JP5757825B2 - Laminated body and touch panel having the laminated body - Google Patents

Description

  The present invention relates to a laminate for a touch panel forming member having a specific pressure-sensitive adhesive layer, and a touch panel having the laminate.

  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 placed on the outermost surface of the screen, the acrylic adhesive used must have high transparency, and it can be placed in a high-temperature and high-humidity environment in durability tests and accelerated tests. Characteristics such as high heat resistance and moist heat resistance are required.

  Specifically, the touch panel unit, which is a laminate of various materials, is disposed on the outermost surface of the touch panel device, and may cause whitening due to the ingress of moisture from the outside. When sticking together with a pressure-sensitive adhesive, there is a problem that poor appearance is caused by foaming by entraining air and foaming by outgas generated from the material to be laminated.

  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 high temperature conditions, and since PC easily passes moisture, foaming occurs under heat resistant conditions, and the whitening phenomenon of the adhesive layer due to moisture inflow under wet heat conditions is suppressed. There is also the problem that it is difficult. 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 made of a metal or metal oxide, such as indium tin oxide (ITO), which causes corrosion due to contact with acid and increases its resistance value. It is not possible to use means for securing characteristics such as heat resistance and heat-and-moisture resistance using

  Regarding the corrosion of such transparent electrodes made of metals such as ITO or metal oxides, Patent Document 1 (Japanese Patent Laid-Open No. 2010-77287) discloses a polymer mainly composed of alkoxyalkyl acrylate. In this Patent Document 1, it is disclosed to use an alkoxyalkyl acrylate polymer having a weight average molecular weight of 400,000 to 1.6 million and not using a carboxyl group-containing monomer.

  Thus, by using 400,000 to 1.6 million alkoxyalkyl acrylate polymers without using carboxyl group-containing monomers, the corrosion of transparent electrodes made of metals such as ITO or metal oxides is improved to some extent. However, sufficient effects have not been obtained with respect to performance such as heat-and-moisture whitening resistance and heat-resistant foaming resistance. Furthermore, it cannot be said that the workability when the adhesive is applied to a transparent electrode or the like is sufficient.

  Furthermore, since the weight average molecular weight of the polymer disclosed in Patent Document 1 is as large as 400,000 to 1.6 million, the viscosity of the polymer solution increases when the solid content increases when this is dissolved in a solvent to prepare a coating solution. Is too high. In touch panel applications, especially capacitive touch panel applications, a thick adhesive layer is used to bond the surface support to a conductive film such as ITO and to increase the sensitivity to detect changes in capacitance. Need to form. However, since an application liquid having a high solid content cannot be prepared by using an alkoxyalkyl acrylate polymer having a weight average molecular weight of 400,000 to 1.6 million, a preparation liquid having a low solid content is prepared. There is a problem that it is necessary to repeatedly apply, and it is difficult to form a pressure-sensitive adhesive layer having a thickness required for one coating.

  Patent Document 2 (Patent No. 4531099) discloses a weight average molecular weight of 400,000 to 1.6 million obtained by copolymerizing an alkoxyalkyl acrylate and an acrylic monomer having a hydroxyl group as essential monomer components. Disclosed is a pressure-sensitive adhesive composition for transparent plastics, which contains an acrylic polymer and an isocyanate crosslinking agent whose distribution is not 10 to 50, and is substantially free of a carboxyl group-containing monomer in the monomer component constituting the acrylic polymer. . Further, in the examination process of the patent, it is explained by the applicant of the patent that the molecular weight distribution of the acrylic polymer is about 4-9.

JP 2010-77287 A Patent No. 4531099

  The present invention relates to a laminate for a touch panel having a conductive film made of a metal or a metal oxide, excellent in heat-resistant foaming resistance and moist heat resistance (whitening resistance), and having no corrosiveness to a metal or metal oxide, And it aims at providing the touch panel using this.

  In recent years, a display frame has been printed on a surface support constituting the surface of a touch panel. A pressure-sensitive adhesive is also used to bond the surface support on which the frame is printed and a transparent electrode or the like, but the polymers disclosed in Patent Documents 1 and 2 have a large weight average molecular weight, and particularly Since the polymer disclosed in Patent Document 2 has a narrow molecular weight distribution, the pressure-sensitive adhesive does not sufficiently follow the step of the printed portion, and a void is formed, which causes foaming.

  Then, this invention also aims at providing the laminated body for touchscreens using the adhesive which fully follows a printing level | step difference.

The laminate of the present invention is a laminate in which a substrate, an adhesive layer, and a conductive layer are laminated in this order, and the adhesive layer is
(A) a (meth) acrylic polymer having substantially no acidic group, a weight average molecular weight of 50,000 or more and less than 400,000, and a molecular weight distribution of 10 or more and 40 or less;
(B) including an isocyanate-based crosslinking agent,
The (meth) acrylic polymer (A) is at least one selected from the group consisting of alkoxyalkyl (meth) acrylates and alkoxypolyalkylene glycol mono (meth) acrylates (a-1) 20 to 99.5% by weight; A monomer containing 0.5 to 10% by weight of a hydroxyl group-containing monomer (a-2) and a nitrogen-containing monomer (a-3) of 0 to 5% by weight (with all the monomers at 100% by weight). It is characterized by being obtained.

  The (meth) acrylic polymer (A) can be obtained by copolymerizing a monomer containing 0.1 to 4% by weight of the nitrogen-containing monomer (a-3) (with all monomers being 100% by weight). preferable.

  The at least one (a-1) selected from the group consisting of the alkoxyalkyl (meth) acrylate alkoxypolyalkylene glycol mono (meth) acrylate is at least one selected from the group consisting of methoxyethyl acrylate and methoxydiethylene glycol acrylate. It is preferable.

  The pressure-sensitive adhesive layer further has an acidic group substantially obtained by copolymerizing a monomer containing 0.1 to 20% by weight of nitrogen-containing (meth) acrylate (with all the monomers being 100% by weight). In addition, it is preferable that 1 to 10 parts by weight of a (meth) acrylic low molecular weight material having a weight average molecular weight of 5,000 or more and less than 50,000 is included with respect to 100 parts by weight of the (meth) acrylic polymer (A). The gel fraction of the agent layer is preferably 50 to 70%, and the thickness of the pressure-sensitive adhesive layer is usually 10 to 1000 μm.

The conductive layer is preferably a transparent conductive film usually made of metal or metal oxide.
Such a laminate of the present invention is a touch panel comprising a touch panel unit including a laminate in which a surface support, an adhesive layer, and a conductive layer are laminated in this order, and a display laminated on the touch panel unit. Can be suitably used as a laminate in the touch panel unit.

  The touch panel of the present invention is preferably a capacitive touch panel, and in the touch panel, it is preferable that frame printing is performed on the edge of the surface facing the pressure-sensitive adhesive layer of the surface support, The thickness of frame printing is usually in the range of 10-50 μm.

The conductive layer is preferably a circuit pattern using ITO and / or ATO as a metal oxide, and the adhesive layer is in direct contact with the circuit pattern.
The thickness of the surface support is usually in the range of 25 to 2000 μm, and the thickness of the circuit pattern as the conductive layer is preferably in the range of 10 to 100 nm.

  Since the pressure-sensitive adhesive layer in the laminate of the present invention does not substantially contain an acid component, deterioration due to corrosion of a metal or metal oxide such as ITO can be effectively suppressed.

  Further, the pressure-sensitive adhesive composition that forms the pressure-sensitive adhesive layer has a polymer having a weight average molecular weight (Mw) of 50,000 or more and less than 40, so that the solid content in the solvent is high. It can be maintained, can be applied with a sufficient thickness in a single coating process, and has very good step following ability (step following ability).

  Further, since the polymer has a wide molecular weight distribution of 10 to 40, low molecular weight components are appropriately contained in the polymer, and these are excellent in fluidity, so that a good step following property is achieved as the entire pressure-sensitive adhesive layer. The

  Furthermore, since the alkoxyalkyl (meth) acrylate and / or alkoxypolyalkylene glycol mono (meth) acrylate constituting the polymer has a relatively high polarity, the affinity with water is high, and water is present in the pressure-sensitive adhesive layer. Even if it penetrates, it can be uniformly dispersed in the pressure-sensitive adhesive layer, and whitening of the pressure-sensitive adhesive layer is effectively suppressed.

And since a crosslinked structure is formed with an isocyanate type crosslinking agent and cohesion force increases, the adhesive layer in the laminated body of this invention is excellent in heat-resistant foaming resistance and wet heat-resistant stability.
Therefore, in the laminated body of the present invention and the touch panel using the same, the transparent conductive film made of a metal or metal oxide such as ITO is hardly corroded, and the electrical characteristics of the transparent conductive film are hardly changed, and whitening and foaming are performed. Is less likely to occur.

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 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 of the present invention. FIG. 3 is a cross-sectional view schematically showing an example of the configuration of the end portion 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 generated 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 a laminated body for a touch panel. FIG. 7 is a view showing the step following ability of a conventional pressure-sensitive adhesive. FIG. 8 is a view showing the step following ability of the pressure-sensitive adhesive of the present invention.

The present invention is a laminate in which a substrate, a pressure-sensitive adhesive layer, and a conductive layer are laminated in this order,
The pressure-sensitive adhesive layer is
(A) a (meth) acrylic polymer having substantially no acidic group, a weight average molecular weight of 50,000 or more and less than 400,000, and a molecular weight distribution of 10 or more and 40 or less;
(B) including an isocyanate-based crosslinking agent,
The (meth) acrylic polymer (A) is at least one selected from the group consisting of alkoxyalkyl (meth) acrylates and alkoxypolyalkylene glycol mono (meth) acrylates (a-1) 20 to 99.5% by weight; A monomer containing 0.5 to 10% by weight of a hydroxyl group-containing monomer (a-2) and a nitrogen-containing monomer (a-3) of 0 to 5% by weight (with all the monomers at 100% by weight). It is a laminated body characterized by being obtained.
The present invention will be described below.

〔Base material〕
The substrate generally functions as a surface support that constitutes the outermost surface of the touch panel, and is particularly limited as long as it has a function as such a surface support, that is, a certain strength and transparency. Not.

Examples of the material constituting the substrate include polycarbonate, polyethylene terephthalate, polymethyl methacrylate, and glass.
The substrate in the present invention may be a layer having a single layer structure, or may be a layer having a multilayer structure in which a plurality of layers are laminated and the characteristics of each layer are summarized.

(Adhesive layer)
The pressure-sensitive adhesive layer in the laminate of the present invention contains a specific (meth) acrylic polymer (A) and an isocyanate cross-linking agent (B) as described above, and a (meth) acrylic low molecular weight material and others as necessary. May be included. Hereinafter, each component will be described.

<(A) (Meth) acrylic polymer>
((A-1) at least one selected from the group consisting of alkoxyalkyl (meth) acrylates and alkoxypolyalkylene glycol mono (meth) acrylates)
The (meth) acrylic polymer (A) used in the pressure-sensitive adhesive layer constituting the laminate of the present invention is at least selected from the group consisting of alkoxyalkyl (meth) acrylates and alkoxypolyalkylene glycol mono (meth) acrylates. One type (a-1) is copolymerized.

  The (a-1) monomer is not particularly limited as long as it is a (meth) acrylate having an alkoxyalkyl group and / or an alkoxypolyalkylene glycol group as the alcohol-derived portion of the ester structure. Since the alkoxy part of the alkoxyalkyl group, the alkoxy part of the alkoxypolyalkylene glycol group and the alkylene glycol part are excellent in hydrophilicity, in the laminate of the present invention, when water enters the pressure-sensitive adhesive layer, it is dispersed. In addition, water can be retained by the action of hydrophilicity and hydrogen bonding, and water can be effectively suppressed from being precipitated and whitened in the pressure-sensitive adhesive layer.

  As such alkoxyalkyl (meth) acrylate and / or alkoxypolyalkylene glycol mono (meth) acrylate (a-1), from the viewpoint of suppression of whitening, the alkoxy moiety has 1 to 2 carbon atoms. An alkoxyalkyl (meth) acrylate having 1 to 4 carbon atoms in the alkyl portion is preferred, a carbon number in the terminal alkoxy portion is 1 to 2, alkylene glycol is ethylene glycol and / or propylene glycol, and an alkylene glycol unit. Is preferably an alkoxypolyalkylene glycol mono (meth) acrylate having 1 to 3 carbon atoms, more preferably an alkoxyalkyl (meth) acrylate having 1 carbon atom in the alkoxy moiety and 1 to 2 carbon atoms in the alkyl moiety. The carbon number of the terminal alkoxy moiety , And the alkylene glycol is ethylene glycol, alkoxy polyalkylene glycol mono (meth) number of alkylene glycol units is 2 to 3 acrylate are more preferred.

  Examples of such alkoxyalkyl (meth) acrylates include methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3- Examples include ethoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, and 4-ethoxybutyl (meth) acrylate.

  Examples of such alkoxypolyalkylene glycol mono (meth) acrylates include methoxydiethylene glycol mono (meth) acrylate, methoxydipropylene glycol mono (meth) acrylate, ethoxytriethylene glycol mono (meth) acrylate, ethoxydiethylene glycol mono (meta) ) Acrylate and methoxytriethylene glycol mono (meth) acrylate.

Among these, methoxyethyl acrylate and methoxydiethylene glycol monoacrylate are preferable from the viewpoint of suppressing whitening.
In the present invention, at least one (a-1) selected from the group consisting of alkoxyalkyl (meth) acrylates and alkoxypolyalkylene glycol mono (meth) acrylates may be used singly or in combination of two or more.

  Such a monomer (a-1) is 20-99.5 weight% with respect to all the monomers used for superposition | polymerization of the (meth) acrylic-type polymer (A) which forms the adhesive layer in the laminated body of this invention. Is the amount. In the (meth) acrylic polymer (A), the monomer charge ratio is equal to the copolymerization ratio. If the amount of (a-1) is less than 20% by weight, the moisture that has entered the pressure-sensitive adhesive layer cannot be dispersed, and water droplets are formed, so that the pressure-sensitive adhesive layer may be whitened. On the other hand, if the amount of (a-1) exceeds 99.5% by weight, the durability may be impaired.

  Moreover, from the viewpoint of suppression of whitening, the alkoxyalkyl (meth) acrylate (a-1) is 50 to 97.9% by weight with respect to all monomers used for the polymerization of the (meth) acrylic polymer (A). Preferably there is.

((A-2) Monomer having a hydroxyl group)
The (meth) acrylic polymer (A) used in the pressure-sensitive adhesive layer constituting the laminate of the present invention is copolymerized with a hydroxyl group-containing monomer (a-2).

  When at least a part of the monomer (a-2) is crosslinked by the isocyanate-based crosslinking agent (B) described later, high cohesive force is achieved in the pressure-sensitive adhesive layer, and foaming is efficiently suppressed.

  Moreover, as a monomer which has the said hydroxyl group, the (meth) acrylic acid ester which has a hydroxyl group is preferable. Examples of such compounds are 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 8-hydroxyoctyl. Mention may be made of (meth) acrylates.

  Examples of the (meth) acrylic acid ester having a hydroxyl group as described above include 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate from the viewpoint of reactivity with the isocyanate-based crosslinking agent (B). preferable.

The monomer (a-2) having a hydroxyl group described above may be used alone or in combination of two or more.
The monomer (a-2) is in the range of 0.5 to 10% by weight, preferably 2 to 8% by weight, based on the total monomers used for the polymerization of the (meth) acrylic polymer (A) used in the present invention. Is the amount within.

  If the amount of the monomer (a-2) is less than the above range, the amount of copolymerization of other monomers that do not have a hydroxyl group inevitably increases, and the crosslinking structure by the isocyanate-based crosslinking agent (B) described later is sufficient. It may not be formed. On the other hand, when the amount of (a-2) is more than 10% by weight, a crosslinked structure is excessively formed and other characteristics such as step following ability may be insufficient.

((A-3) Nitrogen-containing monomer)
It is preferable that the (meth) acrylic polymer (A) used for the pressure-sensitive adhesive layer constituting the laminate of the present invention is further copolymerized with a nitrogen-containing monomer (a-3).

  As the nitrogen-containing monomer, it is preferable to use at least one selected from the group consisting of an amino group-containing monomer, an amide group-containing monomer, a nitrogen-based heterocyclic ring-containing monomer, and a cyano group-containing monomer.

Examples of amino group-containing monomers include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, etc.
Examples of amide group-containing monomers include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-hexyl (meth) acrylamide and the like. Can
Examples of nitrogen-based heterocyclic ring-containing monomers include vinyl pyrrolidone, acryloyl morpholine, vinyl caprolactam,
Examples of the cyano group-containing monomer include cyano (meth) acrylate.

  Of these, (meth) acrylamide, dimethylaminoethyl (meth) acrylate, and (meth) acryloylmorpholine are preferred from the viewpoint of copolymerization with the monomer (a-1) and the monomer (a-2).

  Such a nitrogen-containing monomer (a-3) is 0 to 5% by weight, preferably 0.1 to 4% by weight, based on all monomers used for the polymerization of the (meth) acrylic polymer (A). By setting it as the amount of a range, the cohesion force of the adhesive layer in the laminated body of this invention can be improved, and also the bridge | crosslinking by an isocyanate type crosslinking agent (B) can be accelerated | stimulated. When the amount of the nitrogen-containing monomer used exceeds 5% by weight, the followability to the step may be lowered.

(Other monomers)
In addition to the monomers (a-1) to (a-3) described above, the (meth) acrylic polymer (A) contains other monomers within a range that does not impair the properties of the polymer (A). It may be polymerized.

  Examples include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, 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 (meth) acrylate, decyl (meth) acrylate , Alkyl (meth) acrylates such as undeca (meth) acrylate, lauryl (meth) acrylate, oleyl (meth) acrylate, n-stearyl (meth) acrylate, iso-stearyl (meth) acrylate and dideca (meth) acrylate (a- 4) is preferably copolymerized, Of these, n-butyl acrylate, 2-ethylhexyl (meth) acrylate, and iso-stearyl acrylate are preferable.

  Such an alkyl (meth) acrylate has good copolymerizability with the monomers (a-1) to (a-3) and can easily adjust the adhesive performance. Therefore, the (meth) acrylic polymer (A ) To 0 to 99.5% by weight, preferably 0 to 47.9% by weight, based on all monomers used for polymerization.

  Further, the (meth) acrylic polymer (A) used in the present invention includes vinyl acetate; (meth) acrylonitrile; cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate; styrene, methylstyrene, Alkyl styrenes such as dimethyl styrene, trimethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene and octyl styrene, fluoro styrene, chloro styrene, bromo styrene, dibromo styrene, iodinated styrene, nitro styrene, acetyl styrene and methoxy styrene Styrenic monomers such as glycidyl (meth) acrylate and the like can be used as long as the effects of the present invention are not impaired.

The other monomers described above can be used singly or in combination of two or more.
((A) (meth) acrylic polymer)
The (meth) acrylic polymer (A) used in the present invention is obtained by copolymerizing the above-described monomers at the above ratio, but has substantially no acidic group. Here, having substantially no acidic group means that a monomer having an acidic group is not added intentionally at the time of copolymerization, and it is usually 0.5 mgKOH / g in terms of the acid value of the resulting polymer. It is as follows.

Examples of the monomer having an acidic group include a monomer having a carboxyl group, a monomer having a phosphoric acid group, and a monomer having a sulfonic acid group.
In the present invention, the (meth) acrylic polymer (A) is not copolymerized with the acidic group-containing monomer as described above. Since the acidic group-containing monomer is not copolymerized in this way, the (meth) acrylic polymer (A) used in the present invention corrodes these even when directly contacted with a metal or metal oxide wiring. In other words, the pressure-sensitive adhesive layer in the laminate of the present invention can be provided with a characteristic that the resistance value of the wiring is not changed over a long period of time.

  Furthermore, the (meth) acrylic polymer (A) used in the present invention has a weight average molecular weight of 50,000 or more and less than 400,000, preferably 200,000 to 380,000. In addition, in this specification, a weight average molecular weight is a weight average molecular weight of standard polystyrene conversion measured by GPC (gel permeation chromatography). Moreover, molecular weight distribution (Mw / Mn) is 10-40, Preferably it is 12-30.

  Conventionally used pressure-sensitive adhesives have high molecular weight acrylic polymers having a weight average molecular weight of about 400,000 to 1.6 million, but in the present invention, as described above, (meth) acrylic polymers are used in comparison with conventional ones. By using the (meth) acrylic polymer (A) having a low weight average molecular weight, the pressure-sensitive adhesive layer becomes soft and the shape following property is improved. Further, when the pressure-sensitive adhesive layer is adhered to the adherend, It becomes difficult to entrain. Even when a (meth) acrylic polymer (A) having a weight average molecular weight of less than 50,000 is used, sufficient cohesive force cannot be obtained. When the weight average molecular weight is 400,000 or more, the step following ability and the thick film coatability of the pressure-sensitive adhesive layer are insufficient.

  Furthermore, the molecular weight distribution of the (meth) acrylic polymer (A) is wide, and the polymer contains moderately relatively low molecular weight components to relatively high molecular weight components. By having such a wide molecular weight distribution, it is considered that a relatively low molecular weight polymer fills a gap between relatively high molecular weight polymers in the adhesive as shown in FIG. The fluidity | liquidity which was excellent in the said adhesive layer was provided, and the level | step difference followability excellent in the said adhesive layer was provided rather than the example using the conventional adhesive shown in FIG. In order to make the molecular weight distribution of the (meth) acrylic polymer (A) within the above range, adjusting the reaction temperature, adding an initiator or a monomer during the polymerization, and the like can be mentioned.

  In general, the molecular weight distribution of the polymer constituting the pressure-sensitive adhesive varies depending on the application of the pressure-sensitive adhesive. For example, a general-purpose pressure-sensitive adhesive has a wide molecular weight distribution. On the other hand, in applications where a small amount of low molecular weight component bleed-out and foaming due to outgassing from the adherend caused by insufficient cohesive force due to the large amount of low molecular weight components are problems, such as those used for touch panels Usually, the molecular weight distribution is set narrow. Actually, the molecular weight distribution of the acrylic polymer constituting the pressure-sensitive adhesive composition disclosed in Patent Document 2 is about 4 to 9.

  On the other hand, in the present invention, by using the (meth) acrylic polymer (A) having a specific composition, even when the molecular weight distribution is set within the above range, the low molecular weight component bleeds out and adheres under high temperature and high humidity. Foaming of the agent is prevented to such an extent that it does not become a problem even in applications such as a touch panel, and since the molecular weight distribution is wide, a step following property based on excellent fluidity is imparted to the adhesive layer.

  In the present invention, the (meth) acrylic polymer (A) has a glass transition temperature (Tg) determined by the Fox equation of usually -70 ° C to 0 ° C, preferably -70 ° C to -30 ° C. It is in. By using the (meth) acrylic polymer (A) having such a glass transition temperature (Tg), a pressure-sensitive adhesive layer having excellent adhesive strength at room temperature can be obtained.

(Method for producing (meth) acrylic polymer (A))
The (meth) acrylic polymer (A) can be produced by a known method, but is preferably produced by solution polymerization. In the solution polymerization, for example, ethyl acetate, methyl ethyl ketone, toluene, acetone or the like can be used as a polymerization solvent.

  Specifically, the polymerization solvent and raw material monomer are charged into the reaction vessel in the proportions described above, a polymerization initiator is added under an inert gas atmosphere such as nitrogen gas, and the reaction temperature is heated to about 50 to 90 ° C., React for 4-20 hours.

  Examples of the reaction initiator used for solution 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. Moreover, you may add suitably a polymerization initiator, a chain transfer agent, a raw material monomer, and a solvent suitably during the said polymerization reaction.

  Under the above conditions, the weight average molecular weight of the (meth) acrylic polymer (A) to be obtained is determined according to known techniques, such as the type and amount of the solvent used, the type and amount of the polymerization initiator, the reaction time, the reaction temperature, etc. It can be adjusted by adjusting the reaction conditions.

<(B) Isocyanate-based crosslinking agent>
The pressure-sensitive adhesive layer in the laminate of the present invention further contains an isocyanate-based crosslinking agent (B). The cross-linking agent (B) causes a cross-linking reaction with the hydroxyl group derived from the monomer (a-2) in the (meth) acrylic polymer (A) to form a three-dimensional cross-linking structure, resulting in high aggregation in the pressure-sensitive adhesive layer. Power is granted. For example, a metal chelate-based crosslinking agent other than an isocyanate-based crosslinking agent may have insufficient durability because the crosslinked structure becomes weak under high temperature conditions.

  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. A compound having: a compound obtained by addition reaction with a polyhydric alcohol such as trimethylolpropane or pentaerythritol, an isocyanurate compound, a burette type compound, and a known polyether polyol, polyester polyol, acrylic polyol, polybutadiene polyol, poly Has two or more isocyanate groups in the urethane prepolymer type molecule that has undergone addition reaction with isoprene Mention may be made of the compound.

  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 preferred, and hexamethylene diisocyanate and its trimethylolpropane adduct are preferred from the viewpoint of improving the step following property of the affixed surface and improving the heat resistant foaming property.

The isocyanate-based crosslinking agent (B) described above can be used alone or in combination of two or more.
By blending the isocyanate-based cross-linking agent (B), the cohesive force of the pressure-sensitive adhesive layer in the laminate of the present invention is improved, and even when air bubbles are slightly involved at the time of pasting, the expansion of the air bubbles can be suppressed, Excellent heat-resistant foaming properties are exhibited.

<(Meth) acrylic low molecular weight product>
The pressure-sensitive adhesive layer in the laminate of the present invention has a nitrogen-containing (meta) from the viewpoint of improving the conformability to the base material and the adherend and improving the cohesive force due to the interaction with the (meth) acrylic polymer (A). ) It is preferable to contain a (meth) acrylic low molecular weight substance substantially free from an acidic group, which is obtained by polymerizing a monomer containing an acrylic monomer. The meaning of “substantially no acidic group” is the same as in the (meth) acrylic polymer (A).

  Examples of the nitrogen-containing (meth) acrylic monomer include the nitrogen-containing monomers described above. Among these, the cohesive force of the pressure-sensitive adhesive is improved, and further, crosslinking with the isocyanate-based crosslinking agent (B) is promoted. From the viewpoint that it can be used, dimethylaminoethyl (meth) acrylate and acrylamide are preferable. The nitrogen-containing (meth) acrylic monomer is based on the total monomers used for the polymerization of (meth) acrylic low molecular weight substances from the viewpoint of improving cohesion by interaction with the hydroxyl group of the (meth) acrylic polymer. , Preferably in an amount of 0.1 to 20% by weight.

Of course, the (meth) acrylic low molecular weight substance may have a nitrogen-free (meth) acrylic monomer as a constituent monomer, and examples of such a monomer include methyl (meth) acrylate. , Ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meta ) Acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undeca (meth) acrylate and dideca (meth) ) Alkyl (meth) acrylates such as acrylate,
2-hydroxyethyl (meth) acrylate, 2-hydroxyethylpropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate And hydroxyalkyl (meth) acrylates such as 8-hydroxyoctyl (meth) acrylate.

Furthermore, a styrene monomer such as α-methylstyrene may be copolymerized.
Among these, from the viewpoint of polymerizability and compatibility with the (meth) acrylic polymer (A), the alkyl (meth) acrylate is 80% of all monomers used for the polymerization of the (meth) acrylic low molecular weight polymer. It is preferably used at a ratio of ˜99% by weight.

  The weight average molecular weight of the (meth) acrylic low molecular weight substance described above is 5,000 or more and less than 50,000. Such a (meth) acrylic low molecular weight product can be produced by various known methods.

  Such (meth) acrylic low molecular weight substances may be used alone or in combination of two or more. In the pressure-sensitive adhesive, usually 0 to 20 parts per 100 parts by weight of the (meth) acrylic polymer (A). Part by weight, preferably 1 to 10 parts by weight is included.

<Other ingredients>
In the pressure-sensitive adhesive layer in the laminate of the present invention, an antioxidant, a metal corrosion inhibitor, a light stabilizer, a tackifier, a plasticizer, as long as the effect of the pressure-sensitive adhesive layer in the laminate of the present invention is not impaired. An antistatic agent, a crosslinking accelerator, a reworking agent, and the like can also be blended.

Examples of the metal corrosion inhibitor include benzotriazole compounds, phenol compounds, and aromatic amine compounds.
The blending amount of these other components is appropriately adjusted within a range not impairing the effects of the present invention.

[Conductive layer]
The conductive layer in the laminate of the present invention may have a single layer structure made of metal or metal oxide, or may have a multilayer structure in which an electrode support or the like is further laminated on the layer. In the case of a multilayer structure, the pressure-sensitive adhesive layer in the laminate of the present invention is in contact with the electrode support.

  Examples of the metal or metal oxide include ITO (indium tin oxide), ATO (antimony tin oxide), and tin oxide. Since these are excellent in transparency, they are suitable as a transparent conductive film in a touch panel.

Furthermore, examples of the constituent material of the electrode support include highly transparent glass, polycarbonate, polymethyl methacrylate, and polyethylene terephthalate.
The conductive layer preferably has a single-layer structure made of metal or metal oxide, which is mainstream in capacitive touch panels.

[Method for producing laminate]
The laminate of the present invention is formed by laminating the base material, the pressure-sensitive adhesive layer, and the conductive layer described above in this order.

Although the manufacturing method of the said laminated body is not specifically limited, For example, (1) The adhesive composition which forms an adhesive layer is apply | coated on a base material, an adhesive layer is formed, and also a conductive layer on the adhesive layer. (2) Method of forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive composition to form a pressure-sensitive adhesive layer on the conductive layer, and further laminating a substrate on the pressure-sensitive adhesive layer (3) Peeling in advance A pressure-sensitive adhesive layer is formed on the liner, this (pressure-sensitive adhesive layer) is transferred onto the substrate, the release liner is peeled off, and the transferred pressure-sensitive adhesive layer is contacted with the conductive layer. (4) A pressure-sensitive adhesive layer is previously formed on a release liner, this (pressure-sensitive adhesive layer) is transferred onto the conductive layer, and the release liner is peeled off. Furthermore, the transferred adhesive layer is placed together with the conductive layer so that the adhesive layer is in contact with the substrate. How to sticking, and the like.

  The pressure-sensitive adhesive composition usually contains an isocyanate-based crosslinking agent (B) in an amount of 0.1 to 2 with respect to 100 parts by weight of the (meth) acrylic polymer (A) and the (meth) acrylic polymer (A). Part by weight, preferably 0.1 to 1 part by weight, and can be obtained by blending other components as required.

  Further, when the pressure-sensitive adhesive composition is applied on a substrate or a conductive layer, or when a pressure-sensitive adhesive layer is formed on a release liner (eg, release-treated PET), a pressure-sensitive adhesive layer forming component is As with known pressure-sensitive adhesives, they are diluted to an appropriate concentration with a solvent, coated on a substrate or a release liner, and dried. Thereby, an adhesive layer is formed.

  In addition, although there is no restriction | limiting in particular in the said coating method, For example, it can apply | coat using a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater.

  The coating solution containing the (meth) acrylic polymer (A), the crosslinking agent (B), and other components used as needed in the present invention is a (meth) acrylic polymer (A). Since the weight average molecular weight (Mw) is low, the concentration of non-volatile components can be easily adjusted in a solvent such as ethyl acetate, methyl ethyl ketone, acetone, and toluene. Therefore, by using such a coating solution, the thickness of the pressure-sensitive adhesive layer after coating can be easily set to a desired thickness. In particular, the coating solution can easily increase the non-volatile content, for example, the non-volatile content can be adjusted within a range of 10 to 70%, preferably 30 to 60%. The pressure-sensitive adhesive layer can be formed with a small number of coatings.

  Further, by using a solution having a high nonvolatile content as described above, the leveling property of the coating film after coating and drying is improved, and the drying time is shortened and the workability is improved. Furthermore, since the amount of volatile solvent is small, the burden on the environment is also reduced.

  Utilizing such characteristics, the pressure-sensitive adhesive layer in the laminate of the present invention has a thickness within the range of 10 to 1000 μm, preferably within the range of 25 to 500 μm after drying the coating solution. It is obtained by coating so as to have a thickness.

  When this adhesive application solution is applied onto a release liner, it is applied onto the liner, and after removing the solvent, the surface of the formed adhesive layer (the surface not in contact with the release liner) Another release liner is stuck, and it is usually cured at a temperature of 0 to 50 ° C. for 1 to 10 days, and crosslinked with an isocyanate-based crosslinking agent (B).

Thereby, the gel fraction of the formed pressure-sensitive adhesive layer is usually in the range of 50 to 80%, preferably 50 to 70%. In the present invention, the gel fraction is determined as follows.
About 0.1 g of the adhesive layer sample after aging at 23 ° C for 7 days was collected in a sample bottle, added with 30 cc of ethyl acetate, shaken for 4 hours, and then filtered the contents of this sample bottle through a 200 mesh stainless steel wire mesh. Then, the residue on the wire mesh is dried at 100 ° C. for 2 hours, the dry weight is measured, and the following formula is obtained.

［タッチパネル］
本発明のタッチパネルは、表面支持体と、粘着剤層と、導電層とがこの順に積層された積層体を含むタッチパネルユニットと、該タッチパネルユニット上に積層されたディスプレイとからなるタッチパネルであって、前記積層体が、本発明の積層体であることを特徴としている。すなわち、本発明の積層体における基材は、本発明のタッチパネルにおける表面支持体として機能する。

[Touch panel]
The touch panel of the present invention is a touch panel comprising a touch panel unit including a laminate in which a surface support, an adhesive layer, and a conductive layer are laminated in this order, and a display laminated on the touch panel unit, The laminate is the laminate of the present invention. That is, the base material in the laminated body of the present invention functions as a surface support in the touch panel of the present invention.

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, in the resistive touch panel unit 10-1, the upper laminate 11-1 and the lower laminate 13-1 are separated so that the gap 34 is formed by the bonding agent 30. A spacer 32 is arranged in the gap 34 in order to secure an effective space.

  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 formed of a conductive material having transparency such as ITO (indium tin oxide), ATO (antimony tin oxide), tin oxide, and usually, as shown in FIG. 1, polyethylene terephthalate ( PET) or an upper electrode support 25-1 made of 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 film such as highly transparent glass or polycarbonate, polyethylene terephthalate (PET). It is.

In order to bond the surface support 21-1 and the upper electrode support 25-1, an adhesive layer 23-1 is formed. The upper laminated body 11-1 described above corresponds to the laminated body of the present invention.
Similarly, a transparent conductive film 27-2 made of metal or metal oxide is formed on the lower laminate 13-1 so as to face the gap 34. This transparent conductive film 27-2 is made of ITO (indium). Tin oxide), ATO (antimony tin oxide), tin oxide and other conductive materials having transparency, and usually a lower electrode support 25- made of polyethylene terephthalate (PET) or glass as shown in FIG. 2 is formed on the surface.

  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 display. The deep surface support 21-2 is made of a transparent material such as glass or polycarbonate. It is formed from a high member.

  In the lower laminate 13-1, an adhesive layer 23-2 is formed in order to bond the deep surface support 21-2 and the lower electrode support 25-2. The lower laminated body 13-1 described above also corresponds to the laminated body of the present invention.

Moreover, the adhesive which comprises the adhesive layer in the laminated body of this invention as the said bonding agent 30 may be used.
The transparent conductive films 27-1 and 27-2 are formed as a circuit pattern, and the pressure 34 is applied to the gap 34 by applying pressure from above the surface support 21-1. 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 for laminating them is in the range of 10 to 1000 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 electrode 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 are laminated is in the range of 10 to 1000 μm.

Further, in the resistive film type touch panel unit 10-1, the width of the gap 34 formed at the center is usually in the range of 100 to 300 μm.
On the other hand, as shown in FIG. 2, the capacitive touch panel unit 10-2 generally includes an upper laminated body 15-1 and a lower part sandwiching a central support 60 made of a highly transparent member such as glass or polycarbonate. In many cases, the laminated body 15-2 has a structure in which the laminated body 15-2 is disposed to face the laminated body 15-2.

  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. A surface support 51-1 made of a light transmissive member such as) is disposed. An adhesive layer 53-1 is disposed so as to adhere the transparent conductive film 57-1 and the surface support 51-1, and the adhesive layer 53-1 is in direct contact with the transparent conductive film 57-1. doing. The upper laminate 15-1 described above corresponds to the laminate of the present invention.

  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) is disposed. An adhesive layer 53-2 is disposed so as to bond the transparent conductive film 57-2 and the deepest surface support 51-2, and the adhesive layer 53-2 is formed of the transparent conductive film 57-2. In direct contact. The lower laminated body 15-2 described above also corresponds to the laminated body of the present invention.

In the capacitive touch panel unit 10-2, the deepest surface support 51-2 is arranged to face the 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. The thickness of the pressure-sensitive adhesive layer 53-1 for adhering is 10 to 1000 μm as described above. 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 10 to 1000 μm. In addition, 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 2000 μm.

  The upper transparent conductive film 57-1 and the lower transparent conductive film 57-2 form a circuit pattern. 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 touch panel is driven 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 edge of the upper surface support 51-1 shown by A in FIG. 2 that contacts the adhesive layer 53-1 of the surface support 51-1. Is done. 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. As described above, the pressure-sensitive adhesive layer 53-1 is formed by transferring the pressure-sensitive adhesive layer previously formed on the release liner onto the conductive layer, peeling the release liner, and exposing the substrate (surface support) to the surface of the pressure-sensitive adhesive layer. Since the adhesive layer is hard and lacks shape followability, it is the end of the frame printing portion 62 and the surface as shown in FIG. A gap 64 is formed between the support 51-1 and the pressure-sensitive adhesive layer 53-1 that is not in contact with either the surface support 51-1 or the edge of the frame printing portion 62. 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.

  However, in the case of a pressure-sensitive adhesive based on a pressure-sensitive adhesive component having a weight average molecular weight of 400,000 to 1.6 million and having a narrow molecular weight distribution as in the past, the shape of the pressure-sensitive adhesive layer is affected by such a very fine change in shape. Therefore, the gap 64 is formed without being completely changed.

  As described above, the pressure-sensitive adhesive layer 53-1 constituting the laminate of the present invention in which the surface support, the pressure-sensitive adhesive layer, and the conductive film (which may have a support) are laminated includes a specific monomer (a-1 ), A (meth) acrylic polymer (A) having a weight average molecular weight (Mw) of 50,000 to less than 400,000 and a molecular weight distribution of 10 to 40 is used. Even in a state of being cross-linked with a high cohesive force, it has a very excellent form following ability, and no voids 64 are formed around the frame printing portion 62, and foaming is suppressed. The

  When the touch panel of the present invention uses a member that easily generates outgas such as polycarbonate (PC) as the support 51-2 as shown in FIG. Outgassing from the body may occur, generating air bubbles 66 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 pressure-sensitive adhesive layer in the touch panel of the present invention has a specific composition, a weight average molecular weight (Mw) of 50,000 or more and less than 400,000, a molecular weight distribution as wide as 10 to 40, and a (meth) acrylic type excellent in fluidity. Since the polymer (A) is used, the pressure-sensitive adhesive layer can sufficiently follow the support (which has irregularities when viewed from a microscopic viewpoint) and printing steps of frame printing, and almost no bubbles are involved. Moreover, since the polymer (A) is cross-linked with the isocyanate-based cross-linking agent (B), the pressure-sensitive adhesive layer has a very high cohesive force. Foaming due to high cohesion can be suppressed. Therefore, the foaming as described above can be hardly observed in the touch panel of the present invention.

  In the touch panel, when the touch panel is left under the durability test conditions (60 ° C., 90%), moisture may enter from the support and the end as shown in FIG. Under the condition where the temperature is high, the infiltrated moisture does not precipitate, but when the temperature is lowered, the infiltrated moisture is precipitated, the touch panel is whitened, and the haze is remarkably deteriorated (FIG. 6). The pressure-sensitive adhesive layer forming the touch panel of the present invention has not only high cohesion as described above, but also an alkoxyalkyl (meth) acrylate (a-1) that is a constituent monomer of the (meth) acrylic polymer (A). Since the alkoxy moiety has hydrophilicity and can also participate in hydrogen bonding, it can be uniformly dispersed and retained in the pressure-sensitive adhesive layer when moisture enters, so that the whitening phenomenon Deterioration of haze due to is hardly caused.

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

  As described above, the touch panel of the present invention includes a (meth) acrylic polymer (A) having a specific composition as an adhesive layer and having a weight average molecular weight of 50,000 or more and less than 400,000 and a molecular weight distribution of 10 to 40, and an isocyanate-based cross-linking. A surface support (base material) and a conductive layer (eg, transparent conductive film) are adhered using a pressure-sensitive adhesive layer having an adhesive (B), and the pressure-sensitive adhesive layer has excellent form following properties. In addition, no voids are formed in the frame printing portion formed at the edge, and both foaming due to entrainment and foaming due to outgassing can be suppressed. Furthermore, alkoxyalkyl (meth) acrylate and alkoxypolyalkylene can be suppressed. Under the influence of the hydrophilic portion of glycol mono (meth) acrylate, the pressure-sensitive adhesive layer is hardly whitened and the haze is hardly deteriorated.

EXAMPLES Next, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited thereto.
The physical properties of the pressure-sensitive adhesive were measured and evaluated by the methods shown below.

〔Measuring method〕
<Molecular weight and molecular weight distribution>
The weight average molecular weight (Mw) and the number average molecular weight (Mn) in terms of standard polystyrene were determined by gel permeation chromatography (GPC) under the following conditions.

(GPC measurement conditions)
Measuring device: HLC-8120GPC (manufactured by Tosoh Corporation)
GPC column configuration: The following five columns (all manufactured by Tosoh Corporation)
(1) TSK-GEL HXL-H (guard column)
(2) TSK-GEL G7000HXL
(3) TSK-GEL GMHXL
(4) TSK-GEL GMHXL
(5) TSK-GEL G2500HXL
Diluted with tetrahydrofuran so that the sample concentration is 1.0 mg / cm ³ Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 cm ³ / min
Column temperature: 40 ° C.

<Gel fraction>
About 0.1 g of the pressure-sensitive adhesive composition obtained in Examples and Comparative Examples after aging at 23 ° C. for 7 days was collected in a sample bottle, added with 30 cc of ethyl acetate, shaken for 4 hours, and then the contents of this sample bottle. Was filtered through a 200 mesh stainless steel wire mesh, the residue on the wire mesh was dried at 100 ° C. for 2 hours, and the dry weight was measured.

＜ヘイズ（耐白化性）＞
イソプロピルアルコールで拭いたポリカーボネート板に５０mm×６０mmにカットした粘着シートを貼り付け、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。

<Haze (whitening resistance)>
An adhesive sheet cut to 50 mm × 60 mm was attached to a polycarbonate plate wiped with isopropyl alcohol, 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 resistance>
An adhesive sheet cut to 50 mm × 60 mm was attached to a polycarbonate plate wiped with isopropyl alcohol, and autoclaved at 50 ° C. × 5 atm for 20 minutes. Subsequently, after leaving still at room temperature for 1 hour, it was left to stand in 80 degreeC and dry environment for 500 hours, and left still at 23 degreeC and 65% RH for 1 hour, Then, the presence or absence of foaming of an adhesive layer was confirmed visually. The evaluation criteria are as follows. (Evaluation) (Contents)
A: No bubbles can be visually confirmed in the pressure-sensitive adhesive layer. B: A few bubbles can be visually confirmed. Δ: Although it is practically usable, bubbles can be clearly confirmed visually. X: Large bubbles can be confirmed. Further, the pressure-sensitive adhesive layer floats from the base material or the adherend.

<ITO corrosiveness>
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut to 10 mm × 60 mm and pasted on an ITO-deposited PET film cut to 10 mm × 100 mm, 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 before the test was obtained by comparison with the resistance value before the test. The resistance value was measured using a tester (manufactured by Sanwa Denki Keiki Co., Ltd .; Digital Multimeter PC510).

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

Next, a 25 μm thick PET film cut to 25 mm × 25 mm is placed on a 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 covered to cover the entire surface. After standing at 80 ° C. for 500 hours, let it stand at room temperature for 1 hour, the appearance of the step between the glass plate and the PET film placed on the glass and covered with the test piece It was observed visually.
(Evaluation) (Content)
A: Bubbles cannot be visually confirmed at the stepped portion.
○: A slight amount of air bubbles can be confirmed at the stepped portion by visual attachment.
Δ: Bubbles can be visually confirmed at the stepped portion. Furthermore, after 24 hours of standing, bubbles can be clearly confirmed.

X: Large bubbles can be confirmed at the stepped portion. Further, the pressure-sensitive adhesive layer floats from the base material or the adherend.

<Step adhesive strength>
Remove the release sheet on one side of the adhesive sheet (adhesive layer thickness is 50 μm) obtained in the examples and comparative examples, paste a 25 μm PET film on the exposed adhesive layer surface, and cut it to a width of 10 mm to create a test piece did.

  Next, the other release sheet of the test piece is peeled off, and the adhesive layer exposed at the step portion (step height 30 μm) of the two 25 μm-thick PET films that are adhered to each other with a gap is placed with a width of 25 mm. The test piece was bonded together.

The test piece was peeled off in the 180 ° direction at 300 mm / min from the PET film that had been stuck together, and the adhesive strength (force required for peeling) of the pressure-sensitive adhesive layer was measured.
[Production Example 1]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 23 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Part, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

  Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 2 hours in a nitrogen atmosphere. Further, 0.2 part by weight of azobisisobutyronitrile was further added to add 70 parts by weight. The polymerization reaction was carried out at 3 ° C. for 3 hours.

After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 1 having a weight average molecular weight of 300,000 and a weight average molecular weight / number average molecular weight of 20.
[Production Example 2]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 23 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Part, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 2 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc), adjusted to a solid content concentration of 30%, and an acrylic polymer 2 having a weight average molecular weight of 300,000 and a weight average molecular weight / number average molecular weight of 11 was obtained.
[Production Example 3]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 23 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Part, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

  Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 2 hours in a nitrogen atmosphere. Further, 0.3 part by weight of azobisisobutyronitrile was added to add 70 parts by weight. The polymerization reaction was carried out at 3 ° C. for 3 hours.

After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 3 having a weight average molecular weight of 300,000 and a weight average molecular weight / number average molecular weight of 30.
[Production Example 4]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 23 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) And 150 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

  Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 2 hours in a nitrogen atmosphere. Further, 0.3 part by weight of azobisisobutyronitrile was added to add 70 parts by weight. The polymerization reaction was carried out at 3 ° C. for 3 hours.

After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 4 having a weight average molecular weight of 70,000 and a weight average molecular weight / number average molecular weight of 20.
[Production Example 5]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 23 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 110 parts by weight of ethyl acetate (EtAc) and 10 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 2 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 5 having a weight average molecular weight of 380,000 and a weight average molecular weight / number average molecular weight of 20.
[Production Example 6]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 22 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 1 part by weight of acrylamide (AM), 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were heated to 70 ° C. while introducing nitrogen gas.

  Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 2 hours in a nitrogen atmosphere. Further, 0.2 part by weight of azobisisobutyronitrile was further added to add 70 parts by weight. The polymerization reaction was carried out at 3 ° C. for 3 hours.

After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 6 having a weight average molecular weight of 300,000 and a weight average molecular weight / number average molecular weight of 20.
[Production Example 7]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 18 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 5 parts by mass of acrylamide (AM), 110 parts by weight of ethyl acetate (EtAc) and 10 parts by weight of methyl ethyl ketone (MEK) were heated to 70 ° C. while introducing nitrogen gas.

Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 2 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 7 having a weight average molecular weight of 300,000 and a weight average molecular weight / number average molecular weight of 20.
[Production Example 8]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 22 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 1 part by weight of dimethylaminomethyl methacrylate (DM), 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

  Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 2 hours in a nitrogen atmosphere. Further, 0.2 part by weight of azobisisobutyronitrile was further added to add 70 parts by weight. The polymerization reaction was carried out at 3 ° C. for 3 hours.

After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 8 having a weight average molecular weight of 300,000 and a weight average molecular weight / number average molecular weight of 20.
[Production Example 9]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 23 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Part, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

Next, 0.15 parts by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 9 having a weight average molecular weight of 300,000 and a weight average molecular weight / number average molecular weight of 9.
[Production Example 10]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 23 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Part, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 10 having a weight average molecular weight of 300,000 and a weight average molecular weight / number average molecular weight of 3.
[Production Example 11]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 23 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) And 100 parts by weight of ethyl acetate (EtAc) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

  Next, 0.05 parts by weight of azobisisobutyronitrile (AIBN) was added, the polymerization reaction was carried out at 70 ° C. for 2 hours in a nitrogen atmosphere, and 1 part by weight of azobisisobutyronitrile was added to 30 parts by weight of ethyl acetate. The solution in which the part was dissolved was dropped over 2 hours. Thereafter, a polymerization reaction was performed at 70 ° C. for 2 hours.

After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 11 having a weight average molecular weight of 300,000 and a weight average molecular weight / number average molecular weight of 45.
[Production Example 12]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 22 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 1 part by weight of acrylic acid (AA), 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were heated to 70 ° C. while introducing nitrogen gas.

  Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 2 hours in a nitrogen atmosphere. Further, 0.2 part by weight of azobisisobutyronitrile was further added to add 70 parts by weight. The polymerization reaction was carried out at 3 ° C. for 3 hours.

After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 12 having a weight average molecular weight of 300,000 and a weight average molecular weight / number average molecular weight of 20.
[Production Example 13]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 23 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) And 160 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

  Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 2 hours in a nitrogen atmosphere. Further, 0.2 part by weight of azobisisobutyronitrile was further added to add 70 parts by weight. The polymerization reaction was carried out at 3 ° C. for 3 hours.

After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 13 having a weight average molecular weight of 30,000 and a weight average molecular weight / number average molecular weight of 20.
[Production Example 14]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 23 parts by weight of butyl acrylate (BA), 70 parts by weight of methoxyethyl acrylate (MEA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Part, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

  Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 2 hours under a nitrogen atmosphere. Further, 0.2 part by weight of azobisisobutyronitrile was further added to add 70 parts by weight. The polymerization reaction was carried out at 3 ° C. for 3 hours.

After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 14 having a weight average molecular weight of 500,000 and a weight average molecular weight / number average molecular weight of 20.
[Production Example 15]
A reactor equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen introduction tube was charged with 95 parts by weight of methyl methacrylate (BA), 5 parts by weight of dimethylaminoethyl acrylate (DM), 100 parts by weight of ethyl acetate (EtAc) and methyl ethyl ketone ( MEK) 20 parts by weight was charged, and the temperature was raised to 85 ° C. while introducing nitrogen gas.

Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction solution was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a low molecular weight product having a weight average molecular weight of 10,000.
[Example 1]
Takenate D-110N (manufactured by Mitsui Chemicals), 0.6 parts by weight (solid content), which is a trimethylolpropane adduct type xylylene diisocyanate as a crosslinking agent, relative to 100 parts by weight of the acrylic polymer 1 obtained in Production Example 1. Were mixed to obtain a pressure-sensitive adhesive composition.

The obtained pressure-sensitive adhesive composition was coated on a peeled polyethylene terephthalate (PET) film so that the thickness after drying was 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, and pressure-sensitive adhesive. A layer was formed. The peeled PET film is attached to the surface of the adhesive layer that is in contact with the PET film, and aged for 7 days in an environment of 23 ° C. and 65% to obtain an adhesive sheet (adhesive thickness 50 μm). It was.
[Example 2]
An adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of acrylic polymer 2 was used instead of 100 parts by weight of acrylic polymer 1 and the amount of Takenate D-110N was 0.5 parts by weight.
[Example 3]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of acrylic polymer 3 was used instead of 100 parts by weight of acrylic polymer 1 and the amount of Takenate D-110N was 0.7 parts by weight.
[Example 4]
Except for using an adhesive composition in which 100 parts by weight of acrylic polymer 1 0.6 parts by weight of Takenate D-110N and 5 parts by weight of the low molecular weight product obtained in Production Example 15 were used, the same procedure as in Example 1 was performed. An adhesive sheet was obtained.
[Example 5]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of acrylic polymer 4 was used instead of 100 parts by weight of acrylic polymer 1 and the amount of Takenate D-110N was 1 part by weight.
[Example 6]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of acrylic polymer 5 was used instead of 100 parts by weight of acrylic polymer 1.
[Example 7]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of acrylic polymer 6 was used instead of 100 parts by weight of acrylic polymer 1.
[Example 8]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of the acrylic polymer 7 was used instead of 100 parts by weight of the acrylic polymer 1.
[Example 9]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of acrylic polymer 8 was used instead of 100 parts by weight of acrylic polymer 1.
[Comparative Example 1]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of acrylic polymer 9 was used instead of 100 parts by weight of acrylic polymer 1.
[Comparative Example 2]
An adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of the acrylic polymer 10 was used instead of 100 parts by weight of the acrylic polymer 1 and the amount of Takenate D-110N was 0.5 parts by weight.
[Comparative Example 3]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of the acrylic polymer 11 was used instead of 100 parts by weight of the acrylic polymer 1 and the amount of Takenate D-110N was 0.8 parts by weight.
[Comparative Example 4]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of the acrylic polymer 12 was used instead of 100 parts by weight of the acrylic polymer 1.
[Comparative Example 5]
An adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of the acrylic polymer 13 was used instead of 100 parts by weight of the acrylic polymer 1 and the amount of Takenate D-110N was 1 part by weight.

Regarding the evaluation of foaming in Table 1, “impossible to evaluate” means that the sheet shape could not be maintained after coating and drying.
[Comparative Example 6]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 100 parts by weight of acrylic polymer 14 was used instead of 100 parts by weight of acrylic polymer 1.

表１中の略号は以下の通りである。
ＢＡ・・・ブチルアクリレート
ＭＥＡ・・・メトキシエチルアクリレート
２−ＨＥＡ・・・２−ヒドロキシエチルアクリレート
ＡＡ・・・アクリル酸
ＤＭ・・・ジメチルアミノエチルメタクリレート
ＡＭ・・・アクリルアミド
Ｄ−１１０Ｎ・・・キシリレンジイソシアネートのトリメチロールプロパン付加体（三井化学社製）
また、Ｍｗの単位は万であり、段差粘着力の単位は（Ｎ／２５ｍｍ）である。重合に用いられる全モノマーを１００重量部とする。

Abbreviations in Table 1 are as follows.
BA ... butyl acrylate MEA ... methoxyethyl acrylate 2-HEA ... 2-hydroxyethyl acrylate AA ... acrylic acid DM ... dimethylaminoethyl methacrylate AM ... acrylamide D-110N ... xyly Trimethylolpropane adduct of range isocyanate (Mitsui Chemicals)
Moreover, the unit of Mw is 10,000, and the unit of the step adhesive force is (N / 25 mm). The total monomer used for the polymerization is 100 parts by weight.

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 69 ... polymer particle 70 ... adhesive layer 71 ... Frame printing part

Claims (14)

A laminate in which a base material, an adhesive layer, and a conductive layer are laminated in this order,
The pressure-sensitive adhesive layer is
(A) a (meth) acrylic polymer having substantially no acidic group, a weight average molecular weight of 50,000 or more and less than 400,000, and a molecular weight distribution of 10 or more and 40 or less;
(B) including an isocyanate-based crosslinking agent,
The (meth) acrylic polymer (A) is at least one selected from the group consisting of alkoxyalkyl (meth) acrylates and alkoxypolyalkylene glycol mono (meth) acrylates (a-1) 20 to 99.5% by weight; A monomer containing 0.5 to 10% by weight of a monomer (a-2) having a hydroxyl group and 0 to 5% by weight of a nitrogen-containing monomer (a-3) (total monomer is 100% by weight) is copolymerized. A laminate obtained by being obtained.   The (meth) acrylic polymer (A) is obtained by copolymerizing a monomer containing 0.1 to 4% by weight of a nitrogen-containing monomer (a-3) (with all monomers being 100% by weight). The laminate according to claim 1, wherein the laminate is characterized in that: At least one (a-1) selected from the group consisting of the alkoxyalkyl (meth) acrylate and alkoxypolyalkylene glycol mono (meth) acrylate is at least one selected from the group consisting of methoxyethyl acrylate and methoxydiethylene glycol acrylate The laminate according to claim 1 or 2 , wherein the laminate is provided.   The pressure-sensitive adhesive layer substantially contains an acidic group obtained by copolymerizing a monomer containing 0.1 to 20% by weight of (C) nitrogen-containing (meth) acrylate (with 100% by weight of all monomers). 1 to 10 parts by weight of a (meth) acrylic low molecular weight body having a weight average molecular weight of 5,000 or more and less than 50,000 is contained per 100 parts by weight of the (meth) acrylic polymer (A). The laminate according to any one of claims 1 to 3.   The laminate according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer has a gel fraction of 50 to 70%.   The laminated body according to any one of claims 1 to 5, wherein the conductive layer is a transparent conductive film made of a metal or a metal oxide.   The thickness of the said adhesive layer is 10-1000 micrometers, The laminated body as described in any one of Claims 1-6 characterized by the above-mentioned. In a touch panel comprising a surface support, a pressure-sensitive adhesive layer, and a touch panel unit including a laminate in which a conductive layer is laminated in this order, and a display laminated on the touch panel unit,
The said laminated body is a laminated body as described in any one of Claims 1-7, The touch panel characterized by the above-mentioned.   The touch panel according to claim 8, wherein the touch panel is a capacitive touch panel.   10. The touch panel according to claim 8, wherein in the laminated body, frame printing is performed on an edge portion of a surface of the surface support that faces the pressure-sensitive adhesive layer.   The thickness of the said frame printing exists in the range of 10-50 micrometers, The touch panel of Claim 10 characterized by the above-mentioned.   12. The conductive layer is a circuit pattern using ITO and / or ATO as a metal oxide, and the adhesive layer is in direct contact with the circuit pattern. The touch panel according to any one of the above.   The thickness of the said surface support body exists in the range of 25-2000 micrometers, The touchscreen in any one of Claims 8-12 characterized by the above-mentioned. The touch panel according to paragraph 12 claims, characterized in that the thickness of the circuit pattern which is the conductive layer is in the range of 10 to 100 nm.

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