WO2003018692A1

WO2003018692A1 - Flame retardant organic resin composition

Info

Publication number: WO2003018692A1
Application number: PCT/JP2002/008698
Authority: WO
Inventors: Koji Nakanishi; Hidekatsu Hatanaka; Haruhiko Furukawa; Koji Shiromoto; Hiroshi Ueki; Yoshitsugu Morita
Original assignee: Dow Corning Toray Silicone Co.,Ltd.
Priority date: 2001-08-28
Filing date: 2002-08-28
Publication date: 2003-03-06

Abstract

A flame retardant organic resin composition comprising an organic resin with an aromatic ring, a branched organopolysiloxane, and an organopolysiloxane selected from a diorganopolysiloxane and an organopolysiloxane containing an epoxy group is disclosed.

Description

DESCRIPTION

Flame Retardant Organic Resin Composition

[0001] The present invention relates to a flame retardant organic resin composition comprising an organic resin with an aromatic ring, a branched organopolysiloxane, and an organopolysiloxane selected from a diorganopolysiloxane and an organopolysiloxane containing an epoxy group. [0002] Organic resins with an aromatic ring, such as an aromatic polycarbonate, are characterized by high mechanical strengths in combination with excellent electrical characteristics. Therefore, these resins find wide application in the manufacture of parts for office automation machines, automobiles, construction, and road building equipment. It has been known heretofore to impart flame retardant properties to organic resins that contain aromatic rings by mixing these resins with compounds containing chlorine or bromine atoms. Problems associated with the use of the organic resin compositions prepared from aforementioned mixtures results in compositions that produce a large amount of black smoke during burning harmful to human health or generate a gas that causes corrosion of metals. [0003] Many suggestions have been made for providing a flame retardant polycarbonate resin composition that does not generate a harmful gas during burning. For example, Japanese Unexamined Patent Application Publication (hereinafter referred to as "Kokai") H8- 176425 discloses an aromatic polycarbonate resin composition comprising an epoxy-containing silicone resin (a polyglycidoxypropyl-silsesquioxane obtained by hydrolyzing γ-glycidoxypropyltrimethoxysilane) mixed with an organic alkali-metal salt. However, since the epoxy-containing polyorganosiloxane composition disclosed in Kokai H8- 176425 contains a large amount of epoxy groups, it impairs compounding stability of the aromatic polycarbonate resin composition and decreases its moldability. Kokai H10-139964 discloses a polycarbonate composition obtained by combining an aromatic polycarbonate resin with a high-molecular- weight silicone resin that comprising bi-functional siloxane units (D units) and tri-functional siloxane units (T-units) and has a weight-average molecular weight exceeding 10,000. Nevertheless, the Kokai HlO-139964 composition also possesses poor moldability and has insufficient flame retardant properties. In addition, it cannot be easily produced. [0004] Kokai HI 1-140294 describes a flame retardant polycarbonate resin composition prepared by combining an aromatic polycarbonate with a silicone resin having more than 80 mole % of phenyl groups, whereas Kokai HI 1-222559 discloses a flame retardant polycarbonate resin composition prepared by combining silicone resins with phenyl and alkoxy groups. However, the above compositions have insufficient flame retardant properties, and also are unsatisfactory in use. Furthermore, Kokai HI 1-140329 describes a flame retardant polycarbonate resin composition prepared from a silica powder admixed with an aromatic polycarbonate resin and a silicone resin that contains phenyl groups and alkoxy groups. The Kokai HI 1-140329 compositions are disadvantageous in requiring the use of a silica powder and therefore is difficult in production.

[0005] The present inventors have found that flame retardant properties of organic resins with aromatic rings, such as aromatic polycarbonate resins, can be improved by combining them with certain organopolysiloxanes and a branched organopolysiloxane. [0006] The present invention provides a flame retardant organic resin composition comprising:

(A) 100 parts by weight of an organic resin that contains an aromatic ring;

(B) 0.01 to 20 parts by weight of a branched organopolysiloxane represented by the average molecular formula

(R¹3SiO₁/₂)_a(R² ₂SiO₂/₂)_b(R³SiO_3/2)_c(SiO₄/₂)_d(R⁴O_1/2)e(HO_1/2)_f where R¹, R², R³ are independently monovalent hydrocarbon groups selected from an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, and an aryl group having 6 to 12 carbon atoms, and R⁴ is an alkyl group, the content of aryl groups in R being within the limits of 20 to 100 mole%, a, b, d, e,f are 0 or positive numbers, and c is a positive number greater than zero; and

(C) 0.01 to 5 parts by weight of an organopolysiloxane selected from a diorganopolysiloxane and an organopolysiloxane containing an epoxy group.

[0007] Component (A) is an organic resin that contains an aromatic ring. The following are non-limiting examples of such resins: thermoplastic resins such as an aromatic polycarbonate resin or its alloy; a polyphenylene ether resin or its alloy; a polysulfone resin; a polyarylate resin, polyethyleneterephthalate resin, polybutyleneterephthalate resin, or a similar aromatic polyester resin; an aromatic polyamide resin; a polyimide resin; a polyphenylenesulfide resin; a polystyrene resin, high-impact-resistant polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene (AS) resin, or a similar styrene-type resin; or thermosetting resins such as a novolac-type epoxy resin. Typically, the organic resin is a aromatic polycarbonate resin and related alloys.

[0008] Component (B) is a branched organopolysiloxane represented by the following average molecular formula:

(R¹ ₃SiO_1/2)_a(R² ₂ SiO_2/2)_b(R³SiO_3/2)_c(SiO_4/2)_d(R⁴O_1/2)_e(HO_1/2)_f where R¹, R², R³ are monovalent hydrocarbon groups selected from an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, and an aryl group having 6 to 12 carbon atoms, and R⁴ is an alkyl group, the content of aryl groups in R³ being within the limits of 20 to 100 mole%, a, b, d, e,f are 0 or positive numbers, and c is a positive number greater than 0. Component (B) may contain in one molecule tri-functional siloxane units (T- units) represented by the following formula: R SιO_3/2, and, if necessary, monofunctional siloxane units (M-units) of formula R¹ ₃SiO_1/2 and bifunctional siloxane units (D-units) of formula R ₂SiO_2/2. If necessary, in addition to the aforementioned groups and within the limits not conflicting with the purposes of the present invention, component (B) may contain quatrofunctional units (Q-units) of formula SiO_4/2.

[0009] Component (B) may also preferably comprise a branched organopolysiloxane represented by the following average molecular formula: (R² ₂ SiO_2/2)_b(R³SiO_3/2)_c(SiO₄/₂)_d(R⁴O_1/2)_e(HO_1/2)_f (where R², R³, R⁴, b, c, d, e, and f are the same as defined above), a branched organopolysiloxane represented by the following average molecular formula :

(R² ₂ SiO_2/2)_b(R³SiO_3/2)_c(HO_1/2)_f (where R , R , b, c, and f are the same as defined above), or a branched organopolysiloxane represented by the following average molecular formula: (R³SiO_3/2)_c(HO_1/2)_f (where R , c, and f are the same as defined above).

[0010] In the above formula, R¹, R², R³ can be exemplified by methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, or similar alkyl groups; vinyl group, butenyl group, pentenyl group, hexenyl group, or similar alkenyl groups; phenyl group, tolyl group, xylyl group, naphthyl group, or similar aryl groups. Among the above, R³ should contain aryl groups in an amount from 20 to 100 mole %, alternatively from 50 to 100 mole%, or alternatively from 70 to 100 mole %. It is recommended that aryl groups of R³ comprise phenyl groups. In the case when R³ comprises a phenyl group, their content should be within the range of 70 mole % to 100 mole %. There are no special restrictions with regard to the amount of phenyl groups in all substituents. However, typically this amount is within the range of 20 to 100 mole %, or alternatively 50 to 100 mole %. When it is required that the composition possess transparency, the amount of phenyl groups in R³ should be no less than 90 mole %.

[0011] Component (B) may contain silicon-bonded hydroxyl groups. Such groups may be contained in an amount of 0 to 8 wt.%, preferably in an amount of 1 to 7 wt.%. Component (B) may also contain silicon-bonded methoxy, et oxy, n-propoxy, isopropoxy, butoxy, or similar alkoxy groups with 1 to 12 carbon atoms. It is recommended for component (B) to have a weight-average molecular weight between 300 and 10,000. If the weight-average molecular weight of component (B) exceeds 10,000, the composition of the present invention will have poor moldability, pose problems during synthesis. Normally, the weight-average molecular weight is determined by gel permeation chromatography (GPC). [0012] Preferably, typical examples of component (B) are branched organopolysiloxane represented by the following average molecular formula :

((CH₃)₂ SiO_2/2)_b(C₆H₅SiO_3/2)_c(HO_1/2)_f (where b, c, and f are the same as defined above), and a branched organopolysiloxane represented by the following average molecular formula: (R³SiO_3/2)_c(HO_1/2)_f (where R³ are propyl and phenyl group and c and fare the same as defined above).

[0013] Component (B) can be used in an amount of 0.01 to 20 parts by weight, alternatively 0.1 to 20 parts by weight, or alternatively 0.1 to lO parts by weight for each 100 parts by weight of component (A).

[0014] Component (C) is an organopolysiloxane selected from a diorganopolysiloxane and an organopolysiloxane that contains an epoxy group.

[0015] The diorganopolysiloxane can be preferably represented by the following average molecular formula: R⁵ ₃-SiO(R⁶ ₂SiO)_n-SiR⁵ ₃

where R⁵ is a substituted group selected from a monovalent hydrocarbon group, an alkoxy group, and a hydroxyl group; R⁶ is a monovalent hydrocarbon group; n is a number which results in a viscosity which at 25°C is within the range of 10 to 1,000,000 mPa-s. In the above formula, the monovalent hydrocarbon group of R5 can be exemplified by methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, or similar alkyl groups; vinyl group, allyl group, butenyl group, pentenyl group, hexenyl or similar alkenyl groups; phenyl group, tolyl group, xylyl group, naphthyl group or similar aryl groups; benzyl group, phenethyl group, or similar aralkyl groups. The alkoxy groups can be represented by methoxy group, ethoxy group, n-propyl group, isopropyl group, and butoxy group. The monovalent hydrocarbon of R may be exemplified by methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, or similar alkyl groups; vinyl group, allyl group, butenyl group, pentenyl group, hexenyl or similar alkenyl groups; phenyl group, tolyl group, xylyl group, naphthyl group or similar aryl groups; benzyl group, phenethyl group, or similar aralkyl groups. Typically, methyl groups constitute 50 mole % or more, alternatively 70 mole % or more, or alternatively 90 mole % or more of R⁶. The number n is such to provide the diorganopolysiloxanes with a viscosity within the range of 10 to 1,000,000 mPa-s, alternatively between 20 and 100,000 mPa-s at 25°C. [0016] An appropriate diorganopolysiloxane may be represented by a dimethylpolysiloxane having both molecular terminals capped with trimethylsiloxy groups, a dimethylpolysiloxane having one molecular terminal capped with a trimethylsiloxy group and the other molecular terminal capped with a hydroxyl group, a dimethylpolysiloxane having one molecular terminal capped with a trimethylsiloxy group and the other molecular terminal capped with a methoxy group, a dimethylpolysiloxane having one molecular terminal capped with a trimethylsiloxy group and the other molecular terminal capped with a dimethylvinylsiloxy group, a dimethylpolysiloxane having both molecular terminals capped with hydroxyl groups, a dimethylpolysiloxane having both molecular terminals capped with methoxy groups, a dimethyl polysiloxane having both molecular terminals capped with dimethylvinylsiloxy groups, or a similar dimethylpolysiloxane; a copolymer of a methylphenylsiloxane and a dimethylsiloxane having both molecular terminals capped with trimethylsiloxy groups, a copolymer of a methylphenylsiloxane and a dimethylsiloxane having one molecular terminals capped with a trimethylsiloxy group and the other molecular terminal capped with a hydroxyl group, a copolymer of a methylphenylsiloxane and a dimethylsiloxane having one molecular terminals capped with a trimethylsiloxy group and the other molecular terminal capped with a methoxy group, a copolymer of a methylphenylsiloxane and a dimethylsiloxane having both molecular terminals capped with hydroxyl groups, a copolymer of a methylphenylsiloxane and a dimethylsiloxane having both molecular terminals capped with methoxy groups, or a similar dimethylsiloxane- methylphenylsiloxane copolymer; a copolymer of a dilphenylsiloxane and a dimethylsiloxane having both molecular terminals capped with trimethylsiloxy groups, a copolymer of a diphenylsiloxane and a dimethylsiloxane having one molecular terminals capped with a trimethylsiloxy group and the other molecular terminal capped with a hydroxyl group, a copolymer of a diphenylsiloxane and a dimethylsiloxane having one molecular terminals capped with a trimethylsiloxy group and the other molecular terminal capped with a methoxy group, or a similar dimethylsiloxane-diphenylsiloxane copolymers. Typically among the above are dimethylpolysiloxanes. [0017] As discussed supra, the silicon-bonded organic groups contained in the diorganopolysiloxane of component (C) are typically unsubstituted monovalent hydrocarbon groups. Also within the limits of the present invention, the aforementioned monovalent hydrocarbon groups can be used in combination with a small amount of hydroxyl groups, alkoxy groups, or substituted monovalent hydrocarbons such as γ-aminopropyl group, γ- methacryloxypropyl group, or a similar acryl-substituted alkyl group; a γ- polyoxyethylenepropyl group, or a similar polyoxyethylene-substituted alkyl group, ester- substituted alkyl group, etc..

[0018] When a diorganopolysiloxane is used as component (C), it is typically used in an amount of 0.01 to 5 parts by weight, alternatively 0.05 to 2 parts by weight, or alternatively, 0.1 to 1 parts by weight for each 100 parts by weight of component (A). If the diorganopolysiloxane is used in an amount smaller than 0.01 parts by weight, it would be impossible to impart to the obtained thermoplastic resin composition the desired flame retardant properties. If, on the other hand, the diorganopolysiloxanes is used in an amount exceeding 5 parts by weight, the products molded from the composition of the present invention will have a reduced mechanical strength. It is not yet exactly known why the combined use of components (C) and (B) improves moldability and flame retardant properties of the composition. Although not to be limited by any theory, the present inventors speculate the diorganopolysiloxane works as an affinity improvement agent for components (A) and (B), so that (B) is distributed in (A) more uniformly. [0019] Component (C) can also be an organopolysiloxane containing an epoxy group.

Typically, the aforementioned epoxy group is connected to a silicon atom of the organopolysiloxane through a divalent hydrocarbon group. The following are non-limiting examples of epoxy-group-containing organic groups: 2,3-epoxypropyl group, 3,4-epoxybutyl group, 4,5-epoxypentyl group, 2-glycidoxyethyl group, 3-glycidoxypropyl group, 4- glycidoxybutyl group, 2-(3,4-epoxycyclohexyl) ethyl group, and 3-(3,4-epoxycyclohexyl) propyl group. The organopolysiloxane containing an epoxy group can also contain other organic groups such as the following non-limiting examples: methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, or a similar alkyl group; vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, or a similar alkenyl group; phenyl group, tolyl group, xylyl group, naphthyl group, or a similar aryl group; benzyl group, phenethyl group, or a similar aralkyl group; chloromethyl group, 3-chloropropyl group, 3,3,3- trifluoropropyl group, nonafluorobutylethyl group, or a similar halogen-substituted alkyl group. The organopolysiloxane of component (C) may have a linear, branched, net-like, or ring-like molecular structure, but typically is a linear molecular structure. Typically, component (C) has a weight-average molecular weight between 100 and 100,000, alternatively between 300 and 20,000. [0020] Typical examples of organopolysiloxanes containing an epoxy group suitable for component (C) are compounds represented by the following general formulae (1) and (2), where /, m, and n are positive numbers:

General formula (1):

General formula (2):

[0021] Typically, the amount of epoxy groups contained in the organopolysiloxane of component (C) can be within the range of 0.01 to 60 mole %, alternatively between 0.1 and 15 mole % with respect to the amount of all silicon-bonded organic groups. If the amount of epoxy groups exceeds 60 mole %, the obtained organic resin composition would have low flowability and reduced moldability. When the organopolysiloxane containing an epoxy group is used as component (C), it can be used in an amount of 0.01 to 4 parts by weight for each 100 parts by weight of component (A). [0022] The composition of the invention is prepared from components (A) through (C).

In order to further improve flame retardant properties, the composition may also be combined with component (D) in the form of an alkali-metal salt of an organic acid or an organic acid ester. An organic acid suitable for component (D) may comprise an organic sulfonic acid, or an organic carboxylic acid. An example of an organic acid ester is an organic phosphoric acid ester. An alkali metal may comprise sodium, potassium, lithium, and cesium. Examples of alkali-earth metals are magnesium, calcium, strontium, and barium. Typically, component (D) is selected from the above metal salts of an organic sulfonic acid, as well as metal salts of a perfluoroalkanesulfonic acid and aromatic sulfonesulfonic acid. The following are illustrative examples of metals salts of a perfluoroalkanesulfonic acid: a sodium perfluorobutanesulfonate, potassium perfluorobutanesulfonate, sodium perfluoromethylbutanesulfonate, potassium perfluoromethylbutanesulfonate, sodium perfluorooctanesulfonate, potassium perfluorooctanesulfonate, etc. The following are specific examples of metals salts of an aromatic sulfonesulfonic acid: a sodium salt of a diphenylsulfone-3-sulfonic acid, a potassium salt of a diphenylsulfone-3-sulfonic acid, a sodium salt of 4,4-dibromodiphenylsulfone-3- sulfonic acid, a potassium salt of 4,4-dibromodiphenylsulfone-3 -sulfonic acid, a disodium salt of diphenylsulfone-3,3-disulfonic acid, a dipotassium salt of diphenylsulfone-3,3-disulfonic acid, etc. When present, component (D) can be used in an amount of 0.01 to 1 wt.% for each 100 parts by weight of component (A). [0023] The composition of the present invention can further comprise component (E), typically a fluororesin, for improving the flame retardant properties of the composition. Typically, the fluororesin is in a powdered form such as a fluorinated ethylene resin (a monomer having a hydrogen atom of the ethylene substituted by a fluorine atom, e.g., a tetrafluoro ethylene resin powder), trifluoroethylene resin, tetrafluoroethylene hexaethylenepropylene resin, fluorovinyl resin, fluorovinylidene resin, and a difluorinated ethylene dichloride resin. Normally, particles of the aforementioned fluororesin powder have a spherical shape, but may also have a fibrous shape. It can be added in an amount of 0.01 to 5 parts by weight for each 100 parts by weight of component (A). [0024] The composition of the invention can be further combined with conventional additives normally added to (A) organic resin containing an aromatic ring. These additives can be: glass fibers, glass beads, glass flakes, carbon black, calcium sulfate, calcium carbonate, calcium silicate, titanium oxide, alumina, silica, asbestos, talc, mica, quartz, or a similar inorganic filler; various synthetic resins, elastomers, or similar organic resin additives; hindered-phenol-type oxidation inhibitors, zinc phosphoric acid ester-type oxidation inhibitors, phosphoric acid ester-type oxidation inhibitors, amine-type oxidation inhibitors, or similar oxidation inhibitors; aliphatic carboxylic acid esters; paraffin, polyethylene wax, or a similar lubricant; organic or inorganic pigments or coloring agents; benzotriazol-type ultraviolet ray absorbers, benzophenone-type ultraviolet ray absorbers, or similar ultraviolet ray absorbers; hindered-amine-type light stabilizers; phosphorous-type flame retarders, or similar flame retarders; various mold-release agents; and various antistatics.

[0025] The composition of the invention is easily prepared by uniformly mixing components (A) through (C), or (A) through (D), or (A) through (E). Mixing can be carried out with the use of a ribbon blender, Henschel mixer, B anbury mixer, drum tumbler, single- screw extruder, twin-screw extruder, kneader, multiple-axle screw extruder, etc. Mixing can be carried out with heating to a temperature of 200 to 350°C.

[0026] The above-described composition of the invention possesses excellent moldability and flame retardant properties. Due to its properties, the composition of the invention is suitable as a material for manufacturing parts for domestic electrical appliances, housing for automobile interiors, electric and electronic devices, etc. [0027] The invention will be further described in detail with reference to the ensuing practical and reference examples. In these examples, flame retardant properties of the aromatic polycarbonate resin compositions were measured in accordance with JIS-K7201 "Non-Flammability Test of Plastics Based on Oxygen Index".

[0028] Another criterion for evaluation of flame retardant properties which was used in the examples was a flame-resistance criterion specified by UL94 Test (Underwriter Laboratory Test for Flammability of Plastic Materials for Parts In Devices and Appliances). The UL-94 Test consists of evaluating flame retardant properties in terms of flame duration and drips of flaming particles after 10 sec. burner flame application to a vertically held specimen of a predetermined size. The ratings were classified as follows:

[0029] The aforementioned flame duration was measured as duration of flame after removal of the burning source from the specimen, while flame dripping was evaluated by observing whether specimen drips flaming particles to ignite the cotton located at a distance of about 300 mm from the lower end of the specimen. The specimen used in this test had a thickness of 3 mm.

[0030] Moldability of the aromatic polycarbonate resin composition was evaluated in terms of a melt index (MI value) measured in compliance with JIS-K7210. Measurements were carried out with the use of a 2 kg load and under a temperature of 300°C.

[0031] Epoxy-group-containing organopolysiloxanes (SNR1 and SNR2) used in

Reference Example 1 and Reference Example 2 and branched organopolysiloxanes (SNR3, SNR4, SNR5, and SNR6) used in Reference Examples 3 to 6 were expressed by average molecular formulae shown in Table 1 and had characteristics shown in Table 2. In Table 1, R designates γ-glycidoxypropyl group, Me designates methyl group, Pr designates propyl group, and Ph designates phenyl group. Chemical structure analysis of the branched organopolysiloxanes used in the practical examples was carried out with the use of nuclear magnetic resonance (NMR) spectra. A weight-average molecular weight was measured with the use of gel permeation chromatography (GPC). The obtained values of the weight-average molecular weight were recalculated to molecular weight of a known polystyrene used as a reference.

Reference Example 1

Preparation of an Organopolysiloxane Containing an Epoxy Group (SNR1)

[0032] A 1 liter 4-neck flask equipped with a stirrer, cooler, dripping funnel, and thermometer was filled with 300 g of a dimethylpolysiloxane having on both molecular terminals silicon-bonded hydrogen atoms (60 dimethylsiloxane units), 150 g of toluene, and 16 g of an allylglycidyl ether. An isopropanol solution of a chloroplatinic acid was then added by dripping in a catalytic quantity. A saturated aqueous solution of sodium bicarbonate was added in an amount sufficient for neutralization of the acid. The mixture was then stirred with heating, and a reaction was carried out. Upon completion of the reaction, the solvent was removed by distillation, a non-dissolved residue was removed by filtering, and an epoxy- containing organopolysiloxane as component (C) was produced. The obtained epoxy- containing organopolysiloxane (hereinafter referred to as SNR1) was analyzed. The result of the analysis showed a substance with an average structural formula given below. The weight- average molecular weight of the product was 4600, and an epoxy equivalent was 2300.

Reference Example 2

Preparation of an Organopolysiloxane Containing an Epoxy Group (SNR2)

[0033] A 1 liter 4-neck flask equipped with a stirrer, cooler, dripping funnel, and thermometer was filled with 200 g of a copolymer of a methylhydrogensiloxane and a dimethylsiloxane having both molecular terminals capped with trimethylsiloxy groups (120 dimethylsiloxane units and 174 methylhydrogensiloxane units), 100 g of toluene, and 205 g of allylglycidyl ether. An isopropanol solution of chloroplatinic acid was then added by dripping in a catalytic quantity. A saturated aqueous solution of sodium bicarbonate was added in an amount sufficient for neutralization of the acid. The mixture was then stirred with heating, and a reaction was carried out. Upon completion of the reaction, the solvent was removed by distillation, a non-dissolved residue was removed by filtering, and an epoxy- containing organopolysiloxane as component (C) was produced. The obtained epoxy- containing organopolysiloxane (hereinafter referred to as SNR2) was analyzed. The result of the analysis showed a substance with an average structural formula given below. The weight- average molecular weight of the product was 39000, and an epoxy equivalent was 230.

Reference Example 3

Preparation of a Branched Organopolysiloxane (SNR3) [0034] A 2 liter 4-neck flask equipped with a stirrer, cooler, dripping funnel, and thermometer was filled by dripping with a mixed solution containing 180 g of toluene, 60g of isopropyl alcohol, 250 g of water, 147 g of phenyltrichlorosilane cooled on an ice bath, and 52.8 g of isopropyltrichlorosilane. Upon completion of dripping, the mixture was stirred for 30 min. at room temperature and then for 3 hours was subjected to refluxing for completion of hydrolysis. The product was kept in a static state, and an aqueous layer was removed. Water was then again added, the product was stirred, retained intact, and a water layer was again removed, and this procedure was repeated until complete neutralization of a washing solution. An aqueous component was further removed from the obtained toluene solution by azeotropic dehydration. After cooling, a non-dissolved residue was removed by filtering, and toluene was removed by distillation in vacuum. As a result, 115.2 g of a solid branched organopolysiloxane as component (B) were obtained. The obtained branched organopolysiloxane (hereinafter referred to as SNR3) contained 70 mole % of PhSiO _/2 units and 30 mole % of C₃H₇SiO_3/2 units. Content of hydroxyl groups was 6.0 wt.%, and the weight- average molecular weight was equal to 1,600.

Reference Example 4

Preparation of a Branched Organopolysiloxane (SNR4)

[0035] A 1 liter 4-neck flask equipped with a stirrer, cooler, dripping funnel, and thermometer was filled with 110 g of toluene, 40g of methylethylketone, and 40 g of water. While the flask was cooled on an ice bath, a mixed solution containing 114.8 g of phenyltrichlorosilane, 17.5 g of dimethyldichlorosilane, and 40 g of toluene were added via a dripping funnel. Upon completion of dripping, the mixture was stirred for 30 min. at room temperature, and then for lhour was subjected to refluxing for completion of hydrolysis. After cooling, 30 ml of toluene were added, the solution was kept intact, and an aqueous layer was removed. For washing the product, addition of water, stirring, retention in a static state, and removal of the aqueous layer were repeated three times. A 4% aqueous solution of sodium bicarbonate was added to the toluene phase, and washing was carried out three times after 1 hour refluxing and cooling. As a result, a toluene solution of a branched organopolysiloxane was produced. A solid part of the obtained branched organopolysiloxane was adjusted to 30 wt. % and combined with 0.8 g of a 10% aqueous solution of potassium hydroxide. An ester adapter was then attached , and refluxing was carried out with separation of the generated water. Cooling was started 4 hours after initiation of refluxing. After neutralization with an acetic acid, the product was three times washed with water and dried. As a result, a solid organopolysiloxane as component (B) was obtained. The obtained branched organopolysiloxane (hereinafter referred to as SNR4) contained 80 mole % of PhSiO _/2 units and 20 mole % of Me₂SiO_2/ units. Content of hydroxyl groups on the molecular terminals was 3.4 wt.%, and the weight-average molecular weight was equal to 4000.

Reference Example 5 Preparation of a Branched Organopolysiloxane (SNR5)

[0036] A 1 liter 4-neck flask equipped with a stirrer, cooler, dripping funnel, and thermometer was filled with 90 g of toluene and 430 g of water. After heating to 80°C, a mixed solution consisting of 169 g of phenyltrichlorosilane and 26 g of dimethyldichlorosilane was added via a dripping funnel. The product was subjected to lhour refluxing for completion of hydrolysis. After cooling, the solution was kept intact, and an aqueous layer was removed. For washing the product, addition of water, stirring, retention in a static state, and removal of the aqueous layer were repeated three times. The obtained organopolysiloxane solution was filtered, the non-solved residue was removed, and the product was dried. As a result, a solid organopolysiloxane as component (B) was obtained. The obtained branched organopolysiloxane (hereinafter referred to as SNR5) contained 80 mole % of PhSiO_3/2 units and 20 mole % of Me SiO_2/ units. Content of hydroxyl groups on the molecular terminals was 1.7 wt.%, and the weight-average molecular weight was equal to

20,000.

Reference Example 6

Preparation of an Organopolysiloxane Containing an Epoxy Group (SNR6)

[0037] A 500 mL 4-neck flask equipped with a stirrer, cooler, dripping funnel, and thermometer was filled with 50 g of 3-glycidoxypropyl trimethoxysilane and lOOg of methanol. Following this, 23 g of 0. IN hydrochloric acid were added via the dripping funnel with constant stirring. The product was stirred for 30 min. at room temperature an then for 2 hours with heating to 70°C. After distillation in vacuum, 35 g of a colorless transparent glycidoxypropylpolysilsesquioxane as component (C) (a viscous liquid) (hereafter, SNR6) was obtained. The obtained substance had a viscosity of 1500 mPa-s and the weight-average molecular weight was equal to 600. Table 1

Table 2

Practical Examples 1 to 7 [0038] Flame retardant polycarbonate resin compositions were prepare by mixing the components given below in proportions shown in Tables 3 and 4: component (A) in the form of an organic resin with an aromatic ring (Toughlon A1900 of Idemitsu Petrochemical Co., Ltd.); component (C) in the form of epoxy-containing organopolysiloxanes SNR1 and SNR2 shown in Tables 1 and 2; component (B) in the form of branched organopolysiloxanes SNR3 and SNR4 to shown in Tables 1 and 2; component (D) in the form of sodium trichlorobenzenesulfonate; and component (E) in the form of a perfluoroethylene powder (Polyfuron MPA, FA-500 of Daikin Industries Co., Ltd.). The compositions were prepared as follows: an aromatic polycarbonate resin was loaded into a mixer ("Laboplastomill", Toyo Seiki Co., Ltd.) and melted by heating to 280-320°C. Branched organopolysiloxanes were loaded, mixed, and kneaded. In Practical Example 5, a fluororesin powder was added and kneaded. In Practical Examples 6 and 7, sodium trichlorobenzensulfonate was also added and kneaded. The obtained flame retardant polycarbonate resin compositions were tested with regard to their moldability (in terms of their melt index MI). [0039] The obtained compositions were then used for injection molding at 280 to 320°C. The molded articles were measured with regard to their oxygen index and transparency. The results of these measurements are given in Tables 3 and 4 below. Comparative Examples 1 to 8

[0040] Polycarbonate resin compositions were prepared by the same method as in

Practical Example 1, with the exception that the epoxy-containing organopolysiloxanes of Practical Example 1 and the branched organopolysiloxanes were not used in combination. [0041] The obtained compositions were then used for injection molding at 280 to

320°C. The molded articles were measured with regard to their oxygen index. The results of these measurements are given in Table 5.

Table 3

Table 4

Table 5

Practical Examples 8 through 15 and Comparative Examples 9 through 15

[0042] The compositions of these examples were prepared by using component (A) in the form of an aromatic polycarbonate resin (the product of Idemitsu Petrochemical Co., Ltd., trademark "Tafuron A1900") or a polycarbonate- ABS (acrylonitrile-butadiene-styrene copolymer) resin alloy (the product of Teijin Chemical Ltd., trademark "Multilon T3011"). Component (B) comprised branched organopolysiloxanes SNR3, SNR4, and SNR5 of Reference Examples 3 through 5. Component (C) was represented by a polydimethylsiloxane (hereinafter referred to as SNR7) having both molecular terminals capped with trimethylsiloxy groups and having a 25°C viscosity of 12500 mPa-s or a dimethylpolysiloxane (hereinafter referred to as SNR8) having both molecular terminals capped with trimethylsiloxy groups and having a 25°C viscosity of 100 mPa-s. Component (D) was represented by a sodium perfluorobutane sulfonate (the product of Dainippon Ink and Chemicals, Co., Ltd. trademark "Megafac FI 14". Component (E) was represented by a fluororesin powder (a perfluoroethylene resin produced by Daikin Industries Co., Ltd. under trademark Polyfureon MPA, FA-500. Flame retardant polycarbonate resin compositions were prepared by mixing the aforementioned components in proportions shown in Tables 3 and 4 given below. The compositions were prepared as follows: the polycarbonate resin or a polycarbonate -ABS resin alloy was loaded into a mixer ("Laboplastomill", Toyo Seiki Seisakusho Co., Ltd.), where it was heated and fused at 280 to 320°C. The mixer was loaded with the branched organopolysiloxane and/or dimethylpolysiloxane. The components were then kneaded. In Practical Examples 12 through 14, the kneaded composition further contained a sodium perfluorobutane sulfonate and/or fluororesin. As a result, flame retardant polycarbonate resin compositions were prepared. The obtained compositions were tested with regard to their moldability (MI index). The compositions were subjected to injection molding at 280 to 320°C, and the molded articles were tested with regard to their flame retardant properties. The results of the tests are shown in Tables 6, 7, 8, and 9.

Table 6

Table 7

Table 8

Table 9

Claims

1. A flame retardant organic resin composition comprising:

(A) 100 parts by weight of an organic resin that contains an aromatic ring; (B) 0.01 to 20 parts by weight of a branched organopolysiloxane represented by the average molecular formula,

(R¹ ₃SiO_1/2)_a(R² ₂SiO_2/2)_b(R³SiO_3/2)_c(SiO_4/2)_d(R⁴O_1/2)e(HO_1/2)_f where R¹, R², R³ are independently monovalent hydrocarbon groups selected from an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, and an aryl group having 6 to 12 carbon atoms, and R⁴ is an alkyl group, the content of aryl groups in R³ being within the limits of 20 to 100 mole%, a, b, d, e, f are 0 or positive numbers, and c is a positive number greater than zero; and

2. The flame retardant organic resin composition of Claim 1, wherein component (A) is an aromatic polycarbonate or an alloy thereof.

3. The flame retardant organic resin composition of Claim 1, wherein component (B) is a branched organopolysiloxane represented by the average molecular formula, (R²2SiO₂/₂)_b(R³SiO_3/2)_c(SiO₄/₂)_d(R⁴O₁/₂)e(HO₁/₂)f where R², R³, R⁴, b, c, d, e, and/are the same as defined in claim 1.

4. The flame retardant organic resin composition of Claim 1, wherein component (B) is a branched organopolysiloxane represented by the average molecular formula, (R² ₂SiO₂/2)_b(R³SiO_3/2)_c(HO_1/2)_f where R², R³, b, c, and/are the same as defined in claim 1.

5. The flame retardant organic resin composition of Claim 1, wherein component (B) is a branched organopolysiloxane represented by the average molecular formula, (R³SiO /₂)_c(HOι/₂)_f where R³, c, and/are the same as defined in claim 1.

6. The flame retardant organic resin composition according to any one of Claims 1 - 5, wherein the content of silicon-bonded hydroxyl groups of component (B) is within the range of 0 to 8 wt.%.

7. The flame retardant organic resin composition according to any one of Claims 1 - 5, wherein the total amount of aryl groups in all substituents of component (B) is within the range of 20 to 100 mole %.

8. The flame retardant organic resin composition according to any one of Claims 1 - 7, wherein the weight-average molecular weight of component (B) is within the range of 300 to 10,000.

9. The flame retardant organic resin composition according to Claim 1, wherein component (C) is a diorganopolysiloxane having the general formula;

R⁵ ₃-SiO(R⁶ ₂SiO)_n-SiR⁵ ₃ where R⁵ is a substituted group selected from a monovalent hydrocarbon group, an alkoxy group, or a hydroxyl group; R⁶ is a monovalent hydrocarbon where the content of methyl group is 50 mole % or more.

10. The flame retardant organic resin composition of Claim 1 , wherein component (C) is an organopolysiloxane containing epoxy group and the epoxy group is bonded to a silicon atom as γ-glycidoxypropyl group.

11. The flame retardant organic resin composition according to Claim 1 , wherein component (C) is a diorganopolysiloxane having an epoxy group and the epoxy group is bonded to a silicon atom as γ-glycidoxypropyl group.

12. The flame retardant organic resin composition according to any one of Claims 1 to 9, further comprising

(D) 0.01 to 1 parts by weight an alkali metal salt of an organic acid or an organic acid ester or an alkali-earth metal salt of an organic acid or an organic acid ester.

3. The flame retardant organic resin composition according to any of Claims 1 to 10, further comprising

(E) 0.01 to 5 parts by weight a fluororesin powder.