Document Ed6RR12mxMQwKzVoX8MRwmz10

United States Patent [] Izutu et al. [ii] 4,105,622 [45] Aug. 8,1978 [54] PROCESS FOR THE PREPARATION OF FLAME RETARDANT THERMOPLASTIC RESIN COMPOSITIONS [75] Inventors: Hitoshi Izutu, Osaka; Ryoichi Ishikawa, Takaishi, both of Japan [73] Assignee: Dainippon Inc. & Chemicals Inc., Tokyo, Japan [21] Appl. No.: 721,327 [22] Filed: Sep. 7,1976 [30] Foreign Application Priority Data Mar. 22, 1976 [JP] Japan ............................... 51-29867 [51] Int. Cl/...................... C08G 18/34; C08K 3/40; C08K 3/10; C08K 3/34 [52] U.S. Q............................. 260/37 N; 260/45.8 A; 260/75 NP; 260/858; 260/830 P [58] Field of Search....... 260/75 NP, 77.5 R, 2.5 BB, 260/830 P, 45.8 A, 2.5 AK, 37 N [56] References Cited U.S. PATENT DOCUMENTS 3,148,167 3,264,233 3,359,218 3,525,779 3,625,872 9/1964 8/1966 12/1967 8/1970 12/1971 Keplinger ............. ....... 260/45.8 A Trescher et al........ ....... 260/75 NP Wiles.................... ....... 260/75 NP Hawkins ............... ........ 260/830 P Ashida.................. ...... 260/2.5 AK 3,629,167 3,775,355 3,884,849 3,916,060 12/1971 11/1973 5/1975 10/1975 Allen et al........................ 260/830 P Jellinek et al................. 260/45.8 A Molbert....................... 260/2.5 BB Fish et al...................... 260/2.5 AK OTHER PUBLICATIONS Encyclopedia of Polymer Science & Technology, vol. 5, John Wiley (Interscience) N.Y., 1966, pp. 430-435. Whittington's Dictionary of Plastics, Technomic Publ. Co., Stamford, CT (USA) 06902, pp. 85-86. Primary Examiner--H.S. Cookeram Attorney, Agent, or Firm--Sherman & Shalloway [57] ABSTRACT A process for preparing a flame retardant thermoplastic resin composition which comprises heat mixing and kneading 100 parts by weight of a mixture consisting of a hydroxyl-terminated low molecular weight thermo plastic polyester (A) and a polyfunctional isocyanate (B), or a reaction product of (A) and (B), with 1.5-25 parts by weight, calculated as halogen, of a specific halogenated epoxy compound, 0.3-15 parts by weight, calculated as antimony, of an antimony compound, and, as the case may be, 0-10 parts by weight of asbestos, and/or 0-60% by weight, based on the total weight of the resin composition obtained, of glass fibers. 20 Claims, No Drawings 4,105,622 12 the decomposition of the polyester is accelerated as a PROCESS FOR THE PREPARATION OF FLAME result of, say, the elimination of the hydrogen halide. RETARDANT THERMOPLASTIC RESIN Moreover, a considerable amount of the halogenated COMPOSITIONS copolymeric component is necessary for imparting a 5 sufficient flame retardancy, with the consequence that This invention relates to a process for the preparation there is a marked decline in the melting point and heat of flame retardant thermoplastic resin compositions. distortion temperature of the flame retardant thermo More particularly, this invention relates to a process for plastic polyester produced as well as a great decline in preparing a flame retardant thermoplastic resin compo its resistance to attack by chemicals. sition by heat mixing and kneading a mixture, or a reac 10 In consequence of our extensive researches with a tion product, of a hydroxyl-terminated low molecular view to solving the foregoing difficulties pertinent to weight thermoplastic polyester and a polyfunctional isocyanate, with a halogenated epoxy compound, an antimony compound and, as the case may be, asbestos making the thermoplastic polyesters flame retardant, we found that by using as the thermoplastic polyester a hydroxyl-terminated thermoplastic polyester having a and/or glass fibers. 15 hydroxyl value of from 7 to 40 (hereinafter referred to The thermoplastic polyesters, and especially polyeth as relatively low molecular weight polyester) in admix ylene terephthalate and polybutylene terephthalate, are ture with a polyfunctional isocyanate, or a reaction superior in their mechanical properties, heat resistance, product of them, and by choosing as the reaction type resistance to attack by chemicals and electrical proper flame retarding agent a halogenated epoxy compound it ties. Hece, these polyesters are attracting attention in 20 was possible to easily obtain a flame retardant polyester recent years as being well-balanced enginerring plastics. composition excelling in mechanical strength, heat re Of these polyesters, polybutylene terephthalate is espe sistance, moldability, nondissipativeness of the flame cially preferred because of its fast crystallization speed retarding agent and resistance to attack by chemicals. and excellent moldability. However, as in the case with Thus, the present invention intends to provide a pro many of the other thermoplastic resins these thermo 25 cess for preparing a flame retardant thermoplastic resin plastic polyesters have the shortcoming that they are composition which comprises heat mixing and kneading flammable. Hence, it is strongly desired that they be 100 parts by weight of a mixture consisting of a rela made flame retardant. The flameproofing of a thermo tively low molecular weight thermoplastic polyester plastic resin can usually be accomplished readily by (A) and a polyfunctional isocyanate (B), or a reaction uniformly dispersing and mixing a so-called additive 30 product thereof, with 1.5-25 parts by weight, calculated type flame retarding agent in the resin. This likewise applies in the case of such thermoplastic polyesters as, for example, polybutylene terephthalate. However, as halogen, of a halogenated epoxy compound of the formula when a flame retardant thermoplastic polyester is to be obtained by the use of this additive type flame retarding 35 (I) agent, there are such drawbacks as (1) that unless the amount added of the flame retarding agent is great, the flame retardant effect is not sufficient; (2) that the com patibility of the flame retarding agent and the polyester is poor or that since the flame retarding agent and the 40 polyester are not chemically bound, there is brought about a great decline in the physical properties that are inherently possessed by the polyesters; (3) that the flame retarding agent makes its way to the surface of the molded product for the reasons given in (2), above, to 45 impair the appearance of the molded product or that when the product is held at an elevated temperature wherein X is either hydrogen, chlorine or bromine, Y is exceeding room temperature, there is a drastic decline either an alkylidene group of 1-6 carbon atoms, cy- in the flame retardancy due to the dissipation of the cloalkylidene, --S--, --SO--, --SO2--, or --O--, Z is flame retarding agent; (4) that the flame retarding agent 50 hydrogen or methyl, and n is 0-15, decomposes during the processing steps to cause a great 0.3--15 parts by weight, calculated as antimony, of an decline in the physical properties of the polyester; and antimony compound, 0-10 parts by weight of asbestos (5) that in consequence of the decomposition of the and 0-60% by weight, based on the total weight of the flame retarding agent there is a decline in the rate of resin composition obtained, of glass fibers. retention of the heat resistant strengths. 55 The process of the present invention differs from the Of the foregoing drawbacks, those of especially (2) conventional techniques in which there is generally and (3) can be overcome by the use of the so-called employed a method of choosing and adding to the ther reaction type flame retarding agent. That is to say, it is moplastic polyester a suitable flame retarding agent possible to employ a process of obtaining a flame retar whose addition brings about the least possible decline in dant thermoplastic polyester by copolymerizing either a 60 the physical properties of the thermoplastic polyesters, halogenated glycol or a halogenated dicarboxylic acid and is a unique process in that it is directed to modifying at the time of polycondensing the thermoplastic polyes the thermoplastic polyester itself so as to be suitable for ter. This process is however an extremely difficult one rendering it flame retardant. in actual practice. Since the temperature at which the In the present invention, a hydroxyl-terminated low polycondensation of polyesters is carried out is usually 65 molecular weight thermoplastic polyester (A) and a 200-300' C., the foregoing halogenated copolymeric polyfunctional isocyanate (B) can be used as merely a component becomes unstable, and there is a marked mixture, or it can also be used as a chain extended reac impairment of the polycondensation reaction, because tion product by carrying out the chain extension of the 4,105,622 relatively low molecular weight polyester with the diisocyanate-1,4, hexane diisocyanate-1,5, 4-methyl- polyfunctional isocyanate at 200-300 C. The chain hexane diisocyanate-1,2,3-methylhexane diisocyanate- extension can be readily accomplished by the method 1,4, 2-benzyl-propane diisocyanate-1,3, 2,4-diphenyl- described in, say, Japanese Laid-Open Patent Applica hexane diisocyanate-1,6, methylcyclohexane diisocya- tion No. 99741/74. 5 nate, 4,4'-dicyclohexymethane diisocyanate, isopropyl- As the relatively low molecular weight polyesters idene bis(4-cyclohexylisocyanate), p-phenylene diisocy (A) to be used in the present invention, there can be anate, m-phenylene diisocyanate, 4,4'-diphenyl diisocy named such aromatic polyesters as, for example, poly anate, 1,4-naphthylene diisocyanate, 1,5-naphthaylene ethylene terephthalate, polyethylene-2,6-naphthalate, diisocyanate, 1,8-naphthylene diisocyanate, 2,6- polypropylene terephthalate, polybutylene terephthal 10 naphthylene diisocyanate, 1-methyl-phenylene ate, polybutylene-2,6-naphthalate and polycyclohex- diisocyanate-2,4, 1-methyl-phenylene diisocyanate-2,6, anedimethylene terephthalate. Usable also are these xylylene diisocyanate-1,3,-xylylene diisocyanate-1,4, aromatic polyesters with which have been compolym- 4,4'-diisocyanate diphenyl ether, 2,2'-diisocyanate di erized a polycarboxylic acid such as, for example, iso- ethyl ether, 2,2'-diisocyanate diethyl sulfite, 4,4'- phthalic acid, adipic acid, sebacic acid and trimellitic 15 diisocyanate diphenylmethane, hydrogenated 4,4'- acid and/or a polyhydric alcohol such as, for example, diisocyanate dipheliylmethane and isophorone diisocya ethylene glycol, propylene glycol, butylene glycol, nate; as well as 1-methyl-phenylene diisocyanate-2,4 diethylene glycol, triethylene glycol, pentamethylene dimer and 1-methyl-phenylene diisocyanate-2,6 dimer. glycol, hexamethylene glycol, glycerol, trimethylolpro- Further the polyisocyanate having 3 or more isocyanate pane, pentaerythritol and the alkylene oxide adduct of 20 groups in their molecular structure, e.g., triphenylme- bisphenol A. Of these relatively low molecular weight thane-4,4', 4"-triisocyanate and crude 4,4'-diisocyanate- polyesters (A), especially preferred is polybutylene diphenylmethane can be used in conjunction with the terephthalate because of its relatively low melting point hereinbefore-indicated polyfunctional isocyanates. Of which makes it possible to lower the extrusion tempera these, the purified diphenylmethane diisocyanates are ture, with the consequence that the decomposition of 25 most preferred in view of their reactivity and safety. the halogenated epoxy compound, the flame retarding The foregoing polyfunctional isocyanate is suitably agent can be reduced and, in addition, since the result used in an amount, based on 100 parts by weight of the ing flame retardant polyester composition possesses relatively low molecular weight polyester, calculated as superior physical properties in a well-balanced manner. follows: (0.8-2.5) X (isocyanate equivalent of polyfunctional isocyanate (B)) (hydroxyl equivalent of relatively low molecular weight polyester (A)) Further, it is preferred that the relatively low molec ular weight polyester (A) be one whose ends are almost all occupied by hydroxyl groups and that the amount of 35 the carboxyl groups be as small as possible. Practically, said low molecular weight polyester is suitably one whose intrinsic viscosity (measured in a 6:4 solvent mixture of phenol and tetrachloroethane at 30 C., this to apply equally hereinafter) is 0.15-0.6 dl/g and hydroxyl value (the number of milligrams of potassium 40 X 100 parts by weight. (The isocyanate equivalent, as here used, is the molecular weight of the polyfunctional isocyanate per isocyanate group, while the hydroxyl equivalent, as here used, is the molecular weight of the hydroxide required to neutralize one gram of specimen) is 7-40, and more preferably one whose intrinsic viscos ity is 0.25-0.5 dl/g and hydroxyl value is 9-29. If, in this case, the hydroxyl value is less than 7, the amount 45 added of the polyfunctional isocyanate used becomes less to result in a reduction in the amount reacted of the halogenated epoxy compound, with a consequence that a marked decline takes place in the physical properties relatively low molecular weight polyester per hydroxyl group.) Of the 100 parts by weight of the mixture or reaction product consisting of a relatively low molecular weight polyester (A) and a polyfunctional isocyanate (B), up to 30% by weight of the polyester can be substituted by other organic polymers in carrying out the present in vention. of the resulting flame retardant thermoplastic polyester. 50 The halogenated epoxy compound used in this inven On the other hand, when the hydroxyl value exceeds tion is a compound having the general formula 40, this also is undesirable, since the amount added of the polyfunctional isocyanate becomes great, with the consequence that the resulting thermoplastic polyester becomes one whose properties depart from those inher- 55 ently possessed by the thermoplastic polyesters. Hence, there is a possibility that the objects of the invention cannot be achieved. The polyfunctional isocyanates (B) usable in this invention include such aliphatic, alicyclic and aromatic 60 diisocyanates as, for example, trimethylene diisocya nate, tetramethylene diisocyanate, pentamethylene di isocyanate, hexamethylene diisocyanate, heptamethy- lene diisocyanate, octamethylene diisocyanate, nona- wherein X is either hydrogen, chlorine or bromine, Y is methylene diisocyanate, decamethylene diisocyanate,, 65 either an alkylidene group of 1-6 carbon atoms, cy- propane diisocyanate-1,2, butane diisocyanate-1,2, pen cloalkylidene, --S--, --SO--, --S02--, or --O--, Z is tane diisocyanate-1,2, pentane diisocyanate-1,3, hexane hydrogen or methyl, and n is an integer 0-15, preferably diisocyanate-1,2, hexane diisocyanate-1,3, hexane 1-12. 4,105,622 56 This epoxy compound can be readily obtained by either weight is also undesirable, since the physical properties of such methods as, say, that of condensing a compound inherently possessed by the thermoplastic polyester are of the formula impaired. As the antimony compound to be used in the present x x 5 invention, there can be named such, for example, an antimony pentoxide, antimony trioxide, antimony trisul fide, antimony trichloride, and antimony pentachloride, antimony tribromide, antimony pentabromide, of which especially to be preferred is antimony trioxide. The 10 antimony compound is used in an amount of 0.3-15 parts by weight, and preferably 0.5-13 parts by weight, wherein X and Y are as hereinabove defined, with epi- per 100 parts by weight of the mixture or reaction prod chlorohydrin and/or methylepichlorohydrin or that of uct of the relatively low molecular weight polyester (A) reacting a compound of the formula and the polyfunctional isocyanate (B). When this com 15 pound is added in an amount less than 0.3 part by weight, a high1 degree of flame retardancy cannot be obtained. On the other hand, when the amount exceeds 15 parts by weight, this also is undesireable, since the mechanical properties and heat resistance of the result 20 ing flame retardant thermoplastic resin composition suffer. When the antimony compound used is one con wherein X, Y and Z are as hereinabove defined, with a taining a halogen, the amount of halogen contained in compound of the formula the antimony compound is combined with that con tained in the halogenated epoxy compound when mak X x 25 ing the calculation of the amount to be used of the latter. Asbestos, which is usable in the present invention, has the effect of preventing dripping when the shaped arti cle bums. It is used in an amount not exceeding 10 parts 30 by weight, and preferably 1-7 part by weight, per 100 parts by weight of the mixture of reaction product of the relatively low molecular weight polyester (A) and the polyfunctional isocyanate (B). The use of the asbes wherein X and Y are as hereinabove defined. If the tos in an amount in excess of 10 parts by weight is not foregoing epoxy compound is shown by a more specific general formula, it is as follows: 35 desirable, since no further improvement is had in the effect of preventing dripping by the use of asbestos in such excess. Furthermore, there is a decline in the other properties of the resinous composition. While the thermoplastic resin composition rendered 40 flame retardant obtained by the present invention is valuable even without the incorporation of glass fibers, the incorporation of glass fibers is desirable in view of such effects as the reinforcement of the products ob tained from the composition. Preferred as such glass 45 fibers are those of 1-30 millimeters in length, which are incorporated in an amount of 0-60% by weight, and preferably 10-50% by weight, based on a whole amount of the composition. The incorporation of the glass fibers in an amount in excess of 60% by weight is undesirable, 50 because the moldability of the flame retardant thermo plastic resin composition becomes unsatisfactory. It is known to obtain a flame retardant thermoplastic polyester by incorporating in a flammable polyester- ,especially the fiber glass reinforced polybutylene tere- wherein X! is either hydrogen, chlorine or bromine, 55 phthalate, the halogenated epoxy resin that is used in with the limitation that when / and m are zero, it is the present invention. However, when a comparison is either chlorine or bromine, X2 is either chlorine or bro made between the case of known art where there is used mine, and Y and Z are as hereinbefore defined, the sum as the thermoplastic polyester one having an intrinsic of / and m being an integer of from 0-15, preferably viscosity [17] of 0.7-1.2 dl/g (e.g. polybutylene tere- 1-12. 60 phthalate) and the case of the invention where there is This compound is used in an amount, calculated as used a polymer obtained by transforming a relatively halogen, of 1.5-25 parts by weight, and preferably 3-22 low molecular weight polyester (intrinsic viscosity of parts by weight, based on 100 parts by weight of the 0.15-0.6 dl/g) into a high polymer with a polyfunc mixture or reaction product of the relatively low molec tional isocyanate or a mixture of a relatively low molec ular weight polyester and the polyfunctional isocya 65 ular weight polyester and a polyfunctional isocyanate, nate. When this amount is less than 1.5 parts by weight, there is basically a great difference between the two a high degree of flame retardancy cannot be obtained. cases. In the former case the effect of the halogenated On the other hand, an amount exceeding 25 parts by epoxy compound is merely that of an additive type 4,105,622 8 flame retarding agent, whereas in the latter case the tion are suitably chosen in accordance with the class of isocyanate resulting from the dissociation of the ure the relatively low molecular weight polyester and its thane bond reacts with the hydroxyl group of the halo- hydroxyl value, the class and amount added of the poly genated epoxy compound and/or the terminal epoxy functional isocyanate and the heat mixing and kneading group of the halogenated epoxy compound reacts with 5 conditions. When the composition of the starting mate active hydrogen atom of the urethane bond so that the rials and the mixing and kneading conditions are chosen halogenated epoxy compound as the flame retarding agent and the polymer that has been transformed into a so that the reaction between one mole of the haloge nated epoxy compound used and three or more moles of high polymer are chemically bound to form either a the polyfunctional isocyanate cannot be ignored, it is graft or block polymer. This is apparent from the fact 10 preferred that the low molecular weight polyester be that when the flame retardant thermoplastic resin com rendered into a high polymer by reacting the relatively position is submitted to a Soxhlet extraction under re low molecular weight polyester and the polyfunctional flux until a constant weight is reached, using toluene, a isocyanate in advance in order to prohibit the occu solvent for the halogenated epoxy compound, a major rence of a three-dimensional reaction. proportion of the flame retarding agent is extracted in 15 Further, in this invention the hydroxyl group of the the case of the compositions of the conventional meth halogenated epoxy compound and the isocyanate group ods, whereas the amount of the flame retarding agent of the polyfunctional isocyanate react at the time of the extracted in the case of the composition of the present heat mixing and kneading operation. Hence, the addi invention process is negligible. tion of a known polyurethanation catalyst is a preferred Hence, in the case of the composition prepared by 20 practice so as to make it possible to adjust the reaction incorporating a halogenated epoxy compound as flame as desired. As this polyurethanation catalyst, mention retarding agent into a thermoplastic polyester not modi can be made of such compounds as, for example, 1,4- fied by means of a polyfunctional isocyanate, the flame diazabicyclo-(2,2,2)-octane, N,N,N',N',N''-pentame- retarding agent demonstrates only effect of an additive thyldiethyltriamine, N,N-dimethylcyclohexy!amine, type flame retarding agent and, consequently, there is 25 N-methyldicyclohexylamine, N,N,N',N"-tetramethyl- noted a decline in the mechanical properties, the heat propylenediamine, triethylamine, N,N,N',N'-tetrame- resistance and moldability that are inherently possessed thylhexamethylenediamine, N-methylmorpholine, N- by the thermoplastic polyesters. Another serious draw ethylmorpholine, N,N-dimethylethanolamine, N,N-die- back was that the flame retarding agent could be ex- thylethanolamine, l,8-diazabicyclo(5,4,0) undecene-7 tracted with the usual organic chemicals such as tolu- 30 and the salts thereof, stannous octate, dibutyltin oxide, ene. On the other hand, in the composition of the pres cobalt naphthenate, stannous chloride, tetra-n-butyl tin, ent invention the halogenated epoxy compound is stannic chloride, trimethyltin hydroxide and dimethyl- bound to the thermoplastic polyester through the me tin dichloride. This catalyst is suitably added in an dium of the polyfunctional isocyanate to become tras- amount of 0.001-2% by weight per 100 parts by weight formed into either a block or graft polymer, with the 35 of the halogenated epoxy compound. consequence that there is no decline in the mechanical The heat mixing and kneading in this invention is strengths that are inherently possessed by the thermo carried out by means of an apparatus which can cause plastic polyester, as a result of the addition of the flame the reaction between the relatively' low molecular retarding agent. Furthermore, the heat resistance and weight polyester and the polyfunctional isocyanate and moldability are improved and, in addition, the resis 40 the reaction between the reaction product thereof and tance to attack by chemicals is also improved in that the the halogenated epoxy compound to take place, and flame retarding agent is not extracted by means of such moreover, in which the antimony compound and, as the organic chemicals as toluene. case may be, the glass fibers and/or asbestos can be In practicing the process of the present invention, the uniformly mixed. Specifically, most preferred is the use starting materials are first premixed and then heat- 45 of an extruder for this purpose, and a barrel temperature mixed and kneaded. By such treatment a reaction takes of 200-300" C., and preferably 205,'-260 C., is place between the halogenated epoxy compound and either the mixture or reaction product consisting of the relatively low molecular weight polyester and the poly adopted. While the dwell time of the starting materials inside the extruder is greatly influenced by the classes and amounts added of the polyfunctional isocyanate functional isocyanate and, at the same time, the uniform 50 and the halogenated epoxy compound, and the barrel dispersion of the antimony compound and, as the case temperature of the extruder, usually a dwell time of may be, the asbestos and/or glass fibers are effectively 0.2-20 minutes, and preferably 0.4-10 minutes, is suit carried out. While it is possible to use one which has able. When the dwell time is shorter than 0.2 minute, the been transformed into a high polymer by reacting the reaction of the halogenated epoxy compound does not relatively low molecular weight polyester with the 55 take place sufficiently. On the other hand, when 20 polyfunctional isocyanate in advance, this need not be minutes is exceeded, this also is undesirable, since the necessarily done. For instance, it is also possible to decomposition of the halogenated epoxy compound practice a procedure wherein the chain extension of the becomes excessive. relatively low molecular weight polyester by the poly Especially in the case where an extruder is to be used, functional isocyanate is effected in the heat mixing and 60 considerations must be given to the following points in kneading step while the halogenated epoxy compound its selection. First, in such cases where the mixing and is also reacted therewith and, while the halogenated kneading performance of the extruder is exceedingly epoxy compound is also reacted therewith and, at the poor, the reaction between the mixture or reaction same time, the antimony compound and, as the case product of the relatively low molecular weight polyes may be, asbestos and/or the glass fibers are uniformly 65 ter and the polyfunctional isocyanate and the haloge dispersed in the reaction product. In adopting the fore nated epoxy compound becomes inadequate and, more going two methods, the class and amount added of the over, the dispersion of the antimony compound as well halogenated epoxy compound to be used in this inven as the asbestos and/or glass fibers that may be used as 4,!U5,bZ2 9 10 the case may be becomes unsatisfactory. Secondly, in such cases where the mixing and kneading performance of the extruder is extremely good, there is the drawback that there occurs an excessive cutting of the glass fibers at the time of the mixing and kneading operation of 5 result in the mechanical properties of the shaped article not being achieved to the desired degree. Thus, most suitable in the case where glass fibers are to be used is an extruder in which reaction or dispersion of the starting materials used is good and, in addition, the mixing and 10 kneading performance is effected such that the glass fibers having lengths of 0.1-2 millimeters are uniformly dispersed in the resulting resin composition. Again, it is 6 parts by weight of antimony trioxide and 54 parts by weight of 6-mm-long chopped glass fibers treated with an advantage to use an extruder provided with a vent 15 a vinylsilane type coupling agent, following which the for removal of bubbles. mixture was mixed for 30 seconds. Pellets were then The composition of this invention may be incorpo prepared under identical conditions as in Referential rated with such additives as crystal nucleating agents, Example and measured for their physical properties, fillers, pigments, dyes, plasticisers, mold release agents, with the following results: melting point 222 C., tensile lubricants, thermal stabilizers, ultraviolet absorbents, 20 strength 1380 kg/cm2, flexural strength 1980 kg/cm2, blowing agents, coupling agents, etc. The antimony notched Izod impact strength 8.9 kg-cm/cm, and flex compounds, asbestos and glass fibers that are usable in ural strength retention after 14 days at 155 C. 96%. this invention may be added at the time of the synthesis There was noted no decline in the physical properties as of the relatively low molecular weight polyester or at compared with the non-flame retardant composition of the time of the reaction of the relatively low molecular 25 Referential Example. Further, there was noted no weight polyester and the polyfunctional isocyanate or bleeding (emergence to the surface of the shaped arti subsequent to these reactions. cle) at all of the flame retarding agent in the shaped The flame retardant thermoplastic resin composition article after 14 days at 155 C. Further, the flammability obtained by this invention can be molded by the usual molding procedures, i.e., injection molding, extrusion molding and compression molding. 30 in accordance with the method of subject 94 of the Underwriters' Laboratories (UL 94) (1/16 inch) was UL 94V-0. On the other hand, when the crushed shaped article was submitted to Soxhlet extraction The following Examples and Controls will serve to under reflux with toluene until a constant weight was more fully illustrate the present invention. reached, the amount extracted of the brominated epoxy REFERENTIAL EXAMPLE 35 compound was an exceedingly small amount of 0.55 Synthesis of a high polymer of glass fiber-containing part by weight as compared with the 20 parts by weight, the amount in which it was used. relatively low molecular weight polyester. 95.79 parts by weight of a low molecular weight CONTROL 1 polybutylene terephthalate (intrinsic viscosity 0.38 40 Pellets were prepared by operating exactly as in Ex dl/g) of melting point 220 C. and hydroxyl value 14 ample 1 but using 20 parts by weight of hexabromoben- obtained by polycondensing dimethyl terephthalate zene, a so-called additive type flame retarding agent, with 1,4-butanediol was reacted with 4.21 parts by instead of 20 parts by weight of the brominated epoxy weight of 4,4'-diphenylmethane diisocyanate at 220 C. compound as the flame retarding agent. When the so to obtain a polymer having an intrinsic viscosity of 0.93 45 obtained pellets were tested as in Example 1, the flame dl/g. To 100 parts by weight of this polymer were retardancy (1/16 inch) was UL 94V-O, but the mechan added 42.86 parts by weight of 6-mm-long chopped ical strengths and heat resistance were extremely poor, glass fibers treated with a vinylsilane type coupling when compared with those of Example 1, as indicated agent followed by mixing the polymer and glass fibers by the following results: tensile strength 1150 kg/cm2, for 30 seconds. The so obtained mixture was then fed to 50 flexural strength 1550 kg/cm2, notched Izod impact a vent-equipped full flight-type 65-mm extruder, and strength 5.8 kg-cm/cm, and flexural strength retention pellets were prepared at such an extrusion speed that the dwell time of the starting materials inside the barrel would be 2 minutes. When these pellets were then made 55 after 14 days at 155 C. 52%. Further, there was noted after 14 days at 155 C. a bleeding at the surface of the shaped article of the hexabromobenzene, the flame re tarding agent. into test pieces and measured for their physical proper ties, the following results were obtained: melting point CONTROL 2 223 C., tensile strength 1320 kg/cm2, flexural strength Pellets were prepared by operating exactly as in Ex 1940 kg/cm2, notched Izod impact strength 9.0 kg- ample 1, except that 100 parts by weight of polybutyl cm/cm, and flexural strength retention after 14 days at 60 ene terephthalate not modified by a polyfunctional iso 155 C. 98%. cyanate and of hydroxyl value 3 and intrinsic viscosity EXAMPLE 1 0.92 dl/g was used instead of 100 parts by weight of the polymer of intrinsic viscosity 0.93dl/g used therein. To 100 parts by weight of the polymer of intrinisic When the so obtained pellets are tested as in Example 1, viscosity 0.93/dl/g used in Referential Example were 65 the flame retardancy (1/16 inch) was UL 94-0, but the added 20 parts by weight of a brominated epoxy com mechanical strengths and heat resistance were poor, pound (average degree of polymerization n=4, bro when compared with those of Example 1, as indicated mine content 52 weight %) of the formula by the following results: tensile strength 1210 kg/cm2, 4,105,622 11 12 flexural strength 1750 kg/cm2, notched Izod impact but the mechanical properties were poor in that the strength 6.3 kg-cm/cm, flexural strength after 14 days at tensile strength was 820 kg/cm2 and the flexural 155' C. 76%. Further, when the pellets were extracted strength was 1300 kg/cm2. Further when the pellets with toluene by the Soxhlet method, 17.6 parts by were extracted with toluene by the Soxhlet method, weight of the 20 parts by weight of the brominated 5 17.1 parts by weight of the 20 parts by weight of the epoxy compound used was extracted. Hence, it was brominated epoxy compound used was extracted. noted that there was hardly no reaction of the epoxy compound. EXAMPLE 5 EXAMPLE 2 Pellets were prepared by operating exactly as in Ex ample 1 but with the further addition of 3 parts by Ten parts by weight of the brominated epoxy com weight of asbestos. When the resulting pellets were then pound used in Example 1, 48 parts by weight of 6-mm- tested as in Example 1, the flame retardancy (1/32 inch) long chopped glass fibers treated with a vinylsilane type was UL 94V-0, the tensile strength was 1370 kg/cm2, coupling agent and 2 parts by weight of antimony triox the flexural strength was 1960 kg/cm2, and the flexural ide were added to 100 parts by weight of the polymer of strength retention| after 14 days at 155` C. was 96%. intrinsic viscosity 0.93 dl/g used in Example 1, and Further, when the pellets were extracted with toluene pellets were prepared by operating exactly as in Exam by the Soxhlet method, 0.53 part by weight of the 20 ple 1. When the so obtained pellets were then tested as parts by weight of the brominated epoxy compound in Example 1, the flame retardancy (J inch) was UL used was extracted. The results show that dripping was 94V-0, the tensile strength was 1340 kg/cm2 and the prevented by the use of the asbestos and an improve notched Izod impact strength was 9.0kg-cm/cm. Fur ment was noted in the flame retardancy over that of ther, when the pellets were extracted with toluene by Example 1. the Soxhlet method, only 0.28 part by weight of the 10 parts by weight of the brominated epoxy compound EXAMPLE 6 used was extracted. Thus, the results were the same as Pellets were prepared by operating exactly as in Ex in the case of Example 1 even though the amount used ample 1, except that instead of 100 parts by weight of of the brominated epoxy compound was reduced. the polymer of intrinsic viscosity 0.93 dl/g used therein EXAMPLE 3 100 parts by weight of a polymer of intrinsic viscosity 0.87 dl/g obtained by reacting 95.32 parts by weight of Example 1 was repeated but using a barrel tempera a low molecular weight polyethylene terephthalate of ture of 220' C. and a dwell time of the starting materials hydroxyl value 20 with 4.68 parts by weight of 4,4' of 5 minutes in the step of preparing the pellets using a diphenylmethane diisocyanate was used with a barrel 65-mm extruder. When the so obtained pellets were temperature of the extruder of 260* C. When the result tested as in Example 1, the flame retardancy (1/16 inch) ing pellets were then tested as in Example 1, the flame was UL 94V-0, the tensile strength was 1420 kg/cm2 retardancy (1/16 inch) was UL 94V-0, the tensile and the notched Izod impact strength was 9.5 kg- strength was 1240 kg/cm2 and the notched Izod impact cm/cm. Further, when the pellets were extracted with strength was 7.5 kg-cm/cm. Further, when the pellets toluene by the Soxhlet method, only 0.18 part by weight were extracted with toluene by the Soxhlet method, of the 20 parts by weight of brominated epoxy com only 0.36 part by weight of the 20 parts by weight of the pound used was extracted. brominated epoxy compound used was extracted. The EXAMPLE 4 results were thus nearly the same even when a low molecular weight polyethylene terephthalate was used. Pellets were prepared by operating exactly as in Ex ample 1 but using instead of 100 parts by weight of the EXAMPLE 7 polymer of intrinsic viscosity 0.93 dl/g used therein, 100 Pellets were prepared by operating exactly as in Ex parts by weight of a polymer of intrinsic viscosity 0.88 ample 1, however, without using 54 parts by weight of dl/g obtained by reacting 97 parts by weight of a low the glass fibers but using 5 parts by weight of asbestos. molecular weight polybutylene terephthalate of instrin- The resulting pellets had a flame retardancy (1/32 inch) sic viscosity 0.51 dl/g and hydroxyl value 9 with 3 parts of UL 94V-0, a flexural strength of 880 kg/cm2, a by weight of 4,4'-diphenylmethane diisocyanate at 240' notched Izod impact strength of 5.9 kg-cm/cm, and a C. When the resulting pellets were tested as in Example flexural strength retention after 14 days at 155 C. of 1, the flame retardancy (1/16 inch) was UL 94V-0, the 94%. Further, when the brominated epoxy compound tensile strength was 1300 kg/cm2, the flexural strength used was extracted with toluene, only 0.56 part by was 1910 kg/cm2 and the notched Izod impact strength weight of 20 parts by weight used was extracted. Again, was 8.5 kg-cm/cm. Further, when the pellets were there was no bleeding at all of the flame retarding agent extracted with toluene by the Soxhlet method, 0.63 part at the surface of the shaped article after 14 days at 155' by weight of the 20 parts by weight of the brominated C. epoxy compound used was extracted. CONTROL 4 CONTROL 3 Example 7 was repeated but using instead of the bro Pellets were prepared by operating exactly as in Ex minated epoxy compound 14.4 parts by weight of tetra- ample 4 but using instead of 100 parts by weight of the bromophthalic anhydride. While the flame retardancy polymer of intrinsic viscosity 0.88 dl/g used therein, 100 (1/32 inch) of the resulting pellets was UL 94V-0, their parts by weight of a low molecular weight polybutylene mechanical strengths and heat resistance were ex terephthalate of intrinsic value 0.51 dl/g and hydroxyl tremely poor when compared with those of Example 7 value 9 not modified by a polyfunctional isocyanate. in that their flexural strength was 610 kg/cm2, notched When the resulting pellets were tested as in said exam Izod impact strength was 4.1 kg-cm/cm, and flexural ple, the flame retardancy (1/16 inch) was UL 94V-0, strength retention after 14 days at 155 C. was 42%. 4,lUD,02id 13 14 Further, bleeding of the tetrabromophthalic anhydride, 1. A process for preparing a flame retardant thermo the flame retarding agent, was noted at the surface of plastic resin composition which comprises heat mixing the shaped article after 14 days at 155 C. and kneading 100 parts by weight of a mixture consist EXAMPLE 8 5 ing of a hydroxyl-terminated low molecular weight thermoplastic polyester (A) selected from the group To 100 parts by weight of a mixture consisting of 95 consisting of polyethylene terephthalate, polypropylene parts by weight of a low molecular weight polybutylene terephthalate of intrinsic viscosity 0.36 dl/g and hy terephthalate and polybutylene terephthalate having a hydroxyl value of from 7 to 40 and an intrinsic viscos droxyl value 15 and 5 parts by weight of 4,4'- ity, as measured in a 6:4 solvent mixture of phenol and diphenylmethane diisocyanate were added 15 parts by 10 tetrachloroethane at 30 C, of 0.15-0.6 dl/g and a poly weight of a brominated epoxy compound (average de functional isocyanate (B), or a reaction product of (A) gree of polymerization n=6, bromine content 51.5% by and (B), with 1.5-25 parts by weight, calculated as halo weight) of the formula gen, of a halogenated epoxy compound of the formula Br Br 15 wherein X, is either hydrogen, chlorine or bromine, with the proviso that when / and m are zero, it is either weight of 6-mm-long chopped glass fiber treated with an aminosilane type coupling agent, and the mixture was mixed for 30 seconds. This was followed by prepar ing the pellets as in Referential Example and measurement of the physical properties thereof. The flame retardancy (1/16 inch) of the pellets was UL 94V-0, 30 chlorine or bromine, X2is either chlorine or bromine, Y is selected from the group consisting of an alkylidene group of 1-6 carbon atoms, cycloalkylidene, --S--, --SO--, --S02-- and --O--, Z is selected from the group consisting of hydrogen or methyl, and n is a while the tensile strength was 1350 kg/cm2, flexural strength was 1980 kg/cm2, notched Izod impact number from 0-15,0.3-15 parts by weight, calculated as antimony, of an antimony compound, 0.10 parts by strength was 8.5 kg-cm/cm, and flexural strength reten- 35 weight of asbestos, and 0-60% by weight, based on the tion after 14 days at 155 C. was 95%. Further, when total weight of the resin composition obtained of glass the pellets were extracted with toluene by the Soxhlet fibers. method, 0.65 part by weight of the brominated epoxy 2. The process of claim 1 wherein the amount in compound used was extracted. which said polyfunctional isocyanate (B) is used rela 40 tive to 100 parts by weight of said hydroxyl-terminated EXAMPLE 9 low molecular weight thermoplastic polyester (A) is Pellets were prepared by operating exactly as in Ex calculated as follows: ample 8, except that the brominated epoxy compound was used in an amount of 20 parts by weight instead of 15 parts by weight, while 50 parts by weight of the glass 45 fibers was not used but 1.5 parts by weight of asbestos (0.8 - 2.5) X (isocyanate equivalent of polvfunctional isocyanate fifl) (hydroxy] equivalent of low molecular weight polyester (A)) and 0.01 part by weight of dibutyltin dilaurate were used. The resulting pellets had a flame retardancy (1/16 inch) of UL 94V-0, a flexural strength of 810 kg/cm2, a notched Izod impact strength of 5.4 kg-cm/cm, and a 50 flexural strength retention after 14 days at 155' C. of X 100 parts by weight. 3. The process of claim 1 wherein said antimony compound is at least one compound selected from the group consisting of antimony trioxide, antimony pen- 90%. Further, when the brominated epoxy compound toxide, antimony trisulfide, antimony trichloride, anti used was extracted with toluene, only 0.59 part by mony pentachloride, antimony tribromide and anti weight of the 20 parts by weight used was extracted. mony pentabromide. 4. The process of claim 1 wherein said glass fibers are CONTROL 5 55 used in an amount of 10-60% by weight of the whole Example 8 was repeated but without using 5 parts by composition. weight of the 4,4'-diphenylmethane diisocyanate and 5. The process of claim 1 which comprises carrying 0.01 part by weight of the dibutyltin dilaurate. In this out the heat mixing and kneading by means of an ex case, however, the melt viscosity of the product was 60 truder with a barrel temperature of 200-300 C. about 2000 centipoises at 250 C., with the consequence that satisfactory test pieces could not be prepared by the 6. A flame retardant thermoplastic resin composition produced by the process of claim 1. use of the usual injection molding machine, and the 7. A shaped article obtained by using the flame retar pieces were extremely fragile. When the brominated dant thermoplastic resin composition obtained in claim epoxy compound used was extracted with toluene, 17.9 65 1. parts by weight of the 20 parts by weight used was 8. A shaped article obtained by using the flame retar extracted. dant thermoplastic resin composition obtained in claim We claim: 1. 4,105,622 15 16 9. A shaped article obtained by using the flame retar 18. The process of claim 1 in which the asbestos is dant thermoplastic resin composition obtained in claim used in an amount of from 1-7 parts by weight, per 100 2. parts by weight of the mixture or reaction product of 10. A shaped article obtained by using the flame retar (A) and (B). dant thermoplastic resin composition obtained in claim 5 19. A flame retardant thermoplastic resin composi 3. tion produced by the process of claim 1 in which the 11. A shaped article obtained by using the flame retar hydroxylterminated low molecular weight thermoplas dant thermoplastic resin composition obtained in claim tic polyester (A) is an aromatic polyester selected from 4. 12. A shaped article obtained by using the flame retar dant thermoplastic resin composition obtained in claim 5. 13. The process of claim 1 in which the aromatic 10 the group consisting of polyethylene terephthalate, polypropylene terephthalate, and polybutylene tere phthalate, said polyfunctional isocyanate (B) is selected from the group consisting of trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocya nate; hexamethylene diisocyanate, heptamethylene di- polyester (A) is polybutylene terephthalate. 14. The process of claim 13 in which the polybutylene 15 isocyanate, octamethylene diisocyanate, nonamethy lene diisocyanate, decamethylene diisocyanate, propane terephthalate polyester (A) has an intrinsic viscosity, as diisocyanate-1,2, butane diisocyanate-1,2, pentane measured in a 6:4 solvent mixture of phenol and tetrachloroethylene at 30 C., of 0.25-0.5 dl/g and a hy diisocyanate-1,2, pentane diisocyanate-1,3, hexane diisocyanate-1,2, hexane diisocyanate-1,3 hexane droxyl value of 9-29. 20 diisocyanate-1,4, hexane diisocyanate-1,5, 4-methyl- 15. The process of claim 1 in which the polyfunc hexane diisocyanate-1,2,3-methyl-hexane diisocyanate- tional isocyanate (B) is a member selected from the 1,4, 2-benzyl-propane diisocyanate-1,3, 2,4-diphenyl- group consisting of trimethylene diisocyanate, tetra- hexane diisocyanate-1,6, methylcyclohexane diisocya methylene, diisocyanate, pentamethylene diisocyanate, nate, 4,4'-dicyclohexymethane diisocyanate, isopropyl- hexamethylene diisocyanate, heptamethylene diisocya 25 idene bis(4-cyclohexylisocyanate), p-phenyl diisocya nate, octamethylene diisocyanate, nonamethylene diiso nate, 1,4-naphthylene diisocyanate, 1,5-naphthylene cyanate, decamethylene diisocyanate, propane diisocyanate, 1,8-naphthylene diisocyanate, 2,6- diisocyanate-1,2, butane diisocyanate-1,2, pentane naphthylene diisocyanate, l-methyl-phenylene diisocyanate-1,2, pentane diisocyanate-1,3, hexane diisocyanate-2,4, 1-methylphenylene diisocyanate-2,6, diisocyanate-1,2, hexane diisocyanate-1,3, hexane 30 xylylene diisocyanate-1,3, xylylene diisocyanate-1,4, diisocyanate-1,4, hexane diisocyanate-1,5, 4-methyl- 4,4'-diisocyanate diphenyl ether, 2,2'-diisocyanate di hexane diisocyanate-1,2, 3-methyl-hexane diisocyanate- ethyl ether, 2,2'-diisocyanate diethyl sulfite, 4,4'- 1,4, 2-benzyl-propane diisocyanate-1,3, 2,4-diphenyl- diisocyanate diphenylmethane, hydrogenated 4,4'- hexane diisocyanate-1,6, methylcyclohexane diisocya diisocyanate diphenylmethane and isophorone diisocya- nate, 4-4'-dicyclohexymethane diisocyanate, isopropyl- 35 nate, n is a number from 1-12, said antimony compound idene bis(4-cyclohexylisocyanate), p-phenyl diisocya is at least one compound selected from the group con nate, 1,4-naphthylene diisocyanate, 1,5-naphthylene sisting of antimony trioxide, antimony pentoxide, anti diisocyanate, 1,8-naphthylene diisocyanate, 2,6naphthylene diisocyanate, l-methyl-phenylene diisocyanate-2,4, l-methyl-phenylene diisocyanate-2,6, xylylene diisocyanate-1,3, xylylene diisocyanate-1,4, 4,4'-diisocyanate diphenyl ether, 2,2'-diisocyanate di 40 mony trisulfide, antimony trichloride, antimony penta- chloride, antimony tribromide and antimony pentabromide and the amount in which the polyfunctional isocy anate (B) is used relative to 100 parts by weight of the hydroxyl-terminated low molecular weight ther mopolyester (A) is calculated as follows: ethyl ether, 2,2'-diisocyanate diethyl sulfite, 4,4'diisocyanate diphenylmethane, hydrogenated 4,4'diisocyanate diphenylmethane and isophorone diisocya 45 nate. (0.8-2.5) X (isocyanate equivalent of polyfunctional isocyanate (BU (hydroxyl equivalent of 100 molecular weight polyester (A)) 16. The method of claim 1 in which n is a number of 20. A flame retardant thermoplastic resin composi from 1-12. tion produced by the process of claim 1 in which the 17. The process of claim 16 which comprises heat 50 low molecular weight polyester (A) is polybutylene mixing and kneading 100 parts by weight of the mixture terephthalate, said polyfunction isocyanate (B) is 4,4'- of (A) and (B) or reaction product of (A) and (B) with diphenylmethane diisocyanate, and the antimony com 3-22 parts by weight of the halogenated epoxy com pound is antimony trioxide. pound. 55 60 65