Bakelite


Bakelite, formally , is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. The first plastic made from synthetic components, it was developed by Belgian chemist Leo Baekeland in Yonkers, New York, in 1907, and patented on December 7, 1909.
Bakelite was one of the first plastic-like materials to be introduced into the modern world and was popular because it could be molded and then hardened into any shape.
Because of its electrical nonconductivity and heat-resistant properties, it became a great commercial success. It was used in electrical insulators, radio and telephone casings, and such diverse products as kitchenware, jewelry, pipe stems, children's toys, and firearms.
The retro appeal of old Bakelite products has made them collectible.
The creation of a synthetic plastic was revolutionary for the chemical industry, which at the time made most of its income from cloth dyes and explosives. Bakelite's commercial success inspired the industry to develop other synthetic plastics. As the world's first commercial synthetic plastic, Bakelite was named a National Historic Chemical Landmark by the American Chemical Society.

History

The reaction between phenol and aldehyde was first reported in 1872 by Adolf von Baeyer, though its use as a commercial product was not considered at the time.
Leo Baekeland was already wealthy due to his invention of Velox photographic paper when he began to investigate the reactions of phenol and formaldehyde in his home laboratory. Chemists had begun to recognize that many natural resins and fibers were polymers. Baekeland's initial intent was to find a replacement for shellac, a material in limited supply because it was made naturally from the secretion of lac insects. He produced a soluble phenol-formaldehyde shellac called Novolak, but it was not a market success, even though it is still used to this day.
He then began experimenting on strengthening wood by impregnating it with a synthetic resin rather than coating it. By controlling the pressure and temperature applied to phenol and formaldehyde, he produced a hard moldable material that he named Bakelite, after himself and the heat curing process it required. It was the first synthetic thermosetting plastic produced, and Baekeland speculated on "the thousand and one ... articles" it could be used to make. He considered the possibilities of using a wide variety of filling materials, including cotton, powdered bronze, and slate dust, but was most successful with wood and asbestos fibers, though asbestos was gradually abandoned by all manufacturers in the latter quarter of the 20th century due to stricter environmental laws.
Baekeland filed a substantial number of related patents. Bakelite, his "method of making insoluble products of phenol and formaldehyde", was filed on July 13, 1907, and granted on December 7, 1909. He also filed for patent protection in other countries, including Belgium, Canada, Denmark, Hungary, Japan, Mexico, Russia, and Spain. He announced his invention at a meeting of the American Chemical Society on February 5, 1909.
Baekeland started semi-commercial production of his new material in his home laboratory, marketing it as a material for electrical insulators. In the summer of 1909, he licensed the continental European rights to Rütger AG. The subsidiary formed at that time, Bakelite AG, was the first to produce Bakelite on an industrial scale.
By 1910, Baekeland was producing enough material in the US to justify expansion. He formed the General Bakelite Company of Perth Amboy, New Jersey, as a U.S. company to manufacture and market his new industrial material, and made overseas connections to produce it in other countries.
The Bakelite Company produced "transparent" cast resin for a small market during the 1910s and 1920s. Blocks or rods of cast resin, also known as "artificial amber", were machined and carved to create items such as pipe stems, cigarette holders, and jewelry. However, the demand for molded plastics led the company to concentrate on molding rather than cast solid resins.
The Bakelite Corporation was formed in 1922 after patent litigation favorable to Baekeland, from a merger of three companies: Baekeland's General Bakelite Company; the Condensite Company, founded by J. W. Aylesworth; and the Redmanol Chemical Products Company, founded by Lawrence V. Redman. Under director of advertising and public relations Allan Brown, who came to Bakelite from Condensite, Bakelite was aggressively marketed as "the material of a thousand uses". A filing for a trademark featuring the letter B above the infinity symbol was made August 25, 1925, and claimed the mark was in use as of December 1, 1924. A wide variety of uses were listed in their trademark applications.
The first issue of Plastics magazine, October 1925, featured Bakelite on its cover and included the article "Bakelite – What It Is" by Allan Brown. The range of colors that were available included "black, brown, red, yellow, green, gray, blue, and blends of two or more of these". The article emphasized that Bakelite came in various forms.
In a 1925 report, the United States Tariff Commission hailed the commercial manufacture of synthetic phenolic resin as "distinctly an American achievement", and noted that "the publication of figures, however, would be a virtual disclosure of the production of an individual company".
In the UK, Bakelite Limited, a merger of three British phenol formaldehyde resin suppliers, was formed in 1926. A new Bakelite factory opened in Tyseley, Birmingham, around 1928. It was the "heart of Bakelite production in the UK" until it closed in 1987.
A factory to produce phenolic resins and precursors opened in Bound Brook, New Jersey, in 1931.
In 1939, the companies were acquired by Union Carbide and Carbon Corporation.
In 2005, German Bakelite manufacturer Bakelite AG was acquired by Borden Chemical of Columbus, Ohio, now Hexion Inc.
In addition to the original Bakelite material, these companies eventually made a wide range of other products, many of which were marketed under the brand name "Bakelite plastics". These included other types of cast phenolic resins similar to Catalin, and urea-formaldehyde resins, which could be made in brighter colors than.
Once Baekeland's heat and pressure patents expired in 1927, Bakelite Corporation faced serious competition from other companies. Because molded Bakelite incorporated fillers to give it strength, it tended to be made in concealing dark colors. In 1927, beads, bangles, and earrings were produced by the Catalin company, through a different process which enabled them to introduce 15 new colors. Translucent jewelry, poker chips and other items made of phenolic resins were introduced in the 1930s or 1940s by the Catalin company under the Prystal name. The creation of marbled phenolic resins may also be attributable to the Catalin company.

Synthesis

Making Bakelite is a multi-stage process. It begins with the heating of phenol and formaldehyde in the presence of a catalyst such as hydrochloric acid, zinc chloride, or the base ammonia. This creates a liquid condensation product, referred to as Bakelite A, which is soluble in alcohol, acetone, or additional phenol. Heated further, the product becomes partially soluble and can still be softened by heat. Sustained heating results in an "insoluble hard gum". However, the high temperatures required to create this tend to cause violent foaming of the mixture when done at standard atmospheric pressure, which results in the cooled material being porous and breakable. Baekeland's innovative step was to put his "last condensation product" into an egg-shaped "Bakelizer". By heating it under pressure, at about, Baekeland was able to suppress the foaming that would otherwise occur. The resulting substance is extremely hard and both infusible and insoluble.

Compression molding

Molded Bakelite forms in a condensation reaction of phenol and formaldehyde, with wood flour or asbestos fiber as a filler, under high pressure and heat in a time frame of a few minutes of curing. The result is a hard plastic material. Asbestos was gradually abandoned as filler because many countries banned the production of asbestos.
Bakelite's molding process had a number of advantages. Bakelite resin could be provided either as powder or as preformed partially cured slugs, increasing the speed of the casting. Thermosetting resins such as Bakelite required heat and pressure during the molding cycle but could be removed from the molding process without being cooled, again making the molding process faster. Also, because of the smooth polished surface that resulted, Bakelite objects required less finishing. Millions of parts could be duplicated quickly and relatively cheaply.

Phenolic sheet

Another market for Bakelite resin was the creation of phenolic sheet materials. A phenolic sheet is a hard, dense material made by applying heat and pressure to layers of paper or glass cloth impregnated with synthetic resin. Paper, cotton fabrics, synthetic fabrics, glass fabrics, and unwoven fabrics are all possible materials used in lamination. When heat and pressure are applied, polymerization transforms the layers into thermosetting industrial laminated plastic.
Bakelite phenolic sheet is produced in many commercial grades and with various additives to meet diverse mechanical, electrical, and thermal requirements. Some common types include:
  • Paper reinforced NEMA XX per MIL-I-24768 PBG. Normal electrical applications, moderate mechanical strength, continuous operating temperature of.
  • Canvas-reinforced NEMA C per MIL-I-24768 TYPE FBM NEMA CE per MIL-I-24768 TYPE FBG. Good mechanical and impact strength with a continuous operating temperature of 250 °F.
  • Linen-reinforced NEMA L per MIL-I-24768 TYPE FBI NEMA LE per MIL-I-24768 TYPE FEI. Good mechanical and electrical strength. Recommended for intricate high-strength parts. Continuous operating temperature convert 250 °F.
  • Nylon reinforced NEMA N-1 per MIL-I-24768 TYPE NPG. Superior electrical properties under humid conditions, fungus resistant, continuous operating temperature of.