Thermal radical polymerizable dry films and electronic devices

Abstract

This invention provides a dry film with excellent optical properties, sealing ability, low-temperature curing properties, cured appearance, storage stability, and handling characteristics. [Solution] The problem is solved by a heat-radical polymerizable dry film 11 containing a radical polymerizable organic compound and a peroxide-based thermal radical polymerization initiator, wherein the peroxide-based thermal radical polymerization initiator has a 10-hour half-life temperature of 60 to 120°C, and the film contains 95% by mass or more of a radical polymerizable polymer (a) with a Tg of -50 to 90°C in 100% by mass of the radical polymerizable organic compound, the radical polymerizable polymer (a) includes a radical polymerizable acrylic polymer, and the loss loss tangent (tanδ80) at 80°C obtained by dynamic viscoelasticity measurement is 0.3 to 0.7.

Description

[Technical Field]

[0001] This disclosure relates to electronic devices comprising a thermal radical polymerizable dry film and a cured product thereof. [Background technology]

[0002] Dry films are used as encapsulants for semiconductor devices. In particular, dry films with excellent processability and optical properties are required for use as partitions in optical sensor modules and as materials placed around each RGB light-emitting element in LED displays. For example, Reference 1 discloses a dry film formed from a curable composition having a viscosity suitable for inkjet printing, comprising a specific photopolymerization initiator and a specific polymerization inhibitor. Conventionally, a known method for encapsulating LEDs involves embedding a dry film in a region where multiple LEDs are arranged by heat pressing or the like, and curing the dry film by ultraviolet irradiation. Reference 2 also discloses a light-shielding dry film composed of a polymer resin with a specific glass transition temperature and a specific weight-average molecular weight, an epoxy resin, and carbon black. Furthermore, Reference 3 discloses an encapsulation film having 50 to 100% by mass of a block copolymer having 10 to 90% by mass of liquid crystalline polyester segments (A) and amorphous vinyl polymer segments (B). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-110251 [Patent Document 2] Japanese Patent Publication No. 2022-22562 [Patent Document 3] Japanese Patent Publication No. 2009-114423 [Overview of the project] [Problems that the invention aims to solve]

[0004] In recent years, micro-LEDs have been undergoing extensive development. These LEDs have narrow spacings of 10 to 250 μm, and it is necessary to seal these tiny grooves without any gaps. However, conventional dry films cannot adequately fill the spaces between the grooves, resulting in voids (also known as poor sealing). The cured dry film after sealing is required to maintain high transparency for a long period of time in order to not impair the brightness of the micro-LED elements. On the other hand, in applications that suppress color mixing of adjacent light-emitting elements, excellent optical properties such as high light shielding are required. Furthermore, dry films that cure quickly at low temperatures are in demand (also known as low-temperature curing films) from the perspective of reducing thermal damage to components, shortening the sealing process time, or suppressing partial deformation or poor adhesion of the sealing layer caused by thermal shrinkage of the protective film during the curing process. Furthermore, from the perspective of the appearance after curing, suppression of foaming during the curing process is required. In addition, since the sealing performance deteriorates if the hardening reaction progresses during long-term storage, it is required that the sealing performance remains stable even after long-term storage, just as it was before storage (also known as storage stability). Furthermore, there is a demand for dry films that are easy to handle during work and do not have surface tack (also known as ease of handling). Therefore, the object of this disclosure is to provide a dry film that is excellent in optical properties, sealing ability, low-temperature curing ability, appearance after curing, storage stability, and handling. [Means for solving the problem]

[0005] As a result of diligent research to solve the above problems, the present inventors have found that a thermally radical polymerizable dry film containing a radically polymerizable organic compound and a thermally radical polymerization initiator, wherein the 10-hour half-life temperature of the thermally radical polymerization initiator is 60°C or higher and 120°C or lower, results in a thermally radical polymerizable dry film with excellent optical properties, sealing properties, low-temperature curing properties, appearance after curing, storage stability, and handling properties, leading to the present disclosure below.

[0006] [1]: A dry film used for forming a sealing layer by filling the gaps between multiple microLEDs formed on a substrate, It contains a radically polymerizable organic compound and a peroxide-based thermal radical polymerization initiator. The peroxide-based thermal radical polymerization initiator has a 10-hour half-life temperature of 60°C or higher and 120°C or lower. The radical polymerizable organic compound contains 95% by mass or more of a radical polymerizable polymer (a) having a glass transition temperature of -50°C or higher and 90°C or lower, Radical polymerizable polymer (a) includes a radical polymerizable acrylic polymer, A thermally radical-polymerizable dry film having a loss tangent (tanδ80) of 0.3 to 0.7 at 80°C, obtained by dynamic viscoelasticity measurement. [2]: The storage modulus at 80°C (G'80) obtained by dynamic viscoelasticity measurement is 5 × 10 4 Pa~5×10 7 The thermal radical polymerizable dry film according to [1], characterized in that it is Pa. [3]: A heat radical polymerizable dry film according to [1] or [2], wherein the coefficient of dynamic friction of the surface of the dry film is 0.5 or less. [4]: A heat radical polymerizable dry film according to any of [1] to [3], having a thickness of 0.5 to 100 μm. [5]: A thermal radical polymerizable dry film according to any one of [1] to [4], wherein the 10-hour half-life temperature of the peroxide-based thermal radical polymerization initiator is 80°C or higher and 110°C or lower. [6]: The amount of the peroxide-based thermal radical polymerization initiator blended is 0.01 to 20% by mass of the total solids, according to any one of [1] to [5]. [7]: An electronic device comprising a cured product of a thermal radical polymerizable dry film as described in any of [1] to [6]. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a thermally radical polymerizable dry film, a cured product, and an electronic component that are excellent in optical properties, sealing properties, low-temperature curability, appearance after curing, storage stability, and handling properties.

Brief Description of the Drawings

[0008] [Figure 1] A schematic cross-sectional view schematically showing an embodiment of the thermally radical polymerizable dry film of the present disclosure. [Figure 2] A schematic cross-sectional view showing a step of filling a dry film on a substrate having a plurality of micro LEDs. [Figure 3] A schematic cross-sectional view schematically showing a test substrate used for sealing property evaluation. [Figure 4] A schematic cross-sectional view for explaining a method of evaluating the appearance after curing.

Modes for Carrying Out the Invention

[0009] Hereinafter, the thermally radical polymerizable dry film of the present disclosure will be described more specifically. Note that the embodiments described below illustrate an example of the present disclosure. The present disclosure is not limited to the following embodiments, and also includes modified examples implemented within the scope of not changing the gist of the present disclosure. <00​​​​Figure 1 is a schematic cross-sectional view of a laminate including a thermally radical polymerizable dry film 11 according to one embodiment of the present disclosure. The laminate shown in Figure 1(a) is a two-layer laminate in which the thermally radical polymerizable dry film 11 and a release liner 12 are laminated. As shown in Figure 1(b), a protective film 13 may be formed on the side of the thermally radical polymerizable dry film 11 opposite to the side on which the release liner 12 is laminated. The laminate may optionally have other layers between the thermally radical polymerizable dry film 11 and the release liner 12 or protective film 13. Furthermore, the thermally radical polymerizable dry film of the present disclosure is single-layer or multi-layer. The multi-layer configuration may be a laminate in which multiple thermally radical polymerizable dry films of the same or different types are laminated, or a laminate in which the thermally radical polymerizable dry film of the present disclosure is laminated with other layers without departing from the spirit of the present disclosure.

[0011] The thermal radical polymerizable dry film of this disclosure is preferably used to encapsulate optical semiconductor elements. In particular, a form used to form an encapsulation layer for multiple optical semiconductor elements used as a light source for a display is preferred. The encapsulation layer may be used as a highly transparent encapsulation layer that does not impair the brightness of the semiconductor element, as well as as a reflective layer that reflects light, a high refractive index layer, or a light-shielding layer. Examples of displays using multiple optical semiconductor elements as light sources include organic EL display panels, liquid crystal display panels, micro-LED display panels, plasma display panels, and electronic paper, which are displays that require high quality. Organic EL light-emitting elements, LED semiconductor elements, and micro-LED semiconductor elements are preferred as optical semiconductor elements. Hereinafter, the thermal radical polymerizable dry film of this disclosure may be abbreviated as "dry film".

[0012] Dry film is suitable for applications in which a sealing layer is formed by filling the gaps between multiple microLEDs formed on a substrate all at once. It is preferable to laminate the film in direct contact with the adherend. Examples of adherends include substrates on which the aforementioned multiple optical semiconductor elements (microLEDs) are formed, as well as substrates having substrate electrode portions made of metal, backlight modules, and substrates having multiple optical semiconductor element portions such as organic EL. Examples of the substrate include acrylic, polycarbonate, epoxy, polyimide, glass, glass epoxy, ITO, or polyethylene terephthalate. Because dry film has high conformability to uneven surfaces, it is suitable for use in filling the spaces between multiple optical semiconductor elements. By filling the spaces between optical semiconductor elements with dry film and curing it, the cured dry film functions as a sealing layer that fixes the optical semiconductor elements to the substrate.

[0013] By using a heat-radical polymerizable dry film containing a white inorganic filler and surrounding the side surfaces of individual micro-LEDs with the cured product of the dry film, the light emitted from each micro-LED can be reflected, suppressing a decrease in brightness or improving brightness. Furthermore, by using a heat-radical polymerizable dry film containing a colorant and filling the spaces between individual micro-LEDs with the cured product of the dry film, a partition, i.e., a light-shielding layer, can be created to prevent the mixing of light emitted from adjacent micro-LEDs. Since the dry film can conform to micro-sized optical semiconductor elements, micro-LEDs are particularly suitable as optical semiconductor elements. Below, an example of the process for forming the sealing layer will be explained using Figure 2.

[0014] Process (a): Dry film placement process As shown in Figure 2(a) as an example, a dry film 11 is placed on a substrate 21 having a plurality of optical semiconductor elements 20. It is preferable to place the dry film 11 directly over the optical semiconductor elements 20. If a release liner is present, it may be peeled off immediately after placement, or after the pressing process described below. In this specification, the term "multiple optical semiconductor elements" is not particularly limited to two or more optical semiconductor elements. Furthermore, the emission color of the optical semiconductor elements is not particularly limited and examples include red, green, and blue. The size of the optical semiconductor device is such that its thickness is 100 μm or less and its planar area is 40,000 μm². 2 The following are preferred: a thickness of 50 μm or less and a planar area of ​​10,000 μm². 2 The following are more preferable: a thickness of 20 μm or less and a planar area of ​​2,500 μm². 2 The following are even more preferable. The spacing between optical semiconductor elements mounted on the substrate is, for example, 10 to 5,000 μm. When red, green, and blue optical semiconductor elements are mounted on the substrate as a set of 1 pixel, the spacing between pixels is, for example, 10 to 2,000 μm, preferably 20 to 1,800 μm, and more preferably 500 to 1,500 μm. The spacing between optical semiconductor elements within a single pixel is, for example, 10 to 250 μm, preferably 10 to 100 μm, and more preferably 20 to 60 μm.

[0015] Process (b): Pressing process As shown in Figure 2(b), the dry film 11 is fluidized by pressing and filled between multiple optical semiconductor elements 20. The dry film filled between the multiple optical semiconductor elements 20 undergoes thermal curing to become a cured product 11'. The cured product 11' functions as a sealing layer covering the substrate 21 and the optical semiconductor elements. The pressing method is not particularly limited, but hot pressing and vacuum pressing are preferred. From the viewpoint of the dry film's filling properties, the pressing temperature is preferably 20 to 200°C, more preferably 50 to 150°C, even more preferably 60 to 130°C, and particularly preferably 80 to 120°C.

[0016] To improve adhesion between the optoelectronic element and the substrate, further heating and aging may be performed after pressing. The heating temperature is preferably 80 to 250°C, and more preferably 100 to 220°C. The heating time is preferably 30 to 300 minutes, more preferably 60 to 240 minutes, and even more preferably 90 to 180 minutes. By using the above heating temperature and time, residual stress in the dry film can be removed, the adhesion surface can be smoothed, and the thermal curing of the dry film forming the sealing layer can be promoted. After the pressing and heating aging processes described above, the heat-radical polymerizable dry film undergoes thermal curing, becoming a cured dry film (also called a cured product). Curing improves the toughness and durability of the sealing layer and increases its adhesion to the substrate. Furthermore, if necessary, step (c) described later may be performed. Heat aging may be performed after step (c) described later.

[0017] Process (c): Etching process In step (c), etching is performed to remove or thin the cured dry film on the optical semiconductor device. Removing the cured dry film increases the brightness of the light-emitting element and ensures visibility when it emits light. The thickness of the sealing layer after etching is preferably about the same as the thickness of the optical semiconductor device, as shown in Figure 2(c-1), or less than or equal to the thickness of the dry film, as shown in Figure 2(c-2). It is not necessary to completely remove the dry film from the light-emitting element; it is sufficient if it is substantially removed, and a small thin film may remain. Furthermore, if the brightness of the light-emitting element is sufficiently ensured, the etching step may not be performed. The etching method is not particularly limited, but preferred examples include wet etching methods such as chemical polishing using chemical agents, physical polishing using abrasives, laser etching, plasma etching using argon plasma or oxygen plasma, and dry etching methods such as ion beam etching. From the viewpoint of reducing surface irregularities, it is preferable to use a combination of wet etching and dry etching methods. Physical etching such as plasma treatment may also be used. As the etching conditions, for example, in an anisotropic plasma apparatus, a mixed gas of CF4 / O2 / N2 may be used for dry etching under the conditions of an output of 1500 to 3000 W and 180 to 600 seconds. At this time, the gas supply amount of CF4 may be, for example, 50 to 100 sccm, the gas supply amount of O2 may be, for example, 500 to 1000 sccm, and the gas supply amount of N2 may be, for example, 50 to 100 sccm.

[0018] <Dry film> The dry film contains a radically polymerizable organic compound and a thermal radical polymerization initiator. The thickness of the dry film is preferably, for example, 0.5 to 100 μm, and more preferably 1 to 50 μm. By being in this range, the dry film has excellent sealing properties. The dry film may be a single layer or a laminate of two or more layers, and the thickness can be measured by the method described in the examples below. The dry film is required to have various optical properties according to its use. For example, in the case of applications where high transparency is required, high transparency can be achieved by not using a colorant. In addition, in the case of applications where light shielding properties are required, light shielding properties can be imparted by using a black colorant. In addition, in the case of applications where reflectivity is required, reflectivity can be imparted by using a white colorant. In addition, in the case of applications where a high refractive index is required, the refractive index can be changed to a high refractive index by using an inorganic filler having a high refractive index. The optical properties can be measured by the method described in the examples below.

[0019] The storage modulus (G’80) at 80°C obtained by measuring the dynamic viscoelasticity of the dry film is 5×10 4 Pa to 5×10 7 Pa is preferable, 10×10 4 Pa to 1×10 7 Pa is more preferable, 50×10 4 Pa to 5×10 6 Pa is even more preferable. G’80 is 5×10 4By setting the pressure to Pa or higher, the pressure applied to the dry film during the encapsulation press process of the optoelectronic semiconductor device is more easily diffused uniformly, and G'80 is set to 5 × 10 7 By setting the pressure to Pa or less, the optoelectronic element can be more easily followed and adhered to, resulting in excellent sealing of the optoelectronic element. G'80 is a value measured in shear mode under conditions of 1 Hz to 10 Hz and can be measured by the method described in the examples below. By adjusting G'80 to the above range, the dry film can exhibit excellent fluidity during the pressing process.

[0020] Furthermore, the G'80 of this disclosure can be adjusted by the type, composition, and content of the radical polymerizable organic compound and the content of the thermal radical polymerization initiator. When a radical polymerizable polymer (a) is included as the radical polymerizable organic compound, the G'80 can be lowered by increasing the content of compounds with a low weight-average molecular weight and / or a low glass transition temperature, and the opposite adjustment can be made to increase the G'80. When a radical polymerizable oligomer (b) and / or radical polymerizable monomer (c) are included as the radical polymerizable organic compound, the G'80 can be lowered by increasing the content of compounds with low viscosity, and the opposite adjustment can be made to increase the G'80. In addition, the G'80 can be increased by increasing the content of the thermal radical polymerization initiator, and the opposite adjustment can be made to decrease the G'80.

[0021] The loss tangent (tanδ80) at 80°C obtained by dynamic viscoelasticity measurement of the dry film is preferably 0.3 to 0.7, and more preferably 0.4 to 0.6. Setting tanδ80 to 0.3 or higher allows the pressure applied to the dry film during the pressing process for sealing the optical semiconductor device to diffuse more uniformly, while setting tanδ80 to 0.7 or lower allows the dry film to adhere more closely to the optical semiconductor device, resulting in superior sealing performance of the optical semiconductor device. Tanδ80 can be measured using the same method as G'80. By adjusting tanδ80 to 0.3-0.7, the diffusivity of the dry film pressure during the pressing process can be increased. tanδ80 can be adjusted by the type, composition, and content of the radical polymerizable organic compound, as well as the content of the thermal radical polymerization initiator. When a radical polymerizable polymer (a) is included as the radical polymerizable organic compound, tanδ80 can be lowered by increasing the content of compounds with a low weight-average molecular weight and / or a low glass transition temperature, and the opposite adjustment can be made to increase tanδ80. When a radical polymerizable oligomer (b) and / or radical polymerizable monomer (c) are included as the radical polymerizable organic compound, tanδ80 can be lowered by increasing the content of compounds with low viscosity, and the opposite adjustment can be made to increase tanδ80. In addition, tanδ80 can be increased by increasing the content of the thermal radical polymerization initiator, and the opposite adjustment can be made to decrease tanδ80.

[0022] The coefficient of dynamic friction on the surface of the dry film is preferably 0.5 or less, more preferably 0.4 or less, and even more preferably 0.35 or less. By setting the coefficient of dynamic friction to 0.5 or less, the flow of the dry film at the contact surface between the optical semiconductor element and the dry film is improved during the pressing process for sealing the optical semiconductor element, resulting in excellent sealing performance of the optical semiconductor element. In addition, air bubbles are less likely to form when bonding the adherend such as the optical semiconductor element to the dry film, resulting in excellent transparency. The lower limit of the coefficient of dynamic friction is 0 or greater, and a value closer to 0 is preferable. The coefficient of dynamic friction can be measured, for example, by the method described in the examples below. The coefficient of dynamic friction can be adjusted by the type, composition, and content of the radical polymerizable organic compound, as well as the content of the thermal radical polymerization initiator. When a radical polymerizable polymer (a) is included as the radical polymerizable organic compound, the coefficient of dynamic friction can be lowered by increasing the content of the component with a high glass transition temperature, and conversely, if the coefficient of dynamic friction is to be increased, the opposite adjustment should be made. When a radical polymerizable oligomer (b) and / or radical polymerizable monomer (c) are included as the radical polymerizable organic compound, the coefficient of dynamic friction can be lowered by increasing the content of the component with low viscosity, and conversely, if the coefficient of dynamic friction is to be increased, the opposite adjustment should be made. In addition, the coefficient of dynamic friction can be lowered by increasing the content of the thermal radical polymerization initiator.

[0023] <Radical polymerizable organic compounds> Radical polymerizable organic compounds are organic compounds containing radical polymerizable groups that can be polymerized and / or crosslinked to increase their molecular weight by applying activation energy in the presence of a thermal radical polymerization initiator. Radical polymerizable organic compounds allow for adjustment of shrinkage force during thermal curing, resulting in desirable sealing properties and low-temperature curing properties. Radical polymerizable groups are, for example, functional groups having unsaturated double bonds, such as (meth)acryloyl groups, N-vinyl groups, vinyl ether groups, allyl groups, and unsaturated carboxylic acid groups. Radical polymerizable organic compounds preferably have at least one radical polymerizable group per molecule, more preferably two or more, and more preferably three or more (polyfunctional) compounds. This facilitates the formation of crosslinked molecular structures, improving low-temperature curing properties.

[0024] Among radically polymerizable organic compounds, compounds having a (meth)acryloyl group are preferred because they are easy to synthesize, obtain, and handle. They are also preferred from the viewpoint of transparency. Examples include epoxy (meth)acrylate, urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and (meth)acrylic acid esters of alcohols.

[0025] Epoxy (meth)acrylate is an acrylate obtained by reacting (meth)acrylic acid with, for example, conventionally known aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, etc. Preferred urethane (meth)acrylates include (meth)acrylates obtained by reacting one or more hydroxyl group-containing polyesters or hydroxyl group-containing polyethers with hydroxyl group-containing (meth)acrylic acid esters and isocyanates, and (meth)acrylates obtained by reacting hydroxyl group-containing (meth)acrylic acid esters and isocyanates.

[0026] Examples of preferred hydroxyl group-containing polyesters include those obtained by the reaction of one or more polyhydric alcohols with one or more polybasic acids. Examples of aliphatic polyhydric alcohols include 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, neopentyl glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, trimethylolpropane, glycerin, pentaerythritol, and dipentaerythritol. Examples of polybasic acids include adipic acid, terephthalic acid, phthalic anhydride, and trimellitic acid.

[0027] Preferred hydroxyl group-containing polyethers include those obtained by adding one or more alkylene oxides to a polyhydric alcohol. Examples of polyhydric alcohols are those similar to those mentioned above. Examples of alkylene oxides include ethylene oxide, propylene oxide, and butylene oxide.

[0028] Preferred hydroxyl group-containing (meth)acrylic acid esters include those obtained by the esterification reaction of a polyhydric alcohol with (meth)acrylic acid. Examples of polyhydric alcohols include those similar to those mentioned above.

[0029] Among such hydroxyl group-containing (meth)acrylic acids, hydroxyl group-containing (meth)acrylic acid esters obtained by the esterification reaction of a dihydric alcohol with (meth)acrylic acid are particularly preferred. A specific example is 2-hydroxyethyl (meth)acrylate.

[0030] As isocyanates, compounds having at least one isocyanate group in the molecule are preferred, and divalent isocyanate compounds such as tolylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate are particularly preferred.

[0031] A preferred polyester (meth)acrylate is one obtained by reacting a hydroxyl group-containing polyester with (meth)acrylic acid. Examples of preferred hydroxyl group-containing polyesters used here include those obtained by the esterification reaction of one or more polyhydric alcohols with one or more monobasic or polybasic acids. Examples of polyhydric alcohols are those similar to those mentioned above. Examples of monobasic acids include formic acid, acetic acid, butyric acid, and benzoic acid. Examples of polybasic acids include adipic acid, terephthalic acid, phthalic anhydride, and trimellitic acid.

[0032] Preferred polyether (meth)acrylates are those obtained by reacting a hydroxyl group-containing polyether with (meth)acrylic acid. Examples of preferred hydroxyl group-containing polyethers used here include those obtained by adding one or more alkylene oxides to a polyhydric alcohol. Examples of polyhydric alcohols are those similar to those mentioned above. Examples of alkylene oxides include ethylene oxide, propylene oxide, and butylene oxide.

[0033] Preferred (meth)acrylic acid esters of alcohols include aromatic or aliphatic alcohols having at least one hydroxyl group in their molecule, and (meth)acrylates obtained by reacting their alkylene oxide adducts with (meth)acrylic acid. Specifically, these include 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, isoamyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isooctyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobonyl (meth)acrylate, benzyl (meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, and Examples include ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ε-caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0034] <Radical polymerizable polymer (a)> A radical polymerizable polymer (a) (hereinafter also referred to as polymer (a)) is an organic compound containing the radical polymerizable group described above, and is a polymer compound having a weight-average molecular weight (Mw) of 10,000 or more and 1,000,000 or less. The upper limit of Mw for polymer (a) is preferably 1,000,000, more preferably 500,000, even more preferably 300,000, and even more preferably 200,000. The lower limit of Mw for polymer (a) is more preferably 10,000, even more preferably 20,000, and even more preferably 30,000. By including such a polymer (a), the film-forming properties of the dry film can be improved. Furthermore, by using a portion of polymer (a) as a dispersant for inorganic fillers and colorants, the uniform dispersion of inorganic fillers and colorants within the dry film can be improved.

[0035] The glass transition temperature of the radical polymerizable polymer (a) is preferably between -50°C and 90°C, more preferably between -15°C and 65°C, and most preferably between 0°C and 50°C. Being within this range allows for the formation of a dry film with good sealing properties. The glass transition temperature was measured using the method described in the examples below.

[0036] It is preferable that the radical polymerizable organic compound contains 95% by mass or more of a radical polymerizable polymer (a) having a glass transition temperature of -50°C to 90°C in 100% by mass. The radical polymerizable polymer (a) preferably contains a radical polymerizable acrylic polymer, more preferably contains 95% by mass or more of a radical polymerizable acrylic polymer, even more preferably contains 97% by mass or more, and may be 100% by mass. It is more preferable that the glass transition temperature of the radical polymerizable acrylic polymer is -50°C to 90°C. The radical polymerizable acrylic polymer referred to here is a polymer that contains structural units derived from acrylic monomers such as meth)acrylic acid, (meth)acrylic acid esters, and acrylonitrile as its main structural units. The main structural units referred to here are those that contain more than 90% by mass of structural units derived from acrylic monomers in 100% by mass of the polymer. The amount of structural units derived from acrylic monomers is preferably 93% by mass or more, more preferably 95% by mass or more, even more preferably 97% by mass or more, and may be 100% by mass.

[0037] The lower limit of the content of radical polymerizable polymer (a) in 100% by mass of the total solids content of the dry film is preferably 10% by mass, more preferably 40% by mass, and even more preferably 60% by mass. The upper limit of the content is preferably 99.9% by mass, more preferably 98% by mass, even more preferably 95% by mass, and even more preferably 90% by mass. By setting the above content, sealing properties and low-temperature curing properties can be suitably adjusted.

[0038] <Radical polymerizable oligomer (b)> The radical polymerizable organic compound may contain a radical polymerizable oligomer (b) in addition to the radical polymerizable polymer (a). A radical polymerizable oligomer (b) (hereinafter also referred to as oligomer (b)) is a polymer having a constituent unit based on 2 to 100 monomers containing radical polymerizable groups, and is liquid at room temperature and atmospheric pressure. It is also a compound with a weight-average molecular weight of less than 10,000. The weight-average molecular weight of oligomer (b) is more preferably 8,000 or less, even more preferably 6,000 or less, and even more preferably 4,500 or less. By setting it within the above range, the fluidity of the dry film can be increased and the sealing performance can be improved. In this disclosure, "room temperature" refers to 25°C, and "normal pressure" refers to 1 atmosphere.

[0039] The oligomer (b) may be present in an amount of 0.1 to 70% by mass, 1 to 50% by mass, 10 to 50% by mass, or 30 to 50% by mass, based on 100% by mass of the total solids content of the dry film. By using the above content ratios, sealing properties, low-temperature curing properties, and handling properties can be suitably adjusted.

[0040] <Radical polymerizable monomer (c)> The radical polymerizable organic compound may further contain a radical polymerizable monomer (c) (hereinafter also referred to as monomer (c)) in addition to the radical polymerizable polymer (a). A radical polymerizable monomer (c) refers to a compound having a radical polymerizable group, which is the smallest structural unit for constituting oligomers or polymers, and is liquid at room temperature and pressure. The monomer may be monofunctional or polyfunctional. In particular, (meth)acrylate compounds can be used because they are easy to handle. From the viewpoint of sealing properties, the compound may contain 2- to 6-functional (meth)acrylate monomers, or 2- to 3-functional (meth)acrylate monomers.

[0041] The monomer (c) may be present in an amount of 0.01 to 70% by mass, 0.1 to 50% by mass, 1 to 30% by mass, or 1 to 10% by mass, based on 100% by mass of the total solids content of the dry film. By using the above content ratios, the sealing properties and low-temperature curing properties can be suitably adjusted.

[0042] If the dry film contains an oligomer (b) or monomer (c), it is preferable that it contains a binder resin, as described later, for the purpose of suppressing tack, from the viewpoint of handling the dry film. The binder resin preferably contains 30 parts by mass or more, and more preferably 50 parts by mass or more, per 100 parts by mass of oligomer (b) and monomer (c). Within this range, a dry film can be produced that achieves both sealing properties and low-temperature curing properties, while also being easy to handle.

[0043] <Thermal radical polymerization initiator> The 10-hour half-life temperature of the thermal radical polymerization initiator is between 60°C and 170°C. Setting the temperature above 60°C maintains the storage stability of the dry film and ensures good sealing performance even after long-term storage. It also prevents rapid polymerization (curing) due to heat pressing during sealing, resulting in good sealing performance. From these viewpoints, the lower limit of the 10-hour half-life temperature is more preferably 80°C, and even more preferably 100°C. Setting the temperature below 170°C lowers the thermosetting temperature of the dry film and shortens the curing time, thereby improving low-temperature curing performance. From this viewpoint, the upper limit of the 10-hour half-life temperature is more preferably 160°C, and even more preferably 150°C.

[0044] When the substrate contains precision elements, a reduction in the manufacturing process temperature is sometimes required. Lowering the aging temperature during the sealing process and curing of the dry film can significantly increase the versatility of the dry film. It also greatly expands the range of selectable materials such as micro-LEDs and substrates. Furthermore, it is desirable from the standpoint of energy saving. As a result of diligent research by the inventors, it has been discovered that by using a peroxide-based thermal radical polymerization initiator with a 10-hour half-life temperature of 60 to 120°C, a dry film with excellent optical properties, sealing properties, low-temperature curing properties, post-curing appearance, storage stability, and handling, as well as superior appearance, can be obtained. From the viewpoint of appearance, a 10-hour half-life temperature of 70 to 115°C is more preferable, 75 to 110°C is even more preferable, and 80 to 110°C is even more preferable.

[0045] The 10-hour half-life temperature is the temperature at which the concentration of a thermal radical polymerization initiator decreases by half after 10 hours due to thermal decomposition. Specifically, a solution of the thermal radical polymerization initiator is prepared using a solvent inert to the radicals of the thermal radical polymerization initiator, and sealed in a glass tube purged with nitrogen. This is then immersed in a constant temperature chamber set to a predetermined temperature for 10 hours to allow thermal decomposition, and the amount of remaining thermal radical polymerization initiator is measured. By performing this series of operations at several temperatures and plotting the results, the 10-hour half-life temperature can be determined from the resulting straight line.

[0046] Thermal radical polymerization initiators can include azo thermal polymerization initiators and organic peroxide polymerization initiators. From the viewpoint of storage stability, azo thermal polymerization initiators are preferably used. From the viewpoint of suppressing foaming during curing and improving the appearance after curing, organic peroxide polymerization initiators are preferably used. Thermal radical polymerization initiators adjust the shrinkage force during thermal curing, resulting in desirable sealing properties and low-temperature curing properties.

[0047] Examples of organic peroxide polymerization initiators with a 10-hour half-life temperature of 60°C to 170°C include dialkyl peroxides such as di-t-amyl peroxide (123°C), di-t-butyl peroxide (129°C), di-t-hexyl peroxide (116°C), dicumyl peroxide (116°C), t-butylcumyl peroxide (120°C), α,α'-bis(t-butylperoxy-m-isopropyl)benzene (119°C), 2,5-dimethyl-2,5-bis(t-butylperoxy)hexine-3 (131°C), and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (120°C); t-Amyl peroxyacetate (100°C), t-Butyl peroxyacetate (102°C), t-Amyl peroxybenzoate (100°C), t-Butyl peroxybenzoate (104°C), t-Hexyl peroxybenzoate (99°C), t-Amyl peroxy-2-ethylhexanoate (75°C), t-Butyl peroxy-2-ethylhexanoate (72°C), t-Hexyl peroxy-2-ethylhexanoate (70°C), 1,1,3,3-Tetramethylbutyl peroxy-2-ethylhexanoate (65°C), t-Butyl Peroxyesters such as peroxy-3,5,5-trimethylhexanoate (97°C), t-butyl peroxyisobutyrate (75°C), t-amyl peroxyisononanoate (96°C), t-butyl peroxyisononanoate (102°C), t-butyl peroxylaurate (98°C), n-butyl 4,4-di-(t-butylperoxy)valerate (105°C), 2,5-dimethyl-2,5-di(benzoylperoxy)hexane (100°C), and 2,5-dimethyl-2,5-di-2-ethylhexanoylperoxyhexane (66°C); Peroxyketals such as 2,2-bis(t-butylperoxy)butane (103°C), 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane (95°C), 1,1-bis(t-amylperoxy)cyclohexane (93°C), 1,1-bis(t-butylperoxy)cyclohexane (97°C), 1,1-bis(t-hexylperoxy)cyclohexane (87°C), and 4,4-bis(t-butylperoxy)butyl pentanoate; Hydroperoxides such as t-amyl hydroperoxide (165°C), cumene hydroperoxide (158°C), p-menthane hydroperoxide (128°C), diisopropylbenzene hydroperoxide (145°C), and 1,1,3,3-tetramethylbutyl hydroperoxide (153°C); Diacyl peroxides such as dibenzoyl peroxide (73°C), diisononanoyl peroxide (61°C), dilauroyl peroxide (64°C), and disuccinate peroxide (66°C); Examples of peroxy carbonates include, but are not limited to, t-butyl peroxyisopropyl carbonate (99°C), t-amyl peroxyisopropyl carbonate (96°C), t-hexyl peroxyisopropyl carbonate (95°C), t-butyl peroxy-2-ethylhexyl carbonate (99°C), and t-amyl peroxy-2-ethylhexyl carbonate (99°C). From the viewpoint of storage stability, dialkyl peroxides are preferred, and di-t-butyl peroxide and t-butyl peroxybenzoate are more preferred.

[0048] Examples of azo thermal polymerization initiators with a 10-hour half-life temperature of 60°C to 170°C include 2,2'-azobisisobutyronitrile (65°C), 2,2'-azobis(2-methylbutyronitrile) (68°C), and other 2,2'-azobisbutyronitriles; 1,1'-azobis-1-alkanenitriles such as 1,1'-azobis(cyclohexane-1-carbonitride) (88°C); 2,2'-azobispropionamides such as 2,2'-azobis(N-butyl-2-methylpropionamide) (110°C); Other examples include dimethyl-1,1'-azobis(1-cyclohexanecarboxylate) (73°C), dimethyl-2,2'-azobis(2-methylpropionate) (66°C), 2,2'-azobis(2,4,4-trimethylpentane) (110°C), and 2,2'-azobis[2-(2-imidazolin-2-yl)propane] (61°C). Azo compounds having carboxyl groups or hydroxyl groups include, but are not limited to, 4,4'-azibis(4-cyanopentanoic acid) and 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide). From the viewpoint of storage stability, 2,2'-azobispropionamides are preferred, and 2,2'-azobis(N-butyl-2-methylpropionamide) is more preferred.

[0049] The thermal radical polymerization initiator is preferably contained in an amount of 0.01 to 20% by mass, more preferably 0.1 to 18% by mass, and even more preferably 0.8 to 16% by mass, based on 100% by mass of the total solids content of the dry film. 1 to 13% by mass is particularly preferred. A concentration of 0.01 to 20% by mass provides excellent transparency of the cured dry film in transparent applications. Furthermore, a concentration of 0.01% by mass or more provides excellent low-temperature curing properties and handling, while a concentration of 20% by mass or less provides excellent storage stability.

[0050] Furthermore, from the viewpoint of storage stability, it is preferable not to use thermal radical polymerization initiators in combination with photoradical polymerization initiators.

[0051] <Other ingredients> The dry films of this disclosure may contain other components, to the extent that they do not impair the purpose of this disclosure. For example, colorants, inorganic fillers, dispersants, binder resins, silane coupling agents, etc., may be added.

[0052] <Coloring agent> For the purpose of forming a reflective layer, a coloring agent (P) such as titanium dioxide, zinc oxide, or lithopone can be used. From the viewpoint of whiteness, a white pigment is preferred, and among these, titanium dioxide is preferred from the viewpoint of dispersibility. By using a white pigment to make the dry film white and sealing the spaces between multiple microLEDs or around multiple microLEDs, the sealing layer functions as a reflective layer, and the brightness of the microLEDs can be further increased.

[0053] Known titanium dioxide such as rutile-type titanium dioxide and anatase-type titanium dioxide can be used as the titanium dioxide used in this disclosure. From the viewpoint of resin degradation due to light, rutile-type titanium dioxide is preferred. Specific examples of rutile-type titanium dioxide include "Typeque R-820, R-830, R-930, R-550, R-630, R-680, R-670, R-680, R-670, R-780, R-850, CR-50, CR-57, CR-80, CR-90, 90-2, CR-93, CR-95, CR-97, CR-63, CR-58, UT771" from Ishihara Sangyo Co., Ltd., "Typeque R-101, R-103, R-104, R-105, R-108, R-900, R-902+, R-960, R-706" from DuPont, and "TITONE" from Sakai Chemical Industry Co., Ltd. Examples include "R-25, R-21, R-32, R-7E, R-5N, R-62N, R-42, R-45M, GTR-100, D-918," etc.

[0054] The arithmetic mean particle size of rutile-type titanium dioxide is preferably 0.1 to 1.5 μm, and more preferably 0.15 to 1.1 μm. Setting the arithmetic mean particle size to 0.1 μm or more makes it easier to prevent aggregation and sedimentation of titanium dioxide in coating solutions for dry films. Furthermore, setting the arithmetic mean particle size to 1.5 μm or less improves whiteness and exhibits high reflectivity. When the particle shape of the colorant (P) has an average aspect ratio (long axis length / short axis length) of 1.5 or more, the arithmetic mean particle size is determined by averaging the long axis lengths. The arithmetic mean particle size of the colorant (P) can be determined from the average value of about 20 primary particles that can be observed from an image magnified to about 50,000 to 1,000,000 times using a transmission electron microscope (TEM).

[0055] The amount of white pigment blended is preferably 0.1 to 35% by mass of the colorant (P) per 100% by mass of the total solids content of the dry film. The lower limit of the blending amount is more preferably 0.5% by mass, even more preferably 1% by mass, and even more preferably 5% by mass. The upper limit of the blending amount is more preferably 30% by mass, even more preferably 28% by mass, and particularly preferably 20% by mass. By having a content of 0.1 to 35% by mass, a dry film with good reflectivity, sealing properties, and handling properties can be obtained.

[0056] When the purpose is to form a light-shielding layer, it is preferable to use a black coloring agent (P) (pigment, dye, etc.). Specifically, examples include carbon black, graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite (non-magnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, anthraquinone-based coloring agents, zirconium nitride, etc. One type of black coloring agent may be used, or two or more types may be used. In addition, a coloring agent that functions as a black coloring agent may be used by combining coloring agents that exhibit colors other than black.

[0057] Among the colorants (Q), carbon black is particularly preferred in terms of its dispersibility in radically polymerizable organic compounds and its light-shielding properties. The carbon black used can be any carbon black commonly used as a black colorant. As the carbon black, one or more known types of carbon black, such as channel black, furnace black, thermal black, lamp black, or acetylene black, can be used. Resin-coated carbon black may also be used. Furthermore, carbon nanofibers or carbon nanotubes may be used. When incorporating carbon black into a dry film, either carbon black powder or a carbon black dispersion may be added. The average particle size of carbon black is preferably between 10 nm and 500 nm, more preferably between 10 nm and 300 nm, and even more preferably between 10 nm and 100 nm, from the viewpoint of light shielding properties. The average particle size is the arithmetic mean primary particle size determined by observation with an electron microscope. From the perspective of dispersibility, carbon black has a specific surface area of ​​50-400 m² as measured by the BET method. 2 Preferably, the product has a volatile content of 0.1 to 10% by weight, a pH of 2 to 10, a pH of 3 to 8 is more preferable, and a pH of 3 to 6 is even more preferable.

[0058] The amount of black pigment can be 0.1% by mass or more of the total solid content of the dry film by 100% by mass. The lower limit of the amount of colorant is more preferably 0.5% by mass, even more preferably 1% by mass, and still more preferably 1% by mass. The upper limit of the amount of black pigment is, for example, 80% by mass, 40% by mass, etc. From the viewpoint of obtaining a dry film with good light-shielding properties, sealing properties, and handling properties, the upper limit is preferably 35% by mass, more preferably 30% by mass, even more preferably 28% by mass, and still more preferably 20% by mass.

[0059] <Inorganic filler> The dry film may contain inorganic fillers other than those mentioned above (hereinafter simply referred to as inorganic fillers). Examples of such inorganic fillers include inorganic compounds such as silica, alumina, titanium oxide, antimony trioxide, magnesium oxide, tin oxide, zirconium oxide, magnesium hydroxide, barium sulfate, calcium carbonate, talc, kaolinite, mica, sericite, montmorrolinite, bentonite, magnesium carbonate base, boron nitride, aluminum nitride, and titanium nitride. When imparting high refractive index to the dry film, it is preferable that the total light transmittance in the visible light band (380-780 nm) of the dry film be 70% or more, and the refractive index be 1.47-1.56. A total light transmittance of 80% or more is more preferable, 85% or more is even more preferable, 90% or more is even more preferable, and 92% or more is particularly preferable. The lower limit of the refractive index is more preferable to 1.49, and 1.51 is even more preferable. The upper limit of the refractive index is more preferable to 1.54, and 1.53 is even more preferable. Inorganic fillers such as alumina, titanium oxide, and zirconium oxide may be added to adjust the refractive index. Total light transmittance is the ratio of the total amount of transmitted light that passes through the cured layer to the total amount of incident light that enters the cured layer obtained by heating the dry film at 130°C for 120 minutes.

[0060] Inorganic fillers, from the perspective of dispersibility, have a specific surface area of ​​5-400 m² as measured by the BET method. 2 It is preferable that the value be / g, and 10 to 150m 2 It is more preferable that the amount be / g, and 20-90m2 It is even more preferable that it be / g. The average primary particle diameter (hereinafter referred to as particle diameter) of the inorganic filler is preferably 1 to 1200 nm. A particle diameter of 1 nm or more makes it easier to maintain the viscosity of the resin composition at a level suitable for coating. Furthermore, a particle diameter of 1200 nm or less improves the coating film resistance. A particle diameter of 5 to 1000 nm is more preferable, 10 to 700 nm is even more preferable, and 50 to 300 nm is particularly preferable. The particle diameter of the inorganic filler can be determined from the average value of about 20 primary particles observed from an image magnified to approximately 50,000 to 1,000,000 times using a transmission electron microscope (TEM). If the particle shape of the inorganic filler has an average aspect ratio (long axis length / short axis length) of 1.5 or more, the particle diameter is determined by averaging the long axis lengths.

[0061] The inorganic filler content (total content if two or more types are included) is preferably 0.01 to 40% by mass, more preferably 0.1 to 30% by mass, and even more preferably 0.5 to 20% by mass, based on the total amount of solids in the dry film, from the viewpoint of embedding properties. Including 0.01 to 40% by mass of inorganic filler makes it easier to increase the fluidity of the dry film during the pressing process, thereby improving embedding properties.

[0062] From the viewpoint of dispersibility, it is preferable that the inorganic filler is surface-modified with a surface modifier. Examples of surface modifiers include organic acids, silane coupling agents, surfactants, titanium coupling agents, and metal impurities, and it is preferable that the inorganic filler contains an organic acid.

[0063] From the viewpoint of adjusting the film-forming properties and reflectivity of the sealing layer, it is preferable to disperse the colorant (Q) and inorganic filler in polymer (a) and use them as a dispersion. As for the dispersion treatment, any commonly used disperser can be used for mechanical crushing, but examples include ball mills, roll mills, sand mills, bead mills and nanomizers. Among these, bead mills are preferably used. Examples of such bead mills include Supermill, Sand Grinder, Agitator Mill, Glenmill, Dynomill, Pearlmill and Cobolmill (all are trade names).

[0064] In this disclosure, from the viewpoint of storage stability of the dispersion, it is preferable to use a dispersant in the dispersion treatment of the colorant (Q) and inorganic filler. In this disclosure, the dispersant has the function of imparting repulsive force between particles so that the particles separated after the aforementioned dispersion treatment do not aggregate again. Conventional known compounds can be used as dispersants, including, for example, cationic, anionic, or nonionic surfactants, cationic, anionic, or nonionic polymeric dispersants, and pigment derivative type dispersants. From the viewpoint of storage stability of the dispersion, pigment derivative type dispersants are preferred.

[0065] Pigment derivative-type dispersants are compounds having acidic groups, basic groups, neutral groups, etc., in their organic pigment residues. Examples include compounds having acidic substituents such as sulfo groups, carboxyl groups, or phosphate groups, as well as their amine salts, compounds having basic substituents such as sulfonamide groups, amide groups, or tertiary amino groups at the terminal, and compounds having neutral substituents such as phenyl groups or phthalimidoalkyl groups. Examples of organic pigments include phthalocyanine pigments, diketopyrrolopyrrole pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, perinone pigments, perylene pigments, thiaidine indigo pigments, triazine pigments, benzimidazolone pigments, indole pigments such as benzoisoindole, isoindoline pigments, isoindolinone pigments, quinophthalone pigments, naphthol pigments, surene pigments, metal complex pigments, and azo pigments such as azo, disazo, and polyazo. By using these pigment dispersants, it is possible to prevent the aggregation of colorants (Q) and inorganic fillers contained in the dry film over time, thereby maintaining good reflectivity.

[0066] When the dry film contains a white coloring agent, the dispersant content (total content if two or more types are included) is preferably 0.01 to 35% by mass, and more preferably 0.1 to 20% by mass, based on the total amount of the dry film (100% by mass). Including 0.01% by mass or more of the dispersant results in good light reflectivity, and an amount of 35% by mass or less results in a suitable viscosity range for the white resin composition for forming the sealing layer, thus improving coating suitability. When the dry film contains a black coloring agent, the pigment dispersant content (total content if two or more types are included) is preferably 0.01 to 30% by mass, and more preferably 0.1 to 20% by mass, based on the total amount of the dry film (100% by mass). Including 0.01% by mass or more of the pigment dispersant results in good light shielding properties, and an amount of 30% by mass or less results in a suitable viscosity range for the black resin composition for forming the sealing layer, leading to good coating suitability. When the dry film contains inorganic fillers, the dispersant content is preferably 0.01 to 45% by mass, more preferably 0.1 to 35% by mass, and more preferably 1 to 30% by mass, based on the total amount of solids in the dry film. Including 0.01% by mass or more of dispersant results in good brightness of the optical semiconductor device, and an amount of 45% by mass or less results in a suitable viscosity range for the dispersion, leading to good coating suitability.

[0067] <Binder resin> The binder resin does not contain the aforementioned radical polymerizable groups and is an organic polymer compound different from radical polymerizable organic compounds. Furthermore, the binder resin is an organic polymer compound having a glass transition temperature of -50°C to 90°C and a weight-average molecular weight of 10,000 to 1,000,000. More preferably, the binder resin has a glass transition temperature of -15°C to 50°C, even more preferably 0°C to 25°C, a weight-average molecular weight of 25,000 to 200,000, and even more preferably 30,000 to 100,000.

[0068] The binder resin can be a known and conventional thermosetting resin or thermoplastic resin. Specifically, examples include acrylic resins, maleic acid resins, polybutadiene resins, polyester resins, polyurethane resins, epoxy resins, oxetane resins, phenoxy resins, polyimide resins, polyamide resins, phenolic resins, alkyd resins, amino resins, polylactic acid resins, oxazoline resins, benzoxazine resins, silicone resins, fluororesins, butyral resins, styrene-maleic acid copolymers, chlorinated polyethylene, chlorinated polypropylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, polyvinyl acetate, polyester resins, vinyl resins, alkyd resins, polystyrene resins, polyamide resins, rubber resins, cyclocarbonate resins, celluloses, polyethylene (HDPE, LDPE), polybutadiene, carbodiimide resins, cyclocarbonate compounds, episulfide resins, and polyimide resins. Acrylic resins, polyurethane resins, and epoxy resins are particularly preferred, with acrylic resins being more preferred. By including a binder resin, the stickiness of the dry film can be adjusted, improving its handling properties.

[0069] Furthermore, when a thermosetting resin is included as the binder resin, it is preferable to include a curing agent to promote the formation of a crosslinked structure. The curing agent has multiple functional groups that can react with the functional groups of the thermosetting resin. Examples of known curing agents include epoxy crosslinking agents, acid anhydride group-containing compounds, imidazole compounds, isocyanate compounds, blocked isocyanate compounds, aziridine compounds, and amine compounds. By including a curing agent, the degree of crosslinking of the dry film can be adjusted and the low-temperature curing properties can be improved.

[0070] <Silane coupling agent> Silane coupling agents are compounds in which hydrolyzable groups such as methoxy groups and ethoxy groups, and functional groups such as epoxy groups, are bonded to Si atoms via alkylene groups. Silane coupling agents act on both the substrate on which the light-emitting element is mounted and the polymer (a), and have the function of improving the adhesion of the sealing layer.

[0071] Silane coupling agents include alkoxysilane compounds having a (meth)acryloxy group, such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyltripropoxysilane, 3-(meth)acryloxypropyltributoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and methacryloxyoctyltrimethoxysilane; Alkoxysilane compounds having a vinyl group, such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, and vinylmethyldiethoxysilane; Alkoxysilane compounds having an amino group, such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane; Alkoxysilane compounds having a mercapto group, such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropylmethyldiethoxysilane; Alkoxysilane compounds having one epoxy group, such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; Tetraalkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane; Examples include 3-chloropropyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, styryltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 3-isocyanatetopropyltrimethoxysilane, 3-isocyanatetopropyltriethoxysilane, hexamethyldisilazane, and silicone resins having alkoxysilyl groups in the molecule. Alkoxysilane compounds are preferred from the viewpoint of adhesion, and 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and methacryloxyoctyltrimethoxysilane are more preferred.

[0072] The silane coupling agent content is preferably 0.01 to 15% by mass, more preferably 0.05 to 10% by mass, and even more preferably 0.1 to 5% by mass, based on the total solid content of the dry film. By setting it to 0.01 to 15% by mass, the adhesion can be suitably adjusted.

[0073] <Crosslinkable component> Dry films can contain crosslinking components such as crosslinking agents, curing accelerators, and curing retarders. The inclusion of crosslinking components allows for adjustment of the mechanical strength and elastic modulus of the cured dry film. Furthermore, it allows for adjustment of the curing speed during hot pressing and heat aging processes.

[0074] The crosslinking agent preferably enhances the cohesive force of the dry film and improves adhesion by crosslinking with the reactive functional groups of polymer (a). The crosslinking agent is preferably one having multiple functional groups that can react with the functional groups of polymer (a). Suitable examples of crosslinking agents include known compounds of epoxy compounds, aziridine compounds, imidazole compounds, isocyanate compounds, acid anhydride group-containing compounds, and amine compounds. From the viewpoint of adjusting the adhesion of the dry film to the adherend, epoxy compounds, aziridine compounds, imidazole compounds, and isocyanate compounds are preferred, with aziridine compounds being more preferred. The dry film is more preferably a combination of a radically polymerizable acrylic polymer and a crosslinking agent capable of crosslinking with the reactive functional groups of this radically polymerizable acrylic polymer.

[0075] The epoxy compound is a compound having two or more epoxy groups in one molecule, other than polymer (a) which has a structural unit based on the epoxy group-containing monomer described above. Examples of epoxy compounds include glycyl ether type epoxy compounds, glycylamine type epoxy compounds, glycidyl ester type epoxy compounds, cyclic aliphatic (alicyclic) epoxy compounds, bisphenol type epoxy compounds, and hydrogenated bisphenol type epoxy compounds.

[0076] Examples of aziridine compounds include trimethylolpropane tris[3-(aziridin-1-yl)propionate], tetramethylolmethane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridincarboxyamide), N,N'-hexamethylene-1,6-bis(1-aziridincarboxyamide), tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, and 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane.

[0077] The isocyanate compound is an isocyanate having two or more isocyanate groups, and is a compound other than polymer (a) having a structural unit based on the isocyanate group-containing monomer described above. The isocyanate compound is preferably an isocyanate monomer such as aromatic polyisocyanates, aliphatic polyisocyanates, aromatic aliphatic polyisocyanates, or alicyclic polyisocyanates, as well as their burette, nurate, and adduct forms. From the viewpoint of forming a sufficient crosslinking structure, trifunctional isocyanate compounds are preferred. More preferably, the isocyanate compounds are adducts and nurates, which are reaction products of an isocyanate monomer and a trifunctional low-molecular-weight active hydrogen-containing compound. The isocyanate compounds are preferably trimethylolpropane adducts of hexamethylene diisocyanate, nurates of hexamethylene diisocyanate, trimethylolpropane adducts of tolylene diisocyanate, nurates of tolylene diisocyanate, trimethylolpropane adducts of isophorone diisocyanate, and nurates of isophorone diisocyanate, and more preferably trimethylolpropane adducts of hexamethylene diisocyanate, trimethylolpropane adducts of tolylene diisocyanate, and trimethylolpropane adducts of isophorone diisocyanate.

[0078] The crosslinking agent content is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, and even more preferably 0.5 to 5% by mass, based on the total amount of solids in the dry film. Adhesion can be suitably adjusted by setting the content to 0.01 to 20% by mass. When the crosslinking agent is an epoxy compound, the epoxy compound content is preferably 0.01 to 10% by mass, more preferably 0.03 to 10% by mass, even more preferably 0.05 to 7% by mass, and particularly preferably 0.1 to 5% by mass, based on the total amount of solids in the dry film (100% by mass). Adhesion can be suitably adjusted by setting the content to 0.01% by mass or more. Insulation can be suitably adjusted by setting the content to 10% by mass or less.

[0079] <Method for forming dry film> The method for forming a dry film is not particularly limited, but a preferred example is a method in which a liquid dry film precursor, obtained by adding an arbitrary solvent to the components constituting the dry film, is coated, and the solvent is dried to form a dry film. The purpose of adding the solvent is to adjust the viscosity level to one suitable for coating. For coating, known coating machines and techniques such as comma coaters, die coaters, roll coaters, lip coaters, reverse coaters, gravure coaters, bar coaters, curtain coaters, dip coating, spin coating, silkscreen, and casting can be used. The solvent contained in the dry film precursor can be removed by a drying process after coating. In a preferred embodiment, a dry film precursor can be applied to a support such as a release liner or substrate, and then the applied film can be heated and dried using a hot air oven, infrared heater, or the like to form a dry film on one surface of the support. Furthermore, in order to increase the crosslinking density of the dry film, an aging treatment such as standing under specific temperature conditions or irradiation with UV light may be performed.

[0080] <Removable Liner> The release liner supports the dry film and is a film to which a dry film precursor is coated when the dry film is formed. Examples of release liners include polyester films such as polyethylene terephthalate and polyethylene naphthalate, films made of thermoplastic resins such as polyimide films, polyamide-imide films, polyethylene films, polytetrafluoroethylene films, polypropylene films, and polystyrene films, as well as paper. Among these, polyester films are preferable from the viewpoint of heat resistance, mechanical strength, and handling. The thickness of the release liner is not particularly limited, but is generally selected appropriately within the range of 10 to 150 μm depending on the application. The surface of the release liner on which the dry film precursor is applied may be treated with a release agent.

[0081] <Protective Film> The protective film is preferably provided on the surface of the dry film opposite to the release liner for the purpose of preventing dust and the like from adhering to the surface of the dry film and improving handling properties. As the protective film, for example, polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyimide films, polyamideimide films, polyethylene films, polytetrafluoroethylene films, polypropylene films, polystyrene films, etc., which are made of thermoplastic resins, and papers, etc. can be used. Among these, polyester films can be preferably used from the viewpoints of heat resistance, mechanical strength, handling properties, etc. The thickness of the protective film is not particularly limited, but is generally appropriately selected according to the application within the range of 10 to 150 μm. The surface of the protective film that contacts the dry film may be subjected to an antistatic treatment, an adhesion treatment, a release treatment, or an uneven treatment. Also, in the release force (Tl) between the release liner and the dry film and the release force (Th) between the protective film and the dry film, it is preferable to satisfy the relationship of Tl < Th.

[0082] <Electronic Device> The cured product of the dry film is preferably mounted on electronic devices such as liquid crystal displays, touch panels, as well as notebook PCs, mobile phones, smartphones, tablet terminals, etc.

Examples

[0083] Hereinafter, the present disclosure will be specifically described by showing examples and comparative examples of the present disclosure, but it is needless to say that the present disclosure is not limited to these examples. In the following, "parts" and "%" are all based on mass unless otherwise specified.

[0084] The numerical values obtained in this example are the values obtained by the following method. <Weight Average Molecular Weight (Mw)> For the measurement of Mw, "LC-GPC System", a GPC manufactured by Shimadzu Corporation, was used, and Mw was determined by converting using polystyrene with a known molecular weight as a standard substance. Equipment name: Shimadzu Corporation, LC-GPC system "Prominence" Columns: Four Tosoh GMHXL columns and one Tosoh HXL-H column were connected together. Mobile phase solvent: tetrahydrofuran Flow rate: 1.0mL / min Column temperature: 40℃

[0085] <Glass transition temperature> The glass transition temperature of the radical polymer (a) was determined using JIS-K7121 (DSC method: heating rate 10°C / min). A differential scanning calorimetry system (DSC2500: TA Instruments Inc.) was used as the measurement device.

[0086] The materials used in the examples and comparative examples are shown below. <Radical polymerizable organic compounds> [Radical polymerizable acrylic polymer (a)-1] To 100 parts by mass of Acrydic A-814 (DIC Corporation, acrylic polyol resin, hydroxyl value 17.5 mg KOH / g), 15 parts by mass of solvent (ethyl acetate) were added and stirred. Then, 15 parts by mass of Karenz AOI (2-acryloyloxyethyl isocyanate, Resonaq Corporation) was added and the mixture was stirred at 60°C for 24 hours to obtain radical polymerizable acrylic polymer (a)-1. The glass transition temperature was 85°C. [Radical polymerizable acrylic polymer (a)-2] To 100 parts by mass of Acrydic A-801P (manufactured by DIC, an acrylic polyol resin with a hydroxyl value of 50 mg KOH / g), 15 parts by mass of solvent (ethyl acetate) were added and stirred. Then, 15 parts by mass of Karenz AOI (2-acryloyloxyethyl isocyanate, manufactured by Resonaq) were added, and the mixture was stirred at 60°C for 24 hours to obtain radical polymerizable acrylic polymer (a)-2. The glass transition temperature was 50°C. [Radical polymerizable acrylic polymer (a)-3] To 100 parts by mass of Acrydic 44-127 (DIC Corporation, acrylic polyol resin, hydroxyl value 70 mg KOH / g), 15 parts by mass of solvent (ethyl acetate) were added and stirred. Then, 15 parts by mass of Karenz AOI (2-acryloyloxyethyl isocyanate, Resonaq Corporation) was added, and the mixture was stirred at 60°C for 24 hours to obtain radical polymerizable acrylic polymer (a)-3. The glass transition temperature was 35°C. [Radical polymerizable acrylic polymer (a)-4] To 100 parts by mass of Acrydic A-811 (DIC Corporation, acrylic polyol resin, hydroxyl value 34 mg KOH / g), 15 parts by mass of solvent (ethyl acetate) were added and stirred. Then, 15 parts by mass of Karenz AOI (2-acryloyloxyethyl isocyanate, Resonaq Corporation) was added, and the mixture was stirred at 60°C for 24 hours to obtain radical polymerizable acrylic polymer (a)-4. The glass transition temperature was 20°C. [Radical polymerizable acrylic polymer (a)-5] To 100 parts by mass of Acrydic 49-394-IM (DIC Corporation, acrylic polyol resin, hydroxyl value 25 mg KOH / g), 15 parts by mass of solvent (ethyl acetate) were added and stirred. Then, 15 parts by mass of Karenz AOI (2-acryloyloxyethyl isocyanate, Resonaq Corporation) was added, and the mixture was stirred at 60°C for 24 hours to obtain radical polymerizable acrylic polymer (a)-5. The glass transition temperature was 15°C. [Radical polymerizable acrylic polymer (a)-6] To 100 parts by mass of Acrydic A-817 (DIC Corporation, acrylic polyol resin, styrene-acrylic copolymer, hydroxyl value 60 mg KOH / g), 15 parts by mass of solvent (ethyl acetate) were added and stirred. Then, 15 parts by mass of Karenz AOI (2-acryloyloxyethyl isocyanate, Resonaq Corporation) was added and stirred at 60°C for 24 hours to obtain radical polymerizable acrylic polymer (a)-6. The glass transition temperature was 95°C.

[0087] <Thermal radical polymerization initiator> The thermal radical polymerization initiator used was one of the thermal polymerization initiators listed in Table 1. [Table 1]

[0088] <Silane coupling agent> (C-1) KBM-502 (manufactured by Shin-Etsu Silicone Co., Ltd.) <Inorganic filler> (P-1)PCS-60 (manufactured by Nippon Denko) <Coloring agent (Q)> (Q-1) Typeque CR-97 (manufactured by Ishihara Sangyo Co., Ltd.) (Q-2) Mitsubishi Carbon MA100 (manufactured by Mitsubishi Chemical Corporation) <Dispersant> (D-1) DISPEARBYK142 (manufactured by BYK) (D-2) Solsperse 5000 (manufactured by Lubrizol)

[0089] [Example 101] A radically polymerizable acrylic polymer (a)-1 was used as the radically polymerizable organic compound. To 100 parts by mass of the solid content of (a)-1, 5 parts by mass of Luperox 230 (manufactured by Arkema Yoshitomi Co., Ltd.) as a thermal radical polymerization initiator, 1 part by mass of silane coupling agent C-1, and 38 parts by mass of diluent solvent (methyl ethyl ketone, toluene mixed solvent) were sequentially added while stirring with a disperser, and the mixture was stirred until it was sufficiently homogeneous to obtain a dry film precursor (1). A dry film precursor (1) was applied to the release layer of a 75 μm thick release liner (SP-PET-O3, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) so that the thickness after drying would be 25 μm, and a dry film was formed by heating and drying in a hot air oven at 80°C. Next, the dry film was covered with a protective film, SP-PET-O1 (manufactured by Mitsui Chemicals Tohcello Co., Ltd.), to obtain a dry film with a release liner and protective film.

[0090] [Examples 102-116, Comparative Example 101] As shown in Table 2A, Examples 102 to 116 and Comparative Example 101 were obtained in the same manner as Example 101, except that the type of radical polymerization organic compound and the type and amount of radical polymerization initiator were changed. The composition ratios in Table 2A are listed as the ratio of active ingredients excluding the solvent. Note that the lower row of the composition in Table 2A is based on 100% by mass of dry film solids. The same applies hereafter.

[0091] [Example 201] A radically polymerizable acrylic polymer (a)-1 was used as the radically polymerizable organic compound. 100 parts by mass of the solid content of (a)-1 was mixed in a 0.45 L container with 20 parts by mass of PCS-60 (manufactured by Shin-Nippon Denko Co., Ltd.), which is zirconium oxide, as the inorganic filler P-1; 5 parts by mass of DISPEARBYK142 as the dispersant D-1; and 200 parts by mass of methyl isobutyl ketone as the solvent. The mixture was then pre-dispersed using a disperser. Subsequently, 1300 parts by mass of 1.0 mm diameter zirconia beads were added, and the mixture was fully dispersed for 1 hour using a shaker (Scandex SK450: manufactured by Fast & Fluid Management). The zirconia beads were then removed to obtain a high refractive index dispersion. To the obtained high refractive index dispersion, 5 parts by mass of Luperox 230 (manufactured by Arkema Yoshitomi Co., Ltd.) as a thermal radical polymerization initiator, 1 part by mass of silane coupling agent C-1, and 38 parts by mass of diluent solvent (methyl ethyl ketone and toluene mixed solvent) were sequentially added while stirring with a disperser. The mixture was then stirred until it was sufficiently homogeneous to obtain a dry film precursor. Subsequently, a dry film with a release liner and protective film was obtained in the same manner as in Example 101.

[0092] [Examples 202-218, Comparative Example 201] As shown in Table 3A, Examples 202 to 218 and Comparative Example 201 were obtained in the same manner as Example 201, except that the type of radical polymerization organic compound and the type and amount of radical polymerization initiator were changed. The composition ratios in Table 3A are listed as the ratio of active ingredients excluding the solvent.

[0093] [Examples 301-318, Comparison 301] As shown in Table 4A, a white dry film precursor was prepared in the same manner as in Example 201, except that Typake CR-97 was used as the colorant Q-1 instead of the inorganic filler, and a dry film with a release liner and protective film was obtained.

[0094] [Examples 401-418, Comparison 401] As shown in Table 5A, a black dry film precursor was prepared in the same manner as in Example 201, except that Mitsubishi Carbon MA100 was used as the coloring agent Q-2 instead of the inorganic filler, and D-2 was used as the dispersant instead of D-1, and a dry film with a release liner and protective film was obtained.

[0095] <Storage modulus (G'80) and loss tangent (tanδ80) at 80°C> Two sets of sheets were prepared by peeling off the protective film from a dry film that had a release liner and protective film attached. The dry films were then laminated together using a laminator set to 90°C to create a laminate of release liner / dry film / release liner. A 1 mm thick dry film was formed by peeling off the release liner from one side of this laminate and sequentially laminating the dry films onto it. For this dry film, the storage modulus (G'80) and loss modulus (G'') at 80°C were measured using a rheometer (TA Instruments, DHR-2) with a φ8 mm measuring probe under the conditions of a strain of 0.1%, a frequency of 1 Hz, and a heating rate of 3°C / min from -50°C to 150°C. The loss tangent (tanδ80) at 80°C was then determined.

[0096] <Coefficient of Dynamic Friction> Each example of the dry film with release liner and protective film was cut to a width of 40 mm, the protective film was removed, and the kinetic friction force of the exposed surface was measured using a friction tester (FRICTION TESTER TR-2, manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with the measurement method specified in JIS K7125, at a temperature of 25°C. A total of five measurements were taken, and the coefficient of kinetic friction was calculated from the average value, which was defined as the coefficient of kinetic friction of the dry film.

[0097] <Evaluation Criteria> Unless otherwise specified, all evaluations were categorized as follows: ◎: Excellent, ○: Good, △: Practical, and ×: Failed to meet target performance. The evaluation results for each example and comparative example are shown in Tables 2B, 3B, 4B, and 5B.

[0098] <Optical density> For Examples 401-418 and Comparative Example 401, the protective film was peeled off from the dry film with the release liner and protective film attached, and the optical density was measured from the exposed dry film side. The optical density was determined using an optical densitometer (361T desktop transmission densitometer: X-RITE). The evaluation criteria were as follows. ◎: Optical density of 3 or higher. ○: Optical density is 1 or greater and less than 3. ×: Optical density is less than 1.

[0099] <Transparency> Dry films with release liners and protective films from Examples 101-116, Comparative Example 101, Examples 201-218, and Comparative Example 201 were cut to a size of 25 mm x 50 mm. The protective films were peeled off, and the exposed dry film surface with the release liner still attached was placed on a 30 mm x 80 mm x 1.1 mm glass plate (blue glass, manufactured by Kawamura Kyuzo Shoten Co., Ltd.). On the release liner surface, a 50 μm thick TPX (Opulan X-44B, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) and a 2.0 mm thick PVC film (Celeb T, manufactured by Okamoto Co., Ltd.) were sequentially laminated as cushioning material, and cardboard was further laminated to prevent sticking. Next, the test piece was pressed from above against the substrate surface at 5 MPa and 100°C for 5 minutes to adhere it to the glass. After pressing, the cushioning material, cardboard, and release liner were peeled off. The haze value and total light transmittance of the dry film were measured using a haze meter (NDH8000, manufactured by Nippon Denshoku Industries Co., Ltd.) on the test specimens. ◎: Haze level 1 or lower, and total light transmittance of 97% or higher. ○: Meets either haze of 1% or less, or total light transmittance of 97% or more. ×: Does not meet the above ◎ or 〇 criteria.

[0100] <Reflectivity> Test specimens were prepared using the same method as for the transparency evaluation in Examples 301-316 and Comparative Example 301. The reflectance of the test specimens in the visible light band (380-780 nm) was measured using a UV-Vis spectrophotometer V-570 (manufactured by JASCO Corporation) at a 25°C atmosphere. ◎: Reflectance in the visible light band is 80% or higher. ○: Reflectance in the visible light band is 60% or more and less than 80%. ×: Reflectance in the visible light band is less than 60%.

[0101] <Sealability> A test substrate was prepared to mimic the uneven surface of the semiconductor element substrate shown in Figure 3 (a glass plate measuring 25 mm x 25 mm, with recesses 200 μm wide, protrusions 5 μm high, and protrusions 200 μm wide formed on one side). Dry films with release liners and protective films for each example and comparative example were cut to a size of 30 mm x 30 mm. The protective films were peeled off, and the exposed dry film surface, with the release liner still attached, was placed on the uneven surface of a glass substrate. Then, a 50 μm thick TPX (Opulan X-44B, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) and a 2.0 mm thick PVC film (Celeb T, manufactured by Okamoto Co., Ltd.) were sequentially laminated on the release liner surface as cushioning material, and cardboard was further laminated to prevent sticking. Next, the test piece was pressed from above against the substrate surface at 5 MPa and 100°C for 20 minutes, filling the uneven surface of the substrate with the dry film and forming a cured sealing layer. After pressing, the release liner, cushioning material, and cardboard were peeled off. The cured material that had protruded from the substrate of the obtained test specimens was removed, exposing the sides of the substrate and allowing observation of the uneven surface. The sealing performance was evaluated by observing 20 arbitrary recesses on the substrate with a laser microscope. A groove was defined as being filled if the cured material adhered tightly to the recess of the substrate without any gaps. The evaluation criteria were as follows. ◎: More than 18 embedded grooves. ○: 17 or fewer embedded grooves, or 15 or more grooves. △: 14 or fewer embedded grooves, or 12 or more embedded grooves. ×: Fewer than 11 embedded grooves.

[0102] <Low temperature curability> One sheet of dry film with release liner and protective film attached for each example and comparative example was prepared, cut to 100mm x 100mm. Then, one sheet of dry film with release liner and protective film attached was prepared, the protective film was peeled off, and the dry film surface with the release liner attached was placed on a glass plate (120mm x 120mm x 1.1mm, blue glass, manufactured by Kawamura Kyuzo Shoten Co., Ltd.). At this time, the glass was marked so that the MD direction of the release liner could be identified. After that, a 50μm thick TPX (Opulan X-44B, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) and a 2.0mm thick PVC film (Celeb T, manufactured by Okamoto Co., Ltd.) were laminated in order as cushioning material on the release liner surface, and then cardboard was laminated to prevent sticking. Next, the specimen was pressed from above against the substrate surface at 5 MPa and 100°C for 20 minutes to form a precursor of the sealing layer on the glass plate. After pressing, the cardboard and cushioning material were peeled off. Subsequently, the precursor with the release liner attached was left to stand for 120 minutes each under conditions of 130°C, 140°C, or 150°C to cure the dry film at each temperature, obtaining a cured product with the release liner attached. Note that MD direction refers to Machine Direction, which is the flow direction (longitudinal direction) of the sheet, and TD direction, which will be described later, refers to Transverse Direction, which is the direction perpendicular to the flow direction.

[0103] For cured products with release liners attached (cured at three different temperatures), the properties that resist shrinkage on the upper surface of the cured product and the adhesion of the cured product to the glass plate were evaluated according to the method described later, and the low-temperature curing properties were comprehensively evaluated according to the following criteria. ◎: Out of 6 evaluation results, there is one or fewer △ ratings and zero × ratings. ○: Out of 6 evaluation results, there are 2 or fewer △ ratings and 0 × ratings. △: Out of 6 evaluation results, 3 or fewer received a △ rating, and 0 received a × rating. ×: One or more of the six evaluation results were marked with an "×".

[0104] [Shrinkage on the upper surface of the cured product] To observe the cross-section of the cured material, the cured material with the release liner still attached was cut in half parallel to the MD direction, 30 mm from the TD end of the release liner. The cross-sections were observed using a laser microscope. As shown in Figure 4, the position of the lower end of the cured material 11' (i.e., the end of the cured material 11' that is in contact with the glass plate 31) was defined as H1, and the position of the upper end of the cured material 11' (i.e., the point of contact between the lower end of the release liner 12 and the cured material 11') was defined as H2. A straight line perpendicular to the glass plate 31 was drawn from H2, and the distance L (μm) between the intersection point with the glass surface and H1 was determined. The shrinkage of the upper side of the cured material 11' was then evaluated according to the following criteria. ◎: The value of L is less than 320 μm. ○: The L value is 320 μm or more and less than 400 μm. △: L value is 400 μm or more and less than 800 μm. ×: The value of L is 800 μm or more.

[0105] [Adhesion] The release liner was peeled off the cured dry film with the release liner still attached. Following JIS K 5600-5-6 (cross-cut method), a cross-cut guide and a utility knife were used to create a 1mm square right-angle grid pattern (25 squares) on the layered cured material. Adhesive tape (CT1835, manufactured by Nichiban Co., Ltd.) was then applied to the grid-cut areas and firmly adhered to the cured material. Within 5 minutes of adhesion, the tape was pulled off at an angle close to 60° for 0.5 to 1.0 seconds. The adhesion was then evaluated according to the following criteria. Note that if the cured dry film peeled off from the glass plate during the protective film peeling stage, it was given a negative rating. ○: 0 squares have been removed. △: 1 to 5 squares have peeled off. ×: 6 to 25 squares have peeled off.

[0106] <Storage stability of dry film> A heating acceleration test was performed on the dry films of each example and comparative example at 40°C for 1 hour, and the sealing performance was evaluated in the same way as the dry films before the heating acceleration test. The evaluation criteria were as follows. ◎: More than 17 embedded grooves. ○: 16 or fewer embedded grooves, 14 or more grooves. △: 13 or fewer embedded grooves, or 12 or more embedded grooves. ×: Fewer than 11 embedded grooves.

[0107] <Handling of dry film> The protective film was peeled off the dry film of each example and comparative example, and the presence or absence of stickiness on the surface of the exposed dry film was evaluated by touch. ○: Non-sticky △: Slightly sticky ×: Sticky items

[0108] <Evaluation of the appearance of the cured material (change in transparency)> For the dry films with release liners and protective films of Examples 101-116, Comparative Example 101, Examples 201-218, and Comparative Example 201, the dry films with release liners were pressed onto a glass plate for 20 minutes at 5 MPa and 100°C using cushioning material and cardboard, similar to the transparency test. After pressing, the cushioning material and cardboard were removed, and the laminated structure of [release liner / dry film / glass plate] was left to stand in a 130°C oven for 2 hours. Next, the release liner was peeled off, and the haze value of the hardened dry film was measured along with the glass plate. The change in haze value before and after heating in a 130°C oven for 2 hours was determined and evaluated according to the following criteria. ○: Haze change is less than 20% △: Haze change is 20% or more, but less than 50%. ×: Haze change is 50% or more Furthermore, for the dry films with release liners and protective films in Examples 301-318, 401-418, and Comparative Examples 301 and 401, transparency could not be measured, so this evaluation was not performed.

[0109] [Table 2A]

[0110] [Table 2B]

[0111] [Table 3A]

[0112] [Table 3B]

[0113] [Table 4A]

[0114] [Table 4B]

[0115] [Table 5A]

[0116] [Table 5B] [Explanation of Symbols]

[0117] 11: Thermal radical polymerizable dry film 11': Cured dry film 12: Release Liner 13: Protective film 20: Optoelectronic semiconductor devices 21: Circuit board 22: Test board

Claims

1. A dry film used for forming a sealing layer by filling the gaps between multiple micro-LEDs formed on a substrate, It contains a radically polymerizable organic compound and a peroxide-based thermal radical polymerization initiator. The peroxide-based thermal radical polymerization initiator has a 10-hour half-life temperature of 60°C or higher and 120°C or lower. The radical polymerizable organic compound contains 95% by mass or more of a radical polymerizable polymer (a) having a glass transition temperature of -50°C or higher and 90°C or lower, Radical polymerizable polymer (a) includes a radical polymerizable acrylic polymer, The loss tangent (tanδ80) at 80°C, obtained by dynamic viscoelasticity measurement, is 0.3 to 0.

7. Thermal radical polymerizable dry film.

2. The storage modulus at 80°C (G'80) obtained by dynamic viscoelasticity measurement is 5 × 10⁻⁶ ４ Pa ~ 5 x 10 ７ The thermal radical polymerizable dry film according to claim 1, characterized in that it is Pa.

3. The thermal radical polymerizable dry film according to claim 2, wherein the coefficient of dynamic friction of the surface of the dry film is 0.5 or less.

4. A heat-radical polymerizable dry film according to claim 1 or 2, having a thickness of 0.5 to 100 μm.

5. The thermal radical polymerizable dry film according to claim 4, wherein the 10-hour half-life temperature of the peroxide-based thermal radical polymerization initiator is 80°C or higher and 110°C or lower.

6. The thermal radical polymerizable dry film according to claim 4, wherein the amount of the peroxide-based thermal radical polymerization initiator blended is 0.01 to 20% by mass of the total solid content.

7. An electronic device comprising a cured product of a thermal radical polymerizable dry film according to claim 5.

Images