JP5701892B2 - Composition for photocurable transparent adhesive sheet - Google Patents

Description

  The present invention is characterized in that a photocurable transparent adhesive sheet obtained by curing a composition for a photocurable transparent adhesive sheet and a composition for a photocurable transparent adhesive sheet is used for laminating a transparent conductive film. A transparent adhesive sheet for fixing a transparent conductive film, a transparent adhesive sheet for fixing a transparent conductive film, and a transparent adhesive sheet for fixing a transparent conductive film obtained by curing a composition for transparent adhesive sheet for fixing a transparent conductive film are transparent. The present invention relates to a laminate that is bonded to a conductive layer surface of a conductive film.

  In recent years, touch panels have begun to be mounted in fields such as mobile phones and game machines. The touch panel is a transparent base material for transparent optical substrates such as ITO (Indium Tin Oxide) and a transparent substrate, glass and a transparent protective sheet for protecting it, and a display device such as a liquid crystal display. It is the laminated body bonded together using the sheet | seat.

  There are two types of touch panels: a resistance film type touch panel that detects mainly by 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 the transparent conductive film is fixed so as to be in contact with the pressure-sensitive adhesive layer surface of the pressure-sensitive 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 metal corrosion prevention properties, a pressure-sensitive adhesive sheet containing a metal corrosion inhibitor (for example, Patent Document 1) has been proposed. Moreover, the adhesive sheet (for example, patent document 2) which reduced the corrosivity with respect to a transparent conductive film by containing a specific amount of nitrogen atom containing components 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.

  On the other hand, a touch panel or the like includes a member having a step such as a printing step, and a touch panel having a member provided with a frame-like printing portion in a mobile phone or the like. In such an application, the pressure-sensitive adhesive sheet is required to have the ability to fill a printing step at the same time as the ability to stick and fix a member, that is, excellent step absorbability. If the transparent adhesive sheet cannot absorb the level difference, the transparent adhesive sheet floats (bubbles or voids) around the edge of the printed layer, and light reflection loss occurs due to the float (bubbles or voids), resulting in a liquid crystal display. There is a risk that the visibility of.

  In order to obtain excellent level difference absorbability, it is advantageous that the transparent pressure-sensitive adhesive sheet is soft and has high adhesive strength. However, for the reasons described above, it is required to have high adhesion without containing an acid component. . In response to this requirement, a pressure-sensitive adhesive composition composed of an acrylic polymer having a specific molecular weight not containing an acid component mainly composed of alkoxyalkyl acrylate and a crosslinking agent can achieve both good adhesion and metal corrosion prevention. Giving a transparent adhesive sheet (for example, Patent Document 3) is disclosed.

  However, a composition obtained by adding a cross-linking agent to a polymer is not sufficiently stable after being liquefied, and it is necessary to dilute the solvent when the polymer is applied. Therefore, a thick adhesive sheet of 100 μm or more is produced. There is a problem that is very difficult.

JP 2006-45315 A JP 2010-144002 A JP 2009-079203 A1

  The problem to be solved by the present invention is that the transparent adhesive sheet obtained by curing does not corrode the conductive layer even if it is directly bonded to the conductive layer surface of the transparent conductive film, and the cohesive force and transparency of the adhesive layer An object of the present invention is to provide a one-pack type photocurable transparent adhesive sheet composition having excellent punching workability and excellent step absorbability. Furthermore, it is in providing this transparent adhesive sheet.

  As a result of intensive studies against the above-mentioned problems of the photocurable transparent adhesive sheet for touch panel, the present inventors have introduced a high molecular weight and a specific amount of (meth) acrylic groups. Photocurability comprising a polyolefin urethane acrylate compound, a (meth) acrylic acid ester having a hydroxyl group, a photopolymerizable monomer having a carboxyl group-containing monomer content of less than a predetermined amount, and a photopolymerization initiator. The composition for a transparent adhesive sheet has the transparency of the photocurable transparent adhesive sheet obtained by curing the composition for the photocurable transparent adhesive sheet, the adhesiveness, the metal corrosion prevention property of the transparent conductive film, and the step absorbency. The present invention was found to be satisfactory, and the present invention was completed based on this finding.

  This invention is shown by (1)-(7) below.

  (1) (A) (meth) acrylic group-containing polyolefin compound having a weight average molecular weight of 10,000 to 300,000, (B) (meth) acrylic acid ester having hydroxyl group, (C) having (meth) hydroxyl group A photocurable transparent pressure-sensitive adhesive sheet composition comprising a photopolymerizable monomer other than an acrylate ester and (D) a photopolymerization initiator, wherein (A) the weight average molecular weight is 10,000 to 300,000. The (meth) acryl group-containing polyolefin compound is a reaction between a polyolefin polyol and a polyfunctional isocyanate compound, and then a compound having 50 to 80 mol% of a (meth) acryl group is reacted with the remaining hydroxyl group or isocyanate group. It is a urethane (meth) acrylate compound obtained by introducing a (meth) acryl group into the molecule, and (C) The carboxyl group-containing monomer contained in the photopolymerizable monomer other than the (meth) acrylic acid ester having a roxyl group is (C) a photopolymerizable monomer other than the (meth) acrylic acid ester having a hydroxyl group. The composition for photocurable transparent adhesive sheets characterized by being 0.1 mass% or less with respect to the whole quantity.

  (2) 10-50 mass% of (meth) acryl group containing polyolefin compound whose weight average molecular weight is 10,000-300,000 with respect to whole quantity of the composition for photocurable transparent adhesive sheets, (B) hydroxyl (Meth) acrylic acid ester having 1 to 30% by weight group, (C) 20 to 88% by weight photopolymerizable monomer other than (meth) acrylic acid ester having a hydroxyl group, and (D) a photopolymerization initiator. It contains 0.2-5 mass%, The composition for photocurable transparent adhesive sheets as described in (1) characterized by the above-mentioned.

  (3) The light as described in (1) or (2), wherein the photopolymerizable monomer other than (C) a hydroxyl group-containing (meth) acrylic acid ester does not contain a carboxyl group-containing monomer. A composition for a curable transparent adhesive sheet.

  (4) The theoretical glass transition temperature of a polymer comprising (B) a (meth) acrylic acid ester having a hydroxyl group and (C) a photopolymerizable monomer other than the (meth) acrylic acid ester having a hydroxyl group is 0 ° C. It is -50 degreeC, The composition for photocurable transparent adhesive sheets in any one of (1)-(3) characterized by the above-mentioned.

  (5) A photocurable transparent adhesive sheet obtained by curing the composition for a photocurable transparent adhesive sheet according to any one of (1) to (4) is used for laminating a transparent conductive film. A transparent adhesive sheet composition for fixing a transparent conductive film, which is characterized.

  (6) A transparent adhesive sheet for fixing a transparent conductive film obtained by curing the composition for transparent adhesive sheet for fixing a transparent conductive film according to (5).

  (7) A laminate, wherein the transparent conductive sheet fixing transparent adhesive sheet according to (6) is adhered to the conductive layer surface of the transparent conductive film.

  The composition for a photocurable transparent adhesive sheet of the present invention contains a high molecular weight (meth) acrylic group-containing polyolefin compound in which the amount of (meth) acrylic group is adjusted in the composition. Furthermore, since the content of the carboxyl group in the composition is not more than a predetermined amount, corrosion of the conductive layer surface of the transparent conductive film due to the acid component can be suppressed, and further, a (meth) acryl having a hydroxyl group in the composition By containing the acid ester, high cohesive force and adhesion to the substrate can be obtained.

  Hereinafter, the present invention will be described in detail.

(Photocurable transparent adhesive sheet composition)
The composition for photocurable transparent adhesive sheets of the present invention comprises (A) a (meth) acrylic group-containing polyolefin compound having a weight average molecular weight of 10,000 to 300,000, and (B) a (meth) acrylic acid ester having a hydroxyl group. (C) A photopolymerizable monomer other than (meth) acrylic acid ester having a hydroxyl group, and (D) a photopolymerization initiator.

((A) (Meth) acrylic group-containing polyolefin compound)
As the (A) (meth) acryl group-containing polyolefin compound, any polyolefin compound having a polyolefin skeleton and having a (meth) acryl group introduced therein can be used. Examples of the polyolefin skeleton that can be used in the (A) (meth) acrylic group-containing polyolefin compound include skeletons such as polyethylene, polypropylene, ethylene / propylene copolymer, butadiene, isoprene, hydrogenated polybutadiene, hydrogenated polyisoprene, and cycloolefin. It is done. Hydrogenated polybutadiene and hydrogenated polyisoprene skeleton are preferable in terms of light resistance, transparency (non-crystalline), and workability (liquid). The (meth) acryl group means CH ₂ ═CH—CO— or CH ₂ ═C (CH ₃ ) —CO—.

  The (A) (meth) acryl group-containing polyolefin compound of the present invention is obtained by introducing a (meth) acryl group into a molecule by urethanizing a (meth) acrylate having a hydroxyl group or an isocyanate group ( A (meth) acryl group-containing polyolefin compound is preferred from the viewpoints of adhesiveness and toughness. (A) As a synthesis method of the (meth) acryl group-containing polyolefin compound, the following two-step reaction can be exemplified.

  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 (hereinafter, also referred to as “polyfunctional isocyanate compound”) with respect to the polyolefin polyol is used in a proportion in which the isocyanate group equivalent is greater than the hydroxyl group equivalent. By reacting, a urethane prepolymer having an isocyanate group is synthesized. At this time, the molecular weight can be adjusted by adjusting the ratio of the hydroxyl group equivalent of the polyolefin polyol and the isocyanate group equivalent of the polyfunctional isocyanate compound. The greater the ratio of the hydroxyl group equivalent to the isocyanate group, the greater the molecular weight of the resulting polyurethane compound, and the smaller the ratio of the hydroxyl group equivalent to the isocyanate group equivalent, 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 ( A (meth) acrylate group-containing polyolefin compound is obtained by reacting (meth) acrylate) and converting the remaining isocyanate group to a (meth) acryl group. 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) acryl 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 a polyolefin polyol at a ratio in which the hydroxyl group equivalent is larger than the isocyanate group equivalent to synthesize a polyurethane compound having a hydroxyl group with an extended chain length. At this time, the molecular weight can be adjusted by adjusting the ratio of the hydroxyl group equivalent of the polyolefin polyol and the isocyanate group equivalent of the polyfunctional isocyanate compound. The larger the ratio of the hydroxyl group equivalent to the isocyanate group, the smaller the molecular weight of the resulting polyurethane compound, and the smaller the ratio of the hydroxyl group equivalent to the isocyanate group equivalent, the greater 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) acrylic 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) acryl 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 continuously 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.

  Examples of the polyfunctional isocyanate compound used in the present invention include tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, and hydrogenated products thereof. A diisocyanate compound is mentioned. Of these, isophorone diisocyanate is preferable 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. When the isocyanate group equivalent is reacted at a ratio higher than the hydroxyl group equivalent, the amount of the polyfunctional isocyanate compound used is preferably 1.8 to 2.2 mol with respect to 1 mol of the polyolefin polyol. More preferably, it is 2.1 mol. More preferably, it is 1.95 to 2.05 mol. When the amount of the polyfunctional isocyanate compound used is less than 1.8 mol, the molecular weight of the resulting (A) (meth) acrylic group-containing polyolefin compound becomes too high, making it difficult to handle, and the amount of polyfunctional isocyanate compound used is 2 When the amount exceeds 2 mol, the molecular weight of the resulting (A) (meth) acrylic group-containing polyolefin compound becomes too low, and the strength of the pressure-sensitive adhesive sheet tends to be insufficient. In the case where the hydroxyl group equivalent is reacted at a ratio higher than the isocyanate group equivalent, the amount of the polyfunctional isocyanate compound used is preferably 0.4 to 0.6 mol per 1 mol of the polyolefin polyol, 0.45 to More preferably, it is 0.55 mol. More preferably, it is 0.48-0.52 mol. If the amount of the polyfunctional isocyanate compound used is less than 0.4 mol, the molecular weight of the resulting (A) (meth) acrylic group-containing polyolefin compound becomes too low, so that the strength of the pressure-sensitive adhesive sheet tends not to be sufficiently obtained. If the amount of the polyfunctional isocyanate compound used is more than 0.6 mol, the molecular weight of the resulting (A) (meth) acrylic group-containing polyolefin compound becomes too high, making it difficult to handle.

  The urethane (meth) acrylate compound which is a (meth) acryl group-containing polyolefin compound having a weight average molecular weight of 10,000 to 300,000 according to the present invention is a high molecular weight compound by reacting a polyolefin polyol and a polyfunctional isocyanate compound. Next, 50 to 80 mol% (meth) acrylic groups are introduced with respect to the remaining hydroxyl groups or isocyanate groups. It is more preferable to introduce 55 to 75 mol% (meth) acrylic groups, and it is more preferable to introduce 60 to 70 mol% (meth) acrylic groups with respect to the remaining hydroxyl groups or isocyanate groups. When the ratio of introducing the (meth) acrylic group is less than 50 mol%, there is a polyolefin polyol that cannot introduce the (meth) acrylic group, and the adhesive force may be lowered, which is not preferable. If it is larger than 80 mol%, the resulting pressure-sensitive adhesive sheet may become too hard, which is not preferable.

The molecular weight of the (A) (meth) acryl group-containing polyolefin compound is preferably 10,000 to 300,000, more preferably 20,000 to 200,000, and even more preferably 50,000 to 100,000. is there. The molecular weight can be adjusted by adjusting the amounts of the polyolefin polyol and the polyfunctional isocyanate compound. When the weight average molecular weight is less than 10,000, the cohesive force of the obtained pressure-sensitive adhesive sheet is low, and thus the strength of the pressure-sensitive adhesive sheet may not be sufficient, which is not preferable. On the other hand, when the molecular weight is larger than 300,000, 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. It 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) As content of (meth) acryl group containing polyolefin compound, it is preferable that it is 10-50 mass% in the composition for photocurable transparent adhesive sheets, and it is more preferable that it is 15-45 mass%. More preferably, it is 20-40 mass%. When the content is less than 10% by mass, the resulting pressure-sensitive adhesive sheet becomes brittle, which is not preferable. When the amount is more than 50% by mass, the adhesive strength of the resulting adhesive sheet may be lowered, which is not preferable.

((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, These Specific examples of 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,3-butanediol (meth) acrylate, 1,4-butanediol (Meth) acrylate, 1,6-hexanediol (meth) acrylate, 3-methylpentanediol (meth) acrylate and the like can be exemplified, and they can be used alone or in combination of two or more. Especially, 2-hydroxyethyl acrylate is preferable at the point of the adhesive force of the adhesive sheet obtained. (B) As content of the (meth) acrylic acid ester which has a hydroxyl group, it is preferable to contain 1-30 mass% in the composition for photocurable transparent adhesive sheets, More preferably, it is 5-25 mass%, More preferably, it is 10-20 mass%. If it is less than 1% by mass, the adhesiveness of the obtained pressure-sensitive adhesive sheet to the substrate is insufficient, which is not preferable. Moreover, when more than 30 mass%, the water resistance of an adhesive sheet worsens and is unpreferable.

((C) Photopolymerizable monomer other than (meth) acrylic acid ester having hydroxyl group)
(C) A photopolymerizable monomer other than the (meth) acrylic acid ester having a hydroxyl group (hereinafter sometimes referred to as “(C) photopolymerizable monomer”) is a photopolymerizable monomer. In addition, a monomer other than a (meth) acrylic acid ester having a hydroxyl group and a monomer not containing a carboxyl group (chemical formula: —COOH) is preferable. The monomer is not particularly limited, and monofunctional or polyfunctional photopolymerizable monomers having a vinyl group, a (meth) acryl group, or the like can be used alone or in combination of two or more. Examples of the photopolymerizable 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). ) Acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, n-hexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, etc. Alkyl (meth) acrylate, cyclohexyl (meth) acrylate, norbornyl (meth) acrylate, isobornyl (meth) acrylate, norbornanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopenteni Oxyethyl (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 photopolymerizable monomer (C) of the present invention, from the viewpoints of miscibility with (A) (meth) acrylic group-containing polyolefin compound, adhesive sheet adhesiveness, strength, light resistance, and heat resistance, alkyl (Meth) acrylate or cyclic alkyl (meth) acrylate is preferred. The monofunctional or polyfunctional functional group mentioned here refers to a (meth) acrylic group. The content of the photopolymerizable monomer (C) is preferably 20 to 88% by mass, more preferably 20 to 70% by mass in the photocurable transparent adhesive sheet composition. More preferably, it is 40-69 mass%. If it is less than 20% by mass, the adhesiveness of the obtained pressure-sensitive adhesive sheet to the substrate is insufficient, which is not preferable. Moreover, when more than 88 mass%, since the cohesion force of an adhesive sheet becomes low, an adhesive force becomes low and is unpreferable.

  In the present invention, the carboxyl group-containing monomer such as acrylic acid or methacrylic acid contained in the photopolymerizable monomer (C) is 0.1% relative to the total amount of the photopolymerizable monomer (C). It is less than or equal to mass%, more preferably less than or equal to 0.05 mass%. More preferably, the photopolymerizable monomer (C) does not contain a carboxyl group-containing monomer. When the carboxyl group-containing monomer is more than 0.1% by mass with respect to the total amount of the photopolymerizable monomer (C), it becomes difficult to suppress corrosion of the conductive layer surface of the transparent conductive film.

The theoretical glass transition temperature of the polymer comprising the (B) hydroxyl group-containing (meth) acrylic acid ester of the present invention and the photopolymerizable monomer (C) is 0 to 0 from the viewpoint of the strength and adhesive strength of the pressure-sensitive adhesive sheet. It is preferable that it is 50 degreeC, It is more preferable that it is 5-45 degreeC, It is further more preferable that it is 10-40 degreeC. When the temperature is lower than 0 ° C., the resulting pressure-sensitive adhesive sheet becomes too soft due to the influence of the (A) (meth) acrylic group-containing polyolefin compound, which is not preferable because the adhesive strength of the pressure-sensitive adhesive sheet is lowered. 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 of a monomer not described in the above-mentioned publicly known material, 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, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopro is used from the viewpoint of solubility in the resulting composition for a photocurable transparent adhesive sheet. Pan-1-one is preferred. These (D) photopolymerization initiators are used alone or in combination of two or more.

  (D) Content of a photoinitiator shall be 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. It is preferably 0.5 to 3% by mass. (D) When the content of the photopolymerization initiator is less than 0.2% by mass, the photocuring tends to be insufficient, and when it exceeds 5% by mass, the adhesiveness of the obtained pressure-sensitive adhesive sheet tends to decrease. There is not preferable.

  The composition for a photocurable transparent adhesive sheet of the present invention is preferably (A) component 10 to 50% by mass and (B) component 1 to 30% relative to the total amount of the photocurable transparent adhesive sheet composition. %, (C) component 20-88 mass%, and (D) component 0.2-5 mass%. And more preferably, (A) component 15-45 mass%, (B) component 5-25 mass%, and (C) component 20-70 mass% with respect to the whole quantity of the composition for photocurable transparent adhesive sheets. And (D) component 0.2 to 5% by mass. And more preferably, (A) component 20-40 mass%, (B) component 10-20 mass%, (C) component 40-69 mass% with respect to the whole quantity of the composition for photocurable transparent adhesive sheets. And (D) component 0.5-3 mass% is contained.

  In order to improve the adhesive force of the resulting pressure-sensitive adhesive sheet, a tackifier resin may be added to the composition for the photocurable transparent pressure-sensitive adhesive sheet of the present invention as long as the transparency is not lowered. Examples of tackifier resins include rosin resins such as rosin and rosin esterified products; terpene resins such as diterpene polymers and α-pinene-phenol copolymers; aliphatic (C5) and aromatic ( Petroleum resin such as C9); styrene resin, phenol resin, xylene resin and the like. From the viewpoint of light resistance, it is preferable to add an esterified product of hydrogenated rosin or disproportionated rosin with few unsaturated double bonds, aliphatic or aromatic petroleum resin, high Tg acrylic resin, or the like to the adhesive sheet. As addition amount of tackifying resin, 100 mass parts of total amount of (A) component, (B) component, (C) component, and (D) component with respect to 100 mass parts of composition for photocurable transparent adhesive sheets 1) to 10 parts by weight are preferably added.

  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.

(Composition for transparent adhesive sheet for fixing transparent conductive film)
The composition for pressure-sensitive adhesive sheets for fixing a transparent conductive film of the present invention is a composition for pressure-sensitive adhesive sheets for fixing a transparent conductive film comprising the above-described composition for a photocurable transparent pressure-sensitive adhesive sheet.

  As the transparent conductive film in which the composition for fixing a transparent conductive film of the present invention is used, any conductive layer may be used as long as it has a conductive layer on at least one surface layer. The transparent conductive film provided by (1) is mentioned. 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.

(Transparent adhesive sheet for fixing transparent conductive film)
The transparent pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention is a transparent pressure-sensitive adhesive sheet for fixing a transparent conductive film obtained by curing the above-described composition for fixing a transparent conductive film. It can be suitably bonded and the conductive layer is unlikely to corrode. Therefore, the laminated body which adhere | attached the transparent adhesive sheet for transparent conductive film adhesion with the conductive layer surface of a transparent conductive film can be used suitably as a touch panel. Further, the transparent adhesive sheet for fixing a transparent conductive film of the present invention may have a base material, or may be 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 adhesive sheet for fixing a transparent conductive film of the present invention is obtained by applying a transparent adhesive sheet composition for fixing a transparent conductive film to a release PET film, and irradiating the applied composition with ultraviolet rays using an ultraviolet irradiation device or the like. It can be obtained by photocuring. The thickness of the transparent conductive film fixing adhesive sheet is preferably 5 to 500 μm, more preferably 10 to 300 μm. When the film thickness of the adhesive sheet for fixing a transparent conductive film becomes thinner than 5 μm, it becomes difficult to bond the adhesive sheet, and when it becomes thicker than 500 μm, it tends to be difficult to control the film thickness.

  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) acrylic group-containing polyolefin 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 charged with 2 moles 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 1.4 mol of 2-hydroxyethyl acrylate (70 mol% with respect to the remaining isocyanate groups) and 0.6 mol of isobutanol, heated to 70 ° C. and reacted for 2 hours. After confirming disappearance, the reaction was terminated, and a (meth) acryl group-containing polyolefin compound (A-1) (weight average molecular weight 50,000) was obtained.

<(Meth) acrylic group-containing polyolefin 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 1 mol of isophorone diisocyanate and hydroxyl-terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: GI-3000, hydroxyl value 25 mgKOH / 2) g) was charged and reacted at 60 ° C. When the residual isocyanate group became 0.1% or less, 1.4 mol of 2-isocyanatoethyl acrylate (70 mol% with respect to the residual hydroxyl group) was charged. The temperature was raised to 0 ° C. and reacted for 2 hours. After confirming that the isocyanate group had disappeared by IR measurement, the reaction was terminated, and the (meth) acryl group-containing polyolefin compound (A-2) (weight average molecular weight 50, 000).

<(Meth) acrylic group-containing polyolefin 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 2 moles 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 2.0 mol of 2-hydroxyethyl acrylate (100 mol% with respect to the remaining isocyanate group), heated to 70 ° C., reacted for 2 hours, and confirmed that the isocyanate group disappeared by IR measurement. The reaction was terminated to obtain a (meth) acryl group-containing polyolefin compound (A-3) (weight average molecular weight 50,000).

<(Meth) acrylic group-containing polyolefin 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 moles 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 0.4 mol of 2-hydroxyethyl acrylate (20 mol% with respect to the remaining isocyanate groups) and 1.6 mol of isobutanol, heated to 70 ° C., reacted for 2 hours, and the isocyanate groups disappeared by IR measurement. After confirming that the reaction was completed, the reaction was terminated to obtain a (meth) acryl group-containing polyolefin compound (A-4) (weight average molecular weight 50,000).

<(Meth) acrylic group-containing polyolefin 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 mixed with 1.4 mol of 2-isocyanatoethyl acrylate and hydroxyl-terminated hydrogenated polybutadiene (product name: GI-, manufactured by Nippon Soda Co., Ltd.). 1000, hydroxyl value 75 mgKOH / g) was charged at 1 mol and reacted at 60 ° C. for 4 hours. After confirming that the isocyanate group had disappeared by IR measurement, the reaction was terminated, and the (meth) acryl group-containing polyolefin compound (A -5) (weight average molecular weight 5,000) was obtained.

<(Meth) acrylic group-containing polyolefin compound (A-6)>
A four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube, 1.5 mol of isophorone diisocyanate and a hydroxyl-terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: GI-3000, hydroxyl value) 25 mg KOH / g) was charged at 1 mol and reacted at 60 ° C. for 4 hours to obtain an isocyanate group-terminated hydrogenated polybutadiene. To this, 0.8 mol of 2-hydroxyethyl acrylate (80 mol% with respect to the remaining isocyanate group) and 0.2 mol of isobutanol were charged and the temperature was raised to 70 ° C. to carry out the reaction. Gelled.

Examples 1-6, Comparative Examples 1-4
Each of the compositions shown in Table 1 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 500 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) acrylic acid ester and the photopolymerizable monomer (C) used was calculated from the above formula (1). did. The results are shown in Table 1.

(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 was bonded was left at 90 ° C. for 500 hours and left at 23 ° C. and 50% RH for 1 hour. The resistance 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 (2).

The rate of increase in electrical resistance value was evaluated according to the following criteria. The results are shown in Table 1.
○: 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 to a size of 25 × 100 mm, and after removing the 100 μm-thick release PET film from the release PET film existing on both sides of the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive surface (measurement surface) was tested. A 2 kg rubber roller (width: about 50 mm) was attached to the plate by reciprocating once to prepare a measurement sample. 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 Table 1.

(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 Table 1.

(Step absorbency)
A PET film (thickness: 25 μm) was bonded to the pressure-sensitive adhesive sheet obtained above to produce a step tape having a total thickness of 225 μm. The step tape was attached in a frame shape to the periphery along the four sides of the main surface of the rectangular glass plate to make a stepped glass plate. An adhesive sheet was attached to the entire surface of the stepped glass plate to which the step tape was attached, and the floating of the adhesive layer at the step portion was visually observed.

The level difference absorbability was evaluated according to the following criteria. The results are shown in Table 1.
○: Pass when the adhesion layer is not lifted at the stepped part ×: Fail when the lift is confirmed

  As is clear from the results in Table 1, the composition for a photocurable transparent adhesive sheet of the present invention obtained in the Examples has an increase in electrical resistance value, total light transmittance, adhesive strength, as compared with the Comparative Example. It can be seen that the step absorbability is excellent.

  The composition for a photocurable transparent pressure-sensitive adhesive sheet of the present invention is useful as a pressure-sensitive adhesive sheet for fixing a transparent conductive film because it is excellent in high transparency, metal corrosion prevention, step absorbency, and pressure-sensitive adhesiveness. This is useful for fixing a transparent conductive film used in a touch panel of the type.

Claims (7)

(A) (meth) acrylic group-containing polyolefin compound having a weight average molecular weight of 10,000 to 300,000, (B) (meth) acrylic acid ester having hydroxyl group, (C) (meth) acrylic acid ester having hydroxyl group A photopolymerizable monomer other than the above and (D) a photocurable transparent adhesive sheet composition comprising a photopolymerization initiator, and (A) has a weight average molecular weight of 10,000 to 300,000 ( The (meth) acryl group-containing polyolefin compound reacts the polyolefin polyol and the polyfunctional isocyanate compound, and then reacts the remaining hydroxyl group or isocyanate group with a compound having 50 to 80 mol% (meth) acryl group, It is a urethane (meth) acrylate compound obtained by introducing a (meth) acryl group into the molecule, and (C) a hydroxy The carboxyl group-containing monomer contained in the photopolymerizable monomer other than the (meth) acrylic acid ester having an alkyl group is (C) a photopolymerizable monomer other than the (meth) acrylic acid ester having a hydroxyl group. The composition for photocurable transparent adhesive sheets characterized by being 0.1 mass% or less with respect to the whole quantity. (A) 10-50 mass% of (meth) acryl group containing polyolefin compound whose weight average molecular weight is 10,000-300,000 with respect to the whole quantity of the composition for photocurable transparent adhesive sheets, (B) It has a hydroxyl group. (Meth) acrylic acid ester 1-30 mass%, (C) 20-88 mass% of photopolymerizable monomers other than (meth) acrylic acid ester having a hydroxyl group, and (D) photopolymerization initiator 0.2. The composition for a photocurable transparent adhesive sheet according to claim 1, comprising ˜5 mass%. (C) The photocurable transparent adhesive sheet according to claim 1 or 2, wherein the photopolymerizable monomer other than the (meth) acrylic acid ester having a hydroxyl group does not contain a carboxyl group-containing monomer. Composition. The theoretical glass transition temperature of a polymer comprising (B) a hydroxyl group-containing (meth) acrylate ester and (C) a photopolymerizable monomer other than a hydroxyl group-containing (meth) acrylate ester is 0 ° C. to 50 ° C. The composition for photocurable transparent pressure-sensitive adhesive sheets according to any one of claims 1 to 3. A photocurable transparent adhesive sheet obtained by curing the composition for a photocurable transparent adhesive sheet according to any one of claims 1 to 4, which is used for laminating a transparent conductive film. A composition for transparent adhesive sheet for film fixation. A transparent adhesive sheet for fixing a transparent conductive film obtained by curing the composition for transparent adhesive sheet for fixing a transparent conductive film according to claim 5. The transparent adhesive sheet for transparent conductive film fixation of Claim 6 is adhere | attached on the conductive layer surface of the transparent conductive film, The laminated body characterized by the above-mentioned.