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

Abstract

An energy-ray-curable film-shaped transparent adhesive which, through a curing reaction, gives a cured object having a haze H1 of 9.0% or less, the cured object, when heat-treated at 150°C for 100 hours, giving a heat-treated cured object having a haze H2, the haze H2 and said haze H1 satisfying H2-H1≤5%; a device obtained using the adhesive; and a method for producing the 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 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 a 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 the haze value H1 of the cured product after the curing reaction is 9.0% or less, and the haze value H2 of the heat-treated cured product obtained by heat-treating the cured product at 150°C for 100 hours and the haze value H1 satisfy H2 - H1 ≤ 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 higher. [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 of 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] The energy ray-curable film-type transparent adhesive according to any one of [3] to [7], wherein the energy ray-curable film-type transparent adhesive contains a silane coupling agent. [9] A device having a structure in which components are bonded using the energy ray-curable film-type transparent adhesive according to any one of [1] to [8].

[10] 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 [8].

[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 haze value H1 of 9.0% or less after the curing reaction. In other words, after the curing reaction, the cured product exhibits sufficiently high transparency. Furthermore, the haze value H2 of the heat-treated cured product obtained by heat-treating the cured product at 150°C for 100 hours satisfies H2 - H1 ≤ 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 of a much higher temperature (150°C) for a long period of time of 100 hours than the high-temperature environment expected in outdoor or vehicle interiors where a device containing this cured product may be placed, the transparency does not easily deteriorate. Therefore, this cured product can maintain high transparency for a long period of time, not only in indoor and low-temperature environments where a device containing this cured product may be placed, but also when exposed to high temperatures outdoors or in vehicle interiors.

[0013] The "haze value H1 of the cured product" and the "haze value H2 of the heat-treated cured product" as defined in this invention are haze values ​​under a D65 light source and can be measured using a haze meter. Specific measurement methods are described in the Examples section below. Furthermore, the "cured product after the curing reaction" as defined in this invention refers to a product with a haze value of 1000 mJ / cm² at 23°C. ２This is a cured product obtained as a result of a curing reaction of the film-like adhesive of the present invention by ultraviolet irradiation. This ultraviolet irradiation shall be carried out using a mercury lamp. The cured product used for measuring the "haze value H1 of the cured product" above shall be one that has not been exposed to temperatures 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.

[0014] 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.

[0015] 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 haze value specified in the present invention. Preferably, the film-like adhesive of the present invention comprises an epoxy resin and a photocationic polymerization initiator, and preferably the epoxy resin undergoes chain polymerization and curing reaction through the action of energy-ray irradiation and the photocationic polymerization initiator. Furthermore, it is preferable that 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.

[0016] The components that may be included in the film-like adhesive of the present invention will be described below.

[0017] <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".

[0018] 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.

[0019] 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.

[0020] (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.

[0021] 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.

[0022] A preferred structural formula for the epoxy compound having the epoxycycloalkane structure described above is shown as the following general formula (1).

[0023]

[0024] 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 -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 a -C(=O)-O- (ester bond).

[0025] The compound represented by general formula (1) above is preferably a compound represented by the following general formula (2).

[0026]

[0027] In general formula (2) above, L １ represents a divalent linking group. L １ more preferably contains an alkylene group. This alkylene group may be linear or branched. In addition to the alkylene group, L １ preferably has a group selected from -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 a -C(=O)-O- (ester bond).

[0028] Among these, 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.

[0029] 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.

[0030] (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.

[0031] The epoxy compound constituting the epoxy resin may be either an epoxy compound that is liquid at ordinary temperature (23°C) or a solid epoxy compound. 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 of the epoxy compounds are liquid. Therefore, when the epoxy resin contains an epoxy compound having an epoxycycloalkane structure, the epoxy compound having the epoxycycloalkane structure is preferably liquid at ordinary temperature. Furthermore, 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 ordinary temperature.

[0032] 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 obtained by GPC (Gel Permeation Chromatography) analysis.

[0033] When 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.

[0034] <Phenoxy Resin> The film adhesive of the present invention preferably contains at least one phenoxy resin. Phenoxy resin is a component (polymer component, film component) that suppresses film tackiness at ordinary temperature (23°C) and imparts film-forming properties when a film adhesive is formed. In the present invention, a phenoxy resin is a resin having an epoxy equivalent (mass of resin per 1 equivalent of epoxy group) exceeding 3000 g / eq. That is, even if a resin has a phenoxy resin structure, a resin having an epoxy equivalent of 3000 g / eq or less is classified as an epoxy resin.

[0035] 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.

[0036] 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 obtained tanδ peak top temperature (the temperature at which tanδ is maximum) is defined as Tg.

[0037] The weight average molecular weight of the above phenoxy resin is usually 10,000 or more. Although there is no particular restriction on the upper limit, an upper limit of 5,000,000 or less is practical. The weight average molecular weight of the above phenoxy resin is determined in terms of polystyrene by GPC [Gel Permeation Chromatography].

[0038] Focusing on the skeleton of the phenoxy resin, in the present invention, 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.

[0039] In the film adhesive of the present invention, the content of the above phenoxy resin can be, for example, 30 to 500 parts by mass relative to 100 parts by mass of the above 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 above phenoxy resin to 50 to 250 parts by mass, more preferably 60 to 200 parts by mass, and still more preferably 65 to 180 parts by mass, relative to 100 parts by mass of the above epoxy resin.

[0040] <Photo-cationic polymerization initiator> In addition to the above epoxy resin and 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 for causing a chain polymerization reaction of the epoxy resin when the film adhesive of the present invention is irradiated with energy rays. The above 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 used. For example, sulfonium salt-based or iodonium salt-based photo-cationic polymerization initiators can be used. It is known that these initiators can adopt 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 non-ionic photo-cationic polymerization initiator can also be used as the above photo-cationic polymerization initiator. The photo-cationic polymerization initiator is preferably a UV (ultraviolet) cationic polymerization initiator.

[0041] In the film-like adhesive of the present invention, the content of the photocationic polymerization initiator 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. In the film-like adhesive of the present invention, the content of the photocationic polymerization initiator can 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.

[0042] <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. Furthermore, a small amount of silane coupling agent can exhibit an adhesion-improving effect without substantially affecting the transparency of the cured product. 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, alkyl groups, alkenyl groups, and aryl groups may be bonded. The alkyl group is preferably substituted with an amino group, alkoxy group, epoxy group, or (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.

[0043] 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.

[0044] The film-like adhesive of the present invention may further contain organic solvents, ion trapping agents, curing catalysts, viscosity modifiers, antioxidants, flame retardants, colorants, curing retardants, fillers, 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.

[0045] 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.

[0046] 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. For example, it is preferable that 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.

[0047] 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).

[0048] 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. ２The 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 obtained tanδ peak top temperature (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.

[0049] As described above, the cured film-like adhesive of the present invention has a haze value H1 of 9.0% or less, preferably 8.0% or less, more preferably 6.0% or less, even more preferably 5.0% or less, even more preferably 4.0% or less, even more preferably 3.0% or less, and particularly preferably 2.5% or less. The lower limit of this haze value H1 is not particularly limited, but is usually 0.1% or more, 0.3% or more is practical, it may also be 0.6% or more, or 1.0% or more. Therefore, as a preferred range for the haze value H1, it is preferably 0.1 to 9.0%, more preferably 0.1 to 8.0%, even more preferably 0.3 to 6.0%, also preferably 0.3 to 5.0%, also preferably 0.3 to 4.0%, also preferably 0.6 to 3.0%, also preferably 1.0 to 2.5%, and also preferably 1.2 to 2.3%.

[0050] As described above, the cured film adhesive of the present invention has a haze value H2 and a haze value H1 of the heat-treated cured product obtained by heat-treating the cured product at 150°C for 100 hours, and it is more preferable that H2-H1 ≤ 5% (the value obtained by subtracting H1 from H2 is 5% or less), H2-H1 ≤ 4.5%, even more preferably H2-H1 ≤ 4.0%, even more preferably H2-H1 ≤ 3.5%, even more preferably H2-H1 ≤ 3.0%, even more preferably H2-H1 ≤ 2.5%, and even more preferably H2-H1 ≤ 2.0%. The lower limit of H2-H1 is not particularly limited, but it is usually 0.1% ≤ H2-H1. If we indicate that H2-H1 is within a preferred range, then 0.1% ≤ H2-H1 ≤ 5.0% is preferred, 0.2% ≤ H2-H1 ≤ 4.5% is also preferred, 0.4% ≤ H2-H1 ≤ 4.0% is also preferred, 0.6% ≤ H2-H1 ≤ 3.5% is also preferred, 0.6% ≤ H2-H1 ≤ 3.0% is also preferred, 0.8% ≤ H2-H1 ≤ 2.5% is also preferred, and 0.8% ≤ H2-H1 ≤ 2.0% is also preferred.

[0051] 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).

[0052] 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.

[0053] 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).

[0054] [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.

[0055] 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.

[0056] 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.

[0057] [Preparation of film-like adhesive] A film-like adhesive with a release film, having the layer structure shown in Figure 1, was prepared.

[0058] <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 － ), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 1 part by mass of a silane coupling agent (product name: KBM-403, 3-glycidyloxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., 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 "-".

[0059] <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.

[0060] <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.

[0061] <Comparative Examples 1-8> Except for changing the types and amounts of components used in Example 1 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.

[0062] 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. - "Filler" Product name: FB-5SDC, Silica filler slurry, d50: 4.1 μm, Admatex Co., Ltd.

[0063] <Measurement of Haze Value H1> 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 concentration of 1000 mJ / cm². ２ UV 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 haze value under the D65 light source was measured using a haze meter (model: HZ-V3, manufactured by Suga Test Instruments Co., Ltd.). This measurement was performed using the haze value of air as the baseline.

[0064] <Measurement of Haze Value H2> The cured material for which the haze value H1 was measured was subjected to heat treatment at 150°C for 100 hours. The haze value of the cured material after heat treatment was measured in the same manner as above.

[0065] <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.

[0066] <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.). ２ The 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.

[0067] (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.

[0068] The results above are summarized in the table below.

[0069]

[0070] As shown in the table above, even if the haze value H1 of the cured product obtained by the curing reaction is 9.0% or less, the film-like adhesives of Comparative Examples 1, 2, 4, 7, and 8, which do not satisfy H2-H1≦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, 5, and 6, which do not satisfy the haze value H1 of the cured product being 9.0% or less, also show a small number of visible samples even without heat treatment. In contrast, the film-like adhesives of Examples 1 to 4, which have a haze value H1 of 9.0% or less and satisfy H2-H1≦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.

[0071] 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.

[0072] This application claims priority under Japanese Patent Application No. 2025-051013, filed in Japan on 26 March 2025, the contents of which are incorporated herein by reference as part of this specification.

[0073] 1. Film-type adhesive 2. Substrate (support substrate, release film)

Claims

1. An energy-ray curable film-type transparent adhesive, wherein the haze value H1 of the cured product after the curing reaction is 9.0% or less, and the haze value H2 of the heat-treated cured product obtained by heat-treating the cured product at 150°C for 100 hours, and the haze value H1 satisfy H2 - H1 ≤ 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. The energy ray-curable film-like transparent adhesive according to claim 4, wherein the energy ray-curable film-like transparent adhesive contains a silane coupling agent.

9. 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 8.

10. 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 8.

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