Adhesive agent, cured product, and member

Abstract

Provided are: an adhesive agent having excellent adhesiveness and heat resistance; a cured product of the adhesive agent; and a member including the cured product. Specifically, the adhesive agent comprises: 0.05-9.5 mass% of a polyfunctional, polymerizable compound (A) represented by general formula (a1); and 90.5-99.95 mass% of a polymerizable monomer (B). [In general formula (a1), R1-R3 each independently represent a hydrogen atom, an alkyl group having 1-6 carbon atoms, an alkenyl group having 2-6 carbon atoms, an aryl group having 6-12 carbon atoms, or an aralkyl group having 7-13 carbon atoms, and R4 represents a (meth)acryloyl group, a vinyl phenyl group, or an alkenyl group having 2-6 carbon atoms. n represents an integer of 1-6.]

Description

Adhesives, cured products and components

[0001] The present invention relates to an adhesive, a cured product of the adhesive, and a member including the cured product.

[0002] Currently, display devices such as liquid crystal displays, plasma displays, organic electroluminescence (EL) displays, and LED displays have a built-in touch panel function or a touch panel attached to the display screen, enabling screen input. In display devices with a touch panel attached, gaps (sometimes referred to as air gaps) between the transparent conductive film and the LCD (Liquid Crystal Display) or organic EL, and between the transparent conductive film and the cover glass, increase reflected light, reducing the visible light and thus reducing visibility. Therefore, the transparent conductive film and the LCD or organic EL, and the transparent conductive film and the cover glass, are often bonded using optical clear resin (OCR). This bonding fills the air gap and reduces reflected light, thereby increasing the visible light and improving visibility. Other benefits of this bonding include improved conformability to uneven surfaces, improved mechanical strength, and prevention of foreign matter contamination.

[0003] Among display devices to which a touch panel is attached, in-vehicle display devices in particular are often exposed to high temperatures, so OCRs are required to have not only high adhesion but also improved heat resistance. A material having both high adhesion and heat resistance is disclosed in Patent Document 1, which includes a block copolymer having a polymer block (A) and a (meth)acrylic polymer block (B), and a vinyl polymer (C), wherein the vinyl polymer (C) has a glass transition temperature within a predetermined range and a number-average molecular weight within a predetermined range, and the content of the vinyl polymer (C) is within a predetermined range relative to 100 parts by mass of the block copolymer.

[0004] Japanese Patent Application Laid-Open No. 2022-007594

[0005] The composition described in Patent Document 1 requires the block copolymer, which is a raw material component, to be synthesized in advance, which requires time and effort. Furthermore, the composition obtained by mixing the components must be dried, and then left to stand at 40°C for 5 days to mature, thereby obtaining an adhesive film, which also requires time. Therefore, there is a need for the development of other adhesives with excellent adhesion and heat resistance.

[0006] Therefore, an object of the present invention is to provide an adhesive having excellent adhesion and heat resistance, to provide a cured product of the adhesive, and to provide a member including the cured product.

[0007] As a result of extensive research, the present inventors have found that the above problems can be solved by the adhesives and the like described in this specification. The present invention includes the following embodiments [1] to

[13] .

[0008] [1] An adhesive comprising: 0.05 to 9.5 mass% of a polyfunctional polymerizable compound (A) represented by the following general formula (a1); and 90.5 to 99.95 mass% of a polymerizable monomer (B): [In general formula (a1), R １ ~R ３ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms; R ４ represents a (meth)acryloyl group, a vinylphenyl group, or an alkenyl group having 2 to 6 carbon atoms. n represents an integer of 1 to 6.] [2] R in the general formula (I) １ and R ２ is a hydrogen atom, and R ３ is a hydrogen atom or a methyl group, n is an integer of 1 to 4, and R ４is a (meth)acryloyl group or a vinylphenyl group. [3] The adhesive according to the above [1] or [2], wherein the component (B) comprises a monofunctional polymerizable monomer (B1). [4] The adhesive according to the above [3], wherein the component (B1) has a (meth)acryloyl group. [5] The adhesive according to the above [3], wherein the component (B1) comprises at least one selected from the group consisting of alkyl or cycloalkyl (meth)acrylates (B1-1) and hydroxyalkyl (meth)acrylates (B1-2). [6] The adhesive according to any one of the above [1] to [5], wherein the component (B) comprises a polyfunctional polymerizable monomer (B2). [7] The adhesive according to the above [6], wherein the component (B2) comprises a poly(meth)acrylate. [8] The adhesive according to the above item [7], wherein the poly(meth)acrylate comprises at least one selected from the group consisting of urethane poly(meth)acrylate and epoxy poly(meth)acrylate. [9] The adhesive according to any one of the above items [6] to [8], wherein the content of the component (B2) relative to the total amount of the component (B) is 20 mass% or less.

[10] The adhesive according to any one of the above items [1] to [9], wherein the component (A) is a polyfunctional polymerizable compound represented by the following general formula (a2): [In general formula (a2), R ５ represents a hydrogen atom or a methyl group.]

[11] The adhesive according to any one of [1] to

[10] above, further comprising 0.1 to 3 mass% of a polymerization initiator (C).

[12] A cured product of the adhesive according to any one of [1] to

[11] above.

[13] A member comprising the cured product according to

[12] above.

[0009] According to the present invention, it is possible to provide an adhesive having excellent adhesion and heat resistance, to provide a cured product of the adhesive, and to provide a member including the cured product.

[0010] 1 is a graph showing the loss tangent (tan δ) measured in Examples 1 to 3 and Comparative Example 1.

[0011] The following describes an embodiment of the present invention. However, the embodiment described below is merely an example for embodying the technical concept of the present invention, and the present invention is not limited to the following description. Furthermore, although preferred embodiments are shown in this specification, a combination of two or more of the individual preferred embodiments is also a preferred embodiment. For matters indicated by numerical ranges, when there are several numerical ranges, the lower and upper limits can be selectively combined to create a preferred embodiment. Note that, in this specification, a numerical range such as "XX to YY" means "XX or more and YY or less." In this specification, the term "(meth)acryloyl group" includes both acryloyl and methacryloyl groups. The term "(meth)acrylate" includes both acrylate and methacrylate. In this specification, the following components used in the production of an adhesive may be at least partially reacted or unreacted in the composition. Furthermore, at least partially reacted components and unreacted components may be mixed.

[0012] [Adhesive] The adhesive of the present embodiment is an adhesive comprising: 0.05 to 9.5 mass % of a polyfunctional polymerizable compound (A) represented by the following general formula (a1) [hereinafter, may be simply referred to as "polyfunctional polymerizable compound (A)" or "component (A)"]; and 90.5 to 99.95 mass % of a polymerizable monomer (B) [hereinafter, may be simply referred to as "component (B)"]: [In general formula (a1), R １ ~R ３ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms; R ４ represents a (meth)acryloyl group, a vinylphenyl group, or an alkenyl group having 2 to 6 carbon atoms, and n represents an integer of 1 to 6.

[0013] The adhesive of this embodiment, particularly due to the inclusion of the specified amount of the polyfunctional polymerizable compound (A), exhibits excellent adhesion and heat resistance. It is believed that this is due to the polyfunctional polymerizable compound (A) having a specific molecular length and a structure capable of crosslinking, resulting in a high crosslink density. However, even if this assumption is incorrect, this does not affect the scope of the present invention. Since the adhesive of this embodiment is liquid at 25°C, it can also be referred to as a "liquid adhesive." In this specification, "liquid" refers to having fluidity, specifically a viscosity value of 10,000 mPa·s or less when measured with a cone-plate type viscometer, preferably 7,000 mPa·s or less, and more preferably 5,000 mPa·s or less. Below, each component contained in the adhesive of the present invention will be described in detail.

[0014] (Polyfunctional Polymerizable Compound (A)) The component (A) is a polyfunctional polymerizable compound and is represented by the general formula (a1). Here, the term "polyfunctional polymerizable" means that the compound represented by the general formula (a1) has a polymerizable functional group R ４ and a polymerizable functional group having the following structure: This is because R １ ~R ３ Even if the polymerizability is reduced depending on the type of n or the value of n, the compound is referred to as a polyfunctional polymerizable compound in the present invention.

[0015] In general formula (a1), R １ ~R ３ R each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms. １ ~R ３ From the viewpoint of adhesiveness and heat resistance, the alkyl group having 1 to 6 carbon atoms that each independently represents is preferably an alkyl group having 1 to 3 carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, an n-propyl group, and an n-hexyl group. １ ~R ３From the viewpoint of adhesiveness and heat resistance, the alkenyl group having 2 to 6 carbon atoms that each independently represents is preferably an alkenyl group having 2 to 4 carbon atoms, more preferably an alkenyl group having 2 or 3 carbon atoms. Examples of the alkenyl group include a vinyl group, an allyl group, a 1-propenyl group, a 1-butenyl group, a 1-pentenyl group, a 3-pentenyl group, a 5-pentenyl group, a 1-hexenyl group, a 3-hexenyl group, and a 6-hexenyl group. １ ~R ３ The aryl group having 6 to 12 carbon atoms, which are each independently represented by R, is preferably an aryl group having 6 to 10 carbon atoms, from the viewpoint of adhesiveness and heat resistance. Examples of the aryl group include a phenyl group, a naphthyl group, and a biphenylyl group. １ ~R ３ From the viewpoint of adhesiveness and heat resistance, the aralkyl group having 7 to 13 carbon atoms represented by each independently is preferably an aralkyl group having 7 to 9 carbon atoms. Examples of the aralkyl group include a benzyl group and a phenethyl group.

[0016] Among the above, from the viewpoint of adhesiveness and heat resistance, R １ and R ２ are each preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom. ３ From the viewpoint of adhesiveness and heat resistance, is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or a methyl group, and even more preferably a methyl group.

[0017] In general formula (a1), R ４ represents a (meth)acryloyl group, a vinylphenyl group, or an alkenyl group having 2 to 6 carbon atoms. ４ From the viewpoint of adhesiveness and heat resistance, the alkenyl group having 2 to 6 carbon atoms represented by R is preferably an alkenyl group having 2 to 4 carbon atoms, more preferably an alkenyl group having 2 or 3 carbon atoms. １ ~R ３ The same as in the case of R ４From the viewpoint of adhesiveness and heat resistance, is preferably a (meth)acryloyl group or a vinylphenyl group, more preferably a (meth)acryloyl group, and even more preferably a methacryloyl group.

[0018] In general formula (a1), n ​​represents an integer of 1 to 6. From the viewpoint of adhesiveness and heat resistance, n is preferably an integer of 1 to 4, more preferably an integer of 1 to 3, even more preferably 1 or 2, and particularly preferably 1.

[0019] From the above, R in general formula (I) １ and R ２ is a hydrogen atom, and R ３ is a hydrogen atom or a methyl group, n is an integer of 1 to 4, and R ４ is also a preferred embodiment in which is a (meth)acryloyl group or a vinylphenyl group, and more preferred embodiments are as described above.

[0020] From the viewpoint of adhesiveness and heat resistance, the component (A) is preferably a polyfunctional polymerizable compound represented by the following general formula (a2). [In general formula (a2), R ５ represents a hydrogen atom or a methyl group.] In general formula (a2), R ５ is preferably a methyl group.

[0021] The polyfunctional polymerizable compound represented by the general formula (a2) can be obtained, for example, by reacting (meth)acrylic acid with an alcohol having an unsaturated double bond structure corresponding to the structure by a known esterification reaction. Note that the polyfunctional polymerizable compound (A) represented by the general formula (a1) can be easily produced by referring to or applying a method for producing the polyfunctional polymerizable compound represented by the general formula (a2).

[0022] (Content of Polyfunctional Polymerizable Compound (A)) The adhesive of the present embodiment contains 0.05 to 9.5 mass %, preferably 0.10 to 9.0 mass %, more preferably 0.15 to 8.0 mass %, even more preferably 0.15 to 5.0 mass %, particularly preferably 0.15 to 3.0 mass %, and most preferably 0.15 to 1.5 mass % of the component (A). When the content of the component (A) in the adhesive of the present embodiment is equal to or greater than the lower limit, excellent adhesive properties are maintained while improving heat resistance. Furthermore, when the content of the component (A) in the adhesive of the present embodiment is equal to or less than the upper limit, the possibility of a decrease in adhesive properties can be avoided. Here, from the viewpoint of further increasing adhesive strength and heat resistance, it is preferable that the content of the component (A) in the adhesive of the present embodiment is not too high. For example, it is preferably 8.0 mass % or less, more preferably 5.0 mass % or less, even more preferably 3.0 mass % or less, and particularly preferably 1.5 mass % or less.

[0023] (Polymerizable Monomer (B)) The component (B) is a polymerizable monomer (however, not including the component (A)). From the viewpoint of adhesiveness and heat resistance, the component (B) may contain a monofunctional polymerizable monomer (B1) [hereinafter, also referred to as the component (B1)], may contain a polyfunctional polymerizable monomer (B2) [hereinafter, also referred to as the component (B2)], or may contain both the monofunctional polymerizable monomer (B1) and the polyfunctional polymerizable monomer (B2).

[0024] - Monofunctional polymerizable monomer (B1) - The component (B1) is a monomer having one polymerizable functional group. Examples of the polymerizable functional group include a (meth)acryloyl group, a vinylphenyl group, and an alkenyl group having 2 to 6 carbon atoms. Examples of the alkenyl group having 2 to 6 carbon atoms include R ４Examples of the polymerizable functional group include those similar to those in the case of (1). From the viewpoint of reactivity, the polymerizable functional group is preferably a (meth)acryloyl group or a vinylphenyl group, more preferably a (meth)acryloyl group, and even more preferably an acryloyl group. The component (B1) may be used alone or in combination of two or more types. Although not particularly limited, it is preferable to use two or more types of the component (B1) in combination, more preferably two to six types in combination, even more preferably two to four types in combination, and particularly preferably three types in combination.

[0025] Examples of the component (B1) having a (meth)acryloyl group include alkyl or cycloalkyl (meth)acrylates (B1-1) such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, and isobornyl (meth)acrylate [however, excluding the hydroxyalkyl (meth)acrylates (B1-2) and halogenated alkyl (meth)acrylates (B1-3) described below]. hydroxyalkyl (meth)acrylates (B1-2) such as 4-hydroxybutyl (meth)acrylate; halogenated alkyl (meth)acrylates (B1-3) such as 2,3-dibromopropyl (meth)acrylate; aromatic (meth)acrylates (B1-4) such as benzyl (meth)acrylate and phenyl (meth)acrylate; silyl group-containing (meth)acrylates (B1-5) such as 3-(meth)acryloyloxypropyltrimethoxysilane and 11-(meth)acryloyloxyundecyltrimethoxysilane. The component (B1) having a (meth)acryloyl group preferably contains at least one selected from the group consisting of alkyl or cycloalkyl (meth)acrylates (B1-1) and hydroxyalkyl (meth)acrylates (B1-2), more preferably contains at least one selected from the group consisting of isobornyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and lauryl (meth)acrylate, and even more preferably contains at least one selected from the group consisting of isobornyl acrylate, 4-hydroxybutyl acrylate, and lauryl acrylate.

[0026] Since the alkyl or cycloalkyl (meth)acrylate (B1-1) tends to improve heat resistance, and the hydroxyalkyl (meth)acrylate (B1-2) tends to improve adhesion, the adhesive of this embodiment preferably contains both of these as component (B1). When the adhesive of this embodiment contains both the alkyl or cycloalkyl (meth)acrylate (B1-1) and the hydroxyalkyl (meth)acrylate (B1-2) as component (B1), the content ratio thereof [(B1-1) / (B1-2)] is preferably 40 / 60 to 90 / 10, more preferably 50 / 50 to 90 / 10, even more preferably 55 / 45 to 85 / 15, particularly preferably 60 / 40 to 85 / 15, and most preferably 65 / 35 to 85 / 15 by mass. Furthermore, when the adhesive of the present embodiment contains both an alkyl(meth)acrylate and a cycloalkyl(meth)acrylate as the component (B1-1), the content ratio thereof [alkyl(meth)acrylate / cycloalkyl(meth)acrylate] is preferably 10 / 90 to 60 / 40, more preferably 15 / 85 to 50 / 50, even more preferably 20 / 80 to 45 / 55, and particularly preferably 25 / 75 to 45 / 55 by mass.

[0027] The alkyl group or cycloalkyl group contained in the alkyl or cycloalkyl (meth)acrylate (B1-1) is preferably an alkyl group having 1 to 20 carbon atoms or a cycloalkyl group having 3 to 20 carbon atoms, more preferably an alkyl group having 4 to 18 carbon atoms or a cycloalkyl group having 4 to 14 carbon atoms, and even more preferably an alkyl group having 8 to 14 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms.

[0028] As the component (B1), a monomer other than the above-mentioned monomers may be used as long as it is a monomer having one polymerizable functional group.

[0029] (Content of Component (B1)) When the component (B) contains the monofunctional polymerizable monomer (B1), the content of the component (B1) in the adhesive of the present embodiment is, from the viewpoints of adhesiveness and heat resistance, preferably 60 to 98.5 mass%, more preferably 65 to 98.5 mass%, and may be 70 to 98.5 mass%, or may be 80 to 98.5 mass%.

[0030] - Polyfunctional Polymerizable Monomer (B2) - Component (B2) is a monomer having two or more polymerizable functional groups. Therefore, component (B2) can also function as a crosslinking agent. The polymerizable functional group is explained in the same manner as in the case of (B1), and the preferred groups are also the same. Component (B2) may contain a poly(meth)acrylate. Examples of the poly(meth)acrylate include urethane poly(meth)acrylate and epoxy poly(meth)acrylate, but other poly(meth)acrylates may also be used. Preferably, the poly(meth)acrylate contains at least one selected from the group consisting of urethane poly(meth)acrylate and epoxy poly(meth)acrylate.

[0031] The urethane poly(meth)acrylate is a poly(meth)acrylate having a polyurethane skeleton. The polyurethane skeleton may contain an aliphatic skeleton (excluding the rubber skeleton and hydrogenated rubber skeleton described below), one or more rubber skeletons selected from the group consisting of polybutadiene and polyisoprene, one or more hydrogenated rubber skeletons selected from the group consisting of hydrogenated polybutadiene and hydrogenated polyisoprene, or one or more skeletons selected from the group consisting of polyether skeletons, polycarbonate skeletons, and polyester skeletons. The urethane poly(meth)acrylate may be a urethane di(meth)acrylate. There are no particular restrictions on the weight average molecular weight (Mw) of the urethane poly(meth)acrylate, but from the viewpoint of operability, it is preferably 1,000 to 30,000, more preferably 2,500 to 15,000, even more preferably 3,000 to 10,000, and particularly preferably 3,500 to 7,500. In this specification, the weight average molecular weight is a weight average molecular weight calculated in terms of polystyrene obtained by measurement using gel permeation chromatography (GPC). Commercially available products can be used as the urethane poly(meth)acrylate. Examples of commercially available products include UV-3700B (manufactured by Mitsubishi Chemical Corporation, Mw: 38,000), UA10000B (manufactured by KSM Corporation, Mw: 25,000), UN7700 (manufactured by Negami Chemical Industrial Co., Ltd., Mw: 20,000), UN-9200A (manufactured by Negami Chemical Industrial Co., Ltd., Mw: 15,000), UN-9000H (manufactured by Negami Chemical Industrial Co., Ltd., Mw: 5,000), and EBECRYL (registered trademark) 230 (manufactured by Daicel-Allnex Corporation, Mw: 5,000).

[0032] Examples of the epoxy poly(meth)acrylate include bisphenol-type epoxy(meth)acrylate, novolac-type epoxy(meth)acrylate, aliphatic-type epoxy(meth)acrylate, etc. The weight-average molecular weight of the epoxy poly(meth)acrylate is not particularly limited, but from the viewpoint of operability, it is preferably 200 to 3,000, more preferably 300 to 1,700, even more preferably 300 to 1,300, and particularly preferably 300 to 1,000.

[0033] Other poly(meth)acrylates, that is, poly(meth)acrylates other than the urethane poly(meth)acrylate and the epoxy poly(meth)acrylate, include, for example, di(meth)acrylates such as dipropylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and tricyclodecane dimethanol di(meth)acrylate; tri(meth)acrylates such as trimethylolpropane tri(meth)acrylate, trimethylolpropane ethoxy tri(meth)acrylate, and pentaerythritol tri(meth)acrylate; tetra(meth)acrylates such as dipentaerythritol ethoxy tetra(meth)acrylate and ditrimethylolpropane tetra(meth)acrylate; and hexa(meth)acrylates such as dipentaerythritol hexa(meth)acrylate.

[0034] (Content of Component (B2)) When the component (B) contains a monofunctional polymerizable monomer (B2), the content of the component (B2) in the adhesive of the present embodiment is, from the viewpoints of adhesiveness and heat resistance, preferably 1 to 40% by mass, more preferably 3 to 35% by mass, and may be 5 to 30% by mass, or may be 5 to 15% by mass. Furthermore, from the viewpoints of adhesiveness and heat resistance, the content of the component (B2) relative to the total amount of the component (B) is preferably 20% by mass or less, more preferably 15% by mass or less, with no particular lower limit, and may be 1% by mass or more, 3% by mass or more, or 5% by mass or more.

[0035] (Content of Polymerizable Monomer (B)) From the viewpoints of adhesiveness and heat resistance, the adhesive of the present embodiment contains the component (B) in an amount of 90.5 to 99.95 mass%, preferably 91 to 99.90 mass%, more preferably 92 to 99.85 mass%, even more preferably 95 to 99.85 mass%, particularly preferably 97 to 99.85 mass%, and most preferably 98.5 to 99.85 mass%.

[0036] In the adhesive of this embodiment, the total content of the (A) component and the (B) component may be 100% by mass, or the total content including the (C) component described below [(A) + (B) + (C)] may be 100% by mass, or the total content including the (C) component and other components described below [(A) + (B) + (C) + other components] may be 100% by mass.

[0037] (C) Polymerization Initiator From the viewpoint of further improving the adhesive properties and adhesion speed, the adhesive of the present embodiment preferably further contains 0.1 to 3 mass % of a (C) polymerization initiator, and more preferably contains 0.5 to 2 mass % of a (C) polymerization initiator. The polymerization initiator may be a photopolymerization initiator, a thermal polymerization initiator, or both a photopolymerization initiator and a thermal polymerization initiator.

[0038] The photopolymerization initiator may be a known photopolymerization initiator, such as an acetophenone-based polymerization initiator, a benzophenone-based polymerization initiator, a Michler's ketone-based polymerization initiator, a benzoin-based polymerization initiator, a thioxanthone-based polymerization initiator, an acylphosphine oxide-based polymerization initiator, or a titanocene-based polymerization initiator. Among these, acetophenone-based polymerization initiators and benzophenone-based polymerization initiators are preferred, with acetophenone-based polymerization initiators being more preferred. One type of photopolymerization initiator may be used alone, or two or more types may be used in combination. When the adhesive of this embodiment contains a photopolymerization initiator, it may further contain a sensitizer. Examples of sensitizers include n-butylamine, di-n-butylamine, tri-n-butylphosphine, allylthiouric acid, triethylamine, and diethylaminoethyl methacrylate.

[0039] As the thermal polymerization initiator, known thermal polymerization initiators can be used, such as azo compounds, peroxides, persulfates, and pinacol. Among these, azo compounds, peroxides, and persulfates are preferred as the thermal polymerization initiator. One type of thermal polymerization initiator may be used alone, or two or more types may be used in combination. When the adhesive of this embodiment contains a thermal polymerization initiator, it may further contain a reducing agent. By containing a reducing agent, the amount of thermal polymerization initiator used can be reduced. Examples of combinations of thermal polymerization initiators and reducing agents include a combination of the persulfates with a reducing agent such as sodium metabisulfite and sodium bisulfite; and a combination of the peroxide with a tertiary amine.

[0040] (Other Components) The adhesive of the present embodiment may or may not further contain other components. When the adhesive of the present embodiment contains other components, the content of the other components is preferably 0.1 to 5 mass %, more preferably 0.1 to 2 mass %, from the viewpoints of adhesiveness and adhesion speed. When the adhesive of the present embodiment contains two or more other components, it is preferable that the content of each of them is within the above range. Examples of the other components include, but are not limited to, sensitizers, reducing agents, plasticizers, fillers, antioxidants, preservatives, thickeners, pigments, etc. The other components may be used alone or in combination.

[0041] The adhesive of the present embodiment can be obtained by mixing the component (A), the component (B), and optionally the component (C), as well as other components as necessary, preferably at 5 to 60° C., more preferably at 15 to 55° C., and even more preferably at 20 to 50° C. Among these, when a component having a weight-average molecular weight of 4,000 or more is used, it is preferable to use a higher mixing temperature from the viewpoint of operability; for example, 30 to 60° C. is preferred, and 40 to 60° C. is more preferred, although this temperature is not particularly limited.

[0042] [Cured Product] When the adhesive of this embodiment contains a photopolymerization initiator, a cured product of the adhesive can be obtained by irradiating it with active energy rays. The active energy rays can be light rays, electromagnetic waves, particle beams, or a combination of these. However, from the viewpoints of curing speed, availability of irradiation equipment, cost, etc., ultraviolet rays and electron beams are preferred, with ultraviolet rays being more preferred. For ultraviolet irradiation, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, chemical lamps, LEDs, etc., which emit light in the wavelength range of 150 to 450 nm can be used. The cumulative light dose of the active energy rays is preferably 500 to 10,000 mJ / cm. 2 , more preferably 1,000 to 5,000 mJ / cm 2 , and more preferably 3,000 to 4,000 mJ / cm 2 When the integrated light amount of the active energy rays is equal to or greater than the lower limit, the adhesive can be cured well, and when it is equal to or less than the upper limit, the adhesive can be prevented from deteriorating. When the adhesive of this embodiment contains a thermal polymerization initiator, a cured product of the adhesive can be obtained by heating. The heating temperature is preferably 50 to 250°C, more preferably 70 to 200°C. The heating time varies depending on the type of thermal polymerization initiator, the types of components in the adhesive, the reaction temperature, etc., and can be adjusted as appropriate.

[0043] From the viewpoint of heat resistance, it is ideal for the cured product of the adhesive of this embodiment to maintain as high a tan δ as possible over a wide temperature range, and tan δ in the temperature range in which the adhesive is applied is preferably 0.18 or more, more preferably 0.4 or more, even more preferably 0.5 or more, and particularly preferably 0.6 or more, with no particular upper limit, and may be 1.5 or less, or 1.2 or less. The temperature range in which the composition is applied includes, for example, a temperature range including 60°C.

[0044] [Component] The present invention also provides a component comprising a cured product of the adhesive of this embodiment. For example, when manufacturing a display device by bonding a touch panel, the adhesive of this embodiment can be introduced between a transparent conductive film and an LCD or organic EL display, and between a transparent conductive film and a cover glass, and the adhesive can be cured by irradiating with active energy rays or by heating, thereby producing a component comprising a cured product of the adhesive of this embodiment. Components comprising a cured product of the adhesive of this embodiment are not particularly limited, and examples include display devices such as liquid crystal displays, plasma displays, organic EL displays, and LED displays.

[0045] The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0046] In the Examples and Comparative Examples, the adhesive strength was measured and the heat resistance was evaluated according to the following methods: (Measurement Methods) (1) Adhesive Strength For the evaluation samples produced in the Examples or Comparative Examples, the adhesive strength between the glass and the cured adhesive was measured using an autograph "AG-IS 5KN" (manufactured by Shimadzu Corporation) by pulling the PET film at an angle of 180° at 300 mm / min at 23°C.

[0047] (2) Heat Resistance Using a dynamic viscoelasticity measuring device "Reogel-E4000" (manufactured by UBM Corporation), the loss tangent (tan δ) was measured at a frequency of 15 Hz, a heating rate of 3°C / min, and a temperature range of -50 to 150°C, and the resulting tan δ was used as an index of heat resistance. The tan δ peak is located on the high temperature side, and the higher the tan δ, the better the heat resistance. Table 1 shows the tan δ peak top temperature and tan δ at 60°C.

[0048] [Examples 1 to 3 and Comparative Example 1] In Example 1 and Comparative Example 1, the components shown in Table 1 were mixed in the amounts shown in Table 1 at 50°C, and in the other examples at 25°C, to obtain adhesives. The adhesives obtained were sandwiched between PET film (manufactured by Toyobo Co., Ltd.) and alkali-free glass (manufactured by AS ONE Corporation) so that the thickness of the adhesive before curing was 100 μm, and 3,200 mJ / cm was applied using a UV irradiator "CSOT-40D" (manufactured by GS Yuasa Corporation). ２ A component in which the PET film and the alkali-free glass were bonded together was obtained by irradiating the component with UV light from the alkali-free glass side at an integrated light intensity of 1000 nm. This component was used as an evaluation sample, and measurements were carried out according to the above-mentioned measurement methods. The results are shown in Table 1. Figure 1 also shows a graph of the loss tangent (tan δ) measured to evaluate heat resistance in Examples 1 to 3 and Comparative Example 1.

[0049]

[0050] The compounds represented by the abbreviations in Table 1 are as follows: Component (A) IPEMA: isoprenyl methacrylate, manufactured by Kuraray Co., Ltd. AMA: Allyl methacrylate, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0051] Component (B) Component (B1) IBOA: isobornyl acrylate LA: lauryl acrylate 4HBA: 4-hydroxybutyl acrylate Component (B2) EB230: "EBECRYL (registered trademark) 230", aliphatic urethane diacrylate, weight average molecular weight 5,000, manufactured by Daicel Allnex Corporation

[0052] Component (C): 1-hydroxycyclohexyl phenyl ketone, manufactured by Tokyo Chemical Industry Co., Ltd., an acetophenone-based polymerization initiator

[0053] As shown in Table 1 and Figure 1, adhesives containing predetermined amounts of both component (A) and component (B) (each Example) exhibit excellent adhesive strength, and the tan δ peak top is located on the higher temperature side, while tan δ itself is also improved. It is believed that a high tan δ at high temperatures makes it easier to maintain the shape at high temperatures, which leads to improved heat resistance as an adhesive. On the other hand, Comparative Example 1, which is a composition that does not contain component (A), exhibits insufficient adhesive strength, the tan δ peak top is located on the lower temperature side, and tan δ itself is also lower than in the Examples, so it can be said that the heat resistance as an adhesive is inferior.

Claims

1. 0.05 to 9.5% by mass of a polyfunctional polymerizable compound (A) represented by the following general formula (a1), and Polymerizable monomer (B) 90.5 to 99.95% by mass Including, adhesive. 【Chemistry 1】 [In general formula (a1), R １ ~R ３ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms; R ４ represents a (meth)acryloyl group, a vinylphenyl group, or an alkenyl group having 2 to 6 carbon atoms; and n represents an integer of 1 to 6.

2. R in the general formula (I) １ and R ２ is a hydrogen atom, R ３ is a hydrogen atom or a methyl group, n is an integer from 1 to 4, and R ４ The adhesive of claim 1 , wherein is a (meth)acryloyl group or a vinylphenyl group.

3. The adhesive according to claim 1 , wherein the component (B) comprises a monofunctional polymerizable monomer (B1).

4. The adhesive according to claim 3 , wherein the component (B1) has a (meth)acryloyl group.

5. The adhesive according to claim 3, wherein the component (B1) comprises at least one member selected from the group consisting of alkyl or cycloalkyl (meth)acrylates (B1-1) and hydroxyalkyl (meth)acrylates (B1-2).

6. The adhesive according to claim 1 , wherein the component (B) comprises a polyfunctional polymerizable monomer (B2).

7. The adhesive of claim 6 , wherein the (B2) component comprises a poly(meth)acrylate.

8. The adhesive of claim 7 , wherein the poly(meth)acrylate comprises at least one selected from the group consisting of urethane poly(meth)acrylates and epoxy poly(meth)acrylates.

9. The adhesive according to claim 6 , wherein the content of the component (B2) relative to the total amount of the component (B) is 20 mass % or less.

10. The adhesive according to claim 1 , wherein the component (A) is a polyfunctional polymerizable compound represented by the following general formula (a2): 【Chemistry 2】 [In general formula (a2), R ５ represents a hydrogen atom or a methyl group.

11. The adhesive according to claim 1, further comprising 0.1 to 3 mass % of a polymerization initiator (C).

12. A cured product of the adhesive according to any one of claims 1 to 11.

13. A member comprising the cured product according to claim 12.

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