WO2023153152A1

WO2023153152A1 - Pressure-sensitive adhesive and pressure-sensitive adhesive sheet

Info

Publication number: WO2023153152A1
Application number: PCT/JP2023/001242
Authority: WO
Inventors: 祐七島; 翔平朝稲
Original assignee: リンテック株式会社
Priority date: 2022-02-08
Filing date: 2023-01-18
Publication date: 2023-08-17

Abstract

Provided are: a pressure-sensitive adhesive that contains an emulsion type polymer, an active energy ray-curable resin and, preferably, a photopolymerization initiator; and a pressure-sensitive adhesive sheet 1 that is constituted of a pressure-sensitive adhesive layer 11 comprising said pressure-sensitive adhesive. The emulsion type polymer is preferably an acrylic polymer, and the active energy ray-curable resin is preferably an emulsion type resin. The gel fraction in the pressure-sensitive adhesive after being cured with active energy rays is preferably 60-99%. The pressure-sensitive adhesive sheet 1 makes it possible to achieve both cohesive strength and adhesive properties.

Description

Adhesives and adhesive sheets

The present invention relates to an emulsion-based adhesive and an adhesive sheet using the adhesive.

Organic solvent-based acrylic pressure-sensitive adhesives have generally been used for pressure-sensitive adhesive layers for optical applications such as display bodies (displays) of various electronic devices. However, organic solvent type acrylic adhesives are not environmentally friendly because the organic solvent evaporates during coating. Therefore, in recent years, there has been a demand for conversion to water-based acrylic adhesives.

For example, Patent Document 1 discloses a monomer mixture containing 80% by weight or more of a (meth)acrylic acid ester, a reactive emulsifier containing a radically polymerizable functional group, and an emulsion containing a polymerization initiator. It discloses a pressure-sensitive adhesive composition for optical members containing a polymer emulsion and 0.01 to 1 part by weight of a silane coupling agent per 100 parts by weight of the solid content of the acrylic polymer emulsion.

Japanese Patent No. 4481020

Here, in the displays of smartphones and car navigation systems, a protective panel is provided on the surface side of the display module. The protective panel is usually adhered to a display module or the like via an adhesive layer. As the protective panel, a plastic plate is sometimes used from the viewpoint of weight reduction and safety.

Unlike glass plates, the above plastic plates generate outgassing and permeate water vapor under high temperature and high humidity (moist heat) conditions. As a result, blisters such as air bubbles, floating, and peeling may occur between the plastic plate and the adhesive layer. In order to suppress the occurrence of such blisters, generally, the cohesive force of the pressure-sensitive adhesive is increased.

However, adhesives that use conventional acrylic polymer emulsions have low cohesion and cannot prevent the occurrence of blisters. In order to solve this problem, it is conceivable to add a cross-linking agent to the adhesive. When a cross-linking agent is added to form a cross-linked structure, the cohesive force is increased, but the adhesion to the adherend is lowered, and blisters are still generated.

The present invention has been made in view of the actual situation as described above, and an object of the present invention is to provide a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet that can achieve both cohesion and adhesion.

In order to achieve the above object, the present invention firstly provides a pressure-sensitive adhesive containing an emulsion polymer and an active energy ray-curable resin (Invention 1).

After bonding the adherends together via the adhesive according to the above invention (Invention 1), when the adhesive is cured by irradiation with active energy rays, the cohesive force of the adhesive increases and the adherend Adhesion to is increased. That is, according to the pressure-sensitive adhesive according to the invention (invention 1), it is possible to achieve both cohesion and adhesion.

In the above invention (invention 1), the emulsion polymer is preferably an acrylic polymer (invention 2).

In the above inventions (inventions 1 and 2), the active energy ray-curable resin is preferably an emulsion resin (invention 3).

In the above inventions (inventions 1 to 3), it is preferable to contain a photopolymerization initiator (invention 4).

In the above inventions (Inventions 1 to 4), it is preferable that the gel fraction of the adhesive after curing with active energy rays is 60% or more and 99% or less (Invention 5).

In the above inventions (inventions 1 to 5), the strain amount measured after 3757 seconds of continuously applying a stress of 3000 Pa to the adhesive after active energy ray curing is 1% or more and 40% or less. Preferred (invention 6).

In the above inventions (Inventions 1 to 6), the storage elastic modulus G'(25) at 25°C of the adhesive after active energy ray curing is preferably 0.08 MPa or more and 0.40 MPa or less (Invention 7).

In the above inventions (Inventions 1 to 7), the storage elastic modulus G'(-20) at -20°C of the adhesive after active energy ray curing is preferably 0.15 MPa or more and 3.0 MPa or less. (Invention 8).

In the above inventions (Inventions 1 to 8), the storage elastic modulus G'(85) at 85°C of the adhesive after active energy ray curing is preferably 0.03 MPa or more and 0.08 MPa or less (Invention 9).

Secondly, the present invention provides a pressure-sensitive adhesive sheet comprising at least a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive (inventions 1 to 9) (invention 10 ).

In the above invention (Invention 10), it is preferable that the adhesive layer comprises two release sheets and the pressure-sensitive adhesive layer sandwiched between the two release sheets so as to be in contact with the release surfaces of the two release sheets. (Invention 11).

According to the pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention, both cohesion and adhesion can be achieved, and excellent blister resistance can be obtained.

1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention; FIG. 1 is a cross-sectional view of a construct according to an embodiment of the invention; FIG.

Embodiments of the present invention will be described below.
[Adhesive]
An adhesive according to one embodiment of the present invention (hereinafter sometimes referred to as "adhesive P") contains an emulsion polymer (A) and an active energy ray-curable resin (B), preferably Furthermore, it contains a photopolymerization initiator (C). After bonding the adherends together via such an adhesive P, the adhesive P is irradiated with an active energy ray to cure the adhesive P. As a result, the cohesive force of the adhesive P increases and Increased adhesion to the body. Therefore, even if the adherend (particularly a plastic plate) generates outgassing under high temperature and high humidity conditions, the adhesive P after curing traps the outgassing in the adherend, thereby suppressing the occurrence of blisters. That is, the pressure-sensitive adhesive P according to this embodiment exhibits excellent blister resistance.

1. Components (1) Emulsion polymer (A)
The emulsion-based polymer (A) is a main adhesive agent of the adhesive P, and is a polymer obtained by emulsion polymerization (emulsion polymerization). Examples of the type of polymer for the emulsion polymer (A) include acrylic polymers, rubber polymers, urethane polymers, and the like. Preferably. In this specification, the term "polymer" also includes the concept of "copolymer".

The emulsion-based acrylic polymer can be obtained by a conventional method. Specifically, an emulsion containing one or more acrylic monomers, an emulsifier, and a polymerization initiator is emulsified by radical polymerization. It can be obtained by polymerization.

As acrylic monomers, (meth)acrylic acid alkyl esters are preferred. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Alkyl groups may be straight or branched.

The (meth)acrylic acid alkyl ester is preferably a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms from the viewpoint of adhesiveness. Examples of (meth)acrylic acid alkyl esters having an alkyl group of 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-(meth)acrylate, Butyl, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, (meth)acrylic acid Examples include n-dodecyl, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate.

Among the above, from the viewpoint of efficiently imparting adhesive strength, (meth)acrylic acid alkyl esters having an alkyl group having a carbon number of 2 to 12 are more preferable, and acrylic acid alkyl esters having an alkyl group having a carbon number of 1 to 10 are preferable. is particularly preferred. Specifically, methyl (meth)acrylate, n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred, and 2-ethylhexyl acrylate is more preferred. These may be used alone or in combination of two or more.

As the (meth)acrylic acid alkyl ester, a monomer having a glass transition temperature (Tg) exceeding 0 ° C. as a homopolymer (hereinafter sometimes referred to as "high Tg alkyl acrylate"), other (meth)acrylic acid A combined use with an alkyl ester is preferred. Thereby, a desired cohesive force can be imparted to the pressure-sensitive adhesive to be obtained.

Examples of the high Tg alkyl acrylates include methyl acrylate (Tg 10°C), methyl methacrylate (Tg 105°C), ethyl methacrylate (Tg 65°C), n-butyl methacrylate (Tg 20°C), and isobutyl methacrylate (Tg 48°C). ), t-butyl methacrylate (Tg 107° C.), n-stearyl acrylate (Tg 30° C.), n-stearyl methacrylate (Tg 38° C.) and the like, preferably methyl methacrylate.

The (meth)acrylic acid alkyl ester is preferably contained in an amount of 80.0% by mass or more, more preferably 85.0% by mass or more, particularly 90.0% by mass, as a monomer unit constituting the acrylic polymer. % or more, more preferably 95.0 mass % or more. Further, it is preferably contained in an amount of 99.9% by mass or less, more preferably 99.5% by mass or less, particularly preferably 99.0% by mass or less, and further preferably 98.0% by mass or less. is preferred.

The high Tg alkyl acrylate is preferably contained in an amount of 1.0% by mass or more, more preferably 3.0% by mass or more, particularly 5.0% by mass or more, as a monomer unit constituting the acrylic polymer. It is preferably contained, more preferably 10.0% by mass or more. In addition, it is preferably contained in an amount of 30.0% by mass or less, more preferably 28.0% by mass or less, particularly preferably 25.0% by mass or less, and further preferably 20.0% by mass or less. is preferred.

Second, acrylic monomers preferably include functional group-containing monomers having functional groups in the molecule. By containing this functional group-containing monomer, the obtained acrylic polymer maintains independent particles in water due to the action of the functional group, and becomes excellent in water dispersibility.

Examples of functional group-containing monomers include monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomer), monomers having a carboxy group in the molecule (carboxy group-containing monomer), and monomers having an amino group in the molecule (amino group-containing monomer). are preferably mentioned. One of these functional group-containing monomers may be used alone, or two or more thereof may be used in combination.

Among the above functional group-containing monomers, hydroxyl group-containing monomers and carboxy group-containing monomers are preferable, and carboxy group-containing monomers are particularly preferable from the viewpoint of dispersibility in water.

Examples of carboxy group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among them, acrylic acid and methacrylic acid are preferable from the viewpoint of dispersibility in water. These may be used alone or in combination of two or more.

The functional group-containing monomer is preferably contained in an amount of 0.3% by mass or more, more preferably 0.5% by mass or more, and particularly 0.7% by mass or more, as a monomer unit constituting the acrylic polymer. It is preferably contained in an amount of 1.0% by mass or more. In addition, it is preferably contained in an amount of 20.0% by mass or less, more preferably 10.0% by mass or less, particularly preferably 5.0% by mass or less, and further preferably 4.0% by mass or less. is preferred.

The average particle diameter (D50) of the emulsion polymer (A) is preferably 50 nm or more, more preferably 80 nm or more, particularly preferably 100 nm or more, and further preferably 130 nm or more. preferable. As a result, it is possible to prevent the viscosity of the coating solution of the pressure-sensitive adhesive from becoming too high, and to obtain excellent coatability. In addition, since a large amount of emulsifier is not required, it is possible to prevent deterioration in durability of the adhesive. On the other hand, the average particle diameter (D50) is preferably 400 nm or less, more preferably 350 nm or less, particularly preferably 300 nm or less, further preferably 250 nm or less. Thereby, the pressure-sensitive adhesive layer exhibits better adhesion. Moreover, when the average particle size (D50) is within the above range, the obtained pressure-sensitive adhesive exhibits more excellent cohesive strength. In addition, the average particle diameter (D50) in this specification is a value measured by a dynamic light scattering method.

The content of the emulsion polymer (A) in the adhesive P is preferably 80% by mass or more, more preferably 85% by mass or more, particularly preferably 90% by mass or more, and further is preferably 95% by mass or more. In addition, the content is preferably 99.5% by mass or less, more preferably 99.0% by mass or less, particularly preferably 98.5% by mass or less, and further 98.0% by mass. % or less is preferable.

(2) Active energy ray-curable resin (B)
The active energy ray-curable resin (B) is not particularly limited as long as it is a component that is cured by irradiation with an active energy ray, and may be a monomer, an oligomer or a polymer, or a mixture thereof. . In this specification, for the sake of convenience, a monomer is also included in the concept of "resin".

The active energy ray-curable resin (B) is preferably an emulsion resin. The term "emulsion-based resin" as used herein includes, in addition to emulsion-polymerized oligomers or polymers, emulsions of monomers or oligomers or polymers polymerized by a method other than emulsion polymerization.

The active energy ray-curable resin (B) as a monomer is preferably a polyfunctional acrylate-based monomer. Examples of polyfunctional acrylate monomers include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate. , neopentyl glycol adipate di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphate di( Bifunctional types such as meth)acrylate, di(acryloxyethyl)isocyanurate, allylated cyclohexyl di(meth)acrylate; trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipenta Erythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl) isocyanurate, ε-caprolactone-modified tris-(2-(meth)acryloxy trifunctional type such as ethyl) isocyanurate; tetrafunctional type such as diglycerin tetra(meth)acrylate and pentaerythritol tetra(meth)acrylate; pentafunctional type such as propionic acid-modified dipentaerythritol penta(meth)acrylate; Hexafunctional types such as erythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and the like are included. Polyfunctional acrylate-based monomers preferably have a molecular weight of less than 1,000. These may be used individually by 1 type, and may be used in combination of 2 or more type.

Active energy ray-curable resin (B) as an oligomer is preferably an active energy ray-curable acrylate-based oligomer. Examples of such acrylate oligomers include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and silicone acrylate.

Polyester acrylate-based oligomers are produced, for example, by esterifying the hydroxyl groups of a polyester oligomer having hydroxyl groups at both ends with (meth)acrylic acid obtained by condensation of a polycarboxylic acid and a polyhydric alcohol, or by esterifying a polycarboxylic acid can be obtained by esterifying the terminal hydroxyl group of the oligomer obtained by adding an alkylene oxide to (meth)acrylic acid.

Epoxy acrylate-based oligomers can be obtained, for example, by reacting (meth)acrylic acid with the oxirane ring of a relatively low-molecular-weight bisphenol-type epoxy resin or novolak-type epoxy resin for esterification. A carboxyl-modified epoxy acrylate oligomer obtained by partially modifying this epoxy acrylate oligomer with a dibasic carboxylic acid anhydride can also be used.

A urethane acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by reacting a polyether polyol or polyester polyol with a polyisocyanate with (meth)acrylic acid. A polyol acrylate-based oligomer can be obtained by esterifying the hydroxyl groups of a polyether polyol with (meth)acrylic acid.

The weight average molecular weight of the acrylate oligomer is preferably 50,000 or less, particularly preferably 500 to 30,000, and further preferably 800 to 10,000. These acrylate-based oligomers may be used singly or in combination of two or more. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

The active energy ray-curable resin (B) as a polymer is preferably an adduct acrylate polymer in which a group having a (meth)acryloyl group is introduced into the side chain. Such an adduct acrylate polymer uses a copolymer of a (meth)acrylic acid ester and a monomer having a crosslinkable functional group in the molecule, and a part of the crosslinkable functional group of the copolymer is , (meth)acryloyl group and a compound having a group reactive with a crosslinkable functional group.

When the active energy ray-curable resin (B) is an emulsion resin, its average particle size (D50) is preferably 50 nm or more, more preferably 80 nm or more, and particularly preferably 100 nm or more. , and more preferably 130 nm or more. Also, the average particle diameter (D50) is preferably 400 nm or less, more preferably 350 nm or less, particularly preferably 300 nm or less, further preferably 250 nm or less. When the average particle diameter (D50) of the active energy ray-curable resin (B) is within the above range, the dispersion stability of the particles is good, and the compatibility with the emulsion polymer (A) is high. The transparency and durability of the pressure-sensitive adhesive layer are improved.

The content of the active energy ray-curable resin (B) in the adhesive P is preferably at least 0.5 parts by mass, and at least 1 part by mass with respect to 100 parts by mass of the emulsion polymer (A). More preferably, the amount is 2 parts by mass or more, and more preferably 3 parts by mass or more. Thereby, the cohesive force of the adhesive P can be effectively improved. In addition, the content of the active energy ray-curable resin (B) is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less, and further is preferably 8 parts by mass or less. As a result, the adhesion exhibited by the emulsion polymer (A) can be maintained satisfactorily.

(3) Photoinitiator (C)
When ultraviolet rays are used as the active energy ray for curing the active energy ray-curable resin (B), the adhesive P preferably further contains a photopolymerization initiator (C). By containing the photopolymerization initiator (C) in this way, the active energy ray-curable resin (B) can be efficiently polymerized, and the polymerization curing time and the irradiation dose of the active energy ray can be reduced. can.

Examples of such a photopolymerization initiator (C) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy -2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1-[4- (methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylamino Benzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiary-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2 , 4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 2,4 ,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone, and lithium phenyl (2,4,6-trimethylbenzoyl) phosphinate. These may be used alone or in combination of two or more.

The content of the photopolymerization initiator (C) in the adhesive P is preferably 0.1 parts by mass or more, and 0.2 parts by mass with respect to 100 parts by mass of the active energy ray-curable resin (B). It is more preferably 0.3 parts by mass or more, and more preferably 0.5 parts by mass or more. The content of the photopolymerization initiator (C) is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, particularly preferably 3 parts by mass or less, and further preferably 1 part by mass or less. It is preferably no more than parts by mass.

(4) Various Additives The pressure-sensitive adhesive P may optionally contain various additives commonly used in emulsion-based pressure-sensitive adhesives or acrylic pressure-sensitive adhesives, such as silane coupling agents, ultraviolet absorbers, antistatic agents, and tackifiers. agents, antioxidants, light stabilizers, softeners, fillers, refractive index modifiers, rust inhibitors and the like can be added. It should be noted that a polymerization solvent and a dilution solvent, which will be described later, are not included in the additives constituting the adhesive composition P.

It is preferable that the adhesive P in this embodiment does not contain a thermal cross-linking agent such as an epoxy-based cross-linking agent, or that the content thereof is small. When a predetermined amount of the thermal cross-linking agent is contained, the cohesive force is improved, but the adhesion is lowered, and the effect of improving the adhesion by the active energy ray-curable resin (B) tends to be reduced. When the adhesive P contains a thermal cross-linking agent, the content is preferably 1.0% by mass or less, particularly preferably 0.5% by mass or less, and further preferably 0.1% by mass or less. is preferably

2. Production of Adhesive To produce the adhesive P, first, an emulsion polymer (A) is prepared by an emulsion polymerization method. When the emulsion polymer (A) is an acrylic polymer, one or two or more acrylic monomers, an emulsifier, and a polymerization initiator are added to water and mixed with stirring to obtain an emulsion. Emulsion polymerization is carried out by radical polymerization. As the emulsifier, a reactive emulsifier having a radically polymerizable functional group such as a propenyl group or an allyl ether group introduced into the molecule is preferably used.

The polymerization initiator is preferably a water-soluble polymerization initiator. As the water-soluble polymerization initiator, the same photopolymerization initiator (C) as described above can be used.

When the active energy ray-curable resin (B) is an emulsion resin, the active energy ray-curable resin (B) is prepared by emulsion polymerization in the same manner as described above, or active energy ray-curable prepared by another polymerization method. The organic resin (B) is added to water together with an emulsifier and mixed with stirring to obtain an emulsion.

After the emulsion-based polymer (A) and the active energy ray-curable resin (B) are obtained, if desired, the photopolymerization initiator (C), additives, and water are added to the emulsion containing them and thoroughly mixed. Thus, a water-based adhesive P (coating solution) can be obtained.

The concentration/viscosity of the coating solution prepared in this manner is not particularly limited as long as it is within the range that allows coating, and can be appropriately selected according to the situation. For example, it is diluted with water so that the concentration of the adhesive P is 10 to 60% by mass.

3. Physical Properties (1) Gel Fraction The gel fraction of the adhesive P is preferably 40% or more, more preferably 50% or more, particularly preferably 60% or more, further preferably 70% or more. is preferably Further, the gel fraction of the adhesive P is preferably 90% or less, more preferably 85% or less, particularly preferably 80% or less, further preferably 75% or less. . By setting the gel fraction of the pressure-sensitive adhesive P to the above range, the gel fraction after curing with active energy rays tends to be within a preferable range. In addition, the method for measuring the gel fraction in the present specification is as shown in the test examples described later.

The gel fraction of the adhesive P after curing with active energy rays is preferably 60% or more, more preferably 65% or more, particularly preferably 70% or more, further preferably 75% or more. Preferably. As a result, the adhesive P after curing with active energy rays exhibits a high cohesive force and is excellent in blister resistance. In the pressure-sensitive adhesive P, it is possible to achieve a high gel fraction as described above while maintaining good adhesion. In addition, the gel fraction of the adhesive P after active energy ray curing is preferably 99% or less, more preferably 95% or less, particularly preferably 90% or less, and further preferably 85%. or less, and most preferably 80% or less. As a result, the adhesion of the adhesive P to the adherend after curing with active energy rays becomes more excellent. In this specification, the term "after curing with active energy rays" refers to a state in which the adhesive is cured by irradiation with active energy rays to such an extent that it is no longer cured. Specifically, the gel fraction of the adhesive due to irradiation with active energy rays It refers to the state in which the increase in is less than 3 points.

(2) Strain amount (creep property)
The strain amount measured after 3757 seconds of continuously applying a stress of 3000 Pa to the adhesive P is preferably 120% or less, more preferably 100% or less, and particularly preferably 80% or less. , and more preferably 60% or less. Further, the strain amount of the adhesive P is preferably 10% or more, more preferably 20% or more, particularly preferably 30% or more, and further preferably 40% or more. . By setting the amount of strain of the adhesive P to the above range, the amount of strain after curing with active energy rays tends to fall within a preferable range. The details of the method for measuring the amount of strain in this specification are as shown in the test examples described later.

The strain amount measured after 3757 seconds of continuously applying a stress of 3000 Pa to the adhesive P after the active energy ray curing is preferably 40% or less, more preferably 35% or less, particularly 30%. It is preferably 25% or less, more preferably 25% or less. As a result, the adhesive P after curing with active energy rays exhibits a high cohesive force and is excellent in blister resistance. In the adhesive P, it is possible to achieve a low strain amount as described above while maintaining good adhesion. Further, the strain amount of the adhesive P after active energy ray curing is preferably 1% or more, more preferably 3% or more, particularly preferably 5% or more, and further preferably 10%. It is preferable that it is above. As a result, the adhesion of the adhesive P to the adherend after curing with active energy rays becomes more excellent.

(3) Storage modulus G'
The storage modulus G'(25) of the adhesive P at 25°C is preferably 0.050 MPa or more, more preferably 0.060 MPa or more, particularly preferably 0.070 MPa or more, and further is preferably 0.080 MPa or more. Thereby, the workability of the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive P is improved. In addition, the storage elastic modulus G′(25) is preferably 0.20 MPa or less, more preferably 0.18 MPa or less, particularly preferably 0.16 MPa or less, further preferably 0.14 MPa. The following are preferable. As a result, the adhesiveness to the adherend is excellent at the time of sticking. Moreover, since the storage elastic modulus G'(25) of the pressure-sensitive adhesive P is in the above range, the storage elastic modulus G'(25) after curing with active energy rays tends to be within a preferable range.

The storage elastic modulus G′(25) at 25° C. of the adhesive P after curing with active energy rays is preferably 0.08 MPa or more, more preferably 0.10 MPa or more, and particularly 0.12 MPa or more. It is preferably 0.15 MPa or more. Thereby, the blister resistance of the adhesive P after curing with active energy rays becomes more excellent. In addition, the storage elastic modulus G′(25) of the adhesive P after curing with active energy rays is preferably 0.40 MPa or less, more preferably 0.30 MPa or less, and particularly 0.25 MPa or less. It is preferably 0.20 MPa or less. As a result, the adhesion of the adhesive P to the adherend after curing with active energy rays becomes more excellent.

The storage modulus G'(-20) of the adhesive P at -20°C is preferably 1.5 MPa or less, more preferably 1.3 MPa or less, and particularly preferably 1.2 MPa or less. , and more preferably 1.0 MPa or less. As a result, the instantaneous adhesiveness of the pressure-sensitive adhesive P to the adherend becomes more excellent. The storage elastic modulus G'(-20) is preferably 0.2 MPa or more, more preferably 0.3 MPa or more, particularly preferably 0.4 MPa or more, and further preferably 0.4 MPa or more. It is preferably 45 MPa or more. Thereby, the cohesive force of the adhesive P becomes excellent.

The storage elastic modulus G'(-20) of the adhesive P after curing with active energy rays at -20°C is preferably 3.0 MPa or less, more preferably 2.5 MPa or less, and particularly 2.0 MPa. It is preferably 1.5 MPa or less, more preferably 1.5 MPa or less. As a result, the adhesive P after curing with active energy rays also has excellent adhesion to the adherend. In addition, the storage elastic modulus G′ (−20) after curing with active energy rays is preferably 0.5 MPa or more, more preferably 0.6 MPa or more, and particularly 0.7 MPa or more. It is preferably 0.8 MPa or more, more preferably 0.8 MPa or more. Thereby, the blister resistance of the adhesive P after curing with active energy rays becomes more excellent.

The storage modulus G'(85) of the adhesive P at 85°C is preferably 0.010 MPa or more, more preferably 0.015 MPa or more, particularly preferably 0.020 MPa or more, and further is preferably 0.025 MPa or more. In addition, the storage elastic modulus G′(85) is preferably 0.080 MPa or less, more preferably 0.070 MPa or less, particularly preferably 0.060 MPa or less, further preferably 0.055 MPa. The following are preferable. Since the storage elastic modulus G'(85) of the pressure-sensitive adhesive P is within the above range, the storage elastic modulus G'(85) after curing with active energy rays tends to fall within a preferable range.

The storage elastic modulus G′(85) at 85° C. of the adhesive P after curing with active energy rays is preferably 0.030 MPa or more, more preferably 0.035 MPa or more, and particularly 0.040 MPa or more. It is preferably 0.042 MPa or more. This makes the blister resistance more excellent. In addition, the storage elastic modulus G′(85) after active energy ray curing is preferably 0.080 MPa or less, more preferably 0.075 MPa or less, and particularly preferably 0.070 MPa or less. and more preferably 0.065 MPa or less. As a result, the adhesion of the adhesive P to the adherend becomes more excellent.

The storage modulus in this specification is a value measured by a torsional shear method at a measurement frequency of 1 Hz in accordance with JIS K7244-6. Specifically, it is as shown in the test examples described later. Moreover, the method for measuring the gel fraction of the pressure-sensitive adhesive is as shown in the test examples described later.

[Adhesive sheet]
A pressure-sensitive adhesive sheet according to an embodiment of the present invention comprises at least a pressure-sensitive adhesive layer, and preferably a release sheet is laminated on one side or both sides of the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive sheet according to the present embodiment is preferably used for bonding one member and another member. It is preferably used in the case of permeable materials. A hard body is preferably used as the member. Moreover, as the above-mentioned member, a member constituting a display body is preferably mentioned. Therefore, the pressure-sensitive adhesive sheet according to the present embodiment is preferably used for optical applications, but it is not limited to this.

FIG. 1 shows a specific configuration as an example of the pressure-sensitive adhesive sheet according to this embodiment.
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 according to one embodiment includes two

release sheets

12a and 12b, and the two

release sheets

12a and 12b so as to be in contact with the release surfaces of the two

release sheets

12a and 12b. , 12b and an active energy ray-curable adhesive layer 11 sandwiched between them. In this specification, the release surface of the release sheet refers to the surface of the release sheet that has releasability, and includes both the surface that has been subjected to a release treatment and the surface that exhibits releasability without being subjected to a release treatment. .

1. Each member 1-1. Adhesive Layer The adhesive layer 11 is made of the adhesive, preferably the adhesive P, according to the embodiment described above. This adhesive layer 11 is preferably formed by applying an application solution of the adhesive P to a desired object and then drying it. Drying is preferably performed by heat treatment.

The heating temperature of the heat treatment is preferably 50 to 150°C, particularly preferably 70 to 120°C. The heating time is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes.

The lower limit of the thickness of the pressure-sensitive adhesive layer 11 (value measured according to JIS K7130) is preferably 1 μm or more, more preferably 3 μm or more, particularly preferably 5 μm or more. It is preferably 10 μm or more. Thereby, the desired adhesive strength is exhibited and the blister resistance becomes more excellent. The upper limit of the thickness of the pressure-sensitive adhesive layer 11 is preferably 300 μm or less, more preferably 150 μm or less, particularly preferably 100 μm or less, further preferably 50 μm or less. Thereby, workability becomes favorable.

1-2. Release

Sheet Release sheets

12a and 12b protect the active energy ray-curable adhesive layer 11 until the adhesive sheet 1 is used, and are peeled off when the adhesive sheet 1 (adhesive layer 11) is used. . In the adhesive sheet 1 according to this embodiment, one or both of the

release sheets

12a and 12b are not necessarily required.

Examples of the

release sheets

12a and 12b include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, and polybutylene. Terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluorine A resin film or the like is used. Crosslinked films of these are also used. Furthermore, a laminated film of these may be used.

The release surfaces of the

release sheets

12a and 12b (especially the surfaces in contact with the adhesive layer 11) are preferably subjected to a release treatment. Examples of release agents used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. Of the

release sheets

12a and 12b, it is preferable that one of the release sheets is a heavy release type release sheet with a large release force, and the other release sheet is a light release type release sheet with a small release force.

Although there are no particular restrictions on the thickness of the

release sheets

12a and 12b, it is usually about 20 to 150 μm.

2. Manufacture of Adhesive Sheet As an example of manufacturing the adhesive sheet 1, the adhesive layer 11 was formed by applying the coating solution of the adhesive P to the release surface of one of the release sheets 12a (or 12b) and drying. After that, the release surface of the other release sheet 12b (or 12a) is overlaid on the pressure-sensitive adhesive layer 11 . As a result, the pressure-sensitive adhesive sheet 1 is obtained. The conditions for the heat treatment are as described above.

As another example of manufacturing the adhesive sheet 1, the coating solution of the adhesive P is applied to the release surface of one release sheet 12a, dried to form a coating layer, and the release sheet 12a with the coating layer is formed. obtain. A coating solution of the adhesive P is applied to the release surface of the other release sheet 12b and dried to form a coating layer, thereby obtaining a release sheet 12b with a coating layer. Then, the release sheet 12a with the coating layer and the release sheet 12b with the coating layer are pasted together so that both coating layers are in contact with each other. As a result, the laminated coating layer becomes the adhesive layer 11, and the adhesive sheet 1 is obtained. According to this production example, even when the pressure-sensitive adhesive layer 11 is thick, it is possible to produce stably.

As a method for applying the coating solution of the adhesive composition P, 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.

3. Physical Properties (1) Adhesive Strength The adhesive strength of the adhesive layer 11 (before active energy ray irradiation) of the adhesive sheet 1 according to the present embodiment to soda lime glass is preferably 3 N/25 mm or more as a lower limit, particularly 5 N. /25 mm or more, more preferably 8 N/25 mm or more. When the lower limit of the adhesive strength of the adhesive sheet 1 is above, good handleability is obtained, and the blister resistance after curing with active energy rays is more excellent. On the other hand, the upper limit of the adhesive strength is not particularly limited, but reworkability may be required in some cases. From such a viewpoint, the adhesive strength is preferably 30 N/25 mm or less, more preferably 25 N/25 mm or less, and particularly preferably 20 N/25 mm or less. The adhesive strength is basically the adhesive strength measured by the 180-degree peeling method according to JIS Z0237:2009, and the specific test method is as shown in the test examples described later.

Adhesion to soda lime glass when the adhesive layer 11 in the adhesive sheet 1 according to the present embodiment is attached to soda lime glass and then cured with active energy rays (post-curing adhesive layer 11 ′) The lower limit of the force (after irradiation with active energy rays) is preferably 3 N/25 mm or more, particularly preferably 8 N/25 mm or more, further preferably 13 N/25 mm or more. This makes the blister resistance more excellent. On the other hand, the upper limit of the adhesive strength is not particularly limited, but reworkability may be required in some cases. From such a viewpoint, the adhesive strength is preferably 30 N/25 mm or less, more preferably 25 N/25 mm or less, and particularly preferably 20 N/25 mm or less.

(2) Haze value The haze value of the adhesive layer 11 is preferably 5% or less, more preferably 3% or less, particularly preferably 2% or less, further preferably 1% or less. is preferred. As a result, the transparency is high and the film is suitable for optical applications (for display). The lower limit of the haze value of the pressure-sensitive adhesive layer 11 is most preferably 0%, but may be 0.1% or more. The preferred haze value of the adhesive layer 11 after curing with active energy rays (post-curing adhesive layer 11' described later) is also the same as above. The haze value in this specification is a value measured according to JIS K7136:2000.

(3) Total light transmittance The total light transmittance of the adhesive layer 11 is preferably 99% or more. When the total light transmittance of the pressure-sensitive adhesive layer 11 is above, the transparency is very high, and it is particularly suitable for optical applications (for displays). The upper limit of the total light transmittance of the adhesive layer 11 is most preferably 100%, but may be 99.5% or less. The preferred total light transmittance of the adhesive layer 11 after curing with active energy rays (post-curing adhesive layer 11' described later) is also the same as above. The total light transmittance in this specification is a value measured according to JIS K7361-1:1997.

[Construction]
A structure can be manufactured using the adhesive (adhesive P) or the adhesive sheet (adhesive sheet 1) according to the embodiment described above. An example of the structure includes one display body constituting member, another display body constituting member, and a post-curing adhesive layer for bonding the one display body constituting member and the other display body constituting member to each other. It is a construct. The structure according to the present embodiment may be one member constituting the display body, or may be the display body itself.

As for the configuration of the one display body component and the other display body component, for example, one of the one display body component and the other display body component has a plastic plate and the other has a glass plate. A preferred configuration is

The post-curing adhesive layer is a post-curing adhesive layer obtained by subjecting the adhesive layer of the adhesive or adhesive sheet according to the above-described embodiment to active energy ray curing.

FIG. 2 shows a specific configuration as an example of the configuration according to this embodiment.
As shown in FIG. 2, the structure 2 according to one embodiment of the present invention includes a first display body forming member 21 (one display body forming member) and a second display body forming member 22 (another display body forming member). and a post-curing adhesive layer 11' positioned therebetween for adhering the first display body-constituting member 21 and the second display body-constituting member 22 to each other.

The post-curing adhesive layer 11' of the structure 2 is obtained by curing the adhesive layer 11 of the adhesive sheet 1 described above by irradiation with active energy rays. In the post-curing adhesive that constitutes the post-curing adhesive layer 11′, the network structure formed by the emulsion polymer (A) is entangled with the polymerized active energy ray-curable resin (B) to form a higher-order structure. presumed to form Such a structure exhibits excellent blister resistance.

The thickness of the post-curing adhesive layer 11 ′ is basically the same as the thickness of the adhesive layer 11 of the adhesive sheet 1 .

The structure 2 may be, for example, a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, a member that constitutes a part of a display such as electronic paper, The display body itself may be used. Note that the display may be a touch panel.

Specifically, the first display body constituent member 21 is preferably a protective panel made of a plastic plate or a laminate including a plastic plate.

Here, when the plastic plate is usually placed under high temperature conditions, for example, 85° C., the internal low boiling point component evaporates, and at the interface between the plastic plate and the post-curing pressure-sensitive adhesive layer 11′, There is a possibility that blisters such as air bubbles, floating, and peeling may occur. However, even if the structure 2 according to the present embodiment includes such a plastic plate, the post-curing adhesive layer 11' is derived from the adhesive sheet 1 according to the embodiment described above. It is possible to satisfactorily suppress the occurrence of blisters.

The plastic plate is not particularly limited, and examples thereof include acrylic resin plates such as a polycarbonate resin (PC) plate and a polymethyl methacrylate resin (PMMA) plate, acrylic resin such as a polymethyl methacrylate resin layer on a polycarbonate resin plate. Examples include a plastic plate having laminated layers. The above-mentioned polycarbonate resin plate may contain a resin other than polycarbonate resin as a constituent material, and the above-mentioned acrylic resin plate may contain a resin other than acrylic resin as a constituent material. may contain.

The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm, particularly preferably 0.6 to 2.5 mm, and more preferably 1 to 5 mm. 2.1 mm.

Various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, anti-glare layer, etc.) may be provided on one or both sides of the plastic plate, or an optical member may be laminated. good too. Moreover, the transparent conductive film and the metal layer may be patterned.

Examples of the optical member include anti-scattering films, polarizing plates (polarizing films), polarizers, retardation plates (retardation films), viewing angle compensation films, brightness enhancement films, contrast enhancement films, liquid crystal polymer films, and diffusion films. , transflective films, transparent conductive films, and the like. Examples of the anti-scattering film include a hard coat film in which a hard coat layer is formed on one side of a base film.

Specifically, the second display member constituting member 22 is preferably an optical member made of a glass plate or a laminated body including a glass plate. Examples of such optical members include display modules such as liquid crystal (LCD) modules, light emitting diode (LED) modules, organic electroluminescence (organic EL) modules, optical members as part of display modules, or display modules. Laminates containing modules can be mentioned.

Examples of the glass plate include, but are not limited to, chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, and barium borosilicate. Glass etc. are mentioned. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 10 mm, preferably 0.2 to 5 mm, more preferably 0.8 to 2 mm.

Various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, antiglare layer, etc.) may be provided on one side or both sides of the glass plate constituting the second display member constituting member 22. Alternatively, optical members may be laminated. Moreover, the transparent conductive film and the metal layer may be patterned. Examples of the optical member include those described above.

When the first display body constituting member 21 is a protective panel, the printed layer 3 may be formed in a frame shape on the post-curing adhesive layer 11 ′ side of the first display body constituting member 21 .

In order to manufacture the structure 2, as an example, one release sheet 12a of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is transferred to the printed layer of the first display body constituent member 21. 3 is pasted on the side on which 3 is present.

Next, the other release sheet 12b is peeled off from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 of the adhesive sheet 1 and the second display member constituting member 22 are laminated to obtain a laminate. . As another example, the bonding order of the first display body forming member 21 and the second display body forming member 22 may be changed.

After that, the adhesive layer 11 in the laminate is irradiated with active energy rays. As a result, the active energy ray-curable resin (B) in the pressure-sensitive adhesive layer 11 is polymerized, and the pressure-sensitive adhesive layer 11 is cured to form a cured pressure-sensitive adhesive layer 11'. Irradiation of energy rays to the pressure-sensitive adhesive layer 11 is usually carried out through either the first display member constituting member 21 or the second display member constituting member 22, preferably through the first display member as a protective panel. It is carried out over the constituent member 21 .

Here, active energy rays refer to electromagnetic waves or charged particle rays that have energy quanta, and specifically include ultraviolet rays and electron beams. Among active energy rays, ultraviolet rays are particularly preferable because they are easy to handle.

Irradiation with ultraviolet rays can be performed by a high-pressure mercury lamp, an electrodeless lamp, an LED lamp, a xenon lamp, or the like, and the irradiation amount of ultraviolet rays is preferably about 50 to 1000 mW/cm ² . The amount of light is preferably 50 to 10000 mJ/cm ² , more preferably 80 to 5000 mJ/cm ² and particularly preferably 200 to 2000 mJ/cm ² . On the other hand, electron beam irradiation can be performed by an electron beam accelerator or the like, and the electron beam irradiation dose is preferably about 10 to 1000 krad.

In the composition 2, since the adhesive layer 11′ after curing has excellent blister resistance, the composition 2 is placed under high temperature and high humidity conditions (eg, 85° C., 85% RH, 12 hours), and the first Even if outgassing is generated from the second display body constituting member 21 and/or the second display body constituting member 22, air bubbles, floating, and peeling occur at the interface between the post-curing adhesive layer 11' and the display

body constituting members

21 and 22. The occurrence of such blisters is suppressed.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is meant to include all design changes and equivalents that fall within the technical scope of the present invention.

For example, one of the

release sheets

12a and 12b in the adhesive sheet 1 may be omitted.

Although the present invention will be described in more detail with reference to examples and the like, the scope of the present invention is not limited to these examples and the like.

[Preparation Example 1] Preparation of emulsion polymer (A) Into a four-necked flask equipped with a nitrogen gas inlet tube, a thermometer, a reflux condenser and a stirrer, 83 parts by mass of 2-ethylhexyl acrylate and 15 parts of methyl methacrylate were added. .5 parts by mass, 2.5 parts by mass of methacrylic acid, 1 part by mass of acrylic acid, 1 part by mass of polyoxyalkylene alkenyl ether ammonium sulfate (manufactured by Kao Corporation, product name "Latemul PD-104") as a reactive emulsifier, and distillation 80 parts by mass of water was added, and the mixture was sufficiently stirred and heated to 70°C. Thereafter, 0.3 parts by mass of potassium persulfate as a polymerization initiator was added, and emulsion polymerization was performed at 70° C. for 3 hours to prepare an acrylic polymer as emulsion polymer (A).

The particle size distribution of the acrylic polymer was measured by a dynamic light scattering method using a dynamic light scattering particle size distribution analyzer (manufactured by Microtrack Bell, product name "Nanotrac Wave"). The particle size (D50) was 150 nm.

[Preparation Example 2] Preparation of active energy ray-curable resin (B1) A four-necked flask equipped with a nitrogen gas inlet tube, a thermometer, a reflux condenser and a stirrer was charged with a urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., product Name "UA-122P", Mw: 1100, difunctional) 80 parts by mass, polyoxyalkylene alkenyl ether ammonium sulfate (manufactured by Kao Corporation, product name "Latemul PD-104") 15 parts by mass as a reactive emulsifier are added, and then While gradually adding 100 parts by mass of distilled water, the mixture was vigorously stirred at 80° C. for 1 hour to obtain an emulsion of urethane acrylate oligomer as the active energy ray-curable resin (B1).

The particle size distribution of the urethane acrylate oligomer was measured by a dynamic light scattering method using a dynamic light scattering particle size distribution analyzer (manufactured by Microtrac Bell, product name "Nanotrac Wave"). The diameter (D50) was 200 nm.

[Preparation Example 3] Preparation of active energy ray-curable resin (B2) A four-necked flask equipped with a nitrogen gas inlet tube, a thermometer, a reflux condenser and a stirrer was charged with a urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., product Name "UA-1100H", Mw: 800, hexafunctional) 80 parts by weight, polyoxyalkylene alkenyl ether ammonium sulfate (manufactured by Kao Corporation, product name "Latemul PD-104") 15 parts by weight as a reactive emulsifier are added, and then While gradually adding 100 parts by mass of distilled water, the mixture was vigorously stirred at 70° C. for 1 hour to obtain an emulsion of urethane acrylate oligomer as the active energy ray-curable resin (B2).

[Example 1]
100 parts by mass of the acrylic polymer as the emulsion polymer (A) obtained in Preparation Example 1 (solid content conversion value; the same applies hereinafter), and the active energy ray-curable resin (B1) obtained in Preparation Example 2 4.8 parts by mass of a urethane acrylate oligomer as a photopolymerization initiator (C1) and 0.6 parts by mass of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone in water. and thoroughly stirred to obtain an adhesive coating solution.

Here, Table 1 shows each composition (solid content conversion value) of the pressure-sensitive adhesive when the emulsion polymer (A) is 100 parts by mass (solid content conversion value). Details of abbreviations and the like in Table 1 are as follows.
[Emulsion polymer (A)]
2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate MAA: methacrylic acid AAc: acrylic acid
[Photoinitiator (C)]
C1: 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone C2: 1:1 (mass ratio) mixture of α-hydroxyalkylphenone and benzophenone (manufactured by IGM Resins, product name “OMNIRAD 500")
[Crosslinking agent]
Ethylene glycol diglycidyl ether (epoxy cross-linking agent; manufactured by Nagase ChemteX Corporation, product name “Denacol EX-810”)

The pressure-sensitive adhesive coating solution obtained above is applied to the release-treated surface of a heavy-release release sheet (manufactured by Lintec, product name: "SP-PET382150") in which one side of a polyethylene terephthalate film is release-treated with a silicone-based release agent. applied with a coater. Then, the coating layer was heat-treated at 90° C. for 1 minute to form a coating layer. Next, the coating layer on the heavy release release sheet obtained above and a light release release sheet obtained by releasing a polyethylene terephthalate film on one side with a silicone release agent (manufactured by Lintec, product name "SP-PET381031"). A pressure-sensitive adhesive sheet having an adhesive layer with a thickness of 25 μm, that is, a heavy-release release sheet/adhesive layer (thickness Thickness: 25 μm)/light release type release sheet.

The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness measuring instrument (manufactured by Teclock, product name "PG-02") in accordance with JIS K7130.

[Examples 2 to 5, Comparative Examples 1 to 3]
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that the type and amount of the active energy ray-curable resin (B) and the type and amount of the photopolymerization initiator (C) were changed as shown in Table 1. did.

In Comparative Examples 2 and 3, ethylene glycol diglycidyl ether (epoxy-based cross-linking agent; manufactured by Nagase ChemteX Corporation, product name "Denacol EX-810") was blended in the amounts shown in Table 1 as a cross-linking agent. Moreover, in these comparative examples, a curing period of 7 days was provided.

[Test Example 1] (Measurement of gel fraction)
The pressure-sensitive adhesive sheets produced in Examples and Comparative Examples were cut into a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200), and the mass was weighed with a precision balance. The mass of the adhesive alone was calculated by subtracting the mass of . Let the mass at this time be M1.

Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 72 hours. After that, the pressure-sensitive adhesive was taken out and air-dried for 24 hours in an environment of 23° C. and 50% relative humidity, and further dried in an oven at 80° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. Let the mass at this time be M2. A gel fraction (%) is represented by (M2/M1)×100. From this, the gel fraction (before UV; %) of the adhesive was derived. Table 2 shows the results.

In addition, the adhesive sheets produced in Examples 1 to 5 were irradiated with active energy rays under the following conditions through the light release type release sheet to cure the adhesive layer to form a cured adhesive layer. The gel fraction (after UV; %) was derived in the same manner as described above for the adhesive in the post-curing adhesive layer. Table 2 shows the results.

<Active energy ray irradiation conditions>
・Using a high-pressure mercury lamp ・Illuminance 200mW/cm ² , Light intensity 400mJ/cm ²
・Using “UVPF-A1” manufactured by Eye Graphics Co., Ltd. for UV illuminance and photometer

[Test Example 2] (Measurement of storage modulus)
A plurality of pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples were laminated to form a laminate having a thickness of 0.8 mm. A cylinder having a diameter of 8 mm (height of 0.8 mm) was punched out from the obtained laminate of pressure-sensitive adhesive layers, and this was used as a sample. For the above sample, in accordance with JIS K7244-6, using a viscoelasticity measuring device (manufactured by Anton paar, product name "MCR302"), by a torsional shear method under the following conditions -20 ° C., 25 ° C. and 85 ° C. The storage modulus G' (before UV; MPa) was measured. Table 2 shows the results.
Measurement frequency: 1Hz
Measurement temperature: -20°C, 25°C, 85°C

Further, for Examples 1 to 5, the same sample as above was irradiated with active energy rays (ultraviolet rays; UV) under the same conditions as in Test Example 1 to cure the adhesive. A later sample was obtained. For the obtained sample after irradiation with active energy rays, the storage modulus G' (after UV; MPa) at -20°C, 25°C and 85°C was measured in the same manner as the sample before irradiation with active energy rays. Table 2 shows the results.

[Test Example 3] (Measurement of haze value)
The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples were attached to glass to prepare measurement samples. After performing background measurement on glass, the haze value ( Before UV;%) was measured. Table 2 shows the results.

In addition, the adhesive sheets produced in Examples 1 to 5 were irradiated with active energy rays under the same conditions as in Test Example 1, and the adhesive layer was cured to form a cured adhesive layer. The haze value (after UV; %) of this cured pressure-sensitive adhesive layer was measured in the same manner as described above. Table 2 shows the results.

[Test Example 4] (Measurement of total light transmittance)
The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples were attached to glass to prepare measurement samples. After performing background measurement on glass, all the above measurement samples were measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name “SH-7000”) in accordance with JIS K7361-1: 1997. Light transmittance (before UV; %) was measured. Table 2 shows the results.

In addition, the adhesive sheets produced in Examples 1 to 5 were irradiated with active energy rays under the same conditions as in Test Example 1, and the adhesive layer was cured to form a cured adhesive layer. The total light transmittance (after UV; %) of the cured pressure-sensitive adhesive layer was measured in the same manner as described above. Table 2 shows the results.

[Test Example 5] (Measurement of adhesive strength)
The light-release type release sheet was peeled off from the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was coated with a polyethylene terephthalate (PET) film having an easy-adhesion layer (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360"). , thickness: 100 μm) to obtain a laminate of heavy release type release sheet/adhesive layer/PET film. The laminate thus obtained was cut to a width of 25 mm and a length of 100 mm.

In an environment of 23 ° C. and 50% RH, the heavy release type release sheet was peeled off from the laminate, and the exposed adhesive layer was applied to a soda lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd., product name “soda lime glass”, thickness thickness: 1.1 mm), and pressurized at 0.5 MPa and 50° C. for 20 minutes in an autoclave manufactured by Kurihara Seisakusho. Then, after leaving it for 24 hours under conditions of 23 ° C. and 50% RH, using a tensile tester (manufactured by Orientec, Tensilon), under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees, the PET film and The adhesive strength (before UV; N/25 mm) was measured when the laminate with the adhesive layer was peeled off from the adherend. Conditions other than those described here were measured in accordance with JIS Z0237:2009. Table 2 shows the results.

In addition, for the pressure-sensitive adhesive sheets produced in Examples 1 to 5, the pressure-sensitive adhesive layer was applied to the adherend in the same manner as described above, autoclaved, and left under conditions of 23 ° C. and 50% RH for 24 hours. After that, an active energy ray was irradiated through the PET film under the same conditions as in Test Example 1 to cure the pressure-sensitive adhesive layer. After curing, the adhesive layer was measured for adhesive strength (after UV; N/25 mm) in the same manner as described above. Table 2 shows the results.

[Test Example 6] (Measurement of strain amount)
A plurality of pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples were laminated to form a laminate having a thickness of 0.5 mm. A cylinder having a diameter of 8 mm (height of 0.5 mm) was punched out from the laminate of the pressure-sensitive adhesive layers thus obtained, and this was used as a sample.

For the above sample, using a viscoelasticity measuring device (manufactured by Anton paar, product name "MCR302"), the strain amount (%) measured 3757 seconds after applying a stress of 3000 Pa under the following conditions was measured. . Table 2 shows the results.
Measurement temperature: 25°C
Measurement points: 1000 points when stress is applied (logarithmic plot)

Further, for Examples 1 to 5, the same sample as above was irradiated with active energy rays (ultraviolet rays; UV) under the same conditions as in Test Example 1 to cure the adhesive. A later sample was obtained. The strain amount (%) of the obtained sample after irradiation with active energy rays was measured in the same manner as the sample before irradiation with active energy rays. Table 2 shows the results.

[Test Example 7] (Evaluation of blister resistance)
The light release type release sheet was peeled off from the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was covered with a transparent conductive film (manufactured by Oike Kogyo Co., Ltd., product name “Tetraite TCF”, thickness: 188 μm). Affixed to the conductive surface side to obtain a transparent conductive film with an adhesive layer. The heavy release type release sheet was peeled off from the transparent conductive film with the adhesive layer obtained above, and the exposed adhesive layer was transferred to a plastic plate (Mitsubishi Gas Kagaku Co., Ltd., product name "Iupilon Sheet MR58U", thickness: 0.8 mm) was attached to the PC board side. Then, it was autoclaved for 20 minutes under the conditions of 50° C. and 0.5 MPa, and left at normal pressure, 23° C. and 50% RH for 24 hours.

After that, it was stored for 12 hours under high temperature and high humidity conditions of 85° C. and 85% RH. Then, the state of the interface between the pressure-sensitive adhesive layer and the adherend (transparent conductive film, plastic plate) was visually observed, and the blister resistance was evaluated according to the following criteria.
◯: There was no air bubble, floating, or peeling.
Δ: Air bubbles, floating, and peeling occurred partially.
x: Lifting and peeling occurred over a wide range.

In addition, for the pressure-sensitive adhesive sheets produced in Examples 1 to 5, the pressure-sensitive adhesive layer was applied to the adherend in the same manner as described above, autoclaved, and left under conditions of 23 ° C. and 50% RH for 24 hours. After that, an active energy ray was irradiated through the transparent conductive film under the same conditions as in Test Example 1 to cure the pressure-sensitive adhesive layer. After curing, the pressure-sensitive adhesive layer was evaluated for blister resistance in the same manner as described above. Table 2 shows the results.

As can be seen from Table 2, the post-curing pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive sheet obtained in the example has a small amount of strain, and therefore has high cohesive strength, high adhesive strength, and blister resistance. was excellent.

The pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, for laminating a protective panel containing a plastic plate and a display body component containing a glass plate in the production of various display panels.

DESCRIPTION OF SYMBOLS 1... Adhesive sheet 11...

Adhesive layer

12a, 12b... Release sheet 2... Structure 11'... Adhesive layer after hardening 21... First display body constituent member 22... Second display body constituent member 3... Printed layer

Claims

an emulsion polymer;
An adhesive containing an active energy ray-curable resin.
The adhesive according to claim 1, wherein the emulsion polymer is an acrylic polymer.
The adhesive according to claim 1, wherein the active energy ray-curable resin is an emulsion resin.
The adhesive according to claim 1, characterized by containing a photopolymerization initiator.
The adhesive according to claim 1, wherein the gel fraction of the adhesive after active energy ray curing is 60% or more and 99% or less.
The pressure-sensitive adhesive according to claim 1, wherein the strain amount measured after 3757 seconds of continuously applying a stress of 3000 Pa to the pressure-sensitive adhesive after curing with active energy rays is 1% or more and 40% or less. .
The adhesive according to claim 1, wherein the storage elastic modulus G'(25) at 25°C of the adhesive after active energy ray curing is 0.08 MPa or more and 0.40 MPa or less.
The adhesive according to claim 1, wherein the storage elastic modulus G'(-20) at -20°C of the adhesive after active energy ray curing is 0.15 MPa or more and 3.0 MPa or less.
The adhesive according to claim 1, wherein the storage elastic modulus G'(85) at 85°C of the adhesive after active energy ray curing is 0.03 MPa or more and 0.08 MPa or less.
A pressure-sensitive adhesive sheet comprising at least a pressure-sensitive adhesive layer,
A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive according to any one of claims 1 to 9.
two release sheets;
11. The pressure-sensitive adhesive sheet according to claim 10, further comprising the pressure-sensitive adhesive layer sandwiched between the two release sheets so as to be in contact with the release surfaces of the two release sheets.