Cured products of addition-curing silicone rubber compositions and optical components for ultraviolet irradiation devices

Abstract

This invention provides a cured silicone rubber composition that exhibits minimal degradation from irradiation with deep ultraviolet light and possesses high durability. [Solution] The cured product of the addition-curing type silicone rubber composition is 13 In the C-MAS-NMR spectrum, the ratio of the area of ​​peak B to the sum of the areas of peak A appearing at 18.0–18.5 ppm and peak B appearing at 9.0–10.0 ppm is between 31% and 68%.

Description

Technical Field

[0001] The present invention relates to a cured product of an addition-curable silicone rubber composition and an optical component for an ultraviolet irradiation device.

Background Art

[0002] Ultraviolet irradiation devices using light sources such as LEDs that emit deep ultraviolet light with a wavelength of 300 nm or less are used in various devices for disinfection, sterilization, purification, and the like. In such devices, a light beam control member is used to spread the light emitted from the light source into a distribution suitable for the irradiation target.

[0003] As general-purpose molding materials used in optical applications, polymethyl methacrylate (PMMA) and polycarbonate (PC) are known. However, since these resin materials are difficult to transmit ultraviolet light, they cannot be used as molding materials for the above light beam control members. Therefore, expensive and difficult-to-process materials such as quartz and fluororesin are used.

[0004] [[ID=·20]]On the other hand, addition-curable silicone rubber compositions have been studied as molding materials having ultraviolet light transmissibility. For example, Patent Document 1 discloses using a cured product of an addition-curable silicone rubber composition containing an organopolysiloxane having an alkenyl group bonded to a silicon atom, an organohydrogenpolysiloxane having a hydrogen atom bonded to a silicon atom, and a catalyst as an optical component.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, our investigations have revealed that the cured product obtained in Patent Document 1 is prone to degradation by irradiation with ultraviolet light, particularly deep ultraviolet light, and has low durability. Therefore, when the above cured product is irradiated with ultraviolet light for a certain period of time, its transmittance decreases, and the desired light distribution cannot be obtained.

[0007] The object of the present invention is to provide a cured silicone rubber composition that exhibits less degradation due to irradiation with deep ultraviolet light and has high durability, as well as an optical component for an ultraviolet irradiation device using the same. [Means for solving the problem]

[0008] The present invention relates to the following cured products and optical components for ultraviolet irradiation devices.

[0009] [1] A cured product of an addition-curing type silicone rubber composition, 13 A cured product in which, in the C-MAS-NMR spectrum, the ratio of the area of ​​peak B to the sum of the area of ​​peak A appearing at 18.0-18.5 ppm and the area of ​​peak B appearing at 9.0-10.0 ppm is 31% or more and 68% or less. [2] A cured product of an addition-curing silicone rubber composition, wherein the ATR-FTIR absorption spectrum is 2120-2180 cm⁻¹ -1 A cured product in which the concentration of hydrosilyl groups in the cured product, calculated from the peak derived from the hydrosilyl group appearing therein, is 0.20 mmol / g or more and 0.54 mmol / g or less. [3] In the ATR-FTIR absorption spectrum, 1630–1670 cm⁻¹ -1 The cured product according to [1] or [2], wherein the peak derived from the vinyl group that appears is undetectable. [4] The addition-curing silicone rubber composition is (A) an organopolysiloxane having an average composition represented by formula (1), formula (1):R 1 a SiO (4-a) / 2 (In the formula, R 1R is an alkenyl group, an alkyl group having 1 to 6 carbon atoms, an alkyl fluoride having 1 to 6 carbon atoms, an aryl group, or a cycloalkyl group having 5 to 12 carbon atoms, and is contained in one molecule. 1 (B) an organohydrogenpolysiloxane having at least two of the groups being alkenyl groups, where a is a positive number between 1.95 and 2.05, and (C) a curing catalyst, comprising any one of the cured products according to [1] to [3]. An optical component for an ultraviolet irradiation device, comprising a cured product as described in any of [5][1] to [4]. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a cured silicone rubber composition that exhibits less degradation due to irradiation with deep ultraviolet light and has high durability, as well as an optical component for an ultraviolet irradiation device using the same. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing an ultraviolet irradiation device according to this embodiment. [Figure 2] Figure 2A is a plan view of an ultraviolet irradiation apparatus according to another embodiment, and Figure 2B is a cross-sectional view along line BB in Figure 2A. [Figure 3] Figure 3 shows a schematic configuration of the equipment used in the ultraviolet irradiation test. [Figure 4] Figure 4 shows the 13C-MAS-NMR spectrum of Example 4. [Figure 5] Figures 5A and 5B show the ATR-FTIR absorption spectra of Examples 1 to 4. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof. In addition, the numerical range represented by "~" in this specification means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0013] 1. Cured product The cured product of this embodiment is a cured product of an addition-curable silicone rubber composition. The addition-curable silicone rubber composition contains an organopolysiloxane component having an unsaturated bond (for example, a structure of -Si-CH=CH2) and an organohydrogenpolysiloxane component having a hydrosilyl group (-SiH), and when heated in the presence of a catalyst, these components undergo a hydrosilylation reaction and cure.

[0014] 13 C-MAS-NMR The inventors of the present invention have found that even for cured products obtained from the same material, the susceptibility to deterioration by deep ultraviolet rays differs depending on the magnitude of the heat history received by the product until it is obtained after the curing process and curing of the material. And when further analyzing a plurality of cured products with different susceptibilities to deterioration by deep ultraviolet rays, 13 in the C-MAS-NMR spectrum, it has been clarified that a cured product in which the ratio of the area of peak B appearing at 9.0 to 10.0 ppm to the total area of peak A appearing at 18.0 to 18.5 ppm and peak B appearing at 9.0 to 10.0 ppm is below a predetermined value has less deterioration by deep ultraviolet rays (see FIG. 4 described later).

[0015] The reason for this is not clear, but it is presumed as follows. ​In the addition curing reaction of silicone rubber compositions, for example, organopolysiloxane components having a -Si-CH=CH2 structure undergo hydrosilylation with organohydrogenpolysiloxane components having a hydrosilyl group (-Si-H), generating a crosslinked structure (see (1) and (2) below). On the other hand, some of the organopolysiloxane components having a -Si-CH=CH2 structure are thought to remain unreacted (see (3) below). [ka]

[0016] 13 In the C-MAS-NMR spectrum, peak A, which appears at 18.0–18.5 ppm, originates from cross-linked structure (2), and this cross-linked structure (2) is stable against deep ultraviolet light (see peak A in Figure 4, described later). On the other hand, peak B, which appears at 9.0–10.0 ppm, originates from cross-linked structure (1), and this cross-linked structure (1) is unstable against deep ultraviolet light (see peak B in Figure 4, described later). In other words, if the area ratio of peak B is below a certain level, the amount of unstable cross-linked structure (1) in the cured product is relatively small, and the amount of stable cross-linked structure (2) is relatively large, so it is thought that degradation against deep ultraviolet light can be suppressed.

[0017] In other words, the hardened product is 13 In the C-MAS-NMR spectrum, the ratio of the area of ​​peak B appearing at 9.0–10.0 ppm to the sum of the areas of peak A appearing at 18.0–18.5 ppm and peak B appearing at 9.0–10.0 ppm (hereinafter also referred to as the "area ratio of peak B") is between 31% and 68%.

[0018] When the area ratio of peak B in the cured product is 68% or less, as described above, there are relatively few unstable cross-linked structures (1) and relatively many stable cross-linked structures (2), making it less susceptible to degradation by deep ultraviolet light. Preferably, the area ratio of peak B is between 35% and 65%.

[0019] hardened material 13C-MAS-NMR measurement can be carried out according to the following procedure. First, cut the cured product to be measured into a size of 0.5 - 1.0 mm square to obtain a sample. Next, fill the sample into the center of a solid NMR sample tube, and subject it to a solid NMR measuring device (for example, VNMRS - 400 manufactured by Varian), and 13 perform C-MAS-NMR measurement under the following conditions. (Measurement conditions) Observed nucleus: 13 C Observation frequency: 100.5 MHz Measurement method: DDMAS Reference substance: Adamantane Pulse width: 2.7 μsec Waiting time: 15 sec Number of integrations: 5800 times Rotation frequency (MAS rotation speed): 15 kHz Sample temperature: 23 °C

[0020] The processing of NMR data can be carried out using commercially available NMR data processing software (for example, Delta v6.0 manufactured by JEOL Ltd. of Japan, etc.). For example, baseline correction can be carried out using the automatic baseline correction function of commercially available NMR data processing software (for example, the "Base Correct" function of Delta v6.0 manufactured by JEOL Ltd. of Japan).

[0021] 13 The area ratio of peak B in the C-MAS-NMR spectrum can be adjusted according to the thermal history of the cured product, particularly the heating temperature and heating time during the curing reaction. Specifically, the area ratio of peak B increases with the increase in thermal history. Therefore, within the range where there is no hindrance to curing, by reducing the heating temperature or shortening the heating time to reduce the thermal history, the area ratio of peak B can be reduced.

[0022] [ATR-FTIR] When the inventors further advanced the analysis, in the absorption spectrum of ATR-FTIR of the cured product, 2120 - 2180 cm <0000 = 017>It was also revealed that cured products with a hydrosilyl group concentration of 0.20 mmol / g to 0.54 mmol / g, calculated from the peaks derived from hydrosilyl groups appearing in the sample, also exhibited less degradation from ultraviolet light.

[0023] The reason for this is not clear, but it can be inferred as follows: According to the inventors' studies, the concentration of hydrosilyl groups in the cured product decreases with increasing thermal history. In other words, when the concentration of hydrosilyl groups is 0.20 mmol / g or higher, the thermal history is not too great, making it difficult to form an unstable cross-linked structure (1) and making it less susceptible to degradation from deep ultraviolet light. From a similar viewpoint, the concentration of hydrosilyl groups in the cured product is preferably 0.24 mmol / g or higher, and more preferably 0.26 mmol / g or higher.

[0024] Furthermore, the organopolysiloxane component having unsaturated bonds and the organohydrogenpolysiloxane component having hydrosilyl groups react in a 1:1 ratio. Therefore, when the charging ratio of the organopolysiloxane component having unsaturated bonds and the organohydrogenpolysiloxane component having hydrosilyl groups is 1:1, if the concentration of hydrosilyl groups in the cured product is 0.54 mmol / g or less, the concentration of vinyl groups derived from the organopolysiloxane component having unsaturated bonds will also be correspondingly low, thus making yellowing less likely and reducing degradation by deep ultraviolet light. From a similar viewpoint, it is preferable that the concentration of hydrosilyl groups in the cured product be 0.50 mmol / g or less (see Figure 5B described later).

[0025] Furthermore, from the viewpoint of reducing yellowing when irradiated with deep ultraviolet light and making degradation less likely, it is preferable that the concentration of unreacted vinyl groups (as described in (3) above) in the cured product be low. Specifically, in the ATR-FTIR absorption spectrum of the cured product, the concentration should be between 1630 and 1670 cm⁻¹. -1It is preferable that the peaks originating from vinyl groups appearing in the spectrum are undetectable (see Figure 5A, described later). Undetectable peaks mean that the spectrum is broadened and cannot be detected as peaks (the concentration of vinyl groups calculated from the peaks is below the detection limit of the measuring device).

[0026] Furthermore, the concentration of unreacted vinyl groups in the cured product can also be estimated from the concentration of unreacted hydrosilyl groups in the cured product. As mentioned above, the starting ratio of organopolysiloxane components having unsaturated bonds and organohydrogenpolysiloxane components having hydrosilyl groups is usually close to 1:1, and the two react in a 1:1 ratio.

[0027] ATR-FTIR (Attenuation by Radiography) spectroscopy of the cured material can be performed using the following procedure. (Measurement conditions) Equipment: Fourier transform infrared spectrophotometer (e.g., Agilent Cary 620 FTIR from Agilent Technologies) Measurement method: Micro-ATR method ATR prism: Germanium (spherical) Refractive index 4.0 Incident angle: 30° Measurement area: 650~4000cm -1 Detector: MCT, High Sensitivity 100μm Number of reflections: 1 Resolution: 4cm -1 Total number of times: 128

[0028] Background measurements are performed in the same manner, except that the sample is not in contact with the prism. In addition, in the ATR method, the intensity of the absorption spectrum obtained changes depending on the degree of contact between the sample and the ATR prism, so the measurement is performed so that the maximum peak intensity is between 0.33 and 0.34.

[0029] Then, in the resulting absorption spectrum, at 1350 cm⁻¹ -1 and 926cm -1After defining these as the starting points on the left and right sides of the baseline, respectively, 1013cm -1 Height h of the peak originating from the Si-O bond in the vicinity ref Calculate the value. Also, 2193cm -1 and 2080cm -1 After defining these as the starting points on the left and right sides of the baseline, respectively, 2138cm -1 Peak height h originating from nearby hydrosilyl groups SiH Calculate the following. Then, substitute these values ​​into the following formula to calculate the concentration of the hydrosilyl group (SiH concentration). SiH concentration [mmol / g] = 30.2 × h SiH / h ref +0.021 The above formula is a calibration curve obtained from the absorption spectra obtained by ATR-FTIR measurements of samples with known SiH concentrations.

[0030] The concentrations of vinyl groups and hydrosilyl groups in the cured product can also be adjusted in the same way as described above, by controlling the thermal history, particularly the curing temperature and curing time during the curing reaction. For example, increasing the heating temperature or heating time will increase the thermal history, thereby lowering the concentrations of hydrosilyl groups and vinyl groups.

[0031] Thus, 13 The area ratio of peak B in the C-MAS-NMR spectrum and the concentrations of vinyl and hydrosilyl groups measured from the ATR-FTIR absorption spectrum can be adjusted by the thermal history of the cured product. Therefore, the silicone rubber composition is not particularly limited as long as it undergoes an addition curing reaction, and known compositions can be used. The components of the silicone rubber composition will be described in detail below.

[0032] [Silicone rubber composition] The silicone rubber composition comprises (A) an organopolysiloxane having at least two alkenyl groups in one molecule, (B) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule, and (C) a curing catalyst.

[0033] <(A) component> Component (A) is an organopolysiloxane having at least two alkenyl groups, preferably alkenyl groups bonded to silicon atoms, in one molecule, and functions as the main component of the silicone rubber composition. The average composition of the organopolysiloxane is shown by formula (1). Formula (1):R 1 a SiO (4-a) / 2

[0034] R in equation (1) 1 R is an alkenyl group, an alkyl group having 1 to 6 carbon atoms, an alkyl fluoride having 1 to 6 carbon atoms, an aryl group, or a cycloalkyl group having 5 to 12 carbon atoms. However, the amount of R contained in one molecule is limited. 1 At least two of these R are alkenyl groups. 1 This substituent does not absorb UVC.

[0035] Examples of alkenyl groups include vinyl, allyl, butenyl, pentenyl, and hexenyl groups, with vinyl being preferred. The alkenyl group may be located at the end of the molecular chain or in the side chain.

[0036] Examples of alkyl groups having 1 to 6 carbon atoms include methyl, ethylene, propyl, and butyl groups. Examples of fluorinated alkyl groups having 1 to 6 carbon atoms include groups in which some of these alkyl groups are substituted with fluorine atoms. Aryl groups are preferably aryl groups having 6 to 12 carbon atoms, and examples include phenyl and tolyl groups. By appropriately adjusting the concentration of aryl groups, the absorption of deep ultraviolet light can be further suppressed. Examples of cycloalkyl groups having 5 to 12 carbon atoms include cyclohexyl and cyclohexenyl groups.

[0037] In equation (1), 'a' is a positive number between 1.95 and 2.05.

[0038] The organopolysiloxane represented by formula (1) is preferably linear, but may contain a partially branched structure. That is, the organopolysiloxane represented by formula (1) preferably contains diorganosiloxane units (D units) as its main component. Specifically, the D unit content is preferably 90 mol% or more relative to the total constituent units (total siloxane units) of the organopolysiloxane. The type and amount of siloxane units are as follows: 29 It can be identified by analysis using Si-NMR. Furthermore, the organopolysiloxane represented by formula (1) is preferably in liquid form at 25°C.

[0039] The organopolysiloxane represented by formula (1) is preferably a linear organopolysiloxane in which the main chain mainly consists of diorganosiloxane units (D units) and both ends of the molecular chain are sealed with triorganosiloxane units (M units). 1 Of these, groups other than the alkenyl group preferably contain a methyl group. The alkenyl group is preferably a vinyl group.

[0040] The alkenyl group content of the organopolysiloxane represented by formula (1) is not particularly limited, but is preferably 0.02 mmol / g or more, and more preferably 0.05 mmol / g or more. When the alkenyl group content is 0.02 mmol / g or more, the crosslinking density of the cured product becomes higher, making it easier to increase the hardness. The upper limit of the alkenyl group content is preferably less than 1.0 mmol / g, and more preferably less than 0.8 mmol / g. When the alkenyl group content is less than 1.0 mmol / g, the crosslinking density of the cured product is less likely to become excessively high, so the elongation at break of the cured product is less likely to be impaired, and the toughness is less likely to be impaired. The organopolysiloxane represented by formula (1) may be two or more types with different alkenyl group content in the mixture, as long as the alkenyl group content of the mixture is within the above range.

[0041] The content of component (A) is preferably 40 to 98% by mass, and more preferably 50 to 95% by mass, relative to the silicone rubber composition. When the content of component (A) is above a certain level, the moldability is even better, and a cured product with appropriate hardness is more likely to be obtained.

[0042] <(B) component> Component (B) is an organohydrogenpolysiloxane having at least two hydrogen atoms (-SiH) bonded to silicon atoms in one molecule, and can function as a crosslinking agent for component (A).

[0043] The organohydrogenpolysiloxane may be linear or branched. The degree of polymerization of the organohydrogenpolysiloxane is not particularly limited, but is, for example, 2 to 300, preferably 4 to 200. The hydrogen atoms bonded to the silicon atoms may be at the ends of the molecular chain or in the side chains.

[0044] The organic group bonded to the silicon atom is an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 5 to 12 carbon atoms. Among these, alkyl groups having 1 to 6 carbon atoms are preferred, and methyl groups are more preferred.

[0045] The hydrogen atom content of the organohydrogenpolysiloxane bonded to the silicon atom is not particularly limited as long as it can react sufficiently with the alkenyl group of component (A), but it is preferably 0.1 mmol / g to 20 mmol / g.

[0046] Examples of organohydrogenpolysiloxanes include diorganopolysiloxanes encapsulated with dimethylhydrogensilyl groups, copolymers containing dimethylsiloxane units, methylhydrogensiloxane units, and terminal trimethylsiloxy groups, and dimethylhydrogensiloxane units and SiO 4 / 2This includes low-viscosity polymers containing units (Q units), such as 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trihydrogen-1,3,5,7-tetramethylcyclotetrasiloxane, and 1,5-dihydrogen-3,7-dihexyl-1,3,5,7-tetramethylcyclotetrasiloxane.

[0047] The content of component (B) is not particularly limited as long as it can sufficiently crosslink component (A), but it is preferable that the number of moles of hydrosilyl groups of component (B) is 0.8 to 5 moles, and more preferably 1 to 3 moles, per mole of alkenyl groups of component (A).

[0048] <(C) component> Component (C) is a catalyst for promoting the hydrosilylation reaction between component (A) and component (B). Known hydrosilylation catalysts can be used as such catalysts. Examples include platinum black, dic platinum chloride, chloroplatinic acid, reaction products of chloroplatinic acid and monohydric alcohols, complexes of chloroplatinic acid and olefins, palladium-based catalysts, rhodium-based catalysts, and the like.

[0049] The content of component (C) is not particularly limited, but for example, it is preferably 0.5 ppm to 300 ppm of platinum atoms per 100 parts by mass of the total of components (A) and (B), more preferably 1 ppm to 200 ppm, and even more preferably 2 ppm to 100 ppm.

[0050] <Other ingredients> The silicone rubber composition may further contain other components as needed. Examples of other components include organopolysiloxanes containing alkenyl groups other than component (A) (e.g., (D) silicone resin), (E) silica particles, and (F) hydrosilylation reaction regulators.

[0051] ((D) component) (D) component is R2 SiO 3 / 2 Units (T units) and SiO 4 / 2 A silicone resin containing at least one of the units (Q units) and having at least two alkenyl groups in one molecule. 2 R is a monovalent hydrocarbon group having 1 to 6 carbon atoms. Because such silicone resins have a three-dimensional network structure, the hardness of the cured silicone rubber composition can be further increased. 2 Preferably, at least two of these are alkenyl groups. The total amount of T units and Q units may be 50 mol% or more of the total constituent units of the silicone resin.

[0052] Examples of monovalent hydrocarbon groups having 1 to 6 carbon atoms include alkyl groups, cyclohexyl groups, cyclohexenyl groups, and alkenyl groups. C1-C6 alkyl groups are preferably methyl groups. Alkenyl groups are preferably vinyl groups.

[0053] Examples of silicone resins include R 2 3SiO 1 / 2 Units (M units) and SiO 4 / 2 Silicone resin containing units (Q units), R 2 SiO 3 / 2 Units (T units) and SiO 4 / 2 Silicone resin containing units (Q units), R 2 SiO 3 / 2 This includes silicone resins consisting of units (T units). Specific examples include copolymers of vinyldimethylsiloxy groups and Q units, copolymers of vinyldimethylsiloxy groups / trimethylsiloxy groups and Q units, copolymers of vinyldimethylsiloxy groups / dimethylsiloxane and Q units, and copolymers of trimethylsiloxy groups / vinylmethylsiloxane and Q units.

[0054] The content of component (D) can be, for example, 5 to 50 parts by mass per 100 parts by mass of component (A).

[0055] ((E) component) Silica particles (E) may be added to enhance the ultraviolet diffusion effect of the cured product and to provide the cured product with sufficient tear strength and strength. The type of silica particles (E) is not particularly limited, but gel silica or fumed silica is preferred, and hydrophobized fumed silica particles are more preferred, in terms of not interfering with the catalytic function of component (C). Hydrophobized silica particles may be silica particles surface-treated with a silane coupling agent, silazane compound, or low molecular weight siloxane compound having hydrophobic groups.

[0056] The average primary particle diameter of the silica particles (E) is preferably 5 to 300 nm, more preferably 5 to 100 nm. When the average primary particle diameter is 5 nm or more, the ultraviolet diffusion effect is improved, and a sufficient improvement in mechanical strength is easily obtained. When the average primary particle diameter is 300 nm or less, the decrease in ultraviolet transmittance can be further suppressed.

[0057] The content of component (E) is preferably 1 to 20 parts by mass, and more preferably 2 to 10 parts by mass, per 100 parts by mass of component (A).

[0058] (Component F) The silicone rubber composition may further contain a hydrosilylation reaction regulator ('F') from the viewpoint of ensuring pot life. Examples of hydrosilylation reaction regulators include polyfunctional alkenyl compounds such as 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, and acetylene alcohol derivatives such as 2-methyl-3-butyne-2-ol, 3-methyl-1-butyne-3-ol, and 3-methyl-1-pentin-3-ol.

[0059] The content of component (F) is preferably 0.001 to 0.05 parts by mass, and more preferably 0.001 to 0.02 parts by mass, per 100 parts by mass of component (A).

[0060] 2. Method for manufacturing cured products As described above, the cured product can be obtained by heating and curing the addition-curing type silicone rubber composition. In this embodiment, the cured product is obtained through a process of molding the addition-curing type silicone rubber composition and an annealing process, and the heating conditions (heating temperature, heating time) in the molding process and the annealing process can be adjusted so that the area ratio of peak B described above satisfies the above range.

[0061] The molding method is not particularly limited and examples include injection molding and press molding. For example, in the case of press molding, the silicone rubber composition is poured into a mold, pressurized and heated under predetermined conditions, and then further annealed in a constant temperature oven or the like. By adjusting the heating conditions (heating temperature, heating time) in the molding and annealing processes, the area ratio of peak B in the NMR spectrum of the resulting cured product can be adjusted. In particular, it is preferable to make the heating conditions in the annealing process milder than conventional general conditions. For example, when curing at 80 to 160°C, it is preferable to shorten the heating time compared to conventional general conditions (for example, less than 1 hour, preferably 45 minutes or less, more preferably 30 minutes or less).

[0062] The resulting cured product, when formed into a 1 mm thick flat plate, preferably has a transmittance of 70% or more, more preferably 80% or more, even more preferably 85% or more, and most preferably 88% or more, when measured with an ultraviolet-visible-near-infrared spectrophotometer. Furthermore, it is preferable that the transmittance of light with a central wavelength of 265 nm after irradiation for 400 hours from a distance of 1 mm from a UVC-LED light source is 88% or more. Cured products having such light transmittance can be suitably used as optical components.

[0063] 3.Applications The cured material has good resistance to ultraviolet light. Therefore, the cured material is suitable as an optical component, especially as an optical component used in an ultraviolet irradiation device that uses a light source that emits ultraviolet light. The type of optical component used in an ultraviolet irradiation device is not particularly limited and may be, for example, a sealing member, an adhesive member, a transmitting member that transmits ultraviolet light, or a light beam control member that controls the distribution of ultraviolet light.

[0064] The following describes an ultraviolet irradiation device according to one embodiment of the present invention.

[0065] Figure 1 is a schematic diagram showing the ultraviolet irradiation device 100 of this embodiment. As shown in Figure 1, the ultraviolet irradiation device 100 includes a substrate 110, a light source 120 that emits ultraviolet light, an ultraviolet-transmitting window member 130, and a resin adhesive layer 140. The ultraviolet-transmitting window member 130 and the resin adhesive layer 140 are optical components used in the ultraviolet irradiation device, and at least one of them contains the cured material.

[0066] The type of substrate 110 is not particularly limited, but it may be a multilayer substrate such as a low-temperature co-fired ceramic (LTCC) substrate or a high-temperature co-fired ceramic (HTCC) substrate. In this embodiment, the substrate 110 has a recess 110a that houses a light source 120 that emits ultraviolet light.

[0067] A light source 120 that emits ultraviolet light is mounted on a substrate 110. In this embodiment, the light source 120 is located in a recess 110a. The light source 120 that emits ultraviolet light is not particularly limited as long as it emits ultraviolet light, and examples include light-emitting diodes (LEDs), mercury lamps, metal halide lamps, xenon lamps, and laser diodes (LDs). In this embodiment, the light source 120 is a light-emitting element such as a light-emitting diode (LED). The central wavelength of the ultraviolet light emitted from the light source 120 is preferably 200 to 350 nm, and more preferably 240 to 300 nm from the viewpoint of easily obtaining desired effects such as sterilization efficiency. That is, the ultraviolet light is more preferably ultraviolet C (UVC).

[0068] The ultraviolet-transmitting window member 130 is a member that transmits ultraviolet light emitted from the light source 120. In this embodiment, the ultraviolet-transmitting window member 130 covers the recess 110a of the substrate 110 and is positioned to face the light-emitting surface of the light source 120 within the recess 110a (see Figure 1). The material of the ultraviolet-transmitting window member 130 can be any material that transmits ultraviolet light (especially deep ultraviolet light), and may be the cured product described above, or it may be quartz glass, sapphire, MgO, MgF2, CaF2, synthetic phased silica, etc.

[0069] The resin adhesive layer 140 may be a sealing member positioned between the substrate 110 and the ultraviolet-transmitting window member 130. In this embodiment, the material of the resin adhesive layer 140 is not particularly limited and may be the cured product described above, or it may be an acrylic resin, epoxy resin, silicone resin, organic / inorganic (e.g., silicone / silica) hybrid resin, fluororesin, etc.

[0070] The distance d between the ultraviolet-transmitting window member 130 and the light-emitting surface of the light source 120 on the optical axis LA of the light source 120 is not particularly limited, but can be, for example, 0.1 to 10 mm, preferably 0.5 to 5 mm (see Figure 1). Here, "optical axis LA of the light source 120" refers to the light ray at the center of the three-dimensional emitted light beam from the light source 120.

[0071] According to the ultraviolet irradiation device 100 of the above embodiment, at least one of the ultraviolet-transmitting window member 130 and the resin adhesive layer 140 includes the cured product. Therefore, these optical components are less likely to deteriorate even when irradiated with ultraviolet light (e.g., UVC) for a long period of time.

[0072] In the above embodiment, the ultraviolet irradiation device shown is that of Figure 1, but it is not limited to this, and any device having a light source that emits ultraviolet light is acceptable. In other words, the optical components for the ultraviolet irradiation device are not limited to the ultraviolet-transmitting window member 130 or the resin adhesive layer 140, but any component that is required to suppress deterioration such as discoloration due to ultraviolet light is acceptable.

[0073] For example, the cured material may be used in an optical control member for controlling the light distribution of ultraviolet light. Such an optical control member may be a focusing lens, a diffusing lens, a total reflection lens, or a hemispherical lens for controlling the light distribution of ultraviolet light emitted from a light source.

[0074] Figures 2A and 2B show ultraviolet irradiation devices 100 according to other embodiments. Figure 2A is a plan view, and Figure 2B is a cross-sectional view along line BB in Figure 2A. Components identical or similar to those in Figure 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0075] As shown in Figure 2B, the ultraviolet irradiation device 100 includes a substrate 110, a light source 120 that emits ultraviolet light, and a light beam control member 230 (optical component) arranged on the light source 120.

[0076] The luminous flux control member 230 is a member that controls the light distribution of ultraviolet light emitted from a light source 120 that emits ultraviolet light, and is positioned opposite the light-emitting surface of the light source 120 (see Figure 2B). The luminous flux control member 230 has an incident surface 231 and an outgoing surface 232. In this embodiment, the incident surface 231 and the outgoing surface 232 are rotationally symmetric with respect to the central axis CA of the luminous flux control member 230. The luminous flux control member 230 can be positioned on the light source 120 such that the central axis CA of the luminous flux control member 230 coincides with the optical axis LA of the light source 120. The distance d between the incident surface 231 and the light-emitting surface of the light source 120 on the optical axis LA of the light source 120 can also be the same as described above.

[0077] Thus, optical components containing a cured silicone rubber composition are also suitable as optical control members for controlling the light distribution of ultraviolet rays in an ultraviolet irradiation device 100.

[0078] The above-mentioned ultraviolet irradiation device, particularly the deep ultraviolet light emission device, can be widely used in various applications, such as water sterilization and purification devices for water purifiers, water coolers, water servers, medical-grade pure water, humidifiers, dishwashers, dental chairs, and more. [Examples]

[0079] The present invention will be further described below with reference to examples and comparative examples. The technical scope of the present invention is not limited thereto.

[0080] <Examples 1-3 and Comparative Example 1> (1) Preparation of addition-curing silicone rubber composition As an addition-curing silicone rubber composition, we prepared Silopren LSR7060 from Momentive Performance Materials (a silicone rubber composition comprising an organopolysiloxane having an average composition represented by formula (1), an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule, and a curing catalyst).

[0081] (2) Preparation of test specimens After curing the above silicone rubber composition in a mold, it was further cured in a constant temperature oven to produce a disc-shaped test piece with a thickness of 1 mm and a diameter of 30 mm made from the cured silicone rubber composition. The mold temperature, heating temperature in the constant temperature oven, and heating time will be described later. 13 The ratio of the area of ​​peak B to the sum of the areas of peak A appearing at 18.0–18.5 ppm and peak B appearing at 9.0–10.0 ppm in the C-MAS-NMR spectrum was adjusted to the values ​​shown in Table 1. Specifically, the material was heated in a mold at 120°C for 1 minute, and then cured by heating in a constant temperature oven at 140°C. In Comparative Example 1, heating in a constant temperature oven was not performed, in Comparative Example 2, the heating time in the constant temperature oven was 60 minutes, and in Examples 1 to 4, the heating time was between that of Comparative Example 1 and Comparative Example 2.

[0082] (3)Analysis (3.1) NMR measurement (Pre-processing) The central portion of the test specimen was taken and cut into 0.5-1.0 mm squares.

[0083] (measurement) Under the following conditions 13 C-MAS-NMR measurements were performed. (Measurement conditions) Equipment: Nuclear magnetic resonance Varian VNMRS-400 Observed nuclei: 13 C Observation frequency: 100.5MHz Measurement method: DDMAS Reference substance: Adamantane Pulse width: 2.7 μsec Waiting time: 15 seconds Total number of times: 5800 Rotation frequency (MAS rotation speed): 15kHz Sample temperature: 23℃ The NMR data processing, including the calculation of peak areas, was performed using Delta v6.0 from JEOL (Japan Electronics Co., Ltd.). Baseline correction was performed using the "Base Correct" function (automatic baseline correction) of the same software.

[0084] (3.2) ATR-FTIR measurement The central surface of the test specimen was subjected to ATR-FTIR infrared spectroscopy under the following conditions to obtain the absorption spectrum. (Measurement conditions) Equipment: Fourier transform infrared spectrophotometer (Agilent Cary 620 FTIR, manufactured by Agilent Technologies) Measurement method: Micro-ATR method ATR prism: Germanium (spherical) Refractive index 4.0 Incident angle: 30° Measurement area: 650~4000cm -1 Detector: MCT, High Sensitivity 100μm Number of reflections: 1 Resolution: 4cm -1 Total number of times: 128

[0085] Background measurements were performed in the same manner, except that the sample was not in contact with the prism. In addition, since the intensity of the absorption spectrum obtained in the ATR method changes depending on the degree of contact between the sample and the ATR prism, measurements were performed so that the maximum peak intensity was between 0.33 and 0.34.

[0086] (analysis) In the obtained absorption spectrum, at 1350 cm⁻¹ -1 and 926cm -1 These were defined as the starting points on the left and right sides of the baseline, respectively. And, 1013cm -1 Height h of the peak originating from the Si-O bond in the vicinity ref The result was calculated. Also, 2193cm -1 and 2080cm -1 After defining these as the starting points on the left and right sides of the baseline, respectively, 2138cm -1 Peak height h originating from nearby hydrosilyl groups SiH The result was calculated. The obtained values ​​were then applied to the following formula to calculate the concentration of the hydrosilyl group (SiH concentration). SiH concentration [mmol / g] = 30.2 × h SiH / h ref +0.021

[0087] (4) UV irradiation test (Fabrication of a light-emitting device) Using the obtained test specimens, a light-emitting device as shown in Figure 3 was fabricated. Specifically, a UVC-LED light source was placed at the bottom of the container as light source 1 that emits ultraviolet light, and the opening of the container was sealed with test specimen 2 to create the light-emitting device. Light source 1: UVC-LED light source (KL265-50W-SM-WD, manufactured by Crystal IS). It is driven at a constant current of 350mA, and the illuminance measured at 10mm directly above light source 1 using an ultraviolet illuminometer is 20mW / cm². 2 That's all. Distance d between the light-emitting surface of light source 1 and test piece 2: 1 mm

[0088] (UV irradiation test) Then, light with a central wavelength of 267 nm was irradiated from light source 1 (UVC-LED light source), and the irradiation time was determined to maintain a light transmittance of 88% or more at a wavelength of 265 nm. Light transmittance was measured using an ultraviolet-visible-near-infrared spectrophotometer over a 2 mm diameter area centered on the optical axis directly above light source 1.

[0089] Table 1 shows the evaluation results for Examples 1-4 and Comparative Examples 1-2. Also, for Example 4... 13 The main parts of the C-MAS-NMR spectra are shown in Figure 4. The ATR-FTIR absorption spectra for Examples 1-4 are shown in Figures 5A and 5B.

[0090] [Table 1]

[0091] As shown in Table 1, 13 In the C-MAS-NMR spectrum, the specimens of Examples 1 to 4, in which the ratio of the area of ​​peak B to the sum of the area of ​​peak A appearing at 18.0 to 18.5 ppm and the area of ​​peak B appearing at 9.0 to 10.0 ppm was between 31% and 68%, maintained a light transmittance of 88% or higher at a wavelength of 265 nm for an irradiation time of 400 hours or more. In contrast, the specimens of Comparative Example 2, which had a higher proportion of peak B area than 68%, or the specimens of Comparative Example 1, which had a lower proportion than 31%, required less than 400 hours of irradiation to maintain a light transmittance of 88% or higher at a wavelength of 265 nm. From these findings, it can be seen that if the area ratio of Peak B is between 31% and 68%, degradation due to deep ultraviolet light is minimal, and the element has high durability.

[0092] Furthermore, a comparison of Examples 1-4 with Comparative Examples 1 and 2 revealed that test specimens in which the concentration of hydrosilyl groups in the cured product, for which the absorption spectrum by ATR-FTIR was determined, was 0.20 mmol / g or more and 0.54 mmol / g or less, required an irradiation time of 400 hours or more to maintain a light transmittance of 88% or more at a wavelength of 265 nm. In contrast, the test specimens of Comparative Example 2, which had a hydrosilyl group concentration lower than 0.20 mmol / g, and the test specimens of Comparative Example 1, which had a concentration higher than 0.54 mmol / g, required irradiation times shorter than 400 hours to maintain a light transmittance of 88% or higher at a wavelength of 265 nm. These findings indicate that if the concentration of hydrosilyl groups in the cured product is between 0.20 mmol / g and 0.54 mmol / g, degradation due to deep ultraviolet light is minimal, resulting in high durability.

[0093] Furthermore, in the specimens of Examples 1 to 4, no peaks originating from vinyl groups were detected in the ATR-FTIR absorption spectrum, indicating that the concentration of vinyl groups was lower than in the specimen of Comparative Example 1. Consequently, the specimens of Examples 1 to 4 showed less yellowing and less degradation due to deep ultraviolet light than the specimen of Comparative Example 1. [Industrial applicability]

[0094] The cured product of the present invention exhibits minimal degradation from irradiation with deep ultraviolet light and possesses durability. Therefore, the cured product can be suitably used, for example, as an optical component in an ultraviolet irradiation device that uses a light source emitting ultraviolet light, particularly UVC. [Explanation of Symbols]

[0095] 1 light source 2 Test specimens 100 Ultraviolet irradiation device 110 circuit boards 120 Light sources that emit ultraviolet light 130 UV-transmitting window component 140 Resin adhesive layer 230 Light beam control member 231 Incidence plane 232 Ejection surface

Claims

1. A cured product of an addition-curing type silicone rubber composition, １３ In the C-MAS-NMR spectrum, the ratio of the area of ​​peak B to the sum of the area of ​​peak A appearing at 18.0–18.5 ppm and the area of ​​peak B appearing at 9.0–10.0 ppm is 31% or more and 68% or less. cured product.

2. A cured product of an addition-curing type silicone rubber composition, In the ATR-FTIR absorption spectrum, 2120–2180 cm⁻¹ －１ The concentration of hydrosilyl groups in the cured product, calculated from the peak derived from the hydrosilyl group appearing therein, is 0.20 mmol / g or more and 0.54 mmol / g or less. cured product.

3. In the ATR-FTIR absorption spectrum, 1630–1670 cm⁻¹ －１ The peak originating from the vinyl group that appears is undetectable. The cured product according to claim 1 or 2.

4. The aforementioned addition-curing type silicone rubber composition is (A) Organopolysiloxane having the average composition shown in formula (1), Equation (1): R １ ａ SiO （４－ａ）／２ (In the formula, R １ R is an alkenyl group, an alkyl group having 1 to 6 carbon atoms, an alkyl fluoride group having 1 to 6 carbon atoms, an aryl group, or a cycloalkyl group having 5 to 12 carbon atoms, and is contained in one molecule. １ (At least two of these are alkenyl groups, and a is a positive number between 1.95 and 2.05.) (B) Organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule, and (C) Curing catalyst including, The cured product according to claim 1 or 2.

5. A cured product comprising the product described in claim 1 or 2, Optical components for ultraviolet irradiation devices.

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