Curing method for cationic polymerizable epoxy resin composition

Abstract

The present invention relates to a method for curing a cationic polymerizable epoxy resin composition, the method comprising: irradiating the cationic polymerizable epoxy resin composition with a UV, visible, or infrared laser; and maintaining the temperature of the cationic polymerizable epoxy resin composition between 25°C higher than the curing reaction peak temperature of the cationic polymerizable epoxy resin composition measured by differential scanning calorimetry and 275°C, wherein the cationic polymerizable epoxy resin composition comprises (A) epoxy resin and (B) an acid generator.

Description

Technical Field

[0001] The present invention relates to a method for curing a cationic polymerizable epoxy resin composition.

Background Art

[0002] Adhesive technology is increasingly being used for bonding optical device components such as camera modules and LiDAR (light detection and ranging) modules. For example, US2015 / 0124098A discloses a dual-cure type epoxy adhesive that can be cured by both light and heat for bonding lens components of an in-vehicle camera module. The adhesive is temporarily cured by UV irradiation so that the optical axis of the lens does not shift immediately after adjustment, and then is firmly cured by heat. However, this technology requires a long curing process using heat, which poses a problem from the perspective of production efficiency. In addition, JP2022-136720A discloses the use of a laser beam for curing a cationic polymerizable epoxy adhesive composition, and the process can be completed in a short time. However, when the adhesive is irradiated with a laser beam, the temperature of the adhesive continues to rise rapidly, and there is a possibility that the adhesive will decompose before sufficient curing strength is obtained.

Prior Art Documents

[0005] The object of the present invention is to provide a method for curing a cationic polymerizable epoxy resin composition that hardens the adhesive composition in a short time without decomposing the adhesive. [Means for solving the problem]

[0006] The inventors have conducted extensive research to achieve the above objective and have found that this objective can be achieved by a method comprising irradiating a cationic polymerizable epoxy resin composition with a UV, visible, or infrared laser, and maintaining the surface temperature of the cationic polymerizable epoxy resin composition between 25°C higher and 275°C than the curing reaction peak temperature of the cationic polymerizable epoxy resin composition as measured by differential scanning calorimetry, wherein the cationic polymerizable epoxy resin composition comprises (A) epoxy resin and (B) an acid generator. The present invention was achieved by further research based on this discovery. The present invention includes the following embodiments.

[0007] [Section 1] 1) Irradiating a cationic polymerizable epoxy resin composition with a UV, visible, or infrared laser, and 2) Maintain the surface temperature of the cationic polymerizable epoxy resin composition between 25°C higher than the curing reaction peak temperature of the cationic polymerizable epoxy resin composition, as measured by differential scanning calorimetry, and 275°C. A method for curing a cationic polymerizable epoxy resin composition, comprising: Cationic polymerizable epoxy resin composition: (A) epoxy resin; and (B) Acid generator A curing method that includes [this].

[0008] [Section 2] A method for curing a cationic polymerizable epoxy resin composition according to item 1, wherein the epoxy resin (A) includes an alicyclic epoxy resin.

[0009] [Section 3] A method for curing a cationic polymerizable epoxy resin composition according to item 2, wherein the epoxy resin (A) further comprises a glycidyl ether epoxy resin.

[0010] [Section 4] A method for curing a cationic polymerizable epoxy resin composition according to any one of items [1] to [3], wherein the surface temperature of the cationic polymerizable epoxy resin composition is maintained between a temperature 30°C higher than the curing reaction peak temperature of the cationic polymerizable epoxy resin composition measured by differential scanning calorimetry and 250°C.

[0011] [Section 5] A method for curing a cationic polymerizable epoxy resin composition according to any one of items [1] to [4], wherein the cationic polymerizable epoxy resin composition further comprises (C) an oxetane resin.

[0012] [Section 6] A method for curing a cationic polymerizable epoxy resin composition according to any one of items [1] to [5], further comprising (D) an inorganic filler.

[0013] [Section 7] A method for curing a cationic polymerizable epoxy resin composition according to any one of items [1] to [6], wherein the acid generator (B) is a photoacid generator or a thermal acid generator.

[0014] [Section 8] A method for curing a cationic polymerizable epoxy resin composition according to any one of items [1] to [7], wherein the cationic polymerizable epoxy resin composition is curable by a visible or infrared laser having a wavelength of 300 to 1200 nm.

[0015] [Section 9] Controlling the laser irradiation so that the time from the start of laser irradiation to reaching the surface temperature of the cationic curable epoxy resin composition is 0.1 to 30 seconds, the method for curing a cationic curable epoxy resin composition according to any one of [Item 1] to [Item 8].

[0016] [Item 10] Controlling the laser irradiation so that the time from the start of laser irradiation to reaching the surface temperature of the cationic curable epoxy resin composition is 1 to 25 seconds, the method for curing a cationic curable epoxy resin composition according to any one of [Item 1] to [Item 9].

[0017] [Item 11] The method for curing a cationic curable epoxy resin composition according to any one of [Item 1] to [Item 10], for use in at least one application selected from the group consisting of metal bonding, assembly of a camera module, and assembly of an electronic sensor. [Advantages of the Invention]

[0018] The method for curing a cationic curable epoxy resin composition of the present invention enables the epoxy adhesive composition to be cured in a shorter time without decomposition of the cured epoxy adhesive. [Modes for Carrying Out the Invention]

[0019] The method for curing a cationic curable epoxy resin composition of the present invention includes at least the following two steps: 1) a step of irradiating a cationic curable epoxy resin composition containing (A) an epoxy resin and (B) an acid generator with UV, visible, or infrared laser, and 2) a step of maintaining the surface temperature of the cationic curable epoxy resin composition between a temperature 25°C higher than the curing reaction peak temperature of the cationic curable epoxy resin composition measured by differential scanning calorimetry and 275°C.

[0020] In one embodiment, the curing method further includes a step of applying the cationic curable epoxy resin composition onto a first substrate and / or a second substrate.

[0021] The first and / or second substrates may be a single material and a single layer, or may consist of multiple layers of the same or different materials. The layers may be continuous or discontinuous.

[0022] The substrates described herein may have a variety of properties, including rigidity (e.g., rigid substrates, i.e., substrates that cannot be bent even with both hands, or that break when bent with both hands), flexibility (e.g., flexible substrates, i.e., substrates that can be bent with less force than that of both hands), porosity, conductivity, lack of conductivity, and combinations thereof.

[0023] The substrates used herein may take various forms, including, for example, fibers, yarns, threads, fabrics, nonwovens, films (e.g., polymer films, metallized polymer films, continuous films, discontinuous films, and combinations thereof), foils (e.g., metallic foils), sheets (e.g., metallic sheets, polymer sheets, continuous sheets, discontinuous sheets, and combinations thereof), and combinations thereof.

[0024] In a preferred embodiment, at least one substrate may be selected from metal-fired paste, metals such as aluminum, tin, molybdenum, and silver, conductive metal oxides such as indium tin oxide (ITO), fluorine-doped tin oxide, and aluminum-doped zinc oxide, glass such as ink-coated glass and bare glass, and resins such as polycarbonate, polybutylene terephthalate, polyethylene terephthalate, and polyamide. More suitable metals include copper, gold, palladium, platinum, aluminum, indium, silver-coated copper, silver-coated aluminum, tin, and tin-coated copper. Preferably, both substrates are selected from one of the above materials. More preferably, both substrates are glass.

[0025] Cationic polymerizable epoxy resin compositions can be applied to first and / or second substrates using any suitable application method, such as automatic fine wire dispensing, jet dispensing, slot die coating, roll coating, gravure coating, transfer coating, pattern coating, screen printing, spray coating, filament coating, extrusion, air knife, trailing blade, brush coating, dip coating, doctor blade, offset gravure coating, rotogravure coating, and combinations thereof. Cationic polymerizable epoxy resin compositions can be applied as continuous or discontinuous coatings, single or multilayer coatings, and combinations thereof.

[0026] In the present invention, the UV, visible, or infrared laser irradiated onto the cationic polymerizable epoxy resin composition refers particularly to a laser having a wavelength of 300 to 1200 nm. The cationic polymerizable epoxy resin composition of the present invention can be cured using a laser having a wavelength of preferably 350 to 1100 nm, more preferably 400 to 1100 nm.

[0027] The generation of lasers in such wavelength ranges is known in the art. Preferably, the laser is provided by a laser diode device. Examples of commercially available such devices include Panasonic Corporation's CB series products such as CB1F, CB3, CB5, and CB20.

[0028] In the second step, the surface temperature of the cationic polymerizable epoxy resin composition is maintained between 25°C higher and 275°C than the curing reaction peak temperature of the cationic polymerizable epoxy resin composition measured by differential scanning calorimetry.

[0029] Preferably, the surface temperature of the cationic polymerizable epoxy resin composition is maintained between 30°C higher than the curing reaction peak temperature of the cationic polymerizable epoxy resin composition measured by differential scanning calorimetry and 250°C. If the temperature is too high, the cured adhesive may have a worse appearance due to combustion, as the decomposition temperature of the cured product of such a cationic polymerizable epoxy resin composition is approximately 275°C. If the temperature is too low, the adhesive composition may not cure completely, and sufficient adhesive performance may not be achieved. By stabilizing the surface temperature to the set temperature within a short time using laser output control, a good appearance and sufficient adhesive performance of the cured adhesive can be obtained.

[0030] The curing reaction peak temperature of a cationic polymerizable epoxy resin composition can be measured using a differential scanning calorimeter, such as the DSC6000 from Seiko Instruments Inc., under a nitrogen atmosphere, in a temperature range of 25°C to 200°C, at a heating rate of 10°C / min.

[0031] The laser irradiation is controlled so that the time from the start of laser irradiation to the reaching of the surface temperature of the cationic polymerizable epoxy resin composition is 0.5 to 30 seconds, preferably 1 to 25 seconds, more preferably 1 to 20 seconds. Preferably, the total irradiation time is 1 to 60 seconds, preferably 2 to 30 seconds, and the holding time refers to the difference between the total irradiation time and the time to reach the surface temperature, which is 0.5 to 30 seconds, preferably 1 to 20 seconds. Controlling the irradiation and holding time within such ranges can improve the appearance and / or curability of the cured adhesive.

[0032] The surface temperature of a cationic epoxy resin composition can be measured by methods known in the art. Preferably, the measurement is performed without touching the surface of the cationic epoxy resin composition. The method for non-contact measurement of the adhesive surface temperature is not particularly limited, but examples include a structure combining a temperature sensor that detects infrared radiation emitted from the adhesive composition and a computing device that calculates the temperature of the adhesive composition. The method for controlling the output is not particularly limited, but for example, by connecting the computing device and the laser in a controllable manner, the output of the laser can be adjusted according to the calculation result of the computing device. In this configuration, when the surface temperature of the adhesive composition is detected and the temperature exceeds a set temperature, a command signal can be sent to the laser to control the output, thereby adjusting the output appropriately. Preferably, a laser diode device that generates UV, visible, and infrared lasers has a radiation thermometer with a configuration for controlling such working temperatures.

[0033] The epoxy resin composition in the curing method is cationic polymerizable and comprises (A) epoxy resin and (B) an acid generator.

[0034] The epoxy resin used in this invention is not particularly limited as long as the epoxy resin undergoes cationic polymerization. The reaction mechanism of cationic polymerization of epoxy resins is well known. In particular, the epoxy resin used in this invention may be any polymerization system in which the growth chain is a carbon cation (carbocation). The epoxy resin used in this invention forms a carbocation by reacting with an acid generated by an acid generator. A growth reaction occurs between this carbocation and the epoxy resin used in this invention, thereby ultimately providing a cured product.

[0035] The epoxy resin used in this invention may be a single epoxy resin, or a combination of two or more epoxy resins as needed.

[0036] From the viewpoint of excellent curability, the epoxy resin used in the present invention preferably includes an alicyclic epoxy resin. An alicyclic epoxy resin refers to an epoxy resin having an alicyclic ring in its molecule, sharing a portion of the carbon-carbon bonds that form the alicyclic ring with the epoxy ring. The alicyclic epoxy resin used may be any known alicyclic epoxy resin.

[0037] When the epoxy resin used in the present invention includes an alicyclic epoxy resin, from the viewpoint of curability, the epoxy resin contains the alicyclic epoxy resin in an amount of preferably 3% by weight or more, more preferably 5% by weight or more, and even more preferably 10% by weight or more, based on the total amount of epoxy resin.

[0038] The alicyclic epoxy resin used in the present invention has, for example, an epoxy equivalent of 100 to 500, preferably 100 to 400, and more preferably 100 to 300.

[0039] Examples of alicyclic epoxy resins used in the present invention are not particularly limited, but include the following: (3',4'-epoxycyclohexane)methyl 3,4-epoxycyclohexyl carboxylate (Celloxide 2021P (CEL2021P) manufactured by Daicel Corporation), ε-caprolactone-modified 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexane carboxylate (Celloxide 2081 (CEL2081) manufactured by Daicel Corporation), 1,2-epoxy-4-vinylcyclohexane (Celloxide 2000 (CEL2000) manufactured by Daicel Corporation), (Celloxide 8010 (CEL8010) manufactured by Daicel Corporation), (KR-470 manufactured by Shin-Etsu Chemical Co., Ltd.), and similar products.

[0040] From the viewpoint of imparting flexibility to the cured product, the epoxy resin used in the present invention preferably comprises at least one epoxy resin selected from the group consisting of glycidyl ether epoxy resins and glycidyl ester epoxy resins. Compared to alicyclic epoxy resins, these epoxy resins have a slower growth reaction, so the curing reaction persists even after laser irradiation, and the molecular weight only grows to about a few thousand. Therefore, these epoxy resins can impart desirable flexibility to the final cured product.

[0041] The glycidyl ether epoxy resin and glycidyl ester epoxy resin used in the present invention have epoxy equivalents of, for example, 100 to 1000, preferably 100 to 800, and more preferably 100 to 600, respectively.

[0042] The glycidyl ether epoxy resin and glycidyl ester epoxy resin used in the present invention are preferably liquid or semi-solid at room temperature (approximately 23°C), but if they are solid, they can be dissolved before use.

[0043] Glycidyl ether epoxy resins and glycidyl ester epoxy resins preferably have an aromatic structure in their main chain. Glycidyl ether epoxy resins and glycidyl ester epoxy resins may have a polycyclic aromatic structure (such as naphthalene or anthracene) in their main chain.

[0044] The epoxy resin added to impart flexibility to the cured product is preferably a glycidyl ether epoxy resin. Examples of glycidyl ether epoxy resins include bisphenol-type glycidyl ethers.

[0045] Examples of bisphenol-type glycidyl ethers include bisphenol A glycidyl ether, bisphenol F glycidyl ether, bisphenol AP glycidyl ether, bisphenol B glycidyl ether, bisphenol C glycidyl ether, bisphenol E glycidyl ether, bisphenol G glycidyl ether, and similar substances.

[0046] Preferred bisphenol A glycidyl ethers include EPICLON 840 (manufactured by DIC Corporation), EPICLON 840S (manufactured by DIC Corporation), EPICLON 850 (manufactured by DIC Corporation), EPICLON 850S (manufactured by DIC Corporation), EXA-850CRP (manufactured by DIC Corporation), EXA-850LC (manufactured by DIC Corporation), EXA-860 (manufactured by DIC Corporation), EXA-1050 (manufactured by DIC Corporation), EXA-1055 (manufactured by DIC Corporation), 825 (manufactured by Mitsubishi Chemical Corporation), 827 (manufactured by Mitsubishi Chemical Corporation), 828 (manufactured by Mitsubishi Chemical Corporation), 1001 (manufactured by Mitsubishi Chemical Corporation), 1002 (manufactured by Mitsubishi Chemical Corporation), RE-310S (manufactured by Nippon Kayaku Co., Ltd.), and similar products.

[0047] Preferred bisphenol F glycidyl ethers include EXA-830 (manufactured by DIC Corporation), EXA-830S (manufactured by DIC Corporation), EXA-835 (manufactured by DIC Corporation), EXA-830CRP (manufactured by DIC Corporation), EXA830LVP (manufactured by DIC Corporation), EXA835LV (manufactured by DIC Corporation), 806 (manufactured by Mitsubishi Chemical Corporation), 806H (manufactured by Mitsubishi Chemical Corporation), 807 (manufactured by Mitsubishi Chemical Corporation), and RE-303SL (manufactured by Nippon Kayaku Co., Ltd.); phenol aralkyl epoxys include NC3000L (manufactured by Nippon Kayaku Co., Ltd.), NC2000L (manufactured by Nippon Kayaku Co., Ltd.), and similar products.

[0048] In the present invention, if the epoxy resin used includes a glycidyl ether epoxy resin and / or a glycidyl ester epoxy resin, the epoxy resin contains the glycidyl ether epoxy resin and the glycidyl ester epoxy resin in a total amount of preferably 3% by weight or more, more preferably 5% by weight or more, and even more preferably 10% by weight or more, based on the total amount of the epoxy resin, in order to impart flexibility to the cured product.

[0049] The acid generator used in the present invention is not particularly limited, as long as it generates acid directly or indirectly by the use of a visible or infrared laser, and as long as the acid reacts with epoxy resin (A) to produce a carbocation.

[0050] Examples of acid generators that directly or indirectly produce acid using visible or infrared lasers include photoacid generators and similar compounds. A photoacid generator is a compound that produces acid upon irradiation with light. A photoacid generator has a light-absorbing portion and a portion that functions as an acid source within its molecule. Examples, though not limited to them, include onium salts and similar compounds having a cationic portion and an anionic portion. In these onium salts, the cationic portion corresponds to the light-absorbing portion, while the anionic portion functions as an acid source.

[0051] As the cationic portion, the onium salt may include sulfonium ions, iodonium ions, phosphonium ions, quaternary ammonium ions, diazonium ions, or similar. The sulfonium ion used may be, for example, a triarylsulfonium ion.

[0052] As the anionic part, the onium salt is PF6 - SbF6 - BF4 - , or similar things.

[0053] Examples of photoacid generators include CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-310B, CPI-310FG, CPI-410S, and IK-1, all manufactured by Sunapro Co., Ltd.; IRGACURE 250 and IRGACURE 270, both manufactured by Ciba Specialty Chemicals Inc.; BLUESIL PI 2074, manufactured by Elkem; and similar products.

[0054] Examples of acid generators that directly or indirectly produce acid using visible or infrared lasers include thermal acid generators and similar agents. Thermal acid generators are compounds that produce acid by absorbing heat. The heat generated by a visible or infrared laser allows the thermal acid generator to produce acid. If necessary, for example, inorganic fillers or similar substances may be appropriately incorporated into the cationic polymerizable epoxy resin composition of the present invention, thereby making it easier to generate heat by irradiation with a visible or infrared laser, and thus making it easier to generate acid from the thermal acid generator.

[0055] Examples of thermal acid generators include (TGA CXC1612 and TGA CXC1821, both manufactured by King Industries, Inc.), (San-aid SI-B2A, manufactured by Sanshin Chemical Industry Co., Ltd.), (San-aid SI-B7, manufactured by Sanshin Chemical Industry Co., Ltd.), (San-aid SI-B3A, manufactured by Sanshin Chemical Industry Co., Ltd.), (San-aid SI-B3, manufactured by Sanshin Chemical Industry Co., Ltd.), (San-aid SI-B5, manufactured by Sanshin Chemical Industry Co., Ltd.), and similar products.

[0056] The acid generator used in the present invention may be a single acid generator, or a combination of two or more acid generators as needed.

[0057] The cationic polymerizable epoxy resin composition of the present invention contains an acid generator in an amount based on the total amount of the cationic polymerizable epoxy resin composition, for example, 0.01 to 10% by weight, preferably 0.1 to 8% by weight, more preferably 0.1 to 5% by weight, and even more preferably 0.1 to 3% by weight.

[0058] The cationic polymerizable epoxy resin composition of the present invention preferably contains an oxetane resin.

[0059] The oxetane resin is not particularly limited as long as the resin has an oxetane ring in its molecule. Preferably, the oxetane compound has a 3-oxetanyl group and may have other functional groups as needed. The oxetane compound has at least one oxetane ring in its molecule, but preferably two or more oxetane rings. The oxetane equivalent of the polyfunctional monomer having two or more oxetane groups is not particularly limited, but is preferably 400 or less, more preferably 300 or less, and preferably 100 or more.

[0060] Oxetane compounds are not particularly limited, and examples include bis[1-ethyl(3-oxetanyl)]methyl ether[(3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane)] represented by the following formula (a1-1), xylenebisoxetane represented by the following formula (a1-2), 4,4'-bis[3-ethyl-(3-oxetanyl)methoxymethyl]biphenyl, 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-(4-hydroxybutyl)oxymethyloxetane, 1,4-bis(3-ethyl-3-oxetanylmethoxy)methylbenzene, (3-ethyloxetan-3-yl)methyl methacrylate, (bis[(3-ethyl-3-oxetanyl)methyl]isophthalate), and similar compounds.

[0061] Oxetane compounds may be used individually or in combination of two or more.

[0062] In one embodiment of this model, it is preferable to include 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, represented by the following formula (a1-1), as component (a1). The amount of the compound represented by formula (a1-1) is preferably 80% by mass or more, and may be 100% by mass, based on the total amount of component (a1).

[0063] [ka] TIFF2026524135000002.tif38132

[0064] An example of a commercially available compound represented by formula (a1-1) is OXT-221 (trademark, manufactured by Toagosei Co., Ltd.). In addition, examples of commercially available oxetane compounds include OXT-212, OXT-101, and OXT-121 manufactured by Toagosei Co., Ltd., as well as EHO, OXMA, OXBP, HBOX, and OXIPA manufactured by UBE Corporation.

[0065] The cationic polymerizable epoxy resin composition of the present invention may further contain an inorganic filler.

[0066] The inorganic filler used in this invention may be a single inorganic filler or, if necessary, a combination of two or more inorganic fillers.

[0067] Examples of inorganic fillers used in the present invention include silica fillers such as colloidal silica, hydrophobic silica, fine silica, and nanosilica, as well as acrylic beads, glass beads, urethane beads, bentonite, acetylene black, Ketjenblack, and similar materials.

[0068] The inorganic filler used in the present invention may have, for example, a volume-average particle diameter (or, if the filler is not particulate, its maximum weight-average diameter) of 0.01 to 50 μm, preferably 0.1 to 40 μm, and more preferably 1 to 30 μm. In this specification, the volume-average particle diameter of the inorganic filler is measured in particular by a dynamic light scattering nanotrac particle size analyzer.

[0069] Examples of commercially available inorganic fillers include high-purity synthetic spherical silica (SO-E5, average particle size: 2 μm; SO-E2, average particle size: 0.6 μm, both manufactured by Admatechs), silica (FB7SDX, manufactured by Ryumori Co., Ltd., average particle size: 10 μm), silica (TS-10-034P, manufactured by Micron, average particle size: 20 μm), and similar products.

[0070] The cationic polymerizable epoxy resin composition of the present invention contains an inorganic filler in an amount of, for example, 40 to 80% by weight, preferably 50 to 70% by weight, based on the total amount of the cationic polymerizable epoxy resin composition.

[0071] The cationic polymerizable epoxy resin composition of the present invention may further contain one or more other components as needed.

[0072] Specific examples of other components include oxetane resins. Particularly from the viewpoint of imparting flexibility to the cured product, when a glycidyl ether epoxy resin or a glycidyl ester epoxy resin is included, the cationic polymerizable epoxy resin composition of the present invention preferably further contains an oxetane resin, thereby promoting the curing of those epoxy resins by an acid generator.

[0073] The cationic polymerizable epoxy resin composition of the present invention contains oxetane resin in an amount of, for example, 3 to 60% by weight, preferably 5 to 50% by weight, based on the total amount of the cationic polymerizable epoxy resin composition.

[0074] Other examples of components include adhesion aids (e.g., silanes), coupling agents (e.g., titanates), rheology modifiers (e.g., fumed silica), and similar substances.

[0075] Even without containing pigments, the cationic polymerizable epoxy resin composition of the present invention can be efficiently cured with visible or infrared lasers. The cationic polymerizable epoxy resin composition of the present invention may optionally contain pigments.

[0076] The curing method for the cationic polymerizable epoxy resin composition of the present invention is preferably used for assembling camera modules. More specifically, in the assembly of a camera module, the curing of the cationic polymerizable epoxy resin composition of the present invention is preferably used for bonding the lens holder to the substrate on which the image sensor is fixed. In the above, the camera module is not particularly limited and is, for example, a small camera module used in smartphones and the like.

[0077] Furthermore, the curing method for the cationic polymerizable epoxy resin composition of the present invention can also be used for assembling electronic sensors. [Examples]

[0078] The resin compositions for all examples were prepared by mixing the following components: 100 mg of 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate (Daicel Corporation, "Celoxide 2021P"), 100 mg of bisphenol A type epoxy resin (DIC Corporation, "EPICLON 840"), 100 mg of 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (Toagosei Co., Ltd., "OXT 221"), 3 mg of a thermoacid generator (King Industries, "TGA CXC1821"), and 500 mg of high-purity synthetic spherical silica (SO-E5, Admatechs, average particle size: 2 μm). Specifically, the above components were mixed, kneaded and dispersed using a three-roll mill, and then vacuum degassed to obtain the resin composition.

[0079] The curing test was conducted using the following method. The evaluation results are shown in Table 1.

[0080] [Curing Test Method] The curing reaction peak of the epoxy resin composition was measured using a Seiko Instruments Inc. DSC6000 differential scanning calorimeter under a nitrogen atmosphere at a temperature range of 25°C to 200°C at a heating rate of 10°C / min. The curing peak temperature was observed at 80°C.

[0081] An epoxy resin composition was applied to a glass slide in an amount of 0.01 cc. The resulting glass slide was then irradiated with a 980 nm laser at a 90-degree angle using a Panasonic Corporation CB1F laser diode device equipped with a radiation thermometer. The control temperature of the resin composition surface, the time to reach the control temperature, and the total irradiation time are shown in Table 1. The curing method was evaluated in terms of the appearance and curability of the cured product by touching it with a bamboo stick.

[0082] [Table 1]

[0083] In Examples 1, 2, and 3, when the cationic polymerizable epoxy resin composition was irradiated with a laser and the surface temperature was maintained within an appropriate temperature range, it cured completely with a good appearance. On the other hand, in Comparative Example 1, when a lower temperature was applied, the cationic polymerizable epoxy resin composition cured only partially. Furthermore, in Comparative Example 2, when a higher temperature was applied, the composition cured completely, but decomposition of the adhesive occurred after curing.

Claims

1. 1) Irradiating a cationic polymerizable epoxy resin composition with a UV, visible, or infrared laser, and 2) Maintain the surface temperature of the cationic polymerizable epoxy resin composition between 25°C higher than the curing reaction peak temperature of the cationic polymerizable epoxy resin composition, as measured by differential scanning calorimetry, and 275°C. A method for curing a cationic polymerizable epoxy resin composition, comprising: Cationic polymerizable epoxy resin composition: (A) epoxy resin; and (B) Acid Generator A curing method that includes [this].

2. A method for curing a cationic polymerizable epoxy resin composition according to claim 1, wherein the epoxy resin (A) includes an alicyclic epoxy resin.

3. A method for curing a cationic polymerizable epoxy resin composition according to claim 2, wherein the epoxy resin (A) further comprises a glycidyl ether epoxy resin.

4. A method for curing a cationic polymerizable epoxy resin composition according to any one of claims 1 to 3, wherein the surface temperature of the cationic polymerizable epoxy resin composition is maintained between a temperature 30°C higher than the curing reaction peak temperature of the cationic polymerizable epoxy resin composition measured by differential scanning calorimetry and 250°C.

5. A method for curing a cationic polymerizable epoxy resin composition according to any one of claims 1 to 4, wherein the cationic polymerizable epoxy resin composition further comprises (C) an oxetane resin.

6. A method for curing a cationic polymerizable epoxy resin composition according to any one of claims 1 to 5, wherein the cationic polymerizable epoxy resin composition further comprises (D) an inorganic filler.

7. A method for curing a cationic polymerizable epoxy resin composition according to any one of claims 1 to 6, wherein the acid generator (B) is a photoacid generator or a thermoacid generator.

8. A method for curing a cationic polymerizable epoxy resin composition according to any one of claims 1 to 7, wherein the cationic polymerizable epoxy resin composition can be cured by a UV, visible, or infrared laser having a wavelength of 300 to 1200 nm.

9. A method for curing a cationic polymerizable epoxy resin composition according to any one of claims 1 to 8, wherein the laser irradiation is controlled so that the time from the start of laser irradiation to reaching the surface temperature of the cationic polymerizable epoxy resin composition is 0.1 to 30 seconds, preferably 1 to 25 seconds.

10. A method for curing a cationic polymerizable epoxy resin composition according to any one of claims 1 to 9, for use in at least one application selected from the group consisting of metal bonding, camera module assembly, and electronic sensor assembly.

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