JP2023150617A - Adhesive sheet and display body - Google Patents

Abstract

To provide an adhesive sheet and a display body, which are excellent in anti-static property and can exhibit excellent step followability even if a thickness of the adhesive layer is thin.SOLUTION: An adhesive sheet 1 having an adhesive layer 11 for adhering two display body constituent members, wherein a thickness of the adhesive layer is 1 μm or more and less than 30 μm; the adhesive constituting the adhesive layer contains an antistatic; and a gel fraction of the adhesive is 40% or more and 95% or less, wherein when a protective film is peeled from a base material in a laminate made of a protective film made of an ITO-PET film, an adhesive layer laminated on the ITO layer of the ITO-PET film, a base material consisting of a PET film/hard coat layer laminated on the adhesive layer, and an acrylic adhesive layer (containing 0.98 mass% of potassium hexafluorophosphate)/PET film laminated on the hard coat layer of the base material, a peeling voltage is 0.15 kV or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pressure-sensitive adhesive sheet for laminating two display body constituent members, and a display body obtained using the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet.

In recent years, various mobile electronic devices such as mobile phones, smartphones, and tablet terminals are equipped with displays that use display modules that include liquid crystal elements, light emitting diodes (LED elements), organic electroluminescence (organic EL) elements, etc. We are prepared.

In such a display, a protective panel is usually provided on the front side of the display module. A gap is provided between the protection panel and the display module so that even when the protection panel is deformed by an external force, the deformed protection panel does not hit the display module.

However, when the above-mentioned voids, i.e., air layers, exist, there is a large reflection loss of light due to the difference in refractive index between the protective panel and the air layer, and the difference in refractive index between the air layer and the display module. There is a problem that image quality deteriorates.

Therefore, it has been proposed to improve the image quality of the display by filling the gap between the protective panel and the display module with an adhesive layer. However, a frame-shaped printed layer may exist as a step on the display module side of the protective panel. If the adhesive layer does not follow the difference in level, the adhesive layer will float near the difference in level, resulting in a reflection loss of light. Therefore, the above-mentioned adhesive layer is required to have level difference followability.

By the way, in the above-mentioned protection panel, static electricity may be generated during the manufacturing process. If a protective panel is bonded to a display module, particularly a liquid crystal cell, in a state where static electricity is generated in this way, there is a risk that the alignment of liquid crystal molecules will be disturbed.

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

Japanese Patent Application Publication No. 2007-316377 Japanese Patent Application Publication No. 2009-155585

However, when an antistatic agent as described above is added to an adhesive composition, the durability of the resulting adhesive tends to be lower than usual. Therefore, as mentioned above, when an adhesive layer containing an antistatic agent is laminated to a protective panel where the printed layer exists as a step, the adhesive layer may lift or peel near the step under high temperature and high humidity conditions. This may occur, and sufficient step followability cannot be obtained.

Incidentally, in recent years, display panels have become significantly thinner, and along with this, there has been a demand for thinner adhesive layers. When the adhesive layer becomes thin, it becomes difficult to sufficiently obtain the above-mentioned level difference followability and antistatic properties.

The present invention has been made in view of the above circumstances, and provides an adhesive sheet and a display that can exhibit excellent antistatic properties and good step followability even if the adhesive layer is thin. The purpose is to provide the body.

In order to achieve the above object, the present invention firstly provides an adhesive sheet having an adhesive layer for bonding two display body constituent members to each other, wherein the adhesive layer has a thickness of 1 μm or more. , less than 30 μm, the adhesive constituting the adhesive layer contains an antistatic agent, the adhesive has a gel fraction of 40% or more and 95% or less, and has a thickness of 125 μm. An ITO-PET film in which a tin-doped indium oxide layer is formed on one side of a terephthalate film, the adhesive layer laminated on the tin-doped indium oxide layer of the ITO-PET film, and the thickness of the adhesive layer laminated on the adhesive layer. A base material with a 1.5 μm thick acrylic hard coat layer formed on one side of a 125 μm polyethylene terephthalate film, and a 38 μm thick polyethylene terephthalate film laminated on the hard coat layer of the base material on one side. The protective film is peeled at a rate of 2.0 m/min from the base material in a laminate comprising a protective film on which a 15 μm thick acrylic adhesive layer containing 0.98% by mass of potassium hexafluorophosphate is formed. The ITO-PET film is peeled off at a high speed, and after 2 seconds of peeling, the electrostatic potential at a position 2.0 cm from the exposed surface of the ITO-PET film is measured, and the peel voltage obtained is 0.15 kV or less. A pressure-sensitive adhesive sheet is provided (invention 1).

By satisfying the above requirements, the adhesive sheet according to the invention (invention 1) exhibits excellent antistatic properties and good step followability even if the adhesive layer is thin. Specifically, a laminate formed by bonding a glass plate with steps and a polyethylene terephthalate film using the adhesive layer is subjected to high temperature and high humidity conditions (e.g., 85° C., 85% RH, 500 hours). Even in this case, the occurrence of lifting, peeling, etc. is suppressed.

In the above invention (invention 1), it is preferable that the level difference following rate of the adhesive layer is 10% or more (invention 2).

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

In the above inventions (Inventions 1 to 3), the adhesive is preferably an active energy ray non-curable adhesive (Invention 4).

In the above inventions (Inventions 1 to 4), the adhesive contains a crosslinked product of a (meth)acrylic ester polymer, and the (meth)acrylic ester polymer has a glass transition state as a homopolymer. It is preferable to include a structural unit derived from a hard monomer having a temperature (Tg) of 70° C. or higher and a structural unit derived from a nitrogen atom-containing monomer (Invention 5).

In the above inventions (Inventions 1 to 5), the adhesive contains a crosslinked product of a (meth)acrylic ester polymer, and the (meth)acrylic ester polymer is a reactive functional group-containing monomer. It is preferable that the structural unit derived from the above-mentioned composition is contained in an amount of 1% by mass or more and 30% by mass or less (Invention 6).

In the above inventions (Inventions 1 to 6), the adhesive is formed by crosslinking an adhesive composition containing a (meth)acrylic acid ester polymer and a crosslinking agent, and The content of the crosslinking agent is preferably 0.1 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the (meth)acrylic acid ester polymer (Invention 7).

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

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

In the invention (invention 9), the ionic compound is preferably a nitrogen-containing onium salt or an alkali metal salt (invention 10).

In the above invention (Invention 10), the anion constituting the nitrogen-containing onium salt or the alkali metal salt is preferably a sulfonylimide anion or a halogenated phosphate anion (Invention 11).

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

Second, the present invention includes one display component, another display component, and an adhesive layer for bonding the one display component and the other display component to each other. Provided is a display body, characterized in that the adhesive layer is formed from the adhesive layer of the adhesive sheet (Inventions 1 to 12) (Invention 13).

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

In the above inventions (Inventions 13 and 14), both the one display member and the other display member may be a hard plate (Invention 15).

The pressure-sensitive adhesive sheet and display body according to the present invention can exhibit excellent antistatic properties and good step followability even if the pressure-sensitive adhesive layer is thin.

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

Embodiments of the present invention will be described below.
[Adhesive sheet]
The adhesive sheet according to 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 constituent members of the display body will be described later.

The thickness of the adhesive layer in this embodiment (value measured according to JIS K7130) is preferably 1 μm or more and less than 30 μm. Moreover, the adhesive constituting the adhesive layer in this embodiment contains an antistatic agent, and preferably has a gel fraction of 40% or more and 95% or less. Note that the method for measuring the gel fraction is as shown in the test example described below.

Furthermore, it is preferable that the adhesive sheet (adhesive layer) according to the present embodiment has a peel voltage of 0.15 kV or less, which is measured as follows. That is, in this embodiment, an ITO-PET film in which a tin-doped indium oxide (ITO) layer is formed on one side of a polyethylene terephthalate (PET) film with a thickness of 125 μm is laminated on the tin-doped indium oxide layer of the ITO-PET film. A base material comprising an adhesive layer and a 1.5 μm thick acrylic hard coat layer formed on one side of a 125 μm thick polyethylene terephthalate (PET) film laminated on the adhesive layer (the PET film side is laminated with the above adhesive layer). a 15 μm thick acrylic adhesive containing 0.98% by mass of potassium hexafluorophosphate on one side of a 38 μm thick polyethylene terephthalate film laminated on the hard coat layer of the substrate. A laminate consisting of a protective film formed with layers (the adhesive layer side is in contact with the hard coat layer) is prepared. Then, the protective film is peeled off from the base material in the laminate at a peeling speed of 2.0 m/min, and after 2 seconds of peeling, the electrostatic potential at a position 2.0 cm from the exposed surface of the ITO-PET film is is measured and taken as the above-mentioned peeling voltage. Note that the details of the method for measuring the peeling electrostatic voltage are as shown in the test examples described below.

By satisfying the above requirements, the adhesive sheet according to the present embodiment exhibits excellent antistatic properties and good step followability even if the adhesive layer is thin. Specifically, a laminate formed by bonding a glass plate with steps and a polyethylene terephthalate film using the adhesive layer is subjected to high temperature and high humidity conditions (e.g., 85° C., 85% RH, 500 hours). Even in this case, the occurrence of lifting, peeling, etc. is suppressed, and the level difference followability described below can be achieved.

The gel fraction of the adhesive in this embodiment is preferably 30% or more, more preferably 35% or more, particularly 38% or more, from the viewpoint of step followability at the initial stage and under high temperature and high humidity conditions. It is preferably 40% or more, and more preferably 40% or more. In addition, the gel fraction of the adhesive in this embodiment is preferably 95% or less, from the viewpoint of step followability at the initial stage and under high temperature and high humidity conditions, and suppressing an increase in resistance after a durability test. % or less, particularly preferably 80% or less, further preferably 65% or less, particularly preferably 60% or less, and most preferably 55% or less. In addition, if the adhesive is an active energy ray-curable adhesive that is cured by irradiation with active energy rays after being applied to the adherend, if the gel fraction value after curing with active energy rays satisfies the above value. good. The method for measuring the gel fraction is as shown in the test example described below.

From the viewpoint of thinning, the thickness of the adhesive layer in this embodiment is preferably less than 30 μm, more preferably 28 μm or less, and particularly preferably 26 μm or less. Further, the thickness of the pressure-sensitive adhesive layer is preferably 1 μm or more, more preferably 3 μm or more, and particularly preferably 5 μm or more from the viewpoint of antistatic properties and step followability.

From the viewpoint of antistatic properties, the peeling voltage is preferably 0.15 kV or less, more preferably 0.13 kV or less, particularly preferably 0.11 kV or less, and even more preferably 0.1 kV. It is preferably less than or equal to 0.1, especially less than 0.1. The lower limit of the peeling voltage is not particularly limited, and may be 0 kV.

In the above laminate, when the protective film is peeled off in the same manner as above from a laminate in which a 1.1 mm thick soda lime glass plate is laminated instead of the ITO-PET film, the peeling voltage is less than 0.7 kV. It is preferably at most 0.6 kV, more preferably at most 0.5 kV, even more preferably at most 0.46 kV, especially preferably at most 0.42 kV. The lower limit of the peeling voltage is not particularly limited and may be 0 kV, but it is usually preferably 0.1 kV or more, particularly preferably 0.2 kV or more, and more preferably 0.3 kV or more. It is preferable that

In the above laminate, when the protective film is peeled off in the same manner as above from a laminate in which soda lime glass plates with a thickness of 0.7 mm are laminated instead of the ITO-PET film, the peeling voltage is 0.9 kV or less. It is preferably at most 0.7 kV, more preferably at most 0.6 kV, even more preferably at most 0.55 kV, especially preferably at most 0.5 kV. The lower limit of the peeling voltage is not particularly limited and may be 0 kV, but it is usually preferably 0.1 kV or more, particularly preferably 0.2 kV or more, and more preferably 0.3 kV or more. It is preferable that

The antistatic agent may be any agent as long as it can exhibit the above-mentioned excellent antistatic properties and good step followability, and examples thereof include ionic compounds, nonionic compounds, etc. Among them, ionic compounds is preferred. The ionic compound may be liquid (ionic liquid) or solid (ionic solid) at room temperature. Here, the ionic compound in this specification refers to a compound in which a cation and an anion are bound together mainly by electrostatic attraction. Note that the antistatic agent may be used alone or in combination of two or more.

The ionic compound is preferably a nitrogen-containing onium salt, a sulfur-containing onium salt, a phosphorus-containing onium salt, an alkali metal salt or an alkaline earth metal salt. Onium salts or alkali metal salts are 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 preferable, and a pyridine ring or an imidazole ring is especially preferable. Further, as the cation constituting the alkali metal salt, lithium ion, potassium ion or sodium ion is preferable, and lithium ion or potassium ion is particularly preferable.

On the other hand, the anion constituting the ionic compound is preferably a halogenated phosphate anion or a sulfonylimide anion. Preferred examples of the halogenated phosphate anion include hexafluorophosphate. Preferable examples of the sulfonylimide anion include bis(fluoroalkylsulfonyl)imide and bis(fluorosulfonyl)imide. Bis(fluoroalkylsulfonyl)imide may be bis(perfluoroalkylsulfonyl)imide, and bis(trifluoromethanesulfonyl)imide is particularly preferred.

Specific examples of nitrogen-containing onium salts having a pyridine ring and a halogenated phosphate anion include 1-butyl-4-methylpyridinium hexafluorophosphate, 1-hexyl-3-methylpyridinium hexafluorophosphate, and 1-hexyl-4-methylpyridinium hexafluorophosphate. Methylpyridinium hexafluorophosphate, 1-octylpyridinium hexafluorophosphate, 1-octyl-4-methylpyridinium hexafluorophosphate, 1-dodecylpyridinium hexafluorophosphate, 1-tetradecylpyridinium hexafluorophosphate, 1-hexadecylpyridinium hexafluorophosphate phosphate, 1-dodecyl-4-methylpyridinium hexafluorophosphate, 1-tetradecyl-4-methylpyridinium hexafluorophosphate, 1-hexadecyl-4-methylpyridinium hexafluorophosphate, and the like. From the viewpoint of the above-mentioned peeling withstand voltage and step followability, the nitrogen-containing onium salt having a pyridine ring and a halogenated phosphate anion is preferably dialkylpyridinium hexafluorophosphate, particularly 1-hexyl-3-methylpyridinium hexafluorophosphate. Fluorophosphate or 1-octyl-4-methylpyridinium hexafluorophosphate is preferred.

Specific examples of nitrogen-containing onium salts having a pyridine ring and a sulfonylimide anion include 1-decylpyridinium bis(fluorosulfonyl)imide, 1-ethylpyridinium bis(fluorosulfonyl)imide, and 1-butylpyridinium bis(fluorosulfonyl)imide. 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, 4-methyl-1-octylpyridinium bis(fluorosulfonyl)imide, and the like. From the viewpoint of the above-mentioned peeling withstand voltage and step followability, the nitrogen-containing onium salt having a pyridine ring and a sulfonylimide anion is preferably dialkylpyridinium bis(fluorosulfonyl)imide, particularly 4-methyl-1-octyl. Pyridinium bis(fluorosulfonyl)imide is preferred. In particular, the above-mentioned antistatic agent is preferable because it improves step followability while making it easier to satisfy the above-mentioned peeling withstand voltage.

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

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, lithium bis(trifluoromethanesulfonyl)imide, and the like. Among these, potassium bis(fluorosulfonyl)imide or lithium bis(trifluoromethanesulfonyl)imide is preferable from the viewpoint of the above-mentioned peeling withstand voltage and step followability.

The content of the antistatic agent in the adhesive in this embodiment is preferably 0.1 to 10% by mass, more preferably 0.5 to 8% by mass, particularly 1 to 7% by mass. The amount is preferably 2 to 6% by weight, particularly preferably 2 to 5% by weight, and most preferably 2.9 to 4% by weight. By setting the lower limit of the content of the antistatic agent to the above value, it becomes easier to satisfy the above-mentioned value of peel strength voltage, and the antistatic property becomes more excellent. Further, by setting the upper limit of the content of the antistatic agent to the above value, the step followability becomes better.

The adhesive in this embodiment may be any one of an acrylic adhesive, a polyester adhesive, a polyurethane adhesive, a rubber adhesive, a silicone adhesive, and the like. Further, the adhesive may be of an emulsion type, a solvent type, or a solvent-free type, and may be a crosslinked type or a non-crosslinked type. Among them, acrylic pressure-sensitive adhesives are preferred because of their excellent adhesive properties, optical properties, and the like.

The acrylic adhesive may be active energy ray-curable, active energy ray non-curable, crosslinkable, or non-crosslinkable. It may be one or a combination of these. Among these, from the viewpoint of suppressing changes in resistance value, active energy ray non-curable acrylic pressure-sensitive adhesives are preferred. As the active energy ray non-curable acrylic pressure-sensitive adhesive, a crosslinked type is particularly preferable, and a thermally crosslinked type is more preferable.

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

(1) Each component (1-1) (meth)acrylic acid ester polymer (A)
The (meth)acrylic acid ester polymer (A) preferably contains a structural unit derived from an alkyl (meth)acrylic ester. Thereby, good adhesiveness can be developed. Note that the hard monomer described below is excluded from the (meth)acrylic acid alkyl ester.

As the (meth)acrylic acid alkyl ester, from the viewpoint of adhesiveness, (meth)acrylic acid alkyl esters in which the alkyl group has 1 to 20 carbon atoms are preferable. Examples of (meth)acrylic acid alkyl esters in which the alkyl group has 1 to 20 carbon atoms include 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 , myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, and the like. These may be used alone or in combination of two or more. Among the above, from the viewpoint of further improving adhesiveness, (meth)acrylic esters in which the alkyl group has 1 to 14 carbon atoms are preferred, and (meth)acrylic esters in which the alkyl group has 4 to 10 carbon atoms are more preferred. Preferably, (meth)acrylic acid esters in which the alkyl group has 5 to 8 carbon atoms are particularly preferable. Specifically, for example, methyl acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or isooctyl (meth)acrylate is preferable, and 2-ethylhexyl acrylate is preferable. is particularly preferred.

From the viewpoint of imparting tackiness, the (meth)acrylic acid ester polymer (A) preferably contains 30 to 95% by mass, and preferably 45 to 85% by mass, of structural units derived from alkyl (meth)acrylic esters. The content is more preferably 55 to 80% by mass, and even more preferably 62 to 75% by mass from the viewpoint of step followability.

It is preferable that the (meth)acrylic acid ester polymer (A) has a structural unit derived from a monomer containing a reactive functional group. Thereby, the reactive functional group derived from the reactive functional group-containing monomer reacts with the crosslinking agent (B), a crosslinked structure (three-dimensional network structure) is formed, and an adhesive having a desired cohesive force is obtained.

Reactive group-containing monomers include monomers that have a hydroxyl group in the molecule (hydroxyl group-containing monomer), monomers that have a carboxyl group in the molecule (carboxy group-containing monomer), and monomers that have an amino group in the molecule (amino group-containing monomer). etc. are preferably mentioned. Among these, hydroxyl group-containing monomers or carboxy group-containing monomers that have excellent reactivity with the crosslinking agent (B) are preferred, and hydroxyl group-containing monomers are more preferred from the viewpoint of suppressing changes in resistance value.

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

Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferred from the viewpoint 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)acrylic acid ester polymer (A) is preferably 1 to 30% by mass, and 3 to 25% by mass from the viewpoint of cohesive force. It is more preferable that the amount is 5 to 20% by mass, and even more preferably 10 to 18% by mass, from the viewpoint of suppressing resistance change and improving the dielectric constant.

The (meth)acrylic acid ester polymer (A) preferably contains a structural unit derived from a hard monomer having a glass transition temperature (Tg) of 70° C. or higher as a homopolymer. Note that the above-mentioned reactive functional group-containing monomers are excluded from the hard monomers. When the (meth)acrylic acid ester polymer (A) contains the structural unit derived from the above-mentioned hard monomer, the resulting adhesive has improved cohesive force and excellent durability. In particular, when containing a structural unit derived from a (meth)acrylic acid ester in which the alkyl group has 5 to 8 carbon atoms, the cohesive force tends to be low. is preferred. The glass transition temperature (Tg) of the hard monomer as a homopolymer is preferably 75 to 200°C, particularly preferably 80 to 180°C, and even more preferably 90 to 150°C.

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

Among the above-mentioned hard monomers, methyl methacrylate, isobornyl acrylate, or acryloylmorpholine are more preferable from the viewpoint of maximizing the performance of the hard monomer while preventing adverse effects on other properties such as stickiness and transparency. Particularly preferred is isobornyl acrylate, which is a monomer having an alicyclic structure (monomer containing an alicyclic structure).

From the viewpoint of cohesive force and durability, the (meth)acrylic acid ester polymer (A) preferably contains 0.5 to 30% by mass, and preferably 1 to 27% by mass, of the structural unit derived from the hard monomer. More preferably, from the viewpoint of better step followability, the content is particularly preferably 3 to 25% by mass, even more preferably 5 to 22% by mass, and especially preferably 10 to 20% by mass. .

It is also preferable that the (meth)acrylic acid ester polymer (A) contains a structural unit derived from a monomer having a nitrogen atom in the molecule (nitrogen atom-containing monomer). In particular, when an alicyclic structure-containing monomer, particularly isobornyl acrylate, is used as the hard monomer, it is preferable to contain a structural unit derived from a nitrogen atom-containing monomer. The presence of a structural unit derived from a nitrogen atom-containing monomer imparts a predetermined polarity to the pressure-sensitive adhesive, thereby making it possible to improve step followability.

As the nitrogen atom-containing monomer, a monomer having a nitrogen-containing heterocycle is preferable from the viewpoint of imparting appropriate rigidity to the (meth)acrylic acid ester polymer (A). In addition, from the viewpoint of increasing the degree of freedom of the portion derived from the nitrogen atom-containing monomer in the higher-order structure of the adhesive, the nitrogen atom-containing monomer is used to form the (meth)acrylic acid ester polymer (A). It is preferred not to contain any reactive unsaturated double bond groups other than the one polymerizable group used in the polymerization of.

Examples of monomers having a nitrogen-containing heterocycle include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloyl Pyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl (meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N-(meth)acryloylmorpholine, which exhibits superior adhesive strength, is preferred, and N-acryloylmorpholine is particularly preferred. These may be used alone or in combination of two or more.

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

The (meth)acrylic acid ester polymer (A) may contain structural units derived from other monomers, if desired. As other monomers, monomers that do not contain reactive functional groups are preferred in order not to interfere with the action of the hydroxyl group-containing monomer. Examples of such other monomers include alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

The (meth)acrylic acid ester polymer (A) may be solution polymerized, solvent-free polymerized, or emulsion polymerized. Among these, a solution polymer obtained by a solution polymerization method is preferable. Since it is a solution polymer, it is easy to obtain a high molecular weight polymer, and an adhesive with excellent step followability can be obtained.

The polymerization mode of the (meth)acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably from 200,000 to 2,000,000, more preferably from 300,000 to 1,500,000, particularly preferably from 350,000 to 1,200,000. Preferably, from the viewpoint of better step followability, it is more preferably 400,000 to 1,000,000, particularly preferably 450,000 to 800,000, and most preferably 480,000 to 680,000. Note that the weight average molecular weight in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

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

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

(1-2) Crosslinking agent (B)
The crosslinking agent (B) crosslinks the (meth)acrylic acid ester polymer (A) by heating the adhesive composition P, making it possible to form a three-dimensional network crosslinked structure well. As a result, an adhesive having a predetermined cohesive force can be obtained, and the step followability can be improved.

The crosslinking agent (B) may be one that reacts with the reactive functional group (hydroxyl group or carboxy group) of the (meth)acrylic acid ester polymer (A), such as an isocyanate crosslinking agent, an epoxy-based crosslinking agent, etc. 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-based crosslinking agents, and the like. Here, when the (meth)acrylic acid ester polymer (A) contains a structural unit derived from a hydroxyl group-containing monomer, an isocyanate-based crosslinking agent having excellent reactivity with hydroxyl groups is used as the crosslinking agent (B). It is preferable to use In addition, when the (meth)acrylic acid ester polymer (A) contains a structural unit derived from a carboxyl group-containing monomer, the crosslinking agent (B) is an epoxy crosslinking agent that has excellent reactivity with carboxyl groups. Alternatively, it is preferable to use a metal chelate crosslinking agent. Note that the crosslinking agent (B) can be used alone or in combination of two or more.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, and alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate. and their biuret forms, isocyanurate forms, and adduct forms which are reactants with low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate or trimethylolpropane-modified xylylene diisocyanate, are preferred from the viewpoint of reactivity with hydroxyl groups.

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

Examples of metal chelate crosslinking agents include chelate compounds in which the metal atom is aluminum, zirconium, titanium, zinc, iron, tin, etc., but from the viewpoint of reactivity with the (meth)acrylic acid ester polymer (A) Aluminum chelate compounds are preferred.

Examples of aluminum chelate compounds include diisopropoxyaluminum monooleylacetoacetate, monoisopropoxyaluminum bisoleylacetoacetate, monoisopropoxyaluminum monooleate monoethylacetoacetate, diisopropoxyaluminum monolauryl acetoacetate, diisopropoxy Aluminum monostearylacetoacetate, diisopropoxyaluminum monoisostearylacetoacetate, monoisopropoxyaluminum mono-N-lauroyl-β-alanate monolauryl acetoacetate, aluminum trisacetylacetonate, monoacetylacetonate aluminum bis(isobutylacetonate) acetate) chelate, monoacetylacetonate aluminum bis(2-ethylhexylacetoacetate) chelate, monoacetylacetonate aluminum bis(dodecyl acetoacetate) chelate, monoacetylacetonate aluminum bis(oleylacetoacetate) chelate, and the like. Among the above, aluminum trisacetylacetonate is particularly preferred from the viewpoint of reactivity and the fact that the resulting adhesive tends to have the desired adhesive strength.

The content of the crosslinking agent (B) in the adhesive composition P is 0.01 to 10 parts by mass from the viewpoint of cohesive force with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A). It is preferably 0.04 to 5 parts by mass, more preferably 0.08 to 1 part by mass, and from the viewpoint of better step followability, 0.1 to 0.5 parts by mass. Parts by weight are more preferable, and 0.12 to 0.2 parts by weight are most preferable.

(1-3) Antistatic agent (C)
The type of antistatic agent (C) and the content (% by 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, based on 100 parts by mass of the (meth)acrylic acid ester polymer (A), and 0. The amount is more preferably 5 to 8 parts by weight, particularly preferably 1 to 6 parts by weight, and even more preferably 2 to 4 parts by weight. When the content of the antistatic agent is within the above range, it becomes easier to satisfy the above-mentioned peel withstand voltage value, resulting in better antistatic properties and better step followability.

(1-4) Silane coupling agent (D)
It is preferable that the adhesive composition P further contains a silane coupling agent (D). As a result, when there is a glass member on the adherend, the resulting adhesive has improved adhesion to the glass member. Further, even if the adherend is a plastic plate, the resulting adhesive has improved adhesion to the plastic plate. Thereby, the resulting adhesive has better step followability. Furthermore, it has excellent adhesion to metal electrodes such as metal wiring, and tends to contribute to suppressing the rate of change in resistance value.

The silane coupling agent (D) is an organosilicon compound having at least one alkoxysilyl group in the molecule, has good compatibility with the (meth)acrylic acid ester polymer (A), and has good light transmittance. It is preferable to have one.

Examples of the silane coupling agent (D) include silicon compounds containing polymerizable unsaturated groups such as vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, Silicon compounds having an epoxy structure such as 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, Mercapto group-containing silicon compounds such as 3-mercaptopropyldimethoxymethylsilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3 - An amino group-containing silicon compound such as aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or at least one of these, and methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxy Examples include condensates with alkyl group-containing silicon compounds such as silane and ethyltrimethoxysilane. These may 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 based on 100 parts by mass of the (meth)acrylic acid ester polymer (A), The amount is more preferably 0.1 to 0.7 parts by weight, particularly preferably 0.2 to 0.5 parts by weight.

(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 better step followability before curing, and the pressure sensitive adhesive after curing has better step followability.

The active energy ray-curable component (E) is not particularly limited as long as it is a component that can be cured by irradiation with active energy rays and provides the above effects, and may be any monomer, oligomer, or polymer; It may be a mixture of. Among these, polyfunctional acrylate monomers are preferred because they have better step followability.

Examples of polyfunctional acrylate monomers include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate. , neopentyl glycol adipate di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone modified dicyclopentenyl di(meth)acrylate, ethylene oxide modified phosphoric acid di(meth)acrylate, 2 such as meth)acrylate, di(acryloxethyl)isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, etc. Functional type: 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 ) acrylate, trifunctional type such as tris(acryloxyethyl)isocyanurate, ε-caprolactone modified tris-(2-(meth)acryloxyethyl)isocyanurate; diglycerin tetra(meth)acrylate, pentaerythritol tetra(meth) Tetrafunctional types such as acrylate; Pentafunctional types such as propionic acid-modified dipentaerythritol penta(meth)acrylate; Hexafunctional types such as dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate. Can be mentioned. Among the above, from the viewpoint of step followability of the resulting adhesive, di(acryloxyethyl) isocyanurate, tris(acryloxyethyl) isocyanurate, ε-caprolactone modified tris-(2-(meth)acryloxyethyl) Polyfunctional acrylate monomers containing an isocyanurate structure in the molecule such as isocyanurate are preferred, and polyfunctional acrylate monomers having three or more functionalities and containing an isocyanurate structure in the molecule are more preferred, and ε-caprolactone-modified tris -(2-(meth)acryloxyethyl)isocyanurate is particularly preferred. These may be used alone or in combination of two or more. Moreover, from the viewpoint of compatibility with the (meth)acrylic acid ester polymer (A), the polyfunctional acrylate monomer preferably has a molecular weight of less than 1000.

The content of the active energy ray-curable component (E) in the adhesive composition P is determined from the viewpoint of improving the cohesive force of the resulting adhesive and providing excellent step followability. The amount is preferably from 1 to 20 parts by weight, particularly preferably from 3 to 12 parts by weight, and even more preferably from 4 to 8 parts by weight, based on 100 parts by weight of the combined (A).

(1-6) Various additives The adhesive composition P may optionally contain various additives commonly used in acrylic adhesives, such as ultraviolet absorbers, tackifiers, antioxidants, light stabilizers, and softeners. It may also contain agents, fillers, refractive index modifiers, and the like.

Examples of ultraviolet absorbers include benzophenone-based, benzotriazole-based, benzoate-based, benzoxazinone-based, triazine-based, phenylsalicylate-based, cyanoacrylate-based, and nickel complex-based compounds. Among these, benzophenone-based It is preferable to use at least one of a compound, a benzotriazole compound, and a triazine compound.

Examples of the above benzophenone compounds include 2,2-dihydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid water. Among these, it is preferable to use 2,2-dihydroxy-4-methoxybenzophenone. 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, and preferably 0.5 to 20 parts by mass, based on 100 parts by mass of the (meth)acrylic acid ester polymer (A). It is more preferably 15 parts by weight, particularly preferably 1 to 10 parts by weight, and even more preferably 2 to 5 parts by weight.

When the adhesive composition P contains the active energy ray-curable component (E) and uses ultraviolet rays as the active energy ray, it is preferable to contain a photopolymerization initiator. By containing a photopolymerization initiator, the active energy ray-curable component (E) can be efficiently cured, and the polymerization curing time and the amount of ultraviolet ray 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-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]- 2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4'-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-dimethylaminobenzoic acid ester, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 2,4,6-trimethylbenzoyl- Examples include diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. 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 4 to 18 parts by mass, based on 100 parts by mass of the active energy ray-curable component (E). The amount is preferably 6 to 15 parts by mass, and more preferably 6 to 15 parts by mass.

(2) Manufacture of adhesive composition Adhesive composition P is produced by manufacturing a (meth)acrylic ester polymer (A), and combining the obtained (meth)acrylic ester polymer (A) with a crosslinking agent ( It can be produced by mixing B) and the antistatic agent (C), and optionally adding a silane coupling agent (D), an active energy ray-curable component (E), additives, etc.

The (meth)acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer using a conventional radical polymerization method. The (meth)acrylic acid ester polymer (A) is preferably polymerized by a solution polymerization method using a polymerization initiator if desired. However, the present invention is not limited to this, and polymerization may be performed without a solvent. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.

Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more types may be used in combination. Examples of azo compounds 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 2,2'-azobis(2-methylpropionate) , 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), 2,2'-azobis[2-(2-imidazolin-2-yl) Propane], etc.

Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl)peroxy Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxy bivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

In the above polymerization step, the weight average molecular weight of the resulting polymer can be adjusted by incorporating a chain transfer agent such as 2-mercaptoethanol.

Once the (meth)acrylic acid ester polymer (A) is obtained, a crosslinking agent (B), an antistatic agent (C), and optionally silane coupling are added to the solution of the (meth)acrylic acid ester polymer (A). The adhesive composition P (coating solution) diluted with the solvent is obtained by adding the agent (D), the active energy ray-curable component (E), additives, diluting solvent, etc., and thoroughly mixing them. In addition, if any of the above components is used in solid form, or if precipitation occurs when mixed with other components in an undiluted state, that component alone must be diluted with a diluting solvent in advance. It may be mixed with other components after being dissolved or diluted.

Examples of the diluent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride, and ethylene chloride, methanol, ethanol, propanol, butanol, Alcohols such as 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve are used.

The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within a coating range, and can be appropriately selected depending on the situation. For example, the adhesive composition P is diluted to a concentration of 10 to 60% by mass. In addition, when obtaining a coating solution, addition of a dilution solvent etc. is not a necessary condition, and if adhesive composition P has a viscosity etc. which can be coated, it is not necessary to add a dilution solvent. In this case, the adhesive composition P becomes a coating solution using the polymerization solvent of the (meth)acrylic acid ester polymer (A) as a diluting solvent.

(3) Production of adhesive The adhesive composition P described above is applied to a desired object and then crosslinked to obtain an adhesive (adhesive layer).

Crosslinking of the adhesive composition P can be performed by heat treatment. This heat treatment can also serve as a drying treatment after applying the adhesive composition P. The heating temperature of the heat treatment is preferably 50 to 150°C, particularly preferably 70 to 120°C. Further, the heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes.

After the heat treatment, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, 23° C., 50% RH), if necessary. If this curing period is necessary, the adhesive is formed after the curing period has elapsed; if this curing period is not necessary, the adhesive is formed after the heat treatment is completed.

By the above heat treatment (and curing), the (meth)acrylic acid ester polymer (A) is sufficiently crosslinked via the crosslinking agent (B). In the adhesive layer obtained in this way, good step followability is obtained.

In addition, when the adhesive composition P contains an active energy ray-curable component (E), after applying the adhesive composition P to a desired object and performing a heat treatment as described above, the active energy ray curable component (E) is applied. Although the adhesive composition P may be cured by irradiation to form an adhesive (adhesive layer), it is preferable to apply it to an adherend in a state before irradiation with active energy rays and then irradiate it with active energy rays. is preferred. Thereby, the step followability at the initial stage becomes more excellent.

(4) Physical properties of adhesive (adhesive layer) (4-1) Adhesive force The adhesive force of the adhesive sheet according to this embodiment to soda lime glass is preferably 1 to 100 N/25 mm as a lower limit, and 5 -60N/25mm is more preferable, particularly preferably 10-40N/25mm or more, furthermore preferably 15-35N/25mm or more, and especially preferably 20-30N/25mm, Most preferably, it is 25 to 27 N/25 mm. When the lower limit of the adhesive force of the adhesive sheet is above, the step followability becomes more excellent. Further, when the upper limit of the adhesive force is within the above range, reworkability is excellent while maintaining good step followability.

In addition, in the case where the adhesive composition P is an adhesive containing an active energy ray-curable component (E), the adhesive force after irradiation with active energy rays only needs to satisfy the above value. The adhesive strength before irradiation with active energy rays is not particularly limited.

Here, the above-mentioned adhesive strength basically refers to the adhesive strength measured by the 180 degree peeling method according to JIS Z0237:2009, and the specific test method is as shown in the test example described below.

(4-2) Haze value The haze value of the adhesive layer of the adhesive sheet according to this embodiment is preferably 1% or less, more preferably 0.6% or less, particularly 0.4% or less. The content is preferably 0.2% or less, and more preferably 0.2% or less. When the haze value of the pressure-sensitive adhesive layer is within the above range, transparency is very high and it is suitable for optical applications (displays). On the other hand, the lower limit of the haze value of the adhesive layer is not particularly restricted. Although the lower limit value may be 0%, it is usually about 0.1% due to measurement accuracy and the like. Here, the haze value in this specification is a 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 according to the present embodiment is preferably 70% or more, preferably 80% or more, particularly 90% or more. % or more, more preferably 99% or more. When the total light transmittance of the adhesive layer is within the above range, 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 in this specification is a value measured according to JIS K7361-1:1997.

(4-4) Surface resistivity When a voltage of 100 V is applied for 10 seconds to the adhesive sheet (adhesive layer/release sheet) according to this embodiment in an environment of 23°C and 50% RH, the adhesive The upper limit of the surface resistivity of the exposed surface of the layer is preferably 1.0×10 ¹³ Ω/sq or less, more preferably 5.0×10 ¹² Ω/sq or less, particularly 1. It is preferably at most 0×10 ¹² Ω/sq, more preferably at most 5.0×10 ¹¹ Ω/sq, and especially preferably at most 2.0×10 ¹¹ Ω/sq. When the upper limit value of the surface resistivity is as described above, excellent antistatic properties are exhibited, and the above-mentioned peeling voltage is easily satisfied. The lower limit of the surface resistivity is not particularly limited, but it is usually preferably 1.0×10 ⁵ Ω/sq or more, particularly preferably 1.0×10 ⁶ Ω/sq or more, and is preferably 1.0×10 ⁷ Ω/sq or more. Note that the surface resistivity of the adhesive layer is measured in accordance with JIS K6911:2006, and specifically as shown in the test example described below.

(4-5) Volume resistivity When a voltage of 100 V is applied for 10 seconds to the adhesive sheet (adhesive layer/release sheet) according to the present embodiment in an environment of 23°C and 50% RH, the adhesive The upper limit of the volume resistivity of the layer is preferably 1.0×10 ¹² Ω/sq or less, more preferably 1.0×10 ¹¹ Ω/sq or less, particularly 5.0×10 It is preferably ¹⁰ Ω/sq or less, more preferably 1.0×10 ¹⁰ Ω/sq or less, especially preferably 5.0×10 ⁹ Ω/sq, and 1.8× Most preferably, it is 10 ⁹ Ω/sq or less. When the upper limit of the volume resistivity is within the above range, excellent antistatic properties are exhibited, and the above-mentioned peeling voltage is easily satisfied. The lower limit of the volume resistivity is not particularly limited, but it is usually preferably 1.0 x 10 ⁵ Ω/sq or more, particularly preferably 1.0 x 10 ⁶ Ω/sq or more, and is preferably 1.0×10 ⁷ Ω/sq or more. Note that the volume resistivity of the adhesive layer is measured in accordance with JIS K6911:2006, and specifically as shown in the test example described below.

(4-6) Resistance value change rate Generally, when a conductive layer and an adhesive layer are laminated in contact with each other and subjected to durability conditions, a phenomenon is observed in which the resistance value of the conductive layer increases. However, with the adhesive layer in this embodiment, such an increase in resistance value can be minimized, although the reason is not clear.

Specifically, the adhesive layer of this embodiment is pasted on a glass plate, and a conductive layer (for example, made of tin-doped indium oxide (ITO) (transparent conductive film) is laminated. A base material (for example, a polyethylene terephthalate film) for holding the conductive layer is arranged on the surface of the conductive layer opposite to the surface in contact with the adhesive layer. The glass plate/adhesive layer/conductive layer/substrate structure was placed under moist heat conditions of 85°C and 85% RH for 500 hours (durability test), and the resistance value of the conductive layer before and after the durability test was measured. Measure. In this case, the ratio of the resistance value after durability to the resistance value before durability (rate of change in resistance value: (resistance value after durability/resistance value before durability) x 100) is preferably 300% or less, It is more preferably 200% or less, particularly preferably 150% or less, and even more preferably 130% or less. On the other hand, the lower limit of the resistance value change rate is not particularly limited, but is approximately 1%. Note that in the above test, a base material is used as a member for holding the conductive layer, but it is presumed that the results obtained will be the same whether this is a glass plate or a resin plate. The detailed test method for the rate of change in resistance value is as shown in the test example described below.

(4-7) Dielectric constant The dielectric constant at 0.1 MHz of the adhesive in this embodiment is preferably 2.0 to 14.0, more preferably 4.0 to 12.0, particularly It is preferably from 5.0 to 10.0, more preferably from 6.0 to 9.0, and especially preferably from 7.0 to 8.0. When the dielectric constant is within the above range, excellent antistatic properties are exhibited, and the above-mentioned peeling voltage is easily satisfied.

(4-8) Level difference tracking rate The adhesive layer in this embodiment has a level difference tracking rate (%) expressed by the following formula, preferably from 10 to 80%, preferably from 20 to 70%. , particularly preferably 30 to 60%, more preferably 40 to 50%.
Level difference tracking rate (%) = {(Height of level difference that remained filled without lifting, peeling, etc. after specified durability test (μm))/(Thickness of adhesive layer)} x 100
Note that the test method for the level difference tracking rate is as shown in the test example described below.

(5) Specific configuration of adhesive sheet FIG. 1 shows a specific configuration as an example of the adhesive sheet according to the present embodiment.
As shown in FIG. 1, the adhesive sheet 1 according to one embodiment includes two release sheets 12a and 12b, and the two release sheets 12a are in contact with the release surfaces of the two release sheets 12a and 12b. , 12b. Note that the release surface of a release sheet in this specification refers to the surface of the release sheet that has releasability, and includes both a surface that has been subjected to release treatment and a surface that exhibits releasability even without being subjected to release treatment. .

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 according to this embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

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

It is preferable that the release surfaces of the release sheets 12a, 12b (particularly the surfaces in contact with the adhesive layer 11) are subjected to a release treatment. Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

The thickness of the release sheets 12a, 12b is not particularly limited, but is usually about 20 to 150 μm.

In the two release sheets 12a and 12b, one of the release sheets is preferably a heavy release type release sheet with a high peel force, and the other release sheet is preferably a light release type release sheet with a low peel force. In particular, since the thickness of the adhesive layer in this embodiment is thin and the handling property is likely to deteriorate, it is preferable that the two release sheets 12a and 12b each have a predetermined release force. It is preferable that the sheets 12a and 12b have a predetermined difference in peeling force.

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

The peeling force when peeling the heavy release type release sheet from the adhesive layer in this embodiment is preferably 20 to 300 mN/25 mm, more preferably 50 to 200 mN/25 mm, and particularly 90 to 150 mN/25 mm. It is preferably 25 mm, more 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 40 to 150 mN/25 mm. It is preferably 70 mN/25 mm, more preferably 44 to 52 mN/25 mm.

By having the respective peeling forces and peeling force differences within the above ranges, it is possible to suppress the occurrence of so-called tear separation when peeling off a light-release type release sheet, and the adhesive layer can be used as a heavy-release type release sheet. The easy-release type release sheet can be peeled off smoothly without peeling off from the surface. Furthermore, unintended peeling of each release sheet can be suppressed, and furthermore, heavy release type release sheets can be peeled off favorably.

Here, the above-mentioned peeling force basically refers to the peeling force measured by the 180 degree peeling method according to JIS Z0237:2009, and the specific test method is as shown in the test example described below.

(6) Manufacture of adhesive sheet As an example of manufacturing the adhesive sheet 1, a coating liquid of the adhesive composition P is applied to the release surface of one of the release sheets 12a (or 12b), and heat treatment is performed to make the adhesive sheet sticky. After the adhesive composition P is thermally crosslinked to form a coating layer, the release surface of the other release sheet 12b (or 12a) is superimposed on the coating layer. If a curing period is required, a curing period is provided, and if a curing period is not required, the coating layer becomes the adhesive layer 11 as is. Through the above steps, the adhesive sheet 1 is obtained. The conditions for heat treatment and curing 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 used.

[Display body]
A display according to an embodiment of the present invention includes one display component, another display component, and an adhesive layer that bonds the one display component and the other display component to each other. It is equipped with The adhesive layer is formed from the adhesive layer of the adhesive sheet according to the embodiment described above.

At least one of the one display component and the other display component may have a step at least on the surface bonded by the pressure-sensitive adhesive layer. Since the adhesive layer in this embodiment has excellent step followability, it is suppressed from floating or peeling near the step even under high temperature and high humidity conditions.

Both of the first display component and the other display component may be a hard plate. When attaching two hard plates to each other, since the hard plates are hard and do not bend, by pressing the two hard plates in a vertical direction with the adhesive layer attached to one of the plates, Each hard plate and the adhesive layer are brought into close contact with each other, thereby bonding the two hard plates to each other. In the adhesive layer in this embodiment, since the gel fraction of the adhesive is within the above-mentioned range, two hard plates can be bonded well in the above-described bonding method.

A display body according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 2, the display 2 according to the present embodiment includes a first display component 21 (one display component) and a second display component 22 (another display component). ), and an adhesive layer 11 located between them and bonding the first display component 21 and the second display component 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 side bonded by the adhesive layer 11. In the present embodiment shown in FIG. 2, the first display member 21 has a step such as the printed layer 3 on the surface on the adhesive layer 11 side.

The adhesive layer 11 in the display body 2 is the adhesive layer 11 of the adhesive sheet 1 described above.
The adhesive layer 11 of the adhesive sheet 1 described above may be cured by irradiation with active energy rays.

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

The first display component 21 is preferably a protective panel made of a glass plate, a plastic plate, etc., or a laminate including them. In this case, the printed layer 3 is generally formed in the shape of a frame on the adhesive layer 11 side of the first display component 21.

The above-mentioned 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. Examples include glass. 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 above-mentioned plastic plate is not particularly limited, and examples thereof include an acrylic plate, a polycarbonate plate, and the like. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

Note that various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, anti-glare layer, etc.) may be provided on one or both sides of the glass plate or plastic plate, and optical members may be provided on one or both sides of the glass plate or plastic plate. may be stacked. Further, the transparent conductive film and the metal layer may be patterned.

The second display component 22 includes an optical member 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 electroluminescence (organic (EL) module, etc.), an optical member as a part of a display module, or a laminate including a display module.

Examples of the above-mentioned optical members include anti-scattering films, polarizing plates (polarizing films), polarizers, retardation plates (retardation films), viewing angle compensation films, brightness enhancement films, contrast enhancement films, liquid crystal polymer films, and diffusion films. , transflective film, transparent conductive film, etc. A preferred example of the transparent conductive film is an ITO-PET film in which a tin-doped indium oxide (ITO) layer is formed on one side of a polyethylene terephthalate film.

The material constituting the printing layer 3 is not particularly limited, and known materials for printing can be used. The thickness of the printed layer 3, ie, 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. When the thickness of the printed layer 3 is within the above range, the pressure-sensitive adhesive layer 11 can effectively follow the step difference, and the printing layer 3 can sufficiently maintain its concealing property. Note that the printed layer 3 is generally formed in the shape of a frame on the adhesive layer 11 side of the display component.

In order to manufacture the display body 2, for example, one release sheet 12a of the pressure-sensitive adhesive sheet 1 is peeled off, and the exposed pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 is transferred to the printed layer of the first display structure member 21. Paste it on the side where 3 is present. At this time, since the adhesive layer 11 made of an adhesive with a controlled gel fraction has excellent initial step followability, it is possible to suppress the formation of gaps or floating in the vicinity of the steps caused by the printed layer 3.

Next, the other release sheet 12b is peeled off from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 of the adhesive sheet 1 and the second display body constituent member 22 are bonded together to obtain a display body. . Moreover, as another example, the bonding order of the first display body constituent member 21 and the second display body constituent member 22 may be changed.

Here, when the adhesive composition P contains the active energy ray-curable component (E), the laminate of the first display member 21 and the adhesive layer 11 and the second display member 22 are combined. After lamination, the adhesive layer 11 may be cured by irradiating the adhesive layer 11 with active energy rays through the first display component 21 and/or the second display component 22. preferable. Thereby, the level difference followability becomes more excellent.

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

Irradiation of ultraviolet rays can be carried out using a high-pressure mercury lamp, Fusion H lamp, xenon lamp, etc., and the amount of irradiation of ultraviolet rays is preferably about 50 to 1000 mW/cm ² . Further, the amount of light is preferably 50 to 10,000 mJ/cm ² , more preferably 80 to 5,000 mJ/cm ² , and particularly preferably 300 to 2,000 mJ/cm ² . On the other hand, the electron beam irradiation can be performed using an electron beam accelerator or the like, and the amount of electron beam irradiation is preferably about 10 to 1000 krad.

In the display body 2, the adhesive layer 11 has excellent step followability under high temperature and high humidity conditions, so that the display body 2 is Even when placed, the occurrence of floating, peeling, etc. near the step is suppressed.

Since the adhesive layer 11 has excellent antistatic properties, for example, the protective film attached to the surface (exposed surface) of the first display component 21 (protective panel) can be peeled off from the first display component 21. When this happens, the generation of static electricity can be effectively suppressed. This suppresses the occurrence of problems caused by static electricity in the members inside the display body 2. As a specific example, problems such as deterioration or destruction of the electrode made of ITO and deterioration of the responsiveness of the touch panel (delay, non-response, etc.) are suppressed.

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

For example, one or both of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted, and a desired optical member may be laminated instead of the release sheets 12a and/or 12b. Further, the first display member 21 may not have a step. Furthermore, not only the first display component 21 but also the second display component 22 may have a step on the adhesive layer 11 side.

In addition, in this specification, when "X to Y" (X, Y are arbitrary numbers) is written, unless otherwise specified, it means "more than or equal to X and less than or equal to Y", and also means "preferably larger than X" or "preferably is less than Y." In addition, when it is written as "more than or equal to X" (X is any number), unless otherwise specified, it includes the meaning of "preferably larger than X", and when it is written as "less than or equal to Y" (where Y is any number) , unless otherwise specified, also includes the meaning of "preferably smaller than Y".

Hereinafter, the present invention will be explained in more detail with reference to examples, but the scope of the present invention is not limited to these examples.

[Example 1]
1. Preparation of (meth)acrylic acid ester polymer 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 a solution polymerization method. An acid ester polymer (A) was prepared. When the molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method described below, it was found to have a weight average molecular weight (Mw) of 700,000.

2. Preparation of adhesive composition 100 parts by mass of the (meth)acrylic acid ester polymer (A) obtained in the above step 1 (solid content equivalent value; the same applies hereinafter) and an isocyanate-based crosslinking agent (B1; manufactured by Mitsui Chemicals, Inc., Product name "Takenate D-101E") 0.25 parts by mass, 1.0 parts by mass of 4-methyl-1-octylpyridinium bis(fluorosulfonyl)imide (C1) as an antistatic agent (C), and a silane cup. A coating solution of an adhesive composition was obtained by mixing with 0.25 parts by mass of 3-glycidoxypropyltrimethoxysilane as a ring agent (D), stirring thoroughly, and diluting with methyl ethyl ketone.

Here, Table 1 shows each formulation (in terms of solid content) of the adhesive composition when the (meth)acrylic acid ester polymer (A) is 100 parts by mass (in terms of solid content). The details of the abbreviations and the like listed in Table 1 are as follows.
[(meth)acrylic acid ester 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, product name "Takenate D-101E")
B2: Aluminum trisacetylacetonate (manufactured by Soken Chemical 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: Methyltri-n-butylammonium bis(trifluoromethanesulfonyl)imide (ionic liquid)

3. Manufacture of adhesive sheet A heavy release type release sheet (manufactured by Lintec, product name: "SP-PET752150") prepared by applying the coating solution of the adhesive composition obtained in step 2 above to one side of a polyethylene terephthalate film with a silicone release agent. '') was coated with a knife coater. The coating layer was then heat-treated at 90° C. for 1 minute to form a coating layer.

Next, the coated layer on the heavy release type release sheet obtained above and a light release type release sheet (manufactured by Lintec, product name "SP-PET382120") in which one side of the polyethylene terephthalate film was released with a silicone release agent. are laminated so that the release-treated surface of the light-release release sheet is in contact with the coating layer, and cured for 7 days at 23°C and 50% RH to form a heavy-release release sheet/adhesive. A pressure-sensitive adhesive sheet having a structure of layer (thickness: 25 μm)/light release type release sheet was produced. The thickness of the adhesive layer is a value measured in accordance with JIS K7130 using a constant pressure thickness measuring device (manufactured by Techlock Co., Ltd., product name "PG-02").

4. Manufacture of laminate 4-1. Preparation of Substrate As a coating liquid for forming a hard coat layer, 100 parts by mass of polyfunctional (meth)acrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., product name "NK Ester A-DPH") (expressed in terms of solid content). (Hereinafter, the same applies to other components.), 4.3 parts by mass of 1-hydroxycyclohexylphenyl ketone as a photopolymerization initiator, and silica fine particles (manufactured by Fuji Silysia Chemical Co., Ltd., product name "Silohobic 702") , average particle size 4.1 μm), 0.01 part by mass of a leveling agent (manufactured by Toray Dow Corning, product name "SH28"), and silica nanoparticles (manufactured by Nissan Chemical Industries, Ltd., product name "MIBK-"). ST", average particle size: 10 nm) was mixed with 8.3 parts by mass and diluted with propylene glycol monomethyl ether to prepare a coating liquid with a solid content concentration of 30%.

The above 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 bar #10 and dried at 70° C. for 1 minute. Next, in a nitrogen atmosphere, ultraviolet rays were irradiated using a high-pressure mercury lamp at an illuminance of 200 mW/cm ² and a light amount of 300 mJ/cm ² to form a hard coat layer (acrylic hard coat layer) with a thickness of 1.5 μm. The thus obtained PET film with a hard coat layer (tensile modulus: 5.0 GPa, haze value: 4.0%) was used as a base material.

4-2. Preparation of protective film 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 are copolymerized by a solution polymerization method to obtain a (meth)acrylic acid ester polymer. was prepared. When the molecular weight of this (meth)acrylic acid ester polymer was measured by the method described below, it was found to have a weight average molecular weight (Mw) of 1.2 million.

100 parts by mass of the (meth)acrylic ester polymer obtained above (solid content equivalent; the same applies hereinafter) and 0.72 parts of an isocyanurate crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-170N") Part by mass and 1.0 part by mass of potassium hexafluorophosphate were mixed, sufficiently stirred, and diluted with toluene to obtain a coating solution of the 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. Thereafter, it was cured for 14 days under conditions of 23° C. and 50% RH to form a coating layer with a thickness of 15 μm (acrylic adhesive layer). The thus obtained PET film with an adhesive layer was used as a protective film.

4-3. Manufacture of laminate The protective film obtained in step 4-2 above was laminated to the hard coat layer of the base material obtained in step 4-1 via the adhesive layer of the protective film. Next, the easy-release type release sheet was peeled off from the pressure-sensitive adhesive sheet obtained in step 3 above, and the exposed pressure-sensitive adhesive layer was bonded to the PET film of the base material. In this way, a first laminate consisting of protective film/base material/adhesive layer/heavy release type release sheet was obtained.

The heavy release type release sheet was 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. Through the exposed adhesive layer, the second laminate is attached to 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 It was attached to each side of the ITO layer side of a transparent conductive film (manufactured by Oike Kogyo Co., Ltd., laminate of PET film and ITO layer (ITO-PET film), total thickness 125 μm). Then, it was autoclaved for 30 minutes at 50° C. and 0.5 MPa, and left for 24 hours at normal pressure, 23° C., and 50% RH. In this way, the second laminate (the base material in the second laminate corresponds to the first display member), the glass plate (1.1 mm/0.7 mm) or the ITO-PET film (the second A laminate was obtained in which the display body constituent members) were bonded together.

[Examples 2 to 17, Comparative Examples 1 to 7]
The type and proportion of each monomer constituting the (meth)acrylic acid ester polymer (A), the type and amount of the crosslinking agent (B), the type and amount of the antistatic agent (C), and the thickness of the adhesive layer. A pressure-sensitive adhesive sheet and a laminate were produced in the same manner as in Example 1, except that the thickness was 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") as a UV absorber was further blended into the adhesive composition. .

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

In Example 15 and Comparative Example 6, the adhesive layer of the laminate produced in the same manner as in Example 1 was irradiated with active energy rays (ultraviolet rays) through the protective film and the base material under the following conditions. Then, the adhesive layer was cured.

<Active energy ray irradiation conditions>
・Using a high-pressure mercury lamp ・Illuminance 200mW/cm ² , light intensity 1000mJ/cm ²
・UV illuminance/light meter uses “UVPF-A1” manufactured by Eye Graphics.

Here, the weight average molecular weight (Mw) mentioned above is the weight average molecular weight in terms of polystyrene measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement).
<Measurement conditions>
・Measuring device: Tosoh Corporation, HLC-8320
・GPC column (passed in the following order): TSK gel superH-H manufactured by Tosoh Corporation
TSK gel superHM-H
TSK gel superH2000
・Measurement solvent: Tetrahydrofuran ・Measurement temperature: 40℃

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

Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. Thereafter, the adhesive was taken out and air-dried for 24 hours at a temperature of 23°C and a relative humidity of 50%, and further dried in an oven at 80°C for 12 hours. After drying, the mass was weighed using a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. Let the mass at this time be M2. Gel fraction (%) is expressed as (M2/M1)×100. The results are shown in Table 2.

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

<Active energy ray irradiation conditions>
・Using a high-pressure mercury lamp ・Illuminance 200mW/cm ² , light intensity 1000mJ/cm ²
・UV illuminance/light meter uses “UVPF-A1” manufactured by Eye Graphics.

[Test Example 2] (Measurement of haze value)
The adhesive layers of the adhesive sheets manufactured in Examples and Comparative Examples were bonded to glass, and this was used as a sample for measurement. After performing the background measurement on the glass, the haze value ( %) was measured. The results are shown in Table 2.

[Test Example 3] (Measurement of total light transmittance)
The adhesive layers of the adhesive sheets manufactured in Examples and Comparative Examples were bonded to glass, and this was used as a sample for measurement. After background measurement was performed on the glass, the measurement sample was completely measured using a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., product name "NDH-5000") in accordance with JIS K7361-1:1997. Light transmittance (%) was measured. The results are shown in Table 2.

[Test Example 3] (Measurement of adhesive strength)
The easy-release type release sheet was peeled off from the adhesive sheets produced in Examples and Comparative Examples, and the exposed adhesive layer was replaced with a polyethylene terephthalate (PET) film having an easily adhesive layer (manufactured by Toyobo Co., Ltd., product name "PET A4300", A laminate of heavy release type release sheet/adhesive layer/PET film was obtained. The obtained laminate was cut to a width of 25 mm and a length of 100 mm, which was used as a sample.

Under an environment of 23°C and 50% RH, the heavy release type release 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 placed in an autoclave manufactured by Kurihara Seisakusho Co., Ltd. Pressure was applied at 0.5 MPa and 50° C. for 20 minutes. After that, the adhesive strength (N /25mm) was measured. The measurements were conducted under conditions other than those described here in accordance with JIS Z0237:2009. The results are shown in Table 2.

Note that the adhesive sheets of Example 15 and Comparative Example 6 were attached to soda lime glass in the same manner as above and pressurized in an autoclave, and then active energy rays ( After irradiation with ultraviolet light (UV), the adhesive strength was measured after being left for 24 hours in the same manner as above. The irradiation conditions for active energy rays were the same as in Test Example 1.

[Test Example 4] (Measurement of peeling force)
Samples (heavy release type release sheet/adhesive layer/PET film) were prepared in the same manner as in Test Example 3 for the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples. The PET film side of the sample was attached to a stainless steel plate using double-sided adhesive tape, and the sample was fixed to a universal tensile tester (manufactured by Orientech Co., Ltd., product name "Tensilon UTM-4-100"). Under conditions of a temperature of 23°C and 50% RH, a sample heavy release type release sheet was pulled in a 180° direction at a pulling speed of 300 mm/min in accordance with JIS Z0237:2009, and the heavy release type release sheet was attached to an adhesive layer. The force when peeled off was measured, and this was defined as the peeling force (gravitational peeling force; mN/25 mm). The results are shown in Table 2.

In addition, the pressure-sensitive adhesive sheets manufactured in Examples and Comparative Examples were cut into 25 mm width and 100 mm length, and these were used as samples. The heavy release type release sheet side of the sample was attached to a stainless steel plate using double-sided adhesive tape, and fixed to a universal tensile tester (manufactured by Orientech Co., Ltd., product name "Tensilon UTM-4-100"). Regarding the sample, the peeling force (light surface peeling force; mN/25 mm) when the light-release type release sheet was peeled from the adhesive layer was measured in the same manner as above. The results are shown in Table 2.

The light surface peel force was subtracted from the heavy surface peel force obtained above to calculate the peel force difference. The results are shown in Table 2.

[Test Example 5] (Measurement of surface resistivity)
The easy release type release sheet was peeled off from the adhesive sheets produced in Examples and Comparative Examples, and the surface resistivity of the exposed adhesive surface of the adhesive layer was measured in accordance with JIS K6911:2006. Specifically, in an environment of 23°C and 50% RH, the easy-release release sheet was peeled off using a resistivity measuring device (manufactured by Mitsubishi Analytech, product name: Hiresta UP MCP-HT450). After applying a voltage of 100 V for 10 seconds to the prepared adhesive sheet (100 mm x 100 mm), the surface resistivity (Ω/sq) of the adhesive surface of the adhesive layer was measured. The results are shown in Table 2.

[Test Example 6] (Measurement of volume resistivity)
Peel off the easy-release type release sheet from the adhesive sheets produced in Examples and Comparative Examples, and measure the adhesive surface of the exposed adhesive layer with a resistivity measuring device (manufactured by Mitsubishi Analytech, product name: Hiresta UP MCP-HT450 model). ) was attached on a stage for measurement. Next, the heavy release type release sheet was peeled off, and this was used as a measurement sample. The volume resistivity of the measurement sample was measured in accordance with JIS K6911:2006. Specifically, in an environment of 23° C. and 50% RH, a voltage of 100 V was applied to the adhesive layer (100 mm x 100 mm) for 10 seconds using the resistivity measuring device. The volume resistivity (Ω/sq) of the layer was measured. The results are shown in Table 2.

[Test Example 7] (Calculation of permittivity)
A 100 μm thick adhesive layer was formed on one side of a 50 μm thick polyethylene terephthalate film in the same manner as in the Examples and Comparative Examples, and a 50 μm thick polyethylene terephthalate film was laminated to the adhesive layer. It was cut into 50 mm x 50 mm.

The capacitance (C1) of the obtained laminate was measured using an impedance analyzer (manufactured by Hewlett-Packard Japan, "HP-4194A") at a measurement frequency of 0.1 MHz. Further, two sheets of the polyethylene terephthalate film with a thickness of 50 μm were stacked and cut into a size of 50 mm×50 mm, and the capacitance (C2) was measured in the same manner. Then, from the values of C1 and C2, the formula for calculating the series connected capacitor is 1/C1=1/C2+1/C3
Based on this, the capacitance (C3) of the adhesive was calculated. Based on this capacitance C3, the dielectric constant εs of the adhesive was calculated from the following 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: Capacitance of adhesive S: Area of adhesive layer d: Thickness of adhesive layer

[Test Example 8] (Measurement of resistance value)
The easy-release type release sheet was peeled off from the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was attached to a glass plate (soda lime glass, thickness 1.1 mm). Then, the heavy release type release sheet was peeled off from the adhesive layer to expose the adhesive layer, and a transparent conductive film (manufactured by Oike Kogyo Co., Ltd., a laminate of a PET film and an ITO layer (ITO-PET film), a total 125 μm thick) were laminated so that the ITO layer side was in contact with the adhesive layer to obtain a sample. Regarding the sample, the resistance value (Ω/sq; before durability) of the transparent conductive layer was measured using a non-contact resistance measuring device (manufactured by Napson Co., Ltd., product name "EC-80"). The results are shown in Table 2.

Further, the above sample was subjected to moist heat conditions of 85° C. and 85% RH for 500 hours (durability test), and the resistance value (Ω/sq; after durability) of the transparent conductive layer was measured in the same manner as above. The results are shown in Table 2.

Next, the resistance value change rate (%; (resistance value after durability/resistance value before durability) x 100), which is the ratio of the resistance value after durability to the resistance value before durability, was calculated, and based on the following criteria: , the resistance value change was evaluated. The results are shown in Table 2.
◎…Resistance value change rate is 150% or less 〇…Resistance value change rate is over 150% and 300% or less ×…Resistance value change rate is over 300%

[Test Example 9] (Measurement of peeling electrostatic voltage)
The protective film was manually peeled from the base material of the three types of laminates (25 mm x 100 mm) manufactured in Examples and Comparative Examples at a peeling speed of 2.0 m/min, and after 2 seconds of peeling, static electricity was removed. Using a measuring device (manufactured by Simco Japan Co., Ltd., product name "FMX-003"), measure the electrostatic potential (peeling charge voltage; kV) at a position 2.0 cm from the exposed surface of the glass plate or ITO-PET film. did. The results are shown in Table 2.

[Test Example 10] (Measurement of level difference tracking rate)
Ultraviolet curing ink (manufactured by Teikoku Ink Co., Ltd., product name "POS-911 Sumi") was applied to the surface of a glass plate (manufactured by NSG Precision, product name: "Corning Glass Eagle ) was screen printed in the shape of a picture frame (external dimensions: 90 mm long x 50 mm wide, 5 mm wide). Next, the printed ultraviolet curable ink is cured by irradiation with ultraviolet light (80 W/cm ² , 2 metal halide lamps, lamp height 15 cm, belt speed 10 to 15 m/min), and the steps caused by printing (height of steps) are cured. A glass plate with a step having a thickness of 1 μm, 5 μm, 10 μm, 20 μm, 40 μm, or 60 μm was produced.

The easy-release type release sheet was peeled off from the adhesive sheets produced in Examples and Comparative Examples, and the exposed adhesive layer was replaced with a polyethylene terephthalate (PET) film having an easily adhesive layer (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness). It was laminated onto an easily adhesive layer with a diameter of 100 μm. Next, the heavy release type release sheet was peeled off to expose the adhesive layer, and using a laminator (manufactured by Fujipla, product name "LPD3214"), each step was added so that the adhesive layer covered the entire surface of the frame-shaped print. Laminated on a glass plate. Thereafter, it was autoclaved for 30 minutes at 50° C. and 0.5 MPa, and left for 24 hours at normal pressure, 23° C., and 50% RH.

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

Next, it was stored for 500 hours under high temperature and high humidity conditions of 85° C. and 85% RH (durability test), and then the step followability was evaluated. Level difference followability is judged by whether or not the printing level difference is completely filled with the adhesive layer.If lifting or peeling is observed at the interface between the printing level difference and the adhesive layer, it is judged that the printing level difference cannot be followed. It is assumed that there was no such thing. Here, the step followability was evaluated as a step followability rate (%) expressed by the following formula. The results are shown in Table 2.
Level difference tracking rate (%) = {(Height of level difference that remained filled without lifting, peeling, etc. after durability test (μm))/(Thickness of adhesive layer)} x 100

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

The pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, in laminating a hard protective plate having a step and a desired display component in the production of a display.

DESCRIPTION OF SYMBOLS 1... Adhesive sheet 11... Adhesive layer 12a, 12b... Release sheet 2... Display body 21... First display body constituent member 22... Second display body constituent member 3... Print layer

Claims (15)

An adhesive sheet having an adhesive layer for bonding two display body constituent members to each other,
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,
An ITO-PET film in which a tin-doped indium oxide layer is formed on one side of a polyethylene terephthalate film having a thickness of 125 μm, the adhesive layer laminated on the tin-doped indium oxide layer of the ITO-PET film, and laminated on the adhesive layer. A base material having a 1.5 μm thick acrylic hard coat layer formed on one side of a 125 μm thick polyethylene terephthalate film, and a 38 μm thick polyethylene layer laminated on the hard coat layer of the base material. 2. From the base material in a laminate comprising a terephthalate film and a protective film on one side of which a 15 μm thick acrylic adhesive layer containing 0.98% by mass of potassium hexafluorophosphate was formed. The peeling voltage obtained by peeling at a peeling speed of 0 m/min and measuring the electrostatic potential at a position 2.0 cm from the exposed surface of the ITO-PET film after 2 seconds of peeling is 0.15 kV or less. An adhesive sheet characterized by: The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer has a step followability rate of 10% or more. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive sheet has an adhesive force of 1 N/25 mm or more to soda lime glass. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive is an active energy ray non-curable pressure-sensitive adhesive. The adhesive contains a crosslinked product of a (meth)acrylic acid ester polymer,
The (meth)acrylic acid ester polymer is characterized in that it 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. The adhesive sheet according to any one of claims 1 to 4. The adhesive contains a crosslinked product of a (meth)acrylic acid ester polymer,
The (meth)acrylic acid ester polymer according to any one of claims 1 to 5, characterized in that it contains a structural unit derived from a monomer containing a reactive functional group from 1% by mass to 30% by mass. adhesive sheet. The adhesive is formed by crosslinking an adhesive composition containing a (meth)acrylic acid ester polymer and a crosslinking agent,
A content of the crosslinking agent in the adhesive composition is 0.1 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the (meth)acrylic acid ester polymer. The adhesive sheet according to any one of 1 to 6. The adhesive sheet according to any one of claims 1 to 7, wherein the content of the antistatic agent in the adhesive is 0.1% by mass or more and 10% by mass or less. The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, wherein the antistatic agent is an ionic compound. The adhesive sheet according to claim 9, wherein the ionic compound is a nitrogen-containing onium salt or an alkali metal salt. The adhesive sheet according to claim 10, wherein the anion constituting the nitrogen-containing onium salt or the alkali metal salt is a sulfonylimide anion or a halogenated phosphate anion. The adhesive sheet includes two release sheets,
The pressure-sensitive adhesive sheet according to any one of claims 1 to 11, wherein the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets. a display body component;
Other display body constituent members,
A display body comprising an adhesive layer for bonding the one display body constituent member and the other display body constituent member to each other,
A display body characterized in that the adhesive layer is formed from the adhesive layer of the adhesive sheet according to any one of claims 1 to 12. The display body according to claim 13, wherein at least one of the one display body constituent member and the other display body constituent member has a step at least on a side bonded by the adhesive layer. . The display body according to claim 13 or 14, wherein both the one display body constituent member and the other display body constituent member are hard plates.

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