Adhesive composition and adhesive sheet

Abstract

The present invention provides an adhesive sheet that exhibits excellent adhesion to an adherend even in a high-temperature environment or a humid heat environment. The present invention relates to an adhesive composition comprising: a (meth)acrylic polymer containing a (meth)acrylic monomer unit having a hydroxyl group and a (meth)acrylic monomer unit having a ring structure; and at least one selected from a cyclized polymerizable multifunctional monomer and a multifunctional monomer having a ring structure. The (meth)acrylic polymer has a glass transition temperature of 0°C or lower, and the content of a monomer unit having a nitrogen atom in the (meth)acrylic polymer is 0.1% by mass or lower.

Description

Technical Field

[0001] This invention relates to adhesive compositions and adhesive sheets. Background Technology

[0002] Previously, display devices such as liquid crystal displays (LCDs) and input devices such as touch panels, which were used in conjunction with display devices, were widely used. In these display devices and input devices, transparent adhesive sheets were used for attaching optical components, and also for bonding display devices to input devices.

[0003] When adhesive sheets are used in display devices, they are sometimes adhered to visually identifiable areas. In such cases, high transparency and resistance to damp heat are required for the adhesive sheets. For example, Patent Document 1 discloses an adhesive composition containing an acrylic polymer obtained by polymerizing monomers, wherein the monomers comprise (a) alkyl (meth)acrylate monomers having alkyl groups having 10 to 24 carbon atoms and (b) (meth)acrylate monomers having substituents capable of forming a cyclic ether structure during polymerization. In Patent Document 1, the acrylic polymer contains (c) an amide-containing monomer, thereby improving resistance to damp heat.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-66243 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] For adhesive sheets bonded to optical components, in addition to high transparency, excellent adhesion is also required. In recent years, optical components with adhesive sheets bonded to them have sometimes been used in harsh environments such as high temperature and high humidity, seeking to maintain excellent adhesion under such conditions. However, the adhesive sheet obtained in Patent Document 1 still has room for improvement in terms of adhesion to the adhered object in humid and hot environments.

[0009] Therefore, in order to solve the problems of this prior art, the inventors conducted research with the aim of providing an adhesive sheet that exhibits excellent adhesion to the adhered objects even in high temperature and humid environments.

[0010] Solution for solving the problem

[0011] Specifically, the present invention has the following structure.

[0012] [1] An adhesive composition comprising:

[0013] (Meth)acrylic polymers, comprising (meth)acrylic monomer units having hydroxyl groups and (meth)acrylic monomer units having ring structures; and

[0014] Selected from at least one of cyclizable polymerizable multifunctional monomers and multifunctional monomers with cyclic structures.

[0015] (Meth)acrylic acid polymers have glass transition temperatures below 0°C.

[0016] The content of hydroxyl-containing (meth)acrylic acid monomer units in the (meth)acrylic acid polymer is more than 20% by mass relative to the total mass of the (meth)acrylic acid polymer.

[0017] The content of cyclic (meth)acrylic acid monomer units in the (meth)acrylic acid polymer is more than 1% by mass relative to the total mass of the (meth)acrylic acid polymer.

[0018] The content of nitrogen-containing monomer units in (meth)acrylic polymers is less than 0.1% by mass.

[0019] [2] According to the adhesive composition of [1], wherein the (meth)acrylic monomer unit having a cyclic structure is a (meth)acrylic monomer unit having an alicyclic structure.

[0020] [3] The adhesive composition according to [1] or [2] further comprises a resin having a glass transition temperature of 20°C or higher.

[0021] [4] The adhesive composition according to any one of [1] to [3] further comprises a multifunctional monomer that does not have a cyclic structure and does not undergo cyclization.

[0022] [5] The adhesive composition according to any one of [1] to [4] further comprises a monofunctional monomer having a cyclic structure.

[0023] [6] The adhesive composition according to any one of [1] to [5] further comprises a silane coupling agent.

[0024] [7] The adhesive composition according to any one of [1] to [6] further comprises a photopolymerization initiator.

[0025] [8] An adhesive sheet formed from any one of the adhesive compositions described in [1] to [7].

[0026] The effects of the invention

[0027] According to the present invention, it is possible to obtain an adhesive sheet that exhibits excellent adhesion to the adhered objects even under high temperature and humid conditions. Attached Figure Description

[0028] Figure 1 This is a schematic diagram showing the cross-section of an adhesive sheet with a release tab. Detailed Implementation

[0029] The present invention will now be described in detail. The descriptions of the technical features described below are sometimes based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. It should be noted that the numerical range indicated by “~” in this specification refers to the range including the values ​​recorded before and after the “~” as the lower and upper limits.

[0030] It should be noted that in this specification, "(meth)acrylic acid" refers to both acrylic acid and methacrylic acid, or either one. Additionally, in this specification, "monomer" and "polymer" have the same meaning.

[0031] (Adhesive composition)

[0032] This invention relates to an adhesive composition comprising: a (meth)acrylic polymer containing hydroxyl-containing (meth)acrylic monomer units and cyclic (meth)acrylic monomer units; and at least one selected from cyclizable polyfunctional monomers and cyclic polyfunctional monomers. Here, the glass transition temperature of the (meth)acrylic polymer is below 0°C, and the content of hydroxyl-containing (meth)acrylic monomer units in the (meth)acrylic polymer is 20% by mass or more relative to the total mass of the (meth)acrylic polymer. Furthermore, the content of cyclic (meth)acrylic monomer units in the (meth)acrylic polymer is 1% by mass or more relative to the total mass of the (meth)acrylic polymer, and the content of nitrogen-containing monomer units in the (meth)acrylic polymer is 0.1% by mass or less.

[0033] With the above-described configuration, the adhesive sheet formed by the adhesive composition of the present invention exhibits excellent adhesion to the adhered objects even under high-temperature and humid environments. Specifically, when the adhesive sheet formed by the adhesive composition of the present invention is adhered to a polycarbonate sheet or float glass, and after standing for 30 minutes in a constant temperature and humidity chamber at 95°C, a constant load test is performed using a 100g weight. If peeling of the adhesive sheet is suppressed, the adhesion under high-temperature conditions can be evaluated as good. Furthermore, when the adhesive sheet formed by the adhesive composition of the present invention is adhered to a polycarbonate sheet or float glass, and after standing for 60 minutes in a constant temperature and humidity chamber at 85°C and 85% relative humidity, a constant load test is performed using a 100g weight. If peeling of the adhesive sheet is suppressed, the adhesion under humid environments can be evaluated as good.

[0034] Furthermore, the adhesive sheet formed from the adhesive composition of the present invention exhibits excellent resistance to degassing. Specifically, even when the adhesive sheet formed from the adhesive composition of the present invention is adhered to a substrate such as a polycarbonate sheet and left to stand at a high temperature for a specified time or longer, the formation of bubbles and peeling between the adhesive sheet and the substrate are suppressed, indicating good resistance to degassing.

[0035] Furthermore, the adhesive sheet formed from the adhesive composition of the present invention exhibits excellent lightfastness (weather resistance). Specifically, after bonding glass plates to both sides of the adhesive sheet formed from the adhesive composition of the present invention, and then placing the resulting laminate on a Super Xenon Weather Meter SX75 manufactured by Suga Test Instruments and irradiating it with a specified light (300-400 nm) for 300 hours, the increase in b* value is suppressed, indicating good lightfastness (weather resistance). In this way, yellowing of the adhesive sheet formed from the adhesive composition of the present invention is suppressed, and it exhibits high transparency; therefore, it is particularly preferred for optical bonding applications.

[0036] <(meth)acrylic acid polymers>

[0037] The adhesive composition contains a (meth)acrylic polymer, wherein the (meth)acrylic polymer contains (meth)acrylic monomer units having hydroxyl groups and (meth)acrylic monomer units having cyclic structures, and has a glass transition temperature of 0°C or lower. The content of the (meth)acrylic monomer units having hydroxyl groups in the (meth)acrylic polymer is 20% by mass or more relative to the total mass of the (meth)acrylic polymer, and the content of the (meth)acrylic monomer units having cyclic structures in the (meth)acrylic polymer is 1% by mass or more relative to the total mass of the (meth)acrylic polymer. Furthermore, the content of monomer units having nitrogen atoms in the (meth)acrylic polymer is 0.1% by mass or less.

[0038] Examples of (meth)acrylic acid monomers containing hydroxyl groups include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and polyalkylene glycol mono(meth)acrylate. Preferably, at least one monomer selected from 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate is used.

[0039] The content of hydroxyl-containing (meth)acrylic monomer units in the (meth)acrylic polymer should be 20% by mass or more, preferably 25% by mass or more, relative to the total mass of the (meth)acrylic polymer. Furthermore, the content of hydroxyl-containing (meth)acrylic monomer units in the (meth)acrylic polymer is preferably 50% by mass or less relative to the total mass of the (meth)acrylic polymer. By setting the content of hydroxyl-containing (meth)acrylic monomer units within the above range, the adhesion and degassing resistance of the adhesive sheet under high-temperature and humid conditions can be more effectively improved.

[0040] (Meth)acrylic acid polymers contain cyclic (meth)acrylic acid monomer units. The cyclic (meth)acrylic acid monomers are preferably (meth)acrylic acid monomers with alicyclic or aromatic rings, more preferably (meth)acrylic acid monomers with alicyclic rings. Examples of alicyclic rings include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cycloundecane, cyclododecane, norbornene, norbornadiene, dicyclopentane, tetrahydrofuran, and tetrahydropyran. It should be noted that the alicyclic ring may have a spiro structure. Examples of aromatic rings include benzene, naphthalene, anthracene, pyridine, furan, benzofuran, pyrrole, thiophene, imidazole, and oxazole. The cyclic structure is preferably alicyclic, and particularly preferably selected from at least one of cyclohexane, dicyclopentane, isoboronane, and benzene. It should be noted that the above-mentioned cyclic structure may optionally further have substituents. Examples of substituents include those selected from halogen atoms, haloalkyl, alkyl, alkenyl, acyl, hydroxyl, hydroxyalkyl, alkoxy, aryl, heteroaryl, alicyclic, cyano, epoxy, oxetyl, mercapto, amino, (meth)acryloyl, etc.

[0041] Examples of cyclic (meth)acrylic monomers include cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, phenoxyethyl (meth)acrylate, 3-phenoxybenzyl (meth)acrylate, and O-phenylphenoxyethyl (meth)acrylate. The content of cyclic (meth)acrylic monomer units in the (meth)acrylic polymer is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. Furthermore, the content of cyclic (meth)acrylic monomer units in the (meth)acrylic polymer is preferably 30% by mass or less. By setting the content of cyclic (meth)acrylic monomer units within the above range, the adhesion and degassing resistance of the adhesive sheet can be improved more effectively.

[0042] The glass transition temperature of (meth)acrylic polymers can be below 0°C, preferably below -10°C, more preferably below -20°C, and even more preferably below -30°C. The lower limit of the glass transition temperature of (meth)acrylic polymers is not particularly limited, but is preferably above -80°C for example.

[0043] It should be noted that the glass transition temperature of (meth)acrylic acid polymers can be calculated using the following FOX formula.

[0044] 1 / Tgp=W1 / Tg1+W2 / Tg2+···+Wn / Tgn

[0045] Tgp is the glass transition temperature of the acrylic polymer, Wn is the weight fraction of each monomer, and Tgn is the glass transition temperature when each monomer is made into a homopolymer.

[0046] The weight-average molecular weight of the (meth)acrylic acid polymer is preferably greater than 10,000, more preferably 100,000 or more, and even more preferably 200,000 or more. Furthermore, the weight-average molecular weight of the (meth)acrylic acid polymer is preferably less than 2 million, more preferably less than 1.5 million, and even more preferably less than 1.2 million. It should be noted that the weight-average molecular weight of the (meth)acrylic acid polymer refers to the value obtained by gel permeation chromatography (GPC), using a standard curve prepared with a standard polystyrene of known molecular weight, and converting the value using that standard curve. Commercially available (meth)acrylic acid polymers or polymers synthesized by known methods can be used.

[0047] In addition to monomer units containing hydroxyl groups, (meth)acrylic polymers may also contain alkyl (meth)acrylic ester units. Examples of alkyl (meth)acrylic esters include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate.

[0048] When the (meth)acrylate polymer contains an alkyl (meth)acrylate unit, the number of carbon atoms in the alkyl (meth)acrylate is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. Alternatively, the number of carbon atoms in the alkyl (meth)acrylate can be 24 or less, 20 or less, 18 or less, 15 or less, 12 or less, or 9 or less. By setting the number of carbon atoms in the alkyl (meth)acrylate within the above ranges, the adhesion and degassing resistance of the adhesive sheet can be improved more effectively.

[0049] In addition to (meth)acrylic acid monomer units with hydroxyl groups, (meth)acrylic acid monomer units with crosslinking functional groups may also be contained. Examples of crosslinking functional groups in (meth)acrylic acid monomers include amide groups, amino groups, thiol groups, isocyanate groups, epoxy groups, silanol groups, and carboxylic acid groups. The content of (meth)acrylic acid monomer units with crosslinking functional groups in the (meth)acrylic acid polymer is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. By setting the content of (meth)acrylic acid monomer units with crosslinking functional groups in the (meth)acrylic acid polymer to the above range, the adhesion between the adhesive sheet and the adhered object can be improved more effectively.

[0050] The content of (meth)acrylic acid monomer units having carboxylic acid groups in the (meth)acrylic acid polymer can be less than 0.1% by mass, and less than 0.01% by mass. This means that the (meth)acrylic acid polymer substantially does not contain (meth)acrylic acid monomer units having carboxylic acid groups. That is, the (meth)acrylic acid polymer contained in the adhesive composition of the present invention does not contain (meth)acrylic acid monomer units having carboxylic acid groups, and the resulting adhesive composition can be an acid-free adhesive composition.

[0051] (Meth)acrylic polymers may contain other monomer units as needed. These other monomers are only required to copolymerize with the aforementioned monomer components; examples include vinyl acetate, vinyl chloride, and ethyl vinyl ether. The content of other monomer units in the (meth)acrylic polymer is preferably 10% by mass or less, more preferably 5% by mass or less.

[0052] The content of nitrogen-containing monomer units in the (meth)acrylic acid polymer is less than 0.1% by mass, preferably less than 0.01% by mass. This means that the (meth)acrylic acid polymer substantially does not contain nitrogen-containing monomer units. By making the (meth)acrylic acid polymer substantially free of nitrogen-containing monomer units, the adhesion and light resistance (weather resistance) of the adhesive sheet can be improved more effectively.

[0053] The adhesive composition may contain an acrylic syrup A comprising a (meth)acrylic polymer. Here, acrylic syrup A comprises at least the (meth)acrylic polymer and monomers constituting the (meth)acrylic polymer. Therefore, the adhesive composition may contain not only the (meth)acrylic polymer but also monomers constituting the (meth)acrylic polymer. It should be noted that when acrylic syrup A contains monomers constituting the (meth)acrylic polymer, these monomers are polymerized during the process of manufacturing the adhesive sheet to form the (meth)acrylic polymer.

[0054] <Tackifying Resin>

[0055] The adhesive composition may further comprise a resin with a glass transition temperature of 20°C or higher. In this invention, the resin with a glass transition temperature of 20°C or higher functions as a tackifying resin (tackifier). By including a tackifying resin in addition to a (meth)acrylic polymer in the adhesive composition, the compatibility of the components in the adhesive composition is improved, and the adhesive sheet formed from the adhesive composition exhibits superior adhesion, degassing resistance, and light resistance (weather resistance).

[0056] The glass transition temperature of the resin (tackifying resin) having a glass transition temperature of 20°C or higher is preferably 30°C or higher, more preferably 40°C or higher, and even more preferably 50°C or higher. Furthermore, the glass transition temperature of the tackifying resin is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 150°C or lower. By setting the glass transition temperature of the tackifying resin within the above-mentioned range, the adhesion of the adhesive sheet to the adhered object can be improved.

[0057] The weight-average molecular weight of the tackifying resin is preferably 3000 or more, more preferably 3200 or more, and even more preferably 3500 or more. Furthermore, the weight-average molecular weight of the tackifying resin is only required to be 10000 or less, more preferably 9000 or less, and even more preferably 8000 or less. The weight-average molecular weight of the tackifying resin refers to the value obtained by measuring using gel permeation chromatography (GPC), preparing a standard curve using standard polystyrene with a known molecular weight, and converting the value using that standard curve. Commercially available resins or resins synthesized by known methods can be used as such.

[0058] The tackifying resin preferably does not have substantially any functional groups. In this case, the tackifying resin does not form a cross-linked structure with the aforementioned (meth)acrylic polymer.

[0059] The tackifying resin may contain monomer units having alicyclic rings. When the tackifying resin contains monomer units having alicyclic rings, the number of carbon atoms constituting the alicyclic ring is preferably 6 or more. Examples of alicyclic rings with 6 or more carbon atoms include cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cycloundecane, cyclododecane, norbornene, norbornadiene, and dicyclopentane.

[0060] As monomers with alicyclic rings, isobornyl acrylate, dicyclopentyl acrylate, dicyclopentenyl acrylate, etc. are preferred.

[0061] When the tackifying resin contains alicyclic monomer units, the content of alicyclic monomer units relative to the total mass of the tackifying resin is preferably 5% by mass or more, more preferably 10% by mass or more. Furthermore, the content of alicyclic monomer units relative to the total mass of the tackifying resin is preferably 90% by mass or less, more preferably 80% by mass or less. By setting the content of alicyclic monomer units within the above range, the compatibility between the (meth)acrylic polymer and the tackifying resin can be improved, and the adhesion between the adhesive sheet and the adhered object can be improved more effectively.

[0062] The tackifying resin may further contain alkyl (meth)acrylate units. Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, and other alkyl (meth)acrylates. Preferably, the tackifying resin contains methyl (meth)acrylate. The content of alkyl (meth)acrylate units relative to the total mass of the tackifying resin is preferably 10% by mass or more, more preferably 15% by mass or more. Furthermore, the content of alkyl (meth)acrylate units relative to the total mass of the tackifying resin is preferably 95% by mass or less, more preferably 90% by mass or less. By setting the content of alkyl (meth)acrylate units within the above range, the compatibility between the (meth)acrylate polymer and the tackifying resin can be improved, and the adhesion between the adhesive sheet and the adhered object can be improved more effectively.

[0063] The tackifying resin may contain other monomer units as needed. These other monomers are only required to copolymerize with the aforementioned monomer components; examples include (meth)acrylonitrile, vinyl acetate, vinyl chloride, and ethyl vinyl ether. The content of other monomer units in the tackifying resin is preferably 10% by mass or less, more preferably 5% by mass or less.

[0064] The content of the tackifying resin in the adhesive composition is preferably 1 part by weight or more, more preferably 1.2 parts by weight or more, and even more preferably 1.5 parts by weight or more, relative to 100 parts by weight of the total mass of the (meth)acrylic polymer and the monomers constituting the (meth)acrylic polymer. Furthermore, the content of the tackifying resin in the adhesive composition is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and even more preferably 25 parts by weight or less, relative to 100 parts by weight of the total mass of the (meth)acrylic polymer and the monomers constituting the (meth)acrylic polymer. It should be noted that in the adhesive sheet composed of the adhesive composition, the monomers constituting the (meth)acrylic polymer constitute the (meth)acrylic polymer; therefore, the content of the tackifying resin relative to 100 parts by weight of the (meth)acrylic polymer is preferably within the above-mentioned range. By setting the content of the tackifying resin within the above-mentioned range, the adhesion of the adhesive sheet to the adhered object can be improved, and consequently, the degassing resistance of the adhesive sheet can be improved more effectively.

[0065] Cyclic polymerizable multifunctional monomers / Multifunctional monomers with cyclic structures

[0066] The adhesive composition comprises at least one selected from cyclizable polyfunctional monomers and polyfunctional monomers having a cyclic structure. These polyfunctional monomers are polyfunctional monomers having two or more reactive double bonds within the molecule, preferably having two or more but less than five reactive double bonds, more preferably having two or more but less than four reactive double bonds. Furthermore, the reactive double bonds are preferably free radical polymerizable unsaturated groups. It can be considered that by comprising at least one selected from cyclizable polyfunctional monomers and polyfunctional monomers having a cyclic structure in the adhesive composition, (meth)acrylic acid polymers can be nonlinearly crosslinked, thereby enabling the production of adhesive sheets that combine flexibility and cohesive strength. As a result, adhesive sheets exhibiting excellent adhesion to the adhered objects can be obtained.

[0067] Cyclopolymerizable polyfunctional monomers are polyfunctional monomers that form cyclic structures during polymerization. Preferably, the cyclpolymerizable polyfunctional monomer is a polyfunctional monomer that forms a cyclic ether structure during polymerization. The cyclpolymerizable polyfunctional monomer is preferably a polyfunctional monomer having at least two free radical polymerizable unsaturated groups, for example, having the right-end structure in the following structural formula. As shown in the reaction pathway below, the cyclpolymerizable polyfunctional monomer undergoes free radical polymerization in the presence of a chain transfer agent during polymerization, forming a cyclic structure (cyclic ether structure) in the main chain. The formed cyclic structure (cyclic ether structure) is preferably a 3- to 8-membered ring, more preferably a 5- or 6-membered ring.

[0068]

[0069] In the formula, R represents a hydrogen atom or a substituent, preferably an organic group with 1 to 30 carbon atoms. R is preferably a saturated hydrocarbon group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, tert-pentyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, sec-octyl, tert-octyl, 2-ethylhexyl, octyl, nonyl, decyl, undecyl, lauryl, tridecyl, myristyl, pentadecyl, cetyl, heptadecanyl, stearyl, nonadecanyl, eicosyl, hexadecyl, beeswaxyl, etc., and is particularly preferably methyl or ethyl.

[0070] It should be noted that, in the formula, X is preferably a chain transfer agent. Examples of chain transfer agents include industrially used compounds such as thiol carboxylic acids, thiol carboxylic esters, alkyl thiols, thiol alcohols, aromatic thiols, and thiol isocyanurates, which contain a thiol group.

[0071] Examples of cyclizable polyfunctional monomers include α-allyloxymethacrylate, methyl α-allyloxymethacrylate, ethyl α-allyloxymethacrylate, n-propyl α-allyloxymethacrylate, isopropyl α-allyloxymethacrylate, n-butyl α-allyloxymethacrylate, sec-butyl α-allyloxymethacrylate, tert-butyl α-allyloxymethacrylate, n-pentyl α-allyloxymethacrylate, sec-pentyl α-allyloxymethacrylate, and α-allyloxymethyl methacrylate. The monomers include tert-amyl acrylate, n-hexyl α-allyloxymethacrylate, sec-hexyl α-allyloxymethacrylate, n-heptyl α-allyloxymethacrylate, n-octyl α-allyloxymethacrylate, sec-octyl α-allyloxymethacrylate, tert-octyl α-allyloxymethacrylate, 2-ethylhexyl α-allyloxymethacrylate, octyl α-allyloxymethacrylate, nonyl α-allyloxymethacrylate, decyl α-allyloxymethacrylate, and undecyl α-allyloxymethacrylate. Preferably, the cyclizable polyfunctional monomer is selected from at least one of the group consisting of α-allyloxymethacrylate, methyl α-allyloxymethacrylate, and ethyl α-allyloxymethacrylate, more preferably from at least one of the group consisting of methyl α-allyloxymethacrylate and ethyl α-allyloxymethacrylate. As a cyclizable polymerizable multifunctional monomer, a monomer such as that described in Japanese Patent Application Publication No. 2010-168539 may be used.

[0072] Alternatively, commercially available products can be used as cyclizable, multifunctional monomers. Examples of commercially available products include AOMA manufactured by Nippon Shokubai Co., Ltd.

[0073] On the other hand, a polyfunctional monomer with a cyclic structure is a polyfunctional monomer that already has a cyclic structure before polymerization. The adhesive composition preferably contains a polyfunctional monomer with a cyclic structure.

[0074] The ring structure of a multifunctional monomer with a ring structure is preferably an alicyclic, heterocyclic, or aromatic ring, more preferably an alicyclic or heterocyclic ring. Examples of alicyclic rings include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cycloundecane, cyclododecane, norbornene, norbornadiene, dicyclopentane, tetrahydrofuran, and tetrahydropyran. It should be noted that alicyclic rings can have a spirocyclic structure. Examples of aromatic rings include benzene, naphthalene, and anthracene. When the ring structure of a multifunctional monomer with a ring structure is a heterocyclic ring, examples of heterocyclic rings (including heteroaromatic rings) include pyridine, pyrimidine, purine, furan, benzofuran, pyrrole, thiophene, imidazole, oxazole, ethyleneimine, ethylene oxide, cyclothioethane, 1,3-epoxypropane, and triazole. The heterocycle is preferably a ring containing oxygen or nitrogen atoms, and more preferably a ring containing oxygen atoms.

[0075] The ring structure of a multifunctional monomer with a ring structure is preferably a 5-membered ring or a 6-membered ring.

[0076] Examples of multifunctional monomers with cyclic structures include dioxanediol diacrylate, tricyclodecanediethanol di(meth)acrylate, alkoxy-modified bisphenol A di(meth)acrylate, caprolactone-modified isocyanurate di(meth)acrylate, tris(2-acryloyloxyethyl) isocyanurate, tri-(2-acryloyloxyethyl) isocyanurate, bis-(2-acryloyloxyethyl) isocyanurate, and tri-(2-acryloyloxyethyl) isocyanurate. Among these, multifunctional monomers with cyclic structures are preferably multifunctional acrylic monomers.

[0077] Commercially available products can also be used as multifunctional monomers with cyclic structures. Examples of commercially available products include A-DOG, A-DCP, A-9300, and A-9200YN manufactured by Shin-Nakamura Chemical Co., Ltd., and FA-731A manufactured by Hitachi Chemical Co., Ltd.

[0078] Cyclic polymerizable polyfunctional monomers and / or polyfunctional monomers with cyclic structures form a crosslinked structure with the aforementioned (meth)acrylic acid polymer in the adhesive sheet. It should be noted that the content of the cyclic polymerizable polyfunctional monomers and / or polyfunctional monomers with cyclic structures in the adhesive composition is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, relative to 100 parts by weight of the total mass of the (meth)acrylic acid polymer and the monomers constituting the (meth)acrylic acid polymer. Furthermore, the content of the cyclic polymerizable polyfunctional monomers and / or polyfunctional monomers with cyclic structures in the adhesive composition is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, relative to 100 parts by weight of the total mass of the (meth)acrylic acid polymer and the monomers constituting the (meth)acrylic acid polymer. The adhesive composition may contain both cyclic polymerizable polyfunctional monomers and polyfunctional monomers with cyclic structures; in this case, the total content of the cyclic polymerizable polyfunctional monomers and polyfunctional monomers with cyclic structures is preferably within the above-mentioned range. By setting the content of cyclized polymerizable polyfunctional monomers and / or polyfunctional monomers with cyclic structures within the above range, the adhesion of the adhesive sheet can be improved more effectively.

[0079] <Other multifunctional monomers>

[0080] The adhesive composition may further include, in addition to the aforementioned multifunctional monomers, a multifunctional monomer having two or more reactive double bonds within its molecule. In this case, the multifunctional monomer is a non-cyclic multifunctional monomer (hereinafter, sometimes referred to as a second multifunctional monomer). The second multifunctional monomer preferably has two or more but less than five reactive double bonds, more preferably two or more but less than four.

[0081] Examples of second-multifunctional monomers, such as difunctional monomers, include polyethylene glycol diacrylate, polypropylene diacrylate, alkyl diacrylate, polytetramethylene glycol diacrylate, and polypropylene glycol diacrylate. Examples of monomers with trifunctionality or higher include alkoxylated trimethylolpropane triacrylate, alkoxylated glycerol triacrylate, pentaerythritol acrylate, alkoxylated pentaerythritol acrylate, (alkoxylated) pentaerythritol acrylate, (alkoxylated) bis(trimethylolpropane) acrylate, (alkoxylated) dipentaerythritol acrylate, and (ethoxylated) polyglycerol acrylate.

[0082] As a second multifunctional monomer, commercially available products can be used. Examples of commercially available products include the difunctional monomer A-200 (polyethylene glycol #200 diacrylate) and the trifunctional monomer A-TMPT ((alkoxylated) trimethylolpropane acrylate) manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; and the difunctional monomer M240 (polyethylene glycol diacrylate) and the tetrafunctional monomer M-408 (bis(trimethylolpropane tetraacrylate)) manufactured by Toa Synthetic Co., Ltd.

[0083] The second polyfunctional monomer forms a cross-linked structure with the aforementioned (meth)acrylic acid polymer in the adhesive sheet. It should be noted that the content of the second polyfunctional monomer in the adhesive composition is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, relative to 100 parts by mass of the total mass of the (meth)acrylic acid polymer and the monomers constituting the (meth)acrylic acid polymer. Furthermore, the content of the second polyfunctional monomer in the adhesive composition is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of the total mass of the (meth)acrylic acid polymer and the monomers constituting the (meth)acrylic acid polymer. By setting the content of the second polyfunctional monomer within the above range, the hardness of the adhesive sheet can be improved, and the durability, processability, and adhesion of the adhesive sheet can be improved.

[0084] (Monofunctional monomer)

[0085] Adhesive compositions may contain monofunctional monomers. A monofunctional monomer is a monomer having one reactive double bond within its molecule.

[0086] Examples of monofunctional monomers include isobornyl (meth)acrylate, isostearyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and benzyl (meth)acrylate. Preferably, the monofunctional monomer has 3 or more carbon atoms, more preferably 5 or more, further preferably 7 or more, even more preferably 9 or more, and particularly preferably 10 or more. Furthermore, the monofunctional monomer is preferably a monofunctional monomer with a cyclic structure, more preferably isobornyl (meth)acrylate. Examples of commercially available monofunctional monomers include IBXA and IBXMA manufactured by Osaka Organic Chemicals Co., Ltd.

[0087] The content of the monofunctional monomer in the adhesive composition is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic polymer and the monomers constituting the (meth)acrylic polymer. Furthermore, the content of the monofunctional monomer in the adhesive composition is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer and the monomers constituting the (meth)acrylic polymer. By setting the content of the monofunctional monomer within the above range, the adhesion of the adhesive sheet can be improved more effectively.

[0088] Crosslinking agent

[0089] In addition to the aforementioned multifunctional monomers, the adhesive composition may further include a crosslinking agent. The crosslinking agent may be appropriately selected considering its reactivity with the crosslinking functional groups possessed by (meth)acrylic polymers. It can be selected from known crosslinking agents such as isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, metal chelate compounds, and butylated melamine compounds. Preferably, the crosslinking agent comprises at least one selected from isocyanate compounds, epoxy compounds, and metal chelate compounds.

[0090] Photopolymerization initiators

[0091] The adhesive composition may further include a photopolymerization initiator. The photopolymerization initiator initiates the polymerization of multifunctional monomers by irradiation with active energy rays. Here, "active energy rays" refers to rays containing energy quanta within electromagnetic waves or beams of charged particles, such as ultraviolet light, electron beams, visible light, X-rays, and ion beams. From a general viewpoint, ultraviolet light or electron beams are preferred, with ultraviolet light being particularly preferred.

[0092] There are no particular limitations on photopolymerization initiators, but examples include acetophenone-based photopolymerization initiators such as 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-methylpropanone, and 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methyl-1-propanone; acylphosphine oxide-based photopolymerization initiators such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; intramolecular hydrogen abstraction photopolymerization initiators such as methyl benzoylformate and 4-methylbenzophenone; and oil-soluble polymerization initiators such as oxime ester-based and cationic photopolymerization initiators. The photopolymerization initiator is preferably selected from at least one of the following groups: acetophenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, and oxime ester-based photopolymerization initiators.

[0093] Commercially available acetophenone-based photopolymerization initiators include EsacureOne (oligomeric (2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenylacetone], photoinitiator manufactured by IGM RESINS BV), Omnirad 651 (2,2-dimethoxy-2-phenylacetophenone, manufactured by IGM RESINS BV), Omnirad 184 (1-hydroxycyclohexyl-phenyl ketone, manufactured by IGM RESINS BV), and Omnirad 1173 (2-hydroxy-2-methyl-1-phenylacetone, manufactured by IGM RESINS BV). Commercially available acylphosphine oxide-based photopolymerization initiators include Omnirad 819 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, manufactured by IGM RESINS BV) and Omnirad TPO (2,4,6-trimethylbenzoyl-diphenylphosphine oxide, manufactured by IGM RESINS BV). (e.g., RESINS BV company).

[0094] The content of the photopolymerization initiator in the adhesive composition is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, relative to 100 parts by mass of the total mass of the (meth)acrylic polymer and the monomers constituting the (meth)acrylic polymer. Furthermore, the content of the photopolymerization initiator in the adhesive composition is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of the total mass of the (meth)acrylic polymer and the monomers constituting the (meth)acrylic polymer. By setting the content of the photopolymerization initiator within the above range, the hardness of the adhesive sheet can be improved, and the durability, processability, and adhesion of the adhesive sheet can be improved.

[0095] <Silane Coupling Agent>

[0096] The adhesive composition may further contain a silane coupling agent. By including a silane coupling agent in the adhesive composition, the adhesion between the adhesive sheet formed from the adhesive composition and the adherend can be further improved.

[0097] Examples of silane coupling agents include, for example, mercapto-based silane coupling agents containing mercapto groups, epoxy-based silane coupling agents containing epoxy groups, vinyl-based silane coupling agents containing vinyl groups, and isocyanurate-based silane coupling agents.

[0098] Commercially available products can also be used as silane coupling agents. Examples of commercially available products include KBM-9659, KBM-5103, KBM-502, KBM-503, KBM-402, and KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.

[0099] The content of the silane coupling agent in the adhesive composition is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the total mass of the (meth)acrylic polymer and the monomers constituting the (meth)acrylic polymer. Furthermore, the content of the silane coupling agent in the adhesive composition is preferably 10 parts by mass or less, relative to 100 parts by mass of the total mass of the (meth)acrylic polymer and the monomers constituting the (meth)acrylic polymer. By setting the content of the silane coupling agent within the above range, the adhesion of the adhesive sheet can be improved more effectively.

[0100] Solvent

[0101] The adhesive composition may contain a solvent. In this case, the solvent is used to improve the coating adaptability of the adhesive composition. Examples of solvents include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and diacetone alcohol; ethers such as diethyl ether, diisopropyl ether, dioxane, and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, and cyclohexanone; esters such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, and ethyl butyrate; and polyols and their derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monomethyl ether acetate.

[0102] <Other Ingredients>

[0103] The adhesive composition may contain other components besides those described above, without impairing the effects of the present invention. Examples of other components include those known as adhesive additives. Light stabilizers such as plasticizers, antioxidants, metal corrosion inhibitors, UV absorbers, and hindered amine compounds can be selected as needed. Additionally, dyes and pigments may be added for coloring.

[0104] As plasticizers, for example, non-functional acrylic polymers can be used. Examples of non-functional acrylic polymers include polymers composed solely of acrylic monomer units lacking functional groups other than acrylate groups, polymers containing acrylic monomer units lacking functional groups other than acrylate groups, and non-acrylic monomer units lacking functional groups. Non-functional acrylic polymers do not undergo cross-linking; therefore, they can improve contour following when bonded to substrates without affecting adhesion.

[0105] Examples of antioxidants include phenolic antioxidants, amine antioxidants, lactone antioxidants, phosphorus antioxidants, and sulfur antioxidants. These antioxidants can be used alone or in combination of two or more.

[0106] Benzotriazole resins are preferred examples of metal corrosion inhibitors, considering their compatibility and effectiveness with adhesives.

[0107] Examples of ultraviolet absorbers include benzotriazole compounds, benzophenone compounds, and triazine compounds.

[0108] (Adhesive sheet)

[0109] This invention also relates to adhesive sheets formed by curing the above-described adhesive composition. The adhesive sheet of this invention can be formed by heat drying or by photocuring the above-described adhesive composition. Preferably, the adhesive sheet is formed by photocuring the above-described adhesive composition, and when forming the adhesive sheet of this invention, it is preferable to irradiate the adhesive composition with active energy rays to carry out the curing reaction. Examples of active energy rays include ultraviolet rays, electron rays, visible light, X-rays, and ion rays. From a general viewpoint, ultraviolet rays or electron rays are preferred, and ultraviolet rays are particularly preferred.

[0110] The adhesive sheet of the present invention is preferably an adhesive sheet consisting only of an adhesive layer, or a double-sided adhesive sheet. Examples of double-sided adhesive sheets include single-layer adhesive sheets consisting of adhesive layers, multi-layer adhesive sheets with multiple adhesive layers stacked together, and multi-layer adhesive sheets with other adhesive layers stacked between adhesive layers. It should be noted that the adhesive sheet of the present invention can be a multi-layer adhesive sheet with a support layer stacked between adhesive layers. When the double-sided adhesive sheet has a support layer, a transparent support layer is preferably used. A general thin film used in the optical field, similar to a transparent substrate, can be used as the support layer. This double-sided adhesive sheet also has excellent overall transparency, and therefore, it is suitable for bonding optical components together.

[0111] This invention can relate to an adhesive sheet with release tabs, wherein release tabs are provided on both surfaces of the adhesive sheet. In the case where the adhesive sheet of this invention has release tabs on both surfaces, such as... Figure 1 As shown, the adhesive sheet 10 with release tabs preferably has release tabs 12a and 12b on both surfaces of the adhesive layer 11.

[0112] Examples of release sheets include: release sheet laminates having a release sheet substrate and a release agent layer disposed on one side of the release sheet substrate; or polyolefin films such as polyethylene film and polypropylene film as polar substrates.

[0113] The release liner substrate in the release laminate can be paper or a polymer film. The release agent constituting the release agent layer can be, for example, a general-purpose addition-type or condensation-type silicone release agent or a compound containing a long-chain alkyl group. Highly reactive addition-type silicone release agents are particularly preferred.

[0114] As silicone-based release agents, examples include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicones Co., Ltd., and KS-3600, KS-774, and X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. Furthermore, silicone-based release agents preferably contain silicone resin, which has SiO2 units and (CH3)3SiO2 units. 1 / 2 Unit or CH2=CH(CH3)SiO 1 / 2 Organosilicon compounds of the unit. Specific examples of organosilicon resins include BY24-843, SD-7292, and SHR-1404 manufactured by Toray Dow Corning Silicones Co., Ltd.; and KS-3800 and X92-183 manufactured by Shin-Etsu Chemical Co., Ltd.

[0115] Commercially available products can be used as release-resistant laminates. Examples include the heavy separator film A71 manufactured by Teijin-DuPont Film Co., Ltd., which is a release-treated polyethylene terephthalate film, and the light separator film A38ST manufactured by Teijin-DuPont Film Co., Ltd., which is a release-treated polyethylene terephthalate film.

[0116] The adhesive sheet with release tabs preferably has a pair of release tabs on its two surfaces with different peel forces. That is, to make the release tabs easy to peel off, it is preferable that the release tabs 12a and 12b have different peel forces. If the peel force when peeling from one side is different from that when peeling from the other side, it is easy to peel off the release tab on the side with the higher peel force first. In this case, the peel forces of the release tabs 12a and 12b can be adjusted according to the bonding method and bonding sequence.

[0117] The thickness of the adhesive sheet can be appropriately set according to the application and is not particularly limited, but is preferably 5 to 1000 μm, more preferably 8 to 500 μm, and particularly preferably 10 to 300 μm. By setting the thickness of the adhesive sheet within the above range, the adhesive performance can be maintained and the overflow and stickiness of the adhesive can be suppressed, thereby improving processability. Furthermore, by setting the thickness of the adhesive layer within the above range, it is easy to manufacture double-sided adhesive sheets.

[0118] <Method for manufacturing adhesive sheets>

[0119] The method for manufacturing the adhesive sheet of the present invention preferably includes: a step of coating an adhesive composition onto a release sheet to form a coating film; a step of heating the coating film; or a step of irradiating the coating film with active energy rays. It should be noted that, when the adhesive composition contains a solvent, a heating and drying step is preferably included. In the heating and drying step, the adhesive layer is formed by removing the solvent.

[0120] The coating of the adhesive composition can be carried out using known coating apparatus. Examples of coating apparatus include, for example, blade coaters, air knife coaters, roller coaters, bar coaters, gravure coaters, micro-gravure coaters, bar-blade coaters, lip coaters, die coaters, curtain coaters, etc.

[0121] In the process of heating the coating film, it is preferable to place the coating film under heating conditions for drying. The temperature in the heating process is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 85°C or higher. Furthermore, the temperature in the heating process is preferably 150°C or lower. The processing time in the heating process is preferably 10 seconds or more, more preferably 1 minute or more, and even more preferably 2 minutes or more. Furthermore, the processing time in the heating process is preferably 1 hour or less.

[0122] In the process of irradiating the coating with active energy rays, it is preferable to have a cumulative light intensity of 100–10000 mJ / cm. 2 Irradiation with active energy rays in a manner that is more preferably 500–5000 mJ / cm 2 The coating is irradiated with active energy rays in a manner that allows for two-stage irradiation. For example, the irradiation intensity in the second stage can be increased compared to the first stage. By performing this two-stage irradiation, the molecular weight of the polymer contained in the resulting adhesive sheet can be adjusted, and thermal shrinkage of separators and the like can be suppressed.

[0123] <Uses of Adhesive Sheets>

[0124] The adhesive sheet of the present invention is used to adhere objects, preferably optical components. Examples of optical components include various constituent components in optical products such as touch panels and image display devices. Examples of constituent components of touch panels include, for example, ITO films with an ITO film disposed on a transparent resin film, ITO glass with an ITO film disposed on the surface of a glass plate, transparent conductive films with a conductive polymer coated on a transparent resin film, hard-coated films, and fingerprint-resistant films. Examples of constituent components of image display devices include, for example, anti-reflective films, alignment films, polarizing films, phase difference films, and brightness enhancement films used in liquid crystal display devices. Furthermore, the adhesive sheet of the present invention can be used to adhere modules such as liquid crystal modules and touch panel modules to each other.

[0125] Materials used in these optical components include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate (PMMA), polyethylene naphthalate, cyclic olefin polymers, cellulose triacetate, polyimide, and cellulose acylates. The adhesive is particularly preferably composed of at least one material selected from glass, polycarbonate, and PMMA.

[0126] In addition, to improve the adhesion between these optical components and the adhesive sheet, the surface of the optical components can be treated with corona discharge or plasma.

[0127] (Layered structure)

[0128] This invention relates to a laminate comprising the aforementioned adhesive sheet and an adherend. Here, the adherend is preferably an optical component, and is preferably selected from at least one of glass, polycarbonate, and PMMA. The laminate of this invention is preferably a laminate comprising the aforementioned adhesive sheet and a polycarbonate sheet or a PMMA sheet. The adhesive sheet of this invention is particularly capable of providing excellent adhesion to polycarbonate sheets.

[0129] Example

[0130] The following examples and comparative examples illustrate the features of the present invention in more detail. The materials, amounts, proportions, processing contents, processing steps, etc., shown in the following examples can be appropriately modified without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited by the specific examples shown below.

[0131] (Example 1)

[0132] <Manufacturing Method of Acrylic Polymer A>

[0133] 620g of 2-ethylhexyl acrylate, 290g of 4-hydroxybutyl acrylate, 90g of cyclohexyl methacrylate, and 0.1g of n-dodecyl mercaptan were added to a 2L flask equipped with a stirrer, nitrogen inlet tube, condenser, and thermometer. The mixture was purged with nitrogen at a flow rate of 300ml / min for 60 minutes, then the nitrogen flow rate was reduced to 100ml / min, and the mixture was heated to 65°C in a water bath. 0.15g of AIBN was added, and the reaction was allowed to proceed for 30 minutes while controlling the exothermic reaction, followed by cooling to room temperature. Additional monomers were added to the flask in the same monomer ratio as described above, adjusting the solids concentration to 20%. Following these steps, a slurry A containing an acrylic polymer A with a solids concentration of 20% by mass and a weight-average molecular weight of approximately 900,000 was obtained.

[0134] <Manufacturing method of tackifying resin A>

[0135] 250g of methyl methacrylate, 250g of isobornyl methacrylate, 20g of n-dodecyl mercaptan, 500g of ethyl acetate, and 200g of methyl ethyl ketone were added to a 2L flask equipped with a stirrer, nitrogen inlet tube, condenser, and thermometer. Nitrogen was purged at a flow rate of 300ml / min for 60 minutes, then the nitrogen flow rate was reduced to 100ml / min. The mixture was heated to 70°C in a water bath and then heating was stopped. 2g of AIBN was added, and the reaction was allowed to proceed for 3 hours while controlling the exothermic reaction. Then, 3g of AIBN was added, and the reaction was allowed to continue for 4 hours before cooling to 30°C. Following this procedure, a tackifying resin a with a weight-average molecular weight of 6,000 and a glass transition temperature of 95°C was obtained.

[0136] <Manufacturing of Adhesive Sheets>

[0137] For tackifying resin a, it was dried at 100°C for 5 hours to remove the solvent. To 100g of slurry A, 5g of tackifying resin a (solvent removed), 3g of isobornyl acrylate, 1g of cyclized polyfunctional monomer (AOMA, manufactured by Nippon Shokubai Co., Ltd.), 0.3g of polyfunctional monomer (NK ESTER A-200, manufactured by Shin-Nakamura Chemical Co., Ltd.), 0.1g of silane coupling agent (KBM-9659, manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.3g of photopolymerization initiator (Esacure One, manufactured by IGM Resins BV Co., Ltd.) were added, and the mixture was stirred to remove bubbles, yielding an adhesive composition. The adhesive composition was coated to a thickness of 175μm onto a 100μm thick polyester film coated with a silicone release agent. After lamination with a 75μm thick polyester film coated with a silicone release agent, the mixture was subjected to an illuminance of 5mW / cm². 2 The cumulative illuminance is 900 mJ / cm². 2 The chemical lamp was irradiated in a manner that resulted in an illuminance of 200 mW / cm². 2 The cumulative illuminance is 2000 mJ / cm². 2 The adhesive sheet is obtained by irradiating a high-pressure mercury lamp in a certain way.

[0138] (Example 2)

[0139] In the <Manufacturing of Adhesive Sheet>, the amount of cyclized polymerizable multifunctional monomer (manufactured by Nippon Shokubai Co., Ltd., AOMA) added was changed to 0.2g, and the amount of multifunctional monomer (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., NK ESTER A-200) added was changed to 0.2g. Otherwise, the adhesive sheet was made in the same manner as in Example 1.

[0140] (Example 3)

[0141] In the manufacture of the adhesive sheet, instead of the cyclized polymerizable polyfunctional monomer (manufactured by Nippon Shokubai Co., Ltd., AOMA), 0.15g of dioxanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-DOG) was added as a polyfunctional monomer with a cyclic structure. The amount of the polyfunctional monomer (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ESTER A-200) was changed to 0.2g. Otherwise, the adhesive sheet was manufactured in the same manner as in Example 1.

[0142] (Example 4)

[0143] In the manufacture of the adhesive sheet, instead of the cyclized polymerizable polyfunctional monomer (AOMA manufactured by Nippon Shokubai Co., Ltd.), 0.1 g of tricyclodecanediethanol diacrylate (A-DCP manufactured by Shin-Nakamura Chemical Co., Ltd.) was added as a polyfunctional monomer with a cyclic structure. The amount of the polyfunctional monomer (NK ESTER A-200 manufactured by Shin-Nakamura Chemical Co., Ltd.) was changed to 0.2 g. Otherwise, the adhesive sheet was manufactured in the same manner as in Example 1.

[0144] (Example 5)

[0145] <Manufacturing Method of Acrylic Polymer B>

[0146] 670g of 2-ethylhexyl acrylate, 240g of 4-hydroxybutyl acrylate, 90g of cyclohexyl methacrylate, and 0.1g of n-dodecyl mercaptan were added to a 2L flask equipped with a stirrer, nitrogen inlet tube, condenser, and thermometer. The mixture was purged with nitrogen at a flow rate of 300ml / min for 60 minutes, then the nitrogen flow rate was reduced to 100ml / min, and the mixture was heated to 65°C in a water bath. 0.15g of AIBN was added, and the reaction was allowed to proceed for 30 minutes while controlling the exothermic reaction, followed by cooling to room temperature. Additional monomers were added to the flask in the same monomer ratio as described above, adjusting the solids concentration to 20%. Following these steps, a slurry B containing an acrylic polymer B with a solids concentration of 20% by mass and a weight-average molecular weight of approximately 900,000 was obtained.

[0147] <Manufacturing of Adhesive Sheets>

[0148] The tackifying resin a, prepared using the same method as in Example 1, was dried at 100°C for 5 hours to remove the solvent. 5g of the solvent-removed tackifying resin a, 3g of isobornyl methacrylate, 0.2g of tricyclodecanedimethyl diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-DCP), 0.2g of a multifunctional monomer with a cyclic structure (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., NK ESTER A-200), 0.1g of a silane coupling agent (manufactured by Shin-Etsu Chemical Industry Co., Ltd., KBM-9659), and 0.3g of a photopolymerization initiator (manufactured by IGM Resins BV, Esacure One) were stirred and degassed to obtain the adhesive composition. The adhesive composition was coated to a thickness of 175 μm onto a 100 μm thick polyester film coated with a silicone release agent. After lamination with a 75 μm thick polyester film coated with a silicone release agent, the lamination was performed at an illuminance of 5 mW / cm². 2 The cumulative illuminance is 900 mJ / cm². 2 The chemical lamp was irradiated in a manner that resulted in an illuminance of 200 mW / cm². 2 The cumulative illuminance is 2000 mJ / cm². 2 The adhesive sheet is obtained by irradiating a high-pressure mercury lamp in a certain way.

[0149] (Example 6)

[0150] <Manufacturing Method of Acrylic Polymer C>

[0151] 620g of butyl acrylate, 290g of 4-hydroxybutyl acrylate, 90g of cyclohexyl acrylate, and 0.1g of n-dodecyl mercaptan were added to a 2L flask equipped with a stirrer, nitrogen inlet tube, condenser, and thermometer. Nitrogen was purged at a flow rate of 300ml / min for 60 minutes, then the flow rate was reduced to 100ml / min, and the mixture was heated to 65°C in a water bath. 0.15g of AIBN was added, and the reaction was allowed to proceed for 30 minutes while controlling the exothermic reaction, followed by cooling to room temperature. Additional monomers were added to the flask at the aforementioned monomer ratios, adjusting the solids concentration to 20%. Following these steps, a slurry C containing an acrylic polymer C with a solids concentration of 20% by mass and a weight-average molecular weight of approximately 900,000 was obtained.

[0152] <Manufacturing of Adhesive Sheets>

[0153] The tackifying resin a, prepared using the same method as in Example 1, was dried at 100°C for 5 hours to remove the solvent. To 100g of slurry C, 5g of the solvent-removed tackifying resin a, 3g of isobornyl methacrylate, 1g of a cyclized polyfunctional monomer (AOMA, manufactured by Nippon Shokubai Co., Ltd.), 0.3g of a polyfunctional monomer (NK ESTER A-200, manufactured by Shin-Nakamura Chemical Co., Ltd.), 0.1g of a silane coupling agent (KBM-9659, manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.3g of a photopolymerization initiator (Esacure One, manufactured by IGM Resins B.V.) were added, and the mixture was stirred to remove bubbles, yielding an adhesive composition. The adhesive composition was coated to a thickness of 175μm onto a 100μm thick polyester film coated with a silicone release agent. After lamination with a 75μm thick polyester film coated with a silicone release agent, the mixture was subjected to an illuminance of 5mW / cm². 2 The cumulative illuminance is 900 mJ / cm². 2 The chemical lamp was irradiated in a manner that resulted in an illuminance of 200 mW / cm². 2 The cumulative illuminance is 2000 mJ / cm². 2 The adhesive sheet is obtained by irradiating a high-pressure mercury lamp in a certain way.

[0154] (Comparative Example 1)

[0155] In the manufacture of the adhesive sheet, the cyclized polymerizable multifunctional monomer (manufactured by Nippon Shokubai Co., Ltd., AOMA) was not added, and the amount of multifunctional monomer (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., NK ESTER A-200) was changed to 0.5g. Otherwise, the adhesive sheet was manufactured in the same manner as in Example 1.

[0156] (Comparative Example 2)

[0157] In the manufacture of the adhesive sheet, instead of the cyclizable polyfunctional monomer (AOMA manufactured by Nippon Shokubai Co., Ltd.), 0.15g of 1,6-hexanediol diacrylate (A-HD-N manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) was added as the polyfunctional monomer, and the amount of the polyfunctional monomer (NK ESTER A-200 manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) was changed to 0.2g. Otherwise, the adhesive sheet was manufactured in the same manner as in Example 1.

[0158] (Comparative Example 3)

[0159] In the manufacture of the adhesive sheet, instead of the cyclized polymerizable multifunctional monomer (manufactured by Nippon Shokubai Co., Ltd., AOMA), 0.2 g of 1,10-decanediol diacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., A-DOD-N) was added as the multifunctional monomer, and the amount of multifunctional monomer (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., NK ESTER A-200) was changed to 0.2 g. Otherwise, the adhesive sheet was manufactured in the same manner as in Example 1.

[0160] (Comparative Example 4)

[0161] In the manufacture of the adhesive sheet, no cyclized polymerizable multifunctional monomer (manufactured by Nippon Shokubai Co., Ltd., AOMA) and no multifunctional monomer (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ESTER A-200) were added. Otherwise, the adhesive sheet was manufactured in the same manner as in Example 1.

[0162] (Comparative Example 5)

[0163] <Manufacturing Method of Acrylic Polymer D>

[0164] 500g of 2-ethylhexyl acrylate, 290g of 4-hydroxybutyl acrylate, 210g of cyclohexyl methacrylate, and 0.1g of n-dodecyl mercaptan were added to a 2L flask equipped with a stirrer, nitrogen inlet tube, condenser, and thermometer. The mixture was purged with nitrogen at a flow rate of 300ml / min for 60 minutes, then the nitrogen flow rate was reduced to 100ml / min, and the mixture was heated to 65°C in a water bath. 0.15g of AIBN was added, and the reaction was allowed to proceed for 30 minutes while controlling the exothermic reaction, followed by cooling to room temperature. Additional monomers were added to the flask at the aforementioned monomer ratios, adjusting the solids concentration to 20%. Following these steps, a slurry D containing an acrylic polymer D with a solids concentration of 20% by mass and a weight-average molecular weight of approximately 900,000 was obtained.

[0165] <Manufacturing of Adhesive Sheets>

[0166] Add 3g of isobornyl methacrylate, 0.35g of a multifunctional monomer (NK ESTER A-200, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), and 0.3g of a photopolymerization initiator (Esacure One, manufactured by IGM Resins BV Co., Ltd.) to 100g of slurry D, and stir to remove bubbles to obtain an adhesive composition. Coat the adhesive composition to a thickness of 175μm onto a 100μm thick polyester film coated with a silicone release agent. Then, laminate the mixture using a 75μm thick polyester film coated with a silicone release agent. The lamination is then performed at an illuminance of 5mW / cm². 2 The cumulative illuminance is 900 mJ / cm². 2 The chemical lamp was irradiated in a manner that resulted in an illuminance of 200 mW / cm². 2The cumulative illuminance is 2000 mJ / cm². 2 The adhesive sheet is obtained by irradiating a high-pressure mercury lamp in a certain way.

[0167] (Comparative Example 6)

[0168] <Manufacturing Method of Acrylic Polymer E>

[0169] 760g of butyl acrylate, 150g of 4-hydroxybutyl acrylate, 90g of cyclohexyl methacrylate, and 0.1g of n-dodecyl mercaptan were added to a 2L flask equipped with a stirrer, nitrogen inlet tube, condenser, and thermometer. The mixture was purged with nitrogen at a flow rate of 300ml / min for 60 minutes, then the nitrogen flow rate was reduced to 100ml / min, and the mixture was heated to 65°C in a water bath. 0.15g of AIBN was added, and the reaction was allowed to proceed for 30 minutes while controlling the exothermic reaction, followed by cooling to room temperature. Additional monomers were added to the flask in the same monomer ratio as described above, adjusting the solids concentration to 20%. Following these steps, a slurry E containing an acrylic polymer E with a solids concentration of 20% by mass and a weight-average molecular weight of approximately 900,000 was obtained.

[0170] <Manufacturing of Adhesive Sheets>

[0171] In the manufacture of the adhesive sheet, acrylic polymer E is used, and the adhesive sheet is otherwise manufactured in the same manner as in Example 1.

[0172] (Comparative Example 7)

[0173] <Manufacturing Method of Acrylic Polymer F>

[0174] 710g of 2-ethylhexyl acrylate, 290g of 4-hydroxybutyl acrylate, and 0.1g of n-dodecyl mercaptan were added to a 2L flask equipped with a stirrer, nitrogen inlet tube, condenser, and thermometer. Nitrogen was purged at a flow rate of 300ml / min for 60 minutes, then the flow rate was reduced to 100ml / min, and the mixture was heated to 65°C in a water bath. 0.15g of AIBN was added, and the reaction was allowed to proceed for 30 minutes while controlling the exothermic reaction, followed by cooling to room temperature. Additional monomers were added to the flask in the same monomer ratio as described above, adjusting the solids concentration to 20%. Following these steps, a slurry F containing an acrylic polymer F with a solids concentration of 20% by mass and a weight-average molecular weight of approximately 900,000 was obtained.

[0175] <Manufacturing of Adhesive Sheets>

[0176] In the manufacture of the adhesive sheet, acrylic polymer F was used, and the adhesive sheet was otherwise manufactured in the same manner as in Example 1.

[0177] (Comparative Example 8)

[0178] <Manufacturing Method of Acrylic Polymer G>

[0179] 520g of 2-ethylhexyl acrylate, 290g of 4-hydroxybutyl acrylate, 90g of cyclohexyl methacrylate, 100g of N-vinyl-2-pyrrolidone, and 0.1g of n-dodecyl mercaptan were added to a 2L flask equipped with a stirrer, nitrogen inlet tube, condenser, and thermometer. The mixture was purged with nitrogen at a flow rate of 300ml / min for 60 minutes, then the nitrogen flow rate was reduced to 100ml / min, and the mixture was heated to 65°C in a water bath. 0.15g of AIBN was added, and the reaction was allowed to proceed for 30 minutes while controlling the exothermic reaction, followed by cooling to room temperature. Additional monomers were added to the flask in the same monomer ratio as described above, adjusting the solids concentration to 20%. Following these steps, a slurry G containing an acrylic polymer G with a solids concentration of 20% by mass and a weight-average molecular weight of approximately 900,000 was obtained.

[0180] <Manufacturing of Adhesive Sheets>

[0181] In the manufacture of the adhesive sheet, acrylic polymer G was used, and the adhesive sheet was otherwise manufactured in the same manner as in Example 1.

[0182] (Comparative Example 9)

[0183] <Manufacturing Method of Acrylic Polymer H>

[0184] 520g of 2-ethylhexyl acrylate, 290g of 4-hydroxybutyl acrylate, 90g of cyclohexyl methacrylate, 100g of dimethacrylamide, and 0.1g of n-dodecyl mercaptan were added to a 2L flask equipped with a stirrer, nitrogen inlet tube, condenser, and thermometer. The mixture was purged with nitrogen at a flow rate of 300ml / min for 60 minutes, then the nitrogen flow rate was reduced to 100ml / min, and the mixture was heated to 65°C in a water bath. 0.15g of AIBN was added, and the reaction was allowed to proceed for 30 minutes while controlling the exothermic reaction, followed by cooling to room temperature. Additional monomers were added to the flask in the same monomer ratio as described above, adjusting the solids concentration to 20%. Following these steps, a slurry H containing an acrylic polymer H with a solids concentration of 20% by mass and a weight-average molecular weight of approximately 900,000 was obtained.

[0185] <Manufacturing of Adhesive Sheets>

[0186] In the manufacture of the adhesive sheet, acrylic polymer H was used, and the adhesive sheet was otherwise manufactured in the same manner as in Example 1.

[0187] (Measurement and Evaluation)

[0188] (Calculation of glass transition temperature of (meth)acrylic acid polymers)

[0189] The glass transition temperature of acrylic polymers is determined using the following FOX formula.

[0190] 1 / Tgp=W1 / Tg1+W2 / Tg2+···+Wn / Tgn

[0191] Tgp is the glass transition temperature of the acrylic polymer, Wn is the weight fraction of each monomer, and Tgn is the glass transition temperature when each monomer is made into a homopolymer.

[0192] (Determination of the glass transition temperature of tackifying resins)

[0193] In the determination of the glass transition temperature of the tackifying resin, a DSC6200 instrument manufactured by Seiko Instruments Inc. was used. A reference of 10 mg of alumina was used. Approximately 10 mg of solvent removal agent for the tackifying resin was added to an aluminum sample container with a diameter of 5 mm. Under nitrogen flow rate of 50 ml / min, the temperature was increased from 0 °C to 150 °C at a rate of 10 °C / min. The inflection point at which the specific heat changes was recorded was taken as the glass transition temperature of the tackifying resin.

[0194] (High-Temperature Constant Load Measurement)

[0195] The resulting adhesive sheet was adhered to a 100μm thick, easily bondable polyester film (A4300, manufactured by Toyobo Co., Ltd.), and cut to a width of 25mm and a length of 50mm for the adhesive portion. Next, it was adhered to a 1mm thick polycarbonate sheet (Taijin Co., Ltd., Panlite 1151) or a 1.1mm thick float glass sheet (Hiraoka Glass Industry Co., Ltd.), and then pressed back and forth twice using a 2kg roller. Afterward, it was treated in an autoclave at 30°C and 0.5MPa for 30 minutes, and then allowed to stand at atmospheric pressure and room temperature for 1 day to obtain the laminate for evaluation.

[0196] After the evaluation laminate was placed in a constant temperature and humidity chamber at 95°C for 30 minutes, it was placed on a table with the polycarbonate sheet or float glass side as the top surface. Next, a 100g weight was hung on the end of the polyester film, and the peel distance (the peel distance between the polycarbonate sheet or float glass and the adhesive sheet) was measured after 30 minutes. The evaluation was conducted according to the following criteria.

[0197] <High-temperature constant load (95℃), adherend: polycarbonate sheet>

[0198] A: The peeling distance is less than 15mm after 30 minutes.

[0199] B: The peeling distance after 30 minutes is more than 15mm and less than 20mm.

[0200] C: The peeling distance after 30 minutes is more than 20mm.

[0201] <High-temperature constant load (95℃), substrate: glass>

[0202] A: The peeling distance is less than 5mm after 30 minutes.

[0203] B: The peeling distance after 30 minutes is more than 5mm and less than 10mm.

[0204] C: The peeling distance after 30 minutes is more than 10mm.

[0205] (Determination of constant damp-heat load)

[0206] The evaluation laminate obtained by the above method was placed in a constant temperature and humidity chamber at 85°C and 85% relative humidity for 60 minutes, and then placed on a table with the polycarbonate sheet or float glass side as the top surface. Next, a 100g weight was hung on the end of the polyester film, and the peel distance (the peel distance between the polycarbonate sheet or float glass and the adhesive sheet) was measured after 30 minutes. The evaluation was carried out according to the following criteria.

[0207] <Constant damp heat load (85°C, 85%), Adhesive: Polycarbonate sheet>

[0208] A: The peeling distance is less than 15mm after 30 minutes.

[0209] B: The peeling distance after 30 minutes is more than 15mm and less than 20mm.

[0210] C: The peeling distance after 30 minutes is more than 20mm.

[0211] <Constant damp-heat load (85°C, 85%), substrate: glass>

[0212] A: The peeling distance is less than 10mm after 30 minutes.

[0213] B: The peeling distance after 30 minutes is more than 10mm.

[0214] C: Fall within 30 minutes

[0215] (Degassing resistance)

[0216] A 55mm wide, 80mm long, and 1mm thick polycarbonate sheet (Teijin Panlite 1151) was glued to one side of the resulting adhesive sheet, and a 52mm wide, 76mm long, and 1mm thick glass sheet (Matsunami) was glued to the other side. The sheet was then treated in an autoclave at 30°C and 0.5MPa for 30 minutes, followed by standing at atmospheric pressure and room temperature for one day. The resulting evaluation laminate was then placed in a 95°C dryer and removed after 6 hours to evaluate for the formation of bubbles and peeling.

[0217] A: No bubbles and no peeling

[0218] C: Bubbles or peeling

[0219] (Light resistance (weather resistance))

[0220] After bonding a 52mm wide, 76mm long, and 1mm thick glass sheet (Matsunami) to both sides of the resulting adhesive sheet, it was treated in an autoclave at 30°C and 0.5MPa for 30 minutes, followed by standing at atmospheric pressure and room temperature for 1 day. Next, the resulting evaluation laminate was placed in a Super XenonWeather Meter SX75 (Suga Test Instruments) at 50% relative humidity, a black panel temperature of 63°C, and an illuminance of 180W / cm². 2 Under the specified conditions, the evaluation laminate was irradiated with light (300–400 nm) for 300 hours. The colorimetry (b* value) of the evaluation laminate was measured using a Coloeer Cute i colorimeter manufactured by Suga Test Instruments, and the evaluation was conducted according to the following criteria.

[0221] A: Compared to the initial b* value, the increase in b* value after light exposure is less than 1.0.

[0222] C: The increase in b* value after light irradiation is greater than 1.0 compared to the pre-evaluation b* value.

[0223] [Table 1]

[0224]

[0225] 2EHA: 2-Ethylhexyl acrylate

[0226] BA: Butyl acrylate

[0227] 4HBA: 4-Hydroxybutyl acrylate

[0228] CHMA: Cyclohexyl methacrylate

[0229] CHA: Cyclohexyl acrylate

[0230] NVP: N-vinyl-2-pyrrolidone

[0231] DMAA: Dimethylacrylamide

[0232] MMA / IBXMA: Methyl methacrylate / isobornyl methacrylate.

[0233] IBXA: Isoborneol Acrylate

[0234] IBXMA: Isoborneol Methacrylate

[0235] Compared to the comparative example, the examples exhibit superior adhesion under high-temperature conditions and / or adhesion under high-temperature and high-humidity conditions. Furthermore, the adhesive sheets obtained in the examples also demonstrate good resistance to degassing and light (weather resistance).

Claims

1. An adhesive composition comprising: (Meth)acrylic polymers, comprising (meth)acrylic monomer units having hydroxyl groups and (meth)acrylic monomer units having ring structures; and Cyclopolymerizable multifunctional monomers The glass transition temperature of the (meth)acrylic acid polymer is below 0°C. The content of the hydroxyl-containing (meth)acrylic monomer units in the (meth)acrylic polymer is 20% by mass or more relative to the total mass of the (meth)acrylic polymer. The content of the cyclic (meth)acrylic monomer units in the (meth)acrylic polymer is 1% by mass or more relative to the total mass of the (meth)acrylic polymer. The content of nitrogen-containing monomer units in the (meth)acrylic polymer is less than 0.1% by mass.

2. The adhesive composition according to claim 1, wherein, The cyclic (meth)acrylic acid monomer unit is a cyclic (meth)acrylic acid monomer unit.

3. The adhesive composition according to claim 1, further comprising a resin having a glass transition temperature of 20°C or higher.

4. The adhesive composition according to claim 1, further comprising a multifunctional monomer that does not have a cyclic structure and has not undergone cyclization.

5. The adhesive composition according to claim 1, further comprising a monofunctional monomer having a cyclic structure.

6. The adhesive composition according to claim 1, further comprising a silane coupling agent.

7. The adhesive composition according to claim 1, further comprising a photopolymerization initiator.

8. An adhesive sheet formed from the adhesive composition according to any one of claims 1 to 7.

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