Heat stabilizers metallic soaps

Metallic soaps and salts of stearic acid and other organic acids are used both as lubricants and as auxiliary heat stabilizers. Metallic stearates are the most widely used lubricants. They are predominantly used in PVC, but also find use in polyolefins, ABS, polyesters, and phenolics. The primary disadvantage of metallic stearates is their lack of clarity. Calcium stearate, the most common metallic stearate, is primarily used as an internal lubricant, but in PVC applications it provides external lubrication and mold-release characteristics while also acting as a heat stabilizer. In addition to PVC, the calcium sterarates go into polypropylene, polystyrene, and ABS. Zinc stearates are used in crystal and impact polystyrene, ABS, and phenolics. 

Heat stabilizers protect polymers from the chemical degrading effects of heat or uv irradiation. These additives include a wide variety of chemical substances, ranging from purely organic chemicals to metallic soaps to complex organometaUic compounds. By far the most common polymer requiring the use of heat stabilizers is poly(vinyl chloride) (PVC). However, copolymers of PVC, chlorinated poly(vinyl chloride) (CPVC), poly(vinyhdene chloride) (PVDC), and chlorinated polyethylene (CPE), also benefit from this technology. Without the use of heat stabilizers, PVC could not be the widely used polymer that it is, with worldwide production of nearly 16 million metric tons in 1991 alone (see Vinyl polymers). 

Absorption of Hydrogen Chloride. Effective heat stabilizers have the abiHty to bind hydrogen chloride. Most stabilizer systems contain one or more metallic soaps or salts which readily undergo a simple acid—base reaction with the by-product hydrogen chloride as the PVC degrades ... 

The prints exhibit excellent application properties. They are, for instance, entirely fast to organic solvents, soap, alkali, and acids. They are also fast to sterilization. Metal deco prints demonstrate very good heat stability. The products withstand exposure to 200°C for 10 minutes or to 180°C for 30 minutes. Although not quite as fast to heat as halogenated types of Copper Phthalocyanine Green, P.B.15 3 is thus somewhat more heat stable than stabilized a-Copper Phthalocyanine Blue. 

The effects of release additives on bulk properties must also be carefully considered, particularly with integral additives to plastics. For example, partial solubility usually confers some plasticizing effect. This may improve impact strength but could reduce the heat distortion temperature. Some release additives such as metallic soaps have secondary antioxidant and heat-stabilizer benefits. Such effects are exploited in multipurpose formulations. 

Ethylhexanal, the reduced aldol condensation product of -butyraldehyde, is converted into 2-ethylhexanoic acid [149-57-5], which is converted primarily into salts or metal soaps. These are used as paint driers and heat stabilizers for poly (vinyl chloride). 

Commercial Stabilizers. There is a great variety of commercial formulations utilizing the mixture of the alkali and alkaline-earth metal salts and soaps. In many cases, products are custom formulated to meet the needs of a particular application or customer. The acidic ligands used in these products vary widely and have dramatic effects on the physical properties of the PVC formulations. The choice of ligands can affect the heat stability, rheology, lubricity, plate-out tendency, clarity, heat sealability, and electrical and mechanical properties of the final products. No single representative formulation can cover the variety of PVC applications where these stabilizers are used. 

Heat stabilizers - [HEAT STABILIZERS] (Vol 12) -m electric insulation [INSULATION, ELECTRIC] (Vol 14) -hydrazine derivatives as [HYDRAZINE AND ITS DERIVATIVES] (Vol 13) -lead compounds [LEAD COMPOUNDS - LEAD SALTS] (Vol 15) -metal soaps [DRIERS AND METALLIC SOAPS] (Vol 8) -for PVC foam [FOAMED PLASTICS] (Vol 11)... 

Typical lubricants are fatty alcohols C]2-C22, fatty acids C14-Ci8, their esters with fatty alcohols, glycerol or pentaerythritol, amides (2) or diamides (3) and metallic soaps (see Heat stabilizers ), acids C28-C31 from montan wax and their esters, diesters of phthalic acid (4b), paraffin wax C2o-C70, PE waxes Ci25-C70o or their oxidized (polar) grades containing hydroxyl and carbonyl groups. 

Lubricants are used in rigid PVC (PVC-U) in amounts 0.3-0.8% (metallic soaps acting primarily as heat stabilizers are used at levels up to 1.5 %). In polyolefins, calcium or zinc stearates used as antiacids provide the lubricating effect at 0.1 to 0.2%. Fluoropolymers are used specifically for L-LDPE. 

Concentration levels of heat stabilizers in various PVC products are in the range 1.5-3.0% for metal soaps and 0.3-2.5 % for organotin stabilizers (Pospfsil, 1990c). Aliphatic (22) or mixed aliphatic/aromatic phosphites (23, 24) are used together with polyols (e.g., pentaerythritol or sorbitol) and acid scavengers as co-stabilizers in PVC (Pospfsil, 1990c). 

Metal Soaps—Barium and cadmium stabilizers are less toxic than lead and have lower cost on the basis of use levels, better sulfide stain resistance, and good clarity. They are a major class of heat stabilizers. Calcium and zinc soaps are also included in this classification because of their similar performance. The soaps used are based on a wide variety of anions such as octoates (2-ethyIhexanoic acid derived), benzoates, laurates, stearates, and substituted phenolates. 

Reactivity toward HC1 has been used to rationalize the stabilization behavior of metal soaps and other metallic compounds (83), and the color-stabilizing properties of metal soaps in heated PVC have been shown to be influenced strongly by complementary color development (84,85,86). 

Owing to metal chlorides titration by the coulometric method, and carboxylic acid titration by the potentiometric method, it is possible to follow the metal soaps consumption during thermomechanical heat treatments. This new technique provides a better understanding of the stabilization mechanisms of PVC with the calciumr-zinc system, and offers a better explanation of synergistic effects between metal soaps and secondary stabilizers such as epoxidized soya-bean oil, a-phenylindole, and butanediol-p-aminocroto-nate. The influence of these last stabilizers on zinc chloride formation enables us to classify them into short- and longterm stabilizers. 

Knowing the quantity of metal chlorides and carboxylate acid liberated during thermomechanical heat treatments permits a better understanding of the stabilization mechanisms of metal soaps. This study confirms that the action time of stabilizer TA includes not only the primary... 

Stabilizers are almost invariably added to PVC to improve its heat and light stability. The species found effective in stabilizing PVC are those that are able to absorb or neutralize HCl, react with free radicals, react with double bonds, or neutralize other species that might accelerate degradation. Lead compounds, such as basic lead carbonate and tribasic lead sulfate, and metal soaps of barium, cadmium, lead, zinc, and calcium are used as stabilizers. Obviously, they can react with HCl. Epoxy plasticizers aid in stabilizing the resin. Another group of stabilizers are the organotin compounds, which find application because of their resistance to sulfur and because they can yield crystal-clear compounds. 

Flame retardants and heat stabilizers contain halogens, particularly bromine or phosphorus, or metal soaps such as stearates, pahnitates and octoates of... 

Properties Gardner 3 min. color high sol. in hydrocarbons and oils low sol. in water acid no. 220-310 3 max.% unsaponifiables MCRS Refined Naphthenic Acid [Merichem Chems. Refinery Services] Chem. Descrip. Naphthenic acid CAS 1338-24-5 EINECS/ELINCS 215-662-8 Uses Chem. and surfactant intermediate (derivs. used in paint and ink driers, lubricant/fuel additives, heat/UV stabilizers, cutting oils, and also wood preservatives, corrosion inhibitors, emulsifiers, defoamers, tire cord adhesives) prod, of metal soaps... 

Market Volume. The total market for PVC heat stabilizers may be about 100 million pounds in the United States and 1 biUion pounds worldwide, half for organotin and half for metal soap-epoxidized fatty ester-organic phosphite systems. 

Other stabilizers include special zincs for plasticized applications such as cable and organics added to calcium/zinc or used for pipe extrusion and co-stabilizers for metal soap and tin, improving long-term heat stability. Kickers (liquid barium/zinc and potassium/zinc) are PVC stabilizers that catalyse the decomposition of a blowing agent to be effective at lower temperatures, and can be used for sponge leather calendering. Epoxidized compounds are effective co-stabilizers in most systems chelators with metal soap improve heat stability. 

Fatty acid heat stabilizers are compounds consisting of fatty acids and metal ions and are also known as metal soap heat stabilizers. Their performances depend on the types of metal ions and acid radical groups. The general concentration is 0.1%-3.0%. 

Composite heat stabilizers are liquid or solid compounds based on salts or metal soaps and compounds based on organic tin. Metal salts include Ca-Mg-Zn, Ba-Ca-Zn, Ba-Zn, and Ba-Cd common organic acids include organic fatty acids, naphthenic acid, oleic acid, benzoic acid, and salicylic acid. 

Some additives used in plastics are surfactants but are not used primarily for their surface or interfacial activity. Rather they contain functional groups that, because of their chemical nature, are polar but they also contain non-polar groups, such as hydrocarbon chains, in order to provide compatibihty with the polymer. Good examples are the heat stabilizers used in plastics such as PVC to prevent thermal degradation. Typical additives used for this purpose are soaps (metal salts of alkyl carboxylates) or metal salts of other organic acids such as phenols. The metal cations used most commonly are tin, calcium, barium, zinc and cadmium. Lead salts are also used in electrical cables, pipes and window frames. Tin salts are especially useful for stabilizing clear, rigid PVC bottles. 

Metal soaps, which are external lubricants and are among the best mold-release agents. In some cases they improve heat and light stability of PVC. Examples Li, Sr, Ca, Al, Ba, Pb, etc., stearates. 

Heat stabilization by metallic soaps depends on their anions as weU as on their cations [37]. Affinity of anions to PVC plays an important role in their degree of dispersion in the polymer matrix [47]. 

Synergetic mixtures of metallic soaps (mainly Ba, Ca, Cd, and Zn) have found wide application as heat stabilizers [16,23,24,26,30,32,34-37,45,46, 48-53]. Synergism, in this case, is the action of two heat stabilizers achieving a higher stability than the best offered by only one of the two (see Section 10.2.6). 

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