Lubricant Additives

Sulfur Carriers 275

Other applications for the combination of active sulfur and unsaturated ester are heavy-duty
gear oils in agricultural applications and environmentally-friendly chain saw and bar saw lubri-
cants (see Section 9.5.3.5).
If Cu corrosion presents a problem, the use of medium active sulfurized products in combination
with unsaturated esters is of advantage. Some of these sulfur carriers are active enough to create the
synergistic effects, but their Cu corrosion can be controlled with suitable yellow metal inhibitors.
Besides the improvement of EP and AW performance, inactive sulfur carriers can boost the AO
properties.
Saturated esters are used where good oxidation stability is required. The performance of sulfurized
products in saturated esters is comparable to the performance in mineral oil. Inactive sulfurized olefi ns
and sulfurized triglycerides, and mixtures thereof, are typically used as additives in lubricants based
on saturated esters.

9.5.5 COST-EFFECTIVENESS

Sulfurized products cover the whole range from relative cheap commodity to high-price specialty.
Depending on the type and treatment level, sulfurized products can be a major cost factor in lubricants.
However, the use of sulfur carriers enables us to run processes and to overcome lubrication problems
that cannot be solved in a cost-effi cient way with other additives. For example, it is possible to increase
machine speeds and thus productivity while using appropriate sulfur carriers instead of esters or
chlorinated paraffi ns. Depending on the type of sulfur carrier, other commonly used additives in a
formulation, for example, esters or yellow metal deactivators, can be saved. In comparison with heavy-
metal- or chlorine-containing lubricants, the disposal costs for the used lubricant can be much lower.
Besides direct cost savings, respectively, cost effi ciency due to higher productivity and lower
disposal costs, there are secondary cost factors. In comparison with some traditionally used EP
additives such as chlorinated paraffi ns (HCl-formation > rust), overbased sulfonates (diffi cult
degreasability, incompatibility with other additives), or heavy-metal-containing additives (residue
formation), sulfurized products show, in general, lower cost-effective side effects.

9.6 MANUFACTURE AND MARKETING ECONOMICS

9.6.1 MANUFACTURERS

Afton, United States

Arkema, France

DAI Nippon Inc., Japan

DOG-Chemie, Germany

Dover Chemical Corp., United States

Elco, United States

Harrison Manufacturing Company, Australia

Hornett, United Kingdom

TABLE 9.7

Esters, Synergistic Effect on EP and AW

Sulfurized Olefi n 40%

S, 36% active

TMP

Oleate

Four-Ball Weld Load

DIN 51350 Part 2

(N)

Four-Ball Wear

Scar DIN 51350

Part 3 (mm)

1.5% — 2800 0.8

— 5.0% 800 0.6

1.5% 3.5% 3200 0.55