KR102413010B1 - Adhesive sheet - Google Patents

Abstract

The present invention provides an adhesive sheet having high adhesion to various adherends and excellent in foaming resistance (blister resistance) and step followability.
The pressure-sensitive adhesive sheet of the present invention comprises, as a monomer unit constituting a polymer, a (meth)acrylic acid ester polymer comprising a monomer having an alicyclic structure and a monomer having a nitrogen atom; and an active energy ray-curable component; characterized in that it is formed of a pressure-sensitive adhesive composition comprising a. The (meth)acrylic acid ester polymer is a monomer unit constituting the polymer, and contains 3% by mass or more and 20% by mass or less of the monomer having an alicyclic structure, and 1% by mass or more and 20% by mass or more of the monomer having a nitrogen atom. It is preferable to contain below.

Description

Adhesive sheet {ADHESIVE SHEET}

The present invention relates to an adhesive sheet.

In recent years, various mobile electronic devices, such as a mobile phone and a tablet terminal, are equipped with the display body (display) using the display panel which has a liquid crystal element, a light emitting diode (LED element), an organic electroluminescent (organic EL) element, etc.

Such a display is usually provided with a protective plate on the surface side of the display panel. A gap, that is, an air layer, is provided between the protective plate and the display panel so that the deformed protective plate does not come into contact with the display panel even when the protective plate is deformed due to an external force.

However, in the display as described above, there is a problem in that the light reflection loss due to the difference in refractive index between the protective panel and the air layer and the difference in the refractive index between the air layer and the display panel is large, so that the image quality of the display is deteriorated.

Accordingly, it has been proposed to improve the image quality of a display by filling the gap between the guard plate and the display panel with an adhesive to form an adhesive layer.

However, when the guard plate is provided with a frame-type printed layer on the display panel side, a level difference occurs on the surface of the guard plate on the display panel side. When the elastic modulus of an adhesive layer is too high, an adhesive layer cannot follow this level|step difference. As a result, there exists a problem in which a bubble or floatation and peeling of an adhesive layer generate|occur|produce between the pressure-sensitive adhesive layer in the vicinity of a step, and a guard plate, and impair the aesthetics as an image display apparatus. Alternatively, even if the pressure-sensitive adhesive layer can follow the level difference for a certain period (initial stage), when exposed to high temperature and high humidity conditions, bubbles or lifting and peeling of the pressure-sensitive adhesive layer occur between the pressure-sensitive adhesive layer near the level difference and the guard plate, and the image display device There is a problem that harms the aesthetics as a Hereinafter, the ability of the pressure-sensitive adhesive layer to follow the level difference in order to prevent the occurrence of bubbles between the pressure-sensitive adhesive layer and the guard plate or the lifting and peeling of the pressure-sensitive adhesive layer is simply referred to as “step difference followability”.

In order to improve such step followability, as an adhesive layer that fills the gap between the protective panel and the display module, the shear storage modulus (G') at 25°C and 1 Hz is 1.0×10 ⁵ Pa or less, and the gel fraction is 40% The above-mentioned adhesive layer is disclosed (for example, refer patent document 1).

However, in the pressure-sensitive adhesive layer (adhesive agent) of Patent Document 1, when the display is returned to normal temperature and humidity after the display is placed under durable conditions such as high temperature and high humidity, the followability to steps is inferior. That is, in the adhesive layer of patent document 1, there existed a problem that a bubble generate|occur|produced between an adhesive layer and to-be-adhered body, or transparency of an adhesive layer fell.

In order to solve such a problem, the adhesive sheet provided with the adhesive layer containing a (meth)acrylic acid ester copolymer and an active energy ray-curable component is proposed (refer patent document 2).

However, when the adhesive sheet of patent document 2 was applied to various to-be-adhered bodies used for a display, there existed a problem that adhesive force became inadequate depending on to-be-adhered bodies.

Japanese Patent Laid-Open No. 2010-97070 Japanese Patent Laid-Open No. 2014-196451

SUMMARY OF THE INVENTION It is an object of the present invention to provide an adhesive sheet having high adhesion to various adherends and excellent in foaming resistance (blister resistance) and step followability.

This object is achieved by the present invention of the following (1) to (7).

(1) (meth)acrylic acid ester polymer containing, as monomer units constituting the polymer, a monomer having an alicyclic structure and a monomer having a nitrogen atom; and

An active energy ray-curable component; a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive composition.

(2) The (meth)acrylic acid ester polymer contains 3% by mass or more and 20% by mass or less of the monomer having an alicyclic structure as the monomer unit constituting the polymer, and 1% by mass of the monomer having a nitrogen atom. The adhesive sheet as described in said (1) containing 20 mass % or less more.

(3) The (meth)acrylic acid ester polymer contains, as the monomer unit constituting the polymer, 5% by mass or more and 40% by mass or less of the monomer having an alicyclic structure and the monomer having a nitrogen atom in total ( The pressure-sensitive adhesive sheet according to 1) or (2).

(4) The pressure-sensitive adhesive sheet according to any one of (1) to (3), wherein the alicyclic structure includes an isobornyl skeleton.

(5) The pressure-sensitive adhesive sheet according to any one of (1) to (4), wherein the nitrogen atom-containing monomer has a nitrogen-containing heterocycle.

(6) The adhesive sheet in any one of said (1)-(5) which contains 0.1 mass part or more and 30 mass parts or less of the said active energy ray-curable component with respect to 100 mass parts of said (meth)acrylic acid ester polymers.

(7) The adhesive sheet in any one of said (1)-(6) used in order to bond a guard plate and a display panel together.

ADVANTAGE OF THE INVENTION According to this invention, it has high adhesive force with respect to various to-be-adhered bodies (especially a transparent conductive film or glass), and it can provide the adhesive sheet excellent in foaming resistance (blister performance) and step|step difference tracking property.

1 is a cross-sectional view showing an example of a display in which a protective plate and a display panel are bonded using the adhesive sheet of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on preferable embodiment.

<1> Adhesive composition

The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive sheet of the present embodiment is a (meth)acrylic acid ester polymer comprising, as monomer units constituting the polymer, a monomer having an alicyclic structure and a monomer having a nitrogen atom; and an active energy ray-curable component.

The pressure-sensitive adhesive sheet of this embodiment composed of the pressure-sensitive adhesive composition having the above characteristics is a cured product of the pressure-sensitive adhesive sheet obtained by being irradiated with active energy rays after being attached to various adherends (especially ITO or glass) (hereinafter, “adhesive after curing”). sheet") has high adhesion. Further, even when there is a step difference in the bonding surface of the adherend, the pressure-sensitive adhesive sheet of the present embodiment can easily follow the step difference. In addition, when an adhesive sheet after curing is formed by irradiating an active energy ray to the adhesive sheet, even after the adhesive sheet after curing is stored under durable (high temperature, high humidity) conditions, there are voids or air bubbles between the bonding surface of the adherend and the cured adhesive sheet. can be prevented from occurring. That is, the adhesive sheet of this embodiment and its hardened|cured material have the outstanding step|step difference followability|trackability. In the case of an adherend, such as a plastic plate having a problem with blistering properties under durable conditions, even if the adherend and the cured adhesive sheet are exposed to durable conditions, the plastic plate, etc., at the interface between the adherend and the cured adhesive sheet It is possible to effectively prevent the generation of bubbles from the adherend. That is, the adhesive sheet after curing has excellent blister resistance.

Hereinafter, each component constituting the pressure-sensitive adhesive composition will be described in detail.

1. (meth)acrylic acid ester polymer

The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive sheet contains a (meth)acrylic acid ester polymer.

In the present embodiment, the (meth)acrylic acid ester polymer is a monomer unit constituting the polymer, and includes a monomer having an alicyclic structure (hereinafter simply referred to as an “alicyclic structure-containing monomer”) and a monomer having a nitrogen atom (hereinafter simply referred to as “a monomer containing an alicyclic structure”). Also called "nitrogen atom-containing monomer"). In addition, in this specification, (meth)acrylic acid ester means both an acrylic acid ester and a methacrylic acid ester. The same is true for other similar terms. Also included in "polymer" is the concept of "copolymer".

Since the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive sheet includes the (meth)acrylic acid ester polymer, the pressure-sensitive adhesive sheet is formed after irradiation with active energy rays, a transparent conductive film (especially a transparent conductive film made of tin-doped indium oxide (ITO)), glass and plastic It exhibits strong adhesive force with respect to various to-be-adhered bodies used for displays, such as (especially plastics, such as polycarbonate and polymethyl methacrylate). In other words, the adhesive sheet after curing exhibits a strong adhesive force to various adherends used in displays.

On the other hand, it is thought that an alicyclic structure containing monomer mainly contributes to the adhesive force with respect to the transparent conductive film of an adhesive sheet. Further, it is considered that the nitrogen atom-containing monomer mainly contributes to the adhesive force of the pressure-sensitive adhesive sheet to glass and plastic. In addition, by increasing the volume of the alicyclic structure-containing monomer, it is possible to widen the space between the polymers and provide an adhesive sheet having excellent flexibility. Thereby, the adhesive sheet can improve the followability|trackability with respect to the unevenness|corrugation of the surface of a to-be-adhered body. Further, the nitrogen atom-containing monomer imparts a predetermined polarity to the pressure-sensitive adhesive composition. Thereby, it is possible to provide an adhesive sheet having excellent affinity to an adherend having a certain degree of polarity, such as a transparent conductive film or glass. As a result, it is estimated that the said followability|trackability and the said affinity properties harmonize and the adhesive sheet can exhibit the outstanding adhesive force also to a transparent conductive film and glass after active energy ray irradiation.

In the alicyclic structure-containing monomer, the carbocyclic ring of the alicyclic structure may have a saturated structure or may have an unsaturated bond. Further, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as bicyclic or tricyclic structure. It is preferable that carbon number of an alicyclic structure is 5 or more, It is more preferable that it is 6 or more, It is more preferable that it is 7 or more. Moreover, it is preferable that carbon number of an alicyclic structure is 20 or less, It is more preferable that it is 15 or less, It is still more preferable that it is 12 or less.

Examples of the alicyclic structure include cyclohexyl skeleton, dicyclopentadiene skeleton, adamantane skeleton, isobornyl skeleton, cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, cyclodecane skeleton, cycloundecane skeleton, cyclododecane skeleton, etc.), cycloalkene skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornadiene skeleton, polycyclic skeleton (cubane skeleton, basketane skeleton, Hausein skeleton etc.), the structure containing a spiro skeleton, etc. are mentioned. Especially, it is preferable to include the isobornyl skeleton which exhibits the more outstanding adhesive force.

As the alicyclic structure-containing monomer, a (meth)acrylic acid ester monomer having the above skeleton is preferable, and specifically, (meth)acrylic acid cyclohexyl, (meth)acrylic acid dicyclopentanyl, (meth)acrylic acid adamantyl , (meth)acrylic acid isobornyl, (meth)acrylic acid dicyclopentenyl, (meth)acrylic acid dicyclopentenyloxyethyl, etc. are mentioned. It can be used 1 type or in combination of 2 or more types among these. Among these, it is preferable to use (meth)acrylic acid isobornyl which exhibits more outstanding adhesive force.

The (meth)acrylic acid ester polymer, as a monomer unit constituting the polymer, preferably contains 3% by mass or more of the alicyclic structure-containing monomer, more preferably 6% by mass or more, and contains 9% by mass or more more preferably. Thereby, the adhesive sheet obtained can fully exhibit the outstanding adhesive force with respect to a transparent conductive film, glass, and plastic (especially excellent adhesive force with respect to a transparent conductive film) after active energy ray irradiation. In addition, the (meth)acrylic acid ester polymer, as a monomer unit constituting the polymer, preferably contains 20% by mass or less of an alicyclic structure-containing monomer, more preferably 18% by mass or less, and contains 15% by mass or less more preferably. Thereby, in a (meth)acrylic acid ester polymer, content of another monomer component can fully be ensured. As a result, the adhesive sheet can fully exhibit the outstanding adhesive force after active energy ray irradiation.

Examples of the nitrogen atom-containing monomer contained in the (meth)acrylic acid ester polymer as a monomer unit constituting the polymer include a monomer having an amino group, a monomer having an amide group, a monomer having a nitrogen-containing heterocycle, and the like. . Among these, the monomer which has a nitrogen-containing heterocyclic ring is preferable.

Examples of the monomer having a nitrogen-containing heterocycle include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth) Acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl(meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2- Vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. are mentioned. Among these, N-(meth)acryloylmorpholine which exhibits more outstanding adhesive force is preferable, and N-acryloylmorpholine is especially preferable.

On the other hand, as the nitrogen atom-containing monomer, for example, (meth)acrylamide, N-methyl (meth)acrylamide, N-methylol (meth)acrylamide, N-tert-butyl (meth)acrylamide, N,N -Dimethyl (meth)acrylamide, N,N-ethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-phenyl (meth)acrylamide , dimethylaminopropyl (meth)acrylamide, N-vinylcaprolactam, (meth)acrylic acid monomethylaminoethyl, (meth)acrylic acid monoethylaminoethyl, (meth)acrylic acid monomethylaminopropyl, (meth)acrylic acid monoethylamino Propyl, dimethylaminoethyl (meth)acrylate, etc. can also be used.

The above nitrogen atom containing monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

The (meth)acrylic acid ester polymer, as a monomer unit constituting the polymer, preferably contains 1 mass % or more of a nitrogen atom-containing monomer, more preferably 3 mass % or more, and further contains 5 mass % or more desirable. Thereby, the adhesive sheet obtained can fully exhibit the outstanding adhesive force with respect to a transparent conductive film and glass and plastics (especially the outstanding adhesive force with respect to glass and plastics) after active energy ray irradiation. Further, the (meth)acrylic acid ester polymer, as a monomer unit constituting the polymer, preferably contains 20% by mass or less of a nitrogen atom-containing monomer, more preferably 15% by mass or less, and contains 10% by mass or less more preferably. Thereby, in the (meth)acrylic acid ester polymer, content of another monomer component can fully be ensured and it can suppress that the (meth)acrylic acid ester polymer becomes too hard. As a result, the obtained adhesive sheet can fully exhibit the outstanding adhesive force after active energy ray irradiation.

(meth)acrylic acid ester polymer, as a monomer unit constituting the polymer, preferably contains 5% by mass or more in total of the alicyclic structure-containing monomer and the nitrogen atom-containing monomer, more preferably 10% by mass or more in total, It is more preferable to contain 15 mass % or more in total. Thereby, the adhesive sheet after curing formed by irradiating the adhesive sheet with active energy rays can sufficiently exhibit excellent adhesion to the transparent conductive film and glass and plastic. Further, the (meth)acrylic acid ester polymer preferably contains 40% by mass or less in total of the alicyclic structure-containing monomer and the nitrogen atom-containing monomer as a monomer unit constituting the polymer, and more preferably 35% by mass or less in total. , it is more preferable to contain 30 mass % or less in total. Thereby, it can suppress that the (meth)acrylic acid ester polymer becomes hard too much. As a result, the adhesive sheet can fully exhibit the outstanding adhesive force after active energy ray irradiation.

Moreover, the (meth)acrylic acid ester polymer may contain monomers other than the said alicyclic structure containing monomer and a nitrogen atom containing monomer as a structural unit.

As such a monomer, it is preferable to use a (meth)acrylic-acid alkylester, and it is more preferable to use the (meth)acrylic-acid alkylester whose carbon number of an alkyl group is 1 or more and 20 or less. Thereby, the adhesive sheet which has favorable adhesiveness can be provided.

In addition, the (meth)acrylic acid ester polymer preferably contains (meth)acrylic acid alkylester having 1 to 20 carbon atoms in the alkyl group as a main component (the largest component among monomers constituting the polymer).

Examples of the (meth)acrylic acid alkyl ester having an alkyl group having 1 or more and 20 or less carbon atoms include methyl acrylate, ethyl (meth)acrylate, propyl (meth)acrylic acid, n-butyl (meth)acrylate, and n-pentyl (meth)acrylic acid. , (meth)acrylic acid n-hexyl, (meth)acrylic acid 2-ethylhexyl, (meth)acrylic acid isooctyl, (meth)acrylic acid n-decyl, (meth)acrylic acid n-dodecyl, (meth)acrylic acid myristyl, ( and palmityl (meth)acrylate and stearyl (meth)acrylate. Among them, (meth)acrylic acid ester having 1 to 8 carbon atoms in the alkyl group is preferable, and n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are particularly preferable from the viewpoint of further improving the adhesiveness. In addition, these may be used independently and may be used in combination of 2 or more type.

(meth)acrylic acid ester polymer, as a monomer unit constituting the polymer, preferably contains 50 mass% or more of (meth)acrylic acid alkylester, more preferably contains 55 mass% or more, and contains 60 mass% or more more preferably. In addition, the (meth)acrylic acid ester polymer preferably contains 95% by mass or less of (meth)acrylic acid alkylester as a monomer unit constituting the polymer, more preferably 90% by mass or less, and contains 80% by mass or less more preferably.

When the pressure-sensitive adhesive composition contains a crosslinking agent described later, the (meth)acrylic acid ester polymer preferably contains a reactive functional group-containing monomer having a functional group capable of reacting with the crosslinking agent as a monomer unit constituting the polymer.

As said reactive functional group containing monomer, the monomer which has a hydroxyl group in a molecule|numerator (hydroxyl group containing monomer), the monomer which has a carboxyl group in a molecule|numerator (carboxyl group containing monomer), etc. are mentioned. However, the (meth)acrylic acid ester polymer preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Thereby, it can suppress that the adhesive sheet obtained corrodes the transparent conductive film which is an adherend, or changes the resistance value of a transparent conductive film.

Here, "not containing a carboxyl group-containing monomer" means substantially not containing a carboxyl group-containing monomer, and not only does not contain any carboxyl group-containing monomer, but also contains a carboxyl group to such an extent that corrosion of the transparent conductive film by a carboxyl group does not occur. It means to allow the containing monomers to be contained. Specifically, in the (meth)acrylic acid ester polymer, it is allowed to contain, as a monomer unit, a carboxyl group-containing monomer in an amount of 1.0 mass % or less, preferably 0.5 mass % or less.

For the above reasons, the (meth)acrylic acid ester polymer preferably contains a hydroxyl group-containing monomer as the reactive functional group-containing monomer constituting the polymer.

As the hydroxyl group-containing monomer, for example, (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 2-hydroxybutyl, ( (meth)acrylic acid hydroxyalkyl esters, such as meth)acrylic-acid 3-hydroxybutyl and (meth)acrylic-acid 4-hydroxybutyl, etc. are mentioned. Among these, 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate is preferable from the viewpoint of reactivity with a crosslinking agent and copolymerizability with other monomers. These may be used independently and may be used in combination of 2 or more type.

The (meth)acrylic acid ester polymer, as a monomer unit constituting the polymer, preferably contains 5 mass % or more of a reactive functional group-containing monomer, more preferably 10 mass % or more, and further contains 15 mass % or more desirable. Further, the (meth)acrylic acid ester polymer, as a monomer unit constituting the polymer, preferably contains 30% by mass or less of a reactive functional group-containing monomer, more preferably 25% by mass or less, and contains 20% by mass or less more preferably.

The (meth)acrylic acid ester polymer may contain other monomers other than the above as a monomer unit constituting the polymer. As said other monomer, (meth)acrylic-acid alkoxyalkyl esters, such as (meth)acrylic-acid methoxyethyl and (meth)acrylic-acid ethoxyethyl, vinyl acetate, styrene, etc. are mentioned, for example. These may be used independently and may be used in combination of 2 or more type.

A random copolymer may be sufficient as the polymerization form of a (meth)acrylic acid ester polymer, and a block copolymer may be sufficient as it.

It is preferable that the weight average molecular weight of a (meth)acrylic acid ester polymer is 300,000 or more, It is more preferable that it is 400,000 or more, It is still more preferable that it is 500,000 or more. Further, the weight average molecular weight of the (meth)acrylic acid ester polymer is preferably 1,200,000 or less, more preferably 1,000,000 or less, still more preferably 700,000 or less. Meanwhile, the weight average molecular weight in the present specification is a standard polystyrene conversion value measured by gel permeation chromatography (GPC).

In addition, in an adhesive composition, the (meth)acrylic acid ester polymer may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, the adhesive composition may further contain the (meth)acrylic acid ester polymer which does not contain an alicyclic structure containing monomer and/or a nitrogen atom containing monomer as a structural monomer unit.

In addition, from the viewpoint of sufficiently exhibiting the effect of the pressure-sensitive adhesive sheet of the present embodiment, the (meth)acrylic acid ester polymer is preferably contained in an amount of 50% by mass or more in the pressure-sensitive adhesive composition (excluding polymerization solvents and dilution solvents described later), 60 It is more preferable to contain by mass % or more, and it is especially preferable to contain 70 mass % or more. In addition, from the viewpoint of allowing the pressure-sensitive adhesive composition to contain other components, the (meth)acrylic acid ester polymer is preferably contained in an amount of 99% by mass or less in the pressure-sensitive adhesive composition, preferably 98% by mass or less, and contains 97% by mass or less. It is particularly preferred.

2. Active energy ray-curable component

The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive sheet contains an active energy ray-curable component.

As described above, the pressure-sensitive adhesive sheet composed of the pressure-sensitive adhesive composition containing the active energy ray-curable component exhibits excellent step tracking properties and excellent foaming resistance (blister resistance) by curing by irradiating active energy rays after bonding to an adherend. That is, the pressure-sensitive adhesive sheet after curing has excellent step followability and foaming resistance (blister resistance).

Here, an active energy ray has an energy proton among an electromagnetic wave or a charged particle beam, Specifically, an ultraviolet-ray, an electron beam, etc. are mentioned. Among active energy rays, an easy-to-handle ultraviolet-ray is particularly preferable.

An active energy ray-curable component will not restrict|limit especially if it is a component which does not interfere with the effect of this invention, and is hardened by irradiation of an active energy ray. Moreover, any of a monomer, an oligomer, or a polymer may be sufficient as an active energy ray-curable component, and those mixtures may be sufficient as it. Among them, as the active energy ray-curable component, a polyfunctional acrylate-based monomer having a molecular weight of less than 1000 excellent in compatibility with the above-described (meth)acrylic acid ester polymer and the like can be preferably used.

Examples of the polyfunctional acrylate monomer having a molecular weight of less than 1000 include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate. , Polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dish Clopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, di(acryloxyethyl)isocyanurate, allylated cyclohexyldi(meth)acrylate, ethoxylated bisphenol A diacrylate bifunctional types such as , 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene; Trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane tri( trifunctional types such as meth)acrylate, tris(acryloxyethyl)isocyanurate, and ε-caprolactone-modified tris(2-(meth)acryloxyethyl)isocyanurate; tetrafunctional types such as diglycerin tetra(meth)acrylate and pentaerythritol tetra(meth)acrylate; 5 functional types, such as propionic acid modified dipentaerythritol penta (meth)acrylate; Acrylate-type monomers, such as 6 functional types, such as dipentaerythritol hexa (meth)acrylate and caprolactone modified|denatured dipentaerythritol hexa (meth)acrylate, are mentioned. These may be used individually by 1 type, or may be used in combination of 2 or more type. On the other hand, from the viewpoint of further improving the blister resistance and step followability of the pressure-sensitive adhesive sheet after curing by irradiation with active energy rays, the polyfunctional acrylate-based monomer is preferably trifunctional or more, and the entire polyfunctional acrylate-based monomer is The ratio of the trifunctional or higher acrylate monomer is preferably 50 mass % or more, more preferably 70 mass % or more, and particularly preferably 90 mass % or more. In addition, the upper limit of the said ratio is 100 mass %.

As the active energy ray-curable component, an active energy ray-curable acrylate-based oligomer can also be used. It is preferable that the weight average molecular weight of this acrylate-type oligomer is 50,000 or less. Examples of such acrylate oligomers include oligomers such as polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and silicone acrylate.

The weight average molecular weight of the acrylate-based oligomer is preferably 50,000 or less, and more preferably 40,000 or less. In addition, the weight average molecular weight of the acrylate-based oligomer is more preferably 500 or more, more preferably 3,000 or more. These acrylate-type oligomers may be used individually by 1 type, and may be used in combination of 2 or more type.

Moreover, as an active energy ray-curable component, the adduct acrylate type polymer in which the group which has a (meth)acryloyl group was introduce|transduced into the side chain can also be used. Such an adduct acrylate polymer can be obtained using a copolymer of (meth)acrylic acid ester and a monomer having a crosslinkable functional group in the molecule. Specifically, an adduct acrylate-based polymer can be obtained by reacting a compound having a (meth)acryloyl group and a group reactive with a crosslinkable functional group with some of the crosslinkable functional groups of the copolymer.

The weight average molecular weight of the adduct acrylate-based polymer is preferably 50,000 or more, and more preferably 100,000 or more. Moreover, it is preferable that it is 900,000 or less, and, as for the weight average molecular weight of an adduct acrylate-type polymer, it is more preferable that it is 500,000 or less.

The active energy ray-curable component may be used by selecting one type from among the aforementioned polyfunctional acrylate-based monomers, acrylate-based oligomers and adduct acrylate-based polymers, or may be used in combination of two or more types, It can also be used in combination with an energy ray-curable component.

It is preferable that content of the active energy ray-curable component in an adhesive composition is 0.1 mass part or more with respect to 100 mass parts of (meth)acrylic acid ester polymers, It is more preferable that it is 0.5 mass part or more, It is still more preferable that it is 1 mass part or more. In addition, the content of the active energy ray-curable component is preferably 30 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic acid ester polymer, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, and less than 10 parts by mass It is particularly preferred.

3. Crosslinking agent

The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive sheet may contain a crosslinking agent.

When the pressure-sensitive adhesive composition contains a crosslinking agent and a (meth)acrylic acid ester polymer having a reactive functional group-containing monomer, the crosslinking agent reacts with a reactive functional group derived from a reactive functional group-containing monomer constituting the (meth)acrylic acid ester polymer. Thereby, the (meth)acrylic acid ester polymer which has a crosslinked structure is formed. As a result, the cohesive force of an adhesive sheet improves.

The crosslinking agent is not particularly limited as long as it reacts with the reactive functional group of the (meth)acrylic acid ester polymer, for example, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an amine-based crosslinking agent, a melamine-based crosslinking agent, an aziridine-based crosslinking agent, a hydrazine-based crosslinking agent, an aldehyde-based crosslinking agent , an oxazoline-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, and an ammonium salt-based crosslinking agent. When the (meth)acrylic acid ester polymer has a hydroxyl group as a reactive functional group, it is preferable to use an isocyanate-based crosslinking agent excellent in reactivity with a hydroxyl group among the above. In addition, a crosslinking agent can be used individually by 1 type or in combination of 2 or more type.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound.

As a polyisocyanate compound, For example, aromatic polyisocyanate, such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, aliphatic polyisocyanate, such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane di Alicyclic polyisocyanates such as isocyanates, etc., and their biuret forms, isocyanurate forms, and further reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil A duct body etc. are mentioned. When the (meth)acrylic acid ester polymer has a hydroxyl group as a reactive functional group, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate, is preferable from the viewpoint of reactivity with a hydroxyl group.

The content of the crosslinking agent in the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive sheet is preferably 0.05 parts by mass or more, more preferably 0.10 parts by mass or more, still more preferably 0.15 parts by mass or more with respect to 100 parts by mass of the (meth)acrylic acid ester polymer. Moreover, it is preferable that content of a crosslinking agent in an adhesive composition is 3.00 mass parts or less, It is more preferable that it is 2.00 mass parts or less, It is still more preferable that it is 1.00 mass parts or less.

4. Photoinitiator

The adhesive composition which comprises the adhesive sheet of this embodiment may also contain a photoinitiator. When an adhesive composition contains a photoinitiator, an adhesive sheet hardens|cures efficiently. For example, a protective plate having a step difference and a display panel are bonded to each other with an adhesive sheet interposed therebetween so that the step difference faces the display panel. Thereafter, the adhesive sheet is irradiated with active energy rays to form a cured adhesive sheet. In this case, the pressure-sensitive adhesive sheet is efficiently cured, and the pressure-sensitive adhesive sheet after curing has excellent blister resistance and excellent followability to steps. As a result, the image display apparatus obtained exhibits outstanding durability.

The photopolymerization initiator is not particularly limited as long as it is a commonly used photopolymerization initiator, and for example, benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, Benzoinbenzoic acid, methylbenzoinbenzoate, benzoindimethylketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexylphenylketone, benzyldiphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyro Nitrile, benzyl, dibenzyl, diacetyl, β-chloroanthraquinone, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, (2,4,6-trimethylbenzyldi Phenyl) phosphine oxide, 2-benzothiazole-N,N-diethyldithiocarbamate, etc. can be used. In addition, a photoinitiator may be used individually by 1 type, and may use 2 or more types together.

Moreover, it is preferable to contain 0.1 mass part or more with respect to 100 mass parts of active energy ray-curable components, and, as for a photoinitiator, it is more preferable to contain 1 mass part or more. Moreover, it is preferable to contain 30 mass parts or less with respect to 100 mass parts of active energy ray-curable components, and, as for a photoinitiator, it is more preferable to contain 15 mass parts or less.

5. Other ingredients

In the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive sheet, if necessary, various additives commonly used in acrylic pressure-sensitive adhesives, for example, a silane coupling agent, an antistatic agent, a tackifier, an antioxidant, an ultraviolet absorber, a light stabilizer, a softener, a filler, a refractive index adjuster etc. can be added.

<2> Preparation of pressure-sensitive adhesive composition

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive sheet is prepared by preparing a (meth)acrylic acid ester polymer, mixing the obtained (meth)acrylic acid ester polymer with an active energy ray-curable component, and optionally adding a crosslinking agent, a photopolymerization initiator and other additives It can be manufactured by

The (meth)acrylic acid ester polymer can be produced by polymerization of a mixture of monomers constituting the polymer by a conventional radical polymerization method.

Polymerization of the monomer constituting the (meth)acrylic acid ester polymer can be carried out by a solution polymerization method or the like using a polymerization initiator if desired. As a polymerization solvent, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone etc. are mentioned, for example, You may use 2 or more types together.

As a polymerization initiator, an azo-type compound, an organic peroxide, etc. are mentioned, You may use 2 or more types together. As the azo compound, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobeads (2-methylbutyronitrile), 1,1'-azobeads (cyclohexane1-carbononi Trill), 2,2'-azobeads (2,4-dimethylvaleronitrile), 2,2'-azobeads (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'- Azo beads (2-methylpropionate), 4,4'-azo beads (4-cyanovaleric acid), 2,2'-azo beads (2-hydroxymethyl propionitrile), 2,2'- azobis[2-(2-imidazolin-2-yl)propane] etc. are mentioned.

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di(2-ethoxyethyl)peroxydicarbonate. carbonate, t-butylperoxyneodecanoate, t-butylperoxypivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionylperoxide, diacetylperoxide, and the like.

On the other hand, by blending a chain transfer agent such as 2-mercaptoethanol in the polymerization step, the weight average molecular weight of the obtained polymer can be adjusted.

After the (meth)acrylic acid ester polymer is obtained, an active energy ray-curable component and, if desired, a crosslinking agent, a photoinitiator and other additives are added to a solution of the (meth)acrylic acid ester polymer and sufficiently mixed to obtain a pressure-sensitive adhesive composition. Meanwhile, the pressure-sensitive adhesive composition may be diluted with a desired dilution solvent. As the dilution solvent, the polymerization solvent described above may be used.

<3> Manufacture of adhesive sheet

An adhesive sheet is obtained by bridge|crosslinking the (meth)acrylic acid ester polymer in the above-mentioned adhesive composition.

An adhesive sheet can be manufactured as follows, for example.

First, a release sheet is prepared.

Next, the pressure-sensitive adhesive composition (coating solution) is applied to the release surface of the release sheet to form an application layer.

And an adhesive sheet (adhesive sheet of this invention) is obtained by heat-processing with respect to an application layer and bridge|crosslinking the (meth)acrylic acid ester polymer in an adhesive composition.

On the other hand, you may superimpose the peeling surface of another peeling sheet on the exposed adhesive surface of an adhesive sheet as needed.

As a method of applying the coating liquid of the pressure-sensitive adhesive composition, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used.

In addition, crosslinking of the (meth)acrylic acid ester polymer in an adhesive composition can be performed by heat processing. This heat treatment can also be performed as a drying process of an application layer after application|coating of an adhesive composition. It is preferable that it is 50 degreeC or more, and, as for the heating temperature of heat processing, it is more preferable that it is 70 degreeC or more. Moreover, it is preferable that it is 150 degrees C or less, and, as for the heating temperature of heat processing, it is more preferable that it is 120 degrees C or less. Moreover, it is preferable that it is 10 second or more, and, as for heating time, it is more preferable that it is 50 second or more. Moreover, it is preferable that it is 10 minutes or less, and, as for a heating time, it is more preferable that it is 2 minutes or less.

The thickness (value measured according to JIS K7130) of the pressure-sensitive adhesive sheet obtained as described above is preferably 10 µm or more, more preferably 30 µm or more, and still more preferably 50 µm or more from the viewpoint of obtaining excellent step difference followability. Moreover, it is preferable that it is 1000 micrometers or less from a viewpoint of ensuring the workability of an adhesive sheet, as for the thickness of an adhesive sheet, it is more preferable that it is 400 micrometers or less, It is still more preferable that it is 300 micrometers or less. In addition, the pressure-sensitive adhesive sheet may be formed in a single layer, or may be formed by laminating a plurality of layers.

In addition, the adhesive sheet can also be manufactured as follows.

First, two release sheets are prepared.

The pressure-sensitive adhesive composition (coating solution) is applied to the release surface of one of the prepared release sheets to form an application layer. The coating layer is heat-treated to crosslink the (meth)acrylic acid ester polymer in the pressure-sensitive adhesive composition to form a first pressure-sensitive adhesive sheet. Further, the pressure-sensitive adhesive composition (coating solution) is applied to the release surface of the other release sheet to form an application layer. The coating layer is heat-treated to crosslink the (meth)acrylic acid ester polymer in the pressure-sensitive adhesive composition to form a second pressure-sensitive adhesive sheet. And it bonds so that the exposed adhesive surfaces of the said two adhesive sheets may mutually contact, and a 3rd adhesive sheet (adhesive sheet of this invention) is obtained. Accordingly, the third pressure-sensitive adhesive sheet has a thickness that is the sum of the thickness of the first pressure-sensitive adhesive sheet and the thickness of the second pressure-sensitive adhesive sheet.

The method of apply|coating the coating liquid of the said adhesive composition, and the heat processing conditions with respect to the apply|coated adhesive composition are as above-mentioned.

<4> Display (image display device)

1 is a cross-sectional view showing an example of a display in which a protective plate and a display panel are bonded using the adhesive sheet of the present invention. Meanwhile, in the following description, the upper side of the drawing is referred to as "above" or "upper", and the lower side is referred to as "below" or "below".

The display (image display device) 100 includes a protective plate 21 ; display panel 22; and the cured adhesive sheet 11 (the adhesive sheet of the present invention) obtained by irradiation with active energy rays.

As shown in FIG. 1 , the guard plate 21 has a step (printed layer) 3 on the side in contact with the pressure-sensitive adhesive sheet 11 after curing. Moreover, it is preferable that the height of this level|step difference 3 is 3 micrometers or more and 45 micrometers or less. Even when the guard plate 21 has such a step 3, the pressure-sensitive adhesive sheet of the present invention follows the step 3 favorably. Then, the adhesive sheet 11 is formed after curing by irradiating the adhesive sheet with an active energy ray from either or both surface sides of the guard plate 21 or the display panel 22 . After such curing, the pressure-sensitive adhesive sheet 11 can sufficiently exhibit high adhesive strength, blister resistance, and step followability.

On the other hand, as mentioned above, an active energy ray has an energy proton among an electromagnetic wave or a charged particle beam, For example, an ultraviolet-ray, an electron beam, etc. are mentioned. From a viewpoint of handling easiness, an ultraviolet-ray is preferable.

Irradiation of ultraviolet rays can be performed by a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, or the like. It is preferable that the irradiation amount of ultraviolet rays is about 50-1000 mW/cm<2> of illuminance. Moreover, it is preferable that the amount of light is 50-10000 mJ/cm<2>, It is more preferable that it is 100-5000 mJ/cm<2> It is especially preferable that it is 200-1500 mJ/cm<2>.

As the display 100, a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescent (organic EL) display, electronic paper etc. are mentioned, for example, A touch panel may be sufficient.

It is preferable that the guard plate 21 is comprised from a glass plate, a plastic plate, etc., and the laminated body etc. which contain them. In this case, it is common to form the frame-type printing layer 3 on the surface on the side of the pressure-sensitive adhesive sheet 11 after curing of the guard plate 21 .

The display panel 22 is a display module (eg, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, etc.) or a part thereof (eg, an optical member such as a polarizing plate) It is preferable to be

The glass plate is not particularly limited, and for example, chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, etc. can be heard Although the thickness of a glass plate is not specifically limited, Usually, it is 0.1-5 mm, Preferably it is 0.2-2 mm.

It does not specifically limit as said plastic plate, For example, an acrylic plate, a polycarbonate plate, etc. are mentioned. Although the thickness of a plastic plate is not specifically limited, Usually, it is 0.2-5 mm, Preferably it is 0.4-3 mm.

On the other hand, various functional layers (a transparent conductive film, a metal layer, a silica layer, a hard coat layer, an anti-glare layer, etc.) may be provided on one side or both surfaces of the said glass plate or a plastic plate, and an optical member may be laminated|stacked. Moreover, the transparent conductive film and the metal layer may be patterned.

As the optical member, for example, a polarizing plate (polarizing film), a polarizer, a retardation plate (retardation film), a viewing angle compensation film, a brightness improving film, a contrast enhancing film, a liquid crystal polymer film, a diffusion film, a hard coat film, a transflective film A film etc. are mentioned.

The material constituting the printed layer 3 is not particularly limited, and a known material for printing is used. The thickness of the printed layer 3, that is, the height of the step 3 is preferably 3 µm or more and 45 µm or less, more preferably 5 µm or more and 35 µm or less, still more preferably 7 µm or more and 25 µm or less, and 7 µm or more. It is especially preferable that it is 15 micrometers or less.

In order to manufacture the display 100 , as an example, first, an adhesive sheet having release sheets on both sides is cut to sizes corresponding to the protective plate 21 and the display panel 22 .

Next, one release sheet of the pressure-sensitive adhesive sheet is peeled off, and the exposed pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet is bonded to the side surface of the guard plate 21 on which the printed layer 3 is provided. Thereafter, the other release sheet is peeled from the pressure-sensitive adhesive sheet, and the exposed pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet is bonded to the display panel 22 . Then, an active energy ray is irradiated to the adhesive sheet from the side of the guard plate 21 and/or the display panel 22, and the adhesive sheet 11 after hardening is obtained.

Since the display 100 obtained by the above process has excellent step difference followability of the adhesive sheet and the adhesive sheet 11 after curing, even after the adhesive sheet 11 is left to stand after curing under a predetermined durability condition, the printed layer 3 It is difficult to form a gap between (step 3) and the adhesive sheet 11 after curing. Therefore, the display 100 excellent in aesthetics is obtained. In addition, since the adhesive sheet and the adhesive sheet 11 after curing are excellent in adhesive strength and blister resistance, a highly reliable display 100 is obtained.

As mentioned above, although preferred embodiment of the adhesive sheet of this invention was demonstrated, this invention is not limited to this.

For example, although the guard plate has a printed layer (step difference) in the above-mentioned embodiment, the adhesive sheet of this invention is applicable also to the guard plate which does not have a printed layer (step difference).

[ Example ]

Hereinafter, the present invention will be more specifically described by way of examples and the like, but the scope of the present invention is not limited to these examples and the like.

1. Preparation of adhesive sheet

(Example 1)

(1) (meth)acrylic acid ester polymer

65 mass parts of 2-ethylhexyl acrylate, 5 mass parts of N-acryloylmorpholine, 15 mass parts of isobornyl acrylate, and 15 mass parts of acrylic acid 2-hydroxyethyl were copolymerized, and the (meth)acrylic acid ester polymer was prepared. As a result of measuring the molecular weight of this (meth)acrylic acid ester polymer by the method mentioned later, it was a weight average molecular weight (Mw) of 500,000.

(2) Preparation of pressure-sensitive adhesive composition

100 parts by mass of the (meth)acrylic acid ester polymer obtained in the step (1) (in terms of solid content; the same hereinafter) and ε-caprolactone-modified tris(2-acryloxyethyl)isocyanurate as an active energy ray-curable component [Shin-Nakamura Chemical Company, product name "NK Ester A-930-1CL") 5.0 parts by mass, and 0.15 parts by mass of trimethylolpropane-modified tolylene diisocyanate (Toyochem Corporation, product name "BHS8515") as an isocyanate-based crosslinking agent, photopolymerization 0.5 mass parts of an initiator (the product made by BASF, product name "Irgacure 500") was mixed, and it fully stirred, and obtained the liquid mixture. The adhesive composition (coating solution) of 50 mass % of solid content concentration was obtained by diluting the liquid mixture with methyl ethyl ketone.

(3) Manufacture of adhesive sheet

First, a medium release type release sheet (manufactured by Lintec, product name "SP-PET752150") obtained by peeling one side of a polyethylene terephthalate film with a silicone release agent was prepared. The adhesive composition was apply|coated to the peeling process surface with a knife coater, and the application layer was formed. And the application layer was heat-processed at 90 degreeC for 1 minute, and the 25-micrometer-thick 1st adhesive sheet was formed.

Similarly, a light-peelable release sheet (manufactured by Lintec, product name "SP-PET382120") obtained by peeling one side of a polyethylene terephthalate film with a silicone-based release agent was prepared. The adhesive composition was apply|coated to the peeling process surface with a knife coater, and the application layer was formed. And it heat-processed with respect to the application layer at 90 degreeC for 1 minute, and formed the 25-micrometer-thick 2nd adhesive sheet.

Next, the first and second pressure-sensitive adhesive sheets were bonded so that both exposed adhesive surfaces thereof were in contact with each other. For this reason, the 3rd adhesive sheet (thickness: 50 micrometers) which has a light-peelable release sheet on one surface, and a medium-peelable release sheet on the other surface was produced. In addition, the thickness of an adhesive sheet is the value measured using the static pressure thickness meter (The Techrok company make, product name "PG-02") based on JISK7130.

(Examples 2 and 3, Comparative Examples 1-3)

A third pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1, except that the ratio of each monomer constituting the (meth)acrylic acid ester polymer, the type and compounding amount of the active energy ray-curable component were changed as described in Table 1.

Table 1 shows the composition of the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive sheet of each of the above Examples and Comparative Examples.

Meanwhile, in Table 1, “2EHA” for 2-ethylhexyl acrylate, “ACMO” for N-acryloylmorpholine, “IBXA” for isobornyl acrylate, “HEA” for 2-hydroxyethyl acrylate, and methylmethacrylic acid The rate was "MMA", ε-caprolactone-modified tris(2-acryloxyethyl)isocyanurate as an active energy ray-curable component (manufactured by Shin-Nakamura Chemical, product name "NK Ester A-9300-1CL") was "3 Functional", dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical, trade name "NK Ester A-DPH") is "hexafunctional", a terpene resin as a tackifying resin (Yasuhara Chemical Co., Ltd. product, trade name "Clearon") K4100") was described as "terpene resin".

In addition, the above-mentioned weight average molecular weight (Mw) is a polystyrene conversion weight average molecular weight measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement conditions>

·GPC measuring device: Tosoh Corporation, HLC-8020

・GPC column (passed in the following order): Tosoh Corporation

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

・Measurement solvent: tetrahydrofuran

・Measurement temperature: 40℃

2. Evaluation

[Adhesive force measurement]

First, a polyethylene terephthalate film (manufactured by Toyobo, PET A4300, thickness: 100 μm) having an easily adhesive layer was prepared. Next, the light-peelable release sheet of the 3rd adhesive sheet obtained by each Example and each comparative example was peeled off, the exposed adhesive surface was bonded to the said easily adhesive layer, and the laminated body was obtained. The laminate was cut to a width of 25 mm and a length of 100 mm to prepare a sample for measuring the adhesive force. The heavy release type release sheet was peeled off from the sample, and the exposed adhesive surface was affixed to soda-lime glass (manufactured by Nippon Ita Glass). Thereafter, they were irradiated with ultraviolet rays under the following conditions.

(Ultraviolet irradiation conditions)

·Light source: high pressure mercury lamp

·Light intensity: 1000mJ/cm2

· Illuminance: 200mW/cm2

Then, the sample (adhesive sheet after hardening) was left to stand for 24 hours under the conditions of normal pressure, 23 degreeC, and 50%RH. Then, using a tensile tester (Orientec Co., Ltd., product name "Tensilon"), according to JIS Z0237:2009, the adhesive strength of the adhesive sheet after curing under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180° (N/25 mm ) was measured.

In addition, a polyethylene terephthalate film (manufactured by Oike Kogyo Co., Ltd., ITO film, thickness: 125 µm) provided with a transparent conductive film made of tin-doped indium oxide (ITO) on one side was prepared. The middle peel release sheet was removed from the sample, the exposed adhesive surface was attached to the transparent conductive film, and the adhesive force (N/25 mm) of the adhesive sheet after curing was measured in the same manner as above.

[Evaluation of blister resistance]

First, a polyethylene terephthalate film (manufactured by Oike Kogyo Co., Ltd., ITO film, thickness: 125 μm) provided with a transparent conductive film made of tin-doped indium oxide (ITO) on one side was prepared. The light-peelable release sheet of the 3rd adhesive sheet obtained by each Example and each comparative example was peeled off, the exposed adhesive surface was bonded together with the said transparent conductive film, and the laminated body was obtained. Next, the heavy release type release sheet of this laminate (adhesive sheet) is peeled off, and the exposed adhesive surface is placed on an acrylic plate made of polymethyl methacrylate (PMMA) (manufactured by Mitsubishi Gas Chemical, product name “Upiron Sheet MR200”). , thickness: 1 mm). Thereafter, they were irradiated with ultraviolet rays under the following conditions to obtain a laminate (sample) in which an ITO film and an acrylic plate were cured and bonded to an adhesive sheet.

(Ultraviolet irradiation conditions)

·Light source: high pressure mercury lamp

·Light intensity: 1000mJ/cm2

· Illuminance: 200mW/cm2

The sample was autoclaved for 30 minutes under conditions of 50°C and 0.5 MPa, and then left at normal pressure, 23°C, 50%RH for 15 hours. Then, the sample was stored for 72 hours under a durable condition of 85°C and 85%RH. After that, the sample was transferred to 23°C under 50%RH. Immediately thereafter, the presence of air bubbles or floating or peeling of the pressure-sensitive adhesive layer at the interface between the cured pressure-sensitive adhesive sheet and the acrylic plate was visually confirmed. The blister resistance of the adhesive sheet after curing was evaluated based on the following criteria.

A: There was no bubble, floating|lifting of an adhesive layer, and peeling at all.

B: Only bubbles with a diameter of 0.2 mm or less were generated.

C: Bubbles exceeding 0.2 mm in diameter and floating or peeling of the pressure-sensitive adhesive layer occurred.

[Evaluation of step trackability]

First, a glass plate (manufactured by NSG Precision Transfer, product name "Corning Glass Eagle XG," length 90 mm x width 50 mm x thickness 0.5 mm) was prepared. UV curable ink (product name "POS-911 ink", manufactured by Teikoku Ink Co., Ltd.) was screen-printed on the surface of a glass plate in a frame shape (external shape: 90 mm long × 50 mm wide, 5 mm wide) to a thickness of 25 μm. . Next, the glass plate was irradiated with ultraviolet rays (80 W/cm 2 , metal halide lamp 2 lamps, lamp height 15 cm, belt speed 10 to 15 m/min) to cure the printed ultraviolet curable ink. Thereby, the printed layer, that is, the level|step difference provision glass plate which has a level|step difference (height of a level|step difference: 25 micrometers) was produced.

Furthermore, a polyethylene terephthalate film (manufactured by Toyobo Corporation, product name "PET A4300", thickness: 100 µm) having an easily adhesive layer was prepared. The light-peelable release sheet was peeled off from the 3rd adhesive sheet obtained in each Example and each comparative example, the exposed adhesive surface was bonded to the said easily adhesive layer, and the laminated body was obtained. Next, the heavy release type release sheet of this laminate was peeled off, and the adhesive surface (pressure-sensitive adhesive layer) was exposed. Then, using a laminator (manufactured by Fujipla Corporation, product name “LPD3214”), the laminate was laminated on each step-difference glass plate so that the pressure-sensitive adhesive layer covers the entire surface of the frame-type printed layer. They were irradiated with ultraviolet rays under the following conditions to prepare a sample.

(Ultraviolet irradiation conditions)

·Light source: high pressure mercury lamp

·Light intensity: 1000mJ/cm2

· Illuminance: 200mW/cm2

The sample was stored for 72 hours under a durable condition of 85°C and 85%RH. After that, the sample was transferred to 23°C under 50%RH. Immediately thereafter, the presence of air bubbles was visually confirmed at the interface between the adhesive sheet and the glass plate after curing of the sample (particularly in the vicinity of the level difference due to printing). The followability to the step difference of the pressure-sensitive adhesive sheet after curing was evaluated based on the following criteria.

A: There were no bubbles at all.

B: Only bubbles with a diameter of 0.2 mm or less were confirmed.

C: Bubbles exceeding 0.2 mm in diameter and floating or peeling of the pressure-sensitive adhesive layer were confirmed.

[Measurement of haze value]

About the 3rd adhesive sheet obtained by the Example and the comparative example, according to JISK7361-1:1997, haze value (%) was measured using the haze meter (The Nippon Denshoku Kogyo Co., Ltd. product, product name "NDH-5000"). Considering use for a display, it is preferable that it is 2 % or less of haze value, It is more preferable that it is 1 % or less, It is especially preferable that it is 0.5 % or less.

These results are shown in Table 2.

As is evident from Table 2, the pressure-sensitive adhesive sheet (adhesive sheet after curing after UV irradiation) of each Example showed high adhesion to the transparent conductive film and glass. In addition, the adhesive sheet (adhesive sheet after curing after UV irradiation) of each Example was excellent in blister resistance and step followability. On the other hand, the adhesive sheet of each comparative example did not obtain sufficient results.

3 steps (printed layer)
11 Adhesive sheet after curing (hardened product of adhesive sheet)
21 shroud
22 display panel
100 displays

Claims (7)

As a monomer unit constituting the (meth)acrylic acid ester polymer, (meth)acrylic acid ester containing (meth)acrylic acid alkylester having 1 to 8 carbon atoms in the alkyl group, a monomer having an alicyclic structure, and a monomer having a nitrogen atom polymer; and
Including an active energy ray-curable component;
The (meth)acrylic acid ester polymer contains 50% by mass or more and 95% by mass or less of the (meth)acrylic acid alkylester as the monomer unit constituting the (meth)acrylic acid ester polymer,
With respect to 100 parts by mass of the (meth)acrylic acid ester polymer, the active energy ray-curable component is composed of a pressure-sensitive adhesive composition comprising 0.1 parts by mass or more and less than 10 parts by mass,
The said active energy ray-curable component consists of a 3- to 6-functional polyfunctional acrylate-type monomer, The said active energy ray-curable component exists in the uncured state, The adhesive sheet characterized by the above-mentioned. According to claim 1,
The (meth)acrylic acid ester polymer contains 3% by mass or more and 20% by mass or less of the monomer having an alicyclic structure as the monomer unit constituting the (meth)acrylic acid ester polymer, and contains 1 monomer having a nitrogen atom. The adhesive sheet containing 20 mass % or more and 20 mass % or less. 3. The method of claim 1 or 2,
The (meth)acrylic acid ester polymer is the monomer unit constituting the (meth)acrylic acid ester polymer, and contains 5% by mass or more and 40% by mass or less of the monomer having an alicyclic structure and the monomer having a nitrogen atom in total. Sheet. 3. The method of claim 1 or 2,
The alicyclic structure is a pressure-sensitive adhesive sheet comprising an isobornyl skeleton. 3. The method of claim 1 or 2,
The monomer having a nitrogen atom is a pressure-sensitive adhesive sheet having a nitrogen-containing heterocycle. delete 3. The method of claim 1 or 2,
An adhesive sheet used for bonding a protective plate and a display panel.

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