JP2023047297A - Adhesive sheet, optical member, and touch panel - Google Patents

Abstract

The present invention provides a pressure-sensitive adhesive sheet, an optical member, and a touch panel that can form a pressure-sensitive adhesive layer that does not easily deteriorate the appearance of a display device or an input device even under low pressure conditions. A pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer, and in the following low pressure test, the number of voids with a diameter of 300 μm or more is less than 10, and the number of voids with a diameter of 50 or more and less than 300 μm is 20. less than one. <Low Pressure Test> As a sample, a 5 cm×10 cm display panel having a laminated structure of glass plate/polarizing plate/adhesive layer/glass plate is prepared. The thickness of the glass plate is 700 µm, the thickness of the polarizing plate is 115 µm (polarizing plate 95 + polarizing plate glue 20) µm, and the thickness of the adhesive layer is 150 µm. The display panel is allowed to stand under heating and decompressing conditions of 23,800 Pa and 65° C. for 8 hours, and after 30 minutes under normal pressure and room temperature, the size and number of voids are visually measured. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to an adhesive sheet, an optical member, and a touch panel.

In recent years, display devices such as liquid crystal displays (LCDs) and input devices such as touch panels used in combination with such display devices have been widely used in various fields. In these display devices, input devices, and the like, adhesive sheets having an adhesive layer are used for bonding optical members together. For example, a transparent adhesive sheet is used for bonding a touch panel and various display members or optical members (see Patent Documents 1 to 3, for example).

Among them, in applications such as the production of capacitive touch panels, metal thin films such as ITO (indium tin oxide) films and metal oxide thin films (hereinafter, metal thin films and metal oxide thin films are collectively referred to as "metal thin films" There are cases where the adhesive sheet is attached directly to the adhesive sheet.

In recent years, in applications such as the production of capacitive touch panels, films with metal mesh wiring made by processing metals such as silver and copper into a mesh (metal mesh film ) or a film having a silver nanowire layer (AgNW layer) (silver nanowire film) is being used. Capacitive touch panels that use metal mesh films and silver nanowire films are input devices that take advantage of the characteristics of low-resistance metal wiring to provide high sensitivity and support a wide range of display sizes, from small to large. be.

When an optical member having metal wiring such as a metal mesh film or a silver nanowire film is pasted together via an adhesive sheet, the peripheral edge of the image display panel may be damaged due to stress strain added to the adhesive around the metal wiring. There is a problem that display unevenness is likely to occur in some areas. Therefore, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet to which the optical member having the metal wiring is adhered is required to have flexibility for relieving stress with the metal wiring in order to prevent display unevenness.

JP 2003-238915 A JP-A-2003-342542 Japanese Patent Application Laid-Open No. 2004-231723

However, in order to prevent display unevenness, display devices and input devices that include optical members bonded together using a highly flexible adhesive sheet, for example, under low pressure conditions such as manufacturing processes, cargo compartments of passenger aircraft, and high altitudes. There is a problem that the appearance is deteriorated under the condition.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive sheet suitable for laminating metal mesh films and the like, which does not easily deteriorate the appearance of display devices and input devices even under low pressure conditions.
Another object of the present invention is to provide a high-performance optical member and a touch panel which are provided with the pressure-sensitive adhesive sheet and which are less likely to deteriorate in appearance even under low-pressure conditions.

A first aspect of the present invention provides an adhesive sheet having an adhesive layer. In the pressure-sensitive adhesive sheet of the first aspect of the present invention, the number of voids having a diameter of 300 μm or more is less than 10, and the number of voids having a diameter of 50 to less than 300 μm is less than 20 in the low pressure test described below.
<Low pressure test>
As a sample, a 5 cm×10 cm display panel having a laminated structure of glass plate/polarizing plate/adhesive layer/glass plate is prepared. The thickness of the glass plate is 700 µm, the thickness of the polarizing plate is 115 µm (polarizing plate 95 + polarizing plate glue 20) µm, and the thickness of the adhesive layer is 150 µm. The display panel is allowed to stand at 23,800 Pa under heating and decompressing conditions of 65° C. for 8 hours, and after 30 minutes under normal pressure and room temperature, the size and number of voids are visually measured.

In this specification, the pressure-sensitive adhesive sheet of the first aspect of the present invention may be referred to as "the pressure-sensitive adhesive sheet of the present invention", and the pressure-sensitive adhesive layer constituting the "pressure-sensitive adhesive sheet of the present invention" is referred to as "the pressure-sensitive adhesive sheet of the present invention". may be referred to as "adhesive layer".

In the adhesive sheet of the present invention, the number of voids having a diameter of 300 μm or more in the low pressure test is less than 10, and the number of voids having a diameter of 50 or more and less than 300 μm is less than 20. This is preferable from the viewpoint that the appearance of the display device and the input device is unlikely to be deteriorated.

In the pressure-sensitive adhesive sheet of the present invention, the maximum diameter of the voids in the low pressure test is preferably 600 µm or less. This configuration is preferable from the viewpoint that the appearance of the display device and the input device is less likely to deteriorate under low pressure conditions.

In the pressure-sensitive adhesive sheet of the present invention, the gel fraction of the pressure-sensitive adhesive layer of the present invention is preferably 50% or more. This configuration is preferable in that the appearance of the display device and the input device is less likely to deteriorate even under low pressure conditions.

In the pressure-sensitive adhesive sheet of the invention, the 300% tensile residual stress of the pressure-sensitive adhesive layer of the invention is preferably 5 N/cm ² or less. This configuration has high flexibility, and even when a film having metal wiring such as a metal mesh film or a silver nanowire film is bonded together, the stress with the metal wiring can be sufficiently relaxed to prevent display unevenness. It is preferable in that it can be

In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer of the present invention is preferably formed from a pressure-sensitive adhesive composition containing an acrylic polymer (A) and a hydrogenated polyolefin resin (B). Further, the pressure-sensitive adhesive layer of the present invention comprises a mixture of monomer components constituting the acrylic polymer (A) or a partial polymer of a mixture of monomer components constituting the acrylic polymer (A), and a hydrogenated polyolefin resin (B ) is also preferably formed by a pressure-sensitive adhesive composition containing.
In addition, in this specification, the adhesive composition which comprises the adhesive layer of this invention may be called "the adhesive composition of this invention."
In addition, unless otherwise specified, the term "acrylic polymer (A)" used in this specification means "acrylic polymer (A)" and "a mixture of monomer components constituting the acrylic polymer (A) or an acrylic polymer "partially polymerized mixture of monomer components constituting (A)".

The configuration that the pressure-sensitive adhesive composition of the present invention contains the acrylic polymer (A) can realize a highly flexible pressure-sensitive adhesive layer, and a film having metal wiring such as a metal mesh film or a silver nanowire film. Even in the case of lamination, it is preferable in that the stress with the metal wiring can be sufficiently relieved and display unevenness can be prevented.

In addition, the configuration in which the pressure-sensitive adhesive composition of the present invention contains the hydrogenated polyolefin resin (B) makes it possible to realize a pressure-sensitive adhesive layer that does not easily deteriorate the appearance of display devices and input devices even under low pressure conditions. and is preferred.

In the pressure-sensitive adhesive sheet of the present invention, the acrylic polymer (A) preferably contains a (meth)acrylic acid alkyl ester having an alkyl group having 8 or more carbon atoms as a constituent monomer component. In the specification of the present application, "(meth)acrylic acid alkyl ester having an alkyl group having 8 or more carbon atoms" may be referred to as "(meth)acrylic acid alkyl ester (A)".

In the pressure-sensitive adhesive composition of the present invention, the structure in which the acrylic polymer (A) contains the (meth)acrylic acid alkyl ester (A) as a constituent monomer component realizes a highly flexible pressure-sensitive adhesive layer. is possible, and even when a film having metal wiring such as a metal mesh film or a silver nanowire film is attached, the stress with the metal wiring can be sufficiently relaxed to prevent display unevenness, which is preferable. .

In the adhesive sheet of the present invention, the hydrogenated polyolefin resin (B) preferably contains hydrogenated polyolefin. The pressure-sensitive adhesive composition of the present invention contains a hydrogenated polyolefin as the hydrogenated polyolefin-based resin (B), thereby providing a pressure-sensitive adhesive layer that does not easily deteriorate the appearance of display devices and input devices even under low pressure conditions. It is preferable in that it can be realized.

In the pressure-sensitive adhesive sheet of the present invention, the hydrogenated polyolefin resin (B) preferably further contains a hydrogenated polyolefin polyol. This configuration is preferable in that it is possible to realize a pressure-sensitive adhesive layer that does not easily deteriorate the appearance of a display device or an input device even under low pressure conditions.

The thickness of the pressure-sensitive adhesive sheet of the present invention is preferably from 12 to 350 μm from the viewpoint of sufficiently relieving the stress with the metal wiring, preventing display unevenness, and easily maintaining an excellent appearance. .

A second aspect of the present invention is an optical member comprising at least the pressure-sensitive adhesive sheet of the present invention and a substrate, wherein the substrate has metal wiring on at least one surface thereof, and the metal wiring is provided on the surface of the substrate having the metal wiring. Provided is an optical member to which an adhesive sheet is attached. In this specification, the optical member of the fifth aspect of the present invention may be referred to as "the optical member of the present invention".

A third aspect of the present invention is a touch panel comprising at least the pressure-sensitive adhesive sheet of the present invention and a substrate, wherein the substrate has metal wiring on at least one side thereof, and on the surface of the substrate having the metal wiring, Provided is a touch panel to which the pressure-sensitive adhesive sheet is attached. In this specification, the touch panel of the third aspect of the present invention may be referred to as "the touch panel of the present invention".

In the optical member of the present invention and the touch panel of the present invention, the metal wiring is preferably metal mesh wiring or silver nanowires.

In the optical member of the present invention and the touch panel of the present invention, the appearance of a display device or an input device is less likely to deteriorate even under low pressure conditions, and metal wiring such as metal mesh wiring or silver nanowires is formed by a highly flexible adhesive sheet. is adhered, display unevenness is less likely to occur.

The pressure-sensitive adhesive sheet of the present invention can provide a display device or an input device whose appearance is less likely to deteriorate even under low-pressure conditions. Moreover, even when a film having metal wiring such as a metal mesh film or a silver nanowire film is attached, the stress with the metal wiring can be sufficiently relaxed to prevent display unevenness. Therefore, by bonding a metal mesh film or a silver nanowire film using the pressure-sensitive adhesive sheet of the present invention, even under low pressure conditions, the appearance is less likely to deteriorate and display unevenness is less likely to occur. The member can be efficiently manufactured.
Therefore, the pressure-sensitive adhesive sheet of the present invention is attached to an optical member having metal mesh wiring and a silver nanowire layer, particularly a transparent conductive film having a metal wiring layer such as a metal mesh film and a silver nanowire film. It can be preferably used for various purposes.

FIG. 1 is a schematic diagram showing a specific example of a preferred embodiment of the optical member of the present invention. FIG. 2 is a schematic diagram showing a specific example of a preferred embodiment of the touch panel of the present invention.

[1. Adhesive sheet, adhesive layer, and adhesive composition]
The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, the number of voids having a diameter of 300 μm or more in the following low pressure test is less than 10, and the number of voids having a diameter of 50 or more and less than 300 μm is 20. is less than
<Low pressure test>
As a sample, a 5 cm×10 cm display panel having a laminated structure of glass plate/polarizing plate/adhesive layer/glass plate is prepared. The thickness of the glass plate is 700 µm, the thickness of the polarizing plate is 115 µm (polarizing plate 95 + polarizing plate glue 20) µm, and the thickness of the adhesive layer is 150 µm. The display panel is allowed to stand at 23,800 Pa under heating and decompressing conditions of 65° C. for 8 hours, and after 30 minutes under normal pressure and room temperature, the size and number of voids are visually measured.

The reason why the appearance of display devices and input devices deteriorates under low-pressure conditions is thought to be the generation of fine air bubbles in the pressure-sensitive adhesive layer. Therefore, the configuration in which the number of voids having a diameter of 300 μm or more in the low pressure test is less than 10 and the number of voids having a diameter of 50 or more and less than 300 μm is less than 20 is effective even under low pressure conditions. This is preferable in that a pressure-sensitive adhesive layer that does not easily deteriorate the appearance of the input device can be realized.
In the adhesive sheet of the present invention, the number of voids having a diameter of 300 μm or more in the low pressure test is preferably 9 or less, more preferably 8, from the viewpoint that the appearance of the display device or input device is unlikely to deteriorate under low pressure conditions. 1 or less, more preferably 6 or less, and may be 5 or less, or 4 or less. The lower limit of the number of voids having a diameter of 300 μm or more in the low pressure test is not particularly limited, and 0 is most preferable.

In the adhesive sheet of the present invention, the number of voids having a diameter of 50 or more and less than 300 μm in the low pressure test is more preferably 15 or less from the viewpoint that the appearance of the display device or the input device is unlikely to deteriorate under low pressure conditions. The number is preferably 10 or less. The lower limit of the number of voids having a diameter of 50 or more and less than 300 μm in the low pressure test is not particularly limited, and is most preferably 0, but may be about 1.

In the pressure-sensitive adhesive sheet of the present invention, the maximum diameter of the voids in the low-pressure test is preferably 600 μm or less from the viewpoint that the appearance of the display device or the input device is unlikely to deteriorate under low-pressure conditions. From the viewpoint that the appearance of the display device and the input device is unlikely to deteriorate under low pressure conditions, the maximum diameter of the void in the low pressure test is preferably 300 μm or less, more preferably 250 μm or less, and still more preferably 200 μm or less, It may be 150 μm or less, or 100 μm or less.

In the pressure-sensitive adhesive sheet of the present invention, the number of voids having a diameter of 50 μm or less in the low-pressure test is not particularly limited from the viewpoint that the appearance of display devices and input devices is unlikely to deteriorate under low-pressure conditions. That is, the number of voids having a diameter of 50 μm or less may be 100 or less, although the effect on appearance is small.

In the pressure-sensitive adhesive sheet of the present invention, the diameter and the number of voids in the low-pressure test are specifically measured by the low-pressure test in Examples described later. ), the type and amount of the cross-linking agent, the type of the hydrogenated polyolefin resin (B), and the mixing ratio of the acrylic polymer (A) and the hydrogenated polyolefin resin (B). can do.

In the pressure-sensitive adhesive sheet of the present invention, the gel fraction (ratio of solvent-insoluble components) of the pressure-sensitive adhesive layer of the present invention is 50% or more from the viewpoint that the appearance of display devices and input devices is less likely to deteriorate under low pressure conditions. It is preferably 55% or more, still more preferably 60% or more, and may be 65% or more. In addition, the gel fraction of the pressure-sensitive adhesive layer of the present invention is preferably 90% or less, more preferably 85% or less, and 80% or less from the viewpoint of imparting flexibility to the pressure-sensitive adhesive layer and preventing display unevenness. may

Specifically, the gel fraction (proportion of solvent-insoluble components) is, for example, a value calculated by the following "Method for measuring gel fraction".

Adhesive layer: About 0.1 g was collected from the adhesive sheet, wrapped in a porous tetrafluoroethylene sheet (trade name “NTF1122”, manufactured by Nitto Denko Co., Ltd.) with an average pore size of 0.2 μm, and tied with a kite string. The weight at that time is measured, and the weight is taken as the weight before immersion. The weight before immersion is the total weight of the adhesive layer (the adhesive layer collected above), the tetrafluoroethylene sheet, and the kite string. Also, the total weight of the tetrafluoroethylene sheet and the kite string is measured, and this weight is taken as the weight of the package.
Next, the adhesive layer wrapped with a tetrafluoroethylene sheet and tied with a kite string (referred to as a "sample") is placed in a 50 ml container filled with ethyl acetate and allowed to stand at 23°C for 7 days. After that, remove the sample (after ethyl acetate treatment) from the container, transfer it to an aluminum cup, dry it in a dryer at 130 ° C. for 2 hours to remove ethyl acetate, measure the weight, and immerse the weight. Rear weight.
Then, the gel fraction is calculated from the following formula.
Gel fraction [% (% by weight)] = (XY) / (ZY) x 100

The gel fraction can be controlled by, for example, the monomer composition of the acrylic polymer (A) described below, the weight average molecular weight, the type and amount of cross-linking agent used (addition amount), and the like. Further, when the pressure-sensitive adhesive composition of the present invention is cured by ultraviolet irradiation, for example, since the carbon-carbon double bonds of the hydrogenated polyolefin resin (B) described later are reduced, polymerization inhibition is less likely to occur. , the decrease in gel fraction can be prevented.

The 300% tensile residual stress of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but it is excellent in flexibility, and even when a film having metal wiring such as a metal mesh film or a silver nanowire film is laminated, the metal wiring and the is preferably 5 N/cm ² or less, more preferably 4.5 N/cm ² or less, still more preferably 4 N/cm ² or less, in terms of being able to sufficiently relax the stress of and prevent display unevenness, It may be 3.5 N/cm ² or less, or 3 N/cm ² or less. The 300% tensile residual stress of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but may be 0.5 N/cm ² or more, or 1 N/cm ² or more from the viewpoint of adhesion reliability.

The 300% tensile residual stress is obtained by pulling the adhesive layer in the longitudinal direction to an elongation (strain) of 300% in an environment of 23 ° C., holding the elongation, and 300 seconds after the end of pulling. It is the value (N/cm ² ) obtained by dividing the tensile stress (N) applied to the pressure-sensitive adhesive layer by the initial cross-sectional area (cross-sectional area before pulling) of the pressure-sensitive adhesive layer. The initial elongation of the adhesive layer is 100%.

The 300% tensile residual stress of the pressure-sensitive adhesive layer of the present invention is specifically measured by the method described in Examples below. It can be adjusted by adjusting the type and blending amount of the cross-linking agent, the type of the hydrogenated polyolefin resin (B), the blending ratio of the acrylic polymer (A) and the hydrogenated polyolefin resin (B), and the like.

Although the pressure-sensitive adhesive layer of the present invention is not particularly limited, it is preferable that the dielectric constant is controlled to be low from the viewpoint of preventing malfunction of an optical member such as a touch panel having the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer of the present invention preferably has a dielectric constant of 3.5 or less, more preferably 3.4 or less, still more preferably 3.3 or less at a frequency of 1 MHz. Although the lower limit of the dielectric constant at a frequency of 1 MHz is not particularly limited, it is preferably 2.3 or higher, more preferably 2.4 or higher, and still more preferably 2.5 or higher.
Also, the dielectric constant at a frequency of 100 kHz is preferably 4.0 or less, more preferably 3.9 or less, and still more preferably 3.8 or less. Although the lower limit of the dielectric constant at a frequency of 100 kHz is not particularly limited, it is preferably 2.3 or higher, more preferably 2.4 or higher, and still more preferably 2.5 or higher.

The dielectric constant of the pressure-sensitive adhesive layer of the present invention can be determined, for example, by the monomer composition of the acrylic polymer (A) described later, the type of the hydrogenated polyolefin resin (B), the acrylic polymer (A) and the hydrogenated polyolefin resin (B ) can be adjusted by adjusting the compounding ratio.

The adhesive layer of the present invention has excellent transparency. Therefore, visibility and appearance through the pressure-sensitive adhesive layer are excellent. Thus, the pressure-sensitive adhesive layer of the present invention is suitable for optical applications.

The haze (according to JIS K7136) of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 1.0% or less, more preferably 0.8% or less. A haze of 1.0% or less is preferable because excellent transparency and appearance can be obtained. Although the lower limit of haze is not particularly limited, it is theoretically 0%, and practically may be more than 0.01%. Incidentally, the haze is, for example, an adhesive layer (thickness: 100 μm), which is allowed to stand in a normal state (23° C., 50% RH) for at least 24 hours, and then slide glass (for example, total light transmittance of 92%, Haze of 0.2%) can be used as a sample and measured using a haze meter (manufactured by Murakami Color Research Laboratory, trade name "HM-150N") or its equivalent.

The total light transmittance (according to JIS K7361-1) in the visible light wavelength region of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 90% or more, more preferably 91% or more, and still more preferably 92% or more. is. When the total light transmittance is 90% or more, excellent transparency and excellent appearance can be obtained, which is preferable. The upper limit of the total light transmittance is not particularly limited, but theoretically, it is a value excluding light loss (Fresnel loss) due to reflection occurring at the air interface from 100%, and in practice it may be 95% or less. . The above total light transmittance is measured, for example, by using an adhesive layer (thickness: 100 μm), leaving it at normal conditions (23° C., 50% RH) for at least 24 hours, and then removing it if it has a release liner. A haze meter (manufactured by Murakami Color Research Laboratory Co., Ltd., trade name "HM-150N") is used as a sample, which is peeled off and laminated on a slide glass (for example, a total light transmittance of 92% and a haze of 0.2%). ”) or its equivalent.

The method for producing the pressure-sensitive adhesive layer of the present invention is not particularly limited. For example, it can be produced by preparing the pressure-sensitive adhesive composition (precursor composition) of the present invention and, if necessary, performing irradiation with active energy rays, heat drying, and the like. Specifically, the hydrogenated polyolefin-based resin (B), other additives, etc. are added to a mixture of monomer components or a partial polymer thereof, as necessary, and the mixture is prepared by mixing. is mentioned.

The pressure-sensitive adhesive layer of the present invention is preferably formed from a pressure-sensitive adhesive composition containing an acrylic polymer (A) and a hydrogenated polyolefin resin (B).
Further, the pressure-sensitive adhesive layer of the present invention comprises a mixture of monomer components constituting the acrylic polymer (A) or a partial polymer of a mixture of monomer components constituting the acrylic polymer (A), and a hydrogenated polyolefin resin (B ) and is preferably formed by a pressure-sensitive adhesive composition containing.

The pressure-sensitive adhesive composition of the present invention may contain, in addition to the above, a polyfunctional (meth)acrylate, a silane coupling agent, and other additives described below.
In addition, in this specification, the above-mentioned "mixture of monomer components" includes the case of being composed of a single monomer component and the case of being composed of two or more monomer components. In addition, the above-mentioned "partially polymerized mixture of monomer components" means a composition in which one or more of the constituent monomer components of the above-mentioned "mixture of monomer components" is partially polymerized. do.

In this specification, for example, when "the pressure-sensitive adhesive layer of the present invention contains an acrylic polymer (A) and a hydrogenated polyolefin resin (B)", the pressure-sensitive adhesive layer forming the pressure-sensitive adhesive layer of the present invention A case where the agent composition (the pressure-sensitive adhesive composition of the present invention) contains an acrylic polymer (A) and a hydrogenated polyolefin resin (B) is also included. The same applies when the pressure-sensitive adhesive layer of the present invention contains components other than the acrylic polymer (A) and the hydrogenated polyolefin resin (B), does not contain them, or does not substantially contain them.

The pressure-sensitive adhesive composition of the present invention may have any form, for example, emulsion type, hot melt type (hot melt type), non-solvent type (active energy ray curable type, e.g., monomer mixture, or monomer mixtures and partially polymerized products thereof) and the like. In particular, the pressure-sensitive adhesive composition of the present invention is preferably non-solvent type. This is because when a pressure-sensitive adhesive layer is to be obtained using a solvent-based pressure-sensitive adhesive composition, defects in appearance such as citrus peel are likely to occur. In addition, "yuzu skin" refers to a phenomenon in which unevenness occurs like the skin of "yuzu", which is a kind of citrus fruit. Moreover, the pressure-sensitive adhesive composition of the present invention is preferably active energy ray-curable from the viewpoint of obtaining a pressure-sensitive adhesive layer with excellent appearance. In this specification, the pressure-sensitive adhesive composition means a composition used for forming the pressure-sensitive adhesive layer, and includes the meaning of the composition used for forming the pressure-sensitive adhesive.

As described above, the pressure-sensitive adhesive composition of the present invention is preferably non-solvent type, that is, it preferably contains no or substantially no organic solvent.
The organic solvent is not particularly limited as long as it is an organic compound used as a solvent. Examples include hydrocarbon solvents such as cyclohexane, hexane, and heptane; aromatic solvents such as toluene and xylene; ethyl acetate, methyl acetate, and the like. ketone solvents such as acetone and methyl ethyl ketone; and alcohol solvents such as methanol, ethanol, butanol and isopropyl alcohol. In addition, the mixed solvent containing 2 or more types of organic solvents may be sufficient as the said organic solvent.

In the pressure-sensitive adhesive composition of the present invention, “substantially free of organic solvent” means that the organic solvent is not actively blended, except when the organic solvent is unavoidably mixed. Specifically, the content of the organic solvent in the adhesive composition is 1.0% by weight or less (preferably 0.5% by weight or less, more preferably 0.2% by weight or less) can be said to be substantially free.

As the base polymer that constitutes the adhesive composition of the present invention, acrylic polymers are preferred because of their transparency, weather resistance, adhesion reliability, and the fact that functional design of the adhesive layer can be easily performed due to the wide variety of monomers. is preferably included. In other words, the pressure-sensitive adhesive composition of the present invention is preferably an acrylic pressure-sensitive adhesive composition containing the below-described acrylic polymer (A) as a base polymer. In addition, acrylic polymer (A) can be used individually or in combination of 2 or more types.

The content of the acrylic polymer (A) as the base polymer in the adhesive composition of the present invention is not particularly limited, but is preferably 74% by weight or more (for example, 74 to 99.9% by weight), and more It is preferably 80% by weight or more (for example, 80 to 99.9% by weight).

More preferably, the pressure-sensitive adhesive composition of the present invention does not contain, or substantially does not contain, a carboxyl group-containing monomer as a monomer component constituting the acrylic polymer (A). Therefore, the pressure-sensitive adhesive layer can obtain an effect of preventing corrosion of metal wiring such as metal mesh wiring and silver nanowires. The content of the carboxyl group-containing monomer is preferably 0.05% by weight or less (for example, 0 to 0.05% by weight), more preferably 0.01% by weight or less (for example, , 0 to 0.01% by weight), more preferably 0.001% by weight or less (for example, 0 to 0.001% by weight), is substantially not contained.

[1-1. Acrylic polymer (A)]
The pressure-sensitive adhesive composition of the present invention is preferably an acrylic pressure-sensitive adhesive composition containing acrylic polymer (A) as a main component. Although the specific content of the acrylic polymer (A) is not particularly limited, it is 74% by weight or more (for example, 74 to 99.9% by weight) relative to the total amount (total weight, 100% by weight) of the pressure-sensitive adhesive composition of the present invention. %), more preferably 80% by weight or more (for example, 80 to 99.9% by weight).

The pressure-sensitive adhesive composition of the present invention that forms the pressure-sensitive adhesive layer containing the acrylic polymer (A) as a main component is not particularly limited, but for example, a composition containing the acrylic polymer (A) as an essential component; Examples thereof include a mixture of monomer components constituting the system polymer (A) (sometimes referred to as a "monomer mixture") or a composition containing a partial polymer thereof as an essential component. Although not particularly limited, examples of the former include so-called water-dispersible compositions (emulsion-type compositions), and examples of the latter include so-called active energy ray-curable compositions. In addition, the said adhesive composition may contain the other additive agent as needed.

The above-mentioned "monomer mixture" includes cases where it is composed of a single monomer component and cases where it is composed of two or more monomer components. Moreover, the above-mentioned "partially polymerized product" means a composition in which one or more of the components of the monomer mixture are partially polymerized. Among them, the pressure-sensitive adhesive composition is preferably a composition containing a monomer mixture or a partial polymer thereof as an essential component.

The acrylic polymer (A) is a polymer (polymer) containing an acrylic monomer (acrylic monomer) as an essential monomer unit (monomer unit, monomer structural unit). In other words, the acrylic polymer (A) is a polymer containing structural units derived from acrylic monomers as structural units. In other words, the acrylic polymer (A) is a polymer constituted (formed) with an acrylic monomer as an essential monomer component. In this specification, "(meth)acryl" means either one or both of "acryl" and "methacryl", and the same applies to others. Although the weight average molecular weight of the acrylic polymer (A) is not particularly limited, it is preferably from 100,000 to 5,000,000.

The acrylic polymer (A) preferably contains a (meth)acrylic acid alkyl ester (A) (a (meth)acrylic acid alkyl ester having an alkyl group having 8 or more carbon atoms) as an essential monomer unit. That is, the acrylic polymer (A) of the present invention is obtained by polymerizing a monomer component containing a (meth)acrylic acid alkyl ester having a medium- to long-chain alkyl group such as the (meth)acrylic acid alkyl ester (A). It is preferably obtained by The acrylic polymer (A) can realize a highly flexible pressure-sensitive adhesive layer due to the action of the medium to long chain alkyl groups, and can be used as a film having metal wiring such as a metal mesh film and a silver nanowire film. Even in the case of lamination, it is preferable in that the stress with the metal wiring can be sufficiently relieved and display unevenness can be prevented.

Examples of the (meth)acrylic acid alkyl ester (A) include octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, and (meth)acrylic acid. isononyl acid, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, (meth)acrylic acid Carbon of alkyl groups such as pentadecyl, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, etc. Examples thereof include (meth)acrylic acid alkyl esters having 8 or more carbon atoms (preferably 8 to 24 carbon atoms). In addition, you may use the (meth)acrylic-acid alkyl ester (A) individually or in combination of 2 or more types.

As the (meth)acrylic acid alkyl ester (A), an acrylic acid alkyl ester is preferable to a methacrylic acid alkyl ester in that the polymerization time of the acrylic polymer (A) can be shortened and the productivity can be improved. In particular, when the acrylic polymer (A) of the present invention is cured by radiation polymerization, acrylic acid alkyl esters are suitable.

Among them, the (meth)acrylic acid alkyl ester (A) can realize a highly flexible pressure-sensitive adhesive layer, and when a film having metal wiring such as a metal mesh film or a silver nanowire film is laminated, Also, (meth)acrylic acid alkyl ester having a branched chain alkyl group having 8 or more carbon atoms can be contained in that the stress with metal wiring can be sufficiently relaxed and display unevenness can be prevented. It preferably contains a (meth)acrylic acid alkyl ester having a branched alkyl group having 8 or 9 carbon atoms, more preferably 2-ethylhexyl (meth)acrylate, particularly preferably acrylic acid 2 - ethylhexyl (2EHA). Although the number of carbon atoms in the side chain alkyl group of the branched alkyl group is not particularly limited, an alkyl group having 1 to 3 carbon atoms (eg, methyl group, ethyl group, n-propyl group, isopropyl group) is preferable. A "side chain alkyl group" is an alkyl group substituted on the side chain of the carbon chain with the longest carbon number.

The content (percentage) of the (meth)acrylic acid alkyl ester (A) in the total monomer units of the acrylic polymer (A) (the total amount of the monomer components constituting the acrylic polymer (A)) is not particularly limited. Even when films with metal wiring such as metal mesh films and silver nanowire films are laminated together, the stress with the metal wiring can be sufficiently relaxed, and display unevenness can be reduced. is preferably 30 to 95 parts by weight, more preferably 35 to 90 parts by weight, still more preferably 40 to 85 parts by weight.

(Meth)acrylic acid alkyl ester (A) is a (meth)acrylic acid alkyl ester having a branched alkyl group having 8 or 9 carbon atoms (hereinafter referred to as (meth)acrylic acid alkyl ester (A1 )), further, a (meth)acrylic acid alkyl ester having a branched alkyl group having 10 to 24 carbon atoms (hereinafter referred to as a (meth)acrylic acid alkyl ester ( A2)) is preferably included.

When the (meth)acrylic acid alkyl ester (A) contains the (meth)acrylic acid alkyl ester (A2) in addition to the (meth)acrylic acid alkyl ester (A1), a long-chain branched alkyl group The effect can reduce the dielectric constant of the pressure-sensitive adhesive layer of the present invention, and the pressure-sensitive adhesive layer can be applied even when applied on a transparent conductive film having a metal wiring layer such as metal mesh wiring and silver nanowires. has a low dielectric constant, which is preferable in that malfunction can be prevented.

The Tg of the homopolymer of (meth)acrylic acid alkyl ester (A2) is preferably -80 to 0°C, more preferably -70 to -10°C. If the Tg of the homopolymer is -80°C or less, the elastic modulus of the pressure-sensitive adhesive layer at room temperature may become too low, and if it exceeds 0°C, the adhesive strength may decrease. The Tg of a homopolymer is a value measured by a differential scanning calorimeter (DSC). In addition, the branched alkyl group having 10 to 24 carbon atoms has 10 to 24 carbon atoms because it can satisfy moderately low dielectric constant and elastic modulus. An alkyl (meth)acrylate having an appropriately preferred alkyl group can be selected. For example, when a (meth)acrylic polymer is produced by solution polymerization or the like, the alkyl group preferably has 10 to 18 carbon atoms, more preferably 10 to 16 carbon atoms, and more preferably 10 to 16 carbon atoms. 14 is preferred. When the acrylic polymer (A) is produced by radiation polymerization or the like, the alkyl group preferably has 12 to 18 carbon atoms, more preferably 14 to 18 carbon atoms.

The (meth)acrylic acid alkyl ester (A2) includes, for example, isodecyl acrylate (10 carbon atoms, homopolymer Tg = -60°C, hereinafter simply referred to as Tg), isodecyl methacrylate (10 carbon atoms, Tg = −41° C.), isomystyryl acrylate (14 carbon atoms, Tg=−56° C.), isostearyl acrylate (18 carbon atoms, Tg=−18° C.), 2-propylheptyl acrylate, isoundecyl acrylate, isododecyl acrylate, Isotridecyl acrylate, isopentadecyl acrylate, isohexadecyl acrylate, isoheptadecyl acrylate, and the above-exemplified methacrylate monomers can be exemplified. The (meth)acrylic acid alkyl ester (A2) may be used alone or in combination of two or more.

Among the branched-chain alkyl groups having 10 to 24 carbon atoms, those having a branched-chain alkyl group such as a t-butyl group at the end of an ester group particularly have an increased molar volume and are dipolar. It is preferable in that it is considered that the child moment is lowered and a pressure-sensitive adhesive layer having a balance of both can be obtained. It is also preferable in terms of excellent compatibility with the acrylic polymer (A) and the hydrogenated polyolefin resin (B) of the present invention. The branched-chain alkyl group at the end of the ester group is preferably a branched-chain alkyl group having 4 to 6 carbon atoms such as a t-butyl group, a neopentyl group, a t-pentyl group, and particularly a t-butyl group. preferable. Preferred examples of the (meth)acrylic acid alkyl ester (A2) having a t-butyl group at the end of the ester group include isostearyl acrylate represented by the following formula.

The content (percentage) of the (meth)acrylic acid alkyl ester (A1) in the total monomer units of the acrylic polymer (A) (the total amount of the monomer components constituting the acrylic polymer (A)) is not particularly limited. Even when films with metal wiring such as metal mesh films and silver nanowire films are laminated together, the stress with the metal wiring can be sufficiently relaxed, and display unevenness can be reduced. is preferably 30 parts by weight or more, more preferably 45 parts by weight or more, and still more preferably 50 parts by weight, relative to the total amount (100 parts by weight) of the monomer components constituting the acrylic polymer (A) in that it is possible to prevent parts or more, and may be 55 parts by weight or more. The content is preferably 70 parts by weight or less, more preferably 65 parts by weight or less, and even more preferably 60 parts by weight or less from the viewpoint of reducing the dielectric constant of the pressure-sensitive adhesive layer to prevent malfunction.

The content (ratio) of the (meth)acrylic acid alkyl ester (A2) in all the monomer units of the acrylic polymer (A) (100 parts by weight of the total amount of the monomer components constituting the acrylic polymer (A)) is not particularly limited. However, it is preferably 10 parts by weight or more, more preferably 15 parts by weight or more, and even more preferably 20 parts by weight or more, from the viewpoint of reducing the dielectric constant of the pressure-sensitive adhesive layer to prevent malfunction. In addition, the above content can realize a highly flexible adhesive layer, and even when a film having metal wiring such as a metal mesh film or a silver nanowire film is laminated, the stress with the metal wiring can be reduced. It is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, even more preferably 35 parts by weight or less, and particularly preferably 30 parts by weight or less, in terms of sufficient relaxation to prevent display unevenness.

(Meth)acrylic acid alkyl ester (A2) relative to the content of the (meth)acrylic acid alkyl ester (A1) in all monomer units of the acrylic polymer (A) (the total amount of the monomer components constituting the acrylic polymer (A)) The content ratio of ((meth)acrylic acid alkyl ester (A2) content / (meth)acrylic acid alkyl ester (A1) content) is not particularly limited, but realizes a highly flexible adhesive layer Even when a film having metal wiring such as a metal mesh film or a silver nanowire film is attached, the stress with the metal wiring can be sufficiently relaxed to prevent display unevenness. , is preferably 1.1 or less, more preferably 0.6 or less, still more preferably 0.55 or less, particularly preferably 0.5 or less, and may be 0.45 or less. again. The ratio is preferably 0.2 or more, more preferably 0.25 or more, still more preferably 0.3 or more, and 0.35 or more, from the viewpoint of reducing the dielectric constant of the pressure-sensitive adhesive layer to prevent malfunction. may be

The acrylic polymer (A) of the present invention is a (meth)acrylic acid alkyl ester other than the (meth)acrylic acid alkyl ester (A) (hereinafter sometimes referred to as "(meth)acrylic acid alkyl ester (B)" ) as a monomer component. Examples of the (meth)acrylic acid alkyl ester (B) include (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 1 to 7 carbon atoms. methyl acid, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate (n-butyl (meth) acrylate), isobutyl (meth) acrylate, (meth) ) s-butyl acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate and the like. The (meth)acrylic acid alkyl ester (B) may be used alone or in combination of two or more.

The content (percentage) of the (meth)acrylic acid alkyl ester (B) in the total monomer units of the acrylic polymer (A) (the total amount of the monomer components constituting the acrylic polymer (A)) is not particularly limited. Even when films with metal wiring such as metal mesh films and silver nanowire films are laminated together, the stress with the metal wiring can be sufficiently relaxed, and display unevenness can be reduced. is preferably 10 parts by weight or less, more preferably 5 parts by weight or less with respect to the total amount (100 parts by weight) of the monomer components constituting the acrylic polymer (A), in that it can prevent

In the acrylic polymer (A), in addition to the (meth)acrylic acid alkyl ester (A) and (meth)acrylic acid alkyl ester (B) as monomer units, copolymerizable monomers (copolymerizable monomers) may contain In other words, the acrylic polymer (A) may contain a copolymerizable monomer as a constituent monomer component. The copolymerizable monomers may be used alone or in combination of two or more.

Preferred copolymerizable monomers include hydroxyl group-containing monomers. When the acrylic polymer (A) contains a hydroxyl group-containing monomer as a monomer unit, it becomes easy to polymerize the constituent monomer components, and it becomes easy to obtain good cohesive strength. For this reason, it is easy to obtain strong adhesiveness, and by increasing the gel fraction, it is possible to realize a pressure-sensitive adhesive layer that does not easily deteriorate the appearance of a display device or an input device even under low pressure conditions. It becomes easy to obtain anti-foaming peeling property. Furthermore, it becomes easy to suppress whitening of the adhesive sheet that may occur in a high-humidity environment.

The content (proportion) of the hydroxyl group-containing monomer relative to the total amount (100 parts by weight) of the monomer components constituting the acrylic polymer (A) is not particularly limited. When the amount of the hydroxyl group-containing monomer is at least a certain amount, it becomes easier to obtain adhesion reliability such as adhesiveness and resistance to foaming and peeling in terms of cohesive force. The lower limit of the content of the hydroxyl group-containing monomer is preferably 0.1 part by weight or more, more preferably 1 part by weight or more, and still more preferably 3 parts by weight or more. Further, the upper limit of the content of the hydroxyl group-containing monomer is preferably 25 parts by weight or less, more preferably 20 parts by weight or less, from the viewpoint of easily obtaining compatibility with the hydrogenated polyolefin resin (B). More preferably, it is 15 parts by weight or less.

Furthermore, nitrogen atom-containing monomers are preferably used as the copolymerizable monomer. When the acrylic polymer (A) contains a nitrogen atom-containing monomer as a monomer unit, it becomes easy to obtain an appropriate cohesive force. For this reason, the 180° (degree) peeling adhesive force to the glass plate and the 180° peeling adhesive force to the acrylic plate are increased, making it easier to obtain strong adhesiveness, and increasing the gel fraction under low pressure conditions. It is possible to realize a pressure-sensitive adhesive layer that does not easily deteriorate the appearance of the display device or the input device even under the condition, and it is easy to obtain excellent anti-foaming/peeling property. Furthermore, when the pressure-sensitive adhesive layer makes it easier to obtain moderate flexibility, the 300% tensile residual stress is adjusted within a specific range, and films with metal wiring such as metal mesh films and silver nanowire films are laminated. Also, the stress with the metal wiring can be sufficiently relaxed to prevent display unevenness.

When the acrylic polymer (A) contains the nitrogen atom-containing monomer as a monomer component constituting the polymer, the nitrogen atom in all the monomer components (100 parts by weight) constituting the acrylic polymer (A) The proportion of the contained monomer is not particularly limited, but is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and still more preferably 5 parts by weight or more. A ratio of 1 part by weight or more is preferable from the viewpoint of facilitating obtaining good cohesive strength and facilitating obtaining adhesion reliability at high temperatures. Furthermore, suppression of cloudiness and durability in a high-humidity environment can be further improved, and higher adhesion reliability to metal mesh wiring and silver nanowire layers can be obtained, which is preferable. In addition, the upper limit of the ratio of the nitrogen atom-containing monomer is 30 parts by weight or less from the viewpoint of obtaining a pressure-sensitive adhesive layer having appropriate flexibility to prevent display unevenness and obtaining a pressure-sensitive adhesive layer with excellent transparency. It is preferably 25 parts by weight or less, and still more preferably 20 parts by weight or less.

The ratio of the hydroxyl group-containing monomer and the nitrogen atom-containing monomer contained in the acrylic polymer (A) (hydroxyl group-containing monomer/nitrogen atom-containing monomer) is not particularly limited, and is, for example, 95/5 to 5/95, preferably 90/10. 10/90, more preferably 70/30 to 30/70, more preferably 60/40 to 40/60, particularly preferably 50/50 to 35/65.

Furthermore, as the copolymerizable monomer, an alicyclic structure-containing monomer is preferably used. When the acrylic polymer (A) contains a nitrogen atom-containing monomer as a monomer unit, it becomes easy to obtain an appropriate cohesive force. For this reason, the 180° (degree) peeling adhesive force to the glass plate and the 180° peeling adhesive force to the acrylic plate are increased, making it easier to obtain strong adhesiveness, and increasing the gel fraction under low pressure conditions. It is possible to realize a pressure-sensitive adhesive layer that does not easily deteriorate the appearance of the display device or the input device even under the condition, and it is easy to obtain excellent anti-foaming/peeling property. Furthermore, when the pressure-sensitive adhesive layer makes it easier to obtain moderate flexibility, the 300% tensile residual stress is adjusted within a specific range, and films with metal wiring such as metal mesh films and silver nanowire films are laminated. Also, the stress with the metal wiring can be sufficiently relaxed to prevent display unevenness.

When the acrylic polymer (A) contains the alicyclic structure-containing monomer as a monomer component constituting the polymer, the lipid in all the monomer components (100 parts by weight) constituting the acrylic polymer (A) The ratio of the ring structure-containing monomer is not particularly limited, but is preferably 3 parts by weight or more, and 10 parts by weight or more, from the viewpoint of improving durability, metal mesh wiring, and obtaining higher adhesion reliability to the silver nanowire layer. is more preferable. The upper limit of the ratio of the alicyclic structure-containing monomer is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, from the viewpoint of obtaining a pressure-sensitive adhesive layer having appropriate flexibility and preventing display unevenness. More preferably, it is 30 parts by weight or less.

The above acrylic polymer (A) can be obtained by polymerizing the above monomer units (monomer components) by a known or commonly used polymerization method. Examples of the polymerization method of the acrylic polymer (A) include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a polymerization method by active energy ray irradiation (active energy ray polymerization method). Among them, the solution polymerization method and the active energy ray polymerization method are preferable, and the active energy ray polymerization method is more preferable, from the viewpoints of the transparency, water resistance, cost, etc. of the pressure-sensitive adhesive layer.

Examples of the active energy ray irradiated during the active energy ray polymerization (photopolymerization) include ionizing radiation such as α-ray, β-ray, γ-ray, neutron beam, and electron beam, and ultraviolet rays, particularly ultraviolet rays. is preferred. Moreover, the irradiation energy, irradiation time, irradiation method, and the like of the active energy ray are not particularly limited as long as the photopolymerization initiator can be activated to cause the reaction of the monomer components.

Various general solvents may be used in the polymerization of the acrylic polymer (A). Examples of such solvents include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; Alicyclic hydrocarbons such as cyclohexane; and organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. In addition, a solvent may be used individually or in combination of 2 or more types.

Further, in the polymerization of the acrylic polymer (A), a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator (photoinitiator) may be used depending on the type of polymerization reaction. In addition, a polymerization initiator may be used individually or in combination of 2 or more types.

The photopolymerization initiator is not particularly limited. Active oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and the like can be mentioned. In addition, a photoinitiator may be used individually or in combination of 2 or more types.

Examples of the benzoin ether-based photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, anisole methyl ether and the like. Examples of the acetophenone-based photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenylketone, 4-phenoxydichloroacetophenone, 4-(t-butyl ) and dichloroacetophenone. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one, and the like. be done. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime-based photopolymerization initiator include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. Examples of the benzoin-based photopolymerization initiator include benzoin. Examples of the benzyl-based photopolymerization initiator include benzyl. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenyl ketone, and the like. Examples of the ketal-based photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

The amount of the photopolymerization initiator to be used is not particularly limited. 001 to 1 part by weight, more preferably 0.01 to 0.50 part by weight.

Further, the thermal polymerization initiator is not particularly limited, but for example, an azo polymerization initiator, a peroxide polymerization initiator (e.g., dibenzoyl peroxide, tert-butyl permaleate, etc.), a redox polymerization initiator agents and the like. Among them, the azo polymerization initiator disclosed in JP-A-2002-69411 is preferable. Examples of the azo polymerization initiator include 2,2'-azobisisobutyronitrile (hereinafter sometimes referred to as "AIBN"), 2,2'-azobis-2-methylbutyronitrile (hereinafter, " AMBN”), 2,2′-azobis(2-methylpropionate)dimethyl, 4,4′-azobis-4-cyanovaleric acid and the like.

The amount of the thermal polymerization initiator used is not particularly limited. For example, in the case of the azo polymerization initiator, all monomer units of the acrylic polymer (A) (the total amount of monomer components constituting the acrylic polymer (A)) It is preferably 0.05 to 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight, per 100 parts by weight.

[1-2. Carboxyl group-containing monomer, etc.]
The adhesive composition of the present invention preferably does not substantially contain a carboxyl group-containing monomer as a monomer component constituting the acrylic polymer (A). The phrase "substantially does not contain" means that it is not actively blended except when it is unavoidably mixed. A carboxyl group-containing monomer means a monomer having at least one carboxyl group in the molecule. From the viewpoint of obtaining a more excellent anti-corrosion effect, specifically, the content of the carboxyl group-containing monomer is 0.00% relative to the total amount (100 parts by weight) of the monomer components constituting the acrylic polymer (A). 05 parts by weight or less (e.g., 0 to 0.05 parts by weight), more preferably 0.01 parts by weight or less (e.g., 0 to 0.01 parts by weight), still more preferably 0.001 parts by weight or less (e.g., , 0 to 0.001 parts by weight) can be said to be substantially free. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Acid anhydride group-containing monomers such as maleic acid and itaconic anhydride are also intended to be included.

Furthermore, from the viewpoint of obtaining a more excellent anti-corrosion effect, the pressure-sensitive adhesive composition of the present invention contains substantially no carboxyl group-containing monomer as a monomer component constituting the acrylic polymer (A). Also, monomers having acidic groups (sulfo group, phosphoric acid group, etc.) other than carboxyl groups are preferably not substantially contained as monomer components constituting the acrylic polymer (A). That is, the acrylic polymer (A) preferably contains substantially no carboxyl group-containing monomers and other monomers having acidic groups as constituent monomer components. Specifically, the total amount of the carboxyl group-containing monomers and other monomers having an acidic group as the monomer components constituting the acrylic polymer (A) is the total amount of the monomer components constituting the acrylic polymer (A) (100 parts by weight ), preferably 0.05 parts by weight or less (e.g., 0 to 0.05 parts by weight), more preferably 0.01 parts by weight or less (e.g., 0 to 0.01 parts by weight), more preferably 0 It can be said that the content of 0.001 part by weight or less (for example, 0 to 0.001 part by weight) is substantially absent.

From the same viewpoint, the pressure-sensitive adhesive composition of the present invention preferably does not contain or substantially does not contain an acidic group-containing monomer as a monomer component constituting a polymer other than the acrylic polymer (A). For example, it is preferred that substantially no carboxyl group-containing monomer is contained. The meaning of "not containing substantially", the preferred degree, and the monomer having an acidic group other than a carboxyl group are the same as in the case of the monomer component constituting the acrylic polymer (A). .

[1-3. Basic group-containing monomer]
In addition, it is preferable that the pressure-sensitive adhesive composition of the present invention does not contain or substantially does not contain a basic group-containing monomer as a monomer component constituting the acrylic polymer (A). In addition, it is preferable that the monomer component constituting the polymer other than the acrylic polymer (A) does not substantially contain a basic group-containing monomer. It is the same as in the case of the carboxyl group-containing monomer that the agent layer preferably contains substantially no basic group-containing monomer. In addition, the same applies to the meaning of "substantially free of", the preferred degree, and the like.

[1-4. Hydroxyl Group-Containing Monomer]
A hydroxyl group-containing monomer means a monomer having at least one hydroxyl group in the molecule. Also, a monomer having at least one hydroxyl group in the molecule and at least one carboxyl group in the molecule is a carboxyl group-containing monomer and is not a hydroxyl group-containing monomer. The hydroxyl group-containing monomer is not particularly limited, but specific examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, ( 3-hydroxypropyl meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, (meth)acrylic acid hydroxyl group-containing (meth)acrylic acid esters such as hydroxyllauryl and (meth)acrylic acid (4-hydroxymethylcyclohexyl); vinyl alcohol, allyl alcohol and the like. Among them, the hydroxyl group-containing monomer is preferably a hydroxyl group-containing (meth)acrylic acid ester, more preferably acrylic acid 2, from the viewpoint that it becomes easy to obtain good cohesive force and it becomes easy to obtain adhesion reliability at high temperatures. - hydroxyethyl (HEA), 2-hydroxypropyl (meth)acrylate (HPA), 4-hydroxybutyl acrylate (4HBA). Incidentally, the hydroxyl group-containing monomers may be used alone or in combination of two or more.

[1-5. Nitrogen Atom-Containing Monomer]
A nitrogen atom-containing monomer means a monomer having at least one nitrogen atom in its molecule (in one molecule). However, the hydroxyl group-containing monomer does not include the nitrogen atom-containing monomer. That is, in this specification, a monomer having a hydroxyl group and a nitrogen atom in its molecule is included in the nitrogen atom-containing monomer. Also, a monomer having at least one nitrogen atom in the molecule and at least one carboxyl group in the molecule is a carboxyl group-containing monomer and is not a nitrogen atom-containing monomer.

As the nitrogen atom-containing monomer, N-vinyl cyclic amides, (meth)acrylamides, and the like are preferable from the viewpoint of improving resistance to foaming and peeling. Incidentally, the nitrogen atom-containing monomers may be used alone or in combination of two or more.

（式（１）中、Ｒ¹は２価の有機基を示す） As the N-vinyl cyclic amide, an N-vinyl cyclic amide represented by the following formula (1) is preferable from the viewpoint of easily obtaining good cohesive strength and easily obtaining adhesion reliability at high temperatures.

(In formula (1), R ¹ represents a divalent organic group)

R ¹ in the above formula (1) is a divalent organic group, preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, more preferably a divalent saturated hydrocarbon group (e.g., carbon number 3 to 5 alkylene groups, etc.).

As the N-vinyl cyclic amide represented by the above formula (1), N-vinyl-2-pyrrolidone (NVP), N-vinyl-2-piperidone, N-vinyl -2-caprolactam, N-vinyl-3-morpholinone, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione and the like are preferred, more preferably N-vinyl-2- pyrrolidone, N-vinyl-2-caprolactam, more preferably N-vinyl-2-pyrrolidone.

Examples of the (meth)acrylamides include (meth)acrylamide, N-alkyl(meth)acrylamide, N,N-dialkyl(meth)acrylamide and the like. Examples of the N-alkyl(meth)acrylamide include N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, Nn-butyl(meth)acrylamide, N-octylacrylamide and the like. Furthermore, the above N-alkyl(meth)acrylamides also include (meth)acrylamides having an amino group such as dimethylaminoethyl(meth)acrylamide, diethylaminoethyl(meth)acrylamide, and dimethylaminopropyl(meth)acrylamide. Examples of the N,N-dialkyl(meth)acrylamides include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl (Meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(t-butyl)(meth)acrylamide and the like.

The (meth)acrylamides also include, for example, various N-hydroxyalkyl(meth)acrylamides. Examples of the N-hydroxyalkyl(meth)acrylamide include N-methylol(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N- (1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, N-methyl-N-2-hydroxyethyl(meth)acrylamide and the like.

The (meth)acrylamides also include, for example, various N-alkoxyalkyl(meth)acrylamides. Examples of the N-alkoxyalkyl(meth)acrylamides include N-methoxymethyl(meth)acrylamide and N-butoxymethyl(meth)acrylamide.

Nitrogen atom-containing monomers other than the N-vinyl cyclic amides and the (meth)acrylamides include, for example, aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, dimethylamino (meth)acrylate propyl, amino group-containing monomers such as t-butylaminoethyl (meth)acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; (meth)acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinyl imidazole, N-vinylpyrazine, N-vinylmorpholine, N-vinylpyrazole, vinylpyridine, vinylpyrimidine, vinyloxazole, vinylisoxazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth)acryloylpyrrolidone, (meth)acryloyl heterocyclic ring-containing monomers such as pyrrolidine, (meth)acryloylpiperidine and N-methylvinylpyrrolidone; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide and N-phenylmaleimide, N-methylitaconimide , N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-laurylitaconimide, N-cyclohexylitaconimide and other itaconimide monomers, N-(meth)acryloyl imide group-containing monomers such as succinimide monomers such as oxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide; 2-(meth)acryloyloxy Examples thereof include isocyanate group-containing monomers such as ethyl isocyanate.

[1-6. Alicyclic Structure-Containing Monomer]
The alicyclic structure-containing monomer means a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group and having an alicyclic structure. For example, a (meth)acrylic acid alkyl ester having a cycloalkyl group is included in the alicyclic structure-containing monomer. However, a monomer having at least one alicyclic structure in the molecule and at least one carboxyl group in the molecule is a carboxyl group-containing monomer, and is not an alicyclic structure-containing monomer. In addition, an alicyclic structure containing monomer can be used individually or in combination of 2 or more types.

The alicyclic structure in the alicyclic structure-containing monomer is a cyclic hydrocarbon structure, preferably having 5 or more carbon atoms, more preferably 6 to 24 carbon atoms, further preferably 6 to 15 carbon atoms, and 6 to 10 are particularly preferred.

Examples of the alicyclic structure-containing monomer include cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, cyclo Heptyl (meth) acrylate, cyclooctyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, HPMPA represented by the following formula (2), TMA represented by the following formula (3)- 2. (Meth)acrylic monomers such as HCPA represented by the following formula (4). In the following formula (4), there is no particular limitation on the bonding position between the cyclohexyl ring connected by a line and the structural formula in parentheses. Among these, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, and 3,3,5-trimethylcyclohexyl (meth)acrylate are preferred.

[1-7. Other copolymerizable monomers]
Examples of copolymerizable monomers in the acrylic polymer (A) include, in addition to the above nitrogen atom-containing monomers, hydroxyl group-containing monomers, and alicyclic structure-containing monomers, (meth)acrylic acid alkoxyalkyl esters [e.g., (meth) 2-methoxyethyl acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, (meth)acrylate 4-methoxybutyl acrylate, 4-ethoxybutyl (meth)acrylate, etc.]; epoxy group-containing monomers [e.g., glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, etc.]; sulfonic acid group-containing monomers [e.g. , sodium vinyl sulfonate, etc.]; phosphoric acid group-containing monomer; benzyl etc.]; vinyl esters [e.g. vinyl acetate, vinyl propionate etc.]; aromatic vinyl compounds [e.g. styrene, vinyltoluene etc.]; olefins or dienes [e.g. ethylene, propylene, butadiene, isoprene, isobutylene etc.]; vinyl ethers [eg, vinyl alkyl ether etc.]; vinyl chloride and the like.

[1-8. Hydrogenated polyolefin resin (B)]
The pressure-sensitive adhesive composition of the present invention is preferably an acrylic pressure-sensitive adhesive composition containing an acrylic polymer (A) as a main component and a hydrogenated polyolefin resin (B). The pressure-sensitive adhesive composition of the present invention, in addition to the acrylic polymer (A), contains the hydrogenated polyolefin resin (B), from the viewpoint that the appearance of the display device and the input device is less likely to deteriorate under low pressure conditions. and preferred. In addition, the hydrogenated polyolefin resin (B) is a material with a low dielectric constant. It is possible to realize a highly flexible adhesive layer without the need to reduce the molecular weight. is sufficiently alleviated to prevent display unevenness. In addition, the hydrogenated polyolefin resin (B) is also excellent in compatibility with the acrylic polymer (A), and is therefore preferable in that the transparency of the pressure-sensitive adhesive composition of the present invention can be maintained at a higher level. Hydrogenated polyolefin resin (B) can be used individually or in combination of 2 or more types.

The hydrogenated polyolefin resin (B) can realize a highly flexible adhesive layer, and even when a film having metal wiring such as a metal mesh film or a silver nanowire film is laminated, it can be From the point of view of being able to sufficiently relax the stress of , and prevent display unevenness, it is preferable to exhibit liquid fluidity at 25°C. The fact that the hydrogenated polyolefin resin (B) exhibits liquid fluidity at 25°C means that the viscosity measured at 25°C by a Brookfield viscometer is 10,000 mPa·s or less.

The hydrogenated polyolefin resin (B) is obtained by reducing the carbon-carbon double bonds contained in the polyolefin resin by a hydrogenation reaction. Since the hydrogenated polyolefin resin (B) has reduced carbon-carbon double bonds in the molecule, for example, when the pressure-sensitive adhesive composition of the present invention is cured by ultraviolet irradiation, polymerization inhibition is unlikely to occur, and polymerization Since it is difficult for the rate to decrease and the molecular weight to decrease, the adhesion reliability at high temperatures of the pressure-sensitive adhesive composition of the present invention can be maintained at a high level.

The hydrogenation rate of the hydrogenated polyolefin resin (B) is preferably 90% or more, more preferably 95% or more, and still more preferably 97% or more, from the viewpoint of preventing polymerization inhibition and ensuring adhesion reliability at high temperatures. is. Although the upper limit of the hydrogenation rate is not particularly limited, it is theoretically 100%, and practically it may be 99.9% or less or 99.8% or less. The hydrogenation rate of the hydrogenated polyolefin resin (B) can be determined by quantifying the amount of double bonds remaining in the hydrogenated polyolefin resin (B) by ¹ H-NMR measurement.

The iodine value (Ig/100 g) of the hydrogenated polyolefin resin (B) is preferably 30 or less, more preferably 25 or less, and still more preferably 20 from the viewpoint of preventing polymerization inhibition and ensuring adhesion reliability at high temperatures. It is below. Although the lower limit of the iodine value is not particularly limited, it may be 0.1 or more or 0.2 or more. The iodine value is a value measured according to JIS K 0070-1992.

The number average molecular weight (Mn) of the hydrogenated polyolefin resin (B) imparts appropriate stress relaxation properties and fluidity to the pressure-sensitive adhesive layer and improves compatibility with the acrylic polymer (A). 1000 to 5000 are preferred. The number-average molecular weight (Mn) is preferably 1,000 or more, more preferably 1,500 or more, and still more preferably 1,800 or more in terms of imparting appropriate stress relaxation properties and fluidity to the pressure-sensitive adhesive composition. The number average molecular weight (Mn) is preferably 5000 or less, more It is preferably 4800 or less, more preferably 4600 or less.

The polydispersity (Mw/Mn) of the hydrogenated polyolefin resin (B) imparts appropriate stress relaxation and fluidity to the pressure-sensitive adhesive layer, improves compatibility with the acrylic polymer (A), It is preferably 2.0 or less, more preferably 1.8 or less, in terms of maintaining good transparency and suppressing haze. Although the lower limit of polydispersity is not particularly limited, it may be 1.0 or 1.1 or more in practice.

The number average molecular weight (Mn) and polydispersity (Mw/Mn) of the hydrogenated polyolefin resin (B) are values measured by gel permeation chromatography (GPC) and obtained based on polystyrene standards.

The hydrogenated polyolefin resin (B) contains hydrogenated polyolefin. The pressure-sensitive adhesive composition of the present invention contains a hydrogenated polyolefin as the hydrogenated polyolefin-based resin (B), thereby realizing a pressure-sensitive adhesive layer that does not easily deteriorate the appearance of display devices and input devices even under low pressure conditions. It is preferable in that it is possible.

The hydrogenated polyolefin is a hydrogenated polymer (polyolefin) having structural units derived from olefin. Hydrogenated polyolefins include α-olefins such as ethylene, propylene, 1-butene, isobutene and 1-hexene; diene compounds such as butadiene and isoprene; homopolymers and copolymers such as aromatic vinyl compounds such as styrene. Contains hydrogenated products. Hydrogenated polyolefins are preferably hydrogenated homopolymers or copolymers of diene compounds, such as hydrogenated polybutadiene and hydrogenated polyisoprene. Hydrogenated polyolefin can be used individually or in combination of 2 or more types.

Hydrogenated polyolefin resin (B) can realize a pressure-sensitive adhesive layer that does not easily deteriorate the appearance of display devices and input devices even under low pressure conditions. is preferably included.

The hydrogenated polyolefin polyol is a compound obtained by modifying the terminal of the hydrogenated polyolefin with a hydroxyl group. Hydrogenated polyolefin polyols are preferably hydroxyl group-modified products of hydrogenated homopolymers or copolymers of diene compounds, such as hydrogenated polybutadiene polyols and hydrogenated polyisoprene polyols. Hydrogenated polyolefin polyol can be used individually or in combination of 2 or more types.

The above-mentioned hydrogenated polyolefin and hydrogenated polyolefin polyol have the viewpoint that the appearance of the display device and the input device does not easily deteriorate under low pressure conditions, imparts appropriate stress relaxation and fluidity to the pressure-sensitive adhesive layer, and is an acrylic polyolefin. Hydrogenated polybutadiene polyol and hydrogenated polybutadiene polyol are preferable from the viewpoint of improving compatibility with the polymer (A).

上記式中、ｍは、水添ポリブタジエンの重合度を示す。 The hydrogenated polybutadiene is preferably represented by the following formula (5), and the hydrogenated polybutadiene polyol is preferably represented by the following formula (6).

In the above formula, m indicates the degree of polymerization of hydrogenated polybutadiene.

Commercially available products can be used as the hydrogenated polyolefin and the hydrogenated polyolefin polyol. Commercially available hydrogenated polyolefins include trade names "BI-2000" and "BI-3000" (manufactured by Nippon Soda Co., Ltd.). Commercially available hydrogenated polyolefin polyols include trade names “GI-1000”, “GI-2000” and “GI-3000” (manufactured by Nippon Soda Co., Ltd.), trade name “EPOL” (Idemitsu Kosan Co., Ltd.). ) made) and the like.

The content of the hydrogenated polyolefin resin (B) in the pressure-sensitive adhesive composition is not particularly limited, but from the viewpoint that the appearance of the display device or the input device is unlikely to deteriorate under low pressure conditions, the acrylic polymer (A ) to 100 parts by weight, preferably 1 part by weight or more, more preferably 3 parts by weight or more, still more preferably 5 parts by weight or more, and may be 8 parts by weight or more. On the other hand, from the viewpoint of suppressing the increase in haze, ensuring higher transparency, and maintaining high adhesive strength and adhesion reliability at high temperatures, the content of the hydrogenated polyolefin resin (B) is , preferably 35 parts by weight or less, more preferably 30 parts by weight or less, and even more preferably 25 parts by weight or less.

The content of the hydrogenated polyolefin in the pressure-sensitive adhesive composition is not particularly limited. On the other hand, it is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, still more preferably 1.5 parts by weight or more, and particularly preferably 2 parts by weight or more. On the other hand, from the viewpoint of suppressing the increase in haze, ensuring higher transparency, and maintaining high adhesive strength and adhesion reliability at high temperatures, the content of hydrogenated polyolefin is 20 parts by weight or less. is preferably 15 parts by weight or less, more preferably 12 parts by weight or less, and may be 10 parts by weight or less, or 5 parts by weight or less.

The content of the hydrogenated polyolefin polyol in the pressure-sensitive adhesive composition is not particularly limited, but from the viewpoint that the appearance of the display device or the input device is unlikely to deteriorate under low pressure conditions, 100 parts by weight of the acrylic polymer (A) is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, still more preferably 3 parts by weight or more, and may be 5 parts by weight or more, or 10 parts by weight or more. On the other hand, from the viewpoint of suppressing the increase in haze, ensuring higher transparency, and maintaining high adhesive strength and adhesion reliability at high temperatures, the content of the hydrogenated polyolefin polyol is 30 parts by weight. The following is preferable, more preferably 25 parts by weight or less, still more preferably 20 parts by weight or less, and particularly preferably 15 parts by weight or less.

The ratio of the hydrogenated polyolefin content to the hydrogenated polyolefin polyol content (hydrogenated polyolefin/hydrogenated polyolefin polyol) in the pressure-sensitive adhesive composition is not particularly limited. From the viewpoint that appearance is less likely to deteriorate, it is preferably 5/95 or more, more preferably 12/88 or more, and may be 15/85 or more, or 18/88 or more. In addition, from the viewpoint of suppressing the increase in haze and ensuring higher transparency, the appearance of the display device and the input device is less likely to deteriorate under low pressure conditions, and the transparency is ensured, the above ratio is It is preferably 90/10 or less, more preferably 80/20 or less, even more preferably 70/30 or less, and may be 55/45 or less, 45/55 or less, or 30/70 or less.

[1-9. Polyfunctional (meth)acrylate]
The pressure-sensitive adhesive composition of the present invention preferably further contains a polyfunctional (meth)acrylate. The polyfunctional (meth)acrylate acts as a cross-linking component, the pressure-sensitive adhesive composition has an appropriate cohesive force, and the appearance of display devices and input devices is less likely to deteriorate under low-pressure conditions.

Examples of polyfunctional (meth)acrylates include hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neo Pentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate , allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, and the like. In addition, polyfunctional (meth)acrylate may be used individually or in combination of 2 or more types.

The content (ratio) of the polyfunctional (meth)acrylate is not particularly limited, but the pressure-sensitive adhesive layer has an appropriate cohesive force, and even under low pressure conditions, the appearance of the display device or input device does not easily deteriorate. 0.001 parts by weight or more, more preferably 0.002 parts by weight or more, and still more preferably 0.005 parts by weight or more with respect to 100 parts by weight of the acrylic polymer (A) in terms of realizing an agent layer. Yes, and may be 0.01 parts by weight or more. In addition, the content (percentage) of the polyfunctional (meth)acrylate can realize a highly flexible pressure-sensitive adhesive layer, sufficiently relax the stress with the metal wiring, and prevent display unevenness. point, it is preferably 0.5 parts by weight or less, more preferably 0.35 parts by weight or less, still more preferably 0.2 parts by weight or less with respect to 100 parts by weight of the acrylic polymer (A), and 0.1 It may be less than or equal to parts by weight.

[1-10. Silane coupling agent]
The pressure-sensitive adhesive composition of the present invention preferably further contains a silane coupling agent. When the pressure-sensitive adhesive composition contains a silane coupling agent, it is preferable because excellent adhesion to glass (especially, excellent adhesion reliability to glass at high temperature and high humidity) can be easily obtained.

Examples of the silane coupling agent include, but are not limited to, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-aminopropyltrimethoxysilane. etc. Among them, γ-glycidoxypropyltrimethoxysilane is preferred. Furthermore, examples of the silane coupling agent include commercially available products such as the product name "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.). In addition, a silane coupling agent may be used individually or in combination of 2 or more types.

The content of the silane coupling agent is not particularly limited, but from the viewpoint of improving the adhesion reliability to glass, it is preferably 0.01 to 1 part by weight with respect to 100 parts by weight of the acrylic polymer (A), and more preferably. is 0.03 to 0.5 parts by weight.

[1-11. Crosslinking agent]
As described above, the pressure-sensitive adhesive composition of the present invention is preferably not solvent-based, that is, preferably contains no or substantially no cross-linking agent.
Examples of the cross-linking agent include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, melamine-based cross-linking agents, peroxide-based cross-linking agents, urea-based cross-linking agents, metal alkoxide-based cross-linking agents, metal chelate-based cross-linking agents, metal Examples include salt-based cross-linking agents, carbodiimide-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, and amine-based cross-linking agents. In particular, the pressure-sensitive adhesive composition of the present invention preferably does not contain or substantially does not contain an isocyanate-based cross-linking agent and/or an epoxy-based cross-linking agent as a cross-linking agent. preferably not.

Examples of the isocyanate-based crosslinking agent (polyfunctional isocyanate compound) include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; cyclopentylene diisocyanate; , cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate and other alicyclic polyisocyanates; 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate , xylylene diisocyanate and other aromatic polyisocyanates. Examples of the isocyanate-based cross-linking agent include trimethylolpropane/tolylene diisocyanate adduct [manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L"], trimethylolpropane/hexamethylene diisocyanate adduct [Nippon Polyurethane Kogyo Co., Ltd., trade name “Coronate HL”], trimethylolpropane/xylylene diisocyanate adduct [Mitsui Chemicals Co., Ltd., trade name “Takenate D-110N”].

Examples of the epoxy-based cross-linking agent (polyfunctional epoxy compound) include N,N,N',N'-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidyl aminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether , glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipate diglycidyl ester, o-phthalate diglycidyl ester, triglycidyl-tris(2 -hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. Examples of the epoxy-based cross-linking agent include commercially available products such as those manufactured by Mitsubishi Gas Chemical Company, Inc. under the trade name of "Tetrad C".

In the pressure-sensitive adhesive composition of the present invention, "substantially free of" a cross-linking agent means that the cross-linking agent is not actively blended except when the cross-linking agent is unavoidably mixed. Specifically, the content of the cross-linking agent in the adhesive composition is 1.0% by weight or less (preferably 0.5% by weight or less, more preferably 0.2% by weight or less) can be said to be substantially free. In addition, it is preferably 0.05 parts by weight or less (for example, 0 to 0.05 parts by weight), more preferably 0.01 parts by weight, based on the total amount (100 parts by weight) of the monomer components constituting the acrylic polymer (A). It can be said that the content of 0.001 part by weight or less (eg, 0 to 0.001 part by weight) is substantially not contained.

[1-12. Additive]
The pressure-sensitive adhesive composition of the present invention may optionally contain a cross-linking accelerator, a tackifying resin (rosin derivative, polyterpene resin, oil-soluble phenol, etc.), an anti-aging agent, a filler, a coloring agent (pigment, dye, etc.). , ultraviolet absorbers, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, rust inhibitors, antioxidants, etc. may From the viewpoint of suppressing an increase in haze of the pressure-sensitive adhesive layer of the present invention, it is preferable that the pressure-sensitive adhesive composition of the present invention substantially does not contain an antirust agent and an antioxidant. In addition, such an additive may be used individually or in combination of 2 or more types.

From the viewpoint of suppressing an increase in haze of the pressure-sensitive adhesive layer of the present invention, it is preferable that the pressure-sensitive adhesive composition of the present invention substantially does not contain an antirust agent and an antioxidant. “Substantially free of rust inhibitors and antioxidants” means that rust inhibitors and antioxidants are not actively blended, except when rust inhibitors and antioxidants are unavoidably mixed. Say things. Specifically, the content of the rust inhibitor and/or antioxidant in the adhesive composition is 1.0% by weight or less (preferably is 0.5% by weight or less, more preferably 0.2% by weight or less) can be said to be substantially free. Further, for example, 0.5 parts by weight or less (for example, 0 to 0.5 parts by weight), 0.05 parts by weight or less (for example, , 0 to 0.05 parts by weight), more preferably 0.01 parts by weight or less (e.g., 0 to 0.01 parts by weight), still more preferably 0.001 parts by weight or less (e.g., 0 to 0.001 parts by weight). parts by weight) can be said to be substantially free.

[1-13. Preparation of adhesive composition]
The pressure-sensitive adhesive composition of the present invention is prepared by mixing an acrylic polymer (A), a hydrogenated polyolefin resin (B), and optionally a polyfunctional (meth)acrylate, a silane coupling agent, and other additives, It can be prepared by stirring uniformly. At that time, from the viewpoint of uniform preparation, a monomer component constituting the acrylic polymer (A) may be blended as a diluent. For example, the hydrogenated polyolefin resin (B) may be diluted with a monomer component and added. When the monomer component constituting the acrylic polymer (A) is used as a diluent, in order to maintain the above properties of the pressure-sensitive adhesive layer, the acrylic polymer (A) is diluted with a monomer mixture excluding the monomer component used as the diluent. preferably prepared. The monomer component used as the diluent is not particularly limited, but for example, (meth)acrylic acid alkyl ester (A1) ((meth)acrylic acid alkyl ester having a branched alkyl group having 8 or 9 carbon atoms) is preferred. The amount of the monomer component used as the diluent is not particularly limited, and may be appropriately set so that the pressure-sensitive adhesive composition can be uniformly mixed.

[2. Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention is not particularly limited as long as it has the pressure-sensitive adhesive layer of the present invention (the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention).

The pressure-sensitive adhesive sheet of the present invention may be a double-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive layer surfaces on both sides, or may be a single-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive layer surfaces on only one side. Among them, a double-sided pressure-sensitive adhesive sheet is preferable from the viewpoint of bonding two members together. In this specification, the term "adhesive sheet" includes a tape-like one, that is, "adhesive tape". Moreover, in this specification, the adhesive layer surface may be called an "adhesive surface."

The pressure-sensitive adhesive sheet of the present invention may be provided with a release liner on the pressure-sensitive adhesive surface until use.

The pressure-sensitive adhesive sheet of the present invention may be a so-called "base-less type" pressure-sensitive adhesive sheet (hereinafter sometimes referred to as "base-less pressure-sensitive adhesive sheet") that does not have a base material (base layer). , a pressure-sensitive adhesive sheet having a substrate (hereinafter sometimes referred to as a "substrate-attached pressure-sensitive adhesive sheet"). Examples of the substrate-less pressure-sensitive adhesive sheet include, for example, a double-sided pressure-sensitive adhesive sheet consisting only of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer and a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer (sometimes referred to as "another pressure-sensitive adhesive layer"). ) and the like. On the other hand, the pressure-sensitive adhesive sheet with a substrate includes a pressure-sensitive adhesive sheet having the above pressure-sensitive adhesive layer on at least one side of a substrate. Among them, a substrate-less pressure-sensitive adhesive sheet (substrate-less double-sided pressure-sensitive adhesive sheet) is preferable, and a substrate-less double-sided pressure-sensitive adhesive sheet comprising only the above pressure-sensitive adhesive layer is more preferable. The above-mentioned "base material (base material layer)" does not include a release liner that is peeled off when the adhesive sheet is used (attached).

[2-1. Other physical properties of the adhesive sheet]
180° peeling adhesive strength at a tensile speed of 300 mm / min at 25 ° C. to a glass plate of the pressure-sensitive adhesive sheet of the present invention (in particular, the adhesive surface provided by the above-mentioned pressure-sensitive adhesive layer (pressure-sensitive adhesive layer of the present invention) for a glass plate 180° peeling adhesive strength at a tensile speed of 300 mm / min at 25 ° C.) is not particularly limited, but if the adhesive strength is high, sufficient adhesion to metal surfaces such as metal mesh wiring and silver nanowires can be obtained. From the viewpoint of improving the corrosion prevention effect, it is preferably 10 N/20 mm or more, more preferably 12 N/20 mm or more, still more preferably 14 N/20 mm or more, and even more preferably 16 N/20 mm or more. If the pressure-sensitive adhesive sheet of the present invention has a 180° peeling adhesive strength against a glass plate at 25°C and a tensile speed of 300 mm/min is a certain value or more, the adhesiveness to glass and the ability to prevent lifting on steps are further excellent. . The upper limit of the 180° peeling adhesive strength of the pressure-sensitive adhesive sheet of the present invention to a glass plate at 25°C at a tensile speed of 300 mm/min is not particularly limited, but for example, it is preferably 60 N/20 mm or less, more preferably 40 N. /20 mm or less.

180° peeling adhesive strength at a tensile speed of 300 mm / min at 65 ° C. to a glass plate of the pressure-sensitive adhesive sheet of the present invention (especially for the glass plate of the adhesive surface provided by the above-mentioned pressure-sensitive adhesive layer (pressure-sensitive adhesive layer of the present invention) 180° peeling adhesive strength at a tensile speed of 300 mm/min at 65°C) is not particularly limited, but from the viewpoint of improving adhesion reliability at high temperatures, it is preferably 6 N/20 mm or more, more preferably It is 6.5 N/20 mm or more, more preferably 7 N/20 mm or more, still more preferably 7.5 N/20 mm or more. If the pressure-sensitive adhesive sheet of the present invention has a 180° peeling adhesive strength against a glass plate at a tensile speed of 300 mm/min at 65°C and is a certain value or more, it has good adhesiveness to glass at high temperatures and prevention of lifting on steps. even better. The upper limit of the 180° peeling adhesive strength of the pressure-sensitive adhesive sheet of the present invention to a glass plate at 65°C at a tensile speed of 300 mm/min is not particularly limited, but for example, it is preferably 60 N/20 mm or less, more preferably 40 N. /20 mm or less.

The ratio of the 180° peeling adhesive force at a tensile speed of 300 mm/min at 65°C to the 180° peeling adhesive force at a tensile speed of 300 mm/min at 25°C to the glass plate of the pressure-sensitive adhesive sheet of the present invention (glass plate 180° peeling adhesive strength at a tensile speed of 300 mm / min at 65 ° C. / 180 ° peeling adhesive strength at a tensile speed of 300 mm / min at 25 ° C. against a glass plate × 100) is not particularly limited, but at high temperature From the viewpoint of improving adhesive strength and adhesion reliability, it is preferably 30 or more, more preferably 35 or more, even more preferably 40 or more, and even more preferably 45 or more. Since the elastic modulus of the pressure-sensitive adhesive layer decreases at high temperatures, the above ratio generally decreases. It is even more excellent in suppressing floating on steps. Although the upper limit of the ratio is not particularly limited, it may be 100 or less or 90 or less in practice.

The 180° peeling adhesive strength at a tensile speed of 300 mm/min at 25°C and 65°C to a glass plate is determined by the following method for measuring 180° peeling adhesive strength. Examples of the glass plate include, but are not particularly limited to, trade name "Soda Lime Glass #0050" (manufactured by Matsunami Glass Industry Co., Ltd.). In addition, non-alkali glass, chemically strengthened glass, and the like can also be used.

180° peeling adhesion of the adhesive sheet of the present invention to an acrylic plate at 25 ° C. at a tensile speed of 300 mm / min (particularly provided by the above adhesive layer (adhesive layer formed by the adhesive composition of the present invention) The 180° peeling adhesive strength at a tensile speed of 300 mm / min at 25 ° C. to the acrylic plate of the adhesive surface to be applied is not particularly limited, but if the adhesive strength is high, sufficient adhesion to the metal surface can be obtained and corrosion can be prevented. From the viewpoint of improving the effect, it is preferably 10 N/20 mm or more, more preferably 12 N/20 mm or more, and still more preferably 14 N/20 mm or more. When the adhesive sheet of the present invention has a 180° peeling adhesive force of 10 N/20 mm at a tensile speed of 300 mm / min at 25 ° C. to an acrylic plate, it has good adhesion to the acrylic plate and good suppression of lifting on steps. This is preferable because it makes it easier to obtain properties. The upper limit of the 180° peeling adhesive strength of the pressure-sensitive adhesive sheet of the present invention to an acrylic plate at 25°C at a tensile speed of 300 mm/min is not particularly limited, but is, for example, 40 N/20 mm, more preferably 60 N/ 20 mm. The 180° peeling adhesive strength at a tensile speed of 300 mm/min at 25°C to the acrylic plate is obtained by the following method for measuring 180° peeling adhesive strength.

Examples of the acrylic plate include, but are not limited to, a PMMA plate (trade name “Acrylite”, manufactured by Mitsubishi Rayon Co., Ltd.).

The adhesive strength and the adhesive strength ratio of the adhesive sheet of the present invention are determined by the monomer composition of the acrylic polymer (A), the type of the hydrogenated polyolefin resin (B), the acrylic polymer (A) and the hydrogenated polyolefin resin ( It can be adjusted by adjusting the compounding ratio of B).

(A-1. 180° peeling adhesive force measurement method)
The adhesive surface of the adhesive sheet is adhered to the adherend, pressed under the conditions of one reciprocation of a 2 kg roller, and aged for 30 minutes in an atmosphere of 23° C. and 50% RH. After aging, in accordance with JIS Z 0237, in an atmosphere of 25 ° C. or 65 ° C., 50% RH, under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 °, the adhesive sheet was peeled off from the adherend, 180 ° The peel adhesion (N/20 mm) is measured.

(B. Thickness)
The thickness (total thickness) of the adhesive sheet of the present invention is not particularly limited, but is preferably 12 to 350 μm, more preferably 12 to 300 μm. When the thickness is equal to or greater than a certain value, the stress with the metal wiring can be sufficiently relaxed, and display unevenness can be prevented, which is preferable. Further, when the thickness is less than a certain value, it is preferable in that an excellent appearance can be easily maintained during production or roll storage, and glue stains are less likely to occur during cutting. The thickness of the pressure-sensitive adhesive sheet of the present invention does not include the thickness of the release liner.

(C. Hayes)
The haze (according to JIS K7136) of the pressure-sensitive adhesive sheet of the present invention is not particularly limited, but is preferably 1.0% or less, more preferably 0.8% or less. A haze of 1.0% or less is preferable because excellent transparency and appearance can be obtained. Although the lower limit of haze is not particularly limited, it is theoretically 0%, and practically may be more than 0.01%. In addition, the haze can be measured by, for example, leaving the adhesive sheet in a normal state (23 ° C., 50% RH) for at least 24 hours, peeling off the release liner if it has, and sliding glass (for example, total light transmittance 92% haze and 0.2% haze) as a sample, and measured using a haze meter (manufactured by Murakami Color Research Laboratory, trade name "HM-150N") or its equivalent. can be done.

(D. Total light transmittance)
The total light transmittance (according to JIS K7361-1) in the visible light wavelength region of the adhesive sheet of the present invention is not particularly limited, but is preferably 90% or more, more preferably 91% or more, and still more preferably 92% or more. be. When the total light transmittance is 90% or more, excellent transparency and excellent appearance can be obtained, which is preferable. The upper limit of the total light transmittance is not particularly limited, but theoretically, it is a value excluding light loss (Fresnel loss) due to reflection occurring at the air interface from 100%, and in practice it may be 95% or less. . The above total light transmittance can be measured, for example, by leaving the pressure-sensitive adhesive sheet in a normal state (23° C., 50% RH) for at least 24 hours, peeling off the release liner, Light transmittance of 92%, haze of 0.2%) is used as a sample, and a haze meter (manufactured by Murakami Color Research Laboratory, trade name "HM-150N") or its equivalent is used. can be measured.

[2-2. Adhesive sheet manufacturing method]
Although the pressure-sensitive adhesive sheet of the present invention is not particularly limited, it is preferably manufactured according to a known or commonly used manufacturing method. For example, when the pressure-sensitive adhesive sheet of the present invention is a substrate-less pressure-sensitive adhesive sheet, it can be obtained by forming the pressure-sensitive adhesive layer on a release liner by the method described above. Further, when the pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet with a substrate, it may be obtained by directly forming the above-mentioned pressure-sensitive adhesive layer on the surface of the substrate (direct transfer method), or once the above pressure-sensitive adhesive layer is formed on a release liner. After forming the pressure-sensitive adhesive layer, it may be obtained by transferring (bonding) to the substrate, or by providing the above-mentioned pressure-sensitive adhesive layer on the substrate (transfer method).

[2-3. Adhesive Layer of Adhesive Sheet]
(Storage modulus at 25°C)
The storage elastic modulus at 25° C. of the pressure-sensitive adhesive layer of the present invention (the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention) is not particularly limited, but is preferably 0.01 MPa or more, more preferably 0.01 MPa or more. 05 MPa or more, more preferably 0.1 MPa or more. When the storage elastic modulus is 0.01 MPa or more, good adhesion reliability can be easily obtained, which is preferable. In addition, the storage elastic modulus of the adhesive layer at 25 ° C. can be realized in that a highly flexible adhesive layer can be realized, and the stress with the metal wiring can be sufficiently relaxed to prevent display unevenness. is preferably 0.5 MPa or less, more preferably 0.4 MPa or less. The storage elastic modulus of the pressure-sensitive adhesive layer is measured by dynamic viscoelasticity.

The storage modulus of the pressure-sensitive adhesive layer of the present invention depends on the monomer composition of the acrylic polymer (A), the type of the hydrogenated polyolefin resin (B), and the blending of the acrylic polymer (A) and the hydrogenated polyolefin resin (B). It can be adjusted by adjusting the ratio or the like.

(thickness)
The thickness of the pressure-sensitive adhesive layer (especially the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention) is not particularly limited, but is preferably 12-350 μm, more preferably 12-300 μm. When the thickness is equal to or greater than a certain value, the stress with the metal wiring can be sufficiently relaxed, and display unevenness can be prevented, which is preferable. In addition, when the thickness is a certain value or less, it is particularly excellent in handleability and manufacturability, which is preferable.

(Production method)
The method for producing the pressure-sensitive adhesive layer is not particularly limited. It is mentioned that

A known coating method may be used for applying (coating) the pressure-sensitive adhesive composition. For example, coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, and direct coaters may be used.

[2-4. Other layers of the adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention may have other layers in addition to the pressure-sensitive adhesive layer. Examples of other layers include other adhesive layers (adhesive layers other than the above adhesive layer (adhesive layers other than the adhesive layer formed from the adhesive composition of the present invention)), intermediate layers, and undercoats. layers and the like. In addition, the pressure-sensitive adhesive sheet of the present invention may have two or more other layers.

[2-5. Adhesive sheet base material]
When the pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet with a substrate, the substrate is not particularly limited, but examples thereof include various optical films such as plastic films, antireflection (AR) films, polarizing plates, and retardation plates. be done. Materials for the plastic film include, for example, polyester resins such as polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate, triacetyl cellulose (TAC), polysulfone, polyarylate, polyimide, Polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymer, trade name "Arton (cyclic olefin polymer, manufactured by JSR Corporation)", trade name "Zeonor (cyclic olefin polymer, Nippon Zeon Co., Ltd.) plastic materials such as cyclic olefin polymers such as ". These plastic materials may be used alone or in combination of two or more. Further, the above-mentioned "base material" is a part that is attached to the adherend together with the adhesive layer when the pressure-sensitive adhesive sheet is applied to the adherend. A release liner that is peeled off when the adhesive sheet is used (attached) is not included in the “base material”.

The substrate is preferably transparent. The total light transmittance (according to JIS K7361-1) of the base material in the visible light wavelength region is not particularly limited, but is preferably 85% or more, more preferably 88% or more. In addition, the haze of the substrate (according to JIS K7136) is not particularly limited, but is preferably 1.0% or less, more preferably 0.8% or less. Examples of such transparent substrates include PET films and non-oriented films such as the trade name "Arton" and the trade name "Zeonor".

Although the thickness of the substrate is not particularly limited, it is preferably 12 to 500 μm, for example. In addition, the substrate may have either a single-layer structure or a multilayer structure. In addition, the surface of the substrate may be appropriately subjected to known and commonly used surface treatments such as physical treatments such as corona discharge treatment and plasma treatment, and chemical treatments such as undercoating treatment.

[2-6. Release liner for adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention may be provided with a release liner on the pressure-sensitive adhesive surface until use. When the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, each pressure-sensitive adhesive surface may be protected by two release liners. It may be protected in a form wound in a shape. A release liner is used as a protective material for the pressure-sensitive adhesive layer, and is peeled off when applied to an adherend. Moreover, when the pressure-sensitive adhesive sheet of the present invention is a substrate-less pressure-sensitive adhesive sheet, the release liner also serves as a support for the pressure-sensitive adhesive layer. Note that the release liner may not necessarily be provided.

Examples of the release liner include, but are not limited to, a release liner having a release layer (release-treated layer) on at least one surface of a release liner substrate, a low-adhesion release liner made of a fluoropolymer, and a non-polar polymer. A low-adhesive release liner consisting of The fluorine-based polymer is not particularly limited, but examples include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-fluorine Examples include vinylidene copolymers. The non-polar polymer is not particularly limited, and examples thereof include olefin resins such as polyethylene (PE) and polypropylene (PP). Among them, it is preferable to use a release liner having a release layer on at least one surface of the release liner substrate.

Examples of the release liner base material include, but are not particularly limited to, plastic films. Examples of such plastic films include polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); polyethylene (PE), polypropylene (PP), polymethylpentene (PMP); ), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA) and other α-olefin-based resins as monomer components; polyvinyl chloride (PVC); vinyl acetate-based resins; polycarbonate (PC); Polyphenylene sulfide (PPS); amide-based resins such as polyamide (nylon) and wholly aromatic polyamide (aramid); polyimide-based resins; Among them, from the viewpoints of processability, availability, workability, dust resistance, cost, etc., plastic films formed from polyester-based resins are preferred, and PET films are more preferred.

The release agent constituting the release layer is not particularly limited, but examples thereof include release agents such as silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, and molybdenum sulfide. Of these, silicone-based release agents are preferred from the viewpoint of release control and stability over time. In addition, a peeling agent can be used individually or in combination of 2 or more types.

The release layer may be a single layer, or may have a laminated structure in which two or more layers are laminated as long as the characteristics of the present invention are not impaired.

Among them, a preferred specific configuration of the release liner is a configuration in which a PET film is used as the release liner base material, and a release layer is provided on at least one surface of the release liner base material using a silicone-based release treatment agent. is mentioned. Of the two surfaces of the release liner, the surface opposite to the side in contact with the pressure-sensitive adhesive layer and not provided with the release layer is sometimes referred to as the "back surface" of the release liner.

A carrier material may be laminated on the back surface of the release liner from the viewpoint of securing punching workability and handling properties and increasing the thickness while maintaining flexibility. Such a carrier material is not particularly limited, but for example, a configuration in which two layers of a PET film base material are laminated via an adhesive layer, a COP film base material and a PET film base material in which two layers are laminated via an adhesive layer. and the like. Note that the release liner need not have a carrier material.

In addition, the release liner has a conductive treatment layer on the release layer and/or the back from the viewpoint of suppressing electrification that occurs when the release liner is transported or peeled off, and reducing adhesion and contamination of foreign matter. good too. Such a conductive layer is not particularly limited, but for example, a coating treatment mainly composed of a composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) as a conductive polymer layers and the like. The release liner may not have a conductive layer.

The release liner can be manufactured by a known and commonly used method. The carrier material and conductive layer can be prepared by laminating them on the release layer and/or the back surface of the release liner by a known method. Moreover, the release liner of the present invention may have other layers (for example, an intermediate layer, an undercoat layer, etc.) within a range that does not impair the effects of the present invention.

The thickness of the release liner is not particularly limited, but is preferably 12 to 200 μm, more preferably 25 to 150 μm, and still more preferably 38 to 38 μm from the viewpoint of cost and handleability of the adhesive sheet during lamination. 125 μm.

When the pressure-sensitive adhesive sheet of the present invention is a double release liner type double-sided pressure-sensitive adhesive sheet, one pressure-sensitive adhesive surface is provided with a release liner, and the other pressure-sensitive adhesive surface is provided with a release liner. In such a case, both release liners are release liners having a release layer on only one surface (in particular, a release liner having a release layer made of a silicone-based release agent on one surface of a plastic substrate). is preferred. Also, the release liner is provided such that the release layer is in contact with the adhesive surface.

Furthermore, when the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet of a double release liner type, it is preferable that a difference be provided in the peel strength of the two release liners. For example, when the pressure-sensitive adhesive sheet of the present invention is a double release liner type double-sided pressure-sensitive adhesive sheet, one release liner is used for the pressure-sensitive adhesive surface (also referred to as "one side") that is used (attached) first, The other release liner is preferably used for the adhesive side (also referred to as "second side") that will be used (applied) later. Therefore, one release liner is used as a "light release side" release liner that can be released with a smaller force (release force), and the other release liner requires a larger force (release force) to release from the adhesive layer. It is preferably used as a "heavy release side" release liner that requires a In this specification, the release liner on the light release side may be referred to as "light release liner", and the release liner on the heavy release side may be referred to as "heavy release liner".

When the pressure-sensitive adhesive sheet of the present invention is a single release liner type double-sided pressure-sensitive adhesive sheet, one pressure-sensitive adhesive surface is provided with a release liner, and by winding this, the other pressure-sensitive adhesive surface of the pressure-sensitive adhesive is also covered by the release liner. protected. When the pressure-sensitive adhesive sheet of the present invention is a single release liner type, both surfaces of the release liner are preferably release layers (release treated layers). Of the two release layers of the release liner, the release layer on the side that comes into contact with the adhesive surface when wound is sometimes called a "back release layer". Usually, the back release layer side of the release liner is used for the "first side" of the double-sided PSA sheet.

Since the pressure-sensitive adhesive sheet of the present invention is imparted with stress relaxation properties without lowering the molecular weight of the acrylic polymer, it suppresses roughness and deformation of the adhesive surface of the pressure-sensitive adhesive layer and the occurrence of stick-slip when the release liner is peeled off. , is preferable in that the pressure-sensitive adhesive sheet can be stably used. Note that stick-slip is a vibration phenomenon that occurs on the peeling surface, and damages and breaks the adherend, or partially leaves an adhesive residue on the adherend.

When the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, the adhesive layer of the pressure-sensitive adhesive layer is prevented from becoming rough or deformed when the release liner is peeled off, and the occurrence of stick-slip is suppressed, so that the pressure-sensitive adhesive sheet can be used stably. The peel force (release liner peel force) on one side (light release side) of the release liner against the adhesive layer is 0.01 to 0.5 N/50 mm, preferably 0.05 to 0.25 N/50 mm. , the release force (release liner release force) on the second side (heavy release side) of the release liner against the pressure-sensitive adhesive layer (for example, the acrylic pressure-sensitive adhesive layer, the rubber-based pressure-sensitive adhesive layer, etc.) is 0.1 to 1. 00 N/50 mm, preferably 0.2 to 0.85 N/50 mm, the release liner release force on the heavy release surface side is always greater than the release liner release force on the light release surface side, and 1.1 to 10. It is preferable that there is a peeling difference of about 0 times.

In particular, when the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, the so-called separation phenomenon, roughening and deformation of the adhesive surface of the pressure-sensitive adhesive layer when the release liner is peeled off, and the occurrence of stick-slip are suppressed, and the pressure-sensitive adhesive sheet is stabilized. From the point of view of usability, the difference between the peeling force of the heavy release liner to the adhesive layer (release liner peeling force) and the peeling force of the light release liner to the adhesive layer (release liner peeling force) is 0.01 N / 50 mm 0.02 N/50 mm or more, more preferably 0.05 N/50 mm or more, and particularly preferably 0.06 N/50 mm or more.

The release liner peel strength means the 180° peeling adhesive strength of the release liner to the pressure-sensitive adhesive layer as measured by a 180° peel test. The tensile speed is 300 mm/min.

[2-7. Uses of the adhesive sheet, etc.]
Since the pressure-sensitive adhesive sheet of the present invention has the pressure-sensitive adhesive layer of the present invention (the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention), the appearance of display devices and input devices is less likely to deteriorate under low pressure conditions. In addition, even when a film having metal wiring such as a metal mesh film or a silver nanowire film is bonded together, it is possible to prevent display unevenness of a display device or an input device. Furthermore, it is excellent in adhesiveness, anti-foaming peeling property, and step followability. Therefore, the optical member having the pressure-sensitive adhesive sheet of the present invention is less likely to deteriorate in appearance under low-pressure conditions, has high flexibility, and can sufficiently relax the stress with the metal wiring to prevent display unevenness. Also, it is excellent in adhesion reliability, especially at high temperature.

Therefore, the pressure-sensitive adhesive sheet of the present invention is useful for bonding films having metal wiring such as metal mesh films and silver nanowire films. Moreover, the pressure-sensitive adhesive sheet of the present invention is also useful for adherends that tend to foam at the interface at high temperatures. For example, polymethyl methacrylate (PMMA) may contain unreacted monomers, and foaming due to foreign matter is likely to occur at high temperatures. Polycarbonate (PC) also tends to outgas water and carbon dioxide at high temperatures. Since the pressure-sensitive adhesive sheet of the present invention is excellent in resistance to foaming and peeling, it is also useful for plastic adherends containing such resins.

Moreover, the pressure-sensitive adhesive sheet of the present invention is useful not only for adherends with a small coefficient of linear expansion, but also for adherends with a large coefficient of linear expansion. The adherend having a small linear expansion coefficient is not particularly limited, but examples thereof include glass plates (linear expansion coefficient: 0.3×10 ⁻⁵ to 0.8×10 ⁻⁵ /° C.), polyethylene terephthalate groups, material (PET film, coefficient of linear expansion: 1.5×10 ⁻⁵ to 2×10 ⁻⁵ /° C.). The adherend having a large coefficient of linear expansion is not particularly limited, but examples thereof include resin substrates having a large coefficient of linear expansion. 7×10 ⁻⁵ to 8×10 ⁻⁵ /° C.), polymethyl methacrylate resin substrate (PMMA, linear expansion coefficient: 7×10 ⁻⁵ to 8×10 ⁻⁵ /° C.), cycloolefin polymer substrate ( COP, coefficient of linear expansion: 6×10 ⁻⁵ to 7×10 ⁻⁵ /° C.), trade name “Zeonor” (manufactured by Nippon Zeon Co., Ltd.), trade name “Arton” (manufactured by JSR Corporation), and the like.

The pressure-sensitive adhesive sheet of the present invention is useful for bonding an adherend with a small coefficient of linear expansion and an adherend with a large coefficient of linear expansion. Specifically, the pressure-sensitive adhesive sheet of the present invention is preferably used for bonding a glass adherend (for example, a glass plate, chemically strengthened glass, glass lens, etc.) to the resin substrate having a large coefficient of linear expansion.

Thus, the pressure-sensitive adhesive sheet of the present invention is useful for bonding adherends made of various materials, and is particularly useful for bonding glass adherends and plastic adherends. The plastic adherend may be an optical film such as a plastic film having metal mesh wiring, silver nanowires, or the like on its surface.

Furthermore, the pressure-sensitive adhesive sheet of the present invention can be applied not only to adherends having a smooth surface but also to adherends having uneven surfaces, such as metal mesh films, silver nanowire films, and other films having metal wiring. , usefully used. In particular, the pressure-sensitive adhesive sheet of the present invention can be used even if at least one of the glass adherend and the resin substrate having a large coefficient of linear expansion has steps on the surface. It is useful for lamination with large resin substrates.

The pressure-sensitive adhesive sheet of the present invention is preferably used for manufacturing portable electronic devices. Examples of the portable electronic devices include mobile phones, PHS, smartphones, tablets (tablet computers), mobile computers (mobile PCs), personal digital assistants (PDA), electronic notebooks, portable televisions, portable radios, and the like. type broadcast receivers, portable game machines, portable audio players, portable DVD players, cameras such as digital cameras, and camcorder type video cameras.

The pressure-sensitive adhesive sheet of the present invention is preferably used, for example, for attaching members or modules constituting a portable electronic device to each other, fixing members or modules constituting a portable electronic device to a housing, or the like. More specifically, bonding of cover glass or lens (especially glass lens) with touch panel or touch sensor (especially film having metal wiring such as metal mesh film or silver nanowire film), polarizing plate and touch panel or touch Bonding with sensors, bonding display panels with touch panels and touch sensors, fixing cover glass and lenses (especially glass lenses) to housings, fixing display panels to housings, sheet keyboards, touch panels, etc. Fixing the input device to the housing, bonding the protection panel of the information display part to the housing, bonding the housings to each other, bonding the housing to the decorative sheet, various members and Examples include fixing and pasting of modules. In this specification, the display panel refers to a structure composed of at least a lens (particularly a glass lens) and a touch panel. Further, the term "lens" used herein is a concept that includes both a transparent body that exhibits light refraction and a transparent body that does not have light refraction. In other words, a lens in this specification also includes a mere window panel that has no refractive effect.

Furthermore, the pressure-sensitive adhesive sheet of the present invention is preferably used for optical applications. That is, the pressure-sensitive adhesive sheet of the present invention is preferably an optical pressure-sensitive adhesive sheet for optical applications. More specifically, for example, it is preferably used for bonding optical members (for bonding optical members) or for manufacturing products (optical products) using the optical member.

[3. Optical member]
The optical member of the present invention is an optical member comprising at least the pressure-sensitive adhesive sheet and a substrate, wherein the substrate is provided with metal wiring (for example, metal mesh wiring, silver nanowires, etc.) on at least one side thereof, and the metal wiring of the substrate is It is sufficient that the pressure-sensitive adhesive layer of the present invention (the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention) is adhered on the side having the wiring, and other points are not particularly limited. The pressure-sensitive adhesive sheet of the present invention may be provided with a release liner on the pressure-sensitive adhesive surface until use. do not.

From the viewpoint of obtaining a more excellent corrosion prevention effect, the optical member preferably has the pressure-sensitive adhesive layer on the side opposite to the side of the substrate having the metal wiring, and the side of the substrate having the metal wiring. It is more preferable that the pressure-sensitive adhesive layer is adhered on the side opposite to the side.

Materials constituting the metal wiring are not particularly limited, but examples include titanium, silicon, niobium, indium, zinc, tin, gold, silver, copper, aluminum, cobalt, chromium, nickel, lead, iron, palladium, and platinum. , tungsten, zirconium, tantalum and hafnium. Furthermore, materials containing two or more of these metals and alloys containing these metals as main components are also included. Among them, gold, silver, and copper are preferred from the viewpoint of conductivity, and silver and copper are more preferred from the viewpoint of conductivity and cost. That is, the metal wiring is preferably silver wiring and/or copper wiring, particularly copper mesh wiring, silver mesh wiring, or silver nanowire. Moreover, an oxide film or a metal coating film may be provided on the metal wiring for the purpose of higher rust prevention. It should be noted that the same applies to materials constituting metal wiring of a touch panel described later.

An optical member refers to a member having optical properties (e.g., polarization, light refraction, light scattering, light reflection, light transmission, light absorption, light diffraction, optical rotation, visibility, etc.). . The substrate constituting the optical member is not particularly limited. For example, polarizing plate, wave plate, retardation plate, optical compensation film, brightness enhancement film, light guide plate, reflective film, antireflection film, hard coat film (hard coat treatment is applied to at least one side of plastic film such as PET film). films), transparent conductive films (for example, plastic films having an ITO layer on the surface (preferably ITO films such as PET-ITO, polycarbonate, cycloolefin polymer, etc.), design films, decorative films, surface protection plates, prisms , lenses, color filters, transparent substrates (glass sensors, glass display panels (LCD, etc.), glass substrates such as glass plates with transparent electrodes, etc.), and substrates on which these are laminated (these are collectively referred to as " (sometimes referred to as "functional film"). Moreover, these films may have a metal nanowire layer, a conductive polymer layer, or the like. Further, these films may be mesh-printed with thin metal wires. The above-mentioned "plate" and "film" include forms such as plate-like, film-like, and sheet-like, respectively. For example, "polarizing film" includes "polarizing plate" and "polarizing sheet". . In addition, "film" shall include film sensors and the like.

In particular, the pressure-sensitive adhesive sheet of the present invention is suitably used for a transparent conductive film (metal mesh film, silver nanowire film) in which the metal wiring is metal mesh wiring or silver nanowires, particularly an optical member having a metal mesh film. be able to. When an optical member having metal wiring such as a metal mesh film or a silver nanowire film is pasted together via an adhesive sheet, the peripheral edge of the image display panel may be damaged due to stress strain added to the adhesive around the metal wiring. There is a problem that display unevenness is likely to occur in some areas. Therefore, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet to which the optical member having the metal wiring is adhered is required to have flexibility for relieving stress with the metal wiring in order to prevent display unevenness. However, in order to prevent display unevenness, display devices and input devices that include optical members bonded together using a highly flexible adhesive sheet, for example, under low pressure conditions such as manufacturing processes, cargo compartments of passenger aircraft, and high altitudes. There is a problem that the appearance deteriorates under

In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer of the present invention has high flexibility, and even when a film having metal wiring such as a metal mesh film or a silver nanowire film is laminated, the stress with the metal wiring is sufficiently removed. It can be alleviated and display unevenness can be prevented. In addition, a display device or an input device having the pressure-sensitive adhesive sheet of the present invention is less likely to deteriorate in appearance even under low-pressure conditions. The same applies to a metal mesh film and a silver nanowire film that constitute a touch panel described later.

Examples of the display device include a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), electronic paper, and the like. Moreover, a touch panel etc. are mentioned as said input device.

The substrate constituting the optical member is not particularly limited. etc.). As described above, the "optical member" in the present invention includes members (design films, decorative films, surface protective films, etc.) that play a role of decoration and protection while maintaining the visibility of display devices and input devices. shall be taken.

If the pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet with a substrate and the pressure-sensitive adhesive sheet constitutes a member having optical properties, the substrate can be regarded as the substrate, and the pressure-sensitive adhesive sheet is the optical member of the present invention. It can be said that it is.

When the pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet with a substrate and the functional film is used as the substrate, the pressure-sensitive adhesive sheet of the present invention has the pressure-sensitive adhesive layer on at least one side of the functional film. It can also be used as an "adhesive functional film".

Next, a specific example of a particularly preferred embodiment of the optical member of the present invention will be described with reference to the schematic diagram of FIG.

FIG. 1 shows an optical member having at least a substrate which is an adhesive sheet 10 and a metal mesh film 11, wherein the metal mesh film 11 has metal mesh wiring 3 on one side, and the adhesive sheet 10 is the metal mesh film 11. An optical member 1 is shown that is adhered on the side having mesh wirings 3 .

[4. touch panel]
The touch panel of the present invention is a touch panel having at least the pressure-sensitive adhesive sheet and a substrate, wherein the substrate has metal wiring (e.g., metal mesh wiring, silver nanowires, etc.) on one side, and the side of the substrate having the metal wiring. It is sufficient that the pressure-sensitive adhesive layer is adhered to the surface of the substrate, and other points are not particularly limited. Since the pressure-sensitive adhesive sheet in the touch panel of the present invention is a pressure-sensitive adhesive sheet for use, it does not have a release liner.

As the touch panel, the optical member of the present invention may or may not necessarily have the above-mentioned pressure-sensitive adhesive sheet. It is preferable from the viewpoint of obtaining an effect.). Further, the separate optical member may be singular or plural.

In the case of the above mode, the mode of laminating the optical member of the present invention and the other optical member is not particularly limited. (2) A mode in which the pressure-sensitive adhesive sheet of the present invention containing or constituting an optical member is bonded to another optical member; (3) an optical member via the pressure-sensitive adhesive tape of the present invention; to a member other than an optical member, and (4) a mode in which the pressure-sensitive adhesive tape of the present invention containing or constituting an optical member is laminated to a member other than the optical member. In the aspect (2) above, the pressure-sensitive adhesive sheet of the present invention is preferably a double-sided pressure-sensitive adhesive sheet whose substrate is an optical member (for example, an optical film or the like).

Next, a specific example of a particularly preferable aspect of the touch panel of the present invention will be described with reference to the schematic diagram of FIG.

FIG. 2A shows a touch panel 2A having a transparent substrate 12a, an adhesive sheet 10a, a metal mesh film 11a, an adhesive sheet 10b, and a transparent substrate 12b in contact with each other in this order. The metal mesh film 11a has the metal mesh wiring 3 on the adhesive sheet 10b side, and the adhesive sheet 10b is adhered to the metal mesh wiring 3 side of the metal mesh film 11a. The transparent substrates 12a and 12b are preferably made of glass, and the substrate of the metal mesh film 11a is preferably made of PET. The pressure-sensitive adhesive sheet 10a may be the pressure-sensitive adhesive sheet of the present invention, or may not be the pressure-sensitive adhesive sheet of the present invention, but is preferably the pressure-sensitive adhesive sheet of the present invention.

FIG. 2B shows a touch panel 2B having a transparent substrate 12a, an adhesive sheet 10a, a metal mesh film 13a, an adhesive sheet 10b, a polarizing plate 14, and a transparent substrate 12b in contact with each other in this order. Metal mesh film 13a has metal mesh wiring 3 on the surface facing adhesive sheet 10b, and adhesive sheet 10b is adhered to the surface of metal mesh film 13a having metal mesh wiring 3. FIG. The transparent substrate 12a is preferably glass, and the transparent substrate 12b is preferably a glass display panel such as LCD. The pressure-sensitive adhesive sheet 10a may or may not be configured with the above-described pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention). It is preferably composed of a pressure-sensitive adhesive layer) formed from an adhesive composition.

FIG. 2C shows a touch panel 2C having a transparent substrate 12a, an adhesive sheet 10a, a metal mesh film 11b, an adhesive sheet 10b, and a transparent substrate 12b in this order in contact with each other. The metal mesh film 11b has metal mesh wirings 3a and 3b on both sides, respectively. is adhered to the surface of the metal mesh film 11b on the side having the metal mesh wiring 3b. The transparent substrates 12a and 12b are preferably made of glass, and the substrate of the metal mesh film 11b is preferably made of PET. At least one of adhesive sheet 10a and adhesive sheet 10b may be the adhesive sheet of the present invention, but both adhesive sheet 10a and adhesive sheet 10b are preferably adhesive sheets of the present invention.

FIG. 2D shows a touch panel 2D having a transparent substrate 12a, an adhesive sheet 10a, a metal mesh film 13b, an adhesive sheet 10b, a polarizing plate 14, and a transparent substrate 12b in contact with each other in this order. The metal mesh film 13b has metal mesh wirings 3a and 3b on both sides, respectively. is adhered to the surface of the metal mesh film 13b on the side having the metal mesh wiring 3b. The transparent substrate 12a is preferably glass, and the transparent substrate 12b is preferably a glass display panel such as LCD. At least one of the adhesive sheet 10a and the adhesive sheet 10b may be composed of the adhesive layer (the adhesive layer formed from the adhesive composition of the present invention), but both the adhesive sheet 10a and the adhesive sheet 10b It is preferably composed of the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention).

The method of forming the metal mesh wiring on the metal mesh film is not particularly limited, but examples thereof include a method of removing a previously provided metal layer by etching or the like, a printing method, and the like.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. All of the compounding parts (parts by weight) indicate the compounding parts of each component described.

[Production Example 1: Preparation of prepolymer composition A]
40.5 parts by weight of 2-ethylhexyl acrylate (2EHA), 40.5 parts by weight of isostearyl acrylate (ISTA), 18 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 4-hydroxybutyl acrylate (4 -HBA) to a monomer mixture composed of 1 part by weight, 0.05 parts by weight of a photopolymerization initiator (trade name "Omnirad 184", manufactured by IGM Resins B.V.), and a photopolymerization initiator (trade name "Omnirad 651" , IGM Resins B.V.) After blending 0.05 parts by weight, the viscosity (BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30 ° C.) is irradiated with ultraviolet rays until it reaches about 20 Pa s, A prepolymer composition A was obtained in which a part of the above monomer component was polymerized.

[Production Example 2: Preparation of prepolymer composition B]
56 parts by weight of 2-ethylhexyl acrylate (2EHA), 24 parts by weight of isostearyl acrylate (ISTA), 14 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 6 parts by weight of 4-hydroxybutyl acrylate (4-HBA) 0.035 parts by weight of a photopolymerization initiator (trade name "Omnirad 184", manufactured by IGM Resins B.V.) and a photopolymerization initiator (trade name "Omnirad 651", IGM Resins B V. Co., Ltd.) was blended, and then irradiated with ultraviolet rays until the viscosity (BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30 ° C.) reached about 20 Pa s, and the above monomer component was removed. A partially polymerized prepolymer composition B was obtained.

[Production Example 3: Preparation of prepolymer composition C]
56 parts by weight of 2-ethylhexyl acrylate (2EHA), 24 parts by weight of isostearyl acrylate (ISTA), 19 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 1 part by weight of 4-hydroxybutyl acrylate (4-HBA) 0.035 parts by weight of a photopolymerization initiator (trade name "Omnirad 184", manufactured by IGM Resins B.V.) and a photopolymerization initiator (trade name "Omnirad 651", IGM Resins B V. Co., Ltd.) was blended, and then irradiated with ultraviolet rays until the viscosity (BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30 ° C.) reached about 20 Pa s, and the above monomer component was removed. A partially polymerized prepolymer composition C was obtained.

[Example 1]
To 100 parts by weight of the prepolymer composition A obtained in Production Example 1, hydrogenated 1,2-polybutadiene (trade name “BI-3000”, number average molecular weight (Mn): 4750 (actual value), weight average molecular weight (Mw ): 6150 (measured value), polydispersity (Mw / Mn): 1.30 (measured value), hydrogenation rate: 97% or more (catalog value), iodine value: 21 or less (catalog value), Nippon Soda ( Co., Ltd.) 3 parts by weight, hydrogenated 1,2-polybutadiene glycol (trade name “GI-2000”, number average molecular weight (Mn): 3110 (actual value), weight average molecular weight (Mw): 5090 (actual value ), polydispersity (Mw / Mn): 1.64 (measured value), hydrogenation rate: 93% or more (catalog value), iodine value: 21 or less (catalog value), manufactured by Nippon Soda Co., Ltd.) 12 Parts by weight, 0.040 parts by weight of trimethylolpropane triacrylate (TMPTA), and 0.3 parts by weight of a silane coupling agent (trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added and mixed. , to obtain an adhesive composition (pre-curing composition).

The pressure-sensitive adhesive composition was applied onto a polyethylene terephthalate (PET) release liner (heavy release liner, product name “MRF75”, manufactured by Mitsubishi Plastics, Inc.) so that the final thickness (thickness of the pressure-sensitive adhesive layer) was 150 μm. It was applied to form a coating layer (adhesive composition layer). Next, a PET release liner (light release liner, trade name "MRE75", manufactured by Mitsubishi Plastics, Inc.) was provided on the coating layer to cover the coating layer and block oxygen. Then, a laminate of MRF75/coating layer (adhesive composition layer)/MRE75 was obtained.
Next, this laminate was irradiated with ultraviolet rays with an illuminance of 5 mW/cm ² for 300 seconds from the upper surface (MRF 38 side) of the laminate using a black light (manufactured by Toshiba Corporation). Further, drying treatment was performed for 2 minutes in a drier at 90° C. to volatilize the residual monomer. Thus, a substrate-less double-faced pressure-sensitive adhesive sheet consisting of only the pressure-sensitive adhesive layer and having both sides of the pressure-sensitive adhesive layer protected by release liners was obtained.

[Examples 2 to 10, Comparative Examples 1 to 3]
A substrate-less double-sided pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the composition of the pressure-sensitive adhesive composition and the thickness of the pressure-sensitive adhesive layer shown in Table 1 were used.

Details of the components shown in Table 1 are as follows.
(Prepolymer composition)
A: Prepolymer composition A produced in Production Example 1
B: Prepolymer composition B produced in Production Example 2
C: Prepolymer composition C produced in Production Example 3

(Hydrogenated polyolefin)
BI-2000: trade name "BI-2000", hydrogenated 1,2-polybutadiene, number average molecular weight (Mn): 2930 (measured value), weight average molecular weight (Mw): 4050 (measured value), polydispersity ( Mw / Mn): 1.38 (measured value), hydrogenation rate: 97% or more (catalog value), iodine value: 21 or less (catalog value), Nippon Soda Co., Ltd. GI-2000: product name “GI -2000", hydrogenated 1,2-polybutadiene glycol, number average molecular weight (Mn): 3110 (measured value), weight average molecular weight (Mw): 5090 (measured value), polydispersity (Mw/Mn): 1. 64 (measured value), hydrogenation rate: 97% or more (catalog value), iodine value: 21 or less (catalog value), manufactured by Nippon Soda Co., Ltd.

(polyfunctional acrylate)
TMPTA: trimethylolpropane triacrylate (chain transfer agent)
α-Thioglycerol (silane coupling agent)
KBM-403: trade name "KBM-403", 3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.

The number average molecular weight (Mn), weight average molecular weight (Mw), and polydispersity (Mw/Mn) of the hydrogenated polyolefin and non-hydrogenated polyolefin were measured by GPC (gel permeation chromatography) under the following conditions. It is obtained from the value calculated by polystyrene conversion.
Analyzer: GPC: HLC-8320GPC (Tosoh)
Measurement condition:
Column: TSKgel SuperHZM-H/HZ4000/HZ3000/HZ2000
Column size: 6.0 mm I.D. D. ×150mm
Eluent: THF (tetrahydrofuran)
Flow rate: 0.6mL/min
Detector: differential refractometer (RI)
Column temperature: 40°C
Injection volume: 20 μL
The molecular weight was calculated in terms of polystyrene.

[Characteristic evaluation]
The following measurements or evaluations were performed on the substrate-less double-sided pressure-sensitive adhesive sheets of Examples and Comparative Examples. The evaluation results are shown in Table 2.

(1) 300% Tensile Residual Stress The substrate-less double-sided pressure-sensitive adhesive sheets of Examples and Comparative Examples were cut into a size of 4 cm × 4 cm, folded twice so as not to trap air bubbles in the center, and had a width of 1 cm and a length of 4 cm. , a sample (adhesive layer) having a thickness of 600 μm was obtained.
In an environment of 23 ° C., the obtained sample was pulled in the longitudinal direction at a chuck distance of 20 mm and a tensile speed of 200 mm / min to an elongation (strain) of 300% (60 mm) (80 mm between chucks after pulling). Holding the elongation, the tensile stress (N) applied to the sample after 300 seconds have passed since the end of pulling was obtained, and the tensile stress was divided by the initial cross-sectional area (cross-sectional area before pulling) of the sample (N / cm ² ) was taken as 300% tensile residual stress. The initial elongation of the sample is 100%.

(2) Gel fraction Adhesive layer: About 0.1 g was collected from the double-sided adhesive sheet and wrapped in a porous tetrafluoroethylene sheet (trade name: "NTF1122", manufactured by Nitto Denko Corporation) having an average pore size of 0.2 µm. After that, it was tied with a kite string, and the weight at that time was measured, and the weight was taken as the weight before immersion. The weight before immersion is the total weight of the adhesive layer (the adhesive layer collected above), the tetrafluoroethylene sheet, and the kite string. Also, the total weight of the tetrafluoroethylene sheet and the kite string is measured, and this weight is taken as the weight of the package.
Next, the adhesive layer wrapped with a tetrafluoroethylene sheet and tied with a kite string (referred to as a “sample”) was placed in a 50 ml container filled with ethyl acetate and allowed to stand at 23° C. for 7 days. After that, remove the sample (after ethyl acetate treatment) from the container, transfer it to an aluminum cup, dry it in a dryer at 130 ° C. for 2 hours to remove ethyl acetate, measure the weight, and immerse the weight. After weight.
Then, the gel fraction was calculated from the following formula."
Gel fraction [% (% by weight)] = (XY) / (ZY) x 100

(3) Low pressure test Vacuum press at 100 Pa or less, pressure 0.2 to 0.5 MPa, press for 5 seconds to bond, and then autoclave (50 ° C. × 0.5 Mpa × 15 min) by charging, as a sample, a glass plate / A 5 cm×10 cm display panel having a laminated structure of polarizing plate/adhesive layer/glass plate was prepared. The thickness of the glass plate is 700 µm, the thickness of the polarizing plate is 115 µm (polarizing plate 95 + polarizing plate glue 20) µm, and the thickness of the adhesive layer is 150 µm. The display panel was allowed to stand in a constant temperature bath under heating and depressurizing conditions of 23800 Pa and 65° C. for 8 hours. After the display panel was taken out of the constant temperature bath and allowed to stand at normal pressure and room temperature for 30 minutes, the size and number of voids were visually measured and evaluated according to the following criteria.

A: The number of voids with a diameter of 300 μm or more is 0 and the number of voids with a diameter of 50 or more and less than 300 μm is 0
○: The number of voids with a diameter of 300 µm or more is 0 and the number of voids with a diameter of 50 or more and less than 300 µm is 1 or more and less than 10 △: The number of voids with a diameter of 300 µm or more is 1 or more and less than 10, or a diameter of 50 The number of voids with a diameter of 300 µm or more is 10 or more and less than 20 x ... The number of voids with a diameter of 300 µm or more is 10 or more, or the number of voids with a diameter of 50 or more and less than 300 µm is 20 or more

Variations of the present invention are appended below.
[Appendix 1] A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer,
A pressure-sensitive adhesive sheet having less than 10 voids with a diameter of 300 µm or more and less than 20 voids with a diameter of 50 or more and less than 300 µm in the following low pressure test.
<Low pressure test>
As a sample, a 5 cm×10 cm display panel having a laminated structure of glass plate/polarizing plate/adhesive layer/glass plate is prepared. The thickness of the glass plate is 700 µm, the thickness of the polarizing plate is 115 µm (polarizing plate 95 + polarizing plate glue 20) µm, and the thickness of the adhesive layer is 150 µm. The display panel is allowed to stand at 23,800 Pa under heating and decompressing conditions of 65° C. for 8 hours, and after 30 minutes under normal pressure and room temperature, the size and number of voids are visually measured.
[Appendix 2] The pressure-sensitive adhesive sheet according to Appendix 1, wherein the maximum diameter of the void in the low pressure test is 600 μm or less.
[Appendix 3] The adhesive sheet according to Appendix 1 or 2, wherein the adhesive layer has a gel fraction of 50% or more.
[Appendix 4] The pressure-sensitive adhesive sheet according to any one of Appendices 1 to 3, wherein the pressure-sensitive adhesive layer has a 300% tensile residual stress of 5 N/cm ² or less.
[Appendix 5] Any one of Appendices 1 to 4, wherein the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing an acrylic polymer (A) and a hydrogenated polyolefin resin (B). adhesive sheet.
[Appendix 6] The pressure-sensitive adhesive layer comprises a mixture of monomer components constituting the acrylic polymer (A) or a partial polymer of a mixture of monomer components constituting the acrylic polymer (A), and a hydrogenated polyolefin resin (B ), the pressure-sensitive adhesive sheet according to any one of Appendices 1 to 4, which is formed from the pressure-sensitive adhesive composition containing
[Appendix 7] The pressure-sensitive adhesive sheet according to Appendix 5 or 6, wherein the acrylic polymer (A) contains a (meth)acrylic acid alkyl ester having an alkyl group having 8 or more carbon atoms as a constituent monomer component.
[Appendix 8] The adhesive sheet according to any one of Appendices 5 to 7, wherein the hydrogenated polyolefin resin (B) contains a hydrogenated polyolefin.
[Appendix 9] The adhesive sheet according to Appendix 8, wherein the hydrogenated polyolefin resin (B) further contains a hydrogenated polyolefin polyol.
[Appendix 10] The pressure-sensitive adhesive sheet according to any one of Appendices 1 to 9, which has a thickness of 12 to 350 μm.
[Appendix 11] An optical member comprising at least the pressure-sensitive adhesive sheet according to any one of Appendices 1 to 10 and a substrate, wherein the substrate has metal wiring on at least one side thereof, and the side of the substrate having the metal wiring An optical member having the pressure-sensitive adhesive sheet adhered to the surface thereof.
[Appendix 12] The optical member according to Appendix 11, wherein the metal wiring is metal mesh wiring or silver nanowires.
[Appendix 13] A touch panel having at least the adhesive sheet according to any one of Appendices 1 to 10 and a substrate, wherein the substrate has metal wiring on at least one side, and the surface of the substrate on the side having the metal wiring A touch panel having the adhesive sheet adhered thereon.
[Appendix 14] The touch panel according to Appendix 13, wherein the metal wiring is metal mesh wiring or silver nanowires.

1 optical member 2A to 2D touch panel 3, 3a, 3b metal mesh wiring 10a, 10b adhesive sheet 11a, 11b metal mesh film 12a, 12b transparent substrate 13a, 13b metal mesh film 14 polarizing plate

Claims (17)

A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer,
A pressure-sensitive adhesive sheet having less than 10 voids with a diameter of 300 µm or more and less than 20 voids with a diameter of 50 or more and less than 300 µm in the following low pressure test.
<Low pressure test>
As a sample, a 5 cm×10 cm display panel having a laminated structure of glass plate/polarizing plate/adhesive layer/glass plate is prepared. The thickness of the glass plate is 700 µm, the thickness of the polarizing plate is 115 µm (polarizing plate 95 + polarizing plate glue 20) µm, and the thickness of the adhesive layer is 150 µm. The display panel is allowed to stand at 23,800 Pa under heating and decompressing conditions of 65° C. for 8 hours, and after 30 minutes under normal pressure and room temperature, the size and number of voids are visually measured. The pressure-sensitive adhesive sheet according to claim 1, wherein the maximum diameter of the voids in the low pressure test is 600 µm or less. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer has a gel fraction of 50% or more. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer has a 300% tensile residual stress of 5 N/cm ² or less. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing an acrylic polymer (A) and a hydrogenated polyolefin resin (B). The pressure-sensitive adhesive layer contains a mixture of monomer components constituting the acrylic polymer (A) or a partial polymer of a mixture of monomer components constituting the acrylic polymer (A), and a hydrogenated polyolefin resin (B). The pressure-sensitive adhesive sheet according to claim 1 or 2, which is formed from the pressure-sensitive adhesive composition. The pressure-sensitive adhesive sheet according to claim 5, wherein the acrylic polymer (A) contains a (meth)acrylic acid alkyl ester having an alkyl group having 8 or more carbon atoms as a constituent monomer component. The adhesive sheet according to claim 6, wherein the acrylic polymer (A) contains a (meth)acrylic acid alkyl ester having an alkyl group having 8 or more carbon atoms as a constituent monomer component. The adhesive sheet according to claim 5, wherein the hydrogenated polyolefin resin (B) contains hydrogenated polyolefin. The adhesive sheet according to claim 6, wherein the hydrogenated polyolefin resin (B) contains hydrogenated polyolefin. The adhesive sheet according to claim 9, wherein the hydrogenated polyolefin resin (B) further contains a hydrogenated polyolefin polyol. The adhesive sheet according to claim 10, wherein the hydrogenated polyolefin resin (B) further contains a hydrogenated polyolefin polyol. 3. The pressure-sensitive adhesive sheet according to claim 1, which has a thickness of 12 to 350 μm. 3. An optical member comprising at least the pressure-sensitive adhesive sheet according to claim 1 or 2 and a substrate, wherein the substrate has metal wiring on at least one side thereof, and the pressure-sensitive adhesive sheet is pasted on the side of the substrate having the metal wiring. attached optical member. 15. The optical member according to claim 14, wherein the metal wiring is metal mesh wiring or silver nanowires. 3. A touch panel comprising at least the pressure-sensitive adhesive sheet according to claim 1 or 2 and a substrate, wherein the substrate has metal wiring on at least one side thereof, and the pressure-sensitive adhesive sheet is adhered to the side of the substrate having the metal wiring. touch panel. The touch panel according to claim 16, wherein the metal wiring is metal mesh wiring or silver nanowires.

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