PRODUCTS

ALUMINIUM STEARATE

Aluminum stearate is a white, wax-like powder (metallic soap) that dissolves in mineral spirits or hot oil.
A small amount (2% or less) added to oil paint imparts a short, buttery consistency.
Aluminum stearate eliminates the separation of pigment and oil, thickens varnishes considerably.
A concentrate of aluminum stearate and linseed oil can be prepared ahead of time and added to the paint whenever needed.

Aluminum stearate is made via the precipitation process using high quality stearic acid and exhibits the following properties: Good gelling and thickening action, excellent water repellency, transparency and a synergistic effect with zinc stearate or calcium stearate.

CAS: 637-12-7
European Community (EC) Number: 211-279-5

IUPAC Name: aluminum;octadecanoate

Molecular Weight: 877.4 g/mol
Molecular Formula: C54H105AlO6

Experimental Properties

Physical Description: Dry Powder; Pellets or Large Crystals

Color / Form: White powder

Melting Point: 118 °C

Solubility: Insoluble in water; soluble in ethanol, petroleum ether.

Density: 1.070

Stability / Shelf Life: Low melting solids or colorless, volatile liquids. /Alkylaluminum halides/

Decomposition: When heated to decomposition it emits acrid smoke and irritating vapors.

Other Experimental Properties: Forms gel with aliphatic and aromatic hydrocarbons.

Chemical Classes: Other Classes -> Stearates

Aluminium Stearate or is a white coloured powder, wax – like powder (metallic soap) that dissolves well in vegetable oils upon heating.
Aluminium stearate is soluble in glycol, alkali, BTX, chlorinated hydrocarbons.
If aluminium stearate is in high concentration, gelling can be seen upon cooling.
Aluminium stearate exhibits the following properties: good gelling and thickening action, excellent water repellence, transparency and a synergistic effect with zinc stearate or calcium stearate.
Aluminium stearate exhibits a relatively high solubility in hydrocarbon solvents (such as mineral spirits) when compared to other metallic stearates.
Aluminium stearate is insoluble in water, alcohol and ether; but when hot, it is readily soluble in benzene, acids and common solvents.

Aluminium distearate is the most commonly used grade of aluminum stearate.
Aluminium distearate is used as a thickener in paints, inks and greases; a water repellent for leather and rope; and a lubricant in plastics and rope.
Aluminium distearate is also used in cement production for waterproofing and air entrainment, and in hot-melt paper coating compounds.
Because of its unusually heavy bodying properties, aluminum monostearate is used in the manufacture of paints, inks, greases, and waxes.
In recent years, hydrophobic aluminum monostearate was tested as a low-solubility denitrification substrate for anaerobic bacteria and a source of aluminum for phosphate precipitation.
Aluminium stearate has potential for use in a flow-through container for denitrification of oxidized effluent from home sewage systems.
Aluminium stearate was also referred that the preheated mixture of metal soaps, along with the costabilizer, delayed the fast blackening of the polymer, but mainly showed a reduction.

Aluminium stearate is synthesised via the precipitation process using high quality stearic acid.
This is done by adding aluminium isopropoxide to stearic acid in anhydrous pyridine, inducing the precipitation of the pyridine complex.
Pyridine is then removed under vacuum to give the aluminium stearate.
Aluminium stearate is a fine, bulky, odourless and colourless powder forming a plastic mass when heated, having the properties both of organic and inorganic matter.
Aluminium stearate embraces most of the characteristics of other metallic stearates and is regarded as the most important of these.
Several studies of the material have already appeared in past years.

There are multiple types of aluminum stearates, generally classified as aluminum mono-, di-, and tri-stearate.
They vary in terms of physical properties such as melting point, free fatty acids, and particularly the gelling properties.
Oils with a low viscosity are best thickened by aluminum di- and tri-stearate, whilst very viscous oils from stiffer gel when combined with aluminum mono- or di-stearates.
All aluminium stearates are highly hydrophobic, and feature outstanding transparency and excellent adhesion to metal surfaces.
Due to their water repellency, aluminum di- and tri-stearate are used as hydrophobic agents in the building industry.

The earliest and simplest oil paints were mixtures of pigments and drying oils.
Eventually driers, resins, fillers, sometimes adulterants and suspension aids were also added.
Aluminium stearate was one of the components introduced in the 20th century.
The gelling of oil solutions by aluminum soaps was known since at least the late 19th century but the use of aluminum stearate to alter the properties of paint did not come into use until much later.

Aluminium stearate has been used to help suspend pigments in oil to prevent separation, to reduce the amount of oil needed to wet the pigment, and/or to increase the body of the paint by forming a gel with the oil thereby requiring less pigment.

Unlike calcium and zinc stearates that are available as 100% pure salts, the aluminum stearate as used in commerce is a non-stoichiometric compound.
The trivalent aluminum may be united with one or two stearate anions with the balance of the charge being neutralized by hydroxyl anions.
Aqueous systems for the preparation or use of disalts seems to lead to a range of products containing varying amounts of stearate, hydroxyl, and water units.
Anhydrous systems are needed to prepare stearates higher than the di-salt.
Commercial preparations of aluminum stearate may also contain anywhere from 2 to 7% by weight free stearic acid.
Analysis by weight of two commercial specimens by the author showed free stearic acid as 2 and 3% respectively.
Early preparations may also contain significant amounts of palmitate (from palmitic acid) since the commercial stearic acid used in the preparation of metal soaps was often only 90% pure.
Other fatty acids (palmitic, oleic, linoleic etc.) were also present as impurities.

Aluminum stearate dissolves in vegetable oils on heating and if a high enough concentration of the soap is used, gelling occurs on cooling.
In the usual practice of making paints, the aluminum stearate is ground with the pigment before the bulk of the oil is added.

In a series of experiments Gardner tested the effects of metal soaps on pigments.
Aluminum stearate was found to coat the surface of pigment particles and helped prevent settling as well as reducing the amount of oil needed to wet the pigment.
The amount of aluminum stearate needed to coat pigments varied on a weight basis, but a solution of 2% by weight (wt stearate/wt oil) aluminum stearate was more effective than 0.5% or 4% solutions in altering the surface.
The soaps coat the surface of the pigments and by steric effects or electrical charge mechanisms keep the particles from aggregating.
This keeps the pigments in suspension.

With increasing amounts of aluminum stearate the oil pigment mixture becomes viscous, and by using an appropriate amount of aluminum stearate the paint can gel at a lower pigment concentration.
This can be used to create a "cheaper" paint since a smaller amount of a costly pigment needs to be used.
A significant advantage of using stearates is that the oil and pigment do not separate greatly over long periods of time in the paint tube.

At present the manufacturers of artists' paints often use aluminum stearate in their formulations without listing it as a component.

Aluminium stearate is a fine, bulky, odourless and colourless powder forming a plastic mass when heated, having the properties both of organic and inorganic matter.
Aluminum stearate embraces most of the characteristics of other metallic stearates and is regarded as the most important of these.
Several studies of the material have already appeared in past years.

Aluminum stearate is used for waterproofing fabrics and for thickening lubricating oils.
Aluminum stearate is involved in the preparation of polyamides and thermosetting plastics.
Aluminum stearate is used as a waterproofing additive in cements and in light-sensitive photographic compositions.
Aluminum stearate acts as a gelling agent for alkyd paints, as a defoamer for oil drilling fluids and as a retarder for polysulfide dental impression materials.
Further, aluminum stearate is used in greases, lubricants, cutting compounds, cosmetics and pharmaceuticals.
Aluminum stearate serves as a flatting agent, as a defoaming agent in beet sugar and yeast processing.
In addition to this, aluminum stearate is used as a water-repellent soap for natural stone surfaces.

The effects of metal soaps on pigments have been extensively studied.
Aluminum stearate was found to coat the surface of pigment particles and helped prevent settling as well as reducing the amount of oil needed to wet the pigment.
The amount of aluminum stearate needed to coat pigments varied on a weight basis, but a solution of 2% by weight (weight of aluminum stearate/weight of oil) of aluminum stearate was more effective than 0.5% or 4% solutions in altering pigment surfaces.
The soaps coat the surface of the pigments and by steric effects keep the particles from aggregating, which helps to keep the particles in suspension.

Aluminium Stearate is one of numerous organo-metallic compounds for uses requiring non-aqueous solubility such as recent solar energy and water treatment applications.
Similar results can sometimes also be achieved with Nanoparticles and by thin film deposition.

Aluminium Stearate (C54H105AlO6) exists as white powder and is an aluminum salt of stearic acid.
In the pharmaceutical industry, aluminum stearate is used as an anticaking agent; colorant; emulsion stabilizer; and viscosity increasing agent.
According to the FDA, aluminum stearate is considered safe for general or specific, limited use in food.
Aluminium stearate is not classifiable as a human carcinogen (cancer-causing agent).

Solubility
Aluminium stearate exhibits relatively high solubility in hydrocarbon solvents (such as mineral spirits) when compared to other metallic stearates.
Aluminium stearate is insoluble in water, alcohol and ether; but is readily soluble in benzene, acids and common solvents when hot.

Storage
Aluminium stearate has long storage life if stored in cool and dry location.

How to Use
Aluminium stearate dissolves in vegetable oils on heating and if a high enough concentration of the soap is used, gelling occurs on cooling.
In the usual practice of making paints, the aluminum stearate is ground with the pigment before the bulk of the oil is added.
To prepare a concentrated solution (10% w/v), add 100 grams of aluminum stearate (nearly fills a half liter measuring cup without compacting) to one liter of linseed oil. Heat the oil to about 150° C.
and gradually slowly adding the white powder to the hot oil with stirring.
Add one part of this solution to four parts of oil by weight of oil before adding to pigments and grinding.

The Uses of Aluminium Stearate

Plastics Industry
Metallic stearates, which have been used primarily as acid scavengers, lubricants and release agents by the plastics industry, are becoming increasingly important in melt processing.
In addition to optimizing production, the use of metallic stearates allows the processor to produce finished articles with smoother surfaces and lower friction.
Metallic stearates are mainly produced from organic raw materials.
Therefore, they tend to degrade to some degree when exposed to excessively high temperatures, resulting in discoloration.
Fanchem has developed a range of thermostable metallic stearates, which are highly resistant to discoloration when used in transparent or brightly colored thermoplastics even at high processing temperatures

Cosmetics Industry
Aluminium stearate is used as an emulsifier in cosmetics.
They are used for their lubricating properties.
The stearate salts also increase the thickness of the oil portion of cosmetics and personal care products.
Hence, finished cosmetics products are typically not transparent.

Paint Industry
Aluminium stearate is used as a thickener in Varnishes/Lacquers, an anti-settling agent for pigmentation, as a pigment suspension, and an agent to improve water resistance and gloss.
Aluminium stearate is useful as a water repellent agent, a hydrophobic agent, and a waterproof agent in the paint industry.

SYNONYMS:

aluminum monostearate
aluminum tristearate
ammonium stearate
calcium stearate
magnesium stearate
octadecanoic acid
sodium stearate
stearic acid
zinc stearate
Aluminum stearate
Aluminium stearate
637-12-7
aluminium tristearate
Aluminum octadecanoate
ALUMINUM TRISTEARATE
Aluminum(III) stearate
Alugel 34TN
Metasap XX
Tribasic aluminum stearate
Octadecanoic acid, aluminum salt
Rofob 3
Monoaluminum stearate
Aluminum (III) stearate
Aluminum stearate (1:3)
Aluminum stearate, tribasic
Stearic acid, aluminum salt
HSDB 5733
EINECS 211-279-5
UNII-U6XF9NP8HM
U6XF9NP8HM
Aluminium tristearate, pure
SA 1500
Octadecanoic acid, aluminum salt (3:1)
Dihydroxy(octanoato-O)aluminum
AI3-01515
Aluminum, dihydroxy(octadecanoato-O)-
aluminum;octadecanoate
aluminum trioctadecanoate
Tristearic acid aluminum
aluminium trioctadecanoate
ALUMINUMTRISTEARATE
ALUGEL 30DF
ALUGEL 34TH
Stearic acid aluminum salt
Rashayan Aluminium Stearate
THOMPSON'S WATER SEAL
ALUMINUM STEARATE [II]
ALUMINUM STEARATE [MI]
DTXSID0027278
CHEBI:37867
ALUMINUM STEARATE [VANDF]
Octadecanoic acid, aluminium salt
CEGOLXSVJUTHNZ-UHFFFAOYSA-K
C18H36O2.1/3Al
ALUMINUM TRISTEARATE [HSDB]
ALUMINUM TRISTEARATE [INCI]
ALUMINIUM STEARATE [WHO-DD]
C18-H36-O2.1/3Al
AKOS015901563
DB11290
Octadecanoic acid aluminum salt (3:1)
ALUMINIUM STEARATE [EP MONOGRAPH]
LS-146665
FT-0622241
Q447821