WO2014181853A1 - Laminated adhesive sheet and laminate - Google Patents

Abstract

The purpose of the present invention is to find a method for controlling relative permittivity more accurately and to provide an adhesive sheet in which the relative permittivity is controlled by said controlling method. The present invention relates to a laminated adhesive sheet including at least a first adhesive agent layer and a second adhesive agent layer, wherein the absolute value of the difference in relative permittivity at a frequency of 1 MHz between the first adhesive agent layer and the second adhesive agent layer is 0.5 or greater. The present invention also relates to a laminated adhesive sheet comprising a first adhesive agent layer in which the relative permittivity at a frequency of 1 MHz is less than 4, and a second adhesive agent layer in which the relative permittivity at a frequency of 1 MHz is 4 or greater.

Description

Laminated adhesive sheet and laminate

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

In recent years, display devices such as a liquid crystal display (LCD) and input devices used in combination with a display device such as a touch panel have been widely used in various fields. In the production of these display devices and input devices, transparent double-sided pressure-sensitive adhesive sheets are used for bonding optical members, and transparent double-sided pressure-sensitive adhesive sheets are also used for bonding between display devices and input devices. (For example, Patent Documents 1 to 3).

In such display devices and input devices, the adhesive sheet is required to have various functions such as insulating properties as well as adhesive physical properties. For example, Patent Document 4 discloses a laminated pressure-sensitive adhesive sheet having different dielectric constants. Patent Document 5 discloses a single-layer type pressure-sensitive adhesive sheet having a specific dielectric constant and dielectric loss tangent. As described above, it has been proposed to improve the operation performance of the touch panel by controlling the dielectric constant of the adhesive sheet.

JP 2003-238915 A JP 2003-342542 A JP 2004-231723 A Japanese Patent No. 4093355 International Publication 2010/147047 Pamphlet

As described above, the dielectric constant of the pressure-sensitive adhesive sheet is required to be controlled within a predetermined range according to the performance required for the display device and the input device. However, since the relative dielectric constant is a physical property value specific to a substance, it is not always easy to control with high accuracy, and it has been desired to find a method for controlling the relative dielectric constant more accurately.

Therefore, the present inventors have found a method for controlling the relative permittivity more accurately in order to solve the problems of the conventional technology, and provide an adhesive sheet whose relative permittivity is controlled by the control method. We proceeded with a study for this purpose.

As a result of intensive studies to solve the above problems, the present inventors have determined that the ratio of the first pressure-sensitive adhesive layer in the laminated pressure-sensitive adhesive sheet having at least the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. It was found that the relative dielectric constant of the laminated adhesive sheet can be adjusted by adjusting the dielectric constant and thickness and the relative dielectric constant and thickness of the second pressure-sensitive adhesive layer to satisfy specific conditions. Thus, the present inventors succeeded in obtaining a laminated pressure-sensitive adhesive sheet having a controlled relative dielectric constant, and completed the present invention.
Specifically, the present invention has the following configuration.

（式（１）中、εは、積層粘着シート全体の比誘電率を表し、ｄは、積層粘着シート全体の厚みを表す。また、ε_nは、各粘着剤層の比誘電率を表し、ｄ_nは、各粘着剤層の厚みを表す。なお、ｎは、粘着剤層の層数を表す。）
［１７］前記式（１）において、ε₁～ε_nが固定されている条件下で、特定のεとなるように、ｄ₁～ｄ_nを決定することを特徴とする［１６］に記載の比誘電率調整方法。
［１８］前記式（１）において、ε_nとｄ_nが固定されている条件下で、特定のεとなるように、ε₁～ε_n-1と、ｄ₁～ｄ_n-1を決定することを特徴とする［１６］に記載の比誘電率調整方法。
［１９］前記式（１）において、ｎは２であることを特徴とする［１６］～［１８］のいずれかに記載の比誘電率調整方法。
［２０］少なくとも２層の粘着剤層を有する積層粘着シートの製造方法であって、［１６］～［１９］のいずれかに記載の比誘電率調整方法によって積層粘着シートの比誘電率を調節することを特徴とする積層粘着シートの製造方法。 [1] A laminated pressure-sensitive adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer, wherein a difference in relative dielectric constant between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at a frequency of 1 MHz A laminated pressure-sensitive adhesive sheet having an absolute value of 0.5 or more.
[2] A laminated pressure-sensitive adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer, a first pressure-sensitive adhesive layer having a relative dielectric constant at a frequency of 1 MHz of less than 4, and a relative dielectric constant at a frequency of 1 MHz Has 4 or more 2nd adhesive layers, The laminated adhesive sheet as described in [1] characterized by the above-mentioned.
[3] The laminated pressure-sensitive adhesive sheet according to [1] or [2], wherein the first pressure-sensitive adhesive layer has a relative dielectric constant of less than 3 at a frequency of 1 MHz.
[4] The laminated pressure-sensitive adhesive sheet according to any one of [1] to [3], wherein the thickness of each of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 10 μm or more.
[5] The ratio of the thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 1:99 to 99: 1, according to any one of [1] to [4] Laminated adhesive sheet.
[6] The laminated pressure-sensitive adhesive sheet according to any one of [1] to [5], wherein the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are acrylic pressure-sensitive adhesive layers.
[7] The laminated pressure-sensitive adhesive sheet according to any one of [1] to [6], wherein the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer contain (meth) acrylic acid ester.
[8] The laminated pressure-sensitive adhesive sheet according to any one of [1] to [7], further comprising a third pressure-sensitive adhesive layer.
[9] The laminated pressure-sensitive adhesive sheet according to any one of [1] to [8], further comprising a resin layer.
[10] The laminated pressure-sensitive adhesive sheet according to [9], wherein the resin layer is provided between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer.
[11] The first pressure-sensitive adhesive layer is laminated on the resin layer, and the second pressure-sensitive adhesive layer is laminated on the opposite side of the resin layer via the first pressure-sensitive adhesive layer. The laminated pressure-sensitive adhesive sheet according to [9], wherein
[12] The laminated adhesive sheet according to any one of [9] to [11], wherein the resin layer has a relative dielectric constant of 2 to 10 at a frequency of 1 MHz.
[13] A laminate comprising the laminated pressure-sensitive adhesive sheet according to any one of [1] to [12] attached to at least one optical member.
[14] The laminate according to [13], wherein at least one of the optical members is ITO glass or an ITO film.
[15] A method for adjusting the relative dielectric constant of a laminated pressure-sensitive adhesive sheet having at least two pressure-sensitive adhesive layers, the laminated pressure-sensitive adhesive sheet comprising: a first pressure-sensitive adhesive layer having a relative dielectric constant of less than 4 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, a relative dielectric constant and thickness of the first adhesive layer at a frequency of 1 MHz, and a relative dielectric constant of the second adhesive layer at a frequency of 1 MHz. A relative dielectric constant adjusting method, wherein the relative dielectric constant of the laminated adhesive sheet is adjusted by adjusting the rate and the thickness, respectively.
[16] The relative dielectric constant and thickness of the first pressure-sensitive adhesive layer at a frequency of 1 MHz and the relative dielectric constant and thickness of the second pressure-sensitive adhesive layer at a frequency of 1 MHz are adjusted using the following formula (1). The relative dielectric constant adjusting method according to [15], wherein

(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, d _n represents the thickness of each adhesive layer. Here, n represents the number of layers of the pressure-sensitive adhesive layer.)
[17] In the above equation (1), d ₁ to d _n are determined so as to be a specific ε under a condition where ε ₁ to ε _n are fixed. The relative dielectric constant adjustment method.
[18] In the formula (1), under conditions epsilon _n and d _n are fixed, determined to be specific epsilon, and epsilon ₁ ~ epsilon _n-1, the d ₁ ~ d _n-1 The method of adjusting the dielectric constant according to [16], wherein:
[19] The relative dielectric constant adjusting method according to any one of [16] to [18], wherein in the formula (1), n is 2.
[20] A method for producing a laminated pressure-sensitive adhesive sheet having at least two pressure-sensitive adhesive layers, wherein the relative dielectric constant of the laminated pressure-sensitive adhesive sheet is adjusted by the relative dielectric constant adjusting method according to any one of [16] to [19] A method for producing a laminated pressure-sensitive adhesive sheet, comprising:

According to the present invention, it is possible to provide a method for controlling the relative dielectric constant more accurately in the laminated adhesive sheet. For this reason, in this invention, the lamination adhesive sheet which has a desired dielectric constant can be obtained. Further, in the present invention, since the relative dielectric constant can be accurately controlled in the laminated adhesive sheet, the production efficiency of the laminated adhesive sheet can be increased, and the detailed needs required when producing a laminate are met. I can do things.

FIG. 1 is a schematic cross-sectional view of the laminated pressure-sensitive adhesive sheet of the present invention. FIG. 2 is a schematic cross-sectional view showing another aspect of the laminated pressure-sensitive adhesive sheet of the present invention.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

(Laminated adhesive sheet)
The present invention relates to a laminated pressure-sensitive adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer. In the laminated pressure-sensitive adhesive sheet of the present invention, the absolute value of the difference in relative dielectric constant at a frequency of 1 MHz between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 0.5 or more. Moreover, it is preferable that the dielectric constant in the frequency 1MHz of the 1st adhesive layer of the laminated adhesive sheet of this invention is less than 4, and the dielectric constant in the frequency 1MHz of the 2nd adhesive layer is 4 or more. The laminated pressure-sensitive adhesive sheet of the present invention can function as a double-sided pressure-sensitive adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer.

1 (a) to 1 (d) are schematic cross-sectional views of the laminated adhesive sheet 10 of the present invention. As shown in FIGS. 1A to 1C, the laminated pressure-sensitive adhesive sheet 10 has a first pressure-sensitive adhesive layer 1 and a second pressure-sensitive adhesive layer 2. 1 (a) to 1 (c), the laminated pressure-sensitive adhesive sheet 10 is composed of only the first pressure-sensitive adhesive layer 1 and the second pressure-sensitive adhesive layer 2, but has other functional layers and pressure-sensitive adhesive layers. It may be. For example, as shown in FIG. 1 (d), the laminated pressure-sensitive adhesive sheet 10 of the present invention includes a third pressure-sensitive adhesive layer 3 in addition to the first pressure-sensitive adhesive layer 1 and the second pressure-sensitive adhesive layer 2. You may have. When the laminated pressure-sensitive adhesive sheet 10 has a functional layer other than the pressure-sensitive adhesive layer, at least one of the first pressure-sensitive adhesive layer 1, the second pressure-sensitive adhesive layer 2, and the third pressure-sensitive adhesive layer 3 is the outermost layer. Placed in.

In the laminated pressure-sensitive adhesive sheet of the present invention, the absolute value of the difference in relative dielectric constant between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 0.5 or more. The absolute value of the difference in relative dielectric constant between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is preferably 1 or more, and more preferably 2 or more. By adjusting the relative dielectric constant difference between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer as described above, the adjustment of the relative dielectric constant of the laminated pressure-sensitive adhesive sheet is facilitated, and the ratio of the laminated pressure-sensitive adhesive sheet is more accurate. The dielectric constant can be adjusted.

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

The relative dielectric constant at a frequency of 1 MHz of the second pressure-sensitive adhesive layer is preferably 4 or more, more preferably 4.5 or more, further preferably 5 or more, and 5.5 or more. Is even more preferable. Thus, the relative dielectric constant of the first pressure-sensitive adhesive layer at a frequency of 1 MHz and the relative dielectric constant of the second pressure-sensitive adhesive layer at a frequency of 1 MHz are set to a specific range, thereby controlling the relative dielectric constant of the entire laminated adhesive sheet. can do.

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

The ratio of the thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is preferably 1:99 to 99: 1. Thus, by adjusting the thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, the relative dielectric constant of the entire laminated pressure-sensitive adhesive sheet can be controlled.

In the laminated pressure-sensitive adhesive sheet of the present invention, the relative dielectric constant of the whole laminated pressure-sensitive adhesive sheet can be controlled by providing the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer under specific conditions. Specifically, the relative permittivity of the laminated adhesive sheet can be controlled by adjusting the relative permittivity and thickness of the first adhesive layer and the relative permittivity and thickness of the second adhesive layer, respectively. it can.
In the present invention, the relative dielectric constant and thickness of the first pressure-sensitive adhesive layer and the relative dielectric constant and thickness of the second pressure-sensitive 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. Further, the epsilon _n, represents the dielectric constant of the adhesive layer, d _n represents the thickness of each adhesive layer. Note that n represents the number of pressure-sensitive adhesive layers.

In the present invention, when forming a laminated pressure-sensitive adhesive sheet having a specific dielectric constant, the dielectric constant and thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer using the above formula (1) The relative dielectric constant and thickness can be calculated. That is, if the relative dielectric constant required for the laminated adhesive sheet is determined and the thickness of the required laminated adhesive sheet is determined, the relative dielectric constant and thickness of the first adhesive layer and the second adhesive layer are calculated. be able to.

In the present invention, specifically, the dielectric constant is preferably adjusted under the following conditions. For example, in the above formula (1), d ₁ to d _n can be determined so as to be a specific ε under conditions where ε ₁ to ε _n are fixed. In the above formula (1), under conditions epsilon _n and d _n are fixed, and ε ₁ ~ ε _n-1, it is possible to determine the d ₁ ~ d _n-1.
Thus, by setting conditions according to the mode of the laminated pressure-sensitive adhesive sheet, a desired dielectric constant can be obtained while selecting a pressure-sensitive adhesive having an adhesive property according to the adherend using the above formula (1). A laminated pressure-sensitive adhesive sheet having the following can be formed.

In the present invention, in the above formula (1), n is preferably 2 to 6, more preferably 2 to 4, and still more preferably 2 or 3. By using said Formula (1), it becomes possible to adjust easily the dielectric constant of the laminated adhesive sheet which has two or more adhesive layers.

The laminated pressure-sensitive adhesive sheet of the present invention may have a third pressure-sensitive adhesive layer. When the laminated pressure-sensitive adhesive sheet has a third pressure-sensitive adhesive layer, the third pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer having the same dielectric constant as the first pressure-sensitive adhesive layer or the second pressure-sensitive adhesive layer that is not adjacent to each other. Alternatively, it may be a pressure-sensitive adhesive layer having the same dielectric constant as the adjacent first pressure-sensitive adhesive layer or second pressure-sensitive adhesive layer. That is, the third pressure-sensitive adhesive layer may have the same dielectric constant as that of the adjacent pressure-sensitive adhesive layer, or may have a different relative dielectric constant. Moreover, when the 1st adhesive layer, the 2nd adhesive layer, and the 3rd adhesive layer are laminated | stacked in this order, the dielectric constant of the 1st adhesive layer and the 3rd adhesive layer is It may be the same.

Further, the third pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer having a relative dielectric constant different from any of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. When the laminated pressure-sensitive adhesive sheet has a third pressure-sensitive adhesive layer, the absolute difference between the relative dielectric constant of the third pressure-sensitive adhesive layer and the relative dielectric constant of the adjacent first pressure-sensitive adhesive layer or second pressure-sensitive adhesive layer The value is preferably 0.5 or more, more preferably 1 or more, and even more preferably 2 or more. Furthermore, the absolute value of the difference in relative dielectric constant between all the adhesive layers is also preferably within the above range. That is, the absolute value of the difference between the relative dielectric constant of the first pressure-sensitive adhesive layer and the relative dielectric constant of the second pressure-sensitive adhesive layer is preferably within the above range, and the relative dielectric constant of the second pressure-sensitive adhesive layer The absolute value of the difference in relative dielectric constant of the pressure-sensitive adhesive layer 3 is preferably within the above range, and the absolute value of the difference in relative dielectric constant between the first pressure-sensitive adhesive layer and the third pressure-sensitive adhesive layer is within the above range. It is preferable that

If the laminated pressure-sensitive adhesive sheet having a three-layered or more pressure-sensitive adhesive layer, in the above formula (1), under conditions epsilon ₁ and epsilon _n, d ₁ and d _n are fixed, ε ₂ ~ ε _n-1 and , D ₂ to d _n-1 can also be determined. In this case, a laminated pressure-sensitive adhesive sheet having a desired relative dielectric constant can be formed by adjusting the relative dielectric constant and thickness of the pressure-sensitive adhesive layer present inside the laminated pressure-sensitive adhesive sheet.

That is, in the case of a laminated pressure-sensitive adhesive sheet having n of 3 or more, a pressure-sensitive adhesive having appropriate pressure-sensitive adhesive properties according to the adherend as an adhesive layer in contact with the adherend (hereinafter referred to as the outermost pressure-sensitive adhesive layer) and a thickness are set in advance. The thickness of layers other than the outermost pressure-sensitive adhesive layer for obtaining the desired dielectric constant of the entire laminated pressure-sensitive adhesive sheet can be obtained by using the above formula (1). it can. Thereby, the laminated adhesive sheet which can achieve a desired adhesive physical property and a dielectric constant simultaneously is obtained.

The thickness of each of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer of the laminated pressure-sensitive adhesive sheet of the present invention is preferably 10 μm or more. If it is more than the said lower limit, the relative dielectric constant of the whole lamination adhesive sheet can be adjusted with sufficient accuracy. The total thickness of the laminated pressure-sensitive adhesive sheet is preferably 20 to 1000 μm, particularly the thickness of the outermost pressure-sensitive adhesive layer is preferably 10 to 100 μm, and more preferably 25 to 50 μm. By adjusting the thickness of the outermost pressure-sensitive adhesive layer within the above range, a laminated pressure-sensitive adhesive sheet having pressure-sensitive adhesive properties corresponding to the adherend is obtained. Moreover, also when the laminated adhesive sheet of this invention has a 3rd adhesive layer, it is preferable that the thickness of a 3rd adhesive layer exists in the said range.

Thus, the present invention is a method for adjusting the relative dielectric constant of a laminated adhesive sheet having at least two pressure-sensitive adhesive layers, and also relates to a relative dielectric constant adjusting method using the above formula (1). By using the relative dielectric constant adjusting method of the present invention, laminated adhesive sheets having various relative dielectric constants can be easily formed. Thereby, the relative dielectric constant of the entire laminated adhesive sheet can be controlled with high accuracy.

Furthermore, the present invention is a method for producing a laminated pressure-sensitive adhesive sheet having at least two pressure-sensitive adhesive layers, and a step of adjusting the relative dielectric constant of the laminated pressure-sensitive adhesive sheet by the relative dielectric constant adjusting method using the above formula (1). It is also related with the manufacturing method of the lamination adhesive sheet containing this. By using such a manufacturing method, the production efficiency of a laminated adhesive sheet can also be improved.

(Adhesive)
As the adhesive main agent that forms the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, it is preferable to use a transparent material so as not to lower the visibility of a display device or the like. For example, known pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, and polyurethane-based pressure-sensitive adhesives can be used. Among these, an acrylic pressure-sensitive adhesive is preferably used, and an acrylic pressure-sensitive adhesive containing an acrylic polymer as a base polymer is preferable.

<Acrylic polymer>
The acrylic polymer contains a non-crosslinkable (meth) acrylic acid ester unit and an acrylic monomer unit having a crosslinkable functional group. Here, the “monomer unit” is a repeating unit constituting the polymer. An “acrylic monomer” is a compound having a (meth) acryloyl group. “(Meth) acryloyl group” means an acryloyl group or a methacryloyl group. The non-crosslinkable acrylic monomer is an acrylic monomer having no crosslinkable group, and the crosslinkable monomer is a monomer having a crosslinkable group. The crosslinkable monomer may be an acrylic monomer or a non-acrylic monomer as long as it is polymerizable with the non-crosslinkable acrylic monomer, and is preferably an acrylic monomer. . Examples of the crosslinkable group include a carboxy group, a hydroxy group, an amino 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 carboxy group of (meth) acrylic acid is substituted with a hydrocarbon group. In this invention, it is preferable that each adhesive layer contains a (meth) acrylic acid ester unit.

The number of carbon atoms of the hydrocarbon group in the (meth) acrylate unit is preferably 1-18, and more preferably 1-8. The hydrocarbon group may have a substituent, and 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 (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, ( Isobutyl acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate , Isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isobornyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, (meth) N-undecyl acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, (meth ) Methoxyethyl acrylate, ethoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate include benzyl (meth) acrylate. Of these, n-butyl acrylate, 2-ethylhexyl acrylate, and methyl acrylate are preferably used from the viewpoint of adhesiveness. These may be used individually by 1 type and may use 2 or more types together. In the present invention, “(meth) acrylic acid” means containing both “acrylic acid” and “methacrylic acid”.

As the crosslinkable monomer unit, a carboxy group-containing copolymerizable monomer unit, a hydroxy group-containing copolymerizable monomer unit, an amino group-containing copolymerizable monomer unit, a glycidyl group-containing copolymerizable monomer Examples include body units. Examples of the carboxy group-containing copolymerizable monomer include α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and grataconic acid, and anhydrides thereof. Such as things.
Examples of the hydroxy group-containing copolymerizable monomer include (meth) acrylic acid such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxypropyl (meth) acrylate. (Meth) acrylic acid lactones such as hydroxyalkyl, (meth) acrylic acid (meth) acrylic acid mono (diethylene glycol) [(mono, di or poly) alkylene glycol], (meth) acrylic acid monocaprolactone and the like.
Examples of the amino group-containing copolymerizable monomer include (meth) acrylamide and allylamide.
Examples of the glycidyl group-containing copolymerizable monomer include glycidyl (meth) acrylate.
Among these, from the point of low adhesiveness, crosslinkability and polymerizability, and the corrosiveness of metals such as tin-doped indium oxide used for transparent conductive films and copper used for electromagnetic shielding, a hydroxy group-containing copolymerizable monomer Is preferred, hydroxyalkyl (meth) acrylate is more preferred, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate is particularly preferred.

In addition, when a carboxy group-containing copolymerizable monomer unit is contained as a crosslinkable monomer unit, the acidity becomes strong, so when a corrosive film such as a tin-doped indium oxide film or a metal film is in contact with these, May corrode the film. For this reason, from the point of corrosion prevention, when containing a carboxy group-containing copolymerizable monomer unit as a crosslinkable monomer unit, the content is preferably less than 0.5% by mass, More preferably it is not contained at all. Moreover, it is preferable that the content rate of the carboxy group containing copolymerizable monomer unit in this acrylic polymer is less than 1.0 mass% from the point of corrosion prevention as the whole lamination adhesive sheet.

The acrylic polymer may have other monomer units other than the non-crosslinkable acrylic monomer unit and the crosslinkable monomer unit. Examples of other monomers include (meth) acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinyl pyrrolidone, vinyl pyridine and the like.
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 of other monomer units is not less than the above lower limit, the physical properties can be easily adjusted, and if it is not more than the above upper limit, yellowing due to deterioration with time can be prevented.

The relative dielectric constant of each pressure-sensitive adhesive layer can be set to a desired value by appropriately selecting the type of resin used for the pressure-sensitive adhesive. For example, in order to increase the dielectric constant, (meth) acrylic acid ester units having a relatively high polarity, such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic It is preferable to use isopropyl acid, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, or the like. Of these, methyl (meth) acrylate and n-butyl (meth) acrylate are preferred from the viewpoints of transparency and adhesion between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer.
In addition, as the crosslinkable monomer unit, similarly, a relatively high carboxyl group-containing copolymerizable monomer unit, hydroxy group-containing copolymerizable monomer unit, amino group-containing copolymerizable monomer unit As the carboxy group-containing copolymerizable monomer, for example, α, β-unsaturation such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, grataconic acid, etc. Examples of the carboxylic acid, anhydride thereof, and hydroxy group-containing copolymerizable monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxypropyl (meth) acrylate. (Meth) acrylic acid ((mono, di or poly) a) such as (meth) acrylic acid hydroxyalkyl, (meth) acrylic acid mono (diethylene glycol) Examples of (meth) acrylic acid lactone and amino group-containing copolymerizable monomers such as (alkylene glycol] and (meth) acrylic acid monocaprolactone include (meth) acrylamide and allylamide. Among these, from the viewpoint of easy control of the relative dielectric constant, the proportion of polar groups in the whole molecule is high, so 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferred.

On the other hand, when the relative dielectric constant of the pressure-sensitive adhesive layer is lowered, a material having a low polarity may be used. For example, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate , Isodecyl (meth) acrylate, n-undecyl (meth) acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl acrylate And cycloaliphatic compounds such as isobornyl acrylate. Among them, (meth) acrylic acid 2- (meth) acrylic acid 2- Ethylhexyl and isobornyl (meth) acrylate are preferred.

<Crosslinking agent>
A crosslinking agent may be used for each pressure-sensitive adhesive layer. Examples of the crosslinking agent include isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, metal chelate compounds, butylated melamine compounds, and the like. Among these crosslinking agents, an isocyanate compound and an epoxy compound are preferable because the acrylic polymer can be easily crosslinked. In particular, when the acrylic polymer contains only a hydroxy group-containing copolymerizable monomer unit as a crosslinkable monomer unit, it is preferable to use an isocyanate compound because of the reactivity of the hydroxy group.
Examples of the isocyanate compound include tolylene 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, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol diester. Glycidyl ether, tetraglycidyl xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, etc. Can be mentioned. It is preferable that the content of the crosslinking agent is appropriately selected according to the desired pressure-sensitive adhesive properties.

[Additive]
In addition, each pressure-sensitive adhesive layer may include an antioxidant, a metal corrosion inhibitor, a tackifier, a silane coupling agent, an ultraviolet absorber, a light stabilizer such as a hindered amine compound, a filler, and the like as necessary. May be included.
Examples of the antioxidant include phenolic antioxidants, amine-based antioxidants, lactone-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like. These antioxidants may be used alone or in combination of two or more.
As the metal corrosion inhibitor, a benzotriazole-based resin is preferable because of the compatibility and high effect of the pressure-sensitive adhesive.
Examples of the tackifier include rosin resins, terpene resins, terpene phenol resins, coumarone indene resins, styrene resins, xylene resins, phenol resins, petroleum resins, and the like.
Examples of the silane coupling agent include mercaptoalkoxysilane compounds (for example, mercapto group-substituted alkoxy oligomers).
Examples of the ultraviolet absorber include benzotriazole compounds and benzophenone compounds.

(Resin layer)
The laminated pressure-sensitive adhesive sheet of the present invention may further have a resin layer in addition to the above-described first pressure-sensitive adhesive layer, second pressure-sensitive adhesive layer, and third pressure-sensitive adhesive layer. The resin layer may be an adhesive layer or a non-adhesive resin layer. Further, it may be a single layer or a plurality of layers. When the resin layer is a non-adhesive resin layer, the resin used is preferably one that does not affect the optical properties, such as polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose. , Polyimide, cellulose acylate and the like.
In the case where the resin layer is a pressure-sensitive adhesive layer, the pressure-sensitive adhesive agent having a transparency that does not deteriorate the visibility of the display device is preferable, as in the case of the pressure-sensitive adhesive agent used in each pressure-sensitive adhesive layer. For example, known adhesives such as acrylic adhesives, silicone adhesives, polyester adhesives, rubber adhesives, polyurethane adhesives and the like can be used. An acrylic pressure-sensitive adhesive containing, as a base polymer, an acrylic polymer containing (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms as a main monomer component is preferable.

In FIG. 2, the schematic sectional drawing showing the other aspect of the lamination adhesive sheet 10 of this invention is shown. As shown in FIG. 2, the laminated pressure-sensitive adhesive sheet 10 of the present invention has a first pressure-sensitive adhesive layer 1, a second pressure-sensitive adhesive layer 2, and a resin layer 5. In the present invention, the resin layer 5 may be provided between the first pressure-sensitive adhesive layer 1 and the second pressure-sensitive adhesive layer 2 as shown in FIG. In this case, since the pressure-sensitive adhesive layer is provided on both surfaces via the resin layer 5, the laminated pressure-sensitive adhesive sheet can function as a double-sided pressure-sensitive adhesive sheet.
Further, as shown in FIG. 2B, the first pressure-sensitive adhesive layer 1 is laminated on the resin layer 5, and the second resin layer is disposed on the opposite side of the resin layer 5 through the first pressure-sensitive adhesive layer 1. 2 may be provided. In this case, since the second pressure-sensitive adhesive layer 2 adheres to an adherend such as an optical member, the second pressure-sensitive adhesive layer 2 preferably contains a resin excellent in adhesiveness to the adherend.

The relative dielectric constant of the resin layer at a frequency of 1 MHz is preferably 2 to 10. By setting the relative dielectric constant of the resin layer at a frequency of 1 MHz in 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 more accurately. The relative dielectric constant of the resin layer is preferably adjusted by appropriately selecting the type of resin used.

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

(Laminated adhesive sheet with release sheet)
The laminated pressure-sensitive adhesive sheet of the present invention is formed, for example, by coating the first pressure-sensitive adhesive composition and the second pressure-sensitive adhesive composition on a release sheet to form a coating film, and heating the coating film to obtain a cured product. Can be obtained. As a release sheet, a peelable laminate sheet having a release sheet substrate and a release agent layer provided on one side of the release sheet substrate, or a polyolefin film such as a polyethylene film or a polypropylene film as a low polarity substrate Is mentioned.

Papers and polymer films are used as the release sheet substrate in the peelable laminate sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition type or condensation type silicone release agent or a long-chain alkyl group-containing compound is used.
Specific examples of silicone release agents include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicone, KS-3600, KS-774, and X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. Is mentioned. Further, the silicone release agent may contain a silicone resin which is an organosilicon compound having a SiO ₂ unit and a (CH ₃ ) ₃ SiO _1/2 unit or CH ₂ ═CH (CH ₃ ) SiO _1/2 unit. preferable. Specific examples of the silicone resin include BY24-843, SD-7292, SHR-1404 manufactured by Toray Dow Corning Silicone, KS-3800, X92-183 manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

In order for the release sheet to be easily peeled off, it is preferable that the first adhesive layer side release sheet and the second adhesive layer side release sheet have different peelability. That is, when the peelability from one side and the peelability from the other are different, it becomes easy to peel only the release sheet having the higher peelability first. In that case, what is necessary is just to adjust the peelability of a 1st adhesive layer side peeling sheet and a 2nd adhesive layer side peeling sheet according to the bonding method and the bonding order.

The application of the pressure-sensitive adhesive composition for forming each pressure-sensitive adhesive layer can be carried out using a known coating apparatus. The pressure-sensitive adhesive composition may be applied to each pressure-sensitive adhesive layer, or two or more pressure-sensitive adhesive layers may be formed by simultaneous multilayer coating of the pressure-sensitive adhesive composition. Examples of the coating apparatus include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, and a curtain coater. The coating liquid contains a solvent. Examples of the solvent include methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, toluene, n-hexane, n-butyl alcohol, 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 are used. These may be used alone or in combination of two or more.
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 above coating apparatus. In addition, when the resin layer is a non-adhesive resin layer, it can be molded by a known method and is not particularly limited, but a biaxial stretching method, a melt extrusion method, or the like is preferable.

(Laminate)
In this invention, a laminated body can be produced by sticking a laminated adhesive sheet to at least one optical member. When the laminated adhesive sheet is a double-sided adhesive sheet, a pair of optical members can be bonded to both sides of the laminated adhesive sheet.

The optical member constituting the laminate is each constituent member in an optical product such as a touch panel or an image display device. As a constituent member of the touch panel, for example, an ITO film in which an ITO film is provided on a transparent resin film, an ITO glass in which an ITO film is provided on the surface of a glass plate, a transparent conductive film in which a transparent polymer film is coated with a conductive polymer, Examples thereof include a hard coat film and an anti-fingerprint film. Examples of the constituent member 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, triacetyl cellulose, polyimide, and cellulose acylate.
Moreover, as a pair of optical members bonded by the laminated pressure-sensitive adhesive sheet of the present invention, bonding between ITO films inside the touch panel, bonding between ITO film and ITO glass, touch panel ITO film and liquid crystal panel Examples include bonding, bonding between a cover glass and an ITO film, and bonding between a cover glass and a decorative film.

Hereinafter, the features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

(Production of pressure-sensitive adhesive composition (A) contained in the first pressure-sensitive adhesive layer)
80 parts by mass of 2-ethylhexyl acrylate as a non-crosslinkable acrylate unit, 17 parts by mass of isobornyl acrylate, and 3 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group are used in a known solvent weight. A polymerization reaction was performed by a legal method to obtain an acrylate copolymer solution. A pressure-sensitive adhesive solution containing this acrylic acid ester copolymer solution as a pressure-sensitive adhesive was used as a pressure-sensitive adhesive composition (A).
As a release sheet, a release film (38 μm RL-07 (L), manufactured by Oji F-Tex Co., Ltd.) provided with a release layer on a PET film was prepared, and the above-mentioned pressure-sensitive adhesive composition ( The solution of A) was applied with a knife coater, heated at 100 ° C. for 3 minutes to form an adhesive layer having a thickness of 100 μm, and compared with JIS-C-2138 using a dielectric constant measurement system (Toyo Technica Model 1260). When the dielectric constant was measured and detected, the relative dielectric constant ε ₁ at a frequency of 1 MHz was 2.6.

(Production of pressure-sensitive adhesive composition (B) contained in the second pressure-sensitive adhesive layer)
40 parts by mass of methyl acrylate and 40 parts by mass of butyl acrylate as non-crosslinkable acrylic ester units, and 20 parts by mass of 2-hydroxyethyl acrylate as an acrylic monomer unit having a crosslinkable functional group are obtained by a known solvent polymerization method. A polymerization reaction was performed to obtain an acrylate copolymer solution. A pressure-sensitive adhesive solution containing this acrylic acid ester copolymer solution as a pressure-sensitive adhesive was used as a pressure-sensitive adhesive composition (B).
As a release sheet, a release film (38 μm RL-07 (L), manufactured by Oji F-Tex Co., Ltd.) provided with a release layer on a PET film was prepared, and the above-mentioned pressure-sensitive adhesive composition ( The solution of B) was applied with a knife coater, 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. The relative dielectric constant ε ₂ at a frequency of 1 MHz was 5.4. It was.

(Production of pressure-sensitive adhesive composition (C) contained in the first pressure-sensitive adhesive layer)
80 parts by mass of 2-ethylhexyl acrylate, 17 parts by mass of isobornyl acrylate, and 3 parts by mass of 4-hydroxybutyl acrylate were polymerized by a known bulk polymerization method to obtain an acrylate copolymer. A pressure-sensitive adhesive prepared by adding 30 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of isooctyl acrylate, and 0.5 parts by mass of a photopolymerization initiator as a reactive diluent to 100 parts by mass of the acrylate copolymer. The syrup was used as an adhesive composition (C).
As a release sheet, a release film (38 μm RL-07 (L), manufactured by Oji F-Tex Co., Ltd.) provided with a release layer on a PET film was prepared, and the above-mentioned pressure-sensitive adhesive composition ( The syrup of C) was coated with a knife coater and irradiated with an integrated light amount of 1000 mJ / cm ² while cooling with a UV irradiator under a nitrogen atmosphere to form an adhesive layer having a thickness of 100 μm. When the relative permittivity of this pressure-sensitive adhesive layer was measured based on JIS-C-2138 using a dielectric constant measurement system (Toyo Technica 1260 type) and detected, the relative permittivity ε ₁ at a frequency of 1 MHz was 2.4. It was.

(Production of pressure-sensitive adhesive composition (D) contained in the second pressure-sensitive adhesive layer)
40 mass parts of methyl acrylate and 40 mass parts of butyl acrylate as non-crosslinkable acrylic ester units, and 20 mass parts of 2-hydroxyethyl acrylate as an acrylic monomer unit having a crosslinkable functional group are obtained by a known bulk polymerization method. A polymerization reaction was performed to obtain an acrylate copolymer. An adhesive syrup 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 this acrylate copolymer was used as an adhesive composition (D).
As a release sheet, a release film (38 μm RL-07 (L), manufactured by Oji F-Tex Co., Ltd.) provided with a release layer on a PET film was prepared, and the above-mentioned pressure-sensitive adhesive composition ( The syrup of D) was applied with a knife coater and irradiated with an integrated light amount of 1000 mJ / cm ² while cooling with a UV irradiator under a nitrogen atmosphere to form an adhesive layer having a thickness of 100 μm. When the relative permittivity of this pressure-sensitive adhesive layer was measured based on JIS-C-2138 using a permittivity measurement system (Toyo Technica Model 1260), the relative permittivity ε ₁ at a frequency of 1 MHz was 5.8. It was.

(Example 1) Production of laminated adhesive sheet In order to produce a laminated adhesive sheet having a relative dielectric constant of 3.5 using the adhesive compositions (A) and (B), using the formula (1), The thickness ratio between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer was calculated. Since the calculated thickness ratio was “(thickness of the first pressure-sensitive adhesive) :( thickness of the second pressure-sensitive adhesive layer) = 1: 1”, the first pressure-sensitive adhesive layer and the first pressure-sensitive adhesive layer were A second pressure-sensitive adhesive layer was formed.

As a first release sheet, a release film (Oji F-Tex Co., Ltd., 38 μm RL-07 (L)) provided with a release agent layer on a PET film was prepared, and the release agent layer of the first release sheet was The solution of the pressure-sensitive adhesive composition (A) was applied with a knife coater and heated at 100 ° C. for 3 minutes to form a first pressure-sensitive adhesive layer having a thickness of 50 μm.

As the second release sheet, a release film (38 μm RL-07 (L) manufactured by Oji F-Tex Co., Ltd.) provided with a release agent layer on a PET film was prepared, and the release agent layer of the second release sheet was The solution of the pressure-sensitive adhesive composition (B) was applied with a knife coater and heated at 100 ° C. for 3 minutes to form a second pressure-sensitive adhesive layer having a thickness of 50 μm.

The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer were stacked and pressed together so that they were in contact with each other. Thus, the laminated adhesive sheet with a peeling sheet whose thickness of an adhesive layer is 100 micrometers was obtained.

(Example 2)
In order to produce a laminated adhesive sheet having a relative dielectric constant of 4.3 using the adhesive compositions (A) and (B), the first adhesive layer and the second adhesive The thickness ratio of the pressure-sensitive adhesive layer was calculated. Since the calculated thickness ratio was “(thickness of first pressure-sensitive adhesive) :( thickness of second pressure-sensitive adhesive layer) = 1: 3”, the thickness of the first pressure-sensitive adhesive layer was 25 μm and the second A laminated pressure-sensitive adhesive sheet with a release sheet having a pressure-sensitive adhesive layer thickness of 100 μm was obtained in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer was changed to 75 μm.

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

(Example 4) Production of laminated adhesive sheet using UV curable adhesive composition In order to produce a laminated adhesive sheet having a relative dielectric constant of 3.5 using adhesive compositions (C) and (D). In addition, the ratio of the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer was calculated using the formula (1). The ratio of the calculated thickness was “(thickness of the first pressure-sensitive adhesive increase) :( thickness of the second pressure-sensitive adhesive layer) = 0.9: 1.1”. An adhesive layer and a second adhesive layer were formed.

As a first release sheet, a release film (Oji F-Tex Co., Ltd., 38 μm RL-07 (L)) provided with a release agent layer on a PET film was prepared, and the release agent layer of the first release sheet was A syrup of the pressure-sensitive adhesive composition (C) was applied with a knife coater, and irradiated with an integrated light amount of 1000 mJ / cm ² while being cooled with a UV irradiator in a nitrogen atmosphere to form a pressure-sensitive adhesive layer having a thickness of 45 μm.

As the second release sheet, a release film (38 μm RL-07 (L) manufactured by Oji F-Tex Co., Ltd.) provided with a release agent layer on a PET film was prepared, and the release agent layer of the second release sheet was The solution of the pressure-sensitive adhesive composition (D) was applied with a knife coater, and irradiated with an integrated light amount of 1000 mJ / cm ² while being cooled with a UV irradiator in a nitrogen atmosphere to form a pressure-sensitive adhesive layer having a thickness of 55 μm.

The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer were stacked and pressed together so that they were in contact with each other. Thus, the laminated adhesive sheet with a peeling sheet whose thickness of an adhesive layer is 100 micrometers was obtained.

(Example 5)
In order to produce a laminated adhesive sheet having a dielectric constant of 4.4 using the adhesive compositions (C) and (D), the first adhesive layer and the second adhesive The thickness ratio of the pressure-sensitive adhesive layer was calculated. Since the calculated thickness ratio was “(thickness of the first pressure-sensitive adhesive) :( thickness of the second pressure-sensitive adhesive layer) = 1: 4”, the thickness of the first pressure-sensitive adhesive layer was set to 20 μm and the second thickness. A laminated pressure-sensitive adhesive sheet with a release sheet having a pressure-sensitive adhesive layer thickness of 100 μm was obtained in the same manner as in Example 4 except that the thickness of the pressure-sensitive adhesive layer was changed to 80 μm.

(Example 6)
In order to produce a laminated pressure-sensitive adhesive sheet having a relative dielectric constant of 3.0 using the pressure-sensitive adhesive compositions (C) and (D), the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are expressed using the formula (1). The thickness ratio of the pressure-sensitive adhesive layer was calculated. Since the calculated thickness ratio was “(thickness of the first pressure-sensitive adhesive increase) :( thickness of the second pressure-sensitive adhesive layer) = 6.5: 3.5”, the thickness of the first pressure-sensitive adhesive layer was A laminated pressure-sensitive adhesive sheet with a release sheet having a pressure-sensitive adhesive layer thickness of 100 μm was obtained in the same manner as in Example 4 except that the thickness of the second pressure-sensitive adhesive layer was changed to 65 μm and 35 μm.

(Measurement of relative permittivity)
When the relative dielectric constant at a frequency of 1 MHz of the laminated adhesive sheet obtained in the example was measured, the results shown in Table 1 were obtained. The theoretical relative dielectric constant is a value obtained by the equation (1).

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. Further, the epsilon _n, represents the dielectric constant of the adhesive layer, d _n represents the thickness of each adhesive layer. Note that n represents the number of pressure-sensitive adhesive layers.

From the results in Table 1, the relative dielectric constant obtained from the equation (1) and the measured relative dielectric constant are in good agreement. Thus, by using the calculation formula (1), it becomes possible to easily manufacture a laminated adhesive sheet having a desired relative dielectric constant.

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

(Preparation of pressure-sensitive adhesive composition (1))
40 parts by mass of methyl acrylate and 40 parts by mass of butyl acrylate as non-crosslinkable acrylic ester units, and 20 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group are obtained by a known solvent polymerization method. A polymerization reaction was performed to obtain an acrylate copolymer solution. A pressure-sensitive adhesive solution containing this acrylic acid ester copolymer solution as a pressure-sensitive adhesive was designated as pressure-sensitive adhesive composition (1).

(Preparation of pressure-sensitive adhesive composition (2))
As a non-crosslinkable acrylic ester unit, 60 parts by mass of 2-ethylhexyl acrylate, 38 parts by mass of isobornyl acrylate, and 2 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group are used. A polymerization reaction was performed by a legal method to obtain an acrylate copolymer solution. A pressure-sensitive adhesive solution containing the acrylic acid ester copolymer solution as a pressure-sensitive adhesive was designated as pressure-sensitive adhesive composition (2).

(Preparation of pressure-sensitive adhesive composition (3))
30 parts by mass of methyl acrylate, 60 parts by mass of butyl acrylate as non-crosslinkable acrylic ester units, and 10 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group are obtained by a known solvent polymerization method. A polymerization reaction was performed to obtain an acrylate copolymer solution. A pressure-sensitive adhesive solution containing this acrylic acid ester copolymer solution as a pressure-sensitive adhesive was designated as pressure-sensitive adhesive composition (3).

Example 7 Production of Laminated Adhesive Sheet 7 Having Three Adhesive Layers (1) Production of Second Adhesive Layer As a first release sheet, a release film provided with a release agent layer on a PET film [Oji Ftex Co., Ltd., 38 μm RL-07 (L)] was prepared, and the adhesive (2) solution was applied to the release agent layer of the first release sheet with a knife coater at 100 ° C. for 3 minutes. Heated to form a second pressure-sensitive adhesive layer. The relative dielectric constant ε _{r at} a frequency of 100 Hz of the formed second pressure-sensitive adhesive layer was 4.5.
In order to set the relative dielectric constant of the entire laminated adhesive sheet 7 to 5.5, from the thickness and relative dielectric constant of the first adhesive layer and the thickness and relative dielectric constant of the third adhesive layer, the formula (1) As a result of obtaining the optimum thickness of the second pressure-sensitive adhesive layer by using, the second pressure-sensitive adhesive (2) was applied so as to have a thickness of 51 μm.

(2) Production of first pressure-sensitive adhesive layer Release film comprising a release agent layer having a lower release property than the first release sheet on the PET film as the second release sheet [manufactured by Oji F-Tex Co., Ltd., 38 μm RL -07 (2)], and a solution of the above-mentioned adhesive (1) was applied to the release agent layer of the second release sheet with a knife coater so as to have a thickness of 25 μm, and 100 ° C. for 3 minutes. Heated to form a first pressure-sensitive adhesive layer. The relative dielectric constant ε _{r at} a frequency of 100 Hz of the formed first pressure-sensitive adhesive layer was 7.1.

(3) Production of third pressure-sensitive adhesive layer As a third release sheet, the same release film as the first release film [manufactured by Oji F-Tex Co., Ltd., 38 μm RL-07 (L)] was prepared. A solution of the pressure-sensitive adhesive (1) was applied to the release agent layer of the release sheet with a knife coater so as to have a thickness of 25 μm, and heated at 100 ° C. for 3 minutes to form a third pressure-sensitive adhesive layer. The relative dielectric constant ε _{r at} a frequency of 100 Hz of the formed third pressure-sensitive adhesive layer was 7.1.

(4) Production of laminated pressure-sensitive adhesive sheet After the second pressure-sensitive adhesive layer and the first pressure-sensitive adhesive layer are in contact with each other and pressure-bonded, the first pressure-sensitive adhesive sheet is peeled off to expose the second pressure-sensitive adhesive layer. Then, the laminated adhesive sheet 7 with a release sheet was obtained after the second adhesive layer and the third adhesive layer were put in contact with each other and pressed. Table 2 shows the thickness and relative dielectric constant of each layer of the laminated adhesive sheet 7.

(Measurement of relative dielectric constant of laminated adhesive sheet)
When the relative dielectric constant at a frequency of 100 kHz of the laminated adhesive sheet 7 was measured, the relative dielectric constant ε _r of the obtained laminated adhesive sheet 7 at a frequency of 100 Hz was 5.4. Table 3 shows the hydrogen ports and measured values of the relative permittivity of the laminated adhesive sheet 7 at a frequency of 100 Hz.

As shown in Table 3, by forming a pressure-sensitive adhesive layer having a low relative dielectric constant on the second pressure-sensitive adhesive layer and adjusting the thickness thereof, the overall relative dielectric constant of the laminated pressure-sensitive adhesive sheet 7 is substantially close to the estimated value. Actual measurement values could be obtained. That is, it can be said that a laminated adhesive sheet having a desired relative dielectric constant was obtained.

(Example 8) Production of laminated adhesive sheet 8 Adhesive (1) for the first adhesive layer, adhesive (2) for the second adhesive layer, and adhesive (3) for the third adhesive layer. Using, the laminated adhesive sheet 8 was produced by the same method as Example 7. In order to set the relative dielectric constant of the laminated adhesive sheet 8 to 5.0, the thickness and relative dielectric constant of the first adhesive layer and the thickness and relative dielectric constant of the third adhesive layer are expressed by the formula (1). As a result of obtaining the optimal thickness of the second pressure-sensitive adhesive layer using the pressure-sensitive adhesive, the pressure-sensitive adhesive (2) was applied so as to have a thickness of 100 μm.

Example 9 Production of Laminated Adhesive Sheet 9 Adhesive (3) for the first adhesive layer, adhesive (1) for the second adhesive layer, and adhesive (2) for the third adhesive layer A laminated adhesive sheet 9 was produced in the same manner as in Example 8 except that it was used.
In order to set the relative dielectric constant ε _r of the entire laminated adhesive sheet 9 to 6.3, the thickness and relative dielectric constant of the first adhesive layer and the thickness and relative dielectric constant of the third adhesive layer As a result of obtaining the optimum thickness of the second pressure-sensitive adhesive layer using (1), the pressure-sensitive adhesive (1) was applied so as to have a thickness of 100 μm.
Table 4 shows the thickness and relative dielectric constant of each layer of the laminated adhesive sheets 8 and 9.

(Measurement of relative dielectric constant of laminated adhesive sheet)
When the relative permittivity of the laminated adhesive sheets 8 and 9 at a frequency of 100 kHz was measured, the results shown in Table 5 were obtained.

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

According to the present invention, it is possible to provide a method for controlling the relative dielectric constant more accurately in the laminated adhesive sheet. For this reason, in this invention, the lamination adhesive sheet which has a desired dielectric constant can be obtained. The laminated pressure-sensitive adhesive sheet of the present invention is useful for bonding optical members, for example, bonding of ITO films in a touch panel sensor, or bonding of a touch panel module and a liquid crystal module.

DESCRIPTION OF SYMBOLS 1 1st adhesive layer 2 2nd adhesive layer 3 3rd adhesive layer 5 Resin layer 10 Laminated adhesive sheet

Claims (20)

A laminated pressure-sensitive adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer, and an absolute value of a difference in relative dielectric constant at a frequency of 1 MHz between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer Is a laminated pressure-sensitive adhesive sheet, characterized by being 0.5 or more. A laminated pressure-sensitive adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer, wherein the first pressure-sensitive adhesive layer having a relative dielectric constant of less than 4 at a frequency of 1 MHz and a relative dielectric constant of 4 or more at a frequency of 1 MHz The laminated pressure-sensitive adhesive sheet according to claim 1, further comprising a second pressure-sensitive adhesive layer. The laminated pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the first dielectric layer has a relative dielectric constant of less than 3 at a frequency of 1 MHz. The laminated pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein each of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has a thickness of 10 µm or more. The laminated adhesive according to any one of claims 1 to 4, wherein a ratio of the thicknesses of the first adhesive layer and the second adhesive layer is 1:99 to 99: 1. Sheet. The laminated pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are acrylic pressure-sensitive adhesive layers. The laminated pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer contain (meth) acrylic acid ester. The laminated pressure-sensitive adhesive sheet according to any one of claims 1 to 7, further comprising a third pressure-sensitive adhesive layer. The laminated adhesive sheet according to any one of claims 1 to 8, further comprising a resin layer. The laminated adhesive sheet according to claim 9, wherein the resin layer is provided between the first adhesive layer and the second adhesive layer. The first pressure-sensitive adhesive layer is laminated on the resin layer, and the second pressure-sensitive adhesive layer is laminated on the opposite side of the resin layer via the first pressure-sensitive adhesive layer. The laminated pressure-sensitive adhesive sheet according to claim 9. The laminated adhesive sheet according to any one of claims 9 to 11, wherein the resin layer has a relative dielectric constant of 2 to 10 at a frequency of 1 MHz. A laminate comprising the laminated pressure-sensitive adhesive sheet according to any one of claims 1 to 12 attached to at least one optical member. The laminate according to claim 13, wherein at least one of the optical members is ITO glass or an ITO film. A method for adjusting the relative dielectric constant of a laminated adhesive sheet having at least two adhesive layers,
The laminated adhesive sheet has a first adhesive layer having a relative dielectric constant of less than 4 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,
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 adjusted to adjust the relative dielectric constant of the laminated adhesive sheet. A relative dielectric constant adjusting method characterized by the above. The relative dielectric constant and thickness of the first pressure-sensitive adhesive layer at a frequency of 1 MHz and the relative dielectric constant and thickness of the second pressure-sensitive adhesive layer at a frequency of 1 MHz are adjusted using the following formula (1). The relative dielectric constant adjusting method according to claim 15.

(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, d _n represents the thickness of each adhesive layer. Here, n represents the number of layers of the pressure-sensitive adhesive layer.) 17. The dielectric constant according to claim 16, wherein d ₁ to d _n are determined so as to be a specific ε under the condition where ε ₁ to ε _n are fixed in the formula (1). Rate adjustment method. In the formula (1), under conditions epsilon _n and d _n are fixed, and ε ₁ ~ ε _n-1, according to claim 16, characterized in that to determine the d ₁ ~ d _n-1 The relative dielectric constant adjustment method. 19. The relative dielectric constant adjustment method according to claim 16, wherein n is 2 in the formula (1). A method for producing a laminated adhesive sheet having at least two adhesive layers, wherein the relative dielectric constant of the laminated adhesive sheet is adjusted by the relative dielectric constant adjusting method according to any one of claims 16 to 19. A method for producing a laminated adhesive sheet.

Images