Flame retardant vinyl chloride polymers containing zinc zirconate
United States Patent 1 1 Dickens, Jr.  
 [451 Apr. 29, 1975 FLAME RETARDANT VINYL CHLORIDE POLYMERS CONTAINING ZINC ZIRCONATE Appl. No.: 493,723  
 Inventor:  
 Assignee:  
 US. Cl 260/45.75 W; 260/4575 F;  
  260/4249 Int. Cl. C08f 45/56 Field of Search 260/4575 W; 106/15 FP;  
 References Cited UNITED STATES PATENTS Cox 260/4575 Riches 117/138 Elliott..... 260/45.75 Scullin 260/4575 Yates 260/4249 Primary ExaminerV. P. Hoke Attorney, Agent, or Firm-J. Hughes Powell, Jr.  
 ABSTRACT Vinyl chloride polymers are compounded with zinc zirconate to provide improved flame resistance and reduce smoke production.  
 4 Claims, No Drawings FLAME RETARDANT VINYL CHLORIDE POLYMERS CONTAINING ZINC ZIRCONATE BACKGROUND OF THE INVENTION Presently there is a pressing need for improved plastic products which are safer in fire situations,.even for vinyl chloride polymers which generally are considered to be flame resistant. While rigid vinyl chloride products have many structural applications useful in build- 2 group such as vinylidene chloride, alkyl acrylates and methacrylates wherein the alkyl group contains one to 10 carbon atoms, acrylic acids, amides and nitriles thereof such as acrylic acid, ethacrylic acid, acrylam- 5 ides, N-methylol methacrylamide, acrylonitrile, methacrylonitrile and the like, alphaolefins containing two to six carbon atoms such as ethylene and propylene, vinyl esters such as vinyl acetate. vinyl butyrate, vinyl benzoate, vinyl aromatics such as styrene, chlorostyrene, ethyl styrene, vinyl naphthalene, vinyl alkyl ethers, vinyl ketones, chlorinated vinyl chloride polymers; and blends of vinyl chloride polymers with other polymers, both plastics and elastomers, for example, with ABS resins, with l to 40 percent of copolymers of styrene and acrylonitrile or styrene and methyl methacrylate wherein styrene is the major component,  
 elastomers containing about equal amounts of styrene and acrylonitrile with butadiene, polyurethanes, nitrile &#34;elastomers, both liquid and solid containing from about 15 to 40 percent acrylonitrile with the remainder butadiene, polyolefins and the like. These vinyl chloride flame spread. While a number of materials have been proposed and used in vinyl chloride for this purpose,  
 very few have been found to be completely satisfactory. Many are not compatible or readily mixed with vinyl chloride polymers, many are colored or form colored products in vinyl chloride polymer compositions and many have adverse effects on the physical properties of vinyl chloride polymers.  
 SUMMARY OF THE INVENTION Zinc zirconate is a very effective fire and smoke retardant in vinyl chloride polymer compositions even in low concentrations. The zinc zirconate is compatible and easily mixed with vinyl chloride polymers in both rigid and flexible forms, has low tinting power, does not form objectionable color products in vinyl chloride polymers and has no adverse effects on the physical properties or processing of compounds containing it.  
 DETAILED DESCRIPTION The zinc zirconate is normally used in powder form.  
 in amounts greater than about 0.01 part per 100 weight parts of vinyl chloride polymer, more preferably from about 0.1 to about to weight parts per 100 weight parts of vinyl chloride polymer. From about 0.25 to about 3 weight parts is a very practical range providing -a good balance of desirable properties in the compounds. The zinc zirconate is readily mixed with the vinyl chloride polymers in powder form as is any other powder ingredient mixed with vinyl chloride polymers as is well known to those skilled in the art.  
  The vinyl chloride polymers include those vinyl chloride polymers that are homopolymers, that is, polyvinyl chloride, as well as those copolymers containing vinyl chloride and up to about 50 percent, more usually about percent by weight of at least one other vinylidene monomer containing at least one terminal polymers normally are high molecular weight polymers having a specific viscosity greater than 0.4 measured as a 0.4 percent solution in nitrobenzene.  
  The vinyl chloride polymers will be mixed with standard compounding ingredients known to those skilled in the art, plasticizers, lubricants, stabilizers, fillers, colorants, processing aids, other flame and smoke retardants, and the like. While these compounds are most effective in vinyl chloride polymers substantially free of plasticizers subject to burning, they provide improved compositions as to flame propagation and smoke when plasticizers are present.  
  In the following Examples, there is reported the oxygen index, OI, a D smoke rating, and D,,,, a maximum optical density observed with a vertical light path in the National Bureau of Smoke Chamber (NBS). The oxygen index is determined in accordance with ASTM D2863 test method and D&#39; smoke number measured when this apparatus is modified by the means described by Dipietro et al., Journal of Flame and Flammability, Volume 2, Page 36, 197 l i.e., the optical density of the smoke generated when the sample is burning at the rate of 0.6 gram/minute; The NBS smoke chamber and its use are described by Gross et al. in fire test methods ASTM STP 422, 1967, Pages 166-206. The NBS D smoke numbers reported are in the flaming mode.  
 EXAMPLE I A vinyl chloride polymer compound was prepared by mixing weight parts of polyvinyl chloride, Geon x233, specific viscosity of 0.38 0.42 percent in nitrobenzene at 30C., with 2 weight parts of polyethylene having a specificgravity of 0.924 g/cc and melt index of 5 g/ 10 minutes, and the amounts of zinc compound shown in the data table below. The ingredients were all dry blended, milled at 330F. for 5 minutes, press molded at 350F. for 8 minutes at 320F. 6 X 0.25 X 0.075 inch test samples were used for the oxygen Index and SmokeOI. 2 /8 X 2 X 0.05 inch test samples were used for the NBS smoke chamber and the char test was on A X A X 0.075 inch or dry pressed A X 5 X 0.280 inch pellets. A one minute burn was used.  
 TABLE I Zinc Salt in Oxygen 7c (phr) Recipe Index D&#39;., D,,, Char&#34; TC&#34; None 42 550 630 2 5 Zn ZrO 1/2) .24 49 160 14.8 34  
  (2) .95 60 140 378 16.5 37 zn P O, (1/2) .22 38 755 2.7 6  
  (2) .84 43 685 5.2 12 ZnTiO (1/2) .18 66 145 381:45 13.2 30  
 (a) D&#39; is the smoke rating for the Smoke-O1 test.  
 (h) D,,, is the smoke rating for the NBS Smoke Chamber test. All numbers are based on an average of duplicate runs. Sample thickness was normalized to 50 mils.  
 (cl &#39;4 Char M,-M,/Ni X 100. where M,= initial wt.. M,= final wt. Samples were exposed to a propane torch for 1.0 minute. Sample geometry was 1/4&#34; X 3.4&#34; X 0.075&#34;. Average of two runs.  
 (d) &#39;/1 TC Z of theoretical char &#39;4 Char/A. where A is the maximum amount of char that can he formed and is defined by A .44/l()(l+X X/l(ll)+X. X phr additive.  
 (e) Pressed sample after test was black. That containing Zn ZrO was amhcr.  
  In a pigmented plasticized formulation containing 34 3. A composition of claim 1 wherein the vinyl chlopercent of B SO pigment and 18 percent of dioctyl ride polymer contains up to about 50 percent by weight phthalate plasticizer with 2 parts of zinc zirconate there 20 of at least one vinylidene compound copolymerized is less smoke produced as compared to the control. therewith having a terminal 1 claim: 1. A composition comprising a vinyl chloride poly- CH =C mer and zinc zirconate in an amount of from about group. 0.01 to about 10 weight parts per 100 weight parts of 4. A composition of claim 2 wherein there 15 0.75 to vinyl chloride polymer. 3 parts of zinc zirconate.  
  2. A composition of claim 1 wherein the vinyl chloride polymer is poly(vinyl chloride).