CA1333509C - Flame-retardant polybutylene terephthalate resin composition and molded article for electrical component - Google Patents

Abstract

A resin composition comprises a polybutylene terephthalate, a halogenated bisimide having the formula (1) and a polytetrafluoroethylene resin and is improved in flame retardancy and at the same time moulding properties. It is useful for parts of electric instruments.

Description

1333~09 FLAME-RETARDANT POLYBUTYLENE TEREPHTE~ALATE
RESIN COMPOSITION AND MOLDED ARTICLE FOR
ELECTRICAL COMPONENT

The invention relates to a polybutylene tere-phthalate composition which is provided with excellent flame retardancy and well-balanced performance and ls improved in the moldability (e . g., flow mold- ng cycle, prevention of mold staining, etc. ) and the prevention of staining of metals when used for electrical components etc.
[Prior Art ]
Polybutylene terephthalate and a copolymer composed of at least 80 % by weight of polybutylene terephthalate (hereinafter generically referred to as "PBT") have been used as engineering plastics for widespread applications, such as automobiles and electrical and electronic equipment, because they are crystalline thermoplastic resins which are excellent in mechanical and electrical properties as well as in physical and chemical characteristics.
PBT resin compositions compounded with organo-halogen flame retardants or flame-retardant assistants further added thereto for the purpose of imparting flame retardancy thereto have hitherto --I

1333~
been used for applications where flame retardancy is required, such as electrical components.
However, known PsT resin compositions compounded with flame retardants and flame-retardant assistants have the following problems.
~ 1) The presence of a flame retardant and an assistant used therewith brings about a lowering in the physical properties of molded articles.

(2) PBT is decomposed and deteriorate during , the preparation of a composition or molding by the action of a flame retardant and an assistant used therewith of interaction thereof.

(3) A flame retardant and an assistant used therewith or by-products of the decomposition thereof bring about corrosion and staining of a mold, so that the dimensional accuracy of a molded article and fabrication efficiency are lowered.

(4) A flame retardant and an assistant used therewith or by-products of the decomposition thereof bring about the formation of spots on a molded article which spoils the appearance and performance of the molded article.
(S) Poor compatibility of a flame retardant with the resin brings about oozing of the flame retardant on the surface of a molded article to -z -1333~0-9 cause various problems.
(6) The flow of the resin is kindered, so that it becomes difficult to conduct molding.
(7) When a molded article is used, a flame retardant and an assistant used therewith or by-products of the decomposition thereof corrode or stain a metal in contact therewith or present in the vicinity thereof, which hinders the functions of electrical _ ~nf~r~tS. For example, when a molded article is used in electrical components having electric contacts made of a metal ~e . g ., housings or boards of switches, relays, etc.), there occurs various problems including a remarkable increase in the electrical resistance of the contact resulting from the staining of the contact metal during the long-term use thereof.
Various proposals have been made in order to solve these problems. ~owever, it was very difficult to prepare a flame-retardant PsT
composition capable of solving all of the above-described problems even though it was possible to solve part of the problems. Therefore, the development of a flame-retardant PsT composition capable of solving all of the above-described pr~ has eagerLy been rlesired.

1333~03 72049-5 In general, the molding of polybutylene terephthalate is relatively easy as compared with that of polyethylene terephthalate. However, in recent years, there are many cases where a further reduction in the production cost of molded articles is desired. In particular, there is an increasing demand for the enhancement of productivity through shortening of the molding cycle (i.e., the so-called high-cycle molding).
[Summary of the Invention]
The present inventors have made extensive and intensive studies with a view to developing a f lame-retardant PBT
composition which has excellent flame retardancy and well-balanced performance free from the above-described drawbacks and particularly enables the shortening of the molding cycle and the reali~ation of the high-cycle molding and causes no problem of the staining of metal, which has led to the completion of the present invention.
Specifically, the present invention relates to a flame-retardant polybutylene terephthalate resin composition comprising, based upon the total weight of the composition: (A) a poly-butylene terephthalate base resin; (B) 0.5 to 25% by weight of a halogenated bisimide represented by the general formula:

O O
~I 11 R N--R --N R
2\ / 1 \ / 3 C C
Il 11 O O

1333~09 wherein Rl is a divalent organic group and R2 and R3 are each a divalent organic group, provided that at least one of R2 and R3 has at least one halogen atom; (C) 0 . 05 to 5% by weight of a polytetrafluoroethylene resin; (D) 0 to 60% by weight of an organic filler; and (E) 0.05 to 5% by weight of a low molecular weight polyethylene.
In addition, the present invention provides a PBT
composition having desired performance and effects further improved by incorporating an olefinic polymer (E) and/or a stabili~er (F) to the above-mentioned fundamental components.
The components constituting the composition of the present invention will now be described in more detail.
First of all, the PsT resin to be used as component (A) in the present invention is polybutylene terephthalate prepared by polycondensation of 1, 4-butanediol with terephthalic acid or a lower alcohol 1333~
ester thereof and may be a copolymer composed of 80 ~ by weight of polybutylene terephthalate.
Examples of the c ~ r include aliphatic and aromatic polybasic acids, such as isophthalic acid, naphthalenedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid and succinic acid, or ester forming derivatives thereof; lower alkylene glycols such as 1, 3-propanediol, 1,6-h~ n~1;sl~ and 1,8-octanediol; aromatic alcohols such as bisphenol A and 4, 4 ' -dihydroxy-biphenyl: an adduct of an alcohol with an alkylene oxide, such as an adduct of bisphenol A with 2 mol of propylene oxide; and polyhydroxy compounds, such as glycerin and pentaerythritol, or ester forming derivatives thereof.
Polybutylene terephthalate is particularly pre f erable .
In the present invention, the halogenated bisimide as component (B) to be compounded with the PBT resin as component (A) is a compound represented by the following general formula (1):

O O
Il 11 R 2` ~ \ N--R,--N ~ ,` R 3 Il 11 O O

133330~

Rl ls a d$valent organlc group such as an alkylene.
preferably havlng 1 to 25 carbon atoms, and an arylene, preferably havlng 6 to 20 carbon atoms. More preferable ls an alkylene havlng 1 to 6 carbon atoms. Examples thereof lnclude methylene, ethylene, 1,4-butylene, 1,6-hexamethylene, phenylene, 4,4'-methylenedlphenylene, 4,4'-oxydlphenylene, xylylene, tetra-chloroxylylene, and tetrabromoxylylene. Among them, ethylene, butylene, and hexamethylene are preferable. At least one, pre-ferably both of R2 and R3 are a dlvalent organlc group havlng at 10 least one halogen atom, preferably a dlvalent halogenated aromatlc group and generally a dlvalent phenylene group havlng 1 to 4 halo-gen atoms. The halogen ls preferably bromo, partlcularly prefer-ably 4-bromophenylene group.
Zxamples of the blslmlde represented by the formula ( l ) as component (B) lnclude the followlng compounds:
N,N'-(p- and m-phenylene)-bls[3,4,5,6-tetrachloro-phthallmlde], N,N'-(p- and m-phenylene)-bls[3,4,5,6-tetrabromo-phthallmlde], N,N'-(methylenedl-p-phenylene)-bls[3,4,5,6-tetra-chlorophthallmlde], N,N'-(methylenedl-p-phenylene)-bls[3,4,5,6-20 tetrabromophthallmlde], N,N'-oxy-dl-p-phenylene)-bls[3,4,5,6-tetrachlorophthallmlde], N,N'-(oxy-dl-p-1333~09 phenylene)-bis[3,4,5,6-tetrabromophthalimide], N,N'-(p- and m-phenylene) -bischloroendoimide, *N,N'- (p-and m-tetrachloroxylylene) -bis [ 3, 4, S, 6-tetrachloro-phthalimide], *N,N'-(p- and m-tetrachloroxylylene)-bis[3,4,5,6-tetrabromophthA1im;~], *N,N'-(p- and m-tetrachloroxylylene)-bischloroendoimide, N,N'-(1, 2-ethylene) -bischloroendoimide, ~,N' - (1, 2-ethylene) -bis [3, 4, 5, 6-tetrabromophthalimide], N,N'-bis(1,2,3,4,5-pentabL~ -hpn7yl)~yL~ ll;timide~
and N,N ' -bis (2, 4, 6-tribromophenyl) pyrome1litimide .
With respect to the compounds mar ;ed with *, the tetrahaloxylene group is 1, 2, 4, 5-tetrahaloxylylene or 1, 3, 4, 5-tetrahaloxylylene.
Among them, a lower alkylenebistetrabromophthalimide is preferable, and N,N'-ethylenebistetrabromophthalimide is particularly preferable.
The content of _ , ~n~nt (B) is 0 . 5 to 25 %
by weight, preferably 1 to 15 % by weight based on the total amount of the composition. When the content is too large, mechanical and physical properties, thermal stability, etc. are lowered, so that the appearance of the resin is spoiled. On the other hand, when it is too small, not only the flame retardancy becomes unsatisfactory but also no sufficient effect can be attained with respect to the 1333~09 high cycle moldability derived from the synergistic effect attained by a combination with the other, , -nf~nt (s) .
In the present invention, ti is preferred to use component (B) in combination with a flame-retardant assistant.
Examples of the flame-retardant assistant include metallic oxides and hydroxides such as antimony triodixe, antimony halide, aluminum hydroxide, and magnesium hydroxide . The f lame-retardant assistant is added in an amount of O to 15 % by weight, preferably 1 to 10 9~ by weight based on the total amount of the composition.
The polytetraf luoroethylene resin as component (C) to be used in the present invention can be prepared by known processes and is easily commercially available. In general, this resin is a white solid prepared by polymerization of tetraf luoroethylene in an aqueous medium in the presence of a radical catalyst. Polytetrafluoroethylene as component (C) may be one having any degree of polymerization (viscosity) selected according to fabricability, dispersibility, and other physical properties of the composition. The particle diameter as well is widely ad justable from O . 05 llm 1333~0~
to several millimeters. Further, it is also possible to use polytetrafluoroethylene having any shape from granule to fiber. With respect to the above-described shape and particle diameter, suitable shape and size may be experimentally selected f~ep~n~l;n~ upon the fabricability and the intended property and effect of the composition. The amount of incorporation of ~ n~nt (C) is O . 05 to 5 % by weight, preferably O . OS to 3 % by weight based on the total amount of the composition. When the amount of component (C) is too small, the flame retardancy becomes unsatisfactory in connection with other components, and in particular no suf f icient improvement can be attained in the dripping as determined by the combustion test according to U~--94, while when it is too large, the physical properties are unfavorably lowered due to poor dispersion.
The feature of the present invention resides in a synergistic effect attained by a combination of the following three c~ n~nts~ i.e., (A) PBT, (B) halogenated bisimide, and (C) tetrafluoroethylene.
The ef fect of the present invention cannot be attaiend when any one of the above-described three components is absent F replaced by other substance.

13335~
That is, a combined use of a flame retardànt as c ,-~n,~nt (B) and polytetrafluoroethylene as ~ I~^n~nt (C) according to the present invention brings about the formation of a composition having various advantages such as an ability to impart excellent flame retardancy to crystalline PBT, freedom from dripping, excellent dispersion among the three ~ ts, freedom from the occurrence of spots on the surface of a molded article as opposed to other flame-retardant compositions liable to bring about such unfavorable phf~n, ~n;l, excellent mechanical properties, freedom from the occurrence of separation and deposition of each ~ nf-~t during fabricaiton or use at a high temperature, and freedom from corrosion of metal by virtue of excellent stability because of little or no occurrence of decomposition and deterioration of each component.
The flame-retardant PBT composition comprising CO. o~ntS (A), (B), and (C) has advantages such as an effect of increasing the rate of solidification of the PBT resin through the rise of the crystalliza-tion temperature and acceleration of crystallization during solidification by virtue of the coexistence of components (B) and (C), excellent flow, little or no 1333~

occurrence of deposltlon and corroslon on a mold, and an effect of enabllng hlgh cycle moldlng through great contrlbution to shorten-lng of the moldlng cycle. The above-descrlbed advantages can be attalned by synerglsm of components (A), (~), and (C) accordlng to the present lnventlon. Therefore, for example, a polyester elast-omer whereln a large amount of polyoxyalkylene glycol ls used as a monomer cannot exhlblt any effect of shortenlng the moldlng cycle even when the same polyester ls used as component (A).
~ext, wlth respect to the lnorganlc f lller as component 10 (D), lt ls preferable to lncorporate thls component for the purpose of preparlng a molded artlcle havlng excellent performance wlth respect to mechanlcal strengths, heat reslstance, dlmenslonal stablllty (reslstance to deformatlon and warplng) and electrlcal propertles, and flbrous, granulated and flaky flllers may be used dependlng upon the lntended purposes.
Examples of the flbrous flller lnclude lnorganlc flbrous materlals, e.g., glass flber, carbon flber, slllca flber, slllca-alumlna flber, ~lrconla flber, boron nltrlde flber, slllcon nltrlde flber, boron flber, potasslum tltanate flber, and flbrous 20 materlals )( 12 1333~0~
of metals such as stainless steel, aluminum, titanium, copper, and brass. Representative examples of the fibrous filler include a glass fiber and a earbon fiber. It is also possible to sue high-melting organic fibrous materials sueh as polyamide and acrylic resin.
Examples of the pa-ticulate filler include carbon blaek, silica, ground quartz, glass bead, glass powder, silicates such as calcium sllicate, aluminum silieate, kaolin, talc, clay, diatomaceous earth and wollastonite, metallic oxides such as iron oxide, titanium oxide, zinc oxide and alumina, metal earbonates sueh as ealeium earbonate and magnesium earbonate, metal sulfates such as calcium sulfate and barium sulfate, and other fillers such as silieon earbide, silieon nitride, boron nitride and various metallic powders.
Examples of the flaky inorganic material inelude miea, glass flake, and various metallic foi15 .
The above-described inorganic fillers can be usec ~,c,r.c OL- in a combination of two or more of them. A combined use of a flbrous filler, particularly a glass fiber, with a granular and/or flaky filler is preferable for attaining a combina-. :~

1333~

tlon of mechanlcal strengths wlth dlmenslonal accuracy, electrlcal propertles, etc.
If necessary, lt ls preferable to use the above-descrlbed flllers ln comblnatlon wlth a slzlng agent or a surface treatment. ~xamples of the compound used for thls purpose lnclude functlonal compounds such as epoxy compounds, lsocyanate com-pounds, sllane compounds, and tltanate compounds. These compounds may be used by prevlously conductlng surface treatment or slzlng treatment. Alternatlvely, they may be added together wlth other 10 components when the components are mlxed wlth each other.
In the present lnventlon, the amount of lncorporatlon of the above-descrlbed lnorganlc f lller ls 0 to 60 % by welght, pre-ferably S to 50 % by welght based on the total amount of the composltlon. When thls amount exceeds 60 % by welght, not only lt becomes dlfflcult to conduct fabrlcatlon but also there occurs a problem wlth respect to the mechanlcal st rengths of a molded artlcle. The amount of the functlonal surface treatment used ln comblnatlon wlth the lnorganlc flller ls 0 to 10 % by welght, preferably 0 . 05 to 5 % by welght .
Even when the composltlon of the present lnventlon ls used as lt ls, lt has mechanlcal propertles and thermal stablllty superlor to those of known f lame retardant-contalnlng PBT compo-sltlons and lt can exert a remarkable effect on the moldlng cycle 1333~09 and the preventlon of stalnlng of metal. However, a further lmproved effect can be attalned when the above-descrlbed compo-nents ~A) and (D) are used ln comblnatlon wlth an oleflnlc polymer as component (E) and/or an amlne or amlde stablllzer as component (F) .
The term "oleflnlc polymer" as component (E) used hereln ls lntended to mean any polymer or copolymer malnly composed of constltuent unlts comprislng an olefln, and examples thereof ln-clude polyethylene, polypropylene and modlflcatlons thereof and 10 copolymers, such as ethylene/propylene, ethylene/vlnyl acetate, ethylene/acryllc ester and ethylene/acryllc acld copolymers, and modlflcatlons thereof. In partlcular, lt ls preferable from the vlewpolnt of attalnlng the purpose of the present lnvent lon that these oleflnlc polymers have low molecular welghts. Further, lt ls more preferable that they be waxy whlch are poor ln ltself ln the moldablllty. The amount of lncorporatlon of the oleflnlc polymer ls 0.05 to 5 % by welght, preferably 0.1 to 3 % by welght based on the )( 13335~9 compos ition .
When the above-described olefinic pol~mer is used in combination with a particular f lame retardant as component (B) and polytetrafluoroethylene as component (C), it promotes the dispersion of these components, prevents components (B) and (C) rrom deDositing and adherins oll the surr2ce of metal suc~ as a mold during molding or standing at a hish temperature, exhibits a mold releasing action on the composition of the present invention remarkably suFe--or to that attained b~ other releas~n~ a~ents generally known to the art, and shortens the molding cycle, so that it becomes possible to conduct further improved high cycle moldinq.
The amine or amide stabilizer as component (F) is an amine or an amide compound having an aromatic group and preferably a phenylamine, an amine or amide compound having, in its molecule, an amido or sterically kindering phenolic group. E.camples of component (F) include N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydro cyhydrocinnamide), N, N ' -bis [ 3-( 3, 5-di-tert-butyl-4-hydroxyphen~l) propionyl] hydrazine, N-phenyl-N ' -isopropyl-p-phenylenediamine, N, N ' -diphenyl-p-phenylenediamine, 4, 4 ' -bis ( 4-c~ dimethyl-benzyl) diphenylamine, N-phenylnapththylamine, and 1 333~ 09 N,~'-di-3-naphthylphenyl~n~ mine. They may be used alone or in a combination of two or more of them. Among them, N,N'-hexamethylenebis (3, S-di-tert-butyl-4-hydroxyhydrocinnamide), N, N ' -bis [ 3- ( 3, S-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine, and 4, 4 ' -bis ( 4-~, cL-dimethylbenzyl ) diphenylamine are particularly pr~ferable.
In the present invention, th.~se amine or amide stabilizers are used in an amount of O . 01 to 5 % by weight, preferably O . 05 to 2 % by weight ha~ed on th.e ~omposition an.d ~ff~ctl~e in impro in~
not only the thermal stability of the composition but also the prevention of staining of a metal.
These amine or amide stabilizers suppress the decomposition of the composition of the present invention, particularly components (B) and (C) per se and has a synergistic effect of suppressing the decomposition of PBT by component (B), which not only contributes to an improvement in the molding efficiency through prevention of the corrosion and staining of the mold during molding but also prevents the corrosion and staining of metal in contact with the molded article of electrical components etc. wherein the molded article is used at a high temperature.

~_ -- 13333~9 72049-5 The composltlon of the present lnventlon may further contaln a small amount of thermoplastlc resln(s) as an auxlllary addltlve. For example, lt ls also posslble to lncorporate the followlng thermoplastlc reslns ln any proportlon accordlng to the lntended purpose: ethylene-acryllc ester copolymer, polyamlde, polyacetal, polystyrene, styrene-butadlene copolymer, styrene-butadlene-acrylonltrlle copolymer, styrene-butadlene-acryllc acld (or an ester thereof ) copolymer, styrene-acrylonltrlle copolymer, polycarbonate, polyurethane, polyphenylene oxlde, polyphenylene 10 sulflde, polybutadlene, halogenated polyolefln, polyvlnyl hallde, butyl rubber, and multllayer graft copolymer malnly composed of polyacrylate .
It ls a matter of course that ln order to lmpart a deslred property to the composltlon of the present lnventlon accordlng to the lntended purpose, the composltlon of the present lnventlon may be compounded wlth addltlves known to the art, e.g., addltlves other than the above-descrlbed components, such as lubrlcants, nucleatlng agents, mold releaslng agent, antlstatlc agents, surfactants, plastlclzers, colorants, thermal stablllzers, 20 and ultravlolet stablllzers.

X

1333~09 The composition of the present invention can be prepared by making use of known equipment and processes commonly employed in the preparation of the conven-tional resin comDosition. E~amples of the process include (i) one which comprises mixing the individual components, milling anc e~trudinc the mixture with an e:ctruder to prepare pellets, and then conducting molding; (ii) one which comprises preparing pellets each different in the composition, mi:~ing them in predet~rmi nf~ amounts and molding the mixture to prepare a predetermined molded article; and (iii) one in which a molding machine is directly charged with at least one of the components. Further, in order to attain homogeneous compounding of the components, it is preferable to employ a process which comprises pulverizing part of the resin components into f ine powders and mixing them with the other components.
The flame-retardant PBT resin composition of the present invention is molded into various molded articles which are required to have flame retardancy, and are very useful when used in electrical components, particularly electrical and electronic parts having an electric contact made of metal, such as switches and relays.

_\q_ 1333~09 The PBT composition of the invention has well-bAl Anc~d functions by virtue of an effective improvement in the following characteristics.
(1) Since the composition brings about no deposition on the surface of a mold during molding and has excellent thermal stability, not only the mold is less susceptible to corrosion by a df~r~ , osition product or the like but also fabrica-tion efficiency can be improved.
(2) The molded article is less susceptible to thermal deterioration.
(3) There occurs no spots having different colors on the molded article.
(4) The composition is excellent in the flame retardancy, and oozing of the flame retardant hardly occurs during use thereof.
(5) The composition is excellent in the mechanical properties such as tensile characteristics and Izod impact strength.

(6) The composition exhibits excellent flow and high rate of solidification and can shorten the molding cycle, so that it becomes possible to realize -~0~
:

1333~
high cycle molding.

(7) The corrosion or staining of a coexisting metal (contact) during use of the composition can be effectively prevented.
[ Example ]

In the E.~am21es, the evaluation of the characteristics ~ere conducted ~,y the follo~ing methods .
(1) ~easurement of physical properties:
tensile test: accordlng to AST~ D 638 Izod impact strenqth: according to AST!~ D 256 (2) Residence test (thermal stability):
A sample was allowed to stay within a cylinder of a molding machine at a cylinder temperature of 260C for 30 min and then molded into a specimen.
The molded specimen was subjected to a tensile strength test to evaluate the thermal stability and deterioration of the sample.
( 3 ) Combustion test ( UL- 9 4 ):
Tests on the flame retardancy and the dripping of the resin durinq combustion were conducted by making use of five specimens (thickness: 1/32 in.) according to the Sub ject 96 (tlL9~) of ~nderwriters ' Laboratories .
easurement of flo~:
2 ) 1333.~09 Molding was conducted under the following conditions by making use of a test mold for measurement of rod flow length (cavity: 20 mm in width x 2.0 mm in thickness), and the flow was evaluated based on the flow length (the length of the molded artiele):
molding eonditions: eylinder temperature: 250C
injeetion pressure: 1,000 kg/em2 - mold temperature: 60C
(5) Critieal molding cycle:
A molded article having a cylindrical bottom (outer diameter: 40 mm~; height: 40 mm; average thickness: 5 mm) was molded under the following conditions to determine the critical time (sec) for molding eyele eapable of providing a molded article having an exeellent appearance. The smaller the numerical value, the better the high eyele moldability.
Molding eonditions: eylinder temperature: 250C
injection pressure: 1,400 kg/cm2 mo ld tempe rature: 9 0 C
molding cycle: injection-holding time was kept constant to determine cooling time.
(6) Visual inspection of molded article:

., ~33~o9 A disk (100 mm~; thickness: 3 mm) was molded and observed with the naked eye with respect to the occurrence and the number of spots having different colors and oozing after being left to stand at 120C for 72 hr. Evaluation was made based on the following criteria:
O.... free spot ( ~....small number of spots X....many spots -r . . f ree oozing ~ ~.... small degree of oozing ~ X....large degree of oozing ~ .
(7) Evaluation of staining of metal:
A sample (pellet) was sufficiently dried.
Thereafter, 20 g of the pellets were sealed in a glass tube together with a silver piece (15 mm x 2 mm x 0.2 mm) and heated at 1505C for 300 hr to measure the electrical resistance of the silver piece with a milli-ohmmeter, Examples 1 to 9 and Comparative Examples 1 to 11 The components shown in the Table was mixed with polybutylene terephthalate, and a pelletized composition was prepared therefrom by making use of an extruder. The above-described evaluation was conducted with respect to the pellets thus prepared and various specimens prepared from the pellets by injection molding.
The results are shown in Table 1.

E i ~ _ O O _-E i I I~; i I _ --' - -- ~ ~ ~ ~`~ ~ _ 6 0 _ ~ == ,, = _ ..
X --I I ~i i I _ i Le _ c~ O I _ _ O O _ ".~ = = = = = . O
E i.:I I ~i = l _ l -- ~ ~ ~ ~ ~ = _ ~-- X O , . N ~ = = ~ = =
O X' ~¦ I L~ i ¦ ¦ e _ ~ ~ ~ l O ~ X
~ ~ = - = .~ a E x --i ! -- I .i i I _ I -- -- i ~ ~ _ o _ _ 6 , = = ., . , o - ~ - X ~ ~ . I ' 1. e ~ ~ ~~ L ~ _ _ O
..., _, ~. , 3 ~. ~
a c ~ ~ O~ ~ ~ ~ ¦ O. o _ ~E
E~ - _ _ . , -- .--. --.. _ _.. _ _ .. _ ......... _ _.. , ~ = ' ~C
:. ~o L
O ,E O
, ,, CO "
35~ . _~ . L ~ . ~ C -- C O Ul O
c , ~ E' ~' N 'J ,,, C
, , 9 . ' . ~ , -- ~J V O
. , 0 ~ ~ ~ E , c ~ ~' F ~ o ~
_ _ ~ J N _~ , , ~0 ~.

U e _ =, ~ ' ~
= = = = =
e G I I -- ~ C~ C~~ ~ -- X
c~ X G I ~ = O u~ O :~
= oL~ o r~
E I I I-- ~i --i I -- ~ C G~ O _ ~ <I X lo . ~ In O O Ln cq o ~_ I I C-- = G I G I I O c~ ~i o _ G C e ~ ~ X ~_ . ~O ~ O O = N G
U ~ ~ ~ I ~i G I O I I O c~ ~ , O _ _ e G <I O G=
Ge~ O O =~
~i :~ ¦ I ~i G I G _ G c~ O G ~ ~_ O O ~
;j ~ _ O C ~ e~ ~ o . ~ I I ~i G I O ¦ G ~ ~ ~i O O 1O 0 0 0 0 ~ G ~ =
XCi e-- I I ~; G I G _ I O C~ ~i G G O = c~ O O :~
~O = O O ~ .
i O I ~ e O l = ~ O G ~ ~ -E. U u~ o O ~ _ c~ ~i G I O I I O C~ ~i = O C O = e O O C~
~:~O . O ~ . ~
X i ~ I I i ~i I ~C I I C ~Oco C = O ~C O O C~ , C 0 1.0 c~ O
Cq ~i eC = I O O C: O O ~ ~ ~ ~
N U O N . ~ ::
~e~ O E E I ~ I E
3 ~ ~ = E I I E
__.___________ _-.-------- ------~~~~~~~~~~~~~~~~~ e E -- "~ 1 o C ' j D C ~ e . O -- e E ~ ~
D C e O h . .. h ~ ~J O O ID
E ; o~ "~ ~ e ~ ~j nl o ~ ~
7e , ~ ~, ~ ~~ IP O ~ U 3 tt~ U /~ _ _ 'J J N . C ~ h _l '~OT:T.C---'.'JO~ ~-- (571~.~0~iOI~1 T7~--. L~ TT7n ::- 13335Q9

Claims (5)

1. A flame-retardant polybutylene terephthalate resin composition comprising, based upon the total weight of the composition:
(A) a polybutylene terephthalate base resin;
(B) 0.5 to 25% by weight of a halogenated bisimide represented by the general formula:

wherein R1 is a divalent organic group and R2 and R3 are each a divalent organic group, provided that at least one of R2 and R3 has at least one halogen atom;
(C) 0.05 to 5% by weight of a polytetrafluoroethylene resin;
(D) 0 to 60% by weight of an inorganic filler; and (E) 0.05 to 5% by weight of a low molecular weight polyethylene .

2. A flame-retardant composition as in claim 1, wherein said polybutylene terephthalate base resin is a polybutylene terephthalate homopolymer or a polybutylene terephthalate copolymer having at least 80% by weight of polybutylene terephthalate units.

3. A flame-retardant composition as in claim 1 or 2, wherein said halogenated bisimide is an alkylenebistetrabromo-phthalimide.

4. A flame-retardant composition as in claim 1 or 2, which further comprises:
(F) 0.01 to 5% by weight of at least one amine or amide stabilizer.

5. A molded article for electrical components prepared by molding a composition according to claim 1 or 2.