Cadmium/zinc stabilizers

The system containing barium-cadmium-zinc stabilizer significantly outperformed the corresponding system based on tin mercaptide. The addition of the phosphite did not alter relative performance in Ba-Cd-Zn systems (Table VII). 

Ferro 1288. [Feno] Barium/cadmium/ zinc stabilizer heat stabilizer foi flexible vinyls. 

Typically, soHd stabilizers utilize natural saturated fatty acid ligands with chain lengths of Cg—C g. Ziac stearate [557-05-1/, ziac neodecanoate [27253-29-8] calcium stearate [1592-23-0] barium stearate [6865-35-6] and cadmium laurate [2605-44-9] are some examples. To complete the package, the soHd products also contain other soHd additives such as polyols, antioxidants, and lubricants. Liquid stabilizers can make use of metal soaps of oleic acid, tall oil acids, 2-ethyl-hexanoic acid, octylphenol, and nonylphenol. Barium bis(nonylphenate) [41157-58-8] ziac 2-ethyIhexanoate [136-53-8], cadmium 2-ethyIhexanoate [2420-98-6], and overbased barium tallate [68855-79-8] are normally used ia the Hquid formulations along with solubilizers such as plasticizers, phosphites, and/or epoxidized oils. The majority of the Hquid barium—cadmium formulations rely on barium nonylphenate as the source of that metal. There are even some mixed metal stabilizers suppHed as pastes. The U.S. FDA approved calcium—zinc stabilizers are good examples because they contain a mixture of calcium stearate and ziac stearate suspended ia epoxidized soya oil. Table 4 shows examples of typical mixed metal stabilizers. 

Organophosphoms compounds, primarily phosphonic acids, are used as sequestrants, scale inhibitors, deflocculants, or ion-control agents in oil wells, cooling-tower waters, and boiler-feed waters. Organophosphates are also used as plasticizers and flame retardants in plastics and elastomers, which accounted for 22% of PCl consumed. Phosphites, in conjunction with Hquid mixed metals, such as calcium—zinc and barium—cadmium heat stabilizers, function as antioxidants and stabilizer adjutants. In 1992, such phosphoms-based chemicals amounted to slightly more than 6% of all such plastic additives and represented 8500 t of phosphoms. Because PVC production is expected to increase, the use of phosphoms additive should increase 3% aimually through 1999. 

Antimony tris(isooctylthioglycolate) has found use in pipe formulations at low levels. Its disadvantage is that it cross-stains with sulfide-based tin stabilizers (122). Barium—zinc stabilizers have found use in plasticized compounds, replacing barium—cadmium stabilizers. These are used in mol dings, profiles, and wire coatings. Cadmium use has decreased because of environmental concerns surrounding certain heavy metals. 

The most commonly used stabilizers are barium, cadmium, zinc, calcium and cobalt salts of stearic acid phosphorous acid esters epoxy compounds and phenol derivatives. Using stabilizers can improve the heat and UV light resistance of the polymer blends, but these are only two aspects. The processing temperature, time, and the blending equipment also have effects on the stability of the products. The same raw materials and compositions with different blending methods resulted in products with different heat stabilities. Therefore, a thorough search for the optimal processing conditions must be done in conjunction with a search for the best composition to get the best results. 

Cathodic electrodeposition of microcrystalline cadmium-zinc selenide (Cdi i Zn i Se CZS) films has been reported from selenite and selenosulfate baths [125, 126]. When applied for CZS, the typical electrocrystallization process from acidic solutions involves the underpotential reduction of at least one of the metal ion species (the less noble zinc). However, the direct formation of the alloy in this manner is problematic, basically due to a large difference between the redox potentials of and Cd " couples [127]. In solutions containing both zinc and cadmium ions, Cd will deposit preferentially because of its more positive potential, thus leading to free CdSe phase. This is true even if the cations are complexed since the stability constants of cadmium and zinc with various complexants are similar. Notwithstanding, films electrodeposited from typical solutions have been used to study the molar fraction dependence of the CZS band gap energy in the light of photoelectrochemical measurements, along with considerations within the virtual crystal approximation [128]. 

Zinc, nickel, lead, and cadmium salts Ba-Cd-Zn stabilizers Organo-nickel complexes CdS, CdSe, lead stearate Cadmium laurate Stabilizers Pigments Lubricants... 

II elements invariably are not used singly, but in Subgroup A-B couples. Aside from lead compounds, the elements currently used in most applications are barium, cadmium, calcium, zinc, and tin—e.g., the calcium-zinc soap systems for nontoxic (food contact) applications, the general purpose barium-cadmium soap stabilizers, and the organotin stabilizers. The objective of this paper is to consider the rheological consequences of... 

Cadmium/zinc phosphite esters are also effective light stabilizers, as are WO3 and rare-earth-metal oxides. " Dibutyltin bis-isooctylthioglycolate is converted into the corresponding dibutylmonochlorotin ester and SnOCl2 during irradiation in PVC. ... 

The additives in PVC bottles for cooking oil and other food products must have FDA clearance. For flexible packaging materials, the most common stabilizers are mixed metals such as barium-zinc and calcium-zinc, which replaced the older cadmium-zinc formulations. For rigid blow molded containers and calendered sheets, or-... 

The most common mixed metal stabilizers are octoates, naphthenates and benzoates of barium and zinc metals which are liquids. Barium, cadmium and zinc stabilizers contain solid salts of fatty acids including stearates and laureates. Barium and cadmium provide the most effective thermal stability followed by barium and zinc and then calcium and zinc. However, cadmium is currently considered undesirable from environmental and health standpoints and is being replaced in heat stabilizers, particularly those for polymers used with food. 

The traditional stabilizer for hard PVC, harking back to the beginnings of PVC processing, is the cadmium-based stabilizer that was subsequently replaced by lead-based stabilizers for the most part in the 1980s. The demand for PVC formulae free of heavy metals has today led to an increasing use of calcium-zinc stabilizers free of heavy metals [23]. The many different demands made on modem PVC mixtures can hardly be met by one stabilizer alone, so that current practice frequently combined different stabilizer systems. Stabilizers are added to mixtures at ratios of around 14% by mass. 

Effective stabilizers against dehydrochlorination are inorganic and organic derivatives of lead as well as organic derivatives of barium, cadmium, zinc, and tin. The mode of action of these primary stabilizers has not been firmly established. With regard to the industrially important metal carbox-ylates, for example, zinc stearate, (CisH3iCOO)2Zn, a mechanism is discussed whereby the free acid and zinc chloride are first formed ... 

Mixed metal stabilizers. Mixed metal stabilizers are primarily used in flexible or semirigid PVC products. The most common are barium/zinc (Ba/Zn) metal salts. IVpical liquid barium, cadmium, and zinc stabilizer products consist of such salts as octoates, alkylphenolates, neo decanoates, naphthenates, and benzoates. Typical solid barium, cadmium, and zinc stabilizer products consist of the salts of such fatty acids as stearates or laurates. Generally, Ba/Cd products provide the best thermal stability, followed by Ba/Zn and finally Ca/Zn. However, Ba/Cd stabilizers have come under increased environmental and Occupational Safety and Health Administration (OSHA) pressure and are being replaced by cadmium-free products that are usually Ca/Zn and Ba/Zn. Several Ca/Zn stabilizers have been approved by the FDA for use in food-contact applications. 

Replacement of heavy metal formulations is influencing all development, and the introduction of cadmium/zinc systems in a more effective form is significant. Classically, stabilizers have used lead compounds and, on environmental grounds, manufacturers have volunteered to reduce levels to about 60% of today s usage by 2010. Calcium/zinc systems are now not included in the European Commission list of heavy-metal stabilizers, and these are seen as a key material for the future. 

Liquid stabilizers can be lubricating or non-lubricating and can contribute to colour and/or volatility, firstly throughout the process and subsequently in the finished product. They include barium/cadmium (zinc), barium/zinc. and calcium/zinc in technical and low-toxicity grades and stabilizer/activator combinations. Liquid barium/cadmium/zinc has been used for many years for the most demanding outdoor applications, such as coil coating. 

Environmental concern has promoted the development of systems to replace lead (especially from cables and cellular products). Cadmium-based stabilizers are also being phased out. To achieve the same effect, however, the replacements have to be complicated mixtures of salts. Organotin and calcium/zinc systems are favoured at present, but much will depend on the shape of any legislation in the future. In general, alternatives based on calcium and zinc are less effective, but are cheaper than those based on aluminium or magnesium. Water absorption can be a problem with systems not using heavy metals. 

In the IJS 2()0 million US market, the main heat stabilizers include lead compounds, organotin compounds, and mixed metal/salt blends based on chemicals such as barium, cadmium, and zinc, and significant changes are expected. Over US 75 million of the business is in lead- and cadmium-containing stabilizers, but these are under increasing scrutiny on health and safety grounds. 

The manifestation of synergic action among mixtures of substances belonging to different types of polyvinyl chloride stabilizers is mentioned not only in abundant patent literature, but also in many investigations. Data are cited on the high activity of mixtures of epoxy compounds with salts of cadmium, zinc, and organotin compounds [93-97]. 

In addition to modifying PVC with plasticizers, it is also necessary to incorporate heat heat stabilizers (qv) into the formulation in order to scavenge the HCl evolved at the processing temperatures, thereby reducing thermal degradation of the polymer. Typical heat stabilizers used for PVC are metallic compoimds of barium, cadmium, zinc, lead, and tin lead and zinc are the most common (257). 

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