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9.7.2 INDUSTRIAL APPLICATIONS
Multifunctional and multipurpose lubricants are on the wish list of many end users. The development
for sulfurized products that can be used in these types of lubricants is in full progress, and the products
have already been commercialized. Mainly light-colored products based on mixed, well- balanced
raw materials to ensure a broad performance range are used for multipurpose applications.
Replacement of heavy metals and chlorinated paraffi ns in almost all industrial lubricants is
also an ongoing project that is widely found in the lubricants industry. Sulfur carriers are playing a
predominant role as substitutes for these products.
Increasing demands for environmentally more acceptable lubricants has led many formulators
into the development of lubricants based on natural triglycerides such as canola oil, soybean oil, tall
oil, or esters. Biodegradable sulfur carriers are used as EP and AW additives as well as secondary
AOs in these applications.
9.8 TRENDS
9.8.1 CURRENT EQUIPMENT/SPECIFICATION
Sulfurized products are single components and not complete performance packages such as hydrau-
lic or crankcase packages. Therefore, sulfur carriers are used in the whole variety of lubricants
rather than in a specifi c equipment. Also, no national or international specifi cation standards exist
for these products. The manufacturer sets the specifi cation in agreement with the user.
9.8.1.1 Types of Equipment
As already mentioned, the biggest use of sulfurized products (excluding SIB) is in industrial appli-
cations. Metalworking and grease applications followed by industrial gear oils are formulated with
sulfur carriers. A lot of old equipment is still in use. Many mid-size and small companies have not
modernized their metalworking machines for more than three decades. This older, robust equip-
ment is very often running at low machining speeds and nonoptimized machining parameters.
Modern machining equipment requires thermally stable fl uids, based on highly refi ned or synthetic
base fl uids. Improved solubility in nonpolar oils and thermal stability of sulfurized products gain
importance.
9.8.1.2 Additives in Use
Today’s additive usage depends very much on regional technological requirements and local legis-
lation. In countries with low, old or standard technology and little environmental concerns, addi-
tives such as chlorinated paraffi ns or heavy metals are used for the formulation of lubricants, often
in combination with sulfurized products. In countries where legislation has put some pressure onto
the formulators and users of lubricants (higher disposal costs for chlorine-containing lubricants,
limits on heavy metals in waste water, etc.), sulfurized compounds play an even more impor-
tant role. They are the main EP additives, very often combined with sulfonates, salicilates, phos-
phoric acid esters, dialkyldithiophosphates, or carboxylic esters to complement AW and lubricity
performance.
9.8.1.3 Defi ciencies in Current Additives
All available sulfur carriers are limited in their thermal stability. This is a desired feature, because
reactive sulfur will only be released when the molecule breaks down. However, there are applica-
tions running at a high temperature, where a fast decomposition of the EP product is not desired.
Corrosion toward yellow metals is another defi ciency of sulf u r ized compounds. I n h igh- temperat u re
applications, the active sulfur will react with copper to form copper sulfi de.