TWI812696B - Adhesive sheets and laminates - Google Patents

Abstract

An object of the present invention is to provide an adhesive sheet and a laminate that have excellent antistatic properties and exhibit good blistering resistance when two rigid boards are bonded together. The solution of the present invention is to provide an adhesive sheet 1, which has an adhesive layer 11 for bonding two hard boards 21 and 22 to each other. The adhesive constituting the adhesive layer 11 contains Antistatic agent, the gel fraction of the adhesive is more than 64%, the thickness of the adhesive layer 11 is more than 30 μm and less than 500 μm, and the adhesive force of the adhesive sheet 1 to soda lime glass is more than 18N/25mm.

Description

Adhesive sheets and laminates

The present invention relates to an adhesive sheet for laminating two hard boards and a laminated body obtained using an adhesive layer of the adhesive sheet.

In recent years, many touch panels that serve as both display devices and input means have been used as display panels for various electronic devices. The types of touch panels mainly include resistance mode, electrostatic capacitance type, optical type and ultrasonic type. Resistance mode includes analog resistance mode and matrix resistance mode. Capacitance type includes surface type and projection type.

Touch panels of portable electronic devices such as smartphones and tablet terminals, which have attracted recent attention, use many projected electrostatic capacitive devices. As a projection type electrostatic capacitive touch panel of such a portable electronic device, a liquid crystal display device (LCD) in which various optical components are laminated is mostly used.

As the main component constituting the above-mentioned liquid crystal display device, a liquid crystal cell is usually used. The liquid crystal cell usually has the alignment layer of two transparent electrode substrates formed with the alignment layer as the inner side, is arranged at a predetermined distance through a spacer, and the periphery is sealed and the liquid crystal is held between the two transparent electrode substrates. A thing made of materials. Usually, film-like polarizing plates are connected to each other through an adhesive layer on the outside of the two transparent electrode substrates of the liquid crystal unit.

However, since the above-mentioned polarizing plate has high electrical insulation, it is easy to generate static electricity. When the polarizing plate is bonded to a liquid crystal cell in a state where static electricity is generated in this way, the alignment of the liquid crystal molecules may be disordered.

Therefore, in order to obtain effective antistatic performance, there are proposals to add an antistatic agent to an adhesive composition (for example, Patent Documents 1 and 2). [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2007-316377 [Patent Document 2] Japanese Patent Application Publication No. 2009-155585

The problem to be solved by the invention

However, when the above-mentioned antistatic agent is added to an adhesive composition, the durability of the adhesive obtained is lower than usual.

On the other hand, a display panel is usually provided with a hard protective panel on the front side, and the protective panel is adhered to a hard member (hard board) such as the liquid crystal display device and a glass substrate through an adhesive layer.

From the viewpoint of weight reduction or safety, plastic boards are sometimes used as the above-mentioned protective panels. However, plastic boards are different from glass boards in that they produce exhaust or allow water vapor to pass through under high temperature and high humidity (hot and humid) conditions. Therefore, bubbles, floating, peeling, etc. are most likely to occur between the plastic board and the adhesive layer. Therefore, the adhesive layer is required to be resistant to foaming.

As mentioned above, in order to prevent the foaming resistance from deteriorating in the adhesive layer used to bond the two hard boards, it has not previously been considered to add an antistatic agent that would cause a decrease in durability.

The present invention was made in view of this actual situation, and its object is to provide an adhesive sheet and a laminate that can exhibit excellent antistatic properties and good blistering resistance when two hard boards are bonded together. means to solve problems

In order to achieve the above object, the first aspect of the present invention provides an adhesive sheet, which is an adhesive sheet having an adhesive layer for bonding two hard boards to each other. It is characterized in that: the adhesive constituting the adhesive layer contains Antistatic agent, the gel fraction of the adhesive is more than 64%, the thickness of the adhesive layer is more than 30 μm and less than 500 μm, and the adhesive force of the adhesive sheet to soda-lime glass is more than 18N/25mm (Invention 1).

According to the above invention (Invention 1), when two hard boards are bonded together, it has excellent antistatic properties, good blistering resistance, and excellent step followability.

In the above invention (Invention 1), the content of the antistatic agent in the adhesive agent is preferably 0.1% by mass or more and 10% by mass or less (Invention 2).

In the above inventions (Inventions 1 and 2), the antistatic agent is preferably an ionic compound (Invention 3).

In the above invention (Invention 3), the ionic compound is preferably a nitrogen-containing onium salt or an alkali metal salt (Invention 4).

In the above invention (Invention 4), the anion constituting the nitrogen-containing onium salt or the alkali metal salt is preferably a sulfonimide anion or a halogenated phosphoric acid anion (Invention 5).

In the above inventions (Inventions 1 to 5), the adhesive agent contains a (meth)acrylate polymer or a cross-linked product thereof, and the (meth)acrylate polymer contains a structure derived from a hydroxyl-containing monomer. Units or structural units derived from carboxyl group-containing monomers are preferred (Invention 6).

In the above invention (Invention 6), the content of the structural unit derived from the hydroxyl group-containing monomer in the (meth)acrylate polymer is preferably 10% by mass or more and 30% by mass or less (Invention 7).

In the above invention (Invention 6), the content of the structural unit derived from the carboxyl group-containing monomer in the (meth)acrylate polymer is preferably 3% by mass or more and 20% by mass or less (Invention 8).

In the above inventions (Inventions 1 to 8), the adhesive sheet is preferably provided with two release sheets, and the adhesive layer is preferably held by the release sheets in such a manner that it is in contact with the release surfaces of the two release sheets (Invention 9).

The second aspect of the present invention provides a laminated body, which is a laminated body including two hard plates and an adhesive layer sandwiched by the two hard plates. It is characterized in that the adhesive layer is made of the adhesive sheet (inventions 1 to 1). 9) is formed of an adhesive layer (Invention 10).

In the above invention (Invention 10), it is preferable that at least one of the hard boards includes a plastic board (Invention 11).

In the above-mentioned inventions (Inventions 10 and 11), it is preferable that at least one of the hard boards has a step on the surface on the adhesive layer side (Invention 12). Invention effect

The adhesive sheet and laminate system of the present invention have excellent antistatic properties and good blistering resistance when two rigid boards are bonded together.

Form used to implement the invention

Hereinafter, embodiments of the present invention will be described. [adhesive sheet] The adhesive sheet of this embodiment has an adhesive layer for bonding two hard boards to each other. The specific composition of the adhesive sheet and the rigid board will be described later.

The adhesive constituting the adhesive layer in this embodiment contains an antistatic agent and has a gel fraction of 64% or more. In addition, the thickness of the adhesive layer (measured in accordance with JIS K7130) of the two hard boards is 30 μm or more and 500 μm or less, and the adhesion force of the above-mentioned adhesive sheet to soda lime glass is 18N/25mm or more. . By satisfying these necessary conditions, this adhesive sheet can exhibit excellent antistatic properties and good blistering resistance when two hard boards are bonded together. That is, by containing an antistatic agent, the adhesive layer not only exhibits excellent antistatic properties, but also unexpectedly exhibits good foaming resistance. Specifically, even when a laminate in which a glass plate and a plastic plate are bonded using the adhesive layer is placed under high temperature and high humidity conditions (for example, 85°C, 85%RH, 72 hours), it can suppress the generation of bubbles and floating. Blistering, peeling, etc. In particular, by containing a predetermined antistatic agent described below, it becomes a product with more excellent foaming resistance than when it does not contain an antistatic agent.

Here, when two hard boards are bonded to each other, since the hard boards are hard and not flexible, the adhesive layer is attached to one of the hard boards. By placing the two hard boards in the vertical direction Press to make each hard board and the adhesive layer closely adhere to each other, thereby bonding the two hard boards to each other. In the adhesive sheet of this embodiment, since the thickness of the adhesive layer is within the above range, the above-mentioned bonding method can be used to bond two hard plates satisfactorily. Furthermore, since the thickness of the adhesive layer is within the above range, even if the surface of the hard board on the adhesive layer side has a step, the adhesive layer can absorb the step well.

As an antistatic agent, it is sufficient that it can exhibit the above-mentioned excellent antistatic properties and good foaming resistance. Examples thereof include ionic compounds, nonionic compounds, and the like, with ionic compounds being particularly preferred. The ionic compound may be liquid (ionic liquid) or solid (ionic solid) at room temperature. Here, in this specification, an ionic compound refers to a compound in which cations and anions are connected mainly by electrostatic attraction. Moreover, an antistatic agent may be used individually by 1 type, and may be used in combination of 2 or more types.

As the ionic compound, nitrogen-containing onium salts, sulfur-containing onium salts, phosphorus-containing onium salts, alkali metal salts or alkaline earth metal salts are preferred. From the viewpoint of foaming resistance, nitrogen-containing onium salts or alkali salts are preferred. Metal salts are particularly preferred. The nitrogen-containing onium salt is preferably an ionic compound composed of a nitrogen-containing heterocyclic cation and its relative anion.

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

On the other hand, suitable examples of the anions constituting the ionic compound include halogenated phosphoric acid anions or sulfonimide anions. Suitable examples of halogenated phosphate anions include hexafluorophosphate and the like. Suitable examples of the sulfonyl imine anion include bis(fluoroalkylsulfonyl)imide, bis(fluorosulfonyl)imide, and the like. The bis(fluoroalkylsulfonyl)imide may be bis(perfluoroalkylsulfonyl)imide, and particularly suitable examples thereof include bis(trifluoromethanesulfonyl)imide.

Specific examples of the nitrogen-containing onium salt having a pyridine ring and a halogenated phosphate anion include 1-butyl-4-methylpyridinium hexafluorophosphate and 1-hexyl-3-methylpyridinium hexafluorophosphate. , 1-hexyl-4-methylpyridinium hexafluorophosphate, 1-octylpyridinium hexafluorophosphate, 1-octyl-4-methylpyridinium hexafluorophosphate, 1-dodecylpyridinium Hexafluorophosphate, 1-tetradecylpyridinium hexafluorophosphate, 1-cetadecyldinium hexafluorophosphate, 1-dodecyl-4-methylpyridinium hexafluorophosphate, 1-tetradecane Base-4-methylpyridinium hexafluorophosphate, 1-hexadecyl-4-methylpyridinium hexafluorophosphate, etc. From the viewpoint of foaming resistance, as the nitrogen-containing onium salt having a pyridine ring and a halogenated phosphate anion, dialkylpyridinium hexafluorophosphate is preferred, and 1-hexyl-3-methylpyridinium hexafluorophosphate is preferred. Fluorophosphate or 1-octyl-4-methylpyridinium hexafluorophosphate are particularly preferred.

Specific examples of the nitrogen-containing onium salt having a pyridine ring and a sulfonyl imine anion include 1-decylpyridinium bis(fluorosulfonyl)imide and 1-ethylpyridinium bis(fluorosulfonium). acyl) amide imine, 1-butylpyridinium bis(fluorosulfonyl) amide imine, 1-hexylpyridinium bis(fluorosulfonyl) amide imine, tert-butyl-3-methylpyridine Onium bis(fluorosulfonyl)imide, 1-butyl-4-methylpyridinium bis(fluorosulfonyl)imide, 1-hexyl-3-methylpyridinium bis(fluorosulfonyl) )amide, 1-butyl-3,4-dimethylpyridinium bis(fluorosulfonyl)amide, 4-methyl-1-octylpyridinium bis(fluorosulfonyl)amide Amines etc. From the viewpoint of foaming resistance, as the nitrogen-containing onium salt having a pyridine ring and a sulfonyl imine anion, dialkylpyridinium bis(fluorosulfonyl)imide is preferred, and 4- Methyl-1-octylpyridinium bis(fluorosulfonyl)imide is particularly preferred. In particular, in order to improve the foaming resistance, the above-mentioned antistatic agent is preferred.

Specific examples of the nitrogen-containing onium salt having an imidazole ring include 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)amide imide and 1-propyl-3-methylimidazolium bis(fluorosulfonyl)amide. (Fluorosulfonyl)imide, 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-hexyl-3-methylimidazolium bis(fluorosulfonyl)imide Imine, 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, etc. From the viewpoint of foaming resistance, as the nitrogen-containing onium salt having an imidazole ring, dialkyl imidazolium bis(fluorosulfonyl)imide is preferred, and 1-ethyl-3-methyl Imidazolium bis(fluorosulfonyl)imide is particularly preferred.

Specific examples of the alkali metal salt include potassium bis(fluorosulfonyl)imide, lithium bis(fluorosulfonyl)imide, potassium bis(fluoromethanesulfonyl)imide, and lithium bis(fluoromethanesulfonyl)imide. (Fluoromethanesulfonyl)imide, potassium bis(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, etc. Among these, from the viewpoint of foaming resistance, potassium bis(fluorosulfonyl)amide imide or lithium bis(trifluoromethanesulfonyl)amide imide is preferred.

The lower limit of the content of the antistatic agent in the adhesive of this embodiment is preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and particularly preferably 0.5 mass% or more. After considering the durability test, From the viewpoint of suppressing an increase in resistance value, 1.5% by mass or more is more preferred. When the lower limit of the content of the antistatic agent is the above, the antistatic agent has more excellent antistatic properties and has better foaming resistance. On the other hand, the upper limit of the content of the antistatic agent is preferably 10 mass% or less, particularly preferably 9 mass% or less, and further preferably 8 mass% or less. By setting the upper limit of the content of the antistatic agent to the above-mentioned value, the antistatic agent has better foaming resistance.

The adhesive in this embodiment may be any one of acrylic adhesive, polyester adhesive, polyurethane adhesive, rubber adhesive, polysiloxane adhesive, etc. In addition, the adhesive may be any one of emulsion type, solvent type or solvent-free type, and may be any one of cross-linked type or non-cross-linked type. Among these, an acrylic adhesive having excellent adhesive properties, optical properties, etc. is preferred.

In addition, the acrylic adhesive may be an active energy ray-curing substance, an active energy ray-non-curing substance, a cross-linking substance, a non-cross-linking substance, or It is a combination of these. As an active energy ray non-hardening acrylic adhesive, a cross-linking type is particularly preferable, and a thermal cross-linking type is more preferable.

The adhesive in this embodiment preferably contains a (meth)acrylate polymer or a cross-linked product thereof. Furthermore, the (meth)acrylate polymer preferably has a structural unit derived from a hydroxyl group-containing monomer or a structural unit derived from a carboxyl group-containing monomer. In addition, in this specification, (meth)acrylic means both acrylic and methacrylic. The same applies to other similar terms. In addition, "polymer" is a concept that also includes "copolymer".

When the (meth)acrylate polymer has a structural unit derived from a hydroxyl-containing monomer, the content is preferably 10% by mass or more. A content of 12% by mass or more is particularly preferred, and a content of 15% by mass or more is particularly preferred. Furthermore, when the (meth)acrylate polymer contains a structural unit derived from a carboxyl group-containing monomer, the content is preferably 3% by mass or more, particularly preferably 5% by mass or more, and further preferably 8% by mass. The above is better. Thereby, the adhesive layer becomes one with excellent resistance to moisture and heat whitening. In addition, the so-called moist heat whitening refers to a phenomenon in which a display body containing an adhesive layer is exposed to high temperature and high humidity conditions, and when the adhesive layer is returned to normal temperature and humidity, the adhesive layer becomes white. Specifically, a laminate consisting of a glass plate and a plastic plate bonded with the above-mentioned adhesive layer is placed in high temperature and high humidity conditions (such as 85°C, 85%RH, 72 hours) and then returned to normal temperature. It can suppress the increase in haze value caused by whitening under normal humidity conditions.

On the other hand, when the above-mentioned (meth)acrylate polymer has a structural unit derived from a hydroxyl-containing monomer, the content is preferably 30 mass% or less, particularly preferably 25 mass% or less, and further preferably 20 mass%. % or less is better. Moreover, when the above-mentioned (meth)acrylate polymer contains a structural unit derived from a carboxyl group-containing monomer, the content is preferably 20 mass% or less, particularly preferably 15 mass% or less, and further preferably 12 mass%. The following is better. This makes it more resistant to foaming.

In addition, the details of the hydroxyl group-containing monomer and the carboxyl group-containing monomer will be described later.

The gel fraction of the adhesive in this embodiment is 64% or more, preferably 67% or more, from the viewpoint of foaming resistance. From the viewpoint of suppressing an increase in the resistance value after the durability test, the gel fraction is 70%. % or above is considered excellent. In addition, for an adhesive whose gel fraction is increased by irradiating active energy rays after being attached to the adherend, the increased gel fraction only needs to satisfy the above-mentioned lower limit. In addition, the gel fraction of the adhesive in this embodiment is preferably 90% or less, particularly preferably 85% or less, and further preferably 80% or less from the viewpoint of step followability. In addition, for an adhesive whose gel fraction is increased by irradiating active energy rays after being attached to the adherend, the increased gel fraction only needs to satisfy the above-mentioned upper limit. In addition, the method for measuring the gel fraction is as shown in the test examples described below.

The lower limit of the adhesive force of the adhesive sheet of this embodiment to soda-lime glass must be 18N/25mm or more, preferably 19N/25mm or more, and particularly preferably 20N/25mm or more. When the lower limit of the adhesive force of the adhesive sheet is as described above, the adhesive sheet has relatively good blistering resistance.

On the other hand, from the viewpoint of reworkability, the upper limit of the adhesive force is preferably 40N/25mm or less, more preferably 35N/25mm or less, and particularly preferably 30N/25mm or less.

Here, the above-mentioned adhesive force basically refers to the adhesive force measured using the 180-degree peeling method in accordance with JIS Z0237:2009. The specific test method is as shown in the test examples described later.

In this embodiment, the thickness of the adhesive layer must be 30 μm or more, and preferably 40 μmn or more, from the viewpoint of antistatic properties and blistering resistance. Furthermore, from the viewpoint of step followability, 50 μm or more is preferred. On the other hand, the thickness must be 500 μm or less, preferably 300 μm or less, particularly preferably 200 μm or less, and further preferably 150 μm or less.

The adhesive constituting the adhesive layer of this embodiment is, specifically, an adhesive combination of (meth)acrylate polymer (A), cross-linking agent (B), and antistatic agent (C). It is preferable that the composition is cross-linked (hereinafter referred to as "adhesive composition P").

(1) Each ingredient (1-1) (Meth)acrylate polymer (A) The (meth)acrylate polymer (A) preferably has a structural unit derived from a hydroxyl group-containing monomer or a structural unit derived from a carboxyl group-containing monomer. Thereby, the hydroxyl group derived from the hydroxyl-containing monomer or the carboxyl group derived from the carboxyl-containing monomer reacts with the cross-linking agent (B) to form a cross-linked structure (three-dimensional network structure) and can obtain the desired The adhesive of cohesion.

Examples of the hydroxyl-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and (meth)acrylic acid. Hydroxyalkyl (meth)acrylate, such as 2-hydroxybutyl ester, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and the like. In particular, in terms of reactivity with the cross-linking agent (B) and copolymerizability with other monomers, 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate is preferred. These may be used individually or in combination of 2 or more types.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Especially in terms of reactivity with the cross-linking agent (B) and copolymerizability with other monomers, acrylic acid is preferred. These may be used individually or in combination of 2 or more types.

The preferable ranges of the content of the structural units derived from the hydroxyl group-containing monomer and the content of the structural units derived from the carboxyl group-containing monomer in the (meth)acrylate polymer (A) are as described above. When the content of the structural unit derived from the hydroxyl group-containing monomer or the content of the structural unit derived from the carboxyl group-containing monomer is within the above range, the obtained adhesive layer has excellent moisture and heat whitening resistance. , and become a product with better foaming resistance.

The (meth)acrylate polymer (A) preferably contains a structural unit derived from an alkyl (meth)acrylate having 1 to 20 carbon atoms in an alkyl group. In this way, the obtained adhesive system can exhibit better adhesion. Moreover, the hard monomer mentioned later is excluded from this alkyl (meth)acrylate.

Examples of (meth)acrylic acid alkyl esters having 1 to 20 carbon atoms in the alkyl group include methyl acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and n-butyl (meth)acrylate. Ester, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, ( N-dodecyl methacrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, etc. These may be used individually or in combination of 2 or more types. Among the above, from the viewpoint of further improving the adhesion, the (meth)acrylate with the carbon number of the alkyl group is preferably 1 to 14. When further considering the step followability, the carbon number of the alkyl group is preferably A (meth)acrylate having an alkyl group having a carbon number of 4 to 10 is preferred, and a (meth)acrylate having an alkyl group having a carbon number of 5 to 8 is particularly preferred. Specifically, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isooctyl (meth)acrylate are preferred, and 2-ethylhexyl acrylate is particularly preferred.

The (meth)acrylate polymer (A) contains a structural unit of alkyl (meth)acrylate having 1 to 20 carbon atoms derived from an alkyl group in an amount of 30% by mass or more from the viewpoint of imparting adhesiveness. Preferably, the content is 40% by mass or more, and particularly preferably the content is 50% by mass or more. On the other hand, the upper limit is not particularly limited, but from the viewpoint of accepting structural units (monomer units) derived from other monomers, the upper limit is preferably 92 mass% or less, and particularly preferably 80 mass% or less. Furthermore, the content is preferably 70% by mass or less.

Moreover, it is preferable that the (meth)acrylate polymer (A) contains a structural unit derived from a hard monomer which is a homopolymer with a glass transition temperature (Tg) of 70° C. or higher. In addition, the hard monomer is excluded from the aforementioned hydroxyl group-containing monomer and carboxyl group-containing monomer. The (meth)acrylate polymer (A) contains a structural unit derived from the above-mentioned hard monomer, so that the cohesive force of the resulting adhesive is improved and has excellent durability. In particular, when a structural unit derived from a (meth)acrylate having 5 to 8 carbon atoms in an alkyl group is contained, the cohesion force tends to be low, so it is preferable to contain a structural unit derived from the above-mentioned hard monomer. The glass transition temperature (Tg) of the homopolymer as the above-mentioned hard monomer is preferably 75 to 200°C, and particularly preferably 80 to 180°C.

Examples of the hard monomer include methyl methacrylate (Tg 105°C), isocamphenyl acrylate (Tg 94°C), isocamphenyl methacrylate (Tg 180°C), acryloylmorpholine (Tg 145°C), Adamantyl acrylate (Tg115°C), adamantyl methacrylate (Tg141°C), dimethylacrylamide (Tg89°C), acrylamide (Tg165°C), etc. These may be used individually or in combination of 2 or more types.

Among the above-mentioned hard monomers, from the perspective of preventing adverse effects on other properties such as adhesion and transparency and further developing the performance of the hard monomer, methyl methacrylate and isocamphenyl acrylate are the most popular ones. and acryloylmorpholine are preferred, and methyl methacrylate is particularly preferred. On the other hand, the (meth)acrylate polymer (A) contains a structural unit derived from isocamphenyl acrylate in order to increase the gel fraction by hardening the adherend after being attached to it. Both structural units derived from acrylomorpholine are particularly preferred.

The (meth)acrylate polymer (A) preferably contains 10 to 45 mass % of structural units derived from the above-mentioned hard monomer, and particularly preferably 15 to 30 mass %. By containing 10% by mass or more of the structural unit derived from the above-mentioned hard monomer, a durability improvement effect obtained by the monomer unit can be expected. On the other hand, by setting the structural unit derived from the above-mentioned hard monomer to a content of 45% by mass or less, it is possible to prevent a relative shortage of other monomer units in the (meth)acrylate polymer (A), Moreover, the obtained adhesive has excellent adhesion and moisture-heat whitening resistance.

The (meth)acrylate polymer (A) may contain structural units derived from other monomers as necessary. As other monomers, in order not to interfere with the action of the hydroxyl-containing monomer, it is preferable to use a monomer that does not contain a reactive functional group. Examples of such other monomers include alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, and (meth)acrylic acid. (Meth)acrylates with aliphatic rings such as cyclohexyl ester, (meth)acrylic acid N,N-dimethylaminoethyl, (meth)acrylic acid N,N-dimethylaminopropyl, etc. have non-crossing properties. Linked tertiary amine (meth)acrylate, vinyl acetate, styrene, etc. These may be used individually or in combination of 2 or more types.

The (meth)acrylate polymer (A) may be solution polymerized, solvent-free polymerized, or emulsion polymerized. In particular, solution polymers obtained by solution polymerization are preferred. Through solution polymerization, it is easy to obtain a high molecular weight polymer and an adhesive with better foaming resistance.

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

The lower limit of the weight average molecular weight of the (meth)acrylate polymer (A) is preferably 200,000 or more, particularly preferably 300,000 or more, and further preferably 400,000 or more. When the lower limit of the weight average molecular weight of the (meth)acrylate polymer (A) is the above, the obtained adhesive system has more excellent foaming resistance.

Moreover, the upper limit of the weight average molecular weight of the (meth)acrylate polymer (A) is preferably 1 million or less, particularly preferably 900,000 or less, and further preferably 800,000 or less. When the upper limit of the weight average molecular weight of the (meth)acrylate polymer (A) is the above, the obtained adhesive system has more excellent step followability. In addition, the weight average molecular weight in this specification is a standard polystyrene-converted value measured using gel permeation chromatography (GPC).

Moreover, in the adhesive composition P, the (meth)acrylate polymer (A) may be used individually by 1 type, and may be used in combination of 2 or more types.

The content of the (meth)acrylate polymer (A) in the adhesive composition P of this embodiment is preferably 75 mass% or more, particularly preferably 85 mass% or more, and further preferably 95 mass% or more. good. Moreover, the content of the (meth)acrylate polymer (A) is preferably 99 mass% or less, particularly preferably 98 mass% or less, and further preferably 97 mass% or less. When the content of the (meth)acrylate polymer (A) is in the above range, it has more excellent foaming resistance.

(1-2) Cross-linking agent (B) The cross-linking agent (B) is a cross-linked structure capable of favorably forming a three-dimensional network structure in the (meth)acrylate polymer (A) by heating the adhesive composition P. Thereby, an adhesive having a predetermined cohesion force and better foaming resistance can be obtained.

The cross-linking agent (B) may be one that reacts with the reactive functional group (hydroxyl group or carboxyl group) of the (meth)acrylate polymer (A). Examples thereof include isocyanate-based cross-linking agents, Epoxy cross-linking agent, amine cross-linking agent, melamine cross-linking agent, acridine-cyclopropane cross-linking agent, hydrazine cross-linking agent, aldehyde cross-linking agent, oxazoline cross-linking agent, metal alkoxide Physical cross-linking agents, metal binder-based cross-linking agents, metal salt-based cross-linking agents, ammonium salt-based cross-linking agents, etc. Here, when the (meth)acrylate polymer (A) contains a hydroxyl-containing monomer as a constituent monomer unit, an isocyanate-based cross-linking agent (B) having excellent reactivity with hydroxyl groups is used. Combined agent is better. In addition, when the (meth)acrylate polymer (A) contains a carboxyl group-containing monomer as a constituent monomer unit, an epoxy cross-linking agent having excellent reactivity with carboxyl groups is used as the cross-linking agent (B). Combined agent is better. Moreover, the crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

The isocyanate cross-linking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, and isophorone. Diisocyanates, alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, and their biuret bodies and isocycyanurate bodies, and further combined with ethylene glycol, propylene glycol, neopentyl glycol, triglyceride It is an adduct of the reactants of compounds containing low molecular active hydrogen such as hydroxymethylpropane and castor oil. Especially from the viewpoint of reactivity with hydroxyl groups, trimethylolpropane-modified aromatic polyisocyanate, especially trimethylolpropane-modified toluene diisocyanate or trimethylolpropane-modified xylylene dimethyl diisocyanate is preferred.

Examples of the epoxy cross-linking agent include 1,3-bis(N,N-diepoxypropylaminemethyl)cyclohexane and N,N,N',N'-tetraepoxypropyl -Metaxylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol dialpoxypropyl ether, trimethylolpropane dialpoxypropyl ether, diepoxypropyl aniline, Diepoxypropylamine, etc. Especially from the viewpoint of reactivity with carboxyl groups, 1,3-bis(N,N-diepoxypropylaminemethyl)cyclohexane or N,N,N',N'-tetrakis Glycidyl-m-xylylenediamine is preferred.

The content of the cross-linking agent (B) in the adhesive composition P is based on 100 parts by mass of the (meth)acrylate polymer (A). The lower limit is preferably 0.01 parts by mass or more, and 0.05 parts by mass. Parts or more are particularly preferred, and 0.1 part by mass or more is more preferred. When the lower limit of the content of the cross-linking agent (B) is the above, a predetermined cross-linked structure can be formed and the resulting adhesive has more excellent foaming resistance. In addition, the upper limit of the content is preferably 1.0 parts by mass or less, particularly preferably 0.8 parts by mass or less, and further preferably 0.5 parts by mass or less. When the upper limit of the content of the cross-linking agent (B) is the above, the cross-linking density of the obtained adhesive can be made appropriate, and therefore it can have more excellent step following properties.

(1-3) Antistatic agent (C) The type of antistatic agent (C) and the content (mass %) of the antistatic agent in the adhesive are as described above. The content of the antistatic agent (C) in the adhesive composition P is based on 100 parts by mass of the (meth)acrylate polymer (A). The lower limit is preferably 0.5 parts by mass or more, and 1.0 parts by mass. The above is particularly preferred, and the content of 2.0 parts by mass or more is more preferred. In addition, the upper limit of the content is preferably 10 parts by mass or less, particularly preferably 8 parts by mass or less, and further preferably 5 parts by mass or less.

(1-4) Silane coupling agent (D) It is preferable that the adhesive composition P further contains a silane coupling agent (D). Thereby, when the adherend has a glass member, the adhesion between the obtained adhesive and the glass member is improved. Furthermore, even if the adherend is a plastic board, the adhesion between the obtained adhesive and the plastic board is improved. As a result, the adhesive system obtained has better foaming resistance.

The silane coupling agent (D) is an organosilicon compound having at least one alkoxysilane group in the molecule, and preferably has good compatibility with the (meth)acrylate polymer (A) and has light transmittance.

Examples of such a silane coupling agent (D) include polymerizable unsaturated group-containing ones such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane. Silicon compounds, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane Silicon compounds containing epoxy structures such as silane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, etc. Silicon compounds, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyl Amino group-containing silicon compounds such as dimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or at least one of these and methyltriethoxysilane, Condensates of alkyl group-containing silicon compounds such as ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These may be used individually by 1 type, and may be used in combination of 2 or more types.

The content of the silane coupling agent (D) in the adhesive composition P is preferably 0.01 parts by mass or more, particularly 0.05 parts by mass or more, based on 100 parts by mass of the (meth)acrylate polymer (A). Preferably, it is preferably 0.1 parts by mass or more. In addition, the content is preferably 1 part by mass or less, particularly preferably 0.5 part by mass or less, and further preferably 0.3 part by mass or less.

(1-5) Active energy ray curing ingredient (E) The adhesive composition P may further contain an active energy ray curing component (E). The adhesive containing the active energy ray curable component (E) has better step followability before hardening and the adhesive after hardening has better foaming resistance.

The active energy ray curable component (E) is cured by irradiation with active energy rays, and is not particularly limited as long as the above-mentioned effects can be obtained. It may be any of a monomer, an oligomer, or a polymer. is a mixture of these. In particular, polyfunctional acrylate-based monomers that can provide more excellent foaming resistance can be suitably cited.

Examples of the polyfunctional acrylate monomer include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate. acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxytrimethylacetate neopentyl glycol di(meth)acrylate, Dicyclopentyl di(meth)acrylate, caprolactone-modified dicyclohexenyl di(meth)acrylate, ethylene oxide-modified di(meth)acrylate phosphate, di(acryloxyethyl) methyl)isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis[4-(2-propenyloxyethane Oxy) phenyl] fluorine, etc. 2-functional type; trimethylolpropane tri(meth)acrylate, dipenterythritol tri(meth)acrylate, propionic acid modified dipenterythritol tri(meth)acrylate Meth)acrylate, neopentylerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, ginseng(acryloyloxyethyl)isocyanuric acid ester, ε-caprolactone modified ginseng-(2-(meth)acryloyloxyethyl)isocyanurate, etc. 3-functional type; diglyceryl tetra(meth)acrylate, neopentyl tetracycline The 4-functional type of alcohol tetra(meth)acrylate, etc.; the 5-functional type of propionic acid-modified dipenterythritol penta(meth)acrylate, etc.; dipenterythritol hexa(meth)acrylate, hexa(meth)acrylate, etc. Lactone-modified dipenterythritol hexa(meth)acrylate and other 6-functional types. Among the above, from the viewpoint of the foaming resistance of the obtained adhesive, bis(acryloxyethyl)isocyanurate and ginseng(acryloxyethyl)isoterpolymer are used. Cyanate, ε-caprolactone modified ginseng-(2-(meth)acryloyloxyethyl)isocyanurate and other multifunctional acrylates with an isocyanate structure in the molecule Preferably, it is a polyfunctional acrylate monomer with more than three functions and containing an isocyanurate structure in the molecule, and ε-caprolactone modified ginseng-(2-(methyl )acryloxyethyl)isocyanurate is particularly preferred. These may be used individually by 1 type, and may be used in combination of 2 or more types. Furthermore, from the viewpoint of compatibility with the (meth)acrylate polymer (A), the polyfunctional acrylate monosystem preferably has a molecular weight of less than 1,000.

The content of the active energy ray-curable component (E) in the adhesive composition P is higher than that of the (methyl) group from the viewpoint of improving the cohesive force of the resulting adhesive and having excellent foaming resistance. For 100 parts by mass of the acrylate polymer (A), the lower limit is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and particularly preferably 4 parts by mass or more. On the other hand, from the viewpoint of the effect of suppressing warpage, the upper limit of the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less, and 6 parts by mass or less. Parts by mass or less are better.

(1-6) Various additives The adhesive composition P may contain various additives commonly used in acrylic adhesives, such as adhesive agents, antioxidants, light stabilizers, softeners, fillers, refractive index adjusters, etc., as necessary. In particular, when the adhesive composition P contains an active energy ray curable component (E) and uses ultraviolet rays as active energy rays, 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 irradiation can be reduced.

Examples of such a photopolymerization initiator (E) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, and benzoin isopropyl ether. Butyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2 -Hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxyepoxyphenylketone, 2-methyl-1-[4-(methylthio)phenyl]-2-one Phin-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)one, diphenylketone, p-phenyldiphenylketone, 4,4' -Diethylaminodiphenylketone, dichlorodiphenylketone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methyl Base 9-oxosulfide𠮿 , 2-ethyl 9-oxosulfide𠮿 , 2-chloro-9-oxosulfide𠮿 , 2,4-dimethyl 9-oxosulfide𠮿 , 2,4-diethyl 9-oxosulfide𠮿 , benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligomeric [2-hydroxy-2-methyl-1[4-(1-methylvinyl) Phenyl]acetone], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc. These may be used individually or in combination of 2 or more types.

Among the above, a phosphine oxide-based photopolymerization initiator that easily cracks even when irradiated with ultraviolet rays through a plastic plate containing an ultraviolet absorber and easily and reliably hardens the adhesive is preferred. Specifically, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc. are used. good.

The content of the photopolymerization initiator in the adhesive composition P is based on 100 parts by mass of the active energy ray curable component (E). The lower limit is preferably 2 parts by mass or more, and particularly 4 parts by mass or more. Preferably, it is more than 6 parts by mass. Moreover, the upper limit of the content of the photopolymerization initiator is preferably 20 parts by mass or less, particularly preferably 18 parts by mass or less, and further preferably 15 parts by mass or less.

(2) Production of adhesive composition The adhesive composition P is prepared by producing a (meth)acrylate polymer (A) and mixing the obtained (meth)acrylate polymer (A), a cross-linking agent (B), and an antistatic agent (C). At the same time, a silane coupling agent (D), an active energy ray curable component (E), additives, etc. can be added as necessary to produce it.

The (meth)acrylate polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer using a common radical polymerization method. The polymerization of the (meth)acrylate polymer (A) is preferably carried out by a solution polymerization method using a polymerization initiator as necessary. However, the present invention is not limited to this, and polymerization can also be performed without a solvent. . Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like, and two or more types may be used in combination.

Examples of the polymerization initiator include azo compounds, organic peroxides, and the like, and two or more types may be used in combination. Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), and 1,1'-azobis(cyclohexane). Alkane 1-nitrile), 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 benzyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, and di-n-propyl peroxydicarbonate. , di(2-ethoxyethyl) peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxytrimethylacetate, peroxy(3,5,5-trimethyl Acetyl peroxide), dipropyl peroxide, diethyl peroxide, etc.

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

After obtaining the (meth)acrylate polymer (A), the cross-linking agent (B), the antistatic agent (C), and as needed are added to the solution of the (meth)acrylate polymer (A). The silane coupling agent (D), active energy ray curable component (E), additives, diluting solvent, etc. are thoroughly mixed to obtain a solvent-diluted adhesive composition P (coating solution). In addition, when any of the above components is used in a solid state or precipitates when mixed with other components in an undiluted state, the components may be separately dissolved or diluted in a diluting solvent beforehand. Mix with other ingredients.

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

The concentration and viscosity of the coating solution prepared in this way are not particularly limited as long as they are within the range that can be applied, and can be appropriately selected depending on the situation. For example, the adhesive composition P is diluted so that the concentration becomes 10 to 60% by mass. In addition, when obtaining a coating solution, the addition of a diluting solvent or the like is not necessary. When the adhesive composition P has a viscosity that enables coating, the diluting solvent does not need to be added. At this time, the adhesive composition P becomes a coating solution in which the polymerization solvent of the (meth)acrylate polymer (A) is directly used as the diluting solvent.

(3) Manufacturing of adhesives After the above adhesive composition P is applied to a desired object, an adhesive (adhesive layer) can be obtained by cross-linking.

Cross-linking of the adhesive composition P is performed by heat treatment. The drying process after application of the adhesive composition P can also serve as this heating process. The heating temperature for the heat treatment is preferably 50 to 150°C, and particularly preferably 70 to 120°C. In addition, the heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

After the heat treatment, a curing period of about 1 to 2 weeks at normal temperature (for example, 23°C, 50%RH) can also be set as necessary. If the aging period is necessary, the adhesive can be formed after the aging period has passed. If the aging period is not necessary, the adhesive can be formed after the heat treatment is completed.

By the above-described heat treatment (and aging), the (meth)acrylate polymer (A) can be fully cross-linked through the cross-linking agent (B). The adhesive layer system obtained in this way has excellent foaming resistance.

In addition, when the adhesive composition P contains an active energy ray-curable component (E), the adhesive composition P may be applied to a desired object as described above and heat-treated, and then irradiated with active energy. The ray hardens the adhesive composition P to form an adhesive (adhesive layer). However, it is preferable to adhere to the adherend in a state before irradiation with active energy rays and then irradiate active energy rays. As a result, the system has better step followability in the early stages.

(4) Physical properties of adhesive (adhesive layer) (4-1) Gel fraction The gel fraction of the adhesive constituting the adhesive layer of the adhesive sheet of this embodiment is as described above. Furthermore, when the adhesive composition P contains an active energy ray curable component (E), the gel fraction of the adhesive before active energy ray irradiation is preferably 20% or more, and more preferably 30% or more. Above 40% is particularly good. By satisfying the above-mentioned lower limit value, the coating film strength of the adhesive layer can be made sufficient. On the other hand, the gel fraction is preferably 63% or less, more preferably 58% or less, and particularly preferably 55% or less. By satisfying the above-mentioned upper limit, excellent step followability can be exhibited.

(4-2)Adhesion The adhesive force of the adhesive caustic soda in this embodiment to the lime glass is as described above. Moreover, when the adhesive composition P is an adhesive containing an active energy ray curing component (E), the adhesive force after active energy ray irradiation may satisfy the above value. The adhesive force system before active energy ray irradiation is not particularly limited.

(4-3) Haze plant The haze value of the adhesive layer of the adhesive sheet of this embodiment is preferably 3% or less, particularly preferably 1.5% or less, and further preferably 0.8% or less. When the haze value of the adhesive layer is 3% or less, the transparency is very high and it is suitable for optical applications (for displays). On the other hand, the lower limit of the haze value of the adhesive layer is not particularly limited. The lower limit value may be 0%, but is usually about 0.1% in terms of measurement accuracy and the like. Moreover, when the adhesive composition P contains the active energy ray curable component (E), it is preferable that the adhesive layer is placed before and after the active energy ray irradiation to satisfy the above haze value. Here, the haze value in this specification is a value measured in accordance with JIS K7136:2000.

(4-4) Surface resistivity: The surface of the exposed surface of the adhesive layer when a voltage of 100 V is applied to the adhesive sheet (adhesive layer/release sheet) of this embodiment for 10 seconds in an environment of 23°C and 50% RH. The upper limit of the resistivity is preferably 1.0×10 ¹³ Ω/sq or less, more preferably 5.0×10 ¹² Ω/sq or less, particularly preferably 1.0×10 ¹² Ω/sq or less, and further preferably 5.0× 10 ¹² Ω/sq or less is preferred. When the upper limit value of the surface resistivity is as described above, excellent antistatic properties can be exerted and the generation of static electricity can be satisfactorily suppressed when the release sheet is peeled from the adhesive sheet. Therefore, when the adhesive sheet is attached to an adherend (hard board), dust in the air and dust can be effectively suppressed from adhering to the adherend. The lower limit of the above-mentioned surface resistivity is not particularly limited, but generally it is preferably 1.0×10 ⁹ Ω/sq or above, particularly preferably 5.0×10 ⁹ Ω/sq or above, and further preferably 1.0×10 ¹⁰ Ω/sq or above. good. In addition, the surface resistivity of the adhesive layer was measured in accordance with JIS K6911, specifically as shown in the test examples described below.

(4-5) Changes in resistance value Usually, when a conductive layer and an adhesive layer are laminated in a state of being in contact with each other and put into a durable condition, an increase in the resistance value of the conductive layer can be observed. However, in the adhesive layer of this embodiment, although the reason is not yet clear, such an increase in resistance value can be suppressed to a minimum.

Specifically, the adhesive layer of this embodiment is attached to a glass plate, and a conductive layer (for example, a transparent conductive film composed of tin-doped indium oxide (ITO)) is laminated between the adhesive layer and the glass plate. The surface on which the glass plate contacts is the opposite surface. A base material (for example, a polyethylene terephthalate film) for holding the conductive layer is disposed on a surface of the conductive layer opposite to the surface in contact with the adhesive layer. The structure of this glass plate/adhesive layer/conductive layer/substrate was put into a humid heat condition of 85°C and 85% RH for 500 hours (durability test) and the resistance value of the conductive layer before and after durability was measured. At this time, the resistance value after endurance is preferably 3.5 or less times the resistance value before endurance (resistance value change: resistance value after endurance / resistance value before endurance), preferably 3 times or less, and 2.5 A ratio of less than 1.0 times is particularly good, and a ratio of 1.6 times or less is even better. On the other hand, the lower limit of the change in resistance value is not particularly limited, but is about 0.5 times. In addition, in the above test, the base material was used as a member to hold the conductive layer. It can be a glass plate or a resin plate. It is assumed that the results obtained are the same. The detailed test method for the change in resistance value is shown in the test examples described later.

(4-6) Peeling static voltage In an environment of 23°C and 50% RH, when the release sheet is manually peeled off from the adhesive layer of the adhesive sheet of this embodiment at a peeling speed of 2.0 m/min, the measured value is measured 5 seconds after peeling off. The electrostatic potential (peeling electrostatic voltage) at a position 2.0 cm from the exposed surface of the adhesive layer is preferably 1.0 kV or less, particularly preferably 0.5 kV or less, and further preferably 0.3 kV or less. When the peeling static voltage is as described above, static electricity is less likely to be generated when the peeling sheet is peeled from the adhesive layer, and dust and dust in the air caused by static electricity can be effectively suppressed from adhering to the adherend (hard board). The lower limit of the peeling electrostatic voltage is not particularly limited, but 0 kV is preferred. In addition, the details of the method for measuring the peeling electrostatic voltage are as shown in the test examples described below.

(4-7) Humid and heat whitening resistance In this embodiment, the moisture-heat whitening resistance of the adhesive layer can be quantitatively evaluated based on the haze value. Specifically, a laminate obtained by laminating a glass plate (soda lime glass) and a plastic plate (acrylic resin plate, thickness 1 mm) using the adhesive layer of this embodiment was tested at 85° C. and 85% RH. After the durability test of 72 hours of storage under hot and humid conditions, the haze value (%) before the durability test is subtracted from the haze value (%) of 24 hours of storage at room temperature and humidity at 23°C and 50% RH. When the value rises, it is better to be less than 3 percentage points, better to be less than 2 percentage points, especially better to be less than 1 percentage point, and further better to be less than 0.5 percentage points. When the haze value rises to the above level, even after being placed under humid and hot conditions, the rise in haze value is small and the whitening of the adhesive can be suppressed.

As mentioned above, a laminated body formed by bonding a glass plate and a plastic plate using an adhesive layer is compared to a laminated body formed by bonding two glass plates using an adhesive layer, because under hot and humid conditions, through the plastic plate The moisture in the layer is easy to condense in the laminate body, so it is easier to cause whitening in the adhesive layer. However, when an adhesive in which the content of the hydroxyl group-containing monomer or the carboxyl group-containing monomer is controlled as described above is used, even the above-mentioned laminate can exhibit excellent moisture and heat whitening resistance.

(4-8) step difference following rate In the adhesive layer of this embodiment, the lower limit value of the step following rate (%) represented by the following formula is preferably 5% or more, particularly preferably 10% or more, and further preferably 15% or more. In addition, the upper limit of the step following rate is not particularly limited, but generally 80% or less is preferred, and 70% or less is particularly preferred. Step following rate (%) = {(After the scheduled durability test, the height of the step without bubbles, floating, peeling, etc. and able to maintain the state after being filled (μm))/(Thickness of the adhesive layer)} × 100 In addition, the test method of step following rate is as shown in the test example mentioned later.

(5) The specific composition of the adhesive sheet The specific structure of an example of the adhesive sheet of this embodiment is shown in FIG. 1 . As shown in Figure 1, the adhesive sheet 1 of one embodiment is composed of two release sheets 12a and 12b, and the two release sheets 12a and 12b are in contact with the release surfaces of the two release sheets 12a and 12b. It is composed of a held-in adhesive layer 11. In addition, the term "peelable surface" of the release sheet in this specification means the surface of the release sheet that has releasability, including both the surface that has been subjected to release treatment and the surface that shows releasability without being subjected to release treatment.

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

As the release sheets 12a and 12b, for example, a polyethylene film, a polypropylene film, a polybutylene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, or a polyparaphenylene film can be used. Ethylene dicarboxylate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene‧(meth)acrylic acid copolymer Film, ethylene‧(meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. Moreover, these crosslinked films can also be used. Moreover, these laminated films may also be used.

The peeling surfaces of the above-mentioned peeling sheets 12a and 12b (especially the surfaces in contact with the adhesive layer 11) are preferably subjected to a peeling process. Examples of the release agent used in the release treatment include alkyd-based, polysiloxane-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. Moreover, among the release sheets 12a and 12b, it is preferable that one release sheet is a heavy release type release sheet with a large release force, and the other release sheet is a light release type release sheet with a small release force. .

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

(6) Manufacturing of adhesive sheets As an example of manufacturing the adhesive sheet 1, the above-mentioned coating solution of the adhesive composition P is applied to the peeling surface of one of the release sheets 12a (or 12b) and heat-treated to thermally cross-link the adhesive composition P. After forming the coating layer, the peeling surface of the other peeling sheet 12b (or 12a) is laminated on the coating layer. When the curing period is necessary, the curing period is performed by leaving it alone. When the curing period is unnecessary, the above-mentioned coating layer directly becomes the adhesive layer 11. Through the above steps, the adhesive sheet 1 can be obtained. The conditions for heat treatment and aging are as described above.

As another production example of the adhesive sheet 1, the coating solution of the adhesive composition P is applied to the peeling surface of one of the release sheets 12a and heat-treated to thermally cross-link the adhesive composition P to form a coating layer. The peeling sheet 12a with a coating layer is obtained. Furthermore, the coating liquid of the adhesive composition P is applied to the peeling surface of the other peeling sheet 12b, and heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer, thereby obtaining an additional coating layer. Peel-off sheet 12b. Furthermore, the peeling sheet 12a with the coating layer and the peeling sheet 12b with the coating layer are bonded together so that the two coating layers are in contact with each other. When the curing period is necessary, the curing period is left alone. When the curing period is unnecessary, the coating layer directly becomes the adhesive layer 11 . Through the above steps, the above-mentioned adhesive sheet 1 can be obtained. According to this production example, stable production can be achieved even when the adhesive layer 11 is thick.

As a method of applying the coating liquid of the adhesive composition P, for example, a rod coating method, a doctor blade method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, etc. can be used.

[Laminated body] A laminated body according to one embodiment of the present invention includes two hard plates and an adhesive layer held between the two hard plates. The adhesive layer is formed from the adhesive layer of the adhesive sheet. The laminate system is preferably an optical component, preferably a display body (display panel) or one of its components.

Here, in this embodiment, the hard board refers to a so-called non-flexible member that cannot be wound into a roll shape.

At least one of the above-mentioned hard boards preferably includes a plastic board. Plastic panels are different from glass panels in that they produce exhaust gas or penetrate water vapor under high temperature and high humidity conditions. Therefore, bubbles, floating, peeling, etc. are usually easily generated between the plastic board and the adhesive layer. However, in the laminate of this embodiment, by using the aforementioned adhesive sheet adhesive layer, it is possible to suppress the generation of bubbles, floating, and peeling even when placed under high temperature and high humidity conditions (for example, 85°C, 85%RH, 72 hours). Wait until it bubbles.

Furthermore, at least one of the above-mentioned hard boards may have a step on the surface on the adhesive layer side. In the laminate of this embodiment, the adhesive layer has excellent initial step followability and high temperature and high humidity conditions (for example, 85 ℃, 85%RH, 72 hours) after the step difference following the thing.

The specific structure as an example of the laminated body of this embodiment is shown in FIG. 2. As shown in Figure 2, the laminated body 2 of this embodiment is composed of the first hard plate 21, the second hard plate 22, and the position between them and is held by the first hard plate 21 and the second hard plate 22. Composed of adhesive layer 11. Moreover, in the laminated body 2 of this embodiment, the surface of the first hard plate 21 on the adhesive layer 11 side has a step. Specifically, it has a step caused by the presence or absence of the printing layer 3 .

The laminated body 2 may be, for example, a liquid crystal (LCD) display, a light emitting diode (LED) device, an organic electroluminescence (organic EL) device, an electronic paper, or any other member constituting a part of a display body, or the display body. itself. In addition, the display body may also be a touch panel.

The adhesive layer 11 in the laminated body 2 is the adhesive layer 11 of the adhesive sheet 1 itself, or the adhesive layer 11 of the adhesive sheet 1 is cured by irradiating active energy rays.

The first hard board 21 and the second hard board 22 are not particularly limited as long as only the adhesive layer 11 can be adhered to them. In addition, the first hard plate 21 and the second hard plate 22 may be made of the same material or different materials.

Examples of the first hard plate 21 and the second hard plate 22 include glass plates, plastic plates, metal plates, semiconductor plates, and laminates thereof, or plates such as display modules and solar cell modules. Shape hard products, etc. As mentioned above, at least one of the first hard board 21 and the second hard board 22 preferably contains a plastic board.

The plastic board is not particularly limited, and examples thereof include acrylic resin boards such as polycarbonate resin (PC) boards and polymethyl methacrylate resin (PMMA) boards, and acrylic resin layers such as polymethyl methacrylate resin layers. A plastic board, etc., in which a resin layer is laminated on a polycarbonate resin board. Furthermore, the polycarbonate resin plate may contain resins other than polycarbonate resin as its constituent material, and the acrylic resin plate may contain resin other than acrylic resin as its constituent material.

In addition, it is also preferable that the plastic board contains ultraviolet absorber. Plastic plates containing ultraviolet absorbers can protect various optical components such as transparent conductive layers and liquid crystal layers from being affected by ultraviolet rays. Therefore, plastic sheets containing ultraviolet absorbers are more likely to be used outdoors and can be suitably used in displays for vehicles and portable electronic equipment.

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

The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium and strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, and barium Borosilicate glass, etc.

In addition, when a glass plate is used as a protective plate located on the viewing side of the display, from the same viewpoint as a plastic plate containing ultraviolet absorbers, it is also preferable to provide an ultraviolet absorber layer on the glass plate, or to contain an ultraviolet absorber. Glass panels are also good.

The thickness of the glass plate is not particularly limited, but is usually 0.1~10mm, preferably 0.2~5mm, and more preferably 0.8~2mm.

In addition, various functional layers (transparent conductive film, metal layer, silicon oxide layer, hard coating layer, anti-glare layer, ultraviolet absorbing layer, etc.) can also be provided on one or both sides of the above-mentioned glass plate and plastic plate, and can also be formed There are metal wirings and optical components may be laminated. In addition, the transparent conductive film and metal layer can also be patterned.

Examples of the optical member include an anti-scatter film, a polarizing plate (polarizing film), a polarizing plate, a retardation plate (retardation film), a viewing angle compensation film, a brightness improvement film, a contrast improvement film, a liquid crystal polymer film, Diffusion film, semi-transmissive reflective film, transparent conductive film, etc. Examples of the anti-scatter film include a hard coat film in which a hard coat layer is formed on one side of a base film.

Examples of the display module include a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, and electronic paper. In addition, these display module sets are usually laminated with the above-mentioned glass plates, plastic plates, optical components, etc. For example, the LCD module is laminated with a polarizing plate and the polarizing plate forms a surface of the LCD module.

The material constituting the printing layer 3 is not particularly limited, and materials commonly used for printing can be used. The thickness of the printing layer 3, that is, the lower limit of the step height is preferably 3 μm or more, more preferably 7.5 μm or more, particularly preferably 10 μm or more, and most preferably 20 μm or more. When the lower limit value is equal to or higher than the above, it is possible to sufficiently ensure shielding properties such that the electrical wiring and the like cannot be viewed from the viewer side. In addition, the upper limit is preferably 100 μm or less, more preferably 80 μm or less, and particularly preferably 50 μm or less. When the upper limit value is the above-mentioned or lower value, it is possible to prevent the adhesive layer 11 from deteriorating in the step followability of the printing layer 3 . In addition, the printing layer 3 is usually formed into a frame shape on the adhesive layer 11 side of the hard board.

As an example of manufacturing the above-mentioned laminated body 2, the peeling sheet 12a of one side of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to the side of the first hard plate 21 where the printing layer 3 exists. noodle. At this time, since the adhesive layer 11 composed of an adhesive with a controlled gel fraction has excellent initial step followability, it is possible to suppress the occurrence of gaps and floating near the steps caused by the printing layer 3 .

Next, the release sheet 12b on the other side is peeled off from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to the second hard plate 22 to obtain a laminated body. In addition, as another example, the order of laminating the first hard plate 21 and the second hard plate 22 may be changed.

Since the above-mentioned adhesive layer 11 has excellent antistatic properties, the generation of static electricity can be well suppressed when peeling off the release sheets 12 a and 12 b from the adhesive sheet 1 . Therefore, when the adhesive sheet 1 is attached to the hard plates 21 and 22, dust in the air and dust can be effectively suppressed from adhering to the hard plates 21 and 22.

Here, when the adhesive composition P contains the active energy ray curable component (E), after the laminate of the first hard plate 21 and the adhesive layer 11 is bonded to the second hard plate 22, the laminate is bonded through the second hard plate 22. It is preferred that the first hard plate 21 and/or the second hard plate 22 irradiate the adhesive layer 11 with active energy rays to harden the adhesive layer 11 . This results in a product with more excellent foaming resistance.

Active energy rays refer to electromagnetic waves or charged particle rays that contain energy quanta. Specifically, they include ultraviolet rays, electron rays, etc. Among the active energy rays, ultraviolet rays that are easy to operate are particularly good.

Ultraviolet irradiation can be carried out using a high-pressure mercury lamp, light-curing H lamp, xenon lamp, etc. The amount of ultraviolet irradiation is preferably about 50 to 1000 mW/cm ² . In addition, the amount of light is preferably 50 to 10000 mJ/cm ² , more preferably 80 to 5000 mJ/cm ² , and particularly preferably 300 to 2000 mJ/cm ² . On the other hand, electron beam irradiation can be performed by an electron beam accelerator or the like, and the electron beam irradiation dose is preferably about 10 to 1000 krad.

Since the adhesive layer 11 of the above-mentioned laminate 2 has excellent foaming resistance, the laminate 2 can suppress the occurrence of bubbles in the adhesive layer 11 even after being left for 72 hours under conditions such as 85°C and 85% RH. Bubbles, floating, peeling, etc. occur at the interface with each hard plate 21, 22. In addition, since the adhesive layer 11 composed of an adhesive with a controlled gel fraction has excellent step followability even under high-temperature and high-humidity conditions, the laminate 2 can be maintained even at, for example, 85°C and 85R%H. Even after being left under the conditions for 72 hours, the generation of bubbles, floating, peeling, etc. near the step caused by the printing layer 3 can also be suppressed.

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

For example, one or both of the release sheets 12a and 12b of the adhesive sheet 1 may be omitted, and a required hard plate (optical member) may be laminated instead of the release sheets 12a and/or 12b. In addition, the first hard plate 21 may have steps other than the printing layer 3 . Furthermore, not only the first hard plate 21 but also the second hard plate 22 may have a step on the adhesive layer 11 side. [Example]

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

[Example 1] 1. Preparation of (meth)acrylate 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 to prepare a (meth)acrylate polymer. (A). When the molecular weight of the (meth)acrylate polymer (A) was measured using the method described below, it was found to be a weight average molecular weight (Mw) of 600,000.

2. Preparation of adhesive composition 100 parts by mass of the (meth)acrylate polymer (A) obtained in the above step 1 (solid content conversion value; the same below), trimethylolpropane-modified xylylene dimethyl as the cross-linking agent (B) 0.25 parts by mass of diisocyanate (manufactured by Soken Chemical Co., Ltd., product name "TD-75"), 4-methyl-1-octylpyridinium bis(fluorosulfonyl)imide (C) as an antistatic agent (C) C1) 3.0 parts by mass and 0.3 parts by mass of 3-glycidoxypropyltrimethoxysilane (D1) as the silane coupling agent (D) were mixed and thoroughly stirred, and diluted by using methyl ethyl ketone to obtain a coating solution of the adhesive composition.

Here, Tables 1 and 2 show each preparation (solid content conversion value) of the adhesive composition when the (meth)acrylate polymer (A) is 100 parts by mass (solid content conversion value). Moreover, the details of the abbreviations etc. described in Table 1 and Table 2 are as follows. [(Meth)acrylate polymer (A)] 2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate ACMO: N-Acrylylmorpholine IBXA: Isobornyl acrylate BA: n-butyl acrylate AA: acrylic [Crosslinking agent (B)] XDI: Trimethylolpropane-modified xylylene diisocyanate (manufactured by Soken Chemical Co., Ltd., product name "TD-75") TDI: Trimethylolpropane-modified toluene diisocyanate (manufactured by TOYOCHEM, product name "BHS8515") Epoxy system: 1,3-bis(N,N-diepoxypropylaminemethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "TETRAD-C") [Antistatic agent (C)] C1: 4-methyl-1-octylpyridinium bis(fluorosulfonyl)imide (ionic liquid) C2: 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (ionic liquid) C3: 1-hexyl-3-methylpyridinium hexafluorophosphate (ionic solid) C4: A mixture of potassium bis(fluorosulfonyl)imide and tetraethylene glycol dimethyl ether in a mass ratio of 1:1 (ionic solid) C5: Lithium bis(trifluoromethanesulfonyl)imide (ionic solid) [Silane coupling agent (D)] D1: 3-glycidoxypropyltrimethoxysilane D2: 3-glycidoxypropylmethyldiethoxysilane

3. Manufacturing of adhesive sheets The coating solution of the adhesive composition obtained in the above step 2 is applied using a knife coater to the heavy-peel type film that has been peeled off with a polysiloxane-based release agent on one side. After the peeling-processed surface of the peeling sheet (manufactured by LINTEC, product name "SP-PET752150") was heat-treated at 90° C. for 1 minute, a coating layer was formed.

Next, the coating layer on the heavy release type release sheet obtained above and the light release type release sheet (LINTEC) by peeling one side of the polyethylene terephthalate film using a polysiloxane release agent were used Made by the company, product name "SP-PET382120"), the release-treated surface of the light-peel release sheet is in contact with the coating layer, and is cured for 7 days at 23°C and 50% RH. , to manufacture an adhesive sheet composed of a heavy release release sheet/adhesive layer (thickness: 50 μm)/light release release sheet. In addition, the thickness of the adhesive layer is a value measured using a constant pressure thickness measuring device (manufactured by Teclock Corporation, product name "PG-02") in accordance with JIS K7130.

4. Manufacturing of laminated body Peel off the light-peel release sheet from the adhesive sheet obtained in step 3 above, and laminate the exposed adhesive layer to a plastic plate made by laminating a polymethyl methacrylate resin layer on a polycarbonate resin plate ( A plastic plate with an adhesive layer was obtained on the side surface of a polycarbonate resin plate made by Mitsubishi Gas Chemical Company, product name "UPILON‧SHEET MR58 U", containing ultraviolet absorber, thickness: 1mm).

The heavy-peel type release sheet was peeled off from the plastic plate with the adhesive layer obtained above, and the plastic plate was attached to a 70 mm × 150 mm soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd., thickness) through the exposed adhesive layer. :0.7mm). Furthermore, the autoclave treatment was performed under the conditions of 50°C and 0.5MPa for 30 minutes and left at normal pressure, 23°C, and 50% RH for 24 hours. In this manner, a laminated body (70 mm × 150 mm) in which a plastic plate (first hard plate) and a glass plate (second hard plate) were bonded together using an adhesive layer was obtained.

[Examples 2 to 9, Comparative Examples 1, 2, 5] The adhesive was produced in the same manner as in Example 1, except that the type of cross-linking agent (B), the type and blending amount of the antistatic agent (C), and the type of silane coupling agent (D) were changed as shown in Table 1. sheets and laminates.

[Example 10] 1. Preparation of (meth)acrylate polymer 60 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of isocamphenyl acrylate, 10 parts by mass of N-acrylylmorpholine, and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized using a solution polymerization method. (Meth)acrylate polymer (A) is prepared. When the molecular weight of the (meth)acrylate polymer (A) was measured using the method described below, it was found to be a weight average molecular weight (Mw) of 500,000.

Potassium bis(fluorosulfonyl)imide 2. Preparation of adhesive composition 100 parts by mass of the (meth)acrylate polymer (A) obtained in the above step 1, and trimethylolpropane-modified toluene diisocyanate (manufactured by TOYOCHEM, product name "BHS8515") as the cross-linking agent (B) ) 0.2 parts by mass, as the antistatic agent (C), 4.0 parts by mass, prepared by mixing potassium bis(fluorosulfonyl)imide and tetraethylene glycol dimethyl ether in a mass ratio of 1:1, as 0.3 parts by mass of 3-glycidoxypropyltrimethoxysilane (D1) as the silane coupling agent (D), and ε-caprolactone modified ginseng-(2-) as the active energy ray curing component (E) Acryloxyethyl)isocyanurate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-9300-1CL") 5.0 parts by mass, 2,4,6-trimethyl as a photopolymerization initiator 0.5 parts by mass of benzyl-diphenyl-phosphine oxide was mixed and thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of an adhesive composition.

3. Manufacturing of adhesive sheets An adhesive sheet was produced in the same manner as in Example 1, except that the coating solution of the adhesive composition obtained in step 2 was used.

4. Manufacturing of laminated body Peel off the light release type release sheet from the adhesive sheet obtained in step 3 above and laminate the exposed active energy ray-curable adhesive layer to a polymethyl methacrylate resin layer stacked on a polycarbonate resin plate. The surface of the polycarbonate resin plate side of the plastic plate (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "UPILON SHEET MR58U", ultraviolet absorber, thickness: 1 mm) was obtained to obtain a plastic plate with an adhesive layer.

The heavy-peel release sheet was peeled off from the plastic plate with the adhesive layer obtained above, and the plastic plate was attached to a 70 mm × 150 mm soda lime glass (Nippon Glass) through the exposed active energy ray curable adhesive layer. Company-made, thickness: 0.7mm). Furthermore, it was autoclaved at 50°C and 0.5MPa for 30 minutes and left at normal pressure, 23°C, and 50% RH for 24 hours.

Next, the active energy ray-curable adhesive layer is irradiated with active energy rays (ultraviolet) under the following conditions through a plastic plate to harden the adhesive layer. In this manner, a laminated body (70 mm × 150 mm) in which a plastic plate (first hard plate) and a glass plate (second hard plate) are bonded using the hardened adhesive layer was obtained.

>Active energy ray irradiation conditions> ‧High-pressure mercury lamp is used ‧Illuminance 200mW/cm ² , light quantity 1000mJ/cm ² ‧UV illuminance ‧The light meter is "UVPF-A1" made by EYEGRAPHICS

[Example 11, Comparative Examples 3 and 4] In addition to the types and proportions of each monomer constituting the (meth)acrylate polymer (A), the type and proportion of the cross-linking agent (B), and the type and proportion of the antistatic agent (C), are shown in Table 2 Except for changing the display, the same procedure as in Example 10 was carried out to produce an adhesive sheet and a laminated body.

Here, the weight average molecular weight (Mw) mentioned above is a weight average molecular weight in terms of polystyrene measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement). >Measurement conditions> ‧Measuring device: Made by TOSOH Co., Ltd., HLC-8320 ‧GPC column (pass in the following order): Made by TOSOH Co., Ltd. TSK gel super H-H TSK gel super HM-H TSK gel super H2000 ‧Measurement solvent: tetrahydrofuran ‧Measurement temperature: 40℃

(Test Example 1) (Measurement of Gel Fraction) (Measurement of gel fraction) The adhesive sheets obtained in the Examples and Comparative Examples were cut into a size of 80 mm × 80 mm, and the adhesive layer was wrapped in a polyester mesh (mesh size 200) and its mass was measured using a precision scale. The mass of the adhesive alone is calculated by subtracting the mass of the mesh alone. Let the mass at this time be M1.

Next, the adhesive covered with the polyester mesh was immersed in ethyl acetate at room temperature (23° C.) for 24 hours. The adhesive was then air-dried for 24 hours at a temperature of 23°C and a relative humidity of 50%, and dried in an oven at 80°C for 12 hours. After drying, its mass is weighed using a precision balance, and the mass of the adhesive alone is calculated by subtracting the mass of the mesh alone. Let the mass at this time be M2. The gel fraction (%) is expressed as (M2/M1)×100. The results are shown in Tables 3 and 4.

Furthermore, for the adhesive sheets (laminates) of Examples 10 and 11 and Comparative Examples 3 and 4, the adhesive layer was measured by irradiating active energy rays (ultraviolet; UV) through the plastic plate (irradiation from the side of the heavy-peel type release sheet). ) gel fraction before and after. The irradiation conditions of active energy rays are as follows.

>Active energy ray irradiation conditions> ‧High-pressure mercury lamp is used ‧Illuminance 200mW/cm ² , light quantity 1000mJ/cm ² ‧UV illuminance ‧The light meter is "UVPF-A1" made by EYEGRAPHICS

(Test Example 2) (Measurement of Haze Value) The light release type release sheet was peeled off from the adhesive sheet produced in Examples and Comparative Examples, and the exposed adhesive layer was attached to soda lime glass. The haze value (%) of the adhesive layer in this laminated body was measured using a haze meter (manufactured by Nippon Denshoku Industry Co., Ltd., product name "NDH-5000") in accordance with JIS K7136:2000. The results are shown in Tables 3 and 4.

In addition, for the adhesive sheets of Examples 10 and 11 and Comparative Examples 3 and 4, the haze value (%) was measured after the adhesive layer was irradiated with active energy rays (ultraviolet) (irradiated from the heavy-peel type release sheet side). The irradiation conditions of active energy rays are the same as those in Test Example 1.

[Test Example 3] (Measurement of Adhesion Force) The light release type release sheet was peeled off from the adhesive sheet produced in Examples and Comparative Examples, and the exposed adhesive layer was bonded to a polyethylene terephthalate (PET) film having an easy-adhesive layer (manufactured by Toyobo Co., Ltd. Named "PET A4300", thickness: 100 μm) to obtain a laminate of release sheet/adhesive layer/PET film. The obtained laminated body was cut into a width of 25 mm and a length of 100 mm, and this was used as a sample.

The heavy-peel type release sheet was peeled off from the above-mentioned sample in an environment of 23°C and 50% RH, and the exposed adhesive layer was attached to alkali-free glass (EAGLE The kettle was pressurized at 0.5MPa and 50°C for 20 minutes. Subsequently, after leaving it in an environment of 23° C. and 50% RH for 24 hours, a tensile testing machine (TENSILON manufactured by ORIENTEC Co., Ltd.) was used to measure the adhesive force (N/25 mm) at a peeling speed of 300 mm/min and a peeling angle of 180 degrees. ). Conditions other than those described here are measured in accordance with JIS Z0237:2009. The results are shown in Tables 3 and 4. In addition, "AT" in the table means peeling off at the interface between the easy-adhesion layer and the adhesive layer of the PET film.

In addition, for the adhesion of Examples 10 and 11 and Comparative Examples 3 and 4, the plastic plate (product name manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "UPILON SHEET MR58U" (containing ultraviolet absorber, thickness 1mm) was placed on the PET film, and the adhesive layer was irradiated with active energy rays (ultraviolet; UV) through the plastic sheet, and then left in the same manner as above for 24 hours. The adhesion force was also measured. The irradiation conditions of active energy rays are the same as those in Test Example 1.

[Test Example 4] (Measurement of Surface Resistivity) The light-peel release sheet was peeled off from the adhesive sheet produced in Examples and Comparative Examples, and the surface resistivity was measured based on JIS K6911 on the adhesive surface of the exposed adhesive layer. Specifically, a resistivity measuring device (manufactured by Mitsubishi Analytech Co., Ltd., product name "Hiresta UP MCP-H1450 type") was used in an environment of 23°C and 50% RH to measure the resistance of the adhesive sheet after peeling off the light-peel type release sheet. (100mm×100mm) Surface resistivity (Ω/sq) of the adhesive surface of the adhesive layer after applying a voltage of 100V for 10 seconds. The results are shown in Tables 3 and 4. In addition, those with a surface resistivity greater than 1.0×10 ¹⁴ Ω/sq are recorded as “over” in the table.

[Test Example 5] (Measurement of resistance value) The light-peel release sheet was peeled off from the adhesive sheet produced in Examples and Comparative Examples, and the exposed adhesive layer was attached to a glass plate (soda lime glass, thickness 1.1 mm). Furthermore, the heavy-peel type release sheet was peeled off from the above-mentioned adhesive layer to expose the adhesive layer, and a laminate of a transparent conductive film (manufactured by Oike Industrial Co., Ltd., a PET film and a transparent conductive layer (ITO), with a total thickness of 125 μm ), and the transparent conductive layer side is in contact with the adhesive layer to obtain a sample. For this 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, product name "EC-80"). The results are shown in Tables 3 and 4.

Furthermore, the laminates produced in Examples 1 to 9 and Comparative Examples 1, 2, and 5 were put into the wet heat conditions of 85° C. and 85% RH for 500 hours (durability test) and measured in the same manner as above, and then became transparent. Resistance value of the conductive layer (Ω/sq; after durability). Furthermore, the resistance value after endurance was calculated versus the resistance value before endurance (resistance value change: resistance value after endurance/resistance value before endurance). The results are shown in Table 3.

[Test Example 6] (Measurement of Peeling Electrostatic Voltage) The adhesive sheets produced in Examples and Comparative Examples were cut into 25 mm×100 mm and used as samples. In an environment of 23°C and 50% relative humidity, the peeling sheet was peeled off from the sample manually at a peeling speed of 2.0m/min. After peeling off for 5 seconds, an electrostatic tester (manufactured by SIMCO JAPAN Co., Ltd., product name " FMX-003") measures the electrostatic potential (peeling electrostatic voltage; kV) at a position 2.0cm from the exposed surface of the adhesive layer. The results are shown in Tables 3 and 4.

[Test Example 7] (Foreign matter adhesion test) In a non-clean room environment, the light release type release sheet was peeled off from the adhesive sheet produced in Examples and Comparative Examples and left for 10 hours in a state where the adhesive layer was exposed. Then, the number of foreign objects with a diameter of 30 μm or more attached to the exposed surface of the adhesive layer (20 cm × 20 cm) was counted. Based on the results, the degree of foreign matter adhesion was evaluated based on the following criteria. The results are shown in Tables 3 and 4. In addition, this test was carried out simultaneously under the same environment by juxtaposing the adhesive sheets of all Examples and Comparative Examples. ○: The number of attached foreign matters is less than 20. ×: The number of attached foreign objects is 20 or more.

[Test Example 8] (Evaluation of foaming resistance) The laminated bodies produced in Examples and Comparative Examples were stored under high temperature and high humidity conditions of 85° C. and 85% RH for 72 hours. Subsequently, the blistering resistance was evaluated based on the following criteria by visually confirming the state of the interface between the adhesive layer and the adherend (plastic plate, glass plate). The results are shown in Tables 3 and 4. ◎…No bubbles, floating or peeling at all. ○… 1~2 bubbles with a diameter less than 1mm are generated, but there is no floating or peeling. △… Three or more bubbles with a diameter less than 1mm are generated, but there is no floating or peeling. ×…Bubbles, floating, and peeling will occur.

[Test Example 9] (Measurement of step following rate) On the surface of a glass plate (manufactured by NSGPRECIS10N Co., Ltd., product name "Corning Glass EAGLE ) is screen printed in a frame shape (outline: 90mm in length x 50mm in width, 5mm in width). Next, irradiate ultraviolet rays (80W/cm, 2 metal halide lamps, lamp height 15cm, conveyor belt speed 10~15m/min) and use the above-mentioned ultraviolet curable ink after printing to harden it to create a step with printing (step difference) Height: any one of 7.5μm, 10μm, 20μm) and a glass plate with a step difference.

The light-peel release sheet was peeled off from the adhesive sheet produced in Examples and Comparative Examples, and the exposed adhesive layer was bonded to a polyethylene terephthalate (PET) film having an easy-adhesive layer (Toyobo Co., Ltd. Manufactured, product name "PET A4300", thickness: 100μm) easy-adhesion layer. Next, peel off the heavy-peel type release sheet to expose the adhesive layer, and use a laminating machine (manufactured by Fujipla, product name "LPD3214") to laminate each attachment so that the frame-shaped printing is fully covered with the adhesive layer. Different levels of glass panels. Subsequently, the autoclave treatment was performed under the conditions of 50°C and 0.5MPa for 30 minutes and left at normal pressure, 23°C, and 50% RH for 24 hours.

In addition, for the adhesive sheets of Examples 10 and 11 and Comparative Examples 3 and 4, a plastic plate (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "UPILON SHEET MR58U", containing ultraviolet absorber, thickness: 1 mm) was placed on PET On the film, the adhesive layer is irradiated with active energy rays (ultraviolet) through the plastic plate to harden the adhesive layer. The irradiation conditions of active energy rays are the same as those in Test Example 1.

Next, it was stored under high temperature and high humidity conditions of 85° C. and 85% RH for 72 hours (durability test), and then the step followability was evaluated. The step followability is judged by whether the printing step is completely filled with the adhesive layer. When bubbles, floating, peeling, etc. can be observed at the interface between the printing step and the adhesive layer, it is judged that the printing step cannot be followed. Here, the step following performance is evaluated in terms of the step following rate (%) represented by the following formula. The results are shown in Tables 3 and 4. Step following rate (%) = {(Height of step (μm) without bubbles, floating, peeling, etc. after the durability test and able to maintain the state of being filled)/(Thickness of the adhesive layer)} × 100

[Test Example 10] (Evaluation of Moisture and Heat Whitening Resistance) For the laminated bodies produced in Examples and Comparative Examples, the haze value (%) was measured in accordance with JIS K7136:2000 using a haze meter (manufactured by Nippon Denshoku Industry Co., Ltd., product name "NDH-5000").

Next, the above-mentioned laminated body was stored under humid heat conditions of 85° C. and 85% RH for 72 hours. Subsequently, it was returned to normal temperature and normal humidity of 23° C. and 50% RH, and the haze meter (manufactured by Nippon Denshoku Industry Co., Ltd., product name "NDH-5000") was used to measure the haze in accordance with JIS K7136:2000. Degree value (%). In addition, the haze value was measured within 30 minutes after returning the laminated body to normal temperature and normal humidity.

Based on the above results, the haze value before the moist heat condition was subtracted from the haze value after the moist heat condition to calculate the increase (percentage point) in the haze value after the moist heat condition. Those whose haze value increased to less than 1.0 percentage points after moist heat conditions were evaluated as having good moist heat whitening resistance (○), and those whose haze values increased to more than 1.0 percentage points after moist heat conditions were rated as poor moist heat whitening resistance (× ). The results are shown in Tables 3 and 4.

[Table 1]

[Table 2]

[table 3]

[Table 4]

It can be seen from Tables 3 and 4 that the adhesive sheet produced in the Example has excellent antistatic properties, blistering resistance and step followability, and also has excellent moisture and heat whitening resistance. industrial availability

The adhesive sheet of the present invention can be suitably used, for example, when manufacturing a display body, to bond a hard protective plate with a step to a required hard display component.

1‧‧‧Adhesive sheet 11‧‧‧Adhesive layer 12a, 12b‧‧‧Peel-off sheet 2‧‧‧Laminated body 3‧‧‧Printing layer 21‧‧‧No.1 Hard Board 22‧‧‧No.1 Hard Board

Figure 1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention. Figure 2 is a cross-sectional view of a laminated body according to an embodiment of the present invention.

1‧‧‧Adhesive sheet

11‧‧‧Adhesive layer

12a, 12b‧‧‧Peel-off sheet

Claims (11)

An adhesive sheet having an adhesive layer for bonding two hard boards to each other, characterized in that the adhesive constituting the adhesive layer is an acrylic adhesive and contains an antistatic agent of an ionic compound. , the gel fraction of the aforementioned adhesive agent is between 64% and less than 85%, the thickness of the aforementioned adhesive layer is between 30 μm and less than 500 μm, and the adhesion force of the aforementioned adhesive sheet to soda-lime glass is above 18N/25mm. The adhesive sheet described in Item 1 of the patent application, wherein the content of the antistatic agent in the adhesive is 0.1 mass% or more and 10 mass% or less. For the adhesive sheet described in item 1 of the patent application, the ionic compound is a nitrogen-containing onium salt or an alkali metal salt. The adhesive sheet described in Item 3 of the patent application, wherein the anion constituting the nitrogen-containing onium salt or the alkali metal salt is a sulfonyl imine anion or a halogenated phosphoric acid anion. The adhesive sheet as described in item 1 of the patent application, wherein the aforementioned adhesive contains a (meth)acrylate polymer or a cross-linked product thereof, and the aforementioned (meth)acrylate polymer is derived from a hydroxyl-containing monomer. Structural units of the body or structural units derived from carboxyl-containing monomers. The adhesive sheet described in claim 5, wherein the content of the structural unit derived from the hydroxyl-containing monomer in the (meth)acrylate polymer is 10 mass % or more and 30 mass % or less. The adhesive sheet described in Item 5 of the patent application, wherein the content of the structural unit derived from the carboxyl group-containing monomer in the (meth)acrylate polymer is 3% by mass or more and 20% by mass or less. Down. The adhesive sheet described in claim 1, wherein the adhesive sheet is provided with two release sheets, and the adhesive layer is held by the release sheets in contact with the release surfaces of the two release sheets. A laminated body, which is a laminated body including two hard plates and an adhesive layer held by the two hard plates. It is characterized in that the adhesive layer is made of any one of items 1 to 8 of the patent application. The adhesive sheet is formed by an adhesive layer. The laminated body according to claim 9, wherein at least one of the aforementioned hard boards contains a plastic board. The laminated body according to claim 9, wherein at least one of the hard boards has a step on the surface on the adhesive layer side.