JP7182396B2 - Flame-retardant polybutylene terephthalate resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a flame-retardant polybutylene terephthalate resin composition and a method for producing the same.

Polybutylene terephthalate resin (PBT resin) is widely used as an engineering plastic for various applications such as automobile parts and electrical/electronic equipment parts because of its excellent mechanical properties, electrical properties, heat resistance, and other various properties. Among these, materials used in electrical and electronic device parts are required to be flame retardant in order to prevent ignition due to tracking or the like. Since polybutylene terephthalate resin itself lacks flame retardancy, it is used as a flame retardant resin composition to which a flame retardant is added.

Halogenated benzyl acrylate flame retardants are one type of flame retardant added to such polybutylene terephthalate resins, and an example thereof is polypentabromobenzyl acrylate (PBBPA) as introduced in Patent Document 1. . As a method for producing this flame retardant, in paragraph [0004] of Patent Document 1, pentabromobenzyl acrylate, which is a monomer, is polymerized in ethylene glycol monomethyl ether, methyl ethyl ketone, or ethylene glycol dimethyl ether, or in chlorobenzene. A method is illustrated.

Among these, when chlorobenzene, which is a halogenated aromatic compound, is used as a solvent for polymerization, a trace amount of chlorobenzene is finally present as an impurity in PBBPA. A polybutylene terephthalate resin composition made flame-retardant by adding this also contains chlorobenzene.

Chlorobenzene is generally a stable compound, but in a high-temperature environment, when it comes into contact with metals such as metal oxides and alkali metal compounds, dechlorination occurs and compounds such as hydrogen chloride are generated. Sometimes. Therefore, when a composition containing this is used for a molded product that contacts a metal member, such as insert molding or press-fitting of a terminal, a problem of corrosion of the metal member may occur. Here, in the electric and electronic component applications described above, since a molded article made of a polybutylene terephthalate resin composition is used as an electrical insulating member in combination with a metal member that is a conductive portion, it is important that the metal member is not corroded. requested. In addition, not only when the molded product is used in combination with metal members, but also in the process of molding the molded product itself, corrosion of metal members such as screws and cylinders of molding machines and molds is suppressed. are required to do so.

By the way, polybutylene terephthalate resin alone is a resin having excellent tracking resistance. However, polybutylene terephthalate resins usually contain reinforcing fillers for adjusting various properties such as mechanical strength, various stabilizers, or various additives such as the above flame retardants. Depending on the type, the tracking resistance may be impaired. In particular, brominated flame retardants such as PBBPA are likely to cause carbonization, which can reduce tracking resistance. Therefore, in order to achieve both flame retardancy and tracking resistance, for example, Patent Document 2 discloses a thermoplastic polyester resin composition to which a phosphorus flame retardant is added instead of a brominated flame retardant. may be disadvantageous in terms of cost and leaching from the molded product. Therefore, it is required to improve the flame retardancy while ensuring the tracking resistance of the polybutylene terephthalate resin.

Japanese translation of PCT publication No. 2015-532350 International publication 2014/021101 pamphlet

An object of the present invention is to suppress deterioration of tracking resistance and corrosion of metal members in contact with the molded article in a polybutylene terephthalate resin composition using a halogenated benzyl acrylate flame retardant as a flame retardant. and

In the course of research on the above subject, the present inventor used a halogenated benzyl acrylate-based flame retardant as a flame retardant, and in a polybutylene terephthalate resin composition containing a specific tracking resistance improver, the polybutylene terephthalate resin It was found that the above problems can be solved by reducing the amount of halogenated aromatic compounds such as chlorobenzene contained in the composition, particularly by reducing the amount of halogenated aromatic compounds derived from the production process of the flame retardant. , have completed the present invention.

（式中、Ｘは、水素原子または臭素原子であり、少なくとも１つ以上のＸは臭素原子であり、ｍは１０～２０００の数である。）
（３）（Ｂ）ハロゲン化ベンジルアクリレート系難燃剤が、ポリペンタブロモベンジルアクリレートを含有する、（１）または（２）に記載の難燃性ポリブチレンテレフタレート樹脂組成物。
（４）前記難燃剤以外のハロゲン化芳香族化合物が、ハロゲン化ベンゼンを含有する、（１）から（３）のいずれかに記載の難燃性ポリブチレンテレフタレート樹脂組成物。
（５）前記難燃剤以外のハロゲン化芳香族化合物が、クロロベンゼンを含有する、（１）から（４）のいずれかに記載の難燃性ポリブチレンテレフタレート樹脂組成物。
（６）（１）から（５）のいずれかに記載の難燃性ポリブチレンテレフタレート樹脂組成物の製造方法であって、（Ｂ）ハロゲン化ベンジルアクリレート系難燃剤の製造工程を有し、該工程で用いる溶媒中のハロゲン化芳香族化合物の含有量が１０００ｐｐｍ以下であることを特徴とする、製造方法。
（７）（Ｂ）ハロゲン化ベンジルアクリレート系難燃剤の製造工程において、溶媒としてハロゲン化芳香族化合物を用いない、（６）に記載の製造方法。
（８）（Ｂ）ハロゲン化ベンジルアクリレート系難燃剤の製造工程において、溶媒としてエチレングリコールモノメチルエーテル、メチルエチルケトン、エチレングリコールジメチルエーテルおよびジオキサンからなる群から選択される一以上の溶媒を用いる、（６）又は（７）に記載の製造方法。 That is, the present invention relates to the following (1) to (8).
(1) (A) 100 parts by mass of polybutylene terephthalate resin, (B) 3 to 50 parts by mass of halogenated benzyl acrylate flame retardant, (C) olefin elastomer, acrylic core-shell elastomer, linear polyolefin resin , and 5 to 100 parts by mass of one or more tracking resistance improving resins selected from combinations thereof, and (D) talc, mica, inorganic metal compounds, and one or more tracking resistance selected from combinations thereof 0 to 100 parts by mass of a filler for improving properties; A flame-retardant polybutylene terephthalate resin composition containing 0 to 80 parts by mass of one or more nitrogen-based compounds, the flame retardant measured by headspace gas chromatography (heated at 150°C for 1 hour). A flame-retardant polybutylene terephthalate resin composition, characterized in that the content of the halogenated aromatic compound other than the above is less than 0.5 ppm.
(2) The flame-retardant polybutylene terephthalate resin composition according to (1), wherein (B) the halogenated benzyl acrylate-based flame retardant contains a brominated acrylic polymer represented by general formula (I).

(Wherein, X is a hydrogen atom or a bromine atom, at least one or more X is a bromine atom, and m is a number from 10 to 2000.)
(3) The flame-retardant polybutylene terephthalate resin composition according to (1) or (2), wherein (B) the halogenated benzyl acrylate flame retardant contains polypentabromobenzyl acrylate.
(4) The flame-retardant polybutylene terephthalate resin composition according to any one of (1) to (3), wherein the halogenated aromatic compound other than the flame retardant contains halogenated benzene.
(5) The flame-retardant polybutylene terephthalate resin composition according to any one of (1) to (4), wherein the halogenated aromatic compound other than the flame retardant contains chlorobenzene.
(6) A method for producing a flame-retardant polybutylene terephthalate resin composition according to any one of (1) to (5), comprising (B) a step of producing a halogenated benzyl acrylate flame retardant, A production method, wherein the content of the halogenated aromatic compound in the solvent used in the process is 1000 ppm or less.
(7) The production method according to (6), wherein (B) the halogenated benzyl acrylate-based flame retardant is produced without using a halogenated aromatic compound as a solvent.
(8) (B) using one or more solvents selected from the group consisting of ethylene glycol monomethyl ether, methyl ethyl ketone, ethylene glycol dimethyl ether and dioxane as a solvent in the process for producing a halogenated benzyl acrylate flame retardant; (6) or (7) The manufacturing method as described in.

According to the present invention, in a polybutylene terephthalate resin composition using a halogenated benzyl acrylate flame retardant as a flame retardant, by suppressing the amount of a halogenated aromatic compound such as chlorobenzene in the production process of the flame retardant, the poly Corrosion of metal members in contact with the butylene terephthalate resin composition can be suppressed.

An embodiment of the present invention will be described in detail below. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope that does not impair the effects of the present invention.

[Flame-retardant polybutylene terephthalate resin composition]
Details of each component of the flame-retardant polybutylene terephthalate resin composition of the present embodiment will be described below with reference to examples.

((A) polybutylene terephthalate resin)
(A) Polybutylene terephthalate resin (PBT resin) comprises at least a dicarboxylic acid component containing terephthalic acid or an ester-forming derivative thereof (C _1-6 alkyl ester, acid halide, etc.) and an alkylene having at least 4 carbon atoms. It is a polybutylene terephthalate resin obtained by polycondensation with a glycol component containing glycol (1,4-butanediol) or its ester-forming derivatives (acetylated products, etc.). In the present embodiment, (A) polybutylene terephthalate resin is not limited to homopolybutylene terephthalate resin, and may be a copolymer containing 60 mol % or more of butylene terephthalate units.

(A) The amount of terminal carboxyl groups in the polybutylene terephthalate resin is not particularly limited as long as it does not interfere with the object of the present invention, but is preferably 30 meq/kg or less, more preferably 25 meq/kg or less.

(A) The intrinsic viscosity of the polybutylene terephthalate resin is not particularly limited as long as the object of the present invention is not hindered, but it is preferably 0.60 dL/g or more and 1.2 dL/g or less, and 0.65 dL/g or more and 0.65 dL/g or more. More preferably, it is 0.9 dL/g or less. When a polybutylene terephthalate resin having an intrinsic viscosity within such a range is used, the resulting polybutylene terephthalate resin composition has particularly excellent moldability. Also, polybutylene terephthalate resins with different intrinsic viscosities can be blended to adjust the intrinsic viscosity. For example, a polybutylene terephthalate resin with an intrinsic viscosity of 0.9 dL/g is prepared by blending a polybutylene terephthalate resin with an intrinsic viscosity of 1.0 dL/g and a polybutylene terephthalate resin with an intrinsic viscosity of 0.7 dL/g. can be done. The intrinsic viscosity of polybutylene terephthalate resin can be measured, for example, in o-chlorophenol at a temperature of 35°C.

(A) In the preparation of a polybutylene terephthalate resin, when an aromatic dicarboxylic acid other than terephthalic acid or an ester-forming derivative thereof is used as a comonomer component, examples include isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4, C _8-14 aromatic dicarboxylic acids such as 4′-dicarboxydiphenyl ether; C _4-16 alkanedicarboxylic acids such as succinic acid, adipic acid, azelaic acid and sebacic acid; C _5-10 dicarboxylic acids such as cyclohexanedicarboxylic acid Cycloalkanedicarboxylic acids; ester-forming derivatives of these dicarboxylic acid components (C _1-6 alkyl ester derivatives, acid halides, etc.) can be used. These dicarboxylic acid components can be used alone or in combination of two or more.

Among these dicarboxylic acid components, C _8-12 aromatic dicarboxylic acids such as isophthalic acid and C _6-12 alkane dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid are more preferred.

(A) When a glycol component other than 1,4-butanediol is used as a comonomer component in the preparation of polybutylene terephthalate resin, examples include ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, and hexamethylene glycol. C _2-10 alkylene glycols such as , neopentyl glycol and 1,3-octanediol; polyoxyalkylene glycols such as diethylene glycol, triethylene glycol and dipropylene glycol; alicyclic glycols such as cyclohexanedimethanol and hydrogenated bisphenol A Diols; aromatic diols such as bisphenol A and 4,4'-dihydroxybiphenyl; _C2-4 alkylene oxides of bisphenol A such as ethylene oxide 2 mol adducts of bisphenol A and propylene oxide 3 mol adducts of bisphenol A adducts; or ester-forming derivatives of these glycols (acetylated products, etc.) can be used. These glycol components can be used individually or in combination of 2 or more types.

Among these glycol components, more preferred are _C2-6 alkylene glycols such as ethylene glycol and trimethylene glycol, polyoxyalkylene glycols such as diethylene glycol, and alicyclic diols such as cyclohexanedimethanol.

Comonomer components that can be used in addition to the dicarboxylic acid component and the glycol component include, for example, 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4-carboxy-4'-hydroxybiphenyl, and the like. aromatic hydroxycarboxylic acids; aliphatic hydroxycarboxylic acids such as glycolic acid and hydroxycaproic acid; _C3-12 lactones such as propiolactone, butyrolactone, valerolactone, caprolactone (ε-caprolactone, etc.); esters of these comonomer components formation derivatives (C _1-6 alkyl ester derivatives, acid halides, acetylates, etc.).

(A) The content of the polybutylene terephthalate resin is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and 30 to 70% by mass of the total mass of the resin composition. is more preferred.

式中のＸは、水素原子または臭素原子であり、少なくとも１つ以上が臭素である。Ｘの数は、一構成単位中１～５であるが、難燃化の効果から３～５であることが好ましい。平均重合度ｍは１０～２０００であり、好ましくは１５～１０００の範囲である。平均重合度が１０より低いものは、熱安定性が悪化し、２０００を超えると添加したポリブチレンテレフタレート樹脂の成形加工性を悪化させる。また、上記ブロム化アクリル重合体は１種又は２種以上混合使用してもよい。 ((B) Halogenated benzyl acrylate flame retardant)
The (B) halogenated benzyl acrylate flame retardant used in the present invention includes brominated acrylic polymers represented by the following general formula (I).

X in the formula is a hydrogen atom or a bromine atom, at least one of which is bromine. The number of X in one structural unit is 1 to 5, preferably 3 to 5 from the viewpoint of flame retardancy. The average degree of polymerization m is 10-2000, preferably 15-1000. If the average degree of polymerization is less than 10, the heat stability is deteriorated, and if it exceeds 2000, the moldability of the added polybutylene terephthalate resin is deteriorated. The brominated acrylic polymer may be used singly or in combination of two or more.

The (B) halogenated benzyl acrylate flame retardant used in the present invention contains, in addition to the above brominated acrylic polymer, which is the flame retardant itself, a solvent during polymerization and decomposition products of the brominated acrylic polymer as impurities. Although it may contain a halogenated aromatic compound derived from , particularly preferably 10 ppm or less. The content of the halogenated aromatic compound other than the flame retardant can be determined, for example, by measuring the gas generated when a sample obtained by pulverizing (B) the halogenated benzyl acrylate flame retardant is heat-treated in the headspace, using a gas chromatograph. , can be determined from the amount of gas generated from the halogenated aromatic compound.

The brominated acrylic polymer represented by general formula (I) can be obtained by polymerizing benzyl acrylate containing bromine alone, but may be obtained by copolymerizing benzyl methacrylate having a similar structure. Bromine-containing benzyl acrylates include pentabromobenzyl acrylate, tetrabromobenzyl acrylate, tribromobenzyl acrylate, or mixtures thereof. Among them, pentabromobenzyl acrylate is preferred. Benzyl methacrylate, which is a copolymerizable component, includes methacrylates corresponding to the above-described acrylates. Furthermore, copolymerization with vinyl monomers is also possible, acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate and benzyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate and benzyl methacrylate. , unsaturated carboxylic acids such as styrene, acrylonitrile, fumaric acid and maleic acid or their anhydrides, vinyl acetate and vinyl chloride. Crosslinkable vinyl monomers, xylylene diacrylate, xylylene dimethacrylate, tetrabrom xylylene diacrylate, tetrabrom xylylene dimethacrylate, butadiene, isoprene, and divinylbenzene can also be used. These are used in an equimolar amount or less, preferably 0.5 times the molar amount or less with respect to benzyl acrylate or benzyl methacrylate.

(B) As a method for producing a halogenated benzyl acrylate-based flame retardant, an example of a method for producing the above-mentioned brominated acrylic polymer is shown. A method of reacting can be mentioned. In the case of solution polymerization, the content of the halogenated aromatic compound in the solvent is preferably 1000 ppm or less, more preferably 500 ppm or less, even more preferably 300 ppm or less, and particularly preferably 100 ppm or less. preferable. It is more preferable not to use halogenated benzene or halogenated aromatic compounds such as chlorobenzene as the solvent. As the solvent for solution polymerization, aprotic solvents such as ethylene glycol monomethyl ether, methyl ethyl ketone, ethylene glycol dimethyl ether and dioxane are preferred.

(B) Halogenated benzyl acrylate-based flame retardants such as the above-mentioned brominated acrylic polymers contain water and/or alkali (earth) metal ions in order to remove reaction by-products such as residual sodium polyacrylate. Washing with the containing aqueous solution is preferred. In this specification, "containing alkali (earth) metal ions" means containing alkali metal ions and/or alkaline earth metal ions. Aqueous solutions containing alkali (earth) metal ions can be easily obtained by adding alkali (earth) metal salts to water. Certain hydroxides (such as calcium hydroxide) are most suitable. When using, for example, calcium hydroxide as the alkali (earth) metal salt, calcium hydroxide is generally soluble at about 0.126 g in 100 g of water at 20° C., and the concentration of the aqueous solution is not particularly limited as long as it is up to the solubility. . In addition, the method of washing with an aqueous solution containing water and/or alkali (earth) metal ions is not particularly limited. A method such as immersing the substrate in an aqueous solution capable of treating the substrate may be used. The brominated acrylic polymer that has been washed with an aqueous solution containing water and/or alkali (earth) metal ions generally has a dry solid content of 100 ppm or less in the hot water extract. When a brominated acrylic polymer is used, there is almost no generation of foreign matter on the surface of the molded product.

In the flame-retardant polybutylene terephthalate resin composition of the present invention, the content of the halogenated aromatic compound other than the flame retardant, which is the impurity described above, is less than 0.5 ppm, preferably 0.3 ppm or less, more preferably 0.3 ppm or less. is 0.1 ppm or less. When the content of the halogenated aromatic compound other than the flame retardant in the flame-retardant polybutylene terephthalate resin composition is within the above range, the insert-molded product using the polybutylene terephthalate resin composition has a metal terminal. Corrosion can be suppressed. The content of such a halogenated aromatic compound other than a flame retardant can be determined, for example, by measuring the gas generated when a sample obtained by pulverizing a polybutylene terephthalate resin composition is heat-treated in the head space by gas chromatography. It can be determined from the amount of gas generated from the halogenated aromatic compound.

In making the resin flame-retardant, it is preferable to use an antimony-based flame-retardant aid together. Typical flame retardant aids include antimony trioxide, antimony tetroxide, antimony pentoxide, sodium pyroantimonate and the like. Furthermore, for the purpose of preventing the spread of fire due to dripping of the burned resin, it is also preferable to use an anti-dripping agent such as polytetrafluoroethylene together.

(B) The range of addition of the halogenated benzyl acrylate flame retardant and the antimony flame retardant auxiliary to the resin is 3 to 50 parts by mass and 5 to 40 parts by mass of the polymer with respect to 100 parts by mass of the polybutylene terephthalate resin. parts, more preferably 10 to 30 parts by mass. A range of 1 to 40 parts by mass of the antimony-based flame retardant aid is preferable. If the amount of the brominated acrylic polymer and the antimony-based flame retardant aid added is too small, sufficient flame retardancy cannot be imparted, and if it is too large, the physical properties of the molded product may be deteriorated.

((C) Resin for improving tracking resistance)
To the flame-retardant polybutylene terephthalate resin composition of the present invention, (C) a resin for improving tracking resistance is supplementarily added in order to improve tracking resistance.

As the resin for improving tracking resistance (C), a resin that not only has high tracking resistance but also has a processing temperature close to that of (A) polybutylene terephthalate resin and has good compatibility can be used. Examples of such (C) resin for improving tracking resistance include olefin elastomers, acrylic core-shell elastomers, linear polyolefin resins, and combinations thereof.

Examples of olefinic elastomers include ethylene-propylene copolymers (EP copolymers), ethylene-butene copolymers, ethylene-octene copolymers, ethylene-propylene-diene copolymers (EPD copolymers), Copolymer containing at least one unit selected from ethylene-propylene-butene copolymer, ethylene-vinyl acetate copolymer, EP copolymer and EPD copolymer, olefin and (meth)acrylic monomer and copolymers (ethylene-ethyl acrylate copolymer, ethylene-glycidyl methacrylate copolymer, etc.). Preferred olefinic elastomers include EP copolymers, EPD copolymers, copolymers of olefins and (meth)acrylic monomers, with ethylene ethyl acrylate being particularly preferred. These olefinic elastomers can be used alone or in combination of two or more.

The acrylic core-shell type elastomer is a polymer in which the core layer is composed of a rubber component (soft component) and the shell layer is composed of a hard component, and acrylic rubber is used as the rubber component of the core layer. The acrylic rubber used for the core layer preferably has a glass transition temperature (Tg) of less than 0°C (eg -10°C or lower), and preferably -20°C or lower (eg -180°C or higher and -25°C or lower). is more preferable, and −30° C. or less (for example, −150° C. or more and −40° C. or less) is particularly preferable.

The acrylic rubber used as the rubber component is preferably a polymer obtained by polymerizing an acrylic monomer such as alkyl acrylate as a main component. The alkyl acrylate used as a monomer for the acrylic rubber is preferably a C1-C12 alkyl ester of acrylic acid such as butyl acrylate, more preferably a _C2 - _C6 alkyl ester of acrylic acid.

The acrylic rubber may be a homopolymer or a copolymer of acrylic monomers. When the acrylic rubber is a copolymer of acrylic monomers, it may be a copolymer of acrylic monomers or a copolymer of acrylic monomers and other unsaturated bond-containing monomers. When the acrylic rubber is a copolymer, the acrylic rubber may be obtained by copolymerizing a crosslinkable monomer.

A vinyl polymer is preferably used for the shell layer. The vinyl polymer contains at least one monomer selected from, for example, aromatic vinyl monomers, vinyl cyanide monomers, methacrylic ester monomers, and acrylic ester monomers. Obtained by polymerization or copolymerization. The core layer and shell layer of such an acrylic core-shell type elastomer may be bonded by graft copolymerization. This graft copolymerization is obtained by adding, if necessary, a graft crossing agent that reacts with the shell layer during the polymerization of the core layer to provide reactive groups to the core layer, and then forming the shell layer. When a silicone rubber is used as the graft crossing agent, an organosiloxane having a vinyl bond or an organosiloxane having a thiol is used, preferably acryloxysiloxane, methacryloxysiloxane or vinylsiloxane.

The linear polyolefin resin is preferably a polyolefin resin such as polyethylene or polypropylene that does not substantially have side chains and has a viscosity average molecular weight of 10,000 to 1,000,000 as measured by ASTM D2857 method.

(C) The amount of resin for improving tracking resistance added is 5 to 100 parts by mass, and may be 10 to 90 parts by mass or 20 to 80 parts by mass with respect to 100 parts by mass of polybutylene terephthalate resin. However, if a resin with low flame retardancy is added in a large amount, the combustibility of the composition may be deteriorated. It is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, relative to the entire resin composition.

((D) Tracking resistance improver)
In order to further improve the tracking resistance, the flame-retardant polybutylene terephthalate resin composition of the present invention is supplementarily added with (D) a tracking resistance improver.

Specific examples of the (D) tracking resistance improver include talc, mica, and inorganic metal compounds, and any one of these or a combination thereof can be used.

Known talc can be used, and preferably talc having a volume average particle size of 1 to 10 μm or compressed fine powder talc having a bulk specific gravity of 0.4 to 1.5 can be used.

Known mica can be used, and preferably mica having a volume average particle size of 10 to 60 μm can be used.

Examples of inorganic metal compounds include metal salts of inorganic acids (inorganic acids other than phosphoric acid and silicic acid, such as carbonic acid, boric acid, stannic acid, tungstic acid, sulfuric acid, etc.), metal oxides (magnesium oxide, iron oxide, oxide titanium, zinc oxide, alumina, etc.), metal hydroxides (aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, alumina hydrate (boehmite), etc.), metal sulfides (zinc sulfide, molybdenum sulfide, tungsten sulfide, etc.) etc., and preferred examples include barium sulfate, zinc sulfide, zinc borate, calcium borate, and zinc stannate.

These (D) tracking resistance improvers may be surface-treated (surface-coated) with an inorganic compound and/or an organic compound. Examples of inorganic compounds used for surface treatment include aluminum hydroxide, alumina, Preferable examples include silica, zirconia, zirconium hydroxide, zirconia hydrate, cerium oxide, cerium oxide hydrate, aluminum such as cerium hydroxide, inorganic oxides and hydroxides such as silicon, zirconium and cerium. Also, these inorganic compounds may be hydrates. Among these, aluminum hydroxide and silica are preferable, and when silica is used, a silica hydrate represented by SiO ₂ ·nH ₂ O is particularly preferable. Epoxy compounds and amine compounds are preferable as organic compounds used for surface treatment, and epoxy compounds such as bisphenol A type epoxy and novolac type epoxy, and amine compounds such as monoethanolamine, diethanolamine, triethanolamine and dichlorohexylamine. can be exemplified as a more preferable compound.

The amount of the tracking resistance improver (D) added is 0 to 100 parts by mass, and may be 0 to 90 parts by mass or 0 to 80 parts by mass, relative to 100 parts by mass of the polybutylene terephthalate resin.

((E) Nitrogen-based compound)
In order to further improve the tracking resistance of the flame-retardant polybutylene terephthalate resin composition of the present invention, (E) a nitrogen-based compound is additionally added.

(E) Nitrogen compounds include triazine compounds, benzoguanine compounds, tris(hydroxyalkyl)isocyanurate terephthalate compounds, allantoin compounds, glycoluril compounds, and combinations thereof.

Specific examples of triazine compounds include cyanuric acid, trimethylcyanurate, triethylcyanurate, tri(n-propyl)cyanurate, methylcyanurate, diethylcyanurate, isocyanuric acid, trimethylisocyanurate, triethylisocyanurate, tri(n - propyl) isocyanurate, diethyl isocyanurate, methyl isocyanurate, melamine, melamine cyanurate, melamine phosphate compounds, dimelamine phosphate compounds, melamine polyphosphate compounds, bismelamine zincophosphate, bismelamine aluminotriphosphate, melamine sulfate, ammelide , ammeline, formoguanamine, guanylmelamine, cyanomelamine, arylguanamine, melam, melem, melon and the like.

The amount of the nitrogen-based compound (E) added is 0 to 80 parts by mass, and may be 0 to 70 parts by mass or 0 to 60 parts by mass, based on 100 parts by mass of the polybutylene terephthalate resin.

(filler)
Fillers are optionally used in the compositions of the present invention. Such fillers are preferably blended in order to obtain excellent properties such as mechanical strength, heat resistance and dimensional stability, and are particularly effective for the purpose of increasing rigidity. This is a fibrous, granular or plate-like filler depending on the purpose, and a compound different from the (C) tracking resistance improver is used.

Fibrous fillers include glass fiber with circular cross section, glass fiber with flat cross section, asbestos fiber, carbon fiber, silica fiber, silica/alumina fiber, zirconia fiber, potassium titanate fiber, stainless steel, aluminum, titanium, copper, brass, etc. metal fibrous materials such as High-melting organic fibrous substances such as fluororesins and acrylic resins can also be used.

Examples of powdery fillers include glass beads, glass powder, quartz powder, kaolin, clay, diatomaceous earth, wollastonite, silicon carbide, silicon nitride and various metal powders.

Moreover, glass flakes, various metal foils, etc. are mentioned as a plate-shaped inorganic filler.

The type of filler is not particularly limited, and one or more fillers can be added. In particular, circular cross-section glass fibers, flat cross-section glass fibers, potassium titanate fibers, and wollastonite are preferably used.

Although the amount of the filler to be added is not particularly specified, it is preferably 200 parts by mass or less with respect to 100 parts by mass of the polybutylene terephthalate resin. When the filler is excessively added, the formability is poor and the toughness is lowered.

(Additive)
Further, to the composition of the present invention, known substances that are generally added to thermoplastic resins and the like can be added and used together in order to impart various desired properties according to the purpose. For example, antioxidants, ultraviolet absorbers, stabilizers such as light stabilizers, antistatic agents, lubricants, release agents, colorants such as dyes and pigments, plasticizers, fluidity improvers, toughness improvers, hydrolysis resistance Any of flame retardants other than flame retardants, halogenated benzyl acrylate-based flame retardants, and resins other than resins for improving tracking resistance can be added.

In addition, when the composition of the present invention is used in a colored form, particularly in the case of dark coloration, from the viewpoint of designability and the like, black or dark colorant, not carbon black, is used as the colorant from the viewpoint of tracking resistance. It is desirable to add organic dyes or organic pigments.

In addition, when adding a phosphorus-based flame retardant as a flame retardant other than the halogenated benzyl acrylate-based flame retardant, organic phosphinate metal salt, organic diphosphinate metal salt, condensed phosphate (resorcinol phosphates, hydroquinone phosphates, biphenol phosphates, etc.), phosphazene compounds (cyclic phenoxyphosphazene, chain phenoxyphosphazene, crosslinked phenoxyphosphazene, etc.) can be used. , aluminum methylethylphosphinate, and zinc diethylphosphinate. In addition, when adding a halogen-based flame retardant as a flame retardant other than a halogenated benzyl acrylate-based flame retardant, a halogenated epoxy-based flame retardant, a halogenated phenoxy-based flame retardant, a halogenated polyphenylene ether-based flame retardant, a halogenated styrene-based Halogenated flame retardants such as flame retardants, halogenated phthalimide flame retardants, and halogenated polycarbonate flame retardants can be mentioned. , free chlorine, and free sulfur are each preferably 0.5% by mass or less.

[Method for producing flame-retardant polybutylene terephthalate resin composition]
The flame-retardant polybutylene terephthalate resin composition of the present invention may be in the form of a powder mixture or a molten mixture (melt-kneaded product) such as pellets. A method for producing a polybutylene terephthalate resin composition according to one embodiment of the present invention includes (B) a step for producing a halogenated benzyl acrylate flame retardant. Since the steps are as described above, the description is omitted here.
The method for producing the polybutylene terephthalate resin composition is not particularly limited, and it can be produced using equipment and methods known in the art. For example, the necessary ingredients can be mixed and kneaded using a single-screw or twin-screw extruder or other melt-kneading equipment to prepare pellets for molding. Multiple extruders or other melt-kneading devices may be used. Also, all the components may be fed from the hopper at the same time, or some of the components may be fed from the side feed port.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In addition, the characteristic evaluation was performed by the following method.

(1) Content of Halogenated Aromatic Compound A material obtained by dry blending the components and compositions (parts by mass) shown in Table 1 was supplied to a twin-screw extruder (manufactured by Japan Steel Works, Ltd.) having a screw of 30 mmφ. A sample was prepared by pulverizing pellets of the polybutylene terephthalate resin composition obtained by melt-kneading at 260°C. Take 5 g of the sample and leave it at 150° C. for 1 hour in a 20 ml head space, then use an apparatus: Yokogawa Hewlett-Packard HP5890A, column: HR-1701 (0.32 mm diameter×30 m) at 50° C. After holding for 1 minute, the temperature was raised at 5°C/min, and the amount of gas generated from the halogenated aromatic compound was measured by gas chromatography, and the content of the halogenated aromatic compound was indicated in ppm. Table 1 shows the results.

(2) Metal corrosiveness A material dry blended with the components and compositions (mass parts) shown in Table 1 is supplied to a twin-screw extruder (manufactured by Japan Steel Works, Ltd.) having a screw of 30 mmφ and melted at 260 ° C. 50 g of pellets of the polybutylene terephthalate resin composition obtained by kneading were placed in a 300 ml glass stoppered bottle together with a silver plate of 1 cm×1 cm, and the bottle was stoppered and allowed to stand in a gear oven at 150° C. for 500 hours. After that, the surface of the silver plate was visually observed, and evaluated as ◯ when no corrosion occurred, and as x when corrosion occurred. Table 1 shows the results.

(3) Flame retardancy A dry blended material with the components and compositions (mass parts) shown in Table 1 is supplied to a twin-screw extruder (manufactured by Japan Steel Works, Ltd.) having a screw of 30 mmφ and melted at 260 ° C. The pellets of the polybutylene terephthalate resin composition obtained by kneading were dried at 140° C. for 3 hours, and then injection molded at a cylinder temperature of 250° C. and a mold temperature of 70° C., conforming to UL94 and having a thickness of 1. /32 inch test pieces were prepared to evaluate flammability. Table 1 shows the results.

(4) Tracking resistance A dry-blended material with the components and compositions (mass parts) shown in Table 1 is supplied to a twin-screw extruder (manufactured by Japan Steel Works, Ltd.) having a screw of 30 mmφ and melted at 260 ° C. The polybutylene terephthalate resin composition obtained by kneading was evaluated for PLC (Performance Level Category) grade of comparative tracking index (CTI) in accordance with UL746A. When the PLC grade was the highest rank of "0", it was evaluated as "O", and otherwise as "X". Table 1 shows the results.

表中のＮ．Ｄ．は検出限界（０．１ｐｐｍ）以下であることを示す。
含有量の単位は、質量部である。

N.C. in the table. D. indicates that it is below the detection limit (0.1 ppm).
The unit of content is parts by mass.

The details of each component listed in Table 1 are as follows.
(A) PBT resin: manufactured by Wintech Polymer Co., Ltd., polybutylene terephthalate resin having a terminal carboxyl group concentration of 20 meq/kg and an intrinsic viscosity of 0.7 dL/g (B-1) PBBPA1: using ethylene glycol monomethyl ether as a solvent Polymerized polypentabromobenzyl acrylate (8 ppm halogenated aromatic compound content other than flame retardants)
(B-2) PBBPA2: Polypentabromobenzyl acrylate polymerized using chlorobenzene as a solvent (halogenated aromatic compound content other than flame retardant: 150 ppm)
(C-1) Resin for improving tracking resistance 1: Acrylic core-shell type elastomer having a core layer of acrylic rubber and a shell layer of vinyl polymer (Rohm and Haas Japan Co., Ltd., Paraloid EXL2314)
(C-2) Tracking resistance improving resin 2: Ethylene-glycidyl methacrylate copolymer (olefin-based elastomer, manufactured by Sumitomo Chemical Co., Ltd., BONDFAST 7M)
(D) Talc: Crown talc PP manufactured by Matsumura Sangyo Co., Ltd.
(E) nitrogen-based compound: melamine cyanurate (manufactured by BASF, Melapur MC50)
Glass fiber: ECS03T-127 manufactured by Nippon Electric Glass Co., Ltd. (circular cross-section glass fiber with an average fiber diameter of 13 μm and an average fiber length of 3 mm)
Antimony trioxide: PATOX-M manufactured by Nihon Seiko Co., Ltd.
Anti-drip agent: Polytetrafluoroethylene

Claims (8)

(A) 100 parts by mass of polybutylene terephthalate resin;
(B) 3 to 50 parts by mass of a flame retardant comprising a halogenated benzyl acrylate flame retardant;
(C) 5 to 100 parts by mass of one or more resins for improving tracking resistance selected from olefinic elastomers, acrylic core-shell elastomers, linear polyolefin resins, and combinations thereof;
(D) 0 to 100 parts by mass of one or more fillers for improving tracking resistance (excluding talc) selected from mica , inorganic metal compounds, and combinations thereof;
(E) 0 to 80 parts by mass of one or more nitrogen-based compounds selected from triazine compounds, benzoguanine compounds, tris(hydroxyalkyl)isocyanurate terephthalate compounds, allantoin compounds, glycoluril compounds, and combinations thereof A flame-retardant polybutylene terephthalate resin composition containing
A flame-retardant polybutylene terephthalate, characterized in that the content of a halogenated aromatic compound other than the flame retardant is less than 0.5 ppm, as measured by headspace gas chromatography (heating at 150°C for 1 hour). Resin composition. 2. The flame-retardant polybutylene terephthalate resin composition according to claim 1, wherein (B) the halogenated benzyl acrylate-based flame retardant contains a brominated acrylic polymer represented by general formula (I).

(Wherein, X is a hydrogen atom or a bromine atom, at least one or more X is a bromine atom, and m is a number from 10 to 2000.) 3. The flame-retardant polybutylene terephthalate resin composition according to claim 1, wherein (B) the halogenated benzyl acrylate flame retardant contains polypentabromobenzyl acrylate. The flame-retardant polybutylene terephthalate resin composition according to any one of claims 1 to 3, wherein the halogenated aromatic compound other than the flame retardant contains halogenated benzene. The flame-retardant polybutylene terephthalate resin composition according to any one of claims 1 to 4, wherein the halogenated aromatic compound other than the flame retardant contains chlorobenzene. A method for producing the flame-retardant polybutylene terephthalate resin composition according to any one of claims 1 to 5,
(B) A production method comprising a step of producing a halogenated benzyl acrylate flame retardant, wherein the content of the halogenated aromatic compound in the solvent used in the step is 1000 ppm or less. (B) The production method according to claim 6, wherein no halogenated aromatic compound is used as a solvent in the production step of the halogenated benzyl acrylate flame retardant. (B) The process for producing a halogenated benzyl acrylate flame retardant, according to claim 6 or 7, wherein one or more solvents selected from the group consisting of ethylene glycol monomethyl ether, methyl ethyl ketone, ethylene glycol dimethyl ether and dioxane are used as solvents. manufacturing method.