Paraffinic oils oxidation stability

Almost all premium lubricants are so-called paraffinic oils composed primarily of both paraffinic and aUcycUc stmctures, with only a minor portion of aromatics. When stabilized with an oxidation inhibitor and fortified with other appropriate additives, these paraffinic—aUcycUc compositions provide nonsludging oils that are satisfactory for almost any type of service. 

Early refiners utilized simple batch distillation to prepare kerosenes and lubricating oils. As the demand for these materials expanded and new crude oils were found, certain desirable and undesirable characteristics became apparent. Crude oils were selected from which products possessing desirable characteristics could be distilled—for example, oxidation stability, low smoke tendency, low carbon-forming tendency, small viscosity change with change in temperature (high viscosity index), light color, and attractive appearance were more likely to be found in petroleum of the paraffinic or Pennsylvania type. 

Since paraffins have low volatility for their viscosity, high thermal and oxidative stability, and high VI, these new requirements could be met by using oils that are highly paraffinic. To meet mandated fuel economy and emissions standards plus customer demands will require large quantities of these advanced oils within the next few years. 

It was investigated that the viscosity index, pour point, oxidation stability, and other related properties of base oil depended on the composition and chemical nature of the aromatic, paraffinic, and naphthenic carbon contents (Yates et al., 1992). In this study, carbon types between KH150BS and filtrated oils were obtained using some base data of physical properties, and the method was similar to SH/T0729-2004. The results are shown in Table 5. 

The variety of substances used as additives in polymers is considerable. For example, the fillers may include china clay, various forms of calcium carbonate, talc, silicas (diatomaceous silica), silicates, carbon black, etc. The impact modifiers typically include other polymers. Plasticizers include certain polymers with low (oligomers), dialkyl phthalates, dialkyl sebacates, chlorinated paraffin waxes, liquid paraffinic fractions, oil extracts, etc. Heat stabilizers include heavy metals salts such as basic lead carbonate, basic lead sulfate, dibasic lead phosphite (also acting as a light stabilizer), dibasic lead phthalate, stearates, ricinoleates, palmitates and octanoates of cadmium and barium, epoxide resins and oils, amines, diphenylurea, 2-phenylindole, aminocrotonates. The antioxidants include tris-nonyl phenyl phosphite, 2,6-di-ferf-butyl-p-cresol (BHT), octadecyl-3,5-di-terf-butyl-4-hydroxyhydrocinnamate, etc. The UV stabilizers include modified benzophenones and benzotriazoles. Processing lubricants include calcium stearate, stearic acid, lead stearate, various wax derivatives, glyceryl esters and long-chain acids. Fire retardants include antimony oxide, some pyrophosphates, etc. 

Larger refineries with a wider product range can justify catalytic hydrogenation facilities. Olefins and aromatics are reduced to their saturated equivalents, paraffins and naphthenes. This method of decolorization decreases the number and extent of conjugated double bonded species and stabilizes the lubricating oil stocks toward oxidation. 

To lubricate high and ultra-high vacuum pumps special lubricants with low vapour pressures at the working temperature are used, produced from naphthenic or paraffinic mineral oils by molecular distillation with good oxidative and thermal stability. Synthetic esters are another group of lubricants for vacuum pumps, the most widely used are di-n-butyl and di-n-octyl phthalates. 

Chemical and physical stability also need to be considered. For example, Thoma and Holzmann (1998) showed that dithranol showed a distinct instability in the paraffin base due to light, but was stable when protected from light. In terms of kinetics, Kenley et al. (1987) found that the degradation in a topical cream and in ethanol-water solutions were very similar in the pH range 2-6. This suggested that the degradation of this compound occurred in an aqueous phase or compartment that was undisturbed by the oily cream excipients. If the compound decomposes due to oxidation, then an antioxidant may have to be incorporated. Table 6.8 lists the water soluble and oil soluble antioxidants that can be considered for incorporation into a topical formulation. 

Demulsifiers synthesized by polycondensation of an ethylene oxide-propylene oxide block copolymer, an oxalkylated fatty amine, and a dicarboxylic acid are known as polyester amines. These demulsifiers have the ability to adhere to natural substances that stabilize emulsions, such as organic materials formed by asphaltenes, oil resins, naphthenic acids, paraffins, and waxes they also adhere to inorganic particles formed by clays, carbonates, silica, and metallic salts. These properties increase the demulsification efficiency of the polyester amines [2, 5]. The availability of a variety of building blocks allows for the preparation of demulsifiers for specific applications. With this chemicd arsenal it is possible to tailor demulsifiers for nearly all problems posed by stable emulsions, including crude oil dehydration and desalting. 

Automatic transmission fluid (ATF) performs many functions including lubrication, power transfer, hydraulic control, and cooling [73], This fluid is extremely complex consisting of a base mineral oil (consisting of paraffinic, naphthenic, and aromatic hydrocarbons) and an additive package. Newer ATF compositions consist of synthetic base materials. The additives prevent fluid oxidation, corrosion, loss of lubricity, and foaming. Even though antioxidants, inhibitors, and stabilizers are added to the ATF, the base oil... 

Features Replaces or reduces chlorine or sulfur rec. where high temp, performance is required exc. thermal, oxidative, and hydrolytic stability biostable ashless contains no chlorine, sulfur, or phosphorous nonslaining Properties LI. amber sol. in all oils ind. paraffinic and naphthenic oils sp.gr. 0.99 (60 F) dens. 8.25 Ib/gal (60 F) vise. 40,000 SUS (100 F) vise, index 205 iodine no. 4 flash pi. > 400 F 8-12% free fatly acid (as oleic)... 

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