wax
Wax ( Latin cera ) is an organic compound that melts at over 40 ° C and then forms a liquid of low viscosity . Waxes are almost insoluble in water , but soluble in organic, non-polar media . Waxes can be very different in their chemical composition and origin, which is why they are now defined by their mechanical-physical properties.
etymology
The term comes from Old High German : wahs (“beeswax, wax”) like “honeycomb” and “weave”, in Indo-European “ueg” ('weave', 'tissue').
definition
Due to the numerous groups of substances that show waxy behavior (which in practice also occur as mixtures of substances), an exact definition for waxes has not yet been found. The definition of the German Society for Fat Science is widespread : A substance is called wax if it is kneadable at 20 ° C, solid to brittle-hard, has a coarse to fine crystalline structure, is translucent to opaque in color , but not glass-like , melts above 40 ° C without decomposition, is slightly liquid above the melting point (not very viscous ), has a strongly temperature-dependent consistency and solubility and can be polished under slight pressure. If more than one of the properties listed above is not met, the substance is therefore not a wax.
Classification
Natural waxes
Natural waxes are divided into fossil and non-fossil (recent) waxes; they are lipids . The main components of these mixtures are esters of fatty acids (also called wax acids ) with long-chain, aliphatic , primary alcohols , the so-called fatty alcohols . These esters differ in their structure from the fats and fatty oils , which are triglycerides with fatty acids. These waxes also contain free, long-chain, aliphatic carboxylic acids , ketones , alcohols and hydrocarbons. The prototype of a wax acid is montanic acid (octacosanoic acid) C 28 H 56 O 2 . There is no precise distinction between wax acids and fatty acids, as typical fatty acids such as palmitic and stearic acid are also involved in the structure of some natural waxes . This structure results in a chemical definition of waxes in which the above-mentioned mechanical-physical properties are not necessarily met.
Natural waxes are usually obtained through extraction and subsequent cleaning and bleaching. Natural waxes are also refined or chemically modified for special applications.
Animal waxes
Animal waxes are, for example, wool wax , china wax , beeswax and rump gland fat , but also sebum and other insect waxes . Also spermaceti and shellac contain proportions of waxes.
Mycobacteria are the only known bacteria that form an outer shell made of special waxes, the phthiocerols .
Vegetable waxes
Wax layers on leaves and fruits have the task of protecting plants from water loss. Vegetable waxes include sugar cane wax , the carnauba wax of the carnauba wax palm, candelilla wax , which is obtained from various Euphorbiaceae , and, contrary to the name, Japan wax (berry wax) is a vegetable fat .
The jojoba oil is not composed of triglycerides and is therefore not a fixed oil , but chemically considered a liquid wax .
Other vegetable waxes are cork wax , Guarumawachs ( Calathea lutea ), ouricury ( Syagrus coronata ), Cuba palm wax ( Copernicia hospita ), esparto ( Lygeum spartum , Stipa tenacissima ), cotton wax , rice bran wax , flax wax , peat wax and Rose wax , jasmine wax or Peetha- Wax from wax gourd , as well as myrtle wax ( Myrica cerifera ) and wax fig wax ( Ficus variegata ).
Mineral / fossil waxes
Petroleum wax (mineral oil wax ), geological earth waxes ( ozokerite and the ceresin produced from it ), recent sediments of crude petroleum, the wax-rich (stuffed wax, vein wax) and low-wax (lepwax), the fossil plant waxes peat wax and montan wax (lignite derivative), they essentially consist from hydrocarbons . Petroleum distillate (petroleum derivative) that contains petroleum (slack wax) in addition to macrocrystalline, normal paraffins and microcrystalline wax. Tank bottom and tube wax can also be processed. These include soft, normal, hard paraffins (table paraffins ) (macrocrystalline), as well as microcrystalline wax (petroleum wax ), vaseline (petrolatum), the z. B. is used for candles and shoe polish .
Paraffins can also be obtained from shale oil (Messel paraffin ), brown coal smoldering (BK smoldering tar) or TTH paraffin (low-temperature hydrogenation paraffin from brown coal smoldering).
Semi-synthetic waxes
Semi-synthetic waxes are obtained from natural waxes; montan wax is often used as the basis, but other natural waxes are also used. Here the composition of the wax is influenced by physical or chemical changes; Oxidation (bleaching), hydrogenation , esterification , saponification , amidation .
Ester waxes are reaction products of long-chain wax acids with monohydric fatty or wax alcohols (partially saponified ester waxes, fully saponified ester waxes and emulsifier- containing ester waxes) (wax emulsifiers are mixtures of long-chain fatty alcohol ethoxylates ).
Amides of fatty and wax acids, wax alcohols of the esters replaced by aliphatic or aromatic amines. Natural (mono-, bis, poly) amide waxes (pseudoester waxes) based on fatty acids ( distearyl ethylenediamide (EBS) or (EDS) ethylenedistearmide); Stearic acid amide , behenic acid amide , erucic acid amide , oleic acid amide .
Others are carboxy , hydroxyl or carbonyl group- bearing waxes; One then speaks of acid waxes (high proportions of free carboxylic acids ), alcohol waxes (Lanette waxes) ( OH number- forming components predominate), ketone waxes ( carbonyl number- forming components predominate), ether waxes (predominantly compound containing ether groups ).
Acylated amides of fatty and wax acids (montanoyl aminocarboxylic acid). Alkylated imides of dicarboxylic acids , partially synthetic waxes from alkylated phthalimides (n-octa-decylphthalimide).
Others are phthalimide waxes, chlorinated hydrocarbon waxes, phenoxy derivatives, terphenyl waxes (non-substituted hydrocarbons; phenyl-substituted biphenyls ), waxy derivatives of succinic acid , waxy phenoxy derivatives; Alkyl phenoxy and diphenoxy compounds.
Also from different vegetable oils z. As soybean oil , rapeseed oil , castor oil can → by hydrogenation fat hardening soy wax , rapeseed wax , castor wax are produced.
Synthetic waxes
Synthetic waxes, hydrocarbon waxes (hydrocarbon waxes) are waxes obtained from synthetic products through processes such as (high, medium, low pressure) polymerization , condensation or addition ; they are mainly obtained from petroleum , but also from lignite .
( Polyethylene , copolymers ), polyolefin waxes: Polyethylene wax ( polar and non-polar), oxidized HD-PE waxes; polar PE waxes that are produced from HD-PE plastic by suspension oxidation . EVA waxes made from the plastic ethylene-vinyl acetate copolymer and polypropylene wax . Others are polyester waxes and polyethylene glycol waxes (PEG, Carbowax) and PTFE waxes and fluoro waxes → ski wax .
The Fischer-Tropsch waxes made from synthetic paraffins (FT paraffins) (hard wax, medium waxes) from natural gas , biomass and coal , they are used for a wide variety of applications.
Others are liquid waxes ; synthetic fatty acid esters , e.g. B. isopropyl myristate , isopropyl oleate , oleyl oleate and the like. a., reconstructed waxes , e.g. B. cetyl palmitate , lanette waxes , e.g. B. cetostearyl alcohol .
Micro waxes
Micronized waxes are a special form in which the particle size is greatly reduced up to an upper grain limit of around 30 μm. This can be done either by grinding ( jet mill , cold grinding ), with the melt dispersion process , by atomization ( spray cooling , PGSS process ) or by bead polymerization . In the atomization or melt-dispersion process, spherical, regular particles with a small surface are predominantly obtained, while in the grinding processes broken, irregular particles with a large surface are obtained. Pearl-shaped particles are obtained in bead polymerization. Micronized waxes are used instead of wax powders and wax dispersions in printing inks and coatings, e.g. B. to achieve abrasion resistance , scratch resistance, water-repellent effects, matting, sandability and to improve the sliding properties.
use
In addition to the uses already mentioned for candles , polishes and impregnations (e.g. wax paper for packaging ), waxes are used in foundries and because they are easy to mold for wax figures . In the fine arts, artists make models ( bozzetti ) for sculptures out of wax.
Jojoba oil and Japan wax are used in cosmetics . Special waxes are used for hair removal (see cold wax strips or warm wax ). They are also used in medical products such as dental wax preparations and as a raw material for soap production.
Waxes are used in construction to coat floors and wood. Polished waxes give surfaces a shiny appearance ( floor wax ), but also make them easier to slide ( ski wax ). Beeswax and some other natural waxes are approved as food additives (mostly as release agents ). For the historically correct restoration of furniture antiques (up to the Biedermeier period ; from then on, shellac was used), a special furniture wax, nowadays usually referred to as "antique wax", is used. It is rubbed into the wood and then polished off. As the name suggests, wax is an indispensable material for a wax museum ; These lifelike representations of the faces have not yet been achieved by any plastic .
Waxes are also used in the erotic area, see BDSM .
Historical
According to the legend, Daidalos , the father of Icarus , used wax to attach feathers to his and his son's arms and fly like a bird. Icarus got too close to the sun, which melted the wax; he fell and drowned in the sea.
Egyptian mummies are colored with wax paints; this technique is called encaustic . Nowadays, colored waxes are sold as crayons .
In the ancient and medieval medicine, the "pristine" light was virgin wax (of the non-incubated, not with honey or pollen coloring into contact coming in Honeycomb ) in the preparation of various drug use.
Sealing wax was until the 16th century to the sealing of documents used. It was then replaced by the sealing wax known as Spanish wax .
In Greece and Rome, wax tablets were used as a basis for writing notes, as what was written could be erased.
In the Middle Ages , the craftsman responsible was a highly respected profession: the gingerbread maker . He produced fine expensive candles ( Candlemas ), honey and gingerbread .
In the Renaissance , Baroque and Classicism periods , valuable furniture was rubbed with wax and polished.
Wax work , also known as monastery work , was made from wax, such as the well-known Fatschenkindel, especially at pilgrimage sites .
From the end of the 19th century until the 1920s, phonograph rollers first used wax as a sound carrier for a predecessor of the dictation machine and later as the source material for the original recording, which could then be reproduced in various processes after gilding . For the shellac records produced from 1895 to 1955, as well as for singles and LPs , a wax sheet was always used initially for the original recording, and after the Second World War it was still used to transfer the tape recording. After silvering , the wax plate was used as a die for making die copies with which the records could then be pressed en masse.
See also
- Wax-producing plants among useful plants , wax pullers , stearin
- Wax painting
literature
- Reinhard Büll: The big book of wax: history - culture - technology. 2 volumes, Munich 1977, ISBN 978-3-7667-0386-6 .
- NIIR Board of Consultants & Engineers: The Complete Technology Book on Wax and Polishes. Asia Pacific Business Press, 2011, ISBN 978-81-7833-012-9 (reprint).
- H. Bennett: Commercial Waxes. Second Edition, Chemical Publishing, 2011, ISBN 978-0-8206-0156-4 .
- Wilhelm Halden, Adolf Grün : Analysis of fats and waxes. 1st volume, Berlin 1925, ISBN 978-3-642-91637-3 .
- Wilhelm Halden, Adolf Grün: Analysis of fats and waxes. 2nd volume, Berlin 1929, ISBN 978-3-642-89318-6 .
- Emil Abderhalden (Ed.): Biochemisches Handlexikon. 3rd volume, Springer, Berlin 1911, ISBN 978-3-642-51194-3 .
- Carl Zerbe: Mineral oils and related products. 2nd edition, 2nd part, Springer, 1969, ISBN 978-3-642-87510-6 .
- F. Gieser: classification of waxes. In: fats, soaps, paints. 60, 1958, pp. 590-592, doi : 10.1002 / lipi.19580600716 .
Web links
- Plant waxes from materialarchiv.ch, accessed on March 9, 2017.
- Natural waxes; Key figures on chemie.varistor.ch, accessed on March 12, 2017.
Individual evidence
- ↑ a b Uwe Wolfmeier, Hans Schmidt, Franz-Leo Heinrichs, Georg Michalczyk, Wolfgang Payer, Wolfram Dietsche, Klaus Boehlke, Gerd Hohner, Josef Wildgruber: Waxes . In: Ullmann's Encyclopedia of Industrial Chemistry . June 15, 2000. doi : 10.1002 / 14356007.a28_103 .
- ↑ German standard methods for the investigation of fats, fat products, surfactants and related substances, MI 1 (75): German Society for Fat Science, Wiss.-Verl.-Ges.
- ^ Siegfried Hauptmann : Organic chemistry. 2nd edition, VEB Deutscher Verlag für Grundstoffindindustrie, Leipzig 1985, ISBN 3-342-00280-8 , p. 654.
- ↑ Otto-Albrecht Neumüller (Ed.): Römpps Chemie-Lexikon. Volume 6: T-Z. 8th revised and expanded edition. Franckh'sche Verlagshandlung, Stuttgart 1988, ISBN 3-440-04516-1 , pp. 4562-4563.
- ^ Brockhaus ABC chemistry. VEB FA Brockhaus Verlag, Leipzig 1965, pp. 1506–1507.
- ↑ Microwax on materialarchiv.ch, accessed on March 9, 2017.
- ↑ Fischer-Tropsch-Hartwachs on materialarchiv.ch, accessed on March 9, 2017.
- ^ Wilhelm Fresenius, Helmut Günzler, u. a .: Analyst paperback. Volume 4, Springer, 1984, ISBN 978-3-642-69343-4 , p. 389, limited preview in the Google book search.
- ↑ Ernst Steinegger, Rudolf Hansel: Pharmakognosie. 5th edition, Springer, 1992, ISBN 978-3-662-09268-2 , p. 63.
- ↑ Entry on micronized waxes. In: Römpp Online . Georg Thieme Verlag, accessed on March 30, 2017.
- ↑ Sebastian Pörschke: Production of powdered organic waxes and possible applications. Dissertation, Ruhr-Universität Bochum, 2014, urn : nbn: de: hbz: 294-40781 , (PDF; 4.82 MB), pp. 8-12.
- ^ Wolfgang Brückner : Cera - Cera Virgo - Cera Virginea. A contribution to "words and things" and to the theory of "substance holiness". In: Journal of Folklore. 59, 1963, pp. 233-253.
- ↑ Dieter Harmening: Keros parthenos - virgin wax. In: Journal of Folklore. 64, 1968, p. 30 f.
- ↑ Thomas Gleinser: Anna von Diesbach's Bernese 'Pharmacopoeia' in the Erlacher version of Daniel von Werdts (1658), Part II: Glossary. (Medical dissertation Würzburg), Königshausen & Neumann, Würzburg 1989 (= Würzburg medical historical research. Volume 46), p. 289 ( unused ).