Bad luck (fabric)

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Pech (from Middle High German bëch , pëch ; Latin pix ), also tar pitch , is a brown to black, tar-like or bituminous , viscous to solid, fusible residue that arises during the distillation of tars and organic substances after all light oils , intermediate fractions and heavy oils ( creosote , anthracene , etc.) are expelled. Pitch as a distillation residue should not be confused with bitumen , which is produced during the distillation of crude oil.

Definition of terms

In ancient times and in the Middle Ages , the terms “tar” and “pitch” were used synonymously. This often leads to confusion of terms. Pitch was often used in road surfaces where it was known as tar. Nowadays, DIN standards define what bad luck is (DIN 55946). Tars are created by the decomposing, thermal treatment ( pyrolysis ) of organic natural products (wood, coal, crude oil, etc.) and the resulting residues are called pitch.

History of meaning

The terms " Unlucky " and "bad luck" can be brought in connection with the use of pitch in the medieval defense of besieged fortresses. The second explanation for the expression "bad luck" goes back to medieval bird hunting . At that time, tree branches were coated with pitch so that the birds would stick to them and could be caught. Every bird that fell into the trap was “unlucky” and in that sense was a poor “unlucky one”.

The negative connotations of the word bad luck are numerous: "bad luck" in the fairy tale Frau Holle , " tarry and feather ", use for torture, the "pitch troughs" of hell and the like. a.

In the southern German and Austrian language area there is also the concept of tree pitch (Siedepech), often described as bad luck for the resin extraction fresh gained tree resin. The term Kaupech for gum-like tree resin species, which is also used as such, also falls into this language region . But these have nothing in common with the colloquial term pitch.

The term “ pitchblende” for uranium pecherz arose because it was thought to be a pitch-like variant of the zincblende , which later turned out to be an error. The brewer's pitch , which is usually a mixture of different additives, also falls into this category. There is also the term Saupech , Brühpech or brewing resin .

history

Pechofen in Hessenpark

The use of birch pitch can be proven archaeologically since the Paleolithic . The remnants of pitch from Königsaue are well- known and are at least 80,000 years old and are considered the oldest plastic in Europe. Birch pitch in particular seems to have been used here. Research from 2019 showed that usable amounts of birch pitch can be produced by simply burning birch bark near stone or bone surfaces. The birch pitch can be scraped off the surfaces after the burn. The use of bad luck is also described in three places in the Old Testament . Once during the construction of the ark , there pitch is used for sealing , after the birth of Moses for sealing the basket in which he was saved in the water of the Nile, and during the construction of the Tower of Babel , there pitch (bitumen) is mentioned as a binding agent for layers of clay bricks .

Of Theophrast (371-287 v. Chr.) And Pliny the Elder (23 / 24-79 n. Chr.) Originate early texts for pitch extraction. Pliny differentiates between the kiln- like smoldering process and the furnace production.

Originally the wood tar was extracted and boiled in coal piles or tar pit piles. The double pot method (allothermal) has also been archaeologically proven since the Middle Ages . A container with a perforated bottom, in which the reaction wood is located, sits on a collecting vessel . Both containers are surrounded with firewood and buried; smaller amounts of pitch could be obtained by burning the wood. After three hours of burning, the (tar) pitch yield was approx. 10% of the reaction wood used. The turpentine content was very high, so that the pitch was thin and only became more viscous with further boiling.

Large amounts of pitch (tar) were from the 17th century. In brick Pechöfen (tar, Schwelöfen single-chamber won) which raised about 8-10 m³ starting material and heated this up to seven days. Prerequisite were pine forests such as in the area. B. in the Dübener Heide in Saxony , also pitch (tar) was won on pitch oil stones .

In “Pechhütten”, Pechsieder processed tree resin (→ Pecherei ) by distilling the volatile components to “Siedepech”. - produced during boiling waste of resin residues, bark and dirt Access or greaves called - was in Grieb herds that as worked Kohlenmeiler, further processed.

Around 1850, commercial pitch-boiling was replaced by industrial production. In the late 19th century, pitch production reached its peak, as the sailing industry intensified. With the use of new plastics and the decline of sailing ships, pitch production finally became obsolete.

composition

  • Coal tar pitches are made up of high molecular weight cyclic and heterocyclic , mostly aromatic hydrocarbons , including PAHs , the molar masses vary between 2,000 and 30,000 u , as well as free carbon and soot-like components.

With regard to the physical structure, pitch, like tar, is to be regarded as a colloid system in which tar resins of various molar masses are distributed in an oily medium.

Manufacturing

  • Coal tar pitch: The majority of the distillation residues of peat, lignite, hard coal tar and slate tar results in pitch.
  • Wood tar pitch (wood pitch): The wood tar that arises during the extraction of charcoal is boiled or distilled, leaving the pitch as a residue.

In the past, when wood tar was boiled, the light fractions (“tar oils”) were lost, then finer (cobbler pitch) and coarser (normal) pitch and the residue the pitch cake .

Pitch is preferably made from resinous softwoods such as pine (for example Scots pine ) and spruce (for example Norway spruce ) or resinous deciduous trees such as birch and beech.

Bad luck with heavy contamination was created during autothermal pyrolysis - reaction wood and firewood are not separated - e.g. B. in the kiln in the tar pit , tar pit kiln, pitch furnace (single-chamber furnace) or in pit and slope piles . The quality of the pitch obtained is better with the allothermal pyrolysis ( double-pot method , retort , two-chamber furnace), since contamination through the separation of firewood and reaction wood is avoided.

  • Pitch can also be made from birch bark .
  • Resin pitch ( rosin pitch, formerly also Greek pitch ), tall oil pitch (sulfate pitch , tall pitch), sulfite pitch or cellulose pitch (cell pitch) from sulfite pulp production , wool fat pitch, stearin pitch (fat pitch), bone tar pitch, montan wax - Bad luck made. However, in terms of their composition and properties, these pitches cannot be compared with pitches made from coal and wood.

Pitch are divided according to their softening point , tough soft pitch (35 ° C to 50 ° C), the solid medium pitch or briquette pitch ( 60 ° C to 75 ° C) and the brittle, easily pulverizable hard pitch (75 ° C to 90 ° C) or higher. The softening point is the temperature at which the pitch changes into a soft, kneadable form. This is determined using the Kraemer-Sarnow method , DIN 52025.

By dissolving the pitch in heavy tar oils, the prepared tars are obtained, which are used as road, steel mill and roofing tar as well as pitch oil mixtures for the production of paints and insulating varnishes. Pitch coking results in a low-ash petroleum coke , which is mainly used to manufacture electrodes and nuclear reactor graphite . Electrode pitch and briquette pitch are also produced.

use

The pitch used to form the basis for road tar and building protection products . Similar to bitumen , they are high molecular weight resinous hydrocarbon compounds, the permanent or temporary plasticity of which is caused by low molecular weight oils.

Coal tar pitches were used because of their insensitivity to weather, industrial gases and aggressive water as well as their anti-bacterial and plant-hostile properties for coatings in building protection or as non-draining, high-quality corrosion coatings in industrial steel construction. Since ordinary tar pitches could only be used to a limited extent due to their low plasticity (about 30 K), so-called special pitches were developed by modifying the internal structure of these pitches (by enriching them with high-molecular tar resins). Sonderpeche are characterized by a particularly high plasticity (that is the range between the softening point and the breaking point ), which is made possible by the addition of fillers, e.g. B. Asbestos, up to 100 K could be increased.

(Wood tar) pitch was used for caulking in shipbuilding (as ship pitch or tar, Latin pix navalis ), lubricating, as well as fuel or glue and as a seal for wooden vessels (buckets, barrels) ( pichen ). Furthermore, pitch was used for pitch torches and in Greek fire .

As a shoemaker's bad luck: The soles of welted or doubled up shoes were previously sewn with a so-called pitch wire, which is made shortly before use from several linen threads that are rubbed with pitch, twisted together and provided at the ends with a pig or steel bristle. The pitch not only ensures that the thread is held together, but also that the seam is sealed. This method has been largely replaced in modern times by glued shoe bottoms or the use of plastic threads.

The remainder that was left over from the boiling of the pitch, the pitch cake , used to be burned together with highly smoking, resinous wood and processed into soot. In medieval warfare, for example, pitch was used to make incendiary arrows . When castles were besieged, buckets of hot pitch were poured onto the attackers by warriors (since the 19th century also known as “pitchfork”), however, rarely, if at all, as the production of large quantities of pitch was time-consuming and expensive.

How versatile pitch can be used nowadays is shown by z. B. the use as a polishing agent carrier for the production of large mirrors and the latest telescopes. A polishing agent suspended in water, for example cerium (IV) oxide , is rubbed over the surface to be polished with a thin layer of a mixture of two types of pitch (possibly mixed with beeswax).

Pitch of various origins is also used as an inexpensive raw material for the production of carbon fibers .

research

Demonstration of the high viscosity of pitch in the pitch drop experiment

To investigate the viscous material properties of pitch of the physicists began Thomas Parnell 1927, the so-called pitch drop experiment ( Pitch Drop Experiment ). The ninth drop fell in April 2014.

literature

  • Jürgen Falbe, Manfred Regitz: RÖMPP Lexicon Chemistry. Volume 4: M – Pk , 10th edition, Georg Thieme Verlag, 1998, ISBN 978-3-13-734910-5 , p. 3151.

Individual evidence

  1. ^ A b Kurt Arndt, J. Zellner: The artificial coals for electric ovens, electrolysis and electrical engineering. 2nd edition, Springer, 1932, ISBN 978-3-642-89488-6 , pp. 45-46.
  2. ↑ Judith M. Grünberg, Heribert Graetsch, Ursula Baumer, Johann Koller: Investigation of the Middle Paleolithic "resin remains" of Königsaue, district of Aschersleben-Staßfurt. In: Annual publication for Central German prehistory. 81, 1999, ISBN 978-3-910010-43-7 , pp. 7-38.
  3. ↑ Johann Koller, Ursula Baumer, Dietrich Mania: High-Tech in the Middle Palaeolithic: Neandertal-manufactured Pitch Identified. In: European Journal of Archeology . 4, 3, 2001, pp. 385-397, doi : 10.1177 / 146195710100400315 .
  4. ^ Judith M. Grünberg: Middle Palaeolithic birch-bark pitch. In: Antiquity. 76, 291, 2002, pp. 15-16, doi : 10.1017 / S0003598X00089638 .
  5. ↑ Neubacher, Breuer; State Office for Monument Preservation and Archeology Saxony-Anhalt: Bad luck for the hobby chemist
  6. ↑ Schmidt, P., Blessing, M., Rageot, M., Iovita, R., Pfleging, J., Nickel, KG; Righetti, L. & Tennie, C .: Birch tar extraction does not prove Neanderthal behavioral complexity . In: PNAS . August 19, 2019, doi : 10.1073 / pnas.1911137116 .
  7. ↑ Beda Venerabilis : In Genesim. P. 160 . ( limited preview in Google Book search).
  8. ↑ Teergrubenmeiler (PDF; 2.60 MB), on stadtentwicklung.berlin.de, accessed on February 6, 2017.
  9. ↑ Dieter Osteroth: Biomass: Return to the ecological balance. Springer, 1992, ISBN 978-3-642-77410-2 , p. 88.
  10. ↑ Herwig Hulpke, Herbert Koch Reinhard Nießner (ed.): RÖMPP Lexicon Environment. 2nd edition, Thieme Verlag, 2000, ISBN 3-13-736502-3 , p. 606.
  11. ^ A b Jürgen Falbe, Manfred Regitz: RÖMPP Lexikon Chemie. Volume 3: H – L , 10th edition, Georg Thieme Verlag, 1997, ISBN 978-3-13-734810-8 , p. 1787.
  12. ↑ L. Schmitz, J. Follmann: The liquid fuels: their extraction, properties and investigation. 3rd edition, Springer, 1923, ISBN 978-3-642-89309-4 , p. 114.
  13. ↑ Walter Fuchs, Fritz Glaser: On the question of the carbonization of hard coal and the possibilities of using the carbonization products. Springer, 1966, ISBN 978-3-663-06713-9 , p. 33.
  14. ^ Jean D'Ans , Ellen Lax : Pocket book for chemists and physicists . 2nd edition, Springer, 1943, ISBN 978-3-662-22464-9 , pp. 1732 ff.
  15. ↑ Federal Law Gazette . Part 2, No. 39, Bonn 1957, online ( memento of the original from October 1, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / www1.bgbl.de
  16. ↑ Bad luck on Spektrum.de, accessed on August 12, 2016.
  17. ↑ Dieter Osteroth: From coal to biomass. Springer, 1989, ISBN 978-3-540-50712-3 , p. 86.
  18. ^ Heinz-Gerhard Franck, Andre Knop: Coal Refinement: Chemistry and Technology. Springer, 1979, ISBN 978-3-540-09627-6 , pp. 119-120.
  19. ↑ Steward Observatory Mirror SOML Lab - LBT # 1 Polishing ( Memento of the original from January 9, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. at mirrorlab.as.arizona.edu, accessed August 12, 2016. @1@ 2Template: Webachiv / IABot / mirrorlab.as.arizona.edu
  20. ↑ Pitch drop touches down - oh so gently. The University of Queensland, April 17, 2014, accessed April 19, 2014 .

Web links

Wiktionary: Bad luck  - explanations of meanings, word origins, synonyms, translations
Commons : Bad luck  - collection of pictures, videos and audio files