FORM-2
THE PATENTS ACT. 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003 COMPLETE SPECIFICATION
(See Section 10; Rule 13)
1. TITLE OF THE INVENTION:
"ECO-FRIENDLY CORROSION INHIBITOR FOR TREATING COOLING WATERS USED IN ENGINES".
2. APPLICANTS:
(a) NAME: HINDUSTAN PETROLEUM CORPORATION LIMITED.
(b) NATIONALITY: INDIAN COMPANY.
(c) ADDRESS: RESEARCH & DEVELOPMENT CENTRE,
PLOT D-500, TTC AREA OF MIDC, NAVI MUMBAI-400 705, MAHARASHTRA, INDIA.
The following specification describes the nature of the invention and the manner in which it is to be performed:-

AN ECO-FRIENDLY CORROSION INHIBITOR FOR TREATING COOLING WATERS USED IN ENGINES
3. PREAMBLE TO THE DESCRIPTION
Field of Invention
The present invention relates to the development of an eco-friendly corrosion inhibitor for treating cooling waters used in engines.
Introduction
The purpose of the automotive engine cooling system and the coolant is to control metal temperatures within the safe limits by removing excess heat produced by the engine while running. It also prevents the freeze-up in winter and boil-over in summer (especially in cars with air conditioners). When the metal temperature is not controlled by an adequate cooling, there are chances of the lubrication failure and may result in the serious damage to the engine.
The performance requirements of coolant became more severe during the 1980's. What was once a commodity product, primarily aimed at providing freezing protection for the cooling system of internal combustion engines, became a complex product containing a delicate balance of additives designed to meet many stringent requirements. The increased awareness of the importance of coolant was prompted by the introduction of more efficient engines operating at higher temperature, the use of light metals and plastics in the cooling system and the growing concern relative to the toxicological and ecological aspects of the coolant itself.
The reduction of the overall mass of the vehicles to improve the fuel economy entailed extensive use of light materials such as aluminum and plastics for the

construction of engine and cooling system parts. The volume of coolant used was also drastically reduced to further reduce the weight, subjecting the coolants to high rates of flow, high temperatures and significant metal-to-coolant heat fluxes.
Today's smaller, efficient and powerful engines dissipate more heat, requiring that the coolant to keep the heat exchange surfaces in the clean condition. In addition, corrosion, which in itself is of concern, can also result in the deposition of bulky corrosion products that will impede the heat transfer.
Initial-fill user requirements and specifications are changing rapidly and contain the demands for a cooling fluid that is:
• an effective heat exchange fluid
• capable of providing the freezing and the boiling protection
• compatible with the plastic and the elastomers,
• chemically stable at the low and the high temperatures
• compatible with hard water
• low foaming and
• ecologically and toxicologically acceptable
These requirements are met by the development of multi component coolants that provide a low freezing point, high thermal conductivity and specific heat, good fluidity, elevated boiling point, low toxicity, chemical stability and proper balance of supplemental additives. A corrosion inhibitor package is usually present at a concentration of two to five percent. Other additives, which may be present, include stabilizing agents to improve the hard water stability of inhibitors that form insoluble calcium salts, sequestering agents to inhibit deposit formation, antifoamants to inhibit excessive foaming and a dye to characterize the product.

There are many requirements for an acceptable engine coolant the most essential of these are:
• The ability of lower the freezing point of water to the lowest winter operating temperatures likely to be encountered.
• The ability to protect the cooling system metals from corrosion & deposits.
• A minimum of undesirable effects on engine cooling and heat transfer.
• No deleterious effect on rubber.
• The chemical stability.
• Minimum effect on automobile finishes.
• An acceptable viscosity at low temperatures.
• Low coefficient of expansion.
• Usability for at least one year of service.
• Little or no odor.
• Easily checked freezing point.
• Low cost.
In addition to above, low toxicity, suitable boiling point characteristics, low foaming and operating losses, and non-falmmability are desirable parameters.
In order to achieve the above characteristics, normally Water - Ethylene glycol formulations are employed today as they provide year - round, cost effective freezing, boiling and corrosion protection. They are chemically stable and are compatible with elastomers and plastics used in cooling systems. The physical properties of some of the components is provides in Table below:

TYPICAL PHYSICAL PROPERTIES OF COOLING SYSTEM COMPOUNDS
PROPERTY WATER METHANOL ETH GLYCOL PROP GLYCOL
Specific Gravity, 20/20°C 1.0000 0.7924 1.1155 1.0381
Speicfic Heat, cal/g.°C 0.9980 0.6000 0.5740 0.6000
Freezing Point, °C Pure 50% solution 0 -97.7 -44.5 -13.3 -36.6 -33
Boiling Point, °C 100 65 197 187
Vapout pressure, 20°C, mmHg 17.5 96.1 0.12 0.18
Flash Point, °C - 15.6 115.6 107.2
Viscosity, cP 20°C 40°C 100°C 1 0.65 0.28 0.6 0.48 20.99.11.8 60.5 19.3 2.6
It can be observed that, the heat exchange capacity of ethylene glycol/water solutions is reduced with increasing the ethylene glycol content. The water remains a better heat exchange fluid compared to the mixture. A compromise has to be made between the heat exchange capacity and the freeze protection. Also, a lower viscosity will aid heat exchange in case of water. Again, a compromise is made between the freeze protection and the fluidity.
In past the water alone was used as the coolant and understanding the Indian environmental conditions similar to tropical regions has again led us to believe that instead of glycol mixture, inhibited water will still be a better option for the

cooling systems where the operating temperatures of vehicles may not be high or are thermostated below 100°C, and the pressurized systems is predominant.
A detailed survey of the fleets operating with Indian Railways, State Transport Undertakings and discussions held with a few Original Equipment Manufacturers revealed that, they also would like to do away with the EG based coolants because of the inconsistent water qualities, the fluctuating prices of ethylene glycols and in response to the current problems of the water galleries of engines getting choked, scales/deposit formations in the water galleries with the current coolants (this was happening due to the coolant degradation over time as the ethylene glycol breaks down into the primarily glycolic and the formic acids lowering the pH) provided a solution can be found.
Earlier water based corrosion inhibitors used chromate based concentrate technology which causes serious environmental hazard when discharged through the drains. In order to eliminate the harmful affects, the Borate Nitrite based concentrated inhibitors were introduced and are currently in use. However, this does not eliminate the problem since, the ground water pollution from Boron and nitrite has become a serious concern. This led to development of benzoate nitrite based concentrates eliminating the hazards of boron pollution but the nitrite still remained. In their pursuit towards for the cleaner environment, various users were on the lookout for a more environment friendly and biodegradable concentrated product which should also provide an adequate protection to their engine.
In order to tackle the problems a water based coolant concentrate, compatible with hard water, chemically stable, ecologically responsive and non toxic technology was developed and extensively tested in the laboratory.

Main Features of the product,
• Carboxylate based non toxic product.
• Free from Amine, Boron, Silicate, Phosphate and Chromate.
• Fully Bio-degradable.
• Excellent hard water compatibility, works with both tap water and DM water.
• All weather product applications in India.
• Provides excellent protection to all metal rubber parts.
The conventional inhibitors work by forming a protective blanket that actually insulates the metals from the water. These inhibitors can be characterized chemically as inorganic oxides (borates, benzoates, nitrites, nitrates etc.). Because these inhibitor systems are depleted by forming a protective layer, the conventional coolants needed to be changed at the regular intervals or required a continuous monitoring of the product whereas the "organic additive technology" (OAT) uses the inhibitors derived from carboxylic acids. In reality, the protection is provided by neutralized carboxylic acids called carboxylates. Carboxylate inhibitors provide a corrosion protection by chemically interacting with the metal surfaces where needed and not by universally laying down layers, which is the case with the conventional coolants. The implications of these functional differences are enormous like: extended life cycles, unsurpassed high temperature aluminum protection, as well as heat transfer advantages on both hot engine surfaces and heat-rejecting radiator tubes where heat transfer is critical to optimal performance.
Summary of the Invention
The use of carboxylates, triazoles and thiadazoles is well known in glycol based concentrate systems due to a very good solubility of the organic compounds in

ethanol, 2,2'-{[(4-methyl-lH-benzotriazol-l-yl)-methyl] imino} bis called D for further reference.
4. Forty to fifty portions of C, 10 to 20 portions of A & B in a 50:50 ratio were mixed with 3 portions of D. The balance was water making total of 100 portions.
5. The concentrate obtained in 4 was diluted to 3% in water and then tested for standard parameters. The results are as under.

Sr. No. Test Description Results S.No. Radiator Coolant
1 Density Neat Concentrate 20°C g/cm3 1.212
2 Boiling Point, Neat Concentrate °C 117
3 Foaming property ml 3 vol. % aqueous solution Nil
4 Water content % , Neat Concentrate 71.6
5 pH Value (Ordinary Temp.) 3 vol. % aqueous solution 8.18
6 Reserved Alkalinity, ml, Neat Concentrate 26.9
7 Corrosion Property of Cast Aluminium at Heat Transfer Surface wt. Change mg/cm2, 3 vol. % test solution 135 ±2°C 168 ±2hrs. Run I -0.033 Run II -0.047

glycols. In water these compounds have negligible to a very limited solubility. A technique was developed by proportionating the compounds and reacting them with potassium, in such a way that, the issue of solubility is resolved to the extent that, no glycol is required.
4. DESCRIPTION OF THE INVENTION
Manufacture of Coolant
1. The potassium carboxylates of 2 ethyl hexanoic acid, ocatanoic acid, C8&C9 dicarboxylic acids were prepared by reacting stoichiometric amounts of potassium and the respective acids in the separate small vessels of capacity 5 liters (batch size 2kgs each) called A & B for further reference
2. Polycarboxylic acid of general formula C21N6O6H36 (mol wt 470 avg.) was reacted in major 20 liters capacity (batch size 10 kg.) vessel by refluxing a saturated solution of potassium hydroxide and stoichiometric ratio of polycarboxylic acid. The reaction mixture was clear after 2 hours of reaction. The pH of the product was adjusted to 7.0-7.5 by adding additional quantities of potassium hydroxide/polycarboxylic acid. This admixture (called C for further reference) solublises organic components which are usually not soluble in water.
3. Isomeric mixture of ethanol, 2,2'-[[(5-methyl-lHbenzotriazole-l-yl)-methyl]imino]bis- and ethanol, 2,2'-[[(4-methyl-lH-benzotriazol-l-yl)-methyl]imino]bis salt of potassium was prepared by reacting potassium metal with Isomeric mixture of ethanol, 2,2'-[[(5-methyl-lHbenzotriazole-l-yl)-methyl]imino]bis- and ethanol, 2,2'-[[(4-methyl-lH-benzotriazol-l-yl)-methyl]imino]bis in isopropyl alcohol and after completion of reaction, isopropyl alcohol was recovered from the solution. The potassium salt of ethanol, 2,2'-{[(5-methyl-lHbenzotriazole-l-yl)-methyl] imino} bis- and

Sr. No. Test Description Results □
Set I Set II Set III Mean Value
8 Metal CorrosionProperty 3 Vol. % testsolution, 336 ± 2 hrs. at 88 ± 2°C For metal test pieces weight changes in mg/cm2
8.1 (a) Aluminum Casting -0.0559 0.0874 0.0765 0.0733
(b) Cast Iron -0.0188 0.0199 0.0183 0.0190
(c) Steel 0.0003 0.0009 0.0007 0.0004
(d)Brass -0.0666 0.0457 0.0523 0.0549
(e) Solder -0.0990 0.0970 0.0840 0.0933
(f) Copper -0.0032 0.0064 0.0740 0.0279
8.2 Appearance There is no visually noticeable corrosion on the test pieces excluding the part in contact with spacer. There is no change in colour of strips.
8.3 Foaming property during the test No foam flooded out from the cooler.
8.4 Properties of solution after the test
(a) pH Value 8.15 8.14 8.18 8.16
(b) Change of pH -0.1 -0.1 -0.2 -0.13
(c) Rate of Change Reserve Alkalinity % -3.7 -5.9 -5.9 -5.17
(d) Liquid Phase There is no significant change of colour. There is no significant change in liquor such as separation or generation of gel.
(e) Amount of precipitate, vol. % Nil Nil Nil Nil

Sr.No. Test Description Specified Value as per JIS K-2234-94, Class 2 Results S.No. Radiator Coolant
Set I Set II Set III Mean Value
9 Metal Corrosion Property 3 Vol. % test solution, 1000 ± 2 hrs. at88 ± 2°C For metal test pieces weight changes in mg/cm2
9.1D Aluminum Casting ±0.60 0.1233 -0.1523 -0.1217 0.1324
Cast Iron ±0.30 0.0104 -0.0093 -0.0116 0.0104
Steel ±0.30 0.0237 -0.0247 -0.0373 0.0286
Brass ±0.60 0.0423 -0.0417 -0.0421 0.0420
Solder ±0.30 0.0987 -0.0932 -0.1216 0.1045
Copper ±0.30 0.0037 -0.0075 -0.0037 0.0050
9.2 Appearance There shall be no visually noticeable corrosion on the test pieces excluding the part in contact with the spacer, but change in colour is permissible. There is no visually noticeable corrosion on the test pieces excluding the part in contact with spacer. There is no change in colour of strips.
9.3 Properties of solution after the test
(a) pH Value 6.5 to 11.0 8.04 8.04
(b) Change of pH ±1.0 -0.31 -0.31

(c) Rate of Change Reserve Alkalinity % To be reported -4.7 -4.7
(d) Liquid Phase No significant change in colour. No significant change in liquor such as separation or generation of gel. There is no significant change of colour. There is no significant change in liquor such as separation or generation of gel.
9.4 Condition of Parts
Sealing Part of Pump No failure duringoperation. No liquid leakage nor unusual sound. There was no failure during operation. There was no liquid leakage. There was no abnormal sound.
Internal surface of pump casing & vanes of pump No serious corrosion There was no serious corrosion.
CONCLUSIONS:
The use of carboxylates, triazoles and thiadazoles is well known in glycol based concentrate systems due to very good solubility of the organic compounds in glycols. In the water these compounds have a negligible to a very limited solubility. A technique was developed by proportionating the compounds and reacting them with potassium in such a way that, the issue of solubility is resolved to the extent that, no glycol is required.

5. WE CLAIM:
1. An eco-friendly corrosion inhibitor for treating cooling waters used in engines to control metal temperatures within the safe limits by removing excess heat produced by the engine while running and also preventing the freeze-up in winter and boil-over in summer.
2. An eco-friendly corrosion inhibitor for treating cooling waters used in engines as claimed in the claim 1 above, having proportion of carboxylic acid:triazole:thiadiazole salts of potassium.
3. An eco-friendly corrosion inhibitor for treating cooling waters used in engines as claimed in the claims 1 & 2 above, having preparation of corrosion inhibitor concentrate in water.
4. An eco-friendly corrosion inhibitor for treating cooling waters used in engines as claimed in the claims 1, 2 & 3 above, having a mixture of components: carboxylic acids: 2 ethyl hexanoic acid, ocatanoic acid, C8&C9 dicarboxylic acids, Isomeric mixture of ethanol, 2,2'-{[(5-methyl-lHbenzotriazole-l-yl)-methyl] imino} bis - and ethanol, 2,2'-{[(4-methyl-lH-benzotriazol-l-yl)-methyl] imino} bis and ploycarboxylic acid of general formula C21N6O6H36 (mol wt 470 avg.).
5. An eco-friendly corrosion inhibitor for treating cooling waters used in engines as claimed in the claims 1, 2, 3 & 4 above, having the potassium carboxylates of 2 ethyl hexanoic acid, ocatanoic acid, C8&C9 dicarboxylic acids being prepared by reacting stoichiometric amounts of potassium and

respective acids in separate small vessels of capacity 5 liters (batch size 2kgs each) being called A&B for further reference.

6. An eco-friendly corrosion inhibitor for treating cooling waters used in engines as claimed in the claims 1, 2, 3, 4 & 5 above, having Polycarboxylic acid of general formula C21N6O6H36 (mol wt 470 avg) being reacted in major 20 liters capacity (batch size 10 kg.) vessel by refluxing a saturated solution of potassium hydroxide and stoichiometric ratio of polycarboxylic acid and further the reaction mixture getting clear after 2 hours of reaction and further the pH of the product being adjusted to 7.0 - 7.5 by adding an additional quantities of potassium hydroxide/polycarboxylic acid and further this admixture (called C for further reference) solublises organic components which usually not being soluble in water.

7. An eco-friendly corrosion inhibitor for treating cooling waters used in engines as claimed in the claims 1, 2, 3, 4, 5 & 6 above, having isomeric mixture of ethanol, 2,2'-{[(5-methyl-lHbenzotriazole-l-yl)-methyl] imino} bis- and ethanol, 2,2'-{[(4-methyl-lH-benzotriazol-l-yl)-methyl] imino} bis salt of potassium being prepared by reacting potassium metal with Isomeric mixture of ethanol, 2,2'- {[(5 -methyl-1 Hbenzotriazole-1 -yl)-methyl] imino} bis - and ethanol, 2,2'-{(4-methyl-lH-benzotriazol-l-yl)-methyl] imino} bis in isopropyl alcohol and after completion of reaction, isopropyl alcohol being recovered from the solution, further, the potassium salt of ethanol, 2,2'-{[(5-methyl-lHbenzotriazole-l-yl)-methyl] imino} bis - and ethanol, 2,2'-{[(4-methyl-lH-benzotriazol-l-yl)-methyl] imino} bis being called D for further reference.

8. An eco-friendly corrosion inhibitor for treating cooling waters used in engines as claimed in the claims 1, 2, 3, 4, 5, 6 & 7 above, having forty to fifty portions of C, 10 to 20 portions of A&B in 50:50 ratio being mixed with 3 portions of D and the balance being water making total of 100 portions.
9. An eco-friendly corrosion inhibitor for treating cooling waters used in engines as claimed in the claims 1, 2, 3, 4, 5, 6, 7 & 8 above, having, the concentrate obtained in 4 being diluted to 3% in water and tested for standard parameters.


7. ABSTRACT
The use of carboxylates, triazoles and thiadazoles is well known in glycol based concentrate systems due to very good solubility of the organic compounds in glycols. In water these compounds have negligible to very limited solubility. A technique was developed by proportionating the compounds and reacting them with potassium in such a way that the issue of solubility is resolved to the extent that no glycol is required. The concentrate thus prepared is used as corrosion inhibitor for preparing cooling water for stationary and mobile engines. The product thus formed fully complies with the Central pollution Control board requirements of disposal.