Document RjJ1DJKZyDq30407kGzLww3Yz

IASI tment of I and the n ation of dt during mixing I control mii is the aar. "ii issued initiation it weekly v paraii other mixers ssion of i i'i trined ' critical n mnded a lilood * plivgram ' a! the "nk on a were .'rounds '(erase nsider- a-vii ms m land re has Id5.?. ` d and 'g and -1 Tides 'raped - unntrarts ore. ill iallv 'ITS tO I `I leilol VINYL PLASTICS Their Dermatological and Chemical Aspects GEORGE E. [ MORRIS, M.D. BOSTON DURING the past 12 years there has been a fivefold increase in the number of dermatoses caused by the chemicals used in the manufacture of plastics.1 New plastics are being developed each year, and it is necessary that the industrial phy sician and dermatologist know the fundamentals of the chemistry of the different plastics, so that lie will lie able to judge correctly any case that comes to him for judgment concerning causal relationship with the work. The patient knows little about his job except that he uses "raw stock" or "over lay" decorative, that he "spreads vinyl onto doth" or that he "dips a plastic pencil into a solvent known as MKK." The examining physician should know what the chemical of the "raw stock" can he.- He should know something about the chemistry of tlie vinyls and should have a speaking acquaintance with such things as MEK (methylethyl ketone), TCP (tricresyl phosphate), DOP (dioctyl phosphate), etc. Plastics, in general, may be divided into five groups or classes: 1. Condensation 2. Vinyl (or polymerization) 3. Cellulose 4. Synthetic rubbers 5. Miscellaneous Polymerization resins may be divided into six groups: 1. Polyvinyl resins 2. Polyacrylate resins 3. Polyvinylidene resins 4. Polyethylene resins 5. Polystyrene resins 0. Coumarcne and indene resins Polymerization is the chemical union of two or more molecules of a substance to form a new compound without the elimination of a secondary compound. A monomer is a substance consisting of a single part; a dimer is a substance consisting of two parts, etc. In. Morris is Assistant Clinical Professor of Dermatology, Tufts College Medical School. 1. Morris, G. I'..: Condensation Plastics: Their Dermatological and Chemical Aspects. ^A. M. A. Arch. Ind. Hyg. 5:37-43 (Jan.) 1952. 535 4AJ,-f. Tj'reA Tetd ^ Oce^p ?: 535~53<j' T 20497001 536 INDUSTRIAL HYGIENE AND OCCUPATIONAL MEDICINE The polymerization resins are almost always compounded with other ingredients to produce the finished plastics. Compounding ingredients include plasticizers, stabi lizers, pigments and dyes, lubricants, and fillers. POLYVINYL RESINS 2 Vinyl resins contain the vinyl linkage, -- CH2 = CHX. X must be a strongly negative group--chloride, acetate, butyrate, alcohol, or acetal. Vinyl chloride monomer CH = CH Acetylene + CH. = CHC1 + I Heat Pressure--Catalyst Copolymers HCI Hydrochloric acid CH,= CHC1 Vinyl chloride CH,-- CH -- CH,-- CH -- I I Cl Cl -CH,--CH -- I Cl Vinyl chloride polymer CH, = CHC1 CHj = CHOCOCHj Vinyl chloride 80-9S7<, Vinyl acetate 2-20% -- CHa CH -- CHi- - CH -- CHj -- CH -- CH, -- CH -- CH, 1 !I ! Cl Cl O-C-- O-CH, Cl Dermatitis in a coaler of vinyl plastics. The more vinyl acetate that is used, the more soluble is the product and so the more useful for coatings (see "Flow Chart"). The trade names include Vinylite, (jeon, Koroseal, Satlex, Marvinol, etc. They are used as moulding compounds, adhe sives, fabrics, cable coverings, floor tile, belts, raincoats, toys, etc. I have not seen any eruption from the finished product, but the Figure shows an eruption from vinyl latex used for coating artificial leather. 2. Shrove, R. X.: Chemical Process Industries, New York, McGraw-Hill Book Company, Inc., 1945. Polyacrylai derivatives: CH,= < CH,= t CH,= I CH, = i Methyl Acryla CH, CN-- CH Ethylene c\ The polyn ( The trade coatings, leath Only a fe\ Monon Polymeriz It is often vinyl chloride The trade na covers, pipe, Cracked pc o 03 The trade na of blown boi O cable insula! MORRIS--VINYL PLASTICS 537 POLYACRYLATE resins Polyacrylate resins are formed from the polymerization of acrylic acid and its derivatives: CHi = CHCOOH CH==CHCOOCH, CH,= C(CH,)COOH CH, = C( CH,) COOCH, Acrylic acid Methyl acrylate Mcthacrylic acid Methyl methacrylate Methyl Acrylate Polymerization Cracking Petroleum------ process CH, = CH, Ethylene H:0 CH, = CH= -------------------- Cl CHjCL CHaOH -1- NaCN --* Ethylene chlorohydrin catalyst CH, CN-- CH,OH 4- CH3OH---------------------------------> CH.CHOCOCH, Ethylene cyanohydrin Methanol The jtolvmer is --CH* --CI-I -- [CH,--CH),,, -- CH, --CH / 0 = C --OCH, !( O --C -- OCH, O --C--OCH, The trade names are Plexiglas and Lucite. They are used as dentures, adhesives, coatings, leather finishes, optical novelties, etc. Only a few cases of stomatitis have been seen from acrylic dental plates. POLYVINYLIDENE RESINS Monomer--vinylidene chloride Clh = C CH Polymerizes Cl Cl Cl --CH, -- C -- CH, -- C -- I Cl Cl CH, --C -- Cl It is often copolymerized with vinyl chloride (10% vinylidene chloride and 90% vinyl chloride). . H HC11 -- CHCt111 I -- H|1c Ii i -- CCclII11! -- Hc1111 H -- CCC1111 ll -- IC111!I H -- CCc11!1 ll -- Hi1 1c ! H -- CC111I l H -- . The trade name is Saran. It is used in the manufacture of upholstery fabrics, seat covers, pipe, tubes, battery cases, belts, suspenders, etc. POLYETHYLENE RESt NS Cracked petroleum Heat CH,= CH,---------------------- Ethylene Pressure r HHHH --C-C--C--C-- H H H H J.i Polyethylene The trade names are Polythene and DYNF Resin. The resins are used in the form of blown bottles, tubing, tape, sheeting, film, and for packaging, tableware, wire and cable insulation, molded closures, etc. O ** co V % & 1 538 INDUSTRIAL HYGIENE AND OCCUPATIONAL MEDICINE Occasional sensitization to these resins occurs, especially in workers coating the resins before complete polymerization has occurred. Styrene POLYSTYRENE RESINS i-CH^CH, . E.hylm, Ethyl 1-CH-CH. + H, Polymerizes as follows: -CH,- (JH-CHj'CH-CHj-CH- The trade names are Lnstron, Lnstrex, Polystyrene, Styramic and Plexene. They are used as bottles, jars, closures, tableware, toilet articles, wall tile, brushes, etc. COUMARONE AND INDENE RESINS These are coal tar derivatives. 1 CH, The polymerization is similar to that of styrene. The trade names are Cumar, Nevillac, and Nypene. These are used for coatings, varnishes, printing inks, tile, rubber compounding, and chewing gum. 'J'he compounds added to the resins include plasticizers, stabilizers, lubricants, colorants and fillers. Plasticizers are chemicals which render the finished product more plastic. They make up 10% to 50% of the weight of the finished product. They include the follow ing: phosphates (tricresyl phosphate--TCP) ; phthalates (dioctyl phthalate-- DOP) ; ricinoleic acid derivatives; sebacic acid derivatives; azelates; polyesters; nitrile rubbers; petroleum derivatives; chlorinated aromatic hydrocarbons. Stabilizers are substances which prevent decomposition from heat and sunlight. They make up 2 to 5% by weight. They include lead compounds (basic white lead carbonate and basic white lead silicate) ; tin compounds, epoxides, phosphates, and metallic soaps. Lubricants are added to plastics and make for ease of flow (internal and exter nal). They include fatty acids, waxes, oils, and metallic soaps. The colors used include dyes and pigments. Fillers are added to confer chemical resistance, mechanical strength, electrical properties, and thermal resistance. The mineral fillers are commonly used and include clays, mica, asbestos, limestone, and diatomaceous earth. T Vinyl A and H may D may CH, -- CJ CH,--C--(( CH, CO CH, cc: The pi. for shipnn tization d< c w* O o `"g < They cs. etc. N'evil- libber Cants, They follow 'd ate-- esters; 'Tight, he lead es. and cxters used ectrical d and MO KRIS--l'IN YL PLASTICS 539 SUMMARY Vinyl resins are formed hy the polymerization of BH II A--C=C--D------------------ BH r -c-c- 1I AD BH II C--C I1 AD AH .I I -C--C-- I! BD A and B are preferably hydrogen, occasionally FI or Cl. H may he hydrogen, Cl, F, CN, or CH:t. D may be hydrogen or COOH, Cl, F, CN, COOR, CH5, -- O--R, -- CH:i. CH, -- CH CH,--C--(CH,) CH, at. CCX CC1 H C.H* Cl OR O COCH, F COOH CN COOH COOCH, CN Cl CN Ethylene Styrene Vinyl chloride Vinyl ether Vinyl acetate Vinyl fluoride Acrylic acid Acrylonitrile Methacrylic acid Methyl methacrylate Vjnylidene cyanide Vinyl idene chloride Chloroacrylonitrile The polymerization resins are handled by enclosed processes until they are ready for shipment. Workers handling the partially polymerized resins may develop sensi tization dermatitis. Eruptions caused by the finished products are rare but do occur.