JP2012219117A - White thermosetting resin composition, and reflector for white light emitting diode consisting of cured product of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white thermosetting resin composition forming a cured product that has high light reflective performance and heat resistance (thermal stability), especially high thermal discoloration resistance, and can provide a light reflectivity higher than that of the conventional art.SOLUTION: This white thermosetting resin composition includes (A) an addition reaction product of (a) a compound having two Si-H in one molecule and (b) polycyclic hydrocarbon having two addition reactive C=C in one molecule. The addition reaction product has at least two addition reactive C=C in one molecule. The white thermosetting resin composition also includes (B) an addition reaction product having two or more Si-H in one molecule, (C) hydrosilylation reaction catalyst, and (D) white inorganic oxide powder whose surface is modified beforehand. The white thermosetting resin composition contains at least 60 vol% of (D) white inorganic oxide powder whose surface is modified beforehand.

Description

  The present invention relates to a white thermosetting resin composition that gives a cured product useful as a light reflecting material, particularly as a reflector material for a white LED (light emitting diode), and a reflector material for a white LED (light emitting diode) comprising the cured product.

  In recent years, optical semiconductor elements such as LEDs have been widely used as indicators and light sources because they emit light with high efficiency and are excellent in driving characteristics and lighting repetition characteristics. In particular, white LEDs are widely applied as backlights for display devices and camera flashes, and are also expected as next-generation lighting devices. In such a light emitting device, a material that reflects emitted light (hereinafter referred to as a reflector material) is mounted in order to increase the light extraction efficiency in the irradiation direction.

  Currently, polyphthalamide resins are widely used as reflector materials. However, the polyphthalamide resin is liable to deteriorate due to long-term use, particularly discoloration, peeling, and mechanical strength reduction, and is difficult to apply to recent high-power light emitting devices.

  In order to solve these problems, Patent Documents 1 to 3 propose B-stage type reflector materials containing epoxy resin and metal oxide as constituent components, and Patent Document 4 proposes a ceramic reflector material. However, these solid materials have excellent heat resistance and mechanical properties, but have poor fluidity at room temperature, and thus have problems in handling and workability such as requiring high temperature for molding. In addition, since the solid material has poor fluidity even at high temperatures, there is a problem in the process such as difficulty in forming a fine structure or a large-area structure. Patent Document 5 proposes a cured silicone resin that is particularly useful as a reflector material for white LEDs (light-emitting diodes), but is not satisfactory in the initial light reflectance at wavelengths of 430 to 800 nm. On the other hand, Patent Document 6 proposes a curable composition containing a polycyclic hydrocarbon skeleton-containing component that gives a cured product having high transparency, but what is described about the problem of improving light reflectivity? Nor.

Japanese Patent No. 2656336 JP 2008-106226 A JP 2008-189833 A JP 2008-117932 A JP 2010-202831 A Japanese Patent No. 4520251

  The present invention has been made in view of the above circumstances, and provides a cured product that is excellent in light reflection performance, heat resistance (thermal stability), particularly heat-resistant discoloration, and can obtain a higher light reflectivity than before. A white thermosetting resin composition is provided. That is, the present invention relates to a white light-emitting material comprising a white thermosetting resin composition that gives a resin cured product (hereinafter also referred to as a cured product) useful as a light reflecting material, particularly a white LED reflector material, and a cured product of the composition. It aims at providing the reflector for diodes.

（式中、Ａは、下記一般式（２）：

で表される基から成る群から選ばれる２価の基であり、Ｒは、独立に非置換若しくは置換の炭素原子数１〜１２の１価炭化水素基、又は炭素原子数１〜６のアルコキシ基である。）で表されるケイ素原子に結合した水素原子を１分子中に２個有する化合物と、
（ｂ）付加反応性炭素−炭素二重結合を１分子中に２個有する多環式炭化水素と
の付加反応生成物であって、かつ、付加反応性炭素−炭素二重結合を１分子中に少なくとも２個有する付加反応生成物、
（Ｂ）ケイ素原子に結合した水素原子を１分子中に２個以上有するオルガノハイドロジェンポリシロキサン、
（Ｃ）ヒドロシリル化反応触媒、及び
（Ｄ）予め表面改質された白色無機酸化物粉体
を含有し、前記（Ｄ）予め表面改質された白色無機酸化物粉体を少なくとも６０体積％含有するものであることを特徴とする白色熱硬化性樹脂組成物を提供する。 In order to solve the above problems, according to the present invention,
(A) (a) The following general formula (1):

(In the formula, A represents the following general formula (2):

And R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, or alkoxy having 1 to 6 carbon atoms. It is a group. A compound having two hydrogen atoms bonded to a silicon atom represented by
(B) an addition reaction product with a polycyclic hydrocarbon having two addition-reactive carbon-carbon double bonds in one molecule, and the addition-reactive carbon-carbon double bond in one molecule An addition reaction product having at least two
(B) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule;
(C) a hydrosilylation reaction catalyst, and (D) a white inorganic oxide powder that has been surface-modified in advance, and (D) at least 60% by volume of the white inorganic oxide powder that has been surface-modified in advance. A white thermosetting resin composition is provided.

  A cured product obtained by thermosetting such a white thermosetting resin composition is excellent in light reflection performance, heat resistance (thermal stability), particularly heat discoloration, and has a higher reflectance than before. It will be a thing.

（式中、Ｒ’は非置換又は置換の炭素原子数２〜１２のアルケニル基である。） Examples of the component (b) include alkenyl norbornene compounds represented by the following general formula (3).

(In the formula, R ′ is an unsubstituted or substituted alkenyl group having 2 to 12 carbon atoms.)

  Thus, (b) the alkenyl norbornene compound represented by the above general formula (3) is exemplified as the polycyclic hydrocarbon having two addition-reactive carbon-carbon double bonds in one molecule. That is, the alkenyl norbornene compound has an addition-reactive carbon-carbon double bond formed between two adjacent carbon atoms among the carbon atoms forming the polycyclic skeleton of the polycyclic hydrocarbon. And a hydrogen atom bonded to a carbon atom forming a polycyclic skeleton of a polycyclic hydrocarbon is an addition-reactive carbon-carbon double bond-containing group (an unsubstituted or substituted alkenyl group having 2 to 12 carbon atoms) ).

  In this case, the component (b) is a combination of 5-vinylbicyclo [2.2.1] hept-2-ene, 6-vinylbicyclo [2.2.1] hept-2-ene, and combinations thereof. It is preferable that any one of them.

  Thus, examples of the component (b) include 5-vinylbicyclo [2.2.1] hept-2-ene and 6-vinylbicyclo [2.2.1] hept-2-ene. By using such a component (b), the cured product obtained from the white thermosetting resin composition is further excellent in light reflection performance, heat resistance (thermal stability), particularly heat discoloration, Compared to the above, it has a higher reflectance.

  In this case, the initial light reflectance at a wavelength of 430 to 800 nm of the cured product of the white thermosetting resin composition is 95% or more, and the light reflectance after being left at 150 ° C. for 2,000 hours is 90% or more. can do.

  In the case of a white thermosetting resin composition containing at least 60% by volume of the previously surface-modified white inorganic oxide powder of the component (D), the initial light reflectance at a wavelength of 430 to 800 nm is 95% or more. A cured product having a light reflectance of 90% or more after standing at 150 ° C. for 2,000 hours is obtained, that is, excellent in light reflection performance, heat resistance (thermal stability), particularly heat discoloration, It has been found that a cured product capable of achieving a higher light reflectivity can be obtained.

  In this case, the white thermosetting resin composition can be used for a light reflecting material.

  The cured product obtained from the white thermosetting resin composition of the present invention can obtain a sufficient reflectance as a light reflecting material.

  Moreover, this invention provides the reflector for white light emitting diodes which consists of hardened | cured material of the said white thermosetting resin composition.

  The white thermosetting resin composition of the present invention can be suitably used as a reflector material for light emitting devices such as LEDs, particularly for white light emitting diodes.

  Moreover, this invention provides the reflector for white light emitting diodes which shape | molded the said white thermosetting resin composition by the injection molding method. The present invention also provides a white light-emitting diode reflector, wherein the white thermosetting resin composition is formed by a transfer molding method.

  The white thermosetting resin composition of the present invention can be used as a reflector by applying to a conventionally used molding method such as an injection molding method or a transfer molding method.

  The cured product obtained by thermosetting the white thermosetting resin composition of the present invention is excellent in light reflection performance, heat resistance (thermal stability), particularly heat discoloration, and has a higher light reflectance than in the past. Can be obtained. Therefore, the cured product is useful as a light reflecting material, for example, a reflector material for a light emitting device, particularly for a white LED.

Hereinafter, the present invention will be described in more detail.
As described above, the composition for obtaining a conventional reflector material has a problem that a cured product satisfying the reflectance at a wavelength of 430 to 800 nm after initial and after heat resistance cannot be obtained. Therefore, a white thermosetting resin composition that is excellent in light reflection performance, heat resistance (thermal stability), particularly heat resistant discoloration, and can provide a resin cured product useful as a light reflecting material, and the white thermosetting resin There is a need for a cured product obtained from the composition and a light reflecting material comprising the cured product.

  As a result of intensive studies to achieve the above object, the present inventors have completed the present invention. That is, the present inventors include at least the following components (A) to (D), and at least 60% by volume of a previously surface-modified white inorganic oxide powder as the component (D). If it is a white thermosetting resin composition, the hardened | cured material whose initial light reflectivity in wavelength 430-800nm is 95% or more, and the light reflectivity after leaving at 150 degreeC and 2,000 hours is 90% or more is obtained. That is, it has been found that a cured product that is excellent in light reflection performance, heat resistance (thermal stability), particularly heat discoloration, and can achieve higher light reflectivity than before can be obtained. In the present specification, the reflectance of light means a value measured by a spectrophotometer device equipped with an integrating sphere.

（式中、Ａは、下記一般式（２）：

で表される基から成る群から選ばれる２価の基であり、Ｒは、独立に非置換若しくは置換の炭素原子数１〜１２の１価炭化水素基、又は炭素原子数１〜６のアルコキシ基である。）で表されるケイ素原子に結合した水素原子を１分子中に２個有する化合物と、
（ｂ）付加反応性炭素−炭素二重結合を１分子中に２個有する多環式炭化水素と
の付加反応生成物であって、かつ、付加反応性炭素−炭素二重結合を１分子中に少なくとも２個有する付加反応生成物
（Ｂ）ケイ素原子に結合した水素原子を１分子中に２個以上有するオルガノハイドロジェンポリシロキサン
（Ｃ）ヒドロシリル化反応触媒
（Ｄ）予め表面改質された白色無機酸化物粉体
を含有し、前記（Ｄ）予め表面改質された白色無機酸化物粉体を少なくとも６０体積％含有するものであることを特徴とする白色熱硬化性樹脂組成物である。 That is, the present invention
(A) (a) The following general formula (1):

(In the formula, A represents the following general formula (2):

And R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, or alkoxy having 1 to 6 carbon atoms. It is a group. A compound having two hydrogen atoms bonded to a silicon atom represented by
(B) an addition reaction product with a polycyclic hydrocarbon having two addition-reactive carbon-carbon double bonds in one molecule, and the addition-reactive carbon-carbon double bond in one molecule (B) organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule (C) hydrosilylation reaction catalyst (D) white surface-modified in advance A white thermosetting resin composition comprising inorganic oxide powder and containing (D) at least 60% by volume of a previously surface-modified white inorganic oxide powder.

  The present invention will be described in detail below. In this specification, Me and Ph represent a methyl group and a phenyl group, respectively, and the viscosity is a value measured by a rotational viscometer.

（式中、Ａは、下記一般式（２）：

で表される基から成る群から選ばれる２価の基であり、Ｒは、独立に非置換若しくは置換の炭素原子数１〜１２の１価炭化水素基、又は炭素原子数１〜６のアルコキシ基である。）で表されるケイ素原子に結合した水素原子を１分子中に２個有する化合物と、
（ｂ）付加反応性炭素−炭素二重結合を１分子中に２個有する多環式炭化水素と
の付加反応生成物であって、かつ、付加反応性炭素−炭素二重結合を１分子中に少なくとも２個有する付加反応生成物である。以下、これらの（ａ）成分および（ｂ）成分について説明する。 (A) component (A) component of the white thermosetting resin composition of this invention is
(A) The following general formula (1):

(In the formula, A represents the following general formula (2):

And R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, or alkoxy having 1 to 6 carbon atoms. It is a group. A compound having two hydrogen atoms bonded to a silicon atom represented by
(B) an addition reaction product with a polycyclic hydrocarbon having two addition-reactive carbon-carbon double bonds in one molecule, and the addition-reactive carbon-carbon double bond in one molecule Is an addition reaction product having at least two. Hereinafter, the component (a) and the component (b) will be described.

（Ｒは、独立に非置換もしくは置換の炭素原子数１〜１２の、好ましくは１〜６の、１価炭化水素基、又は炭素原子数１〜６の、好ましくは１〜４の、アルコキシ基である。）
で表される化合物が挙げられる。 <(A) component>
(A) Compound which is a reaction raw material of component (a) A compound having two hydrogen atoms bonded to the silicon atom represented by the above general formula (1) (hereinafter sometimes referred to as “SiH”) in one molecule In the general formula (1), A is a divalent group selected from the group consisting of the groups represented by the general formula (2), and the compound (a) includes the following general formula (a -1) to (a-3):

(R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. .)
The compound represented by these is mentioned.

  In the above formulas (a-1) to (a-3), when R is the monovalent hydrocarbon group, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group Alkyl groups such as pentyl group, isopentyl group, hexyl group and sec-hexyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; aryl groups such as phenyl group, o-, m- and p-tolyl; benzyl group, Aralkyl groups such as 2-phenylethyl group; alkenyl groups such as vinyl group, allyl group, 1-butenyl group, 1-hexenyl group; alkenyl aryl groups such as p-vinylphenyl group; and carbon atoms in these groups One or more bonded hydrogen atoms are substituted with a halogen atom, a cyano group, an epoxy ring-containing group, etc., for example, a chloromethyl group, a 3-chloropropyl group Halogenated alkyl groups such as 3,3,3-trifluoropropyl group; a 2-cyanoethyl group; 3-glycidoxypropyl group and the like.

Moreover, as a case where R is the said alkoxy group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, a tert-butoxy group etc. are mentioned, for example.
Among the above, as R, those other than alkenyl group and alkenylaryl group are preferable, and those in which all of them are methyl groups are preferable because they are easy to produce industrially and are easily available. .

Examples of the compounds represented by the general formulas (a-1) to (a-3) include, for example,
Structural _{formula: HMe 2 Si-p-C} 6 H 4 -SiMe 2 H
1,4-bis (dimethylsilyl) benzene represented by
Structural _{formula: HMe 2 Si-m-C} 6 H 4 -SiMe 2 H
1,3-bis (dimethylsilyl) benzene represented by
Structural formula: HMe ₂ Si—o—C ₆ H ₄ —SiMe ₂ H
And a silphenylene compound such as 1,2-bis (dimethylsilyl) benzene represented by the formula:
In addition, the said (a) component which is a reaction raw material of this (A) component can be used even if single 1 type also combines 2 or more types.

<(B) component>
(B) Polycyclic hydrocarbon having two addition-reactive carbon-carbon double bonds in one molecule, which is a reaction raw material of component (A), the “addition reactivity” is bonded to a silicon atom. It means the property of being able to undergo the addition of a hydrogen atom (known as a hydrosilylation reaction).

  In addition, as the form of the addition-reactive carbon-carbon double bond present in two molecules in the component (b), (i) the carbon atom forming the polycyclic skeleton of the polycyclic hydrocarbon Among them, those having two addition-reactive carbon-carbon double bonds formed between two adjacent carbon atoms, (ii) bonded to a carbon atom forming a polycyclic skeleton of a polycyclic hydrocarbon Those in which two hydrogen atoms are substituted by an addition-reactive carbon-carbon double bond-containing group, or (iii) carbon atoms forming a polycyclic skeleton of a polycyclic hydrocarbon, adjacent to each other An addition-reactive carbon-carbon double bond is formed between two carbon atoms, and the hydrogen atom bonded to the carbon atom forming the polycyclic skeleton of the polycyclic hydrocarbon is an addition-reactive carbon- Any one substituted by a carbon double bond-containing group is acceptable. No. Here, examples of the addition-reactive carbon-carbon double bond-containing group include alkenyl groups such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group, norbornyl group, particularly those having 2 to 12 carbon atoms. Etc.

（式中、Ｒ’は非置換又は置換の炭素原子数２〜１２のアルケニル基である。）
で表されるアルケニルノルボルネン化合物が挙げられる。さらに、該一般式（３）で表される化合物の具体例として、下記構造式（３−１）：

で表される５−ビニルビシクロ［２．２．１］ヘプト−２−エン、
下記構造式（３−２）：

で表される６−ビニルビシクロ［２．２．１］ヘプト−２−エン、およびこれら両者の組み合わせが挙げられる（以下、これら３者を区別する必要がない場合は、「ビニルノルボルネン」と総称することがある）。 Examples of the component (b) include the following general formula (3):

(In the formula, R ′ is an unsubstituted or substituted alkenyl group having 2 to 12 carbon atoms.)
The alkenyl norbornene compound represented by these is mentioned. Furthermore, as a specific example of the compound represented by the general formula (3), the following structural formula (3-1):

5-vinylbicyclo [2.2.1] hept-2-ene represented by:
The following structural formula (3-2):

6-vinylbicyclo [2.2.1] hept-2-ene, and a combination of the two (hereinafter, when there is no need to distinguish these three, it is generically called “vinyl norbornene”) Sometimes).

  The substitution position of the alkenyl group in the alkenyl norbornene compound (substitution position of the vinyl group of vinyl norbornene in the above structural formulas (3-1) and (3-2)) is a cis configuration (exo configuration) or a trans configuration ( Any of the above-mentioned isomers may be used, and there is no particular difference in the reactivity of the components due to the difference in the arrangement.

<Preparation of component (A)>
The component (A) of the white thermosetting resin composition of the present invention has one molecule of addition-reactive carbon-carbon double bond per mole of the component (a) having two SiHs in one molecule. 2 moles of the above component (b) in excess of 1 mole, for example, 10 moles or less (preferably more than 1 mole, for example, 5 moles or less) is added in the presence of a hydrosilylation reaction catalyst. That is, it can be obtained as an addition reaction product having no SiH and having at least two addition-reactive carbon-carbon double bonds in one molecule.

  The component (A) thus obtained uses an addition molar amount of the component (b) relative to the component (a) for the preparation, so that the addition-reactive carbon-carbon 2 derived from the structure of the component (b) is used. It has two heavy bonds in one molecule. Further, in addition to the addition-reactive carbon-carbon double bond derived from the component (b), an addition reaction derived from the component (a) (specifically, derived from R in the general formula (1)). The component (A) contains at least two addition-reactive carbon-carbon double bonds in one molecule since it may contain a reactive carbon-carbon double bond. This number is preferably 2 to 6, more preferably 2. If there are 2 to 6 addition-reactive carbon-carbon double bonds, the cured product obtained by curing the white thermosetting resin composition of the present invention is not likely to become brittle.

  Any conventionally known hydrosilylation reaction catalyst can be used. For example, carbon powder supporting platinum metal, platinum black, platinous chloride, chloroplatinic acid, reaction product of chloroplatinic acid and monohydric alcohol, complex of platinum and vinylsiloxane such as divinyltetramethyldisiloxane; Examples include complexes of chloroplatinic acid and olefins, platinum catalysts such as platinum bisacetoacetate; platinum group metal catalysts such as palladium catalysts and rhodium catalysts. Moreover, about addition reaction conditions, use of a solvent, etc., it will not be specifically limited, What is necessary is just to be normal.

  As described above, since the component (A) is prepared using an excess molar amount of the component (b) relative to the component (a), the component (A) has the structure of the component (b). It has two derived addition-reactive carbon-carbon double bonds in one molecule. Furthermore, the component (A) has a residue derived from the component (a), and the residue is derived from the structure of the component (b) but does not have an addition-reactive carbon-carbon double bond. It may contain a structure linked by a divalent residue of a polycyclic hydrocarbon.

That is, as the component (A), for example, the following general formula (A-1):
YX- (Y'-X) pY (A-1)
(In the formula, X is a divalent residue derived from the structure of the component (a), Y is a monovalent residue derived from the structure of the polycyclic hydrocarbon of the component (b), Y ′ is a divalent residue derived from the structure of component (b) above, and p is an integer of 0 to 10, preferably 0 to 5.
The compound represented by these is mentioned.

で表される一価の残基（以下、これら６者を区別する必要がない場合は、これらを「ＮＢ基」と総称し、また、前記６者の構造を区別せずに「ＮＢ」と略記することがある。）が挙げられる。 In addition, about the value of p which is the number of the repeating units represented by said (Y'-X), adjusting the excess molar amount of said (b) component made to react with respect to 1 mol of said (a) component. It is possible to set by.
Specific examples of the divalent residue derived from the structure of the component (a) of X in the general formula (A-1) include —SiR ₂ —A—SiR ₂ — (wherein R and A are the same as above).
As Y in the general formula (A-1), specifically, for example, the following structural formula:

(Hereinafter, when it is not necessary to distinguish these six members, they are collectively referred to as “NB group”, and “NB” without distinguishing the structure of the six members) May be abbreviated.).

で表される二価の残基が挙げられる。
但し、上記構造式で表される非対称な二価の残基は、その左右方向が上記記載のとおりに限定されるものではなく、上記構造式は、実質上、個々の上記構造を紙面上で１８０度回転させた構造（鏡面体）をも含めて示している。 As Y ′ in the general formula (A-1), specifically, for example, the following structural formula:

The bivalent residue represented by these is mentioned.
However, the asymmetrical divalent residue represented by the above structural formula is not limited in the left-right direction as described above. The structure (mirror surface) rotated 180 degrees is also shown.

（式中、ｐは０〜１０の整数である。）
更に、本発明に係る（Ａ）成分は、１種単独でも２種以上を組み合わせても使用することができる。 Although the preferable specific example of (A) component represented by the said general formula (A-1) is shown below, it is not limited to this. The meaning of “NB” is as described above.

(In the formula, p is an integer of 0 to 10.)
Furthermore, the component (A) according to the present invention can be used singly or in combination of two or more.

< (B) component >
The organohydrogenpolysiloxane of component (B) is a cross-linking agent for the white thermosetting resin composition of the present invention and contains hydrogen atoms (SiH groups) bonded to at least two silicon atoms in one molecule. To do. Examples of the bonding position of the silicon atom-bonded hydrogen atom of the component (B) include a molecular chain terminal and / or a molecular chain side chain.

The component (B) may contain an organic group bonded to a silicon atom. The organic group bonded to the silicon atom of the component (B) is an unsubstituted or substituted monovalent hydrocarbon group excluding an alkenyl group. Preferably, for example, alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, cyclohexyl, octyl, pentyl, hexyl, heptyl; phenyl, tolyl Aryl groups such as a group, xylyl group and naphthyl group; aralkyl groups such as benzyl group and phenethyl group; and halogenated alkyl groups such as chloromethyl group, 3-chloropropyl group and 3,3,3-trifluoropropyl group Of these, an alkyl group, an aryl group, particularly a methyl group and a phenyl group are preferred.
Examples of the molecular structure of the component (B) include linear, cyclic, branched, and three-dimensional network structures.

The organohydrogenpolysiloxane of component (B) is, for example, the following average composition formula (4)
R ¹ _e H _f SiO _{(4-ef) / 2} (4)
(In the formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms excluding the alkenyl group. E is 0.7 to 2.1, and f is 0.001 to 1. 0 and e + f is a positive number satisfying 0.8 to 3.0, preferably e is 0.9 to 2.0, f is 0.01 to 1.0, and e + f is 1.0. It is a positive number satisfying ~ 2.5.)
And those having at least 2 (usually about 2 to 200), more preferably 3 to 100 silicon-bonded hydrogen atoms (SiH groups) in one molecule.

Examples of the organohydrogenpolysiloxane include 1,3,5,7-tetramethylcyclotetrasiloxane, trimethylsiloxy group-blocked methylhydrogenpolysiloxane at both ends, trimethylsiloxy group-blocked dimethylsiloxane and methylhydrogensiloxane copolymer Combined, dimethylhydrogensiloxy-blocked dimethylpolysiloxane at both ends, dimethylhydrogensiloxy-blocked dimethylsiloxane / methylhydrogensiloxane copolymer at both ends, dimethylhydrogensiloxy-blocked dimethylsiloxane / methylhydrogensiloxane / diphenyl at both ends Siloxane copolymer, trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, trimethylsiloxy at both ends Blocked methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane _{copolymer, (CH} 3) 2 _HSiO consisting _1/2 units and _{SiO 4/2} units, and copolymers _thereof, and _(CH 3) 2 _{HSiO 1/2} units ( A copolymer comprising CH ₃ ) ₃ SiO _1/2 units and SiO _4/2 units, (CH ₃ ) ₂ HSiO _1/2 units, SiO _4/2 units, and (C ₆ H ₅ ) SiO _3/2 units. And the like.

  The molecular structure of the organohydrogenpolysiloxane may be any of linear, cyclic, branched, and three-dimensional network structures, but the number of silicon atoms (or the degree of polymerization) in one molecule is 2 to 1. It is preferable to use about 1,000, especially about 3 to 300. The (B) component organohydrogenpolysiloxane may be used alone or in combination of two or more.

  The viscosity of component (B) at 25 ° C. is within the range of 1 to 1,000 mPa · s because the physical properties of the resulting silicone rubber are good and the handling workability of the composition is good. It is preferable to be within a range of 5 to 500 mPa · s.

  The blending amount of the component (B) is preferably such that the amount of hydrogen atoms bonded to the silicon atom in the component (B) is 1 mol with respect to 1 mol of the addition-reactive carbon-carbon double bond in the component (A). The amount is 5 to 3.0 mol, more preferably 0.8 to 2.0 mol. When the blending amount of the component (B) is such an amount that satisfies such conditions, it has more excellent characteristics, and is particularly useful as a reflector material.

< (C) component >
The hydrosilylation reaction catalyst which is the component (C) contained in the white thermosetting resin composition of the present invention is the same as that described in the above “Preparation of the component (A)”.
The blending amount of the component (C) in the composition of the present invention is not particularly limited as long as it is an effective amount as a catalyst, but the platinum group with respect to the sum of the components (A) and (B). The amount of the metal atom is preferably 1 to 500 ppm, particularly preferably about 2 to 100 ppm by mass. By setting the blending amount within the above range, the time required for the curing reaction becomes appropriate, and it is possible to suppress problems such as coloring of the cured product. Component (C) can be used alone or in combination of two or more.

< (D) component >
The component (D) contained in the white thermosetting resin composition of the present invention is a white inorganic oxide powder that has been surface-modified in advance. The white inorganic oxide powder is not particularly limited, but silica, alumina, titania, or a composite oxide powder of two or more of these is preferable. Examples of the surface modifier include organochlorosilanes such as dimethyldichlorosilane and methyltrichlorosilane, organoalkoxysilanes such as methyltrimethoxysilane and methyltriethoxysilane, and alkylsilazanes such as hexamethyldisilazane, and alkylsilazanes are preferred. A method of treating the surface modifier with the white inorganic oxide powder is not limited, and a usual treatment method can be used. Specifically, for example, white inorganic oxide powder is placed in a container equipped with a stirring device typified by a hensil mixer, stirred in a nitrogen atmosphere, and a surface modifier is sprayed to form white inorganic oxide powder. It can be carried out by mixing with the body and reacting by heating. The white inorganic oxide powder is excellent in light reflectance at a wavelength of 430 nm by performing a surface modification treatment in advance as compared with the case where the surface modification treatment is not performed.

The particle size of the component (D) is not particularly defined, but as the component (D), many particles having an average particle size in the range of 0.1 to 200 μm are generally commercially available and easy to handle, and in the range of 0.5 to 100 μm. Those are more preferred. When the average particle size of the component (D) is in the range of 0.1 to 200 μm, the white thermosetting resin composition of the present invention is likely to have good fluidity, and the cured product of the composition has a surface having a surface. Light reflection performance is improved effectively. In the present specification, the average particle diameter means a volume-based average particle diameter corresponding to 50% of the cumulative distribution obtained by a particle size distribution measuring apparatus using a laser light diffraction method.
Component (D) can be used singly or in combination of two or more, and the amount of component (D) is at least 60% by volume or more of the white thermosetting resin composition of the present invention. Thus, the cured product of the composition has excellent light reflection performance. In particular, the initial light reflectivity at a wavelength of 430 to 800 nm is 95% or more, and after heat resistance, for example, the light reflectivity after standing at 150 ° C. for 2,000 hours is 90% or more, which is sufficient as a reflector material. A cured product can be obtained. (D) When the compounding quantity of a component is less than 60 volume% of the white thermosetting resin composition of this invention, the initial stage light reflectivity in wavelength 430-800nm is 95% or more, 150 degreeC, 2 A cured product having a reflectance sufficient as a reflector material having a light reflectance of 90% or more after standing for 1,000 hours cannot be obtained.
The upper limit of the blending amount is not particularly limited as long as it is an amount that can be blended, but considering workability, it is preferably 90% by volume, particularly preferably 85% by volume of the white thermosetting resin composition.

< (E) component >
Moreover, it is preferable to mix | blend an adhesive improvement agent (E) component as an arbitrary component with the white thermosetting resin composition of this invention. The adhesiveness improver is not particularly limited as long as it can improve the self-adhesiveness of the composition. For example, organosilicon compound-based adhesion imparting agents and non-silicon based organic compound-based adhesion imparting agents can be mentioned. Specifically, examples of the organosilicon compound-based adhesion imparting agent include adhesion imparting agents composed of organosilicon compounds such as organosilanes and organopolysiloxanes other than the components (A) and (B). Examples of the non-silicon compound-based adhesion imparting agent include an adhesion imparting agent composed of an organic acid allyl ester, an epoxy ring-opening catalyst, or an organic titanium compound. These may be used alone or in combination of two or more.

（式中、ｎは１以上の整数である。） Examples of the organosilicon compound include an alkylene group directly bonded to a silicon atom, such as an alkenyl group such as a vinyl group or an allyl group; a γ-glycidoxypropyl group, or a β- (3,4-epoxycyclohexyl) ethyl group. An epoxy group bonded to a silicon atom through a carbon atom such as γ-acryloxypropyl group, γ-methacryloxypropyl group, an acryloxy group bonded to a silicon atom through a carbon atom such as an alkylene group, and a methacryloxy group An alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, or a butoxy group; trimethoxysilyl bonded to a silicon atom via an alkylene group, which may contain one or two ester structures, urethane structures, or ether structures; Group, alkoxysilyl group such as triethoxysilyl group, methyldimethoxysilyl group; isocyanate (A) the organosilane having at least one, preferably two or more functional groups selected from the group consisting of groups, 3 to 100 silicon atoms, preferably 3 to 50, more preferably 5 to 20; Other than the component (B), linear or cyclic siloxane oligomers, (allyl) silyl modified products of triallyl isocyanurate, siloxane derivatives thereof, etc., having two or more of these functional groups in one molecule Is preferred.
Specific examples of such an organosilicon compound include the following compounds.

(In the formula, n is an integer of 1 or more.)

The organic acid allyl ester has no silicon atom in the molecule, and examples thereof include an organic acid allyl ester having one alkenyl group and at least one ester group in one molecule.
Examples of organic acids include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and vinyl acetate; aromatic carboxylic acids such as benzoic acid, phthalic acid, and pyromellitic acid; saturated fatty acids such as acetic acid, propionic acid, butyric acid, and lauric acid Etc. Examples of organic acid allyl esters containing these organic acids include, for example, allyl esters such as unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and vinyl acetic acid; benzoic acid allyl ester, phthalic acid diallyl ester, pyromellitic acid tetraallyl ester, and the like. Aromatic carboxylic acid allyl esters of the following: saturated fatty acid allyl esters such as acetic acid allyl ester, propionic acid allyl ester, butyric acid allyl ester, valeric acid allyl ester, lauric acid allyl ester, and the like.

  The epoxy ring-opening catalyst has no silicon atom in the molecule, and examples thereof include epoxy ring-opening catalysts such as organometallic chelates, amines, amides, imidazoles, and acid anhydrides.

  The organic titanium compound has no silicon atom in the molecule, and specific examples thereof include tetrabutoxy titanium, tetrakis (2-ethylhexyloxy) titanium, tetrastearyloxy titanium, titanium stearate, tetraoctyloxy. Examples thereof include titanium, titanium isopropoxyoctylene glycolate, triethanolamine titanate, titanium acetylacetonate, titanium ethylacetonate, titanium lactonate, and oligomers and polymers that are the condensation reaction products thereof.

  (E) The compounding quantity of a component becomes like this. Preferably it is 0.5-30 mass parts with respect to a total of 100 mass parts of the said (A) component and (B), More preferably, it is 1-20 mass parts. When the blending amount is 0.5 to 30 parts by mass, the white thermosetting resin composition of the present invention and the cured product thereof are effectively improved in adhesion to the substrate and are hardly colored.

で表される２−（ビシクロ［２．２．１］ヘプト−２−エン−５−イル）エチル基および
下記構造式：

で表される２−（ビシクロ［２．２．１］ヘプト−２−エン−６−イル）エチル基のいずれか一方または両方の中に存在する炭素−炭素二重結合が含まれている場合がある。そして、前記炭素−炭素二重結合が含まれていると、大気中の酸素により酸化され前記硬化物が着色する原因となる。そこで、本発明の白色熱硬化性樹脂組成物に、必要に応じ、酸化防止剤を配合することにより前記着色を未然に防止することができる。 Other blending components In addition to the above components, it is optional to blend other components with the white thermosetting resin composition of the present invention within a range that does not impair the objects and effects of the present invention. Examples of other components include those described below.
<Antioxidant>
In the cured product of the white thermosetting resin composition of the present invention, the addition reactive carbon-carbon double bond in the component (A) may remain unreacted, and the following structural formula:

2- (bicyclo [2.2.1] hept-2-en-5-yl) ethyl group represented by the following structural formula:

A carbon-carbon double bond present in one or both of 2- (bicyclo [2.2.1] hept-2-en-6-yl) ethyl group represented by There is. And when the said carbon-carbon double bond is contained, it will be oxidized by oxygen in air | atmosphere and will cause the said hardened | cured material to color. Then, the said coloring can be prevented beforehand by mix | blending antioxidant with the white thermosetting resin composition of this invention as needed.

  As the antioxidant, all conventionally known antioxidants can be used. For example, 2,6-di-t-butyl-4-methylphenol, 2,5-di-t-amylhydroquinone, 2, 5-di-t-butylhydroquinone, 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′- And methylene bis (4-ethyl-6-t-butylphenol). These can be used singly or in combination of two or more.

  In addition, when using this antioxidant, the compounding quantity should just be an effective amount as an antioxidant, and although it does not restrict | limit in particular, With respect to the sum total of the said (A) component and (B) component, Preferably, about 10 to 10,000 ppm, particularly preferably about 100 to 1,000 ppm is added on a mass basis. By setting the blending amount within the above range, it is possible to obtain a cured product that exhibits sufficient antioxidant ability, does not cause coloring, oxidative deterioration, and the like, and has more excellent light reflection performance.

<Others>
Moreover, in order to ensure pot life, addition reaction control agents, such as 1-ethynyl cyclohexanol and 3, 5- dimethyl- 1-hexyn-3-ol, can be mix | blended.
Furthermore, it is also possible to use a light stabilizer in order to impart resistance to light degradation caused by light energy such as light from the light emitting element and sunlight. As the light stabilizer, a hindered amine stabilizer that captures radicals generated by photooxidation degradation is suitable, and the antioxidant effect is further improved by using it together with the antioxidant. Specific examples of the light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 4-benzoyl-2,2,6,6-tetramethylpiperidine and the like.

Cured product A cured product can be obtained by molding and curing the white thermosetting resin composition of the present invention. The white thermosetting resin composition of the present invention can be applied to conventionally used molding methods such as an injection molding method and a transfer molding method. In addition, the curing conditions of the white thermosetting resin composition of the present invention vary depending on the amount and are not particularly limited. However, it is usually preferable to set the conditions at 100 to 180 ° C. for 10 to 300 minutes.

  In general, in order to function as a reflector material, the initial reflectance of visible light (wavelength: 430 to 800 nm) is preferably 95% or more (that is, 95 to 100%), more preferably 97% or more (that is, 97). ~ 100%). When the reflectance is 95% or more, when the cured product is used as a reflector material for a light-emitting device such as a lighting fixture, the light extraction efficiency becomes higher, and sufficient brightness can be easily secured. The reflectance is preferably 90% or more not only in the initial stage of production of the cured product but also after a heat resistance test (performed by leaving the cured product to stand at 150 ° C. for 2,000 hours). . The cured product obtained from the white thermosetting resin composition of the present invention has a reflectance of visible light (wavelength: 430 to 800 nm) of 95% or more, and a light reflectance after being left at 150 ° C. for 2,000 hours. It is 90% or more, and a sufficient reflectivity as a reflector material can be obtained. In the present specification, the reflectance of light means a value measured by a spectrophotometer device equipped with an integrating sphere.

Light reflecting material (reflector for white light emitting diode)
Moreover, in this invention, the light reflection material which consists of hardened | cured material of the said white thermosetting resin composition is provided. Although the use of this light reflection material is not specifically limited, For example, it can use suitably as reflector materials for light-emitting devices, such as LED, especially for white LED. A light emitting device such as a white LED using this reflector material can maintain high light extraction efficiency over a long period of time. Moreover, since the white thermosetting resin composition of this invention is easy to shape | mold, it is easy to make a reflector material into a desired shape in these light-emitting devices containing white LED.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.
(Synthesis Example) Preparation of Component (A) Into a 500 mL four-necked flask equipped with a stirrer, a condenser, a dropping funnel and a thermometer, vinyl norbornene (trade name: V0062, manufactured by Tokyo Chemical Industry Co., Ltd .; 5-vinylbicyclo [ 2.2.1] Heter-2-ene and 6-vinylbicyclo [2.2.1] hept-2-ene in an approximately equimolar amount of isomer mixture) 60 g (0.5 mol) was added to the oil. Heated to 85 ° C. using a bath. To this, 0.02 g of carbon powder supporting 5% by mass of platinum metal was added, and 38.8 g (0.2 mol) of 1,4-bis (dimethylsilyl) benzene was added dropwise over 25 minutes while stirring. After completion of dropping, the mixture was further stirred at 90 ° C. for 24 hours, and then cooled to room temperature. Thereafter, platinum metal-supported carbon was removed by filtration, and excess vinylnorbornene was distilled off under reduced pressure to obtain 79 g of a colorless and transparent oily reaction product (kinematic viscosity at 25 ° C .: 1220 mm ² / s).

および、
（３）ｐ−フェニレン基を３個有する化合物：約４モル％（下記に代表的な構造式の一例を示す）

の混合物であることが判明した。また、前記混合物全体（１００ｇ中）としての付加反応性炭素−炭素二重結合（ＮＢ基）の含有割合は、０．４０モル／１００ｇであった。
（表面処理１） （Ｄ−１）成分の調製
平均粒径１６．７μｍ、比表面積４．６ｍ^２／ｇの球状溶融石英粉（Ｄ−１未処理品）３００ｇを流動層処理装置に導入し、５０℃、窒素気流下、ヘキサメチルジシラザンを５質量％含有するヘキサン溶液３０ｇを３０分かけて噴霧処理し表面処理した。
（表面処理２） （Ｄ−２）成分の調製
平均粒径０．２μｍの酸化チタン粉（Ｄ−２未処理品）３００ｇを流動層処理装置に導入し、５０℃、窒素気流下、ヘキサメチルジシラザンを５質量％含有するヘキサン溶液３０ｇを３０分かけて噴霧処理し表面処理した。 As a result of analyzing the reaction product by FT-IR, NMR, GPC and the like,
(1) p-phenylene group one compound _{having: NBMe 2 Si-p-C} 6 H 4 -SiMe 2 NB about 72 mole%,
(2) Compound having two p-phenylene groups: about 24 mol% (an example of a typical structural formula is shown below),

and,
(3) Compound having three p-phenylene groups: about 4 mol% (an example of a typical structural formula is shown below)

It was found to be a mixture of Moreover, the content rate of the addition reactive carbon-carbon double bond (NB group) as the whole mixture (in 100 g) was 0.40 mol / 100 g.
(Surface Treatment 1) Preparation of Component (D-1) 300 g of spherical fused quartz powder (D-1 untreated product) having an average particle size of 16.7 μm and a specific surface area of 4.6 m ² / g was introduced into a fluidized bed treatment apparatus. A surface treatment was performed by spraying 30 g of a hexane solution containing 5% by mass of hexamethyldisilazane over 30 minutes under a nitrogen stream at 50 ° C.
(Surface Treatment 2) Preparation of Component (D-2) 300 g of titanium oxide powder (D-2 untreated product) having an average particle size of 0.2 μm was introduced into a fluidized bed treatment apparatus, and hexamethylated at 50 ° C. under a nitrogen stream. A surface treatment was performed by spraying 30 g of a hexane solution containing 5% by mass of disilazane over 30 minutes.

で表される化合物、
（Ｃ）白金−ジビニルテトラメチルジシロキサン錯体トルエン溶液（白金原子を１質量％含有）、
（Ｄ−１）表面処理１で得られた表面処理球状溶融石英粉末、
（Ｄ−２）表面処理２で得られた表面処理酸化チタン粉末、
（Ｅ−１）下記式：

で表される化合物、および
（Ｆ）１−エチニル−１−シクロヘキサノール（付加反応制御剤）
（Ｇ−１）ＣＨＩＭＡＳＳＯＢ １１９ＦＬ（光安定剤）
（Ｇ−２）ＩＲＧＡＮＯＸ３１１４（酸化防止剤）
を表１に示す配合量（単位：質量部）で配合し、実施例１、２、比較例１、２、おのおのの組成物を得た。即ち、まず、５リットルゲートーミキサー（井上製作所（株）製、商品名：５リットルプラネタリミキサー）に（Ａ）成分、（Ｄ）成分および（Ｇ）成分を表１に示す配合量で仕込み、室温にて１時間混合し、次に（Ｂ）成分、（Ｅ）成分および（Ｆ）成分を表１に示す配合量で加えて均一になるように室温にて３０分混合し、最後に（Ｃ）成分を表１に示す配合量で加えて均一になるように室温にて減圧下３０分混合して白色熱硬化性樹脂組成物を得た。尚、表１最下段には、各白色熱硬化性樹脂組成物中の（Ｄ）成分の容量組成（体積％）を示す。 (Examples 1 and 2, Comparative Examples 1 and 2)
(A) the reaction product obtained in Synthesis Example 1,
(B-1) HMe ₂ SiO (HMeSiO) ₂ (Ph ₂ SiO) ₂ SiMe ₂ H,
(B-2) The following formula:

A compound represented by
(C) Platinum-divinyltetramethyldisiloxane complex toluene solution (containing 1% by mass of platinum atoms),
(D-1) surface-treated spherical fused silica powder obtained by surface treatment 1,
(D-2) surface-treated titanium oxide powder obtained by surface treatment 2,
(E-1) The following formula:

And (F) 1-ethynyl-1-cyclohexanol (addition reaction control agent)
(G-1) CHIMASSOB 119FL (light stabilizer)
(G-2) IRGANOX 3114 (antioxidant)
Were blended in the blending amounts (unit: parts by mass) shown in Table 1, and Examples 1 and 2, Comparative Examples 1 and 2, and respective compositions were obtained. That is, first, the (A) component, the (D) component, and the (G) component were charged in a blending amount shown in Table 1 into a 5 liter gate mixer (product name: 5 liter planetary mixer manufactured by Inoue Seisakusho Co., Ltd.) Mix at room temperature for 1 hour, then add the components (B), (E) and (F) at the blending amounts shown in Table 1 and mix at room temperature for 30 minutes to be uniform. Component C) was added at the blending amount shown in Table 1 and mixed at room temperature under reduced pressure for 30 minutes to obtain a uniform white thermosetting resin composition. In addition, the capacity | capacitance composition (volume%) of (D) component in each white thermosetting resin composition is shown in the lowest stage of Table 1.

(Comparative Example 3)
It mix | blended with the compounding quantity (unit: mass part) shown in Table 1, and the composition of the comparative example 3 was obtained. That is, first, the (A) component and the (D) component (D-1 untreated product, D-2 untreated product) were added to a 5 liter gate mixer (Inoue Seisakusho Co., Ltd., trade name: 5 liter planetary mixer). And (G) component was prepared with the compounding quantity shown in Table 1, and 6 parts by mass of hexamethyldisilazane was further mixed at room temperature for 1 hour. Thereafter, the temperature was raised to 150 ° C., followed by mixing for 2 hours to remove excess hexamethyldisilazane and its decomposition products. Next, after the temperature is lowered to 30 ° C., the components (B), (E) and (F) are added at the blending amounts shown in Table 1 and mixed at room temperature for 30 minutes so as to be uniform. Component (C) was added in the amount shown in Table 1 and mixed at room temperature for 30 minutes under reduced pressure to obtain a white thermosetting resin composition. In addition, the capacity | capacitance composition (volume%) of (D) component in each white thermosetting resin composition is shown in the lowest stage of Table 1.

Next, the compositions of Examples 1, 2 and Comparative Examples 1, 2, and 3 were poured into molds and cured by pressure at 150 ° C. and 100 MPa for 10 minutes, and then in an oven at 150 ° C. and atmospheric pressure for 3 hours. Curing was performed to obtain a cured product having a thickness of 2 mm. The light reflectance characteristics of the obtained cured product are shown in Table 2 below.
The light reflectance was measured at 25 ° C. in the wavelength region of 430 to 800 nm using a spectrophotometer device U-3310 manufactured by Hitachi, Ltd. equipped with an integrating sphere. The initial (before test) light reflectance and the light reflectance after leaving for 2,000 hours at 150 ° C. were measured to evaluate the heat resistance.

  The cured product obtained from the white thermosetting resin composition (Examples 1 and 2) containing at least 60% by volume of the previously surface-modified white inorganic oxide powder according to the present invention has a wavelength of 430. The initial light reflectance at ˜800 nm is 95% or more, and the light reflectance after being left at 150 ° C. for 2,000 hours is 90% or more, resulting in a cured product having sufficient reflectance as a reflector material. . On the other hand, in the cured products obtained from the compositions of Comparative Examples 1, 2, and 3, the light reflectivity after heat resistance was not a sufficient value as a reflector material compared to Examples 1 and 2.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. It is contained in the technical range.

Claims (8)

(A) (a) The following general formula (1):

(In the formula, A represents the following general formula (2):

And R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, or alkoxy having 1 to 6 carbon atoms. It is a group. A compound having two hydrogen atoms bonded to a silicon atom represented by
(B) an addition reaction product with a polycyclic hydrocarbon having two addition-reactive carbon-carbon double bonds in one molecule, and the addition-reactive carbon-carbon double bond in one molecule An addition reaction product having at least two
(B) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule;
(C) a hydrosilylation reaction catalyst, and (D) a white inorganic oxide powder that has been surface-modified in advance, and (D) at least 60% by volume of the white inorganic oxide powder that has been surface-modified in advance. A white thermosetting resin composition characterized by comprising: The white thermosetting resin composition according to claim 1, wherein the component (b) is an alkenyl norbornene compound represented by the following general formula (3).

(In the formula, R ′ is an unsubstituted or substituted alkenyl group having 2 to 12 carbon atoms.)   The component (b) is any one of 5-vinylbicyclo [2.2.1] hept-2-ene, 6-vinylbicyclo [2.2.1] hept-2-ene, and combinations thereof. The white thermosetting resin composition according to claim 1 or 2, wherein the composition is a white thermosetting resin composition.   The initial light reflectance at a wavelength of 430 to 800 nm of the cured product of the white thermosetting resin composition is 95% or more, and the light reflectance after being left at 150 ° C. for 2,000 hours is 90% or more. The white thermosetting resin composition according to any one of claims 1 to 3.   The white thermosetting resin composition according to claim 1, wherein the white thermosetting resin composition is used for a light reflecting material.   The reflector for white light emitting diodes which consists of hardened | cured material of the white thermosetting resin composition of any one of Claims 1 thru | or 5.   A white light-emitting diode reflector, wherein the white thermosetting resin composition according to any one of claims 1 to 5 is molded by an injection molding method. A white light-emitting diode reflector, wherein the white thermosetting resin composition according to any one of claims 1 to 5 is formed by a transfer molding method.