Silicone rubber composition and optical component for UV irradiation devices including the same

Abstract

To provide a silicone rubber composition capable of preventing discoloration or the like, even when paired with a light source that emits ultraviolet rays.SOLUTION: A silicone rubber composition includes (A) an organopolysiloxane having the average composition represented by formula (1): R1aSiO(4-a) / 2, containing at least two alkenyl groups in each molecule, (B) an organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in each molecule, and (C) a platinum complex catalyst containing an N-heterocyclic carbene ligand.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a silicone rubber composition and an optical part for an ultraviolet irradiation device using the same. [Background technology]

[0002] For example, ultraviolet irradiation devices that emit deep ultraviolet light in the short wavelength region of 210 to 310 nm are used in various devices for disinfection, sterilization, purification, and the like.

[0003] Fig. 1 is a schematic diagram showing an overview of an ultraviolet irradiation device 10 of Patent Document 1. As shown in Fig. 1, the ultraviolet irradiation device 10 has an LTCC substrate 11, a light source 12 that emits ultraviolet light, an ultraviolet transmission window member (quartz glass or the like) 13, a resin adhesive layer 14 arranged between the LTCC substrate 11 and the ultraviolet transmission window member (quartz glass or the like) 13, and a metal layer 15 arranged between the resin adhesive layer 14 and the ultraviolet transmission window member 13. For example, a silicone material or the like is used as the resin adhesive layer 14.

[0004] Known examples of silicone materials include addition curing reaction (hydrosilylation reaction) type compositions that contain an organopolysiloxane (base) having alkenyl groups, a crosslinking agent having hydrogen atoms bonded to silicon atoms, and a catalyst.

[0005] For example, Patent Document 2 discloses a silicone rubber composition containing (A) an organopolysiloxane having at least two alkenyl groups per molecule, (B) a silicone resin, (C) sol-gel silica, (D) a hydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms per molecule, and (E) a hydrosilylation catalyst. Known examples of the (E) hydrosilylation catalyst include platinum catalysts (such as chloroplatinic acid) and platinum complex catalysts (such as Karstedt's catalyst).

[0006] Such organic matter, such as silicone material, contained in the resin adhesive layer 14 is prone to deterioration (discoloration, etc.) when irradiated with UVC rays. Therefore, Patent Document 1 discloses that a metal layer 15 is provided as a light-shielding layer to suppress deterioration of the resin adhesive layer 14 when irradiated with UVC rays (see FIG. 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2017-147432 A [Patent Document 2] Patent Publication No. 2021-31543 Summary of the Invention [Problem to be solved by the invention]

[0008] However, providing the metal layer 15 in the above-described ultraviolet irradiation device 10 leads to increased costs. If a material capable of suppressing deterioration such as discoloration even when irradiated with UVC is used for the resin adhesive layer, there is no need to provide the metal layer 15. In addition, such a material can be cured and used in optical components such as the ultraviolet transmission window member 13 in place of quartz glass.

[0009] An object of the present invention is to provide a silicone rubber composition that can suppress the occurrence of discoloration and other problems even when irradiated with ultraviolet light, particularly UVC light, and an optical part for an ultraviolet irradiation device that uses the same. [Means for solving the problem]

[0010] [1] (A) an organopolysiloxane having an average composition represented by formula (1), Formula (1):R 1 a SiO (4-a) / 2 (In the formula, R 1is an alkenyl group, an alkyl group having 1 to 6 carbon atoms, a fluorinated alkyl group having 1 to 6 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms, and R 1 at least two of the groups are alkenyl groups, and a is a positive number of 1.95 to 2.05. (B) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in each molecule, and (C) Platinum complex catalysts with N-heterocyclic carbene ligands 1. A silicone rubber composition comprising: [2] The silicone rubber composition according to [1], wherein the platinum complex catalyst is a complex represented by formula (2): Formula (2) L1→Pt←L2 (In formula (2), L1 represents a ligand having a double bond; L2 represents a ligand represented by any one of the following formulas (I) to (III). [ka] (In formulas (I) to (III), A and B each represent a carbon atom (C) or a nitrogen atom (N), and when A and B each represent a nitrogen atom (N), -T3 and -T4 do not exist; T1 and T2 each represent an alkyl group, a cycloalkyl group, a fluoroalkyl group, an alkyl group substituted with a fluoroalkyl group, an arylalkyl group in which the aryl moiety may be substituted with an alkyl group or an alkoxy group, an aryl group, or a heteroaryl group; T3 to T8 each represent a hydrogen atom, a halogen atom, -NO2, -CN, -COOH, -CHO, -SO3H, -SO2-(C1-C8)alkyl, -SO-(C1-C8)alkyl, -NH-(C1-C8)alkyl, -N((C1-C8)alkyl)2, -NHCO-(C1-C4)alkyl, -CF3, -COO-(C1-C8)alkyl, -CONH2, -CO-(C1-C8)alkyl, -NHCOH, -NHCOO-(C1-C4)alkyl, CO-phenyl, -COO-phenyl, -CH=CH-CO2-(C1-C8)alkyl, -CH=CHCO2H, -PO(phenyl)2, -PO((C1-C8)alkyl)2, an optionally substituted alkyl group, an optionally substituted aryl group, or an optionally substituted heteroaryl group. [3] The silicone rubber composition according to [1] or [2], wherein the content of the platinum complex catalyst is 0.5 to 300 ppm by mass in terms of the amount of platinum atoms per 100 parts by mass of the combined total of the (A) component and the (B) component. [4] (D)R 2 SiO 3 / 2 Units and SiO 4 / 2 Units (R 2 The silicone rubber composition according to any one of [1] to [3], further comprising an organopolysiloxane resin containing at least one of the following: [5] The silicone rubber composition according to any one of [1] to [4], further comprising (E) silica particles. [6] The silicone rubber composition according to [5], wherein the (E) silica particles have been subjected to a hydrophobization treatment. [7] The silicone rubber composition according to any one of [1] to [6], wherein the viscosity of the component (A) at 25°C is 0.1 to 1000 Pa·s. [8] An optical part for an ultraviolet irradiation device, comprising a cured product of the silicone rubber composition according to any one of [1] to [7]. Effect of the Invention

[0011] According to the present invention, it is possible to provide a silicone rubber composition that can suppress the occurrence of discoloration and the like even when irradiated with ultraviolet light, particularly UVC light, and an optical part for an ultraviolet irradiation device using the same. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing an overview of an ultraviolet irradiation device according to Patent Document 1. As shown in FIG. [Diagram 2] FIG. 2 is a schematic diagram showing an ultraviolet irradiation device according to the present embodiment. [Diagram 3] FIG. 3A is a plan view of an ultraviolet irradiation device according to another embodiment, and FIG. 3B is a cross-sectional view taken along line BB in FIG. 3A. [Figure 4] FIG. 4 is a diagram showing a schematic configuration of the device used in the ultraviolet irradiation test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] As mentioned above, when a cured product of a conventional silicone rubber composition is irradiated with UVC, deterioration (discoloration) occurs. When UVC is irradiated, the Si-CH3 bond of dimethylpolysiloxane and the CH bond of -CH3 group, which may be contained in the cured product of the silicone rubber composition, are broken. As a result, discoloration, odorous substances such as formaldehyde, and shrinkage (cracks) due to unintended crosslinking are likely to occur.

[0014] The silicone rubber composition of the present invention contains a platinum complex catalyst having an N-heterocyclic carbene ligand as a hydrosilylation catalyst, which can suppress discoloration caused by UVC irradiation. That is, the platinum complex having an N-heterocyclic carbene ligand has an N-heterocyclic carbene ligand instead of at least a part of the tetramethyldivinyldisiloxane ligand in the conventional platinum complex catalyst (Karstedt catalyst, etc.). The N-heterocyclic carbene ligand has a stronger chelating effect with the platinum atom than the tetramethyldivinyldisiloxane ligand, and the coordinate bond to the platinum atom is less likely to break. Therefore, it is easy to maintain the state in which the periphery of the platinum atom is covered by the ligand. In addition, since the chelating effect between the ligand and the platinum atom is strong, it is less likely to be excited by UVC irradiation. As a result, it is considered that deterioration due to UVC irradiation can be suppressed. The configuration of the silicone rubber composition of the present invention will be described below.

[0015] 1. Silicone rubber composition The silicone rubber composition of the present invention comprises (A) an organopolysiloxane having at least two alkenyl groups per molecule, (B) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms per molecule, and (C) a platinum complex catalyst having an N-heterocyclic carbene ligand.

[0016] <Component (A)> Component (A) is the main component of the silicone rubber composition and is an organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule. The average composition of this organopolysiloxane is represented by formula (1). Formula (1): R 1 a SiO (4-a) / 2

[0017] R in Equation (1) 1 is an alkenyl group, an alkyl group having 1 to 6 carbon atoms, a fluorinated alkyl group having 1 to 6 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms. 1 At least two of these R are alkenyl groups. 1 is a substituent that does not absorb UVC light.

[0018] Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, and a hexenyl group, and the vinyl group is preferred. The alkenyl group may be present at the end of the molecular chain or in a side chain.

[0019] Examples of alkyl groups having 1 to 6 carbon atoms include methyl, ethylene, propyl, and butyl groups, and examples of fluorinated alkyl groups having 1 to 6 carbon atoms include these alkyl groups partially substituted with fluorine atoms. Examples of cycloalkyl groups having 5 to 12 carbon atoms include cyclohexyl and cyclohexenyl groups.

[0020] In formula (1), a is a positive number from 1.95 to 2.05.

[0021] The organopolysiloxane represented by formula (1) is preferably linear, and may partially contain a branched structure. That is, the organopolysiloxane represented by formula (1) preferably contains diorganosiloxane units (D units) as a main component. Specifically, the content of D units is preferably 90 mol% or more based on the total structural units (total siloxane units) of the organopolysiloxane. The type and amount of siloxane units can be identified by analysis using 29Si-NMR.

[0022] The organopolysiloxane represented by formula (1) is preferably a linear organopolysiloxane whose main chain contains diorganosiloxane units (D units) as the main component and whose molecular chain is terminated at both ends with triorganosiloxane units (M units). Of the R1 bonded to silicon atoms, the groups other than the alkenyl group preferably contain a methyl group. The alkenyl group is preferably a vinyl group.

[0023] From the viewpoint of further reducing molding defects such as flash, the viscosity of the organopolysiloxane represented by formula (1) at 25°C is preferably 0.1 Pa s or more, more preferably 0.5 Pa s or more, and even more preferably 1.0 Pa s or more. From the viewpoint of preventing the generation of bubbles and filling defects, the viscosity at 25°C is preferably 1000 Pa s or less, more preferably 800 Pa s or less, and even more preferably 600 Pa s or less.

[0024] Two or more organopolysiloxanes having different viscosities represented by formula (1) may be used in combination, so long as the viscosity of the mixture is within the above range.

[0025] The viscosity of component (A) can be measured at 25°C using a cone-plate rotational viscometer in accordance with JIS Z8803:2011.

[0026] The alkenyl group content of the organopolysiloxane represented by formula (1) is preferably 0.02 mmol / g or more, more preferably 0.05 mmol / g or more. When the alkenyl group content is 0.02 mmol / g or more, the crosslink density of the cured product is higher, so that the hardness property is more easily improved. The upper limit of the alkenyl group content is preferably less than 1.0 mmol / g, more preferably less than 0.8 mmol / g. When the alkenyl group content is less than 1.0 mmol / g, the crosslink density of the cured product is less likely to be excessively high, so that the breaking elongation of the cured product is less likely to be impaired, and the toughness is less likely to be impaired.

[0027] Two or more types of organopolysiloxanes represented by formula (1) having different alkenyl group contents may be used in combination, so long as the alkenyl group content of the mixture is within the above range.

[0028] The content of component (A) is preferably 40 to 98 mass % and more preferably 50 to 95 mass % of the silicone rubber composition. When the content of component (A) is at a certain level or more, it is easier to obtain a cured product with better moldability and appropriate hardness.

[0029] <(B) component> Component (B) functions as a crosslinking agent for component (A) and is an organohydrogenpolysiloxane that has at least two hydrogen atoms bonded to silicon atoms (-SiH) in each molecule.

[0030] 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, and preferably 4 to 200. The hydrogen atom bonded to the silicon atom may be at the end of the molecular chain or in a side chain.

[0031] 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, an alkyl group having 1 to 6 carbon atoms is preferred, and a methyl group is more preferred.

[0032] The content of hydrogen atoms bonded to silicon atoms in the organohydrogenpolysiloxane is not particularly limited as long as it is sufficient to react with the alkenyl groups of the component (A), but it is preferably 0.1 mmol / g to 20 mmol / g.

[0033] Examples of organohydrogenpolysiloxanes include diorganopolysiloxanes blocked with dimethylhydrogensilyl groups, copolymers containing dimethylsiloxane units, methylhydrogensiloxane units, and terminal trimethylsiloxy groups, copolymers containing dimethylhydrogensiloxane units and SiO 4 / 2 units (Q units), 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trihydrogen-1,3,5,7-tetramethylcyclotetrasiloxane, 1,5-dihydrogen-3,7-dihexyl-1,3,5,7-tetramethylcyclotetrasiloxane, and the like.

[0034] The content of the (B) component is not particularly limited as long as it is within a range that can sufficiently crosslink the (A) component. However, the number of moles of the hydrosilyl groups in the (B) component is preferably 0.8 to 5 moles, and more preferably 1 to 3 moles, per mole of the alkenyl groups in the (A) component.

[0035] <(C) component> Component (C) is a catalyst for promoting the hydrosilylation reaction between the alkenyl group of component (A) and the hydrogen atom bonded to the silicon atom of component (B), and is a platinum complex catalyst having an N-heterocyclic carbene ligand. The platinum complex catalyst is preferably a complex represented by the following formula (2). Formula (2) L1→Pt←L2

[0036] L1 in formula (2) represents a ligand having a double bond. The ligand having a double bond is preferably a compound having two double bonds (diolefin compound).

[0037] That is, the complex represented by formula (2) is preferably represented by formula (3). [ka]

[0038] X in formula (3) is O, NR a or CR f R g Y1 and Y2 are CR b R c or SiR d R e Shows.

[0039] R1, R2, R5 and R6 each represent a hydrogen atom, an alkyl group, or an aryl group which may be substituted with an alkyl group, and may be the same or different.

[0040] R3, R4, (NR a R a , (CR b R c Rb and R c respectively represent a hydrogen atom, an alkyl group, an acyl group, an aryl group which may be substituted with an alkyl group, a cycloalkyl group which may be substituted with an alkyl group, or an arylalkyl group in which the aryl moiety may be substituted with an alkyl group.

[0041] R d and R e respectively represent an alkenyl group, an alkynyl group, an alkyl group, an alkoxy group, an acyl group, an aryl group which may be substituted with an alkyl group, a cycloalkyl group which may be substituted with an alkyl group, or an arylalkyl group in which the aryl moiety may be substituted with an alkyl group. d R e In the case of d (or R e ) may be linked together to form a chain (a saturated hydrocarbon chain or a chain containing silicon atoms).

[0042] R f and R g respectively represent a hydrogen atom, an alkyl group, an acyl group, an aryl group which may be substituted with an alkyl group, a cycloalkyl group which may be substituted with an alkyl group, an arylalkyl group in which the aryl moiety may be substituted with an alkyl group, a halogen atom, an alkenyl group, or an alkynyl group.

[0043] In the above formula (3), the number of carbon atoms in the alkyl group is preferably 1 to 8, more preferably 1 to 7; the number of carbon atoms in the aryl group is preferably 6 to 18, more preferably 6 to 10. The number of carbon atoms in the alkenyl group is preferably 2 to 8, more preferably 2 to 6. The number of carbon atoms in the arylalkyl group is preferably 6 to 19, and includes a benzyl group, a trimethylphenyl group, and the like.

[0044] The cycloalkyl group may be a monocyclic cycloalkyl group or a polycyclic (preferably bicyclic) cycloalkyl group, and the number of carbon atoms therein is preferably 3 to 10. Examples of the polycyclic cycloalkyl group include an adamantyl group and a norbornenyl group, and examples of the monocyclic cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group.

[0045] Y1 and Y2 are both CR b R c or both are SiR d R e That is, the complex represented by formula (4) is preferably represented by formula (3-1) or (3-2), and more preferably represented by formula (3-3). [ka]

[0046] In formula (3-1) and formula (3-2), R 1 b and R 1 c , R 2 b and R 2 c is R in Eq. (3). b and R c and R 1 d and R 1 e , R 2 d and R 2 e is R in Eq. (3). d and R e Among them, R 1 b =R 2 b , R 1 c =R 2 c , R 1 d=R 2 d , R 1 e =R 2 e Preferably, R 3 =R 4 , R 5 =R 2 , R 1 =R 6 It is more preferable that:

[0047] [ka]

[0048] In formula (3-3), R3 represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 3 to 8 carbon atoms which may be substituted with an alkyl group having 1 to 4 carbon atoms. d and R e is R in Eq. (3). d and R e are synonymous with each other.

[0049] L2 in formula (2) is an N-heterocyclic carbene ligand. The N-heterocyclic carbene ligand is preferably represented by formula (I), (II) or (III). [ka]

[0050] In the above formula, A and B each represent a carbon atom (C) or a nitrogen atom (N), provided that when A and B each represent a nitrogen atom (N), -T3 and -T4 do not exist.

[0051] T1 and T2 in the above formula respectively represent an alkyl group, a cycloalkyl group, a fluorinated alkyl group, an alkyl group substituted with a fluorinated alkyl group, an arylalkyl group in which the aryl moiety may be substituted with an alkyl group or an alkoxy group, an aryl group, or a heteroaryl group. The alkyl group, cycloalkyl group, and arylalkyl group in the above formula respectively have the same meaning as the alkyl group, cycloalkyl group, and arylalkyl group in formula (3). These groups may further be substituted with a substituent. From the viewpoint of reducing UVC absorption and reducing coloring of the cured product of the silicone rubber composition, it is preferable that T1 and T2 in the above formula are an alkyl group, a cycloalkyl group, a fluorinated alkyl group, or an alkyl group substituted with a fluorinated alkyl group.

[0052] Fluorinated alkyl groups are -(CH2) p -C q F 2q+1 In the above structure, p is an integer of 0 to 4, q is an integer of 1 to 10, and C q F 2q+1 is linear or branched. Examples of groups having the above structure include -(CH2)2-(CF2)5-CF3, and -(CF2)7-CF3.

[0053] Among these, from the viewpoints of preventing clustering of platinum atoms and enhancing activity, T1 and T2 are preferably bulky groups, and are preferably cycloalkyl groups, secondary alkyl groups, tertiary alkyl groups, fluorinated alkyl groups having 4 or more carbon atoms, alkyl groups substituted with fluorinated alkyl groups, or aryl groups. From the viewpoints of not absorbing UVC and enhancing stability, cycloalkyl groups, secondary alkyl groups, tertiary alkyl groups, fluorinated alkyl groups having 4 or more carbon atoms, and alkyl groups substituted with fluorinated alkyl groups are more preferable, and a t-butyl group, a perfluoro-t-butyl group, an adamantyl group, or a cyclohexyl group is particularly preferable.

[0054] In the above formula, T3 to T8 respectively represent a hydrogen atom, a halogen atom, -NO2, -CN, -COOH, -CHO, -SO3H, -SO2-(C1-C8)alkyl, -SO-(C1-C8)alkyl, -NH-(C1-C8)alkyl, -N((C1-C8)alkyl)2, -NHCO-(C1-C4)alkyl, -CF3, -COO-(C1-C8)alkyl, -CONH2, -CO-(C1-C8)alkyl, -NHCOH, -NHCOO-(C1-C4)alkyl, -CO-phenyl, -COO-phenyl, -CH=CH-CO2-(C1-C8)alkyl, -CH=CHCO2H, -PO(phenyl)2, -PO((C1-C8)alkyl)2, an optionally substituted alkyl group, an optionally substituted aryl group, or an optionally substituted heteroaryl group. At least two of T3 to T8 may be bonded to each other to form a 4- to 12-membered ring. Among them, T3 to T8 are preferably hydrogen atoms.

[0055] Specific examples of the complex represented by formula (2) include the following. [ka]

[0056] From the viewpoint of sufficiently promoting the hydrosilylation reaction of components (A) and (B), the content of component (C) is preferably 0.5 ppm by mass or more, more preferably 1 ppm by mass or more, and most preferably 2 ppm by mass or more, in terms of the amount of platinum atoms, per 100 parts by mass of components (A) and (B) combined. Also, from the viewpoint of increasing the transmittance in the UVC wavelength region, the upper limit of the content of component (C) is preferably 300 ppm by mass or less, more preferably 200 ppm by mass or less, and most preferably 100 ppm by mass or less, in terms of the amount of platinum atoms, per 100 parts by mass of components (A) and (B) combined.

[0057] <Other ingredients> The silicone rubber composition of the present invention may further contain other components in addition to those described above, as necessary. Examples of the other components include (D) a silicone resin, (E) silica particles, (F) a hydrosilylation reaction inhibitor, etc.

[0058] (D) Ingredients: (D) component is R 2 SiO 3 / 2 Units (T units) and SiO 4 / 2 It is a silicone resin that contains at least one of the units (Q units) and has at least two alkenyl groups in one molecule. 2 is a monovalent hydrocarbon group having 1 to 6 carbon atoms. Such a silicone resin has a three-dimensional network structure, which can increase the hardness of the cured product of the silicone rubber composition. 2 At least two of the T and Q groups are preferably alkenyl groups. The total amount of T units and Q units may be 50 mol % or more based on the total structural units of the silicone resin.

[0059] Examples of the monovalent hydrocarbon group having 1 to 6 carbon atoms include an alkyl group, a cyclohexyl group, a cyclohexenyl group, and an alkenyl group. The alkyl group having 1 to 6 carbon atoms is preferably a methyl group. The alkenyl group is preferably a vinyl group.

[0060] Examples of such 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 Among them, silicone resins consisting of R units (T units) are included. 2 3SiO 1 / 2 Units (M units) and SiO 4 / 2 Silicone resins containing units (Q units) are preferred.

[0061] R 23SiO 1 / 2 Units (M units) and SiO 4 / 2 Silicone resins containing units (Q units) are R 2 2SiO 2 / 2 Units (D units) and R 2 SiO 3 / 2 In order to increase the hardness of the cured product, the total amount of M units and Q units in the silicone resin is preferably 80 mol % or more, and more preferably 90 mol % or more, based on the total amount of all structural units.

[0062] The ratio of M units to Q units is preferably 0.6 to 1.2 mol, more preferably 0.8 to 1.0 mol, of M units per mol of Q units. If the number of M units per mol of Q units is 0.6 mol or more, gelation is unlikely to occur, and if it is 1.2 mol or less, a three-dimensional network structure develops and sufficient hardness is easily obtained.

[0063] Examples of silicone resins 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.

[0064] The content of component (D) is, for example, 5 to 50 parts by mass per 100 parts by mass of component (A). When the content of component (D) is 5 parts by mass or more, the hardness of the cured product does not become too low, and when it is 50 parts by mass or less, the cured product does not become too brittle.

[0065] (E) Ingredients: The silica particles (E) can be added from the viewpoint of increasing the ultraviolet ray diffusion effect of the cured product and imparting sufficient tear strength and strength to the cured product. The type of silica particles (E) is not particularly limited, but from the viewpoint of not interfering with the function of the catalyst of the (C) component, gel method silica or fumed silica is preferred, and hydrophobically treated fumed silica particles are more preferred.

[0066] The hydrophobically treated silica particles may be silica particles surface-treated with a silane coupling agent, a silazane compound, or a low molecular weight siloxane compound having a hydrophobic group. Examples of the silazane compound include hexamethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, and the like. Examples of the low molecular weight siloxane compound include octamethylcyclotetrasiloxane, and the like. The silane coupling agent having a hydrophobic group has a hydrolyzable group and a hydrophobic group. Examples of the hydrolyzable group include an alkoxy group such as a methoxy group or an ethoxy group, a chloro group, or a silazane group, and the like. Examples of the hydrophobic group include an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, or an alkenyl group having 1 to 3 carbon atoms, and more preferably a methyl group and a vinyl group.

[0067] The hydrolyzable groups are hydrolyzed by water to become hydroxyl groups, which undergo a dehydration condensation reaction with the hydroxyl groups on the surface of the silica particles (E), imparting hydrophobic groups to the surfaces of the silica particles (E), thereby suppressing aggregation of the silica particles (E) and unintended effects on the (C) component, and improving the dispersibility of the silica particles.

[0068] The average primary particle size of the silica particles (E) is preferably 5 to 300 nm, more preferably 5 to 200 nm, and further preferably 5 to 100 nm. When the average primary particle size is 5 nm or more, the ultraviolet transmittance is less likely to be impaired due to aggregation of the silica particles, and when it is 300 nm or less, the ultraviolet diffusing effect is improved and a sufficient effect of improving mechanical strength is easily obtained.

[0069] The content of the silica particles (E) is preferably 1 to 20 parts by mass, and more preferably 2 to 10 parts by mass, per 100 parts by mass of the component (A). When the content of the silica particles (E) is 1 part by mass or more, a cured product having sufficient diffusion effect and mechanical strength is easily obtained, and when it is 20 parts by mass or less, the ultraviolet transmittance of the cured product is less likely to be impaired.

[0070] Reaction Inhibitors: The silicone rubber composition of the present invention may further contain a hydrosilylation reaction inhibitor from the viewpoint of ensuring pot life, etc. Examples of the hydrosilylation reaction inhibitor include polyfunctional alkenyl compounds such as 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, and acetylene alcohol derivatives such as 2-methyl-3-butyn-2-ol, 3-methyl-1-butyn-3-ol, and 3-methyl-1-pentyn-3-ol.

[0071] The content of the reaction inhibitor 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 the component (A).

[0072] <Preparation method> The silicone rubber composition of the present invention can be obtained by uniformly mixing the above-mentioned components using any mixing machine such as a kneader, a gate mixer, a Shinagawa mixer, a Henschel mixer, a pressure kneader, a three-roll mill, or a two-roll mill.

[0073] 2. Cured silicone rubber composition The cured product of the silicone rubber composition of the present invention can be obtained by heating and curing the silicone rubber composition at, for example, 80 to 250° C., and preferably 120 to 200° C. The heating time varies depending on the heating temperature, but can be, for example, 10 seconds to 120 minutes.

[0074] The cured product of the silicone rubber composition of the present invention, when cut into a 1 mm thick plate, preferably has a transmittance of 70% or more for light with a wavelength of 265 nm as measured by an ultraviolet-visible-near infrared spectrophotometer. Also, after being irradiated with light with a central wavelength of 265 nm from a position 1 mm away from a UVC-LED light source for 1000 hours, the transmittance of light with a central wavelength of 265 nm is preferably 60% or more.

[0075] A cured product of the silicone rubber composition can be obtained by a known molding method, such as injection molding, press molding, etc. Thereby, for example, a molded article can be obtained.

[0076] 3.Applications As described above, the cured product of the silicone rubber composition of the present invention has good durability against ultraviolet light. Therefore, the cured product of the silicone rubber composition of the present invention is suitable as an optical component, particularly an optical component used in an ultraviolet light irradiation device using a light source that emits ultraviolet light. The type of optical component used in the ultraviolet light irradiation device is not particularly limited, and can be, for example, a sealing member or adhesive member, a transparent member that transmits ultraviolet light, or an optical control member that controls the orientation of ultraviolet light. That is, the silicone rubber composition of the present invention is suitable as an adhesive, sealing, or molding material used in an ultraviolet light irradiation device.

[0077] An example of an ultraviolet irradiation device according to an embodiment of the present invention will be described below.

[0078] FIG. 2 is a schematic diagram showing an ultraviolet irradiation device 100 according to this embodiment.

[0079] 2, the ultraviolet irradiation device 100 has 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 a cured product of the silicone rubber composition.

[0080] The type of the substrate 110 is not particularly limited, and may be, for example, a multi-layer 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.

[0081] The light source 120 that emits ultraviolet light is mounted on the substrate 110. In this embodiment, the light source 120 is disposed in the recess 110a. The light source 120 that emits ultraviolet light is not particularly limited as long as it emits ultraviolet light, and examples thereof include a light-emitting diode (LED), a mercury lamp, a metal halide lamp, a xenon lamp, and a laser diode (LD). 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 that the desired effects such as sterilization efficiency are particularly easily obtained. In other words, the ultraviolet light is more preferably ultraviolet C wave (UVC).

[0082] The ultraviolet ray transmitting window member 130 is a member that transmits ultraviolet rays emitted from the light source 120. In this embodiment, the ultraviolet ray transmitting window member 130 is disposed so as to cover the recess 110a of the substrate 110 and to face the light emitting surface of the light source 120 in the recess 110a (see FIG. 2). The material constituting the ultraviolet ray transmitting window member 130 may be any material that transmits ultraviolet rays (particularly deep ultraviolet rays), and may be, for example, a cured product of the silicone rubber composition, quartz glass, sapphire, MgO, MgF2, CaF2, synthetic phased silica, or the like.

[0083] The resin adhesive layer 140 may be a sealing member disposed between the substrate 110 and the ultraviolet ray transmitting window member 130. In this embodiment, the material constituting the resin adhesive layer 140 is not particularly limited, and may be a cured product of the above-mentioned silicone rubber composition, an acrylic resin, an epoxy resin, a silicone resin, an organic / inorganic (e.g., silicone / silica) hybrid resin, a fluorine-based resin, or the like.

[0084] When the cured product of the silicone rubber composition is used as the resin adhesive layer 140, it is preferable that the number of moles of hydrosilyl groups / the number of moles of alkenyl groups in the silicone rubber composition is greater than 2. It is also preferable that the silicone compounds such as the component (A), the component (B) and the silicone resin (D) contained in the silicone rubber composition have functional groups that can react with the objects to be bonded (the functional groups on the surfaces of the substrate 110 and the ultraviolet transmitting window member 130 in this embodiment). Within the range of the content described in the present invention, the viscosity of the silicone rubber composition may be appropriately adjusted to be lower than the viscosity shown in the examples described later, or the catalyst concentration may be adjusted to be higher than the catalyst concentration shown in the examples described later.

[0085] The distance d between the ultraviolet ray 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 may be, for example, 0.1 to 10 mm, and preferably 0.5 to 5 mm (see FIG. 2). Here, the "optical axis LA of the light source 120" refers to the central light ray of the three-dimensional emitted light flux from the light source 120.

[0086] According to the ultraviolet irradiation device 100 of the above embodiment, at least one of the ultraviolet transmission window member 130 and the resin adhesive layer 140 contains a cured product of the silicone rubber composition. Therefore, these optical components are less likely to deteriorate, such as discolored, even if they are irradiated with ultraviolet rays (e.g., UVC) for a long period of time.

[0087] 2 as an ultraviolet irradiation device in the above embodiment, but is not limited thereto and may be any device having a light source that emits ultraviolet rays. That is, the optical components for the ultraviolet irradiation device are not limited to the ultraviolet transmission window member 130 and the resin adhesive layer 140, but may be any components that are required to suppress deterioration such as discoloration due to ultraviolet rays.

[0088] For example, the cured product of the silicone rubber composition may be used as an optical control member that controls the orientation of ultraviolet light. Examples of such optical control members include, but are not limited to, a condenser lens, a diffusing lens, a total reflection lens, and a hemispherical lens for controlling the distribution of ultraviolet light emitted from a light source.

[0089] Figures 3A and 3B are diagrams showing the configuration of an ultraviolet irradiation device 100 according to another embodiment. Figure 3A is a plan view, and Figure 3B is a cross-sectional view taken along line BB in Figure 3A. Note that the same or similar members as those in Figure 2 are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0090] As shown in FIG. 3B, ultraviolet irradiation device 100 has substrate 110, light source 120 that emits ultraviolet light, and light flux controlling member 230 (optical component) arranged on light source 120.

[0091] Light flux controlling member 230 is a member that controls the light distribution of ultraviolet light emitted from light source 120 that emits ultraviolet light, and is arranged facing the light emitting surface of light source 120 (see FIG. 3B). Light flux controlling member 230 has incident surface 231 and exit surface 232. In the present embodiment, incident surface 231 and exit surface 232 are rotationally symmetric with respect to central axis CA of light flux controlling member 230. Light flux controlling member 230 can be arranged on light source 120 such that central axis CA of light flux controlling member 230 coincides with optical axis LA of light source 120. Distance d between incident surface 231 and the light emitting surface of light source 120 on optical axis LA of light source 120 can also be similar to that described above.

[0092] In this way, an optical component including a cured product of the silicone rubber composition is also suitable as an optical control member that controls the orientation of ultraviolet light in the ultraviolet irradiation device 100.

[0093] The above-mentioned ultraviolet irradiation device, particularly the deep ultraviolet light emitting device, can be widely used for various applications, such as water sterilization and purification devices for water purifiers, water coolers, water servers, medical pure water, humidifiers, dishwashers, dental chairs, etc. EXAMPLES

[0094] The present invention will be further described below with reference to examples and comparative examples, but the technical scope of the present invention is not limited thereto.

[0095] 1.Material <Component (A)> A-1: Poly(dimethyl-methylvinyl)siloxane with dimethylvinylsiloxy groups at both ends (viscosity at 25°C: 1 Pa·s, number average degree of polymerization: 300-400, vinyl group content: 0.08 mmol / g) A-2: Poly(dimethyl-methylvinyl)siloxane with dimethylvinylsiloxy groups at both ends (viscosity at 25°C: 60 Pa·s, number average degree of polymerization: 1500-1600, vinyl group content: 0.02 mmol / g)

[0096] <(B) component> B: Poly(dimethyl-methylhydrogen)siloxane with trimethylsiloxy groups at both ends (viscosity at 25°C: 0.15 Pa·s, hydrogen content (-SiH group content): 0.38 mmol / g)

[0097] The viscosities of A-1, A-2 and B were measured at 25°C using a cone-plate rotational viscometer in accordance with JIS Z8803:2011.

[0098] <(C) component> As platinum complex catalysts having an N-heterocyclic carbene ligand, C-1 to C-5 were prepared. [ka]

[0099] For comparison, c-1 (Karstedt catalyst; platinum-alkenylsiloxane complex) was prepared. [ka]

[0100] 2. Preparation and Evaluation of Silicone Rubber Compositions <Example 1> A silicone rubber composition was prepared by mixing (A) 100 parts by mass of the above dimethylpolysiloxane (A-1), (B) 32 parts by mass of the above methylhydrogenpolysiloxane, (C) 10 ppm by mass of the above catalyst (C-1) in terms of platinum atomic weight, and 0.01 part by mass of 2-methyl-3-butyn-2-ol as an inhibitor, using a Henschel mixer.

[0101] <Examples 2 to 20, Comparative Examples 1 to 2> A silicone rubber composition was prepared in the same manner as in Example 1, except that the composition was changed to that shown in Table 1 or Table 2.

[0102] <Evaluation> Test pieces containing the resulting cured silicone rubber composition were prepared and subjected to accelerated irradiation testing.

[0103] (Preparation of test specimens) The obtained silicone rubber composition was placed in a mold at room temperature and 170°C (120°C when Karstedt catalyst was used) and cured for 30 minutes, and then further post-cured in a thermostatic oven at 150°C for 2 hours to prepare a plate-shaped test specimen with a thickness of 1 mm.

[0104] (Fabrication of light-emitting device) Using the obtained test piece, a light-emitting device 1 as shown in Fig. 4 was produced. Specifically, a UVC-LED light source was placed at the bottom of a container as light source 1 for emitting ultraviolet light, and the opening of the container was blocked with test piece 2 to produce a light-emitting device. Light source 1: UVC-LED light source (KL265-50W-SM-WD, manufactured by Crystal IS) (Operated at a constant current of 350mA, the illuminance measured at 10mm directly above the light source 1 by the UV illuminometer was 20mW / cm 2 That's it.) Distance d between the light emitting surface of the light source 1 and the test piece 2: 1 mm

[0105] (UV irradiation test) The appearance was visually observed before, after 500 hours of irradiation, and after 1000 hours of irradiation with UVC containing light with a wavelength of 260 to 270 nm from light source 1 (UVC-LED light source). If the appearance after 1000 hours of irradiation was transparent to light brown, it was judged as good, and if it was brown, it was judged as bad. In addition, the light transmittance at a wavelength of 265 nm was measured using an ultraviolet-visible-near infrared spectrophotometer before, after 500 hours of irradiation, and after 1000 hours of irradiation with UVC from the light source 1. The appearance and light transmittance were measured in an area directly above the light source 1, with a diameter of 2 mm centered on the optical axis.

[0106] The evaluation results of Examples 1 to 10 and Comparative Examples 1 and 2 are shown in Table 1, and the evaluation results of Examples 11 to 20 are shown in Table 2. Note that, for the catalyst of component (C) only, the unit is not parts by mass, but the amount of platinum atoms per 100 parts by mass of the total of components (A) and (B) is shown in ppm by mass.

[0107] [Table 1]

[0108] [Table 2]

[0109] As shown in Tables 1 and 2, the test pieces of Examples 1 to 20, which used platinum complex catalysts (C-1) to (C-5) having an N-heterocyclic carbene ligand as a hydrosilylation catalyst, maintained their transparency even after the accelerated irradiation test, and the decrease in light transmittance was also suppressed.

[0110] In particular, it can be seen that by using platinum complex catalysts (C-1) to (C-3) in which T1 and T2 in formula (I) or (III) are a cyclohexyl group or a t-butyl group, the decrease in light transmittance is less and transparency is more easily maintained (for example, comparison between Examples 1 to 3 and Examples 4 to 5).

[0111] In contrast, the test pieces of Comparative Examples 1 and 2, which used the conventional catalyst (c-1) as the hydrosilylation catalyst, showed a brown appearance after the accelerated irradiation test and a large decrease in light transmittance. [Industrial Applicability]

[0112] A cured product of the silicone rubber composition according to the present invention can be used, for example, in optical parts for an ultraviolet irradiation device that irradiates a light source that emits ultraviolet light, particularly UVC light. [Explanation of symbols]

[0113] 10, 100 UV irradiation device 11, 110 board 12, 120 Light source emitting ultraviolet light 13, 130 UV-transmitting window material 14, 140 Resin adhesive layer 15 metal layer 230 Light flux control member 231 Incidence plane 232 Exit surface

Claims

1. (A) an organopolysiloxane having an average composition represented by formula (1), Formula (1): R １ ａ SiO （４－ａ）／２ (In the formula, R １ is an alkenyl group, an alkyl group having 1 to 6 carbon atoms, a fluorinated alkyl group having 1 to 6 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms, and R １ at least two of the groups are alkenyl groups, and a is a positive number of 1.95 to 2.

05. (B) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in each molecule, and (C) Platinum complex catalyst having an N-heterocyclic carbene ligand Including, Silicone rubber composition.

2. The platinum complex catalyst is a complex represented by formula (2): The silicone rubber composition according to claim 1. Formula (2) L １ →Pt←L ２ (In formula (2), L １ represents a ligand having a double bond, L ２ represents a ligand represented by any one of the following formulas (I) to (III): 【Chemical 1】 (In formulas (I) to (III), A and B each represent a carbon atom (C) or a nitrogen atom (N), and when A and B each represent a nitrogen atom (N), -T ３ and -T ４ does not exist, T １ and T ２ respectively represent an alkyl group, a cycloalkyl group, a fluoroalkyl group, an alkyl group substituted with a fluoroalkyl group, an arylalkyl group in which the aryl moiety may be substituted with an alkyl group or an alkoxy group, an aryl group, or a heteroaryl group; T ３ ~T ８ are hydrogen atoms, halogen atoms, and -NO ２ , -CN, -COOH, -CHO, -SO ３ H, -SO ２ -(C1-C8) alkyl, -SO-(C1-C8) alkyl, -NH-(C1-C8) alkyl, -N((C1-C8) alkyl) ２ , —NHCO—(C1-C4)alkyl, —CF ３ , —COO—(C1-C8)alkyl, —CONH ２ , —CO—(C1-C8)alkyl, —NHCOH, —NHCOO—(C1-C4)alkyl, CO-phenyl, —COO-phenyl, —CH═CH—CO ２ -(C1-C8) alkyl, -CH=CHCO ２ H, -PO(phenyl) ２ , —PO((C1-C8) alkyl) ２ , an optionally substituted alkyl group, an optionally substituted aryl group, or an optionally substituted heteroaryl group)

3. The content of the platinum complex catalyst is 0.5 to 300 ppm by mass in terms of the amount of platinum atoms relative to 100 parts by mass of the total of the component (A) and the component (B). The silicone rubber composition according to claim 1.

4. (D)R ２ SiO ３／２ Units and SiO ４／２ Unit (R ２ is a monovalent hydrocarbon group having 1 to 6 carbon atoms), and further includes an organopolysiloxane resin containing at least two alkenyl groups per molecule. The silicone rubber composition according to claim 1.

5. (E) further comprising silica particles; The silicone rubber composition according to claim 1.

6. The (E) silica particles have been subjected to a hydrophobic treatment. The silicone rubber composition according to claim 5.

7. The viscosity of the component (A) at 25°C is 0.1 to 1000 Pa s. The silicone rubber composition according to claim 1.

8. A cured product of the silicone rubber composition according to claim 1. Optical components for ultraviolet irradiation equipment.

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