GRANTED
10/2/2000
THE PATENTS ACT,1970
COMPLETE
SPECIFICATION
TITLE
"LUBRICATING OIL COMPOSITIONS FOR INTERNAL COMBUSTION ENGINES HAVING IMPROVED DETERGENCY CHARACTERISTICS AND HIGHER BIODEGRADABILITY "
APPLICANT
INDIAN OIL CORPORATION LIMITED, (A Govt, of India Undertaking), G-9,
Ali Yavar Jung Marg, Bandra (East),
Mumbai-400 051, India.
The following Specification Particularly describes and ascertains the nature of this invention and the manner in which is to be performed.

FILED OF INVENTION
This invention relates to lubricating oil compositions which exhibit marked improvement in the detergency characteristics resulting in lower engine carbon deposits and makes available an internal combustion engine oil package, both for gasoline and diesel engines, with substantial improvement in the biodegradability. More particularly, this invention is directed to lubricating oil compositions for internal combustion engines which contain a synergistic mixture of calcium phenate overbased detergent derived from cashew nut shell liquid (CNSL) and an amine salt of phosphorodithioic acid also derived from CNSL.
BACKGROUND OF THE INVENTION
Lubricant additives can be classified as materials that impart new properties to or enhance existing properties of the lubricant into which these are incorporated. The lubricant additives besides showing enhanced performance need to be cost-effective, easily manufactured and should have higher biodegradability.
Detergents, anti-wear and antioxidants constitute a major class of lubricant additives, which find application in engine lubricants especially for internal combustion gasoline and diesel engines. Among


the conventionally used detergents in lubricating oil additives are metallic sulphonates, phenates and salicylates. Metallic phenates and sulfurised metal the zinc additive, giving low ash lubricant formulation, the total removal of zinc has not been recommended as a practical proposition. US patent 4,330,420 disclosed the inclusion of synergistic amounts of dialkyldiphenyl amine antioxidant and sulfurised polyolefins to bring down the amount of zinc dithiophosphate. US patent 4,089,791 relates to a low ash mineral lubricating oil compositions comprising zinc dialkyldithiophosphate, overbased alkaline earth metal salts and a trialkanolamine compound as an additional anti-oxidant component to compensate for the reduced ZDDP. In US patent 5,916,850 and EP patent 0915097A1, we have disclosed the process for the preparation of various amine salts of phosphorodithioic acids, derived from cashew nut shell liquid, which when blended into lubricants provided effective anti-wear, anti-oxidant and friction reducing properties. Inclusion of these ashless dialkyldithiophosphates into the lubricant formulations for internal combustion gasoline and diesel engines, has resulted in reduction of ash content. These dialkyldithiophosphates, surprisingly, have shown a synergistic increase to the detergency action of CNSL derived sulphurised metallic phenate additives.


OBJECTS OF THE INVENTION
An object of this invention is to propose synergistic lubricating oil compositions for internal combustion gasoline and diesel engines, which exhibit higher detergency and lower ash content.
Another object of this invention is to propose lubricating oil compositions for internal combustion engines containing sulfurised overbased calcium phenates derived from cashew nut shell liquid and multifunctional additive based on amine salts of phosphorodithioic acids derived from cashew nut shell liquid resulting in higher oxidation stability, higher detergency, lower zinc and phosphorus content and higher biodegradability.
DETAILED DESCRIPTION OF THE INVENTION Component A
Overbased metallic sulphurised phenate detergent useful in this invention comprises a substance prepared by reacting phenates are one of the widely used detergents in lubricating oils, for mainly
internal combustion gasoline and diesel engines, and these function to neutralize acid substances, sludge etc., generated in engine. Thus, the metallic phenates, generally alkaline earth metal phenates, makes

it possible for engine parts, good protection from excessive corroding caused by acidic substances and prevent excessive wear caused by sludge. The overbasing of these phenates helps in fighting the acids produced during the combustion of fuel, while the sulfurisation mainly helps to improve heat stability.
The conventional method of making overbased metallic sulfurised phenates, useful as lubricating oil additives, involves reacting alkyl substituted phenols generally para-substituted, with sulphur, metal salts followed by carbonation. Thus, US patent 2,370,302 discloses the use of sulphurised phenates in lubricating compositions which are subjected to higher temperatures. Similarly, US patent 3,367,867 discloses the use of sulfurised overbased calcium phenates as detergents in lubricating oils for internal combustion engines. US patent 4,874,007 discloses a process for preparation of sulphurised alkyl-substituted phenates to be used as detergents. In US patent 5,910,468, we have already described a process for the preparation of calcium phenate detergents derived from naturally occurring & biodegradable cashew nut shell liquid. It was surprisingly discovered that overbased calcium

phenates derived from cashew nut shell liquid had low viscosity at high basicity, good oil solubility and higher biodegradability. These phenates could be prepared in economically advantageous manner and showed remarkably good detergency.
The anti-wear protection and protection against oxidation at high temperature to a lubricating oil used in internal combustion engines is generally met by addition of metallic dialkyldithiophosphates. However, these metallic dithiophosphates contribute to the total ash content of the lubricant composition. Since the zinc is a source of sulfated ash and phosphorus is a poison for catalytic converters, the art has sought to reduce both Zn & P from the lubricating oil compositions (see US patents 4,147,640, 4,330,420 and 4,639,324). While the prior art has been successful in reducing distilled or hydrogenated distilled CNSL with calcium hydroxide or oxide, and sulphur, in the presence of co-surfactants and mineral oil, and carbonation of the resulting reaction mixture.
In preparation of the overbased sulphurised overbased calcium phenates of the present invention, CNSL is employed as a naturally occurring biodegradable, cheap and abundantly available material. The overbased

detergent component of the present invention is easily & conveniently produced by a simple sequential reaction with sulphur, calcium oxide/hydroxide, followed by a step of overbasing with carbon dioxide, in the presence of cosurfactants. If required, the resulting basic sulphurised metal phenate can be subjected to further overbasification. By selecting various reaction conditions and processing steps it is possible to obtain overbased calcium phenate detergents derived from CNSL, fully soluble in lubricating oil base stocks, having a TBN in the range of 100-400 mg/KOH/g. The amount of component A in lubricant compositions of the present invention, for internal combustion gasoline and diesel engines, may range from 0.5 to 20% by weight of the total lubricant composition. However, the preferred range for lubricating oil meeting API SC/CC to SG/CD classification is 0.5 to 12 wt%.
Component B
Component B of the compositions of this invention is an anti-wear & anti-oxidant agent comprising of amine salts of phosphorodithioic acids derived from CNSL. The general procedure of synthesis of these additives consists of reaction of distilled CNSL or distilled hydrogented. CNSL with phosphorus

pentasulphide and the neutralization of resulting
phosphorodithioic acids with suitable amines. The
amount of this component in lubricant composition of the
present invention, for internal combustion gasoline and
diesel engines may range from 0.l to 10% by weight of
the total lubricant composition. Preferred range of
this additive for making lubricating oil meeting API
SC/CC to SG/CD grade of lubricating oils is 0.5 to 6
weight %. The amine part of component B is derived from
primary, secondary tertiary alkyl/alkylarylamines having
alkyl chain from C to C or mixtures thereof.
1 20
BIODEGRADABILITY TEST
The biodegradability tests of component A & B
were carried out in comparison to the commercial
additives, accordingly to CEC. L-33-A-93 protocol. In
the test procedure, flasks containing mineral media
with test sample and innoculum from the sewage plant
are incubated for 21 days. At the end of the test,
these flasks are extracted with organic solvent and
analysed by IR measurements. The biodegradability is
expressed as a percentage difference between test and
poisoned flask. The detergent component A of the
present invention exhibited about 20% more
biodegradability than the commercial phenates, while the


enhancement in biodegradability for component B was more than 100% vis-a-vis commercial ZDDP. The biodegradability data is shown in Table-1.

TABLE 1
Biodegradability Test Results on Component A & B as per CEC-L-33-A-93 Protocol

S.NO. Additive Component % Biodegradability
1 Component A 41.27
2 Commercial Phenate 1 32.10
3 Commercial Phenate 2 32.49
4 Component B 21.86
5 Commercial ZDDP 10.36
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OTHER COMPONENTS AND LUBE BASE STOCK
Other components used in the lubricating compositions of the present invention are (i) a dispersant, polyisobutylene succinimide type, commercially available from Lubrizol (LZ 890) or Infenium [SAP 210 & 240] or Ethyl [Hitec 644 or 646] or Chevron [Oloa 1200 & 3740]. These commercially available dispersants were used in the range of 2-12% in the lubricating compositions of the present invention; (ii) antioxidants, mixture of phenolic and aminic


antioxidants; commercially available additives include (Ethyl E-702) & (Irganox L-57) and present in an amount of 0.2 to 1.5%; and anti-wear additives of ZDDP type available from Lubrizol, LZ 1395 or LZ 1360 or Hitec 678 or LZ 677 and present in an amount of 0.3 to 1.8%. Commercially available viscosity index improvers such as ECA 8586, Paratone 8523 to TLA 3471 can be added to these base stocks as per need to obtain the lubricating oil of desired viscosity grade.
The lubricating oil base stock used for
preparing the composition of the present invention
include both mineral and synthetic hydrocarbon oils of
lubricating viscosity having a kinematic viscosity of 2

o to 40 cSt at 100 C. The mineral lubricating oils may be
paraffinic/ napthenic or asphaltic base, or mixtures
thereof. Typical synthetic oils used to prepare the
lubricating compositions of the present invention
include trimethylolpropane esters, neopentyl and
pentaerythritol esters, polyethylene glycol, bis (2-
ethylhexyl) adipate, bis(2-ethylhexyl)sabicate,
polyalphaolefins and phenoxyphenyl ethers.
The lubricating oil composition of the present invention with the synergistic combination of detergent (A) & aminothiophosphate component (B),


exhibits excellent heat stability, detergency compatibility with other additive components, lower costs, superior performance, lower ash content, ease of preparation and higher biodegradability. Moreover, these components are highly economical, since the basic raw materials of components A and B consist of naturally occurring, biodegradable, abundantly available and cheap cashew nut shell liquid (CNSL).
The examples of the compositions of the present invention, as given in Tables 2 & 3, are illustrative in nature, but without intending to imply any limitations thereon.
The efficacy of the compositions of this invention has been thoroughly evaluated by laboratory, rig and engine tests.
DETERGENCY PERFORMANCE-PANEL COKER TEST
The detergency efficacy of crankcase oils of
the present invention is assessed in term of deposit
forming tendency on rectangular A1-steel panel in Panel
Coker test. In this test, 200 ml of the test sample is
o taken in sump and heated at 100 C. For a period of 6
hrs, this heated oil is splashed by whiskers on A1-
steel Panel, the temperature of which is maintained afc:


o 300 C. After completion of test, deposits on panel are
weighed. The base fluid without any detergent additive
showed an increase in panel weight of 238.5 mg.
Incorporation of overbased sulphurised calcium phenates,
derived from cashew nut shell liquid of the present
invention, decrease the deposit of panel from 238.5 mg
to 25-35 mg, as compared to deposit of 45-70mg, when
conventional calcium over based sulphurised phenate
detergent are used at the equivalent concentrations.
This clearly demonstrates superior detergency action of
the product of the present invention. The compositions,
their physico-chemical characterisation and their
performance in the Panel Coker test are presented in
Tables 2 to 5.
ANTIOXIDANT PERFORMANCE-PRESSURE DIFFERENTIAL SCANNING CALORIMETRY (PDSC)
The PDSC (DuPont Model-910/1090B) was used
for relative antioxidant performance evaluation of the
composition. In this method, a test sample (10 mg) taken
in a sample boat was subjected to heating from 100-
o o
300 C. at the rate of 10 C. per minute under 500 psi
oxygen pressure. The onset of oxidation temperature was
adopted as a criteria for assessment of antioxidant
performance. In general, the increase in onset of

oxidation temperature indicates improvement in
antioxidant performance. The incorporation of
aminophosphorodithioates derived from CNSL, at 0.5-1.0%
level, increased the temperature of the onset of

o oxidation by 30-85 C, w.r.t. unformulated base oil. The
addition of 1-2% of overbased sulphurised calcium CNSL
phenate detergent of the present invention, to the
lubricating oil base stock also enhanced the onset of
o oxidation temperature by 25-65 C, which is indicative
of better antioxidant characteristics of the product.
Surprisingly, the combination of sulphurised
calcium CNSL phenate of the present invention and
aminophosphorodithioates derived from CNSL proved to be
synergistic in improving the antioxidant performance of
the lubricant composition. The combination of both CNSL
derived components increased the onset of oxidation
o temperature by 65-105 C. This synergistic composition
was incorporated to formulate the engine oil
composition, by incorporating other conventional
lubricating oil additives, i.e., metallic sulphonates,
polymeric succinimides, polymeric viscosity index
improvers, pour point depressants, corrosion inhibitors
and the like. The compositions, their physio-chemical
characterisation and their performance in the DSC test
are presented in Tables 2 to 5.


HOT OIL OXIDATION TEST
Hot oil oxidation test (HOOT) is a laboratory-oxidation test, in which air is bubbled at 10
litres/hour for 64 hours, in the test lubricant, at

o 160 C, in the presence of Cooper & Ferrous naphthenates
as catalysts. After the completion of the test, the %
change in the viscosity of the test lubricant is

o measured at 40 C. The lower change in the viscosity
indicates better oxidation resistance of the lubricant. In general, it was noticed that aminophosphorodithioates derived from CNSL improved the oxidation resistance of oil. Likewise, the calcium sulphurised CNSL phenates also improved the oxidation stability of the lubricants. The combination of the CNSL derived alkylaminophosphorodithioates and sulphurised phenates of the present invention, gave very selective results which were dependant upon the chemistry and length of the alkyl chain in CNSL alkylaminophosphorodithioates and percentage composition of the components in the lubricant composition. The compositions, their physio-chemical characterisation and their performance in the HOOT test are presented in Tables 2 to 5.
L-38 ENGINE TEST
The formulations of the present invention were evaluated for performance in engines having copper-


lead bearings by the Labeco L-38 test method, ASTM D 5119-90. This test is designed to evaluate crankcase lubricating oils for resistance to oxidation stability, corrosion, sludge and varnish when subjected to high temperature operation. When multigrade oils are tested, it also evaluates shear stability of the test oil. The procedure involves the operation of the single cylinder CLR oil evaluation engine under constant speed, air-fuel ratio and fuel flow conditions for extended duration (commonly 80 hours), subsequent to a break-in period of 4.5 hours. Prior to each run, the engine is thoroughly cleaned, pertinent measurements of engine parts are taken, and new piston, piston rings and copper-lead connecting rod bearing inserts are installed. Bearing weight loss data is obtained at 40 hours, and at the completion of the extended test duration.
At the conclusion of the run, the engine is disassembled and the performance of the oil is judged by the following: a) a visual examination of the engine for deposits; b) by the weight loss of the copper-lead bearings; c) and by comparing the periodic oil sample analysis with the new oil analysis. The results of this test are given in Table 6. As seen from the test results, the formulation based on overbased sulphurised calcium phenates, derived from cashew nut shell liquid passed this test with bearing weight loss lower or equal than conventional sulphurised calcium phenates.

MWM-B TEST METHOD FOR PISTON CLEANLINESS
The MWM-B test method employs the MWM KD 12 E single cylinder Diesel engine for the testing, and comparative assessment of engine lubricating oils in respect to piston cleanliness. This is a swirl chamber naturally aspirated engine with a swept volume of 0.85 litres. The running-in of the test engine is carried out with the test oil. Four sycles of 0.5 hours each are run, with increasing engine speed from 1200 to 2200 l/min at a constant output of 2.5 kw, followed by five further cycles of 1 hour each at a constant engine speed of 2200 1/min, whilst increasing the output from 3.7 to approximately 11 KW.
After completion of the test, the piston is removed and the rings are inspected for sticking. In accordance with this test method, an evaluation of the piston can only be carried out with completely free piston rings. The pistons are then visually assessed as per CEC L-12-A-76 rating method. All the formulations of the present invention, based on cashew nut shell derived calcium sulphurised phenate and aminophosphorodithioate showed rating between 66 to 70, which fall in the API CD (See Table 6). CLR-LTD TEST FOR SLUDGE & VARNISH DEPOSITS
CLR-LTD test is carried out to check the ability of oils to minimise the formation of undesirable deposits associated with intermittent light duty low temperature operating conditions when tested according


to the prescribed procedure. Piston skirt varnish, total engine varnish, total engine sludge, oil ring plugging and oil screen clogging are measured during the test. All the formulations of the present invention, based on cahsew nut shell derived calcium sulphurised phenate and aminophosphorodithioate showed rating well above the designated pass limits of the test (See Table 6)
TABLE 2

S.NO. Test Sample Panel Coker (Wt.Gain in mg) HOOT (%
visco-sity-increase DSC (increase in onset
of oxidation tempera-ture in °C
1 Base Oil (BO) 238.5 245 -
2 BO+Component A 1% 34.3 82 28.1
3 BO + Component (2%) 25.9 77 63.4
4 BO + Commercial Phenate (1%) 68.6 104 26.9
5 BO + Commercial Phenate (2%) 46.7 99 59.1
6 BO + Component B (0.5%) 204.5 79 45.3
7 BO + Component B (1%) 210.9 71 87.2
8 BO + Component A (1%)+ Component B (0.5%) 28.3 59 68.5
9 BO + Component A (l%)+ Component B (0.5%) 24.7 45 102.8

TABLE 3
Test Lubricant Formulation Compositions

Additive Component

FORMULATION

I II III IV V VI VII
Component A 1.0 2.0 2.0 2.0 2.0 3.0 -
Component B 0.5 0.5 0.8 1.0 1.0 0.8 -
Commercial Sulphonate Detergent 1.5 1.5 1.5 1.5 1.0 1.0 -
ZDDP 1.8 1.0 0.8 0.6 0.6 0.3 -
Antioxidant(A) mine/phenol) 1.2 1.2 1.5 1.5 1.5 0.2 -
Others containing esstantially viscosity index improvers and minor amounts of metal deacti¬vators, corrosion inhibitors fric¬tion modifier 26.8 24.8 24.7 23.9 8.0 0.5 17.4
Commercial Engine Oil Package (SG/CD level 11.6
Base Oil 67.2 69.0 68.7 69.5 85.9 94.2 71.0
*The formulations contained commercial VI Improver in different dosages, to impart the required viscometrics.
Commercial dispersant, PPD & metal deactivator were added to each formulation.

Table 4 Physico-chemical Characteristics of Lube Formulations


Table 5 Performance Evaluation of Formulated Compositions

Formula tions Panel Cokcr (Wt. Gain in mg) HOOT
(% viscosity
increase) DSC
(increase in onset of oxidation temperature in °C) Pour Ball Wear Scar Dia (mm) at 40 Kg load as per ASTM D-4172
I 43.7 76.0 65.6 0.45
II 40.3 70.4 70.5 0.45
III 36.5 65.3 77.5 0.45
IV 30.4 55.6 80.9 0.40
V 31.5 59.8 82.3 0.40
VI 44.9 77.9 78.4 0.50
1 VII 53.0 88.7 79.5 0.45
Table 6 PERFORMANCE EVALUATION OF LUBRICANT COMPOSITIONS-ENGINE JEST RESULTS

Name of Test

Lubricant Lubricant Specifications
composition composition
V VII

69.0
46.58 44.49 0 %
1. CRC L- 38 Engine 25.29 mg Bearing Wt. Loss
2. MWM - B Engine Overall Merit Rating
3. CRC - LTD Test

a) Sludge Rating
b) Varnish Rating
5 %
c) Oil Ring Slot
Plugging
d) Oil Screen
Clogging
10
e) Ring Sticking
Merit

27.92 mg Max. 50 mg
68.0 Min. 65 for CD
Min. 55 for CC
46.25 Min. 42
43.85 Min. 42
2.0% Max. 10%
8.0 % Max. 10%
8.5 Min. 7.5

CLAIMS;
1. A lubricating oil composition for internal combustion gasoline and diesel engines, comprising a major portion of an oil of lubricating viscosity and (a) a minor amount of sulphurised overbased calcium phenate detergent obtained from distilled hydrogenated CNSL; (b) a minor amount of an amine salt of phosphorodithioic acid, obtained from CNSL and having the following general formula:

and known activites 2. A lubricating oil composition as claimed in claim 1, wherein the lubricating base oil is a mineral oil such as paraffinic/ napthenic or asphaltic base, a synthetic oil or mixtures thereof, having a kinematic viscosity of 2 to 40 cst at 100°c.
3. A lubricating oil composition as claimed in claim 1, wherein the
component B is amine salt of phosphorodithioic acid obtained from
distilled CSNL.
4. A lubricating oil composition as claimed in claim 1, wherein the
component B is obtained from distilled and hydrogenated CSNL.


5. A lubricating oil composition as claimed in claim 1, wherein the amine part of component B is obtained from primary alky 1/alky laryl amines having alkyl chain from C1 to C20.
6. A lubricating oil composition as claimed in claim 1, wherein the amine part of component B is obtained from secondary alkyl/alky laryl amines having aklkyl chain from C1 to C20.
7. A lubricating oil composition as claimed in claim 1, wherein the amine part of component B is obtained from tertiary alkyl /alky laryl amines having alktl chain from C1 to C20.
8. A lubricating oil composition as claimed in claim 1, wherein the amine part of component B is obtained from a mixture of primary and/or secondary and/or tertiary alkyl/alky laryl amines having alky 1 chain from C1 to C20.
9. A lubricating oil composition as claimed in claim 1, wherein component A is present in an amount of 0.5 to 20%, and preferably, 0.1 to 12.0% w/w.
10. A lubricating oil composition as claimed in claim 1, wherein
component B is in the range of 0.1 to 10.0%, and preferably 0.5 to
6% w/w.

11. A lubricating oil composition for internal combustion gasoline and diesel engines as substantially as herein described and illustrated.

DATED

THIS

7TH

DAY

OF

FEBRUARY, 2000

of L . S . DAVAR & CO. , APPLICANTS' ATTORNEY