JP4863627B2 - Light-reflective flame retardant polycarbonate resin composition with excellent thermal stability - Google Patents

Description

  The present invention is excellent in flame retardancy, impact resistance, workability, surface appearance, etc., in which a specific polytetrafluoroethylene-containing mixed powder, titanium oxide, a silicone compound, and an organometallic salt compound are blended. The present invention relates to a polycarbonate resin composition that takes into account the influence on the light, and a light reflector formed from the composition. The resin composition according to the present invention can be suitably used particularly for a light reflecting plate such as a liquid crystal backlight.

  Polycarbonate resin is a thermoplastic resin excellent in impact resistance, heat resistance, and the like, and is widely used in fields such as electric / electronics, machinery, automobiles, and building materials. Among these, in order to meet safety requirements in the fields of electricity and electronics including OA, in addition to the above-described excellent performance possessed by the polycarbonate resin, a material excellent in flame retardancy is required.

  Conventionally, flame retardants such as organic bromine compounds and phosphorus compounds have been used, but recently various flame retardant methods using silicone flame retardants have been proposed in order to consider the environmental impact more. It is being adopted.

  However, in order to satisfy the high flame retardancy such as V-0 based on the US Underwriters Laboratories (UL) standard 94, the flame retardant only with the silicone flame retardant is of course insufficient. In order to prevent this, it has been proposed and practiced to incorporate a polytetrafluoroethylene resin.

Japanese Patent Laid-Open No. 60-23442 JP 60-260647 A JP-A-61-57645

  On the other hand, in applications of light reflectors, particularly light reflectors for liquid crystal backlights, materials having both flame retardancy and light reflectivity have been used by blending titanium oxide or the like with flame retardant polycarbonate resin. .

  In a light-reflective flame-retardant polycarbonate resin material in which a silicone-based flame retardant, polytetrafluoroethylene resin, titanium oxide, or the like is blended with a polycarbonate resin, a relatively large amount of titanium oxide is blended to impart light reflectivity. There was a need. Furthermore, this titanium oxide accelerates the hydrolysis of the polycarbonate resin due to the thermal history received during granulation and molding, and promotes the decrease in the molecular weight of the polycarbonate resin and the occurrence of silver streaks on the surface of the molded product. There was a problem of deteriorating the appearance.

  There is also a problem that the surface appearance is deteriorated due to the polytetrafluoroethylene resin used. This is because the polytetrafluoroethylene resin itself easily aggregates during the granulation process of the polycarbonate resin composition. This is caused by poor feedability to the extruder barrel and poor dispersion of the resin, and only the deterioration of the surface appearance. There are problems such as a drop in impact strength and flame retardancy, and these improvements have been demanded.

  The inventor does not sacrifice the impact resistance, which is a feature of polycarbonate resin, and is extremely excellent in workability and surface appearance at the time of granulation processing, and also in thermal stability considering the influence on the environment. As a result of repeated studies to obtain an excellent light-reflective flame-retardant polycarbonate resin composition, the present invention has been achieved.

  That is, in the present invention, the polytetrafluoroethylene-containing mixed powder (B) is 0.01 to 2 parts by weight per 100 parts by weight of the polycarbonate resin (A), and the sediment density in the methylene chloride is 1.1 g / cc or more. 5 to 25 parts by weight of titanium oxide (C), the main chain has a branched structure and the organic functional group contained is composed of an aromatic group, or composed of an aromatic group and a hydrocarbon group (excluding the aromatic group). A light-reflective flame-retardant polycarbonate resin composition excellent in heat stability, characterized by comprising 0.01 to 2 parts by weight of a silicone compound (D) and 0.005 to 2 parts by weight of an organometallic salt (E), and The present invention provides a light reflecting plate or a light reflecting plate for a liquid crystal backlight.

  The light-reflective flame retardant polycarbonate resin composition with excellent thermal stability according to the present invention does not contain halogen flame retardants or phosphorus flame retardants composed of chlorine, bromine compounds, etc. Furthermore, it has not only high flame retardancy and light reflectivity, but also excellent thermal stability, surface appearance and mechanical strength, and is particularly suitable as a material for light reflectors for liquid crystal backlight applications. Can be used.

  The present invention is described in detail below.

  The polycarbonate resin (A) used in the present invention is obtained by a phosgene method in which various dihydroxydiaryl compounds and phosgene are reacted, or a transesterification method in which a dihydroxydiaryl compound and a carbonate such as diphenyl carbonate are reacted. A typical example of the polymer is a polycarbonate resin produced from 2,2-bis (4-hydroxyphenyl) propane (bisphenol A).

  Examples of the dihydroxydiaryl compound include bisphenol 4-, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2, 2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxyphenyl-3-methylphenyl) propane, 1,1-bis (4-hydroxy-3) -Tert-butylphenyl) propane, 2,2-bis (4-hydroxy-3-bromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis ( Bis (hydroxyaryl) alkanes such as 4-hydroxy-3,5-dichlorophenyl) propane, 1,1- (4-hydroxyphenyl) cyclopentane, bis (hydroxyaryl) cycloalkanes such as 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3 Dihydroxy diaryl ethers such as 3,3'-dimethyldiphenyl ether, dihydroxy diaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxy-3,3 ' Dihydroxy diaryl sulfoxides such as dimethyldiphenyl sulfoxide, dihydroxy diary such as 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone Sulfone, and the like.

  You may use these individually or in mixture of 2 or more types. In addition to these, piperazine, dipiperidyl hydroquinone, resorcin, 4,4'-dihydroxydiphenyl, and the like may be mixed and used.

  Furthermore, the above dihydroxyaryl compound and a trivalent or higher phenol compound as shown below may be used in combination. Trihydric or higher phenols include phloroglucin, 4,6-dimethyl-2,4,6-tri- (4-hydroxyphenyl) -heptene, 2,4,6-dimethyl-2,4,6-tri- (4 -Hydroxyphenyl) -heptane, 1,3,5-tri- (4-hydroxyphenyl) -benzol, 1,1,1-tri- (4-hydroxyphenyl) -ethane and 2,2-bis- [4 4- (4,4'-dihydroxydiphenyl) -cyclohexyl] -propane and the like.

  The viscosity average molecular weight of the polycarbonate resin (A) is usually 10,000 to 100,000, preferably 15,000 to 35,000. In producing such a polycarbonate resin, a molecular weight regulator, a catalyst and the like can be used as necessary.

  The polytetrafluoroethylene-containing mixed powder (B) used in the present invention is composed of polytetrafluoroethylene particles having a particle diameter of 10 μm or less and an organic polymer. The particle diameter of the polytetrafluoroethylene is as follows. Is more than 10 μm and is not agglomerated.

Furthermore, from the viewpoint of dispersibility when blended with a polycarbonate resin, in a dispersion obtained by mixing an aqueous dispersion of polytetrafluoroethylene particles having a particle diameter of 0.05 to 1.0 μm and an aqueous dispersion of organic polymer particles. A polymer obtained by polymerizing a vinyl monomer and then pulverizing by coagulation or spray drying is preferred. The polytetrafluoroethylene particle aqueous dispersion can be obtained by polymerizing a tetrafluoroethylene monomer by emulsion polymerization using a fluorine-containing surfactant.

  Fluorine-containing olefins such as hexafluoropropylene, chlorotrifluoroethylene, fluoroalkylethylene, and perfluoroalkyl vinyl ether as copolymerization components in the emulsion polymerization of polytetrafluoroethylene particles as long as the properties of polytetrafluoroethylene are not impaired. Fluorine-containing alkyl (meth) acrylates such as perfluoroalkyl (meth) acrylate can be used. The content of the copolymer component is preferably 10% by weight or less with respect to tetrafluoroethylene.

  Commercially available raw materials for polytetrafluoroethylene particle dispersions include: Fullon AD-1 and AD-936 manufactured by Asahi Glass Fluoropolymer, Polyflon D-1 and D-2 manufactured by Daikin Industries, and Teflon manufactured by Mitsui Dupont Fluorochemical A typical example is 30J.

  The organic polymer particle aqueous dispersion used for obtaining the polytetrafluoroethylene-containing mixed powder (B) can be obtained by polymerizing a vinyl monomer by a known method such as emulsion polymerization.

  The vinyl monomer used to obtain the organic polymer particle aqueous dispersion, or the polytetrafluoroethylene particle aqueous dispersion having a particle diameter of 0.05 to 1.0 μm and the organic polymer particle aqueous dispersion were mixed. Although it does not restrict | limit especially as a vinyl monomer polymerized in a dispersion liquid, it is a thing with high affinity with a polycarbonate resin (A) from a dispersible viewpoint at the time of mix | blending with a polycarbonate resin (A). Preferably there is.

  Specific examples of these vinyl monomers include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, t-butylstyrene, o-ethylstyrene, p-chlorostyrene, o-chlorostyrene, 2, Aromatic vinyl monomers such as 4-dichlorostyrene, p-methoxystyrene, o-methoxystyrene, 2,4-dimethylstyrene; methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, Butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, cyclohexyl acrylate, cyclohexane methacrylate (Meth) acrylic acid ester monomers such as xylyl; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; α, β-unsaturated carboxylic acids such as maleic anhydride; N-phenylmaleimide, N-methylmaleimide, Maleimide monomers such as N-cyclohexylmaleimide; Epoxy group-containing monomers such as glycidyl methacrylate; Vinyl ether monomers such as vinyl methyl ether and vinyl ethyl ether; Vinyl carboxylates such as vinyl acetate and vinyl butyrate Body; α-olefin monomers such as ethylene, propylene, and isobutylene; and diene monomers such as butadiene, isoprene, and dimethylbutadiene. These monomers may be used alone or in admixture of two or more.

  Among these monomers, one or more selected from the group consisting of aromatic vinyl monomers and vinyl cyanide monomers is preferable from the viewpoint of affinity with the polycarbonate resin (A). Mention may be made of monomers containing 30% by weight or more of monomers. Particularly preferred is a monomer containing 30% by weight or more of one or more monomers selected from the group consisting of styrene and acrylonitrile.

  The content ratio of polytetrafluoroethylene in the polytetrafluoroethylene-containing mixed powder (B) is preferably 0.1% by weight to 90% by weight. If it is less than 0.1% by weight, the effect of improving flame retardancy is insufficient, and if it exceeds 90% by weight, the surface appearance may be adversely affected.

  For the polytetrafluoroethylene-containing mixed powder (B), the aqueous dispersion is poured into hot water in which a metal salt such as calcium chloride or magnesium sulfate is dissolved, salted out, solidified and then dried, or spray dried. Can be pulverized.

  While ordinary polytetrafluoroethylene fine powder becomes an aggregate of 100 μm or more in the process of recovering as a powder from the state of a particle dispersion, it is difficult to uniformly disperse it in a thermoplastic resin. The polytetrafluoroethylene-containing mixed powder (B) used in the present invention is extremely excellent in dispersibility in the polycarbonate resin (A) because the polytetrafluoroethylene alone does not form a domain having a particle diameter exceeding 10 μm. ing. As a result, in the polycarbonate resin composition of the present invention, polytetrafluoroethylene is efficiently made into fine fibers in the polycarbonate, and it has excellent flame retardancy and excellent surface appearance and impact characteristics.

  The compounding quantity of polytetrafluoroethylene containing mixed powder (B) is 0.01-2 weight part per 100 weight part of polycarbonate resin (A). If it is less than 0.01 parts by weight, the effect of preventing dripping is inferior and the flame retardancy is lowered, which is not preferable. On the other hand, when the amount exceeds 2 parts by weight, the impact resistance is lowered and the surface appearance is deteriorated. A preferable blending amount is 0.1 to 1.5 parts by weight, more preferably 0.6 to 1.0 parts by weight.

It is a requirement that the sediment density of the titanium oxide (C) used in the present invention in methylene chloride is 1.1 g / cc or more. The sediment density is determined by the following equation.
Precipitated bulk density in methylene chloride (g / cc)
= (Weight of dissolved titanium oxide (g)) ÷ (titanium oxide precipitation volume after 48 hours (cc)) The titanium oxide precipitation volume after 48 hours in the formula (cc) is a predetermined amount of oxidation using a graduated cylinder. Titanium is dissolved in methylene chloride, and the volume of precipitated titanium oxide after 48 hours is determined.

  When the sediment density in methylene chloride is less than 1.1 g / cc, the dispersibility of titanium oxide in the polycarbonate resin (A) is poor, and as a result, silver streaks occur and the appearance of the molded product is inferior. . It is more preferable to use titanium oxide having a sediment density of 1.2 g / cc or more in methylene chloride.

  Titanium oxide (C) may be produced by either chlorine method or sulfuric acid method, and the crystal form may be either rutile type or anatase type. As the particle size of titanium oxide, those having a particle size of about 0.1 to 0.5 μm can be suitably used. Further, it is said that the dispersibility of the inorganic filler such as titanium oxide is superior in the dispersibility in the resin when the sediment density is higher in the solvent having a polarity close to that of the resin used. Therefore, titanium oxide having a large sediment density in methylene chloride, which is a good solvent for the polycarbonate resin (A), is preferably used.

  The compounding quantity of a titanium oxide (C) is 5-25 weight part per 100 weight part of polycarbonate resin (A). When the blending amount is less than 5 parts by weight, the light reflectivity is inferior, and when it exceeds 25 parts by weight, the appearance and flame retardancy are deteriorated. More preferably, it is the range of 9-16 weight part.

Examples of the silicone compound (D) in which the main chain has a branched structure and the organic functional group consists of an aromatic group, or consists of an aromatic group and a hydrocarbon group (excluding an aromatic group) include the following general formula (1) As shown in
General formula (1)

  In the general formula (1), R1, R2 and R3 represent main chain organic functional groups, and X represents a terminal functional group.

The silicone compound (D) is characterized by having T units (RSiO _1.5 ) and / or Q units (SiO _2.0 ) as branching units. These preferably contains more than 20 mol% of the total siloxane units _{(R 3~0 SiO 2~0.5).} (R represents an organic functional group.) Further, the silicone compound (D) preferably contains 20 mol% or more of aromatic groups among the organic functional groups contained therein.

  The aromatic group contained is phenyl, biphenyl, naphthalene or a derivative thereof, but a phenyl group can be preferably used.

  Of the organic functional groups in the silicone compound (D) attached to the main chain or branched side chain, the organic group other than the aromatic group is preferably a hydrocarbon group having 4 or less carbon atoms, and preferably a methyl group. Can be used. Further, the terminal group is preferably one kind selected from methyl group, phenyl group and hydroxyl group, or a mixture of these two kinds to three kinds.

  The average molecular weight (weight average) of the silicone compound (D) is preferably 3000 to 500000, and more preferably 5000 to 270000.

  The compounding quantity of a silicone compound (D) is 0.01-2 weight part per 100 weight part of polycarbonate resin (A). If the blending amount is out of the range, the flame retardant effect is insufficient in any case, which is not preferable. More preferably, it is the range of 0.05-1.0 weight part.

  Examples of the organic metal salt (E) used in the present invention include an aromatic sulfonic acid metal salt and a perfluoroalkanesulfonic acid metal salt. Preferably, 4-methyl-N- (4-methyl) is used. Phenyl) sulfonyl-benzenesulfonamide potassium salt, potassium diphenylsulfone-3-sulfonate, potassium diphenylsulfone-3-3′-disulfonate, sodium paratoluenesulfonate, potassium perfluorobutanesulfonate, and the like can be used.

  The compounding amount of the organic metal salt (E) is 0.005 to 2 parts by weight per 100 parts by weight of the polycarbonate resin (A). If the blending amount is less than 0.005 parts by weight, the flame retardancy is lowered, which is not preferable. On the other hand, if it exceeds 2 parts by weight, problems such as failure to obtain mechanical properties and flame retardancy and deterioration of the surface appearance are undesirable. More preferably, it is the range of 0.1-1 weight part.

  In the present invention, when the components (A), (B), (C), (D), and (E) are mixed, the form and order are not limited. For example, a method of adding (B), (C), (D), (E) in a powder state to a polycarbonate resin (A) in an organic solvent solution, powder, pellet state, or a molten polycarbonate resin (A) And a method of adding (B), (C), (D), and (E) in a powder state. In addition, a method of mixing all the components at once with a tumbler, a ribbon blender, a high-speed mixer, or the like, or a method of once mixing arbitrary components with these mixers and then blending the remaining components. Furthermore, a master batch in which the polycarbonate resin (A) and the polytetrafluoroethylene-containing mixed powder (B) are mixed is prepared in advance, and then the master batch and the polycarbonate resins (A) and (C), (D) , (E) and the like can be mixed in a desired composition. These mixtures are easily melt-kneaded and pelletized using a normal single-screw or twin-screw extruder.

  The polycarbonate resin composition of the present invention contains a known additive such as a phenol-based or phosphorus-based heat stabilizer [2,6-di-t-butyl-4-methylphenol, 2- (1-methylcyclohexyl) -4. , 6-Dimethylphenol, 4,4'-thiobis- (6-tert-butyl-3-methylphenol), 2,2-methylenebis- (4-ethyl-6-tert-methylphenol), n-octadecyl-3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate, tris (2,4-di-t-butylphenyl) phosphite, 4,4'-biphenylenediphosphinic acid tetrakis- (2,4- Di-t-butylphenyl), etc.], UV absorber [pt-butylphenyl salicylate, 2,2'-dihydroxy-4-methoxybenzophenone, 2- 2'-hydroxy-4'-n-octoxyphenyl) benzotriazole, etc.], lubricant [paraffin wax, n-butyl stearate, synthetic beeswax, natural beeswax, glycerin monoester, montanic acid wax, polyethylene wax, pentaerythritol tetra Stearate etc.], filler [calcium carbonate, clay, silica, glass fiber, glass sphere, glass flake, carbon fiber, talc, mica, various whiskers, etc.], fluidity improver [monophosphate ester such as triphenyl phosphate, etc. Examples include oligomeric condensed phosphoric ester. ], Additives [epoxidized soybean oil, liquid paraffin, etc.], and other thermoplastic resins such as polyamide, polyethylene terephthalate, polybutylene terephthalate, amorphous polyester, polyphenylene ether, polymethyl methacrylate, and various impact resistances An improver (for example, rubber reinforced resin obtained by graft polymerization of a compound such as methacrylic acid ester, styrene, or acrylonitrile on rubber such as polybutadiene, polyacrylic acid ester or ethylene / propylene rubber) is required. Can be added accordingly.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. “Parts” are based on weight unless otherwise specified.

Details of the materials used in the examples are as follows.
Polycarbonate resin:
-Caliber 200-20 manufactured by Sumitomo Dow (molecular weight: 18600)
(Hereafter abbreviated as PC)
Polytetrafluoroethylene:
・ Mitsubrene A3800 manufactured by Mitsubishi Rayon Co., Ltd.
(Polytetrafluoroethylene-containing mixed powder (PTFE content: 50%))
(Hereinafter abbreviated as PTFE-1)
・ Neiflon FA500, manufactured by Daikin Industries, Ltd.
(Normal polytetrafluoroethylene resin)
(Hereafter, abbreviated as PTFE-2)
Titanium oxide:
・ Kronos 2230 manufactured by Kronos
(Precipitated bulk density in methylene chloride: 1.3 g / cc)
(Hereinafter abbreviated as TiO2-1)
・ RCL-4 manufactured by Millennium Chemical
(Sedimentation density in methylene chloride: 1.0 g / cc)
(Hereafter abbreviated as TiO2-2)
-RC-69 made by Millennium Chemical
(Precipitated bulk density in methylene chloride: 0.7 g / cc)
(Hereinafter abbreviated as TiO2-3)
Organic metal salt (hereinafter abbreviated as metal salt):
Sodium paratoluenesulfonate

Silicone compound (hereinafter abbreviated as Si flame retardant):
The silicone compound was produced according to a general production method. That is, a silicone compound partially condensed by dissolving an appropriate amount of diorganodichlorosilane, monoorganotrichlorosilane and tetrachlorosilane, or a partially hydrolyzed condensate thereof in an organic solvent, adding water and hydrolyzing it. Then, triorganochlorosilane was added and reacted to terminate the polymerization, and then the solvent was separated by distillation or the like. The structural characteristics of the silicone compound synthesized by the above method are as follows:
・ D / T / Q unit ratio of main chain structure: 40/60/0 (molar ratio)
-Ratio of phenyl group in all organic functional groups (*): 60 mol%
-Terminal group: methyl group only-Weight average molecular weight (**): 15,000
*: The phenyl group is first contained in the T unit in the silicone containing the T unit, and the remaining D group is contained in the D unit. When the phenyl group is attached to the D unit, the one attached is preferential, and when the phenyl group remains, two are attached. Except for the terminal group, the organic functional group is a methyl group except for the phenyl group.
**: Weight average molecular weight is two significant digits.

  As a blending method, the above-mentioned various raw materials are collectively put in a tumbler at the blending ratio shown in Table 2, and after 10 minutes of dry mixing, a melting temperature is 280 ° C. using a 37 mm twin screw extruder (Kobe Steel KTX37). And kneaded to obtain pellets of polycarbonate resin composition.

  From the obtained pellets, using an injection molding machine (Japan Steel Works J100E-C5) under the condition of a melting temperature of 280 ° C., a test piece for ASTM physical property evaluation and a test piece for UL94 flammability evaluation (1. 0 mm thickness), a three-stage plate for evaluating light reflectivity and surface appearance was prepared.

The evaluation methods are as follows.
1. Flame retardance:
The flammability was evaluated according to the following UL94V vertical combustion test method. The test piece is left for 48 hours in a temperature-controlled room with a temperature of 23 ° C. and a humidity of 50%. Was evaluated. UL94V is a method for evaluating flame retardance from the afterflame time and drip properties after indirect flames of a burner for 10 seconds on a test piece of a predetermined size held vertically, and is divided into the following classes: .

  The after-flame time shown in Table 1 is the length of time that the specimen keeps flaming combustion after the ignition source is moved away. The ignition of cotton by drip is about 300 mm below the lower end of the specimen. It is determined by whether a certain marking cotton is ignited by a drip from the specimen. The criterion for evaluation was V-1 or higher in the 1.0 mm thickness test.

2. Light reflectivity:
A three-stage plate (thickness 3, 2, 1 mm) test piece having a length of 90 mm and a width of 40 mm was prepared, and a Y value at a wavelength of 400 to 800 nm was measured with a spectrophotometer (Murakami Color Research Laboratory CMS- 35SP). A sample having a Y value of 94% or more was regarded as acceptable.

3. Impact resistance:
The notched Izod impact strength was measured according to ASTM D-256, and an impact value of 30 kg · cm / cm or more was regarded as acceptable. Thickness is 3.2 mm.

4). Surface appearance Create a three-stage plate (thickness 3, 2, 1 mm) specimen with a length of 90 mm and a width of 40 mm, and visually check the surface appearance (silver streak and surface roughness (pinhole generation)). Observed.

5. Surface appearance after retention Using the obtained pellets, a three-stage plate was evaluated for 10 minutes by using an injection molding machine (J100E-C5 manufactured by Nippon Steel Works) under the condition of a melting temperature of 300 ° C. and evaluating the surface appearance. It was prepared and the presence or absence of occurrence of silver streaks on the surface of the molded product was visually observed.

  Table 2 Mixing ratio and evaluation results

表面外観の判定： ○：無し ×：有り
＊：塩化メチレン中の沈降カサ密度

Judgment of surface appearance: ○: None ×: Present *: Precipitated bulk density in methylene chloride

  As shown in Examples 1 to 3, for the essential components of the present invention and those satisfying the specified value range of the blending amount of each component, flame retardancy, light reflectivity, impact strength, surface appearance (silver streak and rough skin And the performance standards such as silver streak after dwelling) were satisfied.

  On the other hand, as shown in Comparative Examples 1 to 5, those which do not satisfy the specified value range of the blending amount of the essential component and each blending component of the present invention had the following drawbacks.

In Comparative Example 1, since the sediment density of the titanium oxide of the present invention in methylene chloride was lower than claimed, the surface appearance after residence due to lack of thermal stability was poor.
In Comparative Example 2, since the sediment density in the methylene chloride of the titanium oxide of the present invention was lower than the claimed range, the surface appearance after residence due to the lack of thermal stability was further inferior.
In Comparative Example 3, since the blending amount of the polytetrafluoroethylene-containing mixed powder of the present invention was less than the lower limit of the specified range, the flame retardancy and the surface appearance after residence were inferior.
In Comparative Example 4, since the blending amount of the polytetrafluoroethylene-containing mixed powder of the present invention is larger than the upper limit of the specified range, the impact strength is reduced and the surface appearance and the surface appearance after residence are inferior. .
In Comparative Example 5, since ordinary polytetrafluoroethylene resin was used instead of the polytetrafluoroethylene-containing mixed powder of the present invention, impact strength was reduced, and surface appearance (occurrence of rough skin) and surface after staying The appearance was inferior.

Claims (6)

  Titanium oxide (C) having a polytetrafluoroethylene-containing mixed powder (B) of 0.01 to 2 parts by weight per 100 parts by weight of the polycarbonate resin (A) and a sediment density in methylene chloride of 1.1 g / cc or more. 5 to 25 parts by weight, a silicone compound (D) 0 in which the main chain has a branched structure and the organic functional group contained is an aromatic group or an aromatic group and a hydrocarbon group (excluding an aromatic group) A light-reflective flame-retardant polycarbonate resin composition excellent in thermal stability, characterized by comprising 0.01 to 2 parts by weight and an organometallic salt (E) 0.005 to 2 parts by weight.   The polytetrafluoroethylene-containing mixed powder (B) is composed of polytetrafluoroethylene particles having a particle diameter of 10 μm or less and an organic polymer, and the particle diameter of the polytetrafluoroethylene exceeds 10 μm and is not an aggregate. The light-reflective flame-retardant polycarbonate resin composition having excellent thermal stability according to claim 1.   A light-reflective flame-retardant polycarbonate resin composition excellent in thermal stability, wherein the precipitated bulk density of titanium oxide (C) in methylene chloride is 1.2 g / cc or more.   The light-reflective flame-retardant polycarbonate resin excellent in heat stability according to claim 1, wherein the organic metal salt (E) is a metal salt of an aromatic sulfonic acid or a metal salt of a perfluoroalkanesulfonic acid. Composition.   The light reflection board formed using the light-reflective flame-retardant polycarbonate resin composition excellent in the thermal stability of any one of Claims 1-4. The light reflecting plate according to claim 5, wherein the light reflecting plate is a light reflecting plate for a liquid crystal backlight.