JP2007031619A - Resin composition for optical element sealing use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for optical element sealing use excellent in transparency and UV resistance and also resistance to heat discoloration. <P>SOLUTION: The resin composition for optical element sealing use comprises, as resin components, (A) a liquid silsesquioxane with a cage structure containing carbon-carbon unsaturated bonds, represented by formula (I): (R1-SiO<SB>3/2</SB>)<SB>a-n</SB>(X1-SiO<SB>3/2</SB>)<SB>n</SB>(wherein, R1 is a carbon-carbon unsaturated bond-containing hydrocarbon group or silyloxy group; X1 is a monovalent organic group free of both H-Si bond and carbon-carbon unsaturated bond; (a) is an even number of 6-14; and n is a positive integer smaller than (a)) and (B) a second liquid silsesquioxane with a cage structure containing H-Si bonds, represented by the formula (II): (R2-SiO<SB>3/2</SB>)<SB>a-n</SB>(X2-SiO<SB>3/2</SB>)<SB>n</SB>(wherein, R2 is H or a H-Si bond-containing monovalent organic group; X2 is a monovalent organic group free of both H-Si bond and carbon-carbon unsaturated bond; and (a) and n are each the same as mentioned above). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a resin composition for encapsulating an optical element, and more specifically, an optical element encapsulating mainly composed of a curable silsesquioxane having excellent transparency and UV resistance and excellent heat-resistant colorability. The present invention relates to a stopping resin composition.

  Optical elements include various lasers (especially semiconductor lasers) and light-emitting elements such as light-emitting diodes (LEDs), light-receiving elements, composite optical elements, and optical integrated circuits. A sealing resin composition is used for these optical elements. ing. In recent years, light emitting devices having a short peak emission wavelength have been developed, and green to blue light emitting devices (LEDs, etc.) have been widely used. Technological development has been made to suit. Recently, there has been a dramatic increase in the brightness of light emitting elements having a short peak wavelength of light emission, and along with this, the amount of heat generated by optical elements, for example, light emitting electronic devices, tends to increase further. The performance required for the sealing resin is higher in terms of UV resistance, heat resistance, and the like.

Conventionally, a transparent epoxy resin has been frequently used as a sealing resin for an optical element such as an LED, but it has a high heat resistance but a low UV resistance, and is easily yellowed over time. Since yellowing causes a decrease in luminance of the optical element, it is difficult to apply an epoxy resin as a sealing material for an optical element whose luminance is increasing. In order to overcome the drawbacks of this epoxy resin, a sealing material for optical elements made of silsesquioxane containing a substituent such as an epoxy ring has been proposed (for example, see Patent Document 1).
JP 2004-359933 A

  However, in an acid anhydride curing system that is often used as an epoxy ring curing system, the curing accelerator may be a cause of coloration by heat. Therefore, development of a sealing resin composition using silsesquioxane having a curing system that does not use an epoxy ring is desired. However, in general, a platinum catalyst is often used for producing a silsesquioxane derivative, and it is also known that this platinum causes thermal coloring of a cured product.

  In view of the above-described present situation, an object of the present invention is to provide a resin composition for sealing an optical element which is excellent in transparency and UV resistance and excellent in heat-resistant coloring.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a sealing resin having a silsesquioxane derivative having a specific type of side chain introduced as a resin component has excellent heat-resistant coloring properties. The present invention has been completed based on the findings. That is, the present invention provides the following general formula (I):
_{(R1-SiO 3/2) a-} n (X1-SiO 3/2) n (I)
(In the formula, R1 is a hydrocarbon group having 2 to 12 carbon atoms (including carbon in the aliphatic carbon-carbon unsaturated bond) containing an aliphatic carbon-carbon unsaturated bond, or aliphatic. A silyloxy group containing a carbon-carbon unsaturated bond and no H-Si bond, and when there are a plurality of R 1 s, they may be the same or different, and X 1 is an H-Si bond and an aliphatic carbon- It is a monovalent organic group containing no carbon unsaturated bond, provided that X1 is not a hydrogen atom, and when there are a plurality of X1, they may be the same or different, and a is an even number of 6 to 14. N is a positive integer smaller than a.) Liquid silsesquioxane (A) having a cage structure containing an aliphatic carbon-carbon unsaturated bond and no H-Si bond And the following general formula (II):
(R2-SiO3 _{/ 2} ) _a-n (X2-SiO3 _{/ 2} ) _n (II)
(In the formula, R2 represents a hydrogen atom or a monovalent organic group containing an H-Si bond and no aliphatic carbon-carbon unsaturated bond. X2 is a monovalent organic group that does not contain an H-Si bond and an aliphatic carbon-carbon unsaturated bond, provided that X2 is not a hydrogen atom. A may be the same or different, a is an even number from 6 to 14. n is a positive integer smaller than a and contains an H—Si bond and is aliphatic carbon-carbon unsaturated. A resin composition for encapsulating an optical element comprising, as a resin component, at least one kind of silsesquioxane selected from the group consisting of a liquid silsesquioxane (B) having a saddle type structure that does not contain a bond.
The present invention is also an optical element that is sealed with the sealing resin composition.

(1) Since the sealing resin composition of the present invention can be crosslinked by a hydrosilylation reaction with the above-described configuration, the phenomenon of thermal coloring due to the use of a curing agent or a curing accelerator can be avoided.
(2) With the above-described configuration, the sealing resin composition of the present invention can prevent thermal coloring even if it is a silsesquioxane derivative containing platinum due to remaining in the manufacturing process.
(3) The sealing resin composition of the present invention is a silsesquioxane derivative containing a carbon-carbon unsaturated bond and / or a silsesquioxane derivative containing an H-Si bond in a liquid state in the above-described configuration. A curing system for hydrosilylation reaction can be constructed.
(4) The sealing resin composition of the present invention has the necessary performance required for a sealing material for high-brightness optical elements, having transparency, heat resistance, UV resistance, and heat-resistant coloration due to the above-described configuration. Each can be satisfied at a sufficient level.

  The resin composition for sealing an optical element of the present invention contains at least one silsesquioxane selected from the group consisting of the silsesquioxane (A) and the silsesquioxane (B) as a resin component. . In the silsesquioxane (A) in the present invention, in the general formula (I), R1 is an aliphatic carbon-carbon unsaturated bond (aliphatic carbon-carbon double bond or aliphatic carbon-carbon triple bond). ) (Hereinafter simply referred to as a carbon-carbon unsaturated bond) hydrocarbon group having 2 to 12 carbon atoms (including carbon in the carbon-carbon unsaturated bond) or carbon-carbon unsaturated group. It is a silyloxy group containing a saturated bond and no H-Si bond. When there are a plurality of R1, they may be the same or different.

  Examples of the C2-C12 hydrocarbon group containing the carbon-carbon unsaturated bond include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s- or t-butyl, pentyl, isopentyl, neopentyl, and octyl. , An alkyl group such as isooctyl, decyl and the like containing a carbon-carbon unsaturated bond such as vinyl, ethynyl, etc. as a substituent (eg, allyl, 1-propenyl, isopropenyl, etc.); vinyl, 1-butenyl, Unsaturated aliphatic hydrocarbon groups such as 2-butenyl and 2-pentenyl; unsaturated alicyclic hydrocarbon groups containing a carbon-carbon unsaturated bond such as 3-cyclohexenyl, 5-bicycloheptenyl and cyclopentenyl; styryl; An aliphatic unsaturated bond-containing aromatic hydrocarbon group such as cinnamyl can be exemplified. Of these, those having 2 to 8 carbon atoms are preferred, and those having 2 to 6 carbon atoms are more preferred. Among them, a group represented by CH2 = CH- (CH2) n- (where n is an integer of 1 to 8) (for example, vinyl, allyl, 3-butenyl, etc.), 3-cyclohexenyl, 5 -Bicycloheptenyl, cyclopentenyl, 5-hexenyl and the like are preferable.

  In order to introduce the hydrocarbon group having 2 to 12 carbon atoms containing the carbon-carbon unsaturated bond, for example, a silsesquioxane having a cage structure using a trifunctional organosilicon monomer having the hydrocarbon group is used. And a method of reacting a hydrogen atom bonded to Si in a silsesquioxane having a cage structure with a divinyl compound, a trivinyl compound, or the like. Note that the skeleton structure of the silsesquioxane having a cage structure can be synthesized by various methods. For example, the method described in JP-A-2004-359933 can be applied.

  Examples of the silyloxy group containing a carbon-carbon unsaturated bond and not containing an H-Si bond include dimethylvinylsilyloxy group, allyldimethylsilyloxy group, CH2 = CH- (CH2) 4-Si (Me) 2 -O-, 3-cyclohexenyl dimethylsilyloxy group, etc. are mentioned.

In order to introduce a silyloxy group containing the carbon-carbon unsaturated bond and not containing an H-Si bond, for example, a trifunctional organosilicon monomer having the silyloxy group is used to form a silsesquioxane having a cage structure. method for producing, ^{R4 N} + (R is a monovalent organic group) silicate cage structure having as a counter cation ^{_{((Si 8 O 20) 8-}} · 8R 4 N +) with respect dimethylsilyl chloride (HSi (Me ) 2Cl) and the like can be introduced by desalting reaction.

  In the said silsesquioxane (A) in this invention, in said general formula (I), X1 is a monovalent organic group which does not contain a H-Si bond and a carbon-carbon unsaturated bond. However, X1 is not a hydrogen atom. When there are a plurality of X1, they may be the same or different.

  Examples of the monovalent organic group that does not contain the H-Si bond and the carbon-carbon unsaturated bond include, for example, a hydrocarbon group having 1 to 20 carbon atoms that does not contain a carbon-carbon unsaturated bond (for example, methyl, Isobutyl, octyl, phenyl, benzyl, tolyl, xylyl, cumenyl, cyclohexyl, adamantyl, etc.), a C1-C20 hydrocarbon group containing a functional group other than a carbon-carbon unsaturated bond (for example, 3-hydroxypropyl, γ-glycidoxypropyl, 2-methoxysilylethyl, 2-triethoxysilylethyl, etc.), alkyl-substituted organosiloxyethyl groups (for example, heptamethyltrisiloxyethyl group, butyldimethylsilylethyl group, poly (dimethylsiloxy) ethyl) Group, etc.).

  In order to introduce the monovalent organic group not containing the H-Si bond and the carbon-carbon unsaturated bond, for example, a silsesquioxane derivative containing a vinyl group as a substituent is used as a raw material, and heptamethyltrisiloxane is used. A method such as hydrosilylation reaction of an alkyl-substituted organosiloxane having an H—Si bond such as can be employed.

  In the said silsesquioxane (A), a is an even number of 6-14 in the said general formula (I). n is a positive integer smaller than a. The silsesquioxane (A) in which a is 6 has a triangular prism type structural formula, the one in which a is 8 has a hexahedral structural formula, and the one in which a has 10 has a pentagonal structural formula. , A having 12 has an octahedral structure composed of four sides of a quadrangle and four sides of pentagon, and those having a of 14 have a nine-sided structure having a shape of three sides of a quadrangle and six sides of a pentagon. Has the formula Preferably a is 8, 10 or 12, more preferably a is 8. n is a positive integer smaller than a, and is therefore an integer within a range of 1 or more and 1 smaller than a. Preferably, it is an integer that is 2 or more and 2 smaller than a, more preferably an integer that is 3 or more and 3 smaller than a.

  In the present invention, the silsesquioxane (A) needs to satisfy the above conditions and be in a liquid state. Generally, in a silsesquioxane having a cage structure, it is usually solid when all hydrogen atoms on Si are substituted with no substituents or relatively small identical substituents. It is known from a phenomenon that when a group is introduced, a solid becomes a liquid. For example, in a silsesquioxane having a cage structure in which a is 8, if all the substituents are vinyl or have no substituents, they are solid, but other types of substituents are partially When it introduce | transduces, it will become solid-clay-like-high-viscosity liquid-low-viscosity liquid as the site | parts introduce | transduced to 1-5 among eight substitutable sites. The silsesquioxane (A) is preferably liquid at room temperature. From this viewpoint, when a is 8, n is preferably 3 to 5.

  Specific examples of the silsesquioxane (A) include, for example, R1 is a vinyldimethylsiloxy group, X1 is a heptamethyltrisiloxy group, a is 8, n is 3-5; R1 is vinyldimethylsiloxy Group, X1 is a poly (dimethylsiloxy) ethyl group, a is 8, n is 3-5, and the like.

  In the present invention, as the silsesquioxane (A), one or more of the above-mentioned ones, for example, those having different numbers of a, those having the same number of a but different numbers of n, Different types of groups that do not contain a functional group can be used in combination. Preferably, the number of a is the same compound.

  In the silsesquioxane (B) in the present invention, in the general formula (II), R2 represents a hydrogen atom or a monovalent that does not contain a carbon-carbon unsaturated bond. Represents an organic group. When there are a plurality of R2, they may be the same or different.

  Examples of the monovalent organic group containing an H—Si bond and not containing a carbon-carbon unsaturated bond include a group represented by H—Si (Me) 2 —O— (where Me represents a methyl group). And a group represented by H—Si (Me) 2 OSi (Me) 2 O—, and the like.

In order to introduce the monovalent organic group containing the H-Si bond and not containing the carbon-carbon unsaturated bond, for example, a method of producing silsesquioxane using trichlorosilane, R4N ⁺ (R is 1 And a method of introducing dimethylsilyl chloride (HSi (Me) 2Cl) or the like by desalting a silicate having a valent organic group) as a counter cation.

  In the silsesquioxane (B) in the present invention, in the general formula (II), X2 is a monovalent organic group not containing an H-Si bond and a carbon-carbon unsaturated bond. When there are a plurality of X2, they may be the same or different. However, X2 is not a hydrogen atom.

  Examples of the monovalent organic group not containing the H—Si bond and the carbon-carbon unsaturated bond in X2 include the monovalent organic groups exemplified for X1. Further, for example, hexyl, phenethyl, dodecyl, a group represented by (Me) 3-Si-O-Si (Me) 2-O-Si (Me) 2-CH2-CH2-, and the like may be used.

  In order to introduce a monovalent organic group that does not contain the above functional group, for example, a method such as reacting an unsaturated bond-containing hydrocarbon with a hydrogen atom bonded to a Si atom of silsesquioxane is employed. Can do.

  In the said silsesquioxane (B) in this invention, a is an even number of 6-14 in the said general formula (II). n is a positive integer smaller than a. About a and n, the above-mentioned description regarding the said silsesquioxane (A) corresponds.

  In addition, the silsesquioxane (B) needs to satisfy the above-described conditions and be in a liquid state, and the above-described explanation regarding the silsesquioxane (A) also applies to this.

  Specific examples of the silsesquioxane (B) include those in which R2 is an H-Si (Me) 2- group, X2 is a heptamethyltrisiloxy group, a is 8, and n is 3-5; R2 is a H-Si (Me) 2- group, X2 is a phenethyl group, a is 8, n is 3-5, and the like.

  In the present invention, as the silsesquioxane (B), one or more of the above-mentioned ones, for example, those having different numbers of a, those having the same number of a but different numbers of n, Different types of groups that do not contain a functional group can be used in combination. Preferably, the number of a is the same compound.

  In the present invention, the combination of the silsesquioxane (A) and the silsesquioxane (B) preferably has a structural formula in which a is 8, 10 or 12, and a is 8 It is more preferable to have a hexahedral structural formula. Further, in both cases, it is more preferable that a is 8 and n is 3 to 5.

  In the encapsulating resin composition of the present invention, the silsesquioxane (A) and the silsesquioxane (B) have a number of moles of H-Si bonds of 0.1 mole per mole of carbon-carbon unsaturated bonds. It is preferable to mix | blend in the ratio of 8-1.3, and 0.90-0.99 are more preferable.

  In the encapsulating resin composition of the present invention, the combination of the silsesquioxane (A) and the silsesquioxane (B) can be cured by forming a crosslinked product by a hydrosilylation reaction. There is no particular need to use the agent. When this curing proceeds in an autocatalytic manner, the reaction proceeds without adding a catalyst. In this case, low temperature storage is preferred from the viewpoint of storage stability. On the other hand, a catalyst can be used to accelerate the crosslinking reaction. As such a catalyst, for example, a platinum-based catalyst (for example, chloroplatinic acid hexahydrate (H2PtCl6 · 6H2O), divinyltetramethyldisiloxane · Pt complex, etc.) can be used.

  The blending amount of the catalyst is preferably 0.0001 to 0.05 parts by weight with respect to a total of 100 parts by weight of the silsesquioxane (A) and silsesquioxane (B), and 0.001 to 0. 0.001 part by weight is more preferred.

  In addition to the combination of the silsesquioxane (A) and the silsesquioxane (B) as the resin component, the resin composition of the present invention may contain only the silsesquioxane (A) or the silsesquioxane. Only Sun (B) may be used. In this case, it is preferable to add a crosslinking agent capable of crosslinking by a hydrosilylation reaction.

  For example, as a crosslinking agent combined with the silsesquioxane (A), for example, a compound having a plurality of H—Si bonds, for example, dimethylpolysiloxane represented by the following formula can be exemplified. In the formula, n is an integer of 0 or more, m is an integer of 2 or more, and n + m is 2 or more and 100 or less.

  Moreover, as a crosslinking agent combined with the said silsesquioxane (B), for example, a compound having a plurality of carbon-carbon unsaturated bonds, for example, 1,4-diethynylbenzene, B-triethynyl-N-trimethylborazine, Examples include triallyl isocyanurate, triallyl cyanurate, trimethallyl isocyanurate, and dimethylpolysiloxane having a vinyl group represented by the following formula. In the formula, n is an integer of 0 or more, m is an integer of 2 or more, and n + m is 2 or more and 100 or less.

  The amount of the crosslinking agent varies depending on the compound used. For example, in the case of the compound represented by the above formula, the silsesquioxane (A) or the silsesquioxane (B) is used. 1 to 80 mol% is preferable, and 2 to 60 mol% is more preferable.

  Moreover, you may use a catalyst and can use the above-mentioned as this catalyst. The amount used can also be used according to the above description.

  The sealing resin composition of the present invention includes a silsesquioxane (for example, a ladder structure) other than the silsesquioxane (A) and the silsesquioxane (B) as long as the object of the present invention is not impaired. It is not excluded to use (for example, about 0.1 to 5 mol%) in combination.

In the sealing resin composition of the present invention, other additives can be used as long as the object of the present invention is not impaired. Examples of such additives include silane coupling agents, hindered amine light stabilizers, hindered phenol antioxidants, and the like. Examples of the silane coupling include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4- (Epoxycyclohexyl) ethyltriethoxysilane, bilnitrimethoxysilane, bilnitriethoxysilane and the like. Examples of the hindered amine light stabilizer include TINUVIN (registered trademark) 770, TINUVIN (registered trademark) 622LD (both manufactured by Ciba Specialty Chemicals), and Adekastab (registered trademark) LA-57 (manufactured by Asahi Denka Kogyo Co., Ltd.). Etc. Examples of the hindered phenol antioxidant include IRGANOX (registered trademark) 1010 (manufactured by Ciba Special Te Chemicals), NOCRACK NS-30 (trade name) (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.), Tominox TT (commodity Name) (manufactured by Yoshitoyo Fine Chemical Co., Ltd.).
However, it is preferable not to use a solvent.

The amount of the silane coupling agent is preferably 0.1 to 5 phr, more preferably 0.5 to 2 phr in the composition.
The blending amount of the hindered amine light stabilizer is preferably 0.01 to 0.5 phr, more preferably 0.1 to 0.3 phr in the composition.
The blending amount of the hindered phenolic antioxidant is preferably 0.01 to 0.5 phr, more preferably 0.1 to 0.3 phr in the composition.

  The sealing resin composition of the present invention uses a curing accelerator that causes coloration because the silsesquioxane (A) and / or the silsesquioxane (B) can be cured by a hydrosilylation reaction. There is no need to do. For this reason, the cause of coloring due to heating can be effectively eliminated, and there is almost no thermal coloring due to heat exposure during the manufacturing process or use of the optical element, and it can be suitably used as a sealing resin. .

  Examples of the optical element to which the sealing resin composition of the present invention can be applied include a light emitting element, a light receiving element, a composite optical element, an optical integrated circuit, and the like, and specifically, for example, an LED, an LD, and the like. . A light emitting element such as an LED is generally composed of an LED chip, a lead frame, a gold wire, and a sealing resin. For example, in the structure of a near-ultraviolet LED, an electrode wiring submount is generally installed on a metal stem, and an LED chip is mounted thereon. A near-ultraviolet LED element is formed by sealing the chip on the submount with the sealing resin composition of the present invention. Moreover, in order to set it as white light emitting LED, the fluorescent substance layer may be arrange | positioned on the LED chip. This phosphor layer can be formed using the sealing resin composition of the present invention. In general, a sealing material is further applied thereon to form a white light emitting LED. Similarly, high-intensity blue light-emitting LEDs can be formed using the sealing resin composition of the present invention. The element of the present invention is an optical element in which the sealing resin composition of the present invention is used, as the above-described exemplary embodiment shows.

  Hereinafter, the present invention will be described more specifically with reference to synthesis examples and examples. However, the following description is exclusively for the purpose of explanation, and the present invention is not limited thereto.

Synthesis example 1
A 200 ml eggplant flask was charged with 10 ml of a 50% aqueous choline hydroxide solution and 10 ml of triethoxysilane and stirred at room temperature for 3 hours to obtain a choline silicate. The whole amount was dissolved in 10 ml of methanol, and slowly dropped into a mixture of 21.64 g of vinyldimethylchlorosilane and 19.5 ml of n-hexane while maintaining the internal temperature at 20 ° C. Thereafter, the mixture was transferred to a separatory funnel, the n-hexane phase was recovered, the solvent was distilled off, and the residue was washed with acetonitrile, so that a caged silsesquioxane T8 having one vinyldimethylsiloxy group per eight silicon atoms. Of 3.0 g was obtained (this is referred to as SQ-V). The assumed chemical structure of this product is shown below.

Synthesis example 2
A 200 ml eggplant flask was charged with 10 ml of a 50% aqueous choline hydroxide solution and 10 ml of triethoxysilane and stirred at room temperature for 3 hours to obtain a choline silicate. The whole amount was dissolved in 10 ml of methanol, and slowly dropped into a mixture of 16.92 g of dimethylchlorosilane and 19.5 ml of n-hexane while maintaining the internal temperature at 20 ° C. Thereafter, the mixture was transferred to a separatory funnel, and the n-hexane phase was recovered. After the solvent was distilled off, the residue was washed with acetonitrile, and the cage-like silsesquioxane T8 having one dimethylsiloxy group per eight silicon atoms was obtained. 4.5 g was obtained (this is referred to as SQ-H). The assumed chemical structure of this product is shown below.

Synthesis example 3
A 200 ml eggplant flask was charged with 6.13 g (5 mmol) of SQ-V and 76 ml of n-hexane and dissolved completely, and 3.34 g (15 mmol) of heptamethyltrisiloxane and 17.2 μl of platinum catalyst SIP6831.2 were added to room temperature. For 2 hours. Thereafter, 1 g of activated carbon was added and stirred for 1 hour, followed by filtration. The solvent of the filtrate was distilled off to obtain the desired liquid silsesquioxane derivative SQ-1 (vinyl equivalent 379 g / eq). An example of the assumed chemical structure of this is shown below.

Synthesis example 4
A 200 ml eggplant flask was charged with 5.09 g (5 mmol) of SQ-H and 76 ml of n-hexane and dissolved completely, and 2.10 g (25 mmol) of 1-hexene and 17.2 μl of platinum catalyst SIP6831.2 were added at room temperature. The reaction was performed for 2 hours. Thereafter, 1 g of activated carbon was added and stirred for 1 hour, followed by filtration. The solvent of the filtrate was distilled off to obtain a desired liquid silsesquioxane derivative SQ-2 (Si-H equivalent 480 g / eq). An example of the assumed chemical structure of this is shown below.

Synthesis example 5
A 200 ml eggplant flask was charged with 5.09 g (5 mmol) of SQ-H and 76 ml of n-hexane, dissolved completely, and 4.97 g (20 mmol) of vinylheptamethyltrisiloxane and 17.2 μl of platinum catalyst SIP6831.2 were added. The reaction was allowed to proceed for 2 hours at room temperature. Thereafter, 1 g of activated carbon was added and stirred for 1 hour, followed by filtration. The solvent of the filtrate was distilled off to obtain a desired liquid silsesquioxane derivative SQ-3 (Si-H equivalent 503 g / eq). An example of the assumed chemical structure of this is shown below.

Synthesis Example 6
A reaction vessel equipped with a stirrer and a thermometer was charged with 150 g of isopropanol, 5.4 g of a 10% aqueous solution of tetramethylammonium hydroxide (270 mmol of water, 5.93 mmol of tetramethylammonium hydroxide), and 12 g of water. 42.5 g (180 mmol) of glycidoxypropyltrimethoxysilane was gradually added, and the mixture was reacted at room temperature with stirring for 20 hours. Thereafter, 200 g of toluene was added, and the pressure was reduced to remove isopropanol. After washing with distilled water until the aqueous phase became neutral, toluene was distilled off under reduced pressure to obtain the desired epoxy group-containing silsesquioxane derivative SQ-4. (Epoxy equivalent 175 g / eq) was obtained. The assumed chemical structure of this product is shown below.

Examples 1-2, Comparative Example 1
A test piece was prepared using the resin composition of each example and the resin composition of the comparative example, and the performance was evaluated by the following method. The results are shown in Table 1. In Table 1, the meanings of the abbreviations are as follows.
MH-700G: methylhexahydrophthalic anhydride-hexahydrophthalic anhydride (70:30 mixture, acid anhydride equivalent: 168 g / eq) (manufactured by Shin Nippon Chemical Co., Ltd.)
TPP-PB: Tetramethylphosphonium bromide (Hokuko Chemical Co., Ltd.)
SIP6831.2: 2.3% xylene solution of divinyltetramethyldisiloxane / platinum complex (manufactured by Gelest)

Evaluation method Preparation of test piece:
The composition shown in Table 1 is poured into a 40 × 25 × 1 mm silicone mold, and the composition of Example 1 and Example 2 is heated at 120 ° C./2 hours, and the composition of the comparative example is heated at 120 ° C./10 hours. To obtain a test piece for measuring transmissivity.
Initial light transmittance (%):
The transmissivity at 350 nm was measured using an ultraviolet-visible spectrometer UV-2450 (manufactured by Shimadzu Corporation).
Transmittance after UV exposure (%):
The above-mentioned method after exposing the test piece for measuring transmissivity for 100 hours (83 ° C., relative humidity 20%, irradiance 1.24 kW / m 2) using a metering weather meter M6T (manufactured by Suga Test Instruments Co., Ltd.) The light transmittance was measured.
Permeability after heat exposure (%):
The test piece for light transmittance measurement was heated in an oven at 150 ° C. for 100 hours, and then the light transmittance was measured by the above method.

  From the results of Examples, Examples 1 and 2 in which the silsesquioxane derivative in the present invention was used as a resin component and the encapsulating resin composition was crosslinked by a hydrosilylation reaction had very high transmittance after heat exposure, The heat-resistant coloring property was greatly improved as compared with Comparative Example 1 in which a silsesquioxane resin having no configuration of the present invention was used as a resin component. On the other hand, Comparative Example 1 using an epoxy curing system caused thermal coloring due to heat exposure, and the transmittance was greatly reduced. Also, in UV exposure, Examples 1 and 2 have a slight decrease from the initial transmittance as compared with Comparative Example 1, and the initial transmittance itself is higher than that of Comparative Example 1 and is transparent. It was found to be excellent in UV resistance.

The encapsulating resin composition of the present invention is extremely excellent in heat resistance colorability, hardly causes thermal coloring due to heat exposure during the manufacturing process or use of the optical element, and is extremely suitable as an optical element sealing material. For example, it is useful as a sealing material for LEDs that are expected to further increase in brightness in the future.

Claims (7)

The following general formula (I):
_{(R1-SiO 3/2) a-} n (X1-SiO 3/2) n (I)
(In the formula, R1 is a hydrocarbon group having 2 to 12 carbon atoms (including carbon in the aliphatic carbon-carbon unsaturated bond) containing an aliphatic carbon-carbon unsaturated bond, or aliphatic. A silyloxy group containing a carbon-carbon unsaturated bond and no H-Si bond, and when there are a plurality of R 1 s, they may be the same or different, and X 1 is an H-Si bond and an aliphatic carbon- It is a monovalent organic group containing no carbon unsaturated bond, provided that X1 is not a hydrogen atom, and when there are a plurality of X1, they may be the same or different, and a is an even number of 6 to 14. N is a positive integer smaller than a.) Liquid silsesquioxane (A) having a cage structure containing an aliphatic carbon-carbon unsaturated bond and no H-Si bond And the following general formula (II):
(R2-SiO3 _{/ 2} ) _a-n (X2-SiO3 _{/ 2} ) _n (II)
(In the formula, R2 represents a hydrogen atom or a monovalent organic group containing an H-Si bond and no aliphatic carbon-carbon unsaturated bond. X2 is a monovalent organic group that does not contain an H-Si bond and an aliphatic carbon-carbon unsaturated bond, provided that X2 is not a hydrogen atom. A may be the same or different, a is an even number from 6 to 14. n is a positive integer smaller than a and contains an H—Si bond and is aliphatic carbon-carbon unsaturated. A resin composition for encapsulating an optical element, comprising at least one silsesquioxane selected from the group consisting of a liquid silsesquioxane (B) having a saddle type structure containing no bond as a resin component. The composition according to claim 1, wherein both the silsesquioxane (A) and the silsesquioxane (B) have a structural formula in which a is 8, 10 or 12. The composition according to claim 2, wherein both the silsesquioxane (A) and the silsesquioxane (B) have a hexahedral structural formula in which a is 8. 4. The composition according to claim 3, wherein n is 3 to 5 in both the silsesquioxane (A) and the silsesquioxane (B). Furthermore, the composition in any one of Claims 1-4 containing the crosslinking agent which can be bridge | crosslinked by hydrosilylation reaction. Furthermore, the composition of any one of Claims 1-5 containing the catalyst of hydrosilylation reaction. An optical element sealed with the composition according to claim 1.