by mass, (B) 10-15% by mass of (meth) acrylic acid ester having a hydroxyl group, (C) 35-50% by mass of polymerizable monomer other than (meth) acrylic acid ester having a hydroxyl group (D) 0.8-2 mass% of photoinitiators, and (E) 9-11 mass% of alicyclic tackifying resin are contained.

  The acid value of the composition for a photocurable transparent adhesive sheet of the present invention is preferably 0 to 5 mgKOH / g, more preferably 0 to 0.5 mgKOH / g, and further preferably 0 to 0.1 mgKOH / g. When the acid value is higher than 5 mgKOH / g, it becomes difficult to suppress corrosion of the conductive layer surface of the transparent conductive film. In addition, the acid value of the composition for photocurable transparent adhesive sheets in this case is the value measured based on JISK0070. For example, measurement is performed as follows.

Ｂ：０．１Ｎ水酸化カリウム−エタノール溶液の使用量（ｍｌ）
ｆ：０．１Ｎ水酸化カリウム−エタノール溶液のファクター
Ｓ：試料の採取量（ｇ）About 2 g of a sample is precisely weighed in a 100 ml Erlenmeyer flask with a precision balance, and 10 ml of a mixed solvent of ethanol / diethyl ether = 1/1 (weight ratio) is added to dissolve it. Further, 1 to 3 drops of phenolphthalein ethanol solution is added to this container as an indicator, and the mixture is sufficiently stirred until the sample becomes uniform. This is titrated with a 0.1N potassium hydroxide-ethanol solution, and the end point of neutralization is taken when the indicator is light red for 30 seconds. The value obtained from the result using the following calculation formula (2) is taken as the acid value of the photocurable transparent adhesive sheet composition.

B: Amount of 0.1N potassium hydroxide-ethanol solution used (ml)
f: Factor of 0.1N potassium hydroxide-ethanol solution S: Amount of sample collected (g)

  Moreover, the composition for photocurable transparent adhesive sheets of this invention may contain various well-known additives in the range which does not impair transparency as needed. Additives include plasticizers, surface lubricants, leveling agents, softeners, antioxidants, antioxidants, light stabilizers, UV absorbers, polymerization inhibitors, benzotriazole-based light stabilizers, phosphate esters System and other flame retardants, and antistatic agents such as surfactants.

  Moreover, the composition for photocurable transparent adhesive sheets of this invention is good also as a solution using an organic solvent for the purpose of the viscosity adjustment at the time of coating. Examples of the organic solvent used include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, n-propanol, and isopropanol. These organic solvents may be used alone or in combination of two or more.

(Optical adhesive sheet)
The optical pressure-sensitive adhesive sheet of the present invention is an optical pressure-sensitive adhesive sheet used for optical applications obtained by curing the composition for a photocurable transparent pressure-sensitive adhesive sheet. More specifically, it is used for applications for bonding optical members (for optical member bonding), optical product manufacturing applications, and the like. Moreover, even if it has a base material, the double-sided adhesive sheet which does not have a base material but consists only of an adhesive layer may be sufficient as the adhesive sheet for optics of this invention. Although it will not specifically limit if it is a member which has an optical characteristic as an optical member, For example, the member used for an image display apparatus, a touchscreen, or these apparatuses is mentioned, For example, a polarizing plate, phase difference, etc. Plate, optical compensation film, brightness enhancement film, light guide plate, reflection film, antireflection film, transparent conductive film, design film, decorative film, surface protection film, prism, lens, color filter, transparent substrate, and these are laminated The member currently made is mentioned.

  The optical pressure-sensitive adhesive sheet can be obtained by applying a photocurable transparent pressure-sensitive adhesive sheet composition to a release film, and irradiating the applied composition with ultraviolet rays using an ultraviolet irradiation device or the like to cause photocuring. The film thickness of the optical pressure-sensitive adhesive sheet is preferably 5 to 500 μm, more preferably 10 to 400 μm, and still more preferably 15 to 300 μm. When the film thickness of the optical pressure-sensitive adhesive sheet is thinner than 5 μm, it tends to be difficult to bond the pressure-sensitive adhesive sheet. When the film thickness of the optical pressure-sensitive adhesive sheet is thicker than 500 μm, it tends to be difficult to control the film thickness. In addition, for coating (coating) in the method for forming an optical pressure-sensitive adhesive sheet of the present invention, a known coating method can be used. Conventional coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters Dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, direct coaters and the like can be used.

  The surface (adhesive surface) of the optical pressure-sensitive adhesive sheet of the present invention may be protected by a release film (separator) until use. In addition, each adhesive surface (both surfaces) of the adhesive sheet may be protected by two release films, respectively, or is wound into a roll by one release film having both surfaces as release surfaces. It may be protected with. The release film is used as a protective material for the pressure-sensitive adhesive layer, and is peeled off when attached to an adherend. Note that the release film is not necessarily provided. As the release film, a commonly used release film can be used, and is not particularly limited. Examples thereof include a plastic film surface-treated with a release agent such as silicone, long-chain alkyl, or fluorine. The release film can be formed by a known method. Also, the thickness of the release film is not particularly limited, and the thicknesses of the two release films may be the same or different. Also, different types of release films may be used, and the releasability can be controlled by changing the rigidity.

(Optical adhesive sheet for fixing resin plates)
An optical pressure-sensitive adhesive sheet (an optical pressure-sensitive adhesive sheet for fixing a resin plate) used for fixing a transparent resin plate of the present invention is an optical pressure-sensitive adhesive sheet obtained by curing the above-described composition for a photocurable transparent pressure-sensitive adhesive sheet. It is. Optical adhesive sheet for fixing transparent resin plates can be used for fixing (meth) acrylic resin, polycarbonate resin, polyethylene terephthalate resin, etc. used in protective panels such as image display devices and touch panels. The foam resistance at the bottom can be suppressed. Therefore, the laminated body which adhere | attached the transparent resin plate fixing optical adhesive sheet with the transparent resin plate can be used suitably as a touch panel.

(Transparent adhesive sheet for fixing transparent conductive film)
The optical pressure-sensitive adhesive sheet (transparent conductive film-fixing pressure-sensitive adhesive sheet) used for fixing the transparent conductive film in the present invention is an optical pressure-sensitive adhesive sheet obtained by curing the above-described composition for a photocurable transparent pressure-sensitive adhesive sheet. . The pressure-sensitive adhesive sheet for fixing a transparent conductive film can be suitably bonded to the conductive layer surface of the transparent conductive film, and the conductive layer is hardly corroded. Therefore, a laminate in which the transparent conductive film fixing sheet is bonded to the conductive layer surface of the transparent conductive film can be suitably used as a touch panel. Moreover, the sheet for fixing a transparent conductive film of the present invention may have a base material or a double-sided pressure-sensitive adhesive sheet having only a pressure-sensitive adhesive layer without having a base material. Moreover, even if the adhesive layer consists of a single layer, multiple layers may be laminated | stacked. Especially, it is preferable that it is a double-sided adhesive sheet which does not have a base material but consists only of an adhesive layer from a viewpoint of ensuring transparency and shape followability. The transparent conductive film used for the transparent conductive film fixing pressure-sensitive adhesive sheet of the present invention is not limited as long as it has a conductive layer on at least one surface layer, and the conductive material is provided on the surface layer of the transparent substrate by vapor deposition or coating. Transparent conductive film. The conductive material deposited or coated in the conductive layer of the transparent conductive film is not particularly limited, and specific examples include indium tin oxide, indium oxide, tin oxide, zinc oxide, cadmium oxide, gallium oxide, and titanium oxide. It is done. Of these, indium tin oxide having excellent transparency and conductivity is preferably used. In the transparent conductive film, the substrate on which the conductive material is deposited or coated is not particularly limited, and examples thereof include glass and resin films.

  The optical pressure-sensitive adhesive sheet of the present invention is particularly preferably used for bonding members constituting the touch panel and the image display device. Examples of the image display device include a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), and electronic paper.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

<(Meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound (A-1)>
A four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube was mixed with 15 mol of isophorone diisocyanate and hydroxyl-terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: GI-3000, hydroxyl value 25 mgKOH / 14 moles of g) were charged and reacted at 60 ° C. for 4 hours to obtain isocyanate group-terminated hydrogenated polybutadiene. This was charged with 2 mol of 2-hydroxyethyl acrylate, heated to 70 ° C. and reacted for 2 hours. After confirming that the isocyanate group had disappeared by IR measurement, the reaction was terminated and the (meth) acryloyl group contained Hydrogenated 1,2-polybutadiene compound (A-1) (weight average molecular weight 70,000) was obtained.

<(Meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound (A-2)>
A four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube was charged with 14 mol of isophorone diisocyanate and a hydroxyl-terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: GI-3000, hydroxyl value 25 mgKOH / g) was charged at 15 mol and reacted at 60 ° C. When the residual isocyanate group became 0.1% or less, 2 mol of 2-isocyanatoethyl acrylate was charged, heated to 70 ° C. and reacted for 2 hours. After confirming the disappearance of the isocyanate group by IR measurement, the reaction was terminated to obtain a (meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound (A-2) (weight average molecular weight 70,000). .

<(Meth) acryloyl group-containing hydrogenated polyisoprene compound (A-3)>
A four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube was charged with 14 mol of isophorone diisocyanate and hydroxyl-terminated hydrogenated polyisoprene (manufactured by Idemitsu Kosan Co., Ltd., product name: Epaul, hydroxyl value 40 mgKOH / g). ) Was charged and reacted at 60 ° C. for 4 hours to obtain isocyanate group-terminated hydrogenated polyisoprene. This was charged with 2 mol of 2-hydroxyethyl acrylate, heated to 70 ° C. and reacted for 2 hours. After confirming that the isocyanate group had disappeared by IR measurement, the reaction was terminated and the (meth) acryloyl group contained A hydrogenated polyisoprene compound (A-3) (weight average molecular weight 80,000) was obtained.

<(Meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound (A-4)>
A four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube was charged with 2 mol of isophorone diisocyanate and hydroxyl-terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: GI-3000, hydroxyl value 25 mgKOH / 1 g of g) was charged and reacted at 60 ° C. for 4 hours to obtain isocyanate group-terminated hydrogenated polybutadiene. This was charged with 2 mol of 2-hydroxyethyl acrylate, heated to 70 ° C. and reacted for 2 hours. After confirming that the isocyanate group had disappeared by IR measurement, the reaction was terminated, and (meth) acryloyl group-containing hydrogen was added. An added 1,2-polybutadiene compound (A-4) (weight average molecular weight 7,000) was obtained.

<(Meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound (A-5)>
A four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube was charged with 31 mol of isophorone diisocyanate and hydroxyl-terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: GI-3000, hydroxyl value 25 mgKOH / 29 moles of g) were charged and reacted at 60 ° C. for 4 hours to obtain isocyanate group-terminated hydrogenated polybutadiene. This was charged with 2 mol of 2-hydroxyethyl acrylate, and the reaction was carried out by raising the temperature to 70 ° C., but it became high molecular weight and gelled during the reaction.

Examples 1-7, Comparative Examples 1-10
Each of the compositions shown in Table 1 and Table 2 was blended and mixed with a disper at room temperature to prepare a uniform photocurable transparent adhesive sheet composition. The prepared composition for a photocurable transparent adhesive sheet is applied to a release PET film (100 mm × 100 mm × 100 μm) using an applicator so that the film thickness is 200 μm, and the upper surface is a release PET film having a thickness of 25 μm. After covering, using an ultraviolet irradiation device (UV irradiation device 4 kw × 1, manufactured by Nippon Battery Co., Ltd., output: 160 W / cm, metal halide lamp), an irradiation distance of 12 cm, a lamp moving speed of 20 m / min, and an irradiation amount of about 1000 mJ / cm ² The pressure-sensitive adhesive sheet having a thickness of about 200 μm sandwiched between the release PET films was obtained by irradiating with ultraviolet rays and curing under the above conditions.

(Calculation of theoretical glass transition temperature)
About the Example and the comparative example, the theoretical glass transition temperature of the polymer which consists of the (B) hydroxyl group-containing (meth) acrylate ester and the polymerizable monomer (C) used was calculated from the above formula (1). . The results are shown in Tables 1 and 2.

(Measurement of electrical resistance of indium tin oxide film)
The adhesive sheet obtained above is cut into a size of 50 mm × 50 mm, the release PET film having a thickness of 25 μm is peeled off, and bonded to the indium tin oxide film surface of the 100 mm × 100 mm indium tin oxide-deposited PET film. The electrical resistance value measuring device, “Lorestar GP” manufactured by Mitsubishi Chemical Corporation, was used at both ends of the bonded adhesive sheet, and the initial electrical resistance value (R ₁ ) was measured. The indium tin oxide-deposited PET film to which the adhesive sheet is bonded is allowed to stand for 500 hours at 60 ° C. and 90% RH, and left for 1 hour under conditions of 23 ° C. and 50% RH. The value (R ₂ ) was measured. The increase rate of the electric resistance value of the indium tin oxide film was calculated by the following formula (3).

The rate of increase in electrical resistance value was evaluated according to the following criteria. The results are shown in Tables 1 and 2.
○: Electrical resistance value increase rate of less than 5% Δ; Electrical resistance value increase rate of less than 5 to 10% ×: Electrical resistance value increase rate of 10% or more

(Measurement of adhesive strength of adhesive sheet)
The pressure-sensitive adhesive sheet obtained above was cut into a size of 25 mm × 100 mm, and the 25 μm-thick release PET film of the release PET film existing on both sides of the pressure-sensitive adhesive sheet was peeled off, and then a 50 μm-thick PET film ( Toray Industries, Inc., “Lumirror S-10”) was backed (pasted) to create a strip-shaped sheet piece. Next, after peeling off the 100 μm-thick release PET film on one side of the above strip-shaped sheet, the adhesive surface (measurement surface) was attached to the test plate by reciprocating a 2 kg rubber roller (width: about 50 mm) once. A measurement sample was prepared. A glass plate was used as a test plate. The obtained measurement sample is left for 24 hours in an environment of 23 ° C. and 50% humidity, and subjected to a tensile test in the 180 ° direction at a peeling rate of 300 mm / min in accordance with JIS Z0237, to the glass sheet of the pressure-sensitive adhesive sheet. The adhesive strength (N / 25 mm) was measured. The obtained measured value was defined as adhesive strength. The results are shown in Tables 1 and 2.

(Total light transmittance measurement)
The pressure-sensitive adhesive sheet obtained above was cut into a size of 30 mm × 30 mm, and the release PET film having a thickness of 25 μm was peeled off from the release PET film existing on both sides of the pressure-sensitive adhesive sheet, and then bonded to a glass plate for measurement. A sample was used. About the sample for a measurement, the total light transmittance (%) was measured using "HR-100 type" by Murakami Color Research Laboratory. The results are shown in Tables 1 and 2.

(Foam peeling property)
With an easy-adhesive surface of a 100 mm × 100 mm optical PET film (Toyobo Co., Ltd., Cosmo Shine A4100) and a 1 mm thick polycarbonate plate (Mitsubishi Gas Chemical Co., Ltd., Iupilon sheet MR-58) After pasting together with the obtained pressure-sensitive adhesive sheet, a sample subjected to defoaming treatment at 40 ° C. and 0.5 MPa for 10 minutes in an autoclave (Sakura Seiki Co., Ltd., TAC-200) was used as a measurement sample. This was allowed to stand for 500 hours under conditions of 60 ° C. and 90% humidity, and the appearance defects such as foaming and peeling at the adhesive layer interface were visually evaluated.

The evaluation of the anti-foaming peeling property was performed according to the following criteria. The results are shown in Tables 1 and 2.
○: No foaming Δ; Foaming with a diameter of less than 1 mm ×: Foaming with a diameter of 1 mm or more

(Whitening resistance)
The pressure-sensitive adhesive sheet obtained above was cut into a size of 30 mm × 30 mm, and the release PET film having a thickness of 25 μm was peeled off from the release PET film existing on both sides of the pressure-sensitive adhesive sheet, and then bonded to a glass plate for measurement. A sample was used. The configuration of the measurement sample is “glass plate / adhesive sheet / release PET film”. The sample was stored in an environment of 60 ° C. and 95% RH for 120 hours, and the appearance of the sample immediately after taking out in an environment of 23 ° C. and 50% RH (after 0 hour) was visually confirmed. The case where no white turbidity was observed visually was evaluated as ◯ (good whitening resistance), and the case where white turbidity was observed was evaluated as x (poor whitening resistance).

  As is clear from the results in Tables 1 and 2, the composition for the photocurable transparent adhesive sheet of the present invention obtained in the Examples is higher in electrical resistance value, total light transmittance, It turns out that it is excellent in adhesive force and foaming peeling resistance.

  The composition for a photo-curable transparent adhesive sheet of the present invention is for fixing a transparent conductive film because it is excellent in high transparency, adhesiveness, metal corrosion prevention, anti-foaming peeling property in high temperature and high humidity environment, and whitening resistance. It is useful as an adhesive sheet and is suitably used for fixing a transparent resin plate and a transparent conductive film used for a capacitive touch panel.

Claims (11)

(A) A compound having a hydrogenated 1,2-polybutadiene polyol or a hydrogenated polyisoprene polyol and a polyfunctional isocyanate compound, and remaining hydroxyl group or isocyanate group, (meth) acryloyl group, and isocyanate group or hydroxyl group. (Meth) acryloyl group-containing hydrogenated 1,2-polybutadiene compound or (meth) acryloyl group-containing hydrogenated polyisoprene compound having a weight average molecular weight of 50,000 to 200,000 obtained by reaction is 25 to 45% by mass, (B ) 8-20% by mass of (meth) acrylic acid ester having hydroxyl group, (C) 20-61.8% by mass of polymerizable monomer other than (meth) acrylic acid ester having hydroxyl group, (D) Photopolymerization Initiator 0.2-5 mass%, and (E) alicyclic whose softening point is 90-150 degreeC Photocurable transparent adhesive sheet composition containing 5 to 20 wt% wear imparting resin. The composition for photocurable transparent pressure-sensitive adhesive sheets according to claim 1, wherein the acid value is 0 to 5 mgKOH / g. (E) The weight average molecular weight of alicyclic tackifying resin is 500-1500, The composition for photocurable transparent adhesive sheets in any one of Claim 1 or 2. Theoretical glass transition temperature of a copolymer obtained by copolymerizing (B) a hydroxyl group-containing (meth) acrylate ester and (C) a polymerizable monomer other than a hydroxyl group-containing (meth) acrylate ester The composition for a photocurable transparent adhesive sheet according to any one of claims 1 to 3, wherein the temperature is 0C to 50C. The compound having a (meth) acryloyl group and an isocyanate group or a hydroxyl group is a hydroxyalkyl (meth) acrylate or an isocyanate group-containing (meth) acrylate. 5. The photocurable transparent adhesive sheet according to any one of claims 1 to 4. Composition. The composition for a photocurable transparent adhesive sheet according to any one of claims 1 to 5, wherein the polyfunctional isocyanate compound is a hydrogenated diphenylmethane diisocyanate or isophorone diisocyanate. The optical adhesive sheet obtained by hardening | curing the composition for photocurable transparent adhesive sheets in any one of Claims 1-6. The optical pressure-sensitive adhesive sheet according to claim 7, which is used for fixing a transparent resin plate. The optical pressure-sensitive adhesive sheet according to claim 7, which is used for fixing a transparent conductive film. A touch panel using the optical pressure-sensitive adhesive sheet according to claim 7. An image display device using the optical pressure-sensitive adhesive sheet according to claim 7.