JP7001000B2 - Adhesive layer and laminate - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer and a laminate.

In recent years, in various fields, display devices such as liquid crystal displays (LCDs) and organic EL displays, and devices combining display devices such as touch panels and input devices have been widely used. Above all, the capacitive touch panel is rapidly becoming widespread because of its functionality. In the manufacture of these display devices and input devices, an adhesive layer is used for bonding optical members, and the pressure-sensitive adhesive layer is also used for bonding the display device and the input device.

In the capacitance touch panel, when a finger is brought close to the surface, the capacitance between a plurality of electrodes changes at the same time, and it is possible to detect the position with high accuracy by measuring the ratio of the amount of current. However, if this method is increased in size, the touch panel will malfunction more often. In order to deal with such a problem, it is considered to use a pressure-sensitive adhesive layer having a controlled relative permittivity. Among them, in the capacitive touch panel having an image display device and a touch panel, the touch panel is liable to malfunction due to electrical noise from the image display device. Therefore, the adhesive layer or the image used for bonding the image display device and the touch panel. As the pressure-sensitive adhesive layer used for bonding the members in the display device, it is considered to use a pressure-sensitive adhesive layer having a low relative permittivity. Especially in the case of organic EL displays, there has been an increasing demand in recent years to make the entire image display device with a touch panel thinner in order to take advantage of its characteristic thinness, and the adhesive layer used to bond the image display device and the touch panel is also made thinner. The relative permittivity is also required to be lower. Further, since the organic EL element is vulnerable to moisture, each member used in the organic EL display may be required to have low moisture permeability.

For example, Patent Document 1 discloses a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having a low relative permittivity. Patent Document 1 is obtained by polymerizing a monomer component containing 19 to 99.5% by weight of an alkyl (meth) acrylate having a branched alkyl group having 10 to 24 carbon atoms at the end of the ester group (meth). Adhesives containing acrylic polymers are disclosed.

Japanese Patent No. 6223500

However, when the present inventors apply the pressure-sensitive adhesive layer described in Patent Document 1 to an apparatus having a thin overall thickness, the pressure-sensitive adhesive layer is likely to be deformed and dents are conspicuous. I understood.
It has been found that the moisture permeability is not satisfactory in the device that requires lower moisture permeability.

Therefore, in order to solve the problems of the prior art, the present inventors have provided a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having a low relative permittivity, high hardness and low moisture permeability. We proceeded with the examination as a purpose.

As a result of diligent studies to solve the above problems, the present inventors have made a diene-based polymer having a number average molecular weight of 250 to 15,000 and having a 1,2-vinyl group based on a styrene-based block copolymer. By polymerizing a monomer having at least one reactive double bond in the molecule and a monofunctional monomer component of a pressure-sensitive adhesive composition containing a polymerization initiator as an essential component with a polymerization initiator, the specific dielectric constant is low. It has been found that a pressure-sensitive adhesive layer having high hardness and low moisture permeability can be obtained.
Specifically, the present invention has the following configurations.

[1] A pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive composition containing a styrene-based block copolymer, a pressure-sensitive adhesive, and a plasticizer.
The styrene-based block copolymer is an ABA type triblock copolymer, A is a block obtained by polymerizing styrene, and B is a copolymer of at least one selected from ethylene, propylene and butene. It is a thermoplastic elastomer that has been made to
An aliphatic hydrocarbon selected from polybutene-based compounds, polyisobutylene-based compounds, polyisobutylene-based compounds, paraffin-based or naphthen-based system oils, wherein the plasticizer is a liquid at room temperature (23 ° C.).
A pressure-sensitive adhesive layer that satisfies the following physical property groups (1) and (2).
Physical property group (1): The shear storage elastic modulus G'measured at 23 ° C. and a frequency of 1 Hz is 1 × ¹⁰⁶ [Pa] or more, and the shear storage elastic modulus G'measured at 75 ° C. and a frequency of 1 Hz is 1. × 10 ⁵ [Pa] or more.
Physical property group (2): Moisture permeability measured according to JIS Z 0208 "Permeability test method for moisture-proof packaging material" when the pressure-sensitive adhesive layer composed of only the pressure-sensitive adhesive composition has a thickness of 100 μm ² -It is 24 hours or less.
[2] The pressure-sensitive adhesive composition further contains a diene-based polymer having a 1,2-vinyl group, a monomer having at least one reactive double bond in the molecule, and a polymerization initiator [1]. The pressure-sensitive adhesive layer described in.
[3] The pressure-sensitive adhesive layer according to [2], wherein the diene-based polymer having a 1,2-vinyl group is a polymer having a non-conjugated diene structure in the molecule.
[4] The pressure-sensitive adhesive layer according to [2] or [3], wherein the monomer having at least one reactive double bond in the molecule is a (meth) acrylic acid ester or an aromatic compound.
[5] The pressure-sensitive adhesive layer according to any one of [1] to [4], which has a relative permittivity of 3.0 or less.
[6] The pressure-sensitive adhesive layer according to any one of [1] to [5], which has a layer thickness of 5 μm to 200 μm.
[7] Two release sheets are laminated with the pressure-sensitive adhesive layer according to any one of [1] to [6] interposed therebetween, and the two release sheets have different peeling forces from the pressure-sensitive adhesive layer. Different laminates.
[8] A laminate in which a transparent base material is laminated on one side and a release sheet is laminated on the other side with the pressure-sensitive adhesive layer according to any one of [1] to [6] interposed therebetween.

According to the present invention, it is possible to provide a pressure-sensitive adhesive layer having a low relative permittivity, a high elastic modulus, and a low moisture permeability.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments and specific examples, but the present invention is not limited to such embodiments. In addition, the numerical range represented by using "-" in this specification means the range including the numerical values before and after "-" as the lower limit value and the upper limit value.

As used herein, "(meth) acrylic acid" represents both acrylic acid and / or methacrylic acid. Further, in the present specification, "monomer" and "monomer" are synonymous.

(Adhesive layer)
The present invention is a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive composition containing a styrene-based block copolymer, a pressure-sensitive adhesive, and a plasticizer.
The styrene-based block copolymer is an ABA type triblock copolymer, A is a block obtained by polymerizing styrene, and B is a polymer obtained from at least one selected from ethylene, propylene and butene. It is a thermoplastic elastomer that has been made to
An aliphatic hydrocarbon selected from polybutene-based compounds, polyisobutylene-based compounds, polyisobutylene-based compounds, paraffin-based or naphthen-based system oils, wherein the plasticizer is a liquid at room temperature (23 ° C.).
An adhesive layer satisfying the following physical property groups (1) and (2).
Physical property group (1): The shear storage elastic modulus G'measured at 23 ° C. and a frequency of 1 Hz is 1 × ¹⁰⁶ [Pa] or more, and the shear storage elastic modulus G'measured at 75 ° C. and a frequency of 1 Hz is 1. × 10 ⁵ [Pa] or more.
Physical property group (2): Moisture permeability measured according to JIS Z 0208 "Permeability test method for moisture-proof packaging material" when the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition has a thickness of 100 μm ² -It is 24 hours or less.

By having the above-mentioned structure, the pressure-sensitive adhesive layer of the present invention can form a pressure-sensitive adhesive layer having a low relative permittivity, high hardness and low moisture permeability.
Usually, when forming the pressure-sensitive adhesive layer used for optical applications, a crosslinkable acrylic polymer (base polymer) having excellent transparency is used. In order to reduce the relative permittivity, it is considered to change the structure of such a crosslinkable acrylic polymer (base polymer), but as long as the crosslinkable acrylic polymer is used, high hardness and low moisture permeability can be obtained. It was difficult to combine. However, after diligent studies, the present inventors have decided to use a styrene-based block copolymer as a base instead of changing the structure of the crosslinkable acrylic polymer (base polymer) to obtain a ratio of the pressure-sensitive adhesive layer. It has been found that the dielectric constant can be lowered, and high hardness and low moisture permeability can be improved. As described above, the present invention has succeeded in combining low relative permittivity with high hardness and low moisture permeability in the pressure-sensitive adhesive layer by using a styrene-based block copolymer as a base.

The relative permittivity of the pressure-sensitive adhesive layer at a frequency of 1 MHz is preferably 3.0 or less, and more preferably 2.9 or less. Further, it is better that the frequency dependence of the relative permittivity is small, and the absolute value of the difference between the relative permittivity at 1 MHz and the relative permittivity at 100 Hz is preferably 0 to 0.5, preferably 0 to 0.3. More preferred. By setting the relative permittivity of the pressure-sensitive adhesive layer within the above range, the pressure-sensitive adhesive layer is preferably used for bonding optical members constituting a display device equipped with a touch panel.
For the relative permittivity of the pressure-sensitive adhesive layer, a value calculated by the method specified in JIS C 2138 is used.

-Physical characteristics group (1)-
In the present invention, the pressure-sensitive adhesive layer satisfies the physical property group (1).
Physical property group (1): The shear storage elastic modulus G'measured at 23 ° C. and a frequency of 1 Hz is 1 × ¹⁰⁶ [Pa] or more, and the shear storage elastic modulus G'measured at 75 ° C. and a frequency of 1 Hz is 1. × 10 ⁵ [Pa] or more.
The shear storage elastic modulus G'measured at 23 ° C. and a frequency of 1 Hz is preferably 2.0 × ^{106 [Pa] or more, and is preferably 3.0 × 10 6 [} Pa] or more. More preferred. The upper limit of the shear storage elastic modulus G'measured at 23 ° C. and a frequency of 1 Hz of the pressure-sensitive adhesive layer is not particularly limited and may be, for example, 1.0 × ¹⁰⁸ [Pa] or less.
The shear storage elastic modulus G'measured at 75 ° C. and a frequency of 1 Hz is preferably 2.0 × ¹⁰⁵ [Pa] or more, and is preferably 3.0 × ¹⁰⁵ [Pa] or more. More preferred. The upper limit of the shear storage elastic modulus G'measured at 75 ° C. and a frequency of 1 Hz is not particularly limited, and can be, for example, 1.0 × ¹⁰⁸ [Pa] or less.
When the shear storage elastic modulus G'of the pressure-sensitive adhesive layer is within the above range, deformation and the like are unlikely to occur, and there is no problem that imprints are conspicuous. The problem that the imprints are conspicuous is that a laminate having a PET film / adhesive layer / glass structure is prepared, placed on a horizontal surface with the PET film side facing up, and a spherical weight is placed on the PET film for a certain period of time. It can be evaluated by whether or not it has imprints. The storage elastic modulus can be adjusted within the above range by adjusting the amount and type of the plasticizer and adding a curable component (addition of a monomer and an initiator, etc.).

-Physical characteristics group (2)-
In the present invention, the pressure-sensitive adhesive layer satisfies the physical property group (2).
Physical property group (2): The moisture permeability measured according to JIS Z 0208 "Permeability test method for moisture-proof packaging material" when the pressure-sensitive adhesive layer is 100 μm or less is 100 g / ^m 2.24 hr or less.
The moisture permeability measured according to JIS Z 0208 "Permeability test method for moisture-proof packaging material" when the pressure-sensitive adhesive layer is 100 μm is more preferably 80 g / ^m 2.24 hr or less, and 50 g / m. It is ^more preferably 2.24 hr or less. There is no particular lower limit for moisture permeability, but it can be 0.5 g / ^m 2.24 hr.
As long as the moisture permeability of the adhesive layer is within the above range, there is no problem that the touch panel or the image display device malfunctions or does not operate even in a device having no moisture resistance. As an alternative evaluation of whether or not a problem occurs in a device that does not have moisture resistance, the corrosiveness (presence or absence of loss of conductivity) of ITO (tin-doped indium oxide) used as a conductive layer of a transparent conductive film such as a touch panel is examined. Evaluation is possible by confirming.

The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer may contain a solvent, and in a state containing a solvent as described later, the solid content concentration is preferably 20 to 60% by mass, preferably 25 to 50% by mass. % Is more preferable.

<Styrene block copolymer>
The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the present invention contains a styrene-based block copolymer. As the styrene-based block copolymer, those having transparency to the extent that the visibility of the display device is not deteriorated are preferable.

The styrene-based block copolymer preferably contains a block obtained by polymerizing styrene and a block obtained by polymerizing at least one selected from ethylene, propylene and butene. The block obtained by polymerizing at least one selected from ethylene, propylene and butene may be a block obtained by polymerizing these hydrogenated substances. For example, styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene block copolymer, styrene-butadiene rubber (SBR), etc. may be mentioned. Be done. These styrene-based block copolymers may be used alone or in combination of two or more.
The block obtained by polymerizing styrene may be a block containing styrene as a main component, and may contain other components such as ethylene. The block obtained by polymerizing styrene preferably contains 90% by mass or more of a styrene-derived component, and more preferably 95% by mass or more. Further, the block obtained by polymerizing at least one selected from ethylene, propylene and butene may also contain other constituent components in the same manner.

The content of the styrene-polymerized block contained in the styrene-based block copolymer is preferably 10 to 50% by mass, preferably 10 to 40% by mass, based on the styrene-based block copolymer. More preferably, it is more preferably 10 to 35% by mass. The content of the styrene-polymerized block is the content of the styrene-polymerized block contained in the styrene-based block copolymer, and is different from the content of the styrene contained in the entire pressure-sensitive adhesive layer. It is a thing. In the present invention, desired hardness and moisture permeability can be obtained by setting the content of the styrene-polymerized block contained in the styrene-based block copolymer within the above range.

Further, the styrene-based block copolymer is preferably an ABA type triblock copolymer. Here, A of the ABA type triblock copolymer is a block obtained by polymerizing styrene, and B is a block obtained by polymerizing at least one selected from ethylene, propylene and butene. In addition, B may be a block of two or more random copolymers selected from ethylene, propylene and butene, and even when B is a random copolymer, the copolymer is ABA type. It is classified as a triblock copolymer. Further, B may be two or more block copolymers selected from ethylene, propylene and butene, and even when two kinds of blocks are contained in this way, the copolymer is AB-. It is classified as an A-type triblock copolymer.
Examples of B containing two types of blocks include styrene- (ethylene-propylene) -styrene type block copolymer (SEPS), styrene- (ethylene-butylene) -styrene type block copolymer (SEBS), and the like. Can be mentioned. These styrene-based block copolymers may be used alone or in combination of two or more.
Further, as the styrene-based block copolymer, an AB type diblock copolymer may be used in combination, and a mixture of an ABA type triblock copolymer and an AB type diblock copolymer may be used. ..
In that case, the blending amount of the AB type diblock copolymer with respect to 100 parts by mass of the ABA type triblock copolymer is preferably 0 to 50 parts by mass, preferably 0 to 30 parts by mass. Within this range, the desired hardness can be obtained.

Examples of the ABA type triblock copolymer include the styrene-based block copolymer of the following formula (1) (styrene-hydrogenated isoprene-styrene triblock copolymer) and the following formula (2). Styrene-based block copolymer (styrene- (ethylene / butylene) -styrene triblock copolymer), styrene-based block copolymer of the following formula (3) (styrene- (hydrogenated vinyl / isoprene) -styrene tri-polymer) Block copolymer) and the like.

In the formula (1), m represents the degree of polymerization and PS represents a block obtained by polymerizing styrene.
m can be calculated from the molecular weight of the styrene-based block copolymer.

In the formula (2), m and n each represent the degree of polymerization, and PS represents a block obtained by polymerizing styrene. m and n can be calculated from the molecular weight of the styrene-based block copolymer.

In the formula (3), m represents the degree of polymerization and PS represents a block obtained by polymerizing styrene.
m can be calculated from the molecular weight of the styrene-based block copolymer.

In the ABA type triblock copolymer, it is also preferable that A is a block polymerized with styrene and B is a block polymerized with hydrogenated isoprene.

The weight average molecular weight (Mw) of the styrene-based block copolymer is preferably 10,000 to 1,000,000, more preferably 50,000 to 800,000, and even more preferably 80,000 to 500,000. The weight average molecular weight (Mw) is calculated based on a calibration curve prepared by using a polystyrene standard material by gel permeation chromatography (GPC) measurement.

Examples of commercially available styrene-based block copolymers include SEP-type Septons 1001 and 1020, SEPS-type Septons 2002, 2004, 2005, 2006, 2007, 2063 and 2104, and SEBS-type Septons 8004, 8006, 8007. 8076 and 8104 (the above Septon series is manufactured by Kuraray), SEBS type tough tech H1221, H1662, H1052, H1053, H1041, H1051, H1517, H1043, H1272 and N504, SBBS type tough tech P1500, P2000 and JT83X (above above). The tough tech series can also be made by Asahi Kasei Corporation).

In the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer, the content of the styrene-based block copolymer may be 30% by mass or more, and 40% by mass or more, based on the pressure-sensitive adhesive composition. It is preferably 45% by mass or more, more preferably 45% by mass or more.
If the content of the styrene-based block copolymer is within the above range, the desired hardness can be obtained.

<Adhesive enhancer>
The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the present invention contains a pressure-sensitive adhesive. Aromatic polymers are preferable as the tackifier. That is, a polymer synthesized from an aromatic vinyl monomer is preferable.

Examples of the aromatic polymer that can be used include aromatic petroleum resin, styrene polymer, α-methylstyrene polymer, styrene- (α-methylstyrene) copolymer, and styrene-aliphatic hydrocarbon. Examples thereof include a system copolymer, a styrene- (α-methylstyrene) -aliphatic hydrocarbon-based copolymer, and a styrene-aromatic hydrocarbon-based copolymer.

Commercially available aromatic polymers include FMR-0150 (styrene-aromatic hydrocarbon copolymer_manufactured by Mitsui Kagaku Co., Ltd.) and FTR-6100 (styrene-aliphatic hydrocarbon-based copolymer_Mitsui Kagaku Co., Ltd.). , FTR-6110 (styrene-aliphatic hydrocarbon-based copolymer_manufactured by Mitsui Chemicals, Inc.), FTR-6125 (styrene-aliphatic hydrocarbon-based copolymer_manufactured by Mitsui Chemicals, Inc.), FTR-7100 (styrene). -(Α-Methylstyrene) -aliphatic hydrocarbon-based copolymer (manufactured by Mitsui Chemicals, Inc.), FTR-8100 (styrene-based polymer manufactured by Mitsui Chemicals, Inc.), FTR-8120 (styrene-based polymer manufactured by Mitsui Chemicals, Inc.), FTR-0100 (α-methylstyrene polymer_manufactured by Mitsui Kagaku Co., Ltd.), FTR-2120 (styrene- (α-methylstyrene) -based copolymer_manufactured by Mitsui Kagaku Co., Ltd.), FTR-2140 (styrene-( α-Methylstyrene) -based copolymer_manufactured by Mitsui Kagaku Co., Ltd.) can be used.

The weight average molecular weight (Mw) of the aromatic polymer as the tackifier is preferably 1000 or more and 10000 or less, and more preferably 2000 or more and 8000 or less. By setting the weight average molecular weight within the above range, the compatibility with the styrene-based block copolymer can be improved, and the desired adhesive performance can be obtained. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) and determined based on polystyrene. As the tackifier, the above-mentioned commercially available adhesive may be used, or one synthesized by a known method may be used.

The content of the tackifier in the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer is preferably 10 to 100 parts by mass, more preferably 15 to 80 parts by mass with respect to 100 parts by mass of the styrene-based block copolymer. preferable. By setting the content of the tackifier in the above range, desired tackling performance, hardness and moisture permeability can be obtained.

As the tackifier resin, a tackifier resin having a softening point of 100 ° C. or lower and a tackifier resin having a softening point of 120 ° C. or higher may be used in combination in order to exert adhesive strength at low temperature and cohesive strength at high temperature. The pressure-sensitive adhesive layer containing such a pressure-sensitive adhesive resin can be satisfactorily used in a wide temperature environment.

Further, as the tackifier other than the aromatic polymer, a known resin having a softening point such as a rosin resin or a terpene resin may be used. When a tackifier other than the aromatic polymer is used, it may be used alone, but it is preferable to use it in combination with the aromatic polymer. When used in combination with an aromatic polymer, the amount of a non-aromatic tackifier such as rosin or terpene to 100 parts by mass of the aromatic polymer is 0 to 50 parts by mass, preferably 0 to 30. The mass part is good. Within this range, desired transparency, adhesive performance, and hardness can be obtained.

<Plasticizer>
The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the present invention contains a plasticizer. The plasticizer is preferably an aliphatic hydrocarbon selected from polybutene-based compounds, polyisobutylene-based compounds, polyisobutylene-based compounds, paraffin-based or naphthen-based system oils, which are liquid at room temperature (20 ° C.). The fact that the plasticizer is liquid at room temperature (20 ° C.) means that the viscosity measured by a B-type viscometer measured at 20 ° C. is 30,000 mPa · s or less. The viscosity of the plasticizer is preferably 50 to 30,000 mPa · s, more preferably 100 to 20,000 mPa · s.

Although phthalates and the like can be used as the plasticizer, the above-mentioned aliphatic hydrocarbon is particularly preferable from the viewpoint of environment and safety.
The content of the plasticizer varies depending on the molecular weight of the styrene-based block copolymer used, but is preferably 10 to 90 parts by mass, preferably 15 to 80 parts by mass with respect to 100 parts by mass of the styrene-based block copolymer. It is more preferably 10 parts by mass, further preferably 15 to 70 parts by mass, and particularly preferably 20 to 60 parts by mass.

<Diene polymer having 1,2-vinyl group>
The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the present invention may contain a diene-based polymer having a 1,2-vinyl group. The number average molecular weight of the diene polymer having a 1,2-vinyl group is 250 to 15,000. When a diene polymer having a 1,2-vinyl group is blended, it is preferable to simultaneously blend a monomer having at least one reactive double bond in the molecule described later and a polymerization initiator.

The diene-based polymer is preferably a polymer of alkaziene. Among them, the diene-based polymer is preferably a polymer having a non-conjugated diene structure in the molecule, and particularly preferably a polymer having a non-conjugated alkadiene structure in the molecule.

The diene polymer has a 1,2-vinyl group (1,2-vinyl structure). That is, the diene-based polymer is a polymer of alkaziene having 2,3-diene and 1,2-vinyl groups.

The alkaziene monomer unit is preferably a monomer unit derived from alkaziene having 4 to 12 carbon atoms. Examples of the alkaziene having 4 to 12 carbon atoms include butadiene, isoprene, pentadiene, hexadiene, cyclopentadiene, cyclohexadiene, and isobutylene. Among them, the alkaziene is preferably an alkaziene having 4 to 8 carbon atoms, and particularly preferably butadiene. That is, the diene-based polymer is preferably a butadiene-based polymer.

The butadiene-based polymer may be a polymer composed of a monomer unit derived from butadiene, or may be a copolymer containing another monomer unit. When the butadiene polymer is a copolymer, other monomer units constituting the butadiene polymer include, for example, styrene, (meth) acrylic acid, (meth) acrylic acid derivative, unsaturated carboxylic acid, and the like. Examples thereof include unsaturated carboxylic acid derivatives.

The number average molecular weight of the diene polymer may be 250 or more, preferably 500 or more, and more preferably 800 or more. The number average molecular weight of the diene polymer may be 15,000 or less, preferably 10,000 or less, more preferably 8,000 or less, and further preferably 6,000 or less. By setting the number average molecular weight of the diene polymer within the above range, it is possible to improve the step followability and durability of the pressure-sensitive adhesive layer. The number average molecular weight of the diene-based compound polymer is a value obtained by measuring by gel permeation chromatography (GPC) or a vapor pressure type molecular weight measurement method (VPO method).

The 1,2-vinyl bond amount (1,2-vinyl group ratio) of the diene-based polymer is preferably 10% or more, more preferably 20% or more with respect to the diene-based polymer.
The 1,2-vinyl bond amount (1,2-vinyl group ratio) referred to here is the ratio of the 1,2-vinyl structure to the molecular weight (number average molecular weight) of the entire diene polymer. That is, the vinyl group ratio is calculated by the following formula when the number average molecular weight of the diene polymer is Md and the molecular weight of the 1,2-vinyl group-containing unit in the diene polymer is Mv.
(Vinyl group ratio%) = Mv ÷ Md × 100
Assuming that the molecular weight of the vinyl group-containing unit is Ms, the following relationship holds.
(Number of 1,2-vinyl groups per molecular chain of diene polymer) = Md × (1,2-vinyl group ratio) ÷ Ms

The diene polymer is preferably liquid or oily at 20 ° C. The fact that the diene polymer is liquid or oily at 20 ° C means that the viscosity measured by a B-type viscometer at 20 ° C is 30,000 mPa · s or less. The viscosity of the diene polymer is preferably 500 to 30,000 mPa · s, more preferably 800 to 20,000 mPa · s.

The content of the diene-based polymer is preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, and 3 to 3 to 15 parts by mass with respect to 100 parts by mass of the above-mentioned styrene-based block copolymer. It is more preferably 12 parts by mass. By setting the content of the diene polymer within the above range, a monomer having at least one reactive double bond in the molecule described later and a polymerization initiator can be used while exhibiting the effect of lowering the specific dielectric constant. By blending at the same time, the vinyl group portion and the monomer can be reacted and crosslinked, and it becomes easy to obtain the desired hardness.
The diene-based polymer may contain one type alone, or may contain two or more types having different structures, number average molecular weights, and the like.

As the diene polymer, a commercially available product can be used. Examples of commercially available products include polybutadiene (manufactured by Total, Ricon 156, Ricon 157, Krasol LBH-P 2000, Krasol LBH-P 3000) and the like.
Further, the diene-based polymer can be produced by polymerization. The production method is not particularly limited, and can be appropriately selected from commonly used polymerization methods. Examples of the polymerization method include a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method.

<Monomer having at least one reactive double bond in the molecule>
The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the present invention may contain a monomer having at least one reactive double bond in the molecule. When the monomer is blended, it is necessary to provide a step of blending and curing the polymerization initiator described later at the same time. The curing step may be performed before or after bonding to the adherend. As the monomer having at least one reactive double bond in the molecule, one kind may be used alone or two or more kinds may be used in combination.

Among the monomers having at least one reactive double bond in the molecule, the monomer having only one reactive double bond in the molecule (hereinafter referred to as “monofunctional monomer”) For example, lauryl acrylate, isostearyl acrylate, isobornyl acrylate, styrene, α-methylstyrene and the like can be mentioned.
Commercially available products can be used as the monofunctional monomer. Examples of commercially available products include isostearyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., ISTA), isobornyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., IBXA) and the like.
Among the monomers having at least one reactive double bond in the molecule, the monomer having two or more reactive double bonds in the molecule (hereinafter referred to as "polyfunctional monomer") Examples thereof include diacrate of bisphenol A diglycidyl ether, diacrylate of propoxylated bisphenol A, diaclate of bisphenol F diglycidyl ether, polyethylene glycol diacrylate, and trimerol propanepropylene oxide-modified triacrylate.
Commercially available products can be used as the polyfunctional monomer. Examples of commercially available products include bifunctional monomer M211B (bisphenol A ethylene oxide-modified diacrylate) manufactured by Toa Synthetic Co., Ltd., bifunctional monomer M08 (bisphenol F ethylene oxide-modified diacrylate) manufactured by Toa Synthetic Co., Ltd. Bifunctional Monomer M240 (Polyethylene Glycol Diacrylate), Bifunctional Monomer A-BPP-3 (Propoxized Bisphenol A Diacrylate), Toa Synthetic Co., Ltd., Trifunctional Monomer M321 (Trimethylol Propanepropylene Oxide Modified) Triacrylate ° C) and the like.
Of the monomers having at least one reactive double bond in the molecule, isostearyl acrylate, isobornyl acrylate, styrene, and α-methylstyrene are particularly preferable from the viewpoint of compatibility with styrene-based block copolymers. ..

In the present invention, the content of the monomer having at least one reactive double bond in the molecule with respect to 100 parts by mass of the styrene-based block copolymer of the pressure-sensitive adhesive composition is preferably 0 to 80 parts by mass. It is particularly preferably 5 to 60 parts by mass. Further, a monofunctional monomer and a polyfunctional monomer may be used in combination.

<Initiator of polymerization>
The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the present invention contains the above-mentioned diene-based polymer having a 1,2-vinyl group and / or a monomer having at least one reactive double bond in the molecule. If so, it contains a polymerization initiator. The polymerization initiator initiates the polymerization of a diene polymer having a 1,2-vinyl group and / or a monomer having at least one reactive double bond in the molecule by irradiation with active energy rays or heating. It is preferable that the polymerization is started, and it is more preferable that the polymerization is started by irradiation with active energy rays. As the polymerization initiator, known agents such as a photopolymerization initiator can be used.
Here, the "active energy beam" means an electromagnetic wave or a charged particle beam having an energy quantum, and examples thereof include ultraviolet rays, electron beams, visible rays, X-rays, and ion beams. Among them, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable, from the viewpoint of versatility.

Examples of the polymerization initiator include an acetophenone-based initiator, a benzoin ether-based initiator, a benzophenone-based initiator, a hydroxyalkylphenone-based initiator, a thioxanthone-based initiator, an amine-based initiator, an acylphosphine oxide-based initiator, and the like. Be done.
Specific examples of the acetophenone-based initiator include diethoxyacetophenone and benzyldimethylketal.
Specific examples of the benzoin ether-based initiator include benzoin, benzoin methyl ether and the like.
Specific examples of the benzophenone-based initiator include benzophenone, methyl o-benzoylbenzoate, and the like.
Specific examples of the hydroxyalkylphenone-based initiator include 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF Japan Ltd., commercially available as IRGACURE184) and the like.
Specific examples of the thioxanthone-based initiator include 2-isopropylthioxanthone, 2,4-dimethylthioxanthone and the like.
Specific examples of the amine-based initiator include triethanolamine, ethyl 4-dimethylbenzoate and the like.
Specific examples of the acylphosphine oxide-based initiator include phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by BASF Japan Ltd., commercially available as IRGACURE819) and the like.

The content of the polymerization initiator in the pressure-sensitive adhesive composition is the content of the monomer or the case where the pressure-sensitive adhesive layer of the present invention is bonded to an adherend and then cured (hereinafter referred to as "post-curing"). It is appropriately selected according to the irradiation amount of the active energy ray and the like. Specifically, it is preferably 0.05 to 10% by mass, more preferably 0.1 to 5.0% by mass, based on the total mass of the monomer. If it is at least the above lower limit value, it can be adjusted to a desired hardness by post-curing, so that the workability is excellent. When it is not more than the above upper limit value, the molecular weight after post-curing is not reduced and the processability is excellent. As the polymerization initiator, one type may be used alone or two or more types may be used in combination, and when two or more types are used in combination, the total mass is preferably within the above range.

<Other ingredients>
The pressure-sensitive adhesive composition may contain components other than the above as long as the effects of the present invention are not impaired. Examples of other components include components known as additives for adhesives. For example, it can be selected from among antioxidants, metal corrosion inhibitors, silane coupling agents, ultraviolet absorbers, light stabilizers such as hindered amine compounds (HALS), and the like, if necessary. Further, dyes and pigments may be added for the purpose of coloring. Further, a cross-linking agent may be added.
Examples of the silane coupling agent include a mercaptoalkoxysilane compound (for example, a mercapto group-substituted alkoxy oligomer) and the like.
Examples of the ultraviolet absorber include benzotriazole-based compounds, benzophenone-based compounds, and triazine-based compounds. However, when ultraviolet rays are used as the active energy rays during post-curing, it is preferable to add them within a range that does not inhibit the polymerization reaction.
As the cross-linking agent, an isocyanate-based compound, an epoxy-based compound, a hydrogen-drawing initiator, or the like can be blended. In particular, a hydrogen-drawing initiator is preferable because even if there is no functional group, when hydrogen is attached to the carbon next to the heteroatom, the hydrogen is extracted by irradiating with an energy ray such as ultraviolet rays to generate radicals and react.
Further, in order to prevent the pressure-sensitive adhesive layer from deteriorating over time, it is preferable to add an anti-aging agent. By adding an anti-aging agent, it is possible to prevent a decrease in adhesive strength due to deterioration of the adhesive layer. The amount of the antioxidant added is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the rubber resin.
As the anti-aging agent, it is preferable to use the above-mentioned antioxidant, ultraviolet absorber, HALS and the like alone or in combination. Among them, the antioxidant is preferable as the antioxidant, and examples of the antioxidant used in this application include general phenolic antioxidants and phosphorus-based antioxidants. One type of these antioxidants may be used alone, or two or more types may be used in combination.

<Solvent>
The pressure-sensitive adhesive composition may further contain a solvent. In this case, the solvent can improve the coatability of the pressure-sensitive adhesive composition.
Examples of such a solvent include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane and methylcyclohexane; halogenated hydrocarbons such as dichloromethane, trichloroethane, trichloroethylene, tetrachloroethylene and dichloropropane; methanol. , Ethanol, propanol, isopropyl alcohol, butanol, isobutyl alcohol, diacetone alcohol and other alcohols; ethers such as diethyl ether, diisopropyl ether, dioxane, tetrahydrofuran; acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone and other ketones. Esters such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl butyrate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl Examples thereof include polyols such as ether and propylene glycol monomethyl ether acetate and derivatives thereof. Of these, toluene, which is a styrene-based block copolymer and has high solubility, is preferable.

One type of solvent may be used alone, or two or more types may be used in combination. The content of the solvent in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 25 parts by mass or more and 500 parts by mass or less, and 30 parts by mass or more and 400 parts by mass or less, with respect to 100 parts by mass of the styrene-based block copolymer. The following is more preferable.
The content of the solvent is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 80% by mass or less, based on the total mass of the pressure-sensitive adhesive composition.

(Manufacturing method of adhesive layer)
The method for producing the pressure-sensitive adhesive layer is not particularly limited.
The pressure-sensitive adhesive layer of the present invention may be composed of a pressure-sensitive adhesive layer and another layer, but it is preferably composed of only the pressure-sensitive adhesive layer. Examples of the other layer include a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition other than the above, a support, a release sheet, and the like. Examples of the support include plastic films such as polystyrene, styrene-acrylic copolymer, acrylic resin, polyethylene terephthalate, polycarbonate, polyether ether ketone, triacetyl cellulose; antireflection film, electromagnetic wave shielding film, polarizing plate film and the like. Optical film; etc.

The process for producing the pressure-sensitive adhesive layer preferably includes a step of applying the pressure-sensitive adhesive composition on the release sheet to form a coating film and a step of drying the solvent by heating the coating film. Further, when the above-mentioned diene polymer having a 1,2-vinyl group, a monomer having at least one reactive double bond in the molecule, and a polymerization initiator are blended, the polymerization initiator initiates photopolymerization. In the case of the agent, active energy ray irradiation may be performed after the heating and drying step. In this case, the post-curing property is lost. Therefore, if it is desired to have the post-curing property, it is better to omit the step of irradiating with active energy rays.

The coating of the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer can be carried out using a known coating device. Examples of the coating device 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, a curtain coater and the like.
Further, the coating film can be heated by using a known heating device such as a heating furnace or an infrared lamp.

The adhesive strength of the adhesive layer is not particularly limited as long as it does not peel off or float.

The thickness of the pressure-sensitive adhesive layer can be appropriately set according to the intended use, and is usually preferably in the range of 5 μm or more and 200 μm or less, more preferably 5 μm or more and 150 μm or less, and further preferably 5 μm or more and 100 μm or less. The thickness of the pressure-sensitive adhesive layer is preferably within the above range, preferably 5 μm or more and 50 μm or less, and particularly preferably 5 μm or more and 25 μm or less.

The haze of the pressure-sensitive adhesive layer is preferably 2.0%, more preferably 1.5% or less, and even more preferably 1.0% or less. Here, the haze of the pressure-sensitive adhesive layer is a value measured by a method according to JIS K 7136 with slide glass (product number: S9112) manufactured by Matsunami Glass Co., Ltd. bonded to both sides of the pressure-sensitive adhesive layer. Specifically, the adhesive layer is attached to a slide glass (product number: S9112) manufactured by Matsunami Glass Co., Ltd., and the slide glass is also attached to the opposite surface of the adhesive layer so that air and foreign matter do not enter. , Glass / adhesive layer / glass are laminated in this order to prepare a laminated body. This laminate is subjected to autoclave (pressure defoaming) treatment at 0.5 MPa and 40 ° C. for 30 minutes, and the haze value is measured using NDH4000 manufactured by Nippon Denshoku Kogyo Co., Ltd.

<Structure of adhesive layer>
The pressure-sensitive adhesive layer of the present invention may be a single layer composed of only the pressure-sensitive adhesive layer. Further, the pressure-sensitive adhesive layer may be a single-sided pressure-sensitive adhesive layer having a base material (preferably a transparent base material) on one side, or a double-sided pressure-sensitive adhesive layer having no base material. The double-sided pressure-sensitive adhesive layer includes a single pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive layer, a multi-layered pressure-sensitive adhesive layer in which a plurality of pressure-sensitive adhesive layers are laminated, and another pressure-sensitive adhesive layer laminated between the pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer. A multi-layered pressure-sensitive adhesive layer, a multi-layered pressure-sensitive adhesive layer in which a support is laminated between the pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer, a pressure-sensitive adhesive layer laminated on one side of the support, and another pressure-sensitive adhesive layer laminated on the other side. Examples thereof include a multi-layered adhesive layer. When the double-sided pressure-sensitive adhesive layer has a support, it is preferable to use a transparent support as the support. As the support, a general film used in the optical field can be used as in the transparent substrate, and an optical film such as an antireflection film, an electromagnetic wave shielding film, and a polarizing plate film can be used. Since such a double-sided pressure-sensitive adhesive layer is also excellent in transparency of the pressure-sensitive adhesive layer as a whole, it can be suitably used for adhesion between optical members.

When the pressure-sensitive adhesive layer of the present invention is a single-sided pressure-sensitive adhesive layer, as shown in FIG. 1, a transparent base material 12a may be provided on one side of the pressure-sensitive adhesive layer 11. In this case, it is preferable that the other surface of the pressure-sensitive adhesive layer 11 is covered with the release sheet 12b. When the pressure-sensitive adhesive layer is used, the release sheet 12b is peeled off and attached so that the pressure-sensitive adhesive layer 11 adheres to a desired adherend. In the case of a pressure-sensitive adhesive layer in which a diene polymer having a 1,2-vinyl group and / or a monomer having at least one reactive double bond in the molecule is blended to impart post-curability, the pressure-sensitive adhesive layer is subsequently activated. Post-curing by irradiating with energy rays. As the transparent substrate, a general film used in the optical field such as a polyethylene terephthalate film, an acrylic film, a polycarbonate film, a triacetyl cellulose film, and a cycloolefin polymer film can be used. Further, an easy-adhesive layer may be provided on the pressure-sensitive adhesive layer side of these transparent substrates. Further, a functional layer such as a hard coat layer, an antireflection layer, an antifouling layer, and an ultraviolet absorbing layer may be provided on the opposite surface of the adhesive layer of the transparent base material.

The present invention may relate to a pressure-sensitive adhesive layer with a release sheet provided with release sheets on both surfaces of the pressure-sensitive adhesive layer. When the release sheets are provided on both surfaces of the pressure-sensitive adhesive layer of the present invention, it is preferable to have the release sheets 12a and 12b on both surfaces of the pressure-sensitive adhesive layer 11 as shown in FIG.

The release sheet is a removable laminated sheet having a release sheet base material and a release agent layer provided on one side of the release sheet base material, or a polyolefin film such as a polyethylene film or a polypropylene film as a low-polarity base material. Can be mentioned.
Papers and polymer films are used as the base material for the release sheet in the releaseable laminated sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition-type or condensation-type silicone-based release agent or a long-chain alkyl group-containing compound is used. In particular, a highly reactive additive silicone-based release agent is preferably used.
Specific examples of the silicone-based release agent include BY24-4527, SD-7220, etc. manufactured by Toray Dow Corning Silicone Co., Ltd., KS-3600, KS-774, X62-2600, etc. manufactured by Shin-Etsu Chemical Co., Ltd. Can be mentioned. Further, it is preferable that the silicone-based release agent contains a silicone resin which is an organic silicon compound having SiO2 unit and (CH3) 3SiO1 / 2 unit or CH2 = CH (CH3) SiO1 / 2 unit. Specific examples of the silicone resin include BY24-843, SD-7292, SHR-1404, etc. manufactured by Toray Dow Corning Silicone Co., Ltd., KS-3800, X92-183 manufactured by Shin-Etsu Chemical Co., Ltd., and the like.
A commercially available product may be used as the peelable laminated sheet. Examples thereof include a heavy separator film, which is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Film Co., Ltd., and a light separator film, which is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Film Co., Ltd. can.

When the pressure-sensitive adhesive layer of the present invention is a double-sided pressure-sensitive adhesive layer, it is preferable to have a pair of release sheets having different peeling forces. That is, it is preferable that the release sheet has different peelability between the release sheet 12a and the release sheet 12b in order to facilitate the release. When the peelability from one side and the peelability from the other side are different, it becomes easy to peel off only the peeling sheet having the higher peeling property first. In that case, the peelability of the release sheet 12a and the release sheet 12b may be adjusted according to the bonding method and the bonding order.

Further, the present invention may relate to a pressure-sensitive adhesive layer with a transparent film provided with a transparent film on at least one surface of the pressure-sensitive adhesive layer. In this case, the transparent film is preferably at least one selected from a polyethylene terephthalate film, an acrylic film, a polycarbonate film, a triacetyl cellulose film and a cycloolefin polymer film. The pressure-sensitive adhesive layer with a transparent film may be a sheet in which a transparent film / a pressure-sensitive adhesive layer / a release sheet are laminated in this order. Further, at least one surface of the pressure-sensitive adhesive layer may be a polarizing plate film such as a PVA layer resin containing a polarizing element, a retardation film, or a functional film such as a light diffusing film.

(How to use the adhesive layer)
When the pressure-sensitive adhesive layer of the present invention is used, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer is brought into contact with the surface of the adherend in an exposed state. Since the pressure-sensitive adhesive layer of the present invention has high hardness and poor wettability, the above-mentioned diene-based polymer having a 1,2-vinyl group, a monomer having at least one reactive double bond in the molecule, and polymerization In the case of blending an initiator, if the step of adhering it to the adherend and then curing it is performed, the wettability to the adherend is increased and the adhesive strength is strengthened. If the post-curing property is not provided as described above, the adhesive layer is softened by heating and then attached to the adherend, or the adhesive layer is attached and then heat and pressure are applied. A bonding method such as a so-called hot melt adhesive or a heat seal adhesive may be carried out. As the heating method in this case, a known method such as a roll bonding method using a heating roll, a heating pressure crimping method using a hot press, an autoclave, or the like can be adopted. The temperature at the time of heating may be any temperature as long as it is a softening temperature, but is preferably 50 ° C. or higher and 150 ° C. or lower, preferably 60 ° C. or higher and 120 ° C. or lower.

The adherend is preferably an optical member. Examples of the optical member include each constituent member in an optical product such as a touch panel and an image display device.
Examples of the constituent members of the touch panel include 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, and a transparent conductive film in which a transparent resin film is coated with a conductive polymer. Examples include hard coat films and fingerprint resistant films. Examples of the constituent members of the image display device include an antireflection film, an alignment film, a polarizing film, a retardation film, and a luminance improving film used in a liquid crystal display device and an organic EL display.
Examples of the material used for these members include glass, polycarbonate, polyethylene terephthalate, polymethylmethacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyimide, and cellulose acylate. A functional layer such as a hard coat layer may be provided on the side of these films in contact with the pressure-sensitive adhesive layer.

When the pressure-sensitive adhesive layer of the present invention is a double-sided pressure-sensitive adhesive layer, it can be used for bonding two adherends. In this case, the pressure-sensitive adhesive layer of the present invention is a bonding of ITO films inside a touch panel, a bonding of an ITO film and an ITO glass, a bonding of an ITO film of a touch panel and a liquid crystal panel or an organic EL panel, and a liquid crystal panel. Alternatively, it is used for bonding a member in an organic EL panel, for example, a polarizing plate, a cover glass and an ITO film, a cover glass and a decorative film, and the like.

(Manufacturing method of laminated body)
The present invention also relates to a method for producing a laminate. The method for producing the laminate preferably includes a step of bringing the above-mentioned pressure-sensitive adhesive layer into contact with the surface of the adherend.

Hereinafter, the features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as limiting by the specific examples shown below. In the following, Example 1 shall be read as Reference Example 1.

[Example 1]
<Preparation of adhesive solution for adhesive layer>
Styrene-based block copolymer (styrene- (ethylene / butylene) -styrene triblock copolymer) (Claret, Septon 8007) 100 parts by mass, styrene-based adhesive (FTR8120) 70 mass A pressure-sensitive adhesive composition consisting of 50 parts by mass of a paraffin-based oil (Diana Process Oil PW-90 manufactured by Idemitsu Co., Ltd.) was dissolved in toluene and stirred until uniform, and the adhesive toluene having a solid content concentration of 45% by mass was stirred. A solution (adhesive solution for adhesive layer) was obtained. The weight average molecular weight (Mw) of the styrene-based block copolymer was converted to 120,000 by gel permeation chromatography (GPC) measurement using a polystyrene standard material. The solid content refers to a styrene-based block copolymer, a tackifier, and an oil component. The measurement conditions of gel permeation chromatography (GPC) are as follows.
Solvent: Tetrahydrofuran Column: Shodex KF801, KF803L, KF800L, KF800D (4 units manufactured by Showa Denko KK were connected and used)
Column temperature: 40 ° C
Sample concentration: 0.5% by mass
Detector: RI-2031plus (manufactured by JASCO)
Pump: RI-2080plus (manufactured by JASCO)
Flow rate (flow velocity): 0.8 ml / min Injection amount: 10 μl
Calibration curve: Standard polystyrene Shodex standard polystyrene (manufactured by Showa Denko KK) A calibration curve with 10 samples from Mw = 1320 to 2,500,000 was used.

<Preparation of adhesive layer>
The pressure-sensitive adhesive solution for the pressure-sensitive adhesive layer prepared above was dried on a second peeling sheet (manufactured by Oji F-Tex Co., Ltd., RL-07 (2)) as a heavy peeling side so as to have a thickness of 20 μm after drying with a knife coater. After coating, it was dried at 100 ° C. for 3 minutes to dry the solvent toluene to obtain a double-sided pressure-sensitive adhesive layer. A pressure-sensitive adhesive layer with a release sheet was obtained by laminating the obtained pressure-sensitive adhesive layer with a first release sheet (manufactured by Oji F-Tex Co., Ltd., RL-07 (L)) as a light release side.

<Manufacturing of laminated body>
The first release sheet is peeled off from the surface of the glass plate, and the adhesive layer covers the entire glass (length 90 mm × width 50 mm × thickness 0.5 mm) using a laminator (manufactured by Yubon Co., Ltd., IKO-650EMT). I stuck them together. After that, the second release sheet is peeled off, and a PET film having a length of 90 mm × width of 50 mm × thickness of 50 μm and an ITO film on one side is in contact with the surface of the exposed pressure-sensitive adhesive layer so that the pressure-sensitive adhesive layer and the ITO film come into contact with each other. It was placed in the above-mentioned laminator and bonded to each other, and an autoclave treatment (40 ° C., 0.5 MPa, 30 minutes) was carried out to obtain a laminated body.

[Example 2]
In the pressure-sensitive adhesive composition of Example 1, 6 parts by mass of a diene-based polymer (manufactured by Total, "Ricon 156") having a 1,2-vinyl group with respect to 100 parts by mass of the styrene-based copolymer was added intramolecularly. Add 30 parts by mass of a monomer having at least one reactive double bond (isobornyl acrylate (IBXA), manufactured by Osaka Organic Co., Ltd.) and 1 part by mass of a photopolymerization initiator (BASF Japan, manufactured by IRGACURE 184). A pressure-sensitive adhesive solution for the pressure-sensitive adhesive layer was obtained.

<Preparation of adhesive layer>
The pressure-sensitive adhesive solution for the pressure-sensitive adhesive layer prepared above is applied in the same manner as in Example 1, and ultraviolet rays are irradiated from the peeling sheet side on the light peeling side of the pressure-sensitive adhesive layer so that the integrated light amount becomes 3000 mJ / cm2. , An adhesive layer with a release sheet was obtained.

<Manufacturing of laminated body>
A laminate was obtained in the same manner as in Example 1 except that the autoclave treatment temperature was changed to 90 ° C.

[Example 3]
Except for adding 10 parts by mass of a monomer having at least two reactive double bonds in the molecule (bisphenol AEO modified diacrylate (Toagosei Co., Ltd., M211B)) to the pressure-sensitive adhesive composition of Example 2. Obtained a pressure-sensitive adhesive solution for a pressure-sensitive adhesive layer in the same manner as in Example 2.

<Preparation of adhesive layer>
The pressure-sensitive adhesive solution for the pressure-sensitive adhesive layer prepared above was used in the same manner as in Example 2 to obtain a pressure-sensitive adhesive layer with a release sheet.

<Manufacturing of laminated body>
A laminated body was obtained in the same manner as in Example 1 except that after the autoclave treatment, ultraviolet rays were irradiated from the glass surface side so that the integrated light amount was 3000 mJ / cm2.

[Comparison example]
A (meth) acrylic polymer solution having a weight average molecular weight of 800,000 was prepared with a composition ratio of 100 parts by mass of isodecyl acrylate (IDA) and 1 part by mass of 4-hydroxybutyl acrylate (HBA). In the obtained (meth) acrylic polymer solution, 0.5 part of the trimethylolpropane adduct of xylylene diisocyanate (manufactured by Mitsui Kagaku Co., Ltd., trade name D110N) was added as a cross-linking agent to 100 parts by mass of the solid content of the polymer. By blending by weight, a pressure-sensitive adhesive solution for forming a pressure-sensitive adhesive layer was obtained.

<Preparation of adhesive layer>
The pressure-sensitive adhesive solution for the pressure-sensitive adhesive layer prepared above was used in the same manner as in Example 1 to obtain a pressure-sensitive adhesive layer with a release sheet.

<Manufacturing of laminated body>
A laminated body was obtained in the same manner as in Example 1.

[evaluation]
<Shear storage elastic modulus G'>
Ten pressure-sensitive adhesive layers (one sheet of 20 μm) were superposed so that the pressure-sensitive adhesive layer was 200 μm, and a sample for measurement was prepared. In Examples 2 and 3, after superimposing before irradiating with ultraviolet rays, ultraviolet rays were irradiated so that the integrated light amount was 3000 mJ / cm ² .
The pressure-sensitive adhesive layer of the measurement sample is from 0 ° C to 150 ° C using a dynamic viscoelastic device Rheogel-E4000 (manufactured by UBM Co., Ltd.) under the conditions of solid shear mode, frequency 1 Hz, and strain 0.1%. The shear storage elastic modulus G'of the pressure-sensitive adhesive layer in the temperature range of 1 was measured.
The shear storage elastic moduli G'of the pressure-sensitive adhesive layer at 23 ° C. and 75 ° C. are shown in Table 1 below.

<Moisture permeability>
Five pressure-sensitive adhesive layers (one sheet of 20 μm) were superposed so that the pressure-sensitive adhesive layer was 100 μm, and a sample for measurement was prepared. In Examples 2 and 3, after superimposing before irradiating with ultraviolet rays, ultraviolet rays were irradiated so that the integrated light amount was 3000 mJ / cm ² .
Using the measurement sample thus prepared, the moisture permeability in an environment of 40 ° C. and 90% relative humidity RH was measured according to JIS Z 0208 “Permeability test method for moisture-proof packaging material”.

<Evaluation of imprints>
Using the laminate prepared above, the PET film was placed on a horizontal surface with the PET film facing up, a 500 g spherical weight was placed on the PET film for 30 minutes, and then the weight was removed for 10 minutes. After standing still, it was visually observed whether or not there was an indentation on the part on which the weight was placed, and the evaluation was made according to the following criteria.
⊚: No imprints at all ○: Imprints are visible when projected with transmitted light, although they are not visible visually.
×: Imprints are visible visually

<Evaluation of ITO corrosiveness>
Using the laminate prepared above, the resistance value of the ITO film of the laminate was first measured using a tester, and then left in a moist heat environment with a temperature of 60 ° C and a relative humidity of 90% for 240 hours for heat humidification treatment. did. Then, after the laminated body heat-humidified for 240 hours was left at 23 ° C. and a relative humidity of 50% for 24 hours, the resistance value of the ITO film was measured again, and (resistance value after treatment-resistance value before treatment) ÷ ( The rate of increase in the ITO film resistance value was obtained from the formula of resistance value before treatment) × 100, and evaluated according to the following criteria.

⊚: Increase rate of resistance value is less than 1% ○: Increase rate of resistance value is 1% or more and less than 3% ×: Increase rate of resistance value is 3% or more

<Relative permittivity>
The evaluation of the relative permittivity of the pressure-sensitive adhesive layer was carried out by the following procedure. The first release sheet and the second release sheet are peeled from the pressure-sensitive adhesive layer with a release sheet, sandwiched between two copper foils of the pressure-sensitive adhesive layer, and autoclaved (40 ° C., 0.5 MPa, 30 minutes). did. After that, the relative permittivity was measured based on JIS C 2138 by a dielectric measurement system (manufactured by Toyo Corporation, 1260 type). The frequency and measurement environment were measured under the following conditions.
Frequency: 1MHz
Measurement environment: 23 ° C, relative humidity 55%

From the above table, the pressure-sensitive adhesive layer obtained in the examples is a pressure-sensitive adhesive layer having a low relative permittivity, and has high hardness and low moisture permeability, so that it is hard to be dented and has excellent corrosiveness. ..
From the above table, the pressure-sensitive adhesive layer obtained in the examples had a high hardness, so that it was difficult to make dents. Further, since it has low moisture permeability, it is excellent in ITO corrosiveness. Furthermore, the relative permittivity was low and the frequency dependence was also small.

Claims (7)

A pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive composition containing a styrene-based block copolymer, a pressure-sensitive adhesive, and a plasticizer.
The pressure-sensitive adhesive composition further contains a diene-based polymer having a 1,2-vinyl group, a monomer having at least one reactive double bond in the molecule, and a polymerization initiator.
The styrene-based block copolymer is an ABA type triblock copolymer, A is a block obtained by polymerizing styrene, and B is a weight of at least one selected from ethylene, propylene and butene. A combined thermoplastic elastomer
An aliphatic hydrocarbon selected from polybutene-based compounds, polyisobutylene-based compounds, polyisobutylene-based compounds, paraffin-based or naphthen-based system oils, wherein the plasticizer is a liquid at room temperature (23 ° C.).
An adhesive layer satisfying the following physical property groups (1) and (2).
Physical property group (1): The shear storage elastic modulus G'measured at 23 ° C. and a frequency of 1 Hz is 1 × ¹⁰⁶ [Pa] or more, and the shear storage elastic modulus G'measured at 75 ° C. and a frequency of 1 Hz is 1. × 10 ⁵ [Pa] or more.
Physical property group (2): Moisture permeability measured according to JIS Z 0208 "Permeability test method for moisture-proof packaging material" when the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition has a thickness of 100 μm ² . It is 24 hours or less. The pressure-sensitive adhesive layer according to claim 1 , wherein the diene-based polymer having a 1,2-vinyl group is a polymer having a non-conjugated diene structure in the molecule. The pressure-sensitive adhesive layer according to claim 1 or 2 , wherein the monomer having at least one reactive double bond in the molecule is a (meth) acrylic acid ester or an aromatic compound. The pressure-sensitive adhesive layer according to any one of claims 1 to 3 , wherein the relative dielectric constant is 3.0 or less. The pressure-sensitive adhesive layer according to any one of claims 1 to 4 , wherein the layer thickness is 5 μm to 200 μm. A laminated body in which two release sheets are laminated with the pressure-sensitive adhesive layer according to any one of claims 1 to 5 interposed therebetween, and the two release sheets have different peeling powers from the pressure-sensitive adhesive layer. A laminate in which a transparent base material is laminated on one side and a release sheet is laminated on the other side with the pressure-sensitive adhesive layer according to any one of claims 1 to 5 interposed therebetween.