Synthetic rubber
As a synthetic rubber (indian. Cao 'tree' and ochu , Tear ') refers to elastic polymers from which rubber was prepared and based on petrochemical raw materials are prepared. The most important synthetic rubbers are styrene-butadiene rubber and EPDM .
In addition to synthetic rubber, there are types of natural rubber , mainly based on the milk juice (latex) of rubber tree ( Hevea brasiliensis ).
history
Around 1860 Charles Hanson Greville Williams was able to distill isoprene from natural rubber and determine the empirical formula C 5 H 8 . In 1879, he made it possible for Gustave Bouchardat to manufacture synthetic rubber for the first time in a process that lasted several months by heating isoprene made from rubber with hydrochloric acid and obtaining a rubber-like substance. Around 1900 Iwan Kondakow made the first fully synthetic rubber from 2,3-dimethylbutadiene . The first patent for the production of synthetic rubber was granted to Fritz Hofmann in 1909 . From 1915 to 1918, 2,500 tons of this synthetic rubber were produced at Bayer in Leverkusen.
During both world wars, Germany lost access to its rubber sources and the search for alternatives was encouraged. During the First World War Fritz Hofmann made so-called methyl rubber , a rubber substitute, from dimethyl butadiene . The first commercially usable synthetic rubber was styrene-butadiene rubber (SBR), an emulsion polymer of 1,3-butadiene and styrene developed by Walter Bock (with Eduard Tschunkur ) in 1929 . In 1930 Erich Konrad and Eduard Tschunkur developed butadiene-acrylonitrile rubber (NBR) and in the USA DuPont developed chloroprene rubber (CR), which is now sold as neoprene . In the USA, silicone rubber was created in 1942 and fluororubber in 1948 .
Rubber also became scarce during the Second World War, this time not only for the European Axis powers , but also for the Allies , since Japan had conquered the Asian plantations. In Germany, IG Farben began producing styrene-butadiene rubber in the Buna works under the name Buna from 1935 . Lignite was used as the raw material in Schkopau , for example, and the necessary hydrogen came from the neighboring Leunawerk .
From 1940 onwards, the state-owned US American Rubber Reserve Company was storing natural rubber because the USA feared a delivery stop in the event of an attack by Japan in Asia. When this happened, the USA began to build 15 state-funded factories for Buna rubber from 1941. The patents for styrene-butadiene rubber were held by Standard Oil of New Jersey , which, due to an agreement with IG Farben, refused to release the Buna patents for the American market, whereupon a commission of inquiry led the company to a "continued conspiracy in favor of Germany" accused and Harry S. Truman spoke at a press conference of "treason". The American Congress decided to release the Buna patents for America. In 1943, US production of 185,175 tons of "government rubber" exceeded German production of 110,569 tons for the first time and was increased to over 730,000 tons by the end of the war.
In the following years, more and more synthetic rubbers tailored to special needs were developed.
Manufacturing
Today rubber is mainly produced synthetically through polymerisation . It is usually made from styrene and 1,3-butadiene , other raw material bases are styrene acrylate , pure acrylate and vinyl acetate .
The polymer chains are usually made up of hydrocarbons . Chains based on silicone or other compounds are also possible.
Classification
Rubbers are divided into different groups according to the type of heteroatoms in the main chain.
| group | specification | Examples |
|---|---|---|
| R. | Double bond (s) in the main chain | Natural rubber , butadiene rubber |
| M. | saturated main chain | Ethylene propylene copolymer |
| N | Nitrogen in the main chain | Polyether amides |
| O | Oxygen in the main chain | Epoxy rubbers |
| U | Nitrogen and oxygen in the main chain | Urethane rubbers |
| Q | Siloxane groups in the main chain | Silicone rubbers |
| T | Sulfur in the main chain | Polysulphide rubbers ( thioplasts ) |
There are also various other modifications, which are also identified by letters.
| Type | modification |
|---|---|
| X | carboxylated rubbers |
| S. | Solution rubbers |
| EM | Emulsion rubbers |
| OE | oil-extended rubbers |
| B. | brominated rubbers |
| C. | chlorinated rubbers |
| Y | thermoplastic rubbers |
World production
Synthetic rubber currently accounts for around 60% of total rubber demand. In 1998, according to the International Institute for Synthetic Rubber Producers (IISRP), sales were 10.4 million tons, of which 70% went to the automotive industry. The top-selling synthetic grades are: styrene-butadiene rubber (SBR), polybutadiene rubber (BR), nitrile rubber (NBR), chloroprene rubber (CR) and ethylene-propylene-diene rubber (EPDM). Styrene-butadiene-latex (SBL) is important for the carpet industry and silicone rubber (SI) for applications at temperatures of up to 300 ° C.
use
Synthetic rubber can be used as a sole polymer or in blends with natural rubbers. Between 65% and 70% of all rubber goes into the production of car tires . Other main areas of application are binders for paper coating , carpet backing and dipped articles such as B. thin gloves.
In its foamed form, rubber is used for mattresses and sponges . It is also found in very thin films for condoms , gloves , or balloons and in thicker films for the production of casting molds , truck and passenger car tires , motor bearings , as well as various rubber / metal compounds. Neodymium- catalyzed polybutadiene rubber (Nd-PBR) is also found in high-performance tires .
Another important application is sealing profiles made of rubber. Due to the favorable weather properties, EPDM is mainly used for this. The sealing systems are produced by extrusion and often flocked , laminated and / or painted in a subsequent finishing process .
Rubber chemicals
Vulkacite or Vulkacit was introduced by IG Farben as a trade name for vulcanization accelerators . The successor company Lanxess still uses them today .
| Substance class | Chemical name | Trade name Lanxess | Trade name Chemtura | CAS number |
|---|---|---|---|---|
| Vulcanization accelerator | Zinc diethyldithiocarbamate | Vulkacite LDA | Ethazate | 14324-55-1 |
| Zinc dibutyl dithiocarbamate | Vulkacite LDB | Butacates | 136-23-2 | |
| Zinc dibenzyl dithiocarbamate | Vulkacite ZBEC | Arazate | 14726-36-4 | |
| N , N ′ -diphenylguanidine | Vulkacite D | 102-06-7 | ||
| N -cyclohexyl-2-benzothiazole sulfenamide | Vulkacite CZ | Delac S. | 95-33-0 | |
| N - tert -Butyl-2-benzothiazole-sulfenamide (TBBS) | Vulkacite NZ | Delac NS | 95-31-8 | |
| 2- (Morpholinthio) benzothiazole | Vulkacite MOZ | Delac MOR, NOBS SP | 102-77-2 | |
| 2-mercaptobenzothiazole | Vulkazit Merkapto / M | Naugex MBT | 149-30-4 | |
| Dibenzothiazyl disulfide | Vulkazit DM | Naugex MBTS | 120-78-5 | |
| Zinc-2-mercaptobenzothiazole | Vulkacite ZM | OXAF | 155-04-4 | |
| Thiuram (TMTD) | Vulkacite thiuram | Turex | 137-26-8 | |
| N , N ′ -di- o -tolylguanidine (DOTG) | 97-39-2 | |||
| Sulfur donors | Tetramethylthiuram tetrasulfide | Tetrons A | 97-91-6 |
swell
literature
- E. Konrad: About the development of synthetic rubber in Germany. In: Angewandte Chemie. 1950, 62, 21, pp. 491-496, doi: 10.1002 / anie.19500622102 .
- Heike Kloppenburg, Thomas Gross, Martin Mezger, Claus Wrana: The elastic century. Synthetic rubbers. In: Chemistry in Our Time. 2009, 43, 6, pp. 392-406, doi: 10.1002 / ciuz.200600515 .
Individual evidence
- ^ I. Franta: Elastomers and Rubber Compounding Materials . Elsevier, 2012, ISBN 978-0-444-60118-6 , pp. 65 ( limited preview in Google Book search).
- ↑ Jochen Streb: The development of the synthetic rubber industry in Germany and the USA before and during the Second World War ( Memento from January 10, 2012 in the Internet Archive ) (DOC file; 162 kB).
- ↑ Wolfgang Tietze: Handbuch Dichtungspraxis . Vulkan-Verlag GmbH, 2003, ISBN 3-8027-3301-0 , p. 15 . limited preview in Google Book search.
- ↑ Werner Baumann, Monika Ismeier: Rubber and rubber. Volume 1, Springer, 1998, ISBN 978-3-642-63788-9 , pp. 58-61. limited preview in Google Book search.
- ↑ Lanxess Vulkacit®: Products & Applications - Overview
- ↑ Accelerator DPTT ( Memento of the original of July 14, 2014 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ Rubber Chemicals Competitive Cross Reference
- ↑ Chemicals in rubber: 1.4.1 Crosslinking chemicals, accelerators
