JP5841867B2 - Touch panel member sticking adhesive, touch panel member sticking adhesive sheet, and touch panel device - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive for sticking a touch panel member, a pressure-sensitive adhesive sheet for sticking a touch panel member having the pressure-sensitive adhesive, and a touch panel device using the pressure-sensitive adhesive sheet.

  The capacitive touch panel is made of a laminate composed of various members such as a glass plate used as a top panel, a hard coat layer, and a transparent conductive film on an LCD module. In order to bond the various members of these touch panels, for example, an adhesive as disclosed in Patent Document 1 is used.

By the way, when a weak voltage is applied to the transparent conductive film, the capacitive touch panel accumulates charges on the surface of the transparent conductive film and forms an electric field. When the surface of the touch panel is contacted with a conductor such as a finger or a touch pen, the state of the formed electric field is changed and discharged, and a weak current flows. And the detection of a contact position can be performed by calculating this weak change in current flowing in the four corners of the transparent conductive film.
Thus, the detection sensitivity of the capacitive touch panel depends on the magnitude of the change in the electric field. Therefore, as a laminate material constituting the capacitive touch panel, a high capacitance material that easily forms an electric field is required.
Here, the capacitance can be expressed by the following calculation formula (1). As can be seen from the calculation formula (1), in order to obtain a high electrostatic capacity, two means of thinning the material and improving the dielectric constant can be considered.

(In the above formula, C: capacitance [F], ε ₀ : vacuum permittivity [F / m], ε _r : relative permittivity [−], S: area [m ² ], d: thickness [m ]

JP 2002-363523 A

In recent years, with the weight reduction of touch panels, the use of plastic plates and plastic films as a substitute for glass plates used as top panels has been studied. However, since the relative permittivity of plastic is lower than that of glass, there is a concern that the sensitivity of the touch panel is lowered. That is, while the relative dielectric constant of glass is about 6 to 8, the relative dielectric constant of polymethyl methacrylate (PMMA), which is a common plastic as a top panel, is 3.0 to 3.7. The relative dielectric constant of polycarbonate (PC) is 2.9 to 3.0.
Therefore, when the material of the touch panel member is changed from glass to plastic, there is a problem in that the relative permittivity is lowered and the reactivity and sensitivity are lowered due to the decrease in capacitance.
Moreover, the relative dielectric constant of the pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive as described in Patent Document 1 is about 5, and the presence of the pressure-sensitive adhesive layer made of such a pressure-sensitive adhesive is also a factor of lowering the capacitance. It becomes.
Although it is possible to increase the capacitance by reducing the thickness of the touch panel member, it is difficult to appropriately change the thickness of the touch panel member due to the design and manufacturing problems of the touch panel.

  In addition, the performance of the touch panel is important not only for the value of relative dielectric constant related to sensitivity but also for the value of dielectric loss tangent. The dielectric loss tangent is a factor related to the performance as a capacitor of the touch panel, for example, S / N ratio, linearity, power consumption, etc. It can be said that the lower the value of the dielectric loss tangent, the better the performance as a capacitor. It is also known that the value of dielectric loss tangent rises by replacing the glass with plastic as the material of the touch panel member and by providing the adhesive layer made of acrylic adhesive in the construction of the touch panel. The decrease in performance is also a problem.

  Even when plastic is used instead of glass as the material of the touch panel member, the present invention has a high relative dielectric constant and dielectric so that it can be a touch panel having high capacitance, excellent sensitivity, and excellent capacitor performance. An object is to provide a pressure-sensitive adhesive for sticking a touch panel member, which can form a pressure-sensitive adhesive layer having a low tangent, a pressure-sensitive adhesive sheet for a touch panel member having a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive, and a touch panel device using the pressure-sensitive adhesive sheet. And

As a result of intensive studies, the present inventors have found that a pressure-sensitive adhesive containing a (meth) acrylic acid ester copolymer containing a specific structural unit at a specific ratio and a cross-linking agent can solve the above problems. The present invention was completed.
That is, the present invention provides the following [1] to [12].
[1] A pressure-sensitive adhesive for sticking a touch panel member containing a (meth) acrylic acid ester copolymer (A) and a crosslinking agent (B),
The (meth) acrylic acid ester copolymer (A) contains 19 to 92% by mass of the structural unit (a1) derived from the alkyl (meth) acrylate monomer (a1) having an alkyl group having 4 to 20 carbon atoms, the following general formula: Copolymer comprising 7 to 80% by mass of the structural unit (a2) derived from the alkoxyalkyl (meth) acrylate monomer (a2) represented by (1) and the structural unit (a3) derived from the functional group-containing monomer (a3) An adhesive for sticking a touch panel member, which is a coalescence.
[In the formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents a linear or branched alkylene group having 1 to 5 carbon atoms, and R ³ represents a linear chain having 1 to 8 carbon atoms. Or a branched alkyl group is shown. However, the total number of carbon atoms of R ² and R ³ is 4 or more. The value of n is an integer of 1 or more. ]
[2] The adhesive for sticking a touch panel member according to the above [1], wherein the value of n in the general formula (1) is an integer of 2 to 12.
[3] The pressure-sensitive adhesive for sticking a touch panel member according to the above [1] or [2], wherein the alkoxyalkyl (meth) acrylate monomer (a2) is ethoxydiethylene glycol (meth) acrylate or methoxytriethylene glycol (meth) acrylate .
[4] The content of the structural unit (a3) derived from the functional group-containing monomer (a3) is 0.01 to 15% by mass with respect to all the structural units of the (meth) acrylic acid ester copolymer (A). The adhesive for sticking a touch panel member according to any one of [1] to [3].
[5] The above [1] to [4], wherein the content of the crosslinking agent (B) is 0.01 to 15 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). The adhesive for a touch panel member sticking in any one of.
[6] A pressure-sensitive adhesive sheet for sticking a touch panel member, having a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive for sticking a touch panel member according to any one of [1] to [5].
[7] The pressure-sensitive adhesive sheet for sticking a touch panel member according to the above [6], which has the pressure-sensitive adhesive layer on a substrate.
[8] The pressure-sensitive adhesive sheet for attaching a touch panel member according to [7], wherein the base material is a plastic plate or a plastic film.
[9] The adhesive sheet for sticking a touch panel member according to any one of the above [6] to [8], wherein the adhesive layer has a relative dielectric constant at a frequency of 1 MHz of 6.00 or more.
[10] A touch panel device using the adhesive sheet for attaching a touch panel member according to any one of [6] to [9].
[11] The touch panel device according to [10], wherein the touch panel device is a capacitive type.

  The pressure-sensitive adhesive for sticking a touch panel member of the present invention can form a pressure-sensitive adhesive layer having a high relative dielectric constant and a low dielectric loss tangent. Therefore, the touch panel device of the present invention using the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer has high capacitance, excellent sensitivity, and excellent capacitor performance even when plastic is used instead of glass as the material of the touch panel member. It can be a touch panel.

It is sectional drawing of the adhesive sheet which is the 1st aspect of the adhesive sheet for touchscreen member sticking of this invention. It is sectional drawing of the adhesive sheet which is a 2nd aspect of the adhesive sheet for touchscreen member sticking of this invention. It is sectional drawing of the measurement sample used for the measurement of a dielectric constant and the dielectric loss tangent in a present Example.

[Adhesive for sticking touch panel members]
The pressure-sensitive adhesive for sticking a touch panel member of the present invention (hereinafter also simply referred to as “pressure-sensitive adhesive”) contains a (meth) acrylic acid ester copolymer (A) and a crosslinking agent (B). Moreover, the adhesive of this invention may contain other additives other than (A) and (B) component. Hereinafter, each component contained in the pressure-sensitive adhesive of the present invention will be described.
In the following description, for example, “(meth) acrylic acid” means both acrylic acid and methacrylic acid, and the same applies to other similar terms.

[(A) component: (meth) acrylic acid ester copolymer (A)]
In the pressure-sensitive adhesive of the present invention, as the component (A), a structural unit derived from an alkyl (meth) acrylate monomer (a1) having an alkyl group having 4 to 20 carbon atoms (hereinafter also referred to as “monomer (a1)”) ( The structural unit (a2) derived from 19 to 92% by mass of a1) and the alkoxyalkyl (meth) acrylate monomer (a2) represented by the general formula (1) (hereinafter also referred to as “monomer (a2)”) is 7 to (Meth) acrylic acid ester copolymer containing 80 mass% and the structural unit (a3) derived from the functional group-containing monomer (a3) (hereinafter also referred to as “monomer (a3)”).
In the present invention, the component (A) may be used alone or in combination of two or more.

The weight average molecular weight (Mw) of the (meth) acrylic acid ester copolymer (A) is preferably 250,000 to 1,500,000, more preferably 350,000 to 1,300,000, still more preferably 450,000 to 1,100,000, and even more preferably. Is 650,000-950,000.
When the weight average molecular weight is 250,000 or more, the durability of the pressure-sensitive adhesive is improved, it is difficult for floating and peeling, and foaming is difficult to occur even in a high temperature and high humidity environment. On the other hand, if it is 1.5 million or less, polymerization at the time of polymer synthesis can be easily performed.
In the present invention, the weight average molecular weight (Mw) is a standard polystyrene equivalent value measured by a gel permeation chromatography (GPC) method.
Hereinafter, each structural unit contained in the (meth) acrylic acid ester copolymer (A) will be described.

(Structural unit (a1))
The (meth) acrylic acid ester copolymer (A) contains 19 to 92% by mass of a structural unit (a1) derived from an alkyl (meth) acrylate monomer (a1) having an alkyl group having 4 to 20 carbon atoms as a structural unit. Including. By including a specific amount of the structural unit (a1) in the copolymer of the component (A), an appropriate adhesive force can be obtained as an adhesive sheet.

The number of carbon atoms of the alkyl group of the monomer (a1) is 4 to 20, preferably 4 to 12, more preferably 4 to 8, still more preferably 4 to 6, and still more preferably 4 or 5.
When the carbon number of the alkyl group is less than 4, a pressure-sensitive adhesive layer having a sufficiently increased relative dielectric constant cannot be formed from the pressure-sensitive adhesive obtained, and a decrease in capacitance becomes a problem. Moreover, since the adhesive force of an adhesive is not fully expressed, it is not preferable.
On the other hand, when the carbon number of the alkyl group exceeds 20, the dielectric constant of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive can be increased, but the dielectric loss tangent of the pressure-sensitive adhesive layer also increases, and the pressure-sensitive adhesive A touch panel having a layer is not preferable because of poor capacitor performance.

  Although the alkyl group of the monomer (a1) may be either linear or branched, from the viewpoint of obtaining a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having a reduced dielectric loss tangent while maintaining a high relative dielectric constant. A linear alkyl group is preferred.

Examples of the monomer (a1) include n-butyl (meth) acrylate, butyl (meth) acrylate such as isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Examples include isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like.
Among these, butyl (meth) acrylate, pentyl (meth) acrylate, and hexyl (meth) acrylate are preferable from the viewpoint of obtaining a pressure sensitive adhesive capable of forming a pressure sensitive adhesive layer having a high relative dielectric constant and a low dielectric loss tangent, and n -Butyl (meth) acrylate is more preferred.
In addition, you may use these monomers (a1) individually or in combination of 2 or more types.

Although content of a structural unit (a1) is 19-92 mass% in all the structural units of a (meth) acrylic acid ester copolymer (A), Preferably it is 30-80 mass%, More preferably, it is 35-35 mass%. It is 70 mass%, More preferably, it is 47-63 mass%.
If it is less than 19% by mass, it causes a decrease in adhesive strength. On the other hand, when it exceeds 92% by mass, the content of the structural unit (a2) other than the structural unit (a1) cannot be sufficiently ensured, and the relative dielectric constant of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive is particularly high. Since it falls, it is not preferable.

(Structural unit (a2))
(Meth) acrylic acid ester copolymer (A) is 7-80 masses of structural units (a2) derived from the alkoxyalkyl (meth) acrylate monomer (a2) represented by the following general formula (1) as structural units. % Is included. By including a specific amount of the structural unit (a2) in the copolymer (A), it is possible to increase the relative dielectric constant of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive and simultaneously decrease the dielectric loss tangent.

In the general formula (1), R ¹ represents a hydrogen atom or a methyl group.
R ² represents a linear or branched alkylene group having 1 to 5 carbon atoms, preferably a linear or branched alkylene group having 2 to 5 carbon atoms, more preferably a straight chain having 2 to 3 carbon atoms. It is a chain or branched alkylene group, more preferably a linear alkylene group having 2 to 3 carbon atoms.
Examples of the linear or branched alkylene group having 1 to 5 carbon atoms represented by R ² include a methylene group, an ethylene group, a propylene group, an isopropylene group, a 1,4-butylene group, a 1,3-butylene group, A tetramethylene group, a 1,5-pentylene group, a 1,4-pentylene group, a 1,3-pentylene group and the like can be mentioned.

R ³ represents a linear or branched alkyl group having 1 to 8 carbon atoms, preferably a linear or branched alkyl group having 1 to 4 carbon atoms, more preferably a straight chain having 1 to 3 carbon atoms. Chain alkyl group.
Examples of the linear or branched alkyl group having 1 to 8 carbon atoms represented by R ³ include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, and a pentyl group. Hexyl group, heptyl group, octyl group and the like.

  In the general formula (1), the value n represents the number of repeating units of the alkylene oxide chain and is an integer of 1 or more. The value of n is preferably an integer of 2 to 12, more preferably an integer of 3 to 9, and still more preferably an integer of 4 to 7. By using a monomer having such a value, the obtained adhesive can effectively reduce the dielectric loss tangent while maintaining a high relative dielectric constant.

Incidentally, the total number of carbon atoms of R ² and R ³ are 4 or more, preferably 5 to 20, more preferably 6 to 18, more preferably from 7 to 15. When the total number of carbon atoms is 4 or more, an adhesive layer in which the dielectric loss tangent is effectively reduced can be formed from the obtained adhesive while maintaining a high relative dielectric constant.
In the compound represented by the general formula (1), when the number of carbon atoms per group represented by R ² is A and the number of carbon atoms of the group represented by R ³ is B, The “total number of carbon atoms of R ² and R ³ ” can be expressed as A × n + B (pieces).
For example, the total number of carbon atoms in ethoxydiethylene glycol acrylate is 6 (= 2 × 2 + 2), and the total number of carbon atoms in methoxytriethylene glycol acrylate is 7 (= 2 × 3 + 1).

Among the above monomers (a2), ethoxydiethylene glycol (meth) acrylate or methoxytriethylene glycol (meth) acrylate is preferable, and methoxytriethylene glycol (meth) acrylate is more preferable.
In addition, you may use these monomers (a2) individually or in combination of 2 or more types.

Although content of a structural unit (a2) is 7-80 mass% in all the structural units of a (meth) acrylic acid ester copolymer (A), Preferably it is 20-70 mass%, More preferably, it is 28- It is 63 mass%, More preferably, it is 33-56 mass%.
If it is less than 7% by mass, the relative dielectric constant of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive obtained in particular is unfavorable. On the other hand, if it exceeds 80% by mass, the content of the structural unit (a1) other than the structural unit (a2) cannot be sufficiently secured, which causes a decrease in adhesive strength.

(Structural unit (a3))
The (meth) acrylic acid ester copolymer (A) contains a functional group-containing monomer (a3) as a structural unit. By including the structural unit (a3) in the copolymer (A), the cohesive force is maintained, and an adhesive layer having excellent adhesive force can be formed.
The “functional group” of the “functional group-containing monomer” here means a functional group that reacts with the cross-linking agent (B) to become a cross-linking origin or a functional group having a cross-linking promoting effect.
Examples of the functional group include a hydroxyl group, a carboxy group, an amide group, an amino group, an epoxy group, a cyano group, a keto group, and a nitrogen element-containing ring. Among these, a carboxy group or a hydroxyl group is preferable from the viewpoint of reactivity with the crosslinking agent (B).

  Examples of the monomer (a3) include ethylenically unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid and fumaric acid; 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meta ) Acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate and other hydroxyalkyl ester (meth) acrylates; monomethylamino Monoalkylaminoalkyl (meth) acrylates such as ethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, etc. And the like.

Among these, from the viewpoint of reactivity with the crosslinking agent (B), ethylenically unsaturated carboxylic acid and hydroxyalkyl (meth) acrylate are preferable, and (meth) acrylic acid and 4-hydroxybutyl (meth) acrylate are more preferable. .
In addition, you may use these monomers (a3) individually or in combination of 2 or more types.

  The content of the structural unit (a3) is preferably 0.01 to 15% by mass, more preferably 0.1 to 10% by mass in all the structural units of the (meth) acrylic acid ester copolymer (A). Preferably it is 0.5-4 mass%. When the content is 0.01% by mass or more, the resulting pressure-sensitive adhesive does not decrease in cohesive force and can exhibit excellent pressure-sensitive adhesive force. On the other hand, if it is 15 mass% or less, since the easiness of preparation of an adhesive solution and the raise of the viscosity at the time of apply | coating can be suppressed, it is preferable.

In addition, as a structural unit in the (meth) acrylic acid ester copolymer (A), for the purpose of controlling the adhesive force control and the cohesive force of the obtained pressure-sensitive adhesive, the above structural unit is within the range not impairing the effects of the present invention. Other structural units derived from monomers other than (a1) to (a3) may be included.
The content of structural units derived from other monomers is preferably 0 to 10% by mass, more preferably 0 to 4% by mass, and still more preferably in all the structural units of the (meth) acrylic acid ester copolymer (A). It is substantially 0% by mass (not substantially contained).

[Crosslinking agent (B)]
A crosslinking agent (B) bridge | crosslinks a (meth) acrylic acid ester copolymer (A).
Examples of the crosslinking agent used include organic polyvalent isocyanate compounds, organic polyvalent epoxy compounds, organic polyvalent imine compounds, and metal chelate compounds. Among these, an organic polyvalent isocyanate compound and a metal chelate compound are preferable from the viewpoints of increasing the cohesive force of the obtained pressure-sensitive adhesive and improving the pressure-sensitive adhesive force and availability.

Examples of the organic polyvalent isocyanate compound include tolylene diisocyanate compounds such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate; 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and the like. Xylylene diisocyanate compounds; diphenylmethane-4,4′-diisocyanate, diphenylmethane-2,4′-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, dicyclohexylmethane— 2,4'-diisocyanate, lysine isocyanate, etc. are mentioned.
In addition, trimers of these organic polyvalent isocyanate compounds, terminal isocyanate urethane prepolymers obtained by reacting these organic polyvalent isocyanate compounds and polyol compounds, and the like can also be used.

  Examples of organic polyvalent epoxy compounds include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, 1,3-bis (N, N-diglycidylaminomethyl) toluene, N, N, N ′, N′-tetra. Examples include glycidyl-4,4-diaminodiphenylmethane.

  Examples of the organic polyvalent imine compound include N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane- Examples include tri-β-aziridinylpropionate, N, N′-toluene-2,4-bis (1-aziridinecarboxamide) triethylenemelamine, and the like.

  Examples of the metal chelate compound include coordination compounds of polyvalent metals such as aluminum chelate compounds such as trisethyl acetoacetate aluminum, ethyl acetoacetate aluminum diisopropylate, and trisacetylacetonate aluminum.

In addition, you may use these crosslinking agents (B) individually or in combination of 2 or more types.
The content of the crosslinking agent (B) is preferably 0.01 to 15 parts by mass (solid content ratio), more preferably 0.1 to 100 parts by weight of the (meth) acrylic acid ester copolymer (A). It is -8 mass parts (solid content ratio), More preferably, it is 0.2-4 mass parts (solid content ratio). If it is 0.01 mass part (solid content ratio) or more, cohesive force sufficient to maintain the shape against the stress in the shearing direction can be obtained. On the other hand, if it is 15 mass parts (solid content ratio) or less, sufficient adhesive force is obtained.

[Other additives]
Moreover, you may make the adhesive of this invention contain another additive in the grade which does not impair the effect of this invention as needed. Examples of additives include tackifiers, ultraviolet absorbers, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, and the like that are conventionally used in adhesives.

Examples of the tackifier include known tackifiers, and hydrogenated petroleum resins are preferable.
Examples of hydrogenated petroleum resins include hydrogenated terpene resins, hydrogenated rosins and hydrogenated rosin ester resins, disproportionated rosins, disproportionated rosin ester resins, pentenes generated by thermal decomposition of petroleum naphtha, and isoprene. Hydrogenated dicyclopentadiene resin, partially hydrogenated aromatic modified dicyclopentadiene resin, petroleum naphtha, which is a hydrogenated resin of C5 petroleum resin obtained by copolymerizing C5 fraction such as 1.3-pentadiene Resin obtained by hydrogenation of C9 petroleum resin obtained by copolymerizing C9 fraction such as indene, vinyltoluene, α- or β-methylstyrene produced by thermal decomposition of C5, C9 fraction and C9 fraction Examples thereof include a resin obtained by hydrogenating a copolymer petroleum resin.

Examples of the UV absorber include hindered amine UV absorbers, benzotriazole UV absorbers, oxazolyac acid amide compounds, benzophenone UV absorbers, and triazine UV absorbers.
Examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, vitamin antioxidants, lactone antioxidants, amine antioxidants, and the like.
Examples of the softening agent (plasticizer) include liquid polyether, glycol ester, liquid polyterpene, liquid polyacrylate, phthalic acid ester, trimellitic acid ester, and the like.

The pressure-sensitive adhesive of the present invention may be further diluted with an organic solvent to form a pressure-sensitive adhesive solution in order to facilitate application to a substrate and the like described later and improve workability.
Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol. As these organic solvents, the organic solvents used in the preparation of the components (A) and (B) may be used as they are, or the organic solvents used in the preparation so that the adhesive solution can be uniformly applied. One or more organic solvents other than may be added.

  As solid content concentration of an adhesive solution, Preferably it is 10-60 mass%, More preferably, it is 10-45 mass%, More preferably, it is 15-30 mass%. If it is 10% by mass or more, the amount of the solvent used is sufficient, and if it is 60% by mass or less, the viscosity becomes appropriate and the coating operation becomes easy.

[Adhesive sheet for pasting touch panel members]
The pressure-sensitive adhesive sheet for sticking a touch panel member of the present invention (hereinafter also simply referred to as “pressure-sensitive adhesive sheet”) has a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive for sticking a touch panel member of the present invention described above.
Although the structure of the adhesive sheet of this invention is not specifically limited, For example, the adhesive sheet of the aspect of FIG.
The pressure-sensitive adhesive sheet 1 shown in FIG. 1 is a double-sided pressure-sensitive adhesive sheet without a substrate, in which release sheets 12a and 12b are laminated on both surfaces of a pressure-sensitive adhesive layer 11.
As the release sheet, both a release sheet subjected to double-sided release treatment and a release sheet subjected to release treatment only on one side are used. The release sheet is obtained by applying a release agent to one side or both sides of the release sheet substrate.

Examples of the release sheet base material include polyethylene terephthalate, polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polybutylene terephthalate, polyurethane, ethylene-vinyl acetate copolymer, ionomer. Resin, ethylene (meth) acrylic acid copolymer, polystyrene, polycarbonate, fluororesin, low-density polyethylene, linear low-density polyethylene, resin film such as triacetyl cellulose; fine paper, coated paper, glassine paper, laminated paper, etc. A paper base material etc. are mentioned.
Examples of the release agent to be used include silicone resins, olefin resins, long chain alkyl resins, alkyd resins, fluorine resins, rubber elastomers such as isoprene resins and butadiene resins.
Although there is no restriction | limiting in particular in the thickness of a peeling sheet, Preferably it is 5-300 micrometers, More preferably, it is 10-200 micrometers. In addition, when using a polyethylene terephthalate-type film as a base material for peeling sheets, it is preferably 10-100 micrometers.

  When it is set as the form of a double-sided adhesive sheet without a substrate as shown in FIG. 1, it is preferable to use a heavy release sheet and a light release sheet having a difference in peeling force as the release sheets 12a and 12b. By using two release sheets that have a difference in peel force, when only the light release sheet side is peeled off, the adhesive layer may float from the heavy release sheet side, or the adhesive layer cannot be peeled off from both release sheets. The fear of being stretched and deformed can be prevented.

  The production method of the double-sided pressure-sensitive adhesive sheet without a substrate is not particularly limited. For example, after the pressure-sensitive adhesive solution is directly applied to the surface of one release sheet and dried to form a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer Another release sheet can be attached to the top. As described above, as the release sheet, it is preferable to use a heavy release sheet and a light release sheet having a difference in release force. In this case, it is preferable that the pressure-sensitive adhesive solution is directly applied to the surface of the heavy release sheet and dried to form a pressure-sensitive adhesive layer, and then a light release sheet is bonded onto the pressure-sensitive adhesive layer.

Moreover, the adhesive sheet of this invention may have an adhesive layer in at least one surface of a base material like FIG. As such an embodiment, as shown in FIG. 2A, the single-sided pressure-sensitive adhesive sheet 2a with the base material 13 having the pressure-sensitive adhesive layer 11 formed on one side thereof, or the base as shown in FIG. Examples thereof include a double-sided pressure-sensitive adhesive sheet 2b with a base material having pressure-sensitive adhesive layers 11a and 11b on both surfaces of the material 13. Moreover, the above-mentioned peeling sheet may be further laminated | stacked on the adhesive layer of these adhesive sheets with a base material.
In addition, when it is set as the double-sided adhesive sheet with a base material, it is preferable to use the adhesive of this invention on both surfaces, However, Two types of adhesives from which a material differs may be laminated | stacked on a base material. In this case, the pressure-sensitive adhesive of the present invention can be applied to one pressure-sensitive adhesive. Moreover, when a certain amount of thickness is required for a double-sided adhesive sheet, the total thickness of a double-sided adhesive sheet with a base material can be easily adjusted by adjusting suitably with the thickness of a base material.

  Although it does not specifically limit as the base material 13, For example, a polyethylene terephthalate, a polyethylene naphthalate, a polyimide, polyetherimide, polyaramid, polyetherketone, polyetheretherketone, polyphenylene sulfide, poly (4-methylpentene-1) Polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polyethylene terephthalate, polyurethane, ethylene-vinyl acetate copolymer, ionomer resin, ethylene (meth) acrylic acid copolymer, polystyrene, Plastic plates or plastic films such as polycarbonate, fluororesin, low density polyethylene, linear low density polyethylene, triacetyl cellulose; glass substrates .

  In the pressure-sensitive adhesive sheet of the present invention, a plastic plate or a plastic film is used as a base material, and a pressure-sensitive adhesive layer is formed on the base material, whereby the pressure-sensitive adhesive layer has a high relative dielectric constant and a dielectric loss tangent. Since it is low, the dielectric constant of the whole adhesive sheet including the base material of a plastic plate or a plastic film can be raised, and a dielectric loss tangent can be lowered. Also from the viewpoint of weight reduction, the substrate is preferably a plastic plate or a plastic film.

  Although the thickness of a base material is selected suitably, Preferably it is 5-300 micrometers, More preferably, it is 10-100 micrometers.

  The method for producing the double-sided pressure-sensitive adhesive sheet with a substrate is not particularly limited. For example, 2 pressure-sensitive adhesive sheets with a release sheet in which a pressure-sensitive adhesive solution is directly applied on the above-described release sheet and dried to form a pressure-sensitive adhesive layer. A sheet is prepared, and the adhesive layer of the two adhesive sheets with a release sheet can be prepared by sticking to both surfaces of a separately prepared substrate. Alternatively, the adhesive solution may be directly applied to both surfaces of the substrate and dried to form an adhesive layer, and then a release sheet may be bonded to the adhesive layer, or one of the substrates The pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet without a substrate can be bonded onto the surface, and the pressure-sensitive adhesive solution can be directly applied onto the other surface of the substrate and dried to form a pressure-sensitive adhesive layer.

  Although there is no restriction | limiting in particular also as a manufacturing method of the single-sided adhesive sheet with a base material, For example, it can produce by bonding the adhesive layer of the above-mentioned double-sided adhesive sheet without a base material on one surface of a base material. . Alternatively, the pressure-sensitive adhesive solution may be directly applied on one surface of the substrate and dried to form a pressure-sensitive adhesive layer, and then a release sheet may be bonded to the pressure-sensitive adhesive layer.

  As a method of applying a pressure-sensitive adhesive solution containing the pressure-sensitive adhesive of the present invention to a release sheet or a substrate, a known method can be used, for example, a gravure coating method, a bar coating method, a spray coating method, a spin coating method, Examples thereof include a roll coating method, a die coating method, a knife coating method, an air knife coating method, and a curtain coating method. In addition, after apply | coating an adhesive solution, it is preferable to heat and dry for about 30 seconds-5 minutes at the temperature of about 80 to 150 degreeC from a viewpoint of preventing the residue of a solvent and a low boiling point component.

The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is preferably 1 to 200 μm, more preferably 5 to 100 μm, still more preferably 10 to 60 μm in the case of a double-sided pressure-sensitive adhesive sheet after drying. If the thickness is 1 μm or more, sufficient adhesive performance can be obtained. On the other hand, when the thickness is 200 μm or less, it is possible to prevent the pressure-sensitive adhesive layer from protruding.
In the case of a single-sided pressure-sensitive adhesive sheet with a substrate, the thickness is preferably 1 to 195 μm, more preferably 5 to 100 μm, and still more preferably 10 to 60 μm.
In the case of a double-sided pressure-sensitive adhesive sheet with a substrate, the thickness of each pressure-sensitive adhesive layer is preferably 1 to 195 μm, more preferably 5 to 100 μm, and still more preferably 10 to 60 μm.

The relative dielectric constant at a frequency of 1 MHz of the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive of the present invention is preferably 6.00 or more, more preferably 7.00 or more, still more preferably 8.00 or more, and still more preferably 8. 50 or more.
In addition, the value of the dielectric constant at a frequency of 1 MHz of the pressure-sensitive adhesive layer means a value measured by the method described in the examples.

[Touch panel device]
As described above, the pressure-sensitive adhesive for sticking a touch panel member of the present invention can form a pressure-sensitive adhesive layer having a high relative dielectric constant and a low dielectric loss tangent.
Therefore, the touch panel device using the pressure-sensitive adhesive sheet of the present invention having a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive for pasting various members of the touch panel, even when using plastic instead of glass as the material of the touch panel member, A touch panel with high capacitance, excellent sensitivity, and excellent capacitor performance can be obtained. In particular, this effect is significant when the touch panel device is a capacitive touch panel.
Therefore, since the member which used glass conventionally can be replaced with plastic, the touch panel device reduced in weight can be obtained.

The following examples of the present invention will be described more specifically, but the present invention is not limited to these examples.
[Example 1]
As the component (A), an acrylic acid ester copolymer (BA / EDG-A / 4HBA = 58.) Comprising n-butyl acrylate (BA), ethoxydiethylene glycol acrylate (EDG-A), and 4-hydroxybutyl acrylate (4HBA). 2 / 40.0 / 1.8 (mass%), Mw = 800,000, solid content concentration 39.4 mass%) 100 parts by mass (solid content), and (B) component as a tolylene diisocyanate crosslinking agent ( Made by Nippon Polyurethane Industry Co., Ltd., trade name “Coronate L”, solid content 75%) 1.71 parts by mass (solid content ratio), mixed and diluted with methyl ethyl ketone to give a solid content concentration of 25% by mass A solution was prepared.
The prepared pressure-sensitive adhesive solution is applied on the release-treated surface of a heavy release sheet (product name “SP-PET382150”, thickness: 38 μm, manufactured by Lintec Corporation) so that the film thickness after drying is 25 μm. A film was formed, and the coating film was dried at 120 ° C. for 2 minutes to form an adhesive layer. And the base material which bonded the peeling process surface of the light release sheet (the product name "SP-PET382120", thickness: 38 micrometers) by the Lintec company) on the surface of this adhesive layer, and was pinched | interposed into two release films A double-sided PSA sheet was obtained.

[Example 2]
As the component (A), acrylic acid ester copolymer (BA / MTG-A / 4HBA = n-butyl acrylate (BA), methoxytriethylene glycol acrylate (MTG-A), 4-hydroxybutyl acrylate (4HBA) = Except for using 100 parts by mass (solid content) of 58.2 / 40.0 / 1.8 (mass%), Mw = 800,000, solid content concentration of 39.4 mass%), the same as in Example 1. A double-sided pressure-sensitive adhesive sheet without a substrate was obtained.

[Comparative Example 1]
As the component (A), an acrylic acid ester copolymer (BA / MEA / 4HBA = 58.2 / 40.n) composed of n-butyl acrylate (BA), methoxyethyl acrylate (MEA), and 4-hydroxybutyl acrylate (4HBA). 100 parts by mass (solid content) of 0 / 1.8 (mass%), Mw = 800,000, solid content concentration 37.2 mass%), and 1.81 parts by mass (solid content) of component (B) Except for the ratio, a double-sided PSA sheet without a substrate was obtained in the same manner as in Example 1.

[Comparative Example 2]
As component (A), acrylic acid ester copolymer consisting of n-butyl acrylate (BA) and acrylic acid (AA) (BA / AA = 90.0 / 10.0 (mass%), Mw = 600,000, solid In the same manner as in Example 1, except that 100 parts by mass (solid content) of 33.6% by mass) was used, and the blending amount of component (B) was 2.23 parts by mass (solid content ratio). A material-free double-sided PSA sheet was obtained.

[Comparative Example 3]
As component (A), acrylic acid ester copolymer consisting of n-butyl acrylate (BA) and acrylic acid (AA) (BA / AA = 95.0 / 5.0 (mass%), Mw = 600,000, solid In the same manner as in Example 1, except that 100 parts by mass (solid content) of 100% by mass (solid content) was used and the amount of component (B) was 1.96 parts by mass (solid content ratio). A material-free double-sided PSA sheet was obtained.

[Comparative Example 4]
As the component (A), an acrylic ester copolymer (BA / MA / HEA = 79.0 / 20.0) composed of n-butyl acrylate (BA), methyl acrylate (MA), and 2-hydroxyethyl acrylate (HEA). /1.0 (mass%), Mw = 800,000, solid content concentration 35.1 mass%) is used at 100 mass parts (solid content), and the blending amount of component (B) is 0.96 mass parts (solid content ratio). Except for the above, a double-sided PSA sheet without a substrate was obtained in the same manner as in Example 1.

[Comparative Example 5]
As the component (A), an acrylic ester copolymer (BA / MA / AA = 78.2 / 20.0 / 1.n) composed of n-butyl acrylate (BA), methyl acrylate (MA), and acrylic acid (AA). 8 (mass%), Mw = 800,000, solid content concentration 32.2 mass%) was used at 100 mass parts (solid content), and the amount of component (B) was 2.33 mass parts (solid content ratio). Except for this, a baseless double-sided PSA sheet was obtained in the same manner as Example 1.

[Comparative Example 6]
As the component (A), an acrylic ester copolymer (BA / MA / AA = 77.0 / 20.0 / 3.n) composed of n-butyl acrylate (BA), methyl acrylate (MA), and acrylic acid (AA). 100 parts by mass (solid content) of 0 (mass%), Mw = 800,000, solid content concentration 35.1% by mass, and as component (B), a tolylene diisocyanate crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product) Name “Coronate L”, solid concentration 75% by mass) 2.34 parts by mass (solid content ratio) and aluminum chelate-based crosslinking agent (manufactured by Soken Chemical Co., Ltd., trade name “M-5A”, solid content concentration 4.95 mass) %) 0.31 part by mass (solid content ratio), mixed, diluted with methyl ethyl ketone, and prepared in the same manner as in Example 1, except that a pressure-sensitive adhesive solution with a solid content concentration of 25% was used. Double-sided adhesive sheet without substrate It was.

  With respect to the double-sided pressure-sensitive adhesive sheet produced as described above, the relative dielectric constant and dielectric loss tangent of the pressure-sensitive adhesive layer were measured based on the following method. The measured results are shown in Table 1.

[Measurement of relative permittivity]
Two layers prepared by peeling off one release film of the baseless double-sided PSA sheet prepared in Examples and Comparative Examples, laminating the PSA layers, and two PSA layers were laminated The sheet | seat with an adhesive layer laminated body which consists of was obtained. Further, two sheets of the two-layered sheet with the pressure-sensitive adhesive layer laminate were prepared by peeling off one release film, and similarly laminated to form four pressure-sensitive adhesive layers. A sheet with a layered laminate was obtained.
Both peeled films of the four-layered sheet with the resulting pressure-sensitive adhesive layer laminate were peeled off, and a polyethylene terephthalate film (trade name “Lumirror T-60”, manufactured by Toray Industries, Inc.) having a thickness of 50 μm was used and shown in FIG. Thus, the both sides of 11 A of adhesive layer laminated bodies with which the 4 layers of adhesive layers 11 were laminated | stacked were pinched | interposed with the said 2 polyethylene terephthalate films 51a and 51b, and the measurement sample was produced. In addition, the constant-pressure thickness meter (the product name "PG-02" by a teclock company) was used for the measurement of the thickness of an adhesive layer.
Then, an “Agilent 16451B Dielectric Test Fixture” (product name, manufactured by Agilent Technologies) is connected to the LCR / resistance meter (product name “Impedance / Gain Phase Analyzer 4194A” manufactured by Agilent Technologies), and the frequency The capacitance C ₁ (unit: F) of the measurement sample at 1 MHz was measured.
Separately measure the capacitance of the 50 μm polyethylene terephthalate films 51a and 51b (the measured value is C ₂ (unit: F)), and calculate the capacitance C ₃ (unit: F) of the pressure-sensitive adhesive layer laminate 11A. It calculated from the following calculation formula (2).

The capacitance C ₃ (unit: F) of the pressure-sensitive adhesive layer laminate 11A calculated from the above formula (2), the thickness d (unit: m) of the pressure-sensitive adhesive layer laminate 11A, and the diameter L = 0 of the measurement electrode 0.005 (unit: m), vacuum permittivity ε ₀ = 8.854 × 10 ⁻¹² (unit: F / m), relative permittivity ε _{r of the} adhesive layer (adhesive layer laminate 11A) Was derived by the following calculation formula (3).

The value of the dielectric constant ε _r of the pressure-sensitive adhesive layer calculated from the above formula (3) was evaluated according to the following criteria.
A: The value of the dielectric constant ε _r is 7.00 or more.
B: The value of the relative dielectric constant ε _r is 6.00 or more and less than 7.00.
C: The value of the relative dielectric constant ε _r is less than 6.00.

[Measurement of dielectric loss tangent]
Using the measurement sample prepared in the above “measurement of relative dielectric constant”, an LCR / resistance meter (product name “impedance / gain phase analyzer 4194A” manufactured by Agilent Technologies, Inc.) is used for “Agilent 16451B dielectric test test”. A “fixture” (product name, manufactured by Agilent Technologies) was connected, and the dielectric loss tangent of the measurement sample at a frequency of 1 MHz was measured. In addition, the said measured value is a value of the dielectric loss tangent of the laminated body of a measurement sample, and is not the value of an adhesive layer simple substance.

The measured dielectric loss tangent value was evaluated according to the following criteria.
A: The value of dielectric loss tangent is less than 0.035.
B: The value of dielectric loss tangent is 0.035 or more and less than 0.040.
C: The value of dielectric loss tangent is 0.040 or more.

  From the results in Table 1, it can be seen that the pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets of Examples 1 and 2 have a high relative dielectric constant and a low dielectric loss tangent. On the other hand, a satisfactory result was not obtained for both the relative dielectric constant and dielectric loss tangent of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets of Comparative Examples 1-6.

  The adhesive for sticking a touch panel member of the present invention is particularly useful as an adhesive for attaching a constituent member of a capacitive touch panel.

1, 2a, 2b Adhesive sheets 11, 11a, 11b Adhesive layer 11A Adhesive layer laminate 12a, 12b Release sheet 13 Base materials 51a, 51b Polyethylene terephthalate film

Claims (11)

A pressure-sensitive adhesive for sticking a touch panel member comprising a (meth) acrylic acid ester copolymer (A) having a weight average molecular weight of 450,000 to 1,500,000 and a crosslinking agent (B),
The (meth) acrylic acid ester copolymer (A) contains 19 to 92% by mass of the structural unit (a1) derived from the alkyl (meth) acrylate monomer (a1) having an alkyl group having 4 to 20 carbon atoms, the following general formula: Copolymer comprising 7 to 80% by mass of the structural unit (a2) derived from the alkoxyalkyl (meth) acrylate monomer (a2) represented by (1) and the structural unit (a3) derived from the functional group-containing monomer (a3) An adhesive for sticking a touch panel member, which is a coalescence.

[In Formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents a linear or branched alkylene group having 1 to 5 carbon atoms, and R ³ represents a linear chain having 1 to 8 carbon atoms. Or a branched alkyl group is shown. However, ( the carbon number of R ² ) × n + ( the carbon number of R ³ ) is 4 or more. Moreover, the value of n is an integer of 2-12 . ] The adhesive for sticking a touch panel member according to claim 1 , wherein the alkoxyalkyl (meth) acrylate monomer (a2) is ethoxydiethylene glycol (meth) acrylate or methoxytriethylene glycol (meth) acrylate. Content of a structural unit (a3) derived from a functional group containing monomer (a3) is 0.01-15 mass% with respect to all the structural units of a (meth) acrylic acid ester copolymer (A), Item 3. The adhesive for sticking a touch panel member according to item 1 or 2 . The content of the crosslinking agent (B) is (meth) acrylic acid ester copolymer (A) with respect to 100 parts by weight, 0.01 to 15 parts by weight, of any of claims 1-3 Adhesive for sticking touch panel members. A pressure-sensitive adhesive sheet for sticking a touch panel member, comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive for sticking a touch panel member according to any one of claims 1 to 4 . The pressure-sensitive adhesive sheet for attaching a touch panel member according to claim 5 , wherein the pressure-sensitive adhesive layer is provided on a base material. The pressure-sensitive adhesive sheet for sticking a touch panel member according to claim 6 , wherein the substrate is a plastic plate or a plastic film. The adhesive sheet for sticking a touch panel member according to any one of claims 5 to 7 , wherein a relative dielectric constant of the adhesive layer at a frequency of 1 MHz is 6.00 or more. The adhesive sheet for a touch panel member sticking in any one of Claims 5-8 whose dielectric loss tangent in the frequency of 1 MHz of the said adhesive layer is less than 0.04. A touch panel device using the pressure-sensitive adhesive sheet for attaching a touch panel member according to claim 5 .   The touch panel device according to claim 10, wherein the touch panel device is a capacitive type.