TWI645009B - Laminated adhesive sheets and laminated bodies - Google Patents

Abstract

The problem of the present invention is to find a method for controlling the relative permittivity more accurately, and to provide an adhesive sheet whose relative permittivity is controlled by the control method. The invention relates to a laminated adhesive sheet, which is characterized in that it has at least a first adhesive layer and a second adhesive layer, and the relative dielectric properties of the first adhesive layer and the second adhesive layer at a frequency of 1 MHz. The absolute value of the difference between the constants is 0.5 or more. Furthermore, the present invention relates to a laminated adhesive sheet, which is characterized by a first adhesive layer having a relative dielectric constant of 4 or less at a frequency of 1 MHz and a second adhesive layer having a relative dielectric constant of 4 or more at a frequency of 1 MHz.剂 层。 The agent layer.

Description

Laminated adhesive sheet and laminated body

The invention relates to a laminated adhesive sheet and a laminated body. Specifically, the present invention relates to a laminated adhesive sheet having a controlled relative dielectric constant, and is a laminated adhesive sheet capable of exhibiting desired adhesiveness.

In recent years, a display device such as a liquid crystal display (LCD) or an input device used in combination with a display device such as a touch panel has been widely used in various fields. When manufacturing such display devices or input devices, use transparent double-sided adhesive sheets for the purpose of bonding optical components, and also use transparent double-sided adhesive sheets (for example, patents) when bonding display devices and input devices. References 1 to 3).

In such a display device or an input device, various functions such as an adhesive property and an insulation property are required for the adhesive sheet. For example, Patent Document 4 discloses a multi-layer type adhesive sheet having a different dielectric constant. Furthermore, Patent Document 5 discloses a single-layer type adhesive sheet having a specific dielectric constant or a dielectric loss tangent. It is proposed to improve the operation performance of the touch panel by controlling the dielectric constant of the adhesive sheet.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2003-238915

[Patent Document 2] Japanese Patent Laid-Open No. 2003-342542

[Patent Document 3] Japanese Patent Laid-Open No. 2004-231723

[Patent Document 4] Japanese Patent No. 4093355

[Patent Document 5] International Publication No. 2010/147047

As described above, it is required to control the dielectric constant of the adhesive sheet to a specific range according to the performance required for a display device or an input device. However, the relative permittivity is a property value inherent in a substance, so it is not easy to control it with good accuracy, and it is required to find a method for controlling the relative permittivity more accurately.

Therefore, in order to solve such a problem of the prior art, the inventors have found a method of controlling the relative dielectric constant more accurately, and provided an adhesive sheet whose relative dielectric constant is controlled by the control method. Advance research.

The present inventors conducted intensive research in order to solve the above-mentioned problems, and as a result, found that in a laminated adhesive sheet having at least a first adhesive layer and a second adhesive layer, the relative dielectric constant and thickness of the first adhesive layer The relative dielectric constant and thickness of the second adhesive layer are adjusted in such a way as to become a specific condition, whereby the relative dielectric constant of the laminated adhesive sheet can be adjusted. In this way, the present inventors have succeeded in obtaining a laminated adhesive sheet with a controlled relative dielectric constant, thereby completing the present invention.

Specifically, this invention has the following structures.

[1] A laminated adhesive sheet, which is characterized in that it has at least a first adhesive layer and a second adhesive layer, and the relative frequency between the first adhesive layer and the second adhesive layer at a frequency of 1 MHz The absolute value of the difference between the electric constants is 0.5 or more.

[2] The laminated adhesive sheet according to [1], which has at least a first adhesive layer and a second adhesive layer, and has a first adhesive layer with a relative dielectric constant of less than 4 at a frequency of 1 MHz, and The second adhesive layer having a relative dielectric constant of 4 or more at a frequency of 1 MHz.

[3] The laminated adhesive sheet according to [1] or [3], wherein the frequency of the first adhesive layer is 1 MHz The relative permittivity below does not reach 3.

[4] The laminated adhesive sheet according to any one of [1] to [3], wherein the thickness of each of the first adhesive layer and the second adhesive layer is 10 μm or more.

[5] The laminated adhesive sheet according to any one of [1] to [4], wherein a ratio of the thickness of the first adhesive layer to the second adhesive layer is 1:99 to 99: 1.

[6] The laminated adhesive sheet according to any one of [1] to [5], wherein the first adhesive layer and the second adhesive layer are acrylic adhesive layers.

[7] The laminated adhesive sheet according to any one of [1] to [6], wherein the first adhesive layer and the second adhesive layer include a (meth) acrylate.

[8] The laminated adhesive sheet according to any one of [1] to [7], which further has a third adhesive layer.

[9] The laminated adhesive sheet according to any one of [1] to [8], which further has a resin layer.

[10] The laminated adhesive sheet according to [9], wherein the resin layer is provided between the first adhesive layer and the second adhesive layer.

[11] The laminated adhesive sheet according to [9], wherein the first adhesive layer is laminated on the resin layer, and the second adhesive layer is laminated on the side opposite to the resin layer via the first adhesive layer. .

[12] The laminated adhesive sheet according to any one of [9] to [11], wherein the relative dielectric constant of the resin layer at a frequency of 1 MHz is 2 to 10.

[13] A laminated body formed by bonding the laminated adhesive sheet according to any one of [1] to [12] to at least one optical member.

[14] The laminated body according to [13], wherein at least one of the optical members is ITO (Indium Tin Oxides) glass or ITO film.

[15] A relative dielectric constant adjustment method, characterized in that it is a method for adjusting the relative dielectric constant of a laminated adhesive sheet having at least two adhesive layers, and the laminated adhesive sheet has a relative dielectric constant at a frequency of 1 MHz First adhesive layer with constant less than 4 and frequency The second adhesive layer having a relative dielectric constant of 1 or more at 1 MHz is 4 or more. By adjusting the relative dielectric constant and thickness of the first adhesive layer at 1 MHz, the relative dielectric constant and thickness of the second adhesive layer at 1 MHz are adjusted. Dielectric constant and thickness, and adjust the relative dielectric constant of the laminated adhesive sheet.

[16] The relative dielectric constant adjustment method according to [15], wherein the relative dielectric constant and thickness of the first adhesive layer at a frequency of 1 MHz, and the relative dielectric constant of the second adhesive layer at a frequency of 1 MHz And thickness are adjusted using the following formula (1),

(In formula (1), ε represents the relative dielectric constant of the entire laminated adhesive sheet, d represents the thickness of the entire laminated adhesive sheet; and ε _n represents the relative dielectric constant of each adhesive layer, and d _n represents each adhesive layer Thickness; furthermore, n represents the number of layers of the adhesive layer).

[17] The relative dielectric constant adjustment method according to [16], wherein in the above formula (1), d ₁ to d _n are determined so as to become a specific ε under the condition that ε ₁ to ε _n are fixed.

[18] The relative permittivity adjustment method according to [16], wherein in the above formula (1), ε ₁ and ε _n- are determined to be specific ε under the condition that ε _n and d _n are fixed. _1. With d ₁ ~ d _n-1 .

[19] The relative dielectric constant adjustment method according to any one of [16] to [18], wherein n is 2 in the above formula (1).

[20] A method for manufacturing a laminated adhesive sheet, which is characterized in that it is a method for producing a laminated adhesive sheet having at least two adhesive layers, and through the relative introduction of any one of [16] to [19] The dielectric constant adjustment method adjusts the relative dielectric constant of the laminated adhesive sheet.

According to the present invention, a method for more accurately controlling the relative permittivity in a laminated adhesive sheet can be provided. Therefore, in the present invention, a laminated adhesive sheet having a desired relative dielectric constant can be obtained. In addition, in the present invention, the relative dielectric constant in the laminated adhesive sheet can be accurately controlled, so the production efficiency of the laminated adhesive sheet can be improved, and the detailed requirements required when manufacturing the laminated body can be met.

1‧‧‧ the first adhesive layer

2‧‧‧ 2nd adhesive layer

3‧‧‧ the third adhesive layer

5‧‧‧ resin layer

10‧‧‧ laminated adhesive sheet

1 (a) to (d) are schematic cross-sectional views of a laminated adhesive sheet according to the present invention.

2 (a) and (b) are schematic cross-sectional views showing another aspect of the laminated adhesive sheet of the present invention.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below is completed based on a representative embodiment or a specific example, but the present invention is not limited to such an embodiment. In addition, in this specification, a numerical range indicated by "~" means a range including numerical values described before and after "~" as a lower limit value and an upper limit value.

(Laminated Adhesive Sheet)

The present invention relates to a laminated adhesive sheet having at least a first adhesive layer and a second adhesive layer. In the multilayer adhesive sheet of the present invention, the absolute value of the relative dielectric constant difference between the first adhesive layer and the second adhesive layer at a frequency of 1 MHz is 0.5 or more. The relative dielectric constant of the first adhesive layer of the laminated adhesive sheet of the present invention at a frequency of 1 MHz is preferably less than 4, and the relative dielectric constant of the second adhesive layer at a frequency of 1 MHz is 4 or more. Furthermore, the laminated adhesive sheet of the present invention can function as a double-sided adhesive sheet having at least a first adhesive layer and a second adhesive layer.

1 (a)-(d) are schematic cross-sectional views of a laminated adhesive sheet 10 according to the present invention. As shown in FIGS. 1 (a) to (c), the laminated adhesive sheet 10 includes a first adhesive layer 1 and a second adhesive layer 2. In FIGS. 1 (a) to (c), the laminated adhesive sheet 10 includes only the first adhesive layer 1 and the second adhesive layer 2, but may also have other functional layers or adhesive layers. For example, as shown in FIG. 1 (d), the laminated adhesive sheet 10 of the present invention may have a third adhesive layer in addition to the first adhesive layer 1 and the second adhesive layer 2. 胶 胶剂 层 3。 Adhesive layer 3. Furthermore, when the laminated adhesive sheet 10 has a functional layer other than the adhesive layer, at least any one of the first adhesive layer 1, the second adhesive layer 2 and the third adhesive layer 3 is disposed on Outermost.

In the laminated adhesive sheet of the present invention, the absolute value of the difference between the relative dielectric constants of the first adhesive layer and the second adhesive layer is 0.5 or more. The absolute value of the difference between the relative dielectric constants of the first adhesive layer and the second adhesive layer is preferably 1 or more, more preferably 2 or more. By adjusting the relative dielectric constant difference between the first adhesive layer and the second adhesive layer to the range described above, the relative permittivity of the laminated adhesive sheet can be easily adjusted, and the laminated layer can be adjusted with good accuracy. Relative permittivity of the adhesive sheet.

In the present invention, the relative dielectric constant of the first adhesive layer at a frequency of 1 MHz is preferably less than 4, more preferably less than 3, even more preferably less than 2.5, and even more preferably less than 2. By setting the relative dielectric constant of the first adhesive layer at a frequency of 1 MHz to be within the above range, the relative dielectric constant of the entire laminated adhesive sheet can be further efficiently controlled. In addition, the relative permittivity of the entire laminated adhesive sheet can be suppressed to be low.

The relative dielectric constant of the second adhesive layer at a frequency of 1 MHz is preferably 4 or more, more preferably 4.5 or more, still more preferably 5 or more, and still more preferably 5.5 or more. The relative dielectric constant of the first adhesive layer at a frequency of 1 MHz and the relative dielectric constant of the second adhesive layer at a frequency of 1 MHz can be set to a specific range, and the relative dielectric constant of the entire laminated adhesive sheet can be controlled .

The relative dielectric constant (ε) in the present invention can be obtained by a method specified in JIS-C-2138.

The thickness ratio of the first adhesive layer and the second adhesive layer is preferably 1:99 to 99: 1. By adjusting the thickness of the first adhesive layer and the second adhesive layer in this way, the relative dielectric constant of the entire laminated adhesive sheet can be controlled.

In the laminated adhesive sheet of the present invention, the relative permittivity of the entire laminated adhesive sheet can be controlled by setting the first adhesive layer and the second adhesive layer under specific conditions. Specifically and In other words, the relative dielectric constant of the laminated adhesive sheet can be controlled by adjusting the relative dielectric constant and thickness of the first adhesive layer and the relative dielectric constant and thickness of the second adhesive layer, respectively.

In the present invention, the relative permittivity and thickness of the first adhesive layer and the relative permittivity and thickness of the second adhesive layer can be adjusted using the following formula (1).

Here, in formula (1), ε represents the relative dielectric constant of the entire laminated adhesive sheet, and d represents the thickness of the entire laminated adhesive sheet. In addition, ε _n represents the relative dielectric constant of each adhesive layer, and d _n represents the thickness of each adhesive layer. In addition, n represents the number of layers of the adhesive layer.

In the present invention, when forming a laminated adhesive sheet having a specific relative dielectric constant, the above-mentioned formula (1) can be used to calculate the relative dielectric constant and thickness of the first adhesive layer, and the relative dielectric constant and thickness of the second adhesive layer. Relative dielectric constant and thickness. That is, if the relative dielectric constant required for the laminated adhesive sheet is determined and the thickness of the laminated adhesive sheet is determined, the relative dielectric constant and thickness of the first adhesive layer and the second adhesive layer can be calculated.

In the present invention, specifically, it is preferable to adjust the dielectric constant under the conditions described below. For example, in the above-mentioned formula (1), d ₁ to d _n may be determined so as to become a specific ε under the condition that ε ₁ to ε _n are fixed. In the above formula (1), ε ₁ to ε _n-1 and d ₁ to d _n-1 can be determined under the condition that ε _n and d _n are fixed.

By setting the conditions in accordance with the appearance of the laminated adhesive sheet, the above formula (1) can be used to select an adhesive having the adhesive physical properties of the adherend, and form a laminated adhesive sheet having the required relative dielectric constant. .

Furthermore, in the present invention, in the formula (1), n is preferably 2 to 6, more preferably 2 to 4, and even more preferably 2 or 3. By using the above formula (1), two layers can be easily adjusted. The relative dielectric constant of the laminated adhesive sheet of the above adhesive layer.

The laminated adhesive sheet of the present invention may have a third adhesive layer. In the case where the laminated adhesive sheet has a third adhesive layer, the third adhesive layer may be an adhesive layer having the same relative dielectric constant as the first adhesive layer or the second adhesive layer which are not adjacent to each other, or may be It is an adhesive layer which has the same relative dielectric constant as the adjacent 1st adhesive layer or 2nd adhesive layer. That is, the third adhesive layer may have the same relative permittivity as the adjacent adhesive layer, or may have a different relative permittivity. When the first adhesive layer, the second adhesive layer, and the third adhesive layer are sequentially stacked, the relative dielectric constants of the first adhesive layer and the third adhesive layer may be the same.

The third adhesive layer may be an adhesive layer having a relative dielectric constant different from that of either the first adhesive layer or the second adhesive layer. When the laminated adhesive sheet has a third adhesive layer, the absolute value of the difference between the relative dielectric constant of the third adhesive layer and the relative permittivity of the adjacent first adhesive layer or the second adhesive layer is smaller. It is preferably 0.5 or more, more preferably 1 or more, and even more preferably 2 or more. Furthermore, it is preferable that the absolute value of the relative dielectric constant difference between all the adhesive layers is within the above range. That is, the absolute value of the difference between the relative permittivity of the first adhesive layer and the relative permittivity of the second adhesive layer is preferably within the above range, and the relative permittivity of the second adhesive layer and The absolute value of the difference between the relative dielectric constants of the third adhesive layer is within the above range, and the absolute value of the difference between the relative dielectric constants of the first adhesive layer and the third adhesive layer is preferably within the above range.

When the laminate composed of an adhesive sheet having a case are more than three layers layer of adhesive, in the above formula (1), also in [epsilon] ₁ and ε _n, d ₁ and d _n is fixed the condition to decide ε ₂ ~ ε _{n -1} and d ₂ to d _n-1 . In this case, a laminated adhesive sheet having a desired relative permittivity can be formed by adjusting the relative dielectric constant and thickness of the adhesive layer existing on the inner side of the laminated adhesive sheet.

That is, in the case of a laminated adhesive sheet in which n is 3 or more, it can be set in advance as having an adhesive layer (hereinafter, referred to as the outermost adhesive layer) to be adhered to the adherend. The proper adhesive properties and thickness of the adhesive body can be obtained by using the above formula (1) to set the dielectric constant of the entire laminated adhesive sheet to the desired outermost adhesive layer. The thickness of the layer. Thereby, a laminated adhesive sheet can be obtained that can simultaneously achieve the required adhesive physical properties and dielectric constant.

The thickness of each of the first adhesive layer and the second adhesive layer of the laminated adhesive sheet of the present invention is preferably 10 μm or more. If it is more than the said lower limit value, the relative dielectric constant of the whole laminated adhesive sheet can be adjusted with high precision. The thickness of the entire laminated adhesive sheet is preferably 20 to 1000 μm, especially the thickness of the outermost adhesive layer is preferably 10 to 100 μm, and more preferably 25 to 50 μm. By adjusting the thickness of the outermost adhesive layer within the above-mentioned range, it is made into a laminated adhesive sheet having the adhesive physical properties of the adherend. When the laminated adhesive sheet of the present invention has a third adhesive layer, the thickness of the third adhesive layer is also preferably within the above range.

Thus, the present invention is a method for adjusting the relative dielectric constant of a laminated adhesive sheet having at least two adhesive layers, and is a method for adjusting the relative dielectric constant of the above formula (1). By using the relative dielectric constant adjustment method of the present invention, a laminated adhesive sheet having various relative dielectric constants can be easily formed. Thereby, the relative dielectric constant of the entire laminated adhesive sheet can be accurately controlled.

Furthermore, the present invention also relates to a method for manufacturing a laminated adhesive sheet having at least two adhesive layers, and includes adjusting the relative dielectric constant of the laminated adhesive sheet by using the relative dielectric constant adjustment method of the above formula (1). A method for manufacturing a laminated adhesive sheet in the steps. It is also possible to improve the production efficiency of the laminated adhesive sheet by using this manufacturing method.

(Adhesive)

As an adhesion main agent for forming the first adhesive layer and the second adhesive layer, in order not to reduce visibility of a display device or the like, it is preferable to use one having transparency. For example, a known adhesive such as an acrylic adhesive, a silicone adhesive, a polyester adhesive, a rubber adhesive, a polyurethane adhesive, or the like can be used. Among them, it is preferable to use acrylic adhesive. The agent is preferably an acrylic adhesive containing an acrylic polymer as a base polymer.

<Acrylic polymer>

The acrylic polymer contains a non-crosslinkable (meth) acrylate unit and an acrylic monomer unit having a crosslinkable functional group. Here, the "monomer unit" is a repeating unit constituting a polymer. The "acrylic monomer" is a compound having a (meth) acrylfluorenyl group. "(Meth) acrylfluorenyl" means acrylfluorenyl or methacrylfluorenyl. The non-crosslinkable acrylic monomer is an acrylic monomer having no crosslinkable group, and the crosslinkable monomer is a monomer having a crosslinkable group. As long as a crosslinkable monomer is polymerizable with a non-crosslinkable acrylic monomer, it may be an acrylic monomer or a non-acrylic monomer, and an acrylic monomer is preferable. Examples of the crosslinkable group include a carboxyl group, a hydroxyl group, an amine group, an epoxy group, and a glycidyl group.

Examples of the non-crosslinkable acrylic monomer unit include a (meth) acrylic acid ester unit in which a hydrogen atom of a carboxyl group of (meth) acrylic acid is replaced with a hydrocarbon group. In the present invention, each adhesive layer preferably contains a (meth) acrylate unit.

The carbon number of the hydrocarbon group in the (meth) acrylate unit is preferably 1 to 18, and more preferably 1 to 8. The hydrocarbon group may have a substituent. The substituent is not particularly limited as long as it does not contain a crosslinkable group, and examples thereof include alkoxy groups such as a methoxy group and an ethoxy group.

Specific examples of the (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and (methyl) N-butyl acrylate, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, n-amyl (meth) acrylate, n-hexyl (meth) acrylate, (meth) acrylic acid 2- Ethylhexyl, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, iso- (meth) acrylate Ester, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-undecyl (meth) acrylate, n-dodecane (meth) acrylate Ester, stearyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate . Among these, in terms of adhesiveness, n-butyl acrylate, 2-ethylhexyl acrylate, and methyl acrylate are preferably used. These can be used alone or in combination of two or more. Furthermore, in the present invention, "(meth) acrylic acid" means both "acrylic acid" and "methacrylic acid".

Examples of the crosslinkable monomer unit include a carboxyl group-containing copolymerizable monomer unit, a hydroxyl group-containing copolymerizable monomer unit, an amine group-containing copolymerizable monomer unit, and a glycidyl group-containing copolymerizable monomer unit. Examples of the carboxyl group-containing copolymerizable monomer include acrylic acid, methacrylic acid, butene acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and glutaric acid. β-unsaturated carboxylic acid or anhydride thereof.

Examples of the hydroxy-containing copolymerizable monomer include (meth) groups such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxypropyl (meth) acrylate. (Meth) acrylic acid [(mono, di or poly) alkylene glycol], (meth) acrylic acid mono (diethylene glycol), etc. (Meth) acrylate.

Examples of the amine-group-containing copolymerizable monomer include (meth) acrylamide, allylamine, and the like.

Examples of the glycidyl group-containing copolymerizable monomer include glycidyl (meth) acrylate and the like.

Among these, in terms of adhesion, crosslinkability, and polymerizability, and further less corrosiveness of metals such as tin-doped indium oxide used for transparent conductive films or copper used for electromagnetic wave masks, The hydroxyl-containing copolymerizable monomer is more preferably a hydroxyalkyl (meth) acrylate, more preferably 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate.

In addition, when a carboxyl group-containing copolymerizable monomer unit is included as a crosslinkable monomer unit, the acidity becomes strong. Therefore, if it comes into contact with a corrosive film such as a tin-doped indium oxide film or a metal film, it will corrode the Isometric conditions. Therefore, in terms of corrosion resistance, when a carboxyl group-containing copolymerizable monomer unit is included as a crosslinkable monomer unit, the content ratio is preferably less than 0.5% by mass, and more preferably no content at all. . Also, as a laminated adhesive sheet In terms of corrosion resistance, the content of the carboxyl-containing copolymerizable monomer unit in the acrylic polymer is preferably not more than 1.0% by mass.

The acrylic polymer may have other monomer units other than the crosslinkable acrylic monomer unit and the crosslinkable monomer unit. Examples of other monomers include (meth) acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinylpyrrolidone, and vinylpyridine.

The content of other monomer units in the acrylic polymer is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass. If the content rate of the other monomer units is equal to or more than the above-mentioned lower limit value, physical properties can be easily adjusted. When the content rate of the other monomer units is equal to or less than the above-mentioned upper limit value, yellowing due to deterioration with time can be prevented.

The relative dielectric constant of each adhesive layer can be set to a desired value by appropriately selecting the type of resin used for the adhesive. For example, in the case of increasing the relative dielectric constant, it is preferable to use a (meth) acrylic acid ester unit having a relatively high polarity, such as (meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, and (meth) acrylic acid. Propyl ester, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, third butyl (meth) acrylate, and the like. Among them, methyl (meth) acrylate and n-butyl (meth) acrylate are preferred from the viewpoints of transparency and adhesion between the first adhesive layer and the second adhesive layer.

In addition, as the crosslinkable monomer unit, similarly, it is only necessary to use a carboxyl group-containing copolymerizable monomer unit, a hydroxyl group-containing copolymerizable monomer unit, and an amine group-containing copolymerizable monomer unit having relatively high polarity. Examples of the copolymerizable monomers of a carboxyl group include acrylic acid, methacrylic acid, butenoic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and glutaric acid. Unsaturated carboxylic acid or its anhydride, as a hydroxyl-containing copolymerizable monomer, for example, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2- (meth) acrylate 2- Hydroxyalkyl (meth) acrylates such as hydroxypropyl esters, (meth) acrylic acid ((mono, di, or poly) alkylene glycols) such as (meth) acrylic acid mono (diethylene glycol), (methyl (Meth) acrylic lactones such as monocaprolactone, etc., as the copolymerizable monomer containing an amine group, for example: Group) acrylamide, allylamine and the like. Among them, from the viewpoint of the ease of controlling the relative dielectric constant, the polarity is based on the fact that the ratio of the molecule as a whole is increased. Therefore, 2-hydroxyethyl (meth) acrylate and 4-hydroxy (meth) acrylate are preferred. Hydroxybutyl ester.

On the other hand, in the case where the relative dielectric constant of the adhesive layer is reduced, it is only necessary to use the one having a lower polarity. Examples include 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isonon (meth) acrylate Ester, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-undecyl (meth) acrylate, n-dodecyl (meth) acrylate, hard (meth) acrylate Aliphatic ester, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl acrylate or isopropyl acrylate Among alicyclic compounds such as esters, (meth) acrylic acid is preferred from the viewpoint of transparency or adhesiveness of the adhesive layer, and from the viewpoint of achieving a relative dielectric constant of less than 4. 2-ethylhexyl ester, (meth) acrylic acid iso ester.

<Crosslinking agent>

A cross-linking agent may also be used in each adhesive layer. Examples of the crosslinking agent include isocyanate compounds, epoxy compounds, An oxazoline compound, an aziridine compound, a metal chelate compound, a butylated melamine compound, and the like. Among these crosslinking agents, an isocyanate compound and an epoxy compound are preferred because they can easily crosslink an acrylic polymer. In particular, when the acrylic polymer contains only a copolymerizable monomer unit containing a hydroxyl group as a crosslinkable monomer unit, it is preferable to use an isocyanate compound in terms of the reactivity of the hydroxyl group.

Examples of the isocyanate compound include toluene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol diglycidyl ether, and neopentyl glycol diethylene glycol. Glycidyl ether, 1,6-hexanediol diglycidyl ether, tetraglycidyl xylylenediamine, 1,3-bis (N, N-diglycidylamine methyl) cyclohexane, trimethylol C Alkyl polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, and the like. The content of the cross-linking agent is preferably appropriately selected depending on the desired adhesive properties.

[additive]

Further, each of the adhesive layers may contain other additives such as light stabilizers such as antioxidants, anti-corrosive agents, adhesion-imparting agents, silane coupling agents, ultraviolet absorbers, hindered amine compounds, and fillers as necessary.

Examples of the antioxidant include a phenol-based antioxidant, an amine-based antioxidant, a lactone-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant. These antioxidants may be used individually by 1 type, and may use 2 or more types together.

As the anti-corrosive agent, a benzotriazole-based resin is preferred in terms of the compatibility of the adhesive or the height of the effect.

Examples of the adhesion-imparting agent include a rosin-based resin, a terpene-based resin, a terpene-based resin, a lavender-indene-based resin, a styrene-based resin, a xylene-based resin, a phenol-based resin, and a petroleum resin.

Examples of the silane coupling agent include a mercaptoalkoxysilane compound (for example, an alkoxy oligomer substituted with a mercapto group).

Examples of the ultraviolet absorber include benzotriazole-based compounds and benzophenone-based compounds.

(Resin layer)

The laminated adhesive sheet of the present invention may have a resin layer in addition to the above-mentioned first adhesive layer, second adhesive layer, and third adhesive layer. The resin layer may be an adhesive layer or a non-adhesive resin layer. It may be a single layer or a plurality of layers. In the case where the resin layer is a non-adhesive resin layer, the resin to be used is preferably one that does not affect the optical properties. Examples include polycarbonate, polyethylene terephthalate, and polymethylmethacrylate. Methyl acrylate, polyethylene naphthalate, cycloolefin polymer, triethyl cellulose, Polyimide, tritiated cellulose, etc.

In the case where the resin layer is an adhesive layer, the adhesive main agent is the same as the adhesive main agent used for each adhesive layer, and is preferably one having a degree of transparency that does not reduce the visibility of the display device. For example, known adhesives such as acrylic adhesives, silicone adhesives, polyester adhesives, rubber adhesives, and polyurethane adhesives can be used, especially from the viewpoint of durability. It is preferably an acrylic adhesive containing an acrylic polymer containing an alkyl (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms as a main monomer component as a base polymer.

FIG. 2 is a schematic cross-sectional view showing another aspect of the laminated adhesive sheet 10 of the present invention. As shown in FIG. 2, the laminated adhesive sheet 10 of the present invention includes a first adhesive layer 1, a second adhesive layer 2, and a resin layer 5. In the present invention, as shown in FIG. 2 (a), the resin layer 5 may be provided between the first adhesive layer 1 and the second adhesive layer 2. In this case, an adhesive layer is provided on both sides with the resin layer 5 as an intermediary, so the laminated adhesive sheet can function as a double-sided adhesive sheet.

Alternatively, as shown in FIG. 2 (b), the first adhesive layer 1 may be laminated on the resin layer 5, and the second resin layer 2 may be provided on the side opposite to the resin layer 5 through the first adhesive layer 1. In this case, since the second adhesive layer 2 is adhered to an adherend such as an optical member, the second adhesive layer 2 preferably contains a resin having excellent adhesiveness with the adherend.

The relative dielectric constant of the resin layer at 1 MHz is preferably 2 to 10. By setting the relative dielectric constant of the resin layer at 1 MHz to such a range, the relative dielectric constant of the laminated adhesive sheet can be easily adjusted, and the relative dielectric constant of the laminated adhesive sheet can be adjusted with good accuracy. The relative dielectric constant of the resin layer is preferably adjusted by appropriately selecting the type of resin to be used.

The thickness of the resin layer is preferably 10 to 500 μm, and more preferably 25 to 250 μm. If the thickness of the resin layer is greater than the above-mentioned lower limit value, it is easy to control the relative dielectric constant of the entire laminated adhesive sheet, and if the thickness of the resin layer is less than the above-mentioned upper limit value, the laminated adhesive can be easily manufactured. sheet.

(Laminated adhesive sheet with release sheet)

The laminated adhesive sheet of the present invention can be obtained, for example, by forming a coating film by applying the first adhesive composition and the second adhesive composition to a release sheet, and heating the coating film to obtain a cured product. Examples of the release sheet include a release laminate sheet having a substrate for a release sheet and a release agent layer provided on one side of the substrate for the release sheet, a polyethylene film as a low-polarity substrate, or Polyolefin film such as polypropylene film.

As a base material for a release sheet in a release laminated sheet, paper or a polymer film can be used. As the release agent constituting the release agent layer, for example, a general-purpose addition-type or condensation-type silicone release agent or a compound containing a long-chain alkyl group can be used.

Specific examples of the silicone release agent include BY24-4527 and SD-7220 manufactured by Dow Corning Toray Silicone, or KS-3600, KS-774, and X62- manufactured by Shin-Etsu Chemical Industry Co., Ltd. 2600 and so on. In addition, it is preferable that the polysilicone-based release agent contains polysilicon containing an organic silicon compound having SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units or CH ₂ = CH (CH ₃ ) SiO _1/2 units. Oxygen resin. Specific examples of the silicone resin include BY24-843, SD-7292, and SHR-1404 manufactured by Dow Corning Toray Silicone, or KS-3800 and X92-183 manufactured by Shin-Etsu Chemical Industry Co., Ltd.

In order to easily peel the release sheet, it is preferable that the first adhesive layer-side release sheet and the second adhesive layer-side release sheet have different releasability from each other. That is, if the releasability from one is different from the releasability from the other, it is easy to first peel only the release sheet with the higher releasability. In this case, it is only necessary to adjust the releasability of the first adhesive layer-side release sheet and the second adhesive layer-side release sheet according to the bonding method or the bonding order.

The application of the adhesive composition which forms each adhesive layer can be performed using a well-known application device. The adhesive composition can be applied to each adhesive layer, or the adhesive composition can be applied in multiple layers at the same time, thereby forming two or more adhesive layers. Examples of the coating device include a blade coater, an air knife coater, a roll coater, a bar coater, and a gravure plate. Coater, micro gravure coater, bar blade coater, die lip coater, die coater, curtain coater, etc. A solvent is contained in the coating liquid. As the solvent, for example, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, toluene, n-hexane, n-butanol, methyl isobutyl ketone, methyl butyl ketone, ethyl butyl ketone, Cyclohexanone, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, N-methyl-2-pyrrolidone, and the like. These can be used individually by 1 type or in mixture of 2 or more types.

The coating film can be heated using a known heating device such as a heating furnace or an infrared lamp.

The resin layer can also be formed using the coating device. When the resin layer is a non-adhesive resin layer, the resin layer can be molded by a known method, and is not particularly limited, and a biaxial stretching method, a melt extrusion method, or the like is preferred.

(Laminated body)

In the present invention, a laminated body can be produced by bonding a laminated adhesive sheet to at least one optical member. In the case where the laminated adhesive sheet is a double-sided adhesive sheet, a pair of optical members may be laminated on both sides of the laminated adhesive sheet.

The optical member constituting the laminated body refers to each constituent member in an optical product such as a touch panel or an image display device. Examples of the constituent members of the touch panel include: an ITO film provided with an ITO film on a transparent resin film, an ITO glass provided with an ITO film on a surface of a glass plate, and a transparent resin film coated with a conductive polymer. Conductive film, hard coat film, fingerprint-resistant film, etc. Examples of constituent members of the image display device include an antireflection film, an alignment film, a polarizing film, a retardation film, and a brightness enhancement film used in a liquid crystal display device. Examples of materials used for these members include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, and triethylpyrene. Cellulose, polyimide, tritiated cellulose, etc.

In addition, as a pair of optical members bonded by the laminated adhesive sheet of the present invention, Examples: the bonding of ITO films inside the touch panel, the bonding of ITO film and ITO glass, the bonding of ITO film of touch panel and liquid crystal panel, the bonding of cover glass and ITO film, cover glass and decoration Lamination of films, etc.

[Example]

Hereinafter, examples and comparative examples will be given to further specifically describe the features of the present invention. The materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed as long as they do not depart from the gist of the present invention. Therefore, the scope of the present invention should not be limitedly interpreted by the specific examples shown below.

(Preparation of the adhesive composition (A) contained in the first adhesive layer)

80 parts by mass of 2-ethylhexyl acrylate as a non-crosslinkable acrylate unit, 17 parts by mass of an ester and 3 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group were polymerized by a known solvent polymerization method to obtain an acrylate copolymer solution. An adhesive composition (A) was prepared by using the acrylate copolymer solution as an adhesive main agent.

As a release sheet, a release film having a release agent layer on a PET (polyethylene terephthalate) film [manufactured by Oji F-TECH Co., Ltd., 38 μm RL-07 (L)] was prepared and applied with a doctor blade. A cloth machine applies the solution of the above-mentioned adhesive composition (A) to the release agent layer of the release sheet, and heats it at 100 ° C for 3 minutes to form an adhesive layer with a thickness of 100 μm. The dielectric constant measurement system (Dongyang Technology 1260 type manufactured), and the relative dielectric constant was measured and detected based on JIS-C-2138. As a result, the relative dielectric constant ε ₁ at a frequency of 1 MHz was 2.6.

(Production of the adhesive composition (B) contained in the second adhesive layer)

40 parts by mass of methyl acrylate as a non-crosslinkable acrylate unit, 40 parts by mass of butyl acrylate, and 20 parts by mass of 2-hydroxyethyl acrylate as an acrylic monomer unit having a crosslinkable functional group are known. Polymerization was performed by a solvent polymerization method to obtain an acrylate copolymer solution. Adhesion using the acrylate copolymer solution as an adhesion main agent The adhesive solution is made into an adhesive composition (B).

As a release sheet, a release film having a release agent layer for PET film [manufactured by Oji F-TECH Co., Ltd., 38 μm RL-07 (L)] was prepared, and the release agent layer of the release sheet was applied by a doctor blade coater. The solution of the above-mentioned adhesive composition (B) was heated at 100 ° C. for 3 minutes to form an adhesive layer having a thickness of 100 μm, and the relative dielectric constant was measured. As a result, the relative dielectric constant ε ₂ at a frequency of 1 MHz was 5.4.

(Preparation of the adhesive composition (C) contained in the first adhesive layer)

80 parts by mass of 2-ethylhexyl acrylate, isopropyl acrylate 17 mass parts of esters and 3 mass parts of 4-hydroxybutyl acrylate were polymerized by a known block polymerization method to obtain an acrylate copolymer. 30 parts by mass of 2-ethylhexyl acrylate as a reactive diluent, 20 parts by mass of isooctyl acrylate, and 0.5 parts by mass of a photopolymerization initiator are added to 100 parts by mass of the acrylate copolymer. The adhesive slurry was prepared into an adhesive composition (C).

As a release sheet, a release film having a release agent layer on a PET film [manufactured by Ojito F-TECH Co., Ltd., 38 μm RL-07 (L)] was prepared, and the release agent layer of the release sheet was coated with a doctor blade The slurry containing the above-mentioned adhesive composition (C) was irradiated with a UV (ultraviolet, ultraviolet) irradiator while cooling under a nitrogen environment to irradiate a cumulative light amount of 1000 mJ / cm ² to form an adhesive layer having a thickness of 100 μm. The relative dielectric constant of this adhesive layer was measured and detected based on JIS-C-2138 by a dielectric constant measurement system (type 1260 manufactured by Toyo Technology). As a result, the relative dielectric constant ε ₁ at a frequency of 1 MHz was 2.4. .

(Production of the adhesive composition (D) contained in the second adhesive layer)

40 parts by mass of methyl acrylate as a non-crosslinkable acrylate unit, 40 parts by mass of butyl acrylate, and 20 parts by mass of 2-hydroxyethyl acrylate as an acrylic monomer unit having a crosslinkable functional group are known. Polymerization was carried out by a block polymerization method to obtain an acrylate copolymer. An adhesive slurry prepared by adding 50 parts by mass of lauryl acrylate and 0.5 parts by mass of a photopolymerization initiator to 100 parts by mass of the acrylate copolymer. Into an adhesive composition (D).

As a release sheet, a release film having a release agent layer for PET film [manufactured by Oji F-TECH Co., Ltd., 38 μm RL-07 (L)] was prepared, and the release agent layer of the release sheet was applied by a doctor blade coater. The slurry of the above-mentioned adhesive composition (D) was irradiated with a cumulative light amount of 1000 mJ / cm ² while being cooled by a UV irradiator under a nitrogen atmosphere to form an adhesive layer having a thickness of 100 μm. The relative dielectric constant of this adhesive layer was measured and detected based on JIS-C-2138 by a dielectric constant measurement system (type 1260 manufactured by Toyo Technology). As a result, the relative dielectric constant ε ₁ at a frequency of 1 MHz was 5.8. .

(Example 1) Production of laminated adhesive sheet

In order to use the adhesive composition (A) and (B) to produce a laminated adhesive sheet having a relative dielectric constant of 3.5, the ratio of the thickness of the first adhesive layer to the second adhesive layer was calculated using formula (1). The calculated thickness ratio is "(thickness of the first adhesive layer): (thickness of the second adhesive layer) = 1: 1", so the first adhesive layer and the second adhesive are formed in the following manner.剂 层。 The agent layer.

As a first release sheet, a release film having a release agent layer on a PET film [manufactured by Oji F-Tech Co., Ltd., 38 μm RL-07 (L)] was prepared, and the first release sheet was peeled off with a doctor blade coater The adhesive layer was coated with the solution of the adhesive composition (A), and heated at 100 ° C. for 3 minutes to form a first adhesive layer having a thickness of 50 μm.

As the second release sheet, a release film having a release agent layer on a PET film [manufactured by Oji F-TECH Co., Ltd., 38 μm RL-07 (L)] was prepared, and the second release sheet was peeled off with a doctor blade coater. The adhesive layer was coated with the solution of the adhesive composition (B), and heated at 100 ° C. for 3 minutes to form a second adhesive layer having a thickness of 50 μm.

The first adhesive layer and the second adhesive layer are brought into contact with each other so as to be overlapped and crimped. In this manner, a laminated adhesive sheet with a release sheet having a thickness of 100 μm of the adhesive layer was obtained.

(Example 2)

In order to use the adhesive composition (A) and (B), a product having a relative dielectric constant of 4.3 was prepared. For the layer adhesive sheet, the ratio of the thickness of the first adhesive layer to the thickness of the second adhesive layer was calculated using formula (1). The calculated thickness ratio is “(thickness of the first adhesive layer): (thickness of the second adhesive layer) = 1: 3”, so the thickness of the first adhesive layer is set to 25 μm, and the second adhesive layer is Except that the thickness of the adhesive layer was set to 75 μm, in the same manner as in Example 1, a laminated adhesive sheet with a release sheet having a thickness of 100 μm was obtained.

(Example 3)

In order to produce a laminated adhesive sheet having a relative dielectric constant of 3.0 using the adhesive compositions (A) and (B), the ratio of the thickness of the first adhesive layer to the thickness of the second adhesive layer was calculated using formula (1). The calculated thickness ratio is “(thickness of the first adhesive layer): (thickness of the second adhesive layer) = 3: 1”, so the thickness of the first adhesive layer is set to 75 μm, and the second adhesive layer is Except that the thickness of the adhesive layer was set to 25 μm, in the same manner as in Example 1, a laminated adhesive sheet with a release sheet with a thickness of 100 μm was obtained.

(Example 4) Production of a laminated adhesive sheet using a UV-curable adhesive composition

In order to use the adhesive compositions (C) and (D) to produce a laminated adhesive sheet having a relative dielectric constant of 3.5, the ratio of the thickness of the first adhesive layer to the second adhesive layer was calculated using the formula (1). The calculated thickness ratio is "(thickness of the first adhesive layer): (thickness of the second adhesive layer) = 0.9: 1.1", so the first adhesive layer and the second adhesive are formed in the following manner.剂 层。 The agent layer.

As a first release sheet, a release film having a release agent layer on a PET film [manufactured by Oji F-Tech Co., Ltd., 38 μm RL-07 (L)] was prepared, and the first release sheet was peeled off with a doctor blade coater. The agent layer was coated with the slurry of the above-mentioned adhesive composition (C), and was irradiated with a cumulative light amount of 1,000 mJ / cm ² while being cooled by a UV irradiator under a nitrogen atmosphere to form an adhesive layer having a thickness of 45 μm.

As the second release sheet, a release film having a release agent layer on a PET film [manufactured by Oji F-TECH Co., Ltd., 38 μm RL-07 (L)] was prepared, and the second release sheet was peeled off with a doctor blade coater. The agent layer was coated with the solution of the above-mentioned adhesive composition (D), and was irradiated with a cumulative light amount of 1000 mJ / cm ² while being cooled by a UV irradiator under a nitrogen atmosphere to form an adhesive layer having a thickness of 55 μm.

The first adhesive layer and the second adhesive layer are brought into contact with each other so as to be overlapped and crimped. In this manner, a laminated adhesive sheet with a release sheet having a thickness of 100 μm of the adhesive layer was obtained.

(Example 5)

In order to produce a laminated adhesive sheet having a relative dielectric constant of 4.4 using the adhesive compositions (C) and (D), the ratio of the thickness of the first adhesive layer to the thickness of the second adhesive layer was calculated using formula (1). The calculated thickness ratio is “(thickness of the first adhesive layer): (thickness of the second adhesive layer) = 1: 4”, so the thickness of the first adhesive layer is set to 20 μm, and the second adhesive layer is Except that the thickness of the adhesive layer was set to 80 μm, in the same manner as in Example 4, a laminated adhesive sheet with a release sheet with a thickness of 100 μm was obtained.

(Example 6)

In order to use the adhesive composition (C) and (D) to produce a laminated adhesive sheet having a relative dielectric constant of 3.0, the ratio of the thickness of the first adhesive layer to the thickness of the second adhesive layer was calculated using the formula (1). The calculated thickness ratio is “(thickness of the first adhesive layer): (thickness of the second adhesive layer) = 6.5: 3.5”, so the thickness of the first adhesive layer is set to 65 μm, and the second adhesive layer is Except that the thickness of the adhesive layer was set to 35 μm, in the same manner as in Example 4, a laminated adhesive sheet with a release sheet having a thickness of 100 μm was obtained.

(Measurement of Relative Dielectric Constant)

The relative dielectric constant of the laminated adhesive sheet obtained in the examples at a frequency of 1 MHz was measured, and the results are shown in Table 1. The theoretical relative permittivity refers to a value obtained by the formula (1).

[Number 3]

In the formula (1), ε represents the relative dielectric constant of the entire laminated adhesive sheet, and d represents the thickness of the entire laminated adhesive sheet. In addition, ε _n represents the relative dielectric constant of each adhesive layer, and d _n represents the thickness of each adhesive layer. In addition, n represents the number of layers of the adhesive layer.

From the results in Table 1, it can be seen that the relative permittivity obtained according to formula (1) is basically consistent with the measured relative permittivity. By using the calculation formula (1) in this manner, a laminated adhesive sheet having a desired relative dielectric constant can be easily manufactured.

Furthermore, a laminated adhesive sheet having a third adhesive layer was produced.

(Preparation of Adhesive Composition (1))

40 parts by mass of methyl acrylate as a non-crosslinkable acrylate unit, 40 parts by mass of butyl acrylate, and 20 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group are known. Polymerization was performed by a solvent polymerization method to obtain an acrylate copolymer solution. An adhesive solution (1) was prepared by using the acrylate copolymer solution as an adhesive main agent.

(Production of Adhesive Composition (2))

60 parts by mass of 2-ethylhexyl acrylate as a non-crosslinkable acrylate unit, 38 parts by mass of an ester and 2 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group were polymerized by a known solvent polymerization method to obtain an acrylate copolymer solution. An adhesive composition (2) was prepared by using the acrylate copolymer solution as an adhesive main agent.

(Preparation of Adhesive Composition (3))

30 parts by mass of methyl acrylate as a non-crosslinkable acrylate unit, 60 parts by mass of butyl acrylate, and 10 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group are known. Polymerization was performed by a solvent polymerization method to obtain an acrylate copolymer solution. An adhesive composition (3) was prepared by using the acrylate copolymer solution as an adhesive main agent.

(Example 7) Production of laminated adhesive sheet 7 with three adhesive layers

(1) Fabrication of the second adhesive layer

As a first release sheet, a release film having a release agent layer on a PET film [manufactured by Oji F-Tech Co., Ltd., 38 μm RL-07 (L)] was prepared, and the first release sheet was peeled off with a doctor blade coater. The adhesive layer was coated with the solution of the adhesive (2), and heated at 100 ° C. for 3 minutes to form a second adhesive layer. The relative dielectric constant ε _r of the formed second adhesive layer at a frequency of 100 Hz was 4.5.

In addition, in order to set the relative dielectric constant of the entire laminated adhesive sheet 7 to 5.5, the formula ( 1) The optimal thickness of the second adhesive layer was obtained. As a result, the second adhesive (2) was applied so that the thickness became 51 μm.

(2) Production of the first adhesive layer

As a second release sheet, a PET film having a release agent layer having a release property lower than that of the first release sheet described above [manufactured by Oji F-TECH Co., Ltd., 38 μm RL-07 (2)] was prepared, and applied with a doctor blade. The cloth was coated on the release agent layer of the second release sheet with a thickness of 25 μm, and the solution of the above-mentioned adhesive (1) was applied, and heated at 100 ° C. for 3 minutes to form a first adhesive layer. The relative dielectric constant ε _r of the first adhesive layer formed at a frequency of 100 Hz was 7.1.

(3) Production of the third adhesive layer

As the third release sheet, a release film similar to the first release film [38 μm RL-07 (L) manufactured by Oji F-TECH Co., Ltd.] was prepared, and a release agent was applied to the third release sheet using a blade coater. The layer was coated with the solution of the above-mentioned adhesive (1) so that the thickness became 25 μm, and heated at 100 ° C. for 3 minutes to form a third adhesive layer. The relative dielectric constant ε _r of the formed third adhesive layer at a frequency of 100 Hz was 7.1.

(4) Production of laminated adhesive sheet

After the second adhesive layer and the first adhesive layer are brought into contact with each other and overlapped and crimped, the first release sheet is peeled off to expose the second adhesive layer, so that the second adhesive layer and the third adhesive layer are adhered. After the agent layers are contacted and overlapped and crimped, a laminated adhesive sheet 7 with a release sheet is obtained. The thickness and relative dielectric constant of each layer of the laminated adhesive sheet 7 are shown in Table 2.

(Measurement of Relative Dielectric Constant of Laminated Adhesive Sheet)

The relative dielectric constant at a frequency of 100 k Hz of the laminated adhesive sheet 7 was measured. As a result, the relative dielectric constant ε _r of the obtained laminated adhesive sheet 7 at a frequency of 100 Hz was 5.4. In Table 3, the estimated and measured values of the relative dielectric constant at a frequency of 100 Hz of the laminated adhesive sheet 7 are shown.

As shown in Table 3, an adhesive layer with a lower relative dielectric constant is formed on the second adhesive layer, and its thickness is adjusted, thereby obtaining an actual measurement that the relative dielectric constant of the entire laminated adhesive sheet 7 is almost close to the estimated value. value. That is, it is considered that a laminated adhesive sheet having a desired relative dielectric constant is obtained.

(Example 8) Production of laminated adhesive sheet 8

An adhesive (1) was used for the first adhesive layer, an adhesive (2) was used for the second adhesive layer, and an adhesive (3) was used for the third adhesive layer. The laminated adhesive was produced in the same manner as in Example 7. Tablet 8. Furthermore, in order to set the relative permittivity of the laminated adhesive sheet 8 to 5.0, based on the thickness and relative permittivity of the first adhesive layer and the thickness and relative permittivity of the third adhesive layer, the formula ( 1) The optimal thickness of the second adhesive layer was obtained. As a result, the adhesive (2) was applied so that the thickness became 100 μm.

(Example 9) Production of laminated adhesive sheet 9

Except that the adhesive (3) was used for the first adhesive layer, the adhesive (1) was used for the second adhesive layer, and the adhesive (2) was used for the third adhesive layer, except that it was the same as in Example 8. Way to make laminated adhesive sheet 9.

Furthermore, in order to set the relative dielectric constant ε _{r of the} entire laminated adhesive sheet 9 to 6.3, based on the thickness and relative dielectric constant of the first adhesive layer, and the thickness and relative dielectric constant of the third adhesive layer, The optimum thickness of the second adhesive layer was obtained using the formula (1). As a result, the adhesive (1) was applied so that the thickness became 100 μm.

The thickness and relative dielectric constant of each layer of the laminated adhesive sheets 8 and 9 are shown in Table 4.

(Measurement of Relative Dielectric Constant of Laminated Adhesive Sheet)

The relative dielectric constants of the laminated adhesive sheets 8 and 9 at a frequency of 100 k Hz were measured, and the results are shown in Table 5.

As shown in Table 5, even when the relative dielectric constants of all the adhesive layers are different, the relative relative dielectric constant and thickness of the adhesive layer can be freely adjusted by controlling the relative dielectric constant and thickness of the adhesive layer. Dielectric constant.

[Industrial availability]

According to the present invention, a method for more accurately controlling the relative permittivity in a laminated adhesive sheet can be provided. Therefore, in the present invention, a laminated adhesive sheet having a desired relative dielectric constant can be obtained. The lamination of the laminated adhesive sheet of the present invention to the optical components is useful, for example, for lamination of ITO films in a touch panel sensor, or for lamination of a touch panel module and a liquid crystal module.

Claims (21)

A laminated adhesive sheet, characterized in that it has at least a first adhesive layer and a second adhesive layer, and the relative dielectric constant of the first adhesive layer and the second adhesive layer at a frequency of 1 MHz The absolute value of the difference is 0.5 or more. The first adhesive layer contains a member selected from the group consisting of 2-ethylhexyl (meth) acrylate unit, n-octyl (meth) acrylate unit, isooctyl (meth) acrylate unit, N-nonyl (meth) acrylate unit, isononyl (meth) acrylate unit, n-decyl (meth) acrylate unit, isodecyl (meth) acrylate unit, n-undecyl (meth) acrylate Ester unit, n-dodecyl (meth) acrylate unit, stearyl (meth) acrylate unit, cyclohexyl (meth) acrylate unit, benzyl (meth) acrylate unit, and acrylic acid isocyanate The second adhesive layer contains at least one non-crosslinkable (meth) acrylic acid ester unit and an acrylic monomer unit having a crosslinkable functional group in a group composed of an ester unit. Methyl acrylate unit, ethyl (meth) acrylate unit, propyl (meth) acrylate unit, isopropyl (meth) acrylate unit, n-butyl (meth) acrylate unit, isobutyl (meth) acrylate At least one non-crosslinkable (meth) acrylate unit in the group consisting of an ester unit and a third butyl (meth) acrylate unit, and an acrylic monomer unit having a crosslinkable functional group. For example, the laminated adhesive sheet of claim 1, which has at least a first adhesive layer and a second adhesive layer, and has a first adhesive layer with a relative dielectric constant of 4 at a frequency of 1 MHz and a frequency of 1 MHz The second adhesive layer having a relative dielectric constant of 4 or more. For example, the laminated adhesive sheet of claim 1 or 2, wherein the relative dielectric constant of the above-mentioned first adhesive layer at a frequency of 1 MHz does not reach 3. For example, the laminated adhesive sheet of claim 1 or 2, wherein the thickness of each layer of the first adhesive layer and the second adhesive layer is 10 μm or more. For example, the laminated adhesive sheet of claim 1 or 2, wherein the ratio of the thickness of the first adhesive layer to the thickness of the second adhesive layer is 1:99 to 99: 1. For example, the laminated adhesive sheet according to claim 1 or 2, wherein the first adhesive layer and the second adhesive layer are acrylic adhesive layers. For example, the laminated adhesive sheet of claim 1 or 2, wherein the relative dielectric constant of the first adhesive layer at a frequency of 1 MHz does not reach 3, and the thickness of each of the first adhesive layer and the second adhesive layer is 10 μm. As described above, the ratio of the thickness of the first adhesive layer to the thickness of the second adhesive layer is 1:99 to 99: 1. For example, the laminated adhesive sheet of claim 1 or 2, wherein the relative permittivity of the first adhesive layer at a frequency of 1 MHz does not reach 3, and the first adhesive layer and the second adhesive layer are acrylic adhesive layers. . If the laminated adhesive sheet of claim 1 or 2 further has a third adhesive layer. The laminated adhesive sheet as claimed in claim 1 or 2, further comprising a resin layer. For example, the laminated adhesive sheet according to claim 10, wherein the resin layer is provided between the first adhesive layer and the second adhesive layer. The laminated adhesive sheet according to claim 10, wherein the first adhesive layer is laminated on the resin layer, and the second adhesive layer is laminated on the side opposite to the resin layer through the first adhesive layer. For example, the laminated adhesive sheet of claim 10, wherein the relative dielectric constant of the resin layer at a frequency of 1 MHz is 2-10. A laminated body formed by bonding the laminated adhesive sheet according to any one of claims 1 to 13 to at least one optical member. The laminated body according to claim 14, wherein at least one of the optical members is ITO glass or ITO film. A relative dielectric constant adjusting method, characterized in that it is a method for adjusting the relative dielectric constant of a laminated adhesive sheet having at least two adhesive layers, and the laminated adhesive sheet has a relative dielectric constant at a frequency of 1 MHz or less. The first adhesive layer of 4 and the second dielectric layer having a relative dielectric constant at a frequency of 1 MHz or more are 4; by adjusting the relative dielectric constant and thickness of the first adhesive layer at a frequency of 1 MHz, and the first 2 The relative dielectric constant and thickness of the adhesive layer at a frequency of 1 MHz, and the relative dielectric constant of the laminated adhesive sheet is adjusted. N-octyl (meth) acrylate unit, isooctyl (meth) acrylate unit, n-nonyl (meth) acrylate unit, isononyl (meth) acrylate unit, n-decyl (meth) acrylate unit, Isodecyl (meth) acrylate unit, n-undecyl (meth) acrylate unit, n-dodecyl (meth) acrylate unit, stearyl (meth) acrylate unit, (meth) Cyclohexyl acrylate unit, benzyl (meth) acrylate unit, and propylene different The second adhesive layer contains at least one non-crosslinkable (meth) acrylic acid ester unit and an acrylic monomer unit having a crosslinkable functional group in a group composed of an ester unit. Methyl acrylate unit, ethyl (meth) acrylate unit, propyl (meth) acrylate unit, isopropyl (meth) acrylate unit, n-butyl (meth) acrylate unit, isobutyl (meth) acrylate At least one non-crosslinkable (meth) acrylate unit in the group consisting of an ester unit and a third butyl (meth) acrylate unit, and an acrylic monomer unit having a crosslinkable functional group. For example, the relative dielectric constant adjustment method of claim 16, wherein the relative dielectric constant and thickness of the first adhesive layer at a frequency of 1 MHz, and the relative dielectric constant and thickness of the second adhesive layer at a frequency of 1 MHz are Use the following formula (1) to adjust, (In formula (1), ε represents the relative dielectric constant of the entire laminated adhesive sheet, d represents the thickness of the entire laminated adhesive sheet; and ε _n represents the relative dielectric constant of each adhesive layer, and d _n represents each adhesive layer Thickness; furthermore, n represents the number of layers of the adhesive layer). For example, the relative dielectric constant adjustment method of claim 17, wherein in the above formula (1), d ₁ to d _n are determined so as to become a specific ε under the condition that ε ₁ to ε _n are fixed. For example, the relative dielectric constant adjustment method of claim 17, wherein in the above formula (1), ε ₁ to ε _n-1 and d ₁ to d _{n-1 are} determined under the condition that ε _n and d _n are fixed. . For example, the relative dielectric constant adjustment method of claim 17, wherein n is 2 in the above formula (1). A method for manufacturing a laminated adhesive sheet, which is characterized in that it is a method for manufacturing a laminated adhesive sheet having at least two adhesive layers, and the relative dielectric constant adjustment method of claim 17 is used to adjust the relative dielectric constant of the laminated adhesive sheet. Dielectric constant.