JP2013256552A - Photopolymerizable adhesive, adhesive sheet, and laminate for touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photopolymerizable adhesive for a touch panel having a conductive film made of a metal or metal oxide, which suppresses whitening or foaming by virtue of its excellent moist heat-resistant stability and antifoaming properties, and free of generation of odor and skin irritancy, further free of corrosivity to a metal or metal oxide; an adhesive sheet; and a laminate for a touch panel using the sheet.SOLUTION: A photopolymerizable adhesive includes (A) 100 pts.wt.of a monomer group comprising components (a-1) to (a-3) shown below: (a-1) 40-92 wt.% of alkyl (meth)acrylate, (a-2) 5-20 wt.% of a hydroxy group-containing monomer, (a-3) 3-25 wt.% of water-soluble N-substituted acrylamide (100% total of monomers), or (A') partially polymerized matter thereof; and (B) 0.01-2 pts.wt. of an isocyanate-based crosslinking agent and/or a multifunctional monomer; and (C) 0.1-2 pts.wt. of a photopolymerization initiator.

Description

  The present invention relates to a photopolymerizable pressure-sensitive adhesive used for a laminate for a touch panel, a pressure-sensitive adhesive sheet in the form of a sheet of the photopolymerizable pressure-sensitive adhesive, and a laminate for a touch panel in which a member is attached using the pressure-sensitive adhesive sheet. .

  At present, the touch panel units mainly used are roughly classified into a resistance film type touch panel and a capacitance type touch panel, both of which are laminates of various materials. System adhesive is used. Since the touch panel unit is disposed on the outermost surface of the screen, the acrylic pressure-sensitive adhesive to be used is required to have high transparency, and further, characteristics such as high heat resistance and moisture heat resistance are required. Specifically, since the touch panel unit, which is a laminate of various materials, is disposed on the outermost surface of the touch panel device, whitening may occur due to the ingress of moisture from the outside. Foaming by entraining and foaming by outgas generated from the material to be laminated are problematic in that appearance defects occur.

  Moreover, in the resistive film type touch panel which has been the mainstream of touch panels so far, various adhesives have been used for attaching polycarbonate (PC) or in-mold film (IMD).

  However, as a characteristic of the PC material, outgas is generated under a high temperature condition, so that foaming occurs under a heat resistant condition and it is difficult to suppress the whitening phenomenon of the pressure-sensitive adhesive layer due to moisture inflow under a wet heat condition. Furthermore, since the IMD has a step of submicron order, there is also a problem that the pressure-sensitive adhesive cannot follow the step and bubbles are involved.

  Conventionally, the above problems have been solved by adding an acid component to the pressure-sensitive adhesive. In other words, the acid component has the function of dispersing the mixed water and preventing it from being deposited, and the water that has entered the pressure-sensitive adhesive layer is dispersed and not precipitated in the pressure-sensitive adhesive layer by the dispersion force of the acid component. The pressure-sensitive adhesive layer was prevented from being whitened and also formed with hydrogen bonds, so the generation of bubbles in heat-resistant foaming was suppressed by the high cohesive force due to the hydrogen bonds.

  Recently, with the enhancement of functions such as multi-touch, capacitive touch panels are becoming the mainstream instead of resistive touch panels. In this capacitive touch panel, the characteristics required for the resistive touch panel are of course necessary, but in addition, because the adhesive is in direct contact with the conductive layer forming the wiring, The property that the adhesive does not change the properties of the conductive layer is required. The conductive layer is formed of a metal or metal oxide such as indium tin oxide (ITO) or antimony tin oxide (ATO), which causes corrosion due to contact with an acid, and its resistance value increases. Means for securing characteristics such as heat resistance and heat-and-moisture resistance using an acid component conventionally used cannot be used.

  Regarding the corrosion of such transparent electrodes made of metals such as ITO and ATO or metal oxides, Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-77287) discloses an alkoxyalkyl acrylate as a main component and a carboxyl group-containing monomer. A polymer obtained by copolymerizing monomers not containing is disclosed, and it is disclosed that the polymer is produced by solution polymerization.

  Thus, by using the alkoxyalkyl acrylate polymer obtained without using the carboxyl group-containing monomer, the corrosion of the transparent electrode made of metal such as ITO or ATO or metal oxide is improved to some extent. In addition, since the alkoxy group has hydrophilicity, the alkoxyalkyl acrylate has an effect of dispersing moisture that has entered the pressure-sensitive adhesive layer and improving wet heat whitening.

  By the way, in recent years, a frame of a display has been printed on a surface support of a touch panel. When the frame-printed surface support and the transparent conductive film are bonded together, it is necessary to fill the step of the printing portion with an adhesive. Therefore, there is a need for a relatively thick adhesive layer that can absorb steps. And in order to manufacture such a thick film adhesive layer, the photopolymerization method with which thick film coating is easy has come to be used. In the photopolymerization method, a pressure-sensitive adhesive layer can be obtained by applying a monomer or a partially polymerized monomer onto a sheet and irradiating the coated surface with light. However, during polymerization (during light irradiation), only a small amount of monomer in the composition is obtained. Volatilizes. Among these, although the above-mentioned alkoxyalkyl acrylate can give good moisture and heat whitening resistance, there are problems of skin irritation and odor, and there is concern about the influence on the operator's body.

JP 2010-77287 A

  The present invention relates to a photopolymerizable pressure-sensitive adhesive for a touch panel having a conductive film made of a metal or a metal oxide, and is excellent in moist heat resistance and foam resistance, thereby suppressing whitening and foaming, and generating odor and skin. An object of the present invention is to provide a photopolymerizable pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and a laminate for a touch panel using the same, which is not irritating and does not corrode metal or metal oxide.

  Another object of the present invention is to provide a photopolymerizable pressure-sensitive adhesive or pressure-sensitive adhesive sheet having good coatability, step following ability and removability.

The present invention relates to the following [1] to [19], for example.
[1] Components (a-1) to (a-3) shown below
(a-1) Alkyl (meth) acrylate 40 to 92% by weight
(a-2) Hydroxyl group-containing monomer 5 to 20% by weight
(a-3) Water-soluble N-substituted acrylamide 3 to 25% by weight
And an isocyanate group crosslinking agent with respect to 100 parts by weight of the monomer group (A) (with 100% by weight of all monomers) or a partially polymerized product (A ′) containing substantially no acidic group-containing monomer A photopolymerizable pressure-sensitive adhesive comprising 0.01 to 2 parts by weight of a polyfunctional monomer (B) and 0.1 to 2 parts by weight of a photopolymerization initiator (C).

  [2] The weight ratio of (a-2) hydroxyl group-containing monomer and (a-3) water-soluble N-substituted acrylamide is (a-2) :( a-3) = 5: 1 to 1: 7. [1] The photopolymerizable pressure-sensitive adhesive according to [1].

  [3] The (a-1) alkyl (meth) acrylate is at least one selected from the group consisting of 2-ethylhexyl (meth) acrylate, butyl acrylate and octyl acrylate [1] or [1] 2].

[4] The photopolymerizable pressure-sensitive adhesive according to any one of [1] to [3], wherein the (a-3) water-soluble N-substituted acrylamide has a cyclic structure.
[5] The photopolymerizable pressure-sensitive adhesive according to [4], wherein (a-3) the water-soluble N-substituted acrylamide is acryloylmorpholine.

[6] The photopolymerizable pressure-sensitive adhesive according to any one of [1] to [5], wherein the monomer group (A) does not contain an alkoxyalkyl (meth) acrylate.
[7] In the pressure-sensitive adhesive, the weight average molecular weight of the polymer in the partial polymer (A ′) of the monomer group (A) is 200,000 to 700,000, [1] to [6] The photopolymerizable pressure-sensitive adhesive according to any one of the above.

  [8] The photopolymerizability according to any one of [1] to [7], wherein the pressure-sensitive adhesive is a pressure-sensitive adhesive for a capacitive touch panel that is in direct contact with a metal or metal oxide. Adhesive.

[9] The photopolymerizable pressure-sensitive adhesive according to [8], wherein the metal oxide is ITO and / or ATO.
[10] A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 10 to 1000 μm formed by irradiating the photopolymerizable pressure-sensitive adhesive described in any one of [1] to [9] with active energy rays.

[11] The pressure-sensitive adhesive sheet according to [10], wherein a cover film subjected to a peeling treatment is disposed on at least one surface of the pressure-sensitive adhesive sheet.
[12] Surface support, pressure-sensitive adhesive layer formed from the photopolymerizable pressure-sensitive adhesive described in any of [1] to [9], metal or metal oxide, metal with support, or with support A laminate for a touch panel in which a transparent conductive film made of a metal oxide is laminated in this order.

[13] The touch panel laminate according to [12], wherein the touch panel laminate is a member forming a capacitive touch panel.
[14] The touch panel laminate according to [12] or [13], wherein frame printing is performed on an edge of a surface of the surface support that faces the pressure-sensitive adhesive layer.

[15] The touch panel laminate as described in [14], wherein the thickness of the frame printing is in the range of 10 to 50 μm.
[16] The metal oxide constituting the transparent conductive film is ITO and / or ATO, and the pressure-sensitive adhesive layer is in direct contact with the transparent conductive film [12] to [15] The laminated body for touchscreens in any one of.

[17] The touch panel laminate according to any one of [12] to [16], wherein the surface support has a thickness in the range of 25 to 2000 μm.
[18] The laminate for a touch panel according to any one of [12] to [17], wherein the transparent conductive film has a thickness in the range of 10 to 100 nm.

  [19] The laminate for a touch panel according to any one of [12] to [18], wherein the pressure-sensitive adhesive layer has a thickness of 10 to 1000 μm.

  Since the photopolymerizable pressure-sensitive adhesive of the present invention does not substantially contain an acid component, it can effectively suppress deterioration due to corrosion of a metal or metal oxide such as silver, ITO, ATO, or tin oxide. it can.

  Since the water-soluble N-substituted acrylamide is used for the photopolymerizable pressure-sensitive adhesive of the present invention, moisture that has penetrated into the photopolymerizable pressure-sensitive adhesive can be dispersed due to its hydrophilicity, and whitening under wet heat can be prevented. In addition, a polymer having water-soluble N-substituted acrylamide as a structural unit has a high glass transition temperature, and therefore has high cohesive force and excellent foam resistance. Furthermore, the water-soluble N-substituted acrylamide has no problems of odor generation and skin irritation.

  In the photopolymerizable pressure-sensitive adhesive of the present invention, the hydroxyl group derived from the hydroxyl group-containing monomer becomes a crosslinking point in the polymer, and a crosslinking structure is formed by the isocyanate-based crosslinking agent to increase the cohesive force. Excellent stability. The photopolymerizable pressure-sensitive adhesive can be easily applied to a thick film. Furthermore, since the obtained pressure-sensitive adhesive sheet is flexible, it has excellent step following ability.

  In general, when an acrylic polymer in which a nitrogen-containing monomer is copolymerized in the pressure-sensitive adhesive layer is used, the adhesive force to the adherend becomes too high. If there is a problem with bonding of members using such an adhesive, if the adhesive layer is peeled to recycle the member that is the adherend, the adherend is peeled off at the time of peeling because of too high adhesive force. There was a risk of damage. The photopolymerizable pressure-sensitive adhesive of the present invention contains water-soluble N-substituted acrylamide and a hydroxyl group-containing monomer in a specific range. By cross-linking this photopolymerizable pressure-sensitive adhesive, a pressure-sensitive adhesive having good removability and easy recycling of the adherend is obtained while exhibiting an appropriate cohesive force.

  Therefore, the photopolymerizable pressure-sensitive adhesive of the present invention, the pressure-sensitive adhesive sheet having this photopolymerizable pressure-sensitive adhesive as a pressure-sensitive adhesive layer, and the laminate for touch panels using this pressure-sensitive adhesive sheet are made of metals such as ITO, ATO, tin oxide, or metals. Corrosion hardly occurs on the transparent conductive film made of an oxide, and there is little variation in the electrical characteristics of the transparent conductive film, and whitening and foaming hardly occur, and no odor is generated. Furthermore, coating property, level difference followability, and removability are good.

FIG. 1 is a cross-sectional view schematically showing an example of a touch panel unit in a resistive film type touch panel incorporating the laminate for a touch panel of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a touch panel unit in a capacitive touch panel incorporating the laminate for a touch panel of the present invention. FIG. 3 is a cross-sectional view schematically showing an example of the configuration of the end of the capacitive touch panel. FIG. 4 is a cross-sectional view schematically showing the adhesive state of the adhesive sheet to the frame print portion formed at the end of the touch panel. FIG. 5 is a cross-sectional view for explaining the state of foaming that occurs in the laminate for a touch panel. FIG. 6 is a cross-sectional view for explaining the occurrence of a whitening phenomenon that occurs in the laminate for a touch panel.

Hereinafter, the present invention will be specifically described.
In this specification, (meth) acrylate refers to acrylate and / or methacrylate.

The photopolymerizable pressure-sensitive adhesive of the present invention is
The following components (a-1) to (a-3)
(a-1) Alkyl (meth) acrylate 40 to 92% by weight
(a-2) Hydroxyl group-containing monomer 5 to 20% by weight
(a-3) Water-soluble N-substituted acrylamide 3 to 25% by weight
And an isocyanate group crosslinking agent with respect to 100 parts by weight of the monomer group (A) (with 100% by weight of all monomers) or a partially polymerized product (A ′) containing substantially no acidic group-containing monomer And / or 0.01 to 2 parts by weight of a polyfunctional monomer (B) and 0.1 to 2 parts by weight of a photopolymerization initiator (C).

[Monomer group (A)]
1. (a-1) Alkyl (meth) acrylate
Examples of (a-1) alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, and n-butyl (meth) acrylate. , Iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl Mention may be made of (meth) acrylate, decyl (meth) acrylate, undeca (meth) acrylate and dideca (meth) acrylate. These (meth) acrylates can be used alone or in combination. Among these, it is preferable to use 2-ethylhexyl acrylate, butyl acrylate, and octyl acrylate from the viewpoint of removability of the photopolymerizable pressure-sensitive adhesive.

  The content of (a-1) alkyl (meth) acrylate in all monomers of the monomer group (A) is 40 to 92% by weight, preferably 50 to 82% by weight, more preferably 60 to 77% by weight. (a-1) When the content of the alkyl (meth) acrylate is more than the above range, the whitening resistance is insufficient, and when it is less than the above range, sufficient adhesive strength may not be obtained.

2. (a-2) Hydroxyl group-containing monomer
In the (a-2) hydroxyl group-containing monomer, at least a part of the hydroxyl group becomes a crosslinking point in the polymer and reacts with the crosslinking agent (B) described later. As a result, the polymer obtained by irradiating the photopolymerizable pressure-sensitive adhesive of the present invention with active energy rays has a crosslinked structure, a high cohesive force is achieved, and foaming is efficiently suppressed.

  (a-2) The hydroxyl group-containing monomer is preferably a (meth) acrylate compound having a hydroxyl group. Examples of such a (meth) acrylate compound having a hydroxyl group include 2-hydroxyethyl (meth) acrylate and 3-hydroxypropyl. Mention may be made of (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 8-hydroxyoctyl (meth) acrylate. . These (meth) acrylate compounds having a hydroxyl group can be used alone or in combination. Among these, as the (meth) acrylate compound, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable.

  The content of the (a-2) hydroxyl group-containing monomer in all monomers of the monomer group (A) is 5 to 20% by weight, preferably 8 to 20% by weight, and more preferably 8 to 15% by weight. (a-2) If the content of the hydroxyl group-containing monomer is more than the above range, the resulting crosslinked structure of the polymer is excessively formed, and the flexibility of the photopolymerizable pressure-sensitive adhesive becomes poor, and it is involved when pasted on the adherend. Foam may be generated and foam resistance may be insufficient. When the amount is less than the above range, the amount of copolymerization of other monomers having no crosslinkable functional group inevitably increases, and the crosslinked structure by the crosslinking agent (B) described later may not be sufficiently formed. For this reason, the cohesive force becomes weak and the foam resistance may be insufficient.

3. (a-3) Water-soluble N-substituted acrylamide
(a-3) A copolymer obtained by copolymerizing a water-soluble N-substituted acrylamide is active in a photopolymerizable pressure-sensitive adhesive by accelerating crosslinking by the component (B) described later in addition to a high glass transition temperature. The cohesive force of the polymer obtained by irradiation with energy rays is increased. In addition, since water-soluble N-substituted acrylamide is water-soluble, it has a high effect of dispersing moisture that has penetrated into the photopolymerizable pressure-sensitive adhesive, and suppresses whitening of the polymer obtained from the photopolymerizable pressure-sensitive adhesive under wet heat. it can. And there is no problem of odor generation and skin irritation. Furthermore, since it is highly polar, it enhances the adhesion of the polymer obtained from the photopolymerizable pressure-sensitive adhesive to the metal surface.

  (a-3) Examples of the water-soluble N-substituted acrylamide include acryloylmorpholine, dimethylacrylamide, diethylacrylamide, isopropylacrylamide, dimethylaminopropylacrylamide and hydroxyethylacrylamide. These water-soluble N-substituted acrylamides can be used alone or in combination. Among these, from the viewpoint of skin irritation, a compound having a cyclic structure is preferable, and acroylmorpholine is more preferable.

  The content of the (a-3) water-soluble N-substituted acrylamide in all monomers of the monomer group (A) is 3 to 25% by weight, preferably 10 to 25% by weight, more preferably 15 to 25% by weight. (a-3) If the content of the water-soluble N-substituted acrylamide is more than the above range, the cross-linked structure is excessively formed, the flexibility of the photopolymerizable pressure-sensitive adhesive becomes poor, and entrainment bubbles are generated at the time of pasting to prevent foaming. May become insufficient. When the amount is less than the above range, the cohesive force of the photopolymerizable pressure-sensitive adhesive becomes weak, and foaming due to outgas from the adherend may not be suppressed. Moreover, the effect which suppresses whitening by the water | moisture content which penetrate | invaded the adhesive cannot fully be acquired.

  The viewpoint that the photopolymerizable pressure-sensitive adhesive forms a crosslinked structure having cohesive strength that satisfies foaming resistance against foaming caused by outgas from the adherend or entrained foam when attached to the adherend, and also ensures removability From the above, the weight ratio of (a-2) hydroxyl group-containing monomer to (a-3) water-soluble N-substituted acrylamide in the photopolymerizable pressure-sensitive adhesive of the present invention is (a-2) :( a-3) = 5. : 1 to 1: 7 is preferable, and 1: 1 to 1: 5 is more preferable.

4). Other monomers included in monomer group (A) In addition to the above, monomers included in monomer group (A) include vinyl acetate; (meth) acrylonitrile; cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenyl ( (Meth) acrylate; styrene, methyl styrene, dimethyl styrene, trimethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, octyl styrene and other alkyl styrene, fluoro styrene, chloro styrene, bromo styrene, dibromo styrene, iodo styrene Styrene monomers such as nitrostyrene, acetylstyrene and methoxystyrene; glycidyl (meth) acrylate and the like can be used as long as the effects of the present invention are not impaired. These can be used alone or in combination.

  The photopolymerizable pressure-sensitive adhesive of the present invention does not substantially contain an acidic group-containing monomer. Here, in this specification, the acidic group does not contain a hydroxyl group. Further, “substantially free of acidic group-containing monomer” means that no monomer having an acidic group is intentionally added during copolymerization, and it is usually 0 in terms of the acid value of the final polymer obtained. .5 mgKOH / g or less.

  Examples of the acidic group-containing monomer include monomers having a carboxyl group such as (meth) acrylic acid, maleic acid, and itaconic acid, monomers having a phosphoric acid group, and monomers having a sulfonic acid group.

  Since the photopolymerizable pressure-sensitive adhesive of the present invention contains substantially no acidic group-containing monomer, the polymer obtained by irradiating the photopolymerizable pressure-sensitive adhesive of the present invention with active energy rays is a metal or a metal oxide. Even if they are in direct contact with the wiring made of these, they are not corroded and the resistance value of the wiring is not changed over a long period of time.

The photopolymerizable pressure-sensitive adhesive of the present invention preferably contains no alkoxyalkyl (meth) acrylate. This is because of skin irritation and odor problems.
[Isocyanate crosslinking agent and / or polyfunctional monomer (B)]
The photopolymerizable pressure-sensitive adhesive of the present invention can be crosslinked with a polymer obtained by irradiation with active energy rays by further blending an isocyanate crosslinking agent and / or a polyfunctional monomer (B). As a result, the cohesive force of the crosslinked polymer is improved, and even if air bubbles are slightly involved at the time of pasting, expansion of the air bubbles can be suppressed, and excellent heat-resistant foaming properties are exhibited.

  Examples of the isocyanate-based crosslinking agent include two or more isocyanate groups in a molecule such as tolylene diisocyanate, xylylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, and hydrogenated diphenylmethane diisocyanate. Compounds having these: compounds obtained by addition reaction with polyhydric alcohols such as trimethylolpropane and pentaerythritol, their isocyanurate compounds and burette type compounds, as well as known polyether polyols, polyester polyols, acrylic polyols, Two or more urethane prepolymers that have undergone addition reaction with polybutadiene polyol and polyisoprene in the molecule It can be exemplified compounds having an isocyanate group.

  Among these, xylylene diisocyanate and its trimethylolpropane adduct, and hexaxylene diisocyanate, and the hexamethylolpropane adduct can be improved in that the compatibility with the adherend can be improved, the entrainment of bubbles during bonding can be reduced, and the outgassing at high temperatures can be suppressed. An isocyanurate compound of methylene diisocyanate is preferable, and hexamethylene diisocyanate and its trimethylolpropane adduct are preferable from the viewpoint that heat-resistant foaming properties can be improved.

  Examples of polyfunctional monomers include ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,4-butanediol di ( (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, hydrogenated diclopentadienyl di (meth) acrylate, ethylene oxide modified bisphenol A di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol Tetra (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, pentaerythritol hexa (meth) acrylate, polyfunctional epoxy (meth) acrylate, polyfunctional urethane (meth) Examples include chlorate, divinylbenzene, triallyl cyanurate, triallyl isocyanate, triallyl trimellitate, diallyl chlorendate, N, N'-phenylene bismaleimide, diallyl phthalate, among others, trimethylolpropane tri (meth) Preference is given to using acrylates.

The isocyanate crosslinking agent and / or polyfunctional monomer (B) described above can be used singly or in combination of two or more.
[Photopolymerizable initiator (C)]
Various things can be used as a photoinitiator (C) without a restriction | limiting. For example, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone [for example, Ciba Geigy, trade name: Darocur 2959], α-hydroxy-α, α'-dimethylacetophenone [for example, Ciba Geigy Acetofenone such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetone [for example, Ciba Geigy, trade name: Irgacure 651], 1-hydroxycyclohexylacetophenone [Ciba Geigy, trade name: Irgacure 184] Photopolymerization initiators; ketal photopolymerization initiators such as benzyldimethyl ketal; other photopolymerization initiators such as halogenated ketones, acyl phosphinoxides, acyl phosphanates, among others, α- Hydroxy-α, α'-dimethylacetophenone Preliminary l-hydroxy acetophenone photopolymerization initiators such as cyclohexyl acetophenone are preferred.

(Photopolymerizable adhesive)
The photopolymerizable pressure-sensitive adhesive of the present invention comprises an isocyanate crosslinking agent and / or a polyfunctional monomer (100) based on 100 parts by weight of the monomer group (A) or a partially polymerized product (A ′) and the monomer group (A). B) is contained in an amount of 0.01 to 2 parts by weight, preferably 0.1 to 1 part by weight, and the photopolymerizable initiator (C) is contained in an amount of 0.1 to 2 parts by weight, preferably 0.2 to 2 parts by weight. Further, it can be obtained by blending other components as required.

  When the isocyanate crosslinking agent and / or the polyfunctional monomer (B) is included in the above range with respect to the monomer group (A), a crosslinked structure is sufficiently and moderately formed, the cohesive force is high, and the photopolymerization has flexibility. Adhesive.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention usually has a dry thickness of 10 to 10% on the surface of a base material (eg, release-treated PET or the like) whose surface has been subjected to a release treatment with a coating solution obtained by arbitrarily adding a solvent to the photopolymerizable pressure-sensitive adhesive. It is obtained by coating with a thickness in the range of 1000 μm, preferably in the range of 25 to 500 μm, and irradiating with active energy rays.

  The monomer group (A) may be preliminarily polymerized and contained in the pressure-sensitive adhesive as a partially polymerized product (A ′). The polymerization rate of the partial polymer (A ′) is preferably 30 to 80%. As a prepolymerization method, a known method can be used, but thermal polymerization using a thermal polymerization initiator is preferable.

  Specifically, as a method of thermal polymerization, a part of the raw material monomer is charged into a reaction vessel, a thermal polymerization initiator is added in an inert gas atmosphere such as nitrogen gas, and the reaction temperature is heated to about 50 to 90 ° C. For 1 to 20 hours. In order to obtain a partially polymerized product, the remaining monomer is then added.

  Examples of the thermal polymerization initiator used for thermal polymerization include azo initiators and peroxide initiators. These initiators are usually used in an amount in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the raw material monomer.

  The weight average molecular weight of the polymer in the partially polymerized product is preferably 200,000 to 700,000. If the weight average molecular weight of the polymer is 700,000 or less, it is not necessary to reduce the proportion of the polymer in the partially polymerized product for coating, and production is possible because the active energy ray irradiation time for polymerization is short. There is no risk of degradation. Moreover, there is no possibility that the softness | flexibility of the adhesive layer obtained may be impaired. The weight average molecular weight of the polymer of the partially polymerized product can be adjusted by adjusting the reaction conditions such as the type and amount of the thermal polymerization initiator, the reaction time, the reaction temperature, or by using a chain transfer agent as appropriate. . Examples of the chain transfer agent include methyl mercaptan, n-dodecyl mercaptan, 2-mercaptoethanol, mercaptoisobutyl alcohol, thioglycerol, methyl thioglycolate, α-methylstyrene dimer, and the like.

Examples of the active energy rays include ultraviolet rays, visible rays, infrared rays, and electron beams. The irradiation conditions of the active energy ray is carried out usually illuminance 1～200MW / active energy rays cm ² integrated light quantity 300～500MJ / cm ² irradiation to. The polymerization rate by irradiation is preferably 90 to 100%. The polymerization rate can be determined by measuring the amount of residual monomer by gas chromatography.

  In the present specification, the pressure-sensitive adhesive sheet includes a double-sided pressure-sensitive adhesive sheet formed only from the pressure-sensitive adhesive layer, a double-sided pressure-sensitive adhesive sheet with a base material on which the pressure-sensitive adhesive layer is formed on both surfaces of the base material, and one surface of the base material. The adhesive sheet with the base material in which the said adhesive layer was formed, and the adhesive sheet by which the cover film by which the peeling process was stuck on the surface which is not in contact with the base material of the adhesive layer of these adhesive sheets are contained.

  The polymer obtained by irradiating the photopolymerizable pressure-sensitive adhesive of the present invention with active energy rays usually has a glass transition temperature (Tg) determined by the Fox equation of −70 ° C. to 0 ° C., preferably −70 ° C. It is in the range of -30 ° C. By having such a glass transition temperature (Tg), a polymer having excellent adhesive strength at room temperature can be obtained.

  The gel fraction of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet thus obtained is usually in the range of 40 to 80%, preferably in the range of 50 to 70%, and has an excellent cohesive force. Effectively suppressed. In the present invention, the gel fraction is determined as follows.

  About 0.1 g of the adhesive layer sample is collected in a sample bottle, 30 cc of ethyl acetate is added and shaken for 4 hours, and then the contents of this sample bottle are filtered through a 200 mesh stainless steel wire mesh to remove the residue on the wire mesh. Dry at 100 ° C. for 2 hours, measure the dry weight, and obtain by the following formula.

［タッチパネル用積層体］
このようにして得られた粘着シートは、各種部材に対して貼着することができるが、特に異種部材を貼り合わせるタッチパネル用部材の貼着に好適である。なお、以下において粘着剤層とは、本願発明の光重合性粘着剤を上記の通り活性エネルギー線照射して得られる、架橋された重合体をいう。

[Laminate for touch panel]
The pressure-sensitive adhesive sheet thus obtained can be attached to various members, and is particularly suitable for attaching a touch panel member to which different types of members are attached. In the following, the pressure-sensitive adhesive layer refers to a crosslinked polymer obtained by irradiating the photopolymerizable pressure-sensitive adhesive of the present invention with active energy rays as described above.

As shown in FIGS. 1 and 2, the touch panel unit includes a resistive touch panel unit (see FIG. 1) and a capacitive touch panel unit (see FIG. 2).
FIG. 1 shows an example of a resistive film type touch panel unit 10-1.

  As shown in FIG. 1, the resistive touch panel unit 10-1 bonds the upper stacked body 11-1 and the lower stacked body 13-1 so that the gap 34 is formed by the bonding agent 30. A spacer 32 is disposed in the gap 34 in order to effectively secure the gap width.

  In the upper laminate 11-1, a transparent conductive film 27-1 made of metal or metal oxide is disposed facing the gap 34. The transparent conductive film 27-1 is made of a conductive material having transparency such as ITO (indium tin oxide), ATO (antimony tin oxide), tin oxide, and is usually made of polyethylene terephthalate (as shown in FIG. It is formed on the surface of the upper electrode support 25-1 made of a transparent member such as PET, polycarbonate (PC), polymethyl methacrylate (PMMA) or glass.

  A surface support 21-1 is disposed on the outermost surface of the upper laminate 11-1, and this surface support 21-1 is usually a transparent member such as highly transparent glass, polycarbonate (PC), polyethylene. It is a transparent film such as terephthalate (PET) or polymethyl methacrylate (PMMA).

In order to adhere the surface support 21-1 and the upper electrode support 25-1, an adhesive layer 23-1 made of the photopolymerizable adhesive of the present invention is formed.
Similarly, the lower laminate 13-1 is formed with a transparent conductive film 27-2 made of metal or metal oxide so as to face the gap 34. The transparent conductive film 27-2 is made of ITO, ATO, It is formed of a conductive material having transparency such as tin oxide. Usually, as shown in FIG. 1, a transparent film such as polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), or transparent such as glass It is formed on the surface of the lower electrode support 25-2 made of a member.

  A deep surface support 21-2 is formed at the deepest portion of the lower laminate 13-1 so as to face the surface of the flat panel display (FPD). The deep surface support 21-2 is made of glass. Such a transparent member or a highly transparent member such as a transparent film such as polycarbonate (PC), polyethylene terephthalate (PET), or polymethyl methacrylate (PMMA).

In the lower laminate 13-1, in order to bond the deep surface support 21-2 and the lower electrode support 25-2, an adhesive layer 23-2 made of the photopolymerizable adhesive of the present invention is formed. ing.
Moreover, the photopolymerizable adhesive of this invention may be used as the bonding agent 30. FIG.

  Note that a circuit is formed in the transparent conductive films 27-1 and 27-2, and by applying pressure with a finger or the like from above the surface support 21-1, a gap 34 in a portion where pressure is applied is formed. The transparent conductive films 27-1 and 27-2 are brought into contact with each other to be energized to detect the pressurized portion.

  In the resistive touch panel unit 10-1, the thickness of the surface support 21-1 is usually 25 to 2000 μm, and the thickness of the upper transparent conductive film 27-1 is usually 10 to 100 nm. The thickness of the body 25-1 is usually 25 to 2000 μm. As described above, the thickness of the pressure-sensitive adhesive layer 23-1 on which these are laminated is usually in the range of 10 to 1000 μm, preferably in the range of 25 to 500 μm.

  Similarly, in the resistive film type touch panel unit, the thickness of the deep surface support 21-2 is usually 25 to 2000 μm, and the thickness of the lower transparent conductive film 27-2 is usually 10 to 100 nm. The thickness of the support 25-2 is usually 25 to 2000 μm. As described above, the thickness of the pressure-sensitive adhesive layer 23-2 on which these layers are laminated is usually in the range of 10 to 1000 μm, preferably in the range of 25 to 500 μm.

Further, in the resistive film type touch panel unit 10-1, the width of the gap 30 formed in the center is usually in the range of 1 to 2000 μm.
On the other hand, the capacitive touch panel unit 10-2 generally includes an upper laminate 15-1 and a lower laminate 15- with a central support 60 made of a highly transparent member such as glass or polycarbonate (PC) interposed therebetween. Often has a structure in which 2 and 2 are arranged.

  In the upper laminate 15-1 of the capacitive touch panel 10-2, a transparent conductive film 57-1 is disposed in contact with the central support 60, and a cover glass or polyethylene terephthalate (PET) is disposed on the outermost surface. ), Polycarbonate (PC), polymethylmethacrylate (PMMA) or the like, a surface support 51-1 made of a light transmissive member is disposed. The transparent conductive film 57-1 is formed of a conductive material having transparency such as ITO, ATO, or tin oxide. An adhesive layer 53-1 made of the photopolymerizable adhesive of the present invention is disposed so as to adhere the transparent conductive film 57-1 and the surface support 51-1. In direct contact with the transparent conductive film 57-1.

  On the other hand, in the lower laminate 15-2 in the capacitive touch panel unit 10-2, a transparent conductive film 57-2 is disposed in contact with the central support 60, and in the deepest part, a cover glass or polyethylene is provided. A surface support 51-2 made of a light transmissive member such as terephthalate (PET), polycarbonate (PC), or polymethyl methacrylate (PMMA) is disposed. The pressure-sensitive adhesive layer 53-2 made of the photopolymerizable pressure-sensitive adhesive of the present invention is disposed so as to bond the transparent conductive film 57-2 and the deepest surface support 51-2. -2 is in direct contact with the transparent conductive film 57-2.

In the capacitive touch panel unit 10-2, the deepest surface support 51-2 is disposed so as to face the flat panel display.
In the capacitive touch panel unit 10-2, the thickness of the upper surface support 51-1 is usually 25 to 2000 μm, and the thickness of the upper transparent conductive film 57-1 is usually 10 to 100 nm. As described above, the thickness of the pressure-sensitive adhesive layer 53-1 for adhering is usually 10 to 1000 μm. In the lower laminate 15-2, the thickness of the lower transparent conductive film 57-2 is usually 10 to 100 nm, and the thickness of the deepest surface support 51-2 is usually 25 to 2000 μm. As described above, the thickness of the pressure-sensitive adhesive layer 53-2 for adhering is usually 10 to 1000 μm. Further, the thickness of the central support 60 between the upper laminate 15-1 and the lower laminate 15-2 is usually in the range of 25 to 1000 μm.

  Note that the transparent conductive films 57-1 and 57-2 form a circuit. Further, in the capacitive touch panel unit 10-2 shown in FIG. 2, the upper laminate 15-1 and the lower laminate 15-2 are provided in two series independently provided in the X-axis direction and the Y-axis direction, respectively. By using this circuit, one of the upper laminate 15-1 or the lower laminate 15-2 can be omitted.

In the capacitive touch panel, the contact position is detected by reading the change in the capacitance of the contact portion caused by the finger touching the surface of the touch panel unit 10-2.
For the touch panel unit as described above, for example, frame printing is performed on the surface of the surface support 51-1 at the edge shown in FIG. This frame printing portion is shown in an enlarged manner in FIG. In FIG. 3, the frame printing portion is indicated by the number 62. The thickness (t ₀ ) of the frame printing portion 62 is normally 10 to 50 μm, and its cross section is formed in a substantially rectangular shape. Since the pressure-sensitive adhesive layer 53-1 is formed by sticking the above-mentioned pressure-sensitive adhesive sheet of the present invention to the surface support 51-1, the pressure-sensitive adhesive layer formed on the pressure-sensitive adhesive sheet is hard and has poor form following ability. As shown in FIG. 4 (a), the adhesive layer 53-1 is located between the surface support 51-1 and the frame printing portion 62 at the end of the frame printing portion 62 and between the surface support 51-1. A gap 64 that is not in contact with any of the edges is formed. Originally, as shown in FIG. 4 (b), the adhesive layer 53-1 must be in close contact with the edge portions of the surface support 51-1 and the frame printing portion 62 without forming the gap 64.

  The pressure-sensitive adhesive layer 53-1 constituting the laminate for a touch panel of the present invention in which a surface support, a pressure-sensitive adhesive layer, and a transparent conductive film (which may have a support) are laminated has a specific composition as described above. It is possible to give excellent cohesiveness by thick film coating and achieve excellent cohesion by being obtained by irradiating active energy rays to the adhesive having, No gap 64 is formed around the periphery.

  Moreover, when the laminated body for touch panels of this invention uses the member which is easy to generate | occur | produce outgas like polycarbonate (PC) as a support body 51-2 as shown in FIG. 5, on the conditions of 80 degreeC of heat test conditions, for example When the test is performed, outgas may be generated from the support, and bubbles 66 may be generated between the support and the adhesive layer. Even if a support that does not generate outgas is used, bubbles 68 may be involved when the support and the pressure-sensitive adhesive layer are bonded to each other, and if this bubble grows due to a temperature change, it will cause foaming.

  The photopolymerizable pressure-sensitive adhesive of the present invention has a specific composition, and the active energy ray irradiated product has a very high cohesive force because it is crosslinked with the component (B). It is possible to suppress foaming due to outgassing and foaming due to entrained bubble growth with high cohesive force. Therefore, in the laminated body for touch panels of this invention, the above foaming can be hardly observed.

  Moreover, in the laminated body for touch panels, when the member is left under durability test conditions (for example, 85 ° C., 85%), moisture may enter from the support side and the end as shown in FIG. Under high temperature conditions, the infiltrated moisture does not precipitate, but when the temperature decreases, the infiltrated moisture precipitates, forming visible droplets, and the touch panel laminate is whitened. , Haze is significantly worsened.

  However, since the pressure-sensitive adhesive layer forming the laminate for a touch panel of the present invention is obtained from a pressure-sensitive adhesive containing a water-soluble N-substituted acrylamide, precipitation of moisture can be suppressed even when water enters from the support layer. In addition, the increase in haze due to the whitening phenomenon is extremely difficult to occur.

  Furthermore, since the photopolymerizable pressure-sensitive adhesive of the present invention does not substantially contain a monomer having an acidic group, even if the photopolymerizable pressure-sensitive adhesive directly contacts a transparent conductive film made of metal or metal oxide. The change of the resistance value of the transparent electrode film is about 10% at the maximum, and this amount of change is an amount that does not cause any problem in driving the touch panel.

  As described above, the laminate for a touch panel of the present invention uses a crosslinked polymer obtained by irradiating a photopolymerizable pressure-sensitive adhesive having a specific composition as an adhesive with an active energy ray, and a surface support and a transparent conductive material. It adheres to the adhesive film, has excellent form following, does not form voids in the frame printed part formed at the edge, and both foam by entrainment and foam by outgas Further, since moisture is not allowed to enter, moisture that has entered the pressure-sensitive adhesive layer is further dispersed, so that the pressure-sensitive adhesive layer is not whitened and the haze value is not increased.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.
Measurement and evaluation were performed by the following methods.

<Weight average molecular weight>
The weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of standard polystyrene were determined using gel permeation chromatography (GPC).
Measuring condition apparatus: HLC-8120 (manufactured by Tosoh Corporation)
Column: G7000HXL (manufactured by Tosoh Corporation)
GMHXL (manufactured by Tosoh Corporation)
G2500HXL (manufactured by Tosoh Corporation)
Sample concentration: 1.5 mg / ml (diluted with tetrahydrofuran)
Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 ml / min
Column temperature: 40 ° C
<Gel fraction>
About 0.1 g of the adhesive layer sample is collected in a sample bottle, 30 cc of ethyl acetate is added and shaken for 4 hours, and then the contents of this sample bottle are filtered through a 200 mesh stainless steel wire mesh to remove the residue on the wire mesh. It dried at 100 degreeC for 2 hours, measured the dry weight, and calculated | required by following Formula.

＜湿熱白化性（ヘイズ）＞
イソプロピルアルコールで拭いたガラス板に、５０mm×６０mmにカットした粘着シートを片側の剥離シートを剥がして貼り付け、５０℃×５atmで２０分間オートクレーブ処理を行った。次いで、１時間室温で静置した後、８５℃、８５％RH環境下に５００時間置き、２３℃、６５％RHで１時間静置下後、ヘイズメーターHM-150（村上色彩研究所(株)製）を用いてJIS K 7361に準拠してヘイズを測定し、粘着剤層の白化を評価した。

<Wet heat whitening (haze)>
A pressure sensitive adhesive sheet cut to 50 mm × 60 mm was attached to a glass plate wiped with isopropyl alcohol by peeling off the release sheet on one side, and autoclaved at 50 ° C. × 5 atm for 20 minutes. Next, after standing at room temperature for 1 hour, placing it in an environment of 85 ° C. and 85% RH for 500 hours, standing at 23 ° C. and 65% RH for 1 hour, and then haze meter HM-150 (Murakami Color Research Laboratory Co., Ltd.) )) And the haze was measured according to JIS K 7361 to evaluate the whitening of the pressure-sensitive adhesive layer.

<Foaming properties>
A pressure-sensitive adhesive sheet cut to 50 mm × 60 mm was attached to a polycarbonate plate wiped with isopropyl alcohol by peeling off the release sheet on one side, and autoclaved at 50 ° C. × 5 atm for 20 minutes. Next, after standing at room temperature for 1 hour, placing it in an environment of 85 ° C. and 85% RH for 500 hours and standing at 23 ° C. and 65% RH for 1 hour, the presence or absence of foaming of the adhesive layer was visually confirmed. . Evaluation criteria are as follows (Evaluation) (Contents)
○: No bubbles can be visually confirmed in the adhesive layer.
Δ: Slight bubbles can be visually confirmed.
X: Large bubbles can be confirmed. Further, the pressure-sensitive adhesive layer floats from the base material or the adherend.

<ITO corrosive>
To the ITO vapor-deposited PET film cut to 10 mm × 100 mm, the pressure-sensitive adhesive sheet was cut to 10 mm × 60 mm, the release sheet on one side was peeled off and attached, and autoclaved at 50 ° C. × 5 atm for 20 minutes. Next, after standing at room temperature for 1 hour, placing it in an environment of 60 ° C. and 90% RH for 500 hours, standing at 23 ° C. and 65% RH for 1 hour, then measuring the resistance value of the ITO deposited film and measuring it in advance The change rate of the resistance value with respect to the resistance value of the pressure-sensitive adhesive sheet that had not been subjected to the above treatment was determined and evaluated according to the following criteria. The resistance value was measured using a tester (manufactured by Sanwa Denki Keiki Co., Ltd .; Digital Multimeter PC510).
(Evaluation) (Content)
○: Change rate of resistance value was less than 10%.
X: Change rate of resistance value was 10% or more.

<Removability and adhesive strength>
The peeled PET film on one side of the pressure-sensitive adhesive sheet was peeled off, a 25 μm thick PET film was bonded to the entire surface, and cut into 25 mm × 150 mm to prepare test pieces. This was laminated to glass and was subjected to 3 reciprocating pressure bonding with a roller having a weight of 2 kg. After the pressure bonding, the sample was allowed to stand in an atmosphere of 23 ° C. × 50% RH for 2 hours, and then the short side of the test piece was peeled off and pulled in the 180 ° direction at a speed of 300 mm / min.

Moreover, the surface state of the glass after peeling a test piece from glass was observed visually by the said adhesive force measurement, and the removability was evaluated according to the following reference | standard.
(Evaluation) (Content)
○: Adhesive adhesion to the glass surface could not be confirmed.
Δ: Slight fogging was confirmed on the glass surface.
X: Adhesive adhesion was clearly confirmed on the glass surface.

<Odor>
The pressure-sensitive adhesive composition was coated on a polyethylene terephthalate (PET) film having a thickness of 38 μm so that the thickness after drying was 50 μm, dried at 80 ° C. for 1 minute, and then the odor of the pressure-sensitive adhesive layer was functionalized in the following five stages. Evaluation was performed. Five persons evaluated each adhesive composition and found the average value.
(Evaluation) (Content)
1: No irritating odor 2: Slight irritating odor 3: Clearly irritating odor 4: Strong irritating odor <Coating property>
The pressure-sensitive adhesive composition was applied to a polyethylene terephthalate (PET) film having a thickness of 38 μm so that the thickness after drying was 200 μm, dried at 80 ° C. for 2 minutes, and then the surface of the coating film was visually confirmed.
○: The coating film surface is smooth and free of bubbles and roughness.
X: Bubbles and roughness are seen on the coating film surface.

<Step following capability>
The peeled PET film on one side of the obtained pressure-sensitive adhesive sheet was peeled off, a 25 μm PET film was bonded, and cut into 50 mm × 50 mm to prepare a test piece.

Next, the PET film cut to 25 mm × 25 mm is placed on the glass plate, the peeled PET film on the other side of the prepared test piece is peeled off, and the PET film on the glass plate is pasted so as to cover the entire surface. The sample was allowed to stand in an 80 ° C. environment for 500 hours and then allowed to stand at room temperature for 1 hour, and the appearance of the step portion was visually observed.
(Evaluation) (Content)
○: Bubbles cannot be visually confirmed in the stepped portion.
Δ: Slight bubbles can be confirmed at the stepped portion by visual attachment.
X: Large bubbles can be confirmed at the stepped portion. Further, the pressure-sensitive adhesive layer floats from the base material or the adherend.

[Production Example 1]
In a reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet pipe, 56 parts by mass of 2-ethylhexyl acrylate (2-EHA), 8 parts by mass of 2-hydroxyethyl acrylate (2-HEA) and acryloylmorpholine ( (ACMO) 16 parts by mass were charged, and the temperature was raised to 50 ° C. while introducing nitrogen gas. Next, 0.1 part by mass of normal dodecyl mercaptan (NDM) as a chain transfer agent and 0.1 part by mass of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were added with stirring. After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C. and then gradually began to decrease. Subsequently, 14 parts by mass of 2-EHA, 2 parts by mass of 2-HEA and 4 parts by mass of ACMO were added. Then, forced cooling with a water bath was performed to obtain an acrylic partial polymer (1). The polymer content in the acrylic partial polymer (1) was 40% by mass, and the weight average molecular weight of the polymer was 600,000.

[Production Example 2]
In a reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet pipe, 56 parts by mass of 2-ethylhexyl acrylate (2-EHA), 8 parts by mass of 2-hydroxyethyl acrylate (2-HEA) and isopropylacrylamide ( NIPAM) was charged at 16 parts by mass, and the temperature was raised to 50 ° C. while introducing nitrogen gas. Next, 0.1 part by mass of normal dodecyl mercaptan (NDM) as a chain transfer agent and 0.1 part by mass of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were added with stirring. After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C. and then gradually began to decrease. Next, 14 parts by mass of 2-EHA, 2 parts by mass of 2-HEA and 4 parts by mass of NIPAM were added to the reaction system. Then, forced cooling with a water bath was performed to obtain an acrylic partial polymer (2). The polymer content in the acrylic partial polymer (2) was 40% by mass, and the weight average molecular weight of the polymer was 600,000.

[Production Example 3]
In a reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet pipe, 56 parts by mass of 2-ethylhexyl acrylate (2-EHA), 8 parts by mass of 2-hydroxyethyl acrylate (2-HEA) and dimethylaminopropyl 16 parts by mass of acrylamide (DMAPAA) was charged, and the temperature was raised to 50 ° C. while introducing nitrogen gas. Next, 0.1 part by mass of normal dodecyl mercaptan (NDM) as a chain transfer agent and 0.1 part by mass of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were added with stirring. After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C. and then gradually began to decrease. Next, 14 parts by mass of 2-EHA, 2 parts by mass of 2-HEA and 4 parts by mass of DMAPAA were added to the reaction system. Then, forced cooling with a water bath was performed to obtain an acrylic partial polymer (3). The polymer content in the acrylic partial polymer (3) was 40% by mass, and the weight average molecular weight of the polymer was 600,000.

[Production Example 4]
In a reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet pipe, 64 parts by mass of butyl acrylate (BA), 8 parts by mass of 2-hydroxyethyl acrylate (2-HEA) and 8 parts by mass of acryloylmorpholine (ACMO) The temperature was raised to 50 ° C. while introducing nitrogen gas. Next, 0.1 part by mass of normal dodecyl mercaptan (NDM) as a chain transfer agent and 0.1 part by mass of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were added with stirring. After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C. and then gradually began to decrease. Next, 16 parts by mass of BA, 2 parts by mass of 2-HEA and 2 parts by mass of ACMO were added to the reaction system. Then, forced cooling with a water bath was performed to obtain an acrylic partial polymer (4). The polymer content in the acrylic partial polymer (4) was 40% by mass, and the weight average molecular weight was 600,000.

[Production Example 5]
In a reaction apparatus equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet pipe, 40 parts by mass of 2-ethylhexyl acrylate (2-EHA), 8 parts by mass of 2-hydroxyethyl acrylate (2-HEA) and acryloylmorpholine ( ACMO) was charged in 32 parts by mass, and the temperature was raised to 50 ° C. while introducing nitrogen gas. Next, 0.1 part by mass of normal dodecyl mercaptan (NDM) as a chain transfer agent and 0.1 part by mass of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were added with stirring. After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C. and then gradually began to decrease. Next, 10 parts by mass of 2-EHA, 2 parts by mass of 2-HEA, and 8 parts by mass of ACMO were added to the reaction system. Then, forced cooling with a water bath was performed to obtain an acrylic partial polymer (5). The polymer content in the acrylic partial polymer (5) was 40% by mass, and the weight average molecular weight of the polymer was 600,000.

[Production Example 6]
A reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet pipe was charged with 56 parts by mass of methoxyethyl acrylate (MEA), 8 parts by mass of 2-hydroxyethyl acrylate (2-HEA) and 16 parts of acryloylmorpholine (ACMO). A mass part was charged, and the temperature was raised to 50 ° C. while introducing nitrogen gas. Next, 0.1 part by mass of normal dodecyl mercaptan (NDM) as a chain transfer agent and 0.1 part by mass of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were added with stirring. After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C. and then gradually began to decrease. Next, 14 parts by mass of MEA, 2 parts by mass of 2-HEA, and 4 parts by mass of ACMO were added to the reaction system. Then, forced cooling with a water bath was performed to obtain an acrylic partial polymer (6). The polymer content in the acrylic partial polymer (6) was 40% by mass, and the weight average molecular weight of the polymer was 600,000.

[Production Example 7]
In a reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet pipe, 40 parts by mass of 2-ethylhexyl acrylate (2-EHA), 24 parts by mass of 2-hydroxyethyl acrylate (2-HEA) and acryloylmorpholine ( (ACMO) 16 parts by mass were charged, and the temperature was raised to 50 ° C. while introducing nitrogen gas. Next, 0.1 part by mass of normal dodecyl mercaptan (NDM) as a chain transfer agent and 0.1 part by mass of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were added with stirring. After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C. and then gradually began to decrease. Next, 10 parts by mass of 2-EHA, 6 parts by mass of 2-HEA and 4 parts by mass of ACMO were added to the reaction system. Then, forced cooling with a water bath was performed to obtain an acrylic partial polymer (7). The polymer content in the acrylic partial polymer (7) was 40% by mass, and the weight average molecular weight of the polymer was 600,000.

[Production Example 8]
In a reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet pipe, 74.4 parts by mass of 2-ethylhexyl acrylate (2-EHA), 4 parts by mass of 2-hydroxyethyl acrylate (2-HEA) and acryloylmorpholine ( ACMO) 1.6 parts by mass was charged, and the temperature was raised to 50 ° C. while introducing nitrogen gas. Next, 0.1 part by mass of normal dodecyl mercaptan (NDM) as a chain transfer agent and 0.1 part by mass of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were added with stirring. After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C. and then gradually began to decrease. Next, 18.6 parts by mass of 2-EHA, 1 part by mass of 2-HEA and 0.4 part by mass of ACMO were added to the reaction system. Then, forced cooling with a water bath was performed to obtain an acrylic partial polymer (8). The polymer content in the acrylic partial polymer (8) was 40% by mass, and the weight average molecular weight of the polymer was 600,000.

[Production Example 9]
In a reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet pipe, 56 parts by mass of 2-ethylhexyl acrylate (2-EHA), 8 parts by mass of 2-hydroxyethyl acrylate (2-HEA) and acrylamide (AM ) 16 parts by mass were charged and heated to 50 ° C. while introducing nitrogen gas. Next, 0.1 part by mass of normal dodecyl mercaptan (NDM) as a chain transfer agent and 0.1 part by mass of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were added with stirring. After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C. and then gradually began to decrease. Next, 14 parts by mass of 2-EHA, 2 parts by mass of 2-HEA, and 4 parts by mass of AM were added to the reaction system. Then, forced cooling with a water bath was performed to obtain an acrylic partial polymer (9). The polymer content in the acrylic partial polymer (9) was 40% by mass, and the weight average molecular weight of the polymer was 600,000.

[Production Example 10]
In a reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet pipe, 55.2 parts by mass of 2-ethylhexyl acrylate (2-EHA), 8 parts by mass of 2-hydroxyethyl acrylate (2-HEA) and acryloylmorpholine ( (ACMO) 16 parts by mass and acrylic acid (AA) 0.8 parts by mass were charged, and the temperature was raised to 50 ° C. while introducing nitrogen gas. Next, 0.1 part by mass of normal dodecyl mercaptan (NDM) as a chain transfer agent and 0.1 part by mass of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were added with stirring. After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C. and then gradually began to decrease. Subsequently, 13.8 parts by mass of 2-EHA, 2 parts by mass of 2-HEA, 4 parts by mass of ACMO and 0.2 part by mass of AA were added to the reaction system. Then, forced cooling with a water bath was performed to obtain an acrylic partial polymer (10). The polymer content in the acrylic partial polymer (10) was 40% by mass, and the weight average molecular weight of the polymer was 600,000.

[Production Example 11]
In a reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet pipe, 56 parts by mass of 2-ethylhexyl acrylate (2-EHA), 8 parts by mass of 2-hydroxyethyl acrylate (2-HEA) and acryloylmorpholine ( (ACMO) 16 parts by mass were charged, and the temperature was raised to 50 ° C. while introducing nitrogen gas. Next, 0.1 part by mass of azobisisobutyronitrile (AIBN), which is a thermal polymerization initiator, was added with stirring. After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C. and then gradually began to decrease. Next, 14 parts by mass of 2-EHA, 2 parts by mass of 2-HEA and 4 parts by mass of ACMO were added to the reaction system, and further forced cooling with a water bath was performed to obtain an acrylic partial polymer (11). The polymer content in the acrylic partial polymer (11) was 15% by mass, and the weight average molecular weight of the polymer was 1 million.

[Example 1]
To 100 parts by mass of the acrylic partial polymer (1), 0.2 parts by mass of trimethylolpropane triacrylate (TMPTA) and 0.2 part by mass of photopolymerization initiator Irgacure 184 (manufactured by Ciba Geigy) were added and deaerated while mixing. A photopolymerizable pressure-sensitive adhesive composition was obtained. This photopolymerizable pressure-sensitive adhesive composition was applied onto a 25 μm-thick polyethylene terephthalate (PET) film that had been peeled off to a coating thickness of 300 μm. The PET film was placed so that the peeled surface was in contact. This was irradiated with light having an irradiation intensity of 5 mW / cm ² for 2 minutes using a high-pressure mercury lamp in a nitrogen gas atmosphere at room temperature to carry out photopolymerization to obtain an adhesive sheet.

[Example 2]
Instead of 0.2 parts by mass of trimethylolpropane triacrylate (TMPTA), 0.2 parts by mass of Takenate D-110N (manufactured by Mitsui Chemicals, trimethylolpropane adduct of xylylene diisocyanate) which is an isocyanate crosslinking agent was used. A pressure-sensitive adhesive sheet was obtained in the same manner as Example 1.

[Example 3]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the acrylic partial polymer (2) was used instead of the acrylic partial polymer (1).

[Example 4]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the acrylic partial polymer (3) was used instead of the acrylic partial polymer (1).

[Example 5]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the acrylic partial polymer (4) was used instead of the acrylic partial polymer (1).

[Example 6]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the acrylic partial polymer (11) was used instead of the acrylic partial polymer (1).

[Reference Example 1]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the acrylic partial polymer (6) was used instead of the acrylic partial polymer (1).

[Reference Example 2]
Instead of 0.2 parts by mass of trimethylolpropane triacrylate (TMPTA), 0.2 parts by mass of Takenate D-110N (manufactured by Mitsui Chemicals, trimethylolpropane adduct of xylylene diisocyanate) which is an isocyanate crosslinking agent was used. A pressure-sensitive adhesive sheet was obtained in the same manner as in Reference Example 1.

[Comparative Example 1]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the acrylic partial polymer (7) was used instead of the acrylic partial polymer (1).

[Comparative Example 2]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the acrylic partial polymer (8) was used instead of the acrylic partial polymer (1).

[Comparative Example 3]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the acrylic partial polymer (5) was used instead of the acrylic partial polymer (1).

[Comparative Example 4]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the acrylic partial polymer (9) was used instead of the acrylic partial polymer (1).

[Comparative Example 5]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the acrylic partial polymer (10) was used instead of the acrylic partial polymer (1).
The unit of the compounding amount in the table is parts by weight. The total monomer is 100 parts by weight.
Abbreviations in Table 1 are as follows.
BA ... butyl acrylate 2-EHA ... 2-ethylhexyl acrylate MEA ... methoxyethyl acrylate 2-HEA ... 2-hydroxyethyl acrylate AA ... acrylic acid ACMO ... acroyl morpholine NIPAM・ Isopropylacrylamide DMAPAA ... dimethylaminopropylacrylamide AM ... acrylamide n-VP ... n-vinylpyrrolidone TMPTA ... trimethylolpropane triacrylate D-110N ... Takenate D-110N (Mitsui Chemicals) Trimethylolpropane adduct of xylylene diisocyanate)
Irgacure 184 ... made by Ciba Geigy

10-1 ... resistive film type touch panel unit 10-2 ... capacitive touch panel unit 11-1 ... upper laminate 13-1 ... lower laminate 15-1 ... upper part Laminate 15-2 ... Lower laminate 21-1 ... Surface support 21-2 ... Deep surface support 23-1 ... Adhesive layer 23-2 ... Adhesive layer 25 -1 ... Upper electrode support 25-2 ... Lower electrode support 27-1 ... Transparent conductive film 27-2 ... Transparent conductive film 30 ... Bonding agent 32 ... Spacer 34 ... Gap 51-1 ... Surface support 51-2 ... Surface support 53-1 ... Adhesive layer 53-2 ... Adhesive layer 57-1 ... Transparent conductive film 57 -2 ... transparent conductive film 60 ... central support 62 ... frame printing part 64 ... gap 66 ... bubble 68 ... bubble

Claims (19)

The following components (a-1) to (a-3)
(a-1) Alkyl (meth) acrylate 40 to 92% by weight
(a-2) Hydroxyl group-containing monomer 5 to 20% by weight
(a-3) Water-soluble N-substituted acrylamide 3 to 25% by weight
And an isocyanate group crosslinking agent with respect to 100 parts by weight of the monomer group (A) (with 100% by weight of all monomers) or a partially polymerized product (A ′) containing substantially no acidic group-containing monomer A photopolymerizable pressure-sensitive adhesive comprising 0.01 to 2 parts by weight of a polyfunctional monomer (B) and 0.1 to 2 parts by weight of a photopolymerization initiator (C).   The weight ratio of (a-2) hydroxyl group-containing monomer to (a-3) water-soluble N-substituted acrylamide is (a-2) :( a-3) = 5: 1 to 1: 7 The photopolymerizable pressure-sensitive adhesive according to claim 1.   The (a-1) alkyl (meth) acrylate is at least one selected from the group consisting of 2-ethylhexyl (meth) acrylate, butyl acrylate, and octyl acrylate, according to claim 1 or 2. Photopolymerizable adhesive.   The photopolymerizable pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the (a-3) water-soluble N-substituted acrylamide has a cyclic structure.   The photopolymerizable pressure-sensitive adhesive according to claim 4, wherein the (a-3) water-soluble N-substituted acrylamide is acryloylmorpholine.   The photopolymerizable pressure-sensitive adhesive according to any one of claims 1 to 5, wherein the monomer group (A) does not contain an alkoxyalkyl (meth) acrylate.   In the said adhesive, the weight average molecular weights of the polymer part in the partial polymer (A ') of the said monomer group (A) are 200,000-700,000, The any one of Claims 1-6 characterized by the above-mentioned. A photopolymerizable pressure-sensitive adhesive as described in 1.   The photopolymerizable pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the pressure-sensitive adhesive is a pressure-sensitive adhesive for a capacitive touch panel in direct contact with a metal or a metal oxide.   The photopolymerizable pressure-sensitive adhesive according to claim 8, wherein the metal oxide is ITO and / or ATO.   The adhesive sheet which has an adhesive layer of thickness 10-1000 micrometers formed by irradiating an active energy ray to the photopolymerizable adhesive described in any one of Claims 1-9.   The pressure-sensitive adhesive sheet according to claim 10, wherein a cover film subjected to a peeling treatment is disposed on at least one surface of the pressure-sensitive adhesive sheet.   A surface support, a pressure-sensitive adhesive layer formed from the photopolymerizable pressure-sensitive adhesive according to any one of claims 1 to 9, and a metal, a metal oxide, a metal with a support, or a metal oxide with a support A laminated body for a touch panel in which a transparent conductive film made of the above is laminated in this order.   The laminate for a touch panel according to claim 12, wherein the laminate for the touch panel is a member forming a capacitive touch panel.   14. The touch panel laminate according to claim 12, wherein frame printing is performed on an edge portion of a surface of the surface support that faces the pressure-sensitive adhesive layer.   The laminate for a touch panel according to claim 14, wherein the frame printing has a thickness in a range of 10 to 50 µm.   16. The metal oxide constituting the transparent conductive film is ITO and / or ATO, and the pressure-sensitive adhesive layer is in direct contact with the transparent conductive film. The laminated body for touchscreens as described in 2.   The thickness of the said surface support body exists in the range of 25-2000 micrometers, The laminated body for touchscreens of any one of Claims 12-16 characterized by the above-mentioned.   The laminate for a touch panel according to any one of claims 12 to 17, wherein the thickness of the transparent conductive film is in the range of 10 to 100 nm.   The laminate for a touch panel according to any one of claims 12 to 18, wherein the pressure-sensitive adhesive layer has a thickness of 10 to 1000 µm.

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