United States Patent (19) (11) 4,439,572 Kindrick 45 Mar. 27, 1984 (54) ZINCOXIDE-ZINCSALT SMOKE 58) Field of Search ..................... 106/18.27; 524/399, SUPPRESSANT/FLAME RETARDANTS 524/405, 411, 417,420, 423, 432, 434, 472; 75) Inventor: Robert H. Kindrick, Grosse Ile, 523/210, 200, 205, 223 Mich. 56 References Cited (73) Assignee: The Sherwin-Williams Company, U.S. PATENT DOCUMENTS Cleveland, Ohio 2,785,990 3/1957 Coulter ....... 106/296 3,900,441 8/1975 King ... ... 524/406 (21) Appl. No.: 443,723 3,945,974 3/1976 Schwarcz et al. ... S24/409 3,957,723 5/1976 Lawson et al. ..................... 524/432 (22) Filed: Nov. 22, 1982 4,111,885 9/1978 Abu-Isa ............................... 524/405 Primary Examiner-Melvyn I. Marquis Attorney, Agent, or Firm-James W. Tura; Robert E. Related U.S. Application Data McDonald 63) Continuation-in-part of Ser. No. 315,336, Oct. 26, 1981, abandoned. 57 ABSTRACT This invention is directed to halogen-containing poly (51) Int. Cli................................................ CO8K 3/38 meric compositions containing a smoke suppressant/- (52) U.S.C. .................................... 524/405; 524/399; flame retardant comprising intimate mixtures of zinc 524/411; 524/417; 524/420; 524/423; 524/432; oxide and zinc salts. 524/434; 524/472; 523/200; 523/210; 523/205; 523/223; 106/18.27 13 Claims, No Drawings 4,439,572 1. 2 zinc oxide could be used to reduce cost at least as a ZINCOXIDE-ZINC SALT SMOKE partial if not a total replacement for these flame retar SUPPRESSANT/FLAME RETARDANTS dants or smoke suppressants, e.g. molybdum oxides, zinc borates, antimony oxides, etc. This application is a continuation in part of applica tion Ser. No. 315,336 filed on Oct. 26, 1981 now aban SUMMARY doned. This invention relates to a process of utilizing a mix ture of zinc oxide and zinc salts of certain acids as addi BACKGROUND OF THE INVENTION tives for halogen-containing polymeric compositions This invention relates to polymeric compositions and 10 which afford all of the advantages achieved by using specifically to smoke suppressant/flame retardant addi. zinc oxide alone and has improved smoke and fire re tives for polymeric compositions comprising halogen tardancy and avoids the problems known as zinc failure containing polymers. More, specifically, this invention in chlorinated polymers. In accordance with this inven relates to a method of improving the flame and smoke tion, zinc oxide is slurried with certain acids, e.g. phos suppressing characteristics of halogen-containing poly 15 phoric acid to produce an intimate mixture of zinc oxide meric compositions by adding to said compositions and the zinc salt of such acid wherein the zinc oxide is effective amounts of at least one inhibitor "consisting present in the mixture in amounts, ranging from 50 to essentially of an intimate mixture of zinc oxide and zinc 95% by weight and the zinc salt is present in amounts salts, i.e. zinc borate, zinc phosphate or zinc sulfide. ranging from 5 to 50% by weight of the mixture. Polymeric compositions comprising halogen-contain 20 Various polymeric compositions and particularly ing polymers used for sheeting, synthetic fibers and the polyvinyl chloride, polyvinylidine chloride, and the like are hazardous due to flammability and it is well polyolefins such as polyethylene and polypropylene known to incorporate within these polymeric composi with halogenated materials can have the flame and tions certain flame retardants and/or smoke suppres smoke suppressing characteristics' improved by incor sants to reduce both the flammability and smoke: More 25 porating therein small but effective amounts of at least over, these polymeric compositions are known to create one, inhibitor of this, invention. The inhibitor consists large amounts of smoke during burning which is more essentially of an intimate mixture of zinc oxide and at hazardous then the flame. Thus, there is increased con least one zinc salt selected from the group consisting of cern for safety due to the fact that smoke, evolution zinc, phosphate, and zinc sulfide wherein the zinc salt during the burning of these plastics is as much a hazard 30 ranges from about 5 to 50% by weight of the mixture. if not more than the flames. Certain additives can be Small but effective amounts of the zinc oxide mixture is used to avoid the hazards due to smoke and toxic gases. added to the halogen-containing polymeric composi These additives include, for example, antimony oxide tions, i.e. an inhibitor amount ranging from about 1.5 to either alone or in combination with other compounds 10% and preferrably from 3 to 7% by weight of the known to suppress both flame and smoke in halogen 35 halogenated polymeric materials. In addition, other containing compositions. known inhibitors such as antimony oxide may be added Accordingly, it is an object of this invention to pro to the polymeric compositions in combination with the vide a smoke suppressant and flame retardant for halo mixture of zinc oxide and zinc salts. These other inhibi gen-containing polymeric compositions comprising an tors may be added to the halogen-containing polymeric intimate mixture of zinc oxide and certain metal salts of 40 compositions in amounts ranging from 1.5 to 5.0% by zinc which are more effective than either one of the weight of the polymers in addition to the zinc oxide and components alone. Zinc oxide alone has not been found zinc, salts. - useful as a smoke suppressant or flame retardant partic It is therefore an object of this invention to provide a ularly in polyvinyl chloride in that it causes rapid degra process whereby zinc oxide is modified by converting a dation during processing. For example, trace amounts 45 portion thereof to the zinc salt of the acid, e.g. phos of hydrochloric acid in these polymeric resins converts phoric acid, or sulfuric acid to provide an intimate mix the zinc oxide to the chloride which catalyzes the dehy ture of the oxide and zinc salt of such acid to improve drochlorination of the resin resulting in a phenomenon the flame retardancy and smoke suppressant character known as zinc failure. Zinc failure manifests itself by the istics of the compositions. Thus, these zinc oxide salt appearance of black spots in the plastic film. Continual 50 mixtures can be used as a total replacement or at least a degradation results in the loss of hydrochloric acid and partial replacement of other additives and thereby finally the total destruction of the polymer. To avoid avoid the problem of zinc failure, etc. which generally these problems, various stabilizers have been used in occurs in chlorinated polymeric compositions. It is cluding, for example, the use of barium or cadium salts another object of this invention to provide an intimate such as the stearates to prevent or at least delay zinc 55 mixture of zinc oxide and zinc salts which are compara failure. However, these stabilizers alone are generally tively lower in cost then other known flame and smoke not sufficient to avoid the potentially danger of dehy suppressants. drochlorination when the polymeric materials are used in high pressure equipment such as extruders, injection DETAILED DESCRIPTION molding machines and the like. The zinc salt/zinc oxide mixtures characterized as Moreover, zinc oxide alone is not recommended as a zinc oxide coated with the zinc salts are prepared by polymeric additive since in certain flame tests zinc slurrying zinc oxide in a dilute solution of the acid to oxide appeared to be too reactive. In some instances, the form the corresponding salt on the surface thereof. In flames were found to spread in formulations utilizing accordance with this invention, the zinc oxide is coated zinc oxide and in some cases worse then the control 65 by the 'salt formed in situ with the acid resulting in a which had no fire retardant present in the formula. product which is primarily zinc oxide coated with the Moreover, other commercially available additives are zinc salt. More specifically, in accordance with this more costly and therefore it would be an advantage if invention a zinc phosphate coated zinc oxide was pre 4,439,572 3 4. pared in an exothermic reaction, when particulate zinc able zinc borate product. In all examples, the stability of oxide was slurried in approximately a 10% solution of the polymer was comparable or better than the com orthophosphoric acid while stirring at temperatures mercial product. ranging from about 60 to 80 C. The filtered and dried product comprised from about 50 to 95% by weight of 5 EXAMPLE II zinc oxide with a coating ranging from about 5 to 50% Zinc phosphate-coated zinc oxide containing 10, 20 of zinc orthophosphate. and 30% by weight zinc phosphate were tested in a Similarly, zinc oxide coated zinc sulfide product was PVC formulation plasticized only with DOP which is prepared by dispersing sodium acid sulfide or H2S in a O especially sensitive to zinc failure. The formulation dilute 10% (sulfuric acid solution) wherein zinc oxide is comprised 100 parts PVC resin (Conoco 5385), 50 phr slurried. After standing over night, the filtered, washed DOP, 7.5 phr epoxidized soy bean oil, 0.8 phr and dried slurry resulted in a product that was about Ba/Cd/Zb stabilizer (Mark KCB, Argus), 2 phr anti 30% by weight zinc sulfide present as a coating on the mony oxide and 4 phr of the 10, 20 and 30% ZnO/ZnP surface of the zinc oxide. coated zinc coated zinc oxide mixture. The results of The following examples illustrate the use of zinc the Rheocord stability test and Arapahoe percent oxide/zinc salt mixtures in various rigid and flexible halogen-containing polymeric compositions.