Schellack Chemische Eigenschaften,Einsatz,Produktion Methoden
Chemische Eigenschaften
Shellac is a natural resin that may be obtained in a variety of colors
ranging from light yellow to dark red in the form of hard, brittle
flakes with or without wax, depending on the refining process; see
Sections 4 and 13. The different types of shellac include bleached
shellac, bleached dewaxed shellac, dewaxed and decolorized
shellac, dewaxed flake shellac, dewaxed orange shellac, dewaxed
shellac, orange shellac, purified shellac, refined bleached shellac,
regular bleached shellac, regular waxy shellac, wax-containing
shellac, and white shellac. The flakes may be crushed or milled to a
coarse or fine powder. Bleached shellac is supplied as a coarse offwhite
powder.
Shellac is tasteless and may have a faint odor. The typical odor of
shellac is the result of a complex fragrance system.
Verwenden
Shellac is used in the preparation of cosmetic products such as mascara and acrylic nail products. It is also used in the formulation of aqueous-core capsules for riboflavin release.
Definition
shellac: A hard resin produced as asecretion by a plant parasite, thesouth-east Asian lac insect Laciferlacca. It is used in sealing wax, varnish(French polish), and electrical insulators.
Hazard
(Alcohol solution) Flammable, dangerous
fire risk.
Pharmazeutische Anwendungen
Shellac is widely used as a moisture barrier coating for tablets and
pellets due to its low water vapor and oxygen permeability. It has
usually been applied in the form of alcoholic or aqueous solutions
(pharmaceutical glazes). However, due to stability problems with
alcoholic shellac solutions, it has had limited use in the pharmaceutical
industry for modified-release or enteric coatings.
Shellac, particularly novel aqueous shellac solutions, is mainly
used in food products and nutritional supplements. Recent research
results indicate good application properties and chemical stability
of shellac films from aqueous shellac solutions. Aqueous
ammonium shellac solutions, based on dewaxed orange shellac,
do not show the problems exhibited by alcoholic shellac solutions
and are used as an enteric coating for pellets, tablets, soft and hard
gelatine capsules, primarily in nutritional supplements.
Shellac is a primary ingredient of pharmaceutical printing inks
for capsules and tablets, and can be applied as a 40% w/v alcoholic
solution. It has also been used to apply one or two sealing coats to
tablet cores to protect them from moisture before being film- or
sugar-coated.
Other applications of shellac are the coating or encapsulation of
powders or granules, e.g. in probiotics. Prior to the introduction of
film coating, a combination of shellac, cetostearyl alcohol and
stearic acid was used as an enteric coating. In cosmetics, shellac is
used in hairsprays, mascara and lipstick formulations. Aqueous
shellac solutions are also used for colonic drug delivery.
Sicherheit(Safety)
Shellac is used in oral pharmaceutical formulations, food products,
and cosmetics. It is generally regarded as an essentially nonirritant
and nontoxic material at the levels employed as an excipient.
Lager
After long periods of storage, shellac becomes less readily soluble in
alcohol, less fluid on heating, and darker in color.
Shellac should be stored in a well-closed container at temperatures
below 15°C. Wax-containing grades should be mixed before
use to ensure uniform distribution of the wax. Orange and dewaxed
orange shellac have a shelf-life of 1 to 2 years. The shelf-life of
bleached shellac is approximately 6 months.
Inkompatibilitäten
Shellac is chemically reactive with aqueous alkalis, organic bases,
alcohols, and agents that esterify carboxyl groups. Therefore,
shellac should be used with caution in the presence of such
compounds.
Regulatory Status
Accepted as a food additive in the USA, Europe, and Japan.
Included in the FDA Inactive Ingredients Database (oral capsules
and tablets). Included in nonparenteral medicines (oral tablets and
capsules, often in printing ink formulations) licensed in the UK.
Included in the Canadian List of Acceptable Non-medicinal
Ingredients.
Schellack Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
