Classification of tar-acid resins.
All the synthetic resins obtained by the condensation of a tar acid, or a mixture of tar acids, with an aldehyde are popularly called phenolic resins, regardless of whether they are made from phenol, the isomeric cresols, xylenols, other high boiling tar acids, or any mixture of these materials. A more accurate designation and that used in this survey is tar-acid resins, reserving the term phenolic resins for those made from pure phenol.
The tar-acid resins might be classified in a number of ways; for example, by composition, physical form, or general application. Each of these has its shortcomings. To classify them by composition, that is, by the kind of tar acid used, is not satisfactory because of the vast number of types made from mixed tar acids. For the purpose of this discussion it seems best to classify the tar-acid resins by their general application into six groups: for molding, for casting, for laminating, for surface coating (paints, varnishes, and lacquers), for adhesives, and for miscellaneous uses.
In 1937 approximately 66 percent of the United States production of tar-acid resins was made from phenol; 18 percent from phenol-cresol mixtures; 13 percent from cresol-cresylic acid mixtures; and 3 percent from cresol-xylenol mixtures. Table [2] shows for recent years production and sales of tar-acid resins by type of raw material. Pure phenol is used for cast resins. Molding resins are usually made from pure phenol or from tar-acid mixtures, chiefly phenol. Laminating and coating resins are usually made from mixtures containing substantial amounts of the cresols and xylenols (frequently spoken of by the trade as cresylic acid).
Table 2.—Tar-acid resins: United States production and sales, by type of raw material, 1933-37
| Year | Phenol | Tar-acid mixtures1 | ||||
|---|---|---|---|---|---|---|
| Production (net resin content) | Sales | Production (net resin content) | Sales | |||
| Quantity (net resin content) | Value | Quantity (net resin content) | Value | |||
| 1,000 pounds | 1,000 pounds | 1,000 dollars | 1,000 pounds | 1,000 pounds | 1,000 dollars | |
| 1933 | 25,163 | 21,851 | 5,383 | 6,535 | 6,152 | 1,182 |
| 1934 | 29,777 | 27,995 | 7,332 | 10,887 | 8,091 | 1,705 |
| 1935 | 36,323 | 34,597 | 6,568 | 16,654 | 12,371 | 2,200 |
| 1936 | 51,603 | 49,053 | 9,419 | 18,747 | 12,908 | 2,325 |
| 1937 | 52,472 | 50,209 | 8,616 | 27,373 | 23,337 | 4,685 |
| Phenol-cresol mixtures | Cresol-cresylic acid mixtures | Cresol-xylenol mixtures | ||||
| Production (net resin content) | Sales (net resin content) | Production (net resin content) | Sales (net resin content) | Production (net resin content) | Sales (net resin content) | |
| 1,000 pounds | 1,000 pounds | 1,000 pounds | 1,000 pounds | 1,000 pounds | 1,000 pounds | |
| 1937 | 14,046 | 13,238 | 10,702 | 8,467 | 2,625 | 1,632 |
1 Includes phenol-cresol mixtures, cresol-cresylic acid mixtures, and cresol-xylenol mixtures. For 1937, where it is possible, the totals of tar-acid mixtures are broken down into these three groups.
Source: Dyes and Other Synthetic Organic Chemicals in the United States, U. S. Tariff Commission.