Bakelite

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Bakelite
Structure of Bakelite
Identifiers
CAS number9003-35-4
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references
 
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Bakelite
Structure of Bakelite
Identifiers
CAS number9003-35-4
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Bakelite (/ˈbkəlt/ BAY-kə-lyt), or polyoxybenzylmethylenglycolanhydride, is an early plastic. It is a thermosetting phenol formaldehyde resin, formed from an elimination reaction of phenol with formaldehyde. It was developed by Belgian-born chemist Leo Baekeland in New York in 1907.

One of the first plastics made from synthetic components, Bakelite was used for its electrical nonconductivity and heat-resistant properties in electrical insulators, radio and telephone casings, and such diverse products as kitchenware, jewelry, pipe stems, firearms, and children's toys. Bakelite was designated a National Historic Chemical Landmark in 1993 by the American Chemical Society in recognition of its significance as the world's first synthetic plastic.[1] The "retro" appeal of old Bakelite products has made them collectible.

History[edit]

Dr. Baekeland had originally set out to find a replacement for shellac, made from the excretion of lac bugs. Chemists had begun to recognize that many natural resins and fibres were polymers, and Baekeland investigated the reactions of phenol and formaldehyde. He first produced a soluble phenol-formaldehyde shellac called "Novolak" that never became a market success, then turned to developing a binder for asbestos which, at that time, was molded with rubber. By controlling the pressure and temperature applied to phenol and formaldehyde, he produced a hard moldable material and patented in 1907 known as Bakelite.[2][3] It was the first synthetic thermosetting plastic ever made. It was often referred to as "the material of 1000 uses," a phrase originated by Baekeland himself.[4] He announced the invention at a meeting of the American Chemical Society on February 5, 1909.[5]

The Bakelite Corporation was formed in 1922 (after patent litigation favorable to Baekeland) from a merger of three companies: the General Bakelite Company, which Baekeland founded in 1910, the Condensite Company, founded by J.W. Aylesworth, and the Redmanol Chemical Products Company, founded by L.V. Redman.[6] A factory was built near Bound Brook, New Jersey, in 1929.[7]

Bakelite Limited, a merger of three British phenol formaldehyde resin suppliers (Damard Lacquer Company Limited of Birmingham, Mouldensite Limited of Darley Dale and Redmanol Chemical Products Company of London) was formed in 1926. A new factory opened in Tyseley, Birmingham, England around 1928. It was demolished in 1998.

In 1939 the companies were acquired by Union Carbide and Carbon Corporation. Union Carbide's phenolic resin business including the Bakelite and Bakelit registered trademarks are owned by Momentive Specialty Chemicals.

Properties[edit]

Phenolics are more rarely used in general consumer products today, due to the cost and complexity of production and their brittle nature. Nevertheless they are still used in some applications where their specific properties are required, such as small precision-shaped components, molded disc brake cylinders, saucepan handles, electrical plugs and switches and parts for electrical irons. Today, Bakelite is manufactured and produced in sheet, rod and tube form for hundreds of industrial applications in the electronics, power generation and aerospace industries, and under a variety of commercial brand names.

Bakelite distributor rotor
Bakelite letter opener circa 1920

Phenolic sheet is a hard, dense material made by applying heat and pressure to layers of paper or glass cloth impregnated with synthetic resin. These layers of laminations are usually of cellulose paper, cotton fabrics, synthetic yarn fabrics, glass fabrics or unwoven fabrics. When heat and pressure are applied to the layers, a chemical reaction (polymerization) transforms the layers into a high-pressure thermosetting industrial laminated plastic. When rubbed or burnt, Bakelite has a distinctive, acrid, sickly-sweet fishy odor.

Bakelite phenolic sheet is produced in dozens of commercial grades and with various additives to meet diverse mechanical, electrical and thermal requirements. Some common types include:

Note that phenolic resin products are apt to swell slightly if they are used in areas that are perpetually damp. Varnishing the product helps to prevent this.

Synthesis[edit]

Bakelite was a combination of phenol, formaldehyde, and wood flour. The mixture is put under pressure, and after curing, a hard plastic material forms.[8]

Applications and usage[edit]

Bakelite radio at Bakelite museum
Bakelite buttons, Chemical Heritage Foundation, Photograph by Gregory Tobias

In its industrial applications, Bakelite was particularly suitable for the emerging electrical and automobile industries because of its extraordinarily high resistance - not only to electricity, but to heat and chemical action. It was soon used for all nonconducting parts of radios and other electrical devices, such as bases and sockets for light bulbs and vacuum tubes, supports for electrical components, automobile distributor caps and other insulators.

Bakelite is used today for wire insulation, brake pads and related automotive components, and industrial electrical-related applications.

In the early 20th century, it was found in myriad applications including saxophone mouthpieces, whistles, cameras, solid-body electric guitars, telephone housings and handsets, early machine guns, pistol grips, and appliance casings. In the pure form it was made into such articles as pipe stems, buttons, etc.

The thermosetting phenolic resin was at one point considered for the manufacture of coins, due to a shortage of traditional material; in 1943, Bakelite and other non-metal materials were tested for usage for the one cent coin in the US before the Mint settled on zinc-coated steel.[9][10]

After the Second World War, factories were retrofitted to produce Bakelite using a more efficient extrusion process, which increased production and enabled the uses of Bakelite to extend into other genres: jewelry boxes, desk sets, clocks, radios, game pieces like chessmen, poker chips, billiard balls and Mah Jong sets. Kitchenware such as canisters and tableware were also made of Bakelite through the 1950s. Beads, bangles and earrings were produced by the Catalin Company, which introduced 15 new colors in 1927. The creation of marbled Bakelite was also attributed to the Catalin Company. Translucent Bakelite jewelry, poker chips and other gaming items such as chess sets were also introduced in the 1940s under the Prystal Corporation name; however, its basic chemical composition remained the same.

The primary commercial uses for Bakelite today remain in the area of inexpensive board and tabletop games produced in China, India and Hong Kong. Items such as billiard balls, dominoes and pieces for games like chess, checkers, and backgammon are constructed of Bakelite for its look, durability, fine polish, weight, and sound. Common dice are sometimes made of Bakelite for weight and sound, but the majority are made of a thermoplastic polymer such as acrylonitrile butadiene styrene (ABS).

Bakelite is used to make the presentation boxes of Breitling watches and sometimes as a substitute for metal firearm magazines. Bakelite is also used in the mounting of metal samples in metallography.[11]

Phenolic resins have been commonly used in ablative heat shields. Soviet heatshields for ICBM warheads and spacecraft reentry consisted of asbestos textolite, impregnated with Bakelite.[12]

US Patent 942699 for the bakelite product.

Patents[edit]

The United States Patent and Trademark Office granted Baekeland a patent for a "Method of making insoluble products of phenol and formaldehyde" on December 7, 1909.[13] Producing hard, compact, insoluble and infusable condensation products of phenols and formaldehyde marked the beginning of the modern plastics industry.[14]

Similar plastics[edit]

References[edit]

  1. ^ ACS National Historic Chemical Landmark, Bakelite: The World's First Synthetic Plastic (1993).
  2. ^ Amato, Ivan (29 March 1999). "Leo Baekeland". Time 100 (TIME). 
  3. ^ "Leo Baekeland". Plastics. 28 June 2000. 
  4. ^ Cook, Patrick (1993). Bakelite: An Illustrated Guide to Collectible Bakelite Objects. London: Apple. 
  5. ^ "New Chemical Substance" (PDF). The New York Times. February 6, 1909. 
  6. ^ American Institute of Chemical Engineers Staff (1977). Twenty-Five Years of Chemical Engineering Progress. Ayer Publishing. p. 216. ISBN 0-8369-0149-5. 
  7. ^ "Bound Brook". Dow.com. 2001-08-03. Retrieved 2014-05-07. 
  8. ^ Clegg, Brian. "Chemistry in its element - bakelite". Royal Society of Chemistry - RSC.org. Retrieved 4 May 2014. 
  9. ^ J2051/P2073 USPatterns.com. Accessed July 28, 2006
  10. ^ The New Yorker. Penny Dreadful. David Owen. March 31, 2008.
  11. ^ "''nasa.gov'', Metallographic Preparation Mounting". Grc.nasa.gov. 2008-05-13. Retrieved 2014-05-07. 
  12. ^ Roads to Space: an oral history of the Soviet space program
  13. ^ US patent 942699, Leo H. Baekeland, "Method of making insoluble products of phenol and formaldehyde", issued 1909-12-07 
  14. ^ "US Patent #942,699". Worldwide.espacenet.com. 1909-12-07. Retrieved 2014-05-07. 

External links[edit]