JP5293525B2 - Composition for sealing an optical semiconductor element - Google Patents

Description

The present invention relates to a composition for sealing an optical semiconductor element such as an LED, and more specifically, includes a branched silicone resin in which an epoxy group is introduced into a silicone chain by an addition reaction, has a long pot life, and has a thermal shock resistance. It is related with the composition which gives the hardened | cured material excellent in these.

  Conventionally, epoxy resin compositions have been widely used to seal optical semiconductor elements. The epoxy resin composition usually contains an alicyclic epoxy resin, a curing agent and a curing catalyst. The composition is poured and cured by a molding method such as casting or transfer molding into a mold in which the optical semiconductor element is disposed, thereby sealing the optical semiconductor element. However, with the brightness and power of the LED, the color change deterioration of the epoxy resin has become a problem. In particular, the alicyclic epoxy resin has a problem of shortening the life of the LED element because it is yellowed by blue light or ultraviolet light.

  Therefore, a composition containing an epoxy-modified silicone obtained by modifying a silicone excellent in heat and light resistance with an epoxy compound has been proposed. Examples of the epoxy-modified silicone include a resin synthesized by condensing a silane having an epoxy group and silanol (Patent Document 1), a silsesquioxane having at least two epoxy rings (Patent Document 2), one Known is an organopolysiloxane composed of a functional siloxane unit (M unit) and a tetrafunctional siloxane unit (Q unit) in which an epoxy group is introduced (Patent Document 3).

  However, the composition containing these silicone resins has a low elastic modulus and is brittle. Therefore, the LED encapsulated with the composition has a problem that the resin easily cracks in the temperature cycle test.

Japanese Patent Laid-Open No. 7-97433 JP 2005-263869 A JP-A-7-18078

  In order to solve the above problems, the present inventors have invented a composition containing an epoxy-modified silicone resin having a predetermined linear polysiloxane structure (Japanese Patent Application No. 2008-195122). The present invention aims to further improve the composition in terms of thermal shock resistance and pot life.

As a result of various studies, the present inventors have found that the above object can be achieved by introducing an epoxy group into a silicone chain by an addition reaction, and have completed the present invention. That is, this invention is a composition for optical semiconductor element sealing containing the following (A), (B), (C) and (D).
(A) A branched silicone resin prepared by an addition reaction between an unsaturated group-containing epoxy compound and an organopolysiloxane having a SiH group, wherein 3 or more epoxy groups and 1 or more (R ¹ SiO _3/2 ) units, 3 or more (R ² R ³ R ⁴ SiO _1/2 ) units, and 3 or more (R ² R ³ SiO) _n (n is an integer of 1 to 20) structure, branched 100 parts by mass of silicone resin [R ¹ is a C _1-20 monovalent organic group, R ² and R ³ are independently of each other a C _1-20 monovalent organic group, and R ⁴ is a C _1-20 Monovalent organic group, provided that 3 or more of R ^{4 in} one molecule is an epoxy group-containing group]
(B) Non-aromatic epoxy resin having two or more epoxy groups per molecule (A) component and (B) 50 parts by mass or less with respect to 100 parts by mass in total (C) curing agent (A) component (D) Curing catalyst (A) component, (B) component, and (B) amount which becomes 0.4-1.5 mol of this epoxy group and a reactive group with respect to 1 mol in total of the epoxy group of (B) component C) 0.01 to 3 parts by mass with respect to 100 parts by mass in total of the components

  The composition for sealing an optical semiconductor element of the present invention has a long pot life and does not increase in viscosity during storage. Further, the cured product of the composition is excellent in thermal shock resistance while being high in hardness, and forms a good optical semiconductor package.

In the composition of the present invention, the branched silicone resin (A) is prepared by an addition reaction between an unsaturated group-containing epoxy compound and an organopolysiloxane having a SiH group. Thereby, a long pot life can be achieved as compared with the case where a silicone resin into which an epoxy group is introduced by a condensation reaction is included. The addition reaction is performed in the presence of a platinum catalyst according to a conventional method.

(A) The branched silicone resin has 3 or more epoxy groups per molecule. The epoxy group is contained in R ⁴ described later, and is saturated by the above addition reaction, for example, an ethylene group derived from a vinyl group, a propylene group derived from an allyl group, and further connects the saturated bond and the epoxy group. It is bonded to the silicon atom via a group. (A) The epoxy equivalent of the branched silicone resin is 200 to 1500 g / eq, preferably 200 to 1200 g / eq.

(A) The branched silicone resin has one or more (R ¹ SiO _3/2 ) units, three or more (R ² R ³ R ⁴ SiO _1/2 ) units, and three or more (R ² ) units per molecule. R ³ SiO) _n (n is an integer of 1 to 20) structure. Since it has a branch, the hardness of the cured product is high.

R ¹ , R ² , R ³ and R ⁴ are C _1-20 monovalent organic groups, provided that three or more of R ^{4 in} one molecule are epoxy group-containing groups. The monovalent organic group of C _1-20 includes an alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group, an alicyclic group such as a cyclopentyl group, a cyclohexyl group, and a norbornyl group, and an aryl group such as a phenyl group. Etc. Preferably, R ¹ is a phenyl group, and R ² and R ³ are methyl groups.

Examples of the epoxy group-containing group of R ⁴ include a γ-glycidoxyethyl group, a β- (3,4-epoxycyclohexyl) ethyl group, and combinations thereof. A β- (3,4-epoxycyclohexyl) ethyl group is preferred.

Preferably, (A) branched silicone resin is represented by following formula (2).

式（２）において、Ｒ^１〜Ｒ^４は上述のとおりであり、ｐ、ｑ、及びｒは１〜２０、好ましくは１〜１０、の整数であり、ｓは１〜５、好ましくは１〜２、の整数である。

In the formula (2), R ^{1 to} R ⁴ are as described above, p, q, and r are integers of 1 to 20, preferably 1 to 10, and s is 1 to 5, preferably 1 to 1. An integer of 2.

(A) As described above, the branched silicone resin is prepared by adding an epoxy compound having an unsaturated group such as a vinyl group to an organopolysiloxane having a SiH group in the presence of a metal catalyst such as platinum. . For example, those above formula (2) may be to turn organopolysiloxane having SiH groups at the ends represented by the following formula (3), obtained by addition reaction of an epoxy compound having an unsaturated group.

（式（３）において、Ｒ^１〜Ｒ^４、ｐ、ｑ、ｒ及びｓは上記のとおりである。）
該不飽和基を有するエポキシ化合物としては、ビニルシクロヘキセンモノオキサイド（セロキサイド２０００Ｚ、ダイセル化学工業社製）が例示される。

(In Formula (3), R ^{1 to} R ⁴ , p, q, r, and s are as described above.)
Examples of the epoxy compound having an unsaturated group include vinylcyclohexene monooxide (Celoxide 2000Z, manufactured by Daicel Chemical Industries).

The organopolysiloxane of the above formula (3) is, for example, an organosilicon compound represented by R ¹ SiX ₃ or HR ² R ³ SiX (X is a hydrolyzable group such as an alkoxy group) and (R ² R ³ SiO ) It can be synthesized by subjecting an organopolysiloxane having an n (n = 1 to 20) structure and having a hydrolyzable group at the terminal to hydrolysis and condensation reactions.

(B) Examples of non-aromatic epoxy resins having two or more epoxy groups per molecule include alicyclic epoxy resins such as (3,4-epoxycyclohexane) methyl 3 ′, 4′-epoxycyclohexyl carboxylate; Hydrogen aromatic rings such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, aralkyl type epoxy resin and biphenyl aralkyl type epoxy resin Examples include a hydrogenated epoxy resin added; a dicyclopentadiene epoxy resin. Of these, alicyclic epoxy resins are preferred in terms of light resistance.

(B) The compounding quantity of an epoxy resin is 50 mass parts with respect to a total of 100 mass parts of (A) component and (B) component, Preferably it is 40 mass parts or less. If it exceeds 50 parts by mass, the light resistance tends to be low.

(C) As a hardening | curing agent, the hardening | curing agent of arbitrary epoxy resins can be used, An amine type hardening | curing agent, a phenol type hardening | curing agent, and an acid anhydride type hardening | curing agent are mentioned. Preferably, an acid anhydride curing agent is used. Examples of the acid anhydride curing agent include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, 3-methyl-hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride, Or a mixture of 3-methyl-hexahydrophthalic anhydride and 4-methyl-hexahydrophthalic anhydride, tetrahydrophthalic anhydride, nadic anhydride, methyl nadic anhydride, norbornane-2,3-dicarboxylic anhydride, methyl norbornane- 2,3-dicarboxylic anhydride and the like can be mentioned.

(C) The compounding quantity of a hardening | curing agent is 0.4-1.5 mol with respect to the total of 1 mol of the epoxy group of (A) component in a composition, and (B) component, ie, 1 epoxy of all the epoxy resins. The curing agent is 0.4 to 1.5 equivalents, preferably 0.5 to 1.0 equivalents.

(D) Examples of curing catalysts include quaternary phosphonium salts such as tetrabutylphosphonium O, O-diethyl phosphorodithioate and tetraphenylphosphonium tetraphenylborate, and organic phosphine-based curing catalysts such as triphenylphosphine and diphenylphosphine. , 1,8-diazabicyclo (5,4,0) undecene-7, tertiary amine curing catalysts such as triethanolamine and benzyldimethylamine, imidazoles such as 2-methylimidazole and 2-phenyl-4-methylimidazole Among them, a quaternary phosphonium salt is preferable.

(D) The compounding amount of the curing catalyst is 100 parts by mass in total of the components (A), (B) and (C).
It is 0.01-3 mass parts. If the amount of the curing catalyst is less than the lower limit, the effect of promoting the reaction between the epoxy resin and the curing agent may not be sufficiently obtained. On the other hand, if the blending amount of the curing catalyst is larger than the upper limit value, it may cause discoloration during curing or a reflow test.

  In addition to the above components, conventional additives such as antioxidants, anti-discoloring agents, anti-degradation agents, inorganic fillers such as silica, silane coupling agents, and modifiers may be used without departing from the object of the present invention. Plasticizers, diluents and the like may be blended. Moreover, a phosphor for changing the wavelength, a titanium oxide fine powder, a light scattering agent such as silica, and the like can be added.

  The composition of the present invention is prepared by blending (A) a silicone resin, (B) an epoxy resin, (C) a curing agent and (D) a curing catalyst and various additives as required, and melt-mixing them. Can do. Melt mixing may be a known method, for example, the above components are charged into a reactor and melt mixed in a batch system, or the above components are put into a kneader such as a kneader or a hot three roll to continuously The method of melt-mixing can be mentioned.

  It is also possible to use the molten mixture obtained by injecting the molten mixture into a mold at a predetermined temperature after being B-staged and solidified.

The mode of sealing the light emitting semiconductor with the composition of the present invention is not particularly limited. For example, the light emitting semiconductor disposed in the housing having the opening is covered, and the housing is filled with the composition and cured. And can be sealed. In addition, an LED mounted on a matrix substrate can be sealed by a printing method, transfer molding, injection molding, compression molding, or the like. When a light-emitting semiconductor element such as an LED is coated by potting or injection, the composition of the present invention is preferably in a liquid state, and a measured value by a rotational viscometer at 25 ° C. is preferably 10 to 1,000,000 mPa · s. Is preferably about 100 to 1,000,000 mPa · s. On the other hand, when manufacturing a light emitting semiconductor device by transfer molding, etc., the above liquid resin can be used, but after thickening the liquid resin to solidify (B stage), pelletize, It can also be manufactured by molding.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

< Comparative synthesis example 1: (A) Synthesis of branched silicone resin>
After charging 112.71 g (0.908 mol) of Celoxide-2000 (manufactured by Daicel Chemical Industries), 208 ml of toluene, and a 2% octyl alcohol solution of chloroplatinic acid (Pt amount 20 ppm) in a reaction vessel, the following formula (a) 100 g (0.303 mol) of organopolysiloxane (n = 1) and 61 ml of toluene were added dropwise, and the mixture was heated to reflux for 16 hours.
After completion of the reaction, toluene was removed under reduced pressure, followed by filtration to obtain the desired resin (Resin 1). The epoxy equivalent of resin 1 was 262 g / eq.

上式（ａ）で表されるオルガノポリシロキサンの^１Ｈ−ＮＭＲ(３００ＭＨｚ, ＣＤＣｌ_３)では、０．３８ｐｐｍ、４．９８ｐｐｍ（Ｓｉ−Ｈ）、７．５０ｐｐｍ、及び７．７５ｐｐｍにピークが観察された。一方、樹脂１の^１Ｈ−ＮＭＲ(３００ＭＨｚ, ＣＤＣｌ_３)では、０．０９ｐｐｍ、０．５１ｐｐｍ、１．１５ｐｐｍ、１．２９ｐｐｍ、２．１２ｐｐｍ、３．１２ｐｐｍ、及び７．２４ｐｐｍにピークが観察され、末端に脂環式エポキシ基が結合されていることを確認した。また、樹脂１の^２９Ｓｉ−ＮＭＲ(６０ＭＨｚ, ＣＤＣｌ_３)では、−７６〜−８０ｐｐｍ（ＰｈＳｉＯ_3/2）、及び８〜１１ｐｐｍ（Ｍｅ_２ＳｉＯ）にピークが観察され、縮合反応により調製される樹脂で通常観察されるアルコキシ基が存在しないことを確認した。

In ¹ H-NMR (300 MHz, CDCl ₃ ) of the organopolysiloxane represented by the above formula (a), peaks are observed at 0.38 ppm, 4.98 ppm (Si—H), 7.50 ppm, and 7.75 ppm. It was done. On the other hand, in ¹ H-NMR (300 MHz, CDCl ₃ ) of resin 1, peaks are observed at 0.09 ppm, 0.51 ppm, 1.15 ppm, 1.29 ppm, 2.12 ppm, 3.12 ppm, and 7.24 ppm. It was confirmed that an alicyclic epoxy group was bonded to the terminal. Further, in ²⁹ Si-NMR (60 MHz, CDCl ₃ ) of resin 1, peaks are observed at −76 to −80 ppm (PhSiO _3/2 ) and 8 to 11 ppm (Me ₂ SiO), and the resin 1 is prepared by a condensation reaction. It was confirmed that there were no alkoxy groups normally observed in the resin.

<Synthesis Example 2: (A) Synthesis of Branched Silicone Resin>
A reaction vessel was charged with 74.51 g (0.600 mol) of Celoxide-2000 (manufactured by Daicel Chemical Industries), 150 ml of toluene, and a 2% octyl alcohol solution of chloroplatinic acid (Pt amount 20 ppm), and then the above formula (a) 161 g (0.200 mol) of organopolysiloxane (n = 5) and 40 ml of toluene were added dropwise, and the mixture was heated to reflux for 16 hours. After completion of the reaction, toluene was removed under reduced pressure, and filtration was performed to obtain the desired resin (resin 2). The epoxy equivalent of resin 2 was 546 g / eq.

<Synthesis Example 3: (A) Synthesis of Branched Silicone Resin>
A reaction vessel was charged with 74.51 g (0.600 mol) of Celoxide-2000 (manufactured by Daicel Chemical Industries), 150 ml of toluene, and a 2% octyl alcohol solution of chloroplatinic acid (Pt amount 20 ppm), and then the above formula (a) 520 g (0.200 mol) of organopolysiloxane (n = 10) and 100 ml of toluene were added dropwise, and the mixture was heated to reflux for 16 hours. After completion of the reaction, toluene was removed under reduced pressure, followed by filtration to obtain the desired resin (Resin 3). The epoxy equivalent of the resin 3 was 1023 g / eq.

< Comparative Synthesis Example 4: (A) Synthesis of Branched Silicone Resin>
After charging 99.35 g (0.800 mol) of Celoxide 2000 (manufactured by Daicel Chemical Industries, Ltd.), 180 ml of toluene, and a 2% octyl alcohol solution of chloroplatinic acid (Pt amount 20 ppm) into a reaction vessel, the following formula (b) The organopolysiloxane 84g (0.200 mol) represented by these and 40 ml of toluene were dripped, and it heated and refluxed. After completion of the reaction, toluene was removed under reduced pressure, followed by filtration to obtain the desired resin (resin 4). The epoxy equivalent of Resin 4 was 269 g / eq.

上式（ｂ）で表されるオルガノポリシロキサンの^１Ｈ−ＮＭＲ(３００ＭＨｚ, ＣＤＣｌ_３)では、０．３１ｐｐｍ、４．８５ｐｐｍ（Ｓｉ−Ｈ）、７．３９ｐｐｍ、７．７６ｐｐｍにピークが観察された。一方、樹脂４の^１Ｈ−ＮＭＲ(３００ＭＨｚ, ＣＤＣｌ_３)では、０．０２ｐｐｍ、０．４３ｐｐｍ、１．０７ｐｐｍ、１．５３ｐｐｍ、１．９０ｐｐｍ、２．０６ｐｐｍ、３．１０ｐｐｍ、７．１７ｐｐｍにピークが観察され、末端に脂環式エポキシ基が結合されていることを確認した。樹脂４の^２９Ｓｉ−ＮＭＲ(６０ＭＨｚ, ＣＤＣｌ_３)では、−７４〜−８３ｐｐｍ（ＰｈＳｉＯ_3/2）、７〜１１ｐｐｍ（Ｍｅ_２ＳｉＯ）にピークが観察され、縮合反応により調製される樹脂で通常観察されるアルコキシ基が存在しないことを確認した。

In ¹ H-NMR (300 MHz, CDCl ₃ ) of the organopolysiloxane represented by the above formula (b), peaks were observed at 0.31 ppm, 4.85 ppm (Si—H), 7.39 ppm, and 7.76 ppm. It was. On the other hand, ¹ H-NMR (300 MHz, CDCl ₃ ) of Resin 4 has peaks at 0.02 ppm, 0.43 ppm, 1.07 ppm, 1.53 ppm, 1.90 ppm, 2.06 ppm, 3.10 ppm, 7.17 ppm. Was observed, and it was confirmed that an alicyclic epoxy group was bonded to the terminal. In ²⁹ Si-NMR (60 MHz, CDCl ₃ ) of resin 4, peaks are observed at −74 to −83 ppm (PhSiO _3/2 ) and 7 to 11 ppm (Me ₂ SiO), and are usually prepared by a condensation reaction. It was confirmed that there were no observed alkoxy groups.

<Comparative Synthesis Example 5: Preparation of branched silicone resin by condensation reaction>
In a reaction vessel, MeO (Me) ₂ SiO (Me ₂ SiO) _n Si (Me) ₂ OMe (n = about 1.5) 596.82 g (2.10 mol), phenyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd.) (KBM103) 95.34 g (0.70 mol) and 1250 ml of isopropyl alcohol were charged, 21.75 g of a 25% aqueous solution of tetramethylammonium hydroxide and 195.75 g of water were added, and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, 1250 ml of toluene was put into the system and neutralized with an aqueous sodium dihydrogen phosphate solution. The residue was washed with hot water using a separatory funnel. Toluene was removed under reduced pressure to obtain an oligomer. Further, 517.44 g (2.10 mol) of 3- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (KBM303, Shin-Etsu Chemical Co., Ltd.) and 600 ml of isopropyl alcohol were added to the oligomer, and then tetramethylammonium hydroxide was added. 21.75 g of 25% aqueous solution and 195.75 g of water were added, and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, 1250 ml of toluene was put into the system and neutralized with an aqueous sodium dihydrogen phosphate solution. The residue was washed with hot water using a separatory funnel. Toluene was removed under reduced pressure to obtain the desired resin (referred to as “resin 5”). The epoxy equivalent of resin 5 was 441 g / eq.
Further, in ²⁹ Si-NMR (60 MHz, CDCl ₃ ) of Resin 5, −64 to −56 ppm (PhSiO _3/2 ), −52 to −44 ppm (fully condensed T unit Si portion), −41 to −36 ppm (alkoxy) Peaks were observed at the contained T unit Si portion), -4 to 3 ppm (fully condensed D unit Si portion), and 6 to 10 ppm (alkoxy containing D unit Si portion), and it was confirmed that an alkoxy group remained.

A composition was prepared using the obtained resin and the following components.
(B) Epoxy resin: (3,4-epoxycyclohexane) methyl 3 ′, 4′-epoxycyclohexylcarboxylate (Celoxide 2021P, manufactured by Daicel Industries, Ltd.)
(C) Hardener: Methylhexahydrophthalic anhydride (MH, manufactured by Shin Nippon Rika Co., Ltd.)
(D) Curing catalyst: Organic phosphonium salt (UCAT-5003, manufactured by San Apro Co., Ltd.)
Adhesion aid: 3-mercaptopropylmethyldimethoxysilane (KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.)

<Examples 2 and 3 and Comparative Examples 1 to 3 >
A composition was prepared according to the formulation (parts by mass) shown in Table 1.
The obtained composition was subjected to post-cure at 100 ° C. for 2 hours and further at 150 ° C. for 4 hours to obtain a bar-shaped cured product having a thickness of 5 mm. Using this rod-shaped cured product, the appearance, bending elastic modulus and bending strength (JIS K-6911), and the appearance after the light resistance test were evaluated. In the light resistance test, the transmittance after 12 hours of UV irradiation (high pressure mercury lamp 30 mW / cm ² , 365 nm) when the transmittance at the initial 400 nm was 100% was determined. Further, the viscosity ratio after storage at 23 ° C./8 hr to the initial viscosity at 23 ° C. was measured. The results are shown in Table 1.

Using the compositions of LED device Examples 2 and 3 and Comparative Example 1, three LED devices were prepared by the following method. An InGaN-based blue light-emitting element was fixed with a silver paste on a pre-molded package for LED having a thickness of 1 mm, a side of 3 mm, an opening of 2.6 mm in diameter, and a bottom of which was silver-plated. Next, the external electrode and the light emitting element were connected by a gold wire. Each composition was injected into the package opening. It was cured at 100 ° C. for 1 hour and further at 150 ° C. for 2 hours to produce an LED device. Using the created LED device, a temperature cycle test under the following conditions and an LED lighting test at 65 ° C./95% RH for 3000 hours were performed, and the adhesion failure of the package interface, the presence of cracks, and the presence or absence of discoloration were visually observed. . The results are shown in Table 2.

As can be seen from Table 1, in the composition of Comparative Example 1 containing the resin 5 obtained by the condensation reaction, the increase in viscosity was remarkable. Further, as can be seen from Table 2, the package obtained from the composition of Comparative Example 1 was inferior in thermal shock resistance and light resistance as compared with the cured products obtained from the compositions of Examples.

The composition for sealing an optical semiconductor element of the present invention has a long pot life and is useful for forming an optical semiconductor device excellent in light resistance and thermal shock resistance.

Claims (4)

The composition for optical semiconductor element sealing containing following (A), (B), (C) and (D).
(A) an unsaturated group-containing epoxy compounds and addition reaction is prepared from the following equation with the organopolysiloxane having a SiH group (2) branched silicone resins to 100 parts by mass of Ru indicated by

[Monovalent aryl groups for ^{R 1} is _{C 6-20,} ^{R 2} and ^{R 3} _are each independently a monovalent alkyl or aryl group of _{C 1-20,} monovalent ^{R 4} is _{C 1-20} alkyl group or an epoxy group-containing group, provided that are three or more epoxy group-containing group der of ^{R 4} in one molecule, p, q, and r are an integer of 1 to 20, s is from 1 to 5 integer der Ru]
(B) Alicyclic epoxy resin having two or more epoxy groups per molecule (A) Component and (B) 50 parts by mass or less (C) Curing agent (A) component with respect to 100 parts by mass in total (B) Amount of the epoxy group and reactive group to be 0.4 to 1.5 mol with respect to 1 mol of the total epoxy group of component (D) Curing catalyst (A) Component, (B) component and (C ) 0.01-3 parts by mass with respect to 100 parts by mass in total of the components The composition according to claim 1, wherein R ¹ is a phenyl group, R ² and R ³ are methyl groups, and the epoxy group-containing group is a β- (3,4-epoxycyclohexyl) ethyl group. (C) The composition according to claim 1 or 2, wherein the curing agent is an acid anhydride. The composition according to any one of claims 1 to 3 , further comprising a mercapto-based silane coupling agent.