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3,252,929 United States Patent Office Patented May 24, 1966 2 been prepared by hydrolyzing triethyltin halides with 3,252,929 aqueous alkali and dehydrating the resulting product at HEAT AND LIGHT STABLE HALOGEN-CONTAIN NG RESNS STABLIZED BY TRALKYL TN elevated temperatures; it has also been produced by dis PROPOLATES tilling triethyltin hydroxide under reduced pressure, by Ferdinand C. Mieyer, St. Louis, Mo., assignor to Monsanto reacting silver oxide with S-methyl triethyltin or bis(tri Company, a corporation of Delaware ethyltin) sulfide, and by reacting triethyltin hydride with No Drawing. Filed Dec. 28, 1961, Ser. No. 162,925 metal oxides such as HgC), ZnO, Fe2O3, PbO, AS4O6, 13 Claims. (C. 260-23) VO5 and KMnO4. Bis(trihexyltin) oxide has been pre pared by shaking trihexyltin bromide with aqueous This invention relates to the stabilization of halogen O sodium hydroxide in ether. Bis(trioctyltin) oxide has containing resins against the deteriorating effects of heat been prepared in a similar manner by brominating tet and light. raooctyltin at -40° C., shaking the resulting trioctyltin Halogen-containing resin polymers are notoriously un bromide with aqueous 33% sodium hydroxide in ether, stable upon exposure to heat and ultraviolet light. This and drying the product after removal of the Solvent at instability is evidenced by the rapid discoloration and 15 100° C./12 mm. The higher bis(trialkyltin) oxide may Serious stiffening apparent after exposure to processing be prepared by similar methods. temperatures, and/or outdoor weathering. Moreover, The propiolic acid used in the reaction with the bis(tri this instability is sometime aggravated by the presence alkyltin) oxides to produce trialkyltin propiolates is a of plasticizers and other additives which are themselves well known, readily available material. prone to degradation. It is imperative then for the suc 20 The trialkyltin propiolates are prepared by directly re cessful use of these halogen-containing resin compositions, acting propiolic acid with the bis(trialkyltin) oxide in that the formulation must contain additives capable of the presence or absence of a solvent or diluent. If used, preventing this discoloration and loss of physical proper such solvent or diluent may be any non-reactive solvent ties which occurs during processing and/or exposure to or diluent such as the common aromatic solvents, e.g., outdoor conditions, particularly ultraviolet light effects. benzene, toluene, etc., and the aliphatic solvents, e.g., Accordingly, it is an object of this invention to provide hexane, cyclohexane, heptane, etc., as well as the aliphatic novel halogen-containing resin compositions having im halides such as methylene chloride, methylene bromide, proved heat and light stability properties. Another ob chloroform, carbon tetrachloride. The reaction generally ject of this invention is to provide a process for stabilizing may be conducted over a broad temperature range short halogen-containing resinous polymers against the adverse 30 of decomposition of the reactants and products, e.g. from effects of heat and light. Other objects will become ap about -40° C. to 150 C., although more preferred parent from the following description of the invention. temperatures range from about 0° C. to 100 C. Atmos According to this invention it has been found that the pheric pressure is generally sufficient but reduced or ele heat and light stability properties of halogen-containing vated pressures may be used. Reaction times vary de resin polymer compositions are substantially improved 3 5 pending upon the bis(trialkyltin) oxide being used and by incorporating therein a trialkyltin propiolate compound the extent of reaction desired. Generally, for efficient having from 1 to 18 carbon atoms in each alkyl radical use of reactants with reasonably good yields of product, bonded to the tin atom of the compound, in heat and the reactants are allowed to stand, or are shaken or stirred light stabilizing amounts. for time periods ranging from /2 to 10 hours, the shorter The trialkyltin propiolate compounds which are used as 40 time periods generally being used with the more vigorous heat and light stabilizers for halogen-containing resin physical reaction conditions. compositions in accordance with this invention are the Separation of the trialkyltin propiolate products from subject of a copending application S.N. 162,926, filed the reaction media may be accomplished by known December 28, 1961, and as described therein may be chemical and physical means. When the product is prepared by reacting propiolic acid with a bis(trialkyltin) liquid, distiliation or solvent extraction procedures are oxide. These trialkyltin propiolate compounds may be normally sufficient. Solid products may be separated by characterized as having a triple bond, and a trialkylstannic filtration, washings, recrystallization procedures, etc. group bonded through an oxygen atom to the carboxyl Further purification by selective solvent extraction, dis group of the propiolic acid. tillation, or by absorptive agents such as activated carbon Examples of trialkyltin propiolates which may be 50 or clays can precede the removal of the inert liquid or used to effect heat and light stabilization of halogen-con solvent. taining resin compositions in accordance with this in It has been found according to this invention that tri vention are exemplified by the following: trimethyltin pro alkyltin propiolates of the above defined type provide piolate, triethyltin propiolate, tri-n-propyltin propiolate, both heat and light stability characteristics to halogen triisopropyltin propiolate, tri-n-butyltin propiolate, triiso containing resin compositions but they are particularly butyltin propiolate, tripentyltin propiolate, triheptyltin pro useful as light stability additives since for Such purposes piolate, tridecyl propiolate, tridodecyltin propiolate, tri they have been found to be far superior to other related pentadecyltin propiolate, trioctadecyltin propiolate. Tri types of compounds. They may be used as the only alkyltin propiolate having mixed alkyl groups, that is, stabilizer for the halogen-containing resin but can be those having different alkyl groups bonded to the tin atom 60 combined with other ingredients in the resin composition. of the molecule may also be used within the scope of The following examples are illustrative of the inven this invention. For example, there may be used di tion but in no manner are to be construed as limitative methylethyltin propiolate or dibutyloctyltin propiolate. thereof. Mixtures of trialkyltin propiolates may also be used. The compositions and examples set forth below are The bis(trialkyltin) oxides, used in preparing the tri 65 prepared by mixing the halogen-containing resin with alkyltin propiolates, may be obtained by a variety of the indicated plasticizer, epoxy compound, stabilizer com methods. They may be formed by a direct or indirect pound and processing aid in the amounts set forth. In dehydration of trialkyltin hydroxides. They may also general, the several ingredients are mixed on differential be prepared by the oxidation of trialkyltin hydrides with speed rolls at a roll temperature of 160 C-170° C. to metal oxides. For example, bis(trimethyltin) oxide has 70 form a homogeneous composition which is removed from been prepared by treating trimethyltin hydroxide with the roll in the form of crude sheets. These crude sheets elemental sodium in benzene. Bis(triethyltin) oxide has are about 0.040 inch in thickness employing a molding 3,252,929 3 4. cycle of 1 minute at 160° C. The heat stability is deter carbon arcs known commercially as No. 70 solid carbons mined by heating the molded sheet at 170° C. The and No. 20 cored carbons, the combination being such light stability is determined after fadeometer exposure. that one full-length carbon, either cored or solid is used with a pair of opposite type carbons, cut to a size length EXAMPLE I 5 of 4 inches. The temperature within the Fadeometer was controlled by the circulation of sufficient air to produce Formulation (Parts by Weight).--------- A. B C a black panel temperature of 145-.5 F. The test panels in the Fadeometer made four complete revolutions Polyvinyl chloride (PVC).-------------- 100 100 00 Di(2-ethylhexyl) phthalate- 50 50 47 about the arc light per minute and were exposed to the Epoxidized Soy Bean Oil (G-62).--------------------------- 3 O arc light for a period of at least 1000 hours' actual ex Stabilizer--------------------- 1. 3 2 posure or until that time when pronounced discoloration Stearic Acid (Processing Aid) ---------- % % % or degradation of the test sample warrants the termina Compositions of the above types were formulated and tion of the test. compounded as follows: Below is a tabulation of the results obtained: The PVC homoploymer, plasticizers, and stabilizer(s) 15 Heat Stability Light Stability were weighed into a tared 250 ml. beaker in the above Stabilizer Formula- Minutes Hours to indicated proportional amounts so that the combined tion No. to failure failure in weights of the ingredients of the composition totaled a at 170° C. fadeometer maximum of 60 grams. The contents of the beaker was stirred until homogeneous mixture was obtained, and 20 Control (no stabilizer)---------------- 20 50 Commercial stabilizer A- SO 600 then removed from the beaker and placed into the rolls (dibutyltin dilaurate). B- 120 1,400 C- 140 1,400 of a 3' by 6' roll mill machine. The formulations A- 80 S00 were mixed for 5 minutes in the rolls at 165 C. and Tributyltin propiolate---- B- 100 2,700 then sheets of the milled composition were pressed out. C--------- 140 2,300 Small rectangular portions of the sheeted compositions 25 were cut out and attached to the Results Sheet for com The test results indicate that compositions compared parison with other portions which are removed from the using tributyltin propiolate as a stabilizer exhibited sub sheet after designated numbers of time units of heat and stantially the same heat stability characteristics as com light treatment. 30 positions prepared using dibutyltin dilaurate.