Lubricant Additives

234 Lubricant Additives: Chemistry and Applications

N

N

H

N

H 3 C

N

N

O

O

R 2

R 1

R 4

R 3

N

R 2

R 3

R 1 O

B

OR 5

OR 4

STRUCTURE Q (TTZ) STRUCTURE R (SHDZ) STRUCTURE S (BHPD)

Both BZT and TTZ derivatives are also effective copper deactivators at low concentrations.
Therefore, these types of additives indeed have dual functions. They fi nd applications in industrial
oils, greases, and fuels.
Table 8.2 lists a prototype engine oil formulation used for the evaluation of ODZ additives where
various ODZs can be blended at 1 wt% in place of the same amount of light base oil. Table 8.3 lists
the Four-Ball Wear performance data where a series of ODZs were evaluated against 0.5 wt% and
1 wt% ZDDP. As demonstrated, those ODZ additives exhibited fairly good antiwear properties in
this bench test [86].

8.2.7 ADDITIVES WITH MULTIPLE ELEMENTS

Complex additives with multiple elements can be derived from various S/P, sulfur/nitrogen,
phosphorus/nitrogen, and many other traditional additive building blocks. As a result, molecules
with more than four, fi ve, six, or even more elements are created (S/P/N/B in addition to C/H/O).
Derivatization frequently adds a degree of complexity, yet provides a chance of achieving better
synergisms among all critical elements that can not only satisfy the performance needs but also help
neutralize any potentially added costs associated with the new chemistry under development.
Many examples are available in the literature as well as in the marketplace, such as
amine salts of dithiophosphates and thiophosphates (Section 8.2.5.2); borated derivatives of
dithiophosphates [41], dithiocarbamates [50], and dimercapto-thiadiazole [93]; urethane deriva-
tives of dithiophosphates [94] (Structure T); and reaction adducts of dialkyl phosphites, sulfur,
and acylated amines [95].

RO P S

OR′

C NH

S

NH C

CH 3

O

R O O

O R

S

P

S

OR

OR′

STRUCTURE T

Several complex additives have different chemistries involved with the same element in a single
molecule to attain strong synergisms. As exemplifi ed in the following case, where both phosphite
chemistry and phosphate chemistry are incorporated into the same molecule, greater antiwear
performance can be achieved ([96]; reaction 8.38).