Antioxidants other antioxidative stabilizers

Butylated Hydroxyanisole. 2- and 3-/ i -Butyl-4-methoxyphenol (butylated hydroxyanisole (BHA)) is prepared from 4-methoxyphenol and tert-huty alcohol over siUca or alumina at 150°C or from hydroquinone and tert-huty alcohol or isobutene, using an acid catalyst and then methylating. It is widely used in all types of foods such as butter, lard, and other fats, meats, cereals, baked goods, candies, and beer as an antioxidant (see Antioxidants Eood additives). Its antioxidant properties are not lost during cooking so that flour, fats, and other BHA-stabiLized ingredients may be used to produce stabilized products. 

Use Heat and light stabilizer for vinyl plastics and chlorinated paraffins. As an UV screening and antioxidizing stabilizer for vinyl and other chlorinated resins in paints and plastics. 

Of the compounding ingredients, fillers and plasticizers are more important in terms of quantities used. Other additives used in smaller quantities are antioxidants, stabilizers, colorants, flame retardants, etc. The ingredients used as antioxidants and light stabilizers, and their effect have been discussed previously. Fillers, plasticizers and flame retardants are described next. 

Antioxidants can be referred to as heat stabilizers and were previously discussed. Other heat stabilizers are metal complexes used in PVC and polyamide. The largest impact on colorability is with the metal complexes used to inerease the continuous use temperature rat-... 

Apart from colorant, other additives are also employed, such as antioxidants (stabilizers) or fillers. The latter reduce the article cost, because they are... 

Precaution Combustible Hazardous Decomp. Prods. Heated to decomp., emits acrid smoke and irritating vapors Uses Intermediate antioxidant, stabilizer for foods, oils, aviation and other gasoline, polyolefins... 

Synonyms Benzimidazolethiol zinc salt 2-Benzimidazolethiol, zinc salt 2H-Benzimidazole-2-thione, 1,3-dihydro-, zinc salt (2 1) Bis (mercaptobenzimidazolate) zinc Mercaptobenzimidazole zinc salt 2-Mercaptobenzimidazole zinc salt (2 1) Zinc benzimidazole-2-thiolate Zinc bis (1H-benzimidazole-2-thiolate) Zinc bis (1H-benzimidazole-2-thiolato)- Zinc mercaptobenzimidazolate Zinc mercaptobenzimidazole ZMB ZMBI Empirical Ci4HioN4S2Zn Properties M.w. 363.76 Toxicology LD50 (oral, rat) 540 mg/kg, (oral, mouse) 860 mg/kg TDLo (oral, rat, 30 days intermittent) 3240 mg/kg mod. toxic by ing. may cause liver effects, tumorigenic effects, other reproductive system tumors TSCA listed Hazardous Decomp. Prods. Heated to decomp., emits very toxic fumes of NOx, SOx, and ZnO Uses Antioxidant, stabilizer for rubbers Manuf./Distrib. ChemService http //WWW. chemservice. com... 

These stabilizers still have widespread use, but mainly in conjunction with other light stabilizers such as the hindered piperidines. Only in short-term applications do they tend to be used alone in conjimction, of course, with a hindered phenolic antioxidant and/or organic phosphite for process stability [1-3]. 

It can be used satisfactorily in combination with other stabilizers, for example other light stabilizers, phosphites, phenolic antioxidants, and their combinations. Its use in combination with a UV absorber such as 2(2 -hydroxy-3, 5 -di-/cr/-butylphenyl)-5-chloro-... 

Bicyclic phosphates have been used as flame retardants, antioxidants, stabilizers, and for spectroscopic studies. At present, however, they are being replaced by other compounds that are not so highly toxic. In a chemical structure (Figure 26.1), when R is substituted by isopropyl, the toxicity is very close to that of sarin (LD50 = 0.18mg/kg, i.m. in rats). Bicyclic phosphates act rapidly— within minutes following parenteral administration. Clinical S5unp-toms include behavioral perturbation, muscle weakness. 

There are many specialty plasticizers for polymers other than PVC of minor importance. Antioxidants/Stabilizers ... 

Both spandex fibers and mbber threads normally contain antioxidants and other stabilizers. 

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. 

Singk-Screw E.xtruders. These iacorporate iagredients such as antioxidants (qv), stabilizers, pigments, and other fillers iato plastics and elastomers (Fig. 

The chemical industry manufactures a large number of antioxidants (qv) as well as uv stabilizers and their mixtures with other additives used to facilitate resin processing. These companies include American Cyanamid, BASE, Ciba—Geigy, Eastman Chemical, Elf Atochem, Enichem, General Electric, Hoechst—Celanese, Sandoz, and Uniroyal, among others. The combined market for these products in the United States exceeded 900 million in 1994 and will reach 1 billion in the year 2000. 

A large number of hindered phenoHc antioxidants are based on the Michael addition of 2,6-di-/ f2 -butylphenol and methyl acrylate under basic catalysis to yield the hydrocinnamate which is a basic building block used in the production of octadecyl 3-(3,5-di-/ f2 butyl-4-hydroxyphenyl)propionate, [2082-79-3], tetrakis(methylene-3(3,5-di-/ f2 butyl-4-hydroxylphenyl)propionate)methane [6683-19-8], and many others (63,64). These hindered phenolic antioxidants are the most widely used primary stabilizers in the world and are used in polyolefins, synthetic and natural mbber, styrenics, vinyl polymers, and engineering resins. 2,6-Di-/ f2 -butylphenol is converted to a methylene isocyanate which is trimerized to a triazine derivative... 

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