JP6966902B2 - A heat-resistant condensation-curable silicone resin composition and an optical semiconductor device using the same. - Google Patents

Description

The present invention relates to a heat-resistant, heat-resistant silicone resin composition that has heat resistance, does not deteriorate even when left at a high temperature for a long period of time, and does not generate cracks, and an optical semiconductor device using the same.

Conventionally, a silanol condensation catalyst, a heat-curable silicone resin composition for encapsulating an optical semiconductor, and an optical semiconductor encapsulant using the silanol condensation catalyst, which has excellent heat-resistant coloring stability and thin film curability and can suppress heat loss, have been proposed. (Patent Document 1). The silicone resin composition has (A) 100 parts by mass of a polysiloxane having two or more silanol groups in one molecule, and (B) two or more alkoxy groups bonded to a silicon atom in one molecule. A heat-curable opto-semiconductor-encapsulating silicone resin composition containing 0.1 to 2000 parts by mass of a silane compound and (C) a zirconium metal salt represented by the formula (I) in Patent Document 1.

However, the silicone resin composition may deteriorate when left at a high temperature of about 250 ° C. for a long time and cracks may occur in the cured product, and is used as a sealing agent for an optical semiconductor device (hereinafter referred to as LED). Then, there is a problem that the brightness of the LED may decrease.

Japanese Unexamined Patent Publication No. 2010-163602

The problem to be solved by the present invention is that it has heat resistance and does not deteriorate and cracks do not occur even when it is left at a high temperature for a long time. As a result, when it is used as an LED encapsulant, the brightness of the LED is lowered. It is an object of the present invention to provide a condensation-curable silicone resin composition having less heat resistance and an optical semiconductor device using the same.

In order to solve the above-mentioned problems, the invention according to claim 1 combines an organopolysiloxane (A) having at least two hydrolyzable groups bonded to a silanol group or a silicon atom to a silicon atom in one molecule. As a silane compound (B) having two or more alkoxy groups, a silanol condensation catalyst (C), and a heat resistance imparting agent (D),
Organopolysiloxane (D1) with a viscosity of 10 to 10000 mPa · s at 25 ° C.
General formula (R ₁ COO) _n M (R ₁ is a monovalent hydrocarbon group of the same kind or a different kind, M is a mixture of rare earth elements containing cerium as a main component, n = 3 or 4). D2) and
A titanium compound (D3) represented by the general formula (R ₂ O) ₄ Ti (R ₂ is a monovalent hydrocarbon group of the same type or a different type) is used.
Rare earth-containing organopolysiloxane compounds obtained by heat treatment at a temperature of 250 ° C or higher, and
Only including,
It is characterized by containing 0.2 to 5 parts by weight of the heat resistance imparting agent (D) with respect to 100 parts by weight of the organopolysiloxane (A) having at least two hydrolyzable groups bonded to a silanol group or a silicon atom. Provided is a condensation-curable silicone resin composition having heat resistance.

The invention according to claim 2 provides an optical semiconductor device characterized in that the optical semiconductor element is sealed with the cured product of claim 1.

The heat-resistant condensation-curable silicone resin composition of the present invention has the effect that the physical properties do not deteriorate even when left at a high temperature for a long time and cracks do not occur, and as a result, the brightness of the LED decreases. There is no effect. Further, the optical semiconductor device according to claim 2 has an effect that the brightness does not decrease as a result.

Hereinafter, the heat-resistant condensation-curable silicone resin composition according to the present invention will be specifically described.

<Polydimethylsiloxane (A) whose molecular chain end is sealed with a hydroxyl group>
The organopolysiloxane (A) having at least two hydrolyzable groups bonded to a silanol group or a silicon atom used in the present invention imparts appropriate fluidity to the present composition before curing, and rubber after curing. It is formulated to give excellent mechanical properties to the elastic body, and it is desirable that the viscosity at 25 ° C. is 0.01 to 1000 Pa · s. If the viscosity is less than 0.01 Pa · s, the mechanical properties of the rubber-like elastic body after curing become insufficient, and if it exceeds 1000 Pa · s, it becomes difficult to obtain a uniform composition and the fluidity deteriorates. The more preferable viscosity at 25 ° C. is 0.1 to 100 Pa · s, and if it is less than 0.1 Pa · s, the mechanical properties of the rubber-like elastic body after curing tend to be insufficient, and if it exceeds 100 Pa · s, it is uniform. The composition tends to be difficult to obtain, and the fluidity tends to be poor. Examples of the hydrolyzable group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and a methoxyethoxy group.

As the organic group directly bonded to the silicon atom, a methyl group is preferable because of ease of synthesis, but other alkyl groups such as methyl, ethyl, propyl, butyl and hexyl, alkenyl groups such as vinyl and allyl, and chloromethyl A monovalent substituted hydrocarbon group such as a group, a β-cyanoethyl group, or a 3,3,3-trifluoropropyl group may be bonded.

In particular, the methyl group not only obtains the raw material intermediate most easily, but also has a low viscosity even if the degree of polymerization of siloxane is high, and balances the fluidity of the present composition before curing and the physical properties of the rubber-like elastic body after curing. Is good. Even when the other organic groups are bonded, it is preferable that 85% or more of all the organic groups are methyl groups.

<Silane compound (B) having two or more alkoxy groups bonded to silicon atoms in one molecule>
The silane compound (B) used in the present invention having two or more alkoxy groups bonded to a silicon atom in one molecule has one silicon atom in one molecule, and the silicon atom has two alkoxy groups. In addition to compounds having two or more bonds, an organopolysiloxane compound having two or more silicon atoms in one molecule, a polysiloxane skeleton, and two or more alkoxy groups bonded to silicon atoms. Either may be used, but the former silane compound (B) is preferable.

Examples of the silane compound having one silicon atom in one molecule and having two or more alkoxy groups bonded to the silicon atom include dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, and diethyldiethoxysilane. Dialkoxysilanes such as diphenyldimethoxysilane, diphenyldiethoxysilane; trialkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane Tetraalkoxysilanes such as tetramethoxysilanes, tetraethoxysilanes, tetraisopropyloxysilanes; hydrolysates of trialkoxysilanes, tetraalkoxysilanes; γ- (meth) acryloxypropyltrimethoxysilanes, γ- (meth) acrylics. (Meta) acryloxyalkyltrialkoxysilanes such as loxypropyltriethoxysilane can be mentioned.

<Silanol condensation catalyst (C)>
The silanol condensation catalyst (C) used in the present invention is tin octylate, tin neodecanoate, tin naphthenate, tin stearate, dibutyltin dioctate, dibutyltin dilaurate, dioctyltin diversatete, dibutyltin bistriethoxysilicate, dibutyltin dio. Railmalate, dibutyltin diacetate, 1,1,3,3-tetrabutyl-1,3-dilauryloxycarbonyl-distanoxane, dibutyltin oxybisethoxysilicate, dibutyltin oxide, dioctyl tin salt and ethyl orthosilicate Reaction products, reaction products of dibutyltin salt and ethyl orthosilicate, reaction products of dibutyltin oxide and phthalate ester, reaction products of dibutyltin oxide and maleic acid diester, dibutyltin diacetylacetonate, etc. Examples include organic tin compounds. By using such a silanol condensation catalyst (C), the internal curability of the present composition becomes good.

The blending amount of (C) of the silanol condensation catalyst is 0.1 to 1.0 part by weight with respect to 100 parts by weight of the component (A), and if it is less than 0.1 part by weight, the curing rate may be slowed down. If it exceeds 0.0 parts by weight, the pot life may be shortened. As a commercially available tin stearate, there is Neostan U-50 (manufactured by Nitto Kasei Co., Ltd., trade name).

<Heat resistance imparting agent (D)>
The heat-resistant imparting agent (D) used in the present invention is an organopolysiloxane (D1) having a viscosity at 25 ° C. of 10 to 10000 mPa · s and a general formula (R ₁ COO) _n M (R ₁ is the same or different species). monovalent hydrocarbon radical, M is a rare earth element mixture composed mainly of cerium, a carboxylate of cerium (D2) represented by n = 3 or 4), the general formula _{(R 2 O) 4 Ti (} R 2 is It is a rare earth-containing organopolysiloxane compound obtained by heat-treating a titanium compound (D3) represented by the same or different monovalent hydrocarbon group) at a temperature of 250 ° C. or higher.

The organopolysiloxane (D1) may be any conventionally known organopolysiloxane having a viscosity at 25 ° C. of 10 to 10,000 mPa · s, which is substantially composed of repeating diorganopolysiloxane units (linear structure). It is a linear or branched type that keeps the liquid at room temperature. The organic group bonded to the silicon atom (that is, an unsubstituted or substituted monovalent hydrocarbon group) is specifically an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group; a vinyl group or an allyl group. Alkenyl groups such as alkenyl groups; aryl groups such as phenyl groups and trill groups; cycloalkyl groups such as sirokuhexyl groups; or groups in which part or all of the hydrogen atoms bonded to these carbon atoms are substituted with halogen atoms, cyano groups, etc. For example, it is selected from a chloromethyl group, a fluoropropyl group, a cyanomethyl group and the like. The organopolysiloxane (D1) has a trialkylsiloxy group such as a trimethylsiloxy group, an alkenyldialkylsiloxy group such as a vinyldimethylsiloxy group, a dialkenylalkylsiloxy group such as a divinylmethylsiloxy group, and trivinyl having a molecular chain terminal thereof. Examples thereof include those that are sealed with a triorganosyloxy group such as a trialkenyl syroxy group such as a syroxy group, a hydroxyl group, an alkoxy group or the like. Further, it may be a mixture of these various organopolysiloxanes. The viscosity of the organopolysiloxane (D1) component is 10 to 10000 mPa · s, preferably 50 to 1000 mPa · s at 25 ° C. When the viscosity is 10 mPa · s or less, the amount of siloxane evaporation at a high temperature tends to be large, and the weight change becomes large, so that the heat resistance tends to decrease. Further, when it exceeds 10,000 mPa · s, miscibility with the cerium compound described later is not smoothly performed, so that the heat resistance also tends to decrease.

The carboxylic acid salt of cerium as a component (D2) has a general formula:
(R ₁ COO) _n M
In this case, R ₁ is a monovalent hydrocarbon group of the same kind or a different kind, and M is a rare earth element mixture containing cerium as a main component, which is 2-ethylhexanoic acid, naphthenic acid, oleic acid, lauric acid, and stearic acid. Examples are cerium salts such as acids. The carboxylate of cerium is preferably used as an organic solvent solution because of its ease of handling and compatibility with titanium as the component (D3) below. As this organic solvent, standard solvent and the like are used. Examples thereof include petroleum-based solvents such as mineral spirit, ligroin, and petroleum ether, and aromatic solvents such as toluene and xylene.

The amount of the component (D2) added is polydimethyl in which the molecular chain end of the component constituting the condensation-curable silicone resin composition containing the heat-resistant imparting agent of the present invention is sealed with a hydroxyl group. The amount is 0.05 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the siloxane (A). If the amount of cerium is less than 0.05 parts by weight, the expected heat resistance cannot be obtained. Further, when the amount is more than 5 parts by weight, the cerium compound becomes non-uniform in the polydimethylsiloxane (A) component, and the predetermined heat resistance cannot be obtained.

The titanium compound as a component (D3) has a general formula:
(R ₂ O) ₄ Ti
Indicated by. Here, _{each of R 2} is an independently monovalent hydrocarbon group, preferably an alkyl having 1 to 30 carbon atoms such as an isopropyl group, an n-butyl group, a stearyl group, and an octyl group, preferably 1 to 20 carbon atoms. It is a group, and Ti is titanium. Examples of such a compound are tetraalkoxytitanium, but the compound may be a partially hydrolyzed condensate thereof.

The heat resistance imparting agent (D) according to the present invention is obtained by mixing the above components (D1) to (D3) and then heat-treating at a temperature of 250 ° C. or higher, but the heating temperature thereof is less than 250 ° C. In this case, it is difficult to obtain a uniform composition, and if the temperature exceeds 310 ° C., the thermal decomposition rate of the component (D1) increases, so that the treatment is preferably performed at 250 to 310 ° C.

The heat resistance-imparting agent of the present invention is 0.2 to 0.2 to 100 parts by weight of polydimethylsiloxane (A) whose molecular chain end is sealed with a hydroxyl group, which is a component constituting the condensation-curable silicone resin composition. It is preferable to add 5 parts by weight, and more preferably 0.5 to 4 parts by weight. When the amount of the heat resistance imparting agent added according to the present invention is less than 0.2 parts by weight, the effect of improving the heat resistance at high temperature is not seen, and conversely, when the amount exceeds 5 parts by weight, the heat resistance is improved at high temperature. It becomes difficult to obtain the effect of.

The structure of the rare earth-containing organopolysiloxane compound is that the cerium carboxylate (D2) before heat treatment is a carboxylate of a mixture of rare earth elements containing cerium as a main component, and the rare earth-containing organopoly obtained by heat treatment. Since the siloxane compound is not a single substance, it is difficult to isolate and identify each of them even for trace components, and it is impossible to identify them by their structure. Further, it is difficult to separate the rare earth-containing organopolysiloxane compound as a mixture, and it is impossible to directly specify the rare earth-containing organopolysiloxane compound obtained by the heat treatment by its characteristics. Therefore, with respect to the rare earth-containing organopolysiloxane compound, there are circumstances in which it is impossible or approximately impractical to "directly specify the substance by its structure or characteristics at the time of filing."

<Silicone oil>
Silicone oil can be added to the present invention if necessary. Silicone oil is blended for the purpose of improving workability when using this composition, improving foam removal property, etc., and adjusting the hardness and elongation of the rubber-like elastic body after curing. The silicone oil is a non-reactive silicone oil having no reactive group such as an alkoxy group or a silanol group in the molecule, and the end of the molecular chain is sealed with a triorganosyloxy group such as a trimethylsiloxy group. Most preferably used is polydimethylsiloxane with both ends sealed with a trimethylsiloxy group.

The viscosity of the silicone oil is preferably 5 to 50,000 mPa · s at 25 ° C., and if it is less than 5 mcSt, the mechanical properties of the rubber-like elastic body after curing of the present composition may be insufficient. If it exceeds 000 mPa · s, the fluidity of the present composition may deteriorate. More preferably, it is 50 to 5,000 mP · s, and if it is less than 50 mP · s, the mechanical properties of the rubber-like elastic body after curing of the present composition tend to be insufficient, and if it exceeds 5,000 mPa · s, the book The extruding workability of the composition tends to deteriorate.

The blending amount of the silicone oil is 0.1 to 100 parts by weight, preferably 0.2 to 80 parts by weight, per 100 parts by weight of the component (A). If it is less than 0.1 part by weight, the fluidity of the present composition becomes insufficient, and if it exceeds 100 parts by weight, the mechanical strength of the cured product decreases. If it is less than 0.2 parts by weight, the extrusion workability of the present composition tends to be insufficient, and if it exceeds 80 parts by weight, the mechanical strength of the cured product tends to decrease.

In the optical semiconductor device according to claim 2 of the present invention, an optical semiconductor element such as an optical semiconductor (LED) is sealed with a cured product of the condensation-curable silicone resin composition having heat resistance according to claim 1. It is an optical semiconductor device.

Hereinafter, a specific description will be given with reference to Examples and Comparative Examples.

<Preparation of heat resistance imparting agent (D)>
As an organopolysiloxane (D1) having a viscosity at 25 ° C. of 10 to 10,000 mPa · s, a linear dimethylpolysiloxane having a viscosity of 100 mP · s / 25 ° C. with both ends sealed with a trimethylsiloxy group was used. As the carboxylate of cerium (D2), a turpentine solution of 2-ethylhexanoic acid rare earth rare earth OCTOATE 6% (rare earth element content 6% by weight, manufactured by DIC) was used as a titanium compound (D3). Using normal butoxide (titanium content 14% by weight), the components (D2) and (D3) were mixed in the formulation shown in Table 1, and the mixed solution was added to the component (D1) with stirring. After that, the turpen was volatilized by heating while flowing nitrogen gas. Subsequently, the mixture was heated at 300 ° C. for 1 hour with stirring to prepare a brown and transparent heat-resistant imparting agent (D).

<Examples and comparative examples>
In the formulation shown in Table 2, polydimethylsiloxane having both ends of the molecular chain having a viscosity of 3 Pa · s / 25 ° C. sealed with hydroxyl groups was used as the component (A), and tetraethoxysilane was used as the silane compound (B). As the silicone oil, polydimethylsiloxane having a viscosity of 0.1 Pa · s / 25 ° C. and both ends sealed with a trimethylsiloxy group is used, and as a silanol condensation catalyst (C), Neostan U-50 (manufactured by Nitto Kasei Co., Ltd., trade name) ), And as the heat resistance imparting agent (D), the heat resistance imparting agent (D) prepared as described above is used, and all the materials are uniformly mixed and the condensation curing type of Example or Comparative Example. A silicone resin composition was obtained.

<Evaluation items and evaluation methods>

<Durometer hardness>
The condensation-curable silicone resin compositions of Examples and Comparative Examples are poured into a container having a diameter of 3 cm and left to stand in a container at 23 ° C. and 50% RH for 7 days to prepare a cured product having a thickness of 10 mm. This hardness was measured by a type A durometer specified in JIS K 6253 and used as the initial durometer hardness. Then, the cured product was left in an oven at 250 ° C. for 100 hours and 200 hours, and after each time elapsed, the cured product was slowly cooled to 23 ° C., and the durometer hardness was measured in the same manner.

<Weight change rate>
The condensation-curable silicone resin compositions of Examples and Comparative Examples are poured into a container having a diameter of 3 cm and left to stand in a container at 23 ° C. and 50% RH for 7 days to prepare a cured product having a thickness of 10 mm. This weight is measured and used as the initial weight. Then, the cured product is left in an oven at 250 ° C. for 100 hours and 200 hours, slowly cooled to 23 ° C. after each time elapses, weighed and used as the weight after heating. The weight change rate (%) was calculated by dividing the value obtained by subtracting the initial weight from the weight after heating by the initial weight.

<Crack>
The condensation-curable silicone resin compositions of Examples and Comparative Examples are poured into a container having a diameter of 3 cm and left to stand in a container at 23 ° C. and 50% RH for 7 days to prepare a cured product having a thickness of 10 mm. Then, the cured product was left in an oven at 250 ° C. for 100 hours and 200 hours, and after each time elapsed, it was visually confirmed whether or not cracks were generated in the cured product.

<Evaluation result>
The evaluation results are shown in Table 3.

Claims (2)

An organopolysiloxane (A) having at least two hydrolyzable groups bonded to a silanol group or a silicon atom, and a silane compound (B) having two or more alkoxy groups bonded to a silicon atom in one molecule. As a silanol condensation catalyst (C) and a heat resistance imparting agent (D),
Organopolysiloxane (D1) with a viscosity of 10 to 10000 mPa · s at 25 ° C.
General formula (R ₁ COO) _n M (R ₁ is a monovalent hydrocarbon group of the same kind or a different kind, M is a mixture of rare earth elements containing cerium as a main component, n = 3 or 4). D2) and
A titanium compound (D3) represented by the general formula (R ₂ O) ₄ Ti (R ₂ is a monovalent hydrocarbon group of the same type or a different type) is used.
Rare earth-containing organopolysiloxane compounds obtained by heat treatment at a temperature of 250 ° C or higher, and
Only including,
It is characterized by containing 0.2 to 5 parts by weight of the heat resistance imparting agent (D) with respect to 100 parts by weight of the organopolysiloxane (A) having at least two hydrolyzable groups bonded to a silanol group or a silicon atom. A condensation-curable silicone resin composition having heat resistance. An optical semiconductor device according to claim 1, wherein the optical semiconductor element is sealed with the cured product.