Hydroxyethyl cellulose

from Wikipedia, the free encyclopedia
Cellulose and hydroxyethyl celluloses
( R = CH 2 CH 2 OH) with increasing molar degree of substitution from top to bottom
Hydroxyethyl cellulose, low degree of substitution
Hydroxyethyl cellulose, medium degree of substitution
Hydroxyethyl cellulose, high degree of substitution

Hydroxyethyl celluloses (HEC, also Hyetellose, Ethylose, Tylose H 300, UNII-8136Y38GY5) are cellulose ethers that are used as water-soluble, highly effective thickeners and binders. With small added amounts it results in a transparent, stable solution. HEC are water-soluble, yellowish-white, odorless and tasteless powders and are used in the construction sector (construction paints, for construction adhesives HEMC) and as a component of toothpaste.

Molecular formula

R = CH 2 CH 2 (OCH 2 CH 2 ) nOH,

Areas of application

Construction area

It can be used for water-soluble applications

  • Tinting paint
  • Exterior color
  • Solid color
  • Interior paint
  • Lime emulsion paint
  • Glue paint
  • Powder paint
  • Silicate paint
  • Silicone resin paint
  • Wall glaze
  • Cement paint
  • Dispersion tile adhesive (HEMC)
  • Dispersion joint filler (HEMC)
  • Dispersion adhesive (HEMC)
  • Synthetic resin plaster (HEMC)
  • Gloss filler (HEMC)

Pharma and Cosmetics

  • Component of toothpaste, e.g. B. Aminomed or Elmex jelly
  • Pharmaceutical excipient

Extraction and presentation

For the preparation of hydroxyethylcelluloses is alkali cellulose with ethylene oxide etherified . The OH group reacts preferentially on C-2 of the glucose units. Furthermore, ethylene oxide is also attached to hydroxyethyl groups that have already formed, so that polyglycol groups are formed. They are cheaper to make than methyl or hydroxypropyl cellulose. Manufacturers are Dow Chemical (formerly Union Carbide, "Cellosize"), Shin-Etsu ("Tylose H") and Ashland Inc. ("Natrosol HEC"), with production facilities in the USA and Brazil.

Hydroxyethyl cellulose V1.svg

Since not all hydroxyl groups react in this reaction, mixtures are formed with different degrees of substitution . The degree of substitution of the individual starch components within a polymer can also vary.

classification

Hydroxyethyl celluloses are characterized by their average degree of substitution (DS) and their molar degree of substitution (MS). Commercially available HEC have degrees of substitution of 0.85 to 1.35 (DS) or 1.5 to 3 (MS).

properties

  • Yellowish white powder or granules
  • Water-soluble from about 1 mol of ethylene oxide per mol of glucose, also soluble in some organic solvents if they contain water
  • Viscosity is not very sensitive to changes in the pH value and to electrolytes

Individual evidence

  1. a b c d e entry on hydroxyethyl celluloses. In: Römpp Online . Georg Thieme Verlag, accessed on February 25, 2015.
  2. ^ European Pharmacopoeia , Deutscher Apotheker Verlag Stuttgart, 6th edition, 2008, pp. 2806–2808, ISBN 978-3-7692-3962-1 .