LUBE OIL ADDITIVES

LUBRICANTS• Lubricants were in use before the invention

of wheel.• Building block of 95% of today’s lubricants

is mineral oil.• Straight run MO not satisfactory for

operating under arduous conditions.• Modern Lubricant is highly refined HC

base stock+chemical additives.

WORLD LUBRICANT USES

4Automotive Transmissions

5Grease

9Process

27Industrial

55Engine

%APPLICATION

PERFORMANCE-WISE CLASSIFICATION OF ADDITIVES

Modifies crystal growth at low temperature

Pour Point Depressants

Improves viscosity – temp. relationships

Viscosity Index Improvers

Prevent formation of acid, minimize viscosity increase

Antioxidant

Reduce wear, minimize metal to metal contact

Antiwear/EP

Engine Cleanliness, keep sludge in suspension

Detergents Dispersants

PERFORMANCE-WISE CLASSIFICATION OF ADDITIVES

Control FoamingsDefoamant

Improves Adhesive Properties

Tackiness Agents

Neutralizes Catalytic Effect of Metals

Metal Deactivators

Prevent Corrosion of Ferrous and Non-ferrous surfaces

Corrosion/Rust/ Inhibitors

Reduce Friction between moving parts, improve engine efficiency

Friction Modifiers

DETERGENT/DISPERSANT ADDITIVE

• Major Use in Crankcase Oil

• Represent 70% of Total Additive Used in Engine Oil

FUNCTION OF DETERGENT/ DISPERSANT ADDITIVE

•Keep Particulate matter dispersed•Maintain Engine Cleanliness

DIRT IN ENGINE ARISES FROM•Below-by of products from incomplete combustion of fuel•Oil oxidation product•Engine wear

Dirt Leads to Deposit in Engine e.g. On Piston Known as Lacquer or Varnish on English Sump Known as Sludge

DETERGENTS

• Metal Containing Cleaning Agents

• Capable of dealing deposits/precursor generated under high temperature running conditions

PARTS OF DETERGENT

• A metal Al, Mg, Zn, Ba, Ca.

• An anionic component e.g.

carboxylate,

Alcoholate,

Phenate,

Sulphonate and

Salicylate.

• Oil Soluble Oleo-philic Component Straight or Branched Alkyl Group.

TYPES OF DETERGENTS

• Sulphonate

• Phenate• Salicylate• Phosphate• Neutral• Over Base

By-product of white oil

Synthetic From Alkyl Aromatic

OVER BASE ADDITIVES• Colloidal Disperson Of Metal Carbonate (10-3-1 Micron)• TECHNOLOGY IS COMPLEX TO MAKE STABLE

SUSPENSION• ESTIMATION

As TBN (500)Metal Ratio

• EFFECTIVE IN CONTROLLINGa) Corrosive Acid From Oil Oxidationb) Blow-by Of Combustion Product

PREPARATION OF OVER BASE ADDITIVE

• Phenate Over Base Are Prepared Similarly

• Phosphates are Phosphoric And Thio Phosphoric Acid Derivatives

SELECTION DEPENDS ON

• Severity Of Condition

• Anti Rust

• Anti Oxidant

• Load Carrying Properties

DISPERSANTS

• Non metallic ashless cleaning agents

• Effective in controlling cold-sludge in gasoline engine operating under low-temp. stop-start conditions

• Bipolar molecule having polar head non-polar tail

Head consist of P,O,N atoms

Tail HC moiety

ADDITIVES TYPES

• Succinimides

• Succinate Esters

• Mannich Type

• Phosphorus Based

MECHANISM OF ACTION

• Polar Group Absobs on Dirt Oliophillic Group Solubilize Complex in Oil

• React Dirt Precursors e.g. neutralizing acidic matter

• Solubilizing precursors within their micelle structure.

• Absorb on metal surface• Form coating on solid particulate and prevent their

agglomeration to form large particles.

USES OF DETERGENT / DISPERSANT ADDITIVES

• Essential for most of automotive oils

• Automotive oil for gasoline/diesel

• Rail road engine oil

• Marine Oil

• Two stroke engine

• Tractor Oil

• Automatic Transmission Fluid

OXIDATION INHIBITOR (AO)

• Lubricants like other natural products deteriorate during use when exposed to oxygen.

• Undergo complicated aging process.• Oxidation alter performance.• 1st oxidation product is hydroperoxides.• Hydroperoxide leads to variety of end products

like alcohol, aldehyde, ketone acid etc.• Eventually depositing as sludge, varnish, liquer.• Leading to equipment failure

R-H R` + H`

R` + O2 ROO`

Antioxidant perform as radical quenchers

R` + AO RH + AO`

2 AO` INERT PRODUCTS

MECHANISM OF ACTION

• Engine oil accounts 60-70% of automotive lubricants.

• 40-50% of all lubricants sold• Automotive engine oil driving force on AO

market• AV car temperature – 100o

• Hot spot temperature – 300o or more• Chain branching reactions are more prevalent in

high temperature oxidation.

For lube antioxidants is a mixture of peroxide destroyer (TDDP) and radical scavenger.

ADDITIVE TYPE

• Zn-Di-Thio phosphate

• Phenol

• Aromatic Nitrogen Compounds

• S- and P- Based Antioxidants

• Phenothiazine and Alkyl Derivatives

USES OF ANTIOXIDANTS

• Antioxidants are used in all type of Lubricant

• Cranckase Oil Mostly Use ZDDP

• Steam Turbine Hindered Phenol

• Jet Air Phenothiazine

Derivatives

CH2RO OH

NHC8H17C8H17

N

S

R

CNX2

S – M – S X2NC

S S

(XOC – CH2 – CH2)2 S, X – S – X, or X – Se - X

O

X= Alkyl, Aryl, alkylaryl

RO – P – OR

OR

RO – P – H

OR

OHINDERED PHENOL

DIPHENYL AMINE

PHENOTHIAZINE

DITHIOCARBAMATES

ORGANIC SULPHIDE OR SLENIDES

OTHER COMPUNDS GENERALLY USED IN ADDITION TO ZDDP

VISCOSITY INDEX IMPROVER AND POUR POINT DEPRESSANTS

• These are polymeric additives

• These additives are used to improve rheological properties of oils

• They do it by purely physical means

VISCOSITY INDEX IMPROVER

• VI is a number showing viscosity temperature characteristic of oil.

• Gear, Transmission, Crankcase oil should have

(a) Low viscosity at low temperature for startup (need low friction drag)

(b) Sufficient viscosity at higher running temperature.

TYPES OF VI IMPROVERS

• Oil Soluble Org. Polymer

• M wt range 50,000-150,000

(a) Hydrocarbons

(b) Esters

TYPES OF VI IMPROVERS

HYDROCARBON TYPE• PIB Poly-isobutylene• OCB Olefin Co-polymer

Poly Alkyl Styrene• HSDC Styrene Butadiene Co-polymer

Styrene – Isoprene Co-polymer

ESTER TYPEPMP [Poly Alkyl Acrylate

Styrene Maleic Acid Copolymer]

USES OF VI IMPROVERS

PMA 21%,

HSDC 17%,

OCP 67%

VI improver made possible the advent of multigrade oils e.g. SAE low 30 or SAE 15w40 for gasoline engine (67%) diesel engine (19%).

SELECTION DEPEND ON

• Requirement

• Other prop e.g. PPD, Dispersant

• Shear Stability

• Oxidation Thermal Stability

MECHANISM OF VISCOSITY MODIFICATION IN OIL

Exist as random coil• Swollen by lube oil• Volume determine viscosity increase• At low temp. polymer remain as compact mass• At high temp. coil open up• Compensate fall in viscosity

SolubilityTemperature

LOW

LOW

GOOD

HIGH

Oil associated with polymer

Polymer

USES OF VI IMPROVERS

• Automotive multi grade oils (engine, gear)

• Gear and transmissions oils

• Hydraulic fluids

• Industrial oils

• Dosage 2-6%

POUR POINT DEPRESSANTS

• At low temperature wax crystalize out and prevent flow of oil

• Dewaxing can reduce pour point - Reduces yield- Adversely effect VI

• PPD – syn chemical which prevent congelation• PPD offer effective and economical alternative to

dewaxing• PPD improve

- Low temperature fluidity- Low temp performance

• PPD mainly used in paraffinic oils

TYPES OF PP DEPRESSANTS

•Non Polymeric

•Polymeric

Recent Lit. indicate that majority of products are poly hydrocarbon HC-Ester co-polymer and ester co-polymer

MECHANISM OF ACTION (POUR POINT DEPPRESANT)

• PPD don’t’ prevent crystallization

• Change crystal habit

• Probably by adsorption

• Smaller crystals form

• Do not interlock

• Permit flow of oil

USES OF PP DEPRESSANTS

• Mono and multi grade Oil

• Gear & Transmission oil

• Hydraulic Fluid

• Compressor Oil

• Machinery Oil

LOAD CARRYING ADDITIVES (AW/EP)

• Aw and EP additives are incorporated to extend oil’s load carrying capabilities

• Important but less used

• Inter metallic contact occur at asperities under boundary lubrication resulting heavy wear

TYPES OF ADDITIVES

• Additive are active compounds of S,Cl and P S-CompoundsDibenzyl disulfide

• Butyl phenol disulfide• Sulfurised vegetable oils• Pb, Sb, Cd and Zn dithiocarbamates

Cl – CompoundsChlorinated wax

• Chlorinated fatty acids

TYPES OF ADDITIVES

P - CompoundsTri cresyl phosphates ZDDP

• Di-alkyl phosphates etc• P & S-Compounds

Zinc dialkyl dithio phosphatesCl & S - CompoundsChlorinated alkyl sulfide

• Sulfurised chloronaphthalene

MECHANISM OF ACTION

• Act by physical adsorption, chemisorption or chemical reaction with metal forming protective film

• Film not penetrated by asparities

• Prevent scoring and surface damage

USES OF AW/EP ADDITIVES

• Engine oil

• Gear and transmission oil

• Shock absorber oil

• Hydraulic oils

FRICTION MODIFIERS (FM)

• During start-up and shut-down sliding surfaces subjected to high load (mixed friction range)

• FM additives used, to prevent stick-slip oscillation, noise and reduce frictional force

• To save energy, reduce fuel consumption (additives known as FM)

• FM Similar to AW/ EP Additives

• FM are polar oil soluble materials

Only few gained commercial Acceptance

• Mo-dithiophosphate and carbonate complexes

• Dispersion of MoS2, graphite, PTFE

• Ash less carboxylic acid esters, their oligomers and amines, amides

TYPES OF FRICTION MODIFIERS

• Mechanism

• By physical adsorption

• Uses

• Engine oil

• Gear and transmission oil

• Industrial oil

• greases, etc.

MECHANISM AND USES

ANTIFOAMING AGENTS

• Requires where violent churning or agitation of oil occur

Effect of Foams on the Performance of Engine

• Rise oil level,results in loss of oil

• Oil feed pressure drops,

• Insufficient oil supply

TYPES OF ADDITIVES

• POLYMERICi) Poly organo siloxane

CH3 CH3 CH3

Si O Si O Si O

CH3 CH3 CH3

ii) Poly acrylateIii) poly ethylene oxides

DOSAGE 4-15 ppm

n

MECHANISM OF ACTION

• Oil insoluble

• Lower interfacial tension between air and oil

• Permitting easy aggregation of air

• Reduce foam stability

USES ANTIFOAMING AGENTS

• Engine oils (automotive, rail, marine)

• Gear oils

• Automotive transmission fluids

• Industrial oils

• Metal working oils

RUST AND CORROSION INHIBITORS

• Rust and corrosion of metal parts undesirable

• Leads to wear and break down

RUST INHIBIOTRS

• RESULT OF CHEMICAL ATTACK OF WATER IN PRESENCE OF OXYGEN

• A large variety of compounds patented mostly three types:a. Neutral b. Acidic c. Overbased

• Most Popular are• High mil. Wt. Carboxylic acid (Succinic acid) • Sulphonic acid• Phosphoric acid and their salts• Compounds formed by neutralization of these

acids with organic base (e.g. Amines)

TYPES OF RUST INHIBITORS

MECHANISM OF ACTION

• Physical Means

• Work by forming strongly absorbed hydrophobic film

CORROSION INHIBITORS• Corrosion occur due to attack of acid• Arising from

A) oil oxidation (org>)B) blow-by of combustion products

(SO2 inorg)• Later sever in diesel engine

ADDITIVE TYPES

• Metal dialkyl dithio phosphates,

• Phospho sulphurized olefins, terpenes

• Org Phosphites,

• Dithio carbamate• Most popular are basic detergent /

dispersant additive

MECHANISM OF ACTION

• Forming absorbed protective films

• By neutralizing acid materials

• Also acts as Antioixdants, load-carrying additives

MISCELLANEOUS LUBE ADDITIVES

• Anti-microbial agents used in cutting oil emulsions

• Emulsifiers to manuf. Water based cutting oils

• Odour masking agents• Dyes for identifications

MISCELLANEOUS ADDITIVES

• Tackiness agents impart stickiness/ adherence property (PIB, ethylene-propylene co-polymer)

• Seal swalling agent to help swalling of rubber elastomers to required volume (phthalic acid ester, most popular di-octyl phthalate [DOP]

SOME GENERAL TYPE OF ADDITIVES USED IN A WIDE VARIETY OF LUBRICANTS

Seal Swell

Pour Point

Viscosity Improvers

Antifoam Agents

Extreme Pressure Agents

Friction Modifiers

Corrosion Inhibitors

Rust Inhibitors

Antiwear Agents

Antioxidant

Ashless Dispersant

Metallic Detergent

Metal Working Fluids

Turbine Oils

Gear Oils

Hydraulic Oils

Axle Oils

Automatic Trans. Fluid

Engine Oil

LUBRICANT TYPEADDITIVE