JP7672136B2 - Ultraviolet light emitting element sealant and ultraviolet light emitting device having same - Google Patents

Description

The present invention relates to an ultraviolet light emitting element sealing material that has high transmittance even in the ultraviolet wavelength region and has excellent efficiency in extracting ultraviolet light from an ultraviolet light emitting element, and an ultraviolet light emitting device having the same.

In recent years, ultraviolet light has been utilized in a variety of fields. Ultraviolet LEDs (UV-LEDs) that emit various emission spectra including wavelengths in the ultraviolet range, particularly short-wavelength ultraviolet light, have been developed to directly utilize the high energy of ultraviolet light for sterilization and printing ink curing, or to be used in semiconductor light-emitting devices that use phosphors to convert the wavelength of the irradiated ultraviolet light and adjust the spectral characteristics.

Usually, ultraviolet rays are divided into three wavelength ranges: UVA (ultraviolet A rays: wavelength 400-315 nm), UVB (ultraviolet B rays: wavelength 315-280 nm), and UVC (ultraviolet C rays: wavelength 280-100 nm). Of the rays from the sun, the highly energetic UVC is absorbed by the ozone layer and does not reach the earth's surface, but UVA and UVB reach the earth's surface and are useful for activating vitamin D through sunbathing, sterilizing laundry and futons when drying, and photosynthesis, but are also known to cause sunburn, inflammation, age spots, wrinkles, and the development of skin cancer.

Taking advantage of these characteristics of ultraviolet light, artificial ultraviolet light is used for a variety of industrial and everyday purposes. For example, UVC wavelengths are used in the fields of sterilization, water purification, and air purification, UVB wavelengths are used in the medical and agricultural fields, and UVA wavelengths are used in the fields of resin hardening, adhesion, printing, and painting.

Traditionally, mercury-based ultraviolet lamps have been used as a source of ultraviolet light, but due to environmental concerns and power consumption, there is a shift to ultraviolet LEDs.

Compared to ultraviolet lamp light sources that irradiate multiple wavelengths, ultraviolet LEDs have a narrower emission wavelength range, and are highly power efficient at specific wavelengths, contributing to energy savings. They also have the advantages of being quick to light up, no degradation from switching the power on and off, easy to use due to their long life and low maintenance, compact, lightweight and flexible design, and environmentally friendly as they do not use mercury, but they also have the disadvantage of having a significantly lower output than ultraviolet lamps and a higher price per unit of light.

Conventional light-emitting devices using UV LEDs did not have a sealant that could protect the UV LED light-emitting element and transmit UV light, so they had a fundamental problem in that the extraction efficiency of the UV light emitted from the light-emitting element was reduced due to the difference in refractive index between the light-emitting element and the air layer, and internal reflection within the light-emitting element.

In view of this, Patent Document 1 discloses a curable resin composition for forming an encapsulating material having high light transmittance in the ultraviolet wavelength range, high ultraviolet resistance, and high heat resistance, which contains an alkoxy oligomer and a curing catalyst, in which the alkoxy oligomer has an organopolysiloxane structure and has one or more structural units selected from a structural unit represented by (R ¹ R ² R ³ SiO _1/2 ), a structural unit represented by (R ⁴ R ⁵ SiO _2/2 ), a structural unit represented by (R ⁶ SiO _3/2 ), and a structural unit represented by (SiO _4/2 ), and further contains a structural unit represented by (R ⁷ _a (OR ⁸ ) _3-a SiO _1/2 ), a structural unit represented by (R ⁹ _b (OR ¹⁰ ) _2-b SiO _2/2 ), and a structural unit represented by ((OR ¹¹ )SiO _3/2 When all siloxane units constituting the alkoxy oligomer are taken as 100 mol %, the alkoxy oligomer contains 90 to 100 mol % of these structural units, the atomic ratio of the total amount of O atoms to the total amount of Si atoms contained in the alkoxy oligomer is 2.3 to 3.5, and the curing catalyst is phosphoric acid or an alkoxide of a metal such as B or A.

Patent Document 2 discloses a semiconductor light-emitting device that includes a package substrate that houses a semiconductor light-emitting element that emits ultraviolet light with a wavelength of 360 nm or less, a thin film layer of a predetermined thickness formed on the package substrate, and a sealant that is provided on the thin film layer and is formed of silicone resin to have a lens-like shape and seals the semiconductor light-emitting element, the sealant being formed so that the contact angle with the thin film layer is 15 degrees or more.

JP 2016-186063 A JP 2020-174153 A

However, when the light transmittance of the encapsulant used in an ultraviolet LED device equipped with a semiconductor light-emitting element that emits ultraviolet light with a wavelength of 280 nm or less is insufficient, if the encapsulant has low light transmittance, the light extraction efficiency of the ultraviolet light from the semiconductor light-emitting element improves, but the encapsulant causes a loss of ultraviolet light, making it difficult to improve the output and radiant flux of the ultraviolet LED device itself.

The present invention has been made to solve the above problems, and aims to provide an ultraviolet light emitting element sealant that has higher ultraviolet light transmittance in the ultraviolet wavelength range, particularly in the UVC region, than conventionally, and has higher efficiency than conventionally in extracting ultraviolet light from an ultraviolet light emitting element, particularly ultraviolet light in the UVC region, and that also has excellent ultraviolet resistance and high heat resistance, and an ultraviolet light emitting device in which an ultraviolet light emitting element is sealed with the ultraviolet light emitting element sealant.

The ultraviolet light emitting device sealant made to achieve the above-mentioned object is an ultraviolet light emitting device sealant containing a condensation polymerization silicone resin for sealing an ultraviolet light emitting device, wherein the condensation polymerization silicone resin contains repeating units of monoorganosiloxy units, that is, M units, diorganosiloxy units, T units, triorganosiloxy units, and Q units, the T units being at least 90 mol % in terms of the molar ratio of the number of units to the total number of the monoorganosiloxy units , does not contain a curing catalyst, and has a Shore D hardness of 80 or more .

In this ultraviolet light emitting element sealing material, for example, the condensation polymerization silicone resin is any three-dimensional crosslinked silicone resin containing T units selected from the group consisting of T resins consisting of T units, MTQ resins having a combination of the M units, the T units, and the Q units, MDTQ resins having a combination of the M units, the D units, the T units, and the Q units, DT resins having a combination of the D units and the T units, and TDQ resins having a combination of the D units, the T units, and the Q units.

In this ultraviolet light emitting element sealing material, it is preferable that the condensation polymerization silicone resin has the repeating unit consisting only of the T unit.

In this ultraviolet light emitting element sealing material, for example, the condensation polymerization silicone resin is a condensation polymerization cured product obtained by condensation polymerization of a composition containing condensation polymerization silicone resin raw material components.

It is preferable that the condensation polymerization silicone resin raw material component of this ultraviolet light emitting element sealing material has at least a hydroxyl group at the terminal and undergoes the condensation polymerization via the hydroxyl group.

It is even more preferable that the ultraviolet light emitting element sealant is one in which the composition containing the condensation polymerization silicone resin raw material component is solid at room temperature, becomes fluid when heated to a temperature lower than the heat curing temperature at which the condensation polymerization occurs, and undergoes the condensation polymerization at a temperature equal to or higher than the heat curing temperature to become the condensation polymerization cured product.

This ultraviolet light emitting element sealing material may be configured to cover at least a portion of the light emitting surface of the ultraviolet light emitting element.

This ultraviolet light emitting device sealing material may cover at least a part of the light emitting surface of the ultraviolet light emitting device.

This ultraviolet light emitting device encapsulant may exhibit optical properties such that the average transmittance for wavelengths between 200 and 300 nm is 70% or more.

This ultraviolet light emitting element encapsulant may exhibit optical properties that provide a transmittance of at least 60% at at least any wavelength between 200 and 250 nm.

This ultraviolet light emitting device encapsulant may have a transmittance of at least 90% at wavelengths between 250 and 280 nm.

The ultraviolet light emitting device that has been made to solve the above problems has an ultraviolet light emitting element mounting base material on which the ultraviolet light emitting element is mounted and connected to wiring, and an ultraviolet light emitting element sealing material that covers at least a portion of the light emitting surface of the ultraviolet light emitting element.

This ultraviolet light emitting device has an ultraviolet light extraction rate, calculated as the amount of ultraviolet light emitted from the ultraviolet light emitting element sealant relative to the amount of ultraviolet light irradiated from the ultraviolet light emitting element, that is 5% or more higher than an ultraviolet light emitting device that does not have the ultraviolet light emitting element sealant.

In this ultraviolet light emitting device, it is preferable that the ultraviolet light emitting element sealant has at least one surface modification treatment surface selected from a corona treatment surface, a plasma treatment surface, an ultraviolet treatment surface, an ozone cleaning treatment surface, and a molecular adhesive treatment surface.

This ultraviolet light emitting device may be such that, for example, the ultraviolet light emitting element sealant is made of quartz glass, non-quartz glass, or transparent resin, and also serves as an adhesive for adhering to a molded optical substrate member selected from an optical cube molded optical member, a rectangular molded optical member, a spherical molded optical member, a hemispherical molded optical member, a prism molded optical member, a spherical lens molded optical member, and an aspherical lens molded optical member.

This ultraviolet light emitting device may be such that at least any one of the bonding surfaces between the ultraviolet light emitting element sealant and the ultraviolet light emitting element and the ultraviolet light emitting element mounting substrate, and/or at least any one of the bonding surfaces between the ultraviolet light emitting element sealant and the molded optical substrate member has a surface modification treatment surface, such as a corona treatment surface, a plasma treatment surface, an ozone cleaning treatment surface, or a molecular adhesive treatment surface.
This ultraviolet light emitting device may be such that at least any one of the bonding surfaces between the ultraviolet light emitting element sealing material and the package molding member constituting the ultraviolet LED device, the ultraviolet light emitting element, and the ultraviolet light emitting element mounting substrate, and/or at least any one of the bonding surfaces between the ultraviolet light emitting element sealing material and the molded optical substrate member has a surface modification treatment surface such as a corona treatment surface, a plasma treatment surface, an ozone cleaning treatment surface, or a molecular adhesive treatment surface.

The ultraviolet light emitting element sealant of the present invention can seal ultraviolet light emitting elements, and by making the T unit the repeating unit of the condensation polymerization silicone resin 90 mol % or more, it can increase the ultraviolet light transmittance in the ultraviolet wavelength range of 400 to 100 nm, particularly in the UVC range of 280 to 100 nm, more than conventionally. As a result, this ultraviolet light emitting element sealant can increase the extraction efficiency of ultraviolet light, particularly ultraviolet light in the UVC range, from ultraviolet light emitting elements, more than conventional ultraviolet light emitting devices that do not have a sealant.

In addition, since the package molding material that constitutes the UV LED device is mainly made of ceramic or metal, there is a possibility that cracks will occur when the sealing material hardens due to differences in linear expansion coefficient with the sealing material, or that the sealing material will peel off from the package molding material. Therefore, by providing a resin buffer layer that has rubber elasticity and a linear expansion coefficient close to that of the UV light emitting element sealing material on areas other than the light emitting surface of the UV LED device, the resin buffer layer can flexibly respond to cracks that occur when the sealing material hardens due to differences in linear expansion coefficient or shrinkage rate with the package molding material, etc., and therefore cracks can be prevented.

This ultraviolet light emitting element encapsulant has moldability and an average transmittance of 70% or more, especially 80% or more, for the ultraviolet region of 200 to 300 nm wavelengths.

This ultraviolet light emitting element sealant transmits ultraviolet light with a wavelength of 200 to 300 nm from an ultraviolet light emitting element with high transmittance, while exhibiting excellent ultraviolet resistance over a long period of time without degradation even when exposed to highly active ultraviolet light irradiated from the ultraviolet light emitting element, and exhibiting high heat resistance over a long period of time without degradation due to heat generated by the ultraviolet light emitting element.

An ultraviolet light emitting device in which an ultraviolet light emitting element is sealed with this ultraviolet light emitting element sealant has higher ultraviolet light transmittance than conventional devices in the ultraviolet wavelength range, particularly in the UVC region, and has higher efficiency than conventional devices in extracting ultraviolet light from the ultraviolet light emitting element, particularly in the UVC region, as well as excellent ultraviolet resistance and high heat resistance.

1 is an exploded cross-sectional view showing a state in which an ultraviolet light emitting element sealing material according to the present invention is used, and an ultraviolet light emitting device using the same. FIG. 1 is a diagram showing an example of a combination of an ultraviolet light emitting element sealing material to which the present invention is applied and a molded optical substrate member. FIG. 2 is a schematic cross-sectional view showing another embodiment of an ultraviolet light emitting device using the ultraviolet light emitting element sealing material to which the present invention is applied. 1 is a graph showing the correlation between wavelength and transmittance in an evaluation of light transmittance of a molded sample of an ultraviolet light emitting element encapsulant to which the present invention is applied.

The following describes in detail the embodiments of the present invention, but the scope of the present invention is not limited to these embodiments.

The ultraviolet light emitting element sealant of the present invention is an optical component made of a condensation-polymerized silicone resin formed from a condensation-polymerized cured product obtained by condensation-polymerizing a composition containing condensation-polymerized silicone resin raw material components.

This ultraviolet light emitting device sealing material has as its base polymer such a condensation polymerization silicone resin which contains, as the total molar ratio, at least 90 mol % of T units out of the M units (M units: monofunctional units: _{R3SiO1 /2} ), D units (D units: difunctional units: _{R2SiO2 /2} units), T units (T units: trifunctional units: RSiO3 _/2 units), and Q units (Q units: tetrafunctional units: SiO4 _/2 ) (in each case, R specifically represents an alkyl group, such as a methyl group, or an aryl group, such as a phenyl group) shown in the chemical formula below, relative to the total molar ratio of all T, D, M, and Q units. This condensation-polymerized silicone resin may have at least any one of D units, M units, and Q units in addition to T units as repeating units. However, by using a condensation-polymerized silicone resin in which the main repeating units are composed of 90 mol % or more of T units, and preferably the repeating units are composed only of T structures, the ultraviolet light emitting device sealing material can have optical properties with a high transmittance of 70% or more for wavelengths of 200 to 300 nm.

More specifically, examples of the raw material components for the condensation polymerization silicone resin include polyorganosiloxanes (silicone resins) having Si-O-Si siloxane bonds in the main backbone, which is the main chain, as shown in the following chemical structural formula. In the following chemical structural formula, X is an organic functional group such as a monovalent unsubstituted or substituted hydrocarbon group that does not contain an aliphatic unsaturated group. Examples of X include hydroxyl groups; alkyl groups such as methyl, ethyl, propyl, pentyl, butyl, pentyl, and hexyl groups; aryl groups such as tolyl and xylyl groups; and substituted hydrocarbon groups such as chloromethyl, 3-chloropropyl, and 3-trifluoropropyl groups. In this case, when X is an organic functional group having a conjugated bond of C=C such as a phenyl group, it is preferable to remove the phenyl group in order to reduce the transmittance in the ultraviolet region. X may be one type or multiple types. In addition, it is preferable that most or all of X are methyl groups. O-R represents an alkoxysilyl group.

（式中、－Ｏ－Ｒはアルコキシシリル基、－Ｘはメチル基等の有機官能基を示す）

(In the formula, -O-R represents an alkoxysilyl group, and -X represents an organic functional group such as a methyl group.)

If the condensation polymerization silicone resin has 90 mol% or more of a T unit repeating structure, it may be a resin mainly composed of a T unit-containing three-dimensional crosslinked silicone resin selected from T resin consisting of only T units, MTQ resin having a combination of M units, T units, and Q units, MDTQ resin having a combination of M units, D units, T units, and Q units, DT resin having a combination of D units, T units, and TDQ resin having a combination of D units, T units, and Q units, or it may contain a condensation polymerization silicone resin having no T unit repeating structure and having at least one of M units, T units, and Q units as a minor component without T resin.

In the absence of a sealant, the UV light extraction rate would decrease due to the difference in refractive index between the UV light emitting element and the air layer and internal reflection, but this UV light emitting element sealant, which is made of a base resin that is a condensation polymerization silicone resin containing 90 mol % or more of T units, exists to cover the light emitting surface of the UV light emitting element, and by reducing the difference in refractive index between the UV light emitting element and the air layer, not only does it improve the extraction rate by 5% or more compared to an UV light emitting device without a UV light emitting element sealant, but it also has excellent moldability because it is formed from a composition containing condensation polymerization silicone resin raw material components.

On the other hand, ultraviolet light emitting element encapsulants made of condensation polymerization silicone resins with less than 90 mol% T units have an average transmittance of 70% or less for wavelengths of 200 to 300 nm, making it difficult to improve the output or radiant flux of the ultraviolet LED device itself, and causing degradation due to ultraviolet light.

Generally, silicone rubber or silicone resin has low transmittance in the ultraviolet region (especially UV-B and UV-C), and has not been used as an optical component such as an ultraviolet light emitting element sealant. However, the ultraviolet light emitting element sealant of the present invention uses a condensation polymerization silicone resin having 90 mol% or more of T units, and thus has high ultraviolet light transmittance in the ultraviolet wavelength region, especially in the UVC region, high ultraviolet light extraction efficiency, and excellent ultraviolet resistance and high heat resistance. On the other hand, an ultraviolet light emitting element sealant made of a condensation polymerization silicone resin consisting of only Q structures is close to a so-called glass structure, and while it has strong mechanical strength, it is difficult to mold it like a resin. In addition, MQ resin formed from M units and Q units is very strong and has good mechanical strength, but the film is brittle, making it difficult to form a three-dimensional shape, let alone a free-standing film, whereas T resin, MTQ resin, MDTQ resin, DT resin, TQ resin, and TDQ resin can be formed into a three-dimensional shape compared to MQ resin, and also has the strength derived from resin.

The ultraviolet light emitting element encapsulant is made of a cured silicone resin, which is a condensation polymerization silicone resin, as a base material, has a branched structure (T unit) of 90 mol% or more, and has a Shore D hardness of 40 to 95, preferably 45 to 90, and more preferably 50 to 85 after curing, thereby exhibiting the above-mentioned specific optical characteristics.

The ratio of T units in the condensation polymerization silicone resin of the ultraviolet light emitting device encapsulant is not particularly limited as long as it is 90 mol % or more, but is preferably 90% to 100%, more preferably 95% to 100%, and even more preferably 97% to 100%.

In particular, when the condensation polymerization silicone resin of the ultraviolet light emitting element sealant is molded using a condensation polymerization silicone resin with a high ratio of T units, such as 90 mol % or more of T units, it can achieve both high transmittance in the ultraviolet range and moldability compared to optical components molded with other silicone rubbers or silicone resins, such as addition polymerization silicone resins or addition polymerization silicone rubbers, or radical polymerization silicone resins or radical polymerization silicone rubbers. Thus, one of the factors that causes the ultraviolet light emitting element sealant to exhibit the above-mentioned specific optical properties is that the condensation polymerization silicone resin of the ultraviolet light emitting element sealant has a structure of T units as its main structure.

The condensation-polymerized silicone resin of the ultraviolet light emitting element sealant is formed by dehydrating the hydroxyl groups at one or both ends of the condensation-polymerized silicone resin raw material component, preferably at both ends, and hardening the resin into a condensation-polymerized silicone resin.

The mass average molecular weight of the condensation-polymerized silicone resin used in the ultraviolet light emitting device encapsulant is not particularly limited and may be appropriately selected depending on the intended use. For example, the mass average molecular weight of the condensation-polymerized silicone resin is preferably 2,000 to 7,000, more preferably 2,500 to 6,000, and even more preferably 3,000 to 5,000.

Condensation polymerization silicone resin raw material components that form the condensation polymerization silicone resin of the ultraviolet light emitting device sealant include YR3370, a condensation polymerization silicone resin manufactured by Momentive Performance Materials Japan, LLC, and KR-200, KR-220LP, KR-242A, KR-255, and KR-282, condensation polymerization silicone resins manufactured by Shin-Etsu Chemical Co., Ltd. In particular, it is recommended to select a condensation polymerization silicone resin that does not contain organic solvents, has an active ingredient content of 90% or more, and has a low volatile ingredient content of 10% or less.

The condensation polymerization silicone resin of the ultraviolet light emitting element sealant is a composition containing condensation polymerization silicone resin raw material components that is a solid that does not exhibit fluidity at room temperature, and when heated below the heat-curing temperature at which condensation polymerization occurs, it becomes liquid and exhibits fluidity although it has some viscosity. When heated to the heat-curing temperature or higher, for example 150°C or higher, and condensation polymerization occurs, a condensation polymerization cured product is obtained.

In this ultraviolet light emitting device sealant, it is preferable that the composition containing the condensation polymerization silicone resin raw material component does not contain organic and/or inorganic catalysts, such as metal catalysts such as platinum-containing catalysts, lead-containing catalysts, titanium-containing catalysts, aluminum-containing catalysts, zinc-based catalysts, and iron-based catalysts, phosphoric acid catalysts, amine-based catalysts, and in particular curing catalysts made of organic compounds. Since the composition containing the condensation polymerization silicone resin raw material component does not contain a catalyst, the ultraviolet light emitting device sealant also does not contain a catalyst, and as a result, the ultraviolet light emitting device sealant can reduce or eliminate the factors that cause the curing catalyst to absorb ultraviolet light, thereby increasing the average transmittance of ultraviolet light with a wavelength of 200 to 300 nm.

The composition containing the condensation-polymerized silicone resin raw material component used to form the ultraviolet light emitting device sealant preferably contains a condensation-polymerizable silicone resin raw material component that can be condensed and cured, from the viewpoint of eliminating factors that absorb ultraviolet light, such as C-C bonds and C=C bonds, as seen in the structural formula of addition-polymerized silicone.

It is preferable that such an ultraviolet emitting element sealant made of a condensation polymerization silicone resin has a corona irradiation treatment surface, a plasma irradiation treatment surface, or an ultraviolet ray irradiation treatment surface. As a result, organic functional groups that become Si-C bonds, such as some alkyl groups or phenyl groups, bonded to T units are eliminated by energy irradiation treatment or the like, resulting in a Q structure and/or a glass structure (Si=O structure or Si-OH structure). As a result, it is presumed that the Si group becomes inorganic, and by modifying, removing, or reducing the Si-C bonds, etc., which are considered to be factors that absorb wavelengths in the ultraviolet ray region, a high transmittance can be achieved even in the ultraviolet ray region. As a result, it is possible to obtain an ultraviolet emitting element sealant with stable characteristics, maintaining a high transmittance in the ultraviolet ray region while maintaining the transmittance in the visible region. Thus, one of the factors that causes the ultraviolet emitting element sealant to exhibit the above-mentioned specific optical characteristics is that the ultraviolet emitting element sealant is preferably made of a condensation polymerization silicone resin that does not have an addition-polymerizable functional group such as a vinyl group.

This ultraviolet light emitting element sealing material may be configured to cover at least a portion of the light emitting surface of the ultraviolet light emitting element.

The ultraviolet light emitting element sealant may have a Shore D hardness of 40 to 95, preferably 45 to 90, and more preferably 50 to 85 after curing.

The linear expansion coefficient of the condensation polymerization silicone resin used in the ultraviolet light emitting device sealing material may be 100 to 500, preferably 100 to 400, and more preferably 100 to 300.

The refractive index of the condensation polymerization silicone resin used in the ultraviolet light emitting device sealant at wavelengths of 300 nm or less in the ultraviolet region is 1.30 to 1.60, preferably 1.40 to 1.50, which improves the reduction in the ultraviolet light extraction efficiency caused by internal reflections and the like that occur due to the difference in refractive index between the ultraviolet light emitting device's refractive index at wavelengths of 300 nm or less in the ultraviolet region (1.70 to 2.00) and the air's refractive index at wavelengths of 300 nm or less in the ultraviolet region (0.90 to 1.10).

This ultraviolet light emitting element encapsulant may be a condensation polymerization silicone resin with a high ratio of T units, such as 90 mol % or more of T units, and thus exhibit optical properties such as an average transmittance of 70% or more, more preferably 80% or more, at wavelengths of 200 to 300 nm.

This ultraviolet light emitting element encapsulant may be a condensation polymerization silicone resin with a high ratio of T units, such as 90 mol % or more of T units, and thus exhibit optical properties such that the transmittance at least at any wavelength between 200 and 250 nm is at least 60%, more preferably 65%, and even more preferably 70%.

This ultraviolet light emitting element encapsulant may be a condensation polymerization silicone resin with a high ratio of T units, such as 90 mol % or more of T units, so that the transmittance is at least 90% at wavelengths between 250 and 280 nm.

As shown in FIG. 1, this ultraviolet light emitting device 1 is, for example, an ultraviolet light emitting element 13, which is a light emitting diode, and is connected to wiring patterns 15a and 15b, which are copper foil, via wiring 14a and 14b, to form an ultraviolet light emitting element mounting base material 20 made of insulating reflector 17a and substrate 16, a package case made of reflector 17b surrounding the ultraviolet light emitting element 13 in a recess 11, and a package molding member 10 made of reflector 12, for example, a metal film and ceramic, and an ultraviolet light emitting element sealing material 18 that seals the recess 11 together with the ultraviolet light emitting element 13.

In this ultraviolet light emitting device 1, the ultraviolet light emitting element sealant 18 may be a condensation polymerization silicone resin with a high ratio of T units, such as 90 mol % or more of T units, so that it also serves as an adhesive to adhere to the ultraviolet light emitting element 13.

This ultraviolet light emitting device 1 has a configuration of ultraviolet light emitting element sealant 18, so that the ultraviolet light extraction rate, calculated as the amount of ultraviolet light emitted from the ultraviolet light emitting element sealant 18 to the outside relative to the amount of ultraviolet light irradiated from the ultraviolet light emitting element 13, is at least 5% higher, preferably 10% higher, and more preferably 15% higher, compared to an ultraviolet light emitting device that does not have an ultraviolet light emitting element sealant.

As shown in FIG. 1 and FIG. 2(a) to (d), this ultraviolet light emitting device 1 may be configured such that the ultraviolet light emitting element sealant 18 also serves as an adhesive for adhering to a molded optical substrate member 30 selected from an optical cube molded optical member, a rectangular molded optical member, a spherical molded optical member, a hemispherical molded optical member, a prism molded optical member, a spherical lens molded optical member, and an aspherical lens molded optical member, which is made of quartz glass, non-quartz glass, a transparent resin, or the same or a different resin as the condensation polymerization silicone resin.

The shape of the molded optical substrate member 30 of such an ultraviolet light emitting device 1 is not particularly limited. The molded optical substrate member 30 of the ultraviolet light emitting device 1 may be, for example, as shown in Figures 2(a) and (b), a lens, for example, a convex lens such as a biconvex lens, a plano-convex lens (see Figure 2(a)), or a convex meniscus lens; a concave lens such as a biconcave lens, a plano-concave lens, or a concave meniscus lens; an aspheric lens; a cylindrical lens (see Figure 2(b)); a toroidal lens; a Fresnel lens; a lens sheet in a sheet-like shape having such a shape; a lens array in which a large number of such lenses are arranged; a film; or a light guide plate. Note that the ultraviolet light emitting element, the ultraviolet light emitting element mounting substrate, etc. are omitted in the figures.

The ultraviolet light emitting device 1 is such that the ultraviolet light emitting element sealant 18 has been subjected to a surface modification treatment, such as corona treatment, plasma treatment, or molecular adhesive, or can be adhered to the ultraviolet light emitting element 13, the ultraviolet light emitting element mounting substrate 20, the package molding member 10, and the molded optical substrate member 30 used as needed, etc., by using an adhesive.

The ultraviolet light emitting device 1, because the molded optical substrate member 30 is a lens, can collect, diffuse, scatter, or guide the light from the ultraviolet light emitting element 13, improve the light extraction efficiency from the ultraviolet light emitting element 13 and/or the ultraviolet light emitting element sealant 18, and adjust the light intensity and light irradiation area at the irradiation destination. The light from the ultraviolet light emitting element 13 at this time has a peak wavelength of 100 to 360 nm, preferably 100 to 280 nm, and more preferably 250 to 280 nm.

The ultraviolet light emitting device 1 may also be one in which the ultraviolet light emitting element sealant 18 is covered with a molded optical substrate 30 made of the same or different resin as the condensation polymerization silicone resin or made of quartz glass, or the molded optical substrate 30 may be a hybrid lens covered with a coating or covering member made of various silicone resins, such as a coating layer or a matte coating layer, or a light-collecting or light-diffusing covering member.

In other words, the ultraviolet light emitting device 1 can be used in combination with a molded optical substrate 30 that uses a three-dimensional or plate-shaped member such as quartz glass, which has high transmittance even in the ultraviolet region, by bonding or laminating an optical member made of organic resin with an optical member made of quartz glass, coating quartz glass with an organic resin and molding it, or molecularly bonding an optical member made of organic resin with quartz glass.

As long as the ultraviolet light emitting device 1 satisfies the required transmittance, the ultraviolet light emitting element sealing material 18 may contain an organic or inorganic filler that has light diffusing properties, wavelength converting properties, or thermal conductivity, or may have a separate layer.

As shown in Figures 3 (1a) to (1e), the ultraviolet light-emitting device 1 may be configured to seal the entire ultraviolet light-emitting element 13 with an ultraviolet light-emitting element sealant 18, or may cover only the light-emitting surface of the ultraviolet light-emitting element 13.

Specifically, as shown in FIG. 3 (1a), the ultraviolet light emitting device 1 may not have a package molding member, and the entire ultraviolet light emitting element 13 on the ultraviolet light emitting element mounting substrate 20 may be sealed with an ultraviolet light emitting element sealing material 18.

Specifically, the ultraviolet light emitting device 1 may be configured such that only the light emitting surface of the ultraviolet light emitting element 13 arranged in the center of the package molded member 10 is covered with the ultraviolet light emitting element sealing material 18 on the ultraviolet light emitting element mounting substrate 20 as shown in FIG. 1b, or the upper end of the package molded member 10 may be covered with the molded optical substrate member 30, which is a quartz glass plate, as shown in FIG. 1c.

Alternatively, the ultraviolet light emitting device 1 may be configured to seal only the upper light emitting surface of the ultraviolet light emitting element 13 arranged in the center of the package molded member 10 on the ultraviolet light emitting element mounting substrate 20 with a lens-shaped ultraviolet light emitting element sealing material 18 on the light emitting surface of the ultraviolet light emitting element 13, as shown in FIG. 1d, or may be configured to cover the upper end of the package molded member 10 with a molded optical substrate member 30 that is a quartz glass plate, as shown in FIG. 1e.

Alternatively, the ultraviolet light emitting device 1 may be configured with a resin buffer layer 40 made of an organic resin that covers the ultraviolet light emitting element 13 except for its light emitting surface and is filled into the molded package material or molded separately, as shown in Figures 3(2a) to (2f).

Specifically, as shown in FIG. 3 (2a), the ultraviolet light emitting device 1 may be configured such that only the light emitting surface of the ultraviolet light emitting element 13 arranged in the center of the package molded member 10 on the ultraviolet light emitting element mounting substrate 20 is covered with a lens-shaped ultraviolet light emitting element sealant 18 of the same diameter, and the surrounding area of the ultraviolet light emitting element 13 at the same height is filled with a resin buffer layer 40, or as shown in FIG. 3 (2b), the entire light emitting surface of the ultraviolet light emitting element 13 and part of the resin buffer layer 40 may be covered with a wide range of ultraviolet light emitting element sealant 18.

Alternatively, as shown in FIG. 2c, the ultraviolet light emitting device 1 may be configured such that only the light emitting surface of the ultraviolet light emitting element 13 arranged in the center of the package molded member 10 on the ultraviolet light emitting element mounting substrate 20 is covered with a lens-shaped ultraviolet light emitting element sealing material 18 of the same diameter, and the ultraviolet light emitting element 13 and the ultraviolet light emitting element sealing material 18 are surrounded by a resin buffer layer 40 so that the convex lens shape is not buried.

Alternatively, as shown in FIG. 2d, the ultraviolet light emitting device 1 may be covered with a lens-shaped ultraviolet light emitting element sealant 18 that is wider and expands upward than the light emitting surface of the ultraviolet light emitting element 13 that is located in the center of the package molded member 10 on the ultraviolet light emitting element mounting substrate 20, and the ultraviolet light emitting element 13 and the ultraviolet light emitting element sealant 18 are filled with a resin buffer layer 40 so that they fit just inside.

Alternatively, as shown in FIG. 2e, the ultraviolet light emitting device 1 may be configured such that the ultraviolet light emitting element 13 arranged in the center of the package molded member 10 is surrounded by a resin buffer layer 40 of the same height on the ultraviolet light emitting element mounting substrate 20, and the ultraviolet light emitting element 13 and the resin buffer layer 40 are covered with a plate-shaped ultraviolet light emitting element sealing material 18 of the same diameter as the hollow space in the package molded member 10, so that the periphery and top surface of the ultraviolet light emitting element 13 are covered with the ultraviolet light emitting element sealing material 18, and the surroundings are filled with the resin buffer layer 40.

This resin buffer layer 40 has rubber elasticity and is made of a resin with a linear expansion coefficient close to that of the ultraviolet light emitting element sealant 18, which makes it possible to prevent cracks that occur when the sealant 18 hardens due to differences in the linear expansion coefficient or shrinkage rate of the package molding member 10, etc.

This resin buffer layer 40 may be a layer made of an organic resin, in which case, examples of the organic resin include low-hardness silicone resins. The hardness of the organic resin after curing is 10 to 80 Shore A, preferably 10 to 70, and more preferably 10 to 60, so that even if differences occur in the linear expansion coefficient or shrinkage rate of the package molding member 10, etc., it can follow and protect the ultraviolet light emitting element encapsulant 18.

The resin buffer layer 40 may be formed from a silicone resin, and such a silicone resin is preferably a silicone resin that is liquid before curing, such as LSR7010, LSR7020, LSR7030, LSR7040, LSR7050, LSR7060, LSR7070, LSR7080, and LSR7090 manufactured by Momentive Performance Materials Japan LLC, and MS-1001, MS-1002, and MS-1003 manufactured by Dow Toray Co., Ltd.

Metal fillers such as alumina, aluminum nitride, aluminum, silver, and titanium, and inorganic fillers such as titanium oxide and magnesium hydroxide may be added to the silicone resin that forms the resin buffer layer 40 in order to improve heat transfer and UV light reflection performance, and to provide UV protection to the light-emitting element.

Referring to FIG. 1, the ultraviolet light emitting device 1 is produced as follows. The ultraviolet light emitting device mounting substrate 20, which mounts the ultraviolet light emitting device 13, and connects it to the copper foil 15a and 15b, which are the wiring pattern, is joined with an adhesive to the package molding member 10, which is a package case surrounding the ultraviolet light emitting device 13 in the recess 11, and then the composition containing the condensation polymerization silicone resin raw material component is heated to a heat curing temperature or lower, for example, 100°C or lower, to make it fluid, and then the composition is filled into the recess, and then heated to a heat curing temperature, for example, 150°C, to form the ultraviolet light emitting device encapsulant 18 made of a cured product that has been cured into a condensation polymerization silicone resin. At this time, as shown in FIG. 2 and FIG. 3, the ultraviolet light emitting device 1 may be obtained by covering and adhering the ultraviolet light emitting device encapsulant 18 with a molded optical substrate 30 before or after curing as necessary, or a resin buffer layer 40 may be provided to obtain the ultraviolet light emitting device 1.

Below, we will explain examples in which the present invention is applied and comparative examples in which the present invention is not applied.

(Preparation of UV-light-emitting element encapsulant: Preparation of composition containing condensation-polymerized silicone resin raw material component)
As shown in Table 1 below, compositions containing condensation-polymerized silicone resin raw material components of Example 1 and Comparative Examples 1 to 3 were prepared.

Example 1
100 g of YR3370 (manufactured by Momentive Performance Materials Japan, LLC, product name: methyl-based silicone resin), which is solid at room temperature, was weighed out, transferred to a syringe, and placed in an oven set to 80° C., whereby the YR3370 was heated and melted into a flowable liquid.

(Comparative Example 1)
25 g of YR3370, which is a solid at room temperature, 75 g of X-40-9225 (manufactured by Shin-Etsu Chemical Co., Ltd., product name: condensation polymerization silicone resin mainly composed of T units), which is a liquid at room temperature for adding a curing catalyst, and 1 g of D-15 (manufactured by Shin-Etsu Chemical Co., Ltd., product name: zinc-based curing catalyst), which is a curing catalyst, were weighed out, stirred and uniformly dispersed, transferred to a syringe, and placed in an oven set to 80°C, where they were heated and melted into a flowable liquid.

(Comparative Example 2)
25 g of YR3370, which is a solid at room temperature, 75 g of X-40-9225 (manufactured by Shin-Etsu Chemical Co., Ltd., product name: condensation polymerization silicone resin mainly composed of T units), which is a liquid at room temperature for adding a curing catalyst, and 3 g of D-15 (manufactured by Shin-Etsu Chemical Co., Ltd., product name: zinc-based curing catalyst), which is a curing catalyst, were weighed out, stirred and uniformly dispersed, transferred to a syringe, and placed in an oven set at 80°C, where they were heated and melted into a flowable liquid.

(Comparative Example 3)
100 g of MS-1003 (product name: addition type silicone resin, manufactured by Dow Toray Industries, Inc.), which is liquid at room temperature, was weighed out and transferred into a syringe.

(Preparation of molded sample of ultraviolet light emitting device encapsulant and evaluation of its appearance)
The compositions containing the condensation polymerization silicone resin raw material components for the flowable ultraviolet light emitting element sealant of Example 1 and Comparative Examples 1 to 3 were poured into a mold and heated at 150°C or higher to prepare flat plate samples with a thickness of 1 mm, and the samples were evaluated for cracks, etc. Samples with no abnormalities in appearance were rated as pass (◯), and samples with abnormalities were rated as fail (×). The results are summarized in Table 2.

As is clear from Table 2, the samples derived from the compositions containing the condensation polymerization silicone resin raw material components in Example 1 and Comparative Example 3 had no abnormalities in appearance. The samples derived from the compositions containing the condensation polymerization silicone resin raw material components in Comparative Examples 1 and 2 had layer separation, were abnormal in appearance, and the upper resin layer was brittle.

(Preparation of molded sample of ultraviolet light emitting device encapsulant and evaluation of its light transmittance)
The compositions containing the condensation polymerization silicone resin raw material component for ultraviolet light emitting element sealing material having flowability of Example 1 and Comparative Examples 1 to 3 were poured into a mold, heated to 150°C, and flat plate samples with a thickness of 1 mm were prepared, and the light transmittance in the wavelength range of 200 to 500 nm was evaluated using a spectrophotometer UV-3600Plus (product name, manufactured by Shimadzu Corporation). The results are summarized in Figure 4.
Table 3 shows the details of the transmittance in each wavelength range of Example 1 and Comparative Example 3, which were free of any particular abnormality in appearance.

As is clear from Figure 4 and Table 3, the molded sample derived from the composition containing the condensation polymerization silicone resin raw material components of Example 1 exhibited high transmittance over the entire wavelength range from 200 to 500 nm, while the molded sample derived from the composition containing the condensation polymerization silicone resin raw material components of Comparative Examples 1 to 3 exhibited relatively low transmittance over the entire wavelength range from 200 to 500 nm, particularly low transmittance at 200 to 360 nm, and particularly low transmittance in the UVC wavelength range.

(Preparation of ultraviolet light emitting device and evaluation of its ultraviolet resistance and ultraviolet light emission intensity)
Example 2
An NCSU334B (manufactured by Nichia Corporation, product name: emission peak wavelength 280 nm) with the quartz glass window removed was prepared as an ultraviolet light-emitting device, and the condensation polymerization silicone resin raw material component-containing composition for flowable ultraviolet light-emitting device encapsulant of Example 1 and Comparative Example 3 was poured into the recess so as to cover the top surface which would become the light-emitting surface of the ultraviolet light-emitting device, and cured by heating at 150°C or higher to produce an ultraviolet light-emitting device having a cured ultraviolet light-emitting device encapsulant.

Example 3
In another embodiment, NCSU334B (manufactured by Nichia Corporation, product name: emission peak wavelength 280 nm) with the quartz glass window removed was prepared as an ultraviolet light-emitting device, and MS-1003 (manufactured by Dow-Toray Industries, Inc., product name: addition type silicone resin), which is liquid at room temperature, was poured into the depression so as not to cover the top surface which becomes the light-emitting surface of the ultraviolet light-emitting element, and then heated and cured at 150°C to form a resin buffer layer. After that, the flowable ultraviolet light-emitting element sealing material of Example 1 was poured into the top surface which becomes the light-emitting surface of the ultraviolet light-emitting element so as to cover it, and an ultraviolet light-emitting device having a resin buffer layer and cured ultraviolet light-emitting element sealing material was produced.

(UV resistance evaluation test and UV light emission intensity evaluation test)
To evaluate the emission intensity of ultraviolet light, an ultraviolet integrating light meter UIT-250 and a separate type receiver for ultraviolet integrating light meter UVD-S254 (both product names manufactured by Ushio Inc.) were used to measure the peak illuminance [P. mW/cm2] of the ultraviolet light emitted from the ultraviolet light emitting device.
A current value of 350 mA was passed through the NCSU334B with the quartz glass window removed to cause it to emit light, a separate type light receiver UVD-S254 was placed on the top surface of the ultraviolet light emitting device, and the peak illuminance was measured without any ultraviolet light emitting element sealant. Then, the peak illuminance was measured for the ultraviolet light emitting device having the cured ultraviolet light emitting element sealant of Example 2, and the ultraviolet light emitting device having the resin buffer layer and the cured ultraviolet light emitting element sealant of Example 3. The results are shown in Table 4.

As is clear from Table 4, the peak illuminance of the ultraviolet light emitting devices of Examples 2 and 3 having the ultraviolet light emitting element encapsulant is improved compared to the ultraviolet light emitting device without the ultraviolet light emitting element encapsulant, and no deterioration of the ultraviolet light emitting element encapsulant due to ultraviolet light irradiation when the ultraviolet light emitting device is turned on is observed. Furthermore, the ultraviolet light emitting devices having the resin buffer layer and the cured ultraviolet light emitting element encapsulant of Examples 2 and 3 can stably cure the ultraviolet light emitting element encapsulant, and no cracks or the like were observed due to heat generation caused by turning on the ultraviolet light emitting device.

The ultraviolet light emitting element sealant of the present invention can be used as an optical component in the fields of sterilization and disinfection, water purification, and air purification, which require high transmittance even in the ultraviolet wavelength region, especially in the deep ultraviolet region, and/or as a sealant in the optical field for collecting, diffusing, diffusing, or guiding ultraviolet wavelengths, especially in the deep ultraviolet region, and improving the light extraction efficiency of light emitting elements. In addition, it is possible to produce an ultraviolet light emitting element sealant that has good moldability, is inexpensive, and has high transmittance even in the ultraviolet region, like quartz glass.

1 is an ultraviolet light emitting device, 10 is a molded package member, 11 is a recess, 12 is a reflector, 13 is an ultraviolet light emitting element, 14a and 14b are wiring, 15a and 15b are wiring patterns, 16 is a substrate, 17a is an insulating reflector, 17b is a reflector, 18 is an ultraviolet light emitting element sealing material, 20 is an ultraviolet light emitting element mounting substrate, 30 is a molded optical substrate member, and 40 is a resin buffer layer.

Claims (16)

The ultraviolet light emitting device sealant contains a condensation polymerization silicone resin and is used to seal an ultraviolet light emitting device, the condensation polymerization silicone resin having repeating units of monoorganosiloxy units, namely M units, diorganosiloxy units, T units, triorganosiloxy units, and Q units, the T units being at least 90 mol % in terms of the molar ratio of the number of units to the total number of the monoorganosiloxy units , the ultraviolet light emitting device sealant being free of a curing catalyst, and having a Shore D hardness of 80 or more . The ultraviolet emitting element encapsulant according to claim 1, characterized in that the condensation polymerization silicone resin is any three-dimensional crosslinked silicone resin containing T units selected from the group consisting of a T resin consisting of the T units, an MTQ resin having a combination of the M units, the T units, and the Q units, an MDTQ resin having a combination of the M units, the D units, the T units, and the Q units, a DT resin having a combination of the D units and the T units, and a TDQ resin having a combination of the D units, the T units, and the Q units. The ultraviolet light emitting element encapsulant according to claim 1, characterized in that the condensation polymerization silicone resin has the repeating unit consisting only of the T unit. The ultraviolet emitting element encapsulant according to any one of claims 1 to 3, characterized in that the condensation polymerization silicone resin is a condensation polymerization cured product obtained by condensation polymerization of a composition containing condensation polymerization silicone resin raw material components. The ultraviolet emitting element encapsulant according to claim 4, characterized in that the condensation polymerization silicone resin raw material component has at least a hydroxyl group at the end and undergoes the condensation polymerization via the hydroxyl group. The ultraviolet light emitting element encapsulant according to claim 4, characterized in that the composition containing the condensation polymerization silicone resin raw material component is solid at room temperature, becomes fluid when heated to a temperature lower than the heat-curing temperature at which the condensation polymerization is performed, and undergoes the condensation polymerization at a temperature equal to or higher than the heat-curing temperature to become the condensation polymerization cured product. An ultraviolet light emitting element encapsulant according to any one of claims 1 to 6, characterized in that it is intended to cover at least a portion of the light emitting surface of an ultraviolet light emitting element. 8. The ultraviolet emitting element encapsulant according to claim 1, wherein the encapsulant covers at least a part of the light emitting surface of the ultraviolet emitting element. An ultraviolet light emitting element encapsulant according to any one of claims 1 to 8, characterized in that it exhibits optical properties such that the average transmittance at wavelengths of 200 to 300 nm is 70% or more. An ultraviolet light emitting element encapsulant according to any one of claims 1 to 9, characterized in that it exhibits optical properties that make the transmittance at least 60% at at least any wavelength between 200 and 250 nm. An ultraviolet light emitting element encapsulant according to any one of claims 1 to 10, characterized in that the transmittance is at least 90% at any wavelength between 250 and 280 nm. An ultraviolet light emitting device comprising an ultraviolet light emitting element mounting base material on which the ultraviolet light emitting element is mounted and connected to wiring, and an ultraviolet light emitting element sealing material according to any one of claims 1 to 11, which covers at least a portion of the light emitting surface of the ultraviolet light emitting element. The ultraviolet light emitting device according to claim 12, characterized in that the ultraviolet light extraction rate, calculated as the amount of ultraviolet light emitted from the ultraviolet light emitting element encapsulant relative to the amount of ultraviolet light irradiated from the ultraviolet light emitting element, is 5% or more higher than that of an ultraviolet light emitting device without the ultraviolet light emitting element encapsulant. The ultraviolet light emitting device according to any one of claims 12 to 13, characterized in that the ultraviolet light emitting element sealing material has at least one surface modification treatment surface selected from a corona treatment surface, a plasma treatment surface, an ultraviolet treatment surface, an ozone cleaning treatment surface, and a molecular adhesive treatment surface. The ultraviolet light emitting device according to any one of claims 12 to 14, characterized in that the ultraviolet light emitting element sealing material also serves as an adhesive for adhering to a molded optical base material member selected from an optical cube molded optical member, a rectangular parallelepiped molded optical member, a spherical molded optical member, a hemispherical molded optical member, a prism molded optical member, a spherical lens molded optical member, and an aspherical lens molded optical member, which is made of quartz glass, non-quartz glass, or a transparent resin. The ultraviolet light-emitting device described in claim 15 , characterized in that at least one of the bonding surfaces between the ultraviolet light-emitting element sealing material and the ultraviolet light-emitting element and the ultraviolet light-emitting element mounting substrate, and/or at least one of the bonding surfaces between the ultraviolet light-emitting element sealing material and the molded optical substrate member has at least one surface modification treatment surface selected from a corona treatment surface, a plasma treatment surface, an ozone cleaning treatment surface, and a molecular adhesive treatment surface.

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