Other Synthetic Base Stocks

Polyisobutylene (PIB) fluids are produced by the oligomerization of isobutylene in a mixed C4 stream over a BF3 or AICI3 catalyst. PIB are seldom used by themselves. They are typically used as blend stocks or as additives to increase lubricant viscosity. Table 10 summarizes the typical properties of selected PIB fluids . The VI and pour points of PIB are comparable to those of conventional mineral oil. PIB usually have a lower flash point and decompose easily into monomer at 200°C and higher. The advantages of PIB are their high compatibility with most synthetic or mineral base stocks and their relatively low cost compared to other synthetic base stocks. 

Alkylbenzenes and alkyinaphthalenes are produced by the alkylation of benzene or naphthalene with olefins using Friedel-Crafts alkylation catalysts. Their typical properties are summarized in Table 11. One unique feature of these alkylaromatic fluids is their very low pour points. Alkylbenzenes are often mentioned in the patent literature as components for CFC or HCFC lefiigeration compressor oil. Alkyinaphthalenes are used in synthetic automotive engine oil, rotary compressor oils, and other industrial oils. 

Commercial source V-9050 from Vista Chem. Co. Zero 150 from Chevron Synesstic 5 from ExxonMobil Chem. 

Phosphate esters are produced from phosphorus oxychloride with various alcohols or phenols, or combinations of these hydroxyl compounds. These fluids generally have good thermal and oxidative stabilities and fire-resistancy. However, because of their high polarity, poor Vl-pour point balance, facile hydrolysis and inferior elastomer and paint compatibility, their use in general lubrication is limited. The major use for phosphate esters is in fire-resistant hydraulic oils. 

S5mthetic lubricants have significantly raised the performance level of automotive and industrial lubricants with the help of high-quality PAO base stocks and tailored high-performance additive technologies. Equipment builders, industrial users and general consumers have taken advantages of the enhanced performance benefits afforded by synthetic lubricants - reduced 

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Hydrocarbons. Synthesized hydrocarbons are the most popular of the synthetic base stocks. These are pure hydrocarbons (qv) and are manufactured from raw materials derived from cmde oil. Three types are used olefin oligomers, alkylated aromatics, and polybutenes. Other types, such as cycloahphatics, are also used in small volumes in specialized apphcations. 

Other than the special supply circumstances of the Second World War, synthetic lubricants were not commercially significant until after the war. In general, the improved properties of lubricants achieved with early synthetic base stocks could be obtained more cost effectively by improved formulations based on mineral oils. But the requirement for lubricants to perform over increasing temperature ranges, led by military and aero-engine performance, stimulated continuing development of synthetic lubricant technology. Synthetic lubricants are now found in all areas of... 

Other properties, including friction coefficient, traction coefficient, biodegradability, resistance to radiation, etc. can be optimized for synthetic base stocks as required for their intended applications. 

As expected, the major producers of PAO, esters, PIB and alkylaromatics are integrated petroleum eompanies that supply conventional mineral oil base stocks and petrochemicals as well as various synthetic base stocks. PAG, phosphate esters and silicone fluids are manufactured by chemical companies that produce these fluids on a much larger scale mainly for other applications. Their use as lubricant base stocks is only a fraction of the total market. Table 1 summarizes the major synthetic base stock producers. 

Applications - Esters, both dibasic and polyol esters, are used as co-base stocks with PAO or other hydrocarbon base stocks in synthetic automotive engine lubricants and industrial lubricants. Polyol esters are used in aircraft tuibine oils due to their excellent thermal and oxidative stabilities, good lubricity, high VI and excellent low temperature properties (<-40°C). Esters are also used in synthetic compressor oils for ozone-ffiendly refngeration units. Because of their high biodegradability and low toxicity, esters are often the base oils of choice for many environmentally-aware... 

Although the viscosity index is useful for characterizing petroleum oils, other viscosity—temperature parameters are employed periodically. Viscosity temperature coefficients (VTCs) give the fractional drop in viscosity as temperature increases from 40 to 100°C and is useful in characterizing behavior of siHcones and some other synthetics. With petroleum base stocks, VTC tends to remain constant as increasing amounts of VI improvers are added. Constant B in equation 9, the slope of the line on the ASTM viscosity—temperature chart, also describes viscosity variation with temperature. 

As described in Chapter 1, mineral oil base stocks are derived from crude oil and are complex mixtures of naturally occurring hydrocarbons. Synthetic ester lubricants, on the other hand, are prepared from man-made base stocks having uniform molecular structures giving well-defined properties which can be tailored to specific applications. 

Group V base stocks include all other base stocks not included in the previous Groups I-IV, thus the polybutenes, synthetic esters, polyalkylene glycols and the phosphate esters are all included in this group. 

The subject of this book is the chemistry of petroleum base stocks and of their manufacturing processes from crude oil fractions. Petroleum base stocks are hydrocarbon-based liquids, which are the major component (80% to 98% by volume) of finished lubricants, the remaining 2% to 20% being additives to improve performance. Therefore this book does not deal with the manufacture of nonpetroleum base stocks such as synthetics (from olefins such as 1-decene), ester-based ones, and others. 

Esters, polyglycols, fluorocarbons and other fluid families with valuable tribological properties are not available in mineral oils. Functionalization of synthetic fluids expands the opportunities for performance enhancement and can bridge the gap between base stocks and additives. There is an equally wide variety of chemistry used in additive synthesis. 

Today, the most common types of synthetic dry strength additive are based on polyacrylamide although polyvinylamine strength additives are growing in popularity. This is because of the relatively low cost, and the ability to readily put an ionic charge onto these polymers. Other resins such as polyvinyl alcohol or lattices are used, but generally these are seen in surface applications to the paper, rather than as wet-end additives. Similarly styrene acrylic resins have shown superior performance when applied through surface application rather than as stock additives [8],... 

One of the directions of piperylene application is cationic oligomerization for production of liquid rubber - the base of synthetic drying oil of SKOP brand. Use of piperylene hydrocarbon fraction as feed stock for synthetic drying oil production allows solving the problem of isoprene production by-product utilization and reducing consumption of plant oils in paintwork and other industry branches [206,241, 242]. 

Natural rubber is also widely used in nontire applications which account for approximately 30% of the consumption of all rubber as an aggregate (including both natural and synthetic rubber). However, in the nontire sector, natural rubber was about 22% of total rubber consumption in 2012. Many times natural rubber is used as the sole base elastomer in compounds used in automotive bushings, motor mounts, vibration isolators, and dampers. On the other hand, NR is blended with SBR for compounds used in conveyor belts, welding hose covers, braided water hose, laboratory tubing, footwear knee boots, footwear microcellular compounds, footwear boot uppers, tank linings, and play balls. NR/BR blended compounds are used to make conveyor belt cover stocks, shoe soling, and so on. 

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