JP2010120984A - Flame-retardant polyorganosiloxane composition for sealing electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a room temperature curable polyorganosiloxane composition that has excellent curability and flame retardance, a sufficient operation pot life, low hardness of cured product, has excellent adhesiveness to various substrates and is useful for sealing electronic components. <P>SOLUTION: The room temperature curable polyorganosiloxane composition comprises a main agent component (A) composed of (a1) a polyorganosiloxane containing both molecular chain terminals blocked with hydroxy groups and having a viscosity (23°C) of 0.02-100 Pa s, (a2) a flame retardance imparting filler, (a3) a silica-based filler and (a4) a platinum composition being a flame retardance imparting agent and a curing agent component (B) composed of (b1) an alkoxy silane and/or a hydrolysis-condensation product thereof, (b2) an amino group-substituted alkoxysilane and (b3) a curing catalyst in the mixing ratio of the main agent component (A) to the curing agent component (B) of 100:0.6 to 100:12 by weight. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flame retardant polyorganosiloxane composition that cures at room temperature to produce a rubbery elastic body, and more particularly to a two-component flame retardant polyorganosiloxane composition for encapsulating electronic components.

  Condensation-reactive polyorganosiloxane compositions that cure at room temperature to produce rubbery elastic bodies are used as elastic adhesives, coating materials, electrical insulating sealing materials, etc. in the electrical and electronic industries, and as building sealing materials, etc. Widely used.

  Among the condensation reaction type room temperature curable polyorganosiloxane compositions, one-component type (one package type) in which a curing reaction occurs by contact with moisture in the air, the base polymer and the crosslinking agent immediately before use There is no need to weigh or mix the catalyst and the catalyst, and the handling is easy. However, since curing proceeds gradually from the surface to the inside, there are drawbacks that the curing rate is slow and the deep-curability is poor.

  On the other hand, the two-component room temperature curable polyorganosiloxane composition has a high curing rate and better deep part curability than the one-component type. This composition is generally prepared as a main component and a curing agent component (crosslinking component), and is used as a so-called multi-packaging room temperature curable composition that is stored in separate containers and mixed at the time of use. The main component is blended with an inorganic filler together with a polydiorganosiloxane whose molecular terminal is a base polymer blocked with a hydroxyl group and / or an alkoxy group, and the curing agent component is blended with a crosslinking agent and a curing catalyst (for example, , See Patent Document 1).

  However, conventional one-component and two-component room temperature curable polyorganosiloxane compositions are not sufficient in fluidity and flame retardancy, such as fluidity, flame retardancy, discharge workability, and hardness after curing. None of them satisfy all the characteristics required as potting materials for sealing electronic parts.

  For example, as a potting material for solar cell panel terminals, it has good flame retardancy, good fluidity to reduce the generation of voids in narrow gaps, and avoids hardening inside a stirrer etc. Therefore, it is required to have a sufficient discharge property. In addition, adhesion to various base materials is not sufficient, especially those added with zinc carbonate or aluminum hydroxide to impart flame retardancy, because the rubber hardness increases with the increase in the amount of filler, further adhesion There was a problem that decreased.

In addition, in order to relieve stress at the time of work shrinkage after potting and have a suitable working life, a material that provides a cured product with low hardness is required. At present, no satisfactory room temperature curable polyorganosiloxane composition has been obtained.
JP 2005-105235 A

  The present invention has been made in order to solve such problems of the prior art, has good curability and flame retardancy, has a sufficient working life, and has a low hardness and various bases. An object of the present invention is to provide a room temperature-curable polyorganosiloxane composition having excellent adhesion to a material.

The flame-retardant polyorganosiloxane composition for sealing electronic parts of the present invention comprises (a1) a polyorganosiloxane having a molecular chain both ends blocked with hydroxyl groups and a viscosity at 23 ° C. of 0.02 to 100 Pa · s; (A2) a flame retardant imparting filler, (a3) a silica-based filler, (a4) a main component (A) containing a platinum compound as a flame retardant imparting agent, and (b1) a general formula (1) _{^{): R 1 a Si (OR}} 2) 4-a ... (1)
Wherein R ¹ and R ² are unsubstituted monovalent hydrocarbon groups which may be the same or different, and a is an integer of 0, 1 or 2. And / or a hydrolysis condensate thereof, (b2) an amino group-substituted alkoxysilane, and (b3) a curing agent component (B) containing a curing catalyst, and the main component (A) and the curing agent component. The mixing ratio with (B) is 100: 0.6 to 100: 12 by weight.

  The flame-retardant polyorganosiloxane composition of the present invention has good fluidity, curability and flame retardancy, has a sufficient working life, and has a low hardness and adhesion to various substrates. Therefore, it is suitable as a potting material for sealing electronic parts such as for sealing terminal portions of solar cell panels.

  Hereinafter, embodiments of the present invention will be described.

  The main component which is the component (A) of the flame retardant polyorganosiloxane composition of the present invention is: (a1) a polyorganosiloxane having a viscosity at 23 ° C. of 0.02 to 100 Pa · s; and (a2) imparting flame retardancy. Each contains a filler, (a3) a silica-based filler, and (a4) a platinum compound.

The polyorganosiloxane as the component (a1) is a substantially linear polyorganosiloxane represented by the following general formula (2) in which both ends of the molecular chain are blocked with hydroxyl groups.

In the formula (2), a plurality of R ³ are substituted or unsubstituted monovalent hydrocarbon groups which may be the same or different from each other. R ³ includes methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, alkyl group such as dodecyl group; cycloalkyl group such as cyclohexyl group; vinyl group, allyl group An alkenyl group such as a group; an aryl group such as a phenyl group, a tolyl group and a xylyl group; an aralkyl group such as a benzyl group, a 2-phenylethyl group and a 2-phenylpropyl group; and a hydrogen atom of these hydrocarbon groups A halogenated alkyl group such as a chloromethyl group, a 3-chloropropyl group, or a 3,3,3-trifluoropropyl group substituted by another atom or group such as a halogen atom; Examples thereof include substituted hydrocarbon groups such as a cyanoalkyl group such as a propyl group. Of these, the synthesis is easy, the component (a1) has a low viscosity relative to the molecular weight, gives good extrudability to the composition before curing, and good physical properties to the composition after curing. Therefore, 85% or more of all organic groups are preferably methyl groups, and substantially all organic groups are more preferably methyl groups.

On the other hand, in particular, when imparting heat resistance, radiation resistance, cold resistance or transparency, a necessary amount of aryl group as a part of R ³ , and when imparting oil resistance and solvent resistance, R ³ When a 3,3,3-trifluoropropyl group or 3-cyanopropyl group is provided as a part, or a surface having paintability is provided, a long chain alkyl group or an aralkyl group is a methyl group as a part of R ^3. Can be arbitrarily selected depending on the purpose.

  In addition, the polyorganosiloxane that is the component (a1) has a viscosity at 23 ° C. of 0.02 to 100 Pa · s. Therefore, n in the formula (2) is the viscosity of the component (a1) at 23 ° C. A number (integer) in the range. If the viscosity at 23 ° C. of the component (a1) is less than 0.02 Pa · s, the rubber-like elastic body after curing is insufficiently stretched. Conversely, if it exceeds 100 Pa · s, workability such as dischargeability and flow characteristics Decreases. The preferred viscosity of the component (a1) is in the range of 0.1 to 50 Pa · s because the properties required for the composition before and after curing are harmonized.

  Such polyorganosiloxane is obtained, for example, by ring-opening polymerization or ring-opening copolymerization of a cyclic diorganosiloxane low monomer such as octamethylcyclotetrasiloxane in the presence of water with an acidic catalyst or an alkaline catalyst. be able to.

  The flame retardant imparting filler as the component (a2) imparts flame resistance to the composition and a rubber-like elastic body obtained by curing the composition, and imparts high mechanical strength to the cured product. Examples of such flame retardant imparting fillers include zinc carbonate, basic zinc carbonate, aluminum hydroxide, magnesium carbonate, titanium dioxide, cerium oxide, and those whose surfaces have been treated. These may be used individually by 1 type, and may mix and use 2 or more types. Of these, zinc carbonate and aluminum hydroxide are preferred from the viewpoint of imparting flame retardancy, and zinc carbonate is particularly preferred from the viewpoint of flow characteristics.

  The amount of the flame retardant imparting filler as component (a2) is 1 to 200 parts by weight, preferably 5 to 100 parts by weight, per 100 parts by weight of component (a1). If it is less than 1 part by weight, the flame retardancy is not sufficiently imparted. Conversely, if it exceeds 200 parts by weight, the mechanical properties and flow properties after curing are lowered.

  Examples of the silica-based filler that is the component (a3) include non-reinforcing fillers such as pulverized silica (quartz fine powder). In addition, in order to control the rate of the condensation reaction, it contains amorphous silica (precipitated silica) containing 3 to 12% by weight, preferably 5 to 10% by weight of water necessary for the progress of the reaction. Is preferred. Among the components (a3), the amount of pulverized silica is 10 to 200 parts by weight, preferably 20 to 100 parts by weight, based on 100 parts by weight of the component (a1). Moreover, the compounding quantity of a water-containing amorphous silica (precipitated silica) is 0.1-30 weight part with respect to 100 weight part of (a1) component, Preferably it is 0.5-10 weight part.

  The platinum compound as the component (a4) is a component added to further improve the flame retardancy of the rubbery elastic body obtained by curing the composition and the composition. Examples of such platinum compounds include chloroplatinic acid, alcohol-modified chloroplatinic acid, complexes of platinum and olefins, complexes of platinum and ketones, complexes of platinum and vinylsiloxane, and complexes of platinum and nitrile compounds. And a complex of phosphoric acid or phosphorous acid compound and platinum. These platinum compounds may be used individually by 1 type, and may be used in mixture of 2 or more types.

  The compounding amount of the (a4) platinum compound is 1 to 1000 ppm, more preferably 5 to 200 ppm, based on 100 parts by weight of the component (a1) as a platinum element. If it is less than 1 ppm, the flame retardancy cannot be sufficiently improved. Conversely, if it exceeds 1000 ppm, not only the effect can be obtained but also it is uneconomical.

  The curing component which is the component (B) of the flame retardant polyorganosiloxane composition of the present invention includes (b1) an alkoxysilane and / or a hydrolysis condensate thereof, (b2) an amino group-substituted alkoxysilane, (b3) Each contains a curing catalyst.

The component (b1) is a component that acts as a crosslinking agent for the component (a1). The alkoxysilane represented by the general formula (1): R ¹ _a Si (OR ² ) _4-a (1) and / or It is the hydrolysis condensate.

In formula (1), R ¹ and R ² are unsubstituted monovalent hydrocarbon groups which may be the same or different from each other, and include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, Alkyl group such as hexyl group, octyl group, decyl group, dodecyl group; cycloalkyl group such as cyclohexyl group; alkenyl group such as vinyl group and allyl group; aryl group such as phenyl group, tolyl group and xylyl group An aralkyl group such as benzyl group, 2-phenylethyl group, 2-phenylpropyl group; A is an integer of 0, 1 or 2.

  Examples of the component (b1) include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, vinyltrimethoxysilane, decyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, methyltri (ethoxymethoxy) silane, and dimethyl. Examples include dimethoxysilane, dimethyldiethoxysilane, and diphenyldimethoxysilane.

  The alkoxysilane and / or its hydrolysis condensate as component (b1) is blended in an amount of 0.1 to 50 parts by weight, preferably 0.5 to 25 parts by weight, per 100 parts by weight of component (a1). When the blending amount of component (b1) is less than 0.1 parts by weight, good curability cannot be obtained, and when it exceeds 50 parts by weight, rubber physical properties after curing (for example, hardness, tensile strength, elongation, etc.) ) May be adversely affected.

  The amino group-substituted alkoxysilane as the component (b2) is a component that acts as a crosslinking agent for the component (a1) and improves the adhesion as in the case of the component (b1). (B2) As the amino group-substituted alkoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxy Examples include silane, N- (β-aminoethyl) -γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, and the like. These compounds have the advantage of providing excellent storage stability as well as fast curability.

  The (b2) component amino group-substituted alkoxysilane is added in an amount of 0.5 to 50 parts by weight, preferably 3 to 30 parts by weight, per 100 parts by weight of the component (a1). When the compounding ratio of the component (b2) is out of the above range, the physical properties of rubber after curing (for example, hardness, tensile strength, elongation, etc.) are adversely affected. Further, the curability may be affected. For example, when the blending amount of the component (b2) exceeds 50 parts by weight, not only the curing rate is abnormally slow but also the deep part curability is deteriorated.

  Furthermore, in order to improve the adhesion and storage stability of the composition, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxy It is also possible to mix an epoxy group-containing alkoxysilane such as silane or β- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane.

The curing catalyst which is component (b3) is a catalyst which mainly promotes the condensation reaction between the hydroxyl group of component (a1) and the hydrolyzable group of component (b1) and component (b2), that is, the OR ² group. Examples of the component (b3) include iron octoate, manganese octoate, zinc octoate, tin naphthate, tin caprylate and tin oleate; carboxylic acid metal salts; dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin dioleate Organic tin compounds such as diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dioctyltin dilaurate; tetraethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium, 1,3-propoxytitaniumbis ( Alkoxytitanium such as ethyl acetylacetate; aluminum trisacetylacetonate, aluminum trisethylacetoacetate, dii Organic aluminum compounds such as sopropoxyaluminum ethyl acetoacetate and triethoxyaluminum; organic zirconium compounds such as zirconium tetraacetylacetonate, tetraisopropoxyzirconium, tetrabutoxyzirconium, tributoxyzirconium acetylacetonate, tributoxyzirconium stearate, etc. Is exemplified. These may be used individually by 1 type, and may mix and use 2 or more types. Organotin compounds and alkoxytitanium compounds are preferred, and organotin compounds are particularly preferred because they have a large catalytic ability in the presence of a trace amount.

  The amount of the (b3) curing catalyst is 0.005 to 5 parts by weight, preferably 0.025 to 2.5 parts by weight, based on 100 parts by weight of the component (a1). If it is less than 0.005 parts by weight, it does not act sufficiently as a curing catalyst, and not only takes a long time for curing, but also the curing in the deep part of the rubber layer far from the contact surface with air becomes insufficient. On the other hand, if it exceeds 5 parts by weight, there is no effect commensurate with the blending amount, which is meaningless and uneconomical.

  In addition to the above components, the flame retardant polyorganosiloxane composition of the present invention generally contains pigments and thixotropic agents, which are generally blended in this type of composition within a range that does not impair the effects of the present invention. Various additives such as a viscosity modifier, an ultraviolet absorber, a fungicide, a heat resistance improver, and an adhesion improver for improving the extrusion workability can be blended as necessary. These other components are appropriately blended with the component (A) or the component (B).

  In the flame-retardant polyorganosiloxane composition of the present invention, the main component component (A) and the curing agent component (B) are mixed in a weight ratio of 100: 0.6 to 100: 12. Can be obtained. A more preferable blending ratio (weight ratio) between the component (A) and the component (B) is 100: 1 to 100: 10, and a range of 100: 2 to 100: 8 is particularly preferable. The polyorganosiloxane composition of the present invention obtained by mixing the component (A) and the component (B) in the above range is cured at room temperature, has good flame retardancy, low hardness, and adhesion to various substrates. This produces a rubber-like elastic body excellent in When the mixing ratio of the component (A) and the component (B) is out of this range and the weight ratio of the component (B) is too low, the cured product becomes insufficient and a cured product cannot be obtained. Moreover, when the weight ratio of (B) component is too high, a composition hardens | cures during stirring and mixing, and a hardened | cured material with a favorable characteristic cannot be obtained. The composition of the present invention is useful as an elastic adhesive, coating material, potting material and the like for electric and electronic devices. In addition, a cured product having a viscosity (23 ° C.) of 2000 to 3000 mPa · s, good flame retardancy and curability, and a hardness of 40 or less (JIS type A) is sufficiently low. Therefore, it is particularly suitable as a potting material for sealing electronic components such as terminal portions of solar cell panels.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the scope of the present invention. In the examples, “part” means “part by weight”, and all physical properties such as viscosity are values at 23 ° C. and a relative humidity of 50%.

  Example 1

[(A) Preparation of main component]
11.0 parts of polydimethylsiloxane blocked with hydroxyl groups at both ends of the molecular chain (viscosity 3 Pa · s, amount of hydroxyl group 0.047 mmol / g), polydimethylsiloxane blocked at both ends of the molecular chain with hydroxyl groups (viscosity 0. 7Pa · s, hydroxyl group amount 0.091 mmol / g) 34.4 parts, ground silica (manufactured by Tatsumori; CRYSTALITE VX-S; average particle size 4 μm) 34.0 parts, hydrous amorphous silica (precipitated silica) ( 8. Tosoh Silica Co., Ltd .; nip seal) 1.4 parts, viscosity adjusting free oil polydimethylsiloxane (viscosity 0.1 Pa · s) 9.6 parts, zinc carbonate (Toho Zinc Co., Ltd .; zinc carbonate S) 9. 0 parts, 0.6 parts of carbon black (manufactured by Denki Kagaku Kogyo; Denka Black HS-100) and 27 ppm of chloroplatinic acid (as the amount of platinum element) are mixed, and the component (A) 100 parts of the main ingredient component was obtained.

[(B) Preparation of curing agent component]
In any case, 14.0 parts of polyethoxysiloxane as a crosslinking agent, 27.0 parts of γ-aminopropyltriethoxysilane, 27.0 parts of γ- (2-aminoethyl) aminopropyltrimethoxysilane, 1,3,5- 14.0 parts of tris {3- (trimethoxysilyl) propyl} isocyanurate, 15.0 parts of dimethylsilsesquioxane unit-containing silicone polymer, and 3.0 parts of dioctyltin dilaurate are mixed, and component (B) 100 parts of a curing agent component was obtained.

  The thus obtained (A) main component and (B) curing component were mixed at a weight ratio of 100: 3.5 to obtain a room temperature-curable polyorganosiloxane composition.

Examples 2-5, Comparative Examples 1-3
Each component shown in Table 1 was blended with the composition shown in the same table, and uniformly mixed in the same manner as in Example 1 to obtain 100 parts of the main ingredient component (A). Moreover, each component shown in Table 2 was mix | blended with the composition shown in the same table, and it mixed uniformly similarly to Example 1, and obtained 100 parts of hardening | curing agent components which are (B) components. And the obtained (A) main ingredient component and (B) hardening component were mixed in the ratio (weight ratio) shown in Table 3, and the room temperature-curable polyorganosiloxane composition was obtained.

  Next, various properties of the room temperature-curable polyorganosiloxane compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were evaluated by the methods described below. The results are shown in Table 3.

[Flame retardance]
The composition obtained by mixing the component (A) and the component (B) is poured into a mold after defoaming, and left in an atmosphere of 23 ° C. and 50% RH for 3 days to obtain a cured product having a thickness of 3 mm. It was. About this hardened | cured material, the combustion test based on UL-94V was done.

[Hardness]
The composition obtained by mixing the component (A) and the component (B) is poured into a mold (60 mm × 25 mm × 6 mm) after degassing and left in an atmosphere of 23 ° C. and 50% RH for 3 days. The hardness of the cured product was measured using a durometer type A according to JIS K 6253.

[Flowability (viscosity)]
The viscosity of the composition obtained by mixing the component (A) and the component (B) was measured using a rotational viscometer. The viscosity at the start of measurement was taken as the viscosity immediately after mixing.

[Workable time (pot life)]
The viscosity was measured using a rotational viscometer. Then, the time from the start of measurement until the viscosity reached 20 Pa · s at which the fluidity significantly decreased was measured.

[Curing property]
The viscosity change of the composition was measured using a rotational viscometer, and the time (minutes) until the scale of the viscometer (max 100,000 mPa · s) was shaken was measured. The shorter this time, the faster the cure, that is, the greater the curability.

[Deep curing]
The composition obtained by mixing the component (A) and the component (B) was poured into a polystyrene cup and allowed to cure in an atmosphere of 23 ° C. and 50% RH for 3 days. About the obtained hardened | cured material, the cup was broken and the upper layer and the lower layer were cut out to the thickness of 6 mm, respectively, and the hardness of each layer was measured using durometer type A based on JISK6253. And if the difference in hardness between the upper layer and the lower layer was 10 or more, x was evaluated as 5 and 10 was evaluated as Δ, and if it was less than 5, it was evaluated as ○.

[Adhesiveness]
The composition was applied to various substrates shown in Table 3 (length 25 mm × width 10 mm × thickness 1 mm), and allowed to stand in an atmosphere of 23 ° C. and 55% RH for 3 days to prepare a test specimen. And the hardened layer of these test bodies was peeled off with a fingertip or a spatula etc., and the cohesive failure rate was measured by 10% unit by visual observation. And the adhesiveness was determined according to the following criteria.
○ ... Cohesive failure rate 100%
△ ... Cohesive failure rate 50-90%
X ... Cohesive failure rate 0-40%

  In the base materials shown in Table 3, as the modified polyphenylene oxide (modified PPO), noryl (trade name of SABIC Innovative Plastics) is used, and as the poly (paraphenylene benzobisoxazole), zylon (trade name of Asahi Kasei Corporation). Nylon (trade name of DuPont) was used as the polyamide, and the adhesion to these substrates was examined.

  As is apparent from Table 3, the polyorganosiloxane compositions obtained in Examples 1 to 4 are excellent in curability, flame retardancy and adhesiveness. In particular, the polyorganosiloxane composition obtained in Example 1 The object is suitable as a potting material for sealing an electronic component such as a terminal portion in a terminal box of a solar cell panel.

  That is, the polyorganosiloxane composition obtained in Example 1 has a viscosity of 4000 mPa · s or less, has good fluidity suitable for filling in a narrow gap, and has a curable measurement result of 10 minutes. The film is formed on the surface in 5 to 10 minutes and loses fluidity, but it has a working life of 5 minutes or more and is sufficient to avoid curing inside the machine (such as a stirrer). Ejectability is ensured. Moreover, since the judgment result of the combustion test based on UL-94V is V-1 or higher, and it has good flame retardancy, the hardness of the cured product is 40 or less. Is sufficiently relaxed, and the terminal portion is not damaged by the stress.

  On the other hand, in Comparative Example 1, the mixing ratio of the component (A) and the component (B) is out of the predetermined range (100: 0.6 to 100: 12), and the weight ratio of the component (B) is high. Therefore, the composition began to thicken and harden during the stirring and defoaming of the component (A) and the component (B), and a cured product that could be used for measurement and evaluation could not be obtained. In Comparative Example 2, since the weight ratio of the component (B) was too low, the cured product itself could not be obtained. Moreover, since the polyorganosiloxane composition obtained in Comparative Example 3 did not contain zinc carbonate which is a flame retardant imparting filler, the flame retardancy was not sufficient and the adhesiveness was inferior.

Claims (3)

(A1) a polyorganosiloxane having a viscosity of 0.02 to 100 Pa · s at 23 ° C. in which both ends of the molecular chain are blocked with hydroxyl groups;
(A2) a flame retardant filler,
(A3) a silica-based filler;
(A4) main ingredient component (A) each containing a platinum compound which is a flame retardant imparting agent;
(B1) General formula (1):
R ¹ _a Si (OR ² ) _4-a (1)
Wherein R ¹ and R ² are unsubstituted monovalent hydrocarbon groups which may be the same or different, and a is an integer of 0, 1 or 2. And / or its hydrolysis condensate,
(B2) an amino group-substituted alkoxysilane;
(B3) a curing agent component (B) containing a curing catalyst, and the mixing ratio of the main agent component (A) and the curing agent component (B) is 100: 0.6 to 100: 12. A flame retardant polyorganosiloxane composition for sealing electronic parts, wherein the composition is 12.   The flame retardant polyorganosiloxane composition for sealing electronic parts according to claim 1, wherein the (a2) flame retardant imparting filler contains zinc carbonate.   The flame retardant polyorganosiloxane composition for sealing electronic parts according to claim 1 or 2, wherein the (a3) silica-based filler contains hydrous amorphous silica (precipitated silica).