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Calcium stearates, which are recognized as physiologically safe, have become increasingly important in the last few years. They are insoluble in most solvents. They dissolve only slightly when heated in aromatic compounds, chlorinated hydrocarbons or vegetable and mineral oils and waxes. Calcium stearates are mainly used as lubricants, mold release agents and acid scavengers by the plastics industry. The pharmaceutical and cosmetics industry uses calcium stearate as an anti-caking additive for powders and granules. The building industry uses it as hydrophobic agent for inhibiting moisture absorption and preservation of building materials and construction. |
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Zinc stearates are insoluble in polar solvents, but more soluble in aromatic compounds and chlorinated hydrocarbons when heated. Their main application areas are the plastics and rubber industries where they are used as release agents and lubricants which can be easily incorporated. The outstanding clarity and heat stability properties of our crystal clear zinc stearate grades make them particularly suitable for impact and crystal grade polystyrene and other clear polymers. Zinc stearate functions as an acid scavenger and processing aid in certain polyolefin applications.
The paint and coatings industry uses our zinc stearates for pigment suspension and to improve grindability and matting. The building industry uses powdered, precipitated zinc stearates as hydrophobic agents for plasters. |
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Like calcium stearates, magnesium stearates are almost insoluble in normal solvents. They are able to hold considerable quantities of water and take on a creamy consistency. Magnesium stearates are therefore used to improve the retention of creams and semi-rigid wax articles as well as to produce waxes.
Since they are recognized as physiologically safe, they are used by the cosmetics and pharmaceutical industry. Magnesium stearates improve the free-flowing properties and are added as anti-caking agents to powders.
One of the principle uses of magnesium stearate is as a tablet excipient in pharmaceutical dosage forms. Thermostable magnesium stearates are used as lubricants and release agents for the processing of thermoplastics and thermosets. |
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Aluminium stearates are produced by the precipitation process only. There are three possible combinations of aluminium with fatty acids:
The ratio of aluminium to fatty acid does not necessarily correspond to the stoichiometric values. Any ratio is possible between the extremes 1:1 and 1:3. Therefore there are many varieties of aluminium stearates, generically referred to as aluminium mono-, di- or tri-stearate, whose properties differ from one another in respect to physical properties such as melting point, free fatty acid and particularly the gelling properties. Oils with a low viscosity are best thickened by aluminium tri- and di-stearates, whilst very viscous oils form stiffer gel when combined with aluminium di- or mono-stearates.
The dropping point of aluminium greases usually range from 110 °C to 120 °C, but we are in a position to offer special stearates whose dropping point exceed 200 °C. All aluminium greases are highly hydrophobic and are characterized by outstanding transparency and good adhesion to metallic surfaces. Due to their excellent water repellency, aluminium stearates are used in coatings and building industry materials as water repellent ingredients. |
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Lithium stearates
Hydrophilic lithium stearates distinguish themselves by their excellent swelling properties. Different compositions of fatty acids are available in our product range. Depending on the product type properties like dropping point temperatures of greases containing lithium stearates are much higher than those of aluminium stearates.
Lithium stearates are widely used to thicken natural as well as synthetic oils and help to increase the melting point and flexibility of micro-crystalline waxes and paraffins. They are also used during the production of light weight metal moldings. The advantage of lithium stearates with long fatty acid chain lengths is the minimal residue after thermal treatment.
Sodium stearates and Sodium Oleates
Sodium stearates and oleates are produced by direct reaction according to a Baerlocher patented process. Possible applications of these products are e.g. swelling of alcohols, lubrication and nucleating during the processing of thermoplastics.
Sodium oleates are mainly used as hydrophobic agents for building plasters, where homogenous dispersion is easily obtained due to its solubility in water. The alkaline components of the plaster and the sodium stearate forms a calcium stearate which is also finely dispersed, thus imparting high water-repellency properties to the plaste. |
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