19. RAW MATERIALS FOR VINYL RESINS
Vinyl resins are made chiefly from vinyl acetate and vinyl chloride.
Vinyl acetate is an unsaturated ester of the hypothetical vinyl alcohol. It is made from acetylene and acetic acid, and is a colorless liquid with a pleasant sweetish odor, boiling at 73° C. On account of its tendency to polymerize to polyvinyl acetate, a trace of copper salt is added for shipment. To render the vinyl acetate chemically active again, the copper salt is removed by distillation. At present the sole use of vinyl acetate is for the manufacture of synthetic resins. (See pp.43-50.)
Vinyl chloride, a salt of vinyl alcohol, is obtained commercially from acetylene. It is a gas (boiling at about minus 14° C.) used in the manufacture of synthetic resins. Vinyl chloride mixed with vinyl acetate is polymerized to a synthetic resin.
Until 1938 the one domestic maker of vinyl acetate produced only experimental lots, the bulk of our requirements being imported from Canada. In that year large units to manufacture vinyl acetate were built at Niagara Falls, N. Y., and at Belle, W. Va. The remarkable properties of safety glass made from vinyl resin sheets, together with several other new and important applications of these resins, indicatea demand for vinyl acetate sufficient to warrant these large manufacturing units. The United States patents covering the processes of manufacture of vinyl acetate are owned by the Canadian producer, who has licensed the domestic makers.
Domestic production of vinyl chloride has increased from experimental quantities in 1927 to large-scale commercial output, increasing substantially each year since 1933.
There has been no import of vinyl chloride. Imports of vinyl acetate (unpolymerized), entirely from Canada, are shown in table91.
Table 91.—Vinyl acetate, unpolymerized: United States imports for consumption, 1931-37
1Duty reduced from 30 percent ad valorem and 6 cents per pound to 15 percent ad valorem and 3 cents per pound under Canadian trade agreement, effective Jan. 1, 1936.2Preliminary.Source: Foreign Commerce and Navigation of the United States.
1Duty reduced from 30 percent ad valorem and 6 cents per pound to 15 percent ad valorem and 3 cents per pound under Canadian trade agreement, effective Jan. 1, 1936.
2Preliminary.
Source: Foreign Commerce and Navigation of the United States.
Domestic consumption of vinyl acetate and vinyl chloride has increased in recent years from experimental to commercial quantities. Many years of intensive research looking toward large outlets for the resins made from these compounds has apparently been successful. The largest single application indicated at this time is for safety glass sheets.
The large increase in domestic consumption expected in the immediate future will probably be supplied chiefly from expanding domestic production and imports from Canada will probably decline even under the reduced trade-agreement duty except to fill possible temporary shortages.