The alkyd resins are made chiefly from phthalic anhydride and glycerin. Phthalic anhydride in turn is made from naphthalene. Polybasic acids such as maleic, succinic, etc., may also be used with glycerin to form alkyd resins. Naphthalene, phthalic anhydride, maleic and other polybasic acids, and glycerin are discussed in the order named.

NAPHTHALENE

The discovery of naphthalene in coal tar was made simultaneously by Garden and Brande in 1819, and its composition was determined by Faraday in 1826 and later by Laurent in 1832. Naphthalene is almost invariably a constituent of the products obtained when organic matter is heated to comparatively high temperatures. For example, it is formed in small quantities when acetylene, alcohol, acetic acid, benzene, or toluene are heated to high temperatures. Together with certain aromatic hydrocarbons it is formed in the cracking of petroleum and in the hydrogenation of petroleum fractions. Naphthalene is a constituent of the principal varieties of tar produced from coal in the manufacture of gas and coke under ordinary conditions, but not of low-temperature tar. It is present in coal gas although its presence must be kept as low as possible to avoid blocking service pipes in cold weather. The proportion in gas tar varies with the kinds of coal used and is greater the higher the temperature used during carbonization; it usually amounts to 4 to 6 percent but is sometimes as much as 10 percent. In tars obtained from byproduct coke ovens the proportion of naphthalene and other aromatic hydrocarbons depends on the type of oven used. Byproduct coke-oven tar averages 10 to 11 percent naphthalene; blast-furnace tar contains only very small amounts.

Processes to synthesize naphthalene were described as early as 1873 by Aronheim, in 1876 by Wroden and Znatowicz, and in 1884 by Baeyer and Perkin. English Patent No. 26,061 of 1898 claims that it may be obtained by heating barium carbide with barium hydroxide to a high temperature. None of these processes has become of commercial importance.

Recovery of naphthalene.

Naphthalene is recovered in the distillation of coal tar, in the fraction boiling at 180° to 250° C., in the creosote oil fraction boiling at 240° to 270° C. and most abundantly in the carbolate or middle oil fraction boiling at 200° to 250° C. When these fractions are allowed to cool most of the naphthalene crystallizes out and is separated by draining and hot-pressing. This crude material is partially purified by washing with hot caustic soda solution to remove tar acids and then with mineral acid to remove basic substances. Refined naphthalene is obtained by subliming, or preferably by distilling the crude product.

Description and uses.

The Tariff Act of 1930 defines crude naphthalene as naphthalene solidifying under 79° C. after the removal of all water present; and refined naphthalene as that having a solidifying point at or above 79° C. after the removal of all water present.

Crude grades, melting between 70° and 78.5° C., are found in commerce as yellow, red, or brown crystalline solids. These grades are used in the manufacture of phthalic anhydride and other coal-tar intermediates; in the manufacture of lampblack; to enrich illuminating gas and sometimes motor fuel; in synthetic tanning materials; and in certain insecticides. Probably its most important outlets are as a raw material for phthalic anhydride (see p. 98) and refined naphthalene.

Refined grades, melting above 79° C., are marketed as white, crystalline lumps or flakes. Their principal uses are in the manufacture of intermediates, dyes, medicinals, solvents, and textile assistants; as moth repellants; as a lubricant when mixed with rapeseed oil; to remove the “bloom” from lubricating oils; as a preservative for rubber goods and animal skins; and in explosives (trinitro naphthalene). In 1936 more than 75 coal-tar intermediates made from naphthalene were commercially produced in the United States. Of the 75 million pounds of these intermediates produced in that year, 31 million pounds were phthalic anhydride, an important component of synthetic resins of the alkyd type.

United States production.

Crude naphthalene is produced in the United States by byproduct coke-oven operators, gas works that produce their own coal tar, and also by firms that purchase coal tar and distill it. Statistics of production by groups are shown in table 33.

Table 33.—Crude naphthalene: United States production, 1918-37

Refined naphthalene is obtained from domestic crude, imported crude, and recently from petroleum cracking and hydrogenation. Table 34 shows the annual production and sales of refined naphthalene since 1916. The difference between the figures for the quantity produced and that sold represents the amount used by refiners in the manufacture of other products.

Table 34.—Refined naphthalene: United States production and sales, 1917-37

Organization of the industry.—There are 10 domestic producers of crude naphthalene, operating 52 tar-distilling plants in the following States: Ohio (7), Pennsylvania (6), Illinois and New York (5 each), Alabama, Minnesota, and New Jersey (3 each), Missouri, Rhode Island, Wisconsin, Utah, West Virginia (2 each), and Michigan, Massachusetts, Maryland, Kentucky, Oregon, Connecticut, Tennessee, Indiana, Virginia, and Washington (1 each). Although these plants do not all recover naphthalene as such, they are equipped to recover a crude mixture of naphthalene and tar acids for shipment to a central extracting and refining plant. The principal producing plants are located in Pennsylvania (2), New Jersey (2), Illinois (1), Indiana (1), and West Virginia (1).

The purchasers of tar produced 77 percent of the total output of crude naphthalene in 1935 and 58 percent in 1936.

There are 8 producers of refined naphthalene located in the following States: New Jersey (3), Pennsylvania (2), California, Indiana, and Ohio (1 each).

Trend of production.—Although the United States is the largest producer of coal tar, the limited demand for the main products of tar distillation (creosote oil and pitch) has tended to restrict the amount distilled, thereby reducing the output of naphthalene and the tar acids to a point where the domestic output was not sufficient to meet our requirements. As a result, large quantities of these products have been imported. In 1936 we produced 560 million gallons of coal tar, containing from 400 million to 500 million pounds of naphthalene.[17] In the same year we distilled about 300 million gallons of tar, containing 230 million to 270 million pounds of naphthalene,[17] and our actual recovery of crude naphthalene was 89,536,000 pounds.

Early in 1935 the price of crude naphthalene was about 1.5 cents per pound or 15 cents per gallon, at which level there was little incentive to isolate it from the various fractions of tar distillation. Late in 1935 and in 1936 a serious shortage in naphthalene prevailed, largely because of increased demand by synthetic resin makers but also because of restrictions on exports from certain European countries. The price of the crude then advanced in domestic markets to from 2.5 to 3 cents per pound, with the demand greatly exceeding the supply. Between 1930 and 1936 the apparent consumption of crude naphthalene (production plus imports) increased from 59 million to 129 million pounds, or more than 100 percent. During the same period production increased from 31 million to 89 million pounds; and imports increased from 27 million pounds in 1930 to 48 million pounds in 1935 but declined to 40 million pounds in 1936.

Domestic producers of naphthalene are increasing their output, and they state that continued prices of 2.5 to 3 cents per pound for naphthalene solidifying at about 75° C. or slightly higher will stimulate production sufficiently to meet all present and near-future requirements. Estimates obtained in the summer of 1936 from the large tar distillers and a petroleum refiner indicate that production was appreciably greater in 1937 than in 1935. These estimates included the potential output of two new tar distillation plants under construction, the topping of large quantities of tar (hitherto used as fuel without removing any of the products), the recovery of appreciable quantities of naphthalene by several petroleum refiners, and increased output by other producers.

Imports of crude naphthalene in 1937 amounted to 52,664,277 pounds valued at $1,133,157, or 2.2 cents per pound.

World production.

The output of naphthalene in the principal producing countries, in 1933 and 1935, is shown in table 35. Most of these statistics were estimated from the output of tar or of other distillation products given in official reports of the countries or in consular reports.

The figures in table 35 indicate that the output in 1935 was an increase of about 100 million pounds over 1933 or 41 percent. Notwithstanding this sharp increase in world production, consumers had difficulty in obtaining their requirements. It is believed that the world output in 1937 substantially exceeded that in 1935.

Table 35.—Naphthalene (all grades): World production, by countries, 1933 and 1935

Germany.—Germany is the largest producer of naphthalene and the third largest producer of coal tar. With increased production of coal tar and intensive efforts to recover the maximum of naphthalene there has been a larger output of naphthalene in recent years, but increased consumption has created a scarcity in Germany as in all other important producing countries. As a result, greatly reduced quantities are available for export, a situation that is in marked contrast to earlier periods when superabundant production created a marketing problem. The manufacture of phthalic anhydride for alkyd resins is requiring increased quantities of naphthalene.

The demand for alkyd resins has been given a marked impetus by the development of a new standardized linseed oil varnish substitute known as El Varnish, the use of which is required by the Control Board for Industrial Fats in Germany for certain interior and exterior painting (see p. 77). Increased requirements for other important purposes such as intermediates, dyes, black pigments, and explosives have also contributed to the scarcity of naphthalene. In order to conserve domestic supplies, the Reich Government, from December 1935 until late in 1937 prohibited its export without special permit. The prospect of continued strong domestic demand apparently will curtail for an indefinite period the quantities available for export.

The international scarcity of naphthalene resulted in a sharp increase in its price in Germany as elsewhere. The export embargo augmented the domestic German supply, although a shortage still existed and large consumers found it difficult to secure adequate amounts. The shortage of foreign exchange greatly curtailed imports of naphthalene from nearby countries.

The German Government issued a decree requiring that beginning July 1, 1936, the entire national output of coal tar should be delivered to plants equipped for the recovery of tar products distilling up to 240° C. (naphthalene boils at 218° C.). This measure assured maximum recovery of benzol, toluol, xylol, solvent naphtha, phenol, cresol, xylenol, other tar acids, and naphthalene. The decree contemplated an official list of distillation units, and all tar producers were required to report to the official trade control board for mineral oil their monthly output, quantities distilled, and quantities delivered to other distillation plants.

German production, imports, exports, and apparent consumption of naphthalene are shown in table 36. Production increased from 108 million pounds in 1928 to 146 million pounds in 1935; imports decreased from 9 to 4 million pounds; exports decreased from 48 to 22 million pounds; and apparent consumption increased from 69 to 128 million pounds in the same years.

Table 36.—Naphthalene: German production, imports, exports, and apparent consumption, 1928-37

Sources: Consular reports (production); Der auswartige Handel (imports and exports).

Imports of naphthalene into Germany in past years have been supplied by nearby countries, notably the Saar (which became an integral part of Germany in February 1935), Belgium, Czechoslovakia, Poland, the Soviet Union, and others. The United States has been the most important foreign market for German naphthalene, taking from 50 to 75 percent of the total quantity exported. Other important buyers were Belgium, Italy, Japan, and France. Table 92 (see p. 144) shows the quantity and value of imports and exports by countries in recent years.

Great Britain.—The recovery and distillation of coal tar in Great Britain is highly developed. The annual output of tar, principally gas-works tar, is somewhat smaller than in the United States, although the quantities distilled for the recovery of separate components exceed the quantities distilled in the United States. In 1935 the tar distilled in England and Wales totaled 330 million gallons and in Scotland, 31 million gallons, or a combined total of 361 million gallons as compared with about 280 million distilled in this country.

Production of naphthalene in Great Britain is shown in table 37.

Table 37.—Naphthalene: Production in Great Britain, in specified years

Table 38 shows exports of naphthalene from Great Britain in recent years. The United States has been the best customer, in most recent years taking 50 percent or more of the total exported. Our imports from Great Britain have been entirely crude naphthalene, duty-free.

Imports of naphthalene into Great Britain are not shown separately in official statistics. It is known that the Netherlands exported small quantities to Great Britain in 1929 and 1933.

Table 38.—Naphthalene: Exports from the United Kingdom

Belgium.—The distillation of coal tar is one of the oldest and most important branches of the Belgian chemical industry. Approximately 90 batteries of byproduct-coke ovens, with a total of 3,000 ovens are in operation. Practically all of the coal tar produced in these operations is distilled for the recovery of the several products. The output of naphthalene is shown in table 39.

Table 39.—Naphthalene: Belgian production, 1928-35

Belgian imports and exports of naphthalene, by countries, are shown in tables 93 and 94 (see pp. 146, 147). Belgium is a net importer of crude naphthalene and a net exporter of refined naphthalene. In 1937, it imported 9 million pounds and exported 6.7 million of crude; it imported only 19 thousand pounds and exported 14 million pounds of refined.

Czechoslovakia.—The annual output of naphthalene in Czechoslovakia is shown in table 40.

Table 40.—Naphthalene: Czechoslovak production, in specified years, 1928-35

France.—Naphthalene is produced in France by a number of manufacturers, most of whom consume their production in their own factories. The French output is said to be insufficient to meet domestic requirements. Estimated production is given as approximately 30 million pounds annually. Appreciable quantities are imported from nearby countries. Imports from Belgium in recent years average between 1 million and 3 million pounds.

Poland.—Production of crude naphthalene in Poland is shown in table 41.

Table 41.—Crude naphthalene: Polish production, 1928-36

The Netherlands.—Statistics of production are not available. Exports in recent years, however, have averaged about 10 million pounds annually. It is believed that the production of crude naphthalene exceeds 15 million pounds a year.

Table 95 (see p. 148) shows Netherland imports and exports of naphthalene by countries in recent years. Imports in 1937 amounted to 2 million pounds and exports to 15 million pounds.

Canada.—Statistics of production are not available. The annual output of crude naphthalene is estimated at 2 to 3 million pounds.

Imports of refined naphthalene are usually about 1 million pounds (see table 96, p. 150). Exports are probably small, although in 1929 and 1934 those to the United States alone were over 1 million pounds.

The Soviet Union.—Statistics of production of naphthalene in the Soviet Union are not available. The annual output has been estimated at 10 million pounds in 1933 and 15 million pounds in 1935. Exports have increased substantially in recent years, those to the United States from 1 million pounds in 1934 to 6 million pounds in 1935. Exports to Germany were 361 thousand pounds in 1933; 1 million pounds in 1934; and 531 thousand pounds in 1935.

Japan.—Japanese production of naphthalene has been small compared with the output of other tar products. The output of crude naphthalene in 1934 was reported to have been 381 thousand pounds. Expansion of the byproduct coking industry in Japan and Manchuria has increased the production of coal tar, byproduct ammonia, and benzol. Japan has imported large quantities of naphthalene in recent years, principally from Germany and Belgium. The increased consumption in Europe may so reduce supplies from these sources as to cause Japan to increase the recovery at home.

Japanese imports of naphthalene from principal sources, are shown in table 97 (see p. 150). In 1936, 12.6 million pounds were imported.

United States imports.

Rates of duty.—Prior to September 8, 1916, all grades of naphthalene were imported free of duty. Since that time crude naphthalene has remained free but refined naphthalene has been subject to the tariff treatment shown in table 42.

Table 42.—Naphthalene: Rates of duty upon imports into the United States, 1916-38

Under the Tariff Act of 1930, crude naphthalene is on the free list[18] and refined naphthalene is dutiable at 7 cents per pound and 40 percent ad valorem on the basis of American selling price, since it is competitive with refined naphthalene produced in this country.[19] Under the trade agreement with Belgium, effective May 1, 1935, the duty on refined naphthalene was reduced to 20 percent[20] ad valorem and 3½ cents per pound on imports from that country. Under the Trade Agreements Act this reduction applies also to imports from all other countries which do not discriminate against commerce of the United States. In July 1938 Germany was the only one not receiving the reduced rate, exports from that country being subject to the rates specified under the Tariff Act of 1930.

Import statistics.—Table 43 shows imports of crude naphthalene (solidifying at less than 79° C.) and table 44 of refined naphthalene (solidifying at or above 79° C.) The unit invoice values of imports of refined naphthalene in 1924, 1926, 1927, 1928, and 1935 indicate that the imported product was probably not naphthalene as recorded but one of its derivatives provided for elsewhere in paragraph 27.

Table 43.—Crude naphthalene (solidifying at less than 79° C.): United States imports for consumption, in specified years, 1919-37

Table 44.—Refined naphthalene (solidifying at or above 79° C): United States imports for consumption, in specified years, 1919-37