Linoxin
As Linoxin (also Linoxyn , Linoxid or dried linseed oil ) refers to a mixture obtained by oxidative polymerization of linseed oil arises. When the linseed oil reacts with oxygen , the liquid oil changes over several intermediate stages into a solid, elastic, rubber-like film, whereby neither the exact course of the chemical reactions nor the structure of the linoxin are finally clarified.
Manufacturing, presumed structure and properties
The large-scale synthesis of linoxin as the main component of linoleum starts from linseed oil, which is first prepared by removing water and impurities. Oxygen in the air flows through the cleaned oil, mixed with drying agents, in oxidation drums at 80–120 ° C, whereby the linoxin is produced as a semi-solid, polymeric substance.
During the partial oxidation of linoleic acid , an unsaturated fatty acid bound as glyceride in linseed oil , polymeric, cross-linked structures are created via partly radical intermediate stages, which also contain unoxidized linseed oil in the form of an emulsion. In contrast to linseed oil, the oxidized linoxin dissolves in cold, weakly alkaline solutions with saponification , whereby glycerin and alkali salts of the fatty acids are formed. After further oxidation ( drying ), the proportion of linoleic acid contained continues to decrease, which could be followed very precisely by infrared spectroscopy , while the degree of crosslinking increases.
use
As a solid, linoxin is used as the main component of linoleum and linkrusta . For linoleum, it is mixed with cork flour and other materials and applied to a jute carrier fabric . Linkrusta consists of linoxin, rosin , copal resin , wood flour as well as dyes and fillers . The manufacture of both materials was patented in 1860 and 1877 by the British inventor Frederick Walton .
Particular importance has long been engaged in it Oil Painting : first indirectly, in that it just its properties both during the formation of the drying process are and the (far-reaching) after its completion, which linseed oil its position as one of the most important and common binder for pigments to Production of oil paints owes. On the other hand, in addition to linseed oil itself, it is also used directly as an additive in painting materials , mainly to thicken and accelerate drying.
Linoxin also plays a role in handicrafts as a binder for oil paints. Corresponding linseed oil colors are mixed with linseed oil varnish. The siccatives contained therein accelerate the oxidation of the linseed oil to linoxin. The oxidation dries the color, whereby the resulting linoxin binds or glues the colorants in its matrix.
Individual evidence
- ↑ Christian-Heinrich Wunderlich, Uwe Hilfrich: Linseed oil with drying process and sensitivities as well as complex varnishes. Restauro, 2003. ( [1] ).
- ↑ The Bauladen: Linoleum info: manufacturing .
- ↑ RJ Gettens, GL Stout: Painting Materials: A Short Encyclopedia , Courier Dover Publications, 1966, ISBN 9780486215976 .
- ^ Uwe Hilfrich: Bioinorganic chemistry in restoration: On the reactivity of metal complexing agents on historical painting surfaces. (PDF) Dissertation, 2004, Eberhard-Karls-Universität Tübingen .
- ↑ Pamela H. Simpson: Comfortable, Durable, and Decorative: Linoleum's Rise and Fall from Grace. APT Bulletin 30 (2/3), 1999; Pages 17-24.
- ↑ Wolfram Hiese (Ed.): Knowledge of building materials. Founded by Wilhelm Scholz. 13th edition, Werner Verlag, Düsseldorf 1995; Page 552.