Curable composition and silicone resin

Abstract

The present invention provides a curable composition that can suppress shrinkage after accelerated lightfastness testing and form a silicone resin with excellent adhesion, lightfastness, heat resistance, and durability. [Solution] A curable composition comprising a curable silicone and a boron compound selected from the group consisting of boronic acid, boronic acid ester, boric acid, boric acid ester, and boroxine derivatives thereof, wherein the content ratio of silicon Si to boron B (Si / B) in the cured product obtained by heating the curable composition at 100°C for 60 minutes is greater than 10 and less than or equal to 60.

Description

[Technical Field]

[0001] This disclosure relates to a curable composition and a silicone resin. [Background technology]

[0002] As a light-emitting device that emits ultraviolet light, a light-emitting element, a lens, and an adhesive layer that bonds the light-emitting element and the lens have been developed. From the viewpoint of improving output such as light extraction efficiency, an adhesive layer that has sufficient adhesion, can transmit ultraviolet light, and is light-resistant to ultraviolet light is being investigated.

[0003] To date, adhesive compositions for foldable displays have been reported, comprising: a first adhesive containing a first silicone rubber (gum) with a peeling force to a glass substrate of 10 gf / in or less, measured at a peeling speed of 0.3 m / min and a peeling angle of 180 degrees; a second adhesive containing a second silicone rubber (gum) and a second MQ resin, with a peeling force to a glass substrate measured at a peeling speed of 0.3 m / min and a peeling angle of 180 degrees, measured in the range of 200 gf / in to 400 gf / in; and one additive selected from the group consisting of borane compounds, borate compounds, and mixtures thereof (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2019-527268 [Overview of the project] [Problems that the invention aims to solve]

[0005] One aspect of this disclosure aims to provide a curable composition that can suppress shrinkage after accelerated lightfastness testing and form a silicone resin with excellent adhesion, lightfastness, heat resistance, and durability.

Means for Solving the Problem

[0006] The curable composition according to one aspect of the present disclosure is a curable composition containing a curable silicone and a boron compound selected from the group consisting of boric acid, boronic acid ester, boric acid, boric acid ester, and boroxine derivatives thereof, wherein the content ratio (Si / B) of silicon Si to boron B in the cured product obtained by heating the curable composition at 100 °C for 60 minutes is more than 10 and 60 or less.

Advantages of the Invention

[0007] According to one aspect of the present disclosure, it is possible to provide a curable composition capable of suppressing shrinkage after a super-accelerated light resistance test and forming a silicone resin excellent in adhesiveness, light resistance, heat resistance, and durability.

Brief Description of the Drawings

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing an ultraviolet light-emitting device having a silicone resin according to an embodiment.

Embodiments of the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and the description thereof may be omitted. In the specification, "~" indicating a numerical range means including the numerical values described before and after it as the lower limit value and the upper limit value.

[0010] (Curable Composition) The curable composition of the present embodiment contains a curable silicone and a boron compound selected from the group consisting of boric acid, boronic acid ester, boric acid, boric acid ester, and boroxine derivatives thereof, and further contains other components as necessary.

[0011] The content ratio of silicon Si to boron B (Si / B) in the cured product obtained by heating the curable composition at 100°C for 60 minutes is more than 10 and 40 or less, preferably 15 or more and 35 or less.

[0012] By the way, the silicone resin is transparent and has the advantages of excellent light transmittance and ultraviolet transmittance. However, for example, in the ultraviolet light emitting device 1 shown in FIG. 1 described later, the shorter the emission peak wavelength of the ultraviolet light emitted by the light emitting element 2, the more problems there are that the conventional organic material forming the adhesive layer 5 (for example, a silicone resin having an organic group) deteriorates. In addition, the stronger the radiant flux of the light emitting element 2 is increased to improve the output, the easier it is for the adhesive layer 5 to deteriorate, and there is a problem that cracks occur in the adhesive layer. If the adhesive layer 5 deteriorates, the light transmittance decreases, and the light extraction efficiency decreases.

[0013] The present inventors have found that a curable composition containing a curable silicone, a boron compound selected from the group consisting of boric acid, boronic acid ester, boric acid, boric acid ester, and boroxine derivatives thereof, and the content ratio of silicon Si to boron B (Si / B) in the cured product obtained by heating the curable composition at 100°C for 60 minutes is more than 10 and 60 or less, can suppress shrinkage after the super-accelerated light resistance test, and can provide a curable composition capable of forming a silicone resin excellent in adhesiveness, light resistance, heat resistance, and durability, and a silicone resin.

[0014] Here, when the siloxane components of the curable silicone condense, siloxane bonds -O-Si-O- and Si-mediated crosslinks are formed. Simultaneously, the inclusion of a boron compound in the curable composition introduces crosslinks via -OBO- and B. This increases the proportion of inorganic components in the resulting silicone resin, which is thought to suppress radical generation due to ultraviolet light and radiation, and the resulting degradation (carbonization and discoloration of organic components, and shrinkage of the resin due to the formation of new crosslinks). Furthermore, compared to methods that introduce siloxane compounds such as tetraethoxysilane, which can form four crosslinks via oxygen atoms, as inorganic components, the boron compound forms two or three crosslinks per atom, so even when added as an inorganic component, the curable composition before degradation is less likely to become brittle. Therefore, it is possible to provide a curable composition that can form a silicone resin with excellent adhesion, light resistance, heat resistance, and durability even in environments exposed to ultraviolet light, radiation, and heat.

[0015] -Curing silicone- Curable silicones contain organosiloxy units. Organosiloxy units include monofunctional organosiloxy units called M units, difunctional organosiloxy units called D units, trifunctional organosiloxy units called T units, and tetrafunctional organosiloxy units called Q units. Although Q units do not have an organic group bonded to a silicon atom (an organic group having a carbon atom bonded to a silicon atom), in this specification they are considered organosiloxy units (silicon-bonded units). Monomers that form M units, D units, T units, and Q units are also referred to as M monomers, D monomers, T monomers, and Q monomers, respectively.

[0016] In organosiloxy units, a siloxane bond is a bond in which two silicon atoms are connected via one oxygen atom. Therefore, the oxygen atom per silicon atom in a siloxane bond is considered to be 1 / 2, and in the formula O 1 / 2It is expressed as follows. More specifically, for example, in one D unit, one silicon atom is bonded to two oxygen atoms, and each oxygen atom is bonded to a silicon atom of another unit. Therefore, the formula is -O 1 / 2 -(R)2Si-O 1 / 2 -(where R represents a hydrogen atom or an organic group). Due to the presence of two O 1 / 2 the D unit is (R)2SiO 2 / 2 (In other words, (R)2SiO) and is usually expressed as such.

[0017] The curable silicone preferably contains an organosiloxy unit (T unit) represented by RSiO 3 / 2 (wherein R represents an organic group), and further, if necessary, an organosiloxy unit (Q unit) represented by SiO 4 / 2 , an organosiloxy unit (M unit) represented by (R)3SiO 1 / 2 (wherein R represents an organic group), and other siloxane components such as an organosiloxy unit (D unit) represented by (R)2SiO 2 / 2 (wherein R represents an organic group) may be contained.

[0018] In the following description, the oxygen atom O bonded to another silicon atom * is an oxygen atom that bonds between two silicon atoms and means the oxygen atom in the bond represented by Si-O-Si. Therefore, O * exists one between the silicon atoms of two organosiloxy units.

[0019] The T unit means an organosiloxy unit represented by RSiO 3 / 2 (R represents a hydrogen atom or an organic group). That is, the T unit has one silicon atom, one hydrogen atom or organic group bonded to the silicon atom, and three oxygen atoms O * bonded to other silicon atoms.

[0020] As the siloxane component having a T unit, a silicone resin having a T unit is preferred. The organic group R in the T unit is not particularly limited and can be appropriately selected depending on the purpose, but a methyl group is preferred.

[0021] The term "Q unit" refers to the organosiloxy unit represented by SiO2. In other words, a Q unit has one silicon atom and an oxygen atom bonded to another silicon atom. * This is a unit having four Q units. As the siloxane component having Q units, low molecular weight siloxane components (also called oligomers) are preferred, and may be linear or cyclic.

[0022] The unit M is (R)3SiO 1 / 2 This represents an organosiloxy unit. Here, R represents a hydrogen atom or organic group. The number after (R) (in this case, 3) means that three hydrogen atoms or organic groups are bonded to the silicon atom. In other words, the M unit consists of one silicon atom, three hydrogen atoms or organic groups, and one oxygen atom. * It has the following characteristics. More specifically, the M unit consists of three hydrogen atoms or organic groups bonded to one silicon atom, and one oxygen atom O bonded to one silicon atom. * It has.

[0023] The unit D is (R)2SiO 2 / 2 This refers to an organosiloxy unit represented as (R represents a hydrogen atom or organic group). In other words, a D unit has one silicon atom, two hydrogen atoms or organic groups bonded to that silicon atom, and an oxygen atom O bonded to another silicon atom. * It is a unit that has two of them.

[0024] Examples of organic groups include monovalent hydrocarbon groups such as alkyl groups, aryl groups, and aralkyl groups; and halogen-substituted monovalent hydrocarbon groups. Among these, unsubstituted or halogen-substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms are preferred, and unsubstituted or halogen-substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms are more preferred.

[0025] Examples of alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl groups. Examples of aryl groups include phenyl, tolyl, xylyl, and naphthyl groups. Examples of aralkyl groups include benzyl and phenethyl groups. Examples of halogen-substituted monovalent hydrocarbon groups include halogenated alkyl groups, halogenated aryl groups, and halogenated aralkyl groups. Examples of halogenated alkyl groups include chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl groups.

[0026] In this specification, the total organosiloxy units constituting the silicone resin mean the sum of M units, D units, T units, and Q units. The proportion (mol%) of the number of M units, D units, T units, and Q units is: 29 It can be calculated from the peak area ratio value obtained by Si-NMR.

[0027] The curable silicone preferably has a T unit content of 60 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, relative to the total organosiloxy units, in order to reduce the organic group content. There is no particular upper limit, but it is often 100 mol% or less.

[0028] -Boron compounds- The boron compound is a boron compound selected from the group consisting of boronic acid, boronic acid ester, boric acid, boric acid ester, and boroxine derivatives thereof. In one embodiment, it is preferable that the boron compound is selected from the group consisting of boric acid, boric acid ester, and boroxine derivatives thereof, because there are many bonds that can participate in the crosslinking of boron B, and crosslinking proceeds more effectively. These may be used individually or in combination of two or more.

[0029] Boric acid is represented by the chemical formula B(OH)3, and boric acid esters are compounds represented by the chemical formula B(OR')3. Boronic acid is represented by the chemical formula R″B(OH)2, and boronic acid esters are compounds represented by the chemical formula R″B(OR')2.

[0030] In the manufacturing process of silicone resin, when the curable composition is cured, some of the siloxane bonds are replaced with -OBO-. Here, if the boron compound has an organic group R' in the ester portion, R' is not incorporated into the synthesized silicone resin, but if the boron compound has an organic group R'' that is directly bonded to boron B, R'' is introduced into the synthesized silicone resin.

[0031] When R' and R'' are present in groups of two or more, they may be the same or different from each other, and each may independently be a monovalent hydrocarbon group such as an alkyl group, aryl group, or aralkyl group; or a halogen-substituted monovalent hydrocarbon group.

[0032] In R' and R'' above, examples of alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl groups. Examples of aryl groups include phenyl, tolyl, xylyl, and naphthyl groups. Examples of aralkyl groups include benzyl and phenethyl groups. Examples of halogen-substituted monovalent hydrocarbon groups include halogenated alkyl groups, halogenated aryl groups, and halogenated aralkyl groups. Examples of halogenated alkyl groups include chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl groups.

[0033] Among these, R' is preferably a monovalent hydrocarbon group having 1 to 12 carbon atoms, and more preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms. R'' is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group.

[0034] Boroxine derivatives are derivatives synthesized by the dehydration condensation of the corresponding boric acid and boronic acid. Because they exist in equilibrium with the corresponding boric acid and boronic acid, they function as those compounds. For example, boroxine is a heterocyclic compound represented by the chemical formula B3H3O3 and is a boroxine derivative of boric acid. Trimethoxyboroxine is a boroxine derivative of methylboronic acid.

[0035] [Ratio of silicon (Si) to boron (B) in cured products] The silicon (Si) content ratio (Si / B) in the cured product obtained by heating the curable composition at 100°C for 60 minutes is greater than 10 and 60 or less, preferably greater than 10 and 50 or less, more preferably greater than 10 and 40 or less, and even more preferably between 15 and 35.

[0036] The silicon (Si) content ratio (Si / B) in cured products and silicone resins can be measured by spectral analysis using X-ray electron spectroscopy (XPS). Specifically, using an X-ray photoelectron spectrometer (e.g., ULVAC PHI, PHI5000 VersaProbeIII), when the C1s peak top is set to 284.38 eV, the silicon (Si) content ratio (Si / B) can be determined from the spectrum of the B1s peak between 190 eV and 195 eV, and the Si2p peak between 99 eV and 105 eV.

[0037] Here, the peak top of the C1s peak corresponds to CH bonds and C-Si bonds, the spectrum of the B1s peak between 190eV and 195eV corresponds to BO bonds, and the spectrum of the Si2p peak between 99eV and 105eV corresponds to Si-O bonds and Si-C bonds.

[0038] Furthermore, because the signal-to-noise ratio (S / N ratio) of the B1s peak is very small, the spectrum corresponding to BO binding that may be included in the B1s peak can be measured and evaluated by performing statistical analysis. Specifically, the spectrum corresponding to BO binding between 190eV and 195eV can be evaluated as statistically significant if the difference between the maximum and minimum intensity in the 190eV to 195eV range is greater than three times the standard deviation σ in the 197eV to 203eV range.

[0039] -Other ingredients- Other components include metal elements; solvents; silane coupling agents; stabilizers; and other additives.

[0040] -Metal elements- The curable composition preferably further contains at least one metallic element selected from 3d transition metals, 4d transition metals, lanthanide metals, bismuth, aluminum, tin, and zinc. This suppresses the generation of bubbles in the silicone resin cured with the curable composition during high-temperature heat treatment (e.g., 500°C to 600°C) under an inert gas atmosphere. The reason (mechanism) for this effect is not clear, but it is thought that the generation of volatile components is reduced by the metal element crosslinking the parts that decompose as the polymerization reaction progresses in the silicone resin cured with the curable composition.

[0041] Among metal elements, 3d transition metals such as Ti, Mn, Fe, Co, Ni, and Cu, and zinc (Zn) are preferred for further reducing bubbles. These may be used individually or in combination of two or more. The metal element may be in the form of a metal, an ion, a compound, or a complex.

[0042] The content of the aforementioned metal element is preferably 0.02% to 1.5% by mass, more preferably 0.03% to 1.0% by mass, even more preferably 0.04% to 0.3% by mass, and particularly preferably 0.06% to 0.3% by mass, relative to the total amount of the curable composition, in terms of reducing bubbles.

[0043] The method for measuring metal elements in curable compositions and silicone resins is not particularly limited, and known methods can be employed, such as ICP emission spectrometry (ICP-AES) and ICP mass spectrometry (ICP-MS). Examples of equipment used in the above methods include the inductively coupled plasma emission spectrometer PS3520UVDDII (Hitachi High-Technologies Corporation) and the inductively coupled plasma (triple quadrupole) mass spectrometer Agilent 8800 (Agilent Technologies Corporation).

[0044] The curable composition may be in liquid or sol form, or in film or sheet form, but a film form is preferred from the viewpoint of ease of handling. The film-like curable composition (hereinafter sometimes referred to as the curable composition film) formed on a release substrate can be transferred to an optical glass component such as a light-emitting element or a lens, and then cured after being deformed to conform to the component as needed.

[0045] When the composition is in film form, there are no particular restrictions on the average thickness of the film-like curable composition, and it can be appropriately selected depending on the purpose. However, a thickness of 5 μm or less is preferred, and a thickness of 4 μm or less is more preferred in terms of reducing air bubbles. Furthermore, a thickness of 0.5 μm or more is preferred, and a thickness of 1 μm or more is more preferred in terms of adhesion.

[0046] There are no particular limitations on the method for forming a film-like curable composition, and known methods can be appropriately selected depending on the purpose. For example, one method involves applying a liquid or sol-like curable composition onto a release substrate such as a release film and drying it.

[0047] Methods for imparting a liquid or sol-like curable composition include, for example, spin coating, spray coating, bar coating, gravure coating, screen printing, and inkjet coating. Methods for drying the liquid or sol-like curable composition include removing any solvent present, for example, drying at 50°C to 100°C for 20 to 50 minutes.

[0048] (Silicone resin) The silicone resin of this embodiment is a boron-containing silicone resin in which the silicon (Si) content ratio (Si / B) to boron (B) is greater than 10 and less than or equal to 60, and in the spectrum obtained by X-ray electron spectroscopy (XPS), when the C1s peak top is set to 284.38 eV, a spectrum corresponding to the BO bond between 190 eV and 195 eV is detected.

[0049] The silicone resin of this embodiment can be suitably manufactured by curing the curable composition of this embodiment. There are no particular restrictions on the method of curing the curable composition, and thermocuring, photocuring, etc. can be appropriately selected depending on the purpose. For example, the silicone resin can be synthesized by curing the curable composition using a film-like curable composition or by heating the curable composition at 80°C to 120°C for 30 to 100 minutes. In addition, in order to obtain sufficient adhesive strength, autoclaving (heating and pressurizing treatment) or pressurizing treatment may be performed when bonding the members to be bonded or after bonding. Furthermore, the silicone resin can be aged by irradiating it with ultraviolet light after bonding. Heating treatment, autoclaving treatment and aging treatment may be carried out in an atmospheric pressure atmosphere or in an inert gas atmosphere.

[0050] Typically, silicone resins are obtained by curing (cross-linking) a curable silicone. In other words, silicone resin is a cured product of a curable silicone. The silicone resin of this embodiment is characterized by further having BO bonds derived from boron compounds at a specific Si / B content ratio. Curable silicones are classified into condensation reaction type silicones, addition reaction type silicones, ultraviolet curing type silicones, and electron beam curing type silicones according to their curing mechanism, and any of them can be used.

[0051] [Ratio of silicon (Si) to boron (B) in silicone resin] The silicon (Si / B) content ratio to boron (B) in the silicone resin is greater than 10 and 60 or less, preferably greater than 10 and 50 or less, more preferably greater than 10 and 40 or less, and even more preferably between 15 and 35. The silicon (Si) content ratio to boron (B) in the silicone resin can be determined in the same manner as the silicon (Si) content ratio to boron (B) in the cured product of the curable composition described above.

[0052] [Identification of BO bonds in silicone resins] In the X-ray electron spectroscopy (XPS) spectrum of the aforementioned silicone resin, when the C1s peak top is set to 284.38 eV, a spectrum corresponding to a BO bond between 190 eV and 195 eV is detected. In other words, the aforementioned silicone resin is a boron-containing silicone resin having a BO bond.

[0053] [Identification of BC bonds in silicone resins] Furthermore, in one embodiment, it is preferable that, in the spectrum obtained by X-ray electron spectroscopy (XPS), when the C1s peak top is set to 284.38 eV, the spectrum corresponding to BC bonds between 185 eV and 190 eV is substantially undetectable. In other words, it is preferable that the silicone resin is a silicone resin that substantially does not have BC bonds. In the curable composition, an embodiment in which the boron compound is selected from the group consisting of boric acid, boric acid esters, and boroxine derivatives thereof corresponds to this embodiment. Alternatively, an embodiment in which the boron compound substantially does not have an organic group R'' that directly bonds to boron B, or in which the organic group R'' is substantially not introduced into the silicone resin, also corresponds to this embodiment.

[0054] Furthermore, because the signal-to-noise ratio (S / N ratio) of the B1s peak is very small, spectra corresponding to BO bonds and BC bonds that may be included in the B1s peak can be measured and evaluated by statistical analysis. Specifically, spectra corresponding to BO bonds between 190eV and 195eV can be measured if the difference between the maximum and minimum intensities in the 190eV-195eV range is greater than three times the standard deviation σ of the 197eV-203eV range (greater than 3σ), and this is considered statistically significant. In addition, spectra corresponding to BC bonds between 185eV and 190eV can be considered virtually undetectable if the difference between the maximum and minimum intensities in the 185eV-190eV range is less than or equal to two times the standard deviation σ of the 197eV-203eV range (less than or equal to 2σ).

[0055] [Application] The curable composition of this embodiment is a curable composition that can suppress shrinkage after ultra-accelerated lightfastness testing and can form a silicone resin with excellent adhesion, lightfastness, heat resistance, and durability. The silicone resin of this embodiment is a silicone resin that can suppress shrinkage after ultra-accelerated lightfastness testing and has excellent adhesion, lightfastness, heat resistance, and durability. Therefore, the curable composition and silicone resin of this embodiment can be suitably used as adhesive members used in environments exposed to ultraviolet rays, radiation, and heat, and can be suitably used as, for example, ultraviolet light-emitting element members, exterior coating members applied to surfaces in contact with the outside air, and aerospace equipment members. In one embodiment, it can be suitably used as an adhesive layer or adhesive member for an ultraviolet light-emitting element.

[0056] -Ultraviolet light emission device- An embodiment of this design in which the silicone resin is used as an adhesive layer for an ultraviolet light-emitting device will be described. The ultraviolet light-emitting device includes, for example, a light-emitting element, an optical glass member, and the adhesive layer that adheres the light-emitting element and the optical glass member, and may further include other members as needed.

[0057] Referring to Figure 1, an ultraviolet light-emitting device 1 according to one embodiment will be described. The light-emitting device 1 comprises a light-emitting element 2, a lens 3, and an adhesive layer 5 that bonds the light-emitting element 2 and the lens 3. The lens 3 is an example of an optical glass member.

[0058] <hibi> The light-emitting element 2 is not particularly limited as long as it is an element that emits light including ultraviolet light, and can be appropriately selected according to the purpose, but an element that emits light with ultraviolet light as its emission peak wavelength is preferred. Light is transmitted in this order between a part of the light-emitting element 2, the adhesive layer 5, and the lens 3. The ultraviolet light is preferably 200 nm to 320 nm in wavelength, more preferably UVC (e.g., 200 nm to 280 nm) or 240 nm to 290 nm, and may also be 265 nm, 280 nm, etc. The "emission peak wavelength" is the wavelength with the highest output value in the spectral distribution of the emitted light. The radiant flux of the light-emitting element 2 is, for example, more than 20 mW, preferably 35 mW or more, and more preferably 40 mW or more. The radiant flux of the light-emitting element 2 may be 120 mW or less from the viewpoint of the heat dissipation of the light-emitting element 2. Radiant flux is the radiant energy emitted per unit time. Radiant flux is measured in accordance with CIE 127:2007.

[0059] The light-emitting element 2 has, for example, a substrate 22 and a semiconductor layer 23. The light-emitting element 2 has, for example, a flip-chip structure. When the light-emitting element 2 has a flip-chip structure, the light generated in the semiconductor layer 23 is emitted through the substrate 22. The substrate 22 is a transparent substrate that transmits light. The surface of the substrate 22 facing the lens 3 is the light-emitting surface 21 of the light-emitting element 2.

[0060] The substrate 22 is made of, for example, a sapphire substrate or an aluminum nitride substrate. An aluminum nitride substrate is a substrate made of a single crystal of aluminum nitride. The sapphire substrate or aluminum nitride substrate is a transparent substrate that transmits ultraviolet light. The thickness t of the substrate 22 is, for example, 0.05 mm to 2 mm.

[0061] The semiconductor layer 23 is provided on the side opposite to the lens 3 with respect to the substrate 22. The semiconductor layer 23 emits light when a voltage is applied. The electrodes for applying voltage to the semiconductor layer 23 are not shown, but are formed on the side opposite to the substrate 22 with respect to the semiconductor layer 23 so as not to block the light traveling from the semiconductor layer 23 to the substrate 22. Therefore, a decrease in the light extraction efficiency can be prevented.

[0062] The light-emitting element 2 may be bonded to the mounting substrate via solder bumps. The mounting substrate is, for example, a ceramic substrate made of an aluminum nitride sintered body, an aluminum oxide sintered body, or LTCC (Low Temperature Co-fired Ceramics) with electrodes formed on it.

[0063] The surface roughness Ra of the light-emitting surface 21 of the light-emitting element 2 is, for example, 0.01 nm to 5 nm. If a fine uneven structure is formed on the light-emitting surface 21 to improve the efficiency of ultraviolet light extraction, the surface roughness Ra of the light-emitting surface 21 is 5 nm to 50 nm. The surface roughness Ra of the opposing surface 31 of the lens 3 is, for example, 0.01 nm to 5 nm. The surface roughness Ra is the arithmetic mean roughness as described in JIS B0601:2001.

[0064] <Optical glass components> Lens 3 suppresses total internal reflection of light and improves the efficiency of light extraction. Lens 3 has an opposing surface 31 that faces the light-emitting surface 21 of the light-emitting element 2, and a convex curved surface 32 that faces in the opposite direction to the opposing surface 31. Ultraviolet light emitted by the light-emitting element 2 is incident on the opposing surface 31 and exits from the convex curved surface 32. The convex curved surface 32 is a dome-shaped curved surface whose center protrudes more than its periphery.

[0065] Lens 3 may be either a spherical or aspherical lens. Although not shown in the diagram, lens 3 may have a flange that protrudes radially outward from the periphery of the convex curved surface 32.

[0066] Although not shown in the diagram, the convex surface 32 of the lens 3 may have irregularities that prevent reflection of light generated by the light-emitting element 2. The irregularities of the convex surface 32 may have, for example, a moth-eye structure, which prevents light traveling from the inside to the outside of the lens 3 from being reflected back into the inside of the lens 3, thereby improving the efficiency of light extraction.

[0067] Although not shown in the diagram, the light-emitting device 1 may be equipped with an anti-reflective coating on the convex curved surface 32 of the lens 3. The anti-reflective coating prevents light traveling from the inside of the lens 3 to the outside from being reflected back into the inside of the lens 3, thereby improving the efficiency of light extraction. A general-purpose anti-reflective coating is used.

[0068] Although not shown in the diagram, the convex surface 32 of the lens 3 may have irregularities that scatter the ultraviolet light generated by the light-emitting element 2. The irregularities of the convex surface 32 scatter the ultraviolet light emitted from the convex surface 32, thereby directing the ultraviolet light towards a wider area.

[0069] The material of lens 3 is, for example, oxide glass. Oxide glass can be processed using various methods such as thermoforming or grinding and polishing, and a processing method suitable for the shape of lens 3 can be selected. Examples of oxide glass include soda-lime glass, alkali-free glass, chemically strengthened glass, or lanthanum borate glass. To minimize the loss of ultraviolet light by lens 3, a material with a low ultraviolet light absorption rate is suitable as the material of lens 3, and the material of lens 3 is preferably quartz, quartz glass, or sapphire.

[0070] <Adhesive layer> The adhesive layer 5 contains the silicone resin of this embodiment. The silicone resin is a boron-containing silicone resin in which the silicon Si content ratio (Si / B) to boron B is greater than 10 and less than or equal to 60, and in the spectrum obtained by X-ray electron spectroscopy (XPS), when the C1s peak top is set to 284.38 eV, a spectrum corresponding to the BO bond between 190 eV and 195 eV is detected.

[0071] The adhesive layer 5 is preferably made of the silicone resin of this embodiment. The adhesive layer 5 can be suitably prepared by curing the curable composition of this embodiment.

[0072] [Composition of the adhesive layer] The adhesive layer 5 adheres the light-emitting surface 21 of the light-emitting element 2 to the opposing surface 31 of the lens 3, with the two surfaces facing each other. Preferably, the light-emitting surface 21 of the light-emitting element 2 and the opposing surface 31 of the lens 3 each have a flat surface in at least the overlapping region. The opposing surface 31 of the lens 3 may be larger than the light-emitting surface 21 of the light-emitting element 2 and may have a curved surface in the region that extends beyond the light-emitting surface 21.

[0073] The interface between the adhesive layer 5 and the light-emitting element 2 is called the first interface. In this embodiment, the first interface is the entire light-emitting surface 21, but it may also be a part of the light-emitting surface 21. The interface between the adhesive layer 5 and the lens 3 is called the second interface. In this embodiment, the second interface is the entire opposing surface 31, but it may also be a part of the opposing surface 31.

[0074] There are no particular restrictions on the average thickness of the adhesive layer 5, and it can be appropriately selected depending on the purpose, but it is preferably 5 μm or less, and more preferably 4 μm or less in terms of reducing air bubbles. Furthermore, in terms of adhesion, it is preferably 0.5 μm or more, and more preferably 1 μm or more.

[0075] Maximum thickness T in the adhesive layer M and minimum thickness T m The difference (T M -T m There are no particular restrictions on the particle size, and it can be selected appropriately depending on the purpose, but a particle size of 0.5 μm or less is preferred, and a particle size of 0.4 μm or less is more preferred.

[0076] The thickness of the adhesive layer 5 can be determined by removing the glass lens from the light-emitting element, making scratches at five arbitrary locations on the joint of the adhesive layer 5 remaining on the bottom surface of the light-emitting element 2 and / or lens 3, and measuring the height of the step in the scratches using a non-contact surface texture measuring device (e.g., PF-60, manufactured by Mitaka Kohki Co., Ltd.). The average thickness of the adhesive layer 5 can be determined by measuring the thickness of the adhesive layer at five or more arbitrary points and calculating the average value.

[0077] Maximum thickness T in the adhesive layer M and minimum thickness T m The difference (T M -T m ) is the maximum and minimum thickness of the adhesive layer 5 measured at any 5 or more points, respectively, with maximum thickness T. M and minimum thickness T m As, the maximum thickness T M and minimum thickness T m The difference (T M -T m This can be determined by calculating ( ).

[0078] The surface roughness of the bonding surface between the adhesive layer 5 and the light-emitting element 2 is not particularly limited and can be appropriately selected according to the purpose, but 0.01 nm to 50 nm is preferred. Surface roughness can be measured by measurement methods using, for example, a non-contact surface / layer cross-sectional shape measurement system (e.g., Vertscan R3300-lite, manufactured by Ryoka Systems Co., Ltd.), an atomic force microscope (AFM), a laser microscope (e.g., UV-X3000, manufactured by Keyence Corporation), or a non-contact surface property measurement device (e.g., PF-60, manufactured by Mitaka Kohki Co., Ltd.).

[0079] There are no particular restrictions on the indentation modulus of the adhesive layer, and it can be appropriately selected depending on the purpose, but 1 GPa to 10 GPa is preferred. The indentation modulus can be measured using an ultra-micro indentation hardness tester (e.g., ENT-NEXUS, manufactured by Elionix Co., Ltd.) by setting the load so that the indentation depth is 1 / 10 or less of the thickness of the adhesive layer.

[0080] [Manufacturing method for light-emitting devices] There are no particular limitations on the manufacturing method of the light-emitting device, and a known method can be appropriately selected depending on the purpose. For example, one method involves placing a curable composition between an optical glass member and a light-emitting element, and then heating it to cure the curable composition, thereby bonding the light-emitting element and the optical glass member together.

[0081] As for the method of arranging the curable composition, a liquid or sol-like curable composition may be applied, or a film-like curable composition may be arranged by transfer or the like, and any of these methods can be suitably selected.

[0082] In order to bond the optical glass member and the light-emitting element 2 with sufficient adhesive force using the adhesive layer 5, it is preferable to thoroughly clean the bonding surfaces of the optical glass member and the light-emitting element 2. The cleaning method is not particularly limited. For example, it can be cleaned using hydrocarbon solvents such as ethanol and acetone, fluorine-based solvents such as AS-300 (manufactured by AGC Inc.), or aqueous cleaning agents such as alkaline detergents. Also, the adhesive force can be improved by subjecting the bonding surface to a surface activation treatment. For example, UV ozone treatment, atmospheric pressure plasma treatment, excimer UV treatment, corona treatment, etc. can be used.

[0083] There is no particular limitation on the method of bonding the optical glass member and the light-emitting element 2, and it can be appropriately selected according to the purpose. For example, methods such as bonding the optical glass member and the light-emitting element 2 under atmospheric pressure, reduced pressure, or vacuum can be mentioned.

Example

[0084] Hereinafter, the experimental data will be described. The following Examples 1 to 3 are examples, and the following Example 4 is a comparative example.

[0085] [Example 1] <Preparation of siloxane component having T unit> Into a 1 L flask, trimethoxysilane (179 g), toluene (300 g), and acetic acid (5 g) were added. After stirring the mixture at 25°C for 20 minutes, it was further heated to 60°C and reacted for 12 hours. After cooling the obtained reaction crude liquid to 25°C, the reaction crude liquid was washed 3 times with water (300 g). Chlorotrimethylsilane (70 g) was added to the washed reaction crude liquid. After stirring the mixture at 25°C for 20 minutes, it was further heated to 50°C and reacted for 12 hours. After cooling the obtained reaction crude liquid to 25°C, the reaction crude liquid was washed 3 times with water (300 g). Toluene was distilled off under reduced pressure from the washed reaction crude liquid to make it into a slurry state, and then dried overnight in a vacuum dryer to obtain a white T-form silicone resin as a siloxane component having a T unit.

[0086] <Production of curable composition> 80 parts by mass of the obtained T-isomer silicone resin and 200 parts by mass of ethanol (manufactured by Junsei Chemical Co., Ltd.) as a solvent were added to a glass bottle containing a stirring bar. Next, 1 part by mass of pyruvic acid (manufactured by Junsei Chemical Co., Ltd.) diluted with 1 part by mass of isopropyl alcohol (manufactured by Junsei Chemical Co., Ltd.), 20 parts by mass of triisopropyl borate (manufactured by Tokyo Chemical Industry Co., Ltd.) as a boron compound, and 2 parts by mass of pure water to promote the hydrolysis of triisopropyl borate were added to the glass bottle. The resulting mixture was stirred for more than 3 hours to obtain mixture A.

[0087] Separately, a glass bottle containing a stirring bar was prepared, and 27 parts by mass of ethanol, 1.25 parts by mass of a toluene solution of 8% by mass of 2-ethylhexanoate cobalt (Nikka Octic Cobalt, Nippon Chemical Industrial Co., Ltd.; containing 0.1 parts by mass of 2-ethylhexanoate cobalt), 5 parts by mass of toluene (manufactured by Junsei Chemical Co., Ltd.), and 27 parts by mass of ethanol (manufactured by Junsei Chemical Co., Ltd.) were added and stirred. This mixture was then added to mixture A and stirred to prepare the curable composition of Example 1.

[0088] <Coating of curable compositions> The surface of a glass substrate (DragonTrail glass, size: 5cm x 5cm, AGC Inc.) was pre-cleaned with an organic solvent and then UV-irradiated. Drops of the resulting curable composition were dropped onto the surface of the glass substrate, and then the curable composition was coated using a spin coater (Opticoat MS-A200, manufactured by Misaka Corporation) under the following coating conditions: accelerated to 1000 rpm in 2 seconds, maintained at 1000 rpm for 20 seconds, and then decelerated to 0 rpm in 2 seconds.

[0089] <Manufacturing of silicone resin> A curable composition coated onto a glass substrate was dried and cured at 100°C for 60 minutes to suppress the precipitation of boric acid, thereby producing the cured silicone resin of Example 1.

[0090] <Rating> The following procedure was used to evaluate the spectral analysis by X-ray electron spectroscopy (XPS) and the shrinkage after accelerated photofastness testing. The results are shown in Table 1.

[0091] [XPS Spectrum Analysis] Using an X-ray photoelectron spectrometer (ULVAC PHI, PHI5000 VersaProbeIII), XPS spectrum measurements were performed under the following conditions with each silicone resin formed on a glass substrate as a sample.

[0092] - Conditions - Analysis area: 100 μm in diameter Detection angle: 45° with respect to the sample surface X-ray source: Monochromatic Al Kα ray X-ray conditions: 100 μm in diameter, 25 W, 15 kV Pass energy: 224.0 eV Step energy: 0.4 eV / step Step time: 20 ms / step Monitored peaks: B1s, Si2p Integration times: 128 times To exclude the influence of sample contamination, the inside about 1 nm in the thickness direction of the sample was measured by Ar ion sputtering.

[0093] Using analysis software (ULVAC PHI, Multipak), the measured XPS spectra were analyzed to evaluate the content ratio (Si / B), the presence or absence of B-O bonds, and the presence or absence of B-C bonds. The Shirley method was applied for background removal of the spectra, and the relative sensitivity coefficients recorded in the analysis software were used.

[0094] [Content Ratio of Silicon Si to Boron B in Silicone Resin] In the measured XPS spectrum, when the C1s peak top was set to 284.38 eV, the content ratio (Si / B) of silicon Si to boron B was determined from the spectra between 190 eV and 195 eV in the B1s peak and the spectra between 99 eV and 105 eV in the Si​2p peak.

[0095] [Identification of B-O Bonds in Silicone Resin] In the measured XPS spectra, the presence or absence of spectra corresponding to BO binding between 190 eV and 195 eV was evaluated, with the C1s peak top set to 284.38 eV. Here, since the signal-to-noise ratio (S / N ratio) of the B1s peak is very small, the presence or absence of spectra corresponding to BO binding that may be included in the B1s peak was evaluated by statistical analysis. Specifically, spectra corresponding to BO binding between 190 eV and 195 eV were considered statistically significant if the difference between the maximum and minimum intensity in the 190 eV to 195 eV range was greater than three times the standard deviation σ in the 197 eV to 203 eV range.

[0096] [Identification of BC bonds in silicone resins] Spectra corresponding to BC binding between 185 eV and 190 eV were considered virtually undetectable if the difference between the maximum and minimum intensities in the 185 eV to 190 eV range was less than or equal to twice the standard deviation σ in the 197 eV to 203 eV range.

[0097] <<Shrinkage evaluation after accelerated lightfastness test>> Using Metal Weather (Daipla Westin Co., Ltd., KW-R5TP-A), the silicone resin of Example 1, formed on a glass substrate, was subjected to an irradiance of 1200 [W / m²] under conditions of a back panel temperature of 63°C and humidity of 50%. 2 An accelerated lightfastness test (degradation acceleration test) was conducted under the conditions of 70 hours.

[0098] For the silicone resin before the accelerated lightfastness test (initial state), a portion of each silicone resin was scraped with a spatula, and the difference in height between the scraped and unscraped portions was measured using a Dektak (Bruker, Vecco Dektak 150). This difference in height was defined as the initial thickness of the silicone resin (T0). Similarly, the thickness of the silicone resin after the accelerated lightfastness test (T1) was measured. The shrinkage rate was calculated based on the following formula.

[0099] Shrinkage rate (%) = 100 × (T0 - T1) / T0

[0100] [Examples 2-3] As shown in Table 1, the curable compositions and silicone resins of Examples 2 and 3 were prepared and evaluated in the same manner as in Example 1, except that the parts by mass of the T-isomer silicone resin and boric acid compound in the curable composition were changed. The results are shown in Table 1.

[0101] [Example 4] As shown in Table 1, the curable composition of Example 4 was prepared in the same manner as in Example 1, except that the composition of the curable composition was changed. In addition, the drying and curing conditions for the silicone resin were changed from 100°C for 60 minutes to 150°C for 30 minutes, and the silicone resin of Example 4 was prepared and evaluated. The results are shown in Table 1.

[0102] [Table 1]

[0103] [Evaluation Results] The evaluation results for Examples 1 to 4 are shown in Table 1. From the results in Table 1, it was found that a curable composition containing a curable silicone and a specific boron compound, satisfying a specific Si / B ratio, can suppress shrinkage after the accelerated lightfastness test and form a silicone resin with excellent adhesion, lightfastness, heat resistance, and durability. On the other hand, it was found that the effect of suppressing shrinkage after the accelerated lightfastness test is inferior when the boron compound is not included.

[0104] The light-emitting device relating to this disclosure has been described above, but this disclosure is not limited to the embodiments described above. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope described in the claims. These also naturally fall within the technical scope of this disclosure.

[0105] The following additional information is disclosed regarding the above embodiments, etc. [Note 1] Curable silicone and A boron compound selected from the group consisting of boronic acid, boronic acid ester, boric acid, boric acid ester, and boroxine derivatives thereof, A curable composition containing, A curable composition in which the content ratio of silicon Si to boron B (Si / B) in the cured product obtained by heating the curable composition at 100°C for 60 minutes is greater than 10 and less than or equal to 60. [Note 2] The curable composition according to Appendix 1, wherein the boron compound is selected from the group consisting of boric acid, boric acid esters, and boroxine derivatives thereof. [Note 3] The curable composition according to Appendix 1 or 2, wherein the content ratio of silicon Si to boron B in the cured product of the curable composition (Si / B) is 15 or more and 35 or less. [Note 4] The aforementioned curable silicone is RSiO 3 / 2 A curable composition according to any one of the appendices 1 to 3, comprising an organosiloxy unit (T unit) represented by the formula (wherein R represents an organic group). [Note 5] A curable composition according to any one of the appendices 1 to 4, further comprising at least one metallic element selected from 3d transition metals, 4d transition metals, lanthanide metals, bismuth, aluminum, tin, and zinc. [Note 6] A curable composition according to any one of the following appendices, namely an ultraviolet light-emitting element, an exterior coating element, and a space equipment element. [Note 7] The silicon (Si) content ratio (Si / B) to boron (B) is greater than 10 and less than or equal to 60. A silicone resin in which, when the C1s peak top is set to 284.38 eV, a spectrum corresponding to a BO bond between 190 eV and 195 eV is detected in the spectrum obtained by X-ray electron spectroscopy (XPS). [Note 8] The silicone resin described in Appendix 7, wherein the spectrum corresponding to BC bonding in the range of 185 eV to 190 eV is virtually undetectable. [Note 9] A silicone resin as described in Appendix 7 or 8, wherein the content ratio of silicon (Si) to boron (B) (Si / B) is 15 or more and 35 or less. [Note 10] RSiO 3 / 2 A silicone resin according to any one of the appendices 7 to 9, comprising an organosiloxy unit (T unit) represented by the formula (wherein R represents an organic group). [Note 11] A silicone resin according to any one of Annexes 7 to 10, further comprising at least one metallic element selected from 3d transition metals, 4d transition metals, lanthanide metals, bismuth, aluminum, tin, and zinc. [Note 12] A silicone resin according to any one of the items in Appendix 7 to 11, which is an ultraviolet light-emitting element member, an exterior coating member, or a space equipment member. [Explanation of symbols]

[0106] 1. Ultraviolet light emission device 2 light-emitting elements 21 Light exit surface (first interface) 3. Lenses (optical glass components) 31 Opposing surface (second interface) 5 Adhesive layer

Claims

1. Curable silicone and A boron compound selected from the group consisting of boronic acid, boronic acid ester, boric acid, boric acid ester, and boroxine derivatives thereof, A curable composition containing, A curable composition in which the content ratio of silicon Si to boron B (Si / B) in the cured product obtained by heating the curable composition at 100°C for 60 minutes is greater than 10 and less than or equal to 60.

2. The curable composition according to claim 1, wherein the boron compound is selected from the group consisting of boric acid, boric acid esters, and boroxine derivatives thereof.

3. The curable composition according to claim 1, wherein the content ratio of silicon Si to boron B in the cured product of the curable composition (Si / B) is 15 or more and 35 or less.

4. The curable silicone is RSiO ３／２ The curable composition according to claim 1, comprising an organosiloxy unit (T unit) represented by the formula (wherein R represents an organic group).

5. The curable composition according to claim 1, further comprising at least one metallic element selected from 3d transition metals, 4d transition metals, lanthanide metals, bismuth, aluminum, tin, and zinc.

6. The curable composition according to claim 1, which is any of the ultraviolet light-emitting element member, the exterior coating member, and the space equipment member.

7. The silicon (Si) content ratio to boron (B) is greater than 10 and less than or equal to 60. A silicone resin in which, when the C1s peak top is set to 284.38 eV, a spectrum corresponding to a B-O bond between 190 eV and 195 eV is detected in the spectrum obtained by X-ray electron spectroscopy (XPS).

8. The silicone resin according to claim 7, wherein the spectrum corresponding to the B-C bond in the range of 185 eV to 190 eV is substantially undetectable.

9. The silicone resin according to claim 7, wherein the content ratio of silicon Si to boron B (Si / B) is 15 or more and 35 or less.

10. RSiO ３／２ The silicone resin according to claim 7, comprising an organosiloxy unit (T unit) represented by the formula (wherein R represents an organic group).

11. The silicone resin according to claim 7, further comprising at least one metallic element selected from 3d transition metals, 4d transition metals, lanthanide metals, bismuth, aluminum, tin, and zinc.

12. The silicone resin according to claim 7, which is any of the ultraviolet light-emitting element member, the exterior coating member, and the space equipment member.

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