JP6039372B2 - Polybutylene terephthalate resin composition - Google Patents

Description

  The present invention relates to a polybutylene terephthalate resin composition. More specifically, the present invention has excellent impact resistance, flame retardancy and tracking resistance, and has excellent release properties, and warpage of molded products. The present invention relates to a polybutylene terephthalate-based resin composition having no adhesive and a casing or a pedestal part of an electronic device formed by injection molding the same.

  Polybutylene terephthalate has properties suitable as engineering plastics such as excellent heat resistance, moldability, chemical resistance and electrical insulation, so that it is mainly used for injection molding, electrical and electronic parts, automobile parts and other Widely used for electrical parts, machine parts, etc.

  On the other hand, as the field of use of polybutylene terephthalate expands, in addition to the above characteristics, flame safety, that is, flame retardancy is required. As a method for imparting flame retardancy, in general, a flame retardant using a halogen compound or an antimony trioxide (see Patent Document 1) as a flame retardant aid is added to polybutylene terephthalate. The method of converting is well known.

In recent years, electrical and electronic parts and electrical parts have been made thinner and thinner due to the trend toward smaller and lighter devices, and various molded products used for them have also become smaller and thinner. A thin molded product is required to have flame retardancy corresponding to the thinnest part. For example, the flame retardancy of V-0 in the UL-94 standard may be required at a thickness of 0.75 mm. However, achieving a flame retardance becomes more difficult as the molded product becomes thinner.
In the field of electrical and electronic equipment, in addition to flame retardancy, it is necessary to have excellent tracking resistance, which is one of the electrical characteristics, in order to ensure safety against ignition against an electrical load.

Furthermore, polybutylene terephthalate has a problem that its toughness represented by impact strength is insufficient due to its excellent crystal characteristics, and in order to solve this problem, research on polymer alloys has been conducted conventionally. Various proposals have been made for flame retardant formulations.
For example, Patent Document 2 discloses a flame retardant polyester resin composition comprising a polybutylene terephthalate resin, a polycarbonate resin, a halogen flame retardant, a flame retardant assistant, and a transesterification inhibitor as constituents. 3 discloses a flame-retardant polyester resin composition comprising a polybutylene terephthalate resin, a polycarbonate resin, an elastomer, a flame retardant, and a flame retardant aid. Furthermore, Patent Document 4 discloses a polyester resin composition comprising a polyester resin, a polystyrene rubber and a flame retardant.

However, in recent years, the required physical properties have become increasingly sophisticated, and it has become difficult to cope with conventional prescriptions.
For example, in the case of electronic equipment, such as personal computers, servers, sequencers, etc., the thickness of the molded product has become thinner, and in addition to high flame retardancy, it can crack even if dropped. Good impact resistance is required.
Furthermore, excellent mold releasability that does not increase the mold release resistance is also required in injection molding, for example, there is no occurrence of ejector pin marks when taking out from the mold, the surface appearance is good, and warpage is not caused. There is a strong demand for a polybutylene terephthalate-based resin composition capable of producing a non-molded resin molded body (such as a casing).

JP-A-61-66746 JP 2007-314664 A JP-A-6-100713 JP 2005-112994 A

  The object of the present invention is polybutylene terephthalate which has excellent impact resistance, flame retardancy and tracking resistance, has excellent releasability, and does not have a problem of warping of a molded product, and has generally good characteristics. It is in providing a resin-based resin composition.

The inventor has formulated a polycarbonate resin, a specific impact modifier, a specific brominated flame retardant, a specific antimony compound and an anti-drip agent in the polybutylene terephthalate resin in specific amounts, respectively. The inventors have found that a polybutylene terephthalate-based resin composition having excellent impact properties, flame retardancy, tracking resistance, and releasability and having no problem of warping of a molded product can be provided, and the present invention has been completed.
That is, according to the present invention, there are provided the following polybutylene terephthalate resin composition and an electronic device casing or pedestal component formed by injection molding the same.

[1] A) Polybutylene terephthalate resin and (B) polycarbonate resin based on a total of 100 parts by mass of (A) and (B), (A) being 50 to 80 parts by mass, and (B) being 20 to 50 Containing parts by mass,
Furthermore, for a total of 100 parts by mass of (A) and (B),
(C) 5 to 15 parts by mass of an impact modifier containing a butadiene component, (D) 20 to 40 parts by mass of a flame retardant containing at least one selected from brominated epoxy or brominated polycarbonate, (E) 1. A polybutylene terephthalate resin composition comprising 1 to 15 parts by mass of an antimony oxide compound and 0.05 to 1 part by mass of (F) an anti-drip agent.
[2] The polybutylene terephthalate resin composition as described in [1] above, wherein the polycarbonate resin has a viscosity average molecular weight of 20000 or more.
[3] The polybutylene terephthalate resin composition as described in [1] or [2] above, wherein the intrinsic viscosity of the (A) polybutylene terephthalate resin is 0.9 dl / g or more.
[4] A casing or pedestal part of an electronic device obtained by injection molding the polybutylene terephthalate resin composition according to any one of [1] to [3].

  According to the resin composition of the present invention, it is possible to provide a polybutylene terephthalate-based resin composition that is excellent in impact resistance, flame retardancy, tracking resistance, and releasability, and has no problem of warping of a molded product. .

It is a figure which shows the shape of the rectangular parallelepiped box shape molded article used for evaluation of the curvature in an Example.

[Summary of Invention]
The polybutylene terephthalate resin composition of the present invention is
(A) Polybutylene terephthalate-based resin and (B) polycarbonate resin based on a total of 100 parts by mass of (A) and (B), (A) being 50 to 80 parts by mass, and (B) being 20 to 50 parts by mass Contains,
Furthermore, for a total of 100 parts by mass of (A) and (B),
(C) 5 to 15 parts by mass of an impact modifier containing a butadiene component, (D) 20 to 40 parts by mass of a flame retardant containing at least one selected from brominated epoxy or brominated polycarbonate, (E) It contains 1 to 15 parts by mass of antimony oxide and 0.05 to 1 part by mass of (F) anti-drip agent.

Hereinafter, the contents of the present invention will be described in detail.
The description of each constituent element described below may be made based on typical embodiments and specific examples of the present invention, but the present invention is interpreted to be limited to such embodiments and specific examples. It is not a thing. In the specification of the present application, “to” is used in the sense of including the numerical values described before and after it as the lower limit value and the upper limit value.

[(A) Polybutylene terephthalate resin]
The (A) polybutylene terephthalate resin (hereinafter sometimes abbreviated as “PBT resin”), which is the main component of the polybutylene terephthalate resin composition of the present invention, is a terephthalic acid unit and 1,4-butane. A polymer having a structure in which a diol unit has an ester bond is shown. That is, in addition to polybutylene terephthalate resin (homopolymer), polybutylene terephthalate copolymer containing other copolymer components other than terephthalic acid units and 1,4-butanediol units, and homopolymers and copolymers thereof Including the mixture.

  The PBT resin may contain dicarboxylic acid units other than terephthalic acid. Specific examples of other dicarboxylic acids include isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, and 2,5-naphthalenedicarboxylic acid. 2,6-naphthalenedicarboxylic acid, biphenyl-2,2′-dicarboxylic acid, biphenyl-3,3′-dicarboxylic acid, biphenyl-4,4′-dicarboxylic acid, bis (4,4′-carboxyphenyl) methane , Aromatic dicarboxylic acids such as anthracene dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 4,4′-dicyclohexyldicarboxylic acid, and adipic acid , Aliphatic dicarboxylic acids such as sebacic acid, azelaic acid, dimer acid, etc. .

  The diol unit may contain other diol units in addition to 1,4-butanediol. Specific examples of the other diol units include aliphatic or alicyclic diols having 2 to 20 carbon atoms. And bisphenol derivatives. Specific examples include ethylene glycol, propylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, decamethylene glycol, cyclohexanedimethanol, 4,4'-dicyclohexylhydroxymethane. 4,4′-dicyclohexylhydroxypropane, bisphenol A ethylene oxide addition diol, and the like. Furthermore, triols such as glycerin and trimethylolpropane are also included.

  The PBT resin is preferably a polybutylene terephthalate homopolymer obtained by polycondensation of terephthalic acid and 1,4-butanediol. In addition, as a carboxylic acid unit, one or more dicarboxylic acids other than terephthalic acid and / or A polybutylene terephthalate copolymer containing one or more diols other than 1,4-butanediol as the diol unit may be used. In the PBT resin, from the viewpoint of mechanical properties and heat resistance, the proportion of terephthalic acid in the dicarboxylic acid unit is preferably 70 mol% or more, more preferably 90 mol% or more. Similarly, the proportion of 1,4-butanediol in the diol unit is preferably 70 mol% or more, more preferably 90 mol% or more.

  In addition to the above-mentioned bifunctional monomers, trifunctional monomers such as trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, and trimethylolpropane are introduced to introduce a branched structure, and fatty acids are used for molecular weight control. A small amount of a monofunctional compound can be used in combination.

The PBT resin is manufactured by batch polymerization or continuous polymerization of a dicarboxylic acid component mainly composed of terephthalic acid or an ester derivative thereof and a diol component mainly composed of 1,4-butanediol. Can do. In addition, after a low molecular weight polybutylene terephthalate resin is produced by melt polymerization, solid state polymerization can be performed under a nitrogen stream or under reduced pressure to increase the degree of polymerization (or molecular weight) to a desired value.
The PBT resin is preferably obtained by a production method in which a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,4-butanediol as a main component are continuously melt polycondensed.

  The catalyst used in performing the esterification reaction may be a conventionally known catalyst, and examples thereof include a titanium compound, a tin compound, a magnesium compound, and a calcium compound. Of these, titanium compounds are particularly preferred. Specific examples of the titanium compound as the esterification catalyst include titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate.

The PBT resin may be a polybutylene terephthalate resin modified by copolymerization. As a specific preferred copolymer thereof, a polyalkylene glycol (particularly, polytetramethylene glycol (PTMG)) is copolymerized. Examples include polyester ether resins, dimer acid copolymerized polybutylene terephthalate resins, and particularly isophthalic acid copolymerized polybutylene terephthalate resins. These copolymers are those having a copolymerization amount of 1 mol% or more and less than 50 mol% in all segments of the PBT resin. Among them, the copolymerization amount is preferably 2 to 50 mol%, more preferably 3 to 40 mol%, and particularly preferably 5 to 20 mol%.
And the preferable content of these copolymers is 10-100 mass% in the total amount of 100 mass% of (A) polybutylene terephthalate resin, Furthermore, 30-100 mass%, Especially it is 50-100 mass%. is there.

  The intrinsic viscosity ([η]) of the PBT resin is preferably 0.9 dl / g or more. If the intrinsic viscosity is lower than 0.9 dl / g, the resulting resin composition tends to have a low mechanical strength such as impact resistance. The intrinsic viscosity is preferably 1.6 dl / g or less, and more preferably 1.3 dl / g or less. If it is higher than 1.6 dl / g, the fluidity of the resin composition may deteriorate and the moldability may deteriorate. The intrinsic viscosity is measured at 30 ° C. in a 1: 1 (mass ratio) mixed solvent of tetrachloroethane and phenol.

[(B) Polycarbonate resin]
The polybutylene terephthalate resin composition of the present invention contains (B) a polycarbonate resin.
The polycarbonate resin is an optionally branched thermoplastic polymer or copolymer obtained by reacting a dihydroxy compound or a small amount thereof with phosgene or a carbonic acid diester. The production method of the polycarbonate resin is not particularly limited, and a polycarbonate resin produced by a conventionally known phosgene method (interfacial polymerization method) or a melting method (transesterification method) can be used.

  As the raw material dihydroxy compound, an aromatic dihydroxy compound is preferable, 2,2-bis (4-hydroxyphenyl) propane (= bisphenol A), tetramethylbisphenol A, bis (4-hydroxyphenyl) -p-diisopropylbenzene, Hydroquinone, resorcinol, 4,4-dihydroxydiphenyl, etc. are mentioned, Preferably bisphenol A is mentioned. In addition, a compound in which one or more tetraalkylphosphonium sulfonates are bonded to the above aromatic dihydroxy compound can also be used.

  As the polycarbonate resin, among the above-mentioned, aromatic polycarbonate resin derived from 2,2-bis (4-hydroxyphenyl) propane, or 2,2-bis (4-hydroxyphenyl) propane and other aromatic dihydroxy Aromatic polycarbonate copolymers derived from the compounds are preferred. Further, it may be a copolymer mainly composed of an aromatic polycarbonate resin, such as a copolymer with a polymer or oligomer having a siloxane structure. Furthermore, you may mix and use 2 or more types of the polycarbonate resin mentioned above.

  In order to adjust the molecular weight of the polycarbonate resin, a monovalent aromatic hydroxy compound may be used. For example, m- and p-methylphenol, m- and p-propylphenol, p-tert-butylphenol, p-long chain And alkyl-substituted phenols.

  The viscosity average molecular weight (Mv) of the polycarbonate resin is preferably 20000 or more, more preferably 23000 or more and 25000 or more. When a resin having a viscosity average molecular weight lower than 20000 is used, the resulting resin composition tends to have a low mechanical strength such as impact resistance. Moreover, it is preferable that it is 60000 or less, It is more preferable that it is 40000 or less, It is further more preferable that it is 35000 or less. If it is higher than 60000, the fluidity of the resin composition may deteriorate and the moldability may deteriorate.

In the present invention, the viscosity average molecular weight (Mv) of the polycarbonate resin is determined by measuring the viscosity of the methylene chloride solution of the polycarbonate resin at 20 ° C. using an Ubbelohde viscometer, and determining the intrinsic viscosity ([η]). The value calculated from the following Schnell viscosity equation is shown.
[Η] = 1.23 × 10 ⁻⁴ Mv ^0.83

  The method for producing the polycarbonate resin is not particularly limited, and a polycarbonate resin produced by any of the phosgene method (interfacial polymerization method) and the melting method (transesterification method) can also be used. Moreover, the polycarbonate resin which performed the post-process which adjusts the amount of terminal OH groups to the polycarbonate resin manufactured by the melting method is also preferable.

  The content of (B) polycarbonate resin is based on a total of 100 parts by mass of (A) polybutylene terephthalate resin and (B) polycarbonate resin, and (B) polycarbonate resin is 20 to 50 parts by mass, preferably 25 parts by mass. Part or more, more preferably 30 parts by weight or more, preferably 45 parts by weight or less, more preferably 40 parts by weight or less. Below the lower limit, the effect of improving the impact resistance and toughness of the polybutylene terephthalate-based resin composition of the present invention is small, and further, the inner warp of the molded product increases, so that the dimensional characteristics deteriorate. Moreover, when the said lower limit is exceeded, fluidity | liquidity will worsen and a moldability will deteriorate.

[(C) Impact resistance improver containing butadiene component]
As the impact resistance improver containing a butadiene component (C) used in the present invention, a rubber polymer containing at least a butadiene component is copolymerized with a monomer compound that reacts therewith. (C) The glass transition temperature of the impact modifier containing a butadiene component is preferably 0 ° C. or lower, particularly preferably −20 ° C. or lower.

  (C) Specific examples of impact modifiers containing a butadiene component include, for example, acrylonitrile / butadiene copolymer, acrylic / butadiene rubber, and copolymers obtained by polymerizing monomer compounds with these rubbery polymers. Is mentioned. Examples of the monomer compound include aromatic vinyl compounds, vinyl cyanide compounds, (meth) acrylic acid ester compounds, (meth) acrylic acid compounds, and the like. In addition, epoxy group-containing (meth) acrylic acid ester compounds such as glycidyl (meth) acrylate; maleimide compounds such as maleimide, N-methylmaleimide and N-phenylmaleimide; α, β- such as maleic acid, phthalic acid and itaconic acid Examples thereof also include unsaturated carboxylic acid compounds and anhydrides thereof (for example, maleic anhydride). These monomer compounds can be used alone or in combination of two or more.

  (C) The impact modifier containing the butadiene component is preferably of the core / shell type graft copolymer type from the viewpoint of improving the impact resistance, and the rubber polymer containing at least the butadiene component is used as the core layer. A core / shell type graft copolymer comprising a shell layer formed by copolymerizing at least one monomer selected from acrylic acid ester, methacrylic acid ester and aromatic vinyl compound around preferable.

  Examples of core / shell type graft copolymers include methyl methacrylate-butadiene-styrene polymer (MBS), methyl methacrylate-acrylonitrile-butadiene-styrene polymer (MABS), methyl methacrylate-butadiene polymer (MB), methyl Examples thereof include a methacrylate-acrylic / butadiene rubber copolymer and a methyl methacrylate-acrylic / butadiene rubber-styrene copolymer. These rubbery polymers may be used alone or in combination of two or more.

  (C) Content of the butadiene component in the impact modifier containing a butadiene component is preferably 50 to 95% by mass, more preferably 60 to 90% by mass, and further preferably 70 to 85% by mass. When the content of the butadiene component is less than 50% by mass, the impact resistance tends to be inferior, and when it exceeds 90% by mass, the flame retardancy and the weather resistance tend to deteriorate.

  (C) Content of the impact modifier containing a butadiene component is 5-15 mass parts with respect to a total of 100 mass parts of (A) polybutylene terephthalate resin and (B) polycarbonate resin. (C) If the content of the impact modifier containing the butadiene component is less than 5 parts by mass, the effect of improving the impact resistance is small, and if it exceeds 15 parts by mass, the heat resistance and rigidity, as well as the fluidity and flame retardancy. Sex is reduced. The content of the preferable (C) impact modifier is 7 parts by mass or more, 13 parts by mass or less, and further 11 parts by mass or less.

[(D) Flame retardant]
The resin composition of the present invention contains (D) a flame retardant containing at least one selected from brominated epoxy or brominated polycarbonate.
Specific examples of brominated epoxy flame retardants include bisphenol A-type brominated epoxy compounds represented by tetrabromobisphenol A epoxy compounds.

The molecular weight of the brominated epoxy flame retardant is arbitrary and may be appropriately selected and determined, but is preferably 3000 to 100,000 in terms of mass average molecular weight (Mw), and more preferably 15000 to 30000.
The brominated epoxy flame retardant preferably has an epoxy equivalent of 3000 to 40000 g / eq, and particularly preferably 4000 to 10000 g / eq.

  Moreover, a brominated epoxy oligomer can also be used together as a brominated epoxy flame retardant. In this case, for example, by using about 0 to 50% by mass of an oligomer having Mw of 5000 or less, flame retardancy, mold release property and fluidity can be appropriately adjusted. Although the bromine atom content in the brominated epoxy compound is arbitrary, it is usually 10% by mass or more, preferably 20% by mass or more, particularly preferably 30% by mass or more, in order to impart sufficient flame retardancy. The upper limit is 60% by mass, preferably 55% by mass or less.

  Specifically, the brominated polycarbonate flame retardant is preferably a brominated polycarbonate obtained from, for example, brominated bisphenol A, particularly tetrabromobisphenol A. Examples of the terminal structure include a phenyl group, 4-t-butylphenyl group, 2,4,6-tribromophenyl group, etc., and particularly those having a 2,4,6-tribromophenyl group in the terminal group structure. Is preferred.

  The average number of carbonate repeating units in the brominated polycarbonate flame retardant may be appropriately selected and determined, but is usually 2 to 30. If the average number of carbonate repeating units is small, the molecular weight of the (A) polybutylene terephthalate resin may be lowered during melting. On the other hand, if it is too large, the melt viscosity of the polycarbonate resin (B) may increase, causing poor dispersion in the molded body, and the molded body appearance, particularly glossiness, may be reduced. Therefore, the average number of repeating units is preferably 3 to 15, particularly 3 to 10.

  The molecular weight of the brominated polycarbonate-based flame retardant is arbitrary and may be appropriately selected and determined. Preferably, the viscosity average molecular weight is 1000 to 20000, and preferably 2000 to 10,000. In addition, the viscosity average molecular weight of a brominated polycarbonate flame retardant can be calculated | required by the method similar to the measurement of the viscosity average molecular weight of (B) polycarbonate resin.

  The brominated polycarbonate flame retardant obtained from the brominated bisphenol A can be obtained by, for example, a usual method of reacting brominated bisphenol and phosgene. Examples of the end-capping agent include aromatic monohydroxy compounds, which may be substituted with a halogen or an organic group.

  The content of the flame retardant (D) is 20 to 40 parts by mass, preferably 23 parts by mass or more, based on a total of 100 parts by mass of the (A) polybutylene terephthalate resin and the (B) polycarbonate resin. Preferably it is 25 mass parts or more, Preferably it is 36 mass parts or less, More preferably, it is 34 mass parts or less, More preferably, it is 33 mass parts or less. (D) If the content of the flame retardant is too small, the flame retardancy of the resin composition of the present invention becomes insufficient. Conversely, if the content is too large, the mechanical properties and the mold releasability are deteriorated or the flame retardant bleeds out. Will occur.

[(E) Antimony pentoxide compound]
The resin composition of the present invention contains (E) an antimony pentoxide compound.
The antimony-based flame retardant, antimony trioxide _{(Sb 2 O} 3), antimony tetroxide _{(Sb 2 O} 4), there is a diantimony pentoxide _(Sb 2 _{O 5),} etc., in the present invention, antimony pentoxide compound Is used. This is because the antimony pentoxide compound has less influence on the polybutylene terephthalate resin than other antimony compounds, and the decomposition of the resin is suppressed. For this reason, it is possible to suppress a decrease in the crystallization temperature (Tc) of the polybutylene terephthalate resin, and it is difficult to increase the mold release resistance even in the injection molding. A resin molded body can be provided.

  (E) The antimony pentoxide compound may be a double salt of antimony pentoxide and another metal oxide, and the double salt of antimony pentoxide and another metal oxide has excellent GWIT performance (glow wire characteristics). This is also preferable. Specifically, as a double salt of antimony pentoxide and another metal oxide, for example, a double salt represented by the following general formulas (1) to (3) is preferable. These may be used in combination at any ratio.

n (X ₂ O) · Sb ₂ O ₅ · m (H ₂ O) (1)
n (YO) · Sb ₂ O ₅ · m (H ₂ O) (2)
n (Na ₂ O) · Sb ₂ O ₅ (3)
(In these formulas, X represents a monovalent alkali metal element, Y represents a divalent alkaline earth metal element, n represents 0 to 1.5, and m represents 0 to 4. m and n represent formula (1). And in Formula (2), each is determined independently)

In the above formulas (1) to (3), examples of X include lithium, sodium, potassium, and cesium, and examples of Y include calcium, magnesium, and barium. n is larger than 0, usually 0.3 or more, particularly preferably 0.65 to 1.5. If n is too small, the desorption rate of adsorbed water is small, so that the melt viscosity tends to change. Conversely, if n is too large, the amount of antimony will be relatively lowered, and as a flame retardant aid. The effect is reduced.
m is 0-4, preferably 0-2. If m is too large, hydrolysis of the polybutylene terephthalate resin becomes remarkable, which is not preferable.

  (E) The content of the antimony pentoxide compound is 1 to 15 parts by mass, preferably 2 parts by mass or more, with respect to 100 parts by mass in total of (A) polybutylene terephthalate resin and (B) polycarbonate resin. The amount is preferably 3 parts by mass or more, preferably 10 parts by mass or less, more preferably 7 parts by mass or less, still more preferably 6 parts by mass or less, and particularly preferably 5 parts by mass or less. When less than the said lower limit, the flame retardance of the polybutylene terephthalate-type resin composition of this invention will fall. On the other hand, if the lower limit is exceeded, the crystallization temperature is lowered and the releasability is deteriorated, and mechanical properties such as impact resistance are lowered.

[(F) Anti-drip agent]
The resin composition of the present invention contains (F) an anti-drip agent.
(F) As the anti-drip agent, a fluoropolymer is preferable.
As the fluoropolymer, a known polymer having fluorine can be arbitrarily selected and used, and among these, a fluoroolefin resin is preferable.
As fluoroolefin resin, the polymer and copolymer containing a fluoroethylene structure are mentioned, for example. Specific examples thereof include difluoroethylene resin, tetrafluoroethylene resin, tetrafluoroethylene / hexafluoropropylene copolymer resin, and the like. Of these, tetrafluoroethylene resin and the like are preferable. As this fluoroethylene resin, a fluoroethylene resin having a fibril forming ability is preferable.
Examples of the fluoroethylene resin having fibril-forming ability include Mitsui DuPont Fluoro Chemical Co., Ltd., Teflon (registered trademark) 6J, Daikin Industries, Ltd., Polyflon (registered trademark) F201L, Polyflon F103, and the like.

  Examples of the aqueous dispersion of fluoroethylene resin include Teflon (registered trademark) 30J manufactured by Mitsui DuPont Fluorochemical Co., Ltd., Fullon D-1 manufactured by Daikin Chemical Industries, Ltd., and TF1750 manufactured by Sumitomo 3M Co., Ltd. Furthermore, a fluoroethylene polymer having a multilayer structure formed by polymerizing vinyl monomers can also be used as the fluoropolymer. Specific examples thereof include METABRENE (registered trademark) A-3800 manufactured by Mitsubishi Rayon Co., Ltd.

  (F) Content of anti-drip agent is 0.05-1 mass part with respect to a total of 100 mass parts of (A) polybutylene terephthalate resin and (B) polycarbonate resin, Preferably it is 0.1 mass part. More preferably, it is 0.12 parts by mass or more, more preferably 0.15 parts by mass or more, preferably 0.6 parts by mass or less, more preferably 0.45 parts by mass or less, further preferably 0.40 parts by mass. Part or less, particularly preferably 0.35 part by weight or less. (F) If the content of the anti-drip agent is too small, the flame retardancy of the resin composition of the present invention becomes insufficient. Conversely, if the content is too large, the molded article of the resin composition of the present invention has poor appearance and mechanical strength. Decrease occurs.

[Other ingredients]
The resin composition of the present invention may contain various additives as long as the effects of the present invention are not impaired. Such additives include stabilizers, mold release agents (lubricants), nucleating agents, reinforcing fillers, UV absorbers, antistatic agents, antifogging agents, antiblocking agents, plasticizers, dispersing agents, antibacterial agents, etc. Is mentioned.

<Stabilizer>
It is preferable that the resin composition of the present invention further contains a stabilizer because it has effects of improving thermal stability and preventing deterioration of mechanical strength, transparency, and hue. As the stabilizer, a phosphorus stabilizer, a sulfur stabilizer and a phenol stabilizer are preferable.

  Examples of the phosphorus-based stabilizer include phosphorous acid, phosphoric acid, phosphite ester, and phosphate ester. Among them, organic phosphate compounds, organic phosphite compounds, and organic phosphonite compounds are preferable.

The organic phosphate compound is preferably the following general formula:
(R ¹ O) _3-n P (═O) OH _n (4)
(In the formula, R ¹ is an alkyl group or an aryl group, and may be the same or different. N represents an integer of 0 to 2.)
It is a compound represented by these. More preferably, R ¹ is a long-chain alkyl acid phosphate compound having 8 to 30 carbon atoms. Specific examples of the alkyl group having 8 to 30 carbon atoms include octyl group, 2-ethylhexyl group, isooctyl group, nonyl group, isononyl group, decyl group, isodecyl group, dodecyl group, tridecyl group, isotridecyl group, tetradecyl group, A hexadecyl group, an octadecyl group, an eicosyl group, a triacontyl group, etc. are mentioned.

  Examples of the long-chain alkyl acid phosphate include octyl acid phosphate, 2-ethylhexyl acid phosphate, decyl acid phosphate, lauryl acid phosphate, octadecyl acid phosphate, oleyl acid phosphate, behenyl acid phosphate, phenyl acid phosphate, nonyl phenyl acid phosphate Acid phosphate, phenoxyethyl acid phosphate, alkoxy polyethylene glycol acid phosphate, bisphenol A acid phosphate, dimethyl acid phosphate, diethyl acid phosphate, dipropyl acid phosphate, diisopropyl acid phosphate, dibutyl acid phosphate, geo Chill acid phosphate, di-2-ethylhexyl acid phosphate, dioctyl acid phosphate, dilauryl acid phosphate, distearyl acid phosphate, diphenyl acid phosphate, and a bis-nonylphenyl acid phosphate, or the like. Among these, octadecyl acid phosphate is preferable, and this is marketed under the trade name “ADEKA STAB AX-71” of ADEKA.

As the organic phosphite compound, preferably, the following general formula:
^{R 2 O-P (OR 3} ) (OR 4) ··· (5)
(Wherein R ² , R ³ and R ⁴ are each a hydrogen atom, an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 30 carbon atoms, and among R ² , R ³ and R ⁴ ) At least one of them is an aryl group having 6 to 30 carbon atoms.)
The compound represented by these is mentioned.

  Examples of the organic phosphite compound include triphenyl phosphite, tris (nonylphenyl) phosphite, dilauryl hydrogen phosphite, triethyl phosphite, tridecyl phosphite, tris (2-ethylhexyl) phosphite, and tris (tridecyl). ) Phosphite, tristearyl phosphite, diphenyl monodecyl phosphite, monophenyl didecyl phosphite, diphenyl mono (tridecyl) phosphite, tetraphenyldipropylene glycol diphosphite, tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite Hydrogenated bisphenol A phenol phosphite polymer, diphenyl hydrogen phosphite, 4,4′-butylidene-bis (3-methyl-6-t rt-butylphenyldi (tridecyl) phosphite), tetra (tridecyl) 4,4′-isopropylidenediphenyldiphosphite, bis (tridecyl) pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, di Lauryl pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, tris (4-tert-butylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, hydrogenated bisphenol A pentaerythritol phosphite Phytopolymer, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite Phosphite, 2,2'-methylenebis (4,6-di -tert- butylphenyl) octyl phosphite, bis (2,4-dicumylphenyl) pentaerythritol diphosphite and the like. Among these, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite is preferable.

The organic phosphonite compound is preferably the following general formula:
R ⁵ -P (OR ⁶ ) (OR ⁷ ) (6)
(In the formula, R ⁵ , R ⁶ and R ⁷ are each a hydrogen atom, an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 30 carbon atoms, and among R ⁵ , R ⁶ and R ⁷ , At least one of them is an aryl group having 6 to 30 carbon atoms.)
The compound represented by these is mentioned.

  Examples of the organic phosphonite compound include tetrakis (2,4-di-iso-propylphenyl) -4,4′-biphenylenediphosphonite, tetrakis (2,4-di-n-butylphenyl) -4,4′-biphenyl. Range phosphonite, tetrakis (2,4-di-tert-butylphenyl) -4,4'-biphenylene diphosphonite, tetrakis (2,4-di-tert-butylphenyl) -4,3'-biphenylene diphospho Knight, tetrakis (2,4-di-tert-butylphenyl) -3,3'-biphenylenediphosphonite, tetrakis (2,6-di-iso-propylphenyl) -4,4'-biphenylenediphosphonite, Tetrakis (2,6-di-n-butylphenyl) -4,4′-biphenylenediphosphonite, tetrakis (2, -Di-tert-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,6-di-tert-butylphenyl) -4,3'-biphenylenediphosphonite, and tetrakis (2,6- And di-tert-butylphenyl) -3,3′-biphenylenediphosphonite.

  As the sulfur stabilizer, any conventionally known sulfur atom-containing compound can be used, and among these, thioethers are preferred. Specifically, for example, didodecylthiodipropionate, ditetradecylthiodipropionate, dioctadecylthiodipropionate, pentaerythritol tetrakis (3-dodecylthiopropionate), thiobis (N-phenyl-β-naphthylamine) ), 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel dibutyldithiocarbamate, nickel isopropylxanthate, trilauryltrithiophosphite. Among these, pentaerythritol tetrakis (3-dodecylthiopropionate) is preferable.

  Examples of the phenol-based stabilizer include pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), octadecyl-3- (3,5-di-tert-butyl-4) -Hydroxyphenyl) propionate, thiodiethylenebis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), pentaerythritol tetrakis (3- (3,5-di-neopentyl-4-hydroxyphenyl) ) Propionate) and the like. Among these, pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionate is preferred.

  One type of stabilizer may be contained, or two or more types may be contained in any combination and ratio.

  The content of the stabilizer is preferably 0.001 to 1 part by mass with respect to a total of 100 parts by mass of (A) polybutylene terephthalate resin and (B) polycarbonate resin. When the content of the stabilizer is less than 0.001 part by mass, it is difficult to expect an improvement in the thermal stability and compatibility of the resin composition, and a decrease in molecular weight and a deterioration in hue during molding are likely to occur. When it exceeds, it will become excess amount and there exists a tendency for generation | occurrence | production of silver and a hue deterioration to occur further easily. The content of the stabilizer is more preferably 0.001 to 0.7 parts by mass, and still more preferably 0.005 to 0.6 parts by mass.

<Release agent>
The resin composition in the present invention preferably contains a release agent from the viewpoint of further improving the releasability from the mold. As the mold release agent, known mold release agents usually used for polybutylene terephthalate resins can be used. Among them, polyolefin compounds, fatty acids are preferred because they are difficult to bleed out and exhibit high mold release properties. One or more mold release agents selected from ester compounds are preferred.

Examples of the polyolefin compound include compounds selected from paraffin wax and polyethylene wax. Among them, polyethylene having a mass average molecular weight of 700 to 10000, more preferably 900 to 8000, from the viewpoint of good dispersion of the polyolefin compound. Wax is preferred.
Polyolefin compounds include carboxyl groups (carboxylic acid (anhydride) groups, ie, carboxylic acid groups and / or carboxylic anhydride groups; the same shall apply hereinafter), haloformyl groups, ester groups, carboxylate metal bases, hydroxyl groups. It is preferable to add a functional group having an affinity for polybutylene terephthalate, such as an alkoxyl group, an epoxy group, an amino group, or an amide group. This concentration is preferably more than 5 mgKOH / g and less than 50 mgKOH / g, more preferably 10 to 40 mgKOH / g, more preferably 15 to 30 mgKOH / g, and particularly preferably 20 to 28 mgKOH / g as the acid value of the polyolefin compound. preferable.
In addition, an oxidized polyethylene wax is preferable as the polyolefin-based compound since it has a small amount of volatile matter and at the same time has a remarkable effect of improving the releasability.
The acid value can be measured according to a potentiometric titration method (ASTM D1386) using a 0.5 mol KOH ethanol solution.

  Examples of the fatty acid ester compounds include fatty acid esters such as glycerin fatty acid esters and sorbitan fatty acid esters, and partially saponified products thereof. Among them, the fatty acid ester compounds are composed of fatty acids having 11 to 28 carbon atoms, preferably 17 to 21 carbon atoms. Preferred are mono- or di-fatty acid esters. Specific examples include glycerin monostearate, glycerin monobehenate, glycerin dibehenate, glycerin-12-hydroxy monostearate, sorbitan monobehenate, pentaerythritol monostearate, pentaerythritol distearate and the like. It is done.

  Moreover, as a silicone type compound, the compound modified | denatured from points, such as compatibility with polybutylene terephthalate type resin, is preferable. Examples of the modified silicone oil include silicone oil in which an organic group is introduced into the side chain of polysiloxane, silicone oil in which an organic group is introduced into both ends and / or one end of polysiloxane, and the like. Examples of the organic group to be introduced include an epoxy group, an amino group, a carboxyl group, a carbinol group, a methacryl group, a mercapto group, and a phenol group, and preferably an epoxy group. As the modified silicone oil, a silicone oil in which an epoxy group is introduced into the side chain of polysiloxane is particularly preferable.

  The content of the release agent is preferably 0.05 to 2 parts by mass with respect to 100 parts by mass in total of (A) polybutylene terephthalate resin and (B) polycarbonate resin. If it is less than 0.05 parts by mass, the surface appearance tends to be reduced due to defective mold release at the time of melt molding. On the other hand, if it exceeds 2 parts by mass, the kneading workability of the resin composition is reduced, and molding is also performed. The surface of the product may be cloudy. The content of the release agent is preferably 0.07 to 1.5 parts by mass, more preferably 0.1 to 1.2 parts by mass.

<Nucleating agent>
The resin composition in the present invention preferably contains a nucleating agent from the viewpoint of further improving moldability. As the nucleating agent, either an organic substance or an inorganic substance can be used. As the inorganic substance, simple substances such as talc, zinc powder, and aluminum powder, and nitrides such as aluminum nitride, titanium nitride, and boron nitride can be used alone or in admixture of two or more. Organic substances include calcium oxalate, sodium oxalate, calcium benzoate, calcium phthalate, calcium tartrate, magnesium stearate, polyacrylate, and other polymers, polyester, polyethylene, polypropylene and other polymers, and polymer cross-linking A thing etc. can be used individually or in mixture of 2 or more types. Of these, talc is particularly preferable, and the nucleating agent is particularly excellent in improving the moldability.

  The content of the nucleating agent is preferably 0.05 to 2 parts by mass with respect to 100 parts by mass in total of (A) polybutylene terephthalate resin and (B) polycarbonate resin. It is preferable to add a nucleating agent in such a range because the moldability tends to be improved. The content of the nucleating agent is preferably 0.07 to 1.5 parts by mass, more preferably 0.1 to 1 part by mass.

<Reinforcing filler>
The resin composition of the present invention may contain a reinforcing filler. The reinforcing filler has an effect of improving the mechanical properties of a resin composition obtained by blending with a resin, and a conventional inorganic filler for plastics can be used. Preferably, fibrous fillers such as glass fiber, carbon fiber, basalt fiber, wollastonite and potassium titanate fiber can be used. In addition, granular or amorphous fillers such as calcium carbonate, titanium oxide, feldspar minerals, clay, organic clay, glass beads, etc .; plate-like fillers such as talc; scale-like fillings such as glass flakes, mica and graphite A material can also be used.
Among these, glass fibers are preferably used from the viewpoint of mechanical strength, rigidity, and heat resistance.

  More preferably, the reinforcing filler is surface-treated with a surface treatment agent such as a coupling agent. The glass fiber to which the surface treatment agent is attached is preferable because it is excellent in durability, heat and humidity resistance, hydrolysis resistance, and heat shock resistance.

As the surface treatment agent, any conventionally known one can be used. Specifically, for example, silane coupling agents such as amino silane, epoxy silane, allyl silane, and vinyl silane are preferable.
Among these, aminosilane-based surface treatment agents are preferable, and specifically, for example, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and γ- (2-aminoethyl) aminopropyltrimethoxysilane are preferable. Take as an example.

Moreover, as a surface treating agent, epoxy resins, such as a novolac type, a bisphenol A type epoxy resin, etc. are mentioned preferably. Among these, novolac type epoxy resins are preferable.
The silane-based surface treatment agent and the epoxy resin may be used alone or in combination, and it is also preferable to use both in combination.

  The content of the reinforcing filler is preferably 0 to 100 parts by mass with respect to 100 parts by mass in total of (A) polybutylene terephthalate resin and (B) polycarbonate resin. When the content of the reinforcing filler exceeds 100 parts by mass, the fluidity is lowered, which is not preferable. The more preferable content of the reinforcing filler is 5 to 90 parts by mass, of which 15 to 80 parts by mass, more preferably 30 to 80 parts by mass, and particularly 40 to 70 parts by mass.

  The resin composition of the present invention may contain (A) a polybutylene terephthalate resin and (B) a thermoplastic resin other than the polycarbonate resin as long as the effects of the present invention are not impaired. Specific examples of the other thermoplastic resins include polyethylene terephthalate, polyamide, polyphenylene oxide, polystyrene resin, polyphenylene sulfide ethylene, polysulfone, polyether sulfone, polyether imide, and polyether ketone.

[Method for Producing Resin Composition]
As a manufacturing method of the resin composition of this invention, it can carry out in accordance with the conventional method of resin composition preparation. Usually, the components and various additives added as desired are mixed together and then melt-kneaded in a single-screw or twin-screw extruder. Moreover, it is also possible to prepare the resin composition of the present invention by mixing each component in advance or by mixing only a part of the components in advance and supplying them to an extruder using a feeder and melt-kneading them. Furthermore, (A) a polybutylene terephthalate-based resin or (B) a polycarbonate resin partly blended with a part of other components is melt-kneaded to prepare a masterbatch, and then the remaining other ingredients May be blended and melt-kneaded.
In addition, when using fibrous reinforcement fillers, such as glass fiber, it is also preferable to supply from the side feeder in the middle of the cylinder of an extruder.

  The heating temperature at the time of melt kneading can be appropriately selected from the range of usually 220 to 300 ° C. If the temperature is too high, decomposition gas is likely to be generated, which may cause opacity. Therefore, it is desirable to select a screw configuration in consideration of shear heat generation. In order to suppress decomposition during kneading or molding in the subsequent process, it is desirable to use an antioxidant or a heat stabilizer.

[Molded body]
The method for producing a molded body using the polybutylene terephthalate resin composition of the present invention is not particularly limited, and a molding method generally employed for the polyester resin composition can be arbitrarily adopted. For example, injection molding method, ultra-high speed injection molding method, injection compression molding method, two-color molding method, hollow molding method such as gas assist, molding method using heat insulating mold, rapid heating mold were used. Molding method, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding) molding method, extrusion molding method, sheet molding method, thermoforming method, rotational molding method, laminate molding method, press molding method, Examples thereof include a blow molding method. Of these, injection molding is preferred.

The shape, size, thickness and the like of the molded body are arbitrary, and the use thereof is particularly suitable for parts for electric and electronic equipment, parts for transportation equipment such as automobiles, parts for industrial machinery, and other parts for consumer use.
In particular, it is suitable for a housing or a pedestal part of an electronic device such as a personal computer, a server, or a sequencer, and is preferably molded by injection molding.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not construed as being limited to the following examples.
In the following Examples and Comparative Examples, the components used are as shown in Table 1 below.

(Example 1 , Reference Examples 2 to 7, Comparative Examples 1 to 14)
Each component shown in Table 1 was uniformly mixed with a tumbler mixer in the proportions (parts by mass) shown in Tables 2 to 4, and then a twin screw extruder (“TEX30α” manufactured by Nippon Steel Works, L / D = 52). ), A resin composition melt-kneaded under the conditions of a cylinder-set temperature of 260 ° C. and a screw rotation speed of 200 rpm is rapidly cooled in a water tank, pelletized using a pelletizer, and pellets of a polybutylene terephthalate resin composition Got.

(1) Measurement of impact resistance (Charpy impact strength with notch) The obtained pellet was subjected to a cylinder temperature of 250 ° C., a mold temperature of 80 ° C., and a molding cycle of 40 seconds using a “α100iA type” injection molding machine manufactured by FANUC. Under these conditions, an ISO test piece (thickness: 4.0 mm) was injection molded. In accordance with ISO 179, a notched test piece was produced from the obtained test piece, and a notched Charpy impact strength (unit: kJ / m ² ) was measured.

(2) Judgment of warpage Using the “Model SE-50D” injection molding machine manufactured by Sumitomo Heavy Industries, Ltd., cylinder temperature 250 ° C., mold temperature 80 ° C., staying in the cylinder for 20 minutes, 1 (the left figure in FIG. 1 is a perspective view seen from the outside of the rectangular parallelepiped box-shaped molded product, and the right figure in FIG. 1 is a perspective view showing a state in which the bottom face is up), A rectangular box-shaped molded product having a length of 53 mm, a width of 33 mm, a depth of 17 mm, and a wall thickness of 1.5 mm was formed. The gate is the two-point gate shown in the center of the bottom surface.

Fix the bottom of the box to the top, measure the length of the short side of the bottom along the line from the center of 1 mm from the short side of the bottom and the line from the center of 24 mm from the other short side. The internal warpage rate was evaluated according to the criteria.
Inner curvature ratio (%) = (length in the short side direction at a position 1 mm from the end of the box) / (length in the short side direction at a position 24 mm from the end of the box) × 100

Using the obtained warpage rate, the warping property was determined in the following three stages.
◎: Internal warpage rate is less than 1% ○: Internal warpage rate is 1-2%
X: The smaller the value of the internal warpage rate exceeding 2%, the better the dimensional accuracy because the amount of internal warpage of the molded product is small. Moreover, as an actual molded product, it is preferable that said determination is (double-circle) and (circle).

(3) Evaluation of releasability The obtained pellets were used with a “model SE-50D” injection molding machine manufactured by Sumitomo Heavy Industries, Ltd., cylinder temperature 250 ° C., mold temperature 80 ° C., molding cycle 23 seconds, cooling time. Under the condition of 20 seconds, the box-shaped molded product described in (2) Warpage determination was injection molded. The releasability at that time was evaluated in the following two stages.
○: The ejector pin mark remains on the molded product and the appearance is good. ×: The ejector pin mark remains on the molded product, or the ejector pin breaks through the molded product and continuous molding is impossible.
In order to obtain a molded article having a good appearance by continuous molding, it is preferable that no pin marks of the ejector remain.

(4) Evaluation of anti-tracking property (CTI) The obtained pellet was thick under the conditions of a cylinder temperature of 260 ° C. and a mold temperature of 80 ° C. using a “model NEX80-9E” injection molding machine manufactured by Nissei Plastic Industry Co., Ltd. A test piece of a disc having a thickness of 3.0 mm and a diameter of 50 mm was injection molded. Using the obtained test piece, the tracking resistance test method defined in the test method UL746A, paragraph 23 was measured in accordance with ASTM D3638.
An electrolytic solution (0.1% aqueous solution of ammonium chloride, resistivity 385 Ω · cm at 23 ° C.) is dropped from the nozzle of the device at intervals of 30 seconds, and a voltage of 600 V or less (25 V step) is applied between the platinum electrodes, and tracking is performed. The number of electrolyzed droplets until the occurrence of was measured, and the voltage at which the average value of 5 times was less than 50 droplets was determined. In addition, it means that tracking resistance is so favorable that a numerical value is high.

(5) Flame Retardancy (UL94) Test Using the obtained pellets using a “SE50D” injection molding machine manufactured by Sumitomo Heavy Industries, Ltd., with a cylinder temperature of 250 ° C. and a mold temperature of 80 ° C., a thickness of 0.75 mm A vertical burning test piece was injection molded. Using the obtained combustion test piece, flame retardancy was evaluated according to UL94 standard.

(6) Crystallization temperature Using the “PYRIS Diamond DSC” manufactured by PerkinElmer, the temperature was increased to 300 ° C. at a rate of temperature increase of 20 ° C./min. The temperature was lowered at 20 ° C./min, and the peak temperature of the exothermic peak showing crystallization derived from the polybutylene terephthalate resin was measured and used as the crystallization temperature.
The above evaluation results are shown in Tables 2 to 4 below.

  The polybutylene terephthalate resin composition of the present invention is a resin material that is excellent in impact resistance, flame retardancy, tracking resistance, and releasability, and has no problem of warping of a molded product. Therefore, the resin composition of the present invention is particularly suitable for electrical and electronic equipment parts, parts for transportation equipment such as automobiles, parts for industrial machines, and other parts for consumer use, and has very high industrial applicability. is there.

Claims (3)

(A) Polybutylene terephthalate-based resin having an intrinsic viscosity of 1.2 to 1.6 dl / g and (B) a polycarbonate resin having a viscosity average molecular weight of 25,000 to 35,000 , a total of 100 masses of (A) and (B) Part basis, containing 50-80 parts by weight of (A), 20-50 parts by weight of (B),
Furthermore, for a total of 100 parts by mass of (A) and (B),
(C) 5 to 15 parts by mass of an impact modifier containing a butadiene component, (D) 20 to 40 parts by mass of a flame retardant containing at least one selected from brominated epoxy or brominated polycarbonate, (E) 1. A polybutylene terephthalate resin composition comprising 1 to 15 parts by mass of an antimony oxide compound and 0.05 to 1 part by mass of (F) an anti-drip agent.   A casing of an electronic device obtained by injection molding the polybutylene terephthalate resin composition according to claim 1.   A pedestal part for an electronic device obtained by injection molding the polybutylene terephthalate resin composition according to claim 1.