United States Patent (19) [11] 3,945,974 Schwarcz Et Al

United States Patent (19) [11] 3,945,974 Schwarcz et al. (45) Mar. 23, 1976

54 SMOKE SUPPRESSANTS FOR 2,855,266 l Of 1958 James ...... 260/45.75 2,948,638 8/1960 Baird...... 260/45.75 HALOGEN-CONTAINING PLASTIC 3,202,567 8/1965 Muri et al...... 106/15 FP COMPOSITIONS 3,705,128 12/1972 Knowles...... 260/45.75 75) Inventors: Joseph Schwarcz, Highland Park; 3,766, 57 10/1973 Parts...... 260/45.75 Bernard Engelbart, Trenton; 3,770,577 1 1/1973 Humpbrey...... 260/45.75 Edward L. White, Freehold, all of N.J. OTHER PUBLICATIONS 73 Assignee: NL Industries, Inc., New York, Journal of the American Chemical Society Vol. 61, N.Y. No. 12 pp. 3241 to 3244 Dec. 19, 1939. (22 Filed: Dec. 20, 1973 21) Appl. No.: 426,492 Primary Examiner-V. P. Hoke 52 U.S. C.260/31.8 R; 260/45.7 R; 260/45.75 W; 57 ABSTRACT 260/45.75 B (5) Int. Cl...... C08J 3/20 Zinc is added to a halogen-containing plastic composi 58 Field of Search. 260/45.75 R, 45.7 R, 45.75 B, tion with or without a flame retardant additive to 260/45.75 W, 45.75 K, 29. R serve as a smoke suppressant during combustion of the plastic. (56) References Cited UNITED STATES PATENTS 16 Claims, No Drawings 2,772, 59 l/1956 Elliott...... 260/45.75 3,945,974 2 tions and in particular plasticized polyvinyl chloride SMOKE SUPPRESSANTS FOR include zinc dust, zinc oxide, zinc carbonate, normal HALOGEN-CONTAINING PLASTC zinc trimellitate, acid zinc trimellitate, zinc borate, zinc COMPOSITIONS benzoate, zinc caprate, zinc fumarate, tribasic Zinc phosphite, tribasic zinc sulfate-silicate, pentabasic zinc BACKGROUND OF INVENTION sulfate, tribasic zinc phosphate, dibasic zinc phosphate, Plastic materials including plastic sheeting, synthetic pentadecabasic zinc sulfate, tetrabasic zinc sulfate-sili fibers and the like are generally considered to be haz cate, tribasic zinc trimellitate, heptabasic zinc trimeli ardous materials from the standpoint of flammability; tate and decabasic zinc trimellitate. and in many cases it is the practice to add various flame O The zinc dust and all of the foregoing zinc com retardants to the plastic materials to reduce flammabil pounds were tested for smoke suppression effect in ity during combustion. Recently, however, the propen halogen-containing polymer compositions, the Smoke sity of plastics to create large volumes of smoke, when suppression evaluation being made using the National combusted, has come to be regarded as at least as haz Bureau of Standards Smoke Test hereinafter described. ardous, if not more so, than its flammability. Increasing 5 The incorporation of the zinc or zinc compounds into concern with consumer safety and several tragic acci the halogen-containing plastic compositions is effected dents have contributed to the recognition of smoke by blending the zinc or zinc compounds with the com evolution as a significant hazard. In many instances of ponents used in formulating the plastic compositions. fire, the resulting fatalities have been due to smoke which has prevented safe evacuation of a building due 20 PREFERRED EMBODIMENT OF INVENTION to lack of visibility; or to the toxic gases generated The instant invention comprehends the addition of during combustion of the plastic. zinc or a zinc compound to a halogen-containing poly As mentioned above, extensive studies have been mer composition. While it has been discovered that made in the area of flame-retardant additives for halo zinc or any zinc compound is an effective smoke sup gen-containing plastic compositions examples of which 25 pressant in halogen containing polymer compositions are antimony trioxide; antimony pentaoxide, antimony the degree of smoke suppression is not always the silico oxide see U.S. Pat. No. 3,740,245 and other or same, some zinc materials being more effective than ganic and said antimony-silco oxide comprising amor others. In addition to the smoke suppresant effective phous materials prepared by reacting antimony trioxide ness of these zinc materials they may have other effects (SbO) with hydrous silica or hydrous alkali or alka 30 in polymer compositions which effects are known to line earth metal silicates in weight ratio range 1:4 to 1:1 the art as for example some zinc compounds may have attemperatures in the range 400-550°C in an oxygen an adverse effect on heat stability, some zinc com containing atmosphere; the specific gravity of the an pounds are hygroscopic, deliquescent, unstable or cor timony-silico compounds being in the range 2.4 - 3.6 rosive and some may have a beneficial effect on flame and having an index of refraction of from 1.5 to 1.7, 35 retardancy. Therefore, in selecting a preferred zinc inorganic compositions of antimony. Zinc borate has compound to be used in a specific polymer composi been used also as a flame retardant but so far as is tion besides the smoke suppressant efficiency of the known never as a smoke suppressant and always at zinc other considerations such as cost and those men relatively high levels as for example from 3 to 8 parts tioned above must be taken into account. In light of per 100 parts resin since lesser amounts are ineffective 40 these considerations the preferred zinc compound used as a flame retardant. Moreover, the concept of Sup in a specific polymer composition may not necessarily pressing smoke as well as retarding flammability is be the most effective smoke suppresant but one com disclosed in U.S. Pat. No. 3,723, 139 Larkin et all who bining smoke suppressancy with minimum degradation, disclose the addition of antimony oxide in combination maximum flame retardancy, minimum cost etc. As an with sodium antimonate to polyvinyl chloride plastics 45 example, those zinc compounds which exhibit optimum both to minimize flammability and to suppress smok smoke suppression in plasticized PVC are zinc oxide, ling. W Zinc benzoate, Zinc caprate, zinc metaborate and triba It is desirable, however, to provide a smoke suppres sic zinc phosphite. However, these have an adverse sant for halogen-containing polymer compositions effect on heat stability and hence require the addition which may be used alone and preferably in combina 50 of heat stabilizers which is an added expense in the tion with flame retardants and which are more effective total cost of the polymer composition. Examples of zinc than smoke suppressants heretofore known and used. additives which require little or no heat stabilizer addi tives and for this reason are preferred over the foresaid SUMMARY OF INVENTION zinc compounds, even though somewhat less effective The present invention is the discovery that zinc in 55 as smoke suppressants, are zinc carbonate, zinc dust, substantially any form which can generate zinc oxide acid Zinc trimellitate, normal zinc trimelitate, zinc during the combustion of the polymer, i.e. Zinc dust, fumarate, dibasic zinc fumarate, and zinc peroxide. and inorganic or organic compounds of zinc, and in It will be understood, however, that the zinc com amounts at extremely low levels as for example in the pounds listed above are not restrictive but that other range of about 0.5 to 1.00 parts per hundred parts 60 Zinc compounds, inorganic, organic or organo-metallic resin, as zinc oxide, is a superior smoke suppressant for which can generate zinc oxide during combustion in many halogen-containing polymer compositions in intimate mixture with halogen containing polymer cluding polyvinyl chloride, ABS and halogenated un compositions are contemplated within the scope of this saturated polyesters and the like; and that the zinc is invention. effective whether added alone or in combination with a 65 The instant invention is thus concerned with halogen flame retardant additive. The zinc additives which have containing polymer compositions containing zinc or a been found to be effective as smoke suppressants when compound of zinc as a smoke suppressant, and prefer incorporated in halogen-containing polymer composi ably with a flame retardant, the invention being di 3,945,974 3 4. rected particularly to plasticized polyvinyl chloride in TABLE I-continued the form of flexible sheeting, wire insulation, powders, ZINC COMPOUNDS AS SMOKE SUPPRESSANTS massive forms and the like which contain antimony IN FLEXBLE PVC INCLUDING ANTIMONY base flame retardant additives. TROXIDE FAME RETARDANT Concentration Preparation of these halogen-containing polymer Additive Zinccas ZnO) Dm compositions is effected by standard methods and stan Example Additive PHR PHR dard equipment in the art, the amount of zinc added, 8 Zn Benzo- 92 0.5 327 being in the range of from 0.5 to 1.0 parts per 100 parts ate resin expressed in ZnO. 9 Zn Caprate 255 378 A typical polyvinyl chloride formulation containing 10 O Zn Fuma- 1.13 0.5 432 zinc as a smoke suppressant is as follows: *Trimelitate PVC resin - Geon 102 EPF5 (B.F. Goodrich - 100 parts Co.) As shown in the data in Table I above, a polyvinyl Clarite NS-2 (modified dibutyltin maleate - 1.5 parts 15 stabilizer) chloride plastic material containing no zinc had a maxi Dioctyl phthalate - 50 parts mum specific smoke density Dm of 461. In contradis Antimony trioxide (flame retardant) - 3.0 parts tinction all of those tested specimens which contained Zinc Additive (expressed as ZnO) 0.5 - 1.0 parts zinc or zinc dust, or inorganic or organic zinc com pounds, had Dm values which were significantly lower 20 SMOKE TEST than the test specimen containing no zinc. The smoke suppressant capabilities of the zinc or EXAMPLES 1 1-31 zinc compounds used in test specimens of plasticized Additional test specimens were prepared using the halogen-containing polymer compositions was tested procedure described above in which the zinc additive using the National Bureau of Standards (NBS) Smoke 25 was, in all instances, at a concentration of 0.75 PHR (as Density Chamber a detailed description of which is ZnO). The identity of the zinc additives and the corre given in a paper entitled "Method for Measuring sponding Dm values are shown in the Table below. Smoke from Burning Material' by D. Gross, J. J. Lof tus and A. F. Robinsion - in Symposium on Fire Test TABLE II Methods -- Restraint of Smoke 1966 ASTM STP422. 30 ZINC COMPOUNDS ASSMOKE SUPPRESSANTS IN FLEXBLE PVC INCLUDING ANTIMONY American Society Testing Materials 1967 p. 166. TROXDE FLAME RETARDANT According to the NBS method smoke is measured by Concentration optical means wherein a collimated vertical light beam Additive ZincCas Dm passes through the chamber and the variation intensity Example Additive PHR ZnO) PHR 35 None V- A- 454 of the light beam, resulting from the density of the 12 Zinc Oxide 0.75 0.75 286 smoke in the chamer, is measured by a photometer. A 13 Tribasic zinc. 1.2 0.75 327 phosphite comparison between the smoke behavior of two sam 14 Tribasic zinc 2.10 0.75 306 ples, of identical dimensions, is based on the corrected sulfate-sili (for soot deposition) maximum specific smoke density cate 40 15 Pentabasic zinc 1.09 0.75 36 Dm the term Dm being used in the sense defined by sulfate NBS. The specimen producing the lowest Dm will be 16 Tribasic zinc .2 0.75 36 phosphate the superior specimen. 17 Decabasic zinc 1.02 0.75 280 The following examples will further illustrate the sulfate v V novel aspects of the instant invention. 18 Pentadecabasic 0.99 0.75 336 45 zinc sulfate 19 Tetrabasic zinc 2.06 0.75 276 EXAMPLES 1-10 sulfate-sili cate Eleven test specimens were prepared in which zinc 20 Acid zinc tri- 3.04. 0.75 406 and various compounds of zinc were added at a con mellitate stant level of 0.5 PHR (as ZnO) to a plasticized polyvi 21. Normal zinc tri- 2.27 0.75 295 50 mellitate nyl chloride formulation having the composition given 22 Tribasic zinc .83 0.75 300 above. Each test specimen was prepared from a 40 mil trimellitate 23 . Heptabasic zinc 1.49 0.75 288 sheet of flexible PVC and was tested under nonflaming trimellitate conditions in the NBS Smoke Chamber. The DM val 24 Decabasic zinc 39 0.75 285 ues are shown in Table I. trimelitate 55 25 Zinc fumarate 1.66 0.75 376 TABLE I 26 Zinc carbonate 1.04 0.75 324 27 312 Tetrabasic Zinc 1.01 0.75 31 ZINC COMPOUNDS AS SMOKE SUPPRESSANTS Sulfateftribasic IN FLEXIBLE PVC INCLUDING ANTIMONY Zinc Phosphite TRIOXDE FLAME RETARDANT 28 | Tetrabasic Zinc 1.0 0.75 , 295 Concentration Sulfate/Tribasic Additive Zinccas ZnO) Dm Zinc Phosphite 60 29 312 Tribasic Zinc 1.00 0.75 330 Example Additive PHR PHR Phosphite/Tetrabasic None 461 Zinc Sulfate 2 ZnO 0.5 0.5 336 30 Dibasic Zinc Sulfate 1.01, 0.75 297 3 Zn dust 0.4 0.5 407 31 Zinc Peroxide 0.85 0.75 325 4 Zn Carbon- 0.69 0.5 41 ate 65 5 Normal Zn TriMT+ 1.51 0.5 375 6 Acid Zn As will be seen from the data in Table II, in every TriMT: 2.02 0.5 445 instance, the test specimens containing zinc had Dm 7 Zn Borate 1.31 0.5 349 values well below the test specimen containing no zinc. 3,945,974 S 6 EXAMPLES 32-38 TABLE IV COMPARISON BETWEEN PVC POLYMER Another series of tests were conducted using the CONTAINING SMOKE SUPPRESSANT OF same polyvinyl chloride formulation identified above PRIOR ARTAND ZINC except that the flame retardant compound was an an- 5 Concentration timony-silico composition (A-S) instead of antimony Example Additive AdditivePHR ZincasPHR ZnO) Dm trioxide. The test specimens were again prepared from 39 ) 462 40 mil sheeting. In this series of tests a comparison was as Shanti- 13 440 made between the effect of zinc oxide and zinc borate, monate + MgO 4ll either alone or in combination with the (A-S) flame 10 3. Xeniye 0.38 -- retardant the zinc concentration being constant at 0.75 zinc complex (A-S-Z) 6 0.75 314 PHR as zizinc oxide de foror eacnh specimen.specime The r esults of the 4344 Aluminum hydroxide 9.29.95 0.75 246392 tests are shown in Table III below. plus ZnO TABLE III ZNC COMPOUNDS AS SMOKE SUPPRESSANTS IN FLEXIBLE PVC WITH OR WITHOUT (A-S) FAME RETARDANT Concentration Additive ZincCas ZnO) Oxygen Example Additive PHR PHR Dm Index (O.I) 32 None 460 24.9 33 (A-S) 60 412 28.6 34 ZnO 0.75 0.75 235 2S4 35 Zinc borate 2.01 0.75 225 26.4 (37.3% ZnO, 48.1% B2O) 36 (A-S) - ZnO 610.75 0.75 215 283 37 A-S-Z 6 0.75 230 26.2 38 (A-S) - Zinc 612.0 0.75 258 28.1 borate

Reference to Table III will show that a polyvinyl chloride plastic material containing neither a flame 45 Zinc oxide 0.75 0.75 285 retardant nor a smoke suppressant had a smoke density Dm of 460 which is equivalent to saying that the test material, when burning, evolved considerable smoke. From the foregoing tests it is clear that sodium anti By adding the (A-S) flame retardant the Dm value of 35 monate plus magnesium oxide alone and aluminum the plastic was reduced somewhat (412); but when a hydroxide alone are relatively poor smoke suppressants zinc compound was added, i.e. zinc oxide at 0.75 parts as compared to the zinc compounds. It is interesting to per 100 parts resin the Dm value of the plastic dropped note also that aluminum hydroxide alone is a poor to 285. Similarly when zinc borate was used in an smoke suppressant - but when combined with zinc amount 0.75 PHR, as ZnO, and when either zinc oxide 40 oxide the resulting complex has a lower Dm value than or zinc borate was used in combination with the (A-S) either component alone - which suggests a synergistic flame retardant Dm values were extremely low. Fur effect on smoke suppression, ther, it has been found that zinc compounds are equally EXAMPLES 46-52 effective as smoke suppressants when the smoke sup pressant, i.e. zinc compound and the flame retardant is 45 Seven additional test specimens were made using the a simple mechanical mixture, such as A-S-HZnO or A-S same polyvinyl chloride formulation and the same size + zinc borate (Examples 36 and 38); or when the zinc test strips as described in Examples 1-10 above except is added in the form of a complex calcined compound that (A-S) was substituted for antimony trioxide, and (A-S-Z) as in 37. In this connection, tests have shown the amount of zinc oxide used, with or without (A-S) as that although uncalcined zinc is a highly effective 50 flame retardant, was varied - the mixture of zinc oxide smoke suppressant it has an adverse effect on the heat and flame retardant being uncalcined. stability of the polymer composition; but that, in gen TABLE V eral, calcination tends to decrease this adverse effect. SMOKING CHARACTERISTICS OF PVC In all instances, the Dm values were extremely low COMPOSITIONS CONTAINING ZINC 55 OXDE AND (A-S) indicating that the smoking characteristics of the burn Concentration ing plastic had been considerably reduced. Additive Examples (A-S) Zinc Oxide Dm EXAMPLES 39-45 PHR PHR In order to illustrate the superior smoke suppressant 46 (None) (None) 455 60 47 6 O 412 properties of PVC formulations containing zinc as 48 6 0.25 302 compared to PVC formulations containing prior art 49 6 0:50 286 50 6 0.75 215 smoke suppressant, as described, for example, in U.S. 5 6 0.90 256 Pat. No. 3,723, 139 issued Mar. 27, 1973 a series of 52 O 0.75 235 tests were made using PVC test strips prepared accord ing to the formulation given above except that com 65 pounds other than zinc were added as smoke suppres The data in the foregoing Table shows clearly that a sants. The Dm value of the test strips are shown in polyvinyl chloride plastic material containing neither a Table IV below. flame retardant nor smoke suppressant (Example 46) 3,945,974 7 8 had a relatively high maximum specific smoke density TABLE VII-continued (DM); that when the (A-S) flame retardant was used ZINC COMPOUNDS AS SMOKE SUPPRESSANTS IN ABS, alone in an amount of 6 PHR the Dn value of the CHLORINATED POLYETHYLENE (CPE) AND POLY ESTER plastic material was slightly reduced. However, when Additive Zn(as ZnO) zinc was added, as zinc oxide, in amounts ranging from 5 Example Additive Concentrate PHR Dm 0.25 to 0.90 parts per 100 parts resin, the Dm values of PHR 58 ZnO 0.75 0.75 259 the polyvinyl chloride test strips were significantly low POLYESTER ered again showing that zinc is a powerful smoke sup 59 none - 668 pressant in polyvinyl chloride formulations at the indi 60 A-S-Z 2 50 636 61 SbO3. 6 -- 742 cated low concentration levels. 10 62 SbOA-S-Z 8 0.5 686 EXAMPLES 53-54 Additional test strips were made to show the effec In each instance the addition of zinc to the halogen tiveness of zinc as smoke suppressant in rigid PVC, i.e. 15 containing polymer effected a significant reduction in no plasticizer present. The basic formulation, as given smoke evolution. above, was modified by eliminating DOP and antimony The above data demonstrate clearly the superior oxide. A lubricant, 0.25 PHR stearic acid, was added. smoke suppression properties of zinc or zinc com As shown in Table VI below, the zinc oxide addition pounds either alone or in admixture with an antimony acted as an effective smoke suppressant in the rigid type flame retardant such as used in halogen-contain PVC test strips. 20 ing polymer compositions and in particular polyvinyl TABLE VI chloride - as compared to polyvinyl chloride formula ZINCOXIDEAS SMOKE SUPPRESSANT IN RIGID PVC tions containing only an antimony-type flame retardant Example Additive Concentration (PHR) Dm or a combination of antimony oxide and sodium anti 53 none -- 100 25 monate. And further, that certain zinc additions and in 54 Zinc Oxide 0.75 87 particular, acid, normal and basic zinc trimellitates, zinc dust, zinc carbonate, and normal and basic Zinc fumarates, combine good smoke suppresant properties with minimum effect on degradation of the plastic. EXAMPLES 55-62 30 The invention may be carried out in other specific In order to show the effectiveness of zinc or zinc ways than those herein set forth without departing from compounds as smoke suppressant in polymers other the spirit and essential characteristics of the invention, than PVC, a series of test strips were prepared from and the present embodiments are therefore to be con ABS, chlorinated polyethylene and polyester using the sidered in all respects as illustrative and not restrictive, formulations set out below the test strips of ABS and 35 and all changes coming within the meaning and equiva chlorinated polyethylene having a thickness of 40 mils lency range of the appended claims are intended to be and those of the polyester having a thickness of 125 embraced therein. mils the latter being cured with methyl ethyl ketone What is claimed is: peroxide at 82°C for 2 hours. 1. Method for forming a smoke suppressing combus 40 tible polyvinyl chloride composition comprising a poly vinyl chloride resin, a stabilizer, and zinc oxide com ABS FORMULATION prising the steps of adding zinc oxide to the compo Acrylonitrile-Butadiene-Styrene Polymer 100 parts nents of said polyvinyl chloride composition during Calcium Stearate Bromine-Chlorine (fire retardant) 10 formulation thereof, said zinc oxide added in amounts Pentabromophenyl alkyl ether 10 45 in the range of from about 0.2 to no more than about Zinc additive (as indicated) 1.0 part per 100 parts polymer resin. 2. Method for forming a smoke suppressing combus CHLORINATED POLYETHYLENE tible polyvinyl chloride composition comprising adding Chlorinated Polyethylene (42% chlorine) 00 parts Calcium Stearate 1. t finely divided zinc metal to the components of said Clarite NS-2 (modified dibutyltin 50 polyvinyl chloride composition during formulation maleate stabilizer) 1.5 parts thereof said finely divided zinc metal added in amounts Zinc additive (as indicated) in the ranges of from about 0.2 to no more than about POLYESTER 1.0 part calculated as zinc oxide per 100 parts plymer Halogenated polyester 50 parts resin. Non-halogenated polyester 50 55 3. Method for forming a smoke suppressing combus Additive (as indicated) tible polyvinyl chloride composition comprising a poly vinyl chloride resin, a stabilizer, a plasticizer, a flame retardant and zinc oxide comprising the steps of adding The results are shown in the Table below: zinc oxide to the components of said polyvinyl chloride TABLE VII 60 composition during formulation thereof said zinc oxide ZINC COMPOUNDS AS SMOKE SUPPRESSANTS IN ABS, added in amounts in the range of from about 0.2 to no CHLORINATED POLYETHYLENE (CPE) AND POLYESTER more than about 1.0 part per 100 parts polymer resin. Additive Zn(as ZnO) Example Additive Concentrate PHR Dm 4. Method according to claim 3 wherein said flame PHR retardant is a compound of antimony. ABS 65 5. Method according to claim 4 wherein said com 55 One - - 31 pound of antimony comprises antimony trioxide. 56 A-S-Z 10 1.25 273 CPE 6. Method according to claim 4 wherein said com 57 Othe - 275 pound of antimony is an antimony-silico compound. 3,945,974 10 7. Method according to claim 4 wherein said com said compound of antimony is an antimony-silico com pound of antimony is a calcined complex of an antimo pound. ny-silico compound and zinc. 13. A smoke suppressing combustible polyvinyl 8. Method for forming a smoke suppressing combus chloride composition comprising a vinyl chloride poly tible polyvinyl chloride composition comprising adding mer having a smoke suppressant incorporated therein powdered zinc metal in combination with a flame retar said smoke suppressant comprising zinc dust added in dant to the components of said polyvinyl chloride com amounts in the range from about 0.2 to no more than position during formulation thereof said zinc metal about 1.0 part, calculated as zinc oxide, per 100 parts added in amounts in the range of from about 0.2 to no polymer resin. more than about 1.0 part calculated as zinc oxide per 10 14. A smoke suppressing combustible polyvinyl 100 parts polymer resin. chloride composition according to claim 13 wherein 9. A smoke suppressing combustible polyvinyl chlor said compound of antimony is an antimony-silico com ide composition comprising a vinyl chloride polymer, a pound. stabilizer, and a smoke suppressant said smoke sup 15. Method for forming a smoke suppressing com pressant comprising zinc oxide in an amount in the 15 bustible acrylonitrile-butadiene-styrene polymer con range of from about 0.2 to no more than about 1.0 part taining an organic halide flame retardant comprising: per 100 parts polymer resin. adding zinc oxide to the components of said polymer 10. A smoke suppressing combustible polyvinyl during formulation thereof said zinc oxide added in chloride composition according to claim 9 wherein said amounts in the range of from about 0.2 to no more than polymer composition includes a plastitizer and a flame 20 about 1.0 part per 100 parts polymer resin. retardant additive said additive comprising a com 16. Method for forming a smoke suppressing com pound of antimony. bustible polyester containing an organic halide flame 11. A smoke suppressing combustible polyvinyl retardant comprising: adding zinc oxide to the compo chloride composition according to claim 10 wherein nents of said polyester during formulation thereof said said compound of antimony is antimony trioxide. 25 zinc oxide added in amounts in the range of from about 12. A smoke suppressing combustible polyvinyl 0.2 to no more than about 1.0 part per 100 parts resin. chloride composition according to claim 10 wherein ck ck ck :k sk.