Document dn863pVwppRXxv8w89MYeQ1G

United States Patent [19] Nakano et al. [11] Patent Number: 5,043,371 [45] Date of Patent: Aug. 27, 1991 [54] FLAME-RETARDANT POLYBUTYLENE TEREPHTHALATE RESIN COMPOSITION AND MOLDED ARTICLE FOR ELECTRICAL COMPONENT [75] Inventors: Michio Nakano, Fuji; Hirouki Amono, Shimizu; Hiroshi Nakatsuji, Fuji, ail of Japan [73] Assignee: Polyplastics Co., Ltd., Osaka, Japan [21] Appl. No.: 309,867 [22] Filed: Feb. 14, 1989 [30] Foreign Application Priority Data Mar. 2. 1988 [JP] Japan ...................................... 63-49337 [51] Int. Cl.s...............................................C08K5/34 [52] U.S. Cl....................................... 524/86; 524/87; 524/94 [58] Field of Search ............................. 524/86, 87, 94 [56] References Cited U.S. PATENT DOCUMENTS 3,671,487 6/1972 Abolins ................................ 260/873 3,950.301 4/1976 Balog et al......................... 525/41 1 X 4,119,607 10/1978 Gergen et al..................... 525/169 X 4.313,903 2/1982 Bier ....................................... 264/328 4,344,878 8/1982 Dolce ................................. 260/45.75 4,373,047 2/1983 Cohen et al............................ 525/177 4.374,220 2/1983 Sonnenberg ........................... 260/45 4,399,244 8/1983 Bier ......................................... 260/40 FOREIGN PATENT DOCUMENTS OilU79 6/1984 European Pat. OfT. . 0225645 6/1987 European Pat. Off. . OTHER PUBLICATIONS Plastics Engineering, vol. 43, No. 7, Jul. 1987, pp. 39-41, Brookfield Center, Conn., U.S.; L. Bourland: "Ultra-high-flow PP Speeds Up PET Crystallization". Primary Examiner--Joseph L. Schofer Assistant Examiner--J. M. Reddick Attorney, Agent, or Firm--Nixon & Vanderhye [57] 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. Oo II c II c /\ /\ Ri N-- Rl-S Ri \/ C \c/ oII oII (I) 5 Claims, No Drawings 5,043,371 12 solving all of the above-described problems even FLAME-RETARDANT POLYBUTYLENE though it was possible to solve part of the problems. TEREPHTHALATE RESIN COMPOSITION AND Therefore, the development of a flame-retardant PBT MOLDED ARTICLE FOR ELECTRICAL COMPONENT composition capable of solving all of the above5 described problems has eagerly been desired. FIELD OF INVENTION In general, the molding of polybutylene terephthalate is relatively easy as compared with that of polyethylene The invention relates to a polybutylene terephthalate terephthalate. However, in recent years, there are many composition having excellent flame retardancy and cases where a further reduction in the production cost well-balanced performance characteristics. The compo 10 of molded articles is desired. In particular, there is an sitions of this invention show improvements in mold- increasing demand for the enhancement of productivity ability (e.g., flow molding cycle, prevention of mold through shortening of the molding cycle (i.e., the so- staining, etc.) and prevent the staining of metals when called high-cycle molding). In general, the present in used for electrical components and the like. vention is directed to a before "flame-retardant"; flame- BACKGROUND AND SUMMARY OF THE INVENTION 15 retardant PBT composition which has excellent flame retardancy and well-balanced performance characteris tics and is free from the above-described drawbacks. Polybutylene terephthalate and copolymers com Particularly, the compositions of the present invention posed of at least 80% by weight of polybutylene tere shorten the molding cycle and the realization of the phthalate (hereinafter generically referred to as "PBT") 20 high-cycle molding and causes no problems with re have been used as engineering plastics for widespread spect to mold staining. applications, such as automobiles and electrical and Specifically, the present invention relates to a flame- electronic equipment, because they are crystalline ther retardant polybutylene terephthalate resin composition moplastic resins exhibiting excellent mechanical and comprising: electrical properties as well as well as excellent physical 25 (A) polybutylene terephthalate or a copolymer com and chemical characteristics. posed of at least 80% by weight of polybutylene tere PBT resin compositions compounded with or- phthalate; ganohalogen flame retardants or flame-retardant assis tants for the purpose of imparting flame retardancy have been used previously for applications where flame retardancy is required, such as to from electrical com 30 (B) 0.5 to 25% by weight, based on the composition, of a halogenated bisimide represented by the general formula (1): ponents. However, known PBT resin compositions com pounded with flame retardants and flame-retardant assistants have the following problems. 35 (1) The presence of a flame retardant and an assistant lowers the physical properties of molded articles. O cII cII /\ /\ R2 N--R.1--N Rj \c/ \ c/ O(1) (2) PBT decomposes and deteriorates during the preparation of a composition or molding due to the interaction of a flame retardant and an assistant. (3) A flame retardant and an assistant in addition to 40 wherein R; is a divalent organic group and Rz and R3 decomposition by-products thereof cause molds to cor are each a divalent organic group, provided that at least rode and stain so that the dimensional accuracy of one of R2 and R3 has at least one halogen atom; molded articles and fabrication efficiency are lowered. (C) 0.05 to 5% by weight, based on the composition, (4) A flame retardant and an assistant in addition to 45 of a polytetrafluoroethylene resin; and decomposition by-products thereof bring about the (D) 0 to 60% by weight, based on the composition, of formation of spots on molded articles which spoil the an inorganic filler. appearance and performance of the same. In addition, the present invention provides a PBT (5) Poor compatibility of a flame retardant with the composition having desired performance and effects resin brings about oozing of the flame retardant on the 50 further improved by incorporating an olefinic polymer surface of a molded article to cause various problems. (E) and/or a stabilizer (F) to the abovementioned fun (6) The flow of the resin is kindered, so that it be damental components. comes difficult to conduct molding^ (7) When a molded article is used, a flame retardant and an assistant used therewith or by-products of the 55 DETAILED DESCRIPTION OF THE INVENTION decomposition thereof corrode or stain a metal in The components constituting the composition of the contact therewith or present in the vicinity thereof, present invention will now be described in more detail. which hinders the functions of electrical components. First of all, the PBT resin to be used as component For example, when a molded article is used in electrical (A) in the present invention is polybutylene terephthal components having electric contacts made of a metal 60 ate prepared by polycondensation of 1,4-butanediol (e.g., housings or boards of switches, relays, etc.), there with terephthalic acid or a lower alcohol ester thereof occurs various problems including a remarkable in and may be a copolymer composed of 80% by weight of crease in the electrical resistance of the contact result polybutylene terephthalate. Examples of the comono ing from the staining of the contact metal during the mer include aliphatic and aromatic polybasic acids, long-term use thereof. 65 such as isophthalic acid, naphthalenedicarboxylic acid, Various proposals have been made in order to solve adipic acid, sebacic acid, trimellitic acid and succinic these problems. However, it was very difficult to pre acid, or ester forming derivatives thereof; lower alkyl- pare a flame-retardant PBT composition capable of ene glycols such as 1,3-propanediol, 1,6-hexanediol, and 5,043,371 34 1,8-octanediol; aromatic alcohols such as bisphenol A tic effect attained by a combination with the other com and 4,4'-dihydroxybiphenyI; an adduct of an alcohol ponents). with an alkylene oxide, such as an adduct of bisphenol In the present invention, ti is preferred to use compo A with 2 mol of propylene oxide; and polyhydroxy nent B) in combination with a flame-retardant assistant. compounds, such as glycerin and pentaerythritol, or 5 Examples of the flame-retardant assistant include ester forming derivatives thereof. metallic oxides and hydroxides such as antimony tri- Polybutylene terephthalate is particularly preferable. odixe, antimony halide, aluminum hydroxide, and mag In the present invention, the halogenated bisimide as nesium hydroxide. The flame-retardant assistant is component (B) to be compounded with the PBT resin added in an amount of 0 to 15% by weight, preferably as component (A) is a compound represented by the 10 1 to 10% by weight based on the total amount of the following general formula (1): composition. The polytetrafluoroethylene resin as component (C) 0O c11 c11 to be used in the present invention can be prepared by known processes and is easily commercially available. /\ /\ N--R, -- N \/ \/ 15 In general, this resin is a white solid prepared by poly merization of tetrafluoroethylene in an aqueous medium CC in the presence of a radical catalyst. Polytetrafluoroeth 11 II OO ylene as component (C) may be one having any degree of polymerization (viscosity) selected according to fab- R; is a divalent organic group such as an alkylene, 20 ricability, dispersibility, and other physical properties of preferably having 1 to 25 carbon atoms, and an arylene, the composition. The particle diameter as well is widely preferably having 6 to 0 carbon atoms. More preferable adjustable from 0.05 fim to several millimeters. Further, is an alkylene having 1 to 6 carbon atoms. Examples it is also possible to use polytetrafluoroethylene having thereof include methylene, ethylene, 1,4-butylene, 1,6hexamethyiene, phenylene, 4,4'-methylenediphenylene, 25 any shape from granule to above-described shape and fiber. With respect to the particle diameter, suitable 4,4'-oxydiphenyiene, xylylene, tetrachloroxylylene, and shape and size may be experimentally selected depend tetrabromoxylylene. Among them, ethylene, butylene, ing upon the fabricability and the intended property and and hexamethylene are preferable. At least one, prefera effect of the composition. The amount of incorporation bly both of R2 and R3 are a divalent organic group having at least one halogen atom, preferably a divalent 30 of component (C) is 0.05 to 5% by weight, preferably 0.05 to 3% by weight based on the total amount of the halogenated aromatic group and generally a divalent composition. When the amount of component (C) is too phenylene group having 1 to 4 halogen atoms. The small, the flame retardancy becomes unsatisfactory in halogen is preferably bromo, particularly preferably connection with other components, and in particular no 4-bromophenylene group. Examples of the bisimide represented by the formula 35 sufficient improvement can be attained in the dripping as determined by the combustion test according to UL- (1) as component (B) include the following compounds: 94, while when it is too large, the physical properties N,N'-(p- and m-phenylene)-bis[3,4,5,6-tetrachloroph- are unfavorably lowered due to poor dispersion. thalimide], N,N'-(p- and m-phenylene)-bis[3,4,5,6-tetra- The feature of the present invention resides in a syn bromophthalimide], N,N'-(methylene-di-p-phenylene)bis[3,4,5,6-tetrachlorophthalimide], N,N'-(methylenedi-p-phenylene)-bis[3,4,5,6-tetrabromophthalimide], N,N'-(oxy-di-p-phenylene)-bis(3,4,5,6-tetrachlorophthalimide], N,N'-(oxy-di-p-phenylene)-bis[ 3,4,5,6-tetrabromophthalimide], N,N'-(p- and m-phenyiene)-bischloroendoimide, *N,N'-(p- and m-tetrachloroxylylene)-bis[3,4,5,6-tetrachlorophthalimide], *N,N'-(p- 40 45 ergistic effect attained by a combination of the follow ing three components, i.e., (A) PBT, (B) halogenated bisimide, and (C) tetrafluoroethylene. The effect of the present invention cannot be attained when any one of the above-described three components is absent or re placed by other substance. That is, a combined use of a flame retardant as com and m-tetrachloroxylylene)bis[3,4,5,6-tetrabromoph- ponent (B) and polytetrafluoroethylene as component thalimide], *N,N'-(p- and m-tetrachloroxylylene)-bis- (C) according to the present invention brings about the chloroendoimide, N,N`-( l ,2-ethylene)-bischloroendoi- formation of a composition having various advantages mide, N,N'-(1 2-ethylene)-bis[3,4,5,6-tetrabromoph- 50 such as an ability to impart excellent flame retardancy thalimide], N,N'-bis( 1,2,3,4,5-pentabromobenzyl)- to crystalline PBT, freedom from dripping, excellent pyromellitimide, and N,N'-bis(2,4,6-tribromophenyl)- dispersion among the three components, freedom from pyromellitimide. the occurrence of spots on the surface of a molded With respect to the compounds marked with *, the article as opposed to other flame-retardant composi tetrahaloxylene group is 1,2,4,5-tetrahaIoxylylene or 55 tions liable to bring about such unfavorable phenomena, 1,3,4,5-tetrahaloxylylene. excellent mechanical properties, freedom from the oc Among them, a lower alkylenebistetrabromophthali- currence of separation and deposition of each compo mide is preferable, and N,N'-ethylenebistetrabromoph- nent during fabrication or use at a high temperature, thalimide is particularly preferable. and freedom from corrosion of metal by virtue of excel The content of component (B) is 0.5 to 25% by 60 lent stability because of little or no occurrence of de weight, preferably 1 to 15% by weight based on the composition and deterioration of each component. total amount of the composition. When the content is The flame-retardant PBT composition comprising too large, mechanical and physical properties, thermal components (A), (B), and (C) has advantages such as an stability, etc. are lowered, so that the appearance of the effect of increasing the rate of solidification of the PBT resin is spoiled. On the other hand, when it is too small, 65 resin through the rise of the crystallization temperature not only the flame retardancy becomes unsatisfactory and acceleration of crystallization during solidification but also no sufficient effect can be attained with respect by virtue of the coexistence of components (B) and (C), to the high cycle moldability derived from the synergis excellent flow, little or no occurrence of deposition and 5,043,371 56 corrosion on a mold, and an effect of enabling high stability superior to those of known flame retardant- cycle molding through great contribution to shortening containing PBT compositions and it can exert a remark of the molding cycle. The above-described advantages able effect on the molding cycle and the prevention of can be attained by synergism of components (A), (B), staining of metal. However, a further improved effect and (C) according to the present invention. Therefore, 5 can be attained when the above-described components for example, a polyester elastomer wherein a large (A) and (D) are used in combination with an olefinic amount of polyoxyalkylene glycol is used as a monomer polymer as component (E) and/or an amine or amide cannot exhibit any effect of shortening the molding stabilizer as component (F). cycle even when the same polyester is used as compo The term "olefinic polymer" as component (E) used nent (A). 10 herein is intended to mean any polymer or copolymer Next, with respect to the inorganic filler as compo mainly composed of constituent units comprising an nent (D), it is preferable to incorporate this component olefin, and examples thereof include polyethylene, poly for the purpose of preparing a molded article having propylene and modifications thereof and copolymers, excellent performance with respect to mechanical such as ethylene/propylene, ethylene/vinyl acetate, strengths, heat resistance, dimensional stability (resis 15 ethylene/acrylic ester and ethylene/acrylic acid co tance to deformation and warping) and electrical prop polymers, and modifications thereof. In particular, it is erties, and fibrous, granulated and flaky fillers may be preferable from the viewpoint of attaining the purpose used depending upon the intended purposes. of the present invention that these olefinic polymers Examples of the fibrous filler include inorganic fi have low molecular weights. Further, it is more prefera brous materials, e.g., glass fiber, carbon fiber, silica 20 ble that they be waxy which are poor in itself in the fiber, silica-alumina fiber, zirconia fiber, boron nitride moldability. The amount of incorporation of the olefinic fiber, silicon nitride fiber, boron fiber, potassium tita- polymer is 0.05 to 5% by weight, preferably 0.1 to 3% nate fiber, and fibrous materials of metals such as stain by weight based on the composition. less steel, aluminum, titanium, copper, and brass. Repre sentative examples of the fibrous filler include a glass 25 When the above-described olefinic polymer is used in combination with a particular flame retardant as com fiber and a carbon fiber. It is also possible to sue highmelting organic fibrous materials such as polyamide and acrylic resin. Examples of the particulate filler include carbon black, silica, ground quartz, glass bead, glass powder, silicates such as calcium silicate, aluminum silicate, kao 30 ponent (B) and polytetrafluoroethylene as component (C), it promotes the dispersion of these components, prevents components (B) and (C) from depositing and adhering on the surface of metal such as a mold during molding or standing at a high temperature, exhibits a lin, talc, clay, diatomaceous earth and wollastonite, mold releasing action on the composition of the present metallic oxides such as iron oxide, titanium oxide, zinc invention remarkably superior to that attained by other oxide and alumina, metal carbonates such as calcium releasing agents generally known to the art, and short carbonate and magnesium carbonate, metal sulfates 35 ens the molding cycle, so that it becomes possible to such as calcium sulfate and barium sulfate, and other conduct further improved high cycle molding. fillers such as silicon carbide, silicon nitride, boron ni The amine or amide stabilizer as component (F) is an tride and various metallic powders. amine or an amide compound having an aromatic group Examples of the flaky inorganic material include and preferably a phenylamine, an amine or amide com mica, glass flake, and various metallic foils. 40 pound having, in its molecule, an amido or sterically The above-described inorganic fillers can be used kindering phenolic group. Examples of component (F) clone or in a combination of two or more of them. A include N,N'-hexamethylenebis(3 5-di-tert-butyl-4hy- combined use of a fibrous filler, particularly a glass droxyhydrocinnamide), N,N'-bis[3-(3, 5-di-tert-butyl-4- fiber, with a granular and/or flaky filler is preferable for hydroxyphenyl)propionyl] hydrazine, N-phenyl-N'-iso- attaining a combination of mechanical strengths with 45 propyl-p-phenylenediamine, N,N'-diphenyl-p- dimensional accuracy, electrical properties, etc. phenylenediamine, 4,4'-bis(4-a,a-dimethylbenzyl) di- If necessary, it is preferable to use the above- phenylamine, N-phenylnapththylamine, and N,N'-di-/3- described fillers in combination with a sizing agent or a naphthylphenylenediamine. They may be used alone or surface treatment. Examples of the compound used for in a combination of two or more of them. Among them, this purpose include functional compounds such as 50 N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhy- epoxy compounds, isocyanate compounds, silane com drocinnamide, N,N'-bis[3-(3, 5-di-tert-butyl-4-hydroxy- pounds, and titanate compounds. These compounds phenyl)propionyl]hydrazine, and 4,4'-bis(4-a,a-dime- may be used by previously conducting surface treat thylbenzyl)diphenylamine are particularly preferable. ment or sizing treatment. Alternatively, they may be In the present invention, these amine or amide stabi added together with other components when the com 55 lizers are used in an amount of 0.01 to 5% by weight, ponents are mixed with each other. preferably 0.05 to 2% by weight based on the composi In the present invention, the amount of incorporation tion and effective in improving not only the thermal of the above-described inorganic filler is 0 to 60% by stability of the composition but also the prevention of weight, preferably 5 to 50% by weight based on the staining of a metal. total amount of the composition. When this amount 60 These amine or amide stabilizers suppress the decom exceeds 60% by weight, not only it becomes difficult to position of the composition of the present invention, conduct fabrication but also there occurs a problem particularly components (B) and (C) per se and has a with respect to the mechanical strengths of a molded synergistic effect of suppressing the decomposition of article. The amount of the functional surface treatment PBT by component (B), which not only contributes to used in combination with the inorganic filler is 0 to 10% 65 an improvement in the molding efficiency through pre by weight, preferably 0.05 to 5% by weight. vention of the corrosion and staining of the mold during Even when the composition of the present invention molding but also prevents the corrosion and staining of is used as it is, it has mechanical properties and thermal metal in contact with the molded article of electrical 5,043,371 8 components etc. wherein the molded article is used at a so that it becomes possible to realize high cycle mold high temperature. ing. The composition of the present invention may further (7) The corrosion or staining of a coexisting metal contain a small amount of thermoplastic resin(s) as an (contact) during use of the composition can be effec auxiliary additive. For example, it is also possible to 5 tively prevented. incorporate the following thermoplastic resins in any proportion according to the intended purpose: ethy EXAMPLES lene-acrylic ester copolymer, polyamide, polyacetal, In the Examples, the evaluation of the characteristics polystyrene, styrene-butadiene copolymer, styrene- were conducted by the following methods. (1) Mea butadiene-acrylonitrile copolymer, styrene-butadiene- 10 surement of physical properties acrylic acid (or an ester thereof) copolymer, styrene- tensile test: according to ASTM D 638 acrylonitrile copolymer, polycarbonate, polyurethane, Izod impact strength: according to ASTM D 256 polyphenylene oxide, polyphenylene sulfide, polybuta (2) Residence test (thermal stability) diene, halogenated polyolefin, polyvinyl halide, butyl A sample was allowed to stay within a cylinder of a rubber, and multilayer graft copolymer mainly com- 15 molding machine at a cylinder temperature of 260 C. posed of polyacrylate. for 30 min and then molded into a specimen. The It is a matter of course that in order to impart a de molded specimen was subjected to a tensile strength test sired property to the composition of the present inven to evaluate the thermal stability and deterioration of the tion according to the intended purpose, the composition sample. of the present invention may be compounded with addi- 20 (3) Combustion test (UL-94) lives known to the art, e.g., additives other than the Tests on the flame retardancy and the dripping of the above-described components, such as lubricants, nucle resin during combustion were conducted by making use ating agents, mold releasing agent, antistatic agents, of five specimens (thickness: 1/32 in.) according to the surfactants, plasticizers, colorants, thermal stabilizers, Subject 96 (UL94) of Underwriters' Laboratories. and ultraviolet stabilizers. 25 (4) Measurement of flow The composition of the present invention can be Molding was conducted under the following condi prepared by making use of known equipment and pro tions by making use of a test mold for measurement of cesses commonly employed in the preparation of the rod flow length (cavity: 20 mm in width x 2.0 mm in conventional resin composition. Examples of the pro thickness), and the flow was evaluated based on the cess include (i) one which comprises mixing the individ- 30 flow length (the length of the molded article): ual components, milling and extruding the mixture with molding conditions: an extruder to prepare pellets, and then conducting cylinder temperature: 250 C. molding; (ii) one which comprises preparing pellets injection pressure: 1,000 kg/cm2 each different in the composition, mixing them in prede mold temperature: 60 C. termined amounts and molding the mixture to prepare a 35 (5) Critical molding cycle predetermined molded article; and (iii) one in which a A molded article having a cylindrical bottom (outer molding machine is directly charged with at least one of diameter: 40 mmrj); height: 40 mm; average thickness: 5 the components. Further, in order to attain homogene mm) was molded under the following conditions to ous compounding of the components, it is preferable to determine the critical time (sec) for molding cycle capa employ a process which comprises pulverizing part of 40 ble of providing a molded article having an excellent the resin components into fine powders and mixing appearance. The smaller the numerical value, the better them with the other components. the high cycle moldability. The flame-retardant PBT resin composition of the present invention is molded into various molded articles Molding conditions: cylinder temperature: 250 C. which are required to have flame retardancy, and are 45 very useful when used in electrical components, partic ularly electrical and electronic parts having an electric injection pressure: 1,400 kg/cm2 mold temperature: 90 C. molding cycle: injection-holding time was kept con contact made of metal, such as switches and relays. The PBT composition of the invention has well- balanced functions by virtue of an effective improve- 50 stant to determine cooling time. (6) Visual inspection of molded article A disk (100 rnmrf); thickness: 3 mm) was molded and ment in the following characteristics. (1) Since the composition brings about no deposition observed with the naked eye with respect to the occur rence and the number of spots having different colors on the surface of a mold during molding and has excel lent thermal stability, not only the mold is less suscepti ble to corrosion by a decomposition product or the like 55 and oozing after being left to stand at 120 C. for 72 hr. Evaluation was made based on the following criteria: but also fabrication 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. 60 (4) The composition is excellent in the flame retard spot oozing {( 0 A free small number of spots many spots ( free {X XA small degree of oozing large degree of oozing ancy, 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, 65 (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 X2 mm X0.2 mm) and heated at 150 C. for 300 hr to measure the electrical resistance of the silver piece with a miHi-ohmmeter. 5,043,371 9 10 EXAMPLES 1 TO 9 AND COMPARATIVE EXAMPLES 1 TO 11 truder. The above-described evaluation was conducted with respect to the pellets thus prepared and various specimens prepared from the pellets by injection mold The components shown in the Table was mixed with ing. polybutylene terephthalate, and a pelletized composi 5 The results are shown in Table 1. tion was prepared therefrom by making use of an ex- TABLE 1 Comp. Comp. Comp. Comp. Comp. unit Ex. 1 Ex. 1 Ex. 2 Ex. 3 Ex. 2 Ex. 4 Ex. 5 composition quality (physical properties) composition quality (phvsical properties) (A) polybutylene terephthalate fflL halogenated bisimide *1 brominated polycarbonate decabromodiphenyl ether antimony trioxide IQ_ polytetrafluoroethylene asbestos (D) glass fiber (E) low-molecular polyethylene (F) stabilizer *2 tensile strength tensile elongation Izod impact strength notch side (notched) anti-notch side residence test residence time: 30 min (tensile strength) combustion test (UL-94) number of drips critical molding cycle (cooling time) flow visual inspection spot oozing electrical resistance (silver piece) (A) polybutylene terephthalate halogenated bisimide *1 brominated polycarbonate decabromodiphenyl ether antimony trioxide (Q_ polytetrafluoroethylene asbestos (D) glass fiber (E) low-molecular polyethylene (F) stabilizer -2 tensile strength tensile elongation Izod impact strength notch side (notched) anti-notch side residence test residence time: 30 min (tensile strength) combustion test (UL-94) number of drips critical molding cycle (cooling time) flow visual inspection spot oozing electrical resistance (silver piece) wt % 80.5 80.5 80.5 75.0 80.2 13.0 13.0 13.0 " -- 13.0 -- -- -- " -- -- 13.0 -- -- 5.0 5.0 5.0 5.0 5.0 " kg/cm 2 % kg cm/cm kg cm/cm kg/cm 2 0.5 -- 1.0 -- 545 !2 3.4 27 245 0.5 -- 1.0 -- 533 10 3.0 22 173 0.5 -- 1.0 -- 542 11 3.0 20 193 6.0 -- 1.0 -- 548 8 2.9 20 208 0.5 -- 1.0 0.3 542 12 3.6 26 266 _ drips sec mm -- -- mfl unit wt % V-0 0 14 . 590 O O 39 V-0 0 21 485 A A 130 Ex. 3 Ex. 4 72.5 57.5 V-0 0 22 510 A X 110 Ex. 5 52.5 V-0 0 16 450 X O 37 Ex. 6 52.9 V-0 0 14 600 O O 19 Ex. 7 56.5 7.0 7.0 12.0 12.0 7.0 ---------- ---------- 5.0 5.0 5.0 5.0 5.0 " " kg/cm2 % kgcm/cm kgc m/cm kg/cm2 0.5 -- 15 -- -- 1060 3.2 5.6 40 108 0.5 -- 30 -- -- 1430 2.4 8.5 65 11090 0.5 -- 30 -- -- 1460 2.4 5.7 0.1 -- 30 -- 1400 2.5 8.5 66 64 1020 1020 0.5 -- 30 1.0 -- 1430 2.5 8.8 70 1070 drips sec mm -- -- mO unit V-0 0 9 303 O 0 20 V-0 0 9 270 O O 22 V-0 0 9 249 O O 24 V-0 0 9 253 o () 23 Comp. Ex. 6 Comp. Ex. 7 Comp. Ex. 8 -V-0 0 9 283 O O 21 Comp. Ex. 9 80.2 13.0 -- 5.0 0.5 -- 1.0 0.3 536 11 3.2 21 190 V-l 2 21 490 A o 39 Ex. 8 57.2 7.0 -- -- 5.0 0.5 -- 30 -- 0.3 1420 2.5 5.6 65 1120 V-0 0 9 268 O O 16 Comp. Ex. 10 80.7 13.0 -- -- 5.0 -- -- 1.0 0.3 538 10 3.0 20 221 V-2 5 17 485 O O 25 Ex. 9 56.2 7.0 -- -- 5.0 05 -- 30 1.0 0.3 1425 2.6 8.7 68 1180 V-0 0 8 279 0 O 15 Comp. Ex. 11 composition (A) polybutylene terephthalate halogenated bisimide *1 brominated polycarbonate decabromodiphenyl ether antimony tnoxide wt % 57.5 57.5 56.5 ___ 7.0 -- -- -- 7.0 7.0 5.0 5.0 5.0 58.0 54.0 7.0 7.0 ---- --~ 5.0 50 52.7 -- 7.0 5.0 polytetrafluoroethylene asbestos (D) glass fiber (E) low-molecular polyethylene (F) stabilizer *2 0.5 0.5 0.5 ------ 30 30 30 -- -- 1.0 -- -- 6.3 ---- -- -- 4.0 4.0 30 30 30 ---- 1.0 ---- 0.3 11 quality tensile strength (physical tensile elongation properties) Izod impact strength notch side (notched) anti-notch side residence test residence time: 30 min (tensile strength) combustion test (UL-94) number of drips critical molding cycle (cooling time) flow visual inspection spot oozing electrical resistance (silver piece) i: ethylenebisteirabromophthalimide 2: 4.4'-bis(4-a,a-dimethylbenzyl)diphenyIimine 5,043,371 TABLE l-continued kg/cm2 % kg cm/cm kgcm/cm kg/cm2 1350 2.2 3.0 42 702 1370 2.3 8.0 46 781 -- drips sec mm -- -- mQ V-t 1 14 220 A O 80 V-0 0 14 229 A X 75 1380 2.4 3.1 45 883 V-0 6 14 230 A X 35 12 1430 2.0 6.5 40 815 1460 1.6 7.5 50 903 V-2 5 12 225 A O 27 V-0 0 12 201 X O 28 1430 1.5 7.0 40 887 V-0 0 14 205 X X 39 What is claimed is: 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: oo II II cc /\ /\ Ri N--R| --N Rj `\ / \/ CC II II oo 30 wherein R; 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 polybu tylene 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 alkylenebistetrabromophthalimid. 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 pre pared by molding a composition according to claim 1 or 2. ***** 40 45 50 55 60 65