CN116891699A - Adhesive sheet and display body - Google Patents

Abstract

The invention provides an adhesive sheet and a display body, which have excellent antistatic property even though the thickness of an adhesive layer is small, and can also exhibit good step following property. The adhesive sheet (1) is provided with an adhesive layer (11), wherein the thickness of the adhesive layer (11) is 1 [ mu ] m or more and less than 30 [ mu ] m, the adhesive constituting the adhesive layer (11) contains an antistatic agent, the gel fraction of the adhesive is 40% or more and 95% or less, the protective film is peeled from the substrate in a laminate composed of an ITO-PET film, the adhesive layer, a substrate and the protective film at a peeling rate of 2.0 m/min, and the peeling static voltage obtained by measuring the electrostatic potential at a position 2.0cm away from the exposed surface of the ITO-PET film after peeling for 2 seconds is 0.15kV or less.

Description

Adhesive sheet and display body

Technical Field

The present invention relates to an adhesive sheet for bonding two display body components together, and a display body obtained by using an adhesive layer of the adhesive sheet.

Background Art

Various mobile electronic devices such as mobile phones, smartphones, and tablet terminals in recent years have a display (display) using a display module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescent (organic EL) element, and the like.

In the display, a protection panel is usually provided on the surface side of the display module, and a gap is provided between the protection panel and the display module so that even if the protection panel is deformed by external force, the deformed protection panel will not hit the display module.

However, if there is a gap, that is, an air layer, the reflection loss of light due to the difference in refractive index between the protection panel and the air layer and between the air layer and the display module increases, which may deteriorate the image quality of the display.

Therefore, a scheme has been proposed to improve the image quality of the display by embedding the gap between the protective panel and the display module with an adhesive layer. However, sometimes the frame-shaped printed layer exists as a step difference on the display module side of the protective panel. If the adhesive layer does not follow the step difference, the adhesive layer will float near the step difference, thereby causing reflection loss of light. Therefore, the adhesive layer is required to have step difference tracking properties.

However, static electricity may be generated in the manufacturing process of the protection panel. If the protection panel is attached to the display module, especially to the liquid crystal cell, in a state where static electricity is generated, the alignment of liquid crystal molecules may be disturbed.

Therefore, in order to obtain effective antistatic performance, it has been proposed to add an antistatic agent to an adhesive composition (for example, Patent Documents 1 and 2).

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2007-316377

Patent Document 2: Japanese Patent Application Publication No. 2009-155585

Summary of the invention

Technical Problems to be Solved by the Invention

However, when the antistatic agent as described above is added to the adhesive composition, the durability of the obtained adhesive tends to be lower than usual. Therefore, as described above, when the adhesive layer containing the antistatic agent is attached to the protective panel in which the printed layer exists in the form of a step, under high temperature and high humidity conditions, floating or peeling sometimes occurs near the step of the adhesive layer, and sufficient step tracking performance cannot be obtained.

However, in recent years, the display panel has been significantly thinned, and with this, the adhesive layer is also required to be thinner. If the adhesive layer is thinner, it is difficult to fully obtain the above-mentioned step tracking property and antistatic property.

The present invention has been made in view of such actual circumstances, and an object of the present invention is to provide an adhesive sheet and a display body which are excellent in antistatic properties and can exhibit good step followability even when the thickness of the adhesive layer is thin.

Technical means to solve technical problems

In order to achieve the above-mentioned object, first, the present invention provides an adhesive sheet having an adhesive layer for bonding two display body components to each other, wherein the adhesive sheet is characterized in that the thickness of the adhesive layer is greater than 1 μm and less than 30 μm, the adhesive constituting the adhesive layer contains an antistatic agent, the gel fraction of the adhesive is greater than 40% and less than 95%, the protective film is peeled off from the substrate in a laminate consisting of an ITO-PET film, the adhesive layer, a substrate and a protective film at a peeling speed of 2.0 m/min, and after 2 seconds of peeling, the electrostatic potential at a position 2.0 cm away from the exposed surface of the ITO-PET film is measured to obtain a peeling speed of 2.0 m/min. The static voltage is below 0.15 kV, wherein the ITO-PET film is provided with a tin-doped indium oxide layer on one side of a polyethylene terephthalate film having a thickness of 125 μm, the adhesive layer is stacked on the tin-doped indium oxide layer of the ITO-PET film, the substrate is stacked on the adhesive layer and is provided with an acrylic hard coating layer having a thickness of 1.5 μm on one side of a polyethylene terephthalate film having a thickness of 125 μm, the protective film is stacked on the hard coating layer of the substrate and is provided with an acrylic adhesive layer having a thickness of 15 μm containing 0.98 mass % of potassium hexafluorophosphate on one side of a polyethylene terephthalate film having a thickness of 38 μm (Invention 1).

The adhesive sheet of the above invention (Invention 1) satisfies the above requirements, so even if the thickness of the adhesive layer is thin, it has excellent antistatic properties and also exhibits good step tracking properties. Specifically, even if a laminated body formed by laminating a glass plate with a step and a polyethylene terephthalate film through the above adhesive layer is placed under high temperature and high humidity conditions (e.g., 85°C, 85% RH, 500 hours), floating, peeling, etc. can be suppressed.

In the above invention (Invention 1), it is preferred that the step following rate of the pressure-sensitive adhesive layer is 10% or more (Invention 2).

In the above inventions (Inventions 1 and 2), it is preferred that the adhesive strength of the adhesive sheet to soda-lime glass is 1 N/25 mm or more (Invention 3).

In the above inventions (Inventions 1 to 3), it is preferred that the adhesive is a non-active energy ray-curable adhesive (Invention 4).

In the above inventions (Inventions 1 to 4), it is preferred that the adhesive contains a cross-linked product of a (meth)acrylate polymer, and the (meth)acrylate polymer contains a structural unit derived from a hard monomer having a glass transition temperature (Tg) of 70° C. or higher as a homopolymer, and a structural unit derived from a nitrogen atom-containing monomer (Invention 5).

In the above inventions (Inventions 1 to 5), it is preferred that the adhesive contains a crosslinked product of a (meth)acrylate polymer, and the (meth)acrylate polymer contains 1% by mass to 30% by mass of a structural unit derived from a reactive functional group-containing monomer (Invention 6).

In the above inventions (Inventions 1 to 6), it is preferred that the adhesive is formed by cross-linking an adhesive composition containing a (meth)acrylate polymer and a cross-linking agent, and the content of the cross-linking agent in the adhesive composition is greater than 0.1 parts by mass and less than 10 parts by mass relative to 100 parts by mass of the (meth)acrylate polymer (Invention 7).

In the above inventions (Inventions 1 to 7), it is preferred that the content of the antistatic agent in the adhesive is 0.1% by mass or more and 10% by mass or less (Invention 8).

In the above inventions (Inventions 1 to 8), it is preferred that the antistatic agent is an ionic compound (Invention 9).

In the above invention (Invention 9), it is preferred that the ionic compound is a nitrogen-containing onium salt or an alkali metal salt (Invention 10).

In the above invention (Invention 10), it is preferred that anions constituting the nitrogen-containing onium salt or the alkali metal salt are sulfonylimide anions or halogenated phosphoric acid anions (Invention 11).

In the above inventions (Inventions 1 to 11), it is preferred that the adhesive sheet includes two release sheets, and the adhesive layer is sandwiched by the release sheets so as to be in contact with release surfaces of the two release sheets (Invention 12).

Second, the present invention provides a display body, which comprises a display body constituent member, another display body constituent member, and an adhesive layer for bonding the one display body constituent member and the other display body constituent member to each other, wherein the display body is characterized in that the adhesive layer is formed by the adhesive layer of the adhesive sheet (Inventions 1 to 12) (Invention 13).

In the above invention (Invention 13), it is preferred that at least one of the one display constituting member and the other display constituting member has a step at least on a surface on a side to be bonded by the adhesive layer (Invention 14).

In the above inventions (Inventions 13 and 14), it is preferable that the one display body constituting member and the other display body constituting member are both hard plates (Invention 15).

Effects of the Invention

The adhesive sheet and the display of the present invention are excellent in antistatic properties even when the thickness of the adhesive layer is thin, and can also exhibit good step followability.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 2 is a cross-sectional view of a display according to an embodiment of the present invention.

Description of Reference Numerals

1: adhesive sheet; 11: adhesive layer; 12a, 12b: release sheets; 2: display body; 21: first display body constituent member; 22: second display body constituent member; 3: printed layer.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described.

[Adhesive sheet]

The adhesive sheet of this embodiment has an adhesive layer for bonding two display body constituent members to each other. The specific structure of the adhesive sheet and the display body constituent member will be described later.

The thickness of the adhesive layer of the present embodiment (value measured according to JIS K7130) is preferably 1 μm or more and less than 30 μm. In addition, it is preferred that the adhesive constituting the adhesive layer of the present embodiment contains an antistatic agent and has a gel fraction of 40% or more and 95% or less. In addition, the method for measuring the gel fraction is shown in the test examples described later.

Furthermore, it is preferred that the adhesive sheet (adhesive layer) of the present embodiment has a peeling static voltage measured as follows and be 0.15 kV or less. That is, a laminate consisting of an ITO-PET film, an adhesive layer of the present embodiment, a substrate and a protective film is prepared, wherein the ITO-PET film is formed with a tin-doped indium oxide (ITO) layer on one side of a polyethylene terephthalate (PET) film having a thickness of 125 μm, the adhesive layer is laminated on the tin-doped indium oxide layer of the ITO-PET film, the substrate is laminated on the adhesive layer and an acrylic hard coating layer having a thickness of 1.5 μm is formed on one side of the polyethylene terephthalate (PET) film having a thickness of 125 μm (the PET film side is in contact with the above-mentioned adhesive layer), the protective film is laminated on the hard coating layer of the substrate and an acrylic adhesive layer having a thickness of 15 μm containing 0.98 mass % of potassium hexafluorophosphate is formed on one side of a polyethylene terephthalate film having a thickness of 38 μm (the adhesive layer side is in contact with the hard coating layer). Then, the protective film was peeled off from the substrate in the laminate at a peeling speed of 2.0 m/min, and 2 seconds after the peeling, the electrostatic potential at a position 2.0 cm away from the exposed surface of the ITO-PET film was measured and used as the peeling static voltage. In addition, the details of the method for measuring the peeling static voltage are shown in the test examples described later.

Since the adhesive sheet of the present embodiment satisfies the above requirements, even if the thickness of the adhesive layer is relatively thin, the antistatic property is excellent, and good step tracking performance is also exhibited. Specifically, even if the laminated body formed by laminating the glass plate with a step difference and the polyethylene terephthalate film through the above adhesive layer is placed under high temperature and high humidity conditions (for example, 85°C, 85% RH, 500 hours), floating, peeling, etc. can be suppressed, and the step tracking rate described later can also be exhibited.

From the perspective of step tracking in the initial stage and under high temperature and high humidity conditions, the gel fraction of the adhesive of this embodiment is preferably 30% or more, more preferably 35% or more, particularly preferably 38% or more, and further preferably 40% or more. In addition, from the perspective of step tracking in the initial stage and under high temperature and high humidity conditions, and suppressing the increase in resistance value after the durability test, the gel fraction of the adhesive of this embodiment is preferably 95% or less, more preferably 85% or less, particularly preferably 80% or less, and further preferably 65% or less, wherein preferably 60% or less, and most preferably 55% or less. In addition, when the adhesive is an active energy ray-curable adhesive of the type that is cured by active energy ray irradiation after being attached to the adherend, the value of the gel fraction after active energy ray curing satisfies the above value. The method for determining the gel fraction is shown in the test example described later.

From the perspective of thin film, the thickness of the adhesive layer of this embodiment is preferably less than 30 μm, more preferably less than 28 μm, and particularly preferably less than 26 μm. In addition, from the perspective of antistatic properties and step tracking, the thickness of the adhesive layer is preferably more than 1 μm, more preferably more than 3 μm, and particularly preferably more than 5 μm.

From the perspective of antistatic properties, the peeling static voltage is preferably 0.15 kV or less, more preferably 0.13 kV or less, particularly preferably 0.11 kV or less, and further preferably 0.1 kV or less, and preferably less than 0.1 kV. The lower limit of the peeling static voltage is not particularly limited and may be 0 kV.

In the above-mentioned laminate, in the same manner as above, when the protective film is peeled off from a laminate in which a soda-lime glass plate having a thickness of 1.1 mm is laminated instead of the ITO-PET film, the peeling static voltage is preferably less than 0.7 kV, more preferably 0.6 kV or less, particularly preferably 0.5 kV or less, further preferably 0.46 kV or less, and particularly preferably 0.42 kV or less. The lower limit of the above-mentioned peeling static voltage is not particularly limited and may be 0 kV, but is generally preferably 0.1 kV or more, particularly preferably 0.2 kV or more, and further preferably 0.3 kV or more.

In the above-mentioned laminate, in the same manner as above, when the protective film is peeled off from a laminate in which a soda-lime glass plate having a thickness of 0.7 mm is laminated instead of the ITO-PET film, the peeling static voltage is preferably 0.9 kV or less, more preferably 0.7 kV or less, particularly preferably 0.6 kV or less, further preferably 0.55 kV or less, and particularly preferably 0.5 kV or less. The lower limit of the above-mentioned peeling static voltage is not particularly limited and may be 0 kV, but is generally preferably 0.1 kV or more, particularly preferably 0.2 kV or more, and further preferably 0.3 kV or more.

Antistatic agent can be used as long as it can exert the above-mentioned excellent antistatic property and good step tracking property, for example, ionic compounds, nonionic compounds, etc. can be listed, wherein, preferred ionic compounds. Ionic compounds can be liquid (ionic liquid) at room temperature, or solid (ionic solid). Here, the ionic compound in this specification refers to a compound formed by combining cations and anions mainly through electrostatic attraction. In addition, antistatic agent can be used alone or in combination of two or more.

As the ionic compound, nitrogen-containing onium salts, sulfur-containing onium salts, phosphorus-containing onium salts, alkali metal salts or alkaline earth metal salts are preferred. From the perspective of the above-mentioned peeling static voltage and the perspective of step tracking, nitrogen-containing onium salts or alkali metal salts are particularly preferred. The nitrogen-containing onium salt is preferably an ionic compound composed of a nitrogen-containing heterocyclic cation and its counter anion.

As the nitrogen-containing heterocyclic skeleton of the nitrogen-containing heterocyclic cation, a pyridine ring, a pyrimidine ring, an imidazole ring, a triazole ring, an indole ring, etc. are preferred, among which a pyridine ring or an imidazole ring is preferred. In addition, as the cation constituting the alkali metal salt, a lithium ion, a potassium ion or a sodium ion is preferred, and a lithium ion or a potassium ion is particularly preferred.

On the other hand, as the anion constituting the above-mentioned ionic compound, preferably a halogenated phosphoric acid anion or a sulfonyl imide anion can be listed. As the halogenated phosphoric acid anion, preferably hexafluorophosphate etc. can be listed. In addition, as the sulfonyl imide anion, preferably bis(fluoroalkylsulfonyl)imide or bis(fluorosulfonyl)imide etc. can be listed. Bis(fluoroalkylsulfonyl)imide can be bis(perfluoroalkylsulfonyl)imide, among which, preferably bis(trifluoromethanesulfonyl)imide etc. can be listed.

Specific examples of the nitrogen-containing onium salt having a pyridine ring and a halophosphate anion include 1-butyl-4-methylpyridinium hexafluorophosphate, 1-hexyl-3-methylpyridinium hexafluorophosphate, 1-hexyl-4-methylpyridinium hexafluorophosphate, 1-octylpyridinium hexafluorophosphate, 1-octyl-4-methylpyridinium hexafluorophosphate, 1-dodecylpyridinium hexafluorophosphate, 1-tetradecylpyridinium hexafluorophosphate, 1-hexadecylpyridinium hexafluorophosphate, 1-dodecyl-4-methylpyridinium hexafluorophosphate, 1-tetradecyl-4-methylpyridinium hexafluorophosphate, and 1-hexadecyl-4-methylpyridinium hexafluorophosphate. From the perspective of the above-mentioned peeling electrostatic voltage and the step followability, as the nitrogen-containing onium salt having a pyridine ring and a halophosphate anion, dialkylpyridinium hexafluorophosphate is preferred, and 1-hexyl-3-methylpyridinium hexafluorophosphate or 1-octyl-4-methylpyridinium hexafluorophosphate is particularly preferred.

Specific examples of the nitrogen-containing onium salt having a pyridine ring and a sulfonyl imide anion include 1-decylpyridinium bis(fluorosulfonyl)imide, 1-ethylpyridinium bis(fluorosulfonyl)imide, 1-butylpyridinium bis(fluorosulfonyl)imide, 1-hexylpyridinium bis(fluorosulfonyl)imide, 1-butyl-3-methylpyridinium bis(fluorosulfonyl)imide, 1-butyl-4-methylpyridinium bis(fluorosulfonyl)imide, 1-hexyl-3-methylpyridinium bis(fluorosulfonyl)imide, 1-butyl-3,4-dimethylpyridinium bis(fluorosulfonyl)imide, and 4-methyl-1-octylpyridinium bis(fluorosulfonyl)imide. From the perspective of the above-mentioned peeling static voltage and the step tracking property, as the nitrogen-containing onium salt having a pyridine ring and a sulfonyl imide anion, dialkylpyridinium bis(fluorosulfonyl)imide is preferred, and 4-methyl-1-octylpyridinium bis(fluorosulfonyl)imide is particularly preferred. In particular, the above-mentioned antistatic agent is preferred because it is easy to meet the above-mentioned peeling static voltage and improve the step tracking property.

Specific examples of the nitrogen-containing onium salt having an imidazole ring include 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-propyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-hexyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. From the perspective of the above-mentioned peeling static voltage and step followability, the nitrogen-containing onium salt having an imidazole ring is preferably dialkylimidazolium bis(fluorosulfonyl)imide, and particularly preferably 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide.

Specific examples of alkali metal salts include potassium bis(fluorosulfonyl)imide, lithium bis(fluorosulfonyl)imide, potassium bis(fluoromethanesulfonyl)imide, lithium bis(fluoromethanesulfonyl)imide, potassium bis(trifluoromethanesulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide. Among them, potassium bis(fluorosulfonyl)imide or lithium bis(trifluoromethanesulfonyl)imide is preferred from the perspective of the above-mentioned peeling static voltage and the perspective of step tracking.

The content of the antistatic agent in the adhesive of the present embodiment is preferably 0.1 to 10% by mass, more preferably 0.5 to 8% by mass, particularly preferably 1 to 7% by mass, further preferably 2 to 6% by mass, wherein preferably 2 to 5% by mass, and most preferably 2.9 to 4% by mass. By making the lower limit of the content of the antistatic agent as above, it is easy to meet the value of the above-mentioned peeling static voltage, and the antistatic property is more excellent. In addition, by making the upper limit of the content of the antistatic agent as above, the step tracking property is better.

The adhesive of this embodiment can be any one of acrylic adhesive, polyester adhesive, polyurethane adhesive, rubber adhesive, silicone adhesive, etc. In addition, the adhesive can be any one of emulsion type, solvent type or solvent-free type, and can also be any one of cross-linked type or non-cross-linked type. Among them, acrylic adhesives with excellent adhesive properties, optical properties, etc. are preferred.

The acrylic adhesive may be an active energy ray-curable acrylic adhesive, or an inactive energy ray-curable acrylic adhesive, or a cross-linked acrylic adhesive, or a non-cross-linked acrylic adhesive, or a combination thereof. Among them, inactive energy ray-curable acrylic adhesives are preferred from the perspective of suppressing changes in resistance value. As the inactive energy ray-curable acrylic adhesive, cross-linked acrylic adhesives are particularly preferred, and thermal cross-linked acrylic adhesives are further preferred.

The adhesive constituting the adhesive layer of the present embodiment preferably contains a (meth)acrylate polymer or a crosslinked product thereof, and specifically, preferably is formed by crosslinking an adhesive composition (hereinafter sometimes referred to as "adhesive composition P") containing a (meth)acrylate polymer (A), a crosslinking agent (B) and an antistatic agent (C). In addition, in this specification, (meth)acrylic acid refers to both acrylic acid and methacrylic acid. Other similar terms are also the same. In addition, the concept of "copolymer" is also included in "polymer".

(1) Ingredients

(1-1) (Meth)acrylate polymer (A)

The (meth)acrylate polymer (A) preferably contains a structural unit derived from an alkyl (meth)acrylate. This can provide good adhesiveness. In addition, the hard monomer described below is not contained in the alkyl (meth)acrylate.

From the viewpoint of adhesion, as the alkyl (meth)acrylate, the alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group is preferred. As the alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group, for example, there can be mentioned methyl acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, etc. These can be used alone or in combination of two or more. Among them, from the viewpoint of further improving adhesion, the alkyl (meth)acrylate having 1 to 14 carbon atoms in the alkyl group is preferred, the alkyl (meth)acrylate having 4 to 10 carbon atoms in the alkyl group is more preferred, and the alkyl (meth)acrylate having 5 to 8 carbon atoms in the alkyl group is particularly preferred. Specifically, for example, methyl acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or isooctyl (meth)acrylate is preferred, and 2-ethylhexyl acrylate is particularly preferred.

From the viewpoint of imparting adhesiveness, the (meth)acrylate polymer (A) preferably contains 30 to 95% by mass of structural units derived from an alkyl (meth)acrylate, more preferably 45 to 85% by mass, particularly preferably 55 to 80% by mass, and from the viewpoint of step followability, further preferably 62 to 75% by mass.

The (meth)acrylate polymer (A) preferably has a structural unit derived from a reactive functional group-containing monomer. Thus, the reactive functional group derived from the reactive functional group-containing monomer reacts with the crosslinking agent (B) to form a crosslinked structure (three-dimensional network structure), thereby obtaining an adhesive having a desired cohesive force.

As the reactive group-containing monomer, preferably there can be mentioned a monomer having a hydroxyl group in the molecule (hydroxyl-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl-containing monomer), a monomer having an amino group in the molecule (amino-containing monomer), etc. Among them, a hydroxyl-containing monomer or a carboxyl-containing monomer having excellent reactivity with the crosslinking agent (B) is preferred, and a hydroxyl-containing monomer is more preferred from the viewpoint of suppressing the change in resistance value.

Examples of hydroxyl-containing monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among them, 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate is preferred from the perspective of reactivity with the crosslinking agent (B) and copolymerizability with other monomers. They may be used alone or in combination of two or more.

Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Of these, acrylic acid is preferred from the perspective of reactivity with the crosslinking agent (B) and copolymerizability with other monomers. These may be used alone or in combination of two or more.

The content of the structural unit derived from the reactive functional group-containing monomer in the (meth)acrylate polymer (A) is preferably 1 to 30% by mass, more preferably 3 to 25% by mass, from the viewpoint of cohesive force, and is particularly preferably 5 to 20% by mass, further preferably 10 to 18% by mass, from the viewpoint of suppressing changes in resistance value or the viewpoint of dielectric constant.

The (meth)acrylate polymer (A) preferably contains structural units derived from a hard monomer having a glass transition temperature (Tg) of 70°C or more as a homopolymer. In addition, the above-mentioned reactive functional group-containing monomer is not included in the hard monomer. By making the (meth)acrylate polymer (A) contain structural units derived from the above-mentioned hard monomer, the cohesive force of the obtained adhesive is improved and the durability is excellent. In particular, when containing structural units derived from (meth)acrylates having an alkyl group with 5 to 8 carbon atoms, it is preferred to contain structural units derived from the above-mentioned hard monomer because there is a tendency for the cohesive force to decrease. The glass transition temperature (Tg) of the above-mentioned hard monomer as a homopolymer is preferably 75 to 200°C, particularly preferably 80 to 180°C, and further preferably 90 to 150°C.

Examples of the hard monomer include methyl methacrylate (Tg is 105°C), isobornyl acrylate (Tg is 94°C), isobornyl methacrylate (Tg is 180°C), acryloylmorpholine (Tg is 145°C), adamantyl acrylate (Tg is 115°C), adamantyl methacrylate (Tg is 141°C), dimethylacrylamide (Tg is 89°C), acrylamide (Tg is 165°C), etc. These monomers may be used alone or in combination of two or more thereof.

Among the above-mentioned hard monomers, from the perspective of preventing adverse effects on other properties such as adhesion or transparency and further exerting the performance of the hard monomer, methyl methacrylate, isobornyl acrylate or acryloylmorpholine is more preferred, and isobornyl acrylate as a monomer having an alicyclic structure in the molecule (alicyclic structure-containing monomer) is particularly preferred.

From the viewpoint of cohesive force and durability, the (meth)acrylate polymer (A) preferably contains 0.5 to 30% by mass of structural units derived from the above-mentioned hard monomer, more preferably 1 to 27% by mass, and from the viewpoint of better step followability, particularly preferably 3 to 25% by mass, further preferably 5 to 22% by mass, and among them, preferably 10 to 20% by mass.

The (meth)acrylate polymer (A) also preferably contains a structural unit derived from a monomer having a nitrogen atom in the molecule (nitrogen-containing monomer). In particular, when an alicyclic structure-containing monomer, especially isobornyl acrylate, is used as the hard monomer, it is preferred to contain a structural unit derived from a nitrogen-containing monomer. The presence of a structural unit derived from a nitrogen-containing monomer can impart a predetermined polarity to the adhesive, thereby making the step-following property more excellent.

From the perspective of providing the (meth)acrylate polymer (A) with suitable rigidity, the nitrogen-containing monomer is preferably a monomer having a nitrogen-containing heterocycle. In addition, from the perspective of increasing the degree of freedom of the portion derived from the nitrogen-containing monomer in the high-dimensional structure of the adhesive formed, it is preferred that the nitrogen-containing monomer does not contain a reactive unsaturated double bond group other than one polymerizable group used in the polymerization for forming the (meth)acrylate polymer (A).

As monomers having nitrogen-containing heterocycles, for example, N-(methyl)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(methyl)acryloylpyrrolidone, N-(methyl)acryloylpiperidine, N-(methyl)acryloylpyrrolidine, N-(methyl)acryloylaziridine, (methyl)acrylic acid aziridine ethyl ester, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. can be listed, among which, N-(methyl)acryloylmorpholine having better adhesion is preferred, and N-acryloylmorpholine is particularly preferred. It can be used alone or in combination of two or more.

When the (meth)acrylate polymer (A) contains a structural unit derived from a nitrogen atom-containing monomer, the content is preferably 1 to 20% by mass, more preferably 2 to 17% by mass, particularly preferably 3 to 15% by mass, and further preferably 5 to 12% by mass, from the viewpoint of better step followability.

The (meth)acrylate polymer (A) may contain structural units from other monomers as required. As other monomers, in order not to hinder the action of the hydroxyl-containing monomer, it is preferred that the monomers do not contain a reactive functional group. As such other monomers, for example, (meth)acrylate methoxyethyl, (meth)acrylate ethoxyethyl, (meth)acrylate alkoxyalkyl (meth)acrylate, vinyl acetate, styrene, etc. can be cited. It can be used alone or in combination of two or more.

The (meth)acrylate polymer (A) can be obtained by solution polymerization, can be polymerized in the absence of a solvent, or can be obtained by emulsion polymerization. Among them, a solution polymer obtained by solution polymerization is preferred. Since it is a solution polymer, it is easy to obtain a high molecular weight polymer, and an adhesive with better step tracking properties can be obtained.

The polymerization form of the (meth)acrylate polymer (A) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth)acrylate polymer (A) is preferably 200,000 to 2,000,000, more preferably 300,000 to 1,500,000, particularly preferably 350,000 to 1,200,000, and from the perspective of better step followability, it is further preferably 400,000 to 1,000,000, among which it is preferably 450,000 to 800,000, and most preferably 480,000 to 680,000. In addition, the weight average molecular weight in this specification is a value converted to standard polystyrene measured by gel permeation chromatography (GPC).

In the adhesive composition P, the (meth)acrylate polymer (A) may be used alone or in combination of two or more.

The content of the (meth)acrylate polymer (A) in the adhesive composition P of the present embodiment is preferably 80 to 99.9% by mass, more preferably 90 to 99.5% by mass, particularly preferably 95 to 99% by mass, and further preferably 96.7 to 98% by mass. When the content of the (meth)acrylate polymer (A) is within the above range, good step followability can be obtained.

(1-2) Cross-linking agent (B)

The crosslinking agent (B) can form a good three-dimensional network crosslinking structure by crosslinking the (meth)acrylate polymer (A) by heating the adhesive composition P. This can provide an adhesive having a predetermined cohesive force and having a more excellent step-following property.

The crosslinking agent (B) can react with the reactive functional group (hydroxyl or carboxyl) possessed by the (meth) acrylate polymer (A), for example, isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, hydrazine crosslinking agents, aldehyde crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, ammonium salt crosslinking agents, etc. can be listed. Here, when the (meth) acrylate polymer (A) contains a structural unit from a hydroxyl-containing monomer, as the crosslinking agent (B), an isocyanate crosslinking agent with excellent reactivity with a hydroxyl group is preferably used. In addition, when the (meth) acrylate polymer (A) contains a structural unit from a carboxyl-containing monomer, as the crosslinking agent (B), an epoxy crosslinking agent or a metal chelate crosslinking agent with excellent reactivity with a carboxyl group is preferably used. In addition, the crosslinking agent (B) can be used alone or in combination of two or more.

Isocyanate crosslinking agents at least include polyisocyanate compounds. Examples of polyisocyanate compounds include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and their biuret bodies, isocyanurate bodies, and adducts thereof as reactants with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among them, from the perspective of reactivity with hydroxyl groups, trimethylolpropane-modified aromatic polyisocyanates are preferred, and trimethylolpropane-modified toluene diisocyanate or trimethylolpropane-modified xylene diisocyanate is particularly preferred.

Examples of epoxy crosslinking agents include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, and diglycidylamine. Among them, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane or N,N,N',N'-tetraglycidyl-m-xylenediamine is preferred from the viewpoint of reactivity with carboxyl groups.

Examples of the metal chelate crosslinking agent include chelate compounds whose metal atoms are aluminum, zirconium, titanium, zinc, iron, tin, etc., and aluminum chelate compounds are preferred from the viewpoint of reactivity with the (meth)acrylate polymer (A).

Examples of the aluminum chelate compound include diisopropoxyaluminum monooleyl acetoacetate, monoisopropoxyaluminum bisoleyl acetoacetate, monoisopropoxyaluminum monooleate monoethyl acetoacetate, diisopropoxyaluminum monolauryl acetoacetate, diisopropoxyaluminum monostearyl acetoacetate, diisopropoxyaluminum acetoacetate monoisostearyl acetoacetate, monoisopropoxyaluminum mono-N-lauroyl-β-alanatemonolauryl acetoacetate, aluminum tris(acetylacetonate), aluminum monoacetylacetonate bis(isobutyl acetoacetate) chelate, aluminum monoacetylacetonate bis(2-ethylhexyl acetoacetate) chelate, aluminum monoacetylacetonate bis(lauryl acetoacetate) chelate, and aluminum monoacetylacetonate bis(oleyl acetoacetate) chelate. Among them, aluminum triacetylacetonate is particularly preferred from the viewpoint of reactivity and the ease with which the obtained adhesive can achieve desired adhesive strength.

From the viewpoint of cohesive force, the content of the crosslinking agent (B) in the adhesive composition P is preferably 0.01 to 10 parts by mass, more preferably 0.04 to 5 parts by mass, particularly preferably 0.08 to 1 part by mass, relative to 100 parts by mass of the (meth)acrylate polymer (A). From the viewpoint of better step followability, it is further preferably 0.1 to 0.5 parts by mass, and most preferably 0.12 to 0.2 parts by mass.

(1-3) Antistatic agent (C)

The type of antistatic agent (C) and the content (mass %) of the antistatic agent in the adhesive are as described above. The content of the antistatic agent (C) in the adhesive composition P is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, particularly preferably 1 to 6 parts by mass, and further preferably 2 to 4 parts by mass, relative to 100 parts by mass of the (meth)acrylate polymer (A). By making the content of the antistatic agent within the above range, it is easy to meet the above-mentioned peeling static voltage value, the antistatic property is more excellent, and the step tracking property is better.

(1-4) Silane coupling agent (D)

Adhesive composition P preferably further contains silane coupling agent (D).Thus, when there is a glass member in the adherend, the adhesion of the obtained adhesive and the glass member can be improved.In addition, even if the adherend is a plastic plate, the adhesion of the obtained adhesive and the plastic plate can also be improved.Thus, the step followability of the obtained adhesive is more excellent.In addition, the adhesion to the metal electrodes such as metal wiring is also excellent, and there is a tendency to contribute to the suppression of the resistance value change rate.

As the silane coupling agent (D), an organosilicon compound having good compatibility with the (meth)acrylate polymer (A), light-transmitting properties and having at least one alkoxysilyl group in the molecule is preferred.

Examples of the silane coupling agent (D) include silicon compounds containing polymerizable unsaturated groups such as vinyl trimethoxysilane, vinyl triethoxysilane, and methacryloxypropyl trimethoxysilane; silicon compounds having epoxy structures such as 3-glycidyloxypropyl trimethoxysilane, 3-glycidyloxypropyl methyl diethoxysilane, and 2-(3,4-epoxycyclohexyl) ethyl trimethoxysilane; 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane, and 3-mercaptopropyl trimethoxysilane. Silicon compounds containing mercapto groups such as methoxymethylsilane; Silicon compounds containing amino groups such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; condensates of 3-chloropropyltrimethoxysilane, isocyanatepropyltriethoxysilane, or at least one of them with methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane, etc. Silicon compounds containing alkyl groups, etc., can be used alone or in combination of two or more.

The content of the silane coupling agent (D) in the adhesive composition P is preferably 0.01 to 1 part by mass, more preferably 0.1 to 0.7 part by mass, and particularly preferably 0.2 to 0.5 part by mass, relative to 100 parts by mass of the (meth)acrylate polymer (A).

(1-5) Active energy ray-curable component (E)

The adhesive composition P may further contain an active energy ray-curable component (E). The adhesive containing the active energy ray-curable component (E) has a more excellent step-following property before curing, and the adhesive has a more excellent step-following property after curing.

The active energy ray-curable component (E) is not particularly limited as long as it is a component that is cured by irradiation with active energy rays and can obtain the above-mentioned effects, and can be any one of a monomer, an oligomer or a polymer, or a mixture thereof. Among them, preferably, a multifunctional acrylate monomer having a better step-following property can be cited.

Examples of the multifunctional acrylate monomer include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, adipate neopentyl glycol di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate, dicyclopentyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, di(acryloyloxyethyl) isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl] Difunctional types such as 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(meth)acrylate, tri(acryloyloxyethyl) isocyanurate, ε-caprolactone modified tri-(2-(meth)acryloyloxyethyl) isocyanurate and the like trifunctional types; diglycerol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate and the like tetrafunctional types; propionic acid modified dipentaerythritol penta(meth)acrylate and the like pentafunctional types; dipentaerythritol hexa(meth)acrylate, caprolactone modified dipentaerythritol hexa(meth)acrylate and the like hexafunctional types, etc. Among them, from the perspective of the step tracking property of the obtained adhesive, di(acryloyloxyethyl)isocyanurate, tri(acryloyloxyethyl)isocyanurate, ε-caprolactone-modified tri-(2-(methyl)acryloyloxyethyl)isocyanurate and other multifunctional acrylate monomers containing an isocyanurate structure in the molecule are preferred, and trifunctional or higher multifunctional acrylate monomers containing an isocyanurate structure in the molecule are more preferred, and ε-caprolactone-modified tri-(2-(methyl)acryloyloxyethyl)isocyanurate is particularly preferred. It can be used alone or in combination of two or more. In addition, from the perspective of compatibility with the (methyl)acrylate polymer (A), it is preferred that the molecular weight of the multifunctional acrylate monomer is less than 1000.

From the viewpoint of improving the cohesive force of the obtained adhesive and achieving excellent step followability, the content of the active energy ray-curable component (E) in the adhesive composition P is preferably 1 to 20 parts by mass, particularly preferably 3 to 12 parts by mass, and further preferably 4 to 8 parts by mass, relative to 100 parts by mass of the (meth)acrylate copolymer (A).

(1-6) Various additives

The adhesive composition P may contain various additives commonly used in acrylic adhesives, such as ultraviolet absorbers, tackifiers, antioxidants, light stabilizers, softeners, fillers, refractive index adjusters, etc., as required.

As the ultraviolet absorber, for example, there can be listed compounds such as benzophenone, benzotriazole, benzoate, benzoxazinones, triazines, phenyl salicylate, cyanoacrylate, and nickel complex salts. Among them, it is preferred to use at least one of benzophenone compounds, benzotriazole compounds, and triazine compounds.

Examples of the benzophenone compounds include 2,2-dihydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid hydrate, and 2-hydroxy-4-n-octyloxybenzophenone, among which 2,2-dihydroxy-4-methoxybenzophenone is preferably used. The above ultraviolet absorbers may be used alone or in combination of two or more.

The content of the ultraviolet absorber in the adhesive composition P is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, particularly preferably 1 to 10 parts by mass, and further preferably 2 to 5 parts by mass, based on 100 parts by mass of the (meth)acrylate polymer (A).

When the adhesive composition P contains an active energy ray-curable component (E) and ultraviolet rays are used as active energy rays, it is preferred to contain a photopolymerization initiator. By containing a photopolymerization initiator, the active energy ray-curable component (C) can be efficiently cured, and the polymerization curing time and the amount of ultraviolet rays irradiation can be reduced.

Examples of the photopolymerization initiator 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-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propane-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-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, phenylbis(2,4,6-trimethylbenzoyl)-phosphine oxide, etc. These may be used alone or in combination of two or more.

The content of the photopolymerization initiator in the adhesive composition P is preferably 2 to 20 parts by mass, particularly preferably 4 to 18 parts by mass, and further preferably 6 to 15 parts by mass, based on 100 parts by mass of the active energy ray-curable component (E).

(2) Preparation of adhesive composition

The adhesive composition P can be prepared by preparing a (meth)acrylate polymer (A), mixing the obtained (meth)acrylate polymer (A), a crosslinking agent (B) and an antistatic agent (C), and adding a silane coupling agent (D), an active energy ray-curable component (E), additives, etc. as needed.

The (meth)acrylate polymer (A) can be prepared by polymerizing a mixture of monomers constituting the polymer using a conventional free radical polymerization method. The polymerization of the (meth)acrylate polymer (A) is preferably carried out by a solution polymerization method using a polymerization initiator as required. However, the present invention is not limited thereto, and the polymerization can also be carried out without a solvent. As the polymerization solvent, for example, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc. can be listed, and two or more thereof can also be used simultaneously.

Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more thereof may be used simultaneously. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl azobisisobutyrate, 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), and 2,2'-azobis[2-(2-imidazolin-2-yl)propane].

Examples of the organic peroxide include benzoyl peroxide, tert-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionyl peroxide, and diacetyl peroxide.

Furthermore, in the above-mentioned polymerization step, by adding a chain transfer agent such as 2-mercaptoethanol, the weight average molecular weight of the obtained polymer can be adjusted.

After obtaining the (meth)acrylate polymer (A), a crosslinking agent (B), an antistatic agent (C), and, if necessary, a silane coupling agent (D), an active energy ray-curable component (E), an additive, a diluent solvent, etc. are added to the solution of the (meth)acrylate polymer (A), and the mixture is sufficiently mixed to obtain a solvent-diluted adhesive composition P (coating solution). In addition, for any of the above components, when a solid substance is used, or when precipitation occurs when mixed with other components in an undiluted state, the component may be dissolved alone or diluted in a diluent solvent in advance, and then mixed with other components.

As the above-mentioned dilution solvent, for example, aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and dichloroethane; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; cellosolve-type solvents such as ethyl cellosolve, etc. can be used.

The concentration and viscosity of the coating solution prepared in this way are not particularly limited as long as they are within the range that can be coated, and can be appropriately selected according to the situation. For example, the adhesive composition P is diluted in a manner such that the concentration is 10 to 60% by mass. In addition, when obtaining the coating solution, the addition of a diluting solvent is not a necessary condition. If the adhesive composition P has a coating viscosity, the diluting solvent may not be added. At this time, the adhesive composition P is a coating solution in which the polymerization solvent of the (meth)acrylate polymer (A) is directly used as the diluting solvent.

(3) Manufacture of adhesives

The above adhesive composition P is applied to a desired object and then cross-linked to obtain an adhesive (adhesive layer).

The crosslinking of the adhesive composition P can be performed by heat treatment. The drying treatment after applying the adhesive composition P can also be used as the heat treatment. The heating temperature of the heat treatment is preferably 50 to 150° C., and particularly preferably 70 to 120° C. In addition, the heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

After the heat treatment, a 1-2 week aging period may be provided at room temperature (e.g., 23°C, 50% RH) as required. If the aging period is required, the adhesive is formed after the aging period, and if the aging period is not required, the adhesive is formed after the heat treatment is completed.

The (meth)acrylate polymer (A) is sufficiently crosslinked via the crosslinking agent (B) by the heat treatment (and aging). The pressure-sensitive adhesive layer obtained in this manner can obtain good step-following properties.

In addition, when the adhesive composition P contains an active energy ray-curable component (E), the adhesive composition P can be applied to the desired object as described above and heat-treated, and then the adhesive composition P can be cured by irradiation with active energy rays to form an adhesive (adhesive layer), but it is preferably attached to the adherend in a state before irradiation with active energy rays, and then irradiated with active energy rays. As a result, the step tracking property in the initial stage is more excellent.

(4) Physical properties of adhesive (adhesive layer)

(4-1) Adhesion

The adhesive force of the adhesive sheet of this embodiment to the soda-lime glass is preferably 1 to 100 N/25 mm, more preferably 5 to 60 N/25 mm, particularly preferably 10 to 40 N/25 mm, and further preferably 15 to 35 N/25 mm, wherein preferably 20 to 30 N/25 mm, and most preferably 25 to 27 N/25 mm. If the lower limit of the adhesive force of the adhesive sheet is as above, the step tracking property is more excellent. In addition, if the upper limit of the adhesive force is as above, the step tracking property is well maintained, and the reworkability is excellent.

When the adhesive composition P contains an active energy ray-curable component (E), the adhesive strength after irradiation with active energy rays may satisfy the above-mentioned value. The adhesive strength before irradiation with active energy rays is not particularly limited.

Here, the above-mentioned adhesive strength refers to the adhesive strength measured by the 180-degree peeling method based on JIS Z0237:2009, and the specific test method is shown in the test examples described later.

(4-2) Haze value

The haze value of the adhesive layer of the adhesive sheet of the present embodiment is preferably less than 1%, more preferably less than 0.6%, particularly preferably less than 0.4%, and further preferably less than 0.2%. If the haze value of the adhesive layer is as above, the transparency is very high and suitable for optical applications (display body). On the other hand, the lower limit of the haze value of the adhesive layer is not particularly limited. The lower limit can be 0%, but from the perspective of measurement accuracy, it is usually about 0.1%. Here, the haze value in this specification is set to the value measured according to JIS K7136:2000.

(4-3) Total light transmittance

The lower limit of the total light transmittance of the adhesive layer of the adhesive sheet of the present embodiment is preferably 70% or more, preferably 80% or more, particularly preferably 90% or more, and more preferably 99% or more. By making the total light transmittance of the adhesive layer as described above, the visibility as a display body becomes good. On the other hand, the upper limit of the total light transmittance of the adhesive layer is not particularly limited, but is usually 100% or less. Here, the total light transmittance of this specification is set to the value measured according to JIS K7361-1:1997.

(4-4) Surface resistivity

Under the environment of 23°C and 50% RH, a voltage of 100V is applied to the adhesive sheet (adhesive layer/peel sheet) of the present embodiment for 10 seconds. The upper limit of the surface resistivity of the exposed surface of the adhesive layer at this time is preferably 1.0×10 ¹³ Ω/sq or less, more preferably 5.0×10 ¹² Ω/sq or less, particularly preferably 1.0×10 ¹² Ω/sq or less, further preferably 5.0×10 ¹¹ Ω/sq or less, wherein preferably 2.0×10 ¹¹ Ω/sq or less. By setting the upper limit of the surface resistivity to the above, excellent antistatic properties can be exerted, and the above-mentioned peeling static voltage can be easily satisfied. The lower limit of the surface resistivity is not particularly limited, but is generally preferably 1.0×10 ⁵ Ω/sq or more, particularly preferably 1.0×10 ⁶ Ω/sq or more, and further preferably 1.0×10 ⁷ Ω/sq or more. The surface resistivity of the adhesive layer was measured in accordance with JIS K6911:2006, and specifically, as shown in the test examples described below.

(4-5) Volume resistivity

When a voltage of 100 V is applied to the adhesive sheet (adhesive layer/release sheet) of the present embodiment for 10 seconds under an environment of 23° C. and 50% RH, the upper limit of the volume resistivity of the adhesive layer is preferably 1.0×10 ¹² Ω/sq or less, more preferably 1.0×10 ¹¹ Ω/sq or less, and particularly preferably 5.0

×10 ¹⁰ Ω/sq or less, more preferably 1.0×10 ¹⁰ Ω/sq or less, preferably 5.0×10 ⁹ Ω/sq or less, and most preferably 1.8×10 ⁹ Ω/sq or less. By setting the upper limit of the volume resistivity to the above, excellent antistatic properties can be exerted and the above-mentioned peeling static voltage can be easily satisfied. The lower limit of the volume resistivity is not particularly limited, but is generally preferably 1.0×10 ⁵ Ω/sq or more, particularly preferably 1.0×10 ⁶ Ω/sq or more, and further preferably 1.0×10 ⁷ Ω/sq or more. In addition, the volume resistivity of the adhesive layer is measured in accordance with JIS K6911:2006, specifically, as shown in the test examples described later.

(4-6) Resistance value change rate

Generally, when a conductive layer and an adhesive layer are stacked in a state of contact with each other and placed under a durable condition, an increase in the resistance value of the conductive layer is observed. However, although the reason is not clear, the adhesive layer of this embodiment can suppress this increase in resistance value to a minimum.

Specifically, an adhesive layer of the present embodiment is attached to a glass plate, and a conductive layer (for example, a transparent conductive film formed by tin-doped indium oxide (ITO)) is stacked on the surface of the adhesive layer opposite to the surface in contact with the glass plate. A substrate (for example, a polyethylene terephthalate film) for retaining the conductive layer is arranged on the surface of the conductive layer opposite to the surface in contact with the adhesive layer. This glass plate/adhesive layer/conductive layer/substrate structure is placed under wet heat conditions of 85°C and 85% RH for 500 hours (durability test), and the resistance value of the conductive layer before and after durability is measured. At this time, the ratio of the resistance value after durability to the resistance value before durability (resistance value change rate: (resistance value after durability/resistance value before durability) × 100) is preferably 300% or less, more preferably 200% or less, particularly preferably 150% or less, and further preferably 130% or less. On the other hand, the lower limit of the above-mentioned resistance value change rate is not particularly limited and is about 1%. In the above test, a substrate was used as a member for holding the conductive layer, but it is estimated that the same results would be obtained even if the member was a glass plate or a resin plate. The detailed test method of the resistance value change rate is shown in the test examples described below.

(4-7) Dielectric constant

The dielectric constant of the adhesive of this embodiment at 0.1 MHz is preferably 2.0 to 14.0, more preferably 4.0 to 12.0, particularly preferably 5.0 to 10.0, further preferably 6.0 to 9.0, and particularly preferably 7.0 to 8.0. By setting the dielectric constant within the above range, excellent antistatic properties can be exhibited, and the above peeling static voltage can be easily satisfied.

(4-8) Step-by-step following rate

The step following rate (%) of the adhesive layer of the present embodiment represented by the following formula is preferably 10 to 80%, preferably 20 to 70%, particularly preferably 30 to 60%, and further preferably 40 to 50%.

Step following rate (%) = {(height of the step that remains embedded without floating, peeling, etc. after the specified durability test (μm))/(thickness of the adhesive layer)}×100

The test method of the step follow-up rate is as shown in the test example described later.

(5) Specific composition of adhesive sheet

FIG. 1 shows a specific structure of an example of the adhesive sheet according to the present embodiment.

As shown in Fig. 1, an adhesive sheet 1 of one embodiment is composed of two release sheets 12a, 12b and an adhesive layer 11, and the adhesive layer 11 is sandwiched by the two release sheets 12a, 12b in a manner of contacting the release surfaces of the two release sheets 12a, 12b. In addition, the release surface of the release sheet in this specification refers to the surface of the release sheet that has release properties, and also includes any one of the surfaces that have been subjected to release treatment and the surfaces that show release properties even if no release treatment is applied.

The release sheets 12a and 12b protect the adhesive layer until the adhesive sheet is used, and are peeled off when the adhesive sheet (adhesive layer) is used. In the adhesive sheet 1 of the present embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

As the peeling sheets 12a and 12b, for example, polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene-(methyl) acrylic acid copolymer film, ethylene-(methyl) acrylic acid ester polymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. can be used. In addition, crosslinked films of these films can also be used. Further, laminated films of these films can also be used.

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

Although there is no particular limitation on the thickness of the release sheets 12a and 12b, it is generally about 20 to 150 μm.

Among the release sheets 12a and 12b, one is preferably a heavy release type release sheet with a large release force, and the other is preferably a light release type release sheet with a small release force. In particular, since the thickness of the adhesive layer of this embodiment is relatively thin, the operability is likely to deteriorate, so it is preferred that the two release sheets 12a and 12b each have a predetermined release force, and it is preferred that there is a predetermined release force difference between the two release sheets 12a and 12b.

The peeling force when peeling the light release type release sheet from the adhesive layer of this embodiment is preferably 10 to 150 mN/25 mm, more preferably 30 to 120 mN/25 mm, particularly preferably 50 to 100 mN/25 mm, and further preferably 60 to 80 mN/25 mm.

The peeling force when the heavy-release release sheet is peeled off from the adhesive layer of this embodiment is preferably 20 to 300 mN/25 mm, more preferably 50 to 200 mN/25 mm, particularly preferably 90 to 150 mN/25 mm, and further preferably 105 to 125 mN/25 mm.

The difference in peel force between the light release type release sheet and the heavy release type release sheet is preferably 5 to 150 mN/25 mm, more preferably 20 to 100 mN/25 mm, particularly preferably 40 to 70 mN/25 mm, and further preferably 44 to 52 mN/25 mm.

By making the respective peeling forces and the peeling force difference within the above range, the so-called blocking (weeping separation) can be suppressed when the light release type release sheet is peeled off, and the light release type release sheet can be peeled off smoothly without peeling the adhesive layer from the heavy release type release sheet. In addition, the accidental peeling of each release sheet can be suppressed, and the heavy release type release sheet can be peeled off well.

Here, the peeling force is basically a peeling force measured by a 180-degree peeling method in accordance with JIS Z0237:2009, and the specific test method is shown in the test examples described later.

(6) Manufacturing of adhesive sheets

As a manufacturing example of the adhesive sheet 1, a coating liquid of the adhesive composition P is applied to the release surface of a release sheet 12a (or 12b) and heat-treated to thermally cross-link the adhesive composition P. After forming a coating layer, the release surface of another release sheet 12b (or 12a) is superimposed on the coating layer. When a maturation period is required, the coating layer becomes the adhesive layer 11 by setting the maturation period. When a maturation period is not required, the coating layer directly becomes the adhesive layer 11. Through the above process, the adhesive sheet 1 can be obtained. The conditions for the heat treatment and maturation are as described above.

As a method for applying the coating liquid 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, etc. can be utilized.

[Display Body]

A display according to one embodiment of the present invention comprises one display component, another display component, and an adhesive layer for bonding the one display component and the other display component to each other. The adhesive layer is formed of the adhesive layer of the adhesive sheet according to the above embodiment.

At least one of the above-mentioned one display body component and the other display body component may have a step difference on at least one side of the surface bonded by the above-mentioned adhesive layer. The adhesive layer of this embodiment has excellent step difference tracking property, so even under high temperature and high humidity conditions, it can also suppress the occurrence of floating, peeling, etc. near the step difference.

The one display body component and the other display body component may both be hard plates. When the two hard plates are bonded to each other, since the hard plates are hard and do not bend, the two hard plates are squeezed in a vertical direction with the adhesive layer attached to one hard plate, thereby making each hard plate fit closely with the adhesive layer, thereby bonding the two hard plates to each other. By making the gel fraction of the adhesive within the above range, the adhesive layer of the present embodiment can bond the two hard plates well in the above bonding method.

A display according to an embodiment of the present invention will be described with reference to the drawings.

As shown in Figure 2, the display body 2 of this embodiment is composed of a first display body constituent member 21 (one display body constituent member), a second display body constituent member 22 (another display body constituent member) and an adhesive layer 11, wherein the adhesive layer 11 is located between the first display body constituent member 21 and the second display body constituent member 22, and adheres the first display body constituent member 21 and the second display body constituent member 22 to each other.

At least one of the first display component 21 and the second display component 22 may have a step at least on the surface to be bonded to the adhesive layer 11. In the present embodiment shown in FIG2 , the first display component 21 has a step such as a printed layer 3 on the surface on the adhesive layer 11 side.

The adhesive layer 11 in the display 2 is the adhesive layer 11 of the adhesive sheet 1 or a layer obtained by curing the adhesive layer 11 of the adhesive sheet 1 by irradiation with active energy rays.

Examples of the display 2 include a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescent (organic EL) display, and electronic paper, and may also be a touch panel.

The first display component 21 is preferably a protective panel composed of a laminate including a glass plate, a plastic plate, etc. In addition to being a glass plate, a plastic plate, etc., the printed layer 3 is usually formed in a frame shape on the adhesive layer 11 side of the first display component 21 .

The glass plate is not particularly limited, and examples thereof include 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. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

The plastic plate is not particularly limited, and examples thereof include acrylic plates, polycarbonate plates, etc. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

In addition, various functional layers (transparent conductive film, metal layer, silicon dioxide layer, hard coating layer, anti-glare layer, etc.) may be provided on one or both sides of the glass plate or plastic plate, and optical components may be laminated. In addition, the transparent conductive film and the metal layer may also be patterned.

The second display component 22 is preferably an optical component to be attached to the first display component 21, a display module (for example, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescent (organic EL) module, etc.), an optical component that is a part of the display module, or a stacked body containing a display module.

As the optical member, for example, anti-scattering film, polarizing plate (polarizing film), polarizer, phase difference plate (phase difference film), viewing angle compensation film, brightness improvement film, contrast improvement film, liquid crystal polymer film, diffusion film, semi-transmissive reflection film, transparent conductive film, etc. As the transparent conductive film, for example, an ITO-PET film having a tin-doped indium oxide (ITO) layer formed on one side of a polyethylene terephthalate film can be preferably cited.

The material constituting the printed layer 3 is not particularly limited, and a known material for printing can be used.

The thickness of the printed layer 3, i.e., the height of the step is preferably 0.5 to 50 μm, more preferably 1 to 30 μm, and particularly preferably 3 to 20 μm. By making the thickness of the printed layer 3 within the above range, the step tracking property brought by the adhesive layer 11 can be effectively exerted, and the concealment of the printed layer 3 as the target can be fully ensured. In addition, the printed layer 3 is usually formed in a frame shape on the adhesive layer 11 side of the display body component.

In order to manufacture the display 2, as an example, one release sheet 12a of the adhesive sheet 1 is peeled off, and the adhesive layer 11 exposed by the adhesive sheet 1 is attached to the surface of the first display component 21 on the side where the printed layer 3 exists. At this time, the adhesive layer 11 formed of the adhesive with a controlled gel fraction has excellent initial step tracking properties, so that the generation of gaps or floating near the step caused by the printed layer 3 can be suppressed.

Next, another peeling sheet 12b is peeled off from the adhesive layer 11 of the adhesive sheet 1, and the adhesive layer 11 exposed by the adhesive sheet 1 is bonded to the second display body component 22, thereby obtaining a display body. In addition, as another example, the bonding order of the first display body component 21 and the second display body component 22 can also be replaced.

Here, when the adhesive composition P contains an active energy ray-curable component (E), it is preferred that after the laminate of the first display body constituent member 21 and the adhesive layer 11 is attached to the second display body constituent member 22, the adhesive layer 11 is irradiated with active energy rays through the first display body constituent member 21 and/or the second display body constituent member 22 to cure the adhesive layer 11. Thus, the step followability is further improved.

The active energy ray refers to an active energy ray having an energy quantum among electromagnetic waves or charged particle beams, and specific examples thereof include ultraviolet rays, electron beams, etc. Among the active energy rays, ultraviolet rays are particularly preferred because they are easy to handle.

Ultraviolet irradiation can be performed using a high pressure mercury lamp, a fusion H lamp, a xenon lamp, etc., and the ultraviolet irradiation amount is preferably about 50 to 1000 mW/cm ² in terms of illuminance. In addition, the light amount is preferably 50 to 10000 mJ/cm ² , more preferably 80 to 5000 mJ/cm ² , and particularly preferably 300 to 2000 mJ/cm ^2. On the other hand, electron beam irradiation can be performed using an electron beam accelerator, etc., and the electron beam irradiation amount is preferably about 10 to 1000 krad.

In the above-mentioned display body 2, since the adhesive layer 11 has excellent step tracking properties under high temperature and high humidity conditions, even when the display body 2 is placed under high temperature and high humidity conditions (for example, 85°C, 85% RH, 500 hours), floating, peeling, etc. near the step can be suppressed.

The adhesive layer 11 has excellent antistatic properties, so when, for example, the protective film attached to the surface (exposed surface) of the first display component 21 (protective panel) is peeled off from the first display component 21, static electricity can be well suppressed. As a result, it is possible to suppress the occurrence of adverse conditions caused by static electricity in the components inside the display 2. As a specific example, it is possible to suppress the degradation or destruction of electrodes formed by ITO, the adverse conditions of poor responsiveness of the touch panel (slow or no response, etc.), etc.

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 embodiments also includes all design changes or equivalents within the technical scope of the present invention.

For example, any one or two of the release sheets 12a and 12b in the adhesive sheet 1 can be omitted, and in addition, the required optical components can be stacked to replace the release sheets 12a and/or 12b. In addition, the first display component 21 may not have a step difference. Further, not only the first display component 21 may have a step difference on the adhesive layer 11 side, but the second display component 22 may also have a step difference on the adhesive layer 11 side.

In addition, in this specification, unless otherwise specified, the term "X to Y" (X and Y are arbitrary numbers) means "X or more and Y or less", and also includes the meaning of "preferably greater than X" or "preferably less than Y". In addition, unless otherwise specified, the term "X or more" (X is an arbitrary number) means "preferably greater than X", and unless otherwise specified, the term "Y or less" (Y is an arbitrary number) means "preferably less than Y".

Example

Hereinafter, the present invention will be described in more detail using examples and the like, but the scope of the present invention is not limited to these examples and the like.

[Example 1]

1. Preparation of (meth)acrylate polymers

60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized by solution polymerization to prepare a (meth)acrylate polymer (A). The molecular weight of the (meth)acrylate polymer (A) was measured by the method described below, and the weight average molecular weight (Mw) was 700,000.

2. Preparation of adhesive composition

100 parts by mass (solid content conversion value; the same below) of the (meth)acrylate polymer (A) obtained in the above step 1, 0.25 parts by mass of an isocyanate crosslinking agent (B1; manufactured by Mitsui Chemicals, Inc., product name "TAKENATE D-101E"), 1.0 parts by mass of 4-methyl-1-octylpyridinium bis(fluorosulfonyl)imide (C1) as an antistatic agent (C), and 0.25 parts by mass of 3-glycidyloxypropyltrimethoxysilane as a silane coupling agent (D) were mixed, stirred thoroughly, and diluted with methyl ethyl ketone to obtain a coating solution of an adhesive composition.

Here, each ratio (solid content conversion value) of the adhesive composition when the (meth)acrylate polymer (A) is set to 100 parts by mass (solid content conversion value) is shown in Table 1. In addition, the details of the abbreviations and the like described in Table 1 are as follows.

[(Meth)acrylate polymer (A)]

2EHA: 2-Ethylhexyl acrylate

MMA: Methyl Methacrylate

HEA: 2-Hydroxyethyl Acrylate

BA: n-butyl acrylate

MA: Methyl acrylate

IBXA: Isobornyl acrylate

ACMO: N-acryloylmorpholine

EA: Ethyl acrylate

AA: Acrylic acid

[Crosslinking agent (B)]

B1: Isocyanate crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "TAKENATE D-101E")

B2: Aluminum triacetylacetonate (manufactured by Soken Chemical & Engineering Co., Ltd., product name "M-5A")

[Antistatic agent (C)]

C1: 4-methyl-1-octylpyridinium bis(fluorosulfonyl)imide (ionic liquid)

C2: Lithium bis(trifluoromethanesulfonyl)imide (ionic solid)

C3: Tri-n-butylmethylammonium bis(trifluoromethanesulfonyl)imide (ionic liquid)

3. Manufacturing of adhesive sheet

The coating solution of the adhesive composition obtained in the above step 2 was applied to the release-treated surface of a heavy-release release sheet (manufactured by LINTEC Corporation, product name "SP-PET752150") having one side of a polyethylene terephthalate film subjected to release treatment using a silicone release agent using a knife coater. The coating layer was then heated at 90° C. for 1 minute to form a coating layer.

Next, the coating layer on the heavy release type release sheet obtained above was laminated to a light release type release sheet (manufactured by LINTEC Corporation, product name "SP-PET382120") having a single surface of a polyethylene terephthalate film subjected to release treatment using a silicone release agent, with the release-treated surface of the light release type release sheet in contact with the coating layer, and aged for 7 days under the conditions of 23° C. and 50% RH, thereby preparing an adhesive sheet consisting of a heavy release type release sheet/adhesive layer (thickness: 25 μm)/light release type release sheet. The thickness of the adhesive layer is a value measured in accordance with JIS K7130 using a constant pressure thickness gauge (manufactured by TECLOCK, product name "PG-02").

4. Manufacturing of laminated body

4-1. Preparation of substrate

As a coating solution for forming a hard coat layer, 100 parts by mass (indicated as solid content conversion value; hereinafter, the same applies to other components) of a polyfunctional (meth)acrylate (manufactured by SHIN-NAKAMURA CHEMICAL Co., Ltd., product name "NK ESTER A-DPH"), 4.3 parts by mass of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator, 11 parts by mass of silica fine particles (manufactured by FUJI SILYSIA CHEMICAL LTD., product name "SYLOPHOBIC 702", average particle size 4.1 μm), 0.01 parts by mass of a leveling agent (manufactured by Dow Corning Toray Co., Ltd., product name "SH28"), and 8.3 parts by mass of silica nanoparticles (manufactured by Nissan Chemical Corporation, product name "MIBK-ST", average particle size: 10 nm) were mixed, and diluted with propylene glycol monomethyl ether to prepare a coating solution with a solid content concentration of 30%.

The coating solution was applied to one side of a polyethylene terephthalate (PET) film (manufactured by TORAY INDUSTRIES, INC., product name "125-U403", thickness 125 μm) using a Meyer rod #10, and dried at 70°C for 1 minute. Then, ultraviolet irradiation was performed using a high-pressure mercury lamp in a nitrogen atmosphere at an illumination of 200 mW/cm ² and a light quantity of 300 mJ/cm ² to form a hard coating layer (acrylic hard coating layer) with a thickness of 1.5 μm. The PET film with a hard coating layer (tensile elastic modulus: 5.0 GPa, haze value: 4.0%) obtained in this manner was used as a substrate.

4-2. Preparation of protective film

A (meth)acrylate polymer was prepared by copolymerizing 65 parts by mass of 2-ethylhexyl acrylate, 25 parts by mass of n-butyl acrylate, and 10 parts by mass of 4-hydroxybutyl acrylate by solution polymerization. The molecular weight of the (meth)acrylate polymer was measured by the method described below, and the weight average molecular weight (Mw) was 1.2 million.

100 parts by mass (solid content conversion value; the same below) of the (meth)acrylate polymer obtained above, 0.72 parts by mass of an isocyanurate crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "TAKENATE D-170N"), and 1.0 parts by mass of potassium hexafluorophosphate were mixed, stirred thoroughly, and diluted with toluene to obtain a coating solution of an adhesive composition.

The coating solution of the adhesive composition obtained above was applied to one side of a polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Corporation, product name "DIAFOIL T100", thickness 38 μm) using a knife coater. The coating layer was then heat treated at 90° C. for 1 minute to form a coating layer. The coating layer was then aged for 14 days at 23° C. and 50% RH to form an adhesive layer (acrylic adhesive layer) having a thickness of 15 μm. The PET film with an adhesive layer obtained in this manner was used as a protective film.

4-3. Production of laminated body

The protective film obtained in the above step 4-2 is attached to the hard coating layer of the substrate obtained in the above step 4-1 via the adhesive layer of the protective film. Next, the light release type release sheet is peeled off from the adhesive sheet obtained in the above step 3, and the exposed adhesive layer is attached to the PET film of the above substrate. In this way, a first laminate consisting of protective film/substrate/adhesive layer/heavy release type release sheet is obtained.

The heavy peeling type peeling sheet is peeled off from the adhesive layer of the first laminate obtained above to obtain a second laminate consisting of a protective film/substrate/adhesive layer. The second laminate is attached to the ITO layer side of soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd., thickness: 1.1 mm), soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd., thickness: 0.7 mm), and a transparent conductive film (manufactured by OIKE & Co., Ltd., a laminate of PET film and ITO layer (ITO-PET film), total thickness 125 μm). Then, a heat treatment is performed at 50°C and 0.5 MPa for 30 minutes, and placed at normal pressure, 23°C, and 50% RH for 24 hours. In this manner, a laminated body was obtained by laminating the second laminated body (the substrate in the second laminated body corresponds to the first display body constituent member) and the glass plate (1.1 mm/0.7 mm) or the ITO-PET film (the second display body constituent member).

[Examples 2 to 17, Comparative Examples 1 to 7]

An adhesive sheet and a laminate were produced in the same manner as in Example 1, except that the types and ratios of the monomers constituting the (meth)acrylate polymer (A), the type and blending amount of the crosslinking agent (B), the type and blending amount of the antistatic agent (C), and the thickness of the adhesive layer were changed as shown in Table 1.

In Example 4, 3.0 parts by mass of 2,2-dihydroxy-4-methoxybenzophenone (manufactured by SOLVAY, product name: "CYASORB UV-24") was further blended into the adhesive composition as a UV absorber.

In Example 15 and Comparative Example 6, 5.0 parts by mass of ε-caprolactone-modified tris-(2-acryloyloxyethyl)isocyanurate as an active energy ray-curable component (E) and 0.5 parts by mass of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as a photopolymerization initiator were further blended.

In Example 15 and Comparative Example 6, the adhesive layer of the laminated body produced in the same manner as in Example 1 was irradiated with active energy rays (ultraviolet rays) through the protective film and the substrate under the following conditions to cure the adhesive layer.

＜Active energy ray irradiation conditions＞

Use high pressure mercury lamp

·Illuminance is 200mW/cm ² , light intensity is 1000mJ/cm ²

· UV illuminance-light meter used was "UVPF-A1" manufactured by EYE GRAPHICS Co., Ltd.

Here, the weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured under the following conditions using gel permeation chromatography (GPC) (GPC measurement).

<Measurement conditions>

·Measurement device: HLC-8320 manufactured by TOSOH CORPORATION

·GPC columns (passed in the following order): manufactured by TOSOH CORPORATION

TSK gel superH-H

TSK gel superHM-H

TSK gel superH2000

·Test solvent: tetrahydrofuran

·Measurement temperature: 40℃

[Test Example 1] (Measurement of gel fraction)

The adhesive sheets prepared in the examples and comparative examples were cut into a size of 80 mm x 80 mm, and the adhesive layer was wrapped in a polyester mesh (mesh size 200), and the mass was weighed with a precision balance, and the mass of the adhesive itself was calculated by subtracting the mass of the mesh alone. The mass at this time was recorded as M1.

Next, at room temperature (23°C), immerse the adhesive coated in the polyester mesh in ethyl acetate for 24 hours. Then take out the adhesive, air-dry it for 24 hours at a temperature of 23°C and a relative humidity of 50%, and further dry it in an oven at 80°C for 12 hours. After drying, weigh its mass with a precision balance, subtract the mass of the above-mentioned mesh alone, and calculate the mass of the adhesive itself. The mass at this time is recorded as M2. The gel fraction (%) is expressed as (M2/M1)×100. The results are shown in Table 2.

In addition, the gel fraction was measured after the adhesive layer was irradiated with active energy rays (ultraviolet rays; UV) through the light release type release sheet for the adhesive sheets of Example 15 and Comparative Example 6. The irradiation conditions of the active energy rays are as follows.

＜Active energy ray irradiation conditions＞

Use high pressure mercury lamp

·Illuminance is 200mW/cm ² , light intensity is 1000mJ/cm ²

· UV illuminance-light meter used was "UVPF-A1" manufactured by EYE GRAPHICS Co., Ltd.

[Test Example 2] (Measurement of Haze Value)

The adhesive layer of the adhesive sheet manufactured in the embodiment and the comparative example was bonded to glass, which was used as a sample for measurement. Based on the background measurement using glass, the haze value (%) of the above-mentioned sample for measurement was measured using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., Ltd., product name "NDH-5000") in accordance with JIS K7361-1:2000. The results are shown in Table 2.

[Test Example 3] (Measurement of total light transmittance)

The adhesive layer of the adhesive sheet manufactured in the embodiment and the comparative example was bonded to glass to serve as a sample for measurement. Based on the background measurement using glass, the total light transmittance (%) of the sample for measurement was measured using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., Ltd., product name "NDH-5000") in accordance with JIS K7361-1:1997.

The results are shown in Table 2.

[Test Example 4] (Measurement of Adhesion Strength)

The light release type release sheet was peeled off from the adhesive sheet produced in the examples and comparative examples, and the exposed adhesive layer was attached to the easy adhesive layer of a polyethylene terephthalate (PET) film (manufactured by TOYOBO CO., LTD., product name "PET A4300", thickness: 100 μm) having an easy adhesive layer to obtain a laminate of a heavy release type release sheet/adhesive layer/PET film. The obtained laminate was cut into 25 mm wide and 100 mm long, and used as a sample.

Under the environment of 23°C and 50%RH, the heavy peeling type peeling sheet was peeled off from the above sample, and the exposed adhesive layer was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.), and then pressurized at 0.5MPa and 50°C for 20 minutes using an autoclave manufactured by KURIHARA SEISAKUSHO Co., Ltd. Then, after being placed under the environment of 23°C and 50%RH for 24 hours, a tensile tester (ORIENTEC Co., LTD., TENSILON) was used to measure the adhesion (N/25mm) at a peeling speed of 300mm/min and a peeling angle of 180 degrees. The conditions not described here were measured in accordance with JIS Z0237:2009. The results are shown in Table 2.

In addition, the adhesive sheets of Example 15 and Comparative Example 6 were attached to soda lime glass in the same manner as above and pressurized by an autoclave, and then the adhesive layer was irradiated with active energy rays (ultraviolet rays; UV) through the PET film, and then the adhesive strength after standing for 24 hours was measured in the same manner as above. The irradiation conditions of active energy rays were the same as those in Test Example 1.

[Test Example 5] (Measurement of Peel Force)

For the adhesive sheets manufactured in the embodiments and comparative examples, samples (heavy peeling type release sheet/adhesive layer/PET film) were prepared in the same manner as in Test Example 4. The PET film side of the sample was adhered to a stainless steel plate using a double-sided adhesive tape and fixed to a universal tensile testing machine (manufactured by ORIENTEC Co., LTD., product name "TENSILON UTM-4-100"). Under the conditions of a temperature of 23°C and 50% RH, the heavy peeling type release sheet of the sample was stretched in a 180° direction at a tensile speed of 300mm/min in accordance with JIS Z0237:2009, and the force when the heavy peeling type release sheet was peeled off from the adhesive layer was measured, and it was used as the peeling force (heavy surface peeling force; mN/25mm). The results are shown in Table 2.

In addition, the adhesive sheet manufactured in the embodiment and the comparative example was cut into 25 mm wide and 100 mm long, and used as a sample. The heavy peeling type peeling sheet side of the sample was attached to a stainless steel plate using a double-sided adhesive tape and fixed to a universal tensile testing machine (manufactured by ORIENTEC Co., LTD., product name "TENSILON UTM-4-100"). For this sample, the peeling force (light side peeling force; mN/25mm) when the light peeling type peeling sheet is peeled off from the adhesive layer was measured in the same manner as above. The results are shown in Table 2.

The peel force difference was calculated by subtracting the light side peel force from the heavy side peel force obtained above.

[Test Example 6] (Measurement of surface resistivity)

The light peelable release sheet was peeled off from the adhesive sheet manufactured in the embodiment and the comparative example, and the surface resistivity of the adhesive surface of the exposed adhesive layer was measured according to JIS K6911:2006. Specifically, the surface resistivity (Ω/sq) of the adhesive surface of the adhesive layer after applying a voltage of 100 V for 10 seconds to the adhesive sheet (100 mm×100 mm) from which the light peelable release sheet was peeled was measured using a resistivity meter (manufactured by Mitsubishi Chemical Analytech, Co., Ltd., product name "Hiresta UPMCP-HT450 type") under an environment of 23°C and 50% RH. The results are shown in Table 2.

[Test Example 7] (Measurement of volume resistivity)

The light peeling type release sheet is peeled off from the adhesive sheet manufactured in the embodiment and the comparative example, and the adhesive surface of the exposed adhesive layer is attached to the processing table for measurement of the resistivity meter (Mitsubishi Chemical Analytech, Co., Ltd., product name "Hiresta UP MCP-HT450"). Next, the heavy peeling type release sheet is peeled off and used as a measurement sample. For the measurement sample, the volume resistivity is measured in accordance with JIS K6911:2006. Specifically, under an environment of 23°C and 50% RH, the above-mentioned resistivity meter is used to measure the volume resistivity (Ω/sq) of the adhesive layer after applying a voltage of 100V to the adhesive layer (100mm×100mm) for 10 seconds. The results are shown in Table 2.

[Test Example 8] (Calculation of dielectric constant)

In the same manner as in the examples and comparative examples, a 100 μm thick adhesive layer was formed on one side of a 50 μm thick polyethylene terephthalate film, and a 50 μm thick polyethylene terephthalate film was bonded to the adhesive layer, followed by cutting into 50 mm×50 mm.

The obtained laminate was measured for electrostatic capacitance (C1) at a measurement frequency of 0.1 MHz using an impedance analyzer (manufactured by Japan Hewlett-Packard Company, "HP-4194A"). In addition, two sheets of the above-mentioned polyethylene terephthalate film with a thickness of 50 μm were overlapped and cut into 50 mm×50 mm, and the electrostatic capacitance (C2) was measured in the same manner. Then, the electrostatic capacitance (C3) of the adhesive was calculated based on the following calculation formula for series capacitors according to the values of C1 and C2.

1/C1＝1/C2+1/C3

Based on the electrostatic capacitance C3, the dielectric constant εs of the adhesive was calculated by the following mathematical formula. The results are shown in Table 2.

εs＝(C3×d)/(ε0×S)

εs: Dielectric constant of adhesive

ε0: Dielectric constant of vacuum (8.854×10 ^-12 )

C3: Electrostatic capacitance of adhesive

S: Area of adhesive layer

d: Thickness of adhesive layer

[Test Example 9] (Measurement of resistance value)

The light peeling type peeling sheet is peeled off from the adhesive sheet manufactured in the embodiment and the comparative example, and the exposed adhesive layer is attached to a glass plate (soda lime glass, thickness 1.1mm). Then, the heavy peeling type peeling sheet is peeled off from the above-mentioned adhesive layer to expose the adhesive layer, and a transparent conductive film (manufactured by OIKE&Co., Ltd., a laminate of PET film and ITO layer (ITO-PET film), with a total thickness of 125μm) is laminated in a manner that the ITO layer side is in contact with the above-mentioned adhesive layer to obtain a sample. For this sample, a non-contact resistance measuring instrument (manufactured by NAPSON CORPORATION, product name "EC-80") is used to measure the resistance value (Ω/sq; before durability) of the transparent conductive layer. The results are shown in Table 2.

Furthermore, the sample was placed in a wet heat condition of 85°C and 85%RH for 500 hours (durability test), and the resistance value (Ω/sq; after durability) of the transparent conductive layer after the durability test was measured in the same manner as above.

Next, the resistance change rate (%; (resistance value after durability/resistance value before durability)×100) which is the ratio of the resistance value after durability to the resistance value before durability was calculated, and the resistance change was evaluated based on the following criteria.

◎…Resistance value change rate is less than 150%

〇…The resistance value change rate is greater than 150% and less than 300%

×…Resistance value change rate is greater than 300%

[Test Example 10] (Measurement of peeling static voltage)

The protective film was peeled off from the substrate of the three laminates (25 mm × 100 mm) prepared in the examples and comparative examples by manual operation at a peeling speed of 2.0 m/min. After peeling for 2 seconds, the electrostatic potential (peeling electrostatic voltage; kV) at a position 2.0 cm away from the exposed surface of the glass plate or ITO-PET film was measured using an electrostatic measuring device (manufactured by SIMCO JAPAN., product name "FMX-003"). The results are shown in Table 2.

[Test Example 11] (Measurement of step followability)

Ultraviolet curing ink (manufactured by Teikoku Printing Inks Mfg. Co., Ltd., product name "POS-911BLACK") was screen-printed on the surface of a glass plate (manufactured by NSG Precision, product name "Corning glass EAGLE XG", 90 mm in length × 50 mm in width × 0.5 mm in thickness) in a frame shape (outer shape: 90 mm in length × 50 mm in width, 5 mm in width). Then, ultraviolet rays were irradiated (80 W/ ^cm2 , 2 metal halide lamps, lamp height 15 cm, conveyor speed 10 to 15 m/min) to cure the printed ultraviolet curing ink, thereby manufacturing a stepped glass plate having a step caused by printing (the height of the step: any one of 1 μm, 5 μm, 10 μm, 20 μm, 40 μm, and 60 μm).

The light peeling type release sheet was peeled off from the adhesive sheet manufactured in the embodiment and the comparative example, and the exposed adhesive layer was bonded to the easy adhesive layer of the polyethylene terephthalate (PET) film (manufactured by TOYOBO CO., LTD., product name "PET A4300", thickness: 100 μm) having an easy adhesive layer. Next, the heavy peeling type release sheet was peeled off to expose the adhesive layer, and a laminator (manufactured by FUJIPLA Inc., product name "LPD3214") was used to laminate the adhesive layer on each glass plate with a step difference so that the adhesive layer covers the entire frame-shaped printing surface. Then, the pressure heat treatment was performed at 50°C and 0.5MPa for 30 minutes, and placed at normal pressure, 23°C, and 50%RH for 24 hours.

In addition, for the adhesive sheets of Example 15 and Example 6, the adhesive layer was irradiated with active energy rays (ultraviolet rays) through the PET film to cure the adhesive layer. The irradiation conditions of the active energy rays were the same as those of Test Example 1.

Next, the step followability was evaluated after being stored at 85°C and 85%RH for 500 hours (durability test). The step followability was determined by whether the printed step was completely embedded in the adhesive layer. If floating or peeling was observed at the interface between the printed step and the adhesive layer, it was determined that the printed step could not be followed. Here, the step followability was evaluated in the form of the step followability (%) shown in the following formula. The results are shown in Table 2.

Step following rate (%) = {(height of the step that remains embedded without floating, peeling, etc. after the durability test (μm))/(thickness of the adhesive layer)}×100

[Table 1]

As can be seen from Table 2, the adhesive sheets produced in Examples were excellent in antistatic properties and step followability.

Industrial Applicability

The adhesive sheet of the present invention can be suitably used for laminating a hard protective plate having a step difference and a desired display component member, for example, when manufacturing a display.

Claims (15)

1. An adhesive sheet having an adhesive layer for bonding two display constituent members to each other, the adhesive sheet being characterized by: The thickness of the adhesive layer is 1 μm or more and less than 30 μm, The adhesive constituting the adhesive layer contains an antistatic agent, The gel fraction of the adhesive is 40% or more and 95% or less, Peel off the protective film from the base material in the laminate composed of the ITO-PET film, the adhesive layer, the base material and the protective film at a peeling speed of 2.0 m/min, and after 2 seconds of peeling off, , the peeling electrostatic voltage obtained by measuring the electrostatic potential at a position 2.0cm away from the exposed surface of the ITO-PET film was 0.15kV or less, wherein the ITO-PET film was placed on a 125 μm thick polyterephthalate A tin-doped indium oxide layer is formed on one side of the ethylene glycol ester film, the adhesive layer is laminated on the tin-doped indium oxide layer of the ITO-PET film, the base material is laminated on the adhesive layer, and An acrylic hard coat layer with a thickness of 1.5 μm is formed on one side of a polyethylene terephthalate film with a thickness of 125 μm. The protective film is laminated on the hard coat layer of the base material and has a thickness of An acrylic adhesive layer having a thickness of 15 μm and containing 0.98% by mass of potassium hexafluorophosphate was formed on one side of the 38 μm polyethylene terephthalate film. 2. The adhesive sheet according to claim 1, wherein the adhesive layer has a step tracking rate of 10% or more. 3. The adhesive sheet according to claim 1, wherein the adhesive force of the adhesive sheet to soda-lime glass is 1 N/25mm or more. 4. The adhesive sheet according to claim 1, wherein the adhesive is an inactive energy ray-curable adhesive. 5. The adhesive sheet according to claim 1, characterized in that: The adhesive contains a cross-linked product of (meth)acrylate polymer, The (meth)acrylate polymer contains a structural unit derived from a hard monomer having a homopolymer with a glass transition temperature (Tg) of 70° C. or higher, and a structural unit derived from a nitrogen atom-containing monomer. 6. The adhesive sheet according to claim 1, characterized in that: The adhesive contains a cross-linked product of (meth)acrylate polymer, The (meth)acrylate polymer contains 1 mass % or more and 30 mass % or less of a structural unit derived from a reactive functional group-containing monomer. 7. The adhesive sheet according to claim 1, characterized in that: The adhesive is cross-linked from an adhesive composition containing a (meth)acrylate polymer and a cross-linking agent, The content of the cross-linking agent in the adhesive composition is 0.1 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the (meth)acrylate polymer. 8. The adhesive sheet according to claim 1, wherein the content of the antistatic agent in the adhesive is 0.1% by mass or more and 10% by mass or less. 9. The adhesive sheet according to claim 1, wherein the antistatic agent is an ionic compound. 10. The adhesive sheet according to claim 9, wherein the ionic compound is a nitrogen-containing onium salt or an alkali metal salt. 11. The adhesive sheet according to claim 10, wherein the anion constituting the nitrogen-containing onium salt or the alkali metal salt is a sulfonyl imide anion or a halogenated phosphoric acid anion. 12. The adhesive sheet according to claim 1, characterized in that: The adhesive sheet has two peeling sheets, The adhesive layer is sandwiched between the two release sheets so as to be in contact with the release surfaces of the two release sheets. 13. A display including one display component, another display component, and an adhesive layer bonding the one display component and the other display component, said The characteristics of the display are that, The adhesive layer is formed from the adhesive layer of the adhesive sheet according to any one of claims 1 to 12. 14. The display according to claim 13, wherein at least one of the one display component member and the other display component member is at least on the side bonded by the adhesive layer. The mask is different. 15. The display according to claim 13, wherein both the one display component and the other display component are hard boards.