Document 4a851Nyq4MNJLzO02rJw6V8qR

Voi. 14 Vinyl Chloride Polymers (Introduction) 305 VINYL CHLORIDE POLYMERS Vinyl chloride polymers, containing the repeating unit --CH2CHC1--, include in addition to the homopolymer copolymers with such monomers as vinyl acetate, pro pylene, or vinylidenc chloride. The polymers are used in both flexible and rigid form as moldings, foams, fibers, and films and sheeting. They also form the basis of plastisols, or vinyl dispersions, used extensively as coatings and molded articles. The homopolymers and the polymers with minor amounts of a comonomer are collectively re ferred to as PVC or PVC-type polymers in the literature. Chlorinated poly (vinyl chloride) is also a material of considerable interest. Introduction................................... Polymerization........................ Copolymers.................................... Properties........................................ Compounding................................. Fabrication...................................... Applications.................................... Chlorinated poiy(vinyl chloride) Fibers............................................... 305 320 345 35S 304 434 452 460 4GS INTRODUCTION Hi&toi ier.l background...................................... Economic aspects........................... Monomer............. ........................................................... Bibliography........................................................................................ 305 307 313 320 Historical Background The first mention of poly(vinyl chloride) was in 1872 by Baumann (1) when he described the formation of a white powder by the action of sunlight on vinyl chloride contained in a sealed tube. He had no idea of the composition of the new product but his examination showed that it was unaffected by a wide range of solvents. The forma tion of a compound with the formula C2H3CI had been reported earlier in 1835 by Rcgnault (2), but, apart from these two references, there was no further interest in vinyl chloride for forty years. Renewed interest w'as brought about by the overcapacity which had arisen in Europe in the production of calcium carbide. The potential of acetylene as an illuminant had been greatly overestimated and this had led to the construction of many new carbide plants. This resulted in a substantial price drop in the early part of the twentieth century; in 1905 the price of calcium carbide was 2S per ton, but in 1909 it had dropped to 9. The position was particularly acute in Germany and it was here that an extensive research program wras set under way to investigate possible chemical uses of acetylene. In 1912, Klatte (3) of Griesheim-Elektron filed a patent claiming the manu facture of vinyl chloride monomer by the reaction between acetylene and hydrogen chloride in the presence of a mercuric chloride catalyst. The formation of the polymer by the action of ultraviolet radiation wras confirmed and in 1914 the use of organic peroxides as accelerators for the polymerization was known (4). At the same time work on vinyl halides was being carried out in Russia by Ostromislensky (5). The polymer was being used as an intermediate in an attempt to pro duce synthetic rubber by dehydrochlorinatiou, using alcoholic and aqueous potash. VAB.0001131040 * 318 Vinyl Chloride Polymers (Introduction) Table 10. Physical Properties of Vinyl Chloride Monomer molecular weight boiling point at 7G0 nun, C freezing point, C flash point, C liquid density, g/ml at --20C at -- 25C at -- 30C viscosity, cP at -10C at -- 20C at -- 30C at -- 40C surface tension, dyne/cm at -- 10C at -- 20C at --30C refractive index, n',5 vapor pressure, nun at 25 C at --13.37C at --55.8G at --73.9C at --87.5C at --109.4C specific heat of liquid, cal/g/C specific heat of vapor, cal/g/mole/C latent heat of vaporization, cal/g at 25C at -- 13.37C latent heat of fusion, cal/g critical temperature, C critical pressure, atm absolute entropy at 25C, eal/K/g-mole heat of formation, cal/g-mole dielectric constant at 10s Hz and 17.2C 02.501 -13.37 -153.79 -78 0.98343 0.99176 0.999SG 0.24S 0.274 0.303 0.340 20.88 22.27 23.87 1.39S 3000 760 100 30 10 a 1 ,0^ j 0.38 10.8-12.83 71.26 79.53 18 14 158.4 Sf 52.2 -'?(/ 61.68 9000 6.26 t and hydrogen chloride, whereas hydrocarbons such as butadiene may be present when cracking techniques are used. Handling and Safely Measures Handling of vinyl chloride presents certain hazards because it is normally gaseous at room temperature and forms explosive mixtures with air; the explosive limits are 4.0% by volume in air (lower explosive limit) and 22.0% by volume in air (upper ex plosive limit). When large leakages of liquid vinyl chloride occur, it is difficult to wash the area clear because the monomer floats on the water and the vapor, which is heavier than air, does not disperse readily. Thus fires involving vinyl chloride are difficult to extinguish using water alone and carbon dioxide or chemical-type fire ex tinguishers should be available. In high concentrations, the gaseous monomer has a sweet ethereal odor and pro duces anesthesia. Continual working in an atmosphere containing 500 ppm is con sidered sufficient to produce symptoms of drowsiness with an inability to concentrate. T Vol. 14 Vinyl Chloride Polymers (Introduction) 319 A detailed study using rats (31) has shown that repeated daily exposure to concentra tions of 2-5% of vinyl chloride causes no permanent damage. It has been confirmed from 5 minute exposures of human subjects to vinyl chloride in concentrations of up to 2.0% that a concentration of about 600 ppm is required to produce minimum effects of anesthesia under continuous exposure. Those affected by mild doses recover quickly when removed from the affected atmosphere but in the cases of more severe exposure, the administration of oxygen together with artificial respiration may be necessary if respiration is affected. The patient should be kept quiet and comfortably warm and special attention be given to those with uncertain heart action. In case of spillage, contaminated garments should be removed at once and the skin areas well washed with soapy water. If the skin is seriously affected, treatment as for frostbite should be given. A full account of all procedures to be used for handling vinyl chloride is given in Ref. 32. Vapor pressure psi psig cm Hg 800 600 A 400 200 Fig. 6, Vapor pressure of vinyl chloride (27-29). Points marked O are from lief. 2S; those marked are from Ref. 30. VAB.0001131042 V b. 320 Vinyl Chloride Polymers (Introduction) Bibliography 1. E. Baumann, Liebigs Ann. 163, 308 (1S72). 2. V. Regnault, Ann. Chttn. (Phys.) 58, 307 (1835). 3. Chemischc Fabrik Griesheim-EIcktron, Gcr. Pat, 278,249 (Oct. 11, 1912). 4. F. Klatte and A. Rollett (to Chemischc Fabrik Griesheim-Elektron), U.S. Pat, 1,241,738 (Oct. 2, 1917). 5. I. Ostromislenskv, Chon. Zcntralblatl 1, 1980 (1912). 6. E. W. Reid (to Carbide and Carbon Chemicals Corp.), U.S. Pat. 1,935,577 (Nov. 14, 1933). 7. A. Voss and E. Dickhauser (to I. G. Farbcnindu.strie A.G.), U.S. Pat. 2,012,177 (Aug. 20, 1935). S. W. E. Lawson (to E. I. du Pont de Nemours & Co., Inc.), U.S. Pat. 1,867,014 (July 12, 1932). 9. W. L. Semon (to B. F. Goodrich Co.), U.S. Pat. 2,188,396 (Jan. 30, 1940); see also U.S. Pat. 1,929,453 (Oct, 10, 1933). 10. H. Fikcntscher and C. Keuek (to I. G. Farbcninduslric A.G.), Gcr. Pat. 654,989 (Jan. 6, 193S). 11. Chem. Eng. News 48, 31 (Aug. 3, 1970). 12. M. J. R. Cantow in A. Stauden, cd., Kirk-Olhiner Encyclopedia of Chemical Technology, 2nd ed., Vol. 21, Intersciencc Publishers, a division of John Wiley & Sons, Inc., New York, 1970, pp. 369-412. 13. Chcm. Eng. News 47, 19 (Aug. 4, 1969). 14. SPEJ. 26 (12), 38 (1970). 15. Plastics World 29, 11 (Jan. 1971). 16. Japan Plastics Age 8, 2S (Nov. 1970). 17. I. B. Kotlyav, Plasl. Mas. p. 17 (Nov. 1967). 18. Chem. Eng. Nmvs 48, 47 (Oct, 19, 1970). 19. Chem. Week, p. 93 (Aug. 22, 1964). 20. European Chem. News, p, 27 (Aug. 21, 1964). 21. Imperial Chemical Industries of Australia and New Zealand, Fr. Pat. 1,330,367 (June 6, 1962). 22. European Chem. News, p. 35 (Sept. 27, 1963). 23. S. Gomi, Hydrocarbon Process. Petrol. Refiner 43 (11), 165 (1964). 24. Chem. Week, p. 59 (March 3, 1971). 25. P. G. Caudle, Chem. Ind., p. 1551 (Nov. 9, 1968). 26. G. A. Ilazuvaev and K. S. Minskcr, Zh. Obshch. Khim. 28, 983-991 (1958). 27. A. R. Borens, private communication. 28. J. Timmermans, Physico-Chemical Constants of Pure Organic Compounds, Elsevier Publishing Co., London, Vol. 1, 1950, p. 276; Vol. 2, 1965, p. 234. 29. E. R, Blout, W. P. Hohenstein, and II. Mark, Monomers, Intersciencc Publishing Co., Inc., New York, 1949. 30. Vinyl Chloride Monomer, bulletin, The Dow Chemical Co., 1954. 31. Industrial Hygiene J. 24, 265 (1963). 32. Chemical Safety Data Sheet SD-56, Manufacturing Chemists Association Inc. C. A. Brighton BP Chemicals International Ltd. POLYMERIZATION Bulk polymerization.......................................... 321 Effect of oxygen............................................................................................................................. 330 Solution polymerization................................................................................................................ 330 Chain transfer and molecular-weight control......................................................................... 332 Copolymerization........................................................................................................................... 334 Industrial manufacture................................................................................................................ 335 Bibliography................... 343 Since 1946 kinetic studies of the free-radical polymerization of vinyl chloride have been carried out by many workers (1-21). The field has recently been reviewed (23). The majority of the early detailed studies were carried out in bulk using dilatomctry to follow rates of polymerization. Dilatomctry (qv) affords a sensitive technique for