NLGI
New Orthophosphoric Ester with Excellent Anti-Wear
and Heat Resistance Performance
Kenji Yamamoto, Kazuhiro Umehara, and Noriyoshi Tanaka, Surface Specialties Department, Functional Chemicals
Development Laboratory, ADEKA Corporation, 7-2-34 Higashi-ogu, Arakawa-ku, Tokyo 116-8553, Japan
Presented at NLGI’s 79th Annual Meeting, June, 2012, Palm Beach, florida, USA
Introduction
Table 1
Substance data of new compound
B
oth
haveenvironmental
made reducing
andenergy
economic
consump
concerns
Acid
P Ester A P Ester B
TCP
Phosphate
tion an important issue for engine and other
machine manufacturers. For lubricants, LowP conc. (%)
9.1
11
8.6
11
SAPS (less ash, less phosphorus and less sul
KVat4O°C
15•0
fur contents), more oil robustness and cease
D at 25°C
1.3
I 1.3 I 1.2
1.0
less energy savings with lower costs compared
Acid Value
to conventional ones are being desired.
Pour Point
-17
-40
Several methods can be used to reduce
energy consumption. Downsizing with higher
power to save energy consumption, which focuses
Anti-wear performance
on reducing a machine’s weight, is one of the most
important techniques. However, as each part becomes
The typical substance data compared in this study
smaller, contact pressure of the friction area and the
is listed in Table 1. Phosphorus concentration (%),
temperature of frictional parts tend to become higher.
Kinematic Viscosity at 40°C (mm2/s), Density at 25°C
It is desirable to decrease the dosage of phosphorus
(g/cm3), Acid Value (mg KOH/g) and Pour Point (°C)
containing anti-wear agents to prevent damage to
are listed.
frictional parts because of the requirement for low-SAPS.
Friction performance tests are conducted using an
Although No-SAPS additives are very attractive, it will
SRV reciprocating test machine shown in Rgure 1 and
be required in most cases to change hard-wear in the
Figure 2.
lubricating system for example, materials, processes
and/or running conditions, because the wear prevent
ing mechanism of them will be very different from ash
containing additives. Low dosage of new ash-containing
additives, on the contrary, is practical when lubricating
—
systems were not changed drastically.
Figure 2— Test specimens
Previous studies has shown that some phosphorus
•
•
ester can prevent wear even at low dosage and that
ester doesn’t have any defects in hydrolytic stability,
thermal stability and corrosion issues that conventional
phosphoric additives have.[1]
This paper describes frictional property and thermal
stability of some newly developed phosphorus esters,
compared to conventional anti-wear additives like tn
cresyl phosphate (TCP) and acid phosphate.
Figure 1 Appearance of SRV test apparatus
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I
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VOLUME 77, NUMBER 4
LGI
Base-oil
*
0.98mm
7~Il
~ +
P Ester A (0.1
0.56mm
+
P Ester B (0.1~
0.58mm
Table 2 describes friction test conditions
that demonstrate anti-wear performance
by SRV.
Test base-oil in this study was highly
refined mineral oil (Group-3, 4.2mm2/s at
100 degree-C).
Wear Scars of the ball after friction tests
are shown in Figure 3. It can be seen that
P Ester A and P Ester B containing oils
have excellent anti-wear performance. Wear
scars on the ball after testing were hardly
observed. TCP had little beneficial effect on
wear compared to the base oil test result.
Acid phosphate prevented wear better than
TCP but not to the extent of Ester A or
Ester B.
Figure 4 shows the corresponding fric
tion measurements on the same testing
oils. Friction coefficients roughly correlated
to the diameter of the wear scar and P
Ester A containing oil lead to the lowest
friction. This probably reflects more efficient
adsorption of P Ester A to the metal surface
than the other additives.
Heat resistance performance
+TCP(0.1 mass%)
0.77mm
Acid Phosphate
(0.1 mass%)
+
0.67mm
Figure 3 Wear scar and their diameter on tested ba
Thermal stability is evaluated using Thermo
gravimetry analysis (TG). Temperature is
elevated by 2 C per minute in Nitrogen
gas. 5% and 50% weight decreasing tem
perature was calculated from the TG curve
to compare the thermal stability of these
agents. Flash point obtained by open cup
tester (ASTM D92) has also been com
pared. Comparison of heat resistance per
formance is listed in Table 3.
P Ester A gives the highest thermal sta
bility in those chemicals. P Ester A did not
decrease until over 300°C. Even conven
tional additives started decreasing around
200°C. Remarkable thermal stability of P
Ester A and P Ester B is also indicated by
their Flash point which is far higher than
TCP and acid phosphate.
-43NLGI SPOKESMAN, SEPTEMBER/OCTOBER 2013
NLGI
Health and environmental hazards
0.20
P Ester A and P Ester B are physically stable and no
chemical groups are present in their molecules asso
ciated with corrosiveness, which are present in Acid
Phosphate. Any data which indicates health hazards
has been obtained. Furthermore, aquatic toxicity of
P Ester A and P Ester B are relatively lower than TOP’s.
As a result, they are not classified in any hazard cat
egory of GHS.
_____
______
________________
IBase~
+TCP~
+Acid Phosphate
0.15
C)
0
0
C
0
~
o.os
U-
0.00
0
Summary
20
40
60
80
100
120
Test Duration (mm.)
The tribological characteristics and thermal stability of
newly developed orthophosphoric esters have been
studied. It has been shown that a significant reduction
of wear can be obtained even at low dosage, by devel
oped additives, especially P Ester A.
P Ester A has the possibility to formulate new
Low-SAPS and be applied to lubricants for extremely
high temperature tolerance.
—
Base oil
P Ester A (0.1 mass%)
P Ester B (0.1 mass%)
TCP (0.1 mass%)
Acid Phosphate (0.1%)
Figure 4 — comparison of SRV friction performance of additive
containing oils and base oil.
Table 2
Friction test condition of SRV
Parameters
Conditions
Load
300N (max. 3.1 GPa)
Amplitude
4.0mm
Frequency
20Hz
Test duration
1 20mm.
Test temperature
80 degree-C
Test specimen
SUJ-2 (AlSl-52100)
High Carbon Chromium
Bearing Steel (760HV)
Reference
[1] Tanaka, N., Umehara, K., Yamamoto, K., New
Orthophosphorus Additive with Excellent Anti-Wear
Performance, 23~’ ELGI Annual Grease Meeting, Paris,
May2011
Table 3
Heat resistance performance
Additive
5% Loss
50% Loss
Name
Temp.
Temp.
P Ester A
350°C
430 C
•1•
P Ester B
380°C
TCP
230°C
290°C
Acid Phosphate
-44VOLUME 77, NUMBER 4
Flash
Point
334°C
..
282°C
154°C
NLGI
ABOUT THE AUTHORS
Kenji Yamamoto ADEKA Corporation
Mr. Yamamoto is a research techni
cian in the Lubricants Dept. of ADEKA
Corp. He joined Asahi Denka Co., Ltd.
(now ADEKA) in 2005, and has since
conducted research in anti-oxidants,
anti-wear agents and friction modifiers.
Kenji received his Masters degree in
Engineering in 2005 from Shinshu Univ.,
Nagano, Japan. Member Japanese
Society of Tribologists.
Noriyoshi Tanaka
ADEKA
Corporation
Tanaka graduated in
Chemical Engineering from the Uni
versity of Chiba in 1973. He is the
recipient of the Japan Petroleum
Institute Award for his paper ‘The
Development and Industrialization
of Molybdenum Dithio Carbamate in
1995. Member Japanese Society of
Tribologists.
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Statement of Ownership, Management, and Circulation
Publication Title: NLGI Spokesman
Publication No. 9331 -900
Filing Date: 10/30/2013
Issue Frequency: Bi-Monthly
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Annual Subscription Price: $65.00 Domestic, $109.00 International
Kazuhiro Umehara
ADEKA
Corporation Mr. Umehara graduated
in Faculty of Agriculture from Shizuoka
University. He has worked in the lubri
cant section at ADEKA since 1998.
He is currently Manager of Research
and Development for lubricating addi
tives including friction modifiers, anti
oxidants and anti-wear agents.
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Date
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