United States Patent (19) (11) E Patent Number: Re. 32,935 Larkin (45) Reissued Date of Patent: May 30, 1989 (54) NON-TOXIC ORGANOTIN STABILIZERS FOR WNYL CHLORIDE POLYMERS FOREIGN PATENT DOCUMENTS 869588 4/1971 Canada . 75 Inventor: William A. Larkin, Avon-by-the-Sea, 6896 2/1972 Japan. N.J. 7639 4/1972 Japan. 39570 10/1972 Japan. (73) Assignee: M&T Chemicals, Inc., Rahway, N.J. 1326057 8/1973 United Kingdom . (21) Appl. No.: 798,637 1349913 10/1974 United Kingdom . 22) Filed: Nov. 15, 1985 OTHER PUBLICATIONS Arch. Toxikol 26 196-202 (1970). Related U.S. Patent Documents Plaste & Kantschuk 19, (5), pp. 325-336 (1972). Reissue of: Fortschritte der Chemischen Forschung 16 (3/4), pp. (64) Patent No.: 4,496,490 393-403 (1971). Issued: Jan. 29, 1985 Neumann, The Organic Chemistry of Tin, John Wiley Appl. No.: 120,753 & Sons, Intersc. Publ., N.Y., pp. 230-237; 240-242 Filed: Feb. 12, 1980 (1970). Bokranz et al, Fortschritte der Chemischen Forschung, U.S. Applications: vol. 16, Nos. 3-4, pp. 365 and 398-404 (1971). (60) Continuation-in-part of Ser. No. 43,997, May 31, 1979, abandoned, which is a continuation of Ser. No. Primary Examiner-Curtis R. Davis 454,363, Mar. 25, 1974, abandoned, which is a division Attorney, Agent, or Firm-Burns, Doane, Swecker & of Ser. No. 343,648, Mar. 22, 1973, abandoned. Mathis (51) Int. Cl." ......................... B65D 85/00; CO7F 7/22 (57) ABSTRACT (52) U.S. C. .................................... 426/106; 426/131; Vinyl chloride polymers suitable for use in food packag 426/415; 556/93; 556/96; 556/97; 556/102 ing materials are stabilized against discoloration and 58 Field of Search ..................... 556/93, 96, 97, 102; embrittlement resulting from exposure to heat using 426/106, 131, 415 mono-n-octyltin compounds of the general formula (56) References Cited H17C3Sn(SCH2COOR")3, wherein R' represents an alkyl radical containing eight carbon atoms. U.S. PATENT DOCUMENTS 3,657,294 4/1972 Glaskey ............................ 556/88 X 17 Claims, No Drawings Re. 32,935 1. 2 octyltin trichloride and tri-n-octyltin chloride. The NON-TOXC ORGANOTIN STABLIZERS FOR inorganic tin compounds that may also be present in WNYL CHLORIDE POLYMERS clude stannic chloride and stannous chloride. Both of these compounds exhibit relatively little, if any, toxic Matter enclosed in heavy brackets appears in the ity. The organotin compounds which are often present original patent but forms no part of this reissue specifica as impurities allegedly increase the toxicity of the resul tion; matter printed in italics indicates the additions made tant di-n-octyltin oxide, which is subsequently em by reissue. ployed as a starting material for the preparation of low toxicity stabilizers for vinyl chloride polymers. U.S. BACKGROUND OF THE INVENTION Pat. No. 3,640,947, issued to C. R. Gloskey, discloses This application is a continuation-in-part of Applica that a mixture of octyltin oxides employed to prepare a tion Ser. No. 043,997, filed May 31, 1979, now aban non-toxic octyltin stabilizer composition contains not doned, which in turn is a continuation of Application more than 5% by wieght of mono-n-octylstannoic acid, Ser. No. 454,363, filed Mar. 25, 1974, now abandoned, the precursor of n-octyltin-S,S,S'-tris(isooctyl mercap which in turn is a divisional of Application Ser. No. 15 toacetate). The final stabilizer is obtained by reacting 343,648, filed Mar. 22, 1973, now abandoned. the mixture of n-octyltin oxides with isooctyl mercapto The present invention concerns non-toxic organotin acetate. Had either Katsumura et al. or Gloskey recog stabilizers. More particularly, this invention relates to nized that mono-n-octyltin-S,S,S'-tris (isooctyl mer liquid organotin stabilizer compositions that are suffi captoacetate) was equally low in toxicity as the corre ciently low in toxicity to be suitable for use with halo sponding di-n-octyltin compound there would be no gen-containing polymers that are employed as food reason to limit the concentration of the mono-n-octyltin packaging and handling materials and beverage con compound. tainers. Available data concerning the relative toxicities of Polyvinyl chloride and other halogen-containing mono-, di- and trialkyltin compounds containing the polymers are inherently unstable when exposed to tem 25 same alkyl group are contradictory. For example, W. P. peratures above about 100 C. for the extended periods of time required for melt processing and shaping. A Neumann, in a text entitled "The Organic Chemistry of variety of compounds effectively prevent or delay the Tin' discloses that "(f) or the same alkyl group, maxi discoloration and embrittlement exhibited by vinyl mum toxicity is found in the compound of type R3SnX, chloride polymers at these temperatures. The increasing 30 followed by R2SnX2 and R4Sn. RSnX3 is the least toxic use of vinyl chloride polymers as food packaging mate or non-toxic'. In the same chapter Neumann presents a rials in the form of films, bottles, pipes, trays and other table of acute toxicity values determined by force-feed containers has been made possible by the development ing relatively large amounts of the test chemical to rats. of stabilizers which inhibit heat-induced discoloration The lethal dose for the population, referred to as and decomposition of the polymer, yet are of suffi 35 LD50, is greater than 6,000 mg per kilogram of body ciently low toxicity for use in materials that are in weight for tri-n-octyltin laurate and bis(tri-n-octyltin) contact with food and beverages. sulfate. By comparison, the LD50 values for the di-n- Organotin compounds have long been recognized as octyltin compounds reported ranges from 1975 for di-n- one of the most effective stabilizers for vinyl chloride octyltin-S,S'-bis(isooctyl thioglycollate), referred to as homopolymers and copolymers. U.S. Pat. No. 2,789,963 di-n-octyltin-S,S'-bis(isooctyl mercaptoacetate) in the discloses a variety of organotin compounds that are aforementioned Gloskey patent, to 4,500 for di-n-octyl suitable for this purpose. Diorganotin dimercaptides tin maleate. It is evident from these data that the diooc and bis(mercaptocarboxylic acid esters) are particularly tyltin compounds are from 1.3 to 3 times more toxic preferred classes of stabilizers. A shortcoming of many than two tri ooctylin compounds. The toxicity data of these organotin compounds, which can be repre 45 reported by Neumann are not the result of work per sented by the general formulae R2Sn(SR")2 and formed by the author, but rather the data are collected from articles by recognized toxicologists, including O. O R. Klimmer. The relative toxicity data discussed in the A. preceding section of this paragraph are taken from a 50 lecture given by Professor Klimmer at the Organotin OR Symposium at Frankfurt during November of 1963. Klimmer and J. G. A. Luijter, a recognized expert on wherein R and R represent monovalent hydrocarbon the subject of organotin chemistry, are coauthors of a radicals and R' represents a divalent hydrocarbon radi paper that was presented at a conference in Dusseldorf cal, is that they are too toxic for use in food packaging 55 on Nov. 15, 1973. The conference was sponsored by the materials. It has been reported by Katsumura et al. in Tin Information Bureau, GmbH. In their paper Klim U.S. Pat. No. 3,390,159 that di-n-octyltin derivatives are mer and Luitjen report that the acute oral toxicity of considerably less toxic than other organotin stabilizers monooctyltin trichloride is greater than the toxicity of for polyvinyl chloride. At present only one member of either dioctyltin dichloride or trioctyltin chloride. this class of compounds, di-n-octyltin-S,S'-bis(isooctyl These data, when considered in combination with the mercaptoacetate) has been approved by the United aforementioned U.S. Pat. No. 3,640,947, which limits States Food and Drug Administration for use as a stabi the combined maximum concentrations of the corre lizer in food packaging materials. The aforementioned sponding mono- and tri-n-octyltin compounds in a di-n- U.S. Pat. No. 3,390,159 is concerned with a process for octyltin oxide composition employed to prepare a non preparing di-n-octyltin oxide from the corresponding 65 toxic stabilizer to 5% by weight of the di-n-octyltin di-n-octyltin dichloride in the absence of impurities. compound, indicate that n-octyltin-S,S,S'-tris(isooctyl These impurities result from the presence in the crude mercaptoacetate) would be more toxic than the stabi di-n-octyltin dichloride of significant amounts of n lizer composition of the Gloskey patent. This is con Re: 32,935 3 4. trary to the aforementioned general statement by Neu toxicities of the ingredients of the plastics as expressed mann concerning the relative toxicities of mono-, di by their Toxicity Factors to give the Toxicity Quotient, and trialkyltin compounds. which is the measure of the hazard. Actute toxicity values are determined by force-feed It should be evident from this discussion that the ing relatively large doses of the test compound to a 5 general statement "octyltin compounds are lower in group of rats or other animals and determining the toxicity than the corresponding lower alkyltin com concentration level which is lethal to a certain percent pounds' cannot be taken as an assurance that any octyl age of the population. While these data may be useful tin compound is a potential food grade stabilizer in the for certain applications of organotin compounds, they absence of chronic toxicity and extractability data. are insufficient to ascertain whether a given organotin O The only prior art references disclosing monooctyltin compound is sufficiently low in toxicity for use in mate compounds mention these compounds and the corre rials which come in contact with food.