Active energy ray curable composition, cured product thereof, and optical adhesive sheet

Abstract

The present invention provides an active energy ray curable composition that yields a cured product having a high refractive index and sufficient light transmittance and tackiness. [Solution] An active energy ray curable composition comprising inorganic oxide particles (A), a dispersant (B), an acrylic resin (C), and a (meth)acrylate monomer (D), wherein the dispersant (B) is a phosphate ester compound having a number average molecular weight (Mn) of 1500 or less, the acrylic resin (C) has a tolerance value of 160 or more, and the refractive index of the cured product of the active energy ray curable composition is 1.58 or more.

Description

[Technical Field]

[0001] The present invention relates to an active energy ray curable composition, a cured product thereof, and an optical adhesive sheet. [Background technology]

[0002] In display devices such as organic electroluminescent (EL) displays, components such as cover glass, metal mesh film, and polarizing plate are laminated. These components of the display device are usually bonded together using optical adhesive sheets.

[0003] For example, Patent Document 1 describes a multilayer adhesive film comprising a first adhesive film having a refractive index of 1.55 or higher and a second adhesive film laminated on one side of the first adhesive film. Patent Document 1 also describes that the first adhesive film in the multilayer adhesive film comprises a cured product of a composition for the first adhesive film comprising an aromatic group-containing (meth)acrylic polymer, a curing agent, and a photoinitiator.

[0004] Furthermore, for example, Patent Document 2 describes an adhesive optical film comprising an optical film and an adhesive layer laminated on the optical film, wherein the adhesive layer includes a high refractive index adhesive layer with a refractive index higher than 1.560. Patent Document 2 also describes that the high refractive index adhesive layer included in the adhesive optical film contains a plasticizer and has a peel strength F1 to a glass plate of 3N / 25mm or more.

[0005] Furthermore, conventionally, optical components have been made from cured products of curable compositions containing inorganic fine particle dispersions. For example, Patent Document 3 describes a method for producing an inorganic fine particle dispersion in which (A) zirconium oxide nanoparticles, (B) a silane coupling agent, (C) a dispersion medium, and (D) a dispersant are supplied to a wet disperser, with at least (D) being supplied last. Patent Document 3 describes an anionic dispersant having an acid group, such as phosphoric acid, a carboxylic acid, sulfuric acid, or a sulfonic acid, or a salt thereof, as the (D) dispersant.

[0006] Furthermore, for example, Patent Document 4 describes an inorganic fine particle dispersion containing inorganic fine particles (A) and a dispersant (B). Patent Document 4 states that zirconium oxide is preferred for the inorganic fine particles (A). Patent Document 4 also states that the dispersant (B) comprises a phosphate ester compound (b1) having at least one (meth)acryloyl group and at least one polyester chain, and a hydroxyl group-containing compound (b2) with a molecular weight of 250 or less. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2023-168312 [Patent Document 2] Japanese Patent Publication No. 2023-151520 [Patent Document 3] International Publication No. 2016 / 093014 [Patent Document 4] International Publication No. 2020 / 250721 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Optical adhesive sheets used to bond components of display devices preferably have a high refractive index and high light transmittance. However, conventional optical adhesive sheets have insufficient refractive index, and there is a need for an even higher refractive index. One possible method for manufacturing optical adhesive sheets with a high refractive index is to use a method that involves curing an active energy ray-curable composition containing a sufficient amount of inorganic oxide particles.

[0009] However, active energy ray curable compositions containing a sufficient amount of inorganic oxide particles tend to become cloudy. Cured products of cloudy active energy ray curable compositions have insufficient light transmittance. Furthermore, cured products of active energy ray curable compositions containing a sufficient amount of inorganic oxide particles lack tackiness, making it difficult to obtain sufficient adhesion. Therefore, with conventional technology, it has been difficult to further increase the refractive index of optical adhesive sheets while ensuring sufficient light transmittance and tackiness.

[0010] The present invention has been made in view of the above problems, and aims to provide an active energy ray curable composition that yields a cured product having a high refractive index and sufficient light transmittance and tackiness.

[0011] Furthermore, the present invention aims to provide a cured product obtained by curing the active energy ray curable composition of the present invention, which has a high refractive index and sufficient light transmittance and tackiness. Furthermore, the present invention aims to provide an optical adhesive sheet obtained by curing the active energy ray curable composition of the present invention, which has a high refractive index and sufficient light transmittance and tackiness. [Means for solving the problem]

[0012] To solve the above problems and realize an active energy ray curable composition that has a high refractive index and sufficient light transmittance and tackiness, the inventors focused on the composition of the active energy ray curable composition and conducted diligent research. As a result, by curing an active energy ray-curable composition containing inorganic oxide particles, a specific dispersant, an acrylic resin having a tolerance value of 160 or more described later, and an acrylate monomer, it was found that a cured product having a high refractive index and sufficient light transmittance and tackiness could be obtained, and the present invention was conceived. The present invention provides the following means.

[0013] [1] An active energy ray-curable composition containing inorganic oxide particles (A), a dispersant (B), an acrylic resin (C), and a (meth)acrylate monomer (D), where the dispersant (B) is a phosphate ester compound having a number average molecular weight (Mn) of 1500 or less, where the acrylic resin (C) has a tolerance value calculated by the following method of 160 or more, An active energy ray-curable composition, wherein the refractive index of the cured product of the active energy ray-curable composition is 1.58 or more.

[0014] [Tolerance value calculation method] Add 0.15 g of acrylic resin to 10 g of acetone and stir in a Erlenmeyer flask until uniform. Place the Erlenmeyer flask on a printed matter, keep the contents at 25°C, and dropwise add ion-exchanged water little by little into the Erlenmeyer flask using a burette while visually checking the typeface through the liquid phase. Then, using the dropwise amount V (mL) of the ion-exchanged water at the time when the typeface cannot be discriminated due to the turbidity of the liquid phase and the mass (0.15 g) of the acrylic resin used for the measurement of the tolerance value, the tolerance value is calculated by the following formula (I). Tolerance value = V / 0.15 (I)

[0015] [2] The active energy ray-curable composition according to [1], wherein the inorganic oxide particles (A) are at least one selected from the group consisting of zirconia, titania, niobium oxide, and barium titanate. [3] The active energy ray curable composition according to [1] or [2], wherein the acrylic resin (C) has a glass transition temperature Tg of 0°C or less and comprises structural units derived from monofunctional acrylate.

[0016] [4] The phosphate ester compound is -[(CH2) a -O-] b An active energy ray curable composition according to [1] or [2], having an alkylene oxide structure represented by -(wherein a is an integer, and b is the average degree of polymerization). [5] The active energy ray curable composition according to [1] or [2], wherein the acrylic resin (C) has a weight-average molecular weight (Mw) of 50,000 or more. [6] The active energy ray curable composition according to [1] or [2], comprising 5 parts by mass or more and 80 parts by mass or less of the inorganic oxide particles (A).

[0017] [7] The active energy ray curable composition according to [1] or [2], wherein the phosphate ester compound comprises a monophosphate ester compound (B-1) comprising a (meth)acryloyl group and a polyester chain, and a diphosphate ester compound (B-2) comprising an aliphatic hydrocarbon group which may have a branch and an ethylene glycol chain.

[0018] [8] The active energy ray curable composition according to [1] or [2], wherein the phosphate ester compound comprises a monophosphate ester compound (B-1) represented by the following formula (1).

[0019] [ka] (In formula (1), R 1 R is a hydrogen atom or a methyl group. 2 (where x is an alkylene chain with 2 to 4 carbon atoms; x is an integer between 4 and 10; y represents the average degree of polymerization and is a value greater than or equal to 1; n is an integer between 1 and 3.)

[0020] [9] The active energy ray curable composition according to [1] or [2], wherein the phosphate ester compound comprises a diphosphate ester compound (B-2) represented by the following formula (2).

[0021] [ka] (In formula (2), m1 is an integer between 5 and 25. m2 represents the average degree of polymerization and is between 2 and 20. m3 is an integer between 0 and 2. m4 is an integer between 1 and 3. X is a terminal group that has a structure capable of hydrogen bonding with other molecules.)

[0022]

[10] In formula (2), X is a phosphate group represented by formula (3), a carboxylic acid group represented by formula (4), an amino group represented by formula (5), a hydroxyl group represented by formula (6), or a carbonyl group represented by formula (7) (R in formula (7) 3 The active energy ray curable composition according to [9], wherein is an alkyl group having a linear or branched structure and may contain an oxygen atom or a sulfur atom, and is selected from the sulfone group represented by the following formula (8).

[0023] [ka]

[0024]

[11] The active energy ray curable composition according to [1] or [2], further comprising a silane coupling agent (E).

[12] The active energy ray curable composition according to [1] or [2], for use in optical adhesive sheets.

[0025]

[13] A cured product obtained by curing the active energy ray curable composition described in [1] or [2].

[14] An optical adhesive sheet obtained by curing an active energy ray curable composition described in [1] or [2]. [Effects of the Invention]

[0026] The active energy ray-curable composition of the present invention comprises inorganic oxide particles (A), a dispersant (B), an acrylic resin (C), and a (meth)acrylate monomer (D), wherein the dispersant (B) is a phosphate ester compound with a number average molecular weight (Mn) of 1500 or less, and the acrylic resin (C) is an acrylic resin with a tolerance value of 160 or more, and the refractive index of the cured product is 1.58 or more. Therefore, the active energy ray-curable composition of the present invention has stably dispersed inorganic oxide particles (A), and by curing, a cured product with a high refractive index and sufficient light transmittance and tackiness can be formed. [Brief explanation of the drawing]

[0027] [Figure 1] Figure 1 is a schematic cross-sectional view illustrating an example of a cured product according to one embodiment of the present invention. [Modes for carrying out the invention]

[0028] The active energy ray curable composition, its cured product, and optical adhesive sheet according to this embodiment will be described in detail below. The scope of the present invention is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the invention. Furthermore, if multiple upper and lower limits are specified for a particular parameter, any upper and lower limit can be combined from among these upper and lower limits to obtain a suitable numerical range.

[0029] In this specification, "~" means a value greater than or equal to the value before the "~" and a value less than or equal to the value after the "~". Also, "(meth)acrylic" is a general term for acrylic and methacrylic. For example, "(meth)acrylate compound" is a general term for acrylate compound and methacrylate compound.

[0030] <Active energy ray curable composition> The active energy ray curable composition according to this embodiment comprises inorganic oxide particles (A), a dispersant (B), an acrylic resin (C), and a (meth)acrylate monomer (D). The active energy ray curable composition of this embodiment preferably contains inorganic oxide particles (A), a dispersant (B), an acrylic resin (C), and a (meth)acrylate monomer (D), along with a silane coupling agent (E) and a photopolymerization initiator (F).

[0031] The active energy ray curable composition according to this embodiment has a refractive index (594 nm) of 1.58 or higher at 25°C. The refractive index of the cured product obtained by curing the active energy ray curable composition of this embodiment is preferably 1.59 or higher, may be 1.60 or higher, or 1.61 or higher. There is no particular upper limit to the refractive index of the cured product, and a higher value is preferable. If anything, from the viewpoint of balancing with the viscosity of the active energy ray curable composition, the refractive index of the cured product is preferably 1.58 or higher and 1.70 or lower, and more preferably 1.59 or higher and 1.69 or lower.

[0032] (Inorganic oxide particles (A)) Known inorganic oxide particles (A) can be used as the active energy ray curable composition in this embodiment. The shape of the inorganic oxide particles (A) is not particularly limited and may be spherical, hollow, porous, rod-shaped, plate-shaped, fibrous, or amorphous. Among the above, the shape of the inorganic oxide particles (A) is preferably spherical because it provides excellent dispersion stability and results in a cured product with high light transmittance and refractive index.

[0033] The material of the inorganic oxide particles (A) is preferably at least one selected from the group consisting of zirconia, titania, niobium oxide, and barium titanate. Among these, the inorganic oxide particles (A) are preferably made of zirconia. The crystal structure of the inorganic oxide particles (A) is not particularly limited. For example, if the inorganic oxide particles (A) are zirconia particles, it is preferable that they be monoclinic in order to obtain a composition that has excellent dispersion stability and a cured product with high light transmittance and refractive index.

[0034] <Zirconia nanoparticles> When the inorganic oxide particles (A) are zirconia particles, it is preferable that they be zirconia nanoparticles. The shape of the zirconia nanoparticles is not particularly limited and examples include spherical, hollow, porous, rod-shaped, fibrous, etc. Among these, the shape of the zirconia nanoparticles is preferably spherical.

[0035] The average primary particle size of the zirconia nanoparticles is preferably 1 nm to 50 nm, and more preferably 1 nm to 30 nm. Furthermore, the crystal structure of the zirconia nanoparticles is not particularly limited, but is preferably monoclinic.

[0036] In this invention, the average primary particle diameter of zirconia nanoparticles can be measured by directly measuring the size of the primary particles from electron microscope images taken using a TEM (transmission electron microscope). Specifically, for example, a method can be used in which the short axis diameter and long axis diameter of the primary particles of individual inorganic particles shown in the electron microscope image are measured, and the average value of these is taken as the average primary particle diameter of the primary particles.

[0037] Specific examples of zirconia nanoparticles according to this embodiment include UEP-100 (average primary particle diameter: 11 nm) manufactured by Daiichi Rare Elements Chemical Industry Co., Ltd., and PCS (average primary particle diameter: 20 nm) manufactured by Nippon Denko Co., Ltd.

[0038] The active energy ray curable composition of this embodiment preferably contains 5 parts by mass or more and 80 parts by mass or less of inorganic oxide particles (A). When the content of inorganic oxide particles (A) is 5 parts by mass or more, the composition yields a cured product with an even higher refractive index. The content of inorganic oxide particles (A) is more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more, as this will yield a cured product with an even higher refractive index.

[0039] Furthermore, if the content of inorganic oxide particles (A) is 80 parts by mass or less, the dispersion stability of the inorganic oxide particles (A) becomes even better, resulting in a composition that is less prone to clouding and yields a cured product with better light transmittance and tackiness. The content of inorganic oxide particles (A) is more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or more.

[0040] (Dispersant (B)) The dispersant (B) contained in the active energy ray curable composition of this embodiment is a phosphate ester compound having a number average molecular weight (Mn) of 1500 or less. Because the number average molecular weight (Mn) of the phosphate ester compound, which is the dispersant (B), is 1500 or less, the dispersion stability of the inorganic oxide particles (A) is further improved, and even with a high content of inorganic oxide particles (A), the composition is less likely to become cloudy, and a cured product with better light transmittance and tack properties can be obtained. The number average molecular weight (Mn) of the phosphate ester compound is preferably 1200 or less, and more preferably 1000 or less.

[0041] The number-average molecular weight (Mn) of the phosphate ester compound contained in the dispersant (B) is preferably 200 or more, and more preferably 400 or more. This is because the function of the dispersant (B) in coating the surface of the inorganic oxide particles (A) and inhibiting aggregation of the inorganic oxide particles (A) in the composition is more pronounced. The phosphate ester compound contained in the dispersant (B) may have a number average molecular weight (Mn) of 1500 or less, and may be only one kind, or two or more kinds, and two or more kinds are preferred.

[0042] The phosphate ester compound contained in the dispersant (B) is -[(CH2) a -O-] b -(In the formula, a is an integer. b is the average degree of polymerization.) It is preferable to contain one or more phosphate ester compounds having an alkylene oxide structure represented by. The reason is that the phosphate ester compound having the above alkylene oxide structure surrounds the inorganic oxide particles (A), making it difficult for the inorganic oxide particles (A) to aggregate in the composition, and effectively improving the dispersion stability of the inorganic oxide particles (A). In addition, the above alkylene oxide structure functions as a hydrophilic group that interacts with the inorganic oxide particles (A) together with the group derived from phosphoric acid, so that the surface of the inorganic oxide particles (A) can be more effectively coated.

[0043] In the above -[(CH2) a -O-] b - In the alkylene oxide structure represented by, a in the formula is an integer, preferably 1 to 10, and more preferably 2 to 5. The above alkylene oxide structure is particularly preferably an ethylene oxide structure (ethylene glycol chain) in which a in the above formula is 2, or a propylene oxide structure in which a in the above formula is 3. In the above -[(CH2) a -O-] b - In the alkylene oxide structure represented by, b in the formula represents the average degree of polymerization, preferably 1 to 20, and more preferably 2 to 15.

[0044] Examples of the phosphate ester compound contained in the dispersant (B) include those having a (meth)acryloyl group, those having a polyester chain, those having an aliphatic hydrocarbon group that may have a branch, and those having an ethylene glycol chain. The dispersant (B) preferably includes, as a phosphate ester compound, a monophosphate ester compound (B-1) containing a (meth)acryloyl group and a polyester chain, and a diphosphate ester compound (B-2) containing an aliphatic hydrocarbon group which may have a branching and an ethylene glycol chain.

[0045] Since the monophosphate ester compound (B-1) contains a (meth)acryloyl group and a polyester chain, it exhibits good adsorption performance to the surface of hydrophilic inorganic oxide particles (A), and can effectively improve the dispersion stability of inorganic oxide particles (A) in the composition. Furthermore, because the monophosphate ester compound (B-1) contains a (meth)acryloyl group and a polyester chain, it copolymerizes with (meth)acrylate monomer (D), contributing to the formation of a cured product in which the elution and migration of components contained in the composition are suppressed.

[0046] Furthermore, since the diphosphate ester compound (B-2) contains an aliphatic hydrocarbon group which may have branches and an ethylene glycol chain, even if the composition contains a (meth)acrylate monomer (D) which is highly hydrophobic and has a low Tg (glass transition temperature), the dispersion stability of the hydrophilic inorganic oxide particles (A) in the composition can be well maintained, and a composition with low viscosity and easy application can be formed.

[0047] When dispersant (B) contains a monophosphate ester compound (B-1) and a diphosphate ester compound (B-2), the synergistic effect of the functions of the monophosphate ester compound (B-1) and the diphosphate ester compound (B-2) further improves the dispersion stability of the inorganic oxide particles (A). As a result, a composition is obtained in which clouding is less likely to occur even with a high content of inorganic oxide particles (A), low viscosity and good coating properties, a cured product with a higher refractive index, and better light transmittance and tack properties.

[0048] The monophosphate ester compound (B-1) may be any phosphate ester compound containing a (meth)acryloyl group and a polyester chain, for example, the monophosphate ester compound (B-1) represented by the following formula (1). The monophosphate ester compound (B-1) represented by formula (1) contained in the dispersant (B) may be only one type or may contain two or more types, and it is preferable that a mixture of multiple monophosphate ester compounds with different numbers of n in formula (1) is included in order to more effectively improve the dispersion stability of the inorganic oxide particles (A).

[0049] [ka] (In formula (1), R 1 R is a hydrogen atom or a methyl group. 2 (where x is an alkylene chain with 2 to 4 carbon atoms; x is an integer between 4 and 10; y represents the average degree of polymerization and is a value greater than or equal to 1; n is an integer between 1 and 3.)

[0050] R in equation (1) 1 This is either a hydrogen atom or a methyl group, and it is preferable that it be a methyl group because it further improves the dispersion stability of the inorganic oxide particles (A). Also, R 2 This is an alkylene chain having 2 to 4 carbon atoms, preferably an alkylene chain having 2 or 3 carbon atoms, and more preferably an ethylene chain having 2 carbon atoms, as this further improves the dispersion stability of the inorganic oxide particles (A).

[0051] In formula (1), x is an integer between 4 and 10, preferably between 4 and 7, and more preferably 4 or 5, as this further improves the dispersion stability of the inorganic oxide particles (A). y represents the average degree of polymerization and is a value greater than or equal to 1, but is not necessarily an integer. y is preferably between 2 and 7, and is preferable to be closer to 1, as this further improves the dispersion stability of the inorganic oxide particles (A). In equation (1), n ​​is an integer between 1 and 3.

[0052] When the dispersant (B) contains the monophosphate ester compound (B-1) represented by formula (1), the dispersion stability of the inorganic oxide particles (A) is good, resulting in a composition with low viscosity, and a cured product with a higher refractive index and better light transmittance and tackiness. As the monophosphate ester compound (B-1) represented by formula (1), commercially available products may be used. Specifically, examples include DISPERBYK-110 (manufactured by BIC Chemie Japan Co., Ltd.) and DISPERBYK-111 (manufactured by BIC Chemie Japan Co., Ltd.).

[0053] The diphosphate ester compound (B-2) may be any phosphate ester compound comprising an aliphatic hydrocarbon group which may have branches and an ethylene glycol chain, and is preferably a phosphate ester compound comprising an alkyl group which may have branches and an ethylene glycol chain.

[0054] The number of carbon atoms in the optionally branched alkyl group contained in the diphosphate ester compound (B-2) is preferably 5 to 25, more preferably 8 to 20, and even more preferably 10 to 17. If the optionally branched alkyl group is branched, the branched chain is preferably an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms.

[0055] Examples of the diphosphate ester compound (B-2) include the diphosphate ester compound (B-2) represented by the following formula (2). The dispersant (B) may contain only one type of diphosphate ester compound (B-2) represented by formula (2), or it may contain two or more types.

[0056] [ka] (In formula (2), m1 is an integer between 5 and 25. m2 represents the average degree of polymerization and is between 2 and 20. m3 is an integer between 0 and 2. m4 is an integer between 1 and 3. X is a terminal group that has a structure capable of hydrogen bonding with other molecules.)

[0057] In equation (2), m1 is an integer between 5 and 25, and is preferably an integer between 8 and 20, and more preferably an integer between 10 and 17, in order to further improve the dispersion stability of the inorganic oxide particles (A). Furthermore, m2 is an integer between 2 and 20, and is preferably an integer between 2 and 15, and more preferably an integer between 3 and 10, as this results in a composition with better tackiness.

[0058] In equation (2), m3 is an integer between 0 and 2, and is preferably an integer between 0 and 1, and more preferably 0, in order to further improve the dispersion stability of the inorganic oxide particles (A). Furthermore, m4 is an integer between 1 and 3, and the possible values ​​are determined according to the structure of the terminal group indicated by X. It is preferable that m4 be 1, as this further improves the dispersion stability of the inorganic oxide particles (A).

[0059] In formula (2), X is a terminal group that has a structure capable of forming hydrogen bonds with other molecules. In formula (2), X is a phosphate group shown in formula (3) below, a carboxylic acid group shown in formula (4) below, an amino group shown in formula (5) below, a hydroxyl group shown in formula (6) below, or a carbonyl group shown in formula (7) below (R in formula (7) 3 It is preferably an alkyl group having a linear or branched structure and which may contain an oxygen atom or a sulfur atom, or one of the sulfone groups represented by the following formula (8). Among the above, X in formula (2) is preferably a phosphate group represented by formula (3) because it further improves the dispersion stability of the inorganic oxide particles (A).

[0060] [ka]

[0061] When the dispersant (B) contains the diphosphate ester compound (B-2) represented by formula (2), the composition yields a cured product with good dispersion stability of inorganic oxide particles (A), a higher refractive index, and better tackiness. As the diphosphate ester compound (B-2) represented by formula (2), commercially available products may be used. Specifically, examples include DISPERBYK-102 (manufactured by Bic Chemie Japan Co., Ltd.).

[0062] The active energy ray curable composition of this embodiment preferably contains a dispersant (B) in an amount of 3 parts by mass or more and 30 parts by mass or less per 100 parts by mass of inorganic oxide particles (A). When the content of dispersant (B) is 3 parts by mass or more, the effects of including dispersant (B) are fully exhibited. As a result, the dispersion stability of inorganic oxide particles (A) is more effectively improved. Consequently, even with a high content of inorganic oxide particles (A), the composition is less likely to become cloudy, and a cured product with a higher refractive index and better light transmittance and tackiness can be obtained. The content of dispersant (B) is more preferably 5 parts by mass or more, even more preferably 7 parts by mass or more, and particularly preferably 9 parts by mass or more.

[0063] Furthermore, if the content of the dispersant (B) is 30 parts by mass or less per 100 parts by mass of inorganic oxide particles (A), it becomes easier to ensure sufficient content of acrylic resin (C) and (meth)acrylate monomer (D), resulting in a composition that is less prone to clouding and yields a cured product with better light transmittance and tackiness. The content of the dispersant (B) is more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less.

[0064] Furthermore, when the dispersant (B) contains a monophosphate ester compound (B-1) and a diphosphate ester compound (B-2), the ratio of the monophosphate ester compound (B-1) to the diphosphate ester compound (B-2) is preferably 1:1 to 10:1 by mass ratio, and more preferably 2:1 to 5:1. When the ratio of the monophosphate ester compound (B-1) to the diphosphate ester compound (B-2) is 1:1 to 10:1 by mass ratio, the synergistic effect of including the monophosphate ester compound (B-1) and the diphosphate ester compound (B-2) becomes more pronounced, and the dispersion stability of the inorganic oxide particles (A) is improved even more effectively.

[0065] (Acrylic resin (C)) The acrylic resin (C) contained in the active energy ray curable composition of this embodiment has a tolerance value of 160 or higher. The acrylic resin (C) contained in the active energy ray curable composition, having a tolerance value of 160 or higher, has good hydrophilicity, and therefore spreads uniformly between adjacent inorganic oxide particles (A) surrounded by the dispersant (B), maintaining an appropriate spacing between adjacent inorganic oxide particles (A) surrounded by the dispersant (B). As a result, the active energy ray curable composition of this embodiment is less prone to aggregation of inorganic oxide particles (A), less prone to clouding even with a high content of inorganic oxide particles (A), and exhibits good dispersion stability of inorganic oxide particles (A).

[0066] In this specification, the "tolerance value" of acrylic resin (C) is the value calculated by the following method. [Method for calculating tolerance values] Add 0.15 g of acrylic resin to 10 g of acetone and stir in an Erlenmeyer flask until homogeneous. Place the Erlenmeyer flask on top of the printed material, maintain the contents at 25°C, and while visually checking the type through the liquid phase, add deionized water dropwise into the Erlenmeyer flask using a burette. Then, using the amount of deionized water added (V, mL) at which the type becomes indistinguishable due to turbidity in the liquid phase, and the mass of acrylic resin used to measure the tolerance value (0.15 g), calculate the tolerance value using the following formula (I). Tolerance value = V / 0.15 ... (I)

[0067] The tolerance value of the acrylic resin (C) having a tolerance value of 160 or higher is preferably 180 or higher, more preferably 200 or higher, even more preferably 220 or higher, and particularly preferably 240 or higher, because it results in a composition that is less prone to clouding even when the content of inorganic oxide particles (A) is increased. The tolerance value of the acrylic resin (C) having a tolerance value of 160 or higher is preferably 500 or lower, more preferably 450 or lower, and even more preferably 400 or lower, because it results in better solubility in (meth)acrylate monomer (D).

[0068] The acrylic resin (C) with a tolerance value of 160 or higher may consist of only one type or two or more types. Examples of acrylic resins (C) with a tolerance value of 160 or higher include Elfort 3154 (manufactured by Resonaq Corporation) and Elfort 3133 (manufactured by Resonaq Corporation).

[0069] The acrylic resin (C) with a tolerance value of 160 or higher preferably has a glass transition temperature Tg of 0°C or lower and contains structural units derived from monofunctional acrylate. This is because it results in a low-viscosity composition and, upon curing, yields a cured product with a high refractive index. The acrylic resin (C) with a tolerance value of 160 or higher is more preferably one with a glass transition temperature Tg of -2°C or lower, and even more preferably one with a Tg of -10°C or lower.

[0070] Furthermore, the acrylic resin (C) with a tolerance value of 160 or higher preferably has a weight-average molecular weight (Mw) of 50,000 or higher, preferably 100,000 or higher, and more preferably 150,000 or higher. When the weight-average molecular weight (Mw) of the acrylic resin (C) with a tolerance value of 160 or higher is 50,000 or higher, the resulting composition yields a cured product with superior tackiness.

[0071] Furthermore, the acrylic resin (C) with a tolerance value of 160 or higher preferably has a weight-average molecular weight (Mw) of 1.5 million or less, and more preferably 700,000 or less. When the weight-average molecular weight (Mw) of the acrylic resin (C) with a tolerance value of 160 or higher is 1.5 million or less, the inorganic oxide particles (A) are less likely to aggregate, the composition is less likely to become cloudy even with a high content of inorganic oxide particles (A), and the dispersion stability of the inorganic oxide particles (A) is better.

[0072] As the acrylic resin (C) with a tolerance value of 160 or higher, commercially available products may be used. Specifically, examples include Elfort 3154 (manufactured by Resona Co., Ltd.), which consists of a mixture of 80 parts by mass of an acrylic resin with a tolerance value of 260 and a weight-average molecular weight (Mw) of 50,000, and 20 parts by mass of isodecyl acrylate, and Elfort 3133 (manufactured by Resona Co., Ltd.), which consists of a mixture of 80 parts by mass of an acrylic resin with a tolerance value of 280 and a weight-average molecular weight (Mw) of 150,000, and 20 parts by mass of isodecyl acrylate.

[0073] The active energy ray curable composition of this embodiment preferably contains 0.2 parts by mass or more and 20 parts by mass or less of acrylic resin (C) having a tolerance value of 160 or more. When the content of acrylic resin (C) is 0.2 parts by mass or more, the effect of including acrylic resin (C) having a tolerance value of 160 or more is fully exhibited. As a result, the composition is less likely to become cloudy even when the content of inorganic oxide particles (A) is increased further, and the dispersion stability of inorganic oxide particles (A) is good. The content of acrylic resin (C) is more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and particularly preferably 4 parts by mass or more.

[0074] Furthermore, if the acrylic resin (C) content is 20 parts by mass or less, it becomes easier to ensure sufficient content of the dispersant (B) and (meth)acrylate monomer (D), resulting in a composition with an even higher refractive index and a cured product with better light transmittance and tackiness. The acrylic resin (C) content is more preferably 17 parts by mass or less, and even more preferably 15 parts by mass or more.

[0075] ((meth)acrylate monomer (D)) The (meth)acrylate monomer (D) contained in the active energy ray curable composition of this embodiment is photopolymerizable, and is used such that the refractive index of the cured product of the active energy ray curable composition is 1.58 or higher. In this embodiment, the (meth)acrylate monomer (D) does not include a compound having a (meth)acryloyl group included as a dispersant (B), nor a compound having a (meth)acryloyl group included as a silane coupling agent (E).

[0076] As the (meth)acrylate monomer (D), for example, monofunctional (meth)acrylates or polyfunctional (meth)acrylates having (meth)acryloyl groups or (meth)acryloyloxy groups, which are used in conventionally known active energy ray curable compositions for optical adhesive sheets, can be used, and oligomers and / or prepolymers may also be used.

[0077] The (meth)acrylate monomer (D) is preferably such that curing the active energy ray curable composition of this embodiment containing it yields a cured product with a glass transition temperature Tg of -2°C or lower, and more preferably a cured product with a Tg of -10°C or lower.

[0078] The (meth)acrylate monomer (D) preferably includes (meth)acrylate (D-1) with a polymer Tg of -2°C or lower. By using (meth)acrylate (D-1) with a polymer Tg of -2°C or lower, it becomes easier to prepare an active energy ray curable composition in which the glass transition temperature Tg of the cured product is -2°C or lower. The polymer Tg may be -4°C or lower, -5°C or lower, or -10°C or lower. Furthermore, the polymer Tg may be -150°C or higher, or -100°C or higher.

[0079] In the present invention, the "polymer Tg" of the (meth)acrylate monomer (D) refers to the Tg (glass transition temperature) of the polymer of the (meth)acrylate monomer (D), and indicates the temperature at which the resin transitions from a glassy state to a rubbery state when heated. The glass transition temperature Tg of the polymer can be measured by methods such as differential scanning calorimeter (DSC), dynamic viscoelasticity measurement (DMA), and thermomechanical analysis (TMA).

[0080] Furthermore, the Tg of a cured product of a composition containing multiple monomers, i.e., the Tg of a copolymer of multiple monomers, decreases as the amount of monomers with low Tg increases, as a homopolymer is present. For example, theoretically, the Tg of a copolymer of monomer mixture M containing monomer 1, monomer 2, .... monomer n can be determined using the following Fox equation.

[0081]

number

[0082] The glass transition temperature (Tg) of a cured product obtained by curing a composition containing multiple monomers varies depending on polymerization conditions, reaction rate, molecular weight, crosslinking points, and the influence of fillers. For this reason, it is difficult to predict the glass transition temperature (Tg) of the cured product of the active energy ray curable composition of this embodiment from the homopolymer Tg of each monomer.

[0083] <Monofunctional (meth)acrylate> A monofunctional (meth)acrylate is a monofunctional (meth)acrylate having one active energy ray curable group. A monofunctional (meth)acrylate may also be a chain-like aliphatic, cyclic, or aromatic (meth)acrylate containing heteroatoms such as halogen atoms, sulfur atoms, oxygen atoms, or nitrogen atoms. The aforementioned monofunctional (meth)acrylate may be used alone or in combination of two or more types.

[0084] Examples of monofunctional (meth)acrylates include aromatic mono(meth)acrylate compounds, aliphatic mono(meth)acrylate compounds, alicyclic mono(meth)acrylate compounds, heterocyclic mono(meth)acrylate compounds, and hydroxyl group-containing mono(meth)acrylate compounds.

[0085] Furthermore, examples of the monofunctional (meth)acrylate include polyoxyalkylene-modified mono(meth)acrylate compounds obtained by introducing polyoxyalkylene chains such as polyoxyethylene chains, polyoxypropylene chains, and polyoxytetramethylene chains into the molecular structure of the various mono(meth)acrylate compounds; and lactone-modified mono(meth)acrylate compounds obtained by introducing a (poly)lactone-derived structure into the molecular structure of the various mono(meth)acrylate compounds.

[0086] Examples of the aromatic mono(meth)acrylate compounds include benzyl(meth)acrylate, phenyl(meth)acrylate, phenoxy(meth)acrylate, phenoxyethyl(meth)acrylate, phenoxyethoxyethyl(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, phenoxybenzyl(meth)acrylate, biphenylmethyl(meth)acrylate, benzylbenzyl(meth)acrylate, phenylphenoxyethyl(meth)acrylate, phenylphenol(EO)n(meth)acrylate, and phenol(EO)n(meth)acrylate.

[0087] Examples of the aliphatic mono(meth)acrylate compounds include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate, tert-butyl(meth)acrylate, n-pentyl(meth)acrylate, n-hexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, and 2-ethylhexyl(meth)acrylate.

[0088] Examples of the alicyclic mono(meth)acrylate compounds include cyclohexyl(meth)acrylate, isobornyl(meth)acrylate, adamantylmono(meth)acrylate, cyclohexylmethyl(meth)acrylate, cyclohexylethyl(meth)acrylate, dicyclopentanyl(meth)acrylate, dicyclopentanyloxyethyl(meth)acrylate, dicyclopentenyl(meth)acrylate, and dicyclopentenyloxyethyl(meth)acrylate.

[0089] Examples of the aforementioned heterocyclic mono(meth)acrylate compounds include glycidyl(meth)acrylate and tetrahydrofurfurylacrylate. Examples of the hydroxyl group-containing mono(meth)acrylate compounds include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate. Examples of the lactone-modified mono(meth)acrylate compound include caprolactone-modified tetrahydrofurfuryl(meth)acrylate.

[0090] [(Meth)acrylate (D-1)] Examples of monofunctional (meth)acrylates (D-1) having a polymer Tg of -2°C or lower include n-butyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxybutyl (meth)acrylate, lauryl (meth)acrylate, isodecyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate. The monofunctional (meth)acrylate (D-1) is preferably an acrylate, and specific examples include isodecyl acrylate (polymer Tg = -60°C), EO-modified phenoxyethyl acrylate (n=4) (polymer Tg = -32°C), and 2-ethylhexyl acrylate (polymer Tg = -70°C).

[0091] [(Meth)acrylate (D-2)] The (meth)acrylate monomer (D) may include (meth)acrylate (D-1) with a polymer Tg of -2°C or lower, as well as (meth)acrylate (D-2) with a polymer Tg greater than -2°C. The polymer Tg of (meth)acrylate (D-2) is preferably 0°C or higher, but may be 5°C or higher, 10°C or higher, or 50°C or lower.

[0092] Examples of monofunctional (meth)acrylates (D-2) having a polymer Tg greater than -2°C include phenoxybenzyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxy (meth)acrylate, and phenoxyethyl (meth)acrylate. A specific example of a monofunctional (meth)acrylate (D-2) is phenoxybenzyl acrylate (polymer Tg = 8°C).

[0093] <Multifunctional (meth)acrylate> The (meth)acrylate monomer (D) may or may not contain a polyfunctional (meth)acrylate in addition to the monofunctional (meth)acrylate described above. A polyfunctional (meth)acrylate is a polyfunctional (meth)acrylate having two or more active energy ray curable groups. Preferably, the polyfunctional (meth)acrylate is a polyfunctional (meth)acrylate having three or more active energy ray curable groups. The polyfunctional (meth)acrylate may be a chain-like aliphatic or cyclic alicyclic or aromatic (meth)acrylic acrylate containing heteroatoms such as halogen atoms, sulfur atoms, oxygen atoms or nitrogen atoms.

[0094] Examples of the polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, tetrabutylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate. Rate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, glycerol di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, caprolactone modified hydroxypivalate neopentyl glycol di(meth)acrylate, tetrabromobisphenol A di(meth)acrylate, hydropivalaldehyde modified trimethylolpropane di(meth)acrylate, bisphenol fluoren (meth)acrylate, bisphenol fluorene (EO) n Di(meth)acrylate, bisphenol A(EO) n Di(meth)acrylate, trimethylolpropane (EO) n Examples of polyfunctional (meth)acrylates include tri(meth)acrylate, 1,4-cyclohexanedimethanol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, glycerol tri(meth)acrylate, alkyl-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetra(meth)acrylate, epoxy(meth)acrylate, urethane(meth)acrylate, and polyester(meth)acrylate.

[0095] These polyfunctional (meth)acrylates can be used individually or in combination of two or more. Among these, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, ditrimethylolpropanetetra(meth)acrylate, reaction products of pentaerythritol and acrylic acid, and reaction products of dipentaerythritol and acrylic acid are preferred because they result in compositions with better curability.

[0096] The content of (meth)acrylate monomer (D) in the active energy ray curable composition of this embodiment is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. When the content of (meth)acrylate monomer (D) is 10% by mass or more, the effects of including (meth)acrylate monomer (D) are fully exhibited, resulting in a composition with good curability.

[0097] Furthermore, the content of (meth)acrylate monomer (D) is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. When the content of (meth)acrylate monomer (D) is 60% by mass or less, the content of inorganic oxide particles (A) can be ensured, resulting in a composition that contains a sufficient amount of inorganic oxide particles (A) and can form a cured product with a high refractive index.

[0098] (Silane coupling agent (E)) The active energy ray curable composition of this embodiment may further contain a silane coupling agent (E). By including the silane coupling agent (E), functional groups are introduced to the surface of the inorganic oxide particles (A), resulting in a composition with lower viscosity in which the inorganic oxide particles (A) are more stably dispersed, and which can form a cured product with a high refractive index.

[0099] Examples of silane coupling agents (E) include (meth)acryloyloxy silane coupling agents such as 3-(meth)acryloyloxypropyltrimethylsilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, and 3-(meth)acryloyloxypropyltriethoxysilane; Vinyl silane coupling agents such as allyltrichlorosilane, allyltriethoxysilane, allyltrimethoxysilane, diethoxymethylvinylsilane, trichlorovinylsilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris(2-methoxyethoxy)silane; Epoxy silane coupling agents such as diethoxy(glycidyloxypropyl)methylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane; Styrene-based silane coupling agents such as p-styryltrimethoxysilane; Amino-based silane coupling agents such as N-2(aminoethyl)3-aminopropylmethyldimethoxysilane, N-2(aminoethyl)3-aminopropyltrimethoxysilane, N-2(aminoethyl)3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-3-aminopropyltrimethoxysilane; Ureidopropyltriethoxysilane and other ureido-based silane coupling agents; Chloropropyl silane coupling agents such as 3-chloropropyltrimethoxysilane; mercapto-silane coupling agents such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane; Sulfide-based silane coupling agents such as bis(triethoxysilylpropyl)tetrasulfide; Isocyanate-based silane coupling agents such as 3-isocyanate-propyltriethoxysilane; Examples include aluminum-based silane coupling agents such as acetalkoxyaluminum diisopropylate.

[0100] These silane coupling agents (E) may be used individually or in combination of two or more. Among the above, it is preferable to use a (meth)acryloyloxy silane coupling agent such as 3-(meth)acryloyloxypropyltrimethoxysilane as the silane coupling agent (E). In particular, it is preferable to use 3-(meth)acryloyloxypropyltrimethoxysilane as the silane coupling agent (E) because of its good compatibility with the (meth)acrylate monomer (D).

[0101] A commercially available silane coupling agent (E) may be used. A specific example of a commercially available silane coupling agent (E) is KBM-503 (compound name: 3-methacryloyloxypropyltrimethoxysilane; manufactured by Shin-Etsu Silicone), which is a silane coupling agent containing a methacrylic group.

[0102] The amount of silane coupling agent (E) contained in the active energy ray curable composition of this embodiment can be in the range of 10 to 30 parts by mass per 100 parts by mass of inorganic oxide particles (A), and preferably in the range of 10 to 20 parts by mass. When the amount of silane coupling agent (E) is 10 parts by mass or more per 100 parts by mass of inorganic oxide particles (A), the effect of including the silane coupling agent (E) becomes significant. As a result, a composition is obtained in which inorganic oxide particles (A) are stably dispersed and a cured product with a lower viscosity and a higher refractive index can be formed.

[0103] Furthermore, if the content of the silane coupling agent (E) is 30 parts by mass or less per 100 parts by mass of inorganic oxide particles (A), the content of inorganic oxide particles (A), dispersant (B), acrylic resin (C), and (meth)acrylate monomer (D) can be sufficiently ensured, resulting in a composition that can form a cured product with a higher refractive index and sufficient light transmittance and tackiness.

[0104] (Photopolymerization initiator (F)) The active energy ray curable composition of this embodiment preferably contains a photopolymerization initiator (F). The photopolymerization initiator (F) has the function of initiating the polymerization of compounds having a (meth)acryloyl group, such as (meth)acrylate monomers (D), by photoexcitation. The photopolymerization initiator (F) is not particularly limited as long as it has the function of initiating the polymerization of compounds having a (meth)acryloyl group.

[0105] Examples of photopolymerization initiators (F) include intramolecular bond cleavage type photopolymerization initiators and intramolecular hydrogen abstraction type photopolymerization initiators. Examples of photopolymerization initiators (F) that can be used include monocarbonyl compounds, dicarbonyl compounds, acetophenone compounds, benzoin ether compounds, acylphosphine oxide compounds, and aminocarbonyl compounds.

[0106] Examples of the intramolecular bond cleavage type photopolymerization initiator (F) include acetophenone derivatives such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenylketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; benzoin derivatives such as benzoin, benzoin methyl ether, and benzoin isopropyl ether; acylphosphine oxide derivatives such as 2,4,6-trimethylbenzoindiphenylphosphine oxide; and benzyl and methylphenylglyoxyesters.

[0107] Examples of the intramolecular hydrogen abstraction type photopolymerization initiator (F) include benzophenone-based compounds such as benzophenone, o-benzoylmethyl-4-phenylbenzophenone, 4,4′-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4′-methyl-diphenyl sulfide, acrylic benzophenone, 3,3′,4,4′-tetra(t-butylperoxycarbonyl)benzophenone, and 3,3′-dimethyl-4-methoxybenzophenone; thioxanthone-based compounds such as 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothiooxanthone; aminobenzophenone-based compounds such as Mihila-ketone and 4,4′-diethylaminobenzophenone; and 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, and camphorquinone.

[0108] Among these, 2,4,6-trimethylbenzoyldiphenylphosphine oxide is preferred as the photopolymerization initiator (F). Furthermore, the above-mentioned photopolymerization initiator (F) may be used alone or in combination of two or more types.

[0109] Commercially available photoinitiators (F) may be used. Specific examples of commercially available photoinitiators (F) include, for example, Omnirad-184, 651, 500, 907, 127, 369, 784, and 2959 from IGM-Resins, and Esacure ONE from TPO-H;DKSH Japan Co., Ltd. Among these, Omnirad-907 and / or Omnirad-TPO-H are preferred from the viewpoint of obtaining a composition with excellent curability even with a small amount of additive. Omnirad-184 is particularly preferred from the viewpoint of obtaining a cured product with less discoloration.

[0110] Furthermore, a specific example of a commercially available photopolymerization initiator (F) is Runtecure 1108 (manufactured by Runtec Chemical Co., Ltd., structural formula or compound name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide).

[0111] The amount of photopolymerization initiator (F) contained in the active energy ray curable composition of this embodiment is preferably in the range of 0.1 parts by mass to 10 parts by mass, and more preferably in the range of 1 part by mass to 5 parts by mass, based on 100 parts by mass of the total nonvolatile content of the active energy ray curable composition. In this embodiment, the total non-volatile content of the active energy ray curable composition is the total mass of the components of the composition after removing the solvent from the active energy ray curable composition.

[0112] [Additives] In addition to the components described above, various additives may be used in the active energy ray curable composition of this embodiment at any stage of the manufacturing process, as necessary, without departing from the objectives of the present invention.

[0113] Examples of such additives include known substances such as foam stabilizers, antioxidants, defoaming agents, fillers, pigments, dyes, colorants, thickeners, surfactants, flame retardants, plasticizers, lubricants, antistatic agents, heat stabilizers, tackifiers, curing catalysts, stabilizers, waxes, and blending resins. These additives are merely examples, and their type and amount are not particularly limited as long as they do not hinder the objective of the present invention.

[0114] Examples of the resins used for blending include conventionally known thermoplastic resins and thermosetting resins. Examples of the aforementioned plasticizers include, for example, dioctyl phthalate (DOP), dibutyl phthalate (DBP); dioctyl adipate, isodecyl succinate; diethylene glycol dibenzoate, pentaerythritol ester; butyl oleate, methyl acetylricinoleate; tricresyl phosphate, trioctyl phosphate; propylene glycol adipate polyester, butylene glycol adipate polyester, and the like. These plasticizers may be used individually or in combination of two or more.

[0115] [solvent] The active energy ray curable composition of this embodiment may contain a solvent. There are no particular restrictions on the solvent used; various known organic solvents can be used.

[0116] Examples of solvents include cyclohexanone, methyl isobutyl ketone, methyl ethyl ketone, acetone, acetylacetone, toluene, xylene, n-butanol, isobutanol, tert-butanol, n-propanol, isopropanol, ethanol, methanol, 3-methoxy-1-butanol, 3-methoxy-2-butanol, ethylene glycol monomethyl ether, ethylene glycol mono-n-butyl ether, 2-ethoxyethanol, 1-methoxy-2-propanol, diacetone alcohol, ethyl lactate, butyl lactate, propylene glycol monomethyl ether, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, 2-ethoxyethyl acetate, butyl acetate, isoamyl acetate, dimethyl adipate, dimethyl succinate, dimethyl glutarate, tetrahydrofuran, and methylpyrrolidone. Among these, methyl ethyl ketone is preferred as the solvent.

[0117] These organic solvents may be used individually or in combination of two or more. Furthermore, the active energy ray curable composition of this embodiment may also contain, for example, a solvent used in the synthesis of any of the components included in the dispersant (B), acrylic resin (C), or (meth)acrylate monomer (D).

[0118] The active energy ray curable composition of this embodiment preferably contains as little solvent as possible. Therefore, it is preferable that the solvent contained in the raw materials of the active energy ray curable composition, as well as the solvent contained in the process of preparing the active energy ray curable composition, be ultimately volatilized. If the active energy ray curable composition of this embodiment contains a solvent, the solvent content in the active energy ray curable composition is preferably 0% to 5% by mass, and more preferably 0% to 0.1% by mass.

[0119] [Refractive index of active energy ray curable composition] The refractive index (589 nm) of the active energy ray-curable composition according to this embodiment at 25°C is preferably 1.55 or higher, preferably 1.57 or higher, may be 1.58 or higher, or may be 1.60 or higher. The upper limit of the refractive index of the active energy ray-curable composition is not particularly limited, but for example, it is preferably 1.70 or lower, and more preferably 1.69 or lower.

[0120] [Viscosity of activated energy ray-curable compositions] The viscosity of the active energy ray-curable composition of this embodiment at 25°C is preferably 50,000 mPa·s or less, more preferably 15,000 mPa·s or less, and even more preferably 6,000 mPa·s or less. It may also be 1,000 mPa·s or more. If the viscosity of the active energy ray-curable composition at 25°C is in the range of 1,000 mPa·s or more and 50,000 mPa·s or less, it has film-forming suitability.

[0121] [Method for preparing an active energy ray-curable composition] The method for preparing the active energy ray curable composition of this embodiment is not particularly limited. For example, the method may include a step of producing an inorganic oxide particle (A) dispersion containing inorganic oxide particles (A), a dispersant (B), and a silane coupling agent (E); a mixing step of mixing the inorganic oxide particle (A) dispersion, an acrylic resin (C), a (meth)acrylate monomer (D), a photopolymerization initiator (F), and other additives as needed to form a mixture; and a volatile component removal step of removing volatile components from the mixture by known methods as needed.

[0122] The mixing method used in the process of producing the inorganic oxide particle (A) dispersion and the mixing process of mixing the components contained in the active energy ray curable composition is not particularly limited, but examples include methods using a dispersion stirrer or a media-type wet disperser. As a media-type wet disperser, any commonly known type can be used without restriction. Examples of media-type wet dispersers include bead mills (such as the Star Mill LMZ-015 manufactured by Ashizawa Finetech Co., Ltd., and the Ultra Apex Mill UAM-015 manufactured by Kotobuki Kogyo Co., Ltd.).

[0123] When manufacturing an inorganic oxide particle (A) dispersion using a media-type wet disperser, the order in which the raw materials are charged into the media-type wet disperser is not particularly limited. By supplying the dispersant (B) last when charging the raw materials into the media-type wet disperser, a composition with excellent dispersion stability of inorganic oxide particles (A) can be manufactured using a small amount of dispersant (B). More specifically, one method involves charging the raw materials for the inorganic oxide particle (A) dispersion other than the dispersant (B), performing one or more pre-dispersion steps, then charging the dispersant (B), and performing the main dispersion step.

[0124] The active energy ray-curable composition of this embodiment comprises inorganic oxide particles (A), a dispersant (B), an acrylic resin (C), and a (meth)acrylate monomer (D), wherein the dispersant (B) is a phosphate ester compound with a number average molecular weight (Mn) of 1500 or less, and the acrylic resin (C) is an acrylic resin with a tolerance value of 160 or more, and the refractive index of the cured product is 1.58 or more. Therefore, the active energy ray-curable composition of this embodiment has stably dispersed inorganic oxide particles (A), and by curing, a cured product with a high refractive index and sufficient light transmittance and tackiness can be formed. Accordingly, the active energy ray-curable composition of this embodiment can be preferably used in applications such as materials for optical adhesive sheets.

[0125] <Cured product> Figure 1 is a schematic cross-sectional view illustrating an example of a cured product according to one embodiment of the present invention. The cured material 1 shown in Figure 1 has a sheet-like shape. As shown in Figure 1, the cured material 1 is sandwiched between a pair of release sheets 2a and 2b, which are facing each other with their release surfaces facing inward. The surface and / or back surface of the cured product 1 shown in Figure 1 may be smooth or may have a fine uneven structure.

[0126] The cured product 1 of this embodiment is obtained by curing the active energy ray curable composition of this embodiment. Therefore, the cured product 1 of this embodiment has a refractive index (594 nm) of 1.58 or higher at 25°C. The refractive index of the cured product 1 is preferably 1.59 or higher, may be 1.60 or higher, or may be 1.61 or higher. The refractive index of the cured product 1 is preferably 1.58 or higher and 1.70 or lower, and more preferably 1.59 or higher and 1.69 or lower.

[0127] If the refractive index (594 nm) of the cured product 1 of this embodiment at 25°C is 1.58 or higher and 1.70 or lower, then, for example, one or more of the following effects (1) to (4) can be obtained. (1) When the cured material is used as an optical lens, it becomes possible to make the optical lens thinner. (2) When the cured material is used as an optical film, the difference in refractive index with the transparent electrode can be reduced, making the transparent electrode less noticeable. (3) By using the cured material as an optical film in combination with a low refractive index layer, an anti-reflective function can be provided. (4) When the cured film is used as a encapsulant for LEDs (light-emitting diodes), the light extraction efficiency from the light-emitting element can be increased.

[0128] The cured product 1 of this embodiment preferably has a glass transition temperature Tg of -2°C or lower, but may also be -4°C or lower, or -9°C or lower. The glass transition temperature Tg of the cured product 1 of this embodiment may also be -50°C or higher.

[0129] [Method for manufacturing hardened products] The method for manufacturing the cured product 1 of this embodiment is not particularly limited. The cured product 1 of this embodiment shown in Figure 1 can be manufactured, for example, by the method described below. To produce the cured product 1 shown in Figure 1, first, release sheets 2a and 2b are prepared. As release sheets 2a and 2b, known transparent resin films such as polyethylene terephthalate (PET) film, glass plates, etc., can be used.

[0130] Next, the active energy ray curable composition of this embodiment is applied to the peel surface of one of the release sheets 2a (or 2b) shown in Figure 1 to form a coating layer of a predetermined thickness (film formation step). In the film formation process, known methods can be used to apply the active energy ray curable composition to the release surface of the release sheet 2a (or 2b). Specifically, as application methods, for example, methods using a rod or wire bar, or various coating methods such as microgravure, gravure, die, curtain, lip, slot or spin can be used.

[0131] Next, as shown in Figure 1, the other release sheet 2b (or 2a) is placed on top of the coating layer made of the active energy ray curable composition obtained in the film formation process, with the release surface of the other release sheet 2b (or 2a) facing it. Then, the coating layer is irradiated with active energy rays through the release sheet 2b (or 2a) to cure the coating layer and obtain a cured product 1 (curing process).

[0132] Furthermore, the following manufacturing method may be used to produce the cured product 1 shown in Figure 1. Specifically, the coating layer made of the active energy ray curable composition obtained in the above-described film formation process is cured by directly irradiating it with active energy rays to form a cured product 1 (curing process). Then, with the release surface of the release sheet 2b (or 2a) facing the cured product 1, the other release sheet 2b (or 2a) is placed on top of the cured product 1.

[0133] In the curing process described above, the active energy ray irradiated onto the coated layer can be any active energy ray that causes the curing reaction of the active energy ray curable composition of this embodiment, without any particular limitations. Examples of active energy rays that can be used include ultraviolet light, visible light, and electron beams, with ultraviolet light being particularly preferred.

[0134] When using ultraviolet light as the active energy ray, sources of ultraviolet light can include, for example, LEDs (light-emitting diodes), fluorescent chemical lamps, black lights, low-pressure, high-pressure, and ultra-high-pressure mercury lamps, metal halide lamps, and sunlight. Among these, it is preferable to use an 80W high-pressure mercury lamp as the source of ultraviolet light.

[0135] In the curing process, for example, when irradiating the coating layer with ultraviolet light using an 80W high-pressure mercury lamp under a nitrogen atmosphere, either through the release sheet 2b (or 2a) or directly, the ultraviolet light with a wavelength of 365 nm should be applied at a rate of 0.5 to 3.0 kJ / m³. 2 It can be irradiated with this energy value. The ultraviolet irradiation intensity may remain constant throughout the process, or the irradiation intensity may be changed during the curing process to fine-tune the physical properties of the cured product after curing.

[0136] In this embodiment, a sheet-like cured product 1 was described as a preferred example of a cured product, but the shape of the cured product is not limited to a sheet shape. For example, the cured product of this embodiment may have a curved shape, such as a concave lens or a convex lens, and can be appropriately selected depending on the application.

[0137] The cured product 1 of this embodiment is a cured product obtained by curing the active energy ray curable composition of this embodiment. Therefore, it has a high refractive index and sufficient light transmittance and tackiness. For this reason, the cured product of this embodiment can be preferably used in a variety of applications such as optical components such as optical lenses, optical films, anti-reflective materials, thin film sealing materials, optical adhesives, optical bonding agents, diffusion microlenses, and optical adhesive sheets.

[0138] <Optical adhesive sheet> The optical adhesive sheet of this embodiment consists of the cured product 1 shown in Figure 1, which is obtained by curing the active energy ray curable composition of this embodiment. The optical adhesive sheet of this embodiment is used as an adhesive sheet, for example, when bonding components that make up a display device such as a smartphone or tablet. Examples of components of a display device that are bonded with the optical adhesive sheet of this embodiment include cover glass, metal mesh film, and polarizing plate.

[0139] The optical adhesive sheet of this embodiment is made of a cured product 1 of the active energy ray curable composition of this embodiment. Therefore, the optical adhesive sheet of this embodiment has a high refractive index and sufficient light transmittance and tackiness. Accordingly, the optical adhesive sheet of this embodiment has a small refractive index difference with the components constituting the display device, can ensure high light extraction efficiency, and has sufficient adhesiveness, making it suitable for use as an adhesive sheet when bonding components of a display device.

[0140] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above. Various modifications, alterations, and combinations of each configuration, element, and feature can be adopted without departing from the spirit of the present invention. [Examples]

[0141] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples. (raw materials) <Inorganic oxide particles (A)> "Zirconia Nanoparticles": Zirconia nanoparticle dispersion, manufactured by Nippon Shokubai, Zircostar® high refractive index nanoparticles ZP-153

[0142] <Dispersant (B)> "Monophosphate ester compound (B-1)" A mixture of multiple monophosphate ester compounds with different numbers of n in the following formula (1); number-average molecular weight (Mn) 400

[0143] [ka] (In formula (1), R 1 R is a methyl group. 2 (where is an ethylene chain with 2 carbon atoms. x is 5. y represents the average degree of polymerization and is 1. n is an integer between 1 and 3.)

[0144] "Diced phosphate ester compound (B-2)" Diceded phosphate ester compound (B-2) represented by the following formula (2); number average molecular weight (Mn) 750; DISPERBYK-102 (manufactured by Bic Chemie Japan Co., Ltd.).

[0145] [ka] (In equation (2), m1 is an integer between 10 and 17. m2 represents the average degree of polymerization and is between 2 and 10. m3 is 0. m4 is an integer between 1 and 2. X is the phosphate group shown in equation (3).)

[0146] <Acrylic resin (C)> "Elfort 3154" (Tolerance value = 260, Glass transition temperature Tg = 0°C or less, Weight-average molecular weight (Mw) 50,000) Product name: Elfort 3154 (Manufactured by Resonac Co., Ltd.) "Elfort 3133" (Tolerance value = 280, Glass transition temperature Tg = 0°C or less, Weight-average molecular weight (Mw) 150,000) Product name: Elfort 3133 (Manufactured by Resonac Co., Ltd.) "Elfort 3902L" (Tolerance value = 150, Glass transition temperature Tg = 0°C or less, Weight-average molecular weight (Mw) 600,000) Product name: Elfort 3902L (Manufactured by Resonac Co., Ltd.) "Elfort 3902" (Tolerance value = 150, Glass transition temperature Tg = 0°C or less, Weight-average molecular weight (Mw) 150,000) Product name: Elfort 3902 (Manufactured by Resonac Co., Ltd.)

[0147] <(meth)acrylate monomer (D)> "Phenoxybenzyl acrylate (polymer Tg=8℃)" manufactured by Green Chemical Co., Ltd. "Isodecyl acrylate (polymer Tg=-60℃)" manufactured by MIWON SPECIALTY CHEMICAL CO.,LTD. "Phenylbenzyl acrylate (polymer Tg=40℃)" manufactured by Shin Nakamura Chemical Co., Ltd.

[0148] "Silane coupling agent (E)" 3-methacryloxypropyltrimethoxysilane: KBM-503 (manufactured by Shin-Etsu Silicone Co., Ltd., 3-(trimethoxysilyl)propyl methacrylate) "Photopolymerization Initiator (F)" 2,4,6-Trimethylbenzoyldiphenylphosphine oxide, Trade name: Runtecure 1108 (manufactured by Runtec Chemical Co., Ltd.)

[0149] (Examples 1-4, Comparative Examples 1-5) The inorganic oxide particles (A) and silane coupling agent (E) listed above were mixed with 60.26 parts by mass of methyl ethyl ketone (MEK) as a solvent in the proportions shown in Table 1 or Table 2, and the mixture was stirred with a dispersion stirrer for 30 minutes to perform the pre-dispersion step. The resulting mixture was mixed with the dispersant (B) described above in the raw materials in the proportions shown in Table 1 or Table 2. Dispersion treatment was then performed using a media-type wet disperser (Star Mill LMZ-015, manufactured by Ashizawa Finetech Co., Ltd.) with zirconia beads having a particle size of 100 μm for a residence time of 100 minutes to obtain an inorganic oxide particle (A) dispersion.

[0150] The obtained inorganic oxide particle (A) dispersion was mixed with the acrylic resin (C), (meth)acrylate monomer (D), and photopolymerization initiator (F) described above in the proportions shown in Table 1 or Table 2. Through the above steps, the active energy ray curable compositions (compositions) of Examples 1 to 4 and Comparative Examples 1 to 5 were prepared.

[0151] The compositions of Examples 1 to 4 and Comparative Examples 1 to 5 obtained in this manner were evaluated for <turbidity during solvent removal>, <refractive index of the liquid>, and <viscosity> using the evaluation methods described below. Furthermore, the cured products obtained by curing the compositions of Examples 1 to 4 and Comparative Examples 1 to 5 were evaluated for <refractive index of the cured product>, <glass transition temperature (Tg)>, and <tackiness> using the evaluation methods described below. The results are shown in Tables 1 and 2.

[0152] (evaluation) <Clouding during solvent removal> The above raw materials were blended to obtain a mixture with the non-volatile content composition shown in Table 1 or Table 2. The resulting mixture was heated under reduced pressure in an evaporator to evaporate and remove the solvent from the mixture. Subsequently, the compositions from which the solvent had been removed were visually observed. The results were evaluated according to the following criteria. [Evaluation Criteria] ○; It did not become cloudy. ×; It became cloudy.

[0153] <Refractive index of liquid> The active energy ray curable composition was directly applied to the prism of an Abbe refractometer, and measurements were taken at 25°C. Measurement wavelength: 589 nm. <Viscosity> The viscosity of the active energy ray curable composition at a temperature of 25°C was measured using an E-type rotational viscometer (TVE-25H, manufactured by Toki Sangyo Co., Ltd.).

[0154] <Refractive index of hardened material> An active energy ray-curable composition was sandwiched between a glass plate and a transparent, easily adhesive PET film (product name: A4300, thickness: 125 μm, manufactured by Toyobo Co., Ltd.), and the composition was spread out with a rubber hand roller until the film thickness was approximately 10 μm. Then, the composition was cured by irradiating it with ultraviolet light through the PET film under the following conditions. Next, the PET film was peeled off from the glass plate together with the cured composition, and the cured composition was formed on the surface of the PET film.

[0155] The refractive index of the cured material obtained in this manner at 25°C was measured using a PRISM COUPLER MODEL 2010 / M (Metricon). "Irradiation conditions" Light source: Ultraviolet light from a high-pressure mercury lamp Total luminous intensity: 400 mJ / cm 2 "Measurement conditions" Wavelength: 594nm Measurement mode: single film

[0156] <Glass transition temperature (Tg)> An active energy ray-curable resin composition was filled between two glass plates, using a 125 μm thick polyethylene terephthalate (PET) film as a spacer. Then, it was heated with a 365 nm wavelength LED lamp at 2000 mJ / cm². 2 The composition was cured by irradiating it with ultraviolet light. Next, the glass plate placed on the opposite side of the light irradiation surface was peeled off. This created a flat, cured film with a thickness of 125 μm on the glass plate.

[0157] Subsequently, the flat, hardened film was peeled off the glass plate, and the DSC curve was measured using a differential scanning calorimeter (X-DSC7000, manufactured by Hitachi High-Tech Science) by dynamic scanning calorimetry (DSC). Heating conditions: 20°C → 80°C, 80°C → -50°C, -50°C → 80°C (10°C / min) Atmosphere: N2 Bread: Al

[0158] <Tuckiness> A flat, hardened film prepared on a glass plate in the same manner as described above for the glass transition temperature (Tg) was pressed against the glass plate. Then, only the upper glass plate that was pressed against the film was lifted, and the tackiness was evaluated according to the following criteria. [Evaluation Criteria] ◎: The flat, hardened film with the glass substrate on the bottom lifted up. ○: The flat, hardened film with the glass substrate on the lower side briefly lifted up but then immediately fell. ×: The flat, hardened film with the glass substrate on the lower side did not lift up.

[0159] [Table 1]

[0160] [Table 2]

[0161] As shown in Table 1, the compositions of Examples 1 to 4, which contain a monophosphate ester compound (B-1) and / or a diphosphate ester compound (B-2) having a number average molecular weight (Mn) of 1500 or less, and an acrylic resin (C) with a tolerance value of 160 or more, all had a good evaluation of turbidity during solvent removal (○) and possessed sufficient light transmittance. Furthermore, as shown in Table 1, the cured products of the compositions of Examples 1 to 4 had good tackiness (○ or ◎). Also, as shown in Table 1, the cured products of the compositions of Examples 1 to 4 all had high refractive indices.

[0162] In contrast, as shown in Table 2, the cured product of Comparative Example 1 composition, which does not contain acrylic resin (C), received a failing grade for tackiness, indicating insufficient adhesiveness. Furthermore, the compositions of Comparative Examples 2 and 3, which did not contain acrylic resin (C) with a tolerance value of 160 or higher, but did contain acrylic resin (C) with a tolerance value of less than 160, received a negative evaluation for turbidity during solvent removal, indicating insufficient light transmittance.

[0163] Furthermore, the cured product of the composition of Comparative Example 4, which did not contain the diphosphate ester compound (B-2), received a failing grade for tackiness, indicating insufficient adhesiveness. Furthermore, the composition of Comparative Example 5, which did not contain the monophosphate ester compound (B-1), received a negative evaluation for turbidity during solvent removal, indicating insufficient light transmittance. [Explanation of Symbols]

[0164] 1…Cured product 2a, 2b... Release sheets

Claims

1. An active energy ray curable composition comprising inorganic oxide particles (A), a dispersant (B), an acrylic resin (C), and a (meth)acrylate monomer (D), The dispersant (B) is a phosphate ester compound having a number average molecular weight (Mn) of 1500 or less. The acrylic resin (C) has a tolerance value of 160 or higher, calculated by the following method. An active energy ray curable composition wherein the refractive index of the cured product of the active energy ray curable composition is 1.58 or higher. [Method for calculating tolerance values] Add 0.15 g of acrylic resin to 10 g of acetone and stir in an Erlenmeyer flask until homogeneous. Place the Erlenmeyer flask on top of the printed material, maintain the contents at 25°C, and while visually checking the type through the liquid phase, add deionized water dropwise into the Erlenmeyer flask using a burette. Then, using the amount of deionized water added (V, mL) at which the type becomes indistinguishable due to turbidity in the liquid phase, and the mass of acrylic resin used to measure the tolerance value (0.15 g), calculate the tolerance value using the following formula (I). Tolerance value = V / 0.15 ... (I)

2. The active energy ray curable composition according to claim 1, wherein the inorganic oxide particles (A) are at least one selected from the group consisting of zirconia, titania, niobium oxide, and barium titanate.

3. The active energy ray curable composition according to claim 1 or claim 2, wherein the acrylic resin (C) has a glass transition temperature Tg of 0°C or less and contains structural units derived from monofunctional acrylate.

4. The phosphate ester compound is -[(CH ２ ) ａ -O-] ｂ The active energy ray curable composition according to claim 1 or claim 2, having an alkylene oxide structure represented by - (wherein a is an integer, and b is the average degree of polymerization).

5. The active energy ray curable composition according to claim 1 or claim 2, wherein the acrylic resin (C) has a weight-average molecular weight (Mw) of 50,000 or more.

6. The active energy ray curable composition according to claim 1 or claim 2, comprising 5 parts by mass or more and 80 parts by mass or less of the inorganic oxide particles (A).

7. The active energy ray curable composition according to claim 1 or claim 2, wherein the phosphate ester compound comprises a first phosphate ester compound (B-1) comprising a (meth)acryloyl group and a polyester chain, and a second phosphate ester compound (B-2) comprising an aliphatic hydrocarbon group which may have a branching and an ethylene glycol chain.

8. The active energy ray curable composition according to claim 1 or claim 2, wherein the phosphate ester compound comprises a first phosphate ester compound (B-1) represented by the following formula (1). 【Chemistry 1】 (In formula (1), R １ R is a hydrogen atom or a methyl group. ２ (where x is an alkylene chain with 2 to 4 carbon atoms; x is an integer between 4 and 10; y represents the average degree of polymerization and is a value greater than or equal to 1; n is an integer between 1 and 3.)

9. The active energy ray curable composition according to claim 1 or claim 2, wherein the phosphate ester compound comprises a diphosphate ester compound (B-2) represented by the following formula (2). 【Chemistry 2】 (In formula (2), m1 is an integer between 5 and 25. m2 indicates the average degree of polymerization and is between 2 and 20. m3 is an integer between 0 and 2. m4 is an integer between 1 and 3. X is a terminal group that has a structure capable of hydrogen bonding with other molecules.)

10. In formula (2), X is a phosphate group represented by formula (3) below, a carboxylic acid group represented by formula (4) below, an amino group represented by formula (5) below, a hydroxyl group represented by formula (6) below, or a carbonyl group represented by formula (7) below (R in formula (7) ３ The active energy ray curable composition according to claim 9, wherein is an alkyl group having a linear or branched structure and may contain an oxygen atom or a sulfur atom, and is selected from the sulfone group represented by the following formula (8). 【Transformation 3】

11. Furthermore, the active energy ray curable composition according to claim 1 or claim 2, comprising a silane coupling agent (E).

12. An active energy ray curable composition according to claim 1 or claim 2, for use in optical adhesive sheets.

13. A cured product obtained by curing the active energy ray curable composition according to claim 1 or claim 2.

14. An optical adhesive sheet obtained by curing the active energy ray curable composition according to claim 1 or claim 2.

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