CN111094452A

CN111094452A - Flame-retardant polycarbonate resin composition

Info

Publication number: CN111094452A
Application number: CN201880054907.2A
Authority: CN
Inventors: 坂口惠子
Original assignee: Sumika Polycarbonate Ltd
Current assignee: Sumika Polycarbonate Ltd
Priority date: 2017-09-06
Filing date: 2018-08-01
Publication date: 2020-05-01
Also published as: WO2019049563A1; JP7307679B2; JPWO2019049563A1; TW201930460A; KR20200039669A

Abstract

The present invention provides a novel polycarbonate resin composition which can provide a polycarbonate resin composition molded article having excellent flame retardancy, mechanical strength and appearance. The present invention relates to a flame-retardant polycarbonate resin composition comprising (A) a polycarbonate, (B) at least one flame retardant selected from the group consisting of silicone flame retardants, halogen flame retardants and phosphate flame retardants, (C) polytetrafluoroethylene and (D) an elastomer, wherein the flame retardant (B) content, the polytetrafluoroethylene (C) content and the elastomer (D) content in the composition are 0.001 to 40 mass%, 0.1 to 1.0 mass%, respectively.

Description

Flame-retardant polycarbonate resin composition

Technical Field

The present invention relates to a flame retardant polycarbonate resin composition.

Background

Polycarbonate resin compositions are widely used in the fields of electric, electronic, ITE, machinery, automobiles, building materials, and the like because of their excellent transparency, flame retardancy, heat resistance, mechanical strength, and the like. In recent years, higher flame retardancy has been demanded in these fields, and for example, in the evaluation of flame retardancy according to the UL94 test (flammability test of plastic material for parts of equipment) prescribed by underwriters laboratories, U.S. Inc., high flame retardancy suitable for V-0 and V-1 has been demanded.

In order to cause the polycarbonate resin composition to exhibit such high flame retardancy, it is necessary that dripping (grip) of the resin does not occur during burning. As a means for suppressing resin dripping during combustion, a fluororesin such as Polytetrafluoroethylene (PTFE) is blended in the polycarbonate resin composition. However, when a fluororesin such as polytetrafluoroethylene is blended in a polycarbonate resin composition, there is a problem that the fluororesin is aggregated and fluororesin particles float on the surface of a molded article of the polycarbonate resin composition, which deteriorates the appearance.

As a method for solving such a problem, for example, patent document 1 discloses the following technique: a polycarbonate resin is blended with a flame retardant and polytetrafluoroethylene, and further, as the polytetrafluoroethylene, a polytetrafluoroethylene produced by suspension polymerization is used. However, this method also fails to sufficiently solve the following problem of deterioration in appearance: that is, in the polycarbonate resin composition, polytetrafluoroethylene aggregates, polytetrafluoroethylene particles float on the surface of a molded article of the polycarbonate resin composition to form streaky lines, or the color tone of the surface varies. In the extremely thin injection molded article specified in the UL-94 standard, PTFE is further fibrillated by strong shear at the time of injection molding, and the diameter of the thickest part of the fibril is 2 μm or less in a narrow visual field, but the surface appearance of the molded article cannot be sufficiently improved.

In recent years, molded articles of polycarbonate resin compositions are required to have excellent flame retardancy and further excellent appearance, but the method disclosed in patent document 1 has a problem that excellent flame retardancy and excellent appearance required for polycarbonate resin compositions cannot be achieved at the same time. If the appearance can be improved, there are many advantages in that the number of processes is reduced because coating, surface coating, or the like is not required, and thus, the demand for further improvement of the appearance is increasing.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2010-106097

Disclosure of Invention

Problems to be solved by the invention

The purpose of the present invention is to provide a novel polycarbonate resin composition that can provide a polycarbonate resin composition molded article having excellent flame retardancy, mechanical strength, and appearance.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems and as a result, have found that a flame-retardant polycarbonate resin composition containing a polycarbonate, a specific flame retardant, polytetrafluoroethylene, and an elastomer can maintain excellent flame retardancy by containing a specific amount of a specific flame retardant, polytetrafluoroethylene, and an elastomer, and can effectively suppress appearance deterioration (formation of streaky lines and color variation in which a fluororesin floats on the surface of a molded article) which cannot be avoided in a conventional polycarbonate resin composition containing polytetrafluoroethylene, thereby completing the present invention.

That is, the present invention relates to a flame-retardant polycarbonate resin composition comprising (a) a polycarbonate, (B) at least one flame retardant selected from the group consisting of silicone flame retardants, halogen flame retardants, and phosphate flame retardants, (C) polytetrafluoroethylene, and (D) an elastomer, wherein the flame retardant (B) content, the polytetrafluoroethylene (C) content, and the elastomer (D) content in the composition are 0.001 to 40 mass%, 0.1 to 1.0 mass%, and 1.5 mass%, respectively.

The elastomer (D) is preferably at least one selected from the group consisting of a methyl methacrylate-butadiene-styrene copolymer, a methyl methacrylate-butadiene copolymer, a styrene-butadiene triblock copolymer, a styrene-isoprene triblock copolymer, and an olefin thermoplastic elastomer.

It is preferable that (E) at least one thermoplastic resin selected from the group consisting of styrene-acrylonitrile copolymer, polymethacrylylstyrene, polyester, polyamide and ethylene-vinyl acetate polymer is further contained.

The content of the thermoplastic resin (E) is preferably 0.005 to 5% by mass in the flame retardant polycarbonate resin composition.

The resin composition for testing is prepared without blending the elastomer (D) in the resin composition, and the diameter of the coarsest part of the fibrils of the polytetrafluoroethylene (C) present in any visual field of 127 μm × 95 μm is preferably 2 μm or less, by observing a fracture surface obtained by freeze-breaking the resin composition for testing in a direction perpendicular to the flow direction with a scanning electron microscope.

The number of foreign matter of 50 μm or more present in a molded article of 80mm × 52mm × 2mm obtained by injection molding of the flame-retardant polycarbonate resin composition is preferably 10 or less.

The average particle diameter of the polytetrafluoroethylene (C) is preferably 200 μm or less.

The thermoplastic resin (E) preferably has an average particle diameter of 5 μm or less.

The present invention also relates to a resin molded article obtained by molding the flame retardant polycarbonate resin composition.

ADVANTAGEOUS EFFECTS OF INVENTION

The flame-retardant polycarbonate resin composition of the present invention contains a polycarbonate, a specific flame retardant, polytetrafluoroethylene, and an elastomer, and contains a specific amount of the specific flame retardant, polytetrafluoroethylene, and elastomer, so that when the polycarbonate resin composition is used for molding, the flame-retardant polycarbonate resin composition can effectively suppress the appearance deterioration which cannot be avoided in the conventional polycarbonate resin composition containing polytetrafluoroethylene while maintaining excellent flame retardancy. As a result, the amount of polytetrafluoroethylene (C) blended can be reduced and the appearance can be improved, if the flame retardancy is the same.

Detailed Description

The present invention will be described in detail below by showing embodiments, examples and the like, but the present invention is not limited to the embodiments, examples and the like shown below, and can be arbitrarily modified in practice within a range not departing from the gist of the present invention.

The flame-retardant polycarbonate resin composition of the present invention is a flame-retardant polycarbonate resin composition comprising (A) a polycarbonate, (B) at least one flame retardant selected from the group consisting of silicone flame retardants, halogen flame retardants and phosphate flame retardants, (C) polytetrafluoroethylene and (D) an elastomer, and is characterized in that the content of the flame retardant (B) in the composition is 0.001 to 40 mass%, the content of the polytetrafluoroethylene (C) is 0.1 to 1.0 mass%, and the content of the elastomer (D) is 1.5 mass% or less.

< compounding ingredients >

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

Examples of the dihydroxydiaryl compound include bis (hydroxyaryl) alkanes such as bis (4-hydroxyphenyl) methane, 1-bis (4-hydroxyphenyl) ethane, 2-bis (4-hydroxyphenyl) butane, 2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2-bis (4-hydroxyphenyl-3-methylphenyl) propane, 1-bis (4-hydroxy-3-tert-butylphenyl) propane, 2-bis (4-hydroxy-3-bromophenyl) propane, 2-bis (4-hydroxy-3, 5-dibromophenyl) propane, 2-bis (4-hydroxy-3, 5-dichlorophenyl) propane, bis (hydroxyaryl) alkanes other than bisphenol A, 1, 1-bis (4-hydroxyphenyl) cyclopentane, bis (hydroxyaryl) cycloalkanes such as 1, 1-bis (4-hydroxyphenyl) cyclohexane, dihydroxy diaryl ethers such as 4,4 ' -dihydroxy diphenyl ether, 4 ' -dihydroxy-3, 3 ' -dimethyl diphenyl ether, dihydroxy diaryl sulfides such as 4,4 ' -dihydroxy diphenyl sulfide, dihydroxy diaryl sulfoxides such as 4,4 ' -dihydroxy-3, 3 ' -dimethyl diphenyl sulfoxide, dihydroxy diaryl sulfones such as 4,4 ' -dihydroxy diphenyl sulfone, 4 ' -dihydroxy-3, 3 ' -dimethyl diphenyl sulfone, and the like.

These may be used alone or in combination of two or more, and in addition thereto, piperazine, dipiperidinohydroquinone, resorcinol, 4' -dihydroxydiphenyl and the like may be used in combination.

Further, a phenolic compound having a valence of 3 or more shown below may be used in combination with the dihydroxyaryl compound. Examples of the phenolic compound having a valence of 3 or more include phloroglucinol, 4, 6-dimethyl-2, 4, 6-tris- (4-hydroxyphenyl) -heptene, 2,4, 6-dimethyl-2, 4, 6-tris- (4-hydroxyphenyl) -heptane, 1,3, 5-tris- (4-hydroxyphenyl) benzene, 1,1, 1-tris- (4-hydroxyphenyl) -ethane, and 2, 2-bis [4,4- (4, 4' -dihydroxydiphenyl) -cyclohexyl ] -propane.

The viscosity average molecular weight (Mv) of the polycarbonate (A) is not particularly limited, but is preferably 10000 to 100000, preferably 15000 to 35000, from the viewpoint of moldability and strength, and when the polycarbonate is produced, a molecular weight modifier, a catalyst and the like may be used as required, and it is to be noted that the viscosity average molecular weight (Mv) of the polycarbonate is a value calculated by preparing a 0.5 mass% methylene chloride solution, measuring the specific viscosity (η sp) at 20 ℃ using a Cannon-Fenske type viscometer, obtaining the intrinsic viscosity [ η ] by concentration conversion, and calculating the intrinsic viscosity by the SCHNELL equation described below.

[η]＝1.23×10^-4×Mv^0.83

The proportion of the polycarbonate contained in the flame-retardant polycarbonate resin composition of the present invention is preferably 50 to 99.5 mass%, more preferably 70 to 99.5 mass%, and still more preferably 85 to 99.5 mass%, from the viewpoint of imparting excellent flame retardancy, mechanical strength, and excellent appearance to the polycarbonate resin composition.

The form of the polycarbonate (A) is not particularly limited, and examples thereof include granular materials, flake materials, beads, and the like. Among these, from the viewpoint of obtaining uniform dispersibility, a flake-like material is preferable, and a porous flake-like material is more preferable. The bulk density of the polycarbonate is also not particularly limited, but is preferably 0.1 to 0.9, more preferably 0.1 to 0.7. Here, the bulk density is a value measured according to a compacted apparent bulk density of JIS K7370. The size of the polycarbonate is not particularly limited, but is preferably 5mm or less.

The flame retardant (B) used in the present invention is at least one selected from the group consisting of a silicone flame retardant, a halogen flame retardant, and a phosphate flame retardant. Silicone flame retardants are particularly preferred in terms of exhibiting excellent flame retardancy and excellent appearance. As the silicone flame retardant, for example, a silicone compound having a branched main chain and an aromatic group in an organic functional group is preferable as described in Japanese patent laid-open No. 11-217494.

More specifically, a substance having a branched structure in the main chain and an aromatic group as an organic functional group, that is, a substance having a T unit and/or a Q unit as a branched unit is preferable.

[ CHEM 1 ]

(Here, R is₁、R₂And R₃Represents an organic functional group of the main chain, and X represents a functional group at the end. l, m and n are integers of 1 or more. )

The content of these is preferably 20 mol% or more of the total siloxane units. If the amount is less than 20 mol%, the heat resistance of the silicone compound is lowered, the flame retardancy effect is lowered, and the viscosity of the silicone compound itself is too low, which may adversely affect the kneading property with the polycarbonate or the moldability. More preferably 30 mol% or more and 95 mol% or less. When the amount is 30 mol% or more, the heat resistance of the silicone compound is further improved, and the flame retardancy of the polycarbonate resin containing the silicone compound is greatly improved. However, if the amount exceeds 95 mol%, the degree of freedom of the main chain of the silicone decreases, and condensation of aromatic groups during combustion may be difficult to occur, and it may be difficult to exhibit remarkable flame retardancy.

In addition, the aromatic group is preferably 20 mol% or more of the organic functional groups of the silicone compound. If the amount is less than this range, condensation of aromatic groups is less likely to occur during combustion, and the flame-retardant effect may be reduced. More preferably 40 to 95 mol%. When the amount is 40 mol% or more, the aromatic group during combustion can be condensed more efficiently, and the dispersibility of the silicone compound in the polycarbonate resin (a) is greatly improved, whereby an extremely good flame retardant effect can be exhibited. If the amount exceeds 95 mol%, condensation may be difficult to occur due to steric hindrance of the aromatic groups, and a significant flame retardant effect may not be exhibited.

The aromatic group is a phenyl group, biphenyl, naphthalene, or a derivative thereof, and a phenyl group is preferable from the viewpoint of safety of the silicone compound. Among the organic functional groups attached to the main chain or the branched side chain in the silicone compound, the organic group other than the aromatic group is preferably a methyl group, and the organic functional group as the terminal group is preferably 1 selected from methyl, phenyl, hydroxyl, alkoxy (particularly methoxy), or a mixture of 2 to 4 selected therefrom. In the case of these terminal groups, since reactivity is low and gelation (crosslinking) of the silicone compound is less likely to occur at the time of kneading the polycarbonate resin (a) and the silicone compound, the silicone compound can be uniformly dispersed in the polycarbonate resin (a), and as a result, a more favorable flame retardant effect can be obtained, and moldability can be improved. Methyl is particularly preferred. In this case, since the reactivity is extremely low, the dispersibility is extremely good, and the flame retardancy can be further improved.

The silicone compound preferably has a weight average molecular weight of 5000 to 500000. If the amount is less than 5000, the heat resistance of the silicone compound itself is lowered, the flame retardancy effect is lowered, the melt viscosity is too low, and the silicone compound may bleed out onto the surface of the molded article of the polycarbonate resin (a) during molding to deteriorate the moldability; when the amount exceeds 500000, the melt viscosity increases, the uniform dispersion in the polycarbonate resin (A) is impaired, and the flame retardancy effect and moldability may be lowered. More preferably 10000 to 270000. In the case where the melt viscosity of the silicone compound is within this range, the silicone compound can be dispersed in the polycarbonate resin (a) extremely uniformly, and there is no excessive bleeding on the surface, and therefore, more excellent flame retardancy and moldability can be achieved.

The proportion of the flame retardant (B) contained in the flame-retardant polycarbonate resin composition of the present invention is 0.001 to 40% by mass in view of imparting excellent flame retardancy and excellent appearance to the polycarbonate resin composition. The silicone flame retardant is preferably 0.05 to 5% by mass.

As the flame retardant (B), a halogen-based flame retardant or a phosphate-based flame retardant may be used. Examples of the halogen-based flame retardant include polycarbonate comprising tetrabromobisphenol a [2, 2-bis (3, 5-dibromo-4-hydroxyphenyl) propane ], copolycarbonate of tetrabromobisphenol a and bisphenol a, decabromodiphenyl ether, octabromodiphenyl ether, hexabromodiphenyl ether, tetrabromodiphenyl ether, hexabromocyclododecane, ethylenebistetrabromophthalimide, tris (pentabromobenzyl) isocyanurate, brominated polystyrene, tetrabromobisphenol a-epoxy resin, and the like. Examples of the phosphate-based flame retardant include phenyl resorcinol polyphosphate, tolyl resorcinol polyphosphate, phenyl hydroquinone polyphosphate, tolyl hydroquinone polyphosphate, phenyl 2, 2-bis (4-hydroxyphenyl) propane (: bisphenol A type) polyphosphate, tolyl 2, 2-bis (4-hydroxyphenyl) propane (: bisphenol A type) polyphosphate, phenyl tolyl 2, 2-bis (4-hydroxyphenyl) propane (: bisphenol A type) polyphosphate, xylyl resorcinol polyphosphate, phenyl, p-tert-butylphenyl resorcinol polyphosphate, phenylisopropylphenyl resorcinol polyphosphate, tolyl resorcinol polyphosphate, tolylresorcinol polyphosphate, and the like, Phenyl isopropyl phenyl diisopropyl phenyl resorcinol polyphosphate, and the like. These compounds are commercially available, for example, CR741, CR733S, PX-200, and the like, manufactured by Daihuai chemical industries, Inc. The proportion of each flame retardant (B) is more preferably 5 to 35% by mass. The phosphate-based flame retardant is preferably 3 to 25 mass%.

The polytetrafluoroethylene (C) used in the present invention is not particularly limited, and a polytetrafluoroethylene homopolymer may be used, or a copolymer or terpolymer containing the polytetrafluoroethylene property to the extent that the copolymer or terpolymer does not impair the polytetrafluoroethylene property may be used. Further, the polytetrafluoroethylene may be a copolymer.

The form of the polytetrafluoroethylene (C) is not particularly limited, but is preferably a particle. The average particle diameter is preferably 200 μm or less, more preferably 100 μm or less. When the particle diameter is 200 μm or less, excellent flame retardancy and excellent appearance can be imparted. Here, as for the average particle diameter, 50ml of methylene chloride was added to 1g of the composite resin particles, the mixture was left at 23 ℃ for 3 hours, the obtained solution was stirred with a stirrer for 20 minutes, the major diameter and the minor diameter were measured with respect to 100 PTFE particles remaining undissolved, and the average particle diameter was the average of the particle diameters of 100 PTFE particles with (major diameter + minor diameter)/2 as the particle diameter.

There are commercially available PTFE-containing additives (for example, a3800 manufactured by mitsubishi yang corporation and SN3307 manufactured by Shine Polymer corporation) that can be used for adding polytetrafluoroethylene particles to a polycarbonate resin composition, but the average particle diameter of the additives measured by the above-mentioned measurement method is not 200 μm or less.

The polytetrafluoroethylene (C) is preferably used in the form of an aqueous dispersion from the viewpoint of relatively uniform dispersibility, that is, from the viewpoint of reducing the generation of aggregates of polytetrafluoroethylene and being excellent in uniform dispersibility and reproducibility. The solid content of the polytetrafluoroethylene (C) in the aqueous dispersion is not particularly limited, but is preferably 20 to 65 mass%, more preferably 20 to 70 mass%.

The content of the polytetrafluoroethylene (C) in the flame-retardant polycarbonate resin composition of the present invention is 0.1 to 1.0 mass%, more preferably 0.1 to 0.5 mass%, from the viewpoint of imparting excellent flame retardancy and excellent appearance to the polycarbonate resin composition.

The polytetrafluoroethylene (C) is preferably used in the form of composite resin particles premixed with polycarbonate resin particles, because polytetrafluoroethylene particles having a low affinity for the polycarbonate resin composition can be dispersed in the polycarbonate resin composition with high uniformity. When the composite resin particles are mixed into the polycarbonate resin composition, and the polycarbonate resin particles in the composite resin particles are melted in the polycarbonate resin composition, the polytetrafluoroethylene particles are dispersed in the polycarbonate resin composition with high uniformity, and the aggregation of the polytetrafluoroethylene particles during mixing can be effectively inhibited. In addition, when the composite particles contain a thermoplastic resin, the affinity with the polycarbonate resin composition is further improved by the effect of the thermoplastic resin, and dispersion with higher uniformity can be achieved. This can effectively suppress deterioration in appearance of the polycarbonate resin composition containing polytetrafluoroethylene particles (streaky lines formed by floating the fluororesin on the surface of the molded article, variation in surface color, and the like).

The average particle diameter of the polycarbonate resin particles used in the composite resin particles is not particularly limited, but is preferably 5mm or less, more preferably 3mm or less, from the viewpoint of imparting excellent flame retardancy and excellent appearance to the polycarbonate resin composition. By providing the polycarbonate resin particles with such a particle diameter, the composite resin particles of the present invention can be easily uniformly dispersed in the polycarbonate resin composition.

The bulk density of the polycarbonate resin pellets is 0.1 to 0.9, and more preferably 0.1 to 0.7. If the amount is less than 0.1 or exceeds 0.9, the uniform dispersion state cannot be expressed, or the material feeding during processing becomes unstable. The bulk density herein refers to a value measured by compacting the apparent bulk density according to JIS K7370.

The proportion of the polycarbonate resin particles contained in the composite resin particles is preferably 0 to 99.5 mass%, more preferably 70 to 99.5 mass%, and even more preferably 85 to 99.5 mass%, from the viewpoint of imparting excellent flame retardancy, mechanical strength, and excellent appearance to the polycarbonate resin composition.

The proportion of the polytetrafluoroethylene particles contained in the composite resin particles is preferably 0.1 to 33 mass%, more preferably 0.2 to 25 mass%, and even more preferably 3 to 15 mass%, from the viewpoint of imparting excellent flame retardancy, mechanical strength, and excellent appearance to the polycarbonate resin composition.

Such composite resin particles can be suitably produced by a method including, for example, the following steps.

Step 1: the aqueous dispersion of polytetrafluoroethylene particles is mixed with the aqueous dispersion of thermoplastic resin particles to prepare a mixed dispersion.

And a step 2: the polycarbonate resin particles and the mixed dispersion are mixed.

The details (the kind of resin, the particle diameter, and the like) of the polytetrafluoroethylene particles, the thermoplastic resin particles, and the polycarbonate resin particles are as described above. The content of the composite resin particles of the present invention may be adjusted with respect to the mixing ratio thereof.

In step 1, as the aqueous dispersion of polytetrafluoroethylene particles and the aqueous dispersion of thermoplastic resin particles, for example, commercially available products can be used. The solid content in the aqueous dispersion of polytetrafluoroethylene particles is usually 20 to 65% by mass. The solid content in the aqueous dispersion of thermoplastic resin particles is usually 20 to 70% by mass.

In step 1, the aqueous dispersion of polytetrafluoroethylene particles and the aqueous dispersion of thermoplastic resin particles may be mixed by using a stirrer or the like. In the preparation of a mixed dispersion of these resin particles, the pH may be adjusted by using an acid or an alkali.

In step 2, the polycarbonate resin pellets and the mixed dispersion may be mixed by using a general mixer (e.g., a nauta mixer, a henschel mixer, a butterfly mixer, etc.), a homogenizer, a stirrer, or the like.

After the step 2, a drying step is preferably provided. Examples of the drying means include various drying means such as hot air drying, vacuum drying, steam drying, rotary drying, and suction drying.

The elastomer (D) used in the present invention is not particularly limited, and is preferably a graft copolymer obtained by graft-copolymerizing a rubber component with a monomer component copolymerizable therewith. The graft copolymer may be produced by any of bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, and the like, and the copolymerization method may be one-step grafting or multi-step grafting.

The glass transition temperature of the rubber component is usually 0 ℃ or lower, more preferably-20 ℃ or lower, and still more preferably-30 ℃ or lower, and specific examples of the rubber component include polybutadiene rubber, polyisoprene rubber, polyalkyl acrylate rubber such as polybutyl acrylate or poly (2-ethylhexyl acrylate), butyl acrylate-2-ethylhexyl acrylate copolymer, silicone rubber such as polyorganosiloxane rubber, butadiene-acrylic composite rubber, IPN (interpenetrating polymer network) type composite rubber composed of polyorganosiloxane rubber and polyalkyl acrylate rubber, styrene-butadiene rubber, ethylene-propylene rubber or ethylene-butylene rubber, ethylene- α -olefin rubber such as ethylene-octene rubber, ethylene-acrylic rubber, and fluororubber, and among these, from the viewpoint of mechanical properties and surface appearance, polybutadiene rubber, polyalkyl acrylate rubber, polyorganosiloxane rubber, IPN type composite rubber composed of polyorganosiloxane rubber and polyalkyl acrylate rubber, and styrene-butadiene rubber are preferable.

Specific examples of the monomer component graft-copolymerizable with the rubber component include aromatic vinyl compounds, vinyl cyanide compounds, (meth) acrylate compounds, (meth) acrylic acid compounds, (meth) glycidyl (meth) acrylate and other epoxy group-containing (meth) acrylate compounds, maleimide compounds such as maleimide, N-methylmaleimide and N-phenylmaleimide, α -unsaturated carboxylic acid compounds such as maleic acid, phthalic acid and itaconic acid, and anhydrides thereof (for example, maleic anhydride) and the like, and among these, from the viewpoint of mechanical properties and surface appearance, aromatic vinyl compounds, vinyl cyanide compounds, (meth) acrylate compounds and (meth) acrylic acid compounds are preferable, and (meth) acrylate compounds are more preferable, and specific examples of the (meth) acrylate compounds include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate and octyl (meth) acrylate.

The elastomer (D) used in the present invention is preferably a core/shell type graft copolymer type elastomer in view of impact resistance and surface appearance. Among them, particularly preferred is a core/shell type graft copolymer having a core layer of at least one rubber component selected from the group consisting of polybutadiene-containing rubbers, polybutyl acrylate-containing rubbers, polyorganosiloxane rubbers, and IPN type composite rubbers composed of polyorganosiloxane rubbers and polyalkyl acrylate rubbers, and including a shell layer formed by copolymerizing (meth) acrylic acid esters around the core layer. The core/shell type graft copolymer preferably contains 40% by weight or more of the rubber component, and more preferably 60% by weight or more. The (meth) acrylic acid is preferably contained in an amount of 10% by weight or more. The core/shell type in the present invention does not necessarily need to clearly distinguish between the core layer and the shell layer, and widely includes compounds obtained by graft-polymerizing a rubber component around a portion to be the core.

Preferable specific examples of the core/shell type graft copolymer include methyl methacrylate-butadiene-styrene copolymer (MBS), methyl methacrylate-acrylonitrile-butadiene-styrene copolymer (MABS), methyl methacrylate-butadiene copolymer (MB), methyl methacrylate-acrylic rubber copolymer (MA), methyl methacrylate-acrylic rubber-styrene copolymer (MAs), methyl methacrylate-acrylic acid-butadiene rubber copolymer, methyl methacrylate-acrylic acid-butadiene rubber-styrene copolymer, methyl methacrylate- (acrylic acid-silicone IPN rubber) copolymer, silicone-acrylic composite rubber containing polyorganosiloxane and polyalkyl (meth) acrylate, and the like, particularly preferred are silicone-acrylic composite rubbers comprising polyorganosiloxane and polyalkyl (meth) acrylate, and methyl methacrylate-butadiene copolymer (MB). These rubbery polymers may be used alone in 1 kind, or 2 or more kinds may be used in combination.

The elastomer (D) used in the present invention preferably includes methyl methacrylate-butadiene-styrene copolymer (MBS resin), methyl methacrylate-butadiene copolymer, styrene-butadiene triblock copolymer known as SBS or SEBS and hydrogenated product thereof, styrene-isoprene triblock copolymer known as SPS or SEPS and hydrogenated product thereof, olefin thermoplastic elastomer known as TPO, polyester elastomer, silicone rubber, acrylate rubber, and the like, and more preferably methyl methacrylate-butadiene-styrene copolymer, methyl methacrylate-butadiene copolymer, styrene-butadiene triblock copolymer, styrene-isoprene triblock copolymer, and olefin thermoplastic elastomer.

Examples of such elastomers (D) include "Paraloid (registered trademark, the same shall apply hereinafter)" EXL2602 "," Paraloid EXL2603 "," Paraloid EXL2655 "," Paraloid EXL2311 "," Paraloid EXL2313 "," Paraloid EXL2315 "," Paraloid KM330 "," Paraloid KM336P "," Paraloid KCZ201 ", and" METABLEN (registered trademark, the same shall apply hereinafter) C-223A ", manufactured by Rohm and Haas Japan, "METABLEN E-901", "METABLEN S-2001", "METABLEN SRK-200", "METABLENS-2030", "Kane Ace (registered trademark, the same as below) M-511", "Kane Ace M-600", "Kane Ace M-400", "Kane Ace M-580", "Kane Ace M-711", "Kane Ace MR-01", and "UBESTA XPA" manufactured by Yu Yongji Co., Ltd.

The proportion of the elastomer (D) contained in the flame-retardant polycarbonate resin composition of the present invention is 1.5% by mass or less, preferably 0.1% by mass to 1.5% by mass. When the amount exceeds 1.5% by mass, the heat resistance and flame retardancy are poor. On the other hand, if the amount is 0.1 part by mass or more, deterioration in appearance (streaky line formation and color variation caused by floating of the fluororesin on the surface of the molded article) can be effectively suppressed.

In addition to the components (A) to (D), the flame retardant polycarbonate resin composition of the present invention may be blended with various components which are generally blended with a flame retardant polycarbonate resin composition. Examples of such components include various resins, other flame retardants, antioxidants, fluorescent brighteners, colorants, fillers, antiblocking agents, ultraviolet absorbers, antistatic agents, softeners, spreading agents (liquid paraffin, epoxidized soybean oil, etc.), other organic metal salts, and the like.

As the various resins, known resins blended in the polycarbonate resin composition can be blended. Examples of the various resins include polystyrene, high impact polystyrene, ABS, AES, AAS, AS, acrylic resin, polyamide, polyethylene terephthalate, polybutylene terephthalate, polyarylate, polysulfone, and polyphenylene sulfide resin. These resins may be used alone or in combination of two or more.

As the antioxidant, a known antioxidant blended in the polycarbonate resin composition can be used. Examples of the antioxidant include a phosphorus antioxidant, a phenol antioxidant, and the like. Among them, a hindered phenol-based antioxidant is preferably used, and examples thereof include pentaerythritol tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], thiodiethylene-bis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], and the like. The compounding amount of the antioxidant is, for example, 0.005 to 1 part by mass based on 100 parts by mass of the polycarbonate resin.

As the colorant, a known colorant compounded in the polycarbonate resin composition can be used. The colorant is not particularly limited, and a dye or a pigment (titanium dioxide, carbon black, or the like) can be used. The amount of the colorant to be blended is, for example, 0.0001 to 10 parts by mass per 100 parts by mass of the polycarbonate resin.

As the filler, a known filler blended in the polycarbonate resin composition can be used. The filler is not particularly limited, and examples thereof include glass fiber, carbon fiber, silica, talc, and mica. The amount of the filler is preferably 3 to 120 parts by mass per 100 parts by mass of the polycarbonate resin.

As the organic metal salt, a known organic metal salt compounded in the polycarbonate resin composition can be used. The organic metal salt is not particularly limited, and examples thereof include an aromatic sulfur compound metal salt, a perfluoroalkane sulfonic acid metal salt, and the like. Examples of the metal of the organic sulfonic acid metal salt include alkali metals and alkaline earth metals. The amount of the organic metal salt to be mixed is preferably 0.001 to 5 parts by mass, more preferably 0.003 to 3 parts by mass, per 100 parts by mass of the polycarbonate resin.

The flame retardant polycarbonate resin composition of the present invention preferably has a rating of V-0 or V-1 when a vertical burning test (V test) of UL-94 standard (flammability test of plastic material for parts of equipment) is performed using a test piece having a thickness of 1.5 mm.

The resin composition for testing is prepared without blending the elastomer used in the present invention in the resin composition, and the diameter of the coarsest part of the fibrils of polytetrafluoroethylene (C) present in any visual field of 127 μm × 95 μm is preferably 2 μm or less, when the fracture surface obtained by freeze-fracturing the resin composition for testing in the direction perpendicular to the flow direction is observed with a scanning electron microscope.

The direction (TD direction) perpendicular to the flow direction of the resin composition means a direction perpendicular to the flow direction of the resin in the resin particles. The dispersion state of the polytetrafluoroethylene (C) in the particles can be understood by observing a cross section perpendicular to the flow direction. Specifically, in order to prevent the dispersion state of the polytetrafluoroethylene (C) from changing, the particles are cooled to an extremely low temperature by liquid nitrogen or the like, and the polycarbonate as the matrix resin is subjected to brittle fracture, whereby the dispersion state of the fibrillated polytetrafluoroethylene (C) is observed. Without cooling, the polycarbonate was fractured tenaciously and covered with polytetrafluoroethylene (C), and fibrils could not be observed. The field of view for observation was observed in a wide range of 127 μm × 95 μm in order to confirm the overall state. The number of visual fields to be observed is not particularly limited, and for example, it is preferable to observe fracture surfaces of 3 or more particles. When 3 particles were observed, no fibrils of polytetrafluoroethylene (C) having a diameter of more than 2 μm in the thickest part were present, and almost no aggregation of polytetrafluoroethylene (C) was observed as a whole, and high flame retardancy was exhibited.

When the polytetrafluoroethylene (C) is dispersed in uneven thickness, the diameter of the thickest part (the maximum width in the short axis direction) is used. The diameter of the coarsest portion of the fibrils is 2 μm or less, preferably 1 μm or less. When the diameter of the thickest part exceeds 2 μm, streaky lines are formed, or the color tone of the surface is uneven, whereby the appearance is deteriorated. When the particle diameter is 2 μm or less, PTFE is further fibrillated and dispersed favorably in an extremely thin injection molded article prescribed by the UL-94 standard due to strong shear during injection molding.

The number of white foreign matters present in a molded article of 80mm × 52mm × 2mm obtained by injection molding the flame retardant polycarbonate resin composition of the present invention is preferably 10 or less, more preferably 5 or less. If there are 11 or more, the surface tends to be rough and the appearance tends to be poor. Here, the white foreign matter was determined by observing the injection-molded article with the naked eye and an optical microscope, and counting the foreign matter of 50 μm or more present in the entire molded article.

The method for producing the polycarbonate resin composition of the present invention is not particularly limited, and for example, the polycarbonate resin composition can be produced by a production method comprising: a step of premixing a polycarbonate (A) and a polytetrafluoroethylene (C) to obtain a premix; and a step of melt-kneading the obtained premix with the polycarbonate (A), the flame retardant (B) and the elastomer (D) to obtain a melt-kneaded product; or the manufacturing method comprises: a step of premixing polycarbonate (A), flame retardant (B) and polytetrafluoroethylene (C) to obtain a premix; and a step of melt-kneading the obtained premix with the polycarbonate (A) and the elastomer (D) to obtain a melt-kneaded product. According to these methods, polytetrafluoroethylene can be dispersed well in polycarbonate, and the fibril diameter can be reduced.

< premixing step >

The premixing refers to the preparation of a master batch by mixing the polycarbonate (a) and the polytetrafluoroethylene (C) before melt kneading. The flame retardants (B) may be premixed together as required. The mixing method is not particularly limited, and examples thereof include a method of mixing an aqueous dispersion of a polycarbonate (a) and a polytetrafluoroethylene (C) in a solid state; dry blending in which the polycarbonate (a) and the polytetrafluoroethylene (C) are mixed in a solid state, and the like. Among these, a method of mixing an aqueous dispersion of the polycarbonate (a) and the polytetrafluoroethylene (C) in a solid state is preferable from the viewpoint of obtaining uniform dispersibility. The mixing means is not particularly limited, and it is preferable to mix the components while stirring, and a general mixer (for example, nauta mixer, henschel mixer, butterfly mixer, etc.), homogenizer, stirrer, etc. can be used. In addition, when preparing a mixed dispersion of these resin particles, the pH may be adjusted using an acid or a base.

The amount of the polytetrafluoroethylene (C) to be mixed in the premixing step is not particularly limited, but is preferably 0.1 to 33 parts by mass, more preferably 0.2 to 25 parts by mass, and still more preferably 3 to 15 parts by mass, based on 100 parts by mass of the polycarbonate (a) used in the premixing step. When the flame retardant (B) is further premixed, the amount of the flame retardant (B) to be mixed is not particularly limited, and is preferably 0.005 to 100 parts by mass, more preferably 0.01 to 80 parts by mass, based on 100 parts by mass of the polycarbonate (a) used in the premixing step.

In the pre-mixing step, the thermoplastic resin (E) may be mixed together with the polycarbonate (a) and the polytetrafluoroethylene (C), or the polytetrafluoroethylene (C) and the thermoplastic resin (E) may be mixed in advance and then pre-mixed with the polycarbonate (a) and the elastomer (D). The polytetrafluoroethylene (C) and the thermoplastic resin (E) are preferably used in the form of an aqueous dispersion.

The amount of the thermoplastic resin (E) to be kneaded in the preliminary mixing is also not particularly limited, and is preferably 0.1 to 33 mass%, more preferably 0.2 to 25 mass%, and still more preferably 3 to 20 mass% with respect to 100 parts by mass of the polycarbonate (a) used in the preliminary mixing step.

After the premixing, a drying step is preferably provided. Examples of the drying means include various drying means such as hot air drying, vacuum drying, steam drying, rotary drying, and suction drying.

< melt kneading step >

Melt kneading is melt kneading of the premix obtained in the premix step, the polycarbonate (a), the flame retardant (B), and the elastomer (D). When the flame retardant (B) is mixed in the premixing step, the flame retardant does not need to be kneaded in the melt-kneading step. The kneading method is not particularly limited, and examples thereof include an extruder (melt kneader ), a batch kneader, and the like. The extruder may be a single screw or a multi-screw, and in the case of a multi-screw, a twin-screw extruder such as a intermeshing type co-rotating twin-screw extruder or a multi-screw extruder having two or more screws is preferably used. In general, a common intermeshing type co-rotating twin-screw extruder or the like is preferably used. The kneading temperature is not particularly limited, but is preferably 220 to 340 ℃ and more preferably 240 to 320 ℃. When the temperature is too high exceeding 340 ℃, decomposition of the resin and additives occurs, aggregation of the additives occurs, and appearance of the molded article tends to be poor.

The amount of polycarbonate (a) to be newly blended in the melt-kneading step is not particularly limited, and is preferably 250 to 10000 parts by mass, more preferably 500 to 5000 parts by mass, per 100 parts by mass of the premix. If the mass ratio exceeds 10000, the productivity is poor; when the amount is less than 250 parts by mass, uniform flame retardancy tends to be not obtained.

The amount of the flame retardant (B) added in the melt-kneading step is not particularly limited, and is preferably 0.01 to 40 parts by mass, more preferably 0.01 to 25 parts by mass, further preferably 0.01 to 10 parts by mass, and particularly preferably 0.01 to 5 parts by mass, based on 100 parts by mass of the total of the polycarbonate contained in the preliminary kneaded product and the polycarbonate newly added. When the amount is less than 0.01 part by mass, stable flame retardancy is difficult to obtain; when the amount exceeds 40 parts by mass, the polycarbonate may be decomposed, which may cause production troubles.

The present invention also relates to a resin molded article obtained by molding the flame retardant polycarbonate resin composition. Since the flame-retardant polycarbonate resin composition of the present invention is used, the molded article has less foreign matter and is excellent in flame retardancy, mechanical strength and surface appearance.

The polycarbonate resin composition of the present invention preferably has a rating of V-0 or V-1 when a vertical burning test (V test) of UL-94 standard (flammability test of plastic material for parts of equipment) is performed using a test piece having a thickness of 1.5 mm.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "part" and "%" are based on mass.

Production example 1 production of premix A

An aqueous dispersion of polytetrafluoroethylene particles (primary particle diameter 0.15 to 0.25 μm: POLYFLON D210-C manufactured by Daiki industries, Ltd.) and an aqueous dispersion of styrene-acrylonitrile copolymer particles (primary particle diameter 0.05 to 1 μm: K-1158 manufactured by Japan A & L) were mixed in a ratio of 50: 50 (PTEF pellet: SAN pellet) was mixed at a mass ratio (solid component ratio). The resulting mixed solution is neutralized with an acid to obtain a neutralized mixed solution. Subsequently, 4 parts by mass of a powder of polycarbonate resin pellets (primary particle size of 1mm) was added with a neutralization mixture (solid content: 0.46 parts by mass). Subsequently, the mixture was heated to 80 ℃ and stirred for 0.5 hour by a high speed Mixer (Super Mixer), and then dried to prepare a premix A. The mass ratio of PC resin particles, PTFE particles and SAN particles in premix a was 89.0: 6.5: 6.5. the obtained premix a was measured by the above method and found to have an average particle size of 5mm or less.

< measurement of average particle diameter of PTFE particles >

50ml of methylene chloride was added to 1g of the premix A, and the mixture was left at 23 ℃ for 3 hours. Next, the obtained solution was stirred with a stirrer for 20 minutes, the major axis and the minor axis were measured with respect to 100 PTFE particles remaining undissolved, and the average of the particle diameters of the 100 PTFE particles was defined as the average particle diameter of the PTFE particles, with (major axis + minor axis)/2 being defined as the particle diameter. As a result, the average particle size in the premix A was 70 μm. The minimum value of the short diameter was 9 μm, and the maximum value of the long diameter was 264 μm.

Production example 2 production of premix B

An aqueous dispersion of polytetrafluoroethylene particles (primary particle diameter 0.15 to 0.25 μm: POLYFLON D210-C manufactured by Daiki industries, Ltd.) and an aqueous dispersion of styrene-acrylonitrile copolymer particles (primary particle diameter 0.05 to 1 μm: K-1158 manufactured by Japan A & L) were mixed in a ratio of 65: premix B was produced in the same manner as in production example 1, except that the components were mixed at a mass ratio (solid content ratio) of 35(═ PTEF pellets: SAN pellets). The mass ratio of PC resin particles, PTFE particles and SAN particles in premix B was 89.7: 6.7: 3.6. the obtained premix B was measured by the above method and found to have an average particle size of 5mm or less.

Production example 3 production of premix C

An aqueous dispersion of polytetrafluoroethylene particles (primary particle diameter 0.15 to 0.25 μm: POLYFLON D210-C manufactured by Daiki industries, Ltd.) and an aqueous dispersion of styrene-acrylonitrile copolymer particles (primary particle diameter 0.05 to 1 μm: K-1158 manufactured by Japan A & L) were mixed in a ratio of 35: premix C was produced in the same manner as in production example 1, except that 65 mass ratio (solid content ratio) of PTEF pellet: SAN pellet was mixed. The mass ratio of PC resin particles, PTFE particles and SAN particles in premix C was 82.3: 6.2: 11.5. the premix C obtained was measured by the above method and had an average particle size of 5mm or less.

(examples 1 to 7 and comparative examples 1 to 6)

The components were charged into a tumbler mixer to be dry-mixed for 10 minutes so as to have the compositions shown in Table 1, then kneaded at a melting temperature of 280 ℃ using a twin-screw extruder (TEX 30 α, manufactured by Nippon Steel works, Ltd.) to obtain pellets of the polycarbonate resin compositions, the obtained pellets were injection-molded by an injection molding machine (ROBOSHOT S-2000i, manufactured by FANAC Co., Ltd.), and the obtained molded articles were subjected to the evaluation described later, the details of the components shown in Table 1 are as follows, the premixes A to C were those produced in production examples 1 to 3, and trace amounts of antioxidants (phosphorus-based and phenol-based) and antiblocking agents were added in common to all the examples and comparative examples.

(Components)

● PC: polycarbonate resin (SD POLYCA200-20 manufactured by Sumika Polycarbonate Co., Ltd.: aromatic Polycarbonate resin, bulk density 0.7g/ml)

● flame retardant: a silicone flame retardant (a copolymer of diorganodichlorosilane, monoorganotrichlorosilane, and tetrachlorosilane, having a main chain structure of M/D/T/Q of 14/16/70/0 (molar ratio), a phenyl group ratio of all organic functional groups of 32 mol%, a methyl group as a terminal group, and a weight average molecular weight of about 65000)

● A3800: PTFE/MS (polymethacrylstyrene) 50/50 particles manufactured by Mitsubishi Yang

● SN 3307: PTFE/SAN (styrene-acrylonitrile copolymer) 50/50 pellets manufactured by Shine Polymer Co

● elastomer: core-shell type methylmethacrylate ● butadiene rubber (methylmethacrylate-butadiene copolymer) manufactured by Kane Ace M711 Kaneka

● PTSNa: p-toluenesulfonic acid sodium salt

● C4: perfluorobutylsulfonic acid potassium salt

< measurement of average particle diameter of PTFE particles of A3800 and SN3307 >

The average particle size of PTFE particles was measured for a3800 and SN3307 in the same manner as for the above-described premix a. As a result, the average particle size of A3800 was 317 μm. The minimum value of the short diameter was 82 μm, and the maximum value of the long diameter was 715 μm. On the other hand, SN3307 had an average particle diameter of 253. mu.m. The minimum value of the short diameter was 79 μm, and the maximum value of the long diameter was 633 μm.

< fibril diameter (maximum width in short axis direction) >

Flame-retardant polycarbonate resin composition pellets (for testing) were produced in the same manner as in example 1, except that no elastomer was compounded. After the resulting particles were notched, they were frozen with liquid nitrogen and fractured in a direction perpendicular to the flow direction. The number of fibrils having a diameter (maximum width in the short axis direction) of the thickest part of the fibrils of polytetrafluoroethylene (C) exceeding 2 μm in a visual field of 127. mu. m.times.95 μm was counted by observing the fracture surface with a scanning electron microscope. When 3 particles in total were measured, the evaluation was evaluated as "x" when fibrils exceeding 2 μm were present, and evaluated as good in the absence. These results are shown in table 1. Among the fibrils exposed on the fracture surface of the particle, the maximum width in the short axis direction of the cross section of the fibril was regarded as the fibril diameter.

< evaluation of flame retardancy >

Using the pellets obtained in examples 1 to 8 and comparative examples 1 to 6 in the blending ratios shown in Table 1, a vertical burning test (V test) was carried out on a test piece having a thickness of 1.5mm in accordance with UL-94 standard (flammability test of plastic material for parts of equipment), and the rating was evaluated. The results are shown in Table 1.

< appearance evaluation 1: number of foreign matters >

The pellets obtained in examples 1 to 8 and comparative examples 1 to 6 were dried at 125 ℃ for 4 hours, and then a test piece (80mm × 52mm × 2mm flat plate) was produced by using an injection molding machine (ROBOSHOT S-2000i manufactured by FANAC) under conditions of a temperature of 300 ℃ at the time of molding the test piece, an injection pressure of 100MPa, and a mold temperature of 100 ℃. Next, the visually recognizable region of each test piece was observed visually and with an optical microscope, and the number of foreign substances having a diameter of 50 μm or more was counted. Evaluation was performed according to the following criteria. The results are shown in Table 1.

Good: the number of the foreign matters is 0-5, and the surface is almost not rough;

△ the number of the foreign matters is 6-10, and the surface is slightly rough;

x: the number of foreign matters exceeds 10, and the surface roughness is large.

< appearance evaluation 2: color unevenness of surface >

Compounding of TiO as a colorant₂The polycarbonate resin compositions thus prepared were used as test pieces in the same manner as in examples 1 to 7 and comparative examples 1 to 6, except that the compositions were 1.0 mass% and 0.0025 mass% of carbon black. Specifically, TiO is compounded as a colorant₂The procedure of examples 1 to 8 and comparative examples 1 to 6 was repeated except that the pellets were dried at 125 ℃ for 4 hours, and then a test piece (80mm × 52mm × 2mm flat plate) was produced by using an injection molding machine (ROBOSHOT S-2000i manufactured by FANAC) under conditions of a temperature of 300 ℃ at the time of molding the test piece, an injection pressure of 100MPa, and a mold temperature of 100 ℃. Then, white Light with an illuminance (about 2180Lx/50cm) was irradiated from two directions of 90 ° to one main surface of the test piece using an LED flat lamp (Web LED Photo Light WP-960 manufactured by NanGuing corporation) having a luminous surface of about 170mm × 120mm in a black curtain. A two-dimensional color luminance meter (CA 2000, manufactured by Konika Mendata) was set at a position approximately 10cm from the main surface of the test piece in the vertical direction, and the luminance was measured at 12 positions on the main surface. Using the maximum luminance and the minimum luminance among the obtained luminances and the average luminance at 12 points, the hue deviation ((maximum luminance-minimum luminance)/average luminance) × 100 was calculated. The average of the color tone deviations (%) of 5 test pieces was defined as an average color tone deviation (%). From the obtained average hue deviation (%) results, the color unevenness of the surface was evaluated according to the following criteria. The results are shown in Table 1.

◎, the average hue shift was less than 31.0%, color unevenness was very small, and color unevenness was hardly observed by visual observation.

Good: the average hue shift was 31.0% or more and less than 32.0%, and color unevenness was small, but slight color unevenness was visually observed.

X: the average hue shift was 32.0% or more, and color unevenness was large, and was clearly observed by visual observation.

Industrial applicability

According to the flame retardant polycarbonate resin composition of the present invention, a molded article molded from the obtained resin composition can have both excellent flame retardancy and mechanical strength and excellent appearance, and has many advantages such as no need of coating or surface coating, and therefore, it can be suitably used for applications requiring improvement in appearance, and has an extremely high industrial utility value.

Claims

1. A flame-retardant polycarbonate resin composition comprising (A) a polycarbonate, (B) at least one flame retardant selected from the group consisting of silicone flame retardants, halogen flame retardants and phosphate flame retardants, (C) polytetrafluoroethylene and (D) an elastomer, characterized in that,

the composition contains 0.001 to 40 mass% of a flame retardant (B), 0.1 to 1.0 mass% of polytetrafluoroethylene (C), and 1.5 mass% or less of an elastomer (D).

2. The flame-retardant polycarbonate resin composition according to claim 1, wherein the elastomer (D) is at least one selected from the group consisting of a methyl methacrylate-butadiene-styrene copolymer, a methyl methacrylate-butadiene copolymer, a styrene-butadiene triblock copolymer, a styrene-isoprene triblock copolymer, and an olefin thermoplastic elastomer.

3. The flame retardant polycarbonate resin composition of any one of claims 1 or 2, further comprising (E) at least one thermoplastic resin selected from the group consisting of styrene-acrylonitrile copolymer, polymethacrylylstyrene, polyester, polyamide and ethylene-vinyl acetate polymer.

4. The flame retardant polycarbonate resin composition according to claim 3, wherein the content of the thermoplastic resin (E) is 0.005 to 5% by mass in the flame retardant polycarbonate resin composition.

5. The flame-retardant polycarbonate resin composition according to any one of claims 1 to 4, wherein the resin composition for testing is prepared without blending the elastomer (D) therein, and a fracture surface obtained by freeze-fracturing the resin composition for testing in a direction perpendicular to a flow direction is observed with a scanning electron microscope, and wherein the diameter of the coarsest portion of the fibrils of the polytetrafluoroethylene (C) present in any one visual field of 127 μm x 95 μm is 2 μm or less.

6. The flame-retardant polycarbonate resin composition according to any one of claims 1 to 5, wherein the number of foreign matters having a size of 50 μm or more present in a molded article having a size of 80mm x 52mm x 2mm obtained by injection molding of the flame-retardant polycarbonate resin composition is 10 or less.

7. The flame-retardant polycarbonate resin composition according to any one of claims 1 to 6, wherein the polytetrafluoroethylene (C) has an average particle diameter of 200 μm or less.

8. The flame-retardant polycarbonate resin composition according to any one of claims 4 to 7, wherein the thermoplastic resin (E) has an average particle diameter of 5 μm or less.

9. A resin molded article obtained by molding the flame-retardant polycarbonate resin composition according to any one of claims 1 to 8.