1941: Plastics

The use of plastics for defense purposes, which was considerable in 1940, took on a major crescendo in 1941. They were not only sold in increased amount in their normal markets, but due to the mandatory withdrawal of many metals from civilian uses, plastics were called upon to act as substitutes for such metals insofar as their properties would permit.

It has not been possible to obtain figures for the 1940 production in Germany or France, but it is believed that the 1941 world production of all plastics was upwards of 450,000,000 pounds, including plastic resins used in coatings.

Production.

The 1940 production in the United States can be given with reasonable accuracy. The total of all plastics, excluding alkyds used for coatings, is estimated to be approximately 180,000,000 pounds. The output of phenolic resins increased about 17 per cent to 33,000,000 pounds while urea resins increased 30 per cent to 22,000,000 pounds. Cellulose acetate molding powder increased 28 per cent, which more than offset the 11 per cent decrease in cellulose nitrate, keeping the cellulose group at about the same level, namely 35,000,000 pounds.

Obviously, information as to use of plastics in Germany, and other belligerent countries, is very slight, but study of captured German airplanes has indicated a large use of fabric impregnated phenol and urea formaldehyde; also methyl methacrylate, polystyrene, and vinylite.

German production of synthetic rubber required the production of large quantities of styrene, butadiene, and acrylonitrile, which are also intermediates in the production of plastics. The low cost secured by the large production induced a consequent increase in the amount of plastics made from these materials.

Scattered items of information from Germany indicate the use of cellulose triacetate for transmission belts, the use of polyvinyl chloride for wire insulation, for bristles, and for chemical tank lining. Other reputed applications were those of molded phenol formaldehyde for drive shafts and other parts of sewing machines. Due to its water-resistance, melamine formaldehyde was used for bathroom fixtures.

In Great Britain there was an enormous increase in the use of plastics for defense, although even here censorship has withheld vital information. Items that might be cited are melamine formaldehyde for plywood adhesives, development of many flexible substitutes for glass; urea formaldehyde for instrument scales, toilet flush bowl floats, and stuffing boxes; polyethylene for insulated cables, fabric re-enforced phenol formaldehyde for cams, screws, nuts, and fittings in railroad cars; and cellulose acetate for eye shields to protect against gas droplets. It was stated in a letter from London that large quantities of 'scratchproof unbreakable' polystyrene have been molded as opthalmic spectacle lenses for soldiers.

Plastics in Industry.

As in 1940, mechanical improvements in compression, as well as injection molding machines continued and in 600 plants there were 11,000 compression and 1,000 injection molding machines in use in 1941.

A new method of fabrication, namely extrusion molding, has furthered the use of cellulose acetate, cellulose acetate butyrate, methyl methacrylate and polystyrene. In this process molding powder is fed into a screw stuffer from which emerges a formed strip of any desired cross-section. These strips are used for wall moldings, shelf edgings, and other decorative trim, replacing aluminum and stainless steel.

The automotive industry continued to use quantities of cellulose acetate, cellulose acetate butyrate, methyl methacrylate, phenol formaldehyde and urea formaldehyde in interior fittings and outside decorations. There are some 110 plastic parts in the 1941 automobile, ranging from upholstery buttons to steering wheels, from accelerator pedal to laminated safety glass interlayer.

Another volume market was that of refrigerator parts. Certain refrigerators used 39 plastic parts. An insulating frame used in one make is said to be the largest piece ever injection molded.

Although not in commercial production, an automobile with a complete plastic body has been built, the material being phenol formaldehyde plus soybean filled with wood fiber pulp.

Phenol formaldehyde continues to be the largest volume item, especially in its laminated form and it has invaded new fields. In the airplane industry it found use as follows: pulleys, instrument boards and control tabs. In its laminated form it was used as a floor covering and in conjunction with soybeans for tractor seats. In its cast form it entered the toilet brush-back market in considerable quantity. Sulphonated, it was used in water-softening plants with a great degree of success. As a plywood adhesive it has been widely employed.

Urea formaldehyde increased its application in novel types of lighting fixtures and was used in larger quantity for articles such as bed lamps, door chimes, piano keys, and tissue dispensers. As an adhesive with casein it found wider use for plywood and as a generally useful cement. Plywood with urea-formaldehyde adhesive has been made into fabric covered panel boards as large as 8 by 20 feet.

Cellulose acetate and cellulose acetate butyrate molding powders increased their use in places too numerous to mention. Some of the newer articles are, fluorescent fish lures and electric switches; children's bassinettes, stage scenery, refrigerator parts, head protectors for baseball players, a wide variety of dress trimmings, beer cooling coils, children's toys, clothespins, Christmas tree ornaments, book bindings, arch supports, and oil dispenser cups. A compression-molded bus shade, 33' by 17' by 0.0195', made from cellulose acetate butyrate is one of the largest compression molded pieces yet made.

Cellulose nitrate, although still being substituted by cellulose acetate, continued to be made in large quantities.

Methyl methacrylate production continued its phenomenal increase and this beautiful plastic found many new uses. Its toughness, clarity, and light weight, has made it almost an essential material for cockpit and bomber enclosures in military airplanes. Other new uses were acid-resisting vegetable and fruit knives, brush backs, illuminated typewriter platens, all-plastic dentures, contact eye lenses, transparent silver chests, machine guards, beer dispenser boxes, machinery models, miniature furniture, house numerals, toothbrush handles, and juice extractor parts.

The polyvinyl resins, as a group, were widely used for defense, the vinyl chloride-vinyl acetate copolymer being used in large quantities for wire insulation. As rigid sheeting, the same copolymer has been used in shower curtains, airplane cockpits, in gas masks, sound records, storage battery separators, watch crystals, and dress trimmings. Its use was continued in flexible suspenders, belts, and wallets. As Vinyon it formed acid and alkali filter cloths.

Vinylidene chloride, a new plastic introduced in 1940, found added application as fish line leaders and water pipes.

Polyvinyl butyral is still considered the best plastic interlayer for automobile safety glass.

Nylon, the new synthetic monofilament, was more widely employed for bristles with added applications as tennis and badminton racket strings.

Polystyrene, because of its clarity and easy molding properties, enjoyed a greater market; among the articles made being salad sets, fluorescent light diffusers, hair curlers, toys and bathroom tiles.

And so plastics continue their onward march in the National Defense Program, and are finding new applications in civilian uses because of their inherent toughness, workability and beauty. See also CHEMISTRY.