Synthetic resins and their raw materials / A survey of the types and uses of synthetic resins, the organization of the industry, and the trade in resins and raw materials, with particular references to factors essential to tariff consideration. Under the general provisions of section 332, title III, part II, Tariff act of 1930.

by United States Tariff Commission

THIOUREA

Thiourea (thiocarbamide) is a white crystalline solid, melting at 180° C. It is made commercially by treating a solution of calcium cyanamide with sulphur and ammonium sulphide or with hydrogen sulphide and ammonia. The principal uses of thiourea are in making intermediates and pharmaceuticals, as a photographic developer, as an insecticide, and in medicine. Because of the water resistance it imparts it was for some time widely used in urea resins. During the past few years, however, its use in resins has declined sharply owing to its deleterious action on ordinary molds and its slow rate of cure. In molding compounds, thiourea requires about 10 minutes curing time as compared with 3 minutes or less for urea resins and tar-acid resins. Since ways have been found to fabricate water-resistant urea resins without using thiourea, the consumption of thiourea in this use has declined.

There is no known commercial domestic production of thiourea.

Imports through the New York Customs District, according to invoice analyses made by the Tariff Commission, are shown in table [90]. Thiourea is dutiable at 25 percent under paragraph 5 of the act of 1930.

Table 90.—Thiourea: United States imports through the New York Customs District, 1931-37

Year	Quantity (pounds)	Value	Unit value	Source
1931	81,560	$24,254	$0.297	Germany and Switzerland.
1932	19,347	4,760	.246	Germany.
1933
1934	15,738	5,982	.380	Do.
1935	29,480	10,500	.356	Do.
1936	81,031	19,782	.244	Do.
1937	(1)

¹ Not available.

Source: Invoice analyses of paragraph 5, of Tariff Act of 1930. Compiled by U. S. Tariff Commission.