Science: Greatest Waste

>U.S. synthetic rubber supplies may be stretched from two to five times by generous admixture of lignin, a gummy byproduct of the paper industry.

>U.S. plastics supplies can probably be doubled by addinglignin—and though plastics have been tiresomely fanfared as coming wartime substitutes for metals in civilian goods, engineers last week confessed that plastics are as scarce as metals, will go almost exclusively into armaments.

>In the last 30 days, use of lignin—itselfa plastic as well as a plastic “extender”—has increased fourfold in making airplane pattern plates.

This is the latest chapter in the utilization of lignin—the greatest industrial-waste on earth. In time, chemists believe, it will spawn as many useful derivatives as coal tar and become the basis of a great chemical industry. But so far, in spite of 40 years of head-scratching and an increasing number of derivatives, chemists have found uses for less than .05% of the 3,000,000 tons of lignin available each year in the U.S. and Canada. Yet lignin production goes merrily on, for it must be removed from wood pulp before the pulp is made into good sulfite papers.

Lignin is a dark, resinous substance lying like mortar among the cellulose-walled cells of all plants. It makes wood woody, constitutes about 25% (by weight) of the coniferous trees from which most paper is made. From the vats of U.S. mills every day are drained some 12,000,000 gallons of lignin waste. Papermen find it harder to get rid of than old razor blades. It is often poured into streams—a practice now forbidden in some States because the lignin absorbs free oxygen from the water, asphyxiates fish. Where stream pollution is forbidden, lignin wastes are now bothersomely and expensively dehydrated and burned—except at a few enterprising U.S. mills.

Marathon Strides. Highly enterprising is Marathon Paper Mills of Rothschild, Wis., makers of food containers and chemicals. In 1927 Marathon summoned Chemical Engineer Guy C. Howard, gave him a platoon of Ph.D.s and the job of finding more profitable channels for waste lignin than the Wisconsin River. Today, after 15 years of research costing some $2,000,000, Marathon adds lime to its waste liquors, precipitates out calcium lignin sulfonate, turns it into:

>Vanillin, the flavor constituent of vanilla. Last year one-half of U.S. vanillin was synthesized from U.S. lignin, consumed by General Foods, Hershey, National Biscuit, countless numbers of ice-cream makers, the Army & Navy.

>Tanning chemicals more efficient thantraditional tanbarks, which are increasingly scarce as U.S. imports are cut off and blighted U.S. chestnut trees (a major source) are becoming extinct.

>Agents which disperse cement more efficiently through sand, gravel, water.

>Water-softening agents, widely used in U.S. locomotives.

>Plastics in both common forms: 1) molding powders from which odd-shaped objects are pressed; 2) laminated sheets—i.e., layers of paper or cloth bound together and coated with lignin derivatives—which are used in such simple large-surface products as tabletops, refrigerator and airplane doors. Laminated lignin plastics are one-half the weight of aluminum, one-fifth the weight of steel. Pound for pound they are as strong as steel. The expanding U.S. output of lignin plastics can be used almost entirely for military purposes, e.g., parts for ships, tanks, planes, bomb fuses, cases for shipping shells, insulators.

Lignin plastics are the cheapest plastics yet devised; at 5¢ per lb. for the powder they cost only one-third to one-fourth the cost of most synthetic resins. But today they have a still greater advantage—they require as little as 2 or 3% phenol (carbolic acid), a chief component of the commonest plastics and now a badly needed, priorities-listed ingredient. Furthermore, lignin molding powders can be mixed to “extend” phenol plastics by 100%, synthetic rubber for many uses by 100 to 500%. This aspect of lignin was last week under intensive study by the U.S. Army & Navy.

As a road-binding material, lignin is widely used in New Jersey and Washington instead of tarry binders. This use was developed in the U.S. about 1905 by Jacob Robeson, pioneer industrial student of lignin. Robeson Process Co., unlike Marathon, removes lignin from pulp wastes by evaporation rather than by precipitation.

Theory Needed. All theseapplications still absorb only bucketfuls of the oceans of waste lignin pouring out of U.S. paper mills every day. Big reason for the slowness of lignin utilization is that, in spite of more than 60 years of research by scores of chemists, nobody has yet precisely determined its structure—what atoms in what pattern form its molecule. But when the theory is cleared up, useful applications will follow thick & fast. Reason: chemists will know what they are working with and can abandon the essentially trial-&-error methods now forced upon them. Chief center of molecular lignin research is the U.S. Forest Products Laboratory at Madison, Wis.