JP7181601B2 - Photocurable adhesive composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photocurable adhesive composition that can be used for laminating an optical display or a touch sensor, and a laminate laminated using the same, particularly an optical display.

A touch panel is an electronic component that is widely used in digital information equipment such as mobile phones, ATMs, vending machines, etc., because it can bring about intuitive, simple and versatile operability, miniaturization of the entire device, and the like. The operating principle of a touch panel is to detect electrical changes in the position where the panel is touched, but currently, capacitive devices detect changes in capacitance that occur when a finger touches the panel. is often used.

Conventionally, capacitive touch sensors were externally attached to liquid crystal displays, but in recent years, on-cell or in-cell structures have been adopted in order to reduce the weight and thickness of the entire device. In particular, an in-cell structure in which a function as a touch panel is provided in a thin film transistor has attracted attention and has been put to practical use.

An in-cell touch sensor structure is provided inside the touch panel, for example, inside a thin film transistor. Therefore, the distance between the touch sensor and the front panel is inevitably larger than that of a touch panel provided with an external touch sensor, and the sensitivity of the touch sensor tends to be low. In the in-cell touch panel, it is necessary to increase the dielectric constant of the entire touch panel in order to improve the detection sensitivity. As a method for increasing the dielectric constant of the touch panel, an attempt has been made to increase the dielectric constant of the resin filling the space between the touch sensor and the front panel (Patent Document 1).

It is desirable that the resin filling between the touch sensor and the front panel is liquid for ease of operation. On the other hand, the glass of liquid crystal panels is becoming thinner due to the need for thinner and lighter display devices. Here, when the liquid resin is cured, the glass of the liquid crystal panel may be broken or deformed due to curing shrinkage stress at that time. Since this causes poor display, it is necessary to reduce the curing shrinkage rate and elastic modulus of the liquid resin (Patent Document 2). In addition, in the technology using liquid resin, the liquid resin is applied so as to cover the display part of the liquid crystal panel for adhesion, so the liquid resin used must be an optically transparent resin (OCR). It is required not to cause coloring or discoloration after a heat resistance test and strength reduction after a moisture resistance test (Patent Document 3). Moreover, the liquid resin is preferably of a type that is cured by light such as ultraviolet rays in order to prevent shrinkage due to heat curing and to uniformly cure the entire resin.

JP 2016-50239 A WO2010/027041 Pamphlet JP 2012-046658 A

When the OCR is used in the touch panel, the OCR is filled so as to cover the liquid crystal display. For this reason, the OCR is required to have a high dielectric constant, high transparency, and a low shrinkage rate in order to maintain the function of the touch sensor. Furthermore, there is a demand for OCR with various functions, such as being required to have properties as an adhesive because it is also used as an adhesive. However, according to the present inventors, in the composition described in Patent Document 1, the hydroxyl group contributes to the dielectric constant, but the weight ratio of the monomer component having the hydroxyl group is high, so the other components It was not possible to sufficiently ensure compatibility with, and the physical properties originally required such as suppression of curing shrinkage were insufficient.
Accordingly, an object of the present invention is to provide a photocurable adhesive composition having a high relative dielectric constant while having the properties required for an adhesive for touch panels, such as adhesiveness and transparency.

The present inventors have completed the present invention by discovering that the above-mentioned problems can be achieved by adding a glycol ether or glycol ester having no (meth)acryloyl group to a photocurable adhesive composition. did.

The present invention is specified by the following matters.
That is, the first invention is
(A) (meth)acrylate oligomer,
(B) a monofunctional (meth)acrylate monomer,
A photocurable adhesive composition comprising (C) a glycol ether or glycol ester having no (meth)acryloyl group, and (D) a photoreaction initiator.
In a second invention, the component (A) is one or more selected from the group consisting of polyurethane (meth)acrylate oligomers and (meth)acryloyl group-containing (meth)acrylic copolymers. An adhesive composition.
A third invention is a photocurable adhesive composition, wherein the component (C) is a glycol monoether having no (meth)acryloyl group.
In a fourth invention, the component (C) is isobutyl glycol, isopropyl glycol, isobutyl diglycol, isopropyl diglycol, butyl propylene glycol, butyl propylene diglycol, 2-ethylhexyl glycol, 2-ethylhexyl diglycol, propyl propylene glycol. , propyl propylene diglycol, benzyl glycol and benzyl diglycol.
A fifth invention is a laminate laminated with the photocurable adhesive composition.
A sixth aspect of the invention is the laminate, which is an optical display.

According to the present invention, there is provided a photocurable adhesive composition that satisfies the properties required for adhesives, satisfies OCR properties, can suppress curing shrinkage, and has a high dielectric constant. .

The photocurable adhesive composition of the present invention is described in detail below. Here, the "hydrocarbon group" in the present specification will be explained. A hydrocarbon group is a structure composed of carbon and hydrogen, and is expressed as a monovalent hydrocarbon group, a divalent hydrocarbon group, or the like depending on how many bonds it has. Hydrocarbon groups are divided into chain hydrocarbon groups in which carbon atoms are linked in a chain and cyclic hydrocarbon groups in which carbon atoms form a ring. Including what you have. The cyclic hydrocarbon group is classified into an aromatic ring in which the ring exhibits aromaticity and an alicyclic ring in which the ring does not have aromaticity. Further, when the hydrocarbon group contains an element that produces an optical isomer such as an asymmetric carbon atom or a chirality axis, the group includes each optical isomer, mixture thereof, and racemate.

"Alkyl group" means a linear or branched monovalent hydrocarbon group. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, lauryl, and the like. When specifying the number of carbon atoms in an alkyl group, the range of the number of carbon atoms constituting the alkyl group is modified before the word "alkyl", such as "C _1-6 alkyl". In the case of “C _1-6 alkyl”, the number of carbon atoms ranges from 1 to 6.
The “alkylene group” means a linear or branched divalent hydrocarbon group, that is, a structure in which one hydrogen atom of an alkyl group is replaced with a bond. The position to replace the binder is arbitrary and is not particularly limited. When describing the name of an alkylene group, the suffix of an alkyl group is replaced with "-ene". That is, examples of alkylene groups include methylene, ethylene, propylene, n-butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, and the like. If the number of carbon atoms is 2 or more, the position of the bond may be 2 or more, but unless otherwise specified, both ends of the alkylene group (both ends of the longest carbon chain if there is a branch) are bonds. means a group that is When there is no bond at the terminal, the carbon number assigned according to the nomenclature of organic compounds is indicated, and it means that there is a bond at that position.

An "alkenyl group" means a group in which at least one carbon-carbon single bond of an alkyl group is a carbon-carbon double bond. The position of the carbon-carbon double bond is arbitrary and not particularly limited. Examples of alkenyl groups include ethenyl, 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 1-heptenyl, 1-octenyl, 1-nonenyl, and the like. When the number of carbon atoms is 3 or more and the position of the double bond is considered to be plural, the smaller one of the carbon numbers at which the double bond is present is indicated as a prefix according to the nomenclature of organic compounds. When specifying the number of carbon atoms, the notation for a divalent group conforms to that for an alkyl group. An "alkynyl group" means a group in which at least one carbon-carbon single bond of an alkyl group is a carbon-carbon triple bond, and the notation method conforms to that of an alkenyl group. Examples of alkynyl groups include ethynyl, 1-propynyl, 1-butynyl, 1-pentynyl, 1-hexynyl, 1-heptynyl, 1-octynyl, and the like.

A “cycloalkyl group” means a monovalent hydrocarbon group in which a carbon chain forms a ring and one of the carbon atoms constituting the ring has a bond. The ring may have a structure in which two non-adjacent carbon atoms among the carbon atoms constituting the ring are bridged directly or via an alkylene group. Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, norbornyl, adamantyl, dicyclopentanyl, and the like. When specifying the number of carbon atoms, the notation for a divalent group conforms to that for an alkyl group.

“Aryl group” means a monovalent hydrocarbon group having one or more rings having aromaticity and having a bond at one of the carbon atoms constituting the ring having aromaticity. . The ring may have a structure in which two or more rings are condensed. Examples of aryl groups include phenyl, naphthyl, azulenyl, anthracenyl, and the like. When specifying the number of carbon atoms, the notation for a divalent group conforms to that for an alkyl group.

[(A) (meth) acrylate oligomer]
The photocurable adhesive composition of the present invention contains a (meth)acrylate oligomer (hereinafter sometimes simply referred to as "component (A)"). Since the (meth)acrylate oligomer is cured by light (ultraviolet rays), it plays a role as a base in the photocurable adhesive composition. Molecules with a wide range of structures can be used for the monomer units constituting the oligomer as long as they have acrylic or methacrylic groups. Preferably, the photocurable adhesive composition has a polyurethane (meth)acrylate oligomer, a polyisoprene (meth)acrylate oligomer, a polybutadiene (meth)acrylate oligomer, or a (meth)acryloyl group as the (meth)acrylate oligomer. ) containing one or more (meth)acrylate oligomers selected from the group consisting of acrylic copolymers; More preferably, it contains one or more selected from the group consisting of a polyurethane (meth)acrylate oligomer and a (meth)acrylic copolymer having a (meth)acryloyl group. (Meth)acrylate oligomers including those exemplified above can be used in combination. The (meth)acrylate oligomer preferably has an acrylic equivalent of 200 g/mol or more from the viewpoint that the curing shrinkage of the adhesive composition can be further reduced. "Acrylic equivalent" as used herein refers to the molecular weight per acrylic or methacrylic group.

Specific examples of the (meth)acrylate oligomer are described below. Polyurethane (meth)acrylate oligomers, also called (meth)acrylic-modified polyurethanes, preferably have a molecular weight of 1,000 to 100,000, more preferably 1,000 to 50,000. The structure of the polyurethane is not particularly limited as long as it is modified with (meth)acrylic groups. For example, polyurethane (meth)acrylate oligomers can be obtained from polyurethanes having skeletons such as polyethers and polycarbonates. As the polyurethane (meth)acrylate oligomer, polyether urethane (meth) acrylate, polycarbonate urethane (meth) acrylate, polyester urethane (meth) acrylate, and the like are more preferable from the viewpoint of compatibility with the compounds described below. Commercially available products include, for example, "UN-9200A" (polycarbonate urethane (meth)acrylate manufactured by Negami Kogyo Co., Ltd.) and "UA-10000B" (polyether urethane (meth)acrylate manufactured by KSM).

Polyisoprene (meth)acrylate oligomer, also called (meth)acrylic-modified polyisoprene, preferably has a molecular weight of 1,000 to 100,000, more preferably 1,000 to 50,000. Hydrogenated products thereof can also be used. Commercially available products include “UC-102M” (molecular weight 17,000) and “UC-203M” (molecular weight 35,000) manufactured by Kuraray Co., Ltd., for example.

Polybutadiene (meth)acrylate oligomer, also called (meth)acrylic-modified polybutadiene, preferably has a molecular weight of 500 to 100,000, more preferably 1,000 to 30,000. Hydrogenated products thereof can also be used. Commercially available products include, for example, "TE2000" (molecular weight: 2000) manufactured by Nippon Soda Co., Ltd.

A (meth)acrylic copolymer having a (meth)acryloyl group is a copolymer containing a monomer having a (meth)acryloyl group, and preferably has a molecular weight of 5,000 to 300,000, more preferably 10,000 to 100,000. The monomer component forming the copolymer is, for example, two or more monomers selected from the group consisting of urethane, isoprene, butadiene and (meth)acrylic acid ester, and the copolymer is unreacted (meth)acryloyl. These can be used in any ratio as long as they have groups. The copolymer may be random polymerization or block polymerization.

The amount of the (meth)acrylate oligomer is preferably 10 to 90 parts by mass, more preferably 20 to 90 parts by mass, based on 100 parts by mass of the total of component (A) and components (B), (C), and (D) described later. It is in the range of 80 parts by mass. By setting it as this range, favorable adhesive performance can be maintained and it is more preferable as an adhesive composition.

[(B) monofunctional (meth)acrylate monomer]
The photocurable adhesive composition of the present invention further contains a monofunctional (meth)acrylate monomer (herein sometimes simply referred to as "component (B)"). A monofunctional (meth)acrylate monomer is an acrylic acid or methacrylic acid ester monomer having one acrylic or methacrylic group. By containing a monofunctional (meth)acrylate monomer, the photocurable adhesive composition of the present invention can impart elongation to the cured product.

The type of monofunctional (meth)acrylate monomer can be selected without particular limitation to the organic group to which the acrylic group or methacrylic group is bonded. Examples of organic groups include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, and cycloalkyl groups. It may be substituted with one or more aryloxy groups, which are groups or structures in which oxygen is bonded to an aryl group. In addition, the alkyl group, alkenyl group, alkynyl group, aryl group, and cycloalkyl group have an ether structure interrupted by one or more oxygen atoms, or a secondary or tertiary amine structure interrupted by one or more nitrogen atoms. may be formed.
Monofunctional (meth)acrylate monomers include, for example, 2-ethylhexyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (Meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, norbornene (meth)acrylate, cyclohexyl (meth)acrylate (CH) , 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, methoxyethyl (meth)acrylate, phenoxyethyl (meth)acrylate (PO), phenoxypolyethylene glycol (meth)acrylate (having a molecular weight of less than 1000), 2-hydroxy-3-phenoxypropyl (meth)acrylate, nonylphenol EO adduct (meth)acrylate, methoxytriethylene glycol (meth)acrylate, It is selected from tetrahydrofurfuryl (meth)acrylate, pentamethylpyrelidyl (meth)acrylate and acryloylmorpholine. One or more of these (meth)acrylate monomers can be used. These (meth)acrylate monomers are commercially available and commercially available grades can be used, or they can be obtained by reacting acrylic acid or methacrylic acid with an alcohol compound.

The amount of the monofunctional (meth)acrylate monomer is preferably 1 to 50 parts by mass, with respect to 100 parts by mass of the total of component (A), component (B), and components (C) and (D) described later. It is preferably 10 to 40 parts by mass. Within this range, elongation can be imparted to the cured product and curing shrinkage can be more effectively suppressed without impairing properties as an adhesive.

[(C) Glycol ether or glycol ester]
The photocurable adhesive composition of the present invention further contains a glycol ether or glycol ester having no (meth)acryloyl group (herein, sometimes simply referred to as "component (C)"). Glycol is a compound having a structure in which two hydroxy groups are present in a chain or cyclic aliphatic hydrocarbon, and "glycol ether" is a structure in which at least one of the two hydroxy groups in glycol is etherified. means. "Glycol ether" thus includes glycol monoethers and glycol diethers. "Glycol ester" means a structure in which at least one of the two hydroxy groups in glycol is esterified. "Glycol ester" thus includes glycol monoesters and glycol diesters. The photocurable adhesive composition of the present invention contains this component as a non-reactive component with the component (A) or component (B), thereby achieving both a lower curing shrinkage rate and a higher dielectric constant. can do.
When the compound of component (C) is described herein, the monovalent linear or cyclic hydrocarbon group described at the beginning of the compound name is not derived from a glycol at at least one of both ends of the molecular chain. means skeleton. When the name of a compound begins with "acid" such as lauric acid, it indicates that the compound is a glycol ester. As in "propylene glycol", when "glycol" is modified with a word meaning an alkylene group such as "propylene" or "butylene", two hydroxyl groups are attached to the ends of the alkylene group such as in 1,3-propylenediol. It means that the diol to which the groups are attached is the skeleton. When simply written as "glycol", it means that it has a skeleton of 1,2-ethylenediol. Therefore, for example, "isopropyl glycol" is a structure ((CH ₃ ) ₂ CH--O--CH ₂ CH ₂ --OH) in which one hydroxy group of 1,2-ethylenediol is etherified with an isopropyl group. means that

Examples of component (C) include the general formula: R ¹ -OX ¹ -(OX ² )n-OR ² , wherein R ¹ is optionally interrupted by an ester group; a chain or cyclic hydrocarbon group having 1 to 12 ^carbon atoms or an acyl group; a hydrocarbon group or an acyl group, and each of X ¹ and X ² is independently a divalent C 2-10 chain or cyclic aliphatic hydrocarbon group optionally interrupted by an ester group; and n is an integer of 0 to 5) can be used. Here, "acyl group" refers to a group in which a monovalent hydrocarbon group is bonded to a carbonyl group (C=O).
R ¹ in the above general formula is a monovalent C 1-12 chain or cyclic hydrocarbon group or an acyl group, and in the case of a hydrocarbon group, examples thereof include C _1-12 alkyl, C _{2 -12} alkenyl, C _2-12 alkynyl, C _6-12 aryl, C _3-12 cycloalkyl or C _2-12 acyl. These may be substituted with an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a cycloalkyl group as long as they satisfy the above carbon number range. In the case of a hydrocarbon group, R ¹ preferably has 1 to 12 carbon atoms, more preferably 3 to 8 carbon atoms. R ¹ is more preferably propyl, isopropyl, n-butyl, isobutyl, 2-ethylhexyl or benzyl. When R ¹ is an acyl group, R ¹ preferably has 2 to 12 carbon atoms, more preferably 4 to 12 carbon atoms. Examples of R ¹ when it is an acyl group include acetyl, butanoyl, heptanoyl, hexanoyl, lauryl or benzoyl.
R ² is a hydrogen atom, a chain or cyclic hydrocarbon group having 1 to 12 carbon atoms, or an acyl group, and when it is a hydrocarbon group or an acyl group, the same preferred examples as those for R ¹ apply. . R ² is more preferably a hydrogen atom.
X ¹ and X ² are divalent C 2-10 linear or cyclic aliphatic hydrocarbon groups, examples of which include C _2-10 alkylene, C _2-10 alkenylene, C _2-10 Alkynylene, C _3-10 cycloalkylene. These may be substituted with an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a cycloalkyl group as long as they satisfy the above carbon number range. In addition, the carbon chain of C _2-10 alkylene, C _2-10 alkenylene or C _2-10 alkynylene may be interrupted by C _3-8 cycloalkylene. Furthermore, one or more of R ¹ , R ² , X ¹ and X ² may be interrupted by an ester group. The position of the carbonyl group relative to the oxygen of the ester group may be on either the left or right side. It can be -C(=O)O- or -OC(=O)-. When n is 1 or more, X ¹ and X ² may each be the same group or different, including the case where n is 2 or more and X ² is 2 or more. These groups are preferably the same group in that they are easy to carry out. X ¹ and X ² are preferably divalent straight-chain hydrocarbon groups, many of which are commercially available and easily available, and are advantageous from the viewpoint of molecular weight, which will be described later. or 3, especially compounds with backbones based on 1,2-ethylene glycol or 1,3-propylene glycol are preferred as component (C). Two bonds of X ¹ and X ² are bonded to oxygen atoms, and X ¹ and X 2 may be bonded to oxygen atoms at two arbitrary positions among carbon atoms of X 1 and X ² . However, since the geminal diol lacks stability, the carbons to which the oxygen atoms are bonded are preferably two different carbon atoms. That is, X ¹ and X ² are more preferably ethylene or propylene.
n is a value indicating the number of repeating units of a glycol chain, and compounds where n is 1 or more, such as diglycols and triglycols, can be used as component (C). More preferably, n ranges from 0 to 2 in terms of availability. As component (C), only one type may be used, or two or more types may be used in combination.

Component (C) has at least one ether bond and optionally an ester group and a hydroxy group due to its molecular structure. Although not bound by any particular theory, it is believed that component (C) obtains the electrical effect of improving the dielectric constant due to the polar structure containing the oxygen atoms of the glycol ether or ester. As long as the structure does not react with acrylic or methacrylic groups, it is considered that the dielectric constant of the adhesive composition can be improved by introducing a polar group. Hydroxy groups, on the other hand, have an effect on compatibility. Therefore, in selecting the component (C), one of the criteria may be the extent to which these groups are contained in the entire molecule. This criterion preferably considers the molecular weight of component (C) along with the number of ether linkages, ester linkages or hydroxy groups. As the molecular weight decreases, the number of these groups or structures per unit mass of component (C) increases.

Focusing on ether bonds, for example, when the number of ether bonds per molecular weight increases, the proportion of polar portions in the composition as a whole relatively increases, which is thought to have a positive effect on the dielectric constant. From this point of view, diglycol, that is, one in which n in the above general formula is 1 is preferable as the component (C). In addition, it is preferable to keep the molecular weight of component (C) low. The lower limit is preferably 1000 or less, more preferably 500 or less, and particularly preferably 300 or less. From the viewpoint of ether bonds in component (C), the number of ether bonds per molecule of component (C), which is obtained by dividing the number of ether bonds in one molecule by the value of the molecular weight, is 0.005 or more. If there is, the effect of the present invention can be exhibited more easily, which is preferable. More preferably, the number of ether bonds per molecular weight of component (C) is 0.006 or more. For glycol monoethers, the number of ether linkages per molecular weight scales with the number of hydroxy groups per molecular weight. For this reason, in the case of monoglycol, when the number of ether bonds per molecular weight of component (C) is 0.010 or less, the total amount of substance of hydroxy groups in the entire adhesive composition does not impair compatibility. It is more preferable because it can be set to a degree. In the case of monoglycol, the number of ether groups per molecular weight of component (C) is more preferably 0.095 or less. When the component (C) is a compound having a plurality of ether groups such as diglycol, the preferred range can be set according to the ratio of the number of ether groups to hydroxy groups. For example, in the case of diglycol, since the number of ether groups is twice the number of hydroxy groups, the number of ether bonds per molecular weight of component (C) is preferably 0.020 or less, more preferably 0.019. More preferably:

Focusing on ester bonds, similarly, the number of ester bonds per molecule, which is obtained by dividing the number of ester bonds in one molecule by the value of the molecular weight, can be used as one of the criteria. An ester bond can also be introduced into the structure constituting the component (C) glycol. In that case, the compound to be the component (C) includes at least R ¹ , R ² , X ¹ and X ² in the general formula: R ¹ -OX ¹ -(OX ² )n-OR ² Those having a structure interrupted by an ester group at one site can be mentioned. Two or more sites may be interrupted by an ester group, and since it can be prepared from a dicarboxylic acid such as adipic acid, it is more preferable to use a structure in which two sites are interrupted. . When it has an ester bond, it is preferable that the number of ester bonds per molecular weight of the component (C) is 0.001 or more, because the effects of the present invention are more likely to be exhibited. More preferably, the number of ester bonds per molecular weight of component (C) is 0.002 or more. When component (C) has an ester group, the number of ester groups per molecular weight may be added to the number of ether bonds, and the total sum may be used as a criterion for selecting component (C).

Hydroxy groups also have polarity and affect the dielectric constant. It is preferable to reduce the number of hydroxy groups by adjusting the molecular weight of (C). When the number of hydroxy groups per molecular weight of component (C), which is obtained by dividing the number of hydroxy groups per molecule by the value of the molecular weight, is 0.010 or less, the number of hydroxy groups in the entire adhesive composition is reduced. It is more preferable because the total amount of the substances can be adjusted so as not to impair the compatibility. More preferably, the number of hydroxy groups per molecular weight of component (C) is 0.0095 or less. The number of hydroxy groups can be reduced to 0 by using a glycol diether or diester. is more preferably 0.001 or more, still more preferably 0.002 or more, and particularly preferably 0.003 or more. However, if the blending amount of component (C) is within the range described later, the adhesive composition can exhibit the desired properties without significantly affecting the compatibility.

From the viewpoint of introducing a structure that affects the dielectric constant into the molecule, it is also preferable to use a compound in which an aromatic ring is introduced into the component (C), such as phenyl ether or benzyl ether of glycol. Since the aromatic ring is considered to have a role similar to a polar group such as an ether bond from the viewpoint of dielectric constant, when the compound of component (C) has an aromatic ring, it is related to the number of ether groups and esters. Instead of numerical values, the sum of the number of ether and ester groups and the number of aromatic rings per molecular weight may be used to describe the amount of component (C). For example, in the case of benzyl glycol (molecular weight 152.19; one ether group; one aromatic ring, the number of aromatic rings per molecular weight = 1 ÷ 152.19 = 0.00657), the ether bond per molecular weight (0.00657), the total number of ether bonds and aromatic rings per molecular weight (0.0657+0.0657=0.1314) may be used as a criterion for selecting the component (C).

Non-limiting examples of the compound corresponding to the component (C) include methyl glycol (methyl cellosolve), ethyl glycol (ethyl cellosolve), butyl glycol (butyl cellosolve) as glycol compounds having one ether bond in one molecule, Ethyldiglycol as a diglycol compound having two ether bonds in one molecule such as isobutyl glycol, t-butyl glycol, isopropyl glycol, butylpropylene glycol, 2-ethylhexyl glycol, methylpropylene glycol, propylpropylene glycol, benzyl glycol, etc. Butyl diglycol (butyl carbitol), isobutyl diglycol, t-butyl diglycol, isopropyl diglycol, butylpropylene diglycol, 2-ethylhexyl diglycol, methylpropylene diglycol, propylpyropyrrylene diglycol, benzyl diglycol, etc. Butyl triglycol etc. are mentioned as a glycol compound of . In addition, 1,2-dimethoxyethane, diglyme, DPDM, and other compounds in which the hydroxy groups of the above compounds are further etherified are also included. Compounds having an ester bond include carboxylic acid monoesters and diesters of glycols. Specific examples of the raw material glycol include ethylene glycol, propylene glycol, ethylene diglycol, propylene diglycol, and polyethylene glycol (PEG). Examples of raw material carboxylic acids include acetic acid, propylene acid, butyric acid, and isobutyric acid. , valeric acid, isopentanoic acid, heptanoic acid, lauric acid, and benzoic acid. More specific examples include lauric acid monoester of tetraethylene glycol (PEG-4 laurate), heptanoic acid diester of tetraethylene glycol (PEG-4 diheptanoate), and the like. Those interrupted by an ester group include diesters of dicarboxylic acids such as oxalic acid, malonic acid, succinic acid and adipic acid, at least one of which is an ester of a glycol, more particularly adipine. acid bis[2-(2-butoxyethoxy)ethyl] and adipate bis(2-butoxyethyl). Some of these compounds are generally available under trade names such as Hysolve and Hymol (registered trademark) (both manufactured by Toho Chemical Industry). Isopropyldiglycol or benzylglycol is more preferably used from the standpoint of availability, handleability, and the like. A commercially available product may be used as component (C), but it can also be produced by a method known to those skilled in the art, such as condensation reaction of glycol and monohydric alcohol.

The amount of component (C) is preferably 1 to 30 parts by mass, more preferably 10 to 25 parts by mass, per 100 parts by mass of components (A), (B), (C) and component (D) described later. be. However, when a component other than component (C) having a hydroxy group is used, it is preferable to reduce the amount of component (C) according to the amount used. Within this range, the dielectric constant can be further increased without impairing the functions of the adhesive composition and the optically transparent resin.

[(D) Photoinitiator]
The photocurable adhesive composition of the present invention further includes a photoreaction initiator capable of initiating a polymerization reaction by light such as ultraviolet rays or an electron beam (in this specification, simply referred to as "component (D)"). there is). As the photoreaction initiator, a general initiator can be used, and commercially available ones can be used. The type thereof can also be appropriately selected by those skilled in the art according to the photocurable component (A) or component (B). Examples of photoinitiators include 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, benzophenone , 2,2-dimethoxy-1,2-diphenylethan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, 2-benzyl-2-dimethyl Amino-1-(4-morpholinophenyl)butanone-1,2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-methyl-1-[4-methylthio]phenyl]-2-morpholinopro pan-1-one, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2-hydroxy-2-methyl-[4-(1 -methylvinyl)phenyl]propanol oligomer, 2-hydroxy-2-methyl-[4-(1-methylvinyl)phenyl]propanol oligomer, 2-hydroxy-2-methyl-1-phenyl-1-propanone, isopropylthioxanthone, Methyl o-benzoylbenzoate, [4-(methylphenylthio)phenyl]phenylmethane, 2,4-diethylthioxanthone, 2-chlorothioxanthone, benzophenone, ethylanthraquinone, benzophenone ammonium salt, thioxanthone ammonium salt, bis(2,6 -dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzophenone, 4- Methylbenzophenone, 4,4'-bisdiethylaminobenzophenone, 1,4 dibenzoylbenzene, 10-butyl-2-chloroacridone, 2,2'bis(o-chlorophenyl)4,5,4',5'-tetrakis (3,4,5-trimethoxyphenyl)1,2'-biimidazole, 2,2'-bis(o-chlorophenyl)4,5,4',5'-tetraphenyl-1,2'-biimidazole , 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoyldiphenyl ether, acrylated benzophenone, bis(η ⁵ -2 ,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, o-methylbenzoylbenzoate, p-dimethylaminobenzoic acid ethyl ester, Examples include isoamylethyl p-dimethylaminobenzoate, active tertiary amine, carbazole/phenone photopolymerization initiator, acridine photopolymerization initiator, triazine photopolymerization initiator, benzoyl photopolymerization initiator and the like. These photoreaction initiators may be used singly or in combination of two or more.

In the present invention, preferred photoinitiators include 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and 1-hydroxy-cyclohexyl-phenyl-ketone, respectively. may be used alone or in combination.

The amount of the photoreaction initiator is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 0.1 part by mass, based on 100 parts by mass in total of components (A), (B), (C) and (D). 1 to 15 parts by mass.

[Photocurable adhesive composition]
As described above, the photocurable adhesive composition of the present invention includes (A) a (meth)acrylate oligomer, (B) a monofunctional (meth)acrylate monomer, and (C) a glycol having no (meth)acryloyl group. Ethers or glycol esters, and (D) a photoinitiator. Preferred blending ratios of these components are as described above. However, the compound of each component including component (C) may have a hydroxy group. From the viewpoint of ensuring sufficient compatibility, the photocurable adhesive composition of the present invention preferably has a smaller number of hydroxy groups in the adhesive composition. It is more preferable to set the mixing ratio so that the number (mol) of hydroxy groups per 100 g of the adhesive composition is less than 0.30. More preferably, the number (moles) of hydroxy groups per 100 g of the adhesive composition is less than 0.25. The lower limit of the number (mol) of hydroxy groups per 100 g of the adhesive composition is more preferably 0.001 or more, more preferably 0.002 or more, because the component (C) may contain hydroxy groups. is more preferable, and 0.003 or more is particularly preferable. The photocurable adhesive composition can be obtained by mixing predetermined amounts of each of these components, and optionally the polyfunctional photocurable monomers and additives described later, using a commercially available mixing device.

The photocurable adhesive composition of the present invention contains at least the above-described components (A), (B), (C) and (D). In addition, it may contain commonly used additives such as plasticizers, tackifiers and antioxidants.

The photocurable adhesive composition of the present invention can further contain a polyfunctional photocurable monomer. A polyfunctional photocurable monomer is a monomer having two or more functional groups in one molecule that cause a photocurable reaction. By adding a polyfunctional photocurable monomer to the photocurable adhesive composition, it is possible to adjust the elasticity when the composition is cured. From the viewpoints of ease of handling, availability, etc., the number of functional groups that cause a photocuring reaction, which the polyfunctional photocurable monomer has, is preferably 2 to 10, more preferably 2 to 4. A preferred example of the polyfunctional photocurable monomer is a polyfunctional (meth)acrylate monomer having a plurality of (meth)acryloyl groups as functional groups.

The polyfunctional (meth)acrylate monomer is not particularly limited as long as it is a (meth)acrylate compound having two or more (meth)acryloyl groups in the molecule. When the composition contains a polyfunctional (meth)acrylate monomer, the crosslink density tends to increase, which is advantageous when it is desired to further improve the elastic modulus compared to using a monofunctional (meth)acrylate monomer alone. . The number of (meth)acryloyl groups in the polyfunctional (meth)acrylate monomer is preferably 2-10, more preferably 2-4.

Such polyfunctional (meth)acrylate monomers include ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, neopentyl glycol di( Aliphatic di(meth)acrylates such as meth)acrylate, diethylene glycol di(meth)acrylate, and triethylene glycol di(meth)acrylate; dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, Alicyclic di(meth)acrylates such as tricyclodecanedimethanol di(meth)acrylate; aliphatic tri(meth)acrylates such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate; meth)acrylate; silicone di(meth)acrylate (e.g., EBECRYL 350, manufactured by Daicel Ornex Co., Ltd.); tri(meth)acrylate of alkylene oxide adduct of trimethylolpropane, tri(meth)acrylate of alkylene oxide adduct of pentaerythritol Tri(meth)acrylate of alkylene oxide adduct of polyol such as acrylate; tetra(meth)acrylate of alkylene oxide adduct of pentaerythritol, alkylene oxide of polyol such as tetra(meth)acrylate of alkylene oxide adduct of ditrimethylolpropane Tetra(meth)acrylate as an adduct and the like can be mentioned.
The amount of these polyfunctional photocurable monomers is preferably 20 parts by mass or less, more preferably 0.1 to 15 parts by mass, with respect to the total 100 parts by mass of components (A), (B), (C) and (D). Department.

The photocurable adhesive composition of the present invention can further contain a plasticizer. Examples of plasticizers include polymers compatible with (meth)acrylate oligomers, oligomers, phthalates, castor oil, xylene resins, terpene resins, and rosin. Examples of oligomers or polymers include polyisoprene-based, polybutadiene-based and xylene-based oligomers or polymers. These softening ingredients are commercially available from ADEKA as the BF series, Kuraray as the LIR series, Degussa as the Polyoil series, and Fudo as the Nikanol series. One type or two or more types of plasticizers can be used as these softening components. The amount of the plasticizer is preferably 40 parts by mass or less, more preferably 35 parts by mass or less with respect to 100 parts by mass in total of components (A), (B), (C) and (D).

The photocurable adhesive composition of the present invention can further contain a tackifier. As tackifiers, silane coupling agents such as vinyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, ethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3- methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene) Propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropyl, methyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis( Examples include triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, and the like. One or more of these tackifiers can be used. The amount of the tackifier is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, with respect to 100 parts by mass in total of components (A), (B), (C) and (D).

The photocurable adhesive composition of the present invention can further contain an antioxidant. Antioxidants include dibutylhydroxytoluene (BHT), 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine , pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,2-thio-diethylenebis[3-(3,5-di-t-butyl- 4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5 -di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, N,N'-hexamethylenebis(3,5- di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tris -(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate, octylated diphenylamine, 2,4-bis[(octylthio)methyl]-O-cresol, isooctyl-3-(3,5 -di-t-butyl-4-hydroxyphenyl)propionate and dibutylhydroxytoluene. One or more of these antioxidants can be used. The amount of the antioxidant is preferably 10 parts by mass or less, more preferably 5 parts by mass or less with respect to 100 parts by mass in total of components (A), (B), (C) and (D).

When light does not hit part of the adhesive composition applied to the adhesive surface due to the structure of the material to be adhered, the photocurable adhesive composition of the present invention is cured with light at the part exposed to light. It is also possible to prepare an adhesive composition of a combined photo-curing and heat-curing type in which the portions not exposed to light are cured by heat using an organic peroxide added in advance as an initiator. Examples of organic peroxides include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters, and peroxydicarbonates. One or more of these organic peroxides can be used. The amount of organic peroxide is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 3 parts by mass, based on 100 parts by mass of components (A), (B), (C), and (D). is. A naphthenic acid metal complex, dimethylaniline, quaternary ammonium salts, and phosphoric acid esters can also be used as curing accelerators for the above organic peroxides.

The photocurable adhesive composition is preferably in the form of a transparent liquid in terms of handleability during application, achieving uniform application and curing, and the fact that the substrate to which it is applied includes an optical display. . Judgment as to whether or not the material is transparent is based on the presence of solids such as turbidity by visual observation, and whether or not the material is liquid is evaluated based on whether or not there is fluidity.

The photocurable adhesive composition of the present invention is cured by the action of light, particularly ultraviolet rays, and adheres the surfaces to which it is applied. Curing is primarily due to addition polymerization of the carbon-carbon double bonds of components (A) and (B) to form a polymer. Since the photocurable adhesive composition of the present invention can be used for adhesion of touch panels, it is preferable that it is transparent even after curing.

The photocurable adhesive composition shrinks in volume due to the shrinkage of the molecular spacing during the curing reaction by light, resulting in shrinkage. However, the photocurable adhesive composition of the present invention has a small shrinkage rate upon curing and does not exert excessive stress on a substrate such as glass on which it is applied. In the photocurable adhesive composition of the present invention, if the cure shrinkage rate is less than 3.0%, the influence of cure shrinkage stress on the coated substrate is reduced, which is preferable.

The photocurable adhesive composition of the present invention has a higher dielectric constant than conventional adhesive compositions for touch panels. Therefore, the photocurable adhesive composition of the present invention can be used as an adhesive covering the entire panel of a touch sensor. A higher relative permittivity is preferable because the sensitivity of the touch panel is improved. The method for measuring the relative dielectric constant includes the method described later, and when the relative dielectric constant (100 kHz) measured by the method is 6.2 or more, the touch panel can achieve sufficient sensitivity, which is preferable. .

Since the photocurable adhesive composition of the present invention has the properties described above, it can , bonding between a touch panel and a protective panel, bonding between an optical display panel and an optical display panel, and bonding between an optical display panel and a parallax barrier. Bonding can be performed by a normal method. For example, first, the photocurable adhesive composition is added to one of the substrates to be adhered, and the entire surface is uniformly coated using a well-known method such as roll coating, spray coating, knife coating, or die coating. The other substrate to be bonded is attached to this, and then the composition is cured by irradiation with light (eg, ultraviolet rays) to bond the two substrates. For example, ultraviolet rays having a wavelength of 250 to 450 nm can be used, and suitable wavelengths can be applied according to the functional groups contained in the adhesive composition. The ultraviolet rays to be irradiated may have a single wavelength, but ultraviolet rays having a wide range of wavelengths as described above can also be irradiated. Although the adhesive composition may be applied to both surfaces of the substrates to be adhered from the viewpoint of enhancing the adhesiveness, it is preferably applied to only one of the substrates from the viewpoint of reducing the thickness of the laminate. It is desirable that the thickness of the coating is small, but from the viewpoint of ensuring sufficient adhesive strength, the thickness after curing is preferably 1.0 mm or less, more preferably 0.7 mm or less. Although the timing of the light irradiation is arbitrary, the light irradiation is normally performed after the two substrates are bonded together and then positioned and temporarily fixed. If there is concern that the applied adhesive will flow and the uniformity of the application will be impaired, before bonding the other substrate, perform pre-curing with a light amount that does not completely cure, It is preferable to bond the other substrate after the adhesive composition has cured to such an extent that it does not flow. Alternatively, only the edge of the coated surface can be cured to form a bank for preventing leakage of the resin, and then the second substrate can be attached. The degree of pre-curing can be appropriately set in consideration of the desired curing rate from the integrated amount of light for complete curing. A commercially available device can be used for the light irradiation, and a person skilled in the art can appropriately set the wavelength and light amount of the light to be irradiated according to each component. Moreover, when a thermal initiator such as the above-mentioned organic peroxide is used together, a step of applying heat can be inserted as needed in the bonding step. By such a method, a laminated body in which substrates such as a protective panel, a parallax barrier, a touch panel and an optical display panel are bonded together can be obtained. One aspect of the present invention also relates to a laminate, particularly an optical display, laminated with the photocurable adhesive composition. As used herein, the term "laminate" refers to a stack of two or more substrates via an adhesive, including both before and after curing the adhesive.

The present invention also relates to an optical display, especially a touch sensor, laminated with the photocurable adhesive composition. These laminates can be incorporated into electronic devices such as televisions, digital cameras, mobile phones, personal computers, and monitors.

The invention is illustrated by the following examples, but the invention is not limited to these examples. Reagents commonly used in Examples and Comparative Examples are as follows.
[Component (A)]
UA-10000B: polyether urethane (meth) acrylate (manufactured by KSM)
[Component (B)]
SR-395: isodecyl acrylate (manufactured by Arkema)
4-HBA: 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.)
[Component (D)]
Irgacure TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF)
I-184: Irgacure 184: 1-hydroxycyclohexylphenyl ketone (manufactured by BASF)
[Other additives]
BF-1000: Epoxidized 1,2-polybutadiene (manufactured by ADEKA)
[Evaluation method]
Evaluation of the photocurable adhesive composition and its cured product was performed as follows.
<Appearance>
The liquid appearance of the photocurable adhesive composition was visually confirmed by filling a transparent container with the resin.
For the appearance of the cured product, a cured resin product having a thickness of 0.5 mm was visually confirmed.
<Cure shrinkage rate>
Cure shrinkage was measured by the JIS K6833 specific gravity cup method.
<Dielectric constant>
The cured product had a measurement area of 30 mmφ and a thickness of 0.5 mm, and was attached to a tester to measure the dielectric constant. The measurement was performed at 100 kHz using an impedance analyzer SI-1260 and a permittivity measurement interface 1296 manufactured by Solartron Analytical.

(Example 1)
50 parts by mass of UA-10000B as component (A), 10 parts by mass each of SR-395 and 4-HBA as component (B), and isobutyl glycol (manufactured by Nippon Nyukazai Co., Ltd.: molecular weight 118.18) as component (C). 20 parts by mass, 0.5 parts by mass each of Irgacure TPO and Irgacure 184 as component (D), and 25 parts by mass of BF-1000 as a plasticizer, to obtain a photocurable adhesive composition. got stuff The resulting composition was molded to have an area of 30 mmφ and a thickness of 0.5 mm, and then irradiated with ultraviolet rays (250-450 nm) to obtain a cured product. For the ultraviolet irradiation, eyegrantage manufactured by eyegraphics was used, and irradiation was performed at an illuminance of 400mW/cm ² (illuminance measurement wavelength: 350nm) and 3000mJ/cm ² .
Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 2)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that isobutyl glycol was replaced with isopropyl glycol (manufactured by Nippon Nyukazai Co., Ltd.; molecular weight: 104.15) as the component (C). Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 3)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that isobutyl diglycol (manufactured by Nippon Nyukazai Co., Ltd.; molecular weight: 162.23) was used as the component (C). Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 4)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that isobutyl glycol was replaced with isopropyl diglycol (manufactured by Nippon Nyukazai Co., Ltd.; molecular weight: 148.20) as component (C). Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 5)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that isobutyl glycol was replaced with butylpropylene glycol (manufactured by Nippon Nyukazai Co., Ltd.; molecular weight: 132.20) as component (C). Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 6)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that isobutyl glycol was replaced with butylpropylene diglycol (manufactured by Nippon Nyukazai Co., Ltd.; molecular weight: 190.28) as the component (C). . Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 7)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that isobutyl glycol was replaced with 2-ethylhexyl glycol (manufactured by Nippon Nyukazai Co., Ltd.; molecular weight: 174.28) as the component (C). . Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 8)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that isobutyl glycol was replaced with 2-ethylhexyldiglycol (manufactured by Nippon Nyukazai Co., Ltd.; molecular weight: 218.33) as component (C). rice field. Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 9)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that isobutyl glycol was replaced with propylpropylene glycol (manufactured by Nippon Nyukazai Co., Ltd.; molecular weight: 118.17) as component (C). Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 10)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that isobutyl glycol was replaced with propylpropylene diglycol (manufactured by Nippon Nyukazai Co., Ltd.; molecular weight: 176.25) as the component (C). . Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 11)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that isobutyl glycol was replaced with benzyl glycol (manufactured by Nippon Nyukazai Co., Ltd.; molecular weight: 152.19) as the component (C). The number of aromatic rings per molecular weight of benzyl glycol is 0.00657, and the sum of the number of ether bonds per molecular weight is 0.01314. Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 12)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that isobutyl glycol was replaced with benzyl diglycol (manufactured by Nippon Nyukazai Co., Ltd.; molecular weight: 196.25) as component (C). The number of aromatic rings per molecular weight of benzyl diglycol is 0.00510, and the sum of the number of ether bonds per molecular weight is 0.01529. Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 13)
A photocurable adhesive composition and its cured product were prepared in the same manner as in Example 1 except that the component (C) was changed from isobutyl glycol to lauric acid PEG-4 (Nonion L-2 manufactured by NOF Corporation: molecular weight 363). got Here, the number of ester groups per molecular weight of PEG-4 laurate is 0.00275, and the sum of the number of ether bonds per molecular weight is 0.01102. Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 14)
A photocurable adhesive composition and its A cured product was obtained. Here, the number of ester groups per molecular weight of PEG-4 diheptanoate is 0.00478, and the sum of the number of ether bonds per molecular weight is 0.01195. Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 15)
A photocurable adhesive composition and its curing were prepared in the same manner as in Example 1, except that isobutyl glycol was replaced with bis(2-butoxyethyl) adipate (D931 manufactured by J-Plus Co., Ltd.: molecular weight 346) as the component (C). got stuff Here, bis(2-butoxyethyl) adipate has a number of aromatic rings per molecular weight of 0.00578, and a sum of the number of ether bonds per molecular weight is 0.01156. Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Example 16)
A photocurable adhesive composition and a cured product thereof were prepared in the same manner as in Example 1, except that isobutyl glycol was replaced with dibutoxyethoxyethyl adipate (Proviplast 01422 manufactured by Proviron Co., Ltd.: molecular weight 434.5) as the component (C). got Here, dibutoxyethoxyethyl adipate has a number of aromatic rings per molecular weight of 0.00460, and the sum of the number of ether bonds per molecular weight is 0.01381. Evaluation and measurement results of various physical properties are shown in Table 1 below.

(Comparative example 1)
A photocurable adhesive composition and a cured product thereof were obtained in the same manner as in Example 1, except that no compound corresponding to component (C) was blended. Evaluation and measurement results of various physical properties are shown in Table 1 below.

All of the photocurable adhesive compositions of the present invention are transparent and can be used as OCR. In addition, it was found that the relative dielectric constant was improved while achieving a low shrinkage rate as compared with the composition of the comparative example which did not contain the component (C). ADVANTAGE OF THE INVENTION The photocurable adhesive composition of this invention achieved high dielectric constant, achieving transparency and a low shrinkage|contraction rate. Therefore, the photocurable adhesive composition of the present invention was shown to be a useful material for laminating liquid crystal panels as an adhesive excellent as a filler for in-cell touch panels.

Claims (6)

(A) (meth)acrylate oligomer,
(B) a monofunctional (meth)acrylate monomer,
A photocurable adhesive composition comprising (C) a glycol ether having no (meth)acryloyl group and having a molecular weight of 100 or more and 500 or less , and (D) a photoreaction initiator. The photocurable adhesive according to claim 1, wherein the component (A) is one or more selected from the group consisting of a polyurethane (meth)acrylate oligomer and a (meth)acrylic copolymer having a (meth)acryloyl group. agent composition. 3. The photocurable adhesive composition according to claim 1, wherein said component (C) is a glycol monoether having no (meth)acryloyl group. The component (C) is isobutyl glycol, isopropyl glycol, isobutyl diglycol, isopropyl diglycol, butyl propylene glycol, butyl propylene diglycol, 2-ethylhexyl glycol, 2-ethylhexyl diglycol, propyl propylene glycol, propyl propylene diglycol, The photocurable adhesive composition according to any one of claims 1 to 3, which is at least one selected from the group consisting of benzylglycol and benzyldiglycol. A laminate laminated with the photocurable adhesive composition according to any one of claims 1 to 4. 6. The laminate according to claim 5, which is an optical display.