Adhesive for optical member, optical element, and optical device

Abstract

Provided are an adhesive for an optical member, an optical element, and an optical device, the adhesive for an optical member including an alicyclic epoxy compound, an oxetanyl group-containing compound, a hindered amine-based light stabilizer, and an antioxidant, in which a cured product of the adhesive for the optical member having a thickness of 100 μm, produced by irradiation with light having a wavelength of 365 nm at an energy density of 3000 mJ / cm2, exhibits an absolute value of refractive index difference less than 0.002 before and after a high-temperature and high-humidity test in which the cured product is exposed to an environment at a temperature of 65°C and a humidity of 90% RH for 24 hours.

Description

Adhesives for optical components, optical elements, and optical instruments

[0001] This disclosure relates to adhesives for optical components, optical elements, and optical devices.

[0002] Currently, with the spread of 5G and generative AI, devices are being developed that use technology to virtually augment the real world by overlaying virtual information onto the real world that humans perceive (i.e., AR: Augmented Reality).

[0003] An adhesive for optical components used in optical imaging elements and the like that which form images in the air is known in which the amount of fluoride ions extracted from the cured product is below a specific amount (Patent Document 1). Even when the above-mentioned adhesive for optical components is used to bond optical components containing metal, deterioration of the optical components can be suppressed.

[0004] Patent Document 1: International Publication No. 2024-171602

[0005] As a device for realizing augmented reality (AR), glasses-type devices called AR glasses are attracting attention. Some AR glasses have a laminated structure in which transparent optical components are bonded together with adhesive. In this case, the adhesive must have transparency in its cured form and match the refractive index of the optical components. However, for example, the optical properties of the adhesive, such as the refractive index, may change over time due to changes in the cured adhesive.

[0006] One embodiment of this disclosure aims to solve the problem of providing an adhesive for optical components in which changes in optical properties are suppressed. Another embodiment of this disclosure aims to solve the problem of providing an optical element and an optical device in which changes in optical properties are suppressed.

[0007] The following embodiments are included as specific means for solving the above problems: <1> An adhesive for optical components comprising an alicyclic epoxy compound, an oxetanyl group-containing compound, a hindered amine-based light stabilizer, and an antioxidant, wherein the adhesive for optical components is exposed to light with a wavelength of 365 nm at an energy density of 3000 mJ / cm². ２An adhesive for optical components, manufactured by irradiation, having a thickness of 100 μm, wherein the cured product has an absolute value of the difference in refractive index before and after a high-temperature and high-humidity test in which the cured product is exposed to an environment of 65°C and 90% RH for 24 hours, and this difference is less than 0.002. <2> An adhesive for optical components as described in <1>, wherein the cured product has a refractive index of 1.520 to 1.570 when the high-temperature and high-humidity test has not been performed. <3> An adhesive for optical components as described in <1>, wherein the cured product has a refractive index of 1.540 to 1.555 when the high-temperature and high-humidity test has not been performed. <4> An adhesive for optical components as described in any one of <1> to <3>, wherein the yellow index of the cured product after the high-temperature and high-humidity test is less than twice that of the product before the high-temperature and high-humidity test. <5> An adhesive for optical components as described in any one of <1> to <4>, which contains multiple types of antioxidants. <6> The adhesive for optical components according to <5>, wherein when the total amount of the alicyclic epoxy compound and the oxetanyl group-containing compound is 100 parts by mass, each of the multiple types of antioxidants is contained in less than 5.00 parts by mass. <7> The adhesive for optical components according to <5>, wherein when the total amount of the alicyclic epoxy compound and the oxetanyl group-containing compound is 100 parts by mass, each of the multiple types of antioxidants is contained in less than 1.00 part by mass. <8> The adhesive for optical components according to claim 1, wherein the content of the hindered amine-based light stabilizer is 1 part by mass or less. <9> The adhesive for optical components according to any one of <1> to <8>, wherein the antioxidant comprises a phenol-based antioxidant and a thioether-based antioxidant. <10> An optical element comprising a first optical component, an adhesive layer, and a second optical component in this order, wherein the adhesive layer contains a cured product of the adhesive for optical components according to any one of <1> to <9>. <11> The optical element according to <10>, wherein the adhesive layer has an absolute value of the difference in refractive index between at least one of the refractive indices of the first optical element and the second optical element of 0.005 or less. <12> The optical element according to <10> or <11>, which is a lens. <13> The optical element according to <12>, which is a lens for a virtual reality device, a mixed reality device, an augmented reality device, a cross-reality device, or a head-mounted display. <14> The optical element according to any one of <10> to <12>, which is for AR glasses.<15> An optical instrument including an optical element, wherein the optical element comprises a first optical member, an adhesive layer, and a second optical member in that order, and the adhesive layer includes a cured product of an adhesive for optical members containing an alicyclic epoxy compound, an oxetanyl group-containing compound, a hindered amine-based light stabilizer, and an antioxidant, and the cured product of the adhesive for optical members, which is 100 μm thick and prepared by irradiating the adhesive for optical members with light of a wavelength of 365 nm at an energy density of 3000 mJ / cm2, has an absolute value of the difference in refractive index less than 0.002 before and after a high temperature and high humidity test in which the cured product is exposed to an environment of 65°C and 90% RH for 24 hours, the optical instrument.

[0008] According to one embodiment of the present disclosure, an adhesive for optical components in which changes in optical properties are suppressed is provided. Furthermore, according to one embodiment of the present disclosure, an optical element and an optical device in which changes in optical properties are suppressed are provided.

[0009] The following describes in detail an adhesive for optical components, an optical element, and an optical device, which are embodiments of this disclosure. The descriptions of requirements below may be based on typical embodiments of this disclosure, but this disclosure is not limited to such embodiments and may be implemented with appropriate modifications within the scope of the purpose of this disclosure.

[0010] In this disclosure, numerical ranges indicated using "~" mean ranges that include the numerical values ​​before and after "~" as the lower and upper limits, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this disclosure, the amount of each component in a composition means the total amount of multiple substances present in the composition if there are multiple substances corresponding to each component in the composition, unless otherwise specified. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, "mass%" and "weight%" are synonymous, and "parts by mass" and "parts by weight" are synonymous.

[0011] <Adhesive for Optical Components> An adhesive for optical components (hereinafter also referred to as "adhesive for optical components") according to one embodiment of the present disclosure comprises an alicyclic epoxy compound, an oxetanyl group-containing compound, a hindered amine-based light stabilizer, and an antioxidant. When light with a wavelength of 365 nm is applied to the adhesive for optical components at an energy density of 3000 mJ / cm², the adhesive for optical components is subjected to light with a wavelength of 365 nm. ２ A cured product of an optical component adhesive with a thickness of 100 μm, prepared by irradiation, shows that the absolute difference in refractive index before and after a high-temperature and high-humidity test in which the cured product is exposed to an environment of 65°C and 90% RH for 24 hours is less than 0.002.

[0012] For example, current AR glasses use an optical component called a waveguide to propagate light output from a display engine using total internal reflection, and project an image onto the AR glasses. A person wearing AR glasses can see the projected image along with the real world seen through the AR glasses. Waveguides for AR glasses have been developed to have a laminated structure in which optical components made of glass or transparent optical resin are bonded together with an adhesive for optical components. By matching the refractive index of the optical component with the refractive index of the cured adhesive for optical components, reflection of light at the interface between the optical component and the cured adhesive for optical components can be suppressed, enabling efficient light propagation. However, the cured adhesive for optical components sometimes had problems maintaining its refractive index, for example, due to changes over time.

[0013] The inventors investigated the composition of adhesives for optical components in order to improve the refractive index retention of cured products of adhesives for optical components, focusing on the relationships between each component. They found that when an adhesive for optical components containing an alicyclic epoxy compound, an oxetanyl group-containing compound, a hindered amine-based light stabilizer, and an antioxidant was used in a specific high-temperature, high-humidity test on cured products of the adhesive for optical components, the absolute value of the difference in refractive index before and after the test was less than 0.002. This suppressed not only the change in refractive index but also the change in color, thus suppressing the change in optical properties.

[0014] Although the mechanism by which the above effect is achieved is not clear, it is presumed that the various components of the adhesive for optical components act synergistically, resulting in an adhesive for optical components in which changes in the optical properties of the cured product are suppressed.

[0015] (Alicyclic epoxy compounds) In this specification, alicyclic epoxy compounds refer to compounds having an epoxy group and an alicyclic structure that can be photocured by the action of a photopolymerization initiator described later. The adhesive for optical components may contain only one type of alicyclic epoxy compound, or it may contain two or more types.

[0016] Adhesives for optical components tend to exhibit better visible light transmittance in their cured products when they contain alicyclic epoxy compounds. While alicyclic epoxy compounds may contain structures other than epoxy groups and alicyclic structures within their molecules, it is preferable that they do not contain aromatic rings to prevent discoloration of the cured product.

[0017] The number of epoxy groups contained in the alicyclic epoxy compound may be one or more, but preferably two to ten, and more preferably two to five. When the number of epoxy groups is two or more, the alicyclic epoxy compound becomes easier to photocur. On the other hand, when the number of epoxy groups exceeds ten, depending on the curing conditions, the curing of the adhesive for optical components may proceed excessively in some areas, and unreacted components of the adhesive for optical components may remain, resulting in a low curing rate. Furthermore, the number of alicyclic structures in the alicyclic epoxy compound is not particularly limited; it may be just one, or it may be two or more.

[0018] Examples of alicyclic epoxy compounds include compounds having an epoxycyclo structure represented by the following general formula (A). An epoxycyclo structure is a structure obtained by epoxidizing a cycloalkene with an oxidizing agent such as a peroxide, and has an aliphatic ring and an epoxy group composed of two carbon atoms and an oxygen atom that make up the aliphatic ring.

[0019]

[0020] In the above general formula (A), M represents an aliphatic ring (alicyclic structure). The number of carbon atoms in the aliphatic ring is preferably 4 to 8, more preferably 5 to 6. When the number of carbon atoms in the aliphatic ring of the epoxy cyclo structure is within this range, the viscosity of the adhesive for optical members is more likely to fall within the desired range.

[0021] In addition, when synthesizing an alicyclic epoxy compound having an epoxy cyclo structure, it is not necessary to use a compound containing a halogen such as chlorine. Therefore, the alicyclic epoxy compound is preferable in that it is less likely to contain halogen ions such as chlorine compared to other epoxy compounds.

[0022] Specific examples of the above epoxy cyclo structure include epoxy cyclohexane, epoxy cyclopentane, etc., and epoxy cyclohexane is preferred.

[0023] Here, the number of epoxy cyclo structures in the alicyclic epoxy compound is not particularly limited, and it may be only one or two or more. Examples of alicyclic epoxy compounds containing only one epoxy cyclo structure include compounds represented by the following general formula (A-1).

[0024]

[0025] M in the above general formula (A-1) １ represents an aliphatic ring (alicyclic structure), and the number of its carbon atoms is preferably 4 to 8, more preferably 5 to 6. Substituents such as halogen atoms, alkyl groups, fluoroalkyl groups, aryl groups, furyl groups, thienyl groups, etc. may be bonded to the alicyclic structure represented by M １ .

[0026] Examples of halogen atoms bonded to the alicyclic structure include fluorine and the like. Examples of alkyl groups bonded to the alicyclic structure include linear or branched alkyl groups having 1 to 6 carbon atoms (such as methyl group, ethyl group, propyl group, butyl group, pentyl group, and hexyl group). Examples of fluoroalkyl groups bonded to the alicyclic structure include linear or branched fluoroalkyl groups having 1 to 6 carbon atoms (such as perfluoromethyl group, perfluoroethyl group, and perfluoropropyl group). Examples of aryl groups bonded to the alicyclic structure include aryl groups having 6 to 18 carbon atoms (such as phenyl group and naphthyl group).

[0027] Also, X in the general formula (A-1) １ is a single bond or a linking group. Examples of the linking group include a divalent hydrocarbon group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a carbonate bond, an amide bond, or a group in which a plurality of these are linked.

[0028] Examples of the divalent hydrocarbon group include an alkylene group having 1 to 18 carbon atoms or a divalent alicyclic hydrocarbon group. Examples of the alkylene group having 1 to 18 carbon atoms include methylene group, methylmethylene group, dimethylmethylene group, ethylene group, propylene group, and trimethylene group. Examples of the divalent alicyclic hydrocarbon group include divalent cycloalkylene groups (including cycloalkylidene groups) such as 1,2-cyclopentylene group, 1,3-cyclopentylene group, cyclopentylidene group, 1,2-cyclohexylene group, 1,3-cyclohexylene group, 1,4-cyclohexylene group, and cyclohexylidene group. X in the general formula (A-1) １ is preferably a single bond.

[0029] Examples of the alicyclic compound represented by the general formula (A-1) include compounds represented by the following chemical formulas (A-1a) and (A-1b).

[0030]

[0031] On the other hand, examples of the alicyclic epoxy compound containing two epoxycyclic structures include compounds represented by the following general formula (A-2).

[0032]

[0033] M in the general formula (A-2) above ２ and M ３ represent an alicyclic structure (aliphatic ring), and the number of carbon atoms in the alicyclic structure is preferably 4 to 8, more preferably 5 to 6. Each of the alicyclic structures may independently have a substituent such as a halogen atom, an alkyl group, a fluoroalkyl group, an aryl group, a furyl group, or a thienyl group bonded thereto. Specific examples of these are the same as the substituents bonded to the alicyclic structure of the compound represented by the general formula (A-1) above.

[0034] X in the general formula (A-2) above ２ is a single bond or a linking group. Examples of the linking group include a divalent hydrocarbon group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a carbonate bond, an amide bond, or a group in which a plurality of these are linked, and are the same as the linking group represented by X １ in the general formula (A-1) above.

[0035] Specific examples of the alicyclic epoxy compound represented by the general formula (A-2) above include 1,2-bis(3,4-epoxycyclohexan-1-yl)ethane, 2,2-bis(3,4-epoxycyclohexan-1-yl)propane, ε-caprolactone-modified 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, and a compound represented by the following structural formula. In the following structural formula, l is an integer of 1 to 10, and m is an integer of 1 to 30. Also, R is an alkylene group having 1 to 8 carbon atoms (preferably an alkylene group having 1 to 3 carbon atoms such as a methylene group, an ethylene group, a propylene group, or an isopropylene group).

[0036] [

[0037] Specific examples of the alicyclic epoxy compound containing three epoxycyclo structures include a compound represented by the following general formula. In the general formula, n1 and n2 are each an integer of 1 to 30.

[0038]

[0039] Furthermore, examples of epoxy compounds containing an epoxycyclo structure include compounds represented by the following general formula (A-3).

[0040]

[0041] In the above general formula (A-3), M ４ and M ５ The ∫ represents an alicyclic structure (aliphatic ring), and the number of carbon atoms in the alicyclic structure is preferably 4 to 8, and more preferably 5 to 6. The alicyclic structure may independently have substituents such as halogen atoms, alkyl groups, fluoroalkyl groups, aryl groups, furyl groups, and thienyl groups attached to it. These specific examples are similar to the substituents attached to the alicyclic structure of the compound represented by the general formula (A-1) described above.

[0042] Specific examples of compounds represented by the above general formula (A-3) include 3,4:7,8-diepoxybicyclo[4.3.0]nonane, etc.

[0043] Furthermore, other examples of alicyclic epoxy compounds include compounds having a glycidyl ether group. Examples of alicyclic compounds having a glycidyl ether group include hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, and their alkylene oxide adducts.

[0044] Among the alicyclic epoxy compounds mentioned above, 3',4'-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate is particularly preferred in terms of viscosity, reactivity, and transparency.

[0045] In all alicyclic epoxy compounds of any structure, the weight-average molecular weight is preferably 200 or higher from the viewpoint of the strength of the resulting cured product. On the other hand, the weight-average molecular weight is preferably 1000 or lower, and more preferably 500 or lower, from the viewpoint of setting the viscosity of the adhesive for optical components within a desired range. The weight-average molecular weight (Mw) is the styrene equivalent value determined by gel permeation chromatography (GPC).

[0046] Furthermore, while the epoxy equivalent of the alicyclic epoxy compound is not particularly limited, it is preferably 90 g / eq to 250 g / eq, and more preferably 100 g / eq to 190 g / eq. When the epoxy equivalent of the alicyclic epoxy compound is within this range, good photocurability tends to be achieved. In addition, the curing shrinkage of the adhesive for optical components can be kept within an appropriate range. The epoxy equivalent of the alicyclic epoxy compound can be measured in accordance with JIS K7236:2001.

[0047] The amount of alicyclic epoxy compound in the adhesive for optical components is appropriately selected depending on the application of the adhesive, but is preferably 10% to 40% by mass, more preferably 12% to 35% by mass, and even more preferably 15% to 30% by mass. When the amount of alicyclic epoxy compound is within this range, the photocurability of the adhesive for optical components tends to be even better.

[0048] Furthermore, when the total amount of the alicyclic epoxy compound and the oxetanyl group-containing compound described later is 100 parts by mass, the amount of the alicyclic epoxy compound is preferably 30 parts by mass or more and 70 parts by mass or less, more preferably 32 parts by mass or more and 65 parts by mass or less, and even more preferably 33 parts by mass or more and 60 parts by mass or less. When the content ratio of the alicyclic epoxy compound to the oxetanyl group-containing compound is within this range, good photocurability tends to be obtained.

[0049] (Oxetanyl Group-Containing Compounds) In this specification, an oxetanyl group-containing compound is a compound having at least one oxetanyl group in its molecule and being photocurable by the action of a photopolymerization initiator described later. The number of oxetanyl groups in the oxetanyl group-containing compound is preferably 1 to 5, but from the viewpoint of photocurability, the number of oxetanyl groups is more preferably 2 or more, and particularly preferably 2. The adhesive for optical components may contain only one type of oxetanyl group-containing compound, or it may contain two or more types.

[0050] Examples of oxetanyl group-containing compounds having only one oxetanyl group include 2-ethylhexyloxetane, 3-ethyl-3-hydroxymethyloxetane, 3-(meth)allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanylmethoxy)methylbenzene, 2-ethylhexyl(3-ethyl-3-oxetanylmethyl) ether, ethyldiethylene glycol(3-ethyl-3-oxetanylmethyl) ether, and 3-cyclohexylmethyl-3-ethyl-oxetane. Among these, 2-ethylhexyloxetane (for example, Aronoxetane OXT-212, manufactured by Toagosei Chemical Co., Ltd.) is preferred from the viewpoint of availability and other factors.

[0051] Examples of oxetanyl group-containing compounds having two oxetanyl groups include 1,4-bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxy]benzene, 1,3-bis[(3-ethyl-3-oxetanyl)methoxy]benzene, and 3,7-bis(3-oxetanyl)- These include 5-oxanonanes, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycol bis(3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyl bis(3-ethyl-3-oxetanylmethyl) ether, etc. Among these, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (for example, Aronoxetane OXT-221, manufactured by Toagosei Chemical Co., Ltd.) is preferred from the viewpoint of availability and other factors.

[0052] Examples of oxetanyl group-containing compounds having three or more oxetanyl groups include trimethylolpropane tris(3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tris(3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetrakis(3-ethyl-3-oxetanylmethyl) ether, and dipentaerythritol pentakis(3-ethyl-3-oxetanylmethyl) ether.

[0053] The content of oxetanyl group-containing compounds in adhesives for optical components is appropriately selected depending on the application of the adhesive for optical components, but from the viewpoint of suppressing changes in the optical properties of the cured product of the adhesive for optical components, it is preferably 10% by mass or more and 45% by mass or less, more preferably 12% by mass or more and 43% by mass or less, and even more preferably 15% by mass or more and 40% by mass or less. When the amount of oxetanyl group-containing compounds is within this range, the curing speed of the adhesive for optical components tends to be appropriate and the photocurability tends to be good.

[0054] Furthermore, when the total amount of the alicyclic epoxy compound and the oxetanyl group-containing compound described later is 100 parts by mass, the content of the oxetanyl group-containing compound is preferably 75 parts by mass or less, preferably 70 parts by mass or less, and more preferably 50 parts by mass or less. When the amount of the oxetanyl group-containing compound is within this range, the storage stability of the adhesive for optical components tends to be further enhanced, and uneven curing tends to occur less easily.

[0055] (Hindered Amine Light Stabilizers) An adhesive for optical components according to one embodiment of the present disclosure may contain only one type of hindered amine light stabilizer (HALS), or it may contain two or more types. From the viewpoint of suppressing changes in the optical properties of the cured product of the adhesive for optical components, the following compounds can be specifically listed as hindered amine light stabilizers included in the adhesive for optical components according to one embodiment of the present disclosure. In other words, examples of hindered amine-based light stabilizers include bis(1,2,2,6,6-pentamethyl-4-piperidine) sebacate, 1-(1,2,2,6,6-pentamethyl-4-piperidinyl)10-methyl sebacate, bis(1-undecanoxy-2,2,6,6-tetramethyl-4-piperidine) carbonate, bis(2,2,6,6-tetramethyl-1-piperidine-4-oxyl) sebacate, 2,2,6,6-tetramethyl-4-piperidine hexadecanoate, and 2,2,6,6-tetramethyl-4-piperidine octadecanoate. In particular, from the viewpoint of suppressing changes in the optical properties of the cured product of the adhesive for optical components, bis(1,2,2,6,6-pentamethyl-4-piperidine) sebacate, bis(1-undecanoxy-2,2,6,6-tetramethyl-4-piperidine) carbonate, 2,2,6,6-tetramethyl-4-piperidine hexadecanoate, or 2,2,6,6-tetramethyl-4-piperidine octadecanoate are preferred.

[0056] As commercially available hindered amine-based light stabilizers used in adhesives for optical components according to one embodiment of this disclosure, any of the Tinuvin series (all manufactured by BASF) can be preferred. As hindered amine-based light stabilizers, it is preferable to use non-basic hindered amine-based light stabilizers from the viewpoint of suppressing changes in the optical properties of the cured product of the adhesive for optical components under acidic conditions, etc. As commercially available non-basic hindered amine-based light stabilizers, Tinuvin 123, Tinuvin 249, etc. (all manufactured by BASF) from the Tinuvin series can be preferred.

[0057] From the viewpoint of suppressing changes in the optical properties of the cured product of the adhesive for optical components, the content of the hindered amine-based light stabilizer in the adhesive for optical components is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 1 part by mass, when the total amount of epoxy compounds and oxetanyl group-containing compounds is 100 parts by mass.

[0058] In this specification, in the total amount of epoxy compounds and oxetanyl group-containing compounds, the amount of epoxy compounds is the sum of the total amount of alicyclic epoxy compounds and the total amount of other epoxy compounds described below. If an alicyclic epoxy compound contains multiple compounds, the total amount of alicyclic epoxy compounds is the total amount of all compounds contained in the alicyclic epoxy compound, and if other epoxy compounds contain multiple compounds, the total amount of other epoxy compounds is the total amount of all compounds contained in the other epoxy compound.

[0059] Hindered amine-based light stabilizers are thought to have several active species acting in a synergistic manner, and although not entirely clear, it is presumed that they suppress changes in the optical properties of cured adhesives for optical components by interacting with antioxidants. Therefore, from the viewpoint of suppressing changes in the optical properties of cured adhesives for optical components, if the adhesive contains one type of antioxidant, it is preferable to include 0.1 to 1.1 parts by mass of hindered amine-based light stabilizers based on the content of this antioxidant. If the adhesive contains multiple types of antioxidants, it is preferable to include 0.1 to 1.1 parts by mass of hindered amine-based light stabilizers based on the content of at least one of the multiple types of antioxidants.

[0060] (Antioxidants) An adhesive for optical components according to one embodiment of the present disclosure may contain only one type of antioxidant, or it may contain two or more types. From the viewpoint of suppressing changes in the optical properties of the cured product of the adhesive for optical components, it is preferable that the adhesive contains multiple types of antioxidants. Specifically, phenolic antioxidants and thioether-based antioxidants are preferred as antioxidants.

[0061] In one embodiment of the present disclosure, the adhesive for optical components preferably contains at least both a phenolic antioxidant and a thioether-based antioxidant as antioxidants, from the viewpoint of suppressing changes in the optical properties of the cured product of the adhesive for optical components. Although not evident, it is presumed that by including both a phenolic antioxidant and a thioether-based antioxidant, the thioether-based antioxidant has the effect of stabilizing the phenolic antioxidant. In addition, one or more types of antioxidants other than phenolic antioxidants and thioether-based antioxidants may be included, as long as they do not hinder the effect of the adhesive for optical components in one embodiment of the present disclosure on suppressing changes in the optical properties of the cured product of the adhesive for optical components.

[0062] As the phenolic antioxidant contained in the adhesive for optical components according to one embodiment of this disclosure, conventionally known phenolic antioxidants used with epoxy compounds can be used. Phenolic antioxidants having bulky alkyl groups such as tert-butyl groups, and hindered phenolic antioxidants having sterically hindered phenolic groups are preferred from the viewpoint of having structural stability and suppressing changes in the optical properties of the cured product of the adhesive for optical components.

[0063] Specific examples of phenolic antioxidants included in an adhesive for optical components according to one embodiment of the present disclosure include 2,6-di-tert-butylmethylphenol, 2,4,6-tri-tert-butylphenol, tris(2,4-di-tert-butylphenyl) phosphite, tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane, and the like.

[0064] The phenolic antioxidant included in the adhesive for optical components according to one embodiment of the present disclosure is preferably a commercially available product such as Irganox 1010, Irganox B225 (both manufactured by BASF), or AO-60 (manufactured by ADEKA).

[0065] As the thioether-based antioxidant included in the adhesive for optical components according to one embodiment of the present disclosure, a thioether-based antioxidant conventionally used with epoxy compounds can be used. From the viewpoint of suppressing volatility, a thioether-based antioxidant having a long-chain alkyl group, and from the viewpoint of antioxidant effect, a thioether-based antioxidant with a high sulfur content are preferred.

[0066] Specific examples of thioether-based antioxidants included in an adhesive for optical components according to one embodiment of the present disclosure include dilauryl thiodipropionate, distearyl thiodipropionate, and pentaerythritol tetrakis(3-dodecylthiopropionate).

[0067] The thioether-based antioxidant included in the adhesive for optical components according to one embodiment of the present disclosure is preferably commercially available, such as AO-503 or AO-412S (both manufactured by ADEKA Corporation).

[0068] From the viewpoint of suppressing changes in the optical properties of the cured product of the adhesive for optical components, the content of the antioxidant in the adhesive for optical components is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 1 part by mass, when the total amount of epoxy compounds and oxetanyl group-containing compounds is 100 parts by mass.

[0069] From the viewpoint of suppressing changes in the optical properties of the cured product of the adhesive for optical components, when the total amount of epoxy compounds and oxetanyl group-containing compounds is 100 parts by mass, it is preferable that each of the multiple types of antioxidants is included in an amount of less than 5.00 parts by mass, and more preferably less than 1.00 part by mass.

[0070] (Photopolymerization Initiator) An adhesive for optical components according to one embodiment of the present disclosure includes a photopolymerization initiator. The type of photopolymerization initiator is not particularly limited as long as it is a compound that is activated by light irradiation and capable of curing the above-mentioned alicyclic epoxy compounds or oxetanyl group-containing compounds. The adhesive for optical components may contain only one type of photopolymerization initiator or two or more types. From the viewpoint of curability, it is preferable to use a photocationic polymerization initiator that has a maximum absorption wavelength in the range of 270 nm or more and less than 400 nm.

[0071] Examples of photopolymerization initiators include cationic polymerization initiators (photoacid generators) that generate acid upon light irradiation. The cation of the cationic polymerization initiator can be any monovalent cation, and may include oxonium ions, ammonium ions, sulfonium ions, or iodonium ions.

[0072] Examples of oxonium ions include oxonium ions such as trimethyloxonium, diethylmethyloxonium, triethyloxonium, and tetramethylenemethyloxonium; pyrinium ions such as 4-methylpyrilinium, 2,4,6-trimethylpyrilinium, 2,6-di-tert-butylpyrilinium, and 2,6-diphenylpyrilinium; and chromium and isochromenium ions such as 2,4-dimethylchromium and 1,3-dimethylisochromenium.

[0073] Examples of ammonium ions include pyrrolidinium ions such as N,N-dimethylpyrrolidinium, N-ethyl-N-methylpyrrolidinium, and N,N-diethylpyrrolidinium; imidazolinium ions such as N,N'-dimethylimidazolinium, N,N'-diethylimidazolinium, N-ethyl-N'-methylimidazolinium, 1,3,4-trimethylimidazolinium, and 1,2,3,4-tetramethylimidazolinium; tetrahydropyrimidinium ions such as N,N'-dimethyltetrahydropyrimidinium; morpholinium ions such as N,N'-dimethylmorpholinium; N This includes piperidinium ions such as N'-diethylpiperidinium; pyridinium ions such as N-methylpyridinium, N-benzylpyridinium, and N-phenacylpyridinium; imidazolium ions such as N,N'-dimethylimidazolium; quinorium ions such as N-methylquinorium, N-benzylquinorium, and N-phenacylquinorium; isoquinorium ions such as N-methylisoquinorium; thiazonium ions such as benzylbenzothiazonium and phenacylbenzothiazonium; and acridium ions such as benzylacridium and phenacylacridium.

[0074] Examples of phosphonium ions include tetraarylphosphonium ions such as tetraphenylphosphonium, tetra-p-tolylphosphonium, tetrakis(2-methoxyphenyl)phosphonium, tetrakis(3-methoxyphenyl)phosphonium, and tetrakis(4-methoxyphenyl)phosphonium; triarylphosphonium ions such as triphenylbenzylphosphonium, triphenylphenacylphosphonium, triphenylmethylphosphonium, and triphenylbutylphosphonium; and tetraalkylphosphonium ions such as triethylbenzylphosphonium, tributylbenzylphosphonium, tetraethylphosphonium, tetrabutylphosphonium, tetrahexylphosphonium, triethylphenacylphosphonium, and tributylphenacylphosphonium.

[0075] Examples of sulfonium ions include triphenylsulfonium, tri-p-tolylsulfonium, tri-o-tolylsulfonium, tris(4-methoxyphenyl)sulfonium, 1-naphthyldiphenylsulfonium, 2-naphthyldiphenylsulfonium, tris(4-fluorophenyl)sulfonium, tri-1-naphthylsulfonium, tri-2-naphthylsulfonium, tris(4-hydroxyphenyl)sulfonium, 4-(phenylthio)phenyldiphenylsulfonium, 4-(p-tolylthio)phenyldi-p-tolylsulfonium, 4-(4-methoxyphenylthio)phenylbis(4-methoxyphenyl)sulfonium, 4-(phenylthio)phenylbis(4-fluorophenyl)sulfonium, 4-(phenylthio)phenylbis(4-methoxyphenyl)sulfonium, 4-(phenylthio)phenyldi-p-tolylsulfonium, [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium, [4-(2-thiooxantylthio] )phenyl]diphenylsulfonium, bis[4-(diphenylsulfonio)phenyl]sulfide, bis[4-{bis[4-(2-hydroxyethoxy)phenyl]sulfonio}phenyl]sulfide, bis{4-[bis(4-fluorophenyl)sulfonio]phenyl}sulfide, bis{4-[bis(4-methylphenyl)sulfonio]phenyl}sulfide, bis{4-[bis(4-methoxyphenyl)sulfonio]phenyl}sulfide, 4-(4-benzoyl-2-chlorophenic Luthio)phenylbis(4-fluorophenyl)sulfonium, 4-(4-benzoyl-2-chlorophenylthio)phenyldiphenylsulfonium, 4-(4-benzoylphenylthio)phenylbis(4-fluorophenyl)sulfonium, 4-(4-benzoylphenylthio)phenyldiphenylsulfonium, 7-isopropyl-9-oxo-10-thia-9,10-dihydroanthracene-2-yldi-p-tolylsulfonium, 7-isopropyl-9-oxo-10-thia-9,10-dihydroanthracene-2-yldiphenylsulfonium, 2-[(di-p-tolyl)sulfonio]thioxanthone, 2-[(diphenyl)sulfonio]thioxanthone, 4-(9-oxo-9H-thioxanthene-2-yl)thiophenyl-9-oxo-9H-thioxanthene-2-ylphenylsulfonium, 4-[4-(4-tert-butylbenzoyl)phenylthio]phenyldi-p-tolylsulfonium, 4-[4-( 4-tert-butylbenzoyl)phenylthio]phenyldiphenylsulfonium, 4-[4-(benzoylphenylthio)]phenyldi-p-tolylsulfonium, 4-[4-(benzoylphenylthio)]phenyldiphenylsulfonium, 5-(4-methoxyphenyl)thioanthurenium, 5-phenylthioanthurenium, 5-tolylthioanthurenium, 5-(4-ethoxyphenyl)thioanthurenium, 5-(2,4,Triarylsulfonium ions such as 6-trimethylphenyl)thioanthrenium; diarylsulfonium ions such as diphenylphenacylsulfonium, diphenyl-4-nitrophenacylsulfonium, diphenylbenzylsulfonium, and diphenylmethylsulfonium; phenylmethylbenzylsulfonium, 4-hydroxyphenylmethylbenzylsulfonium, 4-methoxyphenylmethylbenzylsulfonium, 4-acetocarbonyloxyphenylmethylbenzylsulfonium, 4-hydroxyphenyl(2-naphthylmethyl)methylsulfonium, 2-naphthylmethylbenzylsulfonium, 2-naphthylmethyl(1-ethoxycarbonyl)ethylsulfonium This includes monoarylsulfonium ions such as phenylmethylphenacylsulfonium, 4-hydroxyphenylmethylphenacylsulfonium, 4-methoxyphenylmethylphenacylsulfonium, 4-acetocarbonyloxyphenylmethylphenacylsulfonium, 2-naphthylmethylphenacylsulfonium, 2-naphthyloctadecylphenacylsulfonium, and 9-anthracenylmethylphenacylsulfonium; trialkylsulfonium ions such as dimethylphenacylsulfonium, phenacyltetrahydrothiophenium, dimethylbenzylsulfonium, benzyltetrahydrothiophenium, and octadecylmethylphenacylsulfonium; and others.

[0076] Examples of iodonium ions include diphenyliodonium, di-p-tolyliodonium, bis(4-dodecylphenyl)iodonium, bis(4-methoxyphenyl)iodonium, (4-octyloxyphenyl)phenyliodonium, bis(4-decyloxy)phenyliodonium, 4-(2-hydroxytetradecyloxy)phenylphenyliodonium, 4-isopropylphenyl(p-tolyl)iodonium, and 4-isobutylphenyl(p-tolyl)iodonium.

[0077] Among the above cations, ammonium ions, phosphonium ions, sulfonium ions, or iodonium ions are more preferred, sulfonium ions or iodonium ions are even more preferred, and sulfonium ions are even more preferred. Among sulfonium ions, triarylsulfonium ions are preferred.

[0078] On the other hand, the type of counteranion that forms a salt with the cation of the cationic polymerization initiator is not particularly limited, but it is preferable that the anion includes a central atom and a ligand coordinated to the central atom. Examples of central atoms include P, As, Sb, and Ga. Examples of ligands include F － or Cl － (CF ２ CF ３ ) ｎ F （６－ｎ） This includes substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups, etc.

[0079] Examples of preferred counter-anion structures include PF ６ － (CF ２ CF ３ ) ｎ PF （６－ｎ） － AsF ６ － SbF ６ － BF ４ － SbCl ６ － , or (C ６ F ６ ) ４ B － It contains the anion.

[0080] From the viewpoint of suppressing changes in the optical properties of the cured product of the adhesive for optical components, the amount of photopolymerization initiator in the adhesive for optical components is preferably 0.01 parts by mass or more and 2.0 parts by mass or less, when the total amount of epoxy compounds and oxetanyl group-containing compounds is 100 parts by mass. Within this range, it is possible to efficiently cure oxetanyl group-containing compounds, alicyclic epoxy compounds, and other epoxy compounds.

[0081] (Other Epoxy Compounds) In addition to the alicyclic epoxy compounds described above, adhesives for optical components may also contain compounds having epoxy groups (referred to herein as "other epoxy compounds"). Other epoxy compounds are any compounds that have epoxy groups in their molecule and do not contain an alicyclic structure. For example, they may be compounds having an aromatic ring, compounds having a linear or branched structure, or compounds containing both. Adhesives for optical components may contain only one other epoxy compound, or two or more.

[0082] The other epoxy compounds may have only one epoxy group or two or more, but two or more is more preferable. Furthermore, it is preferable that the other epoxy compounds contain an ether linkage. Examples of epoxy compounds containing an ether linkage include epoxy compounds containing a glycidyl ether group and an aromatic ring.

[0083] Furthermore, other epoxy compounds include hydrogenated epoxy compounds. Hydrogenated epoxy compounds include compounds in which a glycidyl ether group is directly bonded to a non-aromatic saturated or unsaturated aliphatic cyclic hydrocarbon skeleton, or alicyclic epoxy compounds in which a glycidyl ether group is bonded to a non-aromatic saturated or unsaturated aliphatic cyclic hydrocarbon skeleton via a hydrocarbon. In other words, hydrogenated epoxy compounds may be hydrogenated products of the epoxy compounds containing the above-mentioned ether bond.

[0084] Examples of epoxy compounds containing a glycidyl ether group and an aromatic ring include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and their alkylene oxide adducts (e.g., ethylene oxide adducts, propylene oxide adducts, and so on). Among these, the propylene oxide adduct of bisphenol A diglycidyl ether is preferred. When an adhesive for optical components contains this compound, the refractive index of the cured product tends to be higher and the product tends to be more rigid.

[0085] An adhesive for optical components, which is one embodiment of the present disclosure, preferably contains all of the following epoxy compounds: alicyclic epoxy compounds, glycidyl ether-type epoxy compounds, and hydrogenated epoxy compounds, from the viewpoint of suppressing changes in the optical properties of the cured product. The adhesive may contain one or more of each of the alicyclic epoxy compounds, glycidyl ether-type epoxy compounds, and hydrogenated epoxy compounds. Furthermore, from the viewpoint of suppressing changes in the optical properties of the cured product, the alicyclic epoxy compound and other epoxy compounds are preferably polyfunctional epoxy compounds having multiple epoxy groups.

[0086] The amount of other epoxy compounds in the adhesive for optical components is preferably 10% by mass or more and 50% by mass or less, and more preferably 15% by mass or more and 30% by mass or less. When the amount of other epoxy compounds is within this range, the curing properties of the adhesive for optical components tend to be good, and furthermore, the light transmittance of the cured product tends to be good.

[0087] The content of other epoxy compounds is preferably 30 to 70 parts by mass, more preferably 32 to 65 parts by mass, and even more preferably 33 to 66 parts by mass, when the total amount of oxetanyl group-containing compounds and epoxy group-containing compounds (the above-mentioned alicyclic epoxy compounds and other epoxy compounds) is 100 parts by mass. If the other epoxy compounds include multiple types of epoxy compounds, the content of other epoxy compounds refers to the total amount of other epoxy compounds, which is the sum of the amounts of each of the multiple types of epoxy compounds.

[0088] (Other Components) The adhesive for optical components may further contain other components as needed. Examples of other components include tackifying resins, various silane coupling agents, leveling agents, defoamers, stabilizers, polymerization initiators, anti-aging agents, wettability modifiers, surfactants, plasticizers, UV absorbers, preservatives, and antibacterial agents. The adhesive for optical components may contain only one of these, or two or more.

[0089] (Method for preparing adhesive for optical components) The method for preparing adhesive for optical components is not particularly limited, and all components may be mixed at once, or they may be mixed in two or more separate steps. For example, alicyclic epoxy compounds, oxetanyl group-containing compounds, and other epoxy compounds may be mixed first, and then other components (e.g., hindered amine-based light stabilizers, antioxidants, photopolymerization initiators, additives, etc.) may be further mixed. Heating may be performed during mixing as necessary. The heating temperature is appropriately selected depending on the type of alicyclic epoxy compound, softening point, etc., but is preferably 80°C to 150°C, and more preferably 100°C to 140°C. Furthermore, the heating time is also appropriately selected, usually preferably 30 minutes to 120 minutes, and more preferably 40 minutes to 80 minutes.

[0090] (Physical Properties of Adhesives for Optical Components) As a physical property of an adhesive for optical components according to one embodiment of the present disclosure, the viscosity is appropriately selected according to the application of the adhesive for optical components, but for example, the viscosity measured at 23°C with an R-type viscometer is preferably 100 mPa·s or more and 100,000 mPa·s or less, and more preferably 300 mPa·s or more and 7,000 mPa·s or less. When the viscosity of the adhesive for optical components is within this range, the adhesive for optical components can easily penetrate into the uneven parts when used to bond optical components having uneven parts on the bonding surface. In addition, the adhesive for optical components can be easily applied by various coating devices.

[0091] As for the physical properties of the adhesive for optical components, which is one embodiment of the present disclosure, the curing conditions are appropriately selected according to the type of photopolymerization initiator, etc., but can usually be cured by irradiation with ultraviolet light or visible light, and it is preferable to cure by irradiation with light of a wavelength of 365 nm to 425 nm. The integrated light amount at this time is preferably 1000 J to 5000 J, and more preferably 2000 J to 5000 J. When the adhesive for optical components is cured under these conditions, a sufficiently cured product can be obtained.

[0092] Furthermore, when curing the adhesive for optical components, heating may be performed in conjunction with the light irradiation described above. The heating conditions are not particularly limited, but the heating temperature is usually preferably 40°C to 110°C, and more preferably 60°C to 90°C. The heating time is usually 10 minutes to 120 minutes.

[0093] The optical properties of an adhesive for optical components, which is one embodiment of the present disclosure, are as follows. Specifically, the refractive index of the cured product produced by curing under the following measurement curing conditions is preferably in the range of 1.520 to 1.575, preferably 1.530 to 1.570, more preferably in the range of 1.540 to 1.555, and even more preferably in the range of 1.542 to 1.550. Here, the cured product to be measured is the adhesive for optical components exposed to light with a wavelength of 365 nm at an energy density of 3000 mJ / cm². ２ This is a cured product of an adhesive for optical components with a thickness of 100 μm, prepared by irradiation with [specified method]. In this specification, the refractive index of the cured product of the adhesive for optical components is the value measured by a multi-wavelength Abbe refractometer.

[0094] As a physical property of an adhesive for optical components, which is one embodiment of the present disclosure, the refractive index of a cured product prepared by curing under the above-described measurement curing conditions before and after the following high-temperature and high-humidity test is as follows. That is, when the high-temperature and high-humidity test has not been performed on the cured product, i.e., before the high-temperature and high-humidity test, the absolute value of the difference in refractive index between the refractive index of the cured product and the refractive index of the cured product after the high-temperature and high-humidity test is less than 0.002, preferably 0.001 or less, and more preferably 0 within the measurable range. Here, the high-temperature and high-humidity test is a test in which the cured product is exposed to an environment of 65°C and 90% RH for 24 hours.

[0095] As a physical property of an adhesive for optical components according to one embodiment of this disclosure, the Yellowness Index (YI) of a cured product prepared by curing under the above-described measurement curing conditions, before and after the above-described high-temperature and high-humidity test, is as follows. That is, when the high-temperature and high-humidity test is not performed on the cured product, i.e., the ratio of the change in the Yellowness Index of the cured product after the high-temperature and high-humidity test is preferably less than twice, and more preferably 1.5 times or less, relative to the value before the high-temperature and high-humidity test. In this specification, the Yellowness Index of the cured product of the adhesive for optical components is a value measured by an ultraviolet-visible spectrophotometer.

[0096] One embodiment of the optical component adhesive described herein comprises an alicyclic epoxy compound, an oxetanyl group-containing compound, a hindered amine-based light stabilizer, and an antioxidant. The cured product of the optical component adhesive exhibits a cured product with an absolute difference in refractive index of less than 0.002 before and after the specific high-temperature and high-humidity test described above, and shows almost no change. As a result, not only is the change in refractive index suppressed in the cured product of the optical component adhesive, but the change in color is also suppressed, thereby suppressing changes in optical properties. The optical properties of the optical component adhesive, such as the refractive index and color of the cured product, include changes due to time, heat, humidity, and various environmental stresses such as high temperature and high humidity. According to the high-temperature and high-humidity test described above, by accelerating these environmental stresses and applying them to the cured product, it is possible to evaluate the changes in the product due to environmental stress.

[0097] The cured product of the adhesive for optical components, which is one embodiment of the present disclosure, preferably has excellent light transmittance. Specifically, the average value of the parallel light transmittance of the cured product of the adhesive for optical components with a thickness of 100 μm at wavelengths of 380 nm to 780 nm is preferably 90% or more, more preferably 93% or more, and even more preferably 95% or more. When the parallel light transmittance of the adhesive for cured components is 90% or more, it is less likely to affect the performance of the optical element and is easy to use in various applications. The above parallel light transmittance is a value measured by an ultraviolet-visible spectrophotometer.

[0098] In one embodiment of the adhesive for optical components described herein, the haze of a cured product with a thickness of 1 mm is preferably 7.0% or less, more preferably 6.0% or less, even more preferably 5.0% or less, and particularly preferably 3.0% or less. When the haze is within this range, the adhesive for optical components and its cured product become difficult to see. In this specification, haze is a value measured with a haze meter.

[0099] (Applications of the adhesive for optical components) The applications of the adhesive for optical components, which is one embodiment of the present disclosure, are not particularly limited and can be used to bond optical components of various optical elements together or to bond optical components to other components. As described above, since the adhesive for optical components is an adhesive for optical components in which changes in optical properties are suppressed, changes over time such as refractive index and yellowing can be kept to a minimum. Therefore, it is useful in parts where it is necessary to suppress changes in optical properties. For example, by using it to bond transparent optical resin in the geometric waveguide of AR glasses, the adhesive for optical components, which is one embodiment of the present disclosure and whose refractive index is matched to that of the transparent optical resin, does not change over time such as refractive index and yellowing, and thus the function of the AR glasses can be kept in good condition.

[0100] An adhesive for optical components, as described in one embodiment of this disclosure, is used for bonding polyolefins, various resins such as polycarbonate, and various metals, and the cured product is a transparent adhesive with suppressed changes in optical properties. Therefore, it can be used in a wide range of applications. For example, it is useful in the following applications: optical instruments, displays, sensors, medical devices, smartphones, etc.

[0101] As an example of optical equipment, it can be used in microscopes to bond lenses, cover glass, prisms, etc., thereby improving the precision of the optical system. For lenses, from the viewpoint of stability of optical properties, it is preferable to use it for virtual reality devices, mixed reality devices, augmented reality devices, cross-reality devices, or head-mounted displays. It can also be used in telescopes to bond lenses, lens barrels, prisms, etc., and is suitable for optical systems requiring high transmittance and high environmental resistance. Furthermore, it can contribute to miniaturization and performance improvement when used in cameras to bond lenses, image sensors, optical filters, etc. As an example of displays, it can contribute to higher brightness and longer lifespan when used in organic EL displays to bond substrates, light-emitting layers, protective films, etc. Furthermore, it can contribute to higher contrast and wider viewing angles when used in liquid crystal displays to bond liquid crystal cells, polarizing plates, backlight units, etc. As an example of sensors, it can contribute to higher sensitivity and miniaturization when used in optical sensors to bond optical fibers, sensor chips, optical lenses, sensor elements, etc. In medical devices, for example, it can be used to bond lenses, optical fibers, and image sensors in endoscopes, contributing to higher resolution and miniaturization. In smartphones, for example, it can be used to bond camera lenses, image sensors, displays, and touch panels, contributing to thinner designs and enhanced functionality.

[0102] <Optical Elements and Optical Devices> The following describes optical elements using the above-described adhesive for optical elements, but the optical elements that can use the above-described adhesive for optical elements are not limited to this embodiment. One embodiment of the optical element of this disclosure includes a first optical element, an adhesive layer, and a second optical element in this order, and the adhesive layer includes a cured product of the above-described adhesive for optical elements.

[0103] Since the adhesive layer is a cured product of an adhesive for optical components according to one embodiment of the present disclosure, changes in optical properties such as refractive index and yellowing before and after high temperature and high humidity testing are suppressed. Preferably, the absolute value of the difference in refractive index between the adhesive layer and at least one of the refractive indices of the first optical component and the second optical component is 0.005 or less, more preferably 0.002 or less, and even more preferably 0.001 or less. The first optical component and the second optical component are, for example, transparent optical resins for forming the geometric waveguide of AR glasses. The geometric waveguide is a laminated structure of transparent optical resin and adhesive, and the adhesive for optical components according to one embodiment of the present disclosure is useful as an adhesive in this laminated structure. Therefore, the optical element according to one embodiment of the present disclosure is preferably for AR glasses.

[0104] In this specification, "optical component" refers to materials used to utilize optical phenomena, such as lenses, mirrors, and prisms. Furthermore, "optical element" refers to a component of an optical device that performs an optical function by combining optical components, etc.

[0105] The following describes in more detail, with reference to examples, an adhesive for optical components, which is one embodiment of the present disclosure. The present disclosure is not limited to the following examples unless it exceeds the spirit of the disclosure.

[0106] <Preparation of materials> The following compounds were used in the following examples and comparative examples.

[0107] (Photocurable Compounds) =Epoxy Compounds= ・EP-4010S (Classification: Glycidyl ether type epoxy resin) (Polycondensate of bisphenol A, propylene oxide and epichlorohydrin, ADEKA Corporation) ・jER YL983U (Classification: Glycidyl ether type epoxy resin) (Bisphenol F type liquid epoxy resin, Mitsubishi Chemical Corporation) ・Celoxide 2021P (Classification: Alicyclic epoxy resin) (3,4-Epoxycyclohexylmethyl (3,4-Epoxy)cyclohexanecarboxylate, Daicel Corporation) ・jER YX8000D (Classification: Hydrogenated epoxy resin) (Hydrogenated bisphenol A type liquid epoxy resin, Mitsubishi Chemical Corporation) =Oxetanyl Group-Containing Compounds= ・Aronoxetane OXT-221 (Classification: Oxetanyl group-containing compound) (3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, Toagosei Co., Ltd.)

[0108] (Cationic polymerization initiators) ・CPI-310B (triarylsulfonium salt, Sunapro Co., Ltd., has maximum absorption at a wavelength of less than 400 nm) ・IK-1 (iodonium salt, Sunapro Co., Ltd., has maximum absorption at a wavelength of less than 300 nm) (Coupling agent) ・KBM-403 (3-glycidoxypropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd.)

[0109] (Antioxidants) ・ADEKA STAB AO-503 (Classification: Thioether-based antioxidant) (Ditridecyl thiodipropionate, ADEKA Corporation) ・ADEKA STAB AO-60 (Classification: Phenolic antioxidant) (Tetrakiss[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, ADEKA Corporation) ・Irganox 1010 (Classification: Phenolic antioxidant) (Pentaerythritol = Tetrakiss[3-(3',5'-ditert-butyl-4'-hydroxyphenyl)propionate], BASF Japan Ltd.) ・ADEKA STAB HP-10 (Classification: Phosphate antioxidant) (2,2'-Methylenebis(4,6-di-tert-butyl-1-phenyloxy)(2-ethylhexyloxy)phosphorus, ADEKA Corporation) ・ADEKA Stab PEP-36 (Classification: Phosphate antioxidant) (3,9-Bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, ADEKA Corporation)

[0110] (Hindered amine light stabilizers (HALS)) ・Tinuvin 123 (sterically hindered amine light stabilizer, reaction product mainly composed of bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) ester decanediate, BASF Japan Ltd.)

[0111] <Examples 1 to 5> Adhesives for optical components were prepared according to the compositions shown in Table 1 for each example. In Table 1, the "Epoxy Resin" column includes alicyclic epoxy compounds and other epoxy compounds. In Table 1, the unit of the numerical values ​​in the composition is parts by mass. In Table 1, a blank space means that the target compound is not included.

[0112] <Comparative Examples 1 to 7> In each case, an adhesive for optical components was prepared with the composition shown in Table 1. In Comparative Example 6, the curing of the adhesive for optical components was insufficient, so "Uncured" was written in the "Film Status" column in Table 1.

[0113] <Evaluation> The refractive index and yellow index of the cured products were measured using the optical component adhesives prepared in Example 1 and Example 2, and Comparative Examples 1 to 6, respectively, by the method described below. The measurement results are shown in Table 1.

[0114] (Refractive Index) A PET film (MelinexS) was placed on top of a glass plate (EAGLE-XG, manufactured by Corning), a 100 μm thick spacer was placed around the outer edge, and a resin composition was dripped into the center. The PET film and glass plate were then stacked in that order, sandwiching the spacer and resin composition, and secured with clips. After that, light with a wavelength of 365 nm was applied at 3000 mJ / cm². ２ A cured film was prepared by irradiation. The refractive index of the cured film was then measured using an Abbe refractometer (DR-M2, manufactured by Atago). RE-3520 (589 nm, D-line, manufactured by Atago) was used as the interference filter, and RE-1196 (monobromonaphthalene, manufactured by Atago) was used as the intermediate solution. The sample temperature was set to 25 degrees Celsius for the measurement. The evaluation criteria were as follows. The measurement results and evaluation results are shown in Table 1. In Table 1, the actual measured values ​​are also shown in parentheses. (Evaluation Criteria) A: Absolute value of the difference in refractive index is less than 0.002 B: Absolute value of the difference in refractive index is 0.002 or more

[0115] (Yellow Index (YI)) A 10 μm thick spacer was placed on the outer edge of a glass plate (EAGLE-XG, manufactured by Corning), and a resin composition was dripped into the center. The glass plate was then placed on top of the spacer and resin composition, sandwiched between them, and secured with a clip. After that, light with a wavelength of 365 nm was applied at 3000 mJ / cm². ２Test specimens were prepared by irradiation. The change in color intensity over approximately 24 hours in a high-temperature, high-humidity test chamber at 65°C and 90% Rh was measured using a spectrochromic haze meter (COH 7700, manufactured by Nippon Denshoku Industries Co., Ltd.). The ratio of the change was calculated and evaluated using the formula: "Change in color intensity = (YI value after heating at 65°C, 90% Rh, 24 hours) / (YI value before heating at 65°C, 90% Rh, 24 hours)". The evaluation criteria were as follows. The measurement results and evaluation results are shown in Table 1. Actual measured values ​​are also shown in parentheses in Table 1. (Evaluation Criteria) A: Change in color intensity is less than 2 times B: Change in color intensity is 2 times or more

[0116]

[0117] As shown in Table 1, the adhesives of Examples 1 and 2 contained an alicyclic epoxy compound, an oxetanyl group-containing compound, HALS, and an antioxidant. In the cured product, the absolute value of the difference in refractive index before and after the high-temperature and high-humidity test was less than 0.002, indicating that changes in optical properties were suppressed. For each of Examples 1 to 5, the adhesives of Comparative Examples 1 to 5 and Comparative Example 7 showed a change in optical properties, with the absolute value of the difference in refractive index before and after the high-temperature and high-humidity test being 0.002 in the cured product. The adhesive of Comparative Example 6 did not cure and its function as an adhesive was insufficient.

[0118] The disclosure of Japanese Patent Application No. 2024-231087, filed on 26 December 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. An adhesive for optical components comprising an alicyclic epoxy compound, an oxetanyl group-containing compound, a hindered amine-based light stabilizer, and an antioxidant, wherein the adhesive for optical components is exposed to light with a wavelength of 365 nm at an energy density of 3000 mJ / cm². ２ An adhesive for optical components, prepared by irradiation with a thickness of 100 μm, wherein the cured product of the adhesive for optical components exhibits an absolute value of the difference in refractive index less than 0.002 before and after a high-temperature and high-humidity test in which the cured product is exposed to an environment of 65°C and 90% RH for 24 hours.

2. The adhesive for optical components according to claim 1, wherein the cured product has a refractive index of 1.520 to 1.575 when the high temperature and high humidity test has not been performed.

3. The adhesive for optical components according to claim 1, wherein the cured product has a refractive index of 1.540 to 1.555 when the high temperature and high humidity test has not been performed.

4. The adhesive for optical components according to claim 1, wherein the yellow index of the cured product after the high temperature and high humidity test is less than twice that of the product before the high temperature and high humidity test.

5. The adhesive for optical components according to claim 1, comprising multiple types of antioxidants.

6. The adhesive for optical components according to claim 5, wherein when the total amount of the alicyclic epoxy compound and the oxetanyl group-containing compound is 100 parts by mass, each of the multiple types of antioxidants is contained in an amount of less than 5.00 parts by mass.

7. The adhesive for optical components according to claim 5, wherein when the total amount of the alicyclic epoxy compound and the oxetanyl group-containing compound is 100 parts by mass, each of the multiple types of antioxidants is contained in an amount of less than 1.00 part by mass.

8. The adhesive for optical components according to claim 1, wherein the content of the hindered amine-based light stabilizer is 1 part by mass or less.

9. The adhesive for optical components according to claim 1, wherein the antioxidant comprises a phenolic antioxidant and a thioether-based antioxidant.

10. An optical element comprising a first optical element, an adhesive layer, and a second optical element in this order, wherein the adhesive layer includes a cured product of an adhesive for optical elements according to any one of claims 1 to 9.

11. The optical element according to claim 10, wherein the adhesive layer has an absolute difference in refractive index of 0.005 or less with respect to at least one of the refractive indices of the first optical member and the second optical member.

12. The optical element according to claim 10, which is a lens.

13. The optical element according to claim 12, wherein the lens is for a virtual reality device, a mixed reality device, an augmented reality device, a cross-reality device, or a head-mounted display.

14. The optical element according to claim 10, which is for use with AR glasses.

15. An optical device including an optical element, wherein the optical element comprises a first optical member, an adhesive layer, and a second optical member in that order, the adhesive layer comprises a cured product of an adhesive for optical members containing an alicyclic epoxy compound, an oxetanyl group-containing compound, a hindered amine-based light stabilizer, and an antioxidant, and the adhesive for optical members is exposed to light with a wavelength of 365 nm at an energy density of 3000 mJ / cm². ２ An optical instrument in which a cured product of the adhesive for optical components, with a thickness of 100 μm, produced by irradiation, has an absolute value of the difference in refractive index less than 0.002 before and after a high-temperature and high-humidity test in which the cured product is exposed to an environment of 65°C and 90% RH for 24 hours.

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