Optical member, and optical member for ultraviolet LED

Abstract

[Problem] The objective of the present invention is to provide an optical member which has excellent ultraviolet transmittance and in which a decrease in ultraviolet transmittance is suppressed even when exposed to a high-temperature, high-humidity environment for a long period of time, and in particular, to provide an optical member for an ultraviolet LED. [Solution] Provided is an optical member comprising a cured product of a condensation-curable organopolysiloxane represented by the following formula (1), (1): (R1 3SiO1 / 2)a(R2 2SiO2 / 2)b(R3SiO3 / 2)c(R4O1 / 2)d(HO1 / 2)e (in the formula, R1, R2, and R3 are each independently a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms, R4 is a monovalent saturated hydrocarbon group having 1 to 4 carbon atoms, a, b, and c are numbers satisfying a>0, 0.15<b≤0.30, c>0, and a+b+c= 1, d is a number satisfying 0≤d / (a+2b+3c)≤ 0.1, and e is a number satisfying 0<e). The cured product having a thickness of 4 mm has a transmittance of 90% or more for at least one light beam having a wavelength in the range of 260-280 nm at 25 °C, and after the cured product having a thickness of 4 mm is held for 1,000 hours in an environment of a temperature of 85 °C and a relative humidity of 85% RH, the cured product has a transmittance of 70% or more for at least one light beam having a wavelength in the range of 260-280 nm at 25 °C.

Description

Optical member, and optical member for ultraviolet LED

[0001] One aspect of the present invention relates to an optical member, and more particularly to an optical member for ultraviolet LEDs.

[0002] In recent years, ultraviolet rays have been utilized in various fields, and in particular, ultraviolet LEDs (UV-LEDs) that emit short-wavelength ultraviolet rays have been developed.

[0003] In general, ultraviolet rays are broadly classified by their wavelength range into UVA (ultraviolet A wave: wavelength 400 to 315 nm), UVB (ultraviolet B wave: wavelength 315 to 280 nm), and UVC (ultraviolet C wave: wavelength 280 to 100 nm), all of which are contained in sunlight. Among them, high-energy UVC is absorbed by the ozone layer and does not reach the ground surface. On the other hand, since low-energy UVA and UVB reach the ground surface, they bring useful effects to animals and plants such as activation of vitamin D through sunbathing, sterilization during laundry drying, and photosynthesis, but when exposed to excessive amounts of these rays, they are known to have adverse effects such as sunburn, inflammation, spots, wrinkles, and the onset of skin cancer.

[0004] Utilizing the high energy characteristics of such ultraviolet rays, artificial ultraviolet rays are used for various industrial and daily applications. For example, UVC wavelengths are used in the fields of disinfection and sterilization, water purification and air cleaning, UVB wavelengths are used in the fields of medicine and agriculture, and UVA wavelengths are used in fields such as resin curing, adhesion, printing, and coating.

[0005] Conventionally, ultraviolet lamps using mercury have been used as light sources for these ultraviolet rays, but the switch to ultraviolet LEDs is progressing due to environmental issues, power consumption and other factors.

[0006] Compared with ultraviolet lamp light sources that emit multiple wavelengths, ultraviolet LEDs have a narrow emission wavelength width, high power efficiency at specific wavelengths, and can contribute to energy saving. In addition, they have a fast lighting speed, no deterioration caused by power ON / OFF switching, and are excellent in usability due to their long service life and high maintainability. Furthermore, they are expected to be smaller, lighter, and have an improved degree of design freedom, and have the advantage of low environmental impact because they do not use mercury. On the other hand, there has been a problem that their output is significantly lower than that of mercury ultraviolet lamps, and the price per light quantity is high.

[0007] Accordingly, in order to stably improve the light extraction efficiency of LED devices and LED elements, Patent Document 1 proposes a light-emitting device comprising: a mounting substrate; a light-emitting element disposed on the mounting substrate and configured to emit ultraviolet light; a frame-shaped spacer disposed on the mounting substrate and surrounding the light-emitting element; a cover disposed on the spacer so as to cover the light-emitting element and configured to transmit the ultraviolet light emitted from the light-emitting element; and a lens made of synthetic quartz or the like disposed between the light-emitting element and the cover, wherein the lens faces the light-emitting element only across a space in the thickness direction of the mounting substrate, and the spacer has a positioning structure that positions the lens in the thickness direction and in a plane orthogonal to the thickness direction.

[0008] Further, Patent Document 2 proposes a light-emitting device having: a light source that emits deep ultraviolet light; and a light flux control member formed of a material having a property of increasing the transmittance of the deep ultraviolet light when irradiated with the deep ultraviolet light, and configured to control the light distribution of the deep ultraviolet light.

[0009] In ultraviolet LED devices, as in Patent Document 1, optical members are mainly formed of inorganic materials such as synthetic quartz which have high transmittance in the ultraviolet region, but their manufacturing methods are difficult, the degree of design freedom is low, and the optical members become expensive.

[0010] Further, in the light-emitting device having a light flux control member formed of a material having a property of increasing the transmittance of deep ultraviolet light as in Patent Document 2, there is a problem that characteristics such as the transmittance initially set by a designer change as the device is used.

[0011] Further, Patent Documents 3 and 4 propose optical members made of silicone resin having good light transmittance at a wavelength of 200 to 300 nm. However, such optical members have a problem that when used for a long time in a high-temperature and high-humidity environment, cracks occur inside the members, resulting in a decrease in light transmittance.

[0012] JP 2019-207956 A, JP 2020-9858 A, WO 2013 / 081794, WO 2022 / 075048

[0013] The present invention has been made to solve the above-described problems, and an object thereof is to provide an optical member that is excellent in ultraviolet transmittance and suppresses a decrease in ultraviolet transmittance even when exposed to a high-temperature high-humidity environment for a long time, and in particular, to provide an optical member for ultraviolet LEDs.

[0014] As a result of intensive studies to solve the above problems, the present inventors have found that a cured product of a condensation-curable polyorganosiloxane having a specific structure shown below gives an optical member that is excellent in ultraviolet transmittance and suppresses a decrease in ultraviolet transmittance even when exposed to a high-temperature high-humidity environment for a long time, and has completed the present invention.

[0015] That is, the present invention provides the following optical member. [1] The following formula (1) (R １ ３ SiO １／２ ) ａ (R ２ ２ SiO ２／２ ) ｂ (R ３ SiO ３／２ ) ｃ (R ４ O １／２ ) ｄ (HO １／２ ) ｅ (1) (wherein, R １ , R ２ and R ３ are each independently a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms, and R ４An optical component comprising a cured product of a condensation-curing organopolysiloxane represented by (where is a monovalent saturated hydrocarbon group having 1 to 4 carbon atoms, a, b, and c are numbers satisfying a > 0, 0.15 < b ≤ 0.30, c > 0, and a + b + c = 1, d is a number satisfying 0 ≤ d / (a ​​+ 2b + 3c) ≤ 0.1, and e is a number satisfying 0 < e), wherein the cured product of the 4 mm thick product has a transmittance of 90% or more of at least one light in the wavelength range of 260 to 280 nm at 25°C, and the transmittance of at least one light in the wavelength range of 260 to 280 nm at 25°C measured after leaving the 4 mm thick product in an environment of 85°C and 85% RH relative humidity for 1000 hours is 70% or more.

[0016] Furthermore, the present invention provides the following optical members and optical members for ultraviolet LEDs. [2] The optical member according to [1], wherein the condensation-curable organopolysiloxane has hydroxyl groups in an amount of 1.0 to 5.0% by mass relative to the mass of the condensation-curable organopolysiloxane. [3] The optical member according to [1] or [2], wherein the condensation-curable organopolysiloxane has a weight-average molecular weight of 10,000 to 30,000. [4] The optical member according to any one of [1] to [3], wherein in formula (1), a is a number between 0.10 and 0.30, b is a number between 0.15 and 0.30, c is a number between 0.50 and 0.82, and a + b + c = 1. [5] The optical member according to any one of [1] to [4] above, wherein the cured product having a thickness of 4 mm has an average transmittance of 90% or more for light at wavelengths of 260 nm, 265 nm, 270 nm, 275 nm and 280 nm at 25°C, and the average transmittance of the cured product having a thickness of 4 mm, measured for 1000 hours in an environment of 85°C and 85% RH at 25°C, for light at wavelengths of 260 nm, 265 nm, 270 nm, 275 nm and 280 nm at 25°C is 70% or more. [6] The optical member according to any one of [1] to [5] above, wherein the cured product is a cured product of a curable composition containing a condensation-curing type organopolysiloxane and a curing catalyst. [7] The optical member according to any one of [1] to [6] above, which is an optical member for ultraviolet LEDs. [8] The optical member for ultraviolet LEDs according to [7] above, which further comprises an optical substrate. [9] The optical component for ultraviolet LED according to [8] above, wherein the optical substrate is a quartz glass substrate.

[0017] The optical component of the present invention exhibits excellent ultraviolet transmittance and suppresses the decrease in ultraviolet transmittance even when exposed to high temperature and high humidity environments for extended periods, thus providing superior reliability. The optical component of the present invention can transmit light in the wavelength range of 260 to 280 nm with high transmittance while focusing, scattering, diffusing, or guiding light, making it suitable as an optical component for ultraviolet LEDs, such as lenses, lens sheets, lens arrays, films, and light guide plates. Furthermore, the optical component for ultraviolet LEDs of the present invention can also be used as a coating or covering member that covers an optical substrate molded from quartz glass or the like.

[0018] Figures 1(a) to (f) are schematic diagrams showing the usage of optical components.

[0019] The present invention will be described in more detail below. An optical member in one aspect of the present invention comprises a cured product of a condensation-curing organopolysiloxane represented by the following formula (1), (R １ ３ SiO １／２ ) ａ (R ２ ２ SiO ２／２ ) ｂ (R ３ SiO ３／２ ) ｃ (R ４ O １／２ ) ｄ (HO １／２ ) ｅ (1) (wherein, R １ , R ２ and R ３ Each of these is independently a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms, and R ４ (where a is a monovalent saturated hydrocarbon group having 1 to 4 carbon atoms, a, b and c are numbers satisfying a > 0, 0.15 < b ≤ 0.30, c > 0, and a + b + c = 1, d is a number satisfying 0 ≤ d / (a ​​+ 2b + 3c) ≤ 0.1, and e is a number satisfying 0 < e) The cured product having a thickness of 4 mm has a transmittance of 90% or more of at least one light in the wavelength range of 260 to 280 nm at 25°C, and the cured product having a thickness of 4 mm has a transmittance of 70% or more of at least one light in the wavelength range of 260 to 280 nm at 25°C, measured after the cured product has been left in an environment of 85°C and 85% RH relative humidity for 1000 hours.

[0020] R in equation (1) above １ , R ２ and R ３Each of these is independently a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms. Examples of monovalent saturated hydrocarbon groups include methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, t-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylpropyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, n-hexyl, and cyclohexyl groups. Preferably, it is a methyl group or an ethyl group, and more preferably a methyl group.

[0021] R ４ This is a monovalent saturated hydrocarbon group having 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, and t-butyl groups. Preferably, it is a methyl group or an ethyl group.

[0022] In the above formula (1), a, b, and c are numbers that satisfy a > 0, 0.15 < b ≤ 0.30, c > 0, and a + b + c = 1. Preferably, a is a number between 0.10 and 0.30, and more preferably between 0.15 and 0.25. If a is 0.10 or more, it is preferable because it can effectively suppress crack generation during heat curing. Also, if a is 0.30 or less, it is preferable because the organopolysiloxane has superior curability. b is a number greater than 0.15 and less than or equal to 0.30. Preferably, b is a number between 0.18 and 0.25. If b is 0.15 or less, the resulting cured product will not have sufficient stress relaxation and will crack in a high-temperature, high-humidity environment. If b exceeds 0.30, the strength of the resulting molded product will be insufficient and cracks will occur during demolding. c is preferably a number between 0.50 and less than 0.82, and more preferably between 0.60 and 0.70. If c is greater than or equal to the lower limit, the strength of the resulting molded product is improved, which is preferable. If it is less than the upper limit, the occurrence of cracks in high-temperature and high-humidity environments can be suppressed more effectively, which is also preferable.

[0023] The condensation-curing organopolysiloxane of the present invention is M unit (R １ ３ SiO １／２ ), D unit (R ２ ２ SiO ２／２ ), and T units (R３ SiO ３／２ The present invention is characterized by having (SiO₂) as an essential component, and the ratio of the number of D units to the total number of M units, D units, and T units (b / (a+b+c)) being greater than 0.15 and less than or equal to 0.30, preferably between 0.18 and 0.25. Because the ratio of the number of D units to the total number of M units, T units, and D units is within the above range, the resulting cured organopolysiloxane has high transmittance to light with a wavelength of 260 to 280 nm at 25°C, and can suppress the decrease in the above transmittance even when exposed to a high temperature and high humidity environment for a long time. Furthermore, it can suppress the occurrence of cracks inside the cured product in a high temperature and high humidity environment, and the occurrence of cracks during the molding of optical components. Preferably, the condensation-curing type organopolysiloxane of the present invention is (SiO₂ ４／２ It does not include the Q unit, which is expressed in units of ).

[0024] d is a number that satisfies 0 < d / (a+2b+3c) ≤ 0.1. From the viewpoint of reducing alcoholic volatile components during heat curing, d / (a+2b+3c) ≤ 0.05 is preferred.

[0025] e is a number satisfying 0 < e. This means that the organopolysiloxane contains hydroxyl groups (silanol groups). From the viewpoint of condensation curability, the amount of hydroxyl groups contained in the organopolysiloxane is preferably 1.0% to 5.0% by mass, and more preferably 1.0% to 3.0% by mass, relative to the mass of the organopolysiloxane. The amount of hydroxyl groups can be measured by the Grignard method, which quantifies the amount of methane generated using methylmagnesium iodide.

[0026] The weight-average molecular weight (Mw) of the above organopolysiloxane in gel permeation chromatography (GPC), calculated on a polystyrene basis, is preferably 7,000 to 50,000, and more preferably 10,000 to 30,000. If the weight-average molecular weight is above the lower limit, it exhibits excellent crack resistance during condensation curing, and if it is below the upper limit, the viscosity is lower, resulting in excellent handling of the polysiloxane before curing.

[0027] Furthermore, the above organopolysiloxanes may be used individually or in combination of two or more.

[0028] The above organopolysiloxane can be produced by known methods. For example, it can be obtained by hydrolyzing and condensing an alkoxysilane or a partially hydrolyzed condensate thereof, which can form siloxane units constituting the organopolysiloxane represented by formula (1) above by hydrolysis and condensation, in an organic solvent in which the starting silane compound and the resulting organopolysiloxane can be dissolved as needed, in the presence of an acid catalyst. The desired organopolysiloxane can be obtained by adjusting the mixing ratio of the starting silane compounds, the mixing timing, the reaction temperature and time, and the amounts of water and organic solvent used.

[0029] Examples of raw material silane compounds include trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, and hydrolysis condensates thereof.

[0030] The acid catalyst is not particularly limited as long as it has sufficient acidity to hydrolyze the alkoxysilyl group and dehydrate and condense the resulting silanol to form a siloxane bond. Furthermore, the acid catalyst may be in liquid, solid, or gaseous form and is not particularly limited in form. Examples of acid catalysts include hydrochloric acid, sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, acetic acid, and cationic ion exchange resins.

[0031] The hydrolysis condensation reaction can be carried out without a solvent, but organic solvents such as methanol, ethanol, isopropyl alcohol, butanol, diacetone alcohol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, acetone, toluene, and xylene may be used. When using an organic solvent, the amount is not particularly limited, but it is preferably 20 parts by mass or less, more preferably 0.25 to 10 parts by mass, and even more preferably 0.5 to 5 parts by mass, per 1 part by mass of the total of the raw material silane compound and siloxane.

[0032] The amount of water used in the reaction is preferably 0.4 to 1.5 moles, and more preferably 0.6 to 1.3 moles, per mole of alkoxysilyl groups contained in the reaction system.

[0033] The reaction temperature is not particularly limited, but is usually 0 to 150°C, preferably 20 to 120°C, more preferably 40 to 100°C, and even more preferably 50 to 80°C. The reaction time is usually 1 hour or more, preferably 2 to 72 hours.

[0034] It is preferable to remove the alcohol produced as a by-product of the hydrolysis condensation reaction of the alkoxysilyl group, unreacted raw materials, and low molecular weight siloxane by distillation. The temperature and pressure for this operation are not particularly limited as long as the conditions are such that these impurities can be removed, but are usually 10 to 150°C, preferably 60 to 120°C, and can be carried out under atmospheric pressure or reduced pressure.

[0035] In one embodiment of the present invention, the optical member includes a cured product of a curable composition containing an organopolysiloxane represented by formula (1) and a curing catalyst.

[0036] The curing catalyst is not particularly limited as long as it is used for curing general condensation-curing compositions. For example, alkyl tin compounds such as dibutyltin oxide and dioctyl tin oxide; alkyl tin ester compounds such as dibutyltin diacetate, dibutyltin dilaurate, dioctyl tin dilaurate, dibutyltin dioctoate, dioctyl tin dioctoate, and dioctyl tin diversate; tetraisopropoxytitanium, tetra-n-butoxytitanium, tetrakis(2-ethylhexoxy)titanium, tetra-t-butoxytitanium, dipropoxybis(acetylacetonate)titanium, titanium diisopropoxybis(ethylacetate) Titanate esters such as titanium isopropoxyoctylene glycol, titanium chelate compounds and their partial hydrolysates; zinc naphthenate, zinc stearate, zinc-2-ethyl octoate, iron-2-ethylhexoate, cobalt-2-ethylhexoate, manganese-2-ethylhexoate, cobalt naphthenate, aluminum acetylacetone, aluminum bis(ethylacetate) monon-normal butyrate, aluminum ethylacetate din-normal butyrate, A Aluminum compounds such as luminium tris(ethylacetacetate) and their hydrolysates; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)γ-aminopropyl Aminoalkyl-substituted alkoxysilanes such as propylmethyldiethoxysilane, bis[3-(trimethoxysilyl)propyl]amine, bis[3-(triethoxysilyl)propyl]amine, N,N'-bis[3-(trimethoxysilyl)propyl]ethane-1,2-diamine, N,N'-bis[3-(triethoxysilyl)propyl]ethane-1,2-diamine, and N-phenyl-3-aminopropyltrimethoxysilane; amine compounds such as hexylamine, dodecylamine phosphate, and tetramethylguanidine, and their salts;Quaternary ammonium salts such as benzyltriethylammonium acetate; alkali metal lower fatty acid salts such as potassium acetate, sodium acetate, and lithium oxalate; dialkylhydroxylamines such as dimethylhydroxylamine and diethylhydroxylamine; silanes and siloxanes containing a guanidyl group, such as tetramethylguanidylpropyltrimethoxysilane, tetramethylguanidylpropylmethyldimethoxysilane, tetramethylguanidylpropyltriethoxysilane, tetramethylguanidylpropylmethyldiethoxysilane, and tetramethylguanidylpropyltris(trimethylsiloxy)silane; N,N,N',N',N'',N''-hexamethyl-N'' Examples include silanes and siloxanes containing phosphazene bases such as -[3-(trimethoxysilyl)propyl]-phosphorimidictriamide; and Brønsted acids such as hydrochloric acid, methanesulfonic acid, camphorsulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, dinonylnaphthalene disulfonic acid (DNNDSA), dinonylnaphthalene (mono)sulfonic acid (DNNSA), dodecylbenzenesulfonic acid (DDBSA), phosphoric acid, and nitric acid. These may be used individually or in combination of two or more.

[0037] In the present invention, the addition of a curing catalyst is not essential, but if a curing catalyst is included, it is preferable that the content is 1 part by mass or less of the curing catalyst per 100 parts by mass of the organopolysiloxane. A composition containing a curing catalyst is preferable because it can prevent cracking of the molded product during condensation curing.

[0038] The above curable composition may further contain organic solvents such as methanol, ethanol, isopropyl alcohol, butanol, diacetone alcohol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, acetone, toluene, and xylene, from the standpoint of use and workability. However, since organic solvents are harmful to the human body and may be flammable, a curable composition that is substantially free of organic solvents is preferable. Here, "substantially free" means that the amount of organic solvent contained in the composition is 1% by mass or less, and particularly 0.1% by mass or less, based on the total mass of the composition.

[0039] The curing temperature and time of the above curable composition are not particularly limited, but the curing temperature is preferably 100 to 230°C, and more preferably 150 to 200°C. The curing time is preferably 3 to 48 hours, and more preferably 10 to 36 hours. In one embodiment of the present invention, the optical member can be obtained by heating and curing only a condensation-curing type organopolysiloxane at the above curing temperature and time without using the above curing catalyst.

[0040] One aspect of the present invention is an optical component comprising a cured product of the above-mentioned condensation-curing type organopolysiloxane. Another aspect of the present invention is an optical component comprising a cured product of a curable composition comprising the above-mentioned condensation-curing type organopolysiloxane. The method for manufacturing the optical component is not particularly limited. Regardless of the type of raw material, the shape of the optical component, the degree of surface irregularity, smoothness, width, hardness, and thickness, the above-mentioned organopolysiloxane can be polymerized by injection molding (LIMS), mold molding, stamp molding using a pressing mold or roller, or coating such as spraying or coating to obtain a three-dimensionally crosslinked silicone resin cured product. This makes it possible to obtain a thick film, plate, or three-dimensional optical component with a maximum thickness of 10 mm or less, preferably with a maximum thickness of 5 mm or less.

[0041] The optical component is not particularly limited as long as it includes a cured product of the organopolysiloxane or a cured product of a curable composition containing the organopolysiloxane and has optical properties. The optical component may consist only of a cured product of the organopolysiloxane or a cured product of a curable composition containing the organopolysiloxane. Examples of the optical component include lenses, such as convex lenses like biconvex lenses, plano-convex lenses, and convex meniscus lenses; concave lenses like biconcave lenses, plano-concave lenses, and concave meniscus lenses; aspherical lenses; cylindrical lenses; toroidal lenses; and Fresnel lenses. The optical component may also be a lens sheet in which lenses having the above shapes are arranged on a sheet, or a lens array in which a large number of lenses having the above shapes are arranged. Alternatively, the optical component may be a film or a light guide plate. An example of how the optical component is used is shown in Figure 1. In Figures 1(a) and 1(b), the optical component 1 consists of a cured product 2 of a condensation-curing type organopolysiloxane. For example, Figure 1(a) shows an example where the optical element 1 is a plano-convex lens, and Figure 1(b) shows an example where the optical element 1 is a cylindrical lens.

[0042] The above-mentioned optical component can be bonded to an LED device, optical substrate, substrate, glass surface, LED element, or other optical component molded from a resin different from the optical component of the present invention by surface modification treatment such as corona treatment, plasma treatment, or molecular adhesive, or by adhesive.

[0043] In the present invention, the optical component is more preferably an optical component for an ultraviolet LED. The optical component for an ultraviolet LED is particularly a lens for an ultraviolet LED, which can concentrate, scatter, diffuse, or guide light from an ultraviolet LED, and can adjust the intensity of the light and the area of ​​light irradiation at the target. The light from the ultraviolet LED preferably has a peak wavelength of 200 to 360 nm, preferably 220 to 300 nm, and more preferably 260 to 280 nm. The peak wavelength here refers to the wavelength with the highest intensity.

[0044] The optical component for ultraviolet LEDs may further include another optical substrate formed from the same or different resin as the cured product, or an optical substrate molded from quartz glass or the like. For example, a hybrid lens may be formed in which a coating made from the cured product, or a covering member having the cured product, for example, a covering member having a coating or textured coating on the cured product and possessing light-gathering or light-diffusing properties, covers the optical substrate.

[0045] The optical component for ultraviolet LEDs may be formed solely from the cured material described above, or it may be formed from the cured material and an optical substrate that has a support made of a material such as quartz glass that has high transmittance even in the ultraviolet region and has a three-dimensional shape or plate shape. The method for manufacturing the optical component for ultraviolet LEDs is not particularly limited, but for example, it may be formed by bonding or laminating the cured material and the quartz glass substrate onto a substrate, or by coating the cured material onto the quartz glass substrate and forming it, or by molecular bonding the optical component made of the cured material and the quartz glass substrate. This makes it possible to obtain an optical component for ultraviolet LEDs with a thickness of 10 mm or more.

[0046] Examples of molded optical substrates include optical substrates selected from cubic, rectangular, spherical, hemispherical, prism, spherical lens, and aspherical lens. The present invention may also be a hybrid lens formed from the above optical substrate and the cured material covering at least a portion of the optical substrate.

[0047] Examples of how optical components for ultraviolet LEDs are used are shown in Figures 1(c) to (f). Figures 1(c) and (d) show an embodiment in which the optical component 1 for ultraviolet LEDs is a hybrid lens in which a cubic or rectangular parallelepiped quartz glass substrate 3 is covered with a coating member 2 (a cured product of a condensation-curing organopolysiloxane) having the shape of a plano-convex lens or a Fresnel lens. Figure 1(e) shows an embodiment in which the optical component 1 for ultraviolet LEDs is a hybrid lens in which a spherical quartz glass substrate 3 is covered with a coating member 2 (a cured product of a condensation-curing organopolysiloxane), with one side of the coating member 2 having a rectangular parallelepiped shape and the other side having a convex meniscus lens shape along the upper hemisphere of the spherical surface of the spherical substrate 3. Figure 1(f) shows an embodiment in which the optical component 1 for ultraviolet LEDs is a hybrid lens in which a plano-convex lens, a quartz glass substrate 3, is covered with a film-like coating member 2 (a cured product of condensation-curing organopolysiloxane) along its surface.

[0048] The cured product described above may contain organic or inorganic fillers having light-diffusing, wavelength-converting, or thermal conductivity properties, provided that they satisfy the transmittance requirements described above. Furthermore, the optical component may be provided with a layer separate from the cured product of the condensation-curing type organopolysiloxane of the present invention.

[0049] The optical component may undergo energy irradiation treatment, preferably ultraviolet irradiation treatment, after molding. For example, it is preferable to irradiate with ultraviolet light with a wavelength of 360 nm or less, preferably ultraviolet light with a wavelength of 200 to 360 nm, and more preferably ultraviolet light with a wavelength of 260 to 300 nm. The irradiation energy of the ultraviolet light is 0.04 kJ / cm². ２ Anything above this is acceptable, preferably 0.12 kJ / cm². ２ The above is preferable, and more preferably 0.21 kJ / cm². ２ The above is preferable to 5 kJ / cm². ２ The above, or 40 kJ / cm² ２ The above, or 80 kJ / cm² ２ The above, or 120 kJ / cm² ２The above values ​​are also acceptable. If the ultraviolet irradiation energy is within the above range, the transmittance in the ultraviolet region of the optical material can be improved. The irradiation energy is calculated using the following formula: Irradiation energy [kJ / cm²] ２ ] = Irradiation intensity [mW / cm ２ ]×irradiation time [s]

[0050] As described above, the optical component of the present invention is characterized in that, in a cured product having a thickness of 4 mm, the transmittance of at least one light in the wavelength range of 260 to 280 nm at 25°C is 90% or more, and the cured product having a thickness of 4 mm after being left (stored) for 1000 hours in an environment of 85°C and 85% relative humidity has a transmittance of at least one light in the wavelength range of 260 to 280 nm at 25°C. More preferably, in a cured product having a thickness of 4 mm, the average transmittance of light at wavelengths of 260 nm, 265 nm, 270 nm, 275 nm and 280 nm at 25°C is 90% or more, and the cured product having a thickness of 4 mm after being left (stored) for 1000 hours in an environment of 85°C and 85% relative humidity has an average transmittance of 70% or more of light at wavelengths of 260 nm, 265 nm, 270 nm, 275 nm and 280 nm at 25°C. The above light transmittance can be measured at 25°C using an integrating sphere attachment (e.g., ISR-1503, manufactured by Shimadzu Corporation) and a spectrophotometer (e.g., UV-3600, manufactured by Shimadzu Corporation).

[0051] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The average composition (component unit ratio) was determined using a 500 MHz-NMR measuring device manufactured by JEOL Ltd. １ H-NMR and ２９The weight-average molecular weight (Mw) was calculated from the integrated value of the detection spectrum in Si-NMR. The weight-average molecular weight (Mw) is the polystyrene equivalent value obtained by GPC (gel permeation chromatography) measurement under the following conditions. [GPC conditions] Apparatus: HLC-8220 (manufactured by Tosoh Corporation) Columns: TSKgel GMHXL-L, TSKgel G4000HXL, TSKgel G2000HXL ×2 Developing solvent: Tetrahydrofuran (THF) Flow rate: 1 mL / min Detector: RI Column oven temperature: 40°C Standard substance: Polystyrene

[0052] [Examples 1 and 2] The condensation-curing organopolysiloxane 1 or 2 shown below was placed in a mold in an amount that would result in a cured plate with sides of 20 mm and a thickness of 4 mm, and heated at 160°C for 15 hours to cure. The resulting cured product was removed from the mold to obtain an optical component test sample consisting of a cured product with a thickness of 4 mm. [Examples 3 and 4] A composition was prepared by adding 1 part by mass of DX-9740 (a 1% by mass solution of aluminum-based catalyst manufactured by Shin-Etsu Chemical Co., Ltd.) as a curing catalyst to 100 parts by mass of each of the condensation-curing organopolysiloxane 1 or 2 shown below, and placing the composition in a mold in an amount that would result in a cured plate with sides of 20 mm and a thickness of 4 mm, and heated at 160°C for 15 hours to cure. The resulting cured product was removed from the mold to obtain an optical component test sample consisting of a cured product with a thickness of 4 mm.

[0053] Organopolysiloxane 1: Represented by the following formula (1'), ((CH ３ ) ３ SiO １／２ ) ａ ((CH ３ ) ２ SiO ２／２ ) ｂ (CH ３ SiO ３／２ ) ｃ (CH ３ O １／２ ) ｄ (HO １／２ ) ｅ (1') An organopolysiloxane having a=0.20, b=0.18, c=0.62, and d=0.07, with Mw=20,000 and a hydroxyl group content of 2.5% by mass.

[0054] Organopolysiloxane 2: An organopolysiloxane represented by the above formula (1'), where a = 0.15, b = 0.25, c = 0.60, and d = 0.06, with Mw = 13,000 and a hydroxyl group content of 2.2% by mass.

[0055] [Comparative Examples 1-7] Each of the condensation-curing organopolysiloxanes 3-9 shown below was placed in a mold in an amount that would result in a cured plate with sides of 20 mm and a thickness of 4 mm, and heated and cured at the temperatures and times listed in Table 1. The resulting cured material was removed from the mold to obtain an optical component test sample consisting of a cured material with a thickness of 4 mm.

[0056] Organopolysiloxane 3: An organopolysiloxane represented by the above formula (1'), where a=0, b=0, c=1, and d=0.04, with Mw=3,000 and a hydroxyl group content of 3.6% by mass (similar to the silicone resin described in Example 1 of Patent Document 4).

[0057] Organopolysiloxane 4: An organopolysiloxane represented by the above formula (1'), where a = 0.20, b = 0, c = 0.80, and d = 0.07, with Mw = 1,600 and a hydroxyl group content of 1.3% by mass.

[0058] Organopolysiloxane 5: An organopolysiloxane represented by the above formula (1'), where a = 0.20, b = 0.05, c = 0.75, and d = 0.05, with Mw = 2,600 and a hydroxyl group content of 1.8% by mass.

[0059] Organopolysiloxane 6: An organopolysiloxane represented by the above formula (1'), where a = 0.20, b = 0.10, c = 0.70, and d = 0.08, with Mw = 3,100 and a hydroxyl group content of 2.1% by mass.

[0060] Organopolysiloxane 7: An organopolysiloxane represented by the above formula (1'), where a = 0.15, b = 0.15, c = 0.70, and d = 0.05, with Mw = 9,200 and a hydroxyl group content of 2.3% by mass.

[0061] Organopolysiloxane 8: An organopolysiloxane represented by the above formula (1'), where a = 0.10, b = 0.40, c = 0.50, and d = 0.08, with Mw = 8,000 and a hydroxyl group content of 3.1% by mass.

[0062] Organopolysiloxane 9: An organopolysiloxane represented by the above formula (1'), where a = 0.10, b = 0.60, c = 0.30, and d = 0.06, with Mw = 7,500 and a hydroxyl group content of 2.9% by mass.

[0063] The following evaluations were performed on each optical component test sample, which consisted of a cured material with a thickness of 4 mm, obtained in the above examples and comparative examples. The results are shown in Table 1.

[0064] [Cracking] The presence or absence of cracking (a phenomenon in which the molded product is physically damaged) at 25°C was checked during the hardening process and the process of removing the hardened product from the mold. The results are shown in Table 1.

[0065] [Light Transmittance] The optical component test samples obtained in the above examples and comparative examples were subjected to transmittance measurements at wavelengths of 200 to 800 nm at 25°C using a UV-3600Plus spectrophotometer (manufactured by Shimadzu Corporation) and an ISR-1503 integrating sphere attachment (manufactured by Shimadzu Corporation). The transmittance of light at 260 nm, 265 nm, 270 nm, 275 nm, and 280 nm was measured. The average value of the obtained transmittances was calculated and defined as the average transmittance (I) at wavelengths of 260 to 280 nm. The results are shown in Table 1.

[0066] [High Temperature and High Humidity Resistance] Each optical component test sample obtained in the above examples and comparative examples was left standing for 1,000 hours in a constant temperature bath set to a temperature of 85°C and a relative humidity of 85% RH. Immediately after 1,000 hours, each optical component test sample was cooled to 25°C, and the light transmittance at 260 nm, 265 nm, 270 nm, 275 nm, and 280 nm was measured using the same method as the measurement of [Light Transmittance] above. The average value of the obtained transmittances was also calculated and defined as the average transmittance (II) for wavelengths of 260 to 280 nm. The results are shown in Table 1.

[0067] [Cracks] Each optical component test sample obtained in the above examples and comparative examples was left standing for 1,000 hours in a constant temperature bath set to a temperature of 85°C and a relative humidity of 85% RH. Immediately after 1,000 hours, each optical component test sample was cooled to 25°C, and its appearance was visually observed to check for the presence or absence of cracks (whitening phenomenon due to fine cracks inside the sample). The results are shown in Table 1.

[0068]

[0069] As shown in Table 1, the optical components of Comparative Examples 1 to 5, which consist of cured organopolysiloxanes in which the ratio of the number of D units to the total number of M units, D units, and T units (the value of b / (a+b+c) in formula (1)) is 0.15 or less, develop internal cracks after a high-temperature, high-humidity test at 85°C, 85% RH, and 1000 hours. This is thought to be because the stress relaxation of the cured material is insufficient. Furthermore, the optical components of Comparative Examples 1 to 4, which consist of cured organopolysiloxanes in which the value of b / (a+b+c) in formula (1) is 0.10 or less, all exhibit high transmittance, with an average transmittance of 90% or more at wavelengths of 260-280 nm at 25°C, but after the high-temperature, high-humidity test, the average transmittance at wavelengths of 260-280 nm decreases to 70% or less. Furthermore, in Comparative Examples 6 and 7, the optical components made of cured organopolysiloxanes in which the ratio of the number of D units to the total number of M units, D units, and T units (b / (a+b+c)) is 0.4 or higher, show suppressed reduction in transmittance and crack formation inside the optical components during high-temperature and high-humidity tests, but cracks occur when the optical components are demolded from the mold. This is thought to be because, although the stress relaxation effect in the cured material is good, the strength of the molded product is insufficient due to the excessively high content of D units.

[0070] On the other hand, as shown in Table 1, the optical members of Examples 1 to 4 obtained from the cured product of the organopolysiloxane of the present invention exhibit high transmittance, with an average transmittance of 90% or more at wavelengths of 260 to 280 nm at 25°C, and maintain good high transmittance, with an average transmittance of 70% or more at wavelengths of 260 to 280 nm even after a high-temperature, high-humidity test at 85°C, 85% RH for 1000 hours. Furthermore, crack formation inside the optical members during the high-temperature, high-humidity test is suppressed, and no cracks occur during molding. This is thought to be because the cured product of the present invention has a good stress relaxation effect.

[0071] The optical components of the present invention exhibit excellent ultraviolet transmittance and maintain good ultraviolet transmittance even when exposed to high temperature and high humidity environments for extended periods, thus providing superior reliability. The optical components of the present invention are suitable as optical components for ultraviolet LEDs, such as lenses, lens sheets, lens arrays, films, and light guide plates.

[0072] 1. Optical components (optical components for ultraviolet LEDs) 2. Cured products of condensation-curing organopolysiloxanes (coating components) 3. Quartz glass substrates

Claims

1. The following formula (1) (R １ ３ SiO １／２ ) ａ (R ２ ２ SiO ２／２ ) ｂ (R ３ SiO ３／２ ) ｃ (R ４ O １／２ ) ｄ (HO １／２ ) ｅ (1) (wherein, R １ , R ２ and R ３ are each independently a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms, R ４ is a monovalent saturated hydrocarbon group having 1 to 4 carbon atoms, a, b and c are numbers satisfying a>0, 0.15<b≦0.30, c>0, and a+b+c=1, d is a number satisfying 0≦d / (a+2b+3c)≦0.1, and e is a number satisfying 0<e), the optical member comprising a cured product of a condensation-curable organopolysiloxane represented by the formula, wherein the cured product having a thickness of 4 mm has a transmittance of 90% or more for at least one light in the wavelength range of 260 to 280 nm at 25°C, and the cured product having a thickness of 4 mm has a transmittance of 70% or more for at least one light in the wavelength range of 260 to 280 nm at 25°C, the transmittance being measured after the cured product is left for 1000 hours in an environment at a temperature of 85°C and a relative humidity of 85% RH. The optical member as described above.

2. The optical member according to claim 1, wherein the condensation-curable organopolysiloxane has hydroxyl groups in an amount of 1.0 to 5.0% by mass relative to the mass of the condensation-curable organopolysiloxane.

3. The optical member according to claim 1, wherein the condensation-curing organopolysiloxane has a weight-average molecular weight of 10,000 to 30,000.

4. The optical member according to claim 1, wherein in formula (1), a is a number between 0.10 and 0.30, b is a number greater than 0.15 and less than or equal to 0.30, c is a number between 0.50 and less than 0.82, and a + b + c = 1.

5. The optical member according to claim 1, wherein the cured product having a thickness of 4 mm has an average transmittance of 90% or more for light at wavelengths of 260 nm, 265 nm, 270 nm, 275 nm and 280 nm at 25°C, and the average transmittance of the cured product having a thickness of 4 mm, measured for 1000 hours in an environment of 85°C and 85% RH, for light at wavelengths of 260 nm, 265 nm, 270 nm, 275 nm and 280 nm at 25°C is 70% or more.

6. The optical member according to claim 1, wherein the cured product is a cured product of a curable composition containing the condensation-curing type organopolysiloxane and a curing catalyst.

7. An optical component for ultraviolet LEDs, as described in any one of claims 1 to 6.

8. The optical component for an ultraviolet LED according to claim 7, further comprising an optical substrate.

9. The optical component for an ultraviolet LED according to claim 8, wherein the optical substrate is a quartz glass substrate.

Images