Energy ray-curable film-shaped transparent adhesive, device obtained by bonding constituent members using same, and method for producing said device

Abstract

Provided are: an energy ray-curable film-shaped transparent adhesive, wherein the cured product after a curing reaction is such that the light transmittance T1 (%) of the cured product at a wavelength of 400 nm is 80.0% or greater, and the light transmittance T1 and the light transmittance T2 (%) of a heat-treated cured product at a wavelength of 400 nm satisfy T1 − T2 ≤ 5%, the heat-treated cured product being obtained by subjecting the cured product to a heat treatment at 150°C for 100 hours; a device using said adhesive; and a method for producing said device.

Description

Energy ray curing film-type transparent adhesive, a device formed by bonding components using the same, and a method for manufacturing the device.

[0001] The present invention relates to an energy-ray curable film-type transparent adhesive, a device formed by bonding components using the same, and a method for manufacturing the device.

[0002] Digital still cameras and digital video cameras incorporate image sensors (image sensors) such as CMOS image sensors and CCD image sensors. The image sensor converts incident light into an electrical signal using a photodiode, and then processes this signal to form a digital image. Depending on the requirements, color filters and microlenses are placed on the surface of the photodiode, and a transparent protective film, usually made of glass, is typically placed on the surface of the laminate. Such transparent protective films are generally fixed in place via a curable film-like adhesive. The curable film-like adhesive used to bond or fix the transparent protective film to the image sensor must have sufficient transparency to transmit light after the curing reaction.

[0003] Curable film adhesives used in image display devices also require sufficient transparency after curing so as not to affect the color of the displayed image. Image display devices consist of functional elements (such as organic electroluminescent (OLED) elements, liquid crystal panels, micro-light-emitting diodes (micro-LEDs), and semiconductor elements such as transistors) arranged on a support substrate, and functional layers (such as protective layers, gas barrier layers (encapsulation layers), and hardcoded layers) may be arranged on the surface of the functional elements. Curable film adhesives are used to bond or fix these functional elements and functional layers.

[0004] The image sensors and functional elements mentioned above are precision electronic components (precision building blocks), and in the manufacture of devices equipped with them, it is desirable to avoid (or minimize) heat treatment as much as possible to avoid damaging the precision electronic components. Therefore, it is desirable that the curable film-like adhesive used in the above manufacture does not require heating for its curing reaction and that sufficient curing reaction occurs with the least possible amount of energy applied. Patent Document 1 describes an energy-ray curable film-like transparent adhesive containing an epoxy resin, a phenoxy resin, and a photocationic polymerization initiator containing antimony in the anionic part, as a technology that addresses this requirement. According to Patent Document 1, by using the above component composition for the film-like transparent adhesive, it is possible to obtain a film-like transparent adhesive that can be cured with a small amount of energy irradiation, exhibits sufficient adhesive strength, has excellent transparency after curing, and whose adhesive strength does not decrease even at high temperatures.

[0005] International Publication No. 2024 / 005071

[0006] With the proliferation of devices containing precision electronic components, the operating environments for these devices are also diversifying. For example, when devices are installed outdoors, used outdoors, or installed inside vehicles, they are exposed to considerably high temperatures, such as during the summer. Therefore, it is necessary to maintain the quality of the devices over the long term even under such harsh conditions. From this perspective, for example, in the manufacture of devices equipped with precision electronic components for image formation (e.g., image sensors and image display devices), the curable film adhesive used is required not only to have high transparency in its cured product, but also to be able to sustainably maintain that transparency even at high temperatures. And it is expected that this requirement will become even more sophisticated in the future.

[0007] The present invention aims to provide an energy-ray curable film-type transparent adhesive in which the cured product exhibits excellent transparency after the curing reaction and can sustainably maintain this transparency even at high temperatures. Furthermore, the present invention aims to provide a device using the above-mentioned energy-ray curable film-type transparent adhesive for bonding constituent members, and a method for manufacturing the device.

[0008] The above problems of the present invention are solved by the following means: [1] An energy-ray curable film-type transparent adhesive, wherein, for the cured product after the curing reaction, the light transmittance T1 (%) of the cured product at a wavelength of 400 nm is 80.0% or more, and the light transmittance T1 and the light transmittance T2 (%) of a heat-treated cured product obtained by heat-treating the cured product at 150°C for 100 hours satisfy T1 - T2 ≤ 5%. [2] The energy-ray curable film-type transparent adhesive according to [1], wherein the glass transition temperature of the cured product is 100°C or more. [3] The energy-ray curable film-type transparent adhesive according to [1] or [2], wherein the energy-ray curable film-type transparent adhesive contains an epoxy resin, a phenoxy resin, and a photocationic polymerization initiator. [4] The energy-ray curable film-type transparent adhesive according to [3], wherein the epoxy resin contains an epoxy compound having an epoxycycloalkane structure. [5] The energy ray curable film-type transparent adhesive according to [4], wherein the number of ring constituent carbon atoms in the epoxycycloalkane structure is 5 to 8. [6] The energy ray curable film-type transparent adhesive according to [4] or [5], wherein the epoxy compound having the epoxycycloalkane structure has two or more of the epoxycycloalkane structures in its molecule. [7] The energy ray curable film-type transparent adhesive according to any one of [3] to [6], wherein the epoxy resin contains an epoxy compound having a hydrogenated bisphenol structure. [8] A device comprising a structure in which components are bonded using the energy ray curable film-type transparent adhesive according to any one of [1] to [7]. [9] A method for manufacturing a device, comprising bonding components using the energy ray curable film-type transparent adhesive according to any one of [1] to [7].

[0009] In this invention, a numerical range represented using "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively.

[0010] The energy-ray curable film-type transparent adhesive of the present invention exhibits excellent transparency in the cured product after the curing reaction, and this transparency can be sustained even at high temperatures. Therefore, by manufacturing a device by bonding components using the energy-ray curable film-type transparent adhesive of the present invention, it becomes possible to more stably extract, for example, the optical functions of the device.

[0011] Figure 1 is a schematic cross-sectional view showing the structure of the film-like adhesive with a release film prepared in the example.

[0012] [Energy Ray Curable Film-Type Transparent Adhesive] The energy ray curable film-type transparent adhesive of the present invention (hereinafter also simply referred to as "the film-type adhesive of the present invention") has a light transmittance T1 (%) of 80.0% or more at a wavelength of 400 nm for the cured product after the curing reaction. In other words, the cured product exhibits sufficiently high transparency after the curing reaction. Furthermore, the light transmittance T1 (%) and the light transmittance T2 (%) of the heat-treated cured product obtained by heat-treating the cured product at 150°C for 100 hours satisfy T1 - T2 ≤ 5%. In other words, even if the cured product after the curing reaction by irradiation with energy rays such as ultraviolet light is exposed to harsh conditions at a temperature significantly higher than the high-temperature environment expected in outdoor or in-vehicle environments where a device containing this cured product may be placed, such as for a long period of 100 hours, the light transmittance does not easily decrease. Therefore, this cured product can maintain high transparency over a long period of time, not only in indoor and low-temperature environments in which devices containing this cured product may be placed, but also when exposed to high temperatures outdoors or inside a vehicle. Film-like adhesives tend to discolor over time in high-temperature environments, and the light transmittance in the entire visible light range can be roughly evaluated using the light transmittance of the obtained cured product at the above wavelength as an indicator. The "light transmittance T1 (%) of the cured product at a wavelength of 400 nm" and the "light transmittance T2 (%) of the heat-treated cured product at a wavelength of 400 nm" as defined in this invention are the parallel light transmittance at a wavelength of 400 nm measured using a spectrophotometer. Specific measurement methods are described in the Examples section below. Furthermore, the "cured product after curing reaction" as defined in this invention refers to a product at 23°C and 1000 mJ / cm². ２This is a cured product obtained as a result of a curing reaction of the film-like adhesive of the present invention by irradiation with ultraviolet light. This ultraviolet irradiation shall be carried out using a mercury lamp. The cured product used for measuring the "light transmittance T1 (%) of the cured product at a wavelength of 400 nm" shall be measured in a state that has not been exposed to a temperature of 50°C or higher after obtaining the cured product by the above curing reaction. Furthermore, this measurement shall be carried out within 30 days after the above curing reaction.

[0013] The film-like adhesive of the present invention is in a pre-curing state, i.e., a B-stage state, and hardens upon irradiation with energy rays to exhibit adhesive strength to the adherend. Therefore, the film-like adhesive of the present invention is a film made of a curable composition. The film-like adhesive of the present invention can be suitably used for bonding and sealing components of devices, and is particularly suitable for bonding and sealing components that require high transparency (e.g., lenses, transparent protective films, glass substrates, the above-mentioned functional elements and functional layers, laminates thereof, etc.). Examples of devices include digital still cameras, digital video cameras, organic EL devices, liquid crystal panel devices, micro-LED devices, smartphones, personal computers, televisions, etc. The film-like adhesive of the present invention is energy-ray curing type and does not require heating for its curing reaction. Examples of this energy ray include light rays such as ultraviolet (UV) rays and ionizing radiation such as electron beams. The energy ray is preferably ultraviolet rays.

[0014] The film-like adhesive of the present invention is energy-ray curable, and there are no particular restrictions on its component composition as long as the cured product satisfies the specified light transmittance requirements of the present invention. Preferably, the film-like adhesive of the present invention comprises an epoxy resin and a photocationic polymerization initiator, and preferably undergoes a curing reaction through chain polymerization of the epoxy resin by the action of energy-ray irradiation and the photocationic polymerization initiator. Furthermore, preferably, the film-like adhesive of the present invention contains a phenoxy resin as a polymer component. In addition to the epoxy resin, phenoxy resin, and photocationic polymerization initiator, the film-like adhesive of the present invention may contain other components described later, to the extent that they do not impair the effects of the present invention.

[0015] The components that may be included in the film-like adhesive of the present invention will be described below.

[0016] <Epoxy Resin> The epoxy resin described above is composed of one or more epoxy compounds. A wide range of epoxy compounds suitable for use as adhesives can be used as this epoxy compound. The epoxy resin that can constitute the film-like adhesive of the present invention undergoes a curing reaction mainly through ring-opening polymerization between epoxy groups, thereby forming a cross-linked structure in the film-like adhesive and resulting in a cured film. In this invention, the terms "epoxy resin" and "epoxy compound" are used interchangeably for convenience to facilitate understanding of the invention. That is, given that the film-like adhesive of the present invention may contain two or more epoxy resins, in this invention, the epoxy resin contained in the film-like adhesive of the present invention is referred to as "epoxy resin" as a whole, and the term "epoxy compound" is used when referring to each of the one or more epoxy resins that constitute this whole "epoxy resin".

[0017] In the present invention, the epoxy compound constituting the epoxy resin is a compound having epoxy groups and an epoxy equivalent of 3000 g / eq or less. In the present invention, the epoxy equivalent of the epoxy compound refers to the number of grams (g / eq) of the epoxy compound containing 1 gram equivalent of epoxy groups. The epoxy equivalent of the epoxy compound constituting the epoxy resin is preferably 50 to 3000 g / eq, more preferably 70 to 1500 g / eq, even more preferably 90 to 1000 g / eq, even more preferably 100 to 500 g / eq, and even more preferably 100 to 400 g / eq.

[0018] The epoxy compound constituting the above epoxy resin preferably does not have an aromatic ring from the viewpoint of further improving the transparency and transparency stability of the cured product. The epoxy compound constituting the above epoxy resin preferably does not have an aromatic ring and has an alicyclic ring. More preferably, the above epoxy resin contains an epoxy compound having an epoxycycloalkane structure. That is, the above epoxy resin preferably consists of an epoxy compound having an epoxycycloalkane structure, and may also contain other epoxy compounds in addition to the epoxy compound having an epoxycycloalkane structure.

[0019] (Epoxy compounds having an epoxycycloalkane structure) The epoxy compounds having the epoxycycloalkane structure described above are compounds having a structure in which two adjacent ring-constituting carbon atoms in the cycloalkane structure are linked by an oxygen atom to form an oxirane ring. The number of ring-constituting carbon atoms in the epoxycycloalkane structure described above is preferably 5 to 8, more preferably 5 or 6, and even more preferably 6. In other words, the epoxycycloalkane structure described above is particularly preferably an epoxycyclohexane structure.

[0020] The epoxy compound having the epoxycycloalkane structure described above preferably has two or more of the epoxycycloalkane structures in its molecule, more preferably 2 to 10, even more preferably 2 to 8, even more preferably 2 to 6, even more preferably 2 to 4, even more preferably 2 or 3, and particularly preferably 2. The epoxy resin described above may contain one or more epoxy compounds having the epoxycycloalkane structure described above.

[0021] A preferred structural formula for the epoxy compound having the epoxycycloalkane structure described above is shown as the following general formula (1).

[0022]

[0023] In general formula (1), n is an integer of 0 to 10, preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, further preferably 1 or 2, and particularly preferably 1. L is an (n+1)-valent linking group (a monovalent group when n is 0). L preferably does not have an aromatic ring. Further, the chemical formula weight of L is preferably 14 to 2000, more preferably 14 to 1000, and still more preferably 14 to 500. L more preferably contains a chain hydrocarbon group (a hydrocarbon group having no cyclic structure). This chain hydrocarbon group may be linear or branched. In addition to the chain hydrocarbon group, L preferably has a group selected from the group consisting of -O-, -S-, -C(=O)-, and -NR- (R represents a hydrogen atom or a substituent, the substituent is preferably an alkyl group, the alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, still more preferably 1 to 4, and further preferably methyl), and more preferably has -C(=O)-O- (an ester bond).

[0024] The compound represented by the above general formula (1) is preferably a compound represented by the following general formula (2).

[0025]

[0026] In the above general formula (2), L １ represents a divalent linking group. L １ more preferably contains an alkylene group. This alkylene group may be linear or branched. L １ in addition to the alkylene group, preferably has a group selected from the group consisting of -O-, -S-, -C(=O)-, and -NR- (R represents a hydrogen atom or a substituent, the substituent is preferably an alkyl group, the alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, still more preferably 1 to 4, and further preferably methyl), and more preferably has -C(=O)-O- (an ester bond).

[0027] Among them, L １ is preferably a group having the following structure. -C(=O)-[O-(CH ２ ) ｐ -C(=O)]] ｑ -O-CH ２- p is preferably an integer between 1 and 12, more preferably an integer between 2 and 10, even more preferably an integer between 3 and 8, and even more preferably an integer between 4 and 6. q is the average number of repetitions, preferably an integer between 0 and 5, more preferably an integer between 0 and 3, even more preferably an integer between 0 and 2, and particularly preferably 0 or 1.

[0028] When the film-like adhesive of the present invention contains an epoxy resin, the proportion of the epoxy compound having the epoxycycloalkane structure in the total epoxy resin is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. It is also preferable that the entire epoxy resin is composed of the epoxy compound having the epoxycycloalkane structure.

[0029] (Other epoxy compounds) Other epoxy compounds that the epoxy resin may contain (epoxy compounds other than epoxy compounds having an epoxycycloalkane structure) include epoxy compounds having a hydrogenated bisphenol structure. The epoxy resin may contain one or more epoxy compounds having a hydrogenated bisphenol structure. The epoxy compound having a hydrogenated bisphenol structure is preferably an epoxy compound having a hydrogenated bisphenol A type structure.

[0030] The epoxy compound constituting the epoxy resin may be a liquid epoxy compound or a solid epoxy compound at normal temperature (23°C). The ratio of liquid to solid epoxy compound can be adjusted in consideration of adhesion to an adherend. It is preferable that at least one of the epoxy compounds constituting the epoxy resin is a liquid epoxy compound, and it is also preferable that all epoxy compounds are liquid. Therefore, when the epoxy resin contains an epoxy compound having an epoxycycloalkane structure, the epoxy compound having an epoxycycloalkane structure is preferably liquid at normal temperature. Further, when the epoxy resin contains an epoxy compound having a hydrogenated bisphenol structure, the epoxy compound having the hydrogenated bisphenol structure is also preferably liquid at normal temperature.

[0031] The weight average molecular weight of the epoxy compound constituting the epoxy resin (each epoxy compound when the epoxy resin contains two or more types of epoxy compounds) is preferably from 100 to 3000, and more preferably from 200 to 1500. The weight average molecular weight is a value measured by GPC (Gel Permeation Chromatography) analysis.

[0032] In the case where the film adhesive of the present invention contains an epoxy resin, the content of the epoxy resin in the solid content (components other than the solvent) of the film adhesive is preferably 10 to 85% by mass, more preferably 20 to 80% by mass, still more preferably 20 to 75% by mass, and even more preferably 22 to 70% by mass.

[0033] <Phenoxy Resin> The film adhesive of the present invention preferably contains at least one phenoxy resin. The phenoxy resin is a component (polymer component, film component) that suppresses film tackiness at normal temperature (23°C) and imparts film-forming properties when the film adhesive is formed. In the present invention, a phenoxy resin refers to a resin having an epoxy equivalent weight (mass of resin per equivalent of epoxy group) exceeding 3000 g / eq. That is, even if a resin has a structure that is characteristic of phenoxy resins, if its epoxy equivalent weight is 3000 g / eq or less, the resin is classified as an epoxy resin.

[0034] Phenoxy resins can be obtained by conventional methods. For example, they can be obtained by the reaction of bisphenol or a biphenol compound with an epihalohydrin such as epichlorohydrin, or by the reaction of a liquid epoxy resin with bisphenol or a biphenol compound.

[0035] The glass transition temperature (Tg) of the above phenoxy resin is preferably 160°C or lower, more preferably 120°C or lower, even more preferably less than 110°C, even more preferably 100°C or lower, and particularly preferably 90°C or lower. The Tg of the phenoxy resin is also preferably 0°C or higher, preferably 10°C or higher, preferably 20°C or higher, may be 30°C or higher, may be 40°C or higher, may be 50°C or higher, may be 60°C or higher, may be 70°C or higher, and may also be 80°C or higher. The Tg of the phenoxy resin is also preferably 0 to 160°C, preferably 10 to 125°C, preferably 30 to 120°C, preferably 50 to 120°C, preferably 70 to 120°C, preferably 80 to 120°C, preferably 80°C or higher and less than 110°C, and also preferably 80 to 100°C. From the viewpoint of increasing the storage modulus of the cured film adhesive of the present invention at room temperature (23°C), the Tg of the phenoxy resin is preferably 80°C or higher. From the viewpoint of further increasing the transparency of the cured film adhesive of the present invention, the Tg of the phenoxy resin is preferably 10 to 120°C, preferably 80 to 120°C, preferably 80°C or higher and less than 110°C, and preferably 80 to 100°C. The above Tg of the phenoxy resin is the peak top temperature of tanδ in dynamic viscoelasticity measurement. Specifically, Tg can be determined as follows: A solution obtained by dissolving the phenoxy resin is applied to a release film, heated and dried to form a film (polymer film) made of phenoxy resin on the release film. The release film is peeled off and removed from this polymer film, and the polymer film is measured using a dynamic viscoelasticity analyzer (product name: Rheogel-E4000F, manufactured by UBM) under the conditions of a measurement temperature range of 20 to 300°C, a heating rate of 5°C / min, and a frequency of 1 Hz. The peak top temperature of the obtained tanδ (the temperature at which tanδ is maximum) is defined as Tg.

[0036] The weight average molecular weight of the phenoxy resin is usually 10,000 or more. Although there is no particular restriction on the upper limit, 5,000,000 or less is practical. The weight average molecular weight of the phenoxy resin is determined in terms of polystyrene by GPC [Gel Permeation Chromatography].

[0037] Focusing on the skeleton of the phenoxy resin, bisphenol A-type phenoxy resins, phenoxy resins containing a biphenyl skeleton and a cyclohexane skeleton, or bisphenol F + 1,6-hexanediol diglycidyl ether-type phenoxy resins can be preferably used in the present invention.

[0038] In the film adhesive of the present invention, the content of the phenoxy resin can be, for example, 30 to 500 parts by mass relative to 100 parts by mass of the epoxy resin, may be 30 to 400 parts by mass, may be 35 to 350 parts by mass, or may be 40 to 300 parts by mass. It is also preferable to set the content of the phenoxy resin to 50 to 250 parts by mass relative to 100 parts by mass of the epoxy resin, more preferably 60 to 200 parts by mass, and still more preferably 65 to 180 parts by mass.

[0039] <Photo-cationic polymerization initiator> In addition to the epoxy resin and the phenoxy resin, the film adhesive of the present invention preferably contains a photo-cationic polymerization initiator. This photo-cationic polymerization initiator is a polymerization initiator that allows the epoxy resin to undergo a chain polymerization reaction when the film adhesive of the present invention is irradiated with energy rays. The photo-cationic polymerization initiator is not particularly limited, and a wide range of conventional photo-cationic polymerization initiators that induce chain polymerization of epoxy resins can be widely used. For example, sulfonium salt-based or iodonium salt-based photo-cationic polymerization initiators can be used. It is known that these initiators can employ various anions as the anions constituting the salt, and for example, those containing antimony, phosphorus, boron, or the like at the anion site are known. A nonionic photo-cationic polymerization initiator can also be used as the photo-cationic polymerization initiator. The photo-cationic polymerization initiator is preferably a UV (ultraviolet) cationic polymerization initiator.

[0040] In the film-like adhesive of the present invention, the content of the photocationic polymerization initiator is not particularly limited as long as it can induce a chain polymerization reaction of the epoxy resin. For example, it can be 0.01 to 30.0 parts by mass, preferably 0.01 to 20.0 parts by mass, more preferably 0.01 to 15.0 parts by mass, even more preferably 0.01 to 10.0 parts by mass, also preferably 0.01 to 8.0 parts by mass, and also preferably 0.01 to 6.0 parts by mass per 100 parts by mass of the epoxy resin. In the film-like adhesive of the present invention, the content of the photocationic polymerization initiator may be 0.05 to 6.0 parts by mass, 0.1 to 5.0 parts by mass, 0.2 to 4.0 parts by mass, or 0.4 to 3.0 parts by mass per 100 parts by mass of the epoxy resin.

[0041] <Other Components> (Silane Coupling Agent) The film adhesive of the present invention may contain a silane coupling agent. By using a silane coupling agent, adhesion to the adherend can be further enhanced, and as a result, adhesive reliability can be improved. The silane coupling agent has at least one hydrolyzable group such as an alkoxy group or an aryloxy group bonded to a silicon atom, and in addition thereto, alkyl groups, alkenyl groups, and aryl groups may be bonded. The alkyl group is preferably substituted with an amino group, an alkoxy group, an epoxy group, or a (meth)acryloyloxy group, and more preferably substituted with an amino group (preferably a phenylamino group), an alkoxy group (preferably a glycidyloxy group), or a (meth)acryloyloxy group. Examples of silane coupling agents include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, and 3-methacryloyloxypropyltriethoxysilane.

[0042] If the film-like adhesive of the present invention contains a silane coupling agent, the amount of silane coupling agent can be 0.1 to 20.0 parts by mass per 100 parts by mass of the epoxy resin, may be 0.5 to 10.0 parts by mass, may be 1.0 to 7.0 parts by mass, may be 1.0 to 5.0 parts by mass, or may be 1.0 to 3.0 parts by mass. It is also preferable that the film-like adhesive of the present invention does not contain a silane coupling agent.

[0043] (Curing retarder) The film adhesive of the present invention may contain a curing retarder. By using a curing retarder, adhesion to the adherend is improved and the adhesive strength is enhanced. As the curing retarder, those commonly used in adhesives can be used. Examples of curing retarders include polyether compounds. Examples of the above polyether compounds include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, calixarene, and crown ether compounds. Among these, crown ether compounds are preferred. Examples of crown ethers include 18-crown-6-ether and 15-crown-5-ether.

[0044] If the film-like adhesive of the present invention contains a curing retarder, the content of the curing retarder can be 0.01 to 20.0 parts by mass per 100 parts by mass of the epoxy resin, may be 0.1 to 10.0 parts by mass, may be 0.1 to 8.0 parts by mass, may be 0.1 to 5.0 parts by mass, and may also be 0.1 to 3.0 parts by mass. It is also preferable that the film-like adhesive of the present invention does not contain a curing retarder.

[0045] (Filler) The film-like adhesive of the present invention may contain a filler to the extent that it does not impair the light transmission properties defined in the present invention. Inorganic fillers are preferred. Examples of inorganic fillers include ceramics such as silica, clay, gypsum, calcium carbonate, barium sulfate, alumina (aluminum oxide), beryllium oxide, magnesium oxide, silicon carbide, silicon nitride, aluminum nitride, and boron nitride; metals or alloys such as aluminum, copper, silver, gold, nickel, chromium, lead, tin, zinc, palladium, and solder; and various inorganic powders such as carbon nanotubes and graphene. The inorganic filler may be surface-treated or surface-modified, and agents used for such surface treatment or surface modification include silane coupling agents, phosphoric acid or phosphoric acid compounds, and surfactants. The shape of the inorganic filler may be flake-like, needle-like, filament-like, spherical, or flaky, but spherical particles are preferred from the viewpoint of high packing and fluidity.

[0046] When the film-like adhesive of the present invention contains a filler, the filler content in the film-like adhesive can be 0.1 to 10.0% by mass, preferably 0.5 to 8.0% by mass, preferably 1.0 to 5.0% by mass, and preferably 1.0 to 3.0% by mass, based on the solid content of the film-like adhesive. Furthermore, from the viewpoint of further improving the transparency of the cured product of the film-like adhesive, the filler content in the film-like adhesive can be 0.1 to 2.5% by mass, preferably 0.1 to 2.0% by mass, preferably 0.2 to 1.5% by mass, and preferably 0.3 to 1.2% by mass, based on the solid content of the film-like adhesive. It is also preferable that the film-like adhesive of the present invention does not contain a filler.

[0047] The film-like adhesive of the present invention may further contain organic solvents, ion trapping agents (ion scavengers), curing catalysts, viscosity modifiers, antioxidants, flame retardants, colorants, etc., to the extent that they do not impair the effects of the present invention. For example, it may contain other additives described in International Publication No. 2017 / 158994.

[0048] When the film-like adhesive of the present invention contains an epoxy resin, a phenoxy resin, and a photocationic polymerization initiator, the total proportion of each of the epoxy resin, phenoxy resin, and photocationic polymerization initiator in the film-like adhesive of the present invention can be, for example, 30% by mass or more, preferably 40% by mass or more, and more preferably 50% by mass or more. This proportion may also be 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 93% by mass or more, or 96% by mass or more.

[0049] The film-like adhesive of the present invention preferably does not contain isocyanate compounds (compounds having isocyanate groups). If isocyanate compounds are included, the crosslinking density of the cured product may increase, making it difficult to impart sufficient flexibility to the film-like cured product. In that case, it may become difficult to apply the film-like adhesive of the present invention to the manufacture of flexible devices and the like. In this regard, with regard to the cured product of the film-like adhesive of the present invention, it is preferable that the cured product does not have urethane bonds. That is, it is preferable that the hydroxyl groups generated by the ring-opening polymerization reaction of epoxy resin, etc., do not react with the isocyanate groups of the isocyanate compound to form urethane bonds.

[0050] Here, in the present invention, "film" means a thin film with a thickness of 200.0 μm or less. The shape, size, etc., are not particularly limited and can be adjusted as appropriate according to the manner of use. The thickness of both the film-like adhesive of the present invention and the cured product obtained by curing this film-like adhesive is usually 1.0 to 100.0 μm, preferably 2.0 to 80.0 μm, more preferably 3.0 to 50.0 μm, even more preferably 3.0 to 40.0 μm, even more preferably 4.0 to 30.0 μm, even more preferably 4.5 to 25.0 μm, and particularly preferably 5.0 to 20.0 μm. The above thickness can be measured by a contact-linear gauge method (tabletop contact-type thickness measuring device).

[0051] The cured film-like adhesive of the present invention preferably has a glass transition temperature (Tg) of 100°C or higher, more preferably 105°C or higher, even more preferably 110°C or higher, and still more preferably 115°C or higher. The preferred range for the Tg of the cured film-like adhesive of the present invention is 100 to 240°C, more preferably 105 to 220°C, even more preferably 110 to 200°C, and still more preferably 115 to 200°C. The Tg of the cured film-like adhesive is the peak top temperature of tanδ in dynamic viscoelasticity measurement. Specifically, Tg can be determined as follows: The film-like adhesive is laminated using a laminator at 70°C until a thickness of 0.1 mm is achieved, and then heated at 23°C with a mercury lamp at a rate of 1000 mJ / cm².２ The curing reaction is induced by ultraviolet irradiation under the specified irradiation conditions. The obtained cured sample is cut into 5 mm wide strips to be used as measurement samples. The measurement samples are measured using a dynamic viscoelasticity measuring device RSAIII (manufactured by TA Instruments) under the following conditions: chuck distance of 20 mm, frequency of 10 Hz, measurement temperature range of -40°C to 250°C, and heating rate of 5°C / min. The peak top temperature of the obtained tanδ (the temperature at which tanδ is maximum) is defined as the Tg of the cured film adhesive. Here, when the Tg of the cured film adhesive of the present invention is X°C, it means that if there are two or more Tg values ​​for the cured product, the lowest temperature Tg is X°C. Therefore, for example, when the Tg of the cured film adhesive of the present invention is 100°C or higher, it means that if there are two or more Tg values ​​for the cured product, the lowest temperature Tg is 100°C or higher.

[0052] As described above, the cured film adhesive of the present invention has a light transmittance T1 (%) at a wavelength of 400 nm of 80.0% or more, preferably 82.0% or more, more preferably 84.0% or more, even more preferably 86.0% or more, even more preferably 88.0% or more, and particularly preferably 90.0% or more. There is no particular upper limit to this light transmittance T1 (%), but it is usually 95.0% or less. Therefore, if we express the light transmittance T1 (%) as a preferred range, it is preferably 82.0 to 95.0%, more preferably 84.0 to 95.0%, even more preferably 86.0 to 95.0%, even more preferably 88.0 to 95.0%, and also preferably 90.0 to 94.0%.

[0053] As described above, the cured film adhesive of the present invention satisfies the following conditions: the light transmittance T1 (%) and the light transmittance T2 (%) at a wavelength of 400 nm of the heat-treated cured product obtained by heat-treating the above cured product at 150°C for 100 hours satisfy T1-T2 ≤ 5.0% (the value obtained by subtracting T2 from T1 is 5.0% or less), more preferably T1-T2 ≤ 4.5%, even more preferably T1-T2 ≤ 4.0%, even more preferably T1-T2 ≤ 3.5%, even more preferably T1-T2 ≤ 3.0%, even more preferably T1-T2 ≤ 2.5%, and even more preferably T1-T2 ≤ 2.0%. The lower limit of T1-T2 is not particularly limited, but is usually 0.1% ≤ T1-T2. If we indicate that T1-T2 is within a preferred range, then 0.1% ≤ T1-T2 ≤ 5.0% is preferred, 0.2% ≤ T1-T2 ≤ 4.5% is also preferred, 0.4% ≤ T1-T2 ≤ 4.0% is also preferred, 0.6% ≤ T1-T2 ≤ 3.5% is also preferred, 0.6% ≤ T1-T2 ≤ 3.0% is also preferred, 0.8% ≤ T1-T2 ≤ 2.5% is also preferred, and 0.8% ≤ T1-T2 ≤ 2.0% is also preferred.

[0054] The film-like adhesive of the present invention can be obtained on a release film or substrate by preparing a composition (varnish) by mixing the constituent components of the film-like adhesive, coating this composition onto a release film or a desired substrate, and drying it as necessary. The composition (varnish) obtained by mixing the constituent components of the adhesive layer usually contains an organic solvent. As for the coating method, a known method can be appropriately employed, for example, a method using a roll knife coater, gravure coater, die coater, reverse coater, etc. Drying only needs to be performed in such a way that the organic solvent is removed without substantially causing a curing reaction and a film-like adhesive is formed, for example, by holding it at a temperature of 80 to 150°C for a short time (for example, about 1 to 20 minutes).

[0055] The film-like adhesive of the present invention is preferably stored in a light-shielded place before use (before the curing reaction) from the viewpoint of suppressing the curing reaction of the film-like adhesive (curing reaction of epoxy resin). The temperature conditions for light-shielded storage are not particularly limited and may be room temperature or refrigerated.

[0056] The film-like adhesive of the present invention can be used for bonding various components in the manufacturing of the devices described later. It can also be used, for example, as a die-attach film in the manufacturing of semiconductor devices (preferably as a die-attach film in a dicing-die-attach film having a laminated structure of a dicing film and a die-attach film).

[0057] [Device Manufacturing Method] The device manufacturing method of the present invention is not particularly limited as long as it is a method of manufacturing a device using the film adhesive of the present invention. One embodiment of the device manufacturing method of the present invention includes bonding components using the film adhesive of the present invention. Therefore, the device of the present invention includes a structure in which components are bonded using the film adhesive of the present invention. The components constituting the device to which the film adhesive of the present invention is applied are not particularly limited. Examples include the protective transparent film in the image sensor described above, the functional elements and functional layers in the image display device described above, and laminates thereof. One embodiment of the device manufacturing method of the present invention includes the step of placing the film adhesive of the present invention on the surface of one component constituting the device, placing another component constituting the device with the film adhesive in between, and curing the film adhesive.

[0058] In the method for manufacturing the device of the present invention, the conditions for the curing reaction described above can be appropriately set considering the constituent components of the film-like adhesive, the heat resistance of the electronic components constituting the device, and so on. For example, using a mercury lamp or the like, at a rate of 100 to 1500 mJ / cm². ２ By irradiating it with ultraviolet light, the adhesive layer can be sufficiently cured.

[0059] The present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to the embodiments of the following examples. Also, MEK is methyl ethyl ketone, PET is polyethylene terephthalate, and UV is ultraviolet light.

[0060] [Preparation of film-like adhesive] A film-like adhesive with a release film, having the layer structure shown in Figure 1, was prepared.

[0061] <Example 1> In a 1000 ml separable flask, 50 parts by mass of an epoxy compound having an epoxycycloalkane structure (trade name: Celoxide 2021P, epoxy equivalent: 126 g / eq, liquid, manufactured by Daicel Corporation, listed as "epoxycycloalkane compound" in the table), 50 parts by mass of phenoxy resin (trade name: 1256, manufactured by Mitsubishi Chemical Corporation), and 30 parts by mass of MEK were added and stirred at 110°C for 2 hours to obtain a resin varnish. Furthermore, this resin varnish was transferred to an 800 ml planetary mixer and a photocatalytic (UV) cationic polymerization initiator (trade name: WPI-116 (iodonium salt type, anionic moiety: SbF) was added. ６ － One part by mass of (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, stirred at room temperature for 1 hour, and then degassed under vacuum to obtain a mixed varnish. The obtained mixed varnish was applied to a surface-release treated PET film with a thickness of 38 μm, heated and dried at 130°C for 10 minutes to obtain a film-like adhesive with a release film, measuring 300 mm in length, 200 mm in width, and with an adhesive layer thickness of 10 μm. Celloxide 2021P is L in the above general formula (2). １ is "-C(=O)-O-CH ２ It has the structure of "-".

[0062] <Examples 2 and 3> Except for changing the ratio (parts by mass) of epoxy resin and phenoxy resin as shown in the table below, a film-like adhesive with a release film, measuring 300 mm in length, 200 mm in width, and with an adhesive layer thickness of 10 μm, was obtained in the same manner as in Example 1.

[0063] <Example 4> An adhesive film with a release film was obtained in the same manner as in Example 1, except that 30 parts by mass of epoxycycloalkane compound and 20 parts by mass of hydrogenated bisphenol A type liquid epoxy resin (product name: ST-3000, epoxy equivalent: 225 g / eq, manufactured by Nippon Steel Chemical & Material Co., Ltd.) were used as the epoxy resin. The adhesive film was 300 mm long, 200 mm wide, and had an adhesive layer thickness of 10 μm.

[0064] <Example 5> A film-like adhesive with a release film, measuring 300 mm in length, 200 mm in width, and with an adhesive layer thickness of 10 μm, was obtained in the same manner as in Example 1, except that 1 part by mass of a silane coupling agent (product name: KBM-403, 3-glycidyloxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the mixed varnish in Example 1.

[0065] <Example 6> A film-like adhesive with a release film, measuring 300 mm in length, 200 mm in width, and with an adhesive layer thickness of 10 μm, was obtained in the same manner as in Example 1, except that 1 part by mass of a curing retarder (18-crown-6-ether, manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the mixed varnish.

[0066] <Comparative Examples 1-7> Except for changing the type and amount of epoxy resin, polymer component, and polymerization initiator as shown in the table below, a film-like adhesive with a release film, measuring 300 mm in length, 200 mm in width, and with an adhesive layer thickness of 10 μm was obtained in the same manner as in Example 1.

[0067] The details of the ingredients in the table below are summarized below. - "Hydrogenated Bisphenol A Liquid Epoxy Compound" Product Name: ST-3000, Epoxy Equivalent: 225 g / eq, Manufactured by Nippon Steel Chemical & Material Co., Ltd. - "Hydrogenated Bisphenol A Solid Epoxy Compound" Product Name: YX8040, Epoxy Equivalent: 1200 g / eq, Manufactured by Mitsubishi Chemical Corporation - "Epoxycycloalkane Compound" Product Name: Celoxide 2021P, Liquid, Epoxy Equivalent: 126 g / eq, Manufactured by Daicel Corporation - "Bisphenol A Liquid Epoxy Compound" Product Name: 828, Epoxy Equivalent: 185 g / eq, Manufactured by Mitsubishi Chemical Corporation - "Epoxy-modified Polybutadiene" Product Name: Epolid PB4700, Epoxy Equivalent: 165 g / eq, Manufactured by Daicel Corporation - "Acrylic Monomer" Tripropylene Glycol Diacrylate (TPGDA), Manufactured by Daicel Ornex Co., Ltd. - "Phenoxy Resin" Product name: 1256, Bisphenol A type, manufactured by Mitsubishi Chemical Corporation, "Acrylic resin" Product name: SG-708-6, Tg: 5℃, manufactured by Nagase ChemteX Corporation, "Photocationic polymerization initiator" Product name: WPI-116 (Iodonium salt type, Anion moiety: SbF ６ － ), Fujifilm Wako Pure Chemical Industries Ltd. - "Photoradical polymerization initiator" Product name: Irgacure 184, IGM Resins B.V. - "Silane coupling agent" Product name: KBM-403, 3-glycidyloxypropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd. - "Curing retarder" 18-crown-6-ether, Tokyo Chemical Industries Ltd.

[0068] <Measurement of Light Transmittance T1 (%)> The film-like adhesive with release film obtained in each example and comparative example was cut into a 5 cm x 5 cm square to be used as a measurement sample. A mercury lamp (product name: UVL-2000RS, manufactured by Ushio Inc.) was used to measure this sample at 23°C, at a rate of 1000 mJ / cm². ２UV light was irradiated from the opposite side of the release film to obtain a film-like cured material. Next, the release film was peeled off, and the parallel light transmittance of the cured material was measured using a spectrophotometer (Shimadzu Corporation, UV-Vis spectrophotometer UV-1800) to determine the parallel light transmittance at a wavelength of 400 nm. This measurement was performed using the transmittance of air as a baseline.

[0069] <Measurement of Light Transmittance T2 (%)> The cured material whose light transmittance T1 (%) was measured was subjected to heat treatment at 150°C for 100 hours. The parallel light transmittance at a wavelength of 400 nm was determined for the cured material after heat treatment in the same manner as above.

[0070] <Measurement of Tg of Cured Product> The release film was peeled off from the film-like adhesive with release film obtained in each example and comparative example, and the film-like adhesive was laminated using a laminator at 70°C until a thickness of 0.1 mm was obtained to obtain a laminated sample. This laminated sample was heated at 23°C using a mercury lamp (product name: UVL-2000RS, manufactured by Ushio Inc.) at a concentration of 1000 mJ / cm². ２ A cured material was obtained by irradiating it with UV light. This cured material was cut into 5 mm wide strips to be used as measurement samples. Using a measurement device RSAIII (manufactured by TA Instruments), the viscoelastic behavior of each measurement sample was measured under tensile conditions of a chuck distance of 20 mm and a frequency of 10 Hz, when heated from -40°C to 250°C at a heating rate of 5°C / min, and Tg was determined. Tg was defined as the temperature at which the maximum value of tanδ was observed. If there were two or more maximum values, the temperature at which the lower temperature maximum value was observed was defined as Tg.

[0071] <Visibility Test> (Preparation of Test Samples) A ​​silicone chip (size: 10 mm x 10 mm, thickness: 350 μm) having an L-shaped alignment mark (100 μm per side) on its surface was coated with the transparent adhesive film with release film obtained in each example and comparative example, with the side opposite the release film facing the silicone chip, using a hand roller on a 70°C stage. The excess adhesive film was then cut and separated along the periphery of the silicone chip, and 1000 mJ / cm was applied from the release film side using a mercury lamp (product name: UVL-2000RS, manufactured by Ushio Inc.). ２The film-like transparent adhesive was cured by irradiation with UV light. In this way, a test sample was obtained in which the film-like cured material and the release film were laminated in that order on the alignment mark surface of the silicon chip. Twenty test samples were prepared for each example and comparative example of the film-like transparent adhesive with release film, and 10 of these were subjected to heat treatment in air at 150°C for 100 hours.

[0072] (Visibility Test Method) For each of the 10 test samples that had not undergone the above heat treatment (unheat-treated samples) and 10 test samples that had undergone the above heat treatment (heat-treated samples), the release film was peeled off the test samples. Next, dicing tape (product name: K-13, manufactured by Furukawa Electric Co., Ltd.) was attached to the side of the test sample opposite to the film-like cured material, and the test sample was fixed to a dicing frame (product name: DTF2-8-1H001, manufactured by DISCO). Next, using a die bonder (product name: DB-800, manufactured by Hitachi High-Technologies Corporation), with the brightness fixed at 60%, the number of samples in which the alignment marks on the chip surface covered with the cured material could be recognized (visible number) was determined for the 10 unheat-treated samples and the 10 heat-treated samples, respectively.

[0073]

[0074] As shown in the table above, even if the light transmittance T1 (%) of the cured product obtained by the curing reaction is 80.0% or higher, the film-like adhesives of Comparative Examples 1, 2, 4, 6, and 7, which do not satisfy T1-T2 ≤ 5%, show reduced transparency when the cured product is subjected to prolonged heat treatment at a high temperature of 150°C, resulting in a smaller number of visible samples. Furthermore, Comparative Examples 3 and 5, whose cured product light transmittance T1 (%) does not meet the requirement of 80% or higher, show a small number of visible samples even without heat treatment. In contrast, the film-like adhesives of Examples 1 to 6, whose cured product light transmittance T1 (%) is 80.0% or higher and which satisfy T1-T2 ≤ 5%, showed a large number of visible samples regardless of whether heat treatment was performed or not. The present invention has succeeded in creating and completing a curable film-like transparent adhesive that achieves transparency or transparency stability that could not be achieved with the prior art.

[0075] Although we have described the present invention along with its embodiments, we do not intend to limit our invention in any detail of the description unless specifically designated, and we believe that it should be interpreted broadly without contradicting the spirit and scope of the invention as set forth in the appended claims.

[0076] This application claims priority based on Japanese Patent Application No. 2025-051012, filed in Japan on 26 March 2025, the contents of which are incorporated herein by reference as part of this specification.

[0077] 1. Film-type adhesive 2. Substrate (support substrate, release film)

Claims

1. An energy-ray curable film-type transparent adhesive, wherein the cured product after the curing reaction has a light transmittance T1 (%) at a wavelength of 400 nm of 80.0% or more, and the light transmittance T1 and the light transmittance T2 (%) at a wavelength of 400 nm of a heat-treated cured product obtained by heat-treating the cured product at 150°C for 100 hours satisfy T1 - T2 ≤ 5%.

2. The energy ray curable film-type transparent adhesive according to claim 1, wherein the glass transition temperature of the cured product is 100°C or higher.

3. The energy ray-curable film-like transparent adhesive according to claim 2, wherein the energy ray-curable film-like transparent adhesive contains an epoxy resin, a phenoxy resin, and a photocationic polymerization initiator.

4. The energy ray curable film-like transparent adhesive according to claim 3, wherein the epoxy resin comprises an epoxy compound having an epoxycycloalkane structure.

5. The energy ray curable film-like transparent adhesive according to claim 4, wherein the number of ring constituent carbon atoms in the epoxycycloalkane structure is 5 to 8.

6. The energy ray curable film-like transparent adhesive according to claim 5, wherein the epoxy compound having the epoxycycloalkane structure has two or more of the epoxycycloalkane structures in its molecule.

7. The energy ray curable film-like transparent adhesive according to claim 6, wherein the epoxy resin comprises an epoxy compound having a hydrogenated bisphenol structure.

8. A device comprising a structure in which components are bonded together using an energy ray curable film-like transparent adhesive as described in any one of claims 1 to 7.

9. A method for manufacturing a device, comprising bonding components using an energy ray-curable film-like transparent adhesive as described in any one of claims 1 to 7.

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