Metallic stearate

Lubricants. Lubricants are used to improve the melt flow, screw feeding, and mold release of nylons. Long-chain acids, esters, and amides are used together with metal salts, eg, metal stearates. Improved melt flow is mainly a function of molecular weight reduction during mol ding. Mold release is improved by waxes of limited compatibiHty with nylon, which migrate to and lubricate the mold surface. 

More than half the metal stearates produced in the United States are appHed as lubricants and heat stabili2ers (qv) in plastics, particularly in the processing of poly(vinyl chloride) (PVC) resins. 

Stearate Product Specifications Tenneco Chemicals, Inc., Piscataway, N.J. Witco Metallic Stearates, bulletin 55-4K-5-63, Witco Chemical Corp., New York, May 1963. 

Butyl slurry at 25—35 wt % mbber continuously overflows from the reactor through a transferline to an agitated flash dmm operating at 140—160 kPa (1.4—1.6 atm) and 55—70°C. Steam and hot water are mixed with the slurry in a nozzle as it enters the dmm to vaporize methyl chloride and unreacted monomers that pass overhead to a recovery system. The vapor stream is compressed, dried over alumina, and fractionated to yield a recycle stream of methyl chloride and isobutylene. Pure methyl chloride is recovered for the coinitiator (AlCl ) preparation. In the flash dmm, the polymer agglomerates as a coarse cmmb in water. Metal stearate, eg, aluminum, calcium, or zinc stearate, is added to control the cmmb size. Other additives, such as antioxidants, can also be introduced at this point. The polymer cmmb at 8—12 wt % in water flows from the flash dmm to a stripping vessel operated under high vacuum to... 

Whilst lead compounds have been, and still are, the most important class of stabiliser for PVC the metallic soaps or salts have steadily increased in their importance and they are now widely used. At one time a wide range of metal stearates, ricinoleates, palmitates and octoates were offered as possible stabilisers and the efficiency of many of them has been examined. Today only the compounds of cadmium, barium, calcium and zinc are prominent as PVC stabilisers. 

Stearic acid and metal stearates such as calcium stearate are generally used as lubricants at a rate of about 1-3% on the total compound. Waxes such as camauba and ceresin or oils such as castor oil may also be used for this purpose. 

Metal stearates such as zinc, magnesium or aluminium stearates are commonly used as lubricants at about 1 % concentration. Other materials that have been used successfully include oxidised paraffin wax and sulphonated castor oil. 

Infrared measurement of additive concentrations is a more complex analysis than initially expected, as some additives may undergo a variety of chemical reactions during processing, as shown by Reeder et al. [128] for the FTIR analysis of phosphites in polyolefins. Some further examples of IR work refer to PVC/metal stearates [129], and PE/Santonox R [68,130]. Klingbeil [131] has examined the decomposition of various organic peroxyesters (TBPB, TBPP, TBPA and TBPO) and a peroxidicarbonate (BOPD) as a function of pressure, temperature and solvent by means of quantitative FTIR using an optical high p, T reaction cell. 

Crompton [21] has reviewed the use of electrochemical methods in the determination of phenolic and amine antioxidants, organic peroxides, organotin heat stabilisers, metallic stearates and some inorganic anions (such as bromide, iodide and thiocyanate) in the 1950s/1960s (Table 8.75). The electrochemical detector is generally operated in tandem with a universal, nonselective detector, so that a more general sample analysis can be obtained than is possible with the electrochemical detector alone. 

Neutralise acidity (e.g. deriving from acidic catalyst residues) effectively. Commonly salts of weak organic acids (metal stearates) or inorganic bases (hydrotalcite). Also called antiacids. 

Used to kill rest active catalyst residues, e.g. metal stearate and hydrotalcite. 

Thermal stabilisers for PVC are often heavy metal stearates (lead, barium), tin thiolates (R2Sn(SR2) = MZ2), and work by reacting the allylic... 

Newer polyacrylate rubbers can be cured with certain amines and are more responsive to a broad range of curative systems, e.g., alkali metal stearate/sulphur or sulphur donor, methyl zimate and ammonium adipate. 

Transition metal stearates have been shown not to have catalytic activity (206). The considerable literature on these systems, developed by Tulupov, has been reviewed, and the unique mechanism presented has been questioned (/, p. 384). 

Hoang, E.M., Liauw, C.M., AUen, N.S., Fontan, E., and Lafuente, P, Effect of Metal Stearate Antacid on the Melt StahiUzation Performance of Phenolic/Phosphite Antioxidants in Metallocene LLDPE. Part 1 Melt Processing Stahility /. Vinyl Addit. Technol., 10, 3, 137 (2004)... 

While discussing this subject, it is of interest to note that a recent advance in technique has been to obtain spectra when only one layer of material is adsorbed at a coverage of unity. Francis and Ellison (146) have obtained spectra of layers of metal stearates adsorbed on mirrors, and Pickering and Eckstrom (146a) have studied low molecular weight gases (such as H2 and CO) chemisorbed on metal mirrors. 

Because the forces of attraction prevail when molecules are brought into sufficiently dose proximity under normal conditions, release is best effected if both the strength of the interaction and the degree of contact are minimized. Aliphatic hydrocarbons and fluorocarbons achieve the former effect, finely divided solids the latter. Materials such as microcrystalline wax [64742 42-3] and hydrophobic silica [7631-86-9] combine both effects. Some authors refer to this combined effect as the ball bearing mechanism. A perfluoroalkylated fullerene nanosphere would perhaps be the ultimate example of this combined effect (17). These very general mechanistic remarks can be supplemented by publications on the mechanism of specific classes of release agents such as metallic stearates (18), fatty acids and fluorinated compounds (19), and silicone-coated rdease papers (20,21). The mechanism of release of certain problem adherents, eg, polyurethanes, has also been addressed (22,23). 

Exemplary water-repellent treatments for masonry surfaces include metal stearates, oils, waxes, acrylates (both polymers and monomers), silicones (solvent-based and emulsion), siliconates, silanes and, fluorochemicals. In contrast, to waterproofing coatings, water-repellent coatings, because they are permeable to water vapor, do not trap moisture and, therefore they can reduce spalling. In addition most water-repellent coatings do not alter the appearance of a porous masonry. 

Sears and Schulman (51) measured surface pressures and potentials vs. molecular area (20 to 110 sq. A. per molecule) for the alkali metal stearates over 0.5N solutions of LiOH, NaOH, and KOH. Like Adam and Miller, they detected a specific cation effect on the 7r-A and AV-A isotherms of the ionized monolayer at high pH the ir-A curves were expanded in the order of the crystalline sizes of the alkali metal cations K > Na > Li. The sequence is the reverse observed for the long-chain... 

Belt conveyor dryers yeast, charcoal briquettes, synthetic rubber, catalysts, soap, glue, silica gel, titanium dioxide, urea formaldehyde, clays, white lead, chrome yellow, and metallic stearates... 

Metallic Stearate Starch Adipic Acid Fiber Coal Filter Cake... 

Metal Stearates Spent 1 Grains Sewageb Sludge Starches Polystyrene Beads... 

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