Preparation of additive package for gear lubricants and determination of tribological properties

Article abstract of DOI:10.1134/S0965544116020109

In this study an extreme pressure and anti-corrosion additive package for gear oils has been created. In this context three different organic molecules were synthesized. Methylene-bis (dibutyldithiocarbamate), Sulfured oleic acid and o,o-Dialkyldithio Phosphate. Mass spectrums and Elemental analyses were carried out for these three molecules. For each molecule 4-ball weld points (WP), 4-ball Wear Scar Diameter (WSD), Copper corrosion (CC) and salt spray tests (SS) were carried out. Antioxidant properties of synthesized molecules were determined. According to the test results eight different additive packages were prepared and WP, WSD, CC and SS tests were applied to each package to determine a suitable package content. The highest yield was obtained in the five and six additive package with 250, 300 kg weld point and 0.41, 0.53 mm scar diameter respectively. For all additive packages the extreme pressure and corrosion resistance properties of gear oil increase by increasing the percentage of Methylene-bis (dibutyldithiocarbamate). o,o-Dialkyldithio Phosphate showed the highest antioxidant activity and it has been obtained bets corrosion protection with Sulfured oleic acid.

Full text of DOI:10.1134/S0965544116020109

ISSN 0965ꢀ5441, Petroleum Chemistry, 2016, Vol. 56, No. 2, pp. 175–180. © Pleiades Publishing, Ltd., 2016.
Preparation of Additive Package for Gear Lubricants
1
and Determination of Tribological Properties
a, b,
a
Mustafa Akin * and Nalan Tekin
a
Department of Chemistry, Kocaeli University, Kocaeli, 41380, Turkey
TARIMSAN TARIM SAN. and TIC. A.S, Istasyon Mah. Beyazit Cad. No/24, Kocaeli, 41410, Turkey
eꢀmail: mustafa@tarmond.com
b
*
Abstract—In this study an extreme pressure and antiꢀcorrosion additive package for gear oils has been creꢀ
ated. In this context three different organic molecules were synthesized. Methyleneꢀbis (dibutyldithiocarꢀ
bamate), Sulfured oleic acid and o,oꢀDialkyldithio Phosphate. Mass spectrums and Elemental analyses were
carried out for these three molecules. For each molecule 4ꢀball weld points (WP), 4ꢀball Wear Scar Diameter
(WSD), Copper corrosion (CC) and salt spray tests (SS) were carried out. Antioxidant properties of syntheꢀ
sized molecules were determined. According to the test results eight different additive packages were prepared
and WP, WSD, CC and SS tests were applied to each package to determine a suitable package content. The
highest yield was obtained in the five and six additive package with 250, 300 kg weld point and 0.41, 0.53 mm
scar diameter respectively. For all additive packages the extreme pressure and corrosion resistance properties
of gear oil increase by increasing the percentage of Methyleneꢀbis (dibutyldithiocarbamate). o,oꢀDialkyꢀ
ldithio Phosphate showed the highest antioxidant activity and it has been obtained bets corrosion protection
with Sulfured oleic acid.
Keywords: Additive package, extreme pressure, 4ꢀball, gear oil, synthesis
DOI: 10.1134/S0965544116020109
1
A lubricant performs some of important functions. fins [4, 5]. Phosphate esters have been using as lubriꢀ
These include lubrication, cooling, cleaning and susꢀ cant additives earliest of 1920s. Selection of substituꢀ
pending, protection against corrosion, wear and fricꢀ ents considerable in phosphate esters to give optimum
tion. Lubricant include a base fluid and an additive
package. Base fluid’s mainly duty is lubricating and
carry to additives. The function of additives is either to
enhance an alreadyꢀexisting properties or to add a new
property [1]. As a result lubricants have varies properꢀ
ties differs from one to the other depending on the
intended use. Like Hydraulic, Slide way, Turbine,
Quenching, Gear and Motor oils.
An additive package should have antiꢀwear, corroꢀ
sion protection, cleaning, antiꢀfoam and lubrication
properties within. Especially the mechanical effiꢀ
ciency by reducing the friction further results in
decreased fuel consumption and results in energy savꢀ
ings. These depend on the content of additive package
with various extreme pressure (EP) and antiꢀwear
performance to lubricant [6]. There is many study on
the use of phosphorodithioic acid esters in lubricating
oils. Alkyl esters of phosphorodithioic acids, amine
dithiophosphates and other novel dithiophosphate
esters are reported as AW and EP additives [7, 8]. Sulꢀ
fur and Nitrogen containing are used to provide proꢀ
tection against moderate to high pressure, metal to
metal contacts in boundary lubrication, open chained
and heterocyclic compounds have been studied in
many research to found their AW properties. Dithioꢀ
carbamates are most widely used near organic sulfonic
acid ammonium salts [9] and alkyl amine salts of thioꢀ
cyanic acid [10].
In the present work it has been synthesized three
organic molecule; Methyleneꢀbis (dibutyldithiocarꢀ
bamate), Sulfured oleic acid and o,oꢀDialkyldithio
(
AW) additives [2]. The distinction between AW and
EP additives is not clear. Some are classed as AW in
one application and EP in another, and some have
both AW, EP and Antioxidant properties. This addiꢀ
tives classified by their element contents, sulfur addiꢀ
tives are probably the earliest known, widely used EP
compounds in lubricants. Sulfurization by addition of
elemental sulfur to fatty acids known as sulfurized fatty
acid esters [3] and to olefins known as sulfurized oleꢀ
13
31
Phosphate. Using H NMR, C , P and Elemental
analysis chemical structure of molecules were deterꢀ
mined. After that AW, EP, Antioxidant and Antiꢀcorꢀ
rosion properties for each molecule were determined.
According to the obtained results eight additive packꢀ
ages created which have different rates of this moleꢀ
cules. Finally performance tests were applied for each
package to determine true additive package.
1
The article is published in the original.
175

176
AKIN, TEKIN
Table 1. Physical properties of used additives
Additives
Elemental analysis (%)
Yield (%)
Solubilitya
Synthesized
C
N
H
S
Me t h yl e ne ꢀbi s (d ibu t yl d it h i ocar bama t e )
o,oꢀDialkyldithio Phosphate
Sulphurised oleic acid
7 8. 6
54. 42
46.67
NA
7 . 43
8. 73
7.31
NA
NA
NA
S ol
Sol
Sol
82.35
94.25
<1
NA
30.26
Commercial
Methyleneꢀbis (dibutyldithiocarbamate)
o,oꢀDialkyldithio Phosphate
Sulphurised oleic acid
NA
NA
NA
54.55
51.25
NA
7.09
8.82
7.88
NA
NA
NA
So l
Sol
Sol
<1
NA
29.81
a
Solubility at a concentration of 3 wt % in base oil.
NA: Not Analysed.
1
. SYNTHESIS OF MOLECULES
.1. Materials
water were mixed in an autoclave and the mixture was
cooled to 5 C. Maintaining stirring Carbon disulfide
was slowly added to the cooled mixture. The temperaꢀ
ture was controlled by an effecting cooling system and
°
1
Commercial Metyleneꢀbis(dibutyldithiocarbamꢀ it was not allowed to raise above 15°C. Then Methylꢀ
ate), o,oꢀDialkyldithio Phosphate and Sulfured oleic ene dichloride were added and the mixture slowly
acid purchased from Vanderbilt Chemicals, LLC. For heated. After alkylation the excess of Methylene
the synthesis of equivalent molecules Phosphorus seqꢀ dichloride was distilled off at normal pressure. After
uisulphide and sulfur purchased from SigmaꢀAldrich, that mixture cooled to the 40°C which resulted sepaꢀ
n
ꢀbutanol, diethyl fumarate, hydroquinone, benzene, ration of a mixture in to an aqueous and organic phase.
sodium carbonate, sodium sulfate, sodium hydroxide, The organic phase was further distilled in vacuum and
dibutyl amine, carbon disulfide, methylene dichloꢀ organic phase was washed with water three times.
ride, oleic acid and Sodium chloride purchased from
Merck. Group I base oils purchased from local refinꢀ
ery Turkish Petroleum Refineries Co. For the determiꢀ
nation antioxidant properties of synthesized commerꢀ
cial molecules, DPPH, methanol and nꢀbutanol purꢀ
chased from Merck.
Sulfured oleic acid was synthesized according to
the Horodysky et al. (1985) [14] briefly modifications.
Oleic acid and sulfur were charged to a glass reactor.
Mixture was heated to 180
sphere for 2 hours. The temperature was lowered to
45 C and air replaced the nitrogen atmosphere. And
filtered through diatomaceous earth at 100 C.
°C under nitrogen atmoꢀ
1
°
°
1.2. Synthesis Procedures
O,Oꢀdibutyldithiophosphate synthesized in two
step, first O,Oꢀdibutyl dithiophosphoric acid syntheꢀ
sized according to the Colclough et al. (1997) [11]
briefly modifications. Phosphorus sequisulphide and
sulfur were heated in refluxing nꢀbutanol for 2 hours at
1.3. Base oil and Additives Properties
The base stock used in the test is a paraffin base oil
(
Group I, SN 150; Kinematic viscosity 5.35 at 100
and 31.25 at 40 C, SN 500; Kinematic viscosity 10.5
at 100 C and 96.54 at 40 C). Three different additives
°C
°
°
°
1 °C. Second step, O,Oꢀdibutyl dithiophosphate
10
synthesized according to the Cassaday et al. (1950)
12] briefly modifications. A mixture of O,Oꢀdibutyl
diyhiophosphoric acid, diethyl fumarate and hydroꢀ
quinone was heated at 65 C for 24 hours, than allowed
were synthesized and their commercial equivalents
were analyzed together to compare their activities in
base oil.
[
°
to cool the room temperature. The reaction mixture
was taken up in 300 cc. benzene, washed with 10%
sodium carbonate solution and with water. The
organic layer was dried over anhydrous sodium sulfate,
filtered and concentrated in vacuo.
1
.4. Preparation of Tested Gear Oil Formulations
Base oil, synthesized molecules and commercial
molecules analyzed concentrate to determine antiꢀ
wear properties content of additive package. Accordꢀ
Methyleneꢀbis (dibutyldithiocarbamate) syntheꢀ ing to the test results it has been decided to rate of
sized according to the Jover et al. (1998) [13] briefly using additives in package. Eight different packages
modifications. Sodium hydroxide, dibutyl amine and created by using additives in different concentrations
PETROLEUM CHEMISTRY Vol. 56
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2016

PREPARATION OF ADDITIVE PACKAGE FOR GEAR LUBRICANTS
Table 2. Content of the created additive packages
Package Package Package Package Package Package Package Package
177
Additives %
1
2
3
4
5
6
7
8
Base oil (SN 150)
25
25
25
25
25
25
25
25
Synthesized
Methylenebis dibutyldiyhio carbamate
o,oꢀDialkyldithio Phosphate
Sulphurised oleic acid
35
10
30
–
–
–
20
30
25
–
–
–
30
40
5
–
–
–
5
35
35
–
–
–
Commercial
Methylenebis dibutyldiyhio carbamate
o,oꢀDialkyldithio Phosphate
Sulphurised oleic acid
–
–
–
35
10
30
20
30
25
–
–
–
30
40
5
–
–
–
5
35
35
(
Table 2). The gear oils in SAE 80Wꢀ90 grade created Model SF/100 test machine. Salt solution prepared by
by using this additive packages, dissolving 5 ± 1 parts by mass of sodium chloride in
pour point depressant and viscosity index modifier 95 parts of water. The compressed air supply to the
were analyzed according to the Turkish Standard TS nozzle for atomizing the salt solution maintained
2
ISO 11485 [15]. Finished SAE 80Wꢀ90 grade oil has between 69 and 172 kPa/m . The test specimens conꢀ
1
33 cSt viscosity at 40
°
C, 14.6 cSt at 100
C flash point.
°
C, 105 visꢀ sist of steel meeting the requirements of ASTM D 609
cosity index, –27 C pour point, 215
°
°
washed with sample and dried in room temperature
before the test.
Copper corrosion test, according to the ASTM D
30 [20] for 3 hours at 100°C, applied to the all addiꢀ
1.5. Tribological Properties
1
The antiꢀwear properties of synthesized molecules, tives and packages. The test carried out with a SETA
commercial molecules and additive packages were Copper/Silver Corrosion Bath 11400ꢀ6 model test
analyzed by 4ꢀball Wear Scar Diameter (ASTM machine.
D4172) [16] and 4ꢀball Welding Points (ASTM
D2783) [17] which were examined on a 4ꢀball tester
2. RESULTS
(
SETAꢀShell 4ꢀball test machine) in room temperaꢀ
ture, at 1600 rpm rotating speed, at 50 kgf load and
steel balls with diameter of 12.7 mm.
Physical properties of synthesized and commercial
additives shown on Table 1. It can be seen clearly that
synthetic additives yields ranged from 78.6% to
9
4.25%. All additives have different rate of elements
1.6. Antioxidant Properties
because of their structural natures. Commercial addiꢀ
2
,2ꢀdiphenylꢀpicrylhydrazyl (DPPH) free radical tives and synthetic ones have the similar values of eleꢀ
scavenging activities of synthesized molecules were mental % contents. All additives can soluble in parafꢀ
determined according to the Ferreira et al. (2009) [18]. finic base oil.
An aliquot (1 mL) of appropriately diluted solutions of
It has been shown on Table 2 content of the created
⎯
5
molecules were mixed with 2.7 mL 6.10 M DPPH packages. Created SAE 80Wꢀ90 grade samples tested
solution. Samples were kept for 1 h at room temperaꢀ to determine tribological properties of the syntheꢀ
ture and then the absorbance was measured at 517 nm. sized, commercial additives and created packages. For
The percentage of absorbance inhibition (I %) at 517 each sample it has been used two different rate from
nm was calculated using the equation of: I % = [(Ablank additive package 1% and 1.8 % to determine 4ꢀball
–
Asample)/Ablank
]
×
100.
WSD and 4ꢀball WP values. According to the results
for both synthesized and commercial additives, the
best values obtained with Methyleneꢀbis (dibuꢀ
tyldithiocarbamate) 0.59 mm WSD value and 300 kgf
1.7. Antiꢀcorrosion Performances
All additives and packages tested according to the WP value for 1.8% addition of synthesized product
ASTM B 117 [19] standard (Salt Spray Test) for and 0.54 mm WSD value and 250 kgf WP value for
20 hours at 35+ 1.1 – 1.7 C with a CW Salt Spray 1.8% addition of commercial product. Second best
1
°
PETROLEUM CHEMISTRY Vol. 56
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2016

178
AKIN, TEKIN
Table 3. Friction values from standard 4ꢀball WSD and 4ꢀball WP of additives and additives packages in SAE 80Wꢀ90 grade
lubricant
Additives
4ꢀBall WSD (mm)
4ꢀBall Welding Additives (kgf)
Synthesized
1 wt %
1.8 wt %
1 wt %
1.8 wt %
Methylenebis dibutyldiyhio carbamate
o,oꢀDialkyldithio Phosphate
Sülphürised oleic acid
0.67
0.78
0.82
0.59
0.66
0.76
250
200
300
250
<200
<200
Commerical
Methylenebis dibutyldiyhio carbamate
o,oꢀDialkyldithio Phosphate
Sülphürised oleic acid
0.62
0.66
0.83
0.54
0.58
0.74
250
200
200
250
250
200
Packages
Package 1
Package 2
Package 3
Package 4
Package 5
Package 6
Package 7
Package 8
0.54
0.51
0.68
0.58
0.53
0.43
0.86
0.84
0.48
0.49
0.68
0.51
0.53
0.46
0.78
0.81
250
250
300
300
200
200
<200
250
200
300
250
250
<200
<200
<200
<200
SN 150 base oil (without additives)
0.88
150
value obtained with synthesized and commercial o,oꢀ
Results which are obtained with additive packages
Dialkyldithio Phosphate and last one with Sulfured showed that, best value was obtained with package 6
oleic acid.
which created with commercial additives for 1.8 addiꢀ
Sulfured oleic acid, S
Sulfured oleic acid, C
90
80
70
60
50
40
30
20
10
0
Methyleneꢀbis Dibutyldithio
carbamate, S
Methyleneꢀbis Dibutyldithio
carbamate, C
o,oꢀDialkyldithio Phosphate,
S
o,oꢀDialkyldithio Phosphate,
C
SIM 150 base oil
0.2
0.4
0.8
mg/mL
1.0
1.8
S: Synthesized C: Commercial
DPPH scavenging activity (% Inhibition) of synthesized and commercial Additives.
PETROLEUM CHEMISTRY Vol. 56
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2016

PREPARATION OF ADDITIVE PACKAGE FOR GEAR LUBRICANTS
179
tion of package to the SAE 80Wꢀ90 grade product, revealed the same truth. On the other hand all samples
with 0.43 mm WSD value and package 1, 2, 4, 5, 3, 7, passed the Copper Corrosion test without Sulfured
8
respectively, followed it. The results showed that oleic acid synthesized and commercial samples
highest Methyleneꢀbis (dibutyldithiocarbamate) conꢀ because of the high active sulfur content.
tent effected the results mainly and highest o,oꢀ
Dialkyldithio Phosphate content secondly. For the
4
. CONCLUSIONS
Welding results for both packages 1, 2 and 5 obtained
00 kgf Welding value. It is clearly seen on this results
3
In this study it has been investigated tribological,
antiꢀcorrosion performances and antioxidant activiꢀ
ties of three synthesized additives and their commerꢀ
cial equivalent additives. According to the results it has
Methyleneꢀbis (dibutyldithiocarbamate) has more
effect on WP results than the others additives
(
Table 3).
Antioxidant properties of synthesized and comꢀ been created eight different additive packages which
mercial additives were determined in different conꢀ are obtained from a mixture of these three contribuꢀ
centrations. Among both synthesized and commercial tions. All packages tested according to the ASTM
additives the highest DPPH Scavenging effect was standards do determine their effects as a gear oil addiꢀ
obtained with 91.09% and 89,05% at 1.8 mg/mL conꢀ tive. These test results showed that, Methyleneꢀbis
centration for o,oꢀDialkyldithio Phosphate. Methylꢀ (dibutyldithiocarbamate) is the best AW and EP addiꢀ
eneꢀbis (dibutyldithiocarbamate) showed better antiꢀ tive alone, o,oꢀDialkyldithio Phosphate has the highꢀ
oxidant activity than Sulphurised oleic acid for both est antioxidant activity and Sulfured oleic acid is the
synthesized and commercial additives (figure).
best antiꢀcorrosion agent for gear lubricants. On the
According to the ASTM B 117 test results without other hand, eight different additive packages because
Sulfured oleic acid all samples failed the test. Only of their different rates of additives contents showed
Sulfured oleic acid passed the test for both synthesized different results. Package six and five showed very good
and commercial samples. Sulfur is an important comꢀ AW and EP properties in the gear lubricant with their
ponent of the antiꢀcorrosion additive packages for high Methyleneꢀbis (Dibutyldithiocarbamate) and
many years in lubricants and these results once again o,oꢀDialkyldithio Phosphate content.
S
H C (H C)
O
3
3
2
P S H
+
H2S
2
P S + 8CH –(CH ) –OH
4
2
5
3
2 3
H C (H C)
O
3
2
3
O
O
S
H C (H C)
O
3
S
3
2
H C (H C)
O
3
3
2
P S CH
O
CH
+
H C
O
CH
HC
P
S H
3
H C (H C)
O
CH2
3
2
3
O
CH3
H C (H C)
O
3
O
CH3
3
2
O
O
Schema 1. Synthesize mechanism of O,OꢀDibutyldithio Phosphate.
S
C H
C H
4 9
4
9
NH + CS
+ NaOH
N C S Na + H O
2
2
C H
4
C H
4 9
9
S
S
S
C H
C H
4 9
4
9
C H
4
9
2
+ 2NaCl
N C S Na + CH Cl2
2
N C S CH2 S C N
C H
4
C H
4 9
9
C H
4
9
Schema 2. Synthesize mechanism of Methyleneꢀbis(dibutyldithiocarbamate)
O
O
H3C
CH CH
C OH
7
7
H C CH CH
C OH
+
S
S
S
3
7
7
H C
7
C
C
7
C OH
O
3
Schema 3. Synthesize mechanism of sulfured oleic acid.
PETROLEUM CHEMISTRY Vol. 56
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2016

180
AKIN, TEKIN
ACKNOWLEDGMENTS
This work was supported by TUBITAK (Project
no. 7100748). This work was supported in part by the
TARIMSAN TARIM SAN. ve TIC. A.S. and Univerꢀ
sity of KOCAELI.
8. D. E. C. Corbridge, Biochem. Technol.
7, 213 (1985).
9. D. S. Bosinack, US Patent No. 4079012 (1978).
1
1
0. J. W. Nebzydoski, US Patent No. 3952059 (1976).
1. T. Colclough, US Patent No. 5703262 (1997).
12. J. T. Cassaday, US Patent No. 2578652 (1950).
1
1
1
3. B. Jover, US Patent No. 5744629 (1998).
4. G. A. Horodysky, US Patent No. 4,549,974 (1985).
5. TS 11485, Turkish Standard: Lubricating oils, indusꢀ
trial lubricants and related products (Class L)ꢀGroup
G: Gear oils—Used in motor vehicles, June 2012,
ICS 75.100.
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